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Sample records for active transport process

  1. Energetics of active transport processes.

    PubMed

    Essig, A; Caplan, S R

    1968-12-01

    Discussions of active transport usually assume stoichiometry between the rate of transport J(+) and the metabolic rate J(r). However, the observation of a linear relationship between J(+) and J(r) does not imply a stoichiometric relationship, i.e., complete coupling. Since coupling may possibly be incomplete, we examine systems of an arbitrary degree of coupling q, regarding stoichiometry as a limiting case. We consider a sodium pump, with J(+) and J(r) linear functions of the electrochemical potential difference, -X(+), and the chemical affinity of the metabolic driving reaction, A. The affinity is well defined even for various complex reaction pathways. Incorporation of a series barrier and a parallel leak does not affect the linearity of the composite observable system. The affinity of some region of the metabolic chain may be maintained constant, either by large pools of reactants or by regulation. If so, this affinity can be evaluated by two independent methods. Sodium transport is conveniently characterized by the open-circuit potential (Deltapsi)(I=0) and the natural limits, level flow (J(+))(X+=0), and static head X(0) (+) = (X(+))(J+=0). With high degrees of coupling -X(0) (+)/F approaches the electromotive force E(Na) (Ussing); -X(0) (+)/F cannot be identified with ((RT/F) ln f)(X+=0), where f is the flux ratio. The efficiency eta = -J(+)X(+)/J(r)A is of significance only when appreciable energy is being converted from one form to another. When either J(+) or -X(+) is small eta is low; the significant parameters are then the efficacies epsilon(J+) = J(+)/J(r)A and epsilon(X+) = -X(+)/J(r)A, respectively maximal at level flow and static head. Leak increases both J(+) and epsilon(J+) for isotonic saline reabsorption, but diminishes -X(0) (+) and epsilon(Xfemale symbol). Electrical resistance reflects both passive parameters and metabolism. Various fundamental relations are preserved despite coupling of passive ion and water flows.

  2. Saharan Dust, Transport Processes, and Possible Impacts on Hurricane Activities

    NASA Technical Reports Server (NTRS)

    Lau, William K. M.; Kim, K. M.

    2010-01-01

    In this paper, we present observational evidence of significant relationships between Saharan dust outbreak, and African Easterly wave activities and hurricane activities. We found two dominant paths of transport of Saharan dust: a northern path, centered at 25degN associated with eastward propagating 6-19 days waves over northern Africa, and a southern path centered at 15degN, associated with the AEW, and the Atlantic ITCZ. Seasons with stronger dust outbreak from the southern path are associated with a drier atmosphere over the Maximum Development Region (MDR) and reduction in tropical cyclone and hurricane activities in the MDR. Seasons with stronger outbreak from the northern path are associated with a cooler N. Atlantic, and suppressed hurricane in the western Atlantic basin.

  3. Community Vision and Interagency Alignment: A Community Planning Process to Promote Active Transportation.

    PubMed

    DeGregory, Sarah Timmins; Chaudhury, Nupur; Kennedy, Patrick; Noyes, Philip; Maybank, Aletha

    2016-04-01

    In 2010, the Brooklyn Active Transportation Community Planning Initiative launched in 2 New York City neighborhoods. Over a 2-year planning period, residents participated in surveys, school and community forums, neighborhood street assessments, and activation events-activities that highlighted the need for safer streets locally. Consensus among residents and key multisectoral stakeholders, including city agencies and community-based organizations, was garnered in support of a planned expansion of bicycling infrastructure. The process of building on community assets and applying a collective impact approach yielded changes in the built environment, attracted new partners and resources, and helped to restore a sense of power among residents.

  4. Silicon uptake and transport is an active process in Cucumis sativus.

    PubMed

    Liang, Yongchao; Si, Jin; Römheld, Volker

    2005-09-01

    Cucumis sativus is a species known to accumulate high levels of silicon (Si) in the tops, though the mechanism for its high Si uptake is little understood. In a series of hydroponic experiments, we examined uptake and xylem loading of Si in C. sativus along with Vicia faba at three levels of Si (0.085, 0.17 and 1.70 mm). Measured Si uptake in C. sativus was more than twice as high as calculated from the rate of transpiration assuming no discrimination between silicic acid and water in uptake. Measured Si uptake in V. faba, however, was significantly lower than the calculated uptake. Concentration of Si in xylem exudates was several-fold higher in C. sativus, but was significantly lower in V. faba compared with the Si concentration in external solutions, regardless of Si levels. Silicon uptake was strongly inhibited by low temperature and 2,4-dinitrophenol, a metabolic inhibitor, in C. sativus but not in V. faba. It can be concluded that Si uptake and transport in C. sativus is active and independent of external Si concentrations, in contrast to the process in V. faba.

  5. Process-based model linking pocket gopher (Thomomys bottae) activity to sediment transport and soil thickness

    NASA Astrophysics Data System (ADS)

    Yoo, Kyungsoo; Amundson, Ronald; Heimsath, Arjun M.; Dietrich, William E.

    2005-11-01

    Burrowing organisms assist in shaping earth surfaces and are simultaneously affected by the environment they inhabit; however, a conceptual framework is not yet available to describe this feedback. We introduce a model that connects the population density of soil-burrowing animals to sediment transport via energy. The model, combined with available data from California hillslopes where soil erosion is driven by pocket gophers (Thomomys bottae), suggests that a gopher annually expends ˜9 kJ of energy, or ˜1% of reported burrowing energy expenditure, in generating sediment transport. The model is used to evaluate the case that gophers prefer to populate thicker soils. The results suggest that this behavior may drastically dampen the spatial and temporal variations of soil thickness and gopher populations, implying that burrowing organisms may create landscapes distinct from those affected by abiotic processes.

  6. Transport to Rhebpress activity.

    PubMed

    Garrido, Amanda; Brandt, Marta; Djouder, Nabil

    2016-01-01

    The small GTPases from the rat sarcoma (Ras) superfamily are a heterogeneous group of proteins of about 21 kDa that act as molecular switches, modulating cell signaling pathways and controlling diverse cellular processes. They are active when bound to guanosine triphosphate (GTP) and inactive when bound to guanosine diphosphate (GDP). Ras homolog enriched in brain (Rheb) is a member of the Ras GTPase superfamily and a key activator of the mammalian/mechanistic target of rapamycin complex 1 (mTORC1). We recently determined that microspherule protein 1 (MCRS1) maintains Rheb at lysosomal surfaces in an amino acid-dependent manner. MCRS1 depletion promotes the formation of the GDP-bound form of Rheb, which is then delocalized from the lysosomal platform and transported to endocytic recycling vesicles, leading to mTORC1 inactivation. During this delocalization process, Rheb-GDP remains farnesylated and associated with cellular endomembranes. These findings provide new insights into the regulation of small GTPases, whose activity depends on both their GTP/GDP switch state and their capacity to move between different cellular membrane-bound compartments. Dynamic spatial transport between compartments makes it possible to alter the proximity of small GTPases to their activatory sites depending on the prevailing physiological and cellular conditions.

  7. Activated transport in AMTEC electrodes

    NASA Technical Reports Server (NTRS)

    Williams, R. M.; Jeffries-Nakamura, B.; Ryan, M. A.; Underwood, M. L.; O'Connor, D.; Kikkert, S.

    1992-01-01

    Transport of alkali, metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. The temperature dependence of the diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and preexponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process.

  8. Activated transport in AMTEC electrodes

    SciTech Connect

    Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O`Connor, D.; Kikkert, S.

    1992-07-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

  9. Activated transport in AMTEC electrodes

    SciTech Connect

    Williams, R.M.; Jeffries-Nakamura, B.; Ryan, M.A.; Underwood, M.L.; O'Connor, D.; Kikkert, S.

    1992-01-01

    Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and pre-exponential, but at least two activated processes may be operative, and the activation parameters should be expected to depend on the alkali metal activity gradient that the electrode experiences. In the case of Pt/W/Mn electrodes operated for 2500 hours, limiting currents varied with electrode thickness, and the activation parameters could be assigned primarily to the surface/grain boundary diffusion process. 17 refs.

  10. Anatomy of mass transport deposits in the Dead Sea: sedimentary processes in an active tectonic hypersaline basin

    NASA Astrophysics Data System (ADS)

    Waldmann, Nicolas; Hadzhiivanova, Elitsa; Neugebauer, Ina; Brauer, Achim; Schwab, Markus; Frank, Ute; Dulski, Peter

    2014-05-01

    Continental archives such as interplate endorheic lacustrine sedimentary basins provide an excellent source of data for studying regional climate, seismicity and environmental changes through time. Such is the case for the sediments that were deposited in the Dead Sea basin, a tectonically active pull-apart structure along the Dead Sea fault (DSF). This elongated basin is characterized by steep slopes and a deep and flat basin-floor, which are constantly shaped by seismicity and climate. In this study, we present initial results on the sedimentology and internal structure of mass transport deposits in the Pleistocene Dead Sea. The database used for this study consists of a long core retrieved at ~300 m water depth in the deepest part of the Dead Sea as part of an international scientific effort under the auspice of the ICDP. Micro-facies analysis coupled by elemental scanning (µXRF), granulometry and petrophysical measurements (magnetic susceptibility) have been carried out on selected intervals in order to decipher and identify the source-to-sink processes and controlling mechanisms behind the formation of mass transport deposits. The findings of this study allowed defining and characterizing the mass transport deposits into separate sedimentary facies according to the lake level and limnological conditions. Investigating sediments from the deep Dead Sea basin allowed better understanding and deciphering the depositional processes in relation with the tectonic forces shaping this basin.

  11. The Role of EPS in Microhydrology and Transport Processes Affecting Microbial Activity in Unsaturated Porous Media

    NASA Astrophysics Data System (ADS)

    Or, D.; Phutane, S.

    2005-12-01

    Extra-cellular Polymeric Substances (EPS) refers to biopolymers excreted and surrounding soil bacterial cells (and other biota) forming the scaffolding for colonies and serving a wide array of transport, nutrient entrapment, and mechanical functions. In essence, EPS is a porous matrix through which aqueous, gaseous and nutrient fluxes flow to supply the embedded bacterial cells. The large water holding capacity and retarded water loss rates of EPS dampens rapid fluctuations in hydration status of host porous medium which sustain higher diffusion fluxes than in surrounding porous medium, and shelters microbial cells from effect of rapid desiccation or rewetting. The morphology of EPS changes from an open well-hydrated bioweb to dense and highly cross-linked structure under dry conditions. Such morphological changes are accompanied by enhanced mechanical strength and retardation of water loss that provide additional time for physiological adaptation to desiccation. Additional capacitance results from the disparity in dynamic hydrological properties between EPS and soil that promotes water entrapment in EPS during rapid drainage. EPS may also trap dissolved nutrients that may be unevenly distributed and irregularly supplied in unsaturated environments, thereby increasing nutrient availability in the microhabitat and offsetting decreased supply by diffusion during drying. The remarkable transport and mechanical properties of EPS makes it an important stabilizing agent for soil aggregation and even minute amounts of EPS may significantly alter macroscopic hydrological properties of host porous medium.

  12. Suppression of flow pulsation activity by relaxation process of additive effect on viscous media transport

    NASA Astrophysics Data System (ADS)

    Kharlamov, S.; Dedeyev, P.; Meucci, L.; Shenderova, I.; Manastirniy, A.; Usenko, M.

    2015-11-01

    The article presents the analysis of the processes occurring together with the turbulent transfer of impulse in mixture of hydrocarbon fluid and polymer solutions (anti-turbulent additives). The study evaluates complex shear flows by popular theoretical and practical methods. Understanding of hydrodynamic and dissipative effects of laminar-turbulent transition tightening and turbulence suppression is provided. The peculiarities of "thin" flow structure in pipeline zones with complex shape walls are evaluated. Recommendations to forecast the local flow parameters, calculation of hydraulic resistance are given.

  13. Crew Transportation Technical Management Processes

    NASA Technical Reports Server (NTRS)

    Mckinnie, John M. (Compiler); Lueders, Kathryn L. (Compiler)

    2013-01-01

    Under the guidance of processes provided by Crew Transportation Plan (CCT-PLN-1100), this document, with its sister documents, International Space Station (ISS) Crew Transportation and Services Requirements Document (CCT-REQ-1130), Crew Transportation Technical Standards and Design Evaluation Criteria (CCT-STD-1140), Crew Transportation Operations Standards (CCT STD-1150), and ISS to Commercial Orbital Transportation Services Interface Requirements Document (SSP 50808), provides the basis for a National Aeronautics and Space Administration (NASA) certification for services to the ISS for the Commercial Provider. When NASA Crew Transportation System (CTS) certification is achieved for ISS transportation, the Commercial Provider will be eligible to provide services to and from the ISS during the services phase.

  14. Transport Phenomena and Materials Processing

    NASA Astrophysics Data System (ADS)

    Kou, Sindo

    1996-10-01

    An extremely useful guide to the theory and applications of transport phenomena in materials processing This book defines the unique role that transport phenomena play in materials processing and offers a graphic, comprehensive treatment unlike any other book on the subject. The two parts of the text are, in fact, two useful books. Part I is a very readable introduction to fluid flow, heat transfer, and mass transfer for materials engineers and anyone not yet thoroughly familiar with the subject. It includes governing equations and boundary conditions particularly useful for studying materials processing. For mechanical and chemical engineers, and anyone already familiar with transport phenomena, Part II covers the many specific applications to materials processing, including a brief description of various materials processing technologies. Readable and unencumbered by mathematical manipulations (most of which are allocated to the appendixes), this book is also a useful text for upper-level undergraduate and graduate-level courses in materials, mechanical, and chemical engineering. It includes hundreds of photographs of materials processing in action, single and composite figures of computer simulation, handy charts for problem solving, and more. Transport Phenomena and Materials Processing: * Describes eight key materials processing technologies, including crystal growth, casting, welding, powder and fiber processing, bulk and surface heat treating, and semiconductor device fabrication * Covers the latest advances in the field, including recent results of computer simulation and flow visualization * Presents special boundary conditions for transport phenomena in materials processing * Includes charts that summarize commonly encountered boundary conditions and step-by-step procedures for problem solving * Offers a unique derivation of governing equations that leads to both overall and differential balance equations * Provides a list of publicly available computer

  15. Political activity for physical activity: health advocacy for active transport

    PubMed Central

    2011-01-01

    Effective health advocacy is a priority for efforts to increase population participation in physical activity. Local councils are an important audience for this advocacy. The aim of the current study was to describe features of advocacy for active transport via submissions to city council annual plans in New Zealand, and the impact of an information sheet to encourage the health sector to be involved in this process. Written submissions to city council's annual consultation process were requested for 16 city councils over the period of three years (2007/08, 2008/09, and 2009/10). Submissions were reviewed and categories of responses were created. An advocacy information sheet encouraging health sector participation and summarising some of the evidence-base related to physical activity, active transport and health was released just prior to the 2009/10 submission time. Over the period of the study, city councils received 47,392 submissions, 17% of which were related to active transport. Most submissions came from city residents, with a small proportion (2%) from the health sector. The largest category of submissions was in support of pedestrian and cycling infrastructure, design and maintenance of facilities and additional features to support use of these transport modes. Health arguments featured prominently in justifications for active transport initiatives, including concerns about injury risk, obesity, physical inactivity, personal safety and facilities for people with disabilities. There was evidence that the information sheet was utilised by some health sector submitters (12.5%), providing tentative support for initiatives of this nature. In conclusion, the study provides novel information about the current nature of health advocacy for active transport and informs future advocacy efforts about areas for emphasis, such as health benefits of active transport, and potential alliances with other sectors such as environmental sustainability, transport and urban

  16. Laboratory Exercise on Active Transport.

    ERIC Educational Resources Information Center

    Stalheim-Smith, Ann; Fitch, Greg K.

    1985-01-01

    Describes a laboratory exercise which demonstrates qualitatively the specificity of the transport mechanism, including a consideration of the competitive inhibition, and the role of adenosine triphosphate (ATP) in active transport. The exercise, which can be completed in two to three hours by groups of four students, consistently produces reliable…

  17. MBAS (Methylene Blue Active Substances) and LAS (Linear Alkylbenzene Sulphonates) in Mediterranean coastal aerosols: Sources and transport processes

    NASA Astrophysics Data System (ADS)

    Becagli, S.; Ghedini, C.; Peeters, S.; Rottiers, A.; Traversi, R.; Udisti, R.; Chiari, M.; Jalba, A.; Despiau, S.; Dayan, U.; Temara, A.

    2011-12-01

    Methylene Blue Active Substances (MBAS) and Linear Alkylbenzene Sulphonates (LAS) concentrations, together with organic carbon and ions were measured in atmospheric coastal aerosols in the NW Mediterranean Basin. Previous studies have suggested that the presence of surfactants in coastal aerosols may result in vegetation damage without specifically detecting or quantifying these surfactants. Coastal aerosols were collected at a remote site (Porquerolles Island-Var, France) and at a more anthropised site (San Rossore National Park-Tuscany, Italy). The chemical data were interpreted according to a comprehensive local meteorological analysis aiming to decipher the airborne source and transport processes of these classes of compounds. The LAS concentration (anthropogenic surfactants) was measured in the samples using LC-MS/MS, a specific analytical method. The values were compared with the MBAS concentration, determined by a non-specific analytical method. At Porquerolles, the MBAS concentration (103 ± 93 ng m -3) in the summer samples was significantly higher than in the winter samples. In contrast, LAS concentrations were rarely greater than in the blank filters. At San Rossore, the mean annual MBAS concentration (887 ± 473 ng m -3 in PM10) contributed about 10% to the total atmospheric particulate organic matter. LAS mean concentration in these same aerosol samples was 11.5 ± 10.5 ng m -3. A similar MBAS (529 ± 454 ng m -3) - LAS (7.1 ± 4.1 ng m -3 LAS) ratio of ˜75 was measured in the fine (PM2.5) aerosol fraction. No linear correlation was found between MBAS and LAS concentrations. At San Rossore site the variation of LAS concentrations was studied on a daily basis over a year. The LAS concentrations in the coarse fraction (PM10-2.5) were higher during strong sea storm conditions, characterized by strong air flow coming from the sea sector. These events, occurring with more intensity in winter, promoted the formation of primary marine aerosols containing LAS

  18. Transport processes in space plasmas

    SciTech Connect

    Birn, J.; Elphic, R.C.; Feldman, W.C.

    1997-08-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project represents a comprehensive research effort to study plasma and field transport processes relevant for solar-terrestrial interaction, involving the solar wind and imbedded magnetic field and plasma structures, the bow shock of the Earth`s magnetosphere and associated waves, the Earth`s magnetopause with imbedded flux rope structures and their connection with the Earth, plasma flow in the Earth`s magnetotail, and ionospheric beam/wave interactions. The focus of the work was on the interaction between plasma and magnetic and electric fields in the regions where different plasma populations exist adjacent to or superposed on each other. These are the regions of particularly dynamic plasma behavior, important for plasma and energy transport and rapid energy releases. The research addressed questions about how this interaction takes place, what waves, instabilities, and particle/field interactions are involved, how the penetration of plasma and energy through characteristic boundaries takes place, and how the characteristic properties of the plasmas and fields of the different populations influence each other on different spatial and temporal scales. These topics were investigated through combining efforts in the analysis of plasma and field data obtained through space missions with theory and computer simulations of the plasma behavior.

  19. Rotary kilns - transport phenomena and transport processes

    SciTech Connect

    Boateng, A.

    2008-01-15

    Rotary kilns and rotating industrial drying ovens are used for a wide variety of applications including processing raw minerals and feedstocks as well as heat-treating hazardous wastes. They are particularly critical in the manufacture of Portland cement. Their design and operation is critical to their efficient usage, which if done incorrectly can result in improperly treated materials and excessive, high fuel costs. This book treats all engineering aspects of rotary kilns, including thermal and fluid principles involved in their operation, as well as how to properly design an engineering process that uses rotary kilns. Chapter 1: The Rotary Kiln Evolution and Phenomenon Chapter 2: Basic Description of Rotary Kiln Operation Chapter 3: Freeboard Aerodynamic Phenomena Chapter 4: Granular Flows in Rotary Kilns Chapter 5: Mixing and Segregation Chapter 6: Combustion and Flame - includes section on types of fuels used in rotary kilns, coal types, ranking and analysis, petroleum coke combustion, scrap tire combustion, pulverized fuel (coal/coke) firing in kilns, pulverized fuel delivery and firing systems. Chapter 7: Freeboard Heat Transfer Chapter 8: Heat Transfer Processes in the Rotary Kiln Bed Chapter 9: Mass and Energy Balance Chapter 10: Rotary Kiln Minerals Process Applications.

  20. A Combined Impact-Process Evaluation of a Program Promoting Active Transport to School: Understanding the Factors That Shaped Program Effectiveness

    PubMed Central

    Crawford, S.; Garrard, J.

    2013-01-01

    This mixed methods study was a comprehensive impact-process evaluation of the Ride2School program in metropolitan and regional areas in Victoria, Australia. The program aimed to promote transport to school for primary school children. Qualitative and quantitative data were collected at baseline and followup from two primary schools involved in the pilot phase of the program and two matched comparison schools, and a further 13 primary schools that participated in the implementation phase of the program. Classroom surveys, structured and unstructured observations, and interviews with Ride2School program staff were used to evaluate the pilot program. For the 13 schools in the second phase of the program, parents and students completed questionnaires at baseline (N = 889) and followup (N = 761). Based on the quantitative data, there was little evidence of an overall increase in active transport to school across participating schools, although impacts varied among individual schools. Qualitative data in the form of observations, interviews, and focus group discussions with students, school staff, and program staff provided insight into the reasons for variable program impacts. This paper highlights the benefits of undertaking a mixed methods approach to evaluating active transport to school programs that enables both measurement and understanding of program impacts. PMID:23606865

  1. A replacement of the active-site aspartic acid residue 293 in mouse cathepsin D affects its intracellular stability, processing and transport in HEK-293 cells.

    PubMed Central

    Partanen, Sanna; Storch, Stephan; Löffler, Hans-Gerhard; Hasilik, Andrej; Tyynelä, Jaana; Braulke, Thomas

    2003-01-01

    The substitution of an active-site aspartic acid residue by asparagine in the lysosomal protease cathepsin D (CTSD) results in a loss of enzyme activity and severe cerebrocortical atrophy in a novel form of neuronal ceroid lipofuscinosis in sheep [Tyynelä, Sohar, Sleat, Gin, Donnelly, Baumann, Haltia and Lobel (2000) EMBO J. 19, 2786-2792]. In the present study we have introduced the corresponding mutation by replacing aspartic acid residue 293 with asparagine (D293N) into the mouse CTSD cDNA to analyse its effect on synthesis, transport and stability in transfected HEK-293 cells. The complete inactivation of mutant D293N mouse CTSD was confirmed by a newly developed fluorimetric quantification system. Moreover, in the heterologous overexpression systems used, mutant D293N mouse CTSD was apparently unstable and proteolytically modified during early steps of the secretory pathway, resulting in a loss of mass by about 1 kDa. In the affected sheep, the endogenous mutant enzyme was stable but also showed the shift in its molecular mass. In HEK-293 cells, the transport of the mutant D293N mouse CTSD to the lysosome was delayed and associated with a low secretion rate compared with wild-type CTSD. These data suggest that the mutation may result in a conformational change which affects stability, processing and transport of the enzyme. PMID:12350228

  2. Nitrate transport in cucumber leaves is an inducible process involving an increase in plasma membrane H+-ATPase activity and abundance

    PubMed Central

    2012-01-01

    Background The mechanisms by which nitrate is transported into the roots have been characterized both at physiological and molecular levels. It has been demonstrated that nitrate is taken up in an energy-dependent way by a four-component uptake machinery involving high- and low- affinity transport systems. In contrast very little is known about the physiology of nitrate transport towards different plant tissues and in particular at the leaf level. Results The mechanism of nitrate uptake in leaves of cucumber (Cucumis sativus L. cv. Chinese long) plants was studied and compared with that of the root. Net nitrate uptake by roots of nitrate-depleted cucumber plants proved to be substrate-inducible and biphasic showing a saturable kinetics with a clear linear non saturable component at an anion concentration higher than 2 mM. Nitrate uptake by leaf discs of cucumber plants showed some similarities with that operating in the roots (e.g. electrogenic H+ dependence via involvement of proton pump, a certain degree of induction). However, it did not exhibit typical biphasic kinetics and was characterized by a higher Km with values out of the range usually recorded in roots of several different plant species. The quantity and activity of plasma membrane (PM) H+-ATPase of the vesicles isolated from leaf tissues of nitrate-treated plants for 12 h (peak of nitrate foliar uptake rate) increased with respect to that observed in the vesicles isolated from N-deprived control plants, thus suggesting an involvement of this enzyme in the leaf nitrate uptake process similar to that described in roots. Molecular analyses suggest the involvement of a specific isoform of PM H+-ATPase (CsHA1) and NRT2 transporter (CsNRT2) in root nitrate uptake. At the leaf level, nitrate treatment modulated the expression of CsHA2, highlighting a main putative role of this isogene in the process. Conclusions Obtained results provide for the first time evidence that a saturable and substrate

  3. Interaction of Hydraulic and Geotechnical Processes, and Sediment Transport in Controlling Channel Morphology in an Active Meander Bend

    NASA Astrophysics Data System (ADS)

    Simon, A.; Kuhnle, R.

    2004-12-01

    Evolution of meanders in incised alluvial channels is controlled by interactions between hydraulic forces acting on the bed and bank toe, and gravitational forces acting on in situ bank material. Vertical and lateral accretion of point bars lead to re-direction of flows in a downvalley direction that impinge on bank-toe surfaces causing undercutting, steepening and ultimate failure of the bank mass by gravity. The processes and forms inherent in incised meanders have been studied at an actively evolving meander bend on Goodwin Creek, Mississippi since 1996. Periodic surveys dating from 1977 to 1996 coupled with the dating of woody vegetation growing on the channel banks and bars were used to determine a migration rate of about 0.5 m/y since the mid-1960s. Up to 28 repetitive surveys were conducted at each of 10 monumented cross sections between 1996 and 2003 over an 82 m-long reach. Over the seven years of monitoring, 894 m3 of bank materials have been eroded from the reach while 436 m3 of sediment have been deposited on the bed and bar. Mean annual sediment concentrations have been essentially stable since the percent of cultivated land in the basin stabilized in the early 1990s. Migration of the outside bend by mass-wasting and toe removal of failed material has been matched by commensurate lateral accretion of point bars. Existing point bars grow vertically at a rate of about 5 cm/yr and now support establishing woody vegetation. Aggradation on the channel bed and lateral channel migration by bar accretion and opposite-bank retreat results in net erosion of all sediment but a net deposition of hydraulically-controlled sands and gravels. The erosion represents series of bank-failure episodes with subsequent removal of failed material by stormflow. A direct correlation between volumes of bar accretion and opposite-side bank erosion was developed, thus establishing a link between hydraulic and geotechnical processes. Peak-flow water-surface slopes increase with

  4. Transport Processes in Dendritic Crystallization

    NASA Technical Reports Server (NTRS)

    Glicksman, M. E.

    1984-01-01

    Free dentritic growth refers to the unconstrained development of crystals within a supercooled melt, which is the classical dendrite problem. The development of theoretical understanding of dendritic growth and its experimental status is sketched showing that transport theory and interfacial thermodynamics (capillarity theory) are insufficient ingredients to develop a truly predictive model of dendrite formation. The convenient, but incorrect, notion of maximum velocity was used for many years to estimate the behavior of dendritic transformations until supplanted by modern dynamic stability theory. The proper combinations of transport theory and morphological stability seem to be able to predict the salient aspects of dendritic growth, especially in the neighborhood of the tip.

  5. Regulators of Slc4 bicarbonate transporter activity

    PubMed Central

    Thornell, Ian M.; Bevensee, Mark O.

    2015-01-01

    The Slc4 family of transporters is comprised of anion exchangers (AE1-4), Na+-coupled bicarbonate transporters (NCBTs) including electrogenic Na/bicarbonate cotransporters (NBCe1 and NBCe2), electroneutral Na/bicarbonate cotransporters (NBCn1 and NBCn2), and the electroneutral Na-driven Cl-bicarbonate exchanger (NDCBE), as well as a borate transporter (BTR1). These transporters regulate intracellular pH (pHi) and contribute to steady-state pHi, but are also involved in other physiological processes including CO2 carriage by red blood cells and solute secretion/reabsorption across epithelia. Acid-base transporters function as either acid extruders or acid loaders, with the Slc4 proteins moving HCO−3 either into or out of cells. According to results from both molecular and functional studies, multiple Slc4 proteins and/or associated splice variants with similar expected effects on pHi are often found in the same tissue or cell. Such apparent redundancy is likely to be physiologically important. In addition to regulating pHi, a HCO−3 transporter contributes to a cell's ability to fine tune the intracellular regulation of the cotransported/exchanged ion(s) (e.g., Na+ or Cl−). In addition, functionally similar transporters or splice variants with different regulatory profiles will optimize pH physiology and solute transport under various conditions or within subcellular domains. Such optimization will depend on activated signaling pathways and transporter expression profiles. In this review, we will summarize and discuss both well-known and more recently identified regulators of the Slc4 proteins. Some of these regulators include traditional second messengers, lipids, binding proteins, autoregulatory domains, and less conventional regulators. The material presented will provide insight into the diversity and physiological significance of multiple members within the Slc4 gene family. PMID:26124722

  6. Saturn Plasma Sources and Associated Transport Processes

    NASA Astrophysics Data System (ADS)

    Blanc, M.; Andrews, D. J.; Coates, A. J.; Hamilton, D. C.; Jackman, C. M.; Jia, X.; Kotova, A.; Morooka, M.; Smith, H. T.; Westlake, J. H.

    2015-10-01

    This article reviews the different sources of plasma for Saturn's magnetosphere, as they are known essentially from the scientific results of the Cassini-Huygens mission to Saturn and Titan. At low and medium energies, the main plasma source is the H2O cloud produced by the "geyser" activity of the small satellite Enceladus. Impact ionization of this cloud occurs to produce on the order of 100 kg/s of fresh plasma, a source which dominates all the other ones: Titan (which produces much less plasma than anticipated before the Cassini mission), the rings, the solar wind (a poorly known source due to the lack of quantitative knowledge of the degree of coupling between the solar wind and Saturn's magnetosphere), and the ionosphere. At higher energies, energetic particles are produced by energy diffusion and acceleration of lower energy plasma produced by the interchange instabilities induced by the rapid rotation of Saturn, and possibly, for the highest energy range, by contributions from the CRAND process acting inside Saturn's magnetosphere. Discussion of the transport and acceleration processes acting on these plasma sources shows the importance of rotation-induced radial transport and energization of the plasma, and also shows how much the unexpected planetary modulation of essentially all plasma parameters of Saturn's magnetosphere remains an unexplained mystery.

  7. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  8. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much_lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  9. Common folds and transport mechanisms of secondary active transporters.

    PubMed

    Shi, Yigong

    2013-01-01

    Secondary active transporters exploit the electrochemical potential of solutes to shuttle specific substrate molecules across biological membranes, usually against their concentration gradient. Transporters of different functional families with little sequence similarity have repeatedly been found to exhibit similar folds, exemplified by the MFS, LeuT, and NhaA folds. Observations of multiple conformational states of the same transporter, represented by the LeuT superfamily members Mhp1, AdiC, vSGLT, and LeuT, led to proposals that structural changes are associated with substrate binding and transport. Despite recent biochemical and structural advances, our understanding of substrate recognition and energy coupling is rather preliminary. This review focuses on the common folds and shared transport mechanisms of secondary active transporters. Available structural information generally supports the alternating access model for substrate transport, with variations and extensions made by emerging structural, biochemical, and computational evidence.

  10. Respiratory fluid mechanics and transport processes.

    PubMed

    Grotberg, J B

    2001-01-01

    The field of respiratory flow and transport has experienced significant research activity over the past several years. Important contributions to the knowledge base come from pulmonary and critical care medicine, surgery, physiology, environmental health sciences, biophysics, and engineering. Several disciplines within engineering have strong and historical ties to respiration including mechanical, chemical, civil/environmental, aerospace and, of course, biomedical engineering. This review draws from a wide variety of scientific literature that reflects the diverse constituency and audience that respiratory science has developed. The subject areas covered include nasal flow and transport, airway gas flow, alternative modes of ventilation, nonrespiratory gas transport, aerosol transport, airway stability, mucus transport, pulmonary acoustics, surfactant dynamics and delivery, and pleural liquid flow. Within each area are a number of subtopics whose exploration can provide the opportunity of both depth and breadth for the interested reader.

  11. Charge Transport Processes in Molecular Junctions

    NASA Astrophysics Data System (ADS)

    Smith, Christopher Eugene

    . Using quantum-based calculations, we modeled 'p-type' polaron transport through oligophenylenethiophene (OPTI) wires and assigned transport activation energies to specific modes of nuclear motion. We also show control over 'n-type', LUMO-mediated transport in short ( 2 nm) redox-active perylenediimide (PDI) SAMs bound to contacts through isocyano linkers. By changing the contact work function (φ) and temperature, we were able to verify thermally-assisted LUMO transport. Transition voltage spectroscopy and the single level model was employed to fit the experimental I-V curves and extract the electronic coupling (epsilon) and the EF-LUMO offset (epsilonl). It was found that epsilonl does not change with φ (LUMO pinning), while Gamma changes with both φ and temperature. Further, the PDI SAMs could be reversibly chemically gated to modulate the transport. These results help advance our understanding of transport behavior in semiconducting molecular thin films, and open opportunities to engineer improved electronic functionality into molecular devices.

  12. Transport processes in the middle atmosphere: Reflections after MAP

    NASA Technical Reports Server (NTRS)

    Grose, W. L.

    1989-01-01

    The Middle Atmosphere Program (MAP) has provided a focus for considerable research on atmospherical radiative, chemical, and dynamical processes and the mutual coupling among these processes. In particular, major advances have occurred in the understanding of constituent transport as a result of near-global measurements obtained during MAP from several satellite based instruments (e.g., LIMS, SAMS, SAGE, and SSU among others). Using selected portions of these data, the development is reviewed of progress in understanding transport processes with special emphasis on dynamically active periods. Examples are presented which demonstrate coupling between chemistry and dynamics. In addition to the constituent data, the use is reviewed of Ertel's potential vorticity, inferred from satellite temperature data, as a diagnostic for interpreting transport phenomena. Finally, the use is briefly illustrated of 3-D model simulations, in conjunction with the satellite data, for providing additional insight into fundamental transport mechanisms.

  13. Modeling of active transmembrane transport in a mixture theory framework.

    PubMed

    Ateshian, Gerard A; Morrison, Barclay; Hung, Clark T

    2010-05-01

    This study formulates governing equations for active transport across semi-permeable membranes within the framework of the theory of mixtures. In mixture theory, which models the interactions of any number of fluid and solid constituents, a supply term appears in the conservation of linear momentum to describe momentum exchanges among the constituents. In past applications, this momentum supply was used to model frictional interactions only, thereby describing passive transport processes. In this study, it is shown that active transport processes, which impart momentum to solutes or solvent, may also be incorporated in this term. By projecting the equation of conservation of linear momentum along the normal to the membrane, a jump condition is formulated for the mechano-electrochemical potential of fluid constituents which is generally applicable to nonequilibrium processes involving active transport. The resulting relations are simple and easy to use, and address an important need in the membrane transport literature.

  14. Gravity-dependent transport in industrial processes

    NASA Technical Reports Server (NTRS)

    Ostrach, Simon; Kamotani, Yasuhiro

    1994-01-01

    Gravity-dependent transport phenomena in various industrial processes are investigated in order to address a broader range of microgravity phenomena and to develop new applications of microgravity. A number of important topics are identified and analyzed in detail. The present article describes results on coating flow, zeolite growth, and rotating electrochemical system.

  15. Coupled transport processes in semipermeable media

    SciTech Connect

    Jacobsen, J.S.; Carnahan, C.L.

    1990-04-01

    A numerical simulator has been developed to investigate the effects of coupled processes on heat and mass transport in semipermeable media. The governing equations on which the simulator is based were derived using the thermodynamics of irreversible processes. The equations are nonlinear and have been solved numerically using the n-dimensional Newton's method. As an example of an application, the numerical simulator has been used to investigate heat and solute transport in the vicinity of a heat source buried in a saturated clay-like medium, in part to study solute transport in bentonite packing material surrounding a nuclear waste canister. The coupled processes considered were thermal filtration, thermal osmosis, chemical osmosis and ultrafiltration. In the simulations, heat transport by coupled processes was negligible compared to heat conduction, but pressure and solute migration were affected. Solute migration was retarded relative to the uncoupled case when only chemical osmosis was considered. When both chemical osmosis and thermal osmosis were included, solute migration was enhanced. 18 refs., 20 figs.

  16. Transport processes near coastal ocean outfalls

    USGS Publications Warehouse

    Noble, M.A.; Sherwood, C.R.; Lee, Hooi-Ling; Xu, Jie; Dartnell, P.; Robertson, G.; Martini, M.

    2001-01-01

    The central Southern California Bight is an urbanized coastal ocean where complex topography and largescale atmospheric and oceanographic forcing has led to numerous sediment-distribution patterns. Two large embayments, Santa Monica and San Pedro Bays, are connected by the short, very narrow shelf off the Palos Verdes peninsula. Ocean-sewage outfalls are located in the middle of Santa Monica Bay, on the Palos Verdes shelf and at the southeastern edge of San Pedro Bay. In 1992, the US Geological Survey, together with allied agencies, began a series of programs to determine the dominant processes that transport sediment and associated pollutants near the three ocean outfalls. As part of these programs, arrays of instrumented moorings that monitor currents, waves, water clarity, water density and collect resuspended materials were deployed on the continental shelf and slope information was also collected on the sediment and contaminant distributions in the region. The data and models developed for the Palos Verdes shelf suggest that the large reservoir of DDT/DDE in the coastal ocean sediments will continue to be exhumed and transported along the shelf for a long time. On the Santa Monica shelf, very large internal waves, or bores, are generated at the shelf break. The near-bottom currents associated with these waves sweep sediments and the associated contaminants from the shelf onto the continental slope. A new program underway on the San Pedro shelf will determine if water and contaminants from a nearby ocean outfall are transported to the local beaches by coastal ocean processes. The large variety of processes found that transport sediments and contaminants in this small region of the continental margin suggest that in regions with complex topography, local processes change markedly over small spatial scales. One cannot necessarily infer that the dominant transport processes will be similar even in adjacent regions.

  17. Gravity-Dependent Transport in Industrial Processes

    NASA Technical Reports Server (NTRS)

    Ostrach, Simon; Kamotani, Yasuhiro

    1996-01-01

    Gravity dependent transport phenomena in various industrial processes are investigated in order to indicate new directions for micro-gravity research that enhance the commercial success of the space program. The present article describes the commercialization possibilities of such topics associated with physicochemical transport phenomena. The topics are: coating flow, rotating electrochemical system, and convection in low Plandtl number fluids. The present study is directed to understand these phenomena, and to develop a knowledge base for their applications with emphasis to a micro-gravity environment.

  18. (Fission product transport processes in reactor accidents)

    SciTech Connect

    Hodge, S.A.; Beahm, E.C.; Kress, T.S.; Malinauskas, A.P.

    1989-06-14

    The purpose of this trip was to participate in and to hold informal discussions with other participants in the International Centre for Heat and Mass Transfer (ICHMT) International Seminar on Fission Product Transport Processes held at Dubrovnik, Yugoslavia, during the week of May 22--26, 1989. There were 129 participants from 20 countries at the Seminar. The travelers delivered two invited lectures and presented four invited papers based upon NRC-sponsored work at Oak Ridge National Laboratory. One of the travelers also served as Chairman of the Session entitled Transport Phenomena in the Reactor Coolant System'' and appeared as a Panelist in the Closing Session of the Seminar.

  19. Mesoscopic Modeling of Reactive Transport Processes

    NASA Astrophysics Data System (ADS)

    Kang, Q.; Chen, L.; Deng, H.

    2012-12-01

    Reactive transport processes involving precipitation and/or dissolution are pervasive in geochemical, biological and engineered systems. Typical examples include self-assembled patterns such as Liesegang rings or bands, cones of stalactites in limestones caves, biofilm growth in aqueous environment, formation of mineral deposits in boilers and heat exchangers, uptake of toxic metal ions from polluted water by calcium carbonate, and mineral trapping of CO2. Compared to experimental studies, a numerical approach enables a systematic study of the reaction kinetics, mass transport, and mechanisms of nucleation and crystal growth, and hence provides a detailed description of reactive transport processes. In this study, we enhance a previously developed lattice Boltzmann pore-scale model by taking into account the nucleation process, and develop a mesoscopic approach to simulate reactive transport processes involving precipitation and/or dissolution of solid phases. The model is then used to simulate the formation of Liesegang precipitation patterns and investigate the effects of gel on the morphology of the precipitates. It is shown that this model can capture the porous structures of the precipitates and can account for the effects of the gel concentration and material. A wide range of precipitation patterns is predicted under different gel concentrations, including regular bands, treelike patterns, and for the first time with numerical models, transition patterns from regular bands to treelike patterns. The model is also applied to study the effect of secondary precipitate on the dissolution of primary mineral. Several types of dissolution and precipitation processes are identified based on the morphology and structures of the precipitates and on the extent to which the precipitates affect the dissolution of the primary mineral. Finally the model is applied to study the formation of pseudomorph. It is demonstrated for the first time by numerical simulation that a

  20. Riparian seed dispersal: transport and depositional processes

    NASA Astrophysics Data System (ADS)

    Cunnings, A.; Johnson, E. A.; Martin, Y. E.

    2012-04-01

    Riparian tree population dynamics are linked to the physical processes controlled by the hydrogeomorphic setting. In particular, fluvial seed dispersal is influenced by a combination of factors including the hydrology, fluvial geomorphology, and seed dispersal traits. This study examines the influence of stream flow patterns on the transportation and deposition of buoyant seeds by applying a one dimensional transport model. Conceptually, the model separates the stream into two components: the main channel and transient storage /deposition zones. The hydrologic processes are governed by an advection-dispersion equation and numerically solved using the Crank-Nicolson method. Additional terms in the equation allow for model variation in the flow regime (lateral inflow and outflow) and the incorporation of a transient storage/deposition component where seeds may be detained. The model parameters are based on a bedrock-gravel bed river with pool-riffle morphology where we conducted field experimentation in Coastal Northern California. The riparian zone of the study reach is inhabited by White Alder (Alnus rhombifolia) which disperses buoyant seeds in late winter/early spring coinciding with the latter part of the wet, Mediterranean climate. Artificial seeds with similar characteristic traits of buoyancy, density and Bond Number to White Alder seeds were used to quantify transport times and identify storage areas. The model output captures a greater number of seeds during a receding hydrograph due to the increase in transient storage. Typically, this is found in shallow stream margins where the flow is divergent such as areas with back-eddies. In the field, this is associated with the ends of gravel bars or riffles where flow expansion causes secondary flows. The results demonstrate the importance of transient storage for seed transport and depositional processes and emphasize the need for improved measurement techniques, in lieu of empirical coefficients, to advance the

  1. Regulation & Development of Membrane Transport Processes.

    DTIC Science & Technology

    1985-05-15

    Laboratory, Oak Ridge, Tennessee DAVID W. PLMPLIN Department of Anatomy, University of Maryland School of Medicine, Baltimore, Maryland MARILYN D. RESH...Muscle 265 Douglas M. Fambrough, Barry A. Wolitzky, and David W. Pumplin Index 283 REGULATION AND DEVELOPMENT OF MEMBRANE TRANSPORT PROCESSES 77, II PART 1...243 (Cell Physiol. 12). C 124-C132. 16. Huang. C. C.. Tsai. C. M.. and Canellakis, E. S. (1973) Bochiom. Biophys. Acta. 332, 59-68. 17. Hume . S. and

  2. Coupled transport processes in semipermeable media

    SciTech Connect

    Carnahan, C.L.; Jacobsen, J.S.

    1990-04-01

    The thermodynamics of irreversible processes (TTIP) is used to derive governing equations and phenomenological equations for transport processes and chemical reactions in water-saturated semipermeable media. TTIP is based on three fundamental postulates. The first postulate, the assumption of local equilibrium, allows the formulation of balance equations for entropy. These equations are the bases for the derivation of governing equations for the thermodynamic variables, temperature, pressure, and composition. The governing equations involve vector fluxes of heat and mass and scalar rates of chemical reactions; in accordance with the second postulate of TTIP, these fluxes and rates are related, respectively, to all scalar driving forces (gradients of thermodynamic variables) acting within the system. The third postulate of TTIP states equality (the Onsager reciprocal relations) between certain of the phenomenological coefficients relating forces and fluxes. The description by TTIP of a system undergoing irreversible processes allows consideration of coupled transport processes such as thermal osmosis, chemical osmosis, and ultrafiltration. The coupled processes can make significant contributions to flows of mass and energy in slightly permeable, permselective geological materials such as clays and shales.

  3. The transport properties of activated carbon fibers

    SciTech Connect

    di Vittorio, S.L. . Dept. of Materials Science and Engineering); Dresselhaus, M.S. . Dept. of Electrical Engineering and Computer Science Massachusetts Inst. of Tech., Cambridge, MA . Dept. of Physics); Endo, M. . Dept. of Electrical Engineering); Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons. 19 refs., 4 figs.

  4. The Transport Properties of Activated Carbon Fibers

    DOE R&D Accomplishments Database

    di Vittorio, S. L.; Dresselhaus, M. S.; Endo, M.; Issi, J-P.; Piraux, L.

    1990-07-01

    The transport properties of activated isotropic pitch-based carbon fibers with surface area 1000 m{sup 2}/g have been investigated. We report preliminary results on the electrical conductivity, the magnetoresistance, the thermal conductivity and the thermopower of these fibers as a function of temperature. Comparisons are made to transport properties of other disordered carbons.

  5. Conditions and processes affecting radionuclide transport

    USGS Publications Warehouse

    Simmons, Ardyth M.; Neymark, Leonid A.

    2012-01-01

    Understanding of unsaturated-zone transport is based on laboratory and field-scale experiments. Fractures provide advective transport pathways. Sorption and matrix diffusion may contribute to retardation of radionuclides. Conversely, sorption onto mobile colloids may enhance radionuclide transport.

  6. Active braze process

    SciTech Connect

    Levine, I.L.; Pike, R.A.

    1990-11-02

    Active metal bonding using Cusil (silver-copper) braze alloys is a well established method used at GE Neutron Devices (GEND) for bonding metal to metal, metal to ceramics, and ceramics to ceramics. However, there are many instances in which using a silver alloy for bonding is undesirable (e.g., in vacuum tube envelopes, or where sequential braze steps at different temperatures are required to complete an assembly). The Material and Processes Laboratory at GEND has discovered a new method of active brazing with non-silver alloys which has proved especially successful in ceramic-to-ceramic joints. This method has the added advantage of eliminating several steps which are required in conventional bonding techniques. 2 figs., 10 tabs.

  7. Space transportation main engine cycle assessment process

    NASA Technical Reports Server (NTRS)

    Mcconnaughey, H. V.; Lyles, G. M.

    1991-01-01

    The Advanced Launch System (ALS) program selection process for a space transportation main engine (STME) power cycle is described in terms of the methodology employed. Low cost, robustness, and high reliability are the primary parameters for engine choice, suggesting simplicity of design and efficient fabrication methods as the crucial characteristics. An evaluation methodology is developed based on the Pugh (1981) process and the King (1989) matrices. The cycle configurations considered are the gas generator (GG), the closed expander, and the open expander. The cycle assessment team determined that the GG cycle is favored by most cycle discriminators, based on an assessment of the characteristics in terms of ALS goals. The lower development risk of the GG-cycle STME is consistent with the goals of the ALS program in terms of reliability and cost efficiency.

  8. Chill Down Process of Hydrogen Transport Pipelines

    NASA Technical Reports Server (NTRS)

    Mei, Renwei; Klausner, James

    2006-01-01

    A pseudo-steady model has been developed to predict the chilldown history of pipe wall temperature in the horizontal transport pipeline for cryogenic fluids. A new film boiling heat transfer model is developed by incorporating the stratified flow structure for cryogenic chilldown. A modified nucleate boiling heat transfer correlation for cryogenic chilldown process inside a horizontal pipe is proposed. The efficacy of the correlations is assessed by comparing the model predictions with measured values of wall temperature in several azimuthal positions in a well controlled experiment by Chung et al. (2004). The computed pipe wall temperature histories match well with the measured results. The present model captures important features of thermal interaction between the pipe wall and the cryogenic fluid, provides a simple and robust platform for predicting pipe wall chilldown history in long horizontal pipe at relatively low computational cost, and builds a foundation to incorporate the two-phase hydrodynamic interaction in the chilldown process.

  9. Ratchet transport powered by chiral active particles

    PubMed Central

    Ai, Bao-quan

    2016-01-01

    We numerically investigate the ratchet transport of mixtures of active and passive particles in a transversal asymmetric channel. A big passive particle is immersed in a ‘sea’ of active particles. Due to the chirality of active particles, the longitudinal directed transport is induced by the transversal asymmetry. For the active particles, the chirality completely determines the direction of the ratchet transport, the counterclockwise and clockwise particles move to the opposite directions and can be separated. However, for the passive particle, the transport behavior becomes complicated, the direction is determined by competitions among the chirality, the self-propulsion speed, and the packing fraction. Interestingly, within certain parameters, the passive particle moves to the left, while active particles move to the right. In addition, there exist optimal parameters (the chirality, the height of the barrier, the self-propulsion speed and the packing fraction) at which the rectified efficiency takes its maximal value. Our findings could be used for the experimental pursuit of the ratchet transport powered by chiral active particles. PMID:26795952

  10. Chill activation of compatible solute transporters in Corynebacterium glutamicum at the level of transport activity.

    PubMed

    Ozcan, Nuran; Krämer, Reinhard; Morbach, Susanne

    2005-07-01

    The gram-positive soil bacterium Corynebacterium glutamicum harbors four osmoregulated secondary uptake systems for compatible solutes, BetP, EctP, LcoP, and ProP. When reconstituted in proteoliposomes, BetP was shown to sense hyperosmotic conditions via the increase in luminal K(+) and to respond by instant activation. To study further putative ways of stimulus perception and signal transduction, we have investigated the responses of EctP, LcoP, and BetP, all belonging to the betaine-carnitine-choline transporter family, to chill stress at the level of activity. When fully activated by hyperosmotic stress, they showed the expected increase of activity at increasing temperature. In the absence of osmotic stress, EctP was not activated by chill and LcoP to only a very low extent, whereas BetP was significantly stimulated at low temperature. BetP was maximally activated at 10 degrees C, reaching the same transport rate as that observed under hyperosmotic conditions at this temperature. A role of cytoplasmic K(+) in chill-dependent activation of BetP was ruled out, since (i) the cytoplasmic K(+) concentration did not change significantly at lower temperatures and (ii) a mutant BetP lacking the C-terminal 25 amino acids, which was previously shown to have lost the ability to be activated by luminal K(+), was fully competent in chill sensing. When heterologously expressed in Escherichia coli, BetP did not respond to chill stress. This may indicate that the membrane in which BetP is inserted plays an important role in chill activation and thus in signal transduction by BetP, different from the previously established K(+)-mediated process.

  11. Stochastic steps in secondary active sugar transport.

    PubMed

    Adelman, Joshua L; Ghezzi, Chiara; Bisignano, Paola; Loo, Donald D F; Choe, Seungho; Abramson, Jeff; Rosenberg, John M; Wright, Ernest M; Grabe, Michael

    2016-07-05

    Secondary active transporters, such as those that adopt the leucine-transporter fold, are found in all domains of life, and they have the unique capability of harnessing the energy stored in ion gradients to accumulate small molecules essential for life as well as expel toxic and harmful compounds. How these proteins couple ion binding and transport to the concomitant flow of substrates is a fundamental structural and biophysical question that is beginning to be answered at the atomistic level with the advent of high-resolution structures of transporters in different structural states. Nonetheless, the dynamic character of the transporters, such as ion/substrate binding order and how binding triggers conformational change, is not revealed from static structures, yet it is critical to understanding their function. Here, we report a series of molecular simulations carried out on the sugar transporter vSGLT that lend insight into how substrate and ions are released from the inward-facing state of the transporter. Our simulations reveal that the order of release is stochastic. Functional experiments were designed to test this prediction on the human homolog, hSGLT1, and we also found that cytoplasmic release is not ordered, but we confirmed that substrate and ion binding from the extracellular space is ordered. Our findings unify conflicting published results concerning cytoplasmic release of ions and substrate and hint at the possibility that other transporters in the superfamily may lack coordination between ions and substrate in the inward-facing state.

  12. Stochastic steps in secondary active sugar transport

    PubMed Central

    Adelman, Joshua L.; Ghezzi, Chiara; Bisignano, Paola; Loo, Donald D. F.; Choe, Seungho; Abramson, Jeff; Rosenberg, John M.; Wright, Ernest M.; Grabe, Michael

    2016-01-01

    Secondary active transporters, such as those that adopt the leucine-transporter fold, are found in all domains of life, and they have the unique capability of harnessing the energy stored in ion gradients to accumulate small molecules essential for life as well as expel toxic and harmful compounds. How these proteins couple ion binding and transport to the concomitant flow of substrates is a fundamental structural and biophysical question that is beginning to be answered at the atomistic level with the advent of high-resolution structures of transporters in different structural states. Nonetheless, the dynamic character of the transporters, such as ion/substrate binding order and how binding triggers conformational change, is not revealed from static structures, yet it is critical to understanding their function. Here, we report a series of molecular simulations carried out on the sugar transporter vSGLT that lend insight into how substrate and ions are released from the inward-facing state of the transporter. Our simulations reveal that the order of release is stochastic. Functional experiments were designed to test this prediction on the human homolog, hSGLT1, and we also found that cytoplasmic release is not ordered, but we confirmed that substrate and ion binding from the extracellular space is ordered. Our findings unify conflicting published results concerning cytoplasmic release of ions and substrate and hint at the possibility that other transporters in the superfamily may lack coordination between ions and substrate in the inward-facing state. PMID:27325773

  13. Development of novel active transport membrande devices

    SciTech Connect

    Laciak, D.V.

    1994-11-01

    Air Products has undertaken a research program to fabricate and evaluate gas separation membranes based upon promising ``active-transport`` (AT) materials recently developed in our laboratories. Active Transport materials are ionic polymers and molten salts which undergo reversible interaction or reaction with ammonia and carbon dioxide. The materials are useful for separating these gases from mixtures with hydrogen. Moreover, AT membranes have the unique property of possessing high permeability towards ammnonia and carbon dioxide but low permeability towards hydrogen and can thus be used to permeate these components from a gas stream while retaining hydrogen at high pressure.

  14. Measurement of action spectra of light-activated processes

    NASA Astrophysics Data System (ADS)

    Ross, Justin; Zvyagin, Andrei V.; Heckenberg, Norman R.; Upcroft, Jacqui; Upcroft, Peter; Rubinsztein-Dunlop, Halina H.

    2006-01-01

    We report on a new experimental technique suitable for measurement of light-activated processes, such as fluorophore transport. The usefulness of this technique is derived from its capacity to decouple the imaging and activation processes, allowing fluorescent imaging of fluorophore transport at a convenient activation wavelength. We demonstrate the efficiency of this new technique in determination of the action spectrum of the light mediated transport of rhodamine 123 into the parasitic protozoan Giardia duodenalis.

  15. Health Impacts of Active Transportation in Europe

    PubMed Central

    Rojas-Rueda, David; de Nazelle, Audrey; Andersen, Zorana J.; Braun-Fahrländer, Charlotte; Bruha, Jan; Bruhova-Foltynova, Hana; Desqueyroux, Hélène; Praznoczy, Corinne; Ragettli, Martina S.; Tainio, Marko; Nieuwenhuijsen, Mark J.

    2016-01-01

    Policies that stimulate active transportation (walking and bicycling) have been related to heath benefits. This study aims to assess the potential health risks and benefits of promoting active transportation for commuting populations (age groups 16–64) in six European cities. We conducted a health impact assessment using two scenarios: increased cycling and increased walking. The primary outcome measure was all-cause mortality related to changes in physical activity level, exposure to fine particulate matter air pollution with a diameter <2.5 μm, as well as traffic fatalities in the cities of Barcelona, Basel, Copenhagen, Paris, Prague, and Warsaw. All scenarios produced health benefits in the six cities. An increase in bicycle trips to 35% of all trips (as in Copenhagen) produced the highest benefits among the different scenarios analysed in Warsaw 113 (76–163) annual deaths avoided, Prague 61 (29–104), Barcelona 37 (24–56), Paris 37 (18–64) and Basel 5 (3–9). An increase in walking trips to 50% of all trips (as in Paris) resulted in 19 (3–42) deaths avoided annually in Warsaw, 11(3–21) in Prague, 6 (4–9) in Basel, 3 (2–6) in Copenhagen and 3 (2–4) in Barcelona. The scenarios would also reduce carbon dioxide emissions in the six cities by 1,139 to 26,423 (metric tonnes per year). Policies to promote active transportation may produce health benefits, but these depend of the existing characteristics of the cities. Increased collaboration between health practitioners, transport specialists and urban planners will help to introduce the health perspective in transport policies and promote active transportation. PMID:26930213

  16. Transport Processes from Mechanics: Minimal and Simplest Models

    NASA Astrophysics Data System (ADS)

    Bunimovich, Leonid A.; Grigo, Alexander

    2017-02-01

    We review the current state of a fundamental problem of rigorous derivation of transport processes in classical statistical mechanics from classical mechanics. Such derivations for diffusion and momentum transport (viscosities) were obtained for minimal models of these processes involving one and two particles respectively. However, a minimal model which demonstrates heat conductivity contains three particles. Its rigorous analysis is currently out of reach for existing mathematical techniques. The gas of localized balls is widely accepted as a basis for a simplest model for derivation of Fourier's law. We suggest a modification of the localized balls gas and argue that this gas of localized activated balls is a good candidate to rigorously prove Fourier's law. In particular, hyperbolicity is derived for a reduced version of this model.

  17. Transport Processes from Mechanics: Minimal and Simplest Models

    NASA Astrophysics Data System (ADS)

    Bunimovich, Leonid A.; Grigo, Alexander

    2016-12-01

    We review the current state of a fundamental problem of rigorous derivation of transport processes in classical statistical mechanics from classical mechanics. Such derivations for diffusion and momentum transport (viscosities) were obtained for minimal models of these processes involving one and two particles respectively. However, a minimal model which demonstrates heat conductivity contains three particles. Its rigorous analysis is currently out of reach for existing mathematical techniques. The gas of localized balls is widely accepted as a basis for a simplest model for derivation of Fourier's law. We suggest a modification of the localized balls gas and argue that this gas of localized activated balls is a good candidate to rigorously prove Fourier's law. In particular, hyperbolicity is derived for a reduced version of this model.

  18. Fluid transport by active elastic membranes

    NASA Astrophysics Data System (ADS)

    Evans, Arthur A.; Lauga, Eric

    2011-09-01

    A flexible membrane deforming its shape in time can self-propel in a viscous fluid. Alternatively, if the membrane is anchored, its deformation will lead to fluid transport. Past work in this area focused on situations where the deformation kinematics of the membrane were prescribed. Here we consider models where the deformation of the membrane is not prescribed, but instead the membrane is internally forced. Both the time-varying membrane shape and the resulting fluid motion result then from a balance between prescribed internal active stresses, internal passive resistance, and external viscous stresses. We introduce two specific models for such active internal forcing: one where a distribution of active bending moments is prescribed, and one where active inclusions exert normal stresses on the membrane by pumping fluid through it. In each case, we asymptotically calculate the membrane shape and the fluid transport velocities for small forcing amplitudes, and recover our results using scaling analysis.

  19. Astrocytic GABA transporter activity modulates excitatory neurotransmission

    PubMed Central

    Boddum, Kim; Jensen, Thomas P.; Magloire, Vincent; Kristiansen, Uffe; Rusakov, Dmitri A.; Pavlov, Ivan; Walker, Matthew C.

    2016-01-01

    Astrocytes are ideally placed to detect and respond to network activity. They express ionotropic and metabotropic receptors, and can release gliotransmitters. Astrocytes also express transporters that regulate the extracellular concentration of neurotransmitters. Here we report a previously unrecognized role for the astrocytic GABA transporter, GAT-3. GAT-3 activity results in a rise in astrocytic Na+ concentrations and a consequent increase in astrocytic Ca2+ through Na+/Ca2+ exchange. This leads to the release of ATP/adenosine by astrocytes, which then diffusely inhibits neuronal glutamate release via activation of presynaptic adenosine receptors. Through this mechanism, increases in astrocytic GAT-3 activity due to GABA released from interneurons contribute to 'diffuse' heterosynaptic depression. This provides a mechanism for homeostatic regulation of excitatory transmission in the hippocampus. PMID:27886179

  20. Vadose Transport Processes in an Irrigated Forest

    NASA Astrophysics Data System (ADS)

    Seaman, J. C.; Vulava, V.; Aburime, S. A.

    2001-12-01

    A series of solute transport experiments using tritium as a conservative tracer were conducted in an irrigated upland forest watershed at the U.S. Department of Energy's Savannah River Site (SRS) located near Aiken, SC. The objective of the current study was to evaluate the processes controlling water movement within the vadose zone as influenced by irrigation and seasonal changes in precipitation and evapotranspiration. The moisture retention properties (matric potential) and unsaturated hydraulic conductivities were determined for the horizons comprising the dominant soil series within the study site using an Unsaturated Flow Apparatus (UFA; UFA Ventures Inc., Kennewick, WA). The field study site consisted of a series of monitoring clusters, each containing of a tube-type TDR system installed to a depth of 6 ft, suction lysimeters installed to depths of 2, 4 and 6ft, and tensiometers at 1, 2, 4, and 6ft. The first tracer experiment consisted of an application of 2.5" of labeled irrigation water in July followed by periodic monitoring over the next few months under normal rainfall conditions. The depth of tracer migration roughly corresponded to soil field capacity (FC). The soil volumetric water content had to exceed FC as determined by UFA, before significant downward movement occurred. The rate of migration was quite variable within the small study plot, approximately 0.25 acres. Despite the relative large tracer pulse, significant dispersion and dilution were observed over relatively shallow travel depths, i.e., 2 ft.

  1. Use of boundary fluxes when simulating solute transport with the MODFLOW ground-water transport process

    USGS Publications Warehouse

    Konikow, L.F.; Hornberger, G.Z.

    2003-01-01

    This report describes modifications to a U.S. Geological Survey (USGS) threedimensional solute-transport model (MODFLOWGWT), which is incorporated into the USGS MODFLOW ground-water model as the Ground- Water Transport (GWT) Process. The modifications improve the capability of MODFLOW-GWT to accurately simulate solute transport in simulations that represent a nonzero flux across an aquifer boundary. In such situations, the new Boundary Flux Package (BFLX) will allow the user flexibility to assign the flux to specific cell faces, although that flexibility is limited for certain types of fluxes (such as recharge and evapotranspiration, which can only be assigned to the top face if either is to be represented as a boundary flux). The approach is consistent with that used in the MODPATH model. The application of the BFLX Package was illustrated using a test case in which the Lake Package was active. The results using the BFLX Package showed noticeably higher magnitudes of velocity in the cells adjacent to the lake than previous results without the BFLX Package. Consequently, solute was transported slightly faster through the lake-aquifer system when the BFLX Package is active. However, the overall solute distributions did not differ greatly from simulations made without using the BFLX Package.

  2. Intrinsic and extrinsic negative regulators of nuclear protein transport processes

    PubMed Central

    Sekimoto, Toshihiro; Yoneda, Yoshihiro

    2012-01-01

    The nuclear–cytoplasmic protein transport is a critical process in cellular events. The identification of transport signals (nuclear localization signal and nuclear export signal) and their receptors has facilitated our understanding of this expanding field. Nuclear transport must be appropriately regulated to deliver proteins through the nuclear pore when their functions are required in the nucleus, and to export them into the cytoplasm when they are not needed in the nucleus. Altered nuclear transport processes have been observed in stressed cells, which would change gene expressions. Some viruses interfere with nuclear transport in host cells to evade immune defense. Moreover, certain transport factors negatively regulate nuclear protein transport in cells. Understanding the regulatory mechanisms of nuclear–cytoplasmic trafficking not only provides important information about cellular processes, but also is of use for developing specific inhibitors for transport pathways. PMID:22672474

  3. Active transport of vesicles in neurons is modulated by mechanical tension

    NASA Astrophysics Data System (ADS)

    Ahmed, Wylie W.; Saif, Taher A.

    2014-03-01

    Effective intracellular transport of proteins and organelles is critical in cells, and is especially important for ensuring proper neuron functionality. In neurons, most proteins are synthesized in the cell body and must be transported through thin structures over long distances where normal diffusion is insufficient. Neurons transport subcellular cargo along axons and neurites through a stochastic interplay of active and passive transport. Mechanical tension is critical in maintaining proper function in neurons, but its role in transport is not well understood. To this end, we investigate the active and passive transport of vesicles in Aplysia neurons while changing neurite tension via applied strain, and quantify the resulting dynamics. We found that tension in neurons modulates active transport of vesicles by increasing the probability of active motion, effective diffusivity, and induces a retrograde bias. We show that mechanical tension modulates active transport processes in neurons and that external forces can couple to internal (subcellular) forces and change the overall transport dynamics.

  4. Bursts of Active Transport in Living Cells

    NASA Astrophysics Data System (ADS)

    Wang, Bo; Kuo, James; Granick, Steve

    2013-11-01

    We show, using a large new data set, that the temporally resolved speed of active cargo transport in living cells follows a scaling law over several decades of time and length. The statistical regularities display a time-averaged shape that we interpret to reflect stress buildup, followed by rapid release. The scaling power law agrees quantitatively with those reported in inanimate systems (jammed colloids and granular media, and magnetic Barkhausen noise), suggesting a common origin in pushing through a crowded environment in a weak force regime. The implied regulation of the speed of active cellular transport due to environmental obstruction results in bursts of speed and acceleration. These findings extend the classical notion of molecular crowding.

  5. Bursts of active transport in living cells.

    PubMed

    Wang, Bo; Kuo, James; Granick, Steve

    2013-11-15

    We show, using a large new data set, that the temporally resolved speed of active cargo transport in living cells follows a scaling law over several decades of time and length. The statistical regularities display a time-averaged shape that we interpret to reflect stress buildup, followed by rapid release. The scaling power law agrees quantitatively with those reported in inanimate systems (jammed colloids and granular media, and magnetic Barkhausen noise), suggesting a common origin in pushing through a crowded environment in a weak force regime. The implied regulation of the speed of active cellular transport due to environmental obstruction results in bursts of speed and acceleration. These findings extend the classical notion of molecular crowding.

  6. Active and passive calcium transport systems in plant cells

    SciTech Connect

    Sze, H.

    1990-01-01

    The ability to change cytoplasmic Ca{sup 2+} levels ((Ca{sup 2+})) by cells has made this cation a key regulator of many biological processes. Cytoplasmic (Ca{sup 2+}) is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic (Ca{sup 2+}) and active Ca{sup 2+} transport systems that lower cytosolic (Ca{sup 2+}). The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells. 10 figs., 2 tabs.

  7. Active and passive calcium transport systems in plant cells

    SciTech Connect

    Sze, H.

    1991-01-01

    The ability to change cytoplasmic Ca{sup 2+} levels ((Ca{sup 2+})) by cells has made this cation a key regulator of many biological processes. Cytoplasmic (Ca{sup 2+}) is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic (Ca{sup 2+}) and active Ca{sup 2+} transport systems that lower cytosolic (Ca{sup 2+}). The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells.

  8. The transmembrane transporter domain of glutamate transporters is a process tip localizer

    PubMed Central

    Hayashi, Mariko Kato; Yasui, Masato

    2015-01-01

    Glutamate transporters in the central nervous system remove glutamate released from neurons to terminate the signal. These transporters localize to astrocyte process tips approaching neuronal synapses. The mechanisms underlying the localization of glutamate transporters to these processes, however, are not known. In this study, we demonstrate that the trimeric transmembrane transporter domain fragment of glutamate transporters, lacking both N- and C-terminal cytoplasmic regions, localized to filopodia tips. This is a common property of trimeric transporters including a neutral amino acid transporter ASCT1. Astrocyte specific proteins are not required for the filopodia tip localization. An extracellular loop at the centre of the 4th transmembrane helices, unique for metazoans, is required for the localization. Moreover, a C186S mutation at the 4th transmembrane region of EAAT1, found in episodic ataxia patients, significantly decreased its process tip localization. The transmembrane transporter domain fragments of glutamate transporters also localized to astrocyte process tips in cultured hippocampal slice. These results indicate that the transmembrane transporter domain of glutamate transporters have an additional function as a sorting signal to process tips. PMID:25761899

  9. Advocacy for active transport: advocate and city council perspectives

    PubMed Central

    2010-01-01

    Background Effective advocacy is an important part of efforts to increase population participation in physical activity. Research about effective health advocacy is scarce, however, the health sector can learn from the experiences and knowledge of community advocates and those who are on the receiving end of this advocacy. The aim of this study is to explore advocacy for active transport from the perspectives of community advocates and representatives from City councils. Methods Cycling and walking advocates were identified from the local contact list of Cycling Advocates Network and Living Streets Aotearoa. Semi-structured telephone interviews were conducted with cycle and walking advocates from throughout New Zealand. Advocates also nominated a suitable council officer at their local City council to be interviewed. Interviews were recorded and transcribed and categories of responses for each of the questions created. Results Several processes were used by advocates to engage with council staff, including formal council submissions, meetings, stakeholder forums and partnership in running community events promoting active transport. Several other agencies were identified as being influential for active transport, some as potential coalition partners and others as potential adversaries. Barriers to improving conditions for active transport included a lack of funding, a lack of will-power among either council staff or councillors, limited council staff capacity (time or training) and a culture of providing infrastructure for motor vehicles instead of people. Several suggestions were made about how the health sector could contribute to advocacy efforts, including encouraging political commitment, engaging the media, communicating the potential health benefits of active transport to the general public and being role models in terms of personal travel mode choice and having workplaces that support participation in active transport. Conclusions There is potential for the

  10. Quantification of chemical transport processes from soil to surface runoff

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Although there is a conceptual understanding on processes governing chemical transport from soil to surface runoff, there are little literature and research results actually quantifying these individual processes. We developed a laboratory flow cell and experimental procedures to quantify chemical ...

  11. Large-Scale Stratospheric Transport Processes

    NASA Technical Reports Server (NTRS)

    Plumb, R. Alan

    2001-01-01

    The paper discusses the following: 1. The Brewer-Dobson circulation: tropical upwelling. 2. Mixing into polar vortices. 3. The latitudinal structure of "age" in the stratosphere. 4. The subtropical "tracer edges". 5. Transport in the lower troposphere. 6. Tracer modeling during SOLVE. 7. 3D modeling of "mean age". 8. Models and measurements II.

  12. Organic Semiconductors: A Molecular Picture of the Charge-Transport and Energy-Transport Processes.

    NASA Astrophysics Data System (ADS)

    Brédas, Jean-Luc

    2007-03-01

    Conjugated organic oligomer and polymer materials are being increasingly considered for their incorporation as the active semiconductor elements in devices such as photo-voltaic cells, light-emitting diodes, or field-effects transistors. In the operation of these devices, electron-transfer and energy-transfer processes play a key role, for instance in the form of charge transport (in the bulk or across interfaces), energy transport, charge separation, or charge recombination [1]. Here, we provide a theoretical description of electron-transfer phenomena based on electron-transfer theory, which allows us to provide a molecular, chemically-oriented understanding. In this presentation, we focus on the parameters that impact the mobility of charge carriers [2], that is the electronic coupling within chains and between adjacent chains and the reorganization energy of the chains upon ionization. Materials under study include conjugated oligomers such as oligoacenes, oligothiophene-acenes, oligothiophenes, and oligothienacenes. [1] J.L. Br'edas, D. Beljonne, V. Coropceanu, and J. Cornil, ``Charge-Transfer and Energy-Transfer Processes in pi-Conjugated Oligomers and Polymers'', Chemical Reviews, 104, 4971-5004 (2004). [2] V. Coropceanu, J. Cornil, D.A. da Silva Filho, Y. Olivier, R. Silbey, and J.L. Br'edas, ``Charge Transport in Organic Semiconductors'', Chemical Reviews, 107, xxx (2007).

  13. Active learning in transportation engineering education

    NASA Astrophysics Data System (ADS)

    Weir, Jennifer Anne

    The objectives of this research were (1) to develop experimental active-based-learning curricula for undergraduate courses in transportation engineering and (2) to assess the effectiveness of an active-learning-based traffic engineering curriculum through an educational experiment. The researcher developed a new highway design course as a pilot study to test selected active-learning techniques before employing them in the traffic engineering curriculum. Active-learning techniques, including multiple-choice questions, short problems completed by individual students or small groups, and group discussions, were used as active interludes within lectures. The researcher also collected and analyzed student performance and attitude data from control and experimental classes to evaluate the relative effectiveness of the traditional lecture (control) approach and the active-learning (experimental) approach. The results indicate that the active-learning approach adopted for the experimental class did have a positive impact on student performance as measured by exam scores. The students in the experimental class also indicated slightly more positive attitudes at the end of the course than the control class, although the difference was not significant. The author recommends that active interludes similar to those in the experimental curricula be used in other courses in civil engineering.

  14. Activation of ion transport systems during cell volume regulation

    SciTech Connect

    Eveloff, J.L.; Warnock, D.G.

    1987-01-01

    This review discusses the activation of transport pathways during volume regulation, including their characteristics, the possible biochemical pathways that may mediate the activation of transport pathways, and the relations between volume regulation and transepithelial transport in renal cells. Many cells regulate their volume when exposed to an anisotonic medium. The changes in cell volume are caused by activation of ion transport pathways, plus the accompanying osmotically driven water movement such that cell volume returns toward normal levels. The swelling of hypertonically shrunken cells is termed regulatory volume increase (RVI) and involves an influx of NaCl into the cell via either activation of Na-Cl, Na-K-2Cl cotransport systems, or Na/sup +/-H/sup +/ and Cl/sup -/-HCO/sub 3//sup -/ exchangers. The reshrinking of hypotonically swollen cells is termed regulatory volume decrease (RVD) and involves an efflux of KCl and water from the cell by activation of either separate K/sup +/ and Cl/sup -/ conductances, a K-Cl cotransport system, or parallel K/sup +/-H/sup +/ and Cl/sup -/-HCO/sub 3//sup -/ exchangers. The biochemical mechanisms involved in the activation of transport systems are largely unknown, however, the phosphoinositide pathway may be implicated in RVI; phorbol esters, cGMP, and Ca/sup 2 +/ affect the process of volume regulation. Renal tubular cells, as well as the blood cells that transverse the medulla, are subjected to increasing osmotic gradients from the corticomedullary junction to the papillary tip, as well as changing interstitial and tubule fluid osmolarity, depending on the diuretic state of the animal. Medullary cells from the loop of Henle and the papilla can volume regulate by activating Na-K-2Cl cotransport or Na/sup +/-H/sup +/ and Cl/sup -/-HCO/sub 3//sup -/ exchange systems.

  15. Single-molecule detection with active transport

    NASA Astrophysics Data System (ADS)

    Ball, David Allan

    A glass capillary is used near the focal region of a custom-built confocal microscope to investigate the use of active transport for single-molecule detection in solution, with both one and two-photon laser excitation. The capillary tip has a diameter of several microns and is carefully aligned nearby to the sub-micron laser beam waist, collinear to the optical axis, so that a negative pressure-difference causes molecules to be drawn into the capillary, along the laser beam axis. The flow of solution, which is characterized by fluorescence correlation spectroscopy (FCS), can increase the single-molecule detection rate for slowly diffusing proteins by over a factor of 100, while the mean rate of photons during each burst is similar to that for random diffusional transport. Also, the flow is along the longest axis of the ellipsoidally-shaped confocal volume, which results in more collected photons per molecule than that for transverse flow at the same speed. When transport is dominated by flow, FCS can no longer distinguish molecules with differing translational diffusion, and hence a fluorescence fluctuation spectroscopy method based on differences in fluorescence brightness is investigated as a means for assaying different solution components, for applications in pharmaceutical drug discovery. Multi-channel fluctuation spectroscopy techniques can also be used for assays with the flow system and hence this dissertation also reports the characterization of a prototype 4-channel single-photon detector with a two-wavelength polarization-resolved optical set-up.

  16. Strategies for Processing Semen from Subfertile Stallions for Cooled Transport.

    PubMed

    Varner, Dickson D

    2016-12-01

    Subfertility can be a confusing term because some semen of good quality can have reduced fertility following cooled transport if the semen is processed in an improper manner. General procedures aimed at processing stallion semen for cooled transport are well described. An array of factors could exist in reduced fertility of cool-transported semen. This article focuses on centrifugation techniques that can be used to maximize sperm quality of stallions whose semen is intended for cooled transport. Clinical cases are also provided for practical application of techniques.

  17. Transport in active systems crowded by obstacles

    NASA Astrophysics Data System (ADS)

    Huang, Mu-Jie; Schofield, Jeremy; Kapral, Raymond

    2017-02-01

    The reactive and diffusive dynamics of a single chemically powered Janus motor in a crowded medium of moving but passive obstacles is investigated using molecular simulation. It is found that the reaction rate of the catalytic motor reaction decreases in a crowded medium as the volume fraction of obstacles increases as a result of a reduction in the Smoluchowski diffusion-controlled reaction rate coefficient that contributes to the overall reaction rate. A continuum model is constructed and analyzed to interpret the dependence of the steady-state reaction rate observed in simulations on the volume fraction of obstacles in the system. The steady-state concentration fields of reactant and product are shown to be sensitive to the local structure of obstacles around the Janus motor. It is demonstrated that the active motor exhibits enhanced diffusive motion at long times with a diffusion constant that decreases as the volume fraction of crowding species increases. In addition, the dynamical properties of a passive tracer particle in a system containing many active Janus motors is studied to investigate how an active environment influences the transport of non-active species. The diffusivity of a passive tracer particle in an active medium is found to be enhanced in systems with forward-moving Janus motors due to the cooperative dynamics of these motors.

  18. Extraterrestrial materials processing and related transport phenomena

    NASA Technical Reports Server (NTRS)

    Ramohalli, K. N. R.; Sridhar, K. R.

    1991-01-01

    Several concepts for significant cost reductions in extraterrestrial resource utilization are described. After an introduction of the desirability of in situ resource utilization, several candidate chemical processes are mentioned. It is brought out that many of the key processes require fluid dynamics and heat transfer processes under reduced- and microgravity. These aspects are discussed within the broad framework of a two-phase thermal control systems. Another important aspect of space processing is that reliability and self-repairability are mandatory; automation aspects are discussed. In addition to these general considerations, the paper includes several specific processes that vary from solid electrolytic production of oxygen from carbon dioxide, to plasma-augmented reactions for reducing ilmenite on the moon.

  19. Divide and conquer: processive transport enables multidrug transporters to tackle challenging drugs

    PubMed Central

    Fluman, Nir; Bibi, Eitan

    2014-01-01

    Multidrug transporters are membrane proteins that catalyze efflux of antibiotics and other toxic compounds from cells, thereby conferring drug resistance on various organisms. Unlike most solute transporters that transport a single type of compound or similar analogues, multidrug transporters are extremely promiscuous. They transport a broad spectrum of dissimilar drugs and represent a serious obstacle to antimicrobial or anticancer chemotherapy. Many challenging aspects of multidrug transporters, which are unique, have been studied in detail, including their ability to interact with chemically unrelated drugs, and how they utilize energy to drive efflux of compounds that are not only structurally but electrically different. A new and surprising dimension of the promiscuous nature of multidrug transporters has been described recently: they can move long molecules through the membrane in a processive manner. PMID:28357213

  20. Processes of Salt Transport in Disturbed Streams

    NASA Astrophysics Data System (ADS)

    Chitrakar, S.; Miller, S. N.; Caffrey, P. A.; Stern, J.

    2013-12-01

    The extraction of coal bed methane natural gas involves removal of large amount of ground/Coal Bed Methane (CBM) water which is commonly discharged to surface-water drainages or constructed reservoirs. The extraction of large volume of water and its disposal on soil surface not only lowers the water table but also potentially accelerate soil erosions, contaminate surface water resources, and alter the natural flows. Due to the difference in quality and quantity between the surface discharge and disposed CBM water, this management strategy potentially poses threats to quality of surface water and soil. CBM discharge water typically contains high concentrations of sodium and low concentrations of calcium and magnesium, resulting in high sodium adsorption ratio (SAR). Similarly, it also contains high concentration of other ions which could results in increasing salt concentrations. Our study area is in the Atlantic Rim development area of the Muddy Creek, SE of Wyoming, a tributary to Colorado River, where significant development of CBM wells is ongoing. Since Muddy Creek is part of the Upper Colorado River, the greatest concern is its potential to contribute to surface water quality (primarily salinity) impairment downstream. However, very few studies have made efforts to assess the water quality in this particular region. The alteration of stream water quality in this region is still not fully understood if it due to CBM water discharge or via soil/water interactions, erosion, and sediment transport. Efforts are being made to identify crucial water quality parameters such as SAR and EC along with the quantification of solute/salt loadings at both CBM discharge fed streams and natural streams at different seasons to distinguish effect of CBM discharge on water quality. We have been continuously monitoring water quality on monthly basis and discharge measurement on daily basis at sampling sites that are placed to discriminate CBM fed streams and natural streams. The

  1. Nucleocytoplasmic transport of ribosomes in a eukaryotic system: Is there a facilitated transport process

    SciTech Connect

    Khanna-Gupta, A.; Ware, V.C. )

    1989-03-01

    The authors have examined the kinetics of the process by which ribosomes are exported from the nucleus to the cytoplasm using Xenopus laevis oocytes microinjected into the germinal vesicle with radiolabeled ribosomes or ribosomal subunits from X. laevis, Tetrahymena thermophila, or Escherichia coli. Microinjected eukaryotic mature ribosomes are redistributed into the oocyte cytoplasm by an apparent carrier-mediated transport process that exhibits saturation kinetics as increasing amounts of ribosomes are injected. T. thermophila ribosomes are competent to traverse the Xenopus nuclear envelope, suggesting that the basic mechanism underlying ribosome transport is evolutionarily conserved. Microinjected E. coli ribosomes are not transported in this system, indicating that prokaryotic ribosomes lack the signals required for transport. Surprisingly, coinjected small (40S) and large (60S) subunits from T. thermophila are transported significantly faster than individual subunits. These observations support a facilitated transport model for the translocation of ribosomal subunits as separate units across the nuclear envelope whereby the transport rate of 60S or 40S subunits is enhanced by the presence of the partner subunit. Although the basic features of the transport mechanism have been preserved through evolution, other aspects of the process may be mediated through species-specific interactions. They hypothesize that a species-specific nuclear 40S-60S subunit association may expedite the transport of individual subunits across the nuclear envelope.

  2. A general method for determining secondary active transporter substrate stoichiometry.

    PubMed

    Fitzgerald, Gabriel A; Mulligan, Christopher; Mindell, Joseph A

    2017-01-25

    The number of ions required to drive substrate transport through a secondary active transporter determines the protein's ability to create a substrate gradient, a feature essential to its physiological function, and places fundamental constraints on the transporter's mechanism. Stoichiometry is known for a wide array of mammalian transporters, but, due to a lack of readily available tools, not for most of the prokaryotic transporters for which high-resolution structures are available. Here, we describe a general method for using radiolabeled substrate flux assays to determine coupling stoichiometries of electrogenic secondary active transporters reconstituted in proteoliposomes by measuring transporter equilibrium potentials. We demonstrate the utility of this method by determining the coupling stoichiometry of VcINDY, a bacterial Na(+)-coupled succinate transporter, and further validate it by confirming the coupling stoichiometry of vSGLT, a bacterial sugar transporter. This robust thermodynamic method should be especially useful in probing the mechanisms of transporters with available structures.

  3. Transport processes in biological systems: Tumoral cells and human brain

    NASA Astrophysics Data System (ADS)

    Lucia, Umberto

    2014-01-01

    The entropy generation approach has been developed for the analysis of complex systems, with particular regards to biological systems, in order to evaluate their stationary states. The entropy generation is related to the transport processes related to exergy flows. Moreover, cancer can be described as an open complex dynamic and self-organizing system. Consequently, it is used as an example useful to evaluate the different thermo-chemical quantities of the transport processes in normal and in tumoral cells systems.

  4. Transport induced by mean-eddy interaction: II. Analysis of transport processes

    NASA Astrophysics Data System (ADS)

    Ide, Kayo; Wiggins, Stephen

    2015-03-01

    We present a framework for the analysis of transport processes resulting from the mean-eddy interaction in a flow. The framework is based on the Transport Induced by the Mean-Eddy Interaction (TIME) method presented in a companion paper (Ide and Wiggins, 2014) [1]. The TIME method estimates the (Lagrangian) transport across stationary (Eulerian) boundaries defined by chosen streamlines of the mean flow. Our framework proceeds after first carrying out a sequence of preparatory steps that link the flow dynamics to the transport processes. This includes the construction of the so-called "instantaneous flux" as the Hovmöller diagram. Transport processes are studied by linking the signals of the instantaneous flux field to the dynamical variability of the flow. This linkage also reveals how the variability of the flow contributes to the transport. The spatio-temporal analysis of the flux diagram can be used to assess the efficiency of the variability in transport processes. We apply the method to the double-gyre ocean circulation model in the situation where the Rossby-wave mode dominates the dynamic variability. The spatio-temporal analysis shows that the inter-gyre transport is controlled by the circulating eddy vortices in the fast eastward jet region, whereas the basin-scale Rossby waves have very little impact.

  5. Understanding the transport processes in polymer electrolyte membrane fuel cells

    NASA Astrophysics Data System (ADS)

    Cheah, May Jean

    Polymer electrolyte membrane (PEM) fuel cells are energy conversion devices suitable for automotive, stationary and portable applications. An engineering challenge that is hindering the widespread use of PEM fuel cells is the water management issue, where either a lack of water (resulting in membrane dehydration) or an excess accumulation of liquid water (resulting in fuel cell flooding) critically reduces the PEM fuel cell performance. The water management issue is addressed by this dissertation through the study of three transport processes occurring in PEM fuel cells. Water transport within the membrane is a combination of water diffusion down the water activity gradient and the dragging of water molecules by protons when there is a proton current, in a phenomenon termed electro-osmotic drag, EOD. The impact of water diffusion and EOD on the water flux across the membrane is reduced due to water transport resistance at the vapor/membrane interface. The redistribution of water inside the membrane by EOD causes an overall increase in the membrane resistance that regulates the current and thus EOD, thereby preventing membrane dehydration. Liquid water transport in the PEM fuel cell flow channel was examined at different gas flow regimes. At low gas Reynolds numbers, drops transitioned into slugs that are subsequently pushed out of the flow channel by the gas flow. The slug volume is dependent on the geometric shape, the surface wettability and the orientation (with respect to gravity) of the flow channel. The differential pressure required for slug motion primarily depends on the interfacial forces acting along the contact lines at the front and the back of the slug. At high gas Reynolds number, water is removed as a film or as drops depending on the flow channel surface wettability. The shape of growing drops at low and high Reynolds number can be described by a simple interfacial energy minimization model. Under flooding conditions, the fuel cell local current

  6. Berberine acutely activates the glucose transport activity of GLUT1.

    PubMed

    Cok, Alexandra; Plaisier, Christina; Salie, Matthew J; Oram, Daniel S; Chenge, Jude; Louters, Larry L

    2011-07-01

    Berberine, which has a long history of use in Chinese medicine, has recently been shown to have efficacy in the treatment of diabetes. While the hypoglycemic effect of berberine has been clearly documented in animal and cell line models, such as 3T3-L1 adipocytes and L6 myotube cells, the mechanism of action appears complex with data implicating activation of the insulin signaling pathway as well as activation of the exercise or AMP kinase-mediated pathway. There have been no reports of the acute affects of berberine on the transport activity of the insulin-insensitive glucose transporter, GLUT1. Therefore, we examined the acute effects of berberine on glucose uptake in L929 fibroblast cells, a cell line that express only GLUT1. Berberine- activated glucose uptake reaching maximum stimulation of five-fold at >40 μM. Significant activation (P < 0.05) was measured within 5 min reaching a maximum by 30 min. The berberine effect was not additive to the maximal stimulation by other known stimulants, azide, methylene blue or glucose deprivation, suggesting shared steps between berberine and these stimulants. Berberine significantly reduced the K(m) of glucose uptake from 6.7 ± 1.9 mM to 0.55 ± 0.08 mM, but had no effect on the V(max) of uptake. Compound C, an inhibitor of AMP kinase, did not affect berberine-stimulated glucose uptake, but inhibitors of downstream kinases partially blocked berberine stimulation. SB203580 (inhibitor of p38 MAP kinase) did not affect submaximal berberine activation, but did lower maximal berberine stimulation by 26%, while PD98059 (inhibitor of ERK kinase) completely blocked submaximal berberine activation and decreased the maximal stimulation by 55%. It appears from this study that a portion of the hypoglycemic effects of berberine can be attributed to its acute activation of the transport activity of GLUT1.

  7. Stochastic simulations of cargo transport by processive molecular motors

    NASA Astrophysics Data System (ADS)

    Korn, Christian B.; Klumpp, Stefan; Lipowsky, Reinhard; Schwarz, Ulrich S.

    2009-12-01

    We use stochastic computer simulations to study the transport of a spherical cargo particle along a microtubule-like track on a planar substrate by several kinesin-like processive motors. Our newly developed adhesive motor dynamics algorithm combines the numerical integration of a Langevin equation for the motion of a sphere with kinetic rules for the molecular motors. The Langevin part includes diffusive motion, the action of the pulling motors, and hydrodynamic interactions between sphere and wall. The kinetic rules for the motors include binding to and unbinding from the filament as well as active motor steps. We find that the simulated mean transport length increases exponentially with the number of bound motors, in good agreement with earlier results. The number of motors in binding range to the motor track fluctuates in time with a Poissonian distribution, both for springs and cables being used as models for the linker mechanics. Cooperativity in the sense of equal load sharing only occurs for high values for viscosity and attachment time.

  8. Stochastic simulations of cargo transport by processive molecular motors.

    PubMed

    Korn, Christian B; Klumpp, Stefan; Lipowsky, Reinhard; Schwarz, Ulrich S

    2009-12-28

    We use stochastic computer simulations to study the transport of a spherical cargo particle along a microtubule-like track on a planar substrate by several kinesin-like processive motors. Our newly developed adhesive motor dynamics algorithm combines the numerical integration of a Langevin equation for the motion of a sphere with kinetic rules for the molecular motors. The Langevin part includes diffusive motion, the action of the pulling motors, and hydrodynamic interactions between sphere and wall. The kinetic rules for the motors include binding to and unbinding from the filament as well as active motor steps. We find that the simulated mean transport length increases exponentially with the number of bound motors, in good agreement with earlier results. The number of motors in binding range to the motor track fluctuates in time with a Poissonian distribution, both for springs and cables being used as models for the linker mechanics. Cooperativity in the sense of equal load sharing only occurs for high values for viscosity and attachment time.

  9. Thermodynamically coupled mass transport processes in a saturated clay

    SciTech Connect

    Carnahan, C.L.

    1984-11-01

    Gradients of temperature, pressure, and fluid composition in saturated clays give rise to coupled transport processes (thermal and chemical osmosis, thermal diffusion, ultrafiltration) in addition to the direct processes (advection and diffusion). One-dimensional transport of water and a solute in a saturated clay subjected to mild gradients of temperature and pressure was simulated numerically. When full coupling was accounted for, volume flux (specific discharge) was controlled by thermal osmosis and chemical osmosis. The two coupled fluxes were oppositely directed, producing a point of stagnation within the clay column. Solute flows were dominated by diffusion, chemical osmosis, and thermal osmosis. Chemical osmosis produced a significant flux of solute directed against the gradient of solute concentration; this effect reduced solute concentrations relative to the case without coupling. Predictions of mass transport in clays at nuclear waste repositories could be significantly in error if coupled transport processes are not accounted for. 14 references, 8 figures, 1 table.

  10. Integration of a 'proton antenna' facilitates transport activity of the monocarboxylate transporter MCT4.

    PubMed

    Noor, Sina Ibne; Pouyssegur, Jacques; Deitmer, Joachim W; Becker, Holger M

    2017-01-01

    Monocarboxylate transporters (MCTs) mediate the proton-coupled transport of high-energy metabolites like lactate and pyruvate and are expressed in nearly every mammalian tissue. We have shown previously that transport activity of MCT4 is enhanced by carbonic anhydrase II (CAII), which has been suggested to function as a 'proton antenna' for the transporter. In the present study, we tested whether creation of an endogenous proton antenna by introduction of a cluster of histidine residues into the C-terminal tail of MCT4 (MCT4-6xHis) could facilitate MCT4 transport activity when heterologously expressed in Xenopus oocytes. Our results show that integration of six histidines into the C-terminal tail does indeed increase transport activity of MCT4 to the same extent as did coexpression of MCT4-WT with CAII. Transport activity of MCT4-6xHis could be further enhanced by coexpression with extracellular CAIV, but not with intracellular CAII. Injection of an antibody against the histidine cluster into MCT4-expressing oocytes decreased transport activity of MCT4-6xHis, while leaving activity of MCT4-WT unaltered. Taken together, these findings suggest that transport activity of the proton-coupled monocarboxylate transporter MCT4 can be facilitated by integration of an endogenous proton antenna into the transporter's C-terminal tail.

  11. Atomic physics processes in radial transport calculations

    SciTech Connect

    Hogan, J.T.

    1983-02-01

    These lectures were intended as preparation for detailed discussions of the role of atomic and molecular physics in confinement research at the 1982 NATO Advanced Study Institute. They begin with a description of the major approaches to magnetic confinement: tandem (ambipolar) mirrors with their associated auxiliary barriers, tokamaks, and stellarators. The leading alternatives, the ELMO Bumpy Torus and the reversed field pinch, are also treated. The evolution equations for particle, energy, and (where relevant) field diffusion are presented and discussed. This is the context for atomic and molecular processes relevant to confinement.

  12. The maltose ABC transporter: action of membrane lipids on the transporter stability, coupling and ATPase activity.

    PubMed

    Bao, Huan; Dalal, Kush; Wang, Victor; Rouiller, Isabelle; Duong, Franck

    2013-08-01

    The coupling between ATP hydrolysis and substrate transport remains a key question in the understanding of ABC-mediated transport. We show using the MalFGK2 complex reconstituted into nanodiscs, that membrane lipids participate directly to the coupling reaction by stabilizing the transporter in a low energy conformation. When surrounded by short acyl chain phospholipids, the transporter is unstable and hydrolyzes large amounts of ATP without inducing maltose. The presence of long acyl chain phospholipids stabilizes the conformational dynamics of the transporter, reduces its ATPase activity and restores dependence on maltose. Membrane lipids therefore play an essential allosteric function, they restrict the transporter ATPase activity to increase coupling to the substrate. In support to the notion, we show that increasing the conformational dynamics of MalFGK2 with mutations in MalF increases the transporter ATPase activity but decreases the maltose transport efficiency.

  13. Active sodium transport and the electrophysiology of rabbit colon.

    PubMed

    Schultz, S G; Frizzell, R A; Nellans, H N

    1977-05-12

    The electrophysiologic properties of rabbit colonic epithelial cells were investigated employing microelectrode techniques. Under open-circuit conditions, the transepithelial electrical potential difference (PD) averaged 20 mV, serosa positive, and the intracellular electrical potential (psimc) averaged -32 mV, cell interior negative with respect to the mucosal solution; under short-circuit conditions, psimc averaged -46 mV. The addition of amiloride to the mucosal solution abolishes the transepithelial PD and active Na transport, and psimc is hyperpolarized to an average value of -53 mV. These results indicate that Na entry into the mucosal cell is a conductive process which, normally, depolarized psimc. The data obtained were interpreted using a double-membrane equivalent electrical circuit model of the "active Na transport pathway" involving two voltage-independent electromotive forces (emf's) and two voltage-independent resistances arrayed in series. Our observations are consistent with the notions that: (a) The emf's and resistances across the mucosal and baso-lateral membranes are determined predominantly by the emf (64 mV) and resistance of the Na entry process and the emf (53 mV) and resistance of the process responsible for active Na extrusion across the baso-lateral membranes: that is, the electrophysiological properties of the cell appear to be determined solely by the properties and processes responsible for transcellular active Na transport. The emf of the Na entry process is consistent with the notion that the Na activity in the intracellular transport pool is approximately one-tenth that in the mucosal solution or about 14 mM. (b) In the presence of amiloride, the transcellular conductance is essentially abolished and the total tissue conductance is the result of ionic diffusion through paracellular pathways. (c) The negative intracellular potential (with respect to the mucosal solution) is due primarily to the presence of a low resistance

  14. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... performed as part of the exempt transportation will be considered a step in the exempt transportation (Woods... site of the woods operations for transportation to the mill, processing plant, or railroad is not...

  15. A Simple Laboratory Exercise Illustrating Active Transport in Yeast Cells.

    ERIC Educational Resources Information Center

    Stambuk, Boris U.

    2000-01-01

    Describes a simple laboratory activity illustrating the chemiosmotic principles of active transport in yeast cells. Demonstrates the energy coupling mechanism of active a-glucoside uptake by Saccaromyces cerevisiae cells with a colorimetric transport assay using very simple equipment. (Contains 22 references.) (Author/YDS)

  16. Quantum Transport in Solids: Two-Electron Processes.

    DTIC Science & Technology

    1995-07-01

    The central objective of this research program has been to study theoretically the underlying principles of quantum transport in solids. The area of...research investigated has emphasized the understanding of two electron processes in quantum transport . The problems have been treated analytically to...the extent possible through the use of dynamical localized Wannier functions. These results have been and are being incorporated in a full quantum

  17. Quantum Transport in Solids: Two-Electron Processes.

    DTIC Science & Technology

    1995-06-01

    The central objective of this research program has been to study theoretically the underlying principles of quantum transport in solids. The area of...research investigated has emphasized the understanding of two electron processes in quantum transport . The problems have been treated analytically to...the extent possible through the use of dynamical localized Wannier functions. These results have been and are being incorporated in a full quantum

  18. Role of glutathione transport processes in kidney function

    SciTech Connect

    Lash, Lawrence H. . E-mail: l.h.lash@wayne.edu

    2005-05-01

    The kidneys are highly dependent on an adequate supply of glutathione (GSH) to maintain normal function. This is due, in part, to high rates of aerobic metabolism, particularly in the proximal tubules. Additionally, the kidneys are potentially exposed to high concentrations of oxidants and reactive electrophiles. Renal cellular concentrations of GSH are maintained by both intracellular synthesis and transport from outside the cell. Although function of specific carriers has not been definitively demonstrated, it is likely that multiple carriers are responsible for plasma membrane transport of GSH. Data suggest that the organic anion transporters OAT1 and OAT3 and the sodium-dicarboxylate 2 exchanger (SDCT2 or NaDC3) mediate uptake across the basolateral plasma membrane (BLM) and that the organic anion transporting polypeptide OATP1 and at least one of the multidrug resistance proteins mediate efflux across the brush-border plasma membrane (BBM). BLM transport may be used pharmacologically to provide renal proximal tubular cells with exogenous GSH to protect against oxidative stress whereas BBM transport functions physiologically in turnover of cellular GSH. The mitochondrial GSH pool is derived from cytoplasmic GSH by transport into the mitochondrial matrix and is mediated by the dicarboxylate and 2-oxoglutarate exchangers. Maintenance of the mitochondrial GSH pool is critical for cellular and mitochondrial redox homeostasis and is important in determining susceptibility to chemically induced apoptosis. Hence, membrane transport processes are critical to regulation of renal cellular and subcellular GSH pools and are determinants of susceptibility to cytotoxicity induced by oxidants and electrophiles.

  19. Heterogeneous processes affecting metal ion transport in the presence of organic ligands: Reactive transport modeling

    NASA Astrophysics Data System (ADS)

    Kantar, Cetin

    2007-04-01

    The development of models to accurately simulate metal ion transport through saturated systems under variable chemical conditions, e.g., in systems containing organic ligands (L) such as natural organic matter (NOM), has two essential aspects: (1) establishing the ability to simulate metal ion sorption to aquifer solids over a range of metal/ligand ratios; and (2) to incorporate this ability to simulate metal speciation over a range in chemical conditions (e.g., pH, ligand activity) into mass transport models. Modeling approaches to evaluate metal ion sorption and transport in the presence of NOM include: (1) isotherm-based transport models, and (2) multicomponent (MC) transport models. The accuracy of transport models depends on how well the chemical interactions affecting metal ion transport in the presence of organic ligands (e.g., metal/ligand complexation) are described in transport equations. The isotherm-based transport models often fail to accurately describe metal ion transport in the presence of NOM since these models treat NOM as a single solute despite the fact that NOM is a multicomponent mixture of subcomponents with different chemical and polyfunctional behavior. On the other hand, the calculations presented in this study suggest that a multicomponent reactive transport model, in conjunction with a mechanistic modeling approach for the description of metal ion binding by NOM in a manner conducive to the application of surface complexation modeling (SCM), can effectively be used as an important predictive tool in simulating metal ion sorption and transport under variable chemical conditions in the presence of NOM.

  20. Transportation as a "Related Service": Issues that Involve Transition Activities.

    ERIC Educational Resources Information Center

    Missouri Univ., Columbia. Missouri LINC.

    The paper discusses transportation as a related service for students with disabilities expecially as related to school-to-work transition activities. First, the legislative and legal basis for providing transportation services is discussed in the form of answers to frequently asked questions: why provide transportation? what is the basis for…

  1. Air pollution exposure: An activity pattern approach for active transportation

    NASA Astrophysics Data System (ADS)

    Adams, Matthew D.; Yiannakoulias, Nikolaos; Kanaroglou, Pavlos S.

    2016-09-01

    In this paper, we demonstrate the calculation of personal air pollution exposure during trips made by active transportation using activity patterns without personal monitors. We calculate exposure as the inhaled dose of particulate matter 2.5 μg or smaller. Two modes of active transportation are compared, and they include cycling and walking. Ambient conditions are calculated by combining mobile and stationary monitoring data in an artificial neural network space-time model. The model uses a land use regression framework and has a prediction accuracy of R2 = 0.78. Exposure is calculated at 10 m or shorter intervals during the trips using inhalation rates associated with both modes. The trips are children's routes between home and school. The average dose during morning cycling trips was 2.17 μg, during morning walking trips was 3.19 μg, during afternoon cycling trips was 2.19 μg and during afternoon walking trips was 3.23 μg. The cycling trip dose was significantly lower than the walking trip dose. The air pollution exposure during walking or cycling trips could not be strongly predicted by either the school or household ambient conditions, either individually or in combination. Multiple linear regression models regressing both the household and school ambient conditions against the dose were only able to account for, at most, six percent of the variance in the exposure. This paper demonstrates that incorporating activity patterns when calculating exposure can improve the estimate of exposure compared to its calculation from ambient conditions.

  2. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... EMPLOYED § 788.11 “Transporting products to the mill, processing plant, railroad, or other transportation... 29 Labor 3 2011-07-01 2011-07-01 false âTransporting products to the mill, processing plant, railroad, or other transportation terminal.â 788.11 Section 788.11 Labor Regulations Relating to...

  3. Particle Tracking Model and Abstraction of Transport Processes

    SciTech Connect

    B. Robinson

    2004-10-21

    The purpose of this report is to document the abstraction model being used in total system performance assessment (TSPA) model calculations for radionuclide transport in the unsaturated zone (UZ). The UZ transport abstraction model uses the particle-tracking method that is incorporated into the finite element heat and mass model (FEHM) computer code (Zyvoloski et al. 1997 [DIRS 100615]) to simulate radionuclide transport in the UZ. This report outlines the assumptions, design, and testing of a model for calculating radionuclide transport in the UZ at Yucca Mountain. In addition, methods for determining and inputting transport parameters are outlined for use in the TSPA for license application (LA) analyses. Process-level transport model calculations are documented in another report for the UZ (BSC 2004 [DIRS 164500]). Three-dimensional, dual-permeability flow fields generated to characterize UZ flow (documented by BSC 2004 [DIRS 169861]; DTN: LB03023DSSCP9I.001 [DIRS 163044]) are converted to make them compatible with the FEHM code for use in this abstraction model. This report establishes the numerical method and demonstrates the use of the model that is intended to represent UZ transport in the TSPA-LA. Capability of the UZ barrier for retarding the transport is demonstrated in this report, and by the underlying process model (BSC 2004 [DIRS 164500]). The technical scope, content, and management of this report are described in the planning document ''Technical Work Plan for: Unsaturated Zone Transport Model Report Integration'' (BSC 2004 [DIRS 171282]). Deviations from the technical work plan (TWP) are noted within the text of this report, as appropriate. The latest version of this document is being prepared principally to correct parameter values found to be in error due to transcription errors, changes in source data that were not captured in the report, calculation errors, and errors in interpretation of source data.

  4. Active and passive transport of drugs in the human placenta.

    PubMed

    Włoch, Stanisław; Pałasz, Artur; Kamiński, Marcin

    2009-10-01

    The human placenta, characterized by the processes of passive transport and facilitated diffusion, contains numerous active transport proteins, usually located in the microvilli of the syncytiotrophoblast or in the endothelium of the capillaries of the villi. These proteins use either the energy from ATP hydrolysis or other mechanisms resulting, among others, from the formation of the maternofetal ion gradient, which facilitates the transfer of various endogenous substances or xenobiotics across the body membranes. The proteins either trigger the efflux of these substances from the fetal tissues via the placenta into the maternal bloodstream, or conversely they accumulate them in the fetal tissues. Both the placenta and the fetus are equipped with independent systems of enzymes of 1st and 2nd phase of substrate metabolism, such as CYP450, glucuronyltransferase or sulphatase. An active therapy with a wide range of drugs, often at high toxicity levels, either shortly before or during pregnancy, has naturally posed a question concerning the degree of impermeability of the placental barrier and how effectively it can be crossed, including any possible negative embryotoxic or teratogenic consequences. Such hazards seem to be quite real, as many drugs are substrates for ABC transporters. Also the placenta itself, including its structure, is subject to vast transformations during pregnancy which may be observed as the thinning of the barrier separating the maternal blood from the fetal one, from 20-30 microm in the first trimester of gestation down to 2-4 microm in the third trimester of gestation.

  5. Gathering Information from Transport Systems for Processing in Supply Chains

    NASA Astrophysics Data System (ADS)

    Kodym, Oldřich; Unucka, Jakub

    2016-12-01

    Paper deals with complex system for processing information from means of transport acting as parts of train (rail or road). It focuses on automated information gathering using AutoID technology, information transmission via Internet of Things networks and information usage in information systems of logistic firms for support of selected processes on MES and ERP levels. Different kinds of gathered information from whole transport chain are discussed. Compliance with existing standards is mentioned. Security of information in full life cycle is integral part of presented system. Design of fully equipped system based on synthesized functional nodes is presented.

  6. Electro-osmotic transport in wet processing of textiles

    DOEpatents

    Cooper, J.F.

    1998-09-22

    Electro-osmotic (or electrokinetic) transport is used to efficiently force a solution (or water) through the interior of the fibers or yarns of textile materials for wet processing of textiles. The textile material is passed between electrodes that apply an electric field across the fabric. Used alone or in parallel with conventional hydraulic washing (forced convection), electro-osmotic transport greatly reduces the amount of water used in wet processing. The amount of water required to achieve a fixed level of rinsing of tint can be reduced, for example, to 1--5 lbs water per pound of fabric from an industry benchmark of 20 lbs water/lb fabric. 5 figs.

  7. Electro-osmotic transport in wet processing of textiles

    DOEpatents

    Cooper, John F.

    1998-01-01

    Electro-osmotic (or electrokinetic) transport is used to efficiently force a solution (or water) through the interior of the fibers or yarns of textile materials for wet processing of textiles. The textile material is passed between electrodes that apply an electric field across the fabric. Used alone or in parallel with conventional hydraulic washing (forced convection), electro-osmotic transport greatly reduces the amount of water used in wet processing. The amount of water required to achieve a fixed level of rinsing of tint can be reduced, for example, to 1-5 lbs water per pound of fabric from an industry benchmark of 20 lbs water/lb fabric.

  8. Using hydraulic equivalences to discriminate transport processes of volcanic flows

    NASA Astrophysics Data System (ADS)

    Burgisser, Alain; Gardner, James E.

    2006-03-01

    We characterized stratified deposits from the Upper Toluca Pumice at Toluca volcano, Mexico, to distinguish the various modes of transport at play in their genesis. Using the concept of hydraulic equivalence, we determined that deposits resulted from a combination of suspended-load fallout, saltation, and rolling. In particular, some well-sorted coarse stratified beds have a single pumice mode most likely indicative of clasts having traveled through both the transport system and the traction bed. Such beds are likely remnants of the sorting operated within the large-scale transport system. Other coarse beds have pumice and lithic modes suggesting rolling in the traction bed. We propose that boundary layer processes control the sorting of those beds and all finer beds. By helping to discriminate between transport mechanisms, hydraulic equivalences have a general applicability in geophysical flows involving clasts of contrasted densities.

  9. Active transmembrane drug transport in microgravity: a validation study using an ABC transporter model.

    PubMed

    Vaquer, Sergi; Cuyàs, Elisabet; Rabadán, Arnau; González, Albert; Fenollosa, Felip; de la Torre, Rafael

    2014-01-01

    Microgravity has been shown to influence the expression of ABC (ATP-Binding Cassette) transporters in bacteria, fungi and mammals, but also to modify the activity of certain cellular components with structural and functional similarities to ABC transporters. Changes in activity of ABC transporters could lead to important metabolic disorders and undesired pharmacological effects during spaceflights. However, no current means exist to study the functionality of these transporters in microgravity. To this end, a Vesicular Transport Assay (®) (Solvo Biotechnology, Hungary) was adapted to evaluate multi-drug resistance-associated protein 2 (MRP2) trans-membrane estradiol-17-β-glucuronide (E17βG) transport activity, when activated by adenosine-tri-phosphate (ATP) during parabolic flights. Simple diffusion, ATP-independent transport and benzbromarone inhibition were also evaluated. A high accuracy engineering system was designed to perform, monitor and synchronize all procedures. Samples were analysed using a validated high sensitivity drug detection protocol. Experiments were performed in microgravity during parabolic flights, and compared to 1g on ground results using identical equipment and procedures in all cases. Our results revealed that sufficient equipment accuracy and analytical sensitivity were reached to detect transport activity in both gravitational conditions. Additionally, transport activity levels of on ground samples were within commercial transport standards, proving the validity of the methods and equipment used. MRP2 net transport activity was significantly reduced in microgravity, so was signal detected in simple diffusion samples. Ultra-structural changes induced by gravitational stress upon vesicle membranes or transporters could explain the current results, although alternative explanations are possible. Further research is needed to provide a conclusive answer in this regard. Nevertheless, the present validated technology opens new and

  10. Active transmembrane drug transport in microgravity: a validation study using an ABC transporter model

    PubMed Central

    Vaquer, Sergi; Cuyàs, Elisabet; Rabadán, Arnau; González, Albert; Fenollosa, Felip; de la Torre, Rafael

    2014-01-01

    Microgravity has been shown to influence the expression of ABC (ATP-Binding Cassette) transporters in bacteria, fungi and mammals, but also to modify the activity of certain cellular components with structural and functional similarities to ABC transporters. Changes in activity of ABC transporters could lead to important metabolic disorders and undesired pharmacological effects during spaceflights. However, no current means exist to study the functionality of these transporters in microgravity. To this end, a Vesicular Transport Assay ® (Solvo Biotechnology, Hungary) was adapted to evaluate multi-drug resistance-associated protein 2 (MRP2) trans-membrane estradiol-17-β-glucuronide (E17βG) transport activity, when activated by adenosine-tri-phosphate (ATP) during parabolic flights. Simple diffusion, ATP-independent transport and benzbromarone inhibition were also evaluated. A high accuracy engineering system was designed to perform, monitor and synchronize all procedures. Samples were analysed using a validated high sensitivity drug detection protocol. Experiments were performed in microgravity during parabolic flights, and compared to 1g on ground results using identical equipment and procedures in all cases. Our results revealed that sufficient equipment accuracy and analytical sensitivity were reached to detect transport activity in both gravitational conditions. Additionally, transport activity levels of on ground samples were within commercial transport standards, proving the validity of the methods and equipment used. MRP2 net transport activity was significantly reduced in microgravity, so was signal detected in simple diffusion samples. Ultra-structural changes induced by gravitational stress upon vesicle membranes or transporters could explain the current results, although alternative explanations are possible. Further research is needed to provide a conclusive answer in this regard. Nevertheless, the present validated technology opens new and

  11. Active Inference: A Process Theory.

    PubMed

    Friston, Karl; FitzGerald, Thomas; Rigoli, Francesco; Schwartenbeck, Philipp; Pezzulo, Giovanni

    2017-01-01

    This article describes a process theory based on active inference and belief propagation. Starting from the premise that all neuronal processing (and action selection) can be explained by maximizing Bayesian model evidence-or minimizing variational free energy-we ask whether neuronal responses can be described as a gradient descent on variational free energy. Using a standard (Markov decision process) generative model, we derive the neuronal dynamics implicit in this description and reproduce a remarkable range of well-characterized neuronal phenomena. These include repetition suppression, mismatch negativity, violation responses, place-cell activity, phase precession, theta sequences, theta-gamma coupling, evidence accumulation, race-to-bound dynamics, and transfer of dopamine responses. Furthermore, the (approximately Bayes' optimal) behavior prescribed by these dynamics has a degree of face validity, providing a formal explanation for reward seeking, context learning, and epistemic foraging. Technically, the fact that a gradient descent appears to be a valid description of neuronal activity means that variational free energy is a Lyapunov function for neuronal dynamics, which therefore conform to Hamilton's principle of least action.

  12. Transporting Radioactive Waste: An Engineering Activity. Grades 5-12.

    ERIC Educational Resources Information Center

    HAZWRAP, The Hazardous Waste Remedial Actions Program.

    This brochure contains an engineering activity for upper elementary, middle school, and high school students that examines the transportation of radioactive waste. The activity is designed to inform students about the existence of radioactive waste and its transportation to disposal sites. Students experiment with methods to contain the waste and…

  13. Active urea transport independent of H+ and Na+ transport in frog skin epithelium.

    PubMed

    Lacoste, I; Dunel-Erb, S; Harvey, B J; Laurent, P; Ehrenfeld, J

    1991-10-01

    We investigated the relationship between H+ secretion (JH), Na+ absorption (JNa), and urea transport (Ju) in skin of frogs (Rana esculenta) adapted to running tap water, NaCl (100 mM), and KCl (100 mM). In addition, cell morphological changes, particularly in the mitochondria-rich cells (MRC), were followed. NaCl adaptation stimulated an active Ju, reduced JNa and JH, and caused a decrease in the apical surface of MRC. After KCl adaptation, JNa and JH were increased and highly correlated, with a twofold increase in Ju, whereas the numerous MRC developed infoldings on their apical membranes. No correlation was found between JH and Ju. Clamping the skins in a range of +/- 50 mV or changing the external pH from 7.4 to 5.4 (at high cellular buffering power) had no effect on Ju. Depolarization of the basolateral membranes (serosal KCl-Ringer) had no effect on Ju. Ju was reversibly blocked by acidification of the cells by oxygen-free solution and sulfhydryl reagents (Hg2+, p-chloromercuribenzenesulfonic acid, and N-ethylmaleimide). Diethylstilbestrol, a proton transport blocker, had no effect on Ju. Apical addition of amiloride and derivatives (phenamil and ethylisopropyl amiloride) reversibly blocked Ju, whereas ouabain had no effect. We conclude that a cation (Na+ or H+)-dependent process is unlikely to exist in R. esculenta skin. A primary active transport in a two-step process is the simplest hypothesis to account for the energy-dependent Ju that develops in NaCl-adapted frogs.

  14. Features, Events, and Processes in UZ Flow and Transport

    SciTech Connect

    P. Persoff

    2004-11-06

    The evaluation of impacts of potential volcanic eruptions on populations and facilities far in the future may involve detailed volcanological studies that differ from traditional hazards analyses. The proximity of Quaternary volcanoes to a proposed repository for disposal of the USA's high-level radioactive waste at Yucca Mountain, Nevada, has required in-depth study of probability and consequences of basaltic igneous activity. Because of the underground nature of the repository, evaluation of the potential effects of dike intrusion and interaction with the waste packages stored in underground tunnels (dnfts) as well as effects of eruption and ash dispersal have been important. These studies include analyses of dike propagation, dike-drift intersection, flow of magma into dnfts, heat and volcanic gas migration, atmospheric dispersal of tephra, and redistribution of waste-contaminated tephra by surficial processes. Unlike traditional volcanic hazards studies that focus on impacts on housing, transportation, communications, etc. (to name a small subset), the igneous consequences studies at Yucca Mountain have focused on evaluation of igneous impacts on nuclear waste packages and implications for enhanced radioactive dose on a hypothetical future ({le} 10000 yrs) local population. Potential exposure pathways include groundwater (affected by in-situ degradation of waste packages by igneous heat and corrosion) and inhalation, ingestion, and external exposure due to deposition and redistribution of waste-contaminated tephra.

  15. Forest Canopy Processes in a Regional Chemical Transport Model

    NASA Astrophysics Data System (ADS)

    Makar, Paul; Staebler, Ralf; Akingunola, Ayodeji; Zhang, Junhua; McLinden, Chris; Kharol, Shailesh; Moran, Michael; Robichaud, Alain; Zhang, Leiming; Stroud, Craig; Pabla, Balbir; Cheung, Philip

    2016-04-01

    Forest canopies have typically been absent or highly parameterized in regional chemical transport models. Some forest-related processes are often considered - for example, biogenic emissions from the forests are included as a flux lower boundary condition on vertical diffusion, as is deposition to vegetation. However, real forest canopies comprise a much more complicated set of processes, at scales below the "transport model-resolved scale" of vertical levels usually employed in regional transport models. Advective and diffusive transport within the forest canopy typically scale with the height of the canopy, and the former process tends to dominate over the latter. Emissions of biogenic hydrocarbons arise from the foliage, which may be located tens of metres above the surface, while emissions of biogenic nitric oxide from decaying plant matter are located at the surface - in contrast to the surface flux boundary condition usually employed in chemical transport models. Deposition, similarly, is usually parameterized as a flux boundary condition, but may be differentiated between fluxes to vegetation and fluxes to the surface when the canopy scale is considered. The chemical environment also changes within forest canopies: shading, temperature, and relativity humidity changes with height within the canopy may influence chemical reaction rates. These processes have been observed in a host of measurement studies, and have been simulated using site-specific one-dimensional forest canopy models. Their influence on regional scale chemistry has been unknown, until now. In this work, we describe the results of the first attempt to include complex canopy processes within a regional chemical transport model (GEM-MACH). The original model core was subdivided into "canopy" and "non-canopy" subdomains. In the former, three additional near-surface layers based on spatially and seasonally varying satellite-derived canopy height and leaf area index were added to the original model

  16. Heat transport in active harmonic chains

    SciTech Connect

    Zheng, Mei C.; Ellis, Fred M.; Kottos, Tsampikos; Fleischmann, Ragnar; Geisel, Theo; Prosen, Tomaz

    2011-08-15

    We show that a harmonic lattice model with amplifying and attenuating elements, when coupled to two thermal baths, exhibits unique heat transport properties. Some of these novel features include anomalous nonequilibrium steady-state heat currents, negative differential thermal conductance, as well as nonreciprocal heat transport. We find that when these elements are arranged in a PT-symmetric manner, the domain of existence of the nonequilibrium steady state is maximized. We propose an electronic experimental setup based on resistive-inductive-capacitive (RLC) transmission lines, where our predictions can be tested.

  17. Features, Events, and Processes in UZ Flow and Transport

    SciTech Connect

    J.E. Houseworth

    2001-04-10

    Unsaturated zone (UZ) flow and radionuclide transport is a component of the natural barriers that affects potential repository performance. The total system performance assessment (TSPA) model, and underlying process models, of this natural barrier component capture some, but not all, of the associated features, events, and processes (FEPs) as identified in the FEPs Database (Freeze, et al. 2001 [154365]). This analysis and model report (AMR) discusses all FEPs identified as associated with UZ flow and radionuclide transport. The purpose of this analysis is to give a comprehensive summary of all UZ flow and radionuclide transport FEPs and their treatment in, or exclusion from, TSPA models. The scope of this analysis is to provide a summary of the FEPs associated with the UZ flow and radionuclide transport and to provide a reference roadmap to other documentation where detailed discussions of these FEPs, treated explicitly in TSPA models, are offered. Other FEPs may be screened out from treatment in TSPA by direct regulatory exclusion or through arguments concerning low probability and/or low consequence of the FEPs on potential repository performance. Arguments for exclusion of FEPs are presented in this analysis. Exclusion of specific FEPs from the UZ flow and transport models does not necessarily imply that the FEP is excluded from the TSPA. Similarly, in the treatment of included FEPs, only the way in which the FEPs are included in the UZ flow and transport models is discussed in this document. This report has been prepared in accordance with the technical work plan for the unsaturated zone subproduct element (CRWMS M&O 2000 [153447]). The purpose of this report is to document that all FEPs are either included in UZ flow and transport models for TSPA, or can be excluded from UZ flow and transport models for TSPA on the basis of low probability or low consequence. Arguments for exclusion are presented in this analysis. Exclusion of specific FEPs from UZ flow and

  18. Active urea transport by the skin of Bufo viridis: Amiloride- and phloretin-sensitive transport sites

    SciTech Connect

    Rapoport, J.; Abuful, A.; Chaimovitz, C.; Noeh, Z.; Hays, R.M. Albert Einstein College of Medicine, New York, NY )

    1988-09-01

    Urea is actively transported inwardly (J{sub i}) across the skin of the green toad Bufo viridis. J{sub i} is markedly enhanced in toads adapted to hypertonic saline. The authors studied urea transport across the skin of Bufo viridis under a variety of experimental conditions, including treatment with amiloride and phloretin, agents that inhibit urea permeability in the bladder of Bufo marinus. Amiloride (10{sup {minus}4} M) significantly inhibited J{sub i} in both adapted and unadapted animals and was unaffected by removal of sodium from the external medium. Phloretin (10{sup {minus}4} M) significantly inhibited J{sub i} in adapted animals by 23-46%; there was also a reduction in J{sub i} in unadapted toads at 10{sup {minus}4} and 5 {times} 10{sup {minus}4} M phloretin. A dose-response study revealed that the concentration of phloretin causing half-maximal inhibition (K{sub {1/2}}) was 5 {times} 10{sup {minus}4} M for adapted animals. J{sub i} was unaffected by the substitution of sucrose for Ringer solution or by ouabain. They conclude (1) the process of adaptation appears to involve an increase in the number of amiloride- and phloretin-inhibitable urea transport sites in the skin, with a possible increase in the affinity of the sites for phloretin; (2) the adapted skin resembles the Bufo marinus urinary bladder with respect to amiloride and phloretin-inhibitable sites; (3) they confirm earlier observations that J{sub i} is independent of sodium transport.

  19. Transport and biological activities of bile acids.

    PubMed

    Zwicker, Brittnee L; Agellon, Luis B

    2013-07-01

    Bile acids have emerged as important biological molecules that support the solubilization of various lipids and lipid-soluble compounds in the gut, and the regulation of gene expression and cellular function. Bile acids are synthesized from cholesterol in the liver and eventually released into the small intestine. The majority of bile acids are recovered in the distal end of the small intestine and then returned to the liver for reuse. The components of the mechanism responsible for the recycling of bile acids within the enterohepatic circulation have been identified whereas the mechanism for intracellular transport is less understood. Recently, the ileal lipid binding protein (ILBP; human gene symbol FABP6) was shown to be needed for the efficient transport of bile acids from the apical side to the basolateral side of enterocytes in the distal intestine. This review presents an overview of the transport of bile acids between the liver and the gut as well as within hepatocytes and enterocytes. A variety of pathologies is associated with the malfunction of the bile acid transport system.

  20. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  1. Modeling of natural organic matter transport processes in groundwater.

    PubMed Central

    Yeh, T C; Mas-Pla, J; McCarthy, J F; Williams, T M

    1995-01-01

    A forced-gradient tracer test was conducted at the Georgetown site to study the transport of natural organic matter (NOM) in groundwater. In particular, the goal of this experiment was to investigate the interactions between NOM and the aquifer matrix. A detailed three-dimensional characterization of the hydrologic conductivity heterogeneity of the site was obtained using slug tests. The transport of a conservative tracer (chloride) was successfully reproduced using these conductivity data. Despite the good simulation of the flow field, NOM breakthrough curves could not be reproduced using a two-site sorption model with spatially constant parameters. Preliminary results suggest that different mechanisms for the adsorption/desorption processes, as well as their spatial variability, may significantly affect the transport and fate of NOM. PMID:7621798

  2. Nonlinear transport processes in tokamak plasmas. I. The collisional regimes

    NASA Astrophysics Data System (ADS)

    Sonnino, Giorgio; Peeters, Philippe

    2008-06-01

    An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear ("Onsager") transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlüter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for Joint European Torus (JET) plasmas are also reported. It is found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor that may be of the order 102. The nonlinear classical coefficients exceed the neoclassical ones by a factor that may be of order 2. For JET, the discrepancy between experimental and theoretical results for the electron losses is therefore significantly reduced by a factor 102 when the nonlinear contributions are duly taken into account but, there is still a factor of 102 to be explained. This is most likely due to turbulence. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain unaltered. The low-collisional regimes, i.e., the plateau and the banana regimes, are analyzed in the second part of this work.

  3. Study of active cooling for supersonic transports

    NASA Technical Reports Server (NTRS)

    Brewer, G. D.; Morris, R. E.

    1975-01-01

    The potential benefits of using the fuel heat sink of hydrogen fueled supersonic transports for cooling large portions of the aircraft wing and fuselage are examined. The heat transfer would be accomplished by using an intermediate fluid such as an ethylene glycol-water solution. Some of the advantages of the system are: (1) reduced costs by using aluminum in place of titanium, (2) reduced cabin heat loads, and (3) more favorable environmental conditions for the aircraft systems. A liquid hydrogen fueled, Mach 2.7 supersonic transport aircraft design was used for the reference uncooled vehicle. The cooled aircraft designs were analyzed to determine their heat sink capability, the extent and location of feasible cooled surfaces, and the coolant passage size and spacing.

  4. [Model of active peristaltic transport in biosystems].

    PubMed

    Klochkov, B N; Romanov, A S

    2013-01-01

    A nonlinear distributed mathematical model of soft vessel with the nonmonotonous static characteristic is proposed and considered. The model describes space-time dynamics of vessel clearance change. Wave phenomena in vessels of different nature and the possibility of peristaltic fluid pumping are discussed and analyzed. The model is rather common in character and represents a description of the whole class of transport phenomena. Lymphatic vessels are particularly considered.

  5. Process-based modeling of tsunami inundation and sediment transport

    USGS Publications Warehouse

    Apotsos, A.; Gelfenbaum, G.; Jaffe, B.

    2011-01-01

    The infrequent and unpredictable nature of tsunamis precludes the use of field experiments to measure the hydrodynamic and sediment transport processes that occur. Instead, these processes are often approximated from laboratory, numerical, and theoretical studies or inferred from observations of the resultant sediment deposits. Here Delft3D, a three-dimensional numerical model, is used to simulate the inundation and sediment transport of a tsunami similar in magnitude to the 26 December 2004 Indian Ocean tsunami over one measured and three idealized morphologies. The model is first shown to match well the observations taken at Kuala Meurisi, Sumatra, and then used to examine in detail the processes that occur during the tsunami. The model predicts that at a given cross-shore location the onshore flow accelerates rapidly to a maximum as the wavefront passes, and then gradually decelerates before reversing direction and flowing offshore. The onshore flow does not tend to zero everywhere at maximum inundation, but instead flow reversal occurs near the shoreline even as the wavefront continues to inundate landward. While some sediment is eroded by the passing wavefront, the suspension of sandy sediment is dominated by the long-duration, high-velocity backwash that occurs along the beach face and offshore of the shoreline. Some of the sediment suspended during backwash is advected shoreward by the subsequent wave, creating large spatial gradients in the suspended sediment concentrations, which may not be in equilibrium with the local hydrodynamics. The inundation and transport of sediment during a tsunami can be affected by complexities in the morphological profile and interactions between multiple waves, and many of the hydrodynamic and sediment transport processes predicted here are similar to analogous processes previously observed in the swash zone. Copyright 2011 by the American Geophysical Union.

  6. In vitro synthesis of a Major Facilitator Transporter for specific active transport across Droplet Interface Bilayers

    PubMed Central

    Findlay, Heather E.; Harris, Nicola J.; Booth, Paula J.

    2016-01-01

    Nature encapsulates reactions within membrane-bound compartments, affording sequential and spatial control over biochemical reactions. Droplet Interface Bilayers are evolving into a valuable platform to mimic this key biological feature in artificial systems. A major issue is manipulating flow across synthetic bilayers. Droplet Interface Bilayers must be functionalised, with seminal work using membrane-inserting toxins, ion channels and pumps illustrating the potential. Specific transport of biomolecules, and notably transport against a concentration gradient, across these bilayers has yet to be demonstrated. Here, we successfully incorporate the archetypal Major Facilitator Superfamily transporter, lactose permease, into Droplet Interface Bilayers and demonstrate both passive and active, uphill transport. This paves the way for controllable transport of sugars, metabolites and other essential biomolecular substrates of this ubiquitous transporter superfamily in DIB networks. Furthermore, cell-free synthesis of lactose permease during DIB formation also results in active transport across the interface bilayer. This adds a specific disaccharide transporter to the small list of integral membrane proteins that can be synthesised via in vitro transcription/translation for applications of DIB-based artificial cell systems. The introduction of a means to promote specific transport of molecules across Droplet Interface Bilayers against a concentration gradient gives a new facet to droplet networks. PMID:27996025

  7. Contemporary sediment-transport processes in submarine canyons.

    PubMed

    Puig, Pere; Palanques, Albert; Martín, Jacobo

    2014-01-01

    Submarine canyons are morphological incisions into continental margins that act as major conduits of sediment from shallow- to deep-sea regions. However, the exact mechanisms involved in sediment transfer within submarine canyons are still a subject of investigation. Several studies have provided direct information about contemporary sedimentary processes in submarine canyons that suggests different modes of transport and various triggering mechanisms. Storm-induced turbidity currents and enhanced off-shelf advection, hyperpycnal flows and failures of recently deposited fluvial sediments, dense shelf-water cascading, canyon-flank failures, and trawling-induced resuspension largely dominate present-day sediment transfer through canyons. Additionally, internal waves periodically resuspend ephemeral deposits within canyons and contribute to dispersing particles or retaining and accumulating them in specific regions. These transport processes commonly deposit sediments in the upper- and middle-canyon reaches for decades or centuries before being completely or partially flushed farther down-canyon by large sediment failures.

  8. Transport Processes in the Coastal Atmospheric Boundary Layer

    DTIC Science & Technology

    2016-06-07

    coastlines or boundary layer processes at the coast. The transported constituents may be properties of the marine boundary layer, e.g. humidity, air ... pollution or aerosols, the latter both of natural and man-made origin. In particular I am interested in the cross-coast mixing potential. By this I mean...speed maximas. Also some properties of the coastal marine air , e.g. the presence of aerosol and low clouds, are detrimental to remote sensing based on

  9. Nonlinear closure relations theory for transport processes in nonequilibrium systems.

    PubMed

    Sonnino, Giorgio

    2009-05-01

    A decade ago, a macroscopic theory for closure relations has been proposed for systems out of Onsager's region. This theory is referred to as the thermodynamic field theory (TFT). The aim of this work was to determine the nonlinear flux-force relations that respect the thermodynamic theorems for systems far from equilibrium. We propose a formulation of the TFT where one of the basic restrictions, namely, the closed-form solution for the skew-symmetric piece of the transport coefficients, has been removed. In addition, the general covariance principle is replaced by the De Donder-Prigogine thermodynamic covariance principle (TCP). The introduction of TCP requires the application of an appropriate mathematical formalism, which is referred to as the entropy-covariant formalism. By geometrical arguments, we prove the validity of the Glansdorff-Prigogine universal criterion of evolution. A new set of closure equations determining the nonlinear corrections to the linear ("Onsager") transport coefficients is also derived. The geometry of the thermodynamic space is non-Riemannian. However, it tends to be Riemannian for high values of the entropy production. In this limit, we recover the transport equations found by the old theory. Applications of our approach to transport in magnetically confined plasmas, materials submitted to temperature, and electric potential gradients or to unimolecular triangular chemical reactions can be found at references cited herein. Transport processes in tokamak plasmas are of particular interest. In this case, even in the absence of turbulence, the state of the plasma remains close to (but, it is not in) a state of local equilibrium. This prevents the transport relations from being linear.

  10. An Abiotic Glass-Bead Collector Exhibiting Active Transport

    NASA Astrophysics Data System (ADS)

    Goto, Youhei; Kanda, Masato; Yamamoto, Daigo; Shioi, Akihisa

    2015-09-01

    Animals relocate objects as needed by active motion. Active transport is ubiquitous in living organisms but has been difficult to realize in abiotic systems. Here we show that a self-propelled droplet can gather scattered beads toward one place on a floor and sweep it clean. This is a biomimetic active transport with loadings and unloadings, because the transport was performed by a carrier and the motion of the carrier was maintained by the energy of the chemical reaction. The oil droplet produced fluctuation of the local number density of the beads on the floor, followed by its autocatalytic growth. This mechanism may inspire the technologies based on active transport wherein chemical and physical substances migrate as in living organisms.

  11. Regulation of airway surface liquid volume and mucus transport by active ion transport.

    PubMed

    Tarran, Robert

    2004-01-01

    Mucus clearance is an important component of the lung's innate defense against disease, and the ability of the airways to clear mucus is strongly dependent on the volume of liquid on airway surfaces. Whether airway surface liquid (ASL) volume is maintained by passive surface forces or by active ion transport is controversial yet crucial to the understanding of how this system operates in both health and disease. In support of active ion transport being the major determinant of ASL volume, we have demonstrated that normal airway epithelia sense and autoregulate ASL height (volume) by adjusting the rates of Na+ absorption and Cl- secretion to maintain mucus transport.

  12. Quantifying solute transport processes: are chemically "conservative" tracers electrically conservative?

    USGS Publications Warehouse

    Singha, Kamini; Li, Li; Day-Lewis, Frederick D.; Regberg, Aaron B.

    2012-01-01

    The concept of a nonreactive or conservative tracer, commonly invoked in investigations of solute transport, requires additional study in the context of electrical geophysical monitoring. Tracers that are commonly considered conservative may undergo reactive processes, such as ion exchange, thus changing the aqueous composition of the system. As a result, the measured electrical conductivity may reflect not only solute transport but also reactive processes. We have evaluated the impacts of ion exchange reactions, rate-limited mass transfer, and surface conduction on quantifying tracer mass, mean arrival time, and temporal variance in laboratory-scale column experiments. Numerical examples showed that (1) ion exchange can lead to resistivity-estimated tracer mass, velocity, and dispersivity that may be inaccurate; (2) mass transfer leads to an overestimate in the mobile tracer mass and an underestimate in velocity when using electrical methods; and (3) surface conductance does not notably affect estimated moments when high-concentration tracers are used, although this phenomenon may be important at low concentrations or in sediments with high and/or spatially variable cation-exchange capacity. In all cases, colocated groundwater concentration measurements are of high importance for interpreting geophysical data with respect to the controlling transport processes of interest.

  13. A general method for determining secondary active transporter substrate stoichiometry

    PubMed Central

    Fitzgerald, Gabriel A; Mulligan, Christopher; Mindell, Joseph A

    2017-01-01

    The number of ions required to drive substrate transport through a secondary active transporter determines the protein’s ability to create a substrate gradient, a feature essential to its physiological function, and places fundamental constraints on the transporter’s mechanism. Stoichiometry is known for a wide array of mammalian transporters, but, due to a lack of readily available tools, not for most of the prokaryotic transporters for which high-resolution structures are available. Here, we describe a general method for using radiolabeled substrate flux assays to determine coupling stoichiometries of electrogenic secondary active transporters reconstituted in proteoliposomes by measuring transporter equilibrium potentials. We demonstrate the utility of this method by determining the coupling stoichiometry of VcINDY, a bacterial Na+-coupled succinate transporter, and further validate it by confirming the coupling stoichiometry of vSGLT, a bacterial sugar transporter. This robust thermodynamic method should be especially useful in probing the mechanisms of transporters with available structures. DOI: http://dx.doi.org/10.7554/eLife.21016.001 PMID:28121290

  14. Active transportation safety features around schools in Canada.

    PubMed

    Pinkerton, Bryn; Rosu, Andrei; Janssen, Ian; Pickett, William

    2013-10-31

    The purpose of this study was to describe the presence and quality of active transportation safety features in Canadian school environments that relate to pedestrian and bicycle safety. Variations in these features and associated traffic concerns as perceived by school administrators were examined by geographic status and school type. The study was based on schools that participated in 2009/2010 Health Behaviour in School-aged Children (HBSC) survey. ArcGIS software version 10 and Google Earth were used to assess the presence and quality of ten different active transportation safety features. Findings suggest that there are crosswalks and good sidewalk coverage in the environments surrounding most Canadian schools, but a dearth of bicycle lanes and other traffic calming measures (e.g., speed bumps, traffic chokers). Significant urban/rural inequities exist with a greater prevalence of sidewalk coverage, crosswalks, traffic medians, and speed bumps in urban areas. With the exception of bicycle lanes, the active transportation safety features that were present were generally rated as high quality. Traffic was more of a concern to administrators in urban areas. This study provides novel information about active transportation safety features in Canadian school environments. This information could help guide public health efforts aimed at increasing active transportation levels while simultaneously decreasing active transportation injuries.

  15. Active Transportation Safety Features around Schools in Canada

    PubMed Central

    Pinkerton, Bryn; Rosu, Andrei; Janssen, Ian; Pickett, William

    2013-01-01

    The purpose of this study was to describe the presence and quality of active transportation safety features in Canadian school environments that relate to pedestrian and bicycle safety. Variations in these features and associated traffic concerns as perceived by school administrators were examined by geographic status and school type. The study was based on schools that participated in 2009/2010 Health Behaviour in School-aged Children (HBSC) survey. ArcGIS software version 10 and Google Earth were used to assess the presence and quality of ten different active transportation safety features. Findings suggest that there are crosswalks and good sidewalk coverage in the environments surrounding most Canadian schools, but a dearth of bicycle lanes and other traffic calming measures (e.g., speed bumps, traffic chokers). Significant urban/rural inequities exist with a greater prevalence of sidewalk coverage, crosswalks, traffic medians, and speed bumps in urban areas. With the exception of bicycle lanes, the active transportation safety features that were present were generally rated as high quality. Traffic was more of a concern to administrators in urban areas. This study provides novel information about active transportation safety features in Canadian school environments. This information could help guide public health efforts aimed at increasing active transportation levels while simultaneously decreasing active transportation injuries. PMID:24185844

  16. Entropic Ratchet transport of interacting active Brownian particles

    SciTech Connect

    Ai, Bao-Quan; He, Ya-Feng; Zhong, Wei-Rong

    2014-11-21

    Directed transport of interacting active (self-propelled) Brownian particles is numerically investigated in confined geometries (entropic barriers). The self-propelled velocity can break thermodynamical equilibrium and induce the directed transport. It is found that the interaction between active particles can greatly affect the ratchet transport. For attractive particles, on increasing the interaction strength, the average velocity first decreases to its minima, then increases, and finally decreases to zero. For repulsive particles, when the interaction is very weak, there exists a critical interaction at which the average velocity is minimal, nearly tends to zero, however, for the strong interaction, the average velocity is independent of the interaction.

  17. Analytical model of reactive transport processes with spatially variable coefficients.

    PubMed

    Simpson, Matthew J; Morrow, Liam C

    2015-05-01

    Analytical solutions of partial differential equation (PDE) models describing reactive transport phenomena in saturated porous media are often used as screening tools to provide insight into contaminant fate and transport processes. While many practical modelling scenarios involve spatially variable coefficients, such as spatially variable flow velocity, v(x), or spatially variable decay rate, k(x), most analytical models deal with constant coefficients. Here we present a framework for constructing exact solutions of PDE models of reactive transport. Our approach is relevant for advection-dominant problems, and is based on a regular perturbation technique. We present a description of the solution technique for a range of one-dimensional scenarios involving constant and variable coefficients, and we show that the solutions compare well with numerical approximations. Our general approach applies to a range of initial conditions and various forms of v(x) and k(x). Instead of simply documenting specific solutions for particular cases, we present a symbolic worksheet, as supplementary material, which enables the solution to be evaluated for different choices of the initial condition, v(x) and k(x). We also discuss how the technique generalizes to apply to models of coupled multispecies reactive transport as well as higher dimensional problems.

  18. Parallel Activation in Bilingual Phonological Processing

    ERIC Educational Resources Information Center

    Lee, Su-Yeon

    2011-01-01

    In bilingual language processing, the parallel activation hypothesis suggests that bilinguals activate their two languages simultaneously during language processing. Support for the parallel activation mainly comes from studies of lexical (word-form) processing, with relatively less attention to phonological (sound) processing. According to…

  19. Active urea transport in lower vertebrates and mammals.

    PubMed

    Bankir, Lise

    2014-01-01

    Some unicellular organisms can take up urea from the surrounding fluids by an uphill pumping mechanism. Several active (energy-dependent) urea transporters (AUTs) have been cloned in these organisms. Functional studies show that active urea transport also occurs in elasmobranchs, amphibians, and mammals. In the two former groups, active urea transport may serve to conserve urea in body fluids in order to balance external high ambient osmolarity or prevent desiccation. In mammals, active urea transport may be associated with the need to either store and/or reuse nitrogen in the case of low nitrogen supply, or to excrete nitrogen efficiently in the case of excess nitrogen intake. There are probably two different families of AUTs, one with a high capacity able to establish only a relatively modest transepithelial concentration difference (renal tubule of some frogs, pars recta of the mammalian kidney, early inner medullary collecting duct in some mammals eating protein-poor diets) and others with a low capacity but able to maintain a high transepithelial concentration difference that has been created by another mechanism or in another organ (elasmobranch gills, ventral skin of some toads, and maybe mammalian urinary bladder). Functional characterization of these transporters shows that some are coupled to sodium (symports or antiports) while others are sodium-independent. In humans, only one genetic anomaly, with a mild phenotype (familial azotemia), is suspected to concern one of these transporters. In spite of abundant functional evidence for such transporters in higher organisms, none have been molecularly identified yet.

  20. Development of active-transport membrane devices

    SciTech Connect

    Laciak, D.V.

    1994-07-01

    This report introduces the concept of Air Products` AT membranes for the separation of NH{sub 3} and CO{sub 2} from process gas streams and presents results from the first year fabrication concept development studies.

  1. Hyporheic flow and transport processes: Mechanisms, models, and biogeochemical implications

    NASA Astrophysics Data System (ADS)

    Boano, F.; Harvey, J. W.; Marion, A.; Packman, A. I.; Revelli, R.; Ridolfi, L.; Wörman, A.

    2014-12-01

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed.

  2. Hyporheic flow and transport processes: mechanisms, models, and biogeochemical implications

    USGS Publications Warehouse

    Boano, Fulvio; Harvey, Judson W.; Marion, Andrea; Packman, Aaron I.; Revelli, Roberto; Ridolfi, Luca; Anders, Wörman

    2014-01-01

    Fifty years of hyporheic zone research have shown the important role played by the hyporheic zone as an interface between groundwater and surface waters. However, it is only in the last two decades that what began as an empirical science has become a mechanistic science devoted to modeling studies of the complex fluid dynamical and biogeochemical mechanisms occurring in the hyporheic zone. These efforts have led to the picture of surface-subsurface water interactions as regulators of the form and function of fluvial ecosystems. Rather than being isolated systems, surface water bodies continuously interact with the subsurface. Exploration of hyporheic zone processes has led to a new appreciation of their wide reaching consequences for water quality and stream ecology. Modern research aims toward a unified approach, in which processes occurring in the hyporheic zone are key elements for the appreciation, management, and restoration of the whole river environment. In this unifying context, this review summarizes results from modeling studies and field observations about flow and transport processes in the hyporheic zone and describes the theories proposed in hydrology and fluid dynamics developed to quantitatively model and predict the hyporheic transport of water, heat, and dissolved and suspended compounds from sediment grain scale up to the watershed scale. The implications of these processes for stream biogeochemistry and ecology are also discussed."

  3. Condensation and transport in the totally asymmetric inclusion process (TASIP)

    NASA Astrophysics Data System (ADS)

    Knebel, Johannes; Weber, Markus F.; Krueger, Torben; Frey, Erwin

    Transport phenomena are often modeled by the hopping of particles on regular lattices or networks. Such models describe, e.g., the exclusive movement of molecular motors along microtubules: no two motors may occupy the same site. In our work, we study inclusion processes that are the bosonic analogues of the fermionic exclusion processes. In inclusion processes, many particles may occupy a single site and hopping rates depend linearly on the occupation of departure and arrival sites. Particles thus attract other particles to their own site. Condensation occurs when particles collectively cluster in one or multiple sites, whereas other sites become depleted.We showed that inclusion processes describe both the selection of strategies in evolutionary zero-sum games and the condensation of non-interacting bosons into multiple quantum states in driven-dissipative systems. The condensation is captured by the antisymmetric Lotka-Volterra equation (ALVE), which constitutes a nonlinearly coupled dynamical system. We derived an algebraic method to analyze the ALVE and to determine the condensates. Our approach allows for the design of networks that result in condensates with oscillating occupations, and yields insight into the interplay between network topology and transport properties. Deutsche Forschungsgemeinschaft (SFB-TR12), German Excellence Initiative (Nanosystems Initiative Munich), Center for NanoScience Munich.

  4. Convection in the Physical Vapor Transport Process. 1; Thermal

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.

    1994-01-01

    The effects of convection on diffusive-convective physical vapor transport process are examined computationally. We analyze conditions ranging from typical laboratory conditions to conditions achievable only in a low gravity environment. This corresponds to thermal Rayleigh numbers Ra(sub tau) ranging from 1.80 x 10 to 1.92 x 10(exp 6). Our results indicate that the effect of the sublimation and condensation fluxes at the boundaries is to increase the threshold of instability. For typical ground based conditions, time dependent oscillatory convection can occur. This results in unsteady transport, and non-uniform temperature and concentration gradients at the crystal interface. Spectral analysis of the flow field shows parametric regions exhibiting both an oscillatory approach to steady state and a chaotic transient to a periodic state. Low gravity conditions stabilize the flow field. Convective effects are effectively reduced, thus resulting in uniform temperature and concentration gradients at the interface, a desirable condition for crystal growth.

  5. Convection in the Physical Vapor Transport Process-I: Thermal

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.

    1994-01-01

    The effects of convection on diffusive-convective physical vapor transport process are examined computationally. We analyze conditions ranging from typical laboratory conditions to conditions achievable only in a low gravity environment. This corresponds to thermal Rayleigh numbers Ra, ranging from 1.80 x 10 to 1.92 x 10(exp 6). Our results indicate that the effect of the sublimation and condensation fluxes at the boundaries is to increase the threshold of instability. For typical ground based conditions, time dependent oscillatory convection can occur. This results in unsteady transport, and non- uniform temperature and concentration gradients at the crystal interface. Spectral analysis of the flow field shows parametric regions exhibiting both an oscillatory approach to steady state and a chaotic transient to a periodic state. Low gravity conditions stabilize the flow field. Convective effects are effectively reduced, thus resulting in uniform temperature and concentration gradients at the interface, a desirable condition for crystal growth.

  6. Modeling of turbulent transport as a volume process

    NASA Technical Reports Server (NTRS)

    Jennings, Mark J.; Morel, Thomas

    1987-01-01

    An alternative type of modeling was proposed for the turbulent transport terms in Reynolds-averaged equations. One particular implementation of the model was considered, based on the two-point velocity correlations. The model was found to reproduce the trends but not the magnitude of the nonisotropic behavior of the turbulent transport. Some interesting insights were developed concerning the shape of the contracted two-point correlation volume. This volume is strongly deformed by mean shear from the spherical shape found in unstrained flows. Of particular interest is the finding that the shape is sharply waisted, indicating preferential lines of communication, which should have a direct effect on turbulent transfer and on other processes.

  7. CONVERTING PYROLYSIS OILS TO RENEWABLE TRANSPORT FUELS: PROCESSING CHALLENGES & OPPORTUNITIES

    SciTech Connect

    Holmgren, Jennifer; Nair, Prabhakar N.; Elliott, Douglas C.; Bain, Richard; Marinangelli, Richard

    2008-03-11

    To enable a sustained supply of biomass-based transportation fuels, the capability to process feedstocks outside the food chain must be developed. Significant industry efforts are underway to develop these new technologies, such as converting cellulosic wastes to ethanol. UOP, in partnership with U.S. Government labs, NREL and PNNL, is developing an alternate route using cellulosic feedstocks. The waste biomass is first subjected to a fast pyrolysis operation to generate pyrolysis oil (pyoil for short). Current efforts are focused on developing a thermochemical platform to convert pyoils to renewable gasoline, diesel and jet fuel. The fuels produced will be indistinguishable from their fossil fuel counterparts and, therefore, will be compatible with existing transport and distribution infrastructure.

  8. Availability Control for Means of Transport in Decisive Semi-Markov Models of Exploitation Process

    NASA Astrophysics Data System (ADS)

    Migawa, Klaudiusz

    2012-12-01

    The issues presented in this research paper refer to problems connected with the control process for exploitation implemented in the complex systems of exploitation for technical objects. The article presents the description of the method concerning the control availability for technical objects (means of transport) on the basis of the mathematical model of the exploitation process with the implementation of the decisive processes by semi-Markov. The presented method means focused on the preparing the decisive for the exploitation process for technical objects (semi-Markov model) and after that specifying the best control strategy (optimal strategy) from among possible decisive variants in accordance with the approved criterion (criteria) of the activity evaluation of the system of exploitation for technical objects. In the presented method specifying the optimal strategy for control availability in the technical objects means a choice of a sequence of control decisions made in individual states of modelled exploitation process for which the function being a criterion of evaluation reaches the extreme value. In order to choose the optimal control strategy the implementation of the genetic algorithm was chosen. The opinions were presented on the example of the exploitation process of the means of transport implemented in the real system of the bus municipal transport. The model of the exploitation process for the means of transports was prepared on the basis of the results implemented in the real transport system. The mathematical model of the exploitation process was built taking into consideration the fact that the model of the process constitutes the homogenous semi-Markov process.

  9. Caulis Sinomenii extracts activate DA/NE transporter and inhibit 5HT transporter.

    PubMed

    Zhao, Gang; Bi, Cheng; Qin, Guo-Wei; Guo, Li-He

    2009-08-01

    Caulis Sinomenii (QFT) has analgesic, sedative, and anxiolytic-like actions, and is proven effective for improving drug dependence that is known to be associated with abnormal monoaminergic transmission. We assessed whether QFT would be biologically active in functionally regulating monoamine transporters using CHO cells expressing dopamine transporter (DAT), norepinephrine transporter (NET), or serotonin transporter (SERT) (i.e. D8, N1, or S6 cells, respectively). Here, we showed that its primary extracts, such as QA, QC, QE, QD, and QB (QFT ethanol, chloroform, ethyl acetate, alkaloid-free chloroform, and alkaloid-containing chloroform extract, respectively), and secondary extracts, such as QE-2, - 3, - 5, - 7, QD-1, - 2, - 3, - 4, - 5, and QB-1, - 2, - 3, - 4, - 5 (fractioned from QE, QD, and QB, respectively), in differing degrees, either increased DA/ NE uptake by corresponding D8/N1 cells or decreased 5HT uptake by S6 cells; wherein, QE-2, QD-3, and QE-7 were potent DA/NE uptake activators while both QE-7 and QB-5 were potent 5HT uptake inhibitors. Furthermore, the enhancement of DA/NE uptake was dependent of DAT/NET activity, and the inhibition of 5HT uptake was typical of competition. Thus, QFT extracts, especially QE-2 and QE-7 (both with stronger potencies), are novel monoamine transporter modulators functioning as DAT/ NET activators and/or SERT inhibitors, and would likely improve neuropsychological disorders through regulating monoamine transporters.

  10. Driven transport on open filaments with interfilament switching processes

    NASA Astrophysics Data System (ADS)

    Ghosh, Subhadip; Pagonabarraga, Ignacio; Muhuri, Sudipto

    2017-02-01

    We study a two-filament driven lattice gas model with oppositely directed species of particles moving on two parallel filaments with filament-switching processes and particle inflow and outflow at filament ends. The filament-switching process is correlated with the occupation number of the adjacent site such that particles switch filaments with finite probability only when oppositely directed particles meet on the same filament. This model mimics some of the coarse-grained features observed in context of microtubule-(MT) based intracellular transport, wherein cellular cargo loaded and off-loaded at filament ends are transported on multiple parallel MT filaments and can switch between the parallel microtubule filaments. We focus on a regime where the filaments are weakly coupled, such that filament-switching rate of particles scale inversely as the length of the filament. We find that the interplay of (off-) loading processes at the boundaries and the filament-switching process of particles leads to some distinctive features of the system. These features includes occurrence of a variety of phases in the system with inhomogeneous density profiles including localized density shocks, density difference across the filaments, and bidirectional current flows in the system. We analyze the system by developing a mean field (MF) theory and comparing the results obtained from the MF theory with the Monte Carlo (MC) simulations of the dynamics of the system. We find that the steady-state density and current profiles of particles and the phase diagram obtained within the MF picture matches quite well with MC simulation results. These findings maybe useful for studying multifilament intracellular transport.

  11. Characterization of Transport and Solidification in the Metal Recycling Processes

    SciTech Connect

    M. A. Ebadian; R. C. Xin; Z. F. Dong

    1997-08-06

    The characterization of the transport and solidification of metal in the melting and casting processes is significant for the optimization of the radioactively contaminated metal recycling and refining processes. . In this research project, the transport process in the melting and solidification of metal was numerically predicted, and the microstructure and radionuclide distribution have been characterized by scanning electron microscope/electron diffractive X-ray (SEWEDX) analysis using cesium chloride (CSC1) as the radionuclide surrogate. In the melting and solidification process, a resistance furnace whose heating and cooling rates are program- controlled in the helium atmosphere was used. The characterization procedures included weighing, melting and solidification, weighing after solidification, sample preparation, and SEM/EDX analysis. This analytical methodology can be used to characterize metal recycling and refining products in order to evaluate the performance of the recycling process. The data obtained provide much valuable information that is necessary for the enhancement of radioactive contaminated metal decontamination and recycling technologies. The numerical method for the prediction of the melting and solidification process can be implemented in the control and monitoring system-of the melting and casting process in radioactive contaminated metal recycling. The use of radionuclide surrogates instead of real radionuclides enables the research to be performed without causing harmfid effects on people or the community. This characterization process has been conducted at the Hemispheric Center for Environmental Technology (HCET) at Florida International University since October 1995. Tests have been conducted on aluminum (Al) and copper (Cu) using cesium chloride (CSCI) as a radionuclide surrogate, and information regarding the radionuclide transfer and distribution in melting and solidification process has been obtained. The numerical simulation of

  12. The Role of Flexible Loops in Folding, Trafficking and Activity of Equilibrative Nucleoside Transporters.

    PubMed

    Aseervatham, Jaya; Tran, Lucky; Machaca, Khaled; Boudker, Olga

    2015-01-01

    Equilibrative nucleoside transporters (ENTs) are integral membrane proteins, which reside in plasma membranes of all eukaryotic cells and mediate thermodynamically downhill transport of nucleosides. This process is essential for nucleoside recycling, and also plays a key role in terminating adenosine-mediated cellular signaling. Furthermore, ENTs mediate the uptake of many drugs, including anticancer and antiviral nucleoside analogues. The structure and mechanism, by which ENTs catalyze trans-membrane transport of their substrates, remain unknown. To identify the core of the transporter needed for stability, activity, and for its correct trafficking to the plasma membrane, we have expressed human ENT deletion mutants in Xenopus laevis oocytes and determined their localization, transport properties and susceptibility to inhibition. We found that the carboxyl terminal trans-membrane segments are essential for correct protein folding and trafficking. In contrast, the soluble extracellular and intracellular loops appear to be dispensable, and must be involved in the fine-tuning of transport regulation.

  13. Classroom Activities in Transportation: Technology Education.

    ERIC Educational Resources Information Center

    Wisconsin State Dept. of Public Instruction, Madison.

    This curriculum supplement was designed to correlate directly with "A Guide to Curriculum Planning in Technology Education," published by the Wisconsin Department of Public Instruction. It is also a companion book to three other classroom activity compilations, one in each of the other three major systems of technology--manufacturing,…

  14. The connexion between active cation transport and metabolism in erythrocytes

    PubMed Central

    Whittam, R.; Ager, Margaret E.

    1965-01-01

    1. A study has been made of the dependence on the concentrations of internal Na+ and external K+ of lactate and phosphate production in human erythrocytes. 2. Lactate production was stimulated by Na+ and K+ but only when they were internal and external respectively. The stimulation was counteracted by ouabain. The production of phosphate was affected in the same way. 3. There is a quantitative correlation between these effects and those previously found for cation movements and the membrane adenosine triphosphatase. 4. It is concluded that the rate of energy production in glycolysis is partly controlled by the magnitude of active transport; the extent of this regulation is shown to vary from 25 to 75% of a basal rate that is independent of active transport. 5. The activity of the membrane adenosine triphosphatase was also compared with rates of Na+ and K+ transport. The latter were varied by altering the concentrations of internal Na+ and external K+, and by inhibiting with ouabain. 6. A threefold variation of active transport rate was accompanied by a parallel change in the membrane adenosine-triphosphatase activity. The results show a constant stoicheiometry for the number of ions moved/mol. of ATP hydrolysed, independent of the electrochemical gradient against which the ions were moved. 7. Calculations show that the amount of ATP hydrolysed would provide enough energy for the osmotic work. The results are discussed in relation to possible mechanisms for active transport. PMID:16749106

  15. Promoting physical activity and reducing climate change: opportunities to replace short car trips with active transportation.

    PubMed

    Maibach, Edward; Steg, Linda; Anable, Jillian

    2009-10-01

    Automobile use is a significant contributor to climate change, local air pollution, pedestrian injuries and deaths, declines in physical activity and obesity. A significant proportion of car use is for short trips that can relatively easily be taken with active transportation options--walking or cycling--or with public transportation. In this commentary, we review a number of immediate, practical opportunities to implement policies and programs that reduce short car trips and increase active transportation.

  16. Engineered Barrier System Degradation, Flow, and Transport Process Model Report

    SciTech Connect

    E.L. Hardin

    2000-07-17

    The Engineered Barrier System Degradation, Flow, and Transport Process Model Report (EBS PMR) is one of nine PMRs supporting the Total System Performance Assessment (TSPA) being developed by the Yucca Mountain Project for the Site Recommendation Report (SRR). The EBS PMR summarizes the development and abstraction of models for processes that govern the evolution of conditions within the emplacement drifts of a potential high-level nuclear waste repository at Yucca Mountain, Nye County, Nevada. Details of these individual models are documented in 23 supporting Analysis/Model Reports (AMRs). Nineteen of these AMRs are for process models, and the remaining 4 describe the abstraction of results for application in TSPA. The process models themselves cluster around four major topics: ''Water Distribution and Removal Model, Physical and Chemical Environment Model, Radionuclide Transport Model, and Multiscale Thermohydrologic Model''. One AMR (Engineered Barrier System-Features, Events, and Processes/Degradation Modes Analysis) summarizes the formal screening analysis used to select the Features, Events, and Processes (FEPs) included in TSPA and those excluded from further consideration. Performance of a potential Yucca Mountain high-level radioactive waste repository depends on both the natural barrier system (NBS) and the engineered barrier system (EBS) and on their interactions. Although the waste packages are generally considered as components of the EBS, the EBS as defined in the EBS PMR includes all engineered components outside the waste packages. The principal function of the EBS is to complement the geologic system in limiting the amount of water contacting nuclear waste. A number of alternatives were considered by the Project for different EBS designs that could provide better performance than the design analyzed for the Viability Assessment. The design concept selected was Enhanced Design Alternative II (EDA II).

  17. Transport equations of electrodiffusion processes in the laboratory reference frame.

    PubMed

    Garrido, Javier

    2006-02-23

    The transport equations of electrodiffusion processes use three reference frames for defining the fluxes: Fick's reference in diffusion, solvent-fixed reference in transference numbers, and laboratory fluxes in electric conductivity. The convenience of using only one reference frame is analyzed here from the point of view of the thermodynamics of irreversible processes. A relation between the fluxes of ions and solvent and the electric current density is deduced first from a mass and volume balance. This is then used to show that (i) the laboratory and Fick's diffusion coefficients are identical and (ii) the transference numbers of both the solvent and the ion in the laboratory reference frame are related. Finally, four experimental methods for the measurement of ion transference numbers are analyzed critically. New expressions for evaluating transference numbers for the moving boundary method and the chronopotentiometry technique are deduced. It is concluded that the ion transport equation in the laboratory reference frame plays a key role in the description of electrodiffusion processes.

  18. Advanced Reactors Thermal Energy Transport for Process Industries

    SciTech Connect

    P. Sabharwall; S.J. Yoon; M.G. McKellar; C. Stoots; George Griffith

    2014-07-01

    The operation temperature of advanced nuclear reactors is generally higher than commercial light water reactors and thermal energy from advanced nuclear reactor can be used for various purposes such as liquid fuel production, district heating, desalination, hydrogen production, and other process heat applications, etc. Some of the major technology challenges that must be overcome before the advanced reactors could be licensed on the reactor side are qualification of next generation of nuclear fuel, materials that can withstand higher temperature, improvement in power cycle thermal efficiency by going to combined cycles, SCO2 cycles, successful demonstration of advanced compact heat exchangers in the prototypical conditions, and from the process side application the challenge is to transport the thermal energy from the reactor to the process plant with maximum efficiency (i.e., with minimum temperature drop). The main focus of this study is on doing a parametric study of efficient heat transport system, with different coolants (mainly, water, He, and molten salts) to determine maximum possible distance that can be achieved.

  19. Active Transportation to School: Findings from a National Survey

    ERIC Educational Resources Information Center

    Fulton, Janet E.; Shisler, Jessica L.; Yore, Michelle M.; Caspersen, Carl J.

    2005-01-01

    In the past, active transportation to school offered an important source of daily physical activity for youth; more recently, however, factors related to distance, safety, or physical or social environments may have contributed to the proportion of children who travel to school by motorized vehicle. The authors examine the characteristics of…

  20. Mass-transport processes at the steel-enamel interface

    NASA Astrophysics Data System (ADS)

    Yang, X.; Jha, A.; Cochrane, R. C.; Ali, S.

    2006-02-01

    Mass-transport processes at the enamel-steel interface were investigated by studying the rheological properties of the enamel and the microstructure of the enamel-steel interface. The thermophysical properties, e.g., the viscosity and spreading behavior of enamel were measured using the rotating bob and the sessile drop techniques, respectively. The results show that the viscosity of the enamel decreases sharply as the FeO concentration increases from 0 to 25 wt pct, while the contact angle changes with the increasing thickness of the NiO precoat. Microstructural characterization also revealed evidence for the presence of an interfacial gradient force (more specifically referred to as the Marangoni convection) confined within the 0- to 80-µm thickness at the enamel-steel interface. This force is responsible for a convective flow, which determines the formation of flow striae at the interface. The striae act as a sink for evolved gases and provide transport away from the enamel-steel interface. In addition, experimental simulation of Marangoni convection (interfacial-gradient force) was carried out by selectively doping the steel surface with excess Fe2O3 powder. The presence of convection flow was confirmed by analyzing the pattern of iron oxide particles dispersed across the surrounding enamel layers. Based on the microstructural characterization and the thermophysical data, we propose a mechanism for mass transport at the glass-steel interface.

  1. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Congestion management process in transportation... Programming § 450.320 Congestion management process in transportation management areas. (a) The transportation planning process in a TMA shall address congestion management through a process that provides for safe...

  2. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 23 Highways 1 2010-04-01 2010-04-01 false Congestion management process in transportation... Programming § 450.320 Congestion management process in transportation management areas. (a) The transportation planning process in a TMA shall address congestion management through a process that provides for safe...

  3. Substrate regulation of ascorbate transport activity in astrocytes

    SciTech Connect

    Wilson, J.X.; Jaworski, E.M.; Kulaga, A.; Dixon, S.J. )

    1990-10-01

    Astrocytes possess a concentrative L-ascorbate (vitamin C) uptake mechanism involving a Na(+)-dependent L-ascorbate transporter located in the plasma membrane. The present experiments examined the effects of deprivation and supplementation of extracellular L-ascorbate on the activity of this transport system. Initial rates of L-ascorbate uptake were measured by incubating primary cultures of rat astrocytes with L-(14C)ascorbate for 1 min at 37 degrees C. We observed that the apparent maximal rate of uptake (Vmax) increased rapidly (less than 1 h) when cultured cells were deprived of L-ascorbate. In contrast, there was no change in the apparent affinity of the transport system for L-(14C)ascorbate. The increase in Vmax was reversed by addition of L-ascorbate, but not D-isoascorbate, to the medium. The effects of external ascorbate on ascorbate transport activity were specific in that preincubation of cultures with L-ascorbate did not affect uptake of 2-deoxy-D-(3H(G))glucose. We conclude that the astroglial ascorbate transport system is modulated by changes in substrate availability. Regulation of transport activity may play a role in intracellular ascorbate homeostasis by compensating for regional differences and temporal fluctuations in external ascorbate levels.

  4. Interacting Physical and Biological Processes Affecting Nutrient Transport Through Human Dominated Landscapes

    NASA Astrophysics Data System (ADS)

    Finlay, J. C.

    2015-12-01

    Human activities increasingly dominate biogeochemical cycles of limiting nutrients on Earth. Urban and agricultural landscapes represent the largest sources of excess nutrients that drive water quality degradation. The physical structure of both urban and agricultural watersheds has been extensively modified, and these changes have large impacts on water and nutrient transport. Despite strong physical controls over nutrient transport in human dominated landscapes, biological processes play important roles in determining the fates of both nitrogen and phosphorus. This talk uses examples from research in urban and agricultural watersheds in the Midwestern USA to illustrate interactions of physical and biological controls over nutrient cycles that have shifted nitrogen (N) and phosphorus (P) sources and cycling in unexpected ways in response to management changes. In urban watersheds, efforts to improve water quality have been hindered by legacy sources of phosphorus added to storm water through transport to drainage systems by vegetation. Similarly, reductions in field erosion in agricultural watersheds have not led to major reductions in phosphorus transport, because of continued release of biological sources of P. Where management of phosphorus has been most effective in reducing eutrophication of lakes, decreases in N removal processes have led to long term increases in N concentration and transport. Together, these examples show important roles for biological processes affecting nutrient movement in highly modified landscapes. Consideration of the downstream physical and biological responses of management changes are thus critical toward identification of actions that will most effectively reduce excess nutrients watersheds and coastal zones.

  5. Features, Events and Processes in UZ Flow and Transport

    SciTech Connect

    P. Persoff

    2005-08-04

    The purpose of this report is to evaluate and document the inclusion or exclusion of the unsaturated zone (UZ) features, events, and processes (FEPs) with respect to modeling that supports the total system performance assessment (TSPA) for license application (LA) for a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either Included or Excluded, is given for each FEP, along with the technical basis for the screening decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) in 10 CFR 63.114 (d, e, and f) [DIRS 173273]. The FEPs deal with UZ flow and radionuclide transport, including climate, surface water infiltration, percolation, drift seepage, and thermally coupled processes. This analysis summarizes the implementation of each FEP in TSPA-LA (that is, how the FEP is included) and also provides the technical basis for exclusion from TSPA-LA (that is, why the FEP is excluded). This report supports TSPA-LA.

  6. Features, Events, and Processes in UZ and Transport

    SciTech Connect

    P. Persoff

    2004-11-06

    The purpose of this report is to evaluate and document the inclusion or exclusion of the unsaturated zone (UZ) features, events, and processes (FEPs) with respect to modeling that supports the total system performance assessment (TSPA) for license application (LA) for a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either ''Included'' or ''Excluded'', is given for each FEP, along with the technical basis for the screening decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) in 10 CFR 63.114 (d, e, and f) [DIRS 156605]. The FEPs deal with UZ flow and radionuclide transport, including climate, surface water infiltration, percolation, drift seepage, and thermally coupled processes. This analysis summarizes the implementation of each FEP in TSPA-LA (that is, how the FEP is included) and also provides the technical basis for exclusion from TSPA-LA (that is, why the FEP is excluded). This report supports TSPA-LA.

  7. Efficient processing of transportation surveillance videos in the compressed domain

    NASA Astrophysics Data System (ADS)

    Bulan, Orhan; Bernal, Edgar A.; Loce, Robert P.

    2013-10-01

    Video surveillance is used extensively in intelligent transportation systems to enforce laws, collect tolls, and regularize traffic flow. Benefits to society include reduced fuel consumption and emissions, improved safety, and reduced traffic congestion. These video cameras installed at traffic lights, highways, toll booths, etc., continuously capture video and hence generate a vast amount of data that are stored in large databases. The captured video is typically compressed before being transmitted and/or stored. While all the archived information is present in the compressed video, most current applications operate on uncompressed video. The aim is to improve the efficiency of processing by utilizing features of the compression process and the compressed video stream. Key methods that are employed involve intelligent selection of reference frames (I-frames) and exploitation of the compression motion vectors. Although specific applications in the transportation imaging domain are presented, the methods proposed here can generally impact the ability to mine vast amounts of video data for usable information in many diverse settings. Applications presented include rapid search for target vehicles (Amber Alert, Silver Alert, stolen car, etc.), vehicle counting, stop sign/light enforcement, and vehicle speed estimation.

  8. Analysis of suspended solids transport processes in primary settling tanks.

    PubMed

    Patziger, Miklós; Kiss, Katalin

    2015-01-01

    The paper shows the results of a long-term research comprising FLUENT-based numerical modeling, in situ measurements and laboratory tests to analyze suspended solids (SS) transport processes in primary settling tanks (PSTs). The investigated PST was one of the rectangular horizontal flow PSTs at a large municipal wastewater treatment plant (WWTP) of a capacity of 500,000 population equivalent. Many middle-sized and large WWTPs are equipped with such PSTs. The numerical PST model was calibrated and validated based on the results of comprehensive in situ flow and SS concentration measurements from low (5 m/h) up to quite high surface overflow rates of 9.5 and 13.0 m/h and on settling and other laboratory tests. The calibrated and validated PST model was also successfully used for evaluation of some slight modifications of the inlet geometry (removing lamellas, installing a flocculation 'box', shifting the inlet into a 'bottom-near' or into a 'high' position), which largely affect PST behavior and performance. The investigations provided detailed insight into the flow and SS transport processes within the investigated PST, which strongly contributes to hydrodynamically driven design and upgrading of PSTs.

  9. Memoryless self-reinforcing directionality in endosomal active transport within living cells

    NASA Astrophysics Data System (ADS)

    Chen, Kejia; Wang, Bo; Granick, Steve

    2015-06-01

    In contrast to Brownian transport, the active motility of microbes, cells, animals and even humans often follows another random process known as truncated Lévy walk. These stochastic motions are characterized by clustered small steps and intermittent longer jumps that often extend towards the size of the entire system. As there are repeated suggestions, although disagreement, that Lévy walks have functional advantages over Brownian motion in random searching and transport kinetics, their intentional engineering into active materials could be useful. Here, we show experimentally in the classic active matter system of intracellular trafficking that Brownian-like steps self-organize into truncated Lévy walks through an apparent time-independent positive feedback such that directional persistence increases with the distance travelled persistently. A molecular model that allows the maximum output of the active propelling forces to fluctuate slowly fits the experiments quantitatively. Our findings offer design principles for programming efficient transport in active materials.

  10. Neuroinflammation activates efflux transport by NFκB

    PubMed Central

    Yu, Chuanhui; Argyropoulos, George; Zhang, Yan; Kastin, Abba J.; Hsuchou, Hung; Pan, Weihong

    2009-01-01

    Background/aims Although it is known that drug delivery across the blood-brain barrier (BBB) may be hampered by efflux transport activity of the multidrug resistance (mdr) gene product P-glycoprotein, it is not clear how inflammation regulates efflux transporters. In rat brain endothelial (RBE4) cells of BBB origin, the proinflammatory cytokine TNF mainly induces transcriptional upregulation of mdr1b, and to a lesser extent mdr1a, resulting in greater efflux of the substrates (Yu C et al., Cell Physiol Biochem, 2007). This study further determined the mechanisms by which TNF activates mdr1b promoter activity. Methods/Results Luciferase reporter assays and DNA binding studies show that (a) maximal basal promoter activity was conferred by a 476 bp sequence upstream to the mdr1b transcriptional initiation site; (2) TNF induced upregulation of promoter activity by NFkB nuclear translocation; and (3) the NFκB binding site of the mdr1b promoter was solely responsible for basal and TNF-activated gene transcription, whereas the p53 binding site was not involved. Binding of the p65 subunit of NFκB to nuclear DNA from RBE4 cells was shown by electrophoretic mobility shift assay and chromatin immunoprecipitation assays. Conclusion Thus, NFκB mediated TNF-induced upregulation of mdr1b promoter activity, illustrating how inflammation activates BBB efflux transport. PMID:19088456

  11. Dopamine transporter occupancy by RTI-55, inhibition of dopamine transport and stimulation of locomotor activity

    SciTech Connect

    Gatley, S.J.; Gifford, A.N.; Volkow, N.D.

    1997-05-01

    Cocaine analogs such as RTI-55 (or {beta}CIT) with a higher affinity for the DAT are potentially useful as therapeutic drugs in cocaine abuse as well as for radiopharmaceutical use. Previously we showed that in mice RTI-55 (2 mg/Kg, i/p) reduced H-3 cocaine striatum-to-cerebellum ratios (St/Cb, {lg_bullet}) from 1.6 to 1.2 at 3 h after administration, with recovery by 12 h. In the present study we demonstrate a very similar time-course for transport {triangle} measured in striatal homo within 2 min of sacrifice. The maximum inhibition of uptake at about 1 h corresponded to about 80% of the control uptake rate, similar to the percent reduction in St/Cb. The time-course of the effect of this dose of RTI-55 on locomotor activity ({sq_bullet}) was complex, with a drop in the activity measure at 7 h, after a further injection of RTI-55, but activity remained higher than in saline controls. In spite of this complexity, which may be associated with stereotypies and/or exhaustion, the duration of increased activity is consistent with the duration of transporter blockade. These experiments support the notion that PET/SPECT measures of transporter occupancy accurately reflect transporter inhibition.

  12. Features, Events, and Processes in SZ Flow and Transport

    SciTech Connect

    K. Economy

    2004-11-16

    This analysis report evaluates and documents the inclusion or exclusion of the saturated zone (SZ) features, events, and processes (FEPs) with respect to modeling used to support the total system performance assessment (TSPA) for license application (LA) of a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either ''Included'' or ''Excluded'', is given for each FEP along with the technical basis for the decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.114 (d), (e), (f) (DIRS 156605). This scientific report focuses on FEP analysis of flow and transport issues relevant to the SZ (e.g., fracture flow in volcanic units, anisotropy, radionuclide transport on colloids, etc.) to be considered in the TSPA model for the LA. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded).

  13. Features, Events, and Processes in SZ Flow and Transport

    SciTech Connect

    S. Kuzio

    2005-08-20

    This analysis report evaluates and documents the inclusion or exclusion of the saturated zone (SZ) features, events, and processes (FEPs) with respect to modeling used to support the total system performance assessment (TSPA) for license application (LA) of a nuclear waste repository at Yucca Mountain, Nevada. A screening decision, either Included or Excluded, is given for each FEP along with the technical basis for the decision. This information is required by the U.S. Nuclear Regulatory Commission (NRC) at 10 CFR 63.11(d), (e), (f) [DIRS 173273]. This scientific report focuses on FEP analysis of flow and transport issues relevant to the SZ (e.g., fracture flow in volcanic units, anisotropy, radionuclide transport on colloids, etc.) to be considered in the TSPA model for the LA. For included FEPs, this analysis summarizes the implementation of the FEP in TSPA-LA (i.e., how the FEP is included). For excluded FEPs, this analysis provides the technical basis for exclusion from TSPA-LA (i.e., why the FEP is excluded).

  14. Genetic and chemical reductions in protein phosphatase activity alter auxin transport, gravity response, and lateral root growth

    NASA Technical Reports Server (NTRS)

    Rashotte, A. M.; DeLong, A.; Muday, G. K.; Brown, C. S. (Principal Investigator)

    2001-01-01

    Auxin transport is required for important growth and developmental processes in plants, including gravity response and lateral root growth. Several lines of evidence suggest that reversible protein phosphorylation regulates auxin transport. Arabidopsis rcn1 mutant seedlings exhibit reduced protein phosphatase 2A activity and defects in differential cell elongation. Here we report that reduced phosphatase activity alters auxin transport and dependent physiological processes in the seedling root. Root basipetal transport was increased in rcn1 or phosphatase inhibitor-treated seedlings but showed normal sensitivity to the auxin transport inhibitor naphthylphthalamic acid (NPA). Phosphatase inhibition reduced root gravity response and delayed the establishment of differential auxin-induced gene expression across a gravity-stimulated root tip. An NPA treatment that reduced basipetal transport in rcn1 and cantharidin-treated wild-type plants also restored a normal gravity response and asymmetric auxin-induced gene expression, indicating that increased basipetal auxin transport impedes gravitropism. Increased auxin transport in rcn1 or phosphatase inhibitor-treated seedlings did not require the AGR1/EIR1/PIN2/WAV6 or AUX1 gene products. In contrast to basipetal transport, root acropetal transport was normal in phosphatase-inhibited seedlings in the absence of NPA, although it showed reduced NPA sensitivity. Lateral root growth also exhibited reduced NPA sensitivity in rcn1 seedlings, consistent with acropetal transport controlling lateral root growth. These results support the role of protein phosphorylation in regulating auxin transport and suggest that the acropetal and basipetal auxin transport streams are differentially regulated.

  15. Transport of active ellipsoidal particles in ratchet potentials

    SciTech Connect

    Ai, Bao-Quan Wu, Jian-Chun

    2014-03-07

    Rectified transport of active ellipsoidal particles is numerically investigated in a two-dimensional asymmetric potential. The out-of-equilibrium condition for the active particle is an intrinsic property, which can break thermodynamical equilibrium and induce the directed transport. It is found that the perfect sphere particle can facilitate the rectification, while the needlelike particle destroys the directed transport. There exist optimized values of the parameters (the self-propelled velocity, the torque acting on the body) at which the average velocity takes its maximal value. For the ellipsoidal particle with not large asymmetric parameter, the average velocity decreases with increasing the rotational diffusion rate, while for the needlelike particle (very large asymmetric parameter), the average velocity is a peaked function of the rotational diffusion rate. By introducing a finite load, particles with different shapes (or different self-propelled velocities) will move to the opposite directions, which is able to separate particles of different shapes (or different self-propelled velocities)

  16. Geochemical constraints on magma formation and transport processes

    NASA Astrophysics Data System (ADS)

    Shorttle, O.; Antoshechkina, P. M.; Dasgupta, R.; Rudge, J. F.; Asimow, P. D.

    2015-12-01

    Primitive basalts provide an invaluable probe of the mantle's thermo-chemical structure. What these samples show is that the Earth's interior is widely variable in its trace element, isotopic and even major element composition, on the km to the hemispherical scale. This heterogeneity has profound implications for not only the history of the solid Earth, but the oceans and atmosphere as well, as it represents ~4 billions of years of elemental transport back into the mantle via subduction recycling of oceanic crustal to mantle sections. Reconstructing planetary evolution through the volcanic record of mantle composition is therefore a primary aim of igneous geochemistry. However, between the solid mantle and our chemical analyses lie a series of melt generation, aggregation and transport processes, themselves poorly understood, that are potentially critical in controlling the amplitude and style of chemical heterogeneity preserved in an erupted basalt. If these processes are also sensitive to mantle potential temperature, the degree of melting and the presence of lithological heterogeneity, then the geochemical record may not only be biased as a whole, but biased in a relative sense between different geodynamic settings: such a dichotomy may be represented by ocean islands and mid-ocean ridges. Here we combine observational and modelling approaches to understand how varying conditions of melt generation and transport affect basalt chemical variability. Focusing first on Iceland, we combine new and existing melt inclusion data to investigate how chemical variability may be controlled by tectonic parameters (on versus off rift) and source enrichment. We find that on Iceland the key parameter controlling variability is enrichment, with the most enriched basalts preserving diminished variability compared with more depleted eruptions. However, on a larger scale enriched sources preserve the greatest variability: we see this both in terms of the greater variability of

  17. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 49 Transportation 1 2013-10-01 2013-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61...

  18. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 49 Transportation 1 2014-10-01 2014-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61...

  19. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 49 Transportation 1 2012-10-01 2012-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61...

  20. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 49 Transportation 1 2011-10-01 2011-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61...

  1. 49 CFR 37.61 - Public transportation programs and activities in existing facilities.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 49 Transportation 1 2010-10-01 2010-10-01 false Public transportation programs and activities in existing facilities. 37.61 Section 37.61 Transportation Office of the Secretary of Transportation TRANSPORTATION SERVICES FOR INDIVIDUALS WITH DISABILITIES (ADA) Transportation Facilities § 37.61...

  2. Modeling transport phenomena and uncertainty quantification in solidification processes

    NASA Astrophysics Data System (ADS)

    Fezi, Kyle S.

    Direct chill (DC) casting is the primary processing route for wrought aluminum alloys. This semicontinuous process consists of primary cooling as the metal is pulled through a water cooled mold followed by secondary cooling with a water jet spray and free falling water. To gain insight into this complex solidification process, a fully transient model of DC casting was developed to predict the transport phenomena of aluminum alloys for various conditions. This model is capable of solving mixture mass, momentum, energy, and species conservation equations during multicomponent solidification. Various DC casting process parameters were examined for their effect on transport phenomena predictions in an alloy of commercial interest (aluminum alloy 7050). The practice of placing a wiper to divert cooling water from the ingot surface was studied and the results showed that placement closer to the mold causes remelting at the surface and increases susceptibility to bleed outs. Numerical models of metal alloy solidification, like the one previously mentioned, are used to gain insight into physical phenomena that cannot be observed experimentally. However, uncertainty in model inputs cause uncertainty in results and those insights. The analysis of model assumptions and probable input variability on the level of uncertainty in model predictions has not been calculated in solidification modeling as yet. As a step towards understanding the effect of uncertain inputs on solidification modeling, uncertainty quantification (UQ) and sensitivity analysis were first performed on a transient solidification model of a simple binary alloy (Al-4.5wt.%Cu) in a rectangular cavity with both columnar and equiaxed solid growth models. This analysis was followed by quantifying the uncertainty in predictions from the recently developed transient DC casting model. The PRISM Uncertainty Quantification (PUQ) framework quantified the uncertainty and sensitivity in macrosegregation, solidification

  3. Proton Gradients and Proton-Dependent Transport Processes in the Chloroplast

    PubMed Central

    Höhner, Ricarda; Aboukila, Ali; Kunz, Hans-Henning; Venema, Kees

    2016-01-01

    Proton gradients are fundamental to chloroplast function. Across thylakoid membranes, the light induced -proton gradient is essential for ATP synthesis. As a result of proton pumping into the thylakoid lumen, an alkaline stromal pH develops, which is required for full activation of pH-dependent Calvin Benson cycle enzymes. This implies that a pH gradient between the cytosol (pH 7) and the stroma (pH 8) is established upon illumination. To maintain this pH gradient chloroplasts actively extrude protons. More than 30 years ago it was already established that these proton fluxes are electrically counterbalanced by Mg2+, K+, or Cl- fluxes, but only recently the first transport systems that regulate the pH gradient were identified. Notably several (Na+,K+)/H+ antiporter systems where identified, that play a role in pH gradient regulation, ion homeostasis, osmoregulation, or coupling of secondary active transport. The established pH gradients are important to drive uptake of essential ions and solutes, but not many transporters involved have been identified to date. In this mini review we summarize the current status in the field and the open questions that need to be addressed in order to understand how pH gradients are maintained, how this is interconnected with other transport processes and what this means for chloroplast function. PMID:26973667

  4. Regional differences in rat conjunctival ion transport activities.

    PubMed

    Yu, Dongfang; Thelin, William R; Rogers, Troy D; Stutts, M Jackson; Randell, Scott H; Grubb, Barbara R; Boucher, Richard C

    2012-10-01

    Active ion transport and coupled osmotic water flow are essential to maintain ocular surface health. We investigated regional differences in the ion transport activities of the rat conjunctivas and compared these activities with those of cornea and lacrimal gland. The epithelial sodium channel (ENaC), sodium/glucose cotransporter 1 (Slc5a1), transmembrane protein 16 (Tmem16a, b, f, and g), cystic fibrosis transmembrane conductance regulator (Cftr), and mucin (Muc4, 5ac, and 5b) mRNA expression was characterized by RT-PCR. ENaC proteins were measured by Western blot. Prespecified regions (palpebral, fornical, and bulbar) of freshly isolated conjunctival tissues and cell cultures were studied electrophysiologically with Ussing chambers. The transepithelial electrical potential difference (PD) of the ocular surface was also measured in vivo. The effect of amiloride and UTP on the tear volume was evaluated in lacrimal gland excised rats. All selected genes were detected but with different expression patterns. We detected αENaC protein in all tissues, βENaC in palpebral and fornical conjunctiva, and γENaC in all tissues except lacrimal glands. Electrophysiological studies of conjunctival tissues and cell cultures identified functional ENaC, SLC5A1, CFTR, and TMEM16. Fornical conjunctiva exhibited the most active ion transport under basal conditions amongst conjunctival regions. PD measurements confirmed functional ENaC-mediated Na(+) transport on the ocular surface. Amiloride and UTP increased tear volume in lacrimal gland excised rats. This study demonstrated that the different regions of the conjunctiva exhibited a spectrum of ion transport activities. Understanding the specific functions of distinct regions of the conjunctiva may foster a better understanding of the physiology maintaining hydration of the ocular surface.

  5. Unraveling fatty acid transport and activation mechanisms in Yarrowia lipolytica.

    PubMed

    Dulermo, Rémi; Gamboa-Meléndez, Heber; Ledesma-Amaro, Rodrigo; Thévenieau, France; Nicaud, Jean-Marc

    2015-09-01

    Fatty acid (FA) transport and activation have been extensively studied in the model yeast species Saccharomyces cerevisiae but have rarely been examined in oleaginous yeasts, such as Yarrowia lipolytica. Because the latter begins to be used in biodiesel production, understanding its FA transport and activation mechanisms is essential. We found that Y. lipolytica has FA transport and activation proteins similar to those of S. cerevisiae (Faa1p, Pxa1p, Pxa2p, Ant1p) but mechanism of FA peroxisomal transport and activation differs greatly with that of S. cerevisiae. While the ScPxa1p/ScPxa2p heterodimer is essential for growth on long-chain FAs, ΔYlpxa1 ΔYlpxa2 is not impaired for growth on FAs. Meanwhile, ScAnt1p and YlAnt1p are both essential for yeast growth on medium-chain FAs, suggesting they function similarly. Interestingly, we found that the ΔYlpxa1 ΔYlpxa2 ΔYlant1 mutant was unable to grow on short-, medium-, or long-chain FAs, suggesting that YlPxa1p, YlPxa2p, and YlAnt1p belong to two different FA degradation pathways. We also found that YlFaa1p is involved in FA storage in lipid bodies and that FA remobilization largely depended on YlFat1p, YlPxa1p and YlPxa2p. This study is the first to comprehensively examine FA intracellular transport and activation in oleaginous yeast.

  6. Regional differences in rat conjunctival ion transport activities

    PubMed Central

    Yu, Dongfang; Thelin, William R.; Rogers, Troy D.; Stutts, M. Jackson; Randell, Scott H.; Grubb, Barbara R.

    2012-01-01

    Active ion transport and coupled osmotic water flow are essential to maintain ocular surface health. We investigated regional differences in the ion transport activities of the rat conjunctivas and compared these activities with those of cornea and lacrimal gland. The epithelial sodium channel (ENaC), sodium/glucose cotransporter 1 (Slc5a1), transmembrane protein 16 (Tmem16a, b, f, and g), cystic fibrosis transmembrane conductance regulator (Cftr), and mucin (Muc4, 5ac, and 5b) mRNA expression was characterized by RT-PCR. ENaC proteins were measured by Western blot. Prespecified regions (palpebral, fornical, and bulbar) of freshly isolated conjunctival tissues and cell cultures were studied electrophysiologically with Ussing chambers. The transepithelial electrical potential difference (PD) of the ocular surface was also measured in vivo. The effect of amiloride and UTP on the tear volume was evaluated in lacrimal gland excised rats. All selected genes were detected but with different expression patterns. We detected αENaC protein in all tissues, βENaC in palpebral and fornical conjunctiva, and γENaC in all tissues except lacrimal glands. Electrophysiological studies of conjunctival tissues and cell cultures identified functional ENaC, SLC5A1, CFTR, and TMEM16. Fornical conjunctiva exhibited the most active ion transport under basal conditions amongst conjunctival regions. PD measurements confirmed functional ENaC-mediated Na+ transport on the ocular surface. Amiloride and UTP increased tear volume in lacrimal gland excised rats. This study demonstrated that the different regions of the conjunctiva exhibited a spectrum of ion transport activities. Understanding the specific functions of distinct regions of the conjunctiva may foster a better understanding of the physiology maintaining hydration of the ocular surface. PMID:22814399

  7. Engineering intracellular active transport systems as in vivo biomolecular tools.

    SciTech Connect

    Bachand, George David; Carroll-Portillo, Amanda

    2006-11-01

    Active transport systems provide essential functions in terms of cell physiology and metastasis. These systems, however, are also co-opted by invading viruses, enabling directed transport of the virus to and from the cell's nucleus (i.e., the site of virus replication). Based on this concept, fundamentally new approaches for interrogating and manipulating the inner workings of living cells may be achievable by co-opting Nature's active transport systems as an in vivo biomolecular tool. The overall goal of this project was to investigate the ability to engineer kinesin-based transport systems for in vivo applications, specifically the collection of effector proteins (e.g., transcriptional regulators) within single cells. In the first part of this project, a chimeric fusion protein consisting of kinesin and a single chain variable fragment (scFv) of an antibody was successfully produced through a recombinant expression system. The kinesin-scFv retained both catalytic and antigenic functionality, enabling selective capture and transport of target antigens. The incorporation of a rabbit IgG-specific scFv into the kinesin established a generalized system for functionalizing kinesin with a wide range of target-selective antibodies raised in rabbits. The second objective was to develop methods of isolating the intact microtubule network from live cells as a platform for evaluating kinesin-based transport within the cytoskeletal architecture of a cell. Successful isolation of intact microtubule networks from two distinct cell types was demonstrated using glutaraldehyde and methanol fixation methods. This work provides a platform for inferring the ability of kinesin-scFv to function in vivo, and may also serve as a three-dimensional scaffold for evaluating and exploiting kinesin-based transport for nanotechnological applications. Overall, the technology developed in this project represents a first-step in engineering active transport system for in vivo applications. Further

  8. Morphine Induces Ubiquitin-Proteasome Activity and Glutamate Transporter Degradation*

    PubMed Central

    Yang, Liling; Wang, Shuxing; Sung, Backil; Lim, Grewo; Mao, Jianren

    2008-01-01

    Glutamate transporters play a crucial role in physiological glutamate homeostasis, neurotoxicity, and glutamatergic regulation of opioid tolerance. However, how the glutamate transporter turnover is regulated remains poorly understood. Here we show that chronic morphine exposure induced posttranscriptional down-regulation of the glutamate transporter EAAC1 in C6 glioma cells with a concurrent decrease in glutamate uptake and increase in proteasome activity, which were blocked by the selective proteasome inhibitor MG-132 or lactacystin but not the lysosomal inhibitor chloroquin. At the cellular level, chronic morphine induced the PTEN (phosphatase and tensin homolog deleted on chromosome Ten)-mediated up-regulation of the ubiquitin E3 ligase Nedd4 via cAMP/protein kinase A signaling, leading to EAAC1 ubiquitination and proteasomal degradation. Either Nedd4 or PTEN knockdown with small interfering RNA prevented the morphine-induced EAAC1 degradation and decreased glutamate uptake. These data indicate that cAMP/protein kinase A signaling serves as an intracellular regulator upstream to the activation of the PTEN/Nedd4-mediated ubiquitin-proteasome system activity that is critical for glutamate transporter turnover. Under an in vivo condition, chronic morphine exposure also induced posttranscriptional down-regulation of the glutamate transporter EAAC1, which was prevented by MG-132, and transcriptional up-regulation of PTEN and Nedd4 within the spinal cord dorsal horn. Thus, inhibition of the ubiquitin-proteasome-mediated glutamate transporter degradation may be an important mechanism for preventing glutamate overexcitation and may offer a new strategy for treating certain neurological disorders and improving opioid therapy in chronic pain management. PMID:18539596

  9. Modeling the processing of mineral iron during dust transport

    NASA Astrophysics Data System (ADS)

    Vogelsberg, Ulrike; Wolke, Ralf; Tilgner, Andreas; Tegen, Ina; Herrmann, Hartmut

    2014-05-01

    The Saharan desert and the Gobi desert are the main contributors to Aeolian desert dust, which is a major source of micronutrients to the remote ocean regions. Micronutrients, such as transition metals like iron or copper, are regarded essential for biological processes of different marine species. In this context recent studies have shown that soluble iron, since it is generally the most abundant transition metal in dust particles, has the ability to control marine productivity and thereby likely influence the CO2- budget. Nevertheless, the processing of desert dust leading to the release of soluble iron still lacks sufficient understanding since several factors control the solubilization process. Especially anthropogenic emissions are regarded to significantly add to the amount of soluble iron by acidification of dust particles or by the direct emission of soluble iron comprised, e.g. in coal fly ash. For the investigation of the dissolution process of iron that takes place during dust transportation the spectral air parcel model SPACCIM is used. A mechanism describing the precipitation and dissolution of mineral particles by heterogeneous surface reactions has been implemented. Trajectory properties were derived from COSMO-MUSCAT simulations or from re-analysis data by HYSPLIT. Differences in the chemical composition and the amount of anthropogenic and naturally emitted species on the North African continent and the highly industrialized region of South-East Asia have considerable impact on the acidification of the desert dust. Under this aspect, special cases of dust outbreaks of the Saharan desert and the Gobi desert are investigated and compared with focus on soluble iron produced.

  10. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  11. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  12. 29 CFR 788.11 - “Transporting [such] products to the mill, processing plant, railroad, or other transportation...

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... DIRECTLY RELATED TO REGULATIONS FORESTRY OR LOGGING OPERATIONS IN WHICH NOT MORE THAN EIGHT EMPLOYEES ARE... terminal.” The transportation or movement of logs or other forestry products to a “mill processing plant... other forestry products onto railroad cars or other transportation facilities for further shipment...

  13. Kinetic simulation of neutral particle transport in sputtering processes

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Gallian, Sara; Brinkmann, Ralf Peter; Mussenbrock, Thomas; Ries, Stefan; Bibinov, Nikita; Awakowicz, Peter

    2013-09-01

    For many physical vapor deposition applications using sputtering processes, knowledge about the detailed spatial and temporal evolution of the involved gas species is of great importance. Modeling of the involved gas dynamic and plasma processes is however challenging, because the operating pressure is typically below 1 Pa. In consequence, only kinetic descriptions are appropriate. In order to approach this problem, the dynamics of sputtered particle transport through a neutral gas background is simulated. For this study, a modified version of the three-dimensional Direct Simulation Monte Carlo (DSMC) code dsmcFoam is utilized. The impact of a transient sputtering wind is investigated in a generic reactor geometry, which may be used for dc Magnetron Sputtering (dcMS), High Power Impulse Magnetron Sputtering (HiPIMS), as well as sputtering in capacitively coupled discharges. In the present work a rarefaction of the background gas is observed. Moreover in pulsed mode the temporal dynamics of the rarefaction and subsequent recovery of the background gas is investigated. This work is supported by the German Research Foundation in the frame of TRR 87.

  14. Fluctuation driven active molecular transport in passive channel proteins

    NASA Astrophysics Data System (ADS)

    Kosztin, Ioan

    2006-03-01

    Living cells interact with their extracellular environment through the cell membrane, which acts as a protective permeability barrier for preserving the internal integrity of the cell. However, cell metabolism requires controlled molecular transport across the cell membrane, a function that is fulfilled by a wide variety of transmembrane proteins, acting as either passive or active transporters. In this talk it is argued that, contrary to the general belief, in active cell membranes passive and spatially asymmetric channel proteins can act as active transporters by consuming energy from nonequilibrium fluctuations fueled by cell metabolism. This assertion is demonstrated in the case of the E. coli aquaglyceroporin GlpF channel protein, whose high resolution crystal structure is manifestly asymmetric. By calculating the glycerol flux through GlpF within the framework of a stochastic model, it is found that, as a result of channel asymmetry, glycerol uptake driven by a concentration gradient is enhanced significantly in the presence of non-equilibrium fluctuations. Furthermore, the enhancement caused by a ratchet-like mechanism is larger for the outward, i.e., from the cytoplasm to the periplasm, flux than for the inward one, suggesting that the same non-equilibrium fluctuations also play an important role in protecting the interior of the cell against poisoning by excess uptake of glycerol. Preliminary data on water and sugar transport through aquaporin and maltoporin channels, respectively, are indicative of the universality of the proposed nonequilibrium-fluctuation-driven active transport mechanism. This work was supported by grants from the Univ. of Missouri Research Board, the Institute for Theoretical Sciences and the Department of Energy (DOE Contract W-7405-ENG-36), and the National Science Foundation (FIBR-0526854).

  15. Hydrologic processes controlling herbicide transport in a Missouri claypan watershed

    NASA Astrophysics Data System (ADS)

    Liu, F.; Lerch, R.; Baffaut, C.; Yang, J.; Sadler, J.

    2011-12-01

    Hydrologic processes controlling herbicide transport are still poorly understood for claypan watersheds in the US Midwest. The presence of a near-surface claypan, a restrictive soil layer of smectitic mineralogy, may play a critical role in controlling herbicide transport to stream water. Data from Goodwater Creek Experimental Watershed (GCEW) (area = 72.5 km2) in central Missouri indicate that atrazine concentrations in stream water peaked during spring storm events, but high concentrations persisted in the baseflow following these events for days to weeks. It is hypothesized that hydrologic pathways exert a major control on atrazine concentrations in stream water. The hypothesis is tested using a combination of a statistical hydrograph model developed by Washington University in Saint Louis using Darcy's law and the diffusion equation and orthogonal data such as electric conductivity (EC). The basin time constant, the single fitting parameter for the model, was approximately 600 minutes or 0.4 days for GCEW. This value is similar to those for other small, non-claypan watersheds in Missouri. Stream flows were simulated very well by the model during the rising limbs of hydrographs for GCEW. Unlike other Missouri watersheds without claypan soils, stream flows in this claypan watershed were always significantly over-predicted for the prolonged falling tails, indicating a possible strong evapotranspiration effect during baseflow. EC values in shallow subsurface water indeed became much higher during baseflow than during storm events, consistent with the evapotranspiration effect on shallow subsurface water. These results suggests that both hydrologic pathways and evapotranspiration exert a major control on stream water quality in Goodwater Creek Experimental Watershed.

  16. Application studies of RFID technology in the process of coal logistics transport

    NASA Astrophysics Data System (ADS)

    Qiao, Bingqin; Chang, Xiaoming; Hao, Meiyan; Kong, Dejin

    2012-04-01

    For quality control problems in coal transport, RFID technology has been proposed to be applied to coal transportation process. The whole process RFID traceability system from coal production to consumption has been designed and coal supply chain logistics tracking system integration platform has been built, to form the coal supply chain traceability and transport tracking system and providing more and more transparent tracking and monitoring of coal quality information for consumers of coal. Currently direct transport and combined transport are the main forms of coal transportation in China. The means of transport are cars, trains and ships. In the booming networking environment of RFID technology, the RFID technology will be applied to coal logistics and provide opportunity for the coal transportation tracking in the process transportation.

  17. The contribution of an overlooked transport process to a wetland's methane emissions

    NASA Astrophysics Data System (ADS)

    Poindexter, Cristina M.; Baldocchi, Dennis D.; Matthes, Jaclyn Hatala; Knox, Sara Helen; Variano, Evan A.

    2016-06-01

    Wetland methane transport processes affect what portion of methane produced in wetlands reaches the atmosphere. We model what has been perceived to be the least important of these transport processes: hydrodynamic transport of methane through wetland surface water and show that its contribution to total methane emissions from a temperate freshwater marsh is surprisingly large. In our 1 year study, hydrodynamic transport comprised more than half of nighttime methane fluxes and was driven primarily by water column thermal convection occurring overnight as the water surface cooled. Overall, hydrodynamic transport was responsible for 32% of annual methane emissions. Many methane models have overlooked this process, but our results show that wetland methane fluxes cannot always be accurately described using only other transport processes (plant-mediated transport and ebullition). Modifying models to include hydrodynamic transport and the mechanisms that drive it, particularly convection, could help improve predictions of future wetland methane emissions.

  18. The role of the soil-root interface for transport processes in soils.

    NASA Astrophysics Data System (ADS)

    Vanderborght, J.; Schröder, N.; Garre, S.; Javaux, M.; Haber-Pohlmeier, S.; Pohlmeier, A. J.; Vereecken, H.

    2011-12-01

    Transport processes in soils are known to be strongly influenced by soil heterogeneity, which leads to a spatially variable flow field. Also plants, which take up water from the root zone, have an important impact on the flow field and therefore on solute transport processes. In order to describe the impact of plant water uptake on the flow field, water flow in the soil-plant system has to be simulated in an integrated way. The simulation models R-SWMS and PARTRACE (Javaux et al., 2008) couple 3-D water flow in the soil with flow in a plant root network and simulate solute transport using particle tracking. Using this model, the impact of root architecture, plant solute uptake mechanisms: passive, active and solute exclusion, and plant transpiration rate, on the water flow field in the soil and on solute dispersion was simulated. Root water uptake induces small-scale variations in the water flow field which increases solute dispersion. For the case that solutes are not taken up by plant roots but excluded, the simulations suggest that part of the applied solute mass is immobilized at the soil-root interface. This immobilisation results in lower effluent concentrations than would be expected from simulations with a 1-D transport model. Tracer experiments at two different scales: the small column scale with a single plant in packed sand and the lysimeter scale with a set of plants in an undisturbed large soil monolith, were conducted to validate the simulation studies. At the small column scale, transport of a Gd tracer and the root network were imaged using MRI. At the lysimeter scale, transport of a salt tracer was monitored by measuring tracer concentrations in the effluent of the lysimeter. Javaux, M., T. Schröder, J. Vanderborght, and H. Vereecken. 2008. Use of a three-dimensional detailed modeling approach for predicting root water uptake. Vadose Zone J. 7:1079-1088.doi: 10.2136/vzj2007.0115.

  19. Cytoplasmic transport of ribosomal subunits microinjected into the Xenopus laevis oocyte nucleus: a generalized, facilitated process

    PubMed Central

    1990-01-01

    To study the biochemistry of ribonucleoprotein export from the nucleus, we characterized an in vivo assay in which the cytoplasmic appearance of radiolabeled ribosomal subunits was monitored after their microinjection into Xenopus oocyte nuclei. Denaturing gel electrophoresis and sucrose density gradient sedimentation demonstrated that injected subunits were transported intact. Consistent with the usual subcellular distribution of ribosomes, transport was unidirectional, as subunits injected into the cytoplasm did not enter the nucleus. Transport displayed properties characteristic of a facilitated, energy-dependent process; the rate of export was saturable and transport was completely inhibited either by lowering the temperature or by depleting nuclei of ATP; the effect of lowered temperature was completely reversible. Transport of injected subunits was likely a process associated with the nuclear pore complex, since export was also inhibited by prior or simultaneous injection of wheat germ agglutinin, a lectin known to inhibit active nuclear transport by binding to N-acetyl glucosamine-containing glycoproteins present in the NPC (Hart, G. W., R. S. Haltiwanger, G. D. Holt, and W. G. Kelly. 1989. Annu. Rev. Biochem. 58:841-874). Although GlcNAc modified proteins exist on both the nuclear and cytoplasmic sides of the nuclear pore complex, ribosomal subunit export was inhibited only when wheat germ agglutinin was injected into the nucleus. Finally, we found that ribosomal subunits from yeast and Escherichia coli were efficiently exported from Xenopus oocyte nuclei, suggesting that export of some RNP complexes may be directed by a collective biochemical property rather than by specific macromolecular primary sequences or structures. PMID:2211825

  20. Decision process involved in preparing the Shippingport reactor pressure vessel for transport

    SciTech Connect

    Murphie, W.E.

    1989-01-01

    The most significant part of the Shippingport Station Decommissioning Project was the one-piece removal and shipment of the reactor pressure vessel (RPV). Implicit in the RPV transport was the task of qualifying the RPV as a waste package acceptable for shipment. Soon after physical decommissioning began on September 1985, questions regarding the packaging certification and transport of the RPV from Shippingport, Pennsylvania to the US Department of Energy (DOE) Hanford Waste Burial Site necessitated reexamination of several planning assumptions. A complete reassessment of the regulatory requirements governing the RPV shipment resulted in a programmatic decision to obtain a type B(U) Certificate of Compliance and abandon the originally planned US Department of Transportation (DOT) low specific activity (LSA) shipment. The decision process resulting in this conclusion was extensive and involved many organizations and agencies. Incidental to this process, several subtle certification issues were identified that required resolution. Some of these issues involved the definition of LSA material for large packages; interpretation and compliance with DOE, DOT and US Nuclear Regulatory Commission (NRC) regulations for the transport of radioactive material; incorporation of the International Atomic Energy Agency (IAEA) regulations by the Panama Canal; and DOE policy requiring advance notification to states of radioactive waste shipments. 2 figs.

  1. CERT Resilience Management Model - Mail-Specific Process Areas: International Mail Transportation (Version 1.0)

    DTIC Science & Technology

    2014-08-01

    international mail is transported to destination processing facilities in accordance with standards. IMT:SG2.SP3 Transport Inbound International...Mail Inbound international mail is transported to destination processing facilities in accordance with standards. IMT:SG2.SP4 Process Inbound ...International Mail Inbound international mail is processed in accordance with standards. IMT:SG3 Manage Risks to International Mail During

  2. Modeling cytoskeletal traffic: an interplay between passive diffusion and active transport.

    PubMed

    Neri, Izaak; Kern, Norbert; Parmeggiani, Andrea

    2013-03-01

    We introduce the totally asymmetric simple exclusion process with Langmuir kinetics on a network as a microscopic model for active motor protein transport on the cytoskeleton, immersed in the diffusive cytoplasm. We discuss how the interplay between active transport along a network and infinite diffusion in a bulk reservoir leads to a heterogeneous matter distribution on various scales: we find three regimes for steady state transport, corresponding to the scale of the network, of individual segments, or local to sites. At low exchange rates strong density heterogeneities develop between different segments in the network. In this regime one has to consider the topological complexity of the whole network to describe transport. In contrast, at moderate exchange rates the transport through the network decouples, and the physics is determined by single segments and the local topology. At last, for very high exchange rates the homogeneous Langmuir process dominates the stationary state. We introduce effective rate diagrams for the network to identify these different regimes. Based on this method we develop an intuitive but generic picture of how the stationary state of excluded volume processes on complex networks can be understood in terms of the single-segment phase diagram.

  3. Convection in the Physical Vapor Transport Process. Part 2; Thermosolutal

    NASA Technical Reports Server (NTRS)

    Duval, Walter M. B.

    1994-01-01

    We consider the effect of an inert gas on the diffusive-convective physical vapor transport process. We investigate the case when the temperature gradient is stabilizing and the concentration gradient is destabilizing for a wide parametric range. When an inert gas is present, the thermal and solutal convection oppose each other. The solutal field is destabilizing while the thermal field and the advective-diffusive flux stabilize the flow field. When the pressure of the inert component is increased, the stabilizing effect of the advective-diffusive flux is decreased. The intensity of convection as well as the oscillatory transient time increases. Below, the critical Rayleigh number, the nonlinear dynamics of the flow field show an oscillatory approach to steady state. For parametric values in the neighborhood of the critical Rayleigh number, the flow field undergoes a chaotic transient which settles to a periodic state. The asymptotic state of the flow field shows that growth and amalgamation of cells yields an overturning motion which results in an asymmetric cellular structure. The low gravity environment yields the stabilizing advective-diffusive flow which results in uniform temperature and concentration gradients near the crystal interface.

  4. Transport processes and interfacial phenomena in an evaporating meniscus

    SciTech Connect

    Sujanani, M.; Wayner, P.C. Jr.

    1991-01-01

    When a liquid film wets a solid surface, a contact line region is formed where the vapor, liquid and solid phases are in close proximity. The film thickness in this region varies from about 10 {mu}m (Capillary Meniscus) to less than about 100 nm (Adsorbed film). In addition to being functions of temperature and pressure (as for a bulk phase), the thermodynamic properties (e.g., chemical potential) of these thin films depend on their shape (curvature) and thickness due to surface forces. The coupled transport processes and interfacial phenomena occurring in this microscopic region are also controlled by these surface forces. The objective of this paper is to report experimental data which complement earlier analytical models of this region. The experimental setup consists of a flat silicon plate partially immersed at a small angle, {theta}, in a pool of liquid. The plate is in a closed cell and a spreading liquid (1,1,2-Trichlorotrifluoro ethane), in equilibrium with its own vapor, forms a zero contact angle with the plate. The plate can be electrically heated at the upper end by supplying power to a thin, rectangular platinum heater which is painted on the backside of the silicon wafer. The meniscus thickness profile, which is related to the effective pressure in the liquid, was used as a probe for understanding the sensitivity of the meniscus to the non-equilibrium effects associated with evaporation/condensation mechanisms. 5 refs., 8 figs.

  5. Space Transportation System Liftoff Debris Mitigation Process Overview

    NASA Technical Reports Server (NTRS)

    Mitchell, Michael; Riley, Christopher

    2011-01-01

    Liftoff debris is a top risk to the Space Shuttle Vehicle. To manage the Liftoff debris risk, the Space Shuttle Program created a team with in the Propulsion Systems Engineering & Integration Office. The Shutt le Liftoff Debris Team harnesses the Systems Engineering process to i dentify, assess, mitigate, and communicate the Liftoff debris risk. T he Liftoff Debris Team leverages off the technical knowledge and expe rtise of engineering groups across multiple NASA centers to integrate total system solutions. These solutions connect the hardware and ana lyses to identify and characterize debris sources and zones contribut ing to the Liftoff debris risk. The solutions incorporate analyses sp anning: the definition and modeling of natural and induced environmen ts; material characterizations; statistical trending analyses, imager y based trajectory analyses; debris transport analyses, and risk asse ssments. The verification and validation of these analyses are bound by conservative assumptions and anchored by testing and flight data. The Liftoff debris risk mitigation is managed through vigilant collab orative work between the Liftoff Debris Team and Launch Pad Operation s personnel and through the management of requirements, interfaces, r isk documentation, configurations, and technical data. Furthermore, o n day of launch, decision analysis is used to apply the wealth of ana lyses to case specific identified risks. This presentation describes how the Liftoff Debris Team applies Systems Engineering in their proce sses to mitigate risk and improve the safety of the Space Shuttle Veh icle.

  6. [Effect of nitrates on active transport of iodine].

    PubMed

    Szökeová, E; Tajtáková, M; Mirossay, L; Mojzis, J; Langer, P; Marcinová, E; Petrovicová, J; Zemberová, E; Bodnár, J

    2001-11-01

    Active iodine transport into the thyrocyte is catalyzed by the transmembrane transport protein Na+/J- symport (NIS) Nitrates can expel iodine from the bond with this transport protein which was found not only in the thyrocyte membrane but also in the cell membrane of the gastric mucosa. The weight of the thyroid gland in mg was significantly greater even when calculated in relation to body weight in the NIT group of rats who were given for 6 days nitrate by gastric tube (100 mg/kg/day) as compared with controls (CON) 17.56 +/- 8.4, 0.07 +/- 0.03/12.10 +/- 9.57, 0.05 +/- 0.03, P < or = 0.01. A lower thyroid activity in per cent calculated per 1 mg of its weight (1.39 +/- 1.0/2.22 +/- 0.9, P < or = 0.01), a higher activity in blood before removal of the thyroid gland (8.54 +/- 4.09/5.45 +/- 2.78) and a lower one after removal of the thyroid gland (1.09 +/- 0.05/0.21 +/- 0.10) before oral administration of I131 in group NIT, suggests a negative effect of nitrates on active iodine transport not only at the level of the thyrocyte but also possible interaction with iodine at the level of the digestive tract. A significantly higher serum level of TT3 in group NIT (0.66 +/- 0.27/0.44 +/- 0.21, P < or = 0.01 regardless of the TSH serum level (2.31 +/- 1.83/2.64 +/- 1.52) and T4 (22.72 +/- 8.2/25 +/- 11.0) suggests a qualitative change in thyroid hormone production in favour of T3 caused even by short-term nitrate administration.

  7. The Asymmetric Active Coupler: Stable Nonlinear Supermodes and Directed Transport

    PubMed Central

    Kominis, Yannis; Bountis, Tassos; Flach, Sergej

    2016-01-01

    We consider the asymmetric active coupler (AAC) consisting of two coupled dissimilar waveguides with gain and loss. We show that under generic conditions, not restricted by parity-time symmetry, there exist finite-power, constant-intensity nonlinear supermodes (NS), resulting from the balance between gain, loss, nonlinearity, coupling and dissimilarity. The system is shown to possess non-reciprocal dynamics enabling directed power transport functionality. PMID:27640818

  8. 77 FR 71430 - New Agency Information Collection Activity Under OMB Review: Public Transportation Baseline...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-11-30

    ... SECURITY Transportation Security Administration New Agency Information Collection Activity Under OMB Review: Public Transportation Baseline Assessment for Security Enhancement (BASE) Program AGENCY: Transportation Security Administration, DHS. ACTION: 30-day notice. SUMMARY: This notice announces that the...

  9. Synaptic activation modifies microtubules underlying transport of postsynaptic cargo.

    PubMed

    Maas, Christoph; Belgardt, Dorthe; Lee, Han Kyu; Heisler, Frank F; Lappe-Siefke, Corinna; Magiera, Maria M; van Dijk, Juliette; Hausrat, Torben J; Janke, Carsten; Kneussel, Matthias

    2009-05-26

    Synaptic plasticity, the ability of synapses to change in strength, requires alterations in synaptic molecule compositions over time, and synapses undergo selective modifications on stimulation. Molecular motors operate in sorting/transport of neuronal proteins; however, the targeting mechanisms that guide and direct cargo delivery remain elusive. We addressed the impact of synaptic transmission on the regulation of intracellular microtubule (MT)-based transport. We show that increased neuronal activity, as induced through GlyR activity blockade, facilitates tubulin polyglutamylation, a posttranslational modification thought to represent a molecular traffic sign for transport. Also, GlyR activity blockade alters the binding of the MT-associated protein MAP2 to MTs. By using the kinesin (KIF5) and the postsynaptic protein gephyrin as models, we show that such changes of MT tracks are accompanied by reduced motor protein mobility and cargo delivery into neurites. Notably, the observed neurite targeting deficits are prevented on functional depletion or gene expression knockdown of neuronal polyglutamylase. Our data suggest a previously undescribed concept of synaptic transmission regulating MT-dependent cargo delivery.

  10. Simulation of reactive processes related to biodegradation in aquifers. 1. Structure of the three-dimensional reactive transport model

    NASA Astrophysics Data System (ADS)

    Schäfer, Dirk; Schäfer, Wolfgang; Kinzelbach, Wolfgang

    1998-05-01

    The reactive transport model TBC (transport, biochemistry, and chemistry) numerically solves the equations for reactive transport in three-dimensional saturated groundwater flow. A finite element approximation and a standard Galerkin method are used. Solute transport is coupled to microbially mediated organic carbon degradation. Microbial growth is assumed to follow Monod-type kinetics. Substrate consumption and release of metabolic products is coupled to microbial growth via yield coefficients and stoichiometric relations. Additionally, the effects of microbial activity on selected inorganic chemical species in the aquifer can be considered. TBC allows the user to specify a wide range of possible biochemical and chemical reactions in the input file. This makes TBC a powerful and flexible simulation tool. It was developed to simulate reactive processes related to in situ bioremediation, but further fields of application are laboratory column studies on redox processes coupled to organic carbon degradation, field cases of intrinsic biodegradation, and early diagenetic processes in sediments.

  11. Regulation of ion channels and transporters by AMP-activated kinase (AMPK)

    PubMed Central

    Lang, Florian; Föller, Michael

    2014-01-01

    The energy-sensing AMP-activated kinase AMPK ensures survival of energy-depleted cells by stimulating ATP production and limiting ATP utilization. Both energy production and energy consumption are profoundly influenced by transport processes across the cell membane including channels, carriers and pumps. Accordingly, AMPK is a powerful regulator of transport across the cell membrane. AMPK regulates diverse K+ channels, Na+ channels, Ca2+ release activated Ca2+ channels, Cl- channels, gap junctional channels, glucose carriers, Na+/H+-exchanger, monocarboxylate-, phosphate-, creatine-, amino acid-, peptide- and osmolyte-transporters, Na+/Ca2+-exchanger, H+-ATPase and Na+/K+-ATPase. AMPK activates ubiquitin ligase Nedd4–2, which labels several plasma membrane proteins for degradation. AMPK further regulates transport proteins by inhibition of Rab GTPase activating protein (GAP) TBC1D1. It stimulates phosphatidylinositol 3-phosphate 5-kinase PIKfyve and inhibits phosphatase and tensin homolog (PTEN) via glycogen synthase kinase 3β (GSK3β). Moreover, it stabilizes F-actin as well as downregulates transcription factor NF-κB. All those cellular effects serve to regulate transport proteins. PMID:24366036

  12. Deformational mass transport and invasive processes in soil evolution

    NASA Technical Reports Server (NTRS)

    Brimhall, George H.; Chadwick, Oliver A.; Lewis, Chris J.; Compston, William; Williams, Ian S.; Danti, Kathy J.; Dietrich, William E.; Power, Mary E.; Hendricks, David; Bratt, James

    1992-01-01

    Channels left in soil by decayed roots and burrowing animals allow organic and inorganic precipitates and detritus to move through soil from above, to depths at which the minuteness of pores restricts further passage. Consecutive translocation-and-root-growth phases stir the soil, constituting an invasive, dilatational process which generates cumulative strains. Below the depths thus affected, mineral dissolution by descending organic acids leads to internal collapse; this softened/condensed precursor horizon is then transformed into soil via biological activity that mixes and expands the evolving residuum through root and micropore-network invasion.

  13. Studies of thunderstorm transport processes with aircraft using tracer techniques

    SciTech Connect

    Detwiler, A.G.; Smith, P.L.; Stith, J.L.

    1996-10-01

    Instrumented aircraft can provide in situ measurements of winds and turbulence useful for studying transport and dispersion in clouds. Using inert artificial gases as tracers, and fast response analyzers on aircraft, time-resolved observations of transport and dispersion have been obtained. Examples are shown of these types of observations in and around cumulus and cumulonimbus clouds. 23 refs., 6 figs.

  14. A fully resolved active musculo-mechanical model for esophageal transport

    PubMed Central

    Kou, Wenjun; Bhalla, Amneet Pal Singh; Griffith, Boyce E.; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

    2015-01-01

    Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multilayered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, and the esophagus is modeled as an actively contracting, fiber-reinforced tube. Before considering the full model of the esophagus, however, we first consider a standard benchmark problem of flow past a cylinder. Next a simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Finally, three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall resulting from the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function. PMID:26190859

  15. A fully resolved active musculo-mechanical model for esophageal transport

    NASA Astrophysics Data System (ADS)

    Kou, Wenjun; Bhalla, Amneet Pal Singh; Griffith, Boyce E.; Pandolfino, John E.; Kahrilas, Peter J.; Patankar, Neelesh A.

    2015-10-01

    Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multi-layered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, and the esophagus is modeled as an actively contracting, fiber-reinforced tube. Before considering the full model of the esophagus, however, we first consider a standard benchmark problem of flow past a cylinder. Next a simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Finally, three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall resulting from the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function.

  16. A fully resolved active musculo-mechanical model for esophageal transport.

    PubMed

    Kou, Wenjun; Bhalla, Amneet Pal Singh; Griffith, Boyce E; Pandolfino, John E; Kahrilas, Peter J; Patankar, Neelesh A

    2015-10-01

    Esophageal transport is a physiological process that mechanically transports an ingested food bolus from the pharynx to the stomach via the esophagus, a multilayered muscular tube. This process involves interactions between the bolus, the esophagus, and the neurally coordinated activation of the esophageal muscles. In this work, we use an immersed boundary (IB) approach to simulate peristaltic transport in the esophagus. The bolus is treated as a viscous fluid that is actively transported by the muscular esophagus, and the esophagus is modeled as an actively contracting, fiber-reinforced tube. Before considering the full model of the esophagus, however, we first consider a standard benchmark problem of flow past a cylinder. Next a simplified version of our model is verified by comparison to an analytic solution to the tube dilation problem. Finally, three different complex models of the multi-layered esophagus, which differ in their activation patterns and the layouts of the mucosal layers, are extensively tested. To our knowledge, these simulations are the first of their kind to incorporate the bolus, the multi-layered esophagus tube, and muscle activation into an integrated model. Consistent with experimental observations, our simulations capture the pressure peak generated by the muscle activation pulse that travels along the bolus tail. These fully resolved simulations provide new insights into roles of the mucosal layers during bolus transport. In addition, the information on pressure and the kinematics of the esophageal wall resulting from the coordination of muscle activation is provided, which may help relate clinical data from manometry and ultrasound images to the underlying esophageal motor function.

  17. Laboratory studies of aeolian sediment transport processes on planetary surfaces

    NASA Astrophysics Data System (ADS)

    Rasmussen, Keld R.; Valance, Alexandre; Merrison, Jonathan

    2015-09-01

    , but not all, older or recent wind tunnel observations. Similarly some measurements performed with uniform sand samples having grain diameters of the order of 0.25-0.40 mm indicate that ripple spacing depends on friction velocity in a similar way as particle jump length. The observations are thus in agreement with a recent ripple model that link the typical jump length to ripple spacing. A possible explanation for contradictory observations in some experiments may be that long observation sequences are required in order to assure that equilibrium exists between ripple geometry and wind flow. Quantitative understanding of saltation characteristics on Mars still lacks important elements. Based upon image analysis and numerical predictions, aeolian ripples have been thought to consist of relatively large grains (diameter > 0.6 mm) and that saltation occurs at high wind speeds (> 26 m/s) involving trajectories that are significantly longer than those on Earth (by a factor of 10-100). However, this is not supported by recent observations from the surface of Mars, which shows that active ripples in their geometry and composition have characteristics compatible with those of terrestrial ripples (Sullivan et al., 2008). Also the highest average wind speeds on Mars have been measured to be < 20 m/s, with even turbulent gusts not exceeding 25 m/s. Electrification is seen as a dominant factor in the transport dynamics of dust on Mars, affecting the structure, adhesive properties and detachment/entrainment mechanisms specifically through the formation of aggregates (Merrison et al., 2012). Conversely for terrestrial conditions electric fields typically observed are not intense enough to significantly affect sand transport rates while little is known in the case of extra-terrestrial environments.

  18. Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

    NASA Astrophysics Data System (ADS)

    Annewandter, Robert

    2014-05-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced gas transport and subsequent soil gas sampling during On-Site inspections. Generally, gas transport has been widely studied with different numerical codes. However, gas transport of radioxenons and radioiodines in the post-detonation regime and their possible fractionation is still neglected in the open peer-reviewed literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the multiple isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radionuclides, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different mass diffusivities due to mass differences between the radionuclides. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures or highly conductive faults which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a so-called ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which is recognized by the oil industry as leading in Discrete Fracture-Matrix (DFM) simulations. It has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations, fracture propagation in fractured, porous media, and Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic differential equations by a complementary finite

  19. Active and passive calcium transport systems in plant cells. Progress report, May 1986--January 1991

    SciTech Connect

    Sze, H.

    1991-12-31

    The ability to change cytoplasmic Ca{sup 2+} levels ([Ca{sup 2+}]) by cells has made this cation a key regulator of many biological processes. Cytoplasmic [Ca{sup 2+}] is determined by the coordination of passive Ca{sup 2+} fluxes which increase cytosolic [Ca{sup 2+}] and active Ca{sup 2+} transport systems that lower cytosolic [Ca{sup 2+}]. The mechanisms by which plant cells achieve this is poorly understood. We have initially used isolated vesicles from the plasma membrane or organellar membranes to study Ca{sup 2+} transport systems in oat roots (a monocot) and carrot suspension cells (a dicot). The objectives of the proposal were to identify and characterize active (energy-dependent) and passive calcium transport systems that work together to regulate calcium levels in the cytoplasm of plant cells.

  20. Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter

    NASA Astrophysics Data System (ADS)

    Grossmann, Nina; Vakkasoglu, Ahmet S.; Hulpke, Sabine; Abele, Rupert; Gaudet, Rachelle; Tampé, Robert

    2014-11-01

    The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the conserved aspartate, which coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. Our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate.

  1. Hydrogen peroxide stimulates the active transport of serotonin into human platelets

    SciTech Connect

    Bosin, T.R. )

    1991-03-11

    The effect of hydrogen peroxide on the active transport of serotonin (5-HT) by human platelets was investigated. Platelets were exposed to either a single dose of H{sub 2}O{sub 2} or to H{sub 2}O{sub 2} generated by the glucose/glucose oxidase or xanthine/xanthine oxidase enzyme systems. H{sub 2}{sub 2} produced a rapid, dose-dependent and time-dependent increase in 5-HT transport which was maximal after a 2 min incubation and decreased with continued incubation. Catalase completely prevented H{sub 2}O{sub 2}-induced stimulation and fluoxetine totally blocked 5-HT uptake into stimulated platelets. The glucose/glucose oxidase and the xanthine/xanthine oxidase generating systems produced a similar response to that of H{sub 2}O{sub 2}. In the xanthine/xanthine oxidase system, superoxide dismutase failed to alter the stimulation, while catalase effectively prevented the response. The kinetics of 5-HT transport indicated that H{sub 2}O{sub 2} treatment did not alter the K{sub m} of 5-HT transport but significantly increased the maximal rate of 5-HT transport. These data demonstrated that exposure of human platelets to H{sub 2}O{sub 2} resulted in a stimulation of the active transport of 5-HT and suggested that H{sub 2}O{sub 2} may function to regulate this process.

  2. Differences in associations between active transportation and built environmental exposures when expressed using different components of individual activity spaces.

    PubMed

    van Heeswijck, Torbjorn; Paquet, Catherine; Kestens, Yan; Thierry, Benoit; Morency, Catherine; Daniel, Mark

    2015-05-01

    This study assessed relationships between built environmental exposures measured within components of individual activity spaces (i.e., travel origins, destinations and paths in-between), and use of active transportation in a metropolitan setting. Individuals (n=37,165) were categorised as using active or sedentary transportation based on travel survey data. Generalised Estimating Equations analysis was used to test relationships with active transportation. Strength and significance of relationships between exposures and active transportation varied for different components of the activity space. Associations were strongest when including travel paths in expression of the built environment. Land use mix and greenness were negatively related to active transportation.

  3. Solution processed metal oxide thin film hole transport layers for high performance organic solar cells

    DOEpatents

    Steirer, K. Xerxes; Berry, Joseph J.; Chesin, Jordan P.; Lloyd, Matthew T.; Widjonarko, Nicodemus Edwin; Miedaner, Alexander; Curtis, Calvin J.; Ginley, David S.; Olson, Dana C.

    2017-01-10

    A method for the application of solution processed metal oxide hole transport layers in organic photovoltaic devices and related organic electronics devices is disclosed. The metal oxide may be derived from a metal-organic precursor enabling solution processing of an amorphous, p-type metal oxide. An organic photovoltaic device having solution processed, metal oxide, thin-film hole transport layer.

  4. Hydrogeochemical processes controlling subsurface transport from an upper subcatchment of Walker Branch watershed during storm events. 1. Hydrologic transport processes

    NASA Astrophysics Data System (ADS)

    Wilson, G. V.; Jardine, P. M.; Luxmoore, R. J.; Zelazny, L. W.; Lietzke, D. A.; Todd, D. E.

    1991-03-01

    Concerns over the effects of acid rain have stimulated numerous hydrometric and geochemical studies on forested watersheds with an emphasis on stream water chemistry. However, integrated studies are seriously lacking, and inferences of soil hydrogeochemical processes from periodic stream water chemistry may be grossly misleading. A small forested subcatchment was intensively instrumented for hydrologic and chemical analyses to improve our understanding of the processes that control subsurface transport of solutes. The timing and volume of subsurface flows were found to be highly dependent upon soil hydromorphologic properties. Development of perched water tables was the predominate mechanism of subsurface flow through the lower layers during moderate to high flow events. Perching of water was insignificant during low flow events and only partially responsible for lateral flow through the upper soil layers during moderate events. The importance of nonequilibrium conditions during even low flow events was illustrated by the occurrence of saturated flow through unsaturated (matric potentials < - 2kPa soil. The initial subsurface flow response of a moderate and high flow event was predominately (> 70%) new water that bypassed the soil matrix. As flows continued the percentage of old water increased. Intermittent rainfall during the high flow event caused multiple peaks in subsurface flow with subtle increases in perching. These hydrograph peaks were associated with decreases in the percentage of old water. This suggests an increase in the portion of infiltrating water that bypasses soil matrix water via macropores causing increases in subsurface flows with limited growth of perched water tables. The persistence of perched water tables as flow decreased was consistently observed. Decreases in solute concentrations causing decreases in conductivity of pores was inferred as one mechanism for this.

  5. Processing activities for STS-91 continue in OPF Bay 2

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Processing activities for STS-91 continue in KSC's Orbiter Processing Facility Bay 2. Two Get Away Special (GAS) canisters are shown after their installation into Discovery's payload bay. At left is G-648, an Canadian Space Agency-sponsored study of manufactured organic thin film by the physical vapor transport method, and the can on the right contains commemorative flags to be flown during the mission. STS-91 is scheduled to launch aboard the Space Shuttle Discovery for the ninth and final docking with the Russian Space Station Mir from KSC's Launch Pad 39A on June 2 with a launch window opening around 6:04 p.m. EDT.

  6. Kinetic theory of transport processes in partially ionized reactive plasma, I: General transport equations

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-03-01

    In this paper we derive the set of general transport equations for multicomponent partially ionized reactive plasma in the presence of electric and magnetic fields taking into account the internal degrees of freedom and electronic excitation of plasma particles. Our starting point is a generalized Boltzmann equation with the collision integral in the Wang-Chang and Uhlenbeck form and a reactive collision integral. We obtain a set of conservation equations for such plasma and employ a linearized variant of Grad's moment method to derive the system of moment (or transport) equations for the plasma species nonequilibrium parameters. Full and reduced transport equations, resulting from the linearized system of moment equations, are presented, which can be used to obtain transport relations and expressions for transport coefficients of electrons and heavy plasma particles (molecules, atoms and ions) in partially ionized reactive plasma.

  7. Interfacial phenomena and microscale transport processes in evaporating ultrathin menisci

    NASA Astrophysics Data System (ADS)

    Panchamgam, Sashidhar S.

    The study of interfacial phenomena in the three-phase contact line region, where a liquid-vapor interface intersects a solid surface, is of importance to many equilibrium and non-equilibrium processes. However, lack of experimental data on microscale transport processes controlled by interfacial phenomena has restricted progress. This thesis includes a high resolution image analyzing technique, based on reflectivity measurements, that accurately measures the thickness, contact angle and curvature profiles of ultrathin films, drops and curved menisci. In particular, the technique was used to emphasize measurements for thicknesses, delta < 100 nm, while studying delta < 2.5 mum. Using the "reflectivity technique", we studied fluid flow and heat transfer in a wickless, miniature heat pipe, a device which will be a very effective passive heat exchanger in a microgravity environment. The heat pipe is based on the Vertical Constrained Vapor Bubble (VCVB) concept. The broad objective was to increase the efficiency of the miniature heat pipe by enhancing the liquid flow towards the hotter region. This was achieved by understanding and manipulating the wetting and spreading characteristics of the liquid on the solid surface. By using a binary mixture (98% pentane and 2% octane by volume) instead of either pure pentane or octane, we were able to achieve a significant increase in the microscale phase change heat transfer. The experimental work was supported by numerical studies to understand the physics of the system at microscopic scale. In addition, using the reflectivity technique, we enhanced our understanding of interfacial phenomena in the contact line region. Experiments included flow instabilities in HFE-7000 meniscus on quartz (System S1), the spreading of a pentane (System S2 and S3), octane (System S4) and binary mixture menisci (System S5) during evaporation. The main objectives of the work are to present a new experimental technique, new observations, new data

  8. 23 CFR 450.206 - Scope of the statewide transportation planning process.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 23 Highways 1 2014-04-01 2014-04-01 false Scope of the statewide transportation planning process. 450.206 Section 450.206 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Statewide Transportation Planning and Programming §...

  9. 23 CFR 450.206 - Scope of the statewide transportation planning process.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 23 Highways 1 2012-04-01 2012-04-01 false Scope of the statewide transportation planning process. 450.206 Section 450.206 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Statewide Transportation Planning and Programming §...

  10. 23 CFR 450.206 - Scope of the statewide transportation planning process.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 23 Highways 1 2011-04-01 2011-04-01 false Scope of the statewide transportation planning process. 450.206 Section 450.206 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Statewide Transportation Planning and Programming §...

  11. 23 CFR 450.206 - Scope of the statewide transportation planning process.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 23 Highways 1 2013-04-01 2013-04-01 false Scope of the statewide transportation planning process. 450.206 Section 450.206 Highways FEDERAL HIGHWAY ADMINISTRATION, DEPARTMENT OF TRANSPORTATION PLANNING AND RESEARCH PLANNING ASSISTANCE AND STANDARDS Statewide Transportation Planning and Programming §...

  12. 23 CFR Appendix A to Part 450 - Linking the Transportation Planning and NEPA Processes

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... transportation planning process but does not second-guess the content of transportation plans and programs... must be cited in the NEPA document and their contents briefly described, so that the reader understands... option, the NEPA analyses prepared for project development can be integrated with transportation...

  13. Thermodynamics of Irreversible Processes. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Levin, Michael; Gallucci, V. F.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module describes the application of irreversible thermodynamics to biology. It begins with…

  14. Serotonin transporter activity in platelets and canine aggression.

    PubMed

    Rosado, Belén; García-Belenguer, Sylvia; Palacio, Jorge; Chacón, Gema; Villegas, Ainara; Alcalde, Ana I

    2010-10-01

    Several studies have suggested an inhibitory action of the serotonergic system in the regulation of canine aggression, but the role of the serotonin (5-HT) transporter (5-HTT) has not been investigated. Platelet 5-HT uptake has been proposed as a peripheral marker of brain 5-HTT. The aim of the study was to investigate the relationship between platelet 5-HTT activity and canine aggression by measuring the rate of 5-HT uptake mediated by 5-HTT in platelets and serum concentrations of 5-HT in both aggressive (n=14) and non-aggressive dogs (n=17). Aggressive dogs showed significantly higher 5-HT uptake by 5-HTT in platelets and lower serum concentrations of 5-HT, compared with the control group. These results suggested an association between an alteration in the serotonergic system and canine aggression, possibly mediated by an increased 5-HT transport.

  15. Platelet Serotonin Transporter Function Predicts Default-Mode Network Activity

    PubMed Central

    Kasess, Christian H.; Meyer, Bernhard M.; Hofmaier, Tina; Diers, Kersten; Bartova, Lucie; Pail, Gerald; Huf, Wolfgang; Uzelac, Zeljko; Hartinger, Beate; Kalcher, Klaudius; Perkmann, Thomas; Haslacher, Helmuth; Meyer-Lindenberg, Andreas; Kasper, Siegfried; Freissmuth, Michael; Windischberger, Christian; Willeit, Matthäus; Lanzenberger, Rupert; Esterbauer, Harald; Brocke, Burkhard; Moser, Ewald; Sitte, Harald H.; Pezawas, Lukas

    2014-01-01

    Background The serotonin transporter (5-HTT) is abundantly expressed in humans by the serotonin transporter gene SLC6A4 and removes serotonin (5-HT) from extracellular space. A blood-brain relationship between platelet and synaptosomal 5-HT reuptake has been suggested, but it is unknown today, if platelet 5-HT uptake can predict neural activation of human brain networks that are known to be under serotonergic influence. Methods A functional magnetic resonance study was performed in 48 healthy subjects and maximal 5-HT uptake velocity (Vmax) was assessed in blood platelets. We used a mixed-effects multilevel analysis technique (MEMA) to test for linear relationships between whole-brain, blood-oxygen-level dependent (BOLD) activity and platelet Vmax. Results The present study demonstrates that increases in platelet Vmax significantly predict default-mode network (DMN) suppression in healthy subjects independent of genetic variation within SLC6A4. Furthermore, functional connectivity analyses indicate that platelet Vmax is related to global DMN activation and not intrinsic DMN connectivity. Conclusion This study provides evidence that platelet Vmax predicts global DMN activation changes in healthy subjects. Given previous reports on platelet-synaptosomal Vmax coupling, results further suggest an important role of neuronal 5-HT reuptake in DMN regulation. PMID:24667541

  16. Curcumin directly inhibits the transport activity of GLUT1.

    PubMed

    Gunnink, Leesha K; Alabi, Ola D; Kuiper, Benjamin D; Gunnink, Stephen M; Schuiteman, Sam J; Strohbehn, Lauren E; Hamilton, Kathryn E; Wrobel, Kathryn E; Louters, Larry L

    2016-06-01

    Curcumin, a major ingredient in turmeric, has a long history of medicinal applications in a wide array of maladies including treatment for diabetes and cancer. Seemingly counterintuitive to the documented hypoglycemic effects of curcumin, however, a recent report indicates that curcumin directly inhibits glucose uptake in adipocytes. The major glucose transporter in adipocytes is GLUT4. Therefore, this study investigates the effects of curcumin in cell lines where the major transporter is GLUT1. We report that curcumin has an immediate inhibitory effect on basal glucose uptake in L929 fibroblast cells with a maximum inhibition of 80% achieved at 75 μM curcumin. Curcumin also blocks activation of glucose uptake by azide, glucose deprivation, hydroxylamine, or phenylarsine oxide. Inhibition does not increase with exposure time and the inhibitory effects reverse within an hour. Inhibition does not appear to involve a reaction between curcumin and the thiol side chain of a cysteine residue since neither prior treatment of cells with iodoacetamide nor curcumin with cysteine alters curcumin's inhibitory effects. Curcumin is a mixed inhibitor reducing the Vmax of 2DG transport by about half with little effect on the Km. The inhibitory effects of curcumin are not additive to the effects of cytochalasin B and 75 μM curcumin actually reduces specific cytochalasin B binding by 80%. Taken together, the data suggest that curcumin binds directly to GLUT1 at a site that overlaps with the cytochalasin B binding site and thereby inhibits glucose transport. A direct inhibition of GLUT proteins in intestinal epithelial cells would likely reduce absorption of dietary glucose and contribute to a hypoglycemic effect of curcumin. Also, inhibition of GLUT1 activity might compromise cancer cells that overexpress GLUT1 and be another possible mechanism for the documented anticancer effects of curcumin.

  17. Chloride transport in functionally active phagosomes isolated from Human neutrophils

    PubMed Central

    Aiken, Martha L.; Painter, Richard G.; Zhou, Yun; Wang, Guoshun

    2012-01-01

    Chloride anion is critical for hypochlorous acid (HOCl) production and microbial killing in neutrophil phagosomes. However, the molecular mechanism by which this anion is transported to the organelle is poorly understood. In this report, membrane-enclosed and functionally active phagosomes were isolated from human neutrophils by using opsonized paramagnetic latex microspheres and a rapid magnetic separation method. The phagosomes recovered were highly enriched for specific protein markers associated with this organelle such as lysosomal-associated membrane protein-1, myeloperoxidase (MPO), lactoferrin, and NADPH oxidase. When FITC–dextran was included in the phagocytosis medium, the majority of the isolated phagosomes retained the fluorescent label after isolation, indicative of intact membrane structure. Flow cytometric measurement of acridine orange, a fluorescent pH indicator, in the purified phagosomes demonstrated that the organelle in its isolated state was capable of transporting protons to the phagosomal lumen via the vacuolar-type ATPase proton pump (V-ATPase). When NADPH was supplied, the isolated phagosomes constitutively oxidized dihydrorhodamine 123, indicating their ability to produce hydrogen peroxide. The preparations also showed a robust production of HOCl within the phagosomal lumen when assayed with the HOCl-specific fluorescent probe R19-S by flow cytometry. MPO-mediated iodination of the proteins covalently conjugated to the phagocytosed beads was quantitatively measured. Phagosomal uptake of iodide and protein iodination were significantly blocked by chloride channel inhibitors, including CFTRinh-172 and NPPB. Further experiments determined that the V-ATPase-driving proton flux into the isolated phagosomes required chloride cotransport, and the cAMP-activated CFTR chloride channel was a major contributor to the chloride transport. Taken together, the data suggest that the phagosomal preparation described herein retains ion transport

  18. Curcumin directly inhibits the transport activity of GLUT1

    PubMed Central

    Gunnink, Leesha K.; Alabi, Ola D.; Kuiper, Benjamin D.; Gunnink, Stephen M.; Schuiteman, Sam J.; Strohbehn, Lauren E.; Hamilton, Kathryn E.; Wrobel, Kathryn E.; Louters, Larry L.

    2016-01-01

    Curcumin, a major ingredient in turmeric, has a long history of medicinal applications in a wide array of maladies including treatment for diabetes and cancer. Seemingly counterintuitive to the documented hypoglycemic effects of curcumin, however, a recent report indicates that curcumin directly inhibits glucose uptake in adipocytes. The major glucose transporter in adipocytes is GLUT4. Therefore, this study investigates the effects of curcumin in cell lines where the major transporter is GLUT1. We report that curcumin has an immediate inhibitory effect on basal glucose uptake in L929 fibroblast cells with a maximum inhibition of 80% achieved at 75 μM curcumin. Curcumin also blocks activation of glucose uptake by azide, glucose deprivation, hydroxylamine, or phenylarsine oxide. Inhibition does not increase with exposure time and the inhibitory effects reverse within an hour. Inhibition does not appear to involve a reaction between curcumin and the thiol side chain of a cysteine residue since neither prior treatment of cells with iodoacetamide nor curcumin with cysteine alters curcumin’s inhibitory effects. Curcumin is a mixed inhibitor reducing the Vmax of 2DG transport by about half with little effect on the Km. The inhibitory effects of curcumin are not additive to the effects of cytochalasin B and 75 μM curcumin actually reduces specific cytochalasin B binding by 80%. Taken together, the data suggest that curcumin binds directly to GLUT1 at a site that overlaps with the cytochalasin B binding site and thereby inhibits glucose transport. A direct inhibition of GLUT proteins in intestinal epithelial cells would likely reduce absorption of dietary glucose and contribute to a hypoglycemic effect of curcumin. Also, inhibition of GLUT1 activity might compromise cancer cells that overexpress GLUT1 and be another possible mechanism for the documented anticancer effects of curcumin. PMID:27039889

  19. Evaluation of the physical activity biography: sport and transport.

    PubMed

    Rogen, Sandra; Hofmann, Peter; Bauernhofer, Thomas; Müller, Wolfram

    2014-05-01

    Beside the genetic disposition, physical activity (PA) is one of the major health factors and can play a large role in the prevention and therapy of many diseases (cardiovascular diseases, cancer, obesity-related diseases etc.). In contrast to the genetic disposition, PA can be deliberately influenced by lifestyle. Therefore, it is of high importance to assess PA patterns. In order to assess PA reliably and validly, a new questionnaire (Physical Activity Biography, PAB) was created. The PAB assesses recreational PA (sport and transport) and enables to distinguish between endurance intensity levels and considers strength and high speed activity patterns throughout life. This study aims to evaluate the PAB by means of item analysis, retest-reliability and validity (criteria were physical fitness assessed by the questionnaire FFB-mot and by exercise tests). 141 participants answered the PAB. For deriving retest-reliability, 81 participants completed the PAB after a retest-interval of one month again. 55 participated in exercise tests and answered the FFB-mot to determine construct validity. Retest-reliability (ICC) above 0.7 was found for most items. For the items assessing recent PA, the criteria of convergent and discriminant validity were given. Despite the complexity of the question under study, the results fulfilled the expectations concerning reliability and validity. The PAB enables to assess the amount of sport and locomotion a person has accomplished during different life time frames and, because of the protective effects of PA on various diseases, may become an important tool for risk assessment. Key pointsThe risk of chronic diseases depends largely on physical activity biography.A new questionnaire (PAB) assessing recent and lifetime physical activity was created.The PAB assesses physical activity during sports and transport.The results of the evaluation of the PAB fulfilled the expectations.The PAB enables to determine a person's amount of recreational

  20. Evaluation of the Physical Activity Biography: Sport and Transport

    PubMed Central

    Rogen, Sandra; Hofmann, Peter; Bauernhofer, Thomas; Müller, Wolfram

    2014-01-01

    Beside the genetic disposition, physical activity (PA) is one of the major health factors and can play a large role in the prevention and therapy of many diseases (cardiovascular diseases, cancer, obesity-related diseases etc.). In contrast to the genetic disposition, PA can be deliberately influenced by lifestyle. Therefore, it is of high importance to assess PA patterns. In order to assess PA reliably and validly, a new questionnaire (Physical Activity Biography, PAB) was created. The PAB assesses recreational PA (sport and transport) and enables to distinguish between endurance intensity levels and considers strength and high speed activity patterns throughout life. This study aims to evaluate the PAB by means of item analysis, retest-reliability and validity (criteria were physical fitness assessed by the questionnaire FFB-mot and by exercise tests). 141 participants answered the PAB. For deriving retest-reliability, 81 participants completed the PAB after a retest-interval of one month again. 55 participated in exercise tests and answered the FFB-mot to determine construct validity. Retest-reliability (ICC) above 0.7 was found for most items. For the items assessing recent PA, the criteria of convergent and discriminant validity were given. Despite the complexity of the question under study, the results fulfilled the expectations concerning reliability and validity. The PAB enables to assess the amount of sport and locomotion a person has accomplished during different life time frames and, because of the protective effects of PA on various diseases, may become an important tool for risk assessment. Key points The risk of chronic diseases depends largely on physical activity biography. A new questionnaire (PAB) assessing recent and lifetime physical activity was created. The PAB assesses physical activity during sports and transport. The results of the evaluation of the PAB fulfilled the expectations. The PAB enables to determine a person’s amount of

  1. Reactive Transport and Coupled THM Processes in Engineering Barrier Systems (EBS)

    SciTech Connect

    Steefel, Carl; Rutqvist, Jonny; Tsang, Chin-Fu; Liu, Hui-Hai; Sonnenthal, Eric; Houseworth, Jim; Birkholzer, Jens

    2010-08-31

    Geological repositories for disposal of high-level nuclear wastes generally rely on a multi-barrier system to isolate radioactive wastes from the biosphere. The multi-barrier system typically consists of a natural barrier system, including repository host rock and its surrounding subsurface environment, and an engineering barrier system (EBS). EBS represents the man-made, engineered materials placed within a repository, including the waste form, waste canisters, buffer materials, backfill and seals (OECD, 2003). EBS plays a significant role in the containment and long-term retardation of radionuclide release. EBS is involved in complex thermal, hydrogeological, mechanical, chemical and biological processes, such as heat release due to radionuclide decay, multiphase flow (including gas release due to canister corrosion), swelling of buffer materials, radionuclide diffusive transport, waste dissolution and chemical reactions. All these processes are related to each other. An in-depth understanding of these coupled processes is critical for the performance assessment (PA) for EBS and the entire repository. Within the EBS group of Used Fuel Disposition (UFD) Campaign, LBNL is currently focused on (1) thermal-hydraulic-mechanical-chemical (THMC) processes in buffer materials (bentonite) and (2) diffusive transport in EBS associated with clay host rock, with a long-term goal to develop a full understanding of (and needed modeling capabilities to simulate) impacts of coupled processes on radionuclide transport in different components of EBS, as well as the interaction between near-field host rock (e.g., clay) and EBS and how they effect radionuclide release. This final report documents the progress that LBNL has made in its focus areas. Specifically, Section 2 summarizes progress on literature review for THMC processes and reactive-diffusive radionuclide transport in bentonite. The literature review provides a picture of the state-of-the-art of the relevant research areas

  2. The bacterial flagellar protein export apparatus processively transports flagellar proteins even with extremely infrequent ATP hydrolysis.

    PubMed

    Minamino, Tohru; Morimoto, Yusuke V; Kinoshita, Miki; Aldridge, Phillip D; Namba, Keiichi

    2014-12-22

    For self-assembly of the bacterial flagellum, a specific protein export apparatus utilizes ATP and proton motive force (PMF) as the energy source to transport component proteins to the distal growing end. The export apparatus consists of a transmembrane PMF-driven export gate and a cytoplasmic ATPase complex composed of FliH, FliI and FliJ. The FliI(6)FliJ complex is structurally similar to the α(3)β(3)γ complex of F(O)F(1)-ATPase. FliJ allows the gate to efficiently utilize PMF to drive flagellar protein export but it remains unknown how. Here, we report the role of ATP hydrolysis by the FliI(6)FliJ complex. The export apparatus processively transported flagellar proteins to grow flagella even with extremely infrequent or no ATP hydrolysis by FliI mutation (E211D and E211Q, respectively). This indicates that the rate of ATP hydrolysis is not at all coupled with the export rate. Deletion of FliI residues 401 to 410 resulted in no flagellar formation although this FliI deletion mutant retained 40% of the ATPase activity, suggesting uncoupling between ATP hydrolysis and activation of the gate. We propose that infrequent ATP hydrolysis by the FliI6FliJ ring is sufficient for gate activation, allowing processive translocation of export substrates for efficient flagellar assembly.

  3. Dopamine Transporter Activity Is Modulated by α-Synuclein.

    PubMed

    Butler, Brittany; Saha, Kaustuv; Rana, Tanu; Becker, Jonas P; Sambo, Danielle; Davari, Paran; Goodwin, J Shawn; Khoshbouei, Habibeh

    2015-12-04

    The duration and strength of the dopaminergic signal are regulated by the dopamine transporter (DAT). Drug addiction and neurodegenerative and neuropsychiatric diseases have all been associated with altered DAT activity. The membrane localization and the activity of DAT are regulated by a number of intracellular proteins. α-Synuclein, a protein partner of DAT, is implicated in neurodegenerative disease and drug addiction. Little is known about the regulatory mechanisms of the interaction between DAT and α-synuclein, the cellular location of this interaction, and the functional consequences of this interaction on the basal, amphetamine-induced DAT-mediated dopamine efflux, and membrane microdomain distribution of the transporter. Here, we found that the majority of DAT·α-synuclein protein complexes are found at the plasma membrane of dopaminergic neurons or mammalian cells and that the amphetamine-mediated increase in DAT activity enhances the association of these proteins at the plasma membrane. Further examination of the interaction of DAT and α-synuclein revealed a transient interaction between these two proteins at the plasma membrane. Additionally, we found DAT-induced membrane depolarization enhances plasma membrane localization of α-synuclein, which in turn increases dopamine efflux and enhances DAT localization in cholesterol-rich membrane microdomains.

  4. Investigation of transport processes in a large urban estuary

    NASA Astrophysics Data System (ADS)

    Caplow, T.; Schlosser, P.; Ho, D. T.; Santella, N.

    2003-04-01

    The Hudson River drains an area of 35 000 km^2 and terminates in a complex of waterways surrounding New York City. These waterways support the largest metropolitan area and third busiest seaport in the U.S., absorbing a large flux of industrial contaminants and wastewater, as well as accidental spills of oil and chemicals. Traditional approaches to the study of transport processes in New York Harbor include fluorescent dyes, moored current profilers, and numerical models, but these methods are limited by low temporal and spatial resolution and/or uncertain accuracy, particularly with regard to mixing. In July 2001, sulfur hexafluoride (SF_6) was injected into the Hudson River estuary near Newburgh, NY, about 100 km upstream from New York City. The resulting tracer patch was surveyed by boat (average resolution: 400 m) with an automated measurement system. After 13 days, the tracer patch was more than 100 km long. Net advection (0.5 km d-1), longitudinal dispersion (70 ± 4 m^2 s-1) and gas transfer velocity (6.5 ± 0.5 cm h-1) were determined from the tracer data. Tidal motions dominated river flow, and considerable quantities of tracer propagated upstream from the injection site. In July 2002, SF_6 was injected in the inner harbor, a complex of estuarine channels adjacent to the city. The tracer was tracked for 11 days. Due to tidal mixing, the shorter of two channels (9 km and 20 km) that connect with the outer harbor was the dominant seaward pathway, despite subtidal circulation in the opposite direction. As a result of gas transfer and seaward flushing, tracer mass in the inner harbor declined quasi-exponentially with a loss term of 0.29 ± 0.03 day-1. The loss term due to flushing alone (0.13 ± 0.02 day-1) indicated a mean residence time for water and solutes in the inner harbor of 8 days (without gas transfer). Further projects, including an investigation of wastewater fate, are planned within the lower estuary.

  5. CFD Model of Water Droplet Transport for ISS Hygiene Activity

    NASA Technical Reports Server (NTRS)

    Son, Chang H.

    2011-01-01

    The goal of the study is to assess the impacts of free water propagation in the Waste and Hygiene Compartment (WHC). Free water can be generated inside the WHC in small quantities due to crew hygiene activity. To mitigate potential impact of free water in Node 3 cabin the WHC doorway is enclosed by a waterproof bump-out, Kabin, with openings at the top and bottom. At the overhead side of the rack, there is a screen that prevents large drops of water from exiting. However, as the avionics fan in the WHC causes airflow toward the deck side of the rack, small quantities of free water may exit at the bottom of the Kabin. A Computational Fluid Dynamics (CFD) analysis of Node 3 cabin airflow made possible to identify the paths of water transport. The Node 3 airflow was computed for several ventilation scenarios. To simulate the droplet transport the Lagrangian discrete phase approach was used. Various initial droplet distributions were considered in the study. The droplet diameter was varied in the range of 2-20 mm. The results of the computations showed that most of the drops fall to the rack surface not far from the WHC curtain. The probability of the droplet transport to the adjacent rack surface with electronic equipment was predicted.

  6. Pentagalloylglucose Blocks the Nuclear Transport and the Process of Nucleocapsid Egress to Inhibit HSV-1 Infection.

    PubMed

    Jin, Fujun; Ma, Kaiqi; Chen, Maoyun; Zou, Muping; Wu, Yanting; Li, Feng; Wang, Yifei

    2016-01-01

    Herpes simplex virus type 1 (HSV-1), a widespread virus, causes a variety of human viral diseases worldwide. The serious threat of drug-resistance highlights the extreme urgency to develop novel antiviral drugs with different mechanisms of action. Pentagalloylglucose (PGG) is a natural polyphenolic compound with significant anti-HSV activity; however, the mechanisms underlying its antiviral activity need to be defined by further studies. In this study, we found that PGG treatment delays the nuclear transport process of HSV-1 particles by inhibiting the upregulation of dynein (a cellular major motor protein) induced by HSV-1 infection. Furthermore, PGG treatment affects the nucleocapsid egress of HSV-1 by inhibiting the expression and disrupting the cellular localization of pEGFP-UL31 and pEGFP-UL34, which are indispensable for HSV-1 nucleocapsid egress from the nucleus. However, the over-expression of pEGFP-UL31 and pEGFP-UL34 could decrease the antiviral effect of PGG. In this study, for the first time, the antiviral activity of PGG against acyclovir-resistant virus was demonstrated in vitro, and the possible mechanisms of its anti-HSV activities were identified based on the inhibition of nuclear transport and nucleocapsid egress in HSV-1. It was further confirmed that PGG could be a promising candidate for HSV therapy, especially for drug-resistant strains.

  7. Monsoon-related transport processes: HCFC-22 as a tracer for East-Asian pollution transport

    NASA Astrophysics Data System (ADS)

    Stiller, Gabriele; von Clarmann, Thomas; Kellmann, Sylvia; Chirkov, Maksym; Vogel, Bärbel; Müller, Rolf

    2016-04-01

    East-Asian pollution from Southern China or India was shown to be uplifted effectively by the Asian monsoon system to levels just below the tropopause. HCFC-22 nowadays has it strongest source region within East Asia. Due to its long lifetime in the troposphere, it is a very well suited transport tracer. We compare observations from MIPAS/Envisat of HCFC-22 with results from pollution transport modelling by the Lagrangian chemistry-transport model CLaMS. We find that East Asian pollution (and HCFC-22) is uplifted into the Asian monsoon anticyclone at the Eastern flank of the monsoon system. However, we do not find any indication of a significant transport through the tropopause of the Asian monsoon anticyclone into the stratosphere. In contrast, HCFC-22 is transported southwards into the tropics during the end phase and the break-down of the Asian monsoon anticyclone and distributed zonally in the tropics. By this a maximum layer of HCFC-22 just below the tropical tropopause is formed. Further transport into the stratosphere happens mainly by uplift within the upwelling branch of the Brewer-Dobson circulation.

  8. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... Transit Laws § 93.107 Relationship of transportation plan and TIP conformity with the NEPA process. The... quality modeling do not preclude the consideration of alternatives in the NEPA process or other...

  9. Modeling preferential water flow and solute transport in unsaturated soil using the active region model

    SciTech Connect

    Sheng, F.; Wang, K.; Zhang, R.; Liu, H.H.

    2009-03-15

    Preferential flow and solute transport are common processes in the unsaturated soil, in which distributions of soil water content and solute concentrations are often characterized as fractal patterns. An active region model (ARM) was recently proposed to describe the preferential flow and transport patterns. In this study, ARM governing equations were derived to model the preferential soil water flow and solute transport processes. To evaluate the ARM equations, dye infiltration experiments were conducted, in which distributions of soil water content and Cl{sup -} concentration were measured. Predicted results using the ARM and the mobile-immobile region model (MIM) were compared with the measured distributions of soil water content and Cl{sup -} concentration. Although both the ARM and the MIM are two-region models, they are fundamental different in terms of treatments of the flow region. The models were evaluated based on the modeling efficiency (ME). The MIM provided relatively poor prediction results of the preferential flow and transport with negative ME values or positive ME values less than 0.4. On the contrary, predicted distributions of soil water content and Cl- concentration using the ARM agreed reasonably well with the experimental data with ME values higher than 0.8. The results indicated that the ARM successfully captured the macroscopic behavior of preferential flow and solute transport in the unsaturated soil.

  10. Trailers transporting oranges to processing plants move Asian citrus psyllids

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Huanglongbing (citrus greening) is one of the most serious of citrus diseases. Movement of the disease occurs as a result of natural vector-borne infection and by movement of plant material. We demonstrate here that Diaphorina citri Kuwayama (vector of citrus greening pathogens) can be transported i...

  11. Modeling field scale unsaturated flow and transport processes

    SciTech Connect

    Gelhar, L.W.; Celia, M.A.; McLaughlin, D.

    1994-08-01

    The scales of concern in subsurface transport of contaminants from low-level radioactive waste disposal facilities are in the range of 1 to 1,000 m. Natural geologic materials generally show very substantial spatial variability in hydraulic properties over this range of scales. Such heterogeneity can significantly influence the migration of contaminants. It is also envisioned that complex earth structures will be constructed to isolate the waste and minimize infiltration of water into the facility. The flow of water and gases through such facilities must also be a concern. A stochastic theory describing unsaturated flow and contamination transport in naturally heterogeneous soils has been enhanced by adopting a more realistic characterization of soil variability. The enhanced theory is used to predict field-scale effective properties and variances of tension and moisture content. Applications illustrate the important effects of small-scale heterogeneity on large-scale anisotropy and hysteresis and demonstrate the feasibility of simulating two-dimensional flow systems at time and space scales of interest in radioactive waste disposal investigations. Numerical algorithms for predicting field scale unsaturated flow and contaminant transport have been improved by requiring them to respect fundamental physical principles such as mass conservation. These algorithms are able to provide realistic simulations of systems with very dry initial conditions and high degrees of heterogeneity. Numerical simulation of the movement of water and air in unsaturated soils has demonstrated the importance of air pathways for contaminant transport. The stochastic flow and transport theory has been used to develop a systematic approach to performance assessment and site characterization. Hypothesis-testing techniques have been used to determine whether model predictions are consistent with observed data.

  12. Additive effects of serotonin transporter and tryptophan hydroxylase-2 gene variation on emotional processing.

    PubMed

    Herrmann, Martin J; Huter, Theresa; Müller, Frauke; Mühlberger, Andreas; Pauli, Paul; Reif, Andreas; Renner, Tobias; Canli, Turhan; Fallgatter, Andreas J; Lesch, Klaus-Peter

    2007-05-01

    Prior studies reported that functional variants of both the serotonin transporter (5-HTT) and tryptophan hydroxylase-2 genes (TPH2), 2 key regulators of the serotonergic signaling pathway, modulate amygdala activation during emotional processing. We addressed the question whether these 2 gene variants modulate each other, using an emotional picture-processing task. Specifically, we measured event-related potentials (ERPs) during a passive emotional picture perception task, focusing on ERPs for the early posterior negativity (EPN) around 240 ms and for the slow wave starting at 315 ms. We found evidence for increased neural activity at 240 ms in individuals who carried 1 or 2 copies of the low-expression short variant of the 5-HTT. Carriers of T variant of the TPH2 also showed a tendency toward increased neural activity at 240 ms. Moreover, we observed an additive effect of both genotypes for EPN, with highest neural activity to emotional stimuli in individuals carrying combination of both short variant of 5-HTT and T variant of TPH2. Our results indicate that both the 5-HTT and the TPH2 genotypes modulate the sensory encoding of affective stimuli during early steps of visual processing and reveal additive effects of 2 genes in the serotonergic control of emotion regulation.

  13. Adult Active Transport in the Netherlands: An Analysis of Its Contribution to Physical Activity Requirements

    PubMed Central

    Fishman, Elliot; Böcker, Lars; Helbich, Marco

    2015-01-01

    Introduction Modern, urban lifestyles have engineered physical activity out of everyday life and this presents a major threat to human health. The Netherlands is a world leader in active travel, particularly cycling, but little research has sought to quantify the cumulative amount of physical activity through everyday walking and cycling. Methods Using data collected as part of the Dutch National Travel Survey (2010 – 2012), this paper determines the degree to which Dutch walking and cycling contributes to meeting minimum level of physical activity of 150 minutes of moderate intensity aerobic activity throughout the week. The sample includes 74,465 individuals who recorded at least some travel on the day surveyed. As physical activity benefits are cumulative, all walking and cycling trips are analysed, including those to and from public transport. These trips are then converted into an established measure of physical activity intensity, known as metabolic equivalents of tasks. Multivariate Tobit regression models were performed on a range of socio-demographic, transport resources, urban form and meteorological characteristics. Results The results reveal that Dutch men and women participate in 24 and 28 minutes of daily physical activity through walking and cycling, which is 41% and 55% more than the minimum recommended level. It should be noted however that some 57% of the entire sample failed to record any walking or cycling, and an investigation of this particular group serves as an important topic of future research. Active transport was positively related with age, income, bicycle ownership, urban density and air temperature. Car ownership had a strong negative relationship with physically active travel. Conclusion The results of this analysis demonstrate the significance of active transport to counter the emerging issue of sedentary lifestyle disease. The Dutch experience provides other countries with a highly relevant case study in the creation of

  14. Active migration and passive transport of malaria parasites.

    PubMed

    Douglas, Ross G; Amino, Rogerio; Sinnis, Photini; Frischknecht, Freddy

    2015-08-01

    Malaria parasites undergo a complex life cycle between their hosts and vectors. During this cycle the parasites invade different types of cells, migrate across barriers, and transfer from one host to another. Recent literature hints at a misunderstanding of the difference between active, parasite-driven migration and passive, circulation-driven movement of the parasite or parasite-infected cells in the various bodily fluids of mosquito and mammalian hosts. Because both active migration and passive transport could be targeted in different ways to interfere with the parasite, a distinction between the two ways the parasite uses to get from one location to another is essential. We discuss the two types of motion needed for parasite dissemination and elaborate on how they could be targeted by future vaccines or drugs.

  15. Directed transport of active particles over asymmetric energy barriers.

    PubMed

    Koumakis, N; Maggi, C; Di Leonardo, R

    2014-08-21

    We theoretically and numerically investigate the transport of active colloids to target regions, delimited by asymmetric energy barriers. We show that it is possible to introduce a generalized effective temperature that is related to the local variance of particle velocities. The stationary probability distributions can be derived from a simple diffusion equation in the presence of an inhomogeneous effective temperature resulting from the action of external force fields. In particular, transition rates over asymmetric energy barriers can be unbalanced by having different effective temperatures over the two slopes of the barrier. By varying the type of active noise, we find that equal values of diffusivity and persistence time may produce strongly varied effective temperatures and thus stationary distributions.

  16. Coupled ATPase-adenylate kinase activity in ABC transporters

    PubMed Central

    Kaur, Hundeep; Lakatos-Karoly, Andrea; Vogel, Ramona; Nöll, Anne; Tampé, Robert; Glaubitz, Clemens

    2016-01-01

    ATP-binding cassette (ABC) transporters, a superfamily of integral membrane proteins, catalyse the translocation of substrates across the cellular membrane by ATP hydrolysis. Here we demonstrate by nucleotide turnover and binding studies based on 31P solid-state NMR spectroscopy that the ABC exporter and lipid A flippase MsbA can couple ATP hydrolysis to an adenylate kinase activity, where ADP is converted into AMP and ATP. Single-point mutations reveal that both ATPase and adenylate kinase mechanisms are associated with the same conserved motifs of the nucleotide-binding domain. Based on these results, we propose a model for the coupled ATPase-adenylate kinase mechanism, involving the canonical and an additional nucleotide-binding site. We extend these findings to other prokaryotic ABC exporters, namely LmrA and TmrAB, suggesting that the coupled activities are a general feature of ABC exporters. PMID:28004795

  17. Active Transport of Nanomaterials Using Motor Proteins -Final Report

    SciTech Connect

    Hess, Henry

    2005-09-01

    During the six months of funding we have focused first on the completion of the research begun at the University of Washington in the previous funding cycle. Specifically, we developed a method to polymerize oriented networks of microtubules on lithographically patterned surfaces (M.S. thesis Robert Doot). The properties of active transport have been studied detail, yielding insights into the dispersion mechanisms (Nitta et al.). The assembly of multifunctional structures with a microtubule core has been investigated (Ramachandran et al.). Isaac Luria (B.S. in physics, U. of Florida 2005) worked on the directed assembly of nanoscale, non-equilibrium structures as a summer intern. He is now a graduate student in my group at the University of Florida. T. Nitta and H. Hess: Dispersion in Active Transport by Kinesin-Powered Molecular Shuttles, Nano Letters, 5, 1337-1342 (2005) S. Ramachandran, K.-H. Ernst, G. D. Bachand, V. Vogel, H. Hess*: Selective Loading of Kinesin-Powered Molecular Shuttles with Protein Cargo and its Application to Biosensing, submitted to Small (2005)

  18. Socioeconomic and regional differences in active transportation in Brazil

    PubMed Central

    de Sá, Thiago Hérick; Pereira, Rafael Henrique Moraes; Duran, Ana Clara; Monteiro, Carlos Augusto

    2016-01-01

    ABSTRACT OBJECTIVE To present national estimates regarding walking or cycling for commuting in Brazil and in 10 metropolitan regions. METHODS By using data from the Health section of 2008’s Pesquisa Nacional por Amostra de Domicílio (Brazil’s National Household Sample Survey), we estimated how often employed people walk or cycle to work, disaggregating our results by sex, age range, education level, household monthly income per capita, urban or rural address, metropolitan regions, and macro-regions in Brazil. Furthermore, we estimated the distribution of this same frequency according to quintiles of household monthly income per capita in each metropolitan region of the country. RESULTS A third of the employed men and women walk or cycle from home to work in Brazil. For both sexes, this share decreases as income and education levels rise, and it is higher among younger individuals, especially among those living in rural areas and in the Northeast region of the country. Depending on the metropolitan region, the practice of active transportation is two to five times more frequent among low-income individuals than among high-income individuals. CONCLUSIONS Walking or cycling to work in Brazil is most frequent among low-income individuals and the ones living in less economically developed areas. Active transportation evaluation in Brazil provides important information for public health and urban mobility policy-making PMID:27355465

  19. Benthic processes affecting contaminant transport in Upper Klamath Lake, Oregon

    USGS Publications Warehouse

    Kuwabara, James S.; Topping, Brent R.; Carter, James L.; Carlson, Rick A; Parchaso, Francis; Fend, Steven V.; Stauffer-Olsen, Natalie; Manning, Andrew J.; Land, Jennie M.

    2016-09-30

    Executive SummaryMultiple sampling trips during calendar years 2013 through 2015 were coordinated to provide measurements of interdependent benthic processes that potentially affect contaminant transport in Upper Klamath Lake (UKL), Oregon. The measurements were motivated by recognition that such internal processes (for example, solute benthic flux, bioturbation and solute efflux by benthic invertebrates, and physical groundwater-surface water interactions) were not integrated into existing management models for UKL. Up until 2013, all of the benthic-flux studies generally had been limited spatially to a number of sites in the northern part of UKL and limited temporally to 2–3 samplings per year. All of the benthic invertebrate studies also had been limited to the northern part of the lake; however, intensive temporal (weekly) studies had previously been completed independent of benthic-flux studies. Therefore, knowledge of both the spatial and temporal variability in benthic flux and benthic invertebrate distributions for the entire lake was lacking. To address these limitations, we completed a lakewide spatial study during 2013 and a coordinated temporal study with weekly sampling of benthic flux and benthic invertebrates during 2014. Field design of the spatially focused study in 2013 involved 21 sites sampled three times as the summer cyanobacterial bloom developed (that is, May 23, June 13, and July 3, 2013). Results of the 27-week, temporally focused study of one site in 2014 were summarized and partitioned into three periods (referred to herein as pre-bloom, bloom and post-bloom periods), each period involving 9 weeks of profiler deployments, water column and benthic sampling. Partitioning of the pre-bloom, bloom, and post-bloom periods were based on water-column chlorophyll concentrations and involved the following date intervals, respectively: April 15 through June 10, June 17 through August 13, and August 20 through October 16, 2014. To examine

  20. A fully resolved fluid-structure-muscle-activation model for esophageal transport

    NASA Astrophysics Data System (ADS)

    Kou, Wenjun; Bhalla, Amneet P. S.; Griffith, Boyce E.; Johnson, Mark; Patankar, Neelesh A.

    2013-11-01

    Esophageal transport is a mechanical and physiological process that transfers the ingested food bolus from the pharynx to the stomach through a multi-layered esophageal tube. The process involves interactions between the bolus, esophageal wall composed of mucosal, circular muscle (CM) and longitudinal muscle (LM) layers, and neurally coordinated muscle activation including CM contraction and LM shortening. In this work, we present a 3D fully-resolved model of esophageal transport based on the immersed boundary method. The model describes the bolus as a Newtonian fluid, the esophageal wall as a multi-layered elastic tube represented by springs and beams, and the muscle activation as a traveling wave of sequential actuation/relaxation of muscle fibers, represented by springs with dynamic rest lengths. Results on intraluminal pressure profile and bolus shape will be shown, which are qualitatively consistent with experimental observations. Effects of activating CM contraction only, LM shortening only or both, for the bolus transport, are studied. A comparison among them can help to identify the role of each type of muscle activation. The support of grant R01 DK56033 and R01 DK079902 from NIH is gratefully acknowledged.

  1. Examining Changes in Radioxenon Isotope Activity Ratios during Subsurface Transport

    NASA Astrophysics Data System (ADS)

    Annewandter, R.

    2013-12-01

    The Non-Proliferation Experiment (NPE) has demonstrated and modelled the usefulness of barometric pumping induced soil gas sampling during On-Site inspections. Gas transport has been widely studied with different numerical codes. However, gas transport of all radioxenons in the post-detonation regime and their possible fractionation is still neglected in the open literature. Atmospheric concentrations of the radioxenons Xe-135, Xe-133m, Xe-133 and Xe-131m can be used to discriminate between civilian releases (nuclear power plants or medical isotope facilities), and nuclear explosion sources. It is based on the isotopic activity ratio method. Yet it is not clear whether subsurface migration of the radioxenons, with eventual release into the atmosphere, can affect the activity ratios due to fractionation. Fractionation can be caused by different diffusivities due to mass differences between the radioxenons. A previous study showed surface arrival time of a chemically inert gaseous tracer is affected by its diffusivity. They observed detectable amount for SF6 50 days after detonation and 375 days for He-3. They predict 50 and 80 days for Xe-133 and Ar-37 respectively. Cyclical changes in atmospheric pressure can drive subsurface gas transport. This barometric pumping phenomenon causes an oscillatoric flow in upward trending fractures which, combined with diffusion into the porous matrix, leads to a net transport of gaseous components - a ratcheting effect. We use a general purpose reservoir simulator (Complex System Modelling Platform, CSMP++) which has been applied in a range of fields such as deep geothermal systems, three-phase black oil simulations , fracture propagation in fractured, porous media, Navier-Stokes pore-scale modelling among others. It is specifically designed to account for structurally complex geologic situation of fractured, porous media. Parabolic differential equations are solved by a continuous Galerkin finite-element method, hyperbolic

  2. Transport processes in partially saturate concrete: Testing and liquid properties

    NASA Astrophysics Data System (ADS)

    Villani, Chiara

    The measurement of transport properties of concrete is considered by many to have the potential to serve as a performance criterion that can be related to concrete durability. However, the sensitivity of transport tests to several parameters combined with the low permeability of concrete complicates the testing. Gas permeability and diffusivity test methods are attractive due to the ease of testing, their non-destructive nature and their potential to correlate to in-field carbonation of reinforced concrete structures. This work was aimed at investigating the potential of existing gas transport tests as a way to reliably quantify transport properties in concrete. In this study gas permeability and diffusivity test methods were analyzed comparing their performance in terms of repeatability and variability. The influence of several parameters was investigated such as moisture content, mixture proportions and gas flow. A closer look to the influence of pressure revealed an anomalous trend of permeability with respect to pressure. An alternative calculation is proposed in an effort to move towards the determination of intrinsic material properties that can serve as an input for service life prediction models. The impact of deicing salts exposure was also analyzed with respect to their alteration of the degree of saturation as this may affect gas transport in cementitious materials. Limited information were previously available on liquid properties over a wide range of concentrations. To overcome this limitation, this study quantified surface tension, viscosity in presence of deicing salts in a broad concentration range and at different temperatures. Existing models were applied to predict the change of fluid properties during drying. Vapor desorption isotherms were obtained to investigate the influence of deicing salts presence on the non-linear moisture diffusion coefficient. Semi-empirical models were used to quantify the initiation and the rate of drying using liquid

  3. Amphetamine activates calcium channels through dopamine transporter-mediated depolarization.

    PubMed

    Cameron, Krasnodara N; Solis, Ernesto; Ruchala, Iwona; De Felice, Louis J; Eltit, Jose M

    2015-11-01

    Amphetamine (AMPH) and its more potent enantiomer S(+)AMPH are psychostimulants used therapeutically to treat attention deficit hyperactivity disorder and have significant abuse liability. AMPH is a dopamine transporter (DAT) substrate that inhibits dopamine (DA) uptake and is implicated in DA release. Furthermore, AMPH activates ionic currents through DAT that modify cell excitability presumably by modulating voltage-gated channel activity. Indeed, several studies suggest that monoamine transporter-induced depolarization opens voltage-gated Ca(2+) channels (CaV), which would constitute an additional AMPH mechanism of action. In this study we co-express human DAT (hDAT) with Ca(2+) channels that have decreasing sensitivity to membrane depolarization (CaV1.3, CaV1.2 or CaV2.2). Although S(+)AMPH is more potent than DA in transport-competition assays and inward-current generation, at saturating concentrations both substrates indirectly activate voltage-gated L-type Ca(2+) channels (CaV1.3 and CaV1.2) but not the N-type Ca(2+) channel (CaV2.2). Furthermore, the potency to achieve hDAT-CaV electrical coupling is dominated by the substrate affinity on hDAT, with negligible influence of L-type channel voltage sensitivity. In contrast, the maximal coupling-strength (defined as Ca(2+) signal change per unit hDAT current) is influenced by CaV voltage sensitivity, which is greater in CaV1.3- than in CaV1.2-expressing cells. Moreover, relative to DA, S(+)AMPH showed greater coupling-strength at concentrations that induced relatively small hDAT-mediated currents. Therefore S(+)AMPH is not only more potent than DA at inducing hDAT-mediated L-type Ca(2+) channel currents but is a better depolarizing agent since it produces tighter electrical coupling between hDAT-mediated depolarization and L-type Ca(2+) channel activation.

  4. Transport dynamics of molecular motors that switch between an active and inactive state.

    PubMed

    Pinkoviezky, I; Gov, N S

    2013-08-01

    Molecular motors are involved in key transport processes in the cell. Many of these motors can switch from an active to a nonactive state, either spontaneously or depending on their interaction with other molecules. When active, the motors move processively along the filaments, while when inactive they are stationary. We treat here the simple case of spontaneously switching motors, between the active and inactive states, along an open linear track. We use our recent analogy with vehicular traffic, where we go beyond the mean-field description. We map the phase diagram of this system, and find that it clearly breaks the symmetry between the different phases, as compared to the standard total asymmetric exclusion process. We make several predictions that may be testable using molecular motors in vitro and in living cells.

  5. Electronic and Ionic Transport in Processable Conducting Polymers

    DTIC Science & Technology

    1991-04-12

    Reynolds, J. R. "Charge and Ion Transport in Poly(pyrrole copper phthalocyanine - sulfonate ) During Redox Switching," J. Electroanal. Chem., submitted...the following polymers: (1) copolymers of heterocyclic rings such as pyrrole or furan with disubstituted ( methyl or methoxy groups ) benzene; (2...SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIEL GRUP I SUB- GROUP IPoly[1,4-bis(2-furanyl)-2,5-disubstituted-p

  6. Simple jumping process with memory: Transport equation and diffusion

    NASA Astrophysics Data System (ADS)

    Kamińska, A.; Srokowski, T.

    2004-06-01

    We present a stochastic jumping process, defined in terms of jump-size probability density and jumping rate, which is a generalization of the well-known kangaroo process. The definition takes into account two process values: after and before the jump. Therefore, the process is able to preserve memory about its previous values. It possesses a simple stationary limit. Its master equation is interpreted as the kinetic equation with variable collision rate. The process can be easily applied to model systems which relax to distributions other than Maxwellian. The case of a constant jumping rate corresponds to the diffusion process, either normal or ballistic.

  7. Nicotine decreases the activity of glutamate transporter type 3.

    PubMed

    Yoon, Hea-Jo; Lim, Young-Jin; Zuo, Zhiyi; Hur, Wonseok; Do, Sang-Hwan

    2014-02-10

    Nicotine, the main ingredient of tobacco, elicits seizures in animal models and cigarette smoking is regarded as a behavioral risk factor associated with epilepsy or seizures. In the hippocampus, the origin of nicotine-induced seizures, most glutamate uptake could be performed primarily by excitatory amino acid transporter type 3 (EAAT3). An association between temporal lobe epilepsy and EAAT3 downregulation has been reported. Therefore, we hypothesized that nicotine may elicit seizures through the attenuation of EAAT3 activity. We investigated chronic nicotine exposure (72 h) cause reduction of the activity of EAAT3 in a Xenopus oocyte expression system using a two-electrode voltage clamp. The roles of protein kinase C (PKC) and phosphatidylinositol 3-kinase (PI3K) were also determined. Nicotine (0.001-1 μM) resulted in a time- and dose-dependent decrease in EAAT3 activity with maximal inhibition at nicotine concentrations of 0.03 μM or higher and at an exposure time of 72 h. Vmax on the glutamate response was significantly reduced in the nicotine group (0.03 μM for 72 h), but the Km value of EAAT3 for glutamate was not altered. When nicotine-exposed oocytes (0.03 μM for 72 h) were pretreated with phorbol-12-myristate-13-acetate (PMA, a PKC activator), the nicotine-induced reduction in EAAT3 activity was abolished. PKC inhibitors (staurosporine, chelerythrine, and calphostin C) significantly reduced basal EAAT3 activity, but there were no significant differences among the PKC inhibitors, nicotine, and PKC inhibitors+nicotine groups. Similar response patterns were observed among PI3K inhibitors (wortmannin and LY294002), nicotine, and PI3K inhibitors+nicotine. In conclusion, this study suggests that nicotine decreases EAAT3 activity, and that this inhibition seems to be dependent on PKC and PI3K. Our results may provide an additional mechanism for nicotine-induced seizure.

  8. Processing of Color Words Activates Color Representations

    ERIC Educational Resources Information Center

    Richter, Tobias; Zwaan, Rolf A.

    2009-01-01

    Two experiments were conducted to investigate whether color representations are routinely activated when color words are processed. Congruency effects of colors and color words were observed in both directions. Lexical decisions on color words were faster when preceding colors matched the color named by the word. Color-discrimination responses…

  9. Erosion Processes, Sediment Transport and Hydrological Responses Due to Land Use Changes in Serbian Ski Resorts

    NASA Astrophysics Data System (ADS)

    Ristic, R.; Radic, B.; Vasiljevic, N.; Nikic, Z.; Malusevic, I.

    2012-04-01

    The construction or improvement of Serbian ski resorts provoked intensive erosion processes, sediment transport and hydrological responses due to land use changes, affecting the surrounding environment and even endangering the functionality of the built objects. The dominant disturbing activities (clear cuttings, trunk transport, machine grading of slopes, huge excavations, and access road construction) were followed by the activities during skiing and non skiing periods (skiing, usage of snow groomers, moving of vehicles and tourists, forestry activities and overgrazing). These activities put a lot of pressure on the environment, including the removal or compaction of the surface soil layer, the reduction of the infiltration capacity, the destruction or degradation of the vegetation cover, the intensifying of the surface runoff and the development of erosion processes. The most affected ski runs were surveyed (scale 1:1000) and all damages were mapped and classified during the summers of 2007-2010. The development of rills and gullies was measured at experimental plots (100x60 m), and the survey data were entered into a GIS application. The area sediment yield and the intensity of erosion processes were estimated on the basis of the "Erosion Potential Method"(EPM). The changes in hydrological conditions were estimated by comparing the computed values of maximal discharges in the conditions before and after massive activities in the ski resorts, as well as by using the local hydrological records. The determination of maximal discharges was achieved using a combined method: the synthetic unit hydrograph (maximum ordinate of unit runoff, qmax) and the Soil Conservation Service (SCS, 1979) methodology (deriving effective rainfall, Pe, from total precipitation, Pb). The determination was performed for AMC III (Antecedent Moisture Conditions III: high water content in the soil and significantly reduced infiltration capacity). The computations of maximal discharges were

  10. Fatty acid transport and activation and the expression patterns of genes involved in fatty acid trafficking.

    PubMed

    Sandoval, Angel; Fraisl, Peter; Arias-Barrau, Elsa; Dirusso, Concetta C; Singer, Diane; Sealls, Whitney; Black, Paul N

    2008-09-15

    These studies defined the expression patterns of genes involved in fatty acid transport, activation and trafficking using quantitative PCR (qPCR) and established the kinetic constants of fatty acid transport in an effort to define whether vectorial acylation represents a common mechanism in different cell types (3T3-L1 fibroblasts and adipocytes, Caco-2 and HepG2 cells and three endothelial cell lines (b-END3, HAEC, and HMEC)). As expected, fatty acid transport protein (FATP)1 and long-chain acyl CoA synthetase (Acsl)1 were the predominant isoforms expressed in adipocytes consistent with their roles in the transport and activation of exogenous fatty acids destined for storage in the form of triglycerides. In cells involved in fatty acid processing including Caco-2 (intestinal-like) and HepG2 (liver-like), FATP2 was the predominant isoform. The patterns of Acsl expression were distinct between these two cell types with Acsl3 and Acsl5 being predominant in Caco-2 cells and Acsl4 in HepG2 cells. In the endothelial lines, FATP1 and FATP4 were the most highly expressed isoforms; the expression patterns for the different Acsl isoforms were highly variable between the different endothelial cell lines. The transport of the fluorescent long-chain fatty acid C(1)-BODIPY-C(12) in 3T3-L1 fibroblasts and 3T3-L1 adipocytes followed typical Michaelis-Menten kinetics; the apparent efficiency (k(cat)/K(T)) of this process increases over 2-fold (2.1 x 10(6)-4.5 x 10(6)s(-1)M(-1)) upon adipocyte differentiation. The V(max) values for fatty acid transport in Caco-2 and HepG2 cells were essentially the same, yet the efficiency was 55% higher in Caco-2 cells (2.3 x 10(6)s(-1)M(-1) versus 1.5 x 10(6)s(-1)M(-1)). The kinetic parameters for fatty acid transport in three endothelial cell types demonstrated they were the least efficient cell types for this process giving V(max) values that were nearly 4-fold lower than those defined form 3T3-L1 adipocytes, Caco-2 cells and HepG2 cells. The

  11. Active transport and obesity prevention - A transportation sector obesity impact scoping review and assessment for Melbourne, Australia.

    PubMed

    Brown, V; Moodie, M; Mantilla Herrera, A M; Veerman, J L; Carter, R

    2017-03-01

    Given the alarming prevalence of obesity worldwide and the need for interventions to halt the growing epidemic, more evidence on the role and impact of transport interventions for obesity prevention is required. This study conducts a scoping review of the current evidence of association between modes of transport (motor vehicle, walking, cycling and public transport) and obesity-related outcomes. Eleven reviews and thirty-three primary studies exploring associations between transport behaviours and obesity were identified. Cohort simulation Markov modelling was used to estimate the effects of body mass index (BMI) change on health outcomes and health care costs of diseases causally related to obesity in the Melbourne, Australia population. Results suggest that evidence for an obesity effect of transport behaviours is inconclusive (29% of published studies reported expected associations, 33% mixed associations), and any potential BMI effect is likely to be relatively small. Hypothetical scenario analyses suggest that active transport interventions may contribute small but significant obesity-related health benefits across populations (approximately 65 health adjusted life years gained per year). Therefore active transport interventions that are low cost and targeted to those most amenable to modal switch are the most likely to be effective and cost-effective from an obesity prevention perspective. The uncertain but potentially significant opportunity for health benefits warrants the collection of more and better quality evidence to fully understand the potential relationships between transport behaviours and obesity. Such evidence would contribute to the obesity prevention dialogue and inform policy across the transportation, health and environmental sectors.

  12. Thermally activated charge transport in microbial protein nanowires

    NASA Astrophysics Data System (ADS)

    Lampa-Pastirk, Sanela; Veazey, Joshua P.; Walsh, Kathleen A.; Feliciano, Gustavo T.; Steidl, Rebecca J.; Tessmer, Stuart H.; Reguera, Gemma

    2016-03-01

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors.

  13. Thermally activated charge transport in microbial protein nanowires.

    PubMed

    Lampa-Pastirk, Sanela; Veazey, Joshua P; Walsh, Kathleen A; Feliciano, Gustavo T; Steidl, Rebecca J; Tessmer, Stuart H; Reguera, Gemma

    2016-03-24

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors.

  14. Thermally activated charge transport in microbial protein nanowires

    PubMed Central

    Lampa-Pastirk, Sanela; Veazey, Joshua P.; Walsh, Kathleen A.; Feliciano, Gustavo T.; Steidl, Rebecca J.; Tessmer, Stuart H.; Reguera, Gemma

    2016-01-01

    The bacterium Geobacter sulfurreducens requires the expression of conductive protein filaments or pili to respire extracellular electron acceptors such as iron oxides and uranium and to wire electroactive biofilms, but the contribution of the protein fiber to charge transport has remained elusive. Here we demonstrate efficient long-range charge transport along individual pili purified free of metal and redox organic cofactors at rates high enough to satisfy the respiratory rates of the cell. Carrier characteristics were within the orders reported for organic semiconductors (mobility) and inorganic nanowires (concentration), and resistivity was within the lower ranges reported for moderately doped silicon nanowires. However, the pilus conductance and the carrier mobility decreased when one of the tyrosines of the predicted axial multistep hopping path was replaced with an alanine. Furthermore, low temperature scanning tunneling microscopy demonstrated the thermal dependence of the differential conductance at the low voltages that operate in biological systems. The results thus provide evidence for thermally activated multistep hopping as the mechanism that allows Geobacter pili to function as protein nanowires between the cell and extracellular electron acceptors. PMID:27009596

  15. Speech perception as an active cognitive process.

    PubMed

    Heald, Shannon L M; Nusbaum, Howard C

    2014-01-01

    One view of speech perception is that acoustic signals are transformed into representations for pattern matching to determine linguistic structure. This process can be taken as a statistical pattern-matching problem, assuming realtively stable linguistic categories are characterized by neural representations related to auditory properties of speech that can be compared to speech input. This kind of pattern matching can be termed a passive process which implies rigidity of processing with few demands on cognitive processing. An alternative view is that speech recognition, even in early stages, is an active process in which speech analysis is attentionally guided. Note that this does not mean consciously guided but that information-contingent changes in early auditory encoding can occur as a function of context and experience. Active processing assumes that attention, plasticity, and listening goals are important in considering how listeners cope with adverse circumstances that impair hearing by masking noise in the environment or hearing loss. Although theories of speech perception have begun to incorporate some active processing, they seldom treat early speech encoding as plastic and attentionally guided. Recent research has suggested that speech perception is the product of both feedforward and feedback interactions between a number of brain regions that include descending projections perhaps as far downstream as the cochlea. It is important to understand how the ambiguity of the speech signal and constraints of context dynamically determine cognitive resources recruited during perception including focused attention, learning, and working memory. Theories of speech perception need to go beyond the current corticocentric approach in order to account for the intrinsic dynamics of the auditory encoding of speech. In doing so, this may provide new insights into ways in which hearing disorders and loss may be treated either through augementation or therapy.

  16. MODELING COUPLED HYDROLOGICAL AND CHEMICAL PROCESSES: LONG-TERM URANIUM TRANSPORT FOLLOWING PHOSPHOROUS-FERTILIZATION

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contaminants in the vadose zone are affected by the physical processes of water flow, heat movement and multicomponent transport, as well as generally by a range of interacting biogeochemical processes. Coupling these various processes within one integrated numerical simulator provides a process-ba...

  17. Experimental thermal transport evolution of silane activated nano-clay reinforced styrene butadiene elastomeric nanocomposites

    NASA Astrophysics Data System (ADS)

    Iqbal, S. S.; Iqbal, N.; Jamil, T.; Bashir, A.; Shahid, M.

    2016-08-01

    In this study, silane activated nanoclay was reinforced in styrene butadiene rubber (SBR) to enhance the thermal resistance/stability and mechanical properties of SBR. silane activated nanoclay with variant concentrations was impregnated in the rubber matrix to fabricate polymer nanocomposites under control processing conditions. Experimental thermal transport, thermal oxidation, phase transition study, and mechanical properties of the nanocomposite specimens were carried out. Thermal insulation, thermal stability, and heat flow response were remarkably enhanced with the addition of nanokaolinite in the polymer matrix. Phase transition temperatures, their corresponding enthalpies, tensile strength, elastic modulus, elongation at break and hardness of the rubber composites were positively influenced with the filler incorporation into the host matrix. The Even dispersion of nanoreinforcements, morphological and compositional analyses of the thermal transport tested specimens were performed using scanning electron microscopy and energy dispersive spectroscopy, respectively.

  18. Recent Cooperative Research Activities of HDD and Flexible Media Transport Technologies in Japan

    NASA Astrophysics Data System (ADS)

    Ono, Kyosuke

    This paper presents the recent status of industry-university cooperative research activities in Japan on the mechatronics of information storage and input/output equipment. There are three research committees for promoting information exchange on technical problems and research topics of head-disk interface in hard disk drives (HDD), flexible media transport and image printing processes which are supported by the Japan Society of Mechanical Engineering (JSME), the Japanese Society of Tribologists (JAST) and the Japan Society of Precision Engineering (JSPE). For hard disk drive technology, the Storage Research Consortium (SRC) is supporting more than 40 research groups in various different universities to perform basic research for future HDD technology. The past and present statuses of these activities are introduced, particularly focusing on HDD and flexible media transport mechanisms.

  19. Theory of activated transport in bilayer quantum Hall systems.

    PubMed

    Roostaei, B; Mullen, K J; Fertig, H A; Simon, S H

    2008-07-25

    We analyze the transport properties of bilayer quantum Hall systems at total filling factor nu=1 in drag geometries as a function of interlayer bias, in the limit where the disorder is sufficiently strong to unbind meron-antimeron pairs, the charged topological defects of the system. We compute the typical energy barrier for these objects to cross incompressible regions within the disordered system using a Hartree-Fock approach, and show how this leads to multiple activation energies when the system is biased. We then demonstrate using a bosonic Chern-Simons theory that in drag geometries current in a single layer directly leads to forces on only two of the four types of merons, inducing dissipation only in the drive layer. Dissipation in the drag layer results from interactions among the merons, resulting in very different temperature dependences for the drag and drive layers, in qualitative agreement with experiment.

  20. Controlling contagion processes in activity driven networks.

    PubMed

    Liu, Suyu; Perra, Nicola; Karsai, Márton; Vespignani, Alessandro

    2014-03-21

    The vast majority of strategies aimed at controlling contagion processes on networks consider the connectivity pattern of the system either quenched or annealed. However, in the real world, many networks are highly dynamical and evolve, in time, concurrently with the contagion process. Here, we derive an analytical framework for the study of control strategies specifically devised for a class of time-varying networks, namely activity-driven networks. We develop a block variable mean-field approach that allows the derivation of the equations describing the coevolution of the contagion process and the network dynamic. We derive the critical immunization threshold and assess the effectiveness of three different control strategies. Finally, we validate the theoretical picture by simulating numerically the spreading process and control strategies in both synthetic networks and a large-scale, real-world, mobile telephone call data set.

  1. Hydrogen Transport to Mars Enables the Sabatier/Electrolysis Process

    NASA Technical Reports Server (NTRS)

    Mueller, P. J.; Rapp, D.

    1997-01-01

    The Sabatier/Electrolysis (S/E) process is an attractive approach to in situ propellant production (ISPP), and a breadboard demonstration of this process at Lockheed Martin Astronautics funded by JPL performed very well, with high conversion efficiency, and reliable diurnal operation. There is a net usage of hydrogen in the S/E process, and this has been the principal problem for this approach to ISPP.

  2. Multiple-tracer tests for contaminant transport process identification in saturated municipal solid waste

    SciTech Connect

    Woodman, N.D. Rees-White, T.C.; Stringfellow, A.M.; Beaven, R.P.; Hudson, A.P.

    2015-04-15

    Highlights: • Multiple tracers were applied to saturated MSW to test dual-porosity properties. • Lithium demonstrated to be non-conservative as a tracer. • 260 mm diameter column too small to test transport properties of MSW. • The classical advection-dispersion mode was rejected due to high dispersivity. • Characteristic diffusion times did not vary with the tracer. - Abstract: Two column tests were performed in conditions emulating vertical flow beneath the leachate table in a biologically active landfill to determine dominant transport mechanisms occurring in landfills. An improved understanding of contaminant transport process in wastes is required for developing better predictions about potential length of the long term aftercare of landfills, currently measured in timescales of centuries. Three tracers (lithium, bromide and deuterium) were used. Lithium did not behave conservatively. Given that lithium has been used extensively for tracing in landfill wastes, the tracer itself and the findings of previous tests which assume that it has behaved conservatively may need revisiting. The smaller column test could not be fitted with continuum models, probably because the volume of waste was below a representative elemental volume. Modelling compared advection-dispersion (AD), dual porosity (DP) and hybrid AD–DP models. Of these models, the DP model was found to be the most suitable. Although there is good evidence to suggest that diffusion is an important transport mechanism, the breakthrough curves of the different tracers did not differ from each other as would be predicted based on the free-water diffusion coefficients. This suggested that solute diffusion in wastes requires further study.

  3. Complement activation of electrogenic ion transport in isolated rat colon.

    PubMed

    McCole, D F; Otti, B; Newsholme, P; Baird, A W

    1997-11-15

    The complement cascade is an important component in many immune and inflammatory reactions and may contribute to both the diarrhoea and inflammation associated with inflammatory bowel disease. Isolated rat colonic mucosae were voltage clamped in Ussing chambers. Basolateral addition of zymosan-activated whole human serum (ZAS) induced a rapid onset, transient inward short circuit current (SCC). This response was concentration dependent and was significantly attenuated by pre-heating ZAS at 60 degrees C for 30 min. Depletion of complement from normal human serum with cobra venom factor (CVF) significantly lowered SCC responses. Chloride was the primary charge carrying ion as responses to ZAS were abolished in the presence of the loop diuretic bumetanide. The complement component C3a stimulated ion transport but not to the same extent as whole serum. Exogenous C5 was without effect. The cyclooxygenase inhibitor piroxicam significantly attenuated the response to ZAS. These findings support the possibility that complement activation may contribute to the pathophysiology of secretory diarrhoea since activation of electrogenic chloride secretion converts intestinal epithelia to a state of net fluid secretion.

  4. Serotonin transporter genotype modulates amygdala activity during mood regulation

    PubMed Central

    Rao, Hengyi; Wang, Jiongjiong; Detre, John A.; Breland, Jessica; Sankoorikal, Geena Mary V.; Brodkin, Edward S.; Farah, Martha J.

    2010-01-01

    Recent studies have implicated the short allele of the serotonin transporter-linked polymorphic region (5-HTTLPR) in depression vulnerability, particularly in the context of stress. Several neuroimaging studies have shown that 5-HTTLPR genotype predicts amygdala reactivity to negatively valenced stimuli, suggesting a mechanism whereby the short allele confers depression risk. The current study investigated whether 5-HTTLPR genotype similarly affects neural activity during an induced sad mood and during recovery from sad mood. Participants were 15 homozygous short (S) and 15 homozygous long (L) individuals. Regional cerebral blood flow was measured with perfusion functional magnetic resonance imaging during four scanning blocks: baseline, sad mood, mood recovery and following return to baseline. Comparing mood recovery to baseline, both whole brain analyses and template-based region-of-interest analyses revealed greater amygdala activity for the S vs the L-group. There were no significant amygdala differences found during the induced sad mood. These results demonstrate the effect of the S allele on amygdala activity during intentional mood regulation and suggest that amygdala hyperactivity during recovery from a sad mood may be one mechanism by which the S allele confers depression risk. PMID:19858108

  5. Association of serotonin transporter promoter regulatory region polymorphism and cerebral activity to visual presentation of food.

    PubMed

    Kaurijoki, Salla; Kuikka, Jyrki T; Niskanen, Eini; Carlson, Synnöve; Pietiläinen, Kirsi H; Pesonen, Ullamari; Kaprio, Jaakko M; Rissanen, Aila; Tiihonen, Jari; Karhunen, Leila

    2008-07-01

    Recent functional magnetic resonance imaging (fMRI) studies have revealed links between genetic polymorphisms and cognitive and behavioural processes. Serotonin is a classical neurotransmitter of central nervous system, and it is connected to the control of appetite and satiety. In this study, the relationship between the functional variation in the serotonin transporter gene and the activity in the left posterior cingulate cortex (PCC), a brain area activated by visual food stimuli was explored. Thirty subjects underwent serial fMRI studies and provided DNA for genetic analyses. Subjects homozygous for the long allele exhibited greater left PCC activity in the comparison food > non-food compared with individuals heterozygous or homozygous for the short allele. The association between genotype and activation was linear, the subjects with two copies of the long allele variant having the strongest activation. These results demonstrate the possible genetically driven variation in the response of the left PCC to visual presentation of food in humans.

  6. Physical Activity Energy Expenditure in Dutch Adolescents: Contribution of Active Transport to School, Physical Education, and Leisure Time Activities

    ERIC Educational Resources Information Center

    Slingerland, Menno; Borghouts, Lars B.; Hesselink, Matthijs K. C.

    2012-01-01

    Background: Detailed knowledge about physical activity energy expenditure (PAEE) can guide the development of school interventions aimed at reducing overweight in adolescents. However, relevant components of PAEE have never been objectively quantified in this population. This study investigated the contribution of active transport to and from…

  7. Localization of the calcium-regulated citrate transport process in proximal tubule cells.

    PubMed

    Hering-Smith, Kathleen S; Mao, Weibo; Schiro, Faith R; Coleman-Barnett, Joycelynn; Pajor, Ana M; Hamm, L Lee

    2014-06-01

    Urinary citrate is an important inhibitor of calcium-stone formation. Most of the citrate reabsorption in the proximal tubule is thought to occur via a dicarboxylate transporter NaDC1 located in the apical membrane. OK cells, an established opossum kidney proximal tubule cell line, transport citrate but the characteristics change with extracellular calcium such that low calcium solutions stimulate total citrate transport as well as increase the apparent affinity for transport. The present studies address several fundamental properties of this novel process: the polarity of the transport process, the location of the calcium-sensitivity and whether NaDC1 is present in OK cells. OK cells grown on permeable supports exhibited apical >basolateral citrate transport. Apical transport of both citrate and succinate was sensitive to extracellular calcium whereas basolateral transport was not. Apical calcium, rather than basolateral, was the predominant determinant of changes in transport. Also 2,3-dimethylsuccinate, previously identified as an inhibitor of basolateral dicarboxylate transport, inhibited apical citrate uptake. Although the calcium-sensitive transport process in OK cells is functionally not typical NaDC1, NaDC1 is present in OK cells by Western blot and PCR. By immunolocalization studies, NaDC1 was predominantly located in discrete apical membrane or subapical areas. However, by biotinylation, apical NaDC1 decreases in the apical membrane with lowering calcium. In sum, OK cells express a calcium-sensitive/regulated dicarboxylate process at the apical membrane which responds to variations in apical calcium. Despite the functional differences of this process compared to NaDC1, NaDC1 is present in these cells, but predominantly in subapical vesicles.

  8. Process for preparing active oxide powders

    DOEpatents

    Berard, Michael F.; Hunter, Jr., Orville; Shiers, Loren E.; Dole, Stephen L.; Scheidecker, Ralph W.

    1979-02-20

    An improved process for preparing active oxide powders in which cation hydroxide gels, prepared in the conventional manner are chemically dried by alternately washing the gels with a liquid organic compound having polar characteristics and a liquid organic compound having nonpolar characteristics until the mechanical water is removed from the gel. The water-free cation hydroxide is then contacted with a final liquid organic wash to remove the previous organic wash and speed drying. The dried hydroxide treated in the conventional manner will form a highly sinterable active oxide powder.

  9. Compromising KCC2 transporter activity enhances the development of continuous seizure activity

    PubMed Central

    Kelley, Matthew R.; Deeb, Tarek Z.; Brandon, Nicholas J.; Dunlop, John; Davies, Paul A.; Moss, Stephen J.

    2016-01-01

    Impaired neuronal inhibition has long been associated with the increased probability of seizure occurrence and heightened seizure severity. Fast synaptic inhibition in the brain is primarily mediated by the type A γ-aminobutyric acid receptors (GABAARs), ligand-gated ion channels that can mediate Cl− influx resulting in membrane hyperpolarization and the restriction of neuronal firing. In most adult brain neurons, the K+/Cl− co-transporter-2 (KCC2) establishes hyperpolarizing GABAergic inhibition by maintaining low [Cl−]i. In this study, we sought to understand how decreased KCC2 transport function affects seizure event severity. We impaired KCC2 transport in the 0-Mg2+ ACSF and 4-aminopyridine in vitro models of epileptiform activity in acute mouse brain slices. Experiments with the selective KCC2 inhibitor VU0463271 demonstrated that reduced KCC2 transport increased the duration of SLEs, resulting in non-terminating discharges of clonic-like activity. We also investigated slices obtained from the KCC2-Ser940Ala (S940A) point-mutant mouse, which has a mutation at a known functional phosphorylation site causing behavioral and cellular deficits under hyperexcitable conditions. We recorded from the entorhinal cortex of S940A mouse brain slices in both 0-Mg2+ ACSF and 4-aminopyridine, and demonstrated that loss of the S940 residue increased the susceptibility of continuous clonic-like discharges, an in vitro form of status epilepticus. Our experiments revealed KCC2 transport activity is a critical factor in seizure event duration and mechanisms of termination. Our results highlight the need for therapeutic strategies that potentiate KCC2 transport function in order to decrease seizure event severity and prevent the development of status epilepticus. PMID:27108931

  10. 23 CFR 450.320 - Congestion management process in transportation management areas.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... effective integrated management and operation of the multimodal transportation system, based on a... management process should result in multimodal system performance measures and strategies that can be... transportation system management and operations. Where the addition of general purpose lanes is determined to...

  11. 23 CFR 450.306 - Scope of the metropolitan transportation planning process.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    .... (e) In carrying out the metropolitan transportation planning process, MPOs, States, and public... CFR part 940. (g) Preparation of the coordinated public transit-human services transportation plan, as... urbanized area not designated as a TMA that is an air quality attainment area, the MPO(s) may propose...

  12. 23 CFR 450.306 - Scope of the metropolitan transportation planning process.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    .... (e) In carrying out the metropolitan transportation planning process, MPOs, States, and public... CFR part 940. (g) Preparation of the coordinated public transit-human services transportation plan, as... urbanized area not designated as a TMA that is an air quality attainment area, the MPO(s) may propose...

  13. Active voltammetric microsensors with neural signal processing.

    SciTech Connect

    Vogt, M. C.

    1998-12-11

    Many industrial and environmental processes, including bioremediation, would benefit from the feedback and control information provided by a local multi-analyte chemical sensor. For most processes, such a sensor would need to be rugged enough to be placed in situ for long-term remote monitoring, and inexpensive enough to be fielded in useful numbers. The multi-analyte capability is difficult to obtain from common passive sensors, but can be provided by an active device that produces a spectrum-type response. Such new active gas microsensor technology has been developed at Argonne National Laboratory. The technology couples an electrocatalytic ceramic-metallic (cermet) microsensor with a voltammetric measurement technique and advanced neural signal processing. It has been demonstrated to be flexible, rugged, and very economical to produce and deploy. Both narrow interest detectors and wide spectrum instruments have been developed around this technology. Much of this technology's strength lies in the active measurement technique employed. The technique involves applying voltammetry to a miniature electrocatalytic cell to produce unique chemical ''signatures'' from the analytes. These signatures are processed with neural pattern recognition algorithms to identify and quantify the components in the analyte. The neural signal processing allows for innovative sampling and analysis strategies to be employed with the microsensor. In most situations, the whole response signature from the voltammogram can be used to identify, classify, and quantify an analyte, without dissecting it into component parts. This allows an instrument to be calibrated once for a specific gas or mixture of gases by simple exposure to a multi-component standard rather than by a series of individual gases. The sampled unknown analytes can vary in composition or in concentration, the calibration, sensing, and processing methods of these active voltammetric microsensors can detect, recognize, and

  14. DESCRIPTION OF ATMOSPHERIC TRANSPORT PROCESSES IN EULERIAN AIR QUALITY MODELS

    EPA Science Inventory

    Key differences among many types of air quality models are the way atmospheric advection and turbulent diffusion processes are treated. Gaussian models use analytical solutions of the advection-diffusion equations. Lagrangian models use a hypothetical air parcel concept effecti...

  15. Proteolytic Processing Regulates Placental Growth Factor Activities*

    PubMed Central

    Hoffmann, Daniel C.; Willenborg, Sebastian; Koch, Manuel; Zwolanek, Daniela; Müller, Stefan; Becker, Ann-Kathrin A.; Metzger, Stephanie; Ehrbar, Martin; Kurschat, Peter; Hellmich, Martin; Hubbell, Jeffrey A.; Eming, Sabine A.

    2013-01-01

    Placental growth factor (PlGF) is a critical mediator of blood vessel formation, yet mechanisms of its action and regulation are incompletely understood. Here we demonstrate that proteolytic processing regulates the biological activity of PlGF. Specifically, we show that plasmin processing of PlGF-2 yields a protease-resistant core fragment comprising the vascular endothelial growth factor receptor-1 binding site but lacking the carboxyl-terminal domain encoding the heparin-binding domain and an 8-amino acid peptide encoded by exon 7. We have identified plasmin cleavage sites, generated a truncated PlGF118 isoform mimicking plasmin-processed PlGF, and explored its biological function in comparison with that of PlGF-1 and -2. The angiogenic responses induced by the diverse PlGF forms were distinct. Whereas PlGF-2 increased endothelial cell chemotaxis, vascular sprouting, and granulation tissue formation upon skin injury, these activities were abrogated following plasmin digestion. Investigation of PlGF/Neuropilin-1 binding and function suggests a critical role for heparin-binding domain/Neuropilin-1 interaction and its regulation by plasmin processing. Collectively, here we provide new mechanistic insights into the regulation of PlGF-2/Neuropilin-1-mediated tissue vascularization and growth. PMID:23645683

  16. Activation of consolidation processes of alumina ceramics

    NASA Astrophysics Data System (ADS)

    Matrenin, S. V.; Zenin, B. S.; Tayukin, R. V.

    2016-02-01

    The methods for activating sintering ceramics based on Al2O3 by mechanical activation in the planetary mill, by adding in the mixture of nanopowders (NP) Al, Al2O3, and submicron powder TiO2, and by applying the technology of spark plasma sintering (SPS) are developed. It has been shown that adding the nanopowder up to 20 wt. % Al2O3 in a coarse powder α-Al2O3 activates the sintering process resulting in increased density and hardness of the sintered alumina ceramics. Substantial effect of increasing density of alumina ceramics due to adding the submicron powder TiO2 in the compound of initial powder mixtures has been established.

  17. Nitrate transport and transformation processes in unsaturated porous media

    USGS Publications Warehouse

    Tindall, James A.; Petrusak, Robin L.; McMahon, Peter B.

    1995-01-01

    A series of experiments was conducted on two contrasting agricultural soils to observe the influence of soil texture, preferential flow, and plants on nitrate transport and denitrification under unsaturated conditions. Calcium nitrate fertilizer was applied to the surface of four large undisturbed soil cores (30 cm diameter by 40 cm height). Two of the cores were a structured clay obtained from central Missouri and two were an unstructured fine sand obtained from central Florida. The cores were irrigated daily and maintained at a matric potential of -20 kPa, representative of soil tension in the rooting zone of irrigated agricultural fields. Volumetric water content (θ), concentration of nitrate-N in the soil solution, and nitrous oxide flux at the surface, 10, 20, and 30 cm were monitored daily. Leaching loss of surface-applied N03− -N was significant in both the sand and the clay. In unplanted sand cores, almost all of the applied nitrate was leached below 30 cm within 10 days. Gaseous N loss owing to denitrification was no greater than 2% of the nitrate-N applied to the unplanted sand cores and, in general, was less than 1 %. Although leaching was somewhat retarded in the clay cores, about 60% of the applied nitrate-N was leached from the unplanted clay soil in 5–6 weeks. Under unsaturated conditions, the clay had little to no tendency to denitrify despite the greater moisture content of the clay and retarded leaching of nitrate in the clay. The planted sand cores had surprisingly large gaseous N loss owing to denitrification, as much as 17% of the nitrate-N. Results from both the clay and sand experiments show that the dynamics of nitrate transport and transformation in unsaturated soils are affected by small, localized variations in the soil moisture content profile, the gaseous diffusion coefficient of the soil, the rate at which the nitrate pulse passes through the soil, the solubility of N2O and N2 and the diffusion of the gasses through the soil

  18. Nitrate transport and transformation processes in unsaturated porous media

    NASA Astrophysics Data System (ADS)

    Tindall, James A.; Petrusak, Robin L.; McMahon, Peter B.

    1995-07-01

    A series of experiments was conducted on two contrasting agricultural soils to observe the influence of soil texture, preferential flow, and plants on nitrate transport and denitrification under unsaturated conditions. Calcium nitrate fertilizer was applied to the surface of four large undisturbed soil cores (30 cm diameter by 40 cm height). Two of the cores were a structured clay obtained from central Missouri and two were an unstructured fine sand obtained from central Florida. The cores were irrigated daily and maintained at a matric potential of -20 kPa, representative of soil tension in the rooting zone of irrigated agricultural fields. Volumetric water content (θ), concentration of nitrate-N in the soil solution, and nitrous oxide flux at the surface, 10, 20, and 30 cm were monitored daily. Leaching loss of surface-applied N0 3- -N was significant in both the sand and the clay. In unplanted sand cores, almost all of the applied nitrate was leached below 30 cm within 10 days. Gaseous N loss owing to denitrification was no greater than 2% of the nitrate-N applied to the unplanted sand cores and, in general, was less than 1 %. Although leaching was somewhat retarded in the clay cores, about 60% of the applied nitrate-N was leached from the unplanted clay soil in 5-6 weeks. Under unsaturated conditions, the clay had little to no tendency to denitrify despite the greater moisture content of the clay and retarded leaching of nitrate in the clay. The planted sand cores had surprisingly large gaseous N loss owing to denitrification, as much as 17% of the nitrate-N. Results from both the clay and sand experiments show that the dynamics of nitrate transport and transformation in unsaturated soils are affected by small, localized variations in the soil moisture content profile, the gaseous diffusion coefficient of the soil, the rate at which the nitrate pulse passes through the soil, the solubility of N 2O and N 2 and the diffusion of the gasses through the soil

  19. Silver Nanoparticle Transport Through Soil: Illuminating the Pore-Scale Processes

    NASA Astrophysics Data System (ADS)

    Molnar, I. L.; Willson, C. S.; Gerhard, J.; O'Carroll, D. M.

    2015-12-01

    For nanoparticle transport through soil, the pore-scale (i.e., tens to hundreds of grains and pores) is a crucial intermediate scale which links nanoparticle-surface interactions with field-scale transport behaviour. However, very little information exists on how nanoparticles behave within real three-dimensional pore spaces. As a result, pore-scale processes are poorly characterized for nanoparticle systems and, subsequently, continuum-scale transport models struggle to describe commonly observed 'anomalous' behaviour such as extended tailing. This knowledge gap is due to two primary factors: an inability to experimentally observe nanoparticles within real pore spaces, and the computationally expensive models required to simulate nanoparticle movement. However, due to recent advances in Synchrotron X-Ray Computed Microtomography (SXCMT), it is now possible to quantify in-situ pore-scale nanoparticle concentrations during transport through real 3-dimensional porous media [1]. Employing this SXCMT quantification method to examine real nanoparticle/soil transport experiments has yielded new insights into the pore-scale processes governing nanoparticle transport. By coupling SXCMT nanoparticle quantification method with Computational Fluid Dynamics (CFD) simulations we are able to construct a better picture of how nanoparticles flow through real pore spaces. This talk presents SXCMT/CFD analyses of three silver nanoparticle transport experiments. Silver nanoparticles were flushed through three different sands to characterize the influence of grain distribution and retention rates on pore-scale flow and transport processes. These CFD/SXCMT analyses illuminate how processes such as temporary hydraulic retention govern nanoparticle transport. In addition, the observed distributions of pore water velocities and nanoparticle mass flow rates challenge the standard conceptual model of nanoparticle transport, suggesting that pore-scale processes require explicit consideration

  20. TRANSPORT

    EPA Science Inventory

    Presentation outline: transport principles, effective solubility; gasoline composition; and field examples (plume diving).
    Presentation conclusions: MTBE transport follows from - phyiscal and chemical properties and hydrology. Field examples show: MTBE plumes > benzene plu...

  1. A COMSOL-GEMS interface for modeling coupled reactive-transport geochemical processes

    NASA Astrophysics Data System (ADS)

    Azad, Vahid Jafari; Li, Chang; Verba, Circe; Ideker, Jason H.; Isgor, O. Burkan

    2016-07-01

    An interface was developed between COMSOL MultiphysicsTM finite element analysis software and (geo)chemical modeling platform, GEMS, for the reactive-transport modeling of (geo)chemical processes in variably saturated porous media. The two standalone software packages are managed from the interface that uses a non-iterative operator splitting technique to couple the transport (COMSOL) and reaction (GEMS) processes. The interface allows modeling media with complex chemistry (e.g. cement) using GEMS thermodynamic database formats. Benchmark comparisons show that the developed interface can be used to predict a variety of reactive-transport processes accurately. The full functionality of the interface was demonstrated to model transport processes, governed by extended Nernst-Plank equation, in Class H Portland cement samples in high pressure and temperature autoclaves simulating systems that are used to store captured carbon dioxide (CO2) in geological reservoirs.

  2. CALIBRATION OF SUBSURFACE BATCH AND REACTIVE-TRANSPORT MODELS INVOLVING COMPLEX BIOGEOCHEMICAL PROCESSES

    EPA Science Inventory

    In this study, the calibration of subsurface batch and reactive-transport models involving complex biogeochemical processes was systematically evaluated. Two hypothetical nitrate biodegradation scenarios were developed and simulated in numerical experiments to evaluate the perfor...

  3. Magnetic Processing of Structural Components for Transportation Vehicles

    SciTech Connect

    Mackiewicz-Ludtka, G.; Ludtka, G. M.; Fleming, S.; del Prado Villasana, J.

    2011-09-30

    The specific goal of this project was to develop and evaluate the effect of magnetic processing as a viable and new technology to manufacture side‐rails for heavy trucks; and to demonstrate the applicability of this technology for an industrial truck/automotive process. The targeted performance enhancements for this project were to increase the hardness or strength of two families of alloys (comparable carbon contents but one alloy system incorporating hardenability improving additions of titanium and boron) by 15 to 20%. Thermomagnetic processing has been shown to make significant and unprecedented, simultaneous improvements in yield strength and ultimate tensile strength with no loss of ductility for the truck rail application investigated in this project. Improvements in the ultimate tensile strength and yield strength in the range 20 to 30% have been measured even for the lower hardenability alloy samples that only received a very low magnetic field tempering treatment at a tempering temperature that was 67% lower than the current non-magnetic field enhanced commercial process and for a brief tempering time of 20% of the time required in their current process at the higher temperature. These significant developments, that require further demonstration and investigation on current commercial and other alloy systems, promise the evolution of a much more energy efficient and lower-carbon footprint process to be used in the future to produce stronger, tougher, and lighter weight truck rails. The property increases in the truck rails themselves will enable lighter weight truck side-rails to be produced which will reduce the overall weight of heavy duty trucks which will reduce fuel consumption and be an enabler of the goals of the DOE EERE SuperTruck Program where fuel consumption reductions of 50% are targeted for the future generation of trucks.

  4. Study of salt transport processes in Delaware Bay

    USGS Publications Warehouse

    Walters, Roy

    1992-01-01

    The study described here is a subset of a broader climate-related study, and is focused primarily on salinity intrusion into Delaware Bay and River. Given changes in freshwater discharge into the Delaware River as determined from the larger study, and given probable sea level rise estimates, the purpose here is to calculate the distribution of salinity within Delaware Bay and River. The approach adopted for this study is composed of two parts: an analysis of existing physical data in order to derive a basic understanding of the salt dynamics, and numerical simulation of future conditions based on this analysis. There are two important constraints in the model used: it must resolve the spatial scales important to the salt dynamics, and it must be sufficiently efficient to allow extensive sensitivity studies. This has led to the development of a 3D model that uses harmonic decomposition in time and irregular finite elements in space. All nonlinear terms are retained in the governing equations, including quadratic bottom stress, advection, and wave transport (continuity nonlinearity). These equations are coupled to the advection-diffusion equation for salt so that density gradient forcing is included in the momentum equations. Although this study is still in progress, the model has reproduced sea level variations and the 3D structure of tidal and residual currents very well. In addition, the study has addressed the effects of a 1-meter rise in mean sea level on hydrodynamics of the study area. Current work is focused on salt dynamics.

  5. Field and theoretical aspects of explosive volcanic transport processes

    SciTech Connect

    Valentine, G.A.

    1988-12-01

    Chapter 1 presents results of a study of deposits at the base of the large-volume Peach Springs Tuff ignimbrite (referred to as layer 1). The layer 1 deposits are interpreted to record initial blasting and pyroclastic surge events at the beginning of the eruption. Changes in bedding structures with increasing flow distance are related to the decreasing sediment load of the surges and possibly to shocks in the surges. In Chapter 2 stratified glow theory is applied to pyroclastic surges. Particle transport is assumed to be turbulent suspension. The discussion centers on the Rouse, Froude, and Richardson numbers, and the Brunt-Vaisala frequency. Chapter 3 presents results of simulations Plinian eruption columns based upon numerical solution of the time-dependent, two-phase, compressible Navier-Stokes equations. Consideration of dimensionless groups define conditions leading to column collapse. Collapsing fountains form pyroclastic flows that consist of low-concentration fronts, relatively thick heads, vortex development along the top surfaces, and rising clouds of buoyant ash. The presence of coarse-grained proximal deposits primarily reflects tephra sorting within the eruption column before collapse. 154 refs., 32 figs., 2 tabs.

  6. Processing activities for STS-91 continue in OPF Bay 2

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Processing activities for STS-91 continue in KSC's Orbiter Processing Facility Bay 2. The payload bay of Space Shuttle Discovery is relatively empty as installation of the Get Away Special (GAS) canisters begins. Two GAS canisters can be seen in the center of the photograph. On the left is G-648, a Canadian Space Agency-sponsored study on manufactured organic thin film by the physical vapor transport method, and on the right is a can with hundreds of commemorative flags to be flown on the mission. STS-91 is scheduled to launch aboard the Space Shuttle Discovery for the ninth and final docking with the Russian Space Station Mir from KSC's Launch Pad 39A on June 2 with a launch window opening around 6:04 p.m. EDT.

  7. Processing activities for STS-91 continue in OPF Bay 2

    NASA Technical Reports Server (NTRS)

    1998-01-01

    Processing activities for STS-91 continue in Orbiter Processing Facility Bay 2. Two Get Away Special (GAS) canisters are shown after their installation into Discovery's payload bay. The GAS payload G-765, in the canister on the left, is sponsored by the Canadian Space Agency and managed by C-CORE/Memorial University of Newfoundland. It is a study to understand the transport of fluids in porous media as it pertains to improving methods for enhanced oil recovery. The GAS canister on the right houses the Space Experiment Module (SEM-05), part of an educational initiative of NASA's Shuttle Small Payloads Project. STS-91 is scheduled to launch aboard the Space Shuttle Discovery for the ninth and final docking with the Russian Space Station Mir from KSC's Launch Pad 39A on June 2 with a launch window opening around 6:04 p.m. EDT.

  8. Evaluation of Transportation Vibration Associated with Relocation of Work in Process As Part of KCRIMS

    SciTech Connect

    Hartwig, Troy

    2013-04-01

    During relocation of the Kansas City Plant (KCP) from the site at Bannister Road to the site at Botts Road, work in process (WIP) within a production department must be transported. This report recommends packaging to mitigate vibration levels experienced by products during between-facility transportation. Measurements and analysis demonstrate that this mitigation results in vibration levels less than those experienced by the product during routine production processes within potentially damaging frequency ranges.

  9. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... development studies. Should the NEPA process result in a project with design concept and scope significantly... and TIP conformity with the NEPA process. 93.107 Section 93.107 Protection of Environment... Transit Laws § 93.107 Relationship of transportation plan and TIP conformity with the NEPA process....

  10. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... development studies. Should the NEPA process result in a project with design concept and scope significantly... and TIP conformity with the NEPA process. 93.107 Section 93.107 Protection of Environment... Transit Laws § 93.107 Relationship of transportation plan and TIP conformity with the NEPA process....

  11. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... studies. Should the NEPA process result in a project with design concept and scope significantly different... TIP conformity with the NEPA process. 93.107 Section 93.107 Protection of Environment ENVIRONMENTAL....107 Relationship of transportation plan and TIP conformity with the NEPA process. The degree...

  12. 40 CFR 93.107 - Relationship of transportation plan and TIP conformity with the NEPA process.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... development studies. Should the NEPA process result in a project with design concept and scope significantly... and TIP conformity with the NEPA process. 93.107 Section 93.107 Protection of Environment... Transit Laws § 93.107 Relationship of transportation plan and TIP conformity with the NEPA process....

  13. The pultrusion process for structures on advanced aerospace transportation systems

    NASA Technical Reports Server (NTRS)

    Wilson, Maywood L.; Macconochie, Ian O.; Johnson, Gary S.

    1986-01-01

    The pultrusion process, which has the potential for use in the manufacture of structures for aerospace hardware, is described. In this process, reinforcing fibers are pulled continuously through a resin system for wetting and subsequently through a heated die for polymerization. By using this process, fabrication of very long lengths of high strength, lightweight structures with consistently high quality for aerospace applications is possible. The more conventional processes involve hand lay-up, vacuum bagging, autoclaving or oven curing techniques such that lengths of structural elements produced are limited by the lengths of autoclaves or curing ovens. Several types of developmental structural elements are described in which fiberglass, aramid, graphite, and hybrid fiber systems have been used as reinforcements in an epoxy matrix and their flexural properties compared. Reinforcement fibers having tailor-made orientations which achieve tailor-made strength in the pultrusions are described. The potential aerospace applications for the pultruded products are described with advantages cited over conventional hand lay-up methods.

  14. Modeling of an Active Tablet Coating Process.

    PubMed

    Toschkoff, Gregor; Just, Sarah; Knop, Klaus; Kleinebudde, Peter; Funke, Adrian; Djuric, Dejan; Scharrer, Georg; Khinast, Johannes G

    2015-12-01

    Tablet coating is a common unit operation in the pharmaceutical industry, during which a coating layer is applied to tablet cores. The coating uniformity of tablets in a batch is especially critical for active coating, that is, coating that contains an active pharmaceutical ingredient. In recent years, discrete element method (DEM) simulations became increasingly common for investigating tablet coating. In this work, DEM was applied to model an active coating process as closely as possible, using measured model parameters and non-spherical particles. We studied how operational conditions (rotation speed, fill level, number of nozzles, and spray rate) influence the coating uniformity. To this end, simulation runs were planned and interpreted according to a statistical design of (simulation) experiments. Our general goal was to achieve a deeper understanding of the process in terms of residence times and dimensionless scaling laws. With that regard, the results were interpreted in light of analytical models. The results were presented at various detail levels, ranging from an overview of all variations to in-depth considerations. It was determined that the biggest uniformity improvement in a realistic setting was achieved by increasing the number of spray nozzles, followed by increasing the rotation speed and decreasing the fill level.

  15. Active PZT fibers: a commercial production process

    NASA Astrophysics Data System (ADS)

    Strock, Harold B.; Pascucci, Marina R.; Parish, Mark V.; Bent, Aaron A.; Shrout, Thomas R.

    1999-07-01

    Lead Zirconate Titanate (PZT) active fibers, from 80 to 250 micrometers in diameter, are produced for the AFOSR/DARPA funded Active Fiber Composites Consortium (AFCC) Program and commercial customers. CeraNova has developed a proprietary ceramics-based technology to produce PZT mono-filaments of the required purity, composition, straightness, and piezoelectric properties for use in active fiber composite structures. CeraNova's process begins with the extrusion of continuous lengths of mono-filament precursor fiber from a plasticized mix of PZT-5A powder. The care that must be taken to avoid mix contamination is described using illustrations form problems experiences with extruder wear and metallic contamination. Corrective actions are described and example microstructures are shown. The consequences of inadequate lead control are also shown. Sintered mono- filament mechanical strength and piezoelectric properties data approach bulk values but the validity of such a benchmark is questioned based on variable correlation with composite performance measures. Comb-like ceramic preform structures are shown that are being developed to minimize process and handling costs while maintaining the required mono-filament straightness necessary for composite fabrication. Lastly, actuation performance data are presented for composite structures fabricated and tested by Continuum Control Corporation. Free strain actuation in excess of 2000 microstrain are observed.

  16. The Association between Access to Public Transportation and Self-Reported Active Commuting

    PubMed Central

    Djurhuus, Sune; Hansen, Henning S.; Aadahl, Mette; Glümer, Charlotte

    2014-01-01

    Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting. PMID:25489998

  17. The association between access to public transportation and self-reported active commuting.

    PubMed

    Djurhuus, Sune; Hansen, Henning S; Aadahl, Mette; Glümer, Charlotte

    2014-12-05

    Active commuting provides routine-based regular physical activity which can reduce the risk of chronic diseases. Using public transportation involves some walking or cycling to a transit stop, transfers and a walk to the end location and users of public transportation have been found to accumulate more moderate physical activity than non-users. Understanding how public transportation characteristics are associated with active transportation is thus important from a public health perspective. This study examines the associations between objective measures of access to public transportation and self-reported active commuting. Self-reported time spent either walking or cycling commuting each day and the distance to workplace were obtained for adults aged 16 to 65 in the Danish National Health Survey 2010 (n = 28,928). Access to public transportation measures were computed by combining GIS-based road network distances from home address to public transit stops an integrating their service level. Multilevel logistic regression was used to examine the association between access to public transportation measures and active commuting. Distance to bus stop, density of bus stops, and number of transport modes were all positively associated with being an active commuter and with meeting recommendations of physical activity. No significant association was found between bus services at the nearest stop and active commuting. The results highlight the importance of including detailed measurements of access to public transit in order to identify the characteristics that facilitate the use of public transportation and active commuting.

  18. [Transport processes of Fukushima derived radioactivity in the Pacific Ocean].

    PubMed

    Aoyama, Michio

    2014-01-01

    Before the Fukushima Nuclear Power Plant 1 (FNPP1) accident, environmental (137)Cs was already detectable originating from nuclear weapon tests conducted in the late 1950s and early 1960s. In the western North Pacific Ocean, (90)Sr and (137)Cs activities in surface water were 10-100 Bqm(-3) in the late 1950s and early 1960s, then this parameter decreased gradually; (137)Cs activity in surface water subsequently decreased to around a few Bq m(-3). After the FNPP1 accident, (137)Cs and (134)Cs were released into the North Pacific Ocean by two pathways, direct discharge from the Fukushima NPP1 accident site and atmospheric deposition off Honshu Islands of Japan, east and northeast of the site. High-density observations of (137)Cs and (134)Cs in the surface water were carried out by 17 VOS cruises and several research vessel cruises between April 2011 and March 2012. The main body of radioactive surface plume of which activity exceeded 10 Bqm(-3) traveled along 40°N, and reached the International Date Line in March 2012, 1 year after the accident. The radioactive plume was confined along 40°N when the plume reached the International Date Line. Zonal speed of the radioactive plume was estimated to be about 8 cm s(-1), which is consistent with zonal speeds derived by Argo floats at the region.

  19. Identification of sorption processes and parameters for radionuclide transport in fractured rock

    NASA Astrophysics Data System (ADS)

    Dai, Zhenxue; Wolfsberg, Andrew; Reimus, Paul; Deng, Hailin; Kwicklis, Edward; Ding, Mei; Ware, Doug; Ye, Ming

    2012-01-01

    SummaryIdentification of chemical reaction processes in subsurface environments is a key issue for reactive transport modeling because simulating different processes requires developing different chemical-mathematical models. In this paper, two sorption processes (equilibrium and kinetics) are considered for modeling neptunium and uranium sorption in fractured rock. Based on different conceptualizations of the two processes occurring in fracture and/or matrix media, seven dual-porosity, multi-component reactive transport models are developed. The process models are identified with a stepwise strategy by using multi-tracer concentration data obtained from a series of transport experiments. In the first step, breakthrough data of a conservative tracer (tritium) obtained from four experiments are used to estimate the flow and non-reactive transport parameters (i.e., mean fluid residence time in fracture, fracture aperture, and matrix tortuosity) common to all the reactive transport models. In the second and third steps, by fixing the common non-reactive flow and transport parameters, the sorption parameters (retardation factor, sorption coefficient, and kinetic rate constant) of each model are estimated using the breakthrough data of reactive tracers, neptunium and uranium, respectively. Based on the inverse modeling results, the seven sorption-process models are discriminated using four model discrimination (or selection) criteria, Akaike information criterion ( AIC), modified Akaike information criterion ( AICc), Bayesian information criterion ( BIC) and Kashyap information criterion ( KIC). These criteria suggest the kinetic sorption process for modeling reactive transport of neptunium and uranium transport in both fracture and matrix. This conclusion is confirmed by two chemical criteria, the half reaction time and Damköhler number criterion.

  20. School Travel Planning: Mobilizing School and Community Resources to Encourage Active School Transportation

    ERIC Educational Resources Information Center

    Buliung, Ron; Faulkner, Guy; Beesley, Theresa; Kennedy, Jacky

    2011-01-01

    Background: Active school transport (AST), school travel using an active mode like walking, may be important to children's overall physical activity. A "school travel plan" (STP) documents a school's transport characteristics and provides an action plan to address school and neighborhood barriers to AST. Methods: We conducted a pilot STP…

  1. Transport processes investigation: A necessary first step in site scale characterization plans

    SciTech Connect

    Roepke, C.; Glass, R.J.; Brainard, J.; Mann, M.; Kriel, K.; Holt, R.; Schwing, J.

    1995-03-01

    We propose an approach, which we call the Transport Processes Investigation or TPI, to identify and verify site-scale transport processes and their controls. The TPI aids in the formulation of an accurate conceptual model of flow and transport, an essential first step in the development of a cost effective site characterization strategy. The TPI is demonstrated in the highly complex vadose zone of glacial tills that underlie the Fernald Environmental Remediation Project (FEMP) in Fernald, Ohio. As a result of the TPI, we identify and verify the pertinent flow processes and their controls, such as extensive macropore and fracture flow through layered clays, which must be included in an accurate conceptual model of site-scale contaminant transport. We are able to conclude that the classical modeling and sampling methods employed in some site characterization programs will be insufficient to characterize contaminant concentrations or distributions at contaminated or hazardous waste facilities sited in such media.

  2. Intraparticle mass transport mechanism in activated carbon adsorption of phenols

    SciTech Connect

    Furuya, E.G.; Miura, Y.; Yokomura, H.; Tajima, S.; Yamashita, S.; Chang, H.T.; Noll, K.E.

    1996-10-01

    Two parallel diffusion mechanisms, pore and surface, can control the rate of contaminant adsorption. The two mechanisms are different functions of temperature and adsorbate concentration. To develop a mechanistic design model for adsorption processes, the two mechanisms must be evaluated separately. In this paper, the authors show that the mechanisms can be separated accurately using a stepwise linearization technique. The technique can easily be incorporated in adsorption diffusion modeling. Two phenolic compounds were used in this study: p-chlorophenol (PCP) and p-nitrophenol (PNP). The application of the linearization technique is illustrated using two types of reactors: a completely mixed batch reactor and a differential reactor. The study results show that pore and surface diffusivity can be determined accurately using the linearization technique. Furthermore, the tortuosity for the absorbent can be estimated from the pore diffusivity. For PCP that is strongly adsorbed by the adsorbent, surface diffusion is the dominant mechanism controlling the intraparticle transport. For weakly adsorbed PNP, neither surface nor pore diffusion is dominant.

  3. Are the correlates of active school transport context-specific?

    PubMed Central

    Larouche, R; Sarmiento, O L; Broyles, S T; Denstel, K D; Church, T S; Barreira, T V; Chaput, J-P; Fogelholm, M; Hu, G; Kuriyan, R; Kurpad, A; Lambert, E V; Maher, C; Maia, J; Matsudo, V; Olds, T; Onywera, V; Standage, M; Tremblay, M S; Tudor-Locke, C; Zhao, P; Katzmarzyk, P T

    2015-01-01

    OBJECTIVES: Previous research consistently indicates that children who engage in active school transport (AST) are more active than their peers who use motorized modes (car or bus). However, studies of the correlates of AST have been conducted predominantly in high-income countries and have yielded mixed findings. Using data from a heterogeneous sample of 12 country sites across the world, we investigated the correlates of AST in 9–11-year olds. METHODS: The analytical sample comprised 6555 children (53.8% girls), who reported their main travel mode to school and the duration of their school trip. Potential individual and neighborhood correlates of AST were assessed with a parent questionnaire adapted from previously validated instruments. Multilevel generalized linear mixed models (GLMM) were used to examine the associations between individual and neighborhood variables and the odds of engaging in AST while controlling for the child's school. Site moderated the relationship of seven of these variables with AST; therefore we present analyses stratified by site. RESULTS: The prevalence of AST varied from 5.2 to 79.4% across sites and the school-level intra-class correlation ranged from 0.00 to 0.56. For each site, the final GLMM included a different set of correlates of AST. Longer trip duration (that is, ⩾16 min versus ⩽15 min) was associated with lower odds of AST in eight sites. Other individual and neighborhood factors were associated with AST in three sites or less. CONCLUSIONS: Our results indicate wide variability in the prevalence and correlates of AST in a large sample of children from twelve geographically, economically and culturally diverse country sites. This suggests that AST interventions should not adopt a ‘one size fits all' approach. Future research should also explore the association between psychosocial factors and AST in different countries. PMID:27152191

  4. Environmental impact assessment in urban transport planning: Exploring process-related barriers in Spanish practice

    SciTech Connect

    Soria-Lara, Julio A. Bertolini, Luca Brömmelstroet, Marco te

    2015-01-15

    The effectiveness of EIA for evaluating transport planning projects is increasingly being questioned by practitioners, institutions and scholars. The academic literature has traditionally focused more on solving content-related problems with EIA (i.e. the measurement of environmental effects) than on process-related issues (i.e. the role of EIA in the planning process and the interaction between key actors). Focusing only on technical improvements is not sufficient for rectifying the effectiveness problems of EIA. In order to address this knowledge gap, the paper explores how EIA is experienced in the Spanish planning context and offers in-depth insight into EIA process-related issues in the field of urban transport planning. From the multitude of involved actors, the research focuses on exploring the perceptions of the two main professional groups: EIA developers and transport planners. Through a web-based survey we assess the importance of process-related barriers to the effective use of EIA in urban transport planning. The analyses revealed process issues based fundamentally on unstructured stakeholders involvement and an inefficient public participation - Highlights: • Qualitative research on perceptions of EIA participants on EIA processes. • Web-based survey with different participants (EIA-developers; transport planners). • It was seen an inefficient participation of stakeholders during the EIA processes.

  5. Modeling fiber dynamics and transport in the carding process

    NASA Astrophysics Data System (ADS)

    Wibberly, Leonard Daniel

    1999-12-01

    A carding machine processes short, crimped fibers by feeding disorganized tufts onto a rotating cylinder coated with wires that engage the fibers. This cylinder works in conjunction with pun of smaller cylinders (carding stations) dig are simply coated and rotating at carefully calibrated speeds in order to separate, redistribute, align and straighten the fibers. This process produces a relatively uniform sheet of fibers with properties desirable for the textile industry. One method used to analyze the processing of the fibers is to insert a small number of easily identified tracer fibers in the card and observe their behavior at different stages throughout the card. In a similar manner, this research develops a technique to follow a representative sampling of theoretical fibers through a structure simulating the card, complete with forces attributable to the presence of other fibers, the surrounding air, and the wires on the surfaces. In this work a model of the card is proposed consisting of three essential elements. First, equations are developed to estimate the density and velocity of the overall fiber mass with a partial differential equation (PDE) derived from a random-walk formulation of the fiber motion in an interface between two surfaces. Next, a numerical solution is obtained for the steady state Navier-Stokes equations for air-flow in the space between the three rotating cylinders of a single carding station. Finally, these velocities and densities are applied to the dynamics of individual fibers, each represented as a chain of elastic-jointed segments in a moving fluid, subject to viscous drag, with the possibility of being tugged at some point with a fixed velocity by either a wire on the surface or another fiber. All of these elements are tied into the overall structure of a simple card with three rotating Cylinders, interfaces between cylinders, triangular cavity, fiber input and output points and the transfer of fibers between surfaces. Fibers are

  6. Electric Pulse Discharge Activated Carbon Supercapacitors for Transportation Application

    NASA Astrophysics Data System (ADS)

    Nayak, Subhadarshi; Agrawal, Jyoti

    2012-03-01

    ScienceTomorrow is developing a high-speed, low-cost process for synthesizing high-porosity electrodes for electrochemical double-layer capacitors. Four types of coal (lignite, subbituminous, bituminous, and anthracite) were used as precursor materials for spark discharge activation with multiscale porous structure. The final porosity and pore distribution depended, among other factors, on precursor type. The high gas content in low-grade carbon resulted in mechanical disintegration, whereas high capacitance was attained in higher-grade coal. The properties, including capacitance, mechanical robustness, and internal conductivity, were excellent when the cost is taken into consideration.

  7. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 15 Commerce and Foreign Trade 2 2010-01-01 2010-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  8. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 15 Commerce and Foreign Trade 2 2011-01-01 2011-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  9. 15 CFR 400.31 - Manufacturing and processing activity; criteria.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 15 Commerce and Foreign Trade 2 2012-01-01 2012-01-01 false Manufacturing and processing activity... ZONES BOARD Manufacturing and Processing Activity-Reviews § 400.31 Manufacturing and processing activity....” When evaluating zone and subzone manufacturing and processing activity, either as proposed in...

  10. Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter

    DOE PAGES

    Grossmann, Nina; Vakkasoglu, Ahmet S.; Hulpke, Sabine; ...

    2014-11-07

    The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the converved aspartate, whichmore » coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. As a result, our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate.« less

  11. Mechanistic determinants of the directionality and energetics of active export by a heterodimeric ABC transporter

    SciTech Connect

    Grossmann, Nina; Vakkasoglu, Ahmet S.; Hulpke, Sabine; Abele, Rupert; Gaudet, Rachelle; Tampé, Robert

    2014-11-07

    The ATP-binding cassette (ABC) transporter associated with antigen processing (TAP) participates in immune surveillance by moving proteasomal products into the endoplasmic reticulum (ER) lumen for major histocompatibility complex class I loading and cell surface presentation to cytotoxic T cells. Here we delineate the mechanistic basis for antigen translocation. Notably, TAP works as a molecular diode, translocating peptide substrates against the gradient in a strict unidirectional way. We reveal the importance of the D-loop at the dimer interface of the two nucleotide-binding domains (NBDs) in coupling substrate translocation with ATP hydrolysis and defining transport vectoriality. Substitution of the converved aspartate, which coordinates the ATP-binding site, decreases NBD dimerization affinity and turns the unidirectional primary active pump into a passive bidirectional nucleotide-gated facilitator. Thus, ATP hydrolysis is not required for translocation per se, but is essential for both active and unidirectional transport. As a result, our data provide detailed mechanistic insight into how heterodimeric ABC exporters operate.

  12. Transport phenomena of reactive fluid flow in heterogeneous combustion processes.

    NASA Technical Reports Server (NTRS)

    Hung, W. S. Y.; Chen, C. S.; Haviland, J. K.

    1972-01-01

    A previously developed computer program was used to model two transient hybrid combustion processes involving tubes of solid Plexiglas. In the first study, representing combustion of a hybrid rocket, the oxidizing gas was oxygen, and calculations were continued sufficiently long to obtain steady-state values. Systematic variations were made in reaction rate constant, mass flow rate, and pressure, alternatively using constant and temperature dependent regression rate models for the fuel surface. Consistent results were obtained, as is evidenced by the values for the mass function of the reaction product and the flame temperature, for which plots are supplied. In the second study, fire initiation in a duct was studied, with an air mixture as the oxidizing gas. It was demonstrated that a satisfactory flame spread mechanism could be reproduced on the computer. In both of the above applications, the general, transient, two-dimensional conservation equations were represented, together with chemical reactions, solid-fuel interface conditions, and heat conduction in the solid fuel.

  13. Photoacoustic monitoring of water transport process in calcareous stone coated with biopolymers

    NASA Astrophysics Data System (ADS)

    May-Crespo, J.; Ortega-Morales, B. O.; Camacho-Chab, J. C.; Quintana, P.; Alvarado-Gil, J. J.; Gonzalez-García, G.; Reyes-Estebanez, M.; Chan-Bacab, M. J.

    2016-12-01

    Moisture is a critical control of chemical and physical processes leading to stone deterioration. These processes can be enhanced by microbial biofilms and associated exopolymers (EPS). There is limited current understanding of the water transport process across rocks covered by EPS. In the present work, we employed the photoacoustic technique to study the influence of three biopolymers (xanthan, microbactan and arabic gum) in the water transport process of two types of limestone rock of similar mineralogy but contrasting porosity. Both controls of RL (low porosity) and RP (high porosity) presented the higher values of water diffusion coefficient ( D) than biopolymer-coated samples, indicating that biopolymer layers slowed down the transport of water. This trend was steeper for RP samples as water was transported seven times faster than in the more porous rock. Important differences of D values were observed among samples coated by different biopolymers. Scanning electron microscopy and optical microscopy showed that surface topography was different between both types of rocks; adherence of coatings was seen predominantly in the less porous rocks samples. FTIR and NMR analysis showed the presence of pyruvate and acetate in microbactan and xanthan gum, suggesting their participation on adherence to the calcareous surfaces, sealing surface pores. These results indicate that water transport at rock interfaces is dependent on the chemistry of biopolymer and surface porosity. The implications for reduced water transport in stone conservation under the influence of biopolymers include both enhanced and lower deterioration rates along with altered efficiency of biocide treatment of epilithic biofilms.

  14. Effects of surfactants and thermodynamic activity of model active ingredient on transport over plant leaf cuticle.

    PubMed

    Fagerström, Anton; Kocherbitov, Vitaly; Ruzgas, Tautgirdas; Westbye, Peter; Bergström, Karin; Engblom, Johan

    2013-03-01

    The main objective of this study was to investigate the mechanism of molecular transport across the cuticle of Clivia leaves. In vitro diffusion methodology was used to investigate the transport of a systemic fungicide, tebuconazole, over a model silicone membrane, enzymatically isolated cuticle membranes, and dermatomed leaves. It was shown that dermatomed leaves may replace enzymatically isolated cuticles. Furthermore, the effects of two surfactants, C(10)EO(7) and C(8)G(1.6), on the fungicide transport were investigated. Tebuconazole cuticle permeation was described using Fick's first law of diffusion, expressed by the thermodynamic activity of the solute in the membrane. A new method for calculation of diffusion coefficients in the membrane is proposed. To access the thermodynamic activity of the fungicide in the membranes, sorption isotherms of tebuconazole in the membrane materials studied were recorded. The thermodynamic activity of the fungicide in aqueous solutions was calculated from solubility data. For that purpose, the effect of surfactants on tebuconazole solubility was studied. The results show that addition of surfactants allows for higher concentrations of tebuconazole available for penetration. Nonetheless, at a fixed fungicide thermodynamic activity, all formulations produced the same flux over the silicone membrane independently on the fungicide concentration. This shows that the driving force across non-responding membranes is the gradient of thermodynamic activity, rather than the gradient of the fungicide concentration. In case of leaves, surfactants induced the same quantitative increase in both flux and diffusion coefficient of solute in the cuticle, while the cuticle-water partition coefficient was unaffected.

  15. Propulsion/ASME Rocket-Based Combined Cycle Activities in the Advanced Space Transportation Program Office

    NASA Technical Reports Server (NTRS)

    Hueter, Uwe; Turner, James

    1998-01-01

    NASA's Office Of Aeronautics and Space Transportation Technology (OASTT) has establish three major coals. "The Three Pillars for Success". The Advanced Space Transportation Program Office (ASTP) at the NASA's Marshall Space Flight Center in Huntsville,Ala. focuses on future space transportation technologies under the "Access to Space" pillar. The Advanced Reusable Technologies (ART) Project, part of ASTP, focuses on the reusable technologies beyond those being pursued by X-33. The main activity over the past two and a half years has been on advancing the rocket-based combined cycle (RBCC) technologies. In June of last year, activities for reusable launch vehicle (RLV) airframe and propulsion technologies were initiated. These activities focus primarily on those technologies that support the year 2000 decision to determine the path this country will take for Space Shuttle and RLV. In February of this year, additional technology efforts in the reusable technologies were awarded. The RBCC effort that was completed early this year was the initial step leading to flight demonstrations of the technology for space launch vehicle propulsion. Aerojet, Boeing-Rocketdyne and Pratt & Whitney were selected for a two-year period to design, build and ground test their RBCC engine concepts. In addition, ASTROX, Pennsylvania State University (PSU) and University of Alabama in Huntsville also conducted supporting activities. The activity included ground testing of components (e.g., injectors, thrusters, ejectors and inlets) and integrated flowpaths. An area that has caused a large amount of difficulty in the testing efforts is the means of initiating the rocket combustion process. All three of the prime contractors above were using silane (SiH4) for ignition of the thrusters. This follows from the successful use of silane in the NASP program for scramjet ignition. However, difficulties were immediately encountered when silane (an 80/20 mixture of hydrogen/silane) was used for rocket

  16. Evaluation of Activity Concentration Values and Doses due to the Transport of Low Level Radioactive Material

    SciTech Connect

    Rawl, Richard R; Scofield, Patricia A; Leggett, Richard Wayne; Eckerman, Keith F

    2010-04-01

    The International Atomic Energy Agency (IAEA) initiated an international Coordinated Research Project (CRP) to evaluate the safety of transport of naturally occurring radioactive material (NORM). This report presents the United States contribution to that IAEA research program. The focus of this report is on the analysis of the potential doses resulting from the transport of low level radioactive material. Specific areas of research included: (1) an examination of the technical approach used in the derivation of exempt activity concentration values and a comparison of the doses associated with the transport of materials included or not included in the provisions of Paragraph 107(e) of the IAEA Safety Standards, Regulations for the Safe Transport of Radioactive Material, Safety Requirements No. TS-R-1; (2) determination of the doses resulting from different treatment of progeny for exempt values versus the A{sub 1}/A{sub 2} values; and (3) evaluation of the dose justifications for the provisions applicable to exempt materials and low specific activity materials (LSA-I). It was found that the 'previous or intended use' (PIU) provision in Paragraph 107(e) is not risk informed since doses to the most highly exposed persons (e.g., truck drivers) are comparable regardless of intended use of the transported material. The PIU clause can also have important economic implications for co-mined ores and products that are not intended for the fuel cycle but that have uranium extracted as part of their industrial processing. In examination of the footnotes in Table 2 of TS-R-1, which identifies the progeny included in the exempt or A1/A2 values, there is no explanation of how the progeny were selected. It is recommended that the progeny for both the exemption and A{sub 1}/A{sub 2} values should be similar regardless of application, and that the same physical information should be used in deriving the limits. Based on the evaluation of doses due to the transport of low-level NORM

  17. Neoclassical plasma viscosity and transport processes in non-axisymmetric tori

    NASA Astrophysics Data System (ADS)

    Shaing, K. C.; Ida, K.; Sabbagh, S. A.

    2015-11-01

    Neoclassical transport processes are important to the understanding of plasma confinement physics in doubly periodic magnetized toroidal plasmas, especially, after the impact of the momentum confinement on the particle and energy confinement is recognized. Real doubly periodic tori in general are non-axisymmetric, with symmetric tori as a special case. An eight-moment approach to transport theory with plasma density N, plasma pressure p, mass flow velocity V and heat flow q as independent variables is adopted. Transport processes are dictated by the solutions of the momentum and heat flux balance equations. For toroidal plasma confinement devices, the first order (in the gyro-radius ordering) plasma flows are on the magnetic surface to guarantee good plasma confinement and are thus two-dimensional. Two linearly independent components of the momentum equation are required to determine the flows completely. Once this two-dimensional flow is relaxed, i.e. the momentum equation reaches a steady state, plasmas become ambipolar, and all the transport fluxes are determined through the flux-force relation. The flux-force relation is derived both from the kinetic definitions for the transport fluxes and from the manipulation of the momentum and heat flux balance equations to illustrate the nature of the transport fluxes by examining their corresponding driven forces and their roles in the momentum and heat flux balance equations. Steady-state plasma flows are determined by the components of the stress and heat stress tensors in the momentum and heat flux balance equations. This approach emphasizes the pivotal role of the momentum equation in the transport processes and is particularly useful in modelling plasma flows in experiments. The methodology for neoclassical transport theory is applied to fluctuation-driven transport fluxes in the quasilinear theory to unify these two theories. Experimental observations in tokamaks and stellarators for the physics discussed are

  18. Synthesis, processing, and transport of Pseudomonas aeruginosa elastase.

    PubMed

    Kessler, E; Safrin, M

    1988-11-01

    Three cell-associated elastase precursors with approximate molecular weights of 60,000 (P), 56,000 (Pro I), and 36,000 (Pro II) were identified in Pseudomonas aeruginosa cells by pulse-labeling with [35S]methionine and immunoprecipitation. In the absence of inhibitors, cells of a wild-type strain as well as those of the secretion-defective mutant PAKS 18 accumulated Pro II as the only elastase-related radioactive protein. EDTA but not EGTA [ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid] inhibited the formation of Pro II, and this inhibition was accompanied by the accumulation of Pro I. P accumulated in cells labeled in the presence of ethanol (with or without EDTA), dinitrophenol plus EDTA, or carbonyl cyanide m-chlorophenyl hydrazone plus EDTA. Pro I and Pro II were localized to the periplasm, and as evident from pulse-chase experiments, Pro I was converted to the mature extracellular enzyme with Pro II as an intermediate of the reaction. P was located to the membrane fraction. Pro I but not Pro II was immunoprecipitated by antibodies specific to a protein of about 20,000 molecular weight (P20), which, as we showed before (Kessler and Safrin, J. Bacteriol. 170:1215-1219, 1988), forms a complex with an inactive periplasmic elastase precursor of about 36,000 molecular weight. Our results suggest that the elastase is made by the cells as a preproenzyme (P), containing a signal sequence of about 4,000 molecular weight and a "pro" sequence of about 20,000 molecular weight. Processing and export of the preproenzyme involve the formation of two periplasmic proenzyme species: proelastase I (56 kilodaltons [kDa]) and proelastase II (36 kDa). The former is short-lived, whereas proelastase II accumulates temporarily in the periplasm, most likely as a complex with the 20-kDa propeptide released from proelastase I upon conversion to proelastase II. The final step in elastase secretion seems to required both the proteolytic removal of a small peptide

  19. Structure of the transporter associated with antigen processing trapped by herpes simplex virus.

    PubMed

    Oldham, Michael L; Grigorieff, Nikolaus; Chen, Jue

    2016-12-09

    The transporter associated with antigen processing (TAP) is an ATP-binding cassette (ABC) transporter essential to cellular immunity against viral infection. Some persistent viruses have evolved strategies to inhibit TAP so that they may go undetected by the immune system. The herpes simplex virus for example evades immune surveillance by blocking peptide transport with a small viral protein ICP47. In this study, we determined the structure of human TAP bound to ICP47 by electron cryo-microscopy (cryo-EM) to 4.0 Å. The structure shows that ICP47 traps TAP in an inactive conformation distinct from the normal transport cycle. The specificity and potency of ICP47 inhibition result from contacts between the tip of the helical hairpin and the apex of the transmembrane cavity. This work provides a clear molecular description of immune evasion by a persistent virus. It also establishes the molecular structure of TAP to facilitate mechanistic studies of the antigen presentation process.

  20. Imaging on a Shoestring: Cost-Effective Technologies for Probing Vadose Zone Transport Processes

    NASA Astrophysics Data System (ADS)

    Corkhill, C.; Bridge, J. W.; Barns, G.; Fraser, R.; Romero-Gonzalez, M.; Wilson, R.; Banwart, S.

    2010-12-01

    Key barriers to the widespread uptake of imaging technology for high spatial resolution monitoring of porous media systems are cost and accessibility. X-ray tomography, magnetic resonance imaging (MRI), gamma and neutron radiography require highly specialised equipment, controlled laboratory environments and/or access to large synchrotron facilities. Here we present results from visible light, fluorescence and autoradiographic imaging techniques developed at low cost and applied in standard analytical laboratories, adapted where necessary at minimal capital expense. UV-visible time lapse fluorescence imaging (UV-vis TLFI) in a transparent thin bed chamber enabled microspheres labelled with fluorescent dye and a conservative fluorophore solute (disodium fluorescein) to be measured simultaneously in saturated, partially-saturated and actively draining quartz sand to elucidate empirical values for colloid transport and deposition parameters distributed throughout the flow field, independently of theoretical approximations. Key results include the first experimental quantification of the effects of ionic strength and air-water interfacial area on colloid deposition above a capillary fringe, and the first direct observations of particle mobilisation and redeposition by moving saturation gradients during drainage. UV-vis imaging was also used to study biodegradation and reactive transport in a variety of saturated conditions, applying fluorescence as a probe for oxygen and nitrate concentration gradients, pH, solute transport parameters, reduction of uranium, and mapping of two-dimensional flow fields around a model dipole flow borehole system to validate numerical models. Costs are low: LED excitation sources (< US 50), flow chambers (US 200) and detectors (although a complete scientific-grade CCD set-up costs around US$ 8000, robust datasets can be obtained using a commercial digital SLR camera) mean that set-ups can be flexible to meet changing experimental

  1. Transport processes and mutual interactions of three bacterial strains in saturated porous media

    NASA Astrophysics Data System (ADS)

    Stumpp, Christine; Lawrence, John R.; Hendry, M. Jim; Maloszewski, Pitor

    2010-05-01

    Transport processes of the bacterial strains Klebsiella oxytoca, Burkholderia cepacia G4PR-1 and Pseudomonas sp #5 were investigated in saturated column experiments to study the differences in transport characteristics and the mutual interactions of these strains during transport. Soil column experiments (114 mm long x 33 mm in diameter) were conducted with constant water velocities (3.9-5.7 cm/h) through a medium to coarse grained silica sand. All experiments were performed in freshly packed columns in quadruplicate. Chloride was used as tracer to determine the mean transit time, dispersivity and flow rate. It was injected as a pulse into the columns together with the bacterial strains suspended in artificial groundwater medium. In the first setup, each strain was investigated alone. In the second setup, transport processes were performed injecting two strains simultaneously. Finally, the transport characteristics were studied in successive experiments when one bacterium was resident on the sand grains prior to the introduction of the second strain. In all experiments the peak C/Co bacterial concentrations were attenuated with respect to the conservative tracer chloride and a well defined tailing was observed. A one dimensional mathematical model for advective-dispersive transport that accounts for irreversible and reversible sorption was used to analyze the bacterial breakthrough curves and tailing patterns. It was shown that the sorption parameters were different for the three strains that can be explained by the properties of the bacteria. For the species Klebsiella oxytoca and Burkholderia cepacia G4PR-the transport parameters were mostly in the same range independent of the experimental setup. However, Pseudomonas sp #5, which is a motile bacterium, showed differences in the breakthrough curves and sorption parameters during the experiments. The simultaneous and successive experiments indicated an influence on the reversible sorption processes when another

  2. Littoral transport rates in the Santa Barbara Littoral Cell: a process-based model analysis

    USGS Publications Warehouse

    Elias, E. P. L.; Barnard, Patrick L.; Brocatus, John

    2009-01-01

    Identification of the sediment transport patterns and pathways is essential for sustainable coastal zone management of the heavily modified coastline of Santa Barbara and Ventura County (California, USA). A process-based model application, based on Delft3D Online Morphology, is used to investigate the littoral transport potential along the Santa Barbara Littoral Cell (between Point Conception and Mugu Canyon). An advanced optimalization procedure is applied to enable annual sediment transport computations by reducing the ocean wave climate in 10 wave height - direction classes. Modeled littoral transport rates compare well with observed dredging volumes, and erosion or sedimentation hotspots coincide with the modeled divergence and convergence of the transport gradients. Sediment transport rates are strongly dependent on the alongshore variation in wave height due to wave sheltering, diffraction and focusing by the Northern Channel Islands, and the local orientation of the geologically-controlled coastline. Local transport gradients exceed the net eastward littoral transport, and are considered a primary driver for hot-spot erosion.

  3. Modeling the coupled mechanics, transport, and growth processes in collagen tissues.

    SciTech Connect

    Holdych, David J.; Nguyen, Thao D.; Klein, Patrick A.; in't Veld, Pieter J.; Stevens, Mark Jackson

    2006-11-01

    The purpose of this project is to develop tools to model and simulate the processes of self-assembly and growth in biological systems from the molecular to the continuum length scales. The model biological system chosen for the study is the tendon fiber which is composed mainly of Type I collagen fibrils. The macroscopic processes of self-assembly and growth at the fiber scale arise from microscopic processes at the fibrillar and molecular length scales. At these nano-scopic length scales, we employed molecular modeling and simulation method to characterize the mechanical behavior and stability of the collagen triple helix and the collagen fibril. To obtain the physical parameters governing mass transport in the tendon fiber we performed direct numerical simulations of fluid flow and solute transport through an idealized fibrillar microstructure. At the continuum scale, we developed a mixture theory approach for modeling the coupled processes of mechanical deformation, transport, and species inter-conversion involved in growth. In the mixture theory approach, the microstructure of the tissue is represented by the species concentration and transport and material parameters, obtained from fibril and molecular scale calculations, while the mechanical deformation, transport, and growth processes are governed by balance laws and constitutive relations developed within a thermodynamically consistent framework.

  4. Correlated activity supports efficient cortical processing

    PubMed Central

    Hung, Chou P.; Cui, Ding; Chen, Yueh-peng; Lin, Chia-pei; Levine, Matthew R.

    2015-01-01

    Visual recognition is a computational challenge that is thought to occur via efficient coding. An important concept is sparseness, a measure of coding efficiency. The prevailing view is that sparseness supports efficiency by minimizing redundancy and correlations in spiking populations. Yet, we recently reported that “choristers”, neurons that behave more similarly (have correlated stimulus preferences and spontaneous coincident spiking), carry more generalizable object information than uncorrelated neurons (“soloists”) in macaque inferior temporal (IT) cortex. The rarity of choristers (as low as 6% of IT neurons) indicates that they were likely missed in previous studies. Here, we report that correlation strength is distinct from sparseness (choristers are not simply broadly tuned neurons), that choristers are located in non-granular output layers, and that correlated activity predicts human visual search efficiency. These counterintuitive results suggest that a redundant correlational structure supports efficient processing and behavior. PMID:25610392

  5. Mass transport processes in the southern Scotia Sea: Evidence of paleoearthquakes

    NASA Astrophysics Data System (ADS)

    Ruano, Patricia; Bohoyo, Fernando; Galindo-Zaldívar, Jesús; Pérez, Lara F.; Hernández-Molina, F. Javier; Maldonado, Andrés; García, Marga; Medialdea, Teresa

    2014-12-01

    The southern margin of the Scotia Sea hosts the convergent boundary between the Scotia and Antarctic plates where a number of small basins are situated. Mass transport deposits (MTDs) within two of these small basins, Dove and Scan basins, reveal the importance of seismicity, slope instabilities and depositional processes in their growth patterns. Swath-bathymetry and very high-resolution seismic data show that there are over 200 MTDs in these basins in the last 100 ky record. MTD characterizations are determined on the basis of their regional distribution, shape, apparent size and depth. Their sedimentary and tectonic implications are discussed, as well as the evidence of different triggering mechanisms in this region, which is characterized at present by moderate-to-high magnitude, shallow to intermediate earthquakes. MTDs are more abundant in the Dove Basin (with lenticular and wedge shapes), suggesting that this basin was affected by active tectonics to a greater degree than the Scan Basin. This finding is significant in the overall evolutionary context of the Scotia Sea region and Scotia-Antarctic plate geodynamics. Nevertheless, other factors -volcanic activity, vigorous bottom-currents, and/or higher sedimentation rates - must also be considered for the generation of MTDs in the Scan Basin, where a variety of processes generated more diverse MTD morphologies. Paleoseismological estimations of the repeated occurrence of wedge shaped MTDs in contact with fault scarps point to potential sources of large magnitude (Mw ~ 7.2-7.3) paleoearthquakes in several sites, in agreement with the present high magnitudes of regional seismicity. This study shows MTDs to be appropriate as paleoearthquake indicators in active tectonic settings. The distribution of MTDs in the southern Scotia Sea has important implications for geodynamic and geohazard research. They may prove to be unmistakable stratigraphic markers for future basin analysis.

  6. Diversity and activity of sugar transporters in nematode-induced root syncytia

    PubMed Central

    Hofmann, Julia; Hess, Paul H.; Szakasits, Dagmar; Blöchl, Andreas; Wieczorek, Krzysztof; Daxböck-Horvath, Sabine; Bohlmann, Holger; van Bel, Aart J. E.; Grundler, Florian M. W.

    2009-01-01

    The plant-parasitic nematode Heterodera schachtii stimulates plant root cells to form syncytial feeding structures which synthesize all nutrients required for successful nematode development. Cellular re-arrangements and modified metabolism of the syncytia are accompanied by massive intra- and intercellular solute allocations. In this study the expression of all genes annotated as sugar transporters in the Arabidopsis Membrane Protein Library was investigated by Affymetrix gene chip analysis in young and fully developed syncytia compared with non-infected Arabidopsis thaliana roots. The expression of three highly up-regulated (STP12, MEX1, and GTP2) and three highly down-regulated genes (SFP1, STP7, and STP4) was analysed by quantitative RT-PCR (qRT-PCR). The most up-regulated gene (STP12) was chosen for further in-depth studies using in situ RT-PCR and a nematode development assay with a T-DNA insertion line revealing a significant reduction of male nematode development. The specific role of STP12 expression in syncytia of male juveniles compared with those of female juveniles was further shown by qRT-PCR. In order to provide evidence for sugar transporter activity across the plasma membrane of syncytia, fluorescence-labelled glucose was used and membrane potential recordings following the application of several sugars were performed. Analyses of soluble sugar pools revealed a highly specific composition in syncytia. The presented work demonstrates that sugar transporters are specifically expressed and active in syncytia, indicating a profound role in inter- and intracelluar transport processes. PMID:19487386

  7. Dopamine transporter regulates the enhancement of novelty processing by a negative emotional context.

    PubMed

    Garcia-Garcia, Manuel; Clemente, Immaculada; Domínguez-Borràs, Judith; Escera, Carles

    2010-04-01

    The dopaminergic (DA) system has been recently related the emotional modulation of cognitive processes. Moreover, patients with midbrain DA depletion, such as Parkinson's Disease (PD), have shown diminished reactivity during unpleasant events. Here, we examined the role of DA in the enhancement of novelty processing during negative emotion. Forty healthy volunteers were genotyped for the dopamine transporter (DAT) gene SLC6A3 or DAT1 and performed an auditory-visual distraction paradigm in negative and neutral emotional context conditions. 9R- individuals, associated to a lesser striatal DA display, failed to show increased distraction during negative emotion, but experienced an enhancement of the early phase of the novelty-P3 brain response, associated to the evaluation of novel events, in the negative relative to the neutral context. However, 9R+ individuals (associated to larger striatal DA display) showed larger distraction during negative emotion and larger amplitudes of the novelty-P3, irrespective of the condition. These results suggest a blunted reactivity to novelty during negative emotion in 9R- individuals due to a lesser DA display and stronger activation of the representation of novel events in the 9R+ group, due to a larger DA availability, thus reaching a ceiling effect in the neutral context condition with no further enhancement during negative emotion. The present results might help to understand the functional implications of dopamine in some neuropsychiatric disorders.

  8. Activity-based concept for transport and partitioning of ionizing organics.

    PubMed

    Trapp, Stefan; Franco, Antonio; Mackay, Don

    2010-08-15

    Ionizing chemicals, including pesticides, pharmaceuticals, and personal care products, are care products, are widely used chemicals of commerce and have been detected in the environment in large numbers. These "ionics" are subject to a variety of processes, such as dissociation, ion trap, and electrical interactions with organic matter and biota. Conventional chemodynamic concepts and models designed to treat neutral compounds do not necessarily address these processes. A new system of equations, based on activity and analogous to the fugacity approach, is suggested to describe the fate of organic ionics. The total concentration of all molecule species in a bulk compartment is determined from the product of activity 'a' and a bulk activity capacity 'B'. The concentration ratio between compartments in equilibrium depends on the activity ratio and the capacity ratio. Changes in partitioning due to pH, ionic strength, and the ion trap effect are quantified. The calculation is illustrated for two pharmaceuticals, namely the monovalent acid ibuprofen and the monovalent base trimethoprim, in a multimedia lake system. Trimethoprim is neutral at high pH but ionized at low pH, while ibuprofen exhibits the opposite. The concentration ratios of air and biota to water are shown to depend on pH. The activity approach may be used to describe transport and partitioning of multivalent ionizable organic compounds and to build multimedia fate models.

  9. Convection and bulk transport. [review of theoretical developments in low gravity processing

    NASA Technical Reports Server (NTRS)

    Brown, R. A.

    1986-01-01

    Progress in the theoretical understanding of transport phenomena for materials processing systems in a microgravity environment is assessed. Fluid experiments and processing in space may be performed without containers. Processes that are secondary on the earth may become significant in space, e.g., the natural oscillation of a fluid. Results are summarized from experiments on oscillatory behavior, the effects of electrical charge, and nonaxisymmetric disturbances in suspended drops in a microgravity environment.

  10. A vadose zone Transport Processes Investigation within the glacial till at the Fernald Environmental Management Project.

    SciTech Connect

    Schwing, J.; Roepke, Craig Senninger; Brainard, James Robert; Glass, Robert John, Jr.; Mann, Michael J. A.; Holt, Robert M.; Kriel, Kelly

    2007-08-01

    This report describes a model Transport Processes Investigation (TPI) where field-scale vadose zone flow and transport processes are identified and verified through a systematic field investigation at a contaminated DOE site. The objective of the TPI is to help with formulating accurate conceptual models and aid in implementing rational and cost effective site specific characterization strategies at contaminated sites with diverse hydrogeologic settings. Central to the TPI are Transport Processes Characterization (TPC) tests that incorporate field surveys and large-scale infiltration experiments. Hypotheses are formulated based on observed pedogenic and hydrogeologic features as well as information provided by literature searches. The field and literature information is then used to optimize the design of one or more infiltration experiments to field test the hypothesis. Findings from the field surveys and infiltration experiments are then synthesized to formulate accurate flow and transport conceptual models. Here we document a TPI implemented in the glacial till vadose zone at the Fernald Environmental Management Project (FEMP) in Fernald, Ohio, a US Department of Energy (DOE) uranium processing site. As a result of this TPI, the flow and transport mechanisms were identified through visualization of dye stain within extensive macro pore and fracture networks which provided the means for the infiltrate to bypass potential aquatards. Such mechanisms are not addressed in current vadose zone modeling and are generally missed by classical characterization methods.

  11. Active zone proteins are transported via distinct mechanisms regulated by Par-1 kinase

    PubMed Central

    Barber, Kara R.; Sherman, Michael

    2017-01-01

    Disruption of synapses underlies a plethora of neurodevelopmental and neurodegenerative disease. Presynaptic specialization called the active zone plays a critical role in the communication with postsynaptic neuron. While the role of many proteins at the active zones in synaptic communication is relatively well studied, very little is known about how these proteins are transported to the synapses. For example, are there distinct mechanisms for the transport of active zone components or are they all transported in the same transport vesicle? Is active zone protein transport regulated? In this report we show that overexpression of Par-1/MARK kinase, a protein whose misregulation has been implicated in Autism spectrum disorders (ASDs) and neurodegenerative disorders, lead to a specific block in the transport of an active zone protein component- Bruchpilot at Drosophila neuromuscular junctions. Consistent with a block in axonal transport, we find a decrease in number of active zones and reduced neurotransmission in flies overexpressing Par-1 kinase. Interestingly, we find that Par-1 acts independently of Tau-one of the most well studied substrates of Par-1, revealing a presynaptic function for Par-1 that is independent of Tau. Thus, our study strongly suggests that there are distinct mechanisms that transport components of active zones and that they are tightly regulated. PMID:28222093

  12. Glucose-induced activation of rubidium transport and water flux in sunflower root systems.

    PubMed

    Quintero, J M; Molina, R; Fournier, J M; Benlloch, M; Ramos, J

    2001-01-01

    Excised 20-d-old sunflower roots (Helianthus annuus L. cv. Sun-Gro 393) were used to study the effect of different sugars on rubidium and water fluxes. The roots sensed and absorbed glucose from the external medium inducing the activation of rubidium accumulated in the root (Rb(+) root), the flux of exuded rubidium (J(Rb)) and, to a lesser degree, the exudation rate (J(v)). These effects were also triggered by fructose, but not by 6-deoxyglucose (6-dG), a glucose analogue which is not a substrate for hexokinase (HXK). The effect of 2-deoxyglucose (2-dG), an analogue that is phosphorylated but not further metabolized, was complex, suggesting an inhibitory effect on solute transport to the xylem. The amounts of glucose required to activate rubidium and water fluxes were similar to those previously reported to regulate different processes in other plants (0.5--10 mM). When sorbitol was used instead of glucose, neither rubidium uptake (Rb(+) root plus J(Rb)) nor J(v) was activated. It is proposed that glucose present in the root plays an important signalling role in the regulation of Rb(+) (K(+)) and water transport in plant roots.

  13. Applications of Electro-Osmotic Transport in the Processing of Textiles

    SciTech Connect

    Cooper, J.F.; Krueger, R.; Hopper, R.; Cherepy, N.

    1999-11-29

    We report development of a pilot process for the industrial rinsing of fabrics. This process combines hydraulic (pressure-driven) transport with electro-osmotic transport. It reduces the total amount of water required in certain rinsing operations by a factor of about five. Cotton exhibits an electro-osmotic transport coefficient of about 6 x 10{sup -9} m{sup 2}/s-V resulting from a partial ionization of hydroxyl groups on the cellulose polymer substrate. This process applies a field transverse to the fabric to effect the movement of water in the spaces between the 10 {micro}m cotton fibers which constitute the yam. The field strength is adjusted so that the induced electro-osmotic flux is comparable to a pressure-driven flux, which moves preferentially in the more open channels between the yams. For a fixed current density, solution conductivity and electro-osmotic transport vary inversely. The process is most practical for removal of liquids of relatively low conductivity (<500 {micro}S/cm). For removal of solutions of conductivity greater than 1200 {micro}S/cm, the rate of electro-osmotic flow may be too low to benefit the rinsing process if current densities are restricted to practical levels of about 30 mA/cm{sup 2}. Electra-osmotic transport may have important applications in wet processing of extremely fine textiles, such as micro fiber fabrics. In addition to rinsing, electro-osmotic transport may also be used to speed the penetration of chemicals and dyestuffs that are applied to the surface of wet textiles.

  14. Transforming growth factor β signaling upregulates the expression of human GDP-fucose transporter by activating transcription factor Sp1.

    PubMed

    Xu, Yu-Xin; Ma, Anna; Liu, Li

    2013-01-01

    GDP-fucose transporter plays a crucial role in fucosylation of glycoproteins by providing activated fucose donor, GDP-fucose, for fucosyltransferases in the lumen of the Golgi apparatus. Fucose-containing glycans are involved in many biological processes, which are essential for growth and development. Mutations in the GDP-fucose transporter gene cause leukocyte adhesion deficiency syndrome II, a disease characterized by slow growth, mental retardation and immunodeficiency. However, no information is available regarding its transcriptional regulation. Here, by using human cells, we show that TGF-β1 specifically induces the GDP-fucose transporter expression, but not other transporters tested such as CMP-sialic acid transporter, suggesting a diversity of regulatory pathways for the expression of these transporters. The regulatory elements that are responsive to the TGF-β1 stimulation are present in the region between bp -330 and -268 in the GDP-fucose transporter promoter. We found that this region contains two identical octamer GC-rich motifs (GGGGCGTG) that were demonstrated to be essential for the transporter expression. We also show that the transcription factor Sp1 specifically binds to the GC-rich motifs in vitro and Sp1 coupled with phospho-Smad2 is associated with the promoter region covering the Sp1-binding motifs in vivo using chromatin immunoprecipitation (ChIP) assays. In addition, we further confirmed that Sp1 is essential for the GDP-fucose transporter expression stimulated by TGF-β1 using a luciferase reporter system. These results highlight the role of TGF-β signaling in regulation of the GDP-fucose transporter expression via activating Sp1. This is the first transcriptional study for any nucleotide sugar transporters that have been identified so far. Notably, TGF-β1 receptor itself is known to be modified by fucosylation. Given the essential role of GDP-fucose transporter in fucosylation, the finding that TGF-β1 stimulates the expression of

  15. Column Testing and 1D Reactive Transport Modeling to Evaluate Uranium Plume Persistence Processes

    SciTech Connect

    Johnson, Raymond H.; Morrison, Stan; Morris, Sarah; Tigar, Aaron; Dam, William; Dayvault, Jalena

    2016-04-26

    Motivation for Study: Natural flushing of contaminants at various U.S. Department of Energy Office of Legacy Management sites is not proceeding as quickly as predicted (plume persistence) Objectives: Help determine natural flushing rates using column tests. Use 1D reactive transport modeling to better understand the major processes that are creating plume persistence Approach: Core samples from under a former mill tailings area Tailings have been removed. Column leaching using lab-prepared water similar to nearby Gunnison River water. 1D reactive transport modeling to evaluate processes

  16. Role of transportation in the persuasion process: cognitive and affective responses to antidrug narratives.

    PubMed

    Banerjee, Smita C; Greene, Kathryn

    2012-01-01

    This study examined transportation effects of first- and third-person narratives as well as the role of transportation in the persuasion process. In particular, the authors evaluated the role of transportation in affecting cognitive and affective responses. Last, they addressed the relation between (a) cognitive and affective responses and (b) antidrug expectancies. Participants were 500 undergraduate students at a large northern university in the United Kingdom who were randomly assigned to 1 of 2 conditions: first- or third-person narratives on cocaine use. The results demonstrated that there was no difference between first- and third-person narratives in terms of transportation. However, overall, greater transportation was associated with more favorable cognitive responses, and more favorable cognitive response was associated with stronger anticocaine expectancies. In terms of affective responses, results indicated the mediating role of sadness and contentment in the association between transportation and anticocaine expectancies. In particular, increased transportation was associated with greater sadness and lower contentment. Lower sadness and contentment were associated with stronger anticocaine expectancies. Important theoretical and empirical implications are discussed.

  17. Trace and major element pollution originating from coal ash suspension and transport processes.

    PubMed

    Popovic, A; Djordjevic, D; Polic, P

    2001-04-01

    Coal ash obtained by coal combustion in the "Nikola Tesla A" power plant in Obrenovac, near Belgrade, Yugoslavia, is mixed with water of the Sava river and transported to the dump. In order to assess pollution caused by leaching of some minor and major elements during ash transport through the pipeline, two sets of samples (six samples each) were subjected to a modified sequential extraction. The first set consisted of coal ash samples taken immediately after combustion, while the second set was obtained by extraction with river water, imitating the processes that occur in the pipeline. Samples were extracted consecutively with distilled water and a 1 M solution of KCl, pH 7, and the differences in extractability were compared in order to predict potential pollution. Considering concentrations of seven trace elements as well as five major elements in extracts from a total of 12 samples, it can be concluded that lead and cadmium do not present an environmental threat during and immediately after ash transport to the dump. Portions of zinc, nickel and chromium are released during the ash transport, and arsenic and manganese are released continuously. Copper and iron do not present an environmental threat due to element leaching during and immediately after the coal ash suspension and transport. On the contrary, these elements, as well as chromium, become concentrated during coal ash transport. Adsorbed portions of calcium, magnesium and potassium are also leached during coal ash transport.

  18. Colloid release and transport processes in natural and model porous media

    SciTech Connect

    Roy, S.B.; Dzombak, D.A.

    1995-12-01

    Colloidal particles present in porous media may be released and transported over significant distances when contacted with water at low ionic strength. An understanding of this process is of environmental interest because suspended colloidal particles in groundwater may enhance the subsurface transport of contaminants that are sorbed on their surfaces. This research focused on the processes of colloid release and transport in natural porous media of interest in contaminant transport, i.e., high permeability materials with low fines contents. Our objective in this study was to examine the mechanisms of colloid release and transport in a natural sand, and two model systems: latex particles attached on glass beads, and kaolinite particles attached on glass beads. For the appropriate electrolyte conditions, the release of attached colloids from all three porous media was found to be substantial. The total amount of colloids released depended upon the electrolyte composition and concentration. Column effluent data could be described with an advective-dispersive transport equation for colloidal particles with first-order terms for colloid release and deposition rates, by changing the mass of colloids available for release at each electrolyte concentrations.

  19. Processes and controls of ditch erosion and suspended sediment transport in drained peatland forests

    NASA Astrophysics Data System (ADS)

    Tuukkanen, Tapio; Stenberg, Leena; Marttila, Hannu; Finér, Leena; Piirainen, Sirpa; Koivusalo, Harri; Kløve, Bjørn

    2016-04-01

    Drainage and periodic ditch cleaning are needed in peatland forests to allow adequate tree growth. The downside is that these practices usually increase erosion and transport of organic and inorganic matter to downstream waterbodies. In this study, our aim was to assess the role of hydrological factors and ditch-level bed and bank erosion processes in controlling suspended sediment (SS) transport in peatland forests after ditch cleaning. To do this, a 113 ha catchment and a nested sub-catchment (5.2 ha) in eastern Finland were instrumented for continuous hydrological and SS concentration (turbidity) measurements and for the detection of ditch bed and bank erosion with erosion pins. The impacts of ditch cleaning on instantaneous unit hydrographs were also assessed against two reference catchments. The results suggested that, in small intensively drained catchments, SS transport is likely to be limited by the availability of easily erodible sediment in the ditch network, and that ditch cleaning operations as well as preparatory bank erosion processes such as peat desiccation and frost action can be important in producing erodible sediment for transport. Detachment of soil particle from ditch banks by raindrop impact can also be an important factor explaining variations in SS concentrations in small catchments. In larger drainage areas, peak runoff characteristics may play a more dominant role in SS transport. The results give new insights into the dynamics of sediment transport in drained peatland catchments, which can be useful, for example, for planning and implementation of water conservation measures.

  20. Mechanism of active transport: free energy dissipation and free energy transduction.

    PubMed Central

    Tanford, C

    1982-01-01

    The thermodynamic pathway for "chemiosmotic" free energy transduction in active transport is discussed with an ATP-driven Ca2+ pump as an illustrative example. Two innovations are made in the analysis. (i) Free energy dissipated as heat is rigorously excluded from overall free energy bookkeeping by focusing on the dynamic equilibrium state of the chemiosmotic process. (ii) Separate chemical potential terms for free energy donor and transported ions are used to keep track of the thermodynamic state of each substrate through the reaction cycle. These procedures clarify the mechanism of free energy transduction, even without step-by-step analysis. The results show that free energy exchange must occur in its entirety among protein-bound species. Imposition of conditions for an adequate rate of physiological function further indicates (i) that the standard free energy of hydrolysis of protein-bound ATP (to yield protein-bound products) needs to differ substantially from the standard free energy of hydrolysis in solution and (ii) that binding sites for the transported ions must have different affinities when facing opposite sides of the membrane. The results also demonstrate that step-by-step "basic" free energy changes (often used in the form of free energy level diagrams) are inherently unsuited for analysis of the mechanism of free energy transduction. PMID:6216483

  1. Guanidinylated Neomycin Mediates Heparan Sulfate–dependent Transport of Active Enzymes to Lysosomes

    PubMed Central

    Sarrazin, Stéphane; Wilson, Beth; Sly, William S; Tor, Yitzhak; Esko, Jeffrey D

    2010-01-01

    Guanidinylated neomycin (GNeo) can transport bioactive, high molecular weight cargo into the interior of cells in a process that depends on cell surface heparan sulfate proteoglycans. In this report, we show that GNeo-modified quantum dots bind to cell surface heparan sulfate, undergo endocytosis and eventually reach the lysosomal compartment. An N-hydroxysuccinimide activated ester of GNeo (GNeo-NHS) was prepared and conjugated to two lysosomal enzymes, β--glucuronidase (GUS) and α--iduronidase. Conjugation did not interfere with enzyme activity and enabled binding of the enzymes to heparin-Sepharose and heparan sulfate on primary human fibroblasts. Cells lacking the corresponding lysosomal enzyme took up sufficient amounts of the conjugated enzymes to restore normal turnover of glycosaminoglycans. The high capacity of proteoglycan-mediated uptake suggests that this method of delivery might be used for enzyme replacement or introduction of foreign enzymes into cells. PMID:20442709

  2. Achieving recommended daily physical activity levels through commuting by public transportation: unpacking individual and contextual influences.

    PubMed

    Wasfi, Rania A; Ross, Nancy A; El-Geneidy, Ahmed M

    2013-09-01

    This paper estimates the amount of daily walking associated with using public transportation in a large metropolitan area and examines individual and contextual characteristics associated with walking distances. Total walking distance to and from transit was calculated from a travel diary survey for 6913 individuals. Multilevel regression modelling was used to examine the underlying factors associated with walking to public transportation. The physical activity benefits of public transportation varied along gender and socio-economic lines. Recommended minutes of daily physical activity can be achieved for public transportation users, especially train users living in affluent suburbs.

  3. Correlation between Electron Transport and Shear Alfven Activity in the National Spherical Torus Experiment

    SciTech Connect

    Stutman, D.; Delgado-Aparicio, L.; Finkenthal, M.; Tritz, K.; Gorelenkov, N.; Fredrickson, E.; Kaye, S.; Mazzucato, E.

    2009-03-20

    We report the observation of a correlation between shear Alfven eigenmode activity and electron transport in plasma regimes where the electron temperature gradient is flat, and thus the drive for temperature gradient microinstabilities is absent. Plasmas having rapid central electron transport show intense, broadband global Alfven eigenmode (GAE) activity in the 0.5-1.1 MHz range, while plasmas with low transport are essentially GAE-free. The first theoretical assessment of a GAE-electron transport connection indicates that overlapping modes can resonantly couple to the bulk thermal electrons and induce their stochastic diffusion.

  4. Gravity-Related Transport Process in Off-Axis Sputtering Deposition

    NASA Technical Reports Server (NTRS)

    Zhu, Shen; Su, Ching-Hua; Lehozeku, S. L.

    2000-01-01

    In the synthesis of epitaxial oxide films, reactive off-axis sputtering deposition techniques have demonstrated the advantages of fabricating high quality epitaxial films. Due to the collisions between the sputtered species and the residue gases, the kinetic energy of species was reduced and the transport of depositing species changed from a ballistic movement to a diffusive drift in which the transport species were almost thermalized. A gravity effect could appear in the transport process. Three transport regimes were observed when the growth pressures vary from 5 mTorr to 150 mTorr. Film growth rate, depositing orientations, crystal structure, surface morphology, and compositions were characterized. A gravity related phenomenon was revealed in film growth at the relative low growth pressures.

  5. Oxygen transport membrane system and method for transferring heat to catalytic/process reactors

    DOEpatents

    Kelly, Sean M.; Kromer, Brian R.; Litwin, Michael M.; Rosen, Lee J.; Christie, Gervase Maxwell; Wilson, Jamie R.; Kosowski, Lawrence W.; Robinson, Charles

    2016-01-19

    A method and apparatus for producing heat used in a synthesis gas production process is provided. The disclosed method and apparatus include a plurality of tubular oxygen transport membrane elements adapted to separate oxygen from an oxygen containing stream contacting the retentate side of the membrane elements. The permeated oxygen is combusted with a hydrogen containing synthesis gas stream contacting the permeate side of the tubular oxygen transport membrane elements thereby generating a reaction product stream and radiant heat. The present method and apparatus also includes at least one catalytic reactor containing a catalyst to promote the steam reforming reaction wherein the catalytic reactor is surrounded by the plurality of tubular oxygen transport membrane elements. The view factor between the catalytic reactor and the plurality of tubular oxygen transport membrane elements radiating heat to the catalytic reactor is greater than or equal to 0.5

  6. Borreliacidal activity of Borrelia metal transporter A (BmtA) binding small molecules by manganese transport inhibition.

    PubMed

    Wagh, Dhananjay; Pothineni, Venkata Raveendra; Inayathullah, Mohammed; Liu, Song; Kim, Kwang-Min; Rajadas, Jayakumar

    2015-01-01

    Borrelia burgdorferi, the causative agent of Lyme disease, utilizes manganese (Mn) for its various metabolic needs. We hypothesized that blocking Mn transporter could be a possible approach to inhibit metabolic activity of this pathogen and eliminate the infection. We used a combination of in silico protein structure prediction together with molecular docking to target the Borrelia metal transporter A (BmtA), a single known Mn transporter in Borrelia and screened libraries of FDA approved compounds that could potentially bind to the predicted BmtA structure with high affinity. Tricyclic antihistamines such as loratadine, desloratadine, and 3-hydroxydesloratadine as well as yohimbine and tadalafil demonstrated a tight binding to the in silico folded BmtA transporter. We, then, tested borreliacidal activity and dose response of the shortlisted compounds from this screen using a series of in vitro assays. Amongst the probed compounds, desloratadine exhibited potent borreliacidal activity in vitro at and above 78 μg/mL (250 μM). Borrelia treated with lethal doses of desloratadine exhibited a significant loss of intracellular Mn specifically and a severe structural damage to the bacterial cell wall. Our results support the possibility of developing a novel, targeted therapy to treat Lyme disease by targeting specific metabolic needs of Borrelia.

  7. Borreliacidal activity of Borrelia metal transporter A (BmtA) binding small molecules by manganese transport inhibition

    PubMed Central

    Wagh, Dhananjay; Pothineni, Venkata Raveendra; Inayathullah, Mohammed; Liu, Song; Kim, Kwang-Min; Rajadas, Jayakumar

    2015-01-01

    Borrelia burgdorferi, the causative agent of Lyme disease, utilizes manganese (Mn) for its various metabolic needs. We hypothesized that blocking Mn transporter could be a possible approach to inhibit metabolic activity of this pathogen and eliminate the infection. We used a combination of in silico protein structure prediction together with molecular docking to target the Borrelia metal transporter A (BmtA), a single known Mn transporter in Borrelia and screened libraries of FDA approved compounds that could potentially bind to the predicted BmtA structure with high affinity. Tricyclic antihistamines such as loratadine, desloratadine, and 3-hydroxydesloratadine as well as yohimbine and tadalafil demonstrated a tight binding to the in silico folded BmtA transporter. We, then, tested borreliacidal activity and dose response of the shortlisted compounds from this screen using a series of in vitro assays. Amongst the probed compounds, desloratadine exhibited potent borreliacidal activity in vitro at and above 78 μg/mL (250 μM). Borrelia treated with lethal doses of desloratadine exhibited a significant loss of intracellular Mn specifically and a severe structural damage to the bacterial cell wall. Our results support the possibility of developing a novel, targeted therapy to treat Lyme disease by targeting specific metabolic needs of Borrelia. PMID:25709405

  8. Physical activity associated with public transport use--a review and modelling of potential benefits.

    PubMed

    Rissel, Chris; Curac, Nada; Greenaway, Mark; Bauman, Adrian

    2012-07-01

    Active travel, particularly walking and cycling, has been recommended because of the health benefits associated with increased physical activity. Use of public transport generally involves some walking to bus stops or train stations. This paper is a systematic review of how much time is spent in physical activity among adults using public transport. It also explores the potential effect on the population level of physical activity if inactive adults in NSW, Australia, increased their walking through increased use of public transport. Of 1,733 articles, 27 met the search criteria, and nine reported on absolute measures of physical activity associated with public transport. A further 18 papers reported on factors associated with physical activity as part of public transport use. A range of 8-33 additional minutes of walking was identified from this systematic search as being attributable to public transport use. Using "bootstrapping" statistical modelling, if 20% of all inactive adults increased their walking by only 16 minutes a day for five days a week, we predict there would be a substantial 6.97% increase in the proportion of the adult population considered "sufficiently active". More minutes walked per day, or a greater uptake of public transport by inactive adults would likely lead to significantly greater increases in the adult population considered sufficiently active.

  9. Effect of Pluronic P85 on ATPase Activity of Drug Efflux Transporters

    PubMed Central

    Batrakova, Elena V.; Li, Shu; Li, Yili; Alakhov, Valery Yu.; Kabanov, Alexander V.

    2009-01-01

    Purpose Pluronic block copolymers are potent sensitizers of multi-drug resistant (MDR) cancer cells. The sensitization effect by Pluronics is a result of two processes acting in concert: i) intracellular ATP depletion, and ii) inhibition of ATPase activity of drug efflux proteins. This work characterizes effects of Pluronic P85 on ATPase activities of Pgp, MRP1, and MRP2 drug efflux transport proteins and interaction of these proteins with their substrates, vinblastine, and leucotriene C4. Methods Using membranes overexpressing Pgp, MRP1, and MRP2, the current study evaluates effects of Pluronic P85 (P85) on the kinetic parameters (Vmax, Km, Vmax/Km) of ATP hydrolysis by these ATPases. Results The decreases in the maximal reaction rates (Vmax) and increases in apparent Michaelis constants (Km) for these transporters in the presence of various concentrations of P85 were observed. The mechanism of these effects may involve i) conformational changes of the transporter due to membrane fluidization and/or ii) nonspecific steric hindrance of the drug-binding sites by P85 chains embedded into cellular membranes. The extent of these alterations was increased in the row MRP1 < MRP2 << Pgp. Conclusions These data suggest that there are unifying pathways for the inhibition of Pgp and MRPs by the block copolymer. However, the effect of P85 on Pgp ATPase activity is considerably greater compared with the effects on MRP1 and MRP2 ATPases. This may be a reason for greater inhibitory effects of Pluronic in Pgp- compared with MRP-overexpressing cells. PMID:15648254

  10. Antibotulinal activity of process cheese ingredients.

    PubMed

    Glass, Kathleen A; Johnson, Eric A

    2004-08-01

    Ingredients used in the manufacture of reduced-fat process cheese products were screened for their ability to inhibit growth of Clostridium botulinum serotypes A and B in media. Reinforced clostridial medium (RCM) supplemented with 0, 0.5, 1, 2, 3, 5, or 10% (wt/vol) of various ingredients, including a carbohydrate-based fat replacer, an enzyme-modified cheese (EMC) derived from a Blue cheese, sweet whey, modified whey protein, or whey protein concentrate, did not inhibit botulinal growth and toxin production when stored at 30 degrees C for 1 week. In contrast, RCM supplemented with 10% soy-based flavor enhancer, 10% Parmesan EMC, or 5 or 10% Cheddar EMC inhibited botulinal toxin production in media for at least 6 weeks of storage at 30 degrees C. Subsequent trials revealed that the antibotulinal effect varied significantly among 13 lots of EMC and that the antimicrobial effect was not correlated with the pH or water activity of the EMC.

  11. Energy transport processes in a brittle ductile intrusive model of the Taupo Volcanic Zone, New Zealand

    NASA Astrophysics Data System (ADS)

    Weir, Graham J.

    1998-08-01

    The implications of the findings of recent GPS and micro-seismic studies in the Taupo Volcanic Zone (TVZ), New Zealand, on models of processes transporting mass, heat and chemicals are discussed. It is argued that in addition to the well established process of groundwater convection extracting heat and chemicals by interacting with magmatic intrusives under the TVZ, that two other processes may be important. Firstly, the existence of a ductile layer with very low permeability between about 8 to 15 km depth will produce a region of `enhanced conduction' in which very high conductive fluxes of energy arise from a temperature distribution which varies exponentially with depth. Secondly, water may transport up through the ductile layer, as a result of extensional processes in the ductile region. If extension is occurring at about 8 mm/yr, then geothermal heat transfer in the TVZ of about 4200 MW is made up from about 1200 MW from the cooling of intrusives in the brittle region in the upper 8 km; of about an additional 1900 MW of conducted heat entering the brittle region from the ductile region; and about an additional 1100 MW from water transport through the ductile region. Provided this water flow has a chloride concentration similar to that emitted from nearby volcanoes, then the total chloride transport from the TVZ is about 3.5 kg/s, as suggested by average enthalpy to chloride ratios in the TVZ of about 1.2 MJ/g. The present high heat and mass transport processes in the TVZ are assumed to result from the passive filling of volume created from extensional processes under the TVZ, plus conductive and/or convective heating processes below 15 km depth.

  12. Chemical Processing and Transport in the Stratospheric Vortex and Subvortex from Satellite Measurements and Modeling

    NASA Astrophysics Data System (ADS)

    Santee, Michelle; Manney, Gloria; MacKenzie, Ian; Chipperfield, Martyn; Feng, Wuhu; Sander, Stanley; Froidevaux, Lucien; Livesey, Nathaniel; Bernath, Peter; Walker, Kaley; Boone, Chris

    A suite of atmospheric composition measurements from the Microwave Limb Sounder (MLS) on NASA's Aura satellite and the Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE-FTS) on Canada's SCISAT-1 mission is used to study chemical processing in and dispersal of chemically-processed air from the lower stratospheric polar vortices. In particular, interannual and interhemispheric variability in chlorine activation and deactivation are investigated using measurements of ClO, HCl, and ClONO2. Theoretical understanding is assessed by comparing measurements to customized runs of the SLIMCAT 3D chemical transport model. Results are shown from a newly-updated version of the model that incorporates a sophisticated microphysical scheme as a fully-coupled module, allowing polar stratospheric cloud formation and sedimentation to be calculated interactively in full-chemistry simulations. The impact of recently-published ClOOCl absorption cross sections, which yield a stratospheric ClOOCl photolysis rate substantially lower than previous estimates, on the agreement between modelled and measured chlorine species is evaluated. In addition, measurements of HNO3 and O3 and SLIMCAT results are related to mixing diagnostics to track the springtime export of denitrified, ozone-depleted air from the "subvortex", the transition zone (potential temperatures of 350-450 K) between the region above of strong confinement inside the polar vortex and the region below of less restricted exchange with lower-latitude air. Particularly over Antarctica, such mixing of processed air out of the subvortex may significantly affect the composition of the midlatitude lowermost stratosphere and upper troposphere.

  13. Growth kinetics of physical vapor transport processes: Crystal growth of the optoelectronic material mercurous chloride

    NASA Technical Reports Server (NTRS)

    Singh, N. B.; Duval, W. M.

    1991-01-01

    Physical vapor transport processes were studied for the purpose of identifying the magnitude of convective effects on the crystal growth process. The effects of convection on crystal quality were were studied by varying the aspect ratio and those thermal conditions which ultimately affect thermal convection during physical vapor transport. An important outcome of the present study was the observation that the convection growth rate increased up to a certain value and then dropped to a constant value for high aspect ratios. This indicated that a very complex transport had occurred which could not be explained by linear stability theory. Better quality crystals grown at a low Rayleigh number confirmed that improved properties are possible in convectionless environments.

  14. Physical Activity Associated with Public Transport Use—A Review and Modelling of Potential Benefits

    PubMed Central

    Rissel, Chris; Curac, Nada; Greenaway, Mark; Bauman, Adrian

    2012-01-01

    Active travel, particularly walking and cycling, has been recommended because of the health benefits associated with increased physical activity. Use of public transport generally involves some walking to bus stops or train stations. This paper is a systematic review of how much time is spent in physical activity among adults using public transport. It also explores the potential effect on the population level of physical activity if inactive adults in NSW, Australia, increased their walking through increased use of public transport. Of 1,733 articles, 27 met the search criteria, and nine reported on absolute measures of physical activity associated with public transport. A further 18 papers reported on factors associated with physical activity as part of public transport use. A range of 8–33 additional minutes of walking was identified from this systematic search as being attributable to public transport use. Using “bootstrapping” statistical modelling, if 20% of all inactive adults increased their walking by only 16 minutes a day for five days a week, we predict there would be a substantial 6.97% increase in the proportion of the adult population considered “sufficiently active”. More minutes walked per day, or a greater uptake of public transport by inactive adults would likely lead to significantly greater increases in the adult population considered sufficiently active. PMID:22851954

  15. Impact of hydrograph form on bedload transport processes in armored channels

    NASA Astrophysics Data System (ADS)

    Kenworthy, M.; Yager, E.; Yarnell, S. M.

    2015-12-01

    Nearly all channels experience unsteady flows, from gradually varying snowmelt driven hydrographs to rapidly changing rain driven or regulated hydrographs. Despite this, the impacts of hydrograph form on bedload transport processes remain poorly understood. A set of flume experiments was conducted at the University of Idaho's Stream Lab to investigate whether hydrograph form (rapid vs gradual changes in flow) alters transport rates and mobile grain sizes for a given discharge as well as armor persistence and total transport volume during a high flow event. Prior to experiments the flume was run to equilibrium with limited sediment feed to armor the bed. Experiments included four steady state runs and nine hydrograph runs that used five different hydrograph forms. The rate of change in flow between time-steps varied in the hydrographs but minimum and peak flows and total estimated transport capacity were held constant. Initial data analysis suggests that hydrograph form does indeed impact total transport volumes, transport rates, and transported grain sizes. More rapidly changing hydrographs transported a larger total volume of sediment and had greater transport rates at peak flow than hydrographs with slower rates of change. All hydrographs displayed counter-clockwise hysteresis in transport rates with the exception of the most gradually varying run. More rapidly changing hydrographs had coarser bedload material on the rising limb but finer bedload material on the falling limb compared the same flow in more gradually changing hydrographs. Many of these observations may be linked to more significant armor loss promoted by more rapid changes in flow. On the rising limb, rapid changes in flow may increase the unsteady component of shear stress to mobilize larger grains and greater volumes of sediment over short durations compared to the effects of gradual flow increases. This has the potential to destabilize the armor surface and further mobilize surface and

  16. Drug Transporter Expression and Activity in Human Hepatoma HuH-7 Cells

    PubMed Central

    Jouan, Elodie; Le Vée, Marc; Denizot, Claire; Parmentier, Yannick; Fardel, Olivier

    2016-01-01

    Human hepatoma cells may represent a valuable alternative to the use of human hepatocytes for studying hepatic drug transporters, which is now a regulatory issue during drug development. In the present work, we have characterized hepatic drug transporter expression, activity and regulation in human hepatoma HuH-7 cells, in order to determine the potential relevance of these cells for drug transport assays. HuH-7 cells displayed notable multidrug resistance-associated protein (MRP) activity, presumed to reflect expression of various hepatic MRPs, including MRP2. By contrast, they failed to display functional activities of the uptake transporters sodium taurocholate co-transporting polypeptide (NTCP), organic anion-transporting polypeptides (OATPs) and organic cation transporter 1 (OCT1), and of the canalicular transporters P-glycoprotein and breast cancer resistance protein (BCRP). Concomitantly, mRNA expressions of various sinusoidal and canalicular hepatic drug transporters were not detected (NTCP, OATP1B1, organic anion transporter 2 (OAT2), OCT1 and bile salt export pump) or were found to be lower (OATP1B3, OATP2B1, multidrug and toxin extrusion protein 1, BCRP and MRP3) in hepatoma HuH-7 cells than those found in human hepatocytes, whereas other transporters such as OAT7, MRP4 and MRP5 were up-regulated. HuH-7 cells additionally exhibited farnesoid X receptor (FXR)- and nuclear factor erythroid 2-related factor 2 (Nrf2)-related up-regulation of some transporters. Such data indicate that HuH-7 cells, although expressing rather poorly some main hepatic drug transporters, may be useful for investigating interactions of drugs with MRPs, notably MRP2, and for studying FXR- or Nrf2-mediated gene regulation. PMID:28036031

  17. Degassing Processes at Persistently Active Explosive Volcanoes

    NASA Astrophysics Data System (ADS)

    Smekens, Jean-Francois

    Among volcanic gases, sulfur dioxide (SO2) is by far the most commonly measured. More than a monitoring proxy for volcanic degassing, SO 2 has the potential to alter climate patterns. Persistently active explosive volcanoes are characterized by short explosive bursts, which often occur at periodic intervals numerous times per day, spanning years to decades. SO 2 emissions at those volcanoes are poorly constrained, in large part because the current satellite monitoring techniques are unable to detect or quantify plumes of low concentration in the troposphere. Eruption plumes also often show high concentrations of ash and/or aerosols, which further inhibit the detection methods. In this work I focus on quantifying volcanic gas emissions at persistently active explosive volcanoes and their variations over short timescales (minutes to hours), in order to document their contribution to natural SO2 flux as well as investigate the physical processes that control their behavior. In order to make these measurements, I first develop and assemble a UV ground-based instrument, and validate it against an independently measured source of SO2 at a coal-burning power plant in Arizona. I establish a measurement protocol and demonstrate that the instrument measures SO 2 fluxes with < 20 % error. Using the same protocol, I establish a record of the degassing patterns at Semeru volcano (Indonesia), a volcano that has been producing cycles of repeated explosions with periods of minutes to hours for the past several decades. Semeru produces an average of 21-71 tons of SO2 per day, amounting to a yearly output of 8-26 Mt. Using the Semeru data, along with a 1-D transient numerical model of magma ascent, I test the validity of a model in which a viscous plug at the top of the conduit produces cycles of eruption and gas release. I find that it can be a valid hypothesis to explain the observed patterns of degassing at Semeru. Periodic behavior in such a system occurs for a very narrow range

  18. Symposium on intermediate-range atmospheric-transport processes and technology assessment. [Lead Abstract

    SciTech Connect

    Not Available

    1981-10-01

    Separate abstracts were prepared for the 47 papers in this proceedings. The purpose of this meeting was to assess the state of the art of modeling atmospheric transport processes 10 to 100 km downwind of point and area sources of pollution. (KRM)

  19. Insight into sediment transport processes on saline rangeland hillslopes using three-dimensional soil microtoprgraphy changes

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Hillslope runoff and soil erosion processes play a vital role on rangeland ecosystem sustainability due to their control on resource mobility but they also have significant implications in off-site resource transport. In general, physically-based soil erosion models such as RHEM divide erosion and ...

  20. [Alteration of transport activity of proton pumps in coleoptile cells during early development stages of maize seedlings].

    PubMed

    Shishova, M F; Tankeliun, O V; Rudashevskaia, E L; Emel'ianov, V V; Shakhova, N V; Kirpichnikova, A A

    2012-01-01

    Comparative analysis of the transport activity of proton pumps (plasmalemma H+-ATPase, vacuolar H+-ATPase, and vacuolar H+-pyrophosphatase) in the membrane preparations obtained from coleoptile cells ofetiolated maize seedlings (Zea mays L.) was carried out. The highest level ofvacuolar pyrophosphatase activity was observed during the early development of coleoptile cells under growth intensification through the elongation. The role of ATPase pumps of tonoplast and plasmalemma in the transport of hydrogen ions increases during further development. The plasmalemma activity in this process is higher. When the growth stops, the activity of proton pumps becomes significantly lower. Nevertheless, their substrate specificity and sensitivity to proton pump inhibitors do not change, which can be an evidence of physiological significance of pumps in the maintenance of cell homeostasis.

  1. Policies related to active transport to and from school: a multisite case study.

    PubMed

    Eyler, Amy A; Brownson, Ross C; Doescher, Mark P; Evenson, Kelly R; Fesperman, Carrie E; Litt, Jill S; Pluto, Delores; Steinman, Lesley E; Terpstra, Jennifer L; Troped, Philip J; Schmid, Thomas L

    2008-12-01

    Active transportation to and from school (ATS) is a viable strategy to help increase physical activity among youth. ATS can be challenging because initiatives require transdisciplinary collaboration, are influenced by the built environment and are affected by numerous policies. The purpose of this study is to identify policies and factors that influence ATS initiatives. Nine elementary schools in seven states participated in this case study. Sixty-nine stakeholders were interviewed. The interviews were transcribed, coded and analyzed using a master thematic codebook. This study identified two distinct aspects of policies: 'influential factors' which are factors that might impact policies related to ATS and 'policy actions' which are policies reported by people involved in ATS initiatives that directly affected their success. Influential factors included sidewalks, crosswalks/crossing guards, funding, personal safety concerns, advocacy group involvement and others. Policy actions included policies on school speed zone, drop-off, no-transport zones, school siting, school start/dismissal time and school choice. Despite the diversity of the schools studied, similarities included influence of built environment, safety concerns, funding and transdisciplinary collaboration. Stakeholders need to work together to stimulate action and ensure successful initiatives. Influential factors appear to be important to this process.

  2. Opposite-polarity motors activate one another to trigger cargo transport in live cells

    PubMed Central

    Ally, Shabeen; Larson, Adam G.; Barlan, Kari; Rice, Sarah E.

    2009-01-01

    Intracellular transport is typically bidirectional, consisting of a series of back and forth movements. Kinesin-1 and cytoplasmic dynein require each other for bidirectional transport of intracellular cargo along microtubules; i.e., inhibition or depletion of kinesin-1 abolishes dynein-driven cargo transport and vice versa. Using Drosophila melanogaster S2 cells, we demonstrate that replacement of endogenous kinesin-1 or dynein with an unrelated, peroxisome-targeted motor of the same directionality activates peroxisome transport in the opposite direction. However, motility-deficient versions of motors, which retain the ability to bind microtubules and hydrolyze adenosine triphosphate, do not activate peroxisome motility. Thus, any pair of opposite-polarity motors, provided they move along microtubules, can activate one another. These results demonstrate that mechanical interactions between opposite-polarity motors are necessary and sufficient for bidirectional organelle transport in live cells. PMID:20038680

  3. Low band gap polymeric solar cells using solution-processable copper iodide as hole transporting layer

    NASA Astrophysics Data System (ADS)

    Chaudhary, Neeraj; Kesari, J. P.; Chaudhary, Rajiv; Patra, Asit

    2016-08-01

    In the present work, we have shown the performance of solution-processable copper iodide (CuI) as an alternative hole transporting layer (HTL) for polymeric solar cells. Optical spectra of the CuI thin film reveal highly transparent and practically no absorption in the range vis-NIR region (450-1110 nm). X-ray diffraction (XRD) patterns of CuI exhibits as a p-type semiconductor as well as crystalline nature. The photovoltaic devices were fabricated using PCDTBT and PTB7 as donor materials blended with PC71BM as an acceptor material. The power conversion efficiencies (PCEs) based on CuI as an HTL have been achieved to up to 3.04% and 4.48% for PCDTBT and PTB7 based donor materials respectively with a configuration based on ITO/CuI(40 nm)/active layer (60 nm)/Al (120 nm). This study clearly indicated that the devices made with CuI as an HTL showed superior performance than the device fabricated from PEDOT:PSS layer as an HTL. Morphological characterization of the HTL using scanning electron microscopy (SEM) and atomic force microscope (AFM) were carried for better understanding.

  4. Small-scale variability in solute transport processes in a homogeneous clay loam soil

    SciTech Connect

    Garrido, F.; Ghodrati, M.; Chendorain, M.; Campbell, C.G.

    1999-12-01

    Small-scale variations in transport parameters may have a profound influence on larger scale flow processes. Fiber-optic miniprobes (FOMPs) provide the opportunity to continuously measure solute resident concentration in small soil volumes. A 20-channel multi-plexed-FOMP system was used in repeated miscible displacements in a repacked clay loam soil column to examine small-scale, point-to-point variability in convective-dispersive transport processes. Transport parameters, measured 10 cm below the surface, were compared at two drip irrigation point densities and two fluxes. Irrigation densities of one irrigation drip point per 4 cm{sup 2} and 11 cm{sup 2} of column surface area produced similar results. The breakthrough curves measured at 0.10 cm h{sup {minus}1} had a larger immobile phase than at a flux of 1.07 cm h{sup {minus}1}. In the clay loam soil the mobile-immobile model fit the breakthrough curves better than the convective-dispersive equation (CDE), with r{sup 2} values of 99.6 and 97.1, respectively. This analysis demonstrated that dispersion and mass recovery were much more variable than pore water velocity in this repacked clay loam soil. However, even in the most variable transport conditions encountered, only 17 sampling points were necessary to describe the column average transport parameters within 20% of the mean.

  5. Hydraulics and sediment transport processes in a pool-riffle rocky mountain stream

    USGS Publications Warehouse

    Thompson, Douglas M.

    1994-01-01

    Sediment transport processes related to varying channel-bed morphology were investigated from April to November, 1993 along a 1 km pool-riffle and step-pool reach of North Saint Vrain Creek, a small mountain stream in the Northern Colorado Rocky Mountains. Three hundred sixteen 16-256 mm tracer particles placed in two separate pool-riffle-pool sequences, forty-three direct bedload measurements at three separate cross-sections in discharges ranging between 0.27-8.8 m3/s, and indirect velocity measurements at thirteen cross-sections in 23 discharges ranging between 0.23-9.2 m3/s are used to assess sediment sorting patterns and sediment transport capacity variations. An investigation of secondary flow features and wave patterns provides preliminary evidence of turbulent controls on sediment entrainment and transport, and was used to develop a conceptual model of bedload transport and channel-bed maintenance on North Saint Vrain Creek. Recirculating eddy systems provide a means to constrict flow in pools, leading to modeled velocity-reversals at high flows. Tracer particle depositional evidence also indicates higher sediment transport capacities in pools versus riffles at high flow. Modeled hydraulic conditions and depositional evidence of tracers indicates that high-flow recirculating-eddy-influenced velocity-reversals and associated turbulence may provide the primary pool maintenance processes in this channel.

  6. Turbulence and Fluid Flow: Perspectives. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Simpson, James R.

    This module is part of a series on Physical Processes in Terrestrial and Aquatic Ecosystems. The materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process.…

  7. A systematic review of interventions for promoting active transportation to school

    PubMed Central

    2011-01-01

    Background Active transportation to school is an important contributor to the total physical activity of children and adolescents. However, active school travel has declined over time, and interventions are needed to reverse this trend. The purpose of this paper is to review intervention studies related to active school transportation to guide future intervention research. Methods A systematic review was conducted to identify intervention studies of active transportation to school published in the scientific literature through January 2010. Five electronic databases and a manual search were conducted. Detailed information was extracted, including a quantitative assessment comparing the effect sizes, and a qualitative assessment using an established evaluation tool. Results We identified 14 interventions that focused on active transportation to school. These interventions mainly focused on primary school children in the United States, Australia, and the United Kingdom. Almost all the interventions used quasi-experimental designs (10/14), and most of the interventions reported a small effect size on active transportation (6/14). Conclusion More research with higher quality study designs and measures should be conducted to further evaluate interventions and to determine the most successful strategies for increasing active transportation to school. PMID:21320322

  8. Regulation of hepatic drug transporter activity and expression by organochlorine pesticides.

    PubMed

    Bucher, Simon; Le Vee, Marc; Jouan, Elodie; Fardel, Olivier

    2014-03-01

    Organochlorine (OC) pesticides constitute a major class of persistent and toxic organic pollutants, known to modulate drug-detoxifying enzymes. In the present study, OCs were demonstrated to also alter the activity and expression of human hepatic drug transporters. Activity of the sinusoidal influx transporter OCT1 (organic cation transporter 1) was thus inhibited by endosulfan, chlordane, heptachlor, lindane, and dieldrine, but not by dichlorodiphenyltrichloroethane isomers, whereas those of the canalicular efflux pumps MRP2 (multidrug resistance-associated protein 2) and BCRP (breast cancer resistance protein) were blocked by endosulfan, chlordane, heptachlor, and chlordecone; this latter OC additionally inhibited the multidrug resistance gene 1 (MDR1)/P-glycoprotein (P-gp) activity. OCs, except endosulfan, were next found to induce MDR1/P-gp and MRP2 mRNA expressions in hepatoma HepaRG cells; some of them also upregulated BCRP. By contrast, expression of sinusoidal transporters was not impaired (organic anion-transporting polypeptide (OATP) 1B1 and OATP2B1) or was downregulated (sodium taurocholate co-transporting polypeptide (NTCP) and OCT1). Such regulations of drug transporter activity and expression, depending on the respective nature of OCs and transporters, may contribute to the toxicity of OC pesticides.

  9. Multimotor transport in a system of active and inactive kinesin-1 motors.

    PubMed

    Scharrel, Lara; Ma, Rui; Schneider, René; Jülicher, Frank; Diez, Stefan

    2014-07-15

    Long-range directional transport in cells is facilitated by microtubule-based motor proteins. One example is transport in a nerve cell, where small groups of motor proteins, such as kinesins and cytoplasmic dynein, work together to ensure the supply and clearance of cellular material along the axon. Defects in axonal transport have been linked to Alzheimer's and other neurodegenerative diseases. However, it is not known in detail how multimotor-based cargo transport is impaired if a fraction of the motors are defective. To mimic impaired multimotor transport in vitro, we performed gliding motility assays with varying fractions of active kinesin-1 motors and inactive kinesin-1 motor mutants. We found that impaired transport manifests in multiple motility regimes: 1), a fast-motility regime characterized by gliding at velocities close to the single-molecule velocity of the active motors; 2), a slow-motility regime characterized by gliding at close-to zero velocity or full stopping; and 3), a regime in which fast and slow motilities coexist. Notably, the transition from the fast to the slow regime occurred sharply at a threshold fraction of active motors. Based on single-motor parameters, we developed a stochastic model and a mean-field theoretical description that explain our experimental findings. Our results demonstrate that impaired multimotor transport mostly occurs in an either/or fashion: depending on the ratio of active to inactive motors, transport is either performed at close to full speed or is out of action.

  10. Use of Computed Microtomography to Visualize and Quantify Pore-Scale Transport Processes

    NASA Astrophysics Data System (ADS)

    Altman, S. J.; Rivers, M.; Peplinski, W. J.; Lucero, D. A.

    2001-05-01

    Pore-scale transport processes are critical to the understanding of oil and gas reservoirs, groundwater transport and toxic and radioactive waste migration. For example, at certain sites where deep geological repositories are being studied for nuclear waste storage, diffusion in fractured crystalline rocks is thought to be an important factor in retarding radionuclide transport. Presently, there is little direct observation of heterogeneous diffusion processes in crystalline rocks as it is mostly studied by field tracer tests or bulk laboratory measurements. Computed microtomography (CMT) is being applied at GSECARS (GeoSoilEnviro Consortium for Advanced Radiation Sources) at the Argonne National Laboratory Advanced Photon Source to better understand pore-space transport processes. The technique is being applied to 1-cm diameter, crystalline rock cores from underground experimental rock laboratories in Sweden, Switzerland and Japan. Approximately 20 micron resolution in three-dimensions is achieved on these cores. The CMT images of the natural samples show pore space, but the contrast in some samples is relatively poor because the required X-ray energy was high in order to penetrate the samples. The pore space is enhanced by digital subtraction tomography. In this method, the rock is saturated with high atomic number fluid (CsCl or KI solution) and images are taken with the X-ray energy below and above the cesium or iodine K absorption edge. The difference image shows only the solution, which is present in the accessible pore space and thus reveals potential fluid transport pathways. In addition to imaging the pore space, this method can detect minerals to which the cesium sorbs and differentiate between felsic and mafic minerals in the samples. New work will concentrate on real time experiments to measure transport properties. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy

  11. Modeling water stability and transport on Mars and Iapetus: Exploring their effects on geomorphic and atmospheric processes

    NASA Astrophysics Data System (ADS)

    Rivera-Valentin, Edgard G.

    2012-05-01

    The stability and transport of water on solid planetary surfaces strongly affects both atmospheric and surfaces processes. In this work, two bodies are specifically investigated where transport of water is relevant: Iapetus and Mars. Iapetus, an icy Kronian satellite, has a drastic albedo contrast on its surface and one of the darkest surfaces in the solar system. This extreme brightness contrast is suggested to occur via the transport of water ice from the leading hemisphere to the trailing hemisphere and the poles. Here a global heat and mass transfer model is developed for Iapetus in order to study the current state of H2O transport and to make inferences about the temporal evolution of this process on its surface. On Mars, atmosphere-regolith interactions have been suggested to control the near-surface water vapor cycle. Due to the large amount of experimental values of the absorptivity of soil materials, a model is developed in order to study the effects of an active regolith on the transport of water vapor. Liquid water has been a controversial subject in the martian literature. However, there exists sufficient evidence of past standing bodies of liquid on Mars. If these paleolakes contained dissolved salts, their evolution would be drastically affected. Therefore, a model is developed in order to study the effect of dissolved salts and investigate if there exists the possibility for brine residue formation. Recent observations also strongly suggest that liquid may be possible on present-day Mars. A model is developed in order to investigate the possibility of brine flows as the source for recurring slope lineae.

  12. Nonequilibrium charge susceptibility and dynamical conductance: identification of scattering processes in quantum transport.

    PubMed

    Ness, H; Dash, L K

    2012-03-23

    We calculate the nonequilibrium charge transport properties of nanoscale junctions in the steady state and extend the concept of charge susceptibility to the nonequilibrium conditions. We show that the nonequilibrium charge susceptibility is related to the nonlinear dynamical conductance. In spectroscopic terms, both contain the same features versus applied bias when charge fluctuation occurs in the corresponding electronic resonances. However, we show that, while the conductance exhibits features at biases corresponding to inelastic scattering with no charge fluctuations, the nonequilibrium charge susceptibility does not. We suggest that measuring both the nonequilibrium conductance and charge susceptibility in the same experiment will permit us to differentiate between different scattering processes in quantum transport.

  13. Conservation laws for collisional and turbulent transport processes in toroidal plasmas with large mean flows

    NASA Astrophysics Data System (ADS)

    Sugama, H.; Nunami, M.; Nakata, M.; Watanabe, T.-H.

    2017-02-01

    A novel gyrokinetic formulation is presented by including collisional effects into the Lagrangian variational principle to yield the governing equations for background and turbulent electromagnetic fields and gyrocenter distribution functions, which can simultaneously describe classical, neoclassical, and turbulent transport processes in toroidal plasmas with large toroidal flows on the order of the ion thermal velocity. Noether's theorem modified for collisional systems and the collision operator given in terms of Poisson brackets are applied to derivation of the particle, energy, and toroidal momentum balance equations in the conservative forms, which are desirable properties for long-time global transport simulation.

  14. Calculation tool for transported geothermal energy using two-step absorption process

    SciTech Connect

    Kyle Gluesenkamp

    2016-02-01

    This spreadsheet allows the user to calculate parameters relevant to techno-economic performance of a two-step absorption process to transport low temperature geothermal heat some distance (1-20 miles) for use in building air conditioning. The parameters included are (1) energy density of aqueous LiBr and LiCl solutions, (2) transportation cost of trucking solution, and (3) equipment cost for the required chillers and cooling towers in the two-step absorption approach. More information is available in the included public report: "A Technical and Economic Analysis of an Innovative Two-Step Absorption System for Utilizing Low-Temperature Geothermal Resources to Condition Commercial Buildings"

  15. Distributed model of hydrological and sediment transport processes in large river basins in Southeast Asia

    NASA Astrophysics Data System (ADS)

    Zuliziana, S.; Tanuma, K.; Yoshimura, C.; Saavedra, O. C.

    2015-07-01

    Soil erosion and sediment transport have been modeled at several spatial and temporal scales, yet few models have been reported for large river basins (e.g., drainage areas > 100 000 km2). In this study, we propose a process-based distributed model for assessment of sediment transport at a large basin scale. A distributed hydrological model was coupled with a process-based distributed sediment transport model describing soil erosion and sedimentary processes at hillslope units and channels. The model was tested on two large river basins: the Chao Phraya River Basin (drainage area: 160 000 km2) and the Mekong River Basin (795 000 km2). The simulation over 10 years showed good agreement with the observed suspended sediment load in both basins. The average Nash-Sutcliffe efficiency (NSE) and average correlation coefficient (r) between the simulated and observed suspended sediment loads were 0.62 and 0.61, respectively, in the Chao Phraya River Basin except the lowland section. In the Mekong River Basin, the overall average NSE and r were 0.60 and 0.78, respectively. Sensitivity analysis indicated that suspended sediment load is sensitive to detachability by raindrop (k) in the Chao Phraya River Basin and to soil detachability over land (Kf) in the Mekong River Basin. Overall, the results suggest that the present model can be used to understand and simulate erosion and sediment transport in large river basins.

  16. Individual Public Transportation Accessibility is Positively Associated with Self-Reported Active Commuting

    PubMed Central

    Djurhuus, Sune; Hansen, Henning Sten; Aadahl, Mette; Glümer, Charlotte

    2014-01-01

    Background: Active commuters have lower risk of chronic disease. Understanding which of the, to some extent, modifiable characteristics of public transportation that facilitate its use is thus important in a public health perspective. The aim of the study was to examine the association between individual public transportation accessibility and self-reported active commuting, and whether the associations varied with commute distance, age, and gender. Methods: Twenty-eight thousand nine hundred twenty-eight commuters in The Capital Region of Denmark reported self-reported time spent either walking or cycling to work or study each day and the distance to work or study. Data were obtained from the Danish National Health Survey collected in February to April 2010. Individual accessibility by public transportation was calculated using a multi-modal network in a GIS. Multilevel logistic regression was used to analyze the association between accessibility, expressed as access area, and being an active commuter. Results: Public transport accessibility area based on all stops within walking and cycling distance was positively associated with being an active commuter. Distance to work, age, and gender modified the associations. Residing within 10 km commute distance and in areas of high accessibility was associated with being an active commuter and meeting the recommendations of physical activity. For the respondents above 29 years, individual public transportation accessibility was positively associated with being an active commuter. Women having high accessibility had significantly higher odds of being an active commuter compared to having a low accessibility. For men, the associations were insignificant. Conclusion: This study extends the knowledge about the driving forces of using public transportation for commuting by examining the individual public transportation accessibility. Findings suggest that transportation accessibility supports active commuting and planning

  17. Inhibition of Human Drug Transporter Activities by the Pyrethroid Pesticides Allethrin and Tetramethrin

    PubMed Central

    Chedik, Lisa; Bruyere, Arnaud; Le Vee, Marc; Stieger, Bruno; Denizot, Claire; Parmentier, Yannick; Potin, Sophie; Fardel, Olivier

    2017-01-01

    Pyrethroids are widely-used chemical insecticides, to which humans are commonly exposed, and known to alter functional expression of drug metabolizing enzymes. Limited data have additionally suggested that drug transporters, that constitute key-actors of the drug detoxification system, may also be targeted by pyrethroids. The present study was therefore designed to analyze the potential regulatory effects of these pesticides towards activities of main ATP-binding cassette (ABC) and solute carrier (SLC) drug transporters, using transporter-overexpressing cells. The pyrethroids allethrin and tetramethrin were found to inhibit various ABC and SLC drug transporters, including multidrug resistance-associated protein (MRP) 2, breast cancer resistance protein (BCRP), organic anion transporter polypeptide (OATP) 1B1, organic anion transporter (OAT) 3, multidrug and toxin extrusion transporter (MATE) 1, organic cation transporter (OCT) 1 and OCT2, with IC50 values however ranging from 2.6 μM (OCT1 inhibition by allethrin) to 77.6 μM (OAT3 inhibition by tetramethrin) and thus much higher than pyrethroid concentrations (in the nM range) reached in environmentally pyrethroid-exposed humans. By contrast, allethrin and tetramethrin cis-stimulated OATP2B1 activity and failed to alter activities of OATP1B3, OAT1 and MATE2-K, whereas P-glycoprotein activity was additionally moderately inhibited. Twelve other pyrethoids used at 100 μM did not block activities of the various investigated transporters, or only moderately inhibited some of them (inhibition by less than 50%). In silico analysis of structure-activity relationships next revealed that molecular parameters, including molecular weight and lipophilicity, are associated with transporter inhibition by allethrin/tetramethrin and successfully predicted transporter inhibition by the pyrethroids imiprothrin and prallethrin. Taken together, these data fully demonstrated that two pyrethoids, i.e., allethrin and tetramethrin, can

  18. Molecular features of the prazosin molecule required for activation of Transport-P.

    PubMed

    da Silva, Joaquim Fernando Mendes; Walters, Marcus; Al-Damluji, Saad; Ganellin, C Robin

    2008-08-01

    Closely related structural analogues of prazosin have been synthesised and tested for inhibition and activation of Transport-P in order to identify the structural features of the prazosin molecule that appear to be necessary for activation of Transport-P. So far, all the compounds tested are less active than prazosin. It is shown that the structure of prazosin appears to be very specific for the activation. Only quinazolines have been found to activate, and the presence of the 6,7-dimethoxy and 4-amino groups appears to be critically important.

  19. RESEARCH ACTIVITIES AT U.S. GOVERNMENT AGENCIES IN SUBSURFACE REACTIVE TRANSPORT MODELING

    EPA Science Inventory

    The fate of contaminants in the environment is controlled by both chemical reactions and transport phenomena in the subsurface. Our ability to understand the significance of these processes over time requires an accurate conceptual model that incorporates the various mechanisms ...

  20. Dopamine Transporter Genotype Conveys Familial Risk of Attention-Deficit/Hyperactivity Disorder through Striatal Activation

    ERIC Educational Resources Information Center

    Durston, Sarah; Fossella, John A.; Mulder, Martijn J.; Casey B. J.; Ziermans, Tim B.; Vessaz, M. Nathalie; Van Engeland, Herman

    2008-01-01

    The study examines the effect of the dopamine transporter (DAT1) genotype in attention-deficit/hyperactivity disorder (ADHD). The results confirm that DAT1 translates the genetic risk of ADHD through striatal activation.

  1. Development and testing of heat transport fluids for use in active solar heating and cooling systems

    NASA Technical Reports Server (NTRS)

    Parker, J. C.

    1981-01-01

    Work on heat transport fluids for use with active solar heating and cooling systems is described. Program objectives and how they were accomplished including problems encountered during testing are discussed.

  2. 76 FR 73020 - Agency Information Collection (Request for Transportation Expense Reimbursement): Activity Under...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-28

    ... unable to pursue training or employment without travel assistance. An agency may not conduct or sponsor... From the Federal Register Online via the Government Publishing Office DEPARTMENT OF VETERANS AFFAIRS Agency Information Collection (Request for Transportation Expense Reimbursement): Activity...

  3. Moditored unsaturated soil transport processes as a support for large scale soil and water management

    NASA Astrophysics Data System (ADS)

    Vanclooster, Marnik

    2010-05-01

    The current societal demand for sustainable soil and water management is very large. The drivers of global and climate change exert many pressures on the soil and water ecosystems, endangering appropriate ecosystem functioning. The unsaturated soil transport processes play a key role in soil-water system functioning as it controls the fluxes of water and nutrients from the soil to plants (the pedo-biosphere link), the infiltration flux of precipitated water to groundwater and the evaporative flux, and hence the feed back from the soil to the climate system. Yet, unsaturated soil transport processes are difficult to quantify since they are affected by huge variability of the governing properties at different space-time scales and the intrinsic non-linearity of the transport processes. The incompatibility of the scales between the scale at which processes reasonably can be characterized, the scale at which the theoretical process correctly can be described and the scale at which the soil and water system need to be managed, calls for further development of scaling procedures in unsaturated zone science. It also calls for a better integration of theoretical and modelling approaches to elucidate transport processes at the appropriate scales, compatible with the sustainable soil and water management objective. Moditoring science, i.e the interdisciplinary research domain where modelling and monitoring science are linked, is currently evolving significantly in the unsaturated zone hydrology area. In this presentation, a review of current moditoring strategies/techniques will be given and illustrated for solving large scale soil and water management problems. This will also allow identifying research needs in the interdisciplinary domain of modelling and monitoring and to improve the integration of unsaturated zone science in solving soil and water management issues. A focus will be given on examples of large scale soil and water management problems in Europe.

  4. Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance

    SciTech Connect

    Gu, Wenbin

    2014-08-29

    This report documents the work performed by General Motors (GM) under the Cooperative agreement No. DE-EE0000470, “Investigation of Micro- and Macro-Scale Transport Processes for Improved Fuel Cell Performance,” in collaboration with the Penn State University (PSU), University of Tennessee Knoxville (UTK), Rochester Institute of Technology (RIT), and University of Rochester (UR) via subcontracts. The overall objectives of the project are to investigate and synthesize fundamental understanding of transport phenomena at both the macro- and micro-scales for the development of a down-the-channel model that accounts for all transport domains in a broad operating space. GM as a prime contractor focused on cell level experiments and modeling, and the Universities as subcontractors worked toward fundamental understanding of each component and associated interface.

  5. Solution-processable graphene oxide as an efficient hole transport layer in polymer solar cells.

    PubMed

    Li, Shao-Sian; Tu, Kun-Hua; Lin, Chih-Cheng; Chen, Chun-Wei; Chhowalla, Manish

    2010-06-22

    The utilization of graphene oxide (GO) thin films as the hole transport and electron blocking layer in organic photovoltaics (OPVs) is demonstrated. The incorporation of GO deposited from neutral solutions between the photoactive poly(3-hexylthiophene) (P3HT):phenyl-C61-butyric acid methyl ester (PCBM) layer and the transparent and conducting indium tin oxide (ITO) leads to a decrease in recombination of electrons and holes and leakage currents. This results in a dramatic increase in the OPV efficiencies to values that are comparable to devices fabricated with PEDOT:PSS as the hole transport layer. Our results indicate that GO could be a simple solution-processable alternative to PEDOT:PSS as the effective hole transport and electron blocking layer in OPV and light-emitting diode devices.

  6. Statistics of active transport in Xenopus melanophores cells.

    SciTech Connect

    Snezhko, A.; Barlan, K.; Aranson, I. S.; Gelfand, V. I.; Materials Science Division; Northwestern Univ.

    2010-11-01

    The transport of cell cargo, such as organelles and protein complexes in the cytoplasm, is determined by cooperative action of molecular motors stepping along polar cytoskeletal elements. Analysis of transport of individual organelles generated useful information about the properties of the motor proteins and underlying cytoskeletal elements. In this work, for the first time (to our knowledge), we study collective movement of multiple organelles using Xenopus melanophores, pigment cells that translocate several thousand of pigment granules (melanosomes), spherical organelles of a diameter of {approx} 1 {micro}m. These cells disperse melanosomes in the cytoplasm in response to high cytoplasmic cAMP, while at low cAMP melanosomes cluster at the cell center. Obtained results suggest spatial and temporal organization, characterized by strong correlations between movement of neighboring organelles, with correlation length of {approx} 4 {micro}m and pair lifetime {approx} 5 s. Furthermore, velocity statistics revealed strongly non-Gaussian velocity distribution with high velocity tails demonstrating exponential behavior suggestive of strong velocity correlations. Depolymerization of vimentin intermediate filaments using a dominant-negative vimentin mutant or actin with cytochalasin B reduced correlation of behavior of individual particles. Based on our analysis, we concluded that steric repulsion is dominant, but both intermediate filaments and actin microfilaments are involved in dynamic cross-linking organelles in the cytoplasm.

  7. Disposition and transportation of surplus radioactive low specific activity nitric acid. Volume 1, Environmental Assessment

    SciTech Connect

    1995-05-01

    DOE is deactivating the PUREX plant at Hanford; this will involve the disposition of about 692,000 liters (183,000 gallons) of surplus nitric acid contaminated with low levels of U and other radionuclides. The nitric acid, designated as low specific activity, is stored in 4 storage tanks at PUREX. Five principal alternatives were evaluated: transfer for reuse (sale to BNF plc), no action, continued storage in Hanford upgraded or new facility, consolidation of DOE surplus acid, and processing the LSA nitric acid as waste. The transfer to BNF plc is the preferred alternative. From the analysis, it is concluded that the proposed disposition and transportation of the acid does not constitute a major federal action significantly affecting the quality of the human environment within the meaning of NEPA; therefore an environmental impact statement is not required.

  8. Auxin Activity of Substituted Benzoic Acids and Their Effect on Polar Auxin Transport 1

    PubMed Central

    Keitt, George W.; Baker, Robert A.

    1966-01-01

    Six dichloro-, 3 trichloro-, 2 triiodo-, and 3 heterosubstituted benzoic acids (amiben, dinoben, dicamba), and N-1-naphthylphthalamic acid have been tested for effects on growth and on polar auxin transport. Growth activity with and without kinetin was measured by effects on fresh and dry weights of 30-day cultures of fresh tobacco pith. Transport inhibition was measured by following uptake and output of IAA-2-14C through 10 mm bean epicotyl sections. The distribution of callus growth on vascularized tobacco stem segments was also observed. Avena first internode extension assays established the relative activities: dicamba > amiben > dinoben suggested by pith growth results. Growth effects of active compounds were similar with and without kinetin, except that amiben was less active with kinetin, while 2,3,6-trichlorobenzoic acid was more active with kinetin than alone. The weak auxin activity of NPA was confirmed. Transport experiments showed that NPA was the most inhibitory compound tested, followed by TIBA. Other compounds tested were at least 300 times less inhibitory to IAA transport. The best growth promoters were the least inhibitory to transport, and the most effective transport inhibitors were at best poor auxins. It is suggested that the weak auxin and auxin synergistic activity of TIBA (and perhaps 2,3-dichlorobenzoic acid) in extension growth tests arises from its inhibition of transport of endogenous or added auxin out of the sections, rather than from its intrinsic auxin activity. Chemically induced apolar callus growth on vascularized tobacco stem explants can arise from inhibition of native auxin transport, apolar growth stimulation by auxinic action of the test compound, or both. PMID:16656441

  9. Parental Involvement in Active Transport to School Initiatives: A Multi-Site Case Study

    ERIC Educational Resources Information Center

    Eyler, Amy; Baldwin, Julie; Carnoske, Cheryl; Nickelson, Jan; Troped, Philip; Steinman, Lesley; Pluto, Delores; Litt, Jill; Evenson, Kelly; Terpstra, Jennifer; Brownson, Ross; Schmid, Thomas

    2008-01-01

    Background: Increasing physical activity in youth is a recommended approach to curbing the childhood obesity epidemic. One way to help increase children's daily activity is to promote active transportation to and from school (ATS). Purpose: The purpose of this case study was to explore parental perception of, and participation in, ATS initiatives.…

  10. Membrane Transport Processes Analyzed by a Highly Parallel Nanopore Chip System at Single Protein Resolution.

    PubMed

    Urban, Michael; Vor der Brüggen, Marc; Tampé, Robert

    2016-08-16

    Membrane protein transport on the single protein level still evades detailed analysis, if the substrate translocated is non-electrogenic. Considerable efforts have been made in this field, but techniques enabling automated high-throughput transport analysis in combination with solvent-free lipid bilayer techniques required for the analysis of membrane transporters are rare. This class of transporters however is crucial in cell homeostasis and therefore a key target in drug development and methodologies to gain new insights desperately needed. The here presented manuscript describes the establishment and handling of a novel biochip for the analysis of membrane protein mediated transport processes at single transporter resolution. The biochip is composed of microcavities enclosed by nanopores that is highly parallel in its design and can be produced in industrial grade and quantity. Protein-harboring liposomes can directly be applied to the chip surface forming self-assembled pore-spanning lipid bilayers using SSM-techniques (solid supported lipid membranes). Pore-spanning parts of the membrane are freestanding, providing the interface for substrate translocation into or out of the cavity space, which can be followed by multi-spectral fluorescent readout in real-time. The establishment of standard operating procedures (SOPs) allows the straightforward establishment of protein-harboring lipid bilayers on the chip surface of virtually every membrane protein that can be reconstituted functionally. The sole prerequisite is the establishment of a fluorescent read-out system for non-electrogenic transport substrates. High-content screening applications are accomplishable by the use of automated inverted fluorescent microscopes recording multiple chips in parallel. Large data sets can be analyzed using the freely available custom-designed analysis software. Three-color multi spectral fluorescent read-out furthermore allows for unbiased data discrimination into different

  11. Severe acute respiratory syndrome coronavirus E protein transports calcium ions and activates the NLRP3 inflammasome.

    PubMed

    Nieto-Torres, Jose L; Verdiá-Báguena, Carmina; Jimenez-Guardeño, Jose M; Regla-Nava, Jose A; Castaño-Rodriguez, Carlos; Fernandez-Delgado, Raul; Torres, Jaume; Aguilella, Vicente M; Enjuanes, Luis

    2015-11-01

    Severe acute respiratory syndrome coronavirus (SARS-CoV) envelope (E) protein is a viroporin involved in virulence. E protein ion channel (IC) activity is specifically correlated with enhanced pulmonary damage, edema accumulation and death. IL-1β driven proinflammation is associated with those pathological signatures, however its link to IC activity remains unknown. In this report, we demonstrate that SARS-CoV E protein forms protein-lipid channels in ERGIC/Golgi membranes that are permeable to calcium ions, a highly relevant feature never reported before. Calcium ions together with pH modulated E protein pore charge and selectivity. Interestingly, E protein IC activity boosted the activation of the NLRP3 inflammasome, leading to IL-1β overproduction. Calcium transport through the E protein IC was the main trigger of this process. These findings strikingly link SARS-CoV E protein IC induced ionic disturbances at the cell level to immunopathological consequences and disease worsening in the infected organism.

  12. Roles of pollen-specific boron efflux transporter, OsBOR4, in the rice fertilization process.

    PubMed

    Tanaka, Nobuhiro; Uraguchi, Shimpei; Saito, Akihiro; Kajikawa, Masataka; Kasai, Koji; Sato, Yutaka; Nagamura, Yoshiaki; Fujiwara, Toru

    2013-12-01

    Arabidopsis thaliana BOR1 was the first boron (B) transporter identified in living systems. There are four AtBOR1-like genes, OsBOR1, 2, 3 and 4, present in the rice genome. We characterized the activity, expression and physiological function of OsBOR4. OsBOR4 is an active efflux transporter of B. Quantitative PCR analysis and OsBOR4 promoter-green fluorescent protein (GFP) fusion revealed that OsBOR4 was both highly and specifically expressed in pollen. We obtained five Tos17 insertion mutants of osbor4. The pollen grains were viable and development of floral organs was normal in the homozygous osbor4 mutants. We observed that in all Tos17 insertion lines tested, the frequency of osbor4 homozygous plants was lower than expected in the progeny of self-fertilized heterozygous plants. These results establish that OsBOR4 is essential for normal reproductive processes. Pollen from osbor4 homozygous plants elongated fewer tubes on wild-type stigmas, and tube elongation of mutant pollen was less efficient compared with the wild-type pollen, suggesting reduced competence of osbor4 mutant pollen. The reduced competence of mutant pollen was further supported by the crosses of independent Tos17-inserted alleles of OsBOR4. Our results suggest that OsBOR4, a boron efflux transporter, is required for normal pollen germination and/or tube elongation.

  13. Required conditions for and coincident 1/1-mode activity associated with the nonlocal electron heat transport effect on TFTR

    SciTech Connect

    Kissick, M.W.; Callen, J.D.; Fredrickson, E.D.

    1997-08-01

    A database of 71 distinct and randomly collected cold pulse cases from TFTR is analyzed. Observations show a striking parameter regime cutoff for the presence of nonlocal transient transport and coincident MHD (1/1-mode) activity as well as for changes in the radial speed of the nonlocal transport effect and changes in the sawtooth period. A nontrivial link is demonstrated between electron heat transport and MHD properties through observation of a common cutoff in the parameter n{sub e}(0)/T{sub e}(0){sup 1/2} and a common threshold in injection size for radial speed and sawtooth period changes. Auxiliary heating (via energetic neutral beams) destroys whatever process is responsible for the nonlocal transport effect, unless the discharge contains significant amounts of injected tritium. These observations are preliminary, but they represent important circumstantial evidence for mysterious propagation of changes in some MHD-related phenomenon as being responsible for a large fraction of electron heat transport. This propagation is then probably a function of n{sub e}(0)/T{sub e}(0){sup 1/2}, ion mass, and possibly beam power. An analysis of Ohmic cases shows that the cutoff in n{sub e}(0)/T{sub e}{sup 1/2} indicates the nonlocal transport effects may occur when the electrons are collisionally thermally decoupled from the ions.

  14. Bidirectional transport by molecular motors: enhanced processivity and response to external forces.

    PubMed

    Müller, Melanie J I; Klumpp, Stefan; Lipowsky, Reinhard

    2010-06-02

    Intracellular transport along cytoskeletal filaments is often mediated by two teams of molecular motors that pull on the same cargo and move in opposite directions along the filaments. We have recently shown theoretically that this bidirectional transport can be understood as a stochastic tug-of-war between the two motor teams. Here, we further develop our theory to investigate the experimentally accessible dynamic behavior of cargos transported by strong motors such as kinesin-1 or cytoplasmic dynein. By studying the run and binding times of such a cargo, we show that the properties of biological motors, such as the large ratio of stall/detachment force and the small ratio of superstall backward/forward velocity, are favorable for bidirectional cargo transport, leading to fast motion and enhanced diffusion. In addition, cargo processivity is shown to be strongly enhanced by transport via several molecular motors even if these motors are engaged in a tug-of-war. Finally, we study the motility of a bidirectional cargo under force. Frictional forces arising, e.g., from the viscous cytoplasm, lead to peaks in the velocity distribution, while external forces as exerted, e.g., by an optical trap, lead to hysteresis effects. Our results, in particular our explicit expressions for the cargo binding time and the distance of the peaks in the velocity relation under friction, are directly accessible to in vitro as well as in vivo experiments.

  15. Changes In The Characteristics of Basaltic Particles During Different Transport Processes

    NASA Astrophysics Data System (ADS)

    Craddock, R. A.; Rose, T. R.

    2014-12-01

    The physical and chemical characteristics of the grains in sedimentary deposits can provide valuable clues about transport processes, distance traveled, and provenance. A fundamental physical characteristic is particle shape, which is diagnostic of transport process as well as the distance traveled. For example, it is possible to distinguish the emplacement process of sediments based entirely on the shape of the quartz grains in the deposit [e.g., Folk, 1980]. Such basic sedimentological concepts have been applied to our interpretation of surface materials on the terrestrial planets [e.g. Cabrol et al., 2014]. However, what we know about the nature of sedimentary materials is based primarily on sediments that have weathered from felsic rocks—granite. This is true because felsic materials compose most of the landmass on the Earth. Yet, the surface of Mars is composed predominately of mafic materials—basalt—and sedimentary particles derived from basalt are much different than those derived from granite. Instead of quartz, feldspar, and heavy minerals commonly found in most terrestrial sedimentary deposits, basaltic sediments are typically composed of varying amounts of olivine, pyroxene, plagioclase, and vitric and lithic fragments. Both the persistence of basaltic particles and their specific gravities are different than particles derived from granite. These differences are important because they will affect the characteristics of basaltic sediment as it is transported by wind, water, and ice, and currently we have little to no understanding as to how basaltic sediment will weather as a function of the transport mechanism and distance. We will present preliminary analyses of typical basaltic sediments that have been transported by a variety of geologic processes in Hawaii, including details about surface texture, componentry, and the influence different sedimentary processes may have on remote sensing data. The figure below shows examples of A) sediment

  16. Fluid Dynamics Applied to Streams. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Cowan, Christina E.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module deals specifically with concepts that are basic to fluid flow and…

  17. Transpiration and Leaf Temperature. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Gates, David M.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This report introduces two models of the thermal energy budget of a leaf. Typical values for…

  18. Soil Heat Flow. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Simpson, James R.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. Soil heat flow and the resulting soil temperature distributions have ecological consequences…

  19. Light and Sound: Evolutionary Aspects. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Roseman, Leonard D.

    These materials were designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module is concerned with the exchange of energy between an organism and its environment in…

  20. Pressure and Buoyancy in Aquatic Ecosystems. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Cowan, Christina E.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module explores some of the characteristics of aquatic organisms which can be…

  1. Structure of the transporter associated with antigen processing trapped by herpes simplex virus

    PubMed Central

    Oldham, Michael L; Grigorieff, Nikolaus; Chen, Jue

    2016-01-01

    The transporter associated with antigen processing (TAP) is an ATP-binding cassette (ABC) transporter essential to cellular immunity against viral infection. Some persistent viruses have evolved strategies to inhibit TAP so that they may go undetected by the immune system. The herpes simplex virus for example evades immune surveillance by blocking peptide transport with a small viral protein ICP47. In this study, we determined the structure of human TAP bound to ICP47 by electron cryo-microscopy (cryo-EM) to 4.0 Å. The structure shows that ICP47 traps TAP in an inactive conformation distinct from the normal transport cycle. The specificity and potency of ICP47 inhibition result from contacts between the tip of the helical hairpin and the apex of the transmembrane cavity. This work provides a clear molecular description of immune evasion by a persistent virus. It also establishes the molecular structure of TAP to facilitate mechanistic studies of the antigen presentation process. DOI: http://dx.doi.org/10.7554/eLife.21829.001 PMID:27935481

  2. Recommended direct simulation Monte Carlo collision model parameters for modeling ionized air transport processes

    SciTech Connect

    Swaminathan-Gopalan, Krishnan; Stephani, Kelly A.

    2016-02-15

    A systematic approach for calibrating the direct simulation Monte Carlo (DSMC) collision model parameters to achieve consistency in the transport processes is presented. The DSMC collision cross section model parameters are calibrated for high temperature atmospheric conditions by matching the collision integrals from DSMC against ab initio based collision integrals that are currently employed in the Langley Aerothermodynamic Upwind Relaxation Algorithm (LAURA) and Data Parallel Line Relaxation (DPLR) high temperature computational fluid dynamics solvers. The DSMC parameter values are computed for the widely used Variable Hard Sphere (VHS) and the Variable Soft Sphere (VSS) models using the collision-specific pairing approach. The recommended best-fit VHS/VSS parameter values are provided over a temperature range of 1000-20 000 K for a thirteen-species ionized air mixture. Use of the VSS model is necessary to achieve consistency in transport processes of ionized gases. The agreement of the VSS model transport properties with the transport properties as determined by the ab initio collision integral fits was found to be within 6% in the entire temperature range, regardless of the composition of the mixture. The recommended model parameter values can be readily applied to any gas mixture involving binary collisional interactions between the chemical species presented for the specified temperature range.

  3. Function and repair of dental enamel - Potential role of epithelial transport processes of ameloblasts.

    PubMed

    Varga, Gábor; Kerémi, Beáta; Bori, Erzsébet; Földes, Anna

    2015-07-01

    The hardest mammalian tissue, dental enamel is produced by ameloblasts, which are electrolyte-transporting epithelial cells. Although the end product is very different, they show many similarities to transporting epithelia of the pancreas, salivary glands and kidney. Enamel is produced in a multi-step epithelial secretory process that features biomineralization which is an interplay of secreted ameloblast specific proteins and the time-specific transport of minerals, protons and bicarbonate. First, "secretory" ameloblasts form the entire thickness of the enamel layer, but with low mineral content. Then they differentiate into "maturation" ameloblasts, which remove organic matrix from the enamel and in turn further build up hydroxyapatite crystals. The protons generated by hydroxyapatite formation need to be buffered, otherwise enamel will not attain full mineralization. Buffering requires a tight pH regulation and secretion of bicarbonate by ameloblasts. The whole process has been the focus of many immunohistochemical and gene knock-out studies, but, perhaps surprisingly, no functional data existed for mineral ion transport by ameloblasts. However, recent studies including ours provided a better insight for molecular mechanism of mineral formation. The secretory regulation is not completely known as yet, but its significance is crucial. Impairing regulation retards or prevents completion of enamel mineralization and results in the development of hypomineralized enamel that easily erodes after dental eruption. Factors that impair this function are fluoride and disruption of pH regulators. Revealing these factors may eventually lead to the treatment of enamel hypomineralization related to genetic or environmentally induced malformation.

  4. Short term uptake and transport process for metformin in roots of Phragmites australis and Typha latifolia.

    PubMed

    Cui, H; Hense, B A; Müller, J; Schröder, P

    2015-09-01

    Metformin (MET) as an emerging contaminant has been detected in surface water and wastewater in numerous countries, due to insufficient retention in classical waste water treatment plants. In order to characterize the uptake of the compound during phytotreatment of waste water, a short term Pitman chamber experiment was carried out to assess the characteristics of MET uptake and transport by roots. Three different concentrations (0.5, 1.0 and 2.0 mmol L(-)(1)) were applied to cattail (Typha latifolia) and reed (Phragmites australis) roots which were used to investigate the uptake mechanism because they are frequently utilized in phytoremediation. In addition, quinidine was used as an inhibitor to assess the role of organic cation transporters (OCTs) in the uptake of MET by T. latifolia. The transport process of MET is different from carbamazepine (CBZ) and caffeine (CFN). In both T. latifolia and P. australis, the uptake processes were independent of initial concentrations. Quinidine, a known inhibitor of organic cation transporters, can significantly affect MET uptake by T. latifolia roots with inhibition ratios of 70-74%. Uptake into the root could be characterized by a linear model with R(2) values in the range of 0.881-0.999. Overall, the present study provides evidence that MET is taken up by plant roots and has the potential for subsequent translocation. OCTs could be one of the important pathways for MET uptake into the plant.

  5. Radial transport processes as a precursor to particle deposition in drinking water distribution systems.

    PubMed

    van Thienen, P; Vreeburg, J H G; Blokker, E J M

    2011-02-01

    Various particle transport mechanisms play a role in the build-up of discoloration potential in drinking water distribution networks. In order to enhance our understanding of and ability to predict this build-up, it is essential to recognize and understand their role. Gravitational settling with drag has primarily been considered in this context. However, since flow in water distribution pipes is nearly always in the turbulent regime, turbulent processes should be considered also. In addition to these, single particle effects and forces may affect radial particle transport. In this work, we present an application of a previously published turbulent particle deposition theory to conditions relevant for drinking water distribution systems. We predict quantitatively under which conditions turbophoresis, including the virtual mass effect, the Saffman lift force, and the Magnus force may contribute significantly to sediment transport in radial direction and compare these results to experimental observations. The contribution of turbophoresis is mostly limited to large particles (>50 μm) in transport mains, and not expected to play a major role in distribution mains. The Saffman lift force may enhance this process to some degree. The Magnus force is not expected to play any significant role in drinking water distribution systems.

  6. Modeling Unsaturated Flow and Transport Processes in Fractured Tuffs of Yucca Mountain

    SciTech Connect

    Wu, Yu-Shu; Lu, Guoping; Zhang, Keni; Bodvarsson, G.S.

    2003-07-15

    This paper presents a field modeling study characterizing fluid flow and tracer transport in the unsaturated zone of Yucca Mountain, Nevada, a proposed underground repository for storing high-level radioactive waste. The 500 to 700 meter thick unsaturated zone of Yucca Mountain consists of highly heterogeneous layers of anisotropic, fractured ash flow and air fall tuffs. Characterization of fluid flow and heat transfer through such a system has been a challenge due to the heterogeneities prevalent on various scales. Quantitative evaluation of water, gas, and heat flow by means of numerical simulation is essential for design and performance assessment of the repository. A three-dimensional numerical flow and transport model will be discussed. The model has been calibrated against field-measured data and takes into account the coupled processes of unsaturated flow and tracer transport in the highly heterogeneous, unsaturated fractured porous rock. The modeling approach of the model is based on a dual-continuum formulation of coupled multiphase fluid and tracer transport through fractured porous rock. As application examples, effects of current and future climates on the unsaturated zone processes are evaluated to aid in the assessment of the proposed repository's system performance.

  7. Barrier Crossing and Transport Activated by Kangaroo Fluctuations

    NASA Astrophysics Data System (ADS)

    Kostur, M.; Luczka, J.

    1999-01-01

    We study barrier crossing of Brownian particles in a bistable symmetric potential and transport of Brownian particles in spatially periodic structures, driven by both kangaroo fluctuations and thermal equilibrium noise of zero mean values. We consider exponentially and algebraically correlated kangaroo fluctuations. Starting with the full Newton--Langevin equation for the Brownian particle and by introducing scaling as well as dimensionless variables, we show that the equation is very well approximated by overdamped dynamics in which inertial effects can be neglected. We analyze properties of selected macroscopic characteristics of the system such as the mean first passage time (MFPT) of particles from one minimum of the bistable potential to the other and mean stationary velocity of particles moving in a spatially periodic potential. In dependence upon statistics of kangaroo fluctuations and temperature of the system, macroscopic characteristics exhibit distinctive non-monotonic behavior. Accordingly, there exist optimal statistics of fluctuations optimizing macroscopic characteristics.

  8. Modelling of transport and biogeochemical processes in pollution plumes: literature review and model development

    NASA Astrophysics Data System (ADS)

    Brun, Adam; Engesgaard, Peter

    2002-01-01

    A literature survey shows how biogeochemical (coupled organic and inorganic reaction processes) transport models are based on considering the complete biodegradation process as either a single- or as a two-step process. It is demonstrated that some two-step process models rely on the Partial Equilibrium Approach (PEA). The PEA assumes the organic degradation step, and not the electron acceptor consumption step, is rate limiting. This distinction is not possible in one-step process models, where consumption of both the electron donor and acceptor are treated kinetically. A three-dimensional, two-step PEA model is developed. The model allows for Monod kinetics and biomass growth, features usually included only in one-step process models. The biogeochemical part of the model is tested for a batch system with degradation of organic matter under the consumption of a sequence of electron acceptors. A second paper [J. Hydrol. 256 (2002) 230-249], reports the application of the model to a field study of biogeochemical transport processes in a landfill plume in Denmark (Vejen).

  9. Activated Transport in the Separate Layers that Form the νT=1 Exciton Condensate

    NASA Astrophysics Data System (ADS)

    Wiersma, R. D.; Lok, J. G.; Kraus, S.; Dietsche, W.; von Klitzing, K.; Schuh, D.; Bichler, M.; Tranitz, H.-P.; Wegscheider, W.

    2004-12-01

    We observe the total filling factor νT=1 quantum Hall state in a bilayer two-dimensional electron system with virtually no tunneling. We find thermally activated transport in the balanced system with a monotonic increase of the activation energy with decreasing d/ℓB below 1.65. In the imbalanced system we find activated transport in each of the layers separately, yet the activation energies show a striking asymmetry around the balance point, implying a different excitation spectrum for the separate layers forming the condensed state.

  10. Ion transport through lipid bilayers by synthetic ionophores: modulation of activity and selectivity.

    PubMed

    De Riccardis, Francesco; Izzo, Irene; Montesarchio, Daniela; Tecilla, Paolo

    2013-12-17

    The ion-coupled processes that occur in the plasma membrane regulate the cell machineries in all the living organisms. The details of the chemical events that allow ion transport in biological systems remain elusive. However, investigations of the structure and function of natural and artificial transporters has led to increasing insights about the conductance mechanisms. Since the publication of the first successful artificial system by Tabushi and co-workers in 1982, synthetic chemists have designed and constructed a variety of chemically diverse and effective low molecular weight ionophores. Despite their relative structural simplicity, ionophores must satisfy several requirements. They must partition in the membrane, interact specifically with ions, shield them from the hydrocarbon core of the phospholipid bilayer, and transport ions from one side of the membrane to the other. All these attributes require amphipathic molecules in which the polar donor set used for ion recognition (usually oxygens for cations and hydrogen bond donors for anions) is arranged on a lipophilic organic scaffold. Playing with these two structural motifs, donor atoms and scaffolds, researchers have constructed a variety of different ionophores, and we describe a subset of interesting examples in this Account. Despite the ample structural diversity, structure/activity relationships studies reveal common features. Even when they include different hydrophilic moieties (oxyethylene chains, free hydroxyl, etc.) and scaffolds (steroid derivatives, neutral or polar macrocycles, etc.), amphipathic molecules, that cannot span the entire phospholipid bilayer, generate defects in the contact zone between the ionophore and the lipids and increase the permeability in the bulk membrane. Therefore, topologically complex structures that span the entire membrane are needed to elicit channel-like and ion selective behaviors. In particular the alternate-calix[4]arene macrocycle proved to be a versatile

  11. Loads and Transport Processes of Nutrients and Pesticides in Five Agricultural Watersheds

    NASA Astrophysics Data System (ADS)

    Domagalski, J. L.; Ator, S. W.; Lampe, D. C.; Baker, N. T.; Sandstrom, M. W.; Coupe, R. H.; Dileanis, P. D.

    2006-05-01

    A comparative study of five agricultural watersheds spanning a range of climatic and hydrologic conditions was completed as part of a larger study on the transport of nutrients and pesticides in multiple environmental compartments of small watersheds. Attention was given to the role of the unsaturated zone, ground water, the ground-water/surface-water interface, overland flow, and rain to account for the loads and to determine which compounds move through the environment in similar ways. In ephemeral streams, with little or no connection to shallow ground water such as in semi-arid settings, most of the chemical transport occurs following precipitation events. In contrast, some heavily irrigated agricultural watersheds, also in semi-arid environments but where the source of irrigation water is imported surface water, experience increases in ground-water levels and year-round stream flow as a result of ground water discharge to the stream through either the stream bed or through seeps (base flow). In those systems, total nitrogen is likely to be the most important agricultural compound with respect to the annual load, while pesticide transport may be minimal. Streams with a combination of base flow and substantial overland flow are more likely to transport significant quantities of phosphorus and pesticides relative to streams dominated by ground-water base flow. Streams fed by other subsurface processes, such as discharge from tile drains, are more like the ground-water base-flow-dominated systems with respect to nitrogen, phosphorus, and pesticides. In most cases, overland flow processes transport the greatest amount of unaltered pesticide compounds. However, some pesticide degradates, such as the daughter products of atrazine and metolachlor, are transported more effectively, or accumulate to a greater degree, in the unsaturated zone and ground water relative to the parent compounds, and a substantial amount of the annual load is contributed by ground water. Rain

  12. Role of thyroxine on postnatal development of ileal active bile salt transport

    SciTech Connect

    Heubi, J.E.

    1986-08-01

    The role of thyroid hormone on the postnatal development of ileal active taurocholate transport uptake was measured by an in vitro incubation technique in Sprague-Dawley rats. In 16-day-old rats treated with pharmacological doses of L-thyroxine ileal active transport appeared precociously whose K/sub m/ was 1.60 +/- 0.48 mM and V/sub app/ was 8.09 +/- 1.14 nmol min mg dry wt , while age-matched shams had only passive diffusion of taurocholate. To determine whether enhanced endogenous secretion of thyroxine was capable of stimulating development of ileal active taurocholate transport, thyrotrophic stimulating hormone (TSH) was given on days 10-13, with uptake measured on day 16. Following TSH treatment, only passive transport for taurocholate was observed in the ileum; uptake rates were consistently higher than those for untreated controls at each study concentration. Thyroidectomy performed at age 14 days with uptake measured at age 21 days did not ablate development of ileal active transport but resulted in a significant reduction in the V/sub app/ and a significant increase in K/sub m/ compared with age-matched controls. Thyroid hormone does not appear to be obligatory for the postnatal development of ileal active taurocholate transport.

  13. Electron transfer activation of a second water channel for proton transport in [FeFe]-hydrogenase

    SciTech Connect

    Sode, Olaseni; Voth, Gregory A.

    2014-12-14

    Hydrogenase enzymes are important because they can reversibly catalyze the production of molecular hydrogen. Proton transport mechanisms have been previously studied in residue pathways that lead to the active site of the enzyme via residues Cys299 and Ser319. The importance of this pathway and these residues has been previously exhibited through site-specific mutations, which were shown to interrupt the enzyme activity. It has been shown recently that a separate water channel (WC2) is coupled with electron transport to the active site of the [FeFe]-hydrogenase. The water-mediated proton transport mechanisms of the enzyme in different electronic states have been studied using the multistate empirical valence bond reactive molecular dynamics method, in order to understand any role WC2 may have in facilitating the residue pathway in bringing an additional proton to the enzyme active site. In a single electronic state A{sup 2−}, a water wire was formed through which protons can be transported with a low free energy barrier. The remaining electronic states were shown, however, to be highly unfavorable to proton transport in WC2. A double amino acid substitution is predicted to obstruct proton transport in electronic state A{sup 2-} by closing a cavity that could otherwise fill with water near the proximal Fe of the active site.

  14. Joint source coding, transport processing, and error concealment for H.323-based packet video

    NASA Astrophysics Data System (ADS)

    Zhu, Qin-Fan; Kerofsky, Louis

    1998-12-01

    In this paper, we investigate how to adapt different parameters in H.263 source coding, transport processing and error concealment to optimize end-to-end video quality at different bitrates and packet loss rates for H.323-based packet video. First different intra coding patterns are compared and we show that the contiguous rectangle or square block pattern offers the best performance in terms of video quality in the presence of packet loss. Second, the optimal intra coding frequency is found for different bitrates and packet loss rates. The optimal number of GOB headers to be inserted in the source coding is then determined. The effect of transport processing strategies such as packetization and retransmission is also examined. For packetization, the impact of packet size and the effect of macroblock segmentation to picture quality are investigated. Finally, we show that the dejitter buffering delay can be used to the advantage for packet loss recovery with video retransmission without incurring any extra delay.

  15. Thermodynamics of Irreversible Processes Applied to Solute Transport in Non Saturated Porous Media

    NASA Astrophysics Data System (ADS)

    Mathieu-Balster, I.; Sicard, J.

    1999-09-01

    Modeling of solute transport in non-saturated and non-isothermal porous media is dealt with by thermodynamics of irreversible processes. This rigorous approach enables us to consider the different kinds of transfer and the coupling. Every physical phenomenon as water phase transition and solute adsorption by the solid matrix can be taken into account. The final model may be applied to several fields such as civil engineering, agronomy, pollution and the assessment of radioactive waste repositories. A numerical modeling taking into account the effect of temperature gradient on solute transport (“Soret effect”) is in the process of implementation in the French software “CESAR-LCPC” of the “Laboratoire Central des Ponts et Chaussées”.

  16. Workshop on Critical Issues in Microgravity Fluids, Transport, and Reaction Processes in Advanced Human Support Technology

    NASA Technical Reports Server (NTRS)

    Chiaramonte, Francis P.; Joshi, Jitendra A.

    2004-01-01

    This workshop was designed to bring the experts from the Advanced Human Support Technologies communities together to identify the most pressing and fruitful areas of research where success hinges on collaborative research between the two communities. Thus an effort was made to bring together experts in both advanced human support technologies and microgravity fluids, transport and reaction processes. Expertise was drawn from academia, national laboratories, and the federal government. The intent was to bring about a thorough exchange of ideas and develop recommendations to address the significant open design and operation issues for human support systems that are affected by fluid physics, transport and reaction processes. This report provides a summary of key discussions, findings, and recommendations.

  17. Mechanisms of transport and exocytosis of dense-core granules containing tissue plasminogen activator in developing hippocampal neurons.

    PubMed

    Silverman, Michael A; Johnson, Scooter; Gurkins, Dmitri; Farmer, Meredith; Lochner, Janis E; Rosa, Patrizia; Scalettar, Bethe A

    2005-03-23

    Dense-core granules (DCGs) are organelles found in specialized secretory cells, including neuroendocrine cells and neurons. Neuronal DCGs facilitate many critical processes, including the transport and secretion of proteins involved in learning, and yet their transport and exocytosis are poorly understood. We have used wide-field and total internal reflection fluorescence microscopy, in conjunction with transport theory, to visualize the transport and exocytosis of DCGs containing a tissue plasminogen activator-green fluorescent protein hybrid in cell bodies, neurites, and growth cones of developing hippocampal neurons and to quantify the roles that diffusion, directed motion, and immobility play in these processes. Our results demonstrate that shorter-ranged transport of DCGs near sites of exocytosis in hippocampal neurons and neuroendocrine cells differs markedly. Specifically, the immobile fraction of DCGs within growth cones and near the plasma membrane of hippocampal neurons is small and relatively unaltered by actin disruption, unlike in neuroendocrine cells. Moreover, transport of DCGs in these domains of hippocampal neurons is unusually heterogeneous, being significantly rapid and directed as well as slow and diffusive. Our results also demonstrate that exocytosis is preceded by substantial movement and heterogeneous transport; this movement may facilitate delivery of DCG cargo in hippocampal neurons, given the relatively low abundance of neuronal DCGs. In addition, the extensive mobility of DCGs in hippocampal neurons argues strongly against the hypothesis that cortical actin is a major barrier to membrane-proximal DCGs in these cells. Instead, our results suggest that extended release of DCG cargo from hippocampal neurons arises from heterogeneity in DCG mobility.

  18. Perceived neighborhood environmental attributes associated with leisure-time and transport physical activity in Mexican adults.

    PubMed

    Jáuregui, Alejandra; Salvo, Deborah; Lamadrid-Figueroa, Héctor; Hernández, Bernardo; Rivera, Juan A; Pratt, Michael

    2016-12-07

    Environmental factors have been associated with specific physical activity domains, including leisure-time and transport physical activity, in some high income countries. Few studies have examined the environmental correlates for domain-specific physical activity in low-and middle-income countries, and results are inconsistent. We aimed to estimate the associations between perceived environment and self-reported leisure-time walking, moderate-to-vigorous leisure-time physical activity and transport physical activity among adults living in Cuernavaca, Mexico. A population-based study of adults 20 to 64years old was conducted in Cuernavaca, Mexico in 2011 (n=677). Leisure and transport physical activity was measured using the International Physical Activity Questionnaire - Long Form. Perceptions of neighborhood environment were obtained by questionnaire. Hurdle regression models estimated the association between environmental perceptions and participation and time spent in each physical activity domain. High perceived aesthetics were positively correlated with participation and time spent in leisure-time walking and moderate-to-vigorous physical activity. SES differences existed for aesthetics in relation to participation in leisure-time walking. Participation in transport physical activity was positively associated with easy access to large parks, while closer distance to large parks was a negative correlate for participation and time-spent in this physical activity domain. Results suggest that perceived environmental characteristics related with physical activity are domain specific. High perceived aesthetics were an important correlate for leisure-time activities among Mexican adults, suggesting that policy strategies aimed at improving this environmental perception may be warranted. Patterns of associations between environmental correlates and transport physical activity differed from those reported in commonly studied high income countries.

  19. Amino-acid transporters in T-cell activation and differentiation.

    PubMed

    Ren, W; Liu, G; Yin, J; Tan, B; Wu, G; Bazer, F W; Peng, Y; Yin, Y

    2017-03-02

    T-cell-mediated immune responses aim to protect mammals against cancers and infections, and are also involved in the pathogenesis of various inflammatory or autoimmune diseases. Cellular uptake and the utilization of nutrients is closely related to the T-cell fate decision and function. Research in this area has yielded surprising findings in the importance of amino-acid transporters for T-cell development, homeostasis, activation, differentiation and memory. In this review, we present current information on amino-acid transporters, such as LAT1 (l-leucine transporter), ASCT2 (l-glutamine transporter) and GAT-1 (γ-aminobutyric acid transporter-1), which are critically important for mediating peripheral naive T-cell homeostasis, activation and differentiation, especially for Th1 and Th17 cells, and even memory T cells. Mechanically, the influence of amino-acid transporters on T-cell fate decision may largely depend on the mechanistic target of rapamycin complex 1 (mTORC1) signaling. These discoveries remarkably demonstrate the role of amino-acid transporters in T-cell fate determination, and strongly indicate that manipulation of the amino-acid transporter-mTORC1 axis could ameliorate many inflammatory or autoimmune diseases associated with T-cell-based immune responses.

  20. Active transportation to school in Canadian youth: should injury be a concern?

    PubMed

    Gropp, Kathleen; Janssen, Ian; Pickett, William

    2013-02-01

    Active transportation to school provides a means for youth to incorporate physical activity into their daily routines, and this has obvious benefits for child health. Studies of active transportation have rarely focused on the negative health effects in terms of injury. This cross-sectional study is based on the 2009/10 Canadian Health Behaviour in School-Aged Children survey. A sample of children aged 11-15 years (n=20 076) was studied. Multi-level logistic regression was used to examine associations between walking or bicycling to school and related injury. Regular active transportation to school at larger distances (approximately >1.6 km; 1.0 miles) was associated with higher relative odds of active transportation injury (OR: 1.52; 95% CI 1.08 to 2.15), with a suggestion of a dose-response relationship between longer travel distances and injury (p=0.02). Physical activity interventions for youth should encourage participation in active transportation to school, while also recognising the potential for unintentional injury.

  1. Laboratory Activities for Developing Process Skills.

    ERIC Educational Resources Information Center

    Institute for Services to Education, Inc., Washington, DC.

    This workbook contains laboratory exercises designed for use in a college introductory biology course. Each exercise helps the student develop a basic science skill. The exercises are arranged in a hierarchical sequence suggesting the scientific method. Each skill facilitates the development of succeeding ones. Activities include Use of the…

  2. Neuronal activity mediated regulation of glutamate transporter GLT‐1 surface diffusion in rat astrocytes in dissociated and slice cultures

    PubMed Central

    Al Awabdh, Sana; Gupta‐Agarwal, Swati; Sheehan, David F.; Muir, James; Norkett, Rosalind; Twelvetrees, Alison E.; Griffin, Lewis D.

    2016-01-01

    The astrocytic GLT‐1 (or EAAT2) is the major glutamate transporter for clearing synaptic glutamate. While the diffusion dynamics of neurotransmitter receptors at the neuronal surface are well understood, far less is known regarding the surface trafficking of transporters in subcellular domains of the astrocyte membrane. Here, we have used live‐cell imaging to study the mechanisms regulating GLT‐1 surface diffusion in astrocytes in dissociated and brain slice cultures. Using GFP‐time lapse imaging, we show that GLT‐1 forms stable clusters that are dispersed rapidly and reversibly upon glutamate treatment in a transporter activity‐dependent manner. Fluorescence recovery after photobleaching and single particle tracking using quantum dots revealed that clustered GLT‐1 is more stable than diffuse GLT‐1 and that glutamate increases GLT‐1 surface diffusion in the astrocyte membrane. Interestingly, the two main GLT‐1 isoforms expressed in the brain, GLT‐1a and GLT‐1b, are both found to be stabilized opposed to synapses under basal conditions, with GLT‐1b more so. GLT‐1 surface mobility is increased in proximity to activated synapses and alterations of neuronal activity can bidirectionally modulate the dynamics of both GLT‐1 isoforms. Altogether, these data reveal that astrocytic GLT‐1 surface mobility, via its transport activity, is modulated during neuronal firing, which may be a key process for shaping glutamate clearance and glutamatergic synaptic transmission. GLIA 2016;64:1252–1264 PMID:27189737

  3. Coupling biological processes and gaseous transport in models describing GHG emission from soils

    NASA Astrophysics Data System (ADS)

    Blagodatsky, S.; Smith, P.

    2012-04-01

    The precise coupling of gaseous transport and biochemistry in models describing the emission of greenhouse gases (GHG) from soil is necessary because CH4 and N2O can be both produced and consumed in soil. Eventual fluxes to the atmosphere depends on the position of reaction sites and the escape pathways for these gases. The CO2 production rate depends in turn on the efficiency of oxygen transport in the soil. Basing on models published in literature and our own experience the main principles leading to the best simulation results can be summarized as: 1) keeping a balanced level of detail in coupled model systems describing biochemical reactions and transport; 2) reduction of unnecessary complexity by means of using the most essential relationships elucidated by comprehensive statistical model testing; 3) consideration of all transport mechanisms in relation to prevailing ecological conditions. We will show examples of the successful application of coupled model systems for the prediction of three main GHG: CO2, N2O and CH4 as well as results of application of our model MICNIT designed for the simulation of CO2 and N2O emission and microbial C and N turnover in soil. We conclude that coupled gas transport and decomposition models lack the latest findings in modelling microbial growth in soil. So, models including an explicit description of microbial growth, i.e. growth rate and efficiency, humification ratios and their relationship with N availability (Blagodatsky, Richter, 1998; Moorhead and Sinsabaugh, 2006; Eliasson, and Ågren, 2011) need to be coupled with well-developed soil physics models with appropriate description of transport processes.

  4. Hydrologic Processes Controlling the Transport of Radionuclides Through the Hanford Vadose Zone

    NASA Astrophysics Data System (ADS)

    Mayes, M. A.; Jardine, P. M.; Pace, M. N.; Fendorf, S. E.; Mehlhorn, T. L.; Roh, Y.; Ladd, J. L.; Bjornstad, B. N.

    2001-12-01

    At the U.S. Department of Energy's Hanford Reservation in south central Washington, accelerated migration of radionuclides has been observed in the vadose zone beneath the Hanford Tank Farms. The goal of this research was to provide an improved understanding and predictive capability of the coupled hydrological and geochemical mechanisms that are responsible for contaminant mobility in the vadose zone. The research strategy consisted of collecting undisturbed sediment cores (0.3 m diameter x 0.3 m length) in order to perform laboratory-scale, multiple nonreactive and reactive transport experiments at a variety of different water contents. Cores were collected from the Miocene-Pliocene age Upper Ringold Formation, which consists of fine sand, silt and clay. Cores were acquired both parallel and perpendicular to bedding. Two units within the U. Ringold were sampled, a horizontally-bedded, laminated Upper Silt and a cross-bedded Lower Silty Sand. Unsaturated transport experiments were performed using the nonreactive tracers Br-, PFBA, and PIPES, which differ in their free-water molecular diffusion coefficients. Unsaturated transport experiments through cores with discontinuous layering resulted in the formation of an unstable wetting front characterized by preferential finger flow and the development of zones of perched water. Media bypass is inferred by early breakthrough of tracers relative to saturated flow, while the presence of perched water is suggested by decreasing core matric potential. Further, observed separation of tracers (Br-> PFBA > PIPES) suggests that diffusional processes can contribute to contaminant transport. Conversely, transport through cores composed of laterally continuous beds did not result in preferential flow, the development of perched water, or tracer separation regardless of saturation. This suggests a propensity for lateral flow beneath the tank farms. Preferential vertical finger flow may be initiated by intersection with lithologic

  5. Research on numerical simulation and protection of transient process in long-distance slurry transportation pipelines

    NASA Astrophysics Data System (ADS)

    Lan, G.; Jiang, J.; Li, D. D.; Yi, W. S.; Zhao, Z.; Nie, L. N.

    2013-12-01

    The calculation of water-hammer pressure phenomenon of single-phase liquid is already more mature for a pipeline of uniform characteristics, but less research has addressed the calculation of slurry water hammer pressure in complex pipelines with slurry flows carrying solid particles. In this paper, based on the developments of slurry pipelines at home and abroad, the fundamental principle and method of numerical simulation of transient processes are presented, and several boundary conditions are given. Through the numerical simulation and analysis of transient processes of a practical engineering of long-distance slurry transportation pipeline system, effective protection measures and operating suggestions are presented. A model for calculating the water impact of solid and fluid phases is established based on a practical engineering of long-distance slurry pipeline transportation system. After performing a numerical simulation of the transient process, analyzing and comparing the results, effective protection measures and operating advice are recommended, which has guiding significance to the design and operating management of practical engineering of longdistance slurry pipeline transportation system.

  6. Activity-dependent transport of GABA analogues into specific cell types demonstrated at high resolution using a novel immunocytochemical strategy.

    PubMed

    Pow, D V; Baldridge, W; Crook, D K

    1996-08-01

    We have raised antisera against the GABA analogues gamma-vinyl GABA, diaminobutyric acid and gabaculine. These analogues are thought to be substrates for high-affinity GABA transporters. Retinae were exposed to micromolar concentrations of these analogues in the presence or absence of uptake inhibitors and then fixed and processed for immunocytochemistry at the light and electron microscopic levels. Immunolabelling for gamma-vinyl GABA revealed specific labelling of GABAergic amacrine cells and displaced amacrine cells in retinae of rabbits, cats, chickens, fish and a monkey. GABA-containing horizontal cells of cat and monkey retinae failed to exhibit labelling for gamma-vinyl GABA, suggesting that they lacked an uptake system for this molecule. In light-adapted fish, gamma-vinyl GABA was readily detected in H1 horizontal cells; similar labelling was also observed in light-adapted chicken retinae. The pattern of labelling in the fish and chicken retinae was modified by dark adaptation, when labelling was greatly reduced in the horizontal cells, indicating the activity dependence of GABA (analogue) transport. Intraperitoneal injection of gamma-vinyl GABA into rats resulted in its transport across the blood-brain barrier and subsequent uptake into populations of GABAergic neurons. The other analogues investigated in this study exhibited different patterns of transport; gabaculine was taken up into glial cells, whilst diaminobutyric acid was taken up into neurons, glial cells and retinal pigment epithelia. Thus, these analogues are probably substrates for different GABA transporters. We conclude that immunocytochemical detection of the high-affinity uptake of gamma-vinyl GABA permits the identification of GABAergic neurons which are actively transporting GABA, and suggest that this novel methodology will be a useful tool in rapidly assessing the recent activity of GABAergic neurons at the cellular level.

  7. Extracellular nucleotides inhibit oxalate transport by human intestinal Caco-2-BBe cells through PKC-δ activation.

    PubMed

    Amin, Ruhul; Sharma, Sapna; Ratakonda, Sireesha; Hassan, Hatim A

    2013-07-01

    Nephrolithiasis remains a major health problem in Western countries. Seventy to 80% of kidney stones are composed of calcium oxalate, and small changes in urinary oxalate affect risk of kidney stone formation. Intestinal oxalate secretion mediated by the anion exchanger SLC26A6 plays an essential role in preventing hyperoxaluria and calcium oxalate nephrolithiasis, indicating that understanding the mechanisms regulating intestinal oxalate transport is critical for management of hyperoxaluria. Purinergic signaling modulates several intestinal processes through pathways including PKC activation, which we previously found to inhibit Slc26a6 activity in mouse duodenal tissue. We therefore examined whether purinergic stimulation with ATP and UTP affects oxalate transport by human intestinal Caco-2-BBe (C2) cells. We measured [¹⁴C]oxalate uptake in the presence of an outward Cl⁻ gradient as an assay of Cl⁻/oxalate exchange activity, ≥50% of which is mediated by SLC26A6. We found that ATP and UTP significantly inhibited oxalate transport by C2 cells, an effect blocked by the PKC inhibitor Gö-6983. Utilizing pharmacological agonists and antagonists, as well as PKC-δ knockdown studies, we observed that ATP inhibits oxalate transport through the P2Y₂ receptor, PLC, and PKC-δ. Biotinylation studies showed that ATP inhibits oxalate transport by lowering SLC26A6 surface expression. These findings are of potential relevance to pathophysiology of inflammatory bowel disease-associated hyperoxaluria, where supraphysiological levels of ATP/UTP are expected and overexpression of the P2Y₂ receptor has been reported. We conclude that ATP and UTP inhibit oxalate transport by lowering SLC26A6 surface expression in C2 cells through signaling pathways including the P2Y₂ purinergic receptor, PLC, and PKC-δ.

  8. Modelling the Active Hearing Process in Mosquitoes

    NASA Astrophysics Data System (ADS)

    Avitabile, Daniele; Homer, Martin; Jackson, Joe; Robert, Daniel; Champneys, Alan

    2011-11-01

    A simple microscopic mechanistic model is described of the active amplification within the Johnston's organ of the mosquito species Toxorhynchites brevipalpis. The model is based on the description of the antenna as a forced-damped oscillator coupled to a set of active threads (ensembles of scolopidia) that provide an impulsive force when they twitch. This twitching is in turn controlled by channels that are opened and closed if the antennal oscillation reaches a critical amplitude. The model matches both qualitatively and quantitatively with recent experiments. New results are presented using mathematical homogenization techniques to derive a mesoscopic model as a simple oscillator with nonlinear force and damping characteristics. It is shown how the results from this new model closely resemble those from the microscopic model as the number of threads approach physiologically correct values.

  9. Heat Transfer Processes for the Thermal Energy Balance of Organisms. Physical Processes in Terrestrial and Aquatic Ecosystems, Transport Processes.

    ERIC Educational Resources Information Center

    Stevenson, R. D.

    This module is part of a series designed to be used by life science students for instruction in the application of physical theory to ecosystem operation. Most modules contain computer programs which are built around a particular application of a physical process. This module describes heat transfer processes involved in the exchange of heat…

  10. Capturing Cognitive Processing Time for Active Authentication

    DTIC Science & Technology

    2014-02-01

    biometrics, extracted from keystroke dynamics , as “something a user is” for active authentication. This scheme performs continual verification in the...fingerprint for continuous authentication. Its effectiveness has been verified through a large-scale dataset. 2.0 INTRODUCTION Keystroke dynamics —the...measure the similarity. A recent survey on biometric authentication using keystroke dynamics classified research papers on the basis of their

  11. Regulation of Human Hepatic Drug Transporter Activity and Expression by Diesel Exhaust Particle Extract

    PubMed Central

    Le Vee, Marc; Jouan, Elodie; Stieger, Bruno; Lecureur, Valérie; Fardel, Olivier

    2015-01-01

    Diesel exhaust particles (DEPs) are common environmental air pollutants primarily affecting the lung. DEPs or chemicals adsorbed on DEPs also exert extra-pulmonary effects, including alteration of hepatic drug detoxifying enzyme expression. The present study was designed to determine whether organic DEP extract (DEPe) may target hepatic drug transporters that contribute in a major way to drug detoxification. Using primary human hepatocytes and transporter-overexpressing cells, DEPe was first shown to strongly inhibit activities of the sinusoidal solute carrier (SLC) uptake transporters organic anion-transporting polypeptides (OATP) 1B1, 1B3 and 2B1 and of the canalicular ATP-binding cassette (ABC) efflux pump multidrug resistance-associated protein 2, with IC50 values ranging from approximately 1 to 20 μg/mL and relevant to environmental exposure situations. By contrast, 25 μg/mL DEPe failed to alter activities of the SLC transporter organic cation transporter (OCT) 1 and of the ABC efflux pumps P-glycoprotein and bile salt export pump (BSEP), whereas it only moderately inhibited those of sodium taurocholate co-transporting polypeptide and of breast cancer resistance protein (BCRP). Treatment by 25 μg/mL DEPe was next demonstrated to induce expression of BCRP at both mRNA and protein level in cultured human hepatic cells, whereas it concomitantly repressed mRNA expression of various transporters, including OATP1B3, OATP2B1, OCT1 and BSEP. Such changes in transporter expression were found to be highly correlated to those caused by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a reference activator of the aryl hydrocarbon receptor (AhR) pathway. This suggests that DEPe, which is enriched in known ligands of AhR like polycyclic aromatic hydrocarbons, alters drug transporter expression via activation of the AhR cascade. Taken together, these data established human hepatic transporters as targets of organic chemicals containing in DEPs, which may contribute to their

  12. The association between green neighborhood environments and active transportation

    EPA Science Inventory

    Background: Urban nature is an important aspect of health-promoting environments. In particular, street trees and green space can provide a low cost approach to improving public health by promoting physical activity, improving mental health, and facilitating social cohesion. Acti...

  13. Local momentum and heat fluxes in transient transport processes and inhomogeneous systems.

    PubMed

    Chen, Youping; Diaz, Adrian

    2016-11-01

    This work examines existing formalisms for the derivation of microscopic momentum and heat fluxes. Both analytical and simulation results are provided to show that the widely used flux formulas are not applicable to transient transport processes or highly inhomogeneous systems, e.g., materials with atomically sharp interfaces. A method is formulated for formally deriving microscopic momentum and heat fluxes through the integral representation of conservation laws. The resulting flux formulas are mathematically rigorous, fully consistent with the physical concepts of momentum and heat fluxes, and applicable to nonequilibrium transient processes in atomically inhomogeneous systems with general many-body forces.

  14. Local momentum and heat fluxes in transient transport processes and inhomogeneous systems

    NASA Astrophysics Data System (ADS)

    Chen, Youping; Diaz, Adrian

    2016-11-01

    This work examines existing formalisms for the derivation of microscopic momentum and heat fluxes. Both analytical and simulation results are provided to show that the widely used flux formulas are not applicable to transient transport processes or highly inhomogeneous systems, e.g., materials with atomically sharp interfaces. A method is formulated for formally deriving microscopic momentum and heat fluxes through the integral representation of conservation laws. The resulting flux formulas are mathematically rigorous, fully consistent with the physical concepts of momentum and heat fluxes, and applicable to nonequilibrium transient processes in atomically inhomogeneous systems with general many-body forces.

  15. Red blood cell cation transports in uraemic anaemia: evidence for an increased K/Cl co-transport activity. Effects of dialysis and erythropoietin treatment.

    PubMed

    De Franceschi, L; Olivieri, O; Girelli, D; Lupo, A; Bernich, P; Corrocher, R

    1995-10-01

    This study examines the role of uraemia and the effect of different dialysis treatments on red cell cation transport. We evaluated the main cation transport systems in erythrocytes of non-dialysed end-stage renal disease (ESRD) subjects, of patients undergoing haemodialysis (HD) and continuous ambulatory peritoneal dialysis (CAPD), as well as the changes induced by human recombinant erythropoietin (r-HuEPO) administration. In uraemic undialysed and dialysed patients, we observed an increase in K/Cl co-transport activity and in shrinkage-induced amiloride-sensitive (HMA-sensitive) Na efflux (Na/H exchange) and a decrease in Na/K pump and Na/K/Cl co-transport activity, while Na/Li exchange was increased only in dialysed patients. In uraemic erythrocytes, we showed for the first time an increased K/Cl co-transport activity, which was cell age independent. Generally, the different method of dialysis (CAPD or HD) did not modify the cation transport abnormalities observed. During the treatment with r-HuEPO, all the systems, with the exception of the Na/K pump and Na/K/Cl co-transport, increased their activities following the increase of circulating young red cells. The changes produced under r-HuEPO administration were transient and cation transports returned to the baseline values within 100 days of treatment, indicating a primary and prominent pathogenetic role of uraemia in modulating the red cell membrane cation transport activities.

  16. Nutritional impact of elevated calcium transport activity in carrots

    PubMed Central

    Morris, Jay; Hawthorne, Keli M.; Hotze, Tim; Abrams, Steven A.; Hirschi, Kendal D.

    2008-01-01

    Nutrition recommendations worldwide emphasize ingestion of plant-based diets rather than diets that rely primarily on animal products. However, this plant-based diet could limit the intake of essential nutrients such as calcium. Osteoporosis is one of the world's most prevalent nutritional disorders, and inadequate dietary calcium is a known contributor to the pathophysiology of this condition. Previously, we have modified carrots to express increased levels of a plant calcium transporter (sCAX1), and these plants contain ≈2-fold-higher calcium content in the edible portions of the carrots. However, it was unproven whether this change would increase the total amount of bioavailable calcium. In randomized trials, we labeled these modified carrots with isotopic calcium and fed them to mice and humans to assess calcium bioavailability. In mice feeding regimes (n = 120), we measured 45Ca incorporation into bones and determined that mice required twice the serving size of control carrots to obtain the calcium found in sCAX1 carrots. We used a dual-stable isotope method with 42Ca-labeled carrots and i.v. 46Ca to determine the absorption of calcium from these carrots in humans. In a cross-over study of 15 male and 15 female adults, we found that when people were fed sCAX1 and control carrots, total calcium absorption per 100 g of carrots was 41% ± 2% higher in sCAX1 carrots. Both the mice and human feeding studies demonstrate increased calcium absorption from sCAX1-expressing carrots compared with controls. These results demonstrate an alternative means of fortifying vegetables with bioavailable calcium. PMID:18202180

  17. Thyroid-induced alterations in myocardial sodium-potassium-activated adenosine triphosphatase, monovalent cation active transport, and cardiac glycoside binding.

    PubMed Central

    Curfman, G D; Crowley, T J; Smith, T W

    1977-01-01

    The effects of thyroid hormone on guinea pig myocardial NaK-ATPase activity, transmembrane monovalent cation active transport, and cardiac glycoside binding were were examined. NaK-ATPase activities of left atrial and left ventricular homogenates of control and triiodothyronine (T3)-treated animals were determined, and compared to activities of skeletal muscle and liver. T3 administration was associated with a significant increase of 18% in left atrial and left ventricular NaK-ATPase specific activities. This increment was less than that noted in skeletal muscle (+42%) and liver (+30%). To determine if enhanced NaK-ATPase activity was accompanied by increased monovalent cation active transport, in vitro 86Rb+ uptake by left atrial strips and hemidiaphragms was measured. Transition from the euthyroid to the hyperthyroid state resulted in a 68% increase in active 86Rb+ uptake by left atrium, and a 62% increase in active uptake by diaphragm. Passive 86Rb+ uptake was not affected in either tissue. Ouabain binding by atrial and ventricular homogenates of T3-treated animals was increased by 19 and 17%, respectively, compared to controls, in close agreement with thyroid-induced increments in NaK-ATPase activiey. Taken together, these results are consistent with enhanced myocardial NaK-ATPase activity and monovalent cation activt transport due to an increase in the number of functional enzyme complexes. PMID:138689

  18. A Coupling Kinetics Model for Pollutant Release and Transport in the Process of Landfill Settlement

    PubMed Central

    Zhao, Ying; Xue, Qiang; Liu, Lei

    2012-01-01

    A coupling kinetics model is developed to simulate the release and transport of landfill leachate pollutants in a deformable municipal solid waste landfill by taking into account of landfill settlement, seepage of leachate water, hydrolyse of insoluble and degradable organic pollutants in solid phase, biodegradation of soluble and degradable organic pollutants in solid phase and aqueous one, growth of aerobic and anaerobic microorganism, and consumption of dissolved oxygen. The release and transport of organic pollutants and microorganisms in landfills in the process of landfill settlement was simulated by considering no hydraulic effect. Simulation results demonstrated that the interaction between landfill settlement and the release, transport and biodegradation of landfill leachate pollutants was significant. Porosity and saturated hydraulic conductivity were not constants because of the landfill settlement, which affected the release, transport and biodegradation of landfill leachate pollutants, and furthermore acted on the landfill settlement. The simulation results accorded with the practical situation, which preliminarily verified the reliability of the mathematical model and the numerical program in this paper. PMID:23202755

  19. A coupling kinetics model for pollutant release and transport in the process of landfill settlement.

    PubMed

    Zhao, Ying; Xue, Qiang; Liu, Lei

    2012-09-27

    A coupling kinetics model is developed to simulate the release and transport of landfill leachate pollutants in a deformable municipal solid waste landfill by taking into account of landfill settlement, seepage of leachate water, hydrolyse of insoluble and degradable organic pollutants in solid phase, biodegradation of soluble and degradable organic pollutants in solid phase and aqueous one, growth of aerobic and anaerobic microorganism, and consumption of dissolved oxygen. The release and transport of organic pollutants and microorganisms in landfills in the process of landfill settlement was simulated by considering no hydraulic effect. Simulation results demonstrated that the interaction between landfill settlement and the release, transport and biodegradation of landfill leachate pollutants was significant. Porosity and saturated hydraulic conductivity were not constants because of the landfill settlement, which affected the release, transport and biodegradation of landfill leachate pollutants, and furthermore acted on the landfill settlement. The simulation results accorded with the practical situation, which preliminarily verified the reliability of the mathematical model and the numerical program in this paper.

  20. Intracellular transport and processing of a tobacco vacuolar β-1,3-glucanase.

    PubMed

    Sticher, L; Hinz, U; Meyer, A D; Meins, F

    1992-11-01

    The class I β-1,3-glucanases are basic, vacuolar enzymes implicated in the defense of plants against pathogen infection. The tobacco (Nicotiana tabacum L.) enzyme is synthesized as a preproprotein with an N-terminal signal peptide for targeting to the lumen of the endoplasmic reticulum and an N-glycosylated C-terminal extension which is lost during protein maturation. The transport and processing of β-1,3-glucanase in cellsuspension cultures of the tobacco cultivar Havana 425 was investigated by pulse-chase labelling and cell fractionation. We verified that mature β-1,3-glucanase is localized in the vacuole of the suspension-cultured cells. Comparison of the time course of processing in homogenates, the soluble fraction, and membrane fractions indicates that proglucanase is transported from the endoplasmic reticulum via the Golgi compartment to the vacuole. Processing to the mature form occurs in the vacuole. Treatment of cells with tunicamycin, which inhibits N-glycosylation, and digestion of the (35)S-labelled processing intermediates with endoglycosidase H indicate that β-1,3-glucanase has a single N-glycan attached to the C-terminal extension. Glycosylation is not required for proteolytic processing or correct targeting to the vacuole.

  1. Uav Data Processing for Rapid Mapping Activities

    NASA Astrophysics Data System (ADS)

    Tampubolon, W.; Reinhardt, W.

    2015-08-01

    During disaster and emergency situations, geospatial data plays an important role to serve as a framework for decision support system. As one component of basic geospatial data, large scale topographical maps are mandatory in order to enable geospatial analysis within quite a number of societal challenges. The increasing role of geo-information in disaster management nowadays consequently needs to include geospatial aspects on its analysis. Therefore different geospatial datasets can be combined in order to produce reliable geospatial analysis especially in the context of disaster preparedness and emergency response. A very well-known issue in this context is the fast delivery of geospatial relevant data which is expressed by the term "Rapid Mapping". Unmanned Aerial Vehicle (UAV) is the rising geospatial data platform nowadays that can be attractive for modelling and monitoring the disaster area with a low cost and timely acquisition in such critical period of time. Disaster-related object extraction is of special interest for many applications. In this paper, UAV-borne data has been used for supporting rapid mapping activities in combination with high resolution airborne Interferometric Synthetic Aperture Radar (IFSAR) data. A real disaster instance from 2013 in conjunction with Mount Sinabung eruption, Northern Sumatra, Indonesia, is used as the benchmark test for the rapid mapping activities presented in this paper. On this context, the reliable IFSAR dataset from airborne data acquisition in 2011 has been used as a comparable dataset for accuracy investigation and assessment purpose in 3 D reconstructions. After all, this paper presents a proper geo-referencing and feature extraction method of UAV data to support rapid mapping activities.

  2. Transport processes and distribution of plasma in the ionosphere during total solar eclipses

    NASA Astrophysics Data System (ADS)

    Chukwuma, Victor

    2016-07-01

    The effect of solar eclipse on the ionospheric F2 layer does not appear to depend only on the changes in the electron density. In this regards therefore, we have investigated the transport term process and the distribution F2 plasma during three total solar eclipses (TSE) at low- and mid-latitude. Particularly, the diurnal changes in the NmF2 and hmF2 during these spectacular events, as recorded by the ionosondes situated along the path of solar eclipses, which are within the obscuration percentage of 59-90% were investigated. Presently, our results show that NmF2 decreased during the eclipse window, as a consequence of the variation in the local solar radiation in regions under investigation. However, at mid-latitude, the distribution of F2 plasma was dominated by diffusion mechanisms which determined the height at which the F2 peak formed and were related to the changes in thermospheric composition. While at low-latitude the plasma distribution during TSE appeared to depend on combined effect of solar ionizing radiation (SIR) and the background nighttime ionospheric instabilities/irregularities mechanism. The downward/upward transport processes of the plasma appear to correspond with the drifting of the diffusion mechanisms and suffered a comparable variation with the SIR. Furthermore, at low-latitude ionosphere the transport process is controlled by the equatorial electric field. It is also observed that the eastward/westward movement of the equatorial electric field during the eclipse phase was connected to the upward/downward movement of the vertical transport. In conclusion, our results appear to indicate that eclipse effects increased with increase in latitude and the time lag decreases with increase in latitude.

  3. High liquid fuel yielding biofuel processes and a roadmap for the future transportation

    NASA Astrophysics Data System (ADS)

    Singh, Navneet R.

    In a fossil-fuel deprived world when crude oil will be scarce and transportation need cannot be met with electricity and transportation liquid fuel must be produced, biomass derived liquid fuels can be a natural replacement. However, the carbon efficiency of the currently known biomass to liquid fuel conversion processes ranges from 35-40%, yielding 90 ethanol gallon equivalents (ege) per ton of biomass. This coupled with the fact that the efficiency at which solar energy is captured by biomass (<1%) is significantly lower than H 2 (10-27%) and electricity (20-42%), implies that sufficient land area is not available to meet the need for the entire transportation sector. To counter this dilemma, a number of processes have been proposed in this work: a hybrid hydrogen-carbon (H2CAR) process based on biomass gasification followed by the Fischer-Tropsch process such that 100% carbon efficiency is achieved yielding 330 ege/ton biomass using hydrogen derived from a carbon-free energy. The hydrogen requirement for the H2CAR process is 0.33 kg/liter of diesel. To decrease the hydrogen requirement associated with the H2CAR process, a hydrogen bio-oil (H2Bioil) process based on biomass fast-hydropyrolysis/hydrodeoxygenation is proposed which can achieve liquid fuel yield of 215 ege/ton consuming 0.11 kg hydrogen per liter of oil. Due to the lower hydrogen consumption of the H2Bioil process, synergistically integrated transition pathways are feasible where hot syngas derived from coal gasification (H2Bioil-C) or a natural gas reformer (H 2Bioil-NG) is used to supply the hydrogen and process heat for the biomass fast-hydropyrolysis/hydrodeoxygenation. Another off-shoot of the H2Bioil process is the H2Bioil-B process, where hydrogen required for the hydropyrolysis is obtained from gasification of a fraction of the biomass. H2Bioil-B achieves the highest liquid fuel yield (126-146 ege/ton of biomass) reported in the literature for any self-contained conversion of biomass to

  4. Metronidazole activation and isolation of Clostridium acetobutylicum electron transport genes.

    PubMed Central

    Santangelo, J D; Jones, D T; Woods, D R

    1991-01-01

    An Escherichia coli F19 recA, nitrate reductase-deficient mutant was constructed by transposon mutagenesis and shown to be resistant to metronidazole. This mutant was a most suitable host for the isolation of Clostridium acetobutylicum genes on recombinant plasmids, which activated metronidazole and rendered the E. coli F19 strain sensitive to metronidazole. Twenty-five E. coli F19 clones containing different recombinant plasmids were isolated and classified into five groups on the basis of their sensitivity to metronidazole. The clones were tested for nitrate reductase, pyruvate-ferredoxin oxidoreductase, and hydrogenase activities. DNA hybridization and restriction endonuclease mapping revealed that four of the C. acetobutylicum insert DNA fragments on recombinant plasmids were linked in an 11.1-kb chromosomal fragment. DNA sequencing and amino acid homology studies indicated that this DNA fragment contained a flavodoxin gene which encoded a protein of 160 amino acids that activated metronidazole and made the E. coli F19 mutant very sensitive to metronidazole. The flavodoxin and hydrogenase genes which are involved in electron transfer systems were linked on the 11.1-kb DNA fragment from C. acetobutylicum. Images PMID:1991710

  5. The co-benefits for health of investing in active transportation.

    PubMed

    Giles-Corti, Billie; Foster, Sarah; Shilton, Trevor; Falconer, Ryan

    2010-01-01

    Amid growing concerns about the impact of rising obesity and physical inactivity levels, climate change, population growth, increasing traffic congestion and declining oil supplies, multiple sectors are now promoting active transportation as an alternative to driving. This paper considers the health benefits and co-benefits of investing in active transportation, enabling comparison of policy options to optimise societal objectives aimed at creating healthy, socially and environmentally sustainable communities. Policies promoting the use of both energy-efficient motor vehicles and increased active transportation would almost double the impact on greenhouse gas emissions and would reduce disease burden by increasing physical activity. More co-benefit and economic analyses research is required to inform 'joined-up' policy solutions.

  6. Processing abstract language modulates motor system activity.

    PubMed

    Glenberg, Arthur M; Sato, Marc; Cattaneo, Luigi; Riggio, Lucia; Palumbo, Daniele; Buccino, Giovanni

    2008-06-01

    Embodiment theory proposes that neural systems for perception and action are also engaged during language comprehension. Previous neuroimaging and neurophysiological studies have only been able to demonstrate modulation of action systems during comprehension of concrete language. We provide neurophysiological evidence for modulation of motor system activity during the comprehension of both concrete and abstract language. In Experiment 1, when the described direction of object transfer or information transfer (e.g., away from the reader to another) matched the literal direction of a hand movement used to make a response, speed of responding was faster than when the two directions mismatched (an action-sentence compatibility effect). In Experiment 2, we used single-pulse transcranial magnetic stimulation to study changes in the corticospinal motor pathways to hand muscles while reading the same sentences. Relative to sentences that do not describe transfer, there is greater modulation of activity in the hand muscles when reading sentences describing transfer of both concrete objects and abstract information. These findings are discussed in relation to the human mirror neuron system.

  7. Policies Related to Active Transport to and from School: A Multisite Case Study

    ERIC Educational Resources Information Center

    Eyler, Amy A.; Brownson, Ross C.; Doescher, Mark P.; Evenson, Kelly R.; Fesperman, Carrie E.; Litt, Jill S.; Pluto, Delores; Steinman, Lesley E.; Terpstra, Jennifer L.; Troped, Philip J.; Schmid, Thomas L.

    2008-01-01

    Active transportation to and from school (ATS) is a viable strategy to help increase physical activity among youth. ATS can be challenging because initiatives require transdisciplinary collaboration, are influenced by the built environment and are affected by numerous policies. The purpose of this study is to identify policies and factors that…

  8. The Effect of an Active Transport to School Intervention at a Suburban Elementary School

    ERIC Educational Resources Information Center

    Bungum, Timothy J.; Clark, Sheila; Aguilar, Brenda

    2014-01-01

    Background: Many children do not meet physical activity (PA) guidelines. One strategy that may enhance PA is to increase active transport to school (ATS) rates. Purpose: To assess the effects of an ATS intervention. Methods: A quasi-experimental design was used to compare ATS and vehicle traffic rates at a school that participated in a statewide…

  9. Revealing the flux: Using processed Husimi maps to visualize dynamics of bound systems and mesoscopic transport

    NASA Astrophysics Data System (ADS)

    Mason, Douglas J.; Borunda, Mario F.; Heller, Eric J.

    2015-04-01

    We elaborate upon the "processed Husimi map" representation for visualizing quantum wave functions using coherent states as a measurement of the local phase space to produce a vector field related to the probability flux. Adapted from the Husimi projection, the processed Husimi map is mathematically related to the flux operator under certain limits but offers a robust and flexible alternative since it can operate away from these limits and in systems that exhibit zero flux. The processed Husimi map is further capable of revealing the full classical dynamics underlying a quantum wave function since it reverse engineers the wave function to yield the underlying classical ray structure. We demonstrate the capabilities of processed Husimi maps on bound systems with and without electromagnetic fields, as well as on open systems on and off resonance, to examine the relationship between closed system eigenstates and mesoscopic transport.

  10. Experimental investigation on the role of bacterial growth and bacterial transport in MEOR processes

    SciTech Connect

    Jang, L.K.; Yen, T.F.

    1983-03-01

    In order to define the dynamics of Microbial Enhanced Oil Recovery (MEOR) process bench-scale MEOR using Bacillus subtilis was undertaken. The relationship between bacterial transport in the oil containing porous media, growth rate and the efficiency of oil recovery was investigated. Work using Pseudomonas fluorescens and clostridium acetobutylicum is in progress (no data). Heavy crude (API gravity 17/sup 0/) was used in these studies in which Continuous Flooding Process and the combination Huff-and-Puff and Nutrient Flooding Processes were compared. B. subtilis provided greater than 40% oil recovery after secondary flooding. Growth is satisfactory provided adequate nutrient and oxygen supply. Liquid phase metabolites (polysaccharides, lipids) and gaseous phase metabolites (CO/sub 2/, etc.) improve recovery. The Huff-and-Puff, etc. combination process is the most efficient based on nutrient consumption.

  11. Prolactin increases hepatic Na+/taurocholate co-transport activity and messenger RNA post partum.

    PubMed Central

    Ganguly, T C; Liu, Y; Hyde, J F; Hagenbuch, B; Meier, P J; Vore, M

    1994-01-01

    We have shown that Na+/taurocholate co-transport activity is decreased in pregnancy, but rebounds post partum relative to non-pregnant controls, and that activity can be increased by treatment with ovine prolactin [Ganguly, Hyde and Vore (1993) J. Pharmacol. Exp. Ther. 267, 82-87]. To determine the basis for these effects, Na+/taurocholate co-transport was determined in purified basolateral liver plasma-membrane (bLPM) vesicles and compared with steady-state mRNA levels encoding the Na+/taurocholate-co-transporting polypeptide (Ntcp) in non-pregnant controls, pregnant rats (19-20 days pregnant), rats post partum (48 h post partum) and rats post partum treated with bromocriptine to inhibit prolactin secretion. Na+/taurocholate co-transport activity (nmol/5 s per mg of protein) in bLPM was decreased from 10.4 +/- 1.8 in non-pregnant controls to 7.9 +/- 0.6 in bLPM in pregnant rats, but rebounded to 17.5 +/- 1.3 post partum; treatment of rats post partum with bromocriptine to inhibit prolactin secretion decreased activity to 14.1 +/- 0.9. Northern and slot-blot analyses revealed similar changes in mRNA for Ntcp, so that a positive correlation was observed between Na+/taurocholate co-transport activity and Ntcp mRNA. Furthermore, treatment of ovariectomized rats with ovine prolactin increased Ntcp mRNA 10-fold compared with solvent-treated controls, consistent with the 2-fold increase in Vmax, for Na+/taurocholate co-transport in isolated hepatocytes. These data are the first to demonstrate endogenous physiological regulation by prolactin of Ntcp mRNA in parallel with Na+/taurocholate co-transport activity. Images Figure 2 PMID:7945260

  12. Built Environment and Active Transport to School (BEATS) Study: protocol for a cross-sectional study

    PubMed Central

    Mandic, Sandra; Williams, John; Moore, Antoni; Hopkins, Debbie; Flaherty, Charlotte; Wilson, Gordon; García Bengoechea, Enrique; Spence, John C

    2016-01-01

    Introduction Active transport to school (ATS) is a convenient way to increase physical activity and undertake an environmentally sustainable travel practice. The Built Environment and Active Transport to School (BEATS) Study examines ATS in adolescents in Dunedin, New Zealand, using ecological models for active transport that account for individual, social, environmental and policy factors. The study objectives are to: (1) understand the reasons behind adolescents and their parents' choice of transport mode to school; (2) examine the interaction between the transport choices, built environment, physical activity and weight status in adolescents; and (3) identify policies that promote or hinder ATS in adolescents. Methods and analysis The study will use a mixed-method approach incorporating both quantitative (surveys, anthropometry, accelerometers, Geographic Information System (GIS) analysis, mapping) and qualitative methods (focus groups, interviews) to gather data from students, parents, teachers and school principals. The core data will include accelerometer-measured physical activity, anthropometry, GIS measures of the built environment and the use of maps indicating route to school (students)/work (parents) and perceived safe/unsafe areas along the route. To provide comprehensive data for understanding how to change the infrastructure to support ATS, the study will also examine complementary variables such as individual, family and social factors, including student and parental perceptions of walking and cycling to school, parental perceptions of different modes of transport to school, perceptions of the neighbourhood environment, route to school (students)/work (parents), perceptions of driving, use of information communication technology, reasons for choosing a particular school and student and parental physical activity habits, screen time and weight status. The study has achieved a 100% school recruitment rate (12 secondary schools). Ethics and

  13. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-10-07

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  14. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, Gifford G.; Kato, Takeo R.; Schonegg, Edward

    1986-01-01

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which have undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed.

  15. Process for reducing beta activity in uranium

    DOEpatents

    Briggs, G.G.; Kato, T.R.; Schonegg, E.

    1985-04-11

    This invention is a method for lowering the beta radiation hazards associated with the casting of uranium. The method reduces the beta radiation emitted from the as-cast surfaces of uranium ingots. The method also reduces the amount of beta radiation emitters retained on the interiors of the crucibles that have been used to melt the uranium charges and which undergone cleaning in a remote handling facility. The lowering of the radioactivity is done by scavenging the beta emitters from the molten uranium with a molten mixture containing the fluorides of magnesium and calcium. The method provides a means of collection and disposal of the beta emitters in a manner that reduces radiation exposure to operating personnel in the work area where the ingots are cast and processed. 5 tabs.

  16. A spatial model of cellular molecular trafficking including active transport along microtubules.

    PubMed

    Cangiani, A; Natalini, R

    2010-12-21

    We consider models of Ran-driven nuclear transport of molecules such as proteins in living cells. The mathematical model presented is the first to take into account for the active transport of molecules along the cytoplasmic microtubules. All parameters entering the models are thoroughly discussed. The model is tested by numerical simulations based on discontinuous Galerkin finite element methods. The numerical experiments are compared to the behavior observed experimentally.

  17. Large Eddy Simulation of Transient Flow, Solidification, and Particle Transport Processes in Continuous-Casting Mold

    NASA Astrophysics Data System (ADS)

    Liu, Zhongqiu; Li, Linmin; Li, Baokuan; Jiang, Maofa

    2014-07-01

    The current study developed a coupled computational model to simulate the transient fluid flow, solidification, and particle transport processes in a slab continuous-casting mold. Transient flow of molten steel in the mold is calculated using the large eddy simulation. An enthalpy-porosity approach is used for the analysis of solidification processes. The transport of bubble and non-metallic inclusion inside the liquid pool is calculated using the Lagrangian approach based on the transient flow field. A criterion of particle entrapment in the solidified shell is developed using the user-defined functions of FLUENT software (ANSYS, Inc., Canonsburg, PA). The predicted results of this model are compared with the measurements of the ultrasonic testing of the rolled steel plates and the water model experiments. The transient asymmetrical flow pattern inside the liquid pool exhibits quite satisfactory agreement with the corresponding measurements. The predicted complex instantaneous velocity field is composed of various small recirculation zones and multiple vortices. The transport of particles inside the liquid pool and the entrapment of particles in the solidified shell are not symmetric. The Magnus force can reduce the entrapment ratio of particles in the solidified shell, especially for smaller particles, but the effect is not obvious. The Marangoni force can play an important role in controlling the motion of particles, which increases the entrapment ratio of particles in the solidified shell obviously.

  18. Coupled turbulent flow, heat, and solute transport in continuous casting processes

    NASA Astrophysics Data System (ADS)

    Aboutalebi, M. Reza; Hasan, M.; Guthrie, R. I. L.

    1995-08-01

    A fully coupled fluid flow, heat, and solute transport model was developed to analyze turbulent flow, solidification, and evolution of macrosegregation in a continuous billet caster. Transport equations of total mass, momentum, energy, and species for a binary iron-carbon alloy system were solved using a continuum model, wherein the equations are valid for the solid, liquid, and mushy zones in the casting. A modified version of the low-Reynolds number k-ɛ model was adopted to incorporate turbulence effects on transport processes in the system. A control-volume-based finite-difference procedure was employed to solve the conservation equations associated with appropriate boundary conditions. Because of high nonlinearity in the system of equations, a number of techniques were used to accelerate the convergence process. The effects of the parameters such as casting speed, steel grade, nozzle configuration on flow pattern, solidification profile, and carbon segregation were investigated. From the computed flow pattern, the trajectory of inclusion particles, as well as the density distribution of the particles, was calculated. Some of the computed results were compared with available experimental measurements, and reasonable agreements were obtained.

  19. Tau reduction prevents Aβ-induced axonal transport deficits by blocking activation of GSK3β

    PubMed Central

    Xu, Jordan C.; Fomenko, Vira; Miyamoto, Takashi; Suberbielle, Elsa; Knox, Joseph A.; Ho, Kaitlyn; Kim, Daniel H.; Yu, Gui-Qiu

    2015-01-01

    Axonal transport deficits in Alzheimer’s disease (AD) are attributed to amyloid β (Aβ) peptides and pathological forms of the microtubule-associated protein tau. Genetic ablation of tau prevents neuronal overexcitation and axonal transport deficits caused by recombinant Aβ oligomers. Relevance of these findings to naturally secreted Aβ and mechanisms underlying tau’s enabling effect are unknown. Here we demonstrate deficits in anterograde axonal transport of mitochondria in primary neurons from transgenic mice expressing familial AD-linked forms of human amyloid precursor protein. We show that these deficits depend on Aβ1–42 production and are prevented by tau reduction. The copathogenic effect of tau did not depend on its microtubule binding, interactions with Fyn, or potential role in neuronal development. Inhibition of neuronal activity, N-methyl-d-aspartate receptor function, or glycogen synthase kinase 3β (GSK3β) activity or expression also abolished Aβ-induced transport deficits. Tau ablation prevented Aβ-induced GSK3β activation. Thus, tau allows Aβ oligomers to inhibit axonal transport through activation of GSK3β, possibly by facilitating aberrant neuronal activity. PMID:25963821

  20. Investigation of the sediment transport processes using tracer stones in in alpine torrents

    NASA Astrophysics Data System (ADS)

    Spreitzer, Gabriel; Harb, Gabriele; Schneider, Josef

    2015-04-01

    Worldwide, every year numerous people die as a result of extreme weather conditions. Not only in less developed countries, also in Austria are we continuously facing the severe danger resulting from torrents. Therefore, risk prevention, risk analysis and forecast methods thus became more important. Geomorphological processes are often not easy to analyse. It is thus necessary to investigate the availability of sediments in the catchment area, the erosion processes of the sediment and the transport of the sediments along torrents. A domestic example concerning extreme events constitutes the Schöttlbach in the Upper Styrian town Oberwölz, which turned in the year 2011 into a dangerous torrent after heavy rainfall with up to 140 l/s in 2.5 hours and caused enormous damage, which runs into the millions. Due to this event the project ClimCatch has been started in 2012 in order to investigate the behavior of mountain creeks in the alpine catchment area considering the aspect of the advancing climate change. The main goal of the project is to analyse the geomorphic processes determining sediment transport in the river system and the measurement of bed load output. Several different methodologies are applied within the project to quantify river sediment dynamics. Discharge and sediment transport measurement equipment as well as hydrological stations are installed in the catchment area. For the observation and measurement of the sediment transport Large- and Small-Helley-Smith-Sampler and colour tracer stones are carried out. The measurements with the Small-Helley-Smith-Sampler determined a daily bed load of 1.5 t at the double mean discharge of about 900 l/s. The colour tracer stones, which are prepared as well characterized in the laboratory and exposed again in the river bed, gave information about the movement behaviour of these stones in case of flood events. Therefore, the position of the tracer stones were checked at regular intervals or after major rainfall in the

  1. Advances in Understanding Sorption and Transport Processes Affecting the Fate of Environmental Pollutants in the Subsurface

    NASA Astrophysics Data System (ADS)

    Karapanagioti, H. K.; Werner, D.; Werth, C.

    2012-04-01

    The results of a call for a special issue that is now in press by the Journal of Contaminant Hydrology will be presented. This special issue is edited by the authors and is entitled "Sorption and Transport Processes Affecting the Fate of Environmental Pollutants in the Subsurface". A short abstract of each paper will be presented along with the most interesting results. Nine papers were accepted. Pollutants studied include: biocolloids, metals (arsenic, chromium, nickel), organic compounds such as hydrocarbons, chlorinated hydrocarbons, micropollutants (PAHs, PCBs), pesticides (glyphosate, 2,4-D). Findings presented in the papers include a modified batch reactor system to study equilibrium-reactive transport problems of metals. Column studies along with theoretical approximations evaluate the combined effects of grain size and pore water velocity on the transport in water saturated porous media of three biocolloids. A polluted sediment remediation method is evaluated considering site-specific conditions through monitoring results and modelling. A field study points to glogging and also sorption as mechanisms affecting the effectiveness of sub-surface flow constructed wetlands. A new isotherm model combining modified traditionally used isotherms is proposed that can be used to simulate pH-dependent metal adsorption. Linear free energy relationships (LFERs) demonstrate ability to predict slight isotope shifts into the groundwater due to sorption. Possible modifications that improve the reliability of kinetic models and parameter values during the evaluation of experiments that assess the sorption of pesticides on soils are tested. Challenges in selecting groundwater pollutant fate and transport models that account for the effect of grain-scale sorption rate limitations are evaluated based on experimental results and are discussed based on the Damköhler number. Finally, a thorough review paper presents the impact of mineral micropores on the transport and fate of

  2. Understanding Microbial Reservoir Souring and Desouring Processes Using Reactive Transport Modeling

    NASA Astrophysics Data System (ADS)

    Cheng, Y.; Bouskill, N.; Hubbard, C. G.; Hubbard, S. S.; Ajo Franklin, J. B.; Li, L.; Engelbrektson, A. L.; Coates, J. D.; Surasani, V.

    2013-12-01

    Microbial sulfate reduction is the major metabolic process that leads to oil reservoir souring. Souring typically occurs when (sea)water is injected into the oil reservoir to maintain pressure and sweep remnant oil through the reservoir. Because biogenesis of hydrogen sulfide has detrimental impacts on oil production operations and can cause significant environmental and health problems, we strive to develop predictive understanding of reservoir souring and associated mitigation processes. Recent laboratory sediment column experiments have demonstrated the effectiveness of nitrate, chlorate and perchlorate treatments as souring control strategies. In this study, we describe the development of a reactive transport model that is based on the reaction mechanisms and kinetics revealed through the column experimental data. The model was used to simulate the temporal and spatial evolution of the primary chemical species (e.g. sulfate, sulfide, nitrate, chlorate and perchlorate) and the microbial dynamics involved in the souring and desouring processes. The growth and inhibition dynamics of the sulfate reducing bacterial population are explicitly simulated and constrained by energetics. Simulation of the laboratory experimental results show that the model captured the spatio-temporal trend of the chemical species and microbial guilds during both souring and desouring. Ongoing research is focusing on extending the reactive transport model to mechanistically understand, quantify, and predict souring and desouring processes within heterogeneous reservoirs as a step toward optimizing field scale souring control strategies.

  3. Decadal variation of the North Atlantic meridional heat transport and its relation to atmospheric processes

    NASA Astrophysics Data System (ADS)

    Martin, T.; Ruprecht, E.

    2007-02-01

    The effects of the meridional heat transport in the North Atlantic Ocean (HTR) on the north hemispheric climate are studied using the results of the coupled model ECHAM5/MPI-OM. Significant correlations exist between HTR and atmospheric processes over the Nordic Seas and the Eurasian continent only for low (periods longer than 40 years) and intermediate frequency variations (periods between 25 and 40 years). A positive HTR anomaly at 30°N is highly correlated with turbulent heat fluxes around 50°N. The transport through 70°N is directly related to the fluxes over the Nordic seas. From the correlation pattern with the atmospheric surface temperature and pressure one can conclude that the heat anomalies propagate along the cyclone tracks towards northeast over the Eurasian continent. The HRT anomalies are negatively correlated with the pressure over the Nordic seas and with the winter time anticyclone intensity over Siberia.

  4. A non-equilibrium thermodynamics model of multicomponent mass and heat transport in pervaporation processes

    NASA Astrophysics Data System (ADS)

    Villaluenga, Juan P. G.; Kjelstrup, Signe

    2012-12-01

    The framework of non-equilibrium thermodynamics (NET) is used to derive heat and mass transport equations for pervaporation of a binary mixture in a membrane. In this study, the assumption of equilibrium of the sorbed phase in the membrane and the adjacent phases at the feed and permeate sides of the membrane is abandoned, defining the interface properties using local equilibrium. The transport equations have been used to model the pervaporation of a water-ethanol mixture, which is typically encountered in the dehydration of organics. The water and ethanol activities and temperature profiles are calculated taking mass and heat coupling effects and surfaces into account. The NET approach is deemed good because the temperature results provided by the model are comparable to experimental results available for water-alcohol systems.

  5. Numerical simulation of fracture permeability evolution due to reactive transport and pressure solution processes