WorldWideScience

Sample records for lenticular tight gas

  1. Tight connection between fission gas discharge channels

    International Nuclear Information System (INIS)

    Jung, W.; Peehs, M.; Rau, P.; Krug, W.; Stechemesser, H.

    1978-01-01

    The invention is concerned with the tight connection between the fission gas discharge channel, leading away from the support plate of a gas-cooled reactor, and the top of the fuel element suspended from this support plate. The closure is designed to be gas-tight for the suspended as well as for the released fuel element. The tight connection has got an annular body resting on the core support plate in the mouth region of the fission gas discharge channel. This body is connected with the fission gas discharge channel in the fuel element top fitting via a gas-tight part and supported by a compression spring. Care is taken for sealing if the fuel element is removal. (RW) [de

  2. Gas tightness detecting method for overpack

    International Nuclear Information System (INIS)

    Harashima, Takeo; Hasegawa, Yasuyuki

    1999-01-01

    High level radioactive wastes and timing gas generation means for jetting out an inert gas after a predetermined period of time are contained together in a steel overpack. A steel lid is welded to the opening of the overpack so as to seal the high level radioactive wastes and the timing gas generation means. Then, the inert gas is jetted out from the timing gas generating device, and the gas tightness is detected by detecting the inert gas at the circumference of the overpack. Alternatively, a corrosion resistant coating layer having a gas generation means for jetting out an inert gas is coated at the circumference of a steel overpack containing high level radioactive wastes, and the overpack is sealed. The inert gas is generated from the gas generating means in the coating layer, and the inert gas at the periphery of the coating layer is detected to determine gas tightness. (N.H.)

  3. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1999-06-01

    Building upon the partitioning of the Greater Green River Basin (GGRB) that was conducted last quarter, the goal of the work this quarter has been to conclude evaluation of the Stratos well and the prototypical Green River Deep partition, and perform the fill resource evaluation of the Upper Cretaceous tight gas play, with the goal of defining target areas of enhanced natural fracturing. The work plan for the quarter of November 1-December 31, 1998 comprised four tasks: (1) Evaluation of the Green River Deep partition and the Stratos well and examination of potential opportunity for expanding the use of E and P technology to low permeability, naturally fractured gas reservoirs, (2) Gas field studies, and (3) Resource analysis of the balance of the partitions.

  4. Tight gas sand tax credit yields opportunities

    International Nuclear Information System (INIS)

    Lewis, F.W.; Osburn, A.S.

    1991-01-01

    The U.S. Internal Revenue Service on Apr. 1, 1991, released the inflation adjustments used in the calculations of Non-Conventional Fuel Tax Credits for 1990. The inflation adjustment, 1.6730, when applied to the base price of $3/bbl of oil equivalent, adjusts the tax credit to $5.019/bbl for oil and 86.53 cents/MMBTU for gas. The conversion factor for equivalent fuels is 5.8 MMBTU/bbl. Unfortunately, the tax credit for tight formation gas continues to be unadjusted for inflation and remains 52 cents/MMBTU. As many producers are aware, the Omnibus Budget Reconciliation Act of 1990 expanded the dates of eligibility and the usage for-Non-Conventional Fuel Tax Credits. Among other provisions, eligible wells may be placed in service until Jan. 1, 1992, and once in place may utilize the credit for production through Dec. 31, 2002. Both dates are 2 year extensions from previous regulations

  5. Naturally fractured tight gas reservoir detection optimization

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-11-30

    The work plan for October 1, 1997 to September 30, 1998 consisted of investigation of a number of topical areas. These topical areas were reported in four quarterly status reports, which were submitted to DOE earlier. These topical areas are reviewed in this volume. The topical areas covered during the year were: (1) Development of preliminary tests of a production method for determining areas of natural fracturing. Advanced Resources has demonstrated that such a relationship exists in the southern Piceance basin tight gas play. Natural fracture clusters are genetically related to stress concentrations (also called stress perturbations) associated with local deformation such a faulting. The mechanical explanation of this phenomenon is that deformation generally initiates at regions where the local stress field is elevated beyond the regional. (2) Regional structural and geologic analysis of the Greater Green River Basin (GGRB). Application of techniques developed and demonstrated during earlier phases of the project for sweet-spot delineation were demonstrated in a relatively new and underexplored play: tight gas from continuous-typeUpper Cretaceous reservoirs of the Greater Green River Basin (GGRB). The effort included data acquisition/processing, base map generation, geophysical and remote sensing analysis and the integration of these data and analyses. (3) Examination of the Table Rock field area in the northern Washakie Basin of the Greater Green River Basin. This effort was performed in support of Union Pacific Resources- and DOE-planned horizontal drilling efforts. The effort comprised acquisition of necessary seismic data and depth-conversion, mapping of major fault geometry, and analysis of displacement vectors, and the development of the natural fracture prediction. (4) Greater Green River Basin Partitioning. Building on fundamental fracture characterization work and prior work performed under this contract, namely structural analysis using satellite and

  6. US production of natural gas from tight reservoirs

    International Nuclear Information System (INIS)

    1993-01-01

    For the purposes of this report, tight gas reservoirs are defined as those that meet the Federal Energy Regulatory Commission's (FERC) definition of tight. They are generally characterized by an average reservoir rock permeability to gas of 0.1 millidarcy or less and, absent artificial stimulation of production, by production rates that do not exceed 5 barrels of oil per day and certain specified daily volumes of gas which increase with the depth of the reservoir. All of the statistics presented in this report pertain to wells that have been classified, from 1978 through 1991, as tight according to the FERC; i.e., they are ''legally tight'' reservoirs. Additional production from ''geologically tight'' reservoirs that have not been classified tight according to the FERC rules has been excluded. This category includes all producing wells drilled into legally designated tight gas reservoirs prior to 1978 and all producing wells drilled into physically tight gas reservoirs that have not been designated legally tight. Therefore, all gas production referenced herein is eligible for the Section 29 tax credit. Although the qualification period for the credit expired at the end of 1992, wells that were spudded (began to be drilled) between 1978 and May 1988, and from November 5, 1990, through year end 1992, are eligible for the tax credit for a subsequent period of 10 years. This report updates the EIA's tight gas production information through 1991 and considers further the history and effect on tight gas production of the Federal Government's regulatory and tax policy actions. It also provides some high points of the geologic background needed to understand the nature and location of low-permeability reservoirs

  7. Elliptical and lenticular galaxies evolution

    International Nuclear Information System (INIS)

    Vigroux, L.

    1981-01-01

    Different evolutionnary models for elliptical and lenticular galaxies are discussed. In the first part, we show that, at least some peculiar early types galaxies exhibit some activity. Then we describe the observationnal constraints: the color-magnitude diagram, the color gradient and the high metallicity of intraclusters gas. Among the different models, only the dissipation collapse followed by a hot wind driven by supernovae explosion explain in a natural way these constraints. Finally, the origin of SO is briefly discussed [fr

  8. Western tight gas sands advanced logging workshop proceedings

    Energy Technology Data Exchange (ETDEWEB)

    Jennings, J B; Carroll, Jr, H B [eds.

    1982-04-01

    An advanced logging research program is one major aspect of the Western Tight Sands Program. Purpose of this workshop is to help BETC define critical logging needs for tight gas sands and to allow free interchange of ideas on all aspects of the current logging research program. Sixteen papers and abstracts are included together with discussions. Separate abstracts have been prepared for the 12 papers. (DLC)

  9. Prediction of Gas Leak Tightness of Superplastically Formed Products

    NARCIS (Netherlands)

    Snippe, Q.H.C.; Meinders, Vincent T.; Barlat, F; Moon, Y.H.; Lee, M.G.

    2010-01-01

    In some applications, in this case an aluminium box in a subatomic particle detector containing highly sensitive detecting devices, it is important that a formed sheet should show no gas leak from one side to the other. In order to prevent a trial-and-error procedure to make this leak tight box, a

  10. 18 CFR 270.304 - Tight formation gas.

    Science.gov (United States)

    2010-04-01

    ... 18 Conservation of Power and Water Resources 1 2010-04-01 2010-04-01 false Tight formation gas. 270.304 Section 270.304 Conservation of Power and Water Resources FEDERAL ENERGY REGULATORY COMMISSION... before January 1, 1980; and (2) The applicant has no knowledge of any information not described in the...

  11. Advanced Hydraulic Fracturing Technology for Unconventional Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Stephen Holditch; A. Daniel Hill; D. Zhu

    2007-06-19

    The objectives of this project are to develop and test new techniques for creating extensive, conductive hydraulic fractures in unconventional tight gas reservoirs by statistically assessing the productivity achieved in hundreds of field treatments with a variety of current fracturing practices ranging from 'water fracs' to conventional gel fracture treatments; by laboratory measurements of the conductivity created with high rate proppant fracturing using an entirely new conductivity test - the 'dynamic fracture conductivity test'; and by developing design models to implement the optimal fracture treatments determined from the field assessment and the laboratory measurements. One of the tasks of this project is to create an 'advisor' or expert system for completion, production and stimulation of tight gas reservoirs. A central part of this study is an extensive survey of the productivity of hundreds of tight gas wells that have been hydraulically fractured. We have been doing an extensive literature search of the SPE eLibrary, DOE, Gas Technology Institute (GTI), Bureau of Economic Geology and IHS Energy, for publicly available technical reports about procedures of drilling, completion and production of the tight gas wells. We have downloaded numerous papers and read and summarized the information to build a database that will contain field treatment data, organized by geographic location, and hydraulic fracture treatment design data, organized by the treatment type. We have conducted experimental study on 'dynamic fracture conductivity' created when proppant slurries are pumped into hydraulic fractures in tight gas sands. Unlike conventional fracture conductivity tests in which proppant is loaded into the fracture artificially; we pump proppant/frac fluid slurries into a fracture cell, dynamically placing the proppant just as it occurs in the field. From such tests, we expect to gain new insights into some of the critical

  12. Coalbed methane and tight gas no longer unconventional resources

    International Nuclear Information System (INIS)

    Gatens, M.

    2006-01-01

    Unconventional gas refers to natural gas contained in difficult-to-produce formations that require special drilling and completion techniques to achieve commercial production. It includes tight gas, coal seams, organic shales, and gas hydrates. Canada's vast unconventional gas resource is becoming an increasingly important part of the country's gas supply. The emergence of unconventional gas production in Canada over the past several years has made the unconventional increasingly conventional in terms of industry activity. It was suggested that in order to realize the potential for unconventional gas in Canada, all stakeholders should engage to ensure the development is environmentally responsible. Unconventional gas accounts for nearly one third of U.S. gas production. It also accounts for nearly 5 Bcf per day and growing. The impetus to this sudden growth has been the gradual and increasing contribution of tight sands and limes to Canadian production, which accounts for more than 4 Bcf per day. Coalbed methane (CBM) is at 0.5 Bcf per day and growing. In response to expectations that CBM will reach 2 to 3 Bcf per day over the next 2 decades, Canadian producers are placing more emphasis on unconventional resource plays, including organic shales and gas hydrates. As such, significant growth of unconventional gas is anticipated. This growth will be facilitated by the adoption of U.S..-developed technologies and new Canadian technologies. It was suggested that research and development will be key to unlocking the unconventional gas potential. It was also suggested that the already existing, strong regulatory structure should continue in order to accommodate this growth in a sustainable manner. figs

  13. Gas-Water Flow Behavior in Water-Bearing Tight Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Renyi Cao

    2017-01-01

    Full Text Available Some tight sandstone gas reservoirs contain mobile water, and the mobile water generally has a significant impact on the gas flowing in tight pores. The flow behavior of gas and water in tight pores is different than in conventional formations, yet there is a lack of adequate models to predict the gas production and describe the gas-water flow behaviors in water-bearing tight gas reservoirs. Based on the experimental results, this paper presents mathematical models to describe flow behaviors of gas and water in tight gas formations; the threshold pressure gradient, stress sensitivity, and relative permeability are all considered in our models. A numerical simulator using these models has been developed to improve the flow simulation accuracy for water-bearing tight gas reservoirs. The results show that the effect of stress sensitivity becomes larger as water saturation increases, leading to a fast decline of gas production; in addition, the nonlinear flow of gas phase is aggravated with the increase of water saturation and the decrease of permeability. The gas recovery decreases when the threshold pressure gradient (TPG and stress sensitivity are taken into account. Therefore, a reasonable drawdown pressure should be set to minimize the damage of nonlinear factors to gas recovery.

  14. Gas transport in tight porous media Gas kinetic approach

    DEFF Research Database (Denmark)

    Shapiro, Alexander; Wesselingh, Johannes

    2008-01-01

    We describe the flow of gas in a porous medium in the kinetic regime, where the viscous flow structure is not formed in separate pores. Special attention is paid to the dense kinetic regime, where the interactions within the gas are as important as the interaction with the porous medium....... The transport law for this regime is derived by means of the gas kinetic theory, in the framework of the model of "heavy gas in light one". The computations of the gas kinetic theory are confirmed by the dimension analysis and a simplified derivation revealing the considerations behind the kinetic derivation...

  15. Gas transport in tight porous media Gas kinetic approach

    NARCIS (Netherlands)

    Shapiro, A. A.; Wesselingh, Johannes

    2008-01-01

    We describe the flow of gas in a porous medium in the kinetic regime, where the viscous flow structure is not formed in separate pores. Special attention is paid to the dense kinetic regime, where the interactions within the gas are as important as the interaction with the porous medium. The

  16. Accumulation mechanism of tight sandstone gas in low gas generation intensity area

    Directory of Open Access Journals (Sweden)

    Fudong Zhang

    2017-04-01

    Full Text Available Before 11th five-year plan, geologists proposed the viewpoint that the gas generation intensity that's more than 20 × 108 m3/km2 was an important condition for forming conventional large gas fields. However, recent exploration findings indicate that large-area tight sandstone gas that has a gas generation intensity of less than 20 × 108 m3/km2 can still form reserves. This is an area worth exploring. Through innovative accumulation simulation, microscopic pore throat analysis of reservoirs, and dissection of typical gas reservoirs, several factors have been established, including the comprehensive evaluation models involving gas charging pressure, reservoir physical properties, and lower gas generation limit. In addition, the paper has made it certain that the tight sandstone gas in a low gas generation intensity area has accumulation characteristics such as “partial water displacing, long-term gas supply, gas control by tight reservoirs of scale, gas abundance control by physical properties, combined control and enrichment of dominant resources, etc.”, and has proposed the viewpoint that this area has the accumulation mechanism that of a “non-dominant transportation, long-term continuous charging, reservoir controlling by physical property difference, and enrichment in partial sweet spots” and shows discontinuous “patchy distribution” on the plane. This is of much significance to fine exploration and development of the trillion cubic meter resources of the low gas generation intensity areas in the west of Sulige gas field.

  17. Naturally fractured tight gas reservoir detection optimization. Final report

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-11-19

    This DOE-funded research into seismic detection of natural fractures is one of six projects within the DOE`s Detection and Analysis of Naturally Fractured Gas Reservoirs Program, a multidisciplinary research initiative to develop technology for prediction, detection, and mapping of naturally fractured gas reservoirs. The demonstration of successful seismic techniques to locate subsurface zones of high fracture density and to guide drilling orientation for enhanced fracture permeability will enable better returns on investments in the development of the vast gas reserves held in tight formations beneath the Rocky Mountains. The seismic techniques used in this project were designed to capture the azimuthal anisotropy within the seismic response. This seismic anisotropy is the result of the symmetry in the rock fabric created by aligned fractures and/or unequal horizontal stresses. These results may be compared and related to other lines of evidence to provide cross-validation. The authors undertook investigations along the following lines: Characterization of the seismic anisotropy in three-dimensional, P-wave seismic data; Characterization of the seismic anisotropy in a nine-component (P- and S-sources, three-component receivers) vertical seismic profile; Characterization of the seismic anisotropy in three-dimensional, P-to-S converted wave seismic data (P-wave source, three-component receivers); and Description of geological and reservoir-engineering data that corroborate the anisotropy: natural fractures observed at the target level and at the surface, estimation of the maximum horizontal stress in situ, and examination of the flow characteristics of the reservoir.

  18. Creating lenticular galaxies with mergers

    Science.gov (United States)

    Querejeta, Miguel; Eliche-Moral, M. Carmen; Tapia, Trinidad; Borlaff, Alejandro; van de Ven, Glenn; Lyubenova, Mariya; Martig, Marie; Falcón-Barroso, Jesús; Méndez-Abreu, Jairo; Zamorano, Jaime; Gallego, Jesús

    2017-03-01

    Lenticular galaxies (S0s) represent the majority of early-type galaxies in the local Universe, but their formation channels are still poorly understood. While galaxy mergers are obvious pathways to suppress star formation and increase bulge sizes, the marked parallelism between spiral and lenticular galaxies (e.g. photometric bulge-disc coupling) seemed to rule out a potential merger origin. Here, we summarise our recent work in which we have shown, through N-body numerical simulations, that disc-dominated lenticulars can emerge from major mergers of spiral galaxies, in good agreement with observational photometric scaling relations. Moreover, we show that mergers simultaneously increase the light concentration and reduce the angular momentum relative to their spiral progenitors. This explains the mismatch in angular momentum and concentration between spirals and lenticulars recently revealed by CALIFA observations, which is hard to reconcile with simple fading mechanisms (e.g. ram-pressure stripping).

  19. RELIABILITY OF LENTICULAR EXPANSION COMPENSATORS

    Directory of Open Access Journals (Sweden)

    Gabriel BURLACU,

    2011-11-01

    Full Text Available Axial lenticular compensators are made to take over the longitudinal heat expansion, shock , vibration and noise, made elastic connections for piping systems. In order to have a long life for installations it is necessary that all elements, including lenticular compensators, have a good reliability. This desire can be did by technology of manufactoring and assembly of compensators, the material for lenses and by maintenance.of compensator

  20. Feasibility study on application of volume acid fracturing technology to tight gas carbonate reservoir development

    Directory of Open Access Journals (Sweden)

    Nianyin Li

    2015-09-01

    Full Text Available How to effectively develop tight-gas carbonate reservoir and achieve high recovery is always a problem for the oil and gas industry. To solve this problem, domestic petroleum engineers use the combination of the successful experiences of North American shale gas pools development by stimulated reservoir volume (SRV fracturing with the research achievements of Chinese tight gas development by acid fracturing to propose volume acid fracturing technology for fractured tight-gas carbonate reservoir, which has achieved a good stimulation effect in the pilot tests. To determine what reservoir conditions are suitable to carry out volume acid fracturing, this paper firstly introduces volume acid fracturing technology by giving the stimulation mechanism and technical ideas, and initially analyzes the feasibility by the comparison of reservoir characteristics of shale gas with tight-gas carbonate. Then, this paper analyzes the validity and limitation of the volume acid fracturing technology via the analyses of control conditions for volume acid fracturing in reservoir fracturing performance, natural fracture, horizontal principal stress difference, orientation of in-situ stress and natural fracture, and gives the solution for the limitation. The study results show that the volume acid fracturing process can be used to greatly improve the flow environment of tight-gas carbonate reservoir and increase production; the incremental or stimulation response is closely related with reservoir fracturing performance, the degree of development of natural fracture, the small intersection angle between hydraulic fracture and natural fracture, the large horizontal principal stress difference is easy to form a narrow fracture zone, and it is disadvantageous to create fracture network, but the degradable fiber diversion technology may largely weaken the disadvantage. The practices indicate that the application of volume acid fracturing process to the tight-gas carbonate

  1. Characterization of Tight Gas Reservoir Pore Structure Using USANS/SANS and Gas Adsorption Analysis

    Energy Technology Data Exchange (ETDEWEB)

    Clarkson, Christopher R [ORNL; He, Lilin [ORNL; Agamalian, Michael [ORNL; Melnichenko, Yuri B [ORNL; Mastalerz, Maria [Indiana Geological Survey; Bustin, Mark [University of British Columbia, Vancouver; Radlinski, Andrzej Pawell [ORNL; Blach, Tomasz P [ORNL

    2012-01-01

    Small-angle and ultra-small-angle neutron scattering (SANS and USANS) measurements were performed on samples from the Triassic Montney tight gas reservoir in Western Canada in order to determine the applicability of these techniques for characterizing the full pore size spectrum and to gain insight into the nature of the pore structure and its control on permeability. The subject tight gas reservoir consists of a finely laminated siltstone sequence; extensive cementation and moderate clay content are the primary causes of low permeability. SANS/USANS experiments run at ambient pressure and temperature conditions on lithologically-diverse sub-samples of three core plugs demonstrated that a broad pore size distribution could be interpreted from the data. Two interpretation methods were used to evaluate total porosity, pore size distribution and surface area and the results were compared to independent estimates derived from helium porosimetry (connected porosity) and low-pressure N{sub 2} and CO{sub 2} adsorption (accessible surface area and pore size distribution). The pore structure of the three samples as interpreted from SANS/USANS is fairly uniform, with small differences in the small-pore range (< 2000 {angstrom}), possibly related to differences in degree of cementation, and mineralogy, in particular clay content. Total porosity interpreted from USANS/SANS is similar to (but systematically higher than) helium porosities measured on the whole core plug. Both methods were used to estimate the percentage of open porosity expressed here as a ratio of connected porosity, as established from helium adsorption, to the total porosity, as estimated from SANS/USANS techniques. Open porosity appears to control permeability (determined using pressure and pulse-decay techniques), with the highest permeability sample also having the highest percentage of open porosity. Surface area, as calculated from low-pressure N{sub 2} and CO{sub 2} adsorption, is significantly less

  2. Leak testing of bubble-tight dampers using tracer gas techniques

    Energy Technology Data Exchange (ETDEWEB)

    Lagus, P.L. [Lagus Applied Technology, Inc., San Diego, CA (United States); DuBois, L.J. [Commonwealth Edison, Zion, IL (United States); Fleming, K.M. [NCS Corporation, Columbus, OH (United States)] [and others

    1995-02-01

    Recently tracer gas techniques have been applied to the problem of measuring the leakage across an installed bubble-tight damper. A significant advantage of using a tracer gas technique is that quantitative leakage data are obtained under actual operating differential pressure conditions. Another advantage is that leakage data can be obtained using relatively simple test setups that utilize inexpensive materials without the need to tear ducts apart, fabricate expensive blank-off plates, and install test connections. Also, a tracer gas technique can be used to provide an accurate field evaluation of the performance of installed bubble-tight dampers on a periodic basis. Actual leakage flowrates were obtained at Zion Generating Station on four installed bubble-tight dampers using a tracer gas technique. Measured leakage rates ranged from 0.01 CFM to 21 CFM. After adjustment and subsequent retesting, the 21 CFM damper leakage was reduced to a leakage of 3.8 CFM. In light of the current regulatory climate and the interest in Control Room Habitability issues, imprecise estimates of critical air boundary leakage rates--such as through bubble-tight dampers--are not acceptable. These imprecise estimates can skew radioactive dose assessments as well as chemical contaminant exposure calculations. Using a tracer gas technique, the actual leakage rate can be determined. This knowledge eliminates a significant source of uncertainty in both radioactive dose and/or chemical exposure assessments.

  3. Potential restrictions for CO2 sequestration sites due to shale and tight gas production.

    Science.gov (United States)

    Elliot, T R; Celia, M A

    2012-04-03

    Carbon capture and geological sequestration is the only available technology that both allows continued use of fossil fuels in the power sector and reduces significantly the associated CO(2) emissions. Geological sequestration requires a deep permeable geological formation into which captured CO(2)can be injected, and an overlying impermeable formation, called a caprock, that keeps the buoyant CO(2) within the injection formation. Shale formations typically have very low permeability and are considered to be good caprock formations. Production of natural gas from shale and other tight formations involves fracturing the shale with the explicit objective to greatly increase the permeability of the shale. As such, shale gas production is in direct conflict with the use of shale formations as a caprock barrier to CO(2) migration. We have examined the locations in the United States where deep saline aquifers, suitable for CO(2) sequestration, exist, as well as the locations of gas production from shale and other tight formations. While estimated sequestration capacity for CO(2) sequestration in deep saline aquifers is large, up to 80% of that capacity has areal overlap with potential shale-gas production regions and, therefore, could be adversely affected by shale and tight gas production. Analysis of stationary sources of CO(2) shows a similar effect: about two-thirds of the total emissions from these sources are located within 20 miles of a deep saline aquifer, but shale and tight gas production could affect up to 85% of these sources. These analyses indicate that colocation of deep saline aquifers with shale and tight gas production could significantly affect the sequestration capacity for CCS operations. This suggests that a more comprehensive management strategy for subsurface resource utilization should be developed.

  4. Production of Natural Gas and Fluid Flow in Tight Sand Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Maria Cecilia Bravo

    2006-06-30

    This document reports progress of this research effort in identifying relationships and defining dependencies between macroscopic reservoir parameters strongly affected by microscopic flow dynamics and production well performance in tight gas sand reservoirs. These dependencies are investigated by identifying the main transport mechanisms at the pore scale that should affect fluids flow at the reservoir scale. A critical review of commercial reservoir simulators, used to predict tight sand gas reservoir, revealed that many are poor when used to model fluid flow through tight reservoirs. Conventional simulators ignore altogether or model incorrectly certain phenomena such as, Knudsen diffusion, electro-kinetic effects, ordinary diffusion mechanisms and water vaporization. We studied the effect of Knudsen's number in Klinkenberg's equation and evaluated the effect of different flow regimes on Klinkenberg's parameter b. We developed a model capable of explaining the pressure dependence of this parameter that has been experimentally observed, but not explained in the conventional formalisms. We demonstrated the relevance of this, so far ignored effect, in tight sands reservoir modeling. A 2-D numerical simulator based on equations that capture the above mentioned phenomena was developed. Dynamic implications of new equations are comprehensively discussed in our work and their relative contribution to the flow rate is evaluated. We performed several simulation sensitivity studies that evidenced that, in general terms, our formalism should be implemented in order to get more reliable tight sands gas reservoirs' predictions.

  5. Naturally fractured tight gas: Gas reservoir detection optimization. Quarterly report, January 1--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1997-12-31

    Economically viable natural gas production from the low permeability Mesaverde Formation in the Piceance Basin, Colorado requires the presence of an intense set of open natural fractures. Establishing the regional presence and specific location of such natural fractures is the highest priority exploration goal in the Piceance and other western US tight, gas-centered basins. Recently, Advanced Resources International, Inc. (ARI) completed a field program at Rulison Field, Piceance Basin, to test and demonstrate the use of advanced seismic methods to locate and characterize natural fractures. This project began with a comprehensive review of the tectonic history, state of stress and fracture genesis of the basin. A high resolution aeromagnetic survey, interpreted satellite and SLAR imagery, and 400 line miles of 2-D seismic provided the foundation for the structural interpretation. The central feature of the program was the 4.5 square mile multi-azimuth 3-D seismic P-wave survey to locate natural fracture anomalies. The interpreted seismic attributes are being tested against a control data set of 27 wells. Additional wells are currently being drilled at Rulison, on close 40 acre spacings, to establish the productivity from the seismically observed fracture anomalies. A similar regional prospecting and seismic program is being considered for another part of the basin. The preliminary results indicate that detailed mapping of fault geometries and use of azimuthally defined seismic attributes exhibit close correlation with high productivity gas wells. The performance of the ten new wells, being drilled in the seismic grid in late 1996 and early 1997, will help demonstrate the reliability of this natural fracture detection and mapping technology.

  6. Simulation of Gas Transport in Tight/Shale Gas Reservoirs by a Multicomponent Model Based on PEBI Grid

    OpenAIRE

    Zhang, Longjun; Li, Daolun; Wang, Lei; Lu, Detang

    2015-01-01

    The ultra-low permeability and nanosize pores of tight/shale gas reservoir would lead to non-Darcy flow including slip flow, transition flow, and free molecular flow, which cannot be described by traditional Darcy’s law. The organic content often adsorbs some gas content, while the adsorbed amount for different gas species is different. Based on these facts, we develop a new compositional model based on unstructured PEBI (perpendicular bisection) grid, which is able to characterize non-Darcy ...

  7. Assessment of Permian tight oil and gas resources in the Junggar basin of China, 2016

    Science.gov (United States)

    Potter, Christopher J.; Schenk, Christopher J.; Tennyson, Marilyn E.; Klett, Timothy R.; Gaswirth, Stephanie B.; Leathers-Miller, Heidi M.; Finn, Thomas M.; Brownfield, Michael E.; Pitman, Janet K.; Mercier, Tracey J.; Le, Phuong A.; Drake, Ronald M.

    2017-04-05

    Using a geology-based assessment methodology, the U.S. Geological Survey estimated undiscovered, technically recoverable mean resources of 764 million barrels of oil and 3.5 trillion cubic feet of gas in tight reservoirs in the Permian Lucaogou Formation in the Junggar basin of northwestern China.

  8. Naturally fractured tight gas reservoir detection optimization. Quarterly report, January 1, 1997--March 31, 1997

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-04-01

    This document contains the quarterly report dated January 1-March 31, 1997 for the Naturally Fractured Tight Gas Reservoir Detection Optimization project. Topics covered in this report include AVOA modeling using paraxial ray tracing, AVOA modeling for gas- and water-filled fractures, 3-D and 3-C processing, and technology transfer material. Several presentations from a Geophysical Applications Workshop workbook, workshop schedule, and list of workshop attendees are also included.

  9. Simulation of Gas Transport in Tight/Shale Gas Reservoirs by a Multicomponent Model Based on PEBI Grid

    Directory of Open Access Journals (Sweden)

    Longjun Zhang

    2015-01-01

    Full Text Available The ultra-low permeability and nanosize pores of tight/shale gas reservoir would lead to non-Darcy flow including slip flow, transition flow, and free molecular flow, which cannot be described by traditional Darcy’s law. The organic content often adsorbs some gas content, while the adsorbed amount for different gas species is different. Based on these facts, we develop a new compositional model based on unstructured PEBI (perpendicular bisection grid, which is able to characterize non-Darcy flow including slip flow, transition flow, and free molecular flow and the multicomponent adsorption in tight/shale gas reservoirs. With the proposed model, we study the effect of non-Darcy flow, length of the hydraulic fracture, and initial gas composition on gas production. The results show both non-Darcy flow and fracture length have significant influence on gas production. Ignoring non-Darcy flow would underestimate 67% cumulative gas production in lower permeable gas reservoirs. Gas production increases with fracture length. In lower permeable reservoirs, gas production increases almost linearly with the hydraulic fracture length. However, in higher permeable reservoirs, the increment of the former gradually decreases with the increase in the latter. The results also show that the presence of CO2 in the formation would lower down gas production.

  10. Imaging pore space in tight gas sandstone reservoir: insights from broad ion beam cross-sectioning

    Directory of Open Access Journals (Sweden)

    Konstanty J.

    2010-06-01

    Full Text Available Monetization of tight gas reservoirs, which contain significant gas reserves world-wide, represents a challenge for the entire oil and gas industry. The development of new technologies to enhance tight gas reservoir productivity is strongly dependent on an improved understanding of the rock properties and especially the pore framework. Numerous methods are now available to characterize sandstone cores. However, the pore space characterization at pore scale remains difficult due to the fine pore size and delicate sample preparation, and has thus been mostly indirectly inferred until now. Here we propose a new method of ultra high-resolution petrography combining high resolution SEM and argon ion beam cross sectioning (BIB, Broad Ion Beam which prepares smooth and damage free surfaces. We demonstrate this method using the example of Permian (Rotliegend age tight gas sandstone core samples. The combination of Ar-beam cross-sectioning facility and high-resolution SEM imaging has the potential to result in a step change in the understanding of pore geometries, in terms of its morphology, spatial distribution and evolution based on the generation of unprecedented image quality and resolution enhancing the predictive reliability of image analysis.

  11. Pore Structure and Limit Pressure of Gas Slippage Effect in Tight Sandstone

    Directory of Open Access Journals (Sweden)

    Lijun You

    2013-01-01

    Full Text Available Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit pressure increases with the decreasing in permeability and has close relation with pore structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment.

  12. Pore structure and limit pressure of gas slippage effect in tight sandstone.

    Science.gov (United States)

    You, Lijun; Xue, Kunlin; Kang, Yili; Liao, Yi; Kong, Lie

    2013-01-01

    Gas slip effect is an important mechanism that the gas flow is different from liquid flow in porous media. It is generally considered that the lower the permeability in porous media is, the more severe slip effect of gas flow will be. We design and then carry out experiments with the increase of backpressure at the outlet of the core samples based on the definition of gas slip effect and in view of different levels of permeability of tight sandstone reservoir. This study inspects a limit pressure of the gas slip effect in tight sandstones and analyzes the characteristic parameter of capillary pressure curves. The experimental results indicate that gas slip effect can be eliminated when the backpressure reaches a limit pressure. When the backpressure exceeds the limit pressure, the measured gas permeability is a relatively stable value whose range is less than 3% for a given core sample. It is also found that the limit pressure increases with the decreasing in permeability and has close relation with pore structure of the core samples. The results have an important influence on correlation study on gas flow in porous medium, and are beneficial to reduce the workload of laboratory experiment.

  13. Economic evaluation on tight sandstone gas development projects in China and recommendation on fiscal and taxation support policies

    Directory of Open Access Journals (Sweden)

    Zhen Yang

    2016-11-01

    Full Text Available China is rich in tight sandstone gas resources (“tight gas” for short. For example, the Sulige Gasfield in the Ordos Basin and the Upper Triassic Xujiahe Fm gas reservoir in the Sichuan Basin are typical tight gas reservoirs. In the past decade, tight gas reserve and production both have increased rapidly in China, but tight gas reservoirs are always managed as conventional gas reservoirs without effective fiscal, taxation and policy supports. The potential of sustainable tight gas production increase is obviously restricted. The tight gas development projects represented by the Sulige Gasfield have failed to make profit for a long period, and especially tight gas production has presented a slight decline since 2015. In this paper, a new economic evaluation method was proposed for tight gas development projects. The new method was designed to verify the key parameters (e.g. production decline rate and single-well economic service life depending on tight gas development and production characteristics, and perform the depreciation by using the production method. Furthermore, the possibility that the operation cost may rise due to pressure-boosting production and intermittent opening of gas wells is considered. The method was used for the tight gas development project of Sulige Gasfield, showing that its profit level is much lower than the enterprise's cost level of capital. In order to support a sustainable development of tight gas industry in China, it is recommended that relevant authorities issue value-added tax (VAT refund policy as soon as possible. It is necessary to restore the non-resident gas gate price of the provinces where tight gas is produced to the fair and reasonable level in addition to the fiscal subsidy of CNY0.24/m3, or offer the fiscal subsidy of CNY0.32/m3 directly based on the on-going gate price. With these support policies, tax income is expected to rise directly, fiscal expenditure will not increase, and gas

  14. Shale Gas and Tight Oil: A Panacea for the Energy Woes of America?

    Science.gov (United States)

    Hughes, J. D.

    2012-12-01

    Shale gas has been heralded as a "game changer" in the struggle to meet America's demand for energy. The "Pickens Plan" of Texas oil and gas pioneer T.Boone Pickens suggests that gas can replace coal for much of U.S. electricity generation, and oil for, at least, truck transportation1. Industry lobby groups such as ANGA declare "that the dream of clean, abundant, home grown energy is now reality"2. In Canada, politicians in British Columbia are racing to export the virtual bounty of shale gas via LNG to Asia (despite the fact that Canadian gas production is down 16 percent from its 2001 peak). And the EIA has forecast that the U.S. will become a net exporter of gas by 20213. Similarly, recent reports from Citigroup and Harvard suggest that an oil glut is on the horizon thanks in part to the application of fracking technology to formerly inaccessible low permeability tight oil plays. The fundamentals of well costs and declines belie this optimism. Shale gas is expensive gas. In the early days it was declared that "continuous plays" like shale gas were "manufacturing operations", and that geology didn't matter. One could drill a well anywhere, it was suggested, and expect consistent production. Unfortunately, Mother Nature always has the last word, and inevitably the vast expanses of purported potential shale gas resources contracted to "core" areas, where geological conditions were optimal. The cost to produce shale gas ranges from 4.00 per thousand cubic feet (mcf) to 10.00, depending on the play. Natural gas production is a story about declines which now amount to 32% per year in the U.S. So 22 billion cubic feet per day of production now has to be replaced each year to keep overall production flat. At current prices of 2.50/mcf, industry is short about 50 billion per year in cash flow to make this happen4. As a result I expect falling production and rising prices in the near to medium term. Similarly, tight oil plays in North Dakota and Texas have been heralded

  15. Analytical modeling of coupled flow and geomechanics for vertical fractured well in tight gas reservoirs

    Directory of Open Access Journals (Sweden)

    Wang Ruifei

    2017-12-01

    Full Text Available The mathematical model of coupled flow and geomechanics for a vertical fractured well in tight gas reservoirs was established. The analytical modeling of unidirectional flow and radial flow was achieved by Laplace transforms and integral transforms. The results show that uncoupled flow would lead to an overestimate in performance of a vertical fractured well, especially in the later stage. The production rate decreases with elastic modulus because porosity and permeability decrease accordingly. Drawdown pressure should be optimized to lower the impact of coupled flow and geomechanics as a result of permeability decreasing. Production rate increases with fracture half-length significantly in the initial stage and becomes stable gradually. This study could provide a theoretical basis for effective development of tight gas reservoirs.

  16. Analytical modeling of coupled flow and geomechanics for vertical fractured well in tight gas reservoirs

    Science.gov (United States)

    Wang, Ruifei; Gao, Xuhua; Song, Hongqing; Shang, Xinchun

    2017-12-01

    The mathematical model of coupled flow and geomechanics for a vertical fractured well in tight gas reservoirs was established. The analytical modeling of unidirectional flow and radial flow was achieved by Laplace transforms and integral transforms. The results show that uncoupled flow would lead to an overestimate in performance of a vertical fractured well, especially in the later stage. The production rate decreases with elastic modulus because porosity and permeability decrease accordingly. Drawdown pressure should be optimized to lower the impact of coupled flow and geomechanics as a result of permeability decreasing. Production rate increases with fracture half-length significantly in the initial stage and becomes stable gradually. This study could provide a theoretical basis for effective development of tight gas reservoirs.

  17. Why are brittleness and fracability not equivalent in designing hydraulic fracturing in tight shale gas reservoirs

    Directory of Open Access Journals (Sweden)

    Mao Bai

    2016-03-01

    With the objective review and sensible definition of brittleness used in the present petro-physical field to identify the desirable fracturing intervals, the paper presents the ambiguities of using the brittleness to define the formation fracability and points out that the formation brittleness can be unrelated to the formation fracability. As an alternative approach, the paper provides an effective method to define the most fracable formation intervals in designing the hydraulic fracturing in tight shale gas formations.

  18. Enhanced recovery of unconventional gas. Volume II. The program. [Tight gas basins; Devonian shale; coal seams; geopressured aquifers

    Energy Technology Data Exchange (ETDEWEB)

    Kuuskraa, V.A.; Brashear, J.P.; Doscher, T.M.; Elkins, L.E.

    1978-10-01

    This study was conducted to assist public decision-makers in selecting among many choices to obtain new gas supplies by addressing 2 questions: 1) how severe is the need for additional future supplies of natural gas, and what is the economic potential of providing part of future supply through enhanced recovery from unconventional natural gas resources. The study also serves to assist the DOE in designing a cost-effective R and D program to stimulate industry to recover this unconventional gas and to produce it sooner. Tight gas basins, Devonian shale, methane from coal seams, and methane from geopressured aquifers are considered. It is concluded that unconventional sources, already providing about 1 Tcf per year, could provide from 3 to 4 Tcf in 1985 and from 6 to 8 Tcf in 1990 (at $1.75 and $3.00 per Mcf, respectively). However, even with these additions to supply, gas supply is projected to remain below 1977 usage levels. (DLC)

  19. Pore-scale mechanisms of gas flow in tight sand reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Silin, D.; Kneafsey, T.J.; Ajo-Franklin, J.B.; Nico, P.

    2010-11-30

    Tight gas sands are unconventional hydrocarbon energy resource storing large volume of natural gas. Microscopy and 3D imaging of reservoir samples at different scales and resolutions provide insights into the coaredo not significantly smaller in size than conventional sandstones, the extremely dense grain packing makes the pore space tortuous, and the porosity is small. In some cases the inter-granular void space is presented by micron-scale slits, whose geometry requires imaging at submicron resolutions. Maximal Inscribed Spheres computations simulate different scenarios of capillary-equilibrium two-phase fluid displacement. For tight sands, the simulations predict an unusually low wetting fluid saturation threshold, at which the non-wetting phase becomes disconnected. Flow simulations in combination with Maximal Inscribed Spheres computations evaluate relative permeability curves. The computations show that at the threshold saturation, when the nonwetting fluid becomes disconnected, the flow of both fluids is practically blocked. The nonwetting phase is immobile due to the disconnectedness, while the permeability to the wetting phase remains essentially equal to zero due to the pore space geometry. This observation explains the Permeability Jail, which was defined earlier by others. The gas is trapped by capillarity, and the brine is immobile due to the dynamic effects. At the same time, in drainage, simulations predict that the mobility of at least one of the fluids is greater than zero at all saturations. A pore-scale model of gas condensate dropout predicts the rate to be proportional to the scalar product of the fluid velocity and pressure gradient. The narrowest constriction in the flow path is subject to the highest rate of condensation. The pore-scale model naturally upscales to the Panfilov's Darcy-scale model, which implies that the condensate dropout rate is proportional to the pressure gradient squared. Pressure gradient is the greatest near the

  20. Assessment of environmental health and safety issues associated with the commercialization of unconventional gas recovery: Tight Western Sands

    Energy Technology Data Exchange (ETDEWEB)

    Riedel, E.F.; Cowan, C.E.; McLaughlin, T.J.

    1980-02-01

    Results of a study to identify and evaluate potential public health and safety problems and the potential environmental impacts from recovery of natural gas from Tight Western Sands are reported. A brief discussion of economic and technical constraints to development of this resource is also presented to place the environmental and safety issues in perspective. A description of the resource base, recovery techniques, and possible environmental effects associated with tight gas sands is presented.

  1. ADVANCED FRACTURING TECHNOLOGY FOR TIGHT GAS: AN EAST TEXAS FIELD DEMONSTRATION

    Energy Technology Data Exchange (ETDEWEB)

    Mukul M. Sharma

    2005-03-01

    The primary objective of this research was to improve completion and fracturing practices in gas reservoirs in marginal plays in the continental United States. The Bossier Play in East Texas, a very active tight gas play, was chosen as the site to develop and test the new strategies for completion and fracturing. Figure 1 provides a general location map for the Dowdy Ranch Field, where the wells involved in this study are located. The Bossier and other tight gas formations in the continental Unites States are marginal plays in that they become uneconomical at gas prices below $2.00 MCF. It was, therefore, imperative that completion and fracturing practices be optimized so that these gas wells remain economically attractive. The economic viability of this play is strongly dependent on the cost and effectiveness of the hydraulic fracturing used in its well completions. Water-fracs consisting of proppant pumped with un-gelled fluid is the type of stimulation used in many low permeability reservoirs in East Texas and throughout the United States. The use of low viscosity Newtonian fluids allows the creation of long narrow fractures in the reservoir, without the excessive height growth that is often seen with cross-linked fluids. These low viscosity fluids have poor proppant transport properties. Pressure transient tests run on several wells that have been water-fractured indicate a long effective fracture length with very low fracture conductivity even when large amounts of proppant are placed in the formation. A modification to the water-frac stimulation design was needed to transport proppant farther out into the fracture. This requires suspending the proppant until the fracture closes without generating excessive fracture height. A review of fracture diagnostic data collected from various wells in different areas (for conventional gel and water-fracs) suggests that effective propped lengths for the fracture treatments are sometimes significantly shorter than those

  2. The experimental modeling of gas percolation mechanisms in a coal-measure tight sandstone reservoir: A case study on the coal-measure tight sandstone gas in the Upper Triassic Xujiahe Formation, Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Shizhen Tao

    2016-12-01

    Full Text Available Tight sandstone gas from coal-measure source rock is widespread in China, and it is represented by the Xujiahe Formation of the Sichuan Basin and the Upper Paleozoic of the Ordos Basin. It is affected by planar evaporative hydrocarbon expulsion of coal-measure source rock and the gentle structural background; hydrodynamics and buoyancy play a limited role in the gas migration-accumulation in tight sandstone. Under the conditions of low permeability and speed, non-Darcy flow is quite apparent, it gives rise to gas-water mixed gas zone. In the gas displacing water experiment, the shape of percolation flow curve is mainly influenced by core permeability. The lower the permeability, the higher the starting pressure gradient as well as the more evident the non-Darcy phenomenon will be. In the gas displacing water experiment of tight sandstone, the maximum gas saturation of the core is generally less than 50% (ranging from 30% to 40% and averaging at 38%; it is similar to the actual gas saturation of the gas zone in the subsurface core. The gas saturation and permeability of the core have a logarithm correlation with a correlation coefficient of 0.8915. In the single-phase flow of tight sandstone gas, low-velocity non-Darcy percolation is apparent; the initial flow velocity (Vd exists due to the slippage effect of gas flow. The shape of percolation flow curve of a single-phase gas is primarily controlled by core permeability and confining pressure; the lower the permeability or the higher the confining pressure, the higher the starting pressure (0.02–0.08 MPa/cm, whereas, the higher the quasi-initial flow speed, the longer the nonlinear section and the more obvious the non-Darcy flow will be. The tight sandstone gas seepage mechanism study shows that the lower the reservoir permeability, the higher the starting pressure and the slower the flow velocity will be, this results in the low efficiency of natural gas migration and accumulation as well as

  3. Design of the ATLAS New Small Wheel Gas Leak Tightness Station for the Micromegas Detector Modules

    CERN Document Server

    Gazis, Evangelos; The ATLAS collaboration

    2017-01-01

    In this work we describe advanced data processing and analysis techniques intended to be used in the gas tightness station at CERN for Quality Assurance and Quality Control of the New Small Wheel Micromegas Quadruplets. We combine two methods: a conventional one based on the Pressure Decay Rate and an alternative-novel one, based on the Flow Rate Loss. A prototype setup has been developed based on a Lock-in Amplifier device and should be operated in conjunction with the gas leak test via the Flow Rate Loss. Both methods have been tested by using emulated leak branches based on specific thin medical needles. The semi-automatic data acquisition, monitoring and processing system is presented also in this work while a more sophisticated environment based on the WinCC-OA SCADA is under development.

  4. Delaying the effect of an aluminum carbide drying agent in a tight gas reservoir

    Directory of Open Access Journals (Sweden)

    Liehui Zhang

    2018-03-01

    Full Text Available Water block damage is the core problem in damage to tight gas reservoirs, and the main obstacle to developing these reservoirs. When an ionic carbide (aluminum carbide: Al4C3 drying agent is injected into the reservoir, the water is quickly gasified through a drying treatment to improve the seepage capacity of the gas and the recovery rate of the reservoir. However, under high temperatures and high pressure (HTHP conditions, it is easy to lose the reactivity due to the high activity of the drying agent, thus preventing the drying effect. In this paper, in order to delay the reaction starting time of the Al4C3 in HTHP conditions with water-cut, a surface modification of aluminum carbide was carried out by using absolute ethyl as the reaction media and polyvinylpyrrolidone (PVP as a modifier under the reaction of an initiator AIBN. The modified Al4C3 was characterized by SEM, TEM, FTIR, and other detection methods. In addition, a gas evolution experiment compared the starting time of the reaction between unmodified aluminum carbide and formation water to the starting time of the reaction between modified aluminum carbide and formation water. Results show that this method can successfully modify the drying agent and effectively block the reaction activity of the drying agent. Meanwhile, gas production in the process of drying and the consumption of formation water are obviously reduced, which can effectively delay the reaction starting time by 6-8 minutes.

  5. Unconventional gas experience at El Paso Production Company : tapping into deep, tight gas and coalbed methane

    International Nuclear Information System (INIS)

    Bartley, R.L.

    2003-01-01

    The current conditions in the natural gas industry were reviewed, from the excellent current and projected energy prices to low activity and rig count. Various graphs were presented, depicting total proved dry gas reserves and annual production over time for the Gulf of Mexico, including its continental shelf, the Texas coastal plains, and the United States lower 48. Offshore growth of unconventional gas was also displayed. The key elements of the strategy were also discussed. These included: (1) earnings driven, (2) superior science, (3) innovative application of technology, (4) ability to act quickly and decisively, (5) leadership, management, and professional development, and (6) achieve learning curve economics. The core competencies were outlined along with recent discoveries in South Texas and the Upper Gulf Coast. figs

  6. Design and Implementation of Energized Fracture Treatment in Tight Gas Sands

    Energy Technology Data Exchange (ETDEWEB)

    Mukul Sharma; Kyle Friehauf

    2009-12-31

    , the minimum CO{sub 2} gas quality (volume % of gas) recommended is 30% for moderate differences between fracture and reservoir pressures (2900 psi reservoir, 5300 psi fracture). The minimum quality is reduced to 20% when the difference between pressures is larger, resulting in additional gas expansion in the invaded zone. Inlet fluid temperature, flow rate, and base viscosity did not have a large impact on fracture production. Finally, every stage of the fracturing treatment should be energized with a gas component to ensure high gas saturation in the invaded zone. A second, more general, sensitivity study was conducted. Simulations show that CO{sub 2} outperforms N{sub 2} as a fluid component because it has higher solubility in water at fracturing temperatures and pressures. In fact, all gas components with higher solubility in water will increase the fluid's ability to reduce damage in the invaded zone. Adding methanol to the fracturing solution can increase the solubility of CO{sub 2}. N{sub 2} should only be used if the gas leaks-off either during the creation of the fracture or during closure, resulting in gas going into the invaded zone. Experimental data is needed to determine if the gas phase leaks-off during the creation of the fracture. Simulations show that the bubbles in a fluid traveling across the face of a porous medium are not likely to attach to the surface of the rock, the filter cake, or penetrate far into the porous medium. In summary, this research has created the first compositional fracturing simulator, a useful tool to aid in energized fracture design. We have made several important and original conclusions about the best practices when using energized fluids in tight gas sands. The models and tools presented here may be used in the future to predict behavior of any multi-phase or multi-component fracturing fluid system.

  7. The RealGas and RealGasH2O options of the TOUGH+ code for the simulation of coupled fluid and heat flow in tight/shale gas systems

    Science.gov (United States)

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas. The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and sh...

  8. STELLAR NUCLEI AND INNER POLAR DISKS IN LENTICULAR GALAXIES

    Energy Technology Data Exchange (ETDEWEB)

    Sil’chenko, Olga K., E-mail: olga@sai.msu.su [Sternberg Astronomical Institute, M.V. Lomonosov Moscow State University, Moscow, 119992 (Russian Federation); Isaac Newton Institute, Chile, Moscow Branch (Chile)

    2016-09-01

    I analyze statistics of the stellar population properties for stellar nuclei and bulges of nearby lenticular galaxies in different environments by using panoramic spectral data of the integral-field spectrograph SAURON retrieved from the open archive of the Isaac Newton Group. I also estimate the fraction of nearby lenticular galaxies having inner polar gaseous disks by exploring the volume-limited sample of early-type galaxies of the ATLAS-3D survey. By inspecting the two-dimensional velocity fields of the stellar and gaseous components with the running tilted-ring technique, I have found seven new cases of inner polar disks. Together with those, the frequency of inner polar disks in nearby S0 galaxies reaches 10%, which is much higher than the frequency of large-scale polar rings. Interestingly, the properties of the nuclear stellar populations in the inner polar ring hosts are statistically the same as those in the whole S0 sample, implying similar histories of multiple gas-accretion events from various directions.

  9. STELLAR NUCLEI AND INNER POLAR DISKS IN LENTICULAR GALAXIES

    International Nuclear Information System (INIS)

    Sil’chenko, Olga K.

    2016-01-01

    I analyze statistics of the stellar population properties for stellar nuclei and bulges of nearby lenticular galaxies in different environments by using panoramic spectral data of the integral-field spectrograph SAURON retrieved from the open archive of the Isaac Newton Group. I also estimate the fraction of nearby lenticular galaxies having inner polar gaseous disks by exploring the volume-limited sample of early-type galaxies of the ATLAS-3D survey. By inspecting the two-dimensional velocity fields of the stellar and gaseous components with the running tilted-ring technique, I have found seven new cases of inner polar disks. Together with those, the frequency of inner polar disks in nearby S0 galaxies reaches 10%, which is much higher than the frequency of large-scale polar rings. Interestingly, the properties of the nuclear stellar populations in the inner polar ring hosts are statistically the same as those in the whole S0 sample, implying similar histories of multiple gas-accretion events from various directions.

  10. Stability of Fluorosurfactant Adsorption on Mineral Surface for Water Removal in Tight Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Lijun You

    2015-01-01

    Full Text Available Long-term effectiveness of rock wettability alteration for water removal during gas production from tight reservoir depends on the surfactant adsorption on the pore surface of a reservoir. This paper selected typical cationic fluorosurfactant FW-134 as an example and took advantage of Fourier transform infrared spectroscopy (FTIR, X-ray photoelectron spectroscopy (XPS, and atomic force microscope (AFM to investigate its adsorption stability on the rock mineral surface under the oscillation condition at high temperature for a long time. The experimental results indicate that the F element content on the sample surface increases obviously, the surface structure of fluorine-carbonization also undergoes a significant change, and the fluorine surfactant exhibits a good interfacial modification and wettability alteration ability due to its adsorption on the pore surface transforming the chemical structure of the original surface. The adsorption increases indistinctly with the concentration of over 0.05% due to a single layer adsorption structure and is mainly electrostatic adsorption because the chemical bonding between the fluorosurfactant and the rock mineral surface, the hydrogen bonding, is weak and inconspicuous.

  11. Genetic Types and Source of the Upper Paleozoic Tight Gas in the Hangjinqi Area, Northern Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Xiaoqi Wu

    2017-01-01

    Full Text Available The molecular and stable isotopic compositions of the Upper Paleozoic tight gas in the Hangjinqi area in northern Ordos Basin were investigated to study the geochemical characteristics. The tight gas is mainly wet with the dryness coefficient (C1/C1–5 of 0.853–0.951, and δ13C1 and δ2H-C1 values are ranging from -36.2‰ to -32.0‰ and from -199‰ to -174‰, respectively, with generally positive carbon and hydrogen isotopic series. Identification of gas origin indicates that tight gas is mainly coal-type gas, and it has been affected by mixing of oil-type gas in the wells from the Shilijiahan and Gongkahan zones adjacent to the Wulanjilinmiao and Borjianghaizi faults. Gas-source correlation indicates that coal-type gas in the Shiguhao zone displays distal-source accumulation. It was mainly derived from the coal-measure source rocks in the Upper Carboniferous Taiyuan Formation (C3t and Lower Permian Shanxi Formation (P1s, probably with a minor contribution from P1s coal measures from in situ Shiguhao zone. Natural gas in the Shilijiahan and Gongkahan zones mainly displays near-source accumulation. The coal-type gas component was derived from in situ C3t-P1s source rocks, whereas the oil-type gas component might be derived from the carbonate rocks in the Lower Ordovician Majiagou Formation (O1m.

  12. Challenges to and countermeasures for the production stabilization of tight sandstone gas reservoirs of the Sulige Gasfield, Ordos Basin

    Directory of Open Access Journals (Sweden)

    Tao Lu

    2015-10-01

    Full Text Available With the grade of hydrocarbon resources becoming poorer, tight sandstone gas reservoirs may serve as the key to the enhancement of both reserves and productivity. Accordingly, high efficient and sustainable development of the large and over-large tight sandstone reservoirs is very important. However, currently, there is no effective method available for macro-analysis. Based on the latest research findings from the Sulige Gasfield, the largest onshore tight sandstone gas reservoir in China, studies were conducted in five aspects, i.e. reserve scale, development scale, dynamic reserve evaluation, rules in production declines of gasfields and undeveloped resource evaluation, to identify challenges to the production stabilization of gas reservoirs. In addition, key evidences and constraints for the solutions to the difficulties in production stabilization were proposed to provide necessary technical supports for high-efficient development in later stages. Research results show that the major challenges to production stabilization include seven aspects, such as low development induced by improper allocation of well patterns, uneven declines in productivity induced by specific features of reservoir formations and fluids, difficulties in the development of some reserves due to complex gas/water correlation, and differences in production performances by using different production techniques. Finally, guided by the development principles of “promoting productivity by using innovative technologies in different spaces and time”, 13 key technologies, such as comprehensive optimization of development well patterns, multi-dimensional matrix for gas well management and “positive” water discharging and gas production technologies, were proposed to further prolong peak production time and enhance the recovery rates of tight gas reservoirs.

  13. Study of the sealing performance of tubing adapters in gas-tight deep-sea water sampler

    Directory of Open Access Journals (Sweden)

    Haocai Huang

    2014-09-01

    Full Text Available Tubing adapter is a key connection device in Gas-Tight Deep-Sea Water Sampler (GTWS. The sealing performance of the tubing adapter directly affects the GTWS's overall gas tightness. Tubing adapters with good sealing performance can ensure the transmission of seawater samples without gas leakage and can be repeatedly used. However, the sealing performance of tubing adapters made of different materials was not studied sufficiently. With the research discussed in this paper, the materials match schemes of the tubing adapters were proposed. With non-linear finite element contact analysis and sea trials in the South China Sea, it is expected that the recommended materials match schemes not only meet the requirements of tubing adapters’ sealing performance but also provide the feasible options for the following research on tubing adapters in GTWS.

  14. Petrophysical Analysis and Geographic Information System for San Juan Basin Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Martha Cather; Robert Lee; Robert Balch; Tom Engler; Roger Ruan; Shaojie Ma

    2008-10-01

    The primary goal of this project is to increase the availability and ease of access to critical data on the Mesaverde and Dakota tight gas reservoirs of the San Juan Basin. Secondary goals include tuning well log interpretations through integration of core, water chemistry and production analysis data to help identify bypassed pay zones; increased knowledge of permeability ratios and how they affect well drainage and thus infill drilling plans; improved time-depth correlations through regional mapping of sonic logs; and improved understanding of the variability of formation waters within the basin through spatial analysis of water chemistry data. The project will collect, integrate, and analyze a variety of petrophysical and well data concerning the Mesaverde and Dakota reservoirs of the San Juan Basin, with particular emphasis on data available in the areas defined as tight gas areas for purpose of FERC. A relational, geo-referenced database (a geographic information system, or GIS) will be created to archive this data. The information will be analyzed using neural networks, kriging, and other statistical interpolation/extrapolation techniques to fine-tune regional well log interpretations, improve pay zone recognition from old logs or cased-hole logs, determine permeability ratios, and also to analyze water chemistries and compatibilities within the study area. This single-phase project will be accomplished through four major tasks: Data Collection, Data Integration, Data Analysis, and User Interface Design. Data will be extracted from existing databases as well as paper records, then cleaned and integrated into a single GIS database. Once the data warehouse is built, several methods of data analysis will be used both to improve pay zone recognition in single wells, and to extrapolate a variety of petrophysical properties on a regional basis. A user interface will provide tools to make the data and results of the study accessible and useful. The final deliverable

  15. 3D Retro-Deformation of the Rotliegend of the `Tight Gas' Area, NGB

    Science.gov (United States)

    Tanner, D. C.; Krawczyk, C.; Oncken, O.; Baunack, C.; Gaupp, R.; Littke, R.; Schubarth-Engelschall, J.; Schwarzer, D.; Solms, M.; Trappe, H.

    2003-04-01

    We have constructed a detailed three-dimensional, geometrical model of the Rotliegend `Tight-Gas' reservoir (10 × 20 km^2) of the North German Basin (NGB) from 3D seismic and borehole data. From this data we have compiled an incremental tectonic history of the area, and retro-deformed faults within the model in time and 3D space. The Top Rotliegend surface lies at depths between 4490 m and 4910 m. We recognise three fault generations in the Rotliegend strata: 1) A NW--SE striking strike-slip fault. 2) N--S striking, dip-slip faults. 3) NE--SW striking faults with late and minor displacements. Vertical throw on all the faults is less than 150 m, but the strike-slip fault is characterized by rapid changes in fault throw along strike, whereas the dip-slip faults are composed of one or more segments which have coalesced over time. We envisage that 1) and 2) faults developed coevally in a transtensive setting. We perform 3D geometrical retro-deformation (i.e. reconstruction of the faulted blocks to the undeformed state) using the inclined-shear method. In this method, the hanging-wall is displaced upon the fault surface along a distinct movement vector, which is determined by the previous tectonic model. Morphology (i.e. curvature) of the fault causes passive deformation of the hanging-wall, which is accommodated by shear along a 3D vector. We present detailed fault analysis, and maps of the quantities and directions of the strain within the Rotliegend strata due to fault movement.

  16. Controlling effect of fractures on gas accumulation and production within the tight sandstone: A case study on the Jurassic Dibei gas reservoir in the eastern part of the Kuqa foreland basin, China

    OpenAIRE

    Lu, Hui; Lu, Xuesong; Fan, Junjia; Zhao, Mengjun; Wei, Hongxing; Zhang, Baoshou; Lu, Yuhong

    2016-01-01

    Using Dibei tight sandstone gas reservoir in the eastern part of the Kuqa foreland basin as an example, this paper discusses tight sandstone reservoir fractures characterization, its effect on storage space and gas flow capacity, and its contribution to gas accumulation, enrichment and production in tight sandstone reservoir by using laser scanning confocal microscope (LSCM) observation, mercury intrusion capillary pressure (MICP) testing, and gas-water two-phase relative permeability testing...

  17. A sampling system for collecting gas-tight time-series hydrothermal fluids

    Science.gov (United States)

    Wu, S.; Yang, C.; Ding, K.

    2012-12-01

    It is known that the hydrothermal venting has temporal variations associated with tectonic and geochemical processes. To date, the methods for long-term monitoring of the seafloor hydrothermal systems are rare. A new sampling system has been designed to be deployed at seafloor for long term to collect gas-tight time-series samples from hydrothermal vents. Based on the modular design principle, the sampling system is currently composed of a control module and six sampling modules, which is convenient to be upgraded by adding more sampling modules if needed. The control module consists of a rechargeable battery pack and a circuit board with functions of sampling control, temperature measurement, data storage and communication. Each sampling module has an independent sampling valve, a valve actuator and a sampling cylinder. The sampling cylinder consists of a sample chamber and an accumulator chamber. Compressed nitrogen gas is used to maintain the sample at in-situ pressure. A prototype of the sampling system has been constructed and tested. First, the instrument was tested in a high-pressure vessel at a pressure of 40 MPa. Six sampling modules were successfully triggered and water samples were collected and kept at in-situ pressure after experiment. Besides, the instrument was field tested at the shallow hydrothermal field near off Kueishantao islet (24°51'N, 121°55'E), which is located offshore of northeastern Taiwan, from May 25 to May 28, 2011. The sampling system worked at an automatic mode. Each sampling module was triggered according to the preset time. Time-series hydrothermal fluids have been collected from a shallow hydrothermal vent with a depth of 16 m. The preliminary tests indicated the success of the design and construction of the prototype of the sampling system. Currently, the sampling system is being upgraded by integration of a DC-DC power conversion and serial-to-Ethernet conversion module, so that it can utilize the continuous power supply and

  18. Analysis of Critical Permeabilty, Capillary Pressure and Electrical Properties for Mesaverde Tight Gas Sandstones from Western U.S. Basins

    Energy Technology Data Exchange (ETDEWEB)

    Alan Byrnes; Robert Cluff; John Webb; John Victorine; Ken Stalder; Daniel Osburn; Andrew Knoderer; Owen Metheny; Troy Hommertzheim; Joshua Byrnes; Daniel Krygowski; Stefani Whittaker

    2008-06-30

    Although prediction of future natural gas supply is complicated by uncertainty in such variables as demand, liquefied natural gas supply price and availability, coalbed methane and gas shale development rate, and pipeline availability, all U.S. Energy Information Administration gas supply estimates to date have predicted that Unconventional gas sources will be the dominant source of U.S. natural gas supply for at least the next two decades (Fig. 1.1; the period of estimation). Among the Unconventional gas supply sources, Tight Gas Sandstones (TGS) will represent 50-70% of the Unconventional gas supply in this time period (Fig. 1.2). Rocky Mountain TGS are estimated to be approximately 70% of the total TGS resource base (USEIA, 2005) and the Mesaverde Group (Mesaverde) sandstones represent the principal gas productive sandstone unit in the largest Western U.S. TGS basins including the basins that are the focus of this study (Washakie, Uinta, Piceance, northern Greater Green River, Wind River, Powder River). Industry assessment of the regional gas resource, projection of future gas supply, and exploration programs require an understanding of reservoir properties and accurate tools for formation evaluation. The goal of this study is to provide petrophysical formation evaluation tools related to relative permeability, capillary pressure, electrical properties and algorithms for wireline log analysis. Detailed and accurate moveable gas-in-place resource assessment is most critical in marginal gas plays and there is need for quantitative tools for definition of limits on gas producibility due to technology and rock physics and for defining water saturation. The results of this study address fundamental questions concerning: (1) gas storage; (2) gas flow; (3) capillary pressure; (4) electrical properties; (5) facies and upscaling issues; (6) wireline log interpretation algorithms; and (7) providing a web-accessible database of advanced rock properties. The following text

  19. A fast simulation tool for evaluation of novel well stimulation techniques for tight gas reservoirs

    NARCIS (Netherlands)

    Egberts, P.J.P.; Peters, E.

    2015-01-01

    For stimulation of tight fields, alternatives to hydraulic fracturing based on hydraulic jetting are becoming available. With hydraulic jetting many (10 to 20) laterals can be created in a (sub-) vertical well. The laterals are 100 to 200 m long, typically 4 laterals are applied with a small

  20. Deconstructing bulges in lenticular galaxies using CALIFA

    Science.gov (United States)

    Méndez-Abreu, J.; CALIFA Team

    2015-05-01

    Bulges play a key role in the evolution of disk galaxies and their influence on the fate of lenticular galaxies (S0s) is still more manifest. We present preliminary results on the photometric and kinematic properties of S0 bulges drawn from the CALIFA survey. We find that S0 galaxies usually deviate from their archetypal view of simple systems composed by a bulge and disk structure. In fact, most of S0 galaxies (˜65%) host bars or non-single exponential profiles, making compulsory the use of multi-component photometric decompositions to properly address the bulge properties. We confirm previous results present in the literature showing S0 galaxies as a complete photometric and kinematic sequence of galaxies.

  1. Epidemiology of traumatic lenticular subluxation in India.

    Science.gov (United States)

    Khokhar, Sudarshan; Agrawal, Saurabh; Gupta, Shikha; Gogia, Varun; Agarwal, Tushar

    2014-04-01

    To study the epidemiological and clinical profile of patients with traumatic subluxated lenses at a tertiary care center in India. Ours was a non-comparative descriptive case series. Evaluation of 71 eyes of 71 consecutive patients presenting to the lens clinic over a period of 2 years with traumatic lenticular subluxation was done. Demographic and clinical profile of patients was acquired, followed by a biomicroscopic examination of the cornea, anterior chamber, iris, lens, angles, zonules, anterior vitreous and fundus. Most of the patients were adolescents and belonged to lower socioeconomic status. The mean time lag before presenting was 33.6 months (range 5 days to 40 years) and mean visual acuity in the affected eyes was 1.67 + 0.56 logMAR. Blunt trauma (63/71) was nine times more common than penetrating trauma in the etiology of manifest subluxation. Injury while playing accounted for the highest rate of injury; sports-related injury with a gulli danda or a cricket bat and ball were the most common mode of blunt trauma while bow and arrow injury was the commonest cause of injury in the penetrating trauma subgroup. Cataract was the most frequent ocular association (53.5 %). All eyes had broken zonules and most presented with inferior subluxation (46 %). Traumatic lenticular subluxation, a unilateral cause of zonulolysis usually occurs while playing with a gulli danda, bow and arrow, or cricket bat and ball in Northern India. It is a major cause of severe visual loss and a modification in risk factors is mandatory to decrease ocular morbidity from trauma.

  2. Development of a data-driven forecasting tool for hydraulically fractured, horizontal wells in tight-gas sands

    Science.gov (United States)

    Kulga, B.; Artun, E.; Ertekin, T.

    2017-06-01

    Tight-gas sand reservoirs are considered to be one of the major unconventional resources. Due to the strong heterogeneity and very low permeability of the formation, and the complexity of well trajectories with multiple hydraulic fractures; there are challenges associated with performance forecasting and optimum exploitation of these resources using conventional modeling approaches. In this study, it is aimed to develop a data-driven forecasting tool for tight-gas sands, which are based on artificial neural networks that can complement the physics-driven modeling approach, namely numerical-simulation models. The tool is designed to predict the horizontal-well performance as a proxy to the numerical model, once the initial conditions, operational parameters, reservoir/hydraulic-fracture characteristics are provided. The data-driven model, that the forecasting tool is based on, is validated with blind cases by estimating the cumulative gas production after 10 years with an average error of 3.2%. A graphical-user-interface application is developed that allows the practicing engineer to use the developed tool in a practical manner by visualizing estimated performance for a given reservoir within a fraction of a second. Practicality of the tool is demonstrated with a case study for the Williams Fork Formation by assessing the performance of various well designs and by incorporating known uncertainties through Monte Carlo simulation. P10, P50 and P90 estimates of the horizontal-well performance are quickly obtained within acceptable accuracy levels.

  3. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface ground water: background, base cases, shallow reservoirs, short-term gas and water transport

    Science.gov (United States)

    Researchers examined gas and water transport between a deep tight shale gas reservoir and a shallow overlying aquifer in the two years following hydraulic fracturing, assuming a pre-existing connecting pathway.

  4. Numerical Modeling of Methane Leakage from a Faulty Natural Gas Well into Fractured Tight Formations.

    Science.gov (United States)

    Moortgat, Joachim; Schwartz, Franklin W; Darrah, Thomas H

    2018-03-01

    Horizontal drilling and hydraulic fracturing have enabled hydrocarbon recovery from unconventional reservoirs, but led to natural gas contamination of shallow groundwaters. We describe and apply numerical models of gas-phase migration associated with leaking natural gas wells. Three leakage scenarios are simulated: (1) high-pressure natural gas pulse released into a fractured aquifer; (2) continuous slow leakage into a tilted fractured formation; and (3) continuous slow leakage into an unfractured aquifer with fluvial channels, to facilitate a generalized evaluation of natural gas transport from faulty natural gas wells. High-pressure pulses of gas leakage into sparsely fractured media are needed to produce the extensive and rapid lateral spreading of free gas previously observed in field studies. Transport in fractures explains how methane can travel vastly different distances and directions laterally away from a leaking well, which leads to variable levels of methane contamination in nearby groundwater wells. Lower rates of methane leakage (≤1 Mcf/day) produce shorter length scales of gas transport than determined by the high-pressure scenario or field studies, unless aquifers have low vertical permeabilities (≤1 millidarcy) and fractures and bedding planes have sufficient tilt (∼10°) to allow a lateral buoyancy component. Similarly, in fractured rock aquifers or where permeability is controlled by channelized fluvial deposits, lateral flow is not sufficiently developed to explain fast-developing gas contamination (0-3 months) or large length scales (∼1 km) documented in field studies. Thus, current efforts to evaluate the frequency, mechanism, and impacts of natural gas leakage from faulty natural gas wells likely underestimate contributions from small-volume, low-pressure leakage events. © 2018, National Ground Water Association.

  5. Energy Return on Energy Invested for Tight Gas Wells in the Appalachian Basin, United States of America

    Directory of Open Access Journals (Sweden)

    Bryan Sell

    2011-10-01

    Full Text Available The energy cost of drilling a natural gas well has never been publicly addressed in terms of the actual fuels and energy required to generate the physical materials consumed in construction. Part of the reason for this is that drilling practices are typically regarded as proprietary; hence the required information is difficult to obtain. We propose that conventional tight gas wells that have marginal production characteristics provide a baseline for energy return on energy invested (EROI analyses. To develop an understanding of baseline energy requirements for natural gas extraction, we examined production from a mature shallow gas field composed of vertical wells in Pennsylvania and materials used in the drilling and completion of individual wells. The data were derived from state maintained databases and reports, personal experience as a production geologist, personal interviews with industry representatives, and literature sources. We examined only the “upstream” energy cost of providing gas and provide a minimal estimate of energy cost because of uncertainty about some inputs. Of the materials examined, steel and diesel fuel accounted for more than two-thirds of the energy cost for well construction. Average energy cost per foot for a tight gas well in Indiana County is 0.59 GJ per foot. Available production data for this natural gas play was used to calculate energy return on energy invested ratios (EROI between 67:1 and 120:1, which depends mostly on the amount of materials consumed, drilling time, and highly variable production. Accounting for such inputs as chemicals used in well treatment, materials used to construct drill bits and drill pipe, post-gathering pipeline construction, and well completion maintenance would decrease EROI by an unknown amount. This study provides energy constraints at the single-well scale for the energy requirements for drilling in geologically simple systems. The energy and monetary costs of wells from

  6. Advancing New 3D Seismic Interpretation Methods for Exploration and Development of Fractured Tight Gas Reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    James Reeves

    2005-01-31

    In a study funded by the U.S. Department of Energy and GeoSpectrum, Inc., new P-wave 3D seismic interpretation methods to characterize fractured gas reservoirs are developed. A data driven exploratory approach is used to determine empirical relationships for reservoir properties. Fractures are predicted using seismic lineament mapping through a series of horizon and time slices in the reservoir zone. A seismic lineament is a linear feature seen in a slice through the seismic volume that has negligible vertical offset. We interpret that in regions of high seismic lineament density there is a greater likelihood of fractured reservoir. Seismic AVO attributes are developed to map brittle reservoir rock (low clay) and gas content. Brittle rocks are interpreted to be more fractured when seismic lineaments are present. The most important attribute developed in this study is the gas sensitive phase gradient (a new AVO attribute), as reservoir fractures may provide a plumbing system for both water and gas. Success is obtained when economic gas and oil discoveries are found. In a gas field previously plagued with poor drilling results, four new wells were spotted using the new methodology and recently drilled. The wells have estimated best of 12-months production indicators of 2106, 1652, 941, and 227 MCFGPD. The latter well was drilled in a region of swarming seismic lineaments but has poor gas sensitive phase gradient (AVO) and clay volume attributes. GeoSpectrum advised the unit operators that this location did not appear to have significant Lower Dakota gas before the well was drilled. The other three wells are considered good wells in this part of the basin and among the best wells in the area. These new drilling results have nearly doubled the gas production and the value of the field. The interpretation method is ready for commercialization and gas exploration and development. The new technology is adaptable to conventional lower cost 3D seismic surveys.

  7. Coherent soft X-ray high-order harmonics using tight-focusing laser pulses in the gas mixture.

    Science.gov (United States)

    Lu, Faming; Xia, Yuanqin; Zhang, Sheng; Chen, Deying; Zhao, Yang; Liu, Bin

    2014-01-01

    We experimentally study the harmonics from a Xe-He gas mixture using tight-focusing femtosecond laser pulses. The spectrum in the mixed gases exhibits an extended cutoff region from the harmonic H21 to H27. The potential explanation is that the harmonics photons from Xe contribute the electrons of He atoms to transmit into the excited-state. Therefore, the harmonics are emitted from He atoms easily. Furthermore, we show that there are the suppressed harmonics H15 and H17 in the mixed gases. The underlying mechanism is the destructive interference between harmonics generated from different atoms. Our results indicate that HHG from Xe-He gas mixture is an efficient method of obtaining the coherent soft X-ray source.

  8. Remote sensing of fugitive methane emissions from oil and gas production in North American tight geologic formations

    Science.gov (United States)

    Schneising, Oliver; Burrows, John P.; Dickerson, Russell R.; Buchwitz, Michael; Reuter, Maximilian; Bovensmann, Heinrich

    2014-10-01

    In the past decade, there has been a massive growth in the horizontal drilling and hydraulic fracturing of shale gas and tight oil reservoirs to exploit formerly inaccessible or unprofitable energy resources in rock formations with low permeability. In North America, these unconventional domestic sources of natural gas and oil provide an opportunity to achieve energy self-sufficiency and to reduce greenhouse gas emissions when displacing coal as a source of energy in power plants. However, fugitive methane emissions in the production process may counter the benefit over coal with respect to climate change and therefore need to be well quantified. Here we demonstrate that positive methane anomalies associated with the oil and gas industries can be detected from space and that corresponding regional emissions can be constrained using satellite observations. On the basis of a mass-balance approach, we estimate that methane emissions for two of the fastest growing production regions in the United States, the Bakken and Eagle Ford formations, have increased by 990 ± 650 ktCH4 yr-1 and 530 ± 330 ktCH4 yr-1 between the periods 2006-2008 and 2009-2011. Relative to the respective increases in oil and gas production, these emission estimates correspond to leakages of 10.1% ± 7.3% and 9.1% ± 6.2% in terms of energy content, calling immediate climate benefit into question and indicating that current inventories likely underestimate the fugitive emissions from Bakken and Eagle Ford.

  9. A new method in predicting productivity of multi-stage fractured horizontal well in tight gas reservoirs

    Directory of Open Access Journals (Sweden)

    Yunsheng Wei

    2016-10-01

    Full Text Available The generally accomplished technique for horizontal wells in tight gas reservoirs is by multi-stage hydraulic fracturing, not to mention, the flow characteristics of a horizontal well with multiple transverse fractures are very intricate. Conventional methods, well as an evaluation unit, are difficult to accurately predict production capacity of each fracture and productivity differences between wells with a different number of fractures. Thus, a single fracture sets the minimum evaluation unit, matrix, fractures, and lateral wellbore model that are then combined integrally to approximate horizontal well with multiple transverse hydraulic fractures in tight gas reservoirs. This paper presents a new semi-analytical methodology for predicting the production capacity of a horizontal well with multiple transverse hydraulic fractures in tight gas reservoirs. Firstly, a mathematical flow model used as a medium, which is disturbed by finite conductivity vertical fractures and rectangular shaped boundaries, is established and explained by the Fourier integral transform. Then the idea of a single stage fracture analysis is incorporated to establish linear flow model within a single fracture with a variable rate. The Fredholm integral numerical solution is applicable for the fracture conductivity function. Finally, the pipe flow model along the lateral wellbore is adapted to couple multi-stages fracture mathematical models, and the equation group of predicting productivity of a multi-stage fractured horizontal well. The whole flow process from the matrix to bottom-hole and production interference between adjacent fractures is also established. Meanwhile, the corresponding iterative algorithm of the equations is given. In this case analysis, the productions of each well and fracture are calculated under the different bottom-hole flowing pressure, and this method also contributes to obtaining the distribution of pressure drop and production for every

  10. Rock matrix and fracture analysis of flow in western tight gas sands

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, N.R.; Brower, K.R.; Kilmer, N.H.; Ward, J.S.

    1984-01-01

    The presence of natural fractures is often cited as a key factor in gas production for both fractured and unfractured wells. Numerous vertical fractures have been found in cores recovered in the Multi-Well Project. The cores show that by far the majority of fractures become filled with calcite cement. However, calcite-filled fractures are not necessarily a seal to gas flow. As part of this project, flow measurements are being made along and across selected fractured samples as a function of overburden pressure for a minimum of five core samples. Comparative measurements will be made on unfractured neighboring cores. Permeability measurements will be made at a minimum of four levels of water saturation for each of at least six samples to assess the effect of water content on permeabilities in fractured systems. The effects of chemical treatments on mineralized fractures will be studied to assess whether such treatments lead to permeability enhancement of formation damage. Permeability to gas will be measured at various levels of water saturation established by equilibration of core samples in humidity chambers. Electrical resistivity at various levels of water saturations and confining pressures will also be measured. Special attention will be given to water distribution within the rock pore space. circumstances under which water can act to inhibit gas production and the pressure differences necessary to overcome capillary seals formed by water will also be investigated. Capillary pressure measurements will be made using a high-speed centrifuge.

  11. Performance evaluation on water-producing gas wells based on gas & water relative permeability curves: A case study of tight sandstone gas reservoirs in the Sulige gas field, Ordos Basin

    Directory of Open Access Journals (Sweden)

    Yuegang Li

    2016-01-01

    Full Text Available An outstanding issue in the oil and gas industry is how to evaluate quantitatively the influences of water production on production performance of gas wells. Based on gas–water flow theories, therefore, a new method was proposed in this paper to evaluate quantitatively the production performance of water-producing gas wells by using gas & water relative permeability curves after a comparative study was conducted thoroughly. In this way, quantitative evaluation was performed on production capacity, gas production, ultimate cumulative gas production and recovery factor of water-producing gas wells. Then, a case study was carried out of the tight sandstone gas reservoirs with strong heterogeneity in the Sulige gas field, Ordos Basin. This method was verified in terms of practicability and reliability through a large amount of calculation based on the actual production performance data of various gas wells with different volumes of water produced. Finally, empirical formula and charts were established for water-producing gas wells in this field to quantitatively evaluate their production capacity, gas production, ultimate cumulative gas production and recovery factor in the conditions of different water–gas ratios. These formula and charts provide technical support for the field application and dissemination of the method. Study results show that water production is serious in the west of this field with water–gas ratio varying in a large range. If the average water–gas ratio is 1.0 (or 2.0 m3/104 m3, production capacity, cumulative gas production and recovery factor of gas wells will be respectively 24.4% (or 40.2%, 24.4% (or 40.2% and 17.4% (or 33.2%.

  12. High-Precision Spectral Decomposition Method Based on VMD/CWT/FWEO for Hydrocarbon Detection in Tight Sandstone Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Hui Chen

    2017-07-01

    Full Text Available Seismic time-frequency analysis methods can be used for hydrocarbon detection because of the phenomena of energy and abnormal attenuation of frequency when the seismic waves travel across reservoirs. A high-resolution method based on variational mode decomposition (VMD, continuous-wavelet transform (CWT and frequency-weighted energy operator (FWEO is proposed for hydrocarbon detection in tight sandstone gas reservoirs. VMD can decompose seismic signals into a set of intrinsic mode functions (IMF in the frequency domain. In order to avoid meaningful frequency loss, the CWT method is used to obtain the time-frequency spectra of the selected IMFs. The energy separation algorithm based on FWEO can improve the resolution of time-frequency spectra and highlight abnormal energy, which is applied to track the instantaneous energy in the time-frequency spectra. The difference between the high-frequency section and low-frequency section acquired by applying the proposed method is utilized to detect hydrocarbons. Applications using the model and field data further demonstrate that the proposed method can effectively detect hydrocarbons in tight sandstone reservoirs, with good anti-noise performance. The newly-proposed method can be used as an analysis tool to detect hydrocarbons.

  13. Damage evaluation on oil-based drill-in fluids for ultra-deep fractured tight sandstone gas reservoirs

    Directory of Open Access Journals (Sweden)

    Jinzhi Zhu

    2017-07-01

    Full Text Available In order to explore the damage mechanisms and improve the method to evaluate and optimize the performance of formation damage control of oil-based drill-in fluids, this paper took an ultra-deep fractured tight gas reservoir in piedmont configuration, located in the Cretaceous Bashijiqike Fm of the Tarim Basin, as an example. First, evaluation experiments were conducted on the filtrate invasion, the dynamic damage of oil-based drill-in fluids and the loading capacity of filter cakes. Meanwhile, the evaluating methods were optimized for the formation damage control effect of oil-based drill-in fluids in laboratory: pre-processing drill-in fluids before grading analysis; using the dynamic damage method to simulate the damage process for evaluating the percentage of regained permeability; and evaluating the loading capacity of filter cakes. The experimental results show that (1 oil phase trapping damage and solid phase invasion are the main formation damage types; (2 the damage degree of filtrate is the strongest on the matrix; and (3 the dynamic damage degree of oil-based drill-in fluids reaches medium strong to strong on fractures and filter cakes show a good sealing capacity for the fractures less than 100 μm. In conclusion, the filter cakes' loading capacity should be first guaranteed, and both percentage of regained permeability and liquid trapping damage degree should be both considered in the oil-based drill-in fluids prepared for those ultra-deep fractured tight sandstone gas reservoirs.

  14. Intricate but tight coupling of spiracular activity and abdominal ventilation during locust discontinuous gas exchange cycles.

    Science.gov (United States)

    Talal, Stav; Gefen, Eran; Ayali, Amir

    2018-03-15

    Discontinuous gas exchange (DGE) is the best studied among insect gas exchange patterns. DGE cycles comprise three phases, which are defined by their spiracular state: closed, flutter and open. However, spiracle status has rarely been monitored directly; rather, it is often assumed based on CO 2 emission traces. In this study, we directly recorded electromyogram (EMG) signals from the closer muscle of the second thoracic spiracle and from abdominal ventilation muscles in a fully intact locust during DGE. Muscular activity was monitored simultaneously with CO 2 emission, under normoxia and under various experimental oxic conditions. Our findings indicate that locust DGE does not correspond well with the commonly described three-phase cycle. We describe unique DGE-related ventilation motor patterns, coupled to spiracular activity. During the open phase, when CO 2 emission rate is highest, the thoracic spiracles do not remain open; rather, they open and close rapidly. This fast spiracle activity coincides with in-phase abdominal ventilation, while alternating with the abdominal spiracle and thus facilitating a unidirectional air flow along the main trachea. A change in the frequency of rhythmic ventilation during the open phase suggests modulation by intra-tracheal CO 2 levels. A second, slow ventilatory movement pattern probably serves to facilitate gas diffusion during spiracle closure. Two flutter-like patterns are described in association with the different types of ventilatory activity. We offer a modified mechanistic model for DGE in actively ventilating insects, incorporating ventilatory behavior and changes in spiracle state. © 2018. Published by The Company of Biologists Ltd.

  15. Impact of Petrophysical Properties on Hydraulic Fracturing and Development in Tight Volcanic Gas Reservoirs

    Directory of Open Access Journals (Sweden)

    Yinghao Shen

    2017-01-01

    Full Text Available The volcanic reservoir is an important kind of unconventional reservoir. The aqueous phase trapping (APT appears because of fracturing fluids filtration. However, APT can be autoremoved for some wells after certain shut-in time. But there is significant distinction for different reservoirs. Experiments were performed to study the petrophysical properties of a volcanic reservoir and the spontaneous imbibition is monitored by nuclear magnetic resonance (NMR and pulse-decay permeability. Results showed that natural cracks appear in the samples as well as high irreducible water saturation. There is a quick decrease of rock permeability once the rock contacts water. The pores filled during spontaneous imbibition are mainly the nanopores from NMR spectra. Full understanding of the mineralogical effect and sample heterogeneity benefits the selection of segments to fracturing. The fast flow-back scheme is applicable in this reservoir to minimize the damage. Because lots of water imbibed into the nanopores, the main flow channels become larger, which are beneficial to the permeability recovery after flow-back of hydraulic fracturing. This is helpful in understanding the APT autoremoval after certain shut-in time. Also, Keeping the appropriate production differential pressure is very important in achieving the long term efficient development of volcanic gas reservoirs.

  16. Vital signs: oil supplies improving but natural gas tight enough to keep prices high

    International Nuclear Information System (INIS)

    Lunan, D.

    2000-01-01

    Canada's 1999 year-end oil reserves were boosted by 2.1 million barrels by the launch of new oil sands mining projects near Fort McMurray and revisions in two existing operations, offsetting a decline of 3.7 per cent in remaining conventional reserves. Total oil reserves at year end stood at some 11.9 billion barrels, up from 9.8 billion barrels a year earlier. Conventional crude reserves dropped to 4.37 billion barrels. Despite the decline, the Canadian Association of Petroleum Producers (CAPP) were encouraged by a 70 per cent replacement rate, on production of 441 million barrels of oil, despite low activity resulting from soft prices in early part of 1999. Production from offshore Newfoundland sites amounted to 38.6 million barrels; remaining reserves in the Hibernia and Terra Nova field are estimated at 868 million barrels. Meanwhile, natural gas reserves slipped by about a trillion cubic feet to about 61 trillion cubic feet, reflecting an 83 per cent replacement rate which, however, represented an improvement from 76 per cent in 1998. Reserves replacement in 2000 is expected to improve over 1999 due to improved prices resulting in increased activity in 2000 which is expected to continue into 2001. Despite improvements in replacement, consumers have much to worry about as far as further consumer price increases are concerned. The situation can be traced back to the summer 2000 storage injection period when supplies normally stored for use in the winter were sold instead, to take advantage of high prices. The injection for storage was reduced due largely to continued strong demand from the US electric power generating sector. This situation will continue, barring a dramatic softening of the US economy

  17. Study on the lower limits of petrophysical parameters of the Upper Paleozoic tight sandstone gas reservoirs in the Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Huiying Cui

    2017-02-01

    Full Text Available There hasn't been a clear understanding of the lower limits of petrophysical parameters of tight sandstone gas reservoirs so far. However, it is an important question directly related to exploration and development strategies. Research methods of the lower limits of petrophysical parameters are reviewed. The new minimum flow pore throat radius method is used to determine the lower limit of flow pore throat radius. The relative permeability curve method, irreducible water saturation method, and testing method, are used to determine the lower limits of porosity, permeability, and gas saturation. After the comprehensive analysis, the lower limits of petrophysical parameters of the Upper Paleozoic tight sandstone gas reservoirs in Ordos Basin are thought as follows: the minimum flow pore throat radius is 0.02 μm, the lower limits of porosity are 3%, the permeability is 0.02 × 10−3 μm2 and the gas saturation is 20%. Besides, the influence of formation pressure on porosity and permeability, the tight sandstone gas filling mechanism, and reservoir characterization petrophysical parameters of tight sandstone reservoirs are further discussed.

  18. Controlling effect of fractures on gas accumulation and production within the tight sandstone: A case study on the Jurassic Dibei gas reservoir in the eastern part of the Kuqa foreland basin, China

    Directory of Open Access Journals (Sweden)

    Hui Lu

    2016-02-01

    Full Text Available Using Dibei tight sandstone gas reservoir in the eastern part of the Kuqa foreland basin as an example, this paper discusses tight sandstone reservoir fractures characterization, its effect on storage space and gas flow capacity, and its contribution to gas accumulation, enrichment and production in tight sandstone reservoir by using laser scanning confocal microscope (LSCM observation, mercury intrusion capillary pressure (MICP testing, and gas-water two-phase relative permeability testing. The statistics of laser scanning confocal microscopy observation showed that the microstructural fractures width in the Dibei gas reservoir was mainly 8–25 μm, and the associated micro-fractures width was mainly 4–10 μm. Additionally, the throat radius was mainly 1–4 μm. The fractures width was significantly wider than the throat radius that served as the main channel of in gas flow. In addition, it illustrated that the samples with developed fractures became easier for gas to flow under equal porosity condition, because of lower expulsion pressure, higher mercury injection saturation, and increased gas relative permeability based on the physical simulation experiment of gas charging into core samples with saturated water, mercury injection and gas-water two-phase permeability experiments. Furthermore, it had been concluded that the fractures control tight gas in the following aspects: (1 Fractures play a significant role in reservoir property improvement. The isolated pores were linked by the fractures to form connective reservoir spaces, and dissolution is prone to occur along the fractures forming new pores. The fractures with bigger width are reservoir space as well. (2 Fractures increased fluid flow capacity because it decreased the starting pressure gradient, and it increased gas effective permeability. Thus, fractures improved the gas injection efficiency as well as gas production. (3 Fractures that developed in different time and spatial

  19. Design philosophy and practice of asymmetrical 3D fracturing and random fracturing: A case study of tight sand gas reservoirs in western Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Jianchun Guo

    2015-03-01

    Full Text Available At present two technical models are commonly taken in tight gas reservoir stimulation: conventional massive fracturing and SRV fracturing, but how to select a suitable fracturing model suitable for reservoir characteristics is still a question waiting to be answered. In this paper, based on the analysis of geological characteristics and seepage mechanism of tight gas and shale gas reservoirs, the differences between stimulation philosophy of tight gas reservoirs and shale reservoirs are elucidated, and the concept that a suitable stimulation model should be selected based on reservoir geological characteristics and seepage mechanism aiming at maximally improving the seepage capability of a reservoir. Based on this concept, two fracturing design methods were proposed for two tight gas reservoirs in western Sichuan Basin: asymmetrical 3D fracturing design (A3DF for the middle-shallow Upper Jurassic Penglaizhen Fm stacked reservoirs in which the hydraulic fractures can well match the sand spatial distribution and seepage capability of the reservoirs; SRV fracturing design which can increase fracture randomness in the sandstone and shale laminated reservoirs for the 5th Member of middle-deep Upper Triassic Xujiahe Fm. Compared with that by conventional fracturing, the average production of horizontal wells fractured by A3DF increased by 41%, indicating that A3DF is appropriate for gas reservoir development in the Penglaizhen Fm; meanwhile, the average production per well of the 5th Member of the Xujiahe Fm was 2.25 × 104 m3/d after SRV fracturing, showing that the SRV fracturing is a robust technical means for the development of this reservoir.

  20. Improving the Availability and Delivery of Critical Information for Tight Gas Resource Development in the Appalachian Basin

    Energy Technology Data Exchange (ETDEWEB)

    Mary Behling; Susan Pool; Douglas Patchen; John Harper

    2008-12-31

    To encourage, facilitate and accelerate the development of tight gas reservoirs in the Appalachian basin, the geological surveys in Pennsylvania and West Virginia collected widely dispersed data on five gas plays and formatted these data into a large database that can be accessed by individual well or by play. The database and delivery system that were developed can be applied to any of the 30 gas plays that have been defined in the basin, but for this project, data compilation was restricted to the following: the Mississippian-Devonian Berea/Murrysville sandstone play and the Upper Devonian Venango, Bradford and Elk sandstone plays in Pennsylvania and West Virginia; and the 'Clinton'/Medina sandstone play in northwestern Pennsylvania. In addition, some data were collected on the Tuscarora Sandstone play in West Virginia, which is the lateral equivalent of the Medina Sandstone in Pennsylvania. Modern geophysical logs are the most common and cost-effective tools for evaluating reservoirs. Therefore, all of the well logs in the libraries of the two surveys from wells that had penetrated the key plays were scanned, generating nearly 75,000 scanned e-log files from more than 40,000 wells. A standard file-naming convention for scanned logs was developed, which includes the well API number, log curve type(s) scanned, and the availability of log analyses or half-scale logs. In addition to well logs, other types of documents were scanned, including core data (descriptions, analyses, porosity-permeability cross-plots), figures from relevant chapters of the Atlas of Major Appalachian Gas Plays, selected figures from survey publications, and information from unpublished reports and student theses and dissertations. Monthly and annual production data from 1979 to 2007 for West Virginia wells in these plays are available as well. The final database also includes digitized logs from more than 800 wells, sample descriptions from more than 550 wells, more than 600

  1. The RealGas and RealGasH2O Options of the TOUGH+ Code for the Simulation of Coupled Fluid and Heat Flow in Tight/Shale Gas Systems

    Energy Technology Data Exchange (ETDEWEB)

    Moridis, George; Freeman, Craig

    2013-09-30

    We developed two new EOS additions to the TOUGH+ family of codes, the RealGasH2O and RealGas . The RealGasH2O EOS option describes the non-isothermal two-phase flow of water and a real gas mixture in gas reservoirs, with a particular focus in ultra-tight (such as tight-sand and shale gas) reservoirs. The gas mixture is treated as either a single-pseudo-component having a fixed composition, or as a multicomponent system composed of up to 9 individual real gases. The RealGas option has the same general capabilities, but does not include water, thus describing a single-phase, dry-gas system. In addition to the standard capabilities of all members of the TOUGH+ family of codes (fully-implicit, compositional simulators using both structured and unstructured grids), the capabilities of the two codes include: coupled flow and thermal effects in porous and/or fractured media, real gas behavior, inertial (Klinkenberg) effects, full micro-flow treatment, Darcy and non-Darcy flow through the matrix and fractures of fractured media, single- and multi-component gas sorption onto the grains of the porous media following several isotherm options, discrete and fracture representation, complex matrix-fracture relationships, and porosity-permeability dependence on pressure changes. The two options allow the study of flow and transport of fluids and heat over a wide range of time frames and spatial scales not only in gas reservoirs, but also in problems of geologic storage of greenhouse gas mixtures, and of geothermal reservoirs with multi-component condensable (H2O and CH4) and non-condensable gas mixtures. The codes are verified against available analytical and semi-analytical solutions. Their capabilities are demonstrated in a series of problems of increasing complexity, ranging from isothermal flow in simpler 1D and 2D conventional gas reservoirs, to non-isothermal gas flow in 3D fractured shale gas reservoirs involving 4 types of fractures, micro-flow, non-Darcy flow and gas

  2. Integrated techniques for rapid and highly-efficient development and production of ultra-deep tight sand gas reservoirs of Keshen 8 Block in the Tarim Basin

    Directory of Open Access Journals (Sweden)

    Tongwen Jiang

    2017-01-01

    Full Text Available The unusually ultra-deep and ultra-high-pressure gas reservoirs in the Keshen 8 Block on the Kelasu structural belt of the Tarim Basin are also featured by high temperature, well-developed fault fissures, huge thickness, tight matrix, complex oil–water distribution, etc., which brings about great difficulties to reserves evaluation and further development. In view of this, an overall study was made on the fine description of reservoir fractures and their seepage mechanism, technical problems were being tackled on seismic data processing and interpretation of complex and high & steep structural zones, optimal development design, safe & rapid drilling and completion wells, reservoir stimulation, dynamic monitoring, etc. to promote the development level of such ultra-deep tight gas reservoirs, and 22 complete sets of specific techniques were formulated in the fields of high-efficiency well spacing, safe and fast drilling, recovery enhancement by well completion transformation, efficient development of optimization design, and so on. Through the technical progress and innovative management of integrated exploration & development, reserves evaluation and productivity construction have been completed on the Keshen 8 Block in the last three years of the 12th Five-Year Plan period (2011–2015, as a result, rapid and high-efficiency productivity construction is realized, and a new area is explored in the development of ultra-deep and ultra-high-pressure fractured tight sand gas reservoirs. This study is of great reference to the development of similar gas reservoirs at home and abroad.

  3. Hydraulic fracture model and diagnostics verification at GRI/DOE multi-site projects and tight gas sand program support. Final report, July 28, 1993--February 28, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Schroeder, J.E.

    1997-12-31

    The Mesaverde Group of the Piceance Basin in western Colorado has been a pilot study area for government-sponsored tight gas sand research for over twenty years. Early production experiments included nuclear stimulations and massive hydraulic fracture treatments. This work culminated in the US Department of Energy (DOE)`s Multiwell Experiment (MWX), a field laboratory designed to study the reservoir and production characteristics of low permeability sands. A key feature of MWX was an infrastructure which included several closely spaced wells that allowed detailed characterization of the reservoir through log and core analysis, and well testing. Interference and tracer tests, as well as the use of fracture diagnostics gave further information on stimulation and production characteristics. Thus, the Multiwell Experiment provided a unique opportunity for identifying the factors affecting production from tight gas sand reservoirs. The purpose of this operation was to support the gathering of field data that may be used to resolve the number of unknowns associated with measuring and modeling the dimensions of hydraulic fractures. Using the close-well infrastructure at the Multiwell Site near Rifle, Colorado, this operation focused primarily on the field design and execution of experiments. The data derived from the experiments were gathered and analyzed by DOE team contractors.

  4. Optimization of a development well pattern based on production performance: A case study of the strongly heterogeneous Sulige tight sandstone gas field, Ordos Basin

    Directory of Open Access Journals (Sweden)

    Yuegang Li

    2015-01-01

    Full Text Available As a typical tight sandstone gas field with strong heterogeneity, the Sulige Gas Field in the Ordos Basin faces major challenges in its development because the reservoirs in the gas field are small in effective sand scale, rapid in lithologic change, strong in plane heterogeneity, and poor in connectivity. How to scientifically deploy development wells to improve the recovery is the most important issue for the successful development of this kind of gas fields. Therefore, a well inference analysis was conducted to figure out the impact of well pattern density on the recovery based on the research of many years in gas field development methods and the summary of practical effect. In this paper, we put forward for the first time the concept of inter-well interference probability, and present the relationship between the probability of inter-well interference and well pattern density of the Sulige Gas Field. Then we established a mathematical model for the optimization of development well pattern by combining fine sand anatomy, reservoir engineering, numerical simulation and economic evaluation, and obtained a quantitative relationship between recovery and well pattern density. Furthermore, on the basis of comprehensive analysis, a reasonable development well pattern was designed for the Sulige Gas Field: this well pattern is parallelogram in shape, with a density of 3.1 wells/km2, well spacing of 500 m, and row spacing of 650 m. Development practices have confirmed that this scheme is capable of achieving better economic benefits, producing geological reserves as far as possible and improving the ultimate recovery of such gas fields.

  5. Tight turns

    CERN Multimedia

    Anaïs Schaeffer

    2012-01-01

    The Italian National Institute for Nuclear Physics (INFN) has successfully tested the first model of a new fast-ramping curved dipole magnet. This is great news for CERN, which sees the advance as holding potential for the future of the SPS.   The first model of a new fast-ramping curved dipole magnet being prepared for cryogenic testing at the LASA laboratory (INFN Milano, Italy). On 16 July INFN introduced an innovative dipole magnet. With a length of some 4 metres, it can produce a 4.5 Tesla magnetic field and achieve a tighter bend than ever before (the bending radius has been squeezed to a remarkable 66.7 metres). This new magnet was designed in the first instance for GSI’s SIS300 synchrotron (in Germany), which will require 60 dipoles of this type. "Achieving such a tight bend demanded a major R&D effort," stressed Pasquale Fabbricatore, the spokesman of the INFN collaboration responsible for the magnet’s development. "We had to not o...

  6. Numerical simulation of the environmental impact of hydraulic fracturing of tight/shale gas reservoirs on near-surface groundwater: Background, base cases, shallow reservoirs, short-term gas, and water transport.

    Science.gov (United States)

    Reagan, Matthew T; Moridis, George J; Keen, Noel D; Johnson, Jeffrey N

    2015-04-01

    Hydrocarbon production from unconventional resources and the use of reservoir stimulation techniques, such as hydraulic fracturing, has grown explosively over the last decade. However, concerns have arisen that reservoir stimulation creates significant environmental threats through the creation of permeable pathways connecting the stimulated reservoir with shallower freshwater aquifers, thus resulting in the contamination of potable groundwater by escaping hydrocarbons or other reservoir fluids. This study investigates, by numerical simulation, gas and water transport between a shallow tight-gas reservoir and a shallower overlying freshwater aquifer following hydraulic fracturing operations, if such a connecting pathway has been created. We focus on two general failure scenarios: (1) communication between the reservoir and aquifer via a connecting fracture or fault and (2) communication via a deteriorated, preexisting nearby well. We conclude that the key factors driving short-term transport of gas include high permeability for the connecting pathway and the overall volume of the connecting feature. Production from the reservoir is likely to mitigate release through reduction of available free gas and lowering of reservoir pressure, and not producing may increase the potential for release. We also find that hydrostatic tight-gas reservoirs are unlikely to act as a continuing source of migrating gas, as gas contained within the newly formed hydraulic fracture is the primary source for potential contamination. Such incidents of gas escape are likely to be limited in duration and scope for hydrostatic reservoirs. Reliable field and laboratory data must be acquired to constrain the factors and determine the likelihood of these outcomes. Short-term leakage fractured reservoirs requires high-permeability pathways Production strategy affects the likelihood and magnitude of gas release Gas release is likely short-term, without additional driving forces.

  7. Rock matrix and fracture analysis of flow in western tight gas sands. Quarterly technical progress report, September--December 1984

    Energy Technology Data Exchange (ETDEWEB)

    Morrow, N.R.; Brower, K.R.; Kilmer, N.H.; Ward, J.S.

    1984-12-31

    The presence of natural fractures is often cited as a key factor in gas production for both fractured and unfractured wells. Numerous vertical fractures have been found in cores recovered in the Multi-Well Project. The cores show that by far the majority of fractures become filled with calcite cement. However, calcite-filled fractures are not necessarily a seal to gas flow. As part of this project, flow measurements are being made along and across selected fractured samples as a function of overburden pressure for a minimum of five core samples. Comparative measurements will be made on unfractured neighboring cores. Permeability measurements will be made at a minimum of four levels of water saturation for each of at least six samples to assess the effect of water content on permeabilities in fractured systems. The effects of chemical treatments on mineralized fractures will be studied to assess whether such treatments lead to permeability enhancement of formation damage. Permeability to gas will be measured at various levels of water saturation established by equilibration of core samples in humidity chambers. Electrical resistivity at various levels of water saturations and confining pressures will also be measured. Special attention will be given to water distribution within the rock pore space. circumstances under which water can act to inhibit gas production and the pressure differences necessary to overcome capillary seals formed by water will also be investigated. Capillary pressure measurements will be made using a high-speed centrifuge.

  8. Transformation of a beta gamma hot-cell under air in a tight hot-cell under inert gas

    International Nuclear Information System (INIS)

    Lambert, G.

    1981-05-01

    For several years now, fuel elements from graphite gas reactors have been stored in pools at the Cadarache Center after having been subjected (in general) to laboratory examinations. The CEA has adopted the following re-transfer procedure for these fuel elements while awaiting reprocessing: the fuel elements are extracted from their existing cartridges and transferred into new welded stainless steel containers capable of assuring long term storage. The storage, however, envisaged is temporary and is realized in the Pegase pool, specially adapted for this purpose. This re-transfer operation is envisaged for some 2.300 containers. All the appropriate safety measures will be taken. The various different fuel materials handled are often highly irradiated. The presence of water in certain containers due to loss of leaktightness has led to a series of chemical reactions (corrosion of uranium by water, reactions with magnesium, formation of hydrides). As a result, existing envelopes can contain UO 2 , UH 3 and hydrogen; operations must therefore being carried out in an inert atmosphere (preferably argon). The re-transfer process can not therefore be carried out in a conventional cell. It is therefore envisaged to carry out this work in a leaktight cell in an inert atmosphere. A laboratory cell could be modified to perform these functions. This cell would be reconverted to its original state when operations terminate (in about 3 years time) [fr

  9. NGC 404: A REJUVENATED LENTICULAR GALAXY ON A MERGER-INDUCED, BLUEWARD EXCURSION INTO THE GREEN VALLEY

    International Nuclear Information System (INIS)

    Thilker, David A.; Bianchi, Luciana; Schiminovich, David; Gil de Paz, Armando; Seibert, Mark; Madore, Barry F.; Wyder, Ted; Barlow, Tom; Conrow, Tim; Forster, Karl; Friedman, Peter; Martin, Chris; Morrissey, Patrick; Small, Todd; Rich, R. Michael; Yi, Sukyoung; Neff, Susan

    2010-01-01

    We have discovered recent star formation in the outermost portion ((1-4) x R 25 ) of the nearby lenticular (S0) galaxy NGC 404 using Galaxy Evolution Explorer UV imaging. FUV-bright sources are strongly concentrated within the galaxy's H I ring (formed by a merger event according to del RIo et al.), even though the average gas density is dynamically subcritical. Archival Hubble Space Telescope imaging reveals resolved upper main-sequence stars and conclusively demonstrates that the UV light originates from recent star formation activity. We present FUV, NUV radial surface brightness profiles, and integrated magnitudes for NGC 404. Within the ring, the average star formation rate (SFR) surface density (Σ SFR ) is ∼2.2 x 10 -5 M sun yr -1 kpc -2 . Of the total FUV flux, 70% comes from the H I ring which is forming stars at a rate of 2.5 x 10 -3 M sun yr -1 . The gas consumption timescale, assuming a constant SFR and no gas recycling, is several times the age of the universe. In the context of the UV-optical galaxy color-magnitude diagram, the presence of the star-forming H I ring places NGC 404 in the green valley separating the red and blue sequences. The rejuvenated lenticular galaxy has experienced a merger-induced, disk-building excursion away from the red sequence toward bluer colors, where it may evolve quiescently or (if appropriately triggered) experience a burst capable of placing it on the blue/star-forming sequence for up to ∼1 Gyr. The green valley galaxy population is heterogeneous, with most systems transitioning from blue to red but others evolving in the opposite sense due to acquisition of fresh gas through various channels.

  10. Osteocyte Lacunae are Lenticular/Ellipsoid Spaces or Spiral/Helical Tubules

    Directory of Open Access Journals (Sweden)

    Bijit Kanti Guha

    2017-10-01

    Full Text Available Introduction: According to the current concept of bone structure, the osteocyte lacunae are lenticular or ellipsoid spaces occupied by osteocytes. These osteocytes are thought to communicate with each other through a tubular system made up of Canaliculi. The rest of the structures i.e., Haversian canal, and Volkmann’s canal are also tubular in shape. Considering this existing concept of bone microstructure described by various authors, it is highly unlikely that the lacunae alone would be lenticular/ellipsoid structure. In the present study author wanted to know that amongst the all tubular spaces, what is the reason that only the osteocyte lacunae are lenticular or ellipsoid structure? Also to investigate whether these lenticular spaces are really lenticular/ellipsoid or they are cut sections of tubes, which are lying helically or spirally. It is well known from various previous studies that Haversian canal, Volkmann’s canal and Canaliculi are tubular shaped structures and how it is possible that lenticular/ellipsoid structure can present amongst them. So we thought that, it may be possible that these lenticular spaces are not actually lenticular but this lenticular shape is due to the cut sections of any type of tubule in various possible planes (i.e., transverse, longitudinal and various degrees of oblique plane. Aim: The present study was carried out to reinvestigate the shape of the osteocyte lacunae amongst the tubular system (i.e., Haversian canal, Volkmann’s canal and Canaliculi of compact bone. Materials and Methods: The study is carried out by preparing thin sections of adult bones (ground glass preparation and visualizing them under binocular light microscope and scanelectron microscope after following proper procedure. Results: We observed that the lacunae are actually spirally/helically placed tubules with several branching. These branching are considered as canaliculi. These branching are of various diameters and they

  11. Effect of weave tightness and structure on the in-plane and through-plane air permeability of woven carbon fibers for gas diffusion layers

    Energy Technology Data Exchange (ETDEWEB)

    Caston, Terry B.; Murphy, Andrew R.; Harris, Tequila A.L. [Department of Mechanical Engineering, Georgia Institute of Technology, Atlanta, GA (United States)

    2011-01-15

    In this study, woven gas diffusion layers (GDLs) with varying weave type and tightness are investigated. Plain and twill weave patterns were manufactured in-house. The in-plane and through-plane air permeability of the woven samples were tested, and mercury intrusion porosimetry (MIP) tests were performed to study the pore structure. It was found that the twill weave has a higher permeability than the plain weave, which is consistent with literature. Like non-woven carbon papers, woven GDLs have higher in-plane permeability than through-plane permeability; however it has been shown that it is possible to manufacture a GDL with higher through-plane permeability than in-plane permeability. It was also concluded that the percentage of macropores in the weave is the driving factor in determining the through-plane air permeability. This work lays the groundwork for future studies to attempt to characterize the relationship between the weave structure and the air permeability in woven GDLs. (author)

  12. Fabrication of micro-lenticular patterns using WEDM-grooving and electrolytic polishing

    Science.gov (United States)

    Park, Jong Wuk; Song, Ki Young; Chung, Do Kwan; Chu, Chong Nam

    2013-12-01

    Lenticular pattern panels have been used for displaying 3D effects and their precise fabrication methods have attracted great attention. In this study, we present a novel fabrication method for lenticular patterns on a stainless steel mold (AISI 304). The fabrication process was composed of two steps. First, the lenticular shape groove was machined by wire-electrical discharge machining (EDM) (WEDM-grooving). In this step, EDM was adopted because it is useful for machining hard-to-cut material such as WC-Co, stainless steel and titanium, and a newly developed wire grooving system ensures highly accurate machining. Second, electrolytic polishing was carried out afterward to improve the surface quality since the machined surface resulting from the WEDM-grooving was rough. The entire fabrication processes required a single machine and deionized water only; thus, the step change time was minimized and the method was eco-friendly. Parametric tests for the WEDM-grooving conditions as well as for the proper electrolytic polishing conditions (voltage, offset and feedrate) were executed to fabricate the grooves with fine surface. Excessive electrolytic polishing conditions caused pitting and damage from the additional sparks on the surface of the mold. On the other hand, inadequate machining conditions resulted in an incomplete electrolytic polishing process. Using this multi-step process, a lenticular pattern mold with high surface quality was machined. The lenticular pattern PDMS lens was successfully produced using the stainless steel mold.

  13. Analysis of trends in fuel rod depressurization and determination of 'gas leak' and 'pellet-water interaction' type failures using radiation monitoring techniques of fuel rod leak tightness

    International Nuclear Information System (INIS)

    Panov, E.A.; Shestakov, Yu.M.; Miglo, V.N.

    1993-01-01

    Analysis of fuel rod failures in the Light Water Reactor operation is presented. Analysis includes the mechanism of formation and development of fuel rod cladding failure until through-wall defects appear (welding defects; inner hydriding defects; pellet-cladding interaction; crud deposit - intensified corrosion) as well as factors that determine defects propagation after fuel rod depressurization (metal condition in the vicinity of defect determined by the mechanism of formation and propagation defect; operational transients; degree of core cooldown after depressurization during preventive maintenance). Possibilities of in-service monitoring of fuel rod through-wall crack propagation using normal tools of cladding back-tightness monitoring are addressed and used in the course of analysis. Characteristics and values are presented for radiation parameters for fuel assemblies during propagation of defects with different degrees of rod depressurization, including ''gas leak'', cladding crack and ''open pellet-water interaction'' with potential particulate fission product release from the damaged rods as well as after formation of recurring defects. Based on experimental data on specific activity of different iodine isotopes in the primary coolant, a mathematical model to analyse defect propagation trends has been developed. The model describes the rate of radionuclide release from depressurized rods and the rate of nuclear fuel fission processes in the vicinity of defects. The model and results of analysis are illustrated by experimental and statistical data on depressurization of WWER (PWR) and RBMK (BWR) reactor fuel rods. Possibility to solve the problem of predicting defect propagation is considered. (author). 5 refs, 9 figs, 3 tabs

  14. Geostatistical Three-Dimensional Modeling of a Tight Gas Reservoir: A Case Study of Block S6 of the Sulige Gas Field, Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Jinliang Zhang

    2017-09-01

    Full Text Available In this study, three-dimensional (3-D geostatistical models were constructed to quantify distributions of sandstone and mudstone. We propose a new method that employs weight coefficients to balance the sandstone and mudstone data from irregular well patterns during stochastic modeling. This new method begins with classifying well groups according to well distribution patterns; areas with similar well distribution patterns are classified within the same zone. Then, the distributions of sandstone and mudstone for each zone are simulated separately using the sequential indicator simulation (SIS method, and the relevant variogram parameters for each zone are computed. In this paper, we used block S6 of the Sulige Gas Field in Ordos Basin in China as a case study. We evaluated the quality of each set of parameters through the vacuation checking method; certain wells were removed to generate equiprobable realizations using different seed numbers. Subsequently, the variogram parameters for the entire S6 area were obtained by assigning different weight coefficients to the parameters of each zone. Finally, a quality assessment of the sandstone and mudstone models of the S6 area was conducted using the horizontal wells, which were not involved in the stochastic modeling process. The results show that these variogram parameters, which were calculated using weight coefficients, are reliable.

  15. Moiré-reduction method for slanted-lenticular-based quasi-three-dimensional displays

    Science.gov (United States)

    Zhuang, Zhenfeng; Surman, Phil; Zhang, Lei; Rawat, Rahul; Wang, Shizheng; Zheng, Yuanjin; Sun, Xiao Wei

    2016-12-01

    In this paper we present a method for determining the preferred slanted angle for a lenticular film that minimizes moiré patterns in quasi-three-dimensional (Q3D) displays. We evaluate the preferred slanted angles of the lenticular film for the stripe-type sub-pixel structure liquid crystal display (LCD) panel. Additionally, the sub-pixels mapping algorithm of the specific angle is proposed to assign the images to either the right or left eye channel. A Q3D display prototype is built. Compared with the conventional SLF, this newly implemented Q3D display can not only eliminate moiré patterns but also provide 3D images in both portrait and landscape orientations. It is demonstrated that the developed slanted lenticular film (SLF) provides satisfactory 3D images by employing a compact structure, minimum moiré patterns and stabilized 3D contrast.

  16. The SAURON project - VI. Line strength maps of 48 elliptical and lenticular galaxies

    NARCIS (Netherlands)

    Kuntschner, Harald; Emsellem, Eric; Bacon, R.; Bureau, M.; Cappellari, Michele; Davies, Roger L.; de Zeeuw, P. T.; Falcon-Barroso, Jesus; Krajnovic, Davor; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc

    2006-01-01

    We present absorption line strength maps of 48 representative elliptical and lenticular galaxies obtained as part of a survey of nearby galaxies using our custom-built integral-field spectrograph, SAURON, operating on the William Herschel Telescope. Using high-quality spectra, spatially binned to a

  17. Reduction of the thickness of lenticular stereoscopic display using full-color LED panel

    Science.gov (United States)

    Yamamoto, Hirotsugu; Muguruma, Syuji; Hayasaki, Yoshio; Nagai, Yoshifumi; Shimizu, Yoshinori; Nishida, Nobuo

    2002-05-01

    The goals of our research are to realize stereoscopic large displays for the general public in the open air. These goals impose certain design constraints. It is preferable to view stereoscopic images without any special glasses. Multiple viewing areas are necessary to crowds of viewers. The thickness of the stereoscopic large display is a problem for installations. We have developed a stereoscopic full color LED display using parallax barrier and demonstrated multiple viewing areas. However, the thickness of that stereoscopic display, which is consisted of 8-mm pitch LED panel, becomes over 2 min the case that the viewing distance is designed for 20 m. In order to reduce the thickness of stereoscopic LED display, we propose use of dual lenticular sheets. The first lenticular sheet performs multiple imaging, which allows multiple viewing areas without diffusion screen. The second lenticular sheets separates the raster images into the right and left eye positions. The thickness, which is defined as the distance between the LED panel and the second lenticular sheet, can be reduced below 50cm for the viewing distance of 20 m. Optimal parameters are discussed to reduce the thickness.

  18. Fault features and enrichment laws of narrow-channel distal tight sandstone gas reservoirs: A case study of the Jurassic Shaximiao Fm gas reservoir in the Zhongjiang Gas Field, Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Zhongping Li

    2016-11-01

    Full Text Available The Jurassic Shaximiao Fm gas reservoir in the Zhongjiang Gas Field, Sichuan Basin, is the main base of Sinopec Southwest Oil & Gas Company for gas reserves and production increase during the 12th Five-Year Plan. However, its natural gas exploration and development process was restricted severely, since the exploration wells cannot be deployed effectively in this area based on the previous gas accumulation and enrichment pattern of “hydrocarbon source fault + channel sand body + local structure”. In this paper, the regional fault features and the gas accumulation and enrichment laws were discussed by analyzing the factors like fault evolution, fault elements, fault-sand body configuration (the configuration relationship between hydrocarbon source faults and channel sand bodies, trap types, and reservoir anatomy. It is concluded that the accumulation and enrichment of the Shaximiao Fm gas reservoir in this area is controlled by three factors, i.e., hydrocarbon source, sedimentary facies and structural position. It follows the accumulation laws of source controlling region, facies controlling zone and position controlling reservoir, which means deep source and shallow accumulation, fault-sand body conductivity, multiphase channel, differential accumulation, adjusted enrichment and gas enrichment at sweet spots. A good configuration relationship between hydrocarbon source faults and channel sand bodies is the basic condition for the formation of gas reservoirs. Natural gas accumulated preferentially in the structures or positions with good fault-sand body configuration. Gas reservoirs can also be formed in the monoclinal structures which were formed after the late structural adjustment. In the zones supported by multiple faults or near the crush zones, no gas accumulation occurs, but water is dominantly produced. The gas-bearing potential is low in the area with undeveloped faults or being 30 km away from the hydrocarbon source faults. So

  19. Contraption and Prediction of Exhalation Tight Brownstone in Exhalation Cistern

    OpenAIRE

    XhingZhiwang, -; Xuchao, -

    2012-01-01

    The reservoir connate water saturation is high and gas wells generally produce water which seriously affects the productivity of gas wells in Xujiahe tight sandstone gas reservoirs in Sichuan Basin. Take the sixth formation for example, there are 39 wells producing water unequally in the 42 commissioning wells, and the excessive water production leads to the production of the gas well declining rapidly. Studying of the mechanism of water production in tight sandstone gas reservoirs and predic...

  20. Dynamic Resolution in GPU-Accelerated Volume Rendering to Autostereoscopic Multiview Lenticular Displays

    OpenAIRE

    Daniel Ruijters

    2008-01-01

    The generation of multiview stereoscopic images of large volume rendered data demands an enormous amount of calculations. We propose a method for hardware accelerated volume rendering of medical data sets to multiview lenticular displays, offering interactive manipulation throughout. The method is based on buffering GPU-accelerated direct volume rendered visualizations of the individual views from their respective focal spot positions, and composing the output signal for the multiview lenticu...

  1. Dynamic Resolution in GPU-Accelerated Volume Rendering to Autostereoscopic Multiview Lenticular Displays

    Directory of Open Access Journals (Sweden)

    Daniel Ruijters

    2008-09-01

    Full Text Available The generation of multiview stereoscopic images of large volume rendered data demands an enormous amount of calculations. We propose a method for hardware accelerated volume rendering of medical data sets to multiview lenticular displays, offering interactive manipulation throughout. The method is based on buffering GPU-accelerated direct volume rendered visualizations of the individual views from their respective focal spot positions, and composing the output signal for the multiview lenticular screen in a second pass. This compositing phase is facilitated by the fact that the view assignment per subpixel is static, and therefore can be precomputed. We decoupled the resolution of the individual views from the resolution of the composited signal, and adjust the resolution on-the-fly, depending on the available processing resources, in order to maintain interactive refresh rates. The optimal resolution for the volume rendered views is determined by means of an analysis of the lattice of the output signal for the lenticular screen in the Fourier domain.

  2. Sonographic alteration of lenticular nucleus in focal task-specific dystonia of musicians.

    Science.gov (United States)

    Walter, Uwe; Buttkus, Franziska; Benecke, Reiner; Grossmann, Annette; Dressler, Dirk; Altenmüller, Eckart

    2012-01-01

    In distinct movement disorders, transcranial sonography detects alterations of deep brain structures with higher sensitivity than other neuroimaging methods. Lenticular nucleus hyperechogenicity on transcranial sonography, thought to be caused by increased local copper content, has been reported as a characteristic finding in primary spontaneous dystonia. Here, we wanted to find out whether deep brain structures are altered in task-specific dystonia. The frequency of sonographic brainstem and basal ganglia changes was studied in an investigator-blinded setting in 15 musicians with focal task-specific hand dystonia, 15 musicians without dystonia, and 15 age- and sex-matched nonmusicians without dystonia. Lenticular nucleus hyperechogenicity was found in 12 musicians with task-specific dystonia, but only in 3 nondystonic musicians (Fisher's exact test, p = 0.001) and 2 nonmusicians (p musicians correlated with age, but not with duration of music practice or duration of dystonia. In 2 of 3 affected musicians with normal echogenic lenticular nucleus, substantia nigra hyperechogenicity was found. Our findings support the idea of a pathogenetic link between primary spontaneous and task-specific dystonia. Sonographic basal ganglia alteration might indicate a risk factor that in combination with extensive fine motor training promotes the manifestation of task-specific dystonia. Copyright © 2011 S. Karger AG, Basel.

  3. Meridional lenticular astigmatism associated with bilateral concurrent uveal metastases in renal cell carcinoma

    Directory of Open Access Journals (Sweden)

    Priluck JC

    2012-11-01

    Full Text Available Joshua C Priluck, Sandeep Grover, KV ChalamDepartment of Ophthalmology, University of Florida College of Medicine, Jacksonville, FL, USAPurpose: To demonstrate a case illustrating meridional lenticular astigmatism as a result of renal cell carcinoma uveal metastases.Methods: Case report with images.Results: Clinical findings and diagnostic testing of a patient with acquired meridional lenticular astigmatism are described. The refraction revealed best-corrected visual acuity of 20/20–1 OD (−2.50 + 0.25 × 090 and 20/50 OS (−8.25 + 3.25 × 075. Bilateral concurrent renal cell carcinoma metastases to the choroid and ciliary body are demonstrated by utilizing ultrasonography, ultrawidefield fluorescein angiography, and unique spectral-domain optical coherence tomography.Conclusions: Metastatic disease should be included in the differential of acquired astigmatism. Spectral-domain optical coherence tomography, ultrawidefield fluorescein angiography, and ultrasonography have roles in delineating choroidal metastases.Keywords: astigmatism, metastasis, optical coherence tomography, renal cell carcinoma

  4. Dynamical models of two lenticular galaxies: NGC 1023 and NGC 4526

    Directory of Open Access Journals (Sweden)

    Samurović S.

    2017-01-01

    Full Text Available We study kinematics and dynamics of two lenticular galaxies that possess globular clusters (GCs which extend beyond approximately seven effective radii. We analyze two nearby lenticular galaxies, NGC 1023 and NGC 4526, based on their GCs. We extract the kinematics of these galaxies and use it for dynamical modeling based on the Jeans equation. The Jeans equation was solved in both the Newtonian mass-follows-light approach assuming constant mass-to-light ratio and assuming a dark halo in the Navarro-Frenk-White form. We find that while the first galaxy, NGC 1023, does not need a significant amount of dark matter, in the other galaxy, NGC 4526, the dark component fully dominates stellar matter in the total dynamical mass. In this paper we also used three different MOND approaches and found that while for both galaxies MOND models can provide successful fits of the observed velocity dispersion, in the case of NGC 4526 we have a hint of an additional dark component even in the MOND framework. [Project of the Serbian Ministry of Education, Science and Technological Development, Grant no. 176021: Visible and Invisible Matter in Nearby Galaxies: Theory and Observations

  5. Lenticular Subluxation in a Patient with Homocystinuria Undetected by Neonatal Screening

    Directory of Open Access Journals (Sweden)

    Kang-Hsiang Cheng

    2007-12-01

    Full Text Available A case of homocystinuria with lenticular subluxation was misdiagnosed as Marfan syndrome since the patient had no apparent mental impairment and had had a negative neonatal screen for homocystinuria. The delayed diagnosis of homocystinuria was due to a negative prior neonatal screen which was checked when he was a breastfed healthy newborn. In the absence of an autosomal dominant family history, and because of prior poor school performance, amino acid analysis and mutational analysis of the cystathionine b-synthase gene were performed, which revealed the presence of homocystinuria. Low methionine diet with vitamin B6, folic acid, betaine, dipyridamole and aspirin was prescribed for emergency ophthalmologic surgery to prevent thromboembolic events. Fortunately, the operation was completed uneventfully. The patient has been followed-up for 4 years without any significant complaints under diet and medical control. Since homocystinuria is easily missed in neonatal screening programs, it should be suspected in patients who present with lenticular subluxation, even after a negative neonatal screen.

  6. Quantifying opening-mode fracture spatial organization in horizontal wellbore image logs, core and outcrop: Application to Upper Cretaceous Frontier Formation tight gas sandstones, USA

    Science.gov (United States)

    Li, J. Z.; Laubach, S. E.; Gale, J. F. W.; Marrett, R. A.

    2018-03-01

    The Upper Cretaceous Frontier Formation is a naturally fractured gas-producing sandstone in Wyoming. Regionally, random and statistically more clustered than random patterns exist in the same upper to lower shoreface depositional facies. East-west- and north-south-striking regional fractures sampled using image logs and cores from three horizontal wells exhibit clustered patterns, whereas data collected from east-west-striking fractures in outcrop have patterns that are indistinguishable from random. Image log data analyzed with the correlation count method shows clusters ∼35 m wide and spaced ∼50 to 90 m apart as well as clusters up to 12 m wide with periodic inter-cluster spacings. A hierarchy of cluster sizes exists; organization within clusters is likely fractal. These rocks have markedly different structural and burial histories, so regional differences in degree of clustering are unsurprising. Clustered patterns correspond to fractures having core quartz deposition contemporaneous with fracture opening, circumstances that some models suggest might affect spacing patterns by interfering with fracture growth. Our results show that quantifying and identifying patterns as statistically more or less clustered than random delineates differences in fracture patterns that are not otherwise apparent but that may influence gas and water production, and therefore may be economically important.

  7. Continuous Shearlet Tight Frames

    KAUST Repository

    Grohs, Philipp

    2010-10-22

    Based on the shearlet transform we present a general construction of continuous tight frames for L2(ℝ2) from any sufficiently smooth function with anisotropic moments. This includes for example compactly supported systems, piecewise polynomial systems, or both. From our earlier results in Grohs (Technical report, KAUST, 2009) it follows that these systems enjoy the same desirable approximation properties for directional data as the previous bandlimited and very specific constructions due to Kutyniok and Labate (Trans. Am. Math. Soc. 361:2719-2754, 2009). We also show that the representation formulas we derive are in a sense optimal for the shearlet transform. © 2010 Springer Science+Business Media, LLC.

  8. A density functional tight binding/force field approach to the interaction of molecules with rare gas clusters: application to (C6H6)(+/0)Ar(n) clusters.

    Science.gov (United States)

    Iftner, Christophe; Simon, Aude; Korchagina, Kseniia; Rapacioli, Mathias; Spiegelman, Fernand

    2014-01-21

    We propose in the present paper a SCC-DFTB/FF (Self-Consistent-Charge Density Functional based Tight Binding/Force-Field) scheme adapted to the investigation of molecules trapped in rare gas environments. With respect to usual FF descriptions, the model involves the interaction of quantum electrons in a molecule with rare gas atoms in an anisotropic scheme. It includes polarization and dispersion contributions and can be used for both neutral and charged species. Parameters for this model are determined for hydrocarbon-argon complexes and the model is validated for small hydrocarbons. With the future aim of studying polycyclic aromatic hydrocarbons in Ar matrices, extensive benchmark calculations are performed on (C6H6)(+/0)Arn clusters against DFT and CCSD(T) calculations for the smaller sizes, and more generally against other experimental and theoretical data. Results on the structures and energetics (isomer ordering and energy separation, cohesion energy per Ar atom) are presented in detail for n = 1-8, 13, 20, 27, and 30, for both neutrals and cations. We confirm that the clustering of Ar atoms leads to a monotonous decrease of the ionization potential of benzene for n ⩽ 20, in line with previous experimental and FF data.

  9. Metalclad substation subdivided into tight compartments

    Energy Technology Data Exchange (ETDEWEB)

    Diaferia, A.; Messie, M.

    1990-02-06

    This invention relates to a high voltage metalclad substation, having a metal enclosure, filled with a high dielectric strength gas, and subdivided into different compartments by tight insulating partitions. The object of this invention is to achieve a simplified substation of reduced dimensions preserving the possibilities of performing operations on part of the substation, while the other part remains live. According to the invention, a metalclad substation is provided, having a busbar isolating switch including an operating mechanism housed in the busbar compartment. The movable contacts of the isolating switch are housed in a compartment separated by a tight insulating partition from the busbar compartment. Tight partitioning of the compartments enables operations to be carried out in the different compartments while maintaining at least one of the busbars switched on to supply the unaffected part of the installation. The invention can be applied to a single-phase or a three-phase enclosure substation. 4 figs.

  10. Opportunities and risks of hydraulic fraction treatment of tight gas-carrying rocks in redbeds; Chancen und Risiken hydraulischer Fracbehandlungen von dichten Erdgasspeichergesteinen im Rotliegenden

    Energy Technology Data Exchange (ETDEWEB)

    Buhrow, C. [BEB Erdgas und Erdoel GmbH, Hannover (Germany)

    1998-12-31

    In the last 20 years more and more hydraulic fraction treatments have been carried out in natural gas-carrying strata of the redbed. By pumping high-viscosity liquids into the rocks one attempts to control the fraction. Towards the end of the treatment the fraction is filled with a proppant in order to create a flow path with high permeability to the borehole after the pressure of the liquid drops. The trend moves from large-volume single fractures - more than 2000 cubic m of liquid as several tons of proppant were used in some cases -. to smaller fraction treatments consisting of a minimum of two fractures: the first one, which usually employs small amounts of liquid and proppant, serves to gain information on the deposit and its suitability for fraction treatment. The one or several fractures that follow serve to increase production or enlarge the drainage area. Ground pressure measurements can provide important information about the development of the fracture before, during and after fracturing. (orig.) [Deutsch] Seit ca. 20 Jahren werden vermehrt hydraulische Fracbehandlungen in den Erdgasspeichergesteinen des Rotliegenden durchgefuehrt. Durch Verpumpen von Fluessigkeiten hoher Viskositaet soll kontrolliert ein Riss `Frac` genannt, im Gebirge geschaffen werden. Dieser wird gegen Ende der Behandlung mit Stuetzmittel angefuellt, um nach Abfall des Fluessigkeitsdrucks einen bleibenden Fliessweg hoher Permeabilitaet zum Bohrloch zu schaffen. Dabei hat es eine Entwicklung von grossvolumigen Einzelfracs - in Einzelfaellen wurden mehr als 2.000 m{sup 3} Fluessigkeit und mehrere hundert Tonnen Stuetzmittel verpumpt - hin zu kleineren Fracbehandlungen aus zumindest zwei Fracs gegeben: Ziel des ersten, zumeist nur geringe Fluessigkeitsvolumina und Stuetzmittelmengen enthaltenen Fracs ist es, Informationen ueber die Lagerstaette und deren Fracbehandelbarkeit zu erlangen. Der oder die nachfolgenden Fracs dienen dann dem eigentlichen Ziel, der Produktionssteigerung und der

  11. Axial growth and changes in lenticular and corneal power during emmetropization in infants.

    Science.gov (United States)

    Mutti, Donald O; Mitchell, G Lynn; Jones, Lisa A; Friedman, Nina E; Frane, Sara L; Lin, Wendy K; Moeschberger, Melvin L; Zadnik, Karla

    2005-09-01

    To evaluate the contribution made by the ocular components to the emmetropization of spherical equivalent refractive error in human infants between 3 and 9 months of age. Keratophakometry in two meridians was performed on 222 normal-birthweight infant subjects at 3 and 9 months of age. The spherical equivalent refractive error was measured by cycloplegic retinoscopy (cyclopentolate 1%). Anterior chamber depth, lens thickness, and vitreous chamber depth were measured by A-scan ultrasonography over the closed eyelid. Both the mean and SD for spherical equivalent refractive error decreased between 3 and 9 months of age (+2.16 +/- 1.30 D at 3 months; +1.36 +/- 1.06 D at 9 months; P < 0.0001, for the change in both mean and SD). Average ocular component change was characterized by increases in axial length, thinning, and flattening of the crystalline lens, increases in lens equivalent refractive index, and decreases in lens and corneal power. Initial refractive error was associated in a nonlinear manner with the change in refractive error (R(2) = 0.41; P < 0.0001) and with axial growth (R(2) = 0.082; P = 0.0005). Reduction in hyperopia correlated significantly with increases in axial length (R(2) = 0.16; P < 0.0001), but not with changes in corneal and lenticular power. Decreases in lenticular and corneal power were associated with axial elongation (R(2) = 0.40, R(2) = 0.12, respectively; both P < 0.0001). Modulation in the amount of axial growth in relation to initial refractive error appeared to be the most influential factor in emmetropization of spherical equivalent refractive error. The associations between initial refractive error, subsequent axial growth, and change in refractive error were consistent with a visual basis for emmetropization. The cornea and crystalline lens lost substantial amounts of dioptric power in this phase of growth, but neither appeared to play a significant role in emmetropization.

  12. Septic implantation syndrome in dogs and cats: a distinct pattern of endophthalmitis with lenticular abscess.

    Science.gov (United States)

    Bell, Cynthia M; Pot, Simon A; Dubielzig, Richard R

    2013-05-01

    To summarize the clinical and pathologic findings in a group of dogs and cats with progressive clinical ocular disease, which were diagnosed with suppurative endophthalmitis and lens capsule rupture. Twenty cats and forty-six dogs that underwent unilateral enucleation or evisceration for intractable uveitis and/or glaucoma. Biopsy submission requests and microscopic case material were evaluated for clinical and histological features, including history of ocular trauma, duration of ocular disease, pattern of inflammation, and the presence of intralenticular microorganisms. The median duration for cats and dogs was 6 and 5 weeks, respectively. A history of trauma was reported for four (20%) cats and 18 (39%) dogs. All confirmed cases of trauma-three in cats and 14 in dogs-were caused by a cat scratch. Microscopically, all cases had suppurative endophthalmitis centered on the lens, lens capsule rupture, cataract, and lenticular abscess. Infectious organisms were identified by Gram stain within the lens of 14 (70%) cats and 30 (65%) dogs. Gram-positive cocci were seen most commonly. Male cats were overrepresented as compared to females. There were no apparent gender, age or breed predilections in dogs. A unique pattern of slowly progressive or delayed-onset endophthalmitis with lens capsule rupture, lenticular abscess, and frequently intralenticular microorganisms is associated with traumatic penetration of the globe and lens capsule. The term Septic Implantation Syndrome (SIS) is favored in lieu of 'phacoclastic uveitis' to avoid confusion with phacolytic uveitis and to clearly implicate the role of intralenticular microorganisms in the pathogenesis. © 2012 American College of Veterinary Ophthalmologists.

  13. Tight closure and vanishing theorems

    International Nuclear Information System (INIS)

    Smith, K.E.

    2001-01-01

    Tight closure has become a thriving branch of commutative algebra since it was first introduced by Mel Hochster and Craig Huneke in 1986. Over the past few years, it has become increasingly clear that tight closure has deep connections with complex algebraic geometry as well, especially with those areas of algebraic geometry where vanishing theorems play a starring role. The purpose of these lectures is to introduce tight closure and to explain some of these connections with algebraic geometry. Tight closure is basically a technique for harnessing the power of the Frobenius map. The use of the Frobenius map to prove theorems about complex algebraic varieties is a familiar technique in algebraic geometry, so it should perhaps come as no surprise that tight closure is applicable to algebraic geometry. On the other hand, it seems that so far we are only seeing the tip of a large and very beautiful iceberg in terms of tight closure's interpretation and applications to algebraic geometry. Interestingly, although tight closure is a 'characteristic p' tool, many of the problems where tight closure has proved useful have also yielded to analytic (L2) techniques. Despite some striking parallels, there had been no specific result directly linking tight closure and L∼ techniques. Recently, however, the equivalence of an ideal central to the theory of tight closure was shown to be equivalent to a certain 'multiplier ideal' first defined using L2 methods. Presumably, deeper connections will continue to emerge. There are two main types of problems for which tight closure has been helpful: in identifying nice structure and in establishing uniform behavior. The original algebraic applications of tight closure include, for example, a quick proof of the Hochster-Roberts theorem on the Cohen-Macaulayness of rings of invariants, and also a refined version of the Brianqon-Skoda theorem on the uniform behaviour of integral closures of powers of ideals. More recent, geometric

  14. Leak-tight compressor

    International Nuclear Information System (INIS)

    Bogomolova, L.K.; Vasilenko, A.T.

    1974-01-01

    The publication describes the construction and operating principle of the sealed uniflow compressor. This compressor insures against substantial contamination of the medium handled. Use of the slot-type sealing of the piston and rejection of the sliding bearings result in insuring high purity of the medium handled. The compressor performance is as follows: maximum air throughput - 262.6 1/h at 24 deg C and absolute outlet pressure being 1.14 kgf/cm 2 , minimum air throughput - 82.6 1/h at 24 deg C and absolute outlet pressure being 1.4 kgf/cm 2 ; inlet pressure equals 1 kgf/cm 2 . The compressor is provided with a solenoid-operated drive. The prototype has been in service for 6 months, with accumulated service time amounting to 500 h. The compressor has given a good account of itself within this period. The compressor is to be used in the gas purification circuit when this gas is used as a working medium in the spark or streamer chambers

  15. An over-massive black hole in the compact lenticular galaxy NGC 1277.

    Science.gov (United States)

    van den Bosch, Remco C E; Gebhardt, Karl; Gültekin, Kayhan; van de Ven, Glenn; van der Wel, Arjen; Walsh, Jonelle L

    2012-11-29

    Most massive galaxies have supermassive black holes at their centres, and the masses of the black holes are believed to correlate with properties of the host-galaxy bulge component. Several explanations have been proposed for the existence of these locally established empirical relationships, including the non-causal, statistical process of galaxy-galaxy merging, direct feedback between the black hole and its host galaxy, and galaxy-galaxy merging and the subsequent violent relaxation and dissipation. The empirical scaling relations are therefore important for distinguishing between various theoretical models of galaxy evolution, and they furthermore form the basis for all black-hole mass measurements at large distances. Observations have shown that the mass of the black hole is typically 0.1 per cent of the mass of the stellar bulge of the galaxy. Until now, the galaxy with the largest known fraction of its mass in its central black hole (11 per cent) was the small galaxy NGC 4486B. Here we report observations of the stellar kinematics of NGC 1277, which is a compact, lenticular galaxy with a mass of 1.2 × 10(11) solar masses. From the data, we determine that the mass of the central black hole is 1.7 × 10(10) solar masses, or 59 per cent of its bulge mass. We also show observations of five other compact galaxies that have properties similar to NGC 1277 and therefore may also contain over-massive black holes. It is not yet known if these galaxies represent a tail of a distribution, or if disk-dominated galaxies fail to follow the usual black-hole mass scaling relations.

  16. Proposed Ames M2-F1, M1-L half-cone, and Langley lenticular bodies.

    Science.gov (United States)

    1962-01-01

    Dale Reed, who inaugurated the lifting-body flight research at NASA's Flight Research Center (later, Dryden Flight Research Center, Edwards, CA), originally proposed that three wooden outer shells be built. These would then be attached to the single internal steel structure. The three shapes were (viewer's left to right) the M2-F1, the M1-L, and a lenticular shape. Milt Thompson, who supported Reed's advocacy for a lifting-body research project, recommended that only the M2-F1 shell be built, believing that the M1-L shape was 'too radical,' while the lenticular one was 'too exotic.' Although the lenticular shape was often likened to that of a flying saucer, Reed's wife Donna called it the 'powder puff.' The wingless, lifting body aircraft design was initially conceived as a means of landing an aircraft horizontally after atmospheric reentry. The absence of wings would make the extreme heat of re-entry less damaging to the vehicle. In 1962, Dryden management approved a program to build a lightweight, unpowered lifting body as a prototype to flight test the wingless concept. It would look like a 'flying bathtub,' and was designated the M2-F1, the 'M' referring to 'manned' and 'F' referring to 'flight' version. It featured a plywood shell placed over a tubular steel frame crafted at Dryden. Construction was completed in 1963. The first flight tests of the M2-F1 were over Rogers Dry Lake at the end of a tow rope attached to a hopped-up Pontiac convertible driven at speeds up to about 120 mph. This vehicle needed to be able to tow the M2-F1 on the Rogers Dry Lakebed adjacent to NASA's Flight Research Center (FRC) at a minimum speed of 100 miles per hour. To do that, it had to handle the 400-pound pull of the M2-F1. Walter 'Whitey' Whiteside, who was a retired Air Force maintenance officer working in the FRC's Flight Operations Division, was a dirt-bike rider and hot-rodder. Together with Boyden 'Bud' Bearce in the Procurement and Supply Branch of the FRC, Whitey

  17. Tightness of voter model interfaces

    Czech Academy of Sciences Publication Activity Database

    Sturm, A.; Swart, Jan M.

    2008-01-01

    Roč. 13, - (2008), s. 165-174 ISSN 1083-589X R&D Projects: GA ČR GA201/06/1323; GA ČR GA201/07/0237 Institutional research plan: CEZ:AV0Z10750506 Keywords : long range voter model * swapping voter model * interface tightness * exclusion process Subject RIV: BD - Theory of Information Impact factor: 0.392, year: 2008 http://www.emis.de/journals/EJP-ECP/_ejpecp/index.html

  18. PCBS AND TIGHT JUNCTION EXPRESSION

    OpenAIRE

    Eum, Sung Yong; András, Ibolya E.; Couraud, Pierre-Olivier; Hennig, Bernhard; Toborek, Michal

    2008-01-01

    Polychlorinated biphenyl (PCB) congeners exhibit a broad range of adverse biological effects including neurotoxicity. The mechanisms by which PCBs cause neurotoxic effects are still not completely understood. The blood-brain barrier (BBB) is a physical and metabolic barrier separating brain microenvironment from the peripheral circulation and is mainly composed of endothelial cells connected by tight junctions. We examined the effects of several highly-chlorinated PCB congeners on expression ...

  19. The SAURON project - X. The orbital anisotropy of elliptical and lenticular galaxies : revisiting the (V/sigma,epsilon) diagram with integral-field stellar kinematics

    NARCIS (Netherlands)

    Cappellari, Michele; Emsellem, Eric; Bacon, R.; Bureau, M.; Davies, Roger L.; de Zeeuw, P. T.; Falcon-Barroso, Jesus; Krajnovic, Davor; Kuntschner, Harald; McDermid, Richard M.; Peletier, Reynier F.; Sarzi, Marc; van den Bosch, Remco C. E.; van de Ven, Glenn

    2007-01-01

    We analyse the orbital distribution of elliptical (E) and lenticular (S0) galaxies using SAURON integral-field stellar kinematics within about one effective (half-light) radius. We construct the anisotropy diagram, which relates the ratio of the ordered and random motion in a galaxy (V/sigma) to its

  20. Investigation of an optical method for determining the average radius of curvature of micro-optical lenticular lens arrays

    DEFF Research Database (Denmark)

    Iversen, Theis Faber Quist; Hanson, Steen Grüner; Kirkegaard, Peter

    2009-01-01

    variations that have arisen in the moulding process. The experimental results are compared with a model, based on the Fraunhofer approximation to the Huygens-Fresnel principle. Furthermore, the optical elements under investigation are probed using a scanning probe microscope. Hence, access to accurate......Micro-optical elements are of great importance in areas of optoelectronics and information processing. Establishing fast, reliable methods for characterization and quality control of these elements is important in order to maintain the optical performance in a high volume production process. We...... investigate an optical technique, applied to a polymer-based, injection moulded, lenticular array, but the method is also applicable for the tooling for these elements. The cylindrical lenses have feature sizes of 1-15 mu m. The method is based on observation of the intensity distribution, which can...

  1. Diagnosing the tight building syndrome

    Energy Technology Data Exchange (ETDEWEB)

    Rogers, S.A.

    1987-12-01

    Formaldehyde is but one of many chemicals capable of causing the tight building syndrome or environmentally induced illness (EI). The spectrum of symptoms it may induce includes attacks of headache, flushing, laryngitis, dizziness, nausea, extreme weakness, arthralgia, unwarranted depression, dysphonia, exhaustion, inability to think clearly, arrhythmia or muscle spasms. The nonspecificity of such symptoms can baffle physicians from many specialties. Presented herein is a simple office method for demonstrating that formaldehyde is among the etiologic agents triggering these symptoms. The very symptoms that patients complain of can be provoked within minutes, and subsequently abolished, with an intradermal injection of the appropriate strength of formaldehyde. This injection aids in convincing the patient of the cause of the symptoms so he can initiate measure to bring his disease under control.

  2. Invasive tightly coupled processor arrays

    CERN Document Server

    LARI, VAHID

    2016-01-01

    This book introduces new massively parallel computer (MPSoC) architectures called invasive tightly coupled processor arrays. It proposes strategies, architecture designs, and programming interfaces for invasive TCPAs that allow invading and subsequently executing loop programs with strict requirements or guarantees of non-functional execution qualities such as performance, power consumption, and reliability. For the first time, such a configurable processor array architecture consisting of locally interconnected VLIW processing elements can be claimed by programs, either in full or in part, using the principle of invasive computing. Invasive TCPAs provide unprecedented energy efficiency for the parallel execution of nested loop programs by avoiding any global memory access such as GPUs and may even support loops with complex dependencies such as loop-carried dependencies that are not amenable to parallel execution on GPUs. For this purpose, the book proposes different invasion strategies for claiming a desire...

  3. The ATLAS3D project - XXVII. Cold gas and the colours and ages of early-type galaxies

    NARCIS (Netherlands)

    Young, Lisa M.; Scott, Nicholas; Serra, Paolo; Alatalo, Katherine; Bayet, Estelle; Blitz, Leo; Bois, Maxime; Bournaud, Frédéric; Bureau, Martin; Crocker, Alison F.; Cappellari, Michele; Davies, Roger L.; Davis, Timothy A.; de Zeeuw, P. T.; Duc, Pierre-Alain; Emsellem, Eric; Khochfar, Sadegh; Krajnović, Davor; Kuntschner, Harald; McDermid, Richard M.; Morganti, Raffaella; Naab, Thorsten; Oosterloo, Tom; Sarzi, Marc; Weijmans, Anne-Marie

    2014-01-01

    We present a study of the cold gas contents of the ATLAS3D early-type galaxies, in the context of their optical colours, near-ultraviolet colours and Hβ absorption line strengths. Early-type (elliptical and lenticular) galaxies are not as gas poor as previously thought, and at least 40 per cent of

  4. Tightly Secure Signatures From Lossy Identification Schemes

    OpenAIRE

    Abdalla , Michel; Fouque , Pierre-Alain; Lyubashevsky , Vadim; Tibouchi , Mehdi

    2015-01-01

    International audience; In this paper, we present three digital signature schemes with tight security reductions in the random oracle model. Our first signature scheme is a particularly efficient version of the short exponent discrete log-based scheme of Girault et al. (J Cryptol 19(4):463–487, 2006). Our scheme has a tight reduction to the decisional short discrete logarithm problem, while still maintaining the non-tight reduction to the computational version of the problem upon which the or...

  5. Global Coal Trade. From Tightness to Oversupply

    International Nuclear Information System (INIS)

    Cornot-Gandolphe, Sylvie

    2013-01-01

    Over the past four years, international coal trade has been reshaped by China's surging imports. China, which was still a net exporter in 2008, became the world's first coal importer in 2011, taking over the position that Japan has occupied for three decades. Its imports have continued their rising trend and reached a record level in 2012, despite the country's economic slowdown. China imported 289 million tons of coal in 2012, up 30% over 2011. It now accounts for 23% of global imports. Although China is the world's largest coal producer, several factors have contributed to the sudden rise in its imports, including the higher cost of domestic coal relative to international prices and bottlenecks in transporting domestic coal to south-eastern provinces. More recently, another event shook the international coal business: the United States have been back on the market. The collapse of U.S. gas prices, to $4/million Btu in 2011 and even $2.75/million Btu in 2012, linked with the 'shale gas revolution', has made coal uncompetitive in the electricity sector, its main outlet on the U.S. market. U.S. coal demand dropped 4% in 2011 and 11% in 2012. The reduction in domestic demand has forced U.S. miners to look for overseas outlets. Their exports surged by 31% in 2011 and 16% in 2012. They reached 112 million tons in 2012, more than twice the level of 2009. The United States, which almost disappeared from the international steam coal market in the 2000's, have regained a larger share of the total coal export market, 9% in 2012, against 6% in 2009. These developments, although not directly linked, have a huge impact on the global market and pricing of coal. Chinese imports have helped the market to quickly recover from its low level of 2008-2009. The speed and magnitude of China's coal imports even shifts the market from a sluggish to a tight situation. Prices started to rise after their collapse in the second half of 2008 caused by the economic and financial crisis

  6. Polyphenols of Cassia tora leaves prevents lenticular apoptosis and modulates cataract pathology in Sprague-Dawley rat pups.

    Science.gov (United States)

    Sreelakshmi, V; Abraham, Annie

    2016-07-01

    Cataract is a leading cause of visual impairment worldwide with multifactorial etiology and is a significant global health problem with increasing prevalence with age. Currently, no pharmacological measures are discovered to prevent and treat cataract and a significant number of epidemiological studies have suggested the potential role of antioxidants in the prevention of cataract by scavenging free radicals and preventing lens protein derangement and lenticular cell damage. The main goal of the present study is to evaluate Cassia tora leaves; an edible leafy vegetable employed in Ayurvedic and Chinese system of medicine for eye rejuvenation in preventing selenite-induced cataract in rat pups and to identify the active components that produce the effect. ECT pre-treatment effectively restored both enzymatic and metabolic antioxidant levels, membrane integrity and reduced metal accumulation and thus down-regulate epithelial cell death. Gene expression studies also confirmed these findings. ESI-MS analysis of ECT revealed the presence of chrysophanol, emodin, kaemferol, quercetin, stigmasterol and isoquercetin. The study suggests the possible role of C. tora in alleviating cataract pathology and presence of many anthraquinones and flavonoids. As it is an edible plant, the incorporation of these leaves in daily vegetables might prevent or delay the onset and maturation of cataract. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  7. Gas

    International Nuclear Information System (INIS)

    1996-01-01

    The French government has decided to modify the conditions of extension of local natural gas authorities to neighbouring districts. The European Union is studying the conditions of internal gas market with the objective of more open markets although considering public service requirements

  8. The tight reservoir microscopic classification of southern part of Qijia area in Songliao Basin

    Science.gov (United States)

    Hang, Fu

    2018-02-01

    With the decreasing of the conventional oil and gas reserves, the unconventional tight oil and gas are gradually becoming the focus of the study. The casting thin section, conventional mercury injection, constant velocity and pressure mercury and other experimental methods, tight reservoir microscopic characteristics in southern part of Qijia area were studied in this paper. Based on the above conditions, combined with the parameters of pore type, pore throat radius, the reservoir is divided into two types, conventional reservoir and low permeability tight reservoir. Reservoir conventional reservoir permeability values are greater than 1mD, low permeability tight reservoirs are classified into IIa type and IIb type, which provides some reference value for the actual exploration and development.

  9. Appraisal of the tight sands potential of the Sand Wash and Great Divide Basins

    International Nuclear Information System (INIS)

    1993-08-01

    The volume of future tight gas reserve additions is difficult to estimate because of uncertainties in the characterization and extent of the resource and the performance and cost-effectiveness of stimulation and production technologies. Ongoing R ampersand D by industry and government aims to reduce the risks and costs of producing these tight resources, increase the certainty of knowledge of their geologic characteristics and extent, and increase the efficiency of production technologies. Some basins expected to contain large volumes of tight gas are being evaluated as to their potential contribution to domestic gas supplies. This report describes the results of one such appraisal. This analysis addresses the tight portions of the Eastern Greater Green River Basin (Sand Wash and Great Divide Subbasins in Northwestern Colorado and Southwestern Wyoming, respectively), with respect to estimated gas-in-place, technical recovery, and potential reserves. Geological data were compiled from public and proprietary sources. The study estimated gas-in-place in significant (greater than 10 feet net sand thickness) tight sand intervals for six distinct vertical and 21 areal units of analysis. These units of analysis represent tight gas potential outside current areas of development. For each unit of analysis, a ''typical'' well was modeled to represent the costs, recovery and economics of near-term drilling prospects in that unit. Technically recoverable gas was calculated using reservoir properties and assumptions about current formation evaluation and extraction technology performance. Basin-specific capital and operating costs were incorporated along with taxes, royalties and current regulations to estimate the minimum required wellhead gas price required to make the typical well in each of unit of analysis economic

  10. Intensive Insulin Therapy: Tight Blood Sugar Control

    Science.gov (United States)

    Intensive insulin therapy: Tight blood sugar control Intensive insulin therapy can help prevent long-term diabetes complications. Consider the ... cases if you have type 2 diabetes — intensive insulin therapy may be the key to long-term ...

  11. unconventional natural gas reservoirs

    International Nuclear Information System (INIS)

    Correa G, Tomas F; Osorio, Nelson; Restrepo R, Dora P

    2009-01-01

    This work is an exploration about different unconventional gas reservoirs worldwide: coal bed methane, tight gas, shale gas and gas hydrate? describing aspects such as definition, reserves, production methods, environmental issues and economics. The overview also mentioned preliminary studies about these sources in Colombia.

  12. Diagenesis and Fluid Flow Variability of Structural Heterogeneity Units in Tight Sandstone Carrier Beds of Dibei, Eastern Kuqa Depression

    Directory of Open Access Journals (Sweden)

    H. Shi

    2017-01-01

    Full Text Available Tight sand gas plays an important role in the supply of natural gas production. It has significance for predicting sweet spots to recognize the characteristics and forming of heterogeneity in tight sandstone carrier beds. Heterogeneity responsible for spatial structure, such as the combination and distribution of relatively homogeneous rock layers, is basically established by deposition and eodiagenesis that collectively affect the mesogenesis. We have investigated the structural heterogeneity units by petrofacies in tight sandstone carrier beds of Dibei, eastern Kuqa Depression, according to core, logging, and micropetrology. There are four types of main petrofacies, that is, tight compacted, tight carbonate-cemented, gas-bearing, and water-bearing sandstones. The brine-rock-hydrocarbon diagenesis changes of different heterogeneity structural units have been determined according to the pore bitumen, hydrocarbon inclusions, and quantitative grain fluorescence. Ductile grains or eogenetic calcite cements destroy the reservoir quality of tight compacted or tight carbonate-cemented sandstones. Rigid grains can resist mechanical compaction and oil emplacement before gas charging can inhibit diagenesis to preserve reservoir property of other sandstones. We propose that there is an inheritance relationship between the late gas and early oil migration pathways, which implies that the sweet spots develop in the reservoirs that experienced early oil emplacement.

  13. Flow and Transport in Tight and Shale Formations: A Review

    Directory of Open Access Journals (Sweden)

    Amgad Salama

    2017-01-01

    Full Text Available A review on the recent advances of the flow and transport phenomena in tight and shale formations is presented in this work. Exploration of oil and gas in resources that were once considered inaccessible opened the door to highlight interesting phenomena that require attention and understanding. The length scales associated with transport phenomena in tight and shale formations are rich. From nanoscale phenomena to field-scale applications, a unified frame that is able to encounter the varieties of phenomena associated with each scale may not be possible. Each scale has its own tools and limitations that may not, probably, be suitable at other scales. Multiscale algorithms that effectively couple simulations among various scales of porous media are therefore important. In this article, a review of the different length scales and the tools associated with each scale is introduced. Highlights on the different phenomena pertinent to each scale are summarized. Furthermore, the governing equations describing flow and transport phenomena at different scales are investigated. In addition, methods to solve these equations using numerical techniques are introduced. Cross-scale analysis and derivation of linear and nonlinear Darcy’s scale laws from pore-scale governing equations are described. Phenomena occurring at molecular scales and their thermodynamics are discussed. Flow slippage at the nanosize pores and its upscaling to Darcy’s scale are highlighted. Pore network models are discussed as a viable tool to estimate macroscopic parameters that are otherwise difficult to measure. Then, the environmental aspects associated with the different technologies used in stimulating the gas stored in tight and shale formations are briefly discussed.

  14. Flow and Transport in Tight and Shale Formations: A Review

    KAUST Repository

    Salama, Amgad

    2017-09-18

    A review on the recent advances of the flow and transport phenomena in tight and shale formations is presented in this work. Exploration of oil and gas in resources that were once considered inaccessible opened the door to highlight interesting phenomena that require attention and understanding. The length scales associated with transport phenomena in tight and shale formations are rich. From nanoscale phenomena to field-scale applications, a unified frame that is able to encounter the varieties of phenomena associated with each scale may not be possible. Each scale has its own tools and limitations that may not, probably, be suitable at other scales. Multiscale algorithms that effectively couple simulations among various scales of porous media are therefore important. In this article, a review of the different length scales and the tools associated with each scale is introduced. Highlights on the different phenomena pertinent to each scale are summarized. Furthermore, the governing equations describing flow and transport phenomena at different scales are investigated. In addition, methods to solve these equations using numerical techniques are introduced. Cross-scale analysis and derivation of linear and nonlinear Darcy\\'s scale laws from pore-scale governing equations are described. Phenomena occurring at molecular scales and their thermodynamics are discussed. Flow slippage at the nanosize pores and its upscaling to Darcy\\'s scale are highlighted. Pore network models are discussed as a viable tool to estimate macroscopic parameters that are otherwise difficult to measure. Then, the environmental aspects associated with the different technologies used in stimulating the gas stored in tight and shale formations are briefly discussed.

  15. Tight rock fracturing due to internal gas production

    Science.gov (United States)

    Kobchenko, M.; Dysthe, D. K.; Renard, F.; Galland, O.

    2012-04-01

    Dehydration of sediments in subduction zones, magma emplacements, primary migration of hydrocarbons from organic-rich shales, venting involve the generation and migration of fluids in low permeability rocks. In all these geological systems, the migration of fluid through rock matrix is coupled with deformation. Generated fluid causes pressure build-up and leads to fracturing. Cracks grow, coalesce and form network, providing escaping pathways for outgoing fluids. We use gelatin to study the main characteristics of this process. We model fluid production by mixing gelatin with yeast, which generates CO2. The system exhibit a complex dynamics with clear fracture-fracture interactions. The conduct experiments in a Hele-Shaw cell, allowing us to monitor the formation, growth and intermittent connection of cracks within the gelatin through time. Although the gelatin media does not perfectly reproduce rock properties, it helps understanding basic principles of fracturing of a low permeability elastic medium, induced by in-situ fluid pressure generation.

  16. Boundary effect on liquid invasion in tight gas reservoirs

    Directory of Open Access Journals (Sweden)

    Li Gao

    2015-01-01

    Full Text Available Liquid invasion is an important transport phenomenon in many geophysical and environmental applications. A new capillary model considering boundary effect is proposed to reveal its mechanism. The boundary fluid layer not only reduces the effective flow radius, but also changes the viscosity of fluid. Thus the capillary force and viscosity resistance increases, however, the increase of capillary force is faster than that of viscosity resistance, therefore the invasion front arrives at the critical distance earlier.

  17. Critical Power Performance of Tight Lattice Bundle

    Science.gov (United States)

    Yamamoto, Yasushi; Hiraiwa, Kouji; Morooka, Shinichi; Abe, Nobuaki

    An innovative fuel cycle system concept named BARS (BWR with an Advanced Recycle System) has been proposed as a future fuel cycle option aiming at enhanced utilization of uranium resources and reduction of radioactive wastes. In BARS, the spent fuel from conventional light water reactors (LWRs) is recycled as a mixed oxide (MOX) fuel for a BWR core with the fast neutron spectrum by means of oxide dry-processing and vibro-packing fuel fabrication. The fast neutron spectrum is obtained by means of triangular tight fuel lattice. Further study on BARS, especially on tight lattice MOX fuel, has been initiated as a joint study by Toshiba and Gifu University. The objective of this paper is to show the latest progress of the study on BARS, especially concerning the thermal-hydraulics measurements for tight lattice bundle.

  18. An introduction to finite tight frames

    CERN Document Server

    Waldron, Shayne F D

    2018-01-01

    This textbook is an introduction to the theory and applications of finite tight frames, an area that has developed rapidly in the last decade. Stimulating much of this growth are the applications of finite frames to diverse fields such as signal processing, quantum information theory, multivariate orthogonal polynomials, and remote sensing. Key features and topics: * First book entirely devoted to finite frames * Extensive exercises and MATLAB examples for classroom use * Important examples, such as harmonic and Heisenberg frames, are presented in preliminary chapters, encouraging readers to explore and develop an intuitive feeling for tight frames * Later chapters delve into general theory details and recent research results * Many illustrations showing the special aspects of the geometry of finite frames * Provides an overview of the field of finite tight frames * Discusses future research directions in the field Featuring exercises and MATLAB examples in each chapter, the book is well suited as a textbook ...

  19. Hermetic compartments leak-tightness enhancement

    International Nuclear Information System (INIS)

    Murani, J.

    2000-01-01

    In connection with the enhancement of the nuclear safety of the Jaslovske Bohunice V-1 NPP actions for the increase of the leak tightness are performed. The reconstruction has been done in the following directions: hermetic compartments leak tightness enhancement; air lock installation; installation of air lock in SP 4 vent system; integrated leakage rate test to hermetic compartments with leak detection. After 'major' leaks on the hermetic boundary components had been eliminated, since 1994 works on a higher qualitative level began. The essence of the works consists in the detection and identification of leaks in the structural component of the hermetic boundary during the planned refueling outages. The results of the Small Reconstruction and gradual enhancement of leak tightness are presented

  20. Absolute tightness: the chemists hesitate to invest

    International Nuclear Information System (INIS)

    Anon.

    1996-01-01

    The safety requirements of industries as nuclear plants and the strengthening of regulations in the field of environment (more particularly those related to volatile organic compounds) have lead the manufacturers to build absolute tightness pumps. But these equipments do not answer all the problems and represent a high investment cost. In consequence, the chemists hesitate to invest. (O.L.)

  1. Tight-binding treatment of conjugated polymers

    DEFF Research Database (Denmark)

    Lynge, Thomas Bastholm

    This PhD thesis concerns conjugated polymers which constitute a constantly growing research area. Today, among other things, conjugated polymers play a role in plastic based solar cells, photodetectors and light emitting diodes, and even today such plastic-based components constitute an alternative...... of tomorrow. This thesis specifically treats the three conjugated polymers trans-polyacetylene (tPA), poly(para-phenylene) (PPP) and poly(para-phe\\-nylene vinylene) (PPV). The present results, which are derived within the tight-binding model, are divided into two parts. In one part, analytic results...... are derived for the optical properties of the polymers expressed in terms of the optical susceptibility both in the presence and in the absence of a static electric field. In the other part, the cumputationally efficient Density Functional-based Tight-Binding (DFTB) model is applied to the description...

  2. Equiangular tight frames and unistochastic matrices

    Czech Academy of Sciences Publication Activity Database

    Goyeneche, D.; Turek, Ondřej

    2017-01-01

    Roč. 50, č. 24 (2017), č. článku 245304. ISSN 1751-8113 R&D Projects: GA ČR GA17-01706S Institutional support: RVO:61389005 Keywords : equiangular tight frames * unistochastic matrices * SIC POVM Subject RIV: BE - Theoretical Physics OBOR OECD: Atomic, molecular and chemical physics (physics of atoms and molecules including collision, interaction with radiation, magnetic resonances, Mössbauer effect) Impact factor: 1.857, year: 2016

  3. Terrestrial tight oil reservoir characteristics and Graded Resource Assessment in China

    Science.gov (United States)

    Wang, Shejiao; Wu, Xiaozhi; Guo, Giulin

    2016-04-01

    China. The porosity is 2-14%(average 5-10%)and the permeability is less than 1mD. The laboratory test and exploration practice confirmed that the oil content was positively related to physical property. The higher the porosity, the better the oil content will have. (3) Source rock and reservoir are superimposed. From the contact relationship of source rock and reservoir, the reservoir developed in the source rock has the advantage of capturing oil and gas, so the oil saturation can be as high as 70-80%. (4) The increased pressure caused by hydrocarbon generation and the connected fracture are the key factors for tight oil accumulation. The Fuyu tight oil formed underling source rock in Songliao Basin is a good example. The fracture system is the key factor for tight oil accumulation. Considering the strong heterogeneity of terrestrial tight oil reservoir in china, we create hierarchical resource abundance analogy, EUR analogy, cell element volumetric methods to evaluate tight oil resource potential. In order to find exploration "sweet spots", establishing tight oil resource classification evaluation standards are key steps to objectively evaluate tight oil resource distribution. The resource classification evaluation standards are established by the relationship analysis between reservoir properties and oil properties, and the correlation analysis between production, resource abundance, and reservoir thickness. The first-grade tight oil resource, which is recently available and can easily be developed, has following main parameters: the porosity is greater than 8%, thickness is over 10m, resource abundance is above 150,000 tons / km2, and pressure coefficient is greater than 1.3; The second-grade tight oil resource is currently unavailable, but with advanced technology can expected to be developed. The main parameters are as following: the porosity is 5% -8%, thickness is less than 5-10m, resource abundance is 50000-150000 tons / km2, the pressure coefficient is 1.0 to

  4. Tight Reference Frame–Independent Quantum Teleportation

    Directory of Open Access Journals (Sweden)

    Dominic Verdon

    2017-01-01

    Full Text Available We give a tight scheme for teleporting a quantum state between two parties whose reference frames are misaligned by an action of a finite symmetry group. Unlike previously proposed schemes, ours requires no additional tokens or data to be passed between the participants; the same amount of classical information is transferred as for ordinary quantum teleportation, and the Hilbert space of the entangled resource is of the same size. In the terminology of Peres and Scudo, our protocol relies on classical communication of unspeakable information.

  5. Inward Leakage in Tight-Fitting PAPRs

    Directory of Open Access Journals (Sweden)

    Frank C. Koh

    2011-01-01

    Full Text Available A combination of local flow measurement techniques and fog flow visualization was used to determine the inward leakage for two tight-fitting powered air-purifying respirators (PAPRs, the 3M Breathe-Easy PAPR and the SE 400 breathing demand PAPR. The PAPRs were mounted on a breathing machine head form, and flows were measured from the blower and into the breathing machine. Both respirators leaked a little at the beginning of inhalation, probably through their exhalation valves. In both cases, the leakage was not enough for fog to appear at the mouth of the head form.

  6. DISTRIBUTION AND MOTIONS OF ATOMIC-HYDROGEN IN LENTICULAR GALAXIES .10. THE BLUE S0-GALAXY NGC-5102

    NARCIS (Netherlands)

    VANWOERDEN, H; VANDRIEL, W; BRAUN, R; ROTS, AH

    We have mapped the blue gas-rich S0 galaxy NGC 5102 in the 21-cm HI line with a spatial resolution of 34'' x 37'' (DELTAalpha x DELTAdelta) and a velocity resolution of 12 km s-1. Optically NGC 5102 is a peculiar S0 galaxy, in the sense that it has unusually blue colours, and shows evidence for a

  7. Laboratory Measurement and Interpretation of the Changes of Physical Properties after Heat Treatment in Tight Porous Media

    Directory of Open Access Journals (Sweden)

    Yili Kang

    2015-01-01

    Full Text Available Prevention of water blocking and optimization of multiscale flow channels will increase gas production of tight reservoirs. Physical properties of samples from representative tight gas reservoirs were measured before and after high temperature treatment. Results show that, with the increase of treatment temperature, mass decreases, acoustic transit time increases, and permeability and porosity increase. Permeability begins to increase dramatically if treatment temperature exceeds the threshold value of thermal fracturing, which is 600~700°C, 500~600°C, 300~500°C, and 300~400°C for shale, mudstone, tight sandstone, and tight carbonate rock, respectively. Comprehensive analyses indicate that the mechanisms of heat treatment on tight porous media include evaporation and dehydration of water, change of mineral structure, generation of microfracture, and network connectivity. Meanwhile, field implementation is reviewed and prospected. Interpretations indicate that, according to the characteristics of multiscale mass transfer in tight gas formation, combining heat treatment with conventional stimulation methods can achieve the best stimulation result.

  8. The effect of fluid saturation on the dynamic shear modulus of tight sandstones

    Science.gov (United States)

    Li, Dongqing; Wei, Jianxin; Di, Bangrang; Ding, Pinbo; Shuai, Da

    2017-10-01

    Tight sandstones have become important targets in the exploration of unconventional oil and gas reservoirs. However, due to low porosity, low permeability, complex pore structure and other petrophysical properties of tight sandstones, the applicability of Gassmann’s fluid substitution procedure becomes debatable. Aiming at this problem, this paper attempts to explore the applicability of Gassmann’s theory in tight sandstones. Our focus is to investigate the sensitivity of dynamic shear modulus to fluid saturation and the possible mechanism. Ultrasonic velocity in dry and saturated tight sandstone samples was measured in the laboratory under an effective pressure within the range of 1-60 MPa. This study shows that the shear modulus of the water-saturated samples appears to either increase or decrease, and the soft porosity model (SPM) can be used to quantitatively estimate the variation of shear modulus. Under the condition of in situ pressure, samples dominated by secondary pores and microcracks are prone to show shear strengthening with saturation, which is possibly attributed to the local flow dispersion. Samples that mainly have primary pores are more likely to show shear weakening with saturation, which can be explained by the surface energy mechanism. We also find good correlation between changes in shear modulus and inaccurate Gassmann-predicted saturated velocity. Therefore, understanding the variation of shear modulus is helpful to improving the applicability of Gassmann’s theory in tight sandstones.

  9. An Integrated Rock Typing Approach for Unraveling the Reservoir Heterogeneity of Tight Sands in the Whicher Range Field of Perth Basin, Western Australia

    DEFF Research Database (Denmark)

    Ilkhchi, Rahim Kadkhodaie; Rezaee, Reza; Harami, Reza Moussavi

    2014-01-01

    Tight gas sands in Whicher Range Field of Perth Basin show large heterogeneity in reservoir characteristics and production behavior related to depositional and diagenetic features. Diagenetic events (compaction and cementation) have severely affected the pore system. In order to investigate...... the petrophysical characteristics, reservoir sandstone facies were correlated with core porosity and permeability and their equivalent well log responses to describe hydraulic flow units and electrofacies, respectively. Thus, very tight, tight, and sub-tight sands were differentiated. To reveal the relationship......, diagenetic features and petrophysical characteristics) is a suitable technique for depiction of reservoir heterogeneity, recognition of reservoir units and identifying factors controlling reservoir quality of tight sandstones. This methodology can be used for the other tight reservoirs....

  10. Gas separation membrane module assembly

    Science.gov (United States)

    Wynn, Nicholas P [Palo Alto, CA; Fulton, Donald A [Fairfield, CA

    2009-03-31

    A gas-separation membrane module assembly and a gas-separation process using the assembly. The assembly includes a set of tubes, each containing gas-separation membranes, arranged within a housing. The housing contains a tube sheet that divides the space within the housing into two gas-tight spaces. A permeate collection system within the housing gathers permeate gas from the tubes for discharge from the housing.

  11. Experience in North America Tight Oil Reserves Development. Horizontal Wells and Multistage Hydraulic Fracturing

    Directory of Open Access Journals (Sweden)

    R.R. Ibatullin

    2017-09-01

    Full Text Available The accelerated development of horizontal drilling technology in combination with the multistage hydraulic fracturing of the reservoir has expanded the geological conditions for commercial oil production from tight reservoirs in North America. Geological and physical characteristics of tight reservoirs in North America are presented, as well as a comparison of the geological and physical properties of the reservoirs of the Western Canadian Sedimentary Basin and the Volga-Ural oil and gas province, in particular, in the territory of Tatarstan. The similarity of these basins is shown in terms of formation and deposition. New drilling technologies for horizontal wells (HW and multistage hydraulic fracturing are considered. The drilling in tight reservoirs is carried out exclusively on hydrocarbon-based muds The multi-stage fracturing technology with the use of sliding sleeves, and also slick water – a low-viscous carrier for proppant is the most effective solution for conditions similar to tight reservoirs in the Devonian formation of Tatarstan. Tax incentives which are actively used for the development of HW and multistage fracturing technologies in Canada are described. wells, multistage fracturing

  12. Digital Rock Studies of Tight Porous Media

    Energy Technology Data Exchange (ETDEWEB)

    Silin, Dmitriy [Lawrence Berkeley National Lab. (LBNL), Berkeley, CA (United States)

    2012-08-07

    This technical report summarizes some recently developed approaches to studies of rock properties at a pore scale. Digital rock approach is complementary to laboratory and field studies. It can be especially helpful in situations where experimental data are uncertain, or are difficult or impossible to obtain. Digitized binary images of the pore geometries of natural rocks obtained by different imaging techniques are the input data. Computer-generated models of natural rocks can be used instead of images in a case where microtomography data are unavailable, or the resolution of the tools is insufficient to adequately characterize the features of interest. Simulations of creeping viscous flow in pores produce estimates of Darcy permeability. Maximal Inscribed Spheres calculations estimate two-phase fluid distribution in capillary equilibrium. A combination of both produce relative permeability curves. Computer-generated rock models were employed to study two-phase properties of fractured rocks, or tight sands with slit-like pores, too narrow to be characterized with micro-tomography. Various scenarios can simulate different fluid displacement mechanisms, from piston-like drainage to liquid dropout at the dew point. A finite differences discretization of Stokes equation is developed to simulate flow in the pore space of natural rocks. The numerical schemes are capable to handle both no-slip and slippage flows. An upscaling procedure estimates the permeability by subsampling a large data set. Capillary equilibrium and capillary pressure curves are efficiently estimated with the method of maximal inscribed spheres both an arbitrary contact angle. The algorithms can handle gigobytes of data on a desktop workstation. Customized QuickHull algorithms model natural rocks. Capillary pressure curves evaluated from computer-generated images mimic those obtained for microtomography data.

  13. Generic assessment of tight-fitting annulus spacer mobility

    International Nuclear Information System (INIS)

    Robertson, J.; Micuda, L.; Van Den Brekel, N.

    2006-01-01

    This paper provides a generic assessment of the mobility of tight-fitting fuel channel annulus spacers in OPG and Bruce Power nuclear units. This assessment is applicable to all tight-fitting annulus spacers, including those used in the original fuel channel installation (Darlington Units 1-4, retubed Pickering Units 1-4, and Bruce Unit 8) and as a result of single fuel channel replacements (SFCR) (Pickering Units 5-8, Bruce Units 3-7). Tight-fitting annulus spacers were designed not to move. Pressure tube to calandria tube contact analyses, and the associated blister susceptibility assessments, have assumed that these tight-fitting spacers remain at the pre-service installed locations. Given the importance of this assumption, the technical basis for the expectation that tight-fitting annulus spacers do not move significantly from their pre-service locations, relative to the pressure tube, was reviewed in detail. The review also assessed the inspection data, comparing spacer locations from in-service and pre-service inspections. The review has concluded that tight-fitting spacers do not move sufficiently to necessitate a postulated spacer movement in fuel channel contact analyses. The paper describes the background of this issue, briefly reviews the experimental programs used to qualify the positional stability of the tight-fitting spacer design, and evaluates the current database of in-service spacer location inspection information to demonstrate that no significant movement relative to the pressure tube has been observed. (author)

  14. METHOD FOR CALCULATION OF DISPLACEMENT FIELDS AND STRESSES IN SYSTEM OF PARALLEL LENTICULAR MECHANICAL TWINS OCCURRING IN MARTENSITIC PHASE OF Ni2MnGa-MAGNETIC ALLOY HAVING PROPERTY OF SHAPE MEMORY

    Directory of Open Access Journals (Sweden)

    E. V. Shmatok

    2015-01-01

    Full Text Available Nowadays mathematical modeling of peculiar features of a stress-strain state is considered as a perspective direction of research. In this regard the aim of this paper has been to make calculations of the stress-strain state initiated by a system of parallel lenticular residual mechanical twins that occur due to local surface deformation of  Ni2MnGa single crystal martensitic phase.The method is applied while using a superposition principle of fields and approximation of a continuous distribution of twinning dislocations on twin boundaries in a continuous elastic medium.The calculations have made it possible to obtain distribution graphs of displacement fields and stresses and point out the fact that a configuration of displacement component distribution uy is significantly different from the displacement of components ux and uz having a displacement distribution similar to each other. The highest value of displacement occurs in the component uy in twins peaks.The paper also presents results of calculations for six components of a stress field the tensor. The obtained results have revealed similarity in stress distribution character of the components  sxz and szz, but they differ numerically from each other about in two times. The largest value of the stresses occurring in the lenticular twins has been observed in components sxx, sxz, syy, syz and it has been focused mainly at the borders and peaks  of twins.A common feature of the obtained components of displacement and stresses in a lenticular twins system is symmetry with regard to OY. In addition, the stress distribution of all obtained tensor components has been mainly localized at the borders and at the tops of twins where the highest values of stresses capable of exerting a significant impact on dislocation and diffusion processes are generally concentrated.

  15. Diagenesis and porosity evolution of tight sand reservoirs in Carboniferous Benxi Formation, Southeast Ordos Basin

    Science.gov (United States)

    Hu, Peng; Yu, Xinghe; Shan, Xin; Su, Dongxu; Wang, Jiao; Li, Yalong; Shi, Xin; Xu, Liqiang

    2016-04-01

    The Ordos Basin, situated in west-central China, is one of the oldest and most important fossil-fuel energy base, which contains large reserves of coal, oil and natural gas. The Upper Palaeozoic strata are widely distributed with rich gas-bearing and large natural gas resources, whose potential is tremendous. Recent years have witnessed a great tight gas exploration improvement of the Upper Paleozoic in Southeastern Ordos basin. The Carboniferous Benxi Formation, mainly buried more than 2,500m, is the key target strata for hydrocarbon exploration, which was deposited in a barrier island and tidal flat environment. The sandy bars and flats are the favorable sedimentary microfacies. With an integrated approach of thin-section petrophysics, constant velocity mercury injection test, scanning electron microscopy and X-ray diffractometry, diagenesis and porosity evolution of tight sand reservoirs of Benxi Formation were analyzed in detail. The result shows that the main lithology of sandstone in this area is dominated by moderately to well sorted quartz sandstone. The average porosity and permeability is 4.72% and 1.22mD. The reservoirs of Benxi Formation holds a variety of pore types and the pore throats, with obvious heterogeneity and poor connection. Based on the capillary pressure curve morphological characteristics and parameters, combined with thin section and phycical property data, the reservoir pore structure of Benxi Formation can be divided into 4 types, including mid pore mid throat type(I), mid pore fine throat type(II), small pore fine throat type(III) and micro pro micro throat type(Ⅳ). The reservoirs primarily fall in B-subsate of middle diagenesis and late diagenesis, which mainly undergo compaction, cmentation, dissolution and fracturing process. Employing the empirical formula of different sorting for unconsolideated sandstone porosity, the initial sandstone porosity is 38.32% on average. Quantitative evaluation of the increase and decrease of

  16. Fracking in Tight Shales: What Is It, What Does It Accomplish, and What Are Its Consequences?

    Science.gov (United States)

    Norris, J. Quinn; Turcotte, Donald L.; Moores, Eldridge M.; Brodsky, Emily E.; Rundle, John B.

    2016-06-01

    Fracking is a popular term referring to hydraulic fracturing when it is used to extract hydrocarbons. We distinguish between low-volume traditional fracking and the high-volume modern fracking used to recover large volumes of hydrocarbons from shales. Shales are fine-grained rocks with low granular permeabilities. During the formation of oil and gas, large fluid pressures are generated. These pressures result in natural fracking, and the resulting fracture permeability allows oil and gas to escape, reducing the fluid pressures. These fractures may subsequently be sealed by mineral deposition, resulting in tight shale formations. The objective of modern fracking is to reopen these fractures and/or create new fractures on a wide range of scales. Modern fracking has had a major impact on the availability of oil and gas globally; however, there are serious environmental objections to modern fracking, which should be weighed carefully against its benefits.

  17. Improved RIP Conditions for Compressed Sensing with Coherent Tight Frames

    Directory of Open Access Journals (Sweden)

    Yao Wang

    2017-01-01

    Full Text Available This paper establishes new sufficient conditions on the restricted isometry property (RIP for compressed sensing with coherent tight frames. One of our main results shows that the RIP (adapted to D condition δk+θk,k<1 guarantees the stable recovery of all signals that are nearly k-sparse in terms of a coherent tight frame D via the l1-analysis method, which improves the existing ones in the literature.

  18. Effect of pore structure on the seepage characteristics of tight sandstone reservoirs: A case study of Upper Jurassic Penglaizhen Fm reservoirs in the western Sichuan Basin

    Directory of Open Access Journals (Sweden)

    Liqiang Sima

    2017-01-01

    Full Text Available Tight sandstone reservoirs are characterized by complex pore structures and strong heterogeneity, and their seepage characteristics are much different from those of conventional sandstone reservoirs. In this paper, the tight sandstone reservoirs of Upper Jurassic Penglaizhen Fm in western Sichuan Basin were analyzed in terms of their pore structures by using the data about physical property, mercury injection and nuclear magnetic resonance (NMR tests. Then, the seepage characteristics and the gas–water two-phase migration mechanisms and distribution of tight sandstone reservoirs with different types of pore structures in the process of hydrocarbon accumulation and development were simulated by combining the relative permeability experiment with the visual microscopic displacement model. It is shown that crotch-like viscous fingering occurs in the process of gas front advancing in reservoirs with different pore structures. The better the pore structure is, the lower the irreducible water saturation is; the higher the gas-phase relative permeability of irreducible water is, the more easily the gas reservoir can be developed. At the late stage of development, the residual gas is sealed in reservoirs in the forms of bypass, cutoff and dead end. In various reservoirs, the interference between gas and water is stronger, so gas and water tends to be produced simultaneously. The sealed gas may reduce the production rate of gas wells significantly, and the existence of water phase may reduce the gas permeability greatly; consequently, the water-bearing low-permeability tight sandstone gas reservoirs reveal serious water production, highly-difficult development and low-recovery percentage at the late stage, which have adverse impacts on the effective production and development of gas wells.

  19. The media of sociology: tight or loose translations?

    Science.gov (United States)

    Guggenheim, Michael

    2015-06-01

    Sociologists have increasingly come to recognize that the discipline has unduly privileged textual representations, but efforts to incorporate visual and other media are still only in their beginning. This paper develops an analysis of the ways objects of knowledge are translated into other media, in order to understand the visual practices of sociology and to point out unused possibilities. I argue that the discourse on visual sociology, by assuming that photographs are less objective than text, is based on an asymmetric media-determinism and on a misleading notion of objectivity. Instead, I suggest to analyse media with the concept of translations. I introduce several kinds of translations, most centrally the distinction between tight and loose ones. I show that many sciences, such as biology, focus on tight translations, using a variety of media and manipulating both research objects and representations. Sociology, in contrast, uses both tight and loose translations, but uses the latter only for texts. For visuals, sociology restricts itself to what I call 'the documentary': focusing on mechanical recording technologies without manipulating either the object of research or the representation. I conclude by discussing three rare examples of what is largely excluded in sociology: visual loose translations, visual tight translations based on non-mechanical recording technologies, and visual tight translations based on mechanical recording technologies that include the manipulation of both object and representation. © London School of Economics and Political Science 2015.

  20. Human zonulin, a potential modulator of intestinal tight junctions.

    Science.gov (United States)

    Wang, W; Uzzau, S; Goldblum, S E; Fasano, A

    2000-12-01

    Intercellular tight junctions are dynamic structures involved in vectorial transport of water and electrolytes across the intestinal epithelium. Zonula occludens toxin derived from Vibrio cholerae interacts with a specific intestinal epithelial surface receptor, with subsequent activation of a complex intracellular cascade of events that regulate tight junction permeability. We postulated that this toxin may mimic the effect of a functionally and immunologically related endogenous modulator of intestinal tight junctions. Affinity-purified anti-zonula occludens toxin antibodies and the Ussing chamber assay were used to screen for one or more mammalian zonula occludens toxin analogues in both fetal and adult human intestine. A novel protein, zonulin, was identified that induces tight junction disassembly in non-human primate intestinal epithelia mounted in Ussing chambers. Comparison of amino acids in the active zonula occludens toxin fragment and zonulin permitted the identification of the putative receptor binding domain within the N-terminal region of the two proteins. Zonulin likely plays a pivotal role in tight junction regulation during developmental, physiological, and pathological processes, including tissue morphogenesis, movement of fluid, macromolecules and leukocytes between the intestinal lumen and the interstitium, and inflammatory/autoimmune disorders.

  1. The Controls of Pore-Throat Structure on Fluid Performance in Tight Clastic Rock Reservoir: A Case from the Upper Triassic of Chang 7 Member, Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Yunlong Zhang

    2018-01-01

    Full Text Available The characteristics of porosity and permeability in tight clastic rock reservoir have significant difference from those in conventional reservoir. The increased exploitation of tight gas and oil requests further understanding of fluid performance in the nanoscale pore-throat network of the tight reservoir. Typical tight sandstone and siltstone samples from Ordos Basin were investigated, and rate-controlled mercury injection capillary pressure (RMICP and nuclear magnetic resonance (NMR were employed in this paper, combined with helium porosity and air permeability data, to analyze the impact of pore-throat structure on the storage and seepage capacity of these tight oil reservoirs, revealing the control factors of economic petroleum production. The researches indicate that, in the tight clastic rock reservoir, largest throat is the key control on the permeability and potentially dominates the movable water saturation in the reservoir. The storage capacity of the reservoir consists of effective throat and pore space. Although it has a relatively steady and significant proportion that resulted from the throats, its variation is still dominated by the effective pores. A combination parameter (ε that was established to be as an integrated characteristic of pore-throat structure shows effectively prediction of physical capability for hydrocarbon resource of the tight clastic rock reservoir.

  2. Independents add gas reserves, forego romance

    Energy Technology Data Exchange (ETDEWEB)

    Gill, D.

    1981-08-01

    Incentive pricing for low-permeability reservoirs and tax advantages for drilling them are 2 big reasons why more independents may start making a special effort to add gas reserves to their inventories. If so, it will be a change from past practices, which saw independents build up big gas positions by circumstance rather than by intention. There are always major refiners ready and willing to buy whole crude oil reservoirs from small producers, but purchasers willing to take gas fields in a single investment are few and far between. Lower-than-normal return on equity during the first 20 years, plus the heavy front-end cost of a frac necessary to produce the tight gas might dissuade independents from drilling tight gas sands, but those liabilities are offset by the higher price tight gas gets and the peculiar tax advantages of exploring for it that make a nice fit with the small operator's way of doing business.

  3. Conductance of Graphene Nanoribbon Junctions and the Tight Binding Model

    Directory of Open Access Journals (Sweden)

    Wu Y

    2011-01-01

    Full Text Available Abstract Planar carbon-based electronic devices, including metal/semiconductor junctions, transistors and interconnects, can now be formed from patterned sheets of graphene. Most simulations of charge transport within graphene-based electronic devices assume an energy band structure based on a nearest-neighbour tight binding analysis. In this paper, the energy band structure and conductance of graphene nanoribbons and metal/semiconductor junctions are obtained using a third nearest-neighbour tight binding analysis in conjunction with an efficient nonequilibrium Green's function formalism. We find significant differences in both the energy band structure and conductance obtained with the two approximations.

  4. Ultra-Tightly Coupled GNSS/INS for small UAVs

    DEFF Research Database (Denmark)

    Olesen, Daniel; Jakobsen, Jakob; Knudsen, Per

    2017-01-01

    fitted onto a small UAV. The storage of IF samples together with measurements from an Inertial Measurement Unit ( IMU) has allowed the authors to process an Ultra-Tightly Coupled ( U.T.C.) GNSS/INS solution from real data collected with a small UAV. The focus of this paper has been to investigate......This paper describes an ultra-tight integration of a Global Navigation Satellite System ( GNSS) receiver and an Inertial Navigation System ( INS) for small Unmanned Aerial Vehicles ( UAVs). The system is based on a low-cost and low-weight GNSS Intermediate Frequency ( IF) sampler which has been...

  5. Centrifugal gas separator

    International Nuclear Information System (INIS)

    Sakurai, Mitsuo.

    1970-01-01

    A centrifugal gas separator of a highly endurable construction and with improved gas sealing qualities utilizes a cylincrical elastic bellows or similar system in cooperation with a system of dynamic pressure operable gas seals as means for removing separated gases from the interior of the rotor drum, collecting the separated gases in their respective separated gas chambers defined by the corresponding bellows and their supporting stationary wall members, gas seals and rotor end caps, and means for discharging to the exterior of the surrounding cylindrical wall member the gaseous components from their respective separated gas chambers. In the vicinity of the rotary drum motor is a mixed gas chamber and means for providing the gas mixture along a co-axial passage into the rotary drum chamber. Orifices are bored into the end caps of the rotary drum to direct the separated gases into the aforementioned separated gas chambers which, through the action of the gas seals, freely slide upon the rotating drum to collect and thereafter discharge the thus separated gases. Therefore, according to the present invention, helium gas used to prevent separated gas remixture is unnecessary and, furthermore, the gas seals and elastic bellows means provide an air-tight seal superior to that of the contact sealing system of the former art. (K.J. Owens)

  6. Natural gas pricing

    International Nuclear Information System (INIS)

    Freedenthal, C.

    1993-01-01

    Natural gas pricing is the heart and soul of the gas business. Price specifically affects every phase of the industry. Too low a price will result in short supplies as seen in the mid-1970s when natural gas was scarce and in tight supply. To fully understand the pricing of this energy commodity, it is important to understand the total energy picture. In addition, the effect and impact of world and US economies, and economics in general are crucial to understanding natural gas pricing. The purpose of this presentation will be to show the parameters going into US natural gas pricing including the influence of the many outside industry factors like crude oil and coal pricing, market drivers pushing the gas industry, supply/demand parameters, risk management for buyers and sellers, and other elements involved in pricing analysis

  7. Envelopes of Sets of Measures, Tightness, and Markov Control Processes

    International Nuclear Information System (INIS)

    Gonzalez-Hernandez, J.; Hernandez-Lerma, O.

    1999-01-01

    We introduce upper and lower envelopes for sets of measures on an arbitrary topological space, which are then used to give a tightness criterion. These concepts are applied to show the existence of optimal policies for a class of Markov control processes

  8. Loosen up? Cultural tightness and national entrepreneurial activity

    NARCIS (Netherlands)

    Harms, Rainer; Groen, Arend J.

    The level of entrepreneurship between countries differs consistently. A source of this variance lies in national culture differences. Recently, the cultural dimension “tightness” has been introduced in the literature. Tightness refers to the degree to which a nation has strong norms and a low

  9. Dielectric constant of graphene-on-polarized substrate: A tight ...

    Indian Academy of Sciences (India)

    Sivabrata Sahu

    Corresponding author. E-mail: gcr@iopb.res.in. Published online 24 June 2017. Abstract. We report here a microscopic tight-binding theoretical study of the dynamic dielectric response of graphene-on-polarizable substrate with impurity. The Hamiltonian consists of first, second and third nearest- neighbour electron hopping ...

  10. Dielectric constant of graphene-on-polarized substrate: A tight ...

    Indian Academy of Sciences (India)

    2017-06-24

    Jun 24, 2017 ... We report here a microscopic tight-binding theoretical study of the dynamic dielectric response of graphene-on-polarizable substrate with impurity. The Hamiltonian consists of first, second and third nearest neighbour electron hopping interactions besides doping and substrate-induced effects on graphene.

  11. Management of Small Urethrocutaneous Fistula by Tight Ligation ...

    African Journals Online (AJOL)

    After identifying the fistulous opening, the fistula tract was circumferentially and meticulously dissected ,then the dissected tract was lifted up and the base was ligated tightly with 5/0 vicryl, the external epithelium of the dissected tract was fulgurated with the diathermy, then a second layer of local soft tissue was secured over ...

  12. Si Tight-Binding Parameters from Genetic Algorithm Fitting

    Science.gov (United States)

    Klimeck, G.; Bowen, R.; Boykin, T.; Salazar-Lazaro, C.; Cwik, T.; Stoica, A.

    1999-01-01

    Quantum mechanical simulations of carrier transport in Si require an accurate model of the complicated Si bandstructure. Tight-binding models are an attractive method of choice since they bear the full electronic structure symmetry in them and they can discretize a realistic device on an atomic scale.

  13. Sit-Tight Syndrome and Tenure Elongation in African Politics ...

    African Journals Online (AJOL)

    The post-independence politics of African countries has been dominated by the phenomenon of sit-tight African heads of state and government who had acceeded to office by election or coup d'etat. This paper examines this recurring problem in post-independence African politics by examining its general and specific ...

  14. Natural Gas Monthly, October 1993

    Energy Technology Data Exchange (ETDEWEB)

    1993-11-10

    The (NGM) Natural Gas Monthly highlights activities, events, and analyses of interest to public and private sector organizations associated with the natural gas industry. Volume and price data are presented each month for natural gas production, distribution, consumption, and interstate pipeline activities. Producer-related activities and underground storage data are also reported. From time to time, the NGM features articles designed to assist readers in using and interpreting natural gas information. This month`s feature articles are: US Production of Natural Gas from Tight Reservoirs: and Expanding Rule of Underground Storage.

  15. Unconventional Tight Reservoirs Characterization with Nuclear Magnetic Resonance

    Science.gov (United States)

    Santiago, C. J. S.; Solatpour, R.; Kantzas, A.

    2017-12-01

    The increase in tight reservoir exploitation projects causes producing many papers each year on new, modern, and modified methods and techniques on estimating characteristics of these reservoirs. The most ambiguous of all basic reservoir property estimations deals with permeability. One of the logging methods that is advertised to predict permeability but is always met by skepticism is Nuclear Magnetic Resonance (NMR). The ability of NMR to differentiate between bound and movable fluids and providing porosity increased the capability of NMR as a permeability prediction technique. This leads to a multitude of publications and the motivation of a review paper on this subject by Babadagli et al. (2002). The first part of this presentation is dedicated to an extensive review of the existing correlation models for NMR based estimates of tight reservoir permeability to update this topic. On the second part, the collected literature information is used to analyze new experimental data. The data are collected from tight reservoirs from Canada, the Middle East, and China. A case study is created to apply NMR measurement in the prediction of reservoir characterization parameters such as porosity, permeability, cut-offs, irreducible saturations etc. Moreover, permeability correlations are utilized to predict permeability. NMR experiments were conducted on water saturated cores. NMR T2 relaxation times were measured. NMR porosity, the geometric mean relaxation time (T2gm), Irreducible Bulk Volume (BVI), and Movable Bulk Volume (BVM) were calculated. The correlation coefficients were computed based on multiple regression analysis. Results are cross plots of NMR permeability versus the independently measured Klinkenberg corrected permeability. More complicated equations are discussed. Error analysis of models is presented and compared. This presentation is beneficial in understanding existing tight reservoir permeability models. The results can be used as a guide for choosing

  16. Numerical Investigation of Cross Flow Phenomena in a Tight-Lattice Rod Bundle Using Advanced Interface Tracking Method

    Science.gov (United States)

    Zhang, Weizhong; Yoshida, Hiroyuki; Ose, Yasuo; Ohnuki, Akira; Akimoto, Hajime; Hotta, Akitoshi; Fujimura, Ken

    In relation to the design of an innovative FLexible-fuel-cycle Water Reactor (FLWR), investigation of thermal-hydraulic performance in tight-lattice rod bundles of the FLWR is being carried out at Japan Atomic Energy Agency (JAEA). The FLWR core adopts a tight triangular lattice arrangement with about 1 mm gap clearance between adjacent fuel rods. In view of importance of accurate prediction of cross flow between subchannels in the evaluation of the boiling transition (BT) in the FLWR core, this study presents a statistical evaluation of numerical simulation results obtained by a detailed two-phase flow simulation code, TPFIT, which employs an advanced interface tracking method. In order to clarify mechanisms of cross flow in such tight lattice rod bundles, the TPFIT is applied to simulate water-steam two-phase flow in two modeled subchannels. Attention is focused on instantaneous fluctuation characteristics of cross flow. With the calculation of correlation coefficients between differential pressure and gas/liquid mixing coefficients, time scales of cross flow are evaluated, and effects of mixing section length, flow pattern and gap spacing on correlation coefficients are investigated. Differences in mechanism between gas and liquid cross flows are pointed out.

  17. Preconditioning Filter Bank Decomposition Using Structured Normalized Tight Frames

    Directory of Open Access Journals (Sweden)

    Martin Ehler

    2015-01-01

    Full Text Available We turn a given filter bank into a filtering scheme that provides perfect reconstruction, synthesis is the adjoint of the analysis part (so-called unitary filter banks, all filters have equal norm, and the essential features of the original filter bank are preserved. Unitary filter banks providing perfect reconstruction are induced by tight generalized frames, which enable signal decomposition using a set of linear operators. If, in addition, frame elements have equal norm, then the signal energy is spread through the various filter bank channels in some uniform fashion, which is often more suitable for further signal processing. We start with a given generalized frame whose elements allow for fast matrix vector multiplication, as, for instance, convolution operators, and compute a normalized tight frame, for which signal analysis and synthesis still preserve those fast algorithmic schemes.

  18. Maximally Localized Radial Profiles for Tight Steerable Wavelet Frames.

    Science.gov (United States)

    Pad, Pedram; Uhlmann, Virginie; Unser, Michael

    2016-05-01

    A crucial component of steerable wavelets is the radial profile of the generating function in the frequency domain. In this paper, we present an infinite-dimensional optimization scheme that helps us find the optimal profile for a given criterion over the space of tight frames. We consider two classes of criteria that measure the localization of the wavelet. The first class specifies the spatial localization of the wavelet profile, and the second that of the resulting wavelet coefficients. From these metrics and the proposed algorithm, we construct tight wavelet frames that are optimally localized and provide their analytical expression. In particular, one of the considered criterion helps us finding back the popular Simoncelli wavelet profile. Finally, the investigation of local orientation estimation, image reconstruction from detected contours in the wavelet domain, and denoising indicate that optimizing wavelet localization improves the performance of steerable wavelets, since our new wavelets outperform the traditional ones.

  19. Daya Bay Antineutrino Detector Gas System

    OpenAIRE

    Band, H. R.; Cherwinka, J. J.; Chu, M-C.; Heeger, K. M.; Kwok, M. W.; Shih, K.; Wise, T.; Xiao, Q.

    2012-01-01

    The Daya Bay Antineutrino Detector gas system is designed to protect the liquid scintillator targets of the antineutrino detectors against degradation and contamination from exposure to ambient laboratory air. The gas system is also used to monitor the leak tightness of the antineutrino detector assembly. The cover gas system constantly flushes the gas volumes above the liquid scintillator with dry nitrogen to minimize oxidation of the scintillator over the five year lifetime of the experimen...

  20. Localization of tight closure in two-dimensional rings

    Indian Academy of Sciences (India)

    R. Narasimhan (Krishtel eMaging) 1461 1996 Oct 15 13:05:22

    I∗Rm = (IRm)∗ . The following extend this fact. Lemma 2.2. Let I be an ideal of R. Let p be a maximal ideal of R which is minimal over I. Then I. ∗Rp = (IRp)∗ . In particular, if R/I is an Artinian ring, then tight closure commutes with localization for I. Proof. SinceIRp ispRp-primary, it follows thatIRp contains some power ofpRp.

  1. Vacuum-tight joints and seals usina glass ceramics

    International Nuclear Information System (INIS)

    Domanskaya, A.V.; Zagajnyj, V.K.; Pevzner, B.Z.; Peregud, V.I.

    1982-01-01

    Results of studying for a possible utilization of new types of vacuum-tight designs made using glass ceramics are given. Constructional features of diffrent joints are considered and their vacuum and electric characteristics are given. Optimum range of application of these designs in electrophysical equipment is shown. Under operating conditions these designs provide a 1.5x10 - 5 Pa pressure and withstand a 2 kV voltage at a 400 deg C temperature

  2. Tight Network Topology Dependent Bounds on Rounds of Communication

    OpenAIRE

    Chattopadhyay, Arkadev; Langberg, Michael; Li, Shi; Rudra, Atri

    2016-01-01

    We prove tight network topology dependent bounds on the round complexity of computing well studied $k$-party functions such as set disjointness and element distinctness. Unlike the usual case in the CONGEST model in distributed computing, we fix the function and then vary the underlying network topology. This complements the recent such results on total communication that have received some attention. We also present some applications to distributed graph computation problems. Our main contri...

  3. Quantum tight-binding chains with dissipative coupling

    International Nuclear Information System (INIS)

    Mogilevtsev, D; Slepyan, G Ya; Garusov, E; Kilin, S Ya; Korolkova, N

    2015-01-01

    We present a one-dimensional tight-binding chain of two-level systems coupled only through common dissipative Markovian reservoirs. This quantum chain can demonstrate anomalous thermodynamic behavior contradicting Fourier law. Population dynamics of individual systems of the chain is polynomial with the order determined by the initial state of the chain. The chain can simulate classically hard problems, such as multi-dimensional random walks. (paper)

  4. Tight Left Upper Lobe Collapse from Lung Cancer

    Science.gov (United States)

    2010-07-01

    tight pulmonary lobar collapse. Summary of Imaging Findings An 83-year-old male smoker with history of COPD on 2L home oxygen presented to...appendage.” Recent prior spirometry was noted to have “decreased FEV1 and FEV1/FVC ratio with hyperbolic expiratory limb of the flow-volume loop...when assessing lobar collapse in adults and smokers . 1 In young adults (less than age 40), endobronchial carcinoid tumor is common. In post

  5. Tightly localized stationary pulses in a multilevel atomic system

    International Nuclear Information System (INIS)

    Liu, Xiong-Jun; Oh, C. H.; Liu, Xin; Liu, Zheng-Xin; Kwek, L. C.

    2007-01-01

    We show that the pulse matching phenomenon can be obtained in the general multilevel system with electromagnetically induced transparency. For this we find a different way to create tightly localized stationary pulses by using counterpropagating pump fields. The present process is a spatial compression of excitation so that it allows us to shape and further intensify the localized stationary pulses, without using standing waves of pump fields or spatially modulated pump fields

  6. Development of a compositional model fully coupled with geomechanics and its application to tight oil reservoir simulation

    Science.gov (United States)

    Xiong, Yi

    solutions and results of a commercial simulator before conducting numerical studies. The numerical studies demonstrate the effect of capillary pressure on VLE, and further on production performance. The significant effect of capillary pressure on VLE leads to the suppression of bubble-point pressure and more light components dissolved in the oil phase. Consequently it is observed that there is smaller gas saturation, larger mole fractions of light components, and faster pressure decreasing at reservoir conditions; meanwhile less gas and more oil are produced at surface. The substantial decrease in reservoir pore pressure results in a large increase of effective stress, which induces the changes of rock properties and influences the production performance. The stress-induced degradation of permeability undermines the production performance, and the geomechanical effect on the permeability of natural fractures is mainly responsible for the undermined production performance. The reduction of pore size due to the geomechanical effect could increase the capillary pressure, which enlarges the influence of capillarity on VLE and further suppresses bubble-point pressure. On the other hand, the effect of capillary pressure on VLE influences the fluid flow and therefore influences the effective stress through the flow-stress coupling process. Thus the interaction between pore confinement and rock compaction can be modeled with MSFLOW_COM, and illustrated through numerical studies. This research provides a three-dimensional numerical tool for accurately modeling porous and fractured tight oil reservoirs. The developed simulator is able to assist scientists and engineers to study and understand the complex multiphase, multi-component fluid flow behaviors in tight oil reservoirs.

  7. Tight junction regulates epidermal calcium ion gradient and differentiation

    International Nuclear Information System (INIS)

    Kurasawa, Masumi; Maeda, Tetsuo; Oba, Ai; Yamamoto, Takuya; Sasaki, Hiroyuki

    2011-01-01

    Research highlights: → We disrupted epidermal tight junction barrier in reconstructed epidermis. → It altered Ca 2+ distribution and consequentially differentiation state as well. → Tight junction should affect epidermal homeostasis by maintaining Ca 2+ gradient. -- Abstract: It is well known that calcium ions (Ca 2+ ) induce keratinocyte differentiation. Ca 2+ distributes to form a vertical gradient that peaks at the stratum granulosum. It is thought that the stratum corneum (SC) forms the Ca 2+ gradient since it is considered the only permeability barrier in the skin. However, the epidermal tight junction (TJ) in the granulosum has recently been suggested to restrict molecular movement to assist the SC as a secondary barrier. The objective of this study was to clarify the contribution of the TJ to Ca 2+ gradient and epidermal differentiation in reconstructed human epidermis. When the epidermal TJ barrier was disrupted by sodium caprate treatment, Ca 2+ flux increased and the gradient changed in ion-capture cytochemistry images. Alterations of ultrastructures and proliferation/differentiation markers revealed that both hyperproliferation and precocious differentiation occurred regionally in the epidermis. These results suggest that the TJ plays a crucial role in maintaining epidermal homeostasis by controlling the Ca 2+ gradient.

  8. Radiation-tight coupling arrangement for a machining laser

    International Nuclear Information System (INIS)

    Geffroy, J.; Glachet, C.; Moulin, M.; Noel, J. P.

    1985-01-01

    A radiation-tight coupling arrangement for coupling a machining laser to a hot cell containing radioactive material, comprising a cell flange integrally formed on the confinement wall which defines a cell opening, a cell door formed to interlock tightly with the cell flange, thereby closing the cell opening, an elongated container movably arranged in the sleeve and having a container flange defining a container opening and connected by a sealing bellows, a container door formed to interlock tightly with the container flange and to interlock with the cell door when the container flange interlocks with the cell flange, and a machining line translationally arranged in the container. When the container is in a retracted position, a radiation blocking drum intervenes between the cell opening and the container opening. The radiation blocking drum is rotated to allow the container to translate toward the cell. As a result of rotation of the container, the container flange interlocks with the cell flange and the container door interlocks with the cell door. The container door and cell door are then removed in tandem, allowing the machine head of the machining line to be inserted into the hot cell. The laser beam passes through the machine head and impinges on the radioactive material to be cut

  9. Polynomial fitting of tight-binding method in carbon

    Science.gov (United States)

    Haa, Wai Kang; Yeak, Su Hoe

    2017-04-01

    Carbon is very unique in among the elements and its ability to form strong chemical bonds with a variety number such as two carbons (graphene) and four carbons (diamond). This combination of strong bonds with tight mass and high melting point makes them technologically and scientifically important in nanoscience development. Tight-binding model (TB) is one of the semi-empirical approximations used in quantum mechanical world which is restricted to the Linear Combinations of Localized Atomic Orbitals (LCAO). Currently, there are many approaches in tight-binding calculation. In this paper, we have reproduced a polynomial scaling function by fitting to the TB model. The model is then applied into carbon molecules and obtained the energy bands of the system. The elements of the overlap Hamiltonian matrix in the model will be depending on the parameter of the polynomials. Our purpose is to find out a set of parameters in the polynomial which were commonly fit to an independently calculated band structure. We used minimization approach to calculate the polynomial coefficients which involves differentiation of eigenvalues in the eigensystem. The algorithm of fitting the parameters is carried out in FORTRAN.

  10. Tests of a tight scintillator assembly for a sheath failure detector

    International Nuclear Information System (INIS)

    Vasnier, F.

    1968-01-01

    This report first recalls that fission product detectors operating under CO 2 pressure at room temperature are equipped with plastic scintillators which are directly in contact with CO 2 to perform a measurement of the β radiation of collected Rb and Cs atoms, and that defects such as cracks and dimensional variations appeared in these scintillators. As some works showed the influence of CO 2 absorption by plastic scintillators, and the negative influence of oil vapours within the gas on these defects, a tight protection has been proposed for the scintillators by means a thin metal sheath, in order to reduce the energy loss of the β radiation. The author reports tests performed on a prototype to measure the sensitivity decrease due to the β absorption by the stainless steel sheath with respect to a normal scintillator assembly, as well as the change of the signal-to-noise ratio [fr

  11. The Role of the Rock on Hydraulic Fracturing of Tight Shales

    Science.gov (United States)

    Suarez-Rivera, R.; Green, S.; Stanchits, S.; Yang, Y.

    2011-12-01

    Successful economic production of oil and gas from nano-darcy-range permeability, tight shale reservoirs, is achieved via massive hydraulic fracturing. This is so despite their limited hydrocarbon in place, on per unit rock volume basis. As a reference, consider a typical average porosity of 6% and an average hydrocarbon saturation of 50% to 75%. The importance of tight shales results from their large areal extent and vertical thickness. For example, the areal extent of the Anwar field in Saudi Arabia of 3230 square miles (and 300 ft thick), while the Marcellus shale alone is over 100,000 square miles (and 70 to 150 ft thick). The low permeability of the rock matrix, the predominantly mineralized rock fabric, and the high capillary forces to both brines and hydrocarbons, restrict the mobility of pore fluids in these reservoirs. Thus, one anticipates that fluids do not move very far within tight shales. Successful production, therefore results from maximizing the surface area of contact with the reservoir by massive hydraulic fracturing from horizontal bore holes. This was the conceptual breakthrough of the previous decade and the one that triggered the emergence of gas shales, and recently oily shales, as important economic sources of energy. It is now understood that the process can be made substantially more efficient, more sustainable, and more cost effective by understanding the rock. This will be the breakthrough of this decade. Microseismic monitoring, mass balance calculations, and laboratory experiments of hydraulic fracturing on tight shales indicate the development of fracture complexity and fracture propagation that can not be explained in detail in this layered heterogeneous media. It is now clear that in tight shales the large-scale formation fabric is responsible for fracture complexity. For example, the presence and pervasiveness of mineralized fractures, bed interfaces, lithologic contacts, and other types of discontinuities, and their orientation

  12. How unconventional gas prospers without tax incentives

    International Nuclear Information System (INIS)

    Kuuskraa, V.A.; Stevens, S.H.

    1995-01-01

    It was widely believed that the development of unconventional natural gas (coalbed methane, gas shales, and tight gas) would die once US Sec. 29 credits stopped. Quieter voices countered, and hoped, that technology advances would keep these large but difficult to produce gas resources alive and maybe even healthy. Sec. 29 tax credits for new unconventional gas development stopped at the end of 1992. Now, nearly three years later, who was right and what has happened? There is no doubt that Sec. 29 tax credits stimulated the development of coalbed methane, gas shales, and tight gas. What is less known is that the tax credits helped spawn and push into use an entire new set of exploration, completion, and production technologies founded on improved understanding of unconventional gas reservoirs. As set forth below, while the incentives inherent in Sec. 29 provided the spark, it has been the base of science and technology that has maintained the vitality of these gas sources. The paper discusses the current status; resource development; technology; unusual production, proven reserves, and well completions if coalbed methane, gas shales, and tight gas; and international aspects

  13. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    International Nuclear Information System (INIS)

    Li, Zhao; Jin, Zhu-Qiu

    2012-01-01

    Highlights: ► Cardiac tight junctions are present between coronary endothelial cells. ► Ischemic preconditioning preserves the structural and functional integrity of tight junctions. ► Myocardial edema is prevented in hearts subjected to ischemic preconditioning. ► Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood–heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs–Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC enhanced the translocation of ZO-2 from cytosol to cytoskeleton. In conclusion, TJs occur in

  14. Containment leak-tightness enhancement at VVER 440 NPPs

    International Nuclear Information System (INIS)

    Prandorfy, M.

    2001-01-01

    The hermetic compartments of VVER 440 NPPs fulfil the function of the containment used at NPPs all over the word. The purpose of the containment is to protect the NPP personal against radioactive impact as well as to prevent radioactive leakage to the environment during a lost of coolant accident. Leak-tightness enhancement in NPPs with VVER 440/213 and VVER 440/230 reactors is an important safety issue. New procedures, measures and methods were adopted at NPPs in Mochovce, J. Bohunice, Dukovany and Paks for leak identification and sealing works performed by VUEZ Levice. (authors)

  15. Tight-binding model for borophene and borophane

    Science.gov (United States)

    Nakhaee, M.; Ketabi, S. A.; Peeters, F. M.

    2018-03-01

    Starting from the simplified linear combination of atomic orbitals method in combination with first-principles calculations, we construct a tight-binding (TB) model in the two-centre approximation for borophene and hydrogenated borophene (borophane). The Slater and Koster approach is applied to calculate the TB Hamiltonian of these systems. We obtain expressions for the Hamiltonian and overlap matrix elements between different orbitals for the different atoms and present the SK coefficients in a nonorthogonal basis set. An anisotropic Dirac cone is found in the band structure of borophane. We derive a Dirac low-energy Hamiltonian and compare the Fermi velocities with that of graphene.

  16. Tight Bound on Randomness for Violating the CHSH Inequality

    OpenAIRE

    Teng, Yifeng; Yang, Shenghao; Wang, Siwei; Zhao, Mingfei

    2015-01-01

    Free will (or randomness) has been studied to achieve loophole-free Bell's inequality test and to provide device-independent quantum key distribution security proofs. The required randomness such that a local hidden variable model (LHVM) can violate the Clauser-Horne-Shimony-Holt (CHSH) inequality has been studied, but a tight bound has not been proved for a practical case that i) the device settings of the two parties in the Bell test are independent; and ii) the device settings of each part...

  17. Tight glycemic control in the ICU - is the earth flat?

    Science.gov (United States)

    Steil, Garry M; Agus, Michael S D

    2014-06-27

    Tight glycemic control in the ICU has been shown to reduce mortality in some but not all prospective randomized control trials. Confounding the interpretation of these studies are differences in how the control was achieved and underlying incidence of hypoglycemia, which can be expected to be affected by the introduction of continuous glucose monitoring (CGM). In this issue of Critical Care, a consensus panel provides a list of the research priorities they believe are needed for CGM to become routine practice in the ICU. We reflect on these recommendations and consider the implications for using CGM today.

  18. Air tightness measurements in older Danish single-family houses

    DEFF Research Database (Denmark)

    Mortensen, Lone Hedegaard; Bergsøe, Niels Christian

    2017-01-01

    presents the results of measurements in 16 single-family houses built between 1880 and 2007. The air tightness of the building envelope was measured according to EN ISO 9972 using the blower-door technique. The results are compared with measurement results of the average air-change rate in the same houses....... In addition, leaks are observed around older windows and doors and in connection with wooden ceilings and attic hatches. The findings should be taken into account when renovating older single-family houses....

  19. Containment leak-tightness enhancement at VVER 440 NPPs

    International Nuclear Information System (INIS)

    Prandorfy, M.

    2000-01-01

    The hermetic compartments of WWER 440 NPPs fulfil the function of the containment used at NPPs all over the world. The purpose of the containment is to protect the NPP personnel against radioactive impact as well as to prevent radioactive leakage to the. environ ent during a lost of coolant accident. Leak-tightness enhancement in NPPs with WWER 440/213 and WWER 440/230 reactors is an important safety issue. New procedures, measures and methods were adopted at NPPs in Mochovce, Jaslovske Bohunice, Dukovany and PAKS for leak identification and sealing works performed by VUEZ Levice. (authors)

  20. Comparative testing of women's tights, which are realized in the Ukrainian market

    OpenAIRE

    Мартосенко, Марина Григорьевна; Браилко, Анна Сергеевна

    2015-01-01

    Assortment of women's tights represented on the Ukrainian market is diverse: medical and corrective tights, classic thin and warm, simple and exclusive, ornamental and sports, for pregnant women and moisturizing effect. The size, density, pattern, material composition, visual appearance, matching fashion trends, colors, pricing policy – all these are criteria for the selection of women's tights.With such huge and diverse range of women's tights in the Ukrainian market, the problem of quality ...

  1. Gas and Gas Pains

    Science.gov (United States)

    ... to produce gas. Often, relatively simple changes in eating habits can lessen bothersome gas. Certain digestive system disorders, ... such as soda and beer, increase stomach gas. Eating habits, such as eating too quickly, drinking through a ...

  2. Fission gas retention in irradiated metallic fuel

    International Nuclear Information System (INIS)

    Fenske, G.R.; Gruber, E.E.; Kramer, J.M.

    1987-01-01

    Theoretical calculations and experimental measurements of the quantity of retained fission gas in irradiated metallic fuel (U-5Fs) are presented. The calculations utilize the Booth method to model the steady-state release of gases from fuel grains and a simplified grain-boundary gas model to predict the gas release from intergranular regions. The quantity of gas retained in as-irradiated fuel was determined by collecting the gases released from short segments of EBR-II driver fuel that were melted in a gas-tight furnace. Comparison of the calculations to the measurements shows quantitative agreement with both the magnitude and the axial variation of the retained gas content

  3. Maintaining leak tightness capability of Caorso BWR containment

    International Nuclear Information System (INIS)

    Barsanti, P.; Di Palo, L.; Grimaldi, G.

    1988-01-01

    In 1987 the local leak rate test (LLRT) results of the primary containment were revised, with the following main goals: to highlight recurring problems, leading to lack of leak tightness of the primary containment; to individuate the pertinent degradation mechanisms; to assess the corrective actions already implemented and to plan further improvements, if necessary; and to optimize the preventive maintenance program on the containment, particularly the inspection frequency. All LLRTs in the past operating period, both before (as found) and after (as left) maintenance were analyzed, in terms of leakage rate and equivalent area of leak, for each penetration. Corrective actions already implemented included replacement of some valves with better quality type one, passivation of the carbon steel pipes and improvement of the pertinent surveillance procedures. Long term corrective actions, now under consideration, will include the following: more extensive passivation of pipes, carrying humid air, so that oxidation could be drastically reduced; better chemistry control in fluid systems; extensive replacement of the butterfly valves presently used; implementation of the LLRT practice, such to quantitatively measure the leakage rate, also in presence of large leak; and reduction of the time interval between periodical tests, on the basis of the results of the previous ones. Following these guidelines, future overall leakage tests would be performed in as found condition, aimed to verify the effectiveness of the entire maintenance and testing program of the primary containment and of its capability to maintain leak tightness during the time between two subsequent tests

  4. Adaptive wavelet tight frame construction for accelerating MRI reconstruction

    Directory of Open Access Journals (Sweden)

    Genjiao Zhou

    2017-09-01

    Full Text Available The sparsity regularization approach, which assumes that the image of interest is likely to have sparse representation in some transform domain, has been an active research area in image processing and medical image reconstruction. Although various sparsifying transforms have been used in medical image reconstruction such as wavelet, contourlet, and total variation (TV etc., the efficiency of these transforms typically rely on the special structure of the underlying image. A better way to address this issue is to develop an overcomplete dictionary from the input data in order to get a better sparsifying transform for the underlying image. However, the general overcomplete dictionaries do not satisfy the so-called perfect reconstruction property which ensures that the given signal can be perfectly represented by its canonical coefficients in a manner similar to orthonormal bases, resulting in time consuming in the iterative image reconstruction. This work is to develop an adaptive wavelet tight frame method for magnetic resonance image reconstruction. The proposed scheme incorporates the adaptive wavelet tight frame approach into the magnetic resonance image reconstruction by solving a l0-regularized minimization problem. Numerical results show that the proposed approach provides significant time savings as compared to the over-complete dictionary based methods with comparable performance in terms of both peak signal-to-noise ratio and subjective visual quality.

  5. Tight-binding tunneling amplitude of an optical lattice

    Science.gov (United States)

    Arzamasovs, Maksims; Liu, Bo

    2017-11-01

    The particle in a periodic potential is an important topic in an undergraduate quantum mechanics curriculum and a stepping stone on the way to more advanced topics, such as courses on interacting electrons in crystalline solids, and graduate-level research in solid-state and condensed matter physics. The interacting many-body phenomena are usually described in terms of the second quantized lattice Hamiltonians which treat single-particle physics on the level of tight-binding approximation and add interactions on top of it. The aim of this paper is to show how the tight-binding tunneling amplitude can be related to the strength of the periodic potential for the case of a cosine potential used in the burgeoning field of ultracold atoms. We show how to approach the problem of computing the tunneling amplitude of a deep lattice using the JWKB (Jeffreys-Wentzel-Kramers-Brillouin, also known as semiclassical) approximation. We also point out that care should be taken when applying the method of the linear combination of atomic orbitals (LCAO) in an optical lattice context. A summary of the exact solution in terms of Mathieu functions is also given.

  6. Tight-binding tunneling amplitude of an optical lattice

    International Nuclear Information System (INIS)

    Arzamasovs, Maksims; Liu, Bo

    2017-01-01

    The particle in a periodic potential is an important topic in an undergraduate quantum mechanics curriculum and a stepping stone on the way to more advanced topics, such as courses on interacting electrons in crystalline solids, and graduate-level research in solid-state and condensed matter physics. The interacting many-body phenomena are usually described in terms of the second quantized lattice Hamiltonians which treat single-particle physics on the level of tight-binding approximation and add interactions on top of it. The aim of this paper is to show how the tight-binding tunneling amplitude can be related to the strength of the periodic potential for the case of a cosine potential used in the burgeoning field of ultracold atoms. We show how to approach the problem of computing the tunneling amplitude of a deep lattice using the JWKB (Jeffreys–Wentzel–Kramers–Brillouin, also known as semiclassical) approximation. We also point out that care should be taken when applying the method of the linear combination of atomic orbitals (LCAO) in an optical lattice context. A summary of the exact solution in terms of Mathieu functions is also given. (paper)

  7. MANAGING TIGHT BINDING RECEPTORS FOR NEW SPEARATIONS TECHNOLOGIES

    Energy Technology Data Exchange (ETDEWEB)

    DARYLE H BUSCH RICHARD S GIVENS

    2004-12-10

    Much of the earth's pollution involves compounds of the metallic elements, including actinides, strontium, cesium, technetium, and RCRA metals. Metal ions bind to molecules called ligands, which are the molecular tools that can manipulate the metal ions under most conditions. This DOE-EMSP sponsored program strives (1) to provide the foundations for using the most powerful ligands in transformational separations technologies and (2) to produce seminal examples of their applications to separations appropriate to the DOE EM mission. These ultra tight-binding ligands can capture metal ions in the most competitive of circumstances (from mineralized sites, lesser ligands, and even extremely dilute solutions), but they react so slowly that they are useless in traditional separations methodologies. Two attacks on this problem are underway. The first accommodates to the challenging molecular lethargy by developing a seminal slow separations methodology termed the soil poultice. The second designs ligands that are only tight-binding while wrapped around the targeted metal ion, but can be put in place by switch-binding and removed by switch-release. We envision a kind of molecular switching process to accelerate the union between metal ion and tight-binding ligand. Molecular switching processes are suggested for overcoming the slow natural equilibration rate with which ultra tight-binding ligands combine with metal ions. Ligands that bind relatively weakly combine with metal ions rapidly, so the trick is to convert a ligand from a weak, rapidly binding species to a powerful, slow releasing ligand--during the binding of the ligand to the metal ion. Such switch-binding ligands must react with themselves, and the reaction must take place under the influence of the metal ion. For example, our generation 1 ligands showed that a well-designed linear ligand with ends that readily combine, forms a cyclic molecule when it wraps around a metal ion. Our generation 2 ligands are

  8. Tight Fits for Americas Next Moon Rocket, Ares V

    Science.gov (United States)

    Jaap, John; Fisher, Wyatt; Richardson, Lea

    2010-01-01

    America has begun the development of a new heavy lift rocket which will enable humans to return to the moon and reach even farther destinations. Five decades ago, the National Aeronautics and Space Administration designed a system (called Saturn/Apollo) to carry men to the moon and back; the rocket which boosted them to the moon was the Saturn V. Saturn V was huge relative to contemporary rockets and is still the largest rocket ever launched. The new moon rocket is called Ares V. It will insert 40% more payload into low earth orbit than Saturn V; and after docking with the crew spacecraft, it will insert 50% more payload onto the translunar trajectory than Saturn V. The current design of Ares V calls for two liquid-fueled stages and 2 "strap-on" solid rockets. The solid rockets are extended-length versions of the solid rockets used on the Shuttle. The diameter of the liquid stages is at least as large as the first stage of the Saturn V; the height of the lower liquid stage (called the core stage) is longer than the external tank of the Shuttle. Huge rockets require huge infrastructure and, during the Saturn/Apollo era, America invested significantly in manufacturing, assembly and launch facilities which are still in use today. Since the Saturn/Apollo era, America has invested in additional infrastructure for the Shuttle program. Ares V must utilize this existing infrastructure, with reasonable modifications. Building a rocket with 50% more capability in the same buildings, testing it in the same test stands, shipping on the same canals under the same bridges, assembling it in the same building, rolling it to the pad on the same crawler, and launching it from the same launch pad is an engineering and logistics challenge which goes hand-in-hand with designing the structure, tanks, turbines, engines, software, etc. necessary to carry such a large payload to earth orbit and to the moon. This paper quantitatively discusses the significant "tight fits" that are

  9. Enforcing dust mass conservation in 3D simulations of tightly-coupled grains with the PHANTOM SPH code

    Science.gov (United States)

    Ballabio, G.; Dipierro, G.; Veronesi, B.; Lodato, G.; Hutchison, M.; Laibe, G.; Price, D. J.

    2018-03-01

    We describe a new implementation of the one-fluid method in the SPH code PHANTOM to simulate the dynamics of dust grains in gas protoplanetary discs. We revise and extend previously developed algorithms by computing the evolution of a new fluid quantity that produces a more accurate and numerically controlled evolution of the dust dynamics. Moreover, by limiting the stopping time of uncoupled grains that violate the assumptions of the terminal velocity approximation, we avoid fatal numerical errors in mass conservation. We test and validate our new algorithm by running 3D SPH simulations of a large range of disc models with tightly- and marginally-coupled grains.

  10. Multiple regions of Crumbs3 are required for tight junction formation in MCF10A cells.

    Science.gov (United States)

    Fogg, Vanessa C; Liu, Chia-Jen; Margolis, Ben

    2005-07-01

    The formation and maintenance of tight junctions is essential for the development of epithelial cell polarity. Recently, a number of conserved polarity-regulating proteins have been shown to localize to epithelial tight junctions, and to play a role in the regulation of tight junction formation. The Crumbs3/PALS1/PATJ protein complex localizes at epithelial tight junctions and interacts with the polarity-regulating protein complex of Par6/Par3/aPKC. Overexpression of Crumbs3 in MDCKII cells leads to a delay in tight junction formation in these cells, suggesting a role in the regulation of tight junction development. Here we report new evidence that Crumbs3 indeed plays an essential role in tight junction formation. Mammary MCF10A cells express little endogenous Crumbs3 and fail to form tight junctions when grown under standard tissue culture conditions. The staining pattern of ZO-1, a tight junction marker, is fragmented, and other tight junction markers show either fragmented junctional expression or diffuse cytoplasmic staining. Expression of exogenous Crumbs3 induces the formation of tight junction structures marked by smooth, continuous ZO-1 staining at apical cell-cell junctions. A number of other tight junction markers, including claudin-1 and occludin, are also recruited to these junctions. Analysis by transmission electron microscopy and measurements of the transepithelial electrical resistance confirm that these structures are functional tight junctions. Mutations in either the Crumbs3 PDZ binding motif or the putative FERM binding motif lead to defects in the ability of Crumbs3 to promote tight junction development. Our results suggest that Crumbs3 plays an important role in epithelial tight junction formation, and also provide the first known functional role for the mammalian Crumbs FERM binding domain.

  11. Integrated seismic study of naturally fractured tight gas reservoirs. Final report, September 1991--January 1995

    Energy Technology Data Exchange (ETDEWEB)

    Mavko, G.; Nur, A.

    1995-01-01

    The approach in this project has been to integrate the principles of rock physics into a quantitative processing and interpretation scheme that exploits, where possible, the broader spectrum of fracture zone signatures: (1) anomalous compressional and shear wave velocity; (2) Q and velocity dispersion; (3) increased velocity anisotropy; (4) amplitude vs. offset (AVO) response, and (5) variations in frequency content. As part of this the authors have attempted to refine some of the theoretical rock physics tools that should be applied in any field study to link the observed seismic signatures to the physical/geologic description of the fractured rock. The project had 3 key elements: (1) rock physics studies of the anisotropic viscoelastic signatures of fractured rocks, (2) acquisition and processing of seismic reflection field data, and (3) interpretation of seismic and well log data. The study site is in a producing field operated by Amoco and Arco at the southern boundary of the Powder River basin in Wyoming. During the winter of 1992--1993 the authors collected about 50 km of 9-component reflection seismic data and obtained existing log data from several wells in the vicinity. The paper gives background information on laboratory studies, seismic field studies of fracture anisotropy, and the problem of upscaling from the laboratory to the field. It discusses fluid effects on seismic anisotropy and a method for predicting stress-induced seismic anisotropy. Then results from the field experiment are presented and discussed: regional geologic framework and site description; seismic data acquisition; shear wave data and validation; and P-wave data analysis. 106 refs., 52 figs.

  12. Numerical investigation and optimization of multiple fractures in tight gas reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Hou, M.Z. [Technische Univ. Clausthal, Clausthal-Zellerfeld (Germany). ITE; Energie-Forschungszentrum Niedersachsen, Goslar (Germany); Zhou, L. [Energie-Forschungszentrum Niedersachsen, Goslar (Germany)

    2013-08-01

    The main objective of the project DGMK-680 in phase 2 was to investigate the influence of fractures on each other in a multi-fracture system including their space optimization by using the numerical program FLAC3D with our own developments, which treats all fractures in one 3D geometric model under 3D stress state with fully hydro-mechanical coupling effect. The case study was conducted on a horizontal wellbore at location A, which was stimulated hydraulically with a total of eight transverse fractures in summer 2009. Transverse multiple fractures were simulated using the modified continuum method. In the simulation all fractures were generated in one single model, comprising 22 different rock layers. Each layer was assumed to be homogeneous with regard to its rock and hydromechanical parameters. Thus the influence of the individual fractures on each other can be investigated. The simulation procedure applied, which is a consecutive execution ofa hydraulic and a mechanical computation, is the same for all fractures. The only differences are the primary in-situ stresses, the initial pore pressure, the injection parameters (location, rate, volume, duration), which lead to different patterns of fracture propagations. But there are still some common points, such as irregular patterns of the fracture front, which represents the heterogeneity of the model. All fractures (1 to 8) have their fracture average half-length between 70 m to 115 m, height between 93 m to 114 m and average width between 18 mm to 31 mm. The percentage difference of fracture height for individual fractures is obviously smaller than that of the fracture half-lengths, because the fracture barriers at bottom and top limit the fracture propagation in z-direction. Incomparison with the analytical simulator (FracPro) most results match well. Simulation of multiple fractures at location A, with the newly developed algorithms, shows that individual transverse multiple fractures at distances between 100 -150 m will certain influence on each other in terms of the stress change, but not pore pressure. Generally, this influence as simulated at this location has a positive effect on the fracture geometry as well, and may lead to a bigger half-length and a smaller width of the fracture. In order to maximize the production rate in this specific site, transverse multiple fractures with an optimal fracture distance of ca. 57 m should be implemented. This optimal fracture spacing is derived from the counter of 5 direction change of the primary maximum horizontal stress, to ensure that only transverse fractures are generated in this location. However, the influence on longitudinal multiple fractures is very obvious, as observed from the numerical simulations of longitudinal multiple fractures at U2. Under the circumstances, it is recommended that the boreholes should not be drilled exactly in the direction of maximal horizontal stress ({+-}15 ), in order to avoid the overlapping of fractures. (orig.)

  13. Design considerations for teleoperation systems operating in gas-tight argon cells

    Directory of Open Access Journals (Sweden)

    Seungnam Yu

    2017-12-01

    Full Text Available In the nuclear industry, mechanical engineers spend a significant portion of their time designing equipment such as manipulators, bogies, mechanical grippers, and so on. Some customized designs can be considered as standard mechanical equipment in this area, although it is not unusual to find that an existing design cannot simply be copied from one project to another. Varied performance requirements can dictate that redesign, often quite extensive redesign, is required. However, if something similar has been done before, engineers could use that as a starting point for the new project. In this regard, this study presents several guidelines inspired by previous design knowledge for similar development cases. Moreover, this study presents more detailed suggestions such as design guidelines for an argon-based hot cell atmosphere and design experience for a large-scale practical hot cell facility. Design considerations and case studies dealt with in this study are dedicated to teleoperation manipulators that are used at a large-scale argon cell facility for pyroprocess integrated inactive demonstration (PRIDE, at the Korea Atomic Energy Research Institute. In particular, for case studies to support the suggested recommendations, a fabricated telemanipulator system for PRIDE is introduced, and several kinds of experimental results associated with it are presented.

  14. Experimental evaluation on the damages of different drilling modes to tight sandstone reservoirs

    Directory of Open Access Journals (Sweden)

    Gao Li

    2017-07-01

    Full Text Available The damages of different drilling modes to reservoirs are different in types and degrees. In this paper, the geologic characteristics and types of such damages were analyzed. Then, based on the relationship between reservoir pressure and bottom hole flowing pressure corresponding to different drilling modes, the experimental procedures on reservoir damages in three drilling modes (e.g. gas drilling, liquid-based underbalanced drilling and overbalanced drilling were designed. Finally, damage simulation experiments were conducted on the tight sandstone reservoir cores of the Jurassic Ahe Fm in the Tarim Basin and Triassic Xujiahe Fm in the central Sichuan Basin. It is shown that the underbalanced drilling is beneficial to reservoir protection because of its less damage on reservoir permeability, but it is, to some extent, sensitive to the stress and the empirical formula of stress sensitivity coefficient is obtained; and that the overbalanced drilling has more reservoir damages due to the invasion of solid and liquid phases. After the water saturation of cores rises to the irreducible water saturation, the decline of gas logging permeability speeds up and the damage degree of water lock increases. It is concluded that the laboratory experiment results of reservoir damage are accordant with the reservoir damage characteristics in actual drilling conditions. Therefore, this method reflects accurately the reservoir damage characteristics and can be used as a new experimental evaluation method on reservoir damage in different drilling modes.

  15. Revenue Risk of U.S. Tight-Oil Firms

    Directory of Open Access Journals (Sweden)

    Luis Mª Abadie

    2016-10-01

    Full Text Available American U.S. crude oil prices have dropped significantly of late down to a low of less than $30 a barrel in early 2016. At the same time price volatility has increased and crude in storage has reached record amounts in the U.S. America. Low oil prices in particular pose quite a challenge for the survival of U.S. America’s tight-oil industry. In this paper we assess the current profitability and future prospects of this industry. The question could be broadly stated as: should producers stop operation immediately or continue in the hope that prices will rise in the medium term? Our assessment is based on a stochastic volatility model with three risk factors, namely the oil spot price, the long-term oil price, and the spot price volatility; we allow for these sources of risk to be correlated and display mean reversion. We then use information from spot and futures West Texas Intermediate (WTI oil prices to estimate this model. Our aim is to show how the development of the oil price in the future may affect the prospective revenues of firms and hence their operation decisions at present. With the numerical estimates of the model’s parameters we can compute the value of an operating tight-oil field over a certain time horizon. Thus, the present value (PV of the prospective revenues up to ten years from now is $37.07/bbl in the base case. Consequently, provided that the cost of producing a barrel of oil is less than $37.07 production from an operating field would make economic sense. Obviously this is just a point estimate. We further perform a Monte Carlo (MC simulation to derive the risk profile of this activity and calculate two standard measures of risk, namely the value at risk (VaR and the expected shortfall (ES (for a given confidence level. In this sense, the PV of the prospective revenues will fall below $22.22/bbl in the worst 5% of the cases; and the average value across these worst scenarios is $19.77/bbl. Last we undertake two

  16. Ischemic preconditioning enhances integrity of coronary endothelial tight junctions

    Energy Technology Data Exchange (ETDEWEB)

    Li, Zhao [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States); Jin, Zhu-Qiu, E-mail: zhu-qiu.jin@sdstate.edu [Department of Pharmaceutical Sciences, College of Pharmacy, South Dakota State University, Brookings, SD 57007 (United States)

    2012-08-31

    Highlights: Black-Right-Pointing-Pointer Cardiac tight junctions are present between coronary endothelial cells. Black-Right-Pointing-Pointer Ischemic preconditioning preserves the structural and functional integrity of tight junctions. Black-Right-Pointing-Pointer Myocardial edema is prevented in hearts subjected to ischemic preconditioning. Black-Right-Pointing-Pointer Ischemic preconditioning enhances translocation of ZO-2 from cytosol to cytoskeleton. -- Abstract: Ischemic preconditioning (IPC) is one of the most effective procedures known to protect hearts against ischemia/reperfusion (IR) injury. Tight junction (TJ) barriers occur between coronary endothelial cells. TJs provide barrier function to maintain the homeostasis of the inner environment of tissues. However, the effect of IPC on the structure and function of cardiac TJs remains unknown. We tested the hypothesis that myocardial IR injury ruptures the structure of TJs and impairs endothelial permeability whereas IPC preserves the structural and functional integrity of TJs in the blood-heart barrier. Langendorff hearts from C57BL/6J mice were prepared and perfused with Krebs-Henseleit buffer. Cardiac function, creatine kinase release, and myocardial edema were measured. Cardiac TJ function was evaluated by measuring Evans blue-conjugated albumin (EBA) content in the extravascular compartment of hearts. Expression and translocation of zonula occludens (ZO)-2 in IR and IPC hearts were detected with Western blot. A subset of hearts was processed for the observation of ultra-structure of cardiac TJs with transmission electron microscopy. There were clear TJs between coronary endothelial cells of mouse hearts. IR caused the collapse of TJs whereas IPC sustained the structure of TJs. IR increased extravascular EBA content in the heart and myocardial edema but decreased the expression of ZO-2 in the cytoskeleton. IPC maintained the structure of TJs. Cardiac EBA content and edema were reduced in IPC hearts. IPC

  17. Trends in drug delivery through tissue barriers containing tight junctions.

    Science.gov (United States)

    Tscheik, Christian; Blasig, Ingolf E; Winkler, Lars

    2013-04-01

    A limitation in the uptake of many drugs is the restricted permeation through tissue barriers. There are two general ways to cross barriers formed by cell layers: by transcytosis or by diffusion through the intercellular space. In the latter, tight junctions (TJs) play the decisive role in the regulation of the barrier permeability. Thus, transient modulation of TJs is a potent strategy to improve drug delivery. There have been extensive studies on surfactant-like absorption enhancers. One of the most effective enhancers found is sodium caprate. However, this modulates TJs in an unspecific fashion. A novel approach would be the specific modulation of TJ-associated marvel proteins and claudins, which are the main structural components of the TJs. Recent studies have identified synthetic peptidomimetics and RNA interference techniques to downregulate the expression of targeted TJ proteins. This review summarizes current progress and discusses the impact on TJs' barrier function.

  18. Bridging the Gap on Tight Separation Brown Dwarf Binaries

    Science.gov (United States)

    Bardalez Gagliuffi, Daniella C.; Burgasser, Adam J.; Gelino, Christopher R.; Melis, Carl; Blake, Cullen

    2015-01-01

    Multiplicity is a key statistic for understanding the formation of very low mass (VLM) stars and brown dwarfs. Currently, the separation distribution of VLM binaries remains poorly constrained at small separations (candidates from a library of 738 spectra from the SpeX Prism Spectral Libraries. We present twelve new binary candidates, confirm two previously reported candidates and rule out other two previously reported candidates. All of our candidates have primary and secondary spectral types between M7-L7 and L8-T8 respectively. We find that blue L dwarfs and subdwarfs are contaminants in our sample and propose a method for segregating these sources. If confirmed by follow-up observations, these systems may potentially add to the growing list of tight separation binaries, giving further insight into brown dwarf formation scenarios.

  19. Approximate equiangular tight frames for compressed sensing and CDMA applications

    Science.gov (United States)

    Tsiligianni, Evaggelia; Kondi, Lisimachos P.; Katsaggelos, Aggelos K.

    2017-12-01

    Performance guarantees for recovery algorithms employed in sparse representations, and compressed sensing highlights the importance of incoherence. Optimal bounds of incoherence are attained by equiangular unit norm tight frames (ETFs). Although ETFs are important in many applications, they do not exist for all dimensions, while their construction has been proven extremely difficult. In this paper, we construct frames that are close to ETFs. According to results from frame and graph theory, the existence of an ETF depends on the existence of its signature matrix, that is, a symmetric matrix with certain structure and spectrum consisting of two distinct eigenvalues. We view the construction of a signature matrix as an inverse eigenvalue problem and propose a method that produces frames of any dimensions that are close to ETFs. Due to the achieved equiangularity property, the so obtained frames can be employed as spreading sequences in synchronous code-division multiple access (s-CDMA) systems, besides compressed sensing.

  20. S0 Tight Loop Studies on ICHIRO 9-Cell Cavities

    Energy Technology Data Exchange (ETDEWEB)

    Furuta, Fumio [KEK; Konomi, T. [KEK; Saito, Kenji [KEK; Bice, Damon [Fermilab; Crawford, Anthony C. [JLAB; Geng, Rongli [JLAB

    2009-11-01

    We have continued high gradient R&D of ICHIRO 9-cell cavities at KEK. ICHIRO 9-cell cavity #5 (I9#5) that has no end groups on beam tube to focus on high gradient sent to Jlab as S0 tight loop study. Surface treatments and vertical test were repeated 3 times at Jlab, and then I9#5 sent back to KEK. We also repeated surface treatments and test at KEK. Maximum gradients were 36.5MV/m at Jlab, and 33.7MV/m at KEK so far. Now we are struggling with the puzzle why the results of singles do not work well on 9-cell cavities.

  1. A characterization of tight and dual generalized translation invariant frames

    DEFF Research Database (Denmark)

    Jakobsen, Mads Sielemann; Lemvig, Jakob

    2015-01-01

    , for each j we let Γj, be a closed subgroup of G such that G/Γj is compact. A GTI system is then the collection of functions UjεJ{gj, p(· - γ}γεΓj, pεPj. Many well known systems, such as wavelet, shearlet and Gabor systems, both the discrete and continuous types, are GTI systems. We characterize when...... such systems form tight frames, and when two GTI Bessel systems form dual frames for L2(G). In particular, this offers a unified approach to the theory of discrete and continuous frames and, e.g., yields well known results for discrete and continuous Gabor and wavelet systems....

  2. Zonulin, regulation of tight junctions, and autoimmune diseases.

    Science.gov (United States)

    Fasano, Alessio

    2012-07-01

    Recent studies indicate that besides digestion and absorption of nutrients and water and electrolytes homeostasis, another key function of the intestine is to regulate the trafficking of environmental antigens across the host mucosal barrier. Intestinal tight junctions (TJs) create gradients for the optimal absorption and transport of nutrients and control the balance between tolerance and immunity to nonself antigens. To meet diverse physiological challenges, intestinal epithelial TJs must be modified rapidly and in a coordinated fashion by regulatory systems that orchestrate the state of assembly of the TJ multiprotein network. While considerable knowledge exists about TJ ultrastructure, relatively little is known about their physiological and pathophysiological regulation. Our discovery of zonulin, the only known physiologic modulator of intercellular TJs described so far, has increased our understanding of the intricate mechanisms that regulate the intestinal epithelial paracellular pathway and has led us to appreciate that its upregulation in genetically susceptible individuals leads to autoimmune diseases. © 2012 New York Academy of Sciences.

  3. Proceedings of the natural gas research and development contractors review meeting

    Energy Technology Data Exchange (ETDEWEB)

    Malone, R.D.; Shoemaker, H.D.; Byrer, C.W. (eds.)

    1990-11-01

    The purpose of this meeting was to present results of the research in the DOE-sponsored Natural Gas Program, and simultaneously to provide a forum for real-time technology transfer, to the active research community, to the interested public, and to the natural gas industry, who are the primary users of this technology. The current research focus is to expand the base of near-term and mid-term economic gas resources through research activities in Eastern Tight Gas, Western Tight Gas, Secondary Gas Recovery (increased recovery of gas from mature fields); to enhance utilization, particularly of remote gas resources through research in Natural Gas to Liquids Conversion; and to develop additional, long term, potential gas resources through research in Gas Hydrates and Deep Gas. With the increased national emphasis on the use of natural gas, this forum has been expanded to include summaries of DOE-sponsored research in energy-related programs and perspectives on the importance of gas to future world energy. Thirty-two papers and fourteen poster presentations were given in seven formal, and one informal, sessions: Three general sessions (4 papers); Western Tight Gas (6 papers); Eastern Tight Gas (8 papers); Conventional/Speculative Resources (8 papers); and Gas to Liquids (6 papers). Individual reports are processed separately on the data bases.

  4. Effects of Tight Versus Non Tight Control of Metabolic Acidosis on Early Renal Function After Kidney Transplantation

    Directory of Open Access Journals (Sweden)

    Farhad Etezadi

    2012-09-01

    Full Text Available Background Recently, several studies have been conducted to determine the optimal strategy for intraoperative fluid replacement therapy in renal transplantation surgery. Since infusion of sodium bicarbonate as a buffer seems to be safer than other buffer compounds (lactate, gluconate, acetatethat indirectly convert into it within the liver, We hypothesized tight control of metabolic acidosis by infusion of sodium bicarbonate may improve early post-operative renal function in renal transplant recipients. Methods:120 patients were randomly divided into two equal groups. In group A, bicarbonate was infused intra-operatively according to Base Excess (BE measurements to achieve the normal values of BE (5 to +5 mEq/L. In group B, infusion of bicarbonate was allowed only in case of severe metabolic acidosis (BE [less than or equal to] 15 mEq/L or bicarbonate [less than or equal to] 10 mEq/L or PH [less than or equal to] 7.15. Minute ventilation was adjusted to keep PaCO2 within the normal range. Primary end-point was sampling of serum creatinine level in first, second, third and seventh post-operative days for statistical comparison between groups. Secondary objectives were comparison of cumulative urine volumes in the first 24 h of post-operative period and serum BUN levels which were obtained in first, second, third and seventh post-operative days. Results:In group A, all of consecutive serum creatinine levels were significantly lower in comparison with group B. With regard to secondary outcomes, no significant difference between groups was observed. Conclusion:Intra-operative tight control of metabolic acidosis by infusion of Sodium Bicarbonate in renal transplant recipients may improve early post-operative renal function.

  5. Effects of tight versus non tight control of metabolic acidosis on early renal function after kidney transplantation

    Directory of Open Access Journals (Sweden)

    Etezadi Farhad

    2012-09-01

    Full Text Available Abstract Background Recently, several studies have been conducted to determine the optimal strategy for intra-operative fluid replacement therapy in renal transplantation surgery. Since infusion of sodium bicarbonate as a buffer seems to be safer than other buffer compounds (lactate, gluconate, acetatethat indirectly convert into it within the liver, We hypothesized tight control of metabolic acidosis by infusion of sodium bicarbonate may improve early post-operative renal function in renal transplant recipients. Methods 120 patients were randomly divided into two equal groups. In group A, bicarbonate was infused intra-operatively according to Base Excess (BE measurements to achieve the normal values of BE (−5 to +5 mEq/L. In group B, infusion of bicarbonate was allowed only in case of severe metabolic acidosis (BE ≤ −15 mEq/L or bicarbonate ≤ 10 mEq/L or PH ≤ 7.15. Minute ventilation was adjusted to keep PaCO2 within the normal range. Primary end-point was sampling of serum creatinine level in first, second, third and seventh post-operative days for statistical comparison between groups. Secondary objectives were comparison of cumulative urine volumes in the first 24 h of post-operative period and serum BUN levels which were obtained in first, second, third and seventh post-operative days. Results In group A, all of consecutive serum creatinine levels were significantly lower in comparison with group B. With regard to secondary outcomes, no significant difference between groups was observed. Conclusion Intra-operative tight control of metabolic acidosis by infusion of Sodium Bicarbonate in renal transplant recipients may improve early post-operative renal function.

  6. Natural gas; Gas Natural

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Carlos A.; Moraes, Claudia C.D. [Eletricidade de Sao Paulo S.A. (ELETROPAULO), Sao Paulo, SP (Brazil); Fonseca, Carlos H.F. [Centrais Eletricas de Santa Catarina S.A., Florianopolis, SC (Brazil); Silva, Clecio Fabricio da; Alves, Ricardo P. [Companhia Paranaense de Energia (COPEL), Curitiba, PR (Brazil); Sposito, Edivaldo Soares; Hulle, Lutero [Espirito Santo Centrais Eletricas S.A. (ESCELSA), Vitoria, ES (Brazil); S. Martins, Icaro da [Centrais Eletricas do Norte do Brasil S.A. (ELETRONORTE), Belem, PA (Brazil); Vilhena, Joao Luiz S. de [Companhia Energetica de Minas Gerais (CEMIG), Belo Horizonte, MG (Brazil); Fagundes, Zaluar Aquino [Companhia Estadual de Energia Eletrica do Estado do Rio Grande do Sul, Porto Alegre, RS (Brazil)

    1996-12-31

    An increase in the consumption of natural gas in Brazil is an expected fact in what concerns energetic planning. This work presents the existing situation in what concerns natural gas utilization in the main world economies, as well as an analysis of the participation of this fuel among the energy final consumption per sources. The Brazilian consumption of natural gas is also analysed as well as the international agreement between Brazil and Bolivia for natural gas commercialization. Some legal, institutional and political aspects related to natural gas commercialization are also discussed. Finally, several benefits to be brought by the utilization of natural gas are presented 10 refs., 3 tabs.

  7. Experimental and simulation determination of minimum miscibility pressure for a Bakken tight oil and different injection gases

    Directory of Open Access Journals (Sweden)

    Sheng Li

    2017-03-01

    Full Text Available The effective development of unconventional tight oil formations, such as Bakken, could include CO2 enhanced oil recovery (EOR technologies with associated benefits of capturing and storing large quantities of CO2. It is important to conduct the gas injection at miscible condition so as to reach maximum recovery efficiency. Therefore, determination of the minimum miscibility pressure (MMP of reservoir live oil–injection gas system is critical in a miscible gas flooding project design. In this work, five candidate injection gases, namely CO2, CO2-enriched flue gas, natural gas, nitrogen, and CO2-enriched natural gas, were selected and their MMPs with a Bakken live oil were determined experimentally and numerically. At first, phase behaviour tests were conducted for the reconstituted Bakken live oil and the gases. CO2 outperformed other gases in terms of viscosity reduction and oil swelling. Rising bubble apparatus (RBA determined live oil–CO2 MMP as 11.9 MPa and all other gases higher than 30 MPa. The measured phase behaviour data were used to build and tune an equation-of-state (EOS model, which calculated the MMPs for different live oil-gas systems. The EOS-based calculations indicated that CO2 had the lowest MMP with live oil among the five gases in the study. At last, the commonly-accepted Alston et al. equation was used to calculate live oil–pure CO2 MMP and effect of impurities in the gas phase on MMP change. The Bakken oil–CO2 had a calculated MMP of 10.3 MPa from the Alston equation, and sensitivity analysis showed that slight addition of volatile impurities, particularly N2, can increase MMP significantly.

  8. Gas and Gas Pains

    Science.gov (United States)

    ... Gas and gas pains Symptoms & causes Diagnosis & treatment Advertisement Mayo Clinic does not endorse companies or products. ... a Job Site Map About This Site Twitter Facebook Google YouTube Pinterest Mayo Clinic is a not- ...

  9. Upper Paleozoic coal measures and unconventional natural gas systems of the Ordos Basin, China

    Directory of Open Access Journals (Sweden)

    Xuan Tang

    2012-11-01

    Full Text Available Upper Paleozoic coal measures in the Ordos Basin consist of dark mudstone and coal beds and are important source rocks for gas generation. Gas accumulations include coal-bed methane (CBM, tight gas and conventional gas in different structural areas. CBM accumulations are mainly distributed in the marginal area of the Ordos Basin, and are estimated at 3.5 × 1012 m3. Tight gas accumulations exist in the middle part of the Yishan Slope area, previously regarded as the basin-centered gas system and now considered as stratigraphic lithologic gas reservoirs. This paper reviews the characteristics of tight gas accumulations: poor physical properties (porosity < 8%, permeability < 0.85 × 10−3 μm2, abnormal pressure and the absence of well-defined gas water contacts. CBM is a self-generation and self-reservoir, while gas derived from coal measures migrates only for a short distance to accumulate in a tight reservoir and is termed near-generation and near-reservoir. Both CBM and tight gas systems require source rocks with a strong gas generation ability that extends together over wide area. However, the producing area of the two systems may be significantly different.

  10. Tight-binding model for materials at mesoscale

    Energy Technology Data Exchange (ETDEWEB)

    2016-12-21

    TBM3 is an open source package for computational simulations of quantum materials at multiple scales in length and time. The project originated to investigate the multiferroic behavior in transition-metal oxide heterostructures. The framework has also been designed to study emergent phemona in other quantum materials like 2-dimensional transition-metal dichalcogenides, graphene, topological insulators, and skyrmion in materials, etc. In the long term, we will enable the package for transport and time-resolved phenomena. TBM3 is currently a C++ based numerical tool package and framework for the design and construction of any kind of lattice structures with multi-orbital and spin degrees of freedom. The fortran based portion of the package will be added in the near future. The design of TBM3 is in a highly flexible and reusable framework and the tight-binding parameters can be modeled or informed by DFT calculations. It is currently GPU enabled and feature of CPU enabled MPI will be added in the future.

  11. Tight binding of NAP-22 with acidic membrane lipids.

    Science.gov (United States)

    Maekawa, Shohei; Kobayashi, Yuumi; Morita, Mitsuhiro; Suzaki, Toshinobu

    2015-07-23

    Recovery of various signal transduction molecules in the detergent-resistant membrane microdomain (DRM) fraction suggests the importance of this region in cellular functions. Insolubility of the outer leaflet of DRM to the non-ionic detergent is ascribed to the tight association of cholesterol and sphingolipid. Since, poor localization of sphingolipid is observed in the inner leaflet, the physicochemical background of the insolubility of the inner leaflet is hence still an enigma. NAP-22 (also called BASP1 or CAP-23) is a neuron-enriched calmodulin-binding protein and one of the major proteins in the DRM of the neuronal cell membrane. A previous study showed the presence of several lipids in a NAP-22 fraction after the process of extraction and column chromatography. In this study, the effect of lipid extraction on NAP-22 was studied through native-gel electrophoresis, ultracentrifugation, and electron microscopic observation. The mobility of NAP-22 in native-PAGE was shifted from low to high after delipidation. Delipidated NAP-22 bound phosphatidylserine (PS), phosphatidylinosotol, and ganglioside. Some part of the mixture of PS and NAP-22 was recovered in the insoluble fraction after Triton X-100 treatment and the addition of cholesterol enhanced the amount of NAP-22 in the insoluble fraction. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

  12. The role of tight junctions in mammary gland function.

    Science.gov (United States)

    Stelwagen, Kerst; Singh, Kuljeet

    2014-03-01

    Tight junctions (TJ) are cellular structures that facilitate cell-cell communication and are important in maintaining the three-dimensional structure of epithelia. It is only during the last two decades that the molecular make-up of TJ is becoming unravelled, with two major transmembrane-spanning structural protein families, called occludin and claudins, being the true constituents of the TJ. These TJ proteins are linked via specific scaffolding proteins to the cell's cytoskeleton. In the mammary gland TJ between adjacent secretory epithelial cells are formed during lactogenesis and are instrumental in establishing and maintaining milk synthesis and secretion, whereas TJ integrity is compromised during mammary involution and also as result of mastitis and periods of mammary inflamation (including mastitis). They prevent the paracellular transport of ions and small molecules between the blood and milk compartments. Formation of intact TJ at the start of lactation is important for the establishment of the lactation. Conversely, loss of TJ integrity has been linked to reduced milk secretion and mammary function and increased paracellular transport of blood components into the milk and vice versa. In addition to acting as a paracellular barrier, the TJ is increasingly linked to playing an active role in intracellular signalling. This review focusses on the role of TJ in mammary function of the normal, non-malignant mammary gland, predominantly in ruminants, the major dairy producing species.

  13. Testing underground tanks for leak tightness at LLNL

    International Nuclear Information System (INIS)

    Henry, R.K.; Sites, R.L.; Sledge, M.

    1986-01-01

    Two types of tank systems are present at the Livermore Site: tanks and associated piping for the storage of fuel (forty-three systems), and tanks or sumps and associated piping for the retention of potentially contaminated wastewater (forty systems). The fuel systems were tested using commercially available test methods: Petro-Tite, Hunter Leak Lokator, Ezy-Chek, and Associated Environmental Systems (A.E.S.). In contrast to fuel tank systems, wastewater systems have containers that are predominantly open at the top and not readily testable. Therefore, a project to test and evaluate all available testing methods was initiated and completed. The commercial method Tank Auditor was determined to be appropriate for testing open-top tanks and sumps and this was the method used to test the majority of the open-top containers. Of the 81 tanks tested, 61 were found to be leak tight, 9 were shown to have leaks, and 11 yielded inconclusive results. Two tanks have not yet been tested because of operational constraints; they are sheduled to be tested within the next two months. Schedules are being developed for the retesting of tanks and for remedial actions

  14. Characterization of Tight Junction Proteins in Cultured Human Urothelial Cells

    Science.gov (United States)

    Rickard, Alice; Dorokhov, Nikolay; Ryerse, Jan; Klumpp, David J.; McHowat, Jane

    2010-01-01

    Tight junctions (TJs) are essential for normal function of epithelia, restricting paracellular diffusion and contributing to the maintainance of cell surface polarity. Superficial cells of the urothelium develop TJs, the basis for the paracellular permeability barrier of the bladder against diffusion of urinary solutes. Focusing on the superficial cell layer of stratified cell cultures of an immortalized human ureteral cell line, TEU-2 cells, we have examined the presence of TJ and TJ-associated proteins. TEU-2 cells were treated with calcium chloride and fetal bovine serum culture conditions used to induce stratification that resembles the normal transitional epithelial phenotype. Cultures were examined for TJ and TJ-associated proteins by confocal immuno-fluorescence microscopy and evaluated for TJ mRNA by reverse transcriptase-polymerase chain reaction (RT- PCR). TEU-2 cultures exhibited immunoreactivity at intercellular margins for claudins 1, 4, 5, 7, 14 and 16 whereas claudins 2, 8 and 12 were intracellular. RT-PCR corroborated the presence of these claudins at the mRNA level. The TJ-associated proteins occludin, JAM-1, and zonula occludens (ZO-1, ZO-2 and ZO-3) were localized at cell margins. We have found that numerous TJs and TJ-associated proteins are expressed in stratified TEU-2 cultures. Further, we propose TEU-2s provide a useful ureteral model for future studies on the involvement of TJs proteins in the normal and pathological physiology of the human urinary system. PMID:18553212

  15. End-of-fill study on collimator tight settings

    CERN Document Server

    Assmann, R; Burkart, F; Cauchi, M; Deboy, D; Redaelli, S; Rossi, A; Schmidt, R; Valentino, G; Wollmann, D

    2012-01-01

    In 2010 and 2011 the collimation system has been operated with relaxed settings, i.e. with retractions between different collimator families larger than the nominal settings that provide optimum cleaning. This configuration ensured a sufficient cleaning performance at 3.5 TeV while allowing larger tolerances on orbit control. Tighter collimator settings were proposed to push the cleaning performance and to allow larger orbit margins between TCDQ dump protection and tertiary collimators, which opens the possibility to push further the LHC β* reach. After having verified with beam that the cleaning is improved as expected, the feasibility of tighter collimator settings must be addressed with high stored intensity. For this purpose, an end-of-fill study was proposed after a standard physics fill with 1380 bunches nominal bunches at 3.5 TeV, for a total stored energy of 95 MJ. During this test, primary and secondary collimators were moved to that tight settings after about 8 hours of stable physics conditions in...

  16. Fuel assembly leak tightness control on WWER-1000 reactor

    International Nuclear Information System (INIS)

    Ivanova, R.; Gerchev, N.; Mateev, A.

    2001-01-01

    The main index for integrity of the fuel rods cladding is the specific activity value of the primary coolant. This value determines the safe operation of the reactor. The limit for safe operation of WWER-1000 reactor is the value of the total activity of Iodine isotopes in the primary coolant 5.0x10 -3 Ci/l. The paper briefly describes the methodology for performing a fuel tightness test (sipping test) and shows the results from these tests performed during the period 1987 -1999 in units 5 and 6 at the Kozloduy NPP. An additional index related to the safe operation is defined to characterize the fuel cladding integrity Fuel Reliability Index (FRI). The FRI is defined as value of the average activity of 131 I in the primary coolant, corrected with a part of precipitated 235 U migration and fixed to the general permanent purification frequency. Two criteria (quantitative and statistic) are determined to qualify the fuel cladding integrity. The results from sipping tests show good reliability of the fuel irradiated in unit 5 and 6 at the Kozloduy NPP

  17. Nanoscale capacitance: A quantum tight-binding model

    Science.gov (United States)

    Zhai, Feng; Wu, Jian; Li, Yang; Lu, Jun-Qiang

    2017-01-01

    Landauer-Buttiker formalism with the assumption of semi-infinite electrodes as reservoirs has been the standard approach in modeling steady electron transport through nanoscale devices. However, modeling dynamic electron transport properties, especially nanoscale capacitance, is a challenging problem because of dynamic contributions from electrodes, which is neglectable in modeling macroscopic capacitance and mesoscopic conductance. We implement a self-consistent quantum tight-binding model to calculate capacitance of a nano-gap system consisting of an electrode capacitance C‧ and an effective capacitance Cd of the middle device. From the calculations on a nano-gap made of carbon nanotube with a buckyball therein, we show that when the electrode length increases, the electrode capacitance C‧ moves up while the effective capacitance Cd converges to a value which is much smaller than the electrode capacitance C‧. Our results reveal the importance of electrodes in modeling nanoscale ac circuits, and indicate that the concepts of semi-infinite electrodes and reservoirs well-accepted in the steady electron transport theory may be not applicable in modeling dynamic transport properties.

  18. Air-tight disposing device for solid radioactive waste

    International Nuclear Information System (INIS)

    Aoyama, Saburo.

    1976-01-01

    Object: In a construction for air-tightly connecting radioactive material handling equipment with a radioactive waste container through a vinyl bag, to use a multi-stage expansion tube to introduce the radioactive waste into the waste container in safe and positive manner. Structure: During normal operation in the radioactive material handling equipment, a multi-stage expansion cylinder is extended by operation of a remote shaft to suitably throw the waste in a state with a vinyl bag protected, whereas when the waste is disposed away from the equipment, the multi-stage expansion cylinder is contracted and received into a holder, and the vinyl bag is heated and sealed at a given position and cut, after which a cover of an outer container for disposal is closed and carried out. The vinyl bag remained on the side of the holder after sealed and cut is put into the waste container after a fresh vinyl bag, in which another waste container is received, has been secured to the holder. (Taniai, N.)

  19. Pre-Darcy flow in tight and shale formations

    Science.gov (United States)

    Dejam, Morteza; Hassanzadeh, Hassan; Chen, Zhangxin

    2017-11-01

    There are evidences that the fluid flow in tight and shale formations does not follow Darcy law, which is identified as pre-Darcy flow. Here, the unsteady linear flow of a slightly compressible fluid under the action of pre-Darcy flow is modeled and a generalized Boltzmann transformation technique is used to solve the corresponding highly nonlinear diffusivity equation analytically. The effect of pre-Darcy flow on the pressure diffusion in a homogenous formation is studied in terms of the nonlinear exponent, m, and the threshold pressure gradient, G1. In addition, the pressure gradient, flux, and cumulative production per unit area for different m and G1 are compared with the classical solution of the diffusivity equation based on Darcy flow. Department of Petroleum Engineering in College of Engineering and Applied Science at University of Wyoming and NSERC/AI-EES(AERI)/Foundation CMG and AITF (iCORE) Chairs in Department of Chemical and Petroleum Engineering at University of Calgary.

  20. Claudin-21 Has a Paracellular Channel Role at Tight Junctions

    KAUST Repository

    Tanaka, Hiroo

    2016-01-05

    Claudin protein family members, of which there are at least 27 in humans and mice, polymerize to form tight junctions (TJs) between epithelial cells, in a tissue- and developmental stage-specific manner. Claudins have a paracellular barrier function. In addition, certain claudins function as paracellular channels for small ions and/or solutes by forming selective pores at the TJs, although the specific claudins involved and their functional mechanisms are still in question. Here we show for the first time that claudin-21, which is more highly expressed in the embryonic than the postnatal stages, acts as a paracellular channel for small cations, such as Na+, similar to the typical channel-type claudins claudin-2 and -15. Claudin-21 also allows the paracellular passage of larger solutes. Our findings suggest that claudin-21-based TJs allow the passage of small and larger solutes by both paracellular channel-based and some additional mechanisms. © 2016, American Society for Microbiology. All Rights Reserved.

  1. Intestinal epithelial barrier function and tight junction proteins with heat and exercise

    DEFF Research Database (Denmark)

    Dokladny, Karol; Zuhl, Micah N; Moseley, Pope L

    2016-01-01

    (passive hyperthermia) heat stress on tight junction barrier function in in vitro and in vivo (animals and humans) models. Our secondary focus is to review changes in tight junction proteins in response to exercise or hyperthermic conditions. Finally, we discuss some pharmacological or nutritional...... interventions that may affect the cellular mechanisms involved in maintaining homeostasis of the intestinal epithelial tight junction barrier during heat stress or exercise....... permeation of luminal antigens, endotoxins, and bacteria into the blood stream. Various substances and conditions have been shown to affect the maintenance of the intestinal epithelial tight junction barrier. The primary focus of the present review is to analyze the effects of exertional or nonexertional...

  2. A hydrogen leak-tight, transparent cryogenic sample container for ultracold-neutron transmission measurements

    Science.gov (United States)

    Döge, Stefan; Hingerl, Jürgen

    2018-03-01

    The improvement of the number of extractable ultracold neutrons (UCNs) from converters based on solid deuterium (sD2) crystals requires a good understanding of the UCN transport and how the crystal's morphology influences its transparency to the UCNs. Measurements of the UCN transmission through cryogenic liquids and solids of interest, such as hydrogen (H2) and deuterium (D2), require sample containers with thin, highly polished and optically transparent windows and a well defined sample thickness. One of the most difficult sealing problems is that of light gases like hydrogen and helium at low temperatures against high vacuum. Here we report on the design of a sample container with two 1 mm thin amorphous silica windows cold-welded to aluminum clamps using indium wire gaskets, in order to form a simple, reusable, and hydrogen-tight cryogenic seal. The container meets the above-mentioned requirements and withstands up to 2 bar hydrogen gas pressure against isolation vacuum in the range of 10-5 to 10-7 mbar at temperatures down to 4.5 K. Additionally, photographs of the crystallization process are shown and discussed.

  3. A hydrogen leak-tight, transparent cryogenic sample container for ultracold-neutron transmission measurements.

    Science.gov (United States)

    Döge, Stefan; Hingerl, Jürgen

    2018-03-01

    The improvement of the number of extractable ultracold neutrons (UCNs) from converters based on solid deuterium (sD 2 ) crystals requires a good understanding of the UCN transport and how the crystal's morphology influences its transparency to the UCNs. Measurements of the UCN transmission through cryogenic liquids and solids of interest, such as hydrogen (H 2 ) and deuterium (D 2 ), require sample containers with thin, highly polished and optically transparent windows and a well defined sample thickness. One of the most difficult sealing problems is that of light gases like hydrogen and helium at low temperatures against high vacuum. Here we report on the design of a sample container with two 1 mm thin amorphous silica windows cold-welded to aluminum clamps using indium wire gaskets, in order to form a simple, reusable, and hydrogen-tight cryogenic seal. The container meets the above-mentioned requirements and withstands up to 2 bar hydrogen gas pressure against isolation vacuum in the range of 10 -5 to 10 -7 mbar at temperatures down to 4.5 K. Additionally, photographs of the crystallization process are shown and discussed.

  4. Forecasting world natural gas supply

    International Nuclear Information System (INIS)

    Al-Fattah, S. M.; Startzman, R. A.

    2000-01-01

    Using the multi-cyclic Hubert approach, a 53 country-specific gas supply model was developed which enables production forecasts for virtually all of the world's gas. Supply models for some organizations such as OPEC, non-OPEC and OECD were also developed and analyzed. Results of the modeling study indicate that the world's supply of natural gas will peak in 2014, followed by an annual decline at the rate of one per cent per year. North American gas production is reported to be currently at its peak with 29 Tcf/yr; Western Europe will reach its peak supply in 2002 with 12 Tcf. According to this forecast the main sources of natural gas supply in the future will be the countries of the former Soviet Union and the Middle East. Between them, they possess about 62 per cent of the world's ultimate recoverable natural gas (4,880 Tcf). It should be noted that these estimates do not include unconventional gas resulting from tight gas reservoirs, coalbed methane, gas shales and gas hydrates. These unconventional sources will undoubtedly play an important role in the gas supply in countries such as the United States and Canada. 18 refs., 2 tabs., 18 figs

  5. Urothelial Tight Junction Barrier Dysfunction Sensitizes Bladder Afferents

    Science.gov (United States)

    Rued, Anna C.; Taiclet, Stefanie N.; Birder, Lori A.; Kullmann, F. Aura

    2017-01-01

    Abstract Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic voiding disorder that presents with pain in the urinary bladder and surrounding pelvic region. A growing body of evidence suggests that an increase in the permeability of the urothelium, the epithelial barrier that lines the interior of the bladder, contributes to the symptoms of IC/BPS. To examine the consequence of increased urothelial permeability on pelvic pain and afferent excitability, we overexpressed in the urothelium claudin 2 (Cldn2), a tight junction (TJ)-associated protein whose message is significantly upregulated in biopsies of IC/BPS patients. Consistent with the presence of bladder-derived pain, rats overexpressing Cldn2 showed hypersensitivity to von Frey filaments applied to the pelvic region. Overexpression of Cldn2 increased the expression of c-Fos and promoted the activation of ERK1/2 in spinal cord segments receiving bladder input, which we conceive is the result of noxious stimulation of afferent pathways. To determine whether the mechanical allodynia observed in rats with reduced urothelial barrier function results from altered afferent activity, we examined the firing of acutely isolated bladder sensory neurons. In patch-clamp recordings, about 30% of the bladder sensory neurons from rats transduced with Cldn2, but not controls transduced with GFP, displayed spontaneous activity. Furthermore, bladder sensory neurons with tetrodotoxin-sensitive (TTX-S) action potentials from rats transduced with Cldn2 showed hyperexcitability in response to suprathreshold electrical stimulation. These findings suggest that as a result of a leaky urothelium, the diffusion of urinary solutes through the urothelial barrier sensitizes bladders afferents, promoting voiding at low filling volumes and pain. PMID:28560313

  6. Tightness of M-estimators for multiple linear regression in time series

    DEFF Research Database (Denmark)

    Johansen, Søren; Nielsen, Bent

    We show tightness of a general M-estimator for multiple linear regression in time series. The positive criterion function for the M-estimator is assumed lower semi-continuous and sufficiently large for large argument: Particular cases are the Huber-skip and quantile regression. Tightness requires...

  7. A theoretical investigation of tight-binding thermolysin inhibitors.

    Science.gov (United States)

    Shen, J

    1997-08-29

    A tight-binding thermolysin inhibitor, Cbz-Phe-psi[PO2NH]-Leu-Ala (ZFpLA, Ki = 0.068 nM), and its analogs, ZRp(O)LA (R = Ala, Leu or Phe) have been studied using the finite difference solution to the linearized Poisson-Boltzmann equation (FDPB) and solvation entropy correction (SEC). The binding energy difference between conformationally different thermolysin inhibitors ZFpLA and ZGpLL is estimated using three approaches. Two of approaches use the X-ray structures of ZFpLA-thermolysin and ZGpLL-thermolysin structures. The third one uses both X-ray structures to calculate binding energy differences from ZFpLA and ZGpLL to a hypothetical intermediate MepLA. All the results are qualitatively correct with one closely reproducing the experimental value. The enhancement of the ZFpLA binding is attributed largely to the solvation entropy or "hydrophobic force". The binding mode of the ZGpLR N-terminal moiety appears to be electrostatically unfavorable. Reducing the polarity of that moiety is predicted to enhance binding affinity. The binding trends due to the hydrophobic variation of ZRp(O)LA are calculated within 1 kcal/mol of the experimental values. Increasing lipophilicity of a ligand favors the binding due to the difference of surface area change between the free state and the bound state. The analysis of energetic components shows that these trends are not specific for the binding of phosphorus-containing inhibitors but are generally true for protein-ligand interactions. The electrostatic calculation does not support the involvement of the second protonation of ZFpLA in binding. Therefore, reexamining the second protonation of ZFpLA or seeking further experimental support seems appropriate. The structural sensitivity of the FDPB calculation was assessed by using ligand and receptor structures from different X-ray studies of thermolysin. The small deviations (< 0.3 A) in the receptor structures do not cause significant changes in electrostatic binding energy if there

  8. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV) Fracturing in Tight Oil Reservoirs.

    Science.gov (United States)

    Su, Yuliang; Ren, Long; Meng, Fankun; Xu, Chen; Wang, Wendong

    2015-01-01

    Stimulated reservoir volume (SRV) fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM), mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP) and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  9. Theoretical Analysis of the Mechanism of Fracture Network Propagation with Stimulated Reservoir Volume (SRV Fracturing in Tight Oil Reservoirs.

    Directory of Open Access Journals (Sweden)

    Yuliang Su

    Full Text Available Stimulated reservoir volume (SRV fracturing in tight oil reservoirs often induces complex fracture-network growth, which has a fundamentally different formation mechanism from traditional planar bi-winged fracturing. To reveal the mechanism of fracture network propagation, this paper employs a modified displacement discontinuity method (DDM, mechanical mechanism analysis and initiation and propagation criteria for the theoretical model of fracture network propagation and its derivation. A reasonable solution of the theoretical model for a tight oil reservoir is obtained and verified by a numerical discrete method. Through theoretical calculation and computer programming, the variation rules of formation stress fields, hydraulic fracture propagation patterns (FPP and branch fracture propagation angles and pressures are analyzed. The results show that during the process of fracture propagation, the initial orientation of the principal stress deflects, and the stress fields at the fracture tips change dramatically in the region surrounding the fracture. Whether the ideal fracture network can be produced depends on the geological conditions and on the engineering treatments. This study has both theoretical significance and practical application value by contributing to a better understanding of fracture network propagation mechanisms in unconventional oil/gas reservoirs and to the improvement of the science and design efficiency of reservoir fracturing.

  10. The conundrum of lenticular oncology. A review

    Directory of Open Access Journals (Sweden)

    Chaturvedi Sunil

    2003-01-01

    Full Text Available It is a long - accepted dogma in ophthalmology that the lens is a tumour-free tissue. Yet, in the lens, there is lifelong mitotic activity in the subcapsular epithelium. Therefore, these subcapsular epithelial cells must have the potential for cellular transformation. How then can we explain the fact that no scientist has ever seen a naturally occurring primary tumour of the lens in vivo ? This review discusses the early work of Mann, von Hallermann, Courtois and others who addressed the issue of tumour resistance of the lens.

  11. Canadian gas resource

    International Nuclear Information System (INIS)

    Anon.

    1989-01-01

    Canadian exports of gas to the United States are a critical component of EMF-9 (North American Gas Supplies). However, it has been noted that there are differences between US expectations for imports and Canadian forecasts of export supply capacity. Recent studies by the National Petroleum Council (NPC) and the US Department of Energy (DOE) indicate that 1.8 to 2.4 Tcf of imports may be required in the mid to late 1990's; A recent study by Canada's National Energy Board (NEB) indicates that the conventional resource base may not be able to provide continued gas exports to the US after the mid 1990's and that frontier sources would need to be developed to meet US expectations. The discrepancies between US expectations and Canadian estimates of capacity are of great concern to US policymakers because they call into question the availability of secure supplies of natural gas and suggest that the cost of imports (if available) will be high. By implication, if shortages are to be averted, massive investment may be required to bring these higher cost sources to market. Since the long-term supply picture will be determined by the underlying resource base, EMF-9 participants have been asked to provide estimates of critical components of the Canadian resource base. This paper provides a summary of ICF-Lewin's recent investigation of both the Conventional and Tight Gas resource in Canada's Western Sedimentary Basin, which includes both quantitative estimates and a brief sketch of the analysis methodology

  12. Water management technologies used by Marcellus Shale Gas Producers.

    Energy Technology Data Exchange (ETDEWEB)

    Veil, J. A.; Environmental Science Division

    2010-07-30

    Natural gas represents an important energy source for the United States. According to the U.S. Department of Energy's (DOE's) Energy Information Administration (EIA), about 22% of the country's energy needs are provided by natural gas. Historically, natural gas was produced from conventional vertical wells drilled into porous hydrocarbon-containing formations. During the past decade, operators have increasingly looked to other unconventional sources of natural gas, such as coal bed methane, tight gas sands, and gas shales.

  13. Proteomic and bioinformatic analysis of epithelial tight junction reveals an unexpected cluster of synaptic molecules

    Directory of Open Access Journals (Sweden)

    Tang Vivian W

    2006-12-01

    Full Text Available Abstract Background Zonula occludens, also known as the tight junction, is a specialized cell-cell interaction characterized by membrane "kisses" between epithelial cells. A cytoplasmic plaque of ~100 nm corresponding to a meshwork of densely packed proteins underlies the tight junction membrane domain. Due to its enormous size and difficulties in obtaining a biochemically pure fraction, the molecular composition of the tight junction remains largely unknown. Results A novel biochemical purification protocol has been developed to isolate tight junction protein complexes from cultured human epithelial cells. After identification of proteins by mass spectroscopy and fingerprint analysis, candidate proteins are scored and assessed individually. A simple algorithm has been devised to incorporate transmembrane domains and protein modification sites for scoring membrane proteins. Using this new scoring system, a total of 912 proteins have been identified. These 912 hits are analyzed using a bioinformatics approach to bin the hits in 4 categories: configuration, molecular function, cellular function, and specialized process. Prominent clusters of proteins related to the cytoskeleton, cell adhesion, and vesicular traffic have been identified. Weaker clusters of proteins associated with cell growth, cell migration, translation, and transcription are also found. However, the strongest clusters belong to synaptic proteins and signaling molecules. Localization studies of key components of synaptic transmission have confirmed the presence of both presynaptic and postsynaptic proteins at the tight junction domain. To correlate proteomics data with structure, the tight junction has been examined using electron microscopy. This has revealed many novel structures including end-on cytoskeletal attachments, vesicles fusing/budding at the tight junction membrane domain, secreted substances encased between the tight junction kisses, endocytosis of tight junction

  14. Tight Money, Real Interest Rates, and Inflation in Sub-Saharan Africa

    OpenAIRE

    Edward F. Buffie

    2003-01-01

    The consequences of tight monetary policy are analyzed in an optimizing currency-substitution model of a small, open economy that operates under an open capital account and a flexible exchange rate. There is a reasonably good fit between the dynamics generated by the model and the stylized facts in the tight-money episodes that occurred in Kenya in 1993 and Nigeria in 1989-91. The study's results shed light on two issues: why tight money has provoked stupendous increases in inflation and the ...

  15. Hibernation and gas exchange.

    Science.gov (United States)

    Milsom, William K; Jackson, Donald C

    2011-01-01

    Hibernation in endotherms and ectotherms is characterized by an energy-conserving metabolic depression due to low body temperatures and poorly understood temperature-independent mechanisms. Rates of gas exchange are correspondly reduced. In hibernating mammals, ventilation falls even more than metabolic rate leading to a relative respiratory acidosis that may contribute to metabolic depression. Breathing in some mammals becomes episodic and in some small mammals significant apneic gas exchange may occur by passive diffusion via airways or skin. In ectothermic vertebrates, extrapulmonary gas exchange predominates and in reptiles and amphibians hibernating underwater accounts for all gas exchange. In aerated water diffusive exchange permits amphibians and many species of turtles to remain fully aerobic, but hypoxic conditions can challenge many of these animals. Oxygen uptake into blood in both endotherms and ectotherms is enhanced by increased affinity of hemoglobin for O₂ at low temperature. Regulation of gas exchange in hibernating mammals is predominately linked to CO₂/pH, and in episodic breathers, control is principally directed at the duration of the apneic period. Control in submerged hibernating ectotherms is poorly understood, although skin-diffusing capacity may increase under hypoxic conditions. In aerated water blood pH of frogs and turtles either adheres to alphastat regulation (pH ∼8.0) or may even exhibit respiratory alkalosis. Arousal in hibernating mammals leads to restoration of euthermic temperature, metabolic rate, and gas exchange and occurs periodically even as ambient temperatures remain low, whereas body temperature, metabolic rate, and gas exchange of hibernating ectotherms are tightly linked to ambient temperature. © 2011 American Physiological Society.

  16. Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight, so ambient light will increase the noise and may even damage them.

    CERN Multimedia

    Nooren, G.

    2004-01-01

    Installation of the light tight cover for the SSD modules (the modules are behind the aluminium plate). The silicon sensors are sensitive to light tight , so ambient light will increase the noise and may even damage them.

  17. 49 CFR 571.304 - Standard No. 304; Compressed natural gas fuel container integrity.

    Science.gov (United States)

    2010-10-01

    ....4.1. Liner means the inner gas tight container or gas cylinder to which the overwrap is applied... statement: “If there is a question about the proper use, installation, or maintenance of this container... 49 Transportation 6 2010-10-01 2010-10-01 false Standard No. 304; Compressed natural gas fuel...

  18. Empirical tight-binding modeling of ordered and disordered semiconductor structures; Empirische Tight-Binding-Modellierung geordneter und ungeordneter Halbleiterstrukturen

    Energy Technology Data Exchange (ETDEWEB)

    Mourad, Daniel

    2010-11-30

    In this thesis, we investigate the electronic and optical properties of pure as well as of substitutionally alloyed II-VI and III-V bulk semiconductors and corresponding semiconductor quantum dots by means of an empirical tight-binding (TB) model. In the case of the alloyed systems of the type A{sub x}B{sub 1-x}, where A and B are the pure compound semiconductor materials, we study the influence of the disorder by means of several extensions of the TB model with different levels of sophistication. Our methods range from rather simple mean-field approaches (virtual crystal approximation, VCA) over a dynamical mean-field approach (coherent potential approximation, CPA) up to calculations where substitutional disorder is incorporated on a finite ensemble of microscopically distinct configurations. In the first part of this thesis, we cover the necessary fundamentals in order to properly introduce the TB model of our choice, the effective bond-orbital model (EBOM). In this model, one s- and three p-orbitals per spin direction are localized on the sites of the underlying Bravais lattice. The matrix elements between these orbitals are treated as free parameters in order to reproduce the properties of one conduction and three valence bands per spin direction and can then be used in supercell calculations in order to model mixed bulk materials or pure as well as mixed quantum dots. Part II of this thesis deals with unalloyed systems. Here, we use the EBOM in combination with configuration interaction calculations for the investigation of the electronic and optical properties of truncated pyramidal GaN quantum dots embedded in AlN with an underlying zincblende structure. Furthermore, we develop a parametrization of the EBOM for materials with a wurtzite structure, which allows for a fit of one conduction and three valence bands per spin direction throughout the whole Brillouin zone of the hexagonal system. In Part III, we focus on the influence of alloying on the electronic

  19. Optimal Pretreatment System of Flowback Water from Shale Gas Production

    OpenAIRE

    Carrero-Parreño, Alba; Onishi, Viviani C.; Salcedo Díaz, Raquel; Ruiz-Femenia, Rubén; Fraga, Eric S.; Caballero, José A.; Reyes-Labarta, Juan A.

    2017-01-01

    Shale gas has emerged as a potential resource to transform the global energy market. Nevertheless, gas extraction from tight shale formations is only possible after horizontal drilling and hydraulic fracturing, which generally demand large amounts of water. Part of the ejected fracturing fluid returns to the surface as flowback water, containing a variety of pollutants. For this reason, water reuse and water recycling technologies have received further interest for enhancing overall shale gas...

  20. Paracellin-1, a renal tight junction protein required for paracellular Mg2+ resorption

    NARCIS (Netherlands)

    Simon, DB; Lu, Y; Choate, KA; Velazquez, H; Al-Sabban, E; Praga, M; Casari, C; Bettinelli, A; Colussi, C; Rodriguez-Soriano, J; McCredie, D; Milford, D; Sanjad, S; Lifton, RP

    1999-01-01

    Epithelia permit selective and regulated flux from apical to basolateral surfaces by transcellular passage through cells or paracellular flux between cells. Tight junctions constitute the barrier to paracellular conductance; however, Little is known about the specific molecules that mediate

  1. Possible Involvement of Tight Junctions, Extracellular Matrix and Nuclear Receptors in Epithelial Differentiation

    OpenAIRE

    Ichikawa-Tomikawa, Naoki; Sugimoto, Kotaro; Satohisa, Seiro; Nishiura, Keisuke; Chiba, Hideki

    2011-01-01

    Tight junctions are intercellular junctions localized at the most apical end of the lateral plasma membrane. They consist of four kinds of transmembrane proteins (occludin, claudins, junctional adhesion molecules, and tricellulin) and huge numbers of scaffolding proteins and contribute to the paracellular barrier and fence function. The mutation and deletion of these proteins impair the functions of tight junctions and cause various human diseases. In this paper, we provide an overview of rec...

  2. A Tightly Coupled Non-Equilibrium Magneto-Hydrodynamic Model for Inductively Coupled RF Plasmas

    Science.gov (United States)

    2016-02-29

    Journal Article 3. DATES COVERED (From - To) 12 May 2015 – 06 Oct 2015 4. TITLE AND SUBTITLE A Tightly Coupled Non- Equilibrium Magneto-Hydrodynamic...development a tightly coupled magneto-hydrodynamic model for Inductively Coupled Radio- Frequency (RF) Plasmas. Non Local Thermodynamic Equilibrium (NLTE...effects are described based on a hybrid State-to-State (StS) approach. A multi-temperature formulation is used to account for thermal non- equilibrium

  3. Selective release of the digital extensor hood to reduce intrinsic tightness in tetraplegia

    Science.gov (United States)

    Reinholdt, Carina; Fridén, Jan

    2011-01-01

    Patients with tetraplegia may have various degrees of spasticity in the hand ranging from a completely clenched fist to reduced control of grip at triggered spasticity. The objective of the present study was to evaluate the functional effect of the distal ulnar intrinsic release procedure to reduce intrinsic tightness. Seventeen patients with tetraplegia (37 fingers) and with prominent intrinsic tightness were operated on for distal intrinsic release with a modification of the procedure to include only the ulnar side of the proximal phalanx. All the patients had more pronounced tightness on the ulnar than on the radial side of the affected finger. Long fingers were consistently the most affected digits. The intrinsic tightness was released completely in all patients and the range of motion (ROM) was improved by 25%, and up to 45% in mild and severe cases, respectively. The good immediate effects of treatment as shown by increased ROM remained intact by 6 months postoperatively. These data suggest that the distal ulnar intrinsic release procedure is a simple and valuable way of reducing intrinsic tightness and improving hand function and grip for patients with intrinsic tightness. This procedure can be added to other procedures such as lengthening and transfer of tendons. PMID:21504278

  4. Posterior shoulder tightness and rotator cuff strength assessments in painful shoulders of amateur tennis players

    Directory of Open Access Journals (Sweden)

    Freddy B. Marcondes

    2013-04-01

    Full Text Available BACKGROUND: Previous studies have shown a relationship between shoulder posterior capsule tightness and shoulder pain in overhead athletes. However, this relationship has not been studied in tennis players. OBJECTIVES: Assessment of the shoulder range of motion (ROM, strength and posterior capsule tightness of skilled amateur tennis players who had complaints of dominant shoulder pain in comparison with tennis players without pain. METHOD: Forty-nine skilled amateur tennis players were distributed in 2 groups: Control Group (n=22 and Painful Group (n=27. The first group was composed of asymptomatic subjects, and the second was composed of subjects with shoulder pain on the dominant side. These groups were evaluated to determine the dominant and non-dominant shoulder ROM (internal and external rotation, isometric shoulder strength (internal and external rotation and posterior shoulder tightness by blind evaluators. RESULTS: The ANOVA results indicated significant differences between the groups in the dominant shoulder ROM, posterior capsule tightness, external rotation strength and strength ratio (p<0.05. The intragroup analysis (dominant versus non-dominant in the Painful Group displayed a significant difference for ROM, posterior capsule tightness and external rotation strength (p<0.05. CONCLUSIONS: The tennis players with pain in the dominant shoulder presented greater posterior capsule tightness, internal rotation deficit (ROM, external rotation gain (ROM and deficits in external rotation strength than the tennis players without pain.

  5. Posterior shoulder tightness and rotator cuff strength assessments in painful shoulders of amateur tennis players.

    Science.gov (United States)

    Marcondes, Freddy B; de Jesus, Julio F; Bryk, Flavio F; de Vasconcelos, Rodrigo A; Fukuda, Thiago Y

    2013-01-01

    Previous studies have shown a relationship between shoulder posterior capsule tightness and shoulder pain in overhead athletes. However, this relationship has not been studied in tennis players. Assessment of the shoulder range of motion (ROM), strength and posterior capsule tightness of skilled amateur tennis players who had complaints of dominant shoulder pain in comparison with tennis players without pain. Forty-nine skilled amateur tennis players were distributed in 2 groups: Control Group (n=22) and Painful Group (n=27). The first group was composed of asymptomatic subjects, and the second was composed of subjects with shoulder pain on the dominant side. These groups were evaluated to determine the dominant and non-dominant shoulder ROM (internal and external rotation), isometric shoulder strength (internal and external rotation) and posterior shoulder tightness by blind evaluators. The ANOVA results indicated significant differences between the groups in the dominant shoulder ROM, posterior capsule tightness, external rotation strength and strength ratio (pPainful Group displayed a significant difference for ROM, posterior capsule tightness and external rotation strength (ppain in the dominant shoulder presented greater posterior capsule tightness, internal rotation deficit (ROM), external rotation gain (ROM) and deficits in external rotation strength than the tennis players without pain.

  6. Adaptive tight frame based medical image reconstruction: a proof-of-concept study for computed tomography

    International Nuclear Information System (INIS)

    Zhou, Weifeng; Cai, Jian-Feng; Gao, Hao

    2013-01-01

    A popular approach for medical image reconstruction has been through the sparsity regularization, assuming the targeted image can be well approximated by sparse coefficients under some properly designed system. The wavelet tight frame is such a widely used system due to its capability for sparsely approximating piecewise-smooth functions, such as medical images. However, using a fixed system may not always be optimal for reconstructing a variety of diversified images. Recently, the method based on the adaptive over-complete dictionary that is specific to structures of the targeted images has demonstrated its superiority for image processing. This work is to develop the adaptive wavelet tight frame method image reconstruction. The proposed scheme first constructs the adaptive wavelet tight frame that is task specific, and then reconstructs the image of interest by solving an l 1 -regularized minimization problem using the constructed adaptive tight frame system. The proof-of-concept study is performed for computed tomography (CT), and the simulation results suggest that the adaptive tight frame method improves the reconstructed CT image quality from the traditional tight frame method. (paper)

  7. Active stretching for lower extremity muscle tightness in pediatric patients with lumbar spondylolysis.

    Science.gov (United States)

    Sato, Masahiro; Mase, Yasuyoshi; Sairyo, Koichi

    2017-01-01

    It was reported that hamstring muscle tightness may increase mechanical loading on the lumbar spine. Therefore, we attempt to decrease tightness in the leg muscles in pediatric patients. Forty-six pediatric patients with spondylolysis underwent rehabilitation. We applied active stretching to the hamstrings, quadriceps, and triceps surae. Tightness in each muscle was graded as good, fair, or poor. We educated each patient on how to perform active stretching at home. They were re-evaluated for muscle tightness 2 months later. Tightness at baseline and after 2 months was as follows: for the hamstrings, good in 3 patients, fair in 9, and poor in 34 and significant improved after 2 months (p<0.05), with improvement by least 1 grade seen in 86% of patients with fair or poor at baseline; for the quadriceps, 7, 3, and 30 patients had good, fair and poor, with significant improvements in 72% (p<0.05). For the triceps surae, 6, 3 and 10 patients had good, fair and poor, which improved significantly (p<0.05). Home-based active stretching was effective for relieving muscle tightness in the leg in a pediatric population. Adolescent athletes should perform such exercise to maintain flexibility and prevent lumbar disorders. J. Med. Invest. 64: 136-139, February, 2017.

  8. Effects of posterior capsule tightness on subacromial contact behavior during shoulder motions.

    Science.gov (United States)

    Muraki, Takayuki; Yamamoto, Nobuyuki; Zhao, Kristin D; Sperling, John W; Steinmann, Scott P; Cofield, Robert H; An, Kai-Nan

    2012-09-01

    Although posterior capsule tightness is believed to cause abnormal contact in the subacromial space, it is not clear whether this tightness changes the contact between the acromion and humeral head. Nine fresh, frozen cadaveric shoulders were used to measure contact pressure on the coracoacromial arch during passive flexion, abduction, and internal and external rotation at 90° of elevation in the scapular plane, as well as horizontal adduction and abduction. The site where the peak contact pressure occurred was also observed. The posterior capsule in the region from 8 to 10 o'clock in the right shoulder was plicated to simulate posterior capsule tightness. Peak contact pressure significantly increased with the tightened posterior capsule during flexion. Although peak contact pressure on the coracoacromial ligament during internal rotation significantly increased after capsule tightening, there was no significant increase in pressure when considering the entire coracoacromial arch. The angle where the peak contact pressure occurred during flexion was not significantly far from the end range. The site of the peak contact pressure in 7 of 9 shoulders was on the lesser tuberosity during flexion, regardless of the posterior capsule tightness. Posterior capsule tightness increased contact pressure mainly on the lesser tuberosity during flexion. The peak contact pressure occurred close to the end range of flexion, mainly on the lesser tuberosity. These findings are useful to understand the contribution of posterior capsule tightness to subacromial contact. Copyright © 2012 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Mosby, Inc. All rights reserved.

  9. Performance Improvement of Receivers Based on Ultra-Tight Integration in GNSS-Challenged Environments

    Directory of Open Access Journals (Sweden)

    Feng Qin

    2013-12-01

    Full Text Available Ultra-tight integration was first proposed by Abbott in 2003 with the purpose of integrating a global navigation satellite system (GNSS and an inertial navigation system (INS. This technology can improve the tracking performances of a receiver by reconfiguring the tracking loops in GNSS-challenged environments. In this paper, the models of all error sources known to date in the phase lock loops (PLLs of a standard receiver and an ultra-tightly integrated GNSS/INS receiver are built, respectively. Based on these models, the tracking performances of the two receivers are compared to verify the improvement due to the ultra-tight integration. Meanwhile, the PLL error distributions of the two receivers are also depicted to analyze the error changes of the tracking loops. These results show that the tracking error is significantly reduced in the ultra-tightly integrated GNSS/INS receiver since the receiver’s dynamics are estimated and compensated by an INS. Moreover, the mathematical relationship between the tracking performances of the ultra-tightly integrated GNSS/INS receiver and the quality of the selected inertial measurement unit (IMU is derived from the error models and proved by the error comparisons of four ultra-tightly integrated GNSS/INS receivers aided by different grade IMUs.

  10. Performance Improvement of Receivers Based on Ultra-Tight Integration in GNSS-Challenged Environments

    Science.gov (United States)

    Qin, Feng; Zhan, Xingqun; Du, Gang

    2013-01-01

    Ultra-tight integration was first proposed by Abbott in 2003 with the purpose of integrating a global navigation satellite system (GNSS) and an inertial navigation system (INS). This technology can improve the tracking performances of a receiver by reconfiguring the tracking loops in GNSS-challenged environments. In this paper, the models of all error sources known to date in the phase lock loops (PLLs) of a standard receiver and an ultra-tightly integrated GNSS/INS receiver are built, respectively. Based on these models, the tracking performances of the two receivers are compared to verify the improvement due to the ultra-tight integration. Meanwhile, the PLL error distributions of the two receivers are also depicted to analyze the error changes of the tracking loops. These results show that the tracking error is significantly reduced in the ultra-tightly integrated GNSS/INS receiver since the receiver's dynamics are estimated and compensated by an INS. Moreover, the mathematical relationship between the tracking performances of the ultra-tightly integrated GNSS/INS receiver and the quality of the selected inertial measurement unit (IMU) is derived from the error models and proved by the error comparisons of four ultra-tightly integrated GNSS/INS receivers aided by different grade IMUs.

  11. Sparsity-aware tight frame learning with adaptive subspace recognition for multiple fault diagnosis

    Science.gov (United States)

    Zhang, Han; Chen, Xuefeng; Du, Zhaohui; Yang, Boyuan

    2017-09-01

    It is a challenging problem to design excellent dictionaries to sparsely represent diverse fault information and simultaneously discriminate different fault sources. Therefore, this paper describes and analyzes a novel multiple feature recognition framework which incorporates the tight frame learning technique with an adaptive subspace recognition strategy. The proposed framework consists of four stages. Firstly, by introducing the tight frame constraint into the popular dictionary learning model, the proposed tight frame learning model could be formulated as a nonconvex optimization problem which can be solved by alternatively implementing hard thresholding operation and singular value decomposition. Secondly, the noises are effectively eliminated through transform sparse coding techniques. Thirdly, the denoised signal is decoupled into discriminative feature subspaces by each tight frame filter. Finally, in guidance of elaborately designed fault related sensitive indexes, latent fault feature subspaces can be adaptively recognized and multiple faults are diagnosed simultaneously. Extensive numerical experiments are sequently implemented to investigate the sparsifying capability of the learned tight frame as well as its comprehensive denoising performance. Most importantly, the feasibility and superiority of the proposed framework is verified through performing multiple fault diagnosis of motor bearings. Compared with the state-of-the-art fault detection techniques, some important advantages have been observed: firstly, the proposed framework incorporates the physical prior with the data-driven strategy and naturally multiple fault feature with similar oscillation morphology can be adaptively decoupled. Secondly, the tight frame dictionary directly learned from the noisy observation can significantly promote the sparsity of fault features compared to analytical tight frames. Thirdly, a satisfactory complete signal space description property is guaranteed and thus

  12. Geochemical characteristics of crude oil from a tight oil reservoir in the Lucaogou Formation, Jimusar Sag, Junggar Basin

    Science.gov (United States)

    Cao, Z.

    2015-12-01

    Jimusar Sag, which lies in the Junggar Basin,is one of the most typical tight oil study areas in China. However, the properties and origin of the crude oil and the geochemical characteristics of the tight oil from the Lucaogou Formation have not yet been studied. In the present study, 23 crude oilsfrom the Lucaogou Formation were collected for analysis, such as physical properties, bulk composition, saturated hydrocarbon gas chromatography-mass spectrometry (GC-MS), and the calculation of various biomarker parameters. In addition,source rock evaluation and porosity permeability analysis were applied to the mudstones and siltstones. Biomarkers of suitable source rocks (TOC>1, S1+S2>6mg/g, 0.7%

  13. Lithofacies paleogeography mapping and reservoir prediction in tight sandstone strata: A case study from central Sichuan Basin, China

    Directory of Open Access Journals (Sweden)

    Yuan Zhong

    2017-09-01

    Full Text Available Sand-rich tight sandstone reservoirs are potential areas for oil and gas exploration. However, the high ratio of sandstone thickness to that of the strata in the formation poses many challenges and uncertainties to traditional lithofacies paleogeography mapping. Therefore, the prediction of reservoir sweet spots has remained problematic in the field of petroleum exploration. This study provides new insight into resolving this problem, based on the analyses of depositional characteristics of a typical modern sand-rich formation in a shallow braided river delta of the central Sichuan Basin, China. The varieties of sand-rich strata in the braided river delta environment include primary braided channels, secondary distributary channels and the distribution of sediments is controlled by the successive superposed strata deposited in paleogeomorphic valleys. The primary distributary channels have stronger hydrodynamic forces with higher proportions of coarse sand deposits than the secondary distributary channels. Therefore, lithofacies paleogeography mapping is controlled by the geomorphology, valley locations, and the migration of channels. We reconstructed the paleogeomorphology and valley systems that existed prior to the deposition of the Xujiahe Formation. Following this, rock-electro identification model for coarse skeletal sand bodies was constructed based on coring data. The results suggest that skeletal sand bodies in primary distributary channels occur mainly in the valleys and low-lying areas, whereas secondary distributary channels and fine deposits generally occur in the highland areas. The thickness distribution of skeletal sand bodies and lithofacies paleogeography map indicate a positive correlation in primary distributary channels and reservoir thickness. A significant correlation exists between different sedimentary facies and petrophysical properties. In addition, the degree of reservoir development in different sedimentary facies

  14. Gas centrifuge purge method

    International Nuclear Information System (INIS)

    Theurich, G.R.

    1976-01-01

    A method of separating isotopes in a high speed gas centrifuge is presented. A vertically oriented cylindrical rotor bowl is adapted to rotate about its axis within an evacuated chamber, and an annular molecular pump having an intake end and a discharge end encircles the uppermost portion of the rotor bowl. The molecular pump is attached along its periphery in a leak-tight manner to the evacuated chamber. End cap closure means are affixed to the upper end of the rotor bowl, and a process gas withdrawal and insertion system enters the bowl through the end cap closure means. The evacuated chamber, molecular pump, and end cap define an upper zone at the discharge end of the molecular pump, and the evacuated chamber, molecular pump, and rotor bowl define a lower annular zone at the intake end of said molecular pump. The method for removing gases from the upper and lower zones during centrifuge operation with a minimum loss of process gas from the rotor bowl is described

  15. Tight junction-associated MARVEL proteins marveld3, tricellulin, and occludin have distinct but overlapping functions.

    Science.gov (United States)

    Raleigh, David R; Marchiando, Amanda M; Zhang, Yong; Shen, Le; Sasaki, Hiroyuki; Wang, Yingmin; Long, Manyuan; Turner, Jerrold R

    2010-04-01

    In vitro studies have demonstrated that occludin and tricellulin are important for tight junction barrier function, but in vivo data suggest that loss of these proteins can be overcome. The presence of a heretofore unknown, yet related, protein could explain these observations. Here, we report marvelD3, a novel tight junction protein that, like occludin and tricellulin, contains a conserved four-transmembrane MARVEL (MAL and related proteins for vesicle trafficking and membrane link) domain. Phylogenetic tree reconstruction; analysis of RNA and protein tissue distribution; immunofluorescent and electron microscopic examination of subcellular localization; characterization of intracellular trafficking, protein interactions, dynamic behavior, and siRNA knockdown effects; and description of remodeling after in vivo immune activation show that marvelD3, occludin, and tricellulin have distinct but overlapping functions at the tight junction. Although marvelD3 is able to partially compensate for occludin or tricellulin loss, it cannot fully restore function. We conclude that marvelD3, occludin, and tricellulin define the tight junction-associated MARVEL protein family. The data further suggest that these proteins are best considered as a group with both redundant and unique contributions to epithelial function and tight junction regulation.

  16. Tightly bound soil water introduces isotopic memory effects on mobile and extractable soil water pools.

    Science.gov (United States)

    Newberry, Sarah L; Prechsl, Ulrich E; Pace, Matthew; Kahmen, Ansgar

    2017-08-01

    Cryogenic vacuum extraction is the well-established method of extracting water from soil for isotopic analyses of waters moving through the soil-plant-atmosphere continuum. We investigate if soils can alter the isotopic composition of water through isotope memory effects, and determined which mechanisms are responsible for it. Soils with differing physicochemical properties were re-wetted with reference water and subsequently extracted by cryogenic water distillation. Results suggest some reference waters bind tightly to the soil and not all of this tightly bound water is removed during cryogenic vacuum extraction. Kinetic isotopic fractionation occurring when reference water binds to the soil is likely responsible for the 18 O-depletion of re-extracted reference water, suggesting an enrichment of the tightly bound soil water pool. Further re-wetting of cryogenically extracted soils indicates an isotopic memory effect of tightly bound soil water on water added to the soil. The data suggest tightly bound soil water can influence the isotopic composition of mobile soil water. Findings show that soils influence the isotope composition of soil water by (i) kinetic fractionation when water is bound to the soil and (ii) equilibrium fractionation between different soil water pools. These findings could be relevant for plant water uptake investigations and complicate ecohydrological and paleohydrological studies.

  17. Gas Sensor

    KAUST Repository

    Luebke, Ryan

    2015-01-22

    A gas sensor using a metal organic framework material can be fully integrated with related circuitry on a single substrate. In an on-chip application, the gas sensor can result in an area-efficient fully integrated gas sensor solution. In one aspect, a gas sensor can include a first gas sensing region including a first pair of electrodes, and a first gas sensitive material proximate to the first pair of electrodes, wherein the first gas sensitive material includes a first metal organic framework material.

  18. LDA+U and tight-binding electronic structure of InN nanowires

    Science.gov (United States)

    Molina-Sánchez, A.; García-Cristóbal, A.; Cantarero, A.; Terentjevs, A.; Cicero, G.

    2010-10-01

    In this paper we employ a combined ab initio and tight-binding approach to obtain the electronic and optical properties of hydrogenated Indium nitride (InN) nanowires. We first discuss InN band structure for the wurtzite structure calculated at the LDA+U level and use this information to extract the parameters needed for an empirical tight-binging implementation. These parameters are then employed to calculate the electronic and optical properties of InN nanowires in a diameter range that would not be affordable by ab initio techniques. The reliability of the large nanowires results is assessed by explicitly comparing the electronic structure of a small diameter wire studied both at LDA+U and tight-binding level.

  19. A tight binding and [Formula: see text] study of monolayer stanene.

    Science.gov (United States)

    Jiang, Liming; Marconcini, Paolo; Hossian, Md Sharafat; Qiu, Wanzhi; Evans, Robin; Macucci, Massimo; Skafidas, Efstratios

    2017-09-21

    Stanene is a single layer of tin atoms which has been discovered as an emerging material for quantum spin Hall related applications. In this paper, we present an accurate tight-binding model for single layer stanene near the Fermi level. We parameterized the onsite and hopping energies for the nearest, second nearest, and third nearest neighbor tight-binding method, both without and with spin orbital coupling. We derived the analytical solution for the [Formula: see text]and [Formula: see text] points and numerically investigated the buckling effect on the material electronic properties. In these points of the reciprocal space, we also discuss a corresponding [Formula: see text] description, obtaining the value of the [Formula: see text] parameters both analytically from the tight-binding ones, and numerically, fitting the ab-initio dispersion relations. Our models provide a foundation for large scale atomistic device transport calculations.

  20. Crystal structure of a claudin provides insight into the architecture of tight junctions.

    Science.gov (United States)

    Suzuki, Hiroshi; Nishizawa, Tomohiro; Tani, Kazutoshi; Yamazaki, Yuji; Tamura, Atsushi; Ishitani, Ryuichiro; Dohmae, Naoshi; Tsukita, Sachiko; Nureki, Osamu; Fujiyoshi, Yoshinori

    2014-04-18

    Tight junctions are cell-cell adhesion structures in epithelial cell sheets that surround organ compartments in multicellular organisms and regulate the permeation of ions through the intercellular space. Claudins are the major constituents of tight junctions and form strands that mediate cell adhesion and function as paracellular barriers. We report the structure of mammalian claudin-15 at a resolution of 2.4 angstroms. The structure reveals a characteristic β-sheet fold comprising two extracellular segments, which is anchored to a transmembrane four-helix bundle by a consensus motif. Our analyses suggest potential paracellular pathways with distinctive charges on the extracellular surface, providing insight into the molecular basis of ion homeostasis across tight junctions.

  1. Modulation of Tight Junction Structure and Function by Kinases and Phosphatases Targeting Occludin

    Directory of Open Access Journals (Sweden)

    Max Johannes Dörfel

    2012-01-01

    Full Text Available Tight junctions (TJs typically represent the most apical contacts in epithelial and endothelial cell layers where they play an essential role in the separation of extracellular or luminal spaces from underlying tissues in the body. Depending on the protein composition, TJs define the barrier characteristics and in addition maintain cell polarity. Two major families of integral membrane proteins form the typical TJ strand network, the tight junction-associated MARVEL protein (TAMP family members occludin, tricellulin, and MarvelD3 as well as a specific set of claudins. Occludin was the first identified member of these tetraspanins and is now widely accepted as a regulator of TJ assembly and function. Therefore, occludin itself has to be tightly regulated. Phosphorylation of occludin appears to be of central importance in this context. Here we want to summarize current knowledge on the kinases and phosphatases directly modifying occludin, and their role in the regulation of TJ structure, function, and dynamics.

  2. Loose and Tight GNSS/INS Integrations: Comparison of Performance Assessed in Real Urban Scenarios.

    Science.gov (United States)

    Falco, Gianluca; Pini, Marco; Marucco, Gianluca

    2017-01-29

    Global Navigation Satellite Systems (GNSSs) remain the principal mean of positioning in many applications and systems, but in several types of environment, the performance of standalone receivers is degraded. Although many works show the benefits of the integration between GNSS and Inertial Navigation Systems (INSs), tightly-coupled architectures are mainly implemented in professional devices and are based on high-grade Inertial Measurement Units (IMUs). This paper investigates the performance improvements enabled by the tight integration, using low-cost sensors and a mass-market GNSS receiver. Performance is assessed through a series of tests carried out in real urban scenarios and is compared against commercial modules, operating in standalone mode or featuring loosely-coupled integrations. The paper describes the developed tight-integration algorithms with a terse mathematical model and assesses their efficacy from a practical perspective.

  3. Tight Bra in a 34-Year-Old Woman: An Unusual Cause of Mondor's Disease.

    Science.gov (United States)

    Vincenza Polito, Maria; De Cicco, Pierluigi; Apicella, Rosa

    2014-01-01

    Mondor's disease is characterized by thrombophlebitis of the superficial veins of the breast and the chest wall. The list of causes is long. Various types of clothing, mainly tight bras and girdles, have been postulated as causes. We report a case of a 34-year-old woman who referred typical symptoms and signs of Mondor's disease, without other possible risk factors, and showed the cutaneous findings of the tight bra. Therefore, after distinguishing benign causes of Mondor's disease from hidden malignant causes, the clinicians should consider this clinical entity.

  4. An efficient magnetic tight-binding method for transition metals and alloys

    DEFF Research Database (Denmark)

    Barreteau, Cyrille; Spanjaard, Daniel; Desjonquères, Marie-Catherine

    2016-01-01

    An efficient parameterized self-consistent tight-binding model for transition metals using s, p and d valence atomic orbitals as a basis set is presented. The parameters of our tight-binding model for pure elements are determined from a fit to bulk ab-initio calculations. A very simple procedure...... that does not necessitate any further fitting is proposed to deal with systems made of several chemical elements. This model is extended to spin (and orbital) polarized materials by adding Stoner-like and spin–orbit interactions. Collinear and non-collinear magnetism as well as spin-spirals are considered...

  5. Producing Gas-Oil Ratio Performance of Conventional and Unconventional Reservoirs

    OpenAIRE

    Lei, Guowen

    2012-01-01

    This study presents a detailed analysis of producing gas-oil ratio performance characteristics from conventional reservoir to unconventional reservoir. Numerical simulations of various reservoir fluid systems are included for comparison. In a wide sense of the word, the term of unconventional reservoir is including tight gas sand, coal bed methane, gas hydrate deposits, heavy oil gas shale and etc. In this study we specify the unconventional reservoir to only mean the low and ultra low permea...

  6. Tight Turns

    Directory of Open Access Journals (Sweden)

    Jenifer Sutherland

    2013-01-01

    Full Text Available The plain text was task-oriented in a roundabout way, providing detailed instructions for how NOT to build an elaborate sequence of bridges, each one bound to produce, according to chapters one through twenty-three, disastrous results. Graphic novels disguised as illuminated letters twisted the tent-dwelling decipherer into painful self-recognition. The flashlight followed the phases of the moon. Meanwhile one strand of marginalia, written in anxious back-slant, pleaded for some kind of adjustable form for managing the confluence, especially during flood season. I like what we came up with. 'We' is a little big word. In fact the tent turns out to be one of those Borgesian core-tech structures allowing for astonishing internal expansion. There's not much we didn't get in there and not much in there that didn't get us. So I suppose that's it. This tent. This confluence. These children who found me here, turned text into life and made life home.

  7. AUV Positioning Method Based on Tightly Coupled SINS/LBL for Underwater Acoustic Multipath Propagation

    Directory of Open Access Journals (Sweden)

    Tao Zhang

    2016-03-01

    Full Text Available This paper researches an AUV (Autonomous Underwater Vehicle positioning method based on SINS (Strapdown Inertial Navigation System/LBL (Long Base Line tightly coupled algorithm. This algorithm mainly includes SINS-assisted searching method of optimum slant-range of underwater acoustic propagation multipath, SINS/LBL tightly coupled model and multi-sensor information fusion algorithm. Fuzzy correlation peak problem of underwater LBL acoustic propagation multipath could be solved based on SINS positional information, thus improving LBL positional accuracy. Moreover, introduction of SINS-centered LBL locating information could compensate accumulative AUV position error effectively and regularly. Compared to loosely coupled algorithm, this tightly coupled algorithm can still provide accurate location information when there are fewer than four available hydrophones (or within the signal receiving range. Therefore, effective positional calibration area of tightly coupled system based on LBL array is wider and has higher reliability and fault tolerance than loosely coupled. It is more applicable to AUV positioning based on SINS/LBL.

  8. Loose and Tight Coupling in Educational Organizations--An Integrative Literature Review

    Science.gov (United States)

    Hautala, Tanja; Helander, Jaakko; Korhonen, Vesa

    2018-01-01

    Purpose: The purpose of this paper is to review and synthesize the attributes of loose and tight coupling in educational organizations. In addition, it is aimed to determine whether this phenomenon has value and strategies to offer for the current educational administration and research. Design/methodology/approach: Integrative literature review…

  9. Detection and repositioning of tight fighting annulus spacers in CANDU® fuel channels

    Energy Technology Data Exchange (ETDEWEB)

    Hersak, G.; Kittmer, A. [Atomic Energy of Canada Limited, Chalk River, Ontario (Canada); Goszczynski, J. [Candu Energy Inc., Mississauga, Ontario (Canada); Kazimer, D. [Bruce Power, Tiverton, Ontario (Canada)

    2014-06-15

    The latest generation of CANDU® reactors has been constructed with tight-fitting annulus spacers to maintain the annular gap between the inner pressure tubes and the outer calandria tubes. These spacers cannot be detected and repositioned with the existing Spacer Location and Repositioning (SLAR) process, which is designed to work with loose-fitting annulus spacers. There is currently no established technology to detect and reposition tight-fitting annulus spacers. Atomic Energy of Canada Limited has been performing research and development to locate and move tight-fitting annulus spacers using Modal Detection and Repositioning (MODAR) technology since 2005 and is currently working in collaboration with Candu Energy and Bruce Power on a production system to be deployed for an In-reactor demonstration in the next year. The MODAR technology uses controlled vibrations on a short, isolated length of pressure tube to locate and reposition tight-fitting annulus spacers. MODAR technology will allow the utilities to demonstrate fuel channel integrity to the regulator and obtain approval for additional years of reactor operation. This paper briefly describes the technology and provides an overview of the tool testing and development. (author)

  10. Evaluation of proximal contact tightness of Class II resin composite restorations.

    NARCIS (Netherlands)

    Saber, M.H.; Loomans, B.A.C.; Zohairy, A. El; Dorfer, C.E.; El-Badrawy, W.

    2010-01-01

    OBJECTIVE: The objective of the current study was to compare in-vitro the proximal contact tightness (PCT) of Class II resin composite restorations (RCR) placed with different established and new placement techniques. METHODS: 105 ivorine lower left first molars with standardized MO cavities were

  11. Active Wheatstone Bridge — A solution of tight speed dc motor control

    African Journals Online (AJOL)

    Very tight control of the speed of a d.c. motor drive may be achieved by incorporating the machine within a closed loop system. The employed feedback signal is proportional to the motor speed for comparison against a reference quantity. For armature-controlled d.c. motors the difference or error signal provides appropriate ...

  12. Vibrationally resolved UV/Vis spectroscopy with time-dependent density functional based tight binding

    NARCIS (Netherlands)

    Ruger, R.; Niehaus, T.; van Lenthe, E.; Heine, T.; Visscher, L.

    2016-01-01

    We report a time-dependent density functional based tight-binding (TD-DFTB) scheme for the calculation of UV/Vis spectra, explicitly taking into account the excitation of nuclear vibrations via the adiabatic Hessian Franck-Condon method with a harmonic approximation for the nu- clear wavefunction.

  13. Integration of integrity constraints in federated schemata based on tight constraining

    NARCIS (Netherlands)

    Balsters, H; de Brock, EO; Meersman, R; Tari, Z; VanderAalst, W; Bussler, C; Gal, A; Cahill,; Vinoski, S; Vogels, W; Gatarci, T; Sycara, K

    2004-01-01

    A database federation provides for tight coupling of a collection of heterogeneous legacy databases into a global integrated system. A large problem regarding information quality in database federations concerns achieving and maintaining consistency of the data on the global level of the federation.

  14. Quantum confined Stark effect in Gaussian quantum wells: A tight-binding study

    Energy Technology Data Exchange (ETDEWEB)

    Ramírez-Morales, A.; Martínez-Orozco, J. C.; Rodríguez-Vargas, I. [Unidad Académica de Física, Universidad Autónoma de Zacatecas, Calzada Solidaridad Esquina Con Paseo La Bufa S/N, 98060 Zacatecas, Zac. (Mexico)

    2014-05-15

    The main characteristics of the quantum confined Stark effect (QCSE) are studied theoretically in quantum wells of Gaussian profile. The semi-empirical tight-binding model and the Green function formalism are applied in the numerical calculations. A comparison of the QCSE in quantum wells with different kinds of confining potential is presented.

  15. Bose-Einstein condensation in a tightly confining dc magnetic trap

    NARCIS (Netherlands)

    Mewes, M.O.; Andrews, M.R.; van Druten, N.J.; Kurn, D.M.; Durfee, D.S.; Ketterle, W.

    1996-01-01

    Bose-Einstein condensation of sodium atoms has been observed in a novel "cloverleaf" trap. This trap combines tight confinement with excellent optical access, using only dc electromagnets. Evaporative cooling in this trap produced condensates of 5 x 10/6 atoms, a tenfold improvement over previous

  16. Dual-functionalized PAMAM dendrimers with improved P-glycoprotein inhibition and tight junction modulating effect.

    Science.gov (United States)

    Liu, Yuanjie; Chiu, Gigi N C

    2013-12-09

    This study aims to surface modify poly(amido amine) or PAMAM dendrimers by sequentially grafting poly(ethylene glycol) or PEG and 4-thiobutylamidine (TBA) so as to reduce PAMAM cytotoxicity while improving the ability of PAMAM to modulate P-glycoprotein (P-gp) efflux and tight junction integrity. Conjugation of functional groups was determined by NMR spectroscopy, FT-IR, thiol group quantification and molecular weight estimation. The yield of the dual-functionalized dendrimers was >80%. The dual-functionalized dendrimer could significantly reduce PAMAM cytotoxicity to effect could be affected by the extent of PEGylation of the dendrimer. Surface-modified PAMAM dendrimers, either by single or dual functionalization, could better modulate tight junction integrity in comparison with unmodified PAMAM, as demonstrated through immunostaining of the tight junction marker ZO-1, permeation of the model compound Lucifer Yellow (LY) and transepithelial electrical resistance (TEER). Of importance, reversible tight junction modulating effect was only observed in the dual-functionalized dendrimers. Collectively, dual functionalization with PEG and TBA represented a promising approach in altering PAMAM dendrimer surface for potential application in oral drug delivery.

  17. Microwave emulations and tight-binding calculations of transport in polyacetylene

    Energy Technology Data Exchange (ETDEWEB)

    Stegmann, Thomas, E-mail: stegmann@icf.unam.mx [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Franco-Villafañe, John A., E-mail: jofravil@fis.unam.mx [Instituto de Física, Benemérita Universidad Autónoma de Puebla, Apartado Postal J-48, 72570 Puebla (Mexico); Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Ortiz, Yenni P. [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Kuhl, Ulrich [Université de Nice – Sophia Antipolis, Laboratoire de la Physique de la Matière Condensée, CNRS, Parc Valrose, 06108 Nice (France); Mortessagne, Fabrice, E-mail: fabrice.mortessagne@unice.fr [Université de Nice – Sophia Antipolis, Laboratoire de la Physique de la Matière Condensée, CNRS, Parc Valrose, 06108 Nice (France); Seligman, Thomas H. [Instituto de Ciencias Físicas, Universidad Nacional Autónoma de México, Avenida Universidad s/n, 62210 Cuernavaca (Mexico); Centro Internacional de Ciencias, 62210 Cuernavaca (Mexico)

    2017-01-05

    A novel approach to investigate the electron transport of cis- and trans-polyacetylene chains in the single-electron approximation is presented by using microwave emulation measurements and tight-binding calculations. In the emulation we take into account the different electronic couplings due to the double bonds leading to coupled dimer chains. The relative coupling constants are adjusted by DFT calculations. For sufficiently long chains a transport band gap is observed if the double bonds are present, whereas for identical couplings no band gap opens. The band gap can be observed also in relatively short chains, if additional edge atoms are absent, which cause strong resonance peaks within the band gap. The experimental results are in agreement with our tight-binding calculations using the nonequilibrium Green's function method. The tight-binding calculations show that it is crucial to include third nearest neighbor couplings to obtain the gap in the cis-polyacetylene. - Highlights: • Electronic transport in individual polyacetylene chains is studied. • Microwave emulation experiments and tight-binding calculations agree well. • In long chains a band-gap opens due the dimerization of the chain. • In short chains edge atoms cause strong resonance peaks in the center of the band-gap.

  18. Nonlinear Filtering with IMM Algorithm for Ultra-Tight GPS/INS Integration

    Directory of Open Access Journals (Sweden)

    Dah-Jing Jwo

    2013-05-01

    Full Text Available Abstract This paper conducts a performance evaluation for the ultra-tight integration of a Global positioning system (GPS and an inertial navigation system (INS, using nonlinear filtering approaches with an interacting multiple model (IMM algorithm. An ultra-tight GPS/INS architecture involves the integration of in-phase and quadrature components from the correlator of a GPS receiver with INS data. An unscented Kalman filter (UKF, which employs a set of sigma points by deterministic sampling, avoids the error caused by linearization as in an extended Kalman filter (EKF. Based on the filter structural adaptation for describing various dynamic behaviours, the IMM nonlinear filtering provides an alternative for designing the adaptive filter in the ultra-tight GPS/INS integration. The use of IMM enables tuning of an appropriate value for the process of noise covariance so as to maintain good estimation accuracy and tracking capability. Two examples are provided to illustrate the effectiveness of the design and demonstrate the effective improvement in navigation estimation accuracy. A performance comparison among various filtering methods for ultra-tight integration of GPS and INS is also presented. The IMM based nonlinear filtering approach demonstrates the effectiveness of the algorithm for improved positioning performance.

  19. MRI tight posterior fossa sign for prenatal diagnosis of Chiari type II malformation

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Kumiko; Ishikura, Reiichi; Ogawa, Masayo; Takada, Yoshihiro; Yamamoto, Satoshi; Fujiwara, Masayuki; Hirota, Shozo [Hyogo College of Medicine, Department of Radiology, Nishinomiya, Hyogo (Japan); Shakudo, Miyuki [Osaka City General Hospital, Department of Radiology, Osaka (Japan); Tanaka, Hiroyuki [Hyogo College of Medicine, Department of Gynecology, Nishinomiya (Japan); Minagawa, Kyoko [Hyogo College of Medicine, Department of Pediatrics, Nishinomiya (Japan)

    2007-12-15

    Chiari type II malformation (CMII) is one of three hindbrain malformations that display hydrocephalus. We have observed that cerebrospinal fluid (CSF) signal in the posterior fossa, which is always apparent on normal fetal MR images, is not visible in a fetus with CMII. We use the term 'tight posterior fossa' for this MR imaging finding, and evaluate the diagnostic value of this finding on fetal MR images. Included in the study were 21 fetuses which underwent brain MR imaging at 1.5 T using two-dimensional balanced turbo-field-echo (2-D balanced-TFE) in the axial and sagittal planes. Postnatal diagnoses were CMII (n=5), CNS abnormalities other than CMII (n=8), and no abnormality (n=8). A tight posterior fossa was defined as an absent or slit-like water signal space around the hindbrain in the posterior fossa on both sagittal and axial MR images. All CMII fetuses displayed a tight posterior fossa on MR images. Hydrocephalus was visualized in all CMII fetuses and myelomeningocele in four fetuses, but hindbrain herniation was visualized only in two of five fetuses. The CSF signal surrounding the hindbrain was clearly visible in all the other 16 fetuses, including five with hydrocephalus not associated with CMII, although it was slightly narrower in a fetus with a cloverleaf skull than in the normal fetuses. Tight posterior fossa in the presence of hydrocephalus is a useful and characteristic finding of CMII on fetal MRI. (orig.)

  20. Third nearest neighbor parameterized tight binding model for graphene nano-ribbons

    Directory of Open Access Journals (Sweden)

    Van-Truong Tran

    2017-07-01

    Full Text Available The existing tight binding models can very well reproduce the ab initio band structure of a 2D graphene sheet. For graphene nano-ribbons (GNRs, the current sets of tight binding parameters can successfully describe the semi-conducting behavior of all armchair GNRs. However, they are still failing in reproducing accurately the slope of the bands that is directly associated with the group velocity and the effective mass of electrons. In this work, both density functional theory and tight binding calculations were performed and a new set of tight binding parameters up to the third nearest neighbors including overlap terms is introduced. The results obtained with this model offer excellent agreement with the predictions of the density functional theory in most cases of ribbon structures, even in the high-energy region. Moreover, this set can induce electron-hole asymmetry as manifested in results from density functional theory. Relevant outcomes are also achieved for armchair ribbons of various widths as well as for zigzag structures, thus opening a route for multi-scale atomistic simulation of large systems that cannot be considered using density functional theory.

  1. Microscopic surface wettability electrochemical characterization of tight sandstone with infrared spectra testing

    Science.gov (United States)

    Song, L.; Ning, Z. F.; Li, N.; Zhang, B.; Ding, G. Y.

    2017-08-01

    The distribution of charge density on the surface of microscopic tight oil is studied by using Stern double electric layer theory, and the mathematical flow model of polar fluid with micro powers in tight oil reservoir is established. The Fourier transform infrared (FTIR) were used to investigate the interaction of rock surface functional groups with fluids. The results show that: (1) When the external fluid of the polar group passes through the dense micro-nano pore, it will form an electric double layer on the surface of the rock, there will be a certain thickness of the liquid membrane, the fluid migration has a certain Of the electrical viscosity effect, will have a certain flow resistance. (2) The Fourier transform infrared spectroscopy of the Chang 7 tight reservoir rock samples exists and distributes different kinds of peaks. The left peak trend determines the presence of hydroxyl groups. The four fronts and types of the right side can be used to obtain that calcium carbonate CO3 2- exists. (3) There are CO3 2- and hydroxyl functional minerals in the Chang 7 tight sandstone samples. It is consistent with the basic mineral analysis measured by X-ray diffraction. When the external fluid affects the rock surface, the surface will occur in the physical van der Waals force and chemical bond interaction, so it will affect the flow of water on the surface.

  2. Third nearest neighbor parameterized tight binding model for graphene nano-ribbons

    Science.gov (United States)

    Tran, Van-Truong; Saint-Martin, Jérôme; Dollfus, Philippe; Volz, Sebastian

    2017-07-01

    The existing tight binding models can very well reproduce the ab initio band structure of a 2D graphene sheet. For graphene nano-ribbons (GNRs), the current sets of tight binding parameters can successfully describe the semi-conducting behavior of all armchair GNRs. However, they are still failing in reproducing accurately the slope of the bands that is directly associated with the group velocity and the effective mass of electrons. In this work, both density functional theory and tight binding calculations were performed and a new set of tight binding parameters up to the third nearest neighbors including overlap terms is introduced. The results obtained with this model offer excellent agreement with the predictions of the density functional theory in most cases of ribbon structures, even in the high-energy region. Moreover, this set can induce electron-hole asymmetry as manifested in results from density functional theory. Relevant outcomes are also achieved for armchair ribbons of various widths as well as for zigzag structures, thus opening a route for multi-scale atomistic simulation of large systems that cannot be considered using density functional theory.

  3. Oxytocin injections in the postpartal period affect mammary tight junctions in sows

    DEFF Research Database (Denmark)

    Farmer, C.; Lessard, M.; Knight, C. H.

    2017-01-01

    The potential impacts of injecting oxytocin (OXY) to sows in the early postpartum period on the quality of mammary tight junctions, milk composition, and immune status of sows and piglets were studied. Postparturient sows received i.m. injections of either saline (control [CTL]; n = 10) or 75 IU ...

  4. Gas gangrene

    Science.gov (United States)

    Tissue infection - Clostridial; Gangrene - gas; Myonecrosis; Clostridial infection of tissues; Necrotizing soft tissue infection ... Gas gangrene is most often caused by bacteria called Clostridium perfringens. It also can be caused by ...

  5. Gas separating

    Science.gov (United States)

    Gollan, Arye Z.

    1990-12-25

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing.

  6. Glovebox with purification and pressure control of the neutral gas atmosphere in closed circuit

    International Nuclear Information System (INIS)

    Cadrot, J.

    1990-01-01

    In the gas main are placed 2 series of specific gas purifiers in parallel. Pressure is controlled with a buffer tank two three way solenoid value upstream and down stream a compressor and a supercharger. A checking board allows continuous monitoring of circuit tightness [fr

  7. Leak tight sealants and joint details for concrete structure in RAPP

    International Nuclear Information System (INIS)

    Singha Roy, P.K.; Baste, M.S.

    1975-01-01

    Leak tightness may pertain to either air or water and in extreme cases each will require separate consideration based on general basic requirements. Leak-tight sealants against air pressure are required in the construction joints and around penetrations in the concrete containment structures. The containment structures should be able to withstand the maximum anticipated design pressure during the incident of a MCA with only minimal leakage (0.1% of bldg. volume per day in RAPP) which is mostly through these joints. Apart from proper joint design and preparation the sealant itself must have superb adhesion to the concrete surface and integrify throughout its service life to prevent any rupture or micro-cracks at any section of the joint. Leak tightness pertains to water tightness as well. A critical water-tight joint at the bottom dome of the prestressed concrete dousing tank at its junction with the 36 inches dia dousing water pipes constructed in RAPP-2, which should be able to withstand the water pressure, continuous submergence in the water of the tank and the longitudinal and lateral movement of the water pipes during opening and closure of the dousing valves, has been made and hydrostatically tested when not even the slight sweating was found. The construction and materials of the above joints and the sealant along with the properties and performance observed during testing/use are described. As the sealant used is an imported poly-sulphide caulking compound suggestions have also been made, which may be kept in mind while developing an Indian substitute. (author)

  8. Outcome of tight versus standard glycemic control in coronary artery bypass patients

    International Nuclear Information System (INIS)

    Subhani, H.

    2012-01-01

    Objectives: To compare the outcome of tight versus standard glycemic control and its impact on post operative morbidity and short term mortality in patients undergoing Coronary Artery Bypass Grafting (CA-BG). Patients and Methods: A prospective surveillance of 124 patients undergoing isolated CABG surgery (on pump) was included in the study, 62 patients in each group were randomly assigned to tight and standard glucose control group. The main exposure was insulin in respect to level of blood glucose and the primary outcome measures were Sternotomy wound infection, Leg wound infection and new Myocardial Infarction. Surgical Site infection was assessed on a daily basis during the patient's stay in the Department of Cardio-thoracic Surgery, Sheikh Zayed Hospital, Lahore or within 30 days of operation prompting the patient to return to the hospital. Chi-square test or test was used to identify the significance of various short term morbidities and mortality. Results: In this study, 12 patients in the standard group and 4 patients in the tightly controlled group developed Sternal wound infection (p value 0.046). Similarly, 9 versus 2 patients in the standard and tight group respectively developed Leg wound infection (p-value 0.035). Test of proportion was applied and it was found that there was significant difference in the pro-portion of infection in the two groups (p value 0.05). However, there were no significant differences in other morbidities and the short term mortality. Conclusion: Study confirmed that tight glucose con-trol post operatively in CABG patient's results in reduced sternal and leg wound infection rates; however, there was no effect on other morbidities and short term mortality. (author)

  9. Technical Note. The Concept of a Computer System for Interpretation of Tight Rocks Using X-Ray Computed Tomography Results

    Directory of Open Access Journals (Sweden)

    Habrat Magdalena

    2017-03-01

    Full Text Available The article presents the concept of a computer system for interpreting unconventional oil and gas deposits with the use of X-ray computed tomography results. The functional principles of the solution proposed are presented in the article. The main goal is to design a product which is a complex and useful tool in a form of a specialist computer software for qualitative and quantitative interpretation of images obtained from X-ray computed tomography. It is devoted to the issues of prospecting and identification of unconventional hydrocarbon deposits. The article focuses on the idea of X-ray computed tomography use as a basis for the analysis of tight rocks, considering especially functional principles of the system, which will be developed by the authors. The functional principles include the issues of graphical visualization of rock structure, qualitative and quantitative interpretation of model for visualizing rock samples, interpretation and a description of the parameters within realizing the module of quantitative interpretation.

  10. Use of X-ray computed tomography in core analysis of tight North Sea Chalk. Final report

    Energy Technology Data Exchange (ETDEWEB)

    Mogensen, K.; Stenby, E.H.

    1997-12-01

    This EFP-95 final report summarizes work performed at the Engineering Research Center (IVC-SEP) on the use of CT scanning in core analysis of tight core material from the North Sea. In this work, CT scanning has been applied to chalk material from Danish North Sea oil reservoirs. Results indicate that CT is fast and reliable for prediction of porosity. Typical errors lie within 2-3%. Calculation of fluid saturations requires considerable care from the experimentalists. Saturating a core ought to be performed by pulling vacuum to avoid trapped air bubbles. These bubbles may be produced after subsequent water and gas flooding, thereby ruining the mass balance calculations. Results performed at Stanford University show that if these simple precautions are taken, fluid saturations calculated from CT scanning are generally very accurate. Moreover, it appears that contrast agents need not be added to either phase. Regarding three-phase measurements the results are somewhat disappointing. Previous work using the dual-energy technique has indicated that the accuracy is less than satisfactory, due to an increased noise level at the low-energy setting. More work needs to be done in the future to develop the necessary expertise. The image analysis of the residual oil saturation after a gas flood can be simplified if water is assumed to be immobile during the injection. In that case, the resulting prediction of residual oil saturation is in excellent agreement with measured values. The general conclusion is that CT scanning holds a great potential as an assisting tool in modern core analysis, despite its limitations and the numerous implementation-related problems encountered during this work. (au) EFP-95. 57 refs.

  11. Ruslands Gas

    OpenAIRE

    Elkjær, Jonas Bondegaard

    2008-01-01

    This paper is about Russian natural gas and the possibility for Russia to use its reserves of natural gas politically towards the European Union to obtain some political power. Russia owns 32,1 % of the world gas reserves, and The European Union is getting 50 % of its gas import from Russia. I will use John Mearsheimer’s theory ”The Tragedy of Great Power Politics” to explain how Russia can use its big reserves of gas on The European Union to get political influence. This paper is about Ru...

  12. Ruslands Gas

    OpenAIRE

    Elkjær, Jonas Bondegaard

    2008-01-01

    This paper is about Russian natural gas and the possibility for Russia to use its reserves of natural gas politically towards the European Union to obtain some political power. Russia owns 32,1 % of the world gas reserves, and The European Union is getting 50 % of its gas import from Russia. I will use John Mearsheimer’s theory ”The Tragedy of Great Power Politics” to explain how Russia can use its big reserves of gas on The European Union to get political influence.

  13. Harnessing gas

    International Nuclear Information System (INIS)

    1998-01-01

    Nigeria produces almost two million barrels of oil a day from its oil fields in the Niger Delta area. Most of the oil comes from reservoirs containing gas, which is produced with the oil. This associated gas is separated from the oil at flow stations and more than 95 per cent of it is flared-currently a total of some two billion standard cubic feet per day (scf/d), which is estimated to be about a quarter of the gas the world flares and vents. The energy available from Nigeria's flared gas is prodigious, equivalent to one quarter of France's gas requirements. The company recognises that flaring wastes a valuable resource and is environmentally damaging. It aims to stop necessary flaring as soon as possible through a series of projects to harness or conserve this gas. Several gas gathering and conservation projects are already underway in response to emerging markets while other plans await new markets. The company is committed to reduce gas flaring as soon as is feasible to the minimum needed to maintain safe operations. But why are solutions being found only now? why has Nigeria been flaring gas for so long? These question lie at the crux of the debate about Nigeria and gas flaring and the answers, which continue to have a major impact on associated gas development today, are rooted in history, economics and geography

  14. Daya Bay Antineutrino Detector gas system

    Science.gov (United States)

    Band, H. R.; Cherwinka, J. J.; Chu, M.-C.; Heeger, K. M.; Kwok, M. W.; Shih, K.; Wise, T.; Xiao, Q.

    2012-11-01

    The Daya Bay Antineutrino Detector gas system is designed to protect the liquid scintillator targets of the antineutrino detectors against degradation and contamination from exposure to ambient laboratory air. The gas system is also used to monitor the leak tightness of the antineutrino detector assembly. The cover gas system constantly flushes the gas volumes above the liquid scintillator with dry nitrogen to minimize oxidation of the scintillator over the five year lifetime of the experiment. This constant flush also prevents the infiltration of radon or other contaminants into these detecting liquids keeping the internal backgrounds low. Since the Daya Bay antineutrino detectors are immersed in the large water pools of the muon veto system, other gas volumes are needed to protect vital detector cables or gas lines. These volumes are also purged with dry gas. Return gas is monitored for oxygen content and humidity to provide early warning of potentially damaging leaks. The design and performance of the Daya Bay Antineutrino Detector gas system is described.

  15. Effect of fabric material and tightness on the mechanical properties of fabric–cement composites

    Directory of Open Access Journals (Sweden)

    Magdi El Messiry

    2014-12-01

    Full Text Available This study shows the effect of fabric tightness and fabric material on the mechanical properties of fabric–cement composites. Six fabric designs from the same fabric material were used. These fabric designs are vary in the specific tightness. Also, three fabric materials with the same fabric design were used in this work. Different sets of specimens were made, after that these specimens were tested on tensile and bending testing machines. It was found that the mechanical properties of the composite materials were influenced by the length of the warp thread float, i.e. the longer is the yarns float in the fabric, the greater is the tensile strength properties of the reinforced fabric, its construction and the material of the reinforced fabric. Therefore, it is recommended to use fabric with yarns with higher tenacity in the direction of the application of load and with either long float or minimum number of intersections.

  16. Meralgia paresthetica: a result of tight new trendy low cut trousers ('taille basse').

    Science.gov (United States)

    Moucharafieh, Ramzi; Wehbe, Joseph; Maalouf, Ghassan

    2008-04-01

    Meralgia paresthetica is an entrapment neuropathy involving the lateral femoral cutaneous nerve of the thigh. Patients complain of a persistent burning sensation, tingling and aching pain, and hypersensitivity or hyposensitivity in the anterolateral aspect of the thigh. Numerous direct and indirect causes for the disease have been suggested in the literature. We present 12 cases that were diagnosed to have meralgia paresthetica due to tight new fashion low cut trousers ('taille basse'). The diagnosis was confirmed by injecting a small amount of a short acting local anesthetic around the lateral femoral cutaneous nerve which alleviated the symptoms for several hours. Electrophysiologic studies were sensitive in 83.3% of the cases. All cases were treated successfully using conservative methods, namely avoiding tight trousers, local steroid infiltration and weight reduction.

  17. Transit Duration Variations due to Secular Interactions in Systems with Tightly-packed Inner Planets

    Science.gov (United States)

    Boley, Aaron; Van Laerhoven, Christa; Granados Contreras, A. Paula

    2018-04-01

    Secular interactions among planets in multi-planet systems will lead to variations in orbital inclinations and to the precession of orbital nodes. Taking known system architectures at face value, we calculate orbital precession rates for planets in tightly-packed systems using classical second-order secular theory, in which the orientation of the orbits can be described as a vector sum of eigenmodes and the eigenstructure is determined only by the masses and semi-major axes of the planets. Using this framework, we identify systems that have fast precession frequencies, and use those systems to explore the range of transit duration variation that could occur using amplitudes that are consistent with tightly-packed planetary systems. We then further assess how transit duration variations could be used in practice.

  18. Relevant multi-setting tight Bell inequalities for qubits and qutrits

    International Nuclear Information System (INIS)

    Deng Dongling; Zhou Zisui; Chen Jingling

    2009-01-01

    In the celebrated paper [D. Collins, N. Gisin, J. Phys. A Math. Gen. 37 (2004) 1775], Collins and Gisin presented for the first time a three-setting Bell inequality (here we call it CG inequality for simplicity) which is relevant to the Clauser-Horne-Shimony-Holt (CHSH) inequality. Inspired by their brilliant ideas, we obtained some multi-setting tight Bell inequalities, which are relevant to the CHSH inequality and the CG inequality. Moreover, we generalized the method in the paper [J.L. Chen, D.L. Deng, Phys. Rev. A 79 (2009) 012115] to construct Bell inequality for qubits to higher dimensional system. Based on the generalized method, we present, for the first time, a three-setting tight Bell inequality for two qutrits, which is maximally violated by nonmaximally entangled states and relevant to the Collins-Gisin-Linden-Massar-Popescu inequality.

  19. Concise and tight security analysis of the Bennett–Brassard 1984 protocol with finite key lengths

    International Nuclear Information System (INIS)

    Hayashi, Masahito; Tsurumaru, Toyohiro

    2012-01-01

    We present a tight security analysis of the Bennett–Brassard 1984 protocol taking into account the finite-size effect of key distillation and achieving unconditional security. We begin by presenting a concise analysis utilizing the normal approximation of the hypergeometric function. Next we show that a similar tight bound can also be obtained by a rigorous argument without relying on any approximation. In particular, for the convenience of experimentalists who wish to evaluate the security of their quantum key distribution systems, we also give the explicit procedures of our key distillation and show how to calculate the secret key rate and the security parameter from a given set of experimental parameters. In addition to the exact values of key rates and security parameters, we also describe how to obtain their rough estimates using the normal approximation. (paper)

  20. Tight upper bound for the maximal quantum value of the Svetlichny operators

    Science.gov (United States)

    Li, Ming; Shen, Shuqian; Jing, Naihuan; Fei, Shao-Ming; Li-Jost, Xianqing

    2017-10-01

    It is a challenging task to detect genuine multipartite nonlocality (GMNL). In this paper, the problem is considered via computing the maximal quantum value of Svetlichny operators for three-qubit systems and a tight upper bound is obtained. The constraints on the quantum states for the tightness of the bound are also presented. The approach enables us to give the necessary and sufficient conditions of violating the Svetlichny inequality (SI) for several quantum states, including the white and color noised Greenberger-Horne-Zeilinger (GHZ) states. The relation between the genuine multipartite entanglement concurrence and the maximal quantum value of the Svetlichny operators for mixed GHZ class states is also discussed. As the SI is useful for the investigation of GMNL, our results give an effective and operational method to detect the GMNL for three-qubit mixed states.

  1. Tight junction between endothelial cells: the interaction between nanoparticles and blood vessels

    Directory of Open Access Journals (Sweden)

    Yue Zhang

    2016-05-01

    Full Text Available Since nanoparticles are now widely applied as food additives, in cosmetics and other industries, especially in medical therapy and diagnosis, we ask here whether nanoparticles can cause several adverse effects to human health. In this review, based on research on nanotoxicity, we mainly discuss the negative influence of nanoparticles on blood vessels in several aspects and the potential mechanism for nanoparticles to penetrate endothelial layers of blood vessels, which are the sites of phosphorylation of tight junction proteins (claudins, occludins, and ZO (Zonula occludens proteins, oxidative stress and shear stress. We propose a connection between the presence of nanoparticles and the regulation of the tight junction, which might be the key approach for nanoparticles to penetrate endothelial layers and then have an impact on other tissues and organs.

  2. Headache under simulated microgravity is related to endocrine, fluid distribution, and tight junction changes.

    Science.gov (United States)

    Feuerecker, Matthias; van Oosterhout, Willebrordus P J; Feuerecker, Benedikt; Matzel, Sandra; Schelling, Gustav; Rehm, Markus; Vein, Alla A; Choukèr, Alexander

    2016-05-01

    Head-down-tilted bed rest (HDTBR) induces headaches similar to headaches during space flights. The objective of this investigation was to study hematological, endocrinological, fluid changes and tight junctions in HDTBR-induced headaches as a proxy for space headache. The randomized crossover HDTBR design by the European Space Agency included 12 healthy, nonheadache male subjects. Before, during, and after confined HDTBR periods, epinephrine (urine), cortisol (saliva), hematological, endothelium markers, and fluid distribution parameters were measured. Headaches were assessed with a validated headache questionnaire. Compared with baseline, HDTBR in all subjects was associated with higher hematocrit, hemoglobin, and epinephrine levels, higher erythrocyte counts, and lower relative plasma volumes (all P zonulin was elevated (vs headache-free subjects in HDTBR days 1, 3, 5; P < 0.05). HDTBR induces hemoconcentration and fluid redistribution in all subjects. During headache episodes, endocrinological changes, fluid distribution, and tight junctions were more pronounced, suggesting an additional role in headache pathophysiology.

  3. Effect of tight control management on Crohn's disease (CALM): a multicentre, randomised, controlled phase 3 trial.

    Science.gov (United States)

    Colombel, Jean-Frederic; Panaccione, Remo; Bossuyt, Peter; Lukas, Milan; Baert, Filip; Vaňásek, Tomas; Danalioglu, Ahmet; Novacek, Gottfried; Armuzzi, Alessandro; Hébuterne, Xavier; Travis, Simon; Danese, Silvio; Reinisch, Walter; Sandborn, William J; Rutgeerts, Paul; Hommes, Daniel; Schreiber, Stefan; Neimark, Ezequiel; Huang, Bidan; Zhou, Qian; Mendez, Paloma; Petersson, Joel; Wallace, Kori; Robinson, Anne M; Thakkar, Roopal B; D'Haens, Geert

    2018-12-23

    Biomarkers of intestinal inflammation, such as faecal calprotectin and C-reactive protein, have been recommended for monitoring patients with Crohn's disease, but whether their use in treatment decisions improves outcomes is unknown. We aimed to compare endoscopic and clinical outcomes in patients with moderate to severe Crohn's disease who were managed with a tight control algorithm, using clinical symptoms and biomarkers, versus patients managed with a clinical management algorithm. CALM was an open-label, randomised, controlled phase 3 study, done in 22 countries at 74 hospitals and outpatient centres, which evaluated adult patients (aged 18-75 years) with active endoscopic Crohn's disease (Crohn's Disease Endoscopic Index of Severity [CDEIS] >6; sum of CDEIS subscores of >6 in one or more segments with ulcers), a Crohn's Disease Activity Index (CDAI) of 150-450 depending on dose of prednisone at baseline, and no previous use of immunomodulators or biologics. Patients were randomly assigned at a 1:1 ratio to tight control or clinical management groups, stratified by smoking status (yes or no), weight (2 years) after 8 weeks of prednisone induction therapy, or earlier if they had active disease. In both groups, treatment was escalated in a stepwise manner, from no treatment, to adalimumab induction followed by adalimumab every other week, adalimumab every week, and lastly to both weekly adalimumab and daily azathioprine. This escalation was based on meeting treatment failure criteria, which differed between groups (tight control group before and after random assignment: faecal calprotectin ≥250 μg/g, C-reactive protein ≥5mg/L, CDAI ≥150, or prednisone use in the previous week; clinical management group before random assignment: CDAI decrease of 200; clinical management group after random assignment: CDAI decrease of management group, 0·9 years [SD 1·7]; tight control group, 1·0 year [2·3]) were randomly assigned to monitoring groups (n=122 per group

  4. Enhanced gas recovery program. Fourth annual report, October 1978-September 1979

    Energy Technology Data Exchange (ETDEWEB)

    Northrop, D A; Schuster, C L [eds.

    1979-11-01

    Massive hydraulic fracture diagnostic experiments continued in FY 79 with the major activity being focused on the development of wireline tool instrumentation. Nevada Test Site substantiate field data obtained in two experiments with Amoco in their Wattenberg field. A high-resolution, three-dimensional seismic survey program was initiated. The program will start with some experiments at shallow depths where the sand lenses outcrop and then move into greater depths to evaluate this technique. A logging program was also established to evaluate formation properties. Hydraulic and dynamic fracturing experiments were conducted adjacent to a tunnel complex at the Nevada Test Site and which are then directly observed by mining through the experiment area. Evaluation of fracturing tests at an interface between geologic formations with significantly different properties showed that the interface did not contain the fractures. A microcrack model has been formulated which downplays the importance of material properties and emphasizes the role of in-situ stresses for processes occurring at a crack tip. Multiple fracturing from a wellbore has been demonstrated for a High Energy Gas Frac concept. Finally, a Multi-Well Experiment has been defined whose objectives are to characterize in detail a lenticular gas reservoir of the Western United States and to evaluate state-of-the-art and developing technology for the recovery of gas from them.

  5. GAS BEARING

    Science.gov (United States)

    Skarstrom, C.W.

    1960-09-01

    A gas lubricated bearing for a rotating shaft is described. The assembly comprises a stationary collar having an annular member resiliently supported thereon. The collar and annular member are provided with cooperating gas passages arranged for admission of pressurized gas which supports and lubricates a bearing block fixed to the rotatable shaft. The resilient means for the annular member support the latter against movement away from the bearing block when the assembly is in operation.

  6. Asymptomatic hypospadias with tight meatal stricture in the father of twelve children

    OpenAIRE

    Katib, Atif A.

    2013-01-01

    Hypospadias is a highly prevalent congenital anomaly. English articles, indexed in PubMed, published the long-term sexual and reproductive outcome following hypospadias repair. Almost all repairable cases of hypospadias are operated in childhood. Although distal hypospadias does not interfere with fertility, it is worthy reporting a case of an elderly man, who fathers 12 children and has no urologic complaint, presented with unrepaired coronal hypospadias and severely tight external urethral ...

  7. Nanometric locking of the tight focus for optical microscopy and tip-enhanced microscopy

    International Nuclear Information System (INIS)

    Hayazawa, N; Furusawa, K; Kawata, S

    2012-01-01

    We have successfully stabilized the tight focus onto the sample surface of an optical microscope within ±1.0 nm for a virtually unlimited time duration. The time-dependent thermal drift of the tight focus and the mechanical tilt of the sample surface were simultaneously sensed by a non-optical means based on a capacitive sensor and were compensated for in real-time. This non-optical scheme is promising for the suppression of background light sources for optical microscopy. The focus stabilization is crucial for microscopic measurement at an interface, particularly when scanning a large surface area, because there is always a certain amount of mechanical tilt of the sample substrate, which degrades the contrast of the image. When imaging nanoscopic materials such as carbon nanotubes or silicon nanowires, more stringent nanometric stabilization of the focus position relative to such samples is required, otherwise it is often difficult to interpret the results from the observations. Moreover, the smaller the sample volume is, the smaller the signal becomes, resulting in a long exposure time at each position. In this sense, long-term stability of the tight focus is essential for both microscopic large area scanning and nanosized sample scanning (high-resolution/large-area imaging). In addition, the recently developed tip-enhanced microscopy requires long-term stability of the relative position of the tip, sample and focus position. We were able to successfully demonstrate a stability improvement for tip-enhanced microscopy in the same manner. The stabilization of the tight focus enables us to perform long-term and robust measurements without any degradation of optical signal, resulting in the capability of true nanometric optical imaging with good reproducibility and high precision. The technique presented is a simple add-on for any kind of optical microscope. (paper)

  8. Managing tight-binding receptors for new separations technologies. 1998 annual progress report

    International Nuclear Information System (INIS)

    Busch, D.H.; Givens, R.S.

    1998-01-01

    'Whereas such traditional separation methodologies as ion exchange and solvent extraction require rapid interaction between ligands and metal ions, the most strongly binding ligands invariably bind slowly; e.g., cryptates bind and dissociate more slowly than macrocycles, which are slower than open-chain chelating ligands. This project seeks to maximize the binding and dissociation rates for tight-binding receptors in order to make them more useful to separations science. An alternative slow-binding technology is also under exploration.'

  9. Secretion of Alpha-Hemolysin by Escherichia coli Disrupts Tight Junctions in Ulcerative Colitis Patients

    Science.gov (United States)

    Mirsepasi-Lauridsen, Hengameh Chloé; Du, Zhengyu; Struve, Carsten; Charbon, Godefroid; Karczewski, Jurgen; Krogfelt, Karen Angeliki; Petersen, Andreas Munk; Wells, Jerry M

    2016-01-01

    Objectives: The potential of Escherichia coli (E. coli) isolated from inflammatory bowel disease (IBD) patients to damage the integrity of the intestinal epithelium was investigated. Methods: E. coli strains isolated from patients with ulcerative colitis (UC) and healthy controls were tested for virulence capacity by molecular techniques and cytotoxic assays and transepithelial electric resistance (TER). E. coli isolate p19A was selected, and deletion mutants were created for alpha-hemolysin (α-hemolysin) (hly) clusters and cytotoxic necrotizing factor type 1 (cnf1). Probiotic E. coli Nissle and pathogenic E. coli LF82 were used as controls. Results: E. coli strains from patients with active UC completely disrupted epithelial cell tight junctions shortly after inoculation. These strains belong to phylogenetic group B2 and are all α-hemolysin positive. In contrast, probiotic E. coli Nissle, pathogenic E. coli LF82, four E. coli from patients with inactive UC and three E. coli strains from healthy controls did not disrupt tight junctions. E. coli p19A WT as well as cnf1, and single loci of hly mutants from cluster I and II were all able to damage Caco-2 (Heterogeneous human epithelial colorectal adenocarcinoma) cell tight junctions. However, this phenotype was lost in a mutant with knockout (Δ) of both hly loci (P<0.001). Conclusions: UC-associated E. coli producing α-hemolysin can cause rapid loss of tight junction integrity in differentiated Caco-2 cell monolayers. This effect was abolished in a mutant unable to express α-hemolysin. These results suggest that high Hly expression may be a mechanism by which specific strains of E. coli pathobionts can contribute to epithelial barrier dysfunction and pathophysiology of disease in IBD. PMID:26938480

  10. Oval-like hollow intensity distribution of tightly focused femtosecond laser pulses in air.

    Science.gov (United States)

    Li, Y T; Xi, T T; Hao, Z Q; Zhang, Z; Peng, X Y; Li, K; Jin, Z; Zheng, Z Y; Yu, Q Z; Lu, X; Zhang, J

    2007-12-24

    The propagation of a tightly focused femtosecond laser pulse in air has been investigated. Unlike long-distance self-guided propagation of short laser pulses, a novel oval-like hollow distribution of the laser intensity is observed in the experiments and reproduced by the numerical simulations. The formation of the hollow structures can be explained by the interplay between ionization-induced refraction and Kerr self-focusing.

  11. IMF - metallicity: a tight local relation revealed by the CALIFA survey

    OpenAIRE

    Martín-Navarro, Ignacio; Vazdekis, Alexandre; La Barbera, Francesco; Falcón-Barroso, Jesús; Lyubenova, Mariya; van de Ven, Glenn; Ferreras, Ignacio; Sánchez, S. F.; Trager, S. C.; García-Benito, R.; Mast, D.; Mendoza, M. A.; Sánchez-Blázquez, P.; Delgado, R. González; Walcher, C. J.

    2015-01-01

    Variations in the stellar initial mass function (IMF) have been invoked to explain the spectroscopic and dynamical properties of early-type galaxies. However, no observations have yet been able to disentangle the physical driver. We analyse here a sample of 24 early-type galaxies drawn from the CALIFA survey, deriving in a homogeneous way their stellar population and kinematic properties. We find that the local IMF is tightly related to the local metallicity, becoming more bottom-heavy toward...

  12. Evolution of permeability and microstructure of tight carbonates due to numerical simulation of calcite dissolution

    Science.gov (United States)

    Miller, Kevin; Vanorio, Tiziana; Keehm, Youngseuk

    2017-06-01

    The current study concerns fundamental controls on fluid flow in tight carbonate rocks undergoing CO2 injection. Tight carbonates exposed to weak carbonic acid exhibit order of magnitude changes in permeability while maintaining a nearly constant porosity with respect to the porosity of the unreacted sample. This study aims to determine—if not porosity—what are the microstructural changes that control permeability evolution in these rocks? Given the pore-scale nature of chemical reactions, we took a digital rock physics approach. Tight carbonate mudstone was imaged using X-ray microcomputed tomography. We simulated calcite dissolution using a phenomenological numerical model that stands from experimental and microstructural observations under transport-limited reaction conditions. Fluid flow was simulated using the lattice-Boltzmann method, and the pore wall was adaptively eroded at a rate determined by the local surface area and velocity magnitude, which we use in place of solvent flux. We identified preexisting, high-conductivity fluid pathways imprinted in the initial microstructure. Though these pathways comprise a subset of the total connected porosity, they accommodated 80 to 99% of the volumetric flux through the digital sample and localized dissolution. Porosity-permeability evolution exhibited two stages: selective widening of narrow pore throats that comprised preferential pathways and development and widening of channels. We quantitatively monitored attributes of the pore geometry, namely, porosity, specific surface area, tortuosity, and average hydraulic diameter, which we qualitatively linked to permeability. This study gives a pore-scale perspective on the microstructural origins of laboratory permeability-porosity trends of tight carbonates undergoing transport-limited reaction with CO2-rich fluid.

  13. Inertial Aided Kinematic GPS Cycle Slip Detection and Correction for GPS/INS Tightly Coupled System

    OpenAIRE

    HAN Houzeng; WANG Jian; LI Zengke

    2015-01-01

    In order to improve the navigation performance and robustness, a GPS/INS tightly coupled model has been developed, the INS related bias and ionospheric errors were compensated and corrected, the impact of combination observations on cycle slip detection was investigated, and four combinations with the characteristics of longer wavelength, smaller noise and lower ionosphere effect were determined, then an innovative inertial aided adaptive cycle slip detection and correction algorithm based on...

  14. Electromagnetic fields of an ultra-short tightly-focused radially-polarized laser pulse

    Science.gov (United States)

    Salamin, Yousef I.; Li, Jian-Xing

    2017-12-01

    Fully analytic expressions, for the electric and magnetic fields of an ultrashort and tightly focused laser pulse of the radially polarized category, are presented to lowest order of approximation. The fields are derived from scalar and vector potentials, along the lines of our earlier work for a similar pulse of the linearly polarized variety. A systematic program is also described from which the fields may be obtained to any desired accuracy, analytically or numerically.

  15. Requirements for gas quality and gas appliances

    NARCIS (Netherlands)

    Levinsky, Howard; Gersen, Sander; Kiewiet, Bert

    2015-01-01

    Introduction The gas transmission network in the Netherlands transports two different qualities of gas, low-calorific gas known as G-gas or L-gas and, high calorific gas (H-gas). These two gas qualities are transported in separate networks, and are connected by means of five blending and conversion

  16. Gas separating

    Science.gov (United States)

    Gollan, A.

    1988-03-29

    Feed gas is directed tangentially along the non-skin surface of gas separation membrane modules comprising a cylindrical bundle of parallel contiguous hollow fibers supported to allow feed gas to flow from an inlet at one end of a cylindrical housing through the bores of the bundled fibers to an outlet at the other end while a component of the feed gas permeates through the fibers, each having the skin side on the outside, through a permeate outlet in the cylindrical casing. 3 figs.

  17. Vascular expression of angiopoietin1, α5β1 integrin and tight junction proteins is tightly regulated during vascular remodeling in the post-ischemic brain.

    Science.gov (United States)

    Sun, Jialan; Yu, Liming; Huang, Shu; Lai, Xiaoyin; Milner, Richard; Li, Longxuan

    2017-10-24

    The post-stroke angiogenic response is accompanied by changes of tight junctions (TJs) of the blood-brain barrier (BBB). However, the precise dynamic change of TJ proteins (TJPs) in the different stages of stroke-induced vascular remodeling and the molecules mediating these processes have yet to be fully defined. To investigate the temporal relationship between changes in TJPs, the pro-angiogenic factor α5β1 integrin and the anti-permeability factor Ang1 in cerebral vessels following cerebral ischemic stroke, male C57Bl/6 mice were subject to 90min of ischemia by temporary occlusion of the middle cerebral artery followed by reperfusion and their brains analyzed 0, 1, 2, 4, 7 and 14days post-ischemia. Immunofluorescent studies demonstrated that in the ischemic penumbra, TJPs claudin-5 and ZO-1 levels decreased during the early stages of vascular remodeling, but then increased in the later stages. In contrast, within the ischemic core, TJPs levels decreased over the 14-day time-course, plateaued at day 4, and remained at low levels up to day 14. In the penumbra, Ang1 expression was induced, peaking at the same time point as α5β1 expression. Consistent with these findings, oxygen glucose deprivation/reperfusion induced expression of α5β1 and Ang1 on brain endothelial cell (BEC) in a similar manner in vitro, which correlated closely with BEC proliferation and increased expression of TJPs. Our results demonstrate that in the post-ischemic penumbra, a tight temporal correlation exists between the angiogenic markers α5β1 and Ang1 and the TJPs, suggesting a potential role for Ang1 and α5β1 in promoting BBB integrity following ischemic stroke. Copyright © 2017 IBRO. Published by Elsevier Ltd. All rights reserved.

  18. ACUTE EFFECTS OF DRY NEEDLING ON POSTERIOR SHOULDER TIGHTNESS. A CASE REPORT.

    Science.gov (United States)

    Passigli, Samuele; Plebani, Giuseppe; Poser, Antonio

    2016-04-01

    Posterior shoulder tightness has been associated with numerous shoulder disorders. Methods to increase posterior shoulder mobility may be beneficial. The purpose of this case report is to report the outcomes of a subject with posterior shoulder tightness treated with dry needling as a primary intervention strategy. The subject was a 46-year-old man who was referred to physical therapy with primary symptoms of shoulder pain and loss of motion consistent with subacromial impingement syndrome. Clinical findings upon examination revealed glenohumeral internal rotation and horizontal adduction losses of motion and reproduction of pain symptoms upon palpation of the infraspinatus, teres minor, and posterior deltoid. A single treatment of trigger point dry needling was used to decrease pain and improve range of motion. Following the intervention, clinically meaningful improvements were seen in pain and shoulder range of motion. This case report describes the use of trigger point dry needling in the treatment of a subject with posterior shoulder tightness. The immediate improvement seen in this subject following the dry needling to the infraspinatus, teres minor, and posterior deltoid muscles suggests that muscles may be a significant source of pain and range of motion limitation in this condition. Level 4.

  19. Tight coupling UFMArcGIS for simulating inundation depth in densely area

    Directory of Open Access Journals (Sweden)

    S. H. Kang

    2010-07-01

    Full Text Available The integration of hydrological models and Geographical Information Systems (GIS usually takes two approaches: loose coupling and tight coupling. This paper presents a tight coupling approach within a GIS environment that is achieved by integrating the urban flood model with the macro language of GIS. Such an approach affords an uncomplicated way to capitalize on the GIS visualization and spatial analysis functions, thereby significantly supporting the dynamic simulation process of hydrological modeling. The tight coupling approach is illustrated by UFMArcGIS (Urban Flood Model with ArcGIS, which is a realization of an urban flood model integrated with the VBA (visual basic of application language of ArcGIS. Within this model, major stages of model structures are created from the initial parameter input and transformation of datasets, intermediate maps are then visualized, and the results are finally presented in various graphical formats in their geographic context. This approach provides a convenient and single environment in which users can visually interact with the model, e.g. by adjusting parameters while simultaneously observing the corresponding results. This significantly facilitates users in the exploratory data analysis and decision-making stages in terms of the model applications.

  20. Does Iliopsoas Tightness Affects Synergistic Muscle Activity in Hip Extension During Stance Phase of Gait?

    Directory of Open Access Journals (Sweden)

    Shirin Aali

    2017-06-01

    Full Text Available Background and objective: Iliopsoas stiffness and restricted hip extension ROM affect muscle balance and lumbopelvic alignment. The purpose of this research is study of iliopsoas tightness’ effect on electromyographic activity of hip extensor synergists during gait. Methods: In this case-control study 15 adolescents with iliopsoas tightness as experimental group, and 15 healthy adolescents which matched based on age, height, weight, BMI, dominant leg, and sport experience participated voluntarily as control group. Surface electromyographic (sEMG activity of the gluteus maximus, adductor magnus, and biceps femoris, were measured between groups during stance phase of gait. Results: Individuals with restricted hip flexor muscle length demonstrated more gluteus maximus activation during terminal stance (p=0.001, more biceps femoris activation during mid stance (p=0.002 and late stance (p=0.001 and more adductor magnus activation during mid stance (p=0.04 and late stance (p=0.001. Discussion and conclusion: Adolescent soccer athletes with hip flexor muscle tightness exhibit more biceps femoris and adductor magnus and gluteus maximus activation during stance phase of gait. Thus, individuals with hip flexor muscle tightness appear to utilize different neuromuscular strategies to control lower extremity motion.

  1. Hybrid spherical cap plasmonic waveguide for tight mode confinement and long propagation length

    Science.gov (United States)

    Li, Kai; Yun, Maojin; Ge, Xiaohui; Kong, Weijin

    2015-08-01

    The special abilities of plasmonic waveguide including tight field confinement and beyond diffraction limit within nano-scale structure have been exploited in many different fields. In order to overcome the trade-off between tight mode confinement and long propagation length, many kinds of nano-scale structures have been proposed in recent years. In this paper, a novel hybrid plasmonic waveguide consisting of the layer of metal Ag, a spherical cap with low-index dielectric layer placed above the metal Ag and a high-index dielectric layer placed above the spherical cap is proposed and analyzed theoretically. The relations between the characteristics of the bound modes, such as mode confinement, propagation lengths, and parameters of the spherical cap, the curvature and width, are numerically investigated in detail. The simulation results show that the nano-scale confinement can be realized. The simulation result shows that the performance of the proposed spherical cap hybrid plasmonic waveguide is better than the rectangle or cylindrical hybrid plasmonic waveguide. Such hybrid plasmonic waveguide has a tight mode confinement and long propagation length. This novel structure provides a promising application for high-integration density photonic components.

  2. FY16/Q2 status report on initial dispersion calculations for tight crude oils project

    Energy Technology Data Exchange (ETDEWEB)

    Luketa, Anay [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Rudeen, David Keith [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-04-01

    The objective of this work is to assess dispersion distances of a vapor mixture of species released from a railcar containing a tight crude oil. Tight crude oils can have higher levels of light ends as compared to conventional crude oils [1], which if released and dispersed could pose a potential hazard with regards to a flash fire, explosion, and/or asphyxiation. A historical accident involving rail transport in Viareggio, Italy illustrates how the spillage of LPG can lead to severe damage as a result of a propagating vapor cloud [2]. One of 14 railcars was punctured after derailment, releasing about 110 m3 of LPG into a densely populated area (2000 persons/km2 ). The resulting vapor cloud propagated and infiltrated nearby buildings and houses which were an average of 10 m in height. Ignition of the cloud occurred approximately 100 to 300 seconds after the start of the spill. A flash fire and explosions resulted, killing 31 people. Evidence suggests that most deaths occurred due to the asphyxiation and thermal hazards from the flash fire. Thus, the motivation for this work is to assess if significant vapors can develop from a railcar carrying a tight crude oil and if this cloud could disperse potentially to nearby populations.

  3. Methods for estimating petrophysical parameters from well logs in tight oil reservoirs: a case study

    International Nuclear Information System (INIS)

    Zhao, Peiqiang; Zhuang, Wen; Mao, Zhiqiang; Tong, Zemin; Sun, Zhongchun; Wang, Zhenlin; Luo, Xingping

    2016-01-01

    Estimating petrophysical parameters from well logs plays a significant role in the exploration and development of tight oil resources, but faces challenges. What’s more, the methods for petrophysical parameters from well logs are paid little attention at present. In this paper, the typical tight oil reservoirs of Northwest China are used as an example. Based on the characteristics of mineralogy and fluids in the study field, the rock is assumed into five components which are clays, quartz and feldspar, carbonates, kerogen and pore fluids (porosity). The sum of kerogen content and porosity is defined as the apparent porosity. Then, two porosity log response equations are established. Once the clay content is determined by an individual method, the quartz and feldspar content, carbonate content and apparent porosity are calculated through the established equations. The kerogen content is the difference of the apparent porosity and porosity from nuclear magnetic resonance (NMR) logs. This paper also presents a new approach that combines the complex refractive index method (CRIM) and pseudo Archie method to compute saturation from dielectric logs, which avoids selection for the dielectric constants of each of the minerals. The effectiveness and reliability of these methods are verified by the successful application in the study of the target tight oil play in Northwest China. (paper)

  4. Two-Layer Tight Frame Sparsifying Model for Compressed Sensing Magnetic Resonance Imaging

    Directory of Open Access Journals (Sweden)

    Shanshan Wang

    2016-01-01

    Full Text Available Compressed sensing magnetic resonance imaging (CSMRI employs image sparsity to reconstruct MR images from incoherently undersampled K-space data. Existing CSMRI approaches have exploited analysis transform, synthesis dictionary, and their variants to trigger image sparsity. Nevertheless, the accuracy, efficiency, or acceleration rate of existing CSMRI methods can still be improved due to either lack of adaptability, high complexity of the training, or insufficient sparsity promotion. To properly balance the three factors, this paper proposes a two-layer tight frame sparsifying (TRIMS model for CSMRI by sparsifying the image with a product of a fixed tight frame and an adaptively learned tight frame. The two-layer sparsifying and adaptive learning nature of TRIMS has enabled accurate MR reconstruction from highly undersampled data with efficiency. To solve the reconstruction problem, a three-level Bregman numerical algorithm is developed. The proposed approach has been compared to three state-of-the-art methods over scanned physical phantom and in vivo MR datasets and encouraging performances have been achieved.

  5. The cultural dimension of tightness-looseness: An analysis of situational constraint in Estonia and Greece.

    Science.gov (United States)

    Realo, Anu; Linnamägi, Karmen; Gelfand, Michele J

    2015-06-01

    The importance of tightness-looseness as a dimension that explains a considerable amount of variance between cultures was demonstrated by Gelfand et al. (2011). Tight nations have many strong norms and a low tolerance of deviant behaviour, whereas loose nations have weak social norms and a high tolerance of deviant behaviour. The main aim of the current studies was to examine situational constraint in Estonia and Greece: that is, how the cultural dimension of tightness-looseness is manifested in everyday situations in those two countries. The findings of a questionnaire study (Study 1) suggested that, in general, there is higher constraint across everyday situations in Greece than in Estonia, but situational constraint in Greece is especially strong in school and organisational settings where people have hierarchically structured roles. The results of an observational study (Study 2) revealed a relatively high agreement between appropriateness of certain behaviours as judged by the respondents in Study 1 and the frequencies of observed behaviours in the two countries. Our findings suggest that the strength of situations may substantially vary both within and across cultures, and that the attitudes of the members about situational strength in their respective cultures are in concordance with observations of situations by neutral observers in how people in general behave in their culture. © 2014 International Union of Psychological Science.

  6. A modified Z-plasty technique for severe tightness of the gluteus maximus.

    Science.gov (United States)

    Nam, K W; Yoo, J J; Koo, K H; Yoon, K S; Kim, H J

    2011-02-01

    The majority of reports concern external snapping hips caused by the iliotibial band. Comparatively, little information is available regarding snapping hips caused by a gluteus maximus. Here we show that hip problems caused by a tight gluteus maximus can be treated using a modified Z-plasty technique. Fourteen hips in seven patients were diagnosed as snapping hips caused by a tight gluteus maximus. The main functional impairment is that when the hips were flexed, legs were abducted widely and could not be adducted. All had functional impairments irresponsive to conservative treatments besides snapping, whether painful or not, and all patients underwent surgery using a modified Z-plasty technique on the iliotibial band. All patients were followed up and the mean follow-up was 7 years. All patients had complete resolution of functional impairments, snapping, and pain after surgery. No patient needed revision surgery, and there were no complications, such as, abductor weakness, or irritation over the greater trochanter. We suggest that the intrinsic tendon contracture can cause serious functional impairment in patients with snapping due to a tight gluteus maximus. In this context, a modified Z-plasty technique offers a good surgical approach. © 2009 John Wiley & Sons A/S.

  7. GPS/UWB/MEMS-IMU tightly coupled navigation with improved robust Kalman filter

    Science.gov (United States)

    Li, Zengke; Chang, Guobin; Gao, Jingxiang; Wang, Jian; Hernandez, Alberto

    2016-12-01

    The integration of Global Positioning System (GPS) with Inertial Navigation System (INS) has been very intensively developed and widely applied in multiple areas. To further enhance the reliability and availability of GPS/INS integrated navigation in GPS challenging environment, range observation through ultra-wideband (UWB) is introduced in GPS/INS tightly coupled navigation. An improved robust Kalman filter is proposed and used to resist the influence of gross error from UWB observation in GPS/UWB/IMU tightly coupled navigation. The variance of the squared Mahalanobis distance in moving window is calculated, which brings as new judgement factor for gross errors in order to decrease the rate of false outlier identification. A simulation analysis shows that the improved robust Kalman filter is able to correctly identify gross errors and the rate of false judgment as zero. In order to validate the new robust filter, a real experiment is conducted. The results indicate that the improved robust Kalman filter used in GPS/UWB/INS tightly coupled navigation is able to remove the harmful effect of gross error in UWB observation. It clearly illustrates that the improved robust Kalman filter is very effective, and all the simulated small and large gross errors added to UWB distance observation are successfully identified.

  8. Resource-assessment perspectives for unconventional gas systems

    Science.gov (United States)

    Schmoker, J.W.

    2002-01-01

    Concepts are described for assessing those unconventional gas systems that can also be defined as continous accumulations. Continuous gas accumulations exist more or less independently of the water column and do not owe their existence directly to the bouyancy of gas in water. They cannot be represented in terms of individual, countable fields or pools delineated by downdip water contacts. For these reasons, traditional resource-assessment methods based on estimating the sizes and numbers of undiscovered discrete fields cannot not be applied to continuous accumulations. Specialized assessment methods are required. Unconventional gas systems that are also continous accumulations include coalbed methane, basin-centered gas, so-called tight gas, fractured shale (and chalk) gas, and gas hydrates. Deep-basin and bacterial gas systems may or may not be continuous accumulations, depending on their geologic setting. Two basic resource-assessment approaches have been employed for continous accumulations. The first approach is based on estimates of gas in place. A volumetric estimate of total gas in place is commonly coupled with an overall recovery factor to narrow the assessment scope from a treatment of gas volumes residing in sedimentary strata to a prediction of potential additions to reserves. The second approach is based on the production performance of continous gas reservoirs, as shown empirically by wells and reservoir-simulation models. In these methods, production characteristics (as opposed to gas in place) are the foundation for forecasts of potential additions to reserves.

  9. Natural gas production verification tests

    International Nuclear Information System (INIS)

    1992-02-01

    This Environmental Assessment (EA) has been prepared by the Department of Energy (DOE) in compliance with the requirements of the National Environmental Policy Act of 1969. The Department of Energy (DOE) proposes to fund, through a contract with Petroleum Consulting Services, Inc. of Canton, Ohio, the testing of the effectiveness of a non-water based hydraulic fracturing treatment to increase gas recovery from low-pressure, tight, fractured Devonian Shale formations. Although Devonian Shales are found in the Appalachian, Michigan, and Illinois Basins, testing will be done only in the dominant, historical five state area of established production. The objective of this proposed project is to assess the benefits of liquid carbon dioxide (CO 2 )/sand stimulations in the Devonian Shale. In addition, this project would evaluate the potential nondamaging (to the formation) properties of this unique fracturing treatment relative to the clogging or chocking of pores and fractures that act as gas flow paths to the wellbore in the target gas-producing zones of the formation. This liquid CO 2 /sand fracturing process is water-free and is expected to facilitate gas well cleanup, reduce the time required for post-stimulation cleanup, and result in improved production levels in a much shorter time than is currently experienced

  10. An Integrated Rock Typing Approach for Unraveling the Reservoir Heterogeneity of Tight Sands in the Whicher Range Field of Perth Basin, Western Australia

    DEFF Research Database (Denmark)

    Ilkhchi, Rahim Kadkhodaie; Rezaee, Reza; Harami, Reza Moussavi

    2014-01-01

    between pore system properties and depositional and diagenetic characteristics in each sand type, reservoir rock types were extracted. The identified reservoir rock types are in fact a reflection of internal reservoir heterogeneity related to pore system properties. All reservoir rock types...... are characterized by a compacted fabric and cemented framework. But distribution and dominance of diagenetic products in each of them depend on primary depositional composition and texture. The results show that reservoir rock typing based on three aspects of reservoir sandstones (depositional properties......Tight gas sands in Whicher Range Field of Perth Basin show large heterogeneity in reservoir characteristics and production behavior related to depositional and diagenetic features. Diagenetic events (compaction and cementation) have severely affected the pore system. In order to investigate...

  11. Landfill gas

    International Nuclear Information System (INIS)

    Hartnell, Gaynor

    2000-01-01

    Following the UK Government's initiative for stimulating renewable energy through the Non-Fossil Fuel Obligation (NFFO), the UK landfill gas industry has more than trebled in size in just 4 years. As a result, UK companies are now in a strong position to offer their skills and services overseas. Ireland, Greece and Spain also resort heavily to disposal to landfill. Particularly rapid growth of the landfill gas market is expected in the OECD-Pacific and NAFTA areas. The article explains that landfill gas is a methane-rich mixture produced by anaerobic decomposition of organic wastes in landfills: under optimum conditions, up to 500 cubic meters of gas can be obtained from 1 tonne of biodegradable waste. Data on the number and capacity of sites in the UK are given. The Landfill Gas Association runs courses to counteract the skills shortage in the UK, and tailored courses for overseas visitors are planned

  12. Changes in intestinal tight junction permeability associated with industrial food additives explain the rising incidence of autoimmune disease.

    Science.gov (United States)

    Lerner, Aaron; Matthias, Torsten

    2015-06-01

    The incidence of autoimmune diseases is increasing along with the expansion of industrial food processing and food additive consumption. The intestinal epithelial barrier, with its intercellular tight junction, controls the equilibrium between tolerance and immunity to non-self-antigens. As a result, particular attention is being placed on the role of tight junction dysfunction in the pathogenesis of AD. Tight junction leakage is enhanced by many luminal components, commonly used industrial food additives being some of them. Glucose, salt, emulsifiers, organic solvents, gluten, microbial transglutaminase, and nanoparticles are extensively and increasingly used by the food industry, claim the manufacturers, to improve the qualities of food. However, all of the aforementioned additives increase intestinal permeability by breaching the integrity of tight junction paracellular transfer. In fact, tight junction dysfunction is common in multiple autoimmune diseases and the central part played by the tight junction in autoimmune diseases pathogenesis is extensively described. It is hypothesized that commonly used industrial food additives abrogate human epithelial barrier function, thus, increasing intestinal permeability through the opened tight junction, resulting in entry of foreign immunogenic antigens and activation of the autoimmune cascade. Future research on food additives exposure-intestinal permeability-autoimmunity interplay will enhance our knowledge of the common mechanisms associated with autoimmune progression. Copyright © 2015. Published by Elsevier B.V.

  13. Non-proximate mass spectrometry using a heated 1-m long PTFE tube and an air-tight APCI ion source

    Energy Technology Data Exchange (ETDEWEB)

    Usmanov, Dilshadbek T. [Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511 (Japan); Institute of Ion-Plasma and Laser Technologies, Durmon Yoli Street 33, 100125, Tashkent (Uzbekistan); Hiraoka, Kenzo, E-mail: hiraoka@yamanashi.ac.jp [Clean Energy Research Center, University of Yamanashi, Takeda-4, Kofu, Yamanashi, 400-8511 (Japan); Wada, Hiroshi [Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, 496 Izumi, Chikugo, Fukuoka 833-0041 (Japan); Matsumura, Masaya; Sanada-Morimura, Sachiyo [Kyushu Okinawa Agricultural Research Center, National Agriculture and Food Research Organization, Suya 2421, shiKo, Kumamoto 861-1192 (Japan); Nonami, Hiroshi [Plant Biophysics/Biochemistry Research Laboratory, Faculty of Agriculture, Ehime University, 3-5-7 T Tarumi, 790-0905, Matsuyama (Japan); Yamabe, Shinichi, E-mail: yamabesh@gmail.com [Department of Material Science, Nara Institute of Science and Technology, Takayama-cho, 8916-5, Ikoma, Nara, 630−0101 (Japan)

    2017-06-22

    Direct and rapid trace-level gas analysis is highly needed in various fields such as safety and security, quality control, food analysis, and forensic medicine. In many cases, the real samples are bulky and are not accessible to the space-limited ion source of the mass spectrometer. In order to circumvent this problem, we developed an airtight atmospheric-pressure chemical ionization (APCI) ion source equipped with a flexible 1-m-long, 2-mm-i.d. PTFE sniffing tube. The ambient air bearing sample gas was sucked into the heated PTFE tube (130 °C) and was transported to the air-tight ion source without using any extra pumping system or a Venturi device. Analytes were ionized by an ac corona discharge located at 1.5 mm from the inlet of the mass spectrometer. By using the airtight ion source, all the ionized gas in the ion source was introduced into the vacuum of the mass spectrometer via only the evacuation of the mass spectrometer (1.6 l min{sup −1}). Sub-pg limits of detection were obtained for carbaryl and trinitrotoluene. Owing to its flexibility and high sensitivity, the sniffing tube coupled with a mass spectrometer can be used as the stethoscope for the high-sensitive gas analysis. The experimental results obtained for drugs, hydrogen peroxide and small alkanes were discussed by DFT calculations. - Highlights: • Non-proximate mass spectrometry for the trace-level gas analysis was developed. • Using a 1-m long flexible PTFE tube, it can be applicable to complicated-shape real-world samples. • By atmospheric pressure chemical ionization in the airtight ion source, sub-pg limits of detection were attained. • Adsorption of less-volatility compounds was negligible with the tube temperature at 130° C. • Novel experimental results obtained were fully examined by density functional theory calculations.

  14. Natural gas supply-demand situation and prospect in China

    Directory of Open Access Journals (Sweden)

    Zhang Kang

    2014-10-01

    Full Text Available Since the 21st century, the reserves of conventional natural gas as well as tight gas in China have been decreasing and their annual production growth rates have been generally reduced from double-digit to one-digit number of percentage. It is predicted that natural gas production will possibly reach up to 134 billion m3 in 2015; and if the marketable rate is 90%, the gas supply volume will probably be 120.6 billion m3 in 2015. Since shale gas development just has started currently, about 0.6 billion m3 of the marketable shale gas will be added to gas supply in 2015. The CBM gas production especially such gas consumption has long been lagged behind the expected targets, and what's more, flaws exist in their statistics; on this basis, it is assumed that the marketable CBM gas will be 4 billion Nm 3 in 2015. With so many achievements made in the coal gas exploitation, it is forecasted that about 5.5 billion m3 coal gas will be added to gas supply in 2015. In total, the domestic fuel gas supply is roughly estimated to be 131 billion m3 in 2015; if the gas consumption in the year is presumably 231 billion m3, about 100 billion m3 gas will then be imported in 2015. From the presumable actual imports of piped gas and LNG terminals, there is still a gap of 27–30 billion m3 in 2015. Therefore, it is suggested that more LNG receiving terminals be put into production in advance and the increment of import gas be needed from Middle Asia. Also, it is proposed that the statistics be completed on the practical marketable fuel gas quantity in the fundamental study of energy planning in the National 13th Five-Year Plan. In conclusion, the economic system reform process is the key to the further development of oil and gas industry in China.

  15. Identification of MarvelD3 as a tight junction-associated transmembrane protein of the occludin family

    Directory of Open Access Journals (Sweden)

    Balda Maria S

    2009-12-01

    Full Text Available Abstract Background Tight junctions are an intercellular adhesion complex of epithelial and endothelial cells, and form a paracellular barrier that restricts the diffusion of solutes on the basis of size and charge. Tight junctions are formed by multiprotein complexes containing cytosolic and transmembrane proteins. How these components work together to form functional tight junctions is still not well understood and will require a complete understanding of the molecular composition of the junction. Results Here we identify a new transmembrane component of tight junctions: MarvelD3, a four-span transmembrane protein. Its predicted transmembrane helices form a Marvel (MAL and related proteins for vesicle traffic and membrane link domain, a structural motif originally discovered in proteins involved in membrane apposition and fusion events, such as the tight junction proteins occludin and tricellulin. In mammals, MarvelD3 is expressed as two alternatively spliced isoforms. Both isoforms exhibit a broad tissue distribution and are expressed by different types of epithelial as well as endothelial cells. MarvelD3 co-localises with occludin at tight junctions in intestinal and corneal epithelial cells. RNA interference experiments in Caco-2 cells indicate that normal MarvelD3 expression is not required for the formation of functional tight junctions but depletion results in monolayers with increased transepithelial electrical resistance. Conclusions Our data indicate that MarvelD3 is a third member of the tight junction-associated occludin family of transmembrane proteins. Similar to occludin, normal expression of MarvelD3 is not essential for the formation of functional tight junctions. However, MarvelD3 functions as a determinant of epithelial paracellular permeability properties.

  16. Western Gas Sands Project: stratigrapy of the Piceance Basin

    Energy Technology Data Exchange (ETDEWEB)

    Anderson, S. (comp.)

    1980-08-01

    The Western Gas Sands Project Core Program was initiated by US DOE to investigate various low permeability, gas bearing sandstones. Research to gain a better geological understanding of these sandstones and improve evaluation and stimulation techniques is being conducted. Tight gas sands are located in several mid-continent and western basins. This report deals with the Piceance Basin in northwestern Colorado. This discussion is an attempt to provide a general overview of the Piceance Basin stratigraphy and to be a useful reference of stratigraphic units and accompanying descriptions.

  17. Asian gas

    International Nuclear Information System (INIS)

    Masuda, T.

    1990-01-01

    This paper reports on natural gas which now appears ready to take a leading role on the world energy stage. Demand for natural gas, and specifically LNG, will be strong throughout the world, particularly in Asia. Indonesia and Malaysia will become much more dependent on natural gas in the Asian market. In Thailand, where remarkable economic growth has been fueled by imported oil and domestically produced natural gas, LNG may soon have to be imported from neighboring countries. The author sees Thailand's imports of natural gas increasing from 1.5 to 4.5 million tons annually. Similarly, Korea's imports of LNG will rise from 2 to 8 million tons between 1987 and 2000. In Japan, energy demand is expected to increase at an even faster rate in the 1990s. Given the opposition to nuclear power generation and growing concern about the greenhouse effect, it is likely that LNG will satisfy a major portion of Japan's increasing demand for energy. Japanese gas companies are studying the possibility of establishing a national pipeline network to move gas beyond metropolitan areas

  18. Gas turbines

    Energy Technology Data Exchange (ETDEWEB)

    Farahan, E.; Eudaly, J.P.

    1978-10-01

    This evaluation provides performance and cost data for commercially available simple- and regenerative-cycle gas turbines. Intercooled, reheat, and compound cycles are discussed from theoretical basis only, because actual units are not currently available, except on a special-order basis. Performance characteristics investigated include unit efficiency at full-load and off-design conditions, and at rated capacity. Costs are tabulated for both simple- and regenerative-cycle gas turbines. The output capacity of the gas turbines investigated ranges from 80 to 134,000 hp for simple units and from 12,000 to 50,000 hp for regenerative units.

  19. Maximize Liquid Oil Production from Shale Oil and Gas Condensate Reservoirs by Cyclic Gas Injection

    Energy Technology Data Exchange (ETDEWEB)

    Sheng, James

    2017-11-17

    The current technology to produce shale oil reservoirs is the primary depletion using fractured wells (generally horizontal wells). The oil recovery is less than 10%. The prize to enhance oil recovery (EOR) is big. Based on our earlier simulation study, huff-n-puff gas injection has the highest EOR potential. This project was to explore the potential extensively and from broader aspects. The huff-n-puff gas injection was compared with gas flooding, water huff-n-puff and waterflooding. The potential to mitigate liquid blockage was also studied and the gas huff-n-puff method was compared with other solvent methods. Field pilot tests were initiated but terminated owing to the low oil price and the operator’s budget cut. To meet the original project objectives, efforts were made to review existing and relevant field projects in shale and tight reservoirs. The fundamental flow in nanopores was also studied.

  20. Development of a Simulation Framework for Analyzing Security of Supply in Integrated Gas and Electric Power Systems

    NARCIS (Netherlands)

    Pambour, Kwabena Addo; Erdener, Burcin Cakir; Bolado-Lavin, Ricardo; Dijkema, Gerhard

    2017-01-01

    Gas and power networks are tightly coupled and interact with each other due to physically interconnected facilities. In an integrated gas and power network, a contingency observed in one system may cause iterative cascading failures, resulting in network wide disruptions. Therefore, understanding

  1. Development of a Gas Systems Analysis Model (GSAM)

    International Nuclear Information System (INIS)

    Becker, A.B.; Pepper, W.J.

    1995-01-01

    Objective of developing this model (GSAM) is to create a comprehensive, nonproprietary, PC-based model of domestic gas industry activity. The system can assess impacts of various changes in the natural gas system in North America; individual and collective impacts due to changes in technology and economic conditions are explicitly modeled in GSAM. Major gas resources are all modeled, including conventional, tight, Devonian Shale, coalbed methane, and low-quality gas sources. The modeling system assesses all key components of the gas industry, including available resources, exploration, drilling, completion, production, and processing practices. Distribution, storage, and utilization of natural gas in a dynamic market-gased analytical structure is assessed. GSAM is designed to provide METC managers with a tool to project impacts of future research, development, and demonstration benefits

  2. Tight Skin 2 Mice Exhibit Delayed Wound Healing Caused by Increased Elastic Fibers in Fibrotic Skin.

    Science.gov (United States)

    Long, Kristen B; Burgwin, Chelsea M; Huneke, Richard; Artlett, Carol M; Blankenhorn, Elizabeth P

    2014-09-01

    Rationale: The Tight Skin 2 (Tsk2) mouse model of systemic sclerosis (SSc) has many features of human disease, including tight skin, excessive collagen deposition, alterations in the extracellular matrix (ECM), increased elastic fibers, and occurrence of antinuclear antibodies with age. A tight skin phenotype is observed by 2 weeks of age, but measurable skin fibrosis is only apparent at 10 weeks. We completed a series of wound healing experiments to determine how fibrosis affects wound healing in Tsk2/+ mice compared with their wild-type (WT) littermates. Method: We performed these experiments by introducing four 4 mm biopsy punched wounds on the back of each mouse, ventral of the midline, and observed wound healing over 10 days. Tsk2/+ mice showed significantly delayed wound healing and increased wound size compared with the WT littermates at both 5 and 10 weeks of age. We explored the potential sources of this response by wounding Tsk2/+ mice that were genetically deficient either for the NLRP3 inflammasome (a known fibrosis mediator), or for elastic fibers in the skin, using a fibulin-5 knockout. Conclusion: We found that the loss of elastic fibers restores normal wound healing in the Tsk2/+ mouse and that the loss of the NLRP3 inflammasome had no effect. We conclude that elastic fiber dysregulation is the primary cause of delayed wound healing in the Tsk2/+ mouse and therapies that promote collagen deposition in the tissue matrix in the absence of elastin deposition might be beneficial in promoting wound healing in SSc and other diseases.

  3. Percutaneous medial collateral ligament release in arthroscopic medial meniscectomy in tight knees.

    Science.gov (United States)

    Fakioglu, Onur; Ozsoy, Mehmet Hakan; Ozdemir, Haci Mustafa; Yigit, Hasan; Cavusoglu, Ali Turgay; Lobenhoffer, Philipp

    2013-07-01

    Visualization and surgery of tears in the posterior medial meniscus are difficult in tight knees. Iatrogenic chondral lesions might cause serious morbidity, and residual tears may result in inadequate symptom relief. We evaluated the clinical and radiological results of superficial medial collateral ligament (MCL) release during arthroscopic medial meniscectomy in tight knees. Eighteen patients [median age: 43 years (22-59); median follow-up: 8.3 months (6-12)] who underwent arthroscopic meniscectomy were included in the study. Patients with ligamentous injuries, severe chondral damage or meniscal repairs were excluded. Preoperatively, anteroposterior knee radiographs were obtained with 11-kg valgus stress using a specialized instrument. During the operation, if opening of the medial knee in 30° flexion under 11-kg valgus stress was inadequate, controlled release of the posterior portion of the MCL was performed using a 16-gauge needle. Intraoperative valgus stress was monitored using a specially designed lateral support with mounted load cell. MCL injury was evaluated both with magnetic resonance imaging (MRI) and valgus stress radiographs, which were obtained in the 1st week and 3rd and 6th months postoperatively to monitor healing of the elongated MCL. In all patients, meniscectomy could be performed with adequate visualization of the posterior medial meniscus and without iatrogenic chondral injury. The median medial joint space width on valgus stress radiographs was 7.1 mm preoperatively and 9.1, 8.0 and 7.2 mm in the 1st week, and 3rd and 6th months, respectively (p < 0.0001). On MRI, the injured structure was the posterior two-thirds of the MCL. Median Lysholm score, which was 42 points before the operation, had increased to 94 points at the final follow-up (p = 0.0002). Controlled release of the MCL in tight knees allowed easier handling in posterior medial meniscus tears and a better understanding of tear configurations, avoiding iatrogenic chondral

  4. Effect of frequency of static stretching on flexibility, hamstring tightness and electromyographic activity.

    Science.gov (United States)

    Marques, A P; Vasconcelos, A A P; Cabral, C M N; Sacco, I C N

    2009-10-01

    We compared the effect of the number of weekly repetitions of a static stretching program on the flexibility, hamstring tightness and electromyographic activity of the hamstring and of the triceps surae muscles. Thirty-one healthy subjects with hamstring tightness, defined as the inability to perform total knee extension, and shortened triceps surae, defined by a tibiotarsal angle wider than 90 degrees during trunk flexion, were divided into three groups: G1 performed the stretching exercises once a week; G2, three times a week, and G3, five times a week. The parameters were determined before and after the stretching program. Flexibility improved in all groups after intervention, from 7.65 +/- 10.38 to 3.67 +/- 12.08 in G1, from 10.73 +/- 12.07 to 0.77 +/- 10.45 in G2, and from 14.20 +/- 10.75 to 6.85 +/- 12.19 cm in G3 (P flexibility was higher in G2 than in G1 (P = 0.018), while G2 and G3 showed no significant difference (G1: 4 +/- 2.17, G2: 10 +/- 5.27; G3: 7.5 +/- 4.77 cm). Hamstring tightness improved in all groups, from 37.90 +/- 6.44 to 29 +/- 11.65 in G1, from 39.82 +/- 9.63 to 21.91 +/- 8.40 in G2, and from 37.20 +/- 6.63 to 26.10 +/- 5.72 degrees in G3 (P flexibility and range of motion compared to subjects exercising once a week, with results similar to those of subjects who exercised five times a week.

  5. Differences in regulation of tight junctions and cell morphology between VHL mutations from disease subtypes

    Directory of Open Access Journals (Sweden)

    Isanova Bella

    2009-07-01

    Full Text Available Abstract Background In von Hippel-Lindau (VHL disease, germline mutations in the VHL tumor suppressor gene cause clear cell renal carcinomas, hemangioblastomas, and pheochromocytomas. The VHL gene product is part of an ubiquitin E3 ligase complex and hypoxia-inducible factor alpha (HIF-α is a key substrate, although additional VHL functions have been described. A genotype-phenotype relationship exists in VHL disease such that specific VHL mutations elicit certain subsets of these tumors. Here, we examine VHL genotype-phenotype correlations at the cellular level, focusing on the regulation of tight junctions and cell morphology. Methods Wild-type and various mutant VHL proteins representing VHL disease subtypes were stably expressed in 3 VHL-negative renal carcinoma cell lines. Using these cell lines, the roles of various VHL-associated cellular functions in regulation of cell morphology were investigated. Results As a whole, type 1 mutants varied greatly from type 2 mutants, demonstrating high levels of HIF-2α, cyclin D1 and α5 integrin, lower p27 levels, and a spindly, fibroblastic cellular appearance. Type 2 mutations demonstrated an epithelial morphology similar to wild-type VHL in the majority of the renal cell lines used. Knockdown of p27 in cells with wild-type VHL led to perturbations of both epithelial morphology and ZO-1 localization to tight junctions. ZO-1 localization correlated well with VHL disease subtypes, with greater mislocalization observed for genotypes associated with a higher risk of renal carcinoma. HIF-2α knockdown in 786-O partially restored ZO-1 localization, but did not restore an epithelial morphology. Conclusion VHL has both HIF-α dependent and HIF-α independent functions in regulating tight junctions and cell morphology that likely impact the clinical phenotypes seen in VHL disease.

  6. Application of Reservoir Flow Simulation Integrated with Geomechanics in Unconventional Tight Play

    Science.gov (United States)

    Lin, Menglu; Chen, Shengnan; Mbia, Ernest; Chen, Zhangxing

    2018-01-01

    Multistage hydraulic fracturing techniques, combined with horizontal drilling, have enabled commercial production from the vast reserves of unconventional tight formations. During hydraulic fracturing, fracturing fluid and proppants are pumped into the reservoir matrix to create the hydraulic fractures. Understanding the propagation mechanism of hydraulic fractures is essential to estimate their properties, such as half-length. In addition, natural fractures are often present in tight formations, which might be activated during the fracturing process and contribute to the post-stimulation well production rates. In this study, reservoir simulation is integrated with rock geomechanics to predict the well post-stimulation productivities. Firstly, a reservoir geological model is built based on the field data collected from the Montney formation in the Western Canadian Sedimentary Basin. The hydraulic fracturing process is then simulated through an integrated approach of fracturing fluid injection, rock geomechanics, and tensile failure criteria. In such a process, the reservoir pore pressure increases with a continuous injection of the fracturing fluid and proppants, decreasing the effective stress exerted on the rock matrix accordingly as the overburden pressure remains constant. Once the effective stress drops to a threshold value, tensile failure of the reservoir rock occurs, creating hydraulic fractures in the formation. The early production history of the stimulated well is history-matched to validate the predicted fracture geometries (e.g., half-length) generated from the fracturing simulation process. The effects of the natural fracture properties and well bottom-hole pressures on well productivity are also studied. It has been found that nearly 40% of hydraulic fractures propagate in the beginning stage (the pad step) of the fracturing schedule. In addition, well post-stimulation productivity will increase significantly if the natural fractures are propped or

  7. Tight binding simulation study on zigzag single-walled carbon nanotubes

    Science.gov (United States)

    Sharma, Deepa; Jaggi, Neena; Gupta, Vishu

    2018-01-01

    Tight binding simulation studies using the density functional tight binding (DFTB) model have been performed on various zigzag single-walled carbon-nanotubes (SWCNTs) to investigate their electronic properties using DFTB module of the Material Studio Software version 7.0. Various combinations of different eigen-solvers and charge mixing schemes available in the DFTB Module have been tried to chalk out the electronic structure. The analytically deduced values of the bandgap of (9, 0) SWCNT were compared with the experimentally determined value reported in the literature. On comparison, it was found that the tight binding approximations tend to drastically underestimate the bandgap values. However, the combination of Anderson charge mixing method with standard eigensolver when implemented using the smart algorithm was found to produce fairly close results. These optimized model parameters were then used to determine the band structures of various zigzag SWCNTs. (9, 0) Single-walled Nanotube which is extensively being used for sensing NH3, CH4 and NO2 has been picked up as a reference material since its experimental bandgap value has been reported in the literature. It has been found to exhibit a finite energy bandgap in contrast to its expected metallic nature. The study is of utmost significance as it not only probes and validates the simulation route for predicting suitable properties of nanomaterials but also throws light on the comparative efficacy of the different approximation and rationalization quantum mechanical techniques used in simulation studies. Such simulation studies if used intelligently prove to be immensely useful to the material scientists as they not only save time and effort but also pave the way to new experiments by making valuable predictions.

  8. Hydraulic fracturing to enhance geothermal energy recovery in deep and tight formations. Modell approach in petrothermy research project OPTIRISS

    Energy Technology Data Exchange (ETDEWEB)

    Rafiee, M.M.; Schmitz, S.; Barsch, M. [DBI - Gastechnologisches Institut gGmbH, Freiberg (Germany)

    2013-08-01

    In Germany numerous projects were successfully conducted in developments of geothermal energy which applied so far mostly for the hydrothermal deposit type. In Thuringia and Saxony there are currently project developments of geothermal resource taking into account for deep, tight formations in petrothermy and Enhanced geothermal system, (EGS). One of the potential tasks in generating these petrothermal producers and in the design of the underground power plant appears to be hydraulic fracturing with multi frac method. This is to create the heat exchanger surfaces in the rock and ensure maximum volumetric flow through it. Therefore it is very important for a sustainable heat production. However the promise of its adequate conductivity in the deep formation is one of the dominant contests in geothermal energy industry. In a multi frac method, two wells (normally horizontal wellbores at different depths) are drilled in direction of minimum horizontal stress of the formation rock. By multiple frac operation in separate sections, flow paths are generated between the wells through which it is possible to extract the heat from the rock. The numerical simulation of hydraulic fracture propagation processes in the rock is mainly from the research in the area of oil and gas industry. These techniques are mainly used for very low permeable formations in petroleum engineering (e.g. Shale gas). The development is at the beginning for EGS (e.g. granites). In this work single and multi fracking propagation processes in a synthetic example of deep hard formation are investigated. The numerical simulation is carried out to design and characterize frac processes and frac dimensions. Sensitivities to various rock parameters and different process designs are examined and optimum criteria are concluded. This shows that the minimum stress profile has the most effective role and should be modelled properly. The analysis indicates the optimum fracture length and height for adequate thermal

  9. Electronic transport properties of fullerene functionalized carbon nanotubes: Ab initio and tight-binding calculations

    DEFF Research Database (Denmark)

    Fürst, Joachim Alexander; Hashemi, J.; Markussen, Troels

    2009-01-01

    techniques and tight-binding calculations to illustrate these materials' transmission properties and give physical arguments to interpret the numerical results. Specifically, above the Fermi energy we find a strong reduction in electron transmission due to localized states in certain regions of the structure......Fullerene functionalized carbon nanotubes-NanoBuds-form a novel class of hybrid carbon materials, which possesses many advantageous properties as compared to the pristine components. Here, we report a theoretical study of the electronic transport properties of these compounds. We use both ab initio...

  10. Self-consistent tight-binding model of B and N doping in graphene

    DEFF Research Database (Denmark)

    Pedersen, Thomas Garm; Pedersen, Jesper Goor

    2013-01-01

    . The impurity potential depends sensitively on the impurity occupancy, leading to a self-consistency requirement. We solve this problem using the impurity Green's function and determine the self-consistent local density of states at the impurity site and, thereby, identify acceptor and donor energy resonances.......Boron and nitrogen substitutional impurities in graphene are analyzed using a self-consistent tight-binding approach. An analytical result for the impurity Green's function is derived taking broken electron-hole symmetry into account and validated by comparison to numerical diagonalization...

  11. Tight Bounds for Beacon-Based Coverage in Simple Rectilinear Polygons

    KAUST Repository

    Bae, Sang Won

    2016-03-21

    We establish tight bounds for beacon-based coverage problems. In particular, we show that $$\\\\lfloor \\\\frac{n}{6} \\ floor $$⌊n6⌋ beacons are always sufficient and sometimes necessary to cover a simple rectilinear polygon P with n vertices. When P is monotone and rectilinear, we prove that this bound becomes $$\\\\lfloor \\\\frac{n+4}{8} \\ floor $$⌊n+48⌋. We also present an optimal linear-time algorithm for computing the beacon kernel of P.

  12. Critical experiments supporting underwater storage of tightly packed configurations of spent fuel rods

    International Nuclear Information System (INIS)

    Hoovler, G.S.; Baldwin, M.N.

    1981-04-01

    Criticla arrays of 2.5%-enriched UO 2 fuel rods that simulate underwater rod storage of spent power reactor fuel are being constructed. Rod storage is a term used to describe a spent fuel storage concept in which the fuel bundles are disassembled and the rods are packed into specially designed cannisters. Rod storage would substantially increase the amount of fuel that could be stored in available space. These experiments are providing criticality data against which to benchmark nuclear codes used to design tightly packed rod storage racks

  13. Safe disposal of cytotoxic waste: an evaluation of an air-tight system.

    Science.gov (United States)

    Craig, Gemma; Wadey, Charlotte

    2017-09-07

    A 3-month evaluation was undertaken at the Kent Oncology Centre's chemotherapy day unit (CDU) to trial an air-tight sealing disposal system for cytotoxic waste management. Research has identified the potential risk to staff who handle waste products that are hazardous to health. Staff safety was a driving force behind a trial of a new way of working. This article provides an overview of the evaluation of the Pactosafe system in one clinical area, examining reviews by oncology healthcare workers, the practicalities in the clinical setting, training, cost effectiveness and the environmental benefits.

  14. Post irradiation examination of tight fit garter springs from PHWR after 15 HOY of operation

    International Nuclear Information System (INIS)

    Dubey, J.S.; Shriwastaw, R.S.; Kumar, Ashwini; Shah, Priti Kotak; Rath, B.N.; Kumar, Sunil; Mishra, Prerna; Alur, V.D.; Mallik, G.K.; Anantharaman, S.

    2015-01-01

    Tight fit irradiated garter springs made of Zr-2.5Nb-0.5Cu, belonging to Pressurized Heavy Water Reactors (PHWRs), which had experienced 15 Hot Operation Years (HOY) of operation were subjected to visual, dimensional, metallographic examination and relevant mechanical tests such as stretch, crush and rolling-fatigue tests. The girdle wires, of these garter springs, made of Zr-2 were subjected to tension and bend tests. Methodology of the tests conducted and results of PIE are presented. Significance of the test results are discussed in view of its continued operation in reactor. (author)

  15. The Tightness of the Kesten-Stigum Reconstruction Bound of Symmetric Model with Multiple Mutations

    Science.gov (United States)

    Liu, Wenjian; Jammalamadaka, Sreenivasa Rao; Ning, Ning

    2017-12-01

    It is well known that reconstruction problems, as the interdisciplinary subject, have been studied in numerous contexts including statistical physics, information theory and computational biology, to name a few. We consider a 2q-state symmetric model, with two categories of q states in each category, and 3 transition probabilities: the probability to remain in the same state, the probability to change states but remain in the same category, and the probability to change categories. We construct a nonlinear second-order dynamical system based on this model and show that the Kesten-Stigum reconstruction bound is not tight when q ≥ 4.

  16. Formation of tight junctions between neighboring podocytes is an early ultrastructural feature in experimental crescentic glomerulonephritis

    Directory of Open Access Journals (Sweden)

    Succar L

    2016-11-01

    Full Text Available Lena Succar,1 Ross A Boadle,2 David C Harris,1,3 Gopala K Rangan1,3 1Centre for Transplant and Renal Research, The Westmead Institute for Medical Research, The University of Sydney, 2Electron Microscopy Laboratory, Institute of Clinical Pathology and Medical Research, Westmead Hospital, 3Department of Renal Medicine, Westmead Hospital, Western Sydney Local Health District, Westmead, Sydney, NSW, Australia Purpose: In crescentic glomerulonephritis (CGN, the development of cellular bridges between podocytes and parietal epithelial cells (PECs triggers glomerular crescent formation. However, the sequential changes in glomerular ultrastructure in CGN are not well defined. This study investigated the time course of glomerular ultrastructure in experimental CGN. Methods: Transmission electron microscopy (TEM was performed using kidney samples from rats with nephrotoxic serum nephritis (NSN from day 1 to day 14. Morphometric analysis was conducted on randomly selected glomeruli captured on TEM digital images. Results: On day 1 of NSN, there was widespread formation of focal contacts between the cell bodies of neighboring podocytes, and tight junctions were evident at the site of cell-to-cell contact. This was confirmed by the increased expression of the tight junction molecule, zonula occludens-1 (ZO-1, which localized to the points of podocyte cell–cell body contact. On day 2, the interpodocyte distance decreased and the glomerular basement membrane thickness increased. Foot process effacement (FPE was segmental on day 3 and diffuse by day 5, accompanied by the formation of podocyte cellular bridges with Bowman’s capsule, as confirmed by a decrease in podocyte-to-PEC distance. Fibrinoid necrosis and cellular crescents were evident in all glomeruli by days 7 and 14. In vitro, the exposure of podocytes to macrophage-conditioned media altered cellular morphology and caused an intracellular redistribution of ZO-1. Conclusion: The formation of tight

  17. Tight bounds on the size of neural networks for classification problems

    Energy Technology Data Exchange (ETDEWEB)

    Beiu, V. [Los Alamos National Lab., NM (United States); Pauw, T. de [Universite Catholique de Louvain, Louvain-la-Neuve (Belgium). Dept. de Mathematique

    1997-06-01

    This paper relies on the entropy of a data-set (i.e., number-of-bits) to prove tight bounds on the size of neural networks solving a classification problem. First, based on a sequence of geometrical steps, the authors constructively compute an upper bound of O(mn) on the number-of-bits for a given data-set - here m is the number of examples and n is the number of dimensions (i.e., R{sup n}). This result is used further in a nonconstructive way to bound the size of neural networks which correctly classify that data-set.

  18. Accelerating drug discovery through tight integration of expert molecular design and predictive scoring.

    Science.gov (United States)

    Abel, Robert; Mondal, Sayan; Masse, Craig; Greenwood, Jeremy; Harriman, Geraldine; Ashwell, Mark A; Bhat, Sathesh; Wester, Ronald; Frye, Leah; Kapeller, Rosana; Friesner, Richard A

    2017-04-01

    Modeling protein-ligand interactions has been a central goal of computational chemistry for many years. We here review recent progress toward this goal, and highlight the role free energy calculation methods and computational solvent analysis techniques are now having in drug discovery. We further describe recent use of these methodologies to advance two separate drug discovery programs targeting acetyl-CoA carboxylase and tyrosine kinase 2. These examples suggest that tight integration of sophisticated chemistry teams with state-of-the-art computational methods can dramatically improve the efficiency of small molecule drug discovery. Copyright © 2016. Published by Elsevier Ltd.

  19. Tightly focused femtosecond laser pulse in air: from filamentation to breakdown.

    Science.gov (United States)

    Liu, Xiao-Long; Lu, Xin; Liu, Xun; Xi, Ting-Ting; Liu, Feng; Ma, Jing-Long; Zhang, Jie

    2010-12-06

    The propagation of tightly focused femtosecond laser pulse with numerical aperture of 0.12 in air is investigated experimentally. The formation and evolution of the filament bunch are recorded by time-resolved shadowgraph with laser energy from 2.4 mJ to 47 mJ. The distribution of electron density in breakdown area is retrieved using Nomarski interferometer. It is found that intensity clamping during filamentation effect still play a role even under strong external focusing. The electron density in some interaction zones is higher than 3 × 10(19) cm(-3), which indicates that each air molecule there is ionized.

  20. A construction of unimodular equiangular tight frames from resolvable Steiner systems

    Science.gov (United States)

    Jasper, John

    2013-09-01

    An equiangular tight frame (ETF) is an M x N matrix which has orthogonal equal norm rows, equal norm columns, and the inner products of all pairs of columns have the same modulus. In this paper we study ETFs in which all of the entries are unimodular, and in particular pth roots of unity. A new construction of unimodular ETFs based on resolvable Steiner systems is presented. This construction gives many new examples of unimodular ETFs. In particular, an new infinite class of ETFs with entries in f1;-1g is presented.

  1. Incipient localization and tight-binding superconductivity: Tsub(c) calculation

    International Nuclear Information System (INIS)

    Kolley, E.; Kolley, W.

    1984-01-01

    Localization effects on the superconducting transition temperature Tsub(c) are examined in strongly disordered three-dimensional systems. A tight-binding formulation of strong-coupling superconductivity is combined, after configuration averaging, with the self-consistent treatment of Anderson localization developed by Vollhardt and Woelfle. The Coulomb interaction becomes retarded via the joint local local density of states, giving rise to an enhancement of the pseudopotential. Numerical Tsub(c) results as a function of disorder are compared with another theoretical work and experimental values for some high-Tsub(c) materials. (orig.)

  2. Plasmonic resonance scattering from silver nanowire illuminated by tightly focused singular beam.

    Science.gov (United States)

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2010-08-15

    We investigate scattering features of tightly focused singular beams by placing a cylindrical nanowire in the vicinity of a line phase singularity. Applying an illumination wavelength corresponding to silver cylinder plasmonic resonance, we compare the scattering response with that of a perfect conductor. The rigorous modeling employs a 2D version of the Richards-Wolf focusing method and the source model technique. It is found that a cylinder with a plasmonic resonance produces a strong scattering response by deflecting the power flow toward the optical singularity region, where otherwise the power approaches zero.

  3. Vacuum tight sodium resistant compound between ThO2 ceramic and metal

    International Nuclear Information System (INIS)

    Reetz, T.

    A method for evaluating the mechanical tensions for metal/ ceramic joinings was applied to the selection of metal components for a highly vacuum tight, sodium-resistant metal/ThO 2 ceramic solder joining. The metal component selected was the iron--nickel alloy Dilasil which is joined to the ceramic using a nickel-based solder. The wetting of the cearamic could be carried out using the titanium hydride technique or after the formation of a W-cerium layer on the surface of this ceramic. (U.S.)

  4. Vibrationally resolved UV/Vis spectroscopy with time-dependent density functional based tight binding

    OpenAIRE

    Rüger, Robert; Niehaus, Thomas; van Lenthe, Erik; Heine, Thomas; Visscher, Lucas

    2016-01-01

    We report a time-dependent density functional based tight-binding (TD-DFTB) scheme for the calculation of UV/Vis spectra, explicitly taking into account the excitation of nuclear vibrations via the adiabatic Hessian Franck-Condon (AH|FC) method with a harmonic approximation for the nuclear wavefunction. The theory of vibrationally resolved UV/Vis spectroscopy is first summarized from the viewpoint of TD-DFTB. The method is benchmarked against time-dependent density functional theory (TD-DFT) ...

  5. A business process model as a starting point for tight cooperation among organizations

    Directory of Open Access Journals (Sweden)

    O. Mysliveček

    2006-01-01

    Full Text Available Outsourcing and other kinds of tight cooperation among organizations are more and more necessary for success on all markets (markets of high technology products are particularly influenced. Thus it is important for companies to be able to effectively set up all kinds of cooperation. A business process model (BPM is a suitable starting point for this future cooperation. In this paper the process of setting up such cooperation is outlined, as well as why it is important for business success. 

  6. Gas Chromatography.

    Science.gov (United States)

    Cram, Stuart P.; And Others

    1980-01-01

    Selects fundamental developments in theory, methodology, and instrumentation in gas chromatography (GC). A special section reviews GC in the People's Republic of China. Over 1,000 references are cited. (CS)

  7. The Noble Gas Fingerprint in a UK Unconventional Gas Reservoir

    Science.gov (United States)

    McKavney, Rory; Gilfillan, Stuart; Györe, Domokos; Stuart, Fin

    2016-04-01

    In the last decade, there has been an unprecedented expansion in the development of unconventional hydrocarbon resources. Concerns have arisen about the effect of this new industry on groundwater quality, particularly focussing on hydraulic fracturing, the technique used to increase the permeability of the targeted tight shale formations. Methane contamination of groundwater has been documented in areas of gas production1 but conclusively linking this to fugitive emissions from unconventional hydrocarbon production has been controversial2. A lack of baseline measurements taken before drilling, and the equivocal interpretation of geochemical data hamper the determination of possible contamination. Common techniques for "fingerprinting" gas from discrete sources rely on gas composition and isotopic ratios of elements within hydrocarbons (e.g. δ13CCH4), but the original signatures can be masked by biological and gas transport processes. The noble gases (He, Ne, Ar, Kr, Xe) are inert and controlled only by their physical properties. They exist in trace quantities in natural gases and are sourced from 3 isotopically distinct environments (atmosphere, crust and mantle)3. They are decoupled from the biosphere, and provide a separate toolbox to investigate the numerous sources and migration pathways of natural gases, and have found recent utility in the CCS4 and unconventional gas5 industries. Here we present a brief overview of noble gas data obtained from a new coal bed methane (CBM) field, Central Scotland. We show that the high concentration of helium is an ideal fingerprint for tracing fugitive gas migration to a shallow groundwater. The wells show variation in the noble gas signatures that can be attributed to differences in formation water pumping from the coal seams as the field has been explored for future commercial development. Dewatering the seams alters the gas/water ratio and the degree to which noble gases degas from the formation water. Additionally the

  8. Norwegian gas on the European market

    International Nuclear Information System (INIS)

    Noreng, Oeystein

    1999-01-01

    Article. Norsk Hydro's acquisition of Saga has made the organization of Norwegian gas sales a very topical issue. Traditionally, Norwegian gas has been sold on long-term take-or-pay contracts where the sales volume is secured and the price is linked to the prices of other energy carriers, primarily oil. Norway has sold large volumes of gas to the continent and has an increasing share of the market. However, the long-term contracts place most of the price risk on the seller. Although the sale is guaranteed, earnings are low. Statoil, the largest seller of Norwegian gas, has so far earned much more by transporting the gas to the continent than by producing and selling it. The long-term take-or-pay contracts are no longer safe. In Germany, the power market is quickly opening for competition, implying falling prices and lapsing long-term contracts. A similar development is likely to occur in the gas market. From Norwegian quarters there has been little interest in establishing oneself in the gas markets on the continent, which worries the author. However, the traditional contracts will have to be renegotiated so that the prices will reflect the real competition in the market. It is argued that a sensible Norwegian strategy will be to prepare for a new world for gas, not to hold tight to historical positions. It is suggested that old plans to establish a gas transport company, Gassledd, should be revived. Such a company would be subject to the European Gas Directive and would have to admit a third party. It is likely that the Norwegian opposition to liberalization of the European gas market will one day appear poorly thought out, and that defensive considerations have overshadowed new opportunities

  9. Shale Gas and Oil in Germany - Resources and Environmental Impacts

    Science.gov (United States)

    Ladage, Stefan; Blumenberg, Martin; Houben, Georg; Pfunt, Helena; Gestermann, Nicolai; Franke, Dieter; Erbacher, Jochen

    2017-04-01

    In light of the controversial debate on "unconventional" oil and gas resources and the environmental impacts of "fracking", the Federal Institute for Geosciences and Natural Resources (BGR) conducted a comprehensive resource assessment of shale gas and light tight oil in Germany and studied the potential environmental impacts of shale gas development and hydraulic fracturing from a geoscientific perspective. Here, we present our final results (BGR 2016), incorporating the majority of potential shale source rock formations in Germany. Besides shale gas, light tight oil has been assessed. According to our set of criteria - i.e. thermal maturity 0.6-1.2 %vitrinite reflectance (VR; oil) and >1.2 % VR (gas) respectively, organic carbon content > 2%, depth between 500/1000 m and 5000 m as well as a net thickness >20 m - seven potentially generative shale formations were indentified, the most important of them being the Lower Jurassic (Toarcian) Posidonia shale with both shale gas and tight oil potential. The North German basin is by far the most prolific basin. The resource assessment was carried out using a volumetric in-place approach. Variability inherent in the input parameters was accounted for using Monte-Carlo simulations. Technically recoverable resources (TRR) were estimated using recent, production-based recovery factors of North American shale plays and also employing Monte-Carlo simulations. In total, shale gas TRR range between 320 and 2030 bcm and tight oil TRR between 13 and 164 Mio. t in Germany. Tight oil potential is therefore considered minor, whereas the shale gas potential exceeds that of conventional resources by far. Furthermore an overview of numerical transport modelling approaches concerning environmental impacts of the hydraulic fracturing is given. These simulations are based on a representative lithostratigraphy model of the North-German basin, where major shale plays can be expected. Numerical hydrogeological modelling of frac fluid

  10. Tomorrow, gas

    International Nuclear Information System (INIS)

    Icart, Laura; Jean, Pascale; Georget, Cyrille; Schmill, Rafael

    2017-01-01

    This document contains 12 articles notably addressing the importance of natural gas production and supplies in Europe. The themes of the articles are: the advantages of natural gas in the context of energy and environmental policies, energy diversification, energy supply in the local territories, etc.; the position of GrDF, one of the main French natural gas supplier; LPG (butane, propane), a solution which popularity grows in remote areas; the Gaya project (production of renewable gas from dry biomass); a panorama of gas supply routes in Europe; the situation of gas in Europe's energy supply and consumption; the promotion of LNG fuel for maritime and fluvial ships; why the small scale LNG could be the next revolution; presentation of the new 'Honfleur' ferry (using LNG fuel) that will cross the English Channel by 2019; carbon market and the role of ETS for the energy policy in Europe facing the climatic change challenge; presentation of the French 'Climate Plan' that aims to engage France into a carbon neutrality by 2050; presentation of the French policy against air pollution; economic growth, energy, climate: how to square this circle?

  11. Effect of tonicity of nebulised colistin on chest tightness and pulmonary function in adults with cystic fibrosis

    OpenAIRE

    Dodd, M. E.; Abbott, J.; Maddison, J.; Moorcroft, A. J.; Webb, A. K.

    1997-01-01

    BACKGROUND: Inhalation of hypertonic nebulised colistin causes chest tightness and is a reason for discontinuing the treatment. This study examines the relationship of chest tightness and change in lung function in response to the inhalation of a range of tonicities of nebulised colistin and their influence on patients' preference. METHODS: Twenty seven adult patients with cystic fibrosis and a mean forced expiratory volume in one second (FEV1) of 54% predicted (range 24-98) were studie...

  12. Buddly, slug, and annular two-phase flow in tight-lattice subchannels

    Energy Technology Data Exchange (ETDEWEB)

    Prasser, Horst-Michael; Bolesch, Charistian; Cramer, Kerstin; Papadopoulos, Petros; Saxena, Abhishek; Zboray, Robert [ETH Zurich, Dept. of Mechanical and Process Engineering (D-MAVT), Zurich (Switzerland); Ito, Daisuke [Kyoto University, Research Reactor Institute, Osaka (Japan)

    2016-08-15

    An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ) and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI), Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1) a vertical channel modeling a pair of neighboring subchannels; and (2) an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of 16 × 64 measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

  13. Productivity Analysis of Volume Fractured Vertical Well Model in Tight Oil Reservoirs

    Directory of Open Access Journals (Sweden)

    Jiahang Wang

    2017-01-01

    Full Text Available This paper presents a semianalytical model to simulate the productivity of a volume fractured vertical well in tight oil reservoirs. In the proposed model, the reservoir is a composite system which contains two regions. The inner region is described as formation with finite conductivity hydraulic fracture network and the flow in fracture is assumed to be linear, while the outer region is simulated by the classical Warren-Root model where radial flow is applied. The transient rate is calculated, and flow patterns and characteristic flowing periods caused by volume fractured vertical well are analyzed. Combining the calculated results with actual production data at the decline stage shows a good fitting performance. Finally, the effects of some sensitive parameters on the type curves are also analyzed extensively. The results demonstrate that the effect of fracture length is more obvious than that of fracture conductivity on improving production in tight oil reservoirs. When the length and conductivity of main fracture are constant, the contribution of stimulated reservoir volume (SRV to the cumulative oil production is not obvious. When the SRV is constant, the length of fracture should also be increased so as to improve the fracture penetration and well production.

  14. Seismic data interpolation and denoising by learning a tensor tight frame

    International Nuclear Information System (INIS)

    Liu, Lina; Ma, Jianwei; Plonka, Gerlind

    2017-01-01

    Seismic data interpolation and denoising plays a key role in seismic data processing. These problems can be understood as sparse inverse problems, where the desired data are assumed to be sparsely representable within a suitable dictionary. In this paper, we present a new method based on a data-driven tight frame (DDTF) of Kronecker type (KronTF) that avoids the vectorization step and considers the multidimensional structure of data in a tensor-product way. It takes advantage of the structure contained in all different modes (dimensions) simultaneously. In order to overcome the limitations of a usual tensor-product approach we also incorporate data-driven directionality. The complete method is formulated as a sparsity-promoting minimization problem. It includes two main steps. In the first step, a hard thresholding algorithm is used to update the frame coefficients of the data in the dictionary; in the second step, an iterative alternating method is used to update the tight frame (dictionary) in each different mode. The dictionary that is learned in this way contains the principal components in each mode. Furthermore, we apply the proposed KronTF to seismic interpolation and denoising. Examples with synthetic and real seismic data show that the proposed method achieves better results than the traditional projection onto convex sets method based on the Fourier transform and the previous vectorized DDTF methods. In particular, the simple structure of the new frame construction makes it essentially more efficient. (paper)

  15. Ti(IV) and the Siderophore Desferrioxamine B: A Tight Complex Has Biological and Environmental Implications.

    Science.gov (United States)

    Jones, Kayleigh E; Batchler, Kathleen L; Zalouk, Célia; Valentine, Ann M

    2017-02-06

    The siderophore desferrioxamine B (DFOB) binds Ti(IV) tightly and precludes its hydrolytic precipitation under biologically and environmentally relevant conditions. This interaction of DFOB with Ti(IV) is investigated by using spectro-potentiometric and spectro-photometric titrations, mass spectrometry, isothermal titration calorimetry (ITC), and computational modeling. The data from pH 2-10 suggest two one-proton equilibria among three species, with one species predominating below pH 3.5, a second from pH 3.5 to 8, and a third above pH 8. The latter species is prone to slow hydrolytic precipitation. Electrospray mass spectrometry allowed the detection of [Ti(IV) (HDFOB)] 2+ and [Ti(DFOB)] + ; these species were assigned as the pH Ti(IV)-DFOB was determined by using UV/vis-monitored competition with ethylenediaminetetraacetic acid (EDTA). Taking into consideration the available binding constant of Ti(IV) and EDTA, the data reveal values of log β 111 = 41.7, log β 110 = 38.1, and log β 11-1 = 30.1. The former value was supported by ITC, with the transfer of Ti(IV) from EDTA to DFOB determined to be both enthalpically and entropically favorable. Computational methods yielded a model of Ti-DFOB. The physiological and environmental implications of this tight interaction and the potential role of DFOB in solubilizing Ti(IV) are discussed.

  16. Leak-Tight Welding Experience from the Industrial Assembly of the LHC Cryostats at CERN

    CERN Document Server

    Bourcey, N; Chiggiato, P; Limon, P; Mongelluzzo, A; Musso, G; Poncet, A; Parma, V

    2008-01-01

    The assembly of the approximately 1700 LHC main ring cryostats at CERN involved extensive welding of cryogenic lines and vacuum vessels. More than 6 km of welding requiring leak tightness to a rate better than 1.10-9 mbar.l.s-1 on stainless steel and aluminium piping and envelopes was made, essentially by manual welding but also making use of orbital welding machines. In order to fulfil the safety regulations related to pressure vessels and to comply with the leak-tightness requirements of the vacuum systems of the machine, welds were executed according to high qualification standards and following a severe quality assurance plan. Leak detection by He mass spectrometry was extensively used. Neon leak detection was used successfully to locate leaks in the presence of helium backgrounds. This paper presents the quality assurance strategy adopted for welds and leak detection. It presents the statistics of non-conformities on welds and leaks detected throughout the entire production and the advances in the use...

  17. Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells.

    Science.gov (United States)

    Cui, W; Li, L X; Sun, C M; Wen, Y; Zhou, Y; Dong, Y L; Liu, P

    2010-04-01

    The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-alpha) on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell microporous filters and treated with TNF-alpha (10 or 100 ng/mL) for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-alpha treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-alpha decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-alpha did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-alpha increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.

  18. Tumor necrosis factor alpha increases epithelial barrier permeability by disrupting tight junctions in Caco-2 cells

    Directory of Open Access Journals (Sweden)

    W. Cui

    2010-04-01

    Full Text Available The objectives of this study were to determine the effect of tumor necrosis factor alpha (TNF-α on intestinal epithelial cell permeability and the expression of tight junction proteins. Caco-2 cells were plated onto Transwell® microporous filters and treated with TNF-α (10 or 100 ng/mL for 0, 4, 8, 16, or 24 h. The transepithelial electrical resistance and the mucosal-to-serosal flux rates of the established paracellular marker Lucifer yellow were measured in filter-grown monolayers of Caco-2 intestinal cells. The localization and expression of the tight junction protein occludin were detected by immunofluorescence and Western blot analysis, respectively. SYBR-Green-based real-time PCR was used to measure the expression of occludin mRNA. TNF-α treatment produced concentration- and time-dependent decreases in Caco-2 transepithelial resistance and increases in transepithelial permeability to the paracellular marker Lucifer yellow. Western blot results indicated that TNF-α decreased the expression of phosphorylated occludin in detergent-insoluble fractions but did not affect the expression of non-phosphorylated occludin protein. Real-time RT-PCR data showed that TNF-α did not affect the expression of occludin mRNA. Taken together, our data demonstrate that TNF-α increases Caco-2 monolayer permeability, decreases occludin protein expression and disturbs intercellular junctions.

  19. Mobbing and sitting tight at the nest as methods of avoiding brood parasitism.

    Science.gov (United States)

    Rands, Sean A

    2012-04-06

    The arms race between brood parasites and their hosts has led to many different host behaviours for avoiding parasitism. Some of these behaviours are social, and require the presence of conspecifics to work effectively: in response to alarm calls, some species engage in mobbing behaviour where neighbours join nest tenants in attacking and repelling an invading brood parasite. There are risks involved for the neighbours, but it has been demonstrated that social mobbing allows individuals to learn about the presence of brood parasites in the environment, suggesting that social learning is occurring. Here, I consider whether using social signals to alert naive individuals to the presence of brood parasites is a suitable strategy, compared with sitting tight on the nest in response to the signal (which should reduce the chances of being parasitized). I also compare the efficiency of these strategies with the case where individuals fail to change behaviour in response a brood parasite. Using an individual-based simulation model, I demonstrate that both mobbing and sitting tight are effective strategies in response to a signal, and that mobbing is more effective when the chances of being parasitized increase. These results are discussed and compared with known host-brood parasite relationships.

  20. Bubbly, Slug, and Annular Two-Phase Flow in Tight-Lattice Subchannels

    Directory of Open Access Journals (Sweden)

    Horst-Michael Prasser

    2016-08-01

    Full Text Available An overview is given on the work of the Laboratory of Nuclear Energy Systems at ETH, Zurich (ETHZ and of the Laboratory of Thermal Hydraulics at Paul Scherrer Institute (PSI, Switzerland on tight-lattice bundles. Two-phase flow in subchannels of a tight triangular lattice was studied experimentally and by computational fluid dynamics simulations. Two adiabatic facilities were used: (1 a vertical channel modeling a pair of neighboring subchannels; and (2 an arrangement of four subchannels with one subchannel in the center. The first geometry was equipped with two electrical film sensors placed on opposing rod surfaces forming the subchannel gap. They recorded 2D liquid film thickness distributions on a domain of 16 × 64 measuring points each, with a time resolution of 10 kHz. In the bubbly and slug flow regime, information on the bubble size, shape, and velocity and the residual liquid film thickness underneath the bubbles were obtained. The second channel was investigated using cold neutron tomography, which allowed the measurement of average liquid film profiles showing the effect of spacer grids with vanes. The results were reproduced by large eddy simulation + volume of fluid. In the outlook, a novel nonadiabatic subchannel experiment is introduced that can be driven to steady-state dryout. A refrigerant is heated by a heavy water circuit, which allows the application of cold neutron tomography.

  1. Relationship between tightness of the posterior muscles of the lower limb and plantar fasciitis.

    Science.gov (United States)

    Bolívar, Yolanda Aranda; Munuera, Pedro V; Padillo, Juan Polo

    2013-01-01

    The aim of this study was to determine whether tightness of the posterior muscles of the lower extremity was associated with plantar fasciitis. A total of 100 lower limbs of 100 subjects, 50 with plantar fasciitis and 50 matching controls were recruited. Hamstring and calf muscles were evaluated through the straight leg elevation test, popliteal angle test, and ankle dorsiflexion (knee extended and with the knee flexed). All variables were compared between the 2 groups. In addition, ROC curves, sensitivity, and specificity of the muscle contraction tests were also calculated to determine their potential predictive powers. Differences between the 2 groups for the tests used to assess muscular shortening were significant (P muscles of the lower limb was present in the plantar fasciitis patients, but not in the unaffected participants. The results of this study suggest that therapists who are going to employ a stretching protocol for treatment of plantar fasciitis should look for both hamstring as well as triceps surae tightness. Stretching exercise programs could be recommended for treatment of plantar fasciitis, focusing on stretching the triceps surae and hamstrings, apart from an adequate tissue-specific plantar fascia-stretching protocol. Level III, case control study.

  2. Giardia disrupts the arrangement of tight, adherens and desmosomal junction proteins of intestinal cells.

    Science.gov (United States)

    Maia-Brigagão, C; Morgado-Díaz, J A; De Souza, W

    2012-06-01

    Giardia duodenalis is a parasitic protozoan that causes diarrhea and other symptoms which together constitute a disease known as giardiasis. Although the disease has been well defined, the mechanisms involving the establishment of the infection have not yet been fully elucidated. In this study, we show that after 24h of interaction between parasites and intestinal Caco-2 cells, there was an alteration of the paracellular permeability, as observed by an approximate 42% of reduction in the transepithelial electrical resistance and permeation to ruthenium red, which was concomitant with ultrastructural changes. Nevertheless, epithelium viability was not affected. We also demonstrate that there was no change in expression of junctional proteins (tight and adherens) but that the distribution of these proteins in Caco-2 cells after parasite adhesion was significantly altered, as observed via laser scanning confocal microscopy 3D reconstruction. The present work shows that adhesion of Giardia duodenalis trophozoites to intestinal cells in vitro induces disturbances of the tight, adherens and desmosomal junctions. Copyright © 2011 Elsevier Ireland Ltd. All rights reserved.

  3. The band gap of II-Vi ternary alloys in a tight-binding description

    Energy Technology Data Exchange (ETDEWEB)

    Olguin, Daniel; Blanquero, Rafael [Instituto Politecnico Nacional, Mexico, D.F (Mexico); De Coss, Romeo [Instituto Politecnico Nacional, Yucatan (Mexico)

    2001-02-01

    We present tight-binding calculations for the band gap of II-Vi pseudobinary ternary alloys. We use an sp{sup 3} s* tight-binding Hamiltonian which include spin-orbit coupling. The band gap composition dependence is calculated using a extended version of the virtual crystal approximation, which introduce an empirical correction factor that takes into account the non-linear dependence of the band gap with the composition. The results compare quite well with the experimental data, both for the ternary alloys with wide band gap and for the narrow band gap ones. [Spanish] Presentamos el calculo de la banda de energia prohibida de aleaciones ternarias de compuestos II-VI. El calculo, que incluye interaccion espin-orbita, se hace con el metodo de enlace fuerte, utilizando una base ortogonal de cinco orbitales atomicos por atomo (sp{sup 3} s*), en conjunto con la aproximacion del cristal virtual. En la aproximacion del cristal virtual, incluimos un factor de correccion que toma en cuenta la no linealidad de la banda de energia prohibida como funcion de la concentracion. Con esta correccion nuestros resultados reproducen aceptablemente los datos experimentales hallados en la literatura.

  4. Tight-binding density functional theory: an approximate Kohn-Sham DFT scheme.

    Science.gov (United States)

    Seifert, G

    2007-07-05

    The DFTB method is an approximate KS-DFT scheme with an LCAO representation of the KS orbitals, which can be derived within a variational treatment of an approximate KS energy functional. But it may also be related to cellular Wigner-Seitz methods and to the Harris functional. It is an approximate method, but it avoids any empirical parametrization by calculating the Hamiltonian and overlap matrices out of DFT-derived local orbitals (atomic orbitals, AO's). The method includes ab initio concepts in relating the Kohn-Sham orbitals of the atomic configuration to a minimal basis of the localized atomic valence orbitals of the atoms. Consistent with this approximation, the Hamiltonian matrix elements can strictly be restricted to a two-center representation. Taking advantage of the compensation of the so-called "double counting terms" and the nuclear repulsion energy in the DFT total energy expression, the energy may be approximated as a sum of the occupied KS single-particle energies and a repulsive energy, which can be obtained from DFT calculations in properly chosen reference systems. This relates the method to common standard "tight-binding" (TB) schemes, as they are well-known in solid-state physics. This approach defines the density-functional tight-binding (DFTB) method in its original (non-self-consistent) version.

  5. Analysis of stress sensitivity and its influence on oil productionfrom tight reservoirs

    Energy Technology Data Exchange (ETDEWEB)

    Lei, Qun; Xiong, Wei; Yuan, Cui; Wu, Yu-Shu

    2007-08-28

    This paper presents a study of the relationship betweenpermeability and effective stress in tight petroleum reservoirformations. Specifically, a quantitative method is developed to describethe correlation between permeability and effective stress, a method basedon the original in situ reservoir effective stress rather than ondecreased effective stress during development. The experimental resultsshow that the relationship between intrinsic permeability and effectivestress in reservoirs in general follows a quadratic polynomial functionalform, found to best capture how effective stress influences formationpermeability. In addition, this experimental study reveals that changesin formation permeability, caused by both elastic and plasticdeformation, are permanent and irreversible. Related pore-deformationtests using electronic microscope scanning and constant-rate mercuryinjection techniques show that while stress variation generally has smallimpact onrock porosity, the size and shape of pore throats have asignificant impact on permeability-stress sensitivity. Based on the testresults and theoretical analyses, we believe that there exists a cone ofpressure depression in the area near production within suchstress-sensitive tight reservoirs, leading to a low-permeability zone,and that well production will decrease under the influence of stresssensitivity.

  6. Tight-Binding simulations of InAs/GaAs quantum dots; Tight-Binding Simulationen von InAs/GaAs Quantenpunkten

    Energy Technology Data Exchange (ETDEWEB)

    Kleinsorge, Alexander

    2008-06-23

    For several years, the technological potential of self-organized grown quantum dots (QD) has been known. Their usage as an effective light source or memory requires the precise prediction of their electronic properties. Hence, this report will study InAs quantum dots at GaAs substrate. After relaxing the atomic positions with a many body potential of Abell-Tersoff type, I calculated the electronic structure using the Tight-Binding method which is reasonable for large systems. During the investigation of wavefunctions depend on the shape, size and temperature, the impact of strain showed up as the main reason for the p-splitting. Typically flat QDs (relative to lateral dimensions) are grown, therefore the energy of bound states depends mostly on their height. The crystal's orientation had a strong impact on the wavefunctions. Moreover, the understanding of STS experiments, which inspected the connection between shape and wavefunction, is better now. Because of the possible simultaneous occupation of semiconductor quantum dots with an electron and a hole, there is a dipole moment of the exciton (due to their different behaviour inside the QD). This is a further experimental access to inner details of the QD. I ascertained the interplay of composition profile and dipole moment. The force caused by additional potentials (piezoelectricity, outer homogeneous and inhomogeneous electrical fields) was also an subject of my inquiries. To conclude, I executed kMC simulations, to better apprehend the annealing experiments. I was able to explain the narrowing of the PL peak width better. Furthermore I showed a ramification of the strain field to the diffusion development (and the following electronic properties). (orig.)

  7. Chlorine Gas Inhalation

    Science.gov (United States)

    White, Carl W.; Martin, James G.

    2010-01-01

    Humans can come into contact with chlorine gas during short-term, high-level exposures due to traffic or rail accidents, spills, or other disasters. By contrast, workplace and public (swimming pools, etc.) exposures are more frequently long-term, low-level exposures, occasionally punctuated by unintentional transient increases. Acute exposures can result in symptoms of acute airway obstruction including wheezing, cough, chest tightness, and/or dyspnea. These findings are fairly nonspecific, and might be present after exposures to a number of inhaled chemical irritants. Clinical signs, including hypoxemia, wheezes, rales, and/or abnormal chest radiographs may be present. More severely affected individuals may suffer acute lung injury (ALI) and/or acute respiratory distress syndrome (ARDS). Up to 1% of exposed individuals die. Humidified oxygen and inhaled β-adrenergic agents are appropriate therapies for victims with respiratory symptoms while assessments are underway. Inhaled bicarbonate and systemic or inhaled glucocorticoids also have been reported anecdotally to be beneficial. Chronic sequelae may include increased airways reactivity, which tends to diminish over time. Airways hyperreactivity may be more of a problem among those survivors that are older, have smoked, and/or have pre-existing chronic lung disease. Individuals suffering from irritant-induced asthma (IIA) due to workplace exposures to chlorine also tend to have similar characteristics, such as airways hyperresponsiveness to methacholine, and to be older and to have smoked. Other workplace studies, however, have indicated that workers exposed to chlorine dioxide/sulfur dioxide have tended to have increased risk for chronic bronchitis and/or recurrent wheezing attacks (one or more episodes) but not asthma, while those exposed to ozone have a greater incidence of asthma. Specific biomarkers for acute and chronic exposures to chlorine gas are currently lacking. Animal models for chlorine gas

  8. Canadian natural gas : market review and outlook

    International Nuclear Information System (INIS)

    2001-01-01

    This annual working paper provides summaries of trends within the North American natural gas industry and also reviews Canadian gas exports. It is designed to promote dialogue between industry and the government and to obtain feedback on natural gas issues. The main section of the report consists of graphs, with limited text comments on the side. It provides a structured look at supply and demand for the year 2000 as well as for the near term (2001) and long-term (2010). The sources of information included private consultants, industry associations and federal agencies in Canada and the United States. It was shown that gas demand had grown steadily in North America since 1997, at about 2.5 per cent annually, and then fell 3.4 per cent in 1998 and remained low in 1999, below 1997 demand. This was due mainly to mild winters. In 2000, the demand for natural gas increased again to 5 per cent as a result of a colder winter and increased gas use for power generation. The report also stated that the combination of various factors including low storage balances due to previously low drilling years and high oil prices, were responsible for natural gas price increases in 2000. The tight supply/demand balance was exacerbated by restraints in pipeline capacity. Producers and pipeline groups are now looking seriously at developing the large gas deposits in Alaska and the Mackenzie Delta which were previously considered to be uneconomic. It was noted that in the near term, storage must be rebuilt to normal levels. Storage balances will be a good indicator of the relative strengths of gas production and demand growth. It was forecasted that Canada to U.S. gas exports should continue to increase in 2001 as a large new export pipeline was completed in 2000, but there is considerable uncertainty for the medium to longer-term. refs., tabs., figs

  9. Enhanced oil recovery by nitrogen and carbon dioxide injection followed by low salinity water flooding for tight carbonate reservoir: experimental approach

    Science.gov (United States)

    Georges Lwisa, Essa; Abdulkhalek, Ashrakat R.

    2018-03-01

    Enhanced Oil Recovery techniques are one of the top priorities of technology development in petroleum industries nowadays due to the increase in demand for oil and gas which cannot be equalized by the primary production or secondary production methods. The main function of EOR process is to displace oil to the production wells by the injection of different fluids to supplement the natural energy present in the reservoir. Moreover, these injecting fluids can also help in the alterations of the properties of the reservoir like lowering the IFTs, wettability alteration, a change in pH value, emulsion formation, clay migration and oil viscosity reduction. The objective of this experiment is to investigate the residual oil recovery by combining the effects of gas injection followed by low salinity water injection for low permeability reservoirs. This is done by a series of flooding tests on selected tight carbonate core samples taken from Zakuum oil field in Abu Dhabi by using firstly low salinity water as the base case and nitrogen & CO2injection followed by low salinity water flooding at reservoir conditions of pressure and temperature. The experimental results revealed that a significant improvement of the oil recovery is achieved by the nitrogen injection followed by the low salinity water flooding with a recovery factor of approximately 24% of the residual oil.

  10. Study of the low-frequency dispersion of permittivity and resistivity in tight rocks

    Science.gov (United States)

    Liu, Hongqi; Jie, Tian; Li, Bo; Youming, Deng; Chunning, Qiu

    2017-08-01

    The road to understanding the frequency dispersion (relaxation) of permittivity and resistivity in tight rocks remains relatively uncharted. Our team from Da'anzhai Group, Jurassic formation, Sichuan Basin carried out practical research to explore this phenomenon. The research was conducted under laboratory conditions for a selection of low frequencies, with ranges between 0.1 Hz to 1 kHz. Our research has shown that, although both the permittivity and resistivity decrease as the frequency increases, the two individual metrics display different behaviours when compared with each other. While the degree of resistivity variation is minimal, to the point that it is redundant, the permittivity, on the other hand, demonstrates something that is scientifically noteworthy. Permittivity has a distinctive dispersion degree across the entire sample of frequencies and the difference between the minimum and maximum frequencies is several orders of magnitude. An additional, and unexpected, learning from our research is that the level of frequency dispersion increases as the water saturation and concentration increases. In this paper, a collection of equations has been formulated to describe this relationship. These equations particularly shed light on the areas of rock porosity and saturation. They also show that the degree of frequency dispersion of permittivity or resistivity can be used as a function of water saturation and concentration. Two new variables are introduced here, DR and DC, to demonstrate the relaxation law quantitatively. In our practical research, we have characterised the relationship between the saturation and concentration with dielectric relaxation, using three different concentrations of DR and DC and five different saturations of NaCl solution. In difference to conventional Archie's multiple experimental parameters, we have established a new formula to derive the saturation from Rp and Cp, or from DR and DC directly. Two important frequencies were also

  11. Relationship of tightly bound ADP and ATP to control and catalysis by chloroplast ATP synthase

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, J.; Xue, Z.; Du, Z.; Melese, T.; Boyer, P.D.

    1988-07-12

    Whether the tightly bound ADP that can cause a pronounced inhibition of ATP hydrolysis by the chloroplast ATP synthase and F/sub 1/ ATPase (CF/sub 1/) is bound at catalytic sites or at noncatalytic regulatory sites or both has been uncertain. The authors have used photolabeling by 2-azido-ATP and 2-azido-ADP to ascertain the location, with Mg/sup 2 +/ activation, of tightly bound ADP (a) that inhibits the hydrolysis of ATP by chloroplast ATP synthase, (b) that can result in an inhibited form of CF/sub 1/ that slowly regains activity during ATP hydrolysis, and (c) that arises when low concentrations of ADP markedly inhibit the hydrolysis of GTP by CF/sub 1/. The data show that in all instances the inhibition is associated with ADP binding without inorganic phosphate (P/sub i/) at catalytic sites. After photophosphorylation of ADP or 2-azido-ADP with (/sup 32/P)P/sub i/, similar amounts of the corresponding triphosphates are present on washed thylakoid membranes. Trials with appropriately labeled substrates show that a small portion of the tightly bound 2-azido-ATP gives rise to covalent labeling with an ATP moiety at noncatalytic sites but that most of the bound 2-azido-ATP gives rise to covalent labeling with an ATP moiety at noncatalytic sites but that most of the bound 2-azido-ATP gives rise to covalent labeling by an ADP moiety at a catalytic site. They also report the occurrence of a 1-2-min delay in the onset of the Mg/sup 2 +/-induced inhibition after addition of CF/sub 1/ to solutions containing Mg/sup 2 +/ and ATP, and that this delay is not associated with the filling of noncatalytic sites. A rapid burst of P/sub i/ formation is followed by a much lower, constant steady-state rate. The burst is not observed with GTP as a substrate or with Ca/sup 2 +/ as the activating cation.

  12. Improved Helicopter Rotor Performance Prediction through Loose and Tight CFD/CSD Coupling

    Science.gov (United States)

    Ickes, Jacob C.

    Helicopters and other Vertical Take-Off or Landing (VTOL) vehicles exhibit an interesting combination of structural dynamic and aerodynamic phenomena which together drive the rotor performance. The combination of factors involved make simulating the rotor a challenging and multidisciplinary effort, and one which is still an active area of interest in the industry because of the money and time it could save during design. Modern tools allow the prediction of rotorcraft physics from first principles. Analysis of the rotor system with this level of accuracy provides the understanding necessary to improve its performance. There has historically been a divide between the comprehensive codes which perform aeroelastic rotor simulations using simplified aerodynamic models, and the very computationally intensive Navier-Stokes Computational Fluid Dynamics (CFD) solvers. As computer resources become more available, efforts have been made to replace the simplified aerodynamics of the comprehensive codes with the more accurate results from a CFD code. The objective of this work is to perform aeroelastic rotorcraft analysis using first-principles simulations for both fluids and structural predictions using tools available at the University of Toledo. Two separate codes are coupled together in both loose coupling (data exchange on a periodic interval) and tight coupling (data exchange each time step) schemes. To allow the coupling to be carried out in a reliable and efficient way, a Fluid-Structure Interaction code was developed which automatically performs primary functions of loose and tight coupling procedures. Flow phenomena such as transonics, dynamic stall, locally reversed flow on a blade, and Blade-Vortex Interaction (BVI) were simulated in this work. Results of the analysis show aerodynamic load improvement due to the inclusion of the CFD-based airloads in the structural dynamics analysis of the Computational Structural Dynamics (CSD) code. Improvements came in the form

  13. Effect of frequency of static stretching on flexibility, hamstring tightness and electromyographic activity

    Directory of Open Access Journals (Sweden)

    A.P. Marques

    2009-10-01

    Full Text Available We compared the effect of the number of weekly repetitions of a static stretching program on the flexibility, hamstring tightness and electromyographic activity of the hamstring and of the triceps surae muscles. Thirty-one healthy subjects with hamstring tightness, defined as the inability to perform total knee extension, and shortened triceps surae, defined by a tibiotarsal angle wider than 90° during trunk flexion, were divided into three groups: G1 performed the stretching exercises once a week; G2, three times a week, and G3, five times a week. The parameters were determined before and after the stretching program. Flexibility improved in all groups after intervention, from 7.65 ± 10.38 to 3.67 ± 12.08 in G1, from 10.73 ± 12.07 to 0.77 ± 10.45 in G2, and from 14.20 ± 10.75 to 6.85 ± 12.19 cm in G3 (P < 0.05 for all comparisons. The increase in flexibility was higher in G2 than in G1 (P = 0.018, while G2 and G3 showed no significant difference (G1: 4 ± 2.17, G2: 10 ± 5.27; G3: 7.5 ± 4.77 cm. Hamstring tightness improved in all groups, from 37.90 ± 6.44 to 29 ± 11.65 in G1, from 39.82 ± 9.63 to 21.91 ± 8.40 in G2, and from 37.20 ± 6.63 to 26.10 ± 5.72° in G3 (P < 0.05 for all comparisons. During stretching, a statistically significant difference was observed in electromyographic activity of biceps femoris muscle between G1 and G3 (P = 0.048 and G2 and G3 (P = 0.0009. No significant differences were found in electromyographic activity during maximal isometric contraction. Stretching exercises performed three times a week were sufficient to improve flexibility and range of motion compared to subjects exercising once a week, with results similar to those of subjects who exercised five times a week.

  14. Effect of retrograde gas condensate in low permeability natural gas reservoir; Efeito da condensacao retrograda em reservatorios de gas natural com baixa permeabilidade

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Paulo Lee K.C. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica; Ligero, Eliana L.; Schiozer, Denis J. [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Engenharia de Petroleo

    2008-07-01

    Most of Brazilian gas fields are low-permeability or tight sandstone reservoirs and some of them should be gas condensate reservoir. In this type of natural gas reservoir, part of the gaseous hydrocarbon mixture is condensate and the liquid hydrocarbon accumulates near the well bore that causes the loss of productivity. The liquid hydrocarbon formation inside the reservoir should be well understood such as the knowledge of the variables that causes the condensate formation and its importance in the natural gas production. This work had as goal to better understanding the effect of condensate accumulation near a producer well. The influence of the porosity and the absolute permeability in the gas production was studied in three distinct gas reservoirs: a dry gas reservoir and two gas condensate reservoirs. The refinement of the simulation grid near the producer well was also investigated. The choice of simulation model was shown to be very important in the simulation of gas condensate reservoirs. The porosity was the little relevance in the gas production and in the liquid hydrocarbon formation; otherwise the permeability was very relevant. (author)

  15. Conditioned medium from LS 174T goblet cells treated with oxyresveratrol strengthens tight junctions in Caco-2 cells.

    Science.gov (United States)

    Hwang, Dahyun; Jo, HyunA; Hwang, Seonwook; Kim, Jeong-Keun; Kim, In-Ho; Lim, Young-Hee

    2017-01-01

    Strengthening of intestinal tight junctions provides an effective barrier from the external environment. Goblet cell-derived trefoil factor 3 (TFF3) increases transepithelial resistance by upregulating the expression of tight junction proteins. Oxyresveratrol (OXY) is a hydroxyl-substituted stilbene found in the roots, leaves, stems, and fruit of many plants and known to have various biological activities. In this study, we investigated the strengthening effect of OXY on intestinal tight junctions through stimulation of TFF production in goblet cells. We prepared conditioned medium from LS 174T goblet cells treated with OXY (GCO-CM) and investigated the effect of GCO-CM on strengthening tight junctions of Caco-2 cells. The mRNA and protein expression levels of major tight junction components (claudin-1, occludin, and ZO-1) were measured by quantitative real-time PCR and western blotting, respectively. Transepithelial electric resistance (TEER) was measured using an ohm/V meter. Monolayer permeability was evaluated by paracellular transport of fluorescein isothiocyanate-dextran. OXY showed a strong antioxidant activity. It significantly increased the expression level of TFF3 in LS 174T goblet cells. GCO-CM prepared by treatment with 2.5, 5, and 10μg/ml OXY did not show cytotoxicity in Caco-2 cells. GCO-CM increased the mRNA and protein expression levels of claudin-1, occludin, and ZO-1. It also significantly increased tight junction integrity and reduced permeability in a dose-dependent manner. OXY stimulates the expression of TFF3 in goblet cells, which might increase the integrity of the intestinal tight junction barrier. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  16. Petri Net-Based Model of Helicobacter pylori Mediated Disruption of Tight Junction Proteins in Stomach Lining during Gastric Carcinoma

    Directory of Open Access Journals (Sweden)

    Anam Naz

    2017-09-01

    Full Text Available Tight junctions help prevent the passage of digestive enzymes and microorganisms through the space between adjacent epithelial cells lining. However, Helicobacter pylori encoded virulence factors negatively regulate these tight junctions and contribute to dysfunction of gastric mucosa. Here, we have predicted the regulation of important tight junction proteins, such as Zonula occludens-1, Claudin-2 and Connexin32 in the presence of pathogenic proteins. Molecular events such as post translational modifications and crosstalk between phosphorylation, O-glycosylation, palmitoylation and methylation are explored which may compromise the integrity of these tight junction proteins. Furthermore, the signaling pathways disrupted by dysregulated kinases, proteins and post-translational modifications are reviewed to design an abstracted computational model showing the situation-dependent dynamic behaviors of these biological processes and entities. A qualitative hybrid Petri Net model is therefore constructed showing the altered host pathways in the presence of virulence factor cytotoxin-associated gene A, leading to the disruption of tight junction proteins. The model is qualitative logic-based, which does not depend on any kinetic parameter and quantitative data and depends on knowledge derived from experiments. The designed model provides insights into the tight junction disruption and disease progression. Model is then verified by the available experimental data, nevertheless formal in vitro experimentation is a promising way to ensure its validation. The major findings propose that H. pylori activated kinases are responsible to trigger specific post translational modifications within tight junction proteins, at specific sites. These modifications may favor alterations in gastric barrier and provide a route to bacterial invasion into host cells.

  17. Examinations for leak tightness of actively cooled components in ITER and fusion devices

    Science.gov (United States)

    Hirai, T.; Barabash, V.; Carrat, R.; Chappuis, Ph; Durocher, A.; Escourbiac, F.; Merola, M.; Raffray, R.; Worth, L.; Boscary, J.; Chantant, M.; Chuilon, B.; Guilhem, D.; Hatchressian, J.-C.; Hong, S. H.; Kim, K. M.; Masuzaki, S.; Mogaki, K.; Nicolai, D.; Wilson, D.; Yao, D.

    2017-12-01

    Any leak in one of the ITER actively cooled components would cause significant consequences for machine operations; therefore, the risk of leak must be minimized as much as possible. In this paper, the strategy of examination to ensure leak tightness of the ITER internal components (i.e. examination of base materials, vacuum boundary joints and final components) and the hydraulic parameters for ITER internal components are summarized. The experiences of component tests, especially hot helium leak tests in recent fusion devices, were reviewed and the parameters were discussed. Through these experiences, it was confirmed that the hot He leak test was effective to detect small leak paths which were not always possible to detect by volumetric examination due to limited spatial resolution.

  18. Perspectives from ab-initio and tight-binding: Applications to transition metal compounds and superlattices

    Science.gov (United States)

    Venkataraman, Vijay Shankar

    The experimental and theoretical study of transition metal compounds have occupied condensed matter physicists for the best part of the last century. The rich variety of physical behaviour exhibited by these compounds owes its origin to the subtle balance of the energy scales at play for the d orbitals. In this thesis, we study three different systems comprised of transition metal atoms from the third, the fourth, and the fifth group of the periodic table using a combination of ab-initio density functional theory (DFT) computations and effective tight-binding models for the electronic properties. We first consider the electronic properties of artificially fabricated perovskite superlattices of the form [(SrIrO3)m / SrTiO3] with integer m denoting the number of layers of SrIrO3. After discussing the results of experiments undertaken by our collaborators, we present the results of our DFT calculations and build tight-binding models for the m = 1 and m = 2 superlattices. The active ingredient is found to be the 5d orbitals with significant spin-orbit coupling. We then study the energies of magnetic ground states within DFT and compare and contrast our results with those obtained for the bulk Ruddlesden-Popper iridates. Together with experimental measurements, our results suggest that these superlattices are an exciting venue to probe the magnetism and metal-insulator transitions that occur from the intricate balance of the spin-orbit coupling and electron interactions, as has been reported for their bulk counterparts. Next, we consider alpha-RuCl3, a honeycomb lattice compound. We first show using DFT calculations in conjunction with experiments performed by our collaborators, how spin-orbit coupling in the 4d orbitals of Ru is essential to understand the insulating state realized in this compound. Then, in the latter half of the chapter, we study the magnetic ground states of a two-dimensional analogue of alpha-RuCl3 in weak and strong-coupling regimes obtained from

  19. Virtual crystal description of III–V semiconductor alloys in the tight binding approach

    International Nuclear Information System (INIS)

    Nestoklon, M O; Benchamekh, R; Voisin, P

    2016-01-01

    We propose a simple and effective approach to construct the empirical tight-binding parameters of ternary alloys in the virtual crystal approximation. This combines a new, compact formulation of the strain parameters and a linear interpolation of the Hamiltonians of binary materials strained to the alloy equilibrium lattice parameter . We show that it is possible to obtain a perfect description of the bandgap bowing of ternary alloys in the InGaAsSb family of materials. Furthermore, this approach is in a good agreement with supercell calculations using the same set of parameters. This scheme opens a way for atomistic modeling of alloy-based quantum wells and quantum wires without extensive supercell calculations. (paper)

  20. Multilayered black phosphorus: From a tight-binding to a continuum description

    Science.gov (United States)

    de Sousa, D. J. P.; de Castro, L. V.; da Costa, D. R.; Pereira, J. Milton; Low, Tony

    2017-10-01

    We investigate the electronic properties of N -layer black phosphorus by means of an analytical method based on a recently proposed tight-binding Hamiltonian involving 14 hopping parameters. The method provides simple and accurate general expressions for the Hamiltonian of N -layer phosphorene, which are suitable for the study of electronic transport and optical properties of such systems, and the results show the features that emerge as the number of layers increases. In addition, we show that the N -layer problem can be translated into N effective monolayer problems in the long wavelength approximation and, within this analytical picture, we obtain expressions for the energy gap and the effective masses for electrons and holes along the N -layer black phosphorus plane directions as a function of the number of layers, as well as for the Landau levels as a function of perpendicular magnetic field.

  1. Assessment of the Density Functional Tight Binding Method for Protic Ionic Liquids.

    Science.gov (United States)

    Addicoat, Matthew A; Stefanovic, Ryan; Webber, Grant B; Atkin, Rob; Page, Alister J

    2014-10-14

    Density functional tight binding (DFTB), which is ∼100-1000 times faster than full density functional theory (DFT), has been used to simulate the structure and properties of protic ionic liquid (IL) ions, clusters of ions and the bulk liquid. Proton affinities for a wide range of IL cations and anions determined using DFTB generally reproduce G3B3 values to within 5-10 kcal/mol. The structures and thermodynamic stabilities of n -alkyl ammonium nitrate clusters (up to 450 quantum chemical atoms) predicted with DFTB are in excellent agreement with those determined using DFT. The IL bulk structure simulated using DFTB with periodic boundary conditions is in excellent agreement with published neutron diffraction data.

  2. Energy spectrum of two-dimensional tight-binding electrons in a spatially varying magnetic field

    International Nuclear Information System (INIS)

    Oh, G.Y.; Lee, M.H.

    1996-01-01

    The electronic energy spectrum of a two-dimensional lattice in a spatially varying magnetic field is studied within the framework of the tight-binding model by using the scheme of the transfer matrix. It is found that, in comparison with the case of a uniform magnetic field, the energy spectrum exhibits more complicated behavior; band broadening (or gap closing) and band splitting (or gap opening) occur depending on characteristic parameters of the lattice. The origin of these phenomena lies in the existence of direct touching and indirect overlapping between neighboring subbands. Dependence of direct touching and indirect overlapping, and thus the electronic band structure together with the density of states, on characteristic parameters of the lattice is elucidated in detail. copyright 1996 The American Physical Society

  3. Physics Colloquium - Tight-binding in a new light: Photons in optical lattices

    CERN Multimedia

    Ecole de Physique - Université de Genève

    2011-01-01

    Geneva University Physics Department 24, Quai Ernest Ansermet CH-1211 Geneva 4   Lundi 21 mars 2011, 17h00 Ecole de Physique, Auditoire Stueckelberg Tight-binding in a new light: Photons in optical lattices Dr. Niels Madsen Department of Physics, Swansea University, Singleton Park, Swansea, United Kingdom   Antihydrogen, the bound state of an antiproton and a positron, has been produced at low energies at CERN (the European Organization for Nuclear Research) since 2002. Antihydrogen is of interest for use in a precision test of nature's fundamental symmetries. The charge conjugation/parity/time reversal (CPT) theorem, a crucial part of the foundation of the standard model of elementary particles and interactions, demands that hydrogen and antihydrogen have the same spectrum. Given the current experimental precision of measurements on the hydrogen atom, subjecting antihydrogen to rigorous spectroscopic examination would constitute a compelling, model-independent test of CPT. Antihydrogen co...

  4. Tight finite-key analysis for passive decoy-state quantum key distribution under general attacks

    Science.gov (United States)

    Zhou, Chun; Bao, Wan-Su; Li, Hong-Wei; Wang, Yang; Li, Yuan; Yin, Zhen-Qiang; Chen, Wei; Han, Zheng-Fu

    2014-05-01

    For quantum key distribution (QKD) using spontaneous parametric-down-conversion sources (SPDCSs), the passive decoy-state protocol has been proved to be efficiently close to the theoretical limit of an infinite decoy-state protocol. In this paper, we apply a tight finite-key analysis for the passive decoy-state QKD using SPDCSs. Combining the security bound based on the uncertainty principle with the passive decoy-state protocol, a concise and stringent formula for calculating the key generation rate for QKD using SPDCSs is presented. The simulation shows that the secure distance under our formula can reach up to 182 km when the number of sifted data is 1010. Our results also indicate that, under the same deviation of statistical fluctuation due to finite-size effects, the passive decoy-state QKD with SPDCSs can perform as well as the active decoy-state QKD with a weak coherent source.

  5. CFD analysis of coolant channel geometries for a tightly packed fuel rods assembly at subcritical pressure

    International Nuclear Information System (INIS)

    Guo, Rui; Oka, Yoshiaki

    2015-01-01

    Highlights: • Three coolant channel geometries are proposed for high breeding LWRs. • Thermal hydraulic performance of coolant channel geometries are analyzed. • Design ranges of PWRs and BWRs with proposed geometries are designated. • One type of geometry (Geometry B) is proved to be superior to the others. - Abstract: This paper analyzes the thermal hydraulic performance of channels with different cross sectional geometries, which were adopted by tightly packed fuel rods assembly for high breeding at operating pressure of PWR and BWR. The calculations were carried out to assess the geometrical effect of coolant channels on thermal-hydraulic parameters by using a CFD code STAR-CCM+. It is found that one type of channel geometry (geometry B) is superior to others because of broad design area of power, cladding temperature and pressure drop

  6. Tight-binding model study of the evolution of G-peak in monolayer graphene

    Science.gov (United States)

    Sahu, Sivabrata; Panda, S. K.; Rout, G. C.

    2017-05-01

    We propose here a tight-binding model with nearest-neighbor hopping integral in presence of one site doping. Phonon is coupled to the hopping integral with dimensionless coupling g in presence of bare phonon vibrational energy in graphene plane. Phonon Green's function Dq ,q(ω ) is calculated from the total Hamiltonian by using Zubarev's Green's function technique and the phonon self-energy is evaluated from the pure electronic Hamiltonian. The Raman spectral density function (SDF) is calculated from the formula S D F =-2 π I m [Dq ,q(ω +i η )] , where η is the small spectral width. The calculated Raman spectra exhibits high energy and highly intense G peak, phonon momentum transfer energy peak and a lower energy anomalous peak. The evolution of these peaks is investigated by varying the model parameters of the graphene system.

  7. Dealing with Tight Couplings and Multiple Interactions in Complex Technological Systems

    DEFF Research Database (Denmark)

    Aanestad, M.; Jensen, Tina Blegind; Grisot, M.

    In this paper we discuss the challenges of dealing with interdependencies in complex assemblages of heterogeneous and interconnected information systems (IS), which we conceptualize as organizationwide information infrastructures. We draw on Perrow's studies of complex technological systems, where...... couplings between information systems, actors, and work practices in the hospital environment. The paper's main focus is on describing what it entails in practice to deal with these interdependencies during and after implementation. We emphasize the work of sorting out and dealing with various types...... interactions, mechanisms, and couplings are emphasized. We base our paper on an empirical case study from a Norwegian hospital, where a seemingly trivial project aimed at the introduction of scanners turned out to be more complex than expected. This we claim is partly due to the interdependencies and tight...

  8. Calculation of elastic constants of BCC transition metals: tight-binding recursion method

    International Nuclear Information System (INIS)

    Masuda, K.; Hamada, N.; Terakura, K.

    1984-01-01

    The elastic constants of BCC transition metals (Fe, Nb, Mo and W) are calculated by using the tight-binding d band and the Born-Mayer repulsive potential. Introducing a small distortion characteristic to C 44 (or C') elastic deformation and calculating the energy change up to second order in the atomic displacement, the shear elastic constants C 44 and C' are determined. The elastic constants C 11 and C 12 are then calculated by using the relations B=1/3(C 11 + 2C 12 ) and C'=1/2(C 11 -C 12 ), where B is the bulk modulus. In general, the agreement between the present results and the experimental values is satisfactory. The characteristic elasticity behaviour, i.e. the strong Nsub(d) (number of d electrons) dependence of the observed anisotropy factor A=C 44 /C', will also be discussed. (author)

  9. Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells

    DEFF Research Database (Denmark)

    Del Vecchio, Giovanna; Tscheik, Christian; Tenz, Kareen

    2012-01-01

    opens the paracellular space acting on TJ proteins and actin cytoskeleton. Its action on claudin-5 is not understood so far. Epithelial and endothelial systems were used to evaluate the effect of caprate on claudin-5 in TJ-free cells and on claudin-5 fully integrated in TJ. To this aim, confocal......-actin content in Madin–Darby canine kidney-II cells expressing Flag-claudin-5, thereby increasing the permeability to the small molecule lucifer yellow. Interestingly, zonula occludens protein 1 (ZO-1), which links transmembranous TJ proteins to the actin cytoskeleton, was not affected by caprate treatment...... of endothelial and epithelial cells. In conclusion, the study further elucidates the cellular effects of caprate at the tight junctions....

  10. Mechanical Control of ATP Synthase Function: Activation Energy Difference between Tight and Loose Binding Sites

    KAUST Repository

    Beke-Somfai, Tamás

    2010-01-26

    Despite exhaustive chemical and crystal structure studies, the mechanistic details of how FoF1-ATP synthase can convert mechanical energy to chemical, producing ATP, are still not fully understood. On the basis of quantum mechanical calculations using a recent highresolution X-ray structure, we conclude that formation of the P-O bond may be achieved through a transition state (TS) with a planar PO3 - ion. Surprisingly, there is a more than 40 kJ/mol difference between barrier heights of the loose and tight binding sites of the enzyme. This indicates that even a relatively small change in active site conformation, induced by the γ-subunit rotation, may effectively block the back reaction in βTP and, thus, promote ATP. © 2009 American Chemical Society.

  11. Proceedings of the CERI 2006 oil conference : tight as a drum

    International Nuclear Information System (INIS)

    2006-01-01

    Since 2004, the tight world oil market throughout the entire supply chain has been reflected in high and volatile prices for premium crude, wide crude quality differentials, and high refining margins. This oil conference was attended by international energy experts who addressed these, and other important issues affecting market developments. In addition to issues affecting world oil prices in the short-term as well as long-term world oil demand, the presentations addressed oil supply potential and oil price differentials. Geopolitical hotspots affecting the market were also discussed along with markets for Canadian oil and factors that could impede Alberta's oil sands development, including transportation options for oil sands operators. The conference featured 23 presentations, of which 2 have been catalogued separately for inclusion in this database. refs., tabs., figs

  12. Tight cohesion between glycolipid membranes results from balanced water-headgroup interactions

    Science.gov (United States)

    Kanduč, Matej; Schlaich, Alexander; de Vries, Alex H.; Jouhet, Juliette; Maréchal, Eric; Demé, Bruno; Netz, Roland R.; Schneck, Emanuel

    2017-04-01

    Membrane systems that naturally occur as densely packed membrane stacks contain high amounts of glycolipids whose saccharide headgroups display multiple small electric dipoles in the form of hydroxyl groups. Experimentally, the hydration repulsion between glycolipid membranes is of much shorter range than that between zwitterionic phospholipids whose headgroups are dominated by a single large dipole. Using solvent-explicit molecular dynamics simulations, here we reproduce the experimentally observed, different pressure-versus-distance curves of phospholipid and glycolipid membrane stacks and show that the water uptake into the latter is solely driven by the hydrogen bond balance involved in non-ideal water/sugar mixing. Water structuring effects and lipid configurational perturbations, responsible for the longer-range repulsion between phospholipid membranes, are inoperative for the glycolipids. Our results explain the tight cohesion between glycolipid membranes at their swelling limit, which we here determine by neutron diffraction, and their unique interaction characteristics, which are essential for the biogenesis of photosynthetic membranes.

  13. Genome Engineering of the 2,3-Butanediol Biosynthetic Pathway for Tight Regulation in Cyanobacteria.

    Science.gov (United States)

    Nozzi, Nicole E; Atsumi, Shota

    2015-11-20

    Cyanobacteria have gained popularity among the metabolic engineering community as a tractable photosynthetic host for renewable chemical production. However, though a number of successfully engineered production systems have been reported, long-term genetic stability remains an issue for cyanobacterial systems. The genetic engineering toolbox for cyanobacteria is largely lacking inducible systems for expression control. The characterization of tight regulation systems for use in cyanobacteria may help to alleviate this problem. In this work we explore the function of the IPTG inducible promoter P(L)lacO1 in the model cyanobacterium Synechococcus elongatus PCC 7942 as well as the effect of gene order within an operon on pathway expression. According to our experiments, P(L)lacO1 functions well as an inducible promoter in S. elongatus. Additionally, we found that gene order within an operon can strongly influence control of expression of each gene.

  14. Super-resolution longitudinally polarized light needle achieved by tightly focusing radially polarized beams

    Science.gov (United States)

    Shi, Chang-kun; Nie, Zhong-quan; Tian, Yan-ting; Liu, Chao; Zhao, Yong-chuang; Jia, Bao-hua

    2018-01-01

    Based on the vector diffraction theory, a super-resolution longitudinally polarized optical needle with ultra-long depth of focus ( DOF) is generated by tightly focusing a radially polarized beam that is modulated by a self-designed ternary hybrid (phase/amplitude) filter (THF). Both the phase and the amplitude patterns of THF are judiciously optimized by the versatile particle swarm optimization (PSO) searching algorithm. For the focusing configuration with a combination of a high numerical aperture ( NA) and the optimized sine-shaped THFs, an optical needle with the full width at half maximum ( FWHM) of 0.414λ and the DOF of 7.58λ is accessed, which corresponds to an aspect ratio of 18.3. The demonstrated longitudinally polarized super-resolution light needle with high aspect ratio opens up broad applications in high-density optical data storage, nano-photolithography, super-resolution imaging and high-efficiency particle trapping.

  15. Achieving tight glycemic control with new technology: the role of the advanced practice nurse.

    Science.gov (United States)

    Howell, Soo J

    2012-01-01

    Cardiac surgery remains one of the most commonly performed surgeries in the world. Intensive insulin therapy has shown to reduce infection in patients undergoing open-heart surgery and is considered standard of care. New technologies are available to achieve and maintain recommended blood glucose goals. These include computer-driven intensive insulin protocols (vs paper-based algorithms) and continuous blood glucose monitors. Managing tight glucose control in cardiac surgery patients has been shown to decrease costs in terms of measurable outcomes including infection, mortality, and length of stay. The advanced practice nurse is uniquely qualified to implement new technologies and can be instrumental in increasing compliance with clinical practice guidelines while decreasing hospital costs.

  16. Rate Transient Analysis for Multistage Fractured Horizontal Well in Tight Oil Reservoirs considering Stimulated Reservoir Volume

    Directory of Open Access Journals (Sweden)

    Ruizhong Jiang

    2014-01-01

    Full Text Available A mathematical model of multistage fractured horizontal well (MsFHW considering stimulated reservoir volume (SRV was presented for tight oil reservoirs. Both inner and outer regions were assumed as single porosity media but had different formation parameters. Laplace transformation method, point source function integration method, superposition principle, Stehfest numerical algorithm, and Duhamel’s theorem were used comprehensively to obtain the semianalytical solution. Different flow regimes were divided based on pressure transient analysis (PTA curves. According to rate transient analysis (RTA, the effects of related parameters such as SRV radius, storativity ratio, mobility ratio, fracture number, fracture half-length, and fracture spacing were analyzed. The presented model and obtained results in this paper enrich the performance analysis models of MsFHW considering SRV.

  17. TGF-betas: their role in testicular function and Sertoli cell tight junction dynamics.

    Science.gov (United States)

    Lui, Wing-Yee; Lee, Will M; Cheng, C Yan

    2003-06-01

    Transforming growth factor-betas (TGF-betas) are known to regulate multiple physiological functions in the testis, which include spermatogenesis, Leydig cell steroidogenesis, extracellular matrix synthesis and testis development. More recent studies have shown that TGF-beta3 also regulates Sertoli cell tight junction (TJ) dynamics in vitro via the p38 mitogen-activated protein (MAP) kinase pathway, suggesting that this cytokine plays a crucial role in regulating the opening and closing of the blood-testis barrier (BTB). This in turn regulates the passage of pre-leptotene and leptotene spermatocytes across the BTB at stages VIII-XI of the seminiferous epithelial cycle. This review summarizes recent advances of studies on TGF-betas in the testis, highlighting their regulatory role in TJ dynamics.

  18. Decomposition Patterns of Three C20 Isomer Clusters: Tight-binding Molecular Dynamics Simulation

    International Nuclear Information System (INIS)

    Lee, Changhoon; Lee, Kee Hag

    2016-01-01

    We investigated the decomposition pattern of three C 20 carbon isomer clusters using molecular dynamics simulations combined with the empirical tight-binding total energy calculation method. Here, the thermodynamic behaviors show up for 2 ps. Dynamic behavior is researched by considering the change in assembly energy, bond distance distribution, total energy, and potential energy as a function of temperature. The bonds start breaking around 3300, 4500, and 5100 K for cage, bowl, and ring isomers, respectively. Once a bond is broken, strain accumulates on the neighbors of that atom, and bond cleavage is further accelerated at the neighboring atoms. Based on the snapshots of decomposition, we suggest a C 20 formation scenario from linear carbon clusters to ring, bowl, or cage isomers.

  19. Relaxed and partially relaxed magnetic equilibria in tight-aspect-ratio tori

    International Nuclear Information System (INIS)

    Browning, P.K.; Clegg, J.R.; Duck, R.C.; Rusbridge, M.G.

    1993-01-01

    Force-free equilibrium magnetic fields in tight-aspect-ratio toroidal configurations are investigated. The study is mainly directed to modelling field configurations in the 'rodomak', a modification to the SPHEX gun-injected spheromak in which a current-carrying rod is inserted along the geometric axis. A family of analytical relaxed states (∇ x B = μB, μ constant) is presented for a torus of rectangular cross section, with boundary conditions allowing for flux embedded in the walls, representing the gun. Numerically calculated fields in SPHEX geometry, with μ profiles relevant to the driven phase of operation, are also given. The dependence of the field configurations and global quantities such as energy, helicity and toroidal current on the controlling parameters (gun flux, gun current and rod current) and geometry is discussed. (author)

  20. Double strand break repair: two mechanisms in competition but tightly linked to cell cycle

    International Nuclear Information System (INIS)

    Delacote, F.

    2002-11-01

    DNA double strand breaks (DSB) are highly toxic damage although they can be induced to create genetic diversity. Two distinct pathways can repair DSB: Homologous Recombination (HR) and Non Homologous End Joining (NHEJ). If un- or mis-repaired, this damage can lead to cancer. Thus, it is essential to investigate how these two pathways are regulated for DSB repair. NHEJ inhibition leads to HR DSB repair stimulation. However, this channeling to HR is tightly linked to cell cycle since NHEJ and HR are active in G1/early S and late S/G2, respectively. Our results suggest that G1-unrepaired DSB go through S phase to be repaired by HR in G2. Those results allow a better understanding of DSB repair mechanisms regulation. (author)

  1. Fields of an ultrashort tightly focused radially polarized laser pulse in a linear response plasma

    Science.gov (United States)

    Salamin, Yousef I.

    2017-10-01

    Analytical expressions for the fields of a radially polarized, ultrashort, and tightly focused laser pulse propagating in a linear-response plasma are derived and discussed. The fields are obtained from solving the inhomogeneous wave equations for the vector and scalar potentials, linked by the Lorenz gauge, in a plasma background. First, the scalar potential is eliminated using the gauge condition, then the vector potential is synthesized from Fourier components of an initial uniform distribution of wavenumbers, and the inverse Fourier transformation is carried out term-by-term in a truncated series (finite sum). The zeroth-order term in, for example, the axial electric field component is shown to model a pulse much better than its widely used paraxial approximation counterpart. Some of the propagation characteristics of the fields are discussed and all fields are shown to have manifested the expected limits for propagation in a vacuum.

  2. Cowdung gas

    Energy Technology Data Exchange (ETDEWEB)

    A basic guide for the design and construction of a small biogas plant is presented. The gas holder consists of a battery of seven used oil drums bound together with interconnected via plastic piping. Most other components, with the exception of metal valves and joints, are made of wood, stone or cement.

  3. Gas sensor

    Science.gov (United States)

    Schmid, Andreas K.; Mascaraque, Arantzazu; Santos, Benito; de la Figuera, Juan

    2014-09-09

    A gas sensor is described which incorporates a sensor stack comprising a first film layer of a ferromagnetic material, a spacer layer, and a second film layer of the ferromagnetic material. The first film layer is fabricated so that it exhibits a dependence of its magnetic anisotropy direction on the presence of a gas, That is, the orientation of the easy axis of magnetization will flip from out-of-plane to in-plane when the gas to be detected is present in sufficient concentration. By monitoring the change in resistance of the sensor stack when the orientation of the first layer's magnetization changes, and correlating that change with temperature one can determine both the identity and relative concentration of the detected gas. In one embodiment the stack sensor comprises a top ferromagnetic layer two mono layers thick of cobalt deposited upon a spacer layer of ruthenium, which in turn has a second layer of cobalt disposed on its other side, this second cobalt layer in contact with a programmable heater chip.

  4. Interaction between transcellular and paracellular water transport pathways through Aquaporin 5 and the tight junction complex.

    Science.gov (United States)

    Kawedia, Jitesh D; Nieman, Michelle L; Boivin, Gregory P; Melvin, James E; Kikuchi, Ken-Ichiro; Hand, Arthur R; Lorenz, John N; Menon, Anil G

    2007-02-27

    To investigate potential physiological interactions between the transcellular and paracellular pathways of water transport, we asked whether targeted deletion of Aquaporin 5 (AQP5), the major transcellular water transporter in salivary acinar cells, affected paracellular transport of 4-kDa FITC-labeled dextran (FITC-D), which is transported through the paracellular but not the transcellular route. After i.v. injection of FITC-D into either AQP5 wild-type or AQP5-/- mice and saliva collection for fixed time intervals, we show that the relative amount of FITC-D transported in the saliva of AQP5-/- mice is half that in matched AQP5+/+ mice, indicating a 2-fold decrease in permeability of the paracellular barrier in mice lacking AQP5. We also found a significant difference in the proportion of transcellular vs. paracellular transport between male and female mice. Freeze-fracture electron microscopy revealed an increase in the number of tight junction strands of both AQP5+/+ and AQP5-/- male mice after pilocarpine stimulation but no change in strand number in female mice. Average acinar cell volume was increased by approximately 1.4-fold in glands from AQP5-/- mice, suggesting an alteration in the volume-sensing machinery of the cell. Western blots revealed that expression of Claudin-7, Claudin-3, and Occludin, critical proteins that regulate the permeability of the tight junction barrier, were significantly decreased in AQP5-/- compared with AQP5+/+ salivary glands. These findings reveal the existence of a gender-influenced molecular mechanism involving AQP5 that allows transcellular and paracellular routes of water transport to act in conjunction.

  5. EFFECTIVENESS OF PNF STRETCHING AND CYCLIC STRETCHING OF CALF TIGHTNESS ON COLLEGE GOING GIRLS

    Directory of Open Access Journals (Sweden)

    Ashlesha Sirari

    2015-06-01

    Full Text Available Background: Flexibility helps with injury prevention, the reduction of soreness following a workout, and a general sense of well-being. There are different stretching techniques and protocols for improvements in calf extensibility and flexibility. The purpose of the study was to investigate the effectiveness of two techniques i.e. CYCLIC and PNF stretching which improves calf flexibility. This study was done to find the effectiveness of calf Cyclic and PNF stretching technique to improve calf flexibility. Methods: 30 subjects with age group 21-22 years were randomly allocated to 2 groups equally. Group 1(n=15 were given CYCLIC and group 2(n=15 were given PNF stretching technique. Plantar flexion was used to measure the calf tightness which was done before and after the treatment. Treatment was given for 7 days and on the 7th day the calf tightness was again measured. Results: The mean difference of the CYCLIC is 4.6 and mean difference of PNF is 4.7 which indicate that CYCLIC and PNF both are effective to improve calf flexibility but PNF is more effective than CYCLIC to improve calf flexibility. Conclusion: The neurophysiological basis of PNF, stating that the excitatory efficient of the neuromuscular spindle or the inhibitory afferent of the Golgi tendon organ (GTO or both are responsible for the effects. During PNF stretch and isometric contraction of stretched agonists for extended period may cause activation of its neuromuscular spindle. The increase in tension created during the isometric contraction of the pre – lengthened agonist contracts concentrically. Both the fascia & the spindle of the agonist adjust to the nearly lengthened position. These impulses travel via causing post synaptic inhibition of the motor neuron to agonist increasing the tension from the GTO. These impulses can override the impulses coming from the neuromuscular spindles arousing the muscle to reflexly resist to the change in length, thus helping in lengthening

  6. Clinical benefits of tight glycaemic control: focus on the intensive care unit.

    Science.gov (United States)

    Mesotten, Dieter; Van den Berghe, Greet

    2009-12-01

    While stress hyperglycaemia has traditionally been regarded as an adaptive, beneficial response, it is clear that hyperglycaemia and hypoglycaemia are associated with increased risk of death in critically ill intensive care unit (ICU) patients. Recent studies on blood-glucose control failed to fully clarify whether this association is causal. Early proof-of-concept single-centre randomised controlled studies found that maintaining normoglycaemia by intensive insulin therapy, as compared with tolerating hyperglycaemia as an adaptive response, improved patient outcome. However, recent large multicentre studies VISEP, GLUCONTROL and NICE-SUGAR) could not confirm this survival benefit. Methodological disparity in the execution of the complex intervention of tight glycaemic control may have contributed significantly to the contradicting results. First, different target ranges for blood glucose were used in the control group of the GLUCONTROL and 'Normoglycemia in intensive care evaluation and survival using glucose algorithm' regulation' (NICE-SUGAR) studies. Second, problems to steer blood-glucose levels within target range in the intervention group resulted in a significant overlap of the treatment groups. Third, allowing inaccurate blood-glucose measurement devices, in combination with different blood sampling sites and types of infusion pumps, may have led to unnoticed swings in blood-glucose levels. Fourth, the level of expertise of the intensive care nurses with the therapy may have been variable due to low number of study patients per centre. Finally, the studies on tight blood-glucose control were done with vastly different nutritional and end-of-life strategies. The currently available studies do not allow to confidently recommend one optimal target for glucose in heterogeneous ICU patient groups and settings. Provided that adequate devices for blood-glucose measurement and insulin administration are available, together with an extensive experience of the

  7. Transient pressure analysis of a volume fracturing well in fractured tight oil reservoirs

    Science.gov (United States)

    Lu, Cheng; Wang, Jiahang; Zhang, Cong; Cheng, Minhua; Wang, Xiaodong; Dong, Wenxiu; Zhou, Yingfang

    2017-12-01

    This paper presents a semi-analytical model to simulate transient pressure curves for a vertical well with a reconstructed fracture network in fractured tight oil reservoirs. In the proposed model, the reservoir is a composite system and contains two regions. The inner region is described as a formation with a finite conductivity hydraulic fracture network and the flow in the fracture is assumed to be linear, while the outer region is modeled using the classical Warren–Root model where radial flow is applied. The transient pressure curves of a vertical well in the proposed reservoir model are calculated semi-analytically using the Laplace transform and Stehfest numerical inversion. As shown in the type curves, the flow is divided into several regimes: (a) linear flow in artificial main fractures; (b) coupled boundary flow; (c) early linear flow in a fractured formation; (d) mid radial flow in the semi-fractures of the formation; (e) mid radial flow or pseudo steady flow; (f) mid cross-flow; (g) closed boundary flow. Based on our newly proposed model, the effects of some sensitive parameters, such as elastic storativity ratio, cross-flow coefficient, fracture conductivity and skin factor, on the type curves were also analyzed extensively. The simulated type curves show that for a vertical fractured well in a tight reservoir, the elastic storativity ratios and crossflow coefficients affect the time and the degree of crossflow respectively. The pressure loss increases with an increase in the fracture conductivity. To a certain extent, the effect of the fracture conductivity is more obvious than that of the half length of the fracture on improving the production effect. With an increase in the wellbore storage coefficient, the fluid compressibility is so large that it might cover the early stage fracturing characteristics. Linear or bilinear flow may not be recognized, and the pressure and pressure derivative gradually shift to the right. With an increase in the skin

  8. Sodium caprate transiently opens claudin-5-containing barriers at tight junctions of epithelial and endothelial cells.

    Science.gov (United States)

    Del Vecchio, G; Tscheik, C; Tenz, K; Helms, H C; Winkler, L; Blasig, R; Blasig, I E

    2012-09-04

    Claudin-5 is a tight junction (TJ) protein which limits the diffusion of small hydrophilic molecules. Thus, it represents a potential pharmacological target to improve drug delivery to the tissues protected by claudin-5-dependent barriers. Sodium caprate is known as an absorption enhancer which opens the paracellular space acting on TJ proteins and actin cytoskeleton. Its action on claudin-5 is not understood so far. Epithelial and endothelial systems were used to evaluate the effect of caprate on claudin-5 in TJ-free cells and on claudin-5 fully integrated in TJ. To this aim, confocal microscopy on live and fixed cells and isolated mouse brain capillaries, Western blotting and permeability assays were employed. Caprate reversibly reduced claudin-5 trans-interactions in TJ-free human embryonic kidney-293 cells expressing claudin-5-YFP. It decreased the membranous claudin-5 and the F-actin content in Madin-Darby canine kidney-II cells expressing Flag-claudin-5, thereby increasing the permeability to the small molecule lucifer yellow. Interestingly, zonula occludens protein 1 (ZO-1), which links transmembranous TJ proteins to the actin cytoskeleton, was not affected by caprate treatment. Similarly, endogenous claudin-5 in the membrane of brain endothelia was displaced together with F-actin, whereas ZO-1 remained unaffected. Caprate transiently opens the paracellular space, reducing the intercellular claudin-5/claudin-5 interactions and the polymerized actin at the perijunctional region of endothelial and epithelial cells. In conclusion, the study further elucidates the cellular effects of caprate at the tight junctions.

  9. Development of tight-binding based GW algorithm and its computational implementation for graphene

    Energy Technology Data Exchange (ETDEWEB)

    Majidi, Muhammad Aziz [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); NUSNNI-NanoCore, Department of Physics, National University of Singapore (NUS), Singapore 117576 (Singapore); Singapore Synchrotron Light Source (SSLS), National University of Singapore (NUS), 5 Research Link, Singapore 117603 (Singapore); Naradipa, Muhammad Avicenna, E-mail: muhammad.avicenna11@ui.ac.id; Phan, Wileam Yonatan; Syahroni, Ahmad [Departemen Fisika, FMIPA, Universitas Indonesia, Kampus UI Depok (Indonesia); Rusydi, Andrivo [NUSNNI-NanoCore, Department of Physics, National University of Singapore (NUS), Singapore 117576 (Singapore); Singapore Synchrotron Light Source (SSLS), National University of Singapore (NUS), 5 Research Link, Singapore 117603 (Singapore)

    2016-04-19

    Graphene has been a hot subject of research in the last decade as it holds a promise for various applications. One interesting issue is whether or not graphene should be classified into a strongly or weakly correlated system, as the optical properties may change upon several factors, such as the substrate, voltage bias, adatoms, etc. As the Coulomb repulsive interactions among electrons can generate the correlation effects that may modify the single-particle spectra (density of states) and the two-particle spectra (optical conductivity) of graphene, we aim to explore such interactions in this study. The understanding of such correlation effects is important because eventually they play an important role in inducing the effective attractive interactions between electrons and holes that bind them into excitons. We do this study theoretically by developing a GW method implemented on the basis of the tight-binding (TB) model Hamiltonian. Unlike the well-known GW method developed within density functional theory (DFT) framework, our TB-based GW implementation may serve as an alternative technique suitable for systems which Hamiltonian is to be constructed through a tight-binding based or similar models. This study includes theoretical formulation of the Green’s function G, the renormalized interaction function W from random phase approximation (RPA), and the corresponding self energy derived from Feynman diagrams, as well as the development of the algorithm to compute those quantities. As an evaluation of the method, we perform calculations of the density of states and the optical conductivity of graphene, and analyze the results.

  10. A triple origin for the lack of tight coplanar circumbinary planets around short-period binaries

    Science.gov (United States)

    Hamers, Adrian; Perets, Hagai B.; Portegies Zwart, Simon

    2015-12-01

    Detection of transiting circumbinary planets is more tractable around short-period binaries. However, sofar, no such binaries have been found with orbits shorter than 7 days. Short-period main sequence binaries have been suggested to form in triple systems, through a combination of secular Kozai-Lidov cycles and tidal friction (KLCTF). Here, we show that coplanar circumbinary transiting planets are unlikely to exist around short-period binaries, due to triple evolution. We use secular analysis, N-body simulations and analytic considerations as well as population synthesis models to characterize their overall properties. We find that the existence of a circumbinary planet in a triple is likely to produce one of the following outcomes. (1) Sufficiently massive planets in tight and/or coplanar orbits around the inner binary can partially or completely quench the KL evolution, `shielding' the inner binary from the secular effects of the tertiary, and not allowing the KLCTF process to take place. In this case, the inner binary will not shrink to become a short-period binary. (2) KL evolution is not quenched and it drives the planetary orbit into high eccentricities, giving rise to an unstable configuration, in which the planet is most likely ejected from the system. (3) KL evolution is not quenched, but the planet survives the KLCTF evolution and the formation of the short-period binary; the planet orbit is likely to be much wider than the currently observed inner binary orbit, and is likely to be inclined in respect to the binary orbit, as well as eccentric. These outcomes lead to two main conclusions: (1) it is unlikely to find a (massive) planet on a tight and coplanar orbit around a short-period main-sequence binary, and (2) the frequency, masses and orbits of non-coplanar circumbinary planets in short-period binaries are constrained by their secular evolution.

  11. Enteric Pathogens and Their Toxin-Induced Disruption of the Intestinal Barrier through Alteration of Tight Junctions in Chickens.

    Science.gov (United States)

    Awad, Wageha A; Hess, Claudia; Hess, Michael

    2017-02-10

    Maintaining a healthy gut environment is a prerequisite for sustainable animal production. The gut plays a key role in the digestion and absorption of nutrients and constitutes an initial organ exposed to external factors influencing bird's health. The intestinal epithelial barrier serves as the first line of defense between the host and the luminal environment. It consists of a continuous monolayer of intestinal epithelial cells connected by intercellular junctional complexes which shrink the space between adjacent cells. Consequently, free passing of solutes and water via the paracellular pathway is prevented. Tight junctions (TJs) are multi-protein complexes which are crucial for the integrity and function of the epithelial barrier as they not only link cells but also form channels allowing permeation between cells, resulting in epithelial surfaces of different tightness. Tight junction's molecular composition, ultrastructure, and function are regulated differently with regard to physiological and pathological stimuli. Both in vivo and in vitro studies suggest that reduced tight junction integrity greatly results in a condition commonly known as "leaky gut". A loss of barrier integrity allows the translocation of luminal antigens (microbes, toxins) via the mucosa to access the whole body which are normally excluded and subsequently destroys the gut mucosal homeostasis, coinciding with an increased susceptibility to systemic infection, chronic inflammation and malabsorption. There is considerable evidence that the intestinal barrier dysfunction is an important factor contributing to the pathogenicity of some enteric bacteria. It has been shown that some enteric pathogens can induce permeability defects in gut epithelia by altering tight junction proteins, mediated by their toxins. Resolving the strategies that microorganisms use to hijack the functions of tight junctions is important for our understanding of microbial pathogenesis, because some pathogens can

  12. Regulation of tight junctions by sex hormones in normal human endometrial epithelial cells and uterus cancer cell line Sawano.

    Science.gov (United States)

    Someya, Masayuki; Kojima, Takashi; Ogawa, Marie; Ninomiya, Takafumi; Nomura, Kazuaki; Takasawa, Akira; Murata, Masaki; Tanaka, Satoshi; Saito, Tsuyoshi; Sawada, Norimasa

    2013-11-01

    The number of patients with uterine endometrial carcinoma, the cause of which involves sex hormones, has recently been growing rapidly because of increases in life expectancy and obesity. Tight junction proteins claudin-3 and -4 are receptors of Clostridium perfringens enterotoxin (CPE) and increase during endometrial carcinogenesis. In the present study of normal human endometrial epithelial (HEE) cells and the uterus cancer cell line Sawano, we investigate changes in the expression of tight junction proteins including claudin-3 and -4, the fence and barrier functions of the tight junction and the cytotoxic effects of CPE by sex hormones. In primary cultured HEE cells, treatment with progesterone (P4) but not estradiol (E2), induced claudin-1, -3, -4 and -7 and occludin, together with the downregulation of the barrier function but not the fence function. In Sawano cells, claudin-3 and -4 were upregulated by E2 but not by P4, together with a disruption of both the barrier and fence function. In primary cultured HEE cells, claudin-3 and -4 were localized at the apicalmost regions (tight junction areas) and no cytotoxicity of CPE was observed. In Sawano cells, claudin-3 and -4 were found not only in the apicalmost regions but also at the basolateral membrane and the cytotoxicity of CPE was enhanced by E2. Thus, tight junctions are physiological regulated by sex hormones in normal HEE cells during the menstrual cycle suggesting that safer and more effective therapeutic methods targeting claudins in uterine cancer can be developed.

  13. Strain-dependent augmentation of tight-junction barrier function in human primary epidermal keratinocytes by Lactobacillus and Bifidobacterium lysates.

    Science.gov (United States)

    Sultana, Reshma; McBain, Andrew J; O'Neill, Catherine A

    2013-08-01

    In this study, we investigated whether probiotic lysates can modify the tight-junction function of human primary keratinocytes. The keratinocytes were grown on cell culture inserts and treated with lysates from Bifidobacterium longum, Lactobacillus plantarum, Lactobacillus reuteri, Lactobacillus fermentum, or Lactobacillus rhamnosus GG. With the exception of L. fermentum (which decreased cell viability), all strains markedly enhanced tight-junction barrier function within 24 h, as assessed by measurements of transepithelial electrical resistance (TEER). However, B. longum and L. rhamnosus GG were the most efficacious, producing dose-dependent increases in resistance that were maintained for 4 days. These increases in TEER correlated with elevated expression of tight-junction protein components. Neutralization of Toll-like receptor 2 abolished both the increase in TEER and expression of tight-junction proteins induced by B. longum, but not L. rhamnosus GG. These data suggest that some bacterial strains increase tight-junction function via modulation of protein components but the different pathways involved may vary depending on the bacterial strain.

  14. Potential evaluation on CO2-EGR in tight and low-permeability reservoirs

    Directory of Open Access Journals (Sweden)

    Yunqing Shi

    2017-07-01

    Full Text Available CO2-EGR, i.e. enhanced gas recovery by injecting CO2, is to displace natural gas by injecting CO2 in the supercritical phase. It can both enhance the recovery of gas reservoirs and realize CO2 storage. Currently, this technique is still at its exploring stage. The effect of CO2-EGR is not clarified, the geologic conditions for CO2-EGR are not definite, and the rational working system for CO2-EGR is not available. In this paper, the long-core experiment was conducted to determine whether and how much the recovery of low-permeability reservoirs can be enhanced by injecting CO2. According to the experimental results, the recovery can be enhanced by 12% when CO2 content in produced gas is more than 10%. Moreover, the multi-component seepage mathematical model was built for displacing natural gas by injecting supercritical CO2, and the model accuracy was verified using laboratory data. With this mathematical model, the influence factors for displacing natural gas by injecting supercritical CO2 were analyzed in order to define the conditions for selecting favorable zones. The Well DK13 area in the Daniudi gas field, Ordos Basin, was selected for potential evaluation of CO2-EGR. As indicated by the numerical simulation results, when CO2 content of producing wells in the Well DK13 area is 10% (with a lower cost for corrosion prevention, the ratio of CO2-EGR is 8.0–9.5%, and 31.1% HCPV(hydrocarbon pores volume of CO2 storage can be realized. It is thus concluded that the CO2-EGR technique can enhance the recovery of gas reservoirs and also store CO2 underground, contributing to the increase of both social and economic benefits.

  15. Numerical Investigation of the Transient Behavior of a Hot Gas Duct under Rapid Depressurization

    Directory of Open Access Journals (Sweden)

    JingBao Liu

    2016-01-01

    Full Text Available A hot gas duct is an indispensable component for the nuclear-process heat applications of the Very-High-Temperature Reactor (VHTR, which has to fulfill three requirements: to withstand high temperature, high pressure, and large pressure transient. In this paper, numerical investigation of pressure transient is performed for a hot gas duct under rapid depressurization. System depressurization imposes an imploding pressure differential on the internal structural elements of a hot gas duct, the structural integrity of which is susceptible to being damaged. Pressure differential and its imposed duration, which are two key factors to evaluate the damage severity of a hot gas duct under depressurization, are examined in regard to depressurization rate and insulation packing tightness. It is revealed that depressurization rate is a decisive parameter for controlling the pressure differential and its duration, whereas insulating-packing tightness has little effect on them.

  16. β-Conglycinin Reduces the Tight Junction Occludin and ZO-1 Expression in IPEC-J2

    Directory of Open Access Journals (Sweden)

    Yuan Zhao

    2014-01-01

    Full Text Available Soybean allergy presents a health threat to humans and animals. The mechanism by which food/feed allergen β-conglycinin injures the intestinal barrier has not been well understood. In this study, the changes of epithelial permeability, integrity, metabolic activity, the tight junction (TJ distribution and expression induced by β-conglycinin were evaluated using IPEC-J2 model. The results showed a significant decrease of trans-epithelial electrical resistance (TEER (p < 0.001 and metabolic activity (p < 0.001 and a remarkable increase of alkaline phosphatase (AP activity (p < 0.001 in a dose-dependent manner. The expression levels of tight junction occludin and ZO-1 were decreased (p < 0.05. The reduced fluorescence of targets and change of cellular morphology were recorded. The tight junction occludin and ZO-1 mRNA expression linearly declined with increasing β-conglycinin (p < 0.001.

  17. Managing tight-binding receptors for new separations technologies. Annual progress report, September 15, 1996 - June 10, 1997

    International Nuclear Information System (INIS)

    Busch, D.H.; Givens, R.S.

    1997-01-01

    'This program is fully staffed and all proposed investigations are proceeding as outlined in the Task Schedule of the original proposal. The program aims remain unchanged and excellent progress is reported below. The authors anticipate no substantial unexpended funds from the first year''s budget at the end of the first year of support. Any such remaining funds will certainly be less than 10% of the budget; less than 5% is expected. Three projects make up this program and each focuses on a single aspect of the major problem of overcoming the inherent slow reaction rates of tight-binding ligands. In a logical order, Project 1 addresses the rates of formation of metal complexes using tight-binding ligands; Project 2 addresses the rate of release of metal ions from complexes with tight-binding ligands; and Project 3 provides the possibility of a new technology that should be unimpeded by the inherent dilatory rates.'

  18. Managing tight-binding receptors for new separations technologies. Annual progress report, September 15, 1996--June 10, 1997

    Energy Technology Data Exchange (ETDEWEB)

    Busch, D.H.; Givens, R.S.

    1997-01-01

    'This program is fully staffed and all proposed investigations are proceeding as outlined in the Task Schedule of the original proposal. The program aims remain unchanged and excellent progress is reported below. The authors anticipate no substantial unexpended funds from the first year''s budget at the end of the first year of support. Any such remaining funds will certainly be less than 10% of the budget; less than 5% is expected. Three projects make up this program and each focuses on a single aspect of the major problem of overcoming the inherent slow reaction rates of tight-binding ligands. In a logical order, Project 1 addresses the rates of formation of metal complexes using tight-binding ligands; Project 2 addresses the rate of release of metal ions from complexes with tight-binding ligands; and Project 3 provides the possibility of a new technology that should be unimpeded by the inherent dilatory rates.'

  19. Absorption enhancement by matching the cross-section of plasmonic nanowires to the field structure of tightly focused beams.

    Science.gov (United States)

    Normatov, Alexander; Spektor, Boris; Leviatan, Yehuda; Shamir, Joseph

    2011-04-25

    Nanostructured materials, designed for enhanced light absorption, are receiving increased scientific and technological interest. In this paper we propose a physical criterion for designing the cross-sectional shape of plasmonic nanowires for improved absorption of a given tightly focused illumination. The idea is to design a shape which increases the matching between the nanowire plasmon resonance field and the incident field. As examples, we design nanowire shapes for two illumination cases: a tightly focused plane wave and a tightly focused beam containing a line singularity. We show that properly shaped and positioned silver nanowires that occupy a relatively small portion of the beam-waist area can absorb up to 65% of the total power of the incident beam.

  20. Documentation of the Oil and Gas Supply Module (OGSM)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    1998-01-01

    The purpose of this report is to define the objectives of the Oil and Gas Supply Model (OGSM), to describe the model`s basic approach, and to provide detail on how the model works. This report is intended as a reference document for model analysts, users, and the public. Projected production estimates of US crude oil and natural gas are based on supply functions generated endogenously within National Energy Modeling System (NEMS) by the OGSM. OGSM encompasses domestic crude oil and natural gas supply by both conventional and nonconventional recovery techniques. Nonconventional recovery includes enhanced oil recovery (EOR), and unconventional gas recovery (UGR) from tight gas formations, Devonian/Antrim shale and coalbeds. Crude oil and natural gas projections are further disaggregated by geographic region. OGSM projects US domestic oil and gas supply for six Lower 48 onshore regions, three offshore regions, and Alaska. The general methodology relies on forecasted profitability to determine exploratory and developmental drilling levels for each region and fuel type. These projected drilling levels translate into reserve additions, as well as a modification of the production capacity for each region. OGSM also represents foreign trade in natural gas, imports and exports by entry region. Foreign gas trade may occur via either pipeline (Canada or Mexico), or via transport ships as liquefied natural gas (LNG). These import supply functions are critical elements of any market modeling effort.

  1. Volcanic gas

    Science.gov (United States)

    McGee, Kenneth A.; Gerlach, Terrance M.

    1995-01-01

    In Roman mythology, Vulcan, the god of fire, was said to have made tools and weapons for the other gods in his workshop at Olympus. Throughout history, volcanoes have frequently been identified with Vulcan and other mythological figures. Scientists now know that the “smoke" from volcanoes, once attributed by poets to be from Vulcan’s forge, is actually volcanic gas naturally released from both active and many inactive volcanoes. The molten rock, or magma, that lies beneath volcanoes and fuels eruptions, contains abundant gases that are released to the surface before, during, and after eruptions. These gases range from relatively benign low-temperature steam to thick hot clouds of choking sulfurous fume jetting from the earth. Water vapor is typically the most abundant volcanic gas, followed by carbon dioxide and sulfur dioxide. Other volcanic gases are hydrogen sulfide, hydrochloric acid, hydrogen, carbon monoxide, hydrofluoric acid, and other trace gases and volatile metals. The concentrations of these gas species can vary considerably from one volcano to the next.

  2. Gas laser tube and method of fabricating same

    International Nuclear Information System (INIS)

    Garman, L.E.

    1975-01-01

    An improved gas laser tube is fabricated by counter boring the ends of a tubular aluminum extrusion having an inner tubular portion supported from an outer tubular portion via the intermediary of a plurality of radially directed support vanes or legs. Metallic transverse walls are sealed across the ends of the tubular extrusion to define the ends of a gas tight metallic envelope. An electrically insulative glow discharge tube is axially disposed within and supported by the inner tubular portion of the extrusion in axial alignment with an optical resonator of the laser tube. (U.S.)

  3. Evaluation Of Gas Diffusion Through Plastic Materials Used In Experimental And Sampling Equipment

    DEFF Research Database (Denmark)

    Kjeldsen, Peter

    1993-01-01

    Plastic materials are often used in experimental and sampling equipment. Plastics are not gas tight, since gases are able to diffuse through the walls of tubing and containers made of plastic. Methods for calculating the significance of gas diffusion through the walls of containers and the walls ...... that the use of silicone rubber in experimental and sampling equipment to be used for anoxic water is, for most cases, prohibited by oxygen diffusion....

  4. Tight Bra in a 34-Year-Old Woman: An Unusual Cause of Mondor’s Disease

    Science.gov (United States)

    2014-01-01

    Mondor’s disease is characterized by thrombophlebitis of the superficial veins of the breast and the chest wall. The list of causes is long. Various types of clothing, mainly tight bras and girdles, have been postulated as causes. We report a case of a 34-year-old woman who referred typical symptoms and signs of Mondor’s disease, without other possible risk factors, and showed the cutaneous findings of the tight bra. Therefore, after distinguishing benign causes of Mondor’s disease from hidden malignant causes, the clinicians should consider this clinical entity. PMID:24995060

  5. From structure to spectra. Tight-binding theory of InGaAs quantum dots

    Energy Technology Data Exchange (ETDEWEB)

    Goldmann, Elias

    2014-07-23

    Self-assembled semiconductor quantum dots have raised considerable interest in the last decades due to a multitude of possible applications ranging from carrier storage to light emitters, lasers and future quantum communication devices. Quantum dots offer unique electronic and photonic properties due to the three-dimensional confinement of charge carriers and the coupling to a quasi-continuum of wetting layer and barrier states. In this work we investigate the electronic structure of In{sub x}Ga{sub 1-x}As quantum dots embedded in GaAs, considering realistic quantum dot geometries and Indium concentrations. We utilize a next-neighbour sp{sup 3}s{sup *} tight-binding model for the calculation of electronic single-particle energies and wave functions bound in the nanostructure and account for strain arising from lattice mismatch of the constituent materials atomistically. With the calculated single-particle wave functions we derive Coulomb matrix elements and include them into a configuration interaction treatment, yielding many-particle states and energies of the interacting many-carrier system. Also from the tight-binding single-particle wave functions we derive dipole transition strengths to obtain optical quantum dot emission and absorption spectra with Fermi's golden rule. Excitonic fine-structure splittings are obtained, which play an important role for future quantum cryptography and quantum communication devices for entanglement swapping or quantum repeating. For light emission suited for long-range quantum-crypted fiber communication InAs quantum dots are embedded in an In{sub x}Ga{sub 1-x}As strain-reducing layer, shifting the emission wavelength into telecom low-absorption windows. We investigate the influence of the strain-reducing layer Indium concentration on the excitonic finestructure splitting. The fine-structure splitting is found to saturate and, in some cases, even reduce with strain-reducing layer Indium concentration, a result being

  6. From structure to spectra. Tight-binding theory of InGaAs quantum dots

    International Nuclear Information System (INIS)

    Goldmann, Elias

    2014-01-01

    Self-assembled semiconductor quantum dots have raised considerable interest in the last decades due to a multitude of possible applications ranging from carrier storage to light emitters, lasers and future quantum communication devices. Quantum dots offer unique electronic and photonic properties due to the three-dimensional confinement of charge carriers and the coupling to a quasi-continuum of wetting layer and barrier states. In this work we investigate the electronic structure of In x Ga 1-x As quantum dots embedded in GaAs, considering realistic quantum dot geometries and Indium concentrations. We utilize a next-neighbour sp 3 s * tight-binding model for the calculation of electronic single-particle energies and wave functions bound in the nanostructure and account for strain arising from lattice mismatch of the constituent materials atomistically. With the calculated single-particle wave functions we derive Coulomb matrix elements and include them into a configuration interaction treatment, yielding many-particle states and energies of the interacting many-carrier system. Also from the tight-binding single-particle wave functions we derive dipole transition strengths to obtain optical quantum dot emission and absorption spectra with Fermi's golden rule. Excitonic fine-structure splittings are obtained, which play an important role for future quantum cryptography and quantum communication devices for entanglement swapping or quantum repeating. For light emission suited for long-range quantum-crypted fiber communication InAs quantum dots are embedded in an In x Ga 1-x As strain-reducing layer, shifting the emission wavelength into telecom low-absorption windows. We investigate the influence of the strain-reducing layer Indium concentration on the excitonic finestructure splitting. The fine-structure splitting is found to saturate and, in some cases, even reduce with strain-reducing layer Indium concentration, a result being counterintuitively. Our result

  7. Tightly-Coupled Plant-Soil Nitrogen Cycling: Comparison of Organic Farms across an Agricultural Landscape.

    Directory of Open Access Journals (Sweden)

    Timothy M Bowles

    Full Text Available How farming systems supply sufficient nitrogen (N for high yields but with reduced N losses is a central challenge for reducing the tradeoffs often associated with N cycling in agriculture. Variability in soil organic matter and management of organic farms across an agricultural landscape may yield insights for improving N cycling and for evaluating novel indicators of N availability. We assessed yields, plant-soil N cycling, and root expression of N metabolism genes across a representative set of organic fields growing Roma-type tomatoes (Solanum lycopersicum L. in an intensively-managed agricultural landscape in California, USA. The fields spanned a three-fold range of soil carbon (C and N but had similar soil types, texture, and pH. Organic tomato yields ranged from 22.9 to 120.1 Mg ha-1 with a mean similar to the county average (86.1 Mg ha-1, which included mostly conventionally-grown tomatoes. Substantial variability in soil inorganic N concentrations, tomato N, and root gene expression indicated a range of possible tradeoffs between yields and potential for N losses across the fields. Fields showing evidence of tightly-coupled plant-soil N cycling, a desirable scenario in which high crop yields are supported by adequate N availability but low potential for N loss, had the highest total and labile soil C and N and received organic matter inputs with a range of N availability. In these fields, elevated expression of a key gene involved in root N assimilation, cytosolic glutamine synthetase GS1, confirmed that plant N assimilation was high even when inorganic N pools were low. Thus tightly-coupled N cycling occurred on several working organic farms. Novel combinations of N cycling indicators (i.e. inorganic N along with soil microbial activity and root gene expression for N assimilation would support adaptive management for improved N cycling on organic as well as conventional farms, especially when plant-soil N cycling is rapid.

  8. Anaesthesia Gas Supply: Gas Cylinders

    OpenAIRE

    Srivastava, Uma

    2013-01-01

    Invention of oxygen cylinder was one of the most important developments in the field of medical practice. Oxygen and other gases were compressed and stored at high pressure in seamless containers constructed from hand-forged steel in1880. Materials technology has continued to evolve and now medical gas cylinders are generally made of steel alloys or aluminum. The filling pressure as well as capacity has increased considerably while at the same time the weight of cylinders has reduced. Today o...

  9. Natural gas marketing II

    International Nuclear Information System (INIS)

    Anon.

    1988-01-01

    This book covers all aspects of gas marketing, from the basic regulatory structure to the latest developments in negotiating agreements and locating markets. Topics include: Federal regulation of the gas industry; Fundamentals of gas marketing contracts; FERC actions encouraging competitive markets; Marketing conditions from the pipelines' perspective; State non-utility regulation of natural gas production, transportation, and marketing; Natural gas wellhead agreements and tariffs; Natural gas processing agreements; Effective management of producer's natural gas contracts; Producer-pipeline litigation; Natural gas purchasing from the perspective of industrial gas users; Gas marketing by co-owners: problems of disproportionate sales, gas balancing, and accounting to royalty owners; Alternatives and new directions in marketing

  10. Grammatical number processing and anticipatory eye movements are not tightly coordinated in English spoken language comprehension

    Directory of Open Access Journals (Sweden)

    Brian eRiordan

    2015-05-01

    Full Text Available Recent studies of eye movements in world-situated language comprehension have demonstrated that rapid processing of morphosyntactic information – e.g., grammatical gender and number marking – can produce anticipatory eye movements to referents in the visual scene. We investigated how type of morphosyntactic information and the goals of language users in comprehension affected eye movements, focusing on the processing of grammatical number morphology in English-speaking adults. Participants’ eye movements were recorded as they listened to simple English declarative (There are the lions. and interrogative (Where are the lions? sentences. In Experiment 1, no differences were observed in speed to fixate target referents when grammatical number information was informative relative to when it was not. The same result was obtained in a speeded task (Experiment 2 and in a task using mixed sentence types (Experiment 3. We conclude that grammatical number processing in English and eye movements to potential referents are not tightly coordinated. These results suggest limits on the role of predictive eye movements in concurrent linguistic and scene processing. We discuss how these results can inform and constrain predictive approaches to language processing.

  11. Learning to exploit a hidden predictor in skill acquisition: Tight linkage to conscious awareness.

    Directory of Open Access Journals (Sweden)

    Randy Tran

    Full Text Available It is often assumed that implicit learning of skills based on predictive relationships proceeds independently of awareness. To test this idea, four groups of subjects played a game in which a fast-moving "demon" made a brief appearance at the bottom of the computer screen, then disappeared behind a V-shaped occluder, and finally re-appeared briefly on either the upper-left or upper-right quadrant of the screen. Points were scored by clicking on the demon during the final reappearance phase. Demons differed in several visible characteristics including color, horn height and eye size. For some subjects, horn height perfectly predicted which side the demon would reappear on. For subjects not told the rule, the subset who demonstrated at the end of the experiment that they had spontaneously discovered the rule showed strong evidence of exploiting it by anticipating the demon's arrival and laying in wait for it. Those who could not verbalize the rule performed no better than a control group for whom the demons moved unpredictably. The implications of this tight linkage between conscious awareness and implicit skill learning are discussed.

  12. Tight junctions: a barrier to the initiation and progression of breast cancer?

    LENUS (Irish Health Repository)

    Brennan, Kieran

    2010-01-01

    Breast cancer is a complex and heterogeneous disease that arises from epithelial cells lining the breast ducts and lobules. Correct adhesion between adjacent epithelial cells is important in determining the normal structure and function of epithelial tissues, and there is accumulating evidence that dysregulated cell-cell adhesion is associated with many cancers. This review will focus on one cell-cell adhesion complex, the tight junction (TJ), and summarize recent evidence that TJs may participate in breast cancer development or progression. We will first outline the protein composition of TJs and discuss the functions of the TJ complex. Secondly we will examine how alterations in these functions might facilitate breast cancer initiation or progression; by focussing on the regulatory influence of TJs on cell polarity, cell fate and cell migration. Finally we will outline how pharmacological targeting of TJ proteins may be useful in limiting breast cancer progression. Overall we hope to illustrate that the relationship between TJ alterations and breast cancer is a complex one; but that this area offers promise in uncovering fundamental mechanisms linked to breast cancer progression.

  13. Band gap engineering in finite elongated graphene nanoribbon heterojunctions: Tight-binding model

    Directory of Open Access Journals (Sweden)

    Benjamin O. Tayo

    2015-08-01

    Full Text Available A simple model based on the divide and conquer rule and tight-binding (TB approximation is employed for studying the role of finite size effect on the electronic properties of elongated graphene nanoribbon (GNR heterojunctions. In our model, the GNR heterojunction is divided into three parts: a left (L part, middle (M part, and right (R part. The left part is a GNR of width WL, the middle part is a GNR of width WM, and the right part is a GNR of width WR. We assume that the left and right parts of the GNR heterojunction interact with the middle part only. Under this approximation, the Hamiltonian of the system can be expressed as a block tridiagonal matrix. The matrix elements of the tridiagonal matrix are computed using real space nearest neighbor orthogonal TB approximation. The electronic structure of the GNR heterojunction is analyzed by computing the density of states. We demonstrate that for heterojunctions for which WL = WR, the band gap of the system can be tuned continuously by varying the length of the middle part, thus providing a new approach to band gap engineering in GNRs. Our TB results were compared with calculations employing divide and conquer rule in combination with density functional theory (DFT and were found to agree nicely.

  14. In Vitro Evaluation of Damage by Heavy Metals in Tight and Gap Junctions of Sertoli Cells.

    Science.gov (United States)

    Ramos-Treviño, Juan; Bassol-Mayagoitia, Susana; Ruiz-Flores, Pablo; Espino-Silva, Perla Karina; Saucedo-Cárdenas, Odila; Villa-Cedillo, Sheila Adela; Nava-Hernández, Martha P

    2017-10-01

    The Sertoli cell plays a vital role during the spermatogenesis process and has been identified as one of the main targets of the toxic action of heavy metals on the seminiferous epithelium. In the present work, the effect of lead (Pb), Arsenic (As), and Cadmium (Cd) in primary cultures of Sertoli cells was analyzed by measuring the expression of the genes Cldn11, Ocln, and Gja1 that participate in the tight and gap junctions, which are responsible for maintaining the blood-testis barrier. Sertoli cells were isolated from the testes of Wistar rats. Sertoli cell cultures were exposed separately and at the same concentrations of three heavy metals for 48 h. Subsequently, gene expression was measured by real-time polymerase chain reaction. In the morphological analysis of the cultures, after 24 h, the cultures exposed to Cd showed greatest detachment of the monolayer, followed by those exposed to As and Pb. As for gene expression patterns, As induced a decrease in the expression of the Cldn11 gene at 24 and 48 h (p metals generated different expression patterns in the three genes, we can postulate that the mechanisms of damage that they induce are different; therefore, the effect that they exert on the Sertoli cell occurs through different pathways, generating changes in structural proteins, altering Sertoli cell morphology, and compromising its function in the regulation of the spermatogenesis process.

  15. Grain boundaries in bcc-Fe: a density-functional theory and tight-binding study

    Science.gov (United States)

    Wang, Jingliang; Madsen, Georg K. H.; Drautz, Ralf

    2018-02-01

    Grain boundaries (GBs) have a significant influence on material properties. In the present paper, we calculate the energies of eleven low-Σ ({{Σ }}≤slant 13) symmetrical tilt GBs and two twist GBs in ferromagnetic bcc iron using first-principles density functional theory (DFT) calculations. The results demonstrate the importance of a sufficient sampling of initial rigid body translations in all three directions. We show that the relative GB energies can be explained by the miscoordination of atoms at the GB region. While the main features of the studied GB structures were captured by previous empirical interatomic potential calculations, it is shown that the absolute values of GB energies calculated were substantially underestimated. Based on DFT-calculated GB structures and energies, we construct a new d-band orthogonal tight-binding (TB) model for bcc iron. The TB model is validated by its predictive power on all the studied GBs. We apply the TB model to block boundaries in lath martensite and demonstrate that the experimentally observed GB character distribution can be explained from the viewpoint of interface energy.

  16. Reinforced Ultra-Tightly Coupled GPS/INS System for Challenging Environment

    Directory of Open Access Journals (Sweden)

    Xueyun Wang

    2014-01-01

    Full Text Available Among all integration levels currently available for Global Positioning System (GPS and Inertial Navigation System (INS Integrated System, ultra-tightly coupled (UTC GPS/INS system is the best choice for accurate and reliable navigation. Nevertheless the performance of UTC GPS/INS system degrades in challenging environments, such as jamming, changing noise of GPS signals, and high dynamic maneuvers. When low-end Inertial Measurement Units (IMUs based on MEMS sensors are employed, the performance degradation will be more severe. To solve this problem, a reinforced UTC GPS/INS system is proposed. Two techniques are adopted to deal with jamming and high dynamics. Firstly, adaptive integration Kalman filter (IKF based on fuzzy logics is developed to reinforce the antijamming ability. The parameters of membership functions (MFs are adjusted and optimized through self-developed neutral network. Secondly, a Doppler frequency error estimator based on Kalman filter is designed to improve the navigation performance under high dynamics. A complete simulation platform is established to evaluate the reinforced system. Results demonstrate that the proposed system architecture significantly improves navigation performance in challenging environments and it is a more advanced solution to accurate and reliable navigation than traditional UTC GPS/INS system.

  17. Critical power experiment with a tight-lattice 37-rod bundle

    International Nuclear Information System (INIS)

    Kureta, Masatoshi; Tamai, Hidesada; Ohnuki, Akira; Sato, Takashi; Liu, Wei; Akimoto, Hajime

    2006-01-01

    Since most of critical power or CHF data have been collected in tube, annulus, or BWR geometries under BWR flow conditions, critical power data for highly tight and triangular lattice bundles under low mass velocity are indispensable for thermal-hydraulic design of Reduced-Moderation Water Reactor. Large-scale thermal-hydraulic experiments which use a basic 37-rod bundle test section (rod diameter: 13.0 mm, gap width between rods: 1.3 mm) were therefore carried out in this study within range of 2-9 MPa in pressure and 150-1,000 kg/(m 2 ·s) in mass velocity. Fundamental characteristics of boiling transition were investigated through effects of flow parameter on critical power and those of rod number. It was confirmed that the fundamental characteristics in 37-rod bundle are similar to those in 7-rod bundle and in case of the BWR geometry. The results of the transverse non-uniform power distribution test and subchannel analysis suggest that the critical power becomes higher when the transverse local quality distribution closes to uniform. (author)

  18. DHT deficiency perturbs the integrity of the rat seminiferous epithelium by disrupting tight and adherens junctions

    Directory of Open Access Journals (Sweden)

    Barbara Wiszniewska

    2011-04-01

    Full Text Available In rats with a DHT deficiency induced by finasteride, morphological changes in the seminiferous epithelium were observed. The structural alterations were manifested by the premature germ cells sloughing into the lumen of seminiferous tubules. The etiology of this disorder could be connected with intercellular junctions disintegration. We showed in the immunohistochemical study the changes in expression of some proteins building tight and adherens junctions. The depression of N-cadherin, β-catenin and occludin immunoexpressions could be the reason for the release of immature germ cells from the seminiferous epithelium. However, the observed increase of the immunohistochemical reaction intensity of vinculin, one of the cadherin/catenin complex regulators, could be insufficient to maintain the proper function of adherens junctions. The hormonal imbalance appears to influence the pattern of expression of junctional proteins in the seminiferous epithelium. It could lead to untimely germ cells sloughing, and ultimately could impair fertility. (Folia Histochemica et Cytobiologica 2011, Vol. 49, No. 1, 62–71

  19. A general intermolecular force field based on tight-binding quantum chemical calculations

    Science.gov (United States)

    Grimme, Stefan; Bannwarth, Christoph; Caldeweyher, Eike; Pisarek, Jana; Hansen, Andreas

    2017-10-01

    A black-box type procedure is presented for the generation of a molecule-specific, intermolecular potential energy function. The method uses quantum chemical (QC) information from our recently published extended tight-binding semi-empirical scheme (GFN-xTB) and can treat non-covalently bound complexes and aggregates with almost arbitrary chemical structure. The necessary QC information consists of the equilibrium structure, Mulliken atomic charges, charge centers of localized molecular orbitals, and also of frontier orbitals and orbital energies. The molecular pair potential includes model density dependent Pauli repulsion, penetration, as well as point charge electrostatics, the newly developed D4 dispersion energy model, Drude oscillators for polarization, and a charge-transfer term. Only one element-specific and about 20 global empirical parameters are needed to cover systems with nuclear charges up to radon (Z = 86). The method is tested for standard small molecule interaction energy benchmark sets where it provides accurate intermolecular energies and equilibrium distances. Examples for structures with a few hundred atoms including charged systems demonstrate the versatility of the approach. The method is implemented in a stand-alone computer code which enables rigid-body, global minimum energy searches for molecular aggregation or alignment.

  20. Obesity-induces Organ and Tissue Specific Tight Junction Restructuring and Barrier Deregulation by Claudin Switching.

    Science.gov (United States)

    Ahmad, Rizwan; Rah, Bilal; Bastola, Dhundy; Dhawan, Punita; Singh, Amar B

    2017-07-11

    Obesity increases susceptibility to multiple organ disorders, however, underlying mechanisms remain unclear. The subclinical inflammation assisted by obesity-induced gut permeability may underlie obesity-associated co-morbidities. Despite eminent clinical significance of the obesity led gut barrier abnormalities, its precise molecular regulation remains unclear. It is also unknown whether barrier deregulations, similar to the gut, characterize other vital organs in obese individuals. The claudin family of proteins is integral to the tight junction (TJ), the apical cell-cell adhesion and a key regulator of the epithelial barrier. Using comprehensive physiological and biochemical analysis of intestinal and renal tissues from high-fat diet fed mice, critical for maintaining metabolic homeostasis, this study demonstrates that profound TJ-restructuring by organ and tissue-specific claudin switching characterize obese organs. Protein expression and cellular distribution were examined. In-silico analysis further highlighted potential association of select claudins, modulated by the obesity, with signaling and metabolic pathways of pathological significance. In vitro studies using Leptin or DCA-treatment suggested causal significance of obesity-induced changes in tissue microenvironment in regulating barrier deregulations in tissue-specific manner. Overall, current findings advances our understanding of the molecular undertakings of obesity associated changes that help predispose to specific diseases and also identifies novel windows of preventive and/or therapeutic interventions.

  1. A tightly-coupled domain-decomposition approach for highly nonlinear stochastic multiphysics systems

    Science.gov (United States)

    Taverniers, Søren; Tartakovsky, Daniel M.

    2017-02-01

    Multiphysics simulations often involve nonlinear components that are driven by internally generated or externally imposed random fluctuations. When used with a domain-decomposition (DD) algorithm, such components have to be coupled in a way that both accurately propagates the noise between the subdomains and lends itself to a stable and cost-effective temporal integration. We develop a conservative DD approach in which tight coupling is obtained by using a Jacobian-free Newton-Krylov (JfNK) method with a generalized minimum residual iterative linear solver. This strategy is tested on a coupled nonlinear diffusion system forced by a truncated Gaussian noise at the boundary. Enforcement of path-wise continuity of the state variable and its flux, as opposed to continuity in the mean, at interfaces between subdomains enables the DD algorithm to correctly propagate boundary fluctuations throughout the computational domain. Reliance on a single Newton iteration (explicit coupling), rather than on the fully converged JfNK (implicit) coupling, may increase the solution error by an order of magnitude. Increase in communication frequency between the DD components reduces the explicit coupling's error, but makes it less efficient than the implicit coupling at comparable error levels for all noise strengths considered. Finally, the DD algorithm with the implicit JfNK coupling resolves temporally-correlated fluctuations of the boundary noise when the correlation time of the latter exceeds some multiple of an appropriately defined characteristic diffusion time.

  2. Low-Cost BD/MEMS Tightly-Coupled Pedestrian Navigation Algorithm

    Directory of Open Access Journals (Sweden)

    Tianyu Lin

    2016-05-01

    Full Text Available Pedestrian Dead Reckoning (PDR by combining the Inertial Measurement Unit (IMU and magnetometer is an independent navigation approach based on multiple sensors. Since the inertial component error is significantly determined by the parameters of navigation equations, the navigation precision may deteriorate with time, which is inappropriate for long-time navigation. Although the BeiDou (BD navigation system can provide high navigation precision in most scenarios, the signal from satellites is easily degraded because of buildings or thick foliage. To solve this problem, a tightly-coupled BD/MEMS (Micro-Electro-Mechanical Systems integration algorithm is proposed in this paper, and a prototype was built for implementing the integrated system. The extensive experiments prove that the BD/MEMS system performs well in different environments, such as an open sky environment and a playground surrounded by trees and thick foliage. The proposed algorithm is able to provide continuous and reliable positioning service for pedestrian outdoors and thereby has wide practical application.

  3. Balanced sparse model for tight frames in compressed sensing magnetic resonance imaging.

    Directory of Open Access Journals (Sweden)

    Yunsong Liu

    Full Text Available Compressed sensing has shown to be promising to accelerate magnetic resonance imaging. In this new technology, magnetic resonance images are usually reconstructed by enforcing its sparsity in sparse image reconstruction models, including both synthesis and analysis models. The synthesis model assumes that an image is a sparse combination of atom signals while the analysis model assumes that an image is sparse after the application of an analysis operator. Balanced model is a new sparse model that bridges analysis and synthesis models by introducing a penalty term on the distance of frame coefficients to the range of the analysis operator. In this paper, we study the performance of the balanced model in tight frame based compressed sensing magnetic resonance imaging and propose a new efficient numerical algorithm to solve the optimization problem. By tuning the balancing parameter, the new model achieves solutions of three models. It is found that the balanced model has a comparable performance with the analysis model. Besides, both of them achieve better results than the synthesis model no matter what value the balancing parameter is. Experiment shows that our proposed numerical algorithm constrained split augmented Lagrangian shrinkage algorithm for balanced model (C-SALSA-B converges faster than previously proposed algorithms accelerated proximal algorithm (APG and alternating directional method of multipliers for balanced model (ADMM-B.

  4. Tele-Health Followup Strategy for Tight Control of Disease Activity in Rheumatoid Arthritis

    DEFF Research Database (Denmark)

    Thurah, Annette De; Stengaard-Pedersen, Kristian; Axelsen, Mette

    2018-01-01

    of life and self-efficacy. The non-inferiority margin was a DAS28 change of 0.6. Mean differences were estimated following per-protocol (PP), intention to treat (ITT) and mulitivariate imputation (IMP) analysis. RESULTS: Overall patients had low disease activity at baseline and end follow-up. Demographics......OBJECTIVE: To test the effect of patient-reported outcome (PRO) based tele-health follow-up for tight control of disease activity in patients with rheumatoid arthritis (RA), and the differences between tele-health follow-up performed by rheumatologists or rheumatology nurses. METHODS: A total...... of 294 patients were randomized (1:1:1) to either PRO-based tele-health follow-up carried out by a nurse (PRO-TN) or a rheumatologist (PRO-TR), or conventional out-patient follow-up by physicians. The primary outcome was change in DAS28 after week 52. Secondary outcomes were: physical function, quality...

  5. A parametric thermohydraulic study an advanced pressurized light water reactor with a tight fuel rod lattice

    International Nuclear Information System (INIS)

    Dalle Donne, M.; Hame, W.

    1982-12-01

    A parametric thermohydraulic study for an Advanced Pressurized Light Water Reactor (APWR) with a tight fuel rod lattice has been performed. The APWR improves the uranium utilisation. The APWR core should be placed in a modern German PWR plant. Within this study about 200 different reactors have been calculated. The tightening of the fuel rod lattice implies a decrease of the net electrical output of the plant, which is greater for the heterogeneous reactor than for the homogeneous reactor. APWR cores mean higher core pressure drops and higher water velocities in the core region. The cores tend to be shorter and the number of fuel rods to be higher than for the PWR. At the higher fuel rod pitch to diameter ratios (p/d) the DNB limitation is more stringent than the limitation on the fuel rod linear rating given by the necessity of reflooding after a reactor accident. The contrary is true for the lower p/d ratios. Subcooled boiling in the highest rated coolant channels occurs for the most of the calculated reactors. (orig.) [de

  6. Development of tight-binding, chemical-reaction-dynamics simulator for combinatorial computational chemistry

    International Nuclear Information System (INIS)

    Kubo, Momoji; Ando, Minako; Sakahara, Satoshi; Jung, Changho; Seki, Kotaro; Kusagaya, Tomonori; Endou, Akira; Takami, Seiichi; Imamura, Akira; Miyamoto, Akira

    2004-01-01

    Recently, we have proposed a new concept called 'combinatorial computational chemistry' to realize a theoretical, high-throughput screening of catalysts and materials. We have already applied our combinatorial, computational-chemistry approach, mainly based on static first-principles calculations, to various catalysts and materials systems and its applicability to the catalysts and materials design was strongly confirmed. In order to realize more effective and efficient combinatorial, computational-chemistry screening, a high-speed, chemical-reaction-dynamics simulator based on quantum-chemical, molecular-dynamics method is essential. However, to the best of our knowledge, there is no chemical-reaction-dynamics simulator, which has an enough high-speed ability to perform a high-throughput screening. In the present study, we have succeeded in the development of a chemical-reaction-dynamics simulator based on our original, tight-binding, quantum-chemical, molecular-dynamics method, which is more than 5000 times faster than the regular first-principles, molecular-dynamics method. Moreover, its applicability and effectiveness to the atomistic clarification of the methanol-synthesis dynamics at reaction temperature were demonstrated

  7. Real-time Kinematic Positioning of INS Tightly Aided Multi-GNSS Ionospheric Constrained PPP.

    Science.gov (United States)

    Gao, Zhouzheng; Shen, Wenbin; Zhang, Hongping; Niu, Xiaoji; Ge, Maorong

    2016-07-29

    Real-time Precise Point Positioning (PPP) technique is being widely applied for providing precise positioning services with the significant improvement on satellite precise products accuracy. With the rapid development of the multi-constellation Global Navigation Satellite Systems (multi-GNSS), currently, about 80 navigation satellites are operational in orbit. Obviously, PPP performance is dramatically improved with all satellites compared to that of GPS-only PPP. However, the performance of PPP could be evidently affected by unexpected and unavoidable severe observing environments, especially in the dynamic applications. Consequently, we apply Inertial Navigation System (INS) to the Ionospheric-Constrained (IC) PPP to overcome such drawbacks. The INS tightly aided multi-GNSS IC-PPP model can make full use of GNSS and INS observations to improve the PPP performance in terms of accuracy, availability, continuity, and convergence speed. Then, a set of airborne data is analyzed to evaluate and validate the improvement of multi-GNSS and INS on the performance of IC-PPP.

  8. Consideration of relativistic effects in band structure calculations based on the empirical tight-binding method

    International Nuclear Information System (INIS)

    Hanke, M.; Hennig, D.; Kaschte, A.; Koeppen, M.

    1988-01-01

    The energy band structure of cadmium telluride and mercury telluride materials is investigated by means of the tight-binding (TB) method considering relativistic effects and the spin-orbit interaction. Taking into account relativistic effects in the method is rather simple though the size of the Hamilton matrix doubles. Such considerations are necessary for the interesting small-interstice semiconductors, and the experimental results are reflected correctly in the band structures. The transformation behaviour of the eigenvectors within the Brillouin zone gets more complicated, but is, nevertheless, theoretically controllable. If, however, the matrix elements of the Green operator are to be calculated, one has to use formula manipulation programmes in particular for non-diagonal elements. For defect calculations by the Koster-Slater theory of scattering it is necessary to know these matrix elements. Knowledge of the transformation behaviour of eigenfunctions saves frequent diagonalization of the Hamilton matrix and thus permits a numerical solution of the problem. Corresponding results for the sp 3 basis are available

  9. Acoustic harmonic generation measurement applications: Detection of tight cracks in powder metallurgy compacts

    International Nuclear Information System (INIS)

    Barnard, D.J.; Foley, J.C.

    2000-01-01

    Standard linear ultrasonic testing techniques have long been employed for locating and characterizing relatively open cracks in a wide variety of materials, from metallic alloys and ceramics to composites. In all these materials, the detection of open cracks easily accomplished because the void between the two crack surfaces provides sufficient acoustic impedance mismatch to reflect the incident energy. Closed or partially closed cracks, however, may often go undetected because contacting interfaces allow transmission of ultrasound. In the green (unsintered) state, powder metallurgy compacts typically contain high residual stresses that have the ability to close cracks formed during the compaction process, a result of oxide films, improper powder lubricant, mold design, etc. After sintering, the reduction of residual stresses may no longer be sufficient to close the crack. Although the crack may be more easily detected, it is obvious most desirable to discover defects prior to sintering. It has been shown that the displacements of an interface may be highly nonlinear if a stress wave of sufficient intensity propagates across it, a result of the stress wave either opening or closing the interface. Current efforts involve the application of nonlinear acoustic techniques, in particular acoustic harmonic generation measurements, for the detection and characterization of tightly closed cracks in powder metallurgy parts. A description of the equipment and the measurement technique will be discussed and initial experimental results on sintered and green compacts will be presented. - This work was performed at the Ames Laboratory, Iowa State University under USDOE Contract No. W-7405-ENG-82

  10. Effect of chum salmon egg lectin on tight junctions in Caco-2 cell monolayers.

    Science.gov (United States)

    Nemoto, Ryo; Yamamoto, Shintaro; Ogawa, Tomohisa; Naude, Ryno; Muramoto, Koji

    2015-05-05

    The effect of a chum salmon egg lectin (CSL3) on tight junction (TJ) of Caco-2 cell monolayers was investigated. The lectin opened TJ as indicated by the decrease of the transepithelial electrical resistance (TER) value and the increase of the permeation of lucifer yellow, which is transported via the TJ-mediated paracellular pathway. The effects of CSL3 were inhibited by the addition of 10 mM L-rhamnose or D-galactose which were specific sugars for CSL3. The lectin increased the intracellular Ca2+ of Caco-2 cell monolayers, that could be inhibited by the addition of L-rhamnose. The fluorescence immunostaining of β-actin in Caco-2 cell monolayers revealed that the cytoskeleton was changed by the CSL3 treatment, suggesting that CSL3 depolymerized β-actin to cause reversible TJ structural and functional disruption. Although Japanese jack bean lectin and wheat germ lectin showed similar effects in the decrease of the TER values and the increase of the intracellular Ca2+, they could not be inhibited by the same concentrations of simple sugars, such as D-glucose and N-acetyl-D-glucosamine.

  11. Effect of Chum Salmon Egg Lectin on Tight Junctions in Caco-2 Cell Monolayers

    Directory of Open Access Journals (Sweden)

    Ryo Nemoto

    2015-05-01

    Full Text Available The effect of a chum salmon egg lectin (CSL3 on tight junction (TJ of Caco-2 cell monolayers was investigated. The lectin opened TJ as indicated by the decrease of the transepithelial electrical resistance (TER value and the increase of the permeation of lucifer yellow, which is transported via the TJ-mediated paracellular pathway. The effects of CSL3 were inhibited by the addition of 10 mM L-rhamnose or D-galactose which were specific sugars for CSL3. The lectin increased the intracellular Ca2+ of Caco-2 cell monolayers, that could be inhibited by the addition of L-rhamnose. The fluorescence immunostaining of β-actin in Caco-2 cell monolayers revealed that the cytoskeleton was changed by the CSL3 treatment, suggesting that CSL3 depolymerized β-actin to cause reversible TJ structural and functional disruption. Although Japanese jack bean lectin and wheat germ lectin showed similar effects in the decrease of the TER values and the increase of the intracellular Ca2+, they could not be inhibited by the same concentrations of simple sugars, such as D-glucose and N-acetyl-D-glucosamine.

  12. Yogurt inhibits intestinal barrier dysfunction in Caco-2 cells by increasing tight junctions.

    Science.gov (United States)

    Putt, Kelley K; Pei, Ruisong; White, Heather M; Bolling, Bradley W

    2017-01-25

    Chronic inflammation disrupts intestinal barrier function and may contribute to the pathology of obesity and other diseases. The goal of this study was to determine the mechanism by which yogurt improves intestinal barrier function. Caco-2 cells were differentiated on Transwell inserts and used as a model of intestinal barrier permeability. Transepithelial electrical resistance (TEER) and flux of 4 kDa fluorescein isothiocyanate-dextran (FD) and lucifer yellow (LY) were used as indicators of monolayer integrity and paracellular permeability. Immunofluorescence microscopy and real time quantitative polymerase chain were used to assess the localization and expression of tight junction proteins known to regulate intestinal permeability. Differentiated cells were treated with a vehicle control (C), inflammatory stimulus (I) (interleukin-1β, tumor necrosis factor-α, interferon-γ, and lipopolysaccharide), or I and 0.03 g mL -1 yogurt (IY). After 48 h, I reduced Caco-2 TEER by 46%, while IY reduced TEER by only 27% (P effect on barrier function was reduced at latter stages of digestion.

  13. Tight Junction Proteins Claudin-1 and Occludin Are Important for Cutaneous Wound Healing.

    Science.gov (United States)

    Volksdorf, Thomas; Heilmann, Janina; Eming, Sabine A; Schawjinski, Kathrin; Zorn-Kruppa, Michaela; Ueck, Christopher; Vidal-Y-Sy, Sabine; Windhorst, Sabine; Jücker, Manfred; Moll, Ingrid; Brandner, Johanna M

    2017-06-01

    Tight junction (TJ) proteins are known to be involved in proliferation and differentiation. These processes are essential for normal skin wound healing. Here, we investigated the TJ proteins claudin-1 and occludin in ex vivo skin wound healing models and tissue samples of acute and chronic human wounds and observed major differences in localization/expression of these proteins, with chronic wounds often showing a loss of the proteins at the wound margins and/or in the regenerating epidermis. Knockdown experiments in primary human keratinocytes showed that decreased claudin-1 expression resulted in significantly impaired scratch wound healing, with delayed migration and reduced proliferation. Activation of AKT pathway was significantly attenuated after claudin-1 knockdown, and protein levels of extracellular signal-related kinase 1/2 were reduced. For occludin, down-regulation had no impact on wound healing in normal scratch assays, but after subjecting the cells to mechanical stress, which is normally present in wounds, wound healing was impaired. For both proteins we show that most of these actions are independent from the formation of barrier-forming TJ structures, thus demonstrating nonbarrier-related functions of TJ proteins in the skin. However, for claudin-1 effects on scratch wound healing were more pronounced when TJs could form. Together, our findings provide evidence for a role of claudin-1 and occludin in epidermal regeneration with potential clinical importance. Copyright © 2017 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

  14. The Tight-interlocked Rhythm Section: Production and Perception of Synchronisation in Jazz Trio Performance.

    Science.gov (United States)

    Hofmann, Alex; Wesolowski, Brian C; Goebl, Werner

    2017-01-01

    This study investigates the production and perception of timing, synchronisation and dynamics in jazz trio performances. In a production experiment, six trio combinations of one saxophonist, two bassists, and three drummers were recorded while they performed three popular jazz songs. Onset timing and dynamics of each performer were extracted and analysed. Results showed that the tempo was significantly influenced by the timing of the drummers and all performers showed higher temporal precision on the backbeats. The drummers demonstrated individual swing-ratios, accentuations of beats and intrapersonal asynchronies between simultaneous hi-hat and ride cymbal onsets, which resulted in a hi-hat played 2-26 ms ahead of the pulse of the music. In a subsequent perception test, participants ([Formula: see text]) rated 12 excerpts of the jazz recordings. They selected their preferred version from a pool of stimuli containing the original version, but also manipulations with artificially increased or reduced asynchronies. Stimuli with reduced asynchronies smaller than 19 ms were preferred by the listeners over the original or the fully quantised timing. This suggests that listeners endorse a 'tight-interlocked' jazz rhythm section, with asynchronies smaller than the perceptual threshold (temporal masking), but with natural timing variabilities that makes it distinguishable from a computer-generated playback.

  15. Tight junctions at the blood brain barrier: physiological architecture and disease-associated dysregulation

    Directory of Open Access Journals (Sweden)

    Luissint Anny-Claude

    2012-11-01

    Full Text Available Abstract The Blood–brain barrier (BBB, present at the level of the endothelium of cerebral blood vessels, selectively restricts the blood-to-brain paracellular diffusion of compounds; it is mandatory for cerebral homeostasis and proper neuronal function. The barrier properties of these specialized endothelial cells notably depend on tight junctions (TJs between adjacent cells: TJs are dynamic structures consisting of a number of transmembrane and membrane-associated cytoplasmic proteins, which are assembled in a multimolecular complex and acting as a platform for intracellular signaling. Although the structural composition of these complexes has been well described in the recent years, our knowledge about their functional regulation still remains fragmentary. Importantly, pericytes, embedded in the vascular basement membrane, and perivascular microglial cells, astrocytes and neurons contribute to the regulation of endothelial TJs and BBB function, altogether constituting the so-called neurovascular unit. The present review summarizes our current understanding of the structure and functional regulation of endothelial TJs at the BBB. Accumulating evidence points to a correlation between BBB dysfunction, alteration of TJ complexes and progression of a variety of CNS diseases, such as stroke, multiple sclerosis and brain tumors, as well as neurodegenerative diseases like Parkinson’s and Alzheimer’s diseases. Understanding how TJ integrity is controlled may thus help improve drug delivery across the BBB and the design of therapeutic strategies for neurological disorders.

  16. Overexpression of caveolin-1 attenuates brain edema by inhibiting tight junction degradation.

    Science.gov (United States)

    Choi, Kang-Ho; Kim, Hyung-Seok; Park, Man-Seok; Lee, Eun-Bin; Lee, Jung-Kil; Kim, Joon-Tae; Kim, Ja-Hae; Lee, Min-Cheol; Lee, Hong-Joon; Cho, Ki-Hyun

    2016-10-18

    Cerebral edema from the disruption of the blood-brain barrier (BBB) after cerebral ischemia is a major cause of morbidity and mortality as well as a common event in patients with stroke. Caveolins (Cavs) are thought to regulate BBB functions. Here, we report for the first time that Cav-1 overexpression (OE) decreased brain edema from BBB disruption following ischemic insult. Edema volumes and Cav-1 expression levels were measured following photothrombosis and middle cerebral artery occlusion (MCAO). Endothelial cells that were transduced with a Cav-1 lentiviral expression vector were transplanted into rats. BBB permeability was quantified with Evans blue extravasation. Edema volume was determined from measures of the extravasation area, brain water content, and average fluorescence intensity after Cy5.5 injections. Tight junction (TJ) protein expression was measured with immunoblotting. Cav-1 expression levels and vasogenic brain edema correlated strongly after ischemic insult. Cav-1 expression and BBB disruption peaked 3 d after the MCAO. In addition, intravenous administration of endothelial cells expressing Cav-1 effectively increased the Cav-1 levels 3 d after the MCAO ischemic insult. Importantly, Cav-1 OE ameliorated the vasogenic edema by inhibiting the degradation of TJ protein expression in the acute phase of ischemic stroke. These results suggested that Cav-1 OE protected the integrity of the BBB mainly by preventing the degradation of TJ proteins in rats. These findings need to be confirmed in a clinical setting in human subjects.

  17. Clinical Effects of Dry Needling Among Asymptomatic Individuals With Hamstring Tightness: A Randomized Controlled Trial.

    Science.gov (United States)

    Geist, Kathleen; Bradley, Claire; Hofman, Alan; Koester, Rob; Roche, Fenella; Shields, Annalise; Frierson, Elizabeth; Rossi, Ainsley; Johanson, Marie

    2017-11-01

    Randomized controlled trial. The aim of this study was to determine the effects of dry needling on hamstring extensibility and functional performance tests among asymptomatic individuals with hamstring muscle tightness. Dry needling has been shown to increase range of motion in the upper quarter and may have similar effects in the lower quarter. 27 subjects with hamstring extensibility deficits were randomly assigned to side of treatment (dominant or nondominant) and group (blunt needling or dry needling). The first session included measurement of hamstring extensibility and performance on 4 unilateral hop tests, instruction in home hamstring stretching exercises and needling distal to the ischial tuberosity and midbellies of the medial and lateral hamstrings. A second session, 3-5 days following the first session, included outcome measures and a second needling intervention, and a third session, 4-6 weeks following the first session, included outcome measures only. A 2 × 3 × 2 ANOVA was used to statistically analyze the data. Hamstring extensibility showed a significant side × time interaction (P < .05). The single hop for distance, timed 6-meter hop, and the crossover hop test had a significant main effect of time (P < .05). The triple hop for distance showed a significant side × time × group interaction (P < .05). It does not appear dry needling results in increased extensibility beyond that of stretching alone in asymptomatic individuals. Our study findings suggest that dry needling may improve certain dimensions of functional performance, although no clear conclusion can be made. Intervention, level 2b.

  18. Interatomic electron transport by semiempirical and ab initio tight-binding approaches

    Science.gov (United States)

    Turek, I.; Kudrnovský, J.; Drchal, V.; Szunyogh, L.; Weinberger, P.

    2002-03-01

    A unified approach to interatomic electron transport within Kubo linear-response theory is sketched that is applicable both in semiempirical (matrix-element-based) and ab initio (wave-function-based) tight-binding (TB) techniques. This approach is based on a systematic neglect of the electron motion inside the atomic (Wigner-Seitz) cells leading thus to velocity operators describing pure intersite hopping. This is achieved by using piecewise constant coordinates, i.e., coordinates that are constant inside the cells. The formalism is presented within the simple semiempirical TB method, the TB linear muffin-tin orbital (LMTO) method, and the screened Korringa-Kohn-Rostoker (KKR) method with emphasis on the formal analogy of the derived formulas. The results provide a justification of current assumptions used in semiempirical TB schemes, an assessment of properties of recent TB-LMTO approaches, and an alternative formulation of electron transport within the screened KKR method. The formalism is illustrated by a calculation of residual resistivity of substitutionally disordered fcc Ag-Pd alloys.

  19. 3D micro-optical elements for generation of tightly focused vortex beams

    Directory of Open Access Journals (Sweden)

    Balčytis Armandas

    2015-01-01

    Full Text Available Orbital angular momentum carrying light beams are usedfor optical trapping and manipulation. This emerging trend provides new challenges involving device miniaturization for improved performance and enhanced functionality at the microscale. Here we discus a new fabrication method based on combining the additive 3D structuring capability laser photopolymerization and the substractive sub-wavelength resolution patterning of focused ion beam lithography to produce micro-optical elements capable of compound functionality. As a case in point of this approach binary spiral zone pattern based high numerical aperture micro-lenses capable of generating topological charge carrying tightly focused vortex beams in a single wavefront transformation step are presented. The devices were modelled using finite-difference time-domain simulations, and the theoretical predictions were verified by optically characterizing the propagation properties of light transmitted through the fabricated structures. The resulting devices had focal lengths close to the predicted values of f = 18 µm and f = 13 µm as well as topological charge ℓ dependent vortex focal spot sizes of ~ 1:3 µm and ~ 2:0 µm for ℓ = 1 and ℓ = 2 respectively.

  20. Tightness of Semidefinite Programming Relaxation to Robust Transmit Beamforming with SINR Constraints

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    Yanjun Wang

    2013-01-01

    Full Text Available This paper considers a multiuser transmit beamforming problem under uncertain channel state information (CSI subject to SINR constraints in a downlink multiuser MISO system. A robust transmit beamforming formulation is proposed. This robust formulation is to minimize the transmission power subject to worst-case signal-to-interference-plus-noise ratio (SINR constraints on the receivers. The challenging problem is that the worst-case SINR constraints correspond to an infinite number of nonconvex quadratic constraints. In this paper, a natural semidifinite programming (SDP relaxation problem is proposed to solve the robust beamforming problem. The main contribution of this paper is to establish the tightness of the SDP relaxation problem under proper assumption, which means that the SDP relaxation problem definitely yields rank-one solutions under the assumption. Then the SDP relaxation problem provides globally optimum solutions of the primal robust transmit beamforming problem under proper assumption and norm-constrained CSI errors. Simulation results show the correctness of the proposed theoretical results and also provide a counterexample whose solutions are not rank one. The existence of counterexample shows that the guess that the solutions of the SDP relaxation problem must be rank one is wrong, except that some assumptions (such as the one proposed in this paper hold.