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Sample records for 14-fr peel-away sheath

  1. Placement of large suprapubic tube using peel-away introducer.

    PubMed

    Chiou, R K; Morton, J J; Engelsgjerd, J S; Mays, S

    1995-04-01

    We describe a new method for placing a large suprapubic tube and report our experience with 56 patients. This method uses a specially designed fascial dilator and peel-away introducer to place an 18F Foley catheter suprapubically. In our experience the method is simple and effective for the exchange of a small suprapubic tube to an 18F Foley catheter, and for primary placement of a large suprapubic tube. It is easily performed at the bedside or during a minor procedure with the patient under local anesthesia. PMID:7869492

  2. Elkmont Vehicle Bridge, Construction PeelAway Great Smoky Mountains National ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    Elkmont Vehicle Bridge, Construction Peel-Away - Great Smoky Mountains National Park Roads & Bridges, Elkmont Vehicle Bridge, Spanning Little River at Elkmont Campground, Gatlinburg, Sevier County, TN

  3. Percutaneous placement of a suprapubic tube with peel away sheath introducer.

    PubMed

    O'Brien, W M

    1991-05-01

    A new technique for percutaneous placement of a suprapubic tube has been developed, which allows controlled entry into the bladder over a guide wire to avoid the potential hazards of blind trocar cystotomy. A Foley style catheter can be placed, which is less likely to become dislodged than other types of percutaneous suprapubic catheters currently available. PMID:2016781

  4. NICMOS PEELS AWAY LAYERS OF DUST TO SHOW INNER REGION OF DUSTY NEBULA

    NASA Technical Reports Server (NTRS)

    2002-01-01

    The revived Near Infrared Camera and Multi-Object Spectrometer (NICMOS) aboard NASA's Hubble Space Telescope has penetrated layers of dust in a star-forming cloud to uncover a dense, craggy edifice of dust and gas . This region is called the Cone Nebula (NGC 2264), so named because, in ground-based images, it has a conical shape. NICMOS enables the Hubble telescope to see in near-infrared wavelengths of light, so that it can penetrate the dust that obscures the nebula's inner regions. But the Cone is so dense that even the near-infared 'eyes' of NICMOS can't penetrate all the way through it. The image shows the upper 0.5 light-years of the nebula. The entire nebula is 7 light-years long. The Cone resides in a turbulent star-forming region, located 2,500 light-years away in the constellation Monoceros. Radiation from hot, young stars [located beyond the top of the image] has slowly eroded the nebula over millions of years. Ultraviolet light heats the edges of the dark cloud, releasing gas into the relatively empty region of surrounding space. NICMOS has peeled away the outer layers of dust to reveal even denser dust. The denser regions give the nebula a more three-dimensional structure than can be seen in the visible-light picture at left, taken by the Advanced Camera for Surveys aboard the Hubble telescope. In peering through the dusty facade to the nebula's inner regions, NICMOS has unmasked several stars [yellow dots at upper right]. Astronomers don't know whether these stars are behind the dusty nebula or embedded in it. The four bright stars lined up on the left are in front of the nebula. The human eye cannot see infrared light, so colors have been assigned to correspond with near-infrared wavelengths. The blue light represents shorter near-infrared wavelengths and the red light corresponds to longer wavelengths. The NICMOS color composite image was made by combining photographs taken in J-band, H-band, and Paschen-alpha filters. The NICMOS images were taken

  5. Gravitoelectromagnetic sheath

    NASA Astrophysics Data System (ADS)

    Goutam, H. P.; Karmakar, P. K.

    2015-06-01

    In this paper we propose a gravito-electro-magnetic sheath (GEMS) model to explore the equilibrium properties of the solar plasma system. It describes the solar interior plasma (SIP) on the bounded scale and the solar wind plasma (SWP) on the unbounded scale from the viewpoint of plasma-based theory. This differs from the previously reported gravito-electrostatic sheath (GES) model employed to precisely define the solar surface boundary (SSB) on the fact that the present investigation incorporates variable temperature, magnetic field and collisional processes on the solar plasma flow dynamics. We show that the included parameters play important roles in the solar plasma dynamics. We demonstrate that the SSB location shifts outward as a result of the magnetic field by 14 % in comparison with that predicted by the GES model. As a consequence of the interaction of the plasma with magnetic field, the width of the sheath broadens by 25 % in comparison with the GES model predicted value. This physically means that the magnetic field decreases the distribution of the tiny (inertialess) electrons relative to the massive (inertial) ions, which in turn increases the confining wall potential value resulting in the increased width. Besides, the sonic point moves inward by 8 % as a result of collisions in the SIP that leads to rapid acceleration. Here, collisional dynamics plays an important role in the conversion process of the electron thermal energy into the bulk plasma flow energy. An interesting feature of continuous and smooth transition of the electric current density from the SIP to the SWP (with finite positive divergence on both the scales) through the SSB under inhomogeneous temperature distribution is also reported. Finally, the analyses may be applied to understand the realistic equilibrium dynamics of stellar plasmas never addressed before within the earlier GES framework like establishment of current-field correlation, properties of the slow solar wind and its

  6. No Pixel Left Behind - Peeling Away NASA's Satellite Swaths

    NASA Astrophysics Data System (ADS)

    Cechini, M. F.; Boller, R. A.; Schmaltz, J. E.; Roberts, J. T.; Alarcon, C.; Huang, T.; McGann, M.; Murphy, K. J.

    2014-12-01

    Discovery and identification of Earth Science products should not be the majority effort of scientific research. Search aides based on text metadata go to great lengths to simplify this process. However, the process is still cumbersome and requires too much data download and analysis to down select to valid products. The EOSDIS Global Imagery Browse Services (GIBS) is attempting to improve this process by providing "visual metadata" in the form of full-resolution visualizations representing geophysical parameters taken directly fromt he data. Through the use of accompanying interpretive information such as color legends and the natural visual processing of the human eye, researchers are able to search and filter through data products in a more natural and efficient way. The GIBS "visual metadata" products are generated as representations of Level 3 data or as temporal composites of the Level 2 granule- or swath-based data products projected across a geographic or polar region. Such an approach allows for low-latency tiled access to pre-generated imagery products. For many GIBS users, the resulting image suffices for a basic representation of the underlying data. However, composite imagery presents an insurmountable problem: for areas of spatial overlap within the composite, only one observation is visually represented. This is especially problematic in the polar regions where a significant portion of sensed data is "lost." In response to its user community, the GIBS team coordinated with its stakeholders to begin developing an approach to ensure that there is "no pixel left behind." In this presentation we will discuss the use cases and requirements guiding our efforts, considerations regarding standards compliance and interoperability, and near term goals. We will also discuss opportunities to actively engage with the GIBS team on this topic to continually improve our services.

  7. APPARATUS FOR SHEATHING RODS

    DOEpatents

    Ford, W.K.; Wyatt, M.; Plail, S.

    1961-08-01

    An arrangement is described for sealing a solid body of nuclear fuel, such as a uranium metal rod, into a closelyfitting thin metallic sheath with an internal atmosphere of inert gas. The sheathing process consists of subjecting the sheath, loaded with the nuclear fuel body, to the sequential operations of evacuation, gas-filling, drawing (to entrap inert gas and secure close contact between sheath and body), and sealing. (AEC)

  8. Communication through plasma sheaths

    SciTech Connect

    Korotkevich, A. O.; Newell, A. C.; Zakharov, V. E.

    2007-10-15

    We wish to transmit messages to and from a hypersonic vehicle around which a plasma sheath has formed. For long distance transmission, the signal carrying these messages must be necessarily low frequency, typically 2 GHz, to which the plasma sheath is opaque. The idea is to use the plasma properties to make the plasma sheath appear transparent.

  9. RF Sheath Models

    NASA Astrophysics Data System (ADS)

    D'Ippolito, D. A.; Myra, J. R.

    2007-11-01

    RF sheath formation on the antennas and walls in ICRF-heated experiments can reduce the heating efficiency, limit the coupled power, and cause damage to plasma-facing structures. The sheaths are driven by a slow wave component of the rf field due to a mismatch between the magnetic field and the boundary (antenna or wall). Quantitative modeling of the highly nonlinear sheaths may now be feasible for the first time in massively-parallel-processing (MPP) codes developed in the RF SciDAC project. Recently, a new approach to sheath modeling was proposed,ootnotetextD.A. D'Ippolito and J.R. Myra, Phys. Plasmas 13, 102508 (2006). in which the sheath physics is incorporated into the RF wave computation by using a modified boundary condition (BC) on the RF fields in both wave propagation and antenna codes. Here, we illustrate the use of the sheath BC for near-field sheaths by a model calculation that includes electromagnetic effects and a simple antenna coupling model. Properties of the model (such as the role of sheath-plasma waves) and implications for antenna codes such as TOPICAootnotetextV. Lancellotti et al., Nucl. Fusion 46, S476 (2006). will be discussed.

  10. Plasma-Sheath Model

    NASA Astrophysics Data System (ADS)

    Riemann, Karl-Ulrich

    2012-10-01

    In typical gas discharges a quasineutral plasma is shielded from a negativ absorbing wall by a thin positive sheath that is nearly planar and collision-free. The subdivision of ``plasma'' and ``sheath'' was introduced by Langmuir and is based on a small ratio of the electron Debye lenghth λD to the dominant competing characteristic plasma length l. Depending on the special conditions, l may represent, e.g., the plasma extension, the ionization length, the ion mean free path, the ion gyro radius, or a geometric length. Strictly speaking, this subdivion is possible only in the asymptotic limit λD/l->0. The asymptotic analysis results in singularities at the ``sheath edge'' closely related to the ``Bohm criterion.'' Due to these singularities a direct smooth matching of the separate plasma and sheath soltions is not possible. To obtain a consistent smooth transition, the singular sheath edge must be bridged by an additinal narrow ``intermediate'' model zone accounting both for plasma processes (e.g., collisions) and for the first build up of space charge. Due to this complexity and to different interpretations of the ``classical'' papers by Langmuir and Bohm, the asymptotic plasma-sheath concept and the definition of the sheath edge were questioned and resulted in controversies during the last two decades. We discuss attempts to re-define the sheath edge, to account for finite values of λD/l in the Bohm criterion, and demonstrate the consistent matching of plasma and sheath. The investigations of the plasma-sheath transition discussed so far are based on a simplified fluid analysis that cannot account for the essential inhomogeneity of the boundary layer and for the dominant role of slow ions in space charge formation. Therefore we give special emphasis to the kinetic theory of the plasma-sheath transition. Unfortunately this approach results in an additional mathematical difficulty caused by ions with zero velocity. We discuss attempts to avoid this singularity by

  11. Sheath energy transmission in a collisional plasma with collisionless sheath

    SciTech Connect

    Tang, Xian-Zhu Guo, Zehua

    2015-10-15

    Sheath energy transmission governs the plasma energy exhaust onto a material surface. The ion channel is dominated by convection, but the electron channel has a significant thermal conduction component, which is dominated by the Knudsen layer effect in the presence of an absorbing wall. First-principle kinetic simulations reveal a robustly supersonic sheath entry flow. The ion sheath energy transmission and the sheath potential are accurately predicted by a sheath model of truncated bi-Maxwellian electron distribution. The electron energy transmission is further enhanced by a parallel heat flux of the perpendicular degrees of freedom.

  12. Analytic Model of Antenna Sheaths

    NASA Astrophysics Data System (ADS)

    D'Ippolito, D. A.; Myra, J. R.

    2008-11-01

    RF sheaths are generated on ICRF antennas whenever the launched fast wave also drives a slow wave, e.g. when the magnetic field is tilted (not perpendicular to the current straps). A new approach to sheath modeling was recently proposed in which the RF waves are computed using a modified boundary condition at the sheath surface to describe the plasma-sheath coupling. Here, we illustrate the use of the sheath BC for antenna sheaths by a model electromagnetic perturbation calculation, treating the B field tilt as a small parameter. Analytic expressions are obtained for the sheath voltage and the rf electric field parallel to B in both sheath and plasma regions, including the Child-Langmuir (self-consistency) constraint. It is shown that the plasma corrections to the sheath voltage (which screen the rf field) can be important. The simple vacuum-field sheath-voltage estimate is obtained as a limiting case. Implications for antenna codes such as TOPICA will be discussed. D.A. D'Ippolito and J.R. Myra, Phys. Plasmas 13, 102508 (2006). V. Lancellotti et al., Nucl. Fusion 46, S476 (2006).

  13. 21 CFR 884.5320 - Glans sheath.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... sheath. (a) Identification. A glans sheath device is a sheath which covers only the glans penis or part... the entire shaft of the penis. It is indicated only for the prevention of pregnancy and not for...

  14. 21 CFR 884.5320 - Glans sheath.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... sheath. (a) Identification. A glans sheath device is a sheath which covers only the glans penis or part... the entire shaft of the penis. It is indicated only for the prevention of pregnancy and not for...

  15. 21 CFR 884.5320 - Glans sheath.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... sheath. (a) Identification. A glans sheath device is a sheath which covers only the glans penis or part... the entire shaft of the penis. It is indicated only for the prevention of pregnancy and not for...

  16. Challenging diagnosis of peripillous sheaths.

    PubMed

    Gnarra, Maria; Saraceni, Pierluigi; Rossi, Alfredo; Murabit, Amera; Caradonna, Emanuela; Fania, Luca; Feliciani, Claudio

    2014-01-01

    Peripillous sheaths, or hair casts, are asymptomatic, white, cylindrical concretions that encircle the hair without adhering to it. They are infrequently documented in the literature, are often misdiagnosed, and generate avoidable apprehension and expense for parents and caregivers. Dermoscopy is the standard for a rapid, noninvasive, cost-effective diagnosis. We describe a case of peripillous sheaths presenting in a boy. PMID:24846654

  17. Sheaths: A Comparison of Magnetospheric, ICME, and Heliospheric Sheaths

    NASA Technical Reports Server (NTRS)

    Sibeck, D. G.; Richardson, J. D.; Liu, W.

    2007-01-01

    When a supersonic flow encounters an obstacles, shocks form to divert the flow around the obstacle. The region between the shock and the obstacle is the sheath, where the supersonic flow is compressed, heated, decelerated, and deflected. Supersonic flows, obstacles, and thus sheaths are observed on many scales throughout the Universe. We compare three examples seen in the heliosphere, illustrating the interaction of the solar wind with obstacles of three very different scales lengths. Magnetosheaths form behind planetary bow shocks on scales ranging from tens to 100 planetary radii. ICME sheath form behind shocks driven by solar disturbances on scale lengths of a few to tens of AU. The heliosheath forms behind the termination shock due to the obstacle presented by the interstellar medium on scale lengths of tens to a hundred AU. Despite this range in scales some common features have been observed. Magnetic holes, possibly due to mirror mode waves, have been observed in all three of these sheaths. Plasma depletion layers are observed in planetary and ICME sheaths. Other features observed in some sheaths are wave activity (ion cyclotron, plasma), energetic particles, transmission of Alfven waves/shocks, tangential discontinuities turbulence behind quasi-parallel shocks, standing slow mode waves, and reconnection on the obstacle boundary. We compare these sheath regions, discussing similarities and differences and how these may relate to the scale lengths of these regions.

  18. Laminated magnet field coil sheath

    DOEpatents

    Skaritka, John R.

    1987-12-01

    a method for manufacturing a magnet cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible sheath, with the trim coil pattern precisely positioned thereon, is accurately positioned at a precise location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator.

  19. Laminated magnet field coil sheath

    DOEpatents

    Skaritka, J.R.

    1987-05-15

    A method for manufacturing a magnetic cable trim coil in a sheath assembly for use in a cryogenic particle accelerator. A precisely positioned pattern of trim coil turns is bonded to a flexible substrate sheath that is capable of withstanding cryogenic operating conditions. In the method of the invention the flexible substrate sheath, with the trim coil pattern precisely location relative to a bore tube assembly of an accelerator and is then bonded to the bore tube with a tape suitable for cryogenic application. The resultant assembly can be readily handled and installed within an iron magnet yoke assembly of a suitable cryogenic particle accelerator. 1 fig.

  20. Modeling Sheaths in DC Discharges

    NASA Astrophysics Data System (ADS)

    Robertson, Scott

    2014-10-01

    Textbook presentations on sheaths are often limited to a discussion of Bohm's criterion because more detailed analysis results in equations that can be solved only by numerical methods. There are both fluid and kinetic models for sheaths that can be solved by packaged numerical integration routines in a mathematical spreadsheet such as Mathematica, Matlab, or Mathcad. The potential profiles and the currents for sheaths at boundaries usually have monotonic profiles that are easily modeled using a Boltzmann distribution for electrons and for ions using the fluid momentum equation and the continuity equation with a source term describing plasma production. Additional ion species and bi-Maxwellian electron distributions are easily included. Virtual cathodes may form above emissive surfaces which divide the distribution function of emitted electrons into a passing population and a reflected population that can be modeled only by a kinetic approach. For sheaths at inserted objects such as probes and dust particles, it is customary to prescribe the plasma characteristics at infinity, to ignore creation of new plasma by ionization, and to solve for the radial variation of the density near the object and for the current collected by the object. A kinetic model is required for sheaths at inserted objects because the distribution function must be divided into passing particles and collected particles.

  1. Malignant Peripheral Nerve Sheath Tumor.

    PubMed

    James, Aaron W; Shurell, Elizabeth; Singh, Arun; Dry, Sarah M; Eilber, Fritz C

    2016-10-01

    Malignant peripheral nerve sheath tumor (MPNST) is the sixth most common type of soft tissue sarcoma. Most MPNSTs arise in association with a peripheral nerve or preexisting neurofibroma. Neurofibromatosis type is the most important risk factor for MPNST. Tumor size and fludeoxyglucose F 18 avidity are among the most helpful parameters to distinguish MPNST from a benign peripheral nerve sheath tumor. The histopathologic diagnosis is predominantly a diagnosis of light microscopy. Immunohistochemical stains are most helpful to distinguish high-grade MPNST from its histologic mimics. Current surgical management of high-grade MPNST is similar to that of other high-grade soft tissue sarcomas. PMID:27591499

  2. Cascaded target normal sheath acceleration

    SciTech Connect

    Wang, W. P.; Shen, B. F.; Zhang, X. M.; Wang, X. F.; Xu, J. C.; Zhao, X. Y.; Yu, Y. H.; Yi, L. Q.; Shi, Y.; Zhang, L. G.; Xu, T. J.; Xu, Z. Z.

    2013-11-15

    A cascaded target normal sheath acceleration (TNSA) scheme is proposed to simultaneously increase energy and improve energy spread of a laser-produced mono-energetic proton beam. An optimum condition that uses the maximum sheath field to accelerate the center of the proton beam is theoretically found and verified by two-dimensional particle-in-cell simulations. An initial 10 MeV proton beam is accelerated to 21 MeV with energy spread decreased from 5% to 2% under the optimum condition during the process of the cascaded TNSA. The scheme opens a way to scale proton energy lineally with laser energy.

  3. Silver-sheathed multifilament wires

    NASA Astrophysics Data System (ADS)

    Wu, C. T.; Goretta, K. C.; Shi, D.; Lanagan, M. T.; Poeppel, R. B.

    1991-01-01

    The process for manufacturing Ag-sheathed multifilament superconducting wires was investigated. Bi2Sr(1.7)CaCu2O(x), Pb-doped Bi2Sr2Ca2Cu3O(x), or YBa2Cu3O(x) powders were packed into Ag tubes and swaged into long wires. Pieces were cut from each wire, packed into a second Ag tube and swaged or rolled into multifilament wires. Each wire was then sintered to produce a superconductor. Processing considerations included the sheath workability, effects of compacting and residual stresses, and heat treatment schedules. The superconducting properties of the Bi-based wires were superior to those of the YBa2Cu3O(x) wires at 4.2 K, but not at 77 K.

  4. Modeling of dynamic bipolar plasma sheaths

    NASA Astrophysics Data System (ADS)

    Grossmann, J. M.; Swanekamp, S. B.; Ottinger, P. F.

    1992-01-01

    The behavior of a one-dimensional plasma sheath is described in regimes where the sheath is not in equilibrium because it carries current densities that are either time dependent, or larger than the bipolar Child-Langmuir level determined from the injected ion flux. Earlier models of dynamic bipolar sheaths assumed that ions and electrons evolve in a series of quasiequilibria. In addition, sheath growth was described by the equation Zen0ẋs=‖ ji‖-Zen0u0, where ẋs is the velocity of the sheath edge, ji is the ion current density, n0u0 is the injected ion flux density, and Ze is the ion charge. In this paper, a generalization of the bipolar electron-to-ion current density ratio formula is derived to study regimes where ions are not in equilibrium. A generalization of the above sheath growth equation is also developed, which is consistent with the ion continuity equation and which reveals new physics of sheath behavior associated with the emitted electrons and their evolution. Based on these findings, two new models of dynamic bipolar sheaths are developed. Larger sheath sizes and potentials than those of earlier models are found. In certain regimes, explosive sheath growth is predicted.

  5. Gold ink coating of thermocouple sheaths

    DOEpatents

    Ruhl, H. Kenneth

    1992-01-01

    A method is provided for applying a gold ink coating to a thermocouple sheath which includes the steps of electropolishing and oxidizing the surface of the thermocouple sheath, then dipping the sheath into liquid gold ink, and finally heat curing the coating. The gold coating applied in this manner is highly reflective and does not degrade when used for an extended period of time in an environment having a temperature over 1000.degree. F. Depending on the application, a portion of the gold coating covering the tip of the thermocouple sheath is removed by abrasion.

  6. Theory and simulation of plasma sheath waves

    SciTech Connect

    Xu, X.Q.; DiPeso, G.; Vahedi, V.; Birdsall, C.K.

    1992-12-15

    Sheath waves have been investigated analytically and with particle simulation for an unmagnetized two dimensional plasma slab with periodic boundary conditions in y and conducting walls at x = 0, L{sub x}. Analytically treating the sheath as a vacuum layer, the sheath wave bears a resemblance to plasma vacuum surface waves. The simulations are in agreement with the theory for both bulk Bohm Grow waves and edge sheath waves, with some unanswered questions. Some waves that were expected did not show up, at least, where we thought they should be. Hence, improvements were made in the initialization (a better quiet start), in the diagnostics (especially the spectra in frequency), and in the excitation (ability to pulse). It has become clear that this problem, seeking both sheath (or surface) and body waves in a bounded system, needs far more attention, in analysis (non-uniform density included) and in simulation, especially in diagnostics. Hence, this report is to be treated as a start on the problem. The problem is not dropped, as the understanding of such waves (in 2d and 3d) is very important, for both basic sheath understanding and for applications, such as plasma control via excitation of sheath or pre-sheath waves.

  7. SHEATH BLIGHT RESISTANCE IN SOUTHERN RICE

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight is a serious fungal disease problem in southern US rice production, making it necessary for rice farmers to diligently use fungicides for its control. There are no long grain rice varieties adapted to commercial production in the southern US that have adequate resistance to sheath bli...

  8. Unusual stability of the Methanospirillum hungatei sheath.

    PubMed Central

    Beveridge, T J; Stewart, M; Doyle, R J; Sprott, G D

    1985-01-01

    The proteinaceous sheath of Methanospirillum hungatei was isolated by lysing cells in 50 mM dithiothreitol, separating the sheath from other cellular material by discontinuous sucrose density centrifugation, and removing the "cell spacers" with dilute NaOH. The isolated sheath material consisted of hollow tubes which had a highly ordered surface array. The stability of the sheath to treatment with denaturants and to enzymatic digestion was examined by a turbidimetric assay in conjunction with electron microscopy and optical or electron diffraction. The sheath was resistant to a range of proteases and also was not digested by peptidoglycan-degrading enzymes, a lipase, a cellulase, a glucosidase, or Rhozyme (a mixture of galactosidases, acetylglucosaminidase, acetylgalactosaminidase, fucosidase, and mannosidases). In addition to being unaffected by common salts, thiol-reducing agents, and EDTA, the layer was resistant to powerful denaturants such as 6 M urea, 6 M guanidinium hydrochloride, 10 M LiSCN, cyanogen bromide, sodium periodate, and 1% sodium dodecyl sulfate. Strong bases, boiling 3 N HCl, and performic acid did attack the sheath; in these cases, the array was systematically disassembled in a progressive manner, which was followed by electron microscopy. The layer was slightly modified by N-bromosuccinimide in urea, but the array remained intact. The stability of the sheath was remarkable, not only as compared to other bacterial surface arrays, but also as compared to proteins generally, and possibly indicated the presence of covalent cross-links between protein subunits. Images PMID:3988711

  9. Disposable sheath that facilitates endoscopic Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Wang, Wenbo; Short, Michael; Tai, Isabella T.; Zeng, Haishan

    2016-02-01

    In vivo endoscopic Raman spectroscopy of human tissue using a fiber optic probe has been previously demonstrated. However, there remain several technical challenges, such as a robust control over the laser radiation dose and measurement repeatability during endoscopy. A decrease in the signal to noise was also observed due to aging of Raman probe after repeated cycles of harsh reprocessing procedures. To address these issues, we designed and tested a disposable, biocompatible, and sterile sheath for use with a fiber optic endoscopic Raman probe. The sheath effectively controls contamination of Raman probes between procedures, greatly reduces turnaround time, and slows down the aging of the Raman probes. A small optical window fitted at the sheath cap maintained the measurement distance between Raman probe end and tissue surface. To ensure that the sheath caused a minimal amount of fluorescence and Raman interference, the optical properties of materials for the sheath, optical window, and bonding agent were studied. The easy-to-use sheath can be manufactured at a moderate cost. The sheath strictly enforced a maximum permissible exposure standard of the tissue by the laser and reduced the spectral variability by 1.5 to 8.5 times within the spectral measurement range.

  10. Optical properties of nonextensive inhomogeneous plasma sheath

    NASA Astrophysics Data System (ADS)

    Mousavi, A.; Esfandiari-Kalejahi, A.; Akbari-Moghanjoughi, M.

    2016-07-01

    Propagation of electromagnetic wave through an inhomogeneous magnetized nonextensive plasma sheath is numerically examined for a realistic density profile of a reentry problem around a hypersonic vehicle. The effect of nonextensivity and inhomogeneity on radio wave communication is studied parametrically. Variation of reflection and transmission coefficients, total attenuation, and total phase shift over the plasma sheath with respect to the strength of applied magnetic field are derived and compared for different values of q-nonextensive parameter. The obtained results for inhomogeneous plasma sheath are compared with previously obtained results of authors for homogeneous plasma sheath. The comparison shows that radio communication in the inhomogeneous plasma sheath is more advantageous than that in the homogeneous case. The transmission coefficient of a plasma sheath with superthermal electrons ( /1 3 < q < 1 ) has larger value compared to that with q > 1. Moreover, for ω c e > ω , the minimum value of total attenuation corresponds to the range /1 3 < q < 1 . An interesting result is that nonextensivity effect on wave propagation in plasma sheath depends on the strength of the ambient magnetic field. The effect of nonextensivity on attenuation coefficient is found to be negligible for ω c e < ω while it is significant for ω c e > ω .

  11. Theory of the electron sheath and presheath

    SciTech Connect

    Scheiner, Brett; Baalrud, Scott D.; Yee, Benjamin T.; Hopkins, Matthew M.; Barnat, Edward V.

    2015-12-30

    Here, electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell(PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions (Te >> Ti), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic instabilities excited by the differential flow between electrons and ions in the presheath, which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.

  12. Theory of the electron sheath and presheath

    DOE PAGESBeta

    Scheiner, Brett; Baalrud, Scott D.; Yee, Benjamin T.; Hopkins, Matthew M.; Barnat, Edward V.

    2015-12-30

    Here, electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell(PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperaturemore » plasma conditions (Te >> Ti), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic instabilities excited by the differential flow between electrons and ions in the presheath, which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.« less

  13. Theory of the electron sheath and presheath

    NASA Astrophysics Data System (ADS)

    Scheiner, Brett; Baalrud, Scott D.; Yee, Benjamin T.; Hopkins, Matthew M.; Barnat, Edward V.

    2015-12-01

    Electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the electron velocity distribution function (EVDF). This work provides a dedicated theory of electron sheaths, which suggests that they are not so simple. Motivated by EVDFs observed in particle-in-cell (PIC) simulations, a 1D model for the electron sheath and presheath is developed. In the model, under low temperature plasma conditions ( Te≫Ti ), an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient generates large flow velocities compared to what would be generated by ballistic motion in response to the electric field. It is found that in many situations, under common plasma conditions, the electron presheath extends much further into the plasma than an analogous ion presheath. PIC simulations reveal that the ion density in the electron presheath is determined by a flow around the electron sheath and that this flow is due to 2D aspects of the sheath geometry. Simulations also indicate the presence of ion acoustic instabilities excited by the differential flow between electrons and ions in the presheath, which result in sheath edge fluctuations. The 1D model and time averaged PIC simulations are compared and it is shown that the model provides a good description of the electron sheath and presheath.

  14. Side-welded fast response sheathed thermocouple

    DOEpatents

    Carr, Kenneth R.

    1981-01-01

    A method of fabricating the measuring junction of a grounded-junction sheathed thermocouple to obtain fast time response and good thermal cycling performance is provided. Slots are tooled or machined into the sheath wall at the measuring junction, the thermocouple wires are laser-welded into the slots. A thin metal closure cap is then laser-welded over the end of the sheath. Compared to a conventional grounded-junction thermocouple, the response time is 4-5 times faster and the thermal shock and cycling capabilities are substantially improved.

  15. Side-welded fast response sheathed thermocouple

    DOEpatents

    Carr, K.R.

    A method of fabricating the measuring junction of a grounded-junction sheathed thermocouple to obtain fast time response and good thermal cycling performance is provided. Slots are tooled or machined into the sheath wall at the measuring junction, the thermocouple wires are laser-welded into the slots. A thin metal closure cap is then laser-welded over the end of the sheath. Compared to a conventional grounded-junction thermocouple, the response time is 4 to 5 times faster and the thermal shock and cycling capabilities are substantially improved.

  16. Effects of electron emission on sheath potential

    NASA Astrophysics Data System (ADS)

    Dow, Ansel; Khrabrov, Alexander; Kaganovich, Igor; Schamis, Hanna

    2015-11-01

    We investigate the potential profile of a sheath under the influence of surface electron emission. The plasma and sheath profiles are simulated using the Large Scale Plasma (LSP) particle-in-cell code. Using one dimensional models we corroborate the analytical relationship between sheath potential and plasma electron and emitted electron temperatures derived earlier. This work was made possible by funding from the Department of Energy for the Summer Undergraduate Laboratory Internship (SULI) program. This work is supported by the US DOE Contract No. DE-AC02-09CH11466.

  17. Rectus sheath hematoma: three case reports

    PubMed Central

    Kapan, Selin; Turhan, Ahmet N; Alis, Halil; Kalayci, Mustafa U; Hatipoglu, Sinan; Yigitbas, Hakan; Aygun, Ersan

    2008-01-01

    Introduction Rectus sheath hematoma is an uncommon cause of acute abdominal pain. It is an accumulation of blood in the sheath of the rectus abdominis, secondary to rupture of an epigastric vessel or muscle tear. It could occur spontaneously or after trauma. They are usually located infraumblically and often misdiagnosed as acute abdomen, inflammatory diseases or tumours of the abdomen. Case presentation We reported three cases of rectus sheath hematoma presenting with a mass in the abdomen and diagnosed by computerized tomography. The patients recovered uneventfully after bed rest, intravenous fluid replacement, blood transfusion and analgesic treatment. Conclusion Rectus sheath hematoma is a rarely seen pathology often misdiagnosed as acute abdomen that may lead to unnecessary laparotomies. Computerized tomography must be chosen for definitive diagnosis since ultrasonography is subject to error due to misinterpretation of the images. Main therapy is conservative management. PMID:18221529

  18. Malignant Peripheral Nerve Sheath Tumors.

    PubMed

    Durbin, Adam D; Ki, Dong Hyuk; He, Shuning; Look, A Thomas

    2016-01-01

    Malignant peripheral nerve sheath tumors (MPNST) are tumors derived from Schwann cells or Schwann cell precursors. Although rare overall, the incidence of MPNST has increased with improved clinical management of patients with the neurofibromatosis type 1 (NF1) tumor predisposition syndrome. Unfortunately, current treatment modalities for MPNST are limited, with no targeted therapies available and poor efficacy of conventional radiation and chemotherapeutic regimens. Many murine and zebrafish models of MPNST have been developed, which have helped to elucidate the genes and pathways that are dysregulated in MPNST tumorigenesis, including the p53, and the RB1, PI3K-Akt-mTOR, RAS-ERK and Wnt signaling pathways. Preclinical results have suggested that new therapies, including mTOR and ERK inhibitors, may synergize with conventional chemotherapy in human tumors. The discovery of new genome editing technologies, like CRISPR-cas9, and their successful application to the zebrafish model will enable rapid progress in the faithful modeling of MPNST molecular pathogenesis. The zebrafish model is especially suited for high throughput screening of new targeted therapeutics as well as drugs approved for other purposes, which may help to bring enhanced treatment modalities into human clinical trials for this devastating disease. PMID:27165368

  19. Sheath rot of rice in Iran.

    PubMed

    Naeimi, S; Okhovvat, S M; Hedjaroude, G A; Khosravi, V

    2003-01-01

    Sheath rot of rice occurs in most rice-growing regions of the world. It usually causes yield losses from 20 to 85%. Sheath rot was reported from Iran in 1993. Year after year, the number of diseased plants increased in the Northern Iran. In summer of 2001, these symptoms were observed in most fields: lesions occur on the upper leaf sheaths, especially the flag leaf sheath. As the disease progresses, lesions enlarge and coalesce and may cover most of the leaf sheath. Panicle may fail to completely or at all. Brown or partially brown not filled or partially filled grain is also associated with infection of the panicle. A whitish powdery growth may be found inside affected sheaths. Infected plants were collected and trasferred to laboratory. Small pieces of diseased tissues were washed under tap water for one hour. Then tissues were placed on WA and incubated at 25 degrees C. These isolates were purified and identified as: Sarocladium oryzae, Fusarium udum, F. semitectum, F. avenaceum, F. flocciferum, F. graminearum, Bipolaris oryzae, Alternaria padwickii, Rhizoctonia solani, Paecilomyces sp., Nigrospora sp. and Trichoderma sp. This is the first report of F. udum in Iran. Also this is the first report that rice is the host for F. semitectum, F. avenaceum and F. flocciferum in Iran. Pathogenicity tests were conducted in glass house. Following species were found to be associated with sheath rot of rice: S. oryzae, F. graminearum, F. udum, F. avenaceum, B. oryzae, A. padwickii. This is the first report in the world that F. udum and A. padwickii are the causal agents of the sheath rot on rice plants. PMID:15151303

  20. Multidimensional Plasma Sheaths over Electrically Inhomogeneous Surfaces

    NASA Astrophysics Data System (ADS)

    Economou, Demetre

    2004-09-01

    Multidimensional plasma sheaths are encountered in a number of applications including plasma immersion ion implantation, extraction of ions (or plasma) through grids, MEMS fabrication, neutral beam sources, and plasma in contact with internal reactor parts (e.g., wafer chuck edge). The sheath may be multidimensional when: (a) plasma is in contact with surface topography, and the size of the topographical features is comparable to or larger than the plasma sheath thickness, or (b) the surface is flat but inhomogeneous, i.e., a conducting surface next to an insulating surface. In either case, the flux, energy and angular distributions of energetic species incident on the substrate are of primary importance. These quantities depend critically on the shape of the meniscus (plasma-sheath boundary) formed over the surface. A two-dimensional fluid/Monte Carlo simulation model was developed to study multidimensional sheaths. The radio frequency (RF) sheath potential evolution, and ion density and flux profiles over the surface were predicted with a self-consistent fluid simulation. The trajectories of ions and energetic neutrals (resulting by ion neutralization on surfaces or charge exchange collisions in the gas phase) were then followed with a Monte Carlo simulation. Ion flow and energy and angular distributions of ions bombarding a flat but electrically inhomogeneous surface will be reported in detail. Ion flow over trenches and holes will also be reported. Work supported by the NSF, Sandia National Laboratories and NIST.

  1. Protective sheath for a continuous measurement thermocouple

    DOEpatents

    Phillippi, R.M.

    1991-12-03

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device. 4 figures.

  2. Protective sheath for a continuous measurement thermocouple

    DOEpatents

    Phillippi, R. Michael

    1991-01-01

    Disclosed is a protective thermocouple sheath of a magnesia graphite refractory material for use in continuous temperature measurements of molten metal in a metallurgical ladle and having a basic slag layer thereon. The sheath includes an elongated torpedo-shaped sheath body formed of a refractory composition and having an interior borehole extending axially therethrough and adapted to receive a thermocouple. The sheath body includes a lower end which is closed about the borehole and forms a narrow, tapered tip. The sheath body also includes a first body portion integral with the tapered tip and having a relatively constant cross section and providing a thin wall around the borehole. The sheath body also includes a second body portion having a relatively constant cross section larger than the cross section of the first body portion and providing a thicker wall around the borehole. The borehole terminates in an open end at the second body portion. The tapered tip is adapted to penetrate the slag layer and the thicker second body portion and its magnesia constituent material are adapted to withstand chemical attack thereon from the slag layer. The graphite constituent improves thermal conductivity of the refractory material and, thus, enhances the thermal responsiveness of the device.

  3. Theory of the Electron Sheath and Presheath

    NASA Astrophysics Data System (ADS)

    Scheiner, Brett; Baalrud, Scott; Yee, Benjamin; Hopkins, Matthew; Barnat, Edward

    2015-09-01

    Electron sheaths are commonly found near Langmuir probes collecting the electron saturation current. The common assumption is that the probe collects the random flux of electrons incident on the sheath, which tacitly implies that there is no electron presheath and that the flux collected is due to a velocity space truncation of the velocity distribution function (VDF). This work provides a dedicated theory of electron sheaths, which suggests that electron sheaths are not so simple. Motivated by VDFs observed in recent Particle-In-Cell (PIC) simulations, we develop a 1D model for the electron sheath and presheath. In the model, under low temperature plasma conditions, an electron pressure gradient accelerates electrons in the presheath to a flow velocity that exceeds the electron thermal speed at the sheath edge. This pressure gradient allows the generation of large flows compared to those that would be generated by the electric field alone. It is due to this pressure gradient that the electron presheath extends much further into the plasma (nominally by a factor of √{mi /me }) than an analogous ion presheath. Results of the model are compared with PIC simulations. This work was supported by the Office of Fusion Energy Science at the U.S. Department of Energy under contract DE-AC04-94SL85000 and by the Office of Science Graduate Student Research (SCGSR) program under Contract Number DE-AC05-06OR23100.

  4. How to Patch Active Plasma and Collisionless Sheath: Practical Guide

    SciTech Connect

    Kaganovich, Igor D.

    2002-08-22

    Most plasmas have a very thin sheath compared with the plasma dimension. This necessitates separate calculations of the plasma and sheath. The Bohm criterion provides the boundary condition for calculation of plasma profiles. To calculate sheath properties, a value of electric field at the plasma-sheath interface has to be specified in addition to the Bohm criterion. The value of the boundary electric field and robust procedure to approximately patch plasma and collisionless sheath with a very good accuracy are reported.

  5. Sheaths: More complicated than you think

    SciTech Connect

    Hershkowitz, Noah

    2005-05-15

    Sheaths in low temperature collisionless and weakly collisional plasmas are often viewed as simple examples of nonlinear physics. How well do we understand them? Closer examination indicates that they are far from simple. Moreover, many predicted sheath properties have not been experimentally verified and even the appropriate 'Bohm velocity' for often encountered two-ion species plasma is unknown. In addition, a variety of sheathlike structures, e.g., double layers, can exist, and many two- and three-dimensional sheath effects have not been considered. Experimental studies of sheaths and presheaths in weakly collisional plasmas are described. A key diagnostic is emissive probes operated in the 'limit of zero emission'. Emissive probes provide a sensitive diagnostic of plasma potential with a resolution approaching 0.1 V and a spatial resolution of 0.1 cm. Combined with planar Langmuir probes and laser-induced fluorescence, they have been used to investigate a wide variety of sheath, presheath, and sheathlike structures. Our experiments have provided some answers but have also raised more questions.

  6. Polarization force-induced changes in the dust sheath formation

    SciTech Connect

    Mayout, Saliha; Bentabet, Karima; Tribeche, Mouloud

    2015-09-15

    The modifications arising in the dusty plasma sheath structure due to the presence of polarization forces acting on the dust grains are investigated. The corresponding appropriate Bohm criterion for sheath formation is obtained. It is found that the critical Mach number, beyond which the dusty plasma electrostatic sheath sets in, decreases whenever the polarization effects become important. In addition, when the polarization force dominates over the electrical one, the dust plasma sheath cannot set in. This happens whenever the dust grain size exceeds a critical threshold. Moreover, the sheath electrostatic potential-gradient becomes abruptly steep, and the sheath thickness becomes broader as the polarization force effects strengthen.

  7. Accuracy of the Unified Sheath Model

    NASA Astrophysics Data System (ADS)

    Riley, Merle E.

    1997-10-01

    The Unified Sheath Model ( M. E. Riley, Sandia Labs Tech Reports SAND95-0775 UC-401 (May, 1995) and SAND96-1948 UC-401 (August, 1996)) is designed to bridge the intermediate region of ion response between the high frequency Lieberman model and the low frequency Metze, Ernie, and Oskam model. In order to make a quantitative check of the effective ion response time (inverse ion plasma radian frequency at the presheath boundary), I have compared the semi-analytic Unified Model predictions to time- and space-dependent numerical solutions of the ion fluid equations in an rf-biased plasma sheath. In so doing, one is testing the most crucial of the physical approximations made in the model. The comparisons are good and lend confidence to use of the sheath model in the simulation of rf-biased plasmas in processing applications.

  8. 56. POWDER MAGAZINE, VIEW OF INTACT WOOD SHEATHING ON THE ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    56. POWDER MAGAZINE, VIEW OF INTACT WOOD SHEATHING ON THE SOUTHWEST REAR VENTILATION PASSAGE. (SHEATHING HELP CONTROL HUMIDITY AND DECREASE DANGER OF MAETAL STRIKING STONE AND SPARKING.) - Fort Monroe, Fortress, Hampton, Hampton, VA

  9. Massive exophytic malignant peripheral nerve sheath tumor.

    PubMed

    Khorsand, Derek; Porrino, Jack; Flaherty, Erin; Bandhlish, Anshu; Davidson, Darin

    2016-06-01

    We present a case of a solitary neurofibroma involving the right posterior shoulder of a 69-year-old man with degeneration into a massive, malignant peripheral nerve sheath tumor measuring more than 3 times the average reported size. The radiographic, magnetic resonance imaging, and computed tomographic features are compared with the gross appearance and pathology. PMID:27257459

  10. Sheath fold morphology in simple shear

    NASA Astrophysics Data System (ADS)

    Reber, Jacqueline E.; Dabrowski, Marcin; Galland, Olivier; Schmid, Daniel W.

    2013-08-01

    Sheath folds are highly non-cylindrical structures often associated with shear zones. We investigate the formation of sheath folds around a weak inclusion acting as a slip surface in simple shear by means of an analytical model. We present results for different slip surface orientations and shapes. Cross-sections perpendicular to the shear direction through the sheath fold display closed contours, so called eye-structures. The aspect ratio of the outermost closed contour is strongly dependent on the initial slip surface configuration. The center of the eye-structure is subject to change in height with respect to the upper edge of the outermost closed contour for different cross-sections perpendicular to the shear direction. This results in a large variability in layer thickness across the sheath fold length, questioning the usefulness of eye-structures as shear sense indicators. The location of the center of the eye structure is largely invariant to the initial configurations of the slip surface as well as to strain. The values of the aspect ratios of the closed contours within the eye-pattern are dependent on the strain and the cross-section location. The ratio (R') of the aspect ratios of the outermost closed contour (Ryz) and the innermost closed contour (Ry'z') shows values above and below 1. R' shows dependence on the slip surface shape and orientation but not on the number of involved contours. Using R' measurements to deduce the bulk strain type may be erroneous.

  11. Radio-frequency sheath-plasma interactions with magnetic field tangency points along the sheath surface

    SciTech Connect

    Kohno, H.; Myra, J. R.; D'Ippolito, D. A.

    2013-08-15

    Computer simulations of radio-frequency (RF) waves propagating across a two-dimensional (2D) magnetic field into a conducting boundary are described. The boundary condition for the RF fields at the metal surface leads to the formation of an RF sheath, which has previously been studied in one-dimensional models. In this 2D study, it is found that rapid variation of conditions along the sheath surface promote coupling of the incident RF branch (either fast or slow wave) to a short-scale-length sheath-plasma wave (SPW). The SPW propagates along the sheath surface in a particular direction dictated by the orientation of the magnetic field with respect to the surface, and the wave energy in the SPW accumulates near places where the background magnetic field is tangent to the surface.

  12. 30 CFR 75.1314 - Sheathed explosive units.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... 30 Mineral Resources 1 2013-07-01 2013-07-01 false Sheathed explosive units. 75.1314 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1314 Sheathed explosive units. (a) A separate instantaneous detonator shall be used to fire each sheathed explosive...

  13. 30 CFR 75.1314 - Sheathed explosive units.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Sheathed explosive units. 75.1314 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1314 Sheathed explosive units. (a) A separate instantaneous detonator shall be used to fire each sheathed explosive...

  14. 30 CFR 75.1314 - Sheathed explosive units.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Sheathed explosive units. 75.1314 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1314 Sheathed explosive units. (a) A separate instantaneous detonator shall be used to fire each sheathed explosive...

  15. 30 CFR 75.1314 - Sheathed explosive units.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 30 Mineral Resources 1 2014-07-01 2014-07-01 false Sheathed explosive units. 75.1314 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1314 Sheathed explosive units. (a) A separate instantaneous detonator shall be used to fire each sheathed explosive...

  16. 30 CFR 75.1314 - Sheathed explosive units.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 30 Mineral Resources 1 2012-07-01 2012-07-01 false Sheathed explosive units. 75.1314 Section 75... HEALTH MANDATORY SAFETY STANDARDS-UNDERGROUND COAL MINES Explosives and Blasting § 75.1314 Sheathed explosive units. (a) A separate instantaneous detonator shall be used to fire each sheathed explosive...

  17. Effects of plasma sheath on solar power satellite array

    NASA Technical Reports Server (NTRS)

    Parker, L. W.

    1979-01-01

    The structure of the plasma sheath and equilibrium voltage distribution of a high-power solar array governs various kinds of plasma-interaction phenomena and array losses. Sheath effects of a linearly-connected array are investigated for GEO. Although the array may be large, the thin-sheath-limit analysis may be invalid, necessitating numerical methods. Three-dimensional computer calculations show that potential barriers and over-lapping sheaths can occur, i.e., structures not predictable under the thin-sheath-limit analysis, but nevertheless controlling the distribution of plasma currents impacting on the array.

  18. Male urinary incontinence and the urinary sheath.

    PubMed

    Smart, Clare

    This article addresses the assessment and management of male incontinence with a specific focus on the use of the male external catheter (MEC) or urinary sheath. Education and expertise when dealing with a man with urinary incontinence, as well as a tactful and sensitive attitude towards this embarrassing problem, are essential for a successful outcome. The urinary sheath is often perceived by nurses and patients as a difficult product to master and is prone to failure owing to incorrect fitting and management. With correct usage it can make a great difference to a patient's quality of life and avoid problems often associated with urinary catheters and pads such as urinary infection and skin excoriation. Detailed assessment of the patient as well as his suitability for the MEC is essential for a successful outcome. PMID:24820510

  19. Optic Nerve Sheath Mechanics in VIIP Syndrome

    NASA Technical Reports Server (NTRS)

    Raykin, Julia; Feola, Andrew; Gleason, Rudy; Mulugeta, Lealem; Myers, Jerry; Nelson, Emily; Samuels, Brian; Ethier, C. Ross

    2015-01-01

    Visual Impairment and Intracranial Pressure (VIIP) syndrome results in a loss of visual function and occurs in astronauts following long-duration spaceflight. Understanding the mechanisms that lead to the ocular changes involved in VIIP is of critical importance for space medicine research. Although the exact mechanisms of VIIP are not yet known, it is hypothesized that microgravity-induced increases in intracranial pressures (ICP) drive the remodeling of the optic nerve sheath, leading to compression of the optic nerve which in turn may reduce visual acuity. Some astronauts present with a kink in the optic nerve after return to earth, suggesting that tissue remodeling in response to ICP increases may be taking place. The goal of this work is to characterize the mechanical properties of the optic nerve sheath (dura mater) to better understand its biomechanical response to increased ICP.

  20. Anode sheath contributions in plasma thrusters

    NASA Astrophysics Data System (ADS)

    Riggs, John F.

    1994-03-01

    Contributions of the anode to Magnetoplasmadynamic (MPD) thruster performance are considered. High energy losses at this electrode, surface erosion, and sheath/ionization effects must be controlled in designs of practical interest. Current constriction or spotting at the anode, evolving into localized surface damage and considerable throat erosion, is shown to be related to the electron temperature's T(sub e) rise above the gas temperature T(sub o). An elementary one-dimensional description of a collisional sheath which highlights the role of T(sub e) is presented. Computations to model the one-dimensional sheath are attempted using a set of five coupled first-order, nonlinear differential equations describing the electric field, as well as the species current and number densities. For a large temperature nonequilibrium (i.e., T(sub e) greater than T(sub o)), the one-dimensional approach fails to give reasonable answers and a multidimensional description is deemed necessary. Thus, anode spotting may be precipitated by the elevation of T sub e among other factors. A review of transpiration cooling as a means of recouping some anode power is included. Active anode cooling via transpiration cooling would result in (1) quenching T(sub e), (2) adding 'hot' propellant to exhaust, and (3) reducing the local electron Hall parameter.

  1. Radio frequency sheaths in an oblique magnetic field

    DOE PAGESBeta

    Myra, James R.; D'Ippolito, Daniel A.

    2015-06-01

    The physics of radio-frequency (rf) sheaths near a conducting surface is studied for plasmas immersed in a magnetic field that makes an oblique angle θ with the surface. A set of one-dimensional equations is developed that describe the dynamics of the time-dependent magnetic presheath and non-neutral Debye sheath. The model employs Maxwell-Boltzmann electrons, and the magnetization and mobility of the ions is determined by the magnetic field strength, and wave frequency, respectively. The angle, θ assumed to be large enough to insure an electron-poor sheath, is otherwise arbitrary. Concentrating on the ion-cyclotron range of frequencies, the equations are solved numericallymore » to obtain the rectified (dc) voltage, the rf voltage across the sheath and the rf current flowing through the sheath. As an application of this model, the sheath voltage-current relation is used to obtain the rf sheath impedance, which in turn gives an rf sheath boundary condition for the electric field at the sheath-plasma interface that can be used in rf wave codes. In general the impedance has both resistive and capacitive contributions, and generalizes previous sheath boundary condition models. The resistive part contributes to parasitic power dissipation at the wall.« less

  2. Radio frequency sheaths in an oblique magnetic field

    SciTech Connect

    Myra, James R.; D'Ippolito, Daniel A.

    2015-06-01

    The physics of radio-frequency (rf) sheaths near a conducting surface is studied for plasmas immersed in a magnetic field that makes an oblique angle θ with the surface. A set of one-dimensional equations is developed that describe the dynamics of the time-dependent magnetic presheath and non-neutral Debye sheath. The model employs Maxwell-Boltzmann electrons, and the magnetization and mobility of the ions is determined by the magnetic field strength, and wave frequency, respectively. The angle, θ assumed to be large enough to insure an electron-poor sheath, is otherwise arbitrary. Concentrating on the ion-cyclotron range of frequencies, the equations are solved numerically to obtain the rectified (dc) voltage, the rf voltage across the sheath and the rf current flowing through the sheath. As an application of this model, the sheath voltage-current relation is used to obtain the rf sheath impedance, which in turn gives an rf sheath boundary condition for the electric field at the sheath-plasma interface that can be used in rf wave codes. In general the impedance has both resistive and capacitive contributions, and generalizes previous sheath boundary condition models. The resistive part contributes to parasitic power dissipation at the wall.

  3. Radio frequency sheaths in an oblique magnetic field

    SciTech Connect

    Myra, J. R.; D'Ippolito, D. A.

    2015-06-15

    The physics of radio-frequency (rf) sheaths near a conducting surface is studied for plasmas immersed in a magnetic field that makes an oblique angle θ with the surface. A set of one-dimensional equations is developed that describes the dynamics of the time-dependent magnetic presheath and non-neutral Debye sheath. The model employs Maxwell-Boltzmann electrons, and the magnetization and mobility of the ions is determined by the magnetic field strength, and wave frequency, respectively. The angle θ, assumed to be large enough to insure an electron-poor sheath, is otherwise arbitrary. Concentrating on the ion-cyclotron range of frequencies, the equations are solved numerically to obtain the rectified (dc) voltage, the rf voltage across the sheath, and the rf current flowing through the sheath. As an application of this model, the sheath voltage-current relation is used to obtain the rf sheath impedance, which in turn gives an rf sheath boundary condition for the electric field at the sheath-plasma interface that can be used in rf wave codes. In general, the impedance has both resistive and capacitive contributions, and generalizes previous sheath boundary condition models. The resistive part contributes to parasitic power dissipation at the wall.

  4. Radio frequency sheaths in an oblique magnetic field

    NASA Astrophysics Data System (ADS)

    Myra, J. R.; D'Ippolito, D. A.

    2015-06-01

    The physics of radio-frequency (rf) sheaths near a conducting surface is studied for plasmas immersed in a magnetic field that makes an oblique angle θ with the surface. A set of one-dimensional equations is developed that describes the dynamics of the time-dependent magnetic presheath and non-neutral Debye sheath. The model employs Maxwell-Boltzmann electrons, and the magnetization and mobility of the ions is determined by the magnetic field strength, and wave frequency, respectively. The angle θ, assumed to be large enough to insure an electron-poor sheath, is otherwise arbitrary. Concentrating on the ion-cyclotron range of frequencies, the equations are solved numerically to obtain the rectified (dc) voltage, the rf voltage across the sheath, and the rf current flowing through the sheath. As an application of this model, the sheath voltage-current relation is used to obtain the rf sheath impedance, which in turn gives an rf sheath boundary condition for the electric field at the sheath-plasma interface that can be used in rf wave codes. In general, the impedance has both resistive and capacitive contributions, and generalizes previous sheath boundary condition models. The resistive part contributes to parasitic power dissipation at the wall.

  5. Simulations of plasma sheaths using continuum kinetic models

    NASA Astrophysics Data System (ADS)

    Srinivasan, Bhuvana; Hakim, Ammar

    2015-11-01

    Understanding plasma sheath physics is important for the performance of devices such as Hall thrusters due to the effect of energetic particles on electrode erosion. Plasma sheath physics is studied using kinetic and multi-fluid models with relevance to secondary electron emissions and plasma-surface interactions. Continuum kinetic models are developed to directly solve the Vlasov-Poisson equation using the discontinuous Galerkin method for each of the ion and electron species. A steady-state sheath is simulated by including a simple model for a neutral fluid. Multi-fluid simulations for the plasma sheath are also performed using the discontinuous Galerkin method to solve a complete set of fluid equations for each of the ion and electron species. The kinetic plasma sheath is compared to a multi-fluid plasma sheath. Supported by Air Force Office of Scientific Research.

  6. Sheath insulator final test report, TFE Verification Program

    SciTech Connect

    Not Available

    1994-07-01

    The sheath insulator in a thermionic cell has two functions. First, the sheath insulator must electrically isolate the collector form the outer containment sheath tube that is in contact with the reactor liquid metal coolant. Second, The sheath insulator must provide for high uniform thermal conductance between the collector and the reactor coolant to remove away waste heat. The goals of the sheath insulator test program were to demonstrate that suitable ceramic materials and fabrication processes were available, and to validate the performance of the sheath insulator for TFE-VP requirements. This report discusses the objectives of the test program, fabrication development, ex-reactor test program, in-reactor test program, and the insulator seal specifications.

  7. Nerve sheath myxoma: report of a rare case.

    PubMed

    Bhat, Amoolya; Narasimha, Apaparna; C, Vijaya; Vk, Sundeep

    2015-04-01

    Nerve sheath myxoma defined by Harkin and Reed is an uncommon benign neoplasm with nerve sheath like features. It has several cytological and histological differential diagnoses. One such lesion is neurothekeoma, which can be differentiated using immunohistochemistry. In most of the previous reports nerve sheath myxoma and neurothekeoma were considered synonymous and were often confused for one another. This case report separates the two using immunohistochemistry. Also, the cytological features of nerve sheath myxoma are not well documented in the past. This case report attempts to display the cyto-morphology of nerve sheath myxoma. We report a rare case of nerve sheath myxoma diagnosed on cytological features confirmed by histopathology and immunohistochemistry in a 32-year-old lady who presented with an asymptomatic nodule over the left cervical area and discuss its cyto-histological mimics. PMID:26023558

  8. Kinetic model for the collisionless sheath of a collisional plasma

    NASA Astrophysics Data System (ADS)

    Tang, Xian-Zhu; Guo, Zehua

    2016-08-01

    Collisional plasmas typically have mean-free-path still much greater than the Debye length, so the sheath is mostly collisionless. Once the plasma density, temperature, and flow are specified at the sheath entrance, the profile variation of electron and ion density, temperature, flow speed, and conductive heat fluxes inside the sheath is set by collisionless dynamics, and can be predicted by an analytical kinetic model distribution. These predictions are contrasted here with direct kinetic simulations, showing good agreement.

  9. Detached tip of a transseptal sheath during left atrial ablation.

    PubMed

    El-Damaty, Ahmed; Love, Michael; Parkash, Ratika

    2012-02-15

    Left atrial ablation has become more commonplace with the advent of catheter ablation for atrial fibrillation. A number of transseptal sheaths have been produced to enhance safe and efficient catheter manipulation in the left atrium (LA) for these procedures. Some of the sheaths have been subject to recall due to partial or complete detachment of its radiopaque tip. We report a case of a 46 year-old female diagnosed with idiopathic dilated cardiomyopathy that presented with atypical left atrial flutter. During electrophysiologic study, a Swartz braided SL1 (SL-1) transseptal sheath was used to introduce the ablation catheter to the left atrium. During left atrial mapping, the radiopaque tip of the sheath detached from the rest of the sheath and was seen floating in the LA. After exchanging the SL-1 sheath with a deflectable sheath, the detached segment was retrieved out of the LA and eventually out of the vascular system using an angioplasty balloon advanced over a wire and inflated distal to the lumen of the detached tip. The root cause of this malfunction was found to be lack of a secondary bonding process that these sheaths generally undergo during the manufacturing process. We describe the case of a left atrial ablation procedure where a novel percutaneous method was able to successfully retrieve the detached tip of a transseptal sheath from the vascular system, thereby avoiding a potential catastrophic complication or thoracotomy. This method may be useful in other cases where similar circumstances may present. PMID:22162088

  10. Rarefaction solitons initiated by sheath instability

    SciTech Connect

    Levko, Dmitry

    2015-09-15

    The instability of the cathode sheath initiated by the cold energetic electron beam is studied by the one-dimensional fluid model. Numerical simulations show the generation of travelling rarefaction solitons at the cathode. It is obtained that the parameters of these solitons strongly depend on the parameters of electron beam. The “stretched” variables are derived using the small-amplitude analysis. These variables are used in order to obtain the Korteweg-de Vries equation describing the propagation of the rarefaction solitons through the plasma with cold energetic electron beam.

  11. Controversies in ureteroscopy: Wire, basket, and sheath

    PubMed Central

    Rizkala, Emad R; Monga, Manoj

    2013-01-01

    In the last one to two decades, flexible ureteroscopy has rapidly expanded its role in the treatment of urologic stone disease. With the frequent and expanded use of flexible ureteroscopy, other ancillary instruments were developed in order to ease and facilitate this technique, such as ureteral access sheaths (UAS) and a variety of wires and baskets. These developments, along with improved surgeon ureteroscopic competence, have often brought into question the need to implement the “traditional technique” of flexible ureteroscopy. In this review, we discuss a brief history of flexible ureteroscopy, its expanded indications, and the controversy surrounding the use of UAS, wires, and baskets. PMID:24082447

  12. Target normal sheath acceleration sheath fields for arbitrary electron energy distribution

    SciTech Connect

    Schmitz, Holger

    2012-08-15

    Relativistic electrons, generated by ultraintense laser pulses, travel through the target and form a space charge sheath at the rear surface which can be used to accelerate ions to high energies. If the laser pulse duration is comparable or shorter than the time needed for the electrons to travel through the target, the electrons will not have the chance to form an equilibrium distribution but must be described by a non-equilibrium distribution. We present a kinetic theory of the rear sheath for arbitrary electron distribution function f(E), where E is the electron energy, and evaluate it for different shapes of f(E). We find that the far field is mainly determined by the high energy tail of the distribution, a steep decay of f(E) for high energies results in a small electric field and vice versa. The model is extended to account for electrons escaping the sheath region thereby allowing a finite potential drop over the sheath. The consequences of the model for the acceleration of ions are discussed.

  13. CNS Myelin Sheath Lengths Are an Intrinsic Property of Oligodendrocytes

    PubMed Central

    Bechler, Marie E.; Byrne, Lauren; ffrench-Constant, Charles

    2015-01-01

    Summary Since Río-Hortega’s description of oligodendrocyte morphologies nearly a century ago, many studies have observed myelin sheath-length diversity between CNS regions [1–3]. Myelin sheath length directly impacts axonal conduction velocity by influencing the spacing between nodes of Ranvier. Such differences likely affect neural signal coordination and synchronization [4]. What accounts for regional differences in myelin sheath lengths is unknown; are myelin sheath lengths determined solely by axons or do intrinsic properties of different oligodendrocyte precursor cell populations affect length? The prevailing view is that axons provide molecular cues necessary for oligodendrocyte myelination and appropriate sheath lengths. This view is based upon the observation that axon diameters correlate with myelin sheath length [1, 5, 6], as well as reports that PNS axonal neuregulin-1 type III regulates the initiation and properties of Schwann cell myelin sheaths [7, 8]. However, in the CNS, no such instructive molecules have been shown to be required, and increasing in vitro evidence supports an oligodendrocyte-driven, neuron-independent ability to differentiate and form initial sheaths [9–12]. We test this alternative signal-independent hypothesis—that variation in internode lengths reflects regional oligodendrocyte-intrinsic properties. Using microfibers, we find that oligodendrocytes have a remarkable ability to self-regulate the formation of compact, multilamellar myelin and generate sheaths of physiological length. Our results show that oligodendrocytes respond to fiber diameters and that spinal cord oligodendrocytes generate longer sheaths than cortical oligodendrocytes on fibers, co-cultures, and explants, revealing that oligodendrocytes have regional identity and generate different sheath lengths that mirror internodes in vivo. PMID:26320951

  14. Anode Sheath Switching in a Carbon Nanotube Arc Plasma

    SciTech Connect

    Abe Fetterman, Yevgeny Raitses, and Michael Keidar

    2008-04-08

    The anode ablation rate is investigated as a function of anode diameter for a carbon nanotube arc plasma. It is found that anomalously high ablation occurs for small anode diameters. This result is explained by the formation of a positive anode sheath. The increased ablation rate due to this positive anode sheath could imply greater production rate for carbon nanotubes.

  15. Sheath structure transition controlled by secondary electron emission

    NASA Astrophysics Data System (ADS)

    Schweigert, I. V.; Langendorf, S. J.; Walker, M. L. R.; Keidar, M.

    2015-04-01

    In particle-in-cell Monte Carlo collision (PIC MCC) simulations and in an experiment we study sheath formation over an emissive floating Al2O3 plate in a direct current discharge plasma at argon gas pressure 10-4 Torr. The discharge glow is maintained by the beam electrons emitted from a negatively biased hot cathode. We observe three types of sheaths near the floating emissive plate and the transition between them is driven by changing the negative bias. The Debye sheath appears at lower voltages, when secondary electron emission is negligible. With increasing applied voltage, secondary electron emission switches on and a first transition to a new sheath type, beam electron emission (BEE), takes place. For the first time we find this specific regime of sheath operation near the floating emissive surface. In this regime, the potential drop over the plate sheath is about four times larger than the temperature of plasma electrons. The virtual cathode appears near the emissive plate and its modification helps to maintain the BEE regime within some voltage range. Further increase of the applied voltage U initiates the second smooth transition to the plasma electron emission sheath regime and the ratio Δφs/Te tends to unity with increasing U. The oscillatory behavior of the emissive sheath is analyzed in PIC MCC simulations. A plasmoid of slow electrons is formed near the plate and transported to the bulk plasma periodically with a frequency of about 25 kHz.

  16. INCORPORATING FOREIGN SHEATH BLIGHT RESISTANCE GENES INTO US RICE GEMPLASM

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight disease, caused by the Rhizoctonia solani fungus, has been the most economically significant rice disease throughout Texas, Louisiana, and Arkansas since the early 1970s. While diseases such as blast and straighthead can also devastate yield, sheath blight disease occurs more consiste...

  17. Generalized Analytical Model for the Radio-Frequency Sheath

    NASA Astrophysics Data System (ADS)

    Czarnetzki, Uwe

    2014-10-01

    An analytical model for the planar radio frequency (RF) sheath in capacitive discharges is developed based on the applied RF voltage as the boundary condition. The model applies to all kind of waveforms for the applied RF voltage, includes both sheaths in a discharge of arbitrary symmetry, and allows for an arbitrary degree of ion collisionallity in the sheaths (charge-exchange collisions). Further, effects of the finite floating potential during sheath collapse are included. The model can even be extended to electronegative plasmas with low bulk conductivity. The individual sheath voltages, the self-bias, and the RF floating potentials are explicitly calculated by a voltage balance equation using a cubic-charge voltage relation for the sheaths. In particular, the RF-phase as a function of the sheath voltage is determined. This is an input for a single second order non-linear integro-differential equation which is governing the ion flow velocity in the sheath. Fast numerical integration is straight forward and in many cases approximate analytical solutions can be obtained. Based on the solution for the ion flow velocity, densities, electric fields, currents, and charge-voltage relations are calculated. Further, the Child-Langmuir laws for the collisionless as well as the highly collisional case are derived. Very good agreement between model and experiments is obtained.

  18. Quality of paper boards from arecanut leaf sheath.

    PubMed

    Raghupathy, R; Viswanathan, R; Devadas, C T

    2002-03-01

    A study was carried on utilizing arecanut leaf sheath for making paper boards. Paper boards were made with various combinations of arecanut leaf sheath with waste paper, 1:1, 1:2, 1:3, 3:1, 2:1, control (100% areca leaf sheath) and the qualities of these paper boards were tested as per the Bureau of Indian Standards (IS: 1060 (part-I)-1966). The paper boards made with more arecanut sheath materials had more resistance to water absorption. The addition of paper increased the substance weight of the paper boards. The 2:1 and 3:1 combinations of arecanut leaf sheath and waste paper had best tear strength, tensile strength, bursting strength and water resistance with minimum substance weight. PMID:11848383

  19. An Everting Ureteral Access Sheath: Concepts and In Vitro Testing

    NASA Astrophysics Data System (ADS)

    Lee, Keith L.; Stoller, Marshall L.

    2007-04-01

    Ureteral access sheaths have been a recent innovation in facilitating ureteral stone surgery. Once properly placed, access sheaths allow the movement of ureteroscopes and other instruments through the ureter with minimal injury to the urothelium. However, there are shortcomings of the current device designs. Initial sheath placement requires significant force, and shear stress can injure the ureter. In addition, inadvertent advancement of the outer sheath without the inner introducer stylet can tear and avulse the ureter. A novel eversion design incorporating a lubricous film provides marked improvement over current access sheaths. In bench top and animal models, the eversion shealths require less force during advancement, cause less injury to the urothelial tissue, and have a lower potential of introducing extraneous materials (e.g., microbes) into a simulated urinary tract. While, the everting design provides important advantages over traditional non-everting designs, further preclinical and clinical trials are required.

  20. Gas insulated transmission line having low inductance intercalated sheath

    DOEpatents

    Cookson, Alan H.

    1978-01-01

    A gas insulated transmission line including an outer sheath, an inner conductor disposed within the outer sheath, and an insulating gas between the inner conductor and the outer sheath. The outer sheath comprises an insulating tube having first and second ends, and having interior and exterior surfaces. A first electrically conducting foil is secured to the interior surface of the insulating tube, is spirally wound from one tube end to the second tube end, and has a plurality of overlapping turns. A second electrically conducting foil is secured to the exterior surface of the insulating tube, and is spirally wound in the opposite direction from the first electrically conducting foil. By winding the foils in opposite directions, the inductances within the intercalated sheath will cancel each other out.

  1. Similarities and distinctions of CIR and Sheath

    NASA Astrophysics Data System (ADS)

    Yermolaev, Yuri; Lodkina, Irina; Nikolaeva, Nadezhda; Yermolaev, Michael

    2016-04-01

    On the basis of OMNI data and our catalog of large scale solar wind (SW) streams during 1976-2000 [Yermolaev et al., 2009] we study the average temporal profiles for two types of compressed regions: CIR (corotating interaction region - compressed region before High Speed Stream (HSS)) and Sheath (compressed region before fast Interplanetary CMEs (ICMEs), including Magnetic Cloud (MC) and Ejecta). As have been shown by Nikolaeva et al, [2015], the efficiency of magnetic storm generation is ~50% higher for Sheath and CIR than for ICME (MC and Ejecta), i.e. reaction magnetosphere depends on type of driver. To take into account the different durations of SW types, we use the double superposed epoch analysis (DSEA) method: rescaling the duration of the interval for all types in such a manner that, respectively, beginning and end for all intervals of selected type coincide [Yermolaev et al., 2010; 2015]. Obtained data allows us to suggest that the formation of all types of compression regions has the same physical mechanism irrespective of piston (HSS or ICME) type and differences are connected with geometry and full jumps of speed in edges of compression regions. If making the natural assumption that the gradient of speed is directed approximately on normal to the piston, CIR has the largest angle between the gradient of speed and the direction of average SW speed, and ICME - the smallest angle. The work was supported by the Russian Foundation for Basic Research, projects 13-02-00158, 16-02-00125 and by Program of Presidium of the Russian Academy of Sciences. References: Nikolaeva, N. S. , Yu. I. Yermolaev, and I. G. Lodkina (2015), Modeling of the Corrected Dst* Index Temporal Profile on the Main Phase of the Magnetic Storms Generated by Different Types of Solar Wind, Cosmic Research, Vol. 53, No. 2, pp. 119-127. Yermolaev, Yu. I., N. S. Nikolaeva, I. G. Lodkina, and M. Yu. Yermolaev (2009), Catalog of Large-Scale Solar Wind Phenomena during 1976-2000, Cosmic Research

  2. Space charge sheath in plasma-neutral gas interaction

    NASA Astrophysics Data System (ADS)

    Venkataramani, N.; Mattoo, S. K.

    1986-04-01

    A space charge sheath is found to be formed whenever a high-velocity magnetized plasma stream penetrates a gas cloud. The sheath is always located at the head of the plasma stream, and its thickness is very small compared to the length of the plasma stream. Soon after the sheath is formed it quickly slows down to the Alfven critical velocity. The plasma behind the sheath continues to move at higher velocity until the whole plasma stream is retarded to the critical velocity. In the interaction at gas density of about 10 to the 19th/cu cm, the sheaths are observed to be accompanied by a single loop of current with current density of about 10,000 A/sq m. Maximum potential in the sheath ranges between 50 and 200 V. Presently available models for the sheath may explain the initiation of the sheath formation. Physical processes like heating of the electrons and ionization of the gas cloud which come into play at a later stage of the interaction are not included in these models. These processes considerably alter the potential structure in the sheath region. A schematic model of the observed sheath is presented. Experiments reveal a threshold value of the magnetic field for plasma retardation to occur. This seems to correspond to the threshold condition for excitation of the modified two-stream instability, which can lead to the electron heating. The observed currents are found sufficient to account for the plasma retardation at a gas density of about 10 to the 17th/cu m.

  3. Bladder outlet reconstruction: fate of the silicone sheath.

    PubMed

    Kropp, B P; Rink, R C; Adams, M C; Keating, M A; Mitchell, M E

    1993-08-01

    The placement of a 1.5 cm. wide silicone sheath around a newly constructed urethra/bladder neck to ensure maintenance of repair length and to facilitate future placement of a sphincter cuff was reported by our institution in 1985. We present our long-term followup and new recommendations for use of the silicone sheath. A total of 15 silicone sheaths was placed between March 1981 and July 1984. Of the sheaths 14 were placed at the time of urinary reconstruction around the Young-Dees-Leadbetter bladder neck repair and 1 was placed after erosion of an artificial urinary sphincter cuff. Of the 15 sheaths 10 have eroded into the urethra and 4 sheaths remain in situ. Another sheath was replaced 2 years after its original insertion with an artificial urinary sphincter cuff. Mean time to erosion was 48.2 months, with a range of 2 to 108 months. Long-term followup of 10 patients revealed that 4 ultimately required ligation of the bladder neck and construction of continent stoma after erosion, 1 is dry after placement of a bulbar artificial urinary sphincter, 2 remain dry after removal of the eroded sheath alone, 2 required bladder neck revision to achieve continence after erosion and the most recent patient remains diverted with a suprapubic tube. All 4 patients with sheaths still remaining are dry without evidence of erosion (mean duration 116 months). These long-term results using a silicone wrap around a newly constructed bladder neck reveal an unacceptably high rate of erosion. Therefore, we no longer recommend or support the use of the silicone sheath in the manner we have described for bladder neck reconstruction. PMID:8326628

  4. Identification of a Gene Essential for Sheathed Structure Formation in Sphaerotilus natans, a Filamentous Sheathed Bacterium

    PubMed Central

    Suzuki, Toshihiko; Kanagawa, Takahiro; Kamagata, Yoichi

    2002-01-01

    Sphaerotilus natans, a filamentous bacterium that causes bulking in activated sludge processes, can assume two distinct morphologies, depending on the substrate concentration for growth; in substrate-rich media it grows as single rod-shaped cells, whereas in substrate-limited media it grows as filaments. To identify genes responsible for sheath formation, we carried out transposon Tn5 mutagenesis. Of the approximately 20,000 mutants obtained, 7 did not form sheathed structures. Sequencing of the Tn5-flanking regions showed that five of the seven Tn5 insertions converged at the same open reading frame, designated sthA. The deduced amino acids encoded by sthA were found to be homologous to glycosyltransferase, which is known to be involved in linking sugars to lipid carriers during bacterial exopolysaccharide biosynthesis. Disruption of the gene of the wild-type strain by inserting a kanamycin resistance gene cassette also resulted in sheathless growth under either type of nutrient condition. These findings indicate that sthA is a crucial component responsible for sheath formation. PMID:11772646

  5. Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths

    PubMed Central

    Kunoh, Tatsuki; Hashimoto, Hideki; McFarlane, Ian R.; Hayashi, Naoaki; Suzuki, Tomoko; Taketa, Eisuke; Tamura, Katsunori; Takano, Mikio; El-Naggar, Mohamed Y.; Kunoh, Hitoshi; Takada, Jun

    2016-01-01

    Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths. PMID:27271677

  6. Abiotic Deposition of Fe Complexes onto Leptothrix Sheaths.

    PubMed

    Kunoh, Tatsuki; Hashimoto, Hideki; McFarlane, Ian R; Hayashi, Naoaki; Suzuki, Tomoko; Taketa, Eisuke; Tamura, Katsunori; Takano, Mikio; El-Naggar, Mohamed Y; Kunoh, Hitoshi; Takada, Jun

    2016-01-01

    Bacteria classified in species of the genus Leptothrix produce extracellular, microtubular, Fe-encrusted sheaths. The encrustation has been previously linked to bacterial Fe oxidases, which oxidize Fe(II) to Fe(III) and/or active groups of bacterial exopolymers within sheaths to attract and bind aqueous-phase inorganics. When L. cholodnii SP-6 cells were cultured in media amended with high Fe(II) concentrations, Fe(III) precipitates visibly formed immediately after addition of Fe(II) to the medium, suggesting prompt abiotic oxidation of Fe(II) to Fe(III). Intriguingly, these precipitates were deposited onto the sheath surface of bacterial cells as the population was actively growing. When Fe(III) was added to the medium, similar precipitates formed in the medium first and were abiotically deposited onto the sheath surfaces. The precipitates in the Fe(II) medium were composed of assemblies of globular, amorphous particles (ca. 50 nm diameter), while those in the Fe(III) medium were composed of large, aggregated particles (≥3 µm diameter) with a similar amorphous structure. These precipitates also adhered to cell-free sheaths. We thus concluded that direct abiotic deposition of Fe complexes onto the sheath surface occurs independently of cellular activity in liquid media containing Fe salts, although it remains unclear how this deposition is associated with the previously proposed mechanisms (oxidation enzyme- and/or active group of organic components-involved) of Fe encrustation of the Leptothrix sheaths. PMID:27271677

  7. Charge separation in a magnetized plasma-sheath-lens

    NASA Astrophysics Data System (ADS)

    Stamate, Eugen

    2009-10-01

    Most of plasma processing technologies are based on radical-assisted ion-induced surface-modification where ions accumulate energy in the sheath, and then strike the surface modifying its properties in a desirable way. Plasma-sheath-lens is a three-dimensional potential distribution of customized shape, formed by the space charge surrounding a biased electrode-insulator interface. The discrete and modal focusing effects have been reveled for this type of electrostatic structures formed in plasma [1] and several applications including sheath thickness evaluation, negative ion detection and extraction of positive or negative ion beams have been developed. A non-magnetized plasma-sheath-lens act as a kinetic energy separator, but it is not mass sensitive. However, a magnetized plasma-sheath-lens exhibits mass separation, so that ions of different mass will impact the electrode at different locations on the biased electrode surface. The mass spectrum can be measured as the radial distribution of the ion current density over the plasma-sheath-lens's electrode. Relevant fluid and particles simulations of the magnetized plasma-sheath-lens structures and ion trajectories within them are presented for different plasma parameters and magnetic filed configurations. Practical aspects linked to the development of a new type of mass spectrometers are also investigated.[0pt] [1] E. Stamate and H. Sugai, Phys. Rev. Lett. (2005) 94, 125004

  8. Nonextensive statistics and the sheath criterion in collisional plasmas

    SciTech Connect

    Hatami, M. M.

    2015-01-15

    The Bohm criterion in an electropositive plasma containing nonextensively distributed electrons and warm ions is investigated by using a steady state two-fluid model. Taking into account the ion-neutral collisions and finite temperature of ions, a modified Bohm criterion is derived which limits both maximum and minimum allowable velocity of ions at the sheath edge (u{sub 0i}). It is found that the degree of nonextensivity of electrons (q) and temperature of positive ions (T{sub i}) affect only the lower limit of the entrance velocity of ions into the sheath while the degree of ion collisionality (α) influences both lower and upper limits of the ion velocities at the sheath edge. In addition, depending on the value of q, it is shown that the minimum velocity of positive ions at the sheath edge can be greater or smaller than its Maxwellian counterpart. Moreover, it is shown that, depending on the values of α and T{sub i}, the positive ions with subsonic velocity may enter the sheath for either q > 1 or −1 < q < 1. Finally, as a practical application, the density distribution of charged particles in the sheath region is studied for different values of u{sub 0i}, and it is shown that monotonical reduction of the positive ion density distribution occurs only when the velocity of positive ions at the sheath edge lies between two above mentioned limits.

  9. The plasma drag and dust motion inside the magnetized sheath

    SciTech Connect

    Pandey, B. P.; Vladimirov, S. V.; Samarian, A.

    2011-05-15

    The motion of micron size dust inside the sheath in the presence of an oblique magnetic field is investigated by self-consistently calculating the charge and various forces acting on the dust. It is shown that the dust trajectory inside the sheath, which is like an Archimedean spiral swinging back and forth between the wall and the plasma-sheath boundary, depends only indirectly on the orientation of the magnetic field. When the Lorentz force is smaller than the collisional momentum exchange, the dust dynamics is insensitive to the obliqueness of the magnetic field. Only when the magnetic field is strong enough, the sheath structure and, thus, the dust dynamics are significantly affected by the field orientation. Balance between the plasma drag, sheath electrostatic field, and gravity plays an important role in determining how far the dust can travel inside the sheath. The dust equilibrium point shifts closer to the wall in the presence of gravity and plasma drag. However, in the absence of plasma drag, dust can sneak back into the plasma if acted only by gravity. The implication of our results to the usability of dust as a sheath probe is discussed.

  10. The Tubular Sheaths Encasing Methanosaeta thermophila Filaments Are Functional Amyloids.

    PubMed

    Dueholm, Morten S; Larsen, Poul; Finster, Kai; Stenvang, Marcel R; Christiansen, Gunna; Vad, Brian S; Bøggild, Andreas; Otzen, Daniel E; Nielsen, Per Halkjær

    2015-08-14

    Archaea are renowned for their ability to thrive in extreme environments, although they can be found in virtually all habitats. Their adaptive success is linked to their unique cell envelopes that are extremely resistant to chemical and thermal denaturation and that resist proteolysis by common proteases. Here we employ amyloid-specific conformation antibodies and biophysical techniques to show that the extracellular cell wall sheaths encasing the methanogenic archaea Methanosaeta thermophila PT are functional amyloids. Depolymerization of sheaths and subsequent MS/MS analyses revealed that the sheaths are composed of a single major sheath protein (MspA). The amyloidogenic nature of MspA was confirmed by in vitro amyloid formation of recombinant MspA under a wide range of environmental conditions. This is the first report of a functional amyloid from the archaeal domain of life. The amyloid nature explains the extreme resistance of the sheath, the elastic properties that allow diffusible substrates to penetrate through expandable hoop boundaries, and how the sheaths are able to split and elongate outside the cell. The archaeal sheath amyloids do not share homology with any of the currently known functional amyloids and clearly represent a new function of the amyloid protein fold. PMID:26109065

  11. Ion Dynamics Model for Collisionless Radio Frequency Sheaths

    NASA Technical Reports Server (NTRS)

    Bose, Deepak; Govindan, T.R.; Meyyappan, M.

    2000-01-01

    Full scale reactor model based on fluid equations is widely used to analyze high density plasma reactors. It is well known that the submillimeter scale sheath in front of a biased electrode supporting the wafer is difficult to resolve in numerical simulations, and the common practice is to use results for electric field from some form of analytical sheath model as boundary conditions for full scale reactor simulation. There are several sheath models in the literature ranging from Child's law to a recent unified sheath model [P. A. Miller and M. E. Riley, J. Appl. Phys. 82, 3689 (1997)l. In the present work, the cold ion fluid equations in the radio frequency sheath are solved numerically to show that the spatiotemporal variation of ion flux inside the sheath, commonly ignored in analytical models, is important in determining the electric field and ion energy at the electrode. Consequently, a semianalytical model that includes the spatiotemporal variation of ion flux is developed for use as boundary condition in reactor simulations. This semianalytical model is shown to yield results for sheath properties in close agreement with numerical solutions.

  12. Morphogenesis of the fibrous sheath in the marsupial spermatozoon

    PubMed Central

    Ricci, M; Breed, WG

    2005-01-01

    The spermatozoon fibrous sheath contains longitudinal columns and circumferential ribs. It surrounds the axoneme of the principal piece of the mammalian sperm tail, and may be important in sperm stability and motility. Here we describe its assembly during spermiogenesis in a marsupial, the brush-tail possum, and compare its structural organization with that of eutherian mammals, birds and reptiles. Transmission electron microscopy showed that possum fibrous sheath assembly is a multistep process extending in a distal-to-proximal direction along the axoneme from steps 4 to 14 of spermiogenesis. For the most part, assembly of the longitudinal columns occurs before that of the circumferential ribs. Immunohistochemical and immunogold labelling showed that fibrous sheath proteins are first present in the spermatid cytoplasm; at least some of the proteins of the sheath precursors differ from those in the mature fibrous sheath. That immunoreactivity develops after initiation of chromatin condensation suggests that fibrous sheath proteins, or their mRNAs, are stored within the spermatid cytoplasmic lobule prior to their assembly along the axoneme. These findings are similar to those in laboratory rats, and thus suggests that the mode of fibrous sheath assembly evolved in a common ancestor over 125 million years ago, prior to the divergence of marsupial and eutherian lineages. PMID:16050902

  13. Structural and Biochemical Analysis of the Sheath of Phormidium uncinatum

    PubMed Central

    Hoiczyk, Egbert

    1998-01-01

    The sheath of the filamentous, gliding cyanobacterium Phormidium uncinatum was studied by using light and electron microscopy. In thin sections and freeze fractures the sheath was found to be composed of helically arranged carbohydrate fibrils, 4 to 7 nm in diameter, which showed a substantial degree of crystallinity. As in all other examined motile cyanobacteria, the arrangement of the sheath fibrils correlates with the motion of the filaments during gliding motility; i.e., the fibrils formed a right-handed helix in clockwise-rotating species and a left-handed helix in counterclockwise-rotating species and were radially arranged in nonrotating cyanobacteria. Since sheaths could only be found in old immotile cultures, the arrangement seems to depend on the process of formation and attachment of sheath fibrils to the cell surface rather than on shear forces created by the locomotion of the filaments. As the sheath in P. uncinatum directly contacts the cell surface via the previously identified surface fibril forming glycoprotein oscillin (E. Hoiczyk and W. Baumeister, Mol. Microbiol. 26:699–708, 1997), it seems reasonable that similar surface glycoproteins act as platforms for the assembly and attachment of the sheaths in cyanobacteria. In P. uncinatum the sheath makes up approximately 21% of the total dry weight of old cultures and consists only of neutral sugars. Staining reactions and X-ray diffraction analysis suggested that the fibrillar component is a homoglucan that is very similar but not identical to cellulose which is cross-linked by the other detected monosaccharides. Both the chemical composition and the rigid highly ordered structure clearly distinguish the sheaths from the slime secreted by the filaments during gliding motility. PMID:9683490

  14. Absence of Debye Sheaths Due to Secondary Electron Emission

    SciTech Connect

    M.D. Campanell, A. Khrabrov and I. D. Kaganovich

    2012-05-11

    A bounded plasma where the hot electrons impacting the walls produce more than one secondary on average is studied via particle-in-cell simulation. It is found that no classical Debye sheath or space-charge limited sheath exists. Ions are not drawn to the walls and electrons are not repelled. Hence the unconfined plasma electrons travel unobstructed to the walls, causing extreme particle and energy fluxes. Each wall has a positive charge, forming a small potential barrier or "inverse sheath" that pulls some secondaries back to the wall to maintain the zero current condition.

  15. Spontaneous rectus sheath hematoma in a patient treated with apixaban

    PubMed Central

    Aktas, Halil; Inci, Sinan; Dogan, Pinar; Izgu, Ibrahim

    2016-01-01

    Summary Apixaban, a non-vitamin K antagonist oral anticoagulants, is a Factor Xa inhibitor that is prescribed for the treatment of non valvular atrial fibrillation. Rectus sheath hematoma is a rare but significant complication of oral anticoagulant treatment. The important causes of rectus sheath hematoma include treatment with anticoagulants, hematologic diseases, trauma, intense physical activity, coughing, sneezing and pregnancy. In this report, we describe case of a 71-year-old woman undergoing apixaban treatment for non valvular atrial fibrillation who presented with spontaneous rectus sheath hematoma. PMID:26989650

  16. Measurement of sheath thickness at a floating potential

    SciTech Connect

    Han, Hyung-Sik; Lee, Hyo-Chang; Oh, Se-Jin; Chung, Chin-Wook

    2014-02-15

    In a cylindrical Langmuir probe measurement, ion current is collected from the surface of the sheath surrounded at probe tip, not at the surface of the probe tip. By using this, the sheath thickness can be obtained, if we know some unknown parameters, such as ion current, plasma density, and electron temperature. In this paper, we present a method to measure sheath thickness by using a wave cutoff method and a floating harmonic method. The measured result is in a good agreement with Allen-Boyd-Reynolds theory.

  17. Giant Cell Tumor of the Peroneus Brevis Tendon Sheath

    PubMed Central

    Ch, Li; TH, Lui

    2015-01-01

    Introduction: Giant cell tumor of the tendon sheath is most commonly found in the flexor aspect of hand and wrist and is rare in the foot and ankle. Case report: A 49-year-old lady noticed a right lateral foot mass for 10 years. Magnetic resonance imaging suggested that the mass is originated from the peroneal tendons. The mass was excised and intra-operative findings showed that the tumor came from the peroneus brevis tendon sheath. Histological study confirmed the diagnosis of giant cell tumor. Conclusion: Giant cell tumor, although rare, should be one of the differential diagnoses of tendon sheath tumor of the foot and ankle. PMID:27299104

  18. Analytical model for the radio-frequency sheath

    NASA Astrophysics Data System (ADS)

    Czarnetzki, Uwe

    2013-12-01

    A simple analytical model for the planar radio-frequency (rf) sheath in capacitive discharges is developed that is based on the assumptions of a step profile for the electron front, charge exchange collisions with constant cross sections, negligible ionization within the sheath, and negligible ion dynamics. The continuity, momentum conservation, and Poisson equations are combined in a single integro-differential equation for the square of the ion drift velocity, the so called sheath equation. Starting from the kinetic Boltzmann equation, special attention is paid to the derivation and the validity of the approximate fluid equation for momentum balance. The integrals in the sheath equation appear in the screening function which considers the relative contribution of the temporal mean of the electron density to the space charge in the sheath. It is shown that the screening function is quite insensitive to variations of the effective sheath parameters. The two parameters defining the solution are the ratios of the maximum sheath extension to the ion mean free path and the Debye length, respectively. A simple general analytic expression for the screening function is introduced. By means of this expression approximate analytical solutions are obtained for the collisionless as well as the highly collisional case that compare well with the exact numerical solution. A simple transition formula allows application to all degrees of collisionality. In addition, the solutions are used to calculate all static and dynamic quantities of the sheath, e.g., the ion density, fields, and currents. Further, the rf Child-Langmuir laws for the collisionless as well as the collisional case are derived. An essential part of the model is the a priori knowledge of the wave form of the sheath voltage. This wave form is derived on the basis of a cubic charge-voltage relation for individual sheaths, considering both sheaths and the self-consistent self-bias in a discharge with arbitrary

  19. Spontaneous rectus sheath hematoma in a patient treated with apixaban.

    PubMed

    Aktas, Halil; Inci, Sinan; Dogan, Pinar; Izgu, Ibrahim

    2016-02-01

    Apixaban, a non-vitamin K antagonist oral anticoagulants, is a Factor Xa inhibitor that is prescribed for the treatment of non valvular atrial fibrillation. Rectus sheath hematoma is a rare but significant complication of oral anticoagulant treatment. The important causes of rectus sheath hematoma include treatment with anticoagulants, hematologic diseases, trauma, intense physical activity, coughing, sneezing and pregnancy. In this report, we describe case of a 71-year-old woman undergoing apixaban treatment for non valvular atrial fibrillation who presented with spontaneous rectus sheath hematoma. PMID:26989650

  20. Morphological analysis of the sheathed flagellum of Brucella melitensis

    PubMed Central

    2010-01-01

    Background It was recently shown that B. melitensis is flagellated. However, the flagellar structure remains poorly described. Findings We analyzed the structure of the polar sheathed flagellum of B. melitensis by TEM analysis and demonstrated that the Ryu staining is a good method to quickly visualize the flagellum by optical microscopy. The TEM analysis demonstrated that an extension of the outer membrane surrounds a filament ending by a club-like structure. The ΔftcR, ΔfliF, ΔflgE and ΔfliC flagellar mutants still produce an empty sheath. Conclusions Our results demonstrate that the flagellum of B. melitensis has the characteristics of the sheathed flagella. Our results also suggest that the flagellar sheath production is not directly linked to the flagellar structure assembly and is not regulated by the FtcR master regulator. PMID:21143933

  1. Ureteric access sheath aided insertion of resonance metal ureteric stent

    PubMed Central

    Winter, Matthew; Strahan, Stephen; Wines, Michael

    2014-01-01

    Ureteral obstruction caused by malignancy is a challenging and often complicated problem for urologists. We present a novel technique of ureteric access sheath aided insertion of a Resonance metal ureteric stent in the setting of a difficult obstruction. PMID:24879725

  2. Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

    SciTech Connect

    Grin, A.; Lstiburek, J.

    2014-09-01

    The goal of this research is to provide durable and long-term water management solutions using exterior insulating sheathing as part of the water management system. It is possible to tape or seal the joints in insulating sheathing to create a drainage plane and even an air control layer. There exists the material durability component of the tape as well as the system durability component being the taped insulating sheathing as the drainage plane. This measure guideline provides best practice and product recommendations from the interviewed contractors and homebuilders who collectively have a vast amount of experience. Three significant issues were discussed with the group, which are required to make taped insulating sheathing a simple, long-term, and durable drainage plane: horizontal joints should be limited or eliminated wherever possible; where a horizontal joint exists use superior materials; and frequent installation inspection and regular trade training are required to maintain proper installation.

  3. A radio-frequency sheath model for complex waveforms

    SciTech Connect

    Turner, M. M.; Chabert, P.

    2014-04-21

    Plasma sheaths driven by radio-frequency voltages occur in contexts ranging from plasma processing to magnetically confined fusion experiments. An analytical understanding of such sheaths is therefore important, both intrinsically and as an element in more elaborate theoretical structures. Radio-frequency sheaths are commonly excited by highly anharmonic waveforms, but no analytical model exists for this general case. We present a mathematically simple sheath model that is in good agreement with earlier models for single frequency excitation, yet can be solved for arbitrary excitation waveforms. As examples, we discuss dual-frequency and pulse-like waveforms. The model employs the ansatz that the time-averaged electron density is a constant fraction of the ion density. In the cases we discuss, the error introduced by this approximation is small, and in general it can be quantified through an internal consistency condition of the model. This simple and accurate model is likely to have wide application.

  4. Plasma sheath multipath analysis and its effect on GNSS navigation

    NASA Astrophysics Data System (ADS)

    Du, Yongxing; Xi, Xiaoli; Song, Zhongguo; Liu, Jiangfan

    2015-11-01

    When hypersonic vehicle reenters the Earth's atmosphere, the plasma sheath will be generated by its collision with ambient air that would affect global navigation satellite system (GNSS). In order to understand such effects, the transmission coefficient of the plasma sheath has been investigated using the numerical method before. But this is found to be insufficient, for besides the attenuation on the signal energy, the multipath effect between the plasma sheath and the vehicle surface is also a serious factor, which may result in errors in pseudorange measurement and carrier phase measurement of GNSS receiver and finally affect the positioning accuracy. The multipath of the plasma sheath is analyzed by finite-difference time-domain method combined with further signal processing, and a simulation platform is established to verify this effects on positioning performance. Simulation results indicate the degradation of positioning performance when these multipath signals were present, causing position error with several meters to tens of meters.

  5. Porous protective solid phase micro-extractor sheath

    DOEpatents

    Andresen, Brian D.; Randich, Erik

    2005-03-29

    A porous protective sheath for active extraction media used in solid phase microextraction (SPME). The sheath permits exposure of the media to the environment without the necessity of extending a fragile coated fiber from a protective tube or needle. Subsequently, the sheath can pierce and seal with GC-MS septums, allowing direct injection of samples into inlet ports of analytical equipment. Use of the porous protective sheath, within which the active extraction media is contained, mitigates the problems of: 1) fiber breakage while the fiber is extended during sampling, 2) active media coating loss caused by physical contact of the bare fiber with the sampling environment; and 3) coating slough-off during fiber extension and retraction operations caused by rubbing action between the fiber and protective needle or tube.

  6. USP6 genetic rearrangements in cellular fibroma of tendon sheath.

    PubMed

    Carter, Jodi M; Wang, Xiaoke; Dong, Jie; Westendorf, Jennifer; Chou, Margaret M; Oliveira, Andre M

    2016-08-01

    Fibroma of tendon sheath is a benign (myo)fibroblastic neoplasm of the tenosynovial soft tissues, typically affecting the distal extremities. It is classically described as a paucicellular, densely collagenized tumor; however, cellular variants have been described. A subset of cellular fibromas of tendon sheath shares similar histological features with nodular fasciitis. As nodular fasciitis very frequently harbors rearrangement of ubiquitin-specific peptidase 6 (USP6), we hypothesized that cellular fibromas of tendon sheath with nodular fasciitis-like features may also contain USP6 rearrangements. Cases of fibroma of tendon sheath (n=19), including cellular (n=9) and classic (n=10) variants, were evaluated for USP6 rearrangement by fluorescence in situ hybridization studies. A subset of cases was tested for MYH9 rearrangements and MYH9-USP6 and CDH11-USP6 fusion products. Classic fibroma of tendon sheath occurred in 5 males and 5 females (median age 67 years, range 23-77 years) as soft tissue masses of the hand (n=4), finger (n=3), forearm (n=1) and foot (n=2). Cellular fibroma of tendon sheath occurred in 5 males and 4 females in a younger age group (median age 32 years, range 12-46 years) as small soft tissue masses of the finger (n=5), hand (n=3) and wrist (n=1). USP6 rearrangements were detected in 6/9 cellular fibromas of tendon sheath. Among cellular fibromas of tendon sheath with USP6 rearrangements, no MYH9 rearrangements were detected. By RT-PCR, neither the MYH9-USP6 or the CDH11-USP6 fusion products were detected in any case. Neither USP6 nor MYH9 rearrangement were detected in any classic fibroma of tendon sheath. We report for the first time the presence of USP6 rearrangements in a subset of cellular fibroma of tendon sheath. Based on the similar morphological and molecular genetic features, we suspect that a subset of cellular fibromas of tendon sheath are under-recognized examples of tenosynovial nodular fasciitis, driven by alternate USP6 fusion

  7. Scale invariant sheath folds in salt, sediments and shear zones

    NASA Astrophysics Data System (ADS)

    Alsop, G. I.; Holdsworth, R. E.; McCaffrey, K. J. W.

    2007-10-01

    Sheath folds are developed in a broad spectrum of geological environments in which material flow occurs, including gravity-driven surficial deformation in ignimbrites, unconsolidated sediments and salt, together with deeper level ductile shear zones in metamorphic rocks. This study represents the first geometric comparison of sheath folds in these different settings across a wide range of scales. Elliptical closures defining eye-folds represent ( y- z) cross sections through highly-curvilinear sheath folds. Our analysis of the published literature, coupled with field observations, reveals remarkably similar ellipticities ( R yz) for sheath folds in metamorphic shear zones ( R yz 4.23), salt ( R yz 4.29), sediment slumps ( R yz 4.34), glaciotectonites ( R yz 4.48), and ignimbrites ( R yz 4.34). Nested eye-folds across this range of materials ( N = 1800) reveal distinct and consistent differences in ellipticity from the outer- ( R yz) to the inner-most ( R y' z' ) elliptical "rings" of individual sheath folds. The variation in ratios from outer to inner rings ( R' = R yz/ R y' z' ) in gravity-driven surficial flows typically displays a relative increase in ellipticity to define cats-eye-folds ( R' < 1) similar to those observed during simple and general shear in metamorphic rocks. We show that sheath folds develop across a range of scales within these different environments, and display elliptical ratios ( R yz) that are remarkably constant ( R2 > 0.99) across 9 orders of magnitude (sheath y axes range from ˜0.1 mm to >75 km). Our findings lead us to conclude that the geometric properties of sheath folds are scale invariant and primarily controlled by the type and amount of strain, with R' also reflecting the rheological significance of layering associated with original buckle fold mechanisms. The scaling pattern of sheath folds reflects the length scales of the precursor buckle folds (and width of deformation zones) across a broad range of materials and

  8. Use of ureteral access sheaths in ureteroscopy.

    PubMed

    Kaplan, Adam G; Lipkin, Michael E; Scales, Charles D; Preminger, Glenn M

    2016-03-01

    The ureteral access sheath (UAS) facilitates the use of flexible ureteroscopy, enabling improved minimally invasive management of complex upper urinary tract diseases. The UAS, which comes in a variety of diameters and lengths, is passed in a retrograde fashion, aided by a hydrophilic coating and other features designed to confer smooth passage into the ureter with sufficient resistance to kinking and buckling. Use of a UAS has the advantage of enabling repeated passage of the ureteroscope while minimizing damage to the ureter, thus improving the flow of irrigation fluid and visualization within the urethra with reductions in operative times, which improves both the effectiveness of the surgery and reduces the costs. Placement of the UAS carries an increased risk of ureteral wall ischaemia and injury to the mucosal or muscular layers of the ureter, and a theoretically increased risk of ureteral strictures. A ureteral stent is typically placed after ureteroscopy with a UAS. Endourologists have found several additional practical uses of a UAS, such as the percutaneous treatment of patients with ureteral stones, and solutions to other endourological challenges. PMID:26597613

  9. Solitary fibrous tumor surrounding the carotid sheath.

    PubMed

    Gómez-Oliveira, Guillermo; Alvarez-Flores, Modesto; Arribas-García, Ignacio; Martínez-Gimeno, Carlos

    2010-03-01

    Solitary fibrous tumors (SFTs) are rare spindle cell neoplasms that are mostly found arising from the pleura. Although SFTs recently have been reported in other regions, they are rare in the head and neck and have often been misdiagnosed due to their rarity. SFTs are benign in most cases. Clinically, SFTs usually manifest as well-circumscribed, slow-growing, smooth and painless masses. Symptoms are often minimal, although they may include sore throat, difficulty in swallowing, change of voice or trismus. CT-Scan and MRI are the most sensitive imaging procedures used. The treatment of choice is complete surgical excision of the lesion. Because recurrences have been noted up to 30 years after surgery, long-term follow up is mandatory. In this article, we present a case of a Solitary Fibrous Tumor arising in the parapharyngeal space in a 20-year-old man, involving the carotid sheath, treated by surgical excision with no recurrence after 1 year. The clinical presentation, surgical management and pathological findings are described. PMID:19767703

  10. Giant Cell Tumor of Tendon Sheath

    PubMed Central

    Briët, Jan Paul; Becker, Stéphanie JE; Oosterhoff, Thijs CH; Ring, David

    2015-01-01

    Background: Giant cell tumor of tendon sheath (GCTTS) is often thought of as a volar finger mass. We hypothesized that GCTTS are equally common on the dorsal and volar aspects of the hand. In addition, we hypothesized that there are no factors associated with the location (volar versus dorsal) and largest measured dimension of a GCTTS. Methods: A total of 126 patients with a pathological diagnosis of a GCTTS of the hand or finger were reviewed. Basic demographic and GCTTS specific information was obtained. Bivariable analyses were used to assess predicting factors for location (volar or dorsal side) and largest measured diameter of a GCTTS. Results: Seventy-two tumors (57%) were on the volar side of the hand, 47 (37%) were dorsal, 6 (4.8%) were both dorsal and volar, and one was midaxial (0.79%). The most common site of a GCTTS was the index finger (30%). There were no factors significantly associated with the location (volar or dorsal, n=119) of the GCTTS. There were also no factors significantly associated with a larger diameter of a GCTTS. Conclusions: A GCTTS was more frequently seen on the volar aspect of the hand. No significant factors associated with the location or an increased size of a GCTTS were found in this study. PMID:25692164

  11. LH Wave Coupling And ICRF Sheaths At JET

    SciTech Connect

    Kirov, K. K.; Baranov, Yu.; Erents, K.; Jacquet, P.; Mailloux, J.; Mayoral, M.-L.; Stamp, M.; Petrzilka, V.

    2007-09-28

    Lower Hybrid (LH) wave coupling deteriorates when the system is pulsed with Ion Cyclotron Range of Frequencies (ICRF) antennas magnetically connected to the launcher. This has been attributed to the density modifications by the RF sheaths. Reflection Coefficients (RCs) dependencies are investigated and shown consistent with the sheath physics. Gas puffing near the launcher has been used to improve the coupling. Results from a statistical analysis of a particular set of data are summarised.

  12. On the Formation of Particle Sheaths in Columnar Vortices.

    NASA Astrophysics Data System (ADS)

    Snow, John T.

    1984-08-01

    Geophysical columnar vortices such as tornadoes, waterspouts and dust devils are frequently observed to have one or more cylindrical sheaths of dust concentric with the axis of symmetry. The mechanisms by which such sheaths form have previously been investigated by assuming a balance between inward drag force (due to inward radial motion of the fluid) and outward centrifugal form (due to rotation of the particles around the vortex). However, the strong radial inflow required to establish this balance is confined to the surface inflow layer. In the upper two thirds of the vortex core, where the sheaths are most frequently observed, the radial component of fluid motion is very weak and may be outward. In this study, an alternative approach is presented wherein the drag forces arising from radial motion of the fluid are assumed negligible. The particles are thus continuously centrifuged out of the core. It is shown for four representative profiles of the tangential velocity component of the fluid that a particle sheath will form. The time required for its formation, the location of the sheath, and its evolution in time are in agreement with the available field evidence. Also, a two-celled vortex flow field is shown to produce a two-sheath structure. However, the inner sheath is a transient feature, so it is argued that the observed patterns of multiple concentric sheaths are probably due to the combined effects of the lifting of puffs of particles aloft by the vertical motion field while at the same time the particles are centrifuged out of the core.

  13. Volar wrist ganglion excision through the flexor carpi radialis sheath.

    PubMed

    Sawyer, Gregory A; DaSilva, Manuel F; Akelman, Edward

    2012-09-01

    Volar wrist ganglions are much less frequent than their dorsal counterparts but provide much more surgical trepidation due to their proximity to the radial artery. With the majority arising from the radiocarpal joint, we have found that entering the flexor carpi radialis sheath and accessing the ganglion through the floor of the sheath allows for a relatively safe excision of these benign hand tumors. PMID:22913995

  14. Sheath ionization model of beam emissions from large spacecraft

    NASA Technical Reports Server (NTRS)

    Lai, S. T.; Cohen, H. A.; Bhavnani, K. H.; Tautz, M. E.

    1985-01-01

    An analytical model of the charging of a spacecraft emitting electron and ion beams has been applied to the case of large spacecraft. In this model, ionization occurs in the sheath due to the return current. Charge neutralization of spherical space charge flow is examined by solving analytical equations numerically. Parametric studies of potential large spacecraft are performed. As in the case of small spacecraft, the ions created in the sheath by the returning current play a large role in determining spacecraft potential.

  15. Miniature sheathed thermocouples for turbine blade temperature measurement

    NASA Technical Reports Server (NTRS)

    Holanda, R.; Glawe, G. E.; Krause, L. N.

    1974-01-01

    An investigation was made of sheathed thermocouples for turbine blade temperature measurements. Tests were performed on the Chromel-Alumel sheathed thermocouples with both two-wire and single-wire configurations. Sheath diameters ranged from 0.25 to 0.76 mm, and temperatures ranged from 1080 to 1250 K. Both steady-state and thermal cycling tests were performed for times up to 450 hr. Special-order and commercial-grade thermocouples were tested. The tests showed that special-order single-wire sheathed thermocouples can be obtained that are reliable and accurate with diameters as small as 0.25 mm. However, all samples of 0.25-mm-diameter sheathed commercial-grade two-wire and single-wire thermocouples that were tested showed unacceptable drift rates for long-duration engine testing programs. The drift rates were about 1 percent in 10 hr. A thermocouple drift test is recommended in addition to the normal acceptance tests in order to select reliable miniature sheathed thermocouples for turbine blade applications.

  16. Photoelectric sheath formation around small spherical objects in space

    SciTech Connect

    Misra, Shikha Sodha, M. S.; Mishra, S. K.

    2015-04-15

    The formation of a photoelectron sheath around positively charged small (∼cm) spherical objects roaming in near earth space due to the solar radiation (with continuous spectrum) and the solar wind plasma has been investigated. The sheath structure has been derived, taking into account anisotropic photoelectron flux with the Poisson equation, spherical geometry of the object, and half Fermi Dirac distribution of photoelectron velocities. Two cases, viz., when the object is illuminated by (i) isotropic or (ii) unidirectional (parallel beam) radiation, have been analyzed. The analysis predicts a spherically symmetric sheath in case of isotropic illumination, while a symmetry in sheath about a θ=π/4 is seen in case of parallel beam illumination; θ is the angle of incidence which is the angle made by the normal to a surface element with the direction of incidence of solar radiation. The radial and angular profiles of the electric potential and electron density in the photoelectron sheath have been evaluated and illustrated graphically; the dependence of the sheath structure on the solar wind plasma parameters, material properties of the spherical object, and its size have been discussed.

  17. Why ions enter the sheath entrance at supersonic speed?

    NASA Astrophysics Data System (ADS)

    Tang, Xianzhu; Guo, Zehua

    2015-11-01

    In a boundary plasma of a fusion device, the sheath Knudsen number, which is defined as the ratio of the plasma mean-free-path and the plasma Debye length, is much greater than unity, so one anticipates a collisionless sheath, even though the overall boundary plasma in the scrape-off layer is collisional. This is supposed to be the regime for which the Bohm criteria for the ion entry flow at the sheath entrance, v >=cs with cs the sound speed, is usually satisfied at the equal sign. But numerical simulations using first-principles particle-in-cell codes tend to report a supersonic flow. Here we revisit the two-scale and transition layer analysis of the sheath-presheath transition, in tandem with the conventional Bohm criteria analysis, to understand why and how the supersonic sheath entry flow is established at the sheath entrance, which is a few Debye length away from the wall, and its impact on plasma particle and power load at the wall. Works upported by DOE OFES. Work supported by DOE OFES.

  18. Type VI secretion system sheaths as nanoparticles for antigen display

    PubMed Central

    Del Tordello, Elena; Danilchanka, Olga; McCluskey, Andrew J.; Mekalanos, John J.

    2016-01-01

    The bacterial type 6 secretion system (T6SS) is a dynamic apparatus that translocates proteins between cells by a mechanism analogous to phage tail contraction. T6SS sheaths are cytoplasmic tubular structures composed of stable VipA-VipB (named for ClpV-interacting protein A and B) heterodimers. Here, the structure of the VipA/B sheath was exploited to generate immunogenic multivalent particles for vaccine delivery. Sheaths composed of VipB and VipA fused to an antigen of interest were purified from Vibrio cholerae or Escherichia coli and used for immunization. Sheaths displaying heterologous antigens generated better immune responses against the antigen and different IgG subclasses compared with soluble antigen alone. Moreover, antigen-specific antibodies raised against sheaths presenting Neisseria meningitidis factor H binding protein (fHbp) antigen were functional in a serum bactericidal assay. Our results demonstrate that multivalent nanoparticles based on the T6SS sheath represent a versatile scaffold for vaccine applications. PMID:26929342

  19. Effects of emitted electron temperature on the plasma sheath

    SciTech Connect

    Sheehan, J. P.; Kaganovich, I. D.; Wang, H.; Raitses, Y.; Sydorenko, D.; Hershkowitz, N.

    2014-06-15

    It has long been known that electron emission from a surface significantly affects the sheath surrounding that surface. Typical fluid theory of a planar sheath with emitted electrons assumes that the plasma electrons follow the Boltzmann relation and the emitted electrons are emitted with zero energy and predicts a potential drop of 1.03T{sub e}/e across the sheath in the floating condition. By considering the modified velocity distribution function caused by plasma electrons lost to the wall and the half-Maxwellian distribution of the emitted electrons, it is shown that ratio of plasma electron temperature to emitted electron temperature significantly affects the sheath potential when the plasma electron temperature is within an order of magnitude of the emitted electron temperature. When the plasma electron temperature equals the emitted electron temperature the emissive sheath potential goes to zero. One dimensional particle-in-cell simulations corroborate the predictions made by this theory. The effects of the addition of a monoenergetic electron beam to the Maxwellian plasma electrons were explored, showing that the emissive sheath potential is close to the beam energy only when the emitted electron flux is less than the beam flux.

  20. Photoelectric sheath formation around small spherical objects in space

    NASA Astrophysics Data System (ADS)

    Misra, Shikha; Mishra, S. K.; Sodha, M. S.

    2015-04-01

    The formation of a photoelectron sheath around positively charged small (˜cm) spherical objects roaming in near earth space due to the solar radiation (with continuous spectrum) and the solar wind plasma has been investigated. The sheath structure has been derived, taking into account anisotropic photoelectron flux with the Poisson equation, spherical geometry of the object, and half Fermi Dirac distribution of photoelectron velocities. Two cases, viz., when the object is illuminated by (i) isotropic or (ii) unidirectional (parallel beam) radiation, have been analyzed. The analysis predicts a spherically symmetric sheath in case of isotropic illumination, while a symmetry in sheath about a θ = π / 4 is seen in case of parallel beam illumination; θ is the angle of incidence which is the angle made by the normal to a surface element with the direction of incidence of solar radiation. The radial and angular profiles of the electric potential and electron density in the photoelectron sheath have been evaluated and illustrated graphically; the dependence of the sheath structure on the solar wind plasma parameters, material properties of the spherical object, and its size have been discussed.

  1. The sheath effect on the floating harmonic method

    SciTech Connect

    Lee, Jaewon; Kim, Kyung-Hyun; Chung, Chin-Wook

    2015-12-15

    The floating harmonic method biases sinusoidal voltage to a probe sheath, and as its response, harmonic currents can be obtained. These currents can be used to determine the plasma parameters. However, different shapes of probes have different shapes of sheaths that can affect the diagnostic results. However, no research has been done on the sheath effect on the floating harmonic method. Therefore, we investigate the effect of the sheath during floating harmonic diagnostics by comparing cylindrical and planar probes. While the sinusoidal voltages were applied to a probe, because the sheath oscillated, the time variant ion current and their harmonic currents were added to the electron harmonic currents. In the floating harmonic method, the harmonic currents are composed of only the electron harmonic currents. Therefore, the ion harmonic currents affect the diagnostic results. In particular, the electron temperature obtained by the small probe tip was higher than that of the large probe tip. This effect was exacerbated when the ratio of the probe tip radius to the sheath length was smaller.

  2. An Analytical Model for the Radio-Frequency Sheath

    NASA Astrophysics Data System (ADS)

    Czarnetzki, Uwe

    2013-09-01

    An analytical model for the planar radio frequency (RF) sheath in capacitive discharges is developed based on the applied RF voltage as the boundary condition. In a first step, the individual sheath voltages and the self-bias are calculated using a cubic-charge voltage relation. In the second step, a single integro-differential equation is derived to describe the ion flow velocity in the sheath under all conditions of collisionality. Central to the model is the screening function that describes the screening of the ion density by the mean electron density in the sheath. Numerical integration of the sheath equation is straight forward. However, for the collisionless as well as the collisional case explicit, simple, and precise analytical approximations can be found. Drift velocities, densities, fields, currents, and charge-voltage relations are calculated. Further, the Child-Langmuir laws for both cases of collisonality are derived. These solutions are in very good agreement with experimental data from the literature based on laser electric field measurements, the Brinkmann sheath model, and PIC simulations. The technique works well also for other waveforms, e.g. the electrical asymmetry effect or tailored pulse waveforms.

  3. A theoretical model of sheath fold morphology in simple shear

    NASA Astrophysics Data System (ADS)

    Reber, Jacqueline E.; Dabrowski, Marcin; Galland, Olivier; Schmid, Daniel W.

    2013-04-01

    Sheath folds are highly non-cylindrical structures often associated with shear zones. The geometry of sheath folds, especially cross-sections perpendicular to the stretching direction that display eye-patterns, have been used in the field to deduce kinematic information such as shear sense and bulk strain type. However, how sheath folds form and how they evolve with increasing strain is still a matter of debate. We investigate the formation of sheath folds around a weak inclusion acting as a slip surface in simple shear by means of an analytical model. We systematically vary the slip surface orientation and shape and evaluate the impact on the evolving eye-pattern. In addition we compare our results to existing classifications. Based on field observations it has been suggested that the shear sense of a shear zone can be determined by knowing the position of the center of an eye-pattern and the closing direction of the corresponding sheath fold. In our modeled sheath folds we can observe for a given strain that the center of the eye-structure is subject to change in height with respect to the upper edge of the outermost closed contour for different cross-sections perpendicular to the shear direction. This results in a large variability in layer thickness, questioning the usefulness of sheath folds as shear sense indicators. The location of the center of the eye structure, however, is largely invariant to the initial configurations of the slip surface as well as to strain. It has been suggested that the ratio of the aspect ratio of the innermost and outermost closed contour in eye-patterns could be linked to the bulk strain type based on filed observations. We apply this classification to our modeled sheath folds and we observe that the values of the aspect ratios of the closed contours within the eye-pattern are dependent on the strain and the cross-section location. The ratio (R') of the aspect ratios of the outermost closed contour (Ryz) and the innermost closed

  4. Ion Velocimetry In Magnetized DC Sheaths

    NASA Astrophysics Data System (ADS)

    Young, Christopher; Lucca Fabris, Andrea; Cappelli, Mark

    2013-09-01

    Particle dynamics near the magnetic cusps in cusped field plasma thrusters are still not well understood; characterizing the ion velocity distribution functions in these regions can help thruster designs maximize electron trapping and minimize erosion of the channel wall. To that end, a robust argon ion velocity sensor is developed using a three-level laser-induced fluorescence (LIF) technique. The 3d4F7 / 2 --> 4p4D5/ 2 0 ArII transition at 668.61 nm is pumped with a 25 mW tunable external cavity diode laser, and fluorescence down to the 4s4P3 / 2 state at 442.72 nm is collected with phase-sensitive detection. The Doppler shift in the acquired signal peak, compared to a stationary reference, gives the ion velocity component parallel to the exciting laser. We demonstrate this LIF scheme by obtaining the argon ion velocity profile through a magnetized DC sheath. The LIF measurement is used to validate a new optogalvanic velocimetry technique in which two lasers (chopped at different frequencies) intersect one another at 90° in the measurement volume. Using a lock-in amplifier, changes observed in the DC discharge current at the sum and difference of the two chopping frequencies may be related back to the mean ion velocity at that point. The authors acknowledge support from the Air Force Office of Scientific Research (AFOSR). CY acknowledges support from the DOE NNSA Stewardship Science Graduate Fellowship under contract DE-FC52-08NA28752.

  5. Collector and source sheaths of a finite ion temperature plasma

    SciTech Connect

    Schwager, L.A.; Birdsall, C.K. )

    1990-05-01

    The region between a Maxwellian plasma source and an absorbing surface is described theoretically with a static, kinetic plasma--sheath model and modeled numerically with a dynamic, electrostatic particle simulation. In the kinetic theory, Poisson's equation and Vlasov equations govern the non-Maxwellian velocity distribution of the ions and electrons. The results in this paper for collector potential and plasma transport agree with the bounded model of Emmert {ital et} {ital al}. (Phys. Fluids {bold 23}, 803 (1980)). However, this approach differs from those using traditional Bohm sheath analysis by {plus minus}0.25 (in units of electron temperature) for potential drop through the collector sheath of a hydrogen plasma. In both the theory and simulation, the plasma source injects equal fluxes of ions and electrons with half-Maxwellian velocities and various mass and temperature ratios and is assumed to have a zero electric field. The potential change within a spatially distributed, full Maxwellian source region is represented with the source sheath potential drop that depends primarily on temperature ratio. This source sheath evolves over a few Debye lengths from the source to neutralize the injected plasma. The plasma flows to an electrically floating collector where the more familiar electron-repelling collector sheath appears. The collector potential {psi}{sub {ital C}} and source sheath potential drop {psi}{sub {ital P}} (in units of electron temperature) are evaluated as a function of mass and temperature ratio. The velocity moments of density, drift velocity, temperature, kinetic energy flux, and heat flux are also derived as a function of {psi}{sub {ital C}} and {psi}{sub {ital P}}. Comparisons with electrostatic particle simulations are shown for the ion/electron mass ratios of 40 and 100 and temperature ratios of 0.1, 1, and 10.

  6. On the usefulness of sheath folds as kinematic indicators

    NASA Astrophysics Data System (ADS)

    Reber, J. E.; Galland, O.; Dabrowski, M.; Schmid, D. W.; Cobbold, P. R.

    2012-04-01

    Sheath folds are cone-shaped structures that can be found in different rock types. They are mostly associated with shear zones. Even though they are three-dimensional structures they are most commonly recognized in nature in cross sections perpendicular to their stretching direction. These cross-sections exhibit so called eye-structures. The geometry of sheath folds has been used to deduce kinematic information such as strain, shear sense, and bulk strain type. However, how sheath folds form and how they evolve with increasing strain is still a matter of debate. We studied the development of sheath folds at the tip of a slip surface (weak inclusion) embedded in a layered matrix subjected to simple shear by means of analytical and experimental modeling. With this combined approach we tested the usefulness of sheath folds as indicators of strain, shear direction and bulk strain type. The analytical model is three-dimensional and based on an adapted external Eshelby solution. The slip surface is embedded in a homogeneous matrix, which is subjected to simple shear. Layers are introduced as passive markers for the visualization. With this method we tested the influence of the initial slip surface orientation (0°, 90°, or 135° with respect to the shear direction) and the number of layers on the evolving eye-structure. To study the effect of mechanical layering (viscosity contrast, layer thickness) on the geometry of the eye-structures we designed an experimental model using silicones as rock analogues. Although sheath folds are commonly considered as high strain markers, the analytical model shows that very little strain is needed to produce a sheath fold and the corresponding eye-pattern, and that the minimum strain is mainly dependent on the orientation of the slip surface and the number of layers. Our analytical as well as the experimental models revealed a sheath fold at both tips of the deformed slip surface. The two sheath folds show opposing closing direction

  7. Structure of the Type VI secretion system contractile sheath

    PubMed Central

    Kudryashev, Mikhail; Wang, Ray Yu-Ruei; Brackmann, Maximilian; Scherer, Sebastian; Maier, Timm; Baker, David; DiMaio, Frank; Stahlberg, Henning; Egelman, Edward H.; Basler, Marek

    2015-01-01

    Summary Bacteria use rapid contraction of a long sheath of the Type VI secretion system (T6SS) to deliver effectors into a target cell. Here we present an atomic resolution structure of a native contracted Vibrio cholerae sheath determined by cryo-electron microscopy. The sheath subunits, composed of tightly interacting proteins VipA and VipB, assemble into a six-start helix. The helix is stabilized by a core domain assembled from four β-strands donated by one VipA and two VipB molecules. The fold of inner and middle layers is conserved between T6SS and phage sheaths. However, the structure of the outer layer is distinct and suggests a mechanism of interaction of the bacterial sheath with an accessory ATPase, ClpV, that facilitates multiple rounds of effector delivery. Our results provide a mechanistic insight into assembly of contractile nanomachines that bacteria and phages use to translocate macromolecules across membranes. PMID:25723169

  8. Structural Conservation of the Myoviridae Phage Tail Sheath Protein Fold

    SciTech Connect

    Aksyuk, Anastasia A.; Kurochkina, Lidia P.; Fokine, Andrei; Forouhar, Farhad; Mesyanzhinov, Vadim V.; Tong, Liang; Rossmann, Michael G.

    2012-02-21

    Bacteriophage phiKZ is a giant phage that infects Pseudomonas aeruginosa, a human pathogen. The phiKZ virion consists of a 1450 {angstrom} diameter icosahedral head and a 2000 {angstrom}-long contractile tail. The structure of the whole virus was previously reported, showing that its tail organization in the extended state is similar to the well-studied Myovirus bacteriophage T4 tail. The crystal structure of a tail sheath protein fragment of phiKZ was determined to 2.4 {angstrom} resolution. Furthermore, crystal structures of two prophage tail sheath proteins were determined to 1.9 and 3.3 {angstrom} resolution. Despite low sequence identity between these proteins, all of these structures have a similar fold. The crystal structure of the phiKZ tail sheath protein has been fitted into cryo-electron-microscopy reconstructions of the extended tail sheath and of a polysheath. The structural rearrangement of the phiKZ tail sheath contraction was found to be similar to that of phage T4.

  9. Revisiting the plasma sheath—dust in plasma sheath

    NASA Astrophysics Data System (ADS)

    Das, G. C.; Deka, R.; Bora, M. P.

    2016-04-01

    In this work, we have considered the formation of warm plasma sheath in the vicinity of a wall in a plasma with considerable presence of dust particles. As an example, we have used the parameters relevant in case of plasma sheath formed around surfaces of various solid bodies in space, though the results obtained in this work can be applied to any other physical situation such as laboratory plasma. In the ion-acoustic time scale, we neglect the dust dynamics. The dust particles affect the sheath dynamics by affecting the Poisson equation which determines the plasma potential in the sheath region. It is important to note that our calculations are valid only when the amount of dust particles is not sufficient so as to affect the plasma dynamics in the dust-acoustic time scale, but enough to affect the plasma sheath. We have assumed the current to a dust particle to be balanced throughout the analysis. This makes the grain potential dependent on plasma potential, which is then incorporated into the Poisson equation. The resultant numerical model becomes an initial value problem, which is described by a 1-D integro-differential equation, which is then solved self-consistently by incorporating the change in plasma potential caused by inclusion of the dust potential in the Poisson equation.

  10. An investigation of tendon sheathing filler migration into concrete

    SciTech Connect

    Naus, D.J.; Oland, C.B.

    1998-03-01

    During some of the inspections at nuclear power plants with prestressed concrete containments, it was observed that the containments has experienced leakage of the tendon sheathing filler (i.e., streaks). The objective of this activity was to provide an indication of the extent of tendon sheathing filler leakage into the concrete and its affects on concrete properties. Literature was reviewed and concrete core samples were obtained from the Trojan Nuclear Plant and tested. The literature primarily addressed effects of crude or lubricating oils that are known to cause concrete damage. However, these materials have significantly different characteristics relative to the materials used as tendon sheathing fillers. Examination and testing of the concrete cores indicated that the appearance of tendon sheathing filler on the concrete surface was due to leakage from the conduits and its subsequent migration through cracks that were present. Migration of the tendon sheathing filler was confined to the cracks and there was no perceptible movement into the concrete. Results of compressive strength testing indicated that the concrete quality was consistent in the containment and that the strength had increased over 40% in 25.4 years relative to the average compressive strength at 28-days age.

  11. Mitigating impact of rectified RF sheath potential on the ELMs

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Xu, Xueqiao; Xia, Tianyang

    2014-10-01

    Here we report on the BOUT++ simulation results for the mitigating impact of rectified RF sheath potential on the peeling-ballooning modes. The limiter and the RF wave antenna are placed at the outer middle plane in the scrape-off-layer (SOL) in shift-circle geometry. The external shear flow is induced by the limiter and the RF wave. Besides this, the sheath boundary conditions are imposed on the perturbed potential and parallel current. From the three-field simulations, it is found that the energy loss is suppressed by the external shear flow in the nonlinear phase. The external shear flow due to the RF wave leads to a broad turbulence spectrum. The wider spectrum leads to a weaker turbulence transport and results in a smaller energy loss. The perturbed electric potential and the parallel current near the sheath region are also suppressed locally due to the sheath boundary condition. Based on this work, this effect of limiter will also be applied in six-field which includes more physics effects. The effect of sheath boundary conditions on the thermal conductivities and heat flux will be studied. This work was performed for USDOE by LLNL under DE-AC52-07NA27344, LLNL LDRD project 12-ERD-022 and the China Natural Science Foundation under Contract No. 10721505. LLNL-ABS-657008.

  12. Measurement of effective sheath width around cutoff probe in low-pressure plasmas

    SciTech Connect

    Kim, D. W.; Oh, W. Y.; You, S. J. Kim, J. H.; Chang, H. Y.

    2014-05-15

    Previous studies indicated that the measurement results of microwave probes can be improved by applying the adequate sheath width to their measurement models, and consequently the sheath width around the microwave probe tips has become very important information for microwave probe diagnostics. In this paper, we propose a method for measuring the argon plasma sheath width around the cutoff probe tips by applying the circuit model to the cutoff probe phase spectrum. The measured sheath width of the cutoff probe was found to be in good agreement with the floated sheath width calculated from the Child-Langmuir sheath law. The physical reasons for a discrepancy between the two measurements are also discussed.

  13. Measurement of effective sheath width around cutoff probe in low-pressure plasmas

    NASA Astrophysics Data System (ADS)

    Kim, D. W.; You, S. J.; Kim, J. H.; Chang, H. Y.; Oh, W. Y.

    2014-05-01

    Previous studies indicated that the measurement results of microwave probes can be improved by applying the adequate sheath width to their measurement models, and consequently the sheath width around the microwave probe tips has become very important information for microwave probe diagnostics. In this paper, we propose a method for measuring the argon plasma sheath width around the cutoff probe tips by applying the circuit model to the cutoff probe phase spectrum. The measured sheath width of the cutoff probe was found to be in good agreement with the floated sheath width calculated from the Child-Langmuir sheath law. The physical reasons for a discrepancy between the two measurements are also discussed.

  14. A spine-sheath model for strong-line blazars

    NASA Astrophysics Data System (ADS)

    Sikora, Marek; Rutkowski, Mieszko; Begelman, Mitchell C.

    2016-04-01

    We have developed a quasi-analytical model for the production of radiation in strong-line blazars, assuming a spine-sheath jet structure. The model allows us to study how the spine and sheath spectral components depend on parameters describing the geometrical and physical structure of `the blazar zone'. We show that typical broad-band spectra of strong-line blazars can be reproduced by assuming the magnetization parameter to be of order unity and reconnection to be the dominant dissipation mechanism. Furthermore, we demonstrate that the spine-sheath model can explain why γ-ray variations are often observed to have much larger amplitudes than the corresponding optical variations. The model is also less demanding of jet power than one-zone models, and can reproduce the basic features of extreme γ-ray events.

  15. Wave rectification in plasma sheaths surrounding electric field antennas

    NASA Technical Reports Server (NTRS)

    Boehm, M. H.; Carlson, C. W.; Mcfadden, J. P.; Clemmons, J. H.; Ergun, R. E.; Mozer, F. S.

    1994-01-01

    Combined measurements of Langmuir or broadband whistler wave intensity and lower-frequency electric field waveforms, all at 10-microsecond time resolution, were made on several recent sounding rockets in the auroral ionosphere. It is found that Langmuir and whistler waves are partically rectified in the plasma sheaths surrounding the payload and the spheres used as antennas. This sheath rectification occurs whenever the high frequency (HF) potential across the sheath becomes of the same order as the electron temperature or higher, for wave frequencies near or above the ion plasma frequency. This rectification can introduce false low-frequency waves into measurements of electric field spectra when strong high-frequency waves are present. Second harmonic signals are also generated, although at much lower levels. The effect occurs in many different plasma conditions, primarily producing false waves at frequencies that are low enough for the antenna coupling to the plasma to be resistive.

  16. Photovoltaic sheathing element with a flexible connector assembly

    DOEpatents

    Langmaid, Joseph A; Keenihan, James R; Mills, Michael E; Lopez, Leonardo C

    2016-07-12

    The present invention is premised upon an assembly including at least a photovoltaic sheathing element capable of being affixed on a building structure, the sheathing element including at least: a photovoltaic cell assembly, a body portion attached to one or more portions of the photovoltaic cell assembly; at least a first and a second connector assembly disposed on opposing sides of the sheathing element and capable of directly or indirectly electrically connecting the photovoltaic cell assembly to at least two adjoining devices that are affixed to the building structure and wherein at least one of the connector assemblies includes a flexible portion; one or more connector pockets disposed in the body portion the pockets capable of receiving at least a portion of the connector assembly.

  17. Micro-Particles as Electrostatic Probes for Plasma Sheath Diagnostic

    SciTech Connect

    Wolter, Matthias; Haass, Moritz; Ockenga, Taalke; Kersten, Holger; Blazec, Joseph; Basner, Ralf

    2008-09-07

    An interesting aspect in the research of complex (dusty) plasmas is the experimental study of the interaction of micro-particles of different sizes with the surrounding plasma for diagnostic purpose. In the plasma micro-disperse particles are negatively charged and confined in the sheath. The particles are trapped by an equilibrium of gravity, electric field force and ion drag force. From the behavior, local electric fields can be determined, e.g. particles are used as electrostatic probes. In combination with additional measurements of the plasma parameters with Langmuir probes and thermal probes as well as by comparison with an analytical sheath model, the structure of the sheath can be described. In the present work we focus on the behavior of micro-particles of different sizes and several plasma parameters e.g. the gas pressure and the rf-power.

  18. Anomalous Capacitive Sheath with Deep Radio Frequency Electric Field Penetration

    SciTech Connect

    Igor D. Kaganovich

    2002-01-18

    A novel nonlinear effect of anomalously deep penetration of an external radio-frequency electric field into a plasma is described. A self-consistent kinetic treatment reveals a transition region between the sheath and the plasma. Because of the electron velocity modulation in the sheath, bunches in the energetic electron density are formed in the transition region adjusted to the sheath. The width of the region is of order V(subscript T)/omega, where V(subscript T) is the electron thermal velocity, and w is frequency of the electric field. The presence of the electric field in the transition region results in a cooling of the energetic electrons and an additional heating of the cold electrons in comparison with the case when the transition region is neglected.

  19. Sheath formation under collisional conditions in presence of dust

    SciTech Connect

    Moulick, R. Goswami, K. S.

    2014-08-15

    Sheath formation is studied for collisional plasma in presence of dust. In common laboratory plasma, the dust acquires negative charges because of high thermal velocity of the electrons. The usual dust charging theory dealing with the issue is that of the Orbit Motion Limited theory. However, the theory does not find its application when the ion neutral collisions are significantly present. An alternate theory exists in literature for collisional dust charging. Collision is modeled by constant mean free path model. The sheath is considered jointly with the bulk of the plasma and a smooth transition of the plasma profiles from the bulk to the sheath is obtained. The various plasma profiles such as the electrostatic force on the grain, the ion drag force along with the dust density, and velocity are shown to vary spatially with increasing ion neutral collision.

  20. Sheath dynamics and energetic particle distributions on substrates

    NASA Astrophysics Data System (ADS)

    Lieberman, Michael A.

    2009-10-01

    The energy and angular distributions (EAD's) of energetic particles arriving at a substrate determine crucial plasma processing characteristics; thus knowledge and control of the EAD's are vital for nanoelectronics design and fabrication during scale-down to the ultimate 4--6 nm transistor gate lengths over the next 15 years. We review the history and state-of-the-art of measurements, simulations, and analyses of ion, fast neutral, and ballistic electron EAD's. Ion measurements have been made using electrostatic energy analyzers, cylindrical mirror analyzers, and retarding grid analyzers, often now coupled with quadrupole mass spectrometers to compare different ions in the same discharge. The state-of-the-art for capacitive rf sheaths has advanced greatly since the first observation of a bi-modal ion energy distribution (IED) over 50 years ago. More recently, measurement techniques and models have been developed to determine fast neutral distributions. Monte Carlo, and particle-in-cell simulations with Monte Carlo collisions (PIC-MCC) have been used to study IED's since the late 1980's. Recently, PIC-MCC simulations were used to obtain ballistic electron EAD's. Analytical models of the IED for collisionless rf sheaths have emphasized the role of τi/τrf, the ratio of ion transit time across the sheath to rf period, with separate models for the low and high frequency regimes. Various simplifications and bridging models now exist. For collisional rf sheaths, the important role of λi/s, the ratio of ion-neutral mean free path to sheath width, in modifying the collisionless bi-modal IED was demonstrated in the early 1990's. Surface charging effects on insulating substrates are important for low frequency rf discharges or for pulsed transient sheaths; the latter are found during plasma ion implantation processes. Analytical models of the IED for plasma ion implantation have been extended to insulating surfaces and compared with experimental results.

  1. MOLYBDENUM DISILICIDE MATERIALS FOR GLASS MELTING SENSOR SHEATHS

    SciTech Connect

    J. PETROVIC; R. CASTRO; ET AL

    2001-01-01

    Sensors for measuring the properties of molten glass require protective sensor sheaths in order to shield them from the extremely corrosive molten glass environment. MoSi{sub 2} has been shown to possess excellent corrosion resistance in molten glass, making it a candidate material for advanced sensor sheath applications. MoSi{sub 2}-coated Al{sub 2}O{sub 3} tubes, MoSi{sub 2}-Al{sub 2}O{sub 3} laminate composite tubes, and MoSi{sub 2}-Al{sub 2}O{sub 3} functionally graded composite tubes have been produced by plasma spray-forming techniques for such applications.

  2. Photovoltaic building sheathing element with anti-slide features

    SciTech Connect

    Keenihan, James R.; Langmaid, Joseph A.; Lopez, Leonardo C.

    2015-09-08

    The present invention is premised` upon an assembly that includes at least a photovoltaic building sheathing element capable of being affixed on a building structure, the photovoltaic building sheathing element. The element including a photovoltaic cell assembly, a body portion attached to one or more portions of the photovoltaic cell assembly; and at feast a first and a second connector assembly capable of directly or indirectly electrically connecting the photovoltaic cell assembly to one or more adjoining devices; wherein the body portion includes one or more geometric features adapted to engage a vertically adjoining device before installation.

  3. Malignant peripheral nerve sheath tumor of the parotid gland.

    PubMed

    Chis, Octavian; Albu, Silviu

    2014-09-01

    Malignant peripheral nerve sheath tumor (MPNST) refers to spindle cell sarcomas arising from or separating in the direction of cells of the peripheral nerve sheath. The MPNST of the parotid gland is an extremely rare tumor, usually having a poor prognosis, and only a few cases been described in the literature. In this article, we report the diagnostic and therapeutic challenges related to a new case of MPNST of the parotid. Diagnosis was made based on clinical, imaging (computed tomography scan), histologic, and immunohistochemistry findings. Despite comprehensive treatment--complete surgical resection and radiotherapy--the tumor displayed a highly aggressive course. PMID:25153067

  4. Formation of pre-sheath boundary layers in electronegative plasmas

    SciTech Connect

    Vitello, P., LLNL

    1998-05-01

    In electronegative plasmas Coulomb scattering between positive and negative ions can lead to the formation of a pre-sheath boundary layer containing the bulk of the negative ions. The negative ion boundary layer forms when momentum transfer from positive to negative ions dominates the negative ion acceleration from the electric field. This condition is met in Inductively Coupled Plasma reactors that operate at low pressure and high plasma density. Simulations of the GEC reactor for Chlorine and Oxygen chemistries using the INDUCT95 2D model are presented showing the pre-sheath boundary layer structure as a function of applied power and neutral pressure.

  5. Radiation-induced malignant and atypical peripheral nerve sheath tumors

    SciTech Connect

    Foley, K.M.; Woodruff, J.M.; Ellis, F.T.; Posner, J.B.

    1980-04-01

    The reported peripheral nerve complications of therapeutic irradiation in humans include brachial and lumbar plexus fibrosis and cranial and peripheral nerve atrophy. We have encountered 9 patients with malignant (7) and atypical (2) peripheral nerve tumors occurring in an irradiated site suggesting that such tumors represent another delayed effect of radiation treatment on peripheral nerve. In all instances the radio-theray was within an acceptable radiation dosage, yet 3 patients developed local radiation-induced skin and bony abnormalities. The malignant peripheral nerve sheath tumors developed only in the radiation port. Animal studies support the clinical observation that malignant peripheral nerve sheath tumors can occur as a delayed effect of irradiation.

  6. Malignant Peripheral Nerve Sheath Tumor -A Rare Malignancy in Mandible

    PubMed Central

    Majumdar, Sumit; Kotina, Sreekanth; Uppala, Divya; Kumar, Singam Praveen

    2016-01-01

    Malignant Peripheral Nerve Sheath Tumor (MPNST) is biologically an aggressive tumor that is usually found in the extremities, trunk and infrequently found in the head and neck area particularly in the jaws, arising from the cells allied with nerve sheath. Mandibular MPNST may either arise from a preexisting neurofibroma or develop de novo. Because of the greater variability from case to case in overall appearance both clinically and histologically, a case of MPNST of the mandible in a 25-year-old female patient is reported. The lesion was excised and immunohistological studies (S-100 & Neuron specific enolase) were conducted to confirm the neural origin. PMID:27504425

  7. Malignant Peripheral Nerve Sheath Tumor -A Rare Malignancy in Mandible.

    PubMed

    Majumdar, Sumit; Kotina, Sreekanth; Mahesh, Nirujogi; Uppala, Divya; Kumar, Singam Praveen

    2016-06-01

    Malignant Peripheral Nerve Sheath Tumor (MPNST) is biologically an aggressive tumor that is usually found in the extremities, trunk and infrequently found in the head and neck area particularly in the jaws, arising from the cells allied with nerve sheath. Mandibular MPNST may either arise from a preexisting neurofibroma or develop de novo. Because of the greater variability from case to case in overall appearance both clinically and histologically, a case of MPNST of the mandible in a 25-year-old female patient is reported. The lesion was excised and immunohistological studies (S-100 & Neuron specific enolase) were conducted to confirm the neural origin. PMID:27504425

  8. Measurement of effective sheath width around the cutoff probe based on electromagnetic simulation

    NASA Astrophysics Data System (ADS)

    Kim, D. W.; You, S. J.; Kim, J. H.; Chang, H. Y.; Yoon, J.-S.; Oh, W. Y.

    2016-05-01

    We inferred the effective sheath width using the cutoff probe and incorporating a full-wave three-dimensional electromagnetic (EM) simulation. The EM simulation reproduced the experimentally obtained plasma-sheath resonance (PSR) on the microwave transmission (S21) spectrum well. The PSR frequency has a one-to-one correspondence with the width of the vacuum layer assumed to be the effective sheath in the EM simulation model. The sheath width was estimated by matching the S21 spectra of the experiment and the EM simulation for different widths of the sheath. We found that the inferred sheath widths quantitatively and qualitatively agree with the sheath width measured by incorporating an equivalent circuit model. These results demonstrate the excellent potential of the cutoff probe for inferring the effective sheath width from its experimental spectrum data.

  9. Bilateral Rectus Sheath Hematoma in Kidney Transplant Patient: Case Study and Literature Review

    PubMed Central

    Feizzadeh Kerigh, Behzad; Maddah, Ghodratolah

    2013-01-01

    Rectus sheath hematoma usually occurs unilateral but rare cases of bilateral hematoma have been reported. Herein we report the first case of spontaneous bilateral Rectus Sheath Hematoma in the kidney transplanted patient. PMID:24350093

  10. A suitable boundary condition for bounded plasma simulation without sheath resolution

    SciTech Connect

    Parker, S.E.; Procassini, R.J.; Birdsall, C.K. ); Cohen, B.I. )

    1993-01-01

    We have developed a technique that allows for a sheath boundary layer without having to resolve the inherently small space and time scales of the sheath region. We refer to this technique as the logical sheath boundary condition. This boundary condition, when incorporated into a direct-implicit particle code, permits large space- and time-scale simulations of bounded systems, which would otherwise be impractical on current supercomputers. The lack of resolution of the collector sheath potential drop obtained from conventional implicit simulations at moderate values of [omega][sub pe][Delta]t and [Delta]z/[lambda][sup De] provides the motivation for the development of the logical sheath boundary condition. The algorithm for use of the logical sheath boundary condition in a particle simulation is presented. Results from simulations which use the logical sheath boundary condition are shown to compare reasonably well with those from an analytic theory and simulations in which the sheath is resolved.

  11. Effect of secondary electron emission on the plasma sheath

    SciTech Connect

    Langendorf, S. Walker, M.

    2015-03-15

    In this experiment, plasma sheath potential profiles are measured over boron nitride walls in argon plasma and the effect of secondary electron emission is observed. Results are compared to a kinetic model. Plasmas are generated with a number density of 3 × 10{sup 12} m{sup −3} at a pressure of 10{sup −4} Torr-Ar, with a 1%–16% fraction of energetic primary electrons. The sheath potential profile at the surface of each sample is measured with emissive probes. The electron number densities and temperatures are measured in the bulk plasma with a planar Langmuir probe. The plasma is non-Maxwellian, with isotropic and directed energetic electron populations from 50 to 200 eV and hot and cold Maxwellian populations from 3.6 to 6.4 eV and 0.3 to 1.3 eV, respectively. Plasma Debye lengths range from 4 to 7 mm and the ion-neutral mean free path is 0.8 m. Sheath thicknesses range from 20 to 50 mm, with the smaller thickness occurring near the critical secondary electron emission yield of the wall material. Measured floating potentials are within 16% of model predictions. Measured sheath potential profiles agree with model predictions within 5 V (∼1 T{sub e}), and in four out of six cases deviate less than the measurement uncertainty of 1 V.

  12. Internal pressure effects in the AIRCO-LCT conductor sheath

    SciTech Connect

    Luton, J.N.; Clinard, J.A.; Lue, J.W.; Gray, W.H.; Summers, L.T.; Kershaw, R.

    1985-01-01

    The large Nb/sub 3/Sn superconducting test coil produced by Westinghouse Electric Corporation for the international Large Coil Task (LCT) utilizes a conductor composed of cabled multifilamentary strands immersed in flowing supercritical helium contained by a square structural sheath made of the high-strength stainless alloy JBX-75. Peak pressures of a few hundred atmospheres are predicted to occur during quench, and measurement of these pressures seems feasible only through penetrations of the sheath wall. Fully processed short lengths of conductor were taken from production ends, fitted with pressure taps and strain gauges, and pressurized with helium gas. Failure, at 1000 atm at liquid nitrogen temperature, was by a catastrophic splitting of the sheath at a corner. Strain measurements and burst pressure agreed with elastic-plastic finite element stress calculations made for the sheath alone. Neither the production seam weld nor the pressure tap penetrations or their fillet welds contributed to the failure, although the finite element calculations show that these areas were also highly stressed, and examination of the failed sample showed that the finite welds were of poor quality. Failure was by tensile overload, with no evidence of fatigue.

  13. Separation system with a sheath-flow supported electrochemical detector

    DOEpatents

    Mathies, Richard A.; Emrich, Charles A.; Singhal, Pankaj; Ertl, Peter

    2008-10-21

    An electrochemical detector including side channels associated with a separation channel of a sample component separation apparatus is provided. The side channels of the detector, in one configuration, provide a sheath-flow for an analyte exiting the separation channel which directs the analyte to the electrically developed electrochemical detector.

  14. Modeling a planar sheath in dust-containing plasmas

    SciTech Connect

    Chung, T. H.

    2014-01-15

    One-dimensional fluid model is utilized to describe the sheath at a dust-containing plasma-wall boundary. The model equations are solved on the scale of the electron Debye length. The spatial distributions of electric potential and of the velocities and densities of charged species are calculated in a wide range of control parameters. The dust charge number, electric force, and ion drag force are also investigated. The impacts of Havnes parameter, the electron to ion temperature ratio, the ion collisionality, and the ionization on the spatial distributions of the plasma species and the incident fluxes of the ions to the wall (or to the probe) are investigated. With increase of Havnes parameter, the sheath thickness and the ion flux to the wall are reduced, whereas the ion drift velocity is increased. Enhanced ion thermal motion causes the ion flux to the wall to increase. An increase in ion collisionality with neutrals causes both the sheath thickness and the ion flux to the wall to decrease. With increase of the ionization rate, the sheath thickness is found to decrease and the ion flux collected by a probe increases. The localization of dust particles above the electrode is intensified by the increases in Havnes parameter, the electron to ion temperature ratio, collisionality, and ionization rate.

  15. The Confinement and Sheath Within a Glass Box

    NASA Astrophysics Data System (ADS)

    Chen, Mudi; Dropmann, Michael; Kong, Jie; Qiao, Ke; Carmona-Reyes, Jorge; Matthews, Lorin; Hyde, Truell

    2015-11-01

    The confinement structure provided by a glass box placed on the lower powered electrode of a GEC rf Reference Cell is proving to be ideal for the formation of vertically aligned structures which are often difficult to obtain under other types of confinement. A glass box also provides a mechanism for controlling the number of dust particles comprising a particular dust structure as well as their size and symmetry. However, given the small volume of the glass box and the fact that each of the glass panes comprising the box develop a new sheath within the plasma environment, the structure of the overall sheath inside is quite different from that produced by the lower electrode alone. Since both the confinement and sheath structure are vital for producing ordered dust particle structures, a better understanding of the underlying physics is sorely needed. In this experiment, the trajectories of dust particles acting as probes while falling through the glass box under various plasma environments are tracked and analyzed. It will be shown that the resulting data provides a map of both the confining force and the structure of the sheath inside the glass box. Support from the NSF and the DOE (award numbers PHY-1262031 and PHY-1414523) is gratefully acknowledged.

  16. Studies of RF sheaths and diagnostics on IShTAR

    NASA Astrophysics Data System (ADS)

    Crombé, K.; Devaux, S.; D'Inca, R.; Faudot, E.; Faugel, H.; Fünfgelder, H.; Heuraux, S.; Jacquot, J.; Louche, F.; Moritz, J.; Ochoukov, R.; Tripsky, M.; Van Eester, D.; Wauters, T.; Noterdaeme, J.-M.

    2015-12-01

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed to excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.

  17. Double polymer sheathed carbon nanotube supercapacitors show enhanced cycling stability

    NASA Astrophysics Data System (ADS)

    Zhao, Wenqi; Wang, Shanshan; Wang, Chunhui; Wu, Shiting; Xu, Wenjing; Zou, Mingchu; Ouyang, An; Cao, Anyuan; Li, Yibin

    2015-12-01

    Pseudo-materials are effective in boosting the specific capacitance of supercapacitors, but during service their degradation may also be very strong, causing reduced cycling stability. Here, we show that a carbon nanotube sponge grafted by two conventional pseudo-polymer layers in sequence can serve as a porous supercapacitor electrode with significantly enhanced cycling stability compared with single polymer grafting. Creating conformal polymer coatings on the nanotube surface and the resulting double-sheath configuration are important structural factors leading to the enhanced performance. Combining different polymers as double sheaths as reported here might be a potential route to circumvent the dilemma of pseudo-materials, and to simultaneously improve the capacitance and stability for various energy storage devices.Pseudo-materials are effective in boosting the specific capacitance of supercapacitors, but during service their degradation may also be very strong, causing reduced cycling stability. Here, we show that a carbon nanotube sponge grafted by two conventional pseudo-polymer layers in sequence can serve as a porous supercapacitor electrode with significantly enhanced cycling stability compared with single polymer grafting. Creating conformal polymer coatings on the nanotube surface and the resulting double-sheath configuration are important structural factors leading to the enhanced performance. Combining different polymers as double sheaths as reported here might be a potential route to circumvent the dilemma of pseudo-materials, and to simultaneously improve the capacitance and stability for various energy storage devices. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr05978j

  18. Dust-Plasma Sheath in an Oblique Magnetic Field

    SciTech Connect

    Foroutan, G.; Mehdipour, H.

    2008-09-07

    Using numerical simulations of the multi fluid equations the structure of the magnetized sheath near a plasma boundary is studied in the presence of charged dust particles. The dependence of the electron, ion, and dust densities as well as the electrostatic potential, dust charge, and ion normal velocity, on the magnetic field strength and the edge dust number density is investigated.

  19. High-frequency instability of the sheath-plasma resonance

    NASA Technical Reports Server (NTRS)

    Stenzel, R. L.

    1989-01-01

    Coherent high frequency oscillations near the electron plasma frequency (omega approx. less than omega sub p) are generated by electrodes with positive dc bias immersed in a uniform Maxwellian afterglow plasma. The instability occurs at the sheath-plasma resonance and is driven by a negative RF sheath resistance associated with the electron inertia in the diode-like electron-rich sheath. With increasing dc bias, i.e., electron transit time, the instability exhibits a hard threshold, downward frequency pulling, line broadening and copious harmonics. The fundamental instability is a bounded oscillation due to wave evanescence, but the harmonics are radiated as electromagnetic waves from the electrodes acting like antennas. Wavelength and polarization measurements confirm the emission process. Electromagnetic waves are excited by electrodes of various geometries (planes, cylinders, spheres) which excludes other radiation mechanisms such as orbitrons or beam-plasma instabilities. The line broadening mechanism was identified as a frequency modulation via the electron transit time by dynamic ions. Ion oscillations at the sheath edge give rise to burst-like RF emissions. These laboratory observations of a new instability are important for antennas in space plasmas, generation of coherent beams with diodes, and plasma diagnostics.

  20. On the upper bound in the Bohm sheath criterion

    NASA Astrophysics Data System (ADS)

    Kotelnikov, I. A.; Skovorodin, D. I.

    2016-02-01

    The question is discussed about the existence of an upper bound in the Bohm sheath criterion, according to which the Debye sheath at the interface between plasma and a negatively charged electrode is stable only if the ion flow velocity in plasma exceeds the ion sound velocity. It is stated that, with an exception of some artificial ionization models, the Bohm sheath criterion is satisfied as an equality at the lower bound and the ion flow velocity is equal to the speed of sound. In the one-dimensional theory, a supersonic flow appears in an unrealistic model of a localized ion source the size of which is less than the Debye length; however, supersonic flows seem to be possible in the two- and three-dimensional cases. In the available numerical codes used to simulate charged particle sources with a plasma emitter, the presence of the upper bound in the Bohm sheath criterion is not supposed; however, the correspondence with experimental data is usually achieved if the ion flow velocity in plasma is close to the ion sound velocity.

  1. Effect of secondary electron emission on the plasma sheath

    NASA Astrophysics Data System (ADS)

    Langendorf, S.; Walker, M.

    2015-03-01

    In this experiment, plasma sheath potential profiles are measured over boron nitride walls in argon plasma and the effect of secondary electron emission is observed. Results are compared to a kinetic model. Plasmas are generated with a number density of 3 × 1012 m-3 at a pressure of 10-4 Torr-Ar, with a 1%-16% fraction of energetic primary electrons. The sheath potential profile at the surface of each sample is measured with emissive probes. The electron number densities and temperatures are measured in the bulk plasma with a planar Langmuir probe. The plasma is non-Maxwellian, with isotropic and directed energetic electron populations from 50 to 200 eV and hot and cold Maxwellian populations from 3.6 to 6.4 eV and 0.3 to 1.3 eV, respectively. Plasma Debye lengths range from 4 to 7 mm and the ion-neutral mean free path is 0.8 m. Sheath thicknesses range from 20 to 50 mm, with the smaller thickness occurring near the critical secondary electron emission yield of the wall material. Measured floating potentials are within 16% of model predictions. Measured sheath potential profiles agree with model predictions within 5 V (˜1 Te), and in four out of six cases deviate less than the measurement uncertainty of 1 V.

  2. [Fitting a male sheath urinal while respecting the patient's intimacy].

    PubMed

    Derville, Sandrine; Cellard Du Sordet, Paul; Breuzard, Magali; Béguin, Anne-Marie; Malaquin-Pavan, Evelyne

    2015-04-01

    The fitting of a male sheath urinal directly concerns the patient's area of sexual intimacy. The modesty of the patient and caregiver as they interact is tested, leading to discomfort or clumsiness which can provoke a feeling of intrusion. Preparing this care procedure favours the adherence of both parties. PMID:26043631

  3. Rice Sheath Rot: An Emerging Ubiquitous Destructive Disease Complex

    PubMed Central

    Bigirimana, Vincent de P.; Hua, Gia K. H.; Nyamangyoku, Obedi I.; Höfte, Monica

    2015-01-01

    Around one century ago, a rice disease characterized mainly by rotting of sheaths was reported in Taiwan. The causal agent was identified as Acrocylindrium oryzae, later known as Sarocladium oryzae. Since then it has become clear that various other organisms can cause similar disease symptoms, including Fusarium sp. and fluorescent pseudomonads. These organisms have in common that they produce a range of phytotoxins that induce necrosis in plants. The same agents also cause grain discoloration, chaffiness, and sterility and are all seed-transmitted. Rice sheath rot disease symptoms are found in all rice-growing areas of the world. The disease is now getting momentum and is considered as an important emerging rice production threat. The disease can lead to variable yield losses, which can be as high as 85%. This review aims at improving our understanding of the disease etiology of rice sheath rot and mainly deals with the three most reported rice sheath rot pathogens: S. oryzae, the Fusarium fujikuroi complex, and Pseudomonas fuscovaginae. Causal agents, pathogenicity determinants, interactions among the various pathogens, epidemiology, geographical distribution, and control options will be discussed. PMID:26697031

  4. A novel nonpharmacologic technique to remove entrapped radial sheath.

    PubMed

    Pancholy, Samir B; Karuparthi, Poorna Rajasekhar; Gulati, Rajiv

    2015-01-01

    Radial artery access for performance of coronary and peripheral diagnostic as well as interventional procedures is on the rise. With increasing adoption comes the expected increase in procedural complications. We describe a novel, simple, and effective nonpharmacologic solution for sheath entrapment related to pharmaco-resistant radial artery spasm. © 2014 Wiley Periodicals, Inc. PMID:25045106

  5. Sheath flow SERS for chemical profiling in urine.

    PubMed

    Riordan, Colleen M; Jacobs, Kevin T; Negri, Pierre; Schultz, Zachary D

    2016-06-23

    The molecular specificity and sensitivity of surface enhanced Raman scattering (SERS) makes it an attractive method for biomedical diagnostics. Here we present results demonstrating the utility and complications for SERS characterization in urine. The chemical fingerprint characteristics of Raman spectra suggest its use as a label free diagnostic; however, the complex composition of biological fluids presents a tremendous challenge. In particular, the limited number of surface sites and competing absorption tend to mask the presence of analytes in solution, particularly when the solution contains multiple analytes. To address these problems and characterize biological fluids we have demonstrated a sheath-flow interface for SERS detection. This sheath-flow SERS interface uses hydrodynamic focusing to confine analyte molecules eluting out of a column onto a planar SERS substrate where the molecules are detected by their intrinsic SERS signal. In this report we compare the direct detection of benzoylecgonine in urine using DSERS with chemical profiling by capillary zone electrophoresis and sheath-flow SERS detection. The SERS spectrum from the observed migration peaks can identify benzoylecgonine and other distinct spectra are also observed, suggesting improved chemical diagnostics in urine. With over 2000 reported compounds in urine, identification of each of the detected species is an enormous task. Nonetheless, these samples provide a benchmark to establish the potential clinical utility of sheath-flow SERS detection. PMID:27034996

  6. 46 CFR 111.05-7 - Armored and metallic sheathed cable.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... Armored and metallic sheathed cable. When installed, the metallic armor or sheath must meet the installation requirements of Section 25 of IEEE 45-2002 (incorporated by reference; see 46 CFR 110.10-1). ... 46 Shipping 4 2013-10-01 2013-10-01 false Armored and metallic sheathed cable. 111.05-7...

  7. 46 CFR 111.05-7 - Armored and metallic sheathed cable.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... Armored and metallic sheathed cable. When installed, the metallic armor or sheath must meet the installation requirements of Section 25 of IEEE 45-2002 (incorporated by reference; see 46 CFR 110.10-1). ... 46 Shipping 4 2012-10-01 2012-10-01 false Armored and metallic sheathed cable. 111.05-7...

  8. 46 CFR 111.05-7 - Armored and metallic sheathed cable.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... Armored and metallic sheathed cable. When installed, the metallic armor or sheath must meet the installation requirements of Section 25 of IEEE 45-2002 (incorporated by reference; see 46 CFR 110.10-1). ... 46 Shipping 4 2011-10-01 2011-10-01 false Armored and metallic sheathed cable. 111.05-7...

  9. Do counts of salivary sheath flanges predict food consumption in herbivorous stink bugs [Hemiptera: Pentatomidae]?

    Technology Transfer Automated Retrieval System (TEKTRAN)

    For Pentatomid stink bug agricultural pests, the number of salivary sheaths and sheath flanges—the portion of the sheath visible on the exterior surface of a food item—are good predictors of the loss of crop yield or quality from stink bug feeding. As the often assumed relationship between salivary ...

  10. 30 CFR 15.32 - Tolerances for weight of explosive, sheath, wrapper, and specific gravity.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ..., wrapper, and specific gravity. 15.32 Section 15.32 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... explosive, sheath, wrapper, and specific gravity. (a) The weight of the explosive, the sheath, and the outer.... (c) The specific gravity of the explosive and sheath shall be within ±7.5 percent of that...

  11. 30 CFR 15.32 - Tolerances for weight of explosive, sheath, wrapper, and specific gravity.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ..., wrapper, and specific gravity. 15.32 Section 15.32 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... explosive, sheath, wrapper, and specific gravity. (a) The weight of the explosive, the sheath, and the outer.... (c) The specific gravity of the explosive and sheath shall be within ±7.5 percent of that...

  12. 30 CFR 15.32 - Tolerances for weight of explosive, sheath, wrapper, and specific gravity.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., wrapper, and specific gravity. 15.32 Section 15.32 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... explosive, sheath, wrapper, and specific gravity. (a) The weight of the explosive, the sheath, and the outer.... (c) The specific gravity of the explosive and sheath shall be within ±7.5 percent of that...

  13. 30 CFR 15.32 - Tolerances for weight of explosive, sheath, wrapper, and specific gravity.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., wrapper, and specific gravity. 15.32 Section 15.32 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... explosive, sheath, wrapper, and specific gravity. (a) The weight of the explosive, the sheath, and the outer.... (c) The specific gravity of the explosive and sheath shall be within ±7.5 percent of that...

  14. 30 CFR 15.32 - Tolerances for weight of explosive, sheath, wrapper, and specific gravity.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ..., wrapper, and specific gravity. 15.32 Section 15.32 Mineral Resources MINE SAFETY AND HEALTH ADMINISTRATION... explosive, sheath, wrapper, and specific gravity. (a) The weight of the explosive, the sheath, and the outer.... (c) The specific gravity of the explosive and sheath shall be within ±7.5 percent of that...

  15. Introduction: Evidence-based in vitro fertilization treatment of fresh versus frozen embryo transfer: peeling away the layers of the onion.

    PubMed

    Legro, Richard S

    2016-08-01

    This introduction to this Views and Reviews examines the current evidence for elective fresh versus frozen embryo transfer, delineates complexities that arise as we sift through the available evidence, and speculates on the ideal design of studies to arrive at an evidence-based consensus. Current gaps in the literature, including a lack of reporting on important outcomes such as live birth and maternal and perinatal adverse events, are noted. The difficulty in designing trials is reviewed, including the choice of the time point in the cycle to randomize patients, how to account for all the patients and embyros that are involved in the trial, whether to incorporate prenatal genetic screening, and the best type of study design to address the risk/benefit ratio of these practices. PMID:27421612

  16. Sheath folds as discriminators of bulk strain type

    NASA Astrophysics Data System (ADS)

    Alsop, G. I.; Holdsworth, R. E.

    2006-09-01

    Nested elliptical closures defining "eye-folds" represent classic ( y- z) cross sections through highly curvilinear sheath folds generated during intense ductile deformation in metamorphic rocks. Systematic analysis of 1425 such eye-folds based on our own field observations and examples from the published literature reveals distinct and consistent differences in ellipticites measured from the outer- ( R yz) to the inner-most ( Ry' z' ) elliptical "rings" of individual sheaths. The variation in overall aspect ratios from outer to inner rings is defined as R' (where R' = R yz/ Ry' z' ) and may display a relative increase or decrease in ellipticity to define ' cats-eye' ( R' < 1) or ' bulls-eye' ( R' > 1) fold patterns respectively. Layer thicknesses may also be measured along the y axis (parallel to the axial surface) ( t y) and at 90° to this along the z axis ( t z) to define the ratio of T yz. Sheath folds generated during broadly simple shear deformation ( k ≅ 1) display (mean) R yz 4.61, T yz 3.31 and cats-eye-folds ( R' 0.69). Sheath folds generated during general shear also display cats-eye-folds with identical mean R' 0.69 values, but greater thickness variations and elliptical ratios ( T yz 4.35, R yz 5.76). Thus, within both simple- and general shear-dominated deformations, the overall variation in layer thickness ( T yz) and ellipticity of eye-folds ( R yz) increases with increasing deformation and a greater component of pure shear, whilst the R' value remains constant and reflects original fold patterns. Sheath folds formed during constrictional ( k > 1) deformation display markedly lower aspect ratios ( R yz 2.42) and thickness variations ( T yz 2.94), together with distinctive bulls-eye-folds ( R' 1.23). These empirical relationships suggest fundamental and universal constraints on curvilinear fold generation across this broad spectrum of deformation types, and allow sheath folds to act as both effective (>95% consistent) and robust discriminators of

  17. The magnetized sheath of a dusty plasma with grains size distribution

    SciTech Connect

    Ou, Jing Gan, Chunyun; Lin, Binbin; Yang, Jinhong

    2015-05-15

    The structure of a plasma sheath in the presence of dust grains size distribution (DGSD) is investigated in the multi-fluid framework. It is shown that effect of the dust grains with different sizes on the sheath structure is a collective behavior. The spatial distributions of electric potential, the electron and ion densities and velocities, and the dust grains surface potential are strongly affected by DGSD. The dynamics of dust grains with different sizes in the sheath depend on not only DGSD but also their radius. By comparison of the sheath structure, it is found that under the same expected value of DGSD condition, the sheath length is longer in the case of lognormal distribution than that in the case of uniform distribution. In two cases of normal and lognormal distributions, the sheath length is almost equal for the small variance of DGSD, and then the difference of sheath length increases gradually with increase in the variance.

  18. Plasma sheath effects and voltage distributions of large high-power satellite solar arrays

    NASA Technical Reports Server (NTRS)

    Parker, L. W.

    1979-01-01

    Knowledge of the floating voltage configuration of a large array in orbit is needed in order to estimate various plasma-interaction effects. The equilibrium configuration of array voltages relative to space depends on the sheath structure. The latter dependence for an exposed array is examined in the light of two finite-sheath effects. One effect is that electron currents may be seriously underestimated. The other is that a potential barrier for electrons can occur, restricting electron currents. A conducting surface is assumed on the basis of a conductivity argument. Finite-sheath effects are investigated. The results of assuming thin-sheath and thick-sheath limits on the floating configuration of a linearly connected array are studied. Sheath thickness and parasitic power leakage are estimated. Numerically computed fields using a 3-D code are displayed in the thick-sheath limit.

  19. The positive ion temperature effect in magnetized electronegative plasma sheath with two species of positive ions

    SciTech Connect

    Shaw, A. K.; Kar, S.; Goswami, K. S.

    2012-10-15

    The properties of a magnetized multi-component (two species of positive ions, negative ions and electrons) plasma sheath with finite positive ion temperature are studied. By using three fluid hydrodynamic model and some dimensionless variables, the ion (both lighter and heavier positive ions, and negative ions) densities, the ion (only for positive ions) velocities, and electric potential inside the sheath are investigated. In addition, the absence and presence of magnetic field and the orientation of magnetic field are considered. It is noticed that, with increase of positive ion temperature, the lighter positive ion density peaks increase only at the sheath edge and shift towards the sheath edge for both absence and presence of magnetic field. For heavier positive ions, in the absence of magnetic field, the density peaks increase at the sheath edge. But in the presence of magnetic field, the density fluctuations increase at the sheath edge. For both the cases, the density peaks shift towards the sheath edge.

  20. Moisture Durability with Vapor-Permeable Insulating Sheathing

    SciTech Connect

    Lepage, R.; Lstiburek, J.

    2013-09-01

    Exterior sheathing insulation is an effective strategy in increasing the overall R-value of wall assemblies; other benefits include decreasing the effects of thermal bridging and increasing the moisture durability of the built assembly. Vapor-permeable exterior insulation, such as mineral board or expanded polystyrene foam, are one such product that may be used to achieve these benefits. However,uncertainty exists on the effects of inward driven moisture and the interaction of increased sheathing temperatures on the moisture durability of the edifice. To address these concerns, Building Science Corporation (BSC) conducted a series of hygrothermal models for cities representing a range of different climate zones. This report describes the research project, key research questions, and theprocedures utilized to analyse the problems.

  1. Moisture Durability with Vapor-Permeable Insulating Sheathing

    SciTech Connect

    Lepage, R.; Lstiburek, J.

    2013-09-01

    Exterior sheathing insulation is an effective strategy in increasing the overall R-value of wall assemblies; other benefits include decreasing the effects of thermal bridging and increasing the moisture durability of the built assembly. Vapor-permeable exterior insulation, such as mineral board or expanded polystyrene foam, are one such product that may be used to achieve these benefits. However, uncertainty exists on the effects of inward driven moisture and the interaction of increased sheathing temperatures on the moisture durability of the edifice. To address these concerns, Building Science Corporation (BSC) conducted a series of hygrothermal models for cities representing a range of different climate zones. This report describes the research project, key research questions, and the procedures utilized to analyse the problems.

  2. Role of magnetic field tangency points in ICRF sheath interactions

    SciTech Connect

    Myra, J. R.; D'Ippolito, D. A.; Kohno, H.

    2014-02-12

    ICRF waves can sometimes interact with plasma-facing surfaces in tokamak fusion experiments causing degradation of core heating efficiency, impurity injection and even component damage. While presently available low dimensionality rf sheath models are useful in understanding many features of these interactions, more quantitative modeling will require attention to realistic geometrical details of the boundary plasma and surfaces. In this paper, we explore the situation in which there exists a tangency point of the background magnetic field with a surface. We find that the rf interactions are strongly influenced by the generation and propagation of sheath-plasma waves (SPW) along the surface. It is found that these waves preferentially propagate towards, and accumulate at, a convex tangency point. An analytical theory of SPW propagation is developed to understand these features.

  3. [Unusual location of a parathyroid adenoma: the carotid sheath].

    PubMed

    Smayra, T; Abi Khalil, S; Abboud, B; Halabi, G; Slaba, S

    2006-01-01

    We report the imaging features of an occult parathyroid adenoma with unusual location in the carotid sheath. Our patient presented with primary hyperparathyroidism. Following negative neck ultrasound and scintigraphy, exploratory neck dissection with partial thyroidectomy was performed twice over a 2 day period without biological response. Cervical and mediastinal CT and MRI were performed with no result. Digital angiography showed a tumoral blush supplied by the left inferior thyroid artery and located in close contact with the carotid artery. Venous sampling of the neck confirmed the left location of the adenoma and a third surgical intervention found the adenoma embedded in the left carotid sheath. This is an unusual case of parathyroid adenoma that necessitated the use of several imaging techniques. PMID:16415782

  4. Role of magnetic field tangency points in ICRF sheath interactions

    NASA Astrophysics Data System (ADS)

    Myra, J. R.; D'Ippolito, D. A.; Kohno, H.

    2014-02-01

    ICRF waves can sometimes interact with plasma-facing surfaces in tokamak fusion experiments causing degradation of core heating efficiency, impurity injection and even component damage. While presently available low dimensionality rf sheath models are useful in understanding many features of these interactions, more quantitative modeling will require attention to realistic geometrical details of the boundary plasma and surfaces. In this paper, we explore the situation in which there exists a tangency point of the background magnetic field with a surface. We find that the rf interactions are strongly influenced by the generation and propagation of sheath-plasma waves (SPW) along the surface. It is found that these waves preferentially propagate towards, and accumulate at, a convex tangency point. An analytical theory of SPW propagation is developed to understand these features.

  5. Collisionless "thermalization" in the sheath of an argon discharge

    NASA Astrophysics Data System (ADS)

    Coulette, David; Manfredi, Giovanni

    2015-04-01

    We performed kinetic Vlasov simulations of the plasma-wall transition for a low-pressure argon discharge without external magnetic fields, using the same plasma parameters as in the experiments of Claire et al. [Phys. Plasmas 13, 062103 (2006)]. Experimentally, it was found that the ion velocity distribution function is highly asymmetric in the presheath, but, surprisingly, becomes again close to Maxwellian inside the sheath. Here, we show that this "thermalization" can be explained by purely collisionless effects that are akin to the velocity bunching phenomenon observed in charged particles beams. Such collisionless thermalization is also observed in the presheath region close to the sheath entrance, although it is much weaker there and in practice probably swamped by collisional processes (standard or enhanced by instabilities).

  6. Spontaneous intraperitoneal rupture of a postpartum rectus sheath haematoma.

    PubMed

    Elmoghrabi, Adel; Mohamed, Mohamed; McCann, Michael; Sachwani-Daswani, Gul

    2016-01-01

    A 35-year-old woman presented to the emergency department (ED) with acute severe abdominal pain at 4 days postpartum. CT of the abdomen revealed a type II rectus sheath haematoma for which she was initially treated conservatively and discharged. A few hours later, she returned to the ED with a picture suggestive of peritonitis. Exploratory laparoscopy was performed and revealed haemoperitoneum and a ruptured area on the posterior rectus sheath. Approximately 2 L of blood was aspirated. Haemostatic control was achieved and closed suction drains secured in position. The patient was discharged in stable condition on postadmission day 6. She continued to follow-up on an outpatient basis and was doing well 3 months postoperatively. PMID:26961567

  7. Mapping and validation of QTLs for rice sheath blight resistance.

    PubMed

    Taguchi-Shiobara, Fumio; Ozaki, Hidenobu; Sato, Hiroyuki; Maeda, Hiroaki; Kojima, Yoichiro; Ebitani, Takeshi; Yano, Masahiro

    2013-09-01

    Sheath blight, caused by Rhizoctonia solani, is one of the most serious diseases of rice. Among 33 rice accessions, mainly from National Institute of Agrobiological Sciences (NIAS) Core Collection, we found three landraces from the Himalayas-Jarjan, Nepal 555 and Nepal 8-with resistance to sheath blight in 3 years' field testing. Backcrossed inbred lines (BILs) derived from a cross between Jarjan and the leading Japanese cultivar Koshihikari were used in QTL analyses. Since later-heading lines show fewer lesions, we used only earlier-heading BILs to avoid association with heading date. We detected eight QTLs; the Jarjan allele of three of these increased resistance. Only one QTL, on chromosome 9 (between markers Nag08KK18184 and Nag08KK18871), was detected in all 3 years. Chromosome segment substitution lines (CSSLs) carrying it showed resistance in field tests. Thirty F2 lines derived from a cross between Koshihikari and one CSSL supported the QTL. PMID:24273425

  8. Surgery for ganglia of the flexor tendon sheath

    PubMed Central

    Finsen, Vilhjalmur; Håberg, Øyvind; Borchgrevink, Grethe Elisabeth

    2013-01-01

    There are very few reports in the literature on the results of surgery for ganglia of the flexor tendon sheaths of the digits. We reviewed 24 patients operated for flexor tendon sheath ganglia 8 (3–11) years previously. Two operations were for recurrences and one of these recurred again. There was one permanent digital nerve injury and one patient complained of cold sensibility. VAS (0=best; 100=worst) for mean general complaints from the hand was remembered as 51 before surgery and was 5 at review. Mean pain at review was reported as VAS 4 and general satisfaction with the operation as VAS 3. All stated that they would have consented to surgery if they had known the outcome in advance. We conclude that the results of surgery are good, although complications do occur. PMID:23705064

  9. Silver sheathing of high-Tc superconductor wires

    NASA Astrophysics Data System (ADS)

    Wu, C. T.; Risch, G. A.; Poeppel, R. B.; Goretta, K. C.; Danyluk, S.; Herro, H. M.

    1990-10-01

    The properties of Ag sheaths on high-temperature super-conductors are examined. Ag is chemically compatible with YBa2Cu3O(x) and Bi-based superconductors can be safely coprocessed with them. Residual stresses created by differences in thermal expansion coefficients are favorable and can be controlled by proper annealing. Although Ag forms low-resistance contact with high temperature superconductors, it is not certain that effective cryogenic stabilization by Ag can occur at 77 K and above.

  10. INTERIOR OF HOG BARN SHOWING MILKING STANCHIONS AND DIAGONAL SHEATHING, ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    INTERIOR OF HOG BARN SHOWING MILKING STANCHIONS AND DIAGONAL SHEATHING, LOOKING EAST. (In the 1940s the hog barn was converted to a calf barn to service the growing dairy. After a fire on the property took the Engle’s main barn in 1954, the building was converted into a milking parlor.) - Engle Farm, Barn, 89 South Ebey Road, Coupeville, Island County, WA

  11. Studies of RF sheaths and diagnostics on IShTAR

    SciTech Connect

    Crombé, K.; D’Inca, R.; Faugel, H.; Fünfgelder, H.; Jacquot, J.; Ochoukov, R.; Louche, F.; Tripsky, M.; Van Eester, D.; Wauters, T.

    2015-12-10

    IShTAR (Ion cyclotron Sheath Test ARrangement) is a linear magnetised plasma test facility for RF sheaths studies at the Max-Planck-Institut für Plasmaphysik in Garching. In contrast to a tokamak, a test stand provides more liberty to impose the parameters and gives better access for the instrumentation and antennas. The project will support the development of diagnostic methods for characterising RF sheaths and validate and improve theoretical predictions. The cylindrical vacuum vessel has a diameter of 1 m and is 1.1 m long. The plasma is created by an external cylindrical plasma source equipped with a helical antenna that has been designed to excite the m=1 helicon mode. In inductive mode, plasma densities and electron temperatures have been characterised with a planar Langmuir probe as a function of gas pressure and input RF power. A 2D array of RF compensated Langmuir probes and a spectrometer are planned. A single strap RF antenna has been designed; the plasma-facing surface is aligned to the cylindrical plasma to ease the modelling. The probes will allow direct measurements of plasma density profiles in front of the RF antenna, and thus a detailed study of the density modifications induced by RF sheaths, which influences the coupling. The RF antenna frequency has been chosen to study different plasma wave interactions: the accessible plasma density range includes an evanescent and propagative behaviour of slow or fast waves, and allows the study of the effect of the lower hybrid resonance layer.

  12. Vergence and facing patterns in large-scale sheath folds

    NASA Astrophysics Data System (ADS)

    Alsop, G. I.; Holdsworth, R. E.

    1999-10-01

    The careful geometric analysis of minor structural detail elucidates the relationships and evolution of associated large-scale curvilinear hinge geometries, developed during WNW-directed Caledonian thrusting exposed in Neoproterozoic Moine psammites of the Moine Nappe. Reversals in the polarity of structural facing associated with minor folding, mark the position of major sheath folds which parallel transport. Upwardly convex sheaths (closing in the direction of thrust transport) cored by older gneissose basement inliers are termed culminations, whilst those opening in the transport direction (and cored by Moine psammites) are termed depressions. Sheath folds are bisected by transport parallel and foliation normal (culmination/depression) surfaces which separate not only the reversals in facing, but also delineate zones of minor fold hinge obliquity into clockwise and anticlockwise domains relative to the transport direction. The sense of obliquity of minor Z and S folds is thus dependent on position with respect to the surfaces of culmination and depression and not the fold axial surfaces. Surfaces of culmination and depression may be superimposed on original overturned antiformal and synformal folds to produce a variety of dome (culmination on antiform), saddle (depression on antiform), inverted saddle (culmination on synform) and basin (depression on synform) configurations. The curvilinear hinges of minor folds may also be asymmetrical about the transport direction and within the plane of the regional foliation to define patterns of fold hinge-line vergence. Classical concepts of fold limb vergence may thus relate to larger antiformal and synformal hinges, whilst the fold hinge-line vergence defines major curvilinear hinges associated with culminations and depressions. Major sheath folds may therefore be interpreted in terms of both minor fold hinge-line and limb vergence, coupled with fold axis obliquity and reversals in the polarity of structural facing. The

  13. Vanishing of the negative anode sheath in a Hall thruster

    SciTech Connect

    Ahedo, E.; Rus, J.

    2005-08-15

    The transition on a Hall thruster discharge from negative to zero anode sheaths is studied with a macroscopic, stationary model. Since electron drift velocities become of the order of the thermal velocity, inertial effects on electrons must be included in the model. For thrusters with the Hall parameter still large at the anode, these effects appear only in a thin region and bound the electron azimuthal velocity at the anode to values of the order of the thermal velocity. The no-sheath regime is reached when the discharge voltage is decreased and corresponds to a small and nonmonotonic portion of the voltage-current curve. Possible connections of this behavior with experimental results are suggested. Modifications on the discharge characteristics at the regime transition are analyzed. Energy losses at the lateral walls decrease with the discharge voltage, due to the changes on the temperature profile, whereas energy losses at the anode increase only moderately. The thrust efficiency presents a maximum within the negative-sheath regime.

  14. Collector and source sheaths of a finite ion temperature plasma

    SciTech Connect

    Schwager, L.A.; Birdsall, C.K.

    1988-04-13

    The region between a Maxwellian plasma source and an absorbing surface is modeled with an electrostatic particle simulation and with a kinetic plasma-sheath model. In the kinetic model, Poisson's equation and Vlasov equations govern the velocity distribution of the ions and electrons. Our numerical and theoretical results for collector potential and plasma transport agree with the bounded model of Emmert et al., but differ somewhat from those using traditional Bohm sheath analysis. The plasma source injects equal fluxes of half-Maxwellian ions and electrons with specified mass and temperature ratios and is assumed to have a zero electric field. Representing the potential change within a distributed full-Maxwellian source region, the source potential drop depends primarily on temperature ratio and evolves a few Debye lengths from the source to neutralize the injected plasma. The plasma flows to an electrically floating collector where the more familiar electron-repelling collector sheath appears. Profiles of potential, density, drift velocity, temperature, kinetic energy flux, and heat flux are shown from simulation; all compare very well with theory. 24 refs., 7 figs., 1 tab.

  15. Unified Model of the rf Plasma Sheath, Part II

    NASA Astrophysics Data System (ADS)

    Riley, Merle

    1996-10-01

    By developing an approximation to the first integral of the Poisson equation, one can obtain solutions for the current-voltage characteristics of an rf plasma sheath that are valid over the whole range of inertial response of the ions to an imposed rf voltage or current. (M.E.Riley, 1995 GEC, abstract QA5, published in Bull. Am. Phys. Soc., 40, 1587 (1995).) The theory has been shown to adequately reproduce current-voltage characteristics of two extreme cases (M.A. Lieberman, IEEE Trans. Plasma Sci. 16, 638 (1988). A. Metze, D.W. Ernie, and H.J.Oskam, J.Appl.Phys., 60, 3081 (1986).) of ion response. In this work I show the effect of different conventions for connecting the sheath model to the bulk plasma. Modifications of the Mach number and a finite electric field at the Bohm point are natural choices. The differences are examined for a sheath in a high density Ar plasma and are found to be insignificant. A theoretical argument favors the electric field modification. *Work performed at Sandia National Labs and supported by US DoE under contract DE-AC04-94AL85000.

  16. Nonextensivity effect on radio-wave transmission in plasma sheath

    NASA Astrophysics Data System (ADS)

    Mousavi, A.; Esfandiari-Kalejahi, A.; Akbari-Moghanjoughi, M.

    2016-04-01

    In this paper, new theoretical findings on the application of magnetic field in effective transmission of electromagnetic (EM) waves through a plasma sheath around a hypersonic vehicle are reported. The results are obtained by assuming the plasma sheath to consist of nonextensive electrons and thermal ions. The expressions for the electric field and effective collision frequency are derived analytically in the framework of nonextensive statistics. Examination of the reflection, transmission, and absorption coefficients regarding the strength of the ambient magnetic field shows the significance of q-nonextensive parameter effect on these entities. For small values of the magnetic field, the transmission coefficient increases to unity only in the range of - 1 < q < 1 . It is also found that the EM wave transmission through the nonextensive plasma sheath can take place using lower magnetic field strengths in the presence of superthermal electrons compared with that of Maxwellian ones. It is observed that superthermal electrons, with nonextensive parameter, q < 1, play a dominant role in overcoming the radio blackout for hypersonic flights.

  17. Self-consistently simulation of RF sheath boundary condition in BOUT + + framework

    NASA Astrophysics Data System (ADS)

    Gui, Bin; Xu, Xueqiao; Xia, Tianyang

    2015-11-01

    The effect of the RF sheath boundary condition on the edge-localized modes and the turbulent transport is simulated in this work. The work includes two parts. The first part is to calculate the equilibrium radial electric field with RF sheath boundary condition. It is known the thermal sheath or the rectified RF sheath will modify the potential in the SOL region. The modified potential induces addition shear flow in SOL. In this part, the equilibrium radial electric field across the separatrix is calculated by solving the 2D current continuity equation with sheath boundary condition, drifts and viscosity. The second part is applying the sheath boundary condition on the perturbed variables of the six-field two fluid model in BOUT + + framework. The six-field two-fluid model simulates the ELMs and turbulent transport. The sheath boundary condition is applied in this model and it aims to simulate effect of sheath boundary condition on the turbulent transport. It is found the sheath boundary plays as a sink in the plasma and suppresses the local perturbation. Based on this two work, the effect of RF sheath boundary condition on the ELMs and turbulent transport could be self-consistently simulated. Prepared by LLNL under Contract DE-AC52-07NA27344.

  18. Radio-frequency sheath voltages and slow wave electric field spatial structure

    SciTech Connect

    Colas, Laurent Lu, Ling-Feng; Křivská, Alena; Jacquot, Jonathan

    2015-12-10

    We investigate theoretically how sheath radio-frequency (RF) oscillations relate to the spatial structure of the RF parallel electric field emitted by Ion Cyclotron (IC) wave launchers, using a simple model of Slow Wave (SW) evanescence coupled with Direct Current (DC) plasma biasing via sheath boundary conditions in a plasma-filled 2-dimensional (parallel, radial) rectangle. Within a “wide sheaths” asymptotic regime, valid for large-amplitude near RF fields, our model becomes partly linear: the sheath oscillating voltage at open field line boundaries is a linear combination of elementary contributions by every source point of the radiated RF field map. These individual contributions are all the more intense as the SW emission point is toroidally nearer to the sheath walls. A limit formula is given for a source infinitely close to the sheaths. The decay of sheath RF voltages with the sheath/source parallel distance is quantified as a function of two characteristic SW evanescence lengths. Decay lengths are smaller than antenna parallel extensions. The sheath RF voltages at an IC antenna side limiter are therefore mainly sensitive to SW emission near this limiter, as recent observations suggest. Toroidal proximity effects could also explain why sheath oscillations persist with antisymmetric strap toroidal phasing, despite the parallel anti-symmetry of the radiated field map. They could also justify current attempts at reducing the RF fields induced near antenna boxes to attenuate sheath oscillations in their vicinity.

  19. Characteristics of wall sheath and secondary electron emission under different electron temperatures in a Hall thruster

    NASA Astrophysics Data System (ADS)

    Duan, Ping; Qin, Hai-Juan; Zhou, Xin-Wei; Cao, An-Ning; Chen, Long; Gao, Hong

    2014-07-01

    In this paper, a two-dimensional physical model is established in a Hall thruster sheath region to investigate the influences of the electron temperature and the propellant on the sheath potential drop and the secondary electron emission in the Hall thruster, by the particle-in-cell (PIC) method. The numerical results show that when the electron temperature is relatively low, the change of sheath potential drop is relatively large, the surface potential maintains a stable value and the stability of the sheath is good. When the electron temperature is relatively high, the surface potential maintains a persistent oscillation, and the stability of the sheath reduces. As the electron temperature increases, the secondary electron emission coefficient on the wall increases. For three kinds of propellants (Ar, Kr, and Xe), as the ion mass increases the sheath potentials and the secondary electron emission coefficients reduce in sequence.

  20. Model and particle-in-cell simulation of ion energy distribution in collisionless sheath

    SciTech Connect

    Zhou, Zhuwen; Kong, Bo; Luo, Yuee; Chen, Deliang; Wang, Yuansheng

    2015-06-15

    In this paper, we propose a self-consistent theoretical model, which is described by the ion energy distributions (IEDs) in collisionless sheaths, and the analytical results for different combined dc/radio frequency (rf) capacitive coupled plasma discharge cases, including sheath voltage errors analysis, are compared with the results of numerical simulations using a one-dimensional plane-parallel particle-in-cell (PIC) simulation. The IEDs in collisionless sheaths are performed on combination of dc/rf voltage sources electrodes discharge using argon as the process gas. The incident ions on the grounded electrode are separated, according to their different radio frequencies, and dc voltages on a separated electrode, the IEDs, and widths of energy in sheath and the plasma sheath thickness are discussed. The IEDs, the IED widths, and sheath voltages by the theoretical model are investigated and show good agreement with PIC simulations.

  1. The Relation of Carbon Dioxide Compensation and Chlorenchymatous Vascular Bundle Sheaths in Leaves of Dicots

    PubMed Central

    Crookston, R. Kent; Moss, Dale N.

    1970-01-01

    Low CO2 compensation points have been found to be associated with several unusual characteristics related to photosynthesis. One such characteristic is a prominent, chlorenchymatous vascular bundle sheath in the leaves. It has been suggested that the presence of this sheath in dicotyledons can serve as a means of detecting low CO2-compensating species. We collected 88 dicotyledon species from 22 families reported to have chlorenchymatous sheaths. Of the 88, only three, Tribulus terrestris, L., Boerhaavia paniculata, L. C. Rich, and Trianthema portulacastrum L., had low CO2 compensation points. Cross sections of the leaves of the other species revealed that they did have chlorenchymatous vascular bundle sheaths. However, these sheath cells contained chloroplasts which were not specialized for starch formation as were the bundle sheath chloroplasts of the low CO2-compensating species. Images PMID:16657506

  2. Dialysis catheter fibrin sheath stripping: a useful technique after failed catheter exchange.

    PubMed

    Mohamad Ali, Af; Uhwut, E; Liew, Sk

    2012-01-01

    Fibrin sheath formation around long-term haemodialysis catheter is a common cause of failed dialysis access. Treatment options include pharmacological and mechanical methods. This paper reports a case of failed dialysis access due to fibrin sheath encasement. Pharmacologic thrombolysis, mechanical disruption using guide wire and catheter exchange had failed to address the issue. Eventually, fibrin sheath stripping using the loop snare technique was able to successfully restore the catheter function. PMID:22970064

  3. Formation and stability of polarization sheaths of a cross-field beam

    NASA Technical Reports Server (NTRS)

    Cai, Dong S.; Buneman, Oscar

    1992-01-01

    A simple description is presented for a pure ion sheath formed on one side and a pure electron sheath formed on the other side of a neutral plasma beam. Both the ion and the electron sheath are found to be one-dimensionally stable and two-dimensionally unstable in a mode known as magnetron, slipping stream, and diocotron. This mode connects with the Kelvin-Helmholtz instability in neutral matter. The analytical results are confirmed both qualitatively and quantitatively by numerical simulations. The simulations help define the linear behavior of the long-wave instability generated in the electron (or ion) sheath, including a strong shear.

  4. Development of a core sheath process for production of oxide fibers

    NASA Technical Reports Server (NTRS)

    Freske, S.

    1972-01-01

    Improvements were sought in an oxide fiber of a core sheath configuration intended for structural applications at 2000 F (1093 C). Discontinuities in the core were eliminated by using core materials other than pure alumina, and continuous core sheath fibers were produced. In the case of some core materials, the continuous sections were sufficiently long for applications in short fiber composites. Creep at 2000 F (1093 C) was found to be due, in most cases, to breaks in the core, allowing the glass sheath to creep. Evidence was obtained indicating that a closer match between the thermal expansion coefficient of the sheath and the core would greatly improve the strength.

  5. A Cytochemical Study of Extracellular Sheaths Associated with Rigidoporus lignosus during Wood Decay

    PubMed Central

    Nicole, M.; Chamberland, H.; Rioux, D.; Lecours, N.; Rio, B.; Geiger, J. P.; Ouellette, G. B.

    1993-01-01

    An ultrastructural and cytochemical investigation of the development of Rigidoporus lignosus, a white-rot fungus inoculated into wood blocks, was carried out to gain better insight into the structure and role of the extracellular sheaths produced by this fungus during wood degradation. Fungal sheaths had a dense or loose fibrillar appearance and were differentiated from the fungal cell wall early after wood inoculation. Close association between extracellular fibrils and wood cell walls was observed at both early and advanced stages of wood alteration. Fungal sheaths were often seen deep in host cell walls, sometimes enclosing residual wood fragments. Specific gold probes were used to investigate the chemical nature of R. lignosus sheaths. While labeling of chitin, pectin, β-1,4- and β-1,3-glucans, β-glucosides, galactosamine, mannose, sialic acid, RNA, fucose, and fimbrial proteins over fungal sheaths did not succeed, galactose residues and laccase (a fungal phenoloxidase) were found to be present. The positive reaction of sheaths with the PATAg test indicates that polysaccharides such as β-1,6-glucans are important components. Our data suggest that extracellular sheaths produced by R. lignosus during host cell colonization play an important role in wood degradation. Transportation of lignin-degrading enzymes by extracellular fibrils indicates that alteration of plant polymers may occur within fungal sheaths. It is also proposed that R. lignosus sheaths may be involved in recognition mechanisms in fungal cell-wood surface interactions. Images PMID:16349017

  6. The dust motion inside the magnetized sheath - The effect of drag forces

    SciTech Connect

    Pandey, B. P.; Samarian, A.; Vladimirov, S. V.

    2010-08-15

    The isolated charged dust inside the magnetized plasma sheath moves under the influence of the electron and ion drag force and the sheath electrostatic field. The charge on the dust is a function of its radius as well as the value of the ambient sheath potential. It is shown that the charge on the dust determines its trajectory and dust performs the spiraling motion inside the sheath. The location of the turning spiral is determined by the number of negative charge on the dust, which in turn is a function of the dust radius. The back and forth spiraling motion finally causes the dust to move in a small, narrow region of the sheath. For a bigger dust particle, the dust moves closer to the sheath presheath boundary suggesting that the bigger grains, owing to the strong repulsion between the wall and dust, will be unable to travel inside the sheath. Only small, micron-sized grains can travel closer to the wall before repulsion pushes it back toward the plasma-sheath boundary. The temporal behavior of the spiraling dust motion appears like a damped harmonic oscillation, suggesting that the plasma drag force causes dissipation of the electrostatic energy. However, after initial damping, the grain keeps oscillating although with much smaller amplitude. The possible application of the present results to the ongoing sheath experiments is discussed.

  7. The modeling and simulation of plasma sheath effect on GNSS system

    NASA Astrophysics Data System (ADS)

    Song, Zhongguo; Liu, Jiangfan; Du, Yongxing; Xi, Xiaoli

    2015-11-01

    Plasma sheath can potentially degrade global navigation satellite system (GNSS) through signal attenuation as well as phase noise when a hypersonic vehicle reenters the Earth's atmosphere. Modeling and simulation method of GNSS system disturbed by plasma sheath is introduced in this paper by means of electromagnetic wave propagation theory combined with the satellite signal simulation technique. The transmission function of the plasma sheath with stratified model is derived utilizing scattering matrix method. The effects of the plasma sheath on GPS signal reception and positioning performance are examined. Experimental results are presented and discussed, partly supporting the validity of the analytical method proposed.

  8. Sheath and presheath in ion-ion plasmas via particle-in-cell simulation

    SciTech Connect

    Meige, A.; Leray, G.; Raimbault, J.-L.; Chabert, P.

    2008-02-11

    A full particle-in-cell simulation is developed to investigate electron-free plasmas constituted of positive and negative ions under the influence of a dc bias voltage. It is shown that high-voltage sheaths following the classical Child-law sheaths form within a few microseconds (which corresponds to the ion transit time) after the dc voltage is applied. It is also shown that there exists the equivalent of a Bohm criterion where a presheath accelerates the ions collected at one of the electrodes up to the sound speed before they enter the sheath. From an applied perspective, this leads to smaller sheaths than one would expect.

  9. Thrombus on Indwelling Central Venous Catheters: The Histopathology of 'Fibrin Sheaths'

    SciTech Connect

    Suojanen, James Norman; Brophy, David Paul; Nasser, Imad

    2000-03-15

    Purpose: Central venous catheters (CVC) may fail for many reasons, though 'fibrin sheaths' blocking catheter ports are usually implicated. We examined the sheaths removed from dialysis catheters to determine their histopathology.Methods: Ten catheter strippings were performed and the removed material was studied grossly and microscopically.Results: The histologic specimens showed thrombus both with and without a proteinaceous sheath.Conclusion: Dialysis catheters fail because of thrombus formation. This can occur in either the absence or presence of a protein coating on the catheter, the so-called 'fibrin sheath.'.

  10. The spatiotemporal oscillation characteristics of the dielectric wall sheath in stationary plasma thrusters

    SciTech Connect

    Zhang Fengkui; Yu Daren; Ding Yongjie; Li Hong

    2011-03-14

    A two-dimensional particle in cell model is used to simulate the sheath oscillation in stationary plasma thrusters. The embedded secondary electron emission (SEE) submodel is based on that of Morozov but improved by considering the electron elastic reflection effect. The simulation results show that when the SEE coefficient is smaller than one due to the relative low electron temperature, one-dimensional static sheath can be found; as the electron temperature increase, the SEE coefficient approaches to one and temporal oscillation sheath appears; when the electron temperature increases so high that the SEE coefficient is beyond one, the sheath oscillates not only in time but also in space.

  11. Flexor Tendon Sheath Ganglions: Results of Surgical Excision

    PubMed Central

    Spencer, Edwin E.

    2007-01-01

    The purpose of our study was to review the clinical features and determine the results following surgical excision of a flexor tendon sheath ganglion. A retrospective analysis of 24 consecutive patients (25 ganglions) who underwent excision of a painful flexor tendon sheath ganglion by the same surgeon was performed. The patient’s medical and operative records were reviewed. Each patient was invited to return for an evaluation, which consisted of a clinical interview, completion of a questionnaire, and physical examination. Those patients that were unable to return underwent a detailed telephone interview. Sixteen patients returned for a clinical evaluation, while eight patients underwent a telephone interview. There were 15 women and nine men, with an average age of 43 years (range, 21–68 years). The dominant hand was involved in 15 patients. The long finger was most commonly involved (11 cases). The ganglion arose from the A1 pulley in 13 cases, between the A1 and A2 pulleys in three cases, and from the A2 pulley in nine cases. At an average follow-up of 18.5 months (range, 5–38 months), all of the patients were satisfied with their final result. No patient developed a recurrence and all returned to their previous functional level. There were two minor complications that resolved uneventfully; one patient experienced mild incisional tenderness, while an additional patient experienced transient digital nerve paresthesias. We conclude that surgical excision is a simple, safe, and effective method for treating a painful ganglion of the digital flexor tendon sheath. PMID:18780066

  12. Genetic Analysis of Rough Sheath1 Developmental Mutants of Maize

    PubMed Central

    Becraft, P. W.; Freeling, M.

    1994-01-01

    Maize Rough sheath1 (Rs1) mutants are dominant and cause a proliferation of sheath-like tissue at the base of the blade and throughout the ligular region. They also cause ligule displacement, a chaotic pattern of vasculature and abnormal cellular structure of vascular bundles. The affected region of Rs1-O leaves displays genetic and morphological attributes of both sheath and auricle, suggesting an overlap of these genetic programs. The rs1 locus maps approximately 26 map units distal to opaque2 (o2) on chromosome 7S, defining a new distal-most locus on the genetic map. Three mutant alleles, Rs1-O, Rs1-1025 and Rs1-Z, all display similar phenotypes. The mutations are completely dominant and the Rs1-O phenotype is not affected by dosage of the chromosome arm carrying the rs1(+) allele, indicating that these alleles are neomorphic. Analysis of genetic mosaics showed that the Rs1-O phenotype is non-cell-autonomous, suggesting that intercellular signals convey the phenotype. Rs1 mutant phenotypes are affected by modifiers present in particular genetic backgrounds. An enhancer of Rs1-O was identified; segregation data imply a single recessive gene, ers1. Rs1 mutants were also found to enhance the expression of unlinked rs2 and Rs4 mutants, suggesting that these mutations affect similar developmental processes. We discuss the phenotypic and genetic similarities between Rs1 and Knotted1 (Kn1) mutants that led to the identification of rs1 as a kn1-like homeobox gene (unpublished data). PMID:8138166

  13. Low-current medium-pressure RF discharge with electron photoemission in the electrode sheath and penetration of the sheath electrons into the discharge column

    SciTech Connect

    Baranov, I. Ya.; Koptev, A. V.

    2007-12-15

    A model is developed for simulating a low-current moderate-pressure RF discharge with allowance for such characteristic discharge properties as the existence of two sheaths near both electrodes throughout the RF field period; the formation of an electron cloud at the sheath boundary that periodically fills the sheath and leaves it, depending on the phase of the applied RF voltage; the production by the sheath electrons of metastable gas particles that interact with the cloud electrons during subsequent field periods, followed by the excitation of metastable states to the emitting levels; the formation of a sheath in a low-current RF discharge due to the overlap of the secondary electron avalanches triggered by electron photoemission from the electrode surface; and the conditions under which the sheath electrons penetrate into the positive column and accumulate there, which makes, thereby making a low-current RF discharge similar to a non-self-sustained discharge. The parameters of the sheath in a low-current RF discharge are determined by the conditions under which the electron photoemission current from the electrode surface in the sheath is self-sustaining and, like the parameters of the positive discharge column, depend on the sort of gas, the gas pressure, the frequency of the applied RF field, and the interelectrode distance. The results of calculating the parameters of the sheath and column of a low-current RF discharge for nitrogen and helium at different pressures, as well as for different field frequencies and interelectrode distances, are presented and are compared with the experimental data.

  14. Malignant Peripheral Nerve Sheath Tumour: CT and MRI Findings.

    PubMed

    Sperandio, Massimiliano; Di Poce, Isabelle; Ricci, Aurora; Di Trapano, Roberta; Costanzo, Elisa; Di Cello, Pierfrancesco; Pelle, Fabio; Izzo, Luciano; Simonetti, Giovanni

    2013-01-01

    Malignant peripheral nerve sheath tumour (MPNST) is extremely rare malignancy in the general population, occurring more frequently in patients with Neurofibromatosis type 1 (NF1). In the literature five cases of MPNST arising from the parapharyngeal space (PPS) in patients without neurofibromatosis have been reported. We report imaging techniques in a patient with MPNST in the PPS, who had neither a family history nor sign of NF1. Computed tomography (CT) scan and magnetic resonance imaging (MRI) were performed for a correct therapeutic planning. CT and MRI findings were correlated with hystopathological diagnosis. PMID:23970990

  15. Cystic change in primary paediatric optic nerve sheath meningioma.

    PubMed

    Narayan, Daniel; Rajak, Saul; Patel, Sandy; Selva, Dinesh

    2016-08-01

    Primary optic nerve sheath meningiomas (PONSM) are rare in children. Cystic meningiomas are an uncommon subgroup of meningiomas. We report a case of paediatric PONSM managed using observation alone that underwent cystic change and radiological regression. A 5-year-old girl presented with visual impairment and proptosis. Magnetic resonance (MR) imaging demonstrated a PONSM. The patient was left untreated and followed up with regular MR imaging. Repeat imaging at 16 years of age showed the tumour had started to develop cystic change. Repeat imaging at 21 years of age showed the tumour had decreased in size. PMID:27310300

  16. Dust Particles Alignments and Transitions in a Plasma Sheath

    SciTech Connect

    Stokes, J. D. E.; Samarian, A. A.; Vladimirov, S. V.

    2008-09-07

    The alignments and transitions of two dust particles in a plasma sheath have been investigated. It is shown that the Hamiltonian description of a non-Hamiltonian system can be used to predict qualitative features of possible equilibria in a variety of confinement potentials and can provide useful plasma diagnostics. The results compare favorably with simulation and are used to create new experimental hypotheses. In particular, the symmetry breaking transition of the particles as they leave the horizontal plane admits a Hamiltonian description which is used to elucidate the wake parameter.

  17. Mechanical Thrombectomy of Iliocaval Thrombosis Using a Protective Expandable Sheath

    SciTech Connect

    Truong, Tri H.; Spuentrup, Elmar; Staatz, Gundula; Wildberger, Joachim E.; Schmitz-Rode, Thomas; Nolte-Ernsting, Claus C.A.; Guenther, Rolf W.; Haage, Patrick

    2004-09-15

    We report a case of successful percutaneous treatment of a subacute ilio-caval venous thrombosis in a 64-year-old female patient by using a novel combination of a rotatory fragmentation device (percutaneous thrombectomy device: PTD) and large wire basket (temporary Guenther basket filter) under temporary caval filter protection using an expandable sheath. Because the patient had multiple myeloma with increased risk for contrast media-induced renal failure, the therapeutic angiographic procedure was performed without iodinated contrast medium. Non-contrast-enhanced MR venography (high-resolution True FISP) confirmed the effective thrombus removal by the percutaneous mechanical thrombectomy procedure.

  18. Microparticles deep in the plasma sheath: Coulomb 'explosion'

    SciTech Connect

    Antonova, T.; Du, C.-R.; Ivlev, A. V.; Hou, L.-J.; Thomas, H. M.; Morfill, G. E.; Annaratone, B. M.

    2012-09-15

    A cloud of microparticles was trapped deep in the sheath of a radio-frequency (rf) discharge, very close to the lower (grounded) electrode of the plasma chamber. This was achieved by employing a specifically designed rf-driven segment integrated in the lower electrode, which provided an additional confinement compressing the cloud to a very high density. After switching the rf-driven segment off, the cloud 'exploded' due to mutual interparticle repulsion. By combining a simple theoretical model with different numerical simulation methods, some basic properties of complex plasmas in this highly non-equilibrium regime were determined.

  19. Intrarenal pressure and irrigation flow with commonly used ureteric access sheaths and instruments

    PubMed Central

    Wright, Anna; Williams, Kevin; Somani, Bhaskar

    2015-01-01

    Introduction Flexible ureterorenoscopy is becoming a first-line treatment for many intrarenal stones. Ureteric access sheaths are commonly used to aid access, stone removal and reduce intrarenal pressure. We evaluated the effects of two commonly used access sheaths on irrigation flow and intrarenal pressure during flexible ureterorenoscopy. We measured the effect of scope instrumentation on flow and pressure. Material and methods We utilized a 10/12F and 12/14F, 35 cm Re-Trace™ access sheath with a FlexX2 scope in a cadaveric porcine kidney. We evaluated the effect of four Nitinol baskets (1.3F, 1.5F, 1.9F, 2.2F), three different 200 µm laser fibres and a hand-held pump. Measurements of irrigation flow and intrarenal pressure were recorded and compared between the different sized access sheaths. Results Flow rates varied widely between access sheaths. Without instrumentation, mean flow was 17 mls/min (10/12F access sheath), versus 33 mls/min (12/14F sheath) (p <0.0001). Increasing basket size produced a gradual reduction in flow and pressure in both access sheaths. Reassuringly, pressures were low overall (<40 cm H2O). Pressures were significantly reduced when using the larger 12/14F sheath, with and without all instrumentations (p <0.0001). Hand-held pump devices have a marked effect on flow and pressure in both sheaths; with pressures rising up to 121 cm H2O with a 10/12F sheath, versus 29 cm H2O (12/14F) (p <0.0001). Conclusions A 12/14F access sheath offered significantly improved irrigation whilst maintaining significantly lower intrarenal pressure, when compared to a 10/12F access sheath in a cadaveric porcine model. Scope instrumentation affects irrigation flow and pressure in both sized sheaths. Furthermore, there should be caution with hand-held pump devices, especially with smaller sized sheaths, as intrarenal pressure can be very high. PMID:26855796

  20. Experimental studies of anode sheath phenomena in a hall thruster.

    SciTech Connect

    Dorf, L. A.; Fisch, N. J.; Raitses, Yevgeny F.

    2004-01-01

    Both electron-repelling (negative anode fall) and electron-attracting (positive anode fall) anode sheaths in a Hall thruster were identified experimentally by performing accurate, non-disturbing near-anode measurements with biased and emissive probes. An interesting new phenomenon revealed by the probe measurements is that the anode fall changes from positive to negative upon removal of the dielectric coating, which appears on the anode surface during the course of Hall thruster operation. Probe measurements in a Hall thruster with three different magnetic field configurations show that an anode fall at the clean anode is a function of the radial magnetic field profile inside the channel. A positive anode fall formation mechanism suggested in this work is that: (1) when the anode front surface is coated with dielectric, a discharge current closes to the anode at the surfaces that remain conductive, (2) a total thermal electron current toward the conductive area is significantly smaller than the discharge current, therefore an additional electron flux needs to be attracted toward the conductive surfaces by the electronattracting sheath that appears at these surfaces.

  1. Evaluation of Risk Factors for Rectus Sheath Hematoma.

    PubMed

    Sheth, Heena S; Kumar, Rohit; DiNella, Jeannine; Janov, Cheryl; Kaldas, Hoda; Smith, Roy E

    2016-04-01

    Rectus sheath hematoma (RSH) develops due to rupture of epigastric arteries or the rectus muscle. Although RSH incidence rate is low, it poses a significant diagnostic dilemma. We evaluated the risk factors for RSH, its presentation, management, and outcomes for 115 patients hospitalized with confirmed RSH by computed tomography scan between January 2005 and June 2009. More than three-fourth (77.4%) of the patients were on anticoagulation therapy, 58.3% patients had chronic kidney disease (CKD) stage ≥3, 51.3% had abdominal injections, 41.7% were on steroids/immunosuppressant therapy, 37.4% had abdominal surgery/trauma, 33.9% had cough, femoral puncture was performed in 31.3% of patients, and 29.5% were on antiplatelet therapy. Rectus sheath hematoma was not an attributable cause in any of the 17 deaths. Mortality was significantly higher in patients with CKD stage ≥3 (P = .03) or who required transfusion (P = .007). Better understanding of RSH risk factors will facilitate early diagnoses and improve management. PMID:25294636

  2. Measure Guideline: Guidance on Taped Insulating Sheathing Drainage Planes

    SciTech Connect

    Grin, A.; Lstiburek, J.

    2014-09-01

    This guide provides information and recommendations to the following groups: insulation contractors; general contractors; builders; home remodelers; mechanical contractors; and homeowners, as a guide to the work that needs to be done. The order of work completed during home construction and retrofit improvements is important. Health and safety issues must be addressed first and are more important than durability issues. And durability issues are more important than saving energy. Not all techniques can apply to all houses. Special conditions will require special action. Some builders or homeowners will wish to do more than the important but basic retrofit strategies outlined by this guide. The following are best practice and product recommendations from the interviewed contractors and homebuilders who collectively have a vast amount of experience. Three significant items were discussed with the group which are required to make taped insulating sheathing a simple, long term, and durable drainage plane: 1. Horizontal joints should be limited or eliminated wherever possible; 2. Where a horizontal joint exists use superior materials; 3. Frequent installation inspection and regular trade training are required to maintain proper installation. Section 5 of this measure guideline contains the detailed construction procedure for the three recommended methods to effectively seal the joints in exterior insulating sheathing to create a simple, long term, and durable drainage plane.

  3. Isolation, Cultural Maintenance, and Taxonomy of a Sheath-Forming Strain of Leptothrix discophora and Characterization of Manganese-Oxidizing Activity Associated with the Sheath

    PubMed Central

    Emerson, David; Ghiorse, William C.

    1992-01-01

    Leptothrix discophora SP-6 was isolated from the outflow reservoir of an artificial iron seep. Its sheathforming phenotype was maintained by slow growth in a mineral salts-vitamin-pyruvate medium under minimal aeration at 20 to 25°C. A sheathless variant, SP-6(sl), was isolated from smooth colonies that appeared on spread plates after rapid growth of SP-6 in well-aerated cultures. SP-6 and SP-6(sl) are closely related but not identical to the previously studied sheathless strain SS-1 (ATCC 43182). Increasing Mn2+ concentrations in the growth medium of SP-6 increased the phase density of the sheath, indicating increased Mn oxide deposition in the sheath. Electron microscopy of cultures grown without added Mn2+ revealed that the sheath consisted of a well-defined inner layer, 30 to 100 nm thick, and a diffuse outer capsular layer of variable thickness. Mn oxides were identified in the sheath by their characteristic ultrastructure, electron density, and X-ray-dispersive energy spectra. In heavily encrusted sheaths, the Mn oxides were evenly distributed in both layers of the sheath. Sheathed cells retained more Mn-oxidizing activity than did sheathless cells after washing with distilled, deionized water; the sheath retained some of its activity after an EDTA-lysozyme-detergent treatment which removed the cells. An ultrafiltration-dialysis procedure significantly increased the recovery of activity from spent media of SP-6 over that reported previously for SS-1 (L.F. Adams and W.C. Ghiorse, J. Bacteriol. 169:1279-1285, 1987). A 108-kDa Mn-oxidizing protein was identified in concentrated spent media of SP-6 and SP-6(sl), and the activity of the concentrates showed stability in detergents comparable to that of SS-1 and patterns of heat inactivation and chemical inhibition similar to those of SS-1. Images PMID:16348826

  4. Isolation, Cultural Maintenance, and Taxonomy of a Sheath-Forming Strain of Leptothrix discophora and Characterization of Manganese-Oxidizing Activity Associated with the Sheath.

    PubMed

    Emerson, D; Ghiorse, W C

    1992-12-01

    Leptothrix discophora SP-6 was isolated from the outflow reservoir of an artificial iron seep. Its sheathforming phenotype was maintained by slow growth in a mineral salts-vitamin-pyruvate medium under minimal aeration at 20 to 25 degrees C. A sheathless variant, SP-6(sl), was isolated from smooth colonies that appeared on spread plates after rapid growth of SP-6 in well-aerated cultures. SP-6 and SP-6(sl) are closely related but not identical to the previously studied sheathless strain SS-1 (ATCC 43182). Increasing Mn concentrations in the growth medium of SP-6 increased the phase density of the sheath, indicating increased Mn oxide deposition in the sheath. Electron microscopy of cultures grown without added Mn revealed that the sheath consisted of a well-defined inner layer, 30 to 100 nm thick, and a diffuse outer capsular layer of variable thickness. Mn oxides were identified in the sheath by their characteristic ultrastructure, electron density, and X-ray-dispersive energy spectra. In heavily encrusted sheaths, the Mn oxides were evenly distributed in both layers of the sheath. Sheathed cells retained more Mn-oxidizing activity than did sheathless cells after washing with distilled, deionized water; the sheath retained some of its activity after an EDTA-lysozyme-detergent treatment which removed the cells. An ultrafiltration-dialysis procedure significantly increased the recovery of activity from spent media of SP-6 over that reported previously for SS-1 (L.F. Adams and W.C. Ghiorse, J. Bacteriol. 169:1279-1285, 1987). A 108-kDa Mn-oxidizing protein was identified in concentrated spent media of SP-6 and SP-6(sl), and the activity of the concentrates showed stability in detergents comparable to that of SS-1 and patterns of heat inactivation and chemical inhibition similar to those of SS-1. PMID:16348826

  5. Comparison of sheath thickness obtained from the theories of ion correction in the floating potential

    NASA Astrophysics Data System (ADS)

    Han, Hyeong Sik; Hwang, Kwang Tae; Choe, Ik Jin; Chung, Chin Wook

    2009-10-01

    In the cold plasmas, when the cylindrical probe is used to measure the ion density, an expansion of the sheath thickness related to the sheath voltage increases the ion current. The expansion of the sheath thickness results in an incorrect measurement of ion current. To measure ion density correctly, the sheath thickness should be considered. In the collisionless sheath, the sheath thickness can be calculated by the Child- Langmuir (CL) theory or the Allen-Boyd-Reynolds(ABR) theory. We measured the sheath thicknesses using the floating harmonics method [1] and the cut-off method by the microwave [2], and the results compared with the CL theory [3] and ABR theory [4] in the floating potential. The sheath thicknesses obtained from the ABR theory were in good agreement with the experimental results. [4pt] [1] M. H. Lee, S. H. Jang and C. W. Chung, J. Appl. Phys., 101, 033305 (2007)[0pt] [2] J.H. Kim, S.C. Choi, Y.H. Shin, and K. H. Chung, Rev. Sci. Instrum. 75, 2706 (2004)[0pt] [3] FF Chen, JD Evans, D Arnush, Phys. Plasmas 9, 1449 (2002)[0pt] [4] F. F. Chen and D. Arnush, Phys. Plasmas 8, 5051 (2001)

  6. Plasma-wall interaction in an electrostatic sheath of plasma containing a monoenergetic electron beam

    NASA Astrophysics Data System (ADS)

    Ou, Jing; Zhao, Xiaoyun; Gan, Chunyun

    2016-04-01

    The plasma-wall interaction in the presence of a monoenergetic electron beam has been studied by taking into account the self-consistency among plasma transport in a collisionless electrostatic sheath, deposited energy flux at the wall and material thermal response for carbon and tungsten as wall materials. The variations of the potential drop across the sheath, ion velocity at the sheath edge, and surface temperature of material as a function of electron beam flux are explored in the presence of the electron emission. It is found that when electron beam does not dominate the sheath, potential drop across the sheath depends strongly on the material properties due to the impact of electron emission while the surface temperature of material shows monotonic variation. In the case of carbon wall, the electron beam may dominate the sheath at a certain electron beam concentration or energy. Under this circumstance, both the potential drop across the sheath and surface temperature of material demonstrate the sharp increasing transition. The development of local hot spot on the plasma facing material is caused by the enhanced ion energy flux instead of the electron beam energy flux. If the electron emission is not taken into account, as a smaller electron beam flux, both the potential drop across the sheath and surface temperature of material display the significant change and then it may be easier to develop for the local hot spot on the plasma facing material.

  7. Confirming QTLs and finding additional loci responsible for resistance to rice sheath blight disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Rice sheath blight disease (Rhizoctonia solani AG1-1AKühn) is one of the most destructive rice diseases worldwide. Utilization of host resistance is the most economical and environmentally sound strategy in managing sheath blight (ShB). Ten ShB-QTLs were previously mapped in a LJRIL population using...

  8. Release of four new breeding lines having resistance to blast and sheath blight diseases

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight and rice blast diseases are serious threats to rice production worldwide. High-yielding cultural management practices, such as high nitrogen application and high plant populations, encourage development of these diseases. Complete resistance to sheath blight has not been identified, al...

  9. Effect of two-temperature electrons distribution on an electrostatic plasma sheath

    NASA Astrophysics Data System (ADS)

    Ou, Jing; Xiang, Nong; Gan, Chunyun; Yang, Jinhong

    2013-06-01

    A magnetized collisionless plasma sheath containing two-temperature electrons is studied using a one-dimensional model in which the low-temperature electrons are described by Maxwellian distribution (MD) and high-temperature electrons are described by truncated Maxwellian distribution (TMD). Based on the ion wave approach, a modified sheath criterion including effect of TMD caused by high-temperature electrons energy above the sheath potential energy is established theoretically. The model is also used to investigate numerically the sheath structure and energy flux to the wall for plasmas parameters of an open divertor tokamak-like. Our results show that the profiles of the sheath potential, two-temperature electrons and ions densities, high-temperature electrons and ions velocities as well as the energy flux to the wall depend on the high-temperature electrons concentration, temperature, and velocity distribution function associated with sheath potential. In addition, the results obtained in the high-temperature electrons with TMD as well as with MD sheaths are compared for the different sheath potential.

  10. Development and characterization of RiceCAP QTL mapping population for sheath blight resistance

    Technology Transfer Automated Retrieval System (TEKTRAN)

    RiceCAP is a USDA CSREES funded project that has as one of its main objectives developing genetic markers associated with sheath blight resistance. Sheath blight, caused by Rhizoctonia solani, is an important disease of rice in the southern US. Tolerance to the disease is quantitatively inherited an...

  11. Analytical expression for the sheath edge around wedge-shaped cathodes

    NASA Astrophysics Data System (ADS)

    Sheridan, T. E.

    2008-03-01

    The sheath is the boundary layer separating a quasi-neutral plasma from a material electrode. Understanding the sheath is important for numerous applications, including plasma-based ion implantation, plasma etching of semiconductors, plasma assisted electrostatic cleaning, and Langmuir probes. In a 1D planar geometry, the Child-Langmuir (CL) law describes the sheath when the bias on a negative electrode, i.e., a cathode, is much greater than the electron temperature. In this case, the sheath width s is an eigenvalue of the problem. In 2D, the sheath edge is an unknown line (an ``eigen-boundary") which is determined by a set of coupled, nonlinear, partial differential equations. I have found an expression for the sheath edge around a 2D wedge-shaped cathode with included angle θw. In polar coordinates (r,θ), the sheath edge is a solution of r(aθ)=as where s is the planar sheath width far from the corner and θw=2π- π/a, so that a=1/2 gives a knife edge, while a=2/3 gives a square corner. This result is verified by comparison with the numerical solutions of Watterson [P. A. Watterson, J. Phys. D 22, 1300 (1989)].

  12. Dusty Plasma Modeling of the Fusion Reactor Sheath Including Collisional-Radiative Effects

    SciTech Connect

    Dezairi, Aouatif; Samir, Mhamed; Eddahby, Mohamed; Saifaoui, Dennoun; Katsonis, Konstantinos; Berenguer, Chloe

    2008-09-07

    The structure and the behavior of the sheath in Tokamak collisional plasmas has been studied. The sheath is modeled taking into account the presence of the dust{sup 2} and the effects of the charged particle collisions and radiative processes. The latter may allow for optical diagnostics of the plasma.

  13. Investigation on measurement of effective sheath width using a cutoff probe

    NASA Astrophysics Data System (ADS)

    Kim, Jung-Hyung; Kim, Dae-Woong; You, Shin-Jae

    2015-09-01

    The plasma density is the key parameter showing electric plasma property as well as processing rate. Therefore, various diagnostic methods have been developed and researched for measuring the absolute plasma density. One of them, cutoff probe, has been developed for more accurate measurement of the plasma density. The cutoff probe is the promising diagnostics method having diagnostic advantages: high accuracy in measured plasma density, simple assumption in measurement process, and readily use and interpretation of results for diagnostics. The sheath is also an important parameter in plasma researches and applications. In this presentation, we introduce measurement method of the effective sheath width using equivalent circuit model of S21 phase spectrum of the cutoff probe. The reliability of this method was verified by investigation of the FDTD simulation and comparative experiment with calculated Child-Langmuir law sheath width from Langmuir probe data. The results show that measured sheath width has an acceptable error when it was compared with input sheath width in the FDTD simulation. Furthermore, the measured sheath width was found to be in good agreement with the floated sheath width calculated from the Child-Langmuir sheath law.

  14. Retrieval of a detached transseptal sheath tip from a right pulmonary artery branch following catheter ablation.

    PubMed

    Schricker, Amir A; Feld, Gregory K; Tsimikas, Sotirios

    2015-11-15

    Transseptal introducer sheaths are being used with increasing frequency for left-sided arrhythmia ablations and structural heart disease interventions. Sheath tip detachment and embolization is an uncommon but known complication, and several sheaths have been recalled due to such complications. We report a unique case of a fractured transseptal sheath tip that embolized to a branch of the right pulmonary artery in a patient who had undergone ablation of a left-sided atypical atrial flutter. During final removal of one of the two long 8.5-French SL1 transseptal sheaths used routinely as part of the ablation, the radiopaque tip of the sheath fractured and first embolized to the right atrium and subsequently to a secondary right pulmonary artery branch. Using techniques derived from percutaneous interventional approaches, including a multipurpose catheter, coronary guidewire, and monorail angioplasty balloon, the sheath tip was successfully wired through its inner lumen, trapped from the inside with the balloon, and removed from the body via a large femoral vein sheath, without complications. The approach detailed in this case may guide future cases and circumvent urgent surgical intervention. PMID:25913843

  15. 30 CFR 77.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding metallic sheaths, armors, and conduits enclosing power conductors. 77.700 Section 77.700 Mineral Resources MINE SAFETY AND HEALTH... AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding § 77.700 Grounding metallic sheaths,...

  16. 30 CFR 77.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Grounding metallic sheaths, armors, and conduits enclosing power conductors. 77.700 Section 77.700 Mineral Resources MINE SAFETY AND HEALTH... AND SURFACE WORK AREAS OF UNDERGROUND COAL MINES Grounding § 77.700 Grounding metallic sheaths,...

  17. 30 CFR 75.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Grounding metallic sheaths, armors, and conduits enclosing power conductors. 75.700 Section 75.700 Mineral Resources MINE SAFETY AND HEALTH... Grounding § 75.700 Grounding metallic sheaths, armors, and conduits enclosing power conductors. All...

  18. 30 CFR 75.700 - Grounding metallic sheaths, armors, and conduits enclosing power conductors.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 30 Mineral Resources 1 2011-07-01 2011-07-01 false Grounding metallic sheaths, armors, and conduits enclosing power conductors. 75.700 Section 75.700 Mineral Resources MINE SAFETY AND HEALTH... Grounding § 75.700 Grounding metallic sheaths, armors, and conduits enclosing power conductors. All...

  19. PGPR: A novel strategy for the control of rice sheath blight disease

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Sheath blight caused by Rhizoctonia solani is the most important rice disease in Texas, Arkansas, Mississippi and other southern states. Due to the lack of sheath blight resistance in most commonly planted cultivars, southern rice famers apply more than 1 million pounds of fungicides annually to co...

  20. RAPID COMMUNICATION: On the applicability of Sato's equation to capacitative radio frequency sheaths

    NASA Astrophysics Data System (ADS)

    Balakrishnan, J.; Nagabhushana, G. R.

    2000-12-01

    We show that the time-dependent version of Sato's equation, when applied to capacitative radio frequency sheaths, is no longer independent of the electric field of the space charge, and we discuss the use of the equation for a specific sheath model.

  1. Ultrastructure and chemical composition of the sheath of Leptothrix discophora SP-6.

    PubMed Central

    Emerson, D; Ghiorse, W C

    1993-01-01

    Light microscopy and transmission electron microscopy of thin sections and metal-shadowed specimens showed that the sheath of Leptothrix discophora SP-6 (ATCC 51168) is a tube-like extracellular polymeric structure consisting of a condensed fabric of 6.5-nm-diameter fibrils underlying a more diffuse outer capsular layer. In thin sections, outer membrane bridges seen to contact the inner sheath layer suggested that the sheath fabric was attached to the outer layer of the gram-negative cell wall. The capsular polymers showed an affinity for cationic colloidal iron and polycationic ferritin, indicating that they carry a negative charge. Cell-free sheaths were isolated by treatment with a mixture of lysozyme, EDTA, and N-lauroylsarcosine (Sarkosyl) or sodium dodecyl sulfate (SDS). Both Sarkosyl- and SDS-isolated sheaths were indistinguishable in microscopic appearance. However, the Mn-oxidizing activity of Sarkosyl-isolated sheaths was more stable than that of SDS-isolated sheaths. The Sarkosyl-isolated sheaths also contained more 2-keto-3-deoxyoctanoic acid and more outer membrane protein than SDS-isolated sheaths. The oven-dried mass of detergent-isolated sheaths represented approximately 9% of the total oven-dried biomass of SP-6 cultures; the oven-dried sheaths contained 38% C, 6.9% N, 6% H, and 2.1% S and approximately 34 to 35% carbohydrate (polysaccharide), 23 to 25% protein, 8% lipid, and 4% inorganic ash. Gas-liquid chromatography showed that the polysaccharide was an approximately 1:1 mixture of uronic acids (glucuronic, galacturonic, and mannuronic acids and at least one other unidentified uronic acid) and an amino sugar (galactosamine). Neutral sugars were not detected. Amino acid analysis showed that sheath proteins were enriched in cysteine (6 mol%). The cysteine residues in the sheath proteins probably provide sulfhydryls for disulfide bonds that play an important role in maintaining the structural integrity of the sheath (D. Emerson and W.C. Ghiorse, J

  2. Ultrastructure and chemical composition of the sheath of Leptothrix discophora SP-6.

    PubMed

    Emerson, D; Ghiorse, W C

    1993-12-01

    Light microscopy and transmission electron microscopy of thin sections and metal-shadowed specimens showed that the sheath of Leptothrix discophora SP-6 (ATCC 51168) is a tube-like extracellular polymeric structure consisting of a condensed fabric of 6.5-nm-diameter fibrils underlying a more diffuse outer capsular layer. In thin sections, outer membrane bridges seen to contact the inner sheath layer suggested that the sheath fabric was attached to the outer layer of the gram-negative cell wall. The capsular polymers showed an affinity for cationic colloidal iron and polycationic ferritin, indicating that they carry a negative charge. Cell-free sheaths were isolated by treatment with a mixture of lysozyme, EDTA, and N-lauroylsarcosine (Sarkosyl) or sodium dodecyl sulfate (SDS). Both Sarkosyl- and SDS-isolated sheaths were indistinguishable in microscopic appearance. However, the Mn-oxidizing activity of Sarkosyl-isolated sheaths was more stable than that of SDS-isolated sheaths. The Sarkosyl-isolated sheaths also contained more 2-keto-3-deoxyoctanoic acid and more outer membrane protein than SDS-isolated sheaths. The oven-dried mass of detergent-isolated sheaths represented approximately 9% of the total oven-dried biomass of SP-6 cultures; the oven-dried sheaths contained 38% C, 6.9% N, 6% H, and 2.1% S and approximately 34 to 35% carbohydrate (polysaccharide), 23 to 25% protein, 8% lipid, and 4% inorganic ash. Gas-liquid chromatography showed that the polysaccharide was an approximately 1:1 mixture of uronic acids (glucuronic, galacturonic, and mannuronic acids and at least one other unidentified uronic acid) and an amino sugar (galactosamine). Neutral sugars were not detected. Amino acid analysis showed that sheath proteins were enriched in cysteine (6 mol%). The cysteine residues in the sheath proteins probably provide sulfhydryls for disulfide bonds that play an important role in maintaining the structural integrity of the sheath (D. Emerson and W.C. Ghiorse, J

  3. Immunohistochemical study of cytoskeletal and extracellular matrix components in the notochord and notochordal sheath of amphioxus

    PubMed Central

    Bočina, Ivana; Saraga-Babić, Mirna

    2006-01-01

    A major cytoskeletal and extracellular matrix proteins of the amphioxus notochordal cells and sheath were detected by immunohistochemical techniques. The three-layered amphioxus notochordal sheath strongly expressed fish collagen type I in its outer and middle layers, while in the innermost layer expression did not occur. The amphioxus notochordal sheath was reactive to applied anti-human antibodies for intermediate filament proteins such as cytokeratins, desmin and vimentin, as well as to microtubule components (ß-tubulin), particularly in the area close to the epipharyngeal groove. Alpha-smooth muscle actin was expressed in some notochordal cells and in the area of the notochordal attachment to the sheath. Thus muscular nature of notochordal cells was shown by immunohistochemistry in tissue section. Our results confirm that genes encoding intermediate filament proteins, microtubules and microfilaments are highly conserved during evolution. Collagen type I was proven to be the key extracellular matrix protein that forms the amphioxus notochordal sheath. PMID:16733537

  4. The tail sheath structure of bacteriophage T4: a molecular machine for infecting bacteria

    SciTech Connect

    Aksyuk, Anastasia A.; Leiman, Petr G.; Kurochkina, Lidia P.; Shneider, Mikhail M.; Kostyuchenko, Victor A.; Mesyanzhinov, Vadim V.; Rossmann, Michael G.

    2009-07-22

    The contractile tail of bacteriophage T4 is a molecular machine that facilitates very high viral infection efficiency. Its major component is a tail sheath, which contracts during infection to less than half of its initial length. The sheath consists of 138 copies of the tail sheath protein, gene product (gp) 18, which surrounds the central non-contractile tail tube. The contraction of the sheath drives the tail tube through the outer membrane, creating a channel for the viral genome delivery. A crystal structure of about three quarters of gp18 has been determined and was fitted into cryo-electron microscopy reconstructions of the tail sheath before and after contraction. It was shown that during contraction, gp18 subunits slide over each other with no apparent change in their structure.

  5. Computational study on reliability of sheath width measurement by the cutoff probe in low pressure plasmas

    NASA Astrophysics Data System (ADS)

    Kim, D.-W.; You, S.-J.; Kim, J.-H.; Seong, D.-J.; Chang, H.-Y.; Oh, W.-Y.

    2015-11-01

    Recently, the technique for measurement of the sheath width by using the cutoff probe and its equivalent circuit model was proposed and conducted experimentally. In this study, we investigate the reliability of this technique based on the computational simulation. The simulation of three-dimensional Finite-Difference Time-Domain reproduces the transmission spectrum of the cutoff probe with an input parameter of sheath width. We measure the sheath width by using the circuit model and calculate the discrepancy between them under various input plasma densities and sheath widths. The results show the acceptable discrepancy under all of the conditions we studied (the largest discrepancy is about 45%). This indicates that the technique for measurement of sheath width around the floating tip of cutoff probe is robust and reliable. A shorter version of this contribution is due to be published in PoS at: 1st EPS conference on Plasma Diagnostics

  6. An investigation of friction-based tendon sheath model appropriate for control purposes

    NASA Astrophysics Data System (ADS)

    Do, T. N.; Tjahjowidodo, T.; Lau, M. W. S.; Phee, S. J.

    2014-01-01

    The tendon sheath mechanism plays an important role in many robotic systems from surgical devices to robot hands. However, many unexpected properties such as nonlinear hysteresis and backlash, which appear in the tendon sheath system, cause major losses in force transmission. This report deals with the characterization of hysteresis phenomenon, which is attributed to the presence of frictional effects on its elements, in a tendon-sheath driven surgical robot. Unlike various approaches presented in the literature that utilized multiple lumped mass elements, this proposed approach models the tendon sheath as one element. A new dynamic friction model that allows accurate description of friction lag and hysteresis behavior in two regimes, i.e. presliding and sliding regimes, for a sheath in arbitrary configuration such as helical and spatial shape has been developed.

  7. A Sheath Model for Negative Ion Sources Including the Formation of a Virtual Cathode

    SciTech Connect

    McAdams, R.; King, D. B.; Surrey, E.

    2011-09-26

    A one dimensional model of the sheath between the plasma and the wall in a negative ion source has been developed. The plasma consists of positive ions, electrons and negative ions. The model takes into account the emission of negative ions from the wall into the sheath and thus represents the conditions in a caesiated ion source with surface production of negative ions. At high current densities of the emitted negative ions, the sheath is unable to support the transport of all the negative ions to the plasma and a virtual cathode is formed. This model takes this into account and allows the calculation of the transported negative ions across the sheath with the virtual cathode. The model has been extended to allow the linkage between plasma conditions at the sheath edge and the plasma to be made. Comparisons are made between the results of the model and experimental measurements.

  8. Composite pheochromocytoma with a malignant peripheral nerve sheath tumor: Case report and review of the literature.

    PubMed

    Namekawa, Takeshi; Utsumi, Takanobu; Imamoto, Takashi; Kawamura, Koji; Oide, Takashi; Tanaka, Tomoaki; Nihei, Naoki; Suzuki, Hiroyoshi; Nakatani, Yukio; Ichikawa, Tomohiko

    2016-07-01

    Adrenal tumors with more than one cellular component are uncommon. Furthermore, an adrenal tumor composed of a pheochromocytoma and a malignant peripheral nerve sheath tumor is extremely rare. A composite pheochromocytoma with malignant peripheral nerve sheath tumor in a 42-year-old man is reported here. After adequate preoperative control, left adrenalectomy was performed simultaneously with resection of the ipsilateral kidney for spontaneous rupture of the left adrenal tumor. Pathological findings demonstrated pheochromocytoma and malignant peripheral nerve sheath tumor in a ruptured adrenal tumor. To date, there have been only four reported cases of composite pheochromocytoma with malignant peripheral nerve sheath tumor, so the present case is only the fifth case in the world. Despite the very poor prognosis of patients with pheochromocytoma and malignant peripheral nerve sheath tumors reported in the literature, the patient remains well without evidence of recurrence or new metastatic lesions at 36 months postoperatively. PMID:27338175

  9. Hertwig's epithelial root sheath cell behavior during initial acellular cementogenesis in rat molars.

    PubMed

    Yamamoto, Tsuneyuki; Yamamoto, Tomomaya; Yamada, Tamaki; Hasegawa, Tomoka; Hongo, Hiromi; Oda, Kimimitsu; Amizuka, Norio

    2014-11-01

    This study was designed to examine developing acellular cementum in rat molars by immunohistochemistry, to elucidate (1) how Hertwig's epithelial root sheath disintegrates and (2) whether epithelial sheath cells transform into cementoblasts through epithelial-mesenchymal transition (EMT). Initial acellular cementogenesis was divided into three developmental stages, which can be seen in three different portions of the root: portion 1, where the epithelial sheath is intact; portion 2, where the epithelial sheath becomes fragmented; and portion 3, where acellular cementogenesis begins. Antibodies against three kinds of matrix proteinases, which degrade epithelial sheath-maintaining factors, including basement membrane and desmosomes, were used to investigate proteolytic activity of the epithelial sheath. Tissue non-specific alkaline phosphatase (TNALP) and keratin were used to investigate EMT. Epithelial sheath cells showed immunoreactivity for all three enzymes at fragmentation, which suggests that epithelial sheath disintegration is enzymatically mediated. Dental follicle cells and cementoblasts showed intense immunoreactivity for TNALP, and from portion 1 through to 3, the reaction extended from the alveolar bone-related zone to the root-related zone. Cells possessing keratin/TNALP double immunoreactivity were virtually absent. Keratin-positive epithelial sheath cells showed negligible immunoreactivity for TNALP, and epithelial cells did not appear to migrate to the dental follicle. Together, these findings suggest that a transition phenotype between epithelial cells and cementoblasts does not exist in the developing dental follicle and hence that epithelial sheath cells do not undergo EMT during initial acellular cementogenesis. In brief, this study supports the notion that cementoblasts derive from the dental follicle. PMID:24859538

  10. Particle trap to sheath contact for a gas-insulated transmission line having a corrugated outer conductor

    DOEpatents

    Fischer, William H.; Cookson, Alan H.; Yoon, Kue H.

    1984-04-10

    A particle trap to outer elongated conductor or sheath contact for gas-insulated transmission lines. The particle trap to outer sheath contact of the invention is applicable to gas-insulated transmission lines having either corrugated or non-corrugated outer sheaths. The contact of the invention includes an electrical contact disposed on a lever arm which in turn is rotatably disposed on the particle trap and biased in a direction to maintain contact between the electrical contact and the outer sheath.