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Sample records for axis radiographic hydrodynamic

  1. Status of the Dual-Axis Radiographic Hydrodynamics Test Facility

    SciTech Connect

    Burns, M.J.; Allison, P.W.; Carlson, R.L.; Downing, J.N.; Moir, D.C.; Shurter, R.P.

    1996-09-01

    The Dual-Axis Radiographic Hydrodynamics Test (DARHT) Facility will employ two electron linear induction accelerators to produce intense, bremsstrahlung x-ray pulses for flash radiography with sub-millimeter spatial resolution of very dense (attentuations>10{sup 5}), dynamic objects. We will produce an intense x-ray pulse using a 19.75-MeV, 3.5-4 kA, 60-ns flattop electron beam focused on a tungsten target. A 3.75-MeV injector with either a cold velvet cathode or a laser-driven photocathode will produce a beam to be accelerated through a series of 64 ferrite-loaded induction cells with solenoid focusing. Accelerator technology demonstrations have been underway for several years at the DARHT Integrated Test Stand and results including beam energy, emittance, and beam breakup measurements are discussed.

  2. Dual Axis Radiographic Hydrodynamic Test Facility mitigation action plan. Annual report for 1998

    SciTech Connect

    Haagenstad, T.

    1999-01-15

    This Mitigation Action Plan Annual Report (MAPAR) has been prepared as part of implementing the Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) Mitigation Action Plan (MAP) to protect workers, soils, water, and biotic and cultural resources in and around the facility.

  3. The dual axis radiographic hydrodynamic test (DARHT) facility personnel safety system (PSS) control system

    SciTech Connect

    Jacquez, Edward B

    2008-01-01

    The mission of the Dual Axis Radiograph Hydrodynamic Test (DARHT) Facility is to conduct experiments on dynamic events of extremely dense materials. The PSS control system is designed specifically to prevent personnel from becoming exposed to radiation and explosive hazards during machine operations and/or the firing site operation. This paper will outline the Radiation Safety System (RSS) and the High Explosive Safety System (HESS) which are computer-controlled sets of positive interlocks, warning devices, and other exclusion mechanisms that together form the PSS.

  4. Dual axis radiographic hydrodynamic test facility. Final environmental impact statement, Volume 2: Public comments and responses

    SciTech Connect

    1995-08-01

    On May 12, 1995, the U.S. Department of Energy (DOE) issued the draft Dual Axis Radiographic Hydrodynamic Test Facility Environmental Impact Statement (DARHT EIS) for review by the State of New Mexico, Indian Tribes, local governments, other Federal agencies, and the general public. DOE invited comments on the accuracy and adequacy of the draft EIS and any other matters pertaining to their environmental reviews. The formal comment period ran for 45 days, to June 26, 1995, although DOE indicated that late comments would be considered to the extent possible. As part of the public comment process, DOE held two public hearings in Los Alamos and Santa Fe, New Mexico, on May 31 and June 1, 1995. In addition, DOE made the draft classified supplement to the DARHT EIS available for review by appropriately cleared individuals with a need to know the classified information. Reviewers of the classified material included the State of New Mexico, the U.S. Environmental Protection Agency, the Department of Defense, and certain Indian Tribes. Volume 2 of the final DARHT EIS contains three chapters. Chapter 1 includes a collective summary of the comments received and DOE`s response. Chapter 2 contains the full text of the public comments on the draft DARHT EIS received by DOE. Chapter 3 contains DOE`s responses to the public comments and an indication as to how the comments were considered in the final EIS.

  5. Dual Axis Radiographic Hydrodynamic Test Facility mitigation action plan. Annual report for 1997

    SciTech Connect

    Haagenstad, H.T.

    1998-01-15

    This Mitigation Action Plan Annual Report (MAPAR) has been prepared by the US Department of Energy (DOE) as part of implementing the Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) Mitigation Action Plan (MAP). This MAPAR provides a status on specific DARHT facility design- and construction-related mitigation actions that have been initiated in order to fulfill DOE`s commitments under the DARHT MAP. The functions of the DARHT MAP are to (1) document potentially adverse environmental impacts of the Phased Containment Option delineated in the Final EIS, (2) identify commitments made in the Final EIS and ROD to mitigate those potential impacts, and (3) establish Action Plans to carry out each commitment (DOE 1996). The DARHT MAP is divided into eight sections. Sections 1--5 provide background information regarding the NEPA review of the DARHT project and an introduction to the associated MAP. Section 6 references the Mitigation Action Summary Table which summaries the potential impacts and mitigation measures; indicates whether the mitigation is design-, construction-, or operational-related; the organization responsible for the mitigation measure; and the projected or actual completion data for each mitigation measure. Sections 7 and 8 discuss the Mitigation Action Plan Annual Report and Tracking System commitment and the Potential Impacts, Commitments, and Action Plans respectively. Under Section 8, potential impacts are categorized into five areas of concern: General Environment, including impacts to air and water; Soils, especially impacts affecting soil loss and contamination; Biotic Resources, especially impacts affecting threatened and endangered species; Cultural/Paleontological Resources, especially impacts affecting the archeological site known as Nake`muu; and Human Health and Safety, especially impacts pertaining to noise and radiation. Each potential impact includes a brief statement of the nature of the impact and its cause(s). The commitment

  6. Radionuclides in Small Mammals Collected at the Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility during 2001-- 2003

    SciTech Connect

    P.R. Fresquez

    2005-01-20

    Rodents are effective indicators of environmental contamination and the Dual-Axis Radiographic Hydrodynamic Test (DARHT) Facility Mitigation Action Plan specifies the (radionuclide) comparison of small mammals to baseline levels to determine if there are any impacts as a result of operations. Consequently, samples of (whole body) field mice (Peromyscus spp.) were collected from within the grounds of the DARHT facility at Los Alamos National Laboratory, Technical Area 15, from 2001 through 2003. Samples were analyzed for {sup 3}H, {sup 137}Cs, {sup 90}Sr, {sup 241}Am, {sup 238}Pu, {sup 239,240}Pu, {sup 234}U, {sup 235}U, and {sup 238}U. Results, which represent three years since the start of operations in 2000, were compared with baseline statistical reference level (BSRL) data established over a four-year-long preoperational period. Most radionuclides in mice were either at nondetectable levels or within BSRLs. The few radionuclides that were above BSRLs included U isotopes; and the ratios of some samples indicated depleted U sources. Although the amounts of U in some samples were just above BSRLs, and since depleted U is less soluble and less toxic (chemical and radioactive) than naturally occurring U, the very small levels in the mice collected around the DARHT facility grounds are unlikely to pose a threat to predators that feed upon them.

  7. Concentrations of Radionuclides and Trace Elements in Environmantal Media arond te Dual-Axis Radiographic Hydrodynamic Test Facilit at Los Alamos National Laboratory during 2005

    SciTech Connect

    G.J.Gonzales; P.R. Fresquez; C.D.Hathcock; D.C. Keller

    2006-05-15

    The Mitigation Action Plan (MAP) for the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory requires that samples of biotic and abiotic media be collected after operations began to determine if there are any human health or environmental impacts. The DARHT facility is the Laboratory's principal explosive test facility. To this end, samples of soil and sediment, vegetation, bees, and birds were collected around the facility in 2005 and analyzed for concentrations of {sup 3}H, {sup 137}Cs, {sup 90}Sr, {sup 238}Pu, {sup 239,240}Pu, {sup 241}Am, {sup 234}U, {sup 235}U, {sup 238}U, Ag, As, Ba, Be, Cd, Cr, Cu, Hg, Ni, Pb, Sb, Se, and Tl. Bird populations have also been monitored. Contaminant results, which represent up to six sample years since the start of operations, were compared with (1) baseline statistical reference levels (BSRLs) established over a four-year preoperational period before DARHT facility operations, (2) screening levels (SLs), and (3) regulatory standards. Most radionuclides and trace elements were below BSRLs and those few samples that contained radionuclides and trace elements above BSRLs were below SLs. Concentrations of radionuclides and nonradionuclides in biotic and abiotic media around the DARHT facility do not pose a significant human health hazard. The total number of birds captured and number of species represented were similar in 2003 and 2004, but both of these parameters increased substantially in 2005. Periodic interruption of the scope and schedule identified in the MAP generally should have no impact on meeting the intent of the MAP. The risk of not sampling one of the five media in any given year is that if a significant impact to contaminant levels were to occur there would exist a less complete understanding of the extent of the change to the baseline for these media and to the ecosystem as a whole. Since the MAP is a requirement that was established under the regulatory framework of the

  8. Radiographic results from the NTLX series of hydrodynamic experiments

    SciTech Connect

    Olson, R. T.; Oro, D. M.; Anderson, B. G.; Studebaker, J. K.; Alvey, K.; Peterson, K.; Froggett, B. C.

    2001-01-01

    The NTLX series of experiments are focused on measuring the shock induced hydrodynamic flow of a Sn-PMMA target. For these experiments multi-frame flash X-ray radiography is used to measure the position of the Sn-PMMA target interface and the location of shock in the PMMA as a function of time. Four radiographs are acquired at 700 ns intervals having a line-of-sight following the target's axis of symmetry. Because the Xray spectrum from the sources has an end-point energy of {approx}300 keV with a strong component of {approx}60 keV tungsten K-line radiation, the Sn portion of the target is radiographically opaque. However, X-rays are transmitted through the PMMA portion of the target thereby allowing motion of the Sn-PMMA interface to be imaged. Also, the shock location is tracked as a function of time due to the density increase in the shocked PMMA. The resulting radiographs are analyzed to provide the trajectory and shape of both the shock and Sn-PMMA interface. In addition, the shock velocity in the Sn is determined for asymmetric target geometries.

  9. RADIOGRAPHIC RESULTS FROM THE NTLX SERIES OF HYDRODYNAMIC EXPERIMENTS

    SciTech Connect

    R.T. OLSON; D.M. ORO; ET AL

    2001-06-01

    The NTLX series of experiments are focused on measuring the shock induced hydrodynamic flow of a Sn-PMMA target. For these experiments multi-frame flash X-ray radiography is used to measure the position of the Sn-PMMA target interface and the location of shock in the PMMA as a function of time. Four radiographs are acquired at 700 ns intervals having a line-of-sight following the target's axis of symmetry. Because the X-ray spectrum from the sources has an end-point energy of {approx}300 keV with a strong component of {approx}60 keV tungsten K-line radiation, the Sn portion of the target is radiographically opaque. However, X-rays are transmitted through the PMMA portion of the target thereby allowing motion of the Sn-PMMA interface to be imaged. Also, the shock location is tracked as a function of time due to the density increase in the shocked PMMA. The resulting radiographs are analyzed to provide the trajectory and shape of both the shock and Sn-PMMA interface. In addition, the shock velocity in the Sn is determined for asymmetric target geometries.

  10. The hinge axis concept: a radiographic study of its relevance.

    PubMed

    Hellsing, G; Hellsing, E; Eliasson, S

    1995-01-01

    The "hinge axis concept" maintains that the mandible moves around a transverse horizontal axis through both condyles. Since it was introduced in the 1920s it has had a profound impact on clinical dental practices all over the world. By use of the radiographic subtraction technique, we demonstrated that an increase in the occlusal vertical dimension of 4 to 7 mm in the retruded position resulted in a small positional change (range 0.31 to 1.84 mm) in an unpredictable direction. Pure rotation did not occur; however, the condylar displacement is probably of minor clinical importance in prosthodontic restoration.

  11. The Mechanical Axis of the First Ray: A Radiographic Assessment in Hallux Abducto Valgus Evaluation.

    PubMed

    LaPorta, Guido A; Nasser, Ellianne M; Mulhern, Jennifer L; Malay, D Scot

    2016-01-01

    The present report describes a new method of hallux abducto valgus deformity correction planning using the mechanical axis of the medial column (mechanical axis planning). This method of radiographic evaluation identifies an ideal position for the first metatarsal after correction and is useful regardless of the surgical procedure chosen. We retrospectively reviewed 200 radiographs to identify a "normal" value for the mechanical axis angle. We reviewed 100 radiographs of patients with hallux abducto valgus deformity (deformity group) and 100 radiographs of patients without hallux abducto valgus deformity (control group). The deformity group revealed an M1-M2 anatomic axis angle of 13.5° ± 2.83° and an M1-M2 mechanical axis angle of 11.58° ± 1°. The control group revealed an M1-M2 anatomic axis angle of 7.5° ± 1.76° and an M1-M2 mechanical axis angle of 11.19° ± 0.9°. The differences in the M1-M2 anatomic axis angle and M1-M2 mechanical axis angle were statistically significant between the control and deformity groups. We sought to provide a reliable method for planning hallux abducto valgus deformity correction by aligning the mechanical axis of the medial column and the mechanical axis of the first ray to the "normal" value of 11° to reduce the deformity.

  12. Inductive voltage adder advanced hydrodynamic radiographic technology demonstration

    SciTech Connect

    Mazarakis, M.G.; Poukey, J.W.; Maenchen; Rovang, D.C.

    1997-04-01

    This paper presents the design, results, and analysis of a high-brightness electron beam technology demonstration experiment completed at Sandia National Laboratories, performed in collaboration with Los Alamos National Laboratory. The anticipated electron beam parameters were: 12 MeV, 35-40 kA, 0.5-mm rms radius, and 40-ns full width half maximum (FWHM) pulse duration. This beam, on an optimum thickness tantalum converter, should produce a very intense x-ray source of {approximately} 1.5-mm spot size and 1 kR dose @ 1 m. The accelerator utilized was SABRE, a pulsed inductive voltage adder, and the electron source was a magnetically immersed foilless electron diode. For these experiments, SABRE was modified to high-impedance negative-polarity operation. A new 100-ohm magnetically insulated transmission line cathode electrode was designed and constructed; the cavities were rotated 180{degrees} poloidally to invert the central electrode polarity to negative; and only one of the two pulse forming lines per cavity was energized. A twenty- to thirty-Tesla solenoidal magnet insulated the diode and contained the beam at its extremely small size. These experiments were designed to demonstrate high electron currents in submillimeter radius beams resulting in a high-brightness high-intensity flash x-ray source for high-resolution thick-object hydrodynamic radiography. The SABRE facility high-impedance performance was less than what was hoped. The modifications resulted in a lower amplitude (9 MV), narrower-than-anticipated triangular voltage pulse, which limited the dose to {approximately} 20% of the expected value. In addition, halo and ion-hose instabilities increased the electron beam spot size to > 1.5 mm. Subsequent, more detailed calculations explain these reduced output parameters. An accelerator designed (versus retrofit) for this purpose would provide the desired voltage and pulse shape.

  13. Use of the fulcrum axis improves the accuracy of true anteroposterior radiographs of the shoulder.

    PubMed

    Braunstein, V; Kirchhoff, C; Ockert, B; Sprecher, C M; Korner, M; Mutschler, W; Wiedemann, E; Biberthaler, P

    2009-08-01

    In 100 patients the fulcrum axis which is the line connecting the anterior tip of the coracoid and the posterolateral angle of the acromion, was used to position true anteroposterior radiographs of the shoulder. This method was then compared with the conventional radiological technique in a further 100 patients. Three orthopaedic surgeons counted the number of images without overlap between the humeral head and glenoid and calculated the amount of the glenoid surface visible in each radiograph. The analysis was repeated for intraobserver reliability. The learning curves of both techniques were studied. The amount of free visible glenoid space was significantly higher using the fulcrum-axis method (64 vs 31) and the comparable glenoid size increased significantly (8.56 vs 6.47). Thus the accuracy of the anteroposterior radiographs of the shoulder is impaired by using this technique. The intra and interobserver reliability showed a high consistency. No learning curve was observed for either technique.

  14. High-speed x-ray radiographic measurement of laser-driven hydrodynamic instability

    NASA Astrophysics Data System (ADS)

    Shiraga, Hiroyuki; Azechi, Hiroshi; Nakai, Mitsuo; Shigemori, Keisuke; Nishikino, Masaharu; Sakaiya, Tatsuhiro; Fujioka, Shinsuke; Tamari, Yohei; Yamanaka, Tatsuhiko

    2003-07-01

    Hydrodynamic instability in laser-irradiated targets have been investigated in detail by using ultra high-speed x-ray radiographic technique. Recently developed high-resolution x-ray imaging for laser-driven Rayleigh-Taylor (RT) instability experiments as well as data including RT growth rate, ablation density and plasma density profile are desribed. Results are of great importance for comprehensive understanding of the dispersion relation of the laser-driven RT instability. Especially, direct observation of the ablation density was first achieved with temporal and spatial resolutions of 100 ps and 3 μm, respectively. Imaging techniques includes x-ray Moire imaging, x-ray penumbral imaging and Fresnel phase zone plate imaging coupled with x-ray streak cameras or x-ray CCD cameras. Experiments were performed by using Gekko-XII/HIPER laser system at the Institute of Laser Engineering, Osaka University.

  15. AXIS: An instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF

    SciTech Connect

    Hall, G. N. Izumi, N.; Tommasini, R.; Carpenter, A. C.; Palmer, N. E.; Zacharias, R.; Felker, B.; Holder, J. P.; Allen, F. V.; Bell, P. M.; Bradley, D.; Montesanti, R.; Landen, O. L.

    2014-11-15

    Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV–200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

  16. AXIS: an instrument for imaging Compton radiographs using the Advanced Radiography Capability on the NIF.

    PubMed

    Hall, G N; Izumi, N; Tommasini, R; Carpenter, A C; Palmer, N E; Zacharias, R; Felker, B; Holder, J P; Allen, F V; Bell, P M; Bradley, D; Montesanti, R; Landen, O L

    2014-11-01

    Compton radiography is an important diagnostic for Inertial Confinement Fusion (ICF), as it provides a means to measure the density and asymmetries of the DT fuel in an ICF capsule near the time of peak compression. The AXIS instrument (ARC (Advanced Radiography Capability) X-ray Imaging System) is a gated detector in development for the National Ignition Facility (NIF), and will initially be capable of recording two Compton radiographs during a single NIF shot. The principal reason for the development of AXIS is the requirement for significantly improved detection quantum efficiency (DQE) at high x-ray energies. AXIS will be the detector for Compton radiography driven by the ARC laser, which will be used to produce Bremsstrahlung X-ray backlighter sources over the range of 50 keV-200 keV for this purpose. It is expected that AXIS will be capable of recording these high-energy x-rays with a DQE several times greater than other X-ray cameras at NIF, as well as providing a much larger field of view of the imploded capsule. AXIS will therefore provide an image with larger signal-to-noise that will allow the density and distribution of the compressed DT fuel to be measured with significantly greater accuracy as ICF experiments are tuned for ignition.

  17. Radiographer.

    ERIC Educational Resources Information Center

    Ohio State Univ., Columbus. Center on Education and Training for Employment.

    This document, which is designed for use in developing a tech prep competency profile for the occupation of radiographer, lists technical competencies and competency builders for 18 units pertinent to the health technologies cluster in general as well as those specific to the occupation of radiographer. The following skill areas are covered in the…

  18. Induction cell breakdown experiments for the Dual-Axis Radiographic Hydrotest (DARHT) Facility

    SciTech Connect

    Earley, L.M.; Barnes, G.A.; Eversole, S.A.; Kauppila, T.J.; Keel, G.; Liska, D.J.; Moir, D.C.; Parsons, W.M.; Rader, D.C.

    1991-01-01

    Linear induction cells for the Dual-Axis Radiographic Hydrotest (DARHT) Facility have been tested to determine their high-voltage breakdown characteristics. A variety of full scale insulators were tested both in actual cells and in fixtures simulating induction cells. All insulators were constructed using cross-linked polystyrene (Rexolite). High-voltage pulses up to 550 kV were applied to the insulators using both a 60-ns pulse Blumlein and a 200-ns pulse cable Marx. Two different vacuum gaps were used in these tests, 1.46 and 1.91 cm. The tests were performed at various vacuum levels ranging from 1 {times} 10{sup {minus}6} to 5 {times} 10{sup {minus}8} torr. Breakdown tests of the insulators were also performed with an electron beam generated in the vacuum gap through the use of a velvet emitter. The gap voltage and current were measured using calibrated E-dot and B-dot probes. 15 refs., 7 figs.

  19. On the use of knee functional calibration to determine the medio-lateral axis of the femur in gait analysis: Comparison with EOS biplanar radiographs as reference.

    PubMed

    Sauret, Christophe; Pillet, Hélène; Skalli, Wafa; Sangeux, Morgan

    2016-10-01

    Accurate calibration of the medio-lateral axis of the femur is crucial for clinical decision making based on gait analysis. This study proposes a protocol utilizing biplanar radiographs to provide a reference medio-lateral axis based on the anatomy of the femur. The biplanar radiographs allowed 3D modelling of the bones of the lower limbs and the markers used for motion capture, in the standing posture. A comprehensive analysis was performed and results from biplanar radiographs were reliable for 3D marker localization (±0.35mm) and for 3D localization of the anatomical landmarks (±1mm), leading to a precision of 1° for the orientation of the condylar axis of the femur and a 95% confidence interval of ±3° after registration with motion capture data. The anatomical condylar axis was compared to a conventional, marker-based, axis and three functional calibration techniques (axis transformation, geometric axis fit and DynaKAD). Results for the conventional method show an average difference with the condylar axis of 15° (SD: 6°). Results indicate DynaKAD functional axis was the closest to the anatomical condylar axis, mean: 1° (SD: 5°) when applied to passive knee flexion movement. However, the range of the results exceeded 15° for all methods. Hence, the use of biplanar radiographs, or an alternative imaging technique, may be required to locate the medio-lateral axis of the femur reliably prior to clinical decision making for femur derotational osteotomies.

  20. Measuring x-ray spectra of flash radiographic sources [PowerPoint

    SciTech Connect

    Gehring, Amanda Elizabeth; Espy, Michelle A.; Haines, Todd Joseph; Mendez, Jacob; Moir, David C.; Sedillo, Robert; Shurter, Roger P.; Volegov, Petr Lvovich; Webb, Timothy J

    2015-11-02

    The x-ray spectra of flash radiographic sources are difficult to measure. The sources measured were Radiographic Integrated Test Stand-6 (370 rad at 1 m; 50 ns pulse) and Dual Axis Radiographic Hydrodynamic Test Facility (DARHT) (550 rad at 1 m; 50 ns pulse). Features of the Compton spectrometer are described, and spectra are shown. Additional slides present data on instrumental calibration.

  1. The interleukin-20 receptor axis in early rheumatoid arthritis: novel links between disease-associated autoantibodies and radiographic progression.

    PubMed

    Kragstrup, Tue Wenzel; Greisen, Stinne Ravn; Nielsen, Morten Aagaard; Rhodes, Christopher; Stengaard-Pedersen, Kristian; Hetland, Merete Lund; Hørslev-Petersen, Kim; Junker, Peter; Østergaard, Mikkel; Hvid, Malene; Vorup-Jensen, Thomas; Robinson, William H; Sokolove, Jeremy; Deleuran, Bent

    2016-03-11

    months (Spearman's rho = 0.19 and 0.26, both P < 0.05) in the early RA patients. The IL-22R1 was expressed by osteoclast precursors and in multinucleated osteoclasts. IL-20 and IL-24 increased the secretion of monocyte chemoattractant protein 1 by these cells. This study suggests that IL-20 and IL-24 link RA-associated autoantibodies with radiographic progression via the IL-22R1. Modulation of this axis holds promise as feasible anti-erosive treatment modalities in seropositive RA.

  2. Validation of the greater trochanter method with radiographic measurements of frontal plane hip joint centers and knee mechanical axis angles and two other hip joint center methods.

    PubMed

    Bennett, Hunter J; Shen, Guangping; Weinhandl, Joshua T; Zhang, Songning

    2016-09-06

    Several motion capture methods exist for predicting hip joint centers (HJC). These methods include regression models, functional joints, and projections from greater trochanters. While regression and functional methods have been compared to imaging techniques, the TROCH method has not been previously validated. The purpose of this study was to compare frontal-plane HJCs and knee mechanical axis angles estimated using the greater trochanter method with a regression (Bell) and a functional method against those obtained using radiographs. Thirty-five participants underwent a long-standing anteroposterior radiograph, and performed static and functional motion capture trials. The Bell, functional, and trochanter HJCs were constructed to predict mechanical axes and compare HJC locations. One-way repeated measures ANOVAs were used to compare mechanical axes and HJC locations estimated by motion capture methods and measured using radiographs (p<0.05). All methods overestimated mechanical axes compared to radiographs (<2°), but were not different. Mediolateral HJC locations and inter-HJC widths were similar between methods; however, inter-HJC widths were underestimated (average 3.7%) compared to radiographs. The Bell HJC was more superior and anterior to both functional and trochanter methods. The trochanter HJC was more posterior to both methods. The Bell method outperformed the other methods in leg length predictions compared to radiographs. Although differences existed between methods, all frontal-plane HJC location differences were <1.7cm. This study validated the trochanter HJC prediction method mediolaterally and vertically (with small respective correction factors). Therefore, all HJC methods seem to be viable in predicting mechanical axes and frontal-plane HJC locations compared with radiographs.

  3. Hydrodynamic numerical simulation of diffuser for horizontal axis marine current turbine based on CFD

    NASA Astrophysics Data System (ADS)

    Chen, H.; Zhou, D.

    2014-03-01

    In order to comprehensively study the hydrodynamic characteristics of diffuser for marine current turbine with a postpositive bulb, a geometric model of the turbine was established. Three-dimensional CFD simulation of turbulent flow was performed based on the incompressible continuity equation, the Navier-Stokes equations and the Spalart-Allmaras turbulence model. The influence of diffuser was calculated and analyzed by numerical results, which were also compared with model test results. Results showed that the numerical results agree fairly well with model test and the maximum error of impeller efficiency and power is 1.5% and 1.8% in the rated water velocity condition, which are less than 5.8% and 5.5% under other cases respectively. The new type marine current turbine with a bulb for erecting motor which is different from regular, and the diffuser can aggregate water flow, raise inlet water velocity more than 3% and efficiency of impeller effectively increased. After diffuser was added, the power coefficient curve rose over the full range, so the high power area became widely, and then remarkably prolonged power time as well as increased generated energy, it is also significant for efficient utilization of marine current energy and environmental pollution remission.

  4. Experimental study on hydrodynamic characteristics of vertical-axis floating tidal current energy power generation device

    NASA Astrophysics Data System (ADS)

    Ma, Yong; Li, Teng-fei; Zhang, Liang; Sheng, Qi-hu; Zhang, Xue-wei; Jiang, Jin

    2016-10-01

    To study the characteristics of attenuation, hydrostatic towage and wave response of the vertical-axis floating tidal current energy power generation device (VAFTCEPGD), a prototype is designed and experiment is carried out in the towing tank. Free decay is conducted to obtain attenuation characteristics of the VAFTCEPGD, and characteristics of mooring forces and motion response, floating condition, especially the lateral displacement of the VAFTCEPGD are obtained from the towing in still water. Tension response of the #1 mooring line and vibration characteristics of the VAFTCEPGD in regular waves as well as in level 4 irregular wave sea state with the current velocity of 0.6 m/s. The results can be reference for theoretical study and engineering applications related to VAFTCEPGD.

  5. Comparison of Mechanical Axis and Dynamic Range Assessed with Weight Bearing Radiographs and Navigation System in Closed Wedge High Tibial Osteotomy.

    PubMed

    Bae, Dae Kyung; Lee, Jong Whan; Cho, Seong Jin; Song, Sang Jun

    2017-09-01

    To compare navigation and weight bearing radiographic measurements of mechanical axis (MA) before and after closed wedge high tibial osteotomy (HTO) and to evaluate post-osteotomy changes in MA assessed during application of external varus or valgus force. Data from 30 consecutive patients (30 knees) who underwent computer-assisted closed-wedge HTO were prospectively analyzed. Pre- and postoperative weight bearing radiographic evaluation of MA was performed. Under navigation guidance, pre- and post-osteotomy MA values were measured in an unloaded position. Any change in the post-osteotomy MA in response to external varus or valgus force, which was named as dynamic range, was evaluated with the navigation system. The navigation and weight bearing radiographic measurements were compared. Although there was a positive correlation between navigation and radiographic measurements, the reliability of navigation measurements of coronal alignment was reduced after osteotomy and wedge closing. The mean post-osteotomy MA value measured with the navigation was 3.5°±0.8° valgus in an unloaded position. It was 1.3°±0.8° valgus under varus force and 5.8°±1.1° valgus under valgus force. The average dynamic range was >±2°. Potential differences between the postoperative MAs assessed by weight bearing radiographs and the navigation system in unloaded position should be considered during computer-assisted closed wedge HTO. Care should be taken to keep the dynamic range within the permissible range of alignment goal in HTO.

  6. Evaluation of Methods to Increase Beam Pulse Width on the DARHT Axis-II Accelerator

    DTIC Science & Technology

    2013-06-01

    lanl.gov Abstract The second axis (Axis II) of the Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility at Los Alamos National Laboratory ( LANL ...of the cell pulses are of less importance than 665U.S. Government work not protected by U.S. copyright Report Documentation Page Form ApprovedOMB No...19th). Held in San Francisco, CA on 16-21 June 2013., The original document contains color images. 14. ABSTRACT The second axis (Axis II) of the Dual

  7. Annual Report: Hydrodynamics and Radiative Hydrodynamics with Astrophysical Applications

    SciTech Connect

    R. Paul Drake

    2005-12-01

    We report the ongoing work of our group in hydrodynamics and radiative hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining high-quality scaling data using a backlit pinhole and obtaining the first (ever, anywhere) Thomson-scattering data from a radiative shock. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, obtaining the first (ever, anywhere) dual-axis radiographic data using backlit pinholes and ungated detectors. All these experiments have applications to astrophysics, discussed in the corresponding papers either in print or in preparation. We also have obtained preliminary radiographs of experimental targets using our x-ray source. The targets for the experiments have been assembled at Michigan, where we also prepare many of the simple components. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.

  8. X-ray radiographic imaging of hydrodynamic phenomena in radiation driven materials -- shock propagation, material compression and shear flow. Revision 1

    SciTech Connect

    Hammel, B.A.; Kilkenny, J.D.; Munro, D.; Remington, B.A.; Kornblum, H.N.; Perry, T.S.; Phillion, D.W.; Wallace, R.J.

    1994-02-01

    One- and two-dimensional, time resolved x-ray radiographic imaging at high photon energy (5-7 keV) is used to study shock propagation, material motion and compression, and the effects of shear flow in solid density samples which are driven by x-ray ablation with the Nova laser. By backlighting the samples with x-rays and observing the increase in sample areal density due to shock compression, the authors directly measure the trajectory of strong shocks ({approx}40 Mbar) in flight, in solid density plastic samples. Doping a section of the samples with high-Z material (Br) provides radiographic contrast, allowing the measurement of the shock induced particle motion. Instability growth due to shear flow at an interface is investigated by imbedding a metal wire in a cylindrical plastic sample and launching a shock in the axial direction. Time resolved radiographic measurements are made with either a slit-imager coupled to an x-ray streak camera or a pinhole camera coupled to a gated microchannel plate detector, providing {approx} 10-{mu}m spatial and {approx} 100-ps temporal resolution.

  9. DARHT Axis-I Diode Simulations II: Geometrical Scaling

    SciTech Connect

    Ekdahl, Carl A. Jr.

    2012-06-14

    Flash radiography of large hydrodynamic experiments driven by high explosives is a venerable diagnostic technique in use at many laboratories. Many of the largest hydrodynamic experiments study mockups of nuclear weapons, and are often called hydrotests for short. The dual-axis radiography for hydrodynamic testing (DARHT) facility uses two electron linear-induction accelerators (LIA) to produce the radiographic source spots for perpendicular views of a hydrotest. The first of these LIAs produces a single pulse, with a fixed {approx}60-ns pulsewidth. The second axis LIA produces as many as four pulses within 1.6-{micro}s, with variable pulsewidths and separation. There are a wide variety of hydrotest geometries, each with a unique radiographic requirement, so there is a need to adjust the radiographic dose for the best images. This can be accomplished on the second axis by simply adjusting the pulsewidths, but is more problematic on the first axis. Changing the beam energy or introducing radiation attenuation also changes the spectrum, which is undesirable. Moreover, using radiation attenuation introduces significant blur, increasing the effective spot size. The dose can also be adjusted by changing the beam kinetic energy. This is a very sensitive method, because the dose scales as the {approx}2.8 power of the energy, but it would require retuning the accelerator. This leaves manipulating the beam current as the best means for adjusting the dose, and one way to do this is to change the size of the cathode. This method has been proposed, and is being tested. This article describes simulations undertaken to develop scaling laws for use as design tools in changing the Axis-1 beam current by changing the cathode size.

  10. GI Radiographic Tests

    MedlinePlus

    ... Topic / Radiographic Tests in GI Radiographic Tests in GI Basics Commonly Performed Radiographic Tests in Gastroenterology Gastroenterologists ... January 2009. Updated December 2012. Return to Top GI Health Centers Colorectal Cancer Hepatitis C Inflammatory Bowel ...

  11. Interpretation of dental radiographs.

    PubMed

    Woodward, Tony M

    2009-02-01

    Interpretation of dental radiographs is fairly straightforward, with a handful of common patterns making up the majority of pathology. This article covers normal radiographic anatomy, endodontic disease, periodontal disease, neoplastic changes, tooth resorption, caries, and radiographic signs of oral trauma.

  12. Annual Report 2006 for Hydrodynamics and Radiation Hydrodynamics with Astrophysical Applications

    SciTech Connect

    R. Paul Drake

    2007-04-05

    We report the ongoing work of our group in hydrodynamics and radiation hydrodynamics with astrophysical applications. During the period of the existing grant, we have carried out two types of experiments at the Omega laser. One set of experiments has studied radiatively collapsing shocks, obtaining data using a backlit pinhole with a 100 ps backlighter and beginning to develop the ability to look into the shock tube with optical or x-ray diagnostics. Other experiments have studied the deeply nonlinear development of the Rayleigh-Taylor (RT) instability from complex initial conditions, using dual-axis radiographic data with backlit pinholes and ungated detectors to complete the data set for a Ph.D. student. We lead a team that is developing a proposal for experiments at the National Ignition Facility and are involved in experiments at NIKE and LIL. All these experiments have applications to astrophysics, discussed in the corresponding papers. We assemble the targets for the experiments at Michigan, where we also prepare many of the simple components. We also have several projects underway in our laboratory involving our x-ray source. The above activities, in addition to a variety of data analysis and design projects, provide good experience for graduate and undergraduates students. In the process of doing this research we have built a research group that uses such work to train junior scientists.

  13. Tuning the DARHT Axis-II linear induction accelerator focusing

    SciTech Connect

    Ekdahl, Carl A.

    2012-04-24

    Flash radiography of large hydrodynamic experiments driven by high explosives is a well-known diagnostic technique in use at many laboratories, and the Dual-Axis Radiography for Hydrodynamic Testing (DARHT) facility at Los Alamos produces flash radiographs of large hydrodynamic experiments. Two linear induction accelerators (LIAs) make the bremsstrahlung radiographic source spots for orthogonal views of each test. The 2-kA, 20-MeV Axis-I LIA creates a single 60-ns radiography pulse. The 1.7-kA, 16.5-MeV Axis-II LIA creates up to four radiography pulses by kicking them out of a longer pulse that has a 1.6-{mu}s flattop. The Axis-II injector, LIA, kicker, and downstream transport (DST) to the bremsstrahlung converter are described. Adjusting the magnetic focusing and steering elements to optimize the electron-beam transport through an LIA is often called 'tuning.' As in all high-current LIAs, the focusing field is designed to be as close to that of the ideal continuous solenoid as physically possible. In ideal continuous solenoidal transport a smoothly varying beam size can easily be found for which radial forces balance, and the beam is said to be 'matched' to the focusing field. A 'mismatched' beam exhibits unwanted oscillations in size, which are a source of free energy that contributes to emittance growth. This is undesirable, because in the absence of beam-target effects, the radiographic spot size is proportional to the emittance. Tuning the Axis-II LIA is done in two steps. First, the solenoidal focusing elements are set to values designed to provide a matched beam with little or no envelope oscillations, and little or no beam-breakup (BBU) instability growth. Then, steering elements are adjusted to minimize the motion of the centroid of a well-centered beam at the LIA exit. This article only describes the design of the tune for the focusing solenoids. The DARHT Axis-II LIA was required to be re-tuned after installing an accelerator cell to replace a failed

  14. Proton radiographic and numerical of colliding, diverging PBX-9502 detonations.

    SciTech Connect

    Mader, Charles L.; Zumbro, J. D.; Ferm, E. N.

    2002-01-01

    The Proton radiographic shot PRAD0077 was designed to study the interaction of colliding, diverging PBX-9502 detonations. The shot consisted of a 50 mm by 50 mm cylinder of PBX-9502 initiated on the top and bottom at the axis by a SE-1 detonator and a 12 mm by 12 mm cylinder of 9407. Seven radiographs were taken at times before and after the detonation collision. The system was modeled using the one-dimensional SIN code with C-J Burn in plane and spherically diverging geometry and using the two-dimensional TDL code with C-J Burn and Forest Fire. The system was also modeled with the recently developed AMR Eulerian reactive hydrodynamic code called NOBEL using Forest Fire. The system results in a large dead or nonreactive zone as the detonation attempts to turn the corner which is described by the model using Forest Fire. The peak detonation pressure achieved by the colliding diverging detonation is 50 gpa and density of 3.125 mg/ml which is about the same as that achieved by one-dimensional spherically diverging 9502 detonations but less than the one-dimensional plane 9502 peak colliding detonation pressure of 65 gpa and density of 3.4 mg/ml. The detonation travels for over 10 mm before it starts to expand and turn the corner leaving more than half of the explosive unreacted. The resulting diverging detonation is more curved than a one-dimensional spherical diverging detonation and has a steeper slope behind the detonation front. This results in the colliding pressure decaying faster than one-dimensional colliding spherical diverging pressures decay. The calculations using Forest Fire reproduce the major features of the radiograph and can be used to infer the colliding detonation characteristics.

  15. Retuning the DARHT Axis-II Linear Induction Accelerator

    SciTech Connect

    Ekdahl, Carl August Jr.; Schulze, Martin E.; Carlson, Carl A.; Frayer, Daniel K.

    2015-03-31

    The Dual-Axis Radiographic Hydrodynamic Test (DARHT) facility uses bremsstrahlung radiation source spots produced by the focused electron beams from two linear induction accelerators (LIAs) to radiograph large hydrodynamic experiments driven by high explosives. The Axis-II 1.7-kA, 1600-ns beam pulse is transported through the LIA by the magnetic field from 91 solenoids as it is accelerated to ~16.5 MeV. The magnetic field produced by the solenoids and 80 steering dipole pairs for a given set of magnet currents is known as the “tune” of the accelerator [1]. From June, 2013 through September, 2014 a single tune was used. This tune was based on measurements of LIA element positions made over several years [2], and models of solenoidal fields derived from actual field measurements [3] [4]. Based on the focus scan technique, changing the tune of the accelerator and downstream transport had no effect on the beam emittance, to within the uncertainties of the measurement. Beam sizes appear to have been overestimated in all prior measurements because of the low magnification of the imaging system. This has resulted in overestimates of emittance by ~50%. The high magnification imaging should be repeated with the old tune for direct comparison with the new tune. High magnification imaging with the new accelerator tune should be repeated after retuning the downstream to produce a much more symmetric beam to reduce the uncertainty of this measurement. Thus, these results should be considered preliminary until we can effect a new tune to produce symmetric spots at our imaging station, for high magnification images.

  16. Diode magnetic-field influence on radiographic spot size

    SciTech Connect

    Ekdahl, Carl A. Jr.

    2012-09-04

    Flash radiography of hydrodynamic experiments driven by high explosives is a well-known diagnostic technique in use at many laboratories. The Dual-Axis Radiography for Hydrodynamic Testing (DARHT) facility at Los Alamos was developed for flash radiography of large hydrodynamic experiments. Two linear induction accelerators (LIAs) produce the bremsstrahlung radiographic source spots for orthogonal views of each experiment ('hydrotest'). The 2-kA, 20-MeV Axis-I LIA creates a single 60-ns radiography pulse. For time resolution of the hydrotest dynamics, the 1.7-kA, 16.5-MeV Axis-II LIA creates up to four radiography pulses by slicing them out of a longer pulse that has a 1.6-{micro}s flattop. Both axes now routinely produce radiographic source spot sizes having full-width at half-maximum (FWHM) less than 1 mm. To further improve on the radiographic resolution, one must consider the major factors influencing the spot size: (1) Beam convergence at the final focus; (2) Beam emittance; (3) Beam canonical angular momentum; (4) Beam-motion blur; and (5) Beam-target interactions. Beam emittance growth and motion in the accelerators have been addressed by careful tuning. Defocusing by beam-target interactions has been minimized through tuning of the final focus solenoid for optimum convergence and other means. Finally, the beam canonical angular momentum is minimized by using a 'shielded source' of electrons. An ideal shielded source creates the beam in a region where the axial magnetic field is zero, thus the canonical momentum zero, since the beam is born with no mechanical angular momentum. It then follows from Busch's conservation theorem that the canonical angular momentum is minimized at the target, at least in principal. In the DARHT accelerators, the axial magnetic field at the cathode is minmized by using a 'bucking coil' solenoid with reverse polarity to cancel out whatever solenoidal beam transport field exists there. This is imperfect in practice, because of

  17. Hydrodynamic Hunters.

    PubMed

    Jashnsaz, Hossein; Al Juboori, Mohammed; Weistuch, Corey; Miller, Nicholas; Nguyen, Tyler; Meyerhoff, Viktoria; McCoy, Bryan; Perkins, Stephanie; Wallgren, Ross; Ray, Bruce D; Tsekouras, Konstantinos; Anderson, Gregory G; Pressé, Steve

    2017-03-28

    The Gram-negative Bdellovibrio bacteriovorus (BV) is a model bacterial predator that hunts other bacteria and may serve as a living antibiotic. Despite over 50 years since its discovery, it is suggested that BV probably collides into its prey at random. It remains unclear to what degree, if any, BV uses chemical cues to target its prey. The targeted search problem by the predator for its prey in three dimensions is a difficult problem: it requires the predator to sensitively detect prey and forecast its mobile prey's future position on the basis of previously detected signal. Here instead we find that rather than chemically detecting prey, hydrodynamics forces BV into regions high in prey density, thereby improving its odds of a chance collision with prey and ultimately reducing BV's search space for prey. We do so by showing that BV's dynamics are strongly influenced by self-generated hydrodynamic flow fields forcing BV onto surfaces and, for large enough defects on surfaces, forcing BV in orbital motion around these defects. Key experimental controls and calculations recapitulate the hydrodynamic origin of these behaviors. While BV's prey (Escherichia coli) are too small to trap BV in hydrodynamic orbit, the prey are also susceptible to their own hydrodynamic fields, substantially confining them to surfaces and defects where mobile predator and prey density is now dramatically enhanced. Colocalization, driven by hydrodynamics, ultimately reduces BV's search space for prey from three to two dimensions (on surfaces) even down to a single dimension (around defects). We conclude that BV's search for individual prey remains random, as suggested in the literature, but confined, however-by generic hydrodynamic forces-to reduced dimensionality.

  18. Radiographic diagnosis of diaphragmatic hernia: review of 60 cases in dogs and cats.

    PubMed

    Hyun, Changbaig

    2004-06-01

    Sixty cases of diaphragmatic hernia in dogs and cats were radiologically reviewed and categorized by their characteristic radiographic signs. Any particular predilection for age, sex, or breed was not observed. Liver, stomach and small intestine were more commonly herniated. At least two radiographs, at different angles, were required for a valid diagnosis, because some radiographic signs were not visible in a single radiographic view and more clearly detectable in two radiographic views. In addition to previously reported radiographic signs for diaphragmatic hernia, we found that the location of the stomach axis and the displacement of tracheal and bronchial segments were also useful radiographic signs.

  19. Using the Anatomical Axis as an Alternative to the Mechanical Axis to Assess Knee Alignment.

    PubMed

    Tipton, Shane C; Sutherland, John; Schwarzkopf, Ran

    2015-12-01

    The treatment of knee osteoarthritis and the preparation for total knee arthroplasty require repetitive imaging to guide preoperative planning and operative technique. Full-length standing anteroposterior images are the gold standard in assessing the alignment of the limb via the measurement of the mechanical axis of the knee. The anatomical axis can be obtained from a more limited image of the knee, and as such is less expensive and exposes the patient to less ionizing radiation. The objective of this cross-sectional prospective study was to examine the extent to which the anatomical axis measured on a fixed-flexed posteroanterior (Rosenberg view) radiograph correlates with the mechanical axis. The data of 209 total knee arthroplasty radiographs were analyzed to compare the preoperative correlation between the mechanical and anatomical axis. The anatomical axis correlated with the mechanical axis when it was measured from both the standing full-length anteroposterior radiograph and from a fixed-flexed posteroanterior radiograph. Using an angle of offset found from linear regression, these correlations become closer. Body mass index and Kellgren-Lawrence grade were not found to have a significant effect. It is the conclusion of this study that the anatomical axis, as measured from a limited knee radiography, may serve as a plausible estimate of the mechanical axis when done with a neutral angle of offset, and that offset angle depends on gender and the imaging technique used to determine the anatomical axis.

  20. Ship Hydrodynamics

    ERIC Educational Resources Information Center

    Lafrance, Pierre

    1978-01-01

    Explores in a non-mathematical treatment some of the hydrodynamical phenomena and forces that affect the operation of ships, especially at high speeds. Discusses the major components of ship resistance such as the different types of drags and ways to reduce them and how to apply those principles for the hovercraft. (GA)

  1. Ship Hydrodynamics

    ERIC Educational Resources Information Center

    Lafrance, Pierre

    1978-01-01

    Explores in a non-mathematical treatment some of the hydrodynamical phenomena and forces that affect the operation of ships, especially at high speeds. Discusses the major components of ship resistance such as the different types of drags and ways to reduce them and how to apply those principles for the hovercraft. (GA)

  2. Recent development of hydrodynamic modeling

    NASA Astrophysics Data System (ADS)

    Hirano, Tetsufumi

    2014-09-01

    In this talk, I give an overview of recent development in hydrodynamic modeling of high-energy nuclear collisions. First, I briefly discuss about current situation of hydrodynamic modeling by showing results from the integrated dynamical approach in which Monte-Carlo calculation of initial conditions, quark-gluon fluid dynamics and hadronic cascading are combined. In particular, I focus on rescattering effects of strange hadrons on final observables. Next I highlight three topics in recent development in hydrodynamic modeling. These include (1) medium response to jet propagation in di-jet asymmetric events, (2) causal hydrodynamic fluctuation and its application to Bjorken expansion and (3) chiral magnetic wave from anomalous hydrodynamic simulations. (1) Recent CMS data suggest the existence of QGP response to propagation of jets. To investigate this phenomenon, we solve hydrodynamic equations with source term which exhibits deposition of energy and momentum from jets. We find a large number of low momentum particles are emitted at large angle from jet axis. This gives a novel interpretation of the CMS data. (2) It has been claimed that a matter created even in p-p/p-A collisions may behave like a fluid. However, fluctuation effects would be important in such a small system. We formulate relativistic fluctuating hydrodynamics and apply it to Bjorken expansion. We found the final multiplicity fluctuates around the mean value even if initial condition is fixed. This effect is relatively important in peripheral A-A collisions and p-p/p-A collisions. (3) Anomalous transport of the quark-gluon fluid is predicted when extremely high magnetic field is applied. We investigate this possibility by solving anomalous hydrodynamic equations. We found the difference of the elliptic flow parameter between positive and negative particles appears due to the chiral magnetic wave. Finally, I provide some personal perspective of hydrodynamic modeling of high energy nuclear collisions

  3. Radiation Hydrodynamics

    SciTech Connect

    Castor, J I

    2003-10-16

    The discipline of radiation hydrodynamics is the branch of hydrodynamics in which the moving fluid absorbs and emits electromagnetic radiation, and in so doing modifies its dynamical behavior. That is, the net gain or loss of energy by parcels of the fluid material through absorption or emission of radiation are sufficient to change the pressure of the material, and therefore change its motion; alternatively, the net momentum exchange between radiation and matter may alter the motion of the matter directly. Ignoring the radiation contributions to energy and momentum will give a wrong prediction of the hydrodynamic motion when the correct description is radiation hydrodynamics. Of course, there are circumstances when a large quantity of radiation is present, yet can be ignored without causing the model to be in error. This happens when radiation from an exterior source streams through the problem, but the latter is so transparent that the energy and momentum coupling is negligible. Everything we say about radiation hydrodynamics applies equally well to neutrinos and photons (apart from the Einstein relations, specific to bosons), but in almost every area of astrophysics neutrino hydrodynamics is ignored, simply because the systems are exceedingly transparent to neutrinos, even though the energy flux in neutrinos may be substantial. Another place where we can do ''radiation hydrodynamics'' without using any sophisticated theory is deep within stars or other bodies, where the material is so opaque to the radiation that the mean free path of photons is entirely negligible compared with the size of the system, the distance over which any fluid quantity varies, and so on. In this case we can suppose that the radiation is in equilibrium with the matter locally, and its energy, pressure and momentum can be lumped in with those of the rest of the fluid. That is, it is no more necessary to distinguish photons from atoms, nuclei and electrons, than it is to distinguish

  4. Robotic real-time radiographic inspection system

    SciTech Connect

    McNair, J.

    1987-01-01

    A computer-controlled real-time radiographic system with remote robotic material handling has been developed and installed at the US Army's Yuma Proving Ground. This system is used for the nondestructive examination of a variety of munition types tested at the proving ground. This paper describes the system and its capabilities. The system consists of an overhead robot for material handling, a five-axis manipulator for positioning the item being inspected, and the real-time radiographic image acquisition and analysis equipment. The system is fully automated and uses a single minicomputer as the system controller.

  5. Bacterial Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Lauga, Eric

    2016-01-01

    Bacteria predate plants and animals by billions of years. Today, they are the world's smallest cells, yet they represent the bulk of the world's biomass and the main reservoir of nutrients for higher organisms. Most bacteria can move on their own, and the majority of motile bacteria are able to swim in viscous fluids using slender helical appendages called flagella. Low-Reynolds number hydrodynamics is at the heart of the ability of flagella to generate propulsion at the micrometer scale. In fact, fluid dynamic forces impact many aspects of bacteriology, ranging from the ability of cells to reorient and search their surroundings to their interactions within mechanically and chemically complex environments. Using hydrodynamics as an organizing framework, I review the biomechanics of bacterial motility and look ahead to future challenges.

  6. Quantum hydrodynamics

    NASA Astrophysics Data System (ADS)

    Tsubota, Makoto; Kobayashi, Michikazu; Takeuchi, Hiromitsu

    2013-01-01

    Quantum hydrodynamics in superfluid helium and atomic Bose-Einstein condensates (BECs) has been recently one of the most important topics in low temperature physics. In these systems, a macroscopic wave function (order parameter) appears because of Bose-Einstein condensation, which creates quantized vortices. Turbulence consisting of quantized vortices is called quantum turbulence (QT). The study of quantized vortices and QT has increased in intensity for two reasons. The first is that recent studies of QT are considerably advanced over older studies, which were chiefly limited to thermal counterflow in 4He, which has no analog with classical traditional turbulence, whereas new studies on QT are focused on a comparison between QT and classical turbulence. The second reason is the realization of atomic BECs in 1995, for which modern optical techniques enable the direct control and visualization of the condensate and can even change the interaction; such direct control is impossible in other quantum condensates like superfluid helium and superconductors. Our group has made many important theoretical and numerical contributions to the field of quantum hydrodynamics of both superfluid helium and atomic BECs. In this article, we review some of the important topics in detail. The topics of quantum hydrodynamics are diverse, so we have not attempted to cover all these topics in this article. We also ensure that the scope of this article does not overlap with our recent review article (arXiv:1004.5458), “Quantized vortices in superfluid helium and atomic Bose-Einstein condensates”, and other review articles.

  7. Visual simulation of radiographs

    SciTech Connect

    Laguna, G.

    1985-01-18

    A method for computer simulation of radiographs has been added to the LLNL version of the solid modeler TIPS-1 (Technical Information Processing System-1). This new tool will enable an engineer to compare an actual radiograph of a solid to its computer-generated counterpart. The appearance of discrepancies between the two can be an indication of flaws in the solid object. Simulated radiographs can also be used to preview the placement of x-ray sources to focus on areas of concern before actual radiographs are made.

  8. A comparative assessment of alternatives to the full-leg radiograph for determining knee joint alignment

    PubMed Central

    2012-01-01

    Background The purpose of this study was to assess the concurrent validity of alternative measures of frontal plane knee alignment, namely the radiographic anatomic axis and two clinical measures in patients complaining of knee malalignment as compared with the mechanical axis on full-length radiograph of lower limbs. Methods The knee-alignment angle was measured in 100 knees of 50 subjects with the chief complaint of frontal knee malalignment according to the following methods: lower-limb mechanical axis on radiograph, lower-limb anatomic axis on radiograph, distance between medial femoral condyles or medial malleoli using a calliper and lower-limb alignment using a goniometer. Data were analyzed using Pearson’s correlation coefficient and simple linear regression. Results The anatomic axis best correlated with the mechanical axis (r = 0.93, P<0.001), followed closely by the intercondylar/intermalleolar distance measured by calliper (r = 0.89, P<0.001). Significant correlation was also found between the mechanical-axis angle and the lower limb axis measured by goniometer (r = 0.67, P<0.001). Conclusions The anatomic axis on radiograph, the calliper method and to a lesser extent the goniometer measurement appear to be valid alternatives to the mechanical axis on full-leg radiograph for determining frontal plane knee alignment. These alternative measures have the potential to provide useful information regarding knee alignment and may increase the assessment of this parameter by clinicians and researchers. PMID:23110745

  9. Applied pathology for radiographers

    SciTech Connect

    Laudicina, P.

    1987-01-01

    This book presents a basic text for the student of radiologic sciences. It includes most of the pathology recommended by the ASRT Curriculum Guide. Radiographic technique and positioning are examined when relevant to obtaining quality radiographs of specific disease conditions. Brief overviews of these conditions include background etiology, diagnosis, treatment and prognosis. Many illustrations are included to enhance understanding.

  10. Radiographic film package

    SciTech Connect

    Muylle, W. E.

    1985-08-27

    A radiographic film package for non-destructive testing, comprising a radiographic film sheet, an intensifying screen with a layer of lead bonded to a paper foil, and a vacuum heat-sealed wrapper with a layer of aluminum and a heat-sealed easy-peelable thermoplastic layer.

  11. RF generation in the DARHT Axis-II beam dump

    SciTech Connect

    Ekdahl, Carl A. Jr.

    2012-05-03

    We have occasionally observed radio-frequency (RF) electromagnetic signals in the downstream transport (DST) of the second axis linear induction accelerator (LIA) at the dual-axis radiographic hydrodynamic testing (DARHT) facility. We have identified and eliminated some of the sources by eliminating the offending cavities. However, we still observe strong RF in the range 1 GHz t0 2 GHz occurring late in the {approx}2-{micro}s pulse that can be excited or prevented by varying the downstream tune. The narrow frequency width (<0.5%) and near exponential growth at the dominant frequency is indicative of a beam-cavity interaction, and electro-magnetic simulations of cavity structure show a spectrum rich in resonances in the observed frequency range. However, the source of beam produced RF in the cavity resonance frequency range has not been identified, and it has been the subject of much speculation, ranging from beam-plasma or beam-ion instabilities to unstable cavity coupling.

  12. Hydrodynamic supercontinuum.

    PubMed

    Chabchoub, A; Hoffmann, N; Onorato, M; Genty, G; Dudley, J M; Akhmediev, N

    2013-08-02

    We report the experimental observation of multi-bound-soliton solutions of the nonlinear Schrödinger equation (NLS) in the context of hydrodynamic surface gravity waves. Higher-order N-soliton solutions with N=2, 3 are studied in detail and shown to be associated with self-focusing in the wave group dynamics and the generation of a steep localized carrier wave underneath the group envelope. We also show that for larger input soliton numbers, the wave group experiences irreversible spectral broadening, which we refer to as a hydrodynamic supercontinuum by analogy with optics. This process is shown to be associated with the fission of the initial multisoliton into individual fundamental solitons due to higher-order nonlinear perturbations to the NLS. Numerical simulations using an extended NLS model described by the modified nonlinear Schrödinger equation, show excellent agreement with experiment and highlight the universal role that higher-order nonlinear perturbations to the NLS play in supercontinuum generation.

  13. Hydrocyclone separation hydrodynamics

    SciTech Connect

    Ivanov, A.A.; Ruzanov, S.R.; Lunyushkina, I.A.

    1987-10-20

    The lack of an adequate hydrodynamic model for a hydrocyclone has so far been the main obstacle to devising a general method for designing such apparatus. The authors present a method of calculating the liquid flow in the working zone. The results have been used to calculate the separating power in application to dilute suspensions. The Navier-Stokes equations and the equation of continuity are used in examining the behavior together with assumptions based on experiment: the conditions for stationary axisymmetric flow, constant turbulent viscosity, and a constant radial profile for the tangential low speed at all the heights. The boundary conditions are those for liquid slip at the side walls and absence of vortex drainage at the axis. The results enable one to choose the dimensions for particular separations.

  14. Synchronization and hydrodynamic interactions

    NASA Astrophysics Data System (ADS)

    Powers, Thomas; Qian, Bian; Breuer, Kenneth

    2008-03-01

    Cilia and flagella commonly beat in a coordinated manner. Examples include the flagella that Volvox colonies use to move, the cilia that sweep foreign particles up out of the human airway, and the nodal cilia that set up the flow that determines the left-right axis in developing vertebrate embryos. In this talk we present an experimental study of how hydrodynamic interactions can lead to coordination in a simple idealized system: two nearby paddles driven with fixed torques in a highly viscous fluid. The paddles attain a synchronized state in which they rotate together with a phase difference of 90 degrees. We discuss how synchronization depends on system parameters and present numerical calculations using the method of regularized stokeslets.

  15. Chromatin hydrodynamics.

    PubMed

    Bruinsma, Robijn; Grosberg, Alexander Y; Rabin, Yitzhak; Zidovska, Alexandra

    2014-05-06

    Following recent observations of large scale correlated motion of chromatin inside the nuclei of live differentiated cells, we present a hydrodynamic theory-the two-fluid model-in which the content of a nucleus is described as a chromatin solution with the nucleoplasm playing the role of the solvent and the chromatin fiber that of a solute. This system is subject to both passive thermal fluctuations and active scalar and vector events that are associated with free energy consumption, such as ATP hydrolysis. Scalar events drive the longitudinal viscoelastic modes (where the chromatin fiber moves relative to the solvent) while vector events generate the transverse modes (where the chromatin fiber moves together with the solvent). Using linear response methods, we derive explicit expressions for the response functions that connect the chromatin density and velocity correlation functions to the corresponding correlation functions of the active sources and the complex viscoelastic moduli of the chromatin solution. We then derive general expressions for the flow spectral density of the chromatin velocity field. We use the theory to analyze experimental results recently obtained by one of the present authors and her co-workers. We find that the time dependence of the experimental data for both native and ATP-depleted chromatin can be well-fitted using a simple model-the Maxwell fluid-for the complex modulus, although there is some discrepancy in terms of the wavevector dependence. Thermal fluctuations of ATP-depleted cells are predominantly longitudinal. ATP-active cells exhibit intense transverse long wavelength velocity fluctuations driven by force dipoles. Fluctuations with wavenumbers larger than a few inverse microns are dominated by concentration fluctuations with the same spectrum as thermal fluctuations but with increased intensity.

  16. Radiographic Reference Points Are Inaccurate With and Without a True Lateral Radiograph: The Importance of Anatomy in Medial Patellofemoral Ligament Reconstruction.

    PubMed

    Ziegler, Connor G; Fulkerson, John P; Edgar, Cory

    2016-01-01

    Studies have reported methods for radiographically delineating medial patellofemoral ligament (MPFL) femoral tunnel position on a true lateral knee radiograph. However, obtaining a true lateral fluoroscopic radiograph intraoperatively can be challenging, rendering radiographic methods for tunnel positioning potentially inaccurate. To quantify the magnitude of MPFL femoral tunnel malposition that occurs on true lateral and aberrant lateral knee radiographs when using a previously reported radiographic technique for MPFL femoral tunnel localization. Descriptive laboratory study. Ten fresh-frozen cadaveric knees were dissected to expose the MPFL femoral insertion and surrounding medial knee anatomy. True lateral and aberrant lateral knee radiographs at 2.5°, 5°, and 10° off-axis were obtained with a standard mini C-arm in 4 orientations: anterior to posterior, posterior to anterior, caudal, and cephalad. A previously reported radiographic method for MPFL femoral localization was performed on all radiographs and compared in reference to the anatomic MPFL attachment center. The radiographic point, as previously described, was a mean distance of 4.1 mm from the anatomic MPFL attachment on a true lateral knee radiograph. The distance between the anatomic MPFL attachment center and the radiographic point significantly increased on aberrant lateral knee radiographs with as little as 5° of rotational error in 3 of 4 orientations of rotation when a standard mini C-arm was used. This corresponded to a malposition of 7.5, 9.2, and 8.1 mm on 5°-aberrant radiographs in the anterior-posterior, posterior-anterior, and cephalad orientations, respectively (P < .005). In the same 3 orientations of rotation, MPFL tunnel malposition on the femur exceeded 5 mm on 2.5° aberrant radiographs. The commonly utilized radiographic point, as previously described for MPFL femoral tunnel placement, results in inaccurate tunnel localization on a true lateral radiograph, and this inaccuracy is

  17. Weld radiograph enigmas

    NASA Technical Reports Server (NTRS)

    Jemian, Wartan A.

    1986-01-01

    Weld radiograph enigmas are features observed on X-ray radiographs of welds. Some of these features resemble indications of weld defects, although their origin is different. Since they are not understood, they are a source of concern. There is a need to identify their causes and especially to measure their effect on weld mechanical properties. A method is proposed whereby the enigmas can be evaluated and rated, in relation to the full spectrum of weld radiograph indications. Thie method involves a signature and a magnitude that can be used as a quantitive parameter. The signature is generated as the diference between the microdensitometer trace across the radiograph and the computed film intensity derived from a thickness scan along the corresponding region of the sample. The magnitude is the measured difference in intensity between the peak and base line values of the signature. The procedure is demonstated by comparing traces across radiographs of a weld sample before and after the introduction of a hole and by a system based on a MacIntosh mouse used for surface profiling.

  18. Comparison Of Digital Radiographic Units

    NASA Astrophysics Data System (ADS)

    Wang, Yen

    1986-06-01

    A total PACS will be inevitable for radiology practice within several years. To achieve a total PACS for radiology, a satisfactory digital radiographic unit is required, because approximately 65% of digital data for PACS comes from digital radiographs. There are several possibilities for producing digital radiographs, and 3 - 4 companies have been marketing digital radiographic devices. Some data regarding the digital radiographic units on the market are compared. It will aid in assessing the current status and availability of this aspect of development, as well as providing a summary of further development of digital radiographic technology.

  19. Neutron radiographic viewing system

    NASA Technical Reports Server (NTRS)

    Leysath, W.; Brown, R. L.

    1972-01-01

    Neutron radiographic viewing system consisting of camera head and control processor is developed for use in nondestructive testing applications. Camera head consists of neutron-sensitive image intensifier system, power supply, and SEC vidicon camera head. Both systems, with their optics, are housed on test mount.

  20. Holography and hydrodynamics in small systems

    NASA Astrophysics Data System (ADS)

    Chesler, Paul M.

    2016-12-01

    Using holographic duality, we present results for the off-center collision of Gaussian wave packets in strongly coupled N = 4 supersymmetric Yang-Mills theory. The wave packets are thin along the collision axis and superficially at least resemble Lorentz contracted colliding protons. The collision results in the formation of a droplet of liquid of size R ∼ 1 /Teff where Teff is the effective temperature, which is the characteristic microscopic scale in strongly coupled plasma. These results demonstrate the applicability of hydrodynamics to microscopically small systems and bolster the notion that hydrodynamics can be applied to heavy-light ion collisions as well as proton-proton collisions.

  1. Neutron radiographic viewing system

    NASA Technical Reports Server (NTRS)

    1972-01-01

    The design, development and application of a neutron radiographic viewing system for use in nondestructive testing applications is considered. The system consists of a SEC vidicon camera, neutron image intensifier system, disc recorder, and TV readout. Neutron bombardment of the subject is recorded by an image converter and passed through an optical system into the SEC vidicon. The vidicon output may be stored, or processed for visual readout.

  2. Large Format Radiographic Imaging

    SciTech Connect

    J. S. Rohrer; Lacey Stewart; M. D. Wilke; N. S. King; S. A Baker; Wilfred Lewis

    1999-08-01

    Radiographic imaging continues to be a key diagnostic in many areas at Los Alamos National Laboratory (LANL). Radiographic recording systems have taken on many form, from high repetition-rate, gated systems to film recording and storage phosphors. Some systems are designed for synchronization to an accelerator while others may be single shot or may record a frame sequence in a dynamic radiography experiment. While film recording remains a reliable standby in the radiographic community, there is growing interest in investigating electronic recording for many applications. The advantages of real time access to remote data acquisition are highly attractive. Cooled CCD camera systems are capable of providing greater sensitivity with improved signal-to-noise ratio. This paper begins with a review of performance characteristics of the Bechtel Nevada large format imaging system, a gated system capable of viewing scintillators up to 300 mm in diameter. We then examine configuration alternatives in lens coupled and fiber optically coupled electro-optical recording systems. Areas of investigation include tradeoffs between fiber optic and lens coupling, methods of image magnification, and spectral matching from scintillator to CCD camera. Key performance features discussed include field of view, resolution, sensitivity, dynamic range, and system noise characteristics.

  3. DARHT Radiographic Grid Scale Correction

    SciTech Connect

    Warthen, Barry J.

    2015-02-13

    Recently it became apparent that the radiographic grid which has been used to calibrate the dimensional scale of DARHT radiographs was not centered at the location where the objects have been centered. This offset produced an error of 0.188% in the dimensional scaling of the radiographic images processed using the assumption that the grid and objects had the same center. This paper will show the derivation of the scaling correction, explain how new radiographs are being processed to account for the difference in location, and provide the details of how to correct radiographic image processed with the erroneous scale factor.

  4. Computer enhancement of radiographs

    NASA Technical Reports Server (NTRS)

    Dekaney, A.; Keane, J.; Desautels, J.

    1973-01-01

    Examination of three relevant noise processes and the image degradation associated with Marshall Space Flight Center's (MSFC) X-ray/scanning system was conducted for application to computer enhancement of radiographs using MSFC's digital filtering techniques. Graininess of type M, R single coat and R double coat X-ray films was quantified as a function of density level using root-mean-square (RMS) granularity. Quantum mottle (including film grain) was quantified as a function of the above film types, exposure level, specimen material and thickness, and film density using RMS granularity and power spectral density (PSD). For various neutral-density levels the scanning device used in digital conversion of radiographs was examined for noise characteristics which were quantified by RMS granularity and PSD. Image degradation of the entire pre-enhancement system (MG-150 X-ray device; film; and optronics scanner) was measured using edge targets to generate modulation transfer functions (MTF). The four parameters were examined as a function of scanning aperture sizes of approximately 12.5 25 and 50 microns.

  5. Reliability and Lifetime Testing of the DARHT Second AxisInduction Cells

    SciTech Connect

    Waldron, W.L.; Nielsen, K.E.; Spence, P.W.

    2005-06-30

    The Dual-Axis Radiographic Hydrodynamics Test (DARHT) facility will employ two perpendicular electron linear induction accelerators to produce intense, bremsstrahlung x-ray pulses for flash radiography. The second axis, DARHT II, features a 3 MeV injector and a 15 MeV, 2 kA, 1.5 {micro}s accelerator consisting of 74 induction cells and drivers. High reliability and lifetime of the induction cells are major requirements because of the cost of execution of hydro tests and because the time and effort to remove and refurbish a failed cell is considerable. Research and development efforts have identified problems in the original cell design and means to upgrade the design, performance, and reliability of the linear induction cells. Physical changes in the cell oil region, the cell vacuum region, and the cell drivers, together with different operational and maintenance procedures, have been implemented in six prototype units. This paper addresses the acceptance criteria and acceptance tests applied to the prototype accelerator cells. These tests validate the upgraded cell design and demonstrate that it meets the essential electrical and reliability requirements prior to committing to refurbishment of the full ensemble of DARHT II cells. The prototype acceptance test results are presented and discussed in terms of the confidence level in which the required cell lifetime and reliability are met by the upgraded design and modified operation and maintenance procedures.

  6. A simplified method to determine acetabular cup anteversion from plain radiographs.

    PubMed

    Widmer, Karl-Heinz

    2004-04-01

    Plain radiographs are the most important diagnostic means for determining the indication and following up on total hip arthroplasty. The acetabular cup position can be easily determined by applying trigonometric functions. This report presents an even simpler method. The short axis of the projected ellipse is measured and related to the total cross-section of the projected cup along the short axis. This relationship correlates with acetabular cup anteversion angles and represents an inverse sinus function. A close linear correlation is seen within the most common interval from 10 degrees to 30 degrees. Anteversion is between 23 degrees to 24 degrees when the ellipse bisects the total acetabular cross-section. This means that simply measuring the length of the short ellipse axis and the total length of the projected cross-section along the short axis provides the radiographic acetabular anteversion. Nonorthogonal projected radiographs should be corrected first.

  7. HYDRODYNAMIC COMPRESSIVE FORGING.

    DTIC Science & Technology

    HYDRODYNAMICS), (*FORGING, COMPRESSIVE PROPERTIES, LUBRICANTS, PERFORMANCE(ENGINEERING), DIES, TENSILE PROPERTIES, MOLYBDENUM ALLOYS , STRAIN...MECHANICS), BERYLLIUM ALLOYS , NICKEL ALLOYS , CASTING ALLOYS , PRESSURE, FAILURE(MECHANICS).

  8. Transverse axis fluid turbine

    SciTech Connect

    Brenneman, B.

    1983-11-15

    A fluid turbine, the rotation axis of which is transverse to the direction of fluid flow, has at least two blade assemblies mounted for rotation about the rotation axis. Each blade assembly includes a streamlined elongated blade having a span parallel to the rotation axis. Each blade is pivotable about a pivot axis parallel to and spaced from the rotation axis. The pivot axis is located circumferentially ahead of the blade center of pressure with respect to the direction of turbine rotation. Each blade assembly is so constructed that its center of mass is located either at its pivot axis or circumferentially at its pivot axis and radially outboard of its pivot axis.

  9. Dynamic Radiographic Imaging

    SciTech Connect

    Volkov, A.; Turley, D.; Veeser, L.; Lukyanov, N.; Yegorov, N.; Baker, S.A.; Mirenko, V.; Lewis, W.; Kuropatkin, Y.

    1999-06-01

    A radiographic system recently developed by American and Russian collaborators is designed to capture multiple images of a dynamic event lasting less than 10 microseconds. Various optical and electro-optical components were considered and their performance compared. The final system employed a solid crystal of lutetium oxyorthosilicate doped with cerium (LSO:Ce or LSO) for X-ray-to-light conversion with a coherent fiber optic bundle to relay the scintillator image to a streak camera with charge coupled device (CCD) readout. Resolution and sensitivity studies were carried out for this system on two different sources of X-rays: a 20 MeV microtron and a 70 MeV betatron.

  10. Textbook of radiographic science

    SciTech Connect

    Bentley, H.B.

    1987-01-01

    This book has been written to provide an outline of scientific background of specialized radiologic procedures for candidates studying for the higher examination of the College of Radiographers (United Kingdom). The book contains nine chapters on various areas such as emergency/trauma; pediatrics; neurologic, angiographic, and urodynamic studies; and a final chapter on research. An index concludes the book. Information on historical and scientific procedural background, equipment, anatomic and pathologic correlates, and positioning of the patient is organized and presented. Scientific data are inserted in the text where appropriate. Metrizamide is given an extensive write-up as the contrast medium of choice for imaging of the spinal cord and is said to be ''less toxic than other forms of water-soluble contrast.''

  11. Radiographic Assessment for Back Pain

    MedlinePlus

    ... When Should I get an X-ray for Low Back Pain? Other Reasons for Having an X-ray What ... rays? What are Radiographic Assessments? Radiographic assessments for low back pain involve the use of X-rays to determine ...

  12. Oral tuberculosis: unusual radiographic findings.

    PubMed

    Sansare, K; Gupta, A; Khanna, V; Karjodkar, F

    2011-05-01

    Oral tuberculosis and its radiographic findings are not commonly encountered in an oral and maxillofacial radiology practice. Literature has occasional mention of the radiographic findings of oral tuberculosis, which are still ambiguous. When affected, it is manifested majorly in the oral mucosa and rarely in the jaw bones. Here, we report certain unusual radiographic findings of oral tuberculosis which have been rarely mentioned in the literature. Four illustrative cases describe bony resorption, condylar resorption, resorption of the inferior border of the mandible and rarefaction of the alveolar bone as radiographic findings of oral tuberculosis. Follow up of the first case demonstrated regeneration of the condylar head after anti-Kochs therapy was completed, a hitherto unreported phenomenon. The importance of including tuberculosis in the differential diagnosis of some of the unusual radiographic manifestations is emphasized.

  13. Radiographic evaluation of hip implants.

    PubMed

    Chang, Connie Y; Huang, Ambrose J; Palmer, William E

    2015-02-01

    Serial radiographs are the mainstay in the longitudinal assessment of hip implants. The prosthesis, periprosthetic bone, and juxta-articular soft tissues are inspected for fracture, periosteal reaction, stress shielding, calcar resorption, osteolysis, bony remodeling, metallic debris, and heterotopic ossification. Comparison radiographs best confirm implant migration, subsidence, and aseptic loosening. Infection, particle disease, reaction to metal, and mechanical impingement are important causes of postsurgical pain, but in their earliest stages they may be difficult to diagnose using radiographs. This article addresses the role of radiography following hip arthroplasty. Thieme Medical Publishers 333 Seventh Avenue, New York, NY 10001, USA.

  14. Hydrodynamic effects in proteins.

    PubMed

    Szymczak, Piotr; Cieplak, Marek

    2011-01-26

    Experimental and numerical results pertaining to flow-induced effects in proteins are reviewed. Special emphasis is placed on shear-induced unfolding and on the role of solvent mediated hydrodynamic interactions in the conformational transitions in proteins.

  15. Scanning radiographic apparatus

    SciTech Connect

    Albert, R.D.

    1980-04-01

    Visual display of dental, medical or other radiographic images is realized with an x-ray tube in which an electron beam is scanned through an x-y raster pattern on a broad anode plate, the scanning being synchronized with the x-y sweep signals of a cathode ray tube display and the intensity signal for the display being derived from a small x-ray detector which receives x-rays that have passed through the subject to be imaged. Positioning and support of the detector are provided for by disposing the detector in a probe which may be attached to the x-ray tube at any of a plurality of different locations and by providing a plurality of such probes of different configuration in order to change focal length, to accommodate to different detector placements relative to the subject, to enhance patient comfort and to enable production of both periapical images and wider angle pantomographic images. High image definition with reduced radiation dosage is provided for by a lead glass collimator situated between the x-ray tube and subject and having a large number of spaced-apart minute radiation transmissive passages convergent on the position of the detector. Releasable mounting means enable changes of collimator in conjunction with changes of the probe to change focal length. A control circuit modifies the x-y sweep signals applied to the x-ray tube and modulates electron beam energy and current in order to correct for image distortions and other undesirable effects which can otherwise be present in a scanning x-ray system.

  16. Radiographic Assessment for Back Pain

    MedlinePlus

    ... in which he or she suspects congenital defects, degenerative disease, trauma, metastatic cancer or bone deformity as a ... ENGLISH Related Conditions/Treatments Exercise/Cervical Exercise Lumbar Degenerative Disc Disease NSAIDs Radiographic Assessment of Spinal Disorders Scoliosis Spinal ...

  17. Radiographic findings in liveborn triploidy.

    PubMed

    Silverthorn, K G; Houston, C S; Newman, D E; Wood, B J

    1989-01-01

    The detailed radiographic features of triploidy, a fatal congenital disorder with 69 chromosomes, have not previously been reported. Radiographs of ten liveborn infants with chromosomally confirmed triploidy showed six findings highly suggestive of this diagnosis: harlequin orbits, small anterior fontanelle, gracile ribs, diaphyseal overtubulation of long bones, upswept clavicles and antimongoloid pelvis. Sixteen other less specific findings showed many similarities to those found in trisomy 18.

  18. Film holder for radiographing tubing

    DOEpatents

    Davis, Earl V.; Foster, Billy E.

    1976-01-01

    A film cassette is provided which may be easily placed about tubing or piping and readily held in place while radiographic inspection is performed. A pair of precurved light-impervious semi-rigid plastic sheets, hinged at one edge, enclose sheet film together with any metallic foils or screens. Other edges are made light-tight with removable caps, and the entire unit is held securely about the object to be radiographed with a releasable fastener such as a strip of Velcro.

  19. Factors affecting radiographers' organizational commitment.

    PubMed

    Akroyd, Duane; Jackowski, Melissa B; Legg, Jeffrey S

    2007-01-01

    A variety of factors influence employees' attitudes toward their workplace and commitment to the organization that employs them. However, these factors have not been well documented among radiologic technologists. To determine the predictive ability of selected organizational, leadership, work-role and demographic variables on organizational commitment for a national sample of radiographers. Three thousand radiographers registered by the American Registry of Radiologic Technologists working full time in clinical settings were surveyed by mail regarding their commitment to their employers, leadership within the organization that employs them, employer support and demographic information. Overall, radiographers were found to have only a moderate level of commitment to their employers. Among the factors that significantly affected commitment were the radiographer's educational level, perceived level of organizational support, role clarity and organizational leadership. The results of this study could provide managers and supervisors with insights on how to empower and challenge radiographers and offer opportunities that will enhance radiographers' commitment to the organization, thus reducing costly turnover and improving employee performance.

  20. Improved radiographic outcomes with patient-specific total knee arthroplasty.

    PubMed

    Ivie, Conrad B; Probst, Patrick J; Bal, Amrit K; Stannard, James T; Crist, Brett D; Sonny Bal, B

    2014-11-01

    Patient-specific guides can improve limb alignment and implant positioning in total knee arthroplasty, although not all studies have supported this benefit. We compared the radiographs of 100 consecutively-performed patient-specific total knees to a similar group that was implanted with conventional instruments instead. The patient-specific group showed more accurate reproduction of the theoretically ideal mechanical axis, with fewer outliers, but implant positioning was comparable between groups. Our odds ratio comparison showed that the patient-specific group was 1.8 times more likely to be within the desired +3° from the neutral mechanical axis when compared to the standard control group. Our data suggest that reliable reproduction of the limb mechanical axis may accrue from patient-specific guides in total knee arthroplasty when compared to standard, intramedullary instrumentation.

  1. Radiographic testing at Lawrence Livermore National Laboratory

    SciTech Connect

    Bossi, R.H.

    1982-04-21

    Radiographic testing is a nondestructive inspection technique which uses penetrating radiation. The Nondestructive Evaluation (NDE) Section at Lawrence Livermore National Laboratory has a broad spectrum of equipment and techniques for radiographic testing. These resources include low-energy vacuum systems, low- and mid-energy cabinet and cell radiographic systems, high-energy linear accelerators, portable x-ray machines and radioisotopes for radiographic inspections. For diagnostic testing the NDE Section also has real-time and flash radiographic equipment.

  2. Radiographic prevalence of scaphotrapeziotrapezoid osteoarthrosis.

    PubMed

    Scordino, Laura E; Bernstein, Jenna; Nakashian, Michael; McIntosh, Masai; Cote, Mark P; Rodner, Craig M; Wolf, Jennifer Moriatis; Wolf, Jennifer Moraitis

    2014-09-01

    To define the radiographic prevalence of scaphotrapeziotrapezoid (STT) osteoarthrosis (OA) in a cohort of patients presenting to a hand surgeon for any complaint. The secondary purpose was to evaluate coexisting thumb carpometacarpal (CMC) joint OA. Seven hundred radiographs were evaluated for presence and degree of STT and thumb CMC arthritic changes in consecutive patients presenting to a hand clinic for any chief complaint over the study period. OA was noted at the STT joint in 111 of the 700 (16%) radiographs reviewed. Increased age, female sex, presence of a scapholunate (SL) ligament gap greater than 3 mm, and presence of radiographic thumb CMC joint OA were all significantly correlated with presence of STT joint OA. However, logistical regression analysis demonstrated that only increasing age, presence of an SL ligament gap greater than 3 mm, and presence of thumb CMC joint OA were strong predictors of STT joint OA. STT joint OA is a common finding on hand radiographs of patients presenting to a hand clinic. Its prevalence increases with age, the presence of an SL ligament gap greater than 3 mm, and with the presence of CMC joint OA. Diagnostic III. Copyright © 2014 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  3. Automating measurement from standard radiographs

    NASA Astrophysics Data System (ADS)

    Harris, Adam I.; Dori, Dov; Sheinkop, Mitchell; Berkson, Eric; Haralick, Robert M.

    1993-04-01

    An obligatory portion of orthopaedic examination is a radiographic examination. Techniques, such as computed tomography easily lend themselves to computerized analysis. Both expense and hazards from radiation prohibit their routine use in orthopaedic practice. Standard radiographs provide a significant amount of information for the orthopaedic surgeon. From the radiographs, surgeons will make many measurements and assessments. A major problem is that measurements are performed by hand and most often by the operating surgeon who may not be completely objective. To overcome this as well as to alleviate the burden of manual measurements which must be made by trained professionals, we have initiated a program to automate certain radiographic measurements. The technique involves digitizing standard radiographs from which features are extracted and identified. This poses a challenge. Structures, such as soft tissues (muscle, and bowel) markedly decrease the signal to noise ratio of the image. The work discusses modeling of the soft tissue structures in order to enhance detection and identification of bone landmarks. These are the anchors for standard measurements which in turn have clinical utility.

  4. Resurgence in extended hydrodynamics

    NASA Astrophysics Data System (ADS)

    Aniceto, Inês; Spaliński, Michał

    2016-04-01

    It has recently been understood that the hydrodynamic series generated by the Müller-Israel-Stewart theory is divergent and that this large-order behavior is consistent with the theory of resurgence. Furthermore, it was observed that the physical origin of this is the presence of a purely damped nonhydrodynamic mode. It is very interesting to ask whether this picture persists in cases where the spectrum of nonhydrodynamic modes is richer. We take the first step in this direction by considering the simplest hydrodynamic theory which, instead of the purely damped mode, contains a pair of nonhydrodynamic modes of complex conjugate frequencies. This mimics the pattern of black brane quasinormal modes which appear on the gravity side of the AdS/CFT description of N =4 supersymmetric Yang-Mills plasma. We find that the resulting hydrodynamic series is divergent in a way consistent with resurgence and precisely encodes information about the nonhydrodynamic modes of the theory.

  5. Hydrodynamic Vortex on Surfaces

    NASA Astrophysics Data System (ADS)

    Ragazzo, Clodoaldo Grotta; de Barros Viglioni, Humberto Henrique

    2017-04-01

    The equations of motion for a system of point vortices on an oriented Riemannian surface of finite topological type are presented. The equations are obtained from a Green's function on the surface. The uniqueness of the Green's function is established under hydrodynamic conditions at the surface's boundaries and ends. The hydrodynamic force on a point vortex is computed using a new weak formulation of Euler's equation adapted to the point vortex context. An analogy between the hydrodynamic force on a massive point vortex and the electromagnetic force on a massive electric charge is presented as well as the equations of motion for massive vortices. Any noncompact Riemann surface admits a unique Riemannian metric such that a single vortex in the surface does not move ("Steady Vortex Metric"). Some examples of surfaces with steady vortex metric isometrically embedded in R^3 are presented.

  6. Hydrodynamics of bacterial suspensions

    NASA Astrophysics Data System (ADS)

    Arlt, Jochen; Duncan, William J.; Poon, Wilson C. K.

    2005-08-01

    Suspensions of motile E. coli bacteria serve as a model system to experimentally study the hydrodynamics of active particle suspensions. Colloidal probe particles are localised within a suspension of motile bacteria by use of optical tweezers and their uctuations are monitored. The activity of the bacteria effects the fluctuations of the probe particles and their correlation, revealing information about the hydrodynamics of the suspension. We highlight experimental problems that make the interpretation of 'single probe' experiments (as reported before in literature) diffcult and present some preliminary results for 'dual probe' cross-correlation experiments.

  7. New View on the Initial Development Site and Radiographic Classification System of Osteoarthritis of the Knee Based on Radiographic Analysis

    PubMed Central

    Moon, Ki-Ho

    2012-01-01

    Introduction: Radiographic pathology of severe osteoarthritis of the knee (OAK) such as severe osteophyte at tibial spine (TS), compartment narrowing, marginal osteophyte, and subchondral sclerosis is well known. Kellgren-Lawrence grading system, which is widely used to diagnose OAK, describes narrowing-marginal osteophyte in 4-grades but uses osteophyte at TS only as evidence of OAK without detailed-grading. However, kinematically the knee employs medial TS as an axis while medial and lateral compartments carry the load, suggesting that early OAK would occur sooner at TS than at compartment. Then, Kellgren-Lawrence system may be inadequate to diagnose early-stage OAK manifested as a subtle osteophyte at TS without narrowing-marginal osteophyte. This undiagnosed-OAK will deteriorate becoming a contributing factor in an increasing incidence of OAK. Methods: This study developed a radiographic OAK-marker based on both osteophyte at TS and compartment narrowing-marginal osteophyte and graded as normal, mild, moderate, and severe. With this marker, both knee radiographs of 1,728 patients with knee pain were analyzed. Results: Among 611 early-stage mild OAK, 562 or 92% started at TS and 49 or 8% at compartment. It suggests the initial development site of OAK, helping develop new site-specific radiographic classification system of OAK accurately to diagnose all severity of OAK at early, intermediate, or late-stage. It showed that Kellgren-Lawrence system missed 92.0% of early-stage mild OAK from diagnosis. Conclusions: A subtle osteophyte at TS is the earliest radiographic sign of OAK. A new radiographic classification system of OAK was suggested for accurate diagnosis of all OAK in severity and at stage. PMID:23675278

  8. Radiographic determinants of implant performance.

    PubMed

    Reddy, M S; Wang, I C

    1999-06-01

    This paper reviews and compares the strengths and weaknesses of radiographic techniques including periapical, occlusal, panoramic, direct digital, motion tomography, and computed tomography. Practical considerations for each method, including availability and accessibility, are discussed. To date, digital subtraction radiography is the most versatile and sensitive method for measuring boss loss. It can detect both bone height and bone mass changes on root-form or blade-form dental implants. Criteria for implant success have changed substantially over the past two decades. In clinical trials of dental implants, the outcomes require certain radiographic analyses to address the hypothesis or clinical question adequately. Radiographic methods best suited to the objective assessment of implant performance and hypothesis were reviewed.

  9. Analog enhancement of radiographic images

    NASA Technical Reports Server (NTRS)

    Baily, N. A.; Nachazel, R. J.

    1976-01-01

    The paper shows how analog methods for edge sharpening, contrast enhancement, and expansion of the range of gray levels of particular interest are effective for easy on-line application to video viewing of X-ray roentgenograms or to fluoroscopy. The technique for analog enhancement of radiographic images is a modified version of the system designed by Fuchs et al. (1972), whereby an all directional second derivative signal called detail signal is used to produce both vertical and horizontal enhancement of the image. Particular attention is given to noise filtration and contrast enhancement. Numerous radiographs supplement the text.

  10. Acid corrosive esophagitis: radiographic findings.

    PubMed

    Muhletaler, C A; Gerlock, A J; de Soto, L; Halter, S A

    1980-06-01

    Thirty-nine esophagograms of 24 patients after ingestion of muriatic acid (27% HCI) in suicide attempts were reviewed. All esophagograms were obtained in the acute, subacute, and chronic phases. In the acute and subacute phases, the radiographic findings consisted of mucosal edema, submucosal edema or hemorrhage, ulcerations, sloughing of the mucosa, atony, and dilatation. Strictures of the esophagus were present in the chronic phase. These radiographic findings were not different from those found in alkaline corrosive esophagitis. The severity of the corrosive esophagitis is considered related to the concentration, amount, viscosity, and duration of contact between the caustic agent and the esophageal mucosa.

  11. Tonsillolith: a panoramic radiograph presentation.

    PubMed

    Babu B, Balaji; Tejasvi M L, Avinash; Avinash, C K Anulekha; B, Chittaranjan

    2013-10-01

    Tonsilloliths are calcifications within a tonsillar crypt, involve primarily the palatine tonsil caused by dystrophic calcification as a result of chronic inflammation. Tonsilloliths are very uncommon and are microscopic. Tonsillar concretions sometimes produce symptoms which include non-specific chronic halitosis, irritable cough, dysphagia, otalgia and foreign body-like sensation or foul taste. Patients with tonsillolithiasis may also be asymptomatic, with their lesions being discovered incidentally on panoramic radiographs. This article presents an unusual case of multiple bilateral and asymptomatic tonsilloliths which were found during a routine panoramic radiographic examination.

  12. Shot H3837: Darht's First Dual-Axis Explosive Experiment

    NASA Astrophysics Data System (ADS)

    Mendez, Jacob; McNeil, Wendy Vogan; Harsh, James; Hull, Lawrence

    2011-06-01

    Test H3837 was the first explosive shot performed in front of both flash x-ray axes at the Los Alamos Dual Axis Radiographic HydroTest (DARHT) facility. Executed in November 2009, the shot was an explosively-driven metal flyer plate in a series of experiments designed to explore equation-of-state properties of shocked materials. Imaging the initial shock wave traveling through the flyer plate, DARHT Axis II captured the range of motion from the shock front emergence in the flyer to breakout at the free surface; the Axis I pulse provided a perpendicular perspective of the shot at a time coinciding with the third pulse of Axis II. Since the days of the Manhattan Project, penetrating radiography with multiple frames from different viewing angles has remained a high-profile goal at the Laboratory. H3837 is merely the beginning of a bright future for two-axis penetrating radiography.

  13. Skew resisting hydrodynamic seal

    DOEpatents

    Conroy, William T.; Dietle, Lannie L.; Gobeli, Jeffrey D.; Kalsi, Manmohan S.

    2001-01-01

    A novel hydrodynamically lubricated compression type rotary seal that is suitable for lubricant retention and environmental exclusion. Particularly, the seal geometry ensures constraint of a hydrodynamic seal in a manner preventing skew-induced wear and provides adequate room within the seal gland to accommodate thermal expansion. The seal accommodates large as-manufactured variations in the coefficient of thermal expansion of the sealing material, provides a relatively stiff integral spring effect to minimize pressure-induced shuttling of the seal within the gland, and also maintains interfacial contact pressure within the dynamic sealing interface in an optimum range for efficient hydrodynamic lubrication and environment exclusion. The seal geometry also provides for complete support about the circumference of the seal to receive environmental pressure, as compared the interrupted character of seal support set forth in U.S. Pat. Nos. 5,873,576 and 6,036,192 and provides a hydrodynamic seal which is suitable for use with non-Newtonian lubricants.

  14. Smoothed Particle Hydrodynamic Simulator

    SciTech Connect

    2016-10-05

    This code is a highly modular framework for developing smoothed particle hydrodynamic (SPH) simulations running on parallel platforms. The compartmentalization of the code allows for rapid development of new SPH applications and modifications of existing algorithms. The compartmentalization also allows changes in one part of the code used by many applications to instantly be made available to all applications.

  15. Hydrodynamics of the Dirac spectrum

    DOE PAGES

    Liu, Yizhuang; Warchoł, Piotr; Zahed, Ismail

    2015-12-15

    We discuss a hydrodynamical description of the eigenvalues of the Dirac spectrum in even dimensions in the vacuum and in the large N (volume) limit. The linearized hydrodynamics supports sound waves. The hydrodynamical relaxation of the eigenvalues is captured by a hydrodynamical (tunneling) minimum configuration which follows from a pertinent form of Euler equation. As a result, the relaxation from a phase of unbroken chiral symmetry to a phase of broken chiral symmetry occurs over a time set by the speed of sound.

  16. Chemical intensification of dental radiographs

    SciTech Connect

    Price, C.

    1983-04-01

    The potential applications of chemical intensification in dental radiography are explored. Three standard photographic intensifiers and three methods designed for radiographic use are evaluated. One of these methods is shown to be capable of reducing radiation dose to one half, without loss of diagnostic quality. Further work is necessary to achieve a system sufficiently practicable to deserve widespread use in routine clinical dental radiography.

  17. Dental radiographic guidelines: a review.

    PubMed

    Kim, Irene H; Mupparapu, Muralidhar

    2009-05-01

    The 2004 American Dental Association (ADA)/US Food and Drug Administration (FDA) radiographic selection criteria and guidelines were reviewed and compared with the prior radiographic selection criteria and guidelines. The authors reviewed the publications from the US FDA, US Department of Health and Human Services, and National Council on Radiation Protection and Measurements. The positions outlined by the Canadian Dental Association and the European Commission were also reviewed and compared to US guidelines. The FDA guidelines were first published in 1987, and several changes have been made to them over the years. Recent literature reveals that the general compliance of these guidelines is very low, especially within dental schools in the United States and Canada. Little is known about the compliance outside of the dental school environment; however, it is expected to be low for various reasons. In 2007, the International Commission on Radiological Protection (ICRP) revised its estimates of tissue radiosensitivity, which resulted in effective doses of dental radiographs 32% to 422% higher than the 1990 ICRP guidelines. Flow charts summarizing the latest guidelines were developed to facilitate general compliance among practitioners. Based on the literature reviewed and the recent ICRP findings, it would be prudent for dental health care professionals to follow dental radiographic guidelines.

  18. Improved radiographic image amplifier panel

    NASA Technical Reports Server (NTRS)

    Brown, R. L., Sr.

    1968-01-01

    Layered image amplifier for radiographic /X ray and gamma ray/ applications, combines very high radiation sensitivity with fast image buildup and erasure capabilities by adding a layer of material that is both photoconductive and light-emitting to basic image amplifier and cascading this assembly with a modified Thorne panel.

  19. Reference for radiographic film interpreters

    NASA Technical Reports Server (NTRS)

    Austin, D. L.

    1970-01-01

    Reference of X-ray film images provides examples of weld defects, film quality, stainless steel welded tubing, and acceptable weld conditions. A summary sheet details the discrepancies shown on the film strip. This reference aids in interpreting and evaluating radiographic film of weldments.

  20. Radiographic findings of Proteus Syndrome.

    PubMed

    Gandhi, Nishant Mukesh; Davalos, Eric A; Varma, Rajeev K

    2014-01-01

    The extremely rare Proteus Syndrome is a hamartomatous congenital syndrome with substantial variability between clinical patient presentations. The diagnostic criteria consist of a multitude of clinical findings including hemihypertrophy, macrodactyly, epidermal nevi, subcutaneous hamartomatous tumors, and bony abnormalities. These clinical findings correlate with striking radiographic findings.

  1. Radiographic findings of Proteus Syndrome

    PubMed Central

    Gandhi, Nishant Mukesh; Davalos, Eric A.; Varma, Rajeev K.

    2015-01-01

    The extremely rare Proteus Syndrome is a hamartomatous congenital syndrome with substantial variability between clinical patient presentations. The diagnostic criteria consist of a multitude of clinical findings including hemihypertrophy, macrodactyly, epidermal nevi, subcutaneous hamartomatous tumors, and bony abnormalities. These clinical findings correlate with striking radiographic findings. PMID:27186241

  2. Postoperative Increased Loading Leads to an Alteration in the Radiological Mechanical Axis After Total Knee Arthroplasty.

    PubMed

    Zahn, Robert Karl; Fussi, Jasmin; von Roth, Philipp; Perka, Carsten F; Hommel, Hagen

    2016-08-01

    Standing long-leg radiographs allow assessment of the mechanical axis in the frontal plane before and after total knee arthroplasty (TKA). An alteration in loading, and hence in the forces acting on the knee joint, occurs postoperatively. We therefore postulated that the mechanical axis measured in the long-leg standing radiograph would change within the first year after TKA. Standing long-leg radiographs of 156 patients were performed 7 days, 3 months, and 12 months after TKA with determination of mechanical axis of the lower limb. Seven days after surgery, the mechanical axis amounted 0.8° ± 1.7° valgus. Three months after the operation, at 1.3° ± 1.3° varus, it was significantly different (P < .001) from the primary measurement. No further alteration in the mechanical axis occurred during the first year after TKA. This difference was even more pronounced (P < .001) in patients with a postoperative lack of complete extension. Seven days after surgery, they had a valgus axis deviation of 1.6° ± 1.6°; after 3 months, the measurement amounted 1.2° ± 1.3° varus. Measured by a standing long-leg radiograph, the frontal mechanical axis after TKA changes over time. The predictive power of a standing long-leg radiograph in the first week after surgery is limited because limb loading is altered because of pain and is therefore nonphysiological. The actual mechanical axis resulting after TKA can only be assessed in a standing long-leg radiograph at physiological loading. Copyright © 2016 Elsevier Inc. All rights reserved.

  3. Hydrodynamics and phases of flocks

    SciTech Connect

    Toner, John; Tu Yuhai . E-mail: yuhai@us.ibm.com; Ramaswamy, Sriram

    2005-07-01

    We review the past decade's theoretical and experimental studies of flocking: the collective, coherent motion of large numbers of self-propelled 'particles' (usually, but not always, living organisms). Like equilibrium condensed matter systems, flocks exhibit distinct 'phases' which can be classified by their symmetries. Indeed, the phases that have been theoretically studied to date each have exactly the same symmetry as some equilibrium phase (e.g., ferromagnets, liquid crystals). This analogy with equilibrium phases of matter continues in that all flocks in the same phase, regardless of their constituents, have the same 'hydrodynamic'-that is, long-length scale and long-time behavior, just as, e.g., all equilibrium fluids are described by the Navier-Stokes equations. Flocks are nonetheless very different from equilibrium systems, due to the intrinsically nonequilibrium self-propulsion of the constituent 'organisms'. This difference between flocks and equilibrium systems is most dramatically manifested in the ability of the simplest phase of a flock, in which all the organisms are, on average moving in the same direction (we call this a 'ferromagnetic' flock; we also use the terms 'vector-ordered' and 'polar-ordered' for this situation) to exist even in two dimensions (i.e., creatures moving on a plane), in defiance of the well-known Mermin-Wagner theorem of equilibrium statistical mechanics, which states that a continuous symmetry (in this case, rotation invariance, or the ability of the flock to fly in any direction) can not be spontaneously broken in a two-dimensional system with only short-ranged interactions. The 'nematic' phase of flocks, in which all the creatures move preferentially, or are simply oriented preferentially, along the same axis, but with equal probability of moving in either direction, also differs dramatically from its equilibrium counterpart (in this case, nematic liquid crystals). Specifically, it shows enormous number fluctuations, which

  4. Vertical Axis Wind Turbine

    SciTech Connect

    Homicz, Greg

    2002-04-01

    Blade fatigue life is an important element in determining the economic viability of the Vertical-Axis Wind Turbine (VAWT). VAWT-SAL Vertical Axis Wind Turbine- Stochastic Aerodynamic Loads Ver 3.2 numerically simulates the stochastic (random0 aerodynamic loads of the Vertical-Axis Wind Turbine (VAWT) created by the atomspheric turbulence. The program takes into account the rotor geometry, operating conditions, and assumed turbulence properties.

  5. Radiographic identification of loose bodies in the traumatized hip joint

    SciTech Connect

    Baird, R.A.; Schobert, W.E.; Pais, M.J.; Ahmed, M.; Wilson, W.J.; Farjalla, G.L.; Imray, T.J.

    1982-12-01

    Acrylic spacers and cubes of cortical bone of known dimensions were placed in predetermined locations in cadaver hip joints, which were then studied with plain radiography and linear, hypocycloidal, and computed tomography (CT). Joint space widening was not measurable on plain radiographs of the pelvis when 2-mm spacers were placed anywhere within the hip joint. When 4-mm spacers were used, widening measured 2 mm in the axis of measurement corresponding to the location of the spacer. Linear tomography did not permit identification of the 2-mm cubes; however, hypocycloidal tomography and CT consistently showed them anywhere within the hip joint. Radiation dose and clinical recommendations are discussed.

  6. Tarsal navicular stress fractures: radiographic evaluation

    SciTech Connect

    Pavlov, H.; Torg, J.S.; Freiberger, R.H.

    1983-09-01

    Tarsal navicular stress fractures are a potential source of disabling foot pain in physically active individuals. The diagnosis of tarsal navicular stress fracture requires a high index of clinical and radiographic suspicion because the fracture is only rarely evident on routine radiographs or standard tomograms. The radiographic diagnosis of a tarsal navicular stress fracture may require anatomic anteroposterior tomograms or a radionuclide bone scan with plantar views. Radiographic examinations of 23 fractures in 21 patients are evaluated.

  7. Hydrodynamics of Turning Flocks.

    PubMed

    Yang, Xingbo; Marchetti, M Cristina

    2015-12-18

    We present a hydrodynamic model of flocking that generalizes the familiar Toner-Tu equations to incorporate turning inertia of well-polarized flocks. The continuum equations controlled by only two dimensionless parameters, orientational inertia and alignment strength, are derived by coarse-graining the inertial spin model recently proposed by Cavagna et al. The interplay between orientational inertia and bend elasticity of the flock yields anisotropic spin waves that mediate the propagation of turning information throughout the flock. The coupling between spin-current density to the local vorticity field through a nonlinear friction gives rise to a hydrodynamic mode with angular-dependent propagation speed at long wavelengths. This mode becomes unstable as a result of the growth of bend and splay deformations augmented by the spin wave, signaling the transition to complex spatiotemporal patterns of continuously turning and swirling flocks.

  8. Nonlinear hydrodynamics. Lecture 9

    SciTech Connect

    Cox, A.N.

    1983-03-14

    A very sophisticated method for calculating the stability and pulsations of stars which make contact with actual observations of the stellar behavior, hydrodynamic calculations are very simple in principle. Conservation of mass can be accounted for by having mass shells that are fixed with their mass for all time. Motions of these shells can be calculated by taking the difference between the external force of gravity and that from the local pressure gradient. The conservation of energy can be coupled to this momentum conservation equation to give the current temperatures, densities, pressures, and opacities at the shell centers, as well as the positions, velocities, and accelerations of the mass shell interfaces. Energy flow across these interfaces can be calculated from the current conditions, and this energy is partitioned between internal energy and the work done on or by the mass shell. We discuss here only the purely radial case for hydrodynamics because it is very useful for stellar pulsation studies.

  9. Superluminous Supernovae hydrodynamic models

    NASA Astrophysics Data System (ADS)

    Orellana, M.

    2017-07-01

    We use our radiation hydrodynamic code in order to simulate magnetar powered Superluminous Supernovae (SLSNe). It is assumed that a central rapidly rotating magnetar deposits all its rotational energy into the ejecta where is added to the usual power. The magnetar luminosity and spin-down timescale are adopted as the free parameters of the model. For the case of ASASSN-15lh, which has been claimed as the most luminous supernova ever discovered, we have found physically plausible magnetar parameters can reproduce the overall shape of the bolometric light curve (LC) provided the progenitor mass is ≍ 8M⊙. The ejecta dynamics of this event shows signs of the magnetar energy input which deviates the expansion from the usually assumed homologous behaviour. Our numerical experiments lead us to conclude that the hydrodynamical modeling is necessary in order to derive the properties of powerful magnetars driving SLSNe.

  10. Hydrodynamics of Turning Flocks

    NASA Astrophysics Data System (ADS)

    Yang, Xingbo; Marchetti, M. Cristina

    2015-12-01

    We present a hydrodynamic model of flocking that generalizes the familiar Toner-Tu equations to incorporate turning inertia of well-polarized flocks. The continuum equations controlled by only two dimensionless parameters, orientational inertia and alignment strength, are derived by coarse-graining the inertial spin model recently proposed by Cavagna et al. The interplay between orientational inertia and bend elasticity of the flock yields anisotropic spin waves that mediate the propagation of turning information throughout the flock. The coupling between spin-current density to the local vorticity field through a nonlinear friction gives rise to a hydrodynamic mode with angular-dependent propagation speed at long wavelengths. This mode becomes unstable as a result of the growth of bend and splay deformations augmented by the spin wave, signaling the transition to complex spatiotemporal patterns of continuously turning and swirling flocks.

  11. Hydrodynamic Design Optimization Tool

    DTIC Science & Technology

    2011-08-01

    appreciated. The authors would also like to thank David Walden and Francis Noblesse of Code 50 for being instrumental in defining this project, Wesley...and efficiently during the early stage of the design process. The Computational Fluid Dynamics ( CFD ) group at George Mason University has an...specific design constraints. In order to apply CFD -based tool to the hydrodynamic design optimization of ship hull forms, an initial hull form is

  12. Radiographic techniques for investigating cereal grains

    SciTech Connect

    Winkler, M.A.

    1981-10-01

    Radiographic examination of cereal grain can determine nondestructively the presence of internal structural damage and other defects, which can be correlated to associated problems such as disease and infestation. Radiographs of several representative grains demonstrate the capabilities of the radiographic technique to detect structural deviations in the grains.

  13. 21 CFR 892.1840 - Radiographic film.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic film. 892.1840 Section 892.1840 Food... DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1840 Radiographic film. (a) Identification. Radiographic film is a device that consists of a thin sheet of radiotransparent material coated on one or...

  14. 21 CFR 892.1840 - Radiographic film.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic film. 892.1840 Section 892.1840 Food... DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1840 Radiographic film. (a) Identification. Radiographic film is a device that consists of a thin sheet of radiotransparent material coated on one or...

  15. 21 CFR 892.1840 - Radiographic film.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic film. 892.1840 Section 892.1840 Food... DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1840 Radiographic film. (a) Identification. Radiographic film is a device that consists of a thin sheet of radiotransparent material coated on one or...

  16. Hydrodynamics of fossil fishes.

    PubMed

    Fletcher, Thomas; Altringham, John; Peakall, Jeffrey; Wignall, Paul; Dorrell, Robert

    2014-08-07

    From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms.

  17. Hydrodynamic blade guide

    DOEpatents

    Blaedel, Kenneth L.; Davis, Pete J.; Landram, Charles S.

    2000-01-01

    A saw having a self-pumped hydrodynamic blade guide or bearing for retaining the saw blade in a centered position in the saw kerf (width of cut made by the saw). The hydrodynamic blade guide or bearing utilizes pockets or grooves incorporated into the sides of the blade. The saw kerf in the workpiece provides the guide or bearing stator surface. Both sides of the blade entrain cutting fluid as the blade enters the kerf in the workpiece, and the trapped fluid provides pressure between the blade and the workpiece as an inverse function of the gap between the blade surface and the workpiece surface. If the blade wanders from the center of the kerf, then one gap will increase and one gap will decrease and the consequent pressure difference between the two sides of the blade will cause the blade to re-center itself in the kerf. Saws using the hydrodynamic blade guide or bearing have particular application in slicing slabs from boules of single crystal materials, for example, as well as for cutting other difficult to saw materials such as ceramics, glass, and brittle composite materials.

  18. Hydrodynamics of insect spermatozoa

    NASA Astrophysics Data System (ADS)

    Pak, On Shun; Lauga, Eric

    2010-11-01

    Microorganism motility plays important roles in many biological processes including reproduction. Many microorganisms propel themselves by propagating traveling waves along their flagella. Depending on the species, propagation of planar waves (e.g. Ceratium) and helical waves (e.g. Trichomonas) were observed in eukaryotic flagellar motion, and hydrodynamic models for both were proposed in the past. However, the motility of insect spermatozoa remains largely unexplored. An interesting morphological feature of such cells, first observed in Tenebrio molitor and Bacillus rossius, is the double helical deformation pattern along the flagella, which is characterized by the presence of two superimposed helical flagellar waves (one with a large amplitude and low frequency, and the other with a small amplitude and high frequency). Here we present the first hydrodynamic investigation of the locomotion of insect spermatozoa. The swimming kinematics, trajectories and hydrodynamic efficiency of the swimmer are computed based on the prescribed double helical deformation pattern. We then compare our theoretical predictions with experimental measurements, and explore the dependence of the swimming performance on the geometric and dynamical parameters.

  19. Hydrodynamics of fossil fishes

    PubMed Central

    Fletcher, Thomas; Altringham, John; Peakall, Jeffrey; Wignall, Paul; Dorrell, Robert

    2014-01-01

    From their earliest origins, fishes have developed a suite of adaptations for locomotion in water, which determine performance and ultimately fitness. Even without data from behaviour, soft tissue and extant relatives, it is possible to infer a wealth of palaeobiological and palaeoecological information. As in extant species, aspects of gross morphology such as streamlining, fin position and tail type are optimized even in the earliest fishes, indicating similar life strategies have been present throughout their evolutionary history. As hydrodynamical studies become more sophisticated, increasingly complex fluid movement can be modelled, including vortex formation and boundary layer control. Drag-reducing riblets ornamenting the scales of fast-moving sharks have been subjected to particularly intense research, but this has not been extended to extinct forms. Riblets are a convergent adaptation seen in many Palaeozoic fishes, and probably served a similar hydrodynamic purpose. Conversely, structures which appear to increase skin friction may act as turbulisors, reducing overall drag while serving a protective function. Here, we examine the diverse adaptions that contribute to drag reduction in modern fishes and review the few attempts to elucidate the hydrodynamics of extinct forms. PMID:24943377

  20. HADES, A Radiographic Simulation Code

    SciTech Connect

    Aufderheide, M.B.; Slone, D.M.; Schach von Wittenau, A.E.

    2000-08-18

    We describe features of the HADES radiographic simulation code. We begin with a discussion of why it is useful to simulate transmission radiography. The capabilities of HADES are described, followed by an application of HADES to a dynamic experiment recently performed at the Los Alamos Neutron Science Center. We describe quantitative comparisons between experimental data and HADES simulations using a copper step wedge. We conclude with a short discussion of future work planned for HADES.

  1. Computer processing of radiographic images

    NASA Technical Reports Server (NTRS)

    Selzer, R. H.

    1984-01-01

    In the past 20 years, a substantial amount of effort has been expended on the development of computer techniques for enhancement of X-ray images and for automated extraction of quantitative diagnostic information. The historical development of these methods is described. Illustrative examples are presented and factors influencing the relative success or failure of various techniques are discussed. Some examples of current research in radiographic image processing is described.

  2. Rib fracture: Different radiographic projections

    PubMed Central

    Assi, Abed-Al Nasser; Nazal, Yasser

    2012-01-01

    Summary Background: Rib fracture is the most common thoracic injury. It is thought to be present in 10% of all traumatic injuries and in almost 40% of patients who sustained severe non-penetrating trauma. There are 12 pairs of ribs. This study reviews various methods of acquisition and reconstruction of radiographic images of traumatic rib fractures in order to determine the optimal views and to simplify rib fracture diagnostics. Material/Methods: Eight different plain radiography pictures of ribs were performed with the patient in an erect position. The following projections were obtained in sequence: oblique at 45° or 30° angle on inspiration, oblique at 45° or 30° angle on expiration as well as 45° and 39° projections during slow and fast breathing. All radiographic examinations were performed using a Philips three-phase scanner installed at the Al- Razi Hospital in Jenin, Palestine. Results: The results demonstrate that the 45° antero-posterior oblique projection performed on expiration is recommended for diagnostics and interpretation of traumatic rib fractures. Conclusions: Conclusion emerging from this study are such that for a 45° oblique view on expiration is recommended for radiographic imaging of patients with clinical signs of fracture, e.g. evaluation of lower rib fractures, while 45° oblique view during fast breathing is recommended for suspected upper rib fractures. PMID:23269931

  3. Non-Radiographic Axial Spondyloarthritis.

    PubMed

    Slobodin, Gleb; Eshed, Iris

    2015-12-01

    The term non-radiographic axial spondyloarthritis (nrAxSpA) was coined for patients who have a clinical picture of ankylosing spondylitis (AS) but do not exhibit radiographic sacroiliitis. The ASAS classification criteria for nrAxSpA, ensuring the recruitment of homogenous study cohorts, were accepted in 2009, although the respective diagnostic criteria for daily clinical practice have not yet been developed. The clinical diagnosis should be based on the composite of clinical symptoms and signs of the disease, HLA B27 status, and magnetic resonance imaging (MRI) of sacroiliac joints. Notably, a negative MRI or HLA B27 does not exclude the diagnosis in patients with a high clinical suspicion for nrAxSpA. The prevalence of nrAxSpA is similar to that of AS, but the former has a higher female preponderance. The rate of progression of nrAxSpA to the radiographic stage of disease (AS) ranges from 10% to 20% over 2 years. Current treatment strategies for nrAxSpA are the same as for AS and include non-steroidal anti-inflammatory drugs and inhibitors of tumor necrosis factor-alpha. While this review summarizes the current achievements in the field of nrAxSpA, further understanding of the epidemiology and natural history of the disease and, particularly, mechanisms of inflammation and subsequent new bone formation is essential for the development of new treatment strategies for nrAxSpA patients.

  4. Hydrodynamic properties of fin whale flippers predict maximum rolling performance.

    PubMed

    Segre, Paolo S; Cade, David E; Fish, Frank E; Potvin, Jean; Allen, Ann N; Calambokidis, John; Friedlaender, Ari S; Goldbogen, Jeremy A

    2016-11-01

    Maneuverability is one of the most important and least understood aspects of animal locomotion. The hydrofoil-like flippers of cetaceans are thought to function as control surfaces that effect maneuvers, but quantitative tests of this hypothesis have been lacking. Here, we constructed a simple hydrodynamic model to predict the longitudinal-axis roll performance of fin whales, and we tested its predictions against kinematic data recorded by on-board movement sensors from 27 free-swimming fin whales. We found that for a given swimming speed and roll excursion, the roll velocity of fin whales calculated from our field data agrees well with that predicted by our hydrodynamic model. Although fluke and body torsion may further influence performance, our results indicate that lift generated by the flippers is sufficient to drive most of the longitudinal-axis rolls used by fin whales for feeding and maneuvering.

  5. Hydrodynamic Elastic Magneto Plastic

    SciTech Connect

    Wilkins, M. L.; Levatin, J. A.

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  6. Hydrodynamics of Ship Propellers

    NASA Astrophysics Data System (ADS)

    Breslin, John P.; Andersen, Poul

    1996-11-01

    This book deals with flows over propellers operating behind ships, and the hydrodynamic forces and movements that the propeller generates on the shaft and on the ship hull. The first part of the book is devoted to fundamentals of the flow about hydrofoil sections and wings, and to propellers in uniform flow, with guidance for design and pragmatic analysis of performance. The second part covers the development of unsteady forces arising from operation in nonuniform hull wakes. A final chapter discusses the optimization of efficiency of compound propulsors. Researchers in ocean technology and naval architecture will find this book appealing.

  7. Incompressible smoothed particle hydrodynamics

    SciTech Connect

    Ellero, Marco Serrano, Mar; Espanol, Pep

    2007-10-01

    We present a smoothed particle hydrodynamic model for incompressible fluids. As opposed to solving a pressure Poisson equation in order to get a divergence-free velocity field, here incompressibility is achieved by requiring as a kinematic constraint that the volume of the fluid particles is constant. We use Lagrangian multipliers to enforce this restriction. These Lagrange multipliers play the role of non-thermodynamic pressures whose actual values are fixed through the kinematic restriction. We use the SHAKE methodology familiar in constrained molecular dynamics as an efficient method for finding the non-thermodynamic pressure satisfying the constraints. The model is tested for several flow configurations.

  8. Hydrodynamic test problems

    SciTech Connect

    Moran, B

    2005-06-02

    We present test problems that can be used to check the hydrodynamic implementation in computer codes designed to model the implosion of a National Ignition Facility (NIF) capsule. The problems are simplified, yet one of them is three-dimensional. It consists of a nearly-spherical incompressible imploding shell subjected to an exponentially decaying pressure on its outer surface. We present a semi-analytic solution for the time-evolution of that shell with arbitrary small three-dimensional perturbations on its inner and outer surfaces. The perturbations on the shell surfaces are intended to model the imperfections that are created during capsule manufacturing.

  9. How to fake hydrodynamic signals

    NASA Astrophysics Data System (ADS)

    Romatschke, Paul

    2016-12-01

    Flow signatures in experimental data from relativistic ion collisions, are usually interpreted as a fingerprint of the presence of a hydrodynamic phase during the evolution of these systems. I review some theoretical ideas to 'fake' this hydrodynamic behavior in p+A and A+A collisions. I find that transverse flow and femtoscopic measurements can easily be forged through non-hydrodynamic evolution, while large elliptic flow requires some non-vanishing interactions in the hot phase.

  10. Hydrodynamic synchronization of flagellar oscillators

    NASA Astrophysics Data System (ADS)

    Friedrich, Benjamin

    2016-11-01

    In this review, we highlight the physics of synchronization in collections of beating cilia and flagella. We survey the nonlinear dynamics of synchronization in collections of noisy oscillators. This framework is applied to flagellar synchronization by hydrodynamic interactions. The time-reversibility of hydrodynamics at low Reynolds numbers requires swimming strokes that break time-reversal symmetry to facilitate hydrodynamic synchronization. We discuss different physical mechanisms for flagellar synchronization, which break this symmetry in different ways.

  11. Molecular Hydrodynamics from Memory Kernels

    NASA Astrophysics Data System (ADS)

    Lesnicki, Dominika; Vuilleumier, Rodolphe; Carof, Antoine; Rotenberg, Benjamin

    2016-04-01

    The memory kernel for a tagged particle in a fluid, computed from molecular dynamics simulations, decays algebraically as t-3 /2 . We show how the hydrodynamic Basset-Boussinesq force naturally emerges from this long-time tail and generalize the concept of hydrodynamic added mass. This mass term is negative in the present case of a molecular solute, which is at odds with incompressible hydrodynamics predictions. Lastly, we discuss the various contributions to the friction, the associated time scales, and the crossover between the molecular and hydrodynamic regimes upon increasing the solute radius.

  12. Single-Axis Accelerometer

    NASA Technical Reports Server (NTRS)

    Tucker, Dennis Stephen (Inventor); Capo-Lugo, Pedro A. (Inventor)

    2016-01-01

    A single-axis accelerometer includes a housing defining a sleeve. An object/mass is disposed in the sleeve for sliding movement therein in a direction aligned with the sleeve's longitudinal axis. A first piezoelectric strip, attached to a first side of the object and to the housing, is longitudinally aligned with the sleeve's longitudinal axis. The first piezoelectric strip includes a first strip of a piezoelectric material with carbon nanotubes substantially aligned along a length thereof. A second piezoelectric strip, attached to a second side of the object and to the housing, is longitudinally aligned with the sleeve's longitudinal axis. The second piezoelectric strip includes a second strip of the piezoelectric material with carbon nanotubes substantially aligned along a length thereof. A voltage sensor is electrically coupled to at least one of the first and second piezoelectric strips.

  13. Mediastinal evaluation utilizing the reverse Trendelenburg radiograph.

    PubMed

    Barker, D E; Crabtree, J D; White, J E; Somberg, L B; Burns, R P

    1999-05-01

    When thoracic aortic rupture is suspected, a 45-degree reverse Trendelenburg (RT) anteroposterior (AP) chest radiograph should place the mediastinal structures in a more appropriate position and allow a more accurate evaluation than a supine AP radiograph. One hundred ninety-one consecutive hemodynamically stable adult patients with major blunt thoracic trauma were initially evaluated for mediastinal abnormalities associated with aortic disruption by both supine AP chest radiograph and an AP chest radiograph with the patient in 45-degree RT position. One hundred four patients underwent contrast aortography based on mediastinal abnormalities detected on the supine AP chest radiograph. Twenty of these patients had abnormal aortograms demonstrating traumatic aortic disruption confirmed at surgery. Supine and RT chest radiographs were retrospectively compared in a blinded fashion to evaluate their specificity and positive predictive value for detection of traumatic thoracic aortic rupture. If RT chest radiographic findings had been used to determine the need for further assessment, 29 angiograms (26%) would have been eliminated, specificity would have increased from 52 per cent to 69 per cent, and positive predictive value would have increased from 19 per cent to 27 per cent. Both supine and RT chest radiographs demonstrated mediastinal widening in all 20 patients with abnormal aortograms, with no missed thoracic aortic disruptions (100% sensitivity). This study indicated that the RT chest radiograph may be used instead of the standard supine radiograph as the initial screen for mediastinal evaluation, maintaining a high sensitivity and eliminating the cost and morbidity of many unnecessary aortograms.

  14. Hydrodynamics of pronuclear migration

    NASA Astrophysics Data System (ADS)

    Nazockdast, Ehssan; Needleman, Daniel; Shelley, Michael

    2014-11-01

    Microtubule (MT) filaments play a key role in many processes involved in cell devision including spindle formation, chromosome segregation, and pronuclear positioning. We present a direct numerical technique to simulate MT dynamics in such processes. Our method includes hydrodynamically mediated interactions between MTs and other cytoskeletal objects, using singularity methods for Stokes flow. Long-ranged many-body hydrodynamic interactions are computed using a highly efficient and scalable fast multipole method, enabling the simulation of thousands of MTs. Our simulation method also takes into account the flexibility of MTs using Euler-Bernoulli beam theory as well as their dynamic instability. Using this technique, we simulate pronuclear migration in single-celled Caenorhabditis elegans embryos. Two different positioning mechanisms, based on the interactions of MTs with the motor proteins and the cell cortex, are explored: cytoplasmic pulling and cortical pushing. We find that although the pronuclear complex migrates towards the center of the cell in both models, the generated cytoplasmic flows are fundamentally different. This suggest that cytoplasmic flow visualization during pronuclear migration can be utilized to differentiate between the two mechanisms.

  15. Hydrodynamics of Bacterial Cooperation

    NASA Astrophysics Data System (ADS)

    Petroff, A.; Libchaber, A.

    2012-12-01

    Over the course of the last several decades, the study of microbial communities has identified countless examples of cooperation between microorganisms. Generally—as in the case of quorum sensing—cooperation is coordinated by a chemical signal that diffuses through the community. Less well understood is a second class of cooperation that is mediated through physical interactions between individuals. To better understand how the bacteria use hydrodynamics to manipulate their environment and coordinate their actions, we study the sulfur-oxidizing bacterium Thiovulum majus. These bacteria live in the diffusive boundary layer just above the muddy bottoms of ponds. As buried organic material decays, sulfide diffuses out of the mud. Oxygen from the pond diffuses into the boundary layer from above. These bacteria form communities—called veils— which are able to transport nutrients through the boundary layer faster than diffusion, thereby increasing their metabolic rate. In these communities, bacteria attach to surfaces and swim in place. As millions of bacteria beat their flagella, the community induces a macroscopic fluid flow, which mix the boundary layer. Here we present experimental observations and mathematical models that elucidate the hydrodynamics linking the behavior of an individual bacterium to the collective dynamics of the community. We begin by characterizing the flow of water around an individual bacterium swimming in place. We then discuss the flow of water and nutrients around a small number of individuals. Finally, we present observations and models detailing the macroscopic dynamics of a Thiovulum veil.

  16. Load responsive hydrodynamic bearing

    DOEpatents

    Kalsi, Manmohan S.; Somogyi, Dezso; Dietle, Lannie L.

    2002-01-01

    A load responsive hydrodynamic bearing is provided in the form of a thrust bearing or journal bearing for supporting, guiding and lubricating a relatively rotatable member to minimize wear thereof responsive to relative rotation under severe load. In the space between spaced relatively rotatable members and in the presence of a liquid or grease lubricant, one or more continuous ring shaped integral generally circular bearing bodies each define at least one dynamic surface and a plurality of support regions. Each of the support regions defines a static surface which is oriented in generally opposed relation with the dynamic surface for contact with one of the relatively rotatable members. A plurality of flexing regions are defined by the generally circular body of the bearing and are integral with and located between adjacent support regions. Each of the flexing regions has a first beam-like element being connected by an integral flexible hinge with one of the support regions and a second beam-like element having an integral flexible hinge connection with an adjacent support region. A least one local weakening geometry of the flexing region is located intermediate the first and second beam-like elements. In response to application of load from one of the relatively rotatable elements to the bearing, the beam-like elements and the local weakening geometry become flexed, causing the dynamic surface to deform and establish a hydrodynamic geometry for wedging lubricant into the dynamic interface.

  17. Pilot-Wave Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Bush, John W. M.

    2015-01-01

    Yves Couder, Emmanuel Fort, and coworkers recently discovered that a millimetric droplet sustained on the surface of a vibrating fluid bath may self-propel through a resonant interaction with its own wave field. This article reviews experimental evidence indicating that the walking droplets exhibit certain features previously thought to be exclusive to the microscopic, quantum realm. It then reviews theoretical descriptions of this hydrodynamic pilot-wave system that yield insight into the origins of its quantum-like behavior. Quantization arises from the dynamic constraint imposed on the droplet by its pilot-wave field, and multimodal statistics appear to be a feature of chaotic pilot-wave dynamics. I attempt to assess the potential and limitations of this hydrodynamic system as a quantum analog. This fluid system is compared to quantum pilot-wave theories, shown to be markedly different from Bohmian mechanics and more closely related to de Broglie's original conception of quantum dynamics, his double-solution theory, and its relatively recent extensions through researchers in stochastic electrodynamics.

  18. Material identification with multichannel radiographs

    NASA Astrophysics Data System (ADS)

    Collins, Noelle; Jimenez, Edward S.; Thompson, Kyle R.

    2017-02-01

    This work aims to validate previous exploratory work done to characterize materials by matching their attenuation profiles using a multichannel radiograph given an initial energy spectrum. The experiment was performed in order to evaluate the effects of noise on the resulting attenuation profiles, which was ignored in simulation. Spectrum measurements have also been collected from various materials of interest. Additionally, a MATLAB optimization algorithm has been applied to these candidate spectrum measurements in order to extract an estimate of the attenuation profile. Being able to characterize materials through this nondestructive method has an extensive range of applications for a wide variety of fields, including quality assessment, industry, and national security.

  19. Signal Acquisition Using AXIe

    NASA Astrophysics Data System (ADS)

    Narciso, Steven J.

    2011-08-01

    An emerging test and measurement standard called AXIe, AdvancedTCA extensions for Instrumentation, is expected to find wide acceptance within the Physics community as it offers many benefits to applications including shock, plasma, particle and nuclear physics. It is expected that many COTS (commercial off-the-shelf) signal conditioning, acquisition and processing modules will become available from a range of different suppliers. AXIe uses AdvancedTCA® as its basis, but then levers test and measurement industry standards such as PXI, IVI, and LXI to facilitate cooperation and plug-and-play interoperability between COTS instrument suppliers. AXIe's large board footprint and power allows high density in a 19" rack, enabling the development of high-performance signal conditioning, analog-to-digital conversion, and data processing, while offering channel count scalability inherent in modular systems. Synchronization between modules is flexible and provided by two triggering structures: a parallel trigger bus, and radially-distributed, time-matched point-to-point trigger lines. Inter-module communication is also provided with an adjacent module local bus allowing data transfer to 600 Gbits/s in each direction, for example between a front-end digitizer and DSP. AXIe allows embedding high performance computing and a range of COTS AdvancedTCA® computer blades are currently available that provide low cost alternatives to the development of custom signal processing modules. The availability of both LAN and PCI Express allow interconnection between modules, as well as industry-standard high-performance data paths to external host computer systems. AXIe delivers a powerful environment for custom module devel opment. As in the case of VXIbus and PXI before it, commercial development kits are expected to be available. This paper will give an overview of the architectural elements of AXIe 1.0, the compatibility model with AdvancedTCA, and signal acquisition performance of many

  20. DIGITAL SPALL RADIOGRAPH ANALYSIS SYSTEM

    SciTech Connect

    CURTIS L. HARRIS - LATA

    1990-01-01

    This report describes progress on work to develop a cost effective, rapid response system for measuring Technology Assessment National Laboratory. momentum and kinetic energy of span for the Advanced Center (ATAC) Armor/Anti-Armor (As) program at Los Alamos The system will exploit data contained in two sets of simultaneous co-planar flash radiographs taken along the center line of anticipated span motion. Data contained in each set (which is proportional to the mass and z-number of the span material intersected by the exposing x-ray at each point) is digitized and used to construct a three dimensional model (called the reconstructed span image) that approximates the original span cloud. From the model the mass of span fragments is computed. The two sets of radiographs, separated in time, represent the span configuration at two instants of time. Span fragments from the first instant are matched with those from the second instant to determine velocity. Evaluation of the fidelity of candidate reconstruction algorithms is the highest priority task in. this development program for the obvious reason that the efficacy of the projected span analysis system depends upon the fidelity of the reconstruction techniques.

  1. Digital processing of radiographic images

    NASA Technical Reports Server (NTRS)

    Bond, A. D.; Ramapriyan, H. K.

    1973-01-01

    Some techniques are presented and the software documentation for the digital enhancement of radiographs. Both image handling and image processing operations are considered. The image handling operations dealt with are: (1) conversion of format of data from packed to unpacked and vice versa; (2) automatic extraction of image data arrays; (3) transposition and 90 deg rotations of large data arrays; (4) translation of data arrays for registration; and (5) reduction of the dimensions of data arrays by integral factors. Both the frequency and the spatial domain approaches are presented for the design and implementation of the image processing operation. It is shown that spatial domain recursive implementation of filters is much faster than nonrecursive implementations using fast fourier transforms (FFT) for the cases of interest in this work. The recursive implementation of a class of matched filters for enhancing image signal to noise ratio is described. Test patterns are used to illustrate the filtering operations. The application of the techniques to radiographic images of metallic structures is demonstrated through several examples.

  2. Observer POD for radiographic testing

    SciTech Connect

    Kanzler, Daniel E-mail: uwe.ewert@bam.de Ewert, Uwe E-mail: uwe.ewert@bam.de Müller, Christina E-mail: uwe.ewert@bam.de; Pitkänen, Jorma

    2015-03-31

    The radiographic testing (RT) is a non-destructive testing (NDT) method capable of finding volumetric and open planar defects depending on their orientation. The radiographic contrast is higher for larger penetrated length of the defect in a component. Even though, the detectability of defects does not only depend on the contrast, but also on the noise, the defect area and the geometry of the defect. The currently applied Probability of Detection (POD) approach uses a detection threshold that is only based on a constant noise level or on a constant contrast threshold. This does not reflect accurately the results of evaluations by human observers. A new approach is introduced, using the widely applied POD evaluation and additionally a detection threshold depending on the lateral area and shape of the indication. This work shows the process of calculating the POD curves with simulated data by the modeling software aRTist and with artificial reference data of different defect types, such as ASTM E 476 EPS plates, flat bottom holes and notches. Additional experiments with different operators confirm that the depth of a defect, the lateral area and shape of its indication contribute with different weight to the detectability of the defect if evaluated by human operators on monitors.

  3. Aspects of causal viscous hydrodynamics

    SciTech Connect

    Bhalerao, R. S.; Gupta, Sourendu

    2008-01-15

    We investigate the phenomenology of freely expanding fluids, with different material properties, evolving through the Israel-Stewart (IS) causal viscous hydrodynamics, and compare our results with those obtained in the relativistic Eckart-Landau-Navier-Stokes (ELNS) acausal viscous hydrodynamics. Through the analysis of scaling invariants we give a definition of thermalization time that can be self-consistently determined in viscous hydrodynamics. Next we construct the solutions for one-dimensional boost-invariant flows. Expansion of viscous fluids is slower than that of one-dimensional ideal fluids, resulting in entropy production. At late times, these flows are reasonably well approximated by solutions obtained in ELNS hydrodynamics. Estimates of initial energy densities from observed final values are strongly dependent on the dynamics one chooses. For the same material, and the same final state, IS hydrodynamics gives the smallest initial energy density. We also study fluctuations about these one-dimensional boost-invariant backgrounds; they are damped in ELNS hydrodynamics but can become sound waves in IS hydrodynamics. The difference is obvious in power spectra due to clear signals of wave-interference in IS hydrodynamics, which is completely absent in ELNS dynamics.

  4. General formulation of transverse hydrodynamics

    SciTech Connect

    Ryblewski, Radoslaw; Florkowski, Wojciech

    2008-06-15

    General formulation of hydrodynamics describing transversally thermalized matter created at the early stages of ultrarelativistic heavy-ion collisions is presented. Similarities and differences with the standard three-dimensionally thermalized relativistic hydrodynamics are discussed. The role of the conservation laws as well as the thermodynamic consistency of two-dimensional thermodynamic variables characterizing transversally thermalized matter is emphasized.

  5. Early radiographic changes in radiation bone injury

    SciTech Connect

    Fujita, M.; Tanimoto, K.; Wada, T.

    1986-06-01

    A chronologic series of periapical radiographs was evaluated for the purpose of detecting damage to bone and tooth-supporting tissues in a patient receiving radiation therapy for a basal cell carcinoma of the mandibular gingiva. Widening of the periodontal space was one of the early radiographic changes observed. It is suggested, from the sequence of radiographic changes, that radiation-induced changed in the circulatory system of the bone might be primarily responsible for the resulting changes.

  6. Hydrodynamics of Peristaltic Propulsion

    NASA Astrophysics Data System (ADS)

    Athanassiadis, Athanasios; Hart, Douglas

    2014-11-01

    A curious class of animals called salps live in marine environments and self-propel by ejecting vortex rings much like jellyfish and squid. However, unlike other jetting creatures that siphon and eject water from one side of their body, salps produce vortex rings by pumping water through siphons on opposite ends of their hollow cylindrical bodies. In the simplest cases, it seems like some species of salp can successfully move by contracting just two siphons connected by an elastic body. When thought of as a chain of timed contractions, salp propulsion is reminiscent of peristaltic pumping applied to marine locomotion. Inspired by salps, we investigate the hydrodynamics of peristaltic propulsion, focusing on the scaling relationships that determine flow rate, thrust production, and energy usage in a model system. We discuss possible actuation methods for a model peristaltic vehicle, considering both the material and geometrical requirements for such a system.

  7. Hydrodynamics, resurgence, and transasymptotics

    NASA Astrophysics Data System (ADS)

    Başar, Gökçe; Dunne, Gerald V.

    2015-12-01

    The second order hydrodynamical description of a homogeneous conformal plasma that undergoes a boost-invariant expansion is given by a single nonlinear ordinary differential equation, whose resurgent asymptotic properties we study, developing further the recent work of Heller and Spalinski [Phys. Rev. Lett. 115, 072501 (2015)]. Resurgence clearly identifies the nonhydrodynamic modes that are exponentially suppressed at late times, analogous to the quasinormal modes in gravitational language, organizing these modes in terms of a trans-series expansion. These modes are analogs of instantons in semiclassical expansions, where the damping rate plays the role of the instanton action. We show that this system displays the generic features of resurgence, with explicit quantitative relations between the fluctuations about different orders of these nonhydrodynamic modes. The imaginary part of the trans-series parameter is identified with the Stokes constant, and the real part with the freedom associated with initial conditions.

  8. Hydrodynamics of Turning Flocks

    NASA Astrophysics Data System (ADS)

    Yang, Xingbo; Marchetti, M. Cristina

    2015-03-01

    We present a hydrodynamic model of flocking that generalizes the familiar Toner-Tu equations to incorporate turning inertia of well polarized flocks. The continuum equations are derived by coarse graining the inertial spin model recently proposed by Cavagna et al. The interplay between orientational inertia and bend elasticity of the flock yields spin waves that mediate the propagation of turning information throughout the flock. When the inertia is large, we find a novel instability that signals the transition to complex spatio-temporal patterns of continuously turning and swirling flocks. This work was supported by the NSF Awards DMR-1305184 and DGE-1068780 at Syracuse University and NSF Award PHY11-25915 and the Gordon and Betty Moore Foundation Grant No. 2919 at the KITP at the University of California, Santa Barbara.

  9. Hydrodynamic simulations of clumps

    NASA Astrophysics Data System (ADS)

    Feldmeier, Achim; Hamann, Wolf-Rainer; Rätzel, D.; Oskinova, Lidia M.

    2008-04-01

    Clumps in hot star winds can originate from shock compression due to the line driven instability. One-dimensional hydrodynamic simulations reveal a radial wind structure consisting of highly compressed shells separated by voids, and colliding with fast clouds. Two-dimensional simulations are still largely missing, despite first attempts. Clumpiness dramatically affects the radiative transfer and thus all wind diagnostics in the UV, optical, and in X-rays. The microturbulence approximation applied hitherto is currently superseded by a more sophisticated radiative transfer in stochastic media. Besides clumps, i.e. jumps in the density stratification, so-called kinks in the velocity law, i.e. jumps in dv/dr, play an eminent role in hot star winds. Kinks are a new type of radiative-acoustic shock, and propagate at super-Abbottic speed.

  10. Hydrodynamics of foams

    NASA Astrophysics Data System (ADS)

    Karakashev, Stoyan I.

    2017-08-01

    This brief review article is devoted to all the aspects related to hydrodynamics of foams. For this reason, we focused at first on the methods for studying the basic structural units of the foams—the foam films (FF) and the Plateau borders (PB), thus reviewing the literature about their drainage. After this, we scrutinized in detail the Derjaguin's works on the electrostatic disjoining pressure along with its Langmuir's interpretation, the microscopic and macroscopic approaches in the theory of the van der Waals disjoining pressure, the DLVO theory, the steric disjoining pressure of de Gennes, and the more recent works on non-DLVO forces. The basic methods for studying of foam drainage are presented as well. Engineering and other applications of foam are reviewed as well. All these aspects are presented from retrospective and perspective viewpoints.

  11. Hydrodynamic effects on coalescence.

    SciTech Connect

    Dimiduk, Thomas G.; Bourdon, Christopher Jay; Grillet, Anne Mary; Baer, Thomas A.; de Boer, Maarten Pieter; Loewenberg, Michael; Gorby, Allen D.; Brooks, Carlton, F.

    2006-10-01

    The goal of this project was to design, build and test novel diagnostics to probe the effect of hydrodynamic forces on coalescence dynamics. Our investigation focused on how a drop coalesces onto a flat surface which is analogous to two drops coalescing, but more amenable to precise experimental measurements. We designed and built a flow cell to create an axisymmetric compression flow which brings a drop onto a flat surface. A computer-controlled system manipulates the flow to steer the drop and maintain a symmetric flow. Particle image velocimetry was performed to confirm that the control system was delivering a well conditioned flow. To examine the dynamics of the coalescence, we implemented an interferometry capability to measure the drainage of the thin film between the drop and the surface during the coalescence process. A semi-automated analysis routine was developed which converts the dynamic interferogram series into drop shape evolution data.

  12. Hydrodynamics of sediment threshold

    NASA Astrophysics Data System (ADS)

    Ali, Sk Zeeshan; Dey, Subhasish

    2016-07-01

    A novel hydrodynamic model for the threshold of cohesionless sediment particle motion under a steady unidirectional streamflow is presented. The hydrodynamic forces (drag and lift) acting on a solitary sediment particle resting over a closely packed bed formed by the identical sediment particles are the primary motivating forces. The drag force comprises of the form drag and form induced drag. The lift force includes the Saffman lift, Magnus lift, centrifugal lift, and turbulent lift. The points of action of the force system are appropriately obtained, for the first time, from the basics of micro-mechanics. The sediment threshold is envisioned as the rolling mode, which is the plausible mode to initiate a particle motion on the bed. The moment balance of the force system on the solitary particle about the pivoting point of rolling yields the governing equation. The conditions of sediment threshold under the hydraulically smooth, transitional, and rough flow regimes are examined. The effects of velocity fluctuations are addressed by applying the statistical theory of turbulence. This study shows that for a hindrance coefficient of 0.3, the threshold curve (threshold Shields parameter versus shear Reynolds number) has an excellent agreement with the experimental data of uniform sediments. However, most of the experimental data are bounded by the upper and lower limiting threshold curves, corresponding to the hindrance coefficients of 0.2 and 0.4, respectively. The threshold curve of this study is compared with those of previous researchers. The present model also agrees satisfactorily with the experimental data of nonuniform sediments.

  13. Radiographical evaluation of ulcerative colitis

    PubMed Central

    Deepak, Parakkal; Bruining, David H.

    2014-01-01

    Radiographical modalities have become important diagnostic tools in cases of ulcerative colitis (UC). Imaging can be used non-invasively to determine the extent of involvement, severity of disease and to detect disease-related complications and extra-intestinal inflammatory bowel disease (IBD) manifestations. While abdominal X-rays and barium enemas still retain their relevance in specific clinical settings, the use of computed tomography enterography (CTE) or magnetic resonance enterography (MRE) are now used as first-line investigations to exclude active small bowel disease in IBD patients and can be utilized to detect active colonic inflammation. Additionally, CT colonography and MR colonography are emerging techniques with potential applications in UC. Ultrasonography, leukocyte scintigraphy and positron emission tomography are novel abdominal imaging modalities currently being explored for IBD interrogations. This plethora of radiological imaging options has become a vital component of UC assessments. PMID:24843072

  14. Nonlinear time series analysis and clustering for jet axis identification in vertical turbulent heated jets.

    PubMed

    Charakopoulos, A K; Karakasidis, T E; Papanicolaou, P N; Liakopoulos, A

    2014-03-01

    In the present work we approach the hydrodynamic problem of discriminating the state of the turbulent fluid region as a function of the distance from the axis of a turbulent jet axis. More specifically, we analyzed temperature fluctuations in vertical turbulent heated jets where temperature time series were recorded along a horizontal line through the jet axis. We employed data from different sets of experiments with various initial conditions out of circular and elliptical shaped nozzles in order to identify time series taken at the jet axis, and discriminate them from those taken near the boundary with ambient fluid using nonconventional hydrodynamics methods. For each temperature time series measured at a different distance from jet axis, we estimated mainly nonlinear measures such as mutual information combined with descriptive statistics measures, as well as some linear and nonlinear dynamic detectors such as Hurst exponent, detrended fluctuation analysis, and Hjorth parameters. The results obtained in all cases have shown that the proposed methodology allows us to distinguish the flow regime around the jet axis and identify the time series corresponding to the jet axis in agreement with the conventional statistical hydrodynamic method. Furthermore, in order to reject the null hypothesis that the time series originate from a stochastic process, we applied the surrogate data method.

  15. Hydrodynamical noise and Gubser flow

    NASA Astrophysics Data System (ADS)

    Yan, Li; Grönqvist, Hanna

    2016-03-01

    Hydrodynamical noise is introduced on top of Gubser's analytical solution to viscous hydrodynamics. With respect to the ultra-central collision events of Pb-Pb, p-Pb and p-p at the LHC energies, we solve the evolution of noisy fluid systems and calculate the radial flow velocity correlations. We show that the absolute amplitude of the hydrodynamical noise is determined by the multiplicity of the collision event. The evolution of azimuthal anisotropies, which is related to the generation of harmonic flow, receives finite enhancements from hydrodynamical noise. Although it is strongest in the p-p systems, the effect of hydrodynamical noise on flow harmonics is found to be negligible, especially in the ultra-central Pb-Pb collisions. For the short-range correlations, hydrodynamical noise contributes to the formation of a near-side peak on top of the correlation structure originated from initial state fluctuations. The shape of the peak is affected by the strength of hydrodynamical noise, whose height and width grow from the Pb-Pb system to the p-Pb and p-p systems.

  16. Vertical axis windmill

    SciTech Connect

    Campbell, J.S.

    1980-04-08

    A vertical axis windmill is described which involves a rotatable central vertical shaft having horizontal arms pivotally supporting three sails that are free to function in the wind like the main sail on a sail boat, and means for disabling the sails to allow the windmill to be stopped in a blowing wind.

  17. Doping explosive materials for neutron radiographic enhancement.

    NASA Technical Reports Server (NTRS)

    Golliher, K. G.

    1971-01-01

    Discussion of studies relating to the selection of doping materials of high neutron absorption usable for enhancing the neutron radiographic imaging of explosive mixtures, without interfering with the proper chemical reaction of the explosives. The results of the studies show that gadolinium oxide is an excellent material for doping explosive mixtures to enhance the neutron radiographic image.

  18. Abdominal Plain Radiograph in Neonatal Intestinal Obstruction

    PubMed Central

    Prasad, G Raghavendra; Aziz, Amtul

    2017-01-01

    A comprehensive all-inclusive resource on plain radiograph in neonatal intestinal obstruction is presented. This is an attempt to develop a protocol and to regain expertise in evaluating a plain radiograph that most often yields more than enough clues to diagnose and to decide a plan of action. PMID:28083492

  19. Radiographic simulations and analysis for ASCI

    SciTech Connect

    Aufderheide, M.; Stone, D.; VonWittenau, A.

    1998-12-18

    In this paper, the authors describe their work on developing quantitatively accurate radiographic simulation and analysis tools for ASCI hydro codes. they have extended the ability of HADES, the code which simulates radiography through a mesh, to treat the complex meshes used in ASCI calculations. The ultimate goal is to allow direct comparison between experimental radiographs and full physics simulated radiographs of ASCI calculations. They describe the ray-tracing algorithm they have developed for fast, accurate simulation of dynamic radiographs with the meshes used in ALE3D, an LLNL ASCI code. Spectral effects and material compositions are included. In addition to the newness of the mesh types, the distributed nature of domain decomposed problems requires special treatment by the radiographic code. Because of the size of such problems, they have parallelized the radiographic simulation, in order to have quick turnaround time. presently, this is done using the domain decomposition from the hydro code. They demonstrate good parallel scaling as the size of the problem is increased. They show a comparison between an experimental radiograph of a high explosive detonation and a simulated radiograph of an ALE3D calculation. They conclude with a discussion of future work.

  20. Doping explosive materials for neutron radiographic enhancement.

    NASA Technical Reports Server (NTRS)

    Golliher, K. G.

    1971-01-01

    Discussion of studies relating to the selection of doping materials of high neutron absorption usable for enhancing the neutron radiographic imaging of explosive mixtures, without interfering with the proper chemical reaction of the explosives. The results of the studies show that gadolinium oxide is an excellent material for doping explosive mixtures to enhance the neutron radiographic image.

  1. 21 CFR 892.1910 - Radiographic grid.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic grid. 892.1910 Section 892.1910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1910 Radiographic grid. (a) Identification....

  2. 21 CFR 892.1910 - Radiographic grid.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic grid. 892.1910 Section 892.1910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1910 Radiographic grid. (a) Identification....

  3. 21 CFR 892.1910 - Radiographic grid.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic grid. 892.1910 Section 892.1910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1910 Radiographic grid. (a) Identification....

  4. 21 CFR 892.1910 - Radiographic grid.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic grid. 892.1910 Section 892.1910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1910 Radiographic grid. (a) Identification....

  5. 21 CFR 892.1910 - Radiographic grid.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic grid. 892.1910 Section 892.1910 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1910 Radiographic grid. (a) Identification....

  6. 21 CFR 892.1840 - Radiographic film.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic film. 892.1840 Section 892.1840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1840 Radiographic film. (a) Identification...

  7. 21 CFR 892.1840 - Radiographic film.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic film. 892.1840 Section 892.1840 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1840 Radiographic film. (a) Identification...

  8. Constraining relativistic viscous hydrodynamical evolution

    SciTech Connect

    Martinez, Mauricio; Strickland, Michael

    2009-04-15

    We show that by requiring positivity of the longitudinal pressure it is possible to constrain the initial conditions one can use in second-order viscous hydrodynamical simulations of ultrarelativistic heavy-ion collisions. We demonstrate this explicitly for (0+1)-dimensional viscous hydrodynamics and discuss how the constraint extends to higher dimensions. Additionally, we present an analytic approximation to the solution of (0+1)-dimensional second-order viscous hydrodynamical evolution equations appropriate to describe the evolution of matter in an ultrarelativistic heavy-ion collision.

  9. Special Relativistic Hydrodynamics with Gravitation

    NASA Astrophysics Data System (ADS)

    Hwang, Jai-chan; Noh, Hyerim

    2016-12-01

    Special relativistic hydrodynamics with weak gravity has hitherto been unknown in the literature. Whether such an asymmetric combination is possible has been unclear. Here, the hydrodynamic equations with Poisson-type gravity, considering fully relativistic velocity and pressure under the weak gravity and the action-at-a-distance limit, are consistently derived from Einstein’s theory of general relativity. An analysis is made in the maximal slicing, where the Poisson’s equation becomes much simpler than our previous study in the zero-shear gauge. Also presented is the hydrodynamic equations in the first post-Newtonian approximation, now under the general hypersurface condition. Our formulation includes the anisotropic stress.

  10. Surgical treatment of complex axis fractures with adjacent segment instability.

    PubMed

    Wang, Lei; Xia, Tian; Dong, Shuanghai; Zhao, Qinghua; Tian, Jiwei

    2012-03-01

    This study investigates the clinical and radiographic characteristics of complex axis fractures with adjacent segment instability and describes the outcome of surgical treatment. Twenty-one patients (14 male, seven female; mean age=34 years) with complex axis fractures and adjacent segment instability who were treated between August 2003 and June 2009 were retrospectively reviewed. Treatment selection was based on fracture type and stability of the upper cervical segments. All patients were immobilized with a hard collar for three months after surgery. The mean follow-up period was 12 months (range=6-36 months). No intraoperative surgery-related complications were observed and fusion was achieved in all patients. The outcome was excellent for 17 patients, good for two patients, fair for one patient, and poor for one patient. The upper cervical segments that can become unstable due to complex axis fractures include the atlantoaxial and C2-3 joints. Recommended surgical treatments produce good results.

  11. Hydrodynamics of micropipette aspiration.

    PubMed Central

    Drury, J L; Dembo, M

    1999-01-01

    The dynamics of human neutrophils during micropipette aspiration are frequently analyzed by approximating these cells as simple slippery droplets of viscous fluid. Here, we present computations that reveal the detailed predictions of the simplest and most idealized case of such a scheme; namely, the case where the fluid of the droplet is homogeneous and Newtonian, and the surface tension of the droplet is constant. We have investigated the behavior of this model as a function of surface tension, droplet radius, viscosity, aspiration pressure, and pipette radius. In addition, we have tabulated a dimensionless factor, M, which can be utilized to calculate the apparent viscosity of the slippery droplet. Computations were carried out using a low Reynolds number hydrodynamics transport code based on the finite-element method. Although idealized and simplistic, we find that the slippery droplet model predicts many observed features of neutrophil aspiration. However, there are certain features that are not observed in neutrophils. In particular, the model predicts dilation of the membrane past the point of being continuous, as well as a reentrant jet at high aspiration pressures. PMID:9876128

  12. Astrophysical smooth particle hydrodynamics

    NASA Astrophysics Data System (ADS)

    Rosswog, Stephan

    2009-04-01

    The paper presents a detailed review of the smooth particle hydrodynamics (SPH) method with particular focus on its astrophysical applications. We start by introducing the basic ideas and concepts and thereby outline all ingredients that are necessary for a practical implementation of the method in a working SPH code. Much of SPH's success relies on its excellent conservation properties and therefore the numerical conservation of physical invariants receives much attention throughout this review. The self-consistent derivation of the SPH equations from the Lagrangian of an ideal fluid is the common theme of the remainder of the text. We derive a modern, Newtonian SPH formulation from the Lagrangian of an ideal fluid. It accounts for changes of the local resolution lengths which result in corrective, so-called "grad-h-terms". We extend this strategy to special relativity for which we derive the corresponding grad-h equation set. The variational approach is further applied to a general-relativistic fluid evolving in a fixed, curved background space-time. Particular care is taken to explicitly derive all relevant equations in a coherent way.

  13. Engineering Hydrodynamic AUV Hulls

    NASA Astrophysics Data System (ADS)

    Allen, J.

    2016-12-01

    AUV stands for autonomous underwater vehicle. AUVs are used in oceanography and are similar to gliders. MBARIs AUVs as well as other AUVs map the ocean floor which is very important. They also measure physical characteristics of the water, such as temperature and salinity. My science fair project for 4th grade was a STEM activity in which I built and tested 3 different AUV bodies. I wanted to find out which design was the most hydrodynamic. I tested three different lengths of AUV hulls to see which AUV would glide the farthest. The first was 6 inches. The second was 12 inches and the third was 18 inches. I used clay for the nosecone and cut a ruler into two and made it the fin. Each AUV used the same nosecone and fin. I tested all three designs in a pool. I used biomimicry to create my hypothesis. When I was researching I found that long slim animals swim fastest. So, my hypothesis is the longer AUV will glide farthest. In the end I was right. The longer AUV did glide the farthest.

  14. Spin hydrodynamic generation

    NASA Astrophysics Data System (ADS)

    Takahashi, R.; Matsuo, M.; Ono, M.; Harii, K.; Chudo, H.; Okayasu, S.; Ieda, J.; Takahashi, S.; Maekawa, S.; Saitoh, E.

    2016-01-01

    Magnetohydrodynamic generation is the conversion of fluid kinetic energy into electricity. Such conversion, which has been applied to various types of electric power generation, is driven by the Lorentz force acting on charged particles and thus a magnetic field is necessary. On the other hand, recent studies of spintronics have revealed the similarity between the function of a magnetic field and that of spin-orbit interactions in condensed matter. This suggests the existence of an undiscovered route to realize the conversion of fluid dynamics into electricity without using magnetic fields. Here we show electric voltage generation from fluid dynamics free from magnetic fields; we excited liquid-metal flows in a narrow channel and observed longitudinal voltage generation in the liquid. This voltage has nothing to do with electrification or thermoelectric effects, but turned out to follow a universal scaling rule based on a spin-mediated scenario. The result shows that the observed voltage is caused by spin-current generation from a fluid motion: spin hydrodynamic generation. The observed phenomenon allows us to make mechanical spin-current and electric generators, opening a door to fluid spintronics.

  15. Lotic Water Hydrodynamic Model

    SciTech Connect

    Judi, David Ryan; Tasseff, Byron Alexander

    2015-01-23

    Water-related natural disasters, for example, floods and droughts, are among the most frequent and costly natural hazards, both socially and economically. Many of these floods are a result of excess rainfall collecting in streams and rivers, and subsequently overtopping banks and flowing overland into urban environments. Floods can cause physical damage to critical infrastructure and present health risks through the spread of waterborne diseases. Los Alamos National Laboratory (LANL) has developed Lotic, a state-of-the-art surface water hydrodynamic model, to simulate propagation of flood waves originating from a variety of events. Lotic is a two-dimensional (2D) flood model that has been used primarily for simulations in which overland water flows are characterized by movement in two dimensions, such as flood waves expected from rainfall-runoff events, storm surge, and tsunamis. In 2013, LANL developers enhanced Lotic through several development efforts. These developments included enhancements to the 2D simulation engine, including numerical formulation, computational efficiency developments, and visualization. Stakeholders can use simulation results to estimate infrastructure damage and cascading consequences within other sets of infrastructure, as well as to inform the development of flood mitigation strategies.

  16. Reciprocal relations in dissipationless hydrodynamics

    SciTech Connect

    Melnikovsky, L. A.

    2014-12-15

    Hidden symmetry in dissipationless terms of arbitrary hydrodynamics equations is recognized. We demonstrate that all fluxes are generated by a single function and derive conventional Euler equations using the proposed formalism.

  17. Digital radiographic localization for CT scanning of the larynx

    SciTech Connect

    Silverman, P.M.; Korobkin, M.; Rauch, R.F.

    1983-12-01

    Computed tomography (CT) of the larynx is the preferred method for staging laryngeal carcinoma and assessing the extent of injury from trauma. The standard method of examination consists of 5 mm contiguous scans throughout the larynx in quiet respiration. Scans are performed with the patient supine with the neck slightly extended allowing the long axis of the larynx to be perpendicular to the scanning plane. A complete examination requires scanning from the supraglottic region (level of hyoid bone) to the subglottic region (level of cricoid cartlage). In the authors' experience when this method is used, multiple scans are performed cephalad to the level of interest because no upper limit of the examination is established before transaxial scans are done. We have used the lateral digital radiograph of the neck to identify specific landmarks so that the upper and lower limets of the examination can be established before scanning.

  18. Multiple axis reticle

    NASA Technical Reports Server (NTRS)

    Barns, Chris E. (Inventor); Gunter, William D. (Inventor)

    1990-01-01

    A reticle permits the alignment of three orthogonal axes (X, Y and Z) that intersect at a common target point. Thin, straight filaments are supported on a frame. The filaments are each contained in a different orthogonal plane (S sub xy, S sub xz, and S sub yz) and each filament intersects two of the three orthogonal axes. The filaments, as viewed along the frame axis, give the appearance of a triangle with a V extending from each triangle vertex. When axial alignment is achieved, the filament portions adjacent to a triangle vertex are seen (along the axis of interest) as a right-angle cross, whereas these filament portions are seen to intersect at an oblique angle when axial misalignment occurs. The reticle is open in the region near the target point leaving ample space for alignment aids such as a pentaprism or a cube mirror.

  19. Radiographic examination of mesiodens and their associated complications.

    PubMed

    Asaumi, J I; Shibata, Y; Yanagi, Y; Hisatomi, M; Matsuzaki, H; Konouchi, H; Kishi, K

    2004-03-01

    To examine mesiodens with regard to their status, their influence on adjacent teeth and their alteration during the follow-up period. From retrospective reviews of all patients who visited our institution from 1990-2001, we identified 200 patients (256 mesiodentes) who were shown to have mesiodentes on the basis of a periapical radiograph, a panoramic radiograph or an axial radiograph. The number of supernumerary teeth was one in 146 cases (73%), two in 52 cases (26%) and three in 2 cases (1%). Of 256 mesiodentes, the direction of the crown of the mesiodens was inverted in 172 (67%), in a normal direction in 69 (27%) and in a horizontal direction with regard to the tooth axis in 15 (6%). Of the 147 mesiodentes for which axial radiography was performed, 131 (89%) were located at a palatal site against the dental arch, 16 (11%) overlapped the dental arch and none were at a labial site. Of our 200 cases, a delay of eruption of the permanent central incisor was seen in 12 (6%), malposition or rotation of the central incisor in 5 (2.5%) and dentigerous cyst formation arising from mesiodens in 22 (11%). Marked movement of the mesiodens was seen in 10 cases during the follow-up period of 5-7 years. Some complication arising from mesiodens was seen in 19.5% of all cases in our research. Although mesiodentes are not caused by malocclusion, they may cause it. A long period of impaction of mesiodentes may bring about dentigerous cyst formation or movement of the mesiodentes.

  20. Slurry bubble column hydrodynamics

    NASA Astrophysics Data System (ADS)

    Rados, Novica

    Slurry bubble column reactors are presently used for a wide range of reactions in both chemical and biochemical industry. The successful design and scale up of slurry bubble column reactors require a complete understanding of multiphase fluid dynamics, i.e. phase mixing, heat and mass transport characteristics. The primary objective of this thesis is to improve presently limited understanding of the gas-liquid-solid slurry bubble column hydrodynamics. The effect of superficial gas velocity (8 to 45 cm/s), pressure (0.1 to 1.0 MPa) and solids loading (20 and 35 wt.%) on the time-averaged solids velocity and turbulent parameter profiles has been studied using Computer Automated Radioactive Particle Tracking (CARPT). To accomplish this, CARPT technique has been significantly improved for the measurements in highly attenuating systems, such as high pressure, high solids loading stainless steel slurry bubble column. At a similar set of operational conditions time-averaged gas and solids holdup profiles have been evaluated using the developed Computed Tomography (CT)/Overall gas holdup procedure. This procedure is based on the combination of the CT scans and the overall gas holdup measurements. The procedure assumes constant solids loading in the radial direction and axially invariant cross-sectionally averaged gas holdup. The obtained experimental holdup, velocity and turbulent parameters data are correlated and compared with the existing low superficial gas velocities and atmospheric pressure CARPT/CT gas-liquid and gas-liquid-solid slurry data. The obtained solids axial velocity radial profiles are compared with the predictions of the one dimensional (1-D) liquid/slurry recirculation phenomenological model. The obtained solids loading axial profiles are compared with the predictions of the Sedimentation and Dispersion Model (SDM). The overall gas holdup values, gas holdup radial profiles, solids loading axial profiles, solids axial velocity radial profiles and solids

  1. Unusual radiographic appearance of adamantinoma.

    PubMed

    Cappuccio, Michele; Montalti, Maurizio; Bosco, Giuseppe; Gasbarrini, Alessandro; Boriani, Stefano

    2009-12-01

    Adamantinoma is a rare tumor with an indolent course that occurs most commonly in the tibia. It is locally aggressive, and local recurrences are described after resection. Pain is the most common symptom. Since the lesion is typically slow growing, the pain can be present for many years before the patient seeks medical attention. Microscopically, adamantinoma consists of islands of epithelial cells in a fibrous stroma. Nuclear atypia is minimal, and mitotic figures are rare. The most common radiographic appearance is that of multiple sharply demarcated radiolucent lesions surrounded by areas of dense, sclerotic bone. This tumor most often affects the tibial diaphysis and produces lytic lesions that can cause fractures. A 31-year-old man presented with a rapidly growing lytic lesion of the distal tibia. On histological examination, many areas of epithelial cells in a fibrous stroma were identified. Diagnosis of adamantinoma was performed. The lesion was treated with en bloc resection and reconstruction with distal tibia allograft and ankle arthrodesis with retrograde nail. At 2-year follow-up, there were no clinical or radiological signs of recurrence of disease.

  2. A comparison of scanned lateral cephalograms with corresponding original radiographs.

    PubMed

    Bruntz, Lance Q; Palomo, J Martin; Baden, Sally; Hans, Mark G

    2006-09-01

    Digital cephalometric radiography is gaining popularity in orthodontic practices. However, few studies have compared measurements and superimpositions on analog radiographs with those made on scanned digital images. The objectives of this study were to evaluate distortion associated with scanning lateral cephalograms and printing to hard copy, and to assess the accuracy of digital images for regular cephalometric tasks. Pretreatment and posttreatment cephalograms from 30 subjects were selected and 3 groups were created: original, digital, and hard copy. All films had 8 fiducial marks punched and were scanned at 150 dots per inch. The hard copies were created with a laser printer. Twenty-three cephalometric measures and 3 superimpositions were evaluated for distortion, measurement accuracy, and superimposition results. Paired t tests were used to assess statistical significance. Distortion between the original and the scanned image showed 0.8 mm vertical enlargement and 0.4 mm horizontal reduction. Printed radiographs had 1.1 mm vertical and 0.4 mm horizontal enlargement. All differences were statistically significant. Cephalometric comparisons between original and digital images showed statistical differences in Frankfort horizontal (FH)-occlusal plane, maxillary central incisor-FH, facial plane, y-axis, Frankfort plane to mandibular plane angle (FMA), and FH-Naison to point A (NA). Significant differences also were found in facial plane, y-axis, FMA, and FH-NA when comparing the digital and the hard-copy images. All measurements with differences contained the landmarks porion and orbitale. No differences were found between the original and the hard-copy images. Likewise, no significant differences were found between the original and the digital superimpositions. Although some distortion was found, the relatively small horizontal and vertical discrepancies were deemed clinically insignificant. Landmark identification errors on scanned images contributed to the

  3. Angular-compliant hydrodynamic bearing performance under dynamic loads

    NASA Astrophysics Data System (ADS)

    Harnoy, A.; Rachoor, H.

    1993-07-01

    The study is focused on a dynamically loaded composite bearing, consisting of a hydrodynamic journal bearing inside the internal race of a rolling-element bearing. In this combination, the hydrodynamic bearing has an angular-compliant sleeve with a restricted freedom of rotation around its axis. Under static loads, the improvement is primarily in a significant reduction of friction and wear during the starting and stopping. Under periodical loads, our analysis shows that the performance depends on two dimensionless design parameters. Below particular critical values of these parameters, the results show a considerable improvement, demonstrated by a reduction of the maximum eccentricity. However, above the critical values, the bearing becomes unstable. These results indicate the significance of incorporating this computer assisted computation for each design.

  4. Radiographic findings in congenital lead poisoning

    SciTech Connect

    Pearl, M.; Boxt, L.M.

    1980-07-01

    Because lead crosses the placenta throughout pregnancy, the fetus is at risk for lead poisoning. A full term, asymptomatic child was born with congenital lead poisoning secondary to maternal pica. Radiographic findings of a dense cranial vault, lead lines, and delayed skeletal and deciduous dental development were noted at birth. After chelation therapy, when the patient was seven months old, radiographs revealed normal skeletal maturation. Tooth eruption did not occur until 15 months of age. Newborn infants with these radiographic findings should be screened for subclinical, congenital lead poisoning.

  5. Radiographic anatomical relationship between spinous process and pedicle in thoracolumbar and lumbar spine.

    PubMed

    Cui, Xingang; Wang, Guodong

    2017-05-01

    Pedicle screws are widely used in spinal surgeries, but it remains technically demanding to place. There are numerous studies on the anatomy of pedicle; however, there is very little insight on the relationship between the pedicle and the spinous process, which is an important part of the spinal posterior column.The aim of the study was to investigate the radiographic anatomical relationship between spinous processes and pedicles in the thoracolumbar and lumbar spine, in order to reveal a novel entrance point for pedicle screw insertion.Sixty candidates were enrolled in this study; cases were excluded with degenerative disorders and other disorders as osteoporosis, deformity, and tumor. Radiographs and computer tomography scans between T10 and L5 were obtained on each case. The distance was measured that between the superior margin of spinous process root and the superior border, the inferior border and the axis of pedicle. In laboratory, 5 fresh cadavers were used to imitate the pedicle screw insertion.The basic reference point was supposed as the intersection between the horizontal line of superior margin of spinous process root and the central vertical line of the superior facet. For T10 to T12, the pedicle axis was 5 mm beyond the reference point. For L1 to L4, the pedicle axis was at the reference point. At L5, the pedicle axis was 5 mm beneath the reference point. In laboratory, 80 screws were all inserted into pedicles successfully according to the newly referred entrance point.The study reveals the radiographic anatomical relationship between the pedicle and the spinous process. The pedicle axis is around the horizontal line of the superior margin of spinous process root. It provides a new anatomic mark of pedicle screw entrance point.

  6. Radiographic anatomical relationship between spinous process and pedicle in thoracolumbar and lumbar spine

    PubMed Central

    Cui, Xingang; Wang, Guodong

    2017-01-01

    Abstract Pedicle screws are widely used in spinal surgeries, but it remains technically demanding to place. There are numerous studies on the anatomy of pedicle; however, there is very little insight on the relationship between the pedicle and the spinous process, which is an important part of the spinal posterior column. The aim of the study was to investigate the radiographic anatomical relationship between spinous processes and pedicles in the thoracolumbar and lumbar spine, in order to reveal a novel entrance point for pedicle screw insertion. Sixty candidates were enrolled in this study; cases were excluded with degenerative disorders and other disorders as osteoporosis, deformity, and tumor. Radiographs and computer tomography scans between T10 and L5 were obtained on each case. The distance was measured that between the superior margin of spinous process root and the superior border, the inferior border and the axis of pedicle. In laboratory, 5 fresh cadavers were used to imitate the pedicle screw insertion. The basic reference point was supposed as the intersection between the horizontal line of superior margin of spinous process root and the central vertical line of the superior facet. For T10 to T12, the pedicle axis was 5 mm beyond the reference point. For L1 to L4, the pedicle axis was at the reference point. At L5, the pedicle axis was 5 mm beneath the reference point. In laboratory, 80 screws were all inserted into pedicles successfully according to the newly referred entrance point. The study reveals the radiographic anatomical relationship between the pedicle and the spinous process. The pedicle axis is around the horizontal line of the superior margin of spinous process root. It provides a new anatomic mark of pedicle screw entrance point. PMID:28538370

  7. The hydrodynamics of colloidal gelation.

    PubMed

    Varga, Zsigmond; Wang, Gang; Swan, James

    2015-12-14

    Colloidal gels are formed during arrested phase separation. Sub-micron, mutually attractive particles aggregate to form a system spanning network with high interfacial area, far from equilibrium. Models for microstructural evolution during colloidal gelation have often struggled to match experimental results with long standing questions regarding the role of hydrodynamic interactions. In nearly all models, these interactions are neglected entirely. In the present work, we report simulations of gelation with and without hydrodynamic interactions between the suspended particles executed in HOOMD-blue. The disparities between these simulations are striking and mirror the experimental-theoretical mismatch in the literature. The hydrodynamic simulations agree with experimental observations, however. We explore a simple model of the competing transport processes in gelation that anticipates these disparities, and conclude that hydrodynamic forces are essential. Near the gel boundary, there exists a competition between compaction of individual aggregates which suppresses gelation and coagulation of aggregates which enhances it. The time scale for compaction is mildly slowed by hydrodynamic interactions, while the time scale for coagulation is greatly accelerated. This enhancement to coagulation leads to a shift in the gel boundary to lower strengths of attraction and lower particle concentrations when compared to models that neglect hydrodynamic interactions. Away from the gel boundary, differences in the nearest neighbor distribution and fractal dimension persist within gels produced by both simulation methods. This result necessitates a fundamental rethinking of how dynamic, discrete element models for gelation kinetics are developed as well as how collective hydrodynamic interactions influence the arrest of attractive colloidal dispersions.

  8. Purely hydrodynamic ordering of rotating disks at a finite Reynolds number

    NASA Astrophysics Data System (ADS)

    Goto, Yusuke; Tanaka, Hajime

    2015-01-01

    Self-organization of moving objects in hydrodynamic environments has recently attracted considerable attention in connection to natural phenomena and living systems. However, the underlying physical mechanism is much less clear due to the intrinsically nonequilibrium nature, compared with self-organization of thermal systems. Hydrodynamic interactions are believed to play a crucial role in such phenomena. To elucidate the fundamental physical nature of many-body hydrodynamic interactions at a finite Reynolds number, here we study a system of co-rotating hard disks in a two-dimensional viscous fluid at zero temperature. Despite the absence of thermal noise, this system exhibits rich phase behaviours, including a fluid state with diffusive dynamics, a cluster state, a hexatic state, a glassy state, a plastic crystal state and phase demixing. We reveal that these behaviours are induced by the off-axis and many-body nature of nonlinear hydrodynamic interactions and the finite time required for propagating the interactions by momentum diffusion.

  9. Film adhesive enhances neutron radiographic images

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1978-01-01

    Resolution of neutron radiographic images of thermally conductive film is increased by replacing approximately 5 percent of aluminum powder, which provides thermal conductivity, with gadolinium oxide. Oxide is also chemically stable.

  10. The forensic importance of frontal sinus radiographs.

    PubMed

    da Silva, Rhonan Ferreira; Prado, Felippe Bevilacqua; Caputo, Isamara Geandra Cavalcanti; Devito, Karina Lopes; Botelho, Tessa de Luscena; Daruge Júnior, Eduardo

    2009-01-01

    The identification of unidentified human remains through the comparison of antemortem and postmortem radiographs has found wide acceptance in recent years. Reported here is the forensic case of an unidentified adult male who had died as the result of a traffic accident, after which the body was identified by matching images of ante- and postmortem radiographs of the frontal sinus. A general discussion on identification using frontal sinus radiographs is presented, highlighting the reliability of this method, in reference to the uniqueness of the frontal sinus in humans. However, it also notes a few difficulties, especially in reference to the X-ray technique in cases where antemortem radiographs are available and a potentially larger number of anatomical, pathological or traumatic features are present. The comparison of frontal sinus outlines is recommended when it may become necessary to provide quantitative substantiation for forensic identification based on these structures.

  11. Gastroduodenal lesions of ingested acids: radiographic findings.

    PubMed

    Muhletaler, C A; Gerlock, A J; de Soto, L; Halter, S A

    1980-12-01

    Abdominal radiographs and barium studies of the stomach and duodenum of 27 patients after ingestion of muriatic acid (27% HCl) in suicidal attempts were reviewed. Eleven patients were studied in the acute phase (1-10 days), nine in the subacute phase (11-20 days), and 15 in the chronic phase (21 days or more). Extensive gastric and duodenal mucosal and submucosal damage was radiographically demonstrated in all patients studied in the acute and subacute phase. Four patients had gastric perforation. The radiographic findings in the chronic phase were characterized by marked contraction of the lesser curvature, antral stenosis, irregular gastric contours, and deformed duodenal bulb. Esophageal mucosal and submucosal lesions were radiographically demonstrated in all these patients.

  12. Film adhesive enhances neutron radiographic images

    NASA Technical Reports Server (NTRS)

    Reed, M. W.

    1978-01-01

    Resolution of neutron radiographic images of thermally conductive film is increased by replacing approximately 5 percent of aluminum powder, which provides thermal conductivity, with gadolinium oxide. Oxide is also chemically stable.

  13. Method prevents secondary radiation in radiographic inspection

    NASA Technical Reports Server (NTRS)

    Struckus, A. A.

    1967-01-01

    Thin-walled neoprene containers prevent secondary radiation, scatter, and undercut during radiographic inspection. The containers are filled with a mixture of barium sulfate, red lead, and petroleum jelly that achieves the required absorption rate.

  14. Radiographic selection criteria: new guidelines, old challenges.

    PubMed

    Horner, K

    2013-02-01

    Radiographic selection criteria are a legal requirement for any establishment using ionising radiation for medical purposes, including dental practices. The Faculty of General Dental Practice (UK) pioneered the development of radiographic selection criteria for dentistry in the UK in 1998 and followed this with a second edition in 2004. This year will see a third edition, updated by new research evidence and developments in X-ray imaging for dentistry, including cone beam computed tomography (CT). Radiographic selection criteria are not rules but are one form of clinical guideline designed to help in clinical decision making. There are many influences on the use of radiography in dental practice including non-clinical factors. Evidence-based radiographic selection criteria can help to reinforce good practice, but require a multi-faceted implementation strategy including incorporation into clinical audit, easy availability to users and education.

  15. Mycetoma revisited. Incidence of various radiographic signs.

    PubMed

    Abd El-Bagi, Mohamed E; Fahal, Ahmed H

    2009-04-01

    To define and quantitate various radiographic signs of mycetoma infection. A retrospective study of 516 randomly selected patients seen between December 1996 and December 2004 at the Mycetoma Research Centre of Khartoum University, Khartoum, Sudan. All cases were confirmed by clinical examination, initial pretreatment radiographs, and histopathology. The most common abnormalities in these 516 patients were soft tissue swelling (93%), bone sclerosis (56%), bone cavities (32%), and periosteal reaction (27%). The incidence of bone expansion (22%), extrinsic cortical scalloping (22%), and fanning of the rays in 10% were reported. Osteoporosis was seen in 19%. Only 3% of the patients had normal radiographs. Maximal scrutiny of radiographs alone by experienced radiologists is vital, as other imaging techniques are not available where mycetoma is prevalent.

  16. Solid state radiographic image amplifiers, part C

    NASA Technical Reports Server (NTRS)

    Szepesi, Z.

    1971-01-01

    The contrast sensitivity of the radiographic amplifiers, both the storage type and nonstorage type, their absolute sensitivity, and the reproducibility of fabrication were investigated. The required 2-2T quality level was reached with the radiographic storage screen. The sensitivity threshold was 100 to 200 mR with 45 to 100 kV filtered X-rays. The quality level of the radiographic amplifier screen (without storage) was 4-4T; for a 6 mm (0.25 in.) thick aluminum specimen, a 1 mm (0.040 in.) diameter hole in a 0.25 mm (0.010 in.) thick penetrameter was detected. Its sensitivity threshold was 2 to 6 mR/min. The developed radiographic screens are applicable for uses in nondestructive testing.

  17. Lead Scales for X-Radiographs

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Adams, James F.

    1987-01-01

    Indentations made by typing on lead tape. Lead scales for inclusion in x-radiographs as length and position references created by repeatedly imprinting character like upper-case I, L, or V, or lower-case L into lead tape with typewriter. Character pitch of typewriter serves as length reference for scale. Thinning of tape caused by impacts of type shows up dark in radiograph.

  18. The one-leg standing radiograph

    PubMed Central

    Naratrikun, K.; Kanitnate, S.; Sangkomkamhang, T.

    2016-01-01

    Objectives The purpose of this study was to compare the joint space width between one-leg and both-legs standing radiographs in order to diagnose a primary osteoarthritis of the knee. Methods Digital radiographs of 100 medial osteoarthritic knees in 50 patients were performed. The patients had undergone one-leg standing anteroposterior (AP) views by standing on the affected leg while a both-legs standing AP view was undertaken while standing on both legs. The severity of the osteoarthritis was evaluated using the joint space width and Kellgren-Lawrence (KL) radiographic classification. The t-test was used for statistical analysis. Results The mean medial joint space width found in the one-leg and in the both-legs standing view were measured at 1.8 mm and 2.4 mm, respectively (p < 0.001, 95% CI 0.5 to 0.7). 33%, 47.4% and 23.1% of the knees diagnosed with a KL grade of I, II and III in the both-legs standing views were changed to KL grade II, III and IV in the one-leg standing views, respectively. No changes for KL IV osteoarthritis diagnoses have been found between both- and one-leg standing views. Conclusions One-leg standing radiographs better represent joint space width than both-legs standing radiographs. 32% of both-legs standing radiographs have changed the KL grading to a more severe grade than that in the one-leg standing radiographs. Cite this article: P. Pinsornsak, K. Naratrikun, S. Kanitnate, T. Sangkomkamhang. The one-leg standing radiograph: An improved technique to evaluate the severity of knee osteoarthritis. Bone Joint Res 2016;5:436–441. DOI: 10.1302/2046-3758.59.BJR-2016-0049.R1. PMID:27683299

  19. Radiation recommendation series: administratively required dental radiographs

    SciTech Connect

    Not Available

    1981-09-01

    Administrative requirements for radiographs are found in many segments of the United States health care system. This document presents an FDA radiation recommendation on administratively required dental x-ray examinations. In general, such examinations are not requested to further the patient's dental health, but rather as a means of monitoring claims. However, the administrative use of radiographs that have been taken in the normal course of patient care is usually appropriate, as long as the patient's right to privacy is respected.

  20. A New Radiographic Corrosion Inspection Capability.

    DTIC Science & Technology

    1986-01-01

    significantly enhance the corrosion detection and damage assessment capabilities of a digital radiographic system. 2.0 PROGRAM DESCRIPTION Corrosion of...detection and assessment technology by applying dual-energy techniques to digital radiographic systems. 2.2 Program Objectives The overall objective of the...CODES 18. SUBJECT TERMS (Continue on reverse if necessary and identify by block number) FIELD GROUP SUB-GROUP dual energy photoelectric digital

  1. Lead Scales for X-Radiographs

    NASA Technical Reports Server (NTRS)

    Burley, Richard K.; Adams, James F.

    1987-01-01

    Indentations made by typing on lead tape. Lead scales for inclusion in x-radiographs as length and position references created by repeatedly imprinting character like upper-case I, L, or V, or lower-case L into lead tape with typewriter. Character pitch of typewriter serves as length reference for scale. Thinning of tape caused by impacts of type shows up dark in radiograph.

  2. Group-invariant solutions of hydrodynamics and radiation hydrodynamics

    SciTech Connect

    Coggeshall, S.V.

    1993-08-01

    Using the property of invariance under Lie groups of transformations, the equations of hydrodynamics are transformed from partial differential equations to ordinary differential equations, for which special analytic solutions can be found. These particular solutions can be used for (1) numerical benchmarks, (2) the basis for analytic models, and (3) insight into more general solutions. Additionally, group transformations can be used to construct new solutions from existing ones. A space-time projective group is used to generate complicated solutions from simpler solutions. Discussion of these procedures is presented along with examples of analytic of 1,2 and 3-D hydrodynamics.

  3. Vertical axis wind turbines

    DOEpatents

    Krivcov, Vladimir [Miass, RU; Krivospitski, Vladimir [Miass, RU; Maksimov, Vasili [Miass, RU; Halstead, Richard [Rohnert Park, CA; Grahov, Jurij [Miass, RU

    2011-03-08

    A vertical axis wind turbine is described. The wind turbine can include a top ring, a middle ring and a lower ring, wherein a plurality of vertical airfoils are disposed between the rings. For example, three vertical airfoils can be attached between the upper ring and the middle ring. In addition, three more vertical airfoils can be attached between the lower ring and the middle ring. When wind contacts the vertically arranged airfoils the rings begin to spin. By connecting the rings to a center pole which spins an alternator, electricity can be generated from wind.

  4. Single Axis Piezoceramic Gimbal

    NASA Technical Reports Server (NTRS)

    Horner, Garnett C.; Taleghani, Barmac K.

    1999-01-01

    This paper describes the fabrication, testing, and analysis of a single axis piezoceramic gimbal. The fabrication process consist of pre-stressing a piezoceramic wafer using a high-temperature thermoplastic polyimide and a metal foil. The differential thermal expansion between the ceramic and metal induces a curvature. The pre-stressed, curved piezoceramic is mounted on a support mechanism and a mirror is attached to the piezoceramic. A plot of gimbal angle versus applied voltage to the piezoceramic is presented. A finite element analysis of the piezoceramic gimbal is described. The predicted gimbal angle versus applied voltage is compared to experimental results.

  5. Maxwell-Chern-Simons hydrodynamics for the chiral magnetic effect

    SciTech Connect

    Oezoender, Sener

    2010-06-15

    The rate of vacuum-changing topological solutions of the gluon field, sphalerons, is estimated to be large at the typical temperatures of heavy-ion collisions, particularly at the Relativistic Heavy Ion Collider. Such windings in the gluon field are expected to produce parity-odd bubbles, which cause separation of positively and negatively charged quarks along the axis of the external magnetic field. This chiral magnetic effect can be mimicked by Chern-Simons modified electromagnetism. Here we present a model of relativistic hydrodynamics including the effects of axial anomalies via the Chern-Simons term.

  6. How entropy and hydrodynamics cooperate in rectifying particle transport

    NASA Astrophysics Data System (ADS)

    Martens, S.; Schmid, G.; Straube, A. V.; Schimansky-Geier, L.; Hänggi, P.

    2013-10-01

    Using the analytical Fick-Jacobs approximation formalism and extensive Brownian dynamics simulations we study particle transport through two-dimensional periodic channels with triangularly shaped walls. Directed motion is caused by the interplay of constant bias acting along the channel axis and a pressure-driven flow. In particular, we analyze the particle mobility and the effective diffusion coefficient. The mechanisms of entropic rectification is revealed in channels with a broken spatial reflection symmetry in presence of hydrodynamically enforced entropic trapping. Due to the combined action of the forcing and the pressure-driven flow field, efficient rectification with a drastically reduced diffusivity is achieved.

  7. Effect of truncated cone roughness element density on hydrodynamic drag

    NASA Astrophysics Data System (ADS)

    Womack, Kristofer; Schultz, Michael; Meneveau, Charles

    2016-11-01

    An experimental study was conducted on rough-wall, turbulent boundary layer flow. Varying planform densities of truncated cone roughness elements were investigated. Element densities studied ranged from 10% to 57%. Detailed turbulent boundary layer velocity statistics were recorded with a two-component LDV system on a three-axis traverse. Hydrodynamic roughness length (z0) and skin-friction coefficient (Cf) were determined and compared with the estimates from existing roughness element drag prediction models including Macdonald et al. (1998) and Yang et al. (2015). The roughness elements used in this work model idealized barnacles, so implications of this data set for ship powering are considered. Office of Naval Research.

  8. Radiographic signs and diagnosis of dental disease.

    PubMed

    Bellows, J

    1993-08-01

    Dental radiographs are critical for the complete assessment and treatment of dental diseases. Dental radiography is commonly used to evaluate congenital dental defects, periodontal disease, orthodontic manipulations, oral tumors, endodontic treatments, oral trauma, and any situation where an abnormality is suspected. Although standard radiographic equipment and film can be used to produce dental radiographs, dental X-ray equipment and film provide superior quality images and greater convenience of animal patient positioning. An understanding of normal dental radiographic anatomy is important when interpreting dental radiographs. Stage III periodontitis is the earliest stage of periodontal disease at which radiographic abnormalities become apparent. Bone loss associated with periodontal disease can be classified as either horizontal or vertical. Periapical radiolucencies can represent granulomas, cysts, or abscesses, whereas periapical radiodensities may represent sclerotic bone or condensing osteitis. Lytic lesions of the bone of the jaw often represent oral neoplasms. Neoplasms also can displace or disrupt teeth in the dental arch. Resorptive lesions can be external or internal and appear as radiolucent areas involving the external surface of the root or the pulp cavity, respectively. Feline dental resorptive lesions, also known as odontoclastic resorptions, are a specific form of dental resorptive lesions unique to cats.

  9. Hydrodynamic shocks in microroller suspensions

    NASA Astrophysics Data System (ADS)

    Delmotte, Blaise; Driscoll, Michelle; Chaikin, Paul; Donev, Aleksandar

    2017-09-01

    We combine experiments, large-scale simulations, and continuum models to study the emergence of coherent structures in a suspension of magnetically driven microrollers sedimented near a floor. Collective hydrodynamic effects are predominant in this system, leading to strong density-velocity coupling. We characterize a uniform suspension and show that density waves propagate freely in all directions in a dispersive fashion. When sharp density gradients are introduced in the suspension, we observe the formation of a shock. Unlike Burgers' shocklike structures observed in other active and driven confined hydrodynamic systems, the shock front in our system has a well-defined finite width and moves rapidly compared to the mean suspension velocity. We introduce a continuum model demonstrating that the finite width of the front is due to far-field nonlocal hydrodynamic interactions and governed by a geometric parameter, the average particle height above the floor.

  10. Numerical Hydrodynamics in Special Relativity.

    PubMed

    Martí, José Maria; Müller, Ewald

    2003-01-01

    This review is concerned with a discussion of numerical methods for the solution of the equations of special relativistic hydrodynamics (SRHD). Particular emphasis is put on a comprehensive review of the application of high-resolution shock-capturing methods in SRHD. Results of a set of demanding test bench simulations obtained with different numerical SRHD methods are compared. Three applications (astrophysical jets, gamma-ray bursts and heavy ion collisions) of relativistic flows are discussed. An evaluation of various SRHD methods is presented, and future developments in SRHD are analyzed involving extension to general relativistic hydrodynamics and relativistic magneto-hydrodynamics. The review further provides FORTRAN programs to compute the exact solution of a 1D relativistic Riemann problem with zero and nonzero tangential velocities, and to simulate 1D relativistic flows in Cartesian Eulerian coordinates using the exact SRHD Riemann solver and PPM reconstruction.

  11. Vertical axis wind turbine

    SciTech Connect

    Cubbers, J.

    1993-07-13

    A vertical axis wind turbine is described comprising: a vertically extending axle supported for rotation about a vertical axis; a series of wind vanes arranged around said axle; support means supporting each of said wind vanes on said axle, each of said wind vanes comprising a substantially flat main panel section of flexible material draped vertically by said support means to extend in a circumferential direction; each of said wind vanes including at least one pocket comprised of a substantially flat overlayer panel of flexible material overlying the outside of said wind vane flexible material panel section and attached thereto along a vertical side by a seam and also attached thereto along the top and bottom, but unattached along the other side to form a normally closed pocket which is able to flare open when wind is blowing from the unattached side thereof and thereby catch said wind, said pocket collapsing when wind blows from the attached side of said overlayer by said overlayer panel again overlying said main panel section.

  12. Fibromyxoma of the axis.

    PubMed

    Mavrogenis, Andreas F; Casadei, Roberto; Gambarotti, Marco; Ruggieri, Pietro

    2012-07-01

    Fibromyxoma of bone is a rare benign tumor of fibrous tissue origin. The typical location is the jaws. Sporadic extragnathic cases have been reported, but fibromyxoma of the spine has not been reported. The histological appearance of fibromyxoma is benign and includes abundant extracellular fibrous and myxoid stroma with varying amounts of calcification and ossification. Myxoid changes are usually extensive. Extragnathic fibromyxoma of bone should be distinguished from benign cartilage-forming bone tumors, such as chondromyxoid and myxoid chondrosarcoma and myxoma of bone. It has also been suggested that fibromyxoma is a variant of myxoid fibrous dysplasia, whereas other authors reported extragnathic fibromyxoma resulting from myxoid degeneration of bone tumors, such as chondrosarcoma or fibrosarcoma. The overtreatment of patients with fibromyxoma of bone due to an aggressive imaging appearance should be avoided; the prognosis is excellent compared with the jaw variant and depends on the location and extent of the tumor. This article describes a case of a 21-year-old woman with fibromyxoma of bone originating from the spinous process of the axis. Clinical examination showed a tender mass in the midline of the posterior aspect the neck and slight limitation of neck range of motion; neurologic examination was normal. Diagnosis was obtained with a preoperative biopsy. Marginal excision of the lesion with posterior laminectomy of the axis was performed. The facets were preserved, and no fusion was performed. At last follow-up 2 years after diagnosis and treatment, the patient was asymptomatic with no evidence of local recurrence.

  13. Radiographic Study of Pes Planovarus.

    PubMed

    Aebi, Janic; Horisberger, Monika; Frigg, Arno

    2017-05-01

    Depending on the direction of the subtalar joint, a foot deformity generally tends towards pronation (pes planovalgus) or supination (pes cavovarus). However, the combination of hindfoot varus and flat midfoot/forefoot (pes planovarus) is an exception to this rule. Pes planovarus has so far only been referred to in connection with Müller-Weiss disease and congenital disease. We diagnosed pes planovarus in otherwise healthy patients without these diseases. Forty patients with 54 symptomatic feet who were treated between August 2012 and July 2016 were included (mean age, 44.1 ± 15.7 years; 15 male/25 female). They were selected from 1064 consecutive cases (3.8%). Inclusion criteria were hindfoot varus and flat midfoot/forefoot. Their symptoms, radiographs, and therapies within the first 3 months were retrospectively analyzed. The position in the hindfoot alignment view (HAV), talometatarsal-1 angle lateral (TMT1lat) and dorsoplantar (TMT1dp), talocalcaneal angle lateral (TCAlat) and dorsoplantar (TCAdp), and calcaneal pitch angle (CPA) were measured on a DICOM/PACS system. The mean radiological results (standard values from the literature in brackets) were as follows: the hindfoot was significantly in varus in the HAV (-6.9 ± 3.6 mm [-1.6 ± 7.2 mm]; P < .001), the TMT1lat was significantly flatter (-6.7 ± 5.8 degrees [8.4 ± 5.9 degrees]; P < .001), the TMT1dp was significantly less in abduction (1.5 ± 7.9 degrees [7.7 ± 8.2 degrees]; P = .005), the TCAdp showed no difference (25.9 ± 7.9 degrees [24.1 ± 5.7 degrees]; P = .118), the TCAlat was significantly larger (47.5 ± 6.1 degrees [43.4 ± 7.1 degrees]; P < .001), and the CPA was significantly flatter (17.6 ± 3.9 degrees [24.5 ± 3.0 degrees]; P < .001). The most frequent symptoms were stress-induced foot pain (n = 33), hallux valgus (n = 20), chronic ankle instability (n = 17), metatarsalgia (n = 15), chronic midfoot pain (n = 13), heel pain (n = 12), and lesser toe deformities (n = 8). Thirty-one feet

  14. Abnormal pressures as hydrodynamic phenomena

    USGS Publications Warehouse

    Neuzil, C.E.

    1995-01-01

    So-called abnormal pressures, subsurface fluid pressures significantly higher or lower than hydrostatic, have excited speculation about their origin since subsurface exploration first encountered them. Two distinct conceptual models for abnormal pressures have gained currency among earth scientists. The static model sees abnormal pressures generally as relict features preserved by a virtual absence of fluid flow over geologic time. The hydrodynamic model instead envisions abnormal pressures as phenomena in which flow usually plays an important role. This paper develops the theoretical framework for abnormal pressures as hydrodynamic phenomena, shows that it explains the manifold occurrences of abnormal pressures, and examines the implications of this approach. -from Author

  15. Hydrodynamic interactions in protein folding

    NASA Astrophysics Data System (ADS)

    Cieplak, Marek; Niewieczerzał, Szymon

    2009-03-01

    We incorporate hydrodynamic interactions (HIs) in a coarse-grained and structure-based model of proteins by employing the Rotne-Prager hydrodynamic tensor. We study several small proteins and demonstrate that HIs facilitate folding. We also study HIV-1 protease and show that HIs make the flap closing dynamics faster. The HIs are found to affect time correlation functions in the vicinity of the native state even though they have no impact on same time characteristics of the structure fluctuations around the native state.

  16. Hydrodynamic behavior of fractal aggregates

    NASA Astrophysics Data System (ADS)

    Wiltzius, Pierre

    1987-02-01

    Measurements of the radius of gyration RG and the hydrodynamic radius RH of colloidal silica aggregates are reported. These aggregates have fractal geometry and RH is proportional to RG for 500 Å<=RH<=7000 Å, with a ratio RH/RG=0.72+/-0.02. The results are compared with predictions for macromolecules of various shapes. The proportionality of the two radii can be understood with use of the pair correlation function of fractal objects and hydrodynamic interactions on the Oseen level. The value of the ratio remains to be explained.

  17. Relativistic hydrodynamics of cosmological sheets

    SciTech Connect

    Anninos, P. ); McKinney, J. )

    1999-09-01

    We have extended previous numerical calculations of Newtonian cosmological sheets to include self-consistent interactions with the background metric by solving the complete Einstein field equations together with the relativistic perfect fluid hydrodynamics equations. The initial data are parametrized and constructed using the gauge invariant perturbation formalism to specify the free conformal variables for the constraints. Numerical evolutions of initially horizon scale fluctuations are compared with results from perturbation theory and the Zel[close quote]dovich solution for a range of gravitational field strengths, and we discuss the nonlinear hydrodynamic, optical, and geometric characteristics of the sheet structures. [copyright] [ital 1999] [ital The American Physical Society

  18. Hydrodynamic stability of rockets with headwall injection

    NASA Astrophysics Data System (ADS)

    Abu-Irshaid, Esam M.; Majdalani, Joseph; Casalis, Grégoire

    2007-02-01

    We investigate the hydrodynamic instability of the full-length, cylindrical models of solid and hybrid rockets with headwall injection. Our baseline is the rotational incompressible flowfield proposed in a recent study (Majdalani and Vyas, "Inviscid models of the classic hybrid rocket," AIAA Paper 2004-3474). The local nonparallel approach is implemented in which the amplitude functions are assumed to be radially dependent at fixed streamwise locations. The usual singularity along the chamber axis is eliminated using Taylor series expansions. As a result, three compatibility relations are derived and substituted for the local boundary conditions along the axis. These depend on whether the tangential wave number q is 0, 1, or larger. Our rotational model is shown to exhibit a range of instability that broadens with successive increases in headwall injection. The lowest frequency below which the flow remains unconditionally stable is observed at ω =28.5 regardless of the headwall injection rate. As usual, the zeroth order tangential mode is found to be the most amplified. Using a representative headwall injection velocity for hybrid rockets, we identify a range of frequencies along which large excursions in pressure and velocity amplitudes are possible. These surges signal the presence of a resonant-like mechanism that is akin to an acoustic instability response. The most excited frequencies vary between 387 and 415 in the vicinity of the headwall. These frequencies are spatially delayed and lowered to 93.8-163.5 when the headwall injection rate is reduced to the level associated with solid rockets. For the most critical streamwise stations, these resurging wave amplitudes are quantified and shown to exhibit spectra that mimic the waterfall data acquired in acoustic instability tests.

  19. Is clinical measurement of anatomic axis of the femur adequate?

    PubMed

    Wu, Chi-Chuan

    2017-08-01

    Background and purpose - The accuracy of using clinical measurement from the anterior superior iliac spine (ASIS) to the center of the knee to determine an anatomic axis of the femur has rarely been studied. A radiographic technique with a full-length standing scanogram (FLSS) was used to assess the adequacy of the clinical measurement. Patients and methods - 100 consecutive young adult patients (mean age 34 (20-40) years) with chronic unilateral lower extremity injuries were studied. The pelvis and intact contralateral lower extremity images in the FLSS were selected for study. The angles between the tibial axis and the femoral shaft anatomic axis (S-AA), the piriformis anatomic axis (P-AA), the clinical anatomic axis (C-AA), and the mechanical axis (MA) were compared between sexes. Results - Only the S-AA and C-AA angles were statistically significantly different in the 100 patients (3.6° vs. 2.8°; p = 0.03). There was a strong correlation between S-AA, P-AA, and C-AA angles (r > 0.9). The average intersecting angle between MA and S-AA in the femur in the 100 patients was 5.5°, and it was 4.8° between MA and C-AA. Interpretation - Clinical measurement of an anatomic axis from the ASIS to the center of the knee may be an adequate and acceptable method to determine lower extremity alignment. The optimal inlet for antegrade femoral intramedullary nailing may be the lateral edge of the piriformis fossa.

  20. Reducing missing fracture clinic radiographs by entrusting them to patients.

    PubMed Central

    Calder, Peter R.; Hynes, Matthew C.; Goodier, W. David

    2004-01-01

    BACKGROUND: Missing radiographs in fracture clinics may compromise fracture management and lead to inappropriate use of clerical resources. METHODS: We prospectively compared the number of missing radiographs in two hospitals over a period of two months. In hospital A the radiographs were retained and in hospital B they were entrusted to the patients. RESULTS: At the completion of the study, entrusting patients with their radiographs resulted in statistically less radiographs missing from the clinic. PMID:15333169

  1. An Anatomic Study on Whether the Immature Patella is Centered on an Anteroposterior Radiograph.

    PubMed

    Kyriakedes, James C; Liu, Raymond W

    2017-03-01

    In the operating room, after first obtaining a proper lateral radiograph with the condyles superimposed, a 90-degree rotation of the intraoperative fluoroscopy unit does not always produce an anteroposterior (AP) image with the patella centered. The orthogonality of these 2 views has not been well determined in children. This study was comprised of a radiographic group (35 knees) and a cadaveric group (59 knees). Both cadaveric and clinical images were obtained by resting or positioning the femur with the posterior condyles overlapped, and then taking an orthogonal AP image. Centering of the patella was calculated and multiple regression analysis was performed to determine the relationship between patellar centering and age, sex, ethnicity, mechanical lateral distal femoral angle (mLDFA), medial proximal tibial angle (MPTA), and contralateral centering. Mean patellar centering, expressed as the lateral position of the patella with respect to the total condylar width, was 0.08±0.10 in the radiographic group and 0.06±0.03 in the cadaveric group. Positive (lateral) patellar centering in 1 knee had a statistically significant correlation with positive patellar centering in the contralateral knee in both the radiographs and the cadavers. In the radiographic group, there was a statistically significant correlation between femoral varus and valgus deformities and positive patellar centering. In the cadaveric group, there was a statistically significant correlation between tibial valgus and negative (medial) patellar centering. The patella in an immature knee is rarely perfectly centered on a true AP image, and is usually seated slightly laterally within the femoral condyles. Obtaining a true AP intraoperative radiograph is critical to analyzing and correcting valgus and varus deformities, and in the proper placement of implants. When addressing knee deformity one should consider obtaining an AP view orthogonal either to a perfect lateral of the knee or orthogonal to the

  2. Hydrodynamically mediated macrophyte silica dynamics.

    PubMed

    Schoelynck, J; Bal, K; Puijalon, S; Meire, P; Struyf, E

    2012-11-01

    In most aquatic ecosystems, hydrodynamic conditions are a key abiotic factor determining species distributions and abundance of aquatic plants. Resisting stress and keeping an upright position often relies on investment in tissue reinforcement, which is costly to produce. Silica could provide a more economical alternative. Two laboratory experiments were conducted to measure the response of two submerged species, Egeria densa Planch. and Limnophila heterophylla (Roxb.) Benth., to dissolved silicic acid availability and exposure to hydrodynamic stress. The results were verified with a third species in a field study (Nuphar lutea (L.) Smith). Biogenic silica (BSi) concentration in both stems and leaves increases with increasing dissolved silica availability but also with the presence of hydrodynamic stress. We suggest that the inclusion of extra silica enables the plant to alternatively invest its energy in the production of lignin and cellulose. Although we found no significant effects of hydrodynamic stress on cellulose or lignin concentrations either in the laboratory or in the field, BSi was negatively correlated with cellulose concentration and positively correlated with lignin concentration in samples collected in the field study. This implies that the plant might perform with equal energy efficiency in both standing and running water environments. This could provide submerged species with a tool to respond to abiotic factors, to adapt to new ecological conditions and hence potentially colonise new environments. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

  3. Softened Lagrangian hydrodynamics for cosmology

    NASA Astrophysics Data System (ADS)

    Gnedin, Nickolay Y.

    1995-04-01

    A new approach to cosmological hydrodynamics is discussed that is based on a moving, quasi-Lagrangian mesh. The softened Lagrangian hydrodynamics (SLH) method utilizes a high-resolution Lagrangian hydrodynamic code combined with a low-resolution Eulerian solver to deal with severe mesh distortions. Most of the volume of a simulation is treated with the Lagrangian code and only in sites where the Lagrangian approach fails, due to mesh distortions, does the Eulerian part of the code step in. This approach utilizes a high-resolution gravity solver without use of TREE or P3M methods; Poisson's equation is solved on the moving baryonic mesh using a simple relaxation technique. The dark matter is included by means of the cloud-in-cell method on the Lagrangian mesh. All three components of the cosmological code--gravity, dark matter, and baryons--are thus treated selft-consistently with exactly the same resolution. The computer code based on the SLH approach is described in detail, and comparison with existing Eulerian and smooth particle hydrodynamics (SPH) codes is presented. For most purposes the SLH approach turns out to be the intermediate between Eulerian and SPH codes, but it outperforms both of these approaches in resolving caustics. Thus, it may turn out to be a valuable tool to study galaxy formation.

  4. Hydrodynamic slip in silicon nanochannels

    NASA Astrophysics Data System (ADS)

    Ramos-Alvarado, Bladimir; Kumar, Satish; Peterson, G. P.

    2016-03-01

    Equilibrium and nonequilibrium molecular dynamics simulations were performed to better understand the hydrodynamic behavior of water flowing through silicon nanochannels. The water-silicon interaction potential was calibrated by means of size-independent molecular dynamics simulations of silicon wettability. The wettability of silicon was found to be dependent on the strength of the water-silicon interaction and the structure of the underlying surface. As a result, the anisotropy was found to be an important factor in the wettability of these types of crystalline solids. Using this premise as a fundamental starting point, the hydrodynamic slip in nanoconfined water was characterized using both equilibrium and nonequilibrium calculations of the slip length under low shear rate operating conditions. As was the case for the wettability analysis, the hydrodynamic slip was found to be dependent on the wetted solid surface atomic structure. Additionally, the interfacial water liquid structure was the most significant parameter to describe the hydrodynamic boundary condition. The calibration of the water-silicon interaction potential performed by matching the experimental contact angle of silicon led to the verification of the no-slip condition, experimentally reported for silicon nanochannels at low shear rates.

  5. Radiation awareness among dentists, radiographers and students.

    PubMed

    Furmaniak, Katarzyna Z; Kołodziejska, Marzena A; Szopiński, Kazimierz T

    2016-10-01

    The aim of this study was to assess radiation awareness among dentists, radiographers, dentistry students and radiography students from the Medical University of Warsaw. A questionnaire containing 13 multiple-choice questions was administered to 200 dentists, 200 radiographers, 100 dentistry students and 100 radiography students. Participants were asked about basic knowledge concerning dental radiological examinations. In total, 301 (50.2%) questionnaires were returned. The mean score of correct answers was 8.13 out of 13 for all responders; 8.36 for dentists, 8.11 for radiographers, 8.19 for dentistry students and 7.46 for radiography students. Range of correct answers varied from 3 to 12. Differences between the four main groups were not statistically significant. Dentists who had completed radiation protection training had significantly higher number of correct answers than untrained dentists. For radiographers, the level of education had no connection with the results. Correlation between year of the study and results was not visible in the dentistry student group. Within the radiography student group, students in the third year of the study had significantly higher number of correct answers than those in the first and second years of the study. Our survey shows that radiation awareness among dentists, radiographers and students is inadequate, without significant differences in the main groups. Dentists who had completed radiation protection training had better awareness than those without such training. Greater emphasis should be put on the dental radiology course in both dentistry and radiography programmes at universities.

  6. Imaging x-ray fluorescence relevant to hydrodynamic mixing experiments at the National Ignition Facility

    NASA Astrophysics Data System (ADS)

    MacDonald, Michael; Gamboa, Eliseo; Kuranz, Carolyn; Keiter, Paul; Drake, R. Paul

    2012-10-01

    The National Ignition Facility (NIF) is capable of providing enough energy to explore areas of physics that are not possible on any previous laser system. This includes large-volume, geometrically complex hydrodynamic and radiation hydrodynamic experiments in which traditional, line-integrated radiographic techniques limit the quality of the results. As an example, we are involved in divergent hydrodynamic experiments at the NIF, motivated by supernova hydrodynamics, that cannot be diagnosed in detail with transmission radiography. X-ray scattering has been considered for this purpose and appears feasible [1]. Here we consider fluorescence imaging, a better candidate as the cross section of photoabsorption in the several-keV range is roughly 100 times larger than that of scattering. A single layer of the target will be uniformly doped with a fluorescent tracer, which will be pumped by a sheet of x-rays. The fluorescent intensity will be measured to create a density map of the doped material as it mixes with other layers. Developing this diagnostic will create a powerful tool to characterize hydrodynamic experiments with complex geometries.[4pt] [1] Huntington et al. High Energy Density Physics 6, 194 (2010).

  7. Numerical simulation of hydrodynamic flows in the jet electric

    NASA Astrophysics Data System (ADS)

    Sarychev, V. D.; Granovskii, A. Yu; Nevskii, S. A.

    2016-02-01

    On the basis of concepts from magnetic hydrodynamics the mathematical model of hydrodynamic flows in the stream of electric arc plasma, obtained between the rod electrode and the target located perpendicular to the flat conductive, was developed. The same phenomenon occurs in the welding arc, arc plasma and other injection sources of charged particles. The model is based on the equations of magnetic hydrodynamics with special boundary conditions. The obtained system of equations was solved by the numerical method of finite elements with an automatic selection of the time step. Calculations were carried out with regard to the normal plasma inleakage on the solid conducting surface and the surface with the orifice. It was found that the solid surface facilitates three swirling zones. Interaction of these zones leads to the formation of two stable swirling zones, one of which is located at a distance of two radii from the axis and midway between the electrodes, another is located in the immediate vicinity of the continuous electrode. In this zone plasma backflow scattering fine particles is created. Swirling zones are not formed by using the plane electrode with an orifice. Thus, the fine particles can pass through it and consolidate.

  8. A radiographic scanning technique for cores

    USGS Publications Warehouse

    Hill, G.W.; Dorsey, M.E.; Woods, J.C.; Miller, R.J.

    1979-01-01

    A radiographic scanning technique (RST) can produce single continuous radiographs of cores or core sections up to 1.5 m long and up to 30 cm wide. Changing a portable industrial X-ray unit from the normal still-shot mode to a scanning mode requires simple, inexpensive, easily constructed, and highly durable equipment. Additional components include a conveyor system, antiscatter cylinder-diaphragm, adjustable sample platform, developing tanks, and a contact printer. Complete cores, half cores, sample slabs or peels may be scanned. Converting the X-ray unit from one mode to another is easy and can be accomplished without the use of special tools. RST provides the investigator with a convenient, continuous, high quality radiograph, saves time and money, and decreases the number of times cores have to be handled. ?? 1979.

  9. Centric relation determinations: clinical and radiographic comparisons.

    PubMed

    Carwell, M L; McFall, W T

    1981-07-01

    This study investigated variations in occlusal prematurities and condylar positions using different methods of determining centric relation. Thirty patients were randomly placed into three groups of 10. In Group I a clinical analysis of occlusal patterns using bilateral mandibular manipulation (BMM) was compared to results with a chin point (CPM) method. Group II compared CPM to an anterior guidance jig (CPJ) method. Group III compared BMM to CPJ. Standardized transcranial oblique radiographs were taken of each temporomandibular joint using CPM and BMM on 10 patients. Condylar position was determined with tracing evaluations and direct measurements of the radiographs. Clinical results indicated that the initial point of contact was located most accurately with CPJ. Both initial contact points and secondary points were disclosed with CPM. The BMM disclosed the most tooth contacts. Contacts were most prevalent on the premolars. Radiographic analyses of condylar positions were inconclusive.

  10. Radiographic visualization of intraosseous Thorotrast in vivo

    SciTech Connect

    Arndt, J.H.; Hosford, G.; Kingsley, W.B.; Tillery, G.W.; Gaulden, M.E.

    1980-02-01

    The carcinogenic effects of residual Thorotrast in human tissues makes recognition of its various radiographic patterns important. Most radiologists are familiar with the appearance of the liver, spleen, and upper abdominal lymph nodes after intravascular injection of the colloidal suspension. Radiographic visualization of intraosseous Thorotrast deposits in the living patient has not, to our knowledge, been reported. An estimated 1% to 10% of intravascularly administered Thorotrast is ultimately sequestered by the reticuloendothelial system of cancellous bone. Since the radiographic density of normal bone is high, and the quantity of thorium per unit volume of bone low, it would not seem possible to detect Thorotrast deposits in normal bone. However, the colloidal materials is picked up by bone histiocytes that tend to aggregate into clusters. Against a background of demineralized bone, these aggregates (or summation thereof) become visible.

  11. Postmortem abdominal radiographic findings in feline cadavers.

    PubMed

    Heng, Hock Gan; Teoh, Wen Tian; Sheikh-Omar, Abdul Rahman

    2008-01-01

    Postmortem radiographic examinations of animals are commonly performed in judicial investigations to rule out gunshot and fractures. However, there was no available data on radiographic postmortem changes of animals. Forty-one sets of abdominal radiographs of feline cadavers made within 12 h of death were evaluated for postmortem changes. Intravascular gas was detected in 11 of 41 (27%) cadavers. The most common site of intravascular gas was the liver. Intravascular gas was also present in the aorta, femoral artery, celiac and cranial mesenteric arteries, and caudal superficial epigastric artery. Intrasplenic gas was detected in two cadavers. Only two cadavers had distended small intestine. One cadaver had pneumatosis coli. The changes detected were most likely due to putrefaction.

  12. Factors affecting radiographic progression of knee osteoarthritis.

    PubMed

    Ledingham, J; Regan, M; Jones, A; Doherty, M

    1995-01-01

    To evaluate the prognostic significance of patient characteristics and radiographic features at the knee for outcome of knee osteoarthritis. This was a prospective observational study of 350 osteoarthritic knees. Clinical and radiographic data were obtained on 188 hospital referred patients (mean age 70, range 34-91 years). Median duration of follow up was two years (range 1-5 years). The majority of patients (48%) reported deterioration, but 23% experienced improvement in symptoms during the study period. Reported exercise tolerance remained unchanged in the majority (62%) and deteriorated in 35%. Change in at least one individual radiographic feature of osteoarthritis was seen in 252 (72%) knees: increase in joint space narrowing occurred in 52%, osteophyte in 32%, cysts in 19%, sclerosis in 14%, and attrition in 30%. Increase in Kellgren grade occurred in 137 (39%) knees. Knee effusion, osteoarthritis at multiple joint sites, and nodal change associated with change in Kellgren grade (odds ratios 1.03, 2.39, and 1.80; 95% confidence intervals (CI) 1.01 to 1.05, 1.16 to 4.93, and 1.02 to 3.17, respectively); warmth at the knee associated with change in any radiographic feature (odds ratio 2.22; 95% CI 1.19 to 4.14). Development of, or increase in, attrition and joint space narrowing associated with worsening symptoms and function and occurred with increased frequency in knees with effusions, clinical warmth and calcium pyrophosphate crystals in synovial fluid (p < 0.05). A high rate of change, radiographic more than clinical, was seen in osteoarthritic knees during this study. Poor clinical and radiographic outcome associated with calcium pyrophosphate crystal deposition and clinical inflammation as reflected by knee effusion and warmth.

  13. Method of radiographic inspection of wooden members

    NASA Technical Reports Server (NTRS)

    Berry, Maggie L. (Inventor); Berry, Robert F., Jr. (Inventor)

    1990-01-01

    The invention is a method to be used for radiographic inspection of a wooden specimen for internal defects which includes the steps of introducing a radiopaque penetrant into any internal defects in the specimen through surface openings; passing a beam of radiation through a portion of the specimen to be inspected; and making a radiographic film image of the radiation passing through the specimen, with the radiopaque penetrant in the specimen absorbing the radiation passing through it, thereby enhancing the resulting image of the internal defects in the specimen.

  14. Pelvic radiograph in skeletal dysplasias: An approach

    PubMed Central

    Jana, Manisha; Nair, Nikhil; Gupta, Arun K; Kabra, Madhulika; Gupta, Neerja

    2017-01-01

    The bony pelvis is constituted by the ilium, ischium, pubis, and sacrum. The pelvic radiograph is an important component of the skeletal survey performed in suspected skeletal dysplasia. Most of the common skeletal dysplasias have either minor or major radiological abnormalities; hence, knowledge of the normal radiological appearance of bony pelvis is vital for recognizing the early signs of various skeletal dysplasias. This article discusses many common and some uncommon radiological findings on pelvic radiographs along with the specific dysplasia in which they are seen; common differential diagnostic considerations are also discussed. PMID:28744080

  15. Validation of a new radiographic protocol for Asian elephant feet and description of their radiographic anatomy.

    PubMed

    Mumby, C; Bouts, T; Sambrook, L; Danika, S; Rees, E; Parry, A; Rendle, M; Masters, N; Weller, R

    2013-10-05

    Foot problems are extremely common in elephants and radiography is the only imaging method available but the radiographic anatomy has not been described in detail. The aims of this study were to develop a radiographic protocol for elephant feet using digital radiography, and to describe the normal radiographic anatomy of the Asian elephant front and hind foot. A total of fifteen cadaver foot specimens from captive Asian elephants were radiographed using a range of projections and exposures to determine the best radiographic technique. This was subsequently tested in live elephants in a free-contact setting. The normal radiographic anatomy of the Asian elephant front and hind foot was described with the use of three-dimensional models based on CT reconstructions. The projection angles that were found to be most useful were 65-70° for the front limb and 55-60° in the hind limb. The beam was centred 10-15 cm proximal to the cuticle in the front and 10-15 cm dorsal to the plantar edge of the sole in the hind foot depending on the size of the foot. The protocol developed can be used for larger-scale diagnostic investigations of captive elephant foot disorders, while the normal radiographic anatomy described can improve the diagnostic reliability of elephant feet radiography.

  16. Anomalous hydrodynamics of fractional quantum Hall states

    SciTech Connect

    Wiegmann, P.

    2013-09-15

    We propose a comprehensive framework for quantum hydrodynamics of the fractional quantum Hall (FQH) states. We suggest that the electronic fluid in the FQH regime can be phenomenologically described by the quantized hydrodynamics of vortices in an incompressible rotating liquid. We demonstrate that such hydrodynamics captures all major features of FQH states, including the subtle effect of the Lorentz shear stress. We present a consistent quantization of the hydrodynamics of an incompressible fluid, providing a powerful framework to study the FQH effect and superfluids. We obtain the quantum hydrodynamics of the vortex flow by quantizing the Kirchhoff equations for vortex dynamics.

  17. Usefulness of Chest Radiographs for Scoliosis Screening: A Comparison with Thoraco-Lumbar Standing Radiographs

    PubMed Central

    Oh, Chang Hyun; Kim, Chan Gyu; Lee, Myoung Seok; Park, Hyeong-Chun; Park, Chong Oon

    2012-01-01

    Purpose The purposes of this study were to evaluate the usefulness and limitations of chest radiographs in scoliosis screening and to compare these results with those of thoraco-lumbar standing radiographs (TLSR). Materials and Methods During Korean conscription, 419 males were retrospectively examined using both chest radiographs and TLSR to confirm the scoliosis and Cobb angle at the Regional Military Manpower. We compared the types of spinal curves and Cobb angles as measured from different radiographs. Results In the pattern of spinal curves, the overall matching rate of chest radiographs using TLSR was about 58.2% (244 of 419 cases). Cobb angle differences between chest radiographs and TLSR with meaningful difference was observed in 156 cases (37.2%); a relatively high proportion (9.5%) of Cobb angle differences more than 10 degrees was also observed. The matching rate of both spinal curve types and Cobb angle accuracy between chest radiographs and TLSR was 27.9% (117 among 419 cases). Chest radiographs for scoliosis screening were observed with 93.94% of sensitivity and 61.67% of specificity in thoracic curves; however, less than 40% of sensitivity (38.27%, 20.00%, and 25.80%) and more than 95% of specificity (97.34%, 99.69%, and 98.45%) were observed in thoraco-lumbar, lumbar, and double major curves, respectively. Conclusion The accuracy of chest radiographs for scoliosis screening was low. The incidence of thoracic curve scoliosis was overestimated and lumbar curve scoliosis was easily missed by chest radiography. Scoliosis screening using chest radiography has limited values, nevertheless, it is useful method for detecting thoracic curve scoliosis. PMID:23074120

  18. Hydrodynamics from Landau initial conditions

    SciTech Connect

    Sen, Abhisek; Gerhard, Jochen; Torrieri, Giorgio; Read jr, Kenneth F.; Wong, Cheuk-Yin

    2015-01-01

    We investigate ideal hydrodynamic evolution, with Landau initial conditions, both in a semi-analytical 1+1D approach and in a numerical code incorporating event-by-event variation with many events and transverse density inhomogeneities. The object of the calculation is to test how fast would a Landau initial condition transition to a commonly used boost-invariant expansion. We show that the transition to boost-invariant flow occurs too late for realistic setups, with corrections of O (20 - 30%) expected at freezeout for most scenarios. Moreover, the deviation from boost-invariance is correlated with both transverse flow and elliptic flow, with the more highly transversely flowing regions also showing the most violation of boost invariance. Therefore, if longitudinal flow is not fully developed at the early stages of heavy ion collisions, 2+1 dimensional hydrodynamics is inadequate to extract transport coefficients of the quark-gluon plasma. Based on [1, 2

  19. Algorithm refinement for fluctuating hydrodynamics

    SciTech Connect

    Williams, Sarah A.; Bell, John B.; Garcia, Alejandro L.

    2007-07-03

    This paper introduces an adaptive mesh and algorithmrefinement method for fluctuating hydrodynamics. This particle-continuumhybrid simulates the dynamics of a compressible fluid with thermalfluctuations. The particle algorithm is direct simulation Monte Carlo(DSMC), a molecular-level scheme based on the Boltzmann equation. Thecontinuum algorithm is based on the Landau-Lifshitz Navier-Stokes (LLNS)equations, which incorporate thermal fluctuations into macroscopichydrodynamics by using stochastic fluxes. It uses a recently-developedsolver for LLNS, based on third-order Runge-Kutta. We present numericaltests of systems in and out of equilibrium, including time-dependentsystems, and demonstrate dynamic adaptive refinement by the computationof a moving shock wave. Mean system behavior and second moment statisticsof our simulations match theoretical values and benchmarks well. We findthat particular attention should be paid to the spectrum of the flux atthe interface between the particle and continuum methods, specificallyfor the non-hydrodynamic (kinetic) time scales.

  20. Microscopic derivation of discrete hydrodynamics.

    PubMed

    Español, Pep; Anero, Jesús G; Zúñiga, Ignacio

    2009-12-28

    By using the standard theory of coarse graining based on Zwanzig's projection operator, we derive the dynamic equations for discrete hydrodynamic variables. These hydrodynamic variables are defined in terms of the Delaunay triangulation. The resulting microscopically derived equations can be understood, a posteriori, as a discretization on an arbitrary irregular grid of the Navier-Stokes equations. The microscopic derivation provides a set of discrete equations that exactly conserves mass, momentum, and energy and the dissipative part of the dynamics produces strict entropy increase. In addition, the microscopic derivation provides a practical implementation of thermal fluctuations in a way that the fluctuation-dissipation theorem is satisfied exactly. This paper points toward a close connection between coarse-graining procedures from microscopic dynamics and discretization schemes for partial differential equations.

  1. Brain vascular and hydrodynamic physiology

    PubMed Central

    Tasker, Robert C.

    2013-01-01

    Protecting the brain in vulnerable infants undergoing surgery is a central aspect of perioperative care. Understanding the link between blood flow, oxygen delivery and oxygen consumption leads to a more informed approach to bedside care. In some cases, we need to consider how high can we let the partial pressure of carbon dioxide go before we have concerns about risk of increased cerebral blood volume and change in intracranial hydrodynamics? Alternatively, in almost all such cases, we have to address the question of how low can we let the blood pressure drop before we should be concerned about brain perfusion? This review, provides a basic understanding of brain bioenergetics, hemodynamics, hydrodynamics, autoregulation and vascular homeostasis to changes in blood gases that is fundamental to our thinking about bedside care and monitoring. PMID:24331089

  2. Lateral cephalometric radiograph versus lateral nasopharyngeal radiograph for quantitative evaluation of nasopharyngeal airway space

    PubMed Central

    Pereira, Suelen Cristina da Costa; Beltrão, Rejane Targino Soares; Janson, Guilherme; Garib, Daniela Gamba

    2014-01-01

    Objective This study compared lateral radiographs of the nasopharynx (LN) and lateral cephalometric radiographs (LC) used to assess nasopharyngeal airway space in children. Material and Methods One examiner measured the nasopharyngeal space of 15 oral breathing patients aged between 5 and 11 years old by using LN and LC. Both assessments were made twice with a 15-day interval in between. Intergroup comparison was performed with t-tests (P < 0.05). Results Comparison between LN and LC measurements showed no significant differences. Conclusion Lateral cephalometric radiograph is an acceptable method used to assess nasopharyngeal airway space. PMID:25279526

  3. Hydrodynamic Viscosity in Accretion Disks

    NASA Astrophysics Data System (ADS)

    Duschl, Wolfgang J.; Strittmatter, Peter A.; Biermann, Peter L.

    We propose a generalized accretion disk viscosity prescription based on hydrodynamically driven turbulence at the critical effective Reynolds number. This approach is consistent with recent re-analysis by Richard & Zahn (1999) of experimental results on turbulent Couette-Taylor flows. This new β-viscosity formulation applies to both selfgravitating and non-selfgravitating disks and is shown to yield the standard α-disk prescription in the case of shock dissipation limited, non-selfgravitating disks.

  4. Hydrodynamic Simulations of Planetary Rings

    NASA Astrophysics Data System (ADS)

    Miller, Jacob; Stewart, G. R.; Esposito, L. W.

    2013-10-01

    Simulations of rings have traditionally been done using N-body methods, granting insight into the interactions of individual ring particles on varying scales. However, due to the scale of a typical ring system and the sheer number of particles involved, a global N-body simulation is too computationally expensive, unless particle collisions are replaced by stochastic forces (Bromley & Kenyon, 2013). Rings are extraordinarily flat systems and therefore are well-suited to existing geophysical shallow-water hydrodynamics models with well-established non-linear advection methods. By adopting a general relationship between pressure and surface density such as a polytropic equation of state, we can modify the shallow-water formula to treat a thin, compressible, self-gravitating, shearing fluid. Previous hydrodynamic simulations of planetary rings have been restricted to axisymmetric flows and therefore have not treated the response to nonaxisymmetric perturbations by moons (Schmidt & Tscharnuter 1999, Latter & Ogilvie 2010). We seek to expand on existing hydrodynamic methods and, by comparing our work with complementary N-body simulations and Cassini observations, confirm the veracity of our results at small scales before eventually moving to a global domain size. We will use non-Newtonian, dynamically variable viscosity to model the viscous transport caused by unresolved self-gravity wakes. Self-gravity will be added to model the dynamics of large-scale structures, such as density waves and edge waves. Support from NASA Outer Planets and Planetary Geology and Geophysics programs is gratefully acknowledged.

  5. Particle hydrodynamics with tessellation techniques

    NASA Astrophysics Data System (ADS)

    Heß, Steffen; Springel, Volker

    2010-08-01

    Lagrangian smoothed particle hydrodynamics (SPH) is a well-established approach to model fluids in astrophysical problems, thanks to its geometric flexibility and ability to automatically adjust the spatial resolution to the clumping of matter. However, a number of recent studies have emphasized inaccuracies of SPH in the treatment of fluid instabilities. The origin of these numerical problems can be traced back to spurious surface effects across contact discontinuities, and to SPH's inherent prevention of mixing at the particle level. We here investigate a new fluid particle model where the density estimate is carried out with the help of an auxiliary mesh constructed as the Voronoi tessellation of the simulation particles instead of an adaptive smoothing kernel. This Voronoi-based approach improves the ability of the scheme to represent sharp contact discontinuities. We show that this eliminates spurious surface tension effects present in SPH and that play a role in suppressing certain fluid instabilities. We find that the new `Voronoi Particle Hydrodynamics' (VPH) described here produces comparable results to SPH in shocks, and better ones in turbulent regimes of pure hydrodynamical simulations. We also discuss formulations of the artificial viscosity needed in this scheme and how judiciously chosen correction forces can be derived in order to maintain a high degree of particle order and hence a regular Voronoi mesh. This is especially helpful in simulating self-gravitating fluids with existing gravity solvers used for N-body simulations.

  6. Recent progress in anisotropic hydrodynamics

    NASA Astrophysics Data System (ADS)

    Strickland, Michael

    2017-03-01

    The quark-gluon plasma created in a relativistic heavy-ion collisions possesses a sizable pressure anisotropy in the local rest frame at very early times after the initial nuclear impact and this anisotropy only slowly relaxes as the system evolves. In a kinetic theory picture, this translates into the existence of sizable momentum-space anisotropies in the underlying partonic distribution functions, < pL2> ≪ < pT2>. In such cases, it is better to reorganize the hydrodynamical expansion by taking into account momentum-space anisotropies at leading-order in the expansion instead of as a perturbative correction to an isotropic distribution. The resulting anisotropic hydrodynamics framework has been shown to more accurately describe the dynamics of rapidly expanding systems such as the quark-gluon plasma. In this proceedings contribution, I review the basic ideas of anisotropic hydrodynamics, recent progress, and present a few preliminary phenomenological predictions for identified particle spectra and elliptic flow.

  7. Digital radiographic systems detect boiler tube cracks

    SciTech Connect

    Walker, S.

    2008-06-15

    Boiler water wall leaks have been a major cause of steam plant forced outages. But conventional nondestructive evaluation techniques have a poor track record of detecting corrosion fatigue cracking on the inside surface of the cold side of waterwall tubing. EPRI is performing field trials of a prototype direct-digital radiographic system that promises to be a game changer. 8 figs.

  8. Survey of Radiographic Requirements and Techniques.

    ERIC Educational Resources Information Center

    Farman, Allan G.; Shawkat, Abdul H.

    1981-01-01

    A survey of dental schools revealed little standardization of student requirements for dental radiography in the United States. There was a high degree of variability as to what constituted a full radiographic survey, which has implications concerning the maximum limits to patient exposure to radiation. (Author/MLW)

  9. Veterinary nurse to medical diagnostic radiographer.

    PubMed

    Taylor, Nicholas

    2017-08-19

    Nicholas Taylor is senior diagnostic radiographer at the Great Western Hospital, Swindon, having initially qualified as a veterinary nurse. It was a college lecture that initially sparked his interest in radiography - little did he know where it would lead. British Veterinary Association.

  10. Radiographic applications of spatial frequency multiplexing

    NASA Technical Reports Server (NTRS)

    Macovski, A.

    1981-01-01

    The application of spacial frequency encoding techniques which allow different regions of the X-ray spectrum to be encoded on conventional radiographs was studied. Clinical considerations were reviewed, as were experimental studies involving the encoding and decoding of X-ray images at different energies and the subsequent processing of the data to produce images of specific materials in the body.

  11. TECHNICAL TRAINING FOR INDUSTRIAL RADIOGRAPHERS. FINAL REPORT.

    ERIC Educational Resources Information Center

    BEARDEN, H.D.

    TO OFFSET THE PROBLEM OF A SHORTAGE OF QUALIFIED TECHNICIANS TO SERVE AS RADIOGRAPHERS IN INDUSTRY, 19 STUDENTS WERE TRAINED IN TWO CLASSES, THE FIRST CONSISTING OF 19, AND THE SECOND OF EIGHTEEN 30-HOUR WEEKS. ORGANIZED FORMAL OR LECTURE-TYPE INSTRUCTION WAS PRESENTED IN SOME SUBJECT AREAS, BUT THE MAJOR EMPHASIS WAS ON LABORATORY EXPERIENCES…

  12. Identifying murder victims with endodontic radiographs

    PubMed Central

    Silva, Rhonan Ferreira; Franco, Ademir; Mendes, Solon Diego Santos Carvalho; Picoli, Fernando Fortes; Nunes, Fernando Gomes; Estrela, Carlos

    2016-01-01

    Endodontics is a special branch of dentistry constantly guided by imaging examinations. From a forensic scope, endodontics plays a valuable role providing solid antemortem (AM) radiographic evidence for comparison with postmortem findings in human identifications. This study illustrates the interface between endodontics and forensic odontology describing three cases of human identification based on radiographic endodontic records. From 2009 to 2012, three unknown male victims of murder were examined in a local Brazilian medico-legal institute to retrieve identity and potential cause of death. Specifically, when asked for AM data, a relative of the three victims provided periapical radiographs of endodontic treatments. Based on that, forensic dentists reproduced the same imaging acquisition techniques obtaining similar periapical radiographs, enabling a comparative dental identification. All the victims were positively identified based on patterns of dental morphology and treatment intervention. This study draws the attention of general and forensic dentists highlight the importance of properly recording dental treatments and searching for evidence in AM endodontic data, respectively. PMID:28123272

  13. Survey of Radiographic Requirements and Techniques.

    ERIC Educational Resources Information Center

    Farman, Allan G.; Shawkat, Abdul H.

    1981-01-01

    A survey of dental schools revealed little standardization of student requirements for dental radiography in the United States. There was a high degree of variability as to what constituted a full radiographic survey, which has implications concerning the maximum limits to patient exposure to radiation. (Author/MLW)

  14. Identifying murder victims with endodontic radiographs.

    PubMed

    Silva, Rhonan Ferreira; Franco, Ademir; Mendes, Solon Diego Santos Carvalho; Picoli, Fernando Fortes; Nunes, Fernando Gomes; Estrela, Carlos

    2016-01-01

    Endodontics is a special branch of dentistry constantly guided by imaging examinations. From a forensic scope, endodontics plays a valuable role providing solid antemortem (AM) radiographic evidence for comparison with postmortem findings in human identifications. This study illustrates the interface between endodontics and forensic odontology describing three cases of human identification based on radiographic endodontic records. From 2009 to 2012, three unknown male victims of murder were examined in a local Brazilian medico-legal institute to retrieve identity and potential cause of death. Specifically, when asked for AM data, a relative of the three victims provided periapical radiographs of endodontic treatments. Based on that, forensic dentists reproduced the same imaging acquisition techniques obtaining similar periapical radiographs, enabling a comparative dental identification. All the victims were positively identified based on patterns of dental morphology and treatment intervention. This study draws the attention of general and forensic dentists highlight the importance of properly recording dental treatments and searching for evidence in AM endodontic data, respectively.

  15. Panoramic radiographic demonstration of bilateral tonsilloliths.

    PubMed

    Guevara, Carlo; Mandel, Louis

    2011-04-01

    Calcifications can develop within the crypts of the palatine tonsil. During routine dental panoramic radiography, these tonsillar calcifications, or tonsilloliths, may be visualized superimposed upon the mandibular ramus. Their anatomic location and radiographic appearance are such that confusion with parotid sialolithiasis may occur. This report defines the symptomatology and differential diagnosis of these tonsilloliths.

  16. Detecting objects in radiographs for homeland security

    NASA Astrophysics Data System (ADS)

    Prasad, Lakshman; Snyder, Hans

    2005-05-01

    We present a general scheme for segmenting a radiographic image into polygons that correspond to visual features. This decomposition provides a vectorized representation that is a high-level description of the image. The polygons correspond to objects or object parts present in the image. This characterization of radiographs allows the direct application of several shape recognition algorithms to identify objects. In this paper we describe the use of constrained Delaunay triangulations as a uniform foundational tool to achieve multiple visual tasks, namely image segmentation, shape decomposition, and parts-based shape matching. Shape decomposition yields parts that serve as tokens representing local shape characteristics. Parts-based shape matching enables the recognition of objects in the presence of occlusions, which commonly occur in radiographs. The polygonal representation of image features affords the efficient design and application of sophisticated geometric filtering methods to detect large-scale structural properties of objects in images. Finally, the representation of radiographs via polygons results in significant reduction of image file sizes and permits the scalable graphical representation of images, along with annotations of detected objects, in the SVG (scalable vector graphics) format that is proposed by the world wide web consortium (W3C). This is a textual representation that can be compressed and encrypted for efficient and secure transmission of information over wireless channels and on the Internet. In particular, our methods described here provide an algorithmic framework for developing image analysis tools for screening cargo at ports of entry for homeland security.

  17. 21 CFR 1020.31 - Radiographic equipment.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... (PBL). The requirements of this paragraph shall apply to radiographic systems which contain PBL. (1) Field size. When a PBL system is provided, it shall prevent x-ray production when: (i) Either the length.... (iii) The beam limiting device is at an SID for which PBL is not designed for sizing. (2) Conditions...

  18. A Tutorial for Performing a Radiographic Examination

    DTIC Science & Technology

    2017-03-01

    an in-depth understanding and illustration of the content and tangible functions that are necessary to complete an entire nondestructive test . 15...SUBJECT TERMS Radiography Munitions X-ray Nondestructive testing (NDT) Radiographic testing (RT) 16. SECURITY CLASSIFICATION...unlimited. UNCLASSIFIED 1 INTRODUCTION: PERSONNEL QUALIFICATIONS Developed by the American Society of Testing and Materials (ASTM), the

  19. Age estimation using intraoral periapical radiographs

    PubMed Central

    Rajpal, Pooja S.; Krishnamurthy, Vasavi; Pagare, Sandeep S.; Sachdev, Geeta D.

    2016-01-01

    Context: Changes in the size of dental pulp caused by the apposition of secondary dentin and occlusal wear are morphometric parameters for estimating age. Aim: To estimate the accuracy of age evaluation by Kvaal's method and the effect of occlusal wear on age using digital intraoral periapical radiographs in a subset of the Indian population. Materials and Methods: A total of 300 teeth were radiographically evaluated using intraoral periapical digital radiographs from 50 adult patients. A few modifications were made in the design of the study compared to the original Kvaal's method. The radiographs of three teeth from each jaw were taken and morphometric measurements in ratios were analyzed, which included the pulp length to tooth length (X1), pulp length to root length (X2), pulp width to root widths at three defined levels (X3), and tooth length to root length (X4). Statistical Analysis: The Pearson product-moment correlation coefficient (PCC) between age and the morphological variables showed that among them X1, X2, and X3 were statistically significant but not the tooth root length ratio (X4). Conclusions: The ratios X1, X2, and X3 were good indicators of age and hence a multiple linear regression model for age estimation was derived using these three variables. However, it was found that X4 was not a good indicator of age estimation in said population. PMID:27051226

  20. Pulp size in molars: underestimation on radiographs.

    PubMed

    Chandler, N P; Ford, T R Pitt; Monteith, B D

    2004-08-01

    The aim was to determine whether radiographs provide a clinically useful indication of pulp size in diseased/restored human first molar teeth, and to investigate accessibility of pulp tissue for diagnostic testing using laser Doppler flowmetry (LDF). Extracted teeth of known age were collected. Restorative materials were removed and teeth with evidence of pulp exposures excluded. Fifty-six teeth were radiographed from buccal and mesial aspects, and then their crowns were sectioned axiobuccolingually and photographed. Images were digitally scanned and measurements made of the total pulp area (above a line across the most superior part of the pulpal floor) and the pulp area in the clinical crown (superior to a line between the amelocemental junctions). The pulp width at the cervix and the highest point of the pulp were also recorded. Data were analysed using Pearson correlations. Pulp areas within the clinical crowns were significantly larger than indicated by radiographs, by 23% in the case of the clinically attainable buccal view (P < 0.05). Pulps may be more accessible to flowmeter testing than they appear. Absence of pulp tissues in the crown was recorded in equal numbers of teeth on radiographs and sections, but with agreement for only one tooth. Sixteen per cent of the teeth had no pulp area in the clinical crown when sectioned, but might still be suitable for testing using LDF.

  1. Radiographic evaluation and assessment of paragangliomas.

    PubMed

    Lustrin, E S; Palestro, C; Vaheesan, K

    2001-10-01

    Radiographic imaging plays an important role in the diagnosis and treatment of paragangliomas. Diagnosis and treatment should be performed as a team effort, with all the involved disciplines working together to provide the best possible individualized work-up and treatment plan for the patient.

  2. Radiographic Differentiation of Advanced Fibrocystic Lung Diseases.

    PubMed

    Akira, Masanori

    2017-03-01

    The concept of end-stage lung disease suggests a final common pathway for most diffuse parenchymal lung diseases. In accordance with this concept, end-stage disease is characterized radiographically and pathologically by the presence of extensive honeycombing. However, sequential computed tomographic (CT) scans obtained from patients with chronic diffuse lung disease evolve over time to show various advanced lung disease patterns other than honeycombing. In addition, several radiographically distinct honeycomb patterns, including microcystic, macrocystic, mixed, and combined emphysema and honeycombing, differentiate one advanced lung disease from another. For example, usual interstitial pneumonia (IP) usually shows mixed microcystic and macrocystic honeycombing. In contrast, CT images of long-standing fibrotic nonspecific IP typically show only small, scattered foci of honeycombing; instead, most enlarged airspaces observed in the advanced stage of this disease represent dilatation of bronchioles. In desquamative IP and pulmonary Langerhans cell histiocytosis, focal opacities typically evolve into emphysema-like lesions seen on CT imaging. In combined pulmonary fibrosis and emphysema and sarcoidosis, the cysts tend to be larger than those observed in usual IP. Sequential CT scans in other chronic, diffuse lung diseases also show various distinctive changes. This article highlights radiographic patterns of lung destruction that belie a single common pathway to end-stage lung disease. Recognition of distinct radiographic patterns of lung destruction can help differentiate diffuse parenchymal lung diseases, even in advanced stages of disease evolution.

  3. Radiographic morphology of the cranial portion of the cervical vertebral column in Cavalier King Charles Spaniels and its relationship to syringomyelia.

    PubMed

    Stalin, Catherine E; Rusbridge, Clare; Granger, Nicolas; Jeffery, Nick D

    2008-01-01

    To compare radiographic morphology of the atlantoaxial region between Cavalier King Charles Spaniels (CKCSs) and dogs of other breeds and determine whether there was an association between radiographic morphology of the atlantoaxial region and syringomyelia in CKCSs. 65 CKCSs and 72 dogs of other breeds. The amount that the spinous process of the axis overlapped the dorsal arch of the atlas, the relative size of the spinous process of the axis, and the amount of widening of the atlantoaxial joint that occurred when the neck was moved from a neutral to a flexed position were measured on lateral radiographic projections of the atlantoaxial region. Magnetic resonance images were reviewed to identify CKCSs with syringomyelia. The amount of overlap of the atlas and axis and the relative size of the spinous process of the axis were significantly smaller in CKCSs than in dogs of other breeds. However, the amount of widening of the atlantoaxial joint that occurred when the neck was moved from a neutral to a flexed position was not significantly different between groups, and no association was detected between syringomyelia and excessive atlantoaxial joint space widening or between syringomyelia and an excessively small axial spinous process. Results suggested that radiographic morphology of the atlantoaxial region in CKCSs differs from morphology of that region in dogs of other breeds, but that these differences do not account for why some CKCSs develop syringomyelia and others do not.

  4. Ergonomic strategies to improve radiographers' posture during mammography activities.

    PubMed

    Cernean, Nicolai; Serranheira, Florentino; Gonçalves, Pedro; Sá Dos Reis, Cláudia

    2017-08-01

    To identify alternatives for radiographers' postures while performing mammography that can contribute to reduce the risk of work-related musculoskeletal disorders (WRMSDs). Radiographers' postures to positioning craniocaudal (CC) and mediolateral oblique (MLO) views were simulated without any intervention for three scenarios: radiographer/patient with similar statures, radiographer smaller than patient and radiographer taller than patient. Actions were taken to modify the postures: seated radiographer; patient on a step; seated patient; radiographer on a step. All the postures were analysed using kinovea 0.8.15 software and the angles were measured twice and classified according to European standard EN1005-4: 2005. The non-acceptable angles were measured mainly during MLO positioning when radiographer was taller than the patient: 139° and 120° for arm-flexion and abduction, 72° for trunk and -24° for head/neck-flexion. The introduction of alternative postures (radiographer seated), allowed improvements in posture (60° and 99° for arm flexion and abduction, 14° for trunk and 0° for head/neck flexion), being classified as acceptable. The alternative postures simulated have the potential to reduce the risk of developing WRMSDs when radiographers and patients have different statures. • Radiographers' postures in mammography can contribute to work-related musculoskeletal disorders • Non-acceptable posture was identified for MLO breast positioning (radiographer taller than patient) • Adapting posture to patient biotype reduces the WRMSD risk for radiographers.

  5. Three-dimensional Numerical Analysis on Blade Response of Vertical Axis Tidal Current Turbine Under Operational Condition

    SciTech Connect

    Li, Ye; Karri, Naveen K.; Wang, Qi

    2014-04-30

    Tidal power as a large-scale renewable source of energy has been receiving significant attention recently because of its advantages over the wind and other renewal energy sources. The technology used to harvest energy from tidal current is called a tidal current turbine. Though some of the principles of wind turbine design are applicable to tidal current turbines, the design of latter ones need additional considerations like cavitation damage, corrosion etc. for the long-term reliability of such turbines. Depending up on the orientation of axis, tidal current turbines can be classified as vertical axis turbines or horizontal axis turbines. Existing studies on the vertical axis tidal current turbine focus more on the hydrodynamic aspects of the turbine rather than the structural aspects. This paper summarizes our recent efforts to study the integrated hydrodynamic and structural aspects of the vertical axis tidal current turbines. After reviewing existing methods in modeling tidal current turbines, we developed a hybrid approach that combines discrete vortex method -finite element method that can simulate the integrated hydrodynamic and structural response of a vertical axis turbine. This hybrid method was initially employed to analyze a typical three-blade vertical axis turbine. The power coefficient was used to evaluate the hydrodynamic performance, and critical deflection was considered to evaluate the structural reliability. A sensitivity analysis was also conducted with various turbine height-to-radius ratios. The results indicate that both the power output and failure probability increase with the turbine height, suggesting a necessity for optimal design. An attempt to optimize a 3-blade vertical axis turbine design with hybrid method yielded a ratio of turbine height to radius (H/R) about 3.0 for reliable maximum power output.

  6. Radiographic analysis of ameloblastoma: a retrospective study.

    PubMed

    More, Chandramani; Tailor, Mansi; Patel, Hetul J; Asrani, Mukesh; Thakkar, Krushna; Adalja, Chhaya

    2012-01-01

    Ameloblastoma is benign odontogenic tumor, usually affecting the posterior region of mandible. It is seen in the third to fifth decades of life. Radiographically the lesion is variable in appearance and may be unilocular or multilocular, with well-defined cortical borders in the mandible and ill-defined margins in the maxilla. To analyze cases of ameloblastoma, with emphasis on the radiographic findings. We also review the current literature briefly and discuss the clinical and radiographic findings. The present hospital-based retrospective study was conducted by reviewing the clinical and radiographic records of ameloblastoma cases from 2009 to 2011, available in the archives of the department. The data of a total of 14 patients were analyzed. We observed that the patients affected with ameloblastoma were in the age-group of 19-68 years. The male: female ratio was 1.3:1. The mandible (78.57%) was more commonly affected than the maxilla (14.28%). Six patients (42.86%) had unilateral involvement and eight cases (57.14%) had bilateral involvement. The multilocular and unilocular types of ameloblastoma were noted in 12 (85.72%) and 2 cases (14.28%), respectively. The soap-bubble (50.00%), spider-web (21.43%), and honeycomb (14.28%) appearances were seen in the multilocular variety. Root resorption of variable degree was distinctly observed in 11 cases (78.57%). Radiographs are an important aid for the diagnosis of oral lesions of various types, especially those that involve bone. It is important for the practicing clinicians to know the salient features of ameloblastoma which are peculiar to the local population.

  7. Entropy-limited hydrodynamics: a novel approach to relativistic hydrodynamics

    NASA Astrophysics Data System (ADS)

    Guercilena, Federico; Radice, David; Rezzolla, Luciano

    2017-07-01

    We present entropy-limited hydrodynamics (ELH): a new approach for the computation of numerical fluxes arising in the discretization of hyperbolic equations in conservation form. ELH is based on the hybridisation of an unfiltered high-order scheme with the first-order Lax-Friedrichs method. The activation of the low-order part of the scheme is driven by a measure of the locally generated entropy inspired by the artificial-viscosity method proposed by Guermond et al. (J. Comput. Phys. 230(11):4248-4267, 2011, doi: 10.1016/j.jcp.2010.11.043). Here, we present ELH in the context of high-order finite-differencing methods and of the equations of general-relativistic hydrodynamics. We study the performance of ELH in a series of classical astrophysical tests in general relativity involving isolated, rotating and nonrotating neutron stars, and including a case of gravitational collapse to black hole. We present a detailed comparison of ELH with the fifth-order monotonicity preserving method MP5 (Suresh and Huynh in J. Comput. Phys. 136(1):83-99, 1997, doi: 10.1006/jcph.1997.5745), one of the most common high-order schemes currently employed in numerical-relativity simulations. We find that ELH achieves comparable and, in many of the cases studied here, better accuracy than more traditional methods at a fraction of the computational cost (up to {˜}50% speedup). Given its accuracy and its simplicity of implementation, ELH is a promising framework for the development of new special- and general-relativistic hydrodynamics codes well adapted for massively parallel supercomputers.

  8. Accuracy of radiographs in assessment of displacement in lateral humeral condyle fractures.

    PubMed

    Knutsen, Ashleen; Avoian, Tigran; Borkowski, Sean L; Ebramzadeh, Edward; Zionts, Lewis E; Sangiorgio, Sophia N

    2014-02-01

    Determining the magnitude of displacement in pediatric lateral humeral condyle fractures can be difficult. The purpose of this study was to (1) assess the effect of forearm rotation on true fracture displacement using a cadaver model and to (2) determine the accuracy of radiographic measurements of the fracture gap. A non-displaced fracture was created in three human cadaveric arms. The specimens were mounted on a custom apparatus allowing forearm rotation with the humerus fixed. First, the effect of pure rotation on fracture displacement was simulated by rotating the forearm from supination to pronation about the central axis of the forearm, to isolate the effects of muscle pull. Then, the clinical condition of obtaining a lateral oblique radiograph was simulated by rotating the forearm about the medial aspect of the forearm. Fracture displacements were measured using a motion-capture system (true-displacement) and clinical radiographs (apparent-displacement). During pure rotation of the forearm, there were no significant differences in fracture displacement between supination and pronation, with changes in displacement of <1.0 mm. During rotation about the medial aspect of the forearm, there was a significant difference in true displacements between supination and pronation at the posterior edge (p < 0.05). Overall, true fracture displacement measurements were larger than apparent radiographic displacement measurements, with differences from 1.6 to 6.0 mm, suggesting that the current clinical methods may not be sensitive enough to detect a displacement of 2.0 mm, especially when positioning the upper extremity for an internal oblique lateral radiograph.

  9. 10 CFR Appendix A to Part 34 - Radiographer Certification

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... INDUSTRIAL RADIOGRAPHIC OPERATIONS Pt. 34, App. A Appendix A to Part 34—Radiographer Certification I... Agreement State requirements; 2. Written in a multiple-choice format; 3. Have test items drawn from...

  10. 21 CFR 892.1850 - Radiographic film cassette.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ...) Identification. A radiographic film cassette is a device intended for use during diagnostic x-ray procedures to hold a radiographic film in close contact with an x-ray intensifying screen and to provide a light...

  11. 42 CFR 37.41 - Chest radiograph specifications-film.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... specifications—film. (a) Miners must be disrobed from the waist up at the time the radiograph is given. The... which is at least 100 and does not exceed 300, that produces radiographs with spatial resolution...

  12. 42 CFR 37.41 - Chest radiograph specifications-film.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) Miners must be disrobed from the waist up at the time the radiograph is given. The facility must provide... which is at least 100 and does not exceed 300, that produces radiographs with spatial resolution...

  13. Radiographic landmark for humeral head rotation: a new radiographic landmark for humeral fracture fixation.

    PubMed

    Tan, Jun; Lee, Hyun-Joo; Aminata, Iman; Chun, Jae-Myeung; Kekatpure, Aashay L; Jeon, In-Ho

    2015-04-01

    There is no definite radiographic landmark in plain radiographs for proximal humeral rotation, which is an important parameter for avoiding rotational malalignment during fracture fixation. Here, we used radiographic images of cadaveric humeri to determine whether the landmark of the crest of lesser tuberosity (CoLT) in plain radiographs could be used to determine humeral rotation. Twenty adult cadaveric humeri were collected and seven consecutive radiographic anteroposterior views (45°, 30°, 15° internal rotation; neutral rotation; and 15°, 30°, 45° external rotation) were obtained for each specimen. The proportional distance (PD) of the CoLT landmark relative to the humeral head was measured and analysed. The mean PDs of the CoLT landmark were 10.2%, 17.9%, 25.6%, 35.9%, 53.4%, and 62.9% of the diameter of the humeral head, corresponding to 45°, 30°, and 15° external rotation, neutral rotation, and 15° and 30° internal rotation, respectively. We found significant differences in the mean PDs with humeral rotation. The projection of the CoLT in plain radiographs can be used as an important landmark to assess humeral head rotation and will be a useful landmark for rotational control of fracture fixation. Copyright © 2014 Elsevier Ltd. All rights reserved.

  14. New radiographic image processing tested on the simple and double-flux platform at OMEGA

    NASA Astrophysics Data System (ADS)

    Poujade, Olivier; Ferri, Michel; Geoffray, Isabelle

    2017-10-01

    Ablation fronts and shocks are two radiative/hydrodynamic features ubiquitous in inertial confinement fusion (ICF). A specially designed shock-tube experiment was tested on the OMEGA laser facility to observe that these two features evolve at once and to assess thermodynamical and radiative properties. It is a basic science experiment aimed at improving our understanding of shocked and ablated matter which is critical to ICF design. At all time, these two moving "interfaces" separate the tube into three distinct zones where matter is ablated, shocked, or unshocked. The simple-flux or double-flux experiments, respectively, one or two halfraum-plus-tube, have been thought up to observe and image these zones using x-ray and visible image diagnostic. The possibility of observing all three regions at once was instrumental in our new radiographic image processing used to remove the backlighter background otherwise detrimental to quantitative measurements. By so doing, after processing the radiographic images of the 15 shots accumulated during the 2013 and 2015 campaigns, a quantitative comparison between experiments and our radiative hydrocode simulations was made possible. One point of the principal Hugoniot of the aerogel used as a light material in the shock-tube was inferred from that comparison. Most surprisingly, rapid variations of relative-transmission in the ablated region were observed during radiographic irradiations while it remained constant in the shocked region. This effect might be attributed to the spectral distribution variability of the backlighter during the radiographic pulse. Numerically, that distribution is strongly dependent upon NLTE models and it could potentially be used as a means to discriminate among them.

  15. The radiographic presentation of osteomyelitis in the foot.

    PubMed

    Christman, R A

    1990-07-01

    Numerous authors have described the radiographic findings associated with osteomyelitis. Knowledge of these findings and their presentation radiographically may make diagnosis of this pathology quite simple. The challenge comes not in diagnosing osteomyelitis based on gross radiographic evidence; by this time, the disease has significantly progressed. The challenge is to be able to recognize early, subtle changes, and, in conjunction with clinical findings, to diagnose and treat the disease before classic radiographic evidence is demonstrated.

  16. An Innovative Method of Assessing the Mechanical Axis Deviation in the Lower Limb in Standing Position.

    PubMed

    Kamath, Jagannath; Danda, Raja Shekar; Jayasheelan, Nikil; Singh, Rohit

    2016-06-01

    Various methods of measuring mechanical axis deviation of lower limb have been described including radiographic and CT scanogram, intraoperative fluoroscopy with the use of an electrocautery cord. These methods determine the mechanical axis in a supine, non-weight bearing position. Although long cassette standing radiographic view is used for the purpose but is not available at most centres. A dynamic method of determining the mechanical axis in a weight bearing position was devised in this study. The aim of the study was to describe a simpler and newer method in quantifying the mechanical axis deviation in places where full length cassettes for standing X rays are not available. A pilot study was conducted on 15 patients. The deviation from the mechanical axis was measured using a manually operated, hydraulic mechanism based, elevating scissor lift table. Patient was asked to stand erect over the elevating lift table with both patellae facing forward and C-arm image intensifier was positioned horizontally. Radiological markers were tied to a radio-opaque thread and placed at the centre of head of the femur and another at the centre of the tibio-talar joint. C-arm views of the hip, ankle and knee joint were taken to confirm the correct position of the marker by varying the height of the lift table. The mechanical axis deviation values were recorded by measuring distance between the centre of the knee and radio-opaque thread in cm. This was measured in each case both clinically and from the image on the monitor. The two values were found to be statistically same. Pain was measured on VAS. Mechanical axis deviation values and VAS score were found to be positively significantly correlated. This technique is dynamic, unique and accurate as compared to other methods for assessing mechanical axis deviation in a weight bearing position.

  17. Femoral osteochondritis of the knee: prognostic value of the mechanical axis.

    PubMed

    Gonzalez-Herranz, P; Rodriguez, M L; de la Fuente, C

    2017-01-01

    Femoral osteochondritis dissecans (OCD) is a disorder of unknown aetiology and variable prognosis that causes knee pain. In this paper, the authors study the impact of lower limb malalignment on the development and prognosis of OCD. After anteroposterior (AP) and lateral radiograph and MRI of the knee, 53 cases of OCD were diagnosed. All patients were studied by standing full-length AP radiograph of the lower extremities in order to analyse the relationship between the femorotibial and mechanical axis and the location and stability of the osteochondritis. The OCD lesion was located in the medial condyle (zone 2) in 75.5% of cases (40 cases). The lateral condyle was affected in 24.5% of cases (zone 4 in nine cases and zone 5 in four cases). The femorotibial angle (anatomical axis) was normally aligned in 68% of cases. A valgus deformity was observed in 9.5% of cases and a varus deformity in 22.5%. The mechanical axis of the limb appeared normal in only 32% of cases, with medial deviation in 53%, and lateral deviation in 15% of cases. When the OCD lesion was located in the medial condyle (40 cases), the mechanical axis also crossed the knee through the medial zone in 28 cases. When the OCD lesion was located in the lateral condyle (13 cases), the mechanical axis crossed the knee through zones 1 or 2 in four cases. In stable OCD, the mechanical axis and location of the lesion coincided in 19 of 36 cases (52%), compared with 16 of 17 cases (94%) in unstable OCD. There is a high correlation between OCD location and lower limb mechanical axis deviation. The convergence of the mechanical axis with the location of the OCD lesion may be considered an associated factor in fragment instability. This convergence is more common in unstable OCD.

  18. 21 CFR 892.1640 - Radiographic film marking system.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic film marking system. 892.1640 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1640 Radiographic film marking system. (a) Identification. A radiographic film marking system is a device intended for medical purposes...

  19. 21 CFR 892.1850 - Radiographic film cassette.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic film cassette. 892.1850 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1850 Radiographic film cassette. (a) Identification. A radiographic film cassette is a device intended for use during diagnostic x-ray procedures...

  20. 21 CFR 892.1860 - Radiographic film/cassette changer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic film/cassette changer. 892.1860... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1860 Radiographic film/cassette changer. (a) Identification. A radiographic film/cassette changer is a device intended to be used during...

  1. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  2. 21 CFR 892.1860 - Radiographic film/cassette changer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic film/cassette changer. 892.1860... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1860 Radiographic film/cassette changer. (a) Identification. A radiographic film/cassette changer is a device intended to be used during...

  3. 21 CFR 892.1860 - Radiographic film/cassette changer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic film/cassette changer. 892.1860... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1860 Radiographic film/cassette changer. (a) Identification. A radiographic film/cassette changer is a device intended to be used during...

  4. 21 CFR 892.1640 - Radiographic film marking system.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic film marking system. 892.1640 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1640 Radiographic film marking system. (a) Identification. A radiographic film marking system is a device intended for medical purposes...

  5. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  6. 21 CFR 892.1900 - Automatic radiographic film processor.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Automatic radiographic film processor. 892.1900... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1900 Automatic radiographic film processor. (a) Identification. An automatic radiographic film processor is a device intended to be used...

  7. 21 CFR 892.1850 - Radiographic film cassette.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic film cassette. 892.1850 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1850 Radiographic film cassette. (a) Identification. A radiographic film cassette is a device intended for use during diagnostic x-ray procedures...

  8. 21 CFR 892.1860 - Radiographic film/cassette changer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic film/cassette changer. 892.1860... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1860 Radiographic film/cassette changer. (a) Identification. A radiographic film/cassette changer is a device intended to be used during...

  9. 21 CFR 892.1640 - Radiographic film marking system.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic film marking system. 892.1640 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1640 Radiographic film marking system. (a) Identification. A radiographic film marking system is a device intended for medical purposes...

  10. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  11. 21 CFR 892.1900 - Automatic radiographic film processor.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Automatic radiographic film processor. 892.1900... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1900 Automatic radiographic film processor. (a) Identification. An automatic radiographic film processor is a device intended to be used...

  12. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  13. 21 CFR 892.1850 - Radiographic film cassette.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic film cassette. 892.1850 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1850 Radiographic film cassette. (a) Identification. A radiographic film cassette is a device intended for use during diagnostic x-ray procedures...

  14. 21 CFR 892.1900 - Automatic radiographic film processor.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Automatic radiographic film processor. 892.1900... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1900 Automatic radiographic film processor. (a) Identification. An automatic radiographic film processor is a device intended to be used...

  15. 21 CFR 892.1900 - Automatic radiographic film processor.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Automatic radiographic film processor. 892.1900... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1900 Automatic radiographic film processor. (a) Identification. An automatic radiographic film processor is a device intended to be used...

  16. 21 CFR 892.1860 - Radiographic film/cassette changer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic film/cassette changer. 892.1860... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1860 Radiographic film/cassette changer. (a) Identification. A radiographic film/cassette changer is a device intended to be used during...

  17. 21 CFR 892.1890 - Radiographic film illuminator.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic film illuminator. 892.1890 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1890 Radiographic film illuminator. (a) Identification. A radiographic film illuminator is a device containing a visible light source covered with...

  18. 21 CFR 892.1850 - Radiographic film cassette.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic film cassette. 892.1850 Section 892...) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1850 Radiographic film cassette. (a) Identification. A radiographic film cassette is a device intended for use during diagnostic x-ray procedures...

  19. 21 CFR 892.1900 - Automatic radiographic film processor.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Automatic radiographic film processor. 892.1900... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1900 Automatic radiographic film processor. (a) Identification. An automatic radiographic film processor is a device intended to be used...

  20. 21 CFR 892.1640 - Radiographic film marking system.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic film marking system. 892.1640 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1640 Radiographic film marking system. (a) Identification. A radiographic film marking system is a device intended for medical purposes...

  1. 21 CFR 892.1640 - Radiographic film marking system.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic film marking system. 892.1640 Section... (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1640 Radiographic film marking system. (a) Identification. A radiographic film marking system is a device intended for medical purposes...

  2. What is the real angle of deviation of metacarpal neck fractures on oblique views? A radiographic study☆

    PubMed Central

    de Góes Ribeiro, Arthur; Gonçalez, Daniel Hidalgo; Filho, João Manoel Fonseca; da Fonseca, Guilherme Marques; Costa, Antonio Carlos; Chakkour, Ivan

    2016-01-01

    Objective The aim of this study was to establish an indirect, easy-to-use, predictable and safe means of obtaining the true degree of displacement of fractures of the neck of the fifth metacarpal bone, through oblique radiographic views. Methods An anatomical specimen from the fifth human metacarpal was dissected and subjected to ostectomy in the neck region. A 1-mm Kirschner wire was fixed to the base of the fifth metacarpal bone, perpendicular to the longitudinal axis of the bone and parallel to the ground. Another six Kirschner wires of the same diameter were bent over and attached to the ostectomized bone to simulate fracture displacement. Axial rotation of the metacarpus was used to create oblique radiographic views. Radiographic images were generated with different angles and at several degrees of rotation of the bone. Results We deduced a mathematical formula that showed the true displacement of fractures of the neck of the fifth metacarpal bone by means of oblique radiographs. Conclusions Oblique radiographs at 30̊ of supination provided the best view of the bone and least variation from the real value of the displacement of fractures of the fifth metacarpal bone. The mathematical formula deduced was concordant with the experimental model used. PMID:27069882

  3. Paraboloids and Vortices in Hydrodynamics

    ERIC Educational Resources Information Center

    Goodman, John M.

    1969-01-01

    Describes an apparatus designed to demonstrate vortical flow of a fluid. The apparatus consists of a transparent acrylic cylinder, with a drain hole, and mounted so that it can be rotated about its axis at speeds up to 1000 rpm. Experimental observations with water as the fluid under study are reported. (LC)

  4. HEMP. Hydrodynamic Elastic Magneto Plastic

    SciTech Connect

    Wilkins, M.L.; Levatin, J.A.

    1985-02-01

    The HEMP code solves the conservation equations of two-dimensional elastic-plastic flow, in plane x-y coordinates or in cylindrical symmetry around the x-axis. Provisions for calculation of fixed boundaries, free surfaces, pistons, and boundary slide planes have been included, along with other special conditions.

  5. Paraboloids and Vortices in Hydrodynamics

    ERIC Educational Resources Information Center

    Goodman, John M.

    1969-01-01

    Describes an apparatus designed to demonstrate vortical flow of a fluid. The apparatus consists of a transparent acrylic cylinder, with a drain hole, and mounted so that it can be rotated about its axis at speeds up to 1000 rpm. Experimental observations with water as the fluid under study are reported. (LC)

  6. Galaxy clusters as hydrodynamics laboratories

    NASA Astrophysics Data System (ADS)

    Roediger, Elke; Sheardown, Alexander; Fish, Thomas; ZuHone, John; Hunt, Matthew; Su, Yuanyuan; Kraft, Ralph P.; Nulsen, Paul; Forman, William R.; Churazov, Eugene; Randall, Scott W.; Jones, Christine; Machacek, Marie E.

    2017-08-01

    The intra-cluster medium (ICM) of galaxy clusters shows a wealth of hydrodynamical features that trace the growth of clusters via the infall of galaxies or smaller subclusters. Such hydrodynamical features include the wakes of the infalling objects as well as the interfaces between the host cluster’s ICM and the atmosphere of the infalling object. Furthermore, the cluster dynamics can be traced by merger shocks, bow shocks, and sloshing motions of the ICM.The characteristics of these dynamical features, e.g., the direction, length, brightness, and temperature of the galaxies' or subclusters' gas tails varies significantly between different objects. This could be due to either dynamical conditions or ICM transport coefficients such as viscosity and thermal conductivity. For example, the cool long gas tails of of some infalling galaxies and groups have been attributed to a substantial ICM viscosity suppressing mixing of the stripped galaxy or group gas with the hotter ambient ICM.Using hydrodynamical simulations of minor mergers we show, however, that these features can be explained naturally by the dynamical conditions of each particular galaxy or group infall. Specifically, we identify observable features to distinguish the first and second infall of a galaxy or group into its host cluster as well as characteristics during apocentre passage. Comparing our simulations with observations, we can explain several puzzling observations such as the long and cold tail of M86 in Virgo and the very long and tangentially oriented tail of the group LEDA 87445 in Hydra A.Using our simulations, we also assess the validity of the stagnation pressure method that is widely used to determine an infalling galaxy's velocity. We show that near pericentre passage the method gives reasonable results, but near apocentre it is not easily applicable.

  7. Forced wetting and hydrodynamic assist

    NASA Astrophysics Data System (ADS)

    Blake, Terence D.; Fernandez-Toledano, Juan-Carlos; Doyen, Guillaume; De Coninck, Joël

    2015-11-01

    Wetting is a prerequisite for coating a uniform layer of liquid onto a solid. Wetting failure and air entrainment set the ultimate limit to coating speed. It is well known in the coating art that this limit can be postponed by manipulating the coating flow to generate what has been termed "hydrodynamic assist," but the underlying mechanism is unclear. Experiments have shown that the conditions that postpone air entrainment also reduce the apparent dynamic contact angle, suggesting a direct link, but how the flow might affect the contact angle remains to be established. Here, we use molecular dynamics to compare the outcome of steady forced wetting with previous results for the spontaneous spreading of liquid drops and apply the molecular-kinetic theory of dynamic wetting to rationalize our findings and place them on a quantitative footing. The forced wetting simulations reveal significant slip at the solid-liquid interface and details of the flow immediately adjacent to the moving contact line. Our results confirm that the local, microscopic contact angle is dependent not simply only on the velocity of wetting but also on the nature of the flow that drives it. In particular, they support an earlier suggestion that during forced wetting, an intense shear stress in the vicinity of the contact line can assist surface tension forces in promoting dynamic wetting, thus reducing the velocity-dependence of the contact angle. Hydrodynamic assist then appears as a natural consequence of wetting that emerges when the contact line is driven by a strong and highly confined flow. Our theoretical approach also provides a self-consistent model of molecular slip at the solid-liquid interface that enables its magnitude to be estimated from dynamic contact angle measurements. In addition, the model predicts how hydrodynamic assist and slip may be influenced by liquid viscosity and solid-liquid interactions.

  8. Progress in smooth particle hydrodynamics

    SciTech Connect

    Wingate, C.A.; Dilts, G.A.; Mandell, D.A.; Crotzer, L.A.; Knapp, C.E.

    1998-07-01

    Smooth Particle Hydrodynamics (SPH) is a meshless, Lagrangian numerical method for hydrodynamics calculations where calculational elements are fuzzy particles which move according to the hydrodynamic equations of motion. Each particle carries local values of density, temperature, pressure and other hydrodynamic parameters. A major advantage of SPH is that it is meshless, thus large deformation calculations can be easily done with no connectivity complications. Interface positions are known and there are no problems with advecting quantities through a mesh that typical Eulerian codes have. These underlying SPH features make fracture physics easy and natural and in fact, much of the applications work revolves around simulating fracture. Debris particles from impacts can be easily transported across large voids with SPH. While SPH has considerable promise, there are some problems inherent in the technique that have so far limited its usefulness. The most serious problem is the well known instability in tension leading to particle clumping and numerical fracture. Another problem is that the SPH interpolation is only correct when particles are uniformly spaced a half particle apart leading to incorrect strain rates, accelerations and other quantities for general particle distributions. SPH calculations are also sensitive to particle locations. The standard artificial viscosity treatment in SPH leads to spurious viscosity in shear flows. This paper will demonstrate solutions for these problems that they and others have been developing. The most promising is to replace the SPH interpolant with the moving least squares (MLS) interpolant invented by Lancaster and Salkauskas in 1981. SPH and MLS are closely related with MLS being essentially SPH with corrected particle volumes. When formulated correctly, JLS is conservative, stable in both compression and tension, does not have the SPH boundary problems and is not sensitive to particle placement. The other approach to

  9. Hydrodynamic efficiencies in implosion experiments

    NASA Astrophysics Data System (ADS)

    Koenig, Michel; Fabre, Edouard; Boudenne, Jean-Michel; Michard, Alain; Fews, P.

    1990-04-01

    Experiments on the implosion of high aspect ratio glass microballoons, filled with an equimolar mixture of 10 atmosphere D-T gas, aimed at determining hydrodynamic efficiencies, the characteristics (density and temperature) of the wall, are described. Experimental results for kinetic and thermal variations, obtained for 350 and 450 micrometer targets, at an absorbed laser power of about 120 J, are compared with values given by simulations with the FILM code. The comparison is made at the time of shock reflection on the internal wall of the shell. The use of X spectroscopy in such experiments is discussed.

  10. Hydrodynamic instability experiments and simulations

    SciTech Connect

    Dimonte, G.; Schneider, M.; Frerking, C.E.

    1995-07-01

    Richtmyer-Meshkov experiments are conducted on the Nova laser with strong radiatively driven shocks (Mach > 20) in planar, two-fluid targets with Atwood number A < 0. Single mode interfacial perturbations are used to test linear theory and 3D random perturbations are used to study turbulent mix. Rayleigh-Taylor experiments are conducted on a new facility called the Linear Electric Motor (LEM) in which macroscopic fluids are accelerated electromagnetically with arbitrary acceleration profiles. The initial experiments are described. Hydrodynamic simulations in 2D are in reasonable agreement with the experiments, but these studies show that simulations in 3D with good radiation transport and equation of state are needed.

  11. Hydrodynamic Synchronisation of Model Microswimmers

    NASA Astrophysics Data System (ADS)

    Putz, V. B.; Yeomans, J. M.

    2009-12-01

    We define a model microswimmer with a variable cycle time, thus allowing the possibility of phase locking driven by hydrodynamic interactions between swimmers. We find that, for extensile or contractile swimmers, phase locking does occur, with the relative phase of the two swimmers being, in general, close to 0 or π, depending on their relative position and orientation. We show that, as expected on grounds of symmetry, self T-dual swimmers, which are time-reversal covariant, do not phase-lock. We also discuss the phase behaviour of a line of tethered swimmers, or pumps. These show oscillations in their relative phases reminiscent of the metachronal waves of cilia.

  12. Disruptive Innovation in Numerical Hydrodynamics

    SciTech Connect

    Waltz, Jacob I.

    2012-09-06

    We propose the research and development of a high-fidelity hydrodynamic algorithm for tetrahedral meshes that will lead to a disruptive innovation in the numerical modeling of Laboratory problems. Our proposed innovation has the potential to reduce turnaround time by orders of magnitude relative to Advanced Simulation and Computing (ASC) codes; reduce simulation setup costs by millions of dollars per year; and effectively leverage Graphics Processing Unit (GPU) and future Exascale computing hardware. If successful, this work will lead to a dramatic leap forward in the Laboratory's quest for a predictive simulation capability.

  13. Hydrodynamics of post CHF region

    SciTech Connect

    Ishii, M.; De Jarlais, G.

    1984-04-01

    Among various two-phase flow regimes, the inverted flow in the post-dryout region is relatively less well understood due to its special heat transfer conditions. The review of existing data indicates further research is needed in the areas of basic hydrodynamics related to liquid core disintegration mechanisms, slug and droplet formations, entrainment, and droplet size distributions. In view of this, the inverted flow is studied in detail both analytically and experimentally. Criteria for initial flow regimes in the post-dryout region are given. Preliminary models for subsequent flow regime transition criteria are derived together with correlations for a mean droplet diameter based on the adiabatic simulation data.

  14. Numerical Hydrodynamics in General Relativity.

    PubMed

    Font, José A

    2000-01-01

    The current status of numerical solutions for the equations of ideal general relativistic hydrodynamics is reviewed. Different formulations of the equations are presented, with special mention of conservative and hyperbolic formulations well-adapted to advanced numerical methods. A representative sample of available numerical schemes is discussed and particular emphasis is paid to solution procedures based on schemes exploiting the characteristic structure of the equations through linearized Riemann solvers. A comprehensive summary of relevant astrophysical simulations in strong gravitational fields, including gravitational collapse, accretion onto black holes and evolution of neutron stars, is also presented.

  15. Foundation of Hydrodynamics of Strongly Interacting Systems

    SciTech Connect

    Wong, Cheuk-Yin

    2014-01-01

    Hydrodynamics and quantum mechanics have many elements in common, as the density field and velocity fields are common variables that can be constructed in both descriptions. Starting with the Schroedinger equation and the Klein-Gordon for a single particle in hydrodynamical form, we examine the basic assumptions under which a quantum system of particles interacting through their mean fields can be described by hydrodynamics.

  16. Microscale hydrodynamics near moving contact lines

    NASA Technical Reports Server (NTRS)

    Garoff, Stephen; Chen, Q.; Rame, Enrique; Willson, K. R.

    1994-01-01

    The hydrodynamics governing the fluid motions on a microscopic scale near moving contact lines are different from those governing motion far from the contact line. We explore these unique hydrodynamics by detailed measurement of the shape of a fluid meniscus very close to a moving contact line. The validity of present models of the hydrodynamics near moving contact lines as well as the dynamic wetting characteristics of a family of polymer liquids are discussed.

  17. Video enhancement of dental radiographic films

    SciTech Connect

    Van Dis, M.L.; Beck, F.M.; Miles, D.A. )

    1989-08-01

    A prototype video image display system, a real-time analog enhancer (RAE), was compared to conventional viewing conditions with the use of nonscreen dental films. When medium optical density films were evaluated, there was no significant difference in the number of radiographic details detected. Conventional viewing conditions allowed perception of more details when dark films were evaluated; however, the RAE unit allowed the perception of more details when light films were viewed.

  18. Low Cost High Volume Radiographic Inspection.

    DTIC Science & Technology

    1981-01-01

    for high rate production due to the high labor and film costs and excessive flow time. The development of a non-film radiographic inspection method was...understood. The major drawbacks to this technique are the high labor and material costs and long flow times. 4.3.1 PARAMETERS AFFECTING RESOLUTION The...provides computer control of the manual functions that are labor intensive or sensitive to human error. These primarily fall into the category of data

  19. Iterative Reconstruction of Coded Source Neutron Radiographs

    SciTech Connect

    Santos-Villalobos, Hector J; Bingham, Philip R; Gregor, Jens

    2012-01-01

    Use of a coded source facilitates high-resolution neutron imaging but requires that the radiographic data be deconvolved. In this paper, we compare direct deconvolution with two different iterative algorithms, namely, one based on direct deconvolution embedded in an MLE-like framework and one based on a geometric model of the neutron beam and a least squares formulation of the inverse imaging problem.

  20. Shaped Charge Jet Flash Radiograph Digitization

    DTIC Science & Technology

    2005-09-01

    radiograph digitization of shaped chare jets provides warhead designers with the data required for empirically based models , as well as the jet...characterization used for comparison with high rate continuum modeling . Reduced digitization results include jet tip velocity, jet accumulated length...using CALCOMP model 9500 digitizing tablet. It has the resolution of 0.25 x 10-3 in., accuracy of ± 0.003 in. and about 6 ft in length. The digitized

  1. Real-time radiographic inspection facility

    NASA Technical Reports Server (NTRS)

    Roberts, E., Jr.

    1977-01-01

    A real time radiographic inspection facility has been developed for nondestructive evaluation applications. It consists of an X-ray source, an X-ray sensitive television imaging system, an electronic analog image processing system, and a digital image processing system. The digital image processing system is composed of a computer with the necessary software to drive the overall facility. Descriptions are given of the design strategy, the facility's components, and its current capabilities.

  2. An improved method for simulating radiographs

    SciTech Connect

    Laguna, G.W.

    1986-09-30

    The parameters involved in generating actual radiographs and what can and cannot be modeled are examined in this report. Using the spectral distribution of the radiation source and the mass absorption curve for the material comprising the part to be modeled, the actual amount of radiation that would pass through the part and reach the film is determined. This method increases confidence in the results of the simulation and enables the modeling of parts made of multiple materials. (LEW)

  3. Thermal transport in a noncommutative hydrodynamics

    SciTech Connect

    Geracie, M. Son, D. T.

    2015-03-15

    We find the hydrodynamic equations of a system of particles constrained to be in the lowest Landau level. We interpret the hydrodynamic theory as a Hamiltonian system with the Poisson brackets between the hydrodynamic variables determined from the noncommutativity of space. We argue that the most general hydrodynamic theory can be obtained from this Hamiltonian system by allowing the Righi-Leduc coefficient to be an arbitrary function of thermodynamic variables. We compute the Righi-Leduc coefficient at high temperatures and show that it satisfies the requirements of particle-hole symmetry, which we outline.

  4. Artificial intelligence for analyzing orthopedic trauma radiographs.

    PubMed

    Olczak, Jakub; Fahlberg, Niklas; Maki, Atsuto; Razavian, Ali Sharif; Jilert, Anthony; Stark, André; Sköldenberg, Olof; Gordon, Max

    2017-07-06

    Background and purpose - Recent advances in artificial intelligence (deep learning) have shown remarkable performance in classifying non-medical images, and the technology is believed to be the next technological revolution. So far it has never been applied in an orthopedic setting, and in this study we sought to determine the feasibility of using deep learning for skeletal radiographs. Methods - We extracted 256,000 wrist, hand, and ankle radiographs from Danderyd's Hospital and identified 4 classes: fracture, laterality, body part, and exam view. We then selected 5 openly available deep learning networks that were adapted for these images. The most accurate network was benchmarked against a gold standard for fractures. We furthermore compared the network's performance with 2 senior orthopedic surgeons who reviewed images at the same resolution as the network. Results - All networks exhibited an accuracy of at least 90% when identifying laterality, body part, and exam view. The final accuracy for fractures was estimated at 83% for the best performing network. The network performed similarly to senior orthopedic surgeons when presented with images at the same resolution as the network. The 2 reviewer Cohen's kappa under these conditions was 0.76. Interpretation - This study supports the use for orthopedic radiographs of artificial intelligence, which can perform at a human level. While current implementation lacks important features that surgeons require, e.g. risk of dislocation, classifications, measurements, and combining multiple exam views, these problems have technical solutions that are waiting to be implemented for orthopedics.

  5. Clinical and radiographic maxillofacial features of pycnodysostosis

    PubMed Central

    Alves, Nilton; Cantín, Mario

    2014-01-01

    The aim of this study was to review of the literature to determine the radiographic and clinical maxillofacial features of pycnodysostosis emphasizing the main aspects of interest to the dentist in order to make them fit for the proper treatment of this population. It is important to make the diagnosis as early as possible in order to plan the treatment more suitable to provide a better life’s quality to the patients. The most frequent clinical maxillofacial features were: grooved palate, midfacial hypoplasia, mandibular hypoplasia and enamel hypoplasia. The most common radiographic maxillofacial features were: obtuse mandibular angle, frontal/parietal/occiptal bossing, open fontanels and sutures, multiple impacted teeth. The earlier diagnostic of pycnodysostosis has a fundamental role in general health of the patients. We consider that is very important that the dentist know recognize the radiographic and clinical maxillofacial features of pycnodysostosis, which allows correct treatment planning avoiding risks and ensuring better life’s quality to the patients. PMID:24753741

  6. Unsupervised segmentation of lungs from chest radiographs

    NASA Astrophysics Data System (ADS)

    Ghosh, Payel; Antani, Sameer K.; Long, L. Rodney; Thoma, George R.

    2012-03-01

    This paper describes our preliminary investigations for deriving and characterizing coarse-level textural regions present in the lung field on chest radiographs using unsupervised grow-cut (UGC), a cellular automaton based unsupervised segmentation technique. The segmentation has been performed on a publicly available data set of chest radiographs. The algorithm is useful for this application because it automatically converges to a natural segmentation of the image from random seed points using low-level image features such as pixel intensity values and texture features. Our goal is to develop a portable screening system for early detection of lung diseases for use in remote areas in developing countries. This involves developing automated algorithms for screening x-rays as normal/abnormal with a high degree of sensitivity, and identifying lung disease patterns on chest x-rays. Automatically deriving and quantitatively characterizing abnormal regions present in the lung field is the first step toward this goal. Therefore, region-based features such as geometrical and pixel-value measurements were derived from the segmented lung fields. In the future, feature selection and classification will be performed to identify pathological conditions such as pulmonary tuberculosis on chest radiographs. Shape-based features will also be incorporated to account for occlusions of the lung field and by other anatomical structures such as the heart and diaphragm.

  7. Hydrodynamic noise and surface compliance

    NASA Astrophysics Data System (ADS)

    Vonwinkle, W. A.; Fitzgerald, J.; Carey, W. M.; Bakewell, H. P., Jr.

    1982-09-01

    This document discusses the role of surface compliance on hydrodynamic noise and is based on a review of theoretical and experimental flow-noise investigations. Basic flow-noise theories are discussed in light of compliant surface boundary conditions. A comprehensive review of the experimental results of compliant surface flow-noise experiments is presented. Surface compliance can effect the measured noise; however, the compliance of the surfaces used in previous experiments was not adequately described. Consequently, results varied and showed a marked, but undefined, temperature dependence. The characterization of the complex surface compliance is discussed, including effects of frequency and temperature. A method that characterizes surface compliance is denoted and used to measure the properties of several mammalian tissues. Then a discussion and a comparison of these results to the wavenumber spectra data follows. An experimental investigation of the effect of surface compliance on the hydrodynamic noise is proposed by means of measurement of material properties, measurement of wall pressure fluctuation spectra, holographic representation of the surface displacement, and characterization of the TBL boundary layer to determine the magnitude and role of complex surface compliance of the TBL and its flow noise.

  8. Hydrodynamic forces on piggyback pipelines

    SciTech Connect

    Jakobsen, M.L.; Sayer, P.

    1995-12-31

    An increasing number of new offshore pipelines have been designed as bundles, mainly because of overall cost reductions. One popular way of combining two pipelines with different diameters is the piggyback configuration, with the smaller pipeline strapped on top of the main pipeline. The external hydrodynamic forces on this combination are at present very roughly estimated; pipeline engineers need more data to support their designs. This paper presents experimental results for the in-line hydrodynamic loading on three different piggyback set-ups. The models comprised a 0.4 m main pipeline, and three piggyback pipelines with diameters of 0.038 m, 0.059 m and 0.099 m. Each small pipeline was separately mounted to the main pipeline, with a gap equal to its own diameter. These model sizes lie approximately between half- and full-scale. Experiments were undertaken for K{sub C} between 5 and 42, and R{sub e} in the range 0.0 * 10{sup 4} to 8.5 * 10{sup 5}. The results based on Morison`s equation indicate that a simple addition of the separate forces acting on each cylinder underestimates the actual force by up to 35% at low K{sub C} (< {approximately} 10) and by as much as 100% in the drag-dominated regime (K{sub C} > {approximately} 20).

  9. Inducer Hydrodynamic Load Measurement Devices

    NASA Technical Reports Server (NTRS)

    Skelley, Stephen E.; Zoladz, Thomas F.

    2002-01-01

    Marshall Space Flight Center (MSFC) has demonstrated two measurement devices for sensing and resolving the hydrodynamic loads on fluid machinery. The first - a derivative of the six component wind tunnel balance - senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This "rotating balance" was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining both the amplitude and frequency content associated with operating in various cavitation modes. The second device - a high frequency response pressure transducer surface mounted on a rotating component - was merely an extension of existing technology for application in water. MSFC has recently completed experimental evaluations of both the rotating balance and surface-mount transducers in a water test loop. The measurement bandwidth of the rotating balance was severely limited by the relative flexibility of the device itself, resulting in an unexpectedly low structural bending mode and invalidating the higher frequency response data. Despite these limitations, measurements confirmed that the integrated loads on the four-bladed inducer respond to both cavitation intensity and cavitation phenomena. Likewise, the surface-mount pressure transducers were subjected to a range of temperatures and flow conditions in a non-rotating environment to record bias shifts and transfer functions between the transducers and a reference device. The pressure transducer static performance was within manufacturer's specifications and dynamic response accurately followed that of the reference.

  10. The hydrodynamics of lamprey locomotion

    NASA Astrophysics Data System (ADS)

    Leftwich, Megan C.

    The lamprey, an anguilliform swimmer, propels itself by undulating most of its body. This type of swimming produces flow patterns that are highly three-dimensional in nature and not very well understood. However, substantial previous work has been done to understand two-dimensional unsteady propulsion, the possible wake structures and thrust performance. Limited studies of three-dimensional propulsors with simple geometries have displayed the importance of the third dimension in designing unsteady swimmers. Some of the results of those studies, primarily the ways in which vorticity is organized in the wake region, are seen in lamprey swimming as well. In the current work, the third dimension is not the only important factor, but complex geometry and body undulations also contribute to the hydrodynamics. Through dye flow visualization, particle induced velocimetry and pressure measurements, the hydrodynamics of anguilliform swimming are studied using a custom built robotic lamprey. These studies all indicate that the undulations of the body are not producing thrust. Instead, it is the tail which acts to propel the animal. This conclusion led to further investigation of the tail, specifically the role of varying tail flexibility on hydrodymnamics. It is found that by making the tail more flexible, one decreases the coherence of the vorticity in the lamprey's wake. Additional flexibility also yields less thrust.

  11. Hydromechanical transmission with hydrodynamic drive

    DOEpatents

    Orshansky, Jr., deceased, Elias; Weseloh, William E.

    1979-01-01

    This transmission has a first planetary gear assembly having first input means connected to an input shaft, first output means, and first reaction means, and a second planetary gear assembly having second input means connected to the first input means, second output means, and second reaction means connected directly to the first reaction means by a reaction shaft. First clutch means, when engaged, connect the first output means to an output shaft in a high driving range. A hydrodynamic drive is used; for example, a torque converter, which may or may not have a stationary case, has a pump connected to the second output means, a stator grounded by an overrunning clutch to the case, and a turbine connected to an output member, and may be used in a starting phase. Alternatively, a fluid coupling or other type of hydrodynamic drive may be used. Second clutch means, when engaged, for connecting the output member to the output shaft in a low driving range. A variable-displacement hydraulic unit is mechanically connected to the input shaft, and a fixed-displacement hydraulic unit is mechanically connected to the reaction shaft. The hydraulic units are hydraulically connected together so that when one operates as a pump the other acts as a motor, and vice versa. Both clutch means are connected to the output shaft through a forward-reverse shift arrangement. It is possible to lock out the torque converter after the starting phase is over.

  12. Inducer Hydrodynamic Load Measurement Devices

    NASA Technical Reports Server (NTRS)

    Skelley, Stephen E.; Zoladz, Thomas F.; Turner, Jim (Technical Monitor)

    2002-01-01

    Marshall Space Flight Center (MSFC) has demonstrated two measurement devices for sensing and resolving the hydrodynamic loads on fluid machinery. The first - a derivative of the six-component wind tunnel balance - senses the forces and moments on the rotating device through a weakened shaft section instrumented with a series of strain gauges. This rotating balance was designed to directly measure the steady and unsteady hydrodynamic loads on an inducer, thereby defining both the amplitude and frequency content associated with operating in various cavitation modes. The second device - a high frequency response pressure transducer surface mounted on a rotating component - was merely an extension of existing technology for application in water. MSFC has recently completed experimental evaluations of both the rotating balance and surface-mount transducers in a water test loop. The measurement bandwidth of the rotating balance was severely limited by the relative flexibility of the device itself, resulting in an unexpectedly low structural bending mode and invalidating the higher-frequency response data. Despite these limitations, measurements confirmed that the integrated loads on the four-bladed inducer respond to both cavitation intensity and cavitation phenomena. Likewise, the surface-mount pressure transducers were subjected to a range of temperatures and flow conditions in a non-rotating environment to record bias shifts and transfer functions between the transducers and a reference device. The pressure transducer static performance was within manufacturer's specifications and dynamic response accurately followed that of the reference.

  13. Fluctuating Hydrodynamics of Electrolytes Solutions

    NASA Astrophysics Data System (ADS)

    Peraud, Jean-Philippe; Nonaka, Andy; Chaudhri, Anuj; Bell, John B.; Donev, Aleksandar; Garcia, Alejandro L.

    2016-11-01

    In this work, we develop a numerical method for multicomponent solutions featuring electrolytes, in the context of fluctuating hydrodynamics as modeled by the Landau-Lifshitz Navier Stokes equations. Starting from a previously developed numerical scheme for multicomponent low Mach number fluctuating hydrodynamics, we study the effect of the additional forcing terms induced by charged species. We validate our numerical approach with additional theoretical considerations and with examples involving sodium-chloride solutions, with length scales close to Debye length. In particular, we show how charged species modify the structure factors of the fluctuations, both in equilibrium and non-equilibrium (giant fluctuations) systems, and show that the former is consistent with Debye-Huckel theory. We also discuss the consistency of this approach with the electroneutral approximation in regimes where characteristic length scales are significantly larger than the Debye length. Finally, we use this method to explore a type of electrokinetic instability. This work was supported by the U.S. Department of Energy, Office of Science, Office of Advanced Scientific Computing Research,.

  14. Hydrodynamic dispersion within porous biofilms

    NASA Astrophysics Data System (ADS)

    Davit, Y.; Byrne, H.; Osborne, J.; Pitt-Francis, J.; Gavaghan, D.; Quintard, M.

    2013-01-01

    Many microorganisms live within surface-associated consortia, termed biofilms, that can form intricate porous structures interspersed with a network of fluid channels. In such systems, transport phenomena, including flow and advection, regulate various aspects of cell behavior by controlling nutrient supply, evacuation of waste products, and permeation of antimicrobial agents. This study presents multiscale analysis of solute transport in these porous biofilms. We start our analysis with a channel-scale description of mass transport and use the method of volume averaging to derive a set of homogenized equations at the biofilm-scale in the case where the width of the channels is significantly smaller than the thickness of the biofilm. We show that solute transport may be described via two coupled partial differential equations or telegrapher's equations for the averaged concentrations. These models are particularly relevant for chemicals, such as some antimicrobial agents, that penetrate cell clusters very slowly. In most cases, especially for nutrients, solute penetration is faster, and transport can be described via an advection-dispersion equation. In this simpler case, the effective diffusion is characterized by a second-order tensor whose components depend on (1) the topology of the channels' network; (2) the solute's diffusion coefficients in the fluid and the cell clusters; (3) hydrodynamic dispersion effects; and (4) an additional dispersion term intrinsic to the two-phase configuration. Although solute transport in biofilms is commonly thought to be diffusion dominated, this analysis shows that hydrodynamic dispersion effects may significantly contribute to transport.

  15. Low energy chronic traumatic spondylolisthesis of the axis.

    PubMed

    Dunn, Conor J; Mease, Samuel; Issa, Kimona; Sinha, Kumar; Emami, Arash

    2017-07-21

    The aim of this study is to present a unique case of a patient who presented to our Emergency Department with evidence of a chronic traumatic spondylolisthesis of the axis with severe displacement treated with anterior cervical discectomy and fusion (ACDF) of C2-C3 as well as and posterior cervical fusion (PCF) of C1-C3. One patient with an untreated traumatic spondylolisthesis of the axis with Levine type II injury pattern and 1.2 cm of anterior subluxation underwent ACDF C2-C3 and PCF C1-C3. The patient recovered well, radiographs demonstrated reduction of the anterior subluxation, and the patient reported a neck disability index (NDI) score of 20 at 6-month follow-up with full neurologic function intact. The patient was then lost to follow-up. In this report, we present an alcoholic patient with a history of many falls who presented with a Levine type II traumatic spondylolisthesis of the axis with signs of chronicity seen on magnetic resonance imaging (MRI). We were able to partially reduce the anterior displacement with traction, but needed both anterior and posterior cervical approaches to achieve adequate reduction and stabilization of the injury.

  16. The forensic radiographer: a new member in the medicolegal team.

    PubMed

    Schneider, Benjamin; Chevallier, Christine; Dominguez, Alejandro; Bruguier, Christine; Elandoy, Cristèle; Mangin, Patrice; Grabherr, Silke

    2012-03-01

    Multidetector computed tomography is becoming more widespread in forensic medicine. In most services, autopsy assistants perform the radiological examination. We introduced professional radiographers into the legal medicine service and hypothesized they would also be able to take over duties currently reserved for other specialists. The aims of this study were to evaluate if radiographers could be trained as "forensic radiographers" by (1) integrating graduated medical radiographers into the legal medicine service, (2) investigating the advantages of this collaboration, and (3) defining the duties of the forensic radiographers.The study was performed prospectively on a group of 8 recruited radiographers who underwent a testing period with special training. They learned the basics of medicolegal case treatment, the autonomous execution of postmortem computed tomography angiography, and postprocessing of data. Seven of 8 radiographers finished the training and were integrated into our service. Although all radiographers were able to fulfill the duties demanded after the training period, some radiographers could not enter or complete the program because they were unable to work with dead bodies.Our study presents the advantages of integrating radiographers into the medicolegal team and proposes how to train the forensic radiographers. In addition, the duties and responsibilities of these new specialists are defined.

  17. Errors in radiographic interpretation made by veterinary students.

    PubMed

    Lamb, C R; Pfeiffer, D U; Mantis, P

    2007-01-01

    As a means of identifying student weaknesses in radiographic interpretation that could be used as foci for teaching, a cohort of 96 students joining the final-year radiology rotation were randomly allocated to one of three radiographic interpretation quizzes, each based on radiographs of small-animal patients together with the signalment and a brief, relevant history. Students' quiz scores were analyzed by multiple logistic regression, using an outcome variable with the score for each item as numerator and maximum possible mark as denominator. Students' median quiz score was 49% of the maximum (range 23-80%). Students were more likely to gain a mark for items based on abnormal radiographs than for those based on normal radiographs (odds ratio 3.4, p < 0.001). Skeletal radiographs were associated with lower scores (OR 0.75, p = 0.03). The fewest marks were awarded for interpretation of a radiograph of a normal canine stifle and interpretation of a radiograph of a normal canine pelvis; these items were misinterpreted as abnormal by 86% and 80% of the students, respectively. Students' tendency to over-interpret normal radiographs may reflect a lack of knowledge of radiographic anatomy or an unrealistically high expectation that the radiographs are abnormal.

  18. Radiographic evaluation of the modified Brunelli technique versus a scapholunotriquetral transosseous tenodesis technique for scapholunate dissociation.

    PubMed

    Hsu, Jennifer W; Kollitz, Kathleen M; Jegapragasan, Mithulan; Huang, Jerry I

    2014-06-01

    To compare reduction of the scapholunate articulation using a transosseous tenodesis through the scaphoid, lunate, and triquetrum (SLT) with the modified Brunelli technique (MBT) in a cadaver model, as measured by scapholunate (SL) angle and diastasis on radiographs. Twelve fresh-frozen cadaveric wrists were radiographically examined in a neutral posture, ulnar deviation, and clenched fist position. The SL angle and diastasis were recorded in each position with the SL ligament intact, after sectioning the ligament and secondary restraints, and after reconstruction by either the MBT (6 wrists) or SLT technique (6 wrists). Wrists were cycled through their maximum flexion and extension arc 100 times to simulate wrist motion after ligament sectioning and reconstruction. After sectioning and cycling, all wrists demonstrated radiographic evidence of SL diastasis. After ligament reconstruction and cycling, there was no statistically significant difference in diastasis in the MBT reconstructions compared with the SLT reconstructions (3.0 vs 2.4 mm). The SLT group demonstrated better maintenance of the restored SL angle than the MBT reconstructions. In this cadaveric model, both MBT and SLT reconstructions restored anatomic parameters in the SL joint, with correction of SL diastasis and SL angle. Future studies to assess the clinical outcomes of SLT tenodesis in patients with chronic SL disruptions are important. The SLT tenodesis, with a central biologic tether along the SL axis and dorsal reinforcement, may prove clinically useful. Copyright © 2014 American Society for Surgery of the Hand. Published by Elsevier Inc. All rights reserved.

  19. Pediatric cervical spine in emergency: radiographic features of normal anatomy, variants and pitfalls.

    PubMed

    Adib, Omar; Berthier, Emeline; Loisel, Didier; Aubé, Christophe

    2016-12-01

    Injuries of the cervical spine are uncommon in children. The distribution of injuries, when they do occur, differs according to age. Young children aged less than 8 years usually have upper cervical injuries because of the anatomic and biomechanical properties of their immature spine, whereas older children, whose biomechanics more closely resemble those of adults, are prone to lower cervical injuries. In all cases, the pediatric cervical spine has distinct radiographic features, making the emergency radiological analysis of it difficult. Such features as hypermobility between C2 and C3, pseudospread of the atlas on the axis, pseudosubluxation, the absence of lordosis, anterior wedging of vertebral bodies, pseudowidening of prevertebral soft tissue and incomplete ossification of synchondrosis can be mistaken for traumatic injuries. The interpretation of a plain radiograph of the pediatric cervical spine following trauma must take into account the age of the child, the location of the injury and the mechanism of trauma. Comprehensive knowledge of the specific anatomy and biomechanics of the childhood spine is essential for the diagnosis of suspected cervical spine injury. With it, the physician can, on one hand, differentiate normal physes or synchondroses from pathological fractures or ligamentous disruptions and, on the other, identify any possible congenital anomalies that may also be mistaken for injury. Thus, in the present work, we discuss normal radiological features of the pediatric cervical spine, variants that may be encountered and pitfalls that must be avoided when interpreting plain radiographs taken in an emergency setting following trauma.

  20. Frontal alignment in total knee arthroplasty. Comparative study between radiographic measurement and surgical navigation.

    PubMed

    Hernandez-Vaquero, D; Noriega-Fernandez, A; Suarez-Vazquez, A; Roncero-Gonzalez, S; Sierra-Pereira, A A; Gil-Martinez, L; Fernandez-Carreira, J M

    To establish the concordance between angulation of the femoro-tibial mechanical axis measured with x-rays and surgical navigation in both the pre and postoperative period after a total knee arthroplasty (TKA) was implanted. Pre and postoperative measurements were analyzed in 88 TKA of the same model and all performed with the same surgical navigation system. The mechanical frontal angle (MFA) and femoro-tibial anatomic angle were measured before and after the TKA. The angulation was digitally measured with a teleradiography. In the navigation, the femoro-tibial angle at rest, forced varus and valgus were registered and the average of these three measurements was calculated. The mean preoperative MFA measured on the radiograph was 4.55°. The mean of the same angle measured on the postoperative radiograph was 1.72°, (p=0.05). The mean of the MFA measured with navigation before TKA was 3.12° and after the implant with navigation was 0.53 (P=.013). The concordance coefficient between the MFA in teleradiography and in navigation was 0.869 (P<.001) preoperatively and 0.709 postoperatively (P=.017). We found a strong concordance between radiographic and surgical navigation measurements of the MFA. This may imply that teleradiography is not necessary when using surgical navigation in TKA. Copyright © 2017 SECOT. Publicado por Elsevier España, S.L.U. All rights reserved.

  1. A method of smoothed particle hydrodynamics using spheroidal kernels

    NASA Technical Reports Server (NTRS)

    Fulbright, Michael S.; Benz, Willy; Davies, Melvyn B.

    1995-01-01

    We present a new method of three-dimensional smoothed particle hydrodynamics (SPH) designed to model systems dominated by deformation along a preferential axis. These systems cause severe problems for SPH codes using spherical kernels, which are best suited for modeling systems which retain rough spherical symmetry. Our method allows the smoothing length in the direction of the deformation to evolve independently of the smoothing length in the perpendicular plane, resulting in a kernel with a spheroidal shape. As a result the spatial resolution in the direction of deformation is significantly improved. As a test case we present the one-dimensional homologous collapse of a zero-temperature, uniform-density cloud, which serves to demonstrate the advantages of spheroidal kernels. We also present new results on the problem of the tidal disruption of a star by a massive black hole.

  2. A method of smoothed particle hydrodynamics using spheroidal kernels

    NASA Technical Reports Server (NTRS)

    Fulbright, Michael S.; Benz, Willy; Davies, Melvyn B.

    1995-01-01

    We present a new method of three-dimensional smoothed particle hydrodynamics (SPH) designed to model systems dominated by deformation along a preferential axis. These systems cause severe problems for SPH codes using spherical kernels, which are best suited for modeling systems which retain rough spherical symmetry. Our method allows the smoothing length in the direction of the deformation to evolve independently of the smoothing length in the perpendicular plane, resulting in a kernel with a spheroidal shape. As a result the spatial resolution in the direction of deformation is significantly improved. As a test case we present the one-dimensional homologous collapse of a zero-temperature, uniform-density cloud, which serves to demonstrate the advantages of spheroidal kernels. We also present new results on the problem of the tidal disruption of a star by a massive black hole.

  3. Towing Tank Measurements of Hydrodynamic Performance of a Horizontal Axis Tidal Turbine Under Unsteady Flow Conditions

    DTIC Science & Technology

    2013-05-10

    torque using the same principles an airplane uses to remain in the air. The blades act as hydrofoils , creating lift and using the lift to turn the shaft...The analysis of the lifting force from a hydrofoil is complex, but the basic concept involves the relationship between velocity and pressure. The

  4. Three axis attitude control system

    NASA Technical Reports Server (NTRS)

    Studer, Philip A. (Inventor)

    1988-01-01

    A three-axis attitude control system for an orbiting body comprised of a motor driven flywheel supported by a torque producing active magnetic bearing is described. Free rotation of the flywheel is provided about its central axis and together with limited angular torsional deflections of the flywheel about two orthogonal axes which are perpendicular to the central axis. The motor comprises an electronically commutated DC motor, while the magnetic bearing comprises a radially servoed permanent magnet biased magnetic bearing capable of producing cross-axis torques on the flywheel. Three body attitude sensors for pitch, yaw and roll generate respective command signals along three mutually orthogonal axes (x, y, z) which are coupled to circuit means for energizing a set of control coils for producing torques about two of the axes (x and y) and speed control of the flywheel about the third (z) axis. An energy recovery system, which is operative during motor deceleration, is also included which permits the use of a high-speed motor to perform effectively as a reactive wheel suspended in the magnetic bearing.

  5. Radiographic study on the anatomical characteristics of the proximal femur in Brazilian adults☆

    PubMed Central

    de Farias, Tércio Henrique Soares; Borges, Vinícius Quadros; de Souza, Eduardo Soares; Miki, Natália; Abdala, Fernando

    2015-01-01

    Objective To ascertain the geometry of the femur in the Brazilian population by means of a radiographic study and to correlate the values with regard to sex and right/left side. Methods Five hundred anteroposterior radiographs of the pelvis of skeletally mature patients (250 of each sex) who did not present any osteoarthrosis, fractures or tumoral or infectious lesions were analyzed. The length and width of the femoral neck, length of the femoral axis, neck-shaft angle and femoral offset were measured. Results The following means were observed: 36.54 mm for the length of the femoral neck; 37.48 mm for the width of the femoral neck; 108.42 mm for the length of the femoral axis; 130.47° for the neck-shaft angle; and 44.4 mm for the femoral offset. Conclusion The mean values for the main measurements on the proximal femur in Brazilians differed from those of previous studies. It could also be shown that there was a statistically significant mean difference between men and women for all the variables, both on the left and on the right side, and that the men had greater means than the women. PMID:26229891

  6. Hydrodynamics, Fungal Physiology, and Morphology.

    PubMed

    Serrano-Carreón, L; Galindo, E; Rocha-Valadéz, J A; Holguín-Salas, A; Corkidi, G

    2015-01-01

    Filamentous cultures, such as fungi and actinomycetes, contribute substantially to the pharmaceutical industry and to enzyme production, with an annual market of about 6 billion dollars. In mechanically stirred reactors, most frequently used in fermentation industry, microbial growth and metabolite productivity depend on complex interactions between hydrodynamics, oxygen transfer, and mycelial morphology. The dissipation of energy through mechanically stirring devices, either flasks or tanks, impacts both microbial growth through shearing forces on the cells and the transfer of mass and energy, improving the contact between phases (i.e., air bubbles and microorganisms) but also causing damage to the cells at high energy dissipation rates. Mechanical-induced signaling in the cells triggers the molecular responses to shear stress; however, the complete mechanism is not known. Volumetric power input and, more importantly, the energy dissipation/circulation function are the main parameters determining mycelial size, a phenomenon that can be explained by the interaction of mycelial aggregates and Kolmogorov eddies. The use of microparticles in fungal cultures is also a strategy to increase process productivity and reproducibility by controlling fungal morphology. In order to rigorously study the effects of hydrodynamics on the physiology of fungal microorganisms, it is necessary to rule out the possible associated effects of dissolved oxygen, something which has been reported scarcely. At the other hand, the processes of phase dispersion (including the suspended solid that is the filamentous biomass) are crucial in order to get an integral knowledge about biological and physicochemical interactions within the bioreactor. Digital image analysis is a powerful tool for getting relevant information in order to establish the mechanisms of mass transfer as well as to evaluate the viability of the mycelia. This review focuses on (a) the main characteristics of the two most

  7. Accuracy and Reproducibility of Radiographic Images for Assessing Crestal Bone Height of Implants Using the Precision Implant X-ray Locator (PIXRL) Device.

    PubMed

    Malloy, Kyle A; Wadhwani, Chandur; McAllister, Bradley; Wang, Mansen; Katancik, James A

    Assessment of crestal bone levels around implants is essential to monitor success and health. This is best accomplished with intraoral radiographs exposed at 90 degrees to the long axis of the implant, but this can be challenging to achieve clinically. Radiographic paralleling devices produce orthogonal radiographs but traditionally have required access to the implant body for each exposure. This study was conducted to determine if use of the Precision Implant X-ray Locator (PIXRL), a radiographic paralleling device that indexes the implant at the time of surgical placement, can produce orthogonal radiographs of dental implants more accurately than traditional radiologic techniques for assessing crestal bone levels. Three dental implants were inserted in dry human skulls in supracrestal positions to simulate crestal bone loss (maxillary right first premolar [site 14], maxillary right central incisor [site 11], and mandibular left second premolar [site 35]). The implants were masked with a soft tissue moulage and restored with provisional restorations. Four dental assistants exposed six radiographs using their usual and customary technique and six using the PIXRL device for each implant. A single examiner measured crestal bone levels on the radiographs relative to the implant platform shoulder on the mesial and distal of each implant. Recorded measurements were compared to the known values. Statistical analysis was completed using a generalized linear regression model to analyze the differences, and post-hoc comparisons with pairwise adjustment were applied. The images produced using the PIXRL device were more accurate overall compared to traditional techniques and were also more consistent. The greater degree of accuracy was statistically significant for all sites with the exception of the mesial measurements of the implant at site 11. This study demonstrates that the use of the PIXRL device can assist clinicians in obtaining more accurate orthogonal radiographs

  8. Relativistic Hydrodynamics for Heavy-Ion Collisions

    ERIC Educational Resources Information Center

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  9. Hydrodynamic description for ballistic annihilation systems

    SciTech Connect

    Garcia de Soria, Maria Isabel; Trizac, Emmanuel; Maynar, Pablo; Schehr, Gregory; Barrat, Alain

    2009-01-21

    The problem of the validity of a hydrodynamic description for a system in which there are no collisional invariants is addressed. Hydrodynamic equations have been derived and successfully tested against simulation data for a system where particles annihilate with a probability p, or collide elastically otherwise. The response of the system to a linear perturbation is analyzed as well.

  10. Hydrodynamic models of a Cepheid atmosphere

    NASA Technical Reports Server (NTRS)

    Karp, A. H.

    1975-01-01

    Instead of computing a large number of coarsely zoned hydrodynamic models covering the entire atmospheric instability strip, the author computed a single model as well as computer limitations allow. The implicit hydrodynamic code of Kutter and Sparks was modified to include radiative transfer effects in optically thin zones.

  11. Relativistic Hydrodynamics for Heavy-Ion Collisions

    ERIC Educational Resources Information Center

    Ollitrault, Jean-Yves

    2008-01-01

    Relativistic hydrodynamics is essential to our current understanding of nucleus-nucleus collisions at ultrarelativistic energies (current experiments at the Relativistic Heavy Ion Collider, forthcoming experiments at the CERN Large Hadron Collider). This is an introduction to relativistic hydrodynamics for graduate students. It includes a detailed…

  12. Oscillatory hydrodynamic flow induced by chemical waves

    NASA Astrophysics Data System (ADS)

    Miike, Hidetoshi; Müller, Stefan C.; Hess, Benno

    1988-05-01

    Hydrodynamic flows in a reactive liquid induced by the propagation of waves of chemical activity are investigated for the ferroin-catalyzed Belousov-Zhabotinskii reaction in thin layers by microscope video imaging techniques. The motion of added polystyrene spheres is observed with laser light illumination. Oscillations in the hydrodynamic flow were detected in rotating spiral waves with an open liquid/gas interface.

  13. Measurement of the hydrodynamic resistance of microdroplets.

    PubMed

    Jakiela, Slawomir

    2016-10-07

    Here, we demonstrate a novel method of measurement which determines precisely the hydrodynamic resistance of a droplet flowing through a channel. The obtained results show that the hydrodynamic resistance of a droplet in a microchannel achieves its maximum for lengths of the droplet ranging from 3w to 4w and that interactions between beads in a train exist.

  14. Non-boost-invariant dissipative hydrodynamics

    NASA Astrophysics Data System (ADS)

    Florkowski, Wojciech; Ryblewski, Radoslaw; Strickland, Michael; Tinti, Leonardo

    2016-12-01

    The one-dimensional non-boost-invariant evolution of the quark-gluon plasma, presumably produced during the early stages of heavy-ion collisions, is analyzed within the frameworks of viscous and anisotropic hydrodynamics. We neglect transverse dynamics and assume homogeneous conditions in the transverse plane but, differently from Bjorken expansion, we relax longitudinal boost invariance in order to study the rapidity dependence of various hydrodynamical observables. We compare the results obtained using several formulations of second-order viscous hydrodynamics with a recent approach to anisotropic hydrodynamics, which treats the large initial pressure anisotropy in a nonperturbative fashion. The results obtained with second-order viscous hydrodynamics depend on the particular choice of the second-order terms included, which suggests that the latter should be included in the most complete way. The results of anisotropic hydrodynamics and viscous hydrodynamics agree for the central hot part of the system, however, they differ at the edges where the approach of anisotropic hydrodynamics helps to control the undesirable growth of viscous corrections observed in standard frameworks.

  15. Update on Thermal and Hydrodynamic Simulations on LMJ Cryogenic Targets

    SciTech Connect

    Moll, G.; Charton, S.

    2004-03-15

    The temperature of the cryogenic target inside the hohlraum has been studied with a computational fluid dynamics code (FLUENT). Specific models have been developed and used for both thermal and hydrodynamic calculations.With thermal calculations only, we first have found the optimum heat flux required to counteract the effect of the laser entrance windows. This heat flux is centered on the hohlraum wall along the axis of revolution. With this heat flux, the temperature surface profiles of the capsule and the DT ice layer have been significantly reduced. Second, the sensitivity of the target temperature profiles (capsule and DT layer) relatively to capsule displacement has been determined. Thirdly, the effect of the shield extraction (shield surrounding the cryogenic structure) has been studied and has indicated that the target lifetime before the laser shot is less than 1s. Meanwhile, with hydrodynamic simulations, we have investigated the surface temperature profiles alteration due to He and H{sub 2} mixture convection within the hohlraum.In order to find out the variations between different configurations, results of these studies are given with seven significant digit outputs. Those results only indicate a trend because of the material's properties incertitude and the code approximation.

  16. SPHRAY: A Smoothed Particle Hydrodynamics Ray Tracer for Radiative Transfer

    NASA Astrophysics Data System (ADS)

    Altay, Gabriel; Croft, Rupert A. C.; Pelupessy, Inti

    2011-03-01

    SPHRAY, a Smoothed Particle Hydrodynamics (SPH) ray tracer, is designed to solve the 3D, time dependent, radiative transfer (RT) equations for arbitrary density fields. The SPH nature of SPHRAY makes the incorporation of separate hydrodynamics and gravity solvers very natural. SPHRAY relies on a Monte Carlo (MC) ray tracing scheme that does not interpolate the SPH particles onto a grid but instead integrates directly through the SPH kernels. Given initial conditions and a description of the sources of ionizing radiation, the code will calculate the non-equilibrium ionization state (HI, HII, HeI, HeII, HeIII, e) and temperature (internal energy/entropy) of each SPH particle. The sources of radiation can include point like objects, diffuse recombination radiation, and a background field from outside the computational volume. The MC ray tracing implementation allows for the quick introduction of new physics and is parallelization friendly. A quick Axis Aligned Bounding Box (AABB) test taken from computer graphics applications allows for the acceleration of the raytracing component. We present the algorithms used in SPHRAY and verify the code by performing all the test problems detailed in the recent Radiative Transfer Comparison Project of Iliev et. al. The Fortran 90 source code for SPHRAY and example SPH density fields are made available online.

  17. Vertical axis wind turbine airfoil

    DOEpatents

    Krivcov, Vladimir; Krivospitski, Vladimir; Maksimov, Vasili; Halstead, Richard; Grahov, Jurij Vasiljevich

    2012-12-18

    A vertical axis wind turbine airfoil is described. The wind turbine airfoil can include a leading edge, a trailing edge, an upper curved surface, a lower curved surface, and a centerline running between the upper surface and the lower surface and from the leading edge to the trailing edge. The airfoil can be configured so that the distance between the centerline and the upper surface is the same as the distance between the centerline and the lower surface at all points along the length of the airfoil. A plurality of such airfoils can be included in a vertical axis wind turbine. These airfoils can be vertically disposed and can rotate about a vertical axis.

  18. Hydrodynamic enhanced dielectrophoretic particle trapping

    DOEpatents

    Miles, Robin R.

    2003-12-09

    Hydrodynamic enhanced dielectrophoretic particle trapping carried out by introducing a side stream into the main stream to squeeze the fluid containing particles close to the electrodes producing the dielelectrophoretic forces. The region of most effective or the strongest forces in the manipulating fields of the electrodes producing the dielectrophoretic forces is close to the electrodes, within 100 .mu.m from the electrodes. The particle trapping arrangement uses a series of electrodes with an AC field placed between pairs of electrodes, which causes trapping of particles along the edges of the electrodes. By forcing an incoming flow stream containing cells and DNA, for example, close to the electrodes using another flow stream improves the efficiency of the DNA trapping.

  19. Radiation hydrodynamics in solar flares

    SciTech Connect

    Fisher, G.H.

    1985-10-18

    Solar flares are rather violent and extremely complicated phenomena, and it should be made clear at the outset that a physically complete picture describing all aspects of flares does not exist. From the wealth of data which is available, it is apparent that many different types of physical processes are involved during flares: energetic particle acceleration, rapid magnetohydrodynamic motion of complex field structures, magnetic reconnection, violent mass motion along magnetic field lines, and the heating of plasma to tens of millions of degrees, to name a few. The goal of this paper is to explore just one aspect of solar flares, namely, the interaction of hydrodynamics and radiation processes in fluid being rapidly heated along closed magnetic field lines. The models discussed are therefore necessarily restrictive, and will address only a few of the observed or observable phenomena. 46 refs., 6 figs.

  20. Integration of quantum hydrodynamical equation

    NASA Astrophysics Data System (ADS)

    Ulyanova, Vera G.; Sanin, Andrey L.

    2007-04-01

    Quantum hydrodynamics equations describing the dynamics of quantum fluid are a subject of this report (QFD).These equations can be used to decide the wide class of problem. But there are the calculated difficulties for the equations, which take place for nonlinear hyperbolic systems. In this connection, It is necessary to impose the additional restrictions which assure the existence and unique of solutions. As test sample, we use the free wave packet and study its behavior at the different initial and boundary conditions. The calculations of wave packet propagation cause in numerical algorithm the division. In numerical algorithm at the calculations of wave packet propagation, there arises the problem of division by zero. To overcome this problem we have to sew together discrete numerical and analytical continuous solutions on the boundary. We demonstrate here for the free wave packet that the numerical solution corresponds to the analytical solution.

  1. Hydrodynamic interactions between two vesicles

    NASA Astrophysics Data System (ADS)

    Gires, Pierre-Yves; Dyfcom Team

    2011-11-01

    A giant vesicle is a closed elastic membrane containing a liquid, inside another liquid. Its size is around 10 microns. If a suspension of such objects is sheared, they sometimes come close and interact hydrodynamically. We studied how these interactions affect the trajectories of the vesicles. For this, we model the properties of the membrane, assuming that the area of a surface element is constant in the course of time, and that it resists bending. We also assume that the inside and outside fluids are Newtonian, and are in the creeping regime. To solve the partial differential equations arising from this model, we used two methods : an asymptotic expansion around spherical shapes for vesicles far away from each other (3d case), and a boudary integral method (2d case). We find that vesicles repel, and that this repulsion decreases with initial transverse distance. We compare our results with experimental results performed with vesicles flowing in microfluidic devices.

  2. Deterministic hydrodynamics: Taking blood apart

    PubMed Central

    Davis, John A.; Inglis, David W.; Morton, Keith J.; Lawrence, David A.; Huang, Lotien R.; Chou, Stephen Y.; Sturm, James C.; Austin, Robert H.

    2006-01-01

    We show the fractionation of whole blood components and isolation of blood plasma with no dilution by using a continuous-flow deterministic array that separates blood components by their hydrodynamic size, independent of their mass. We use the technology we developed of deterministic arrays which separate white blood cells, red blood cells, and platelets from blood plasma at flow velocities of 1,000 μm/sec and volume rates up to 1 μl/min. We verified by flow cytometry that an array using focused injection removed 100% of the lymphocytes and monocytes from the main red blood cell and platelet stream. Using a second design, we demonstrated the separation of blood plasma from the blood cells (white, red, and platelets) with virtually no dilution of the plasma and no cellular contamination of the plasma. PMID:17001005

  3. The hydrodynamic theory of detonation

    NASA Technical Reports Server (NTRS)

    Langweiler, Heinz

    1939-01-01

    This report derives equations containing only directly measurable constants for the quantities involved in the hydrodynamic theory of detonation. The stable detonation speed, D, is revealed as having the lowest possible value in the case of positive material velocity, by finding the minimum of the Du curve (u denotes the speed of the gases of combustion). A study of the conditions of energy and impulse in freely suspended detonating systems leads to the disclosure of a rarefaction front traveling at a lower speed behind the detonation front; its velocity is computed. The latent energy of the explosive passes into the steadily growing detonation zone - the region between the detonation front and the rarefaction front. The conclusions lead to a new definition of the concept of shattering power. The calculations are based on the behavior of trinitrotoluene.

  4. Nonstandard Gaits in Unsteady Hydrodynamics

    NASA Astrophysics Data System (ADS)

    Fairchild, Michael; Rowley, Clarence

    2016-11-01

    Marine biology has long inspired the design and engineering of underwater vehicles. The literature examining the kinematics and dynamics of fishes, ranging from undulatory anguilliform swimmers to oscillatory ostraciiform ones, is vast. Past numerical studies of these organisms have principally focused on gaits characterized by sinusoidal pitching and heaving motions. It is conceivable that more sophisticated gaits could perform better in some respects, for example as measured by thrust generation or by cost of transport. This work uses an unsteady boundary-element method to numerically investigate the hydrodynamics and propulsive efficiency of high-Reynolds-number swimmers whose gaits are encoded by Fourier series or by Jacobi elliptic functions. Numerical results are presented with an emphasis on identifying particular wake structures and modes of motion that are associated with optimal swimming. This work was supported by the Office of Naval Research through MURI Grant N00014-14-1-0533.

  5. Stellar Explosions: Hydrodynamics and Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    Jose, Jordi

    2016-01-01

    Stars are the main factories of element production in the universe through a suite of complex and intertwined physical processes. Such stellar alchemy is driven by multiple nuclear interactions that through eons have transformed the pristine, metal-poor ashes leftover by the Big Bang into a cosmos with 100 distinct chemical species. The products of stellar nucleosynthesis frequently get mixed inside stars by convective transport or through hydrodynamic instabilities, and a fraction of them is eventually ejected into the interstellar medium, thus polluting the cosmos with gas and dust. The study of the physics of the stars and their role as nucleosynthesis factories owes much to cross-fertilization of different, somehow disconnected fields, ranging from observational astronomy, computational astrophysics, and cosmochemistry to experimental and theoretical nuclear physics. Few books have simultaneously addressed the multidisciplinary nature of this field in an engaging way suitable for students and young scientists. Providing the required multidisciplinary background in a coherent way has been the driving force for Stellar Explosions: Hydrodynamics and Nucleosynthesis. Written by a specialist in stellar astrophysics, this book presents a rigorous but accessible treatment of the physics of stellar explosions from a multidisciplinary perspective at the crossroads of computational astrophysics, observational astronomy, cosmochemistry, and nuclear physics. Basic concepts from all these different fields are applied to the study of classical and recurrent novae, type I and II supernovae, X-ray bursts and superbursts, and stellar mergers. The book shows how a multidisciplinary approach has been instrumental in our understanding of nucleosynthesis in stars, particularly during explosive events.

  6. Stellar Explosions: Hydrodynamics and Nucleosynthesis

    NASA Astrophysics Data System (ADS)

    José, Jordi

    2015-12-01

    Stars are the main factories of element production in the universe through a suite of complex and intertwined physical processes. Such stellar alchemy is driven by multiple nuclear interactions that through eons have transformed the pristine, metal-poor ashes leftover by the Big Bang into a cosmos with 100 distinct chemical species. The products of stellar nucleosynthesis frequently get mixed inside stars by convective transport or through hydrodynamic instabilities, and a fraction of them is eventually ejected into the interstellar medium, thus polluting the cosmos with gas and dust. The study of the physics of the stars and their role as nucleosynthesis factories owes much to cross-fertilization of different, somehow disconnected fields, ranging from observational astronomy, computational astrophysics, and cosmochemistry to experimental and theoretical nuclear physics. Few books have simultaneously addressed the multidisciplinary nature of this field in an engaging way suitable for students and young scientists. Providing the required multidisciplinary background in a coherent way has been the driving force for Stellar Explosions: Hydrodynamics and Nucleosynthesis. Written by a specialist in stellar astrophysics, this book presents a rigorous but accessible treatment of the physics of stellar explosions from a multidisciplinary perspective at the crossroads of computational astrophysics, observational astronomy, cosmochemistry, and nuclear physics. Basic concepts from all these different fields are applied to the study of classical and recurrent novae, type I and II supernovae, X-ray bursts and superbursts, and stellar mergers. The book shows how a multidisciplinary approach has been instrumental in our understanding of nucleosynthesis in stars, particularly during explosive events.

  7. The hydrodynamics of dolphin drafting

    PubMed Central

    Weihs, Daniel

    2004-01-01

    Background Drafting in cetaceans is defined as the transfer of forces between individuals without actual physical contact between them. This behavior has long been surmised to explain how young dolphin calves keep up with their rapidly moving mothers. It has recently been observed that a significant number of calves become permanently separated from their mothers during chases by tuna vessels. A study of the hydrodynamics of drafting, initiated in the hope of understanding the mechanisms causing the separation of mothers and calves during fishing-related activities, is reported here. Results Quantitative results are shown for the forces and moments around a pair of unequally sized dolphin-like slender bodies. These include two major effects. First, the so-called Bernoulli suction, which stems from the fact that the local pressure drops in areas of high speed, results in an attractive force between mother and calf. Second is the displacement effect, in which the motion of the mother causes the water in front to move forwards and radially outwards, and water behind the body to move forwards to replace the animal's mass. Thus, the calf can gain a 'free ride' in the forward-moving areas. Utilizing these effects, the neonate can gain up to 90% of the thrust needed to move alongside the mother at speeds of up to 2.4 m/sec. A comparison with observations of eastern spinner dolphins (Stenella longirostris) is presented, showing savings of up to 60% in the thrust that calves require if they are to keep up with their mothers. Conclusions A theoretical analysis, backed by observations of free-swimming dolphin schools, indicates that hydrodynamic interactions with mothers play an important role in enabling dolphin calves to keep up with rapidly moving adult school members. PMID:15132740

  8. Hydrodynamics of segmentally flexible macromolecules.

    PubMed

    de la Torre, J G

    1994-01-01

    Segmentally flexible macromolecules are composed of a few rigid subunits linked by joints which are more or less flexible. The dynamics in solution of this type of macromolecule present special aspects that are reviewed here. Three alternative approaches are described. One is the rigid-body treatment, which is shown to be valid for overall dynamic properties such as translational diffusion and intrinsic viscosity. Another approach is the Harvey-Wegener treatment, which is particularly suited for rotational diffusion. The simplest version of this treatment, which ignores hydrodynamic interaction (HI) effects, is found to be quite accurate when compared to a more rigorous version including HI. A third approach is the Brownian dynamics simulation that, albeit at some computational cost, might describe rigorously cases of arbitrary complexity. This technique has been used to test the approximations in the rigid-body and Harvey-Wegener treatments, thus allowing a better understanding of their validity. Brownian trajectories of simplified models such as the trumbbell and the broken rod have been simulated. The comparison of the decay rates of some correlation functions with the predictions of the two treatments leads to a general conclusion: the Harvey-Wegener treatment determines the initial rate, while the long-time behavior is dominated by the rigid-body relaxation time. As an example of application to a specific biological macromolecule, we present a simulation of an immunoglobulin molecule, showing how Brownian Dynamics can be used to predict rotational and internal dynamics. Another typical example is myosin. Literature data of hydrodynamic properties of whole myosin and the myosin rod are compared with predictions from the Harvey-Wegener and rigid-body treatments. The present situation of the problem on myosin flexibility is analyzed, and some indications are given for future experimental and simulation work.

  9. Gut Microbiota-brain Axis

    PubMed Central

    Wang, Hong-Xing; Wang, Yu-Ping

    2016-01-01

    Objective: To systematically review the updated information about the gut microbiota-brain axis. Data Sources: All articles about gut microbiota-brain axis published up to July 18, 2016, were identified through a literature search on PubMed, ScienceDirect, and Web of Science, with the keywords of “gut microbiota”, “gut-brain axis”, and “neuroscience”. Study Selection: All relevant articles on gut microbiota and gut-brain axis were included and carefully reviewed, with no limitation of study design. Results: It is well-recognized that gut microbiota affects the brain's physiological, behavioral, and cognitive functions although its precise mechanism has not yet been fully understood. Gut microbiota-brain axis may include gut microbiota and their metabolic products, enteric nervous system, sympathetic and parasympathetic branches within the autonomic nervous system, neural-immune system, neuroendocrine system, and central nervous system. Moreover, there may be five communication routes between gut microbiota and brain, including the gut-brain's neural network, neuroendocrine-hypothalamic-pituitary-adrenal axis, gut immune system, some neurotransmitters and neural regulators synthesized by gut bacteria, and barrier paths including intestinal mucosal barrier and blood-brain barrier. The microbiome is used to define the composition and functional characteristics of gut microbiota, and metagenomics is an appropriate technique to characterize gut microbiota. Conclusions: Gut microbiota-brain axis refers to a bidirectional information network between the gut microbiota and the brain, which may provide a new way to protect the brain in the near future. PMID:27647198

  10. Helical axis stellarator equilibrium model

    SciTech Connect

    Koniges, A.E.; Johnson, J.L.

    1985-02-01

    An asymptotic model is developed to study MHD equilibria in toroidal systems with a helical magnetic axis. Using a characteristic coordinate system based on the vacuum field lines, the equilibrium problem is reduced to a two-dimensional generalized partial differential equation of the Grad-Shafranov type. A stellarator-expansion free-boundary equilibrium code is modified to solve the helical-axis equations. The expansion model is used to predict the equilibrium properties of Asperators NP-3 and NP-4. Numerically determined flux surfaces, magnetic well, transform, and shear are presented. The equilibria show a toroidal Shafranov shift.

  11. Two-axis angular effector

    DOEpatents

    Vaughn, Mark R.; Robinett, III, Rush D.; Phelan, John R.; Van Zuiden, Don M.

    1997-01-21

    A new class of coplanar two-axis angular effectors. These effectors combine a two-axis rotational joint analogous to a Cardan joint with linear actuators in a manner to produce a wider range of rotational motion about both axes defined by the joint. This new class of effectors also allows design of robotic manipulators having very high strength and efficiency. These effectors are particularly suited for remote operation in unknown surroundings, because of their extraordinary versatility. An immediate application is to the problems which arise in nuclear waste remediation.

  12. Comparing prediction models for radiographic exposures

    NASA Astrophysics Data System (ADS)

    Ching, W.; Robinson, J.; McEntee, M. F.

    2015-03-01

    During radiographic exposures the milliampere-seconds (mAs), kilovoltage peak (kVp) and source-to-image distance can be adjusted for variations in patient thicknesses. Several exposure adjustment systems have been developed to assist with this selection. This study compares the accuracy of four systems to predict the required mAs for pelvic radiographs taken on a direct digital radiography system (DDR). Sixty radiographs were obtained by adjusting mAs to compensate for varying combinations of source-to-image distance (SID), kVp and patient thicknesses. The 25% rule, the DuPont Bit System and the DigiBit system were compared to determine which of these three most accurately predicted the mAs required for an increase in patient thickness. Similarly, the 15% rule, the DuPont Bit System and the DigiBit system were compared for an increase in kVp. The exposure index (EI) was used as an indication of exposure to the DDR. For each exposure combination the mAs was adjusted until an EI of 1500+/-2% was achieved. The 25% rule was the most accurate at predicting the mAs required for an increase in patient thickness, with 53% of the mAs predictions correct. The DigiBit system was the most accurate at predicting mAs needed for changes in kVp, with 33% of predictions correct. This study demonstrated that the 25% rule and DigiBit system were the most accurate predictors of mAs required for an increase in patient thickness and kVp respectively. The DigiBit system worked well in both scenarios as it is a single exposure adjustment system that considers a variety of exposure factors.

  13. Bone suppression technique for chest radiographs

    NASA Astrophysics Data System (ADS)

    Huo, Zhimin; Xu, Fan; Zhang, Jane; Zhao, Hui; Hobbs, Susan K.; Wandtke, John C.; Sykes, Anne-Marie; Paul, Narinder; Foos, David

    2014-03-01

    High-contrast bone structures are a major noise contributor in chest radiographic images. A signal of interest in a chest radiograph could be either partially or completely obscured or "overshadowed" by the highly contrasted bone structures in its surrounding. Thus, removing the bone structures, especially the posterior rib and clavicle structures, is highly desirable to increase the visibility of soft tissue density. We developed an innovative technology that offers a solution to suppress bone structures, including posterior ribs and clavicles, on conventional and portable chest X-ray images. The bone-suppression image processing technology includes five major steps: 1) lung segmentation, 2) rib and clavicle structure detection, 3) rib and clavicle edge detection, 4) rib and clavicle profile estimation, and 5) suppression based on the estimated profiles. The bone-suppression software outputs an image with both the rib and clavicle structures suppressed. The rib suppression performance was evaluated on 491 images. On average, 83.06% (±6.59%) of the rib structures on a standard chest image were suppressed based on the comparison of computer-identified rib areas against hand-drawn rib areas, which is equivalent to about an average of one rib that is still visible on a rib-suppressed image based on a visual assessment. Reader studies were performed to evaluate reader performance in detecting lung nodules and pneumothoraces with and without a bone-suppression companion view. Results from reader studies indicated that the bone-suppression technology significantly improved radiologists' performance in the detection of CT-confirmed possible nodules and pneumothoraces on chest radiographs. The results also showed that radiologists were more confident in making diagnoses regarding the presence or absence of an abnormality after rib-suppressed companion views were presented

  14. Clinical and radiographic degenerative spondylolisthesis (CARDS) classification.

    PubMed

    Kepler, Christopher K; Hilibrand, Alan S; Sayadipour, Amir; Koerner, John D; Rihn, Jeffrey A; Radcliff, Kristen E; Vaccaro, Alexander R; Albert, Todd J; Anderson, D Greg

    2015-08-01

    Lumbar degenerative spondylolisthesis (DS) is a common, acquired condition leading to disabling back and/or leg pain. Although surgery is common used to treat patients with severe symptoms, there are no universally accepted treatment guidelines. Wide variation in vertebral translation, disc collapse, sagittal alignment, and vertebral mobility suggests this is a heterogeneous disease. A classification scheme would be useful to differentiate homogenous subgroups that may benefit from different treatment strategies. To develop and test the reliability of a simple, clinically useful classification scheme for lumbar DS. Retrospective case series. One hundred twenty-six patients. Proposed radiographic classification system. A classification system is proposed that considers disc space height, sagittal alignment and translation, and the absence or presence of unilateral or bilateral leg pain. Test cases were graded by six observers to establish interobserver reliability and regraded in a different order 1 month later to establish intraobserver reliability using Kappa analysis. To establish the relative prevalence of each subtype, a series of 100 consecutive patients presenting with L4-L5 DS were classified. Four radiographic subtypes were identified: Type A: advanced Disc space collapse without kyphosis; Type B: disc partially preserved with translation of 5 mm or less; Type C: disc partially preserved with translation of more than 5 mm; and Type D: kyphotic alignment. The leg pain modifier 0 denotes no leg pain, 1 denotes unilateral leg pain, and 2 represents bilateral leg pain. The Kappa value describing interobserver reliability was 0.82, representing near-perfect agreement. Intraobserver reliability analysis demonstrated Kappa=0.83, representing near-perfect agreement. Grading of the consecutive series of 100 patients revealed the following distribution: 16% Type A, 37% Type B, 33% Type C, and 14% Type D. A new radiographic and clinical classification scheme for

  15. Segmentation of ribs in digital chest radiographs

    NASA Astrophysics Data System (ADS)

    Cong, Lin; Guo, Wei; Li, Qiang

    2016-03-01

    Ribs and clavicles in posterior-anterior (PA) digital chest radiographs often overlap with lung abnormalities such as nodules, and cause missing of these abnormalities, it is therefore necessary to remove or reduce the ribs in chest radiographs. The purpose of this study was to develop a fully automated algorithm to segment ribs within lung area in digital radiography (DR) for removal of the ribs. The rib segmentation algorithm consists of three steps. Firstly, a radiograph was pre-processed for contrast adjustment and noise removal; second, generalized Hough transform was employed to localize the lower boundary of the ribs. In the third step, a novel bilateral dynamic programming algorithm was used to accurately segment the upper and lower boundaries of ribs simultaneously. The width of the ribs and the smoothness of the rib boundaries were incorporated in the cost function of the bilateral dynamic programming for obtaining consistent results for the upper and lower boundaries. Our database consisted of 93 DR images, including, respectively, 23 and 70 images acquired with a DR system from Shanghai United-Imaging Healthcare Co. and from GE Healthcare Co. The rib localization algorithm achieved a sensitivity of 98.2% with 0.1 false positives per image. The accuracy of the detected ribs was further evaluated subjectively in 3 levels: "1", good; "2", acceptable; "3", poor. The percentages of good, acceptable, and poor segmentation results were 91.1%, 7.2%, and 1.7%, respectively. Our algorithm can obtain good segmentation results for ribs in chest radiography and would be useful for rib reduction in our future study.

  16. Mesiodens: a radiographic study in children.

    PubMed

    Gündüz, Kaan; Celenk, Peruze; Zengin, Zeynep; Sümer, Pinar

    2008-09-01

    We analyzed the frequency and radiological features of mesiodens in a group of children in Turkey. The study was based on a radiographic review of 23,000 pediatric patients (male: 12,667 female; 10,333) who visited the Department of Oral Diagnosis and Radiology during the period 2003-2005 (3 years). The presence of an unerupted supernumerary tooth, or tooth bud between the 2 central incisors or as unilateral or bilateral teeth in the midline of the maxilla was noted as mesiodens on radiographs. Eighty-five cases of mesiodens in 69 patients were found. Complete documentation, including radiographs, for these 69 patients were studied and analyzed. In addition to gender and age, the following information about the mesiodens was recorded: 1) number; 2) shape; 3) position; 4) complications caused by the mesiodens; 5) treatment. Of the 69 patients, the ratio of boys (47 cases) to girls (22 cases) was 2.1:1. Fifty-three (76.8%) of the children had 1 mesiodens, and 16 (23.1%) had 2 mesiodentes bilaterally to the midline. Of the 85 mesiodentes, 67 (78.8%) were fully impacted, 6 (7%) were partially erupted, and 12 (14.1%) were fully erupted. Most of the mesiodentes (55.2%) were found in the vertical position, followed by inverted position (37.6%), and horizontal position (7%). The main complications were delayed eruption of the permanent incisors (38.8%), maxillary midline diastema (17.6%), axial rotation or inclination of erupted permanent incisors (16.4%), and resorption of the adjacent teeth (4.7%) The prevelance of mesiodens has been estimated to be 0.15% to 2.2% of the population.

  17. Radiographic Evaluation of Common Pediatric Elbow Injuries

    PubMed Central

    DeFroda, Steven F.; Hansen, Heather; Gil, Joseph A.; Hawari, Ashraf H.; Cruz, Aristides I.

    2017-01-01

    Normal variations in anatomy in the skeletally immature patient may be mistaken for fracture or injury due to the presence of secondary centers of ossification. Variations in imaging exist from patient to patient based on sex, age, and may even vary from one extremity to the other on the same patient. Despite differences in the appearance of the bony anatomy of the elbow there are certain landmarks and relationships, which can help, distinguish normal from abnormal. We review common radiographic parameters and pitfalls associated in the evaluation of pediatric elbow imaging. We also review common clinical diagnoses in this population. PMID:28286625

  18. Chest radiographic manifestations of scrub typhus

    PubMed Central

    Abhilash, KPP; Mannam, PR; Rajendran, K; John, RA; Ramasami, P

    2016-01-01

    Background and Rationale: Respiratory system involvement in scrub typhus is seen in 20–72% of patients. In endemic areas, good understanding and familiarity with the various radiologic findings of scrub typhus are essential in identifying pulmonary complications. Materials and Methods: Patients admitted to a tertiary care center with scrub typhus between October 2012 and September 2013 and had a chest X ray done were included in the analysis. Details and radiographic findings were noted and factors associated with abnormal X-rays were analyzed. Results: The study cohort contained 398 patients. Common presenting complaints included fever (100%), generalized myalgia (83%), headache (65%), dyspnea (54%), cough (24.3%), and altered sensorium (14%). Almost half of the patients (49.4%) had normal chest radiographs. Common radiological pulmonary abnormalities included pleural effusion (14.6%), acute respiratory distress syndrome (14%), airspace opacity (10.5%), reticulonodular opacities (10.3%), peribronchial thickening (5.8%), and pulmonary edema (2%). Cardiomegaly was noted in 3.5% of patients. Breathlessness, presence of an eschar, platelet counts of <20,000 cells/cumm, and total serum bilirubin >2 mg/dL had the highest odds of having an abnormal chest radiograph. Patients with an abnormal chest X-ray had a higher requirement of noninvasive ventilation (odds ratio [OR]: 13.98; 95% confidence interval CI: 5.89–33.16), invasive ventilation (OR: 18.07; 95% CI: 6.42–50.88), inotropes (OR: 8.76; 95% CI: 4.35–17.62), higher involvement of other organ systems, longer duration of hospital stay (3.18 ± 3 vs. 7.27 ± 5.58 days; P < 0.001), and higher mortality (OR: 4.63; 95% CI: 1.54–13.85). Conclusion: Almost half of the patients with scrub typhus have abnormal chest radiographs. Chest radiography should be included as part of basic evaluation at presentation in patients with scrub typhus, especially in those with breathlessness, eschar, jaundice, and severe

  19. Inspecting Pipe Radiographically Through Asbestos Insulation

    NASA Technical Reports Server (NTRS)

    Gianettino, David P.

    1994-01-01

    Welds between sections of insulated steampipe located and inspected radiographically. Unless need to repair defective weld, one avoids cost, time, and hazard of removing asbestos insulation. Enables inspectors to locate and evaluate nondestructively any weld in pipe system, without shutting down steam. Hidden weld joints first located by use of low-power fluoroscope, moved along pipe while technician observes fluoroscopic image. Low-energy x rays from fluoroscope penetrate insulation but not pipe. Weld bead appears in silhouette on fluoroscope screen. Technician then accurately marks weld sites on insulation for later inspection.

  20. Inspecting Pipe Radiographically Through Asbestos Insulation

    NASA Technical Reports Server (NTRS)

    Gianettino, David P.

    1994-01-01

    Welds between sections of insulated steampipe located and inspected radiographically. Unless need to repair defective weld, one avoids cost, time, and hazard of removing asbestos insulation. Enables inspectors to locate and evaluate nondestructively any weld in pipe system, without shutting down steam. Hidden weld joints first located by use of low-power fluoroscope, moved along pipe while technician observes fluoroscopic image. Low-energy x rays from fluoroscope penetrate insulation but not pipe. Weld bead appears in silhouette on fluoroscope screen. Technician then accurately marks weld sites on insulation for later inspection.

  1. [Detection method for blurred regions in radiographs].

    PubMed

    Muroi, Tomoya; Lee, Yongbum; Tsai, Du-Yih; Tsurumaki, Masaki

    2014-03-01

    In this paper, we propose a detection method for blurred regions in radiographs. The method involves edge detection using a Sobel filter, manually determining the region of interest (ROI), feature calculation, and classification using a support vector machine. We applied our method to 14 phantom images (7 normal images, 7 blurred images) and 14 clinical images (12 normal images, 2 blurred images). As a result, the average classification accuracies of ROIs with blurring and ROIs without blurring were 98% and 90% for phantom images and clinical images, respectively.

  2. Endocrine changes in histiocytosis of the hypothalamic-pituitary axis.

    PubMed

    Toro Galván, Silvia; Planas Vilaseca, Alejandra; Michalopoulou Alevras, Theodora; Torres Díaz, Alberto; Suárez Balaguer, Javier; Villabona Artero, Carles

    2015-02-01

    Histiocytosis is characterized by proliferation of cells from the mononuclear phagocyte system, and may be divided into Langerhans cell histiocytosis (LCH) and non-Langerhans cell histiocytosis (including Erdheim-Chester disease [ECD]). While diabetes insipidus (DI) is the most common hypothalamic-pituitary consequence, anterior pituitary deficiencies are less known. This study analyzed the frequency and progression of pituitary hormone deficiencies and the radiographic findings in 9 patients (7 with LCH and 2 with ECD) with hypothalamic-pituitary (HP) axis. Eighty-nine percent of patients had DI (62% at diagnosis), and 78% had one or more anterior pituitary deficiencies (71% at diagnosis). HP involvement is relatively common in patients diagnosed with histiocytosis and hormone deficiencies may be present at diagnosis or appear gradually during the course of disease. Regular monitoring of these patients is recommended. Copyright © 2014 SEEN. Published by Elsevier España, S.L.U. All rights reserved.

  3. Radiographic studies and hydrocode simulations of two tantalum EFPs (explosively formed penetrators)

    SciTech Connect

    Schwalbe, L.A.

    1988-01-01

    The Army Research Development and Engineering Center (ARDEC) commissioned Los Alamos to provide Honeywell, Inc. with one high- energy flash radiograph for each of two explosively formed penetrators (EFPs) of tantalum. The two axisymmetric warheads were identical in their basic design, but their liner contours were different. The first shot, which we designate as H853, used Honeywell's liner design /number sign/1; the second shot, H854, used design /number sign/2. The experiments were planned and directed by J. M. Christian (M-4) and were performed at the Ector radiographic facility (R-306) during the weak of February 22, 1988. Data reduction and analyses were accomplished over the next several months by K. H. Mueller, Jr. (M-4) and L. A. Schwalbe (X-3). In addition to the experimental work, the computations group (X-3) offered to run hydrodynamic code simulations of the EFP formation for the two designs. Some of the results and conclusions of this theoretical work are also presented below. 5 refs., 7 figs.

  4. Quality assurance: a comparison study of radiographic exposure for neonatal chest radiographs at 4 academic hospitals.

    PubMed

    Cohen, Mervyn D; Markowitz, Richard; Hill, Jeanne; Huda, Walter; Babyn, Paul; Apgar, Bruce

    2012-06-01

    Little is known about exposure differences among hospitals. Large differences might identify outliers using excessive exposure. We used the newly described exposure index and deviation index to compare the difference in existing radiographic exposures for neonatal portable chest radiographs among four academic children's hospitals. For each hospital we determined the mean exposure index. We also set target exposure indices and then measured the deviation from this target. There was not a large difference in exposure index among sites. No site had an exposure index mean that was more than twice or less than half that of any other site. For all four sites combined, 92% of exposures had a deviation index within the range from -3 to +3. Thus exposures at each hospital were consistently within a reasonable narrow spectrum. Mean exposure index differences are caused by operational differences with mean values that varied by less than 50% among four hospitals. Ninety-two percent of all exposures were between half and double the target exposure. Although only one vendor's equipment was used, these data establish a practical reference range of exposures for neonatal portable radiographs that can be recommended to other hospitals for neonatal chest radiographs.

  5. Anatomical study of the gastrointestinal tract in free-living axis deer (Axis axis).

    PubMed

    Pérez, W; Erdogan, S; Ungerfeld, R

    2015-02-01

    The macroscopic anatomy of the stomach and intestines of adult axis deer (Axis axis), a cervid species considered intermediate/mixed feeder, was observed and recorded. Nine adult wild axis deers of both sexes were used and studied by simple dissection. The ruminal papillae were distributed unevenly in the overall area of the inner surface of rumen and primarily were more large and abundant within the atrium. The ruminal pillars had no papillae. There was an additional ruminal pillar located between the right longitudinal and right coronary ventral pillars connected to the caudal pillar. No dorsal coronary pillars were found, and the ventral coronary pillars are connected. The reticulum was the third compartment in size, and the maximum height of the reticular crests was 1.0 mm. The Cellulae reticuli were not divided and rarely contained secondary crests. There were no Papillae unguiculiformes. The omasum was the smallest gastric compartment. The abomasum had about twelve spiral plicae, and a small pyloric torus was present. The intraruminal papillation was similar to those species that are characterized by a higher proportion of grass in their natural diet. The finding of the small reticular crests is typical for browser ruminants and was coincident with data reported for other deer. The comparative ratio of the small intestine to the large intestine was 1.69, in terms of length measurements in axis deer and appears below of the 'browser range'. We concluded that the gastrointestinal system of axis deer reflected similar morphological characteristics of the both types of ruminants: browser and grazer, and we consider it as an intermediate feeder. © 2014 Blackwell Verlag GmbH.

  6. Multi-Axis Test Facility

    NASA Image and Video Library

    1959-11-01

    Multi-Axis Test Facility, Space Progress Report, November 1, 1959: The Multi Axis Space Test Inertia Facility [MASTIF], informally referred to as the Gimbal Rig, was installed inside the Altitude Wind Tunnel. The rig, which spun on three axis simultaneously, was used to train the Mercury astronauts on how to bring a spinning spacecraft under control and to determine the effects of rapid spinning on the astronaut's eyesight and psyche. Small gaseous nitrogen jets were operated by the pilot to gain control of the rig after it had been set in motion. Part 1 shows pilot Joe Algranti in the rig as it rotates over one, two, and three axis. It also has overall views of the test set-up with researchers and technicians on the test platform. Part 2 shows Algranti being secured in the rig prior to the test. The rig is set in motion and the pilot slowly brings it under control. The Mercury astronauts trained on the MASTIF in early spring of 1960.

  7. Three axis velocity probe system

    DOEpatents

    Fasching, George E.; Smith, Jr., Nelson S.; Utt, Carroll E.

    1992-01-01

    A three-axis velocity probe system for determining three-axis positional velocities of small particles in fluidized bed systems and similar applications. This system has a sensor head containing four closely-spaced sensing electrodes of small wires that have flat ends to establish a two axis plane, e.g. a X-Y plane. Two of the sensing electrodes are positioned along one of the axes and the other two are along the second axis. These four sensing electrodes are surrounded by a guard electrode, and the outer surface is a ground electrode and support member for the sensing head. The electrodes are excited by, for example, sinusoidal voltage having a peak-to-peak voltage of up to 500 volts at a frequency of 2 MHz. Capacitive currents flowing between the four sensing electrodes and the ground electrode are influenced by the presence and position of a particle passing the sensing head. Any changes in these currents due to the particle are amplified and synchronously detected to produce positional signal values that are converted to digital form. Using these digital forms and two values of time permit generation of values of the three components of the particle vector and thus the total velocity vector.

  8. Structural damage in rheumatoid arthritis as visualized through radiographs

    PubMed Central

    2002-01-01

    Several agents show an effect on reducing radiographic progression in rheumatoid arthritis. It is tempting to retrospectively compare the effects of these agents on radiographic progression across clinical trials. However, there are several limitations in interpreting and comparing radiographic results across clinical trials. These limitations, including study designs, patient characteristics, durations of follow-up, scoring methodologies, reader reliability, radiograph sequence, handling of missing data, and data presentation, will be discussed. The consequences are illustrated with several examples of recent clinical trials that show an effect on radiographic progression. A guide in the interpretation and clinical relevance of radiographic results is presented, with the Anti-TNF Trial in Rheumatoid Arthritis with Concomitant Therapy used as an example. PMID:12110155

  9. MRI visualisation by digitally reconstructed radiographs

    NASA Astrophysics Data System (ADS)

    Serrurier, Antoine; Bönsch, Andrea; Lau, Robert; Deserno, Thomas M.

    2015-03-01

    Visualising volumetric medical images such as computed tomography and magnetic resonance imaging (MRI) on picture archiving and communication systems (PACS) clients is often achieved by image browsing in sagittal, coronal or axial views or three-dimensional (3D) rendering. This latter technique requires fine thresholding for MRI. On the other hand, computing virtual radiograph images, also referred to as digitally reconstructed radiographs (DRR), provides in a single two-dimensional (2D) image a complete overview of the 3D data. It appears therefore as a powerful alternative for MRI visualisation and preview in PACS. This study describes a method to compute DRR from T1-weighted MRI. After segmentation of the background, a histogram distribution analysis is performed and each foreground MRI voxel is labeled as one of three tissues: cortical bone, also known as principal absorber of the X-rays, muscle and fat. An intensity level is attributed to each voxel according to the Hounsfield scale, linearly related to the X-ray attenuation coefficient. Each DRR pixel is computed as the accumulation of the new intensities of the MRI dataset along the corresponding X-ray. The method has been tested on 16 T1-weighted MRI sets. Anterior-posterior and lateral DRR have been computed with reasonable qualities and avoiding any manual tissue segmentations. This proof-of-concept holds for research application for use in clinical PACS.

  10. Age estimation by using dental radiographs

    PubMed Central

    Limdiwala, Piyush G.; Shah, J. S.

    2013-01-01

    Background: Estimation of age is important in forensic sciences as a way to establish the identity of human remains. Of the various parts of the body used in age estimation, teeth are the least affected by the taphonomic process. Their durability means that they are sometimes the only body part available for study. Several methods of age estimation have been studied using bone and teeth, and among them, tooth wear and apposition of secondary dentine are the currently available non-destructive methods. Objectives: The purpose of the study was to determine the age of adults by using Kvaal's method as well as to establish the relationship of chronological age and dental age with its reliability and limitations on digital panoramic radiographs. Materials and Methods: The present study was based on panoramic radiographs that consisted of two groups. One hundred orthopantomographs with Kvaal's criteria (Group A) and 50 orthopantomographs without Kvaal's criteria (Group B) were included. Various parameters were measured and the result was analyzed by means of SPSS-12.0 program statistical data. Result and Conclusion: On the basis of Kvaal's criteria, the difference between chronological age and real age was 8.3 years. This suggests that the accuracy of this method depends on the precision of measurements and quality and number of the orthopantomographs. PMID:24255560

  11. Tooth ankylosis. Clinical, radiographic and histological assessments.

    PubMed

    Andersson, L; Blomlöf, L; Lindskog, S; Feiglin, B; Hammarström, L

    1984-10-01

    Ankylosis is a serious condition for the affected teeth as such teeth form part of the remodelling process of the alveolar bone and are therefore progressively resorbed. There are, however, very few clinical studies on tooth ankylosis and the reason for this may be due to the difficulties that are encountered in the diagnosis of minor areas of ankylosis. In the present study, the radiographs, percussion sound and mobility of experimentally extracted and replanted monkey incisors were compared with a morphometric histological study of ankylosis. Ankylotic areas were evident radiographically when the ankylosis was located on the proximal surfaces of the root, but were not evident when the ankylosis occurred on the lingual and labial surfaces. The percussion sound was dull and the mobility normal in all non-ankylotic teeth as well as in those teeth which histologically demonstrated ankylosis on less than 10% of the root surface. When the ankylosis affected 10-20% of the root surface, 2 out of 4 teeth changed their percussion sound from dull to high and these teeth no longer possessed normal mobility. When more than 20% of the root surface was affected with ankylosis, the percussion sound was characteristically high in all teeth and no mobility was present.

  12. Radiographic X-Ray Pulse Jitter

    SciTech Connect

    Mitton, C. V., Good, D. E., Henderson, D. J., Hogge, K. W.

    2011-01-15

    The Dual Beam Radiographic Facility consists of two identical radiographic sources. Major components of the machines are: Marx generator, water-filled pulse-forming line (PFL), water-filled coaxial transmission line, three-cell inductive voltage adder, and rod-pinch diode. The diode pulse has the following electrical specifications: 2.25-MV, 60-kA, 60-ns. Each source has the following x-ray parameters: 1-mm-diameter spot size, 4-rad at 1 m, 50-ns full width half max. The x-ray pulse is measured with PIN diode detectors. The sources were developed to produce high resolution images on single-shot, high-value experiments. For this application it is desirable to maintain a high level of reproducibility in source output. X-ray pulse jitter is a key metric for analysis of reproducibility. We will give measurements of x-ray jitter for each machine. It is expected that x-ray pulse jitter is predominantly due to PFL switch jitter, and therefore a correlation of the two will be discussed.

  13. Mass flux in extended and classical hydrodynamics.

    PubMed

    Grmela, Miroslav

    2014-06-01

    In classical hydrodynamics, the mass flux is universally chosen to be the momentum field. In extended hydrodynamics, the mass flux acquires different terms. The extended hydrodynamics introduced and investigated in this paper uses a one-particle distribution function as the extra state variable chosen to characterize the microstructure. We prove that the extended hydrodynamics is fully autonomous in the sense that it is compatible with thermodynamics (i.e., the entropy does not decrease during the time evolution) and with mechanics (i.e., the part of the time evolution that leaves the entropy unchanged is Hamiltonian). Subsequently, we investigate its possible reductions. In some situations the emerging reduced dynamical theory is the classical hydrodynamics that is fully autonomous (i.e., all the structure that makes the extended theory fully autonomous is kept in the reduced theory). In other situations (for example, when the fluids under investigation have large density gradients) the reduced theories are not fully autonomous. In such a case the reduced theories constitute a family of mutually related dynamical theories (each of them involving a different amount of detail) that we consider to be a mathematical formulation of multiscale (or multilevel) hydrodynamics. It is in the reduced theories belonging to the multiscale hydrodynamics where the terms that emerge in the mass flux take the form of self-diffusion.

  14. Fetal and Neonatal HPA Axis.

    PubMed

    Wood, Charles E; Walker, Claire-Dominique

    2015-12-15

    Stress is an integral part of life. Activation of the hypothalamus-pituitary-adrenal (HPA) axis in the adult can be viewed as mostly adaptive to restore homeostasis in the short term. When stress occurs during development, and specifically during periods of vulnerability in maturing systems, it can significantly reprogram function, leading to pathologies in the adult. Thus, it is critical to understand how the HPA axis is regulated during developmental periods and what are the factors contributing to shape its activity and reactivity to environmental stressors. The HPA axis is not a passive system. It can actively participate in critical physiological regulation, inducing parturition in the sheep for instance or being a center stage actor in the preparation of the fetus to aerobic life (lung maturation). It is also a major player in orchestrating mental function, metabolic, and cardiovascular function often reprogrammed by stressors even prior to conception through epigenetic modifications of gametes. In this review, we review the ontogeny of the HPA axis with an emphasis on two species that have been widely studied-sheep and rodents-because they each share many similar regulatory mechanism applicable to our understanding of the human HPA axis. The studies discussed in this review should ultimately inform us about windows of susceptibility in the developing brain and the crucial importance of early preconception, prenatal, and postnatal interventions designed to improve parental competence and offspring outcome. Only through informed studies will our public health system be able to curb the expansion of many stress-related or stress-induced pathologies and forge a better future for upcoming generations.

  15. Explicit 3D continuum fracture modeling with smooth particle hydrodynamics

    NASA Technical Reports Server (NTRS)

    Benz, W.; Asphaug, E.

    1993-01-01

    Impact phenomena shaped our solar system. As usual for most solar system processes, the scales are far different than we can address directly in the laboratory. Impact velocities are often much higher than we can achieve, sizes are often vastly larger, and most impacts take place in an environment where the only gravitational force is the mutual pull of the impactors. The Smooth Particle Hydrodynamics (SPH) technique has been applied in the past to the simulations of giant impacts. In these simulations, the colliding objects were so massive (at least a sizeable fraction of the Earth's mass) that material strength was negligible compared to gravity. This assumption can no longer be made when the bodies are much smaller. To this end, we have developed a 3D SPH code that includes a strength model to which we have added a von Mises yielding relation for stresses beyond the Hugoniot Elastic Limit. At the lower stresses associated with brittle failure, we use a rate-dependent strength based on the nucleation of incipient flaws whose number density is given by a Weibull distribution. Following Grady and Kipp and Melosh et al., we introduce a state variable D ('damage'), 0 less than D less than 1, which expresses the local reduction in strength due to crack growth under tensile loading. Unfortunately for the hydrodynamics, Grady and Kipp's model predicts which fragments are the most probable ones and not the ones that are really formed. This means, for example, that if a given laboratory experiment is modeled, the fragment distribution obtained from the Grady-Kipp theory would be equivalent to a ensemble average over many realizations of the experiment. On the other hand, the hydrodynamics itself is explicit and evolves not an ensemble average but very specific fragments. Hence, there is a clear incompatibility with the deterministic nature of the hydrodynamics equations and the statistical approach of the Grady-Kipp dynamical fracture model. We remedy these shortcomings

  16. Explicit 3D continuum fracture modeling with smooth particle hydrodynamics

    NASA Technical Reports Server (NTRS)

    Benz, W.; Asphaug, E.

    1993-01-01

    Impact phenomena shaped our solar system. As usual for most solar system processes, the scales are far different than we can address directly in the laboratory. Impact velocities are often much higher than we can achieve, sizes are often vastly larger, and most impacts take place in an environment where the only gravitational force is the mutual pull of the impactors. The Smooth Particle Hydrodynamics (SPH) technique has been applied in the past to the simulations of giant impacts. In these simulations, the colliding objects were so massive (at least a sizeable fraction of the Earth's mass) that material strength was negligible compared to gravity. This assumption can no longer be made when the bodies are much smaller. To this end, we have developed a 3D SPH code that includes a strength model to which we have added a von Mises yielding relation for stresses beyond the Hugoniot Elastic Limit. At the lower stresses associated with brittle failure, we use a rate-dependent strength based on the nucleation of incipient flaws whose number density is given by a Weibull distribution. Following Grady and Kipp and Melosh et al., we introduce a state variable D ('damage'), 0 less than D less than 1, which expresses the local reduction in strength due to crack growth under tensile loading. Unfortunately for the hydrodynamics, Grady and Kipp's model predicts which fragments are the most probable ones and not the ones that are really formed. This means, for example, that if a given laboratory experiment is modeled, the fragment distribution obtained from the Grady-Kipp theory would be equivalent to a ensemble average over many realizations of the experiment. On the other hand, the hydrodynamics itself is explicit and evolves not an ensemble average but very specific fragments. Hence, there is a clear incompatibility with the deterministic nature of the hydrodynamics equations and the statistical approach of the Grady-Kipp dynamical fracture model. We remedy these shortcomings

  17. Substructures in hydrodynamical cluster simulations

    NASA Astrophysics Data System (ADS)

    Dolag, K.; Borgani, S.; Murante, G.; Springel, V.

    2009-10-01

    The abundance and structure of dark matter subhaloes have been analysed extensively in recent studies of dark-matter-only simulations, but comparatively little is known about the impact of baryonic physics on halo substructures. We here extend the SUBFIND algorithm for substructure identification such that it can be reliably applied to dissipative hydrodynamical simulations that include star formation. This allows, in particular, the identification of galaxies as substructures in simulations of clusters of galaxies and a determination of their content of gravitationally bound stars, dark matter and hot and cold gas. Using a large set of cosmological cluster simulations, we present a detailed analysis of halo substructures in hydrodynamical simulations of galaxy clusters, focusing in particular on the influence both of radiative and non-radiative gas physics and of non-standard physics such as thermal conduction and feedback by galactic outflows. We also examine the impact of numerical nuisance parameters such as artificial viscosity parameterizations. We find that diffuse hot gas is efficiently stripped from subhaloes when they enter the highly pressurized cluster atmosphere. This has the effect of decreasing the subhalo mass function relative to a corresponding dark-matter-only simulation. These effects are mitigated in radiative runs, where baryons condense in the central subhalo regions and form compact stellar cores. However, in all cases, only a very small fraction, of the order of one per cent, of subhaloes within the cluster virial radii preserve a gravitationally bound hot gaseous atmosphere. The fraction of mass contributed by gas in subhaloes is found to increase with the cluster-centric distance. Interestingly, this trend extends well beyond the virial radii, thus showing that galaxies feel the environment of the pressurized cluster gas over fairly large distances. The compact stellar cores (i.e. galaxies) are generally more resistant against tidal

  18. Simulating hydrodynamics on tidal mudflats

    NASA Astrophysics Data System (ADS)

    Cook, S.; Lippmann, T. C.

    2014-12-01

    Biogeochemical cycling in estuaries is governed by fluxes from both riverine sources and through estuarine sediment deposits. Although estimates from river sources are relatively common and easily sampled, estimates of nutrient fluxes through the fluid-sediment interface are less common and limited to deeper portions of the bays away from intertidal areas. Lack of quantifiable shear stress estimates over intertidal areas limits our overall understanding of nutrient budgets in estuaries. Unfortunately, observation of intertidal hydrodynamics and nutrient fluxes over tidal flats and near the water's edge is difficult owing to the temporally varying and spatially extensive region where the tides inundate, and thus numerical modeling is often employed. In this work, the Regional Ocean Modeling System (ROMS), a three dimensional numerical hydrodynamic model was used to investigate the shear stresses over intertidal mudflats in the Great Bay, a tidally-dominated New England estuary cut by several tidal channels and with over 50% of the estuary exposed at low tide. The ROMS wetting and drying scheme was used to simulate the rising and falling tide on the flats, a successful approach adapted in other regions of the world but not always inclusive of tidal channels. Bathymetric data obtained in 2009 and 2013 was used to define the model grid. Predicted tides are forced at Adam's Pt., a natural constriction in the estuary about 20 km upstream of the mouth and at the entrance to the Great Bay. Of particular interest are fluxes of material on-to and off-of the tidal flats which contribute to water quality conditions in the estuary, and are largely governed by shear stresses that drive nutrient fluxes at the fluid-sediment interface. Basin wide estimates of near-bottom shear stresses can be used to estimate first order nutrient fluxes over a tidal cycle and hence describe general biogeochemical dynamics of the estuary. Future work will include enhanced forcing of currents by

  19. Non abelian hydrodynamics and heavy ion collisions

    SciTech Connect

    Calzetta, E.

    2014-01-14

    The goal of the relativistic heavy ion collisions (RHIC) program is to create a state of matter where color degrees of freedom are deconfined. The dynamics of matter in this state, in spite of the complexities of quantum chromodynamics, is largely determined by the conservation laws of energy momentum and color currents. Therefore it is possible to describe its main features in hydrodynamic terms, the very short color neutralization time notwithstanding. In this lecture we shall give a simple derivation of the hydrodynamics of a color charged fluid, by generalizing the usual derivation of hydrodynamics from kinetic theory to the non abelian case.

  20. Tuning bacterial hydrodynamics with magnetic fields

    NASA Astrophysics Data System (ADS)

    Pierce, C. J.; Mumper, E.; Brown, E. E.; Brangham, J. T.; Lower, B. H.; Lower, S. K.; Yang, F. Y.; Sooryakumar, R.

    2017-06-01

    Magnetotactic bacteria are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nanoparticles called magnetosomes. This study exploits their innate magnetism to investigate previously unexplored facets of bacterial hydrodynamics at surfaces. Through use of weak, uniform, external magnetic fields and local, micromagnetic surface patterns, the relative strength of hydrodynamic, magnetic, and flagellar force components is tuned through magnetic control of the bacteria's orientation. The resulting swimming behaviors provide a means to experimentally determine hydrodynamic parameters and offer a high degree of control over large numbers of living microscopic entities. The implications of this controlled motion for studies of bacterial motility near surfaces and for micro- and nanotechnology are discussed.

  1. A Displayer of Stellar Hydrodynamics Processes

    NASA Astrophysics Data System (ADS)

    Vigo, José Antonio Escartín; Senz, Domingo García

    The graphics display tool that we present here was originally developed to meet the needs of the Astronomy and Astrophysics group at the UPC (GAA). At present, it is used to display the plots obtained from hydrodynamic simulations using the SPH (smoothed particle hydrodynamics) method. It is, however, a generic program that can be used for other multidimensional hydrodynamic methods. The application combines the most widely used features of other programs (most of them commercial) such as GnuPlot, Surfer, Grapher, IDL, Voxler, etc.

  2. Radiographic evaluation of occlusal caries: effect of training and experience.

    PubMed

    Lazarchik, D A; Firestone, A R; Heaven, T J; Filler, S J; Lussi, A

    1995-01-01

    The purpose of this study was to investigate what effect differing levels of didactic education and clinical experience have on the ability to diagnose occlusal caries from radiographs. Freshman and senior dental students and dental school faculty were asked to evaluate bitewing radiographs for the presence of occlusal caries and for a recommendation for restorative treatment. The agreement between histologic and radiographic diagnosis was assessed by calculating sensitivity, specificity, accuracy, and interexaminer agreement. It was concluded that dental students and faculty did differ in their abilities to evaluate radiographs for occlusal caries, and that education and clinical experience especially affected interexaminer agreement.

  3. Modified axillary radiograph of the shoulder: a new position.

    PubMed

    Senna, Luís Filipe; Pires E Albuquerque, Rodrigo

    2017-01-01

    Obtaining axillary radiographs of the shoulder in acute trauma is not always feasible. The authors present a new modification of this radiographic view, in order to assess the anatomic relationship between the humeral head and the glenoid cavity. The incidence is performed with the patient sitting on X-ray table, with the affected limb supported thereon. The authors describe the case of a 28-year-old male who suffered an anterior glenohumeral dislocation that was clearly evidenced by this modified radiograph. The concentric relationship between the humeral head and the glenoid cavity was also easily confirmed by obtaining such radiograph after the reduction maneuver.

  4. Susuk - black magic exposed "white" by dental radiographs.

    PubMed

    F, Arishiya Thapasum; Mohammed, Faraz

    2014-07-01

    Susuk or charm needles are a facial cum body art widely practiced among women of Malaysia, Brunei, Singapore, Thailand and Indonesia. These are small, needle-shaped metallic talismans inserted subcutaneously in different parts of the body. The concealed art of susuk was "exposed" by routine radiographic examination in the oral and maxillofacial region. This paper reports two such cases of unusual incidental radiographic finding in dental radiographs which were taken on a routine basis as part of the diagnostic work up. This article will also primarily enlighten the importance of radiographs in detecting such charm needles as the wearer keeps the body art a "hidden secret" thereby avoiding misdiagnosis.

  5. Stress and the Reproductive Axis

    PubMed Central

    Toufexis, Donna; Rivarola, Maria Angelica; Lara, Hernan; Viau, Victor

    2014-01-01

    There exists a reciprocal relationship between the hypothalamic-pituitary-adrenal (HPA) and the hypothalamic-pituitary-gonadal (HPG) axes wherein the activation of one affects the function of the other and vice versa. For instance, both testosterone and oestrogen modulate the response of the HPA axis, while activation of the stress axis, especially activation that is repeating or chronic, has an inhibitory effect upon oestrogen and testosterone secretion. Alterations in maternal care can produce significant effects on both HPG and HPA physiology and behaviour in the offspring at adulthood. For example, changes in reproductive behaviour induced by altered maternal care may alter the expression of sex hormone receptors like ERα that govern sexual behaviour, and may be particularly important in determining the sexual strategies utilized by females. Stress in adulthood continues to mediate HPG activity in females through activation of a sympathetic neural pathway originating in the hypothalamus and releasing norepinephrine (NE) into the ovary, which produces a non-cyclic anovulatory ovary that develops cysts. In the opposite direction, sex differences and sex steroid hormones regulate the HPA axis. For example, although serotonin (5-HT) has a stimulatory effect on the HPA axis in humans and rodents that is mediated by the 5-HT1A receptor, only male rodents respond to 5-HT1A antagonism to show increased corticosterone responses to stress. Furthermore, oestrogen appears to decrease 5-HT1A receptor function at presynaptic sites, yet increase 5-HT1A receptor expression at postsynaptic sites. These mechanisms could explain heightened stress HPA axis responses in females compared to males. Studies on female rhesus macaques show that chronic stress in socially subordinate female monkeys produces a distinct behavioral phenotype that is largely unaffected by oestrogen, a hypo-responsive HPA axis that is hypersensitive to the modulating effects of oestrogen, and changes in 5-HT

  6. Hydrodynamic drive of tubular centrifuges

    SciTech Connect

    Tsybul'nik, A.P.

    1986-07-01

    A drive has been developed for a tubular centrifuge having a 10 kW ASTs-10-504 high-frequency electric motor with a synchronous rotation speed of 15,000 rpm. Despite a few demerits, the drive met the basic production requirements; simplicity and reliability of design, admissable rotation speed, and explosion resistance. However, this drive for tubular centrifuges had to be abandoned because experimental prototypes of high-frequency motors were used for the industrial tests and lot production of such motors is not probable in the near future. Industrial tests of a new hydrodynamic drive were performed, and the schematic diagram is shown. The hydrodrive was tested during centrifuge operation with polyester lac. It was found that the hydodynamic drive is distinguished by operational reliability and easy serviceability, holds promise for increased centrifuge speed, ensures smooth start of the centrifuge and satisfactory stability of the rotor rotation speed in the steady regime, reliably protects the motor from overloading and is fully explosion-proof.

  7. The hydrodynamics of swimming microorganisms

    NASA Astrophysics Data System (ADS)

    Lauga, Eric; Powers, Thomas R.

    2009-09-01

    Cell motility in viscous fluids is ubiquitous and affects many biological processes, including reproduction, infection and the marine life ecosystem. Here we review the biophysical and mechanical principles of locomotion at the small scales relevant to cell swimming, tens of micrometers and below. At this scale, inertia is unimportant and the Reynolds number is small. Our emphasis is on the simple physical picture and fundamental flow physics phenomena in this regime. We first give a brief overview of the mechanisms for swimming motility, and of the basic properties of flows at low Reynolds number, paying special attention to aspects most relevant for swimming such as resistance matrices for solid bodies, flow singularities and kinematic requirements for net translation. Then we review classical theoretical work on cell motility, in particular early calculations of swimming kinematics with prescribed stroke and the application of resistive force theory and slender-body theory to flagellar locomotion. After examining the physical means by which flagella are actuated, we outline areas of active research, including hydrodynamic interactions, biological locomotion in complex fluids, the design of small-scale artificial swimmers and the optimization of locomotion strategies.

  8. Fluctuating hydrodynamics for ionic liquids

    NASA Astrophysics Data System (ADS)

    Lazaridis, Konstantinos; Wickham, Logan; Voulgarakis, Nikolaos

    2017-04-01

    We present a mean-field fluctuating hydrodynamics (FHD) method for studying the structural and transport properties of ionic liquids in bulk and near electrified surfaces. The free energy of the system consists of two competing terms: (1) a Landau-Lifshitz functional that models the spontaneous separation of the ionic groups, and (2) the standard mean-field electrostatic interaction between the ions in the liquid. The numerical approach used to solve the resulting FHD-Poisson equations is very efficient and models thermal fluctuations with remarkable accuracy. Such density fluctuations are sufficiently strong to excite the experimentally observed spontaneous formation of liquid nano-domains. Statistical analysis of our simulations provides quantitative information about the properties of ionic liquids, such as the mixing quality, stability, and the size of the nano-domains. Our model, thus, can be adequately parameterized by directly comparing our prediction with experimental measurements and all-atom simulations. Conclusively, this work can serve as a practical mathematical tool for testing various theories and designing more efficient mixtures of ionic liquids.

  9. Hydrodynamically enforced entropic Brownian pump

    NASA Astrophysics Data System (ADS)

    Ai, Bao-quan; He, Ya-feng; Li, Feng-guo; Zhong, Wei-rong

    2013-04-01

    Transport of overdamped Brownian particles in a finite hydrodynamical channel is investigated in the presence of the ac driving force and the pressure-driven flow. The system is bounded by two particle reservoirs. With the help of the Fick-Jacobs method, we obtain the directed current of Brownian particles and the pumping capacity of the system. The directed transport is determined by the competitions among the asymmetry of the channel, the ac driving force, the pressure-driven flow, and the concentration difference. Their interplays can exhibit the peculiar properties. Remarkably, the particles can be pumped through the channel from the lower concentration reservoir to the higher concentration one, or from the lower pressure side to the higher pressure one. In addition, due to the existence of the pressure drop, ac driving force still plays the significant role on directed transport even in a completely symmetric channel. Our results could be implemented in constrained structures with narrow channels or pores where the particles are suspended in a solvent.

  10. Detonation waves in relativistic hydrodynamics

    SciTech Connect

    Cissoko, M. )

    1992-02-15

    This paper is concerned with an algebraic study of the equations of detonation waves in relativistic hydrodynamics taking into account the pressure and the energy of thermal radiation. A new approach to shock and detonation wavefronts is outlined. The fluid under consideration is assumed to be perfect (nonviscous and nonconducting) and to obey the following equation of state: {ital p}=({gamma}{minus}1){rho} where {ital p}, {rho}, and {gamma} are the pressure, the total energy density, and the adiabatic index, respectively. The solutions of the equations of detonation waves are reduced to the problem of finding physically acceptable roots of a quadratic polynomial {Pi}({ital X}) where {ital X} is the ratio {tau}/{tau}{sub 0} of dynamical volumes behind and ahead of the detonation wave. The existence and the locations of zeros of this polynomial allow it to be shown that if the equation of state of the burnt fluid is known then the variables characterizing the unburnt fluid obey well-defined physical relations.

  11. Hydrodynamic Instabilities Produced by Evaporation

    NASA Astrophysics Data System (ADS)

    Romo-Cruz, Julio Cesar Ruben; Hernandez-Zapata, Sergio; Ruiz-Chavarria, Gerardo

    2012-11-01

    When a liquid layer (alcohol in the present work) is in an environment where its relative humidity is less than 100 percent evaporation appears. When RH is above a certain threshold the liquid is at rest. If RH decreases below this threshold the flow becomes unstable, and hydrodynamic cells develop. The aim of this work is to understand the formation of those cells and its main features. Firstly, we investigate how the cell size depends on the layer width. We also study how temperature depends on the vertical coordinate when the cells are present. An inverse temperature gradient is found, that is, the bottom of liquid layer is colder than the free surface. This shows that the intuitive idea that the cells are due to a direct temperature gradient, following a Marangoni-like process, does not work. We propose the hypothesis that the evaporation produce a pressure gradient that is responsible of the cell development. On the other hand, using a Schlieren technique we study the topography of the free surface when cells are present. Finally the alcohol vapor layer adjacent to the liquid surface is explored using scattering experiments, giving some insight on the plausibility of the hypothesis described previously. Authors acknowledge support by DGAPA-UNAM under project IN116312 ``Vorticidad y ondas no lineales en fluidos.''

  12. Smoothed particle hydrodynamics and magnetohydrodynamics

    NASA Astrophysics Data System (ADS)

    Price, Daniel J.

    2012-02-01

    This paper presents an overview and introduction to smoothed particle hydrodynamics and magnetohydrodynamics in theory and in practice. Firstly, we give a basic grounding in the fundamentals of SPH, showing how the equations of motion and energy can be self-consistently derived from the density estimate. We then show how to interpret these equations using the basic SPH interpolation formulae and highlight the subtle difference in approach between SPH and other particle methods. In doing so, we also critique several 'urban myths' regarding SPH, in particular the idea that one can simply increase the 'neighbour number' more slowly than the total number of particles in order to obtain convergence. We also discuss the origin of numerical instabilities such as the pairing and tensile instabilities. Finally, we give practical advice on how to resolve three of the main issues with SPMHD: removing the tensile instability, formulating dissipative terms for MHD shocks and enforcing the divergence constraint on the particles, and we give the current status of developments in this area. Accompanying the paper is the first public release of the NDSPMHD SPH code, a 1, 2 and 3 dimensional code designed as a testbed for SPH/SPMHD algorithms that can be used to test many of the ideas and used to run all of the numerical examples contained in the paper.

  13. Hydrodynamic aspects of fish olfaction

    PubMed Central

    Cox, Jonathan P.L

    2008-01-01

    Flow into and around the olfactory chamber of a fish determines how odorant from the fish's immediate environment is transported to the sensory surface (olfactory epithelium) lining the chamber. Diffusion times in water are long, even over comparatively short distances (millimetres). Therefore, transport from the external environment to the olfactory epithelium must be controlled by processes that rely on convection (i.e. the bulk flow of fluid). These include the beating of cilia lining the olfactory chamber and the relatively inexpensive pumping action of accessory sacs. Flow through the chamber may also be induced by an external flow. Flow over the olfactory epithelium appears to be laminar. Odorant transfer to the olfactory epithelium may be facilitated in several ways: if the olfactory organs are mounted on stalks that penetrate the boundary layer; by the steep velocity gradients generated by beating cilia; by devices that deflect flow into the olfactory chamber; by parallel arrays of olfactory lamellae; by mechanical agitation of the chamber (or olfactory stalks); and by vortices. Overall, however, our knowledge of the hydrodynamics of fish olfaction is far from complete. Several areas of future research are outlined. PMID:18184629

  14. GAMMA-RAY BURSTS ARE OBSERVED OFF-AXIS

    SciTech Connect

    Ryan, Geoffrey; Van Eerten, Hendrik; MacFadyen, Andrew; Zhang, Bin-Bin

    2015-01-20

    We constrain the jet opening angle and, for the first time, the off-axis observer angle for gamma-ray bursts in the Swift-XRT catalog by using the ScaleFit package to fit afterglow light curves directly to hydrodynamic simulations. The ScaleFit model uses scaling relations in the hydrodynamic and radiation equations to compute synthetic light curves directly from a set of high-resolution two-dimensional relativistic blast wave simulations. The data sample consists of all Swift-XRT afterglows from 2005 to 2012 with sufficient coverage and a known redshift, 226 bursts in total. We find that the jet half-opening angle varies widely but is commonly less than 0.1 rad. The distribution of the electron spectral index is also broad, with a median at 2.30. We find the observer angle to have a median value of 0.57 of the jet opening angle over our sample, which has profound consequences for the predicted rate of observed jet breaks and affects the beaming-corrected total energies of gamma-ray bursts.

  15. Simulated radiographic bone and joint modeling from 3D ankle MRI: feasibility and comparison with radiographs and 2D MRI.

    PubMed

    Nordeck, Shaun M; Koerper, Conrad E; Adler, Aaron; Malhotra, Vidur; Xi, Yin; Liu, George T; Chhabra, Avneesh

    2017-05-01

    The purpose of this work is to simulate radiographs from isotropic 3D MRI data, compare relationship of angle and joint space measurements on simulated radiographs with corresponding 2D MRIs and real radiographs (XR), and compare measurement times among the three modalities. Twenty-four consecutive ankles were included, eight males and 16 females, with a mean age of 46 years. Segmented joint models simulating radiographs were created from 3D MRI data sets. Three readers independently performed blinded angle and joint space measurements on the models, corresponding 2D MRIs, and XRs at two time points. Linear mixed models and the intraclass correlation coefficient (ICC) was ascertained, with p values less than 0.05 considered significant. Simulated radiograph models were successfully created in all cases. Good agreement (ICC > 0.65) was noted among all readers across all modalities and among most measurements. Absolute measurement values differed between modalities. Measurement time was significantly greater (p < 0.05) on 2D versus simulated radiographs for most measurements and on XR versus simulated radiographs (p < 0.05) for nearly half the measurements. Simulated radiographs can be successfully generated from 3D MRI data; however, measurements differ. Good inter-reader and moderate-to-good intra-reader reliability was observed and measurements obtained on simulated radiograph models took significantly less time compared to measurements with 2D and generally less time than XR.

  16. Low Reynolds number hydrodynamics and mesoscale simulations

    NASA Astrophysics Data System (ADS)

    Winkler, Roland G.

    2016-11-01

    Hydrodynamics and hydrodynamic interactions are fundamental for the motility of microswimmers. This includes the propulsion mechanism itself, the synchronized motion of flagella in flagellar bundles and beating cilia of cilia arrays, and even extends to collective behaviors. The general importance of hydrodynamics has stimulated the development of mesoscale simulation approaches to efficiently study dynamical properties of objects embedded in a fluid. In this minireview, the properties of flows at low Reynolds numbers are discussed, thereby the unsteady acceleration term is typically taken into account (Landau-Lifshitz Navier-Stokes equations). Specifically, the synchronization of microrotors by time-dependent hydrodynamic interactions is discussed and the propulsion of a rotating helix. Moreover, the multiparticle collisions dynamics method (MPC), a mesoscale simulation approach for fluids, is outlined. Simulation results for the flow field of a model E. Coli bacterium and its swimming behavior next to a surface are presented.

  17. Anisotropic hydrodynamic function of dense confined colloids

    NASA Astrophysics Data System (ADS)

    Nygârd, Kim; Buitenhuis, Johan; Kagias, Matias; Jefimovs, Konstantins; Zontone, Federico; Chushkin, Yuriy

    2017-06-01

    Dense colloidal dispersions exhibit complex wave-vector-dependent diffusion, which is controlled by both direct particle interactions and indirect nonadditive hydrodynamic interactions mediated by the solvent. In bulk the hydrodynamic interactions are probed routinely, but in confined geometries their studies have been hitherto hindered by additional complications due to confining walls. Here we solve this issue by combining high-energy x-ray photon correlation spectroscopy and small-angle x-ray-scattering experiments on colloid-filled microfluidic channels to yield the confined fluid's hydrodynamic function in the short-time limit. Most importantly, we find the confined fluid to exhibit a strongly anisotropic hydrodynamic function, similar to its anisotropic structure factor. This observation is important in order to guide future theoretical research.

  18. Hydrodynamic properties of carbon nanotubes.

    PubMed

    Walther, J H; Werder, T; Jaffe, R L; Koumoutsakos, P

    2004-06-01

    We study water flowing past an array of single walled carbon nanotubes using nonequilibrium molecular dynamics simulations. For carbon nanotubes mounted with a tube spacing of 16.4 x 16.4 nm and diameters of 1.25 and 2.50 nm, respectively, we find drag coefficients in reasonable agreement with the macroscopic, Stokes-Oseen solution. The slip length is -0.11 nm for the 1.25 nm carbon nanotube, and 0.49 for the 2.50 nm tube for a flow speed of 50 m/s, respectively, and 0.28 nm for the 2.50 nm tube at 200 m/s. A slanted flow configuration with a stream- and spanwise velocity component of 100 ms(-1) recovers the two-dimensional results, but exhibits a significant 88 nm slip along the axis of the tube. These results indicate that slip depends on the particular flow configuration.

  19. Hydrodynamic Instabilities at an Oblique Interface in the light to heavy configuration

    NASA Astrophysics Data System (ADS)

    Kuranz, Carolyn; Malamud, G.; Klein, S. R.; Trantham, M.; Drake, R. P.; Shvarts, D.; Wan, W. C.; Rasmus, A. M.; Flippo, K.; Kline, J.; di Stefano, C. A.; Shimony, A.

    2016-10-01

    Hydrodynamic instabilities are important phenomena that occur in many high-energy-density systems, including astrophysical systems and inertial confinement fusion experiments, where pressure, density, and velocity gradients are present. Using the Omega EP laser we have created a sustained shock platform to drive a steady shock wave using a 30 ns laser pulse. Coupled with a Spherical Crystal Imager we have created high-resolution x-ray radiographs to diagnose the evolution of complex hydrodynamic structures. This experiment involves a hydrodynamically unstable interface at an oblique angle so that the Richtmyer-Meshkov and Kelvin-Helmholtz processes are present. A precision-machined perturbation will grow due to shear and vorticity deposited at the interface. Preliminary data from recent experiments exploring the different growth between single and dual mode initial perturbations and simulations results will be shown. This work is supported by the U.S. DOE, through NNSA Grants_DE-NA0002956 (SSAA) and DE-NA0002719 (NLUF), by the LLE under DE-NA0001944, and by the LLNL under subcontract B614207 to DE-AC52-07NA27344 and by LANL under subcontract BA154750/SC343761.

  20. Angle interferometer cross axis errors

    NASA Astrophysics Data System (ADS)

    Bryan, J. B.; Carter, D. L.; Thompson, S. L.

    1994-01-01

    Angle interferometers are commonly used to measure surface plate flatness. An error can exist when the centerline of the double comer cube mirror assembly is not square to the surface plate and the guide bar for the mirror sled is curved. Typical errors can be one to two microns per meter. A similar error can exist in the calibration of rotary tables when the centerline of the double comer cube mirror assembly is not square to the axes of rotation of the angle calibrator and the calibrator axis is not parallel to the rotary table axis. Commercial double comer cube assemblies typically have non-parallelism errors of ten milli-radians between their centerlines and their sides and similar values for non-squareness between their centerlines and end surfaces. The authors have developed a simple method for measuring these errors and correcting them.

  1. Angle interferometer cross axis errors

    SciTech Connect

    Bryan, J.B.; Carter, D.L.; Thompson, S.L.

    1994-01-01

    Angle interferometers are commonly used to measure surface plate flatness. An error can exist when the centerline of the double comer cube mirror assembly is not square to the surface plate and the guide bar for the mirror sled is curved. Typical errors can be one to two microns per meter. A similar error can exist in the calibration of rotary tables when the centerline of the double comer cube mirror assembly is not square to the axes of rotation of the angle calibrator and the calibrator axis is not parallel to the rotary table axis. Commercial double comer cube assemblies typically have non-parallelism errors of ten milli-radians between their centerlines and their sides and similar values for non-squareness between their centerlines and end surfaces. The authors have developed a simple method for measuring these errors and correcting them by remachining the reference surfaces.

  2. Emotional Intelligence Throughout the Lifecycle of Australian Radiographers.

    PubMed

    Lewis, Sarah Jayne; Eccles, Grace Rose; Mackay, Stuart James; Robinson, John

    2017-09-01

    To measure global and domain trait emotional intelligence (EI) throughout the professional lifecycle of Australian radiographers and report the trends. A combination retrospective and prospective cross-sectional multiple-cohort study using the Trait Emotional Intelligence Questionnaire Short Form (TEIQue-SF) was designed to collect global and domain trait EI scores of several populations, including radiography students (n = 95), inexperienced radiographers (0-5 years' experience; n = 94), experienced radiographers (≥ 6 years' experience; n = 451), chief radiographers (n = 107), clinical educators (n = 24), application specialists (n = 24), and radiographers working in education (n = 15). Mean EI scores were calculated and statistical tests were performed to determine whether significant differences existed among the groups. Statistically significant differences were found among populations for global EI and the domains of self-control and well-being, with students demonstrating consistently lower scores than qualified radiographers (P ≥ .001). Chief radiographers demonstrated higher scores for well-being than inexperienced radiographers, radiographers working in education, and students (P < .001). Global EI scores increased steadily throughout the professional lifecycle of Australian radiographers, plateauing at 10 years of clinical experience. Chief radiographers demonstrated the highest scores for well-being, which is consistent with prior research acknowledging the importance of EI in organizational leadership. Students demonstrated lower EI scores likely because they are at the beginning of their careers and might not yet perceive themselves as confident or successful. Higher EI scores are expected in normal career advancement, plateauing at about 10 years of clinical experience. A statistically significant difference exists between global and domain trait EI scores throughout the professional lifecycle of Australian radiologic technologists. Global trait

  3. The radiographic union scale in tibial (RUST) fractures

    PubMed Central

    Clement, N. D.; Tawonsawatruk, T.; Simpson, C. J.; Simpson, A. H. R. W.

    2016-01-01

    Objectives The radiographic union score for tibial (RUST) fractures was developed by Whelan et al to assess the healing of tibial fractures following intramedullary nailing. In the current study, the repeatability and reliability of the RUST score was evaluated in an independent centre (a) using the original description, (b) after further interpretation of the description of the score, and (c) with the immediate post-operative radiograph available for comparison. Methods A total of 15 radiographs of tibial shaft fractures treated by intramedullary nailing (IM) were scored by three observers using the RUST system. Following discussion on how the criteria of the RUST system should be implemented, 45 sets (i.e. AP and lateral) of radiographs of IM nailed tibial fractures were scored by five observers. Finally, these 45 sets of radiographs were rescored with the baseline post-operative radiograph available for comparison. Results The initial intraclass correlation (ICC) on the first 15 sets of radiographs was 0.67 (95% CI 0.63 to 0.71). However, the original description was being interpreted in different ways. After agreeing on the interpretation, the ICC on the second cohort improved to 0.75. The ICC improved even further to 0.79, when the baseline post-operative radiographs were available for comparison. Conclusion This study demonstrates that the RUST scoring system is a reliable and repeatable outcome measure for assessing tibial fracture healing. Further improvement in the reliability of the scoring system can be obtained if the radiographs are compared with the baseline post-operative radiographs. Cite this article: Mr J.M. Leow. The radiographic union scale in tibial (RUST) fractures: Reliability of the outcome measure at an independent centre. Bone Joint Res 2016;5:116–121. DOI: 10.1302/2046-3758.54.2000628. PMID:27073210

  4. Model-based segmentation of hand radiographs

    NASA Astrophysics Data System (ADS)

    Weiler, Frank; Vogelsang, Frank

    1998-06-01

    An important procedure in pediatrics is to determine the skeletal maturity of a patient from radiographs of the hand. There is great interest in the automation of this tedious and time-consuming task. We present a new method for the segmentation of the bones of the hand, which allows the assessment of the skeletal maturity with an appropriate database of reference bones, similar to the atlas based methods. The proposed algorithm uses an extended active contour model for the segmentation of the hand bones, which incorporates a-priori knowledge of shape and topology of the bones in an additional energy term. This `scene knowledge' is integrated in a complex hierarchical image model, that is used for the image analysis task.

  5. Radiographic apparatus for photographing entire jaws

    SciTech Connect

    Nakano, K.

    1985-01-22

    This disclosure relates to a dental radiographic apparatus for photographing the entire jaw designed to control the rotation of a rotary arm such that the film surface of a film holder mounted at one end of the rotary arm may rotate and move substantially at equal speed substantially equidistantly along the dental arch and that the X-ray beams irradiated upon the film surface from an X-ray generator mounted at the other end of the arm may fall on the dental arch at any point thereof at right angles with the arch. The apparatus makes it possible to obtain a very clear tomographic picture of a curved plane of the entire jaws, the picture being free of a double image of the teeth, partial change in enlargement ratio of the image obtained, and partial difference in the shade of the image obtained.

  6. Temporal stability of digital radiographic detectors.

    PubMed

    Ireland, Timothy A; Irvine, Mike

    2016-03-01

    With the current preference for digital radiographic detectors in modern radiology facilities, there has been increasing demand for baseline technical data for equipment comparison and benchmarking. Key system parameters were monitored in 12 individual digital detectors over a 6 months period following installation, to establish baseline performance fluctuations for current generation indirect digital detectors. Performance criteria monitored included exposure index consistency, detector uniformity, system transfer function, artifact presentation, automatic exposure control reproducibility and dose area product consistency. Two indirect digital detector models were included, with the final set of measurements for each detector taken after routine detector calibrations were completed by technical staff. Suggested performance limits are presented based on observed temporal fluctuations, as well as national and international standards, where applicable.

  7. Radiographer perceptions of managerial transformational leadership levels.

    PubMed

    Legg, Jeffrey S; Akroyd, Duane; Jackowski, Melissa B

    2010-01-01

    Transformational leadership focuses on the ability of a leader to impact employees by inspiring employees to broaden interests in work as well as to be innovative and creative. It is positively associated with employee satisfaction and commitment to the organization. Characteristics of transformational leaders include confidence, ability to mange and deal with complexity, and belief in their employees and organizations. Considering the importance of leadership skills in radiology departments, this paper addresses directly the empirical evidence concerning radiographer's perception of their radiology managers and supervisors transformational leadership levels in the United States. Leadership can be taught, and we as a profession must begin to implement leadership training programs for our current and future leaders.

  8. Iterative Reconstruction of Coded Source Neutron Radiographs

    NASA Astrophysics Data System (ADS)

    Santos-Villalobos, Hector J.; Bingham, Philip R.; Gregor, Jens

    2013-06-01

    A coded source facilitates high-resolution neutron imaging through magnification but requires that the radiographic data be deconvolved. A comparison of convolution-based and model-based de-blurring algorithms has been performed. Two convolution-based approaches are assessed, direct deconvolution and an iterative algorithm based on a maximum likelihood estimation (MLE)-like framework. The model-based approach specifies a geometric model of the neutron beam with a least squares formulation of the inverse imaging problem. Simulated data for both uniform and Gaussian shaped source distributions was used to study the impact of non-uniformities present in neutron beam distributions on the reconstructed images. Results indicate that the model based reconstruction method will match resolution and improve on contrast over convolution methods in the presence of non-uniform sources. Additionally, the model based iterative algorithm provides direct calculation of quantitative transmission values while the convolution based methods must be normalized based on known values.

  9. Male Pectoral Implants: Radiographic Appearance of Complications

    PubMed Central

    Kuzmiak, Cherie M; Damitz, Lynn; Burke, Rachael; Hwang, Michael

    2016-01-01

    There has been a significant surge in aesthetic chest surgery for men in the last several years. Male chest enhancement is performed with surgical placement of a solid silicone pectoral implant. In the past, male chest correction and implantation were limited to the treatment of men who had congenital absence or atrophy of the pectoralis muscle and pectus excavatum deformity. But today, the popularization of increased chest and pectoral size fostered by body builders has more men desiring chest correction with implantation for non-medical reasons. We present a case of a 44-year-old, male with a displaced left pectoral implant with near extrusion and with an associated peri-implant soft tissue mass and fluid collection. While the imaging of these patients is uncommon, our case study presents the radiographic findings of male chest enhancement with associated complications. PMID:27200162

  10. Iterative Reconstruction of Coded Source Neutron Radiographs

    SciTech Connect

    Santos-Villalobos, Hector J; Bingham, Philip R; Gregor, Jens

    2013-01-01

    Use of a coded source facilitates high-resolution neutron imaging through magnifications but requires that the radiographic data be deconvolved. A comparison of direct deconvolution with two different iterative algorithms has been performed. One iterative algorithm is based on a maximum likelihood estimation (MLE)-like framework and the second is based on a geometric model of the neutron beam within a least squares formulation of the inverse imaging problem. Simulated data for both uniform and Gaussian shaped source distributions was used for testing to understand the impact of non-uniformities present in neutron beam distributions on the reconstructed images. Results indicate that the model based reconstruction method will match resolution and improve on contrast over convolution methods in the presence of non-uniform sources. Additionally, the model based iterative algorithm provides direct calculation of quantitative transmission values while the convolution based methods must be normalized base on known values.

  11. Radiographic examination takes on an automated image

    SciTech Connect

    Aman, J.

    1988-02-01

    Automation can be effectively applied to nondestructive testing (NDT). Until recently, film radiography used in NDT was largely a manual process, involving the shooting of a series of x-rays, manually positioned and manually processed. In other words, much radiographic work is being done the way it was over 50 years ago. Significant advances in automation have changed the face of manufacturing, and industry has shared in the benefits brought by such progress. The handling of parts, which was once responsible for a large measure of labor costs, is now assigned to robotic equipment. In nondestructive testing processes, some progress has been achieved in automation - for example, in real-time imaging systems. However, only recently have truly automated NDT begun to emerge. There are two major reasons to introduce automation into NDT - reliability and productivity. Any process or technique that can improve the reliability of parts testing could easily justify the capital investments required.

  12. The aging reproductive neuroendocrine axis.

    PubMed

    Brann, Darrell W; Mahesh, Virendra B

    2005-04-01

    It is well known that the reproductive system is one of the first biological systems to show age-related decline. While depletion of ovarian follicles clearly relates to the end of reproductive function in females, evidence is accumulating that a hypothalamic defect is critical in the transition from cyclicity to acyclicity. This minireview attempts to present a concise review on aging of the female reproductive neuroendocrine axis and provide thought-provoking analysis and insights into potential future directions for this field. Evidence will be reviewed, which shows that a defect in pulsatile and surge gonadotropin hormone-releasing hormone (GnRH) secretion exists in normal cycling middle-aged female rats, which is thought to explain the significantly attenuated pulsatile and surge luteinizing hormone (LH) secretion at middle-age. Evidence is also presented, which supports the age-related defect in GnRH secretion as being due to a reduced activation of GnRH neurons. Along these lines, stimulation of GnRH secretion by the major excitatory transmitter glutamate is shown to be significantly attenuated in middle-aged proestrous rats. Corresponding age-related defects in other major excitatory regulatory factors, such as catecholamines, neuropeptide Y, and astrocytes, have also been demonstrated. Age-related changes in hypothalamic concentrations of neurotransmitter receptors, steroid receptors, and circulating steroid hormone levels are also reviewed, and discussion is presented on the complex interrelationships of the hypothalamus-pituitary-ovarian (HPO) axis during aging, with attention to how a defect in one level of the axis can induce defects in other levels, and thereby potentiate the dysfunction of the entire HPO axis.

  13. Application of practical hydrodynamics to airship design

    NASA Technical Reports Server (NTRS)

    Upson, Ralph H; Klikoff, W A

    1933-01-01

    The purpose of the first two parts of this report is to present in concise format all the formulas required for computation of the hydrodynamic forces, so that they can be easily computed for either straight or curvilinear flight. Improved approximations are also introduced having a high degree of accuracy throughout the entire range of practical proportions. The remaining two parts of the report are devoted respectively to stability and skin friction, as functions of the same hydrodynamic forces.

  14. Hydrodynamics of bacterial colonies: Phase diagrams

    NASA Astrophysics Data System (ADS)

    Lega, J.; Passot, T.

    2004-09-01

    We present numerical simulations of a recent hydrodynamic model describing the growth of bacterial colonies on agar plates. We show that this model is able to qualitatively reproduce experimentally observed phase diagrams, which relate a colony shape to the initial quantity of nutrients on the plate and the initial wetness of the agar. We also discuss the principal features resulting from the interplay between hydrodynamic motions and colony growth, as described by our model.

  15. Quasiparticle anisotropic hydrodynamics for central collisions

    NASA Astrophysics Data System (ADS)

    Alqahtani, Mubarak; Nopoush, Mohammad; Strickland, Michael

    2017-03-01

    We use quasiparticle anisotropic hydrodynamics to study an azimuthally symmetric boost-invariant quark-gluon plasma including the effects of both shear and bulk viscosities. In quasiparticle anisotropic hydrodynamics, a single finite-temperature quasiparticle mass is introduced and fit to the lattice data in order to implement a realistic equation of state (EoS). We compare results obtained by using the quasiparticle method with the standard method of imposing the EoS in anisotropic hydrodynamics and viscous hydrodynamics. Using these three methods, we extract the primordial particle spectra, total number of charged particles, and average transverse momentum for various values of the shear viscosity to entropy density ratio η /s . We find that the three methods agree well for small shear viscosity to entropy density ratio η /s , but differ at large η /s , with the standard anisotropic EoS method showing suppressed production at low transverse-momentum compared with the other two methods considered. Finally, we demonstrate explicitly that, when using standard viscous hydrodynamics, the bulk-viscous correction can drive the primordial particle spectra negative at large pT. Such behavior is not seen in either anisotropic hydrodynamics approach, irrespective of the value of η /s .

  16. Hydrodynamics of soft active matter

    NASA Astrophysics Data System (ADS)

    Marchetti, M. C.; Joanny, J. F.; Ramaswamy, S.; Liverpool, T. B.; Prost, J.; Rao, Madan; Simha, R. Aditi

    2013-07-01

    This review summarizes theoretical progress in the field of active matter, placing it in the context of recent experiments. This approach offers a unified framework for the mechanical and statistical properties of living matter: biofilaments and molecular motors in vitro or in vivo, collections of motile microorganisms, animal flocks, and chemical or mechanical imitations. A major goal of this review is to integrate several approaches proposed in the literature, from semimicroscopic to phenomenological. In particular, first considered are “dry” systems, defined as those where momentum is not conserved due to friction with a substrate or an embedding porous medium. The differences and similarities between two types of orientationally ordered states, the nematic and the polar, are clarified. Next, the active hydrodynamics of suspensions or “wet” systems is discussed and the relation with and difference from the dry case, as well as various large-scale instabilities of these nonequilibrium states of matter, are highlighted. Further highlighted are various large-scale instabilities of these nonequilibrium states of matter. Various semimicroscopic derivations of the continuum theory are discussed and connected, highlighting the unifying and generic nature of the continuum model. Throughout the review, the experimental relevance of these theories for describing bacterial swarms and suspensions, the cytoskeleton of living cells, and vibrated granular material is discussed. Promising extensions toward greater realism in specific contexts from cell biology to animal behavior are suggested, and remarks are given on some exotic active-matter analogs. Last, the outlook for a quantitative understanding of active matter, through the interplay of detailed theory with controlled experiments on simplified systems, with living or artificial constituents, is summarized.

  17. Associations between dietary antioxidants intake and radiographic knee osteoarthritis.

    PubMed

    Li, Hui; Zeng, Chao; Wei, Jie; Yang, Tuo; Gao, Shu-Guang; Li, Yu-Sheng; Lei, Guang-Hua

    2016-06-01

    The aim of the study is to examine the cross-sectional associations between dietary antioxidants (carotenoid, vitamin C, E, and selenium) intake and radiographic knee osteoarthritis (OA). A total of 4685 participants were included in this study. Dietary intake was assessed using a validated semi-quantitative food frequency questionnaire. Radiographic knee OA was defined as Kellgren-Lawrence (K-L) grade 2 in at least one leg. A multivariable logistic analysis model was established to test the relationship between dietary antioxidants (carotenoid, vitamin C, E, and selenium) intake and radiographic knee OA with adjustment of a number of potential confounding factors. A significant positive association between dietary vitamin C intake (P value for trend was 0.04 in multivariable adjusted analysis) and radiographic knee OA was observed. The relative odds of radiographic knee OA were increased by 0.39 times in the third quintile (OR 1.39, 95 % CI 1.11-1.73), 0.42 times in the fourth quintile (OR 1.42, 95 % CI 1.13-1.79), and 0.33 times in the fifth quintile (OR 1.33, 95 % CI 1.03-1.71). However, radiographic knee OA was not significantly associated with dietary carotenoid, vitamin E, and selenium. Among dietary antioxidants, dietary vitamin C intake was positively correlated with the prevalence of radiographic knee OA, while no significant association was found between dietary intake of carotenoid, vitamin E, and selenium and the prevalence of radiographic knee OA.

  18. 10 CFR 34.41 - Conducting industrial radiographic operations.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.41... qualified radiographer or an individual who has at a minimum met the requirements of § 34.43(c). The... the requirements for having two qualified individuals present at locations other than a...

  19. 10 CFR 34.41 - Conducting industrial radiographic operations.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.41... qualified radiographer or an individual who has at a minimum met the requirements of § 34.43(c). The... the requirements for having two qualified individuals present at locations other than a...

  20. 10 CFR 34.46 - Supervision of radiographers' assistants.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... 10 Energy 1 2014-01-01 2014-01-01 false Supervision of radiographers' assistants. 34.46 Section 34.46 Energy NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.46 Supervision...

  1. 10 CFR 34.46 - Supervision of radiographers' assistants.

    Code of Federal Regulations, 2011 CFR

    2011-01-01

    ... 10 Energy 1 2011-01-01 2011-01-01 false Supervision of radiographers' assistants. 34.46 Section 34.46 Energy NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.46 Supervision...

  2. 10 CFR 34.41 - Conducting industrial radiographic operations.

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.41... qualified radiographer or an individual who has at a minimum met the requirements of § 34.43(c). The... the requirements for having two qualified individuals present at locations other than a...

  3. 10 CFR 34.46 - Supervision of radiographers' assistants.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... 10 Energy 1 2012-01-01 2012-01-01 false Supervision of radiographers' assistants. 34.46 Section 34.46 Energy NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.46 Supervision...

  4. 10 CFR 34.46 - Supervision of radiographers' assistants.

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... 10 Energy 1 2013-01-01 2013-01-01 false Supervision of radiographers' assistants. 34.46 Section 34.46 Energy NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.46 Supervision...

  5. 10 CFR 34.41 - Conducting industrial radiographic operations.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.41... qualified radiographer or an individual who has at a minimum met the requirements of § 34.43(c). The... the requirements for having two qualified individuals present at locations other than a...

  6. 10 CFR 34.41 - Conducting industrial radiographic operations.

    Code of Federal Regulations, 2012 CFR

    2012-01-01

    ... SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.41... qualified radiographer or an individual who has at a minimum met the requirements of § 34.43(c). The... the requirements for having two qualified individuals present at locations other than a...

  7. 10 CFR 34.46 - Supervision of radiographers' assistants.

    Code of Federal Regulations, 2010 CFR

    2010-01-01

    ... 10 Energy 1 2010-01-01 2010-01-01 false Supervision of radiographers' assistants. 34.46 Section 34.46 Energy NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Radiation Safety Requirements § 34.46 Supervision...

  8. Are Panoramic Radiographs Reliable to Diagnose Mild Alveolar Bone Resorption?

    PubMed Central

    Semenoff, Larissa; Semenoff, Tereza Aparecida Delle; Pedro, Fabio Luiz Miranda; Volpato, Evaristo Ricci; Machado, Maria Aparecida de Andrade Moreira; Borges, Álvaro Henrique; Semenoff-Segundo, Alex

    2011-01-01

    It is extremely important to assess variations between the most used radiographs in dental practice, since minimum distortion on obtained images may change diagnosis, treatment plan, and prognosis for the patient. For this, the distance between the enamel-cementum junction and the alveolar bone crest was measured on conventional and digitized periapical, bitewing, and panoramic radiographs and compared among them. From a total of 1484 records, 39 sets of radiographs that fulfilled the inclusion criteria of the study sample were selected. The measurements were grouped according to the intensity of bone loss. Statistically significant difference was found in the averages of the measurements assessed in radiographs with absence of bone loss between conventional panoramic and periapical radiographs, between digitized panoramic and periapical radiographs and between digitized bitewing and panoramic radiographs. By analyzing the results of this work and considering the research protocol used, one can conclude that small losses in height of alveolar bone crest observed in panoramic radiographs should be cautiously evaluated, as they may be overestimated. PMID:21991470

  9. Are panoramic radiographs reliable to diagnose mild alveolar bone resorption?

    PubMed

    Semenoff, Larissa; Semenoff, Tereza Aparecida Delle; Pedro, Fabio Luiz Miranda; Volpato, Evaristo Ricci; Machado, Maria Aparecida de Andrade Moreira; Borges, Alvaro Henrique; Semenoff-Segundo, Alex

    2011-01-01

    It is extremely important to assess variations between the most used radiographs in dental practice, since minimum distortion on obtained images may change diagnosis, treatment plan, and prognosis for the patient. For this, the distance between the enamel-cementum junction and the alveolar bone crest was measured on conventional and digitized periapical, bitewing, and panoramic radiographs and compared among them. From a total of 1484 records, 39 sets of radiographs that fulfilled the inclusion criteria of the study sample were selected. The measurements were grouped according to the intensity of bone loss. Statistically significant difference was found in the averages of the measurements assessed in radiographs with absence of bone loss between conventional panoramic and periapical radiographs, between digitized panoramic and periapical radiographs and between digitized bitewing and panoramic radiographs. By analyzing the results of this work and considering the research protocol used, one can conclude that small losses in height of alveolar bone crest observed in panoramic radiographs should be cautiously evaluated, as they may be overestimated.

  10. Video enhancement of X-ray and neutron radiographs

    NASA Technical Reports Server (NTRS)

    Vary, A.

    1973-01-01

    System was devised for displaying radiographs on television screen and enhancing fine detail in picture. System uses analog-computer circuits to process television signal from low-noise television camera. Enhanced images are displayed in black and white and can be controlled to vary degree of enhancement and magnification of details in either radiographic transparencies or opaque photographs.

  11. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic ECG/respirator synchronizer. 892.1970 Section 892.1970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic...

  12. 21 CFR 892.1920 - Radiographic head holder.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic head holder. 892.1920 Section 892.1920 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1920 Radiographic head holder....

  13. 21 CFR 892.1950 - Radiographic anthropomorphic phantom.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic anthropomorphic phantom. 892.1950 Section 892.1950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1950 Radiographic...

  14. 21 CFR 892.1950 - Radiographic anthropomorphic phantom.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic anthropomorphic phantom. 892.1950 Section 892.1950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1950 Radiographic...

  15. 21 CFR 892.1920 - Radiographic head holder.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic head holder. 892.1920 Section 892.1920 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1920 Radiographic head holder....

  16. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic ECG/respirator synchronizer. 892.1970 Section 892.1970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic...

  17. 21 CFR 892.1920 - Radiographic head holder.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic head holder. 892.1920 Section 892.1920 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1920 Radiographic head holder....

  18. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic ECG/respirator synchronizer. 892.1970 Section 892.1970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic...

  19. 21 CFR 892.1960 - Radiographic intensifying screen.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 8 2014-04-01 2014-04-01 false Radiographic intensifying screen. 892.1960 Section 892.1960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1960 Radiographic intensifying...

  20. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic ECG/respirator synchronizer. 892.1970 Section 892.1970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic...

  1. 21 CFR 892.1960 - Radiographic intensifying screen.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 8 2012-04-01 2012-04-01 false Radiographic intensifying screen. 892.1960 Section 892.1960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1960 Radiographic intensifying...

  2. 21 CFR 892.1960 - Radiographic intensifying screen.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic intensifying screen. 892.1960 Section 892.1960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1960 Radiographic intensifying...

  3. 21 CFR 892.1950 - Radiographic anthropomorphic phantom.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic anthropomorphic phantom. 892.1950 Section 892.1950 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1950 Radiographic...

  4. 21 CFR 892.1920 - Radiographic head holder.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 8 2013-04-01 2013-04-01 false Radiographic head holder. 892.1920 Section 892.1920 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1920 Radiographic head holder....

  5. 21 CFR 892.1920 - Radiographic head holder.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic head holder. 892.1920 Section 892.1920 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1920 Radiographic head holder....

  6. 42 CFR 37.8 - Radiographic examination at miner's expense.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF UNDERGROUND COAL MINERS Chest Roentgenographic Examinations § 37.8 Radiographic examination at miner's expense. Any miner who wishes to obtain an examination... 42 Public Health 1 2013-10-01 2013-10-01 false Radiographic examination at miner's expense. 37.8...

  7. 42 CFR 37.80 - Availability of records for radiographs.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... AND EXAMINATIONS SPECIFICATIONS FOR MEDICAL EXAMINATIONS OF COAL MINERS Chest Radiographic... information and radiographs on miners will be released by NIOSH only with the written consent from the miner, or if the miner is deceased, written consent from the miner's widow or widower, next of kin, or legal...

  8. A Study of Radiographic Imaging Systems Used for Dental Hygiene.

    ERIC Educational Resources Information Center

    Karst, Nancy S.

    Thirty-three two-year dental hygiene programs throughout the United States were surveyed to identify the radiographic imaging system most often used and the accompanying rationale for that decision. A literature review identified the three radiographic imaging systems most frequently used and indicated that all dental hygiene programs had the…

  9. 10 CFR Appendix A to Part 34 - Radiographer Certification

    Code of Federal Regulations, 2014 CFR

    2014-01-01

    ... NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Pt. 34, App. A Appendix A to Part 34—Radiographer Certification I... of industrial radiography; 2. Make its membership available to the general public nationwide that is...

  10. 10 CFR Appendix A to Part 34 - Radiographer Certification

    Code of Federal Regulations, 2013 CFR

    2013-01-01

    ... NUCLEAR REGULATORY COMMISSION LICENSES FOR INDUSTRIAL RADIOGRAPHY AND RADIATION SAFETY REQUIREMENTS FOR INDUSTRIAL RADIOGRAPHIC OPERATIONS Pt. 34, App. A Appendix A to Part 34—Radiographer Certification I... of industrial radiography; 2. Make its membership available to the general public nationwide that is...

  11. 21 CFR 892.1960 - Radiographic intensifying screen.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 8 2011-04-01 2011-04-01 false Radiographic intensifying screen. 892.1960 Section 892.1960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1960 Radiographic intensifying screen...

  12. 21 CFR 892.1960 - Radiographic intensifying screen.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic intensifying screen. 892.1960 Section 892.1960 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1960 Radiographic intensifying screen...

  13. 21 CFR 892.1970 - Radiographic ECG/respirator synchronizer.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Radiographic ECG/respirator synchronizer. 892.1970 Section 892.1970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES RADIOLOGY DEVICES Diagnostic Devices § 892.1970 Radiographic ECG/respirator...

  14. A Study of Radiographic Imaging Systems Used for Dental Hygiene.

    ERIC Educational Resources Information Center

    Karst, Nancy S.

    Thirty-three two-year dental hygiene programs throughout the United States were surveyed to identify the radiographic imaging system most often used and the accompanying rationale for that decision. A literature review identified the three radiographic imaging systems most frequently used and indicated that all dental hygiene programs had the…

  15. Reperfusion edema after thromboendarterectomy: radiographic patterns of disease.

    PubMed

    Miller, W T; Osiason, A W; Langlotz, C P; Palevsky, H I

    1998-07-01

    In patients with chronic pulmonary embolism, pulmonary thromboendarterectomy may result in a unique form of noncardiogenic pulmonary edema termed reperfusion edema. This report reviews the authors' experience after pulmonary thromboendarterectomy with particular emphasis on the radiographic manifestations of reperfusion edema. The clinical and radiographic record of 25 patients who underwent pulmonary thromboendarterectomy at the University of Pennsylvania from 1985 through 1995 were reviewed. The zonal distribution of radiographic opacity, time to maximal opacity, and the time to clearance of reperfusion edema were determined. The relationship of these radiographic manifestations to clinical severity of disease and clinical outcome was examined. Reperfusion edema, characterized by patchy bilateral perihilar alveolar opacities, occurred in all but one patient. There is a lower lung zone predominance of opacities, but in individual cases, striking unilateral or haphazard arrangements of opacities may be seen. In this small sample of patients, no association between preoperative pulmonary arterial pressures and radiographic appearance or clinical outcome was found. However, severity of radiographic opacities, as measured by the extent of involved lung, correlated with disease severity, as measured by time to extubation and time to discharge. Pneumonia, defined as a radiographic opacity that evolves discordantly with the reperfusion edema opacities, occurred in 20% of cases. Reperfusion edema is a common consequence of pulmonary thromboendarterectomy. The severity of radiographic manifestations and clinical severity of disease are related. This characteristically appears as perihilar alveolar opacities.

  16. True oblique axis fracture associated with congenital anomalies of the upper cervical spine: Case report of an unusual fracture pattern

    PubMed Central

    Robles, Luis A.

    2017-01-01

    Background: Acute traumatic axis fractures are common cervical spine injuries often caused by road accidents or falls. They are usually classified into three different types, namely, odontoid fractures, Hangman's fractures, and miscellaneous fractures. Congenital malformations of the craniovertebral junction (CVJ), although typically asymptomatic, may result in neural compression or instability, especially following trauma. Here, the authors present an unusual oblique axis fracture occurring in conjunction with several malformations of the upper cervical spine. Case Description: Following a motor vehicle accident, a 25-year-old female's radiographic studies showed an oblique axis fracture involving both the anterior and posterior elements along with an anterior and posterior Klippel–Feil syndrome (KFS) anomaly. Following treatment in a halo vest, the patient maintained alignment, and ultimately the fracture was fused. Conclusions: True oblique fractures of the axis are rare, as in the case presented, and may occasionally occur in conjunction with KFS of the upper cervical spine. PMID:28217386

  17. Radiographic Parameters in Adult Degenerative Scoliosis and Different Parameters Between Sagittal Balanced and Imbalanced ADS Patients.

    PubMed

    Yang, Changwei; Yang, Mingyuan; Chen, Yuanyuan; Wei, Xianzhao; Ni, Haijian; Chen, Ziqiang; Li, Jingfeng; Bai, Yushu; Zhu, Xiaodong; Li, Ming

    2015-07-01

    A retrospective study. To summarize and describe the radiographic parameters of adult degenerative scoliosis (ADS) and explore the radiological parameters which are significantly different in sagittal balanced and imbalanced ADS patients. ADS is the most common type of adult spinal deformity. However, no comprehensive description of radiographic parameters in ADS patients has been made, and few studies have been performed to explore which radiological parameters are significantly different between sagittal balanced and imbalanced ADS patients. Medical records of ADS patients in our outpatient clinic from January 2012 to January 2014 were reviewed. Demographic data including age and sex, and radiographic data including the coronal Cobb angle, location of apical vertebra/disc, convexity of the curve, degree of apical vertebra rotation, curve segments, thoracic kyphosis (TK), lumbar lordosis (LL), thoracolumbar kyphosis (TL), sacral slope (SS), pelvic tilt (PT), pelvic incidence (PI), sagittal vertical axis (SVA), and PI minus LL (PI-LL) were reviewed to make comprehensive description of radiographic parameters of ADS. Furthermore, patients were divided into 2 groups according to whether the patients' sagittal plane was balanced: Group A (imbalanced, SVA > 5 cm) and Group B (balanced, SVA  ≤ 5 cm). Demographic and radiological parameters were compared between these 2 groups. A total of 99 patients were included in this study (Group A = 33 and Group B = 66; female = 83 and male = 16; sex ratio = 5:1). The median of age were 67 years (range: 41-92 years). The median of coronal Cobb angle and length of curve was 23 (range: 10-75°) and 5 segments (range: 3-7), respectively. The most common location of apical vertebra was at L2 to L3 (81%) and the median of degree of apical vertebra rotation was 2° (range: 1-3). Our study also showed significant correlations between coronal Cobb angle and curve segments (r = 0.23, P < 0.005) and degree of apical vertebra rotation (r

  18. Thoracic radiographic anatomy in vervet monkeys (Chlorocebus sabaeus).

    PubMed

    Young, Aisha N; du Plessis, Wencke M; Rodriguez, Daniel; Beierschmitt, Amy

    2013-12-01

    The vervet monkey (Chlorocebus sabaeus) is used commonly in cardiorespiratory biomedical research. This study was performed to establish reference values for thoracic structures and to describe the normal radiographic appearance of the vervet monkey thorax. Right lateral and dorsoventral thoracic radiographs of ten mature vervet monkeys were evaluated. Anatomic structures were characterized using descriptive statistics. Normal measurements of skeletal, pulmonary, mediastinal, and cardiovascular structures are reported herein. Several ratios were calculated to assess the cardiac silhouette, caudal vena cava, and pulmonary arteries and veins. Consistent measurements could be made on the majority of the thoracic structures evaluated. The aorta on lateral radiographs and the pulmonary veins on dorsoventral radiographs were obscured by a mild bronchointerstitial pattern and body conformation. Caudal vena cava-tapering was occasionally noted and attributed to general anesthesia. Species-specific thoracic radiographic reference values should prove useful in vervet monkey disease diagnosis and management. © 2013 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

  19. Human Identification via Lateral Patella Radiographs: A Validation Study.

    PubMed

    Niespodziewanski, Emily; Stephan, Carl N; Guyomarc'h, Pierre; Fenton, Todd W

    2016-01-01

    This research examines the utility of patella outline shape for matching 3D scans of patellae to knee radiographs using elliptical Fourier analysis and subjective methods of human visual comparison of patellae across radiographs for identification purposes. Repeat radiographs were captured of cadaver's knees for visual comparison before patellae were extracted and skeletonized for quantitative comparisons. Quantitative methods provided significant narrowing down of the candidate pool to just a few potential matches (<5% of original sample), while the human analysts showed high capacity for correctly matching radiographs, irrespective of educational level (positive predictive value = 99.8%). The successful computerized matching based on a single quantified patella trait (outline shape) helps explain the potency achieved by subjective visual examination. This work adds to a growing body of studies demonstrating the value of single isolated infracranial bones for human identification via radiographic comparison.

  20. Determinants Of Acceptability Of Radiographic Images For Archival Digital Storage

    NASA Astrophysics Data System (ADS)

    Markivee, C. R.; Nalesnik, W. J.; Chiang, M. C.; Tio, J. R.; Hall, E. L.

    1983-05-01

    The parameter, quality of radiographic film exposure, was evaluated by computer and 15 human observers for the purpose of determining the feasibility of automatic computer eval-uation of radiographs prior to archival storage. Histograms of digitized knee radiographs were parameterized according to the Pearson technique and the computer was used to grade exposure quality relative to a set of training radiographs evaluated by the readers. There was a significant variation in the assessment of film exposure quality among the different observers. The computer scored 73% for the AP films and 53% for the laterals relative to the general consensus. The discrepancies were explained in terms of differences in anatomy and radiographic technique. The significance of this work is that it demonstrates that a computer can grade films according to a predetermined standard set by the radiologist.

  1. Radiographic appearance of confirmed pulmonary lymphoma in cats and dogs.

    PubMed

    Geyer, Nicole E; Reichle, Jean K; Valdés-Martínez, Alejandro; Williams, Jamie; Goggin, Justin M; Leach, Lesley; Hanson, Jennifer; Hill, Steve; Axam, Tasha

    2010-01-01

    Herein we describe the thoracic radiographic appearance of confirmed pulmonary lymphoma. Patients with thoracic radiographs and cytologically or histologically confirmed pulmonary lymphoma were sought by contacting American College of Veterinary Radiology members. Seven cats and 16 dogs met the inclusion criteria, ranging in age from 4 to 15 years. Method of diagnosis was via ultrasound-guided cytology (four), surgical biopsy (two), ultrasound-guided biopsy (one), and necropsy (16). Radiographic findings varied but ranged from normal (one) to alveolar (six) and/or unstructured interstitial infiltrates (11), nodules and/or masses (eight), and bronchial infiltrates (four). Additional thoracic radiographic findings included pleural effusion and lymphadenopathy. The results of this evaluation indicate a wide variability in thoracic radiographic abnormalities in cats and dogs with pulmonary lymphoma.

  2. Computer-assisted assembly and correction simulation for complex axis deviations using the Ilizarov fixator.

    PubMed

    Kochs, A

    1995-01-01

    In axis correction with the Ilizarov ring fixator, the correction results are often insufficient or there are unexpected translation effects, which can be causally attributed to wrong preoperative planning or inaccurate assembly. To avoid such results, computerised simulation was developed. Via digitalisation of the bone outlines traced from X-radiographs with an additional scale, preoperative correction planning can be performed, simulated with normal software. This can be used while constructing the apparatus and positioning the joints. In addition, the translation effect of the bone fragments can be simulated by arbitrarily choosing the pivot of the correction. In transferring the X-radiograph true to scale, one can compare the ring planes before and after correction. It is possible to estimate the necessary distraction as well as compression and thus the postoperative distraction mode. Using computerised planning, the apparatus construction can be optimised and complications caused by misplanning avoided. Not only the inexperienced user can benefit from this aid.

  3. Io's Volcanoes: Possible Influence on Spin Axis

    NASA Astrophysics Data System (ADS)

    Stoddard, P. R.; Jurdy, D. M.

    2002-03-01

    Massive outpourings of lava in short intervals could cause an instability in Io's rotation and a reorientation of its spin axis. The volcanos and mountains exhibit a complementary distribution, with the maximum principal inertia axis for volcanos close to the position of the rotation axis.

  4. The Radical Axis: A Motion Study

    ERIC Educational Resources Information Center

    McGivney, Ray; McKim, Jim

    2006-01-01

    Interesting problems sometimes have surprising sources. In this paper we take an innocent looking problem from a calculus book and rediscover the radical axis of classical geometry. For intersecting circles the radical axis is the line through the two points of intersection. For nonintersecting, nonconcentric circles, the radical axis still…

  5. Which lateral radiographic positioning technique provides the most reliable and functional representation of a patient's sagittal balance?

    PubMed

    Marks, Michelle; Stanford, Chriss; Newton, Peter

    2009-04-20

    Prospective nonscoliotic cohort evaluation of the effects of various positions for obtaining standing lateral thoracolumbar radiographs. The purpose of this study was to compare the effects of various upper extremity positions on thoracolumbar sagittal spinal alignment. The standing position used to capture a lateral plane radiograph can have marked effects on measurements of sagittal spinal alignment and may compound the variability between measurements from successive radiographs. Twenty-two healthy female adolescents performed 3 repeated trials of 4 standing positions in a motion analysis laboratory. The positions included: (1) relaxed standing with arms at sides (CONTROL), (2) standing with fists overlying ipsilateral clavicles (CLAVICLE), (3) active shoulder flexion to 30 degrees with elbows extended (30 ACTIVE), and (4) passive shoulder flexion to 30 degrees with hand supports (30 PASSIVE). Sagittal alignment of the spine was described by kyphosis, lordosis, and the sagittal vertical axis (SVA), all of which were measured from the positions of reflective markers attached to the surface of the back and pelvis. Differences between alignment measures obtained for each of the 3 radiographic positions relative to the functional position (CONTROL) were calculated. Mean differences were then compared between positions using repeated measures ANOVAs (alpha = 0.05). Relative to the CONTROL position, all other positions resulted in negative shifts in SVA (range = -1.1 cm- -4.6 cm), decreased kyphosis (range = -1 degrees- -3 degrees), and increased lordosis (4 degrees for all positions). The shift in the SVA with the 30 PASSIVE position was significantly less than the other 2 positions (P < 0.05) and demonstrated the least variability. Standing with the hands supported while flexing the shoulders 30 degrees during positioning for lateral spinopelvic radiographic acquisition resulted in an SVA and measures of sagittal plane curvature that were comparable with a

  6. Quadruple Axis Neutron Computed Tomography

    NASA Astrophysics Data System (ADS)

    Schillinger, Burkhard; Bausenwein, Dominik

    Neutron computed tomography takes more time for a full tomography than X-rays or Synchrotron radiation, because the source intensity is limited. Most neutron imaging detectors have a square field of view, so if tomography of elongated, narrow samples, e.g. fuel rods, sword blades is recorded, much of the detector area is wasted. Using multiple rotation axes, several samples can be placed inside the field of view, and multiple tomographies can be recorded at the same time by later splitting the recorded images into separate tomography data sets. We describe a new multiple-axis setup using four independent miniaturized rotation tables.

  7. Triple axis and spins spectrometers

    SciTech Connect

    Trevino, S.F.

    1993-01-01

    In the paper are described the triple axis and spin polarized inelastic neutron scattering (SPINS) spectrometers which are installed at the NIST Cold Neutron Research Facility (CNRF). The general principle of operation of these two instruments is described in sufficient detail to allow the reader to make an informed decision as to their usefulness for his needs. However, it is the intention of the staff at the CNRF to provide the expert resources for their efficient use in any given situation. Thus, the work is not intended as a user manual but rather as a guide into the range of applicability of the two instruments.

  8. Radiographic outcomes among South African coal miners.

    PubMed

    Naidoo, Rajen N; Robins, Thomas G; Solomon, A; White, Neil; Franzblau, Alfred

    2004-10-01

    This study, the first to document the prevalence of pneumoconiosis among a living South African coal mining cohort, describes dose-response relationships between coal workers' pneumoconiosis and respirable dust exposure, and relationships between pneumoconiosis and both lung function deterioration and respiratory symptoms. A total of 684 current miners and 188 ex-miners from three bituminous-coal mines in Mpumalanga, South Africa, was studied. Chest radiographs were read according to the International Labour Organization (ILO) classification by two experienced readers, one an accredited National Institute for Occupational Safety and Health (NIOSH) "B" reader. Interviews were conducted to assess symptoms, work histories (also obtained from company records), smoking, and other risk factors. Spirometry was performed by trained technicians. Cumulative respirable dust exposure (CDE) estimates were constructed from historical company-collected sampling and researcher-collected personal dust measurements. kappa-Statistics compared the radiographic outcomes predicted by the two readers. An average profusion score was used in the analysis for the outcomes of interest. Because of possible confounding by employment status, most analyses were stratified on current and ex-miner status. The overall prevalence of pneumoconiosis was low (2%-4%). The degree of agreement between the two readers for profusion was moderate to high (kappa=0.58). A significant association (P<0.001) and trend (P<0.001) was seen for pneumoconiosis with increasing categories of CDE among current miners only. A significant (P<0.0001) additional 58 mg-years/m3 CDE was seen among those with pneumoconiosis compared to those without. CDE contributed to a statistically significant 0.19% and 0.11% greater decline in the percent predicted 1-second forced expiration volume (FEV1) and forced vital capacity (FVC), respectively, among current miners with pneumoconiosis than among those without. Logistic regression

  9. Radiographic anatomy of the proximal femur: correlation with the occurrence of fractures

    PubMed Central

    Pires, Robinson Esteves Santos; Prata, Eric Fontes; Gibram, Athos Vilela; Santos, Leandro Emilio Nascimento; Lourenço, Paulo Roberto Barbosa de Toledo; Belloti, João Carlos

    2012-01-01

    Objective To evaluate the correlation between radiographic parameters of the proximal femur anatomy and fractures. Methods Three hundred and five digital x-rays of the pelvis were analyzed in the anteroposterior view. Of these x-rays, twenty-seven showed femoral neck or transtrochanteric fractures. The anatomical parameters analyzed were: femoral neck width (FNW), femoral neck length (FNL), femoral axis length (FAL), cervicodiaphyseal angle (CDA), acetabular tear-drop distance (ATD) and great trochanter-pubic symphysis distance (GTPSD). The analysis was performed by comparing the results of the x-rays with and without proximal femoral fracture, to establish a correlation between them. Results No differences were found between the anatomical parameters of the groups with and without proximal femoral fracture. Conclusion There was no association between anatomical changes in the proximal femur and greater susceptibility to fractures. Level of evidence IV, Cross-sectional Study. PMID:24453585

  10. New formulation of leading order anisotropic hydrodynamics

    NASA Astrophysics Data System (ADS)

    Tinti, Leonardo

    2015-05-01

    Anisotropic hydrodynamics is a reorganization of the relativistic hydrodynamics expansion, with the leading order already containing substantial momentum-space anisotropies. The latter are a cause of concern in the traditional viscous hydrodynamics, since large momentum anisotropies generated in ultrarelativistic heavy-ion collisions are not consistent with the hypothesis of small deviations from an isotropic background, i.e., from the local equilibrium distribution. We discuss the leading order of the expansion, presenting a new formulation for the (1+1)- dimensional case, namely, for the longitudinally boost invariant and cylindrically symmetric flow. This new approach is consistent with the well established framework of Israel and Stewart in the close to equilibrium limit (where we expect viscous hydrodynamics to work well). If we consider the (0+1)-dimensional case, that is, transversally homogeneous and longitudinally boost invariant flow, the new form of anisotropic hydrodynamics leads to better agreement with known solutions of the Boltzmann equation than the previous formulations, especially when we consider massive particles.

  11. Hydrodynamic approaches in relativistic heavy ion reactions

    NASA Astrophysics Data System (ADS)

    Derradi de Souza, R.; Koide, T.; Kodama, T.

    2016-01-01

    We review several facets of the hydrodynamic description of the relativistic heavy ion collisions, starting from the historical motivation to the present understandings of the observed collective aspects of experimental data, especially those of the most recent RHIC and LHC results. In this report, we particularly focus on the conceptual questions and the physical foundations of the validity of the hydrodynamic approach itself. We also discuss recent efforts to clarify some of the points in this direction, such as the various forms of derivations of relativistic hydrodynamics together with the limitations intrinsic to the traditional approaches, variational approaches, known analytic solutions for special cases, and several new theoretical developments. Throughout this review, we stress the role of course-graining procedure in the hydrodynamic description and discuss its relation to the physical observables through the analysis of a hydrodynamic mapping of a microscopic transport model. Several questions to be answered to clarify the physics of collective phenomena in the relativistic heavy ion collisions are pointed out.

  12. On the definition of discrete hydrodynamic variables.

    PubMed

    Español, Pep; Zúñiga, Ignacio

    2009-10-28

    The Green-Kubo formula for discrete hydrodynamic variables involves information about not only the fluid transport coefficients but also about discrete versions of the differential operators that govern the evolution of the discrete variables. This gives an intimate connection between discretization procedures in fluid dynamics and coarse-graining procedures used to obtain hydrodynamic behavior of molecular fluids. We observed that a natural definition of discrete hydrodynamic variables in terms of Voronoi cells leads to a Green-Kubo formula which is divergent, rendering the full coarse-graining strategy useless. In order to understand this subtle issue, in the present paper we consider the coarse graining of noninteracting Brownian particles. The discrete hydrodynamic variable for this problem is the number of particles within Voronoi cells. Thanks to the simplicity of the model we spot the origin of the singular behavior of the correlation functions. We offer an alternative definition, based on the concept of a Delaunay cell that behaves properly, suggesting the use of the Delaunay construction for the coarse graining of molecular fluids at the discrete hydrodynamic level.

  13. Anisotropic hydrodynamics for conformal Gubser flow

    NASA Astrophysics Data System (ADS)

    Strickland, Michael; Nopoush, Mohammad; Ryblewski, Radoslaw

    2016-12-01

    In this proceedings contribution, we review the exact solution of the anisotropic hydrodynamics equations for a system subject to Gubser flow. For this purpose, we use the leading-order anisotropic hydrodynamics equations which assume that the distribution function is ellipsoidally symmetric in local-rest-frame momentum. We then prove that the SO(3)q symmetry in de Sitter space constrains the anisotropy tensor to be of spheroidal form with only one independent anisotropy parameter remaining. As a consequence, the exact solution reduces to the problem of solving two coupled non-linear differential equations. We show that, in the limit that the relaxation time goes to zero, one obtains Gubser's ideal hydrodynamic solution and, in the limit that the relaxation time goes to infinity, one obtains the exact free streaming solution obtained originally by Denicol et al. For finite relaxation time, we solve the equations numerically and compare to the exact solution of the relaxation-time-approximation Boltzmann equation subject to Gubser flow. Using this as our standard, we find that anisotropic hydrodynamics describes the spatio-temporal evolution of the system better than all currently known dissipative hydrodynamics approaches.

  14. Scaling supernova hydrodynamics to the laboratory

    SciTech Connect

    Kane, J O; Remington, B A; Arnett, D; Fryxell, B A; Drake, R P

    1998-11-10

    Supernova (SN) 1987A focused attention on the critical role of hydrodynamic instabilities in the evolution of supernovae. To test the modeling of these instabilities, they are attempting to rigorously scale the physics of the laboratory in supernova. The scaling of hydrodynamics on microscopic laser scales to hydrodynamics on the SN-size scales is presented and requirements established. Initial results were reported in [1]. Next the appropriate conditions are generated on the NOVA laser. 10-15 Mbar shock at the interface of a two-layer planar target, which triggers perturbation growth, due to the Richtmyer-Meshkov instability and to the Rayleigh-Taylor instability as the interface decelerates is generated. This scales the hydrodynamics of the He-H interface of a Type II supernova at intermediate times, up to a few x10{sup 3} s. The experiment is modeled using the hydrodynamics codes HYADES and CALE, and the supernova code PROMETHEUS. Results of the experiments and simulations are presented. Analysis of the spike bubble velocities using potential flow theory and Ott thin shell theory is presented, as well as a study of 2D vs. 3D difference in growth at the He-H interface of Sn 1987A.

  15. Hydrodynamic Modeling and Its Application in AUC.

    PubMed

    Rocco, Mattia; Byron, Olwyn

    2015-01-01

    The hydrodynamic parameters measured in an AUC experiment, s(20,w) and D(t)(20,w)(0), can be used to gain information on the solution structure of (bio)macromolecules and their assemblies. This entails comparing the measured parameters with those that can be computed from usually "dry" structures by "hydrodynamic modeling." In this chapter, we will first briefly put hydrodynamic modeling in perspective and present the basic physics behind it as implemented in the most commonly used methods. The important "hydration" issue is also touched upon, and the distinction between rigid bodies versus those for which flexibility must be considered in the modeling process is then made. The available hydrodynamic modeling/computation programs, HYDROPRO, BEST, SoMo, AtoB, and Zeno, the latter four all implemented within the US-SOMO suite, are described and their performance evaluated. Finally, some literature examples are presented to illustrate the potential applications of hydrodynamics in the expanding field of multiresolution modeling. © 2015 Elsevier Inc. All rights reserved.

  16. Stress and the HPA Axis

    PubMed Central

    Stephens, Mary Ann C.; Wand, Gary

    2012-01-01

    Stress has long been suggested to be an important correlate of uncontrolled drinking and relapse. An important hormonal response system to stress—the hypothalamic–pituitary–adrenal (HPA) axis—may be involved in this process, particularly stress hormones known as glucocorticoids and primarily cortisol. The actions of this hormone system normally are tightly regulated to ensure that the body can respond quickly to stressful events and return to a normal state just as rapidly. The main determinants of HPA axis activity are genetic background, early-life environment, and current life stress. Alterations in HPA axis regulation are associated with problematic alcohol use and dependence; however, the nature of this dysregulation appears to vary with respect to stage of alcohol dependence. Much of this research has focused specifically on the role of cortisol in the risk for, development of, and relapse to chronic alcohol use. These studies found that cortisol can interact with the brain’s reward system, which may contribute to alcohol’s reinforcing effects. Cortisol also can influence a person’s cognitive processes, promoting habit-based learning, which may contribute to habit formation and risk of relapse. Finally, cortisol levels during abstinence may be useful clinical indicators of relapse vulnerability in alcohol-dependent people. PMID:23584113

  17. Flexible helical-axis stellarator

    DOEpatents

    Harris, Jeffrey H.; Hender, Timothy C.; Carreras, Benjamin A.; Cantrell, Jack L.; Morris, Robert N.

    1988-01-01

    An 1=1 helical winding which spirals about a conventional planar, circular central conductor of a helical-axis stellarator adds a significant degree of flexibility by making it possible to control the rotational transform profile and shear of the magnetic fields confining the plasma in a helical-axis stellarator. The toroidal central conductor links a plurality of toroidal field coils which are separately disposed to follow a helical path around the central conductor in phase with the helical path of the 1=1 winding. This coil configuration produces bean-shaped magnetic flux surfaces which rotate around the central circular conductor in the same manner as the toroidal field generating coils. The additional 1=1 winding provides flexible control of the magnetic field generated by the central conductor to prevent the formation of low-order resonances in the rotational transform profile which can produce break-up of the equilibrium magnetic surfaces. Further, this additional winding can deepen the magnetic well which together with the flexible control provides increased stability.

  18. Gut microbiota-bone axis.

    PubMed

    Villa, Christopher R; Ward, Wendy E; Comelli, Elena M

    2017-05-24

    The gut microbiota (GM) is an important regulator of body homeostasis, including intestinal and extra-intestinal effects. This review focuses on the GM-bone axis, which we define as the effect of the gut-associated microbial community or the molecules they synthesize, on bone health. While research in this field is limited, findings from preclinical studies support that gut microbes positively impact bone mineral density and strength parameters. Moreover, administration of beneficial bacteria (probiotics) in preclinical models has demonstrated higher bone mineralization and greater bone strength. The preferential bacterial genus that has shown these beneficial effects in bone is Lactobacillus and thus lactobacilli are among the best candidates for future clinical intervention trials. However, their effectiveness is dependent on stage of development, as early life constitutes an important time for impacting bone health, perhaps via modulation of the GM. In addition, sex-specific difference also impacts the efficacy of the probiotics. Although auspicious, many questions regarding the GM-bone axis require consideration of potential mechanisms; sex-specific efficacy; effective dose of probiotics; and timing and duration of treatment.

  19. Radiographic abnormalities among construction workers exposed to quartz containing dust

    PubMed Central

    Tjoe, N; Burdorf, A; Parker, J; Attfield, M; van Duivenbooden, C; Heederik, D

    2003-01-01

    Background: Construction workers are exposed to quartz containing respirable dust, at levels that may cause fibrosis in the lungs. Studies so far have not established a dose-response relation for radiographic abnormalities for this occupational group. Aims: To measure the extent of radiographic abnormalities among construction workers primarily exposed to quartz containing respirable dust. Methods: A cross sectional study on radiographic abnormalities indicative of pneumoconiosis was conducted among 1339 construction workers mainly involved in grinding, (jack)-hammering, drilling, cutting, sawing, and polishing. Radiological abnormalities were determined by median results of the 1980 International Labour Organisation system of three certified "B" readers. Questionnaires were used for assessment of occupational history, presence of respiratory diseases, and symptoms and smoking habits. Results: An abnormality of ILO profusion category 1/0 and greater was observed on 10.2% of the chest radiographs, and profusion category of 1/1 or greater on 2.9% of the radiographs. The average duration of exposure of this group was 19 years and the average age was 42. The predominant type of small opacities (irregularly shaped) is presumably indicative of mixed dust pneumoconiosis. The prevalence of early signs of nodular silicosis (small rounded opacities of category 1/0 or greater) was low (0.8%). Conclusions: The study suggests an elevated risk of radiographic abnormalities among these workers with expected high exposure. An association between radiographic abnormalities and cumulative exposure to quartz containing dust from construction sites was observed, after correction for potentially confounding variables. PMID:12771392

  20. Quantitative localization of impacted mesiodens using panoramic and periapical radiographs.

    PubMed

    Choi, Hang-Moon; Han, Jin-Woo; Park, In-Woo; Baik, Jee-Seon; Seo, Hyun-Woo; Lee, Joo-Hyun; Park, Ho-Won

    2011-06-01

    The purpose of this study was to evaluate a new technique for localizing impacted mesiodens using its horizontal magnification ratio on panoramic radiographs. Location-magnification equation of a panoramic equipment was obtained from horizontal magnification ratio of a metal ball which was located variable positions from the center of image layer at interval of 2 mm. Panoramic radiographs were obtained from a skull phantom with a metal ball which was a substitute for impacted mesiodens and was embedded 10mm(Group 1), 15mm(Group 2), and 20mm(Group 3) posterior to the central incisor. Each group obtained 7 panoramic radiographs at variable positions and one periapical radiograph. Three methods were used to estimate the actual width of the incisors and the balls which were used to calculate the magnification ratio. The methods included using the actual incisor width and the calculated ball width (Method 1), using the actual incisor width and the ball widths measured on periapical radiograph (Method 2), and using the incisor and the ball widths measured on periapical radiograph (Method 3). The location of the metal ball was calculated by using the location-magnification equation. The smallest difference between the calculated and the actual distance was 0.1±0.7 mm in Group 1/Method 3. The largest difference was -4.2±1.6 mm in Group 3/Method 2. In all groups, method 3 was the most accurate. Quantitative localization of impacted mesiodens is possible by using panoramic radiograph.