WorldWideScience

Sample records for spinning disc sprayer

  1. Use of polystyrene spin-coated compact discs for microimmunoassaying

    International Nuclear Information System (INIS)

    Tamarit-Lopez, Jesus; Morais, Sergi; Puchades, Rosa; Maquieira, Angel

    2008-01-01

    The analytical potential of polystyrene (PS) spin-coated modified compact discs (CDs) surface as platforms for the development of microarray immunoassays is presented. The surface maintained the optical characteristics of compact discs, obtaining a transparent and smooth film polymer of 70 nm thickness, the track being read (λ 780 nm) without errors in a commercial CD reader/writer. The analytical capability of the methodology was demonstrated through an analysis of a neurotoxic compound (2560 spots per disc), reaching 0.08 μg L -1 as limit of detection. These figures demonstrate the enormous potential of using PS spin-coated compact discs in combination with CD players as an easy-to-operate and portable device to develop lab-on-a-disc analytical applications

  2. Electric field numerical simulation of disc type electrostatic spinning spinneret

    Science.gov (United States)

    Wei, L.; Deng, ZL; Qin, XH; Liang, ZY

    2018-01-01

    Electrospinning is a new type of free-end spinning built on electric field. Different from traditional single needle spinneret, in this study, a new disc type free surface spinneret is used to produce multiple jets, this will greatly improve production efficiency of nanofiber. The electric-field distribution of spinneret is the crux of the formation and trajectory of jets. In order to probe the electric field intensity of the disc type spinneret, computational software of Ansoft Maxwell 12 is adopted for a precise and intuitive analysis. The results showed that the whole round cambered surface of the spinning solution at edge of each layer of the spinneret with the maximum curvature has the highest electric field intensity, and through the simulation of the electric field distribution of different spinneret parameters such as layer, the height and radius of the spinneret. Influences of various parameters on the electrostatic spinning are obtained.

  3. Dipole-exchange spin waves in perpendicularly magnetized discs: Role of the Oersted field

    Science.gov (United States)

    Arias, R. E.; Mills, D. L.

    2007-06-01

    We develop the theory of the exchange dipole spin waves in thin circular discs for the case where the magnetization is nominally perpendicular to the plane. Our interest is in the circumstance where a transport current is injected into the disc, with current also perpendicular to the plane of the disc. Such a current creates an azimuthal magnetic field, referred to often as the Oersted field. We develop the theory of the influence of the Oersted field on the spin-wave spectrum of the disc. This field produces a vortex state. We suggest that this vortex state is stable down to zero applied field. If the external applied field H0 is in the +z direction, perpendicular to the plane of the disc, the vortex state has magnetization at the center of the disc also parallel to +z always. This is the case even when H0<4πMS , where the magnetization at the center of the disc is antiparallel to the local field H0-4πMS there. We present calculations of the current dependence of spin-wave frequencies of several modes as a function of applied magnetic field. We also address an issue overlooked in previous studies of spin waves in thin discs. This is that for quantitative purposes, it is not sufficient to describe internal dipole fields generated by the spin motions simply by adding an effective internal field -4πmzẑ to the equations of motion, with mz the component of dynamic magnetization normal to the surface. For samples of present interest, we derive terms we call gradient corrections, and these play a role quantitatively comparable to exchange itself in the analysis of the spin-wave frequencies. Quantitative studies of spin dynamics in such samples thus must include the gradient corrections.

  4. Effect of high-frequency excitation on natural frequencies of spinning discs

    DEFF Research Database (Denmark)

    Hansen, Morten Hartvig

    2000-01-01

    The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural frequenc......The effect of high-frequency, non-resonant parametric excitation on the low-frequency response of spinning discs is considered. The parametric excitation is obtained through a non-constant rotation speed, where the frequency of the pulsating overlay is much higher than the lowest natural...

  5. Recirculating sprayer for fiber-filled paints

    Science.gov (United States)

    Major, R. K.

    1980-01-01

    Recirculating paint sprayer applies spray of coarse filler in highly volatile solvent. Sprayer was developed for applying insulation material containing epxoy resin, glass fibers, and inert fillers suspended in chlorinated solvents. Sprayer resists abrasive action of fiberglass filler and chemical activity of solvent. Pump and position ensure more uniform pressure at spray gun without backpressure regulator, which tended to clog in old sprayer.

  6. Dynamic Analysis of The Intelligent Sprayer Boom

    DEFF Research Database (Denmark)

    Wiggers, Sine Leergaard; Maagaard, Jørgen; Terp, Christian Istjord

    As part of the 3 year project “The intelligent Sprayer Boom”, financed by The Danish National Advanced Technology Foundation, the dynamics of the sprayer boom is to be analysed. In order to minimize the amount of herbicides used to kill the weeds in agriculture a new sprayer boom is being developed...... called “The intelligent sprayer boom”. For the sprayer boom the primary challenge is to hit the weeds with precision from a movable platform. Since the sprayer boom is mounted on a tractor the system will react to bumps in the field. The intelligent sprayer boom has an integrated camera technology...... system to work properly. At the University of Southern Denmark (SDU) a patent for an active damping system of the sprayer boom has been obtained. The subject of this paper is analysis of the dynamics of the Sprayer boom. The analysis is based on a Multibody Dynamics model of the sprayer boom and is made...

  7. Studying Of Preparation Silver Nano-Particles Using Spinning Disc Reactor

    International Nuclear Information System (INIS)

    Hoang Van Duc; Nguyen Thanh Chung; Tran Ngoc Ha; Ho Minh Quang; Nguyen Thi Thuc Phuong

    2014-01-01

    Preparation of silver nano-particles using spinning disc reactor has been investigated. The effects of technological factors and experimental conditions such as: concentrations of AgNO 3 , glucose, PVP, spinning speed, ect. on quality of nano-silver particles have been studied. With experimental conditions: rotation speed of 2000 rpm, weight rate of m PVP :m AgNO 3 = 1, AgNO 3 concentration of 0.01 M, glucose concentration of 0.02 M, silver particles of about 12 nm were obtained and the nano-silver solution were stable for more than 40 days. (author)

  8. What Makes the Family of Barred Disc Galaxies So Rich: Damping Stellar Bars in Spinning Haloes

    Science.gov (United States)

    Collier, Angela; Shlosman, Isaac; Heller, Clayton

    2018-02-01

    We model and analyze the secular evolution of stellar bars in spinning dark matter (DM) haloes with the cosmological spin λ ˜ 0 - 0.09. Using high-resolution stellar and DM numerical simulations, we focus on angular momentum exchange between stellar discs and DM haloes of various axisymmetric shapes — spherical, oblate and prolate. We find that stellar bars experience a diverse evolution which is guided by the ability of parent haloes to absorb angular momentum, J, lost by the disc through the action of gravitational torques, resonant and non-resonant. We confirm that dynamical bar instability is accelerated via resonant J-transfer to the halo. Our main findings relate to the long-term, secular evolution of disc-halo systems: with an increasing λ, bars experience less growth and basically dissolve after they pass through vertical buckling instability. Specifically, with increasing λ, (1) The vertical buckling instability in stellar bars colludes with inability of the inner halo to absorb J — this emerges as the main factor weakening or destroying bars in spinning haloes; (2) Bars lose progressively less J, and their pattern speeds level off; (3) Bars are smaller, and for λ ≳ 0.06 cease their growth completely following buckling; (4) Bars in λ > 0.03 halos have ratio of corotation-to-bar radii, RCR/Rb > 2, and represent so-called slow bars without offset dust lanes. We provide a quantitative analysis of J-transfer in disc-halo systems, and explain the reasons for absence of growth in fast spinning haloes and its observational corollaries. We conclude that stellar bar evolution is substantially more complex than anticipated, and bars are not as resilient as has been considered so far.

  9. CFD Modelling of the Effects of Operating Parameters on the Spreading of Liquids on a Spinning Disc

    Directory of Open Access Journals (Sweden)

    Y. Pan

    2014-03-01

    Full Text Available A novel dry slag granulation process based on a spinning disc is being developed by CSIRO. This process utilises centrifugal force to break up molten slag into droplets, which are then quenched into solidified granules by a flow of cold air. In this process the sensible heat of slag is recovered as hot air. In the present work, a previously developed steady-state, two-dimensional and multiphase CFD model was applied to perform parametric numerical experiments to investigate the effects of a number of parameters on the liquid film thickness at the disc edge, which included liquid mass feeding (pouring rate, disc spinning speed, disc radius, liquid viscosity, density and surface tension. The modelling results were compared with experimental data and were found to be in good agreement. To reduce the number of simulations needed, Box and Behnken's fractional factorial design of numerical experiment was adopted. Furthermore, in order for the modelling results to be applicable to atomisation of different liquids using spinning discs of different sizes, a dimensionless correlation was developed based on dimensional analysis of the numerical simulation data. The modelling results indicate that the liquid film thickness can be significantly influenced by the disc radius and spinning speed, the liquid mass feeding rate, viscosity and density, whereas the liquid surface tension has a negligible effect.

  10. Flit-gun sprayer characteristics

    Directory of Open Access Journals (Sweden)

    J. R. Brown

    1998-05-01

    Full Text Available Six flit-gun sprayers were tested for possible use in mosquito adulticide programs where inexpensive nonmotorized application technology may be required. An analysis of variance for differences in droplets or = 48 µ, droplets/cm², volume median diameters, and mosquito mortality is provided. As shown by these data, good results can be achieved with this equipment.

  11. Irradiation of an Accretion Disc by a Jet: General Properties and Implications for Spin Measurements of Black Holes

    Science.gov (United States)

    T.Dauser; Garcia, J.; Wilms, J.; Boeck, M.; Brenneman, L. W.; Falanga, M.; Fukumura, Keigo; Reynolds, C. S.

    2013-01-01

    X-ray irradiation of the accretion disc leads to strong reflection features, which are then broadened and distorted by relativistic effects. We present a detailed, general relativistic approach to model this irradiation for different geometries of the primary X-ray source. These geometries include the standard point source on the rotational axis as well as more jet-like sources, which are radially elongated and accelerating. Incorporating this code in the RELLINE model for relativistic line emission, the line shape for any configuration can be predicted. We study how different irradiation geometries affect the determination of the spin of the black hole. Broad emission lines are produced only for compact irradiating sources situated close to the black hole. This is the only case where the black hole spin can be unambiguously determined. In all other cases the line shape is narrower, which could either be explained by a low spin or an elongated source. We conclude that for those cases and independent of the quality of the data, no unique solution for the spin exists and therefore only a lower limit of the spin value can be given

  12. Structural Analysis of Field Sprayer Booms

    OpenAIRE

    KOÇ, Caner

    2017-01-01

    In this paper, structural analysis of a 21 meters wide field sprayer boom, designed for precision agricultureapplications, was conducted with finite element analysis. G-programming language, a data acquisition board andan inductive force transducer were used to measure the forces acting on the boom arms. An experimental setup,developed in a laboratory environment, was able to measure and record various forces in 5 miliseconds intervals.An ANSYS model was developed to analyze the forces record...

  13. Modeling and simulation of the agricultural sprayer boom leveling system

    KAUST Repository

    Sun, Jian

    2011-01-01

    According to the agricultural precision requirements, the distance from sprayer nozzles to the corps should be kept between 50 cm to 70 cm. The sprayer boom also needs to be kept parallel to the field during the application process. Thus we can guarantee the quality of the chemical droplets distribution on the crops. In this paper we design a sprayer boom leveling system for agricultural sprayer vehicles combined with a four-rod linkage self-leveling suspension and electro-hydraulic auto-leveling system. The dynamic analysis shows that the suspension can realize an excellent self-leveling in a comparative small inclination range. In addition we build compensation controller for the electro-hydraulic system based on the mathematical model. With simulations we can optimize the performance of this controller to make sure a fast leveling response to the inclined sprayer boom. © 2011 IEEE.

  14. Weed Control Sprayers: Calibration and Maintenance. Special Circular 81.

    Science.gov (United States)

    Myers, Arthur L.

    This manual covers aspects of calibration and maintenance of weed control sprayers including variables affecting application rate, the pre-calibration check, calculations, band spraying, nozzle tip selection, agitation, and cleaning. (BB)

  15. An innovative pneumatic electrostatic sprayer useful for tendone vineyards

    Directory of Open Access Journals (Sweden)

    Simone Pascuzzi

    2015-10-01

    Full Text Available The aim of this note is to analyse the features of the ESS 150 RB14 electrostatic sprayer, an innovative model compared to the standard air-assisted sprayers traditionally used by Apulian growers (Southern Italy in tendone vineyards. The experimental tests showed that the activation of the electrostatic system produced a significant increase in the mean deposit, but it was located only on the foliar layer of the canopy closer to the sprayer. However this result should also imply an increase in the deposits on the bunches when the electrostatic system is activated, even if further tests are necessary to verify this expectation. If this will be substantiated, the electrostatic sprayer ESS 150 RB14 would be suitable for the targeted applications usually performed in tendone table grape vineyards.

  16. Machine vision-based high-resolution weed mapping and patch-sprayer performance simulation

    NARCIS (Netherlands)

    Tang, L.; Tian, L.F.; Steward, B.L.

    1999-01-01

    An experimental machine vision-based patch-sprayer was developed. This sprayer was primarily designed to do real-time weed density estimation and variable herbicide application rate control. However, the sprayer also had the capability to do high-resolution weed mapping if proper mapping techniques

  17. Zinc and Selenium levels in Motor Mechanics, Paints Sprayers ...

    African Journals Online (AJOL)

    Objectives: This work was designed to determine zinc and Selenium levels in Motor Mechanics, Paints Sprayers, Smokers, Lubricant Workers and BatteryWorkers exposed to lead in Nnewi, South Eastern Nigeria. Subjects and methods: 100 exposed subjects were used for the study. The subjects were aged 25-30 years.

  18. The effect of the air blast sprayer speed on the chemical distribution in vineyard.

    Science.gov (United States)

    Celen, I H; Arin, S; Durgut, M R

    2008-06-01

    A study was conducted to determine the spray deposition patterns for air blast sprayers used to apply chemicals to the canopy of Semillon grapevine in vineyard. The application carried out in 12 bars and three sprayer speed (2.1-4.9-7.7 km h(-1)). The spray deposition was measured on the point in the different distances (1.5-3-6-9 m). Tartrazine were applied as tracer material. Maximum spray deposit was obtained 66.1 mg cm(-2) at sprayer speed of 2.1 km h(-1) and minimum deposit was obtained 37.1 mg cm(-2) at sprayer speed of 7.7 km h(-1). The results showed that the sprayer speeds had significant effect on spray deposit distribution and increasing of the sprayer speed increased drift.

  19. PID Controller of Sprayer Chassis by Sliding Mode

    Directory of Open Access Journals (Sweden)

    Hua Zhang

    2017-01-01

    Full Text Available In order to solve the straight line drive coordinated control problem of the four-wheel independent drive sprayer chassis, the dynamic model of sprayer chassis and electromagnetic proportional valve controlled hydraulic motor model are established. The additional yaw moment is designed to rectify the deviation with sliding mode variable structure control. PID control strategy is used to calculate the control voltage adjustment of the electromagnetic proportional valve. The simulation results show that the accumulative deviation of the chassis is 0.2 m out of 100 m when the coordinated control strategy is adopted on different adhesive coefficient pavement, which is much smaller than the value without control. The test results of test prototype show that the yaw acceleration of the chassis can be as low as −0.0132 m/s2 on different adhesive coefficient pavement with coordinated control, which is smaller than the value without control, and the straight line drive requirements are met. It is feasible to combine sliding mode variable structure with PID control and use the electromagnetic proportional control technology in the straight line drive coordinated control of sprayer chassis by adding the yaw moment to rectify the deviation of chassis based on the yaw acceleration detection.

  20. Deposition and Characterization of the Titanium-Based Coating by a Multi-Chamber Detonation Sprayer

    Directory of Open Access Journals (Sweden)

    Arseenko M.Yu.

    2015-01-01

    Full Text Available This work introduces some of the aspects of the deposition of titanium-based coating (80-120 μm thick on aluminium samples using a multi-chamber detonation sprayer (MCDS. The characteristic feature of MCDS is that the powder is accelerated by using combustion products that are formed in MCDS chambers and are converged before entering the nozzle, where they interact with the two-phase gas-powder cloud. The microstructures and properties of the coating were characterized with the use of scanning electronic microscopes (SEM, optical microscope (OM, X-ray Diffraction (XRD techniques, and Vickers hardness tester with a 50 g test load. Wear tests were carried out using a computer controlled pin-on-disc type tribometer. It was established that MCDS has provided the conditions for formation of a dense titanium-based coating with a porosity of less than 1.0%, microhardness 810±250 HV0.05 and a specific wear rate of 2.077∙10-4 mm3(m∙N-1.

  1. Simulation and controller design for an agricultural sprayer boom leveling system

    KAUST Repository

    Sun, Jian

    2011-01-01

    According to the agricultural precision requirements, the distance from sprayer nozzles to the corps should be kept between 50 cm to 70 cm. The sprayer boom also needs to be kept parallel to the field during the operation process. Thus we can guarantee the quality of the chemical droplets distribution on the crops. In this paper we introduced a sprayer boom leveling system for agricultural sprayer vehicles with electro-hydraulic auto-leveling system. The suitable hydraulic actuating cylinder and valve were selected according to the specific systemic specifications. Furthermore, a compensation controller for the electro-hydraulic system was designed based on the mathematical model. With simulations we can optimize the performance of this controller to make sure a fast leveling response to the inclined sprayer boom. © 2011 IEEE.

  2. Degenerative disc disease of the lumbar spine: a prospective comparison of fast T1-weighted fluid-attenuated inversion recovery and T1-weighted turbo spin echo MR imaging

    International Nuclear Information System (INIS)

    Erdem, L. Oktay; Erdem, C. Zuhal; Acikgoz, Bektas; Gundogdu, Sadi

    2005-01-01

    Objective: To compare fast T1-weighted fluid-attenuated inversion recovery (FLAIR) and T1-weighted turbo spin-echo (TSE) imaging of the degenerative disc disease of the lumbar spine. Materials and methods: Thirty-five consecutive patients (19 females, 16 males; mean age 41 years, range 31-67 years) with suspected degenerative disc disease of the lumbar spine were prospectively evaluated. Sagittal images of the lumbar spine were obtained using T1-weighted TSE and fast T1-weighted FLAIR sequences. Two radiologists compared these sequences both qualitatively and quantitatively. Results: On qualitative evaluation, CSF nulling, contrast at the disc-CSF interface, the disc-spinal cord (cauda equina) interface, and the spinal cord (cauda equina)-CSF interface of fast T1-weighted FLAIR images were significantly higher than those for T1-weighted TSE images (P < 0.001). On quantitative evaluation of the first 15 patients, signal-to-noise ratios of cerebrospinal fluid of fast T1-weighted FLAIR imaging were significantly lower than those for T1-weighted TSE images (P < 0.05). Contrast-to-noise ratios of spinal cord/CSF and normal bone marrow/disc for fast T1-weighted FLAIR images were significantly higher than those for T1-weighted TSE images (P < 0.05). Conclusion: Results in our study have shown that fast T1-weighted FLAIR imaging may be a valuable imaging modality in the armamentarium of lumbar spinal T1-weighted MR imaging, because the former technique has definite superior advantages such as CSF nulling, conspicuousness of the normal anatomic structures and changes in the lumbar spinal discogenic disease and image contrast and also almost equally acquisition times

  3. Quantification of emissions from knapsack sprayers: 'the weight method

    Science.gov (United States)

    Garcia-Santos, Glenda; Binder, Claudia R.

    2010-05-01

    Misuse of pesticides kill or seriously sicken thousands of people every year and poison the natural environment. Investigations of occupational and environmental risk have received considerable interest over the last decades. And yet, lack of staff and analytical equipments as well the costs of chemical analyses make difficult, if not impossible, the control of the pesticide contamination and residues in humans, air, water, and soils in developing countries. To assess emissions of pesticides (transport and deposition) during spray application and the risk for the human health and the environment, tracers can be useful tools. Uranine was used to quantify drift airborne and later deposition on the neighbouring field and clothes of the applicator after spraying with a knapsack sprayer in one of the biggest areas of potato production in Colombia. Keeping the same setup the amount of wet drift was measured by difference in the weight of high absorbent papers used to collect the tracer. Surprisingly this weight method (Weight-HAP) was able to explain 71% of the drift variance measured with the tracer. Therefore the weight method is presented as a suitable rapid low cost screening tool, complementary to toxicological tests, to assess air pollution, occupational and environmental exposure generated by the emissions from knapsack sprayers during pesticide application. This technique might be important in places were there is lack of analytical instruments.

  4. CANOPY STRUCTURE AND DEPOSITION EFFICIENCY OF VINEYARD SPRAYERS

    Directory of Open Access Journals (Sweden)

    Gianfranco Pergher

    2007-06-01

    Full Text Available A field study was performed to analyse how deposition efficiency from an axial-fan sprayer was affected by the canopy structure of vines trained to the High Cordon, Low Cordon and Casarsa systems, at beginning of flowering and beginning of berry touch growth stages. An empirical calibration method, providing a dose rate adjustment roughly proportional to canopy height, was used. The canopy structure was assessed using the Point Quadrat method, and determining the leaf area index (LAI and the leaf layer index (LLI. Spray deposits were measured by colorimetry, using a water soluble dye (Tartrazine as a tracer. Correlation between deposits and canopy parameters were analysed and discussed. Foliar deposits per unit leaf area were relatively constant, suggesting that empirical calibration can reduce deposit variability associated with different training systems and growth stages. Total foliar deposition ranged from 33.6% and 82.3% of total spray volume, and increased proportionally with the LLI up to LLI<4. Deposits on bunches significantly decreased with the LLI in the grape zone. The results suggest that sprayer efficiency is improved by a regular, symmetrical canopy, with few leaf layers in the grape zone as in Low Cordon. However, a LLI<3 over the whole canopy and >40% gaps in the foliage both reduced total deposition, and may increase the risk for larger drift losses.

  5. Artificial Disc Replacement

    Science.gov (United States)

    ... Spondylolisthesis BLOG FIND A SPECIALIST Treatments Artificial Disc Replacement (ADR) Patient Education Committee Jamie Baisden The disc ... Disc An artificial disc (also called a disc replacement, disc prosthesis or spine arthroplasty device) is a ...

  6. KINEMATIC STUDY OF THE AIR FLOW PRODUCED BY SOME SPRAYERS USED IN “TENDONE” VINEYARDS

    Directory of Open Access Journals (Sweden)

    Simone Pascuzzi

    2008-09-01

    Full Text Available A computerized measuring system to analyse the vector field of the air velocities in a volume surrounding the fan of air assisted sprayers usually used in tendone vineyards was designed and built. The performance of three different sprayers was tested: the first, a traditional air-convection sprayer, the other two, suitably designed for treatments in tendone vineyards. The air flow which exited through the discharge diffusers and moving towards the target sucked air from the surrounding environment that enlarged the flow rate on the target. The available flow was that which reached the vegetative and productive area, placed in a horizontal position respectively at 1.8 m and 2.0 m from the ground plane. The pneumatic sprayer produced an air flow clearly directed towards the top of the vines.

  7. Embedded computer controlled premixing inline injection system for air-assisted variable-rate sprayers

    Science.gov (United States)

    Improvements to reduce chemical waste and environmental pollution for variable-rate sprayers used in orchards and ornamental nurseries require inline injection techniques. A microprocessor controlled premixing inline injection system implementing a ceramic piston chemical metering pump and two small...

  8. Monitoring of plasma butyrylcholinesterase activity and hematological parameters in pesticide sprayers

    OpenAIRE

    Rastogi, S. K.; Singh, Vipul K.; Kesavachandran, C.; Jyoti,; Siddiqui, M. K. J.; Mathur, N.; Bharti, R. S.

    2008-01-01

    To evaluate the health impact of spraying organophosphorus insecticides (OPs), 34 male sprayers in the mango belt of Malihabad, a small town located 27 km from Lucknow in North India was selected. Plasma butyryl cholinesterase (PBChE) and complete blood count were assessed among sprayers after spraying pesticides and the findings obtained were compared with those determined in a reference group ( n = 18). The most common symptoms observed were burning sensation in the eyes (8.82%), it...

  9. Study of a test methodology to assess potential drift generated by air-assisted sprayers

    Directory of Open Access Journals (Sweden)

    Paolo Balsari

    2013-09-01

    Full Text Available During pesticide application spray drift may cause diffuse pollution phenomena in the environment. In the last years the European Union, through the Directive on the sustainable use of pesticides (128/2009 EC, has recommended the adoption of measures enabling to prevent spray drift. Among these measures, the adoption of buffer zones beside the sprayed fields requires to consider different widths for these no spray zones according to the amount of spray drift generated by the spraying equipment used for application. It is therefore necessary to classify the different sprayer models according to drift risk. For what concerns the sprayers used on arboreal crops, in order to make this classification in a simple and quick way as it was already proposed for the field crop sprayers (ISO FDIS 22369-3, a study was started aimed at defining a methodology to assess potential drift produced by the different sprayer models in absence of wind, using ad hoc test benches. On the basis of the positive first experimental data obtained, a first proposal for a new ISO standard methodology was prepared.

  10. Monitoring of plasma butyrylcholinesterase activity and hematological parameters in pesticide sprayers.

    Science.gov (United States)

    Rastogi, S K; Singh, Vipul K; Kesavachandran, C; Jyoti; Siddiqui, M K J; Mathur, N; Bharti, R S

    2008-04-01

    To evaluate the health impact of spraying organophosphorus insecticides (OPs), 34 male sprayers in the mango belt of Malihabad, a small town located 27 km from Lucknow in North India was selected. Plasma butyryl cholinesterase (PBChE) and complete blood count were assessed among sprayers after spraying pesticides and the findings obtained were compared with those determined in a reference group (n = 18). The most common symptoms observed were burning sensation in the eyes (8.82%), itching/skin irritation (23.52%) and chest symptoms (32.35%) in the exposed workers. Plasma butyrylcholinesterase (PBChE) was significantly decreased in workers. The results indicated significant decrease in the mean value of hemoglobin, hematocrit and platelets count; however, significantly higher count of leukocytes was also observed in the exposed group (sprayers) compared to that observed in the control group (P < 0.05). Monitoring of PBChE in pesticide sprayers could be useful to predict and prevent health hazards of OPs.

  11. The influence of organophosphate and carbamate on sperm chromatin and reproductive hormones among pesticide sprayers.

    Science.gov (United States)

    Jamal, Farrukh; Haque, Quazi S; Singh, Sangram; Rastogi, S K

    2016-08-01

    This study is aimed at evaluating the association between occupational exposure to organophosphate (OP) and carbamate (CB) pesticides and semen quality as well as levels of reproductive and thyroid hormones of pesticide sprayers in Malihabad, Lucknow, Uttar Pradesh, India. Thirty-five healthy men (unexposed group) and 64 male pesticide sprayers (exposed group) were recruited for clinical evaluation of fertility status. Fresh semen samples were evaluated for sperm quality and analyzed for DNA fragmentation index (DFI) by flow cytometry. Pesticide exposure was assessed by measuring erythrocyte acetylcholinesterase and plasma butyrylcholinesterase (BuChE) with a Test-mate ChE field kit. Serum levels of total testosterone (Tt), prolactin (PRL), follicle-stimulating hormone (FSH), luteinizing hormone (LH), thyroid-stimulating hormone (TSH), and free thyroxine (FT4) were analyzed using enzyme immunoassay kits. Evidence of pesticide exposure was found in 88.5% of sprayers and significant increments were observed in sperm DFI with significant decrease in some semen parameters. DFI was negatively correlated with BuChE, sperm concentration, morphology, and vitality in these pesticide sprayers. The levels of Tt, PRL, FT4, and TSH appeared to be normal; however, there was a tendency for increased LH and FSH levels in exposed workers. The results confirm the potential impact of chronic occupational exposure to OP and CB pesticides on male reproductive function, which may cause damage to sperm chromatin, decrease semen quality, and produce alterations in reproductive hormones, leading to adverse reproductive health outcomes. © The Author(s) 2015.

  12. Development of LIDAR-guided sprayer to synchronize spray outputs with canopy structures

    Science.gov (United States)

    Variable-rate application is an effective way for nursery and orchard growers to reduce pesticide use and potential contaminations to the environment. To realize this goal, an intelligent air-assisted sprayer implementing a high speed laser scanning sensor (LIDAR) was developed to vary spray output ...

  13. Light-weight extension tubes for compressed-air garden sprayers

    Science.gov (United States)

    Thomas W. McConkey; Charles E. Swett

    1967-01-01

    To hand-spray taller trees safely and efficiently, 8-, 12-, and 16-foot extension tubes for compressed-air garden sprayers were designed and built. These light-weight tubes have been used successfully for spraying white pine leaders for weevil control on the Massabesic Experimental Forest in Maine. Bill of materials and assembly instructions are included.

  14. Performance evaluation of a newly developed variable rate sprayer for nursery liner applications

    Science.gov (United States)

    An experimental variable-rate sprayer designed for liner applications was tested by comparing its spray deposit, coverage, and droplet density inside canopies of six nursery liner varieties with constant-rate applications. Spray samplers, including water sensitive papers (WSP) and nylon screens, wer...

  15. Black Hole Spin Measurement Uncertainty

    Science.gov (United States)

    Salvesen, Greg; Begelman, Mitchell C.

    2018-01-01

    Angular momentum, or spin, is one of only two fundamental properties of astrophysical black holes, and measuring its value has numerous applications. For instance, obtaining reliable spin measurements could constrain the growth history of supermassive black holes and reveal whether relativistic jets are powered by tapping into the black hole spin reservoir. The two well-established techniques for measuring black hole spin can both be applied to X-ray binaries, but are in disagreement for cases of non-maximal spin. This discrepancy must be resolved if either technique is to be deemed robust. We show that the technique based on disc continuum fitting is sensitive to uncertainties regarding the disc atmosphere, which are observationally unconstrained. By incorporating reasonable uncertainties into black hole spin probability density functions, we demonstrate that the spin measured by disc continuum fitting can become highly uncertain. Future work toward understanding how the observed disc continuum is altered by atmospheric physics, particularly magnetic fields, will further strengthen black hole spin measurement techniques.

  16. Evaluation of Three Commercial Backpack Sprayers with Aqualuer (registered trademark) 20-20 Against Caged Adult Aedes aegypti

    Science.gov (United States)

    2016-03-11

    1993. The yellow fever mosquito, Aedes aegypti. Wing Beats 5(4):4. Xue RD, Qualls WA, Smith ML, Zhao TY, Brown JR. 2012. Evaluation of Pioneer Eco...Anopheles quadrimaculatus, Aedes aegypti and Aedes albopictus . J Am Mosq Control Assoc 27:330–332. Gerberg EJ, Barnard DR, Ward RA. 1994. Manual for...Backpack sprayer and Twister XL Backpack Sprayer using Aqualuer against caged adult Aedes albopictus and Culex quinquefasciatus. J Am Mosq Control Assoc

  17. Herniated lumbar disc

    OpenAIRE

    Jordon, Jo; Konstantinou, Kika; O'Dowd, John

    2009-01-01

    Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30-50 years, with a male to female ratio of 2:1.

  18. Herniated lumbar disc

    OpenAIRE

    Jordan, Jo; Konstantinou, Kika; O'Dowd, John

    2011-01-01

    Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosis) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1.

  19. Further Evaluation of Spray Characterization of Sprayers Typically Used in Vector Control

    Science.gov (United States)

    2012-01-01

    Culex quinquefasciatus in open and vegetated terrain. J Am Mosq Control Assoc 8:69–76. Matthews GA. 1996. Application of insecticides in dengue control ...of Sprayers Typically Used in Vector Control Author(s): W. Clint Hoffmann, Todd W. Walker, Bradley K. Fritz, Muhammad Farooq, Vincent L. Smith, Cathy...A. Robinson, and Yubin Lan Source: Journal of the American Mosquito Control Association, 28(2):93-101. 2012. Published By: The American Mosquito

  20. Modelling, simulation and optimization of agricultural sprayer boom horizontal motion behaviour

    Directory of Open Access Journals (Sweden)

    Anna-Gret Borchert

    2015-08-01

    Full Text Available The study reported here presents a method offering realistic depiction of horizontal motion behaviour of agricultural sprayer booms and for reducing the extent of the simulation model involved. Additionally, various solutions of reducing boom vibrations are presented and compared with the help of simulation. Thereby is demonstrated the extent to which boom motion behaviour on booms with large working widths can be improved through passive vibration absorbers and an active vibration isolation.

  1. Increased Frequency of Rheumatoid Arthritis and Allergic Rhinitis among Pesticide Sprayers and Associations with Pesticide Use.

    Science.gov (United States)

    Koureas, Michalis; Rachiotis, George; Tsakalof, Andreas; Hadjichristodoulou, Christos

    2017-08-01

    Objective : The aim of this study was to identify diseases linked with the pesticide sprayer occupation and explore possible associations with exposure history data. Methods : Α cross sectional study was conducted among pesticide sprayers ( n = 80) and the general population ( n = 90) in Thessaly (Greece). Medical history, demographic characteristics and detailed exposure history were recorded by conducting personal interviews. Lifetime exposure indicators were calculated for several pesticide chemical subclasses. Moreover, organophosphate metabolite levels were quantified in urine samples of all participants by using gas chromatography -mass spectrometry (GC-MS). Multinomial analysis was used to determine associations between occupational pesticide exposure and diseases or disorders. Results : In the pesticide sprayers group, significantly higher frequencies for rheumatoid arthritis (RA) and allergic rhinitis were observed compared with the control group ( p = 0.002 and p = 0.024 respectively). Within the pesticide sprayers group, high lifetime pesticide exposure was associated with increased risk for reporting RA (OR: 43.07 95% CI: 3.09-600.67) and allergic rhinitis (OR: 9.72 95% CI: 2.31-40.89), compared with low pesticide exposure. Exposure to organophsphate, guanidine and quinone pesticides were associated with RA while organophosphates, pyrethroids and paraquat were associated with allergic rhinitis. Despite the higher levels of certain pesticide metabolites observed among participants with rheumatoid arthritis, the differences were not statistically significant. One metabolite (diethylthiophosphate) was found to be significantly increased in allergic rhinitis cases ( p = 0.037). Conclusion s : The results from the current study suggest a possible association of occupational pesticide exposure with RA and allergic rhinitis that should be further investigated.

  2. Increased Frequency of Rheumatoid Arthritis and Allergic Rhinitis among Pesticide Sprayers and Associations with Pesticide Use

    Directory of Open Access Journals (Sweden)

    Michalis Koureas

    2017-08-01

    Full Text Available Objective: The aim of this study was to identify diseases linked with the pesticide sprayer occupation and explore possible associations with exposure history data. Methods: Α cross sectional study was conducted among pesticide sprayers (n = 80 and the general population (n = 90 in Thessaly (Greece. Medical history, demographic characteristics and detailed exposure history were recorded by conducting personal interviews. Lifetime exposure indicators were calculated for several pesticide chemical subclasses. Moreover, organophosphate metabolite levels were quantified in urine samples of all participants by using gas chromatography -mass spectrometry (GC-MS. Multinomial analysis was used to determine associations between occupational pesticide exposure and diseases or disorders. Results: In the pesticide sprayers group, significantly higher frequencies for rheumatoid arthritis (RA and allergic rhinitis were observed compared with the control group (p = 0.002 and p = 0.024 respectively. Within the pesticide sprayers group, high lifetime pesticide exposure was associated with increased risk for reporting RA (OR: 43.07 95% CI: 3.09–600.67 and allergic rhinitis (OR: 9.72 95% CI: 2.31–40.89, compared with low pesticide exposure. Exposure to organophsphate, guanidine and quinone pesticides were associated with RA while organophosphates, pyrethroids and paraquat were associated with allergic rhinitis. Despite the higher levels of certain pesticide metabolites observed among participants with rheumatoid arthritis, the differences were not statistically significant. One metabolite (diethylthiophosphate was found to be significantly increased in allergic rhinitis cases (p = 0.037. Conclusions: The results from the current study suggest a possible association of occupational pesticide exposure with RA and allergic rhinitis that should be further investigated.

  3. Optimal Path Planning Program for Autonomous Speed Sprayer in Orchard Using Order-Picking Algorithm

    Science.gov (United States)

    Park, T. S.; Park, S. J.; Hwang, K. Y.; Cho, S. I.

    This study was conducted to develop a software program which computes optimal path for autonomous navigation in orchard, especially for speed sprayer. Possibilities of autonomous navigation in orchard were shown by other researches which have minimized distance error between planned path and performed path. But, research of planning an optimal path for speed sprayer in orchard is hardly founded. In this study, a digital map and a database for orchard which contains GPS coordinate information (coordinates of trees and boundary of orchard) and entity information (heights and widths of trees, radius of main stem of trees, disease of trees) was designed. An orderpicking algorithm which has been used for management of warehouse was used to calculate optimum path based on the digital map. Database for digital map was created by using Microsoft Access and graphic interface for database was made by using Microsoft Visual C++ 6.0. It was possible to search and display information about boundary of an orchard, locations of trees, daily plan for scattering chemicals and plan optimal path on different orchard based on digital map, on each circumstance (starting speed sprayer in different location, scattering chemicals for only selected trees).

  4. Field sprayer for inter and intra-row weed control: performance and labor savings

    Directory of Open Access Journals (Sweden)

    J. Carballido

    2013-07-01

    Full Text Available Studies of new tools and methods for weed control have been motivated by increased consumer demand for organic produce, consumer and regulatory demands for a reduction in environmentally harmful herbicide use, and the decreased availability of farm workers willing to perform manual tasks, such as hand weeding. This study describes the performance of a new sprayer system for commercial production that integrates two herbicide applications in a single pass, selective herbicide (SH application in narrow bands over the crop row, and a non-selective herbicide (NSH application between crop rows. A real-time kinematic (RTK global positioning system (GPS was used for auto-guidance in seeding and spraying operations. Conventional broadcast SHs and experimental treatments were applied at a constant nominal speed of 5.5 km h-1 for comparison. Trials in commercial sugar beet fields demonstrated the following: (i average hand-weeding time can be reduced by 53% (ii the new sprayer system reduced SH use by 76%, and (iii sugar beet density did not change significantly during treatment. These results demonstrate the feasibility of using the new RTK-GPS controller sprayer system for differential and efficient herbicide application in inter- and intra-row zones in row crop production.

  5. On the diversity and statistical properties of protostellar discs

    Science.gov (United States)

    Bate, Matthew R.

    2018-04-01

    We present results from the first population synthesis study of protostellar discs. We analyse the evolution and properties of a large sample of protostellar discs formed in a radiation hydrodynamical simulation of star cluster formation. Due to the chaotic nature of the star formation process, we find an enormous diversity of young protostellar discs, including misaligned discs, and discs whose orientations vary with time. Star-disc interactions truncate discs and produce multiple systems. Discs may be destroyed in dynamical encounters and/or through ram-pressure stripping, but reform by later gas accretion. We quantify the distributions of disc mass and radii for protostellar ages up to ≈105 yr. For low-mass protostars, disc masses tend to increase with both age and protostellar mass. Disc radii range from of order 10 to a few hundred au, grow in size on time-scales ≲ 104 yr, and are smaller around lower mass protostars. The radial surface density profiles of isolated protostellar discs are flatter than the minimum mass solar nebula model, typically scaling as Σ ∝ r-1. Disc to protostar mass ratios rarely exceed two, with a typical range of Md/M* = 0.1-1 to ages ≲ 104 yr and decreasing thereafter. We quantify the relative orientation angles of circumstellar discs and the orbit of bound pairs of protostars, finding a preference for alignment that strengths with decreasing separation. We also investigate how the orientations of the outer parts of discs differ from the protostellar and inner disc spins for isolated protostars and pairs.

  6. The slaved disc model for SS 433

    International Nuclear Information System (INIS)

    Whitmire, D.P.; Matese, J.J.

    1980-01-01

    A slaved disc model for SS 433 is investigated in which the beams originate normal to the surface of an accretion disc around a compact object in a binary system. The 13-day period in the 'stationary' system of lines is assumed to be associated with binary orbital motion and the 164-day periodicity in the moving line system is identified with disc precession. As in the slaved disc model for Her X-1, it is assumed that material is processed through the disc rapidly (relative to 164 days) so that the disc precesses at the same rate as the spin axis of the secondary which is driven by the gravitational torque applied by the compact object. If the secondary star does not underfill its critical lobe then the apparent absence of X-ray or optical eclipsing and beam interruption by the secondary places severe constraints on the model. It is shown that the viability of the basic model requires that the mass of the compact object be approximately > 10 times the mass of the secondary. Thus if the slaved disc model is applicable to SS 433 and if the mass of the secondary is approximately > 1 solar mass it follows that the compact object is a massive black hole. (author)

  7. Development and evaluation of a targeted orchard sprayer using machine vision technology

    Directory of Open Access Journals (Sweden)

    H Asaei

    2016-09-01

    Full Text Available Introduction In conventional methods of spraying in orchards, the amount of pesticide sprayed, is not targeted. The pesticide consumption data indicates that the application rate of pesticide in greenhouses and orchards is more than required. Less than 30% of pesticide sprayed actually reaches nursery canopies while the rest are lost and wasted. Nowadays, variable rate spray applicators using intelligent control systems can greatly reduce pesticide use and off-target contamination of environment in nurseries and orchards. In this research a prototype orchard sprayer based on machine vision technology was developed and evaluated. This sprayer performs real-time spraying based on the tree canopy structure and its greenness extent which improves the efficiency of spraying operation in orchards. Materials and Methods The equipment used in this study comprised of three main parts generally: 1- Mechanical Equipment 2- Data collection and image processing system 3- Electronic control system Two booms were designed to support the spray nozzles and to provide flexibility in directing the spray nozzles to the target. The boom comprised two parts, the vertical part and inclined part. The vertical part of the boom was used to spray one side of the trees during forward movement of the tractor and inclined part of the boom was designed to spray the upper half of the tree canopy. Three nozzles were considered on each boom. On the vertical part of the boom, two nozzles were placed, whereas one other nozzle was mounted on the inclined part of the boom. To achieve different tree heights, the vertical part of the boom was able to slide up and down. Labview (version 2011 was used for real time image processing. Images were captured through RGB cameras mounted on a horizontal bar attached on top of the tractor to take images separately for each side of the sprayer. Images were captured from the top of the canopies looking downward. The triggering signal for

  8. Desain dan Pengujian Prototipe Sistem Kontrol Mesin Sprayer Dosis Variabel untuk Aplikasi Penyemprotan Pertanian Presisi

    Directory of Open Access Journals (Sweden)

    Muhammad Rizal

    2016-10-01

    Full Text Available Presently. Rise of crop production often face major obstacle, such as plant disease and pests.Crop losses can occur when plant disease and pests are not treated properly. However, excessive use of chemical pesticide cause environmental damage.The objective of present study was to develop and evaluate control system of variable rate sprayer and its performance for precision farming. The methods consist of some sequential steps i.e. measuring disease and pest intensity and determine its respective dose then input it in microcontroller grid sequence; controlling several sprayer components, i.e. pump motor, solenoid valve, and proximity sensor for plant detection; and conducting performance test of sprayer prototype based on microcontroller data input. The results showed that in order to obtain appropriate flow rate correspond to disease and pest intensity, a PWM (pulse width modulation ranged of 100-250, 217-592 rpm of motor speed, 2-10 sec/plant of spray duration, and 4-11 ml/s of flow rate, were used. The field test with data input, i.e. 120 plants, with 8.1% and 15.5% of disease intensity, 10 and 8.3 ml/sec/row (10m/row, and 20 and 60 sec/plant of spray duration; generated average actual results with 10.2 and 7.8 ml/sec/row of flow rate and 23.2 and 64.3 sec/plant of spray duration. The field test also indicates 91% of precision time of application.

  9. Methodology for the Regulation of Boom Sprayers Operating in Circular Trajectories

    Directory of Open Access Journals (Sweden)

    Alfredo Serreta

    2011-04-01

    Full Text Available A methodology for the regulation of boom sprayers working in circular trajectories has been developed. In this type of trajectory, the areas of the plots of land treated by the outer nozzles of the boom are treated at reduced rates, and those treated by the inner nozzles are treated in excess. The goal of this study was to establish the methodology to determine the flow of the individual nozzles on the boom to guarantee that the dose of the product applied per surface unit is similar across the plot. This flow is a function of the position of the equipment (circular trajectory radius and of the displacement velocity such that the treatment applied per surface unit is uniform. GPS technology was proposed as a basis to establish the position and displacement velocity of the tractor. The viability of this methodology was simulated considering two circular plots with radii of 160 m and 310 m, using three sets of equipment with boom widths of 14.5, 24.5 and 29.5 m. Data showed as increasing boom widths produce bigger errors in the surface dose applied (L/m2. Error also increases with decreasing plot surface. As an example, considering the three boom widths of 14.5, 24.5 and 29.5 m working on a circular plot with a radius of 160 m, the percentage of surface with errors in the applied surface dose greater than 5% was 30%, 58% and 65% respectively. Considering a circular plot with radius of 310 m the same errors were 8%, 22% and 31%. To obtain a uniform superficial dose two sprayer regulation alternatives have been simulated considering a 14.5 m boom: the regulation of the pressure of each nozzle and the regulation of the pressure of each boom section. The viability of implementing the proposed methodology on commercial boom sprayers using GPS antennas to establish the position and displacement velocity of the tractor was justified with a field trial in which a self-guiding commercial GPS system was used along with three precision GPS systems located in

  10. Formation of precessing jets by tilted black hole discs in 3D general relativistic MHD simulations

    Science.gov (United States)

    Liska, M.; Hesp, C.; Tchekhovskoy, A.; Ingram, A.; van der Klis, M.; Markoff, S.

    2018-02-01

    Gas falling into a black hole (BH) from large distances is unaware of BH spin direction, and misalignment between the accretion disc and BH spin is expected to be common. However, the physics of tilted discs (e.g. angular momentum transport and jet formation) is poorly understood. Using our new GPU-accelerated code H-AMR, we performed 3D general relativistic magnetohydrodynamic simulations of tilted thick accretion discs around rapidly spinning BHs, at the highest resolution to date. We explored the limit where disc thermal pressure dominates magnetic pressure, and showed for the first time that, for different magnetic field strengths on the BH, these flows launch magnetized relativistic jets propagating along the rotation axis of the tilted disc (rather than of the BH). If strong large-scale magnetic flux reaches the BH, it bends the inner few gravitational radii of the disc and jets into partial alignment with the BH spin. On longer time-scales, the simulated disc-jet system as a whole undergoes Lense-Thirring precession and approaches alignment, demonstrating for the first time that jets can be used as probes of disc precession. When the disc turbulence is well resolved, our isolated discs spread out, causing both the alignment and precession to slow down.

  11. Herniated Cervical Disc

    Science.gov (United States)

    ... and inflammation that occur as a result of disc herniation. These include aspirin, ibuprofen, naproxen and a variety ... many factors including the exact location of the disc herniation and the experience and preference of the surgeon. ...

  12. Radially truncated galactic discs

    NARCIS (Netherlands)

    Grijs, R. de; Kregel, M.; Wesson, K H

    2000-01-01

    Abstract: We present the first results of a systematic analysis of radially truncatedexponential discs for four galaxies of a sample of disc-dominated edge-onspiral galaxies. Edge-on galaxies are very useful for the study of truncatedgalactic discs, since we can follow their light distributions out

  13. Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

    Directory of Open Access Journals (Sweden)

    Ramon Salcedo

    2015-06-01

    Full Text Available Atmospheric drift of plant protection products is considered a major source of air pollution during pesticide applications. Citrus protection against pests and diseases usually requires application of these products using air-blast sprayers. Many authors have emphasized the influence of vegetation on the risk of spray drift. The aim of this work was to describe in detail how the airflow from an air-blast sprayer behaves when it reaches citrus trees and, in particular, the effect that the tree canopy has on this flow. Tests were conducted at a commercial citrus orchard with conventional machinery, placed parallel to a row of trees. Air velocity and direction was measured using a 3D ultrasonic anemometer in 225 points situated in three parallel planes perpendicular to the equipment. The stability of the airflow at each measuring point was studied and the mean velocities were graphically represented. Two vortexes, one behind the canopy, and another over the tree, have been deducted and never been reported before. Both may have an important influence on the trajectories of the sprayed droplets and, as a consequence, on the way in which plant protection products are diffused into the atmosphere. Observed turbulence intensities were higher than in similar experiments conducted in other tree crops, which may be attributable to the higher air volume generated by the machinery used for citrus protection and to the higher foliage density of citrus orchards.

  14. Description of the airflow produced by an air-assisted sprayer during pesticide applications to citrus

    Energy Technology Data Exchange (ETDEWEB)

    Salcedo, R.; Garcera, C.; Granell, R.; Molto, E.; Chueca, P.

    2015-07-01

    Atmospheric drift of plant protection products is considered a major source of air pollution during pesticide applications. Citrus protection against pests and diseases usually requires application of these products using air-blast sprayers. Many authors have emphasized the influence of vegetation on the risk of spray drift. The aim of this work was to describe in detail how the airflow from an air-blast sprayer behaves when it reaches citrus trees and, in particular, the effect that the tree canopy has on this flow. Tests were conducted at a commercial citrus orchard with conventional machinery, placed parallel to a row of trees. Air velocity and direction was measured using a 3D ultrasonic anemometer in 225 points situated in three parallel planes perpendicular to the equipment. The stability of the airflow at each measuring point was studied and the mean velocities were graphically represented. Two vortexes, one behind the canopy, and another over the tree, have been deducted and never been reported before. Both may have an important influence on the trajectories of the sprayed droplets and, as a consequence, on the way in which plant protection products are diffused into the atmosphere. Observed turbulence intensities were higher than in similar experiments conducted in other tree crops, which may be attributable to the higher air volume generated by the machinery used for citrus protection and to the higher foliage density of citrus orchards. (Author)

  15. HRI usability evaluation of interaction modes for a teleoperated agricultural robotic sprayer.

    Science.gov (United States)

    Adamides, George; Katsanos, Christos; Parmet, Yisrael; Christou, Georgios; Xenos, Michalis; Hadzilacos, Thanasis; Edan, Yael

    2017-07-01

    Teleoperation of an agricultural robotic system requires effective and efficient human-robot interaction. This paper investigates the usability of different interaction modes for agricultural robot teleoperation. Specifically, we examined the overall influence of two types of output devices (PC screen, head mounted display), two types of peripheral vision support mechanisms (single view, multiple views), and two types of control input devices (PC keyboard, PS3 gamepad) on observed and perceived usability of a teleoperated agricultural sprayer. A modular user interface for teleoperating an agricultural robot sprayer was constructed and field-tested. Evaluation included eight interaction modes: the different combinations of the 3 factors. Thirty representative participants used each interaction mode to navigate the robot along a vineyard and spray grape clusters based on a 2 × 2 × 2 repeated measures experimental design. Objective metrics of the effectiveness and efficiency of the human-robot collaboration were collected. Participants also completed questionnaires related to their user experience with the system in each interaction mode. Results show that the most important factor for human-robot interface usability is the number and placement of views. The type of robot control input device was also a significant factor in certain dependents, whereas the effect of the screen output type was only significant on the participants' perceived workload index. Specific recommendations for mobile field robot teleoperation to improve HRI awareness for the agricultural spraying task are presented. Copyright © 2017 Elsevier Ltd. All rights reserved.

  16. Influence of travel speed on spray deposition uniformity from an air-assisted variable-rate sprayer

    Science.gov (United States)

    A newly developed LiDAR-guided air-assisted variable-rate sprayer for nursery and orchard applications was tested at various travel speeds to compare its spray deposition and coverage uniformity with constant-rate applications. Spray samplers, including nylon screens and water-sensitive papers (WSP)...

  17. Instability of warped discs

    Science.gov (United States)

    Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.

    2018-01-01

    Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which in general yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term which would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.

  18. Lumbar intervertebral disc abnormalities: comparison of quantitative T2 mapping with conventional MR at 3.0 T

    Energy Technology Data Exchange (ETDEWEB)

    Trattnig, Siegfried [Medical University of Vienna, Department of Radiology, MR Centre-Highfield MR, Vienna (Austria); Ludwig Boltzmann Institute for Clinical and Experimental Traumatology, Austrian Cluster for Tissue Regeneration, Vienna (Austria); Stelzeneder, David; Goed, Sabine; Reissegger, Michael [Medical University of Vienna, Department of Radiology, MR Centre-Highfield MR, Vienna (Austria); Mamisch, Tallal C. [Inselspital Berne, Orthopedic Surgery Department, Berne (Switzerland); Paternostro-Sluga, Tatjana [Medical University of Vienna, Department of Physical Medicine and Rehabilitation, Vienna (Austria); Weber, Michael [Medical University of Vienna, Department of Radiology, Vienna (Austria); Szomolanyi, Pavol [Medical University of Vienna, Department of Radiology, MR Centre-Highfield MR, Vienna (Austria); Slovak Academy of Sciences, Department of Imaging Methods, Institute of Measurement Science, Bratislava (Slovakia); Welsch, Goetz H. [Medical University of Vienna, Department of Radiology, MR Centre-Highfield MR, Vienna (Austria); University Hospital of Erlangen, Department of Trauma Surgery, Erlangen (Germany)

    2010-11-15

    To assess the relationship of morphologically defined lumbar disc abnormalities with quantitative T2 mapping. Fifty-three patients, mean age 39 years, with low back pain were examined by MRI at 3 T (sagittal T1-fast spin echo (FSE), three-plane T2-FSE for morphological MRI, multi-echo spin echo for T2 mapping). All discs were classified morphologically. Regions of interest (ROIs) for the annulus were drawn. The space in between was defined as the nucleus pulposus (NP). To evaluate differences between the classified groups, univariate ANOVA with post hoc Games-Howell and paired two-tailed t tests were used. In 265 discs we found 39 focal herniations, 10 annular tears, 123 bulging discs and 103 ''normal discs''. T2 values of the NP between discs with annular tear and all other groups were statistically significantly different (all p {<=} 0.01). Discs with annular tears showed markedly lower NP T2 values than discs without. The difference in NP T2 values between discs with focal herniation and normal discs (p = 0.005) was statistically significant. There was no difference in NP T2 values between bulging and herniated discs (p = 0.11) Quantitative T2 mapping of the nucleus pulposus of the intervertebral disc in the lumbar spine at 3 T reveals significant differences in discs with herniation and annular tears compared with discs without these abnormalities. (orig.)

  19. Mechanical deformation and glycosaminoglycan content changes in a rabbit annular puncture disc degeneration model.

    Science.gov (United States)

    Chan, Deva D; Khan, Safdar N; Ye, Xiaojing; Curtiss, Shane B; Gupta, Munish C; Klineberg, Eric O; Neu, Corey P

    2011-08-15

    Evaluation of degenerated intervertebral discs from a rabbit annular puncture model by using specialized magnetic resonance imaging (MRI) techniques, including displacement encoding with stimulated echoes and a fast-spin echo (DENSE-FSE) acquisition and delayed gadolinium-enhanced MRI of cartilage (dGEMRIC). To evaluate a rabbit disc degeneration model by using various MRI techniques. To determine the displacements and strains, spin-lattice relaxation time (T1), and glycosaminoglycan (GAG) distribution of degenerated discs as compared to normal and adjacent level discs. Annular puncture of the intervertebral disc produces disc degeneration in rabbits. DENSE-FSE has been previously demonstrated in articular cartilage for the measurement of soft tissue displacements and strains. MRI also can measure the T1 of tissue, and dGEMRIC can quantify GAG concentration in cartilage. METHODS.: In eight New Zealand white rabbits, the annulus fibrosis of a lumbar disc was punctured. After 4 weeks, the punctured and cranially adjacent motion segments were isolated for MRI and histology. MRI was used to estimate the disc volume and map T1. DENSE-FSE was used to determine displacements for the estimation of strains. dGEMRIC was then used to determine GAG distributions. Histology and standard MRI indicated degeneration in punctured discs. Disc volume increased significantly at 4 weeks after the puncture. Displacement of the nucleus pulposus was distinct from that of the annulus fibrosis in most untreated discs but not in punctured discs. T1 was significantly higher and GAG concentration significantly lower in punctured discs compared with untreated adjacent level discs. Noninvasive and quantitative MRI techniques can be used to evaluate the mechanical and biochemical changes that occur with animal models of disc degeneration. DENSE-FSE, dGEMRIC, and similar techniques have potential for evaluating the progression of disc degeneration and the efficacy of treatments.

  20. Molecular detection of M. tuberculosis and M. bovis and hematological and biochemical analyses in agricultural sprayers exposed to pesticides: A cross-sectional study in Punjab, Pakistan during 2014-2016.

    Science.gov (United States)

    Riaz, Saffora; Manzoor, Farkhanda; Mahmood, Nasir; Shahid, Saman

    2017-07-01

    We determined the correlation between a pesticide exposure, physical health and susceptibility toward tuberculosis along with hematological indices and liver enzymes' alterations in sprayers exposed to pesticides. Molecular detection of Mycobacterium tuberculosis and Mycobacterium bovis was detected by targeting histone-like protein (hupB) gene. The WBC (white blood cells) and RBC (red blood cells) levels of male sprayers and non-sprayers were significantly different (P<0.05). In female spray workers, the WBC and neutrophils levels were significantly different as compared with non-sprayers. Overall, in both male and female pesticide-exposed sprayers, mean values of alanine amino transferase and aspartate amino transferase were higher as compared with unexposed workers. M. Tuberculosis were detected in 15% male sprayers and 36% female sprayers while, M. bovis was detected in 5% male sprayers and 10% female sprayers. A χ 2 -test indicated that there existed a significant different (P<0.05) between positive and negative M. tuberculosis and M. bovis in both male/female spray workers out of total. The susceptibility of pesticide-exposed sprayers to tuberculosis and alterations in hematology and liver enzymes is crucial for health. Toxic effects of pesticides may lead to a weak immune system and increased tuberculosis susceptibility.

  1. Instability of warped discs

    Science.gov (United States)

    Doǧan, S.; Nixon, C. J.; King, A. R.; Pringle, J. E.

    2018-05-01

    Accretion discs are generally warped. If a warp in a disc is too large, the disc can `break' apart into two or more distinct planes, with only tenuous connections between them. Further, if an initially planar disc is subject to a strong differential precession, then it can be torn apart into discrete annuli that precess effectively independently. In previous investigations, torque-balance formulae have been used to predict where and when the disc breaks into distinct parts. In this work, focusing on discs with Keplerian rotation and where the shearing motions driving the radial communication of the warp are damped locally by turbulence (the `diffusive' regime), we investigate the stability of warped discs to determine the precise criterion for an isolated warped disc to break. We find and solve the dispersion relation, which, in general, yields three roots. We provide a comprehensive analysis of this viscous-warp instability and the emergent growth rates and their dependence on disc parameters. The physics of the instability can be understood as a combination of (1) a term that would generally encapsulate the classical Lightman-Eardley instability in planar discs (given by ∂(νΣ)/∂Σ < 0) but is here modified by the warp to include ∂(ν1|ψ|)/∂|ψ| < 0, and (2) a similar condition acting on the diffusion of the warp amplitude given in simplified form by ∂(ν2|ψ|)/∂|ψ| < 0. We discuss our findings in the context of discs with an imposed precession, and comment on the implications for different astrophysical systems.

  2. Disc operational system

    International Nuclear Information System (INIS)

    Veretenov, V.Yu.; Volkov, A.I.; Gurevich, M.I.; Kozik, V.S.; Pod'yachev, E.I.; Shapiro, M.L.

    1974-01-01

    A disc operational system is proposed, which is based on the file structure and designed for use in a BESM-6 computer with the software system comprising a dispatcher DD-73 and a monitor 'Dubna'. The main distinguishing feature of the disc operational system is the decentralization of the file system. Each disc package is an independent file unaffected by the state of the other disc packages. The use of several disc packages is allowed. The above feature of the disc operational system makes it possible to simplify the language of communication with the system, to give the user the opportunity of controlling the file quite independently, and to simplify the maintenance of the discs by the computer personnel. One and the same disc can be simultaneously addressed by all problems in the processor (both mathematical and service). A single file, however, may be used in the recording mode by only one problem. The description presented is the instruction for users. It also describes special possibilities open to the system programmers [ru

  3. Intratracheal Seal Disc

    DEFF Research Database (Denmark)

    Christiansen, Karen J; Moeslund, Niels; Lauridsen, Henrik

    2017-01-01

    21, CT was repeated before euthanasia. The trachea and epidermis were excised en bloc for histopathological evaluation. RESULTS: Insertion and correct placement of the disc was unproblematic in all animals. CT at day 14 confirmed a clear airway, appropriate placement of the disc, and full closure...

  4. Evaluation of interferon-γ and interlukin -12 in sera of pesticides sprayers with or without hepatitis c virus

    International Nuclear Information System (INIS)

    Abdelgawad, M.R.; Wahba, M.; Abdel-Wahab, M.

    2010-01-01

    Both infection with HCV and exposure to pesticides in both developing and developed countries constitutes a major problem indicating severe modulation of the immune system. The present study demonstrated that, the levels of IL-12 and AFP were significantly elevated in pesticide sprayers especially in those who were infected with HCV. Otherwise, the serum level of IFN-γ was decreased in pesticide sprayers especially in those infected with HCV. In addition , liver function tests, blood picture and levels of ammonia and urea were deteriorated in pesticide sprayers especially in those infected with HCV compared with that of the control group. IL-12 and IFN-γ are two important cytokines that play an important role in the immune functions and are considered as indicators of cellular and humoral immune responses and it may be concluded that IFN-γ and IL-12 may play a possible role of pesticides exposure as a risk factor for hepatocellular carcinogenesis especially in the presence of concurrent hepatitis C virus (HCV) infection.

  5. Utilizing a Robotic Sprayer for High Lateral and Mass Resolution MALDI FT-ICR MSI of Microbial Cultures

    Energy Technology Data Exchange (ETDEWEB)

    Anderton, Christopher R.; Chu, Rosalie K.; Tolic, Nikola; Creissen, Alain V.; Pasa-Tolic, Ljiljana

    2016-01-07

    The ability to visualize biochemical interactions between microbial communities using MALDI MSI has provided tremendous insights into a variety of biological fields. Matrix application using a sieve proved to be incredibly useful, but it had many limitations that include uneven matrix coverage and limitation in the types of matrices one could employ in their studies. Recently, there has been a concerted effort to improve matrix application for studying agar plated microbial cultures, many of which utilized automated matrix sprayers. Here, we describe the usefulness of using a robotic sprayer for matrix application. The robotic sprayer has two-dimensional control over where matrix is applied and a heated capillary that allows for rapid drying of the applied matrix. This method provided a significant increase in MALDI sensitivity over the sieve method, as demonstrated by FT-ICR MS analysis, facilitating the ability to gain higher lateral resolution MS images of Bacillus Subtilis than previously reported. This method also allowed for the use of different matrices to be applied to the culture surfaces.

  6. Analysis of the air flow generated by an air-assisted sprayer equipped with two axial fans using a 3D sonic anemometer.

    Science.gov (United States)

    García-Ramos, F Javier; Vidal, Mariano; Boné, Antonio; Malón, Hugo; Aguirre, Javier

    2012-01-01

    The flow of air generated by a new design of air assisted sprayer equipped with two axial fans of reversed rotation was analyzed. For this goal, a 3D sonic anemometer has been used (accuracy: 1.5%; measurement range: 0 to 45 m/s). The study was divided into a static test and a dynamic test. During the static test, the air velocity in the working vicinity of the sprayer was measured considering the following machine configurations: (1) one activated fan regulated at three air flows (machine working as a traditional sprayer); (2) two activated fans regulated at three air flows for each fan. In the static test 72 measurement points were considered. The location of the measurement points was as follow: left and right sides of the sprayer; three sections of measurement (A, B and C); three measurement distances from the shaft of the machine (1.5 m, 2.5 m and 3.5 m); and four measurement heights (1 m, 2 m, 3 m and 4 m). The static test results have shown significant differences in the module and the vertical angle of the air velocity vector in function of the regulations of the sprayer. In the dynamic test, the air velocity was measured at 2.5 m from the axis of the sprayer considering four measurement heights (1 m, 2 m, 3 m and 4 m). In this test, the sprayer regulations were: one or two activated fans; one air flow for each fan; forward speed of 2.8 km/h. The use of one fan (back) or two fans (back and front) produced significant differences on the duration of the presence of wind in the measurement point and on the direction of the air velocity vector. The module of the air velocity vector was not affected by the number of activated fans.

  7. Analysis of the Air Flow Generated by an Air-Assisted Sprayer Equipped with Two Axial Fans Using a 3D Sonic Anemometer

    Directory of Open Access Journals (Sweden)

    Javier Aguirre

    2012-06-01

    Full Text Available The flow of air generated by a new design of air assisted sprayer equipped with two axial fans of reversed rotation was analyzed. For this goal, a 3D sonic anemometer has been used (accuracy: 1.5%; measurement range: 0 to 45 m/s. The study was divided into a static test and a dynamic test. During the static test, the air velocity in the working vicinity of the sprayer was measured considering the following machine configurations: (1 one activated fan regulated at three air flows (machine working as a traditional sprayer; (2 two activated fans regulated at three air flows for each fan. In the static test 72 measurement points were considered. The location of the measurement points was as follow: left and right sides of the sprayer; three sections of measurement (A, B and C; three measurement distances from the shaft of the machine (1.5 m, 2.5 m and 3.5 m; and four measurement heights (1 m, 2 m, 3 m and 4 m. The static test results have shown significant differences in the module and the vertical angle of the air velocity vector in function of the regulations of the sprayer. In the dynamic test, the air velocity was measured at 2.5 m from the axis of the sprayer considering four measurement heights (1 m, 2 m, 3 m and 4 m. In this test, the sprayer regulations were: one or two activated fans; one air flow for each fan; forward speed of 2.8 km/h. The use of one fan (back or two fans (back and front produced significant differences on the duration of the presence of wind in the measurement point and on the direction of the air velocity vector. The module of the air velocity vector was not affected by the number of activated fans.

  8. Optic disc oedema

    DEFF Research Database (Denmark)

    Nielsen, Marianne Kromann; Hamann, Steffen

    2014-01-01

    Optic disc oedema describes the nonspecific, localized swelling of the optic nerve head regardless of aetiology. Therefore, differentiating among the various aetiologies depends on a thorough history and knowledge of the clinical characteristics of the underlying conditions. Papilloedema strictly...... refers to optic disc oedema as a consequence of elevated intracranial pressure. It is usually a bilateral condition and visual function is preserved until late. Optic disc oedema caused by an anterior optic neuropathy is usually unilateral and accompanied by the loss of visual function....

  9. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2012-01-01

    In a new branch of physics and technology called spin-electronics or spintronics, the flow of electrical charge (usual current) as well as the flow of electron spin, the so-called 'spin current', are manipulated and controlled together. This book provides an introduction and guide to the new physics and application of spin current.

  10. Droplets spectrum of air-assisted boom sprayers under different environmental and operational conditions

    Directory of Open Access Journals (Sweden)

    Robson S. Sasaki

    2016-01-01

    Full Text Available ABSTRACT During pesticide spraying, the psychrometric conditions of the air may cause evaporation of the droplets along their trajectory from the nozzle to the target. Thus, this study aimed to evaluate the effect of air psychrometric conditions and operating pressure on the droplet spectrum of air-assisted boom sprayers. The test was performed using a prototype equipped with an axial fan, a flow homogenizer, temperature and relative air humidity sensors, a spray nozzle and a gas-heating system to warm up the airflow. With the assembled system and the aid of a particle analyser, the JSF 11002 spray nozzle was evaluated with respect to droplet spectrum in four air psychrometric conditions (7, 14, 21 and 28 hPa and at four operating pressures (200, 300, 400 and 500 kPa. At the end, evaporation losses were observed during the sprayings. For a given operating pressure and for each increment of 1 hPa in vapor pressure deficit, there was a diameter reduction of approximately 0.0759, 0.518 and 1.514 μm for the parameters DV0.1, DV0.5 and DV0.9, respectively. The diameter of the droplets decreased as the operating pressure increased.

  11. Cover layer technology and a new hard coat for cartridge-free Blu-ray disc

    Science.gov (United States)

    Kang, Tae-Sik; Han, Mi Young; Lee, Seong-Keun; Jang, Sung Hoon; Hong, Young Jun; Seo, Hun; Lee, Chang-Ho

    2004-09-01

    Spin coating method for cover layer of Blu-ray Disc (BD) has been studied and a new hard coat resin including antifouling property has been developed. A vacuum chuck was newly designed to minimize the ski-jump effect. 3 mm hard coat layer was stacked onto the 97 mm cover layer by spin coating method.

  12. Validation of a CFD model by using 3D sonic anemometers to analyse the air velocity generated by an air-assisted sprayer equipped with two axial fans.

    Science.gov (United States)

    García-Ramos, F Javier; Malón, Hugo; Aguirre, A Javier; Boné, Antonio; Puyuelo, Javier; Vidal, Mariano

    2015-01-22

    A computational fluid dynamics (CFD) model of the air flow generated by an air-assisted sprayer equipped with two axial fans was developed and validated by practical experiments in the laboratory. The CFD model was developed by considering the total air flow supplied by the sprayer fan to be the main parameter, rather than the outlet air velocity. The model was developed for three air flows corresponding to three fan blade settings and assuming that the sprayer is stationary. Actual measurements of the air velocity near the sprayer were taken using 3D sonic anemometers. The workspace sprayer was divided into three sections, and the air velocity was measured in each section on both sides of the machine at a horizontal distance of 1.5, 2.5, and 3.5 m from the machine, and at heights of 1, 2, 3, and 4 m above the ground The coefficient of determination (R2) between the simulated and measured values was 0.859, which demonstrates a good correlation between the simulated and measured data. Considering the overall data, the air velocity values produced by the CFD model were not significantly different from the measured values.

  13. Validation of a CFD Model by Using 3D Sonic Anemometers to Analyse the Air Velocity Generated by an Air-Assisted Sprayer Equipped with Two Axial Fans

    Directory of Open Access Journals (Sweden)

    F. Javier García-Ramos

    2015-01-01

    Full Text Available A computational fluid dynamics (CFD model of the air flow generated by an air-assisted sprayer equipped with two axial fans was developed and validated by practical experiments in the laboratory. The CFD model was developed by considering the total air flow supplied by the sprayer fan to be the main parameter, rather than the outlet air velocity. The model was developed for three air flows corresponding to three fan blade settings and assuming that the sprayer is stationary. Actual measurements of the air velocity near the sprayer were taken using 3D sonic anemometers. The workspace sprayer was divided into three sections, and the air velocity was measured in each section on both sides of the machine at a horizontal distance of 1.5, 2.5, and 3.5 m from the machine, and at heights of 1, 2, 3, and 4 m above the ground The coefficient of determination (R2 between the simulated and measured values was 0.859, which demonstrates a good correlation between the simulated and measured data. Considering the overall data, the air velocity values produced by the CFD model were not significantly different from the measured values.

  14. Pseudoenhancement of intervertebral disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Araki, Y.; Ootani, M.; Furukawa, T.; Tsukaguchi, I. (Dept. of Radiology, Osaka Rosai Hospital (Japan)); Mitomo, M. (Dept. of Radiology, Osaka Univ. Medical School (Japan))

    1992-08-01

    Two patients with intervertebral disc herniation appeared to demonstrate abnormally diffuse and intense enhancement of the disc after intravenous administration of gadolinium-DTPA for MRI. Surgery disclosed a dilated epidural venous plexus in one and vascular granulation tissue in the other, associated with the herniated disc material. The mechanism of this 'pseudoenhancement' of the disc appears to be a partial volume effect of disc material and the adjacent veins or granulation tissue. Pseudoenhancement of a herniated disc should be included in the differential diagnosis of a diffusely enhancing epidural mass. (orig.).

  15. A homopolar disc dynamo experiment with liquid metal contacts

    OpenAIRE

    Avalos-Zúñiga, R. A.; Priede, J.; Bello-Morales, C. E.

    2017-01-01

    We present experimental results of a homopolar disc dynamo constructed at CICATA-Quer\\'etaro in Mexico. The device consists of a flat, multi-arm spiral coil which is placed above a fast-spinning metal disc and connected to the latter by sliding liquid-metal electrical contacts. Theoretically, self-excitation of the magnetic field is expected at the critical magnetic Reynolds number Rm~45, which corresponds to a critical rotation rate of about 10 Hz. We measured the magnetic field above the di...

  16. Line-driven ablation of circumstellar discs - I. Optically thin decretion discs of classical Oe/Be stars.

    Science.gov (United States)

    Kee, Nathaniel Dylan; Owocki, Stanley; Sundqvist, J O

    2016-05-21

    The extreme luminosities of massive, hot OB stars drive strong stellar winds through line-scattering of the star's UV continuum radiation. For OB stars with an orbiting circumstellar disc, we explore here the effect of such line-scattering in driving an ablation of material from the disc's surface layers, with initial focus on the marginally optically thin decretion discs of classical Oe and Be stars. For this we apply a multidimensional radiation-hydrodynamics code that assumes simple optically thin ray tracing for the stellar continuum, but uses a multiray Sobolev treatment of the line transfer; this fully accounts for the efficient driving by non-radial rays, due to desaturation of line-absorption by velocity gradients associated with the Keplerian shear in the disc. Results show a dense, intermediate-speed surface ablation, consistent with the strong, blueshifted absorption of UV wind lines seen in Be shell stars that are observed from near the disc plane. A key overall result is that, after an initial adjustment to the introduction of the disc, the asymptotic disc destruction rate is typically just an order-unity factor times the stellar wind mass-loss rate. For optically thin Be discs, this leads to a disc destruction time of order months to years, consistent with observationally inferred disc decay times. The much stronger radiative forces of O stars reduce this time to order days, making it more difficult for decretion processes to sustain a disc in earlier spectral types, and so providing a natural explanation for the relative rarity of Oe stars in the Galaxy. Moreover, the decrease in line-driving at lower metallicity implies both a reduction in the winds that help spin-down stars from near-critical rotation, and a reduction in the ablation of any decretion disc; together these provide a natural explanation for the higher fraction of classical Be stars, as well as the presence of Oe stars, in the lower metallicity Magellanic Clouds. We conclude with a

  17. Cervical intervertebral disc replacement.

    Science.gov (United States)

    Cason, Garrick W; Herkowitz, Harry N

    2013-02-06

    Symptomatic adjacent-level disease after cervical fusion has led to the development and testing of several disc-replacement prostheses. Randomized controlled trials of cervical disc replacement (CDR) compared with anterior cervical discectomy and fusion (ACDF) have demonstrated at least equivalent clinical results for CDR with similar or lower complication rates. Biomechanical, kinematic, and radiographic studies of CDR reveal that the surgical level and adjacent vertebral level motion and center of rotation more closely mimic the native state. Lower intradiscal pressures adjacent to CDR may help decrease the incidence of adjacent spinal-level disease, but long-term follow-up is necessary to evaluate this theory.

  18. Isolated Optic Disc Tuberculosis

    Science.gov (United States)

    Mansour, Ahmad M.; Tabbara, Khalid F.; Tabbarah, Zuhair

    2015-01-01

    We present a healthy male subject who developed progressive visual loss in the left eye initially diagnosed as optic neuritis. Upon suspicion of infectious etiology, testing was positive for tuberculosis. There were no signs or symptoms of active systemic tuberculosis infection. The patient responded swiftly to antimycobacterial therapy with return of vision and resolution of disc swelling. Positive purified protein derivative skin test, negative chest radiograph, negative systemic workup, negative workup for other causes of unilateral optic neuritis and quick response to mycobacterial therapy reaffirm the entity of isolated optic disc tuberculosis similar to isolated choroidal tuberculosis without systemic manifestation. PMID:26483675

  19. Isolated Optic Disc Tuberculosis

    Directory of Open Access Journals (Sweden)

    Ahmad M. Mansour

    2015-09-01

    Full Text Available We present a healthy male subject who developed progressive visual loss in the left eye initially diagnosed as optic neuritis. Upon suspicion of infectious etiology, testing was positive for tuberculosis. There were no signs or symptoms of active systemic tuberculosis infection. The patient responded swiftly to antimycobacterial therapy with return of vision and resolution of disc swelling. Positive purified protein derivative skin test, negative chest radiograph, negative systemic workup, negative workup for other causes of unilateral optic neuritis and quick response to mycobacterial therapy reaffirm the entity of isolated optic disc tuberculosis similar to isolated choroidal tuberculosis without systemic manifestation.

  20. Gd-enhanced MR imaging of the herniated lumbar disc: patterns of enhancement

    Energy Technology Data Exchange (ETDEWEB)

    Kwag, Hyon Joo; Choi, Hye Young; Kim, Hyae Young; Kim, Yoo Kyung; Kim, Ah Young; Chung, Eun Chul [College of Medicine, Ewah Womans University, Seoul (Korea, Republic of)

    1995-07-15

    The purpose of this study is to describe the patterns of enhancement of the herniated lumbar disc with Gd-DTPA enhanced MR imaging. Out of 65 patients, 103 lumbar discs diagnosed to be herniated by MR image were retrospectively analyzed. The MR imaging was performed with 1.5 T MR unit, using T1-and T2-weighted sagittal and axial spin echo techniques. Contrast-enhanced T1 weighted sagittal and axial images were performed after intravenous injection of Gadopentetate-dimeglumine(Magnevist, Shering) (0.1 mmol/kg). Contrast enhancement was seen in 66 cases(64%). Thirteen cases of bulging disc were not enhanced. Twenty-eight cases of protruded disc showed intraannular enchantment in 23 cases, peripheral linear and irregular enhancement in each of one case, and nonenhancement in three cases. Fifty-seven cases of extruded disc showed irregular enhancement in 14 cases, peripheral linear enhancement in 12 cases, peripheral ring enhancement in five cases and intraannular enhancement in five cases. All five cases of sequestered disc showed peripheral ring enhancement. Protruded discs show intraannular enhancement frequently and sequestered discs usually show peripheral ring enhancement. Enhanced MR imaging may be helpful to evaluate the type of herniated lumbar disc and relationship among disc material, nerve root and thecal sac.

  1. Gd-enhanced MR imaging of the herniated lumbar disc: patterns of enhancement

    International Nuclear Information System (INIS)

    Kwag, Hyon Joo; Choi, Hye Young; Kim, Hyae Young; Kim, Yoo Kyung; Kim, Ah Young; Chung, Eun Chul

    1995-01-01

    The purpose of this study is to describe the patterns of enhancement of the herniated lumbar disc with Gd-DTPA enhanced MR imaging. Out of 65 patients, 103 lumbar discs diagnosed to be herniated by MR image were retrospectively analyzed. The MR imaging was performed with 1.5 T MR unit, using T1-and T2-weighted sagittal and axial spin echo techniques. Contrast-enhanced T1 weighted sagittal and axial images were performed after intravenous injection of Gadopentetate-dimeglumine(Magnevist, Shering) (0.1 mmol/kg). Contrast enhancement was seen in 66 cases(64%). Thirteen cases of bulging disc were not enhanced. Twenty-eight cases of protruded disc showed intraannular enchantment in 23 cases, peripheral linear and irregular enhancement in each of one case, and nonenhancement in three cases. Fifty-seven cases of extruded disc showed irregular enhancement in 14 cases, peripheral linear enhancement in 12 cases, peripheral ring enhancement in five cases and intraannular enhancement in five cases. All five cases of sequestered disc showed peripheral ring enhancement. Protruded discs show intraannular enhancement frequently and sequestered discs usually show peripheral ring enhancement. Enhanced MR imaging may be helpful to evaluate the type of herniated lumbar disc and relationship among disc material, nerve root and thecal sac

  2. Tracing Planets in Circumstellar Discs

    Directory of Open Access Journals (Sweden)

    Uribe Ana L.

    2013-04-01

    Full Text Available Planets are assumed to form in circumstellar discs around young stellar objects. The additional gravitational potential of a planet perturbs the disc and leads to characteristic structures, i.e. spiral waves and gaps, in the disc density profile. We perform a large-scale parameter study on the observability of these planet-induced structures in circumstellar discs in the (submm wavelength range for the Atacama Large (SubMillimeter Array (ALMA. On the basis of hydrodynamical and magneto-hydrodynamical simulations of star-disc-planet models we calculate the disc temperature structure and (submm images of these systems. These are used to derive simulated ALMA maps. Because appropriate objects are frequent in the Taurus-Auriga region, we focus on a distance of 140 pc and a declination of ≈ 20°. The explored range of star-disc-planet configurations consists of six hydrodynamical simulations (including magnetic fields and different planet masses, nine disc sizes with outer radii ranging from 9 AU to 225 AU, 15 total disc masses in the range between 2.67·10-7 M⊙ and 4.10·10-2 M⊙, six different central stars and two different grain size distributions, resulting in 10 000 disc models. At almost all scales and in particular down to a scale of a few AU, ALMA is able to trace disc structures induced by planet-disc interaction or the influence of magnetic fields in the wavelength range between 0.4...2.0 mm. In most cases, the optimum angular resolution is limited by the sensitivity of ALMA. However, within the range of typical masses of protoplane tary discs (0.1 M⊙...0.001 M⊙ the disc mass has a minor impact on the observability. At the distance of 140 pc it is possible to resolve discs down to 2.67·10-6 M⊙ and trace gaps in discs with 2.67·10-4 M⊙ with a signal-to-noise ratio greater than three. In general, it is more likely to trace planet-induced gaps in magneto-hydrodynamical disc models, because gaps are wider in the presence of

  3. The DISC Quotient

    Science.gov (United States)

    Elliott, John R.; Baxter, Stephen

    2012-09-01

    D.I.S.C: Decipherment Impact of a Signal's Content. The authors present a numerical method to characterise the significance of the receipt of a complex and potentially decipherable signal from extraterrestrial intelligence (ETI). The purpose of the scale is to facilitate the public communication of work on any such claimed signal, as such work proceeds, and to assist in its discussion and interpretation. Building on a "position" paper rationale, this paper looks at the DISC quotient proposed and develops the algorithmic steps and comprising measures that form this post detection strategy for information dissemination, based on prior work on message detection, decipherment. As argued, we require a robust and incremental strategy, to disseminate timely, accurate and meaningful information, to the scientific community and the general public, in the event we receive an "alien" signal that displays decipherable information. This post-detection strategy is to serve as a stepwise algorithm for a logical approach to information extraction and a vehicle for sequential information dissemination, to manage societal impact. The "DISC Quotient", which is based on signal analysis processing stages, includes factors based on the signal's data quantity, structure, affinity to known human languages, and likely decipherment times. Comparisons with human and other phenomena are included as a guide to assessing likely societal impact. It is submitted that the development, refinement and implementation of DISC as an integral strategy, during the complex processes involved in post detection and decipherment, is essential if we wish to minimize disruption and optimize dissemination.

  4. Optic disc drusen

    DEFF Research Database (Denmark)

    Fledelius, Hans C

    2017-01-01

    , which, in view of the small disc at risk, may seem a paradox. METHODS: This is an observational retrospective study on an eye clinic series (n = 49), focusing on visual acuity, kinetic/static perimetry, and longitudinal trends, to include the question of eventual visual incapacity. RESULTS: Forty...

  5. Spin current

    CERN Document Server

    Valenzuela, Sergio O; Saitoh, Eiji; Kimura, Takashi

    2017-01-01

    Since the discovery of the giant magnetoresistance effect in magnetic multilayers in 1988, a new branch of physics and technology, called spin-electronics or spintronics, has emerged, where the flow of electrical charge as well as the flow of electron spin, the so-called “spin current,” are manipulated and controlled together. The physics of magnetism and the application of spin current have progressed in tandem with the nanofabrication technology of magnets and the engineering of interfaces and thin films. This book aims to provide an introduction and guide to the new physics and applications of spin current, with an emphasis on the interaction between spin and charge currents in magnetic nanostructures.

  6. Spin Electronics

    Science.gov (United States)

    2003-08-01

    applications, a ferromagnetic metal may be used as a source of spin-polarized electronics to be injected into a semiconductor, a superconductor or a...physical phenomena in II-VI and III-V semiconductors. In II-VI systems, the Mn2+ ions act to boost the electron spin precession up to terahertz ...conductors, proximity effect between ferromagnets and superconductors , and the effects of spin injection on the physical properties of the

  7. Spin doctoring

    OpenAIRE

    Vozková, Markéta

    2011-01-01

    1 ABSTRACT The aim of this text is to provide an analysis of the phenomenon of spin doctoring in the Euro-Atlantic area. Spin doctors are educated people in the fields of semiotics, cultural studies, public relations, political communication and especially familiar with the infrastructure and the functioning of the media industry. Critical reflection of manipulative communication techniques puts spin phenomenon in historical perspective and traces its practical use in today's social communica...

  8. LUMBAR DISC HERNIATION

    Science.gov (United States)

    Vialle, Luis Roberto; Vialle, Emiliano Neves; Suárez Henao, Juan Esteban; Giraldo, Gustavo

    2015-01-01

    Lumbar disc herniation is the most common diagnosis among the degenerative abnormalities of the lumbar spine (affecting 2 to 3% of the population), and is the principal cause of spinal surgery among the adult population. The typical clinical picture includes initial lumbalgia, followed by progressive sciatica. The natural history of disc herniation is one of rapid resolution of the symptoms (four to six weeks). The initial treatment should be conservative, managed through medication and physiotherapy, sometimes associated with percutaneous nerve root block. Surgical treatment is indicated if pain control is unsuccessful, if there is a motor deficit greater than grade 3, if there is radicular pain associated with foraminal stenosis, or if cauda equina syndrome is present. The latter represents a medical emergency. A refined surgical technique, with removal of the extruded fragment and preservation of the ligamentum flavum, resolves the sciatic symptoms and reduces the risk of recurrence over the long term. PMID:27019834

  9. Wave disc engine apparatus

    Energy Technology Data Exchange (ETDEWEB)

    Muller, Norbert; Piechna, Janusz; Sun, Guangwei; Parraga, Pablo-Francisco

    2018-01-02

    A wave disc engine apparatus is provided. A further aspect employs a constricted nozzle in a wave rotor channel. A further aspect provides a sharp bend between an inlet and an outlet in a fluid pathway of a wave rotor, with the bend being spaced away from a peripheral edge of the wave rotor. A radial wave rotor for generating electricity in an automotive vehicle is disclosed in yet another aspect.

  10. Cervical Total Disc Arthroplasty

    OpenAIRE

    Basho, Rahul; Hood, Kenneth A.

    2012-01-01

    Symptomatic adjacent segment degeneration of the cervical spine remains problematic for patients and surgeons alike. Despite advances in surgical techniques and instrumentation, the solution remains elusive. Spurred by the success of total joint arthroplasty in hips and knees, surgeons and industry have turned to motion preservation devices in the cervical spine. By preserving motion at the diseased level, the hope is that adjacent segment degeneration can be prevented. Multiple cervical disc...

  11. Energy thrift and improved performance achieved through novel railway brake discs

    International Nuclear Information System (INIS)

    Tirovic, Marko

    2009-01-01

    A disc with radial vanes and circumferential pillars proves to be successful in operation and achieves energy efficiency improvements compared with those of traditional design. Cooling characteristics of this novel design are practically identical to the disc with tangential vanes but the equivalent aerodynamic (air pumping) losses are approximately 50% less. It is shown that these reductions in pumping losses can lead to substantial energy savings in train operations. When developing new designs and/or comparing different railway disc designs, the proposed disc cooling to aerodynamic efficiency ratio (η v ) was found to be a very useful parameter to assess. This 'efficiency ratio' - a ratio of convective power dissipation to aerodynamic power losses can help in achieving adequate balance of cooling efficiency and aerodynamic losses to suit particular application. The use of CFD is of enormous benefit in generating discs that fulfil these demanding requirements, with the spin rig being exceptionally useful for experimental work

  12. Polarimetric microlensing of circumstellar discs

    Science.gov (United States)

    Sajadian, Sedighe; Rahvar, Sohrab

    2015-12-01

    We study the benefits of polarimetry observations of microlensing events to detect and characterize circumstellar discs around the microlensed stars located at the Galactic bulge. These discs which are unresolvable from their host stars make a net polarization effect due to their projected elliptical shapes. Gravitational microlensing can magnify these signals and make them be resolved. The main aim of this work is to determine what extra information about these discs can be extracted from polarimetry observations of microlensing events in addition to those given by photometry ones. Hot discs which are closer to their host stars are more likely to be detected by microlensing, owing to more contributions in the total flux. By considering this kind of discs, we show that although the polarimetric efficiency for detecting discs is similar to the photometric observation, but polarimetry observations can help to constraint the disc geometrical parameters e.g. the disc inner radius and the lens trajectory with respect to the disc semimajor axis. On the other hand, the time-scale of polarimetric curves of these microlensing events generally increases while their photometric time-scale does not change. By performing a Monte Carlo simulation, we show that almost four optically thin discs around the Galactic bulge sources are detected (or even characterized) through photometry (or polarimetry) observations of high-magnification microlensing events during 10-yr monitoring of 150 million objects.

  13. Total disc replacement.

    Science.gov (United States)

    Vital, J-M; Boissière, L

    2014-02-01

    Total disc replacement (TDR) (partial disc replacement will not be described) has been used in the lumbar spine since the 1980s, and more recently in the cervical spine. Although the biomechanical concepts are the same and both are inserted through an anterior approach, lumbar TDR is conventionally indicated for chronic low back pain, whereas cervical TDR is used for soft discal hernia resulting in cervicobrachial neuralgia. The insertion technique must be rigorous, with precise centering in the disc space, taking account of vascular anatomy, which is more complex in the lumbar region, particularly proximally to L5-S1. All of the numerous studies, including prospective randomized comparative trials, have demonstrated non-inferiority to fusion, or even short-term superiority regarding speed of improvement. The main implant-related complication is bridging heterotopic ossification with resulting loss of range of motion and increased rates of adjacent segment degeneration, although with an incidence lower than after arthrodesis. A sufficiently long follow-up, which has not yet been reached, will be necessary to establish definitively an advantage for TDR, particularly in the cervical spine. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

  14. Bladed disc crack diagnostics using blade passage signals

    Science.gov (United States)

    Hanachi, Houman; Liu, Jie; Banerjee, Avisekh; Koul, Ashok; Liang, Ming; Alavi, Elham

    2012-12-01

    One of the major potential faults in a turbo fan engine is the crack initiation and propagation in bladed discs under cyclic loads that could result in the breakdown of the engines if not detected at an early stage. Reliable fault detection techniques are therefore in demand to reduce maintenance cost and prevent catastrophic failures. Although a number of approaches have been reported in the literature, it remains very challenging to develop a reliable technique to accurately estimate the health condition of a rotating bladed disc. Correspondingly, this paper presents a novel technique for bladed disc crack detection through two sequential signal processing stages: (1) signal preprocessing that aims to eliminate the noises in the blade passage signals; (2) signal postprocessing that intends to identify the crack location. In the first stage, physics-based modeling and interpretation are established to help characterize the noises. The crack initiation can be determined based on the calculated health monitoring index derived from the sinusoidal effects. In the second stage, the crack is located through advanced detrended fluctuation analysis of the preprocessed data. The proposed technique is validated using a set of spin rig test data (i.e. tip clearance and time of arrival) that was acquired during a test conducted on a bladed military engine fan disc. The test results have demonstrated that the developed technique is an effective approach for identifying and locating the incipient crack that occurs at the root of a bladed disc.

  15. Spin glasses

    CERN Document Server

    Bovier, Anton

    2007-01-01

    Spin glass theory is going through a stunning period of progress while finding exciting new applications in areas beyond theoretical physics, in particular in combinatorics and computer science. This collection of state-of-the-art review papers written by leading experts in the field covers the topic from a wide variety of angles. The topics covered are mean field spin glasses, including a pedagogical account of Talagrand's proof of the Parisi solution, short range spin glasses, emphasizing the open problem of the relevance of the mean-field theory for lattice models, and the dynamics of spin glasses, in particular the problem of ageing in mean field models. The book will serve as a concise introduction to the state of the art of spin glass theory, usefull to both graduate students and young researchers, as well as to anyone curious to know what is going on in this exciting area of mathematical physics.

  16. Dermal exposure assessment of pesticide use: The case of sprayers in potato farms in the Colombian highlands

    Energy Technology Data Exchange (ETDEWEB)

    Lesmes-Fabian, Camilo, E-mail: camilo.lesmes@geographie.uni-muenchen.de [Department of Geography, University of Munich, Luisenstrasse 37, D-80333 Munich (Germany); Institute for Systems Science, Innovation and Sustainability Research, Karl-Franzens University of Graz, Merangase 18/I, A-8010 Graz (Austria); Garcia-Santos, Glenda [Department of Geography, University of Zurich, Winterthurerstrasse 190, 8057 Zurich (Switzerland); Leuenberger, Fanny [Institute of Geology, Swiss Federal Institute of Technology (ETH), Sonneggstrasse 5, 8092 Zurich (Switzerland); Nuyttens, David [Institute for Agricultural and Fisheries Research, Technology and Food Science Unit, Agricultural Engineering, Burg. van Gansberghelaan 115 bus 1, 9820 Merelbeke (Belgium); Binder, Claudia R. [Department of Geography, University of Munich, Luisenstrasse 37, D-80333 Munich (Germany); Institute for Systems Science, Innovation and Sustainability Research, Karl-Franzens University of Graz, Merangase 18/I, A-8010 Graz (Austria)

    2012-07-15

    Quantifying dermal exposure to pesticides in farming systems in developing countries is of special interest for the estimation of potential health risks, especially when there is a lack of occupational hygiene regulations. In this paper we present the results of a dermal exposure assessment for the potato farming system in the highlands of Colombia, where farmers apply pesticides with hand pressure sprayers without any personal protective equipment. The fractioning of the pesticide, in terms of potential and actual dermal exposure, was determined via the whole-body dosimetry methodology, using the tracer uranine as pesticide surrogate, and luminescence spectrometry as analytical method. We assessed the three activities involved in pesticide management: preparation, application, and cleaning; analyzed three types of nozzles: one with a standard discharge and two modified by farmers to increase the discharge; and derived the protection factor given by work clothing. Our results suggest that to reduce the health risk, three aspects have to be considered: (i) avoiding the modification of nozzles, which affects the droplet size spectrum and increases the level of dermal exposure; (ii) using adequate work clothing made of thick fabrics, especially on the upper body parts; and (iii) cleaning properly the tank sprayer before the application activity. - Highlights: Black-Right-Pointing-Pointer We assessed dermal exposure to pesticides in the potato farming system in Colombia. Black-Right-Pointing-Pointer High potential exposure was found in lower body parts during the application. Black-Right-Pointing-Pointer High actual exposure was found in arms and back due to inadequate protection. Black-Right-Pointing-Pointer There is a high health risk of using Metamidophos under current working conditions.

  17. Dermal exposure assessment of pesticide use: The case of sprayers in potato farms in the Colombian highlands

    International Nuclear Information System (INIS)

    Lesmes-Fabian, Camilo; García-Santos, Glenda; Leuenberger, Fanny; Nuyttens, David; Binder, Claudia R.

    2012-01-01

    Quantifying dermal exposure to pesticides in farming systems in developing countries is of special interest for the estimation of potential health risks, especially when there is a lack of occupational hygiene regulations. In this paper we present the results of a dermal exposure assessment for the potato farming system in the highlands of Colombia, where farmers apply pesticides with hand pressure sprayers without any personal protective equipment. The fractioning of the pesticide, in terms of potential and actual dermal exposure, was determined via the whole-body dosimetry methodology, using the tracer uranine as pesticide surrogate, and luminescence spectrometry as analytical method. We assessed the three activities involved in pesticide management: preparation, application, and cleaning; analyzed three types of nozzles: one with a standard discharge and two modified by farmers to increase the discharge; and derived the protection factor given by work clothing. Our results suggest that to reduce the health risk, three aspects have to be considered: (i) avoiding the modification of nozzles, which affects the droplet size spectrum and increases the level of dermal exposure; (ii) using adequate work clothing made of thick fabrics, especially on the upper body parts; and (iii) cleaning properly the tank sprayer before the application activity. - Highlights: ► We assessed dermal exposure to pesticides in the potato farming system in Colombia. ► High potential exposure was found in lower body parts during the application. ► High actual exposure was found in arms and back due to inadequate protection. ► There is a high health risk of using Metamidophos under current working conditions.

  18. [Temporomandibular joint disc surgery].

    Science.gov (United States)

    Potier, J; Maes, J-M; Nicot, R; Dumousseau, T; Cotelle, M; Ferri, J

    2016-09-01

    Temporomandibular joint (TMJ) disorders are a common disease and may be responsible for major functional and painful repercussions. Treatment is not consensual. The literature highlights the role of conservative treatments (physiotherapy, analgesics, splints) in a first attempt. Minimally invasive surgical techniques (arthroscopy, arthrocentesis) have developed rapidly in recent decades. They have proven effective and reliable, especially in patients suffering from irreducible or reducible anterior disc dislocation or presenting with arthopathies. The goal of our work was to make an update about disk surgery. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

  19. Herniated lumbar disc: injection interventions for sciatica

    OpenAIRE

    Jordan, Joanne L; Konstantinou, Kika; O'Dowd, John

    2016-01-01

    Herniated lumbar disc is a displacement of disc material (nucleus pulposus or annulus fibrosus) beyond the intervertebral disc space. The highest prevalence is among people aged 30 to 50 years, with a male to female ratio of 2:1.

  20. TOPICAL REVIEW: Spin current, spin accumulation and spin Hall effect

    Directory of Open Access Journals (Sweden)

    Saburo Takahashi and Sadamichi Maekawa

    2008-01-01

    Full Text Available Nonlocal spin transport in nanostructured devices with ferromagnetic injector (F1 and detector (F2 electrodes connected to a normal conductor (N is studied. We reveal how the spin transport depends on interface resistance, electrode resistance, spin polarization and spin diffusion length, and obtain the conditions for efficient spin injection, spin accumulation and spin current in the device. It is demonstrated that the spin Hall effect is caused by spin–orbit scattering in nonmagnetic conductors and gives rise to the conversion between spin and charge currents in a nonlocal device. A method of evaluating spin–orbit coupling in nonmagnetic metals is proposed.

  1. Gravitating discs around black holes

    International Nuclear Information System (INIS)

    Karas, V; Hure, J-M; Semerak, O

    2004-01-01

    Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole-disc system using analytical solutions of stationary, axially symmetric Einstein equations. Then, more detailed considerations are focused to the middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate. Within general relativity, only a static case has been analysed in detail. Results are often very inspiring. However, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging are completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the surrounding environment. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star-disc interactions, which can be recognized in observational properties, such as the relation between the central mass and stellar velocity dispersion. (topical review)

  2. Radicular interdural lumbar disc herniation

    Science.gov (United States)

    Boulahroud, Omar; Elasri, Abad; Elmostarchid, Brahim; Boucetta, Mohammed

    2009-01-01

    Intraradicular lumbar disc herniation is a rare complication of disc disease that is generally diagnosed only during surgery. The mechanism for herniated disc penetration into the intradural space is not known with certainty, but adhesion between the radicular dura and the posterior longitudinal ligament was suggested as the most important condition. The authors report the first case of an intraradicular lumbar disc herniation without subdural penetration; the disc hernia was lodged between the two radicular dura layers. The patient, a 34-year-old soldier, was admitted with a 12-month history of low back pain and episodic left sciatica. Neurologic examination showed a positive straight leg raising test on the left side without sensory, motor or sphincter disturbances. Spinal CT scan and MRI exploration revealed a left posterolateral osteophyte formation at the L5–S1 level with an irregular large disc herniation, which migrated superiorly. An intradural extension was suspected. A left L5 hemilaminectomy and S1 foraminotomy were performed. The exploration revealed a large fragment of disc material located between the inner and outer layers of the left S1 radicular dura. The mass was extirpated without cerebrospinal fluid outflow. The postoperative course was uneventful. Radicular interdural lumbar disc herniation should be suspected when a swollen, hard and immobile nerve root is present intraoperatively. PMID:19888608

  3. Spin electronics

    CERN Document Server

    Buhrman, Robert; Daughton, James; Molnár, Stephan; Roukes, Michael

    2004-01-01

    This report is a comparative review of spin electronics ("spintronics") research and development activities in the United States, Japan, and Western Europe conducted by a panel of leading U.S. experts in the field. It covers materials, fabrication and characterization of magnetic nanostructures, magnetism and spin control in magnetic nanostructures, magneto-optical properties of semiconductors, and magnetoelectronics and devices. The panel's conclusions are based on a literature review and a series of site visits to leading spin electronics research centers in Japan and Western Europe. The panel found that Japan is clearly the world leader in new material synthesis and characterization; it is also a leader in magneto-optical properties of semiconductor devices. Europe is strong in theory pertaining to spin electronics, including injection device structures such as tunneling devices, and band structure predictions of materials properties, and in development of magnetic semiconductors and semiconductor heterost...

  4. Spin glasses

    International Nuclear Information System (INIS)

    Fischer, K.H.; Hertz, J.A.

    1993-01-01

    Spin glasses, simply defined by the authors as a collection of spins (i.e., magnetic moments) whose low-temperature state is a frozen disordered one, represent one of the fascinating new fields of study in condensed matter physics, and this book is the first to offer a comprehensive account of the subject. Included are discussions of the most important developments in theory, experimental work, and computer modeling of spin glasses, all of which have taken place essentially within the last two decades. The first part of the book gives a general introduction to the basic concepts and a discussion of mean field theory, while the second half concentrates on experimental results, scaling theory, and computer simulation of the structure of spin glasses

  5. Changes in orientation and shape of protoplanetary discs moving through an ambient medium

    NARCIS (Netherlands)

    T.P.G. Wijnen (Thomas); F.I. Pelupessy (Inti); O.R. Pols (Onno); S. Portegies Zwart (Simon)

    2017-01-01

    textabstractMisalignments between the orbital planes of planets and the equatorial planes of their host stars have been observed in our solar system, in transiting exoplanets, and for the orbital planes of debris discs. We present a mechanism that causes such a spin-orbit misalignment for a

  6. Gd-DTPA-enhanced MR in thoracic disc herniations

    Energy Technology Data Exchange (ETDEWEB)

    Parizel, P.M.; Rodesch, G.; Baleriaux, D.; Segebarth, C.; Zegers de Beyl, D.; Haens, J. d' ; Noterman, J.

    1989-03-01

    The Gd-DTPA-enhanced magnetic resonance findings in two patients with herniated thoracic intervertebral discs are reported. The first patient was a 56-year-old woman with a small subligamentous T6-7 disc herniation, slightly lateralized to the right. The second patient was a 51-year-old man with a central and right posterolateral disc herniation, including a large calcified fragment, at the T8-9 level. The nonenhanced MR examination revealed the presence of an extradural mass lesion in both patients, impinging upon the dural sac and compressing and displacing the spinal cord posteriorly. The lesion was slightly hypointense on both T1- and T2-weighted spin echo sequences. Following intravenous injection of Gd-DTPA in a dosage of 0.1 mmol/kg body weight, enhancement of the posterior longitudinal ligament was noted and triangular areas of contrast uptake were seen to occur in the epidural space above and below the herniated disc. At surgery, they were found to correspond to dilated and congested epidural veins.

  7. Increased levels of oxidative DNA damage in pesticide sprayers in Thessaly Region (Greece). Implications of pesticide exposure.

    Science.gov (United States)

    Koureas, Michalis; Tsezou, Aspasia; Tsakalof, Andreas; Orfanidou, Timoklia; Hadjichristodoulou, Christos

    2014-10-15

    The widespread use of pesticides substances nowadays largely guarantees the protection of crops and people from undesired pests. However, exposure to pesticides was related to a variety of human health effects. The present study was conducted in the region of Thessaly which is characterized by intensive agricultural activities and wide use of pesticides. The study aimed at estimating the oxidative damage to DNA in different subpopulations in Thessaly region (Greece) and investigating its correlation with exposure to pesticides and other potential risk factors. In total, the study involved 80 pesticide sprayers, 85 rural residents and 121 individuals, inhabitants of the city of Larissa. Demographic characteristics, habits, medical history and exposure history of the participants to pesticides were recorded by personal interviews. Blood and urine samples were collected from all participants. For the measurement of exposure to organophosphorus insecticides, dialkylphosphate (DAP) metabolites were quantified in urine, by gas chromatography-mass spectrometry. Genomic DNA was extracted from peripheral blood samples and the oxidation by-product 8-hydroxydeoxyguanosine (8-OHdG) was determined by Enzyme Immuno-Assay. Urinary metabolite concentrations were not associated with 8-OHdG levels but it was found that pesticide sprayers had significantly higher levels of 8-OHdG (p=0.007) in comparison to the control group. Last season's exposure to insecticides and fungicides, expressed as total area treated multiplied by the number of applications, showed a statistically significant association with the risk of having high 8-OHdG levels [RR: 2.19 (95%CI:1.09-4.38) and RR: 2.32 (95% CI:1.16-4.64) respectively]. Additionally, from the subgroups of pesticides examined, seasonal exposure to neonicotinoid insecticides [RR: 2.22 (95% CI:1.07-4.63)] and glufosinate ammonium [RR: 3.26 (95% CI:1.38-7.69)] was found to have the greater impact on 8-OHdG levels. This study produced findings

  8. Are galaxy discs optically thick?

    International Nuclear Information System (INIS)

    Disney, Michael; Davies, Jonathan; Phillipps, Steven

    1989-01-01

    We re-examine the classical optical evidence for the low optical depths traditionally assigned to spiral discs and argue that it is highly model-dependent and unconvincing. In particular, layered models with a physically thin but optically thick dust layer behave like optically thin discs. The opposite hypotheses, that such discs are optically thick is then examined in the light of modern evidence. We find it to be consistent with the near-infrared and IRAS observations, with the surface brightnesses, with the HI and CO column densities and with the Hα measurements. (author)

  9. High-performance spinning device for DVD-based micromechanical signal transduction

    DEFF Research Database (Denmark)

    Hwu, En-Te; Chen, Ching-Hsiu; Bosco, Filippo

    2013-01-01

    Here we report a high-throughput spinning device for nanometric scale measurements of microstructures with instrumentation details and experimental results. The readout technology implemented in the designed disc-like device is based on a DVD data storage optical pick-up unit (OPU). With a spinning...

  10. On total disc replacement.

    Science.gov (United States)

    Berg, Svante

    2011-02-01

    Low back pain consumes a large part of the community's resources dedicated to health care and sick leave. Back disorders also negatively affect the individual leading to pain suffering, decreased quality-of-life and disability. Chronic low back pain (CLBP) due to degenerative disc disease (DDD) is today often treated with fusion when conservative treatment has failed and symptoms are severe. This treatment is as successful as arthroplasty is for hip arthritis in restoring the patient's quality of life and reducing disability. Even so, there are some problems with this treatment, one of these being recurrent CLBP from an adjacent segment (ASD) after primarily successful surgery. This has led to the development of alternative surgical treatments and devices that maintain or restore mobility, in order to reduce the risk for ASD. Of these new devices, the most frequently used are the disc prostheses used in Total Disc Replacement (TDR). This thesis is based on four studies comparing total disc replacement with posterior fusion. The studies are all based on a material of 152 patients with DDD in one or two segments, aged 20-55 years that were randomly treated with either posterior fusion or TDR. The first study concerned clinical outcome and complications. Follow-up was 100% at both one and two years. It revealed that both treatment groups had a clear benefit from treatment and that patients with TDR were better in almost all outcome scores at one-year follow-up. Fusion patients continued to improve during the second year. At two-year follow-up there was a remaining difference in favour of TDR for back pain. 73% in the TDR group and 63% in the fusion group were much better or totally pain-free (n.s.), while twice as many patients in the TDR group were totally pain free (30%) compared to the fusion group (15%). Time of surgery and total time in hospital were shorter in the TDR group. There was no difference in complications and reoperations, except that seventeen of the

  11. Optical, Nanomechanical and Electrochemical Sensing on a DVD Disc

    DEFF Research Database (Denmark)

    Boisen, Anja

    2014-01-01

    Our vision is to create a platform where optical, nanomecanical and electrochemical sensors can be integrated and read-out using the mechanics and the optics from DVDs and Blu-Rays. Integrating sensors on a disc allows us to use centrifugal microfluidis which has been developed for more than 50...... years and which has proven to be a simple and powerful way to manipulate liquid samples without the need of external pumps [1]. As an example, serum can be separated from a whole blood sample in a few minutes by simply spinning the disc and allowing the cellular components to sediment. Cantilever...... time as having the benefit of the centrifugal liquid handling. As an example it is simple to measure in flow conditions and to perform continuous cyclic voltammograms in different concentrations of electrolytes using built-in valves. In conclusion, the merger of sensors and centrifugal microfluidcs...

  12. A simple framework for modelling the dependence of bulk Comptonization by turbulence on accretion disc parameters

    Science.gov (United States)

    Kaufman, J.; Blaes, O. M.; Hirose, S.

    2018-03-01

    Warm Comptonization models for the soft X-ray excess in AGN do not self-consistently explain the relationship between the Comptonizing medium and the underlying accretion disc. Because of this, they cannot directly connect the fitted Comptonization temperatures and optical depths to accretion disc parameters. Since bulk velocities exceed thermal velocities in highly radiation pressure dominated discs, in these systems bulk Comptonization by turbulence may provide a physical basis in the disc itself for warm Comptonization models. We model the dependence of bulk Comptonization on fundamental accretion disc parameters, such as mass, luminosity, radius, spin, inner boundary condition, and α. In addition to constraining warm Comptonization models, our model can help distinguish contributions from bulk Comptonization to the soft X-ray excess from those due to other physical mechanisms, such as absorption and reflection. By linking the time variability of bulk Comptonization to fluctuations in the disc vertical structure due to MRI turbulence, our results show that observations of the soft X-ray excess can be used to study disc turbulence in the radiation pressure dominated regime. Because our model connects bulk Comptonization to one dimensional vertical structure temperature profiles in a physically intuitive way, it will be useful for understanding this effect in future simulations run in new regimes.

  13. Comparison of Animal Discs Used in Disc Research to Human Lumbar Disc: Torsion Mechanics and Collagen Content

    Science.gov (United States)

    Showalter, Brent L.; Beckstein, Jesse C.; Martin, John T.; Beattie, Elizabeth E.; Orías, Alejandro A. Espinoza; Schaer, Thomas P.; Vresilovic, Edward J.; Elliott, Dawn M.

    2012-01-01

    Study Design Experimental measurement and normalization of in vitro disc torsion mechanics and collagen content for several animal species used in intervertebral disc research and comparing these to the human disc. Objective To aid in the selection of appropriate animal models for disc research by measuring torsional mechanical properties and collagen content. Summary of Background Data There is lack of data and variability in testing protocols for comparing animal and human disc torsion mechanics and collagen content. Methods Intervertebral disc torsion mechanics were measured and normalized by disc height and polar moment of inertia for 11 disc types in 8 mammalian species: the calf, pig, baboon, goat, sheep, rabbit, rat, and mouse lumbar, and cow, rat, and mouse caudal. Collagen content was measured and normalized by dry weight for the same discs except the rat and mouse. Collagen fiber stretch in torsion was calculated using an analytical model. Results Measured torsion parameters varied by several orders of magnitude across the different species. After geometric normalization, only the sheep and pig discs were statistically different from human. Fiber stretch was found to be highly dependent on the assumed initial fiber angle. The collagen content of the discs was similar, especially in the outer annulus where only the calf and goat discs were statistically different from human. Disc collagen content did not correlate with torsion mechanics. Conclusion Disc torsion mechanics are comparable to human lumbar discs in 9 of 11 disc types after normalization by geometry. The normalized torsion mechanics and collagen content of the multiple animal discs presented is useful for selecting and interpreting results for animal models of the disc. Structural composition of the disc, such as initial fiber angle, may explain the differences that were noted between species after geometric normalization. PMID:22333953

  14. Development and evaluation of a combined cultivator and band sprayer with a row-centering RTK-GPS guidance system.

    Science.gov (United States)

    Perez-Ruiz, Manuel; Carballido, Jacob; Agüera, Juan; Rodríguez-Lizana, Antonio

    2013-03-11

    Typically, low-pressure sprayers are used to uniformly apply pre- and post-emergent herbicides to control weeds in crop rows. An innovative machine for weed control in inter-row and intra-row areas, with a unique combination of inter-row cultivation tooling and intra-row band spraying for six rows and an electro-hydraulic side-shift frame controlled by a GPS system, was developed and evaluated. Two weed management strategies were tested in the field trials: broadcast spraying (the conventional method) and band spraying with mechanical weed control using RTK-GPS (the experimental method). This approach enabled the comparison between treatments from the perspective of cost savings and efficacy in weed control for a sugar beet crop. During the 2010-2011 season, the herbicide application rate (112 L ha(-1)) of the experimental method was approximately 50% of the conventional method, and thus a significant reduction in the operating costs of weed management was achieved. A comparison of the 0.2-trimmed means of weed population post-treatment showed that the treatments achieved similar weed control rates at each weed survey date. Sugar beet yields were similar with both methods (p = 0.92). The use of the experimental equipment is cost-effective on ≥20 ha of crops. These initial results show good potential for reducing herbicide application in the Spanish beet industry.

  15. Development and Evaluation of a Combined Cultivator and Band Sprayer with a Row-Centering RTK-GPS Guidance System

    Directory of Open Access Journals (Sweden)

    Antonio Rodríguez-Lizana

    2013-03-01

    Full Text Available Typically, low-pressure sprayers are used to uniformly apply pre- and post-emergent herbicides to control weeds in crop rows. An innovative machine for weed control in inter-row and intra-row areas, with a unique combination of inter-row cultivation tooling and intra-row band spraying for six rows and an electro-hydraulic side-shift frame controlled by a GPS system, was developed and evaluated. Two weed management strategies were tested in the field trials: broadcast spraying (the conventional method and band spraying with mechanical weed control using RTK-GPS (the experimental method. This approach enabled the comparison between treatments from the perspective of cost savings and efficacy in weed control for a sugar beet crop. During the 2010–2011 season, the herbicide application rate (112 L ha−1 of the experimental method was approximately 50% of the conventional method, and thus a significant reduction in the operating costs of weed management was achieved. A comparison of the 0.2-trimmed means of weed population post-treatment showed that the treatments achieved similar weed control rates at each weed survey date. Sugar beet yields were similar with both methods (p = 0.92. The use of the experimental equipment is cost-effective on ≥20 ha of crops. These initial results show good potential for reducing herbicide application in the Spanish beet industry.

  16. Potential Dermal Exposure in greenhouses for manual sprayers: Analysis of the mix/load, application and re-entry stages

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Laura M.; Querejeta, Giselle A.; Flores, Andrea P.; Hughes, Enrique A.; Zalts, Anita [Instituto de Ciencias, Universidad Nacional de General Sarmiento (UNGS), J. M. Gutierrez 1150, (B1613GSX) Los Polvorines, Prov. de Buenos Aires (Argentina); Montserrat, Javier M., E-mail: jmontser@ungs.edu.ar [Instituto de Ciencias, Universidad Nacional de General Sarmiento (UNGS), J. M. Gutierrez 1150, (B1613GSX) Los Polvorines, Prov. de Buenos Aires (Argentina); Instituto de Investigaciones en Ingenieria Genetica y Biologia Molecular (CONICET), Vuelta de Obligado 2490, 2o piso, Buenos Aires (Argentina)

    2010-09-01

    An evaluation of the Potential Dermal Exposure for the mix/load, application and re-entry stages, associated with procymidone and deltamethrin usage, was carried out for tomatoes grown in greenhouses of small production units in Argentina. Eight experiments were done with four different operators, under typical field conditions with a lever operated backpack sprayer. The methodology applied was based on the Whole Body Dosimetry technique, evaluating a set of different data for the mix and load, application and re-entry operations. These results indicated that the Potential Dermal Exposure of the application step was (38 {+-} 17) mL h{sup -1} with the highest proportion on torso, head and arms. When the three stages were compared, re-entry was found to contribute least towards the total Potential Dermal Exposure; meanwhile in all cases, except one, the mix/load operation was the stage with highest exposure. The Margin of Safety for each different operation was also calculated and the proportion of pesticide drift from the greenhouse to the environment is presented. These results emphasize the importance of improving the personal protection measures in the mix and load stage, an operation that is not usually associated with high-risk in small production units.

  17. Hematological Abnormality, Oxidative Stress, and Genotoxicity Induction in the Greenhouse Pesticide Sprayers; Investigating the Role of NQO1 Gene Polymorphism

    Directory of Open Access Journals (Sweden)

    Nahid Ahmadi

    2018-02-01

    Full Text Available The widespread use of pesticides in agriculture represents a threat to the human populations exposed to them. In this cross-sectional study, the hematological and biochemical parameters, plasma cholinesterase (PChE activity, oxidative stress, genotoxicity, and NAD(PH: quinone oxidoreductase 1 (NQO1 C609T polymorphism were measured in 100 greenhouse workers occupationally exposed to pesticide mixture and 104 normal healthy controls. There was a decrease in erythrocytes (5.45%, p = 0.026 and hemoglobin (3.26%, p = 0.025, and an increase in mean corpuscular hemoglobin (3.54%, p = 0.013 in the exposed workers. Sprayers showed a reduction in PChE (23% and GSH (50% levels, and an increase in lipid peroxidation (LPO (55%, protein carbonyl (145%, Superoxide dismutase activity (61%, and total antioxidant capacity (35% (p < 0.001 for all parameters but LPO: p = 0.009. Genotoxicity parameters were significantly high in the exposed cases (for all parameters: p < 0.001 but tail length: p = 0.002. There was a significant correlation between oxidative stress and genotoxicity parameters, and also between these biomarkers and PChE activity. The NQO1 C609T polymorphism was not significantly associated with studied biomarkers. The findings indicate that occupational exposure to a mixture of pesticides can induce hematotoxicity, oxidative stress, and genotoxicity in greenhouse workers.

  18. A Skyrme model approach to the spin-orbit force

    Energy Technology Data Exchange (ETDEWEB)

    Halcrow, C.J.; Manton, N.S. [Department of Applied Mathematics and Theoretical Physics,University of Cambridge, Wilberforce Road, Cambridge CB3 0WA (United Kingdom)

    2015-01-07

    The spin-orbit force is a vital tool in describing finite nuclei and nucleon interactions; however its microscopic origin is not fully understood. In this paper we study a model inspired by Skyrmions which provides a classical explanation of the force. To simplify the calculations the Skyrmions are approximated as two-dimensional rigid discs which behave like quantum cogwheels.

  19. Transverse vibration of spinning disk with attached distributed patch ...

    African Journals Online (AJOL)

    Free and forced transverse vibration characteristics of a thin spinning disc attached to a rigid core have been investigated by finite element analysis using ANSYS software. The effect of discrete point masses and patches of distributed masses attached at the periphery of the plate on free and forced vibration behavior of a ...

  20. Lumbar disc excision through fenestration

    Directory of Open Access Journals (Sweden)

    Sangwan S

    2006-01-01

    Full Text Available Background : Lumbar disc herniation often causes sciatica. Many different techniques have been advocated with the aim of least possible damage to other structures while dealing with prolapsed disc surgically in the properly selected and indicated cases. Methods : Twenty six patients with clinical symptoms and signs of prolapsed lumbar intervertebral disc having radiological correlation by MRI study were subjected to disc excision by interlaminar fenestration method. Results : The assessment at follow-up showed excellent results in 17 patients, good in 6 patients, fair in 2 patients and poor in 1 patient. The mean preoperative and postoperative Visual Analogue Scores were 9.34 ±0.84 and 2.19 ±0.84 on scale of 0-10 respectively. These were statistically significant (p value< 0.001, paired t test. No significant complications were recorded. Conclusion : Procedures of interlaminar fenestration and open disc excision under direct vision offers sufficient adequate exposure for lumbar disc excision with a smaller incision, lesser morbidity, shorter convalescence, early return to work and comparable overall results in the centers where recent laser and endoscopy facilities are not available.

  1. Interference Spins

    DEFF Research Database (Denmark)

    Popovski, Petar; Simeone, Osvaldo; Nielsen, Jimmy Jessen

    2015-01-01

    on traffic load and interference condition leads to performance gains. In this letter, a general network of multiple interfering two-way links is studied under the assumption of a balanced load in the two directions for each link. Using the notion of interference spin, we introduce an algebraic framework...

  2. Spinning worlds

    NARCIS (Netherlands)

    Schwarz, H.

    2017-01-01

    The thesis "Spinning Worlds" is about the characterisation of two types of gas-giant exoplanets: Hot Jupiters, with orbital periods of fewer than five days, and young, wide-orbit gas giants, with orbital periods as long as thousands of years. The thesis is based on near-infrared observations of 1

  3. Disc piezoelectric ceramic transformers.

    Science.gov (United States)

    Erhart, Jirií; Půlpán, Petr; Doleček, Roman; Psota, Pavel; Lédl, Vít

    2013-08-01

    In this contribution, we present our study on disc-shaped and homogeneously poled piezoelectric ceramic transformers working in planar-extensional vibration modes. Transformers are designed with electrodes divided into wedge, axisymmetrical ring-dot, moonie, smile, or yin-yang segments. Transformation ratio, efficiency, and input and output impedances were measured for low-power signals. Transformer efficiency and transformation ratio were measured as a function of frequency and impedance load in the secondary circuit. Optimum impedance for the maximum efficiency has been found. Maximum efficiency and no-load transformation ratio can reach almost 100% and 52 for the fundamental resonance of ring-dot transformers and 98% and 67 for the second resonance of 2-segment wedge transformers. Maximum efficiency was reached at optimum impedance, which is in the range from 500 Ω to 10 kΩ, depending on the electrode pattern and size. Fundamental vibration mode and its overtones were further studied using frequency-modulated digital holographic interferometry and by the finite element method. Complementary information has been obtained by the infrared camera visualization of surface temperature profiles at higher driving power.

  4. In a spin at Brookhaven spin physics

    CERN Document Server

    Makdisi, Y I

    2003-01-01

    The mysterious quantity that is spin took centre stage at Brookhaven for the SPIN2002 meeting last September. The 15th biennial International Spin Physics Symposium (SPIN2002) was held at Brookhaven National Laboratory on 9-14 September 2002. Some 250 spin enthusiasts attended, including experimenters and theorists in both nuclear and high-energy physics, as well as accelerator physicists and polarized target and polarized source experts. The six-day symposium included 23 plenary talks and 150 parallel talks. SPIN2002 was preceded by a one-day spin physics tutorial for students, postdocs, and anyone else who felt the need for a refresher course. (2 refs).

  5. Spinning Flight Dynamics of Frisbees, Boomerangs, Samaras, and Skipping Stones

    CERN Document Server

    Lorenz, Ralph D

    2006-01-01

    More frisbees are sold each year than baseballs, basketballs, and footballs combined. Yet these familiar flying objects have subtle and clever aerodynamic and gyrodynamic properties which are only recently being documented by wind tunnel and other studies. In common with other rotating bodies discussed in this readily accessible book, they are typically not treated in textbooks of aeronautics and the literature is scattered in a variety of places. This book develops the theme of disc-wings and spinning aerospace vehicles in parallel. Many readers will have enjoyed these vehicles and their dynamics in recreational settings, so this book will be of wide interest. In addition to spinning objects of various shapes, several exotic manned aircraft with disc platforms have been proposed and prototypes built - these include a Nazi ‘secret weapon’ and the De Havilland Avrocar, also discussed in the book. Boomerangs represent another category of spinning aerodynamic body whose behavior can only be understood by cou...

  6. Spin-Circuit Representation of Spin Pumping

    Science.gov (United States)

    Roy, Kuntal

    2017-07-01

    Circuit theory has been tremendously successful in translating physical equations into circuit elements in an organized form for further analysis and proposing creative designs for applications. With the advent of new materials and phenomena in the field of spintronics and nanomagnetics, it is imperative to construct the spin-circuit representations for different materials and phenomena. Spin pumping is a phenomenon by which a pure spin current can be injected into the adjacent layers. If the adjacent layer is a material with a high spin-orbit coupling, a considerable amount of charge voltage can be generated via the inverse spin Hall effect allowing spin detection. Here we develop the spin-circuit representation of spin pumping. We then combine it with the spin-circuit representation for the materials having spin Hall effect to show that it reproduces the standard results as in the literature. We further show how complex multilayers can be analyzed by simply writing a netlist.

  7. Spin Coherence in Semiconductor Nanostructures

    National Research Council Canada - National Science Library

    Flatte, Michael E

    2006-01-01

    ... dots, tuning of spin coherence times for electron spin, tuning of dipolar magnetic fields for nuclear spin, spontaneous spin polarization generation and new designs for spin-based teleportation and spin transistors...

  8. CFD simulation of pesticide spray from air-assisted sprayers in an apple orchard: Tree deposition and off-target losses

    Science.gov (United States)

    Hong, Se-Woon; Zhao, Lingying; Zhu, Heping

    2018-02-01

    The ultimate goal of a pesticide spraying system is to provide adequate coverage on intended canopies with a minimum amount of spray materials and off-target waste. Better spray coverage requires an understanding of the fate and transport of spray droplets carried by turbulent airflows in orchards. In this study, an integrated computational fluid dynamics (CFD) model was developed to predict displacement of pesticide spray droplets discharged from an air-assisted sprayer, depositions onto tree canopies, and off-target deposition and airborne drift in an apple orchard. Pesticide droplets discharged from a moving sprayer were tracked using the Lagrangian particle transport model, and the deposition model was applied to droplets entering porous canopy zones. Measurements of the droplet deposition and drift in the same orchard were used to validate the model simulations. Good agreement was found between the measured and simulated spray concentrations inside tree canopies and off-target losses (ground deposition and airborne drifts) with the overall relative errors of 22.1% and 40.6%, respectively, under three growth stages. The CFD model was able to estimate the mass balance of pesticide droplets in the orchard, which was practically difficult to investigate by measurements in field conditions. As the foliage of trees became denser, spray deposition inside canopies increased from 8.5% to 65.8% and airborne drift and ground deposition decreased from 25.8% to 7.0% and 47.8% to 21.2%, respectively. Higher wind speed also increased the spray airborne drift downwind of the orchard. This study demonstrates that CFD model can be used to evaluate spray application performance and design and operate sprayers with increased spray efficiencies and reduced drift potentials.

  9. Construção e uso do pulverizador-logarítmico manual Construction and use of the manual logarithmic sprayer

    Directory of Open Access Journals (Sweden)

    F. S. de Almeida

    1982-12-01

    Full Text Available Descreve-se a construção do pulverizador-logarítmico, seu funcionamento e gama de aplicações. Deduzem-se as fórmulas matemáticas em que o mesmo se baseia. Apresentam-se ábacos que permitem determinar a concentração de calda em qualquer ponto da área pulverizada.The construction of a logaritmic-sprayer, its functioning, and range of applications are described. The mathematic formulas in which it is based are inferred. The abacus that allows the solution concentration determination in any point of the treated area is presented.

  10. Vertebral osteomyelitis without disc involvement

    Energy Technology Data Exchange (ETDEWEB)

    Kamani, I.; Syed, I.; Saifuddin, A. E-mail: asaifuddin@aol.com; Green, R.; MacSweeney, F

    2004-10-01

    Vertebral osteomyelitis is most commonly due to pyogenic or granulomatous infection and typically results in the combined involvement of the intervertebral disc and adjacent vertebral bodies. Non-infective causes include the related conditions of chronic recurrent multifocal osteomyelitis (CRMO) and SAPHO (synovitis, acne, pustulosis, hyperostosis, and osteitis) syndrome. Occasionally, these conditions may present purely within the vertebral body, resulting in various combinations of vertebral marrow oedema and sclerosis, destructive lesions of the vertebral body and pathological vertebral collapse, thus mimicking neoplastic disease. This review illustrates the imaging features of vertebral osteomyelitis without disc involvement, with emphasis on magnetic resonance imaging (MRI) findings.

  11. Intervertebral disc degeneration : Studies in the loaded disc culture system

    NARCIS (Netherlands)

    Paul, C.P.L.

    2018-01-01

    In dit proefschrift wordt een model beschreven, het Loaded Disc Culture System (LDCS), voor het ex vivo bestuderen van de effecten van mechanische belasting op de tussenwervelschijf. In hoofdstuk 2 laten we zien dat een zekere dosis aan dagelijkse belasting nodig is om de cellen van de

  12. Dead discs, unstable discs and the stars they surround

    Directory of Open Access Journals (Sweden)

    D’Angelo Caroline

    2014-01-01

    Full Text Available Strong stellar magnetic fields significantly alter the behaviour of surrounding accretion discs. Recent work has demonstrated that at low accretion rates a large amount of mass can remain confined in the disc, contrary to the standard assumption that the magnetic field will expel the disc in an outflow (the “propeller regime”. These “dead discs” often become unstable, causing cycles of accretion onto the central star. Here I present the main predictions of this model, and argue that it provides a good explanation for the peculiar behaviour seen in several accreting sources with strong magnetic fields. I will focus in particular on three accreting millisecond X-ray pulsars: SAX J1808.4-3658, NGC 6440 X-2 and IGR J00291+5934. These sources all show low-frequency quasi-periodic oscillations consistent with a variable accretion rate, as well as unusual outburst patterns that suggest gas is confined in the inner disc regions during quiescence.

  13. Generation of inclined protoplanetary discs and misaligned planets through mass accretion - I. Coplanar secondary discs

    Science.gov (United States)

    Xiang-Gruess, M.; Kroupa, P.

    2017-10-01

    We study the three-dimensional (3D) evolution of a viscous protoplanetary disc that accretes gas material from a second protoplanetary disc during a close encounter in an embedded star cluster. The aim is to investigate the capability of the mass accretion scenario to generate strongly inclined gaseous discs that could later form misaligned planets. We use smoothed particle hydrodynamics to study mass transfer and disc inclination for passing stars and circumstellar discs with different masses. We explore different orbital configurations to find the parameter space that allows significant disc inclination generation. Thies et al. suggested that significant disc inclination and disc or planetary system shrinkage can generally be produced by the accretion of external gas material with a different angular momentum. We found that this condition can be fulfilled for a large range of gas mass and angular momentum. For all encounters, mass accretion from the secondary disc increases with decreasing mass of the secondary proto-star. Thus, higher disc inclinations can be attained for lower secondary stellar masses. Variations of the secondary disc's orientation relative to the orbital plane can alter the disc evolution significantly. The results taken together show that mass accretion can change the 3D disc orientation significantly resulting in strongly inclined discs. In combination with the gravitational interaction between the two star-disc systems, this scenario is relevant for explaining the formation of highly inclined discs that could later form misaligned planets.

  14. Galactic nuclei evolution with spinning black holes: method and implementation

    Science.gov (United States)

    Fiacconi, Davide; Sijacki, Debora; Pringle, J. E.

    2018-04-01

    Supermassive black holes at the centre of galactic nuclei mostly grow in mass through gas accretion over cosmic time. This process also modifies the angular momentum (or spin) of black holes, both in magnitude and in orientation. Despite being often neglected in galaxy formation simulations, spin plays a crucial role in modulating accretion power, driving jet feedback, and determining recoil velocity of coalescing black hole binaries. We present a new accretion model for the moving-mesh code AREPO that incorporates (i) mass accretion through a thin α-disc, and (ii) spin evolution through the Bardeen-Petterson effect. We use a diverse suite of idealised simulations to explore the physical connection between spin evolution and larger scale environment. We find that black holes with mass ≲ 107 M⊙ experience quick alignment with the accretion disc. This favours prolonged phases of spin-up, and the spin direction evolves according to the gas inflow on timescales as short as ≲ 100 Myr, which might explain the observed jet direction distribution in Seyfert galaxies. Heavier black holes (≳ 108 M⊙) are instead more sensitive to the local gas kinematic. Here we find a wider distribution in spin magnitudes: spin-ups are favoured if gas inflow maintains a preferential direction, and spin-downs occur for nearly isotropic infall, while the spin direction does not change much over short timescales ˜100 Myr. We therefore conclude that supermassive black holes with masses ≳ 5 × 108 M⊙ may be the ideal testbed to determine the main mode of black hole fuelling over cosmic time.

  15. Spontaneous regression of an intraspinal disc cyst

    Energy Technology Data Exchange (ETDEWEB)

    Demaerel, P.; Eerens, I.; Wilms, G. [University Hospital, Leuven (Belgium). Dept. of Radiology; Goffin, J. [Dept. of Neurosurgery, University Hospitals, Leuven (Belgium)

    2001-11-01

    We present a patient with a so-called disc cyst. Its location in the ventrolateral epidural space and its communication with the herniated disc are clearly shown. The disc cyst developed rapidly and regressed spontaneously. This observation, which has not been reported until now, appears to support focal degeneration with cyst formation as the pathogenesis. (orig.)

  16. Thermochemical modelling of brown dwarf discs

    NARCIS (Netherlands)

    Greenwood, A. J.; Kamp, I.; Waters, L. B. F. M.; Woitke, P.; Thi, W.-F.; Rab, Ch.; Aresu, G.; Spaans, M.

    The physical properties of brown dwarf discs, in terms of their shapes and sizes, are still largely unexplored by observations. ALMA has by far the best capabilities to observe these discs in sub-mm CO lines and dust continuum, while also spatially resolving some discs. To what extent brown dwarf

  17. 46 CFR 64.61 - Rupture disc.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 2 2010-10-01 2010-10-01 false Rupture disc. 64.61 Section 64.61 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) MARINE ENGINEERING MARINE PORTABLE TANKS AND CARGO HANDLING SYSTEMS Pressure Relief Devices and Vacuum Relief Devices for MPTs § 64.61 Rupture disc. If a rupture disc...

  18. Novel therapeutic strategies for degenerative disc disease: Review of cell biology and intervertebral disc cell therapy.

    Science.gov (United States)

    Fernandez-Moure, Joseph; Moore, Caitlyn A; Kim, Keemberly; Karim, Azim; Smith, Kevin; Barbosa, Zonia; Van Eps, Jeffrey; Rameshwar, Pranela; Weiner, Bradley

    2018-01-01

    Intervertebral disc degeneration is a disease of the discs connecting adjoining vertebrae in which structural damage leads to loss of disc integrity. Degeneration of the disc can be a normal process of ageing, but can also be precipitated by other factors. Literature has made substantial progress in understanding the biological basis of intervertebral disc, which is reviewed here. Current medical and surgical management strategies have shortcomings that do not lend promise to be effective solutions in the coming years. With advances in understanding the cell biology and characteristics of the intervertebral disc at the molecular and cellular level that have been made, alternative strategies for addressing disc pathology can be discovered. A brief overview of the anatomic, cellular, and molecular structure of the intervertebral disc is provided as well as cellular and molecular pathophysiology surrounding intervertebral disc degeneration. Potential therapeutic strategies involving stem cell, protein, and genetic therapy for intervertebral disc degeneration are further discussed.

  19. Massive disc formation in the tidal disruption of a neutron star by a nearly extremal black hole

    International Nuclear Information System (INIS)

    Lovelace, Geoffrey; Kidder, Lawrence E; Duez, Matthew D; Foucart, Francois; Pfeiffer, Harald P; Scheel, Mark A; Szilágyi, Béla

    2013-01-01

    Black hole–neutron star (BHNS) binaries are important sources of gravitational waves for second-generation interferometers, and BHNS mergers are also a proposed engine for short, hard gamma-ray bursts. The behavior of both the spacetime (and thus the emitted gravitational waves) and the neutron-star matter in a BHNS merger depend strongly and nonlinearly on the black hole's spin. While there is a significant possibility that astrophysical black holes could have spins that are nearly extremal (i.e. near the theoretical maximum), to date fully relativistic simulations of BHNS binaries have included black-hole spins only up to S/M 2 = 0.9, which corresponds to the black hole having approximately half as much rotational energy as possible, given the black hole's mass. In this paper, we present a new simulation of a BHNS binary with a mass ratio q = 3 and black-hole spin S/M 2 = 0.97, the highest simulated to date. We find that the black hole's large spin leads to the most massive accretion disc and the largest tidal tail outflow of any fully relativistic BHNS simulations to date, even exceeding the results implied by extrapolating results from simulations with lower black-hole spin. The disc appears to be remarkably stable. We also find that the high black-hole spin persists until shortly before the time of merger; afterward, both merger and accretion spin down the black hole. (paper)

  20. Electromagnetic Levitation of a Disc

    Science.gov (United States)

    Valle, R.; Neves, F.; de Andrade, R., Jr.; Stephan, R. M.

    2012-01-01

    This paper presents a teaching experiment that explores the levitation of a disc of ferromagnetic material in the presence of the magnetic field produced by a single electromagnet. In comparison to the classical experiment of the levitation of a sphere, the main advantage of the proposed laboratory bench is that the uniform magnetic field…

  1. Intervertebral disc degeneration in dogs

    NARCIS (Netherlands)

    Bergknut, Niklas

    Back pain is common in both dogs and humans, and is often associated with intervertebral disc (IVD) degeneration. The IVDs are essential structures of the spine and degeneration can ultimately result in diseases such as IVD herniation or spinal instability. In order to design new treatments halting

  2. Intervertebral disc degeneration in dogs

    NARCIS (Netherlands)

    Bergknut, N.|info:eu-repo/dai/nl/314418059

    2011-01-01

    Back pain is common in both dogs and humans, and is often associated with intervertebral disc (IVD) degeneration. The IVDs are essential structures of the spine and degeneration can ultimately result in diseases such as IVD herniation or spinal instability. In order to design new treatments halting

  3. Episodic cauda equina compression from an intradural lumbar herniated disc: a case of 'floppy disc'.

    Science.gov (United States)

    Nagaria, J; Chan, Cc; Kamel, Mh; McEvoy, L; Bolger, C

    2011-09-01

    Intradural disc herniation (IDDH) is a rare complication of intervertebral disc disease and comprises 0.26-0.30% of all herniated discs, with 92% of them located in the lumbar region (1). We present a case of IDDH that presented with intermittent symptoms and signs of cauda equina compression. We were unable to find in the literature, any previously described cases of intermittent cauda equina compression from a herniated intradural disc fragment leading to a "floppy disc syndrome". © JSCR.

  4. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level

    OpenAIRE

    Hakan, Tayfun; G?rcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain ...

  5. Heat and spin interconversion

    International Nuclear Information System (INIS)

    Ohnuma, Yuichi; Matsuo, Mamoru; Maekawa, Sadamichi; Saitoh, Eeiji

    2017-01-01

    Spin Seebeck and spin Peltier effects, which are mutual conversion phenomena of heat and spin, are discussed on the basis of the microscopic theory. First, the spin Seebeck effect, which is the spin-current generation due to heat current, is discussed. The recent progress in research on the spin Seebeck effect are introduced. We explain the origin of the observed sign changes of the spin Seebeck effect in compensated ferromagnets. Next, the spin Peltier effect, which is the heat-current generation due to spin current, is discussed. Finally, we show that the spin Seebeck and spin Peltier effects are summarized by Onsager's reciprocal relation and derive Kelvin's relation for the spin and heat transports. (author)

  6. MR imaging findings of a sequestered disc in the lumbar spine: a comparison with an extruded disc

    Energy Technology Data Exchange (ETDEWEB)

    Sim, Su Youn; Park, Ji Seon; Ryu, Kyung Nam [Kyung Hee University Medical Center, Seoul (Korea, Republic of); Jin, Wook [Kyung Hee University East-west Neo Medical Center, Seoul (Korea, Republic of)

    2007-10-15

    To compare the MR findings of a sequestered disc with an extruded disc. MR images of 28 patients with a sequestered disc and 18 patients with an extruded disc were retrospectively reviewed. Patients with sequestered discs were divided into two groups whether definite separation from the parent disc was or was not seen. In the latter group (definite separation not seen) and the extruded disc group of patients, the signal intensities of the herniated discs were compared with the signal intensities of the parent discs and were evaluated on T1-and T2-weighted images. We also assessed the presence of a notch within the herniated disc. In the sequestered disc group of patients (28 discs), only 5 discs (18%) showed obvious separation from the parent disc. Among the remaining 23 discs with indefinite separation, the notch was visible in 14 discs (61%) and 9 discs (39%) had no notch. In the extruded disc group (18 discs), the notch was visible in 2 (11%) discs and the difference between the two groups was statistically significant ({rho} 0.0002). The signal intensities of the herniated discs on T1-weighted images were isointense in both the sequestered and extruded discs. The difference of incidence of high signal intensities on T2-weighted images was not statistically significant ({rho} = 0.125). It is necessary to consider the possibility of the presence of a sequestered disc when a herniated disc material shows a notch.

  7. MR imaging findings of a sequestered disc in the lumbar spine: a comparison with an extruded disc

    International Nuclear Information System (INIS)

    Sim, Su Youn; Park, Ji Seon; Ryu, Kyung Nam; Jin, Wook

    2007-01-01

    To compare the MR findings of a sequestered disc with an extruded disc. MR images of 28 patients with a sequestered disc and 18 patients with an extruded disc were retrospectively reviewed. Patients with sequestered discs were divided into two groups whether definite separation from the parent disc was or was not seen. In the latter group (definite separation not seen) and the extruded disc group of patients, the signal intensities of the herniated discs were compared with the signal intensities of the parent discs and were evaluated on T1-and T2-weighted images. We also assessed the presence of a notch within the herniated disc. In the sequestered disc group of patients (28 discs), only 5 discs (18%) showed obvious separation from the parent disc. Among the remaining 23 discs with indefinite separation, the notch was visible in 14 discs (61%) and 9 discs (39%) had no notch. In the extruded disc group (18 discs), the notch was visible in 2 (11%) discs and the difference between the two groups was statistically significant (ρ 0.0002). The signal intensities of the herniated discs on T1-weighted images were isointense in both the sequestered and extruded discs. The difference of incidence of high signal intensities on T2-weighted images was not statistically significant (ρ = 0.125). It is necessary to consider the possibility of the presence of a sequestered disc when a herniated disc material shows a notch

  8. The effects of the forward speed and air volume of an air-assisted sprayer on spray deposition in tendone trained vineyards

    Directory of Open Access Journals (Sweden)

    Simone Pascuzzi

    2013-12-01

    Full Text Available This paper reports the results of spray application trials in a tendone trained vineyard in order to evaluate the influence of forward speed and air volume on the foliar deposition of plant protection products (PPPs, maintaining roughly constant the volume applied. The trials used an air-assisted sprayer with a centrifugal fan and 4+4 adjustable fan-shaped diffusers, each with a nozzle-holder group. A full factorial experimental design was implemented, with three forward speeds and two airflow rates, organised with a randomised complete block design including three replicates. In order to consider the influence of canopy development, the tests (one spray application for each replicate of a mixture containing a water-soluble food dye as a tracer were replicated during two phenological stages: i the end of flowering; and ii berry touch. Leaves were picked at random from the canopy after each spray treatment, and foliar PPP deposition was evaluated using a spectrophotometer. This analysis of foliar deposition showed that the airflow rates produced by the fan were unsuitable for the dense canopy typical of this type of vineyard. However, the special shape of the diffusers may make this sprayer effective if the main objective of pesticide applications in tendone trained table grape vineyards is to control bunch diseases.

  9. Intervertebral disc calcifications in children.

    Science.gov (United States)

    Beluffi, G; Fiori, P; Sileo, C

    2009-03-01

    This study was done to assess the presence of both asymptomatic and symptomatic intervertebral disc calcifications in a large paediatric population. We retrospectively reviewed the radiographs taken during the past 26 years in children (age 0-18 years) undergoing imaging of the spine or of other body segments in which the spine was adequately depicted, to determine possible intervertebral disc calcifications. The following clinical evaluation was extrapolated from the patients' charts: presence of spinal symptoms, history of trauma, suspected or clinically evident scoliosis, suspected or clinically evident syndromes, bone dysplasias, and pre- or postoperative chest or abdominal X-rays. We detected intervertebral disc calcifications in six patients only. Five calcifications were asymptomatic (one newborn baby with Patau syndrome; three patients studied to rule out scoliosis, hypochondroplasia and syndromic traits; one for dyspnoea due to sunflower seeds inhalation). Only one was symptomatic, with acute neck pain. Calcifications varied in number from one in one patient to two to five in the others. Apart from the calcification in the patient with cervical pain, all calcifications were asymptomatic and constituted an incidental finding (particularly those detected at the thoracic level in the patient studied for sunflower-seed inhalation). Calcification shapes were either linear or round. Our series confirms that intervertebral disc calcifications are a rare finding in childhood and should not be a source of concern: symptomatic calcifications tend to regress spontaneously within a short time with or without therapy and immobilisation, whereas asymptomatic calcifications may last for years but disappear before the age of 20 years. Only very few cases, such as those of medullary compression or severe dysphagia due to anterior herniation of cervical discs, may require surgical procedures.

  10. Disc degeneration: current surgical options

    Directory of Open Access Journals (Sweden)

    C Schizas

    2010-10-01

    Full Text Available Chronic low back pain attributed to lumbar disc degeneration poses a serious challenge to physicians. Surgery may be indicated in selected cases following failure of appropriate conservative treatment. For decades, the only surgical option has been spinal fusion, but its results have been inconsistent. Some prospective trials show superiority over usual conservative measures while others fail to demonstrate its advantages. In an effort to improve results of fusion and to decrease the incidence of adjacent segment degeneration, total disc replacement techniques have been introduced and studied extensively. Short-term results have shown superiority over some fusion techniques. Mid-term results however tend to show that this approach yields results equivalent to those of spinal fusion. Nucleus replacement has gained some popularity initially, but evidence on its efficacy is scarce. Dynamic stabilisation, a technique involving less rigid implants than in spinal fusion and performed without the need for bone grafting, represents another surgical option. Evidence again is lacking on its superiority over other surgical strategies and conservative measures. Insertion of interspinous devices posteriorly, aiming at redistributing loads and relieving pain, has been used as an adjunct to disc removal surgery for disc herniation. To date however, there is no clear evidence on their efficacy. Minimally invasive intradiscal thermocoagulation techniques have also been tried, but evidence of their effectiveness is questioned. Surgery using novel biological solutions may be the future of discogenic pain treatment. Collaboration between clinicians and basic scientists in this multidisciplinary field will undoubtedly shape the future of treating symptomatic disc degeneration.

  11. CT findings of lumbar intervertebral disc: II. Disc herniation (HNP)

    International Nuclear Information System (INIS)

    Yang, W. J.; Lee, J. M.; Bahk, Y. W.

    1984-01-01

    In lumbar region the epidural fat pad is relatively abundant so that CT can provides sufficient information in diagnosis of lumbar HNP. Many authors have reported on the CT findings of HNP such as focal nodular protrusion of the posterior disc margin, obliteration of epidural fat pad, impingement of dural sac and nerve root, swelling of nerve root, soft tissue density in the spinal canal and calcification of disc. However there was so previous report describing incidence and reliability of the findings. It is the purpose of the present study to survey the frequency, reliability, and limitation of these CT findings. The clinical material was consisted of 30 operatively proven cases of HNP of the lumbar spine. Each lumbar CT scan was reviewed retrospectively and the findings were analysed by two radiologists independently. There were 20 males and 10 females and the mean age was 36.7 years. Involvement of L4-S5 level was 2.3 times more frequent than that of L5-S1 level. Of 30 cases, 22 were unilateral posterolateral types and 8 cases central or unilateral far lateral types. CT findings observed were nodular protrusion of the posterior margin of the disc, obliteration of epidural fat pad, impingement of dural sac or nerve root, soft tissue density in the spinal canal and calcification in the posterior portion of the protruded disc, in order of decreasing frequency. The conclusions are follows: 1. Nodular protrusion of the posterior disc margin accompanied by obliteration of epidural fat pad was observed in every case. The former findings was designated as direct sign and the latter indirect. 2. Obliteration of the epidural fat appears to be significant in lateral recesses especially when it occurs unilaterally. This was not true, however, in the centrally located fat pad. 3. Impingement of the dural sac and nerve root were observed in 90% and 67%, respectively, and were very helpful in establishing HNP diagnosis when the direct and indirect signs were equivocal

  12. Factors that influence recurrent lumbar disc herniation.

    Science.gov (United States)

    Yaman, M E; Kazancı, A; Yaman, N D; Baş, F; Ayberk, G

    2017-06-01

    The most common cause of poor outcome following lumbar disc surgery is recurrent herniation. Recurrence has been noted in 5% to 15% of patients with surgically treated primary lumbar disc herniation. There have been many studies designed to determine the risk factors for recurrent lumbar disc herniation. In this study, we retrospectively analysed the influence of disc degeneration, endplate changes, surgical technique, and patient's clinical characteristics on recurrent lumbar disc herniation. Patients who underwent primary single-level L4-L5 lumbar discectomy and who were reoperated on for recurrent L4-L5 disc herniation were retrospectively reviewed. All these operations were performed between August 2004 and September 2009 at the Neurosurgery Department of Ataturk Education and Research Hospital in Ankara, Turkey. During the study period, 126 patients were reviewed, with 101 patients underwent primary single-level L4-L5 lumbar discectomy and 25 patients were reoperated on for recurrent L4-L5 disc herniation. Preoperative higher intervertebral disc height (Pdisc herniation had preoperative higher disc height and higher body mass index. Modic endplate changes had a higher tendency for recurrence of lumbar disc herniation. Well-planned and well-conducted large-scale prospective cohort studies are needed to confirm this and enable convenient treatment modalities to prevent recurrent disc pathology.

  13. Three-level cervical disc herniation

    Directory of Open Access Journals (Sweden)

    St. Iencean Andrei

    2015-09-01

    Full Text Available Multilevel cervical degenerative disc disease is well known in the cervical spine pathology, with radicular syndromes or cervical myelopathy. One or two level cervical herniated disc is common in adult and multilevel cervical degenerative disc herniation is common in the elderly, with spinal stenosis, and have the same cause: the gradual degeneration of the disc. We report the case of a patient with two level cervical disc herniation (C4 – C5 and C5 – C6 treated by anterior cervical microdiscectomy both levels and fusion at C5 – C6; after five years the patient returned with left C7 radiculopathy and MRI provided the image of a left C6 – C7 disc herniation, he underwent an anterior microsurgical discectomy with rapid relief of symptoms. Three-level cervical herniated disc are rare in adults, and the anterior microdiscectomy with or without fusion solve this pathology.

  14. Migrated herniated disc mimicking a neoplasm.

    Science.gov (United States)

    Hoch, Benjamin; Hermann, George

    2010-12-01

    Disc sequestration is defined as migration of a herniated disc fragment into the epidural space such that it is completely separated from the parent disc. We report a case of a migrated herniated disc that was initially pathologically diagnosed as a cartilage neoplasm. In addition to confounding morphological features, this interpretation may have been influenced by an initial radiological interpretation that did not include herniated disc in the differential diagnosis of a spinal lesion with prominent peripheral contrast enhancement. MR imaging is most helpful in considering other lesions in the differential diagnosis including abscess, hematoma, and primary or metastatic neoplasms. Pathologically, degenerative changes in herniated discs, including clustering of chondrocytes and neovascularization, may be severe resulting in a pseudoneoplastic appearance. Increased awareness of the radiological and pathological features of migrated herniated disc should limit confusion with other tumors.

  15. Retina image–based optic disc segmentation

    Directory of Open Access Journals (Sweden)

    Ching-Lin Wang

    2016-05-01

    Full Text Available The change of optic disc can be used to diagnose many eye diseases, such as glaucoma, diabetic retinopathy and macular degeneration. Moreover, retinal blood vessel pattern is unique for human beings even for identical twins. It is a highly stable pattern in biometric identification. Since optic disc is the beginning of the optic nerve and main blood vessels in retina, it can be used as a reference point of identification. Therefore, optic disc segmentation is an important technique for developing a human identity recognition system and eye disease diagnostic system. This article hence presents an optic disc segmentation method to extract the optic disc from a retina image. The experimental results show that the optic disc segmentation method can give impressive results in segmenting the optic disc from a retina image.

  16. Nuclear spin pumping and electron spin susceptibilities

    NARCIS (Netherlands)

    Danon, J.; Nazarov, Y.V.

    2011-01-01

    In this work we present a new formalism to evaluate the nuclear spin dynamics driven by hyperfine interaction with nonequilibrium electron spins. To describe the dynamics up to second order in the hyperfine coupling it suffices to evaluate the susceptibility and fluctuations of the electron spin.

  17. Magnetic Nanostructures Spin Dynamics and Spin Transport

    CERN Document Server

    Farle, Michael

    2013-01-01

    Nanomagnetism and spintronics is a rapidly expanding and increasingly important field of research with many applications already on the market and many more to be expected in the near future. This field started in the mid-1980s with the discovery of the GMR effect, recently awarded with the Nobel prize to Albert Fert and Peter Grünberg. The present volume covers the most important and most timely aspects of magnetic heterostructures, including spin torque effects, spin injection, spin transport, spin fluctuations, proximity effects, and electrical control of spin valves. The chapters are written by internationally recognized experts in their respective fields and provide an overview of the latest status.

  18. Gravitating discs around black holes

    Czech Academy of Sciences Publication Activity Database

    Karas, Vladimír; Huré, J.-M.; Semerák, O.

    2004-01-01

    Roč. 21, č. 7 (2004), R1-R5 ISSN 0264-9381 R&D Projects: GA ČR GA205/03/0902; GA AV ČR KSK1048102 Institutional research plan: CEZ:AV0Z1003909 Keywords : black holes * accretion discs * general relativity Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 2.941, year: 2004

  19. The PANDA Endcap Disc DIRC

    Science.gov (United States)

    Föhl, K.; Ali, A.; Belias, A.; Dzhygadlo, R.; Gerhardt, A.; Götzen, K.; Kalicy, G.; Krebs, M.; Lehmann, D.; Nerling, F.; Patsyuk, M.; Peters, K.; Schepers, G.; Schmitt, L.; Schwarz, C.; Schwiening, J.; Traxler, M.; Böhm, M.; Eyrich, W.; Lehmann, A.; Pfaffinger, M.; Uhlig, F.; Düren, M.; Etzelmüller, E.; Hayrapetyan, A.; Kreutzfeld, K.; Merle, O.; Rieke, J.; Schmidt, M.; Wasem, T.; Achenbach, P.; Cardinali, M.; Hoek, M.; Lauth, W.; Schlimme, S.; Sfienti, C.; Thiel, M.

    2018-02-01

    Positively identifying charged kaons in the PANDA forward endcap solid angle range can be achieved with the Endcap Disc DIRC, allowing kaon-pion separation from 1 up to 4 GeV/c with a separation power of at least 3 standard deviations. Design, performance, and components of this DIRC are given, including the recently introduced TOFPET-ASIC based read-out. Results of a prototype operated in a test beam at DESY in 2016 are shown.

  20. Decoherence dynamics of a single spin versus spin ensemble

    NARCIS (Netherlands)

    Dobrovitski, V.V.; Feiguin, A.E.; Awschalom, D.D.; Hanson, R.

    2008-01-01

    We study decoherence of central spins by a spin bath, focusing on the difference between measurement of a single central spin and measurement of a large number of central spins (as found in typical spin-resonance experiments). For a dilute spin bath, the single spin demonstrates Gaussian

  1. The lamppost model: effects of photon trapping, the bottom lamp and disc truncation

    Science.gov (United States)

    Niedźwiecki, Andrzej; Zdziarski, Andrzej A.

    2018-04-01

    We study the lamppost model, in which the primary X-ray sources in accreting black-hole systems are located symmetrically on the rotation axis on both sides of the black hole surrounded by an accretion disc. We show the importance of the emission of the source on the opposite side to the observer. Due to gravitational light bending, its emission can increase the direct (i.e., not re-emitted by the disc) flux by as much as an order of magnitude. This happens for near to face-on observers when the disc is even moderately truncated. For truncated discs, we also consider effects of emission of the top source gravitationally bent around the black hole. We also present results for the attenuation of the observed radiation with respect to that emitted by the lamppost as functions of the lamppost height, black-hole spin and the degree of disc truncation. This attenuation, which is due to the time dilation, gravitational redshift and the loss of photons crossing the black-hole horizon, can be as severe as by several orders of magnitude for low lamppost heights. We also consider the contribution to the observed flux due to re-emission by optically-thick matter within the innermost stable circular orbit.

  2. Radio emission from Sgr A*: pulsar transits through the accretion disc

    Science.gov (United States)

    Christie, I. M.; Petropoulou, M.; Mimica, P.; Giannios, D.

    2017-06-01

    Radiatively inefficient accretion flow models have been shown to accurately account for the spectrum and luminosity observed from Sgr A* in the X-ray regime down to mm wavelengths. However, observations at a few GHz cannot be explained by thermal electrons alone but require the presence of an additional non-thermal particle population. Here, we propose a model for the origin of such a population in the accretion flow via means of a pulsar orbiting the supermassive black hole in our Galaxy. Interactions between the relativistic pulsar wind with the disc lead to the formation of a bow shock in the wind. During the pulsar's transit through the accretion disc, relativistic pairs, accelerated at the shock front, are injected into the disc. The radio-emitting particles are long lived and remain within the disc long after the pulsar's transit. Periodic pulsar transits through the disc result in regular injection episodes of non-thermal particles. We show that for a pulsar with spin-down luminosity Lsd ˜ 3 × 1035 erg s-1 and a wind Lorentz factor of γw ˜ 104 a quasi-steady synchrotron emission is established with luminosities in the 1-10 GHz range comparable to the observed one.

  3. Relativistic reflection from accretion disc ionised due to illumination from on-axis compact corona

    Science.gov (United States)

    Dovciak, M.; Guainazzi, M.; Svoboda, J.

    2014-07-01

    We re-visit the relativistic (light bending) reflection scenario of AGN spectra in the lamp-post geometry. We compute the ionisation of the disc consistently with the amount of illumination from the on-axis compact corona. In this model the ionisation pattern of the disc is dependent on the distance from the centre according to astrophysically-motivated assumptions. We investigate the complementarity of different model parameters like: a) the intrinsic primary flux and the height of the corona, both affecting the normalization of the observed primary power-law; b) the height of the corona and the black hole spin, both affecting the amount of radiation emitted from the innermost regions of the disc; and c) the intrinsic primary flux, the height of the corona and the density of the disc, the three parameters that affect the ionisation state of the disc. We examine how these complementarities manifest themselves when fitting X-ray broadband spectra of the Seyfert 1 Galaxy MCG-6-30-15.

  4. Spin-polarized spin excitation spectroscopy

    International Nuclear Information System (INIS)

    Loth, Sebastian; Lutz, Christopher P; Heinrich, Andreas J

    2010-01-01

    We report on the spin dependence of elastic and inelastic electron tunneling through transition metal atoms. Mn, Fe and Cu atoms were deposited onto a monolayer of Cu 2 N on Cu(100) and individually addressed with the probe tip of a scanning tunneling microscope. Electrons tunneling between the tip and the substrate exchange energy and spin angular momentum with the surface-bound magnetic atoms. The conservation of energy during the tunneling process results in a distinct onset threshold voltage above which the tunneling electrons create spin excitations in the Mn and Fe atoms. Here we show that the additional conservation of spin angular momentum leads to different cross-sections for spin excitations depending on the relative alignment of the surface spin and the spin of the tunneling electron. For this purpose, we developed a technique for measuring the same local spin with a spin-polarized and a non-spin-polarized tip by exchanging the last apex atom of the probe tip between different transition metal atoms. We derive a quantitative model describing the observed excitation cross-sections on the basis of an exchange scattering process.

  5. Magnons, Spin Current and Spin Seebeck Effect

    Science.gov (United States)

    Maekawa, Sadamichi

    2012-02-01

    When metals and semiconductors are placed in a temperature gradient, the electric voltage is generated. This mechanism to convert heat into electricity, the so-called Seebeck effect, has attracted much attention recently as the mechanism for utilizing wasted heat energy. [1]. Ferromagnetic insulators are good conductors of spin current, i.e., the flow of electron spins [2]. When they are placed in a temperature gradient, generated are magnons, spin current and the spin voltage [3], i.e., spin accumulation. Once the spin voltage is converted into the electric voltage by inverse spin Hall effect in attached metal films such as Pt, the electric voltage is obtained from heat energy [4-5]. This is called the spin Seebeck effect. Here, we present the linear-response theory of spin Seebeck effect based on the fluctuation-dissipation theorem [6-8] and discuss a variety of the devices. [4pt] [1] S. Maekawa et al, Physics of Transition Metal Oxides (Springer, 2004). [0pt] [2] S. Maekawa: Nature Materials 8, 777 (2009). [0pt] [3] Concept in Spin Electronics, eds. S. Maekawa (Oxford University Press, 2006). [0pt] [4] K. Uchida et al., Nature 455, 778 (2008). [0pt] [5] K. Uchida et al., Nature Materials 9, 894 (2010) [0pt] [6] H. Adachi et al., APL 97, 252506 (2010) and Phys. Rev. B 83, 094410 (2011). [0pt] [7] J. Ohe et al., Phys. Rev. B (2011) [0pt] [8] K. Uchida et al., Appl. Phys. Lett. 97, 104419 (2010).

  6. Optic Disc Identification Methods for Retinal Images

    Directory of Open Access Journals (Sweden)

    Florin Rotaru

    2014-07-01

    Full Text Available Presented are the methods proposed by authors to identify and model the optic disc in colour retinal images. The first three our approaches localized the optic disc in two steps: a in the green component of RGB image the optic disc area is detected based on texture indicators and pixel intensity variance analysis; b on the segmented area the optic disc edges are extracted and the resulted boundary is approximated by a Hough transform. The last implemented method identifies the optic disc area by analysis of blood vessels network extracted in the green channel of the original image. In the segmented area the optic disc edges are obtained by an iterative Canny algorithm and are approximated by a circle Hough transform.

  7. Biomaterials for intervertebral disc regeneration and repair.

    Science.gov (United States)

    Bowles, Robert D; Setton, Lori A

    2017-06-01

    The intervertebral disc contributes to motion, weight bearing, and flexibility of the spine, but is susceptible to damage and morphological changes that contribute to pathology with age and injury. Engineering strategies that rely upon synthetic materials or composite implants that do not interface with the biological components of the disc have not met with widespread use or desirable outcomes in the treatment of intervertebral disc pathology. Here we review bioengineering advances to treat disc disorders, using cell-supplemented materials, or acellular, biologically based materials, that provide opportunity for cell-material interactions and remodeling in the treatment of intervertebral disc disorders. While a field still in early development, bioengineering-based strategies employing novel biomaterials are emerging as promising alternatives for clinical treatment of intervertebral disc disorders. Copyright © 2017 Elsevier Ltd. All rights reserved.

  8. Eccentricity evolution during planet-disc interaction

    Science.gov (United States)

    Ragusa, Enrico; Rosotti, Giovanni; Teyssandier, Jean; Booth, Richard; Clarke, Cathie J.; Lodato, Giuseppe

    2018-03-01

    During the process of planet formation, the planet-disc interactions might excite (or damp) the orbital eccentricity of the planet. In this paper, we present two long (t ˜ 3 × 105 orbits) numerical simulations: (a) one (with a relatively light disc, Md/Mp = 0.2), where the eccentricity initially stalls before growing at later times and (b) one (with a more massive disc, Md/Mp = 0.65) with fast growth and a late decrease of the eccentricity. We recover the well-known result that a more massive disc promotes a faster initial growth of the planet eccentricity. However, at late times the planet eccentricity decreases in the massive disc case, but increases in the light disc case. Both simulations show periodic eccentricity oscillations superimposed on a growing/decreasing trend and a rapid transition between fast and slow pericentre precession. The peculiar and contrasting evolution of the eccentricity of both planet and disc in the two simulations can be understood by invoking a simple toy model where the disc is treated as a second point-like gravitating body, subject to secular planet-planet interaction and eccentricity pumping/damping provided by the disc. We show how the counterintuitive result that the more massive simulation produces a lower planet eccentricity at late times can be understood in terms of the different ratios of the disc-to-planet angular momentum in the two simulations. In our interpretation, at late times the planet eccentricity can increase more in low-mass discs rather than in high-mass discs, contrary to previous claims in the literature.

  9. Intradural cervical disc herniation: a case report

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Seung Eun; Lee, Sang Ho; Jo, Byung June; Yoon, Deug Hee [Wooridul Spine Hospital, Seoul (Korea, Republic of); Kim, Tae Hong [Inje University College of Medicine, Inje (Korea, Republic of)

    2005-07-15

    Intradural cervical disc herniation is an extremely rare condition and its pathogenesis is not certain. We experienced a case of intradural cervical disc herniation at the C4-5 level in a 56-year-old man. The preoperative sagittal T1- and T2- weighted images revealed an intradural iso-intensity lesion, with the spinal cord behind the posterior longitudinal ligament at the C4-5 disc level. The post-contrast T1-weighted image revealed a peripheral enhanced intradural lesion. We report here on a case of an intradural cervical disc herniation that was diagnosed by radiological examination, and we include a review of the related literature.

  10. Computed tomography in lumbar herniated disc

    Energy Technology Data Exchange (ETDEWEB)

    Choi, Chul Soon; Chang, Kee Hyun; Han, Man Chung [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1984-09-15

    197 spine CTs were performed from 29th , March 1982 to 7th March, 1984. Among them, 39 patients preoperatively diagnosed as herniated nucleus pulposus or bulging disc with CT and myelography were operated. 43 disc spaces of disc disease are analysed in true positive and false negative cases. Finally the accuracy, sensitivity and specificity of spine CT and myelography are calculated. The results are as follows: 1. The CT findings of disc diseases are in order of frequency, asymmetrical obliteration of epidural fat (82%) , ventral indentation or compression on dural sac (72%), focal protrusion of disc (64%), root changes - obliteration, displacement, compression, non-filling of metrizamide - (54%), diffuse disc bulging (36%), disc at body level (31%), disc calcifications (26%), disc vacuum (10%) and other associated findings - spinal stenosis, foraminal stenosis, ligament flavum thickening, facet joint hypertrophy (26%). 2. Sensitivities of spine CT and myelography are 95% and 94%, specificities are 67%, 50% and overall accuracies 93%, 87%, respectively. 3. Therefore, it is recommended that the spine CT be used as a primary diagnostic method and the myelography as a secondary complementary study when the CT gives no conclusive findings.

  11. Debris disc constraints on planetesimal formation

    Science.gov (United States)

    Krivov, Alexander V.; Ide, Aljoscha; Löhne, Torsten; Johansen, Anders; Blum, Jürgen

    2018-02-01

    Two basic routes for planetesimal formation have been proposed over the last decades. One is a classical `slow-growth' scenario. Another one is particle concentration models, in which small pebbles are concentrated locally and then collapse gravitationally to form planetesimals. Both types of models make certain predictions for the size spectrum and internal structure of newly born planetesimals. We use these predictions as input to simulate collisional evolution of debris discs left after the gas dispersal. The debris disc emission as a function of a system's age computed in these simulations is compared with several Spitzer and Herschel debris disc surveys around A-type stars. We confirm that the observed brightness evolution for the majority of discs can be reproduced by classical models. Further, we find that it is equally consistent with the size distribution of planetesimals predicted by particle concentration models - provided the objects are loosely bound `pebble piles' as these models also predict. Regardless of the assumed planetesimal formation mechanism, explaining the brightest debris discs in the samples uncovers a `disc mass problem'. To reproduce such discs by collisional simulations, a total mass of planetesimals of up to ˜1000 Earth masses is required, which exceeds the total mass of solids available in the protoplanetary progenitors of debris discs. This may indicate that stirring was delayed in some of the bright discs, that giant impacts occurred recently in some of them, that some systems may be younger than previously thought or that non-collisional processes contribute significantly to the dust production.

  12. Study of the operational parameters of crops turbine sprayer (turbo liner on spray quality and diameter of droplets, using image processing

    Directory of Open Access Journals (Sweden)

    F Behzadi Pour

    2017-05-01

    Full Text Available Introduction Today, attention to safety and environmental issues in all sectors in agriculture, industry and services is very important. Chemical poisons play an important role in rapid progress of agricultural products. Every year about 25 to 35 percent of the world's crops are affected by insects, weeds and plant pathogens disappear and this figure would be raised to 80% if no control was applied. Drift problem and its devastating effects are the most important issue which related to users and sprayers manufacturers. Spray drift reduction and improvements in the efficiency of pesticide application processes are global goals. Where ever spraying is applied, drift will be produced and it must be controlled by controlled of the droplet size. The application of these sprayers is the high in the farms (the number of 2303 in Iran. So, this research was carried out to improve the quality of work in these sprayers by studying the droplets diameter and the spray quality index. Materials and Methods The research was conducted at the University of Khouzestan Ramin Agriculture and Natural Resources. Tests were done with 20 m of water sensitive papers at a distance of 2 meters from each other. To evaluate the technical items affecting on drift, an experiment was conducted using a turbo liner sprayer (TURBINA S.A. 800 and the John Deer (JD 3140 tractor. A completely randomized factorial design was applied. By using 3 replications and the factors were spraying pressure applying three levels (10, 25 and 35 bar, the fan speed with two levels (1998 and 2430 rpm and forward speed with two levels (9 and 13.5 km hr-1. The sprayer started the application, spraying a solution of water and tracer (yellow Tartrazine E 102, 15m before the water sensitive papers and then moved over the water sensitive papers. The spraying was continued 15 m after the end of the sampling area. After spraying, sensitive papers were photographed and then volume diameter of 50% (DV50 and

  13. Total Disc Replacement in Lumbar Degenerative Disc Diseases.

    Science.gov (United States)

    Park, Chun Kun

    2015-11-01

    More than 10 years have passed since lumbar total disc replacement (LTDR) was introduced for the first time to the world market for the surgical management of lumbar degenerative disc disease (DDD). It seems like the right time to sum up the relevant results in order to understand where LTDR stands on now, and is heading forward to. The pathogenesis of DDD has been currently settled, but diagnosis and managements are still controversial. Fusion is recognized as golden standard of surgical managements but has various kinds of shortcomings. Lately, LTDR has been expected to replace fusion surgery. A great deal of LTDR reports has come out. Among them, more than 5-year follow-up prospective randomized controlled studies including USA IDE trials were expected to elucidate whether for LTDR to have therapeutic benefit compared to fusion. The results of these studies revealed that LTDR was not inferior to fusion. Most of clinical studies dealing with LTDR revealed that there was no strong evidence for preventive effect of LTDR against symptomatic degenerative changes of adjacent segment disease. LTDR does not have shortcomings associated with fusion. However, it has a potentiality of the new complications to occur, which surgeons have never experienced in fusion surgeries. Consequently, longer follow-up should be necessary as yet to confirm the maintenance of improved surgical outcome and to observe any very late complications. LTDR still may get a chance to establish itself as a substitute of fusion both nominally and virtually if it eases the concerns listed above.

  14. Total Disc Arthroplasty for Treating Lumbar Degenerative Disc Disease

    Science.gov (United States)

    2015-01-01

    Study Design Lumber disc arthroplasty is a technological advancement that has occurred in the last decade to treat lumbar degenerative disk diseases. Purpose The aim of this retrospective study was to establish the impact and outcomes of managing patients with lumbar degenerative disk disease who have been treated with lumbar total disc arthroplasty (TDA). Overview of Literature Several studies have shown promising results following this surgery. Methods We reviewed the files of 104 patients at the Department of Neurosurgery in Colmar (France) who had been operated on by lumbar spine arthroplasty (Prodisc) between April 2002 and October 2008. Results Among the 104 patients, 67 were female and 37 were male with an average age of 33.1 years. We followed the cases for a mean of 20 months. The most frequent level of discopathy was L4-L5 with 62 patients (59.6%) followed by L5-S1 level with 52 patients (50%). Eighty-three patients suffered from low back pain, 21 of which were associated with radiculopathy. The status of 82 patients improved after surgery according to the Oswestry Disability Index score, and 92 patients returned to work. Conclusions The results indicate that TDA is a good alternative treatment for lumbar spine disk disease, particularly for patients with disabling and chronic low back pain. This technique contributes to improve living conditions with correct patient selection for surgery. PMID:25705336

  15. Spin-Mechatronics

    Science.gov (United States)

    Matsuo, Mamoru; Saitoh, Eiji; Maekawa, Sadamichi

    2017-01-01

    We investigate the interconversion phenomena between spin and mechanical angular momentum in moving objects. In particular, the recent results on spin manipulation and spin-current generation by mechanical motion are examined. In accelerating systems, spin-dependent gauge fields emerge, which enable the conversion from mechanical angular momentum into spins. Such a spin-mechanical effect is predicted by quantum theory in a non-inertial frame. Experiments which confirm the effect, i.e., the resonance frequency shift in nuclear magnetic resonance, the stray field measurement of rotating metals, and electric voltage generation in liquid metals, are discussed.

  16. Experimental Research on the Impact of Thin-Wall Ratio and the Fillet Radius of Forming Roller on the Limiting Spinning Ratio of AMS 5504 Sheets

    Directory of Open Access Journals (Sweden)

    Kut S.

    2017-12-01

    Full Text Available Results of experimental investigations of metal spinning process of AMS 5504 sheets. cylindrical drawpieces with use of discs-shaped sheet with various diameter and thickness were shown in this work. Tests were performed on two roller metal spinning machine of a vertical axis Leifeld SFC 800 V500.

  17. Use NASA GES DISC Data in ArcGIS

    Science.gov (United States)

    Yang, Wenli; Pham, Long B.; Kempler, Steve

    2015-01-01

    This presentation describes GIS relevant data at NASA Goddard Earth Sciences Data and Information Services Center (GES DISC), GES DISC Services and Support for GIS Users, and use cases of GES DISC data in ArcGIS.

  18. Minimum weight design of inhomogeneous rotating discs

    International Nuclear Information System (INIS)

    Jahed, Hamid; Farshi, Behrooz; Bidabadi, Jalal

    2005-01-01

    There are numerous applications for gas turbine discs in the aerospace industry such as in turbojet engines. These discs normally work under high temperatures while subjected to high angular velocities. Minimizing the weight of such items in aerospace applications results in benefits such as low dead weights and lower costs. High speed of rotation causes large centrifugal forces in a disc and simultaneous application of high temperatures reduces disc material strength. Thus, the latter effects tend to increase deformations of the disc under the applied loads. In order to obtain a reliable disc analysis and arrive at the corresponding correct stress distribution, solutions should consider changes in material properties due to the temperature field throughout the disc. To achieve this goal, an inhomogeneous disc model with variable thickness is considered. Using the variable material properties method, stresses are obtained for the disc under rotation and a steady temperature field. In this paper this is done by modelling the rotating disc as a series of rings of different but constant properties. The optimum disc profile is arrived at by sequentially proportioning the thicknesses of each ring to satisfy the stress requirements. This method vis-a-vis a mathematical programming procedure for optimization shows several advantages. Firstly, it is simple iterative proportioning in each design cycle not requiring involved mathematical operations. Secondly, due to its simplicity it alleviates the necessity of certain simplifications that are common in so-called rigorous mathematical procedures. The results obtained, compared to those published in the literature show agreement and superiority. A further advantage of the proposed method is the independence of the end results from the initially assumed point in the iterative design routine, unlike most methods published so far

  19. Optical, Nanomechanical and Electrochemical Sensing on a DVD Disc

    DEFF Research Database (Denmark)

    Boisen, Anja

    2014-01-01

    -like sensors have been integrated on a disc [2] and we now have a method of obtaining large amount of data – allowing us to do statistics on the measurements. Currently, we are studying the specific detection of biomarkers, such as suPAR [3]. Additionally, we try to implement optical microscopy on the spinning...... combined with sensitive and compact read-out possibilities from optical pick-up heads makes it possible to realize full sample pretreatment and read-out in a both fast and compact manner. References: 1. M. Madou et al., Lab on a CD, Annual Review of Biomedical Engineering, Vol. 8: 601-628, 2016 2. F......Our vision is to create a platform where optical, nanomecanical and electrochemical sensors can be integrated and read-out using the mechanics and the optics from DVDs and Blu-Rays. Integrating sensors on a disc allows us to use centrifugal microfluidis which has been developed for more than 50...

  20. Two-dimensional spin diffusion in multiterminal lateral spin valves

    Science.gov (United States)

    Saha, D.; Basu, D.; Holub, M.; Bhattacharya, P.

    2008-01-01

    The effects of two-dimensional spin diffusion on spin extraction in lateral semiconductor spin valves have been investigated experimentally and theoretically. A ferromagnetic collector terminal of variable size is placed between the ferromagnetic electron spin injector and detector of a conventional lateral spin valve for spin extraction. It is observed that transverse spin diffusion beneath the collector terminal plays an important role along with the conventional longitudinal spin diffusion in describing the overall transport of spin carriers. Two-dimensional spin diffusion reduces the perturbation of the channel electrochemical potentials and improves spin extraction.

  1. Changes in disc herniation after CT-guided Percutaneous Laser Disc Decompression (PLDD): MR findings

    Science.gov (United States)

    Brat, Hugues G.; Bouziane, Tarik; Lambert, Jean; Divano, Luisa

    2004-09-01

    The aim of Percutaneous Laser Disc Decompression (PLDD) is to vaporize a small portion of the nucleus pulposus. Clinical efficacy of this technique is largely proven. However, time-evolution of intervertebral disc and its hernia after PLDD is not known. This study analyses changes in disc herniation and its native intervertebral disc at a mean follow-up of 7.5 months after PLDD in asymptomatic patients. Main observations at MRI are appearance of a high signal on T2WI in the hernia in 59%, shrinking of the hernia in 66% and overall stability of disc height.

  2. Thoracic disc herniation: Surgical treatment.

    Science.gov (United States)

    Court, C; Mansour, E; Bouthors, C

    2018-02-01

    Thoracic disc herniation is rare and mainly occurs between T8 and L1. The herniation is calcified in 40% of cases and is labeled as giant when it occupies more than 40% of the spinal canal. A surgical procedure is indicated when the patient has severe back pain, stubborn intercostal neuralgia or neurological deficits. Selection of the surgical approach is essential. Mid-line calcified hernias are approached from a transthoracic incision, while lateralized soft hernias can be approached from a posterolateral incision. The complication rate for transthoracic approaches is higher than that of posterolateral approaches; however, the former are performed in more complex herniation cases. The thoracoscopic approach is less invasive but has a lengthy learning curve. Retropleural mini-thoracotomy is a potential compromise solution. Fusion is recommended in cases of multilevel herniation, herniation in the context of Scheuermann's disease, when more than 50% bone is resected from the vertebral body, in patients with preoperative back pain or herniation at the thoracolumbar junction. Along with complications specific to the surgical approach, the surgical risks are neurological worsening, dural breach and subarachnoid-pleural fistulas. Giant calcified herniated discs are the largest contributor to myelopathy, intradural extension and postoperative complications. Some of the technical means that can be used to prevent complications are explored, along with how to address these complications. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  3. Optic Disc Drusen in Children

    DEFF Research Database (Denmark)

    Malmqvist, Lasse; Li, Xiao Qiang; Eckmann, Christina L

    2017-01-01

    diameter and fetal birth and pubertal parameters are associated with the presence of ODD. METHODS: This observational, longitudinal population-based birth cohort study, with a nested case-control, included 1,406 children. Eye examinations were performed when the children were between 11 and 12 years of age....... Assessment was performed of optical coherence tomography (OCT) scans from 1,304 children with gradable enhanced depth imaging scans of the optic disc. RESULTS: ODD in one or both eyes were found in 13 (1.0%) of all children. All but one of the cases were found in children with scleral canal diameter...... in the lowest quartile (1,182-1,399 μm) in the nested case-control study. Children with ODD had a mean disc diameter of 1,339 μm (interquartile range, 30 μm), whereas it was 1,508 μm (interquartile range, 196 μm) in the 130 controls without ODD (P

  4. Cervical disc hernia operations through posterior laminoforaminotomy

    OpenAIRE

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients ...

  5. Computing Decoupled Residuals for Compact Disc Players

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

    2006-01-01

    In order to improve Compact Disc Players playability regarding playing Compact Discs with surface faults, like scratches and fingerprints etc, the attention has been put on fault tolerant control schemes. Almost every of those methods are based on fault detection. The standard approach is to use...

  6. Genetic association studies in lumbar disc degeneration

    DEFF Research Database (Denmark)

    Eskola, Pasi J; Lemmelä, Susanna; Kjaer, Per

    2012-01-01

    Low back pain is associated with lumbar disc degeneration, which is mainly due to genetic predisposition. The objective of this study was to perform a systematic review to evaluate genetic association studies in lumbar disc degeneration as defined on magnetic resonance imaging (MRI) in humans....

  7. The Actual Level of Symptomatic Soft Disc Herniation in Patients with Cervical Disc Herniation.

    Science.gov (United States)

    Choi, Su Yong; Lee, Sang Gu; Kim, Woo Kyung; Son, Seong; Jeong, Tae Seok

    2015-09-01

    The aim of this study was to predict the relationship between the symptomatic disc herniation level and the osteophyte level or decreased disc height in patients with cervical disc herniation. Between January 2011 and December 2012, 69 patients with an osteophyte of the cervical spine underwent surgery at a single center due to soft cervical disc herniation. Data including soft disc herniation level, osteophyte level in the posterior vertebral margin, Cobb's angle, and symptom duration were retrospectively assessed. The patients were divided into three groups according to the relationship between the degenerative change level and the level of reported symptoms. Among the 69 patients, 48 (69.6%) showed a match between osteophyte level and soft disc herniation level. Disc herniation occurred at the adjacent segment to degenerative osteophyte level in 12 patients (17.4%) and at both the adjacent and the osteophyte level in nine (13.0%). There was no significant difference in Cobb's angle or duration among the three groups. Osteophyte type was not significant. The mean disc height of the prominent degenerative change level group was lower than the adjacent segment level, but this was not significant. Soft cervical disc herniation usually occurs at the level an osteophyte forms. However, it may also occur at segments adjacent to that of the osteophyte level. Therefore, in patients with cervical disc herniation, although a prominent osteophyte alone may appear on plain radiography, we must suspect the presence of soft disc herniation at other levels.

  8. Dynamic nuclear spin polarization

    Energy Technology Data Exchange (ETDEWEB)

    Stuhrmann, H.B. [GKSS-Forschungszentrum Geesthacht GmbH (Germany)

    1996-11-01

    Polarized neutron scattering from dynamic polarized targets has been applied to various hydrogenous materials at different laboratories. In situ structures of macromolecular components have been determined by nuclear spin contrast variation with an unprecedented precision. The experiments of selective nuclear spin depolarisation not only opened a new dimension to structural studies but also revealed phenomena related to propagation of nuclear spin polarization and the interplay of nuclear polarisation with the electronic spin system. The observation of electron spin label dependent nuclear spin polarisation domains by NMR and polarized neutron scattering opens a way to generalize the method of nuclear spin contrast variation and most importantly it avoids precontrasting by specific deuteration. It also likely might tell us more about the mechanism of dynamic nuclear spin polarisation. (author) 4 figs., refs.

  9. Regression of a symptomatic thoracic disc herniation with a calcified intervertebral disc component

    Directory of Open Access Journals (Sweden)

    Hidayet Sari

    2016-12-01

    Full Text Available There were only a few cases describing spontaneous regression of calcified thoracic disc herniation in the literature. We present a 38-year-old male office worker who had left paramedian-foraminal extruded disc at T7–T8 with calcifications of the T7–T8 and T8–T9 intervertebral discs. This case was unique in that the non-calcified extruded disc material regressed almost completely in 5 months while the calcified intervertebral discs remained the same during the process of regression. This report stresses that regression of the herniated material of the thoracic discs with subsidence of the symptoms is still possible even if the disc material is calcified.

  10. Design and Development of Micro-Power Generating Device for Biomedical Applications of Lab-on-a-Disc.

    Directory of Open Access Journals (Sweden)

    Karunan Joseph

    Full Text Available The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc's rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film's vibration during the disc's rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62 °C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms.

  11. Lumbar disc cyst with contralateral radiculopathy

    Directory of Open Access Journals (Sweden)

    Kishore Tourani

    2012-08-01

    Full Text Available Disc cysts are uncommon intraspinal cystic lesions located in the ventrolateral epidural space. They communicate with the nucleus pulposus of the intervertebral disc and cause symptoms by radicular compression. We report a unique case of lumbar disc cyst that was associated with disc herniation and contralateral radiculopathy. A 22 year old male presented with one month history of back-ache radiating to the left leg. Magnetic Resonance Imaging (MRI showed L3-L4 disc herniation with annular tear and cystic lesion in the extradural space anterior to the thecal sac on right side, which increased in size over a period of 3 weeks. L3 laminectomy and bilateral discectomy and cyst excision was done with partial improvement of patients symptoms.

  12. Spontaneous Regression of Lumbar Herniated Disc

    Directory of Open Access Journals (Sweden)

    Chun-Wei Chang

    2009-12-01

    Full Text Available Intervertebral disc herniation of the lumbar spine is a common disease presenting with low back pain and involving nerve root radiculopathy. Some neurological symptoms in the majority of patients frequently improve after a period of conservative treatment. This has been regarded as the result of a decrease of pressure exerted from the herniated disc on neighboring neurostructures and a gradual regression of inflammation. Recently, with advances in magnetic resonance imaging, many reports have demonstrated that the herniated disc has the potential for spontaneous regression. Regression coincided with the improvement of associated symptoms. However, the exact regression mechanism remains unclear. Here, we present 2 cases of lumbar intervertebral disc herniation with spontaneous regression. We review the literature and discuss the possible mechanisms, the precipitating factors of spontaneous disc regression and the proper timing of surgical intervention.

  13. Magnetic resonance imaging of intervertebral disc degeneration

    International Nuclear Information System (INIS)

    Maeda, Hiroshi; Noguchi, Masao; Kira, Hideaki; Fujiki, Hiroshi; Shimokawa, Isao; Hinoue, Kaichi.

    1993-01-01

    The aim of this study was to correlate the degree of lumbar intervertebral disc degeneration with findings of magnetic resonance imaging (MRI). Seventeen autopsied (from 7 patients) and 21 surgical (from 20 patients) intervertebral discs were used as specimens for histopathological examination. In addition, 21 intervertebral discs were examined on T2-weighted images. Histopathological findings from both autopsied and surgical specimens were well correlated with MRI findings. In particular, T2-weighted images reflected increased collagen fibers and rupture within the fibrous ring accurately. However, when severely degenerated intervertebral discs and hernia protruding the posterior longitudinal ligament existed, histological findings were not concordant well with T2-weighted images. Morphological appearances of autopsy specimens, divided into four on T2-weighted images, were well consistent with histological degeneration. This morphological classification, as shown on T2-weighted images, could also be used in the evaluation of intervertebral disc degeneration. (N.K.)

  14. Magnetic resonance imaging of intervertebral disc degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Maeda, Hiroshi; Noguchi, Masao (Kitakyushu City Yahata Hospital, Fukuoka (Japan)); Kira, Hideaki; Fujiki, Hiroshi; Shimokawa, Isao; Hinoue, Kaichi

    1993-02-01

    The aim of this study was to correlate the degree of lumbar intervertebral disc degeneration with findings of magnetic resonance imaging (MRI). Seventeen autopsied (from 7 patients) and 21 surgical (from 20 patients) intervertebral discs were used as specimens for histopathological examination. In addition, 21 intervertebral discs were examined on T2-weighted images. Histopathological findings from both autopsied and surgical specimens were well correlated with MRI findings. In particular, T2-weighted images reflected increased collagen fibers and rupture within the fibrous ring accurately. However, when severely degenerated intervertebral discs and hernia protruding the posterior longitudinal ligament existed, histological findings were not concordant well with T2-weighted images. Morphological appearances of autopsy specimens, divided into four on T2-weighted images, were well consistent with histological degeneration. This morphological classification, as shown on T2-weighted images, could also be used in the evaluation of intervertebral disc degeneration. (N.K.).

  15. The formation of planets by disc fragmentation

    Directory of Open Access Journals (Sweden)

    Stamatellos Dimitris

    2013-04-01

    Full Text Available I discuss the role that disc fragmentation plays in the formation of gas giant and terrestrial planets, and how this relates to the formation of brown dwarfs and low-mass stars, and ultimately to the process of star formation. Protostellar discs may fragment, if they are massive enough and can cool fast enough, but most of the objects that form by fragmentation are brown dwarfs. It may be possible that planets also form, if the mass growth of a proto-fragment is stopped (e.g. if this fragment is ejected from the disc, or suppressed and even reversed (e.g by tidal stripping. I will discuss if it is possible to distinguish whether a planet has formed by disc fragmentation or core accretion, and mention of a few examples of observed exoplanets that are suggestive of formation by disc fragmentation.

  16. Solar neighbourhood and Galactic disc(s: New constraints

    Directory of Open Access Journals (Sweden)

    Schönrich R.

    2012-02-01

    Full Text Available We present a re-analysis of the Geneva-Copenhagen survey, based on improved effective temperature and metallicity scales, which also provide a better match to theoretical isochrones. The latter are used for a Bayesian investigation on stellar ages. With respect to previous analyses, our stars are on average 100 K hotter and 0.1 dex more metal rich, which shifts the peak of the metallicity distribution function around the solar value. From Strömgren photometry we are able to derive for the first time a proxy for alpha elements, which enables us to perform a tentative dissection of the chemical thin and thick disc. We find evidence for the latter being composed of an old, mildly but systematically alpha-enhanced population that extends to super solar metallicities, in agreement with spectroscopic studies. Our analysis suggests a strong interplay among ages, abundances and kinematics of stars.

  17. Spin at Lausanne

    International Nuclear Information System (INIS)

    Anon.

    1980-01-01

    From 25 September to 1 October, some 150 spin enthusiasts gathered in Lausanne for the 1980 International Symposium on High Energy Physics with Polarized Beams and Polarized Targets. The programme was densely packed, covering physics interests with spin as well as the accelerator and target techniques which make spin physics possible

  18. Spin-torque transistor

    NARCIS (Netherlands)

    Bauer, G.E.W.; Brataas, A.; Tserkovnyak, Y.; Van Wees, B.J.

    2003-01-01

    A magnetoelectronic thin-film transistor is proposed that can display negative differential resistance and gain. The working principle is the modulation of the soure–drain current in a spin valve by the magnetization of a third electrode, which is rotated by the spin-torque created by a control spin

  19. MR guidance and thermometry of percutaneous laser disc decompression in open MRI: an ex vivo study.

    Science.gov (United States)

    Streitparth, Florian; Walter, Thula; Wonneberger, Uta; Schnackenburg, Bernhard; Philipp, Carsten M; Collettini, Federico; Teichgräber, Ulf K M; Gebauer, Bernhard

    2014-06-01

    To assess the feasibility of guidance and thermometry by open 1.0 T magnetic resonance (MR) imaging during percutaneous laser disc decompression (PLDD). A fluoroscopic proton-density-weighted turbo spin echo sequence was used for positioning a laser fiber and a reference thermosensor within the targeted spinal disc. In 30 lumbar discs from human donors, nonspoiled gradient-echo (GRE) sequences with different echo times (TE) were compared to monitor thermal laser effects (Nd:YAG laser, 1,064 nm). Temperature distribution was visualized in real time on the basis of T1-weighted images and the proton resonance frequency (PRF) technique. Image quality, temperature accuracy, and correlation with macroscopic lesion sizes were analyzed. Image quality was confirmed in healthy volunteers. MR-guided placement of the laser fiber in the center of the targeted disk was precise. Best overall PLDD results-considering image quality (contrast-to-noise ratio), temperature accuracy (R (2) = 0.96), and correlation between the macroscopic and MR lesions (R (2) = 0.63)-were achieved with TE at 7 ms. The same TE value also gave the best image quality with healthy volunteers. Instrument guidance and PRF-based thermometry of PLDD in the lumbar spine are feasible and accurate. Open 1.0 T MR imaging with fast spin-echo and GRE sequence designs may render laser discectomies more effective and controllable.

  20. Spin physics in semiconductors

    CERN Document Server

    2017-01-01

    This book offers an extensive introduction to the extremely rich and intriguing field of spin-related phenomena in semiconductors. In this second edition, all chapters have been updated to include the latest experimental and theoretical research. Furthermore, it covers the entire field: bulk semiconductors, two-dimensional semiconductor structures, quantum dots, optical and electric effects, spin-related effects, electron-nuclei spin interactions, Spin Hall effect, spin torques, etc. Thanks to its self-contained style, the book is ideally suited for graduate students and researchers new to the field.

  1. [Physiotherapy in lumbar disc herniation ].

    Science.gov (United States)

    Stoll, T; Germann, D; Hagmann, H

    2001-08-01

    Physiotherapy is the treatment of choice in patients with symptoms caused by a lumbar disc herniation. In clinical practice a broad range of physiotherapeutic modalities has been revealed to be helpful. During the acute stage the efficacy of the McKenzie-concept, mobilisation therapies and traction has been demonstrated in randomized controlled trials with a blind assessor. In addition, pain reducing physical therapies such as cold or electrotherapy and non-steroidal anti-inflammatory drugs, analgesics and/or muscle relaxants are sensible initial accompanying treatments. The effectiveness of active physiotherapies such as training of local strength endurance of back and abdominal muscles has been proven in patients during the chronic stage. The indications for a in-patient rehabilitation programme, for surgery and the danger of developing chronic low back pain are discussed.

  2. Spontaneous Regression of Herniated Lumbar Disc with New Disc Protrusion in the Adjacent Level.

    Science.gov (United States)

    Hakan, Tayfun; Gürcan, Serkan

    2016-01-01

    Spontaneous regression of herniated lumbar discs was reported occasionally. The mechanisms proposed for regression of disc herniation are still incomplete. This paper describes and discusses a case of spontaneous regression of herniated lumbar discs with a new disc protrusion in the adjacent level. A 41-year-old man was admitted with radiating pain and numbness in the left lower extremity with a left posterolateral disc extrusion at L5-S1 level. He was admitted to hospital with low back pain due to disc herniation caudally immigrating at L4-5 level three years ago. He refused the surgical intervention that was offered and was treated conservatively at that time. He had no neurological deficit and a history of spontaneous regression of the extruded lumbar disc; so, a conservative therapy, including bed rest, physical therapy, nonsteroidal anti-inflammatory drugs, and analgesics, was advised. In conclusion, herniated lumbar disc fragments may regress spontaneously. Reports are prone to advise conservative treatment for extruded or sequestrated lumbar disc herniations. However, these patients should be followed up closely; new herniation at adjacent/different level may occur. Furthermore, it is important to know which herniated disk should be removed and which should be treated conservatively, because disc herniation may cause serious complications as muscle weakness and cauda equine syndrome.

  3. Lumbar herniated disc: spontaneous regression.

    Science.gov (United States)

    Altun, Idiris; Yüksel, Kasım Zafer

    2017-01-01

    Low back pain is a frequent condition that results in substantial disability and causes admission of patients to neurosurgery clinics. To evaluate and present the therapeutic outcomes in lumbar disc hernia (LDH) patients treated by means of a conservative approach, consisting of bed rest and medical therapy. This retrospective cohort was carried out in the neurosurgery departments of hospitals in Kahramanmaraş city and 23 patients diagnosed with LDH at the levels of L3-L4, L4-L5 or L5-S1 were enrolled. The average age was 38.4 ± 8.0 and the chief complaint was low back pain and sciatica radiating to one or both lower extremities. Conservative treatment was administered. Neurological examination findings, durations of treatment and intervals until symptomatic recovery were recorded. Laségue tests and neurosensory examination revealed that mild neurological deficits existed in 16 of our patients. Previously, 5 patients had received physiotherapy and 7 patients had been on medical treatment. The number of patients with LDH at the level of L3-L4, L4-L5, and L5-S1 were 1, 13, and 9, respectively. All patients reported that they had benefit from medical treatment and bed rest, and radiologic improvement was observed simultaneously on MRI scans. The average duration until symptomatic recovery and/or regression of LDH symptoms was 13.6 ± 5.4 months (range: 5-22). It should be kept in mind that lumbar disc hernias could regress with medical treatment and rest without surgery, and there should be an awareness that these patients could recover radiologically. This condition must be taken into account during decision making for surgical intervention in LDH patients devoid of indications for emergent surgery.

  4. Minimizing cryopreservation-induced loss of disc cell activity for storage of whole intervertebral discs

    Directory of Open Access Journals (Sweden)

    SCW Chan

    2010-06-01

    Full Text Available Severe intervertebral disc (IVD degeneration often requires disc excision and spinal fusion, which leads to loss of spinal segment mobility. Implantation of an allograft disc or tissue engineered disc construct emerges as an alternative to artificial disc replacement for preserving the motion of the degenerated level. Establishment of a bank of cadaveric or engineered cryopreserved discs enables size matching, and facilitates clinical management. However, there is a lack of understanding of the behaviour of disc cells during cryopreservation, as well as how to maximize their survival, such that disc graft properties can be preserved. Here, we report on the effect of alterations in cooling rates, cryoprotective agents (CPAs, and duration of pre-cryopreservation incubation in CPA on cellular activity in whole porcine lumbar discs. Our results indicated that cooling rates of -0.3°C/min and -0.5°C /min resulted in the least loss of metabolic activity in nucleus pulposus (NP and annulus fibrosus (AF respectively, while metabolic activity is best maintained by using a combination of 10% dimethylsulphoxide (DMSO and 10% propylene-glycol (PG as CPA. By the use of such parameters, metabolic activity of the NP and the AF cells could be maintained at 70% and 45%, respectively, of that of the fresh tissue. Mechanical testing and histological evaluation showed no significant differences in mechanical properties or alterations in disc structure compared to fresh discs. Despite the limitations of the animal model, our findings provide a framework for establishing an applicable cryopreservation protocol for human disc allografts or tissue-engineered disc constructs.

  5. Intervertebral Disc Characteristic on Progressive Neurological Deficit

    Directory of Open Access Journals (Sweden)

    Farid Yudoyono

    2017-09-01

    Full Text Available Objective: To examine the intervertebral disc characteristic on magnetic resonance imaging (MRI in lumbar herniated disc (LHD patients with progressive neurological deficit. Methods: Patients were collected retrospectively from Dr. Hasan Sadikin General Hospital Database from 2011–2013 with LHD, had neurological deficit such as radiculopathy and cauda equine syndrome for less than four weeks with a positive sign confirmed by neurological examination and confirmatory with MRI examination. Results: A total of 14 patients with lumbar herniated disc disease (10 males, 4 females suffered from progressive neurological deficit with an average age of (52.07±10.9 years old. Early disc height was 9.38±0.5 mm and progressive neurological deficit state disc height was 4.03±0.53 mm, which were significantly different statisticaly (p<0.01. Symptoms of radiculopathy were seen in 11 patients and cauda equine syndrome in three patients. Modic changes grade 1 was found in five patients, grade 2 in eight patients,grade 3 in one patient, Pfirmman grade 2 in eleven patients and grade 3 in three patients. Thecal sac compression 1/3 compression was seen in four patients and 2/3 compression in ten patients. Conclusions: Neurosurgeon should raise concerns on the characteristic changes of intervertebral disc in magnetic resonance imaging examination to avoid further neural injury in lumbar herniated disc patients.

  6. Uso de mesa vertical como parâmetro para regulagens de turboatomizadores The use of a vertical patternator as parameter for adjustments of air assited sprayer

    Directory of Open Access Journals (Sweden)

    Renildo L. Mion

    2011-04-01

    Full Text Available O consumo excessivo de agrotóxicos na agricultura brasileira é preocupante, e um dos fatores que contribuem para este excesso é o uso incorreto dos equipamentos de aplicação, causando grandes problemas de contaminação ambiental. O sucesso de uma aplicação agrícola somente é efetivado quando se consegue atingir o alvo com a menor contaminação ambiental possível. O objetivo deste trabalho foi comparar o perfil da distribuição vertical de um turboatomizador com e sem fluxo de ar e o número de bicos utilizados nos ramais, utilizando-se de uma mesa vertical como parâmetro de avaliação. O conjunto utilizado foi um trator marca VALTRA, modelo BM-120 4x2 TODA, e um turboatomizador da marca Jacto, modelo ARBUS 400 GOLDEN, com pontas do tipo J5-2, pressão de 1378 kPa e velocidade do ar de 35 m s-1. O número de bicos não influenciou no perfil de distribuição volumétrico. O fluxo de ar influenciou no perfil de distribuição volumétrico tanto para o lado direito quanto para o lado esquerdo. Os maiores volumes ocorreram abaixo de 1,16 cm com o turboatomizador utilizando ou não o fluxo de ar, com 12 ou 6 pontas.Excessive consumption of pesticides in Brazilian agriculture is of concern, and one of the factors contributing to this surplus is the incorrect use of equipment for its applying, causing severe environmental contamination. The success of agricultural applications is effective only when it manages to hit the target with the lowest possible environmental contamination. The aim of this study was to compare the profile of the vertical distribution of an air assisted sprayer with and without air flow and the number of nozzles used in extensions, using a vertical patternator as the parameter. The set used was a Valtra tractor, model BM-120 4x2 TDA and one Jacto air assisted sprayer jet, model ARBUS 400 GOLDEN, with nozzle J5-2, and pressure of 1378 kPa, with air velocity of 35 m s-1 at the time of the test was conducted. The

  7. Curveballs in protoplanetary discs - the effect of the Magnus force on planet formation

    Science.gov (United States)

    Forbes, John C.

    2015-10-01

    Spinning planetesimals in a gaseous protoplanetary disc may experience a hydrodynamical force perpendicular to their relative velocities. We examine the effect this force has on the dynamics of these objects using analytical arguments based on a simple laminar disc model and numerical integrations of the equations of motion for individual grains. We focus in particular on metre-sized boulders traditionally expected to spiral in to the central star in as little as 100 years from 1 au We find that there are plausible scenarios in which this force extends the lifetime of these solids in the disc by a factor of several. More importantly the velocities induced by the Magnus force can prevent the formation of planetesimals via gravitational instability in the inner disc if the size of the dust particles is larger than of the order of 10 cm. We find that the fastest growing linear modes of the streaming instability may still grow despite the diffusive effect of the Magnus force, but it remains to be seen how the Magnus force will alter the non-linear evolution of these instabilities.

  8. Intradural disc herniation: how I do it.

    Science.gov (United States)

    Rodrigo, Víctor; Claramonte, Marta; Martín, Mónica; Calatayud, Juan B

    2018-03-12

    Intradural disc herniation is a rare phenomenon in spine surgery. Diagnosis is difficult despite current neuroradiologic imaging techniques. We present a case of a 59-year-old man with lumbar and radicular pain and a recurrent lumbar herniation. A laminectomy was performed after no clear disc herniation in the epidural space was found and an intradural mass was palpable. A durotomy showed an intradural disc fragment that was removed, followed by an arthrodesis. Only intraoperative findings lead to a definitive diagnosis for intradural herniation. A durotomy needs to be performed. In this case, an arthrodesis was necessary to avoid complications of segmental instability.

  9. Spectroscopic Parameters of Lumbar Intervertebral Disc Material

    Science.gov (United States)

    Terbetas, G.; Kozlovskaja, A.; Varanius, D.; Graziene, V.; Vaitkus, J.; Vaitkuviene, A.

    2009-06-01

    There are numerous methods of investigating intervertebral disc. Visualization methods are widely used in clinical practice. Histological, imunohistochemical and biochemical methods are more used in scientific research. We propose that a new spectroscopic investigation would be useful in determining intervertebral disc material, especially when no histological specimens are available. Purpose: to determine spectroscopic parameters of intervertebral disc material; to determine emission spectra common for all intervertebral discs; to create a background for further spectroscopic investigation where no histological specimen will be available. Material and Methods: 20 patients, 68 frozen sections of 20 μm thickness from operatively removed intervertebral disc hernia were excited by Nd:YAG microlaser STA-01-TH third harmonic 355 nm light throw 0, 1 mm fiber. Spectrophotometer OceanOptics USB2000 was used for spectra collection. Mathematical analysis of spectra was performed by ORIGIN multiple Gaussian peaks analysis. Results: In each specimen of disc hernia were found distinct maximal spectral peaks of 4 types supporting the histological evaluation of mixture content of the hernia. Fluorescence in the spectral regions 370-700 nm was detected in the disc hernias. The main spectral component was at 494 nm and the contribution of the components with the peak wavelength values at 388 nm, 412 nm and 435±5 nm were varying in the different groups of samples. In comparison to average spectrum of all cases, there are 4 groups of different spectral signatures in the region 400-500 nm in the patient groups, supporting a clinical data on different clinical features of the patients. Discussion and Conclusion: besides the classical open discectomy, new minimally invasive techniques of treating intervertebral disc emerge (PLDD). Intervertebral disc in these techniques is assessed by needle, no histological specimen is taken. Spectroscopic investigation via fiber optics through the

  10. Locally prepared antibiotic sensitivity discs: a substitute for imported ...

    African Journals Online (AJOL)

    Zones of inhibition were compared with those obtained from commercial antibiotic discs. Results obtained showed that discs prepared locally from antibiotic tablets, performed comparably with commercially obtained discs. There was no significant statistical difference between the two tested discs. We therefore recommend ...

  11. Inclination evolution of protoplanetary discs around eccentric binaries

    Science.gov (United States)

    Zanazzi, J. J.; Lai, Dong

    2018-01-01

    It is usually thought that viscous torque works to align a circumbinary disc with the binary's orbital plane. However, recent numerical simulations suggest that the disc may evolve to a configuration perpendicular to the binary orbit ('polar alignment) if the binary is eccentric and the initial disc-binary inclination is sufficiently large. We carry out a theoretical study on the long-term evolution of inclined discs around eccentric binaries, calculating the disc warp profile and dissipative torque acting on the disc. For discs with aspect ratio H/r larger than the viscosity parameter α, bending wave propagation effectively makes the disc precess as a quasi-rigid body, while viscosity acts on the disc warp and twist to drive secular evolution of the disc-binary inclination. We derive a simple analytic criterion (in terms of the binary eccentricity and initial disc orientation) for the disc to evolve towards polar alignment with the eccentric binary. When the disc has a non-negligible angular momentum compared to the binary, the final 'polar alignment' inclination angle is reduced from 90°. For typical protoplanetary disc parameters, the time-scale of the inclination evolution is shorter than the disc lifetime, suggesting that highly inclined discs and planets may exist orbiting eccentric binaries.

  12. Squeeze Film Behaviour in Rotating Porous Annular Discs ...

    African Journals Online (AJOL)

    The squeeze film behaviour between rotating annular discs, when the upper disc with a porous facing approached the parallel lower disc, was theoretically analysed. The lubricant was a magnetic fluid and the external magnetic field was oblique to the lower disc. Expressions were obtained for pressure, load capacity and ...

  13. Investigation of the coatings applied onto brake discs on disc-brake pad pair

    Directory of Open Access Journals (Sweden)

    I. Kiliçaslan

    2009-07-01

    Full Text Available While braking, according to the severity of it, thermal, metallurgical, constructive and tribological occurrences emerge on the brake disc-pad interface. In this study, NiCr was sprayed as bonding layer onto the discs, one ofwhich was coated with Al2O3-TiO2 by plasma spray and the other was coated with NiCr-Cr3C2 by High Velocity Oxygen Fuel (HVOF. In addition, the discs were tested with inertia dynamometer according to SAE’s J2522 testing procedure. The measurements showed that although the pads of the coated discs were exposed to higher braking temperatures, friction coefficient of the disc coated with NiCr- Cr3C2 was obtained 6 % higher compared to the original disc.

  14. Muon spin relaxation in random spin systems

    International Nuclear Information System (INIS)

    Toshimitsu Yamazaki

    1981-01-01

    The longitudinal relaxation function Gsub(z)(t) of the positive muon can reflect dynamical characters of local field in a unique way even when the correlation time is longer than the Larmor period of local field. This method has been applied to studies of spin dynamics in spin glass systems, revealing sharp but continuous temperature dependence of the correlation time. Its principle and applications are reviewed. (author)

  15. Is that lumbar disc symptomatic? Herniated lumbar disc associated with contralateral radiculopathy.

    Science.gov (United States)

    Abdul Jalil, Muhammad Fahmi; Lam, Miu Fei; Wang, Yi Yuen

    2014-05-07

    Herniated lumbar disc may be asymptomatic or associated with lower limb radiculopathy. Most spinal surgeons would offer surgery following a period of conservative measures if the radiological and clinical findings correlate. However, the existing dictum that lumbar radiculopathy should correlate with ipsilateral lumbar disc herniation may not be accurate as it can rarely present with contralateral sciatica. Literature regarding this phenomenon is scarce. Therefore, we report a patient with herniated lumbar disc presenting with predominantly contralateral motor weakness radiculopathy, which resolved after discectomy.

  16. Protoplanetary disc `isochrones' and the evolution of discs in the M˙-Md plane

    Science.gov (United States)

    Lodato, Giuseppe; Scardoni, Chiara E.; Manara, Carlo F.; Testi, Leonardo

    2017-12-01

    In this paper, we compare simple viscous diffusion models for the disc evolution with the results of recent surveys of the properties of young protoplanetary discs. We introduce the useful concept of 'disc isochrones' in the accretion rate-disc mass plane and explore a set of Monte Carlo realization of disc initial conditions. We find that such simple viscous models can provide a remarkable agreement with the available data in the Lupus star forming region, with the key requirement that the average viscous evolutionary time-scale of the discs is comparable to the cluster age. Our models produce naturally a correlation between mass accretion rate and disc mass that is shallower than linear, contrary to previous results and in agreement with observations. We also predict that a linear correlation, with a tighter scatter, should be found for more evolved disc populations. Finally, we find that such viscous models can reproduce the observations in the Lupus region only in the assumption that the efficiency of angular momentum transport is a growing function of radius, thus putting interesting constraints on the nature of the microscopic processes that lead to disc accretion.

  17. Transradicular lumbar disc herniation: An extreme variant of intraradicular disc herniation.

    Science.gov (United States)

    Kasliwal, Manish K; Shimer, Adam L

    2015-01-01

    Intradural or intraradicular lumbar disc herniation (IDH) is a relatively rare condition often diagnosed intraoperatively. We encountered an extreme variant of IDH - a transradicular herniation as the disc material extruded through the lumbar nerve root through a split essentially transecting the nerve root. While failure to recognize intradural and intraradicular disc herniation can lead to failed back surgery, the variant described in the present case could lead to iatrogenic injury and complication if not recognized. A unique case of transradicular lumbar disc herniation in a 25-year-old patient is presented with the depiction of intraoperative images supplementing the text.

  18. Treatment of lumbar disc herniation by percutaneous laser disc decompression (PLDD) and modified PLDD

    Science.gov (United States)

    Chi, Xiao fei; Li, Hong zhi; Wu, Ru zhou; Sui, Yun xian

    2005-07-01

    Objective: To study the micro-invasive operative method and to compare the effect of treatment of PLDD and modified PLDD for Lumbar Disc Herniation. Method: Vaporized part of the nucleus pulposus in single or multiple point after acupuncture into lumbar disc, to reach the purpose of the decompression of the lumbar disc. Result: Among the 19 cases of the regular PLDD group, the excellent and good rate was 63.2%, and among the 40 cases of the modified PLDD group, the excellent and good rate was 82.5%. Conclusion: The modified PLDD has good effect on the treatment for lumbar disc herniation.

  19. Transradicular lumbar disc herniation: An extreme variant of intraradicular disc herniation

    Directory of Open Access Journals (Sweden)

    Manish K Kasliwal

    2015-01-01

    Full Text Available Intradural or intraradicular lumbar disc herniation (IDH is a relatively rare condition often diagnosed intraoperatively. We encountered an extreme variant of IDH - a transradicular herniation as the disc material extruded through the lumbar nerve root through a split essentially transecting the nerve root. While failure to recognize intradural and intraradicular disc herniation can lead to failed back surgery, the variant described in the present case could lead to iatrogenic injury and complication if not recognized. A unique case of transradicular lumbar disc herniation in a 25-year-old patient is presented with the depiction of intraoperative images supplementing the text.

  20. Axial T2* mapping in intervertebral discs: a new technique for assessment of intervertebral disc degeneration

    Energy Technology Data Exchange (ETDEWEB)

    Hoppe, Sven; Quirbach, Sebastian; Krause, Fabian G.; Benneker, Lorin M. [Inselspital, Berne University Hospital, Department of Orthopaedic Surgery, Berne (Switzerland); Mamisch, Tallal C. [Inselspital, Berne University Hospital, Department of Radiology, Berne (Switzerland); Werlen, Stefan [Clinic Sonnenhof, Department of Radiology, Berne (Switzerland)

    2012-09-15

    To demonstrate the potential benefits of biochemical axial T2* mapping of intervertebral discs (IVDs) regarding the detection and grading of early stages of degenerative disc disease using 1.5-Tesla magnetic resonance imaging (MRI) in a clinical setting. Ninety-three patients suffering from lumbar spine problems were examined using standard MRI protocols including an axial T2* mapping protocol. All discs were classified morphologically and grouped as ''healthy'' or ''abnormal''. Differences between groups were analysed regarding to the specific T2* pattern at different regions of interest (ROIs). Healthy intervertebral discs revealed a distinct cross-sectional T2* value profile: T2* values were significantly lower in the annulus fibrosus compared with the nucleus pulposus (P = 0.01). In abnormal IVDs, T2* values were significantly lower, especially towards the centre of the disc representing the expected decreased water content of the nucleus (P = 0.01). In herniated discs, ROIs within the nucleus pulposus and ROIs covering the annulus fibrosus showed decreased T2* values. Axial T2* mapping is effective to detect early stages of degenerative disc disease. There is a potential benefit of axial T2* mapping as a diagnostic tool, allowing the quantitative assessment of intervertebral disc degeneration. circle Axial T2* mapping effective in detecting early degenerative disc disease. (orig.)

  1. Thermal analysis on motorcycle disc brake geometry

    Science.gov (United States)

    W. M. Zurin W., S.; Talib, R. J.; Ismail, N. I.

    2017-08-01

    Braking is a phase of slowing and stop the movement of motorcycle. During braking, the frictional heat was generated and the energy was ideally should be faster dissipated to surrounding to prevent the built up of the excessive temperature which may lead to brake fluid vaporization, thermoelastic deformation at the contact surface, material degradation and failure. In this paper, solid and ventilated type of motorcycle disc brake are being analyse using Computational Fluid Dynamic (CFD) software. The main focus of the analysis is the thermal behaviour during braking for solid and ventilated disc brake. A comparison between both geometries is being discussed to determine the better braking performance in term of temperature distribution. It is found that ventilated disc brake is having better braking performance in terms of heat transfer compare to solid disc.

  2. The susceptibilities in the spin-S Ising model

    International Nuclear Information System (INIS)

    Ainane, A.; Saber, M.

    1995-08-01

    The susceptibilities of the spin-S Ising model are evaluated using the effective field theory introduced by Tucker et al. for studying general spin-S Ising model. The susceptibilities are studied for all spin values from S = 1/2 to S = 5/2. (author). 12 refs, 4 figs

  3. Low back pain and degenerative disc disease

    OpenAIRE

    Jandrić Slavica; Antić Branislav

    2006-01-01

    Introduction. Various clinical conditions can cause low back pain, and in most cases it is of a degenerative origin. Degenerative disc disease is a common condition which affects young to middle-aged men and women equally. Changes in the mechanical properties of the disc lead to degenerative arthritis in the intervertebral joints, osteophytes, and narrowing the intervertebral foramen or the spinal canal. Pathophysiology. Degenerative cascade, described by Kirkaldy-Willis, is the widely accept...

  4. Myxomatous degeneration of the lumbar intervertebral disc.

    Science.gov (United States)

    Beatty, R A

    1985-08-01

    Sixteen patients were operated on for lumbar pain and pain radiating into the sciatic nerve distribution. In all 16, when the anulus fibrosus was incised, soft, gray disc material extruded under pressure like toothpaste being squeezed from a tube. This syndrome of myxomatous degeneration is a distinct entity, different from classical fibrotic disc degeneration or herniated nucleus pulposus. Surgical removal associated with partial facetectomy produced excellent results. The concept of incompetence of the anulus fibrosis is discussed.

  5. The lowest surface brightness disc galaxy known

    International Nuclear Information System (INIS)

    Davies, J.I.; Phillipps, S.; Disney, M.J.

    1988-01-01

    The discovery of a galaxy with a prominent bulge and a dominant extremely low surface brightness disc component is reported. The profile of this galaxy is very similar to the recently discovered giant low surface brightness galaxy Malin 1. The disc central surface brightness is found to be ∼ 26.4 Rμ, some 1.5 mag fainter than Malin 1 and thus by far the lowest yet observed. (author)

  6. Hygroviscoelasticity of the Human Intervertebral Disc.

    Science.gov (United States)

    1980-07-01

    occurs most frequently in the posterior portion of the disc and results often in pain - ful pressure on the spinal nerves. When high mechanical loads...nodes. This type of damage does not generally, per se, lead to pain symptoms, but because the phenomenon can change the overall stiffness of the disc...are fused with each other to form two bones, the sacrum and the coccyx . Figure 1 shows a lateral view of the vertebral column in the erect position

  7. Higher spin gauge theories

    CERN Document Server

    Henneaux, Marc; Vasiliev, Mikhail A

    2017-01-01

    Symmetries play a fundamental role in physics. Non-Abelian gauge symmetries are the symmetries behind theories for massless spin-1 particles, while the reparametrization symmetry is behind Einstein's gravity theory for massless spin-2 particles. In supersymmetric theories these particles can be connected also to massless fermionic particles. Does Nature stop at spin-2 or can there also be massless higher spin theories. In the past strong indications have been given that such theories do not exist. However, in recent times ways to evade those constraints have been found and higher spin gauge theories have been constructed. With the advent of the AdS/CFT duality correspondence even stronger indications have been given that higher spin gauge theories play an important role in fundamental physics. All these issues were discussed at an international workshop in Singapore in November 2015 where the leading scientists in the field participated. This volume presents an up-to-date, detailed overview of the theories i...

  8. Spin caloritronics in graphene

    Energy Technology Data Exchange (ETDEWEB)

    Ghosh, Angsula; Frota, H. O. [Department of Physics, Federal University of Amazonas, Av. Rodrigo Octavio 3000-Japiim, 69077-000 Manaus, AM (Brazil)

    2015-06-14

    Spin caloritronics, the combination of spintronics with thermoelectrics, exploiting both the intrinsic spin of the electron and its associated magnetic moment in addition to its fundamental electronic charge and temperature, is an emerging technology mainly in the development of low-power-consumption technology. In this work, we study the thermoelectric properties of a Rashba dot attached to two single layer/bilayer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current, which depends on the temperature and chemical potential. We demonstrate that the Rashba dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature, and also the Rashba term have been observed.

  9. Spin caloritronics in graphene

    Science.gov (United States)

    Frota, H. O.; Ghosh, Angsula

    2014-08-01

    Spin caloritronics, the combination of spintronics with thermoelectrics, based on spin and heat transport has attracted a great attention mainly in the development of low-power-consumption technology. In this work we study the thermoelectric properties of a quantum dot attached to two single layer graphene sheets as leads. The temperature difference on the two graphene leads induces a spin current which depends on the temperature and chemical potential. We demonstrate that the quantum dot behaves as a spin filter for selected values of the chemical potential and is able to filter electrons by their spin orientation. The spin thermopower has also been studied where the effects of the chemical potential, temperature and also the Coulomb repulsion due to the double occupancy of an energy level have been observed.

  10. CT findings of calcified herniated lumbar disc

    Energy Technology Data Exchange (ETDEWEB)

    Lim, Hyo Kun; Lee, Jun Hyung [Chang Dong Armed Forces Evacuation Hospital, Seoul (Korea, Republic of)

    1987-12-15

    Computed tomography (CT) of 10 calcified herniated lumber discs among 46 operated cases were analysed at the aspects of incidence, location, shape, etc. The results are as follows: 1. The incidence of calcification is 22% (10/46). 2. Among 10 cases, 3 cases are at the level of L4-5 disc space and 7 cases are at the level of L5-S1 disc space. 3. Central herniation (8 cases) are more common than posterolateral herniation (2 cases). 4. Linear or band-like calcifications in the periphery of herniated disc (annulus fibrosus type) are 6 cases and dense patchy calcification in the central portion of herniated disc (nucleus pulposus type) are 4 cases. 5. Two cases (50%) of 4 cases with nucleus pulposus type calcification were found to be ruptured at operation, but none of 6 annulus fibrous calcification types showed rupture. 6. Because more wide operation field and invasive exploration were required in calcified cases than non-calcified cases, it is suggested to evaluate the presence, location, and type of calcification in herniated disc in detail.

  11. Spin and Maximal Acceleration

    Directory of Open Access Journals (Sweden)

    Giorgio Papini

    2017-12-01

    Full Text Available We study the spin current tensor of a Dirac particle at accelerations close to the upper limit introduced by Caianiello. Continual interchange between particle spin and angular momentum is possible only when the acceleration is time-dependent. This represents a stringent limit on the effect that maximal acceleration may have on spin physics in astrophysical applications. We also investigate some dynamical consequences of maximal acceleration.

  12. Spin Hall effect devices

    Czech Academy of Sciences Publication Activity Database

    Jungwirth, Tomáš; Wunderlich, Joerg; Olejník, Kamil

    2012-01-01

    Roč. 11, č. 5 (2012), s. 382-390 ISSN 1476-1122 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 35.749, year: 2012

  13. Spin coating apparatus

    Science.gov (United States)

    Torczynski, John R.

    2000-01-01

    A spin coating apparatus requires less cleanroom air flow than prior spin coating apparatus to minimize cleanroom contamination. A shaped exhaust duct from the spin coater maintains process quality while requiring reduced cleanroom air flow. The exhaust duct can decrease in cross section as it extends from the wafer, minimizing eddy formation. The exhaust duct can conform to entrainment streamlines to minimize eddy formation and reduce interprocess contamination at minimal cleanroom air flow rates.

  14. A controllable spin prism

    International Nuclear Information System (INIS)

    Hakioglu, T

    2009-01-01

    Based on Khodas et al (2004 Phys. Rev. Lett. 92 086602), we propose a device acting like a controllable prism for an incident spin. The device is a large quantum well where Rashba and Dresselhaus spin-orbit interactions are present and controlled by the plunger gate potential, the electric field and the barrier height. A totally destructive interference can be manipulated externally between the Rashba and Dresselhaus couplings. The spin-dependent transmission/reflection amplitudes are calculated as the control parameters are changed. The device operates as a spin prism/converter/filter in different regimes and may stimulate research in promising directions in spintronics in analogy with linear optics.

  15. Quantum spin Hall phases

    International Nuclear Information System (INIS)

    Murakami, Shuichi

    2009-01-01

    We review our recent theoretical works on the quantum spin Hall effect. First we compare edge states in various 2D systems, and see whether they are robust or fragile against perturbations. Through the comparisons we see the robust nature of edge states in 2D quantum spin Hall phases. We see how it is protected by the Z 2 topological number, and reveal the nature of the Z 2 topological number by studying the phase transition between the quantum spin Hall and insulator phases. We also review our theoretical proposal of the ultrathin bismuth film as a candidate to the 2D quantum spin Hall system. (author)

  16. PREFACE: Spin Electronics

    Science.gov (United States)

    Dieny, B.; Sousa, R.; Prejbeanu, L.

    2007-04-01

    Conventional electronics has in the past ignored the spin on the electron, however things began to change in 1988 with the discovery of giant magnetoresistance in metallic thin film stacks which led to the development of a new research area, so called spin-electronics. In the last 10 years, spin-electronics has achieved a number of breakthroughs from the point of view of both basic science and application. Materials research has led to several major discoveries: very large tunnel magnetoresistance effects in tunnel junctions with crystalline barriers due to a new spin-filtering mechanism associated with the spin-dependent symmetry of the electron wave functions new magnetic tunnelling barriers leading to spin-dependent tunnelling barrier heights and acting as spin-filters magnetic semiconductors with increasingly high ordering temperature. New phenomena have been predicted and observed: the possibility of acting on the magnetization of a magnetic nanostructure with a spin-polarized current. This effect, due to a transfer of angular momentum between the spin polarized conduction electrons and the local magnetization, can be viewed as the reciprocal of giant or tunnel magnetoresistance. It can be used to switch the magnetization of a magnetic nanostructure or to generate steady magnetic excitations in the system. the possibility of generating and manipulating spin current without charge current by creating non-equilibrium local accumulation of spin up or spin down electrons. The range of applications of spin electronics materials and phenomena is expanding: the first devices based on giant magnetoresistance were the magnetoresistive read-heads for computer disk drives. These heads, introduced in 1998 with current-in plane spin-valves, have evolved towards low resistance tunnel magnetoresistice heads in 2005. Besides magnetic recording technology, these very sensitive magnetoresistive sensors are finding applications in other areas, in particular in biology. magnetic

  17. Local Noncollinear Spin Analysis.

    Science.gov (United States)

    Abate, Bayileyegn A; Joshi, Rajendra P; Peralta, Juan E

    2017-12-12

    In this work, we generalize the local spin analysis of Clark and Davidson [J. Chem. Phys. 2001 115 (16), 7382] for the partitioning of the expectation value of the molecular spin square operator, ⟨Ŝ 2 ⟩, into atomic contributions, ⟨Ŝ A ·Ŝ B ⟩, to the noncollinear spin case in the framework of density functional theory (DFT). We derive the working equations, and we show applications to the analysis of the noncollinear spin solutions of typical spin-frustrated systems and to the calculation of magnetic exchange couplings. In the former case, we employ the triangular H 3 He 3 test molecule and a Mn 3 complex to show that the local spin analysis provides additional information that complements the standard one-particle spin population analysis. For the calculation of magnetic exchange couplings, J AB , we employ the local spin partitioning to extract ⟨Ŝ A ·Ŝ B ⟩ as a function of the interatomic spin orientation given by the angle θ. This, combined with the dependence of the electronic energy with θ, provides a methodology to extract J AB from DFT calculations that, in contrast to conventional energy differences based methods, does not require the use of ad hoc S A and S B values.

  18. Spin glasses (II)

    International Nuclear Information System (INIS)

    Fischer, K.H.

    1985-01-01

    Experimental results of spin glass studies are reviewed and related to existing theories. Investigations of spin glasses are concentrated on atomic structure, metallurgical treatment, and high-temperature susceptibility of alloys, on magnetic properties at low temperature and near the freezing temperature, on anisotropy behaviour measured by ESR, NMR and torque, on specific heat, Moessbauer effect, neutron scattering and muon-spin depolarization experiments, ultrasound and transport properties. Some new theories of spin glasses are discussed which have been developed since Part I appeared

  19. Simple discs with flat roatation curves

    Science.gov (United States)

    Evans, N. W.; Collett, J. L.

    1993-09-01

    The aim of this paper is to understand why the squared axial ratio of the velocity ellipse, σphi_^2^/σ_R_^2^, of old disc stars in the Galaxy is less than 1/2. To this end, two infinitesimally thin steady-state axisymmetric discs with asymptotically flat circular velocity curves are presented. The first model - which we designate the Rybicki disc has surface density decaying inversely with radius. The second model is Freeman's exponential disc, which is immersed in the gravity field of the halo simulated by Mestel's potential. For both discs, we provide an infinite family of simple distribution functions, which form a sequence of increasing pressure support. In the Rybicki disc, the stellar streaming velocity increases outwards with radius, which typically causes σphi_^2^/σ_R_^2^ to be greater than 1/2. For our exponential disc distribution functions, the stellar streaming velocity declines outwards with radius, which typically causes σphi^2^/σ_R_^2^ to be less than 1/2. Our exponential disc distribution functions have the property that σ_R_^2^ decays only inversely with galactocentric radius R. If the diminution is faster, the ratio σphi_^2^/σ_R_^2^ rises above 1/2 at the Sun as the mean streaming velocity declines only in the inner disk. To investigate this, exponential discs with exponentially falling radial velocity dispersion are built. These are in conflict with the observations on the axial ratio, even allowing for a mismatch in the photometric and kinematic scalelengths. There are a number of possible resolutions of the contradiction: (1) the galactic disc is not in a steady state or is non-axisymmetric; (2) the circular velocity curve is locally declining; (3) the description of all stellar populations by a single distribution function is invalid; (4) the radial velocity dispersion does not drop off exponentially fast, but much more slowly; (5) the sampling of moving clusters and transient associations of stars creates a biased data set.

  20. Noise in tunneling spin current across coupled quantum spin chains

    OpenAIRE

    Aftergood, Joshua; Takei, So

    2017-01-01

    We theoretically study the spin current and its dc noise generated between two spin-1/2 spin chains weakly coupled at a single site in the presence of an over-population of spin excitations and a temperature elevation in one subsystem relative to the other, and compare the corresponding transport quantities across two weakly coupled magnetic insulators hosting magnons. In the spin chain scenario, we find that applying a temperature bias exclusively leads to a vanishing spin current and a conc...

  1. Star-disc interaction in galactic nuclei: formation of a central stellar disc

    Science.gov (United States)

    Panamarev, Taras; Shukirgaliyev, Bekdaulet; Meiron, Yohai; Berczik, Peter; Just, Andreas; Spurzem, Rainer; Omarov, Chingis; Vilkoviskij, Emmanuil

    2018-02-01

    We perform high resolution direct N-body simulations to study the effect of an accretion disc on stellar dynamics in an active galactic nucleus (AGN). We show that the interaction of the nuclear stellar cluster (NSC) with the gaseous disc (AD) leads to formation of a stellar disc in the central part of the NSC. The accretion of stars from the stellar disc onto the super-massive black hole is balanced by the capture of stars from the NSC into the stellar disc, yielding a stationary density profile. We derive the migration time through the AD to be 3% of the half-mass relaxation time of the NSC. The mass and size of the stellar disc are 0.7% of the mass and 5% of the influence radius of the super-massive black hole. An AD lifetime shorter than the migration time would result in a less massive nuclear stellar disc. The detection of such a stellar disc could point to past activity of the hosting galactic nucleus.

  2. Residual herniated disc material following hemilaminectomy in chondrodystrophic dogs with thoracolumbar intervertebral disc disease.

    Science.gov (United States)

    Roach, W J; Thomas, M; Weh, J M; Bleedorn, J; Wells, K

    2012-01-01

    To evaluate the presence of residual disc material within the vertebral canal following hemilaminectomy in chondrodystrophic dogs with thoracolumbar intervertebral disc disease. Forty dogs were treated by hemilaminectomy. Computed tomography was performed preoperatively and immediately postoperatively. The vertebral canal height, width, area, and herniated disc material area were measured. Maximum filling percentage (MFP), residual disc percentage (RDP), maximum residual filling percentage (MRFP), and residual filling percentage (RFP) were calculated. Clinical outcome was determined by telephone interviews. Residual disc material was present in 100% of the dogs. Mean MFP = 55.4% (range 25.9-82.3%; median 56.9%). Mean RDP = 50.3% (range 2.6-155.8%; median 47.9%). Mean MRFP = 30.8% (range 4.9-60%; median 30.1%). Mean RFP = 19.8% (range 4.8-45%; median 19.0%). All dogs were ambulatory with voluntary urination at the long-term follow-up (range: 88-735 days). Residual disc was present in all dogs following hemilaminectomy for intervertebral disc disease. Residual disc was not associated with failure to achieve functional recovery in these cases.

  3. A Simulation Model of Focus and Radial Servos in Compact Disc Players with Disc Surface Defects

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Stoustrup, Jakob; Andersen, Palle

    2004-01-01

    Compact Disc players have been on the market in more than two decades.As a consequence most of the control servo problems have been solved. A large remaining problem to solve is the handling of Compact Discs with severe surface defects like scratches and fingerprints. This paper introduces a method...

  4. Effect of spin rotation coupling on spin transport

    International Nuclear Information System (INIS)

    Chowdhury, Debashree; Basu, B.

    2013-01-01

    We have studied the spin rotation coupling (SRC) as an ingredient to explain different spin-related issues. This special kind of coupling can play the role of a Dresselhaus like coupling in certain conditions. Consequently, one can control the spin splitting, induced by the Dresselhaus like term, which is unusual in a semiconductor heterostructure. Within this framework, we also study the renormalization of the spin-dependent electric field and spin current due to the k → ⋅p → perturbation, by taking into account the interband mixing in the rotating system. In this paper we predict the enhancement of the spin-dependent electric field resulting from the renormalized spin rotation coupling. The renormalization factor of the spin electric field is different from that of the SRC or Zeeman coupling. The effect of renormalized SRC on spin current and Berry curvature is also studied. Interestingly, in the presence of this SRC-induced SOC it is possible to describe spin splitting as well as spin galvanic effect in semiconductors. -- Highlights: •Studied effect of spin rotation coupling on the spin electric field, spin current and Berry curvature. •In the k → ⋅p → framework we study the renormalization of spin electric field and spin current. •For an inertial system we have discussed the spin splitting. •Expression for the Berry phase in the inertial system is discussed. •The inertial spin galvanic effect is studied

  5. [Imaging study of lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation].

    Science.gov (United States)

    Yu, Qing-yang; Yang, Cun-rui; Yu, Lang-tao

    2009-04-01

    Using regional assignment to forked method to study lumbar intervertebral disc hemiation (bugle, hernia, prolapse) dependablity and reason of lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation. From March 2005 to October 2006, 120 patients of match condition from orthopaedics dept and rehabilitative dept of the Boai hospital of Longyan were studied. All patients were equally divided into two groups according to whether or not accompany with symptom of lumbar intervertebral disc herniation. There was not statistical difference in sex, age, course of disease, segment of intervertebral disc between two groups. Sixty patients of symptomatic lumbar intervertebral disc herniation were equally divided into three groups according to (bugle, hernia, prolapse) image on CT. Sixty patients of asymptomatic lumbar intervertebral disc herniation were equally divided into three groups according to (bugle, hernia, prolapse) image on CT. The age was 20-59 years old with an average of 38.5 years. Using regional assignment to give a mark respectively for every group. The sagittal diameter index (SI), anterior diastema of flaval ligaments, the width of superior outlet of latero-crypt, anteroposterior diameter of dura sac were respectively measured by sliding caliper. CT value and protrusible areas were respectively evaluated by computer tomography. Adopting mean value to measure three times. (1) There were not statistical difference in SI, CT value, hernia areas, anteroposterior diameter of dura sac between two groups (symptomatic lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation). There were statistical difference in the width of superior outlet of latero-crypt, anterior diastema of flaval ligaments between two groups (symptomatic lumbar intervertebral disc herniation and asymptomatic lumbar intervertebral disc herniation). (2) There were statistical difference in protrusible type,protrusible segment

  6. Cervical disc hernia operations through posterior laminoforaminotomy

    Directory of Open Access Journals (Sweden)

    Coskun Yolas

    2016-01-01

    Full Text Available Objective: The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. Materials and Methods: We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. Results: The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years. Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%. On control examinations, there was no finding of instability or cervical kyphosis. Conclusion: Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis.

  7. Only marginal alignment of disc galaxies

    Science.gov (United States)

    Andrae, René; Jahnke, Knud

    2011-12-01

    Testing theories of angular-momentum acquisition of rotationally supported disc galaxies is the key to understanding the formation of this type of galaxies. The tidal-torque theory aims to explain this acquisition process in a cosmological framework and predicts positive autocorrelations of angular-momentum orientation and spiral-arm handedness, i.e. alignment of disc galaxies, on short distance scales of 1 Mpc h-1. This disc alignment can also cause systematic effects in weak-lensing measurements. Previous observations claimed discovering these correlations but are overly optimistic in the reported level of statistical significance of the detections. Errors in redshift, ellipticity and morphological classifications were not taken into account, although they have a significant impact. We explain how to rigorously propagate all the important errors through the estimation process. Analysing disc galaxies in the Sloan Digital Sky Survey (SDSS) data base, we find that positive autocorrelations of spiral-arm handedness and angular-momentum orientations on distance scales of 1 Mpc h-1 are plausible but not statistically significant. Current data appear not good enough to constrain parameters of theory. This result agrees with a simple hypothesis test in the Local Group, where we also find no evidence for disc alignment. Moreover, we demonstrate that ellipticity estimates based on second moments are strongly biased by galactic bulges even for Scd galaxies, thereby corrupting correlation estimates and overestimating the impact of disc alignment on weak-lensing studies. Finally, we discuss the potential of future sky surveys. We argue that photometric redshifts have too large errors, i.e. PanSTARRS and LSST cannot be used. Conversely, the EUCLID project will not cover the relevant redshift regime. We also discuss the potentials and problems of front-edge classifications of galaxy discs in order to improve the autocorrelation estimates of angular-momentum orientation.

  8. Cervical disc hernia operations through posterior laminoforaminotomy.

    Science.gov (United States)

    Yolas, Coskun; Ozdemir, Nuriye Guzin; Okay, Hilmi Onder; Kanat, Ayhan; Senol, Mehmet; Atci, Ibrahim Burak; Yilmaz, Hakan; Coban, Mustafa Kemal; Yuksel, Mehmet Onur; Kahraman, Umit

    2016-01-01

    The most common used technique for posterolateral cervical disc herniations is anterior approach. However, posterior cervical laminotoforaminomy can provide excellent results in appropriately selected patients with foraminal stenosis in either soft disc prolapse or cervical spondylosis. The purpose of this study was to present the clinical outcomes following posterior laminoforaminotomy in patients with radiculopathy. We retrospectively evaluated 35 patients diagnosed with posterolateral cervical disc herniation and cervical spondylosis with foraminal stenosis causing radiculopathy operated by the posterior cervical keyhole laminoforaminotomy between the years 2010 and 2015. The file records and the radiographic images of the 35 patients were assessed retrospectively. The mean age was 46.4 years (range: 34-66 years). Of the patients, 19 were males and 16 were females. In all of the patients, the neurologic deficit observed was radiculopathy. The posterolaterally localized disc herniations and the osteophytic structures were on the left side in 18 cases and on the right in 17 cases. In 10 of the patients, the disc level was at C5-6, in 18 at C6-7, in 2 at C3-4, in 2 at C4-5, in 1 at C7-T1, in 1 patient at both C5-6 and C6-7, and in 1 at both C4-5 and C5-6. In 14 of these 35 patients, both osteophytic structures and protruded disc herniation were present. Intervertebral foramen stenosis was present in all of the patients with osteophytes. Postoperatively, in 31 patients the complaints were relieved completely and four patients had complaints of neck pain and paresthesia radiating to the arm (the success of operation was 88.5%). On control examinations, there was no finding of instability or cervical kyphosis. Posterior cervical laminoforaminotomy is an alternative appropriate choice in both cervical soft disc herniations and cervical stenosis.

  9. Spin labels. Applications in biology

    International Nuclear Information System (INIS)

    Frangopol, T.P.; Frangopol, M.; Ionescu, S.M.; Pop, I.V.; Benga, G.

    1980-11-01

    The main applications of spin labels in the study of biomembranes, enzymes, nucleic acids, in pharmacology, spin immunoassay are reviewed along with the fundamentals of the spin label method. 137 references. (author)

  10. Percutaneous laser disc decompression for lumbar disc hernia: indications based on Lasegue's Sign.

    Science.gov (United States)

    Iwatsuki, Koichi; Yoshimine, Toshiki; Awazu, Kunio

    2007-02-01

    The present study was conducted to establish reasonable indications of patient neurological manifestations for use of percutaneous laser disc decompression (PLDD). PLDD is a less invasive surgical procedure for lumbar disc hernia, whose indications have been described on the basis of radiographical findings. Sixty-five consecutive patients (45 men and 20 women) with lumbar disc hernia were treated with PLDD by applying a diode laser (wavelength 805 nm). A total of 450-1,205 joules (average, 805.5 joules) were delivered per disc. All patients suffered from radicular pain. They were divided based on the presence of Lasegue's sign. The post-procedure results at 1 week and 1 year were compared between the groups. PLDD was effective for patients with Lasegue's sign (80.0%), but ineffective for those without the sign. The present study suggests that Lasegue's sign in patients is an indication of PLDD for lumbar disc hernia.

  11. Spin Switching via Quantum Dot Spin Valves

    Science.gov (United States)

    Gergs, N. M.; Bender, S. A.; Duine, R. A.; Schuricht, D.

    2018-01-01

    We develop a theory for spin transport and magnetization dynamics in a quantum dot spin valve, i.e., two magnetic reservoirs coupled to a quantum dot. Our theory is able to take into account effects of strong correlations. We demonstrate that, as a result of these strong correlations, the dot gate voltage enables control over the current-induced torques on the magnets and, in particular, enables voltage-controlled magnetic switching. The electrical resistance of the structure can be used to read out the magnetic state. Our model may be realized by a number of experimental systems, including magnetic scanning-tunneling microscope tips and artificial quantum dot systems.

  12. Spin, mass, and symmetry

    Energy Technology Data Exchange (ETDEWEB)

    Peskin, M.E. [Stanford Univ., CA (United States)

    1994-12-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics.

  13. Physics lab in spin

    CERN Multimedia

    Hawkes, N

    1999-01-01

    RAL is fostering commerical exploitation of its research and facilities in two main ways : spin-out companies exploit work done at the lab, spin-in companies work on site taking advantage of the facilities and the expertise available (1/2 page).

  14. More spinoff from spin

    International Nuclear Information System (INIS)

    Masaike, Akira

    1993-01-01

    Despite playing a major role in today's Standard Model, spin - the intrinsic angular momentum carried by particles - is sometimes dismissed as an inessential complication. However several major spin questions with important implications for the Standard Model remain unanswered, and recent results and new technological developments made the 10th International Symposium on High Energy Spin Physics, held in Nagoya, Japan, in November, highly topical. The symposium covered a wide range of physics, reflecting the diversity of spin effects, however four main themes were - the spin content of the nucleon, tests of symmetries and physics beyond standard models, intermediate energy physics, and spin technologies. Opening the meeting, T. Kinoshita reviewed the status of measurements of the anomalous magnetic moment (g-2) of the electron and the muon. The forthcoming experiment at Brookhaven (September 1991, page 23) will probe beyond the energy ranges open to existing electronpositron colliders. For example muon substructure will be opened up to 5 TeV and Ws to 2 TeV. R.L. Jaffe classified quark-parton distributions in terms of their spin dependence, pointing out their leftright attributes, and emphasized the importance of measuring transverse spin distributions through lepton pair production

  15. Spin Hall noise

    NARCIS (Netherlands)

    Kamra, A.; Witek, F.P.; Meyer, S.; Huebl, H.; Geprägs, S.; Gross, R.; Bauer, G.E.W.; Goennenwein, S.T.B.

    2014-01-01

    We measure the low-frequency thermal fluctuations of pure spin current in a platinum film deposited on yttrium iron garnet via the inverse spin Hall effect (ISHE)-mediated voltage noise as a function of the angle ? between the magnetization and the transport direction. The results are consistent

  16. Antiferromagnetic spin Seebeck effect.

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Stephen M.; Zhang, Wei; KC, Amit; Borisov, Pavel; Pearson, John E.; Jiang, J. Samuel; Lederman, David; Hoffmann, Axel; Bhattacharya, Anand

    2016-03-03

    We report on the observation of the spin Seebeck effect in antiferromagnetic MnF2. A device scale on-chip heater is deposited on a bilayer of MnF2 (110) (30nm)/Pt (4 nm) grown by molecular beam epitaxy on a MgF2(110) substrate. Using Pt as a spin detector layer, it is possible to measure the thermally generated spin current from MnF2 through the inverse spin Hall effect. The low temperature (2–80 K) and high magnetic field (up to 140 kOe) regime is explored. A clear spin-flop transition corresponding to the sudden rotation of antiferromagnetic spins out of the easy axis is observed in the spin Seebeck signal when large magnetic fields (>9T) are applied parallel to the easy axis of the MnF2 thin film. When the magnetic field is applied perpendicular to the easy axis, the spin-flop transition is absent, as expected.

  17. Spin, mass, and symmetry

    International Nuclear Information System (INIS)

    Peskin, M.E.

    1994-01-01

    When the strong interactions were a mystery, spin seemed to be just a complication on top of an already puzzling set of phenomena. But now that particle physicists have understood the strong, weak, and electromagnetic interactions, to be gauge theories, with matter built of quarks and leptons, it is recognized that the special properties of spin 1/2 and spin 1 particles have taken central role in the understanding of Nature. The lectures in this summer school will be devoted to the use of spin in unravelling detailed questions about the fundamental interactions. Thus, why not begin by posing a deeper question: Why is there spin? More precisely, why do the basic pointlike constituents of Nature carry intrinsic nonzero quanta of angular momentum? Though the authos has found no definite answer to this question, the pursuit of an answer has led through a wonderful tangle of speculations on the deep structure of Nature. Is spin constructed or is it fundamental? Is it the requirement of symmetry? In the furthest flights taken, it seems that space-time itself is too restrictive a notion, and that this must be generalized in order to gain a full appreciation of spin. In any case, there is no doubt that spin must play a central role in unlocking the mysteries of fundamental physics

  18. Mismatch and misalignment: dark haloes and satellites of disc galaxies

    Science.gov (United States)

    Deason, A. J.; McCarthy, I. G.; Font, A. S.; Evans, N. W.; Frenk, C. S.; Belokurov, V.; Libeskind, N. I.; Crain, R. A.; Theuns, T.

    2011-08-01

    We study the phase-space distribution of satellite galaxies associated with late-type galaxies in the GIMIC suite of simulations. GIMIC consists of resimulations of five cosmologically representative regions from the Millennium Simulation, which have higher resolution and incorporate baryonic physics. Whilst the disc of the galaxy is well aligned with the inner regions (r˜ 0.1r200) of the dark matter halo, both in shape and angular momentum, there can be substantial misalignments at larger radii (r˜r200). Misalignments of >45° are seen in ˜30 per cent of our sample. We find that the satellite population aligns with the shape (and angular momentum) of the outer dark matter halo. However, the alignment with the galaxy is weak owing to the mismatch between the disc and dark matter halo. Roughly 20 per cent of the satellite systems with 10 bright galaxies within r200 exhibit a polar spatial alignment with respect to the galaxy - an orientation reminiscent of the classical satellites of the Milky Way. We find that a small fraction (˜10 per cent) of satellite systems show evidence for rotational support which we attribute to group infall. There is a bias towards satellites on prograde orbits relative to the spin of the dark matter halo (and to a lesser extent with the angular momentum of the disc). This preference towards co-rotation is stronger in the inner regions of the halo where the most massive satellites accreted at relatively early times are located. We attribute the anisotropic spatial distribution and angular momentum bias of the satellites at z= 0 to their directional accretion along the major axes of the dark matter halo. The satellite galaxies have been accreted relatively recently compared to the dark matter mass and have experienced less phase-mixing and relaxation - the memory of their accretion history can remain intact to z= 0. Understanding the phase-space distribution of the z= 0 satellite population is key for studies that estimate the host halo

  19. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden; Bjerrum Møller, Hans

    1975-01-01

    with increasing temperatures implies that the two-ion coupling is effectively isotropic above ∼ 150 K. We present arguments for concluding that, among the mechanisms which may introduce anisotropic two-ion couplings in the rare-earth metals, the modification of the indirect exchange interaction by the spin......The energies of spin waves propagating in the c direction of Tb have been studied by inelastic neutron scattering, as a function of a magnetic field applied along the easy and hard directions in the basal plane, and as a function of temperature. From a general spin Hamiltonian, consistent...... with the symmetry, we deduce the dispersion relation for the spin waves in a basal-plane ferromagnet. This phenomenological spin-wave theory accounts for the observed behavior of the magnon energies in Tb. The two q⃗-dependent Bogoliubov components of the magnon energies are derived from the experimental results...

  20. Spin Hall and spin swapping torques in diffusive ferromagnets

    KAUST Repository

    Pauyac, C. O.

    2017-12-08

    A complete set of the generalized drift-diffusion equations for a coupled charge and spin dynamics in ferromagnets in the presence of extrinsic spin-orbit coupling is derived from the quantum kinetic approach, covering major transport phenomena, such as the spin and anomalous Hall effects, spin swapping, spin precession and relaxation processes. We argue that the spin swapping effect in ferromagnets is enhanced due to spin polarization, while the overall spin texture induced by the interplay of spin-orbital and spin precessional effects displays a complex spatial dependence that can be exploited to generate torques and nucleate/propagate domain walls in centrosymmetric geometries without use of external polarizers, as opposed to the conventional understanding of spin-orbit mediated torques.

  1. DZ Chamaeleontis: a bona fide photoevaporating disc

    Science.gov (United States)

    Canovas, H.; Montesinos, B.; Schreiber, M. R.; Cieza, L. A.; Eiroa, C.; Meeus, G.; de Boer, J.; Ménard, F.; Wahhaj, Z.; Riviere-Marichalar, P.; Olofsson, J.; Garufi, A.; Rebollido, I.; van Holstein, R. G.; Caceres, C.; Hardy, A.; Villaver, E.

    2018-02-01

    Context. DZ Cha is a weak-lined T Tauri star (WTTS) surrounded by a bright protoplanetary disc with evidence of inner disc clearing. Its narrow Hα line and infrared spectral energy distribution suggest that DZ Cha may be a photoevaporating disc. Aims: We aim to analyse the DZ Cha star + disc system to identify the mechanism driving the evolution of this object. Methods: We have analysed three epochs of high resolution optical spectroscopy, photometry from the UV up to the sub-mm regime, infrared spectroscopy, and J-band imaging polarimetry observations of DZ Cha. Results: Combining our analysis with previous studies we find no signatures of accretion in the Hα line profile in nine epochs covering a time baseline of 20 yr. The optical spectra are dominated by chromospheric emission lines, but they also show emission from the forbidden lines [SII] 4068 and [OI] 6300Å that indicate a disc outflow. The polarized images reveal a dust depleted cavity of 7 au in radius and two spiral-like features, and we derive a disc dust mass limit of Mdust 80 MJup) companions are detected down to 0.̋07 ( 8 au, projected). Conclusions: The negligible accretion rate, small cavity, and forbidden line emission strongly suggests that DZ Cha is currently at the initial stages of disc clearing by photoevaporation. At this point the inner disc has drained and the inner wall of the truncated outer disc is directly exposed to the stellar radiation. We argue that other mechanisms like planet formation or binarity cannot explain the observed properties of DZ Cha. The scarcity of objects like this one is in line with the dispersal timescale (≲105 yr) predicted by this theory. DZ Cha is therefore an ideal target to study the initial stages of photoevaporation. Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 097.C-0536. Based on data obtained from the ESO Science Archive Facility under request number 250112.

  2. Spiral arms in thermally stratified protoplanetary discs

    Science.gov (United States)

    Juhász, Attila; Rosotti, Giovanni P.

    2018-02-01

    Spiral arms have been observed in nearly a dozen protoplanetary discs in near-infrared scattered light and recently also in the submillimetre continuum. While one of the most compelling explanations is that they are driven by planetary or stellar companions, in all but one cases such companions have not yet been detected and there is even ambiguity on whether the planet should be located inside or outside the spirals. Here, we use 3D hydrodynamic simulations to study the morphology of spiral density waves launched by embedded planets taking into account the vertical temperature gradient, a natural consequence of stellar irradiation. Our simulations show that the pitch angle of the spirals in thermally stratified discs is the lowest in the disc mid-plane and increases towards the disc surface. We combine the hydrodynamic simulations with 3D radiative transfer calculations to predict that the pitch angle of planetary spirals observed in the near-infrared is higher than in the submillimetre. We also find that in both cases the spirals converge towards the planet. This provides a new powerful observational method to determine if the perturbing planet is inside or outside the spirals, as well as map the thermal stratification of the disc.

  3. Active galactic nucleus outflows in galaxy discs

    Science.gov (United States)

    Hartwig, Tilman; Volonteri, Marta; Dashyan, Gohar

    2018-05-01

    Galactic outflows, driven by active galactic nuclei (AGNs), play a crucial role in galaxy formation and in the self-regulated growth of supermassive black holes (BHs). AGN feedback couples to and affects gas, rather than stars, and in many, if not most, gas-rich galaxies cold gas is rotationally supported and settles in a disc. We present a 2D analytical model for AGN-driven outflows in a gaseous disc and demonstrate the main improvements, compared to existing 1D solutions. We find significant differences for the outflow dynamics and wind efficiency. The outflow is energy-driven due to inefficient cooling up to a certain AGN luminosity (˜1043 erg s-1 in our fiducial model), above which the outflow remains momentum-driven in the disc up to galactic scales. We reproduce results of 3D simulations that gas is preferentially ejected perpendicular to the disc and find that the fraction of ejected interstellar medium is lower than in 1D models. The recovery time of gas in the disc, defined as the free-fall time from the radius to which the AGN pushes the ISM at most, is remarkably short, of the order 1 Myr. This indicates that AGN-driven winds cannot suppress BH growth for long. Without the inclusion of supernova feedback, we find a scaling of the BH mass with the halo velocity dispersion of MBH ∝ σ4.8.

  4. Footprint mismatch in lumbar total disc arthroplasty.

    Science.gov (United States)

    Gstoettner, Michaela; Michaela, Gstoettner; Heider, Denise; Denise, Heider; Liebensteiner, Michael; Bach, Christian Michael; Michael, Bach Christian

    2008-11-01

    Lumbar disc arthroplasty has become a popular modality for the treatment of degenerative disc disease. The dimensions of the implants are based on early published geometrical measurements of vertebrae; the majority of these were cadaver studies. The fit of the prosthesis in the intervertebral space is of utmost importance. An undersized implant may lead to subsidence, loosening and biomechanical failure due to an incorrect center of rotation. The aim of the present study was to measure the dimensions of lumbar vertebrae based on CT scans and assess the accuracy of match in currently available lumbar disc prostheses. A total of 240 endplates of 120 vertebrae were included in the study. The sagittal and mediolateral diameter of the upper and lower endplates were measured using a digital measuring system. For the levels L4/L5 and L5/S1, an inappropriate size match was noted in 98.8% (Prodisc L) and 97.6% (Charite) with regard to the anteroposterior diameter. Mismatch in the anterior mediolateral diameter was noted in 79.3% (Prodisc L) and 51.2% (Charite) while mismatch in the posterior mediolateral diameter was observed in 91.5% (Prodisc L) and 78% (Charite) of the endplates. Surgeons and manufacturers should be aware of the size mismatch of currently available lumbar disc prostheses, which may endanger the safety and efficacy of the procedure. Larger footprints of currently available total disc arthroplasties are required.

  5. Selection of Tubular and Endoscopic Transforaminal Disc Procedures Based on Disc Size, Location, and Characteristics

    Science.gov (United States)

    Palea, Ovidiu; Granville, Michelle

    2018-01-01

    The clinical effectiveness of percutaneous and transforaminal endoscopic discectomy procedures has been evaluated by the system used or compared to open laminectomy or micro-discectomy but are not evaluated based on the location and characteristics of the abnormal disc. This review proposes that outcomes are primarily related to disc size, biomechanics, location, and associated segmental fibrotic and bone changes as well as the surgeon's skill in using various systems rather than the specific system used. In these cases, the surgeon needs to decide if the goal of the procedure is simply internal decompression of an abnormal but contained herniated disc or release of the entrapped nerve root by a large contained disc, extruded and migrated disc fragment, or coexistent foraminal stenosis. Percutaneous and tubular transforaminal procedures are quite different, technically ranging from simple discectomy aspirating probes to larger endoscopic systems, providing the capability to remove large extruded free disc fragments, with or without foraminotomy. Recently, the ability to perform interbody fusion has been added to the range of procedures able to be performed endoscopically. At the same time, biologic solutions to disc degeneration are rapidly evolving and may have a place in combination with these procedures. This article reviews the interrelationship between clinical signs and symptoms, radiologic findings, and the biochemistry and biomechanics of the affected disc segment. Understanding the role played by all these factors enables the surgeon to evaluate both the disc and surrounding bone structures pre-operatively to determine if the clinical signs and symptoms are related to enlargement and displacement of a contained disc or compression or impingement of the nerve root. Based on this, the surgeon can choose different surgical systems, allowing simple decompression of a contained disc, possibly adding biologics, with a 'small' system, while a large

  6. Jamming Transition: Heptagons, Pentagons, and Discs

    Directory of Open Access Journals (Sweden)

    Xu Yuanyuan

    2017-01-01

    Full Text Available The jamming behavior of a system composed of discs has been well documented. However, it remains unclear how a granular system consisting of non-spherical particles transitions between unjammed and jammed states. Here, we present compression experiments to study the jamming transition of 2D granular materials composed of photoelastic heptagonal particles and compare these results to data for discs and pentagons. We determine the critical packing fraction of heptagons and make a comparison to discs and pentagons. In the experiment, we subject 618 heptagonal particles to cyclic compression. We track the motion (inlcuding rotations of the particles, and we measure forces on particles by photoelasticity. We observe a power law relationship between the average contact number (Z and the pressure (P. Furthermore, we classify the type of contacts by the relative orientation of pairs of contacting particles (creating point-to-face and face-to-face contacts, and we explore the evolution of the contacts during jamming.

  7. On the formation of exponential discs

    International Nuclear Information System (INIS)

    Yoshii, Yuzuru; Sommer-Larsen, Jesper

    1989-01-01

    Spiral galaxy discs are characterized by approximately exponential surface luminosity profiles. In this paper the evolutionary equations for a star-forming, viscous disc are solved analytically or semi-analytically. It is shown that approximately exponential stellar surface density profiles result if the viscous time-scale t ν is comparable to the star-formation time scale t * everywhere in the disc. The analytical solutions are used to illuminate further on the issue of why the above mechanism leads to resulting exponential stellar profiles under certain conditions. The sensitivity of the solution to variations of various parameters are investigated and show that the initial gas surface density distribution has to be fairly regular in order that final exponential stellar surface density profiles result. (author)

  8. OPTIC DISC MELANOCYTOMA: A CASE REPORT

    Directory of Open Access Journals (Sweden)

    Sahiba Bedi

    2016-08-01

    Full Text Available Melanocytoma of the optic disc is a rare ophthalmic tumour that arises from melanocytes and is a variant of the melanocytic nevus. It occurs on the optic disc and often extends into the peripapillary retina and choroid. It appears as a dark brown or black lesion, typically small and is almost always unilateral. Although traditionally believed to be a relatively stationary lesion, it is now known to exhibit minor enlargement in 10–15% of cases and can cause minor visual loss by a variety of mechanisms. 1-2% cases can transform to malignant melanoma. We present a case report of a 65-year-old female whose dilated fundus examination of the right eye revealed a circular, pigmented and elevated lesion about 1.5 mm in size covering almost whole of the optic nerve head except for the superior rim, suggestive of optic disc melanocytoma.

  9. Resonant Tunneling Spin Pump

    Science.gov (United States)

    Ting, David Z.

    2007-01-01

    The resonant tunneling spin pump is a proposed semiconductor device that would generate spin-polarized electron currents. The resonant tunneling spin pump would be a purely electrical device in the sense that it would not contain any magnetic material and would not rely on an applied magnetic field. Also, unlike prior sources of spin-polarized electron currents, the proposed device would not depend on a source of circularly polarized light. The proposed semiconductor electron-spin filters would exploit the Rashba effect, which can induce energy splitting in what would otherwise be degenerate quantum states, caused by a spin-orbit interaction in conjunction with a structural-inversion asymmetry in the presence of interfacial electric fields in a semiconductor heterostructure. The magnitude of the energy split is proportional to the electron wave number. Theoretical studies have suggested the possibility of devices in which electron energy states would be split by the Rashba effect and spin-polarized currents would be extracted by resonant quantum-mechanical tunneling.

  10. Nuclear spins in nanostructures

    International Nuclear Information System (INIS)

    Coish, W.A.; Baugh, J.

    2009-01-01

    We review recent theoretical and experimental advances toward understanding the effects of nuclear spins in confined nanostructures. These systems, which include quantum dots, defect centers, and molecular magnets, are particularly interesting for their importance in quantum information processing devices, which aim to coherently manipulate single electron spins with high precision. On one hand, interactions between confined electron spins and a nuclear-spin environment provide a decoherence source for the electron, and on the other, a strong effective magnetic field that can be used to execute local coherent rotations. A great deal of effort has been directed toward understanding the details of the relevant decoherence processes and to find new methods to manipulate the coupled electron-nuclear system. A sequence of spectacular new results have provided understanding of spin-bath decoherence, nuclear spin diffusion, and preparation of the nuclear state through dynamic polarization and more general manipulation of the nuclear-spin density matrix through ''state narrowing.'' These results demonstrate the richness of this physical system and promise many new mysteries for the future. (Abstract Copyright [2009], Wiley Periodicals, Inc.)

  11. Spin drift and spin diffusion currents in semiconductors

    Energy Technology Data Exchange (ETDEWEB)

    Idrish Miah, M [Nanoscale Science and Technology Centre and School of Biomolecular and Physical Sciences, Griffith University, Nathan, Brisbane, QLD 4111 (Australia)], E-mail: m.miah@griffith.edu.au

    2008-09-15

    On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

  12. Spin drift and spin diffusion currents in semiconductors

    Directory of Open Access Journals (Sweden)

    M Idrish Miah

    2008-01-01

    Full Text Available On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

  13. Spin drift and spin diffusion currents in semiconductors

    International Nuclear Information System (INIS)

    Idrish Miah, M

    2008-01-01

    On the basis of a spin drift-diffusion model, we show how the spin current is composed and find that spin drift and spin diffusion contribute additively to the spin current, where the spin diffusion current decreases with electric field while the spin drift current increases, demonstrating that the extension of the spin diffusion length by a strong field does not result in a significant increase in spin current in semiconductors owing to the competing effect of the electric field on diffusion. We also find that there is a spin drift-diffusion crossover field for a process in which the drift and diffusion contribute equally to the spin current, which suggests a possible method of identifying whether the process for a given electric field is in the spin drift or spin diffusion regime. Spin drift-diffusion crossover fields for GaAs are calculated and are found to be quite small. We derive the relations between intrinsic spin diffusion length and the spin drift-diffusion crossover field of a semiconductor for different electron statistical regimes. The findings resulting from this investigation might be important for semiconductor spintronics.

  14. Forming spectroscopic massive protobinaries by disc fragmentation

    Science.gov (United States)

    Meyer, D. M.-A.; Kuiper, R.; Kley, W.; Johnston, K. G.; Vorobyov, E.

    2018-01-01

    The surroundings of massive protostars constitute an accretion disc which has numerically been shown to be subject to fragmentation and responsible for luminous accretion-driven outbursts. Moreover, it is suspected to produce close binary companions which will later strongly influence the star's future evolution in the Hertzsprung-Russel diagram. We present three-dimensional gravitation-radiation-hydrodynamic numerical simulations of 100 M⊙ pre-stellar cores. We find that accretion discs of young massive stars violently fragment without preventing the (highly variable) accretion of gaseous clumps on to the protostars. While acquiring the characteristics of a nascent low-mass companion, some disc fragments migrate on to the central massive protostar with dynamical properties showing that its final Keplerian orbit is close enough to constitute a close massive protobinary system, having a young high- and a low-mass components. We conclude on the viability of the disc fragmentation channel for the formation of such short-period binaries, and that both processes - close massive binary formation and accretion bursts - may happen at the same time. FU-Orionis-type bursts, such as observed in the young high-mass star S255IR-NIRS3, may not only indicate ongoing disc fragmentation, but also be considered as a tracer for the formation of close massive binaries - progenitors of the subsequent massive spectroscopic binaries - once the high-mass component of the system will enter the main-sequence phase of its evolution. Finally, we investigate the Atacama Large (sub-)Millimeter Array observability of the disc fragments.

  15. Periodic inspection of sprayers: diagnostic to the northern of Paraná Inspeção periódica de pulverizadores: diagnóstico para a região norte do Paraná

    Directory of Open Access Journals (Sweden)

    Marco A. Gandolfo

    2013-04-01

    Full Text Available To optimize the use of pesticides, several countries have carried out periodic inspections in agricultural sprayers. In Brazil, knowing the conditions of this machinery canguide researches and investments in guidelines for its use and maintenance. The objective of this study was to verify the state of sprayer maintenance used in the North of the state of Paraná, in Brazil. Several sprayer items were evaluated, such as: presence, status and scale of the manometer, status of the hose, status of the anti-drip component, presence of leaks, status of the bar, status of the filters, state of the spraying nozzles and errors in the targeted flow rate. Machines were named as approved when there was no failure in any item evaluated. The factor that caused the biggest level of reprove among the machines was incorrect scale of manometers, which reproved 84.55% of the machines evaluated. Other outstanding factor was the incorrect flow rate in 75.5% of the tested machines. Only one unit was approved from the total of 110 evaluated sprayers.Para a otimização no uso de agroquímicos, vários países têm realizado inspeções periódicas em pulverizadores agrícolas. No Brasil, o conhecimento do estado destas máquinas pode nortear pesquisas e investimentos em orientação de uso e de manutenção das mesmas. O objetivo deste trabalho foi verificar o estado de manutenção de pulverizadores em uso para a região norte do Estado do Paraná. Foram avaliados itens como: presença, estado e escala do manômetro, estado das mangueiras, estado dos antigotejadores, presença de vazamentos, estado da barra, estado dos filtros, estado das pontas de pulverização e erros na taxa de aplicação. As máquinas foram caracterizadas como aprovadas quando não havia falha em nenhum item avaliado. O fator que ocasionou o maior índice de reprova entre as máquinas foi a escala incorreta do manômetro, que reprovou 84,55% das máquinas avaliadas. Outro fator de destaque foi

  16. Higher spins and holography

    Science.gov (United States)

    Kraus, Per; Ross, Simon F.

    2013-05-01

    The principles of quantum mechanics and relativity impose rigid constraints on theories of massless particles with nonzero spin. Indeed, Yang-Mills theory and General Relativity are the unique solution in the case of spin-1 and spin-2. In asymptotically flat spacetime, there are fundamental obstacles to formulating fully consistent interacting theories of particles of spin greater than 2. However, indications are that such theories are just barely possible in asymptotically anti-de Sitter or de Sitter spacetimes, where the non-existence of an S-matrix provides an escape from the theorems restricting theories in Minkowski spacetime. These higher spin gravity theories are therefore of great intrinsic interest, since they, along with supergravity, provide the only known field theories generalizing the local invariance principles of Yang-Mills theory and General Relativity. While work on higher spin gravity goes back several decades, the subject has gained broader appeal in recent years due to its appearance in the AdS/CFT correspondence. In three and four spacetime dimensions, there exist duality proposals linking higher spin gravity theories to specific conformal field theories living in two and three dimensions respectively. The enlarged symmetry algebra of the conformal field theories renders them exactly soluble, which makes them excellent laboratories for understanding in detail the holographic mechanism behind AdS/CFT duality. Steady progress is also being made on better understanding the space of possible higher spin gravity theories and their physical content. This work includes classifying the possible field multiplets and their interactions, constructing exact solutions of the nonlinear field equations, and relating higher spin theories to string theory. A full understanding of these theories will involve coming to grips with the novel symmetry principles that enlarge those of General Relativity and Yang-Mills theory, and one can hope that this will provide

  17. 'Hard discs' associated with lumbar disc herniation: CT analysis

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Il Kwon; Bang, Dae Hong; Yim, Jung Ik; Lee, Jae Mun; Bahk, Yong Whee [Catholic University Medical College, Seoul (Korea, Republic of)

    1989-02-15

    Thirty cases showing hard discs were collected from 206 consecutive cases of posterior disk herniation during the past one and a half years period. According to the shape of hard disk and the presence of marginal bone defect (MBD) of vertebral end plate, 30 cases could be categorized into 4 distinct groups. They were small hard disc with focal MBD (group 1), large hard disc with broad based MBD (group 2), hard disc separated from vertebral body without MBD (group 3) and hard disc fused with vertebral body without MBD (group 4). There were 14 patients in group 1. In all but one case, the hard disc and MBDs were located at the paramedial aspect of the posterior margin of the end plate. Ten (76.9%) of these had Schmorl's nodes and these were considered to represented an avulsion from the weakened bone margin as the disk herniated acutely. The posterior longitudinal ligament seemed to have prevented detachment of the bony fragment. Group 2 included 2 patients and CT findings as well as plain X-ray features were identical to a limbus vertebra. This was considered to represent passive displacement of bony fragment by the intravertebral herniation of the disk. Nine patients belonged to group 3 and represent dystrophic calcifications of herniated disk. Group 4 included 5 patients and was disclosed as a simple osteophyte. From our study, it was concluded; (1) that the hard disc seen in lumbar CT scan was probably the results of the detachment of a bone fragment from the vertebral end plate which has an underlying weak area due to the herniated disc as well as a calcification or osteophyte formation and (2) specific terms (avulsed fragment, limbus vertebra, calcification or spur formation) is more preferable to use than hard disc which is inaccurate.

  18. Expression of heparanase isoforms in intervertebral discs classified according to Pfirrmann grading system for disc degeneration.

    Science.gov (United States)

    Rodrigues, Luciano Miller Reis; Oliveira, Lilian Zerbinatti de; Pinhal, Maria Aparecida da Silva

    2013-06-01

    This is a quantitative study of heparanase isoforms expression in degenerative and nondegenerative intervertebral discs (IVDs). To quantify the expression of both heparanase isoforms (HPSE1 and HPSE2) in IVD tissues as classified by different degeneration grades using the Pfirrmann grading system, and to correlate the expression with the loss of extracellular matrix molecules observed in patients with the disease. The loss of proteoglycans as observed in IVD degeneration may occur due to the enhanced expression of matrix degrading enzymes, such as heparanase. However, the heparanase function in IVD degeneration remains unclear. This study comprised 53 surgical samples of degenerative discs obtained from patients with lumbar disc degeneration and 12 control samples collected from healthy individuals without any degenerative lumbar disc alterations who had accidental spine fractures.All patients underwent magnetic resonance imaging based on the Pfirrmann grading system for disc degeneration. Only the specimens that were classified according to magnetic resonance imaging evaluations as Pfirrmann grades I, II, III, and IV were analyzed.The tissue sections of the disc samples were subject to immunohistochemical staining with antibodies against the heparanase isoforms and to quantitative real time PCR to amplify heparanase isoforms cDNA. Protein and mRNA expressions were quantified. Analysis of variance and Student t test were used to compare the means of the study populations. The data demonstrated a gradual increase in both the heparanase isoform protein expression and disc degeneration progression. Besides, mRNA expression of both heparanase isoforms were significantly higher in degenerative than nondegenerative IVDs. The overexpression of HPSE1 and HPSE2 in the intervertebral degenerated discs suggests a role for these factors in mediating extracellular matrix remodeling in degenerative discs during disease development.

  19. Spin transfer torque with spin diffusion in magnetic tunnel junctions

    KAUST Repository

    Manchon, Aurelien

    2012-08-09

    Spin transport in magnetic tunnel junctions in the presence of spin diffusion is considered theoretically. Combining ballistic tunneling across the barrier and diffusive transport in the electrodes, we solve the spin dynamics equation in the metallic layers. We show that spin diffusion mixes the transverse spin current components and dramatically modifies the bias dependence of the effective spin transfer torque. This leads to a significant linear bias dependence of the out-of-plane torque, as well as a nonconventional thickness dependence of both spin torque components.

  20. Electron spin and nuclear spin manipulation in semiconductor nanosystems

    International Nuclear Information System (INIS)

    Hirayama, Yoshiro; Yusa, Go; Sasaki, Satoshi

    2006-01-01

    Manipulations of electron spin and nuclear spin have been studied in AlGaAs/GaAs semiconductor nanosystems. Non-local manipulation of electron spins has been realized by using the correlation effect between localized and mobile electron spins in a quantum dot- quantum wire coupled system. Interaction between electron and nuclear spins was exploited to achieve a coherent control of nuclear spins in a semiconductor point contact device. Using this device, we have demonstrated a fully coherent manipulation of any two states among the four spin levels of Ga and As nuclei. (copyright 2006 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  1. Spins in chemistry

    CERN Document Server

    McWeeny, Roy

    2004-01-01

    Originally delivered as a series of lectures, this volume systematically traces the evolution of the ""spin"" concept from its role in quantum mechanics to its assimilation into the field of chemistry. Author Roy McWeeny presents an in-depth illustration of the deductive methods of quantum theory and their application to spins in chemistry, following the path from the earliest concepts to the sophisticated physical methods employed in the investigation of molecular structure and properties. Starting with the origin and development of the spin concept, the text advances to an examination of sp

  2. Frustrated spin systems

    CERN Document Server

    2013-01-01

    This book covers all principal aspects of currently investigated frustrated systems, from exactly solved frustrated models to real experimental frustrated systems, going through renormalization group treatment, Monte Carlo investigation of frustrated classical Ising and vector spin models, low-dimensional systems, spin ice and quantum spin glass. The reader can - within a single book - obtain a global view of the current research development in the field of frustrated systems.This new edition is updated with recent theoretical, numerical and experimental developments in the field of frustrated

  3. Spin Hall effect transistor

    Czech Academy of Sciences Publication Activity Database

    Wunderlich, Joerg; Park, B.G.; Irvine, A.C.; Zarbo, Liviu; Rozkotová, E.; Němec, P.; Novák, Vít; Sinova, Jairo; Jungwirth, Tomáš

    2010-01-01

    Roč. 330, č. 6012 (2010), s. 1801-1804 ISSN 0036-8075 R&D Projects: GA AV ČR KAN400100652; GA MŠk LC510 EU Projects: European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : spin Hall effect * spintronics * spin transistor Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 31.364, year: 2010

  4. Spin tracking in RHIC

    Energy Technology Data Exchange (ETDEWEB)

    Luccio, A.U. [Brookhaven National Lab., Upton, NY (United States); Katayama, T. [Univ. of Tokyo (Japan); Wu, H. [Riken Inst., Tokyo (Japan)

    1997-07-01

    In the acceleration of polarized protons in RHIC many spin depolarizing resonances are encountered. Helical Siberian snakes will be used to overcome depolarizing effects. The behavior of polarization can be studied by numerical tracking in a model accelerator. That allows one to check the strength of the resonances, to study the effect of snakes, to find safe lattice tune regions, and finally to study the operation of special devices like spin flippers. In this paper the authors describe numerical spin tracking. Results show that, for the design corrected distorted orbit and the design beam emittance, the polarization of the beam will be preserved in the whole range of proton energies in RHIC.

  5. SPINning parallel systems software

    International Nuclear Information System (INIS)

    Matlin, O.S.; Lusk, E.; McCune, W.

    2002-01-01

    We describe our experiences in using Spin to verify parts of the Multi Purpose Daemon (MPD) parallel process management system. MPD is a distributed collection of processes connected by Unix network sockets. MPD is dynamic processes and connections among them are created and destroyed as MPD is initialized, runs user processes, recovers from faults, and terminates. This dynamic nature is easily expressible in the Spin/Promela framework but poses performance and scalability challenges. We present here the results of expressing some of the parallel algorithms of MPD and executing both simulation and verification runs with Spin

  6. Natural course of lumber disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Tokioka, Takamitsu; Shimada, Kimio; Tanaka, Yuzo; Oshige, Toshihisa; Miyakoshi, Koichi [Okayama Rosai Hospital (Japan)

    1998-09-01

    Thirty-two cases of lumbar disc herniation were sequentially followed by MR imagings in order to ascertain its natural course. Herniation consisted of protrusion in 6 cases, extrusion in 13 cases, and sequestration in 13 cases. We analysed the durations until the herniation regressed more than 50% of its A-P diameter. The mean duration was 8.2 months for extrusion, and 5.3 months for sequestration. Only 2 cases of protrusion regressed within 12 months. Huge disc herniations with central protrusion in particular showed slight spontaneous regression. (author)

  7. Cells and Biomaterials for Intervertebral Disc Regeneration

    CERN Document Server

    Grad, Sibylle

    2010-01-01

    Disorders related to the intervertebral disc (IVD) are common causes of morbidity and of severe life quality deterioration. IVD degeneration, although in many cases asymptomatic, is often the origin of painful neck and back diseases. In Western societies IVD related pain and disability account for enormous health care costs as a result of work absenteeism and thus lost production, disability benefits, medical and insurance expenses. Although only a small percentage of patients with disc disorders finally will undergo surgery, spinal surgery has been one of the fastest growing disciplines in th

  8. Imaging characteristics of noncontained migrating disc fragment and cyst

    International Nuclear Information System (INIS)

    Eerens, I.; Demaerel, P.; Haven, F.; Wilms, G.; Loon, J. van; Calenbergh, F. van

    2001-01-01

    The purpose of this article is to review less common presentations of degenerative disc disease on MR imaging. The images of eight patients were retrospectively analyzed. Six of them had transligamentous (or noncontained) disc herniations, the fragments of which were located in the posterior epidural space in three of them. One patient had a transdural disc fragment and one patient had a disc cyst. The cyst was located in the ventrolateral epidural space. On T2-weighted images, the migrated disc fragment returned a higher signal than the disc of origin in 6 of 7 patients. The disc cyst returned a signal similar to that of cerebrospinal fluid. The MR appearances of disc fragments can be puzzling, particularly if they are located in the posterior epidural space. It is important to recognize the abnormalities in order to differentiate them from less common lesions such as hematoma, abscess and neurinoma. (orig.)

  9. Imaging characteristics of noncontained migrating disc fragment and cyst

    Energy Technology Data Exchange (ETDEWEB)

    Eerens, I.; Demaerel, P.; Haven, F.; Wilms, G. [Dept. of Radiology, University Hospitals, Leuven (Belgium); Loon, J. van; Calenbergh, F. van [Dept. of Neurosurgery, University Hospitals, Leuven (Belgium)

    2001-05-01

    The purpose of this article is to review less common presentations of degenerative disc disease on MR imaging. The images of eight patients were retrospectively analyzed. Six of them had transligamentous (or noncontained) disc herniations, the fragments of which were located in the posterior epidural space in three of them. One patient had a transdural disc fragment and one patient had a disc cyst. The cyst was located in the ventrolateral epidural space. On T2-weighted images, the migrated disc fragment returned a higher signal than the disc of origin in 6 of 7 patients. The disc cyst returned a signal similar to that of cerebrospinal fluid. The MR appearances of disc fragments can be puzzling, particularly if they are located in the posterior epidural space. It is important to recognize the abnormalities in order to differentiate them from less common lesions such as hematoma, abscess and neurinoma. (orig.)

  10. Relationship of condylar position to disc position and morphology

    Energy Technology Data Exchange (ETDEWEB)

    Incesu, L.; Taskaya-Yilmaz, N. E-mail: nergizy@omu.edu.tr; Oeguetcen-Toller, M.; Uzun, E

    2004-09-01

    Introduction/objective: The purpose of this study was to assess whether condylar position, as depicted by magnetic resonance imaging, was an indicator of disc morphology and position. Methods and material: One hundred and twenty two TMJs of 61 patients with temporomandibular joint disorder were examined. Condylar position, disc deformity and degree of anterior disc displacement were evaluated by using magnetic resonance imaging. Results and discussion: Posterior condyle position was found to be the main feature of temporomandibular joints with slight and moderate anterior disc displacement. No statistical significance was found between the condylar position, and reducing and nonreducing disc positions. On the other hand, superior disc position was found to be statistically significant for centric condylar position. Conclusion: It was concluded that posterior condyle position could indicate anterior disc displacement whereas there was no relation between the position of condyle and the disc deformity.

  11. Angiogenesis in the degeneration of the lumbar intervertebral disc

    OpenAIRE

    David, Gh; Ciurea, AV; Iencean, SM; Mohan, A

    2010-01-01

    The goal of the study is to show the histological and biochemical changes that indicate the angiogenesis of the intervertebral disc in lumbar intervertebral disc hernia and the existence of epidemiological correlations between these changes and the risk factors of lumbar intervertebral disc hernia, as well as the patient's quality of life (QOL). We have studied 50 patients aged between 18 and 73 years old, who have undergone lumbar intervertebral disc hernia surgery, making fibroblast growth ...

  12. Spin squeezing and quantum correlations

    Indian Academy of Sciences (India)

    2 states. A coherent spin-s state. (CSS) θ φ can then be thought of as having no quantum correlations as the constituent. 2s elementary spins point in the same direction ˆn(θ φ) which is the mean spin direction. 2. State classification and squeezing. In order to discuss squeezing, we begin with the squeezing condition itself.

  13. Geometry of spin coherent states

    Science.gov (United States)

    Chryssomalakos, C.; Guzmán-González, E.; Serrano-Ensástiga, E.

    2018-04-01

    Spin states of maximal projection along some direction in space are called (spin) coherent, and are, in many respects, the ‘most classical’ available. For any spin s, the spin coherent states form a 2-sphere in the projective Hilbert space \

  14. Spin Hall effect and spin swapping in diffusive superconductors

    Science.gov (United States)

    Espedal, Camilla; Lange, Peter; Sadjina, Severin; Mal'shukov, A. G.; Brataas, Arne

    2017-02-01

    We consider the spin-orbit-induced spin Hall effect and spin swapping in diffusive superconductors. By employing the nonequilibrium Keldysh Green's function technique in the quasiclassical approximation, we derive coupled transport equations for the spectral spin and particle distributions and for the energy density in the elastic scattering regime. We compute four contributions to the spin Hall conductivity, namely, skew scattering, side jump, anomalous velocity, and the Yafet contribution. The reduced density of states in the superconductor causes a renormalization of the spin Hall angle. We demonstrate that all four of these contributions to the spin Hall conductivity are renormalized in the same way in the superconducting state. In its simplest manifestation, spin swapping transforms a primary spin current into a secondary spin current with swapped current and polarization directions. We find that the spin-swapping coefficient is not explicitly but only implicitly affected by the superconducting gap through the renormalized diffusion coefficients. We discuss experimental consequences for measurements of the (inverse) spin Hall effect and spin swapping in four-terminal geometries. In our geometry, below the superconducting transition temperature, the spin-swapping signal is increased an order of magnitude while changes in the (inverse) spin Hall signal are moderate.

  15. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris, E-mail: hammel@physics.osu.edu [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-05-07

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  16. INJURIES IN DISC GOLF - A DESCRIPTIVE CROSS-SECTIONAL STUDY

    DEFF Research Database (Denmark)

    Rahbek, Martin Amadeus; Nielsen, Rasmus Oestergaard

    2016-01-01

    BACKGROUND: Disc golf is rapidly increasing in popularity and more than two million people are estimated to regularly participate in disc golf activities. Despite this popularity, the epidemiology of injuries in disc golf remains under reported. PURPOSE: The purpose of the present study was to in......BACKGROUND: Disc golf is rapidly increasing in popularity and more than two million people are estimated to regularly participate in disc golf activities. Despite this popularity, the epidemiology of injuries in disc golf remains under reported. PURPOSE: The purpose of the present study...... was to investigate the prevalence and anatomic distribution of injuries acquired through disc-golf participation in Danish disc golf players. METHODS: The study was a cross-sectional study conducted on Danish disc-golf players. In May 2015, invitations to complete a web-based questionnaire were spread online via...... social media, and around disc-golf courses in Denmark. The questionnaire included questions regarding disc-golf participation and the characteristics of injuries acquired through disc golf participation. The data was analyzed descriptively. RESULTS: An injury prevalence of 13.3% (95% CI: 6.7% to 19...

  17. On the illumination of neutron star accretion discs

    Science.gov (United States)

    Wilkins, D. R.

    2018-03-01

    The illumination of the accretion disc in a neutron star X-ray binary by X-rays emitted from (or close to) the neutron star surface is explored through general relativistic ray tracing simulations. The applicability of the canonical suite of relativistically broadened emission line models (developed for black holes) to discs around neutron stars is evaluated. These models were found to describe well emission lines from neutron star accretion discs unless the neutron star radius is larger than the innermost stable orbit of the accretion disc at 6 rg or the disc is viewed at high inclination, above 60° where shadowing of the back side of the disc becomes important. Theoretical emissivity profiles were computed for accretion discs illuminated by hotspots on the neutron star surfaces, bands of emission and emission by the entirety of the hot, spherical star surface and in all cases, the emissivity profile of the accretion disc was found to be well represented by a single power law falling off slightly steeper than r-3. Steepening of the emissivity index was found where the emission is close to the disc plane and the disc can appear truncated when illuminated by a hotspot at high latitude. The emissivity profile of the accretion disc in Serpens X-1 was measured and found to be consistent with a single unbroken power law with index q=3.5_{-0.4}^{+0.3}, suggestive of illumination by the boundary layer between the disc and neutron star surface.

  18. Time Localisation of Surface Defects on Optical Discs

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Wickerhauser, M.V.

    Many have experienced problems with their Compact Disc player when a disc with a scratch or a finger print is tried played. One way to improve the playability of discs with such a defect, is to locate the defect in time and then handle it in a special way. As a consequence this time localisation...

  19. Time Localisation of Surface Defects on Optical Discs

    DEFF Research Database (Denmark)

    Odgaard, Peter Fogh; Wickerhauser, M.V.

    2004-01-01

    Many have experienced problems with their Compact Disc Player when a disc with a scratch or a fingerprint is tried played. One way to improve the playability of discs with such a defect, is to locate the defect in time and then handle it in a special way. As a consequence this time localization...

  20. Higher Spins & Strings

    CERN Multimedia

    CERN. Geneva

    2014-01-01

    The conjectured relation between higher spin theories on anti de-Sitter (AdS) spaces and weakly coupled conformal field theories is reviewed. I shall then outline the evidence in favour of a concrete duality of this kind, relating a specific higher spin theory on AdS3 to a family of 2d minimal model CFTs. Finally, I shall explain how this relation fits into the framework of the familiar stringy AdS/CFT correspondence.

  1. Quantum spin quadrumer

    Science.gov (United States)

    Khatua, Subhankar; Shankar, R.; Ganesh, R.

    2018-02-01

    A fundamental motif in frustrated magnetism is the fully mutually coupled cluster of N spins, with each spin coupled to every other spin. Clusters with N =2 and 3 have been extensively studied as building blocks of square and triangular lattice antiferromagnets. In both cases, large-S semiclassical descriptions have been fruitfully constructed, providing insights into the physics of macroscopic magnetic systems. Here, we develop a semiclassical theory for the N =4 cluster. This problem has rich mathematical structure with a ground-state space that has nontrivial topology. We show that ground states are appropriately parametrized by a unit vector order parameter and a rotation matrix. Remarkably, in the low-energy description, the physics of the cluster reduces to that of an emergent free spin-S spin and a rigid rotor. This successfully explains the spectrum of the quadrumer and its associated degeneracies. However, this mapping does not hold in the vicinity of collinear ground states due to a subtle effect that arises from the nonmanifold nature of the ground-state space. We demonstrate this by an analysis of soft fluctuations, showing that collinear states have a larger number of soft modes. Nevertheless, as these singularities only occur on a subset of measure zero, the mapping to a spin and a rotor provides a good description of the quadrumer. We interpret thermodynamic properties of the quadrumer that are accessible in molecular magnets, in terms of the rotor and spin degrees of freedom. Our study paves the way for field theoretic descriptions of systems such as pyrochlore magnets.

  2. Spider Spinning for Dummies

    Science.gov (United States)

    Bird, Richard S.

    Spider spinning is a snappy name for the problem of listing the ideals of a totally acyclic poset in such a way that each ideal is computed from its predecessor in constant time. Such an algorithm is said to be loopless. Our aim in these lectures is to show how to calculate a loopless algorithm for spider spinning. The calculation makes use of the fundamental laws of functional programming and the real purpose of the exercise is to show these laws in action.

  3. Spin-engineered quantum dots

    OpenAIRE

    Fleurov, V.; Ivanov, V. A.; Peeters, F. M.; Vagner, I. D.

    2001-01-01

    Spatially nonhomogeneously spin polarized nuclei are proposed as a new mechanism to monitor electron states in a nanostructure, or as a means to createn and, if necessary, reshape such nanostructures in the course of the experiment. We found that a polarization of nulear spins may lift the spin polarization of the electron states in a nanostructure and, if sufficiently strong, leads to a polarization of the electron spins. Polarized nuclear spins may form an energy landscape capable of bindin...

  4. Theory of spin Hall effect

    OpenAIRE

    Chudnovsky, Eugene M.

    2007-01-01

    An extension of Drude model is proposed that accounts for spin and spin-orbit interaction of charge carriers. Spin currents appear due to combined action of the external electric field, crystal field and scattering of charge carriers. The expression for spin Hall conductivity is derived for metals and semiconductors that is independent of the scattering mechanism. In cubic metals, spin Hall conductivity $\\sigma_s$ and charge conductivity $\\sigma_c$ are related through $\\sigma_s = [2 \\pi \\hbar...

  5. Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation.

    Science.gov (United States)

    Lee, Jung Hwan; Lee, Sang-Ho

    2016-02-01

    Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more

  6. Clinical and Radiological Characteristics of Lumbosacral Lateral Disc Herniation in Comparison With Those of Medial Disc Herniation

    Science.gov (United States)

    Lee, Jung Hwan; Lee, Sang-Ho

    2016-01-01

    Abstract Lateral disc herniation (foraminal and extra foraminal) has clinical characteristics that are different from those of medial disc herniation (central and subarticular), including older age, more frequent radicular pain, and neurologic deficits. This is supposedly because lateral disc herniation mechanically irritates or compresses the exiting nerve root or dorsal root ganglion inside of a narrow canal more directly than medial disc herniation. The purpose of this study was to investigate clinical and radiological characteristics of lateral disc herniation in comparison with medial disc herniation. The 352 subjects diagnosed with localized lumbosacral disc herniation and followed up for at least 12 months after completion of treatment were included and divided into medial and lateral disc herniation groups, according to the anatomical location of the herniated disc in axial plain of magnetic resonance image. Clinical and radiological data were obtained and compared between the two groups. The lateral group included 74 (21%) patients and the medial group included 278 (79%). Mean age of the lateral group was significantly higher than that in the medial group. The lateral group showed a significantly larger proportion of patients with radiating leg pain and multiple levels of disc herniations than the medial group. No significant differences were found in terms of gender, duration of pain, pretreatment numeric rating scale, severity of disc herniation (protrusion and extrusion), and presence of weakness in leg muscles. The proportion of patients who underwent surgery was not significantly different between the 2 groups. However, the proportion of patients who accomplished successful pain reduction after treatment was significantly smaller in the lateral than in the medial group. In conclusion, patients with lateral disc herniation were older and had larger proportion of radiating leg pain than those with medial disc herniation. Lateral disc herniation was more

  7. [Low back pain and degenerative disc disease].

    Science.gov (United States)

    Jandrić, Slavica; Antić, Branislav

    2006-01-01

    Various clinical conditions can cause low back pain, and in most cases it is of a degenerative origin. Degenerative disc disease is a common condition which affects young to middle-aged men and women equally. Changes in the mechanical properties of the disc lead to degenerative arthritis in the intervertebral joints, osteophytes, and narrowing the intervertebral foramen or the spinal canal. Degenerative cascade, described by Kirkaldy-Willis, is the widely accepted pathophysiologic model describing the degenerative process as it affects the lumbar spine in 3 phases. There are two forms of low back pain secondary to degenerative disc disease: a) lumbalgia and b) lumbar radiculopathy. Limitation of movement, problems with balance, pain, loss of reflexes in the extremities, muscle weakness, loss of sensation or other signs of neurological damage can be found on physical examination. For accurate diagnosis, it is often necessary to combine clinical examination and sophisticated technology. Coservative treatment consists of rest, physical therapy, pharmacological therapy and injection therapy. Physical rehabilitation with active patient participation is a key approach to treatment of patients with discogenic pain. Physical therapy, occupational therapy and kinesitherapy are important for improving muscle strength, endurance, and flexibility. Disc surgery is performed if surgical intervention is required.

  8. Can Exercise Positively Influence the Intervertebral Disc?

    NARCIS (Netherlands)

    Belavý, Daniel L.; Albracht, Kirsten; Bruggemann, Gert Peter; Vergroesen, Pieter Paul A; van Dieën, Jaap H.

    2016-01-01

    To better understand what kinds of sports and exercise could be beneficial for the intervertebral disc (IVD), we performed a review to synthesise the literature on IVD adaptation with loading and exercise. The state of the literature did not permit a systematic review; therefore, we performed a

  9. Grand Challenges in Protoplanetary Disc Modelling

    NARCIS (Netherlands)

    Haworth, Thomas J.; Ilee, John D.; Forgan, Duncan H.; Facchini, Stefano; Price, Daniel J.; Boneberg, Dominika M.; Booth, Richard A.; Clarke, Cathie J.; Gonzalez, Jean-François; Hutchison, Mark A.; Kamp, Inga; Laibe, Guillaume; Lyra, Wladimir; Meru, Farzana; Mohanty, Subhanjoy; Panić, Olja; Rice, Ken; Suzuki, Takeru; Teague, Richard; Walsh, Catherine; Woitke, Peter; authors, Community

    2016-01-01

    The Protoplanetary Discussions conference-held in Edinburgh, UK, from 2016 March 7th-11th-included several open sessions led by participants. This paper reports on the discussions collectively concerned with the multi-physics modelling of protoplanetary discs, including the self-consistent

  10. Geršgorin discs revisited

    Czech Academy of Sciences Publication Activity Database

    Fiedler, Miroslav; Hall, F.J.; Marsli, R.

    2013-01-01

    Roč. 438, č. 1 (2013), s. 598-603 ISSN 0024-3795 Institutional support: RVO:67985807 Keywords : geometric multiplicity * algebra ic multiplicity * Geršgorin disc Subject RIV: BA - General Mathematics Impact factor: 0.983, year: 2013

  11. Inflammatory profiles in canine intervertebral disc degeneration

    NARCIS (Netherlands)

    Willems, Nicole; Tellegen, Anna R; Bergknut, Niklas; Creemers, Laura B; Wolfswinkel, Jeannette; Freudigmann, Christian; Benz, Karin; Grinwis, Guy C M; Tryfonidou, Marianna A; Meij, Björn P

    2016-01-01

    BACKGROUND: Intervertebral disc (IVD) disease is a common spinal disorder in dogs and degeneration and inflammation are significant components of the pathological cascade. Only limited studies have studied the cytokine and chemokine profiles in IVD degeneration in dogs, and mainly focused on gene

  12. Intervertebral disc herniation: prevalence and association with ...

    African Journals Online (AJOL)

    Method: A total of 120 adult patients who came for magnetic resonance imaging scan of the lumbosacral spine for a period of 1year in the department of Radiology University of Port-Harcourt Teaching Hospital. The end plates of 600 lumbar interspaces were graded for type, size and site of lumbar disc herniation. Results: ...

  13. Solid angle subtended by two circular discs

    International Nuclear Information System (INIS)

    Gilly, Louis.

    1978-09-01

    Methods of calculation of solid angles, subtended by two circular discs are analysed. Calculus are methodically classified as follow: series development Legendre polynomes, defined integral, elliptic integrals, Bessel integrals, multiple integrals, Monte Carlo method, electrostatic analogy. Applications in Nuclear Physics are added as examples. List of numeric tables completes bibliography [fr

  14. Fusion around cervical disc prosthesis: case report.

    NARCIS (Netherlands)

    Bartels, R.H.M.A.; Donk, R.

    2005-01-01

    OBJECTIVE AND IMPORTANCE: Cervical arthroplasty is a relatively new method to maintain motion after cervical anterior discectomy. Two cases are presented in which bony fusion occurred around a cervical disc prosthesis. CLINICAL PRESENTATION: A 30-year-old man and a 49-year-old woman underwent a

  15. Colloidal discs in nematic liquid crystals

    International Nuclear Information System (INIS)

    Silvestre, N M; Patricio, P; Tasinkevych, M; Andrienko, D; Gama, M M Telo da

    2004-01-01

    We use adaptive finite elements methods to investigate a variety of structures in inverted nematic emulsions numerically. In particular, we study dipolar and quadrupolar interactions between colloidal discs in two-dimensional nematics. The behaviour of colloidal particles near a substrate and at a nematic-isotropic interface are also considered

  16. The global structure of galactic discs

    NARCIS (Netherlands)

    Grijs, R. de

    1998-01-01

    A statistical study of global galaxy parameters can help to improve our understanding of galaxy formation processes. In this paper we present the analysis of global galaxy parameters based on optical and near-infrared observations of a large sample of edge-on disc galaxies. We found a correlation

  17. CT in diagnosis of recurrent vertebral disc hernias after preceding lumbar disc prolapse surgery

    International Nuclear Information System (INIS)

    Burval, S.; Nekula, J.; Vaverka, M.; Veliskova, J.

    1992-01-01

    20 patients with recurrent symptoms following operations for disc prolapse and resistant to treatment were studied by CT, using plain and enhanced images. The results have been analysed. In 10 patients a recurrence of disc prolapse was diagnosed, and this was confirmed surgically in 8 cases. In 2 patients there was epidural scarring. The findings indicate that differential diagnosis between scarring and recurring prolapse can by accurately made by this technique. (orig.) [de

  18. Transplantation of dedifferentiation fat cells promotes intervertebral disc regeneration in a rat intervertebral disc degeneration model.

    Science.gov (United States)

    Nakayama, Enshi; Matsumoto, Taro; Kazama, Tomohiko; Kano, Koichiro; Tokuhashi, Yasuaki

    2017-11-18

    Our group has reported that mature adipocyte-derived dedifferentiated fat (DFAT) cells show multilineage differentiation potential similar to that observed in mesenchymal stem cells. In the present study, we examined whether DFAT cell transplantation could contribute to intervertebral disc regeneration using a rat intervertebral disc degeneration (IDD) model. The IDD was created in Sprague-Dawley rats by puncturing at level of caudal intervertebral disc under fluoroscopy. One week after injury, rat DFAT cells (5 × 10 4 , DFAT group, n = 13) or phosphate-buffered saline (PBS, control group, n = 13) were injected into the intervertebral disc. Percent disc height index (%DHI) was measured every week and histology of injured disc was evaluated at 8 weeks after transplantation. Radiographic analysis revealed that the %DHI in the DFAT group significantly higher than that in the control group at 2-3 weeks after transplantation. Histological analysis revealed that ectopic formation of nucleus pulposus (NP)-like tissue at the outer layer of annulus fibrosus was frequently observed in the DFAT group but not in the control group. Transplantation experiments using green fluorescent protein (GFP)-labeled DFAT cells revealed that the ectopic NP-like tissue was positive for GFP, suggesting direct differentiation of DFAT cells into NP-like cells. In conclusion, DFAT cell transplantation promoted the regeneration of intervertebral disc and improved intervertebral disc height in the rat IDD model. Because adipose tissue is abundant and easily accessible, DFAT cell transplantation may be an attractive therapeutic strategy against IDD. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  19. [Efficacy of percutaneous laser disc decompression for radiculalgia due to lumbar disc hernia (149 patients)].

    Science.gov (United States)

    Morelet, Aude; Boyer, François; Vitry, Fabien; Ackah-Miezan, Stanley; Berquet, Renaud; Langlois, Sandrine; Brochot, Pascal; Breidt, Damien; Eschard, Jean-Paul; Etienne, Jean-Claude

    2007-11-01

    To assess the efficacy of percutaneous laser disc decompression for patients with radicular pain due to lumbar disc hernia and to identify factors that may predict outcome. The study included all patients treated with percutaneous laser disc decompression from May 2003 through May 2005 at Reims University Hospital and the Courlancy Clinic of Reims. Each patient had previous undergone at least six weeks of conventional medical treatment. The same technique, with either a laser diode or Nd: YAG, was used under endoscopic control and with neuroleptanalgesia. They were seen at 1, 3, 6 and 12 months. The principal evaluation criteria were the course of radicular pain, return to work, and need for surgery. We reexamined 149 patients 1 month after the procedure, 135 after 3 months, 102 after 6 months and 59 a year after the procedure. At a month after surgery, radicular pain had decreased by at least half, and sometimes even completely disappeared in 63.1% of patients at 1 month, 66.6% at 3 months, 73.5% at 6 months, and 83.1% at 12 months, while 24%, 50,4%, 61.2%, and 67.3%, respectively, had returned to work. No patient had serious complications. Finally, 45 of the 149 (30.2%) patients chose to have a traditional surgical procedure after percutaneous laser disc decompression. Percutaneous laser disc decompression is effective, noninvasive and well tolerated for patients with radicular pain due to lumbar disc hernia.

  20. Spin-Current and Spin-Splitting in Helicoidal Molecules Due to Spin-Orbit Coupling

    Science.gov (United States)

    Caetano, R. A.

    2016-03-01

    The use of organic materials in spintronic devices has been seriously considered after recent experimental works have shown unexpected spin-dependent electrical properties. The basis for the confection of any spintronic device is ability of selecting the appropriated spin polarization. In this direction, DNA has been pointed out as a potential candidate for spin selection due to the spin-orbit coupling originating from the electric field generated by accumulated electrical charges along the helix. Here, we demonstrate that spin-orbit coupling is the minimum ingredient necessary to promote a spatial spin separation and the generation of spin-current. We show that the up and down spin components have different velocities that give rise to a spin-current. By using a simple situation where spin-orbit coupling is present, we provide qualitative justifications to our results that clearly point to helicoidal molecules as serious candidates to integrate spintronic devices.

  1. Spin Torques in Systems with Spin Filtering and Spin Orbit Interaction

    KAUST Repository

    Ortiz Pauyac, Christian

    2016-06-19

    In the present thesis we introduce the reader to the field of spintronics and explore new phenomena, such as spin transfer torques, spin filtering, and three types of spin-orbit torques, Rashba, spin Hall, and spin swapping, which have emerged very recently and are promising candidates for a new generation of memory devices in computer technology. A general overview of these phenomena is presented in Chap. 1. In Chap. 2 we study spin transfer torques in tunnel junctions in the presence of spin filtering. In Chap. 3 we discuss the Rashba torque in ferromagnetic films, and in Chap. 4 we study spin Hall effect and spin swapping in ferromagnetic films, exploring the nature of spin-orbit torques based on these mechanisms. Conclusions and perspectives are summarized in Chap. 5.

  2. MR imaging of lumbar herniated intervertebral disc and spinal stenosis: Correlation with CT

    Energy Technology Data Exchange (ETDEWEB)

    Lee, Won Jae; Park, Kil Sun; Chang, Kee Hyun; Han, Moon Hee; Kim, Hyun Jip; Han, Man Chung; Kim, Chu Wan [Seoul National University College of Medicine, Seoul (Korea, Republic of)

    1989-12-15

    MR imagings obtained in 40 patients with surgically proven lumbar herniated intervertebral disc (HIVD) and/or spinal stenosis were retrospectively analysed and compared with CT scans, in order to evaluate the MR findings of HIVD and spinal stenosis, and to assess the diagnostic accuracy of MR. The MR imaging was performed on a 2.0 T superconducting unit, using multislice spin echo (SE) and gradient echo (GE) techniques. The results were as follows: 1. The texture of vertebral body with spinal stenosis had the tendency to be more heterogeneous than that with HIVD. 2. The signal intensity of the diseased disc was isointense relative to normal disc in 81 % (60/74) and the remainder (19%) was hypointense on both T1 weighted SE and GE images. There was no significant difference in signal intensity among HIVD, HIVD combined with spinal stenosis and spinal stenosis groups, but there was the tendency of lower signal intensity of the diseased disc in patients with severe degenerative change of spine in both T1 weighted SE imaged and GE image. 3. The diagnostic accuracy of MR was 92%, which was similar to that of CT. 4. T1 weighted SE image appears superior to GE image in evaluation of most of the structural differentiation, but as for differentiating between lumina and ligamentum flavum, and for the vacuum phenomenon, GE image seems to be better than T1 weighted SE image. In conclusion, MR appears to be better than CT as a initial imaging modality in evaluation of the patients with suspected lumbar spinal stenosis or HIVD because MR has the capability of demonstrating rupture of anulus fibrosus in sagittal plane.

  3. MR findings of the transligamentous type of the herniated lumbar disc

    Energy Technology Data Exchange (ETDEWEB)

    Kang, Byung Chul; Kim, Dong Ik; Yoon, Choon Sik; Suh, Jung Ho [College of Medicine, Yonsei University, Seoul (Korea, Republic of)

    1994-03-15

    The purpose of this study is to describe the findings of the transligamnetous type of the herniated lumbar disc (HLD) with magnetic resonance MR imaging. We retrospectively analyzed the MR images of surgically proven 20 cases of transligamentous type of HLD from January 1, 1992 to August 20, 1992. The MR imaging was performed with 1.0T MR unit, using sagittal spin echo (SE) and axial gradient echo (GE) techniques. The results were as follows; 1) the interruption of black line of the posterior longitudinal ligament (PLL) was identified in 19 levels and 17 levels in sagittal SE and axial GE images, retrospectively; 2) the widening of adjacent epidural fat space was demonstrated in 16 cases of central or posterolateral HLD. The herniated disc material, as compared with the parent intervertebral disc, showed intermediate signal intensity (SI) in 19 and low SI in 1 level on T1WI, high SI in 10, intermediate SI in 7, low SI in levels on T2WI, and high SI in 10, intermediate SI in 9, low SI in 1 level on GE images. The most important sign of the transligamentous type HLD on MRI was the interruption of the black line with additional finding of the widening of adjacent epidural fat space. The MR signal intensity of the herniated disc was variable. Axial GE image was valuable for the evaluation of the direction of HLD and it relationship with neural structure, but had no addiational information for the degree and biochemical change of HLD over SE image.

  4. The diagnosis of internal disc disruption with CT discography

    International Nuclear Information System (INIS)

    Liu Miao; Chen Xingcan; Li Xiaohong; Pan Yongqin

    2008-01-01

    Objective: To study the value of diagnosis for internal disc disruption (IDD)with CT discography(CTD). Methods: 42 discs of 32 patients showing no disc herniation on CT or MRI, but suffering from chronic low back pain, were undertaken CTD to work out the types of CTD with correlation between contrast medium dosages and the induction of pain. Results: CTD demonstrated 4 types of IDD which was individually correlated with the contrast dosages and induced pain; furthermore the dosages for positive and negative disc cases showed significant differece (P<0.01). Conclusions: CTD can show the direct sign of internal disc disruption, providing more information than conventional discography. (authors)

  5. Prevalence of annular tears and disc herniations on MR images of the cervical spine in symptom free volunteers

    International Nuclear Information System (INIS)

    Ernst, C.W.; Stadnik, T.W.; Peeters, E.; Breucq, C.; Osteaux, M.J.C.

    2005-01-01

    Study design: Prospective MR analysis of the cervical spine of 30 asymptomatic volunteers. Objectives: To evaluate the prevalence of annular tears, bulging discs, disc herniations and medullary compression on T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance (MR) images of the cervical spine in symptom free volunteers. Summary of background data: Few studies have reported the prevalence of cervical disc herniations in asymptomatic people, none have reported the prevalence of cervical annular tears on MR images of symptom free volunteers. Materials and methods: Thirty symptom-free volunteers (no history or symptoms related to the cervical spine) were examined using sagittal T2-weighted fast spin-echo (SE), sagittal gadolinium-enhanced T1-weighted SE imaging and axial T2 * -weighted gradient echo (GRE). The prevalence of bulging discs, focal protrusions, extrusions, nonenhancing or enhancing annular tears and medullary compression were assessed. Results: The prevalence of bulging disk and focal disk protrusions was 73% (22 volunteers) and 50% (15 volunteers), respectively. There was one extrusion (3%). Eleven volunteers had annular tears at one or more levels (37%) and 94% of the annular tears enhanced after contrast injection. Asymptomatic medullary compression was found in four patients (13%). Conclusion: Annular tears and focal disk protrusions are frequently found on MR imaging of the cervical spine, with or without contrast enhancement, in asymptomatic population. The extruded disk herniation and medullary compression are unusual findings in a symptom-free population

  6. Design and Development of Micro-Power Generating Device for Biomedical Applications of Lab-on-a-Disc

    Science.gov (United States)

    Joseph, Karunan; Ibrahim, Fatimah; Cho, Jongman; Thio, Tzer Hwai Gilbert; Al-Faqheri, Wisam; Madou, Marc

    2015-01-01

    The development of micro-power generators for centrifugal microfluidic discs enhances the platform as a green point-of-care diagnostic system and eliminates the need for attaching external peripherals to the disc. In this work, we present micro-power generators that harvest energy from the disc’s rotational movement to power biomedical applications on the disc. To implement these ideas, we developed two types of micro-power generators using piezoelectric films and an electromagnetic induction system. The piezoelectric-based generator takes advantage of the film’s vibration during the disc’s rotational motion, whereas the electromagnetic induction-based generator operates on the principle of current generation in stacks of coil exposed to varying magnetic flux. We have successfully demonstrated that at the spinning speed of 800 revolutions per minute (RPM) the piezoelectric film-based generator is able to produce up to 24 microwatts using 6 sets of films and the magnetic induction-based generator is capable of producing up to 125 milliwatts using 6 stacks of coil. As a proof of concept, a custom made localized heating system was constructed to test the capability of the magnetic induction-based generator. The heating system was able to achieve a temperature of 58.62°C at 2200 RPM. This development of lab-on-a-disc micro power generators preserves the portability standards and enhances the future biomedical applications of centrifugal microfluidic platforms. PMID:26422249

  7. Prevalence of annular tears and disc herniations on MR images of the cervical spine in symptom free volunteers

    Energy Technology Data Exchange (ETDEWEB)

    Ernst, C.W. [Department of Radiology and Medical Imaging, University Hospital V.U.B., Laarbeeklaan 101, 1090 Brussels (Belgium)]. E-mail: ernstcaroline@hotmail.com; Stadnik, T.W. [Department of Radiology and Medical Imaging, University Hospital V.U.B., Laarbeeklaan 101, 1090 Brussels (Belgium); Peeters, E. [Department of Radiology and Medical Imaging, University Hospital V.U.B., Laarbeeklaan 101, 1090 Brussels (Belgium); Breucq, C. [Department of Radiology and Medical Imaging, University Hospital V.U.B., Laarbeeklaan 101, 1090 Brussels (Belgium); Osteaux, M.J.C. [Department of Radiology and Medical Imaging, University Hospital V.U.B., Laarbeeklaan 101, 1090 Brussels (Belgium)

    2005-09-01

    Study design: Prospective MR analysis of the cervical spine of 30 asymptomatic volunteers. Objectives: To evaluate the prevalence of annular tears, bulging discs, disc herniations and medullary compression on T2-weighted and gadolinium-enhanced T1-weighted magnetic resonance (MR) images of the cervical spine in symptom free volunteers. Summary of background data: Few studies have reported the prevalence of cervical disc herniations in asymptomatic people, none have reported the prevalence of cervical annular tears on MR images of symptom free volunteers. Materials and methods: Thirty symptom-free volunteers (no history or symptoms related to the cervical spine) were examined using sagittal T2-weighted fast spin-echo (SE), sagittal gadolinium-enhanced T1-weighted SE imaging and axial T2{sup *}-weighted gradient echo (GRE). The prevalence of bulging discs, focal protrusions, extrusions, nonenhancing or enhancing annular tears and medullary compression were assessed. Results: The prevalence of bulging disk and focal disk protrusions was 73% (22 volunteers) and 50% (15 volunteers), respectively. There was one extrusion (3%). Eleven volunteers had annular tears at one or more levels (37%) and 94% of the annular tears enhanced after contrast injection. Asymptomatic medullary compression was found in four patients (13%). Conclusion: Annular tears and focal disk protrusions are frequently found on MR imaging of the cervical spine, with or without contrast enhancement, in asymptomatic population. The extruded disk herniation and medullary compression are unusual findings in a symptom-free population.

  8. Optical spin generation/detection and spin transport lifetimes

    International Nuclear Information System (INIS)

    Miah, M. Idrish

    2011-01-01

    We generate electron spins in semiconductors by optical pumping. The detection of them is also performed by optical technique using time-resolved pump-probe photoluminescence polarization measurements in the presence of an external magnetic field perpendicular to the generated spin. The spin polarization in dependences of the pulse length, pump-probe delay and external magnetic field is studied. From the dependence of spin-polarization on the delay of the probe, the electronic spin transport lifetimes and the spin relaxation frequencies as a function of the strength of the magnetic field are estimated. The results are discussed based on hyperfine effects for interacting electrons.

  9. Optical spin generation/detection and spin transport lifetimes

    Energy Technology Data Exchange (ETDEWEB)

    Miah, M. Idrish, E-mail: m.miah@griffith.edu.au [Department of Physics, University of Chittagong, Chittagong 4331 (Bangladesh)

    2011-02-25

    We generate electron spins in semiconductors by optical pumping. The detection of them is also performed by optical technique using time-resolved pump-probe photoluminescence polarization measurements in the presence of an external magnetic field perpendicular to the generated spin. The spin polarization in dependences of the pulse length, pump-probe delay and external magnetic field is studied. From the dependence of spin-polarization on the delay of the probe, the electronic spin transport lifetimes and the spin relaxation frequencies as a function of the strength of the magnetic field are estimated. The results are discussed based on hyperfine effects for interacting electrons.

  10. Fas ligand exists on intervertebral disc cells: a potential molecular mechanism for immune privilege of the disc.

    Science.gov (United States)

    Takada, Toru; Nishida, Kotaro; Doita, Minoru; Kurosaka, Masahiro

    2002-07-15

    Rat and human intervertebral disc specimens were examined immunohistochemically. Reverse transcription polymerase chain reaction (RT-PCR) analysis was also performed on rat disc tissue to demonstrate the existence of Fas ligand. To clarify the existence of Fas ligand on intact intervertebral disc cells. The nucleus pulposus has been reported to be an immune-privileged site. The immune-privileged characteristic in other tissues such as the retina and testis has been attributed to the local expression of Fas ligand, which acts by inducing apoptosis of invading Fas-positive T-cells. The existence of Fas ligand in normal disc cells has not yet been addressed. Skeletally mature SD male rats were killed, and the coccygeal discs were harvested. Human disc specimens were obtained from idiopathic scoliosis patients during surgical procedures. Immunohistochemical staining for Fas ligand was performed for cross-sections of the discs by standard procedures. Reverse transcription polymerase chain reaction analysis was also carried out to demonstrate Fas ligand mRNA expression on rat intervertebral discs. Testes of the rats were used for positive controls, and muscles were used for negative controls. The sections were observed by light microscopy. The nucleus pulposus cells exhibited intense positive immune staining for Fas ligand. The outer anulus fibrosus cells and notochordal cells exhibited little immunopositivity. The positive controls exhibited positive immune staining, and the negative control showed no immunopositivity. The result of RT-PCR confirmed the existence of Fas ligand in disc cells. The human nucleus pulposus cells showed a similar predilection to rat disc cells. We demonstrated the existence of Fas ligand on disc cells, which should play a key role in the potential molecular mechanism to maintain immune privilege of the disc. Immune privilege and Fas ligand expression of the intervertebral disc may provide a new insight for basic science research as well as

  11. MR image assessment of disc configuration and degree of anterior disc displacement in internal derangement related to age

    Energy Technology Data Exchange (ETDEWEB)

    Igarashi, Chinami; Kobayashi, Kaoru; Imanaka, Masahiro; Yuasa, Masao; Yamamoto, Akira [Tsurumi Univ., Yokohama (Japan). School of Dental Medicine

    1999-03-01

    This study was designed to evaluate the configuration of the articular disc and degree of anterior disc displacement on magnetic resonance (MR) imagings in temporomandibular joints (TMJs) with internal derangement. A total of 363 joints diagnosed as having anterior disc displacement with reduction (ADD w R) and 523 joints diagnosed as having anterior disc displacement without reduction (ADD wo R) by MR imaging were examined. These joints did not show severe osseous changes on the condylar head or glenoid fossa. We assessed the configuration of the articular disc and degree of anterior disc displacement. In the ADD w R group, 82.6% of the articular discs showed biconcave configuration; enlargement of the posterior band in 4.6%, biconvex configuration in 0.5%, and others in 10.7%. Moreover 62.5% of the discs showed a slight degree of anterior disc displacement; were 27.2% moderately displaced and were 10.2% severe displaced. The prevalence of slightly displaced discs was higher in the TMJs of cases over 50 years of age than in cases under 30 years in the ADD w R group. On the other hand, in the ADD wo R group 35.9% of the articular discs showed biconcave configuration; enlargement of the posterior band in 12.6%, biconvex configuration in 25.4%, and others in 22.3%. Furthermore, 4.4% of the discs were slightly displaced; 43.9% moderately displaced and 51.6% were severely displaced. The prevalence of severely displaced and deformed discs in joints of cases over 40 years of age was high in the ADD wo R group. The prevalence of slightly displaced biconcave discs was higher in the ADD w R group. The other hand, the prevalence of severely displaced deformed discs was higher in the ADD wo R group. MR findings of internal derangement of the TMJ were found to be significantly correlated with age. (author)

  12. Be discs in binary systems - II. Misaligned orbits

    Science.gov (United States)

    Cyr, I. H.; Jones, C. E.; Panoglou, D.; Carciofi, A. C.; Okazaki, A. T.

    2017-10-01

    We use a smoothed particle hydrodynamics (SPH) code to examine the effects of misaligned binary companions on Be star discs. We systematically vary the degree of misalignment between the disc and the binary orbit, as well as the disc viscosity and orbital period to study their effects on the density in the inner and outer parts of the disc. We find that varying the degree of misalignment, the viscosity and the orbital period affects both the truncation radius and the density structure of the outer disc, while the inner disc remains mostly unaffected. We also investigate the tilting of the disc in the innermost part of the disc and find the tilt increases with radius until reaching a maximum around 5 stellar radii. The direction of the line of nodes, with respect to the equator of the central star, is found to be offset compared to the orbital line of nodes, and to vary periodically in time, with a period of half a orbital phase. We also compare the scaleheight of our discs with the analytical scaleheight of an isothermal disc, which increases with radius as r1.5. We find that this formula reproduces the scaleheight well for both aligned and misaligned systems but underestimates the scaleheight in regions of the disc where density enhancements develop.

  13. Clinical study of CT discography for the lumbar disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Sakamoto, Tadashi (Yamaguchi Univ., Ube (Japan). School of Medicine)

    1990-08-01

    The purpose of this clinical study was to introduce technique for correct positioning of the needle into the center of the disc for discography by means of CT analysis and also to clarify usefulness of CT discography for diagnosis of the lumbar disc herniation. We have taken CT analysis in order to determine correct place and the angle of inserting the needle. This measurement provides easy needle insertion. Unless the needle tip places center of disc, discogram false positive or negative will occur as a result. The materials of this study are 222 discs of 105 cases with the lumbar disc herniation. Comparative study of the findings among myelography, discography and CT discography was investigated. The results indicated that CT discography demonstrates the most clear findings and is useful in the diagnosis of lumbar disc herniation, especially in obtaining detailed observation of herniated discs. (author).

  14. Computer assisted characterization of cervical intervertebral disc degeneration in MRI

    Science.gov (United States)

    Michopoulou, S.; Boniatis, I.; Costaridou, L.; Cavouras, D.; Panagiotopoulos, E.; Panayiotakis, G.

    2009-05-01

    A texture-based pattern recognition system is proposed for the automatic characterization of cervical intervertebral disc degeneration from saggital magnetic resonance images of the spine. A case sample of 50 manually segmented ROIs, corresponding to 25 normal and 25 degenerated discs, was analyzed and textural features were generated from each disc-ROI. Student's t-test verified the existence of statistically significant differences between textural feature values generated from normal and degenerated discs. This finding is indicative of disc image texture differentiation due to the degeneration of the disc. The generated features were employed in the design of a pattern recognition system based on the Least Squares Minimum Distance classifier. The system achieved a classification accuracy of 94{%} and it may be of value to physicians for the assessment of cervical intervertebral disc degeneration in MRI.

  15. Examination of turbine discs from nuclear power plants

    International Nuclear Information System (INIS)

    Czajkowski, C.J.; Weeks, J.R.

    1982-01-01

    Investigations were performed on a cracked turbine disc from the Cooper Nuclear Power Station, and on two failed turbine discs (governor and generator ends) from the Yankee-Rowe Nuclear Power Station. Cooper is a boiling water reactor (BWR) which went into commercial operation in July 1974, and Yankee-Rowe is a pressurized water reactor (PWR) which went into commercial operation in June 1961. Cracks were identified in the bore of the Cooper disc after 41,913 hours of operation, and the disc removed for repair. At Yankee-Rowe two discs failed after 100,000 hours of operation. Samples of the Cooper disc and both Yankee-Rowe disc (one from the governor and one from the generator end of the LP turbine) were sent to Brookhaven National Laboratory (BNL) for failure analysis

  16. Thermoelectric spin voltage in graphene.

    Science.gov (United States)

    Sierra, Juan F; Neumann, Ingmar; Cuppens, Jo; Raes, Bart; Costache, Marius V; Valenzuela, Sergio O

    2018-02-01

    In recent years, new spin-dependent thermal effects have been discovered in ferromagnets, stimulating a growing interest in spin caloritronics, a field that exploits the interaction between spin and heat currents 1,2 . Amongst the most intriguing phenomena is the spin Seebeck effect 3-5 , in which a thermal gradient gives rise to spin currents that are detected through the inverse spin Hall effect 6-8 . Non-magnetic materials such as graphene are also relevant for spin caloritronics, thanks to efficient spin transport 9-11 , energy-dependent carrier mobility and unique density of states 12,13 . Here, we propose and demonstrate that a carrier thermal gradient in a graphene lateral spin valve can lead to a large increase of the spin voltage near to the graphene charge neutrality point. Such an increase results from a thermoelectric spin voltage, which is analogous to the voltage in a thermocouple and that can be enhanced by the presence of hot carriers generated by an applied current 14-17 . These results could prove crucial to drive graphene spintronic devices and, in particular, to sustain pure spin signals with thermal gradients and to tune the remote spin accumulation by varying the spin-injection bias.

  17. Noise in tunneling spin current across coupled quantum spin chains

    Science.gov (United States)

    Aftergood, Joshua; Takei, So

    2018-01-01

    We theoretically study the spin current and its dc noise generated between two spin-1 /2 spin chains weakly coupled at a single site in the presence of an over-population of spin excitations and a temperature elevation in one subsystem relative to the other, and we compare the corresponding transport quantities across two weakly coupled magnetic insulators hosting magnons. In the spin chain scenario, we find that applying a temperature bias exclusively leads to a vanishing spin current and a concomitant divergence in the spin Fano factor, defined as the spin current noise-to-signal ratio. This divergence is shown to have an exact analogy to the physics of electron scattering between fractional quantum Hall edge states and not to arise in the magnon scenario. We also reveal a suppression in the spin current noise that exclusively arises in the spin chain scenario due to the fermion nature of the spin-1/2 operators. We discuss how the spin Fano factor may be extracted experimentally via the inverse spin Hall effect used extensively in spintronics.

  18. Overview of spin physics

    Energy Technology Data Exchange (ETDEWEB)

    Yokosawa, A.

    1992-12-23

    Spin physics activities at medium and high energies became significantly active when polarized targets and polarized beams became accessible for hadron-hadron scattering experiments. My overview of spin physics will be inclined to the study of strong interaction using facilities at Argonne ZGS, Brookhaven AGS (including RHIC), CERN, Fermilab, LAMPF, an SATURNE. In 1960 accelerator physicists had already been convinced that the ZGS could be unique in accelerating a polarized beam; polarized beams were being accelerated through linear accelerators elsewhere at that time. However, there was much concern about going ahead with the construction of a polarized beam because (i) the source intensity was not high enough to accelerate in the accelerator, (ii) the use of the accelerator would be limited to only polarized-beam physics, that is, proton-proton interaction, and (iii) p-p elastic scattering was not the most popular topic in high-energy physics. In fact, within spin physics, [pi]-nucleon physics looked attractive, since the determination of spin and parity of possible [pi]p resonances attracted much attention. To proceed we needed more data beside total cross sections and elastic differential cross sections; measurements of polarization and other parameters were urgently needed. Polarization measurements had traditionally been performed by analyzing the spin of recoil protons. The drawbacks of this technique are: (i) it involves double scattering, resulting in poor accuracy of the data, and (ii) a carbon analyzer can only be used for a limited region of energy.

  19. Queixas auditivas de disc jockeys da cidade de Recife Auditory complaints in disc jockeys in Recife

    Directory of Open Access Journals (Sweden)

    Eliza Maia de Britto Macedo

    2011-06-01

    Full Text Available OBJETIVO: investigar a ocorrência de queixas auditivas em disc jockeys da cidade de Recife/PE. MÉTODOS: foi realizada uma entrevista com 30 disc jockeys, com idade entre 19 e 28 anos, abordando informações ocupacionais, conhecimentos gerais sobre o ruído e queixas auditivas (diminuição da acuidade auditiva, desconforto a sons intensos, zumbido, sensação de ouvido abafado e otalgia. A análise foi realizada por meio de abordagem quantitativa, utilizando o teste estatístico t-student. RESULTADOS: dentre os dados mais relevantes, destacam-se: 46,7% dos disc jockeys apresentaram, espontaneamente, queixas auditivas, em especial, a diminuição da acuidade auditiva (relatada por todos os sujeitos; 14 disc jockeys (46,67% referiram desconforto a sons intensos e 13 (43,33% mencionaram zumbido. Todos afirmaram ter conhecimento sobre os riscos do ruído para a saúde auditiva, mas 76,7% não realizam qualquer medida preventiva de suas consequências. A perda auditiva foi referida pelos sujeitos como o principal risco da exposição a níveis intensos de pressão sonora. CONCLUSÃO: todos os disc jockeys apresentaram queixa de perda auditiva e, entre as demais queixas auditivas, destacaram-se o desconforto a sons intensos e o zumbido. Tendo em vista a irreversibilidade da perda auditiva induzida por elevados níveis de pressão sonora, os disc jockeys devem ser periodicamente avaliados a fim de que se confirme ou não a perda auditiva de que se queixaram e, caso ela exista, deve ser monitorada para que seja passível de intervenção pelo fonoaudiólogo. Desta forma, percebe-se a necessidade de atuação da Fonoaudiologia junto aos disc jockeys, uma vez que poder-se-á propiciar a otimização do exercício profissional com o mínimo de risco possível.PURPOSE: to investigate the occurrence of auditory complaints in disc jockeys from the city of Recife/PE. METHODS: an interview was carried through with 30 disc jockeys aged between 19 and 48 years

  20. Total disc replacement for chronic back pain in the presence of disc degeneration.

    Science.gov (United States)

    Jacobs, Wilco; Van der Gaag, Niels A; Tuschel, Alexander; de Kleuver, Marinus; Peul, Wilco; Verbout, A J; Oner, F Cumhur

    2012-09-12

    In the search for better surgical treatment of chronic low-back pain (LBP) in the presence of disc degeneration, total disc replacement has received increasing attention in recent years. A possible advantage of total disc replacement compared with fusion is maintained mobility at the operated level, which has been suggested to reduce the chance of adjacent segment degeneration. The aim of this systematic review was to assess the effect of total disc replacement for chronic low-back pain in the presence of lumbar disc degeneration compared with other treatment options in terms of patient-centred improvement, motion preservation and adjacent segment degeneration. A comprehensive search in Cochrane Back Review Group (CBRG) trials register, CENTRAL, MEDLINE, EMBASE, BIOSIS, ISI, and the FDA register was conducted. We also checked the reference lists and performed citation tracking of included studies. We included randomised controlled trials (RCTs) comparing total disc replacement with any other intervention for degenerative disc disease. We assessed risk of bias per study using the criteria of the CBRG. Quality of evidence was graded according to the GRADE approach. Two review authors independently selected studies and assessed risk of bias of the studies. Results and upper bounds of confidence intervals were compared against predefined clinically relevant differences. We included 40 publications, describing seven unique RCT's. The follow-up of the studies was 24 months, with only one extended to five years. Five studies had a low risk of bias, although there is a risk of bias in the included studies due to sponsoring and absence of any kind of blinding. One study compared disc replacement against rehabilitation and found a statistically significant advantage in favour of surgery, which, however, did not reach the predefined threshold for clinical relevance. Six studies compared disc replacement against fusion and found that the mean improvement in VAS back pain was

  1. Synthetic spider silk fibers spun from Pyriform Spidroin 2, a glue silk protein discovered in orb-weaving spider attachment discs.

    Science.gov (United States)

    Geurts, Paul; Zhao, Liang; Hsia, Yang; Gnesa, Eric; Tang, Simon; Jeffery, Felicia; La Mattina, Coby; Franz, Andreas; Larkin, Leah; Vierra, Craig

    2010-12-13

    Spider attachment disc silk fibers are spun into a viscous liquid that rapidly solidifies, gluing dragline silk fibers to substrates for locomotion or web construction. Here we report the identification and artificial spinning of a novel attachment disc glue silk fibroin, Pyriform Spidroin 2 (PySp2), from the golden orb weaver Nephila clavipes . MS studies support PySp2 is a constituent of the pyriform gland that is spun into attachment discs. Analysis of the PySp2 protein architecture reveals sequence divergence relative to the other silk family members, including the cob weaver glue silk fibroin PySp1. PySp2 contains internal block repeats that consist of two subrepeat units: one dominated by Ser, Gln, and Ala and the other Pro-rich. Artificial spinning of recombinant PySp2 truncations shows that the Ser-Gln-Ala-rich subrepeat is sufficient for the assembly of polymeric subunits and subsequent fiber formation. These studies support that both orb- and cob-weaving spiders have evolved highly polar block-repeat sequences with the ability to self-assemble into fibers, suggesting a strategy to allow fiber fabrication in the liquid environment of the attachment discs.

  2. Low back pain associated with lumbar disc herniation: role of moderately degenerative disc and annulus fibrous tears

    Science.gov (United States)

    Yang, Hao; Liu, Hui; Li, Zemin; Zhang, Kuibo; Wang, Jianru; Wang, Hua; Zheng, Zhaomin

    2015-01-01

    Lumbar disc herniation is one of the most common spinal degenerative disorders which may lead to low back pain (LBP) and radicular leg pain. However, it remains difficult to diagnose a degenerative herniated disc as the LBP generator in clinical practice. The purpose of this study is to explore the characteristic changes of a herniated disc causing LBP on MRI and to clarify the underlying role of inflammatory mediators and annulus fibrous (AF) tears in LBP generation associated with disc herniation. We prospectively collected intervertebral disc specimens and MRI from 57 single-segment disc herniation patients with radiculopathy. All subjects were grouped according to LBP occurrence or disc degeneration severity for the comparison of inflammatory mediators’ expression and AF tears occurrence (High Intensity Zone, HIZ, on MRI). LBP incidence under circumstances of different degeneration severity with or without HIZ was further analyzed. Both LBP incidence and Inflammatory mediators expression in moderately degenerated group was higher than mildly and severely degenerative groups. HIZ incidence was higher in moderately and severely degenerated groups. LBP incidence in the patients with both moderately degenerated discs and HIZ was 86.7%, much higher than the rest of the patient population. In conclusion, the high expression of inflammatory mediators with AF tears causes LBP associated with disc herniation. Moderately degenerative disc with HIZ is MRI morphological change of herniated disc causing LBP, which can be applied to diagnose LBP. PMID:25932092

  3. Optic disc and peripapillary retinal nerve fiber layer characteristics associated with glaucomatous optic disc in young myopia.

    Science.gov (United States)

    Lee, Jong Eun; Sung, Kyung Rim; Park, Ji Min; Yoon, Joo Young; Kang, Sung Yong; Park, Sung Bae; Koo, Hyung Jin

    2017-03-01

    To explore optic disc and peripapillary retinal nerve fiber layer (RNFL) features associated with glaucomatous optic disc (GOD) in young myopia. Presence of GOD, optic disc tilt, and disc torsion were determined using fundus photographs. If the measured disc tilt ratio was >1.3, the optic disc was classified as tilted. Optic disc torsion was defined as a >15° deviation in the long axis of the optic disc from the vertical meridian. The average and four quadrants RNFL thicknesses were assessed using spectral domain optical coherence tomography (SD-OCT). Logistic regression analyses were performed to identify factors associated with the presence of GOD. Nine hundred and sixty myopic subjects were recruited from four refractive surgery clinic databases. The mean age was 26.6 ± 5.7 years and spherical equivalent (SE) was -5.5 ± 2.5 diopters. Among 960 eyes, 26 (2.7%) received GOD group classification. Among 934 normal eyes, 290 (31.0%) had titled optic discs. Eighteen eyes (69.2%) in the GOD group had tilted optic discs. When compared to normal eyes, the GOD group had significantly higher tilt ratios (1.4 ± 0.2 vs. 1.2 ± 0.1, p Optic disc tilt was found in approximately one-third of young myopic eyes and was independently associated with the presence of GOD.

  4. Quantum spin transistor with a Heisenberg spin chain

    Science.gov (United States)

    Marchukov, O. V.; Volosniev, A. G.; Valiente, M.; Petrosyan, D.; Zinner, N. T.

    2016-01-01

    Spin chains are paradigmatic systems for the studies of quantum phases and phase transitions, and for quantum information applications, including quantum computation and short-distance quantum communication. Here we propose and analyse a scheme for conditional state transfer in a Heisenberg XXZ spin chain which realizes a quantum spin transistor. In our scheme, the absence or presence of a control spin excitation in the central gate part of the spin chain results in either perfect transfer of an arbitrary state of a target spin between the weakly coupled input and output ports, or its complete blockade at the input port. We also discuss a possible proof-of-concept realization of the corresponding spin chain with a one-dimensional ensemble of cold atoms with strong contact interactions. Our scheme is generally applicable to various implementations of tunable spin chains, and it paves the way for the realization of integrated quantum logic elements. PMID:27721438

  5. Spinning fluids reactor

    Science.gov (United States)

    Miller, Jan D; Hupka, Jan; Aranowski, Robert

    2012-11-20

    A spinning fluids reactor, includes a reactor body (24) having a circular cross-section and a fluid contactor screen (26) within the reactor body (24). The fluid contactor screen (26) having a plurality of apertures and a circular cross-section concentric with the reactor body (24) for a length thus forming an inner volume (28) bound by the fluid contactor screen (26) and an outer volume (30) bound by the reactor body (24) and the fluid contactor screen (26). A primary inlet (20) can be operatively connected to the reactor body (24) and can be configured to produce flow-through first spinning flow of a first fluid within the inner volume (28). A secondary inlet (22) can similarly be operatively connected to the reactor body (24) and can be configured to produce a second flow of a second fluid within the outer volume (30) which is optionally spinning.

  6. Spin gating electrical current

    Science.gov (United States)

    Ciccarelli, C.; Zârbo, L. P.; Irvine, A. C.; Campion, R. P.; Gallagher, B. L.; Wunderlich, J.; Jungwirth, T.; Ferguson, A. J.

    2012-09-01

    The level of the chemical potential is a fundamental parameter of the electronic structure of a physical system, which consequently plays an important role in defining the properties of active electrical devices. We directly measure the chemical potential shift in the relativistic band structure of the ferromagnetic semiconductor (Ga,Mn)As, controlled by changes in its magnetic order parameter. Our device comprises a non-magnetic aluminum single electron channel capacitively coupled to the (Ga,Mn)As gate electrode. The chemical potential shifts of the gate are directly read out from the shifts in the Coulomb blockade oscillations of the single electron transistor. The experiments introduce a concept of spin gating electrical current. In our spin transistor spin manipulation is completely removed from the electrical current carrying channel.

  7. SPIN-selling

    CERN Document Server

    Rackham, Neil

    1995-01-01

    True or false? In selling high-value products or services: "closing" increases your chance of success; it is essential to describe the benefits of your product or service to the customer; objection handling is an important skill; and open questions are more effective than closed questions. All false, says Neil Rackham. He and his team studied more than 35,000 sales calls made by 10,000 sales people in 23 countries over 12 years. Their findings revealed that many of the methods developed for selling low-value goods just don't work for major sales. Rackham went on to introduce his SPIN-selling method, where SPIN describes the whole selling process - Situation questions, Problem questions, Implication questions, Need-payoff questions. SPIN-selling provides you with a set of simple and practical techniques which have been tried in many of today's leading companies with dramatic improvements to their sales performance.

  8. Chiral higher spin gravity

    Science.gov (United States)

    Krishnan, Chethan; Raju, Avinash

    2017-06-01

    We construct a candidate for the most general chiral higher spin theory with AdS3 boundary conditions. In the Chern-Simons language, on the left it has the Drinfeld-Sokolov reduced form, but on the right all charges and chemical potentials are turned on. Altogether (for the spin-3 case) these are 19 functions. Despite this, we show that the resulting metric has the form of the "most general" AdS3 boundary conditions discussed by Grumiller and Riegler. The asymptotic symmetry algebra is a product of a W3 algebra on the left and an affine s l (3 )k current algebra on the right, as desired. The metric and higher spin fields depend on all the 19 functions. We compare our work with previous results in the literature.

  9. Spin Waves in Terbium

    DEFF Research Database (Denmark)

    Jensen, J.; Houmann, Jens Christian Gylden

    1975-01-01

    The selection rules for the linear couplings between magnons and phonons propagating in the c direction of a simple basal-plane hcp ferromagnet are determined by general symmetry considerations. The acoustic-optical magnon-phonon interactions observed in the heavy-rare-earth metals have been...... explained by Liu as originating from the mixing of the spin states of the conduction electrons due to the spin-orbit coupling. We find that this coupling mechanism introduces interactions which violate the selection rules for a simple ferromagnet. The interactions between the magnons and phonons propagating...... in the c direction of Tb have been studied experimentally by means of inelastic neutron scattering. The magnons are coupled to both the acoustic- and optical-transverse phonons. By studying the behavior of the acoustic-optical coupling, we conclude that it is a spin-mixed-induced coupling as proposed...

  10. Spin flexoelectricity and chiral spin structures in magnetic films

    OpenAIRE

    Pyatakov, A. P.; Sergeev, A. S.; Mikailzade, F. A.; Zvezdin, A. K.

    2015-01-01

    In this short review a broad range of chiral phenomena observed in magnetic films (spin cycloid and skyrmion structures formation as well as chirality dependent domain wall motion) is considered under the perspective of spin flexoelectricity, i.e. the relation between bending of magnetization pattern and electric polarization. The similarity and the difference between the spin flexoelectricity and the newly emerged notion of spin flexomagnetism is discussed. The phenomenological arguments bas...

  11. The occurrence and regional distribution of DR4 on herniated disc cells: a potential apoptosis pathway in lumbar intervertebral disc.

    Science.gov (United States)

    Zhang, Liang; Niu, Tao; Yang, Shang-You; Lu, Zhenhua; Chen, Bohua

    2008-02-15

    Intervertebral discs surgically obtained from 60 herniated patients and 5 normal individuals were examined to correlate the regional distribution of DR4-receptor and apoptosis. To explore the role of a tumor necrosis factor superfamily member DR4 and the TRAIL/DR4 mediated apoptosis in the human lumbar intervertebral disc. The pathogenesis of lumbar degenerative intervertebral discs remains not completely understood. In herniated lumbar disc tissues, increased apoptosis and higher expression of Fas/Fas ligand and caspase-3 have been reported, suggesting a pivotal role of apoptotic mechanisms in intervertebral disc degeneration. However, it is not clear that apoptosis mediators such as TRAIL and Death Receptor 4 (DR4), which often represent different apoptosis signal pathways, contribute to the apoptosis process during the development of the degenerated intervertebral discs. Apoptosis was determined by poly(ADP-ribose) polymerase (PARP) p85 immunohistochemistry. Expression of DR4 was revealed by immunohistochemistry analysis. Statistical difference among groups was analyzed using one-way ANOVA with LSD post hoc multiple comparisons and the bivariate correlations. Apoptotic cells were detected in the nucleus pulposus and anulus fibrosus of all samples. However, the number of apoptotic cells was significantly higher in the nucleus compared with the anulus. Further, there were significantly more apoptotic cells in the herniated discs compared with the normal discs. Within herniated discs, a remarkably higher percentage of positive staining cells were detected in the uncontained discs than the contained ones. Strong expression of DR4 was detected in all samples of degenerative herniated discs, whereasmuch weaker expression was sporadically identified in normal discs. In addition, the prevalence of apoptosis positively correlated with the severity of disc degeneration. The concomitant increase of DR4 expression in the regions of heavy apoptotic cell aggregation suggests

  12. Material Science in Cervical Total Disc Replacement.

    Science.gov (United States)

    Pham, Martin H; Mehta, Vivek A; Tuchman, Alexander; Hsieh, Patrick C

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation.

  13. Cervical disc arthroplasty: Pros and cons.

    Science.gov (United States)

    Moatz, Bradley; Tortolani, P Justin

    2012-01-01

    Cervical disc arthroplasty has emerged as a promising potential alternative to anterior cervical discectomy and fusion (ACDF) in appropriately selected patients. Despite a history of excellent outcomes after ACDF, the question as to whether a fusion leads to adjacent segment degeneration remains unanswered. Numerous US investigational device exemption trials comparing cervical arthroplasty to fusion have been conducted to answer this question. This study reviews the current research regarding cervical athroplasty, and emphasizes both the pros and cons of arthroplasty as compared with ACDF. Early clinical outcomes show that cervical arthroplasty is as effective as the standard ACDF. However, this new technology is also associated with an expanding list of novel complications. Although there is no definitive evidence that cervical disc replacement reduces the incidence of adjacent segment degeneration, it does show other advantages; for example, faster return to work, and reduced need for postoperative bracing.

  14. Material Science in Cervical Total Disc Replacement

    Science.gov (United States)

    Pham, Martin H.; Mehta, Vivek A.; Tuchman, Alexander; Hsieh, Patrick C.

    2015-01-01

    Current cervical total disc replacement (TDR) designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti), and cobalt-chrome (CoCr). These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation. PMID:26523281

  15. Material Science in Cervical Total Disc Replacement

    Directory of Open Access Journals (Sweden)

    Martin H. Pham

    2015-01-01

    Full Text Available Current cervical total disc replacement (TDR designs incorporate a variety of different biomaterials including polyethylene, stainless steel, titanium (Ti, and cobalt-chrome (CoCr. These materials are most important in their utilization as bearing surfaces which allow for articular motion at the disc space. Long-term biological effects of implanted materials include wear debris, host inflammatory immune reactions, and osteolysis resulting in implant failure. We review here the most common materials used in cervical TDR prosthetic devices, examine their bearing surfaces, describe the construction of the seven current cervical TDR devices that are approved for use in the United States, and discuss known adverse biological effects associated with long-term implantation of these materials. It is important to appreciate and understand the variety of biomaterials available in the design and construction of these prosthetics and the considerations which guide their implementation.

  16. MR imaging of degenerative disc disease

    Energy Technology Data Exchange (ETDEWEB)

    Farshad-Amacker, Nadja A., E-mail: nadja.farshad@usz.ch [Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich (Switzerland); Farshad, Mazda [Department of Orthopaedic Surgery, Balgrist University Hospital, Zurich (Switzerland); Winklehner, Anna; Andreisek, Gustav [Institute of Diagnostic and Interventional Radiology, University Hospital of Zurich, Zurich (Switzerland)

    2015-09-15

    Highlights: • This systematic literature review summarizes the current knowledge on MR imaging in degenerative disc disease. • Different classification systems for segmental spine degeneration are summarized. • It outlines the diagnostic limitations of MR imaging. - Abstract: Magnet resonance imaging (MRI) is the most commonly used imaging modality for diagnosis of degenerative disc disease (DDD). Lack of precise observations and documentation of aspects within the complex entity of DDD might partially be the cause of poor correlation of radiographic findings to clinical symptoms. This literature review summarizes the current knowledge on MRI in DDD and outlines the diagnostic limitations. The review further sensitizes the reader toward awareness of potentially untended aspects of DDD and the interaction of DDD and endplate changes. A summary of the available classifications for DDD is provided.

  17. Inflammation in intervertebral disc degeneration and regeneration

    Science.gov (United States)

    Molinos, Maria; Almeida, Catarina R.; Caldeira, Joana; Cunha, Carla; Gonçalves, Raquel M.; Barbosa, Mário A.

    2015-01-01

    Intervertebral disc (IVD) degeneration is one of the major causes of low back pain, a problem with a heavy economic burden, which has been increasing in prevalence as populations age. Deeper knowledge of the complex spatial and temporal orchestration of cellular interactions and extracellular matrix remodelling is critical to improve current IVD therapies, which have so far proved unsatisfactory. Inflammation has been correlated with degenerative disc disease but its role in discogenic pain and hernia regression remains controversial. The inflammatory response may be involved in the onset of disease, but it is also crucial in maintaining tissue homeostasis. Furthermore, if properly balanced it may contribute to tissue repair/regeneration as has already been demonstrated in other tissues. In this review, we focus on how inflammation has been associated with IVD degeneration by describing observational and in vitro studies as well as in vivo animal models. Finally, we provide an overview of IVD regenerative therapies that target key inflammatory players. PMID:25673296

  18. Spinning geodesic Witten diagrams

    International Nuclear Information System (INIS)

    Dyer, Ethan; Freedman, Daniel Z.; Massachusetts Institute of Technology; Massachusetts Institute of Technology; Sully, James; McGill University, Montreal, QC

    2017-01-01

    We present an expression for the four-point conformal blocks of symmetric traceless operators of arbitrary spin as an integral over a pair of geodesics in Anti-de Sitter space, generalizing the geodesic Witten diagram formalism of Hijano et al. to arbitrary spin. As an intermediate step in the derivation, we identify a convenient basis of bulk threepoint interaction vertices which give rise to all possible boundary three point structures. Lastly, we highlight a direct connection between the representation of the conformal block as geodesic Witten diagram and the shadow operator formalism.

  19. Spin gating electrical current

    Czech Academy of Sciences Publication Activity Database

    Ciccarelli, C.; Zarbo, Liviu; Irvine, A.C.; Campion, R. P.; Gallagher, B. L.; Wunderlich, Joerg; Jungwirth, Tomáš; Ferguson, A.J.

    2012-01-01

    Roč. 101, č. 12 (2012), , , "122411-1"-"122411-4" ISSN 0003-6951 R&D Projects: GA AV ČR KJB100100802; GA AV ČR KAN400100652 EU Projects: European Commission(XE) 268066 - 0MSPIN; European Commission(XE) 215368 - SemiSpinNet Grant - others:AV ČR(CZ) AP0801 Program:Akademická prémie - Praemium Academiae Institutional research plan: CEZ:AV0Z10100521 Keywords : ferromagnetic resonance * spin-orbit coupling * nanodevices Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.794, year: 2012 http://arxiv.org/abs/1203.2439

  20. Spin echo in synchrotrons

    Directory of Open Access Journals (Sweden)

    Alexander W. Chao

    2007-01-01

    Full Text Available As a polarized beam is accelerated through a depolarization resonance, its polarization is reduced by a well-defined calculable reduction factor. When the beam subsequently crosses a second resonance, the final beam polarization is considered to be reduced by the product of the two reduction factors corresponding to the two crossings, each calculated independently of the other. This is a good approximation when the spread of spin precession frequency Δν_{spin} of the beam (particularly due to its energy spread is sufficiently large that the spin precession phases of individual particles smear out completely during the time τ between the two crossings. This approximate picture, however, ignores two spin dynamics effects: an interference-overlap effect and a spin echo effect. This paper is to address these two effects. The interference-overlap effect occurs when Δν_{spin} is too small, or when τ is too short, to complete the smearing process. In this case, the two resonance crossings overlap each other, and the final polarization exhibits constructive or destructive interference patterns depending on the exact value of τ. Typically, the beam’s energy spread is large and this interference-overlap effect does not occur. To study this effect, therefore, it is necessary to reduce the beam energy spread and to consider two resonance crossings very close to each other. The other mechanism, also due to the interplay between two resonance crossings, is spin echo. It turns out that even when the precession phases appear to be completely smeared between the two crossings, there will still be a sudden and short-lived echo signal of beam polarization at a time τ after the second crossing; the magnitude of which can be as large as 57%. This echo signal exists even when the beam has a sizable energy spread and when τ is very large, and could be a sensitive (albeit challenging way to experimentally test the intricate spin dynamics in a synchrotron

  1. Spin, gravity, and inertia.

    Science.gov (United States)

    Obukhov, Y N

    2001-01-08

    The gravitational effects in the relativistic quantum mechanics are investigated. The exact Foldy-Wouthuysen transformation is constructed for the Dirac particle coupled to the static spacetime metric. As a direct application, we analyze the nonrelativistic limit of the theory. The new term describing the specific spin (gravitational moment) interaction effect is recovered in the Hamiltonian. The comparison of the true gravitational coupling with the purely inertial case demonstrates that the spin relativistic effects do not violate the equivalence principle for the Dirac fermions.

  2. Influence of degenerative changes of intervertebral disc

    Directory of Open Access Journals (Sweden)

    WANG Yi

    2012-04-01

    Full Text Available 【Abstract】Objective: To investigate the material properties of normal and degenerated intervertebral discs (IVDs and examine the effect of degenerative changes on IVD pathology. Methods: A computer-based online search was under-taken to identify English articles about material properties of IVDs published from January 1950 to 2011 in PubMed database. The retrieved keywords included material properties, intervertebral disc and degeneration. Based on the principles of reliability, advancement and efficiency, the obtained data were primarily examined, and the original source was retrieved to read the full-text. Repetitive articles were excluded. The data of material properties of normal and degenerated IVDs were summarized and analyzed by meta-analysis. Results: The data of Young's modulus, Poisson's ratio, shear modulus, hydraulic permeability and intradiscal pres-sure of normal and degenerated IVDs were obtained. Com-pared with normal IVDs, the Young's modulus and shear modulus of annulus fibrosus and nucleus pulposus were higher in degenerated IVDs, the Poisson's ratio was lower while the hydraulic permeability and intradiscal pressure were higher. Besides, the degeneration-related alterations in IVDs had an influence both on itself and other spinal structures, leading to diseases such as bulging disc, discogenic pain and spinal stenosis. Meanwhile, the heavy mechanical loading and injury indicated important pathways to IVD degeneration. Conclusions: To a certain extent, the degenerative changes of IVD influence its material properties. And the degeneration-related alterations of composition can cause structural failure of IVDs, leading to injuries and diseases. Key words: Intervertebral disc; Mechanical phenomena; Degeneration; Elastic modulus; Permeability; Pathology

  3. [Treatment of thoracic disc herniation. Case report].

    Science.gov (United States)

    Picado-Baca, Mauricio Leonardo; Mireles-Cano, José Nicolás; León-Meza, Víctor Manuel; García-González, Oscar Guillermo; Ramos-Trujillo, Alejandro

    2016-01-01

    Herniated thoracic intervertebral disc is a rare cause of spinal cord compression. Its frequency varies from 0.15% to 1.7% of all disc herniations, and produces symptoms in 0.5% to 0.8%. Case 1. A 50-year-old woman, with pain and burning sensation in left hemithorax of four months of onset. It was treated as a herpetic syndrome, with no improvement. She was seen after thirteen days of exacerbation of clinical symptoms. The physical examination showed asymmetric paraparesis, lower left pelvic limb 1/5, and right pelvic limb 3/5¸ sensory level T8, with left Babinski positive. A thoracic disc herniation in space T8-T9 was diagnosed. A 55-year-old patient with a history of presenting pain in lumbar area of 5 years onset. She also had radicular pain that radiated to the right pelvic limb, with intensity 10/10 on a Visual Analogue Scale. Her physical examination showed muscle strength 5/5, with normal sensitivity in all dermatomes and tendon reflexes, and a positive right Babinski. Thoracic disc herniation T7-T8 level was diagnosed. Due to anatomical conditions that define this type of hernia, the extracavitary posterolateral approach should be the recommended surgical procedure when the simultaneously performed anterior decompression and fixation with posterior instrumentation are the treatments proposed. Despite the different anatomical structures of this special area, it was possible to obtain satisfactory results for both clinical cases. Copyright © 2015 Academia Mexicana de Cirugía A.C. Publicado por Masson Doyma México S.A. All rights reserved.

  4. Development of Vibrating Disc Piezoelectric Gyroscope

    OpenAIRE

    A.K. Singh; U.K. Gorain

    2004-01-01

    The paper presents an indigenously developed vibrating disc piezoelectric gyroscope, in which both excitation and detection have been done through piezoelectric, using PZT-5H material. The gyroscope has been driven to resonant state by direct piezoelectric effect, using 20 V ac signal at 93 kHz, and the output has been detected by the reverse piezoelectric effect.The performance of this gyroscope has been tested with 3 microprocessor-controlled turntable, and the output of the gyroscope has b...

  5. Footprint mismatch in total cervical disc arthroplasty.

    Science.gov (United States)

    Thaler, Martin; Hartmann, Sebastian; Gstöttner, Michaela; Lechner, Ricarda; Gabl, Michael; Bach, Christian

    2013-04-01

    Cervical disc arthroplasty has become a commonplace surgery for the treatment of cervical radiculopathy and myelopathy. Most manufacturers derive their implant dimensions from early published cadaver studies. Ideal footprint match of the prosthesis is essential for good surgical outcome. We measured the dimensions of cervical vertebrae from computed tomography (CT) scans and to assess the accuracy of match achieved with the most common cervical disc prostheses [Bryan (Medtronic), Prestige LP (Medtronic), Discover (DePuy) Prodisc-C (Synthes)]. A total of 192 endplates in 24 patients (56.3 years) were assessed. The anterior-posterior and mediolateral diameters of the superior and inferior endplates were measured with a digital measuring system. Overall, 53.5 % of the largest device footprints were smaller in the anterior-posterior diameter and 51.1 % in the mediolateral diameter were smaller than cervical endplate diameters. For levels C5/C6 and C6/C7 an inappropriate size match was noted in 61.9 % as calculated from the anteroposterior diameter. Mismatch at the center mediolateral diameter was noted in 56.8 %. Of the endplates in the current study up to 58.1 % of C5/C6 and C6/C7, and up to 45.3 % of C3/C4 and C4/C5 were larger than the most frequently implanted cervical disc devices. Surgeons and manufacturers should be aware of the size mismatch in currently available cervical disc prostheses, which may endanger the safety and efficacy of the procedure. Undersizing the prosthetic device may lead to subsidence, loosening, heterotopic ossification and biomechanical failure caused by an incorrect center of rotation and load distribution, affecting the facet joints.

  6. Risk Factors for Recurrent Lumbar Disc Herniation

    Science.gov (United States)

    Huang, Weimin; Han, Zhiwei; Liu, Jiang; Yu, Lili; Yu, Xiuchun

    2016-01-01

    Abstract Recurrent lumbar disc herniation (rLDH) is a common complication following primary discectomy. This systematic review aimed to investigate the current evidence on risk factors for rLDH. Cohort or case-control studies addressing risk factors for rLDH were identified by search in Pubmed (Medline), Embase, Web of Science, and Cochrane library from inception to June 2015. Relevant results were pooled to give overall estimates if possible. Heterogeneity among studies was examined and publication bias was also assessed. A total of 17 studies were included in this systematic review. Risk factors that had significant relation with rLDH were smoking (OR 1.99, 95% CI 1.53–2.58), disc protrusion (OR 1.79, 95% CI 1.15–2.79), and diabetes (OR 1.19, 95% CI 1.06–1.32). Gender, BMI, occupational work, level, and side of herniation did not correlate with rLDH significantly. Based on current evidence, smoking, disc protrusion, and diabetes were predictors for rLDH. Patients with these risk factors should be paid more attention for prevention of recurrence after primary surgery. More evidence provided by high-quality observational studies is still needed to further investigate risk factors for rLDH. PMID:26765413

  7. Chipping machines: disc and drum energy requirements

    Directory of Open Access Journals (Sweden)

    Alessio Facello

    2013-09-01

    Full Text Available Air pollution and fossil fuel reserves exhaustion are increasing the importance of the biomass-derived products, in particular wood, as source of clean and renewable energy for the production of electricity or steam. In order to improve the global efficiency and the entire production chain, we have to evaluate the energetic aspects linked to the process of transformation, handling and transport of these materials. This paper reports results on a comparison between two chippers of similar size using different cutting technology: disc and drum tool respectively. During trials, fuel consumption, PTO torque and speed, processing time and weight of processed material were recorded. Power demand, fuel consumption, specific energy and productivity were computed. The machine was fed with four different feedstock types (chestnut logs, poplar logs, poplar branches, poplar sawmill residues. 15 repetitions for each combination of feedstock-tool were carried out. The results of this study show that the disc tool requires, depending on the processed material, from 12 to 18% less fuel per unit of material processed than the drum tool, and consequently, from 12 to 16% less specific energy. In particular, the highest difference between tools was found in branches processing whereas the smallest was in poplar logs. Furthermore the results of the investigation indicate, that, in testing conditions, the productivity of drum tool is higher (8% than disc tool.

  8. Hypokalemia mimicking a herniated vertebral disc.

    Science.gov (United States)

    Delhey, Patrick Roman; Holzapfel, Boris Michael; Kanz, Karl-Georg; Mayer-Wagner, Susanne

    2015-06-01

    A herniated vertebral disc is a common cause of paralysis. Other causes include infections, tumors, and neurologic diseases. A rare and dangerous but in most cases easily treatable cause is hypokalemia. Clinically, the acute symptoms may resemble a herniated vertebral disc, but hypokalemia per se is life-threatening by causing heart arrest through ventricular tachycardia or fibrillation. A patient with back pain and neurologic deficit in the lower extremities after a history of a herniated vertebral disc presented, who finally receives the diagnosis of hypokalemia. Case report. A 25-year-old female patient presenting after a fall with muscle weakness in both legs was followed clinically and radiographically. Neurological examination showed a lower extremity muscle weakness with three-fifths muscular strength of the quadriceps and tibialis anterior muscle on both sides. Reflexes were diminished bilaterally, anal sphincter tone was normal. Plain radiography suggested a posterior rim fracture of L5, but computed tomography did not confirm this diagnosis. The laboratory investigation revealed a hypokalemia of 1.7 mEq/L. On electrolyte replacement, the patient recovered immediately. This report describes a misleading diagnostic case of back pain and neurologic deficit after a trauma and sensitizes for the possible life-threatening diagnosis hypokalemia, which is rare but easily treatable. Copyright © 2015 Elsevier Inc. All rights reserved.

  9. Human umbilical cord derivatives regenerate intervertebral disc.

    Science.gov (United States)

    Beeravolu, Naimisha; Brougham, Jared; Khan, Irfan; McKee, Christina; Perez-Cruet, Mick; Chaudhry, G Rasul

    2016-09-30

    Intervertebral disc (IVD) degeneration is characterized by the loss of nucleus pulposus (NP), which is a common cause for lower back pain. Although, currently, there is no cure for the degenerative disc disease, stem cell therapy is increasingly being considered for its treatment. In this study, we investigated the feasibility and efficacy of human umbilical cord mesenchymal stem cells (MSCs) and chondroprogenitor cells (CPCs) derived from those cells to regenerate damaged IVD in a rabbit model. Transplanted cells survived, engrafted and dispersed into NP in situ. Significant improvement in the histology, cellularity, extracellular matrix proteins, and water and glycosaminoglycan contents in IVD recipients of CPCs was observed compared to MSCs. In addition, IVDs receiving CPCs exhibited higher expression of NP-specific human markers, SOX9, aggrecan, collagen 2, FOXF1 and KRT19. The novelty of the study is that in vitro differentiated CPCs derived from umbilical cord MSCs, demonstrated far greater capacity to regenerate damaged IVDs, which provides basis and impetus for stem cell based clinical studies to treat degenerative disc disease. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

  10. Dynamic analysis of three autoventilated disc brakes

    Directory of Open Access Journals (Sweden)

    Ricardo A. García-León

    2017-09-01

    Full Text Available The braking system of a car must meet several requirements, among which safety is the most important. It is also composed of a set of mechanical parts such as springs, different types of materials (Metallic and Non Metallic, gases and liquids. The brakes must work safely and predictably in all circumstances, which means having a stable level of friction, in any condition of temperature, humidity and salinity of the environment. For a correct design and operation of brake discs, it is necessary to consider different aspects, such as geometry, type of material, mechanical strength, maximum temperature, thermal deformation, cracking resistance, among others. Therefore, the main objective of this work is to analyze the dynamics and kinetics of the brake system from the pedal as the beginning of mathematical calculations to simulate the behavior and Analysis of Finite Elements (FEA, with the help of SolidWorks Simulation Software. The results show that the third brake disc works best in relation to the other two discs in their different working conditions such as speed and displacement in braking, concluding that depending on the geometry of the brake and the cooling channels these systems can be optimized that are of great importance for the automotive industry.

  11. A stochastic picture of spin

    International Nuclear Information System (INIS)

    Faris, W.G.

    1981-01-01

    Dankel has shown how to incorporate spin into stochastic mechanics. The resulting non-local hidden variable theory gives an appealing picture of spin correlation experiments in which Bell's inequality is violated. (orig.)

  12. Pressão de aplicação com pulverizador de barra e eficiência de bioinseticidas fúngicos comerciais Application pressure in boom sprayer and efficiency of commercial fungal bioinsecticides

    Directory of Open Access Journals (Sweden)

    Cesar de Oliveira Guimarães

    2004-12-01

    Full Text Available Bioinseticidas fúngicos são aplicados com pulverizadores convencionais e algumas características destes equipamentos podem não ser adequadas e afetar a eficiência dos bioinseticidas. O objetivo deste trabalho foi verificar se pressões usuais, em aplicações com o pulverizador de barra, podem afetar a ação inseticida de conídios de Beauveria bassiana e Metarhizium anisopliae, componentes de produtos comerciais brasileiros. Para isso, suspensões aquosas de três bioinseticidas foram submetidas à passagem pelo equipamento em três pressões (20, 40 e 60 lbf pol-2 e avaliadas quanto ao rompimento, à viabilidade e à virulência dos conídios. Avaliou-se a viabilidade em lâminas de microscopia cobertas com meio de cultura, após incubação a 26±0,5ºC e fotoperíodo de 12 horas. A concentração foi determinada por meio de contagens em câmara de Neubauer e a virulência foi avaliada para lagartas de Diatraea saccharalis. Não foram encontradas, nos três produtos, influências significativas em nenhum dos parâmetros. Nas pressões avaliadas, a aplicação com o pulverizador de barra não reduz a viabilidade e nem a virulência dos conídios dos bioinseticidas testados, tampouco provoca destruição dos conídios.Fungal biopesticides are applied with conventional sprayers and this equipment may be inappropriate, and therefore affect field control efficacy of biopesticides. The objective of this research was to find out if the usual pressures used in the boom sprayers can affect the conidia pesticide activity of the Brazilian commercial entomopathogenic fungi Beauveria bassiana and Metarhizium anisopliae. Water fungi suspensions were passed through the equipment under three pressures (20, 40 and 60 psi and evaluated for viability, virulence and conidia disruption. The viability was evaluated in slides covered by culture media after incubation at 26±0.5ºC and 12 hours photophase. The concentration was determined through Neubauer

  13. Antiferromagnetic spin-orbitronics

    KAUST Repository

    Manchon, Aurelien

    2015-05-01

    Antiferromagnets have long remained an intriguing and exotic state of matter, whose application has been restricted to enabling interfacial exchange bias in metallic and tunneling spin-valves [1]. Their role in the expanding field of applied spintronics has been mostly passive and the in-depth investigation of their basic properties mostly considered from a fundamental perspective.

  14. " The Story of Spin

    Indian Academy of Sciences (India)

    Home; Journals; Resonance – Journal of Science Education; Volume 3; Issue 11. The Story of Spin - From Spectroscopy to Relativistic Quantum Mechanics. N Mukunda. Book Review Volume 3 Issue 11 November 1998 pp 89-90. Fulltext. Click here to view fulltext PDF. Permanent link:

  15. Spin and isospin modes

    International Nuclear Information System (INIS)

    Suzuki, T.; Sagawa, H.

    2000-01-01

    Complete text of publication follows. Spin and isospin modes in nuclei are investigated. We discuss some of the following topics. 1. Spin-dipole excitations in 12 C and 16 O are studied (1). Effects of tensor and spin-orbit interactions on the distribution of the strengths are investigated, and neutral current neutrino scattering cross sections in 16 O are obtained for heavy-flavor neutrinos from the supernovae. 2. Gamow-Teller (GT) and spin-dipole (SD) modes in 208 Bi are investigated. Quenching and fragmentation of the GT strength are discussed (2). SD excitations and electric dipole (E1) transitions between the GT and SD states are studied (3). Calculated E1 strengths are compared with the sum rule values obtained within the 1p-1h and 1p-1h + 2p-2h configuration spaces. 3. Coulomb displacement energy (CDE) of the IAS of 14 Be is calculated, and the effects of the halo on the CDE and the configuration of the halo state are investigated. 4. Spreading width of IAS and isospin dependence of the width are investigated (4). Our formula for the width explains very well the observed isospin dependence (5). (author)

  16. On "spinning" membrane models

    NARCIS (Netherlands)

    Bergshoeff, E.; Sezgin, E.; Townsend, P.K.

    1988-01-01

    Several alternative actions for a bosonic membrane have recently been proposed. We show that a linearly realized locally world-volume-supersymmetric (spinning membrane) extension of any of these actions implies an analogous extension of the standard Dirac membrane action. We further show that a

  17. Nuclear spin-off

    International Nuclear Information System (INIS)

    1981-11-01

    This booklet gives examples of 'nuclear spin off', from research programmes carried out for the UKAEA, under the following headings; non destructive testing; tribology; environmental protection; flow measurement; material sciences; mechanical engineering; marine services; biochemical technology; electronic instrumentation. (U.K.)

  18. The invariance of spin

    International Nuclear Information System (INIS)

    Bramson, B.D.

    1978-01-01

    An isolated system in general relativity makes a transition between stationary states. It is shown that the spin vectors of the system, long before and long after the emission of radiation, are supertranslation invariant and, hence, independent of the choice of Minkowski observation space. (author)

  19. Spin Injection in Indium Arsenide

    Directory of Open Access Journals (Sweden)

    Mark eJohnson

    2015-08-01

    Full Text Available In a two dimensional electron system (2DES, coherent spin precession of a ballistic spin polarized current, controlled by the Rashba spin orbit interaction, is a remarkable phenomenon that’s been observed only recently. Datta and Das predicted this precession would manifest as an oscillation in the source-drain conductance of the channel in a spin-injected field effect transistor (Spin FET. The indium arsenide single quantum well materials system has proven to be ideal for experimental confirmation. The 2DES carriers have high mobility, low sheet resistance, and high spin orbit interaction. Techniques for electrical injection and detection of spin polarized carriers were developed over the last two decades. Adapting the proposed Spin FET to the Johnson-Silsbee nonlocal geometry was a key to the first experimental demonstration of gate voltage controlled coherent spin precession. More recently, a new technique measured the oscillation as a function of channel length. This article gives an overview of the experimental phenomenology of the spin injection technique. We then review details of the application of the technique to InAs single quantum well (SQW devices. The effective magnetic field associated with Rashba spin-orbit coupling is described, and a heuristic model of coherent spin precession is presented. The two successful empirical demonstrations of the Datta Das conductance oscillation are then described and discussed.

  20. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    Spin tunnelling; spin path integrals; discrete phase integral method; diabolical points. ... technologies. Our purpose in this article is rather different. The molecular systems have total spin of the order of 10, and magnetocrystalline anisotropies of few tens of Kelvin ...... The point С' is of this new type, and here it may be said to.

  1. Spin transport in graphene nanostructures

    NARCIS (Netherlands)

    Guimaraes, M. H. D.; van den Berg, J. J.; Vera-Marun, I. J.; Zomer, P. J.; van Wees, B. J.

    2014-01-01

    Graphene is an interesting material for spintronics, showing long spin relaxation lengths even at room temperature. For future spintronic devices it is important to understand the behavior of the spins and the limitations for spin transport in structures where the dimensions are smaller than the

  2. Spin Transport in Bose Gases

    NARCIS (Netherlands)

    van Driel, H.J.

    2012-01-01

    In this Thesis, we show that in a rotating two-component Bose mixture, the spin drag between the two different spin species shows a Hall effect. This spin drag Hall effect can be observed experimentally by studying the out-of-phase dipole mode of the mixture. We determine the damping of this mode

  3. Spin Transport in Semiconductor heterostructures

    International Nuclear Information System (INIS)

    Marinescu, Domnita Catalina

    2011-01-01

    The focus of the research performed under this grant has been the investigation of spin transport in magnetic semiconductor heterostructures. The interest in these systems is motivated both by their intriguing physical properties, as the physical embodiment of a spin-polarized Fermi liquid, as well as by their potential applications as spintronics devices. In our work we have analyzed several different problems that affect the spin dynamics in single and bi-layer spin-polarized two-dimensional (2D) systems. The topics of interests ranged from the fundamental aspects of the electron-electron interactions, to collective spin and charge density excitations and spin transport in the presence of the spin-orbit coupling. The common denominator of these subjects is the impact at the macroscopic scale of the spin-dependent electron-electron interaction, which plays a much more subtle role than in unpolarized electron systems. Our calculations of several measurable parameters, such as the excitation frequencies of magneto-plasma modes, the spin mass, and the spin transresistivity, propose realistic theoretical estimates of the opposite-spin many-body effects, in particular opposite-spin correlations, that can be directly connected with experimental measurements.

  4. Spinning Them Off: Entrepreneuring Practices in Corporate Spin-Offs

    Directory of Open Access Journals (Sweden)

    Katja Maria Hydle

    2016-01-01

    Full Text Available This paper focuses on the practices between parent and child firms in corporate spinoffs. We uncover the enacted aspects of knowledge, called knowing, through theories from seven cases of incumbent-backed spin-offs and find that the management of the parent firms are highly involved in the spin-offs. The practices associated with spinning off are solving problems, involving multidisciplinary expertise and entrepreneuring management at the parent firm. We contribute to the spin-off literature by discussing the knowledge required for successfully spinning off child firms and to practice theory by empirically uncovering the practical understanding involved in the origin and perpetuation of an organization.

  5. Spin flexoelectricity and chiral spin structures in magnetic films

    Science.gov (United States)

    Pyatakov, A. P.; Sergeev, A. S.; Mikailzade, F. A.; Zvezdin, A. K.

    2015-06-01

    In this short review a broad range of chiral phenomena observed in magnetic films (spin cycloid and skyrmion structures formation as well as chirality dependent domain wall motion) is considered under the perspective of spin flexoelectricity, i.e. the relation between bending of magnetization pattern and electric polarization. The similarity and the difference between the spin flexoelectricity and the newly emerged notion of spin flexomagnetism are discussed. The phenomenological arguments based on the geometrical idea of curvature-induced effects are supported by analysis of the microscopic mechanisms of spin flexoelectricity based on three-site ion indirect exchange and twisted RKKY interaction models.

  6. Total disc replacement using tissue-engineered intervertebral discs in the canine cervical spine.

    Directory of Open Access Journals (Sweden)

    Yu Moriguchi

    Full Text Available The most common reason that adults in the United States see their physician is lower back or neck pain secondary to degenerative disc disease. To date, approaches to treat degenerative disc disease are confined to purely mechanical devices designed to either eliminate or enable flexibility of the diseased motion segment. Tissue engineered intervertebral discs (TE-IVDs have been proposed as an alternative approach and have shown promise in replacing native IVD in the rodent tail spine. Here we demonstrate the efficacy of our TE-IVDs in the canine cervical spine. TE-IVD components were constructed using adult canine annulus fibrosis and nucleus pulposus cells seeded into collagen and alginate hydrogels, respectively. Seeded gels were formed into a single disc unit using molds designed from the geometry of the canine spine. Skeletally mature beagles underwent discectomy with whole IVD resection at levels between C3/4 and C6/7, and were then divided into two groups that received only discectomy or discectomy followed by implantation of TE-IVD. Stably implanted TE-IVDs demonstrated significant retention of disc height and physiological hydration compared to discectomy control. Both 4-week and 16-week histological assessments demonstrated chondrocytic cells surrounded by proteoglycan-rich matrices in the NP and by fibrocartilaginous matrices in the AF portions of implanted TE-IVDs. Integration into host tissue was confirmed over 16 weeks without any signs of immune reaction. Despite the significant biomechanical demands of the beagle cervical spine, our stably implanted TE-IVDs maintained their position, structure and hydration as well as disc height over 16 weeks in vivo.

  7. The life cycles of Be viscous decretion discs: fundamental disc parameters of 54 SMC Be stars

    Science.gov (United States)

    Rímulo, L. R.; Carciofi, A. C.; Vieira, R. G.; Rivinius, Th; Faes, D. M.; Figueiredo, A. L.; Bjorkman, J. E.; Georgy, C.; Ghoreyshi, M. R.; Soszyński, I.

    2018-02-01

    Be stars are main-sequence massive stars with emission features in their spectrum, which originates in circumstellar gaseous discs. Even though the viscous decretion disc (VDD) model can satisfactorily explain most observations, two important physical ingredients, namely the magnitude of the viscosity (α) and the disk mass injection rate, remain poorly constrained. The light curves of Be stars that undergo events of disc formation and dissipation offer an opportunity to constrain these quantities. A pipeline was developed to model these events that uses a grid of synthetic light curves, computed from coupled hydrodynamic and radiative transfer calculations. A sample of 54 Be stars from the OGLE survey of the Small Magellanic Cloud (SMC) was selected for this study. Because of the way our sample was selected (bright stars with clear disc events), it likely represents the densest discs in the SMC. Like their siblings in the Galaxy, the mass of the disc in the SMC increases with the stellar mass. The typical mass and angular momentum loss rates associated with the disk events are of the order of ˜10-10 M⊙ yr-1 and ˜5 × 1036 g cm2 s-2, respectively. The values of α found in this work are typically of a few tenths, consistent with recent results in the literature and with the ones found in dwarf novae, but larger than current theory predicts. Considering the sample as a whole, the viscosity parameter is roughly two times larger at build-up (⟨αbu⟩ = 0.63) than at dissipation (⟨αd⟩ = 0.26). Further work is necessary to verify whether this trend is real or a result of some of the model assumptions.

  8. Schrödinger evolution of self-gravitating discs

    Science.gov (United States)

    Batygin, Konstantin

    2018-04-01

    An understanding of the long-term evolution of self-gravitating discs ranks among the classic outstanding problems of astrophysics. In this work, we show that the secular inclination dynamics of a geometrically thin quasi-Keplerian disc, with a surface density profile that scales as the inverse square-root of the orbital radius, are described by the time-dependent Schrödinger equation. Within the context of this formalism, nodal bending waves correspond to the eigenmodes of a quasi-particle's wavefunction, confined in an infinite square well with boundaries given by the radial extent of the disc. We further show that external secular perturbations upon self-gravitating discs exhibit a mathematical similarity to quantum scattering theory. Employing this framework, we derive an analytic criterion for the gravitational rigidity of a nearly-Keplerian disc under external perturbations. Applications of the theory to circumstellar discs and Galactic nuclei are discussed.

  9. Excitation of coherent propagating spin waves by pure spin currents.

    Science.gov (United States)

    Demidov, Vladislav E; Urazhdin, Sergei; Liu, Ronghua; Divinskiy, Boris; Telegin, Andrey; Demokritov, Sergej O

    2016-01-28

    Utilization of pure spin currents not accompanied by the flow of electrical charge provides unprecedented opportunities for the emerging technologies based on the electron's spin degree of freedom, such as spintronics and magnonics. It was recently shown that pure spin currents can be used to excite coherent magnetization dynamics in magnetic nanostructures. However, because of the intrinsic nonlinear self-localization effects, magnetic auto-oscillations in the demonstrated devices were spatially confined, preventing their applications as sources of propagating spin waves in magnonic circuits using these waves as signal carriers. Here, we experimentally demonstrate efficient excitation and directional propagation of coherent spin waves generated by pure spin current. We show that this can be achieved by using the nonlocal spin injection mechanism, which enables flexible design of magnetic nanosystems and allows one to efficiently control their dynamic characteristics.

  10. Spin-wave-induced spin torque in Rashba ferromagnets

    Science.gov (United States)

    Umetsu, Nobuyuki; Miura, Daisuke; Sakuma, Akimasa

    2015-05-01

    We study the effects of Rashba spin-orbit coupling on the spin torque induced by spin waves, which are the plane-wave dynamics of magnetization. The spin torque is derived from linear-response theory, and we calculate the dynamic spin torque by considering the impurity-ladder-sum vertex corrections. This dynamic spin torque is divided into three terms: a damping term, a distortion term, and a correction term for the equation of motion. The distorting torque describes a phenomenon unique to the Rashba spin-orbit coupling system, where the distorted motion of magnetization precession is subjected to the anisotropic force from the Rashba coupling. The oscillation mode of the precession exhibits an elliptical trajectory, and the ellipticity depends on the strength of the nesting effects, which could be reduced by decreasing the electron lifetime.

  11. Suspected herniated lumbar disc - computed tomography in differential diagnosis of non-disc-related sciatica

    Energy Technology Data Exchange (ETDEWEB)

    Weiss, T.; Koehler, D.; Treisch, J.; Claussen, C.; Felix, R.

    1984-07-01

    The most common reason a patient is referred for spinal CT examination is to exclude a ruptured intervertebral disc. Besides nerve root entrapment due to herniated disc, a number of unusual or unexpected conditions have been encountered in the course of CT lumbar spine studies. These include spondylolisthesis, spinal dysraphism, Paget's disease, and inflammatory, neoplastic, or metastatic lesions. The application of spinal (small-circle) target imaging includes the risk of overlooking soft tissue lesions that extend beyond the reconstruction circle. Therefore, complete (large-circle) circumferential abdominal scanning is recommended in case of a suspected extraspinal cause of sciatica.

  12. A method for quantitative measurement of lumbar intervertebral disc structures

    DEFF Research Database (Denmark)

    Tunset, Andreas; Kjær, Per; Samir Chreiteh, Shadi

    2013-01-01

    There is a shortage of agreement studies relevant for measuring changes over time in lumbar intervertebral disc structures. The objectives of this study were: 1) to develop a method for measurement of intervertebral disc height, anterior and posterior disc material and dural sac diameter using MRI......, 2) to evaluate intra- and inter-rater agreement and reliability for the measurements included, and 3) to identify factors compromising agreement....

  13. Thoracic spine disc-related abnormalities: longitudinal MR imaging assessment

    Energy Technology Data Exchange (ETDEWEB)

    Girard, Charles J.; Schweitzer, Mark E.; Morrison, William B.; Parellada, Joan A. [TJUH Radiology, Philadelphia, Pennsylvania (United States); Carrino, J.A. [Department of Radiology ASB-1, Harvard Medical School, Brigham and Women' s Hospital, L1, Room 002B, 75 Francis Street, MA 02115, Boston (United States)

    2004-04-01

    To describe and characterize the temporal changes in disc-related disorders of the thoracic spine using MR imaging. A retrospective longitudinal cohort study was carried out of 40 patients with two sequential thoracic spine MR images at variable intervals. The images were assessed for baseline presence of, new incidence of and changes in disc herniation, degenerative disc disease, endplate marrow signal alteration and Schmorl nodes. The range of follow-up was 4-149 weeks. Baseline presence was: disc herniation, 10% (49/480); degenerative disc disease, 14% (66/480); endplate marrow signal alteration, 2.3% (11/480); Schmorl nodes 9.6% (46/480). Most pre-existing lesions tended to remain unchanged. Herniations showed the most change, tending to improve in 27%. New incidence was: disc herniation, 1.5% (7/480), degenerative disc disease, 2% (10/480); endplate marrow signal alteration, 1.6% (8/480); Schmorl nodes, 2.1% (10/480). Disc degeneration was first visible at an 11-week interval and once established almost never changed over many weeks to months. Endplate signal alterations (Modic changes) were uncommon. Schmorl nodes show no change from baseline for up to 2 1/2 years. All findings predominated in the lower intervertebral levels from T6 to T10. The most prevalent thoracic spine disc-related findings are degeneration and herniation. Disc herniations predominate in the lower segments and are a dynamic phenomenon. Disc degeneration can be rapidly evolving but tends to remain unchanged after occurrence. Endplate marrow signal changes were an uncommon manifestation of thoracic disc disease. Schmorl nodes showed the least change over time. (orig.)

  14. Spontaneous resolution of a herniated fragment cervical disc

    OpenAIRE

    METE, Mesut; SAVRAN, Mehmet; DEMİRÇİVİ ÖZER, Füsun; DURANSOY, Yusuf Kurtuluş

    2012-01-01

    ABSTRACT Although the spontaneous resolution of herniated nucleus pulposus is a well known phe¬nomenon in lumbar disc herniations, it is rarely encountered in the cervical region. The spontaneous resolution of a herniated cervical disc in a woman is reported to describe a rare occurrence of spontaneous regression of a cervical herniated nucleus pulposus and to discuss its mechanism. A woman with a large and fragment herniated cervical disc refused to undergo operation and was followed-up ...

  15. Glaucomatous-Type Optic Discs in High Myopia.

    Directory of Open Access Journals (Sweden)

    Natsuko Nagaoka

    Full Text Available To assess the prevalence of glaucoma in patients with high myopia defined as myopic refractive error of >-8 diopters or axial length ≥26.5 mm.The hospital-based observational study included 172 patients (336 eyes with a mean age of 61.9±12.3 years and mean axial length of 30.1±2.3 mm (range: 24.7-39.1mm. Glaucomatous-type optic discs were defined by glaucomatous optic disc appearance. Glaucoma was defined by glaucomatous optic disc appearance and glaucomatous Goldmann visual field defects not corresponding with myopic macular changes.Larger disc area (mean: 3.18±1.94 mm2 was associated with longer axial length (P3.79 mm2 than in normal-sized discs or small discs (<1.51 mm2 after adjusting for older age. Axial length was not significantly (P = 0.38 associated with glaucoma prevalence in that model. Glaucoma prevalence increased by a factor of 1.39 for each increase in optic disc area by one mm2. Again, axial length was not significantly (P = 0.38 associated with glaucoma prevalence when added to this multivariate model.Within highly myopic individuals, glaucoma prevalence increased with larger optic disc size beyond a disc area of 3.8 mm2. Highly myopic megalodiscs as compared to normal sized discs or small discs had a 3.2 times higher risk for glaucomatous optic nerve neuropathy. The increased glaucoma prevalence in axial high myopia was primarily associated with axial myopia associated disc enlargement and not with axial elongation itself.

  16. New Brown Dwarf Discs in Upper Scorpius Observed with WISE

    Science.gov (United States)

    Dawson, P.; Scholz, A.; Ray, T. P.; Natta, A.; Marsh, K. A.; Padgett, D.; Ressler, M. E.

    2013-01-01

    We present a census of the disc population for UKIDSS selected brown dwarfs in the 5-10 Myr old Upper Scorpius OB association. For 116 objects originally identified in UKIDSS, the majority of them not studied in previous publications, we obtain photometry from the Wide-Field Infrared Survey Explorer data base. The resulting colour magnitude and colour colour plots clearly show two separate populations of objects, interpreted as brown dwarfs with discs (class II) and without discs (class III). We identify 27 class II brown dwarfs, 14 of them not previously known. This disc fraction (27 out of 116, or 23%) among brown dwarfs was found to be similar to results for K/M stars in Upper Scorpius, suggesting that the lifetimes of discs are independent of the mass of the central object for low-mass stars and brown dwarfs. 5 out of 27 discs (19 per cent) lack excess at 3.4 and 4.6 microns and are potential transition discs (i.e. are in transition from class II to class III). The transition disc fraction is comparable to low-mass stars.We estimate that the time-scale for a typical transition from class II to class III is less than 0.4 Myr for brown dwarfs. These results suggest that the evolution of brown dwarf discs mirrors the behaviour of discs around low-mass stars, with disc lifetimes of the order of 5 10 Myr and a disc clearing time-scale significantly shorter than 1 Myr.

  17. Magnetic Resonance Imaging in the Diagnostics of Spinal Disc Herniations

    OpenAIRE

    Katsiaryna, A.; Dmitry, A.

    2015-01-01

    BACKGROUND Currently the preoperative detection of degenerative disc diseases does not always correlate with neurological symptoms and present status of a patient. This paper outlines the possibilities of using magnetic resonance imaging in evaluation of thethe grade of severity of intervertebral disc herniations. METHODS A total 20 patients of the disc herniations with age group between 20 to 81 y were diagnosed and studied on «Avanta» highfield Magnetic Resonance Imaging machine by «Siemens...

  18. Spontaneous Regression of Intervertebral Disc Herniation – Case Reports

    OpenAIRE

    Rapan, Saša; Gulan, Gordan; Lovrić, Ivan; Jovanović, Savo

    2011-01-01

    Lumbar disc hernia (LDH) is a common cause of low back pain and radicular leg pain. It is well known that the majority of LDH patients recover spontaneously. Since the advent of MRI, a spontaneous regression of fragment size of disc hernia occurs, as well as mitigation of subjective difficulties and neurological disorders. Therefore, surgical treatment is not always method of choice in this disease. Two cases of conservatively treated large disc extrusion which result in significant ...

  19. Fenomena Komunikasi Female Disc Jockey di Kota Pekanbaru

    OpenAIRE

    Febriasistari, Atika Hersa; Wirman, Welly

    2016-01-01

    Female Disc Jockey becomes a phenomenon that thriving nowadays. Female Disc Jockey comes from different circle such student and even housewife. Until now the phenomenon of Female Disc Jockey is getting more develop marked by increasing the number of their performance on many event such night club in Pekanbaru. On their performance they often wearing sexy clothes. Meanwhile their work place is close to some kind of negative such alcohol, drugs, freesex and led to a negative stigma from many pe...

  20. Spin Structures in Magnetic Nanoparticles

    DEFF Research Database (Denmark)

    Mørup, Steen; Brok, Erik; Frandsen, Cathrine

    2013-01-01

    Spin structures in nanoparticles of ferrimagnetic materials may deviate locally in a nontrivial way from ideal collinear spin structures. For instance, magnetic frustration due to the reduced numbers of magnetic neighbors at the particle surface or around defects in the interior can lead to spin...... canting and hence a reduced magnetization. Moreover, relaxation between almost degenerate canted spin states can lead to anomalous temperature dependences of the magnetization at low temperatures. In ensembles of nanoparticles, interparticle exchange interactions can also result in spin reorientation...

  1. Apparent quasar disc sizes in the "bird's nest" paradigm

    Science.gov (United States)

    Abolmasov, P.

    2017-04-01

    Context. Quasar microlensing effects make it possible to measure the accretion disc sizes around distant supermassive black holes that are still well beyond the spatial resolution of contemporary instrumentation. The sizes measured with this technique appear inconsistent with the standard accretion disc model. Not only are the measured accretion disc sizes larger, but their dependence on wavelength is in most cases completely different from the predictions of the standard model. Aims: We suggest that these discrepancies may arise not from non-standard accretion disc structure or systematic errors, as it was proposed before, but rather from scattering and reprocession of the radiation of the disc. In particular, the matter falling from the gaseous torus and presumably feeding the accretion disc may at certain distances become ionized and produce an extended halo that is free from colour gradients. Methods: A simple analytical model is proposed assuming that a geometrically thick translucent inflow acts as a scattering mirror changing the apparent spatial properties of the disc. This inflow may be also identified with the broad line region or its inner parts. Results: Such a model is able to explain the basic properties of the apparent disc sizes, primarily their large values and their shallow dependence on wavelength. The only condition required is to scatter a significant portion of the luminosity of the disc. This can easily be fulfilled if the scattering inflow has a large geometrical thickness and clumpy structure.

  2. Surface image of herniated disc on three-dimensional CT

    Energy Technology Data Exchange (ETDEWEB)

    Chung, Kyung Il; Jeon, Chang Hoon; Kim, Sun Yong; Kim, Ok Hwa; Suh, Jung Ho [Ajou Univ. College of Medicine, Suwon(Korea, Republic of)

    1996-03-01

    To evaluate surface configuration of herniated disc on three-dimensional CT. Three dimensional surface images reconstructed from CT scans(1 mm thick) of 24 surgically confirmed herniated discs in 23 patients were reviewed. Disc surface was classified into peripheral and central zones in contact with consecutive peripheral ring and central endplate. Surface irregularity was categorized into two types(local and general). The incidence, size, and extent of local irregularity were observed. General irregularity incidence and severity ranges in 4 grades, and peripheral width were evaluated. The findings were correlated with discography. Local irregularity compatible with anulus tear in discography was shown in all. It was large(13/24) and mainly peripheral tract extending to disc margin in protrusion(3/5) and sequestration(5/7), and cleft encompassing central zone to disc margin in extrusion(9/12). General irregularity was predominantly grade 3(15/22) and was shown in all except in 2 protrusions. Peripheral width was 0.56 of central radius. Extrusion in herniated disc shows characteristic cleft encompassing central zone to disc margin whereas sequestration or protrusion displays tract extending from peripheral zone to disc margin. Thus, three dimensional surface imaging may aid the diagnosis, follow-up, prediction, and treatment of herniated disc.

  3. Acupuncture and Spontaneous Regression of a Radiculopathic Cervical Herniated Disc

    Directory of Open Access Journals (Sweden)

    Kim Sung-Ha

    2012-06-01

    Full Text Available The spontaneous regression of herniated cervical discs is not a well-established phenomenon. However, we encountered a case of a spontaneous regression of a severe radiculopathic herniated cervical disc that was treated with acupuncture, pharmacopuncture, and herb medicine. The symptoms were improved within 12 months of treatment. Magnetic resonance imaging (MRI conducted at that time revealed marked regression of the herniated disc. This case provides an additional example of spontaneous regression of a herniated cervical disc documented by MRI following non-surgical treatment.

  4. Gene expression profile analysis of human intervertebral disc degeneration

    Directory of Open Access Journals (Sweden)

    Kai Chen

    2013-01-01

    Full Text Available In this study, we used microarray analysis to investigate the biogenesis and progression of intervertebral disc degeneration. The gene expression profiles of 37 disc tissue samples obtained from patients with herniated discs and degenerative disc disease collected by the National Cancer Institute Cooperative Tissue Network were analyzed. Differentially expressed genes between more and less degenerated discs were identified by significant analysis of microarray. A total of 555 genes were significantly overexpressed in more degenerated discs with a false discovery rate of < 3%. Functional annotation showed that these genes were significantly associated with membrane-bound vesicles, calcium ion binding and extracellular matrix. Protein-protein interaction analysis showed that these genes, including previously reported genes such as fibronectin, COL2A1 and f-catenin, may play key roles in disc degeneration. Unsupervised clustering indicated that the widely used morphology-based Thompson grading system was only marginally associated with the molecular classification of intervertebral disc degeneration. These findings indicate that detailed, systematic gene analysis may be a useful way of studying the biology of intervertebral disc degeneration.

  5. Acupuncture and spontaneous regression of a radiculopathic cervical herniated disc.

    Science.gov (United States)

    Kim, Sung-Ha; Park, Man-Young; Lee, Sang-Mi; Jung, Ho-Hyun; Kim, Jae-Kyoun; Lee, Jong-Deok; Kim, Dong-Woung; Yeom, Seung-Ryong; Lim, Jin-Young; Park, Min-Jung; Park, Se-Woon; Kim, Sung-Chul

    2012-06-01

    The spontaneous regression of herniated cervical discs is not a well-established phenomenon. However, we encountered a case of a spontaneous regression of a severe radiculopathic herniated cervical disc that was treated with acupuncture, pharmacopuncture, and herb medicine. The symptoms were improved within 12 months of treatment. Magnetic resonance imaging (MRI) conducted at that time revealed marked regression of the herniated disc. This case provides an additional example of spontaneous regression of a herniated cervical disc documented by MRI following non-surgical treatment.

  6. Spontaneous regression of a lumbar disc herniation: case report

    Directory of Open Access Journals (Sweden)

    Mostarchid Brahim El

    2016-12-01

    Full Text Available Lumbar disc herniation is a common disease that induces back pain and radicular pain. Some cases require conservative treatment or at times relived spontaneously. Spontaneous regression of disc herniation is an atypical clinical presentation, and it has been recognized with the advancement of recent advances in imaging techniques. We present a 35-year-old woman presented a spontaneous regression of a lumbar disc herniation with good outcome after intensive physical therapy program. Spontaneous regression of disc herniation is thought to occur via an inflammatory reaction with molecular mechanisms of phagocytic processes.

  7. Power diagrams and interaction processes for unions of discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisova, Katarina

    We study a flexible class of finite disc process models with interaction between the discs. We let U denote the random set given by the union of discs, and use for the disc process an exponential family density with the canonical sufficient statistic only depending on geometric properties of U......, becomes useful for handling the problem of edge effects when only U is observed within a bounded observation window. The power tessellation and its dual graph become major tools when establishing inclusion-exclusion formulae, formulae for computing geometric characteristics of U, and stability properties...

  8. Power diagrams and interaction processes for unions of discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisova, Katerina

    2008-01-01

     We study a flexible class of finite-disc process models with interaction between the discs. We let U denote the random set given by the union of discs, and use for the disc process an exponential family density with the canonical sufficient statistic depending only on geometric properties of U......, becomes useful for handling the problem of edge effects when only U is observed within a bounded observation window. The power tessellation and its dual graph become major tools when establishing inclusion-exclusion formulae, formulae for computing geometric characteristics of U, and stability properties...

  9. Metallicity gradient of the thick disc progenitor at high redshift

    Science.gov (United States)

    Kawata, Daisuke; Allende Prieto, Carlos; Brook, Chris B.; Casagrande, Luca; Ciucă, Ioana; Gibson, Brad K.; Grand, Robert J. J.; Hayden, Michael R.; Hunt, Jason A. S.

    2018-01-01

    We have developed a novel Markov Chain Monte Carlo chemical 'painting' technique to explore possible radial and vertical metallicity gradients for the thick disc progenitor. In our analysis, we match an N-body simulation to the data from the Apache Point Observatory Galactic Evolution Experiment survey. We assume that the thick disc has a constant scaleheight and has completed its formation at an early epoch, after which time radial mixing of its stars has taken place. Under these assumptions, we find that the initial radial metallicity gradient of the thick disc progenitor should not be negative, but either flat or even positive, to explain the current negative vertical metallicity gradient of the thick disc. Our study suggests that the thick disc was built-up in an inside-out and upside-down fashion, and older, smaller and thicker populations are more metal poor. In this case, star-forming discs at different epochs of the thick disc formation are allowed to have different radial metallicity gradients, including a negative one, which helps to explain a variety of slopes observed in high-redshift disc galaxies. This scenario helps to explain the positive slope of the metallicity-rotation velocity relation observed for the Galactic thick disc. On the other hand, radial mixing flattens the slope of an existing gradient.

  10. Spiral-driven accretion in protoplanetary discs . III. Tridimensional simulations

    Science.gov (United States)

    Hennebelle, Patrick; Lesur, Geoffroy; Fromang, Sébastien

    2017-03-01

    Context. Understanding how accretion proceeds in proto-planetary discs, and more generally, understanding their dynamics, is a crucial questions that needs to be answered to explain the conditions in which planets form. Aims: The role that accretion of gas from the surrounding molecular cloud onto the disc may have on its structure needs to be quantified. Methods: We performed tridimensional simulations using the Cartesian AMR code RAMSES of an accretion disc that is subject to infalling material. Results: For the aspect ratio of H/R ≃ 0.15 and disc mass Md ≃ 10-2M⊙ used in our study, we find that for typical accretion rates of the order of a few 10-7M⊙ yr-1, values of the α parameter as high as a few 10-3 are inferred. The mass that is accreted in the inner part of the disc is typically at least 50% of the total mass that has been accreted onto the disc. Conclusions: Our results suggest that external accretion of gas at moderate values onto circumstellar discs may trigger prominent spiral arms that are reminiscent of recent observations made with various instruments, and may lead to significant transport through the disc. If confirmed from observational studies, such accretion may therefore influence disc evolution.

  11. Notochord Cells in Intervertebral Disc Development and Degeneration

    Directory of Open Access Journals (Sweden)

    Matthew R. McCann

    2016-01-01

    Full Text Available The intervertebral disc is a complex structure responsible for flexibility, multi-axial motion, and load transmission throughout the spine. Importantly, degeneration of the intervertebral disc is thought to be an initiating factor for back pain. Due to a lack of understanding of the pathways that govern disc degeneration, there are currently no disease-modifying treatments to delay or prevent degenerative disc disease. This review presents an overview of our current understanding of the developmental processes that regulate intervertebral disc formation, with particular emphasis on the role of the notochord and notochord-derived cells in disc homeostasis and how their loss can result in degeneration. We then describe the role of small animal models in understanding the development of the disc and their use to interrogate disc degeneration and associated pathologies. Finally, we highlight essential development pathways that are associated with disc degeneration and/or implicated in the reparative response of the tissue that might serve as targets for future therapeutic approaches.

  12. New directions in the treatment of degenerative disc disease

    Directory of Open Access Journals (Sweden)

    Robert Gasik

    2014-11-01

    Full Text Available Degenerative lesions in intervertebral discs rank among the most common causes of spinal pain syndromes. Conservative treatment, pharmacotherapy and rehabilitation focus on the elimination of pain symptoms without addressing the underlying cause of the pain. Surgical techniques applied to date have, in turn, eliminated the cause of the pain while failing to halt the degeneration process affecting the discs. The future of the treatment of degenerative disc lesions lies in methods affecting the nutrition, improving the hydration and stimulating the regeneration of intervertebral discs, as outlined in the present study.

  13. Bovine explant model of degeneration of the intervertebral disc

    Directory of Open Access Journals (Sweden)

    Sivan Sarit

    2008-02-01

    Full Text Available Abstract Background Many new treatments for degeneration of the intervertebral disc are being developed which can be delivered through a needle. These require testing in model systems before being used in human patients. Unfortunately, because of differences in anatomy, there are no ideal animal models of disc degeneration. Bovine explant model systems have many advantages but it is not possible to inject any significant volume into an intact disc. Therefore we have attempted to mimic disc degeneration in an explant bovine model via enzymatic digestion. Methods Bovine coccygeal discs were incubated with different concentrations of the proteolytic enzymes, trypsin and papain, and maintained in culture for up to 3 weeks. A radio-opaque solution was injected to visualise cavities generated. Degenerative features were monitored histologically and biochemically (water and glycosaminoglycan content, via dimethylmethylene blue. Results and Conclusion The central region of both papain and trypsin treated discs was macro- and microscopically fragmented, with severe loss of metachromasia. The integrity of the surrounding tissue was mostly in tact with cells in the outer annulus appearing viable. Biochemical analysis demonstrated greatly reduced glycosaminoglycan content in these compared to untreated discs. We have shown that bovine coccygeal discs, treated with proteolytic enzymes can provide a useful in vitro model system for developing and testing potential new treatments of disc degeneration, such as injectable implants or biological therapies.

  14. Disc electrophoresis and related techniques of polyacrylamide gel electrophoresis

    National Research Council Canada - National Science Library

    Maurer, H. R

    1971-01-01

    ..., enzymes, antingens and radioactively labelled materials, and detailed treatments of micro disc electrophoresis, preparative polyacrylamide gel electrophoresis and many other techniques for special problems...

  15. Determination of the spin diffusion length in germanium by spin optical orientation and electrical spin injection

    Science.gov (United States)

    Rinaldi, C.; Bertoli, S.; Asa, M.; Baldrati, L.; Manzoni, C.; Marangoni, M.; Cerullo, G.; Bianchi, M.; Sordan, R.; Bertacco, R.; Cantoni, M.

    2016-10-01

    The measurement of the spin diffusion length and/or lifetime in semiconductors is a key issue for the realisation of spintronic devices, exploiting the spin degree of freedom of carriers for storing and manipulating information. In this paper, we address such parameters in germanium (0 0 1) at room temperature (RT) by three different measurement methods. Exploiting optical spin orientation in the semiconductor and spin filtering across an insulating MgO barrier, the dependence of the resistivity on the spin of photo-excited carriers in Fe/MgO/Ge spin photodiodes (spin-PDs) was electrically detected. A spin diffusion length of 0.9  ±  0.2 µm was obtained by fitting the photon energy dependence of the spin signal by a mathematical model. Electrical techniques, comprising non-local four-terminal and Hanle measurements performed on CoFeB/MgO/Ge lateral devices, led to spin diffusion lengths of 1.3  ±  0.2 µm and 1.3  ±  0.08 µm, respectively. Despite minor differences due to experimental details, the order of magnitude of the spin diffusion length is the same for the three techniques. Although standard electrical methods are the most employed in semiconductor spintronics for spin diffusion length measurements, here we demonstrate optical spin orientation as a viable alternative for the determination of the spin diffusion length in semiconductors allowing for optical spin orientation.

  16. Percutaneous thoracic intervertebral disc nucleoplasty: technical notes from 3 patients with painful thoracic disc herniations

    NARCIS (Netherlands)

    Chua Hai Liang, N.; Gultuna, I.; Riezebos, P.; Beems, T.; Vissers, K.C.P.

    2011-01-01

    Symptomatic thoracic disc herniation is an uncommon condition and early surgical approaches were associated with significant morbidity and even mortality. We are the first to describe the technique of percutaneous thoracic nucleoplasty in three patients with severe radicular pain due to thoracic

  17. Analysis of crucial molecules involved in herniated discs and degenerative disc disease

    Directory of Open Access Journals (Sweden)

    Zhigang Qu

    2013-01-01

    Full Text Available OBJECTIVES: Herniated discs and degenerative disc disease are major health problems worldwide. However, their pathogenesis remains obscure. This study aimed to explore the molecular mechanisms of these ailments and to identify underlying therapeutic targets. MATERIAL AND METHODS: Using the GSE23130 microarray datasets downloaded from the Gene Expression Omnibus database, differentially co-expressed genes and links were identified using the differentially co-expressed gene and link method with a false discovery rate ,0.25 as a significant threshold. Subsequently, the underlying molecular mechanisms of the differential co-expression of these genes were investigated using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. In addition, the transcriptional regulatory relationship was also investigated. RESULTS: Through the analysis of the gene expression profiles of different specimens from patients with these diseases, 539 differentially co-expressed genes were identified for these ailments. The ten most significant signaling pathways involving the differentially co-expressed genes were identified by enrichment analysis. Among these pathways, apoptosis and extracellular matrix-receptor interaction pathways have been reported to be related to these diseases. A total of 62 pairs of regulatory relationships between transcription factors and their target genes were identified as critical for the pathogenesis of these diseases. CONCLUSION: The results of our study will help to identify the mechanisms responsible for herniated discs and degenerative disc disease and provides a theoretical basis for further therapeutic study.

  18. Analysis of crucial molecules involved in herniated discs and degenerative disc disease.

    Science.gov (United States)

    Qu, Zhigang; Miao, Weiwei; Zhang, Qi; Wang, Zhenyu; Fu, Changfeng; Han, Jinhua; Liu, Yi

    2013-01-01

    Herniated discs and degenerative disc disease are major health problems worldwide. However, their pathogenesis remains obscure. This study aimed to explore the molecular mechanisms of these ailments and to identify underlying therapeutic targets. Using the GSE23130 microarray datasets downloaded from the Gene Expression Omnibus database, differentially co-expressed genes and links were identified using the differentially co-expressed gene and link method with a false discovery rate ,0.25 as a significant threshold. Subsequently, the underlying molecular mechanisms of the differential co-expression of these genes were investigated using Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis. In addition, the transcriptional regulatory relationship was also investigated. Through the analysis of the gene expression profiles of different specimens from patients with these diseases, 539 differentially co-expressed genes were identified for these ailments. The ten most significant signaling pathways involving the differentially co-expressed genes were identified by enrichment analysis. Among these pathways, apoptosis and extracellular matrix-receptor interaction pathways have been reported to be related to these diseases. A total of 62 pairs of regulatory relationships between transcription factors and their target genes were identified as critical for the pathogenesis of these diseases. The results of our study will help to identify the mechanisms responsible for herniated discs and degenerative disc disease and provides a theoretical basis for further therapeutic study.

  19. Beyond the standard model of the disc-line spectral profiles from black hole accretion discs

    Czech Academy of Sciences Publication Activity Database

    Sochora, Vjačeslav; Karas, Vladimír; Svoboda, Jiří; Dovčiak, Michal

    2014-01-01

    Roč. 54, č. 4 (2014), s. 301-304 ISSN 1210-2709 R&D Projects: GA ČR(CZ) GC13-00070J Institutional support: RVO:67985815 Keywords : accretion discs * black hole physics * galactic nuclei Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  20. Inner disc obscuration in GRS 1915+105 based on relativistic slim disc model

    Czech Academy of Sciences Publication Activity Database

    Vierdayanti, K.; Sądowski, A.; Mineshige, L.S.; Bursa, Michal

    2013-01-01

    Roč. 436, č. 1 (2013), s. 71-81 ISSN 0035-8711 Institutional support: RVO:67985815 Keywords : accretion discs * black hole physics * GRS 1915+105 Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 5.226, year: 2013

  1. Confirming chemical clocks: asteroseismic age dissection of the Milky Way disc(s)

    DEFF Research Database (Denmark)

    Silva Aguirre, V.; Bojsen-Hansen, M.; Slumstrup, D.

    2018-01-01

    Investigations of the origin and evolution of the Milky Way disc have long relied on chemical and kinematic identifications of its components to reconstruct our Galactic past. Difficulties in determining precise stellar ages have restricted most studies to small samples, normally confined...

  2. Spin diffusion length of Permalloy using spin absorption in lateral spin valves

    Science.gov (United States)

    Sagasta, Edurne; Omori, Yasutomo; Isasa, Miren; Otani, YoshiChika; Hueso, Luis E.; Casanova, Fèlix

    2017-08-01

    We employ the spin absorption technique in lateral spin valves to extract the spin diffusion length of Permalloy (Py) as a function of temperature and resistivity. A linear dependence of the spin diffusion length with the conductivity of Py is observed, evidencing that the Elliott-Yafet mechanism is the dominant spin relaxation mechanism in Permalloy. Completing the dataset with additional data found in the literature, we obtain λPy = (0.91 ± 0.04) (fΩm2)/ρPy.

  3. Muon spin rotation studies

    Science.gov (United States)

    1984-01-01

    The bulk of the muon spin rotation research work centered around the development of the muon spin rotation facility at the Alternating Gradient Synchrotron (AGS) of Brookhaven National Laboratory (BNL). The collimation system was both designed and fabricated at Virginia State University. This improved collimation system, plus improvements in detectors and electronics enabled the acquisition of spectra free of background out to 15 microseconds. There were two runs at Brookhaven in 1984, one run was devoted primarily to beam development and the other run allowed several successful experiments to be performed. The effect of uniaxial strain on an Fe(Si) crystal at elevated temperature (360K) was measured and the results are incorporated herein. A complete analysis of Fe pulling data taken earlier is included.

  4. Spin and Madelung fluid

    International Nuclear Information System (INIS)

    Salesi, G.

    1995-07-01

    Starting from the Pauli current the decomposition of the non-relativistic local velocity has been obtained in two parts (in the ordinary tensorial language): one parallel and the other orthogonal to the impulse. The former is recognized to be the classical part, that is, the center-of-mass (CM) velocity, and the latter the quantum one, that is, the velocity of the motion in the CM frame (namely, the internal spin motion or Zitterbewegung). Inserting this complete, composite expression of the velocity into the kinetic energy term of the classical non-relativistic (i.e. Newtonian) Lagrangian, the author straightforwardly get the appearance of the so called quantum potential associates as it is known, to the Madelung fluid. In such a way, the quantum mechanical behaviour of particles appears to be strictly correlated to the existence of spin and Zitterbewegung

  5. Percutaneous treatment of lumbar disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Leonardi, M.; Resta, F.; Bettinelli, A. [Ospedale Maggiore di Milano (Italy); Lavaroni, A.; Fabris, G. [Ospedale Civile di Udine (Italy); Abelli, F. [Fondazione Clinica del Lavorno, Pavia (Italy)

    1994-12-31

    918 patients were subjected to percutaneous treatment of lumbar herniated disc. 733 of these were treated through enzymatic nucleolysis with chymopapain, for a total 883 levels. Chemonucleolysis was carried out on 733 patients (79.8%). Automated discectomy has been carried out in 185 cases (20.1%). Chemonucleolysis has led to the resolution of the symptoms in a high percentage of cases (82.2%). Nucleotomy has proved to be an effective method in 74.6% of cases. (author). 7 refs, 6 figs, 1 tab.

  6. Likelihood inference for unions of interacting discs

    DEFF Research Database (Denmark)

    Møller, Jesper; Helisova, K.

    2010-01-01

    This is probably the first paper which discusses likelihood inference for a random set using a germ-grain model, where the individual grains are unobservable, edge effects occur and other complications appear. We consider the case where the grains form a disc process modelled by a marked point...... with respect to a given marked Poisson model (i.e. a Boolean model). We show how edge effects and other complications can be handled by considering a certain conditional likelihood. Our methodology is illustrated by analysing Peter Diggle's heather data set, where we discuss the results of simulation......-based maximum likelihood inference and the effect of specifying different reference Poisson models....

  7. Pangaea, She No Spin

    Science.gov (United States)

    McDowell, M.

    2002-12-01

    Looking at lopsided Pangaea, shown imaginatively on many illustrated proposals, I wondered what would happen if the configuration were put in high relief on a globe and spun on axis. Then I wondered if the present configuration of land masses would itself balance as a spinning top. So I got two Replogle globes, two boxes of colored modeling clay sticks, and two fat knitting needles, to fit through the capped holes at the poles of the globes. The clay sticks I cut up into 3 mm. (1/8") slices, using a different color for each continent, and applied to the first globe, assuming the extreme exaggeration above the geoid, no matter how crude, would tell the story. Inserting one needle through the globe and securing it, I balanced the globe on the point of the needle and twirled it like a top. Result: Wobbly! Top end of needle gyrated unevenly, and here it was supposed to make a smooth precessional cone. Oh boy. For the second globe, I used a Scotese "free stuff" interpretation of Pangaea, which I had to augment considerably using USGS, DuToit, Irving and other references, fitting it on the globe and applying identical clay color slices to what I judged generally accepted land surfaces. Result: the thing would hardly stand up, let alone spin. Conclusion: Although a refinement of application on the "today" globe might eliminate nutation, creating a smoother spin, there is no way any refinement of Pangaea on the same size globe can come close. While the concept of a supercontinent may be viable, I theorize that it had to have evolved on a far smaller globe, where land mass could balance, and the "breakup" would not have caused us to wildly gyrate on our axis. Because Pangaea, she no spin.

  8. Spin Hall effect

    Czech Academy of Sciences Publication Activity Database

    Sinova, Jairo; Valenzuela, O.V.; Wunderlich, Joerg; Back, C.H.; Jungwirth, Tomáš

    2015-01-01

    Roč. 87, č. 4 (2015), s. 1213-1259 ISSN 0034-6861 R&D Projects: GA MŠk(CZ) LM2011026; GA ČR GB14-37427G EU Projects: European Commission(XE) 268066 - 0MSPIN Institutional support: RVO:68378271 Keywords : spin Hall effect * spintronics Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 33.177, year: 2015

  9. Spin and gravitation

    Science.gov (United States)

    Ray, J. R.

    1982-01-01

    The fundamental variational principle for a perfect fluid in general relativity is extended so that it applies to the metric-torsion Einstein-Cartan theory. Field equations for a perfect fluid in the Einstein-Cartan theory are deduced. In addition, the equations of motion for a fluid with intrinsic spin in general relativity are deduced from a special relativistic variational principle. The theory is a direct extension of the theory of nonspinning fluids in special relativity.

  10. Spinning Disk Confocal System

    Science.gov (United States)

    2006-06-01

    high temporal resolution. An instrument has been developed for exactly this type of live-cell imaging. This new instrument scans 1000 microbeams across...Imaging System. Instead of scanning a single laser beam across the cell, this new instrument scans 1000 microbeams simultaneously using a spinning...multipoint-excitation, multipoint- emission characteristics of UltraView RS, which confers three main advantages over traditional beam scanning LSCMs for

  11. Spinning out a star.

    Science.gov (United States)

    Lord, Michael D; Mandel, Stanley W; Wager, Jeffrey D

    2002-06-01

    Spinouts rarely take off; most, in fact, fall into one or more of four traps that doom them from the start. Some companies spin out ventures that are too close to the core of their businesses, in effect selling off their crown jewels. Sometimes, a parent company uses the spinout primarily to pawn off debt or expenses or to quickly raise external capital for itself. Other times, a company may try to spin out an area of its business that lacks one or more of the critical legs of a successful company--a coherent business model, say, or a solid financial base. And in many cases, parent companies can't bring themselves to sever their ownership ties and give up control of their spinouts. R.J. Reynolds, the tobacco giant, managed to avoid these traps when it successfully spun out a most unlikely venture, the pharmaceutical company Targacept. As the story illustrates, the problem with spinouts is similar to the problem of rich children. Their parents have the wherewithal to spoil them or shelter them or cling to them, but what they need is tough love and discipline--much the same discipline that characterizes successful start-ups. R.J. Reynolds recognized that it didn't know that much about the pharmaceutical business and couldn't merely try to spin out a small clone of itself. It had to treat the venture as if it were essentially starting from scratch, with a passionate entrepreneurial leader, a solid business plan, help from outside partners in the industry, and ultimately substantial venture backing. That these lessons are less obvious to executives contemplating spinning out ventures closer to their core businesses may be why so many spinouts fail.

  12. Spinning geometry = Twisted geometry

    International Nuclear Information System (INIS)

    Freidel, Laurent; Ziprick, Jonathan

    2014-01-01

    It is well known that the SU(2)-gauge invariant phase space of loop gravity can be represented in terms of twisted geometries. These are piecewise-linear-flat geometries obtained by gluing together polyhedra, but the resulting geometries are not continuous across the faces. Here we show that this phase space can also be represented by continuous, piecewise-flat three-geometries called spinning geometries. These are composed of metric-flat three-cells glued together consistently. The geometry of each cell and the manner in which they are glued is compatible with the choice of fluxes and holonomies. We first remark that the fluxes provide each edge with an angular momentum. By studying the piecewise-flat geometries which minimize edge lengths, we show that these angular momenta can be literally interpreted as the spin of the edges: the geometries of all edges are necessarily helices. We also show that the compatibility of the gluing maps with the holonomy data results in the same conclusion. This shows that a spinning geometry represents a way to glue together the three-cells of a twisted geometry to form a continuous geometry which represents a point in the loop gravity phase space. (paper)

  13. Spin Foam Models

    CERN Document Server

    Krasnov, K V

    1999-01-01

    The term ‘spin foam models’ was invented only a couple years ago by Baez to refer to a new approach to quantization of general relativity that appeared as an offsping of loop quantum gravity. Although this new approach was motivated, both logically and historically, by loop quantum gravity, it became clear by now that the two approaches are rather independent. While loop quantum gravity attempts to give a canonical quantization of general relativity, spin foam model approach is set to make sense of the path integral for gravity. Eventually, the two approaches will probably be shown to be equivalent, but no rigorous result to this effect exists as for now. In this thesis I develop the spin foam quantization of gravity from scratch, referring to results from loop quantum gravity only for comparison. I start from a review of 2 + 1 gravity and discuss different roots to quantize it. While some of them, as, for example, using Chern-Simons theory, only exist in 2 + 1, others can be generalized t...

  14. Supersonic turbulence, filamentary accretion and the rapid assembly of massive stars and discs

    Science.gov (United States)

    Banerjee, Robi; Pudritz, Ralph E.; Anderson, Dave W.

    2006-12-01

    We present a detailed computational study of the assembly of protostellar discs and massive stars in molecular clouds with supersonic turbulence. We follow the evolution of large-scale filamentary structures in a cluster-forming clump down to protostellar length-scales by means of very highly resolved, 3D adaptive mesh refined (AMR) simulations, and show how accretion discs and massive stars form in such environments. We find that an initially elongated cloud core which has a slight spin from oblique shocks collapses first to a filament and later develops a turbulent disc close to the centre of the filament. The continued large-scale flow that shocks with the filament maintains the high density and pressure within it. Material within the cooling filament undergoes gravitational collapse and an outside-in assembly of a massive protostar. Our simulations show that very high mass accretion rates of up to 10-2Msolaryr-1 and high, supersonic, infall velocities result from such filamentary accretion. Accretion at these rates is higher by an order of magnitude than those found in semi-analytic studies, and can quench the radiation field of a growing massive young star. Our simulations include a comprehensive set of the important chemical and radiative processes such as cooling by molecular line emission, gas-dust interaction and radiative diffusion in the optically thick regime, as well as H2 formation and dissociation. Therefore, we are able to probe, for the first time, the relevant physical phenomena on all scales from those characterizing the clump down to protostellar core.

  15. Genome-Wide Association Study in Dachshund: Identification of a Major Locus Affecting Intervertebral Disc Calcification

    DEFF Research Database (Denmark)

    Mogensen, Mette Sloth; Karlskov-Mortensen, Peter; Proschowsky, Helle Friis

    2011-01-01

    Intervertebral disc calcification and herniation commonly affects Dachshund where the predisposition is caused by an early onset degenerative process resulting in disc calcification. A continuous spectrum of disc degeneration is seen within and among clog breeds, suggesting a multifactorial etiol...

  16. Biomechanical and biochemical outcomes of porcine temporomandibular joint disc deformation.

    Science.gov (United States)

    Matuska, Andrea M; Muller, Stephen; Dolwick, M Franklin; McFetridge, Peter S

    2016-04-01

    The structure-function relationship in the healthy temporomandibular joint (TMJ) disc has been well established, however the changes in dysfunctional joints has yet to be systematically evaluated. Due to the poor understanding of the etiology of temporomandibular disorders (TMDs) this study evaluated naturally occurring degenerative remodeling in aged female porcine temporomandibular joint (TMJ) discs in order to gain insight into the progression and effects on possible treatment strategies of TMDs. Surface and regional biomechanical and biochemical properties of discal tissues were determined in grossly deformed (≥Wilkes Stage 3) and morphologically normal (≤Wilkes Stage 2) TMJ discs. Compared to normal disc structure the deformed discs lacked a smooth biconcave shape and characteristic ECM organization. Reduction in tensile biomechanical integrity and increased compressive stiffness and cellularity was found in deformed discs. Regionally, the posterior and intermediate zones of the disc were most frequently affected along with the inferior surface. The frequency of degeneration observed on the inferior surface of the disc (predominantly posterior), suggests that a disruption in the disc-condyle relationship likely contributes to the progression of joint dysfunction more than the temporodiscal relationship. As such, the inferior joint space may be an important consideration in early clinical diagnosis and treatment of TMDs, as it is overlooked in techniques performed in the upper joint space, including arthroscopy and arthrocentesis. Furthermore, permanent damage to the disc mechanical properties would limit the ability to successfully reposition deformed discs, highlighting the importance of emerging therapies such as tissue engineering. Copyright © 2016 Elsevier Ltd. All rights reserved.

  17. Retinal Nerve Fiber Layer Protrusion Associated with Tilted Optic Discs.

    Science.gov (United States)

    Chiang, Jaclyn; Yapp, Michael; Ly, Angelica; Hennessy, Michael P; Kalloniatis, Michael; Zangerl, Barbara

    2018-03-01

    This study resulted in the identification of an optic nerve head (ONH) feature associated with tilted optic discs, which might potentially contribute to ONH pathologies. Knowledge of such findings will enhance clinical insights and drive future opportunities to understand disease processes related to tilted optic discs. The aim of this study was to identify novel retinal nerve fiber layer (RNFL) anomalies by evaluating tilted optic discs using optical coherence tomography. An observed retinal nerve fiber protrusion was further investigated for association with other morphological or functional parameters. A retrospective review of 400 randomly selected adult patients with ONH examinations was conducted in a referral-only, diagnostic imaging center. After excluding other ONH pathologies, 215 patients were enrolled and evaluated for optic disc tilt and/or torsion. Gross anatomical ONH features, including size and rim or parapapillary region elevation, were assessed with stereoscopic fundus photography. Optical coherence tomography provided detailed morphological information of individual retinal layers. Statistical analysis was applied to identify significant changes between individual patient cohorts. A dome-shaped hyperreflective RNFL bulge, protruding into the neurosensory retina at the optic disc margins, was identified in 17 eyes with tilted optic discs. Available follow-up data were inconclusive regarding natural changes with this ONH feature. This RNFL herniation was significantly correlated with smaller than average optic disc size (P = .005), congenital disc tilt (P optic discs, which has not previously been assessed as an independent ONH structure. The feature is predominantly related to congenital crowded, small optic discs and variable between patients. This study is an important first step to elucidate diagnostic capabilities of tilted disc morphological changes and understanding associated functional deficits.

  18. Spinning particle approach to higher spin field theory

    International Nuclear Information System (INIS)

    Corradini, Olindo

    2011-01-01

    We shortly review on the connection between higher-spin gauge field theories and supersymmetric spinning particle models. In such approach the higher spin equations of motion are linked to the first-class constraint algebra associated with the quantization of particle models. Here we consider a class of spinning particle models characterized by local O(N)-extended supersymmetry since these models are known to provide an alternative approach to the geometric formulation of higher spin field theory. We describe the canonical quantization of the models in curved target space and discuss the obstructions that appear in presence of an arbitrarily curved background. We then point out the special role that conformally flat spaces appear to have in such models and present a derivation of the higher-spin curvatures for maximally symmetric spaces.

  19. Entanglement entropy in random quantum spin-S chains

    International Nuclear Information System (INIS)

    Saguia, A.; Boechat, B.; Continentino, M. A.; Sarandy, M. S.

    2007-01-01

    We discuss the scaling of entanglement entropy in the random singlet phase (RSP) of disordered quantum magnetic chains of general spin S. Through an analysis of the general structure of the RSP, we show that the entanglement entropy scales logarithmically with the size of a block, and we provide a closed expression for this scaling. This result is applicable for arbitrary quantum spin chains in the RSP, being dependent only on the magnitude S of the spin. Remarkably, the logarithmic scaling holds for the disordered chain even if the pure chain with no disorder does not exhibit conformal invariance, as is the case for Heisenberg integer-spin chains. Our conclusions are supported by explicit evaluations of the entanglement entropy for random spin-1 and spin-3/2 chains using an asymptotically exact real-space renormalization group approach

  20. Spin current through quantum-dot spin valves

    International Nuclear Information System (INIS)

    Wang, J; Xing, D Y

    2006-01-01

    We report a theoretical study of the influence of the Coulomb interaction on the equilibrium spin current in a quantum-dot spin valve, in which the quantum dot described by the Anderson impurity model is coupled to two ferromagnetic leads with noncollinear magnetizations. In the Kondo regime, electrons transmit through the quantum dot via higher-order virtual processes, in which the spin of either lead electrons or a localized electron on the quantum dot may reverse. It is found that the magnitude of the spin current decreases with increasing Coulomb interactions due to spin flip effects on the dot. However, the spatial direction of the spin current remains unchanged; it is determined only by the exchange coupling between two noncollinear magnetizations

  1. Development of a whole disc organ culture system to study human intervertebral disc

    Science.gov (United States)

    Parolin, M.; Gawri, R.; Mwale, F.; Steffen, T.; Roughley, P.; Antoniou, J.; Jarzem, P.; Haglund, L.; Ouellet, J.

    2010-01-01

    Study type: Basic science Objective: Low back pain is one of the most common health problems1 and is strongly associated with intervertebral disc degeneration, (IVD). Current treatments remove the symptoms without reversing or even retarding the underlying problem. Development of new therapy for the regeneration of the degenerative IVD is complicated by the lack of a validated long-term organ culture model in which therapeutic candidates can be studied. The object of this study was to develop, optimize, and validate an organ culture model for human IVD, allowing for the study of degeneration and the potential for regeneration of the human IVD. Methods: From eleven donors, an average of 5–6 IVDs were obtained. Inclusion criteria were; age between 50 and 70 years old, no history of cancer, chemotherapy, diabetes, or liver cirrhosis. An x-ray of the harvested spine was done to assess the grade of degeneration. Three different methods for isolating the discs were studied: with bony endplate (BEP), without endplate (NEP), and with cartilage endplate (CEP). Discs were cultured for 4 weeks without external load, in Dulbecco's modified eagle media with glucose and fetal bovine serum (FBS). Four different combinations of concentrations of glucose and FBS were compared: low glucose-low FBS, low glucose-high FBS, high glucose-low FBS, and high glucose-high FBS.2 Short-term cultures (1 week) were performed to compare the cell viability of the three methods of isolating the discs. Swelling potential on NEP and CEP discs from the same donor were evaluated. After four weeks of culture, a 4 mm punch was taken from CEP discs and cell viability was evaluated using a live/dead assay with confocal microscopy. Results: Analyzing the potential of swelling in CEP discs, there was an increase in volume to a maximum of 25% and retention of shape and morphology. Whereas in NEP discs, there was an excessive deformation and a two-fold time increase in volume than CEP discs. The cell

  2. Spin Transfer Torque in Graphene

    Science.gov (United States)

    Lin, Chia-Ching; Chen, Zhihong

    2014-03-01

    Graphene is an idea channel material for spin transport due to its long spin diffusion length. To develop graphene based spin logic, it is important to demonstrate spin transfer torque in graphene. Here, we report the experimental measurement of spin transfer torque in graphene nonlocal spin valve devices. Assisted by a small external in-plane magnetic field, the magnetization reversal of the receiving magnet is induced by pure spin diffusion currents from the injector magnet. The magnetization switching is reversible between parallel and antiparallel configurations by controlling the polarity of the applied charged currents. Current induced heating and Oersted field from the nonlocal charge flow have also been excluded in this study. Next, we further enhance the spin angular momentum absorption at the interface of the receiving magnet and graphene channel by removing the tunneling barrier in the receiving magnet. The device with a tunneling barrier only at the injector magnet shows a comparable nonlocal spin valve signal but lower electrical noise. Moreover, in the same preset condition, the critical charge current density for spin torque in the single tunneling barrier device shows a substantial reduction if compared to the double tunneling barrier device.

  3. Spin waves and spin instabilities in quantum plasmas

    OpenAIRE

    Andreev, P. A.; Kuz'menkov, L. S.

    2014-01-01

    We describe main ideas of method of many-particle quantum hydrodynamics allows to derive equations for description of quantum plasma evolution. We also present definitions of collective quantum variables suitable for quantum plasmas. We show that evolution of magnetic moments (spins) in quantum plasmas leads to several new branches of wave dispersion: spin-electromagnetic plasma waves and self-consistent spin waves. Propagation of neutron beams through quantum plasmas is also considered. Inst...

  4. Hardy's argument and successive spin-s measurements

    International Nuclear Information System (INIS)

    Ahanj, Ali

    2010-01-01

    We consider a hidden-variable theoretic description of successive measurements of noncommuting spin observables on an input spin-s state. In this scenario, the hidden-variable theory leads to a Hardy-type argument that quantum predictions violate it. We show that the maximum probability of success of Hardy's argument in quantum theory is ((1/2)) 4s , which is more than in the spatial case.

  5. The cellular memory disc of reprogrammed cells.

    Science.gov (United States)

    Anjamrooz, Seyed Hadi

    2013-04-01

    The crucial facts underlying the low efficiency of cellular reprogramming are poorly understood. Cellular reprogramming occurs in nuclear transfer, induced pluripotent stem cell (iPSC) formation, cell fusion, and lineage-switching experiments. Despite these advances, there are three fundamental problems to be addressed: (1) the majority of cells cannot be reprogrammed, (2) the efficiency of reprogramming cells is usually low, and (3) the reprogrammed cells developed from a patient's own cells activate immune responses. These shortcomings present major obstacles for using reprogramming approaches in customised cell therapy. In this Perspective, the author synthesises past and present observations in the field of cellular reprogramming to propose a theoretical picture of the cellular memory disc. The current hypothesis is that all cells undergo an endogenous and exogenous holographic memorisation such that parts of the cellular memory dramatically decrease the efficiency of reprogramming cells, act like a barrier against reprogramming in the majority of cells, and activate immune responses. Accordingly, the focus of this review is mainly to describe the cellular memory disc (CMD). Based on the present theory, cellular memory includes three parts: a reprogramming-resistance memory (RRM), a switch-promoting memory (SPM) and a culture-induced memory (CIM). The cellular memory arises genetically, epigenetically and non-genetically and affects cellular behaviours. [corrected].

  6. Elasticplastic discs under plane stress conditions

    CERN Document Server

    Alexandrov, Sergey

    2015-01-01

    This Volume presents a unified approach to calculate the plane stress distribution of stress and strain in thin elastic/plastic discs subject to various loading conditions. There is a vast amount of literature on analytical and semi-analytical solutions for such discs obeying Tresca’s yield criterion and its associated flow rule. On the other hand, most of analytical and semi-analytical solutions for Mises yield criterion are based on the deformation theory of plasticity. A distinguished feature of the solutions given in the present volume is that the flow theory of plasticity and Mises yield criterion are adopted. The solutions are semi-analytical in the sense that numerical methods are only necessary to evaluate ordinary integrals and solve transcendental equations. The book shows that under certain conditions solutions based on the deformation and flow theories of plasticity coincide. All the solutions are illustrated with numerical examples. The goal of the book is to provide the reader with a vision an...

  7. Secular Instabilities of Keplerian Stellar Discs

    Science.gov (United States)

    Kaur, Karamveer; Kazandjian, Mher; Sridhar, S.; Touma, Jihad

    2018-02-01

    We present idealized models of a razor-thin, axisymmetric, Keplerian stellar disc around a massive black hole, and study non-axisymmetric secular instabilities in the absence of either counter-rotation or loss cones. These discs are prograde mono-energetic waterbags, whose phase space distribution functions are constant for orbits within a range of eccentricities (e) and zero outside this range. The linear normal modes of waterbags are composed of sinusoidal disturbances of the edges of distribution function in phase space. Waterbags which include circular orbits (polarcaps) have one stable linear normal mode for each azimuthal wavenumber m. The m = 1 mode always has positive pattern speed and, for polarcaps consisting of orbits with e normal modes for each m, which can be stable or unstable. We derive analytical expressions for the instability condition, pattern speeds, growth rates and normal mode structure. Narrow bands are unstable to modes with a wide range in m. Numerical simulations confirm linear theory and follow the non-linear evolution of instabilities. Long-time integration suggests that instabilities of different m grow, interact non-linearly and relax collisionlessly to a coarse-grained equilibrium with a wide range of eccentricities.

  8. The reports of thick discs' deaths are greatly exaggerated. Thick discs are NOT artefacts caused by diffuse scattered light

    Science.gov (United States)

    Comerón, S.; Salo, H.; Knapen, J. H.

    2018-02-01

    Recent studies have made the community aware of the importance of accounting for scattered light when examining low-surface-brightness galaxy features such as thick discs. In our past studies of the thick discs of edge-on galaxies in the Spitzer Survey of Stellar Structure in Galaxies - the S4G - we modelled the point spread function as a Gaussian. In this paper we re-examine our results using a revised point spread function model that accounts for extended wings out to more than 2\\farcm5. We study the 3.6 μm images of 141 edge-on galaxies from the S4G and its early-type galaxy extension. Thus, we more than double the samples examined in our past studies. We decompose the surface-brightness profiles of the galaxies perpendicular to their mid-planes assuming that discs are made of two stellar discs in hydrostatic equilibrium. We decompose the axial surface-brightness profiles of galaxies to model the central mass concentration - described by a Sérsic function - and the disc - described by a broken exponential disc seen edge-on. Our improved treatment fully confirms the ubiquitous occurrence of thick discs. The main difference between our current fits and those presented in our previous papers is that now the scattered light from the thin disc dominates the surface brightness at levels below μ 26 mag arcsec-2. We stress that those extended thin disc tails are not physical, but pure scattered light. This change, however, does not drastically affect any of our previously presented results: 1) Thick discs are nearly ubiquitous. They are not an artefact caused by scattered light as has been suggested elsewhere. 2) Thick discs have masses comparable to those of thin discs in low-mass galaxies - with circular velocities vc< 120 km s-1 - whereas they are typically less massive than the thin discs in high-mass galaxies. 3) Thick discs and central mass concentrations seem to have formed at the same epoch from a common material reservoir. 4) Approximately 50% of the up

  9. Spin transport in spin filtering magnetic tunneling junctions.

    Science.gov (United States)

    Li, Yun; Lee, Eok Kyun

    2007-11-01

    Taking into account spin-orbit coupling and s-d interaction, we investigate spin transport properties of the magnetic tunneling junctions with spin filtering barrier using Landauer-Büttiker formalism implemented with the recursive algorithm to calculate the real-space Green function. We predict completely different bias dependence of negative tunnel magnetoresistance (TMR) between the systems composed of nonmagnetic electrode (NM)/ferromagnetic barrier (FB)/ferromagnet (FM) and NM/FB/FM/NM spin filtering tunnel junctions (SFTJs). Analyses of the results provide us possible ways of designing the systems which modulate the TMR in the negative magnetoresistance regime.

  10. Spin-orbit mediated control of spin qubits

    DEFF Research Database (Denmark)

    Flindt, Christian; Sørensen, A.S; Flensberg, Karsten

    2006-01-01

    We propose to use the spin-orbit interaction as a means to control electron spins in quantum dots, enabling both single-qubit and two-qubit operations. Very fast single-qubit operations may be achieved by temporarily displacing the electrons. For two-qubit operations the coupling mechanism is based...... on a combination of the spin-orbit coupling and the mutual long-ranged Coulomb interaction. Compared to existing schemes using the exchange coupling, the spin-orbit induced coupling is less sensitive to random electrical fluctuations in the electrodes defining the quantum dots....

  11. High-field spin dynamics of antiferromagnetic quantum spin chains

    DEFF Research Database (Denmark)

    Enderle, M.; Regnault, L.P.; Broholm, C.

    2000-01-01

    present recent work on the high-field spin dynamics of the S = I antiferromagnetic Heisenberg chains NENP (Haldane ground state) and CsNiCl3 (quasi-1D HAF close to the quantum critical point), the uniform S = 1/2 chain CTS, and the spin-Peierls system CuGeO3. (C) 2000 Elsevier Science B,V. All rights......The characteristic internal order of macroscopic quantum ground states in one-dimensional spin systems is usually not directly accessible, but reflected in the spin dynamics and the field dependence of the magnetic excitations. In high magnetic fields quantum phase transitions are expected. We...

  12. Visualizing spin states using the spin coherent state representation

    Science.gov (United States)

    Lee Loh, Yen; Kim, Monica

    2015-01-01

    Orbital angular momentum eigenfunctions are readily understood in terms of spherical harmonics. However, the quantum mechanical phenomenon of spin is often said to be mysterious and hard to visualize, with no classical analog. Many textbooks give a heuristic and somewhat unsatisfying picture of a precessing spin vector. Here, we show that the spin-coherent-state representation is a striking, elegant, and mathematically meaningful tool for visualizing spin states. We also demonstrate that cartographic projections such as the Hammer projection are useful for visualizing functions defined on spherical surfaces.

  13. Spin Currents and Spin Orbit Torques in Ferromagnets and Antiferromagnets

    Science.gov (United States)

    Hung, Yu-Ming

    This thesis focuses on the interactions of spin currents and materials with magnetic order, e.g., ferromagnetic and antiferromagnetic thin films. The spin current is generated in two ways. First by spin-polarized conduction-electrons associated with the spin Hall effect in heavy metals (HMs) and, second, by exciting spin-waves in ferrimagnetic insulators using a microwave frequency magnetic field. A conduction-electron spin current can be generated by spin-orbit coupling in a heavy non-magnetic metal and transfer its spin angular momentum to a ferromagnet, providing a means of reversing the magnetization of perpendicularly magnetized ultrathin films with currents that flow in the plane of the layers. The torques on the magnetization are known as spin-orbit torques (SOT). In the first part of my thesis project I investigated and contrasted the quasistatic (slowly swept current) and pulsed current-induced switching characteristics of micrometer scale Hall crosses consisting of very thin (thesis project studies and considers applications of SOT-driven domain wall (DW) motion in a perpendicularly magnetized ultrathin ferromagnet sandwiched between a heavy metal and an oxide. My experiment results demonstrate that the DW motion can be explained by a combination of the spin Hall effect, which generates a SOT, and Dzyaloshinskii-Moriya interaction, which stabilizes chiral Neel-type DW. Based on SOT-driven DW motion and magnetic coupling between electrically isolated ferromagnetic elements, I proposed a new type of spin logic devices. I then demonstrate the device operation by using micromagnetic modeling which involves studying the magnetic coupling induced by fringe fields from chiral DWs in perpendicularly magnetized nanowires. The last part of my thesis project reports spin transport and spin-Hall magnetoresistance (SMR) in yttrium iron garnet Y3Fe5O 12 (YIG)/NiO/Pt trilayers with varied NiO thickness. To characterize the spin transport through NiO we excite

  14. QED approach to the nuclear spin-spin coupling tensor

    International Nuclear Information System (INIS)

    Romero, Rodolfo H.; Aucar, Gustavo A.

    2002-01-01

    A quantum electrodynamical approach for the calculation of the nuclear spin-spin coupling tensor of nuclear-magnetic-resonance spectroscopy is given. Quantization of radiation fields within the molecule is considered and expressions for the magnetic field in the neighborhood of a nucleus are calculated. Using a generalization of time-dependent response theory, an effective spin-spin interaction is obtained from the coupling of nuclear magnetic moments to a virtual quantized magnetic field. The energy-dependent operators obtained reduce to usual classical-field expressions at suitable limits

  15. The truncation of stellar discs : The magnetic hypothesis

    NARCIS (Netherlands)

    Battaner, E; Florido, E; Jimenez-Vicente, J

    We propose a hypothesis of the truncation of stellar discs based on the magnetic model of the rotation curve of spiral galaxies. Once the disc had formed and acquired its present structure, approximately, three balanced forces were acting on the initial gas: gravity and magnetic forces, inwards, and

  16. Spontaneous and complete regression of a thoracic disc herniation

    International Nuclear Information System (INIS)

    Coevoet, V.; Benoudiba, F.; Doyon, D.; Lignieres, C.; Said, G.

    1997-01-01

    Spontaneous regression of disc herniation is well known but the mechanism is not clear. Some hypotheses have been made. We present here a large thoracic disc herniation diagnosed by MRI which completely regressed one year after a medical treatment with complete amendment of symptoms. (authors)

  17. Comparative Study on The Potency of Antibiotic Discs With ...

    African Journals Online (AJOL)

    Our results showed that antibiotics disc was more effective than the commercially sold antibiotics and that both organisms were resistant to Ampicillin but susceptible to Gentamicin and. Ciprofloxacin. Keywords: Potency, Antibiotics, Disc Isolates, Urinary tract. INTRODUCTION. The urinary system is structured in a way that.

  18. Delivery systems for the treatment of degenerated intervertebral discs

    NARCIS (Netherlands)

    Blanquer, S. B. G.; Grijpma, D. W.; Poot, A. A.

    The intervertebral disc (ND) is the most avascular and acellular tissue in the body and therefore prone to degeneration. During IVD degeneration, the balance between anabolic and catabolic processes in the disc is deregulated, amongst others leading to alteration of extracellular matrix production,

  19. Assembling Modules to the End-cap SCT Discs

    CERN Document Server

    Jackson, JN; Sutcliffe, P

    2002-01-01

    A major step in the construction of the SCT end-caps is the process of mounting the modules onto the discs and testing them. This note contains a description of the proposed assembly procedure and the design of the necessary jig to assemble inner, middle, and outer modules to the end-cap disc structure. Results obtained using prototype jigs are described.

  20. Optic Disc Coloboma in Two Nigerian Siblings: Case Report and ...

    African Journals Online (AJOL)

    with inferior disc excavation, superior wedge of the pink neuro‑retinal rim as well as a temporal optic disc pit. No systemic features of syndromes associated with. ODCs and intellectual disability were present in both patients. The younger sibling an 8‑year‑old girl later presented to the eye clinic with a 5‑month history of poor.

  1. Spine imaging after lumbar disc replacement: pitfalls and current recommendations

    OpenAIRE

    Robinson, Yohan; Sand?n, Bengt

    2009-01-01

    Abstract Background Most lumbar artificial discs are still composed of stainless steel alloys, which prevents adequate postoperative diagnostic imaging of the operated region when using magnetic resonance imaging (MRI). Thus patients with postoperative radicular symptoms or claudication after stainless steel implants often require alternative diagnostic procedures. Methods Possible complications of lumbar total disc replacement (TDR) are reviewed from the available literature and imaging reco...

  2. Tissue Engineering a Biological Repair Strategy for Lumbar Disc Herniation

    Science.gov (United States)

    O'Connell, Grace D.; Leach, J. Kent; Klineberg, Eric O.

    2015-01-01

    Abstract The intervertebral disc is a critical part of the intersegmental soft tissue of the spinal column, providing flexibility and mobility, while absorbing large complex loads. Spinal disease, including disc herniation and degeneration, may be a significant contributor to low back pain. Clinically, disc herniations are treated with both nonoperative and operative methods. Operative treatment for disc herniation includes removal of the herniated material when neural compression occurs. While this strategy may have short-term advantages over nonoperative methods, the remaining disc material is not addressed and surgery for mild degeneration may have limited long-term advantage over nonoperative methods. Furthermore, disc herniation and surgery significantly alter the mechanical function of the disc joint, which may contribute to progression of degeneration in surrounding tissues. We reviewed recent advances in tissue engineering and regenerative medicine strategies that may have a significant impact on disc herniation repair. Our review on tissue engineering strategies focuses on cell-based and inductive methods, each commonly combined with material-based approaches. An ideal clinically relevant biological repair strategy will significantly reduce pain and repair and restore flexibility and motion of the spine. PMID:26634189

  3. Demographical Aspects of Central Large Lumbar Disc Herniation.

    Science.gov (United States)

    Topuz, Kivanc; Eroglu, Ahmet; Simsek, Hakan; Atabey, Cem; Cetinkal, Ahmet; Colak, Ahmet

    2016-01-01

    The purpose of this study was to investigate the risk factors for the development of the central large disc herniations and to compare the demographic data between central mass prolapse and broad-based central disc herniation. Between 2002 and 2007, 1630 patients underwent surgery and a large disc herniation was the main problem in 59 patients (3.6%). We performed a retrospective analysis of the demographic data of these patients. Magnetic resonance (MR) images were evaluated according to the disc type and level. Variables were evaluated both at baseline and follow-up, with special emphasis on physical job characteristics, sports activities, and MR - based morphologic findings. Central large disc herniation was diagnosed in 59 patients consisting of 41 males and 18 females. The average age was 34.7 years. 36 patients had a central mass prolapse that occupied more than 50% of the spinal canal. Intraoperative observations confirmed that 29 out of 36 central disc prolapse patients (80.5%) had intact posterior longitudinal ligaments. Interestingly, the condition in these 29 patients was found to have a direct relation with age and occupation or other body training sports activities. The size of the large central disc herniation, physical activity, age and gender are major factors in the development of disc herniation.

  4. Spontaneous regression of lumbar herniated disc Case presentation

    Directory of Open Access Journals (Sweden)

    Chiriac A.

    2015-12-01

    Full Text Available Intervertebral disc herniation is a common disease that usually requires surgical intervention. However, in some cases, neurological symptoms may improve with conservative treatment. In this article, we present a case with spontaneous regression of extruded lumbar herniated disc correlated with clinical improvement and documented with follow up MRI studies.

  5. Surgical treatment of foraminal herniated disc of the lumbar spine

    OpenAIRE

    Halikov Shavkatbek; Abduhalikov Alimjon Karimjanovich

    2017-01-01

    Herniated lumbar intervertebral disc have a significant impact on both the patient’s life as well, and because of the high prevalence and economic impact on society as a whole. Designed scheduling algorithm foraminal hernia surgical treatment of lumbar intervertebral disc, based on the preoperative detection of compressing factors allows to define differentiated indications for decompressive or decompressive-stabilizing surgery.

  6. Disc Activities in Physical Education: A Comprehensive Approach

    Science.gov (United States)

    Cramer, Stanley J.

    2017-01-01

    Nearly everyone who throws a disc associates the activity with fun. Over the years, multiple disc games and activities have been invented, combining fun and learning. These are games that many individuals are likely to continue playing long after they have left school and are worthy of being included in a contemporary physical education program.…

  7. 21 CFR 872.3970 - Interarticular disc prosthesis (interpositional implant).

    Science.gov (United States)

    2010-04-01

    ... implant). 872.3970 Section 872.3970 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES DENTAL DEVICES Prosthetic Devices § 872.3970 Interarticular disc prosthesis (interpositional implant). (a) Identification. An interarticular disc prosthesis...

  8. Spectral properties of the accretion discs around rotating black holes

    Indian Academy of Sciences (India)

    Samir Mandal

    2018-02-10

    Feb 10, 2018 ... Abstract. We study the radiation properties of an accretion disc around a rotating black hole. We solve the hydrodynamic equations and calculate the transonic solutions of accretion disc in the presence of shocks. Then we use these solutions to generate the radiation spectrum in the presence of radiative ...

  9. Goddard Earth Science Data and Information Center (GES DISC)

    Science.gov (United States)

    Kempler, Steve

    2016-01-01

    The GES DIS is one of 12 NASA Earth science data centers. The GES DISC vision is to enable researchers and educators maximize knowledge of the Earth by engaging in understanding their goals, and by leading the advancement of remote sensing information services in response to satisfying their goals. This presentation will describe the GES DISC approach, successes, challenges, and best practices.

  10. Microfabrication and Magnetic Particle Spectrometry of Magnetic Discs

    NARCIS (Netherlands)

    Löthman, Per Arvid; Janson, T.G.; Klein, Yannick Philippe; Blaudszun, André-René; Ledwig, Michael; Abelmann, Leon

    2017-01-01

    We report on the fabrication of dispersions of Au/Ni81Fe19/Au magnetic discs with two and three micrometer diameter and thickness in the order of hundred nanometers. The magnetisation reversal of the discs was analysed on a time-scale of an hour as well as a few milliseconds to asses their

  11. Presumed optic disc melanocytoma in a young Nigerian: a ...

    African Journals Online (AJOL)

    Optic disc melanocytoma (ODM) is a rare, benign, deeply pigmented ocular tumor arising from melanocytes within the optic disc or from any part of the uvea. It occurs more in dark skinned individuals and females. We report a 17‑year‑old female who presented to our outpatient department with a history of poor distant vision ...

  12. CT-discography; diagnostic accuracy in lumbar disc herniation and significance of induced pain during procedure

    Energy Technology Data Exchange (ETDEWEB)

    Jin, En Hao [Yan Bian Medical College, Beijing (China); Chung, Tae Sub; Jeong, Mi Gyoung; Kim, Young Soo; Roh, Sung Woo [Yonsei Univ. College of Medicine, Seoul (Korea, Republic of)

    1996-01-01

    To evaluate the usefulness and the accuracy of CT-discography in lumbar disc disease by analyzing the findings of CT-discogram and types of evoked pain during the procedure. CT-discograms were retrospectively evaluated in 47 intervertebral discs of 20 patients with multilevel involvement of lumbar disc diseases. In 28 herniated discs confirmed at surgery, the findings of CT-discogram (28 disc levels/20 patients), MRI(23/16) and CT(21/15) were comparatively analysed. The type of pain after infusion of contrast media during CT-discography was compared with that prior to the procedure. The accuracy for determining types of the herniated lumbar disc when compared with post-operative results was 96.4%(27 discs/28 discs) in the CT-discogram, 82.6%(19 discs/23 discs) in MRI and 71.4%(15 discs/21 discs) in the CT scan. Pains encountered during discography were radiating pain in 12 discs and back pain in 24 discs. CT-discography was especially helpful in 10 patients with multilevel involvement of the lumbar disc diseases to evaluate the exact location of diseased disc(s) that provoked the pain. CT-discography is a highly accurate method in diagnosis of the herniated lumbar intervertebral discs and is very useful in determining the precise location related to the development of pain in such cases.

  13. The value of MRI in the preoperative diagnosis of cervical disc herniation

    Energy Technology Data Exchange (ETDEWEB)

    Kuroki, Takefusa; Kumano, Kiyoshi; Hirabayashi, Shigeru; Takahashi, Ryuji; Inasaka, Riki (Kanto Rosai Hospital, Tokyo (Japan))

    1991-12-01

    To determine whether or not magnetic resonance (MR) imaging would become an alternative to conventional myelography in the preoperative diagnosis of cervical disc herniation, MR images of 13 patients were retrospectively reviewed. MR imaging revealed herniated one disc, 2 discs, and 3 discs in 4, 6, and 3 patients, respectively. When herniation confined to one disc was consistent with clinical manifestations, MR imaging alone was capable of determining the disc involved in herniation. MR imaging was, however, of limited value in determining the responsible disc for herniation when there were two or more herniated discs on MR images. (N.K.).

  14. Magnetic resonance imaging for each type of herniated cervical intervertebral disc

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Ham Gyum [Ansan 1 College, Ansan (Korea, Republic of)

    2000-04-15

    The classification of herniated intervertebral cervical disc types are clinically important, as treatment methods would be slightly different according to the specific type of the herniated disc. 423 patients who suffered from herniated intervertebral cervical discs were tested with Magnetic Resonance Imaging (MRI), to distinguish the type of the herniated discs. The following are the results: The age of the patients tested ranged from 16 to 75 years old and the mean age of the patients was 41.4 years of age. There were twice as many male patients with a ratio of 288: 135 men to women. 101 patients suffered from single herniated discs while 322 patients suffered from multi-herniated discs. Of single herniated disc injuries. 52 patients had protruded discs (52%) while 25 patients had extruded discs (25%). 21 Patients (21%) had herniated intervertebral discs between C{sub 4} {approx} C{sub 5} and 51 patients (50%) and had the same injury between C{sub 5} and C{sub 6}. Of multi-herniated disc injuries. 140 patients had protruded discs (44%). while 45 patients had extruded discs (14%). 54 patients had both protruded and extruded discs (17%). 36 patients (11%). herniated discs C{sub 3} {approx} C{sub 6}: 69 patients (21%). herniated discs C{sub 3} {approx} C{sub 7}: 47 patients (15%) herniated discs C{sub 4} {approx} C{sub 6} and 67 patients (20%) herniated discs C{sub 5} {approx} C{sub 7}.

  15. CT-discography; diagnostic accuracy in lumbar disc herniation and significance of induced pain during procedure

    International Nuclear Information System (INIS)

    Jin, En Hao; Chung, Tae Sub; Jeong, Mi Gyoung; Kim, Young Soo; Roh, Sung Woo

    1996-01-01

    To evaluate the usefulness and the accuracy of CT-discography in lumbar disc disease by analyzing the findings of CT-discogram and types of evoked pain during the procedure. CT-discograms were retrospectively evaluated in 47 intervertebral discs of 20 patients with multilevel involvement of lumbar disc diseases. In 28 herniated discs confirmed at surgery, the findings of CT-discogram (28 disc levels/20 patients), MRI(23/16) and CT(21/15) were comparatively analysed. The type of pain after infusion of contrast media during CT-discography was compared with that prior to the procedure. The accuracy for determining types of the herniated lumbar disc when compared with post-operative results was 96.4%(27 discs/28 discs) in the CT-discogram, 82.6%(19 discs/23 discs) in MRI and 71.4%(15 discs/21 discs) in the CT scan. Pains encountered during discography were radiating pain in 12 discs and back pain in 24 discs. CT-discography was especially helpful in 10 patients with multilevel involvement of the lumbar disc diseases to evaluate the exact location of diseased disc(s) that provoked the pain. CT-discography is a highly accurate method in diagnosis of the herniated lumbar intervertebral discs and is very useful in determining the precise location related to the development of pain in such cases

  16. ac spin-Hall effect

    International Nuclear Information System (INIS)

    Entin-Wohlman, O.

    2005-01-01

    Full Text:The spin-Hall effect is described. The Rashba and Dresselhaus spin-orbit interactions are both shown to yield the low temperature spin-Hall effect for strongly localized electrons coupled to phonons. A frequency-dependent electric field E(ω) generates a spin-polarization current, normal to E, due to interference of hopping paths. At zero temperature the corresponding spin-Hall conductivity is real and is proportional to ω 2 . At non-zero temperatures the coupling to the phonons yields an imaginary term proportional to ω. The interference also yields persistent spin currents at thermal equilibrium, at E = 0. The contributions from the Dresselhaus and Rashba interactions to the interference oppose each other

  17. Design of an Annular Disc Subject to Thermomechanical Loading

    Directory of Open Access Journals (Sweden)

    Sergei Alexandrov

    2012-01-01

    Full Text Available Two solutions to design a thin annular disc of variable thickness subject to thermomechanical loading are proposed. It is assumed that the thickness of the disc is everywhere sufficiently small for the stresses to be averaged through the thickness. The state of stress is plane. The initiation of plastic yielding is controlled by Mises yield criterion. The design criterion for one of the solutions proposed requires that the distribution of stresses is uniform over the entire disc. In this case there is a relation between optimal values of the loading parameters at the final stage. The specific shape of the disc corresponds to each pair of such parameters. The other solution is obtained under the additional requirement that the distribution of strains is uniform. This solution exists for the disc of constant thickness at specific values of the loading parameters.

  18. The radiological diagnosis of thoracolumbar disc disease in the Dachshund

    International Nuclear Information System (INIS)

    Kirberger, R.M.; Roos, C.J.; Lubbe, A.M.

    1992-01-01

    The accuracy of survey radiographs in the diagnosis of acute thoracolumbar disc disease in 36 Dachshunds was determined by comparison with lumbar myelographic findings using iohexol. The value of making radiographs immediately after injection of contrast medium and the effectiveness of oblique radiographs in determining the exact circumferential distribution of extruding or protruding disc material were assessed. The presence of a double contrast medium column, resistance to injection and the presence of cerebrospinal fluid flow during needle placement was also evaluated. The location of the affected disc was accurately determined on survey radiographs in only 26 dogs. The myelographic technique used in this study resulted in the correct intervertebral space being identified, together with the exact circumferential distribution of disc material, in 35 dogs. Survey radiographs alone are inadequate for localization of protruding or extruding disc material

  19. Observation of the spin Nernst effect

    Science.gov (United States)

    Meyer, S.; Chen, Y.-T.; Wimmer, S.; Althammer, M.; Wimmer, T.; Schlitz, R.; Geprägs, S.; Huebl, H.; Ködderitzsch, D.; Ebert, H.; Bauer, G. E. W.; Gross, R.; Goennenwein, S. T. B.

    2017-10-01

    The observation of the spin Hall effect triggered intense research on pure spin current transport. With the spin Hall effect, the spin Seebeck effect and the spin Peltier effect already observed, our picture of pure spin current transport is almost complete. The only missing piece is the spin Nernst (-Ettingshausen) effect, which so far has been discussed only on theoretical grounds. Here, we report the observation of the spin Nernst effect. By applying a longitudinal temperature gradient, we generate a pure transverse spin current in a Pt thin film. For readout, we exploit the magnetization-orientation-dependent spin transfer to an adjacent yttrium iron garnet layer, converting the spin Nernst current in Pt into a controlled change of the longitudinal and transverse thermopower voltage. Our experiments show that the spin Nernst and the spin Hall effect in Pt are of comparable magnitude, but differ in sign, as corroborated by first-principles calculations.

  20. Symplectic integrators for spin systems

    Science.gov (United States)

    McLachlan, Robert I.; Modin, Klas; Verdier, Olivier

    2014-06-01

    We present a symplectic integrator, based on the implicit midpoint method, for classical spin systems where each spin is a unit vector in R3. Unlike splitting methods, it is defined for all Hamiltonians and is O (3)-equivariant, i.e., coordinate-independent. It is a rare example of a generating function for symplectic maps of a noncanonical phase space. It yields a new integrable discretization of the spinning top.

  1. Asymptotics of relativistic spin networks

    International Nuclear Information System (INIS)

    Barrett, John W; Steele, Christopher M

    2003-01-01

    The stationary phase technique is used to calculate asymptotic formulae for SO(4) relativistic spin networks. For the tetrahedral spin network this gives the square of the Ponzano-Regge asymptotic formula for the SU(2) 6j-symbol. For the 4-simplex (10j-symbol) the asymptotic formula is compared with numerical calculations of the spin network evaluation. Finally, we discuss the asymptotics of the SO(3, 1) 10j-symbol

  2. Spin currents in metallic nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Czeschka, Franz Dominik

    2011-09-05

    A pure spin current, i.e., a flow of angular momentum without accompanying net charge current, is a key ingredient in the field of spintronics. In this thesis, we experimentally investigated two different concepts for pure spin current sources suggested by theory. The first is based on a time-dependent magnetization precession which ''pumps'' a pure spin current into an adjacent non-magnetic conductor. Our experiments quantitatively corroborated important predictions expected theoretically for this approach, including the dependence of the spin current on the sample geometry and the microwave power. Even more important, we could show for the first time that the spin pumping concept is viable in a large variety of ferromagnetic materials and that it only depends on the magnetization damping. Therefore, our experiments established spin pumping as generic phenomenon and demonstrated that it is a powerful way to generate pure spin currents. The second theoretical concept is based on the conversion of charge currents into spin currents in non-magnetic nanostructures via the spin Hall effect. We experimentally investigated this approach in H-shaped, metallic nanodevices, and found that the predictions are linked to requirements not realizable with the present experimental techniques, neither in sample fabrication nor in measurement technique. Indeed, our experimental data could be consistently understood by a spin-independent transport model describing the transition from diffusive to ballistic transport. In addition, the implementation of advanced fabrication and measurement techniques allowed to discover a new non-local phenomenon, the non-local anisotropic magnetoresistance. Finally, we also studied spin-polarized supercurrents carried by spin-triplet Cooper pairs. We found that low resistance interfaces are a key requirement for further experiments in this direction. (orig.)

  3. Gas Modelling in the Disc of HD 163296

    Science.gov (United States)

    Tilling, I.; Woitke, P.; Meeus, G.; Mora, A.; Montesinos, B.; Riviere-Marichalar, P.; Eiroa, C.; Thi, W. -F.; Isella, A.; Roberge, A.; hide

    2011-01-01

    We present detailed model fits to observations of the disc around the Herbig Ae star HD 163296. This well-studied object has an age of approx. 4Myr, with evidence of a circumstellar disc extending out to approx. 540AU. We use the radiation thermo-chemical disc code ProDiMo to model the gas and dust in the circumstellar disc of HD 163296, and attempt to determine the disc properties by fitting to observational line and continuum data. These include new Herschel/PACS observations obtained as part of the open-time key program GASPS (Gas in Protoplanetary Systems), consisting of a detection of the [Oi] 63 m line and upper limits for several other far infrared lines. We complement this with continuum data and ground-based observations of the CO-12 3-2, 2-1 and CO-13 J=1-0 line transitions, as well as the H2 S(1) transition. We explore the effects of stellar ultraviolet variability and dust settling on the line emission, and on the derived disc properties. Our fitting efforts lead to derived gas/dust ratios in the range 9-100, depending on the assumptions made. We note that the line fluxes are sensitive in general to the degree of dust settling in the disc, with an increase in line flux for settled models. This is most pronounced in lines which are formed in the warm gas in the inner disc, but the low excitation molecular lines are also affected. This has serious implications for attempts to derive the disc gas mass from line observations. We derive fractional PAH abundances between 0.007 and 0.04 relative to ISM levels. Using a stellar and UV excess input spectrum based on a detailed analysis of observations, we find that the all observations are consistent with the previously assumed disc geometry

  4. The presence and absence of lymphatic vessels in the adult human intervertebral disc: relation to disc pathology

    Energy Technology Data Exchange (ETDEWEB)

    Kliskey, Karolina; Williams, Kelly; Yu, J.; Urban, Jill; Athanasou, Nick [University of Oxford, Nuffield Department of Orthopaedic, Rheumatology and Musculoskeletal Science, Oxford (United Kingdom); Jackson, David [Weatherall Institute of Molecular Medicine, Human Immunology Unit, Oxford (United Kingdom)

    2009-12-15

    Although the normal adult human intervertebral disc is considered to be avascular, vascularised cellular fibrous tissue can be found in pathological conditions involving the disc such as disc herniation. Whether lymphatics vessels form a component of this reparative tissue is not known as the presence or absence of lymphatics in herniated and normal disc tissue is not known. We examined spinal tissues and discectomy specimens for the presence of lymphatics. The examination used immunohistochemistry to identify the specific lymphatic endothelial cell markers, podoplanin and LYVE1. Lymphatic vessels were not found in the nucleus pulposus or annulus fibrosus of intact, non-herniated lumbar and thoracic discs but were present in the surrounding ligaments. Ingrowth of fibrous tissue was seen in 73% of herniated disc specimens of which 36% contained LYVE1+/podoplanin + lymphatic vessels. Lymphatic vessels were not seen in the sacrum and coccyx or biopsies of four sacrococcygeal chordomas, but they were noted in surrounding extra-osseous fat and fibrous tissue at the edge of the infiltrating tumour. Our findings indicate that lymphatic vessels are not present in the normal adult intervertebral disc but that, when there is extrusion of disc material into surrounding soft tissue, there is ingrowth of reparative fibrous tissue containing lymphatic vessels. Our findings also indicate that chordoma, a tumour of notochordal origin, spreads to regional lymph nodes via lymphatics in para-spinal soft tissues. (orig.)

  5. Migration patterns of herniated disc fragments: a study on 1,020 patients with extruded lumbar disc herniation.

    Science.gov (United States)

    Daghighi, Mohammad Hussein; Pouriesa, Masoud; Maleki, Mirjalil; Fouladi, Daniel Fadaei; Pezeshki, Mohammad Zakaria; Mazaheri Khameneh, Ramin; Bazzazi, Amir Mohammad

    2014-09-01

    Herniated disc fragments are known to migrate in various directions within the spinal canal. To date, no comprehensive studies have been undertaken to examine the migration patterns of herniated disc material using a standard nomenclature and classification system. To report migration patterns of extruded lumbar disc fragments. A review of magnetic resonance (MR) images. A total of 1,020 consecutive Azeri patients with symptomatic extruded lumbar intervertebral disc herniation. Migration patterns of extruded lumbar disc fragments in vertical and horizontal planes and their association with age, gender, body mass index (BMI), and the level of herniation. High-quality axial and sagittal MR images of the lumbar spine were used. Disc material that was displaced away from the site of extrusion, regardless of continuity, was considered "migrated." The migration patterns observed were rostral or caudal in the vertical plane and central, paracentral, subarticular, foraminal, or extraforaminal in the horizontal plane. In the vertical plane, rostral and caudal migrations were observed in 27.8% and 72.2% of the patients, respectively. The number of rostral migrations increased significantly with increasing age and in higher levels in the lumbar spine (pherniation and migration pattern in the horizontal plane. Caudal and paracentral migrations are the most common patterns of migration in patients with extruded lumbar disc herniation in the vertical and horizontal planes, respectively. Age and the level of herniation may affect the migration patterns of herniated lumbar disc material. Copyright © 2014 Elsevier Inc. All rights reserved.

  6. Analysis of trace element in intervertebral disc by Atomic Absorption Spectrometry techniques in degenerative disc disease in the Polish population

    Directory of Open Access Journals (Sweden)

    Andrzej Nowakowski

    2015-05-01

    This study is the first to our knowledge that profiles the elements in intervertebral disc in patients with degenerative changes. We have confirmed significant differences between the trace element contents in intervertebral disc and other tissue. It can be ground for further investigation.

  7. The presence and absence of lymphatic vessels in the adult human intervertebral disc: relation to disc pathology

    International Nuclear Information System (INIS)

    Kliskey, Karolina; Williams, Kelly; Yu, J.; Urban, Jill; Athanasou, Nick; Jackson, David

    2009-01-01

    Although the normal adult human intervertebral disc is considered to be avascular, vascularised cellular fibrous tissue can be found in pathological conditions involving the disc such as disc herniation. Whether lymphatics vessels form a component of this reparative tissue is not known as the presence or absence of lymphatics in herniated and normal disc tissue is not known. We examined spinal tissues and discectomy specimens for the presence of lymphatics. The examination used immunohistochemistry to identify the specific lymphatic endothelial cell markers, podoplanin and LYVE1. Lymphatic vessels were not found in the nucleus pulposus or annulus fibrosus of intact, non-herniated lumbar and thoracic discs but were present in the surrounding ligaments. Ingrowth of fibrous tissue was seen in 73% of herniated disc specimens of which 36% contained LYVE1+/podoplanin + lymphatic vessels. Lymphatic vessels were not seen in the sacrum and coccyx or biopsies of four sacrococcygeal chordomas, but they were noted in surrounding extra-osseous fat and fibrous tissue at the edge of the infiltrating tumour. Our findings indicate that lymphatic vessels are not present in the normal adult intervertebral disc but that, when there is extrusion of disc material into surrounding soft tissue, there is ingrowth of reparative fibrous tissue containing lymphatic vessels. Our findings also indicate that chordoma, a tumour of notochordal origin, spreads to regional lymph nodes via lymphatics in para-spinal soft tissues. (orig.)

  8. Resolving HD 100546 disc in the mid-infrared: Small inner disc and asymmetry near the gap

    NARCIS (Netherlands)

    Panić, O.; Ratzka, T.; Mulders, G.D.; Dominik, C.; van Boekel, R.; Henning, T.; Jaffe, W.J.; Min, M.

    2014-01-01

    Context. A region of roughly half of the solar system scale around the star HD 100546 is known to be largely cleared of gas and dust, in contrast to the outer disc that extends to about 400 AU. However, some material is observed in the immediate vicinity of the star, called the inner disc. Studying

  9. Minimally invasive transmuscular approach for the treatment of lumbar herniated disc: far lateral lumbar disc herniation: a clinical study. Applications for cervical and thoracic disc herniation.

    Science.gov (United States)

    Peltier, E; Blondel, B; Dufour, H; Fuentes, S

    2013-06-01

    In this study, we are using a recently developed method: a minimally invasive retractor system and an operating microscope to treat far lateral lumbar herniated disc. This method decreases tissue dissection and blood loss, and improves postoperative recovery. This is a retrospective study of 46 patients, there was 25 female and 21 male. They all underwent minimal invasive surgery. The average age was 56 years old (19-83 years). Lumbar disc herniation is a common pathology. Far lateral disc herniation accounts for 2.6% to 11.2% of all lumbar disc herniation. A few surgical techniques have been describes to treat this type of disc pathology. All patients were operated under general anesthesia. The fluoroscopic guidance was absolutely necessary. A 12-15 mm skin incision was made on the side of the disc herniation (30 mm from the midline). Then, we inserted a tubular retractor system (muscle splitting approach) followed by a 14 mm diameter-working channel. Under operating microscope the pars interarticularis was dreamed to expose the nerve root and the disc. After removing the intertransverse ligament, we removed the herniated disc. The average time of surgery was 55 min. The operating time decreased with the experience of the surgical team. Postoperatively the radicular pain was around 2 (using an analogical visual scale), over 7 preoperatively. The length of hospitalization was 3 days. There were no complications in our study. The average follow-up was 2 years (6-36 months). There was no complication, no postoperative infection. This technique combines the advantages of endoscopic surgery and microscope guided surgery (3D vision) and provides good functional results in this study.

  10. Towards spin injection into silicon

    Energy Technology Data Exchange (ETDEWEB)

    Dash, S.P.

    2007-08-15

    Si has been studied for the purpose of spin injection extensively in this thesis. Three different concepts for spin injection into Si have been addressed: (1) spin injection through a ferromagnet-Si Schottky contact, (2) spin injection using MgO tunnel barriers in between the ferromagnet and Si, and (3) spin injection from Mn-doped Si (DMS) as spin aligner. (1) FM-Si Schottky contact for spin injection: To be able to improve the interface qualities one needs to understand the atomic processes involved in the formation of silicide phases. In order to obtain more detailed insight into the formation of such phases the initial stages of growth of Co and Fe were studied in situ by HRBS with monolayer depth resolution.(2) MgO tunnel barrier for spin injection into Si: The fabrication and characterization of ultra-thin crystalline MgO tunnel barriers on Si (100) was presented. (3) Mn doped Si for spin injection: Si-based diluted magnetic semiconductor samples were prepared by doping Si with Mn by two different methods i) by Mn ion implantation and ii) by in-diffusion of Mn atoms (solid state growth). (orig.)

  11. Spin-photon entangling diode

    DEFF Research Database (Denmark)

    Flindt, Christian; Sørensen, A. S.; Lukin, M. D.

    2007-01-01

    We propose a semiconductor device that can electrically generate entangled electron spin-photon states, providing a building block for entanglement of distant spins. The device consists of a p-i-n diode structure that incorporates a coupled double quantum dot. We show that electronic control...... of the diode bias and local gating allow for the generation of single photons that are entangled with a robust quantum memory based on the electron spins. Practical performance of this approach to controlled spin-photon entanglement is analyzed....

  12. Spin diffusion in Fermi gases

    DEFF Research Database (Denmark)

    Bruun, Georg

    2011-01-01

    We examine spin diffusion in a two-component homogeneous Fermi gas in the normal phase. Using a variational approach, analytical results are presented for the spin diffusion coefficient and the related spin relaxation time as a function of temperature and interaction strength. For low temperatures......, strong correlation effects are included through the Landau parameters which we extract from Monte Carlo results. We show that the spin diffusion coefficient has a minimum for a temperature somewhat below the Fermi temperature with a value that approaches the quantum limit ~/m in the unitarity regime...

  13. A new dynamic six degrees of freedom disc-loading simulator allows to provoke disc damage and herniation.

    Science.gov (United States)

    Wilke, Hans-Joachim; Kienle, Annette; Maile, Sebastian; Rasche, Volker; Berger-Roscher, Nikolaus

    2016-05-01

    The cause of disc herniation is not well understood yet. It is assumed that heavy lifting and extreme postures can cause small injuries starting either in the inner anulus or from the outside close to the endplate. Such injuries are accumulated over years until its structure is weakened and finally a single loading event leads to a sudden failure of the last few intact lamellae. This paper describes a novel, custom-developed dynamic 6-DOF disc-loading simulator that allows complex loading to provoke such disc damage and herniations. The machine's axes are driven by six independent servomotors providing high loads (10 kN axial compression, 2 kN shear, 100 Nm torque) up to 5 Hz. A positional accuracy test was conducted to validate the machine. Subsequently, initial experiments with lumbar ovine motion segments under complex loading were performed. After testing, the discs were examined in an ultra-high field MRI (11.7 T). A three-dimensional reconstruction was performed to visualise the internal disc lesions. Validation tests demonstrated positioning with an accuracy of ≤0.08°/≤0.026 mm at 0.5 Hz and ≤0.27°/≤0.048 mm at 3.0 Hz with amplitudes of ±17°/±2 mm. Typical failure patterns and herniations could be provoked with complex asymmetrical loading protocols. Loading with axial compression, flexion, lateral bending and torsion lead in 8 specimens to 4 herniated discs, two protrusions and two delaminations. All disc failures occurred in the posterior region of the disc. This new dynamic disc-loading simulator has proven to be able to apply complex motion combinations and allows to create artificial lesions in the disc with complex loading protocols. The aim of further tests is to better understand the mechanisms by which disc failure occurs at the microstructural level under different loading conditions. Visualisation with ultra-high field MRI at different time points is a promising method to investigate the gradual development of such lesions

  14. Electron spin resonance

    International Nuclear Information System (INIS)

    Wasson, J.R.; Salinas, J.E.

    1980-01-01

    Published literature concerning electron spin resonance (ESR) from July 1977 to July 1979 is reviewed. The 108 literature sources cited were chosen from literally thousands and are intended to serve as a guide to the current literature and to provide an eclectic selection of publications cited for their contributions to the advance and/or applications of ESR spectroscopy. 40 of the sources are reviews, and a table is included to indicate the topic(s) mainly covered in each review. Other divisions of the material reviewed are apparatus and spectral analysis, analytical applications, and selected paramagnetic materials

  15. Intraosseous disc prolapse: A diagnostic puzzle

    Directory of Open Access Journals (Sweden)

    Parasnis Rajesh

    2006-01-01

    Full Text Available Background : Schmorl′s node or intraosseous disc prolapse is herniation of the nucleus pulposus material through the vertebral end plates. Presence of Schmorl′s nodes as end plate lesions following trauma, tumours and osteoporosis further complicates diagnosis. The present study was done to understand diagnosis and approach to management of symptomatic Schmorl′s nodes. Methods : During a period of three years we came across 14 patients who presented with severe back pain. Conventional radiographs, CT Scans and MRI showed the presence of end plate lesions with varied radiological appearance. The first group, comprising of seven patients had lytic lesions without any sclerosis on only one side of the intervertebral disc as seen on the CT scan. The second group comprising of five patients had sclerotic lesions with new bone formation associated with disc space reduction. The two patients in the third group showed a combined lytic and sclerotic lesion without any soft tissue changes. MRI of eleven patients revealed hypointense lesion on T 1 and T 2 weighted images with surrounding zone of hyper intensity on T 2 weighted images. The remaining three patients, did not have this hyper intense zone on T 2 weighted images . In five patients multiple Schmorl′s nodes were observed. Diagnosis of symptomatic Schmorl′s nodes was mainly done by exclusion. All patients were given rest and anti-inflammatory drugs followed by exercises. Results : The first two groups of patients responded to the treatment and had complete relief of symptoms but both the patients in third group had persistent symptoms. MRI repeated after eight weeks showed an enhancing lesion with prevertebral soft tissue. A transpedicular core biopsy proved the lesion to be tuberculosis in one patient. Anti Koch′s therapy was promptly started and follow up study showed resolution of the lesions. At the end of the study period all the patients were asymptomatic and returned to their

  16. Genetic Alterations in Intervertebral Disc Disease

    Directory of Open Access Journals (Sweden)

    Nikolay L. Martirosyan

    2016-11-01

    Full Text Available Background: Intervertebral disc degeneration (IVDD is considered a multifactorial disease. The last two decades of research strongly demonstrate that genetic factors contribute about 75% of the IVDD etiology. Recent total genome sequencing studies have shed light on the various single nucleotide polymorphisms (SNPs that are associated with IVDD.Aim: This review explores and presents updated information about the diversity of genetic factors in the inflammatory, degradative, homeostatic, and structural systems involved in the IVDD.Results: SNPs in the genes coding for structural proteins linked with IVDD or disc bulging include the Sp1 polymorphism of COL1A1, Trp3 polymorphism of COL9A3, several polymorphisms of COL11A1 and COL11A2, and a variable number tandem repeat polymorphism of ACAN. The rs4148941 SNP of CHST3 coding for an aggrecan sulfation enzyme is also associated with IVDD. The FokI, TaqI, and ApaI SNPs of the vitamin D receptor gene that is involved in chondrocyte functioning are also associated with IVDD. SNPs relevant to cytokine imbalance in IVDD include 889C/T of IL1a and 15T/A, as well as other SNPs (rs1800795, rs1800796, and rs1800797, of IL6, with effects limited to certain genders and populations. SNPs in collagenase genes include -1605G/D (guanine insertion/deletion of MMP1, -1306C/T of MMP2, -1562C/T and a 5-adenosine (5A variant (in the promotor region of MMP3, -1562C/T of MMP9, and -378T/C of MMP-14. SNPs in aggrecanase genes include 1877T/U of ADAMTS-4 and rs162509 of ADAMTS-5. Among the apoptosis-mediating genes, 1595T/C of the caspase 9 gene, 1525A/G and 1595T/C of the TRAIL gene, and 626C/G of the death receptor 4 gene (DR4 are SNPs associated with IVDD. Among the growth factors involved in disc homeostasis, the rs4871857 SNP of GDF5 was associated with IVDD. VEGF SNPs -2578C/A and -634G/C could foster neovascularization observed in IVDD.Conclusion: Improved understanding of the numerous genetic variants behind various

  17. Angular dependence of spin-orbit spin-transfer torques

    KAUST Repository

    Lee, Ki-Seung

    2015-04-06

    In ferromagnet/heavy-metal bilayers, an in-plane current gives rise to spin-orbit spin-transfer torque, which is usually decomposed into fieldlike and dampinglike torques. For two-dimensional free-electron and tight-binding models with Rashba spin-orbit coupling, the fieldlike torque acquires nontrivial dependence on the magnetization direction when the Rashba spin-orbit coupling becomes comparable to the exchange interaction. This nontrivial angular dependence of the fieldlike torque is related to the Fermi surface distortion, determined by the ratio of the Rashba spin-orbit coupling to the exchange interaction. On the other hand, the dampinglike torque acquires nontrivial angular dependence when the Rashba spin-orbit coupling is comparable to or stronger than the exchange interaction. It is related to the combined effects of the Fermi surface distortion and the Fermi sea contribution. The angular dependence is consistent with experimental observations and can be important to understand magnetization dynamics induced by spin-orbit spin-transfer torques.

  18. Diffusion equation and spin drag in spin-polarized transport

    DEFF Research Database (Denmark)

    Flensberg, Karsten; Jensen, Thomas Stibius; Mortensen, Asger

    2001-01-01

    We study the role of electron-electron interactions for spin-polarized transport using the Boltzmann equation, and derive a set of coupled transport equations. For spin-polarized transport the electron-electron interactions are important, because they tend to equilibrate the momentum of the two-s...

  19. Different Expression of Extracellular Matrix Genes : Primary vs. Recurrent Disc Herniation

    Science.gov (United States)

    Kuh, Sung-Uk; Kwon, Young-Min; Chin, Dong-Kyu; Jin, Byung-Ho; Cho, Yong-Eun

    2010-01-01

    Objective Recurrent lumbar disc herniation has been reported to occur in 5% to 15% of surgically treated primary lumbar disc herniation cases. We investigated the molecular biologic characteristics of primary herniated discs and recurrent discs to see whether the recurrent discs has the similar biological features with primary herniated discs. Methods Primary herniated disc and recurrent disc cells were obtained by discectomy of lumbar disc patients and cells were isolated and then taken through monolayer cultures. We compared chondrogenic and osteogenic mRNA gene expression, and western blot between the two groups. Results The mRNA gene expression of recurrent disc cells were increased 1.47* times for aggrecan, 1.38 times for type I collagen, 2.04 times for type II collagen, 1.22 times for both Sox-9 and osteocalcin, and 1.31 times for alkaline phosphatase, respectively, compared with the primary herniated lumbar disc cells (*indicates p herniated disc cells and recurrent disc cells. Conclusion These results indicate that the recurrent disc cells have similar chondrogenic and osteogenic gene expression compared to primary herniated disc cells. Therefore, we assumed that the regeneration of remaining discs could fill the previous discectomy space and also it could be one of the factors for disc recurrence especially in the molecular biologic field. PMID:20157374

  20. Metrical analysis of disc-condyle relation with different splint treatment positions in patients with TMJ disc displacement

    Directory of Open Access Journals (Sweden)

    Mu-Qing Liu

    Full Text Available Abstract Objective: To evaluate the effect of bite positions characterizing different splint treatments (anterior repositioning and stabilization splints on the disc-condyle relation in patients with TMJ disc displacement with reduction (DDwR, using magnetic resonance imaging (MRI. Material and Methods: 37 patients, with a mean age of 18.8±4.3 years (7 male and 30 females and diagnosed with DDwR based on the RDC/TMD, were recruited. MRI metrical analysis of the spatial changes of the disc/condyle, as well as their relationships, was done in three positions: maximum intercuspation (Position 1, anterior repositioning splint position (Position 2, and stabilization splint position (Position 3. Disc/condyle coordinate measurements and disc condyle angles were determined and compared. Results: In Position 1, the average disc-condyle angle was 53.4° in the 60 joints with DDwR, while it was −13.3° with Position 2 and 30.1° with Position 3. The frequency of successful "disc recapture" with Position 2 was significantly higher (58/60, 96.7% than Position 3 (20/60, 33.3%. In Positions 2 and 3, the condyle moved forward and downward while the disc moved backward. The movements were, however, more remarkable with Position 2. Conclusions: Anterior repositioning of the mandible improves the spatial relationship between the disc and condyle in patients with DDwR. In addition to anterior and inferior movement of the condyle, transitory posterior movement of the disc also occurred.