Science.gov

Sample records for radial forces derived

  1. Parachute drag and radial force

    SciTech Connect

    Purvis, J.W.

    1986-01-01

    This paper presents a combination of old and new wind tunnel data in a format which illustrates the effects of inflated diameter, geometric porosity, reefing line length, suspension line length, number of gores, and number of ribbons on parachute drag. A new definition of radial force coefficient is presented, as well as a universal drag curve for flat circular and conical parachutes.

  2. Radial forces within muscle fibers in rigor.

    PubMed

    Maughan, D W; Godt, R E

    1981-01-01

    Considering the widely accepted cross-bridge model of muscle contraction (Huxley. 1969. Science [Wash. D. C.]. 164:1356-1366), one would expect that attachment of angled cross-bridges would give rise to radial as well as longitudinal forces in the muscle fiber. These forces would tend, in most instances, to draw the myofilaments together and to cause the fiber to decrease in width. Using optical techniques, we have observed significant changes in the width of mechanically skinned frog muscle fibers when the fibers are put into rigor by deleting ATP from the bathing medium. Using a high molecular weight polymer polyvinylpyrrolidone (PVP-40; number average mol. wt. (Mn) = 40,000) in the bathing solution, we were able to estimate the magnitude of the radial forces by shrinking the relaxed fiber to the width observed with rigor induction. With rigor, fiber widths decreased up to approximately 10%, with shrinking being greater at shorter sarcomere spacing and at lower PVP concentrations. At higher PVP concentrations, some fibers actually swelled slightly. Radial pressures seen with rigor in 2 and 4% PVP ranged up to 8.9 x 10(3) N/m2. Upon rigor induction, fibers exerted a longitudinal force of approximately 1 x 10(5) N/m2 that was inhibited by high PVP concentrations (greater than or equal to 13%). In very high PVP concentrations (greater than or equal to 20%), fibers exerted an anomalous force, independent of ATP, which ranged up to 6 x 10(4) N/m2 at 60% PVP. Assuming that all the radial force is the result of cross-bridge attachment, we calculated that rigor cross-bridges exert a radial force of 0.2 x 1.2 x 10(-9) N per thick filament in sarcomeres near rest length. This force is of roughly the same order of magnitude as the longitudinal force per thick filament in rigor contraction or in maximal (calcium-activated) contraction of skinned fibers in ATP-containing solutions. Inasmuch as widths of fibers stretched well beyond overlap of thick and thin filaments

  3. Geometric Derivation of Radial Acceleration Magnitude.

    ERIC Educational Resources Information Center

    Kraft, David W.; Motz, Lloyd

    1995-01-01

    Standard treatments of uniform circular motion generally employ a combination of geometric and kinematic arguments to obtain the magnitude of radial acceleration. Presents a novel approach to the geometric portion of the derivation that uses the property that vectors can be translated parallel to themselves. (JRH)

  4. Radial forces analysis and rotational speed test of radial permanent magnetic bearing for horizontal axis wind turbine applications

    NASA Astrophysics Data System (ADS)

    Kriswanto, Jamari

    2016-04-01

    Permanent magnet bearings (PMB) are contact free bearings which utilize the forces generated by the magnets. PMB in this work is a type of radial PMB, which functions as the radial bearings of the Horizontal Axis Wind Turbine (HAWT) rotor shaft. Radial PMB should have a greater radial force than the radial force HAWT rotor shaft (bearing load). This paper presents a modeling and experiments to calculate the radial force of the radial PMB. This paper also presents rotational speed test of the radial PMB compared to conventional bearings for HAWT applications. Modeling using COMSOL Multiphysics 4.3b with the magnetic fields physics models. Experiments were conducted by measuring the displacement of the rotor to the stator for a given load variation. Results of the two methods showed that the large displacement then the radial force would be greater. Radial forces of radial PMB is greater than radial forces of HAWT rotor shaft. The rotational speed test results of HAWT that used radial PMB produced higher rotary than conventional bearings with an average increase of 87.4%. Increasing rotational speed occured because radial PMB had no friction. HAWT that used radial PMB rotated at very low wind speeds are 1.4 m/s with a torque of 0.043 Nm, while the HAWT which uses conventional bearing started rotating at a wind speed of 4.4 m/s and required higher torque of 0.104 N.

  5. Estimation of the radial force on the tokamak vessel wall during fast transient events

    SciTech Connect

    Pustovitov, V. D.

    2016-11-15

    The radial force balance in a tokamak during fast transient events with a duration much shorter than the resistive time of the vacuum vessel wall is analyzed. The aim of the work is to analytically estimate the resulting integral radial force on the wall. In contrast to the preceding study [Plasma Phys. Rep. 41, 952 (2015)], where a similar problem was considered for thermal quench, simultaneous changes in the profiles and values of the pressure and plasma current are allowed here. Thereby, the current quench and various methods of disruption mitigation used in the existing tokamaks and considered for future applications are also covered. General formulas for the force at an arbitrary sequence or combination of events are derived, and estimates for the standard tokamak model are made. The earlier results and conclusions are confirmed, and it is shown that, in the disruption mitigation scenarios accepted for ITER, the radial forces can be as high as in uncontrolled disruptions.

  6. Analyses of hydrodynamic radial forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Adkins, D. R.; Brennen, C. E.

    1988-01-01

    An experimental and theoretical study of the hydrodynamic interactions occurring between a centrifugal pump impeller and a volute is presented. The theoretical analysis provides a quasi-one-dimensional treatment of the flow in the volute, and it is extended to include the hydrodynamic force perturbations caused by the impeller whirling eccentrically in the volute. It is noted that these perturbations are often destabilizing. The theoretical models were found to accurately predict the radial forces caused by the flow through the impeller. The pressure acting on the front shroud of the impeller is shown to have a significant effect on the destabilizing hydrodyamic forces.

  7. Analyses of hydrodynamic radial forces on centrifugal pump impellers

    NASA Technical Reports Server (NTRS)

    Adkins, D. R.; Brennen, C. E.

    1988-01-01

    An experimental and theoretical study of the hydrodynamic interactions occurring between a centrifugal pump impeller and a volute is presented. The theoretical analysis provides a quasi-one-dimensional treatment of the flow in the volute, and it is extended to include the hydrodynamic force perturbations caused by the impeller whirling eccentrically in the volute. It is noted that these perturbations are often destabilizing. The theoretical models were found to accurately predict the radial forces caused by the flow through the impeller. The pressure acting on the front shroud of the impeller is shown to have a significant effect on the destabilizing hydrodyamic forces.

  8. Radial force development during root growth measured by photoelasticity

    NASA Astrophysics Data System (ADS)

    Kolb, Evelyne; Hartmann, Christian; Genet, Patricia

    2012-02-01

    The mechanical and topological properties of a soil like the global porosity and the distribution of void sizes greatly affect the development of a plant root, which in turn affects the shoot development. In particular, plant roots growing in heterogeneous medium like sandy soils or cracked substrates have to adapt their morphology and exert radial forces depending on the pore size in which they penetrate. We propose a model experiment in which a pivot root (chick-pea seeds) of millimetric diameter has to grow in a size-controlled gap δ (δ ranging 0.5-2.3 mm) between two photoelastic grains. By time-lapse imaging, we continuously monitored the root growth and the development of optical fringes in the photoelastic neighbouring grains when the root enters the gap. Thus we measured simultaneously and in situ the root morphological changes (length and diameter growth rates, circumnutation) as well as the radial forces the root exerts. Radial forces were increasing in relation with gap constriction and experiment duration but a levelling of the force was not observed, even after 5 days and for narrow gaps. The inferred mechanical stress was consistent with the turgor pressure of compressed cells. Therefore our set-up could be a basis for testing mechanical models of cellular growth.

  9. Radial forcing and Edgar Allan Poe's lengthening pendulum

    NASA Astrophysics Data System (ADS)

    McMillan, Matthew; Blasing, David; Whitney, Heather M.

    2013-09-01

    Inspired by Edgar Allan Poe's The Pit and the Pendulum, we investigate a radially driven, lengthening pendulum. We first show that increasing the length of an undriven pendulum at a uniform rate does not amplify the oscillations in a manner consistent with the behavior of the scythe in Poe's story. We discuss parametric amplification and the transfer of energy (through the parameter of the pendulum's length) to the oscillating part of the system. In this manner, radial driving can easily and intuitively be understood, and the fundamental concept applied in many other areas. We propose and show by a numerical model that appropriately timed radial forcing can increase the oscillation amplitude in a manner consistent with Poe's story. Our analysis contributes a computational exploration of the complex harmonic motion that can result from radially driving a pendulum and sheds light on a mechanism by which oscillations can be amplified parametrically. These insights should prove especially valuable in the undergraduate physics classroom, where investigations into pendulums and oscillations are commonplace.

  10. Forced responses on a radial turbine with nozzle guide vanes

    NASA Astrophysics Data System (ADS)

    Liu, Yixiong; Yang, Ce; Ma, Chaochen; Lao, DaZhong

    2014-04-01

    Radial turbines with nozzle guide vanes are widely used in various size turbochargers. However, due to the interferences with guide vanes, the blades of impellers are exposed to intense unsteady aerodynamic excitations, which cause blade vibrations and lead to high cycle failures (HCF). Moreover, the harmonic resonance in some frequency regions are unavoidable due to the wide operation conditions. Aiming to achieve a detail insight into vibration characteristics of radial flow turbine, a numerical method based on fluid structure interaction (FSI) is presented. Firstly, the unsteady aerodynamic loads are determined by computational fluid dynamics (CFD). And the fluctuating pressures are transformed from time domain to frequency domain by fast Fourier-transform (FFT). Then, the entire rotor model is adopted to analyze frequencies and mode shapes considering mistuning in finite element (FE) method. Meanwhile, harmonic analyses, applying the pressure fluctuation from CFD, are conducted to investigate the impeller vibration behavior and blade forced response in frequency domain. The prediction of the vibration dynamic stress shows acceptable agreement to the blade actual damage in consistent tendency.

  11. The effect of radial pressure force on rotating double tearing mode in compressible plasmas

    NASA Astrophysics Data System (ADS)

    Wang, Xian-Qu; Xiong, Guo-Zhen; Li, Xiao-Qing

    2016-05-01

    The role of radial pressure force in the interlocking dynamics of double tearing modes (DTMs) is investigated by force balance analysis based on the compressible magnetohydrodynamics (MHD) model. It is found that the stability of symmetric DTMs is dominated by the radial pressure force rather than the field line bending force. Owing to the compressibility of rotating plasmas, unbalanced radial forces can just result in the rotating islands drift toward each other in the radial direction but do not trigger the explosive growth of the mode in the interlocking process, which is different from that of antisymmetric DTM without flow.

  12. Second-order lower radial tangent derivatives and applications to set-valued optimization.

    PubMed

    Xu, Bihang; Peng, Zhenhua; Xu, Yihong

    2017-01-01

    We introduce the concepts of second-order radial composed tangent derivative, second-order radial tangent derivative, second-order lower radial composed tangent derivative, and second-order lower radial tangent derivative for set-valued maps by means of a radial tangent cone, second-order radial tangent set, lower radial tangent cone, and second-order lower radial tangent set, respectively. Some properties of second-order tangent derivatives are discussed, using which second-order necessary optimality conditions are established for a point pair to be a Henig efficient element of a set-valued optimization problem, and in the expressions the second-order tangent derivatives of the objective function and the constraint function are separated.

  13. Tipless Nitinol Stone Baskets: Comparison of Penetration Force, Radial Dilation Force, Opening Dynamics, and Deflection.

    PubMed

    Patel, Nishant; Akhavein, Arash; Hinck, Bryan; Jain, Rajat; Monga, Manoj

    2017-05-01

    To evaluate 5 commercially available tipless nitinol baskets (2.2F) in 4 performance factors: penetration force, radial dilation force, opening dynamics, and deflection limitation. The 2.2F Coloplast Dormia No-Tip, 1.5F Sacred Heart Medical Halo, 2.2F Cook NCircle Nitinol Tipless Stone Extractor, 1.9F Bard SkyLite Tipless Nitinol Basket, and 1.9F Boston Scientific Zero Tip Nitinol Stone Retrieval Basket were tested for penetration force (safety metric), radial dilation force (functional metric for ureteral calculi), and opening or closing dynamics. Limitation of deflection (functional metric) was tested by measuring the difference in maximal upward and downward angle of deflection of a ureteroscope with and without a basket in place. The Sacred Heart Medical Halo 1.5F basket had the highest mean force required to perforate the foil at 0.676N ± 0.117 (P < .0001). The Sacred Heart Medical Halo 1.5F basket also had the highest mean radial dilation force at 3.04 g ± 0.15 (P < .0001). The Cook NCircle Nitinol Tipless Stone Extractor 2.2F had the most linear pattern of opening, whereas the Coloplast Dormia No-Tip 2.2F and the Sacred Heart Medical Halo 1.5F exhibited exponential opening dynamics. The Cook NCircle Nitinol Tipless Stone Extractor 2.2F limited scope deflection the most with a decrease in 4° downward and 10° upward. The Sacred Heart Medical Halo 1.5F had the least influence on deflection with a decrease in 3° downward and 5° upward. The penetration force, radial dilation force, opening dynamics, and resistance to deflection varied between 5 commonly available tipless nitinol stone baskets. A small diameter 1.5F basket is capable of providing optimal performance while sacrificing linear opening. Copyright © 2017 Elsevier Inc. All rights reserved.

  14. Radial-vertical profiles of tropical cyclone derived from dropsondes

    NASA Astrophysics Data System (ADS)

    Ren, Yifang

    The scopes of this thesis research are two folds: the first one is to the construct the intensity-based composite radial-vertical profiles of tropical cyclones (TC) using GPS-based dropsonde observations and the second one is to identify the major deficiencies of Mathur vortices against the dropsonde composites of TCs. The intensity-based dropsonde composites of TCs advances our understanding of the dynamic and thermal structure of TCs of different intensity along the radial direction in and above the boundary layer where lies the devastating high wind that causes property damages and storm surges. The identification of the major deficiencies of Mathur vortices in representing the radial-vertical profiles of TC of different intensity helps to improve numerical predictions of TCs since most operational TC forecast models need to utilize bogus vortices, such as Mathur vortices, to initialize TC forecasts and simulations. We first screen all available GPS dropsonde data within and round 35 named TCs over the tropical Atlantic basin from 1996 to 2010 and pair them with TC parameters derived from the best-track data provided by the National Hurricane Center (NHC) and select 1149 dropsondes that have continuous coverage in the lower troposphere. The composite radial-vertical profiles of tangential wind speed, temperature, mixing ratio and humidity are based for each TC category ranging from "Tropical Storm" (TS) to "Hurricane Category 1" (H1) through "Hurricane Category 5" (H5). The key findings of the dropsonde composites are: (i) all TCs have the maximum tangential wind within 1 km above the ground and a distance of 1-2 times of the radius of maximum wind (RMW) at the surface; (ii) all TCs have a cold ring surrounding the warm core near the boundary layer at a distance of 1-3 times of the RMW and the cold ring structure gradually diminishes at a higher elevation where the warm core structure prevails along the radial direction; (iii) the existence of such shallow cold

  15. Estimation of the radial force using a disturbance force observer for a magnetically levitated centrifugal blood pump.

    PubMed

    Pai, C N; Shinshi, T; Shimokohbe, A

    2010-01-01

    Evaluation of the hydraulic forces in a magnetically levitated (maglev) centrifugal blood pump is important from the point of view of the magnetic bearing design. Direct measurement is difficult due to the absence of a rotor shaft, and computational fluid dynamic analysis demands considerable computational resource and time. To solve this problem, disturbance force observers were developed, using the radial controlled magnetic bearing of a centrifugal blood pump, to estimate the radial forces on the maglev impeller. In order to design the disturbance observer, the radial dynamic characteristics of a maglev impeller were evaluated under different working conditions. It was observed that the working fluid affects the additional mass and damping, while the rotational speed affects the damping and stiffness of the maglev system. Based on these results, disturbance force observers were designed and implemented. The designed disturbance force observers present a bandwidth of 45 Hz. In non-pulsatile conditions, the magnitude of the estimated radial thrust increases in proportion to the flowrate, and the rotational speed has little effect on the force direction. At 5 l/min against 100 mmHg, the estimated radial thrust is 0.95 N. In pulsatile conditions, this method was capable of estimating the pulsatile radial thrust with good response.

  16. Dependence of the beam-channel interaction force on the radial profiles of a relativistic electron beam and an ion channel in the ion-focusing regime

    NASA Astrophysics Data System (ADS)

    Kolesnikov, E. K.; Manuilov, A. S.

    2017-02-01

    We have derived the formulas for calculating the force of the interaction of a relativistic electron beam with an ion plasma channel in the case of the beam transportation during ion focusing. The dependence of the difference in radial profiles of the beam and the ion channel on this force for different amplitudes of beam deviations from the channel symmetry axis has been studied.

  17. Ball to separator contact forces in angular contact ball bearings under thrust and radial loads

    NASA Technical Reports Server (NTRS)

    Nypan, L. J.

    1978-01-01

    Experimental data are reported on ball to cage contact forces in a 110 mm bore ball bearing operating at speeds to 12,000 rpm under radial and thrust loads. Information is also reported on cage to inner race land contact force, cage to inner race land clearance, and cage to shaft speed ratios.

  18. Elastic Energy Storage and Radial Forces in the Myofilament Lattice Depend on Sarcomere Length

    PubMed Central

    Williams, C. David; Regnier, Michael; Daniel, Thomas L.

    2012-01-01

    We most often consider muscle as a motor generating force in the direction of shortening, but less often consider its roles as a spring or a brake. Here we develop a fully three-dimensional spatially explicit model of muscle to isolate the locations of forces and energies that are difficult to separate experimentally. We show the strain energy in the thick and thin filaments is less than one third the strain energy in attached cross-bridges. This result suggests the cross-bridges act as springs, storing energy within muscle in addition to generating the force which powers muscle. Comparing model estimates of energy consumed to elastic energy stored, we show that the ratio of these two properties changes with sarcomere length. The model predicts storage of a greater fraction of energy at short sarcomere lengths, suggesting a mechanism by which muscle function shifts as force production declines, from motor to spring. Additionally, we investigate the force that muscle produces in the radial or transverse direction, orthogonal to the direction of shortening. We confirm prior experimental estimates that place radial forces on the same order of magnitude as axial forces, although we find that radial forces and axial forces vary differently with changes in sarcomere length. PMID:23166482

  19. Magnetic Circuit Model of PM Motor-Generator to Predict Radial Forces

    NASA Technical Reports Server (NTRS)

    McLallin, Kerry (Technical Monitor); Kascak, Peter E.; Dever, Timothy P.; Jansen, Ralph H.

    2004-01-01

    A magnetic circuit model is developed for a PM motor for flywheel applications. A sample motor is designed and modeled. Motor configuration and selection of materials is discussed, and the choice of winding configuration is described. A magnetic circuit model is described, which includes the stator back iron, rotor yoke, permanent magnets, air gaps and the stator teeth. Iterative solution of this model yields flux linkages, back EMF, torque, power, and radial force at the rotor caused by eccentricity. Calculated radial forces are then used to determine motor negative stiffness.

  20. Axial and radial forces of cross-bridges depend on lattice spacing.

    PubMed

    Williams, C David; Regnier, Michael; Daniel, Thomas L

    2010-12-02

    Nearly all mechanochemical models of the cross-bridge treat myosin as a simple linear spring arranged parallel to the contractile filaments. These single-spring models cannot account for the radial force that muscle generates (orthogonal to the long axis of the myofilaments) or the effects of changes in filament lattice spacing. We describe a more complex myosin cross-bridge model that uses multiple springs to replicate myosin's force-generating power stroke and account for the effects of lattice spacing and radial force. The four springs which comprise this model (the 4sXB) correspond to the mechanically relevant portions of myosin's structure. As occurs in vivo, the 4sXB's state-transition kinetics and force-production dynamics vary with lattice spacing. Additionally, we describe a simpler two-spring cross-bridge (2sXB) model which produces results similar to those of the 4sXB model. Unlike the 4sXB model, the 2sXB model requires no iterative techniques, making it more computationally efficient. The rate at which both multi-spring cross-bridges bind and generate force decreases as lattice spacing grows. The axial force generated by each cross-bridge as it undergoes a power stroke increases as lattice spacing grows. The radial force that a cross-bridge produces as it undergoes a power stroke varies from expansive to compressive as lattice spacing increases. Importantly, these results mirror those for intact, contracting muscle force production.

  1. Understanding the requirements of self-expandable stents for heart valve replacement: Radial force, hoop force and equilibrium.

    PubMed

    Cabrera, María Sol; Oomens, Cees W J; Baaijens, Frank P T

    2017-04-01

    A proper interpretation of the forces developed during stent crimping and deployment is of paramount importance for a better understanding of the requirements for successful heart valve replacement. The present study combines experimental and computational methods to assess the performance of a nitinol stent for tissue-engineered heart valve implantation. To validate the stent model, the mechanical response to parallel plate compression and radial crimping was evaluated experimentally. Finite element simulations showed good agreement with the experimental findings. The computational models were further used to determine the hoop force on the stent and radial force on a rigid tool during crimping and self-expansion. In addition, stent deployment against ovine and human pulmonary arteries was simulated to determine the hoop force on the stent-artery system and the equilibrium diameter for different degrees of oversizing.

  2. SCM Forcing Data Derived from NWP Analyses

    DOE Data Explorer

    Jakob, Christian

    2008-01-15

    Forcing data, suitable for use with single column models (SCMs) and cloud resolving models (CRMs), have been derived from NWP analyses for the ARM (Atmospheric Radiation Measurement) Tropical Western Pacific (TWP) sites of Manus Island and Nauru.

  3. Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer

    NASA Technical Reports Server (NTRS)

    Mulder, Andrew; Skelley, Stephen

    2011-01-01

    Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small decrease in radial load along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the flow environment.

  4. Numerical Calculation of Total Radial Forces and Rotary Moments From the Cylinders Surface

    NASA Astrophysics Data System (ADS)

    Panichkin, A. V.; Varepo, L. G.

    2017-06-01

    The determining of the acting moments of force when the cylinder is characterized by roughness after the deformation of contacting surfaces of the rotating cylinders and the substrate while interacting with incompressible viscous liquid is still one of the main problems in printing. The numerical calculation of the radial forces and rotary moments with integral formulas for deforming surfaces was carried out with regard to the discrete grid at the grid points of the upper and lower cylinders surfaces and their deformation speeds. The paper considers the results of the numerical modeling for the quantitative assessment of rotary moments of radial forces from the cylinders surfaces, occurring during the transfer of incompressible viscous liquid on the substrate between two rotating cylinders. The definition of dynamic forces (radial and tangential force, moment of force) in the discrete form on the example of one computational cell is presented. It is noted, that the consideration of boundary deformation results in the decrease of the calculated dynamic values by 3-5 times as well as to the reducing of the ink bleeding near the boundaries of the printing surface.

  5. Experimental verification of radial magnetic levitation force on the cylindrical magnets in ferrofluid dampers

    NASA Astrophysics Data System (ADS)

    Yang, Wenming; Wang, Pengkai; Hao, Ruican; Ma, Buchuan

    2017-03-01

    Analytical and numerical calculation methods of the radial magnetic levitation force on the cylindrical magnets in cylindrical vessels filled with ferrofluid was reviewed. An experimental apparatus to measure this force was designed and tailored, which could measure the forces in a range of 0-2.0 N with an accuracy of 0.001 N. After calibrated, this apparatus was used to study the radial magnetic levitation force experimentally. The results showed that the numerical method overestimates this force, while the analytical ones underestimate it. The maximum deviation between the numerical results and the experimental ones was 18.5%, while that between the experimental results with the analytical ones attained 68.5%. The latter deviation narrowed with the lengthening of the magnets. With the aids of the experimental verification of the radial magnetic levitation force, the effect of eccentric distance of magnets on the viscous energy dissipation in ferrofluid dampers could be assessed. It was shown that ignorance of the eccentricity of magnets during the estimation could overestimate the viscous dissipation in ferrofluid dampers.

  6. Aerodynamically induced radial forces in a centrifugal gas compressor. Part 1: Experimental measurement

    SciTech Connect

    Moore, J.J.; Flathers, M.B.

    1998-04-01

    Net radial loading arising from asymmetric pressure fields in the volutes of centrifugal pumps during off-design operation is well known and has been studied extensively. In order to achieve a marked improvement in overall efficiency in centrifugal gas compressors, vaneless volute diffusers are matched to specific impellers to yield improved performance over a wide application envelope. As observed in centrifugal pumps, nonuniform pressure distributions that develop during operation above and below the design flow create static radial loads on the rotor. In order to characterize these radial forces, a novel experimental measurement and post-processing technique is employed that yields both the magnitude and direction of the load by measuring the shaft centerline locus in the tilt-pad bearings. The method is applicable to any turbomachinery operating on fluid film radial bearings equipped with proximity probes. The forces are found to be a maximum near surge and increase with higher pressures and speeds. The results are nondimensionalized, allowing the radial loading for different operating conditions to be predicted.

  7. Effect of Stent Radial Force on Stress Pattern After Deployment: A Finite Element Study

    NASA Astrophysics Data System (ADS)

    Borghi, Alessandro; Murphy, Olive; Bahmanyar, Reza; McLeod, Chris

    2014-07-01

    The present article presents a method for assessing the radial stiffness of nitinol stents. An idealized stent model was created, and its radial stiffness was calculated by means of finite element modeling. The calculations were validated against experimental measurements. The variation of radial stiffness with geometrical dimensions was calculated, and the effect of increasing radial stiffness on endovascular deployment was analyzed. Peak tensile and compressive stresses as well as stent penetration were calculated in the case of an idealized pulmonary artery model having realistic dimensions as well as stiffness. The results of stress calculations were compared with a second set of simulations, where an idealized behavior of the stent (uniform expansion to a theoretical contact diameter) was modeled. The results show how in reality nitinol stents behave in a non-ideal way, having a non-uniform expansion and exerting non-uniform pressure on the contact areas with the artery. Such non-ideality decreases though with the increase in radial stiffness. The radial force alone may be insufficient in describing the stent-artery interaction, and numerical modeling proves to be necessary for capturing such complexity.

  8. Current-induced forces: a simple derivation

    NASA Astrophysics Data System (ADS)

    Todorov, Tchavdar N.; Dundas, Daniel; Lü, Jing-Tao; Brandbyge, Mads; Hedegård, Per

    2014-11-01

    We revisit the problem of forces on atoms under current in nanoscale conductors. We derive and discuss the five principal kinds of force under steady-state conditions from a simple standpoint that—with the help of background literature—should be accessible to physics undergraduates. The discussion aims at combining methodology with an emphasis on the underlying physics through examples. We discuss and compare two forces present only under current—the non-conservative electron wind force and a Lorentz-like velocity-dependent force. It is shown that in metallic nanowires both display significant features at the wire surface, making it a candidate for the nucleation of current-driven structural transformations and failure. Finally we discuss the problem of force noise and the limitations of Ehrenfest dynamics.

  9. On the radial force balance in the quiet time magnetotail current sheet

    NASA Astrophysics Data System (ADS)

    Artemyev, A. V.; Angelopoulos, V.; Runov, A.

    2016-05-01

    Using Time History of Events and Macroscale Interactions spacecraft observations of the quite magnetotail current sheet within the r∈[9,35]RE region (r is the radial distance from Earth and RE is Earth's radius), we investigate the thermal plasma pressure distribution along the magnetotail. Taking advantage of flapping motions of an ensemble of current sheets at various distances, we estimate the current density magnitude jy (in GSM coordinates). Comparing the tension force jyBz (Bz is the magnetic field component) with the radial gradient of the plasma pressure demonstrates that this gradient is only a small fraction, ˜10-15%, of the Ampere force exerted on the cross-tail current, in the r > 15RE region. We also estimate the contribution of the electron temperature anisotropy to the pressure balance: in the r > 15RE region the corresponding force can balance only 10-15% of the observed tension force jyBz. Thus, we conclude that about 70% of the tension force is not balanced by the combination of isotropic radial pressure gradient or the electron anisotropy. We discuss mechanisms that could be responsible for balancing the magnetotail current sheet.

  10. GENERAL: Collision avoidance for a mobile robot based on radial basis function hybrid force control technique

    NASA Astrophysics Data System (ADS)

    Wen, Shu-Huan

    2009-10-01

    Collision avoidance is always difficult in the planning path for a mobile robot. In this paper, the virtual force field between a mobile robot and an obstacle is formed and regulated to maintain a desired distance by hybrid force control algorithm. Since uncertainties from robot dynamics and obstacle degrade the performance of a collision avoidance task, intelligent control is used to compensate for the uncertainties. A radial basis function (RBF) neural network is used to regulate the force field of an accurate distance between a robot and an obstacle in this paper and then simulation studies are conducted to confirm that the proposed algorithm is effective.

  11. Axial and Radial Forces of Cross-Bridges Depend on Lattice Spacing

    PubMed Central

    Williams, C. David; Regnier, Michael; Daniel, Thomas L.

    2010-01-01

    Nearly all mechanochemical models of the cross-bridge treat myosin as a simple linear spring arranged parallel to the contractile filaments. These single-spring models cannot account for the radial force that muscle generates (orthogonal to the long axis of the myofilaments) or the effects of changes in filament lattice spacing. We describe a more complex myosin cross-bridge model that uses multiple springs to replicate myosin's force-generating power stroke and account for the effects of lattice spacing and radial force. The four springs which comprise this model (the 4sXB) correspond to the mechanically relevant portions of myosin's structure. As occurs in vivo, the 4sXB's state-transition kinetics and force-production dynamics vary with lattice spacing. Additionally, we describe a simpler two-spring cross-bridge (2sXB) model which produces results similar to those of the 4sXB model. Unlike the 4sXB model, the 2sXB model requires no iterative techniques, making it more computationally efficient. The rate at which both multi-spring cross-bridges bind and generate force decreases as lattice spacing grows. The axial force generated by each cross-bridge as it undergoes a power stroke increases as lattice spacing grows. The radial force that a cross-bridge produces as it undergoes a power stroke varies from expansive to compressive as lattice spacing increases. Importantly, these results mirror those for intact, contracting muscle force production. PMID:21152002

  12. Fluctuating Pressure Environments and Hydrodynamic Radial Force Mitigation for a Two Blade Unshrouded Inducer

    NASA Technical Reports Server (NTRS)

    Mulder, Andrew; Skelley, Stephen

    2011-01-01

    Fluctuating pressure data from water flow testing of an unshrouded two blade inducer revealed a cavitation induced oscillation with the potential to induce a radial load on the turbopump shaft in addition to other more traditionally analyzed radial loads. Subsequent water flow testing of the inducer with a rotating force measurement system confirmed that the cavitation induced oscillation did impart a radial load to the inducer. After quantifying the load in a baseline configuration, two inducer shroud treatments were selected and tested to reduce the cavitation induced load. The first treatment was to increase the tip clearance, and the second was to introduce a circumferential groove near the inducer leading edge. Increasing the clearance resulted in a small load decrease along with some steady performance degradation. The groove greatly reduced the hydrodynamic load with little to no steady performance loss. The groove did however generate some new, relatively high frequency, spatially complex oscillations to the environment.

  13. Radial force on the vacuum chamber wall during thermal quench in tokamaks

    SciTech Connect

    Pustovitov, V. D.

    2015-12-15

    The radial force balance during a thermal quench in tokamaks is analyzed. As a rule, the duration τ{sub tp} of such events is much shorter than the resistive time τ{sub w} of the vacuum chamber wall. Therefore, the perturbations of the magnetic field B produced by the evolving plasma cannot penetrate the wall, which makes different the magnetic pressures on its inner and outer sides. The goal of this work is the analytical estimation of the resulting integral radial force on the wall. The plasma is considered axially symmetric; for the description of radial forces on the wall, the results of V.D. Shafranov’s classical work [J. Nucl. Energy C 5, 251 (1963)] are used. Developed for tokamaks, the standard equilibrium theory considers three interacting systems: plasma, poloidal field coils, and toroidal field coils. Here, the wall is additionally incorporated with currents driven by ∂B/∂t≠0 accompanying the fast loss of the plasma thermal energy. It is shown that they essentially affect the force redistribution, thereby leading to large loads on the wall. The estimates prove that these loads have to be accounted for in the disruptive scenarios in large tokamaks.

  14. Optimized Reduction of Unsteady Radial Forces in a Singlechannel Pump for Wastewater Treatment

    NASA Astrophysics Data System (ADS)

    Kim, Jin-Hyuk; Cho, Bo-Min; Choi, Young-Seok; Lee, Kyoung-Yong; Peck, Jong-Hyeon; Kim, Seon-Chang

    2016-11-01

    A single-channel pump for wastewater treatment was optimized to reduce unsteady radial force sources caused by impeller-volute interactions. The steady and unsteady Reynolds- averaged Navier-Stokes equations using the shear-stress transport turbulence model were discretized by finite volume approximations and solved on tetrahedral grids to analyze the flow in the single-channel pump. The sweep area of radial force during one revolution and the distance of the sweep-area center of mass from the origin were selected as the objective functions; the two design variables were related to the internal flow cross-sectional area of the volute. These objective functions were integrated into one objective function by applying the weighting factor for optimization. Latin hypercube sampling was employed to generate twelve design points within the design space. A response-surface approximation model was constructed as a surrogate model for the objectives, based on the objective function values at the generated design points. The optimized results showed considerable reduction in the unsteady radial force sources in the optimum design, relative to those of the reference design.

  15. Analytical derivation of the radial distribution function in spherical dark matter halos

    NASA Astrophysics Data System (ADS)

    Eilersen, Andreas; Hansen, Steen H.; Zhang, Xingyu

    2017-01-01

    The velocity distribution of dark matter near the Earth is important for an accurate analysis of the signals in terrestrial detectors. This distribution is typically extracted from numerical simulations. Here we address the possibility of deriving the velocity distribution function analytically. We derive a differential equation which is a function of radius and the radial component of the velocity. Under various assumptions this can be solved, and we compare the solution with the results from controlled numerical simulations. Our findings complement the previously derived tangential velocity distribution. We hereby demonstrate that the entire distribution function, below ˜0.7vesc, can be derived analytically for spherical and equilibrated dark matter structures.

  16. Analytical derivation of the radial distribution function in spherical dark matter haloes

    NASA Astrophysics Data System (ADS)

    Eilersen, Andreas; Hansen, Steen H.; Zhang, Xingyu

    2017-05-01

    The velocity distribution of dark matter near the Earth is important for an accurate analysis of the signals in terrestrial detectors. This distribution is typically extracted from numerical simulations. Here we address the possibility of deriving the velocity distribution function analytically. We derive a differential equation, which is a function of radius and the radial component of the velocity. Under various assumptions this can be solved, and we compare the solution with the results from controlled numerical simulations. Our findings complement the previously derived tangential velocity distribution. We hereby demonstrate that the entire distribution function, below ˜0.7vesc, can be derived analytically for spherical and equilibrated dark matter structures.

  17. Optimal design of high damping force engine mount featuring MR valve structure with both annular and radial flow paths

    NASA Astrophysics Data System (ADS)

    Nguyen, Q. H.; Choi, S. B.; Lee, Y. S.; Han, M. S.

    2013-11-01

    This paper focuses on the optimal design of a compact and high damping force engine mount featuring magnetorheological fluid (MRF). In the mount, a MR valve structure with both annular and radial flows is employed to generate a high damping force. First, the configuration and working principle of the proposed MR mount is introduced. The MRF flows in the mount are then analyzed and the governing equations of the MR mount are derived based on the Bingham plastic behavior of the MRF. An optimal design of the MR mount is then performed to find the optimal structure of the MR valve to generate a maximum damping force with certain design constraints. In addition, the gap size of MRF ducts is empirically chosen considering the ‘lockup’ problem of the mount at high frequency. Performance of the optimized MR mount is then evaluated based on finite element analysis and discussions on performance results of the optimized MR mount are given. The effectiveness of the proposed MR engine mount is demonstrated via computer simulation by presenting damping force and power consumption.

  18. Indirect (source-free) integration method. II. Self-force consistent radial fall

    NASA Astrophysics Data System (ADS)

    Ritter, Patxi; Aoudia, Sofiane; Spallicci, Alessandro D. A. M.; Cordier, Stéphane

    2016-12-01

    We apply our method of indirect integration, described in Part I, at fourth order, to the radial fall affected by the self-force (SF). The Mode-Sum regularization is performed in the Regge-Wheeler gauge using the equivalence with the harmonic gauge for this orbit. We consider also the motion subjected to a self-consistent and iterative correction determined by the SF through osculating stretches of geodesics. The convergence of the results confirms the validity of the integration method. This work complements and justifies the analysis and the results appeared in [Int. J. Geom. Meth. Mod. Phys. 11 (2014) 1450090].

  19. Transcriptomic analysis of the highly derived radial body plan of a sea urchin.

    PubMed

    Wygoda, Jennifer A; Yang, Yee; Byrne, Maria; Wray, Gregory A

    2014-04-01

    With their complex life cycle and highly derived body plan, echinoderms are unique among bilaterians. Although early development has been intensively studied, the molecular mechanisms underlying development of the adult echinoderm and its unusual radial body plan are largely unknown. To investigate the evolution of developmental changes in gene expression underlying radial body plan development and metamorphosis, we assembled a reference transcriptome de novo and used RNA-seq to measure gene expression profiles across larval, metamorphic, and postmetamorphic life cycle phases in the sea urchin Heliocidaris erythrogramma. Our results present a high-resolution view of gene expression dynamics during the complex transition from pre- to postmetamorphic development and suggest that distinct sets of regulatory and effector proteins are used during different life history phases. These analyses provide an important foundation for more detailed analyses of the evolution of the radial adult body of echinoderms.

  20. Three-dimensional analysis of optical forces generated by an active tractor beam using radial polarization.

    PubMed

    Carretero, Luis; Acebal, Pablo; Blaya, Salvador

    2014-02-10

    We theoretically study the three-dimensional behavior of nanoparticles in an active optical conveyor. To do this, we solved the Langevin equation when the forces are generated by a focusing system at the near field. Analytical expressions for the optical forces generated by the optical conveyor were obtained by solving the Richards and Wolf vectorial diffraction integrals in an approximated form when a mask of two annular pupils is illuminated by a radially polarized Hermite-Gauss beam. Trajectories, in both the transverse plane and the longitudinal direction, are analyzed showing that the behavior of the optical conveyor can be optimized by conveniently choosing the configuration of the mask of the two annular pupils (inner and outer radius of the two rings) in order to trap and transport all particles at the focal plane.

  1. Influence of the temperature-dependent viscosity on convective flow in the radial force field

    NASA Astrophysics Data System (ADS)

    Travnikov, Vadim; Zaussinger, Florian; Beltrame, Philippe; Egbers, Christoph

    2017-08-01

    The numerical investigation of convective flows in the radial force field caused by an oscillating electric field between spherical surfaces has been performed. A temperature difference (T1>T2 ) as well as a radial force field triggers a fluid flow similar to the Rayleigh-Bénard convection. The onset of convective flow has been studied by means of the linear stability analysis as a function of the radius ratio η =R1/R2 . The influence of the temperature-dependent viscosity has been investigated in detail. We found that a varying viscosity contrast β =ν (T2) /ν (T1) between β =1 (constant viscosity) and β =50 decreases the critical Rayleigh number by a factor of 6. Additionally, we perform a bifurcation analysis based on numerical simulations which have been calculated using a modified pseudospectral code. Numerical results have been compared with the GeoFlow experiment which is located on the International Space Station (ISS). Nonturbulent three-dimensional structures are found in the numerically predicted parameter regime. Furthermore, we observed multiple stable solutions in both experiments and numerical simulations, respectively.

  2. Inversion of radial distribution functions to pair forces by solving the Yvon-Born-Green equation iteratively.

    PubMed

    Cho, Hyung Min; Chu, Jhih-Wei

    2009-10-07

    We develop a new method to invert the target profiles of radial distribution functions (RDFs) to the pair forces between particles. The target profiles of RDFs can be obtained from all-atom molecular dynamics (MD) simulations or experiments and the inverted pair forces can be used in molecular simulations at a coarse-grained (CG) scale. Our method is based on a variational principle that determines the mean forces between CG sites after integrating out the unwanted degrees of freedom. The solution of this variational principle has been shown to correspond to the Yvon-Born-Green (YBG) equation [Noid et al., J. Phys. Chem. B 111, 4116 (2007)]. To invert RDFs, we solve the YBG equation iteratively by running a CG MD simulation at each step of iteration. A novelty of the iterative-YBG method is that during iteration, CG forces are updated according to the YBG equation without imposing any approximation as is required by other methods. As a result, only three to ten iterations are required to achieve convergence for all cases tested in this work. Furthermore, we show that not only are the target RDFs reproduced by the iterative solution; the profiles of the three-body correlation function in the YBG equation computed from all-atom and CG simulations also have a better agreement. The iterative-YBG method is applied to compute the CG forces of four molecular liquids to illustrate its efficiency and robustness: water, ethane, ethanol, and a water/methanol mixture. Using the resulting CG forces, all of the target RDFs observed in all-atom MD simulations are reproduced. We also show that the iterative-YBG method can be applied with a virial constraint to expand the representability of a CG force field. The iterative-YBG method thus provides a general and robust framework for computing CG forces from RDFs and could be systematically generalized to go beyond pairwise forces and to include higher-body interactions in a CG force field by applying the aforementioned variational

  3. Linear stability of a circular Couette flow under a radial thermoelectric body force.

    PubMed

    Yoshikawa, H N; Meyer, A; Crumeyrolle, O; Mutabazi, I

    2015-03-01

    The stability of the circular Couette flow of a dielectric fluid is analyzed by a linear perturbation theory. The fluid is confined between two concentric cylindrical electrodes of infinite length with only the inner one rotating. A temperature difference and an alternating electric tension are applied to the electrodes to produce a radial dielectrophoretic body force that can induce convection in the fluid. We examine the effects of superposition of this thermoelectric force with the centrifugal force including its thermal variation. The Earth's gravity is neglected to focus on the situations of a vanishing Grashof number such as microgravity conditions. Depending on the electric field strength and of the temperature difference, critical modes are either axisymmetric or nonaxisymmetric, occurring in either stationary or oscillatory states. An energetic analysis is performed to determine the dominant destabilizing mechanism. When the inner cylinder is hotter than the outer one, the circular Couette flow is destabilized by the centrifugal force for weak and moderate electric fields. The critical mode is steady axisymmetric, except for weak fields within a certain range of the Prandtl number and of the radius ratio of the cylinders, where the mode is oscillatory and axisymmetric. The frequency of this oscillatory mode is correlated with a Brunt-Väisälä frequency due to the stratification of both the density and the electric permittivity of the fluid. Under strong electric fields, the destabilization by the dielectrophoretic force is dominant, leading to oscillatory nonaxisymmetric critical modes with a frequency scaled by the frequency of the inner-cylinder rotation. When the outer cylinder is hotter than the inner one, the instability is again driven by the centrifugal force. The critical mode is axisymmetric and either steady under weak electric fields or oscillatory under strong electric fields. The frequency of the oscillatory mode is also correlated with the

  4. Evaluation of hydraulic radial forces on the impeller by the volute in a centrifugal rotary blood pump.

    PubMed

    Boehning, Fiete; Timms, Daniel L; Amaral, Felipe; Oliveira, Leonardo; Graefe, Roland; Hsu, Po-Lin; Schmitz-Rode, Thomas; Steinseifer, Ulrich

    2011-08-01

    In many state-of-the-art rotary blood pumps for long-term ventricular assistance, the impeller is suspended within the casing by magnetic or hydrodynamic means. For the design of such suspension systems, profound knowledge of the acting forces on the impeller is crucial. Hydrodynamic bearings running at low clearance gaps can yield increased blood damage and magnetic bearings counteracting high forces consume excessive power. Most current rotary blood pump devices with contactless bearings are centrifugal pumps that incorporate a radial diffuser volute where hydraulic forces on the impeller develop. The yielding radial forces are highly dependent on impeller design, operating point and volute design. There are three basic types of volute design--singular, circular, and double volute. In this study, the hydraulic radial forces on the impeller created by the volute in an investigational centrifugal blood pump are evaluated and discussed with regard to the choice of contactless suspension systems. Each volute type was tested experimentally in a centrifugal pump test setup at various rotational speeds and flow rates. For the pump's design point at 5 L/min and 2500 rpm, the single volute had the lowest radial force (∼0 N), the circular volute yielded the highest force (∼2 N), and the double volute possessed a force of approx. 0.5 N. Results of radial force magnitude and direction were obtained and compared with a previously performed computational fluid dynamics (CFD) study. © 2011, Copyright the Authors. Artificial Organs © 2011, International Center for Artificial Organs and Transplantation and Wiley Periodicals, Inc.

  5. Investigation on the forced response of a radial turbine under aerodynamic excitations

    NASA Astrophysics Data System (ADS)

    Ma, Chaochen; Huang, Zhi; Qi, Mingxu

    2016-04-01

    Rotor blades in a radial turbine with nozzle guide vanes typically experience harmonic aerodynamic excitations due to the rotor stator interaction. Dynamic stresses induced by the harmonic excitations can result in high cycle fatigue (HCF) of the blades. A reliable prediction method for forced response issue is essential to avoid the HCF problem. In this work, the forced response mechanisms were investigated based on a fluid structure interaction (FSI) method. Aerodynamic excitations were obtained by three-dimensional unsteady computational fluid dynamics (CFD) simulation with phase shifted periodic boundary conditions. The first two harmonic pressures were determined as the primary components of the excitation and applied to finite element (FE) model to conduct the computational structural dynamics (CSD) simulation. The computed results from the harmonic forced response analysis show good agreement with the predictions of Singh's advanced frequency evaluation (SAFE) diagram. Moreover, the mode superposition method used in FE simulation offers an efficient way to provide quantitative assessments of mode response levels and resonant strength.

  6. Adult ependymal cells are postmitotic and are derived from radial glial cells during embryogenesis.

    PubMed

    Spassky, Nathalie; Merkle, Florian T; Flames, Nuria; Tramontin, Anthony D; García-Verdugo, José Manuel; Alvarez-Buylla, Arturo

    2005-01-05

    Ependymal cells on the walls of brain ventricles play essential roles in the transport of CSF and in brain homeostasis. It has been suggested that ependymal cells also function as stem cells. However, the proliferative capacity of mature ependymal cells remains controversial, and the developmental origin of these cells is not known. Using confocal or electron microscopy (EM) of adult mice that received bromodeoxyuridine (BrdU) or [3H]thymidine for several weeks, we found no evidence that ependymal cells proliferate. In contrast, ependymal cells were labeled by BrdU administration during embryonic development. The majority of them are born between embryonic day 14 (E14) and E16. Interestingly, we found that the maturation of ependymal cells and the formation of cilia occur significantly later, during the first postnatal week. We analyzed the early postnatal ventricular zone at the EM and found a subpopulation of radial glia in various stages of transformation into ependymal cells. These cells often had deuterosomes. To directly test whether radial glia give rise to ependymal cells, we used a Cre-lox recombination strategy to genetically tag radial glia in the neonatal brain and follow their progeny. We found that some radial glia in the lateral ventricular wall transform to give rise to mature ependymal cells. This work identifies the time of birth and early stages in the maturation of ependymal cells and demonstrates that these cells are derived from radial glia. Our results indicate that ependymal cells are born in the embryonic and early postnatal brain and that they do not divide after differentiation. The postmitotic nature of ependymal cells strongly suggests that these cells do not function as neural stem cells in the adult.

  7. Experimental measurements of hydrodynamic radial forces and stiffness matrices for a centrifugal pump-impeller

    NASA Technical Reports Server (NTRS)

    Chamieh, D. S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1985-01-01

    Measurements of the steady-state hydrodynamic forces on a centrifugal pump impeller are presented as a function of position within two geometrically different volutes. These correspond to the forces experienced by the impeller at zero whirl frequency. The hydrodynamic force matrices derived from these measurements exhibit both diagonal and off-diagonal terms of substantial magnitude. These terms are of the form which would tend to excite a whirl motion in a rotordynamic analysis of the pump; this may be the cause of 'rough running' reported in many pumps. Static pressure measurements in the impeller discharge flow show that the hydrodynamic force on the impeller contains a substantial component due to the nonisotropy of the net momentum flux leaving the impeller. A similar breakdown of the contributions to the stiffness matrices reveals that the major component of these matrices results from the nonisotropy of the momentum flux.

  8. Experimental measurements of hydrodynamic radial forces and stiffness matrices for a centrifugal pump-impeller

    NASA Technical Reports Server (NTRS)

    Chamieh, D. S.; Acosta, A. J.; Brennen, C. E.; Caughey, T. K.

    1985-01-01

    Measurements of the steady-state hydrodynamic forces on a centrifugal pump impeller are presented as a function of position within two geometrically different volutes. These correspond to the forces experienced by the impeller at zero whirl frequency. The hydrodynamic force matrices derived from these measurements exhibit both diagonal and off-diagonal terms of substantial magnitude. These terms are of the form which would tend to excite a whirl motion in a rotordynamic analysis of the pump; this may be the cause of 'rough running' reported in many pumps. Static pressure measurements in the impeller discharge flow show that the hydrodynamic force on the impeller contains a substantial component due to the nonisotropy of the net momentum flux leaving the impeller. A similar breakdown of the contributions to the stiffness matrices reveals that the major component of these matrices results from the nonisotropy of the momentum flux.

  9. 'Generalizability' of a radial-aortic transfer function for the derivation of central aortic waveform parameters.

    PubMed

    Hope, Sarah A; Meredith, Ian T; Tay, David; Cameron, James D

    2007-09-01

    Arterial transfer functions (TFs) describe the relationship between the pressure waveform at different arterial sites. Generalized TFs are used to reconstruct central aortic waveforms from non-invasively obtained peripheral waveforms and have been promoted as potentially clinically useful. A limitation is the paucity of information on their 'generalizability' with no information existing on the number of subjects required to construct a satisfactory TF, nor is adequate prospective validation available. We therefore investigated the uniformity of radial-aortic TFs and prospectively estimated the capacity of a generalized TF to reconstruct individual central blood pressure parameters. Ninety-three subjects (64 male) were studied by simultaneous radial applanation and high-fidelity (Millar Mikro-tip catheter) direct measurement of central aortic BP during elective coronary procedures. Subjects were prospectively randomized to either a derivation or validation group. Increasing numbers of individual TFs from the derivation group were averaged to form a generalized TF. There was minimal change with greater than 20 TFs averaged. In the validation group, the error in most reconstructed parameters related to the absolute value of the directly measured parameter [systolic blood pressure (SBP) and pulse pressure, P<0.05; systolic pressure-time interval, subendocardial viability index, augmentation index, and times to the inflection point, peak and end systole, all P<0.01]. Aorto-radial delay was related to error in reconstructed central aortic SBP and pulse pressure (negatively) and time to peak systole (positively) (all P<0.001). Reconstruction of augmentation index was poor. Inclusion of more than 20 individual TFs in the construction of a generalized TF does not improve 'generalizability'. There appear to be systematic errors in derived central pressure waveforms and derived aortic augmentation index is inaccurate compared to the directly measured value.

  10. RADIAL DISTRIBUTION OF STARS, GAS, AND DUST IN SINGS GALAXIES. II. DERIVED DUST PROPERTIES

    SciTech Connect

    Munoz-Mateos, J. C.; Gil de Paz, A.; Zamorano, J. E-mail: agpaz@astrax.fis.ucm.es

    2009-08-20

    We present a detailed analysis of the radial distribution of dust properties in the SINGS sample, performed on a set of ultraviolet (UV), infrared (IR), and H I surface brightness profiles, combined with published molecular gas profiles and metallicity gradients. The internal extinction, derived from the total-IR (TIR)-to-far-UV (FUV) luminosity ratio, decreases with radius, and is larger in Sb-Sbc galaxies. The TIR-to-FUV ratio correlates with the UV spectral slope {beta}, following a sequence shifted to redder UV colors with respect to that of starbursts. The star formation history (SFH) is identified as the main driver of this departure. Both L {sub TIR}/L {sub FUV} and {beta} correlate well with metallicity, especially in moderately face-on galaxies. The relation shifts to redder colors with increased scatter in more edge-on objects. By applying physical dust models to our radial spectral energy distributions, we have derived radial profiles of the total dust mass surface density, the fraction of the total dust mass contributed by polycyclic aromatic hydrocarbons (PAHs), and the intensity of the radiation field heating the grains. The dust profiles are exponential, their radial scale length being constant from Sb to Sd galaxies (only {approx}10% larger than the stellar scale length). Many S0/a-Sab galaxies have central depressions in their dust radial distributions. The PAH abundance increases with metallicity for 12 + log(O/H) < 9, and at larger metallicities the trend flattens and even reverses, with the SFH being a plausible underlying driver for this behavior. The dust-to-gas ratio is also well correlated with metallicity and therefore decreases with galactocentric radius. Although most of the total emitted IR power (especially in the outer regions of disks) is contributed by dust grains heated by diffuse starlight with a similar intensity as the local Milky Way radiation field, a small amount of the dust mass ({approx}1%) is required to be exposed to very

  11. Optimal radial force and size for palliation in gastroesophageal adenocarcinoma: a comparative analysis of current stent technology.

    PubMed

    Mbah, Nsehniitooh; Philips, Prejesh; Voor, Michael J; Martin, Robert C G

    2017-04-25

    The optimal use of esophageal stents for malignant and benign esophageal strictures continues to be plagued with variability in pain tolerance, migration rates, and reflux-related symptoms. The aim of this study was to evaluate the differences in radial force exhibited by a variety of esophageal stents with respect to the patient's esophageal stricture. Radial force testing was performed on eight stents manufactured by four different companies using a hydraulic press and a 5000 N force gage. Radial force was measured using three different tests: transverse compression, circumferential compression, and a three-point bending test. Esophageal stricture composition and diameters were measured to assess maximum diameter, length, and proximal esophageal diameter among 15 patients prior to stenting. There was a statistically significant difference in mean radial force for transverse compression tests at the middle (range 4.25-0.66 newtons/millimeter N/mm) and at the flange (range 3.32-0.48 N/mm). There were also statistical differences in mean radial force for circumferential test (ranged from 1.19 to 10.50 N/mm, p < 0.001) and the three-point bending test (range 0.08-0.28 N/mm, p < 0.001). In an evaluation of esophageal stricture diameters and lengths, the smallest median diameter of the stricture was 10 mm (range 5-16 mm) and the median proximal diameter normal esophagus was 25 mm (range 22-33 mm), which is currently outside of the range of stent diameters. Tested stents demonstrated significant differences in radial force, which provides further clarification of stent pain and intolerance in certain patients, with either benign or malignant disease. Similarly, current stent diameters do not successfully exclude the proximal esophagus, which can lead to obstructive-type symptoms. Awareness of radial force, esophageal stricture composition, and proximal esophageal diameter must be known and understood for optimal stent tolerance.

  12. Method for Cleanly and Precisely Breaking Off a Rock Core Using a Radial Compressive Force

    NASA Technical Reports Server (NTRS)

    Richardson, Megan; Lin, Justin

    2011-01-01

    The Mars Sample Return mission has the goal to drill, break off, and retain rock core samples. After some results gained from rock core mechanics testing, the realization that scoring teeth would cleanly break off the core after only a few millimeters of penetration, and noting that rocks are weak in tension, the idea was developed to use symmetric wedging teeth in compression to weaken and then break the core at the contact plane. This concept was developed as a response to the break-off and retention requirements. The wedges wrap around the estimated average diameter of the core to get as many contact locations as possible, and are then pushed inward, radially, through the core towards one another. This starts a crack and begins to apply opposing forces inside the core to propagate the crack across the plane of contact. The advantage is in the simplicity. Only two teeth are needed to break five varieties of Mars-like rock cores with limited penetration and reasonable forces. Its major advantage is that it does not require any length of rock to be attached to the parent in order to break the core at the desired location. Test data shows that some rocks break off on their own into segments or break off into discs. This idea would grab and retain a disc, push some discs upward and others out, or grab a segment, break it at the contact plane, and retain the portion inside of the device. It also does this with few moving parts in a simple, space-efficient design. This discovery could be implemented into a coring drill bit to precisely break off and retain any size rock core.

  13. Source-free integration method for black hole perturbations and self-force computation: Radial fall

    NASA Astrophysics Data System (ADS)

    Aoudia, Sofiane; Spallicci, Alessandro D. A. M.

    2011-03-01

    Perturbations of Schwarzschild-Droste black holes in the Regge-Wheeler gauge benefit from the availability of a wave equation and from the gauge invariance of the wave function, but lack smoothness. Nevertheless, the even perturbations belong to the C0 continuity class, if the wave function and its derivatives satisfy specific conditions on the discontinuities, known as jump conditions, at the particle position. These conditions suggest a new way for dealing with finite element integration in the time domain. The forward time value in the upper node of the (t,r*) grid cell is obtained by the linear combination of the three preceding node values and of analytic expressions based on the jump conditions. The numerical integration does not deal directly with the source term, the associated singularities and the potential. This amounts to an indirect integration of the wave equation. The known wave forms at infinity are recovered and the wave function at the particle position is shown. In this series of papers, the radial trajectory is dealt with first, being this method of integration applicable to generic orbits of EMRI (Extreme Mass Ratio Inspiral).

  14. Effect of non-invasive calibration of radial waveforms on error in transfer-function-derived central aortic waveform characteristics.

    PubMed

    Hope, Sarah A; Meredith, Ian T; Cameron, James D

    2004-08-01

    Transfer function techniques are increasingly used for non-invasive estimation of central aortic waveform characteristics. Non-invasive radial waveforms must be calibrated for this purpose. Most validation studies have used invasive pressures for calibration, with little data on the impact of non-invasive calibration on transfer-function-derived aortic waveform characteristics. In the present study, simultaneous invasive central aortic (Millar Mikro-tip catheter transducer) and non-invasive radial (Millar Mikro-tip tonometer) pressure waveforms and non-invasive brachial pressures (Dinamap) were measured in 42 subjects. In this cohort, radial waveforms were calibrated to both invasive and non-invasive mean and diastolic pressures. From each of these, central waveforms were reconstructed using a generalized transfer function obtained by us from a previous cohort [Hope, Tay, Meredith and Cameron (2002) Am. J. Physiol. Heart Circ. Physiol. 283, H1150-H1156]. Waveforms were analysed for parameters of potential clinical interest. For calibrated radial and reconstructed central waveforms, different methods of calibration were associated with differences in pressure (P<0.001), but not time parameters or augmentation index. Whereas invasive calibration resulted in little error in transfer function estimation of central systolic pressure (difference -1+/-8 mmHg; P=not significant), non-invasive calibration resulted in significant underestimation (7+/-12 mmHg; P<0.001). Errors in estimated aortic parameters differed with non-invasively calibrated untransformed radial and transfer-function-derived aortic waveforms (all P<0.01), with smaller absolute errors with untransformed radial waveforms for most pressure parameters [systolic pressure, 5+/-16 and 7+/-12 mmHg; pulse pressure, 0+/-16 and 4+/-12 mmHg (radial and derived aortic respectively)]. When only non-invasive pressures are accessible, analysis of untransformed radial waveforms apparently produces smaller errors in the

  15. Nonlinear mechanics of a ring structure subjected to multi-pairs of evenly distributed equal radial forces

    NASA Astrophysics Data System (ADS)

    Chen, Q.; Sun, F.; Li, Z. Y.; Taxis, L.; Pugno, N.

    2017-05-01

    Combining the elastica theory, finite element (FE) analysis, and a geometrical topological experiment, we studied the mechanical behavior of a ring subjected to multi-pairs of evenly distributed equal radial forces by looking at its seven distinct states. The results showed that the theoretical predictions of the ring deformation and strain energy matched the FE results very well, and that the ring deformations were comparable to the topological experiment. Moreover, no matter whether the ring was compressed or tensioned by N-pairs of forces, the ring always tended to be regular polygons with 2N sides as the force increased, and a proper compressive force deformed the ring into exquisite flower-like patterns. The present study solves a basic mechanical problem of a ring subjected to lateral forces, which can be useful for studying the relevant mechanical behavior of ring structures from the nano- to the macro-scale.

  16. Research on the effect of wear-ring clearances to the axial and radial force of a centrifugal pump

    NASA Astrophysics Data System (ADS)

    Zhao, W. G.; Y He, M.; Qi, C. X.; Li, Y. B.

    2013-12-01

    Varying of the wear-ring clearance not only has a distinct effect on the volumetric loss of the centrifugal pump, but also on the performance of the centrifugal pump including the axial and radial forces. Comparing with the experimental studies, numerical simulation methods have some special advantages, such as the low cost, fast and high efficiency, and convenient to get the detailed structure of the internal flow characteristics, so it has been widely used in the fluid machinery study in recent years. In order to study the effect of wear-ring clearance on the force performance of the centrifugal pump, based on the Reynolds Time-Averaged N-S equations and RNG k-ε turbulence model, a centrifugal pump with three variable styles of the wear-rings was simulated: Only the clearance of the front wear-ring was changed, only the clearance of the back wear-ring was changed and both were changed. Comparing with the experiment, numerical results show a good agreement. In the three changing styles of the clearance, the variable of the clearance of front wear-ring has the most influence on the axial force of the centrifugal pump, while has tiny effect on the radial force for all the conditions.

  17. Stromal-derived factor 1 signalling regulates radial and tangential migration in the developing cerebral cortex.

    PubMed

    Liapi, Anastasia; Pritchett, James; Jones, Owen; Fujii, Nobutaka; Parnavelas, John G; Nadarajah, Bagirathy

    2008-01-01

    Stromal-derived factor 1 (SDF-1), a known chemoattractant, and its receptor CXCR4 are widely expressed in the developing and adult cerebral cortex. Recent studies have highlighted potential roles for SDF-1 during early cortical development. In view of the current findings, our histological analysis has revealed a distinct pattern of SDF-1 expression in the developing cerebral cortex at a time when cell proliferation and migration are at peak. To determine the role of chemokine signalling during early cortical development, embryonic rat brain slices were exposed to a medium containing secreted SDF-1 to perturb the endogenous levels of chemokine. Alternatively, brain slices were treated with 40 muM of T140 or AMD3100, known antagonists of CXCR4. Using these experimental approaches, we demonstrate that chemokine signalling is imperative for the maintenance of the early cortical plate. In addition, we provide evidence that both neurogenesis and radial migration are concomitantly regulated by this signalling system. Conversely, interneurons, although not dependent on SDF-1 signalling to transgress the telencephalic boundary, require the chemokine to maintain their tangential migration. Collectively, our results demonstrate that SDF-1 with its distinct pattern of expression is essential and uniquely positioned to regulate key developmental events that underlie the formation of the cerebral cortex.

  18. Electromagnetic Radial Forces in a Hybrid Eight-Stator-Pole, Six-Rotor-Pole Bearingless Switched-Reluctance Motor

    NASA Technical Reports Server (NTRS)

    Morrison, Carlos R.; Siebert, Mark W.; Ho, Eric J.

    2007-01-01

    Analysis and experimental measurement of the electromagnet force loads on the hybrid rotor in a novel bearingless switched-reluctance motor (BSRM) have been performed. A BSRM has the combined characteristics of a switched-reluctance motor and a magnetic bearing. The BSRM has an eight-pole stator and a six-pole hybrid rotor, which is composed of circular and scalloped lamination segments. The hybrid rotor is levitated using only one set of stator poles. A second set of stator poles imparts torque to the scalloped portion of the rotor, which is driven in a traditional switched reluctance manner by a processor. Analysis was done for nonrotating rotor poles that were oriented to achieve maximum and minimum radial force loads on the rotor. The objective is to assess whether simple one-dimensional magnetic circuit analysis is sufficient for preliminary evaluation of this machine, which may exhibit strong three-dimensional electromagnetic field behavior. Two magnetic circuit geometries, approximating the complex topology of the magnetic fields in and around the hybrid rotor, were employed in formulating the electromagnetic radial force equations. Reasonable agreement between the experimental results and the theoretical predictions was obtained with typical magnetic bearing derating factors applied to the predictions.

  19. Comparison of Response Surface Construction Methods for Derivative Estimation Using Moving Least Squares, Kriging and Radial Basis Functions

    NASA Technical Reports Server (NTRS)

    Krishnamurthy, Thiagarajan

    2005-01-01

    Response construction methods using Moving Least Squares (MLS), Kriging and Radial Basis Functions (RBF) are compared with the Global Least Squares (GLS) method in three numerical examples for derivative generation capability. Also, a new Interpolating Moving Least Squares (IMLS) method adopted from the meshless method is presented. It is found that the response surface construction methods using the Kriging and RBF interpolation yields more accurate results compared with MLS and GLS methods. Several computational aspects of the response surface construction methods also discussed.

  20. Numerical derivation of forced nutation terms for a rigid earth

    NASA Technical Reports Server (NTRS)

    Schastok, J.; Soffel, M.; Ruder, H.

    1990-01-01

    The results of a numerical integration of the Euler equations for a rigid earth model covering a time span of 250 years are compared with Kinoshita's (1977) theory for the forced nutations and with a new nutation series by Kinoshita and Souchay. Numerical corrections to some of the analytically derived nutation terms are presented.

  1. Displacement coefficients along the inner boundaries of radially cracked ring segments subject to forces and couples

    NASA Technical Reports Server (NTRS)

    Gross, B.

    1977-01-01

    Displacement results of plane boundary collocation analysis are given for various locations on the inner boundaries of radially cracked ring segments (C-shaped specimens) subject to two complementary types of loading. Results are presented for ratios of outer to inner radius R sub o/R sub i in the range of 1.1 to 2.5, and ratios a/W in the range 0.1 to 0.8 where a is the crack length for a specimen of wall thickness W. By combination of these results the resultant displacement coefficient delta or the corresponding influence coefficient, can be obtained for any practical load line location of a pin loaded specimen.

  2. Force-Time Curve Comparison Between Weightlifting Derivatives.

    PubMed

    Suchomel, Timothy J; Sole, Christopher J

    2016-08-24

    The force production characteristics of three weightlifting derivatives were examined by comparing the force-time curves of each exercise. Sixteen resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform at several relative loads. Relative peak force (PFRel), relative impulse (IMPRel), peak rate of force development (PRFD), and time normalized force-time curves of each exercise were compared. The JS produced greater PFRel compared to the HPC (p < 0.001, d = 1.38) and HHP (p < 0.001, d = 1.14), while no difference existed between the HPC and HHP (p = 0.338, d = 0.26). Similarly, the JS produced greater IMPRel compared to the HPC (p < 0.001, d = 0.52) and HHP (p = 0.019, d = 0.36). The HHP also produced greater IMPRel compared to the HPC (p = 0.040, d = 0.18). Finally, the JS produced greater PRFD compared to the HPC (p < 0.001, d = 0.73) and HHP (p = 0.001, d = 0.47), while no difference existed between the HPC and HHP (p = 0.192, d = 0.22). The HPC, JS, and HHP force-time profiles were similar during the first 75-80% of the movement; however, the JS produced markedly different force-time characteristics in the final 20-25% of the movement. The JS produced superior force production characteristics, namely PFRel, IMPRel, and PRFD, as well as a unique force-time profile, compared to the HPC and HHP across several loads.

  3. Numerical analysis of the radial force produced by the Medtronic-CoreValve and Edwards-SAPIEN after transcatheter aortic valve implantation (TAVI).

    PubMed

    Tzamtzis, S; Viquerat, J; Yap, J; Mullen, M J; Burriesci, G

    2013-01-01

    A better understanding of the mechanisms producing the radial force in transcatheter heart valves is essential in order to reduce the reported cases of migration and atrio-ventricular block and improve the effectiveness of the treatment. This paper presents a numerical study of the different mechanisms responsible for the radial force exerted on the aortic annulus by self-expanding and balloon-expandable prostheses. The behavior of the Medtronic CoreValve (self-expanding) and the Edwards SAPIEN (balloon-expandable) devices, both of size 26, has been simulated and compared. The results indicate that, for both prostheses, the radial force may vary considerably within the recommended functional range for the valve implantation and is substantially higher at the smallest annular sizes. In particular, in the case of the self-expanding valve the radial force is essentially dependent on the diameter of the left ventricular outflow tract, while for the balloon-expandable valve the radial force produced is influenced by both the geometry and stiffness of the host tissue. The outcomes of this study provide a better insight into the phenomenon and useful information that could support the development of improved solutions. Copyright © 2012 IPEM. Published by Elsevier Ltd. All rights reserved.

  4. Assimilation of HF Radar-Derived Radials and Total Currents in the Monterey Bay Area

    DTIC Science & Technology

    2009-01-01

    km, while the range for the 25.4-MHz systen was about 40km. Vector current estimates require overlapping radial observations from two or more HF...34filtered" indicates that both model-simulated and observed currents were low pass filtered (33-h half- power point) prior tc calculation of the...and observed currents were low pass filtered (33-h half- power point) prior to calculation of the complex correlations. -60 -40 Angle (degrees

  5. Collision of viscoelastic bodies: Rigorous derivation of dissipative force.

    PubMed

    Goldobin, Denis S; Susloparov, Eugeniy A; Pimenova, Anastasiya V; Brilliantov, Nikolai V

    2015-06-01

    We report a new theory of dissipative forces acting between colliding viscoelastic bodies. The impact velocity is assumed not to be large to neglect plastic deformations in the material and propagation of sound waves. We consider the general case of bodies of an arbitrary convex shape and of different materials. We develop a mathematically rigorous perturbation scheme to solve the continuum mechanics equations that deal with both displacement and displacement rate fields and accounts for the dissipation in the bulk of the material. The perturbative solution of these equations allows to go beyond the previously used quasi-static approximation and obtain the dissipative force. The derived force does not suffer from the inconsistencies of the quasi-static approximation, like the violation of the third Newton's law for the case of different materials, and depends on particle deformation and deformation rate.

  6. Analysis of radial and longitudinal force of plasma wakefield generated by a chirped pulse laser

    SciTech Connect

    Ghasemi, Leila; Afhami, Saeedeh; Eslami, Esmaeil

    2015-08-15

    In present paper, the chirp effect of an electromagnetic pulse via an analytical model of wakefield generation is studied. Different types of chirps are employed in this study. Our results show that by the use of nonlinear chirped pulse the longitudinal wakefield and focusing force is stronger than that of linear chirped pulse. It is indicated that quadratic nonlinear chirped pulses are globally much efficient than periodic nonlinear chirped pulses. Our calculations also predict that in nonlinear chirped pulse case, the overlap of focusing and accelerating regions is broader than that achieved in linear chirped pulse.

  7. Brachial blood pressure-independent relations between radial late systolic shoulder-derived aortic pressures and target organ changes.

    PubMed

    Norton, Gavin R; Majane, Olebogeng H I; Maseko, Muzi J; Libhaber, Carlos; Redelinghuys, Michelle; Kruger, Deirdre; Veller, Martin; Sareli, Pinhas; Woodiwiss, Angela J

    2012-04-01

    Central aortic blood pressure (BP; BPc) predicts outcomes beyond brachial BP. In this regard, the application of a generalized transfer function (GTF) to radial pulse waves for the derivation of BPc is an easy and reproducible measurement technique. However, the use of the GTF may not be appropriate in all circumstances. Although the peak of the second shoulder of the radial waveform (P2) is closely associated with BPc, and, hence, BPc may be assessed without the need for a GTF, whether P2-derived BPc is associated with adverse cardiovascular changes independent of brachial BP is uncertain. Thus, P2- and GTF-derived aortic BPs were assessed using applanation tonometry and SphygmoCor software. Left ventricular mass was indexed for height(1.7) (n=678) and carotid intima-media thickness (IMT; n=462) was determined using echocardiography and vascular ultrasound. With adjustments for nurse-derived brachial pulse pressure (PP), P2-derived central PP was independently associated with left ventricular mass indexed for height(1.7) (partial r=0.18; P<0.0001) and IMT (partial r=0.40; P<0.0001). These relations were similar to nurse-derived brachial PP-independent relations between GTF-derived central PP and target organ changes (left ventricular mass indexed for height(1.7): partial r=0.17, P<0.0001; IMT: partial r=0.37, P<0.0001). In contrast, with adjustments for central PP, nurse-derived brachial PP-target organ relations were eliminated (partial r=-0.21 to 0.05). Twenty-four-hour, day, and night PP-target organ relations did not survive adjustments for nurse-derived brachial BP. In conclusion, central PP derived from P2, which does not require a GTF, is associated with cardiovascular target organ changes independent of brachial BP. Thus, when assessing adverse cardiovascular effects of aortic BP independent of brachial BP, P2-derived measures may complement GTF-derived measures of aortic BP.

  8. Accurate Satellite-Derived Estimates of Tropospheric Ozone Radiative Forcing

    NASA Technical Reports Server (NTRS)

    Joiner, Joanna; Schoeberl, Mark R.; Vasilkov, Alexander P.; Oreopoulos, Lazaros; Platnick, Steven; Livesey, Nathaniel J.; Levelt, Pieternel F.

    2008-01-01

    Estimates of the radiative forcing due to anthropogenically-produced tropospheric O3 are derived primarily from models. Here, we use tropospheric ozone and cloud data from several instruments in the A-train constellation of satellites as well as information from the GEOS-5 Data Assimilation System to accurately estimate the instantaneous radiative forcing from tropospheric O3 for January and July 2005. We improve upon previous estimates of tropospheric ozone mixing ratios from a residual approach using the NASA Earth Observing System (EOS) Aura Ozone Monitoring Instrument (OMI) and Microwave Limb Sounder (MLS) by incorporating cloud pressure information from OMI. Since we cannot distinguish between natural and anthropogenic sources with the satellite data, our estimates reflect the total forcing due to tropospheric O3. We focus specifically on the magnitude and spatial structure of the cloud effect on both the shortand long-wave radiative forcing. The estimates presented here can be used to validate present day O3 radiative forcing produced by models.

  9. Evaluation of the radial deformability of poly(dG)-poly(dC) DNA and G4-DNA using vibrating scanning polarization force microscopy.

    PubMed

    Wang, Huabin; Lin, Jiwei; Wang, Chunmei; Zhang, Xuehua; An, Hongjie; Zhou, Xingfei; Sun, Jielin; Hu, Jun

    2010-05-18

    Poly(dG)-poly(dC) DNA and G4-DNA are two types of synthetic molecules that are regarded as promising candidates for molecular nanodevices. In this work, vibrating scanning polarization force microscopy (VSPFM) was employed to study the radial deformability of these two molecules coadsorbed on a Ni(2+)-modified mica surface. The values of the radial compressive elastic modulus of these two types of molecules were found to be similar (approximately 5-10 MPa) when the external loading force was between approximately 0.04 and approximately 0.12 nN. However, G4-DNA molecules possessed higher stiffness than poly(dG)-poly(dC) DNA (approximately 20-40 vs approximately 10-20 MPa) when the loading force was larger than approximately 0.12 nN. The results will aid us in understanding these molecule's mechanical performances.

  10. Radial derivatives of the mouse ventral pallium traced with Dbx1-LacZ reporters.

    PubMed

    Puelles, Luis; Medina, Loreta; Borello, Ugo; Legaz, Isabel; Teissier, Anne; Pierani, Alessandra; Rubenstein, John L R

    2016-09-01

    The progeny of Dbx1-expressing progenitors was studied in the developing mouse pallium, using two transgenic mouse lines: (1) Dbx1(nlslacZ) mice, in which the gene of the β-galactosidase reporter (LacZ) is inserted directly under the control of the Dbx1 promoter, allowing short-term lineage tracing of Dbx1-derived cells; and (2) Dbx1(CRE) mice crossed with a Cre-dependent reporter strain (ROSA26(loxP-stop-loxP-LacZ)), in which the Dbx1-derived cells result permanently labeled (Bielle et al., 2005). We thus examined in detail the derivatives of the postulated longitudinal ventral pallium (VPall) sector, which has been defined among other features by its selective ventricular zone expression of Dbx1 (the recent ascription by Puelles, 2014 of the whole olfactory cortex primordium to the VPall was tested). Earlier notions about a gradiental caudorostral reduction of Dbx1 signal were corroborated, so that virtually no signal was found at the olfactory bulb and the anterior olfactory area. The piriform cortex was increasingly labeled caudalwards. The only endopiriform grisea labeled were the ventral endopiriform nucleus and the bed nucleus of the external capsule. Anterior and basolateral parts of the whole pallial amygdala also were densely marked, in contrast to the negative posterior parts of these pallial amygdalar nuclei (leaving apart medial amygdalar parts ascribed to subpallial or extratelencephalic sources of Dbx1-derived GABAergic and non-GABAergic neurons). Alternative tentative interpretations are discussed to explain the partial labeling obtained of both olfactory and amygdaloid structures. This includes the hypothesis of an as yet undefined part of the pallium, potentially responsible for the posterior amygdala, or the hypothesis that the VPall may not be wholly characterized by Dbx1 expression (this gene not being necessary for VPall molecular distinctness and histogenetic potency), which would leave a dorsal Dbx1-negative VPall subdomain of variable size

  11. Authentication of Radial Versus Femoral Arterial Pressure Waveform-Derived Cardiac Output With Transesophageal Echocardiography-Derived Cardiac Output Measurements in Patients Undergoing On-Pump Coronary Bypass Surgery.

    PubMed

    Maddali, Madan Mohan; Waje, Niranjan Dilip; Sathiya, Panchatcharam Murthi

    2017-08-01

    The aim of this study was to ascertain if arterial waveform-derived cardiac output measurements from radial and femoral cannulation sites were reliable as compared with transesophageal echocardiography (TEE)-derived cardiac output (CO) values, and which of the CO measurements derived from radial and the femoral arterial pressure waveforms closely tracked simultaneously measured TEE-derived CO values. This study also aimed to ascertain if cardiopulmonary bypass (CPB) would impact the accuracy of arterial pressure-derived CO values from either of the 2 sites. A prospective observational study. Tertiary care cardiac center. Cardiac surgical patients undergoing on-pump primary coronary artery bypass surgery. Waveform-derived CO monitoring through radial and femoral artery cannulation using a FloTrac/Vigileo system. Twenty-seven consecutive cardiac surgical patients undergoing on-pump primary coronary artery bypass surgery were included in the study. Cardiac output was measured sequentially by the arterial pressure waveform analysis method from radial and femoral arterial sites and compared with simultaneously measured TEE-derived CO. Cardiac output data were obtained in triplicate at 6 predefined time intervals: before and after sternotomy, 5, 15, and 30 minutes after separation from CPB and prior to shifting the patient out of the operating room. The overall bias of the study was 0.11 and 0.27, the percentage error was 19.31 and 18.45, respectively, for radial and femoral arterial waveform-derived CO values as compared with TEE-derived CO measurements. The overall precision as compared with the TEE-derived CO values was 16.94 and 15.95 for the radial and femoral cannulation sites, respectively. The bias calculated by the Bland-Altman method suggested that CO measurements from the radial arterial site were in closer agreement with TEE-derived CO values at all time periods, and the relation was not affected by CPB. However, percentage error and precision calculations

  12. Astrometric light-travel time signature of sources in nonlinear motion. I. Derivation of the effect and radial motion

    NASA Astrophysics Data System (ADS)

    Anglada-Escudé, G.; Torra, J.

    2006-04-01

    Context: .Very precise planned space astrometric missions and recent improvements in imaging capabilities require a detailed review of the assumptions of classical astrometric modeling.Aims.We show that Light-Travel Time must be taken into account in modeling the kinematics of astronomical objects in nonlinear motion, even at stellar distances.Methods.A closed expression to include Light-Travel Time in the current astrometric models with nonlinear motion is provided. Using a perturbative approach the expression of the Light-Travel Time signature is derived. We propose a practical form of the astrometric modelling to be applied in astrometric data reduction of sources at stellar distances(d>1 pc).Results.We show that the Light-Travel Time signature is relevant at μ as accuracy (or even at mas) depending on the time span of the astrometric measurements. We explain how information on the radial motion of a source can be obtained. Some estimates are provided for known nearby binary systemsConclusions.Given the obtained results, it is clear that this effect must be taken into account in interpreting precise astrometric measurements. The effect is particularly relevant in measurements performed by the planned astrometric space missions (GAIA, SIM, JASMINE, TPF/DARWIN). An objective criterion is provided to quickly evaluate whether the Light-Travel Time modeling is required for a given source or system.

  13. A new model of Earth's radial conductivity structure derived from over 10 yr of satellite and observatory magnetic data

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Kuvshinov, Alexey; Khan, Amir; Olsen, Nils

    2015-12-01

    We present a new model of the radial (1-D) conductivity structure of Earth's mantle. This model is derived from more than 10 yr of magnetic measurements from the satellites Ørsted, CHAMP, SAC-C and the Swarm trio as well as the global network of geomagnetic observatories. After removal of core and crustal field as predicted by a recent field model, we fit the magnetic data with spherical harmonic coefficients describing ring current activity and associated induction effects and estimate global C-responses at periods between 1.5 and 150 d. The C-responses are corrected for 3-D effects due to induction in the oceans and inverted for a 1-D model of mantle conductivity using both probabilistic and deterministic methods. Very similar results are obtained, consisting of a highly resistive upper mantle, an increase in conductivity in and beneath the transition zone and a conductive lower mantle. Analysis of the Hessian of the cost function reveals that the data are most sensitive to structures at depths between 800 and 1200 km, in agreement with the results obtained from the probabilistic approach. Preliminary interpretation of the inverted conductivity structure based on laboratory-based conductivity profiles shows that the recovered structure in the lower mantle either requires higher temperatures or the presence of material of high conductivity related to ponding of carbonate melts below the transition zone.

  14. A new model of Earth's radial conductivity structure derived from over 10 years of satellite and observatory magnetic data

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Kuvshinov, Alexey; Olsen, Nils; Khan, Amir

    2015-04-01

    We present a new model of the radial (1-D) conductivity structure of Earth's mantle. This model was derived from more than ten years of magnetic measurements taken by the satellites Ørsted, CHAMP, SAC-C and the Swarm trio as well as the global network of geomagnetic observatories. After removal of core and crustal field as predicted by a recent field model we fit the data with spherical harmonic coefficients describing ring current activity and associated induction effects, and estimate global C-responses at periods between 1.5 days and 150 days. An iterative approach is used to correct the estimated C-responses for 3-D effects arising from induction in a heterogeneous surface shell that takes into account the distribution of oceans and continents. We invert the corrected C-responses for a 1-D model of mantle conductivity using both probabilistic and deterministic methods. The different methods yield very similar results, consisting of a highly resistive upper mantle, a conductive lower mantle, and an increase in conductivity in and beneath the transition zone. Analysis of the Hessian of the cost function reveals that the data are most sensitive to structures at depths between 700 km and 1200 km, in agreement with the results obtained from the probabilistic approach. The recovered models feature a marked kink in this well-resolved depth range.

  15. Pluripotent stem cell-derived radial glia-like cells as stable intermediate for efficient generation of human oligodendrocytes.

    PubMed

    Gorris, Raphaela; Fischer, Julia; Erwes, Kim Lina; Kesavan, Jaideep; Peterson, Daniel A; Alexander, Michael; Nöthen, Markus M; Peitz, Michael; Quandel, Tamara; Karus, Michael; Brüstle, Oliver

    2015-12-01

    Neural precursor cells (NPCs) derived from human pluripotent stem cells (hPSCs) represent an attractive tool for the in vitro generation of various neural cell types. However, the developmentally early NPCs emerging during hPSC differentiation typically show a strong propensity for neuronal differentiation, with more limited potential for generating astrocytes and, in particular, for generating oligodendrocytes. This phenomenon corresponds well to the consecutive and protracted generation of neurons and GLIA during normal human development. To obtain a more gliogenic NPC type, we combined growth factor-mediated expansion with pre-exposure to the differentiation-inducing agent retinoic acid and subsequent immunoisolation of CD133-positive cells. This protocol yields an adherent and self-renewing population of hindbrain/spinal cord radial glia (RG)-like neural precursor cells (RGL-NPCs) expressing typical neural stem cell markers such as nestin, ASCL1, SOX2, and PAX6 as well as RG markers BLBP, GLAST, vimentin, and GFAP. While RGL-NPCs maintain the ability for tripotential differentiation into neurons, astrocytes, and oligodendrocytes, they exhibit greatly enhanced propensity for oligodendrocyte generation. Under defined differentiation conditions promoting the expression of the major oligodendrocyte fate-determinants OLIG1/2, NKX6.2, NKX2.2, and SOX10, RGL-NPCs efficiently convert into NG2-positive oligodendroglial progenitor cells (OPCs) and are subsequently capable of in vivo myelination. Representing a stable intermediate between PSCs and OPCs, RGL-NPCs expedite the generation of PSC-derived oligodendrocytes with O4-, 4860-, and myelin basic protein (MBP)-positive cells that already appear within 7 weeks following growth factor withdrawal-induced differentiation. Thus, RGL-NPCs may serve as robust tool for time-efficient generation of human oligodendrocytes from embryonic and induced pluripotent stem cells.

  16. A comparative reliability and performance study of different stent designs in terms of mechanical properties: foreshortening, recoil, radial force, and flexibility.

    PubMed

    Kim, Dong Bin; Choi, Hyuk; Joo, Sang Min; Kim, Han Ki; Shin, Jae Hee; Hwang, Min Ho; Choi, Jaesoon; Kim, Dong-Gon; Lee, Kwang Ho; Lim, Chun Hak; Yoo, Sun Kook; Lee, Heung-Man; Sun, Kyung

    2013-04-01

    This study seeks to improve the mechanical performance of stents by conducting reliability performance testing and finite element method (FEM)-based simulations for coronary stents. Three commercially available stent designs and our own new design were tested to measure the factors affecting performance, specifically foreshortening, recoil, radial force, and flexibility. The stents used in the present experiments were 3 mm in working diameter and 18 mm of working length. The results of the experiments indicate that the foreshortening of stents A, B, C, and our new design, D, was equivalent to 2.25, 0.67, 0.46, and 0.41%, respectively. The recoil of stents A, B, C, and D was 6.00, 4.35, 3.50, and 4.36%, respectively. Parallel plate radial force measurements were A, 3.72 ± 0.28 N; B, 3.81 ± 0.32 N; C, 4.35 ± 0.18 N; and D, 4.02 ± 0.24 N. Radial forces determined by applying uniform pressure in the circumferential direction were A, 28.749 ± 0.81 N; B, 32.231 ± 1.80 N; C, 34.522 ± 3.06 N; and D, 42.183 ± 2.84 N. The maximum force of crimped stent at 2.2-mm deflection was 1.01 ± 0.08 N, 0.82 ± 0.08 N, 0.92 ± 0.12 N, and 0.68 ± 0.07 N for each of stents A, B, C and D. The results of this study enabled us to identify several factors to enhance the performance of stents. In comparing these stents, we found that our design, stent D, which was designed by a collaborative team from seven universities, performed better than the commercial stents across all parameter of foreshortening, recoil, radial force, and flexibility.

  17. Accurate determination of pyridine-poly(amidoamine) dendrimer absolute binding constants with the OPLS-AA force field and direct integration of radial distribution functions.

    PubMed

    Peng, Yong; Kaminski, George A

    2005-08-11

    OPLS-AA force field and direct integration of intermolecular radial distribution functions (RDF) were employed to calculate absolute binding constants of pyridine molecules to amino group (NH2) and amide group hydrogen atoms in and first generation poly(amidoamine) dendrimers in chloroform. The average errors in the absolute and relative association constants, as predicted with the calculations, are 14.1% and 10.8%, respectively, which translate into ca. 0.08 and 0.06 kcal/mol errors in the absolute and relative binding free energies. We believe that this level of accuracy proves the applicability of the OPLS-AA, force field, in combination with the direct RDF integration, to reproducing and predicting absolute intermolecular association constants of low magnitudes (ca. 0.2-2.0 range).

  18. Accurate Determination of Pyridine -- Poly (Amidoamine) Dendrimer Absolute Binding Constants with the OPLS-AA Force Field and Direct Integration of Radial Distribution Functions

    NASA Astrophysics Data System (ADS)

    Peng, Yong; Kaminski, George

    2006-03-01

    OPLS-AA force field and direct integration of intermolecular radial distribution functions (RDF) were employed to calculate absolute binding constants of pyridine molecules to NH2 and amide group hydrogen atoms in 0th and 1st generation poly (amidoamine) dendrimers in chloroform. The average errors in the absolute and relative association constants, as predicted with the calculations, are 14.1% and 10.8%, respectively, which translate into ca. 0.08 kcal/mol and 0.06 kcal/mol errors in the absolute and relative binding free energies. We believe that this level of accuracy proves the applicability of the OPLS-AA, force field, in combination with the direct RDF integration, to reproducing and predicting absolute intermolecular association constants of low magnitudes (ca. 0.2 -- 2.0 range).

  19. A Simple Adaptive Transfer Function for Deriving the Central Blood Pressure Waveform from a Radial Blood Pressure Waveform.

    PubMed

    Gao, Mingwu; Rose, William C; Fetics, Barry; Kass, David A; Chen, Chen-Huan; Mukkamala, Ramakrishna

    2016-09-14

    Generalized transfer functions (GTFs) are available to compute the more relevant central blood pressure (BP) waveform from a more easily measured radial BP waveform. However, GTFs are population averages and therefore may not adapt to variations in pulse pressure (PP) amplification (ratio of radial to central PP). A simple adaptive transfer function (ATF) was developed. First, the transfer function is defined in terms of the wave travel time and reflection coefficient parameters of an arterial model. Then, the parameters are estimated from the radial BP waveform by exploiting the observation that central BP waveforms exhibit exponential diastolic decays. The ATF was assessed using the original data that helped popularize the GTF. These data included radial BP waveforms and invasive reference central BP waveforms from cardiac catheterization patients. The data were divided into low, middle, and high PP amplification groups. The ATF estimated central BP with greater accuracy than GTFs in the low PP amplification group (e.g., central systolic BP and PP root-mean-square-errors of 3.3 and 4.2 mm Hg versus 6.2 and 7.1 mm Hg; p ≤ 0.05) while showing similar accuracy in the higher PP amplification groups. The ATF may permit more accurate, non-invasive central BP monitoring in elderly and hypertensive patients.

  20. A Simple Adaptive Transfer Function for Deriving the Central Blood Pressure Waveform from a Radial Blood Pressure Waveform

    PubMed Central

    Gao, Mingwu; Rose, William C.; Fetics, Barry; Kass, David A.; Chen, Chen-Huan; Mukkamala, Ramakrishna

    2016-01-01

    Generalized transfer functions (GTFs) are available to compute the more relevant central blood pressure (BP) waveform from a more easily measured radial BP waveform. However, GTFs are population averages and therefore may not adapt to variations in pulse pressure (PP) amplification (ratio of radial to central PP). A simple adaptive transfer function (ATF) was developed. First, the transfer function is defined in terms of the wave travel time and reflection coefficient parameters of an arterial model. Then, the parameters are estimated from the radial BP waveform by exploiting the observation that central BP waveforms exhibit exponential diastolic decays. The ATF was assessed using the original data that helped popularize the GTF. These data included radial BP waveforms and invasive reference central BP waveforms from cardiac catheterization patients. The data were divided into low, middle, and high PP amplification groups. The ATF estimated central BP with greater accuracy than GTFs in the low PP amplification group (e.g., central systolic BP and PP root-mean-square-errors of 3.3 and 4.2 mm Hg versus 6.2 and 7.1 mm Hg; p ≤ 0.05) while showing similar accuracy in the higher PP amplification groups. The ATF may permit more accurate, non-invasive central BP monitoring in elderly and hypertensive patients. PMID:27624389

  1. Radial forces of stents used in thoracic endovascular aortic repair and bare self-expanding nitinol stents measured ex vivo - Rapid rescue for obstruction of the innominate artery using bare self-expanding nitinol stents.

    PubMed

    Matsumoto, Takuya; Inoue, Kentaro; Tanaka, Shinichi; Aoyagi, Yukihiko; Matsubara, Yutaka; Matsuda, Daisuke; Yoshiya, Keiji; Yoshiga, Ryosuke; Ohkusa, Tomoko; Maehara, Yoshihiko

    2017-02-01

    Purpose Our objective was to compare the radial forces of several stents ex vivo to identify stents suitable for rescue of the unexpected coverage of aortic arch branches in thoracic endovascular aortic repair. Methods We measured the radial forces of two types of self-expanding bare nitinol stents (E-luminexx and Epic) used singly or as double-walled pairs, and of three endoprostheses used in thoracic endovascular aortic repair (TEVAR, Gore c-TAG, Relay, and Valiant) by compressing the stent using an MTS Instron universal testing machine (model #5582). We also examined the compressive effects of the TEVAR endoprostheses and the bare nitinol stents on each other. Results The radial force was greater in the center than at the edge of each stent. In all stents tested, the radial force decreased incrementally with increasing stent diameter. The radial force at the center was two times greater when using two stents than with a single stent. In the compression test, only E-luminexx used as a pair was not compressed after compressing a Relay endoprosthesis by 12 mm. Conclusion Two E-luminexx stents are appropriate to restore the blood flow if a TEVAR endoprosthesis covers the innominate artery following innominate-carotid-left subclavian arterial bypass.

  2. Derivation of Equivalent Continuous Dilution for Cyclic, Unsteady Driving Forces

    SciTech Connect

    Lawrence Berkeley National Laboratory; Technical University of Denmark, Department of Civil Engineering; Mortensen, Dorthe K.; Walker, Iain S.; Sherman, Max H.

    2010-12-15

    This article uses an analytical approach to determine the dilution of an unsteadily-generated solute in an unsteady solvent stream, under cyclic temporal boundary conditions. The goal is to find a simplified way of showing equivalence of such a process to a reference case where equivalent dilution is defined as a weighted average concentration. This derivation has direct applications to the ventilation of indoor spaces where indoor air quality and energy consumption cannot in general be simultaneously optimized. By solving the equation we can specify how much air we need to use in one ventilation pattern compared to another to obtain same indoor air quality. Because energy consumption is related to the amount of air exchanged by a ventilation system, the equation can be used as a first step to evaluate different ventilation patterns effect on the energy consumption. The use of the derived equation is demonstrated by representative cases of interest in both residential and non-residential buildings.

  3. The Relationship Between Sea Breeze Forcing and HF Radar-Derived Surface Currents in Monterey Bay

    DTIC Science & Technology

    2014-06-01

    BETWEEN SEA BREEZE FORCING AND HF RADAR-DERIVED SURFACE CURRENTS IN MONTEREY BAY by Emre Tukenmez June 2014 Thesis Advisor: Jeffrey D...2014 3. REPORT TYPE AND DATES COVERED Master’s Thesis 4. TITLE AND SUBTITLE THE RELATIONSHIP BETWEEN SEA BREEZE FORCING AND HF RADAR- DERIVED...importance of sea breeze , only Hendrickson and MacMahan’s research has been done to determine sea breeze effects in Monterey Bay; other than that not

  4. Carbon nanofibers with radially grown graphene sheets derived from electrospinning for aqueous supercapacitors with high working voltage and energy density.

    PubMed

    Zhao, Lei; Qiu, Yejun; Yu, Jie; Deng, Xianyu; Dai, Chenglong; Bai, Xuedong

    2013-06-07

    Improvement of energy density is an urgent task for developing advanced supercapacitors. In this paper, aqueous supercapacitors with high voltage of 1.8 V and energy density of 29.1 W h kg(-1) were fabricated based on carbon nanofibers (CNFs) and Na2SO4 electrolyte. The CNFs with radially grown graphene sheets (GSs) and small average diameter down to 11 nm were prepared by electrospinning and carbonization in NH3. The radially grown GSs contain between 1 and a few atomic layers with their edges exposed on the surface. The CNFs are doped with nitrogen and oxygen with different concentrations depending on the carbonizing temperature. The supercapacitors exhibit excellent cycling performance with the capacity retention over 93.7% after 5000 charging-discharging cycles. The unique structure, possessing radially grown GSs, small diameter, and heteroatom doping of the CNFs, and application of neutral electrolyte account for the high voltage and energy density of the present supercapacitors. The present supercapacitors are of high promise for practical application due to the high energy density and the advantages of neutral electrolyte including low cost, safety, low corrosivity, and convenient assembly in air.

  5. Systematic derivation of anchoring forces in permafrost-affected bedrock

    NASA Astrophysics Data System (ADS)

    Pläsken, Regina; Keuschnig, Markus; Krautblatter, Michael

    2017-04-01

    High-alpine environments have been demonstrated to react particularly sensitive to recent climate warming. While the thermal response of mountain permafrost to atmospheric warming is usually lagged and attenuated, it is still widely expected to create major engineering problems for high-alpine infrastructures in the foreseeable future. Degradation of permafrost in high alpine regions potentially causes massive negative changes in bearing capacity of affected bedrock/subsoils. Building structures, which are founded on such permafrost-influenced bedrock/subsoils, can be severly damaged by changes in their support conditions. Piles and anchors are the most common engineering measures for the stabilization of such foundation-systems in bedrock . However, despite their frequent use only very limited long term data are available on the mechanical behaviour of anchors in permafrost affected bedrock. This contribution addresses the need for continuous, high-quality data on subsurface conditions in high-alpine locations. At the open-air laboratory Kitzsteinhorn (OPAL) three anchor load plates were installed to measure anchor load and temperature. Rock temperatures up to a depth of 30 m are available from two deep boreholes located in the immediate vicinity. Anchor loads vary significantly between summer and winter. During summer anchor loads stagnate at approximately 450 kN. In autumn anchor load values constantly increase until they reach a maximum of 530 kN in January. Seasonal variations are quantified and physical phenomena and their possible order of magnitude are considered to derive a mechanical model of the system anchor in permafrost affected bedrock.

  6. Seasonal variation of cloud radiative forcing derived from the Earth Radiation Budget Experiment

    NASA Technical Reports Server (NTRS)

    Harrison, E. F.; Minnis, P.; Barkstrom, B. R.; Ramanathan, V.; Cess, R. D.

    1990-01-01

    The impact of clouds on the earth's radiation balance is assessed in terms of longwave, shortwave, and net cloud forcing by using monthly averaged clear-sky and cloudy-sky flux data derived from the NASA Earth Radiation Budget Experiment (ERBE). Emphasis is placed on regional measurements, regional cloud forcing, zonal cloud forcing, and snow and ice contributions. It is shown that the global mean cooling varied from 14 to 21 W/sq m between April 1985 and January 1986; hemispherically, the longwave and shortwave cloud forcing nearly cancel each other in the winter hemisphere, while in the summer the negative shortwave cloud forcing is significantly lower than the longwave cloud forcing, producing a strong cooling. The ERBE data reveal that globally, hemispherically, and zonally, clouds have a significant effect on the radiative heating gradients.

  7. The Sensitivity of Simulated Ocean Biogeochemistry to Forcing Fields Derived from NCEP and MERRA Reanalysis Products

    NASA Technical Reports Server (NTRS)

    Gregg, Watson; Casey, Nancy

    2010-01-01

    Ocean biogeochemistry models are typically forced by atmospheric and oceanic data derived from reanalysis products. For the NASA Ocean Biogeochemistry Model (NOBM) such reanalysis forcing fields include: surface wind stress, sea surface temperature, ice distributions, shortwave radiation, surface wind speeds and surface atmospheric pressure. Additionally, proper computation of ocean irradiance requires reanalysis products of relative humidity and precipitable water (in addition to aerosol and cloud information which is derived from satellite data). The question posed here is, does the choice of reanalysis products make a difference in the representation of ocean biology and biogeochemistry? NOBM was forced by NCEP and MERRA reanalysis products for the period 2002-2009. We find that in 2009 global distributions and abundances of biological variables (total chlorophyll and nutrients) and carbon (dissolved inorganic and organic carbon and surface pCO2) were similar between the two different forcing fields. Global statistical comparisons with satellite and in situ data also showed negligible differences.

  8. Radial engine

    SciTech Connect

    Kmicikiewicz, M.A.

    1988-03-01

    A radial engine is described comprising: a housing; equally spaced openings disposed in ring-like arrangement on the periphery of the housing; a piston and cylinder arrangement in each of the opening, a piston rod for each arrangement fixed to and extending radially inwardly from its respective piston and through its respective opening; shoe means pivotally attached at the other end of each of the piston rod; radial guide means extending in the housing in line with each of the piston rods, and the shoe means provided with guide means followers to ensure radial reciprocal movement of the piston rods and shoe means; and a connecting ring journaled on a crankshaft for circular translation motion in the housing, the ring including a circular rim. Each shoe means includes an arcuate follower member being slidably connected to the rim of the connecting ring.

  9. Derivation of amplitude equations for nonlinear oscillators subject to arbitrary forcing.

    PubMed

    Mayol, Catalina; Toral, Raúl; Mirasso, Claudio R

    2004-06-01

    By using a generalization of the multiple scales technique we develop a method to derive amplitude equations for zero-dimensional forced systems. The method allows to consider either additive or multiplicative forcing terms and can be straightforwardly applied to the case that the forcing is white noise. We give examples of the use of this method to the case of the van der Pol-Duffing oscillator. The writing of the amplitude equations in terms of a Lyapunov potential allow us to obtain an analytical expression for the probability distribution function which reproduces reasonably well the numerical simulation results.

  10. Radial dependence of solar energetic particles derived from the 15 March 2013 solar energetic particle event and global MHD simulation

    SciTech Connect

    Wu, Chin-Chun Plunkett, Simon; Liou, Kan; Wu, S. T.; Dryer, Murray

    2016-03-25

    We study an unusual solar energetic particle (SEP) event that was associated with the coronal mass ejection (CME) on March 15, 2013. Enhancements of the SEP fluxes were first detected by the ACE spacecraft at 14:00 UT, ∼7 hours after the onset of the CME (07:00 UT), and the SEP’s peak intensities were recorded ∼36 hours after the onset of the CME. Our recent study showed that the CME-driven shock Mach number, based on a global three-dimensional (3-D) magnetohydrodynamic (MHD) simulation, is well correlated with the time-intensity of 10-30 MeV and 30-80 MeV protons. Here we focus on the radial dependence (r{sup −α}) of {sup 4}He (3.43-41.2 MeV/n) and O (7.30-89.8 MeV/n) energetic particles from ACE/SIS. It is found that the scaling factor (α) ranges between 2 and 4 for most of the energy channels. We also found that the correlation coefficients tend to increase with SEP energies.

  11. Gravitational self-force in nonvacuum spacetimes: An effective field theory derivation

    NASA Astrophysics Data System (ADS)

    Zimmerman, Peter

    2015-09-01

    In this paper we investigate the motion of small compact objects in nonvacuum spacetimes using methods from effective field theory in curved spacetime. Although a vacuum formulation is sufficient in many astrophysical contexts, there are applications such as the role of the self-force in enforcing cosmic censorship in the context of the overcharging problem, which necessitate an extension into the nonvacuum regime. The defining feature of the self-force problem in nonvacuum spacetimes is the coupling between gravitational and nongravitational field perturbations. The formulation of the self-force problem for nonvacuum spacetimes was recently provided in simultaneous papers by Zimmerman and Poisson [Gravitational self-force in nonvacuum spacetimes, Phys. Rev. D 90, 084030 (2014)] and Linz, Friedmann, and Wiseman [Combined gravitational and electromagnetic self-force on charged particles in electrovac spacetimes, Phys. Rev. D 90, 084031 (2014)]. Here we distinguish ourselves by working with the effective action rather than the field equations. The formalism utilizes the multi-index notation developed by Zimmerman and Poisson [Gravitational self-force in nonvacuum spacetimes, Phys. Rev. D 90, 084030 (2014) to accommodate the coupling between the different fields. Using dimensional regularization, we arrive at a finite expression for the local self-force expressed in terms of multi-index quantities evaluated in the background spacetime. We then apply the formalism to compute the coupled gravitational self-force in two explicit cases. First, we calculate the self-force on a massive particle possessing scalar charge and moving in a scalarvac spacetime. We then derive an expression for the self-force on an electrically charged, massive particle moving in an electrovac spacetime. In both cases, the force is expressed as a sum of local terms involving tensors defined in the background spacetime and evaluated at the current position of the particle, as well as tail integrals

  12. THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY

    EPA Science Inventory

    THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. William F. McDonnell Human Studies Division, NHEERL, U.S. Environmental Protection Agency, RTP, NC 27711.
    Short-term exposure to ozone results in a neurally-mediated decrease in the ab...

  13. THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY

    EPA Science Inventory

    THE EFFECT OF SUBMAXIMAL INHALATION ON MEASURES DERIVED FROM FORCED EXPIRATORY SPIROMETRY. William F. McDonnell Human Studies Division, NHEERL, U.S. Environmental Protection Agency, RTP, NC 27711.
    Short-term exposure to ozone results in a neurally-mediated decrease in the ab...

  14. Radial wedge flange clamp

    DOEpatents

    Smith, Karl H.

    2002-01-01

    A radial wedge flange clamp comprising a pair of flanges each comprising a plurality of peripheral flat wedge facets having flat wedge surfaces and opposed and mating flat surfaces attached to or otherwise engaged with two elements to be joined and including a series of generally U-shaped wedge clamps each having flat wedge interior surfaces and engaging one pair of said peripheral flat wedge facets. Each of said generally U-shaped wedge clamps has in its opposing extremities apertures for the tangential insertion of bolts to apply uniform radial force to said wedge clamps when assembled about said wedge segments.

  15. Satellite-derived aerosol radiative forcing from the 2004 British Columbia wildfires

    USGS Publications Warehouse

    Guo, Song; Leighton, H.

    2008-01-01

    The British Columbia wildfires of 2004 was one of the largest wildfire events in the last ten years in Canada. Both the shortwave and longwave smoke aerosol radiative forcing at the top-of-atmosphere (TOA) are investigated using data from the Moderate Resolution Imaging Spectroradiometer (MODIS) and the Clouds and the Earth's Radiant Energy System (CERES) instruments. Relationships between the radiative forcing fluxes (??F) and wildfire aerosol optical thickness (AOT) at 0.55 ??m (??0.55) are deduced for both noontime instantaneous forcing and diurnally averaged forcing. The noontime averaged instantaneous shortwave and longwave smoke aerosol radiative forcing at the TOA are 45.8??27.5 W m-2 and -12.6??6.9 W m-2, respectively for a selected study area between 62??N and 68??N in latitude and 125??W and 145??W in longitude over three mainly clear-sky days (23-25 June). The derived diurnally averaged smoke aerosol shortwave radiative forcing is 19.9??12.1 W m-2 for a mean ??0.55 of 1.88??0.71 over the same time period. The derived ??F-?? relationship can be implemented in the radiation scheme used in regional climate models to assess the effect of wildfire aerosols.

  16. First principles derived, transferable force fields for CO2 adsorption in Na-exchanged cationic zeolites.

    PubMed

    Fang, Hanjun; Kamakoti, Preeti; Ravikovitch, Peter I; Aronson, Matthew; Paur, Charanjit; Sholl, David S

    2013-08-21

    The development of accurate force fields is vital for predicting adsorption in porous materials. Previously, we introduced a first principles-based transferable force field for CO2 adsorption in siliceous zeolites (Fang et al., J. Phys. Chem. C, 2012, 116, 10692). In this study, we extend our approach to CO2 adsorption in cationic zeolites which possess more complex structures. Na-exchanged zeolites are chosen for demonstrating the approach. These methods account for several structural complexities including Al distribution, cation positions and cation mobility, all of which are important for predicting adsorption. The simulation results are validated with high-resolution experimental measurements of isotherms and microcalorimetric heats of adsorption on well-characterized materials. The choice of first-principles method has a significant influence on the ability of force fields to accurately describe CO2-zeolite interactions. The PBE-D2 derived force field, which performed well for CO2 adsorption in siliceous zeolites, does not do so for Na-exchanged zeolites; the PBE-D2 method overestimates CO2 adsorption energies on multi-cation sites that are common in cationic zeolites with low Si/Al ratios. In contrast, a force field derived from the DFT/CC method performed well. Agreement was obtained between simulation and experiment not only for LTA-4A on which the force field fitting is based, but for other two common adsorbents, NaX and NaY.

  17. Sliding-mode and proportional-derivative-type motion control with radial basis function neural network based estimators for wheeled vehicles

    NASA Astrophysics Data System (ADS)

    Pamosoaji, Anugrah K.; Thuong Cat, Pham; Hong, Keum-Shik

    2014-12-01

    An obstacle avoidance problem of rear-steered wheeled vehicles in consideration of the presence of uncertainties is addressed. Modelling errors and additional uncertainties are taken into consideration. Controller designs for driving and steering motors are designed. A proportional-derivative-type driving motor controller and a sliding-mode steering controller combined with radial basis function neural network (RBFNN) based estimators are proposed. The convergence properties of the RBFNN-based estimators are proven by the Stone-Weierstrass theorem. The stability of the proposed control law is proven using Lyapunov stability analysis. The obstacle avoidance strategy utilising the sliding surface adjustment to an existing navigation method is presented. It is concluded that the driving velocity and steering-angle performances of the proposed control system are satisfactory.

  18. Lithosphere thickness and mantle viscosity estimated from joint inversion of GPS and GRACE-derived radial deformation and gravity rates in North America

    NASA Astrophysics Data System (ADS)

    Zhao, S.

    2013-09-01

    The Global Positioning System (GPS) and the Gravity Recovery and Climate Experiment (GRACE) have been used to respectively determine the Earth's surface deformation and gravity changes associated with glacial isostatic adjustment, which is caused by ongoing stress release of the viscoelastic mantle after removal of the Late Pleistocene ice sheets. Here we present a joint inversion analysis of GPS-derived radial (vertical) deformation and GRACE-derived gravity rates in North America to examine whether the ice sheets (ICE-3G and ICE-5G) and earth models can fit the satellite based observations. The results of joint inversion give an effective lithosphere thickness of 150 km (110-180 km under a statistical confidence level of 80 per cent), an upper-mantle viscosity of 3.7 (2.0-5.0; 90 per cent confidence level) × 1020 Pa s, and a lower-mantle viscosity of 1.9 (1.3-2.6; 90 per cent confidence level) × 1021 Pa s. More sophisticated models such as introducing a transition zone of 400-670 km are not fully resolved with current data sets because there is no significant improvement in fitting observations. Tests of modifying ICE-5G show that a reduction of ice thickness by ˜20 per cent in the area west of Hudson Bay and an increase by ˜40 per cent in the southeast (Quebec region) are required to fit both observed vertical deformation and gravity changes. An additional test from inversion analysis of GRACE-derived geoid rates confirms possible signal loss in the GRACE-derived gravity rates, which could be due to noise reduction methods used in data processing stages.

  19. Possibilities of the regional gravity field recovery from first-, second- and third-order radial derivatives of the disturbing gravitational potential measured on moving platforms

    NASA Astrophysics Data System (ADS)

    Pitonak, Martin; Sprlak, Michal; Novak, Pavel; Tenzer, Robert

    2016-04-01

    Recently realized gravity-dedicated satellite missions allow for measuring values of scalar, vectorial (Gravity Recovery And Climate Experiment - GRACE) and second-order tensorial (Gravity field and steady-state Ocean Circulation Explorer - GOCE) parameters of the Earth's gravitational potential. Theoretical aspects related to using moving sensors for measuring elements of the third-order gravitational tensor are currently under investigation, e.g., the gravity field-dedicated satellite mission OPTIMA (OPTical Interferometry for global Mass change detection from space) should measure third-order derivatives of the Earth's gravitational potential. This contribution investigates regional recovery of the disturbing gravitational potential on the Earth's surface from satellite and aerial observations of the first-, second- and third-order radial derivatives of the disturbing gravitational potential. Synthetic measurements along a satellite orbit at the altitude of 250 km and along an aircraft track at the altitude of 10 km are synthetized from the global gravitational model EGM2008 and polluted by the Gaussian noise. The process of downward continuation is stabilized by the Tikhonov regularization. Estimated values of the disturbing gravitational potential are compared with the same quantity synthesized directly from EGM2008.

  20. Regional Recovery of the Disturbing Gravitational Potential from Satellite Observations of First-, Second- and Third-order Radial Derivatives of the Disturbing Gravitational Potential

    NASA Astrophysics Data System (ADS)

    Novak, P.; Pitonak, M.; Sprlak, M.

    2015-12-01

    Recently realized gravity-dedicated satellite missions allow for measuring values of scalar, vectorial (Gravity Recovery And Climate Experiment - GRACE) and second-order tensorial (Gravity field and steady-state Ocean Circulation Explorer - GOCE) parameters of the Earth's gravitational potential. Theoretical aspects related to using moving sensors for measuring elements of a third-order gravitational tensor are currently under investigation, e.g. the gravity-dedicated satellite mission OPTIMA (OPTical Interferometry for global Mass change detection from space) should measure third-order derivatives of the Earth's gravitational potential. This contribution investigates regional recovery of the disturbing gravitational potential on the Earth's surface from satellite observations of first-, second- and third-order radial derivatives of the disturbing gravitational potential. Synthetic measurements along a satellite orbit at the altitude of 250 km are synthetized from the global gravitational model EGM2008 and polluted by the Gaussian noise. The process of downward continuation is stabilized by the Tikhonov regularization. Estimated values of the disturbing gravitational potential are compared with the same quantity synthesized directly from EGM2008. Finally, this contribution also discusses merging a regional solution into a global field as a patchwork.

  1. Ab initio MO calculation of force constants and dipole derivatives for formamide

    NASA Astrophysics Data System (ADS)

    Sugawara, Yoko; Hamada, Yoshiaki; Hirakawa, Akiko Y.; Tsuboi, Masamichi; Kato, Shigeki; Morokuma, Keiji

    1980-08-01

    Ab initio SCF MO calculations have been carried out for the equilibrium geometry, vibrational frequencies, force constants, dipole moment and its derivatives of formamide. The energy gradient method was employed and the 4-31G basis set was used. For in-plane vibrations: (1) Calculated normal frequencies were 10-20% greater than the observed fundamental frequencies. (2) Isotope shifts (- d0, - d1, - d2, and - d3 species) were well reproduced. (3) The calculated dipole moment derivatives showed a good correspondence with the infrared intensity pattern. (4) The NH 2 rocking—OCN bending cross term, which should be zero in the Urey—Bradley force field, came out to be as large as -0.18 mdyne A. For out-of-plane vibrations, especially for the NH 2 wagging, it was found to be essential to include polarization functions for N, C and O atoms.

  2. Load Absorption Force-Time Characteristics Following the Second Pull of Weightlifting Derivatives.

    PubMed

    Suchomel, Timothy J; Lake, Jason P; Comfort, Paul

    2017-06-01

    The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their 1-repetition maximum HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared with the HPC (p < 0.001; d = 3.77) and JS (p < 0.001; d = 5.48), whereas no difference existed between the HPC and JS (p = 0.573; d = 0.51). The JS produced significantly greater load absorption mean forces compared with the HPC (p < 0.001; d = 2.85) and HHP (p < 0.001; d = 3.75), whereas no difference existed between the HPC and HHP (p = 0.253; d = 0.37). Significantly more load absorption work was performed during the JS compared with the HPC (p < 0.001; d = 5.03) and HHP (p < 0.001; d = 1.69), whereas HHP load absorption work was also significantly greater compared with the HPC (p < 0.001; d = 4.81). The weightlifting pulling derivatives examined in the current study (JS and HHP) produced greater load absorption demands after the second pull compared with the weightlifting catching derivative (HPC). The JS and HHP may be used as effective training stimuli for load absorption during impact tasks such as jumping.

  3. Load absorption force-time characteristics following the second pull of weightlifting derivatives.

    PubMed

    Suchomel, Timothy J; Lake, Jason P; Comfort, Paul

    2016-09-21

    The purpose of this study was to compare the load absorption force-time characteristics of weightlifting catching and pulling derivatives. Twelve resistance-trained men performed repetitions of the hang power clean (HPC), jump shrug (JS), and hang high pull (HHP) on a force platform with 30, 45, 65, and 80% of their one repetition maximum (1RM) HPC. Load absorption phase duration, mean force, and work were calculated from the force-time data. The HHP produced a significantly longer load absorption phase duration compared to the HPC (p < 0.001, d = 3.77) and JS (p < 0.001, d = 5.48), while no difference existed between the HPC and JS (p = 0.573, d = 0.51). The JS produced significantly greater load absorption mean forces compared to the HPC (p < 0.001, d = 2.85) and HHP (p < 0.001, d = 3.75), while no difference existed between the HPC and HHP (p = 0.253, d = 0.37). Significantly more load absorption work was performed during the JS compared to the HPC (p < 0.001, d = 5.03) and HHP (p < 0.001, d = 1.69), while HHP load absorption work was also significantly greater compared to the HPC (p < 0.001, d = 4.81). The weightlifting pulling derivatives examined in the current study (JS and HHP) produced greater load absorption demands following the second pull compared to the weightlifting catching derivative (HPC). The JS and HHP may be used as effective training stimuli for load absorption during impact tasks such as jumping.

  4. Modification of 56ACARBO force field for molecular dynamic calculations of chitosan and its derivatives.

    PubMed

    Naumov, Vladimir S; Ignatov, Stanislav K

    2017-08-01

    The GROMOS 56ACARBO force field for the description of carbohydrates was modified for calculations of chitosan (poly-1,4-(N-acetyl)-β-D-glucopyranosamine-2) with protonated and non-protonated amino groups and its derivatives. Additional parameterization was developed on the basis of quantum chemical calculations. The modified force field (56ACARBO_CHT) allows performing the molecular dynamic calculations of chitosans with different degrees of protonation corresponding to various acidity of medium. Test calculations of the conformational transitions in the chitosan rings and polymeric chains as well as the chitosan nanocrystal dissolution demonstrate good agreement with experimental data. Graphical abstract The GROMOS 56ACARBO_CHT force field allows performing the molecular dynamic calculations of chitosans with different types of amio-group: free, protonated, substituted.

  5. Geometric derivation of the microscopic stress: A covariant central force decomposition

    NASA Astrophysics Data System (ADS)

    Torres-Sánchez, Alejandro; Vanegas, Juan M.; Arroyo, Marino

    2016-08-01

    We revisit the derivation of the microscopic stress, linking the statistical mechanics of particle systems and continuum mechanics. The starting point in our geometric derivation is the Doyle-Ericksen formula, which states that the Cauchy stress tensor is the derivative of the free-energy with respect to the ambient metric tensor and which follows from a covariance argument. Thus, our approach to define the microscopic stress tensor does not rely on the statement of balance of linear momentum as in the classical Irving-Kirkwood-Noll approach. Nevertheless, the resulting stress tensor satisfies balance of linear and angular momentum. Furthermore, our approach removes the ambiguity in the definition of the microscopic stress in the presence of multibody interactions by naturally suggesting a canonical and physically motivated force decomposition into pairwise terms, a key ingredient in this theory. As a result, our approach provides objective expressions to compute a microscopic stress for a system in equilibrium and for force-fields expanded into multibody interactions of arbitrarily high order. We illustrate the proposed methodology with molecular dynamics simulations of a fibrous protein using a force-field involving up to 5-body interactions.

  6. Seasonal variation of surface and atmospheric cloud radiative forcing over the globe derived from satellite data

    NASA Technical Reports Server (NTRS)

    Gupta, Shashi K.; Staylor, W. Frank; Darnell, Wayne L.; Wilber, Anne C.; Ritchey, Nancy A.

    1993-01-01

    Global distributions of surface and atmospheric cloud radiative forcing parameters have been derived using parameterized radiation models with satellite meteorological data from the International Satellite Cloud Climatology Project, and directly measured top-of-atmosphere radiative fluxes from the Earth Radiation Budget Experiment. Specifically, shortwave, longwave, and total cloud forcing at the surface, and column-averaged values of longwave cloud forcing of the atmosphere were derived for the midseasonal months of April, July, and October 1985 and January 1986, covering a complete annual cycle. Seasonal variability is illustrated by comparing the results for July 1985 and January 1986, which represent the seasonal extremes. Surface shortwave cloud forcing is always negative, representing a cooling of the surface, with strongest cooling (-120 to -180 W/sq m) occurring over midlatitude storm tracks of the summer hemisphere. Surface longwave cloud forcing is always positive, representing a warming of the surface, with strongest warming (60 to 75 W/sq m) occurring over storm tracks of the winter hemisphere. Zonal averages show the entire summer hemisphere dominated by shortwave cooling, the middle and high latitudes of the winter hemisphere dominated by longwave warming, and a broad zone of transition in between. The globally averaged total cloud forcing amounts to a cooling throughout the year, ranging from a low of about -12 W/sq m for July 1985 to a high of about -25 W/sq m for January 1986. The longwave cloud forcing of the atmosphere shows a strong warming over deep convective regions in the tropics and a moderate cooling outside the tropics, amounting to a weak cooling (-2 to -5 W/sq m) in the global average. Comparisons of the results with general circulation model simulations show broad qualitative agreement regarding the locations of prominent warming and cooling regions. Quantitative comparisons, on the other hand, show significant differences between the

  7. Seasonal variation of surface and atmospheric cloud radiative forcing over the globe derived from satellite data

    NASA Technical Reports Server (NTRS)

    Gupta, Shashi K.; Staylor, W. Frank; Darnell, Wayne L.; Wilber, Anne C.; Ritchey, Nancy A.

    1993-01-01

    Global distributions of surface and atmospheric cloud radiative forcing parameters have been derived using parameterized radiation models with satellite meteorological data from the International Satellite Cloud Climatology Project, and directly measured top-of-atmosphere radiative fluxes from the Earth Radiation Budget Experiment. Specifically, shortwave, longwave, and total cloud forcing at the surface, and column-averaged values of longwave cloud forcing of the atmosphere were derived for the midseasonal months of April, July, and October 1985 and January 1986, covering a complete annual cycle. Seasonal variability is illustrated by comparing the results for July 1985 and January 1986, which represent the seasonal extremes. Surface shortwave cloud forcing is always negative, representing a cooling of the surface, with strongest cooling (-120 to -180 W/sq m) occurring over midlatitude storm tracks of the summer hemisphere. Surface longwave cloud forcing is always positive, representing a warming of the surface, with strongest warming (60 to 75 W/sq m) occurring over storm tracks of the winter hemisphere. Zonal averages show the entire summer hemisphere dominated by shortwave cooling, the middle and high latitudes of the winter hemisphere dominated by longwave warming, and a broad zone of transition in between. The globally averaged total cloud forcing amounts to a cooling throughout the year, ranging from a low of about -12 W/sq m for July 1985 to a high of about -25 W/sq m for January 1986. The longwave cloud forcing of the atmosphere shows a strong warming over deep convective regions in the tropics and a moderate cooling outside the tropics, amounting to a weak cooling (-2 to -5 W/sq m) in the global average. Comparisons of the results with general circulation model simulations show broad qualitative agreement regarding the locations of prominent warming and cooling regions. Quantitative comparisons, on the other hand, show significant differences between the

  8. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  9. Force.

    ERIC Educational Resources Information Center

    Gamble, Reed

    1989-01-01

    Discusses pupil misconceptions concerning forces. Summarizes some of Assessment of Performance Unit's findings on meaning of (1) force, (2) force and motion in one dimension and two dimensions, and (3) Newton's second law. (YP)

  10. Repair of 20-mm long rabbit radial bone defects using BMP-derived peptide combined with an alpha-tricalcium phosphate scaffold.

    PubMed

    Saito, Atsuhiro; Suzuki, Yoshihisa; Kitamura, Makoto; Ogata, Shin-Ichi; Yoshihara, Yusuke; Masuda, Shingo; Ohtsuki, Chikara; Tanihara, Masao

    2006-06-15

    In previous studies, we have reported that the BMP-2-derived peptide KIPKASSVPTELSAISTLYL, corresponding to BMP-2 residues 73-92, binds to a BMP-2-specific receptor, and elevates both alkaline phosphatase activity and osteocalcin mRNA in the murine mesenchymal cell line, C3H10T1/2. This 73-92 peptide conjugated to a covalently crosslinked alginate gel induced ectopic bone formation in rat calf muscle, and activated osteoblasts to promote the repair of rat tibial bone defects. Here, we report repair of 20-mm long rabbit radial bone defects using the 73-92 peptide combined with a porous alpha-tricalcium phosphate (TCP) scaffold. In vitro, the 73-92 peptide was released from the porous alpha-TCP scaffold over more than one week. In vivo, radiomorphometric analysis showed that the 73-92 peptide combined with the porous alpha-TCP scaffold promoted calcification in the implanted area in a dose-dependent manner, and that 5 mg of the 73-92 peptide induced connection of 20-mm long defects, defects of critical size, 12 weeks after implantation. Histological examination revealed newly formed bone and a marrow cavity in the implanted area. The area of bone denser than 690 mg/cm(3) induced by the 73-92 peptide was nearly equal to that of the contralateral radius.

  11. COFFDROP: A Coarse-Grained Nonbonded Force Field for Proteins Derived from All-Atom Explicit-Solvent Molecular Dynamics Simulations of Amino Acids

    PubMed Central

    2015-01-01

    We describe the derivation of a set of bonded and nonbonded coarse-grained (CG) potential functions for use in implicit-solvent Brownian dynamics (BD) simulations of proteins derived from all-atom explicit-solvent molecular dynamics (MD) simulations of amino acids. Bonded potential functions were derived from 1 μs MD simulations of each of the 20 canonical amino acids, with histidine modeled in both its protonated and neutral forms; nonbonded potential functions were derived from 1 μs MD simulations of every possible pairing of the amino acids (231 different systems). The angle and dihedral probability distributions and radial distribution functions sampled during MD were used to optimize a set of CG potential functions through use of the iterative Boltzmann inversion (IBI) method. The optimized set of potential functions—which we term COFFDROP (COarse-grained Force Field for Dynamic Representation Of Proteins)—quantitatively reproduced all of the “target” MD distributions. In a first test of the force field, it was used to predict the clustering behavior of concentrated amino acid solutions; the predictions were directly compared with the results of corresponding all-atom explicit-solvent MD simulations and found to be in excellent agreement. In a second test, BD simulations of the small protein villin headpiece were carried out at concentrations that have recently been studied in all-atom explicit-solvent MD simulations by Petrov and Zagrovic (PLoS Comput. Biol.2014, 5, e1003638). The anomalously strong intermolecular interactions seen in the MD study were reproduced in the COFFDROP simulations; a simple scaling of COFFDROP’s nonbonded parameters, however, produced results in better accordance with experiment. Overall, our results suggest that potential functions derived from simulations of pairwise amino acid interactions might be of quite broad applicability, with COFFDROP likely to be especially useful for modeling unfolded or intrinsically

  12. Minimum Detectable Change in Medial Tibiofemoral Contact Force Parameters: Derivation and Application to a Load-Altering Intervention.

    PubMed

    Barrios, Joaquin; Willson, John

    2017-04-01

    Medial tibiofemoral joint contact forces can be estimated using musculoskeletal models. To assess change in these forces that accompany load-modifying interventions, minimum detectable change (MDC) thresholds must be established. The primary study purpose was to derive MDCs for medial tibiofemoral peak force and force impulse during walking. The secondary purpose was to identify the proportions of individuals exhibiting reductions greater than these MDCs when walking with lateral foot wedging. Eight healthy individuals provided 3-dimensional gait data over 3 test sessions to serve as inputs for an inverse dynamics-driven medial tibiofemoral contact force model, from which MDCs for peak force and impulse were derived. The MDC was 0.246 BW (8.7%) for peak force and 0.0385 BW∙s (3.7%) for impulse. Then, 25 healthy individuals provided gait data by walking with and without 6° laterally wedged foot orthoses, and the proportion of individuals exhibiting changes in medial tibiofemoral contact peak force and impulse values exceeding the MDC threshold was determined. For impulse and peak force, 52% and 4% of participants exhibited a decrease exceeding the MDC, respectively. In summary, medial tibiofemoral contact force MDCs were derived, with impulse showing greater sensitivity than peak force to the effects of a biomechanical intervention.

  13. A molecular mechanics valence force field for sulfonamides derived by ab initio methods

    SciTech Connect

    Nicholas, J.B.; Burke, B.J.; Hopfinger, A.J. ); Vance, R.; Martin, E. )

    1991-11-28

    Molecular mechanics valence force field parameters for the sulfonamide group, SO[sub 2]NH, have been derived from ab initio calculations at the RHF/6-31G* level of theory. The force field parameters were designed to be used in conjunction with existing parameters from the MM2/MMP2 force field. The new parameters are demonstrated to accurately reproduce the ab initio optimized geometries of four molecules that contain the sulfonamide group. The strategy used in force field parametrization is discussed. The conformational flexibility of the sulfonamide group has been investigated. Calculations at the RHF/6-31G* level reveal the existence of two stable conformers and that interconversion is achieved by nitrogen inversion rather than rotation about the S-N bond. The energetic effects of expanding the basis set to 6-31G** and of including MP2 and MP3 corrections for electron correlation are discussed. The geometries and Mulliken charges for the ab initio optimized structures are also reported.

  14. The force-field derivation and application of explosive/additive interfaces

    NASA Astrophysics Data System (ADS)

    Long, Yao; Chen, Jun

    2016-10-01

    The inter-molecular force-field across RDX/(paraffin, fluoropolymer) interfaces are derived from first-principles calculated energies under the GGA+vdW functional. Based on the force-field, the polycrystal structures of mixture explosives are obtained, and a set of thermodynamic properties are calculated, including the elastic constants, thermal expansion coefficient, heat capacity, isothermal curve and the Hugoniot curve. The results are in good agreement with the available experiments, and provide a reasonable prediction about the properties of plastic bonded explosives. We find that the thermal expansion coefficient of a multi-component explosive is not only determined by the properties of the components, but is also affected by the thermal stress at the explosive/additive interfaces.

  15. Development of a Forced Oscillation System for Measuring Dynamic Derivatives of Fluidic Vehicles

    NASA Technical Reports Server (NTRS)

    Trieu, B. C.; Tyler, T. R.; Stewart, B. K.; Chamock, J. K.; Fisher, D. W.; Heim, E. H.; Brandon, J.; Grafton, S. B.

    2006-01-01

    A new Forced Oscillation System (FOS) has been designed and built at NASA Langley Research Center that provides new capabilities for aerodynamic researchers to investigate the dynamic derivatives of vehicle configurations. Test vehicles may include high performance and general aviation aircraft, re-entry spacecraft, submarines and other fluidic vehicles. The measured data from forced oscillation testing is used in damping characteristic studies and in simulation databases for control algorithm development and performance analyses. The newly developed FOS hardware provides new flexibility for conducting dynamic derivative studies. The design is based on a tracking principle where a desired motion profile is achieved via a fast closed-loop positional controller. The motion profile for the tracking system is numerically generated and thus not limited to sinusoidal motion. This approach permits non-traditional profiles such as constant velocity and Schroeder sweeps. Also, the new system permits changes in profile parameters including nominal offset angle, waveform, and associated parameters such as amplitude and frequency. Most importantly, the changes may be made remotely without halting the FOS and the tunnel. System requirements, system analysis, and the resulting design are addressed for a new FOS in the 12-Foot Low-Speed Wind Tunnel (LSWT). The overall system including mechanical, electrical, and control subsystems is described. The design is complete, and the FOS has been built and installed in the 12-Foot LSWT. System integration and testing have verified design intent and safe operation. Currently it is being validated for wind-tunnel operations and aerodynamic testing. The system is a potential major enhancement to forced oscillation studies. The productivity gain from the motion profile automation will shorten the testing cycles needed for control surface and aircraft control algorithm development. The new motion capabilities also will serve as a test bed for

  16. Balanced radial engine

    SciTech Connect

    Goldowsky, M.P.

    1991-04-02

    This patent describes an internal combustion radial engine composed of an even number of identical and fully functional single cylinder slider crank 2-cycle or 4-cycle engines. It comprises a piston, linkage means, carburetor means, and shaft, the engines being positioned in pairs in a common plane, the pistons are in line and diametrally opposed, the engine shafts are parallel to one another and to a central output shaft and having synchronized means positioned on the engine shafts for coupling the engine shafts to the output shaft whereby diametrally opposite pistons and linkage means inertial forces, the output shaft projections from the synchronizing means past a front of the radial engine and the engine shafts project from the engines to the synchronizing means opposite in direction to the output shaft.

  17. Radial-radial single rotor turbine

    SciTech Connect

    Platts, David A.

    2006-05-16

    A rotor for use in turbine applications has a radial compressor/pump having radially disposed spaced apart fins forming passages and a radial turbine having hollow turbine blades interleaved with the fins and through which fluid from the radial compressor/pump flows. The rotor can, in some applications, be used to produce electrical power.

  18. On the use of the proximity force approximation for deriving limits to short-range gravitational-like interactions from sphere-plane Casimir force experiments

    SciTech Connect

    Dalvit, Diego A. R.; Onofrio, Roberto

    2009-09-15

    We discuss the role of the proximity force approximation in deriving limits to the existence of Yukawian forces--predicted in the submillimeter range by many unification models--from Casimir force experiments using the sphere-plane geometry. Two forms of this approximation are discussed, the first used in most analyses of the residuals from the Casimir force experiments performed so far, and the second recently discussed in this context in R. Decca et al.[Phys. Rev. D 79, 124021 (2009)]. We show that the former form of the proximity force approximation overestimates the expected Yukawa force and that the relative deviation from the exact Yukawa force is of the same order of magnitude, in the realistic experimental settings, as the relative deviation expected between the exact Casimir force and the Casimir force evaluated in the proximity force approximation. This implies both a systematic shift making the actual limits to the Yukawa force weaker than claimed so far, and a degree of uncertainty in the {alpha}-{lambda} plane related to the handling of the various approximations used in the theory for both the Casimir and the Yukawa forces. We further argue that the recently discussed form for the proximity force approximation is equivalent, for a geometry made of a generic object interacting with an infinite planar slab, to the usual exact integration of any additive two-body interaction, without any need to invoke approximation schemes. If the planar slab is of finite size, an additional source of systematic error arises due to the breaking of the planar translational invariance of the system, and we finally discuss to what extent this may affect limits obtained on power-law and Yukawa forces.

  19. Radial systems of dark globules

    SciTech Connect

    Gyul'budagyn, A.L.

    1986-03-01

    The author gives examples of radial systems consisting of dark globules and ''elephant trunks''. Besides already known systems, which contain hot stars at their center, data are given on three radial systems of a new kind, at the center of which there are stars of spectral types later than B. Data are given on 32 globules of radial systems of the association Cep OB2. On the basis of the observational data, it is concluded that at least some of the isolated Bok globules derive from elephant trunks and dark globules forming radial systems around hot stars. It is also suggested that the two molecular clouds situated near the Rosette nebula and possessing velocities differing by ca 20 km/sec from the velocity of the nebula could have been ejected in opposite directions from the center of the nebula. One of these clouds consists of dark globules forming the radial system of the Rosette nebula.

  20. A novel integrated 4-DOF radial hybrid magnetic bearing for MSCMG

    NASA Astrophysics Data System (ADS)

    Jinji, Sun; Ziyan, Ju; Weitao, Han; Gang, Liu

    2017-01-01

    This paper proposes a novel integrated radial hybrid magnetic bearing (RHMB) for application with the small-sized magnetically suspended control moment gyroscope (MSCMG), which can control four degrees of freedom (4-DOFs), including two radial translational DOFs and two radial tilting DOFs, and provide the axial passive resilience. The configuration and working principle of the RHMB are introduced. Mathematical models of radial force, axial resilience and moment are established by using equivalent magnetic circuit method (EMCM), from which the radial force-radial displacement, radial force-current relationships are derived, as well as axial resilience-axial displacement, moment-tilting angle and moment-current. Finite element method (FEM) is also applied to analyze the performance and characteristics of the RHMB. The analysis results are in good agreement with that calculated by the EMCM, which is helpful in designing, optimizing and controlling the RHMB. The comparisons between the performances of the integrated 4-DOF RHMB and the traditional 4-DOF RHMB are made. The contrast results indicate that the proposed integrated 4-DOF RHMB possesses better performance compared to the traditional structure, such as copper loss, current stiffness, and tilting current stiffness.

  1. Radial Erosion

    NASA Technical Reports Server (NTRS)

    2005-01-01

    [figure removed for brevity, see original site]

    The ejecta surrounding the crater (off image to the left) in this image has undergone significant erosion by the wind. The wind has stripped the surface features from the ejecta and has started to winnow away the ejecta blanket. Near the margin of the ejecta the wind is eroding along a radial pattern -- taking advantage of radial emplacement. Note the steep margin of the ejecta blanket. Most, if not all, of the fine ejecta material has been removed and the wind in now working on the more massive continuous ejecta blanket.

    Image information: VIS instrument. Latitude 12.5, Longitude 197.4 East (162.6 West). 37 meter/pixel resolution.

    Note: this THEMIS visual image has not been radiometrically nor geometrically calibrated for this preliminary release. An empirical correction has been performed to remove instrumental effects. A linear shift has been applied in the cross-track and down-track direction to approximate spacecraft and planetary motion. Fully calibrated and geometrically projected images will be released through the Planetary Data System in accordance with Project policies at a later time.

    NASA's Jet Propulsion Laboratory manages the 2001 Mars Odyssey mission for NASA's Office of Space Science, Washington, D.C. The Thermal Emission Imaging System (THEMIS) was developed by Arizona State University, Tempe, in collaboration with Raytheon Santa Barbara Remote Sensing. The THEMIS investigation is led by Dr. Philip Christensen at Arizona State University. Lockheed Martin Astronautics, Denver, is the prime contractor for the Odyssey project, and developed and built the orbiter. Mission operations are conducted jointly from Lockheed Martin and from JPL, a division of the California Institute of Technology in Pasadena.

  2. Relativistic version of the Feynman-Dyson-Hughes derivation of the Lorentz force law and Maxwell's homogeneous equations

    NASA Astrophysics Data System (ADS)

    Essén, Hanno; Nordmark, Arne B.

    2016-09-01

    The canonical Poisson bracket algebra of four-dimensional relativistic mechanics is used to derive the equation of motion for a charged particle, with the Lorentz force, and the homogeneous Maxwell equations.

  3. On the Problem of Theoretical Pressure of a Radial-Flow Pump Unit

    NASA Astrophysics Data System (ADS)

    Pavlechko, V. N.; Protasov, S. K.

    2014-11-01

    An analysis has been made of the velocity of motion of a medium in the wheel of a radial-flow pump unit under the action of a centrifugal force and overcoming the medium's inertial force with its blades. Relations for the pressure produced by the radial-flow pump unit as a function of the angle of inclination of its blades have been derived. The well-known Euler equation describing the dynamic pressure of the radial-flow pump unit has been supplemented to determine its static pressure. An analysis of the obtained results has shown that the pressure of the radial-flow pump unit is maximum at an angle of inclination of its blades of 110o and negative at 140o or larger angles.

  4. Strategy to use the Terra Aerosol Information to Derive the Global Aerosol Radiative Forcing of Climate

    NASA Technical Reports Server (NTRS)

    Kaufman, Yoram J.; Tanre, Didier; Einaudi, Franco (Technical Monitor)

    2000-01-01

    Terra will derive the aerosol optical thickness and properties. The aerosol properties can be used to distinguish between natural and human-made aerosol. In the polar orbit Terra will measure aerosol only once a day, around 10:30 am. How will we use this information to study the global radiative impacts of aerosol on climate? We shall present a strategy to address this problem. It includes the following steps: - From the Terra aerosol optical thickness and size distribution model we derive the effect of aerosol on reflection of solar radiation at the top of the atmosphere. In a sensitivity study we show that the effect of aerosol on solar fluxes can be derived 10 times more accurately from the MODIS data than derivation of the optical thickness itself. Applications to data over several regions will be given. - Using 1/2 million AERONET global data of aerosol spectral optical thickness we show that the aerosol optical thickness and properties during the Terra 10:30 pass are equivalent to the daily average. Due to the aerosol lifetime of several days measurements at this time of the day are enough to assess the daily impact of aerosol on radiation. - Aerosol impact on the top of the atmosphere is only part of the climate question. The INDOEX experiment showed that addressing the impact of aerosol on climate, requires also measurements of the aerosol forcing at the surface. This can be done by a combination of measurements of MODIS and AERONET data.

  5. Enhanced bone formation in large segmental radial defects by combining adipose-derived stem cells expressing bone morphogenetic protein 2 with nHA/RHLC/PLA scaffold.

    PubMed

    Hao, Wei; Dong, Jinlei; Jiang, Ming; Wu, Junwei; Cui, Fuzhai; Zhou, Dongsheng

    2010-12-01

    In this study, rabbit adipose-derived stem cells (rASCs) were isolated, cultured in vitro, and transfected with recombinant adenovirus vector containing human bone morphogenetic protein 2 (Ad-hBMP2). These cells were combined with a nano-hydroxyapatite/recombinant human-like collagen/poly(lactic acid) scaffold (nHA/RHLC/PLA) to fabricate a new biocomposite (hBMP2/rASCs-nHA/RHLC/PLA, group 1) and cultured in osteogenic medium. Non-transfected rASCs mixed with nHA/RHLC/PLA (rASCs-nHA/RHLC/PLA, group 2) and nHA/RHLC/PLA scaffold alone (group 3) served as controls. Scanning electron microscope (SEM) demonstrated integration of rASCs with the nHA/RHLC/PLA scaffold. Quantitative real-time RT-PCR analyses of collagen I, osteonectin, and osteopontin cDNA expression indicated that the osteogenic potency of rASCs was enhanced by transfection with Ad-hBMP2. After in vitro culture for seven days, three groups were implanted into 15-mm length critical-sized segmental radial defects in rabbits. After 12 weeks, radiographic and histological analyses were performed. In group 1, the medullary cavity was recanalised, bone was rebuilt and moulding was finished, the bone contour had begun to remodel and scaffold was degraded completely. In contrast, bone defects were not repaired in groups 2 or 3. Furthermore, the scaffold degradation rate in group 1 was significantly higher than in groups 2 or 3. In summary, after transduction with Ad-hBMP2, the osteogenesis of rASCs was enhanced; a new biocomposite created with these cells induced repair of a critical bone defect in vivo in a relatively short time.

  6. Comparison of immature and mature bone marrow-derived dendritic cells by atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Xing, Feiyue; Wang, Jiongkun; Hu, Mingqian; Yu, Yu; Chen, Guoliang; Liu, Jing

    2011-07-01

    A comparative study of immature and mature bone marrow-derived dendritic cells (BMDCs) was first performed through an atomic force microscope (AFM) to clarify differences of their nanostructure and adhesion force. AFM images revealed that the immature BMDCs treated by granulocyte macrophage-colony stimulating factor plus IL-4 mainly appeared round with smooth surface, whereas the mature BMDCs induced by lipopolysaccharide displayed an irregular shape with numerous pseudopodia or lamellapodia and ruffles on the cell membrane besides becoming larger, flatter, and longer. AFM quantitative analysis further showed that the surface roughness of the mature BMDCs greatly increased and that the adhesion force of them was fourfold more than that of the immature BMDCs. The nano-features of the mature BMDCs were supported by a high level of IL-12 produced from the mature BMDCs and high expression of MHC-II on the surface of them. These findings provide a new insight into the nanostructure of the immature and mature BMDCs.

  7. Radial Halbach Magnetic Bearings

    NASA Technical Reports Server (NTRS)

    Eichenberg, Dennis J.; Gallo, Christopher A.; Thompson, William K.

    2009-01-01

    Radial Halbach magnetic bearings have been investigated as part of an effort to develop increasingly reliable noncontact bearings for future high-speed rotary machines that may be used in such applications as aircraft, industrial, and land-vehicle power systems and in some medical and scientific instrumentation systems. Radial Halbach magnetic bearings are based on the same principle as that of axial Halbach magnetic bearings, differing in geometry as the names of these two types of bearings suggest. Both radial and axial Halbach magnetic bearings are passive in the sense that unlike most other magnetic bearings that have been developed in recent years, they effect stable magnetic levitation without need for complex active control. Axial Halbach magnetic bearings were described in Axial Halbach Magnetic Bearings (LEW-18066-1), NASA Tech Briefs, Vol. 32, No. 7 (July 2008), page 85. In the remainder of this article, the description of the principle of operation from the cited prior article is recapitulated and updated to incorporate the present radial geometry. In simplest terms, the basic principle of levitation in an axial or radial Halbach magnetic bearing is that of the repulsive electromagnetic force between (1) a moving permanent magnet and (2) an electric current induced in a stationary electrical conductor by the motion of the magnetic field. An axial or radial Halbach bearing includes multiple permanent magnets arranged in a Halbach array ("Halbach array" is defined below) in a rotor and multiple conductors in the form of wire coils in a stator, all arranged so the rotary motion produces an axial or radial repulsion that is sufficient to levitate the rotor. A basic Halbach array (see Figure 1) consists of a row of permanent magnets, each oriented so that its magnetic field is at a right angle to that of the adjacent magnet, and the right-angle turns are sequenced so as to maximize the magnitude of the magnetic flux density on one side of the row while

  8. Asymptotics of radial wave equations

    SciTech Connect

    Morehead, J.J.

    1995-10-01

    The Langer modification is an improvement in the WKB analysis of the radial Schroedinger equation. We derive a generalization of the Langer modification to any radial operator. For differential operators we write the modified classical symbols explicitly and show that the WKB wavefunctions with the modification have the exact limiting behavior for small radius. Unlike in the Schroedinger case, generally the modified radial analysis is not equivalent to the WKB analysis of the full problem before reduction by the spherical symmetry. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  9. Investigation of polymer derived ceramics cantilevers for application of high speed atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Wu, Chia-Yun

    High speed Atomic Force Microscopy (AFM) has a wide variety of applications ranging from nanomanufacturing to biophysics. In order to have higher scanning speed of certain AFM modes, high resonant frequency cantilevers are needed; therefore, the goal of this research is to investigate using polymer derived ceramics for possible applications in making high resonant frequency AFM cantilevers using complex cross sections. The polymer derived ceramic that will be studied, is silicon carbide. Polymer derived ceramics offer a potentially more economic fabrication approach for MEMS due to their relatively low processing temperatures and ease of complex shape design. Photolithography was used to make the desired cantilever shapes with micron scale size followed by a wet etching process to release the cantilevers from the substrates. The whole manufacturing process we use borrow well-developed techniques from the semiconducting industry, and as such this project also could offer the opportunity to reduce the fabrication cost of AFM cantilevers and MEMS in general. The characteristics of silicon carbide made from the precursor polymer, SMP-10 (Starfire Systems), were studied. In order to produce high qualities of silicon carbide cantilevers, where the major concern is defects, proper process parameters needed to be determined. Films of polymer derived ceramics often have defects due to shrinkage during the conversion process. Thus control of defects was a central issue in this study. A second, related concern was preventing oxidation; the polymer derived ceramics we chose is easily oxidized during processing. Establishing an environment without oxygen in the whole process was a significant challenge in the project. The optimization of the parameters for using photolithography and wet etching process was the final and central goal of the project; well established techniques used in microfabrication were modified for use in making the cantilever in the project. The techniques

  10. Correlations of the instantaneous carrying force and pressure distribution in the case of the narrow sliding radial bearing under hard shocks

    NASA Astrophysics Data System (ADS)

    Alexandrescu, I. M.; Coteţiu, R.; Darabă, D.

    2017-02-01

    We present the determining relationship of carriage in non-dimensional form for narrow radial bearings subjected to shocks and vibrations, as well as the determining relationships of the lubricant minimum thickness in relation to the dynamic loading. Due to the very short time of loading radial bearings subjected to shocks and vibrations, of about 0.5-1 ms, we consider only the approaching motion between spindle/axle and bushing on the direction of the centre line, without the rotation of the spindle/axle (the case of the non-rotating bearing), so that the effect of the lubricant expulsion be prevalent in the achieving of the self-carrying film. The paper is focused on determining relationship of carriage in dimensional form for narrow radial bearings exposed to shocks and vibrations, as well as the determining relationships of the pressure distribution from the film to be lubricated in various places of the bearing’s body. It is showed the details during the measuring accomplishments and the experimental results are registered in a record of obtained results. This paper was accepted for publication in Proceedings after double peer reviewing process but was not presented at the Conference ROTRIB’16

  11. Pregnancy-induced remodelling and enhanced endothelium-derived hyperpolarization-type vasodilator activity in rat uterine radial artery: transient receptor potential vanilloid type 4 channels, caveolae and myoendothelial gap junctions

    PubMed Central

    Senadheera, Sevvandi; Bertrand, Paul P; Grayson, T Hilton; Leader, Leo; Murphy, Timothy V; Sandow, Shaun L

    2013-01-01

    In pregnancy, the vasculature of the uterus undergoes rapid remodelling to increase blood flow and maintain perfusion to the fetus. The present study determines the distribution and density of caveolae, transient receptor potential vanilloid type 4 channels (TRPV4) and myoendothelial gap junctions, and the relative contribution of related endothelium-dependent vasodilator components in uterine radial arteries of control virgin non-pregnant and 20-day late-pregnant rats. The hypothesis examined is that specific components of endothelium-dependent vasodilator mechanisms are altered in pregnancy-related uterine radial artery remodelling. Conventional and serial section electron microscopy were used to determine the morphological characteristics of uterine radial arteries from control and pregnant rats. TRPV4 distribution and expression was examined using conventional confocal immunohistochemistry, and the contribution of endothelial TRPV4, nitric oxide (NO) and endothelium-derived hyperpolarization (EDH)-type activity determined using pressure myography with pharmacological intervention. Data show outward hypertrophic remodelling occurs in uterine radial arteries in pregnancy. Further, caveolae density in radial artery endothelium and smooth muscle from pregnant rats was significantly increased by ∼94% and ∼31%, respectively, compared with control, whereas caveolae density did not differ in endothelium compared with smooth muscle from control. Caveolae density was significantly higher by ∼59% on the abluminal compared with the luminal surface of the endothelium in uterine radial artery of pregnant rats but did not differ at those surfaces in control. TRPV4 was present in endothelium and smooth muscle, but not associated with internal elastic lamina hole sites in radial arteries. TRPV4 fluorescence intensity was significantly increased in the endothelium and smooth muscle of radial artery of pregnant compared with control rats by ∼2.6- and 5.5-fold

  12. Atomic force microscope observation of branching in single transcript molecules derived from human cardiac muscle

    NASA Astrophysics Data System (ADS)

    Reed, Jason; Hsueh, Carlin; Mishra, Bud; Gimzewski, James K.

    2008-09-01

    We have used an atomic force microscope to examine a clinically derived sample of single-molecule gene transcripts, in the form of double-stranded cDNA, (c: complementary) obtained from human cardiac muscle without the use of polymerase chain reaction (PCR) amplification. We observed a log-normal distribution of transcript sizes, with most molecules being in the range of 0.4-7.0 kilobase pairs (kb) or 130-2300 nm in contour length, in accordance with the expected distribution of mRNA (m: messenger) sizes in mammalian cells. We observed novel branching structures not previously known to exist in cDNA, and which could have profound negative effects on traditional analysis of cDNA samples through cloning, PCR and DNA sequencing.

  13. Air Force use of civil airworthiness criteria for testing and acceptance of military derivative transport aircraft

    SciTech Connect

    Marx, R.I.; Chapman, D.M.; Langley, M.J.; Fouts, R.S.

    1990-01-01

    A review of commercial aircraft programs and the use of FAA certification criteria in the acquisition of off-the-shelf transport aircraft by the USAF to fulfill its airlift requirements is presented. In addition, major differences between military and commercial test programs and acquisition are cited to illustrate the principal benefits to the Air Force of this method. Significantly reduced acquisition time, and reduced ground and flight testing and development costs are shown as benefits of this process. The unique aspects of certification of military derivatives, recent initiatives to codify the processes, and the impacts on changes required in the manner in which the USAF currently contracts for aircraft are discussed. 20 refs.

  14. Capillary Force Seeding of Hydrogels for Adipose-Derived Stem Cell Delivery in Wounds

    PubMed Central

    Garg, Ravi K.; Rennert, Robert C.; Duscher, Dominik; Sorkin, Michael; Kosaraju, Revanth; Auerbach, Lauren J.; Lennon, James; Chung, Michael T.; Paik, Kevin; Nimpf, Johannes; Rajadas, Jayakumar; Longaker, Michael T.

    2014-01-01

    Effective skin regeneration therapies require a successful interface between progenitor cells and biocompatible delivery systems. We previously demonstrated the efficiency of a biomimetic pullulan-collagen hydrogel scaffold for improving bone marrow-derived mesenchymal stem cell survival within ischemic skin wounds by creating a “stem cell niche” that enhances regenerative cytokine secretion. Adipose-derived mesenchymal stem cells (ASCs) represent an even more appealing source of stem cells because of their abundance and accessibility, and in this study we explored the utility of ASCs for hydrogel-based therapies. To optimize hydrogel cell seeding, a rapid, capillary force-based approach was developed and compared with previously established cell seeding methods. ASC viability and functionality following capillary hydrogel seeding were then analyzed in vitro and in vivo. In these experiments, ASCs were seeded more efficiently by capillary force than by traditional methods and remained viable and functional in this niche for up to 14 days. Additionally, hydrogel seeding of ASCs resulted in the enhanced expression of multiple stemness and angiogenesis-related genes, including Oct4, Vegf, Mcp-1, and Sdf-1. Moving in vivo, hydrogel delivery improved ASC survival, and application of both murine and human ASC-seeded hydrogels to splinted murine wounds resulted in accelerated wound closure and increased vascularity when compared with control wounds treated with unseeded hydrogels. In conclusion, capillary seeding of ASCs within a pullulan-collagen hydrogel bioscaffold provides a convenient and simple way to deliver therapeutic cells to wound environments. Moreover, ASC-seeded constructs display a significant potential to accelerate wound healing that can be easily translated to a clinical setting. PMID:25038246

  15. Endothelial differentiation of amniotic fluid-derived stem cells: synergism of biochemical and shear force stimuli.

    PubMed

    Zhang, Ping; Baxter, Jason; Vinod, Kateki; Tulenko, Thomas N; Di Muzio, Paul J

    2009-11-01

    Human amniotic fluid-derived stem (AFS) cells possess several advantages over embryonic and adult stem cells, as evidenced by expression of both types of stem cell markers and ability to differentiate into cells of all three germ layers. Herein, we examine endothelial differentiation of AFS cells in response to growth factors, shear force, and hypoxia. We isolated human AFS cells from amniotic fluid samples (1-4 cc/specimen) obtained from patients undergoing amniocentesis at 15-18 weeks of gestation (n = 10). Isolates maintained in nondifferentiating medium expressed the stem cell markers CD13, CD29, CD44, CD90, CD105, OCT-4, and SSEA-4 through passage 8. After 3 weeks of culture in endothelial growth media-2 (EGM-2), the stem cells exhibited an endothelial-like morphology, formed cord-like structures when plated on Matrigel, and uptook acetylated LDL/lectin. Additionally, mRNA and protein levels of CD31 and von Willebrand factor (vWF) significantly increased in response to culture in EGM-2, with further up-regulation when stimulated by physiological levels (12 dyne/cm(2)) of shear force. Culture in hypoxic conditions (5% O(2)) resulted in significant expression of vascular endothelial growth factor (VEGF) and placental growth factor (PGF) mRNA. This study suggests that AFS cells, isolated from minute amounts of amniotic fluid, acquire endothelial cell characteristics when stimulated by growth factors and shear force, and produce angiogenic factors (VEGF, PGF, and hepatocyte growth factor [HGF]) in response to hypoxia. Thus, amniotic fluid represents a rich source of mesenchymal stem cells potentially suitable for use in cardiovascular regenerative medicine.

  16. Active-Region Twist Derived from Magnetic Tongues and Linear Force-Free Extrapolations

    NASA Astrophysics Data System (ADS)

    Poisson, Mariano; López Fuentes, Marcelo; Mandrini, Cristina H.; Démoulin, Pascal

    2015-11-01

    The main aim of this study is to compare the amount of twist present in emerging active regions (ARs) from photospheric and coronal data. We use linear force-free field models of the observed coronal structure of ARs to determine the global twist. The coronal twist is derived, on one hand, from the force-free parameter [α] of the model and, on the other, from the computed coronal magnetic helicity normalized by the magnetic flux squared. We compare our results, for the same set of ARs, with those of Poisson et al. ( Solar Phys. 290, 727, 2015), in which the twist was estimated using the so-called magnetic tongues observed in line-of-sight magnetograms during AR emergence. We corroborate the agreement between the photospheric and coronal twist-sign and the presence of magnetic tongues as an early proxy of the AR non-potentiality. We find a globally linear relationship between the coronal twist and the one previously deduced for the emerging AR flux rope at the photospheric level. The coronal-twist value is typically lower by a factor of six than the one deduced for the emerging flux rope. We interpret this result as due to the partial emergence of the flux rope that forms the region.

  17. Combination radial and thrust magnetic bearing

    NASA Technical Reports Server (NTRS)

    Blumenstock, Kenneth A. (Inventor)

    2002-01-01

    A combination radial and thrust magnetic bearing is disclosed that allows for both radial and thrust axes control of an associated shaft. The combination radial and thrust magnetic bearing comprises a rotor and a stator. The rotor comprises a shaft, and first and second rotor pairs each having respective rotor elements. The stator comprises first and second stator elements and a magnet-sensor disk. In one embodiment, each stator element has a plurality of split-poles and a corresponding plurality of radial force coils and, in another embodiment, each stator element does not require thrust force coils, and radial force coils are replaced by double the plurality of coils serving as an outer member of each split-pole half.

  18. Differentiation, polarization, and migration of human induced pluripotent stem cell-derived neural progenitor cells co-cultured with a human glial cell line with radial glial-like characteristics.

    PubMed

    Bamba, Yohei; Shofuda, Tomoko; Kanematsu, Daisuke; Nonaka, Masahiro; Yamasaki, Mami; Okano, Hideyuki; Kanemura, Yonehiro

    2014-05-16

    Here we established a unique human glial cell line, GDC90, derived from a human glioma and demonstrated its utility as a glial scaffold for the polarization and differentiation of human induced pluripotent stem cell-derived neural progenitor cells (iPSC-NPCs). When co-cultured with GDC90 cells, iPSC-NPCs underwent rapid polarization and neurite extension along the radially spreading processes of the GDC90 cells, and showed migratory behavior. This method is potentially useful for detailed examination of neurites or for controlling neurites behavior for regenerative medicine. Copyright © 2014 Elsevier Inc. All rights reserved.

  19. Electrostatic Forces: Formulas for the First Derivatives of a Polarizable, Anisotropic Electrostatic Potential Energy Function Based on Machine Learning.

    PubMed

    Mills, Matthew J L; Popelier, Paul L A

    2014-09-09

    Explicit formulas are derived analytically for the first derivatives of a (i) polarizable, (ii) high-rank multipolar electrostatic potential energy function for (iii) flexible molecules. The potential energy function uses a machine learning method called Kriging to predict the local-frame multipole moments of atoms defined via the Quantum Chemical Topology (QCT) approach. These atomic multipole moments then interact via an interaction tensor based on spherical harmonics. Atom-centered local coordinate frames are used, constructed from the internal geometry of the molecular system. The forces involve derivatives of both this geometric dependence and of the trained kriging models. In the near future, these analytical forces will enable molecular dynamics and geometry optimization calculations as part of the QCT force field.

  20. Radial inflow combustor

    SciTech Connect

    Shekleton, J.R.

    1991-12-03

    This paper describes a gas turbine engine. It comprises: radial compressor means for compressing air entering through a compressor inlet opening; axial turbine means in axially spaced relation to the radial compressor means; the radial compressor means being operatively associated with the axial turbine means; radial combustor means intermediate the radial compressor means and axial turbine means; turbine nozzle means proximate the axial turbine means for directing gases of combustion thereto; the radial combustor means including a pair of axially spaced radially extending walls joined at radially outward extremes by a generally cylindrical wall, the walls defining a radial combustion space in communication with both the radial compressor means and the turbine nozzle means, and including means for introducing compressed air into the radial combustion space in a manner avoiding formation of an air film on the generally cylindrical wall.

  1. Fundamental studies of radial wave thermoacoustic engines

    NASA Astrophysics Data System (ADS)

    Arnott, W. P.

    1995-06-01

    Our research is about arbitrary geometry thermoacoustic engines. The specific geometry studied in detail is the radial wave arrangement. Formal theory and the short stack approximation were derived for this geometry and were used to pursue an answer to the following question: Radial or plane wave thermoacoustic refrigerators? To date, the plane wave refrigerator appears to be the best overall compromise refrigerator, though the radial wave refrigerator has a higher cooling capacity. An evolving numerical design program has been enhanced to include radial or plane wave engines with variable plate spacing and both plane and radial wave resonators simultaneously with application to driving radial wave refrigerators with heat driven plane wave sound sources. Our experiments have mainly been aimed at radial wave prime movers for the purposes of validating the theory and investigating the large amplitude behavior. Heat exchanger design is a critical issue.

  2. Very empirical treatment of solvation and entropy: a force field derived from Log Po/w

    NASA Astrophysics Data System (ADS)

    Kellogg, Glen Eugene; Burnett, James C.; Abraham, Donald J.

    2001-04-01

    A non-covalent interaction force field model derived from the partition coefficient of 1-octanol/water solubility is described. This model, HINT for Hydropathic INTeractions, is shown to include, in very empirical and approximate terms, all components of biomolecular associations, including hydrogen bonding, Coulombic interactions, hydrophobic interactions, entropy and solvation/desolvation. Particular emphasis is placed on: (1) demonstrating the relationship between the total empirical HINT score and free energy of association, ΔG interaction; (2) showing that the HINT hydrophobic-polar interaction sub-score represents the energy cost of desolvation upon binding for interacting biomolecules; and (3) a new methodology for treating constrained water molecules as discrete independent small ligands. An example calculation is reported for dihydrofolate reductase (DHFR) bound with methotrexate (MTX). In that case the observed very tight binding, ΔG interaction≤-13.6 kcal mol-1, is largely due to ten hydrogen bonds between the ligand and enzyme with estimated strength ranging between -0.4 and -2.3 kcal mol-1. Four water molecules bridging between DHFR and MTX contribute an additional -1.7 kcal mol-1 stability to the complex. The HINT estimate of the cost of desolvation is +13.9 kcal mol-1.

  3. Generating and characterizing the mechanical properties of cell-derived matrices using atomic force microscopy.

    PubMed

    Tello, Marta; Spenlé, Caroline; Hemmerlé, Joseph; Mercier, Luc; Fabre, Roxane; Allio, Guillaume; Simon-Assmann, Patricia; Goetz, Jacky G

    2016-02-01

    Mechanical interaction between cells and their surrounding extracellular matrix (ECM) controls key processes such as proliferation, differentiation and motility. For many years, two-dimensional (2D) models were used to better understand the interactions between cells and their surrounding ECM. More recently, variation of the mechanical properties of tissues has been reported to play a major role in physiological and pathological scenarios such as cancer progression. The 3D architecture of the ECM finely tunes cellular behavior to perform physiologically relevant tasks. Technical limitations prevented scientists from obtaining accurate assessment of the mechanical properties of physiologically realistic matrices. There is therefore a need for combining the production of high-quality cell-derived 3D matrices (CDMs) and the characterization of their topographical and mechanical properties. Here, we describe methods that allow to accurately measure the young modulus of matrices produced by various cellular types. In the first part, we will describe and review several protocols for generating CDMs matrices from endothelial, epithelial, fibroblastic, muscle and mesenchymal stem cells. We will discuss tools allowing the characterization of the topographical details as well as of the protein content of such CDMs. In a second part, we will report the methodologies that can be used, based on atomic force microscopy, to accurately evaluate the stiffness properties of the CDMs through the quantification of their young modulus. Altogether, such methodologies allow characterizing the stiffness and topography of matrices deposited by the cells, which is key for the understanding of cellular behavior in physiological conditions.

  4. Radial access - be prepared!

    PubMed

    Stathopoulos, Ioannis

    2008-10-01

    We present the case of a 46-year-old female patient that experienced recurrent stent thrombosis and underwent attempted primary PCI via the radial artery. Although radial artery cannulation with a 6 Fr sheath and the diagnostic angiography were successfully performed, the PCI could not be achieved because of failure to advance the 6 Fr guide through the radial artery, due to severe angulation of a high take-off radial artery, combined with a proximal radial artery stenosis.

  5. Improvements in the LLNL objective analysis scheme for deriving forcing fields for single-column models using ARM data

    SciTech Connect

    Leach, M.J.; Yio, J.J.; Cederwall, R.T.

    1997-03-01

    The objective analysis method use for deriving Single-Column Model (SCM) forcing fields with ARM data (Leach, et al., 1996) is undergoing continual improvement. Several improvements were identified at the SCM Workshop held at LLNL in April 1996. These include incorporating large-scale analyses in the objective analysis, and time-filtering input data streams.

  6. Radial stiffness improvement of a flywheel system using multi-surface superconducting levitation

    NASA Astrophysics Data System (ADS)

    Basaran, Sinan; Sivrioglu, Selim

    2017-03-01

    The goal of this research study is the maximization of the levitation force in a flywheel system by the use of more than one permanent magnet with a single ring-shaped HTS material. An analytical model for the radial stiffness of the ring HTS-PM is derived using the frozen image approach. The experimental works are carried out for different polarizations of the permanent magnets, and radial stiffness values are obtained from the radial force measurements. The rotational test of the flywheel system is also realized for different cases. Finally, natural frequencies of the flywheel superconducting magnetic bearing system are experimentally obtained for different combinations of the permanent magnets using a frequency analyzer.

  7. The R.E.D. tools: advances in RESP and ESP charge derivation and force field library building.

    PubMed

    Dupradeau, François-Yves; Pigache, Adrien; Zaffran, Thomas; Savineau, Corentin; Lelong, Rodolphe; Grivel, Nicolas; Lelong, Dimitri; Rosanski, Wilfried; Cieplak, Piotr

    2010-07-28

    Deriving atomic charges and building a force field library for a new molecule are key steps when developing a force field required for conducting structural and energy-based analysis using molecular mechanics. Derivation of popular RESP charges for a set of residues is a complex and error prone procedure because it depends on numerous input parameters. To overcome these problems, the R.E.D. Tools (RESP and ESP charge Derive, ) have been developed to perform charge derivation in an automatic and straightforward way. The R.E.D. program handles chemical elements up to bromine in the periodic table. It interfaces different quantum mechanical programs employed for geometry optimization and computing molecular electrostatic potential(s), and performs charge fitting using the RESP program. By defining tight optimization criteria and by controlling the molecular orientation of each optimized geometry, charge values are reproduced at any computer platform with an accuracy of 0.0001 e. The charges can be fitted using multiple conformations, making them suitable for molecular dynamics simulations. R.E.D. allows also for defining charge constraints during multiple molecule charge fitting, which are used to derive charges for molecular fragments. Finally, R.E.D. incorporates charges into a force field library, readily usable in molecular dynamics computer packages. For complex cases, such as a set of homologous molecules belonging to a common family, an entire force field topology database is generated. Currently, the atomic charges and force field libraries have been developed for more than fifty model systems and stored in the RESP ESP charge DDataBase. Selected results related to non-polarizable charge models are presented and discussed.

  8. The R.E.D. Tools: Advances in RESP and ESP charge derivation and force field library building

    PubMed Central

    Dupradeau, François-Yves; Pigache, Adrien; Zaffran, Thomas; Savineau, Corentin; Lelong, Rodolphe; Grivel, Nicolas; Lelong, Dimitri; Rosanski, Wilfried; Cieplak, Piotr

    2010-01-01

    Deriving atomic charges and building a force field library for a new molecule are key steps when developing a force field required for conducting structural and energy-based analysis using molecular mechanics. Derivation of popular RESP charges for a set of residues is a complex and error prone procedure, because it depends on numerous input parameters. To overcome these problems, the R.E.D. Tools (RESP and ESP charge Derive, http://q4md-forcefieldtools.org/RED/) have been developed to perform charge derivation in an automatic and straightforward way. The R.E.D. program handles chemical elements up to bromine in the periodic table. It interfaces different quantum mechanical programs employed for geometry optimization and computing molecular electrostatic potential(s), and performs charge fitting using the RESP program. By defining tight optimization criteria and by controlling the molecular orientation of each optimized geometry, charge values are reproduced at any computer platform with an accuracy of 0.0001 e. The charges can be fitted using multiple conformations, making them suitable for molecular dynamics simulations. R.E.D. allows also for defining charge constraints during multiple molecule charge fitting, which are used to derive charges for molecular fragments. Finally, R.E.D. incorporates charges into a force field library, readily usable in molecular dynamics computer packages. For complex cases, such as a set of homologous molecules belonging to a common family, an entire force field topology database is generated. Currently, the atomic charges and force field libraries have been developed for more than fifty model systems and stored in the RESP ESP charge DDataBase. Selected results related to non-polarizable charge models are presented and discussed. PMID:20574571

  9. Aerosol Radiative Forcing Derived From SeaWIFS - Retrieved Aerosol Optical Properties

    NASA Technical Reports Server (NTRS)

    Chou, Mong-Dah; Chan, Pui-King; Wang, Menghua; Einaudi, Franco (Technical Monitor)

    2000-01-01

    To understand climatic implications of aerosols over global oceans, the aerosol optical properties retrieved from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) are analyzed, and the effects of the aerosols on the Earth's radiation budgets (aerosol radiative forcing, ARF) are computed using a radiative transfer model. It is found that the distribution of the SeaWiFS-retrieved aerosol optical thickness is distinctively zonal. The maximum in the equatorial region coincides with the Intertropical Convergence Zone, and the maximum in the Southern Hemispheric high latitudes coincides with the region of prevailing westerlies. The minimum aerosol optical thickness is found in the subtropical high pressure regions, especially in the Southern Hemisphere. These zonal patterns clearly demonstrate the influence of atmospheric circulation on the oceanic aerosol distribution. Over global oceans, aerosols reduce the annual mean net downward solar flux by 5.4 W m-2 at the top of the atmosphere and by 6.1 W m-2 at the surface. The largest ARF is found in the tropical Atlantic, Arabian Sea, Bay of Bengal, the coastal regions of Southeast and East Asia, and the Southern Hemispheric high latitudes. During the period of the Indonesian big fires (September-December 1997), the cooling due to aerosols is greater than 15 W m-2 at the top of the atmosphere and greater than 30 W m(exp -1) at the surface in the vicinity of the maritime continents. The atmosphere receives extra solar radiation by greater than 15 W m(exp -1) over a large area. These large changes in radiative fluxes are expected to have enhanced the atmospheric stability, weakened the atmospheric circulation, and augmented the drought condition during that period. It would be very instructive to simulate the regional climatic. The model-calculated clear sky solar flux at the top of the atmosphere is compared with that derived from the Clouds and the Earth's Radiant Energy System (CERES). The net downward solar flux of

  10. Fundamentals studies of radial wave thermoacoustic engines

    NASA Astrophysics Data System (ADS)

    Arnott, W. Patrick

    1994-06-01

    Research on radial wave thermoacoustic sound sources and refrigerators is described. Theoretical analysis and a computer program to implement it, were developed for acoustic quantities such as pressure, particle velocity, etc, and energy fluxes for thermoacoustic engines in the lowest radial mode of a cylindrical resonator. The program is currently most useful for computing prime mover operation both below, at, and beyond onset of oscillation. A short stack approximation was derived to compare the theoretical promise of thermoacoustic engines in the longitudinal and radial standing waves of cylindrical resonators. Results to date indicate radial wave engines are worth pursuing.

  11. Radial reflection diffraction tomography

    NASA Astrophysics Data System (ADS)

    Lehman, Sean K.; Norton, Stephen J.

    2004-10-01

    A wave-based tomographic imaging algorithm based upon a single rotating radially outward oriented transducer is developed. At successive angular locations at a fixed radius, the transducer launches a primary field and collects the backscattered field in a ``pitch/catch'' operation. The hardware configuration, operating mode, and data collection method are identical to that of most medical intravascular ultrasound (IVUS) systems. IVUS systems form images of the medium surrounding the probe based upon ultrasonic B scans, using a straight-ray model of sound propagation. The goal of this research is to develop a wave-based imaging algorithm using diffraction tomography techniques. Given the hardware configuration and the imaging method, this system is referred to as ``radial reflection diffraction tomography.'' Two hardware configurations are considered: a multimonostatic mode using a single transducer as described above, and a multistatic mode consisting of a single transmitter and an aperture formed by multiple receivers. In this latter case, the entire source/receiver aperture rotates about the fixed radius. Practically, such a probe is mounted at the end of a catheter or snaking tube that can be inserted into a part or medium with the goal of forming images of the plane perpendicular to the axis of rotation. An analytic expression for the multimonostatic inverse is derived, but ultimately the new Hilbert space inverse wave (HSIW) algorithm is used to construct images using both operating modes. Applications include improved IVUS imaging, bore hole tomography, and nondestructive evaluation (NDE) of parts with existing access holes. .

  12. Radial Reflection Diffraction Tomography

    SciTech Connect

    Lehman, S K; Norton, S J

    2003-10-10

    We develop a wave-based tomographic imaging algorithm based upon a single rotating radially outward oriented transducer. At successive angular locations at a fixed radius, the transducer launches a primary field and collects the backscattered field in a ''pitch/catch'' operation. The hardware configuration, operating mode, and data collection method is identical to that of most medical intravascular ultrasound (IVUS) systems. IVUS systems form images of the medium surrounding the probe based upon ultrasonic B-scans, using a straight-ray model of sound propagation. Our goal is to develop a wave-based imaging algorithm using diffraction tomography techniques. Given the hardware configuration and the imaging method, we refer to this system as ''radial reflection diffraction tomography.'' We consider two hardware configurations: a multimonostatic mode using a single transducer as described above, and a multistatic mode consisting of a single transmitter and an aperture formed by multiple receivers. In this latter case, the entire source/receiver aperture rotates about the fixed radius. Practically, such a probe is mounted at the end of a catheter or snaking tube that can be inserted into a part or medium with the goal of forming images of the plane perpendicular to the axis of rotation. We derive an analytic expression for the multimonostatic inverse but ultimately use the new Hilbert space inverse wave (HSIW) algorithm to construct images using both operating modes. Applications include improved IVUS imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts with existing access holes.

  13. Neuron-derived FGF9 is essential for scaffold formation of Bergmann radial fibers and migration of granule neurons in the cerebellum.

    PubMed

    Lin, Yongshun; Chen, Lijie; Lin, Chunhong; Luo, Yongde; Tsai, Robert Y L; Wang, Fen

    2009-05-01

    Although fibroblast growth factor 9 (FGF9) is widely expressed in the central nervous system (CNS), the function of FGF9 in neural development remains undefined. To address this question, we deleted the Fgf9 gene specifically in the neural tube and demonstrated that FGF9 plays a key role in the postnatal migration of cerebellar granule neurons. Fgf9-null mice showed severe ataxia associated with disrupted Bergmann fiber scaffold formation, impaired granule neuron migration, and upset Purkinje cell maturation. Ex vivo cultured wildtype or Fgf9-null glia displayed a stellate morphology. Coculture with wildtype neurons, but not Fgf9-deficient neurons, or treating with FGF1 or FGF9 induced the cells to adopt a radial glial morphology. In situ hybridization showed that Fgf9 was expressed in neurons and immunostaining revealed that FGF9 was broadly distributed in both neurons and Bergmann glial radial fibers. Genetic analyses revealed that the FGF9 activities in cerebellar development are primarily transduced by FGF receptors 1 and 2. Furthermore, inhibition of the MAP kinase pathway, but not the PI3K/AKT pathway, abrogated the FGF activity to induce glial morphological changes, suggesting that the activity is mediated by the MAP kinase pathway. This work demonstrates that granule neurons secrete FGF9 to control formation of the Bergmann fiber scaffold, which in turn, guides their own inward migration and maturation of Purkinje cells.

  14. Longitudinal Dispersivity in a Radial Diverging Flow Field

    NASA Astrophysics Data System (ADS)

    Seaman, J. C.; Wilson, M.; Bertsch, P. M.; Aburime, S. A.

    2005-12-01

    Hydrodynamic dispersion is an important factor controlling contaminant migration in the subsurface environment. However, few comprehensive data sets exist for evaluating the impact of travel distance and site heterogeneity on solute dispersion under non-uniform flow conditions. In addition, anionic tracers are often used to estimate physical transport parameters based on an erroneous assumption of conservative (i.e., non-reactive) behavior. Therefore, a series of field experiments using tritiated water and several other commonly used hydrologic tracers (Br, Cl, FBAs) were conducted in the water-table aquifer on the U.S. Department of Energy's Savannah River Site (Aiken, SC) to evaluate solute transport processes in a diverging radial flow field. For each experiment, tracer-free groundwater was injected for approximately 24 hours at a fixed rate of 56.7 L/min (15 gpm) to establish a forced radial gradient prior to the introduction of a tracer pulse. After the tracer pulse, the forced gradient was maintained throughout the experiment using non-labeled groundwater. Tracer migration was monitored using a set of six sampling wells radially spaced at approximate distances of 1.5, 3, and 4.5 meters from a central injection well. Each sampling well was further divided into three discrete sampling depths that were monitored continuously throughout the course of the tracer experiment. At various time intervals, discrete groundwater samples were collected from all 18 sampling ports for tritium analysis. Longitudinal dispersivity for tritium breakthrough at each sampling location was estimated using analytical approximations of the convection dispersion equation (CDE) for radial flow assuming an instantaneous Dirac pulse and a pulse of known duration. The results were also compared to dispersivity values derived from fitting the tracer data to analytical solutions derived from assuming uniform flow conditions. Tremendous variation in dispersivity values and tracer arrival

  15. Method to derive restoring forces of strained molecules from kinetic measurements.

    PubMed

    Huang, Zhen; Yang, Qing-Zheng; Khvostichenko, Daria; Kucharski, Timothy J; Chen, Joseph; Boulatov, Roman

    2009-02-04

    We report a method to estimate the restoring force of a constrained small molecule and relate changes in its reactivity to this force. Restoring force is a size-invariant measure of molecular strain and offers a conceptual framework to bridge studies of macromolecular reactions by force spectroscopies with those of strained small molecules. We illustrate our method by showing that E stiff stilbene (1,1'-Delta-biindan) with up to 700 pN of force along its C6,C6' axis is accessible by photoisomerization. It reverts thermally to the Z isomer with tau(1/2) approximately 100 ms, probably long enough to be useful for microscale actuation. The quantum yield of photoisomerization and the activation barrier of thermal isomerization of constrained stiff stilbene increase sharply as the restoring force decreases.

  16. Formulas for Radial Transport in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Desch, Steven J.; Estrada, Paul R.; Kalyaan, Anusha; Cuzzi, Jeffrey N.

    2017-05-01

    The quantification of the radial transport of gaseous species and solid particles is important to many applications in protoplanetary disk evolution. An especially important example is determining the location of the water snow lines in a disk, which requires computing the rates of outward radial diffusion of water vapor and the inward radial drift of icy particles; however, the application is generalized to evaporation fronts of all volatiles. We review the relevant formulas using a uniform formalism. This uniform treatment is necessary because the literature currently contains at least six mutually exclusive treatments of radial diffusion of gas, only one of which is correct. We derive the radial diffusion equations from first principles using Fick's law. For completeness, we also present the equations for radial transport of particles. These equations may be applied to studies of diffusion of gases and particles in protoplanetary and other accretion disks.

  17. Radial Artery Catheterization

    MedlinePlus

    ... of the radial artery for cardiac catheterization procedures. Advantages of Radial Artery Catheterization Any catheter placement into ... walk, and eat immediately. This is a particular advantage for patients with back problems because there is ...

  18. Comparison of cloud forcing derived from the Earth Radiation Budget Experiment with that simulated by the NCAR Community Climate Model

    NASA Technical Reports Server (NTRS)

    Kiehl, J. T.; Ramanathan, V.

    1990-01-01

    The cloud radiative forcing derived from the Earth Radiation Budget Experiment (ERBE) data was compared with cloud forcing simulated by a T42 version of the NCAR Community Climate Model (CCM). The comparison indicates a number of deficiencies in the CCM. Namely, it is shown that the model emits substantially more long-wave radiation than is observed by ERBE. This overestimation is attributed to two model characteristics: (1) the model is too dry and thus reduces the greenhouse longwave radiation effect of the atmosphere (permitting more longwave radiation to escape into space); and (2) the effective high cloud amount is quite small in the model.

  19. Field Sampling and Modeling of Creosote-Derived Contamination in a Tdally Forced Aquifer

    NASA Astrophysics Data System (ADS)

    Bishop, C.

    2003-12-01

    We are investigating the fate and transport of a creosote-derived groundwater contaminant plume found in an aquifer adjacent to and beneath a large, tidally forced river. The site, located in Coquitlam, BC, is adjacent to the Fraser River, and has been an active wood preserving facility since the 1920's. In the on-shore source zone, creosote has penetrated into the aquifer and a dissolved-phase plume, composed primarily of naphthalene, flows in the site aquifer from the source zone towards and below the river, eventually discharging from the river bottom. A capture well has been operated since 1996 to contain and capture the contaminant source. Previous research at this site has documented that biodegradation of naphthalene takes place in the plume fringe in the region of the aquifer that is beneath the river, but not onshore. Abundant methane and ferrous iron in the aquifer suggests that iron reduction and methanogenesis are the dominant terminal electron accepting processes. High offshore naphthalene concentrations sampled in 1999 despite three years of source containment and degradation led to the hypothesis that the plume may be at steady state due to buffering of contaminant concentrations by desorption from aquifer sediments. Naphthalene concentrations sampled in this study show that the contaminant plume is not at steady state. Results of groundwater flow modelling and sorption data show that the continued presence of high concentrations of naphthalene offshore are likely due to incomplete source containment or to slow migration of contaminants from upgradient regions of the aqueous plume. Although naphthalene has been the focus of all previous investigations of the offshore plume at this site, recent sampling shows that two other components of creosote, indane and benzothiophene, become the dominant components of the aqueous phase plume as it approaches the discharge point. Significant concentrations of these contaminants are likely discharging to the river

  20. Complex force history of a calving-generated glacial earthquake derived from broadband seismic inversion

    NASA Astrophysics Data System (ADS)

    Sergeant, Amandine; Mangeney, Anne; Stutzmann, Eléonore; Montagner, Jean-Paul; Walter, Fabian; Moretti, Laurent; Castelnau, Olivier

    2016-02-01

    The force applied to the Earth by the calving of two icebergs at Jakobshavn Isbrae, Greenland, has been quantified. The source force history was recovered by inversion of regional broadband seismograms without any a priori constraint on the source time function, in contrast with previous studies. For periods 10-100 s, the three-component force can be obtained from distant stations alone and is proportional to the closest station seismograms. This inversion makes it possible to quantify changes of the source force direction and amplitude as a function of time and frequency. A detailed comparison with a video of the event was used to identify four forces associated with collision, then bottom-out and top-out rotation of the first and second icebergs, and ice mélange motion. Only the two iceberg rotations were identified in previous studies. All four processes are found here to contribute to the force amplitude and variability. Such a complete time-frequency force history provides unique dynamical constraints for mechanical calving models.

  1. Integrated Analysis of Contractile Kinetics, Force Generation, and Electrical Activity in Single Human Stem Cell-Derived Cardiomyocytes.

    PubMed

    Kijlstra, Jan David; Hu, Dongjian; Mittal, Nikhil; Kausel, Eduardo; van der Meer, Peter; Garakani, Arman; Domian, Ibrahim J

    2015-12-08

    The quantitative analysis of cardiomyocyte function is essential for stem cell-based approaches for the in vitro study of human cardiac physiology and pathophysiology. We present a method to comprehensively assess the function of single human pluripotent stem cell-derived cardiomyocyte (hPSC-CMs) through simultaneous quantitative analysis of contraction kinetics, force generation, and electrical activity. We demonstrate that statistical analysis of movies of contracting hPSC-CMs can be used to quantify changes in cellular morphology over time and compute contractile kinetics. Using a biomechanical model that incorporates substrate stiffness, we calculate cardiomyocyte force generation at single-cell resolution and validate this approach with conventional traction force microscopy. The addition of fluorescent calcium indicators or membrane potential dyes allows the simultaneous analysis of contractility and calcium handling or action potential morphology. Accordingly, our approach has the potential for broad application in the study of cardiac disease, drug discovery, and cardiotoxicity screening.

  2. Integrated Analysis of Contractile Kinetics, Force Generation, and Electrical Activity in Single Human Stem Cell-Derived Cardiomyocytes

    PubMed Central

    Kijlstra, Jan David; Hu, Dongjian; Mittal, Nikhil; Kausel, Eduardo; van der Meer, Peter; Garakani, Arman; Domian, Ibrahim J.

    2015-01-01

    Summary The quantitative analysis of cardiomyocyte function is essential for stem cell-based approaches for the in vitro study of human cardiac physiology and pathophysiology. We present a method to comprehensively assess the function of single human pluripotent stem cell-derived cardiomyocyte (hPSC-CMs) through simultaneous quantitative analysis of contraction kinetics, force generation, and electrical activity. We demonstrate that statistical analysis of movies of contracting hPSC-CMs can be used to quantify changes in cellular morphology over time and compute contractile kinetics. Using a biomechanical model that incorporates substrate stiffness, we calculate cardiomyocyte force generation at single-cell resolution and validate this approach with conventional traction force microscopy. The addition of fluorescent calcium indicators or membrane potential dyes allows the simultaneous analysis of contractility and calcium handling or action potential morphology. Accordingly, our approach has the potential for broad application in the study of cardiac disease, drug discovery, and cardiotoxicity screening. PMID:26626178

  3. Ab initio calculations on peptide-derived oxazoles and thiazoles: Improved molecular mechanics parameters for the AMBER* force field

    NASA Astrophysics Data System (ADS)

    Boden, Christopher D. J.; Pattenden, Gerald

    1999-03-01

    Ab initio calculations at the RHF/6-31G* and MP2/6- 31G*//RHF/6-31G* levels of theory are performed for 2-methyl-4-carboxamido-oxazoles and -thiazoles, including rotational profiles for the ring-carboxamide bond, which showed the expected conjugation and hydrogen bonding effects. On the basis of these data, newly optimised stretch, bend and torsional parameters for the AMBER* force field are derived, along with CHELPG-fitted partial atomic charges.

  4. Deriving the Work Done by an Inverse Square Force in Non-Calculus-Based Introductory Physics Courses

    ERIC Educational Resources Information Center

    Hu, Ben Yu-Kuang

    2012-01-01

    I describe a method of evaluating the integral of 1/r[superscript 2] with respect to r that uses only algebra and the concept of area underneath a curve, and which does not formally employ any calculus. This is useful for algebra-based introductory physics classes (where the use of calculus is forbidden) to derive the work done by the force of one…

  5. Numerical modeling of the Mount Meager landslide constrained by its force history derived from seismic data

    NASA Astrophysics Data System (ADS)

    Moretti, L.; Allstadt, K.; Mangeney, A.; Capdeville, Y.; Stutzmann, E.; Bouchut, F.

    2015-04-01

    We focus on the 6 August 2010 Mount Meager landslide that occurred in Southwest British Columbia, Canada. This 48.5 Mm3 rockslide that rapidly changed into a debris flow was recorded by over 25 broadband seismic stations. We showed that the waveform inversion of the seismic signal making it possible to calculate the time history of the force applied by the landslide to the ground is very robust and stable, even when using only data from a single station. By comparing this force with the force calculated through numerical modeling of the landslide, we are able to support the interpretation of seismic data made using a simple block model. However, our study gives different values of the friction coefficients involved and more details about the volumes and orientation of the subevents and the flow trajectory and velocity. Our sensitivity analysis shows that the characteristics of the released mass and the friction coefficients all contribute to the amplitude and the phase of the force. Despite this complexity, our study makes it possible to discriminate the best values of all these parameters. Our results suggest that comparing simulated and inverted forces helps to identify appropriate rheological laws for natural flows. We also show that except for the initial collapse, peaks in the low-frequency force related to bends and runup over topography changes are associated with high-frequency generation, possibly due to an increased agitation of the granular material involved.

  6. Biomechanical force induces the growth factor production in human periodontal ligament-derived cells.

    PubMed

    Ichioka, Hiroaki; Yamamoto, Toshiro; Yamamoto, Kenta; Honjo, Ken-Ichi; Adachi, Tetsuya; Oseko, Fumishige; Mazda, Osam; Kanamura, Narisato; Kita, Masakazu

    2016-01-01

    Although many reports have been published on the functional roles of periodontal ligament (PDL) cells, the mechanisms involved in the maintenance and homeostasis of PDL have not been determined. We investigated the effects of biomechanical force on growth factor production, phosphorylation of MAPKs, and intracellular transduction pathways for growth factor production in human periodontal ligament (hPDL) cells using MAPK inhibitors. hPDL cells were exposed to mechanical force (6 MPa) using a hydrostatic pressure apparatus. The levels of growth factor mRNA and protein were examined by real-time RT-PCR and ELISA. The phosphorylation of MAPKs was measured using BD™ CBA Flex Set. In addition, MAPKs inhibitors were used to identify specific signal transduction pathways. Application of biomechanical force (equivalent to occlusal force) increased the synthesis of VEGF-A, FGF-2, and NGF. The application of biomechanical force increased the expression levels of phosphorylated ERK and p38, but not of JNK. Furthermore, the levels of VEGF-A and NGF expression were suppressed by ERK or p38 inhibitor. The growth factors induced by biomechanical force may play a role in the mechanisms of homeostasis of PDL.

  7. CHARMM additive all-atom force field for carbohydrate derivatives and its utility in polysaccharide and carbohydrate-protein modeling.

    PubMed

    Guvench, Olgun; Mallajosyula, Sairam S; Raman, E Prabhu; Hatcher, Elizabeth; Vanommeslaeghe, Kenno; Foster, Theresa J; Jamison, Francis W; Mackerell, Alexander D

    2011-10-11

    Monosaccharide derivatives such as xylose, fucose, N-acetylglucosamine (GlcNAc), N-acetylgalactosamine (GlaNAc), glucuronic acid, iduronic acid, and N-acetylneuraminic acid (Neu5Ac) are important components of eukaryotic glycans. The present work details development of force-field parameters for these monosaccharides and their covalent connections to proteins via O-linkages to serine or threonine sidechains and via N-linkages to asparagine sidechains. The force field development protocol was designed to explicitly yield parameters that are compatible with the existing CHARMM additive force field for proteins, nucleic acids, lipids, carbohydrates, and small molecules. Therefore, when combined with previously developed parameters for pyranose and furanose monosaccharides, for glycosidic linkages between monosaccharides, and for proteins, the present set of parameters enables the molecular simulation of a wide variety of biologically-important molecules such as complex carbohydrates and glycoproteins. Parametrization included fitting to quantum mechanical (QM) geometries and conformational energies of model compounds, as well as to QM pair interaction energies and distances of model compounds with water. Parameters were validated in the context of crystals of relevant monosaccharides, as well NMR and/or x-ray crystallographic data on larger systems including oligomeric hyaluronan, sialyl Lewis X, O- and N-linked glycopeptides, and a lectin:sucrose complex. As the validated parameters are an extension of the CHARMM all-atom additive biomolecular force field, they further broaden the types of heterogeneous systems accessible with a consistently-developed force-field model.

  8. Force and scleraxis synergistically promote the commitment of human ES cells derived MSCs to tenocytes

    PubMed Central

    Chen, Xiao; Yin, Zi; Chen, Jia-lin; Shen, Wei-liang; Liu, Huan-huan; Tang, Qiao-mei; Fang, Zhi; Lu, Lin-rong; Ji, Junfeng; Ouyang, Hong-wei

    2012-01-01

    As tendon stem/progenitor cells were reported to be rare in tendon tissues, tendons as vulnerable targets of sports injury possess poor self-repair capability. Human ESCs (hESCs) represent a promising approach to tendon regeneration. But their teno-lineage differentiation strategy has yet to be defined. Here, we report that force combined with the tendon-specific transcription factor scleraxis synergistically promoted commitment of hESCs to tenocyte for functional tissue regeneration. Force and scleraxis can independently induce tendon differentiation. However, force alone concomitantly activated osteogenesis, while scleraxis alone was not sufficient to commit, but augment tendon differentiation. Scleraxis synergistically augmented the efficacy of force on teno-lineage differentiation and inhibited the osteo-lineage differentiation by antagonized BMP signaling cascade. The findings not only demonstrated a novel strategy of directing hESC differentiation to tenocyte for functional tendon regeneration, but also offered insights into understanding the network of force, scleraxis and bmp2 controlling tendon-lineage differentiation. PMID:23243495

  9. SNARE-mediated membrane fusion trajectories derived from force-clamp experiments.

    PubMed

    Oelkers, Marieelen; Witt, Hannes; Halder, Partho; Jahn, Reinhard; Janshoff, Andreas

    2016-11-15

    Fusion of lipid bilayers is usually prevented by large energy barriers arising from removal of the hydration shell, formation of highly curved structures, and, eventually, fusion pore widening. Here, we measured the force-dependent lifetime of fusion intermediates using membrane-coated silica spheres attached to cantilevers of an atomic-force microscope. Analysis of time traces obtained from force-clamp experiments allowed us to unequivocally assign steps in deflection of the cantilever to membrane states during the SNARE-mediated fusion with solid-supported lipid bilayers. Force-dependent lifetime distributions of the various intermediate fusion states allowed us to propose the likelihood of different fusion pathways and to assess the main free energy barrier, which was found to be related to passing of the hydration barrier and splaying of lipids to eventually enter either the fully fused state or a long-lived hemifusion intermediate. The results were compared with SNARE mutants that arrest adjacent bilayers in the docked state and membranes in the absence of SNAREs but presence of PEG or calcium. Only with the WT SNARE construct was appreciable merging of both bilayers observed.

  10. SNARE-mediated membrane fusion trajectories derived from force-clamp experiments

    PubMed Central

    Oelkers, Marieelen; Witt, Hannes; Halder, Partho; Janshoff, Andreas

    2016-01-01

    Fusion of lipid bilayers is usually prevented by large energy barriers arising from removal of the hydration shell, formation of highly curved structures, and, eventually, fusion pore widening. Here, we measured the force-dependent lifetime of fusion intermediates using membrane-coated silica spheres attached to cantilevers of an atomic-force microscope. Analysis of time traces obtained from force-clamp experiments allowed us to unequivocally assign steps in deflection of the cantilever to membrane states during the SNARE-mediated fusion with solid-supported lipid bilayers. Force-dependent lifetime distributions of the various intermediate fusion states allowed us to propose the likelihood of different fusion pathways and to assess the main free energy barrier, which was found to be related to passing of the hydration barrier and splaying of lipids to eventually enter either the fully fused state or a long-lived hemifusion intermediate. The results were compared with SNARE mutants that arrest adjacent bilayers in the docked state and membranes in the absence of SNAREs but presence of PEG or calcium. Only with the WT SNARE construct was appreciable merging of both bilayers observed. PMID:27807132

  11. Entropic forces in Brownian motion

    NASA Astrophysics Data System (ADS)

    Roos, Nico

    2014-12-01

    Interest in the concept of entropic forces has risen considerably since Verlinde proposed in 2011 to interpret the force in Newton's second law and gravity as entropic forces. Brownian motion—the motion of a small particle (pollen) driven by random impulses from the surrounding molecules—may be the first example of a stochastic process in which such forces are expected to emerge. In this article, it is shown that at least two types of entropic force can be identified in three-dimensional Brownian motion. This analysis yields simple derivations of known results of Brownian motion, Hooke's law, and—applying an external (non-radial) force—Curie's law and the Langevin-Debye equation.

  12. Derivation of revised formulae for eddy viscous forces used in the ocean general circulation model

    NASA Technical Reports Server (NTRS)

    Chou, Ru Ling

    1988-01-01

    Presented is a re-derivation of the eddy viscous dissipation tensor commonly used in present oceanographic general circulation models. When isotropy is imposed, the currently-used form of the tensor fails to return to the laplacian operator. In this paper, the source of this error is identified in a consistent derivation of the tensor in both rectangular and earth spherical coordinates, and the correct form of the eddy viscous tensor is presented.

  13. Global Aerosol Radiative Forcing Derived from Sea WiFS-Inferred Aerosol Optical Properties

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Chan, Pui-King; Wang, Menghua

    1999-01-01

    Aerosol optical properties inferred from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) radiance measurements are used to compute the aerosol shortwave radiative forcing using a radiative transfer model. The aerosol optical thickness at the wavelength of 865-nm is taken from the SeaWIFS archive. It is found that the nominal optical thickness over oceans ranges from 0.1 to 0.2. Using a maritime aerosol model and the radiances measured at the various SeaWiFS channels, the Angstrom exponent is determined to be 0.2174, the single-scattering albedo to be 0.995, and the asymmetry factor to be 0.786. The radiative transfer model has eight bands in the visible and ultraviolet spectral regions and three bands in the near infrared. It includes the absorption due to aerosols, water vapor, carbon dioxide, and oxygen, and the scattering due to aerosols and gases (Rayleigh scattering). The radiative forcing is computed over global oceans for four months (January, April, July, and October, 1998) to represent four seasons. It is found that the aerosol radiative forcing is large and changes significantly with seasons near the continents with large-scale forest fires and desert dust. Averaged over oceans and the four months, the aerosol radiative forcing is approximately 7 W/sq m at the top of the atmosphere. This large radiative forcing is expected to have a significant cooling effect on the Earth's climate as implied from simulations of a number of general circulation models.

  14. Global Aerosol Radiative Forcing Derived from Sea WiFS-Inferred Aerosol Optical Properties

    NASA Technical Reports Server (NTRS)

    Chou, Ming-Dah; Chan, Pui-King; Wang, Menghua

    1999-01-01

    Aerosol optical properties inferred from the Sea-viewing Wide Field-of-view Sensor (SeaWiFS) radiance measurements are used to compute the aerosol shortwave radiative forcing using a radiative transfer model. The aerosol optical thickness at the wavelength of 865-nm is taken from the SeaWIFS archive. It is found that the nominal optical thickness over oceans ranges from 0.1 to 0.2. Using a maritime aerosol model and the radiances measured at the various SeaWiFS channels, the Angstrom exponent is determined to be 0.2174, the single-scattering albedo to be 0.995, and the asymmetry factor to be 0.786. The radiative transfer model has eight bands in the visible and ultraviolet spectral regions and three bands in the near infrared. It includes the absorption due to aerosols, water vapor, carbon dioxide, and oxygen, and the scattering due to aerosols and gases (Rayleigh scattering). The radiative forcing is computed over global oceans for four months (January, April, July, and October, 1998) to represent four seasons. It is found that the aerosol radiative forcing is large and changes significantly with seasons near the continents with large-scale forest fires and desert dust. Averaged over oceans and the four months, the aerosol radiative forcing is approximately 7 W/sq m at the top of the atmosphere. This large radiative forcing is expected to have a significant cooling effect on the Earth's climate as implied from simulations of a number of general circulation models.

  15. A fully relativistic radial fall

    NASA Astrophysics Data System (ADS)

    Spallicci, Alessandro D. A. M.; Ritter, Patxi

    2014-10-01

    Radial fall has historically played a momentous role. It is one of the most classical problems, the solutions of which represent the level of understanding of gravitation in a given epoch. A gedankenexperiment in a modern frame is given by a small body, like a compact star or a solar mass black hole, captured by a supermassive black hole. The mass of the small body itself and the emission of gravitational radiation cause the departure from the geodesic path due to the back-action, that is the self-force. For radial fall, as any other non-adiabatic motion, the instantaneous identity of the radiated energy and the loss of orbital energy cannot be imposed and provide the perturbed trajectory. In the first part of this paper, we present the effects due to the self-force computed on the geodesic trajectory in the background field. Compared to the latter trajectory, in the Regge-Wheeler, harmonic and all others smoothly related gauges, a far observer concludes that the self-force pushes inward (not outward) the falling body, with a strength proportional to the mass of the small body for a given large mass; further, the same observer notes a higher value of the maximal coordinate velocity, this value being reached earlier during infall. In the second part of this paper, we implement a self-consistent approach for which the trajectory is iteratively corrected by the self-force, this time computed on osculating geodesics. Finally, we compare the motion driven by the self-force without and with self-consistent orbital evolution. Subtle differences are noticeable, even if self-force effects have hardly the time to accumulate in such a short orbit.

  16. Radial arm strike rail

    DOEpatents

    McKeown, Mark H.; Beason, Steven C.

    1991-01-01

    The radial arm strike rail assembly is a system for measurement of bearings, directions, and stereophotography for geologic mapping, particularly where magnetic compasses are not appropriate. The radial arm, pivoting around a shaft axis, provides a reference direction determination for geologic mapping and bearing or direction determination. The centerable and levelable pedestal provide a base for the radial arm strike rail and the telescoping camera pedestal. The telescoping feature of the radial arm strike rail allows positioning the end of the rail for strike direction or bearing measurement with a goniometer.

  17. Novel Integration Radial and Axial Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Blumenstock, Kenneth; Brown, Gary

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics; separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and magnetic field modeling results will be presented.

  18. Novel Integrated Radial and Axial Magnetic Bearing

    NASA Technical Reports Server (NTRS)

    Blumenstock, Kenneth A.; Brown, Gary L.; Powers, Edward I. (Technical Monitor)

    2000-01-01

    Typically, fully active magnetically suspended systems require one axial and two radial magnetic bearings. Combining radial and axial functions into a single device allows for more compact and elegant packaging. Furthermore, in the case of high-speed devices such as energy storage flywheels, it is beneficial to minimize shaft length to keep rotor mode frequencies as high as possible. Attempts have been made to combine radial and axial functionality, but with certain drawbacks. One approach requires magnetic control flux to flow through a bias magnet reducing control effectiveness, thus resulting in increased resistive losses. This approach also requires axial force producing magnetic flux to flow in a direction into the rotor laminate that is undesirable for minimizing eddy-current losses resulting in rotational losses. Another approach applies a conical rotor shape to what otherwise would be a radial heteropolar magnetic bearing configuration. However, positional non-linear effects are introduced with this scheme and the same windings are used for bias, radial, and axial control adding complexity to the controller and electronics. For this approach, the amount of axial capability must be limited. It would be desirable for an integrated radial and axial magnetic bearing to have the following characteristics, separate inputs for radial and axial control for electronics and control simplicity, all magnetic control fluxes should only flow through their respective air gaps and should not flow through any bias magnets for minimal resistive losses, be of a homopolar design to minimize rotational losses, position related non-linear effects should be minimized, and dependent upon the design parameters, be able to achieve any radial/axial force or power ratio as desired. The integrated radial and axial magnetic bearing described in this paper exhibits all these characteristics. Magnetic circuit design, design equations, and analysis results will be presented.

  19. A comparison of catch phase force-time characteristics during clean derivatives from the knee.

    PubMed

    Comfort, Paul; Williams, Robert; Suchomel, Timothy J; Lake, Jason P

    2016-09-27

    The aim of this study was to compare load-absorption force-time characteristics of the clean from the knee (CK), power clean from the knee (PCK) and clean pull from the knee (CPK). Ten collegiate athletes (age 27.5 ± 4.2 years; height 180.4 ± 6.7 cm; mass 84.4 ± 7.8 kg), performed three repetitions each of the CK, PCK and CPK with 90% of their 1RM power clean on a force platform. The CK load-absorption duration (0.95 ± 0.35 s) was significantly longer compared to the CPK (0.44 ± 0.15 s; p < 0.001, d = 2.53), but not compared to the PCK (0.56 ± 0.11 s; p > 0.05, d = 1.08), with no differences between PCK and CPK (p > 0.05, d = 0.91). The CPK demonstrated the greatest mean force (2039 ± 394 N), which was significantly greater than the PCK (1771 ± 325 N; p = 0.012, d = 0.83), but not significantly different to the CK (1830 ± 331 N; p > 0.05, d = 0.60); CK and PCK were not different (p > 0.05, d = 0.18). Significantly more load-absorption work was performed during the CK (655 ± 276 J) compared to the PCK (288 ± 109 J; d = 1.75, p < 0.001); but not compared to the CPK (518 ± 132 J; d = 0.80, p > 0.05). Additionally, more load-absorption work was performed during the CPK compared to the PCK (d = 1.90, p = 0.032). Inclusion of the catch phase during the CK does not provide any additional stimulus in terms of mean force or work during the load-absorption phase compared to the CPK, while the CPK may be beneficial in training rapid force absorption due to high force and a short duration.

  20. Study on the radial composite piezoelectric ceramic transducer in radial vibration.

    PubMed

    Lin, Shuyu

    2007-03-01

    A new type of radial composite piezoelectric transducer in radial vibration is developed and analyzed. The radial composite transducer consists of a piezoelectric ceramic thin ring polarized in the thickness direction and a metal thin circular ring. They are connected together and excited to vibrate in the radial direction. The radial vibrations of a piezoelectric ceramic thin ring and a metal thin circular ring are analyzed, respectively. Their radial electro-mechanical equivalent circuits are obtained. Based on the electro-mechanical equivalent circuits and using the boundary conditions between the piezoelectric ceramic thin ring and the metal thin circular ring in the radial direction, the electro-mechanical equivalent circuit of the radial composite piezoelectric transducer is derived out and the resonance frequency equation is obtained. The relationship between the resonance frequency and the geometrical dimensions of the transducer is analyzed. Some radial composite piezoelectric transducers are designed and manufactured. The resonance frequencies and the anti-resonance frequencies, the electro-mechanical equivalent circuit parameters are measured. The effective electro-mechanical coupling coefficient and the mechanical quality factor are calculated. It is illustrated that the measured radial resonance frequencies are in good agreement with the theoretical results from the resonance frequency equation.

  1. Roll Damping Derivatives from Generalized Lifting-Surface Theory and Wind Tunnel Forced-Oscillation Tests

    NASA Technical Reports Server (NTRS)

    Pototzky, Anthony S; Murphy, Patrick C.

    2014-01-01

    Improving aerodynamic models for adverse loss-of-control conditions in flight is an area being researched under the NASA Aviation Safety Program. Aerodynamic models appropriate for loss of control conditions require a more general mathematical representation to predict nonlinear unsteady behaviors. As more general aerodynamic models are studied that include nonlinear higher order effects, the possibility of measurements that confound aerodynamic and structural responses are probable. In this study an initial step is taken to look at including structural flexibility in analysis of rigid-body forced-oscillation testing that accounts for dynamic rig, sting and balance flexibility. Because of the significant testing required and associated costs in a general study, it makes sense to capitalize on low cost analytical methods where possible, especially where structural flexibility can be accounted for by a low cost method. This paper provides an initial look at using linear lifting surface theory applied to rigid-body aircraft roll forced-oscillation tests.

  2. Seasonal cloud-radiative forcing over land and ocean derived from ERBE satellites

    NASA Technical Reports Server (NTRS)

    Harrison, Edwin F.; Gibson, Gary G.

    1991-01-01

    Earth Radiation Budget Experiment (ERBE) data are analyzed to determine seasonal variations of radiative parameters. Particular attention is given to annual variations of the top-of-the atmosphere zonally averaged outgoing long-wave (LW) and absorbed short-wave (SW) flux, as well as the short- and long-wave components of cloud-radiative forcing. The ERBE results reveal significant seasonal variations in both outgoing LW and absorbed SW flux, and a pronounced difference between oceanic and continental surfaces.

  3. Management Impact Assessment of Refuse-Derived Fuel Implementation at Wright-Patterson Air Force Base.

    DTIC Science & Technology

    1982-03-19

    Richard K. McIntosh 9. PERFORMING ORGANIZATION NAME AND ADDRESS 10. PROGRAM ELEMENT PROJECT. TASK ULTRASYSTEMS, INC. AREA & WORK UNIT NUMBERS 10340...Democracy Lane Program Element : 64708F Fairfax, Virginia 22030 JON: 20545017 I. CONTROLLING OFFICE NAME AND ADDRESS 12. REPORT DATE Air Force Engineering...having reviewed the RDF project at WPAFB and interviewed people in all of the involved organizational elements and functional areas within those

  4. Analysis of Dynamic Stability of Space Launch Vehicles under Aerodynamic Forces Using CFD Derived Data

    NASA Astrophysics Data System (ADS)

    Trikha, M.; Gopalakrishnan, S.; Mahapatra, D. Roy

    2011-09-01

    A computational framework is developed to investigate the dynamic stability of space launch vehicles subjected to aerodynamic forces. A detailed mechanics based mathematical model of a moving flexible vehicle is used. The aerodynamic forces on the vehicle are obtained from simulation using Computational Fluid Dynamics (CFD) package. The objective behind this investigation is to analyze the problem of aeroelastic instability in blunt/conical nose slender space launch vehicles. Coupling among the rigid-body modes, the longitudinal vibration modes, and the transverse vibrational modes are considered. The effect of propulsive thrust as a follower force is also considered. A one-dimensional finite element model is developed to investigate the occurrence of aeroelastic instabilities of various types. Eigenvalues of the vehicle are determined in order to analyze the stable regimes. As a special case, we show numerical simulations by considering a typical vehicle configuration, for a vehicle Mach number of 0.8. Phenomenon of flutter is observed at this Mach number. The proposed analysis is suitable for different launch events such as vehicle take-off, maximum dynamic pressure regime, thrust transients, stage separation etc. The approach developed in this paper can be utilized for preliminary design of launch vehicles and establishing the stability boundaries for different trajectory parameters.

  5. First order derivative spectrophotometric method for the determination of benidipine hydrochloride pharmaceutical preparations and forced degradation study

    NASA Astrophysics Data System (ADS)

    Karasaka, Ayça

    2015-06-01

    A simple and rapid first order derivative spectrophotometric method was developed for the determination of benidipine hydrochloride in pure form and pharmaceutical preparations. For the first derivative spectrophotometric method, the distances between two extremum values l (peak-to-peak amplitudes), 230.2/241.5 nm. The proposed method was validated according to the ICH guidelines with respect to linearity, limit of detection, limit of quantification, accuracy, precision (intra- and inter-day) and recovery were evaluated. The linearity of the method was in the range of 0.2-2.0 μg/mL. Limits of detection and quantification were 0.58 and 1.73 μg/mL, respectively. The proposed method was successfully applied to the analysis of pharmaceutical preparations. In addition, forced degradation studies were performed on the benidipine hydrochloride drag substance. The drug substance was exposed to the stress conditions of hydrolysis (acid and base).

  6. Simulations of cloud-radiation interaction using large-scale forcing derived from the CINDY/DYNAMO northern sounding array

    SciTech Connect

    Wang, Shuguang; Sobel, Adam H.; Fridlind, Ann; Feng, Zhe; Comstock, Jennifer M.; Minnis, Patrick; Nordeen, Michele L.

    2015-09-25

    The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large scale forcing dataset derived from the DYNAMO northern sounding array observations, and carried out in a doubly-periodic domain using the Weather Research and Forecasting (WRF) model. simulated cloud properties and radiative fluxes are compared to those derived from the S-Polka radar and satellite observations. Furthermore, to accommodate the uncertainty in simulated cloud microphysics, a number of single moment (1M) and double moment (2M) microphysical schemes in the WRF model are tested.

  7. Simulations of cloud-radiation interaction using large-scale forcing derived from the CINDY/DYNAMO northern sounding array

    DOE PAGES

    Wang, Shuguang; Sobel, Adam H.; Fridlind, Ann; ...

    2015-09-25

    The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large scale forcing dataset derived from the DYNAMO northern sounding array observations, and carried out in a doubly-periodic domain using the Weather Research and Forecasting (WRF) model. simulatedmore » cloud properties and radiative fluxes are compared to those derived from the S-Polka radar and satellite observations. Furthermore, to accommodate the uncertainty in simulated cloud microphysics, a number of single moment (1M) and double moment (2M) microphysical schemes in the WRF model are tested.« less

  8. Triple acting radial seal

    DOEpatents

    Ebert, Todd A [West Palm Beach, FL; Carella, John A [Jupiter, FL

    2012-03-13

    A triple acting radial seal used as an interstage seal assembly in a gas turbine engine, where the seal assembly includes an interstage seal support extending from a stationary inner shroud of a vane ring, the interstage seal support includes a larger annular radial inward facing groove in which an outer annular floating seal assembly is secured for radial displacement, and the outer annular floating seal assembly includes a smaller annular radial inward facing groove in which an inner annular floating seal assembly is secured also for radial displacement. A compliant seal is secured to the inner annular floating seal assembly. The outer annular floating seal assembly encapsulates the inner annular floating seal assembly which is made from a very low alpha material in order to reduce thermal stress.

  9. Searching for Radial Symmetry.

    PubMed

    Jennings, Ben J; Kingdom, Frederick A A

    2017-01-01

    Symmetry is ubiquitous in the natural world. Numerous investigations, dating back over one hundred years, have explored the visual processing of symmetry. However, these studies have been concerned with mirror symmetry, overlooking radial (or rotational) symmetry, which is also prevalent in nature. Using a visual search paradigm, which approximates the everyday task of searching for an object embedded in background clutter, we have measured how quickly and how accurately human observers detect radially symmetric dot patterns. Performance was compared with mirror symmetry. We found that with orders of radial symmetry greater than 5, radial symmetry can be detected more easily than mirror symmetry, revealing for the first time that radial symmetry is a salient property of objects for human vision.

  10. Searching for Radial Symmetry

    PubMed Central

    Kingdom, Frederick A. A.

    2017-01-01

    Symmetry is ubiquitous in the natural world. Numerous investigations, dating back over one hundred years, have explored the visual processing of symmetry. However, these studies have been concerned with mirror symmetry, overlooking radial (or rotational) symmetry, which is also prevalent in nature. Using a visual search paradigm, which approximates the everyday task of searching for an object embedded in background clutter, we have measured how quickly and how accurately human observers detect radially symmetric dot patterns. Performance was compared with mirror symmetry. We found that with orders of radial symmetry greater than 5, radial symmetry can be detected more easily than mirror symmetry, revealing for the first time that radial symmetry is a salient property of objects for human vision. PMID:28855979

  11. Surface force measurements and simulations of mussel-derived peptide adhesives on wet organic surfaces

    PubMed Central

    Levine, Zachary A.; Rapp, Michael V.; Wei, Wei; Mullen, Ryan Gotchy; Wu, Chun; Zerze, Gül H.; Mittal, Jeetain; Waite, J. Herbert; Israelachvili, Jacob N.; Shea, Joan-Emma

    2016-01-01

    Translating sticky biological molecules—such as mussel foot proteins (MFPs)—into synthetic, cost-effective underwater adhesives with adjustable nano- and macroscale characteristics requires an intimate understanding of the glue’s molecular interactions. To help facilitate the next generation of aqueous adhesives, we performed a combination of surface forces apparatus (SFA) measurements and replica-exchange molecular dynamics (REMD) simulations on a synthetic, easy to prepare, Dopa-containing peptide (MFP-3s peptide), which adheres to organic surfaces just as effectively as its wild-type protein analog. Experiments and simulations both show significant differences in peptide adsorption on CH3-terminated (hydrophobic) and OH-terminated (hydrophilic) self-assembled monolayers (SAMs), where adsorption is strongest on hydrophobic SAMs because of orientationally specific interactions with Dopa. Additional umbrella-sampling simulations yield free-energy profiles that quantitatively agree with SFA measurements and are used to extract the adhesive properties of individual amino acids within the context of MFP-3s peptide adhesion, revealing a delicate balance between van der Waals, hydrophobic, and electrostatic forces. PMID:27036002

  12. Characteristics of motive force derived from trajectory analysis of Amoeba proteus.

    PubMed

    Masaki, Noritaka; Miyoshi, Hiromi; Tsuchiya, Yoshimi

    2007-01-01

    We used a monochromatic charge-coupled-device camera to observe the migration behavior of Amoeba proteus every 5 s over a time course of 10000 s in order to investigate the characteristics of its centroid movement (cell velocity) over the long term. Fourier transformation of the time series of the cell velocity revealed that its power spectrum exhibits a Lorentz type profile with a relaxation time of a few hundred seconds. Moreover, some sharp peaks were found in the power spectrum, where the ratios of any two frequencies corresponding to the peaks were expressed as simple rational numbers. Analysis of the trajectory using a Langevin equation showed that the power spectrum reflects characteristics of the cell's motive force. These results suggest that some phenomena relating to the cell's motility, such as protoplasmic streaming and the sol-gel transformation of actin filaments, which seem to be independent phenomena and have different relaxation times, interact with each other and cooperatively participate in the generation process of the motive force.

  13. Surface force measurements and simulations of mussel-derived peptide adhesives on wet organic surfaces.

    PubMed

    Levine, Zachary A; Rapp, Michael V; Wei, Wei; Mullen, Ryan Gotchy; Wu, Chun; Zerze, Gül H; Mittal, Jeetain; Waite, J Herbert; Israelachvili, Jacob N; Shea, Joan-Emma

    2016-04-19

    Translating sticky biological molecules-such as mussel foot proteins (MFPs)-into synthetic, cost-effective underwater adhesives with adjustable nano- and macroscale characteristics requires an intimate understanding of the glue's molecular interactions. To help facilitate the next generation of aqueous adhesives, we performed a combination of surface forces apparatus (SFA) measurements and replica-exchange molecular dynamics (REMD) simulations on a synthetic, easy to prepare, Dopa-containing peptide (MFP-3s peptide), which adheres to organic surfaces just as effectively as its wild-type protein analog. Experiments and simulations both show significant differences in peptide adsorption on CH3-terminated (hydrophobic) and OH-terminated (hydrophilic) self-assembled monolayers (SAMs), where adsorption is strongest on hydrophobic SAMs because of orientationally specific interactions with Dopa. Additional umbrella-sampling simulations yield free-energy profiles that quantitatively agree with SFA measurements and are used to extract the adhesive properties of individual amino acids within the context of MFP-3s peptide adhesion, revealing a delicate balance between van der Waals, hydrophobic, and electrostatic forces.

  14. Electrocatalytic Alcohol Oxidation with TEMPO and Bicyclic Nitroxyl Derivatives: Driving Force Trumps Steric Effects.

    PubMed

    Rafiee, Mohammad; Miles, Kelsey C; Stahl, Shannon S

    2015-11-25

    Bicyclic nitroxyl derivatives, such as 2-azaadamantane N-oxyl (AZADO) and 9-azabicyclo[3.3.1]nonane N-oxyl (ABNO), have emerged as highly effective alternatives to TEMPO-based catalysts for selective oxidation reactions (TEMPO = 2,2,6,6-tetramethyl-1-piperidine N-oxyl). Their efficacy is widely attributed to their smaller steric profile; however, electrocatalysis studies described herein show that the catalytic activity of nitroxyls is more strongly affected by the nitroxyl/oxoammonium redox potential than by steric effects. The inexpensive, high-potential TEMPO derivative, 4-acetamido-TEMPO (ACT), exhibits higher electrocatalytic activity than AZADO and ABNO for the oxidation of primary and secondary alcohols. Mechanistic studies provide insights into the origin of these unexpected reactivity trends. The superior activity of ACT is especially noteworthy at high pH, where bicyclic nitroxyls are inhibited by formation of an oxoammonium hydroxide adduct.

  15. RADIAL FLOW PATTERN OF A SLOW CORONAL MASS EJECTION

    SciTech Connect

    Feng, Li; Gan, Weiqun; Inhester, Bernd

    2015-06-01

    Height–time plots of the leading edge of coronal mass ejections (CMEs) have often been used to study CME kinematics. We propose a new method to analyze the CME kinematics in more detail by determining the radial mass transport process throughout the entire CME. Thus, our method is able to estimate not only the speed of the CME front but also the radial flow speed inside the CME. We have applied this method to a slow CME with an average leading edge speed of about 480 km s{sup −1}. In the Lagrangian frame, the speeds of the individual CME mass elements stay almost constant within 2 and 15 R{sub S}, the range over which we analyzed the CME. Hence, we have no evidence of net radial forces acting on parts of the CME in this range or of a pile up of mass ahead of the CME. We find evidence that the leading edge trajectory obtained by tie-pointing may gradually lag behind the Lagrangian front-side trajectories derived from our analysis. Our results also allow a much more precise estimate of the CME energy. Compared with conventional estimates using the CME total mass and leading edge motion, we find that the latter may overestimate the kinetic energy and the gravitational potential energy.

  16. An electromagnetic compressive force by cell exciter stimulates chondrogenic differentiation of bone marrow-derived mesenchymal stem cells.

    PubMed

    Park, Sang-Hyug; Sim, Woo Young; Park, Sin Wook; Yang, Sang Sik; Choi, Byung Hyune; Park, So Ra; Park, Kwideok; Min, Byoung-Hyun

    2006-11-01

    In this study, we present a biological micro-electromechanical system and its application to the chondrogenic differentiation of rabbit bone marrow-derived mesenchymal stem cells (MSCs). Actuated by an electromagnetic force, the micro cell exciter was designed to deliver a cyclic compressive load (CCL) with various magnitudes. Two major parts in the system are an actuator and a cartridge-type chamber. The former has a permanent magnet and coil, and the latter is equipped with 7 sample dishes and 7 metal caps. Mixed with a 2.4% alginate solution, the alginate/MSC layers were positioned in the sample dishes; the caps contained chondrogenic defined medium without transforming growth factor-beta (TGF-beta). Once powered, the actuator coil-derived electromagnetic force pulled the metal caps down, compressing the samples. The cyclic load was given at 1-Hz frequency for 10 min twice a day. Samples in the dishes without a cap served as a control. The samples were analyzed at 3, 5, and 7 days after stimulation for cell viability, biochemical assays, histologic features, immunohistochemistry, and gene expression of the chondrogenic markers. Applied to the alginate/MSC layer, the CCL system enhanced the synthesis of cartilage-specific matrix proteins and the chondrogenic markers, such as aggrecan, type II collagen, and Sox9. We found that the micromechanically exerted CCL by the cell exciter was very effective in enhancing the chondrogenic differentiation of MSCs, even without using exogenous TGF-beta.

  17. Altered calcium handling and increased contraction force in human embryonic stem cell derived cardiomyocytes following short term dexamethasone exposure

    SciTech Connect

    Kosmidis, Georgios; Bellin, Milena; Ribeiro, Marcelo C.; Meer, Berend van; Ward-van Oostwaard, Dorien; Passier, Robert; Tertoolen, Leon G.J.; Mummery, Christine L.; Casini, Simona

    2015-11-27

    One limitation in using human pluripotent stem cell derived cardiomyocytes (hPSC-CMs) for disease modeling and cardiac safety pharmacology is their immature functional phenotype compared with adult cardiomyocytes. Here, we report that treatment of human embryonic stem cell derived cardiomyocytes (hESC-CMs) with dexamethasone, a synthetic glucocorticoid, activated glucocorticoid signaling which in turn improved their calcium handling properties and contractility. L-type calcium current and action potential properties were not affected by dexamethasone but significantly faster calcium decay, increased forces of contraction and sarcomeric lengths, were observed in hESC-CMs after dexamethasone exposure. Activating the glucocorticoid pathway can thus contribute to mediating hPSC-CMs maturation. - Highlights: • Dexamethasone accelerates Ca{sup 2+} transient decay in hESC-CMs. • Dexamethasone enhances SERCA and NCX function in hESC-CMs. • Dexamethasone increases force of contraction and sarcomere length in hESC-CMs. • Dexamethasone does not alter I{sub Ca,L} and action potential characteristics in hESC-CMs.

  18. Test and evaluation of shale derived jet fuel by the United States Air Force

    SciTech Connect

    Delaney, C.L.

    1985-01-01

    In June 1980, the United States Congress passed the Energy Security Act which provided for the formation of the United States Synthetic Fuels Corporation and amended the Defense Production Act of 1950 to provide for synthetic fuels for the Department of Defense (DOD). A subsequent law, P.L., 96-304, appropriated up to $20 billion for financial incentives to foster a national synthetic fuel industry. The initial synthetic fuel project funded under the Energy Security Act is the Unocal Parachute Creek Project in Colorado with an expected shale oil production of 10,000 bbls/day. The Defense Fuel Supply Center (DFSC) contracted with Gary Energy Refining Company, Fruita, Colorado to provide approximately 5,000 bbls/day of shale JP-4 for the United States Air Force (USAF) using crude from the Parachute Creek Project, with initial deliveries to begin in 1985.

  19. Regulation of endothelium-derived vasoactive autacoid production by hemodynamic forces.

    PubMed

    Busse, Rudi; Fleming, Ingrid

    2003-01-01

    Endothelial cells, which are situated at the interface between blood and the vessel wall, have a crucial role in controlling vascular tone and homeostasis, particularly in determining the expression of pro-atherosclerotic and anti-atherosclerotic genes. Many of these effects are mediated by changes in the generation and release of endothelium-derived autacoids [from the Greek autos (self) and akos (remedy)], which are generally short-lived and locally acting. In vivo, endothelial cells are constantly subjected to mechanical stimulation, which in turn determines the acute production of autacoids and the levels of autacoid-producing enzymes.

  20. Expanded Large-Scale Forcing Properties Derived from the Multiscale Data Assimilation System and Its Application to Single-Column Models

    NASA Astrophysics Data System (ADS)

    Feng, S.; Li, Z.; Liu, Y.; Lin, W.; Toto, T.; Vogelmann, A. M.; Fridlind, A. M.

    2013-12-01

    We present an approach to derive large-scale forcing that is used to drive single-column models (SCMs) and cloud resolving models (CRMs)/large eddy simulation (LES) for evaluating fast physics parameterizations in climate models. The forcing fields are derived by use of a newly developed multi-scale data assimilation (MS-DA) system. This DA system is developed on top of the NCEP Gridpoint Statistical Interpolation (GSI) System and is implemented in the Weather Research and Forecasting (WRF) model at a cloud resolving resolution of 2 km. This approach has been applied to the generation of large scale forcing for a set of Intensive Operation Periods (IOPs) over the Atmospheric Radiation Measurement (ARM) Climate Research Facility's Southern Great Plains (SGP) site. The dense ARM in-situ observations and high-resolution satellite data effectively constrain the WRF model. The evaluation shows that the derived forcing displays accuracies comparable to the existing continuous forcing product and, overall, a better dynamic consistency with observed cloud and precipitation. One important application of this approach is to derive large-scale hydrometeor forcing and multiscale forcing, which is not provided in the existing continuous forcing product. It is shown that the hydrometeor forcing poses an appreciable impact on cloud and precipitation fields in the single-column model simulations. The large-scale forcing exhibits a significant dependency on domain-size that represents SCM grid-sizes. Subgrid processes often contribute a significant component to the large-scale forcing, and this contribution is sensitive to the grid-size and cloud-regime.

  1. Single-Molecule Tribology: Force Microscopy Manipulation of a Porphyrin Derivative on a Copper Surface.

    PubMed

    Pawlak, Rémy; Ouyang, Wengen; Filippov, Alexander E; Kalikhman-Razvozov, Lena; Kawai, Shigeki; Glatzel, Thilo; Gnecco, Enrico; Baratoff, Alexis; Zheng, Quanshui; Hod, Oded; Urbakh, Michael; Meyer, Ernst

    2016-01-26

    The low-temperature mechanical response of a single porphyrin molecule attached to the apex of an atomic force microscope (AFM) tip during vertical and lateral manipulations is studied. We find that approach-retraction cycles as well as surface scanning with the terminated tip result in atomic-scale friction patterns induced by the internal reorientations of the molecule. With a joint experimental and computational effort, we identify the dicyanophenyl side groups of the molecule interacting with the surface as the dominant factor determining the observed frictional behavior. To this end, we developed a generalized Prandtl-Tomlinson model parametrized using density functional theory calculations that includes the internal degrees of freedom of the side group with respect to the core and its interactions with the underlying surface. We demonstrate that the friction pattern results from the variations of the bond length and bond angles between the dicyanophenyl side group and the porphyrin backbone as well as those of the CN group facing the surface during the lateral and vertical motion of the AFM tip.

  2. Radial heat flux transformer

    NASA Technical Reports Server (NTRS)

    Basiulis, A.; Buzzard, R. J.

    1971-01-01

    Unit moves heat radially from small diameter shell to larger diameter shell, or vice versa, with negligible temperature drop, making device useful wherever heating or cooling of concentrically arranged materials, substances, and structures is desired.

  3. Atomic force and scanning tunneling microscopy imaging of graphene nanosheets derived from graphite oxide.

    PubMed

    Paredes, J I; Villar-Rodil, S; Solís-Fernández, P; Martínez-Alonso, A; Tascón, J M D

    2009-05-19

    Graphene nanosheets produced in the form of stable aqueous dispersions by chemical reduction of graphene oxide and deposited onto graphite substrates have been investigated by atomic force and scanning tunneling microscopy (AFM/STM). The chemically reduced graphene oxide nanosheets were hardly distinguishable from their unreduced counterparts in the topographic AFM images. However, they could be readily discriminated through phase imaging in the attractive regime of tapping-mode AFM, probably because of differences in hydrophilicity arising from their distinct oxygen contents. The chemically reduced nanosheets displayed a smoothly undulated, globular morphology on the nanometer scale, with typical vertical variations in the subnanometer range and lateral feature sizes of approximately 5-10 nm. Such morphology was attributed to be the result of significant structural disorder in the carbon skeleton, which originates during the strong oxidation that leads to graphene oxide and remains after chemical reduction. Direct evidence of structural disorder was provided by atomic-scale STM imaging, which revealed an absence of long-range periodicity in the graphene nanosheets. Only structured domains a few nanometers large were observed instead. Likewise, the nanosheet edges appeared atomically rough and ill-defined, though smooth on the nanometer scale. The unreduced graphene oxide nanosheets could only be imaged by STM at very low tunneling currents (approximately 1 pA), being visualized in some cases with inverted contrast relative to the graphite substrate, a result that was attributed to their extremely low conductivity. Complementary characterization of the unreduced and chemically reduced nanosheets was carried out by thermogravimetric analysis as well as UV-visible absorption and X-ray photoelectron and Raman spectroscopies. In particular, the somewhat puzzling Raman results were interpreted to be the result of an amorphous character of the graphene oxide material.

  4. Diagnosing Tropical Divergent Circulations From Satellite-Derived Diabatic Forcing and Variational Integral Constraints

    NASA Technical Reports Server (NTRS)

    Robertson, Franklin R.; Lu, H.-I.; Goodman, H. Michael (Technical Monitor)

    2001-01-01

    Large-scale divergent circulations are part of the atmospheric dynamic response to diabatic heating from condensation, radiative processes, and surface energy fluxes. Vertical motion and the associated divergent wind is thus intimately tied to the hydrologic cycle and the global beat balance. Despite its importance, the divergent circulation is too small in comparison to the rotational flow to measure directly with any accuracy. Vertical motions are recovered diagnostically from reanalyses and, as such, are subject to shortcomings in model physics, numerics, and data availability. While reanalysis estimates of tropical divergent circulations are much improved over those from the Global Weather Experiment, there are still substantial differences between products from operational centers. This is because these circulations are still forced largely by model physics and only secondarily by observations. In order to produce a refined estimate of tropical divergence and its interannual variability we have used a number of remotely-sensed data sets along with variational constraints to improve upon reanalysis estimates. Among these are: precipitation from SSM/I and GPCP, TOVS Path-A vertical cloud distributions; ISCCP radiative cooling rates; TOA radiative fluxes from ERBS, surface radiative fluxes from the SRB project, and surface latent and sensible flux estimates from SSM/I. The TOVS Path-A data constrain the divergent outflow in precipitating regions to have the same vertical structure as observed cloudiness. Using integral constraints for moisture, heat, and mass balance, we retrieve consistent divergent wind flows. We examine the ability of this type analysis to capture regional details of ENSO related perturbations to the divergent wind and associated tropical energy balance. Precipitation from satellite is found to be the major constraint in supplying this horizontal structure. We also consider the ability of this analysis to quantify integrated (land vs. ocean

  5. Effect of Noise and Flow Field Resolution on the Evaluation of Fluid Dynamic Forces on Bodies Using only the Velocity Field and its Derivatives

    NASA Astrophysics Data System (ADS)

    Breda, Maria Cecilia; Krueger, Paul S.

    2010-11-01

    Determining unsteady fluid dynamic forces on bodies using only measurements of the velocity field and its derivatives is essential in many investigations, including studies of freely swimming or flying animals. In this project, all terms in a control-volume force equation utilizing only the velocity field and its derivatives discussed by Noca et al. (J. Fluids Struct., 13, 551 - 578) will be analyzed with regard to the influence of flow field noise and resolution to determine which terms dominate the error in the computed force and which factor has the greatest effect on the error. Using analytical and computational flow fields for which the lift and drag forces are known, irregularities found in real experimental results including noise and reduced spatial/temporal resolution will be added to assess their effect on the computed forces. Results for several canonical flows will be presented.

  6. Improved snowmelt simulations with a canopy model forced with photo-derived direct beam canopy transmissivity

    NASA Astrophysics Data System (ADS)

    Musselman, Keith N.; Molotch, Noah P.; Margulis, Steven A.; Lehning, Michael; Gustafsson, David

    2012-10-01

    The predictive capacity of a physically based snow model to simulate point-scale, subcanopy snowmelt dynamics is evaluated in a mixed conifer forest, southern Sierra Nevada, California. Three model scenarios each providing varying levels of canopy structure detail were tested. Simulations of three water years initialized at locations of 24 ultrasonic snow depth sensors were evaluated against observations of snow water equivalent (SWE), snow disappearance date, and volumetric soil water content. When canopy model parameters canopy openness and effective leaf area index were obtained from satellite and literature-based sources, respectively, the model was unable to resolve the variable subcanopy snowmelt dynamics. When canopy parameters were obtained from hemispherical photos, the improvements were not statistically significant. However, when the model was modified to accept photo-derived time-varying direct beam canopy transmissivity, the error in the snow disappearance date was reduced by as much as one week and positive and negative biases in melt-season SWE and snow cover duration were significantly reduced. Errors in the timing of soil meltwater fluxes were reduced by 11 days on average. The optimum aggregated temporal model resolution of direct beam canopy transmissivity was determined to be 30 min; hourly averages performed no better than the bulk canopy scenarios and finer time steps did not increase overall model accuracy. The improvements illustrate the important contribution of direct shortwave radiation to subcanopy snowmelt and confirm the known nonlinear melt behavior of snow cover.

  7. R.E.D. Server: a web service for deriving RESP and ESP charges and building force field libraries for new molecules and molecular fragments

    PubMed Central

    Vanquelef, Enguerran; Simon, Sabrina; Marquant, Gaelle; Garcia, Elodie; Klimerak, Geoffroy; Delepine, Jean Charles; Cieplak, Piotr; Dupradeau, François-Yves

    2011-01-01

    R.E.D. Server is a unique, open web service, designed to derive non-polarizable RESP and ESP charges and to build force field libraries for new molecules/molecular fragments. It provides to computational biologists the means to derive rigorously molecular electrostatic potential-based charges embedded in force field libraries that are ready to be used in force field development, charge validation and molecular dynamics simulations. R.E.D. Server interfaces quantum mechanics programs, the RESP program and the latest version of the R.E.D. tools. A two step approach has been developed. The first one consists of preparing P2N file(s) to rigorously define key elements such as atom names, topology and chemical equivalencing needed when building a force field library. Then, P2N files are used to derive RESP or ESP charges embedded in force field libraries in the Tripos mol2 format. In complex cases an entire set of force field libraries or force field topology database is generated. Other features developed in R.E.D. Server include help services, a demonstration, tutorials, frequently asked questions, Jmol-based tools useful to construct PDB input files and parse R.E.D. Server outputs as well as a graphical queuing system allowing any user to check the status of R.E.D. Server jobs. PMID:21609950

  8. R.E.D. Server: a web service for deriving RESP and ESP charges and building force field libraries for new molecules and molecular fragments.

    PubMed

    Vanquelef, Enguerran; Simon, Sabrina; Marquant, Gaelle; Garcia, Elodie; Klimerak, Geoffroy; Delepine, Jean Charles; Cieplak, Piotr; Dupradeau, François-Yves

    2011-07-01

    R.E.D. Server is a unique, open web service, designed to derive non-polarizable RESP and ESP charges and to build force field libraries for new molecules/molecular fragments. It provides to computational biologists the means to derive rigorously molecular electrostatic potential-based charges embedded in force field libraries that are ready to be used in force field development, charge validation and molecular dynamics simulations. R.E.D. Server interfaces quantum mechanics programs, the RESP program and the latest version of the R.E.D. tools. A two step approach has been developed. The first one consists of preparing P2N file(s) to rigorously define key elements such as atom names, topology and chemical equivalencing needed when building a force field library. Then, P2N files are used to derive RESP or ESP charges embedded in force field libraries in the Tripos mol2 format. In complex cases an entire set of force field libraries or force field topology database is generated. Other features developed in R.E.D. Server include help services, a demonstration, tutorials, frequently asked questions, Jmol-based tools useful to construct PDB input files and parse R.E.D. Server outputs as well as a graphical queuing system allowing any user to check the status of R.E.D. Server jobs.

  9. Arctic Stratus Cloud Properties and Radiative Forcing Derived from Ground-Based Data Collected at Barrow, Alaska.

    NASA Astrophysics Data System (ADS)

    Dong, Xiquan; Mace, Gerald G.

    2003-02-01

    A record of single-layer and overcast low-level Arctic stratus cloud properties has been generated using data collected from May to September 2000 at the Atmospheric Radiation Measurement (ARM) North Slope of Alaska (NSA) (71.3°N, 156.6°W) site near Barrow, Alaska. The record includes liquid-phase and liquid dominant mixed-phase Arctic stratus macrophysical, microphysical, and radiative properties, as well as surface radiation budget and cloud radiative forcing. The macrophysical properties consist of cloud fractions, cloud-base/top heights and temperatures, and cloud thickness derived from a ground-based radar and lidar pair, and rawinsonde sounding. The microphysical properties include cloud liquid water path and content, and cloud-droplet effective radius and number concentration obtained from microwave radiometer brightness temperature measurements, and the new cloud parameterization. The radiative properties contain cloud optical depth, effective solar transmission, and surface/cloud/top-of-atmosphere albedos derived from the new cloud parameterization and standard Epply precision spectral pyranometers. The shortwave, longwave, and net cloud radiative forcings at the surface are inferred from measurements by standard Epply precision spectral pyranometers and pyrgeometers. There are approximately 300 h and more than 3600 samples (5-min resolution) of single-layer and overcast low-level stratus during the study period. The 10-day averaged total and low-level cloud (Ztop < 3 km) fractions are 0.87 and 0.55, and low-level cloud-base and -top heights are around 0.4 and 0.8 km. The cloud-droplet effective radii and number concentrations in the spring are similar to midlatitude continental stratus cloud microphysical properties, and in the summer they are similar to midlatitude marine stratus clouds. The total cloud fractions in this study show good agreement with the satellite and surface results compiled from data collected during the First International

  10. Radial turbine cooling

    NASA Technical Reports Server (NTRS)

    Roelke, Richard J.

    1992-01-01

    Radial turbines have been used extensively in many applications including small ground based electrical power generators, automotive engine turbochargers and aircraft auxiliary power units. In all of these applications the turbine inlet temperature is limited to a value commensurate with the material strength limitations and life requirements of uncooled metal rotors. To take advantage of all the benefits that higher temperatures offer, such as increased turbine specific power output or higher cycle thermal efficiency, requires improved high temperature materials and/or blade cooling. Extensive research is on-going to advance the material properties of high temperature superalloys as well as composite materials including ceramics. The use of ceramics with their high temperature potential and low cost is particularly appealing for radial turbines. However until these programs reach fruition the only way to make significant step increases beyond the present material temperature barriers is to cool the radial blading.

  11. Radial plant growth.

    PubMed

    Tonn, Nina; Greb, Thomas

    2017-09-11

    One of the extraordinary features of plants is their growth capacity. Depending on the species and the environment, body forms are manifold and, at the same time, constantly reshaped. An important basis of this plastic variation and life-long accumulation of biomass is radial growth. Here, we use this term to describe the ability to grow in girth by the formation of wood, bast and cork. The more technical term for radial growth is secondary growth, which distinguishes the process from primary growth taking place at the tips of stems and roots during plant elongation. Copyright © 2017 Elsevier Ltd. All rights reserved.

  12. Radially uniform electron source

    NASA Technical Reports Server (NTRS)

    Mccomas, D.; Bame, S. J.

    1982-01-01

    A thermionic electron source capable of producing uniform count rates in a number of channel electron multipliers simultaneously was required for conditioning multipliers for an extended space mission. It was found that a straight tungsten filament in the center of a cylindrically symmetric geometry surrounded by an array of multipliers emits a radially asymmetric distribution of electrons that changes with time. A source was developed which successfully produces a time-independent radially uniform distribution of electrons by moving the filament out of the direct line of sight and replacing it with a centrally located electron 'cloud.'

  13. Radial transport and momentum exchange in an axial compressor

    SciTech Connect

    Dring, R.P. )

    1993-07-01

    The objective of this work was to examine radial transport in axial compressors from two perspectives. The first was to compare the mixing coefficient based on a secondary flow model (using measured radial velocities) with that based on a turbulent diffusion model. The second was to use measured airfoil pressure forces and momentum changes to assess the validity of the assumption of diffusive radial transport, which is common to both models. These examinations were carried out at both design and off-design conditions as well as for two rotor tip clearances. In general it was seen that radial mixing was strongest near the hub and that it increased dramatically at near-stall conditions. It was also seen that radial transport could cause large differences ([approx] 100 percent) between the force on an airfoil and the change in momentum across the airfoil at the same spanwise location.

  14. Repeated forced swimming impairs prepulse inhibition and alters brain-derived neurotrophic factor and astroglial parameters in rats.

    PubMed

    Borsoi, Milene; Antonio, Camila Boque; Müller, Liz Girardi; Viana, Alice Fialho; Hertzfeldt, Vivian; Lunardi, Paula Santana; Zanotto, Caroline; Nardin, Patrícia; Ravazzolo, Ana Paula; Rates, Stela Maris Kuze; Gonçalves, Carlos-Alberto

    2015-01-01

    Glutamate perturbations and altered neurotrophin levels have been strongly associated with the neurobiology of neuropsychiatric disorders. Environmental stress is a risk factor for mood disorders, disrupting glutamatergic activity in astrocytes in addition to cognitive behaviours. Despite the negative impact of stress-induced neuropsychiatric disorders on public health, the molecular mechanisms underlying the response of the brain to stress has yet to be fully elucidated. Exposure to repeated swimming has proven useful for evaluating the loss of cognitive function after pharmacological and behavioural interventions, but its effect on glutamate function has yet to be fully explored. In the present study, rats previously exposed to repeated forced swimming were evaluated using the novel object recognition test, object location test and prepulse inhibition (PPI) test. In addition, quantification of brain-derived neurotrophic factor (BDNF) mRNA expression and protein levels, glutamate uptake, glutathione, S100B, GluN1 subunit of N-methyl-D-aspartate receptor and calmodulin were evaluated in the frontal cortex and hippocampus after various swimming time points. We found that swimming stress selectively impaired PPI but did not affect memory recognition. Swimming stress altered the frontal cortical and hippocampal BDNF expression and the activity of hippocampal astrocytes by reducing hippocampal glutamate uptake and enhancing glutathione content in a time-dependent manner. In conclusion, these data support the assumption that astrocytes may regulate the activity of brain structures related to cognition in a manner that alters complex behaviours. Moreover, they provide new insight regarding the dynamics immediately after an aversive experience, such as after behavioural despair induction, and suggest that forced swimming can be employed to study altered glutamatergic activity and PPI disruption in rodents.

  15. The fundamental definition of ``radial velocity''

    NASA Astrophysics Data System (ADS)

    Lindegren, Lennart; Dravins, Dainis

    2003-04-01

    Accuracy levels of metres per second require the fundamental concept of ``radial velocity'' for stars and other distant objects to be examined, both as a physical velocity, and as measured by spectroscopic and astrometric techniques. Already in a classical (non-relativistic) framework the line-of-sight velocity component is an ambiguous concept, depending on whether, e.g., the time of light emission (at the object) or that of light detection (by the observer) is used for recording the time coordinate. Relativistic velocity effects and spectroscopic measurements made inside gravitational fields add further complications, causing wavelength shifts to depend, e.g., on the transverse velocity of the object and the gravitational potential at the source. Aiming at definitions that are unambiguous at accuracy levels of 1 m s-1, we analyse different concepts of radial velocity and their interrelations. At this accuracy level, a strict separation must be made between the purely geometric concepts on one hand, and the spectroscopic measurement on the other. Among the geometric concepts we define kinematic radial velocity, which corresponds most closely to the ``textbook definition'' of radial velocity as the line-of-sight component of space velocity; and astrometric radial velocity, which can be derived from astrometric observations. Consistent with these definitions, we propose strict definitions also of the complementary kinematic and astrometric quantities, namely transverse velocity and proper motion. The kinematic and astrometric radial velocities depend on the chosen spacetime metric, and are accurately related by simple coordinate transformations. On the other hand, the observational quantity that should result from accurate spectroscopic measurements is the barycentric radial-velocity measure. This is independent of the metric, and to first order equals the line-of-sight velocity. However, it is not a physical velocity, and cannot be accurately transformed to a

  16. Simulations of Cloud-Radiation Interaction Using Large-Scale Forcing Derived from the CINDY/DYNAMO Northern Sounding Array

    NASA Technical Reports Server (NTRS)

    Wang, Shuguang; Sobel, Adam H.; Fridlind, Ann; Feng, Zhe; Comstock, Jennifer M.; Minnis, Patrick; Nordeen, Michele L.

    2015-01-01

    The recently completed CINDY/DYNAMO field campaign observed two Madden-Julian oscillation (MJO) events in the equatorial Indian Ocean from October to December 2011. Prior work has indicated that the moist static energy anomalies in these events grew and were sustained to a significant extent by radiative feedbacks. We present here a study of radiative fluxes and clouds in a set of cloud-resolving simulations of these MJO events. The simulations are driven by the large-scale forcing data set derived from the DYNAMO northern sounding array observations, and carried out in a doubly periodic domain using the Weather Research and Forecasting (WRF) model. Simulated cloud properties and radiative fluxes are compared to those derived from the S-PolKa radar and satellite observations. To accommodate the uncertainty in simulated cloud microphysics, a number of single-moment (1M) and double-moment (2M) microphysical schemes in the WRF model are tested. The 1M schemes tend to underestimate radiative flux anomalies in the active phases of the MJO events, while the 2M schemes perform better, but can overestimate radiative flux anomalies. All the tested microphysics schemes exhibit biases in the shapes of the histograms of radiative fluxes and radar reflectivity. Histograms of radiative fluxes and brightness temperature indicate that radiative biases are not evenly distributed; the most significant bias occurs in rainy areas with OLR less than 150 W/ cu sq in the 2M schemes. Analysis of simulated radar reflectivities indicates that this radiative flux uncertainty is closely related to the simulated stratiform cloud coverage. Single-moment schemes underestimate stratiform cloudiness by a factor of 2, whereas 2M schemes simulate much more stratiform cloud.

  17. Revisiting the droplet simulation approach to derive force-field parameters for water on molybdenum disulfide from wetting angle measurements

    NASA Astrophysics Data System (ADS)

    Leroy, Frédéric

    2016-10-01

    Owing to its peculiar electronic properties, molybdenum disulfide (MoS2) has been the subject of a growing number of studies in the recent years. In applications, this material and other transition metal dichalcogenides (TMDs) may have to interact with a liquid or polymer phase as well as solutions of biomolecules. It is therefore of primary importance to understand the wetting and adhesion properties of TMDs. Starting from existing models, we derive Lennard-Jones parameters for the interaction between water and the basal plane of MoS2 that are consistent with recent wetting experiments. Molecular dynamics simulations indicate that a stack of only two MoS2 monolayers is necessary to capture the wetting behavior of bulk MoS2. It is found that the Coulomb interaction between water and monolayer and bilayer MoS2 plays no role in the related interfacial thermodynamics. Calculations with the optimized parameters show that the depth of the well of the interaction potential between water and bulk MoS2 is of the order of 8.2 kJ/mol. Such a value is comparable with what was found for graphite and consistent with the fact that the wetting angles of water on graphite and MoS2 are almost equal. The derivation of the force-field parameters is performed using a methodology which, contrary to previous studies, makes a consistent use of droplet calculations. The results of our work should find application in further simulation studies on the wetting behavior of TMDs and other dispersive materials.

  18. Carbon star radial velocities and dark matter in the universe

    NASA Technical Reports Server (NTRS)

    Jura, M.

    1986-01-01

    Optical radial velocities of carbon stars in the Milky Way are compared to center-of-mass velocities derived from CO radio emission produced in their circumstellar envelopes. It seems that there is an intrinsic velocity dispersion in the optically measured radial velocities. If the carbon stars in the dwarf spheroidals behave in a fashion similar to those in the Milky Way, then the use of their optical radial velocities to infer the mass-to-light ratio of dwarf spheroidal galaxies and the nature of the dark matter in the universe is suspect. Measurement of the radial velocities of K giants may possibly avoid these uncertainties associated with atmospheric motions.

  19. Global Comparison of CFD and Wind-Tunnel-Derived Force and Moment Databases for the Space Launch System

    NASA Technical Reports Server (NTRS)

    Hemsch, Michael J.

    2016-01-01

    Recently a very large (739 runs) collection of high-fidelity RANS CFD solutions was obtained for Space Launch System ascent aerodynamics for the vehicle to be used for the first exploratory (unmanned) mission (EM-1). The extensive computations, at full-scale conditions, were originally developed to obtain detailed line and protuberance loads and surface pressures for venting analyses. The line loads were eventually integrated for comparison of the resulting forces and moments to the database that was derived from wind tunnel tests conducted at sub-scale conditions. The comparisons presented herein cover the ranges 0.5 < or = M(infinity) < or = 5, -6deg < or = alpha < or = 6deg, and -6deg < or = beta < or = 6deg. For detailed comparisons, slender-body-theory-based component build-up aero models from missile aerodynamics are used. The differences in the model fit coefficients are shown to be relatively small except for the low supersonic Mach number range, 1.1 < or = M(infinity) < or = 2.0. The analysis is intended to support process improvement and development of uncertainty models.

  20. Inherently-Forced Tensile Strain in Nanodiamond-Derived Onion-like Carbon: Consequences in Defect-Induced Electrochemical Activation

    PubMed Central

    Ko, Young-Jin; Cho, Jung-Min; Kim, Inho; Jeong, Doo Seok; Lee, Kyeong-Seok; Park, Jong-Keuk; Baik, Young-Joon; Choi, Heon-Jin; Lee, Seung-Cheol; Lee, Wook-Seong

    2016-01-01

    We analyzed the nanodiamond-derived onion-like carbon (OLC) as function of synthesis temperature (1000~1400 °C), by high-resolution electron microscopy, electron energy loss spectroscopy, visible-Raman spectroscopy, ultraviolet photoemission spectroscopy, impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. The temperature dependences of the obtained properties (averaged particle size, tensile strain, defect density, density of states, electron transfer kinetics, and electrochemical oxidation current) unanimously coincided: they initially increased and saturated at 1200 °C. It was attributed to the inherent tensile strains arising from (1) the volume expansion associated with the layer-wise diamond-to-graphite transformation of the core, which caused forced dilation of the outer shells during their thermal synthesis; (2) the extreme curvature of the shells. The former origin was dominant over the latter at the outermost shell, of which the relevant evolution in defect density, DOS and electron transfer kinetics determined the electrochemical performances. In detection of dopamine (DA), uric acid (UA) and ascorbic acid (AA) using the OLC as electrode, their oxidation peak currents were enhanced by factors of 15~60 with annealing temperature. Their limit of detection and the linear range of detection, in the post-treatment-free condition, were as excellent as those of the nano-carbon electrodes post-treated by Pt-decoration, N-doping, plasma, or polymer. PMID:27032957

  1. Inherently-Forced Tensile Strain in Nanodiamond-Derived Onion-like Carbon: Consequences in Defect-Induced Electrochemical Activation

    NASA Astrophysics Data System (ADS)

    Ko, Young-Jin; Cho, Jung-Min; Kim, Inho; Jeong, Doo Seok; Lee, Kyeong-Seok; Park, Jong-Keuk; Baik, Young-Joon; Choi, Heon-Jin; Lee, Seung-Cheol; Lee, Wook-Seong

    2016-04-01

    We analyzed the nanodiamond-derived onion-like carbon (OLC) as function of synthesis temperature (1000~1400 °C), by high-resolution electron microscopy, electron energy loss spectroscopy, visible-Raman spectroscopy, ultraviolet photoemission spectroscopy, impedance spectroscopy, cyclic voltammetry and differential pulse voltammetry. The temperature dependences of the obtained properties (averaged particle size, tensile strain, defect density, density of states, electron transfer kinetics, and electrochemical oxidation current) unanimously coincided: they initially increased and saturated at 1200 °C. It was attributed to the inherent tensile strains arising from (1) the volume expansion associated with the layer-wise diamond-to-graphite transformation of the core, which caused forced dilation of the outer shells during their thermal synthesis; (2) the extreme curvature of the shells. The former origin was dominant over the latter at the outermost shell, of which the relevant evolution in defect density, DOS and electron transfer kinetics determined the electrochemical performances. In detection of dopamine (DA), uric acid (UA) and ascorbic acid (AA) using the OLC as electrode, their oxidation peak currents were enhanced by factors of 15~60 with annealing temperature. Their limit of detection and the linear range of detection, in the post-treatment-free condition, were as excellent as those of the nano-carbon electrodes post-treated by Pt-decoration, N-doping, plasma, or polymer.

  2. The variational explicit polarization potential and analytical first derivative of energy: Towards a next generation force field

    PubMed Central

    Xie, Wangshen; Song, Lingchun; Truhlar, Donald G.; Gao, Jiali

    2008-01-01

    A previous article proposed an electronic structure-based polarizable potential, called the explicit polarization (X-POL) potential, to treat many-body polarization and charge delocalization effects in polypeptides. Here, we present a variational version of the X-POL potential, in which the wave function of the entire molecular system is variationally optimized to yield the minimum total electronic energy. This allows the calculation of analytic gradients, a necessity for efficient molecular dynamics simulations. In this paper, the detailed derivations of the Fock matrix and analytic force are presented and discussed. The calculations involve a double self-consistent-field procedure in which the wave function of each fragment is self-consistently optimized in the presence of other fragments, and in addition the polarization of the entire system is self-consistently optimized. The variational X-POL potential has been implemented in the Chemistry at Harvard Molecular Mechanics (CHARMM) package and tested successfully for small model compounds. PMID:18570492

  3. Variable stator radial turbine

    NASA Technical Reports Server (NTRS)

    Rogo, C.; Hajek, T.; Chen, A. G.

    1984-01-01

    A radial turbine stage with a variable area nozzle was investigated. A high work capacity turbine design with a known high performance base was modified to accept a fixed vane stagger angle moveable sidewall nozzle. The nozzle area was varied by moving the forward and rearward sidewalls. Diffusing and accelerating rotor inlet ramps were evaluated in combinations with hub and shroud rotor exit rings. Performance of contoured sidewalls and the location of the sidewall split line with respect to the rotor inlet was compared to the baseline. Performance and rotor exit survey data are presented for 31 different geometries. Detail survey data at the nozzle exit are given in contour plot format for five configurations. A data base is provided for a variable geometry concept that is a viable alternative to the more common pivoted vane variable geometry radial turbine.

  4. Radial Inflow Turboexpander Redesign

    SciTech Connect

    William G. Price

    2001-09-24

    Steamboat Envirosystems, LLC (SELC) was awarded a grant in accordance with the DOE Enhanced Geothermal Systems Project Development. Atlas-Copco Rotoflow (ACR), a radial expansion turbine manufacturer, was responsible for the manufacturing of the turbine and the creation of the new computer program. SB Geo, Inc. (SBG), the facility operator, monitored and assisted ACR's activities as well as provided installation and startup assistance. The primary scope of the project is the redesign of an axial flow turbine to a radial inflow turboexpander to provide increased efficiency and reliability at an existing facility. In addition to the increased efficiency and reliability, the redesign includes an improved reduction gear design, and improved shaft seal design, and upgraded control system and a greater flexibility of application

  5. Radial pressure flange seal

    DOEpatents

    Batzer, Thomas H.; Call, Wayne R.

    1989-01-01

    This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side.

  6. Radial pressure flange seal

    DOEpatents

    Batzer, T.H.; Call, W.R.

    1989-01-24

    This invention provides an all metal seal for vacuum or pressure vessels or systems. This invention does not use gaskets. The invention uses a flange which fits into a matching groove. Fluid pressure is applied in a chamber in the flange causing at least one of the flange walls to radially press against a side of the groove creating the seal between the flange wall and the groove side. 5 figs.

  7. Radially inhomogeneous bounded plasmas

    NASA Astrophysics Data System (ADS)

    Zakeri-Khatir, H.; Aghamir, F. M.

    2016-07-01

    On the basis of kinetic theory along with self-consistent field equations, the expressions for dielectric tensor of radially inhomogeneous magnetized plasma columns are obtained. The study of dielectric tensor characteristics allows the accurate analysis of the inhomogeneous properties, beyond limitations that exist in the conventional method. Through the Bessel-Fourier transformation, the localized form of material equations in a radially inhomogeneous medium are obtained. In order to verify the integrity of the model and reveal the effect of inhomogeneity, a special case of a cylindrical plasma waveguide completely filled with inhomogeneous magnetized cold plasma was considered. The dispersion relation curves for four families of electromagnetic (EH and HE) and electrostatic (SC and C) modes are obtained and compared with the findings of the conventional model. The numerical analysis indicates that the inhomogeneity effect leads to coupling of electromagnetic and electrostatic modes each having different radial eigen numbers. The study also reveals that the electrostatic modes are more sensitive to inhomogeneous effects than the electromagnetic modes.

  8. Radial nerve palsy

    PubMed Central

    Bumbasirevic, Marko; Palibrk, Tomislav; Lesic, Aleksandar; Atkinson, Henry DE

    2016-01-01

    As a result of its proximity to the humeral shaft, as well as its long and tortuous course, the radial nerve is the most frequently injured major nerve in the upper limb, with its close proximity to the bone making it vulnerable when fractures occur. Injury is most frequently sustained during humeral fracture and gunshot injuries, but iatrogenic injuries are not unusual following surgical treatment of various other pathologies. Treatment is usually non-operative, but surgery is sometimes necessary, using a variety of often imaginative procedures. Because radial nerve injuries are the least debilitating of the upper limb nerve injuries, results are usually satisfactory. Conservative treatment certainly has a role, and one of the most important aspects of this treatment is to maintain a full passive range of motion in all the affected joints. Surgical treatment is indicated in cases when nerve transection is obvious, as in open injuries or when there is no clinical improvement after a period of conservative treatment. Different techniques are used including direct suture or nerve grafting, vascularised nerve grafts, direct nerve transfer, tendon transfer, functional muscle transfer or the promising, newer treatment of biological therapy. Cite this article: Bumbasirevic M, Palibrk T, Lesic A, Atkinson HDE. Radial nerve palsy. EFORT Open Rev 2016;1:286-294. DOI: 10.1302/2058-5241.1.000028. PMID:28461960

  9. Radial Field Piezoelectric Diaphragms

    NASA Technical Reports Server (NTRS)

    Bryant, R. G.; Effinger, R. T., IV; Copeland, B. M., Jr.

    2002-01-01

    A series of active piezoelectric diaphragms were fabricated and patterned with several geometrically defined Inter-Circulating Electrodes "ICE" and Interdigitated Ring Electrodes "ICE". When a voltage potential is applied to the electrodes, the result is a radially distributed electric field that mechanically strains the piezoceramic along the Z-axis (perpendicular to the applied electric field). Unlike other piezoelectric bender actuators, these Radial Field Diaphragms (RFDs) strain concentrically yet afford high displacements (several times that of the equivalent Unimorph) while maintaining a constant circumference. One of the more intriguing aspects is that the radial strain field reverses itself along the radius of the RFD while the tangential strain remains relatively constant. The result is a Z-deflection that has a conical profile. This paper covers the fabrication and characterization of the 5 cm. (2 in.) diaphragms as a function of poling field strength, ceramic thickness, electrode type and line spacing, as well as the surface topography, the resulting strain field and displacement as a function of applied voltage at low frequencies. The unique features of these RFDs include the ability to be clamped about their perimeter with little or no change in displacement, the environmentally insulated packaging, and a highly repeatable fabrication process that uses commodity materials.

  10. Radial velocity studies of cool stars.

    PubMed

    Jones, Hugh R A; Barnes, John; Tuomi, Mikko; Jenkins, James S; Anglada-Escude, Guillem

    2014-04-28

    Our current view of exoplanets is one derived primarily from solar-like stars with a strong focus on understanding our Solar System. Our knowledge about the properties of exoplanets around the dominant stellar population by number, the so-called low-mass stars or M dwarfs, is much more cursory. Based on radial velocity discoveries, we find that the semi-major axis distribution of M dwarf planets appears to be broadly similar to those around more massive stars and thus formation and migration processes might be similar to heavier stars. However, we find that the mass of M dwarf planets is relatively much lower than the expected mass dependency based on stellar mass and thus infer that planet formation efficiency around low-mass stars is relatively impaired. We consider techniques to overcome the practical issue of obtaining good quality radial velocity data for M dwarfs despite their faintness and sustained activity and emphasize (i) the wavelength sensitivity of radial velocity signals, (ii) the combination of radial velocity data from different experiments for robust detection of small amplitude signals, and (iii) the selection of targets and radial velocity interpretation of late-type M dwarfs should consider Hα behaviour.

  11. Antiproton compression and radial measurements

    SciTech Connect

    Andresen, G. B.; Bowe, P. D.; Hangst, J. S.; Bertsche, W.; Butler, E.; Charlton, M.; Humphries, A. J.; Jenkins, M. J.; Joergensen, L. V.; Madsen, N.; Werf, D. P. van der; Bray, C. C.; Chapman, S.; Fajans, J.; Povilus, A.; Wurtele, J. S.; Cesar, C. L.; Lambo, R.; Silveira, D. M.; Fujiwara, M. C.

    2008-08-08

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.

  12. Antiproton compression and radial measurements

    NASA Astrophysics Data System (ADS)

    Andresen, G. B.; Bertsche, W.; Bowe, P. D.; Bray, C. C.; Butler, E.; Cesar, C. L.; Chapman, S.; Charlton, M.; Fajans, J.; Fujiwara, M. C.; Funakoshi, R.; Gill, D. R.; Hangst, J. S.; Hardy, W. N.; Hayano, R. S.; Hayden, M. E.; Humphries, A. J.; Hydomako, R.; Jenkins, M. J.; Jørgensen, L. V.; Kurchaninov, L.; Lambo, R.; Madsen, N.; Nolan, P.; Olchanski, K.; Olin, A.; Page, R. D.; Povilus, A.; Pusa, P.; Robicheaux, F.; Sarid, E.; El Nasr, S. Seif; Silveira, D. M.; Storey, J. W.; Thompson, R. I.; van der Werf, D. P.; Wurtele, J. S.; Yamazaki, Y.

    2008-08-01

    Control of the radial profile of trapped antiproton clouds is critical to trapping antihydrogen. We report detailed measurements of the radial manipulation of antiproton clouds, including areal density compressions by factors as large as ten, achieved by manipulating spatially overlapped electron plasmas. We show detailed measurements of the near-axis antiproton radial profile, and its relation to that of the electron plasma. We also measure the outer radial profile by ejecting antiprotons to the trap wall using an octupole magnet.

  13. Macromolecular triplex zipping observed in derivatives of fungal (1 --> 3)-beta-D-glucan by electron and atomic force microscopy.

    PubMed

    Stokke, B T; Falch, B H; Dentini, M

    2001-05-01

    Scleroglucan, a comb-like branched (1 --> 3)-beta-D-glucan, dissolves in water as a stiff, triple-helical structure with the single glucose branches extending from the surface. The aim of this study is to investigate structural changes in the triple-helical structure associated with selective chemical modification of the side chains. Electron and atomic force microscopy, respectively, were used to investigate the macromolecular structures of aldehyde and carboxylated derivatives of scleroglucan-namely, scleraldehyde and sclerox-with different degrees of substitution. Scleraldehyde was observed to have structures resembling the triplex of the unmodified scleroglucan for all degrees of substitution up to 1.0. Additionally, an increasing tendency to aggregate for the higher degrees of substitution was observed. Fully carboxylated scleroglucan, sclerox(1.0), prepared from solutions at ionic strengths below 1.0M, revealed dispersed, flexible, coil-like structures. This indicates an electrostatic-driven strand separation of the scleroglucan triple-helical structure occurring concomitant with an increasing fraction of the side chains bearing carboxylate groups. Annealed sclerox(1.0) samples in aqueous 1.0 and 1.5M NaCl exhibited partly, or completely, reassociated triplex ensembles, with species ranging from apparently fully zipped linear and circular topologies, partly zipped structures with triplex strand separation occurring at the ends, to dispersed single-strands with random coil-like appearance. This study shows that periodate oxidation of the scleroglucan side chains is not a sufficient modification of the side chains to induce dissociation of the triple-helical structure, whereas further oxidation of the side chains to carboxylic groups dissociates the triple-helical structure when the degree of substitution is above 0.6. Copyright 2001 John Wiley & Sons, Inc. Biopolymers 58: 535-547, 2001

  14. Radial cutting torch

    SciTech Connect

    Robertson, M.C.

    1997-01-08

    The project`s aim is to complete development of the Radial Cutting Torch, a pyrotechnic cutter, for use in all downhole tubular cutting operations in the petroleum industry. Project objectives are to redesign and pressure test nozzle seals to increase product quality, reliability, and manufacturability; improve the mechanical anchor to increase its temperature tolerance and its ability to function in a wider variety of wellbore fluids; and redesign and pressure test the RCT nozzle for operation at pressures from 10 to 20 ksi. The proposal work statement is included in the statement of work for the grant via this reference.

  15. Radial retroiridal linear pigmentation.

    PubMed Central

    Rieger, G

    1981-01-01

    Radial retroiridal pigmented lines found on the peripheral anterior capsule of the lens have been interpreted since their description by Vogt as remnants of the tunica vasculosa retroiridalis (membrana capsulopupillaris). They were found in nearly 5% of adults. A control examination of 1108 children and juveniles failed to reveal a single example. They are therefore thought to be caused by pigment released from the posterior layers of the iris, particularly near the pupillary border in old age, as a result of constant abrasive movements of the iris on the anterior surface of the lens. Images PMID:7326223

  16. Radial Reflection diffraction tomorgraphy

    DOEpatents

    Lehman, Sean K

    2013-11-19

    A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

  17. Radial reflection diffraction tomography

    DOEpatents

    Lehman, Sean K.

    2012-12-18

    A wave-based tomographic imaging method and apparatus based upon one or more rotating radially outward oriented transmitting and receiving elements have been developed for non-destructive evaluation. At successive angular locations at a fixed radius, a predetermined transmitting element can launch a primary field and one or more predetermined receiving elements can collect the backscattered field in a "pitch/catch" operation. A Hilbert space inverse wave (HSIW) algorithm can construct images of the received scattered energy waves using operating modes chosen for a particular application. Applications include, improved intravascular imaging, bore hole tomography, and non-destructive evaluation (NDE) of parts having existing access holes.

  18. Harvesting the radial artery

    PubMed Central

    Osterday, Robert M.; Brodman, Richard F.

    2013-01-01

    The radial artery (RA) has emerged as an important arterial graft for coronary bypass surgery. With improving five-year patency rates and increasing uptake, great attention has been focused on the optimal conduit harvesting technique. We herein present our approach to RA harvesting. Prerequisites of a successful harvest include adherence to important anatomical landmarks, protection of the sensory innervation to the volar forearm, and meticulous handling of the RA branches. Regardless of the harvesting methodology chosen, adherence to a “no-touch” technique will optimize the patency and durability of the RA conduit. PMID:23977633

  19. Heterogeneous Force Chains in Cellularized Biopolymer Network

    NASA Astrophysics Data System (ADS)

    Liang, Long; Jones, Christopher Allen Rucksack; Sun, Bo; Jiao, Yang

    Biopolymer Networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the mechanical response of a model biopolymer network due to the active contraction of embedded cells. Specifically, a graph (bond-node) model derived from confocal microscopy data is used to represent the network microstructure, and cell contraction is modeled by applying correlated displacements at specific nodes, representing the focal adhesion sites. A force-based stochastic relaxation method is employed to obtain force-balanced network under cell contraction. We find that the majority of the forces are carried by a small number of heterogeneous force chains emerged from the contracting cells. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to the reorientation induced by cell contraction. Large fluctuations of the forces along different force chains are observed. Importantly, the decay of the forces along the force chains is significantly slower than the decay of radially averaged forces in the system, suggesting that the fibreous nature of biopolymer network structure could support long-range mechanical signaling between cells.

  20. Radial Distance Estimation with Tapered Whisker Sensors.

    PubMed

    Ahn, Sejoon; Kim, DaeEun

    2017-07-19

    Rats use their whiskers as tactile sensors to sense their environment. Active whisking, moving whiskers back and forth continuously, is one of prominent features observed in rodents. They can discriminate different textures or extract features of a nearby object such as size, shape and distance through active whisking. There have been studies to localize objects with artificial whiskers inspired by rat whiskers. The linear whisker model based on beam theory has been used to estimate the radial distance, that is, the distance between the base of the whisker and a target object. In this paper, we investigate deflection angle measurements instead of forces or moments, based on a linear tapered whisker model to see the role of tapered whiskers found in real animals. We analyze how accurately this model estimates the radial distance, and quantify the estimation errors and noise sensitivity. We also compare the linear model simulation and nonlinear numerical solutions. It is shown that the radial distance can be estimated using deflection angles at two different positions on the tapered whisker. We argue that the tapered whisker has an advantage of estimating the radial distance better, as compared to an untapered whisker, and active sensing allows that estimation without the whisker's material property and thickness or the moment at base. In addition, we investigate the potential of passive sensing for tactile localization.

  1. Radial Distance Estimation with Tapered Whisker Sensors

    PubMed Central

    Ahn, Sejoon; Kim, DaeEun

    2017-01-01

    Rats use their whiskers as tactile sensors to sense their environment. Active whisking, moving whiskers back and forth continuously, is one of prominent features observed in rodents. They can discriminate different textures or extract features of a nearby object such as size, shape and distance through active whisking. There have been studies to localize objects with artificial whiskers inspired by rat whiskers. The linear whisker model based on beam theory has been used to estimate the radial distance, that is, the distance between the base of the whisker and a target object. In this paper, we investigate deflection angle measurements instead of forces or moments, based on a linear tapered whisker model to see the role of tapered whiskers found in real animals. We analyze how accurately this model estimates the radial distance, and quantify the estimation errors and noise sensitivity. We also compare the linear model simulation and nonlinear numerical solutions. It is shown that the radial distance can be estimated using deflection angles at two different positions on the tapered whisker. We argue that the tapered whisker has an advantage of estimating the radial distance better, as compared to an untapered whisker, and active sensing allows that estimation without the whisker’s material property and thickness or the moment at base. In addition, we investigate the potential of passive sensing for tactile localization. PMID:28753949

  2. Mechanical Stress Conditioning and Electrical Stimulation Promote Contractility and Force Maturation of Induced Pluripotent Stem Cell-Derived Human Cardiac Tissue.

    PubMed

    Ruan, Jia-Ling; Tulloch, Nathaniel L; Razumova, Maria V; Saiget, Mark; Muskheli, Veronica; Pabon, Lil; Reinecke, Hans; Regnier, Michael; Murry, Charles E

    2016-11-15

    Tissue engineering enables the generation of functional human cardiac tissue with cells derived in vitro in combination with biocompatible materials. Human-induced pluripotent stem cell-derived cardiomyocytes provide a cell source for cardiac tissue engineering; however, their immaturity limits their potential applications. Here we sought to study the effect of mechanical conditioning and electric pacing on the maturation of human-induced pluripotent stem cell-derived cardiac tissues. Cardiomyocytes derived from human-induced pluripotent stem cells were used to generate collagen-based bioengineered human cardiac tissue. Engineered tissue constructs were subjected to different mechanical stress and electric pacing conditions. The engineered human myocardium exhibits Frank-Starling-type force-length relationships. After 2 weeks of static stress conditioning, the engineered myocardium demonstrated increases in contractility (0.63±0.10 mN/mm(2) vs 0.055±0.009 mN/mm(2) for no stress), tensile stiffness, construct alignment, and cell size. Stress conditioning also increased SERCA2 (Sarco/Endoplasmic Reticulum Calcium ATPase 2) expression, which correlated with a less negative force-frequency relationship. When electric pacing was combined with static stress conditioning, the tissues showed an additional increase in force production (1.34±0.19 mN/mm(2)), with no change in construct alignment or cell size, suggesting maturation of excitation-contraction coupling. Supporting this notion, we found expression of RYR2 (Ryanodine Receptor 2) and SERCA2 further increased by combined static stress and electric stimulation. These studies demonstrate that electric pacing and mechanical stimulation promote maturation of the structural, mechanical, and force generation properties of human-induced pluripotent stem cell-derived cardiac tissues. © 2016 American Heart Association, Inc.

  3. High-Speed Tests of Radial-Engine Cowlings

    NASA Technical Reports Server (NTRS)

    Robinson, Russell G.; Becker, John V.

    1939-01-01

    The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the N.A.C.A. 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination mere used in the tests.

  4. High-Speed Tests of Conventional Radial-Engine Cowlings

    NASA Technical Reports Server (NTRS)

    Robinson, Russell G; Becker, John V

    1942-01-01

    The drag characteristics of eight radial-engine cowlings have been determined over a wide speed range in the NACA 8-foot high-speed wind tunnel. The pressure distribution over all cowlings was measured, to and above the speed of the compressibility burble, as an aid in interpreting the force tests. One-fifth-scale models of radial-engine cowlings on a wing-nacelle combination were used in the tests.

  5. Radial Velocities with PARAS

    NASA Astrophysics Data System (ADS)

    Roy, Arpita; Mahadevan, S.; Chakraborty, A.; Pathan, F. M.; Anandarao, B. G.

    2010-01-01

    The Physical Research Laboratory Advanced Radial-velocity All-sky Search (PARAS) is an efficient fiber-fed cross-dispersed high-resolution echelle spectrograph that will see first light in early 2010. This instrument is being built at the Physical Research laboratory (PRL) and will be attached to the 1.2m telescope at Gurushikhar Observatory at Mt. Abu, India. PARAS has a single-shot wavelength coverage of 370nm to 850nm at a spectral resolution of R 70000 and will be housed in a vacuum chamber (at 1x10-2 mbar pressure) in a highly temperature controlled environment. This renders the spectrograph extremely suitable for exoplanet searches with high velocity precision using the simultaneous Thorium-Argon wavelength calibration method. We are in the process of developing an automated data analysis pipeline for echelle data reduction and precise radial velocity extraction based on the REDUCE package of Piskunov & Valenti (2002), which is especially careful in dealing with CCD defects, extraneous noise, and cosmic ray spikes. Here we discuss the current status of the PARAS project and details and tests of the data analysis procedure, as well as results from ongoing PARAS commissioning activities.

  6. Radial SI latches vibration test data review

    NASA Technical Reports Server (NTRS)

    Harrison, P. M.; Smith, J. L.

    1984-01-01

    Dynamic testing of the Space Telescope Scientific Instrument Radial Latches was performed as specified by the designated test criteria. No structural failures were observed during the test. The alignment stability of the instrument simulator was within required tolerances after testing. Particulates were discovered around the latch bases, after testing, due to wearing at the B and C latch interface surfaces. This report covers criteria derivation, testing, and test results.

  7. Intercomparison of atmospheric reanalysis data in the Arctic region: To derive site-specific forcing data for terrestrial models

    NASA Astrophysics Data System (ADS)

    Mori, J.; Saito, K.; Machiya, H.; Yabuki, H.; Ikawa, H.; Ohta, T.; Iijima, Y.; Kotani, A.; Suzuki, R.; Miyazaki, S.; Sato, A.; Hajima, T.; Sueyoshi, T.

    2015-12-01

    An intercomparison project for the Arctic terrestrial (physical and ecosystem) models, GTMIP, is conducted, targeting at improvements in the existing terrestrial schemes, as an activity of the Terrestrial Ecosystem research group in the Arctic of Japan GRENE Arctic Climate Change Research Project (GRENE-TEA). For site simulations for four GRENE-TEA sites (i.e., Fairbanks/AK, Kevo/Finland, Tiksi and Yakutsk/Siberia), we needed to prepare continuous, site-fit forcing data ready to drive the models. Due to scarcity of site observations in the region, however, it was difficult to make such data directly from the observations. Therefore, we decided to create a backbone dataset (Level 0 or Lv0) first by utilizing the reanalysis data to derive the site-specific data (Level 1 or Lv1). For selection of the best dataset for our purpose, we compared four atmospheric reanalysis datasets, i.e., ERA Interim, JRA-55, NCEP/NCAR Reanalysis 1, and NCEP-DOE Reanalysis 2, in terms of the climatic reproducibility (w.r.t. temperature at 2 m and precipitation) in the region north of 60°N. CRU for temperature and GPCP for precipitation were also used for monthly-mean ground-level climate. As we will show ERA-Interim showed the smallest bias for both the parameters in terms of RMSE. Especially, air temperature in the cold period was reproduced better in ERA-Interim than is in JRA-55 or other reanalysis products. Therefore, we created Lv0 from ERA-Interim. Comparison between the site observations and Lv0 showed good agreement except for wind speed at all sites and air temperature at Tiksi, a coastal site in the eastern Siberia. Air temperature of ERA-Interim showed significantly continental characteristics while the site observation more coastal. The 34-year-long, hourly, site-fit continuous data (Lv1) for each of the GRENE-TEA sites was then created from the Lv0 values at the grid point closest to the site, by merging with the observations.

  8. Development of large radial turbine turbochargers

    SciTech Connect

    Winn, K.R.; Hirst, P.; Kay, P.

    1996-12-31

    The use of fully radial turbochargers for medium speed diesel engines have largely been restricted to distillate fuel operation at relatively modest pressure ratios. Pressures on costs per kW have forced the industry to push for increases in rating and range of operation for these machines. The development of a high pressure ratio radial turbocharger with the capability to operate reliably on heavy fuel has become a high priority. This paper discusses the development of a range of such machines to cover engine output of between 500 kW and 1.6 MW. The original design of the first turbocharger in the range, the NAPIER 047, is reviewed together with the development and operational experiences gained to date. These have been incorporated into the latest two turbochargers in the range, the NAPIER 057 and 067. The paper includes descriptions of the means taken to achieve minimum time to market and low cost of manufacture.

  9. TNF-alpha acts via TNFR1 and muscle-derived oxidants to depress myofibrillar force in murine skeletal muscle.

    PubMed

    Hardin, Brian J; Campbell, Kenneth S; Smith, Jeffrey D; Arbogast, Sandrine; Smith, Jacqueline; Moylan, Jennifer S; Reid, Michael B

    2008-03-01

    Tumor necrosis factor-alpha (TNF) diminishes specific force of skeletal muscle. To address the mechanism of this response, we tested the hypothesis that TNF acts via the type 1 (TNFR1) receptor subtype to increase oxidant activity and thereby depress myofibrillar function. Experiments showed that a single intraperitoneal dose of TNF (100 microg/kg) increased cytosolic oxidant activity (P < 0.05) and depressed maximal force of male ICR mouse diaphragm by approximately 25% within 1 h, a deficit that persisted for 48 h. Pretreating animals with the antioxidant Trolox (10 mg/kg) lessened oxidant activity (P < 0.05) and abolished contractile losses in TNF-treated muscle (P < 0.05). Genetic TNFR1 deficiency prevented the rise in oxidant activity and fall in force stimulated by TNF; type 2 TNF receptor deficiency did not. TNF effects on muscle function were evident at the myofibrillar level. Chemically permeabilized muscle fibers from TNF-treated animals had lower maximal Ca2+-activated force (P < 0.02) with no change in Ca2+ sensitivity or shortening velocity. We conclude that TNF acts via TNFR1 to stimulate oxidant activity and depress specific force. TNF effects on force are caused, at least in part, by decrements in function of calcium-activated myofibrillar proteins.

  10. Radial cold trap

    DOEpatents

    Grundy, B.R.

    1981-09-29

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume. 2 figs.

  11. Radial cold trap

    DOEpatents

    Grundy, Brian R.

    1981-01-01

    The radial cold trap comprises a housing having a plurality of mesh bands disposed therein. The mesh bands comprise concentrically arranged bands of mesh with the mesh specific surface area of each band increasing from the outermost mesh band to the innermost mesh band. An inlet nozzle is attached to the outside section of the housing while an outlet nozzle is attached to the inner portion of the housing so as to be concentrically connected to the innermost mesh band. An inlet baffle having orifices therein may be disposed around the outermost mesh band and within the housing for directing the flow of the fluid from the inlet nozzle to the outermost mesh band in a uniform manner. The flow of fluid passes through each consecutive mesh band and into the outlet nozzle. The circular pattern of the symmetrically arranged mesh packing allows for better utilization of the entire cold trap volume.

  12. Derivation of force field parameters for SnO2-H2O surface systems from plane-wave density functional theory calculations.

    PubMed

    Bandura, A V; Sofo, J O; Kubicki, J D

    2006-04-27

    Plane-wave density functional theory (DFT-PW) calculations were performed on bulk SnO2 (cassiterite) and the (100), (110), (001), and (101) surfaces with and without H2O present. A classical interatomic force field has been developed to describe bulk SnO2 and SnO2-H2O surface interactions. Periodic density functional theory calculations using the program VASP (Kresse et al., 1996) and molecular cluster calculations using Gaussian 03 (Frisch et al., 2003) were used to derive the parametrization of the force field. The program GULP (Gale, 1997) was used to optimize parameters to reproduce experimental and ab initio results. The experimental crystal structure and elastic constants of SnO2 are reproduced reasonably well with the force field. Furthermore, surface atom relaxations and structures of adsorbed H2O molecules agree well between the ab initio and force field predictions. H2O addition above that required to form a monolayer results in consistent structures between the DFT-PW and classical force field results as well.

  13. Radial Mixing in Turbomachines.

    DTIC Science & Technology

    1988-02-01

    entrainment rate F force defect thickness f blade force, wake model function (eq 9.3) g wake model function (eq 9.4) H shape factor , H Head’s shape factor h...and wake predictions . A new mixing procedure based on the explicit computation of the full transport equation is proposed. This full computation...8217 caused by an overall non-uniform inlet flow as predicted by a through-flow computation, and an ’end-wall boundary layer passage vortex’. 2.2

  14. Nonaxisymmetric incompressible hydrostatic pressure effects in radial face seals

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1976-01-01

    A flat seal having an angular misalinement is analyzed, taking into account the radial variations in seal clearance. An analytical solution for axial force, tilting moment, and leakage is presented that covers the whole range from zero to full angular misalinement. Nonaxisymmetric hydrostatic pressures due to the radial variations in the film thickness have a considerable effect on seal stability. When the high pressure is on the outer periphery of the seal, both the axial force and the tilting moment are nonrestoring. The case of high-pressure seals where cavitation is eliminated is discussed, and the possibility of dynamic instability is pointed out.

  15. Forced collapse of the blastocoel enhances survival of cryotop vitrified bovine hatching/hatched blastocysts derived from in vitro fertilization and somatic cell nuclear transfer.

    PubMed

    Min, Sung-Hun; Lee, Enok; Son, Hyeong-Hoon; Yeon, Ji-Yeong; Koo, Deog-Bon

    2013-04-01

    Freezing of bovine blastocysts has been widely used to improve the feasibility of cattle production by the embryo transfer technique. However, the low survival of vitrified-warmed embryos and their further development are crucial problems. Particularly, the production of offspring in vitrified-warmed bovine hatching/hatched blastocysts derived from in vitro fertilization (IVF) and somatic cell nuclear transfer (SCNT) is very low. Thus, we examined the effects of forced blastocoel collapse (FBC) before vitrification of bovine IVF- and SCNT-derived hatching/hatched embryos on the survival rate and apoptosis index after warming. Under optimal conditions, the overall survival rates in vitrified-warmed bovine IVF- and SCNT-derived hatching/hatched blastocysts were higher in FBC groups than in non-FBC groups (p<0.05). The total cell numbers of vitrified-warmed hatching/hatched blastocysts were higher in FBC groups than in non-FBC groups (p<0.05). Otherwise, the number of apoptotic positive cells of vitrified-warmed hatching/hatched blastocysts was lower in FBC groups than in non-FBC groups (p<0.05). Taken together, these findings suggest that forced collapse of the blastocoel using a pulled Pasteur pipette is an effective pretreatment technique for vitrification of bovine IVF- and SCNT-derived hatching/hatched blastocysts.

  16. A model for the radiative forcing during ACE-Asia derived from CIRPAS Twin Otter and R/V Ronald H. Brown data and comparison with observations

    NASA Astrophysics Data System (ADS)

    Conant, William C.; Seinfeld, John H.; Wang, Jian; Carmichael, Gregory R.; Tang, Youhua; Uno, Itsushi; Flatau, Piotr J.; Markowicz, Krzysztof M.; Quinn, Patricia K.

    2003-12-01

    Vertical profiles of aerosol size, composition, and hygroscopic behavior from Center for Interdisciplinary Remotely Piloted Aircraft Studies (CIRPAS) Twin Otter and National Oceanic and Atmospheric Administration R/V Ronald H. Brown observations are used to construct a generic optical model of the Asian Pacific Regional Aerosol Characterization Experiment (ACE-Asia) aerosol. The model accounts for sulfate, black carbon, organic carbon, sea salt, and mineral dust. The effects of relative humidity and mixing assumptions (internal versus external, coating of dust by pollutants) are explicitly accounted for. The aerosol model is integrated with a Monte Carlo radiative transfer model to compute direct radiative forcing in the solar spectrum. The predicted regional average surface aerosol forcing efficiency (change in clear-sky radiative flux per unit aerosol optical depth at 500 nm) during the ACE-Asia intensive period is -65 Wm-2 for pure dust and -60 Wm-2 for pure pollution aerosol (clear skies). A three-dimensional atmospheric chemical transport model (Chemical Weather Forecast System (CFORS)) is used with the radiative transfer model to derive regional radiative forcing during ACE-Asia in clear and cloudy skies. Net regional solar direct radiative forcing during the 5-15 April 2001 dust storm period is -3 Wm-2 at the top of the atmosphere and -17 W m-2 at the surface for the region from 20°N to 50°N and 100°E to 150°E when the effects of clouds on the direct forcing are included. The model fluxes and forcing efficiencies are found to be in good agreement with surface radiometric observations made aboard the R.H. Brown. Mean cloud conditions are found to moderate the top of atmosphere (TOA) radiative forcing by a factor of ˜3 compared to clear-sky calculations, but atmospheric absorption by aerosol is not strongly affected by clouds in this study. The regional aerosol effect at the TOA ("climate forcing") of -3 Wm-2 is comparable in magnitude, but of opposite

  17. Single radial immunodiffusion analysis for quantitation of colostral immunoglobulin concentration.

    PubMed

    Fleenor, W A; Stott, G H

    1981-05-01

    Relative accuracy of the single radial immunodiffusion technique to measure immunoglobulin concentrations of colostral preparations (whey, whole, or fat-free) has been assessed. Fresh colostrum samples were analyzed for major constituents. Gammaglobulin as a standard was compared to total immunoglobulin concentration derived from single radial immunodiffusion analysis of colostral preparations with no differences except between standard and whey. Differences were in part from either enhancement or interference of immunoglobulin diffusion by colostral constituents. Removal of casein and fat during whey preparations caused a concentrating effect upon immunoglobulin constituents resulting in exaggerated precipitin rings. Whey has produced unreliable results: therefore, whole colostrum is recommended for single radial immunodiffusion analysis.

  18. Consistency check for radial distribution functions of water

    NASA Astrophysics Data System (ADS)

    Lie, George C.

    1986-12-01

    From a relation between the thermal compressibility and radial distribution function, it is shown that the accuracy of the generally accepted Narten and Levy's experimental radial distribution functions (RDFs) for water is very low, compared with newer experimental results. The most recent experimental RDFs obtained by Soper and Phillips not only pass the consistency check derived, but also have the best overall agreement with the simulated results of Lie and Clementi.

  19. Turbine with radial acting seal

    DOEpatents

    Eng, Darryl S; Ebert, Todd A

    2016-11-22

    A floating brush seal in a rim cavity of a turbine in a gas turbine engine, where the floating brush seal includes a seal holder in which the floating brush seal floats, and a expandable seal that fits within two radial extending seal slots that maintains a seal with radial displacement of the floating brush seal and the seal holder.

  20. Radial flow heat exchanger

    DOEpatents

    Valenzuela, Javier

    2001-01-01

    A radial flow heat exchanger (20) having a plurality of first passages (24) for transporting a first fluid (25) and a plurality of second passages (26) for transporting a second fluid (27). The first and second passages are arranged in stacked, alternating relationship, are separated from one another by relatively thin plates (30) and (32), and surround a central axis (22). The thickness of the first and second passages are selected so that the first and second fluids, respectively, are transported with laminar flow through the passages. To enhance thermal energy transfer between first and second passages, the latter are arranged so each first passage is in thermal communication with an associated second passage along substantially its entire length, and vice versa with respect to the second passages. The heat exchangers may be stacked to achieve a modular heat exchange assembly (300). Certain heat exchangers in the assembly may be designed slightly differently than other heat exchangers to address changes in fluid properties during transport through the heat exchanger, so as to enhance overall thermal effectiveness of the assembly.

  1. A Cubic Radial Basis Function in the MLPG Method for Beam Problems

    NASA Technical Reports Server (NTRS)

    Raju, I. S.; Phillips, D. R.

    2002-01-01

    A non-compactly supported cubic radial basis function implementation of the MLPG method for beam problems is presented. The evaluation of the derivatives of the shape functions obtained from the radial basis function interpolation is much simpler than the evaluation of the moving least squares shape function derivatives. The radial basis MLPG yields results as accurate or better than those obtained by the conventional MLPG method for problems with discontinuous and other complex loading conditions.

  2. Pressure anisotropy and radial stress balance in the Jovian neutral sheet

    NASA Technical Reports Server (NTRS)

    Paranicas, C. P.; Mauk, B. H.; Krimigis, S. M.

    1991-01-01

    By examining particle and magnetic field data from the Voyager 1 and 2 spacecraft, signatures were found indicating that the (greater than about 28 keV) particle pressure parallel to the magnetic field is greater than the pressure perpendicular to the field within the nightside neutral sheet (three nightside neutral sheet crossings, with favorable experimental conditions, were used). By incorporating the pressure anisotropy into the calculation of radial forces within the hightside neutral sheet, it is found that (1) force balance is approximately achieved and (2) the anisotropy force term provides the largest contribution of the other particle forces considered (pressure gradients and the corotation centrifugal force). With regard to the problem of understanding the balance of radial forces within the dayside neutral sheet (McNutt, 1984; Mauk and Krimigis, 1987), the nightside pressure anisotropy force is larger than the dayside pressure gradient forces at equivalent radial distances; however, a full accounting of the dayside regions remains to be achieved.

  3. An Ensemble Three-Dimensional Constrained Variational Analysis Method to Derive Large-Scale Forcing Data for Single-Column Models

    NASA Astrophysics Data System (ADS)

    Tang, Shuaiqi

    Atmospheric vertical velocities and advective tendencies are essential as large-scale forcing data to drive single-column models (SCM), cloud-resolving models (CRM) and large-eddy simulations (LES). They cannot be directly measured or easily calculated with great accuracy from field measurements. In the Atmospheric Radiation Measurement (ARM) program, a constrained variational algorithm (1DCVA) has been used to derive large-scale forcing data over a sounding network domain with the aid of flux measurements at the surface and top of the atmosphere (TOA). We extend the 1DCVA algorithm into three dimensions (3DCVA) along with other improvements to calculate gridded large-scale forcing data. We also introduce an ensemble framework using different background data, error covariance matrices and constraint variables to quantify the uncertainties of the large-scale forcing data. The results of sensitivity study show that the derived forcing data and SCM simulated clouds are more sensitive to the background data than to the error covariance matrices and constraint variables, while horizontal moisture advection has relatively large sensitivities to the precipitation, the dominate constraint variable. Using a mid-latitude cyclone case study in March 3rd, 2000 at the ARM Southern Great Plains (SGP) site, we investigate the spatial distribution of diabatic heating sources (Q1) and moisture sinks (Q2), and show that they are consistent with the satellite clouds and intuitive structure of the mid-latitude cyclone. We also evaluate the Q1 and Q2 in analysis/reanalysis, finding that the regional analysis/reanalysis all tend to underestimate the sub-grid scale upward transport of moist static energy in the lower troposphere. With the uncertainties from large-scale forcing data and observation specified, we compare SCM results and observations and find that models have large biases on cloud properties which could not be fully explained by the uncertainty from the large-scale forcing

  4. Accuracy of Quantum Mechanically Derived Force-Fields Parameterized from Dispersion-Corrected DFT Data: The Benzene Dimer as a Prototype for Aromatic Interactions.

    PubMed

    Prampolini, Giacomo; Livotto, Paolo Roberto; Cacelli, Ivo

    2015-11-10

    A multilevel approach is presented to assess the ability of several popular dispersion corrected density functionals (M06-2X, CAM-B3LYP-D3, BLYP-D3, and B3LYP-D3) to reliably describe two-body interaction potential energy surfaces (IPESs). To this end, the automated Picky procedure ( Cacelli et al. J. Comput. Chem. 2012 , 33 , 1055 ) was exploited, which consists in parametrizing specific intermolecular force fields through an iterative approach, based on the comparison with quantum mechanical data. For each of the tested functionals, the resulting force field was employed in classical Monte Carlo and Molecular Dynamics simulations, performed on systems of up to 1000 molecules in ambient conditions, to calculate a number of condensed phase properties. The comparison of the resulting structural and dynamic properties with experimental data allows us to assess the quality of each IPES and, consequently, even the quality of the DFT functionals. The methodology is tested on the benzene dimer, commonly used as a benchmark molecule, a prototype of aromatic interactions. The best results were obtained with the CAM-B3LYP-D3 functional. Besides assessing the reliability of DFT functionals in describing aromatic IPESs, this work provides a further step toward a robust protocol for the derivation of sound force field parameters from quantum mechanical data. This method can be relevant in all those cases where standard force fields fail in giving accurate predictions.

  5. Cirrus cloud radiative forcing at the top of atmosphere using the nighttime global distribution with the microphysical parameters derived from AVHRR

    NASA Astrophysics Data System (ADS)

    Katagiri, Shuichiro; Sekiguchi, Miho; Hayasaka, Tadahiro; Nakajima, Teruyuki

    2013-05-01

    The radiative effect of cirrus clouds is particularly ambiguous in the climate research. We calculated the global cirrus cloud radiative forcing (CRFci) distributions at the top of the atmosphere (TOA) using the cloud microphysical parameters of effective radius (Re), optical thickness (COT) and the cloud top temperature (CTT) derived from AVHRR nighttime data. The results indicate that cirrus clouds warm the atmosphere, and in particular produce a large warming effect in the tropics. We also computed the dependence of radiative forcing on the effective radius of cloud particles, the optical thickness of the cloud, and the cloud-top temperature (CTT) and determined that cooling effects occur with clouds when their optical thickness is greater than 4.0˜4.5 with a cloud top temperature of 220K and 2.5˜3.0 with a cloud top temperature of 235K. Cloud radiative forcing in April 1987 (El Niño year) and April 1990 (neutral year) were computed, and found that a larger amount of cirrus clouds appeared in the tropics off Peru in 1987 than in 1990. But the globally averaged net cloud radiative forcing was smaller by 0.55W/m2 in 1987 than in 1990. Consequently, the temperature distribution of the oceans has a global effect on atmospheric warming and cooling.

  6. On deriving the Maxwell stress tensor method for calculating the optical force and torque on an object in harmonic electromagnetic fields

    NASA Astrophysics Data System (ADS)

    Ye, Qian; Lin, Haoze

    2017-07-01

    Though extensively used in calculating optical force and torque acting on a material object illuminated by laser, the Maxwell stress tensor (MST) method follows the electromagnetic linear and angular momentum balance that is usually derived in most textbooks for a continuous volume charge distribution in free space, if not resorting to the application of Noether’s theorem in electrodynamics. To cast the conservation laws into a physically appealing form involving the current densities of linear and angular momentum, on which the MST method is based, the divergence theorem is employed to transform a volume integral into a surface integral. When a material object of finite volume is put into the field, it brings about a discontinuity of field across its surface, due to the presence of induced surface charge and surface current. Ambiguity arises among students in whether the divergence theorem can still be directly used without any justification. By taking into account the effect of the induced surface charge and current, we present a simple pedagogical derivation for the MST method for calculating the optical force and torque on an object immersed in monochromatic optical field, without resorting to Noether’s theorem. Although the results turn out to be identical to those given in the standard textbooks, our derivation avoids the direct use of the divergence theorem on a discontinuous function.

  7. Radially sandwiched cylindrical piezoelectric transducer

    NASA Astrophysics Data System (ADS)

    Lin, Shuyu; Fu, Zhiqiang; Zhang, Xiaoli; Wang, Yong; Hu, Jing

    2013-01-01

    A new type of radially sandwiched piezoelectric short cylindrical transducer is developed and its radial vibration is studied. The transducer is composed of a solid metal disk, a radially polarized piezoelectric ceramic short tube and a metal tube. The radial vibrations of the solid metal disk, the radially polarized piezoelectric tube and the metal tube are analyzed and their electromechanical equivalent circuits are introduced. Based on the mechanical boundary conditions among the metal disk, the piezoelectric tube and the metal tube, a three-port electromechanical equivalent circuit for the radially sandwiched transducer is obtained and the frequency equation is given. The theoretical relationship of the resonance and anti-resonance frequencies and the effective electromechanical coupling coefficient with the geometrical dimensions is analyzed. The radial vibration of the sandwiched transducer is simulated by using two different numerical methods. It is shown that the analytical resonance and anti-resonance frequencies are in good agreement with the numerically simulated results. The transducer is expected to be used in piezoelectric resonators, actuators and ultrasonic radiators in ultrasonic and underwater sound applications.

  8. A data-derived forecast model of surface circulation based on statistical forcing-response decomposition techniques

    NASA Astrophysics Data System (ADS)

    Kim, Sung Yong

    2016-04-01

    This paper presents a data-derived surface current forecast model based on statistical decomposition techniques [Kim et al 2010] on the observations of high-frequency radar-derived surface currents, local winds, and sea surface height anomalies (SSHA) off southern San Diego. The regional surface circulation mainly consists of tide-, wind-, and low-frequency pressure gradient-coherent components, which leads us to use tidal harmonic analysis, response functions using wind stress and pressure gradients, autoregressive analysis for residual components in the forecast model. These basis functions have been consecutively added, and the performance of corresponding forecast models is evaluated.

  9. Local nonlinear rf forces in inhomogeneous magnetized plasmas

    SciTech Connect

    Chen, Jiale; Gao, Zhe

    2014-06-15

    The local nonlinear forces induced by radio frequency (rf) waves are derived in inhomogeneous magnetized plasmas, where the inhomogeneity exists in the rf fields, in the static magnetic field as well as in the equilibrium density and temperature. The local parallel force is completely resonant, but a novel component dependent on those inhomogeneities is obtained as the result of the inhomogeneous transport of parallel resonant-absorbed momentum by the nonlinear perpendicular drift flux. In the local poloidal force, the component induced by the inhomogeneity of rf power absorption is also confirmed and it can be recognized as the residual effect from the incomplete cancellation between the rate of the diamagnetic poloidal momentum gain and the Lorentz force due to the radial diffusion-like flux. The compact expression for radial force is also obtained for the first time, whose nonresonant component is expressed as the sum of the ponderomotive force on particles and the gradients of the nonresonant perpendicular pressure and of the nonresonant momentum flux due to the finite temperature effect. Numerical calculations in a 1-D slab model show that the resonant component dependent on the inhomogeneities may be significant when the ion absorption dominates the resonant wave-particle interaction. A quantitative estimation shows that the novel component in the parallel force is important to understand the experiments of the ion-cyclotron-frequency mode-conversion flow drive.

  10. Large atmospheric shortwave radiative forcing by Mediterranean aerosols derived from simultaneous ground-based and spaceborne observations and dependence on the aerosol type and single scattering albedo

    NASA Astrophysics Data System (ADS)

    di Biagio, Claudia; di Sarra, Alcide; Meloni, Daniela

    2010-05-01

    Aerosol optical properties and shortwave irradiance measurements at the island of Lampedusa (central Mediterranean) during 2004-2007 are combined with Clouds and the Earth's Radiant Energy System observations of the outgoing shortwave flux at the top of the atmosphere (TOA). The measurements are used to estimate the surface (FES), the top of the atmosphere (FETOA), and the atmospheric (FEATM) shortwave aerosol forcing efficiencies for solar zenith angle (θ) between 15° and 55° for desert dust (DD), urban/industrial-biomass burning aerosols (UI-BB), and mixed aerosols (MA). The forcing efficiency at the different atmospheric levels is derived by applying the direct method, that is, as the derivative of the shortwave net flux versus the aerosol optical depth at fixed θ. The diurnal average forcing efficiency at the surface/TOA at the equinox is (-68.9 ± 4.0)/(-45.5 ± 5.4) W m-2 for DD, (-59.0 ± 4.3)/(-19.2 ± 3.3) W m-2 for UI-BB, and (-94.9 ± 5.1)/(-36.2 ± 1.7) W m-2 for MA. The diurnal average atmospheric radiative forcing at the equinox is (+7.3 ± 2.5) W m-2 for DD, (+8.4 ± 1.9) W m-2 for UI-BB, and (+8.2 ± 1.9) W m-2 for MA, suggesting that the mean atmospheric forcing is almost independent of the aerosol type. The largest values of the atmospheric forcing may reach +35 W m-2 for DD, +23 W m-2 for UI-BB, and +34 W m-2 for MA. FETOA is calculated for MA and 25° ≤ θ ≤ 35° for three classes of single scattering albedo (0.7 ≤ ω < 0.8, 0.8 ≤ ω < 0.9, and 0.9 ≤ ω ≤ 1) at 415.6 and 868.7 nm: FETOA increases, in absolute value, for increasing ω. A 0.1 increment in ω determines an increase in FETOA by 10-20 W m-2.

  11. Analysis of Calcium Transients and Uniaxial Contraction Force in Single Human Embryonic Stem Cell-Derived Cardiomyocytes on Microstructured Elastic Substrate with Spatially Controlled Surface Chemistries.

    PubMed

    Grespan, Eleonora; Martewicz, Sebastian; Serena, Elena; Le Houerou, Vincent; Rühe, Jürgen; Elvassore, Nicola

    2016-11-22

    The mechanical activity of cardiomyocytes is the result of a process called excitation-contraction coupling (ECC). A membrane depolarization wave induces a transient cytosolic calcium concentration increase that triggers activation of calcium-sensitive contractile proteins, leading to cell contraction and force generation. An experimental setup capable of acquiring simultaneously all ECC features would have an enormous impact on cardiac drug development and disease study. In this work, we develop a microengineered elastomeric substrate with tailor-made surface chemistry to measure simultaneously the uniaxial contraction force and the calcium transients generated by single human cardiomyocytes in vitro. Microreplication followed by photocuring is used to generate an array consisting of elastomeric micropillars. A second photochemical process is employed to spatially control the surface chemistry of the elastomeric pillar. As result, human embryonic stem cell-derived cardiomyocytes (hESC-CMs) can be confined in rectangular cell-adhesive areas, which induce cell elongation and promote suspended cell anchoring between two adjacent micropillars. In this end-to-end conformation, confocal fluorescence microscopy allows simultaneous detection of calcium transients and micropillar deflection induced by a single-cell uniaxial contraction force. Computational finite elements modeling (FEM) and 3D reconstruction of the cell-pillar interface allow force quantification. The platform is used to follow calcium dynamics and contraction force evolution in hESC-CMs cultures over the course of several weeks. Our results show how a biomaterial-based platform can be a versatile tool for in vitro assaying of cardiac functional properties of single-cell human cardiomyocytes, with applications in both in vitro developmental studies and drug screening on cardiac cultures.

  12. Black carbon radiative forcing derived from AERONET measurements and models over an urban location in the southeastern Iberian Peninsula

    NASA Astrophysics Data System (ADS)

    Valenzuela, A.; Arola, A.; Antón, M.; Quirantes, A.; Alados-Arboledas, L.

    2017-07-01

    This paper provides an account of observed variations in Black carbon (BC) aerosol concentrations and their induced radiative forcing for the first time over Granada a measurement site in Southeastern Iberian Peninsula. Column-integrated BC concentrations were retrieved for the period 2005-2012. Monthly averages of BC concentrations (± one standard deviation) ranged from higher values in January and December with 4.0 ± 2.5 and 4 ± 3 mg/m2, respectively, to lower values in July and August with 1.6 ± 1.2 and 2.0 ± 0.5 mg/m2, respectively. This reduction is not only observed in the average values, but also in the median, third and first quartiles. The average BC concentration in winter (3.8 ± 0.6 mg/m2) was substantially higher than in summer (1.9 ± 0.3 mg/m2), being the eight-year average of 2.9 ± 0.9 mg/m2. The reduction in the use of fossil fuels during the economic crisis contributed significantly to reduced atmospheric loadings of BC. According to our analysis this situation persisted until 2010. BC concentration values were analyzed in terms of air mass influence using cluster analysis. BC concentrations for cluster 1 (local and regional areas) showed high correlations with air masses frequency in winter and autumn. In these seasons BC sources were related to the intense road traffic and increased BC emissions from domestic heating. High BC concentrations were found in autumn just when air mass frequencies for cluster 3 (Mediterranean region) were more elevated, suggesting that air masses coming from that area transport biomass burning particles towards Granada. BC aerosol optical properties were retrieved from BC fraction using aerosol AERONET size volume distribution and Mie theory. A radiative transfer model (SBDART) was used to estimate the aerosol radiative forcing separately for composite aerosol (total aerosols) and exclusively for BC aerosols. The mean radiative forcing for composite aerosol was + 23 ± 6 W/m2 (heating rate of + 0.21 ± 0.06 K

  13. Coherent anti-phasing between solar forcing and tropical Pacific climate over the past millennium: derivation and implications

    NASA Astrophysics Data System (ADS)

    Emile-Geay, J.; Cobb, K.; Mann, M. E.; Wittenberg, A. T.

    2011-12-01

    Using a compilation of the most recent, high-resolution proxy data from the tropics, and a state-of-the-art climate reconstruction technique (RegEM iTTLS; Emile-Geay et al, submitted), we reconstruct sea-surface temperature (SST) in the central equatorial Pacific (NINO3.4 region) over the past millennium. Using frozen network experiments and pseudoproxy validation, the reconstruction is found skillful back to 1150 C.E., with inevitable amplitude reduction before 1500 C.E. due to the paucity of proxy predictors. Despite this caveat, wavelet coherency analysis reveals a marked anticorrelation between solar forcing (as estimated from cosmogenic isotope concentrations; Bard et al., 2007; Steinhilber et al., 2009) and the reconstructed NINO3.4 in the ~sim205-year spectral range (DeVries cycle). The phase angle between both signals is 156 ± 33o in this range, indicating that periods of high solar irradiance coincide with cool conditions in the NINO3.4 region, with time lag of 14 ± 19 years. We find this result robust to the reconstruction method, estimate of solar forcing, or analysis method used to estimate the phasing. We then discuss the implication of this result for the response of tropical Pacific climate to radiative forcing. While the anti-phasing seems to favor the ``ocean dynamical thermostat'' hypothesis of Clement et al [1996], this feedback appears subdued in most IPCC-class coupled general circulation models (CGCMs), where it is almost completely compensated by changes in the Pacific trade winds, linked to changes in the vertical structures of atmospheric moisture and temperature (Knutson & Manabe 1995; Held & Soden 2006; Vecchi et al. 2006). If the reconstruction is correct that past NINO3.4 SSTs have varied out of phase with solar irradiance on bicentennial scales, this would pose a new challenge both for CGCM simulations and for our understanding of the equatorial Pacific response to radiative forcing Clement, A. C., Seager, R., Cane, M. A., and Zebiak

  14. Analysis of an internally radially cracked ring segment subject to three-point radial loading

    NASA Technical Reports Server (NTRS)

    Gross, B.; Srawley, J. E.

    1983-01-01

    The boundary collocation method was used to generate Mode 1 stress intensity and crack mouth opening displacement coefficients for externally radially cracked ring segments subjected to three point radial loading. Numerical results were obtained for ring segment outer-to-inner radius ratios (R sub o/R sub i) ranging from 1.10 to 2.50 and crack length to segment width ratios (a/W) ranging from 0.1 to 0.8. Stress intensity and crack mouth displacement coefficients were found to depend on the ratios R sub o/R sub i and a/W as well as the included angle between the directions of the reaction forces. Previously announced in STAR as N83-35413

  15. Analysis of an Externally Radially Cracked Ring Segment Subject to Three-Point Radial Loading

    NASA Technical Reports Server (NTRS)

    Gross, B.; Srawlwy, J. E.; Shannon, J. L., Jr.

    1983-01-01

    The boundary collocation method was used to generate Mode 1 stress intensity and crack mouth opening displacement coefficients for externally radially cracked ring segments subjected to three point radial loading. Numerical results were obtained for ring segment outer-to-inner radius ratios (R sub o/R sub i) ranging from 1.10 to 2.50 and crack length to segment width ratios (a/W) ranging from 0.1 to 0.8. Stress intensity and crack mouth displacement coefficients were found to depend on the ratios R sub o/R sub i and a/W as well as the included angle between the directions of the reaction forces.

  16. Radial Clearance of Antifriction Bearings,

    DTIC Science & Technology

    The article concerns in detail the radial clearance of different antifriction bearings which belong to important parameters which influence the...longevity of the bearing to a certain extent. The effect of the influence of assembly and the wear on the radial clearance of different bearings, the...antifriction bearings operate and their respect in clearance and assembly can contribute substantially to decreasing the daily disproportionate bearing consumption for the repair and maintenance of different machines. (Author)

  17. Controlled, blinded force platform analysis of the effect of intraarticular injection of autologous adipose-derived mesenchymal stem cells associated to PRGF-Endoret in osteoarthritic dogs

    PubMed Central

    2013-01-01

    Background Adipose-derived mesenchymal stem cell (ADMSC) therapy in regenerative medicine is a rapidly growing area of research and is currently also being used to treat osteoarthritis (OA). Force platform analysis has been consistently used to verify the efficacy of different therapeutic strategies for the treatment of OA in dogs, but never with AD-MSC. The aim of this study was to use a force platform to measure the efficacy of intraarticular ADMSC administration for limb function improvement in dogs with severe OA. Results Eight lame dogs with severe hip OA and a control group of 5 sound dogs were used for this study. Results were statistically analyzed to detect a significant increase in peak vertical force (PVF) and vertical impulse (VI) in treated dogs. Mean values of PVF and VI were significantly improved after treatment of the OA groups, reaching 53.02% and 14.84% of body weight, respectively, at day 180, compared with only 43.56% and 12.16% at day 0. Conclusion This study objectively demonstrated that intraarticular ADMSC therapy resulted in reduced lameness due to OA. PMID:23819757

  18. Quantification of platelets and platelet derived growth factors from platelet-rich-plasma (PRP) prepared at different centrifugal force (g) and time.

    PubMed

    Arora, Satyam; Doda, Veena; Kotwal, Urvershi; Dogra, Mitu

    2016-02-01

    Platelet derived biomaterials represent a key source of cytokines and growth factors extensively used for tissue regeneration; wound healing and tissue repair. Our study was to quantify platelets and growth factors released by PRP when prepared at different centrifugal force (g) and time. Our study was approved by the institutional ethical committee. One hundred millilitres of whole blood (WB) was collected in bag with CPDA as the anticoagulant(AC); (14 mL for 100 mL WB ratio). Nine aliquots of 10 mL each were made from the bag and set of three aliquots were made a group. PRP was prepared at varying centrifugal force (group A: -110 g, group B: -208 g & group C: -440 g) & time (1: -5 min, 2: -10 min & 3: -20 min). Contents of each PRP prepared were analysed. Commercial sandwich ELISA kits were used to quantify the concentrations of CD62P (Diaclone SAS; France), Platelet derived growth factors-AB (Qayee-Bio; China), transforming growth factor-β1 (DRG; Germany) and vascular endothelial growth factor (Boster Immuno Leader; USA) released in each PRP prepared. Eight volunteers were enrolled in the study (24-30 years). The baseline blood counts of all the volunteers were comparable (p ≥ 0.05). Mean ± SD of platelet yield of all nine groups ranged from 17.2 ± 4.2% to 78.7 ± 5.7%. Each PRP was activated with calcified thromboplastin to quantify the growth factors released by them. Significantly higher (p < 0.05) transforming growth factor-β1 and vascular endothelial growth factor were released compared to the baseline. Our study highlights the variation in both force (g) and time results in changes at cellular level and growth factor concentrations. Copyright © 2016 Elsevier Ltd. All rights reserved.

  19. Case study of spatial and temporal variability of snow cover, grain size, albedo and radiative forcing in the Sierra Nevada and Rocky Mountain snowpack derived from imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Seidel, Felix C.; Rittger, Karl; McKenzie Skiles, S.; Molotch, Noah P.; Painter, Thomas H.

    2016-06-01

    Quantifying the spatial distribution and temporal change in mountain snow cover, microphysical and optical properties is important to improve our understanding of the local energy balance and the related snowmelt and hydrological processes. In this paper, we analyze changes of snow cover, optical-equivalent snow grain size (radius), snow albedo and radiative forcing by light-absorbing impurities in snow and ice (LAISI) with respect to terrain elevation and aspect at multiple dates during the snowmelt period. These snow properties are derived from the NASA/JPL Airborne Visible/Infrared Imaging Spectrometer (AVIRIS) data from 2009 in California's Sierra Nevada and from 2011 in Colorado's Rocky Mountains, USA. Our results show a linearly decreasing snow cover during the ablation period in May and June in the Rocky Mountains and a snowfall-driven change in snow cover in the Sierra Nevada between February and May. At the same time, the snow grain size is increasing primarily at higher elevations and north-facing slopes from 200 microns to 800 microns on average. We find that intense snowmelt renders the mean grain size almost invariant with respect to elevation and aspect. Our results confirm the inverse relationship between snow albedo and grain size, as well as between snow albedo and radiative forcing by LAISI. At both study sites, the mean snow albedo value decreases from approximately 0.7 to 0.5 during the ablation period. The mean snow grain size increased from approximately 150 to 650 microns. The mean radiative forcing increases from 20 W m-2 up to 200 W m-2 during the ablation period. The variability of snow albedo and grain size decreases in general with the progression of the ablation period. The spatial variability of the snow albedo and grain size decreases through the melt season while the spatial variability of radiative forcing remains constant.

  20. Generation and propagation of a vector cosine-Gaussian correlated beam with radial polarization.

    PubMed

    Zhu, Shijun; Chen, Yahong; Wang, Jing; Wang, Haiyan; Li, Zhenhua; Cai, Yangjian

    2015-12-28

    Scalar cosine-Gaussian-correlated Schell-model (CGCSM) beams of circular or rectangular symmetry were introduced just recently. In this paper, a new kind of partially coherent vector beam named vector CGCSM beam with radial polarization (i.e., radially polarized CGCSM beam) is introduced. The realizability conditions for a radially polarized CGCSM source and the beam condition for radiation generated by such source are derived. The statistical properties, such as the average intensity, the degree of coherence, the degree of polarization and the state of polarization, of a radially polarized CGCSM beam focused by a thin lens are analyzed in detail. It is found that the statistical properties of a radially polarized CGCSM beam are quite different from those of a conventional radial polarized partially coherent beam with Gaussian correlated Schell-model function. Furthermore, we first report experimental generation of a radially polarized CGCSM beam and measure its focusing properties. Our experimental results are consistent with the theoretical predictions.

  1. Magnetically suspended centrifugal blood pump with a radial magnetic driver.

    PubMed

    Hoshi, Hideo; Katakoa, Kiroyuki; Ohuchi, Katsuhiro; Asama, Jun-ichi; Shinshi, Tadahiko; Shimokohbe, Akira; Takatani, Setsuo

    2005-01-01

    A new magnetic bearing has been designed to achieve a low electronic power requirement and high stiffness. The magnetic bearing consists of 1) radial passive forces between the permanent magnet ring mounted inside the impeller rotor and the electromagnet core materials in the pump casing and 2) radial active forces generated by the electromagnets using the two gap sensor signals. The magnetic bearing was assembled into a centrifugal rotary blood pump (CRBP) driven with a radial, magnetic coupled driver. The impeller vane shape was designed based upon the computational fluid dynamic simulation. The diameter and height of the CRBP were 75 mm and 50 mm, respectively. The magnetic bearing system required the power of 1.0-1.4 W. The radial impeller movement was controlled to within +/- 10 microm. High stiffness in the noncontrolled axes, Z, phi, and theta, was obtained by the passive magnetic forces. The pump flow of 5 L/min against 100 mm Hg head pressure was obtained at 1,800 rpm with the electrical to hydraulic efficiency being greater than 15%. The Normalized Index of Hemolysis (NIH) of the magnetic bearing CRBP was one fifth of the BioPump BP-80 and one half of the NIKKISO HPM-15 after 4 hours. The newly designed magnetic bearing with two degrees of freedom control in combination with optimized impeller vane was successful in achieving an excellent hemolytic performance in comparison with the clinical centrifugal blood pumps.

  2. Quartic force field-derived vibrational frequencies and spectroscopic constants for the isomeric pair SNO and OSN and isotopologues

    SciTech Connect

    Fortenberry, Ryan C.; Francisco, Joseph S.

    2015-08-28

    The SNO and OSN radical isomers are likely to be of significance in atmospheric and astrochemistry, but very little is known about their gas phase spectroscopic properties. State-of-the-art ab initio composite quartic force fields are employed to analyze the rovibrational features for both systems. Comparison to condensed-phase experimental data for SNO has shown that the 1566.4 cm{sup −1} ν{sub 1} N–O stretch is indeed exceptionally bright and likely located in this vicinity for subsequent gas phase experimental analysis. The OSN ν{sub 1} at 1209.4 cm{sup −1} is better described as the antisymmetric stretch in this molecule and is also quite bright. The full vibrational, rotational, and rovibrational data are provided for SNO and OSN and their single {sup 15}N, {sup 18}O, and {sup 34}S isotopic substitutions in order to give a more complete picture as to the chemical physics of these molecules.

  3. The impact of wave-induced Coriolis-Stokes forcing on satellite-derived ocean surface currents

    NASA Astrophysics Data System (ADS)

    Hui, Zhenli; Xu, Yongsheng

    2016-01-01

    Ocean surface currents estimated from the satellite data consist of two terms: Ekman currents from the wind stress and geostrophic currents from the sea surface height (SSH). But the classical Ekman model does not consider the wave effects. By taking the wave-induced Coriolis-Stokes forcing into account, the impact of waves (primarily the Stokes drift) on ocean surface currents is investigated and the wave-modified currents are formed. The products are validated by comparing with OSCAR currents and Lagrangian drifter velocity. The result shows that our products with the Stokes drift are better adapted to the in situ Lagrangian drifter currents. Especially in the Southern Ocean region (40°S-65°S), 90% (91%) of the zonal (meridional) currents have been improved compared with currents that do not include Stokes drift. The correlation (RMSE) in the Southern Ocean has also increased (decreased) from 0.78 (13) to 0.81 (10.99) for the zonal component and 0.76 (10.87) to 0.79 (10.09) for the meridional component. This finding provides the evidence that waves indeed play an important role in the ocean circulation, and need to be represented in numerical simulations of the global ocean circulation. This article was corrected on 10 FEB 2016. See the end of the full text for details.

  4. Clinical usefulness of the second peak of radial systolic blood pressure for estimation of aortic systolic blood pressure.

    PubMed

    Kohara, K; Tabara, Y; Tomita, H; Nagai, T; Igase, M; Miki, T

    2009-08-01

    Central aortic blood pressure (BP), obtained from radial arterial waveform using the transfer function method (TFM), has been shown to have prognostic value independently of brachial BP. In this study, the relationship between peripheral systolic BP (SBP) and aortic SBP was evaluated. We further investigated whether TFM-derived aortic SBP can be estimated by information obtained from the radial waveform. The radial waveform was analysed to obtain the first peak of radial SBP (SBP1), second peak of radial SBP (SBP2), radial augmentation index (AI) (radial (SBP2-DBP)/(SBP1-DBP) x 100 and aortic SBP and AI using TFM in 233 subjects in the supine position. Measurements were repeated after changing position to the prone position. The constructed equation was validated in 149 community residents with different backgrounds. Radial SBP2 was closer to TFM-derived aortic SBP compared with brachial SBP. TFM-derived aortic SBP was approximated by the equation: aortic SBP=18.9-radial SBP2-0.03 x HR-0.214 x radial AI (r2=0.992). The equation was also applicable to predicting aortic SBP in the prone position as well as in different populations (mean difference between predicted aortic SBP and TFM-derived aortic SBP: -0.01+/-1.34 and 1.05+/-1.47 mm Hg, respectively). Radial arterial waveform analysis can be used for estimation of TFM-derived aortic SBP.

  5. Stellar Mass Radial Profiles of Pan-STARRS MDS Galaxies

    NASA Astrophysics Data System (ADS)

    Zheng, Zheng; Thilker, D. A.; Heckman, T. M.

    2013-01-01

    Six-band (ugrizy) surface brightness radial profiles are derived for a sample of 48 late-type face-on non-interacting nearby galaxies using the Pan-STARRS Medium Deep Survey stack imaging (grizy) and the CFHT deep u-band imaging data. The surface brightnesses are measured down to ~ 29-30 ABmag/arcsec^2. The SB radial profiles are then fed into the advanced SED fitting software MAGPHYS (da Cunha et al. 2008) to derive radial profiles of stellar mass surface density as well as other parameters, such as metallicity and star formation history. The output stellar mass surface density profiles can be classified into three types (single exponential, down-bending, and up-bending), which is consistent with the results of Polen & Trujillo (2006). But the up-bending profiles are more common than indicated in PT06.

  6. Local stellar kinematics from RAVE data - II. Radial metallicity gradient

    NASA Astrophysics Data System (ADS)

    Coşkunoǧlu, B.; Ak, S.; Bilir, S.; Karaali, S.; Önal, Ö.; Yaz, E.; Gilmore, G.; Seabroke, G. M.

    2012-02-01

    We investigate radial metallicity gradients for a sample of dwarf stars from the RAdial Velocity Experiment (RAVE) Data Release 3 (DR3). We select a total of approximately 17 000 F-type and G-type dwarfs, using a selection of colour, log g and uncertainty in the derived space motion, and calculate for each star a probabilistic (kinematic) population assignment to a thick or thin disc using space motion and additionally another (dynamical) assignment using stellar vertical orbital eccentricity. We additionally subsample by colour, to provide samples biased toward young thin-disc and older thin-disc stars. We derive a metallicity gradient as a function of Galactocentric radial distance, i.e. d[M/H]/dRm=-0.051 ± 0.005 dex kpc-1, for the youngest sample, F-type stars with vertical orbital eccentricities ev≤ 0.04. Samples biased toward older thin-disc stars show systematically shallower abundance gradients.

  7. Radial lean direct injection burner

    DOEpatents

    Khan, Abdul Rafey; Kraemer, Gilbert Otto; Stevenson, Christian Xavier

    2012-09-04

    A burner for use in a gas turbine engine includes a burner tube having an inlet end and an outlet end; a plurality of air passages extending axially in the burner tube configured to convey air flows from the inlet end to the outlet end; a plurality of fuel passages extending axially along the burner tube and spaced around the plurality of air passage configured to convey fuel from the inlet end to the outlet end; and a radial air swirler provided at the outlet end configured to direct the air flows radially toward the outlet end and impart swirl to the air flows. The radial air swirler includes a plurality of vanes to direct and swirl the air flows and an end plate. The end plate includes a plurality of fuel injection holes to inject the fuel radially into the swirling air flows. A method of mixing air and fuel in a burner of a gas turbine is also provided. The burner includes a burner tube including an inlet end, an outlet end, a plurality of axial air passages, and a plurality of axial fuel passages. The method includes introducing an air flow into the air passages at the inlet end; introducing a fuel into fuel passages; swirling the air flow at the outlet end; and radially injecting the fuel into the swirling air flow.

  8. Forces in General Relativity

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  9. Forces in General Relativity

    ERIC Educational Resources Information Center

    Ridgely, Charles T.

    2010-01-01

    Many textbooks dealing with general relativity do not demonstrate the derivation of forces in enough detail. The analyses presented herein demonstrate straightforward methods for computing forces by way of general relativity. Covariant divergence of the stress-energy-momentum tensor is used to derive a general expression of the force experienced…

  10. Losses in radial inflow turbines

    NASA Technical Reports Server (NTRS)

    Khalil, I. M.; Tabakoff, W.; Hamed, A.

    1976-01-01

    A study was conducted to determine experimentally and theoretically the losses in radial inflow turbine nozzles. Extensive experimental data was obtained to investigate the flow behavior in a full-scale radial turbine stator annulus. A theoretical model to predict the losses in both the vaned and vaneless regions of the nozzle was developed. In this analysis, the interaction effects between the stator and the rotor are not considered. It was found that the losses incurred due to the end wall boundary layers can be significant, especially if they are characterized by a strong crossflow. The losses estimated using the analytical study are compared with the experimentally determined values.

  11. Hydraulic radial piston pump intake porting arrangement

    SciTech Connect

    Miller, G.T.

    1987-06-16

    This patent describes a hydraulic radial piston pump having a slider block mounted on an eccentric of a rotary shaft in a hydraulic fluid supplied cavity. A piston is mounted in a cylinder disposed radially to the shaft. The piston has a flat working face at one end operating in the cylinder and a flat pad at an opposite end slidably engaged by a flat face of the slider block so as to force the piston outward on a compression stroke on shaft rotation. A yoke retains the piston to the slider block so as to retract the piston inward on an intake stroke on shaft rotation characterized by intake porting means for communicating the cavity with the working end of the piston. It comprises an intake passage extending centrally and axially through the piston from the working end to the pad resulting in an annular face at both piston ends. An elongated intake slot in the face of the slider block extends from a point continuously open to the cavity to a point that opens to the intake passage at the pad end on relative movement of the slider block during the intake stroke to just prior to the compression stroke. The annular faces at the working and pad ends of the piston having substantially equal areas to prevent hydraulic film from developing between the slider block and pad and thereby prevent their separation during compression.

  12. Radial plasma transport in Saturn's magnetosphere (Invited)

    NASA Astrophysics Data System (ADS)

    Hill, T. W.

    2010-12-01

    Radial plasma transport in the magnetosphere of Saturn, like that of Jupiter, is driven by the centrifugal force of (partial) corotation acting on internally generated plasma. A significant difference is that the internal plasma source is evidently broadly distributed throughout the inner magnetosphere of Saturn (4 < L <~12), although the neutral water vapor source is evidently tightly localized to Enceladus (L = 4). At Jupiter, by comparison, both the neutral and plasma sources are evidently largely confined to the Io plasma torus (L ~ 6-7). A possible consequence of the broadly distributed source at Saturn is the observed feature that convective outflow channels are relatively broad and slow, while the corresponding inflow channels are relatively narrow and fast. This feature is well documented by Cassini observations (primarily CAPS and MAG), and reproduced in numerical simulations (RCM) that contain a distributed plasma source, although it has not, to my knowledge, been explained by an analytical theory containing an active plasma source. Both planets exhibit strong magnetospheric modulations near the planetary spin period, probably indicating a persistent longitudinal asymmetry of the radial plasma transport process. At Jupiter such an asymmetry is readily understood as a consequence of the dramatic asymmetry of the intrinsic planetary magnetic field. This is not so at Saturn, where any such field asymmetry is known to be very modest at best. In neither case has the precise nature of the asymmetry been identified either observationally or theoretically.

  13. Reactive-infiltration instability in radial geometry

    NASA Astrophysics Data System (ADS)

    Grodzki, Piotr; Szymczak, Piotr

    2015-04-01

    A planar dissolution front propagating through a homogeneous porous matrix is unstable with respect to small variations in local permeability; regions of high permeability dissolve faster because of enhanced transport of reactants, which leads to increased rippling of the front. This phenomenon, usually referred to known as reactive-infiltration instability is an important mechanism for pattern development in geology, with a range of morphologies and scales, from cave systems running for hundreds of miles to laboratory acidization on the scale of centimeters. In general, this instability is characterized by two length scales: the diffusive length (D/v) and the reactant penetration length (v/r), where v is the Darcy velocity, D - the diffusion constant and r - the dissolution rate. If the latter scale is much smaller than the former one can adopt the so-called thin front limit, where the interface is treated as a discontinuity in porosity, with a completely dissolved phase on one side and an undissolved phase on the other. Linear stability analysis for this case has been carried out by Chadam et al. [1], and the corresponding dispersion relation shows that long wavelengths are unstable, whereas short wavelengths are stabilized by diffusion. In their derivation, Chadam et al. have considered a linear geometry with a uniform pressure gradient applied along one of the directions. However, in many cases (e.g. in the acidization techniques used in oil industry) the reactive fluids are injected through a well and thus the relevant geometry is radial rather than linear. Motivated by this, we have carried out the linear stability analysis of the reactive-infiltration problem in radial geometry, with the fluid injection at the centre of the system. We stay within the thin-front limit and derive the corresponding dispersion relation, which shows the stable regions for both the long-wavelength and short-wavelength modes, and the unstable region in between. Next, we study how

  14. Fracture behavior of lithium single crystal in the framework of (semi-)empirical force field derived from first-principles

    NASA Astrophysics Data System (ADS)

    Groh, Sébastien; Alam, Masud

    2015-06-01

    An approach to derive, from first-principles data, accurate and reliable potentials in the modified embedded-atom method in view of modeling the mechanical behavior of metals is presented in this work and applied to the optimization of a potential representative of lithium (Li). Although the theoretical background of the modified embedded-atom method was considered in this work, the proposed method is general and it can be applied to any other functional form. The main feature of the method is to introduce several path transformations in the material database that are critical for plastic and failure behavior. As part of the potential validation, path transformations different from the ones used for the parameterization procedure are considered. Applied in the case of Li, the material database was enriched with the generalized stacking fault energy curve along the  <1 1 1>  -direction on the {1 1 0}-plane, and with the traction-separation behavior of a {1 0 0}-surface. The path transformations used to enrich the material database were initially derived from first-principles calculations. For validation, the generalized stacking fault energy curves along the  <1 1 1>  -direction on the {1 1 2}- and {1 2 3}-planes were considered for plasticity, while traction-separation behavior of {1 1 0} and {1 1 1}-planes were considered for failure behavior. As part of the validation procedure, the predictions made in the MEAM framework were validated by first-principles data. The final potential accurately reproduced basic equilibrium properties, elastic constants, surface energies in agreement with first-principles predictions, and transition energy between different crystal structures. Furthermore, generalized stacking fault energy curves along the  <1 1 1>  -direction on the {1 1 0}, {1 1 2}, and {1 2 3}-planes, and tensile cohesive stress, characteristic length of fracture, and work of separation of a

  15. Analytic expressions for ULF wave radiation belt radial diffusion coefficients.

    PubMed

    Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K

    2014-03-01

    We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV-even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Analytic expressions for the radial diffusion coefficients are presentedThe coefficients do not dependent on energy or wave m valueThe electric field diffusion coefficient dominates over the magnetic.

  16. Analytic expressions for ULF wave radiation belt radial diffusion coefficients

    PubMed Central

    Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K

    2014-01-01

    We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Key Points Analytic expressions for the radial diffusion coefficients are presented The coefficients do not dependent on energy or wave m value The electric field diffusion coefficient dominates over the magnetic PMID:26167440

  17. A canonical approach to forces in molecules

    NASA Astrophysics Data System (ADS)

    Walton, Jay R.; Rivera-Rivera, Luis A.; Lucchese, Robert R.; Bevan, John W.

    2016-08-01

    In previous studies, we introduced a generalized formulation for canonical transformations and spectra to investigate the concept of canonical potentials strictly within the Born-Oppenheimer approximation. Data for the most accurate available ground electronic state pairwise intramolecular potentials in H2+, H2, HeH+, and LiH were used to rigorously establish such conclusions. Now, a canonical transformation is derived for the molecular force, F(R), with H2+ as molecular reference. These transformations are demonstrated to be inherently canonical to high accuracy but distinctly different from those corresponding to the respective potentials of H2, HeH+, and LiH. In this paper, we establish the canonical nature of the molecular force which is key to fundamental generalization of canonical approaches to molecular bonding. As further examples Mg2, benzene dimer and to water dimer are also considered within the radial limit as applications of the current methodology.

  18. A predictive model for satellite-derived phytoplankton absorption over the Louisiana shelf hypoxic zone: Effects of nutrients and physical forcing

    NASA Astrophysics Data System (ADS)

    Green, Rebecca E.; Gould, Richard W.

    2008-06-01

    We investigated environmental forcing mechanisms of phytoplankton absorption near the Mississippi River delta using multiyear satellite data. An algorithm for the phytoplankton absorption coefficient (aph) was developed from in situ measurements and applied to ocean color imagery. We employed a suite of chemical and physical forcing variables, including surface currents. For satellite-derived aph time series (2002-2004), correlation and stepwise regression analyses revealed the most important forcing variables of aph on the Louisiana shelf. Areally, Mississippi River discharge and nitrate concentration ([NO3]) were the two most important predictors of aph over the hypoxic zone (defined by its maximum extent). River discharge was important in a band stretching from the Mississippi River delta to the Louisiana-Texas border. Riverine [NO3] and wind magnitude best predicted aph in nearshore waters, and solar radiation and SST were most important farther offshore over the hypoxic zone, indicating upwelled nutrient sources to phytoplankton. A multiple linear regression model performed well in resolving seasonal and interannual aph variability in model development years (2002-2004) (mean error of 18%, over all pixels and months) and in predicting shelf-wide aph patterns in 2005 (mean error of 32%). Our results strongly suggest that in recent years, stratification and vertical mixing, in addition to riverine [NO3], play a primary role in regulating phytoplankton biomass over the hypoxic zone. As well, a springtime model experiment showed that aph over the hypoxic zone can differ by an average absolute 37% from its average scenario owing to changes solely in environmental variables other than NO3 flux.

  19. A design methodology for a magnetorheological fluid damper based on a multi-stage radial flow mode

    NASA Astrophysics Data System (ADS)

    Liao, C. R.; Zhao, D. X.; Xie, L.; Liu, Q.

    2012-08-01

    In this paper, a magnetorheological (MR) fluid damper based on a multi-stage radial flow mode is put forward, compared with traditional ones with annular damping channel which are of low magnetic field utilization and high energy consumption. The equivalent magnetic circuit model is derived, along with the relation between the magnetic induction at the working gap and the exciting current in the field coils. The finite-element software ANYSY is used to analyze the distribution of the magnetic field in the MR valve. The flow differential equation for a MR fluid in radial flow is theoretically set up, and the numerical solution is validated by means of the Herschel-Bulkley constitutive model. A MR damper was designed and fabricated in Chongqing University in accordance with the technical requirements of a railway vehicle anti-yaw damper, and the force-displacement characteristic of the damper was tested with J95-I type shock absorber test-bed. The results show that the experimental damping forces are in good agreement with the analytical ones, and the methodology is believed to help predict the damping force of a MR damper.

  20. Factors influencing the radial-tangential illusion in haptic perception.

    PubMed

    McFarland, James; Soechting, John F

    2007-04-01

    According to the radial-tangential illusion, in the horizontal plane, arm movements executed in directions radial to the trunk are sensed to be longer than movements of the same length in the orthogonal direction. It has been suggested that the illusion arises from the fact that radially directed movements are executed more slowly and require more effort. These suggestions were tested in a series of experiments, using a robotically controlled manipulandum. In all of the experiments subjects grasped the handle of the manipulandum, in some cases exploring the virtual boundary of a rectangle, while in others being guided along a rectangular contour by the robot. In a two-alternative forced choice design, subjects reported whether the rectangle was wide or narrow. In a control experiment, subjects manifested the radial-tangential illusion. Contrary to the hypothesis, the magnitude of this illusion was not altered when a resistive force was added in the tangential direction or when the ratio of movement times in the tangential and radial directions was changed. However, when the contour was explored in the counterclockwise direction, the illusion was much smaller than when it was explored in the clockwise direction. A second series of experiments, in which subjects only explored two sides (i.e., an L-shape), demonstrated that this effect arose from distortions induced by the serial ordering of the exploratory movements. The illusion was much smaller when the radial segment was explored first. We suggest that this distortion arises from the serial nature of haptic exploration, in which the length of the initial segment decreases as it is stored in working memory for subsequent comparison.

  1. Precise radial velocities of giant stars. VIII. Testing for the presence of planets with CRIRES infrared radial velocities

    NASA Astrophysics Data System (ADS)

    Trifonov, Trifon; Reffert, Sabine; Zechmeister, Mathias; Reiners, Ansgar; Quirrenbach, Andreas

    2015-10-01

    Context. We have been monitoring 373 very bright (V ≤ 6 mag) G and K giants with high precision optical Doppler spectroscopy for more than a decade at Lick Observatory. Our goal was to discover planetary companions around those stars and to better understand planet formation and evolution around intermediate-mass stars. However, in principle, long-term, g-mode nonradial stellar pulsations or rotating stellar features, such as spots, could effectively mimic a planetary signal in the radial velocity data. Aims: Our goal is to compare optical and infrared radial velocities for those stars with periodic radial velocity patterns and to test for consistency of their fitted radial velocity semiamplitudes. Thereby, we distinguish processes intrinsic to the star from orbiting companions as reason for the radial velocity periodicity observed in the optical. Methods: Stellar spectra with high spectral resolution have been taken in the H-band with the CRIRES near-infrared spectrograph at ESO's VLT for 20 stars of our Lick survey. Radial velocities are derived using many deep and stable telluric CO2 lines for precise wavelength calibration. Results: We find that the optical and near-infrared radial velocities of the giant stars in our sample are consistent. We present detailed results for eight stars in our sample previously reported to have planets or brown dwarf companions. All eight stars passed the infrared test. Conclusions: We conclude that the planet hypothesis provides the best explanation for the periodic radial velocity patterns observed for these giant stars. Based on observations collected at the European Southern Observatory, Chile, under program IDs 088.D-0132, 089.D-0186, 090.D-0155 and 091.D-0365.Appendix A is available in electronic form at http://www.aanda.org

  2. Perceived radial translation during centrifugation.

    PubMed

    Bos, Jelte E; Correia Grácio, Bruno J

    2015-01-01

    Linear acceleration generally gives rise to translation perception. Centripetal acceleration during centrifugation, however, has never been reported giving rise to a radial, inward translation perception. To study whether centrifugation can induce a radial translation perception in the absence of visual cues. To that end, we exposed 12 subjects to a centripetal acceleration with eyes closed. To avoid confounding with angular motion perception, subjects were fist rotated on-axis, and were shifted out fast and slow only after rotation sensation had vanished. They were asked for translation direction and velocity right after the shift-out, as well as after about 60 seconds of constant centrifugation. Independent of fast or slow shift-out, the vast statistically significant majority of trials yielded an inward radial translation perception, which velocity was constant after 60 seconds of constant centrifugation. We therefore conclude that during centrifugation, an inward radial translation perception does exist in humans, which perception reaches a constant, non-zero value during constant rotation, lasting for at least one minute. These results can be understood by high-pass filtering of otolith afferents to make a distinction between inertial and gravitational acceleration, followed by a mere integration over time to reach a constant velocity perception.

  3. Asymptotic screened hydrogenic radial integrals

    NASA Technical Reports Server (NTRS)

    Olsgaard, D. A.; Khan, F.; Khandelwal, G. S.

    1988-01-01

    The usefulness of the screened hydrogenic model for the transitions of the helium sequence is studied. The screened hydrogenic radial dipole integral for discrete-discrete transitions from the initial state to the final state is asymptotically expanded to the lowest order such that the final quantum number n approaches infinity. The analytical expression obtained is in terms of confluent hypergeometric functions.

  4. Effects of radial motion on interchange injections at Saturn

    NASA Astrophysics Data System (ADS)

    Paranicas, C.; Thomsen, M. F.; Achilleos, N.; Andriopoulou, M.; Badman, S. V.; Hospodarsky, G.; Jackman, C. M.; Jia, X.; Kennelly, T.; Khurana, K.; Kollmann, P.; Krupp, N.; Louarn, P.; Roussos, E.; Sergis, N.

    2016-01-01

    Charged particle injections are regularly observed in Saturn's inner magnetosphere by Cassini. They are attributed to an ongoing process of flux-tube interchange driven by the strong centrifugal force associated with Saturn's rapid rotation. Numerical simulations suggest that these interchange injections can be associated with inward flow channels, in which plasma confined to a narrow range of longitudes moves radially toward the planet, gaining energy, while ambient plasma in the adjacent regions moves more slowly outward. Most previous analyses of these events have neglected this radial motion and inferred properties of the events under the assumption that they appear instantaneously at the spacecraft's L-shell and thereafter drift azimuthally. This paper describes features of injections that can be related to their radial motion prior to observation. We use a combination of phase space density profiles and an updated version of a test-particle model to quantify properties of the injection. We are able to infer the longitudinal width of the injection, the radial travel time from its point of origin, and the starting L shell of the injection. We can also predict which energies can remain inside the channel during the radial transport. To highlight the effects of radial propagation at a finite speed, we focus on those interchange injections without extensive features of azimuthal dispersion. Injections that have traveled radially for one or more hours prior to observation would have been initiated at a different local time than that of the observation. Finally, we describe an injection where particles have drifted azimuthally into a flow channel prior to observation by Cassini.

  5. Radial elasticity of multi-walled boron nitride nanotubes

    NASA Astrophysics Data System (ADS)

    Zheng, Meng; Ke, Changhong; Bae, In-Tae; Park, Cheol; Smith, Michael W.; Jordan, Kevin

    2012-03-01

    We investigated the radial mechanical properties of multi-walled boron nitride nanotubes (MW-BNNTs) using atomic force microscopy. The employed MW-BNNTs were synthesized using pressurized vapor/condenser (PVC) methods and were dispersed in aqueous solution using ultrasonication methods with the aid of ionic surfactants. Our nanomechanical measurements reveal the elastic deformational behaviors of individual BNNTs with two to four tube walls in their transverse directions. Their effective radial elastic moduli were obtained through interpreting their measured radial deformation profiles using Hertzian contact mechanics models. Our results capture the dependences of the effective radial moduli of MW-BNNTs on both the tube outer diameter and the number of tube layers. The effective radial moduli of double-walled BNNTs are found to be several-fold higher than those of single-walled BNNTs within the same diameter range. Our work contributes directly to a complete understanding of the fundamental structural and mechanical properties of BNNTs and the pursuits of their novel structural and electronics applications.

  6. Radial elasticity of multi-walled boron nitride nanotubes

    SciTech Connect

    Michael W. Smith, Cheol Park, Meng Zheng, Changhong Ke ,In-Tae Bae, Kevin Jordan

    2012-02-01

    We investigated the radial mechanical properties of multi-walled boron nitride nanotubes (MW-BNNTs) using atomic force microscopy. The employed MW-BNNTs were synthesized using pressurized vapor/condenser (PVC) methods and were dispersed in aqueous solution using ultrasonication methods with the aid of ionic surfactants. Our nanomechanical measurements reveal the elastic deformational behaviors of individual BNNTs with two to four tube walls in their transverse directions. Their effective radial elastic moduli were obtained through interpreting their measured radial deformation profiles using Hertzian contact mechanics models. Our results capture the dependences of the effective radial moduli of MW-BNNTs on both the tube outer diameter and the number of tube layers. The effective radial moduli of double-walled BNNTs are found to be several-fold higher than those of single-walled BNNTs within the same diameter range. Our work contributes directly to a complete understanding of the fundamental structural and mechanical properties of BNNTs and the pursuits of their novel structural and electronics applications.

  7. Radial elasticity of multi-walled boron nitride nanotubes.

    PubMed

    Zheng, Meng; Ke, Changhong; Bae, In-Tae; Park, Cheol; Smith, Michael W; Jordan, Kevin

    2012-03-09

    We investigated the radial mechanical properties of multi-walled boron nitride nanotubes (MW-BNNTs) using atomic force microscopy. The employed MW-BNNTs were synthesized using pressurized vapor/condenser (PVC) methods and were dispersed in aqueous solution using ultrasonication methods with the aid of ionic surfactants. Our nanomechanical measurements reveal the elastic deformational behaviors of individual BNNTs with two to four tube walls in their transverse directions. Their effective radial elastic moduli were obtained through interpreting their measured radial deformation profiles using Hertzian contact mechanics models. Our results capture the dependences of the effective radial moduli of MW-BNNTs on both the tube outer diameter and the number of tube layers. The effective radial moduli of double-walled BNNTs are found to be several-fold higher than those of single-walled BNNTs within the same diameter range. Our work contributes directly to a complete understanding of the fundamental structural and mechanical properties of BNNTs and the pursuits of their novel structural and electronics applications.

  8. Waves in Radial Gravity Using Magnetic Fluid

    NASA Technical Reports Server (NTRS)

    Ohlsen, D. R.; Hart, J. E.; Weidman, P. D.

    1999-01-01

    Terrestrial laboratory experiments studying various fluid dynamical processes are constrained, by being in an Earth laboratory, to have a gravitational body force which is uniform and unidirectional. Therefore fluid free-surfaces are horizontal and flat. Such free surfaces must have a vertical solid boundary to keep the fluid from spreading horizontally along a gravitational potential surface. In atmospheric, oceanic, or stellar fluid flows that have a horizontal scale of about one-tenth the body radius or larger, sphericity is important in the dynamics. Further, fluids in spherical geometry can cover an entire domain without any sidewall effects, i.e. have truly periodic boundary conditions. We describe spherical body-force laboratory experiments using ferrofluid. Ferrofluids are dilute suspensions of magnetic dipoles, for example magnetite particles of order 10 nm diameter, suspended in a carrier fluid. Ferrofluids are subject to an additional body force in the presence of an applied magnetic field gradient. We use this body force to conduct laboratory experiments in spherical geometry. The present study is a laboratory technique improvement. The apparatus is cylindrically axisymmetric. A cylindrical ceramic magnet is embedded in a smooth, solid, spherical PVC ball. The geopotential field and its gradient, the body force, were made nearly spherical by careful choice of magnet height-to-diameter ratio and magnet size relative to the PVC ball size. Terrestrial gravity is eliminated from the dynamics by immersing the "planet" and its ferrofluid "ocean" in an immiscible silicone oil/freon mixture of the same density. Thus the earth gravity is removed from the dynamics of the ferrofluid/oil interface and the only dynamically active force there is the radial magnetic gravity. The entire apparatus can rotate, and waves are forced on the ferrofluid surface by exterior magnets. The biggest improvement in technique is in the wave visualization. Fluorescing dye is added to

  9. Catalog of radial velocities for northern Cepheids measured with a correlation spectrometer

    NASA Astrophysics Data System (ADS)

    Gorynya, N. A.; Irsmambetova, T. R.; Rastorgouev, A. S.; Samus, N. N.

    1992-09-01

    A catalog containing 1446 individual radial velocity values for 79 field Cepheids and three Cepheids in globular clusters, and 32 averaged radial velocities of the Cepheid Alpha UMi derived from 100 individual velocity parameters is presented. A table of gamma velocities for 30 Cepheids with sufficiently good coverage of Vr curves is included. Radial velocity observations of CE Cas A and CF Cas, which are photometric members of the open cluster NGC 7790, made it possible to estimate the radial velocity of the cluster (-78.0 km/s).

  10. The fitting of radial velocity curves using Adaptive Simulated Annealing

    NASA Astrophysics Data System (ADS)

    Iglesias-Marzoa, R.; López-Morales, M.; Arévalo Morales, M. J.

    2015-05-01

    We present a new code for fitting radial velocities of stellar binaries and exoplanets using an Adaptive Simulated Annealing (ASA) global minimisation method. ASA belongs to the family of Monte Carlo methods and its main advantages are that it only needs evaluations of the objective function, it does not rely on derivatives, and the parameters space can be periodically redefined and rescaled for individual parameters. ASA is easily scalable since the physics is concentrated in only one function and can be modified to account for more complex models. Our ASA code minimises the χ^2 function in the multidimensional parameters space to obtain the full set of parameters (P, T_p, e, ω, γ, K_1, K_2) of the keplerian radial velocity curves which best represent the observations. As a comparison we checked our results with the published solutions for several binary stars and exoplanets with available radial velocities data. We achieve good agreement within the limits imposed by the uncertainties.

  11. Generation of tunable radially polarized array beams by controllable coherence

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Zhang, Jipeng; Zhu, Shijun; Li, Zhenhua

    2017-05-01

    In this paper, a new method for converting a single radial polarization beam into an arbitrary radially polarized array (RPA) beam such as a radial or rectangular symmetry array in the focal plane by modulating a periodic correlation structure is introduced. The realizability conditions for such source and the beam condition for radiation generated by such source are derived. It is illustrated that both the amplitude and the polarization are controllable by means of initial correlation structure and coherence parameter. Furthermore, by designing the source correlation structure, a tunable NUST-shaped RPA beam is demonstrated, which can find widespread applications in micro-nano engineering. Such a method for generation of arbitrary vector array beams is useful in beam shaping and optical tweezers.

  12. Effects of chronic forced swim stress on hippocampal brain-derived neutrophic factor (BDNF) and its receptor (TrkB) immunoreactive cells in juvenile and aged rats.

    PubMed

    Badowska-Szalewska, Ewa; Spodnik, Edyta; Klejbor, Ilona; Morys, Janusz

    2010-01-01

    A type of stress stimulation and age are claimed to affect the expression of brain-derived neurotrophic factor (BDNF) and its receptor - tyrosine kinase B (TrkB) in the hippocampal regions differentially. This study aimed to explore the influence of chronic (15 min daily for 21 days) forced swim stress (FS) exposure on the BDNF and TrkB containing neurons in the hippocampal CA1, CA3 pyramidal cell layers and dentate gyrus (DG) granule cell layer in juvenile (P28) and aged (P360) rats. An immunofluorescence (-ir) method was used to detect BDNF-ir and TrkB-ir cells. Under chronic FS exposure, in the group of juvenile rats a significant decrease in the density of BDNF immunoreactive neurons was observed in CA1 and DG (P less than <0.001), unlike CA3, where it remained unaltered just as the density of TrkB-ir cells in CA1 and DG, but in CA3 the number of TrkB-ir cells was found to grow (P less than 0.05) in comparison with control groups. After chronic FS exposure of aged (P360) rats, the density of BDNF-ir and TrkB-ir cells did not decline in any of the subregions of the hippocampus. In all subfields of the hippocampus, the denseness of BDNF-positive neurons was significantly higher in P360 stressed group, compared with P28 stressed group, but the density of TrkB-ir fell more markedly in P360 than in P28. In conclusion, chronic FS stress influenced the number of BDNF and TrkB immunoreactive neurons only in juvenile animals. The age of rats tested in the chronic forced swim test was a decisive factor determining changes in the density of BDNF-ir and TrkB-ir in the hippocampal structures.

  13. The outward radial offset of neptune ring arcs

    NASA Astrophysics Data System (ADS)

    Tsui, K. H.

    2003-08-01

    It is consensus that the Neptune ring arcs are confined by the 42/43 Lindblad-corotation orbit-orbit resonant interactions with Galatea. Nevertheless, recent observations have indicated that the radial position of the arcs is off the expected resonance location by 1/3 Km outwards. Such radial offset, although very small, is unaccountable by fine tuning the restricted three-body model. In an attempt to resolve this issue, we use a restricted four-body model where the center of mass is anchored by the central body Neptune S and the primary body Triton X. Two minor bodies Galatea G and ring arc s interact with each other while orbiting under the combined XS field. In order to identify the disturbing potential, the equations of motion of s are manipulated to arrive at the energy equation in a frame centered at S with a fixed reference axis. Due to the orbital motions of X and G, the force field acting on s is non-conservative with velocity and time dependences. This non-conservative field is represented in the energy equation in two ways. First, it appears as the energy exchange terms of s with X and G on the right side of the equation. Second, it appears in the potential function on the left side of the equation in a velocity dependent term, which could be removed by going to the SX rotating frame. Rearranging the non-conservative term in the potential function and the sX energy exchange terms gives an angular momentum term of s acted on by a time derivative. This regrouped term can be expressed in terms of the usual disturbing potential V itself multiplied by a coefficient q and becomes conservative. Consequently, the disturbing potential of s read Vs = (1+q)V, and by the same token, we have VG = (1+q)V. The (1+q) factor in Vs represents the effect of the anchoring Triton X on the sG interaction. As a matter of fact, this factor can also be recovered in the restricted three-body system, but has been overlooked so far. With Vs and VG, the resonance relations are

  14. Severity grading in radial dysplasia.

    PubMed

    Vilkki, S K

    2014-11-01

    A functional scoring method to grade the usefulness and quality of the upper limbs in congenital radial dysplasia is presented. It is based on the author's examinations of 44 arms with congenital deficiency of the radius. The hand (H), wrist (W) and proximal parts (P) of the extremity are each scored from 0 to 10 points for severity. The scoring is expressed similarly to the TNM (tumour, nodes, metastasis) tumour classification, for example as H5W4P2. The maximum severity index is 30 points. A severity grade of mild is between 1 and 8 points, moderate between 9 and 16 points and severe 17 points and over. In the author's series, the grades were mild in eight, moderate in 21 and severe in 15 cases. The functional severity grading should allow better comparison of radially deficient limbs and the results of treatment between groups of patients. © The Author(s) 2014.

  15. Analogous mechanism regulating formation of neocortical basal radial glia and cerebellar Bergmann glia

    PubMed Central

    Heng, Xin; Guo, Qiuxia; Leung, Alan W; Li, James YH

    2017-01-01

    Neocortical basal radial glia (bRG) and cerebellar Bergmann glia (BG) are basal progenitors derived from ventricular apical radial glia (aRG) that selectively lose their apical processes. bRG and BG have been implicated in the expansion and folding of the cerebrum and cerebellum, respectively. Here, we analyzed the molecular characteristics and development of bRG and BG. Transcriptomic comparison revealed striking similarity of the molecular features of bRG and BG. We found that heightened ERK signaling activity in aRG is tightly linked to the temporal formation and the relative abundance of bRG in human and mouse cortices. Forced activation of an FGF-ERK-ETV axis that is crucial to BG induction specifically induced bRG with canonical human bRG features in mice. Therefore, our data point to a common mechanism of bRG and BG generation, bearing implications to the role for these basal progenitors in the evolution of cortical folding of the cerebrum and cerebellum. DOI: http://dx.doi.org/10.7554/eLife.23253.001 PMID:28489004

  16. RADIAL STABILITY IN STRATIFIED STARS

    SciTech Connect

    Pereira, Jonas P.; Rueda, Jorge A. E-mail: jorge.rueda@icra.it

    2015-03-01

    We formulate within a generalized distributional approach the treatment of the stability against radial perturbations for both neutral and charged stratified stars in Newtonian and Einstein's gravity. We obtain from this approach the boundary conditions connecting any two phases within a star and underline its relevance for realistic models of compact stars with phase transitions, owing to the modification of the star's set of eigenmodes with respect to the continuous case.

  17. Velocidades radiales en Collinder 121

    NASA Astrophysics Data System (ADS)

    Arnal, M.; Morrell, N.

    Se han llevado a cabo observaciones espectroscópicas de unas treinta estrellas que son posibles miembros del cúmulo abierto Collinder 121. Las mismas fueron realizadas con el telescopio de 2.15m del Complejo Astronómico El Leoncito (CASLEO). El análisis de las velocidades radiales derivadas del material obtenido, confirma la realidad de Collinder 121, al menos desde el punto de vista cinemático. La velocidad radial baricentral (LSR) del cúmulo es de +17 ± 3 km.s-1. Esta velocidad coincide, dentro de los errores, con la velocidad radial (LSR) de la nebulosa anillo S308, la cual es de ~20 ± 10 km.s-1. Como S308 se encuentra físicamente asociada a la estrella Wolf-Rayet HD~50896, es muy probable que esta última sea un miembro de Collinder 121. Desde un punto de vista cinemático, la supergigante roja HD~50877 (K3Iab) también pertenecería a Collinder 121. Basándonos en la pertenencia de HD~50896 a Collinder 121, y en la interacción encontrada entre el viento de esta estrella y el medio interestelar circundante a la misma, se estima para este cúmulo una distancia del orden de 1 kpc.

  18. Attractive and Repulsive Forces on Particles in Oscillatory Flow

    NASA Astrophysics Data System (ADS)

    Agarwal, Siddhansh; Rallabandi, Bhargav; Raju, David; Thameem, Raqeeb; Hilgenfeldt, Sascha

    2016-11-01

    A large class of oscillating flows gives rise to rectified streaming motion of the fluid. It has recently been shown that particle transport in such flows, excited by bubbles oscillating at ultrasound frequencies, leads to differential displacement and efficient sorting of microparticles by size. We derive a general expression for the instantaneous radial force experienced by a small spherical particle in the vicinity of an oscillating interface, and generalize the radial projection of the Maxey-Riley equation to include this effect. Varying relevant system parameters, we show that the net effect on the particle can be either an attraction to or a repulsion from the bubble surface, depending in particular on the particle size and the particle/fluid density contrast. We demonstrate that these predictions are in agreement with a variety of experiments.

  19. Brain-derived neurotrophic factor as a driving force behind neuroplasticity in neuropathic and central sensitization pain: a new therapeutic target?

    PubMed

    Nijs, Jo; Meeus, Mira; Versijpt, Jan; Moens, Maarten; Bos, Inge; Knaepen, Kristel; Meeusen, Romain

    2015-04-01

    Central sensitization is a form of maladaptive neuroplasticity underlying many chronic pain disorders, including neuropathic pain, fibromyalgia, whiplash, headache, chronic pelvic pain syndrome and some forms of osteoarthritis, low back pain, epicondylitis, shoulder pain and cancer pain. Brain-derived neurotrophic factor (BDNF) is a driving force behind neuroplasticity, and it is therefore crucial for neural maintenance and repair. However, BDNF also contributes to sensitization of pain pathways, making it an interesting novel therapeutic target. An overview of BDNF's sensitizing capacity at every level of the pain pathways is presented, including the peripheral nociceptors, dorsal root ganglia, spinal dorsal horn neurons, and brain descending inhibitory and facilitatory pathways. This is followed by the presentation of several potential therapeutic options, ranging from indirect influencing of BDNF levels (using exercise therapy, anti-inflammatory drugs, melatonin, repetitive transcranial magnetic stimulation) to more specific targeting of BDNF's receptors and signaling pathways (blocking the proteinase-activated receptors 2-NK-κβ signaling pathway, administration of phencyclidine for antagonizing NMDA receptors, or blockade of the adenosine A2A receptor). This section focuses on combining pharmacotherapy with multimodal rehabilitation for balancing the deleterious and therapeutic effects of BNDF treatment in chronic pain patients, as well as accounting for the complex and biopsychosocial nature of chronic pain.

  20. On Beam-like Functions with Radial Symmetry

    SciTech Connect

    Papanicolaou, N. C.; Christov, C. I.

    2008-10-30

    In this work, we introduce a complete orthonormal (CON) set of functions as the eigenfunctions of a fourth-order boundary problem with radial symmetry. We derive the relation for the spectrum of the problem and solve it numerically. For larger indices n of the eigenvalues we derive accurate asymptotic representations valid within o(n{sup -2}).Two model fourth order problems with radial symmetry which admit exact analytic solutions are featured: a simple problem involving only the fourth-order radial operator and a constant and the other also involving the second-order radial operator. We show that for both cases, the rate of convergence is O(N{sup -5}) which is compatible with theoretical predictions. The spectral and analytic solutions are found to be in excellent agreement. With 20 terms the absolute pointwise difference of the spectral and analytical solutions is of order 10{sup -7} which means that the fifth order algebraic rate of convergence is fully adequate.

  1. Radial tears of the menisci: MR findings.

    PubMed

    Tuckman, G A; Miller, W J; Remo, J W; Fritts, H M; Rozansky, M I

    1994-08-01

    Radial meniscal tears have a plane of cleavage oriented across the short axis of the meniscus in the same plane in which radial images are oriented. These tears are important to recognize, because they have clinical implications different from those of other meniscal tears with respect to meniscal function, orthopedic treatment, and clinical course. Depending on their size, location, and orientation, radial tears can have different appearances on standard MR images. Certain types can be fairly subtle to diagnose. The purpose of this essay is to illustrate the varied appearances of radial tears on MR images and the findings commonly associated with radial tears.

  2. Radial Wettable Gradient of Hot Surface to Control Droplets Movement in Directions

    NASA Astrophysics Data System (ADS)

    Feng, Shile; Wang, Sijie; Tao, Yuanhao; Shang, Weifeng; Deng, Siyan; Zheng, Yongmei; Hou, Yongping

    2015-05-01

    A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology.

  3. Radial Wettable Gradient of Hot Surface to Control Droplets Movement in Directions

    PubMed Central

    Feng, Shile; Wang, Sijie; Tao, Yuanhao; Shang, Weifeng; Deng, Siyan; Zheng, Yongmei; Hou, Yongping

    2015-01-01

    A radial wettable gradient was fabricated on the surface of graphite plate by a simple one-step anodic oxidation process. It was found that the direction and value of the wettable gradient could be easily controlled by adjusting current and oxidation time gradient. With the increase of surface temperature, droplets on surface not only exhibited the transition of boiling mode, but also showed the controlled radial spreading, evaporation and movement behaviors. These phenomena could be attributed to the cooperation of wettability force, hysteresis force and vapor pressure (Leidenfrost effect). Especially, the controlled radial convergence or divergence of droplets with high velocity were realized on the surfaces with either inside or outside radial gradient, which would have crucial applications in the design of microfluidic devices and the exploration of the biotechnology. PMID:25975722

  4. Current approach to radial nerve paralysis.

    PubMed

    Lowe, James B; Sen, Subhro K; Mackinnon, Susan E

    2002-09-15

    After studying this article, the participant should be able to: 1. Identify all potential points of radial nerve compression and other likely causes of radial nerve injury. 2. Accurately diagnose both surgical and nonsurgical causes of radial nerve paralysis. 3. Define a safe and effective approach to the surgical release and reconstruction of the radial nerve. Radial nerve paralysis, which can result from a complex humerus fracture, direct nerve trauma, compressive neuropathies, neuritis, or (rarely) from malignant tumor formation, has been reported throughout the literature, with some controversy regarding its diagnosis and management. The appropriate management of any radial nerve palsy depends primarily on an accurate determination of its cause, severity, duration, and level of involvement. The radial nerve can be injured as proximally as the brachial plexus or as distally as the posterior interosseous or radial sensory nerve. This article reviews the etiology, prognosis, and various treatments available for radial nerve paralysis. It also provides a new classification system and treatment algorithm to assist in the management of patients with radial nerve palsies, and it offers a simple, five-step approach to radial nerve release in the forearm.

  5. Radial vibrations of BPS skyrmions

    NASA Astrophysics Data System (ADS)

    Adam, C.; Haberichter, M.; Romanczukiewicz, T.; Wereszczynski, A.

    2016-11-01

    We study radial vibrations of spherically symmetric Skyrmions in the Bogomol'nyi-Prasad-Sommerfield Skyrme model. Concretely, we numerically solve the linearized field equations for small fluctuations in a Skyrmion background, both for linearly stable oscillations and for (unstable) resonances. This is complemented by numerical solutions of the full nonlinear system, which confirm all the results of the linear analysis. In all cases, the resulting fundamental excitation provides a rather accurate value for the Roper resonance, supporting the hypothesis that the Bogomol'nyi-Prasad-Sommerfield Skyrme model already gives a reasonable approximate description of this resonance. Furthermore, for many potentials additional higher resonances appear, again in agreement with known experimental results.

  6. PRECISION RADIAL VELOCITIES WITH CSHELL

    SciTech Connect

    Crockett, Christopher J.; Prato, L.; Mahmud, Naved I.; Johns-Krull, Christopher M.; Jaffe, Daniel T.; Beichman, Charles A. E-mail: lprato@lowell.edu E-mail: cmj@rice.edu

    2011-07-10

    Radial velocity (RV) identification of extrasolar planets has historically been dominated by optical surveys. Interest in expanding exoplanet searches to M dwarfs and young stars, however, has motivated a push to improve the precision of near-infrared RV techniques. We present our methodology for achieving 58 m s{sup -1} precision in the K band on the M0 dwarf GJ 281 using the CSHELL spectrograph at the 3 m NASA Infrared Telescope Facility. We also demonstrate our ability to recover the known 4 M{sub JUP} exoplanet Gl 86 b and discuss the implications for success in detecting planets around 1-3 Myr old T Tauri stars.

  7. Heterogeneous force network in 3D cellularized collagen networks.

    PubMed

    Liang, Long; Jones, Christopher; Chen, Shaohua; Sun, Bo; Jiao, Yang

    2016-10-25

    Collagen networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the transmission of forces generated by contractile cells in 3D collagen-I networks. Specifically, the graph (bond-node) representations of collagen networks with collagen concentrations of 1, 2 and 4 mg ml(-1) are derived from confocal microscopy data and used to model the network microstructure. Cell contraction is modeled by applying correlated displacements at specific nodes of the network, representing the focal adhesion sites. A nonlinear elastic model is employed to characterize the mechanical behavior of individual fiber bundles including strain hardening during stretching and buckling under compression. A force-based relaxation method is employed to obtain equilibrium network configurations under cell contraction. We find that for all collagen concentrations, the majority of the forces are carried by a small number of heterogeneous force chains emitted from the contracting cells, which is qualitatively consistent with our experimental observations. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to fiber reorientation induced by cell contraction. The decay of the forces along the force chains is significantly slower than the decay of radially averaged forces in the system, suggesting that the fibreous nature of biopolymer network structure can support long-range force transmission. The force chains emerge even at very small cell contractions, and the number of force chains increases with increasing cell contraction. At large cell contractions, the fibers close to the cell surface are in the nonlinear regime, and the nonlinear region is localized in a small neighborhood of the cell. In addition, the number of force chains increases with increasing collagen concentration, due to the larger number of focal adhesion sites

  8. Heterogeneous force network in 3D cellularized collagen networks

    NASA Astrophysics Data System (ADS)

    Liang, Long; Jones, Christopher; Chen, Shaohua; Sun, Bo; Jiao, Yang

    2016-12-01

    Collagen networks play an important role in coordinating and regulating collective cellular dynamics via a number of signaling pathways. Here, we investigate the transmission of forces generated by contractile cells in 3D collagen-I networks. Specifically, the graph (bond-node) representations of collagen networks with collagen concentrations of 1, 2 and 4 mg ml-1 are derived from confocal microscopy data and used to model the network microstructure. Cell contraction is modeled by applying correlated displacements at specific nodes of the network, representing the focal adhesion sites. A nonlinear elastic model is employed to characterize the mechanical behavior of individual fiber bundles including strain hardening during stretching and buckling under compression. A force-based relaxation method is employed to obtain equilibrium network configurations under cell contraction. We find that for all collagen concentrations, the majority of the forces are carried by a small number of heterogeneous force chains emitted from the contracting cells, which is qualitatively consistent with our experimental observations. The force chains consist of fiber segments that either possess a high degree of alignment before cell contraction or are aligned due to fiber reorientation induced by cell contraction. The decay of the forces along the force chains is significantly slower than the decay of radially averaged forces in the system, suggesting that the fibreous nature of biopolymer network structure can support long-range force transmission. The force chains emerge even at very small cell contractions, and the number of force chains increases with increasing cell contraction. At large cell contractions, the fibers close to the cell surface are in the nonlinear regime, and the nonlinear region is localized in a small neighborhood of the cell. In addition, the number of force chains increases with increasing collagen concentration, due to the larger number of focal adhesion sites

  9. Radial orbit instability in systems of highly eccentric orbits: Antonov problem reviewed

    NASA Astrophysics Data System (ADS)

    Polyachenko, E. V.; Shukhman, I. G.

    2017-09-01

    Stationary stellar systems with radially elongated orbits are subject to radial orbit instability - an important phenomenon that structures galaxies. Antonov presented a formal proof of the instability for spherical systems in the limit of purely radial orbits. However, such spheres have highly inhomogeneous density distributions with singularity ∼1/r2, resulting in an inconsistency in the proof. The proof can be refined, if one considers an orbital distribution close to purely radial, but not entirely radial, which allows to avoid the central singularity. For this purpose we employ non-singular analogues of generalized polytropes elaborated recently in our work in order to derive and solve new integral equations adopted for calculation of unstable eigenmodes in systems with nearly radial orbits. In addition, we establish a link between our and Antonov's approaches and uncover the meaning of infinite entities in the purely radial case. Maximum growth rates tend to infinity as the system becomes more and more radially anisotropic. The instability takes place both for even and odd spherical harmonics, with all unstable modes developing rapidly, i.e. having eigenfrequencies comparable to or greater than typical orbital frequencies. This invalidates orbital approximation in the case of systems with all orbits very close to purely radial.

  10. Nonstandard jump functions for radially symmetric shock waves

    SciTech Connect

    Baty, Roy S.; Tucker, Don H.; Stanescu, Dan

    2008-10-01

    Nonstandard analysis is applied to derive generalized jump functions for radially symmetric, one-dimensional, magnetogasdynamic shock waves. It is assumed that the shock wave jumps occur on infinitesimal intervals, and the jump functions for the physical parameters occur smoothly across these intervals. Locally integrable predistributions of the Heaviside function are used to model the flow variables across a shock wave. The equations of motion expressed in nonconservative form are then applied to derive unambiguous relationships between the jump functions for the physical parameters for two families of self-similar flows. It is shown that the microstructures for these families of radially symmetric, magnetogasdynamic shock waves coincide in a nonstandard sense for a specified density jump function

  11. Mapping the radial structure of AGN tori

    NASA Astrophysics Data System (ADS)

    Kishimoto, M.; Hönig, S. F.; Antonucci, R.; Millour, F.; Tristram, K. R. W.; Weigelt, G.

    2011-12-01

    We present mid-IR interferometric observations of six type 1 AGNs at multiple baseline lengths ranging from 27 m to 130 m, reaching high angular resolutions up to λ/B ~ 0.02 arcsec. For two of the targets, we have simultaneous near-IR interferometric measurements as well, taken within a week. We find that all the objects are partially resolved at long baselines in these IR wavelengths. The multiple-baseline data directly probe the radial distribution of the material on sub-pc scales. We show that for our sample, which is small but spans over ~2.5 orders of magnitudes in the UV/optical luminosity L of the central engine, the radial distribution clearly and systematically changes with luminosity. The brightness distribution at a given mid-IR wavelength seems to be rather well described by a power law, which makes a simple Gaussian or ring size estimation quite inadequate. In this case, a half-light radius R1/2 can be used as a representative size. We show that the higher luminosity objects become more compact in normalized half-light radii R1/2/Rin in the mid-IR, where Rin is the dust sublimation radius empirically given by the L1/2 fit of the near-IR reverberation radii. This means that, contrary to previous studies, the physical mid-IR emission size (e.g. in pc) is not proportional to L1/2, but increases with L much more slowly. With our current datasets, we find that R1/2 ∝ L0.21 ± 0.05 at 8.5 μm, and R1/2 nearly constant at 13 μm. The derived size information also seems to correlate with the properties of the total flux spectrum, in particular the smaller R1/2/Rin objects having bluer mid-IR spectral shape. We use a power-law temperature/density gradient model as a reference, and infer that the radial surface density distribution of the heated dust grains at a radius r changes from a steep ~r-1 structure in high luminosity objects to a shallower ~r0 structure in those of lower luminosity. The inward dust temperature distribution does not seem to smoothly

  12. New constraints on Earth's radial conductivity structure

    NASA Astrophysics Data System (ADS)

    Püthe, Christoph; Kuvshinov, Alexey; Olsen, Nils; Sabaka, Terence

    2014-05-01

    We present a new model of Earth's radial (1-D) conductivity structure at depths between 10 km and the core-mantle boundary. It is based on CM5, the latest version in the Comprehensive Model series that has been derived using 13 years (September 2000 to September 2013) of magnetic data collected by the three satellites Oersted, CHAMP and SAC-C and at the global network of geomagnetic observatories. CM5 describes contributions due to sources in core, lithosphere, ionosphere and magnetosphere (and corresponding induced parts) in form of spherical harmonic expansion (SHE) coefficients. Removing predictions of the core, lithospheric and ionospheric field contributions as given by CM5 from the observations, we determine time series of the dominating external and induced SHE coefficients of the magnetic potential due to the magnetospheric ring current. Scalar Q-responses are estimated from these coefficients. An iterative approach is used to correct the estimated responses for 3-D effects arising from lateral heterogeneities in the top 10 km. The corrected Q-responses are converted to C-responses; the latter are subsequently inverted for the layered 1-D mantle conductivity profile with the Newton method. The Hessian matrix of the misfit function, which is derived analytically, is used to estimate confidence limits for the conductivity of each layer. The resulting conductivity-depth profile is compared to 1-D conductivity models of Earth's mantle recovered in previous studies.

  13. Socket stars: UBVRJIK radial profiles

    NASA Astrophysics Data System (ADS)

    Schaefer, Bradley E.

    1995-05-01

    Visual inspectin of stars embedded in H II nebulae has shown a significant fraction to be surrounded by nearly symmetric extended regions within which the nebular brightness is apparently significantly fainter than is typical for the surrounding area. These 'socket stars' might be caused by a bubble in the nebula blown out by a stellar wind or they might be caused by a circumstellar envelope of dust hiding the emission behind the star. As such, the sockets could be the first manifestation of a previously unknown component of pre-main-sequence stars. Unfortunately, no quantitative proof of the existence of sockets has been presented. To fill this need, I have imaged 10 socket stars and six background stars with CCD cameras and infrared array cameras. From these images, I have constructed radial plots which should reveal dips in brightness immediately outside the seeing disk. The radial plots do not show any evidence for the existence of sockets. A detailed examination of the photographs orginally used to identify the sockets show that the causes of these reports are (1) artifacts resulting from the photographic process of dodging and (2) random coincidence of stars with local minima in nebular brightness. Thus, I conclude that 'socket stars' do not exist.

  14. Planar radial weakly dissipative diffeomorphisms.

    PubMed

    Simó, C; Vieiro, A

    2010-12-01

    We study the effect of a small dissipative radial perturbation acting on a one parameter family of area preserving diffeomorphisms. This is a specific type of dissipative perturbation. The interest is on the global effect of the dissipation on a fixed domain around an elliptic fixed/periodic point of the family, rather than on the effects around a single resonance. We describe the local/global bifurcations observed in the transition from the conservative to a weakly dissipative case: the location of the resonant islands, the changes in the domains of attraction of the foci inside these islands, how the resonances disappear, etc. The possible ω-limits are determined in each case. This topological description gives rise to three different dynamical regimes according to the size of dissipative perturbation. Moreover, we determine the conservative limit of the probability of capture in a generic resonance from the interpolating flow approximation, hence assuming no homoclinics in the resonance. As a paradigm of weakly dissipative radial maps, we use a dissipative version of the Hénon map. © 2010 American Institute of Physics.

  15. Radial velocities from automated telescopes

    NASA Astrophysics Data System (ADS)

    Pepe, F.; Mayor, M.

    2004-10-01

    During the past years, precise radial-velocity measurements have been the fundamental tool for the discovery and characterization of almost all the presently known extra-solar planets. The increasing precision and efficiency of this technique has also opened new possibilities for the follow-up of planetary transit candidates, as well as for other fields of astronomy, such as asteroseismology and stellar physics. The example of extra-solar planets illustrates quite clearly the strong need for large observational surveys: 1) In order to get a complete view of the planet "zoo", many stars of various types must be measured and followed up. 2) The detection efficiency increases enormously with the quality and the quantity of data points. Time sampling is a critical parameter. 3) The great diversity of known planetary systems requires covering observation time-scales from one night to several years and even decades. A direct consequence of these factors is that survey programmes require a large amount of telescope time and a continuous follow-up of the observations. In a context of limited resources and large amounts of data, automated telescopes will be of great help, or even required, to carry out these programmes. Based on our experience with CORALIE and HARPS, we shall try to define a series of "requirements" towards automated telescopes for precise radial-velocity measurements.

  16. A new nonenzymatic method and device to obtain a fat tissue derivative highly enriched in pericyte-like elements by mild mechanical forces from human lipoaspirates.

    PubMed

    Bianchi, Francesca; Maioli, Margherita; Leonardi, Erika; Olivi, Elena; Pasquinelli, Gianandrea; Valente, Sabrina; Mendez, Armando J; Ricordi, Camillo; Raffaini, Mirco; Tremolada, Carlo; Ventura, Carlo

    2013-01-01

    Adipose tissue contains multipotent elements with phenotypic and gene expression profiles similar to human mesenchymal stem cells (hMSCs) and pericytes. The chance of clinical translation of the multilineage potential of these cells is delayed by the poor/negligible cell survival within cryopreserved lipoaspirates, the difficulty of ex vivo expansion, and the complexity of current Good Manufacturing Practice (cGMP) requirements for expanded cells. Hence, availability of a minimally manipulated, autologous, hMSC/pericyte-enriched fat product would have remarkable biomedical and clinical relevance. Here, we present an innovative system, named Lipogems, providing a nonexpanded, ready-to-use fat product. The system uses mild mechanical forces in a completely closed system, avoiding enzymes, additives, and other manipulations. Differently from unprocessed lipoaspirate, the nonexpanded Lipogems product encompasses a remarkably preserved vascular stroma with slit-like capillaries wedged between adipocytes and stromal stalks containing vascular channels with evident lumina. Immunohistochemistry revealed that Lipogems stromal vascular tissue included abundant cells with pericyte/hMSC identity. Flow cytometry analysis of nonexpanded, collagenase-treated Lipogems product showed that it was comprised with a significantly higher percentage of mature pericytes and hMSCs, and lower amount of hematopoietic elements, than enzymatically digested lipoaspirates. Differently from the lipoaspirate, the distinctive traits of freshly isolated Lipogems product were not altered by cryopreservation. Noteworthy, the features of fresh product were retained in the Lipogems product obtained from human cadavers, paving the way to an off-the-shelf strategy for reconstructive procedures and regenerative medicine. When placed in tissue culture medium, the Lipogems product yielded a highly homogeneous adipose tissue-derived hMSC population, exhibiting features of hMSCs isolated from other sources

  17. Radial deformation of the earth by oceanic tidal loading

    NASA Technical Reports Server (NTRS)

    Ray, R. D.; Sanchez, B. V.

    1989-01-01

    A high-degree spherical harmonic series is used to compute the radial deformation of the Earth by oceanic tidal loading. By exploiting fast numerical transforms, this approach is found to be much more efficient, but no less accurate, than the traditional Green's function approach. The method is used to derive an atlas of load tide maps for 10 constitutents of the NSWC ocean tide model.

  18. Prediction of hydration free energies for aliphatic and aromatic chloro derivatives using molecular dynamics simulations with the OPLS-AA force field

    NASA Astrophysics Data System (ADS)

    Beckstein, Oliver; Iorga, Bogdan I.

    2012-05-01

    All-atom molecular dynamics computer simulations were used to blindly predict the hydration free energies of a range of chloro-organic compounds as part of the SAMPL3 challenge. All compounds were parameterized within the framework of the OPLS-AA force field, using an established protocol to compute the absolute hydration free energy via a windowed free energy perturbation approach and thermodynamic integration. Three different approaches to deriving partial charge parameters were pursued: (1) using existing OPLS-AA atom types and charges with minor adjustments of partial charges on equivalent connecting atoms; (2) calculation of quantum mechanical charges via geometry optimization, followed by electrostatic potential (ESP) fitting, using Jaguar at the LMP2/cc-pVTZ(-F) level; and (3) via geometry optimization and CHelpG charges (Gaussian03 at the HF/6-31G* level), followed by two-stage RESP fitting. Protocol 3 generated the most accurate predictions with a root mean square (RMS) error of 1.2 kcal mol^{-1} for the entire data set. It was found that the deficiency of the standard OPLS-AA parameters, protocol 1 (RMS error 2.4 kcal mol^{-1} overall), was mostly due to compounds with more than three chlorine substituents on an aromatic ring. For this latter subset, the RMS errors were 1.4 kcal mol^{-1} (protocol 3) and 4.3 kcal mol^{-1} (protocol 1), respectively. We propose new OPLS-AA atom types for aromatic carbon and chlorine atoms in rings with ≥4 Cl-substituents that perform better than the best QM-based approach, resulting in an RMS error of 1.2 kcal mol^{-1} for these difficult compounds.

  19. Negative effects of ultrafine particle exposure during forced exercise on the expression of Brain-Derived Neurotrophic Factor in the hippocampus of rats.

    PubMed

    Bos, I; De Boever, P; Int Panis, L; Sarre, S; Meeusen, R

    2012-10-25

    Exercise improves cognitive function, and Brain-Derived Neurotrophic Factor (BDNF) plays a key role in this process. We recently reported that particulate matter (PM) exposure negatively contributed to the exercise-induced increase in human serum BDNF concentration. Furthermore, PM exposure is associated with neuroinflammation and cognitive decline. The aim of this study was to investigate the effect of exposure to ultrafine particles (UFP) during a single bout of forced exercise on the expression of inflammatory (IL1α, IL1β, TNF, IL6, NOS2, NOS3) and oxidative stress (NFE2L2)-related genes, as well as BDNF in the brain of rats. Four groups (n=6/group) of Wistar rats were exposed for 90 min to one of the following exposure regimes: UFP+exercise, UFP+rest, ambient air+exercise, ambient air+rest (control). Hippocampus, olfactory bulb and prefrontal cortex were collected 24h after exposure. Gene expression changes were analyzed with real-time PCR. In the condition ambient air+exercise, hippocampal expression of BDNF and NFE2L2 was up-regulated, while the expression of IL1α and NOS3 in the prefrontal cortex and IL1α in the olfactory bulb was down-regulated compared to the control. In contrast, gene expression in the condition UFP+exercise did not differ from the control. In the condition UFP+rest, hippocampal expression of NFE2L2 was down-regulated and there was a trend toward down-regulation of BDNF expression compared to the control. This study shows a negative effect of UFP exposure on the exercise-induced up-regulation of BDNF gene expression in the hippocampus of rats.

  20. Prediction of hydration free energies for aliphatic and aromatic chloro derivatives using molecular dynamics simulations with the OPLS-AA force field.

    PubMed

    Beckstein, Oliver; Iorga, Bogdan I

    2012-05-01

    All-atom molecular dynamics computer simulations were used to blindly predict the hydration free energies of a range of chloro-organic compounds as part of the SAMPL3 challenge. All compounds were parameterized within the framework of the OPLS-AA force field, using an established protocol to compute the absolute hydration free energy via a windowed free energy perturbation approach and thermodynamic integration. Three different approaches to deriving partial charge parameters were pursued: (1) using existing OPLS-AA atom types and charges with minor adjustments of partial charges on equivalent connecting atoms; (2) calculation of quantum mechanical charges via geometry optimization, followed by electrostatic potential (ESP) fitting, using Jaguar at the LMP2/cc-pVTZ(-F) level; and (3) via geometry optimization and CHelpG charges (Gaussian03 at the HF/6-31G* level), followed by two-stage RESP fitting. Protocol 3 generated the most accurate predictions with a root mean square (RMS) error of 1.2 kcal mol(-1) for the entire data set. It was found that the deficiency of the standard OPLS-AA parameters, protocol 1 (RMS error 2.4 kcal mol(-1) overall), was mostly due to compounds with more than three chlorine substituents on an aromatic ring. For this latter subset, the RMS errors were 1.4 kcal mol(-1) (protocol 3) and 4.3 kcal mol(-1) (protocol 1), respectively. We propose new OPLS-AA atom types for aromatic carbon and chlorine atoms in rings with ≥4 Cl-substituents that perform better than the best QM-based approach, resulting in an RMS error of 1.2 kcal mol(-1) for these difficult compounds.

  1. Grinding forces and energy

    SciTech Connect

    Brach, K.; Pai, D.M.; Ratterman, E.; Shaw, M.C.

    1987-01-01

    Grinding forces and energy plan an important role in all abrasive machining operations. While specific grinding energy may be obtained from workpiece dynamometer values or by measuring spindle power, care must be exercised in converting dynamometer reading into power consumed. This is particularly true for operations involving a large ratio of wheel depth of cut to wheel diameter or when the radial force on the wheel is large relative to the tangential component. Interpretation of workpiece dynamometer results are discussed and several specific examples are considered including the diamond sawing of granite and the creep feed grinding of metal.

  2. Grinding forces and energy

    SciTech Connect

    Brach, K.; Pai, D.M.; Ratterman, E.; Shaw, M.C.

    1988-02-01

    Grinding forces and energy play an important role in all abrasive machining operations. While specific grinding energy may be obtained from workpiece dynamometer values or by measuring spindle power, care must be exercised in converting dynamometer reading into power consumed. This is particularly true for operations involving a large ratio of wheel depth of cut to wheel diameter or when the radial force on the wheel is large relative to the tangential component. Interpretation of workpiece dynamometer results are discussed and several specific examples are considered including the diamond sawing of granite and the creep feed grinding of metal.

  3. Propagation of a radial phased-locked Lorentz beam array in turbulent atmosphere.

    PubMed

    Zhou, Guoquan

    2011-11-21

    A radial phased-locked (PL) Lorentz beam array provides an appropriate theoretical model to describe a coherent diode laser array, which is an efficient radiation source for high-power beaming use. The propagation of a radial PL Lorentz beam array in turbulent atmosphere is investigated. Based on the extended Huygens-Fresnel integral and some mathematical techniques, analytical formulae for the average intensity and the effective beam size of a radial PL Lorentz beam array are derived in turbulent atmosphere. The average intensity distribution and the spreading properties of a radial PL Lorentz beam array in turbulent atmosphere are numerically calculated. The influences of the beam parameters and the structure constant of the atmospheric turbulence on the propagation of a radial PL Lorentz beam array in turbulent atmosphere are discussed in detail. © 2011 Optical Society of America

  4. The radial plasma structure of 1E 0102.2-7219

    NASA Astrophysics Data System (ADS)

    Flanagan, K. A.; Canizares, C. R.; Houck, J. C.; Fredericks, A. C.

    Chandra High Energy Transmission Grating Spectrometer observations of 1E 0102 2-7219 have revealed marked radial dependence in its ionization structure Flanagan it et al 2004 In order to explore intrinsic radial variations of temperature or other plasma parameters line ratios may provide useful diagnostics if projection effects are taken into account We have approached this problem using a spatial model of the emission including orientation angular and radial distribution We use MARX to simulate observations of a 3D SNR emissivity distribution and compare these simulations with the actual X-ray line image to fit radial distributions of key diagnostic lines Plasma parameters are derived by forming ratios from the best-fit radial models for each X-ray line We find that ionization age and electron temperature increase smoothly with radius We examine the implications with regard to electron density shock velocity and electron-ion equilibration

  5. THE SPIN EFFECT ON PLANETARY RADIAL VELOCIMETRY OF EXOPLANETS

    SciTech Connect

    Kawahara, Hajime

    2012-11-20

    We consider the effect of planetary spin on the planetary radial velocity (PRV) in dayside spectra of exoplanets. To understand the spin effect qualitatively, we derive an analytic formula of the intensity-weighted radial velocity from the planetary surface on the following assumptions: (1) constant and solid rotation without precession, (2) stable and uniform distribution of molecules/atoms, (3) emission models from the dayside hemisphere, and (4) a circular orbit. On these assumptions, we find that the curve of the PRV is distorted by the planetary spin and this anomaly is characterized by the spin radial velocity at the equator and a projected angle on a celestial plane between the spin axis and the axis of orbital motion {lambda}{sub p} in a manner analogous to the Rossiter-McLaughlin effect. The latter can constrain the planetary obliquity. Creating mock PRV data with 3 km s{sup -1} accuracy, we demonstrate how {lambda}{sub p} and the spin radial velocity at the equator are estimated. We find that the stringent constraint of eccentricity is crucial to detect the spin effect. Though our formula is still qualitative, we conclude that the PRV in the dayside spectra will be a powerful means for constraining the planetary spin.

  6. Surface interpolation with radial basis functions for medical imaging

    SciTech Connect

    Carr, J.C.; Beatson, R.K.; Fright, W.R.

    1997-02-01

    Radial basis functions are presented as a practical solution to the problem of interpolating incomplete surfaces derived from three-dimensional (3-D) medical graphics. The specific application considered is the design of cranial implants for the repair of defects, usually holes, in the skull. Radial basis functions impose few restrictions on the geometry of the interpolation centers and are suited to problems where interpolation centers do not form a regular grid. However, their high computational requirements have previously limited their use to problems where the number of interpolation centers is small (<300). Recently developed fast evaluation techniques have overcome these limitations and made radial basis interpolation a practical approach for larger data sets. In this paper radial basis functions are fitted to depth-maps of the skull`s surface, obtained from X-ray computed tomography (CT) data using ray-tracing techniques. They are used to smoothly interpolate the surface of the skull across defect regions. The resulting mathematical description of the skull`s surface can be evaluated at any desired resolution to be rendered on a graphics workstation or to generate instructions for operating a computer numerically controlled (CNC) mill.

  7. High precision radial velocities: the case for NIR.

    NASA Astrophysics Data System (ADS)

    Carleo, I.; Gratton, R.

    In the context of the preparation for the high resolution spectrograph HIRES for E-ELT, we are studying the possibility to derive high-precision radial velocities (RV) on a prototype:GIANO, the near-infrared (NIR) echelle spectrograph now available at the Telescopio Nazionale Galileo. Radial velocities measured from near-infrared spectra are a potential tool to search for extrasolar planets around cool stars. High resolution infrared spectrographs now available are reaching the high precision of visible instruments, with a constant improvement over time. In particular, no other IR instruments have GIANO's capability to cover the entire NIR wavelength range. We have developed an ensemble of IDL procedures to measure high precision radial velocities on GIANO spectra. Taking into account the achieved precisions with GIANO, we constrain the sample of targets for which GIANO is better than HARPS-N, but with the advent of GIARPS (GIANO+HARPS-N), GIANO will improve its performances and include a much larger sample of stars. The NIR range is the future of RV measurements, especially because the jitter due to the star surface activities is reduced in the NIR. As a consequence, HIRES working in NIR range might be very useful, and for a wide range of cases, it will be more efficient than HIRES working in the visible range, for detection and characterization of planets using radial velocity technique.

  8. Radial flow pulse jet mixer

    DOEpatents

    VanOsdol, John G.

    2013-06-25

    The disclosure provides a pulse jet mixing vessel for mixing a plurality of solid particles. The pulse jet mixing vessel is comprised of a sludge basin, a flow surface surrounding the sludge basin, and a downcoming flow annulus between the flow surface and an inner shroud. The pulse jet mixing vessel is additionally comprised of an upper vessel pressurization volume in fluid communication with the downcoming flow annulus, and an inner shroud surge volume separated from the downcoming flow annulus by the inner shroud. When the solid particles are resting on the sludge basin and a fluid such as water is atop the particles and extending into the downcoming flow annulus and the inner shroud surge volume, mixing occurs by pressurization of the upper vessel pressurization volume, generating an inward radial flow over the flow surface and an upwash jet at the center of the sludge basin.

  9. Numerical and experimental study of unsteady flow field and vibration in radial inflow turbines

    SciTech Connect

    Kreuz-Ihli, T.; Filsinger, D.; Schulz, A.; Wittig, S.

    2000-04-01

    The blades of turbocharger impellers are exposed to unsteady aerodynamic forces, which cause blade vibrations and may lead to failures. An indispensable requirement for a safe design of radial inflow turbines is a detailed knowledge of the exciting forces. Up to now, only a few investigations relating to unsteady aerodynamic forces in radial turbines have been presented. To give a detailed insight into the complex phenomena, a comprehensive research project was initiated at the Institut fuer Thermische Stroemungsmaschinen, at the University of Karlsruhe. A turbocharger test rig was installed in the high-pressure, high-temperature laboratory of the institute. The present paper gives a description of the test rig design and the measuring techniques. The flow field in a vaneless radial inflow turbine was analyzed using laser-Doppler anemometry. First results of unsteady flow field investigations in the turbine scroll and unsteady phase-resolved measurements of the flow field in the turbine rotor will be discussed. Moreover, results from finite element calculations analyzing frequencies and mode shapes are presented. As vibrations in turbines of turbochargers are assumed to be predominantly excited by unsteady aerodynamic forces, a method to predict the actual transient flow in a radial turbine utilizing the commercial Navier-Stokes solver TASCflow3d was developed. Results of the unsteady calculations are presented and comparisons with the measured unsteady flow field are made. As a major result, the excitation effect of the tongue region in a vaneless radial inflow turbine can be demonstrated.

  10. Force-free thin flux tubes: Basic equations and stability

    NASA Astrophysics Data System (ADS)

    Zhugzhda, Y. D.

    1996-01-01

    The thin flux tube approximation is considered for a straight, symmetrical, force-free, rigidly rotating flux tube. The derived set of equations describes tube, body sausage, and Alfvén wave modes and is valid for any values of β. The linear waves and instabilities of force-free flux tubes are considered. The comparison of approximate and exact solutions for an untwisted, nonrotating flux tube is performed. It is shown that the approximate and exact dispersion equations coincides, except the 20% discrepancy of sausage frequencies. An effective cross section is proposed to introduce the removal of this discrepancy. It makes the derived approximation correct for the force-free thin flux tube dynamics, except the detailed structure of radial eigenfunction. The dispersion of Alfvén torsional waves in a force-free tubes appears. The valve effect of one directional propagation of waves in rotating twisted tube is revealed. The current and rotational sausage instabilities of a force-free, thin flux tube are considered.

  11. Improving the radial nerve neurodynamic test: An observation of tension of the radial, median and ulnar nerves during upper limb positioning.

    PubMed

    Manvell, Joshua J; Manvell, Nicole; Snodgrass, Suzanne J; Reid, Susan A

    2015-12-01

    The radial nerve neurodynamic test (ULNT2b), used to implicate symptoms arising from the radial nerve, is proposed to selectively increase strain of the nerve without increasing strain of adjacent tissue, though this has not been established. This study aimed to determine the upper limb position that results in: (1) the greatest tension of the radial nerve and (2) the greatest difference in tension between the radial nerve and the other two major nerves of the upper limb: median and ulnar. Tension (N) of the radial, median and ulnar nerves was measured simultaneously using three buckle force transducers during seven upper limb positions in the axilla of ten embalmed whole body human cadavers (n = 20 limbs). Repeated measures analysis of variance (ANOVA) with Bonferroni post-hoc tests determined differences in tension between nerves and between limb positions. A Composite position consisting of ULNT2b (scapular depression, shoulder internal rotation, elbow extension, forearm pronation, wrist flexion) with the addition of shoulder abduction 40° and extension 25°, wrist ulnar deviation and thumb flexion demonstrated significantly greater tension of the radial nerve than any other tested position (mean tension 11.32N; 95% CI 10.25, 12.29, p < 0.01), including ULNT2b (2.20N; 1.84, 2.57; p < 0.01). Additionally, the Composite position demonstrated the greatest difference in tension between the radial and median (mean difference 4.88N; 95% CI 3.16, 6.61; p < 0.01) and radial and ulnar nerves (9.26N, 7.54, 10.99; p < 0.01). This position constitutes a biomechanically plausible test to detect neuropathic pain related to the radial nerve.

  12. Stirling Engine With Radial Flow Heat Exchangers

    NASA Technical Reports Server (NTRS)

    Vitale, N.; Yarr, George

    1993-01-01

    Conflict between thermodynamical and structural requirements resolved. In Stirling engine of new cylindrical configuration, regenerator and acceptor and rejector heat exchangers channel flow of working gas in radial direction. Isotherms in regenerator ideally concentric cylinders, and gradient of temperature across regenerator radial rather than axial. Acceptor and rejector heat exchangers located radially inward and outward of regenerator, respectively. Enables substantial increase in power of engine without corresponding increase in diameter of pressure vessel.

  13. Tolerancing a radial velocity spectrometer within Zemax

    NASA Astrophysics Data System (ADS)

    Gibson, Steven R.

    2016-08-01

    Techniques are described for tolerancing a radial velocity spectrometer system within Zemax, including: how to set up and verify the tolerancing model, performance metrics and tolerance operands used, as well as post- Zemax analysis methods. Use of the tolerancing model for various analyses will be discussed, such as: alignment sensitivity, radial velocity sensitivity, and sensitivity of the optical system to temperature changes. Tolerance results from the Keck Planet Finder project (a precision radial velocity spectrometer of asymmetric white pupil design) will be shown.

  14. Hollow Cathode With Multiple Radial Orifices

    NASA Technical Reports Server (NTRS)

    Brophy, John R.

    1992-01-01

    Improved hollow cathode serving as source of electrons has multiple radial orifices instead of single axial orifice. Distributes ion current more smoothly, over larger area. Prototype of high-current cathodes for ion engines in spacecraft. On Earth, cathodes used in large-diameter ion sources for industrial processing of materials. Radial orientation of orifices in new design causes current to be dispersed radially in vicinity of cathode. Advantageous where desireable to produce plasma more nearly uniform over wider region around cathode.

  15. Are axial and radial flow chromatography different?

    PubMed

    Besselink, Tamara; van der Padt, Albert; Janssen, Anja E M; Boom, Remko M

    2013-01-04

    Radial flow chromatography can be a solution for scaling up a packed bed chromatographic process to larger processing volumes. In this study we compared axial and radial flow affinity chromatography both experimentally and theoretically. We used an axial flow column and a miniaturized radial flow column with a ratio of 1.8 between outer and inner surface area, both with a bed height of 5 cm. The columns were packed with affinity resin to adsorb BSA. The average velocity in the columns was set equal. No difference in performance between the two columns could be observed. To gain more insight into the design of a radial flow column, the velocity profile and resin distribution in the radial flow column were calculated. Using mathematical models we found that the breakthrough performance of radial flow chromatography is very similar to axial flow when the ratio between outer and inner radius of the radial flow column is around 2. When this ratio is increased, differences become more apparent, but remain small. However, the ratio does have a significant influence on the velocity profile inside the resin bed, which directly influences the pressure drop and potentially resin compression, especially at higher values for this ratio. The choice between axial and radial flow will be based on cost price, footprint and packing characteristics. For small-scale processes, axial flow chromatography is probably the best choice, for resin volumes of at least several tens of litres, radial flow chromatography may be preferable.

  16. Isolated AA Amyloidosis of the Radial Nerve.

    PubMed

    Pérez-de la Fuente, Teresa; Fernández-Jara, Javier; Rodríguez-Urcelay, Pilar; Jiménez-Heffernan, Jose; Juárez, Ángel

    2017-09-01

    Amyloidosis affecting peripheral nerve is usually seen in primary amyloidosis. We are reporting on the case of a 74-year-old man with a 16-month history of progressive left radial nerve paralysis. Perioperative imaging detected an enlarged radial nerve in the middle-distal part of the arm. The patient had an antecedent of amyloid deposits in the lung. A radial nerve amyloidosis was suspected and confirmed with a biopsy assisted by ultrasonography, resulting in a secondary amyloidosis form. Isolated radial nerve palsy due to nerve damage by amyloidosis has been reported before, but not in AA or secondary amyloidosis.

  17. Radial vibration and ultrasonic field of a long tubular ultrasonic radiator.

    PubMed

    Shuyu, Lin; Zhiqiang, Fu; Xiaoli, Zhang; Yong, Wang; Jing, Hu

    2013-09-01

    The radial vibration of a metal long circular tube is studied analytically and its electro-mechanical equivalent circuit is obtained. Based on the equivalent circuit, the radial resonance frequency equation is derived. The theoretical relationship between the radial resonance frequency and the geometrical dimensions is studied. Finite element method is used to simulate the radial vibration and the radiated ultrasonic field and the results are compared with those from the analytical method. It is concluded that the radial resonance frequency for a solid metal rod is larger than that for a metal tube with the same outer radius. The radial resonance frequencies from the analytical method are in good agreement with those from the numerical method. Based on the acoustic field analysis, it is concluded that the long metal tube with small wall thickness is superior to that with large wall thickness in producing radial vibration and ultrasonic radiation. Therefore, it is expected to be used as an effective radial ultrasonic radiator in ultrasonic sewage treatment, ultrasonic antiscale and descaling and other ultrasonic liquid handling applications.

  18. Study on the radial vibration and acoustic field of an isotropic circular ring radiator.

    PubMed

    Lin, Shuyu; Xu, Long

    2012-01-01

    Based on the exact analytical theory, the radial vibration of an isotropic circular ring is studied and its electro-mechanical equivalent circuit is obtained. By means of the equivalent circuit model, the resonance frequency equation is derived; the relationship between the radial resonance frequency, the radial displacement amplitude magnification and the geometrical dimensions, the material property is analyzed. For comparison, numerical method is used to simulate the radial vibration of isotropic circular rings. The resonance frequency and the radial vibrational displacement distribution are obtained, and the radial radiation acoustic field of the circular ring in radial vibration is simulated. It is illustrated that the radial resonance frequencies from the analytical method and the numerical method are in good agreement when the height is much less than the radius. When the height becomes large relative to the radius, the frequency deviation from the two methods becomes large. The reason is that the exact analytical theory is limited to thin circular ring whose height must be much less than its radius.

  19. The magnetic component of geodesic acoustic modes in tokamak plasmas with a radial equilibrium electric field

    NASA Astrophysics Data System (ADS)

    Zhou, Deng

    2016-10-01

    The dispersion relation of geodesic acoustic modes with a magnetic perturbation in the tokamak plasma with an equilibrium radial electric field was derived. The dispersion relation was analyzed for very low field strength. The mode frequency decreases with increasing field strength, which is different from the electrostatic geodesic acoustic mode. There exists an m = 1 magnetic component that is very low when the radial electric field is absent. The ratio between the m = 1 and m = 2 magnetic components increases with strength of the radial electric field for low Mach numbers.

  20. Radial structures and nonlinear excitation of Geodesic Acoustic Modes

    NASA Astrophysics Data System (ADS)

    Chen, Liu; Zonca, Fulvio

    2007-11-01

    In this paper, we show that GAMs constitute a continuous spectrum due to radial inhomogeneities. The existence of singular layer, thus, suggests linear mode conversion to short-wavelength kinetic GAM (KGAM) via finite ion Larmor radii. This result is demonstrated by derivations of the GAM mode structure and dispersion relation in the singular layer. At the lowest order in krρi, with kr the radial wave vector and ρi the ion Larmor radius, the well known kinetic dispersion relation of GAM is recovered. At the next relevant order, O(kr^2ρi^2), we show that KGAM propagates in the low-temperature and/or high safety-factor domain; i.e., typically, radially outward, and a corresponding damping rate is derived. In this work, we also show that, while KGAM is linearly stable due to ion Landau damping, it can be nonlinearly excited by finite-amplitude DW turbulence via 3-wave parametric interactions. The resultant 3-wave system exhibits the typical prey-predator self-regulatory dynamics.

  1. Nonlinear plasma vortices in the Jupiter magnetosphere and radial diffusion in the radiation belt

    NASA Astrophysics Data System (ADS)

    Kropotkin, A. P.; Mozzhukhina, A. R.

    Within the framework of representations about two-dimensional vortex character of hydrodynamic turbulence in Jo torus linked with the development of rearrangement (flute) instability of torus plasma, nonlinear equations describing such disturbances with regard to ionospheric conductivity effect are derived. Evaluations of chacteristic size of a vortex and value of electric field disturbances are found. Energetic particle radial diffusion coefficient in the Jo torus region is calculated, radial diffusion equation with model losses is solved.

  2. Tuning porosity and radial mechanical properties of DNA origami nanotubes via crossover design

    NASA Astrophysics Data System (ADS)

    Ma, Zhipeng; Kawai, Kentaro; Hirai, Yoshikazu; Tsuchiya, Toshiyuki; Tabata, Osamu

    2017-06-01

    DNA origami nanotubes are utilized as structural platforms for the fabrication of various micro/nanosystems for drug delivery, optical or biological sensing, and even nanoscale robots. Their radial structural and mechanical properties, which play a crucial role in the effective use of micro/nanosystems, have not been fully studied. In particular, the effects of crossovers, which are basic structures for rationally assembling double-stranded DNA (dsDNA) helices into a nanotube configuration, have not yet been characterized experimentally. To investigate the effects of crossovers on the porosity and the radial mechanical properties of DNA origami nanotubes, we fabricated a DNA origami nanotube with varied crossover designs along the nanotube axis. The radial geometry of the DNA origami nanotube is experimentally characterized by both atomic force microscopy (AFM) and electron cryomicroscopy (cryo-EM). Moreover, the radial mechanical properties of the DNA origami nanotube including the radial modulus are directly measured by force-distance-based AFM. These measurements reveal that the porosity and the radial modulus of DNA origami nanotubes can be tuned by adjusting the crossover design, which enables the optimal design and construction of DNA origami nanostructures for various applications.

  3. Parameterization of backbone flexibility in a coarse-grained force field for proteins (COFFDROP) derived from all-atom explicit-solvent molecular dynamics simulations of all possible two-residue peptides

    PubMed Central

    Frembgen-Kesner, Tamara; Andrews, Casey T.; Li, Shuxiang; Ngo, Nguyet Anh; Shubert, Scott A.; Jain, Aakash; Olayiwola, Oluwatoni; Weishaar, Mitch R.; Elcock, Adrian H.

    2015-01-01

    Recently, we reported the parameterization of a set of coarse-grained (CG) nonbonded potential functions, derived from all-atom explicit-solvent molecular dynamics (MD) simulations of amino acid pairs, and designed for use in (implicit-solvent) Brownian dynamics (BD) simulations of proteins; this force field was named COFFDROP (COarse-grained Force Field for Dynamic Representations Of Proteins). Here, we describe the extension of COFFDROP to include bonded backbone terms derived from fitting to results of explicit-solvent MD simulations of all possible two-residue peptides containing the 20 standard amino acids, with histidine modeled in both its protonated and neutral forms. The iterative Boltzmann inversion (IBI) method was used to optimize new CG potential functions for backbone-related terms by attempting to reproduce angle, dihedral and distance probability distributions generated by the MD simulations. In a simple test of the transferability of the extended force field, the angle, dihedral and distance probability distributions obtained from BD simulations of 56 three-residue peptides were compared to results from corresponding explicit-solvent MD simulations. In a more challenging test of the COFFDROP force field, it was used to simulate eight intrinsically disordered proteins and was shown to quite accurately reproduce the experimental hydrodynamic radii (Rhydro), provided that the favorable nonbonded interactions of the force field were uniformly scaled downwards in magnitude. Overall, the results indicate that the COFFDROP force field is likely to find use in modeling the conformational behavior of intrinsically disordered proteins and multi-domain proteins connected by flexible linkers. PMID:26574429

  4. Parametrization of Backbone Flexibility in a Coarse-Grained Force Field for Proteins (COFFDROP) Derived from All-Atom Explicit-Solvent Molecular Dynamics Simulations of All Possible Two-Residue Peptides.

    PubMed

    Frembgen-Kesner, Tamara; Andrews, Casey T; Li, Shuxiang; Ngo, Nguyet Anh; Shubert, Scott A; Jain, Aakash; Olayiwola, Oluwatoni J; Weishaar, Mitch R; Elcock, Adrian H

    2015-05-12

    Recently, we reported the parametrization of a set of coarse-grained (CG) nonbonded potential functions, derived from all-atom explicit-solvent molecular dynamics (MD) simulations of amino acid pairs and designed for use in (implicit-solvent) Brownian dynamics (BD) simulations of proteins; this force field was named COFFDROP (COarse-grained Force Field for Dynamic Representations Of Proteins). Here, we describe the extension of COFFDROP to include bonded backbone terms derived from fitting to results of explicit-solvent MD simulations of all possible two-residue peptides containing the 20 standard amino acids, with histidine modeled in both its protonated and neutral forms. The iterative Boltzmann inversion (IBI) method was used to optimize new CG potential functions for backbone-related terms by attempting to reproduce angle, dihedral, and distance probability distributions generated by the MD simulations. In a simple test of the transferability of the extended force field, the angle, dihedral, and distance probability distributions obtained from BD simulations of 56 three-residue peptides were compared to results from corresponding explicit-solvent MD simulations. In a more challenging test of the COFFDROP force field, it was used to simulate eight intrinsically disordered proteins and was shown to quite accurately reproduce the experimental hydrodynamic radii (Rhydro), provided that the favorable nonbonded interactions of the force field were uniformly scaled downward in magnitude. Overall, the results indicate that the COFFDROP force field is likely to find use in modeling the conformational behavior of intrinsically disordered proteins and multidomain proteins connected by flexible linkers.

  5. Iatrogenic radial neck fracture on closed reduction of elbow dislocation.

    PubMed

    Ellanti, Prasad; O'Farrell, Dermot

    2013-11-01

    Traumatic dislocation of the elbow is rare in children and can most often be managed in the emergency department using procedural sedation and closed reduction with good functional outcome. Radiographs must be evaluated for associated avulsions and fractures around the elbow. We present the case of a 14-year-old girl who sustained a fracture of the radial neck subsequent to repeated attempts at closed reduction of a pure posterior elbow dislocation that was missed on postreduction radiographs. Careful use of reduction techniques and avoidance of repeated forceful manipulations is emphasized.

  6. Hydrodynamic effects in a misaligned radial face seal

    NASA Technical Reports Server (NTRS)

    Etsion, I.

    1977-01-01

    Hydrodynamic effects in a flat seal having an angular misalignment are analyzed, taking into account the radial variation in seal clearance. An analytical solution for axial force, restoring moment, and transverse moment is presented that covers the whole range from zero to full angular misalignment. Both low pressure seals with cavitating flow and high pressure seals with full fluid film are considered. Strong coupling is demonstrated between angular misalignment and transverse moment which leads the misalignment vector by 90 degrees. This transverse moment, which is entirely due to hydrodynamic effects, is a significant factor in the seal operating mechanism.

  7. Radial q-space sampling for DSI.

    PubMed

    Baete, Steven H; Yutzy, Stephen; Boada, Fernando E

    2016-09-01

    Diffusion spectrum imaging (DSI) has been shown to be an effective tool for noninvasively depicting the anatomical details of brain microstructure. Existing implementations of DSI sample the diffusion encoding space using a rectangular grid. Here we present a different implementation of DSI whereby a radially symmetric q-space sampling scheme for DSI is used to improve the angular resolution and accuracy of the reconstructed orientation distribution functions. Q-space is sampled by acquiring several q-space samples along a number of radial lines. Each of these radial lines in q-space is analytically connected to a value of the orientation distribution functions at the same angular location by the Fourier slice theorem. Computer simulations and in vivo brain results demonstrate that radial diffusion spectrum imaging correctly estimates the orientation distribution functions when moderately high b-values (4000 s/mm2) and number of q-space samples (236) are used. The nominal angular resolution of radial diffusion spectrum imaging depends on the number of radial lines used in the sampling scheme, and only weakly on the maximum b-value. In addition, the radial analytical reconstruction reduces truncation artifacts which affect Cartesian reconstructions. Hence, a radial acquisition of q-space can be favorable for DSI. Magn Reson Med 76:769-780, 2016. © 2015 Wiley Periodicals, Inc. © 2015 Wiley Periodicals, Inc.

  8. Differentiating common causes of radial wrist pain.

    PubMed

    Shuaib, Waqas; Mohiuddin, Zia; Swain, Freddie R; Khosa, Faisal

    2014-09-01

    Radial wrist pain is a common patient complaint with a broad differential. Because treatment and prognosis differ, determining the underlying cause is key. This article reviews a case of intersection syndrome and compares it to other causes of radial wrist pain.

  9. Radial velocities in three fields along the southern galactic equator

    NASA Astrophysics Data System (ADS)

    Denoyelle, J.

    1987-09-01

    A list of radial velocities for 764 stars is given for three fields in the Vela-Carina region of the Galaxy. They were obtained from GPO-plates taken at La Silla and reduced following Fehrenbach's method. Slit-spectra were collected with the 152 cm-spectrographic telescope at La Silla, to derive an accurate radial velocity for a sufficient number of calibration stars: out of the 29 stars, 26 had no formerly published value. The global motions of 10 to 14 km/s can be considered as normal on the basis of galactic rotation. Some stars however show high velocities. The case of HD 81471 (Sp type A7 Iab) suggest that a detailed study of this star is to be recommended.

  10. New radial pulsation constants for the Beta Cephei variables

    NASA Astrophysics Data System (ADS)

    Shobbrook, R. R.

    1985-05-01

    Recent new calibrations of luminosities, temperatures and bolometric corrections for B stars in terms of the β index and the Strömgren parameter c0 have necessitated the recalculation of the radial pulsation constants, Q, for the β Cephei (of β Canis Majoris) variable stars. Corrections for the effect of binaries on the absolute magnitudes, derived both from the luminosity calibration and from the mean distance moduli of those variables in clusters, are calculated in an Appendix. The mean value of Q, although determined from absolute magnitudes which are about 0.4 mag fainter than those from previous calibrations of the β index, still suggests that the majority of the variables are pulsating in the first overtone radial mode, as have most investigations in recent years.

  11. [Optimization of gel radial diffusion method for serum immunoglobulin analysis].

    PubMed

    Gerasimov, I G; Zorkova, E V

    2002-07-01

    Serum IgA, IgM, and IgG were measured by radial immunodiffusion in gel; immunoglobulin concentrations correlated with the diameter of their diffusion. A theoretically-based equation was derived; use of this equation will help estimate serum Ig content without plotting a calibration curve by the square diameter of the immunodiffusion ring of undiluted reference serum in a wide range of concentrations (0.3-3 mg/ml for IgA and IgM and 2-18 mg/ml for IgG). This modification of measuring serum immunoglobulins by radial immunodiffusion in gel is as accurate as other methods, but is reagent- and time-saving.

  12. The Radially Symmetric Euler Equations as an Exterior Differential System

    NASA Astrophysics Data System (ADS)

    Baty, Roy; Ramsey, Scott; Schmidt, Joseph

    2016-11-01

    This work develops the Euler equations as an exterior differential system in radially symmetric coordinates. The Euler equations are studied for unsteady, compressible, inviscid fluids in one-dimensional, converging flow fields with a general equation of state. The basic geometrical constructions (for example, the differential forms, tangent planes, jet space, and differential ideal) used to define and analyze differential equations as systems of exterior forms are reviewed and discussed for converging flows. Application of the Frobenius theorem to the question of the existence of solutions to radially symmetric converging flows is also reviewed and discussed. The exterior differential system is further applied to derive and analyze the general family of characteristic vector fields associated with the one-dimensional inviscid flow equations.

  13. STARSPOT JITTER IN PHOTOMETRY, ASTROMETRY, AND RADIAL VELOCITY MEASUREMENTS

    SciTech Connect

    Makarov, V. V.; Beichman, C. A.; Lebreton, J.; Malbet, F.; Catanzarite, J. H.; Shao, M.; Fischer, D. A.

    2009-12-10

    Analytical relations are derived for the amplitude of astrometric, photometric, and radial velocity (RV) perturbations caused by a single rotating spot. The relative power of the starspot jitter is estimated and compared with the available data for kappa{sup 1} Ceti and HD 166435, as well as with numerical simulations for kappa{sup 1} Ceti and the Sun. A Sun-like star inclined at i = 90 deg. at 10 pc is predicted to have an rms jitter of 0.087 muas in its astrometric position along the equator, and 0.38 m s{sup -1} in radial velocities. If the presence of spots due to stellar activity is the ultimate limiting factor for planet detection, the sensitivity of SIM Lite to Earth-like planets in habitable zones is about an order of magnitude higher than the sensitivity of prospective ultra-precise RV observations of nearby stars.

  14. Computer Simulation of Radial Immunodiffusion

    PubMed Central

    Trautman, Rodes

    1972-01-01

    Theories of diffusion with chemical reaction are reviewed as to their contributions toward developing an algorithm needed for computer simulation of immunodiffusion. The Spiers-Augustin moving sink and the Engelberg stationary sink theories show how the antibody-antigen reaction can be incorporated into boundary conditions of the free diffusion differential equations. For this, a stoichiometric precipitate was assumed and the location of precipitin lines could be predicted. The Hill simultaneous linear adsorption theory provides a mathematical device for including another special type of antibody-antigen reaction in antigen excess regions of the gel. It permits an explanation for the lowered antigen diffusion coefficient, observed in the Oudin arrangement of single linear diffusion, but does not enable prediction of the location of precipitin lines. The most promising mathematical approach for a general solution is implied in the Augustin alternating cycle theory. This assumes the immunodiffusion process can be evaluated by alternating computation cycles: free diffusion without chemical reaction and chemical reaction without diffusion. The algorithm for the free diffusion update cycle, extended to both linear and radial geometries, is given in detail since it was based on gross flow rather than more conventional expressions in terms of net flow. Limitations on the numerical integration process using this algorithm are illustrated for free diffusion from a cylindrical well. PMID:4629869

  15. Radial Correlations Between Two Quarks

    NASA Astrophysics Data System (ADS)

    Green, A. M.; Koponen, J.; Pennanen, P.; Michael, C.

    2002-04-01

    In nuclear many-body problems the short-range correlation between two nucleons is well described by the corresponding correlation in the two-body problem. Therefore, as a first step in any attempt at an analogous description of many-quark systems, it is necessary to know the two-quark correlation. With this in mind, we study the light quark distribution in a heavy-light meson with a static heavy quark. The charge and matter radial distributions of these heavy-light mesons are measured on a lattice with a light quark mass about that of the strange quark. Both distributions can be well fitted upto r ≈ 0.7 fm with the exponential form wi2 (r), where Wi(r) = A exp(-r/ri). For the charge(c) and matter(m) distributions rc ≈ 0.32(2)fm and rm ≈ 0.24(2)fm. We also discuss the normalisation of the total charge (defined to be unity in the continuum limit) and matter integrated over all space, finding 1.30(5) and 0.4(1) respectively for a lattice spacing ≈ 0.17 fm.

  16. Radial keratotomy associated endothelial degeneration

    PubMed Central

    Moshirfar, Majid; Ollerton, Andrew; Semnani, Rodmehr T; Hsu, Maylon

    2012-01-01

    Purpose To describe the presentation and clinical course of eyes with a history of radial keratotomy (RK) and varying degrees of endothelial degeneration. Methods Retrospective case series were used. Results Thirteen eyes (seven patients) were identified with clinical findings of significant guttata and a prior history of RK. The mean age of presentation for cornea evaluation was 54.3 years (range: 38–72 years), averaging 18.7 years (range: 11–33 years) after RK. The presentation of guttata varied in degree from moderate to severe. Best corrected visual acuity (BCVA) ranged from 20/25 to 20/80. All patients had a history of bilateral RK, except one patient who did not develop any guttata in the eye without prior RK. No patients reported a family history of Fuch’s Dystrophy. One patient underwent a penetrating keratoplasty in one eye and a Descemet’s stripping automated endothelial keratoplasty (DSAEK) in the other eye. Conclusions RK may induce a spectrum of endothelial degeneration. In elderly patients, the findings of guttata may signify comorbid Fuch’s dystrophy in which RK incisions could potentially hasten endothelial decomposition. In these select patients with stable cornea topography and prior RK, DSAEK may successfully treat RK endothelial degeneration. PMID:22347792

  17. Radial keratotomy associated endothelial degeneration.

    PubMed

    Moshirfar, Majid; Ollerton, Andrew; Semnani, Rodmehr T; Hsu, Maylon

    2012-01-01

    To describe the presentation and clinical course of eyes with a history of radial keratotomy (RK) and varying degrees of endothelial degeneration. Retrospective case series were used. Thirteen eyes (seven patients) were identified with clinical findings of significant guttata and a prior history of RK. The mean age of presentation for cornea evaluation was 54.3 years (range: 38-72 years), averaging 18.7 years (range: 11-33 years) after RK. The presentation of guttata varied in degree from moderate to severe. Best corrected visual acuity (BCVA) ranged from 20/25 to 20/80. All patients had a history of bilateral RK, except one patient who did not develop any guttata in the eye without prior RK. No patients reported a family history of Fuch's Dystrophy. One patient underwent a penetrating keratoplasty in one eye and a Descemet's stripping automated endothelial keratoplasty (DSAEK) in the other eye. RK may induce a spectrum of endothelial degeneration. In elderly patients, the findings of guttata may signify comorbid Fuch's dystrophy in which RK incisions could potentially hasten endothelial decomposition. In these select patients with stable cornea topography and prior RK, DSAEK may successfully treat RK endothelial degeneration.

  18. Impact of radial artery cannulation for coronary angiography and angioplasty on radial artery function.

    PubMed

    Burstein, Jason M; Gidrewicz, Dominica; Hutchison, Stuart J; Holmes, Kate; Jolly, Sanjit; Cantor, Warren J

    2007-02-15

    The radial artery is commonly used as a conduit in coronary artery bypass grafting. No data exist on the effects of radial sheath insertion on radial artery function. Because many patients considered for coronary artery bypass grafting have had previous radial procedures, it is important to understand any effects radial sheath insertion may have on radial artery function. Twenty-two patients who underwent elective coronary angiography or angioplasty with a 6Fr sheath through the right radial artery were studied. Radial artery function was assessed using ultrasound to measure flow-mediated dilation (FMD). Reactive hyperemia was produced by 5-minute cuff inflation on the arm to suprasystolic pressures. Radial artery diameter was measured at rest and 1 minute after cuff deflation. FMD was expressed as percent change in radial diameter compared with at rest. In all cases, the left radial artery was studied as a control. Patients were studied before sheath insertion, immediately after sheath insertion, and 6 weeks after sheath insertion. The FMD of the cannulated arm was 13.2% before sheath insertion versus 3.6% immediately after sheath insertion (p <0.01) and 0.2% (p <0.01) 9 weeks after sheath insertion. In contrast, there were no significant changes in the noncannulated arm at either time point. In conclusion, radial artery sheath insertion for coronary angiography or angioplasty results in immediate and persistent blunting of FMD, suggesting severe vasomotor dysfunction. Radial artery sheath insertion has important effects on radial artery function that must be considered when selecting radial conduits for coronary artery bypass grafting.

  19. Spectrographs for the Measurement of Radial Velocities

    NASA Astrophysics Data System (ADS)

    Baranne, A.

    A radial-velocity measurement derives from a shift in position of spectral features at the focus of a spectrographic instrument. We do not often think about how small these shifts are. It is not generally appreciated that the accuracy to which this shift must be measured is a tiny fraction of a pixel. Or, if we prefer to calculate in microns a surprising minuteness. What precautions should we be taking for the measurement of such small shifts? It is true that, thanks to computers, modern reduction methods allows us to correct for a wide variety of pertubations, provided that these are foreseen and understood; but such reduction procedures will give the best results if such pertubations are kept very small. We must therefore analyse these pertubations and think about how we can control them. The correlation method initiated in its modern form by Roger Griffin, and which we developed further with an optical mask in CORAVEL twenty-five years ago and more recently with a numerical mask in ELODIE, has demonstrated its power. In terms of these methods, the problem of high precision is to improve the correlation peak. Can this be done? Does the correlation method allow us to distinguish the overall radial velocity of the object from possible distortions of the lines? This is certainly a major problem which must be solved. The luminous efficiency of high-precision spectrographs is low. If the use of an optical fibre with scrambling for feeding the spectrograph seems inevitable to us today, it seems to me that the transmission of this system can be considerably improved by a better choice of the F-ratio of the image beam of the telescope which is to be matched with that of the spectrograph. This problem, common to all spectrographs, could be resolved with a specialised focal-plane instrument, giving a much greater than usual F-ratio, resulting in a simplification of the spectrograph optics, and hence an improvement in transmission and a serious decrease in size (which is

  20. On the radial width of CMEs between 0.1 and 0.4 AU

    NASA Astrophysics Data System (ADS)

    Savani, N. P.; Forsyth, R. J.; Rouillard, A. P.; Owens, M. J.; Davies, J. A.

    2009-04-01

    The launch of the two STEREO spacecraft in 2006 has heralded a new era of opportunities to make remote observations of interplanetary coronal mass ejections (ICMEs). An example CME on the 16th February 2008 with an approximately circular cross section was tracked through successive images obtained by the Heliospheric Imager (HI) instrument onboard the STEREO-A spacecraft. The cylindrical nature of force-free constant alpha flux ropes is used to determine the radial size of the CME. The radial velocity and longitude of propagation are determined. With these parameters known, the radial size is calculated from the images taking projection effects into account. A power law is obtained for the resulting radial width behaviour with heliocentric distance as the CME travels between 0.1 and 0.4 AU. We compare our results to those obtained in published studies based on in-situ spacecraft observations of ICMEs between 0.3 and 1.0 AU.

  1. Thermal convection in a cylindrical annulus under a combined effect of the radial and vertical gravity

    NASA Astrophysics Data System (ADS)

    Meyer, Antoine; Jongmanns, Marcel; Meier, Martin; Egbers, Christoph; Mutabazi, Innocent

    2017-01-01

    The stability of the flow of a dielectric fluid confined in a cylindrical annulus submitted to a radial temperature gradient and a radial electric field is investigated theoretically and experimentally. The radial temperature gradient induces a vertical Archimedean buoyancy and a radial dielectrophoretic buoyancy. These two forces intervene simultaneously in the destabilization of the flow, leading to the occurrence of four types of modes depending on the relative intensity of these two buoyancies and on the fluid's properties: hydrodynamic and thermal modes that are axisymmetric and oscillatory, stationary columnar modes and electric modes which are stationary and non-axisymmetric modes. Experiments performed in a parabolic flight show the existence of non-axisymmetric modes that should be either columnar or helicoidal vortices.

  2. SpicyNodes: radial layout authoring for the general public.

    PubMed

    Douma, Michael; Ligierko, Grzegorz; Ancuta, Ovidiu; Gritsai, Pavel; Liu, Sean

    2009-01-01

    Trees and graphs are relevant to many online tasks such as visualizing social networks, product catalogs, educational portals, digital libraries, the semantic web, concept maps and personalized information management. SpicyNodes is an information-visualization technology that builds upon existing research on radial tree layouts and graph structures. Users can browse a tree, clicking from node to node, as well as successively viewing a node, immediately related nodes and the path back to the "home" nodes. SpicyNodes' layout algorithms maintain balanced layouts using a hybrid mixture of a geometric layout (a succession of spanning radial trees) and force-directed layouts to minimize overlapping nodes, plus several other improvements over prior art. It provides XML-based API and GUI authoring tools. The goal of the SpicyNodes project is to implement familiar principles of radial maps and focus+context with an attractive and inviting look and feel in an open system that is accessible to virtually any Internet user.

  3. A Determination of the Benefits Derived by the Air Force from Providing Air Force Officers in the Logistics Field with Graduate Degrees in the Business Area from Civilian Graduate Institutions.

    ERIC Educational Resources Information Center

    Chamberlin, Brian; Smith, Richard A.

    This thesis is concerned with what benefits the Air Force receives from sending logistics officers to civilian graduate institutions (CID). Additionally, the authors wanted to find how CID graduates fare as compared with graduates of the Graduate Logistics Management (GL). Three samples gathered were for CID graduates, the non-degree group…

  4. A Determination of the Benefits Derived by the Air Force from Providing Air Force Officers in the Logistics Field with Graduate Degrees in the Business Area from Civilian Graduate Institutions.

    ERIC Educational Resources Information Center

    Chamberlin, Brian; Smith, Richard A.

    This thesis is concerned with what benefits the Air Force receives from sending logistics officers to civilian graduate institutions (CID). Additionally, the authors wanted to find how CID graduates fare as compared with graduates of the Graduate Logistics Management (GL). Three samples gathered were for CID graduates, the non-degree group…

  5. Continuous time random walks for non-local radial solute transport

    NASA Astrophysics Data System (ADS)

    Dentz, Marco; Kang, Peter K.; Le Borgne, Tanguy

    2015-08-01

    This study formulates and analyzes continuous time random walk (CTRW) models in radial flow geometries for the quantification of non-local solute transport induced by heterogeneous flow distributions and by mobile-immobile mass transfer processes. To this end we derive a general CTRW framework in radial coordinates starting from the random walk equations for radial particle positions and times. The particle density, or solute concentration is governed by a non-local radial advection-dispersion equation (ADE). Unlike in CTRWs for uniform flow scenarios, particle transition times here depend on the radial particle position, which renders the CTRW non-stationary. As a consequence, the memory kernel characterizing the non-local ADE, is radially dependent. Based on this general formulation, we derive radial CTRW implementations that (i) emulate non-local radial transport due to heterogeneous advection, (ii) model multirate mass transfer (MRMT) between mobile and immobile continua, and (iii) quantify both heterogeneous advection in a mobile region and mass transfer between mobile and immobile regions. The expected solute breakthrough behavior is studied using numerical random walk particle tracking simulations. This behavior is analyzed by explicit analytical expressions for the asymptotic solute breakthrough curves. We observe clear power-law tails of the solute breakthrough for broad (power-law) distributions of particle transit times (heterogeneous advection) and particle trapping times (MRMT model). The combined model displays two distinct time regimes. An intermediate regime, in which the solute breakthrough is dominated by the particle transit times in the mobile zones, and a late time regime that is governed by the distribution of particle trapping times in immobile zones. These radial CTRW formulations allow for the identification of heterogeneous advection and mobile-immobile processes as drivers of anomalous transport, under conditions relevant for field tracer

  6. Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio

    PubMed Central

    Kruyt, Jan W.; van Heijst, GertJan F.; Altshuler, Douglas L.; Lentink, David

    2015-01-01

    Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack and vice versa at high angle of attack. PMID:25788539

  7. The Radial Variation of H I Velocity Dispersions in Dwarfs and Spirals

    NASA Astrophysics Data System (ADS)

    Ianjamasimanana, R.; de Blok, W. J. G.; Walter, Fabian; Heald, George H.; Caldú-Primo, Anahi; Jarrett, Thomas H.

    2015-08-01

    Gas velocity dispersions provide important diagnostics of the forces counteracting gravity to prevent collapse of the gas. We use the 21 cm line of neutral atomic hydrogen (H i) to study H i velocity dispersion ({σ }{{H} {{I}}}) and H i phases as a function of galaxy morphology in 22 galaxies from The H i Nearby Galaxy Survey. We stack individual H i velocity profiles and decompose them into broad and narrow Gaussian components. We study the H i velocity dispersion and the H i surface density, {{{Σ }}}{{H} {{I}}}, as a function of radius. For spirals, the velocity dispersions of the narrow and broad components decline with radius and their radial profiles are well described by an exponential function. For dwarfs, however, the profiles are much flatter. The single Gaussian dispersion profiles are, in general, flatter than those of the narrow and broad components. In most cases, the dispersion profiles in the outer disks do not drop as fast as the star formation profiles derived in the literature. This indicates the importance of other energy sources in driving {σ }{{H} {{I}}} in the outer disks. The radial surface density profiles of spirals and dwarfs are similar. The surface density profiles of the narrow component decline more steeply than those of the broad component, but not as steep as what was found previously for the molecular component. As a consequence, the surface density ratio between the narrow and broad components, an estimate of the mass ratio between cold H i and warm H i, tends to decrease with radius. On average, this ratio is lower in dwarfs than in spirals. This lack of a narrow, cold H i component in dwarfs may explain their low star formation activity.

  8. Power reduction and the radial limit of stall delay in revolving wings of different aspect ratio.

    PubMed

    Kruyt, Jan W; van Heijst, GertJan F; Altshuler, Douglas L; Lentink, David

    2015-04-06

    Airplanes and helicopters use high aspect ratio wings to reduce the power required to fly, but must operate at low angle of attack to prevent flow separation and stall. Animals capable of slow sustained flight, such as hummingbirds, have low aspect ratio wings and flap their wings at high angle of attack without stalling. Instead, they generate an attached vortex along the leading edge of the wing that elevates lift. Previous studies have demonstrated that this vortex and high lift can be reproduced by revolving the animal wing at the same angle of attack. How do flapping and revolving animal wings delay stall and reduce power? It has been hypothesized that stall delay derives from having a short radial distance between the shoulder joint and wing tip, measured in chord lengths. This non-dimensional measure of wing length represents the relative magnitude of inertial forces versus rotational accelerations operating in the boundary layer of revolving and flapping wings. Here we show for a suite of aspect ratios, which represent both animal and aircraft wings, that the attachment of the leading edge vortex on a revolving wing is determined by wing aspect ratio, defined with respect to the centre of revolution. At high angle of attack, the vortex remains attached when the local radius is shorter than four chord lengths and separates outboard on higher aspect ratio wings. This radial stall limit explains why revolving high aspect ratio wings (of helicopters) require less power compared with low aspect ratio wings (of hummingbirds) at low angle of attack and vice versa at high angle of attack.

  9. Mimicking photoisomerisation of azo-materials by a force field switch derived from nonadiabatic ab initio simulations: Application to photoswitchable helical foldamers in solution

    NASA Astrophysics Data System (ADS)

    Böckmann, Marcus; Braun, Sebastian; Doltsinis, Nikos L.; Marx, Dominik

    2013-08-01

    A force field to induce isomerisation of photoswitchable azobenzene groups embedded in molecular materials has been developed in the framework of force field molecular dynamics simulations. A molecular mechanics switching potential has been tuned so as to reproduce both the correct photoisomerisation timescale and mechanism that has been generated by reference nonadiabatic ab initio molecular dynamics. As a first application, we present a force field molecular dynamics study of a prototype photoswitchable foldamer in acetonitrile as solvent. Our analyses reveal that the photoisomerisation of the azobenzene unit embedded in the foldamer occurs via the so-called NN-twist mechanism, and that there exist several distinct unfolding channels for the helix that could be exploited in novel applications of photoresponsive materials.

  10. State-dependent radial elasticity of attached cross-bridges in single skinned fibres of rabbit psoas muscle.

    PubMed Central

    Xu, S; Brenner, B; Yu, L C

    1993-01-01

    1. In a single skinned fibre of rabbit psoas muscle, upon attachment of cross bridges to actin in the presence of ADP or pyrophosphate (PPi), the separation between the contractile filaments, as determined by equatorial X-ray diffraction, is found to decrease, suggesting that force is generated in the radial direction. 2. The single muscle fibres were subjected to compression by 0-8% of dextran T500. The changes in lattice spacings by dextran compression were compared with changes induced by cross-bridge attachment to actin. Based on this comparison, the magnitude and the direction of the radial force generated by the attached cross-bridges were estimated. The radial cross-bridge force varied with filament separation, and the magnitude of the radial cross-bridge force reached as high as the maximal axial force produced during isometric contraction. 3. One key parameter of the radial elasticity, i.e. the equilibrium spacing where the radial force is zero, was found to depend on the ligand bound to the myosin head. In the presence of ADP, the equilibrium spacing was 36 nm. In the presence of MgPPi the equilibrium spacing shifted to 35 nm and Ca2+ had little effect on the equilibrium spacing. 4. The equilibrium spacing was independent of the fraction of cross-bridges attached to actin. The fraction of cross-bridges attached in rigor was modulated from 100% to close to 0% by adding up to 10 mM of ATP gamma S in the rigor solution. The lattice spacing remained at 38 nm, the equilibrium spacing for nucleotide-free cross-bridges at mu = 170 mM. 5. Radial force generated by cross-bridges in rigor at large lattice spacings (38 nm < or = d10 < or = 46 nm) appeared to vary linearly with lattice spacing. 6. The titration of ATP gamma S to fibres in rigor provided a correlation between the radial stiffness of the nucleotide-free cross-bridges and the equatorial intensities. The relation between the equatorial intensity ratio I11/I10 and radial stiffness appeared to be

  11. Slope Stability Analysis Using Radial Slices: A Mathematical Model

    NASA Astrophysics Data System (ADS)

    Kumar, Gyan Prakash; Das, Adarsha; Rai, Rajesh; Jaiswal, Ashok

    2015-10-01

    In this paper, a mathematical model has been formulated for calculating the factor of safety of a slope. Corresponding computer code has also been developed. Limit equilibrium method (moment equilibrium) has been adopted for calculating the net resulting driving and resisting forces. The probable slip circle region has been divided into radial slices for the simulation process. In this approach, the inter-slice shear forces are zero. Thus, the calculation process becomes simpler as compared to that with vertical slices. The slope stability analyses were done. Validation of the present program was done with existing limit equilibrium based methods. Various models were prepared and analysed with varying geometry and soil strength parameters. These models were also analysed with other limit equilibrium methods like Bishop, Janbu and Spencer method. The results were found to be in agreement with the results of other limit equilibrium methods for the same dump soil properties and slope parameters.

  12. Superscattering pattern shaping for radially anisotropic nanowires

    NASA Astrophysics Data System (ADS)

    Liu, Wei

    2017-08-01

    We achieve efficient shaping of superscattering by radially anisotropic nanowires relying on resonant multipolar interferences. It is shown that the radial anisotropy of refractive index can be employed to resonantly overlap electric and magnetic multipoles of various orders, and as a result, effective superscattering with different engineered angular patterns can be obtained. We further demonstrate that such superscattering shaping relying on unusual radial anisotropy parameters can be directly realized with isotropic multilayered nanowires, which may shed new light on much fundamental research and various applications related to scattering particles.

  13. A comparison of far-field properties of radial noncanonical vortex airy beam arrays and radial noncanonical vortex Gaussian beam arrays

    NASA Astrophysics Data System (ADS)

    Cheng, Ke; Jiao, Liyang; Zhong, Xianqiong

    2016-05-01

    Based on the vector angular spectrum representation and stationary phase method, the analytical far-field vectorial expressions of radial noncanonical vortex Airy beam arrays (NVAiBAs) and radial noncanonical vortex Gaussian beam arrays (NVGBAs) are derived, and used to investigate their far-field vectorial properties, e.g. center optical vortices and energy fluxes of these corresponding beams, where the effect of noncanonical strength, topological charge, initial phase index and the number of beamlet on far-field vectorial properties of these corresponding beams is emphasized, respectively. The results show that the topological charge of center optical vortices in the far field is equal to initial phase index for the case of the radial NVAiBAs, whereas for radial NVGBAs the topological charge not only lies on initial phase index, but also is closely related to the odevity and sign of optical vortices embedded in beamlet, where mathematical analysis is made to explain the topological charge of center optical vortices, and the limitation of the number of beamlet to the topological charge of center optical vortices is also discussed. In addition, energy fluxes of radial NVAiBAs and NVGBAs exhibit different space orientations by controlling noncancial strength and present larger dark zones by increasing topological charge of beamlet, respectively. Finally, the relationship between the center optical vortices and energy fluxes of radial NVAiBAs and NVGBAs in even or odd N beamlets is also revealed, respectively.

  14. Electron motion analysis of a radial-radiated electron beam in a radial-line drift tube with finite magnetic field conducted

    NASA Astrophysics Data System (ADS)

    Dang, Fangchao; Zhang, Xiaoping; Zhong, Huihuang

    2017-02-01

    Radial-radiated electron beam is widely employed in radial-line structure microwave devices. The quality of the electron beam has a crucial effect on the operating performance of these devices. This paper analyzes theoretically this electron motion in a radial-line drift tube with finite magnetic field conducted. The beam width, spatial period, and fluctuation amplitude are quantitatively analyzed with different beam current parameters. By the particle-in-cell simulation, we examine the theoretical analysis under the condition of a designed realistic coil configuration. It indicates that the derived beam envelope function is capable of predicting the radial-radiated beam trajectory approximately. Meanwhile, it is found that the off-axial z-direction magnetic field, in spite of its greatly slight amplitude, is also one necessary consideration for the propagation characteristic of the radial-radiated electron beam. Furthermore, the presented electron motion analysis may be instructive for the design of the electronic optical system of the radial-line structure microwave devices.

  15. SCM-Forcing Data

    SciTech Connect

    Xie, Shaocheng; Tang, Shuaiqi; Zhang, Yunyan; Zhang, Minghua

    2016-07-01

    Single-Column Model (SCM) Forcing Data are derived from the ARM facility observational data using the constrained variational analysis approach (Zhang and Lin 1997 and Zhang et al., 2001). The resulting products include both the large-scale forcing terms and the evaluation fields, which can be used for driving the SCMs and Cloud Resolving Models (CRMs) and validating model simulations.

  16. The galactic gamma-ray distribution: Implications for galactic structure and the radial cosmic ray gradient

    NASA Technical Reports Server (NTRS)

    Harding, A. K.; Stecker, F. W.

    1984-01-01

    The radial distribution of gamma ray emissivity in the Galaxy was derived from flux longitude profiles, using both the final SAS-2 results and the recently corrected COS-B results and analyzing the northern and southern galactic regions separately. The recent CO surveys of the Southern Hemisphere, were used in conjunction with the Northern Hemisphere data, to derive the radial distribution of cosmic rays on both sides of the galactic plane. In addition to the 5 kpc ring, there is evidence from the radial asymmetry for spiral features which are consistent with those derived from the distribution of bright HII regions. Positive evidence was also found for a strong increase in the cosmic ray flux in the inner Galaxy, particularly in the 5 kpc region in both halves of the plane.

  17. Radial distribution of charged particles in a magnetic field

    SciTech Connect

    Sjue, S. K. L. Broussard, L. J.; Makela, M.; McGaughey, P. L.; Young, A. R.; Zeck, B. A.

    2015-02-15

    The radial spread of charged particles emitted from a point source in a magnetic field is a potential source of systematic error for any experiment where magnetic fields guide charged particles to detectors with finite size. Assuming uniform probability as a function of the phase along the particle’s helical trajectory, an analytic solution for the radial probability distribution function follows which applies to experiments in which particles are generated throughout a volume that spans a sufficient length along the axis of a homogeneous magnetic field. This approach leads to the same result as a different derivation given by Dubbers et al., Nucl. Instrum. Methods Phys. Res., Sect. A 763, 112–119 (2014). But the constant phase approximation does not strictly apply to finite source volumes or fixed positions, which lead to local maxima in the radial distribution of emitted particles at the plane of the detector. A simple method is given to calculate such distributions, then the effect is demonstrated with data from a {sup 207}Bi electron-conversion source in the superconducting solenoid magnet spectrometer of the Ultracold Neutron facility at the Los Alamos Neutron Science Center. Implications for neutron beta decay spectroscopy are discussed.

  18. Radial transport in the Earth's radiation belts (Invited)

    NASA Astrophysics Data System (ADS)

    Kress, B. T.; Ukhorskiy, A. Y.; Hudson, M. K.

    2010-12-01

    For over forty years the standard approach to modeling the dynamics of the Earth's radiation belts has been based on a diffusion equation, which can be derived from the Vlasov equation using a quasilinear approximation. The radiation belt diffusion equation describes the evolution of a particle distribution function in a space of one or several of the three adiabatic invariants associated with the motions of a charged particle in a dipole magnetic field. Increasingly, observations and theoretical studies suggest that fully nonlinear transport, not modeled by quasilinear diffusion, plays an important role in radiation belt dynamics, e.g., the shock-drift mechanism modeled by Li et al. [1993]. This presentation will focus on radiation belt particle transport across magnetic L-shells (loosely called radial transport). Radial transport is thought to be one of the primary drivers of radiation belt dynamics. A comprehensive review of the known mechanisms of radial transport and some of their effects will be given, including those that can be modeled with a diffusion equation and those requiring a fully nonlinear treatment. Li, X., I. Roth, M. Temerin, J. R. Wygant, M. K. Hudson, and J. B. Blake, (1993), Simulations of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC, Geophys. Res. Lett., 20, 2423.

  19. Using radial NMR profiles to characterize pore size distributions

    NASA Astrophysics Data System (ADS)

    Deriche, Rachid; Treilhard, John

    2012-02-01

    Extracting information about axon diameter distributions in the brain is a challenging task which provides useful information for medical purposes; for example, the ability to characterize and monitor axon diameters would be useful in diagnosing and investigating diseases like amyotrophic lateral sclerosis (ALS)1 or autism.2 Three families of operators are defined by Ozarslan,3 whose action upon an NMR attenuation signal extracts the moments of the pore size distribution of the ensemble under consideration; also a numerical method is proposed to continuously reconstruct a discretely sampled attenuation profile using the eigenfunctions of the simple harmonic oscillator Hamiltonian: the SHORE basis. The work presented here extends Ozarlan's method to other bases that can offer a better description of attenuation signal behaviour; in particular, we propose the use of the radial Spherical Polar Fourier (SPF) basis. Testing is performed to contrast the efficacy of the radial SPF basis and SHORE basis in practical attenuation signal reconstruction. The robustness of the method to additive noise is tested and analysed. We demonstrate that a low-order attenuation signal reconstruction outperforms a higher-order reconstruction in subsequent moment estimation under noisy conditions. We propose the simulated annealing algorithm for basis function scale parameter estimation. Finally, analytic expressions are derived and presented for the action of the operators on the radial SPF basis (obviating the need for numerical integration, thus avoiding a spectrum of possible sources of error).

  20. Radial distribution function of semiflexible oligomers with stretching flexibility

    NASA Astrophysics Data System (ADS)

    Zhang, Xi; Bao, Lei; Wu, Yuan-Yan; Zhu, Xiao-Long; Tan, Zhi-Jie

    2017-08-01

    The radial distribution of the end-to-end distance Ree is crucial for quantifying the global size and flexibility of a linear polymer. For semiflexible polymers, several analytical formulas have been derived for the radial distribution of Ree ignoring the stretching flexibility. However, for semiflexible oligomers, such as DNA or RNA, the stretching flexibility can be rather pronounced and can significantly affect the radial distribution of Ree. In this study, we obtained an extended formula that includes the stretch modulus to describe the distribution of Ree for semiflexible oligomers on the basis of previous formulas for semiflexible polymers without stretching flexibility. The extended formula was validated by extensive Monte Carlo simulations over wide ranges of the stretch modulus and persistence length, as well as all-atom molecular dynamics simulations of short DNAs and RNAs. Additionally, our analyses showed that the effect of stretching flexibility on the distribution of Ree becomes negligible for DNAs longer than ˜130 base pairs and RNAs longer than ˜240 base pairs.

  1. Radial distribution of charged particles in a magnetic field

    NASA Astrophysics Data System (ADS)

    Sjue, S. K. L.; Broussard, L. J.; Makela, M.; McGaughey, P. L.; Young, A. R.; Zeck, B. A.

    2015-02-01

    The radial spread of charged particles emitted from a point source in a magnetic field is a potential source of systematic error for any experiment where magnetic fields guide charged particles to detectors with finite size. Assuming uniform probability as a function of the phase along the particle's helical trajectory, an analytic solution for the radial probability distribution function follows which applies to experiments in which particles are generated throughout a volume that spans a sufficient length along the axis of a homogeneous magnetic field. This approach leads to the same result as a different derivation given by Dubbers et al., Nucl. Instrum. Methods Phys. Res., Sect. A 763, 112-119 (2014). But the constant phase approximation does not strictly apply to finite source volumes or fixed positions, which lead to local maxima in the radial distribution of emitted particles at the plane of the detector. A simple method is given to calculate such distributions, then the effect is demonstrated with data from a 207Bi electron-conversion source in the superconducting solenoid magnet spectrometer of the Ultracold Neutron facility at the Los Alamos Neutron Science Center. Implications for neutron beta decay spectroscopy are discussed.

  2. Radial Breathing Modes in Cosmochemistry and Meteoritics

    NASA Technical Reports Server (NTRS)

    Wilson, T.L.; Wilson, K.B.

    2009-01-01

    One area of continuing interest in cosmochemistry and meteoritics (C&M) is the identification of the nature of Q-phase, although some researchers in C&M are not reporting relevant portions of Raman spectral data. Q is the unidentified carrier of noble gases in carbonaceous chondrites (CCs). Being carbonaceous, the focus has been on any number of Q-candidates arising from the sp2 hybridization of carbon (C). These all derive from various forms of graphene, a monolayer of C atoms packed into a two-dimensional (2D) hexagonal honeycomb lattice that is the basic building block for graphitic materials of all other dimensions for sp2 allotropes of C. As a basic lattice, 2D graphene can be curled into fullerenes (0D), wrapped into carbon nanotubes or CNTs (1D), and stacked into graphite (3D). These take such additional forms as scroll-like carbon whiskers, carbon fibers, carbon onions, GPCs (graphite polyhedral crystals) [6], and GICs (graphite intercalation compounds). Although all of these have been observed in meteoritics, the issue is which can explain the Q-abundances. In brief, one or more of the 0D-3D sp2 hybridization forms of C is Q. For some Q-candidates, the radial breathing modes (RBMs) are the most important Raman active vibrational modes that exist, and bear a direct relevance to solving this puzzle. Typically in C&M they are ignored when present. Their importance is addressed here as smoking-gun signatures for certain Q-candidates and are very relevant to the ultimate identification of Q.

  3. Radial gate evaluation: Olympus Dam, Colorado

    SciTech Connect

    1997-06-01

    The report presents a structural analysis of the radial gates of Olympus Dam in eastern Colorado. Five 20-foot wide by 17-foot high radial gates are used to control flow through the spillway at Olympus Dam. The spillway gates were designed in 1947. The gate arm assemblies consist of two separate wide flange beams, with a single brace between the arms. The arms pivot about a 4.0-inch diameter pin and bronze graphite-insert bushing. The pin is cantilevered from the pier anchor girder. The radial gates are supported by a pin bearing on a pier anchor birder bolted to the end of the concrete pier. The gates are operated by two-part wire rope 15,000-pound capacity hoise. Stoplog slots upstream of the radial gates are provided in the concrete piers. Selected drawings of the gates and hoists are located in appendix A.

  4. Radial Velocity Fluctuations of RZ Psc

    NASA Astrophysics Data System (ADS)

    Potravnov, I. S.; Gorynya, N. A.; Grinin, V. P.; Minikulov, N. Kh.

    2014-12-01

    The behavior of the radial velocity of the UX Ori type star RZ Psc is studied. The existence of an inner cavity with a radius of about 0.7 a.u. in the circumstellar disk of this star allows to suggest the presence of a companion. A study of the radial velocity of RZ Psc based on our own measurements and published data yields no periodic component in its variability. The two most accurate measurements of V r , based on high resolution spectra obtained over a period of three months, show that the radial velocity is constant over this time interval to within 0.5 km/s. This imposes a limit of M p ≤10 M Jup on the mass of the hypothetical companion. Possible reasons for the observed strong fluctuations in the radial velocity of this star are discussed.

  5. Radial construction of an arterial wall.

    PubMed

    Greif, Daniel M; Kumar, Maya; Lighthouse, Janet K; Hum, Justine; An, Andrew; Ding, Ling; Red-Horse, Kristy; Espinoza, F Hernan; Olson, Lorin; Offermanns, Stefan; Krasnow, Mark A

    2012-09-11

    Some of the most serious diseases involve altered size and structure of the arterial wall. Elucidating how arterial walls are built could aid understanding of these diseases, but little is known about how concentric layers of muscle cells and the outer adventitial layer are assembled and patterned around endothelial tubes. Using histochemical, clonal, and genetic analysis in mice, here we show that the pulmonary artery wall is constructed radially, from the inside out, by two separate but coordinated processes. One is sequential induction of successive cell layers from surrounding mesenchyme. The other is controlled invasion of outer layers by inner layer cells through developmentally regulated cell reorientation and radial migration. We propose that a radial signal gradient controls these processes and provide evidence that PDGF-B and at least one other signal contribute. Modulation of such radial signaling pathways may underlie vessel-specific differences and pathological changes in arterial wall size and structure.

  6. Rotordynamic Forces Developed by Labyrinth Seals

    DTIC Science & Technology

    1984-11-01

    force coefficient model was also developed. Predictions obtain from the approximate model are much more sensitive to shaft speed than corresponding...configuration with fluid prerotation in the direction of shaft rotation. The independent variable is running speed and families of curves are...tooth radial clearance a-0.216 mm. and radial distance from cavity base to stator wall d-1,105 mm, The shaft speed flm33.410 rpm. the mean cavity

  7. Off-axis radial properties of undulator light

    NASA Astrophysics Data System (ADS)

    Tatchyn, Roman; Lindau, Ingolf

    The spatial and polarization properties of light from a transverse sinusoidal undulator are investigated analytically by means of numerical simulations for the single-electron case. The terminology used in the analysis is introduced; formulations for the off-axis intensity patterns, the rest-frame analysis, and radial harmonic maxima are derived; and numerical results are presented in extensive tables and graphs and briefly characterized. It is suggested that the present approach can be extended to treat higher rings and harmonics, coherent interaction among electrons (as in beam bunching and FELs), and random imperfections in undulators.

  8. Elbow dislocation with irreparable fracture radial head

    PubMed Central

    Tanna, Dilip

    2013-01-01

    Background: Treatment of elbow dislocation with irreparable radial head fracture needs replacement of radial head to achieve stability of elbow. An alternate method in cases of elbow dislocation with radial head fracture can be resection of radial head with repair of medial collateral ligament. We report a retrospective analysis of cases of elbow dislocation with irreparable radial head treated by excision head of radius and repair of MCL. Materials and Methods: Nine patients of elbow dislocation with associated irreparable fractures of the head of the radius were included in this analysis (6 F:3 M, Age: 35-47 years). Radial head excision was done through the lateral approach and MCL was sutured using no 3 Ethibond using medial approach. Above elbow plaster was given for 6 weeks and gradual mobilization was done thereafter. All patients were assessed at final followup using Mayo elbow performance score (MEPS). Results: Mean followup was 19.55 ± 7.12 months (range 14-36 months). There was no extension deficit when compared to opposite side with mean range of flexion of 138.8° ± 6.97° (range 130 -145°). Mean pronation was 87.7° ± 4.4° (range 80-90°) and mean supination was 87.7 ± 4.62° (range 80-90°). The mean MEPS was 98.8 ± 3.33 (range 90-100). No patient had pain, sensory complaints, subluxation or redislocation. All were able to carry out their daily activities without disability. Conclusion: Radial head excision with MCL repair is an acceptable option for treatment of patients with elbow dislocation and irreparable radial head fracture. PMID:23798760

  9. Radial averages of astigmatic TEM images.

    PubMed

    Fernando, K Vince

    2008-10-01

    The Contrast Transfer Function (CTF) of an image, which modulates images taken from a Transmission Electron Microscope (TEM), is usually determined from the radial average of the power spectrum of the image (Frank, J., Three-dimensional Electron Microscopy of Macromolecular Assemblies, Oxford University Press, Oxford, 2006). The CTF is primarily defined by the defocus. If the defocus estimate is accurate enough then it is possible to demodulate the image, which is popularly known as the CTF correction. However, it is known that the radial average is somewhat attenuated if the image is astigmatic (see Fernando, K.V., Fuller, S.D., 2007. Determination of astigmatism in TEM images. Journal of Structural Biology 157, 189-200) but this distortion due to astigmatism has not been fully studied or understood up to now. We have discovered the exact mathematical relationship between the radial averages of TEM images with and without astigmatism. This relationship is determined by a zeroth order Bessel function of the first kind and hence we can exactly quantify this distortion in the radial averages of signal and power spectra of astigmatic images. The argument to this Bessel function is similar to an aberration function (without the spherical aberration term) except that the defocus parameter is replaced by the differences of the defoci in the major and minor axes of astigmatism. The ill effects due this Bessel function are twofold. Since the zeroth order Bessel function is a decaying oscillatory function, it introduces additional zeros to the radial average and it also attenuates the CTF signal in the radial averages. Using our analysis, it is possible to simulate the effects of astigmatism in radial averages by imposing Bessel functions on idealized radial averages of images which are not astigmatic. We validate our theory using astigmatic TEM images.

  10. Characteristics of radial ion-plasma accelerators

    NASA Astrophysics Data System (ADS)

    Bondarenko, S. M.; Korolev, C. V.; Movsesyants, Yu B.; Tyuryukanov, P. M.

    2017-07-01

    The characteristics of two-stage ion-plasma accelerators are presented. These accelerators are based on a discharge in a transverse highly-inhomogeneous magnetic field and can form radially converging and divergent flows. It is shown that for a radially convergent flow the width of the ion acceleration zone is limited by the condition of a transition through the ion sound point in the vicinity of the plasma ion emitting boundary.

  11. Mathematical interpretation of radial shearing interferometers.

    PubMed

    Malacara, D

    1974-08-01

    The procedure for computing a radial shearing interferometric pattern is given. The interferometric pattern is analyzed to obtain the wavefront shape. Restricting the discussion to wavefronts having rotational symmetry, we give two different methods of finding the wavefront. One approach is to scan along a diameter of the interferometric pattern and the other is to examine the shape of the fringes. The relative sensitivity of a radial shearing interferometer with respect to that of a Twyman-Green interferometer is also analyzed.

  12. Radial transport with perturbed magnetic field

    SciTech Connect

    Hazeltine, R. D.

    2015-05-15

    It is pointed out that the viscosity coefficient describing radial transport of toroidal angular momentum is proportional to the second power of the gyro-radius—like the corresponding coefficients for particle and heat transport—regardless of any geometrical symmetry. The observation is widely appreciated, but worth emphasizing because some literature gives the misleading impression that asymmetry can allow radial moment transport in first-order.

  13. Non-linear radial oscillations of a transversely isotropic hyperelastic incompressible tube

    NASA Astrophysics Data System (ADS)

    Mason, D. P.; Maluleke, G. H.

    2007-09-01

    The constitutive equation for a transversely isotropic incompressible hyperelastic material is written in a covariant form for arbitrary orientation of the anisotropic director. Three non-linear differential equations are derived for radial oscillations in radial, tangential and longitudinal transversely isotropic thin-walled cylindrical tubes of generalised Mooney-Rivlin material. A Lie point symmetry analysis is performed. The conditions on the strain-energy function and on the net applied surface pressure for Lie point symmetries to exist are determined. For radial and tangential transversely isotropic tubes the differential equations are reduced to Abel equations of the second kind. Radial oscillations in a longitudinal transversely isotropic tube and in an isotropic tube are described by the Ermakov-Pinney equation.

  14. Radial vibration of free anisotropic nanoparticles based on nonlocal continuum mechanics.

    PubMed

    Ghavanloo, Esmaeal; Fazelzadeh, S Ahmad

    2013-02-22

    Radial vibration of spherical nanoparticles made of materials with anisotropic elasticity is theoretically investigated using nonlocal continuum mechanics. The anisotropic elastic model is reformulated using the nonlocal differential constitutive relations of Eringen. The nonlocal differential equation of radial motion is derived in terms of radial displacement. Cubic, hexagonal, trigonal and tetragonal symmetries of the elasticity are discussed. The suggested model is justified by a good agreement between the results given by the present model and available experimental data. Furthermore, the model is used to elucidate the effect of small scale on the vibration of several nanoparticles. Our results show that the small scale is essential for the radial vibration of the nanoparticles when the nanoparticle radius is smaller than 1.5 nm.

  15. An extensive radial velocity survey towards NGC 6253

    NASA Astrophysics Data System (ADS)

    Montalto, M.; Melo, C. H. F.; Santos, N. C.; Queloz, D.; Piotto, G.; Desidera, S.; Bedin, L. R.; Momany, Y.; Saviane, I.

    2016-04-01

    The old and metal-rich open cluster NGC 6253 was observed with the Fibre Large Array Multi Element Spectrograph (FLAMES) multi-object spectrograph during an extensive radial velocity campaign monitoring 317 stars with a median of 15 epochs per object. All the targeted stars are located along the upper main sequence of the cluster between 14.8 < V < 16.5. Fifty nine stars are confirmed cluster members both by radial velocities and proper motions and do not show evidence of variability. We detected 45 variable stars among which 25 belong to NGC 6253. We were able to derive an orbital solution for four cluster members (and for two field stars) yielding minimum masses in between ˜90 MJ and ˜460 MJ and periods between 3 and 220 d. Simulations demonstrated that this survey was sensitive to objects down to 30 MJ at 10 days orbital periods with a detection efficiency equal to 50 per cent. On the basis of these results we concluded that the observed frequency of binaries down to the hydrogen burning limit and up to 20 d orbital period is around (1.5 ± 1.3) per cent in NGC 6253. The overall observed frequency of binaries around the sample of cluster stars is (13 ± 3) per cent. The median radial velocity precision achieved by the GIRAFFE spectrograph in this magnitude range was around ˜240 m s- 1 (˜180 m s- 1 for UVES). Based on a limited follow-up analysis of seven stars in our sample with the High Accuracy Radial velocity Planet Searcher (HARPS) spectrograph we determined that a precision of 35 m s- 1 can be reached in this magnitude range, offering the possibility to further extend the variability analysis into the substellar domain. Prospects are even more favourable once considering the upcoming ESPRESSO spectrograph at VLT.

  16. Response of radiation belt simulations to different radial diffusion coefficients

    NASA Astrophysics Data System (ADS)

    Drozdov, A.; Shprits, Y.; Subbotin, D.; Kellerman, A. C.

    2013-12-01

    Resonant interactions between Ultra Low Frequency (ULF) waves and relativistic electrons may violate the third adiabatic invariant of motion, which produces radial diffusion in the electron radiation belts. This process plays an important role in the formation and structure of the outer electron radiation belt and is important for electron acceleration and losses in that region. Two parameterizations of the resonant wave-particle interaction of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate their relative effect on the radiation belt simulation. The period of investigation includes quiet time and storm time geomagnetic activity and is compared to data based on satellite observations. Our calculations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. We show that the results of the 3D diffusion simulations depend on the assumed parametrization of waves. The differences between the simulations and potential missing physical mechanisms are discussed. References Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

  17. Analytical design of an advanced radial turbine

    SciTech Connect

    Large, G.D.; Finger, D.G.; Linder, C.G.

    1981-02-01

    The analytical design of an advanced radial turbine, which is part of an optimum ceramic radial inflow, single-stage turbine system for an advanced automotive gas turbine engine is reported. The turbine study program is based on an advanced gas turbine cycle, 100.67-kW (135-shp) engine for use in a 1588-kg (3500-lb) automobile, with a specific fuel consumption of 0.227 kg/kW-hr (0.373 lb/hp-hr). Utilization of high turbine cycle temperatures of 1370/sup 0/C and ceramic materials are prime features of this study. The program objective was to investigate the effects of tip speed, non-radial rotor blading, inducer-to-exducer work split, and deswirl vanes on the system efficiency and mechanical reliability of a single-stage, ceramic, radial turbine designed to meet the performance requirements of an advanced automotive gas turbine cycle. Analysis results indicate that, based on projected 1983 aerodynamic performance and ceramic material properties, radial blade rotor configurations with a tip speed of 701 m/sec (2300 fps) are feasible and satisfy the goals of 87.0% system efficiency and 0.9999 cumulative probability of success mechanically. As compared with the blade stress complications of nonradial rotor configurations, from aerodynamic, mechanical, and off-design considerations, the radial-blade rotor appears to offer the lowest overall risk and is the optimum configuration considered in this study.

  18. Radial pulsations in DB white dwarfs?

    NASA Technical Reports Server (NTRS)

    Kawaler, Steven D.

    1993-01-01

    Theoretical models of DB white dwarfs are unstable against radial pulsation at effective temperatures near 20,000-30,000 K. Many high-overtone modes are unstable, with periods ranging from 12 s down to the acoustic cutoff period of approximately 0.1 s. The blue edge for radial instability lies at slightly higher effective temperatures than for nonradial pulsations, with the temperature of the blue edge dependent on the assumed efficiency of convection. Models with increased convective efficiency have radial blue edges that are increasingly closer to the nonradial blue edge; in all models the instability persists into the nonradial instability strip. Radial pulsations therefore may exist in the hottest DB stars that lie below the DB gap; the greatest chance for detection would be observations in the ultraviolet. These models also explain why searches for radial pulsations in DA white dwarfs have failed: the efficient convection needed to explain the blue edge for nonradial DA pulsation means that the radial instability strip is 1000 K cooler than found in previous investigations. The multiperiodic nature of the expected pulsations can be used to advantage to identify very low amplitude modes using the uniform spacing of the modes in frequency. This frequency spacing is a direct indicator of the mass of the star.

  19. Assessment of the effect of intraarticular injection of autologous adipose-derived mesenchymal stem cells in osteoarthritic dogs using a double blinded force platform analysis

    PubMed Central

    2014-01-01

    Background Regenerative medicine using Mesenchymal Stem Cells (MSC) alone or combined with Plasma Rich in Growth Factors (PRGF) is a rapidly growing area of clinical research and is currently also being used to treat osteoarthritis (OA). Force platform analysis has been consistently used to verify and quantify the efficacy of different therapeutic strategies for the treatment of OA in dogs including MSC associated to PRGF, but never with AD-MSC alone. The aim of this study was to use a force platform to measure the efficacy of intraarticular ADMSC administration for limb function improvement in dogs with severe OA. Results Ten lame dogs with severe hip OA and a control group of 5 sound dogs were used for this study. Results were statistically analyzed to detect a significant increase in peak vertical force (PVF) and vertical impulse (VI) in treated dogs. Mean values of PVF and VI were significantly improved within the first three months post-treatment in the OA group, increasing 9% and 2.5% body weight, respectively, at day 30. After this, the effect seems to decrease reaching initial values. Conclusion Intraarticular ADMSC therapy objectively improved limb function in dogs with hip OA. The duration of maximal effect was less than 3 months. PMID:24984756

  20. Radial glia and somal translocation of radial neurons in the developing cerebral cortex.

    PubMed

    Nadarajah, Bagirathy

    2003-07-01

    A series of recent studies have demonstrated that radial glia are neural precursors in the developing cerebral cortex. These studies have further implied that these cells are the sole precursor constituents of the dorsal forebrain ventricular zone that generate the projection neurons of the cortex. In view of these new findings, this review discusses radial neurons, a progeny of cortical neurons that are generated by radial glia and adopt somal translocation as the mode of migration.

  1. Megadroughts in Millennium-Length Forced and Control Simulations and their Comparison to the Proxy-derived North American Drought Atlas

    NASA Astrophysics Data System (ADS)

    Coats, S.; Smerdon, J. E.; Seager, R.; Cook, B. I.; Gonzalez-Rouco, F. J.

    2012-12-01

    Some of the starkest features of proxy-estimated hydroclimate variability in the North American Southwest (NASW; 125°W-105°W, 25°N-42.5°N) are the severe and multidecadal drought periods that have existed in the region. These so called megadroughts are a prominent and well-established feature of the NASW's hydroclimate history. Given the prominence of these features in our recent past, it is imperative to consider whether Atmosphere-Ocean General Circulation Models (AOGCMs) are capable of simulating these events and if such features of past hydroclimate change are forced or the product of internal variability. Simulated hydroclimate variability in millennium-length forced transient and control runs from the ECHO-G coupled AOGCM is analyzed and compared to reconstructed Palmer Drought Severity Index (PDSI) variability from the North American Drought Atlas (NADA). Megadroughts in the ECHO-G AOGCM are found to be similar in duration and magnitude to those estimated from the NADA. The droughts in the forced simulation are not, however, temporally synchronous with those in the paleoclimate record, nor are there significant differences between the megadrought features simulated in the forced and control runs. These results indicate that model-simulated megadroughts can result from internal variability of the modeled climate system, rather than as a response to changes in exogenous forcings. Although the ECHO-G AOGCM is capable of simulating megadroughts by means of persistent La-Nina-like conditions in the tropical Pacific, other mechanisms can produce similarly extreme NASW moisture anomalies in the model. In particular, the lack of low-frequency coherence between NASW soil moisture and other modeled fields and the Pacific Decadal Oscillation and Atlantic Multidecadal Oscillation indices during identified drought periods, suggests that stochastic atmospheric variability can contribute significantly to the occurrence of simulated megadroughts in the NASW by means of

  2. Study of radial die-wall pressure changes during pharmaceutical powder compaction.

    PubMed

    Abdel-Hamid, Sameh; Betz, Gabriele

    2011-04-01

    In tablet manufacturing, less attention is paid to the measurement of die-wall pressure than to force-displacement diagrams. Therefore, the aim of this study was to investigate radial stress change during pharmaceutical compaction. The Presster(TM), a tablet-press replicator, was used to characterize compaction behavior of microcrystalline cellulose (viscoelastic), calcium hydrogen phosphate dihydrate (brittle), direct compressible mannitol (plastic), pre-gelatinized starch (plastic/elastic), and spray dried lactose monohydrate (plastic/brittle) by measuring radial die-wall pressure; therefore powders were compacted at different (pre) compaction pressures as well as different speeds. Residual die-wall pressure (RDP) and maximum die-wall pressure (MDP) were measured. Various tablet physical properties were correlated to radial die-wall pressure. With increasing compaction pressure, RDP and MDP (P < 0.0001) increased for all materials, with increasing precompaction RDP decreased for plastic materials (P < 0.05), whereas with increasing speed MDP decreased for all materials (P < 0.05). During decompression, microcrystalline cellulose and pre-gelatinized starch showed higher axial relaxation, whereas mannitol and lactose showed higher radial relaxation, calcium hydrogen phosphate showed high axial and radial relaxations. Plastic and brittle materials showed increased tendencies for friction because of high radial relaxation. Die-wall monitoring is suggested as a valuable tool for characterizing compaction behavior of materials and detecting friction phenomena in the early stage of development.

  3. [Elbow dislocation with ipsilateral proximal radial shaft fracture and radial head dislocation].

    PubMed

    Köhn, N; Mendel, T; Ullrich, B W

    2015-11-01

    Elbow dislocation with ipsilateral proximal radial shaft fracture and dislocated radial head is a rarely described injury. In this article we present the case of a 23-year-old man with this injury. After the initial diagnostics, the radial shaft fracture was osteosynthetically fixed, whereby the anatomical positions of all parts of the elbow joint were correctly aligned and the medial collateral ligament was reconstructed. After 4.5 months the radial shaft fracture was healed with nearly complete functional recovery of the upper extremity. Thus, a good outcome can be expected when all aspects of bony and ligamentous injuries are accurately addressed.

  4. Radial artery access for peripheral endovascular procedures.

    PubMed

    Kumar, Avnee J; Jones, Lauren E; Kollmeyer, Kenneth R; Feldtman, Robert W; Ferrara, Craig A; Moe, Michelle N; Chen, Julia F; Richmond, Jasmine L; Ahn, Sam S

    2017-09-01

    The radial artery is often used for coronary angiography, with a demonstrated decrease in local complications and an increase in postoperative mobility of the patient. Data on radial artery access for peripheral endovascular procedures, however, are limited. We describe our experience with radial artery access for diagnostic and endovascular interventions. Between February 2012 and March 2015, there were 95 endovascular procedures performed using radial artery access in 80 unique patients. Demographic and clinical data were recorded. Perioperative, postoperative, and 30-day follow-up data were evaluated retrospectively for major and minor complications. Major adverse events included any immediate hospitalization admission, stroke, hand amputation, bleeding requiring transfusion, hematoma requiring surgery, and death. Minor complications included superficial bleeding and hematoma. The patients (52.6% male, 47.4% female) had a mean age of 72.1 ± 9.4 years. Radial artery access was used for diagnostic purposes in 15.8% of all procedures and for therapeutic intervention, including angioplasty and stenting, in 84.2%. The radial artery was the only access point in 80% of patients and was accessed in conjunction with other sites in 20%. Percutaneous access was achieved in 100% of patients with a 100% technical success rate. Hemostasis after catheterization was achieved by manual compression (22.1%) and TR band (Terumo Medical, Tokyo, Japan; 77.9%). Major adverse events occurred in three cases (3.2%) and were unrelated to radial artery access. Radial artery access site-related complications occurred in three cases (3.2%), all of which were minor hematomas that required no treatment. The risk of radial artery complication was not associated with procedure type, vessels treated, or use of heparin. The incidence of stroke, hand ischemia, and upper extremity limb or finger loss was 0%. Radial artery access for peripheral endovascular procedures appears to be safe and

  5. The effect of radial head implant shape on radiocapitellar kinematics during in vitro forearm rotation.

    PubMed

    Shannon, Hannah L; Deluce, Simon R; Giles, Joshua W; Johnson, James A; King, Graham J W

    2015-02-01

    A number of radial head implants are in clinical use for the management of radial head fractures and their sequelae. However, the optimal shape of a radial head implant to ensure proper tracking relative to the capitellum has not been established. This in vitro biomechanical study compared radiocapitellar joint kinematics for 3 radial head implant designs as well as the native head. Eight cadaveric upper extremities were tested using a forearm rotation simulator with the elbow at 90° of flexion. Motion of the radius relative to the capitellum was optically tracked. A stem was navigated into a predetermined location and cemented in place. Three unipolar implant shapes were tested: axisymmetric, reverse-engineered patient-specific, and population-based quasi-anatomic. The patient-specific and quasi-anatomic implants were derived from measurements performed on computed tomography models. Medial-lateral and anterior-posterior translation of the radial head with respect to the capitellum varied with forearm rotation and radial head condition. A significant difference in medial-lateral (P = .03) and anterior-posterior (P = .03) translation was found between the native radial head and the 3 implants. No differences were observed among the radial head conditions except for a difference in medial-lateral translation between the axisymmetric and patient-specific implants (P = .04). Radiocapitellar kinematics of the tested radial head implants were similar in all but one comparison, and all had different kinematics from the native radial head. Patient-specific radial head implants did not prove advantageous relative to conventional implant designs. The shape of the fixed stem unipolar radial head implants had little influence on radiocapitellar kinematics when optimally positioned in this testing model. Copyright © 2015 Journal of Shoulder and Elbow Surgery Board of Trustees. Published by Elsevier Inc. All rights reserved.

  6. Impact of mountain pine beetle outbreaks on forest albedo and radiative forcing, as derived from Moderate Resolution Imaging Spectroradiometer, Rocky Mountains, USA

    NASA Astrophysics Data System (ADS)

    Vanderhoof, M.; Williams, C. A.; Ghimire, B.; Rogan, J.

    2013-12-01

    pine beetle (Dendroctonus ponderosae) outbreaks in North America are widespread and have potentially large-scale impacts on albedo and associated radiative forcing. Mountain pine beetle outbreaks in Colorado and southern Wyoming have resulted in persistent and significant increases in both winter albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.05 ± 0.01, in lodgepole pine (Pinus contorta) and ponderosa pine (Pinus ponderosa) stands, respectively) and spring albedo (change peaked 10 years post outbreak at 0.06 ± 0.01 and 0.04 ± 0.01, in lodgepole pine and ponderosa pine stands, respectively). Instantaneous top-of-atmosphere radiative forcing peaked for both lodgepole pine and ponderosa pine stands in winter at 10 years post outbreak at -1.7 ± 0.2 W m-2 and -1.4 ± 0.2 W m-2, respectively. The persistent increase in albedo with time since mountain pine beetle disturbance combined with the continued progression of the attack across the landscape from 1994-2011 resulted in an exponential increase in winter and annual radiative cooling (MW) over time. In 2011 the rate of radiative forcing within the study area reached -982.7 ± 139.0 MW, -269.8 ± 38.2 MW, -31.1 ± 4.4 MW, and -147.8 ± 20.9 MW in winter, spring, summer, and fall, respectively. An increase in radiative cooling has the potential to decrease sensible and/or latent heat flux by reducing available energy. Such changes could affect current mountain pine beetle outbreaks which are influenced by climatic conditions.

  7. The effects of voluntary, involuntary, and forced exercises on brain-derived neurotrophic factor and motor function recovery: a rat brain ischemia model.

    PubMed

    Ke, Zheng; Yip, Shea Ping; Li, Le; Zheng, Xiao-Xiang; Tong, Kai-Yu

    2011-02-08

    Stroke rehabilitation with different exercise paradigms has been investigated, but which one is more effective in facilitating motor recovery and up-regulating brain neurotrophic factor (BDNF) after brain ischemia would be interesting to clinicians and patients. Voluntary exercise, forced exercise, and involuntary muscle movement caused by functional electrical stimulation (FES) have been individually demonstrated effective as stroke rehabilitation intervention. The aim of this study was to investigate the effects of these three common interventions on brain BDNF changes and motor recovery levels using a rat ischemic stroke model. One hundred and seventeen Sprague-Dawley rats were randomly distributed into four groups: Control (Con), Voluntary exercise of wheel running (V-Ex), Forced exercise of treadmill running (F-Ex), and Involuntary exercise of FES (I-Ex) with implanted electrodes placed in two hind limb muscles on the affected side to mimic gait-like walking pattern during stimulation. Ischemic stroke was induced in all rats with the middle cerebral artery occlusion/reperfusion model and fifty-seven rats had motor deficits after stroke. Twenty-four hours after reperfusion, rats were arranged to their intervention programs. De Ryck's behavioral test was conducted daily during the 7-day intervention as an evaluation tool of motor recovery. Serum corticosterone concentration and BDNF levels in the hippocampus, striatum, and cortex were measured after the rats were sacrificed. V-Ex had significantly better motor recovery in the behavioral test. V-Ex also had significantly higher hippocampal BDNF concentration than F-Ex and Con. F-Ex had significantly higher serum corticosterone level than other groups. Voluntary exercise is the most effective intervention in upregulating the hippocampal BDNF level, and facilitating motor recovery. Rats that exercised voluntarily also showed less corticosterone stress response than other groups. The results also suggested that the

  8. Direct observation of CD4 T cell morphologies and their cross-sectional traction force derivation on quartz nanopillar substrates using focused ion beam technique

    NASA Astrophysics Data System (ADS)

    Kim, Dong-Joo; Kim, Gil-Sung; Hyung, Jung-Hwan; Lee, Won-Yong; Hong, Chang-Hee; Lee, Sang-Kwon

    2013-07-01

    Direct observations of the primary mouse CD4 T cell morphologies, e.g., cell adhesion and cell spreading by culturing CD4 T cells in a short period of incubation (e.g., 20 min) on streptavidin-functionalized quartz nanopillar arrays (QNPA) using a high-content scanning electron microscopy method were reported. Furthermore, we first demonstrated cross-sectional cell traction force distribution of surface-bound CD4 T cells on QNPA substrates by culturing the cells on top of the QNPA and further analysis in deflection of underlying QNPA via focused ion beam-assisted technique.

  9. Direct observation of CD4 T cell morphologies and their cross-sectional traction force derivation on quartz nanopillar substrates using focused ion beam technique.

    PubMed

    Kim, Dong-Joo; Kim, Gil-Sung; Hyung, Jung-Hwan; Lee, Won-Yong; Hong, Chang-Hee; Lee, Sang-Kwon

    2013-07-23

    Direct observations of the primary mouse CD4 T cell morphologies, e.g., cell adhesion and cell spreading by culturing CD4 T cells in a short period of incubation (e.g., 20 min) on streptavidin-functionalized quartz nanopillar arrays (QNPA) using a high-content scanning electron microscopy method were reported. Furthermore, we first demonstrated cross-sectional cell traction force distribution of surface-bound CD4 T cells on QNPA substrates by culturing the cells on top of the QNPA and further analysis in deflection of underlying QNPA via focused ion beam-assisted technique.

  10. Radial dependence of the dark matter distribution in M33

    NASA Astrophysics Data System (ADS)

    López Fune, E.; Salucci, P.; Corbelli, E.

    2017-06-01

    The stellar and gaseous mass distributions, as well as the extended rotation curve, in the nearby galaxy M33 are used to derive the radial distribution of dark matter density in the halo and to test cosmological models of galaxy formation and evolution. Two methods are examined to constrain the dark mass density profiles. The first method deals directly with fitting the rotation curve data in the range of galactocentric distances 0.24 ≤ r ≤ 22.72 kpc. Using the results of collisionless Λ cold dark matter numerical simulations, we confirm that the Navarro-Frenkel-White (NFW) dark matter profile provides a better fit to the rotation curve data than the cored Burkert profile (BRK) profile. The second method relies on the local equation of centrifugal equilibrium and on the rotation curve slope. In the aforementioned range of distances, we fit the observed velocity profile, using a function that has a rational dependence on the radius, and we derive the slope of the rotation curve. Then, we infer the effective matter densities. In the radial range 9.53 ≤ r ≤ 22.72 kpc, the uncertainties induced by the luminous matter (stars and gas) become negligible, because the dark matter density dominates, and we can determine locally the radial distribution of dark matter. With this second method, we tested the NFW and BRK dark matter profiles and we can confirm that both profiles are compatible with the data, even though in this case the cored BRK density profile provides a more reasonable value for the baryonic-to-dark matter ratio.

  11. On the importance of shear dissipative forces in coarse-grained dynamics of molecular liquids.

    PubMed

    Izvekov, Sergei; Rice, Betsy M

    2015-04-28

    In this work we demonstrate from first principles that the shear frictions describing dissipative forces in the direction normal to the vector connecting the coarse-grained (CG) particles in dissipative particle dynamics (DPD) could be dominant for certain real molecular liquids at high-resolution coarse-graining. This is in contrast to previous works on bottom-up DPD modeling and indicates that such liquids cannot be simulated accurately using the conventional form of DPD which relies only on frictions in the radial direction. Specifically, we describe the development of fully bottom-up CG models for liquid hexahydro-1,3,5-trinitro-s-triazine (RDX) which are incorporated into the DPD method. Consistent with the microscopic foundation of DPD dynamics, the conservative part of the DPD models is obtained by the multi-scale coarse-graining (MS-CG) approach, which implements the pairwise decomposition of the atomistic potential of mean force (PMF) in CG coordinates. The radial and shear distant-dependent friction coefficients in a parameter-free form are derived systematically from microscopic velocity and force correlation data along system trajectories using a recently proposed approach [J. Chem. Phys., 2014, 140, 104104]. The shear dissipative forces for the reported system appear to be dominant. We discuss the implications of dominant shear dissipation on dynamical and transport properties of CG liquids such as diffusion and viscosity as revealed by simulations of liquid RDX using the new MS-CG/DPD models.

  12. FDTD simulation of trapping nanowires with linearly polarized and radially polarized optical tweezers.

    PubMed

    Li, Jing; Wu, Xiaoping

    2011-10-10

    In this paper a model of the trapping force on nanowires is built by three dimensional finite-difference time-domain (FDTD) and Maxwell stress tensor methods, and the tightly focused laser beam is expressed by spherical vector wave functions (VSWFs). The trapping capacities on nanoscale-diameter nanowires are discussed in terms of a strongly focused linearly polarized beam and radially polarized beam. Simulation results demonstrate that the radially polarized beam has higher trapping efficiency on nanowires with higher refractive indices than linearly polarized beam.

  13. Effect of spiral outlet hydraulic passage geometrics on the radial thrust

    NASA Astrophysics Data System (ADS)

    Lugova, S. O.; Ignateva, P. I.

    2017-08-01

    The article presents the results of investigation of the effect of geometrics of a double-volute outlet hydraulic passage on the magnitude and direction of acting of the radial reaction forces in a between-bearings single-stage centrifugal pump with a double entry impeller. The investigation has been performed with the use of a computing experiment. Characteristic curves as well as values and directions of the radial thrust have been compared for three variants of outlet hydraulic passages differing in the width at their entrance.

  14. Comparison of Absolute Thresholds Derived from an Adaptive Forced-Choice Procedure and from Reaction Probabilities and Reaction Times in a Simple Reaction Time Paradigm

    PubMed Central

    Neubauer, Heinrich; Tiefenau, Andreas; von Specht, Hellmut

    2006-01-01

    An understanding of the auditory system's operation requires knowledge of the mechanisms underlying thresholds. In this work we compare detection thresholds obtained with a three-interval-three-alternative forced-choice paradigm with reaction thresholds extracted from both reaction probabilities (RP) and reaction times (RT) in a simple RT paradigm from the same listeners under otherwise nearly identical experimental conditions. Detection thresholds, RP, and RT to auditory stimuli exhibited substantial variation from session to session. Most of the intersession variation in RP and RT could be accounted for by intersession variation in a listener's absolute sensitivity. The reaction thresholds extracted from RP were very similar, if not identical, to those extracted from RT. On the other hand, reaction thresholds were always higher than detection thresholds. The difference between the two thresholds can be considered as the additional amount of evidence required by each listener to react to a stimulus in an unforced design on top of that necessary for detection in the forced-choice design. This difference is inversely related to the listener's probability of producing false alarms. We found that RT, once corrected for some irreducible minimum RT, reflects the time at which a given stimulus reaches the listener's reaction threshold. This suggests that the relationships between simple RT and loudness (reported in the literature) are probably caused by a tight relationship between temporal summation at threshold and temporal summation of loudness. PMID:16823660

  15. Unstable force analysis for induction motor eccentricity

    NASA Astrophysics Data System (ADS)

    Han, Xu; Palazzolo, Alan

    2016-05-01

    The increasing popularity of motors in machinery trains has led to an intensified interest in the forces they produce that may influence machinery vibration. Motor design typically assumes a uniform air gap, however in practice all motors operate with the rotor slightly displaced from the motor centerline in what is referred to as an eccentric position. Rotor center eccentricity can cause a radially unbalanced magnetic field when the motor is operating. This will results in both a radial force pulling the motor further away from the center, and a tangential force which can induce a vibration stability problem. In this paper, a magnetic equivalent circuit MEC modeling method is proposed to calculate both the radial and tangential motor eccentric force. The treatment of tangential force determination is rarely addressed, but it is very important for rotordynamic vibration stability evaluation. The proposed model is also coupled with the motor electric circuit model to provide capability for transient vibration simulations. FEM is used to verify the MEC model. A parametric study is performed on the motor radial and tangential eccentric forces. Also a Jeffcott rotor model is used to study the influence of the motor eccentric force on mechanical vibration stability and nonlinear behavior. Furthermore, a stability criteria for the bearing damping is provided. The motor radial and tangential eccentric forces are both curved fitted to include their nonlinearity in time domain transient simulation for both a Jeffcott rotor model and a geared machinery train with coupled torsional-lateral motion. Nonlinear motions are observed, including limit cycles and bifurcation induced vibration amplitude jumps.

  16. Implementation of sensorless control of radial magnetic bearings

    SciTech Connect

    Gurumoorthy, R.; Soong, W.L.; Lyons, J.P.; Storace, A.F.

    1995-12-31

    This paper discusses preliminary results of the implementation of sensorless position control of a radial magnetic bearing. The magnetic bearing is controlled using a mutually exclusive excitation scheme; where only one out of the two available actuators in each axis is active at any time. The unused actuator is used for sensorless position estimation. The sensorless position scheme is based on measuring the change of airgap reluctance with the variation of airgap between the actuator and the rotor. The airgap reluctance is measured by driving the unused actuators with short probing pulses and measuring the resultant change of current. The rotor position is controlled using independent Proportional Integral Derivative (PID) control of each axis. This offers a simple and robust controller. The authors present the design of a PID controller. Preliminary experimental results are presented showing levitation at standstill. The sensorless control algorithm has been implemented on a digital controller and levitation of the test-rig rotor with one radial bearing operated without a position sensor has been demonstrated. Due to the inherent double integration from the rotor inertia, the derivative component of the position is required for stabilizing the system. However this also inherently amplifies measurement noise and thus low-noise position estimation is required. Means for reducing the existing noise in the position estimate, in the test-rig system, by increasing the current sensor resolution and using greater filtering are being investigated.

  17. Radial Tunnel Syndrome, Diagnostic and Treatment Dilemma

    PubMed Central

    Moradi, Ali; Ebrahimzadeh, Mohammad H; Jupiter, Jess B

    2015-01-01

    Radial tunnel syndrome is a disease which we should consider it in elbow and forearm pains. It is diagnosed with lateral elbow and dorsal forearm pain may radiate to the wrist and dorsum of the fingers. The disease is more prevalent in women with the age of 30 to 50 years old. It occurs by intermittent compression on the radial nerve from the radial head to the inferior border of the supinator muscle, without obvious extensor muscle weakness. Compression could happen in five different sites but the arcade of Frose is the most common area that radial nerve is compressed. To diagnosis radial tunnel syndrome, clinical examination is more important than paraclinic tests such as electrodiagnsic test and imaging studies. The exact site of the pain which can more specified by rule of nine test and weakness of the third finger and wrist extension are valuable physical exams to diagnosis. MRI studies my show muscle edema or atrophy along the distribution of the posterior interosseous nerve. Although non-surgical treatments such as rest, NSAIDs, injections and physiotherapy do not believe to have permanent relief, but it is justify undergoing them before surgery. Surgery could diminish pain and symptoms in 67 to 93 percents of patients completely. PMID:26213698

  18. Fast radial flows in transition disk holes

    SciTech Connect

    Rosenfeld, Katherine A.; Andrews, Sean M.; Chiang, Eugene

    2014-02-20

    Protoplanetary 'transition' disks have large, mass-depleted central cavities, yet also deliver gas onto their host stars at rates comparable to disks without holes. The paradox of simultaneous transparency and accretion can be explained if gas flows inward at much higher radial speeds inside the cavity than outside the cavity, since surface density (and by extension optical depth) varies inversely with inflow velocity at fixed accretion rate. Radial speeds within the cavity might even have to approach free-fall values to explain the huge surface density contrasts inferred for transition disks. We identify observational diagnostics of fast radial inflow in channel maps made in optically thick spectral lines. Signatures include (1) twisted isophotes in maps made at low systemic velocities and (2) rotation of structures observed between maps made in high-velocity line wings. As a test case, we apply our new diagnostic tools to archival Atacama Large Millimeter Array data on the transition disk HD 142527 and uncover evidence for free-fall radial velocities inside its cavity. Although the observed kinematics are also consistent with a disk warp, the radial inflow scenario is preferred because it predicts low surface densities that appear consistent with recent observations of optically thin CO isotopologues in this disk. How material in the disk cavity sheds its angular momentum wholesale to fall freely onto the star is an unsolved problem; gravitational torques exerted by giant planets or brown dwarfs are briefly discussed as a candidate mechanism.

  19. Radial spoke proteins of Chlamydomonas flagella

    PubMed Central

    Yang, Pinfen; Diener, Dennis R.; Yang, Chun; Kohno, Takahiro; Pazour, Gregory J.; Dienes, Jennifer M.; Agrin, Nathan S.; King, Stephen M.; Sale, Winfield S.; Kamiya, Ritsu; Rosenbaum, Joel L.; Witman, George B.

    2007-01-01

    Summary The radial spoke is a ubiquitous component of ‘9+2’ cilia and flagella, and plays an essential role in the control of dynein arm activity by relaying signals from the central pair of microtubules to the arms. The Chlamydomonas reinhardtii radial spoke contains at least 23 proteins, only 8 of which have been characterized at the molecular level. Here, we use mass spectrometry to identify 10 additional radial spoke proteins. Many of the newly identified proteins in the spoke stalk are predicted to contain domains associated with signal transduction, including Ca2+-, AKAP- and nucleotide-binding domains. This suggests that the spoke stalk is both a scaffold for signaling molecules and itself a transducer of signals. Moreover, in addition to the recently described HSP40 family member, a second spoke stalk protein is predicted to be a molecular chaperone, implying that there is a sophisticated mechanism for the assembly of this large complex. Among the 18 spoke proteins identified to date, at least 12 have apparent homologs in humans, indicating that the radial spoke has been conserved throughout evolution. The human genes encoding these proteins are candidates for causing primary ciliary dyskinesia, a severe inherited disease involving missing or defective axonemal structures, including the radial spokes. PMID:16507594

  20. Experimental investigations of radial loads induced by partial cavitation with the LH2 Vulcain inducer

    NASA Astrophysics Data System (ADS)

    Goirand, B.; Mertz, A. L.; Joussellin, F.; Rebattet, C.

    Radial forces generated by partial cavitation were investigated both in water and liquid hydrogen (LH2) with the four bladed inducer of the Vulcain liquid hydrogen turbopump. A specific shaft mounted six component balance was developed for inducer water tests, in which force measurements were completed by unsteady pressure measurements and high speed flow visualizations. From water results, a good qualitative agreement with previous experiences was obtained but the influence of blade number was demonstrated. Characteristic frequencies of unsteady cavitation phenomena were identified at different operating points. The force measurements in hydrogen gave promising results about thermodynamics delay, in the scope of establishing transposition rules.

  1. Radial basis function networks and complexity regularization in function learning.

    PubMed

    Krzyzak, A; Linder, T

    1998-01-01

    In this paper we apply the method of complexity regularization to derive estimation bounds for nonlinear function estimation using a single hidden layer radial basis function network. Our approach differs from previous complexity regularization neural-network function learning schemes in that we operate with random covering numbers and l(1) metric entropy, making it possible to consider much broader families of activation functions, namely functions of bounded variation. Some constraints previously imposed on the network parameters are also eliminated this way. The network is trained by means of complexity regularization involving empirical risk minimization. Bounds on the expected risk in terms of the sample size are obtained for a large class of loss functions. Rates of convergence to the optimal loss are also derived.

  2. The usefulness of proximal radial motor conduction in acute compressive radial neuropathy.

    PubMed

    Kim, Kun Hyun; Park, Kee Duk; Chung, Pil Wook; Moon, Heui Soo; Kim, Yong Bum; Yoon, Won Tae; Park, Hyung Jun; Suh, Bum Chun

    2015-04-01

    The objective of this study was to determine diagnostic and prognostic values of proximal radial motor conduction in acute compressive radial neuropathy. Thirty-nine consecutive cases of acute compressive radial neuropathy with radial conduction studies-including stimulation at Erb's point-performed within 14 days from clinical onset were reviewed. The radial conduction data of 39 control subjects were used as reference data. Thirty-one men and eight women (age, 45.2±12.7 years, mean±SD) were enrolled. All 33 patients in whom clinical follow-up data were available experienced complete recovery, with a recovery time of 46.8±34.3 days. Partial conduction block was found frequently (17 patients) on radial conduction studies. The decrease in the compound muscle action potential area between the arm and Erb's point was an independent predictor for recovery time. Proximal radial motor conduction appears to be a useful method for the early detection and prediction of prognosis of acute compressive radial neuropathy.

  3. Radial head fracture associated with posterior interosseous nerve injury.

    PubMed

    Terra, Bernardo Barcellos; Sassine, Tannus Jorge; Lima, Guilherme de Freitas; Rodrigues, Leandro Marano; Padua, David Victoria Hoffmann; Nadai, Anderson de

    2016-01-01

    Fractures of the radial head and radial neck correspond to 1.7-5.4% of all fractures and approximately 30% may present associated injuries. In the literature, there are few reports of radial head fracture with posterior interosseous nerve injury. This study aimed to report a case of radial head fracture associated with posterior interosseous nerve injury.

  4. Tidal forces in Kiselev black hole

    NASA Astrophysics Data System (ADS)

    Shahzad, M. Umair; Jawad, Abdul

    2017-06-01

    The aim of this paper is to examine the tidal forces occurring in a Kiselev black hole surrounded by radiation and dust fluids. It is noted that the radial and angular components of the tidal force change the sign between event and Cauchy horizons. We solve the geodesic deviation equation for radially free-falling bodies toward Kiselev black holes. We explain the geodesic deviation vector graphically and point out the location of the event and Cauchy horizons for specific values of the radiation and dust parameters.

  5. Updates on Force Limiting Improvements

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; Scharton, Terry

    2013-01-01

    The following conventional force limiting methods currently practiced in deriving force limiting specifications assume one-dimensional translation source and load apparent masses: Simple TDOF model; Semi-empirical force limits; Apparent mass, etc.; Impedance method. Uncorrelated motion of the mounting points for components mounted on panels and correlated, but out-of-phase, motions of the support structures are important and should be considered in deriving force limiting specifications. In this presentation "rock-n-roll" motions of the components supported by panels, which leads to a more realistic force limiting specifications are discussed.

  6. Updates on Force Limiting Improvements

    NASA Technical Reports Server (NTRS)

    Kolaini, Ali R.; Scharton, Terry

    2013-01-01

    The following conventional force limiting methods currently practiced in deriving force limiting specifications assume one-dimensional translation source and load apparent masses: Simple TDOF model; Semi-empirical force limits; Apparent mass, etc.; Impedance method. Uncorrelated motion of the mounting points for components mounted on panels and correlated, but out-of-phase, motions of the support structures are important and should be considered in deriving force limiting specifications. In this presentation "rock-n-roll" motions of the components supported by panels, which leads to a more realistic force limiting specifications are discussed.

  7. Convective overstability in radially stratified accretion disks under thermal relaxation

    SciTech Connect

    Klahr, Hubert; Hubbard, Alexander

    2014-06-10

    This paper expands the stability criterion for radially stratified, vertically unstratified accretion disks incorporating thermal relaxation. We find a linear amplification of epicyclic oscillations in these disks that depends on the effective cooling time, i.e., an overstability. The growth rates of the overstability vanish for both extreme cases, e.g., infinite cooling time and instantaneous cooling, i.e., the adiabatic and fully isothermal cases. However, for thermal relaxation times τ on the order of the orbital frequency, τΩ ∼ 1, modes grow at a rate proportional to the square of the Brunt-Väisälä frequency. The overstability is based on epicyclic motions, with the thermal relaxation causing gas to heat while radially displaced inward and cool while radially displaced outward. This causes the gas to have a lower density when moving outward compared to when it moves inward, so it feels the outward-directed pressure force more strongly on that leg of the journey. We suggest the term 'convective overstability' for the phenomenon which has already been studied numerically in the nonlinear regime in the context of amplifying vortices in disks under the name 'subcritical baroclinic instability'. The aim of the present paper is to make clear that vortex formation in three-dimensional disks is not necessarily subcritical, i.e., does not need a finite perturbation, nor is it baroclinic in the sense of geophysical fluid dynamics, which requires on vertical shear. We find that convective overstability is a linear instability that will operate under a wide range of physical conditions for circumstellar disks.

  8. Precise Near-Infrared Radial Velocities

    NASA Astrophysics Data System (ADS)

    Plavchan, Peter; Gao, P.; Bottom, M.; Davison, C.; Mills, S.; Ciardi, D. R.; Brinkworth, C.; Tanner, A. M.; Beichman, C. A.; Catanzarite, J.; Crawford, S.; Wallace, J.; Mennesson, B.; Johnson, J. A.; White, R. J.; Anglada-Escudé, G.; von Braun, K.; Walp, B.; Vasisht, G.; Kane, S. R.; Prato, L. A.; NIRRVs

    2014-01-01

    We present precise radial velocity time-series from a 2.3 micron pilot survey to detect exoplanets around red, low mass, and young stars. We use the CSHELL spectrograph with an isotopic methane absorption gas cell for common optical path relative wavelength calibration at the NASA InfraRed Telescope Facility. We present an overview of our Nelder-Mead simplex optimization pipeline for extracting radial velocities. We will also present first light data at 1.6 microns from a near-infrared fiber scrambler used in tandem with our gas cell and CSHELL at IRTF. The fiber scrambler makes use of non-circular core fibers to stabilize the illumination of the slit and echelle grating against changes in seeing, focus, guiding and other sources of systematic radial velocity noise, complementing the wavelength calibration of a gas cell.

  9. Radial flow nuclear thermal rocket (RFNTR)

    DOEpatents

    Leyse, Carl F.

    1995-11-07

    A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

  10. Radial flow nuclear thermal rocket (RFNTR)

    DOEpatents

    Leyse, Carl F.

    1995-01-01

    A radial flow nuclear thermal rocket fuel assembly includes a substantially conical fuel element having an inlet side and an outlet side. An annular channel is disposed in the element for receiving a nuclear propellant, and a second, conical, channel is disposed in the element for discharging the propellant. The first channel is located radially outward from the second channel, and separated from the second channel by an annular fuel bed volume. This fuel bed volume can include a packed bed of loose fuel beads confined by a cold porous inlet frit and a hot porous exit frit. The loose fuel beads include ZrC coated ZrC-UC beads. In this manner, nuclear propellant enters the fuel assembly axially into the first channel at the inlet side of the element, flows axially across the fuel bed volume, and is discharged from the assembly by flowing radially outward from the second channel at the outlet side of the element.

  11. Radial anisotropy ambient noise tomography of volcanoes

    NASA Astrophysics Data System (ADS)

    Mordret, Aurélien; Rivet, Diane; Shapiro, Nikolai; Jaxybulatov, Kairly; Landès, Matthieu; Koulakov, Ivan; Sens-Schönfelder, Christoph

    2016-04-01

    The use of ambient seismic noise allows us to perform surface-wave tomography of targets which could hardly be imaged by other means. The frequencies involved (~ 0.5 - 20 s), somewhere in between active seismic and regular teleseismic frequency band, make possible the high resolution imaging of intermediate-size targets like volcanic edifices. Moreover, the joint inversion of Rayleigh and Love waves dispersion curves extracted from noise correlations allows us to invert for crustal radial anisotropy. We present here the two first studies of radial anisotropy on volcanoes by showing results from Lake Toba Caldera, a super-volcano in Indonesia, and from Piton de la Fournaise volcano, a hot-spot effusive volcano on the Réunion Island (Indian Ocean). We will see how radial anisotropy can be used to infer the main fabric within a magmatic system and, consequently, its dominant type of intrusion.

  12. Dispersion-free radial transmission lines

    DOEpatents

    Caporaso, George J [Livermore, CA; Nelson, Scott D [Patterson, CA

    2011-04-12

    A dispersion-free radial transmission line ("DFRTL") preferably for linear accelerators, having two plane conductors each with a central hole, and an electromagnetically permeable material ("EPM") between the two conductors and surrounding a channel connecting the two holes. At least one of the material parameters of relative magnetic permeability, relative dielectric permittivity, and axial width of the EPM is varied as a function of radius, so that the characteristic impedance of the DFRTL is held substantially constant, and pulse transmission therethrough is substantially dispersion-free. Preferably, the EPM is divided into concentric radial sections, with the varied material parameters held constant in each respective section but stepwise varied between sections as a step function of the radius. The radial widths of the concentric sections are selected so that pulse traversal time across each section is the same, and the varied material parameters of the concentric sections are selected to minimize traversal error.

  13. Manufacturing of Precision Forgings by Radial Forging

    NASA Astrophysics Data System (ADS)

    Wallner, S.; Harrer, O.; Buchmayr, B.; Hofer, F.

    2011-01-01

    Radial forging is a multi purpose incremental forging process using four tools on the same plane. It is widely used for the forming of tool steels, super alloys as well as titanium- and refractory metals. The range of application goes from reducing the diameters of shafts, tubes, stepped shafts and axels, as well as for creating internal profiles for tubes in Near-Net-Shape and Net-Shape quality. Based on actual development of a weight optimized transmission input shaft, the specific features of radial forging technology is demonstrated. Also a Finite Element Model for the simulation of the process is shown which leads to reduced pre-processing effort and reduced computing time compared to other published simulation methods for radial forging. The finite element model can be applied to quantify the effects of different forging strategies.

  14. Focal myositis presenting with radial nerve palsy.

    PubMed

    Alzagatiti, B I; Bertorini, T E; Horner, L H; Maccarino, V S; O'Brien, T

    1999-07-01

    Focal myositis is a rare inflammatory pseudotumor of skeletal muscle which usually has a benign course. We report a 56-year-old woman with a painful mass in the left arm with a radial nerve palsy. Magnetic resonance imaging (MRI) of the left arm showed a mass in the triceps muscle that was suggestive of a soft-tissue sarcoma. Electromyography showed a severe radial neuropathy involving both motor and sensory axons. An open biopsy showed focal myositis. Treatment with corticosteroids resulted in complete disappearance of the mass clinically and by MRI, without recurrence for more than 2 years. Radial nerve function also recovered completely. As a treatable cause of focal neuropathy, focal myositis should be included in the differential diagnosis of a muscle mass. Copyright 1999 John Wiley & Sons, Inc.

  15. Non-radial modes in AGB stars

    NASA Astrophysics Data System (ADS)

    Montalbán, Josefina; Trabucchi, Michele; Marigo, Paola; Wood, Peter R.; Pastorelli, Giada

    2017-09-01

    The success of asteroseismology in characterising G-K giants has motivated the extension of the same techniques to stars after the central He-burning and M-giants. The latter have been usually studied only as radial pulsators; the presence, however, of fine-structure in the period-luminosity diagram of red variables in the Magellanic Clouds could result from the presence of non-radial oscillations, offering the potential of observational indexes based on non-radial oscillations also for luminous red giants. We present here the results of a first approach aiming to identify the origin of the sub-ridges in the sequence A of the LMC red variables.

  16. Image scanning microscopy with radially polarized light

    NASA Astrophysics Data System (ADS)

    Xiao, Yun; Zhang, Yunhai; Wei, Tongda; Huang, Wei; Shi, Yaqin

    2017-03-01

    In order to improve the resolution of image scanning microscopy, we present a method based on image scanning microscopy and radially polarized light. According to the theory of image scanning microscopy, we get the effective point spread function of image scanning microscopy with the longitudinal component of radially polarized light and a 1 AU detection area, and obtain imaging results of the analyzed samples using this method. Results show that the resolution can be enhanced by 7% compared with that in image scanning microscopy with circularly polarized light, and is 1.54-fold higher than that in confocal microscopy with a pinhole of 1 AU. Additionally, the peak intensity of ISM is 1.54-fold higher than that of a confocal microscopy with a pinhole of 1 AU. In conclusion, the combination of the image scanning microscopy and the radially polarized light could improve the resolution, and it could realize high-resolution and high SNR imaging at the same time.

  17. Radial orbit error reduction and sea surface topography determination using satellite altimetry

    NASA Technical Reports Server (NTRS)

    Engelis, Theodossios

    1987-01-01

    A method is presented in satellite altimetry that attempts to simultaneously determine the geoid and sea surface topography with minimum wavelengths of about 500 km and to reduce the radial orbit error caused by geopotential errors. The modeling of the radial orbit error is made using the linearized Lagrangian perturbation theory. Secular and second order effects are also included. After a rather extensive validation of the linearized equations, alternative expressions of the radial orbit error are derived. Numerical estimates for the radial orbit error and geoid undulation error are computed using the differences of two geopotential models as potential coefficient errors, for a SEASAT orbit. To provide statistical estimates of the radial distances and the geoid, a covariance propagation is made based on the full geopotential covariance. Accuracy estimates for the SEASAT orbits are given which agree quite well with already published results. Observation equations are develped using sea surface heights and crossover discrepancies as observables. A minimum variance solution with prior information provides estimates of parameters representing the sea surface topography and corrections to the gravity field that is used for the orbit generation. The simulation results show that the method can be used to effectively reduce the radial orbit error and recover the sea surface topography.

  18. A three-dimensional chemistry/general circulation model simulation of anthropogenically derived ozone in the troposphere and its radiative climate forcing

    NASA Astrophysics Data System (ADS)

    Roelofs, Geert-Jan; Lelieveld, Jos; van Dorland, Rob

    1997-10-01

    We present results from the tropospheric chemistry/climate European Center Hamburg Model by comparing two simulations that consider a preindustrial and a contemporary emission scenario. Photochemical O3 production from anthropogenically emitted precursors contributes about 30% to the present-day tropospheric O3 content, which is roughly equal to the natural photochemical production. Transports of stratospheric O3 into the troposphere contribute about 40%. As a result of anthropogenic emissions, the O3 maximum over remote northern hemisphere (NH) areas has shifted from winter to spring, when photochemical production of O3 is relatively efficient. Over NH continents the preindustrial seasonal variability is relatively weak whereas a distinct surface O3 summer maximum appears in the contemporary simulation. In the (sub)tropical southern hemisphere (SH), anthropogenic biomass burning emissions cause an increase of O3 mixing ratios in the dry season (September-November). We calculate a relative increase in O3 mixing ratios due to anthropogenic emissions of about 30% in the pristine SH middle and high latitudes to about 100% in the polluted NH boundary layer. The model simulations suggest that the absolute increase of tropospheric O3 maximizes in the middle troposphere. Through convection, upper tropospheric O3 mixing ratios are significantly affected in the tropical regions and, during summer, in the middle and high NH latitudes. Under these conditions the radiative forcing of climate by increasing O3 is relatively large. We calculate a global and annual average radiative forcing by tropospheric O3 perturbations of 0.42 W m-2, i.e., 0.51 W m-2 in the NH and 0.33 W m-2 in the SH.

  19. Radial velocity signatures of Zeeman broadening

    NASA Astrophysics Data System (ADS)

    Reiners, A.; Shulyak, D.; Anglada-Escudé, G.; Jeffers, S. V.; Morin, J.; Zechmeister, M.; Kochukhov, O.; Piskunov, N.

    2013-04-01

    Stellar activity signatures such as spots and plages can significantly limit the search for extrasolar planets. Current models of activity-induced radial velocity (RV) signals focus on the impact of temperature contrast in spots according to which they predict the signal to diminish toward longer wavelengths. The Zeeman effect on RV measurements counteracts this: the relative importance of the Zeeman effect on RV measurements should grow with wavelength because the Zeeman displacement itself grows with λ, and because a magnetic and cool spot contributes more to the total flux at longer wavelengths. In this paper, we model the impact of active regions on stellar RV measurements including both temperature contrast in spots and line broadening by the Zeeman effect. We calculate stellar line profiles using polarized radiative transfer models including atomic and molecular Zeeman splitting over large wavelength regions from 0.5 to 2.3 μm. Our results show that the amplitude of the RV signal caused by the Zeeman effect alone can be comparable to that caused by temperature contrast; a spot magnetic field of ~1000 G can produce a similar RV amplitude as a spot temperature contrast of ~1000 K. Furthermore, the RV signal caused by cool and magnetic spots increases with wavelength, in contrast to the expectation from temperature contrast alone. We also calculate the RV signal caused by variations in average magnetic field strength from one observation to the next, for example due to a magnetic cycle, but find it unlikely that this can significantly influence the search for extrasolar planets. As an example, we derive the RV amplitude of the active M dwarf AD Leo as a function of wavelength using data from the HARPS spectrograph. Across this limited wavelength range, the RV signal does not diminish at longer wavelengths but shows evidence for the opposite behavior, consistent with a strong influence of the Zeeman effect. We conclude that the RV signal of active stars does

  20. Mapping radial features in Saturn's rings

    NASA Astrophysics Data System (ADS)

    Tiscareno, Matthew S.; Harris, B. E.

    2013-10-01

    We have carried out a comprehensive survey of the best Cassini ISS data of Saturn's main rings for the purpose of cataloguing all observed spiral density waves, spiral bending waves, and other radial and quasi-radial ring structure. Our survey has revealed a number of new features, including the first known resonant waves raised by Enceladus and Hyperion, thus increasing the number of points at which the local surface density and viscosity of the rings can be measured (cf. Tiscareno et al. 2007, Icarus). We also catalogue several wave-like features whose cause is unknown. Although images of the rings taken by the Imaging Science Subsystem (ISS) are not nominally as high-resolution as the best stellar and radio occultations, they are capable of superior signal-to-noise because of the co-adding inherent in converting a 2-D image into a 1-D "radial scan." In this common technique, as many as a thousand pixels at a given radial distance from Saturn are combined to produce a single characteristic brightness for each radial location. This process suppresses local structure, azimuthal structure, and random noise, all of which commonly decrease the sensitivity of high-resolution occultations, and causes ISS to be the optimal Cassini instrument for detecting a certain class of low-amplitude features. Finally, we employ wavelet techniques (cf. Tiscareno et al. 2007, Icarus) to elucidate subtle periodic and quasi-periodic features in the radial scan data. We will present our results in the context of a ranking of known perturbations in the rings by their resonant torque (updating Lissauer and Cuzzi 1982, AJ). We will identify the strongest expected perturbations that do not appear, and discuss whether the absence is likely to reflect a real limit of ring responsiveness, or (as with previous observations) to reflect sensitivity limits.

  1. A Predictive Model for Satellite-Derived Phytoplankton Absorption Over the Louisiana Shelf Hypoxic Zone: Effects of Nutrients and Physical Forcing

    DTIC Science & Technology

    2008-06-06

    model, the Modular Ocean Data Assimilation System size of summertime hypoxia [Mississippi River/Gulf of (MODAS) [ Carnes et aL, 1996]. Real-time...satellite- derived and model-predicted a,,, in the (a) Mississippi River I plume (Box A) and (b) Atchafalaya River plume (Box B). losi ph (m Both satellite...produc- column mixing. tivity of the Texas-Louisiana continental shelf, J Mar Syst., 11,237- 247.doi: 10.1016/SO924-7963(97)00019-5. Carnes , M. R., D. N

  2. Radial excitations of current-carrying vortices

    NASA Astrophysics Data System (ADS)

    Hartmann, Betti; Michel, Florent; Peter, Patrick

    2017-04-01

    We report on the existence of a new type of cosmic string solutions in the Witten model with U (1) × U (1) symmetry. These solutions are superconducting with radially excited condensates that exist for both gauged and ungauged currents. Our results suggest that these new configurations can be macroscopically stable, but microscopically unstable to radial perturbations. Nevertheless, they might have important consequences for the network evolution and particle emission. We discuss these effects and their possible signatures. We also comment on analogies with non-relativistic condensed matter systems where these solutions may be observable.

  3. Rotary phased radial thrust variable drive transmission

    SciTech Connect

    Shook, W.B.

    1991-09-17

    This patent describes a rotary phased radial thrust variable drive transmission located between a rotable input driving member and an output driven member which are mounted for relative rotation on a common axis. It includes radial thrust linkages carried by one of the members, and a cam unit surrounding the axis and having a selected profile, the thrust linkages carrying cam-followers for engaging the cam profile during relative rotation of the members and thrust means for engaging a mating surface on the other of the members to supply torque thereto so as to result in rotation thereof, and adjustable means for varying the profile of the cam unit.

  4. Radial Velocity Challenge at the AIUC

    NASA Astrophysics Data System (ADS)

    Zapata, Abner; Vanzi, L.; Jones, M.; Brahms, R.

    2017-09-01

    "PUCHEROS (2012, UC observatory) and FIDEOS (2016, ESO-1m La Silla Observatory), are optical echelle high-resolution spectrographs developed in the AIUC, Chile. A thorium-argon hollow-cathode emission-line lamp is used as wavelength calibration method in the two spectrographs. We show the results of the study in radial velocity stability of the instruments. Additionally, we identify the main factors that limit the performance of these spectrographs, and how we deal with them in order to achieve a better stability and precision in radial velocity measures."

  5. Radial Acceleration Relation in Rotationally Supported Galaxies

    NASA Astrophysics Data System (ADS)

    McGaugh, Stacy S.; Lelli, Federico; Schombert, James M.

    2016-11-01

    We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

  6. Plasma Signatures of Radial Field Power Dropouts

    SciTech Connect

    Lucek, E.A.; Horbury, T.S.; Balogh, A.; McComas, D.J.

    1998-10-04

    A class of small scale structures, with a near-radial magnetic field and a drop in magnetic field fluctuation power, have recently been identified in the polar solar wind. An earlier study of 24 events, each lasting for 6 hours or more, identified no clear plasma signature. In an extension of that work, radial intervals lasting for 4 hours or more (89 in total), have been used to search for a statistically significant plasma signature. It was found that, despite considerable variations between intervals, there was a small but significant drop, on average, in plasma temperature, density and {beta} during these events.

  7. Plasma signatures of radial field power dropouts

    SciTech Connect

    Lucek, E.A.; Balogh, A.; Horbury, T.S.; McComas, D.J.

    1999-06-01

    A class of small scale structures, with a near-radial magnetic field and a drop in magnetic field fluctuation power, have recently been identified in the polar solar wind. An earlier study of 24 events, each lasting for 6 hours or more, identified no clear plasma signature. In an extension of that work, radial intervals lasting for 4 hours or more (89 in total), have been used to search for a statistically significant plasma signature. It was found that, despite considerable variations between intervals, there was a small but significant drop, on average, in plasma temperature, density and {beta} during these events. {copyright} {ital 1999 American Institute of Physics.}

  8. Radial Acceleration Relation in Rotationally Supported Galaxies.

    PubMed

    McGaugh, Stacy S; Lelli, Federico; Schombert, James M

    2016-11-11

    We report a correlation between the radial acceleration traced by rotation curves and that predicted by the observed distribution of baryons. The same relation is followed by 2693 points in 153 galaxies with very different morphologies, masses, sizes, and gas fractions. The correlation persists even when dark matter dominates. Consequently, the dark matter contribution is fully specified by that of the baryons. The observed scatter is small and largely dominated by observational uncertainties. This radial acceleration relation is tantamount to a natural law for rotating galaxies.

  9. Aircraft radial-belted tire evaluation

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Stubbs, Sandy M.; Davis, Pamela A.

    1990-01-01

    An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

  10. Reconstruction for Type IV Radial Polydactyly.

    PubMed

    Wall, Lindley B; Goldfarb, Charles A

    2015-09-01

    Type IV radial polydactyly represents a thumb with an extra proximal and distal phalanx. Assessment of the thumb for surgical reconstruction includes observing thumb function, evaluating thumb size and stability, and assessing the first web space. Reconstruction includes excision of the smaller thumb, typically the radial thumb, and re-creating thumb stability and alignment by addressing tendon insertion and joint orientation. Although surgical results are satisfying and complications are uncommon, additional surgical intervention may be required over time owing to thumb malalignment or instability.

  11. VizieR Online Data Catalog: SEP stars radial velocities (Fremat+, 2017)

    NASA Astrophysics Data System (ADS)

    Fremat, Y.; Altmann, M.; Pancino, E.; Soubiran, C.; Jofre, P.; Damerdji, Y.; Heiter, U.; Royer, F.; Seabroke, G.; Sordo, R.; Blanco-Cuaresma, S.; Jasniewicz, G.; Martayan, C.; Thevenin, F.; Vallenari, A.; Blomme, R.; David, M.; Gosset, E.; Katz, D.; Viala, Y.; Boudreault, S.; Cantat-Gaudin, T.; Lobel, A.; Meisenheimer, K.; Nordlander, T.; Raskin, G.; Royer, P.; Zorec, J.

    2016-10-01

    The tables contain a description of the observations we performed with the GIRAFFE and UVES spectrographs of a sample of targets found in the South Ecliptic Pole. Radial velocities and astrophysical parameters were derived, and the variability of the RVs was assessed. (7 data files).

  12. A Neural Network for Estimation of Aortic Pressure from the Radial Artery Pressure Pulse

    DTIC Science & Technology

    2001-10-25

    from periphery to artery: a model based study, American Journal of Physiology, 1998,274:43, pp H1386-92 [9] C. Chen, E. Nevo , B Fetics, P Pak, F, Yin, L...36. [10] B Fetics, E Nevo , C. Chen, D Kass, Parametric model derivation of transfer function for noninvasive estimation of aortic pressure by radial

  13. Contractile force generation by 3D hiPSC-derived cardiac tissues is enhanced by rapid establishment of cellular interconnection in matrix with muscle-mimicking stiffness.

    PubMed

    Lee, Soah; Serpooshan, Vahid; Tong, Xinming; Venkatraman, Sneha; Lee, Meelim; Lee, Jaecheol; Chirikian, Orlando; Wu, Joseph C; Wu, Sean M; Yang, Fan

    2017-03-30

    Engineering 3D human cardiac tissues is of great importance for therapeutic and pharmaceutical applications. As cardiac tissue substitutes, extracellular matrix-derived hydrogels have been widely explored. However, they exhibit premature degradation and their stiffness is often orders of magnitude lower than that of native cardiac tissue. There are no reports on establishing interconnected cardiomyocytes in 3D hydrogels at physiologically-relevant cell density and matrix stiffness. Here we bioengineer human cardiac microtissues by encapsulating human induced pluripotent stem cell-derived cardiomyocytes (hiPSC-CMs) in chemically-crosslinked gelatin hydrogels (1.25 × 10(8)/mL) with tunable stiffness and degradation. In comparison to the cells in high stiffness (16 kPa)/slow degrading hydrogels, hiPSC-CMs in low stiffness (2 kPa)/fast degrading and intermediate stiffness (9 kPa)/intermediate degrading hydrogels exhibit increased intercellular network formation, α-actinin and connexin-43 expression, and contraction velocity. Only the 9 kPa microtissues exhibit organized sarcomeric structure and significantly increased contractile stress. This demonstrates that muscle-mimicking stiffness together with robust cellular interconnection contributes to enhancement in sarcomeric organization and contractile function of the engineered cardiac tissue. This study highlights the importance of intercellular connectivity, physiologically-relevant cell density, and matrix stiffness to best support 3D cardiac tissue engineering.

  14. Time efficient aeroelastic simulations based on radial basis functions

    NASA Astrophysics Data System (ADS)

    Liu, Wen; Huang, ChengDe; Yang, Guowei

    2017-02-01

    Aeroelasticity studies the interaction between aerodynamic forces and structural responses, and is one of the fundamental problems to be considered in the design of modern aircraft. The fluid-structure interpolation (FSI) and mesh deformation are two key issues in the CFD-CSD coupling approach (the partitioned approach), which is the mainstream numerical strategy in aeroelastic simulations. In this paper, a time efficient coupling scheme is developed based on the radial basis function interpolations. During the FSI process, the positive definite system of linear equations is constructed with the introduction of pseudo structural forces. The acting forces on the structural nodes can be calculated more efficiently via the solution of the linear system, avoiding the costly computations of the aerodynamic/structural coupling matrix. The multi-layer sequential mesh motion algorithm (MSM) is proposed to improve the efficiency of the volume mesh deformations, which is adequate for large-scale time dependent applications with frequent mesh updates. Two-dimensional mesh motion cases show that the MSM algorithm can reduce the computing cost significantly compared to the standard RBF-based method. The computations of the AGARD 445.6 wing flutter and the static deflections of the three-dimensional high-aspect-ratio aircraft demonstrate that the developed coupling scheme is applicable to both dynamic and static aeroelastic problems.

  15. Stability Analysis of Radial Turning Process for Superalloys

    NASA Astrophysics Data System (ADS)

    Jiménez, Alberto; Boto, Fernando; Irigoien, Itziar; Sierra, Basilio; Suarez, Alfredo

    2017-09-01

    Stability detection in machining processes is an essential component for the design of efficient machining processes. Automatic methods are able to determine when instability is happening and prevent possible machine failures. In this work a variety of methods are proposed for detecting stability anomalies based on the measured forces in the radial turning process of superalloys. Two different methods are proposed to determine instabilities. Each one is tested on real data obtained in the machining of Waspalloy, Haynes 282 and Inconel 718. Experimental data, in both Conventional and High Pressure Coolant (HPC) environments, are set in four different states depending on materials grain size and Hardness (LGA, LGS, SGA and SGS). Results reveal that PCA method is useful for visualization of the process and detection of anomalies in online processes.

  16. Latitudinal Dependence of the Radial IMF Component: Coronal Imprint

    NASA Technical Reports Server (NTRS)

    Suess, S. T.; Smith, E. J.

    1996-01-01

    Measurements by Ulysses have confirmed that there is no significant gradient with respect to heliomagnetic latitude in the radial component, B(sub r,) of the interplanetary magnetic field. In the corona, the plasma, beta is much less than 1, except directly above streamers, so longitudinal and latitudinal gradients in field strength will relax due to the transverse magnetic pressure gradient force as the solar wind carries magnetic flux away from the Sun. This happens quickly enough so that the field is essentially uniform by 5 - 10 solar radius, apparently remaining so as it is carried to beyond 1 AU. Here, we illustrate the coronal relaxation with a qualitative physical argument and by reference to a detailed Magneto HydroDynamics (MHD) simulation.

  17. The Sedov Blast Wave as a Radial Piston Verification Test

    DOE PAGES

    Pederson, Clark; Brown, Bart; Morgan, Nathaniel

    2016-06-22

    The Sedov blast wave is of great utility as a verification problem for hydrodynamic methods. The typical implementation uses an energized cell of finite dimensions to represent the energy point source. We avoid this approximation by directly finding the effects of the energy source as a boundary condition (BC). Furthermore, the proposed method transforms the Sedov problem into an outward moving radial piston problem with a time-varying velocity. A portion of the mesh adjacent to the origin is removed and the boundaries of this hole are forced with the velocities from the Sedov solution. This verification test is implemented onmore » two types of meshes, and convergence is shown. Our results from the typical initial condition (IC) method and the new BC method are compared.« less

  18. The Sedov Blast Wave as a Radial Piston Verification Test

    SciTech Connect

    Pederson, Clark; Brown, Bart; Morgan, Nathaniel

    2016-06-22

    The Sedov blast wave is of great utility as a verification problem for hydrodynamic methods. The typical implementation uses an energized cell of finite dimensions to represent the energy point source. We avoid this approximation by directly finding the effects of the energy source as a boundary condition (BC). Furthermore, the proposed method transforms the Sedov problem into an outward moving radial piston problem with a time-varying velocity. A portion of the mesh adjacent to the origin is removed and the boundaries of this hole are forced with the velocities from the Sedov solution. This verification test is implemented on two types of meshes, and convergence is shown. Our results from the typical initial condition (IC) method and the new BC method are compared.

  19. Testing Verlinde's emergent gravity with the radial acceleration relation

    NASA Astrophysics Data System (ADS)

    Lelli, Federico; McGaugh, Stacy S.; Schombert, James M.

    2017-06-01

    It has recently been proposed that space-time and gravity may emerge from an underlying microscopic theory. In a de Sitter space-time, such emergent gravity (EG) contains an additional gravitational force due to dark energy, which may explain the mass discrepancies observed in galactic systems without the need of dark matter. For a point mass, EG is equivalent to Modified Newtonian Dynamics (MOND). We show that this equivalence does not hold for finite-size galaxies: There are significant differences between EG and MOND in the inner regions of galaxies. We confront theoretical predictions with the empirical radial acceleration relation (RAR). We find that (i) EG is consistent with the observed RAR only if we substantially decrease the fiducial stellar mass-to-light ratios; the resulting values are in tension with other astronomical estimates; (ii) EG predicts that the residuals around the RAR should correlate with radius; such residual correlation is not observed.

  20. Radial stretch reveals distinct populations of mechanosensitive mammalian somatosensory neurons

    PubMed Central

    Bhattacharya, Martha R. C.; Bautista, Diana M.; Wu, Karin; Haeberle, Henry; Lumpkin, Ellen A.; Julius, David

    2008-01-01

    Primary afferent somatosensory neurons mediate our sense of touch in response to changes in ambient pressure. Molecules that detect and transduce thermal stimuli have been recently identified, but mechanisms underlying mechanosensation, particularly in vertebrate organisms, remain enigmatic. Traditionally, mechanically evoked responses in somatosensory neurons have been assessed one cell at a time by recording membrane currents in response to application of focal pressure, suction, or osmotic challenge. Here, we used radial stretch in combination with live-cell calcium imaging to gain a broad overview of mechanosensitive neuronal subpopulations. We found that different stretch intensities activate distinct subsets of sensory neurons as defined by size, molecular markers, or pharmacological attributes. In all subsets, stretch-evoked responses required extracellular calcium, indicating that mechanical force triggers calcium influx. This approach extends the repertoire of stimulus paradigms that can be used to examine mechanotransduction in mammalian sensory neurons, facilitating future physiological and pharmacological studies. PMID:19060212

  1. Radial breathing mode of carbon nanotubes subjected to axial pressure.

    PubMed

    Lei, Xiao-Wen; Ni, Qing-Qing; Shi, Jin-Xing; Natsuki, Toshiaki

    2011-08-11

    In this paper, a theoretical analysis of the radial breathing mode (RBM) of carbon nanotubes (CNTs) subjected to axial pressure is presented based on an elastic continuum model. Single-walled carbon nanotubes (SWCNTs) are described as an individual elastic shell and double-walled carbon nanotubes (DWCNTs) are considered to be two shells coupled through the van der Waals force. The effects of axial pressure, wave numbers and nanotube diameter on the RBM frequency are investigated in detail. The validity of these theoretical results is confirmed through the comparison of the experiment, calculation and simulation. Our results show that the RBM frequency is linearly dependent on the axial pressure and is affected by the wave numbers. We concluded that RBM frequency can be used to characterize the axial pressure acting on both ends of a CNT.

  2. Particle confinement by a radially polarized laser Bessel beam

    NASA Astrophysics Data System (ADS)

    Laredo, Gilad; Kimura, Wayne D.; Schächter, Levi

    2017-03-01

    The stable trajectory of a charged particle in an external guiding field is an essential condition for its acceleration or for forcing it to generate radiation. Examples of possible guiding devices include a solenoidal magnetic field or permanent periodic magnet in klystrons, a wiggler in free-electron lasers, the lattice of any accelerator, and finally the crystal lattice for the case of channeling radiation. We demonstrate that the trajectory of a point-charge in a radially polarized laser Bessel beam may be stable similarly to the case of a positron that bounces back and forth in the potential well generated by two adjacent atomic planes. While in the case of channeling radiation, the transverse motion is controlled by a harmonic oscillator equation, for a Bessel beam the transverse motion is controlled by the Mathieu equation. Some characteristics of the motion are presented.

  3. The Sedov Blast Wave as a Radial Piston Verification Test

    SciTech Connect

    Pederson, Clark; Brown, Bart; Morgan, Nathaniel

    2016-06-22

    The Sedov blast wave is of great utility as a verification problem for hydrodynamic methods. The typical implementation uses an energized cell of finite dimensions to represent the energy point source. We avoid this approximation by directly finding the effects of the energy source as a boundary condition (BC). Furthermore, the proposed method transforms the Sedov problem into an outward moving radial piston problem with a time-varying velocity. A portion of the mesh adjacent to the origin is removed and the boundaries of this hole are forced with the velocities from the Sedov solution. This verification test is implemented on two types of meshes, and convergence is shown. Our results from the typical initial condition (IC) method and the new BC method are compared.

  4. The phenomenological mechanochemistry of damage and radial cracking

    NASA Astrophysics Data System (ADS)

    Grinfeld, Michael

    2017-01-01

    Traditional damage theory deals with distributed microcracks rather than with individual cracks. In its simplest form, this theory adds just one additional parameter to the set of classical thermodynamic parameters of deformable solids like strain and temperature. Basically, the traditional damage theory reflects only one experimental observation: The elastic moduli become smaller with growing damage. Contrary to the traditional damage theory, the Phenomenological Mechanochemistry of Damage (PMD) uses an energetic approach; it includes, in addition to the bulk elastic energy, the energy associated with braking/recovery of chemical bonds. Therefore, in addition to the elasticity equations, it includes the equation describing evolution/dynamics of chemical bonds. With the minimum amount of physically transparent assumptions, it allows the reproduction of radial cracking patterns that are often observed in experiments and nature. In this paper, we review some earlier results and present the novel ones with emphasis on the electro- or magnetostatics ponderomotive forces.

  5. Rotor hub vibration and blade loads reduction, and energy harvesting via embedded radial oscillator

    NASA Astrophysics Data System (ADS)

    Austruy, Julien

    An embedded radial absorber is investigated to control helicopter rotor hub vibration and blade loads. The absorber is modeled as a discrete mass moving in the spanwise direction within the blade. The absorber is retained in place and tuned with a spring and a damper. The radial absorber couples with lead-lag dynamic through Coriolis forces. The embedded radial absorber coupled to the helicopter is analyzed with a comprehensive rotorcraft model. The blade is modeled as an elastic beam undergoing flap bending, lag bending and elastic torsion, and a radial degree of freedom is added for the absorber. The tuning of the embedded radial absorber to a frequency close to 3/rev with no damping is shown to reduce significantly (up to 86%) the 4/rev in-plane hub forces of a 4-bladed hingeless rotor similar to a MBB BO-105 in high speed flight. The simulation shows that the absorber modifies the in-plane blade root shears to synchronize them to cancel each other in the transmission from rotating frame to fixed frame. A design of an embedded radial absorber experiment for hub vibration control is presented and it is concluded that for such high tuning frequencies as 3/rev, it is feasible to use a regular coil spring to compensate for the steady centrifugal force. Large reduction of blade lag shear (85%) and lag bending moment (71%) is achieved by tuning the embedded radial absorber close to 1/rev (also shown for a BO-105 like helicopter in high speed flight). The absorber reduces the amplitude of the lag bending moment at 1/rev, thus reducing the blade lead-lag motion and reducing the blade drag shear and lag bending moment. Finally, the use of the embedded radial absorber is investigated as a source electrical power when combined with an electromagnetic circuit. A model of the electromagnetic system is developed and validated, and an evaluation of the amount of power harvestable for different configurations is presented. The maximum power harvested was calculated to be 133

  6. Cloud Radiative Forcing at the ARM Climate Research Facility. Part 1; Technique, Validation, and Comparison to Satellite-derived Diagnostic Quantities

    NASA Technical Reports Server (NTRS)

    Mace, Gerald G.; Benson, Sally; Sonntag, Karen L.; Kato, Seiji; Min, Qilong; Minnis, Patrick; Twohy, Cynthia H.; Poellot, Michael; Dong, Xiquan; Long, Charles; hide

    2006-01-01

    It has been hypothesized that continuous ground-based remote sensing measurements from active and passive remote sensors combined with regular soundings of the atmospheric thermodynamic structure can be combined to describe the effects of clouds on the clear sky radiation fluxes. We critically test that hypothesis in this paper and a companion paper (Part II). Using data collected at the Southern Great Plains (SGP) Atmospheric Radiation Measurement (ARM) site sponsored by the U.S. Department of Energy, we explore an analysis methodology that results in the characterization of the physical state of the atmospheric profile at time resolutions of five minutes and vertical resolutions of 90 m. The description includes thermodynamics and water vapor profile information derived by merging radiosonde soundings with ground-based data, and continues through specification of the cloud layer occurrence and microphysical and radiative properties derived from retrieval algorithms and parameterizations. The description of the atmospheric physical state includes a calculation of the infrared and clear and cloudy sky solar flux profiles. Validation of the methodology is provided by comparing the calculated fluxes with top of atmosphere (TOA) and surface flux measurements and by comparing the total column optical depths to independently derived estimates. We find over a 1-year period of comparison in overcast uniform skies, that the calculations are strongly correlated to measurements with biases in the flux quantities at the surface and TOA of less than 10% and median fractional errors ranging from 20% to as low as 2%. In the optical depth comparison for uniform overcast skies during the year 2000 where the optical depth varies over 3 orders of magnitude we find a mean positive bias of 46% with a median bias of less than 10% and a 0.89 correlation coefficient. The slope of the linear regression line for the optical depth comparison is 0.86 with a normal deviation of 20% about this

  7. Enhanced effects with scanning force microscopy

    NASA Astrophysics Data System (ADS)

    Howells, S.; Chen, T.; Gallagher, M.; Yi, L.; Sarid, D.

    1991-05-01

    A general theory that describes the operation of scanning force microscopy in the contact force regime is presented. It is shown that force derivatives along the surface of a sample produce images that can be dramatically enhanced relative to those of surface topography. For scanning tunneling microscopy atomic force microscopy configurations, the spring constant of the cantilever and the force derivatives perpendicular to the surface of the sample determine the enhancement, respectively.

  8. Activated β-catenin forces N2A cell-derived neurons back to tumor-like neuroblasts and positively correlates with a risk for human neuroblastoma.

    PubMed

    Zhi, Feng; Gong, Guangming; Xu, Yan; Zhu, Yan; Hu, Die; Yang, Yilin; Hu, Yiqiao

    2012-01-01

    Neuroblastoma is an embryonic malignancy arising from neuroblasts. The mechanisms that regulate the origination of neuroblastoma are still not very clear. In this study, we revealed that 6-bromoindirubin 3'-oxime (BIO), a specific GSK-3β inhibitor, promoted N2A cells-derived neurons to become tumor-like neuroblasts. Moreover, constitutively activated β-catenin (S33Y) also promoted this process, whereas, silencing endogenous expression of β-catenin abolished BIO-induced effects. These results implicated the potential relationship between the Wnt/β-catenin signaling and neuroblastoma formation. Indeed, we found that the amount of β-catenin in nucleus, which indicated the activation of Wnt/β-catnin signaling, was accumulated in human neuroblastoma specimens and positively correlated with clinical risk of neuroblastoma. These results give us a new sight into the neuroblastoma initiation and progression, and provide a potential drug target for neuroblastoma treatment.

  9. Comparison of Shortwave Cloud Radiative Forcing Derived from ARM SGP Surface and GOES-8 Satellite Measurements During ARESE I and ARESE II

    NASA Technical Reports Server (NTRS)

    Rapp, A. D.; Doelling, D. R.; Khaiyer, M. M.; Minnis, P.; Smith, W. L., Jr.; Nguyen, L.; Haeffelin, M. P.; Valero, F. P. J.; Asano, S.

    2001-01-01

    One of the objectives of the ARM Enhanced Shortwave Experiment (ARESE) is to investigate the absorption of solar radiation by clouds over the ARM Southern Great Plains central facility. A variety of techniques employing various combinations Of Surface, aircraft, and satellite data have been used to estimate the absorption empirically. During ARESE-I conducted during fall 1995, conflicting results were produced from different analyses of the combined datasets leading to the need for a more controlled experiment. ARESE-II was conducted during spring 2000. Improved calibrations, different sampling strategies, and broadband satellite data were all available to minimize some of the sources of uncertainty in the data. In this paper, cloud absorption or its parametric surrogates (e.g., Cess et al. 1995) are derived from collocated and coincident surface and satellite radiometer data from both ARESE-I and ARESE-II using the latest satellite and surface instrument calibrations.

  10. Radial and poloidal particle and energy fluxes in a turbulent non-Ohmic plasma: An ion-cyclotron resonance heating case

    SciTech Connect

    Pometescu, N.; Weyssow, B.

    2007-02-15

    The combined effect of the turbulence and of the external radio-frequency heating on the radial and poloidal components of the ion particle and energy fluxes in magnetically confined plasma is analyzed analytically from the drift kinetic equation. These two components of the transport are derived in terms of the thermodynamic forces and of correlations of fluctuating quantities using the methodology of neoclassical transport theory based on the tokamak standard model of confining magnetic field. The ion cyclotron heating is specifically considered since, to first order, the electron dynamics may be neglected. The formalism is applied to different types of instabilities in order to quantify the role of the heating versus turbulence on the transport.

  11. Generalized radial flow in synthetic flow systems.

    PubMed

    Bowman, Dale O; Roberts, Randall M; Holt, Robert M

    2013-01-01

    Traditional analysis methods used to determine hydraulic properties from pumping tests work well in many porous media aquifers, but they often do not work in heterogeneous and fractured-rock aquifers, producing non-plausible and erroneous results. The generalized radial flow model developed by Barker (1988) can reveal information about heterogeneity characteristics and aquifer geometry from pumping test data by way of a flow dimension parameter. The physical meaning of non-integer flow dimensions has long been a subject of debate and research. We focus on understanding and interpreting non-radial flow through high permeability conduits within fractured aquifers. We develop and simulate flow within idealized non-radial flow conduits and expand on this concept by simulating pumping in non-fractal random fields with specific properties that mimic persistent sub-radial flow responses. Our results demonstrate that non-integer flow dimensions can arise from non-fractal geometries within aquifers. We expand on these geometric concepts and successfully simulate pumping in random fields that mimic well-test responses seen in the Culebra Dolomite above the Waste Isolation Pilot Plant. © 2012, The Author(s). Groundwater © 2012, National Ground Water Association.

  12. GCFR radial blanket and shield experiment

    SciTech Connect

    Muckenthaler, F.J.; Hull, J.L.; Manning, J.J.

    1980-12-01

    This report presents integral neutron flux, energy spectra, and gamma-ray heating measurements made for the Radial Blanket and Shield Experiment at the ORNL Tower Shielding Facility as part of a continuing Gas Cooled Fast Breeder Reactor program. The experimental configurations were divided into four basic segments: a spectrum modifier inserted into the Tower Shielding Reactor II beam; blanket slabs consisting of either ThO/sub 2/ or UO/sub 2/ placed directly behind the spectrum modifier; an inner radial shield behind the blankets; and an outer radial shield to complete the mockup. The segments were added in sequence, with selected measurements made within and beyond each segment. The integral experiment was performed to provide verification of calculational methods and nuclear data used in designing a radial shield for the GCFR and determining the effectiveness of the design. The ThO/sub 2/ blanket measurements were needed to bracket the uncertainties in the nuclear cross sections for calculating both the neutron transmission through the blanket and the gamma-ray heating rates within the blanket. Measurements with a UO/sub 2/ blanket were included both as a reference for the ThO/sub 2/ analysis, neutron transmission through UO/sub 2/ having been successfully calculated in previous experiments, and to provide comparison information for other breeder reactor designs.

  13. Radial velocities of Planetary Nebulae revisited

    NASA Astrophysics Data System (ADS)

    Vázquez, Roberto; Ayala, Sandra A.; Wendolyn Blanco Cárdenas, Mónica; Contreras, María E.; Gómez-Muñoz, Marco Antonio; Guillén, Pedro F.; Olguín, Lorenzo; Ramos-Larios, Gerardo; Sabin, Laurence; Zavala, Saúl A.

    2015-08-01

    We present a new determination of radial velocities of a sample of Galactic Planetary Nebulae (PNe) using a systematic method and the same instrumental setting: the long-slit high-dispersion Manchester Echelle Spectrograph (MES) on the 2.1-m telescope at the San Pedro Mártir Observatory (OAN-SPM; Mexico). This project was inspired by the work of Schneider et al. (1983, A&AS, 52, 399), which has been an important reference during the last decades. Radial velocities of gaseous nebulae can be obtained using the central wavelength of a Gaussian fit, even when there is an expansion velocity, as expected in PNe, but with not enough resolution to see a spectral line splitting. We have used the software SHAPE, a morpho-kinematic modeling and reconstruction tool for astrophysical objects (Steffen et al. 2011, IEEE Trans. Vis. Comput. Graphics, 17, 454), to prove that non-uniform density or brightness, on an expanding shell, can lead to mistaken conclusions about the radial velocity. To determine radial velocities, we only use the spectral data in which a spectral line-splitting is seen, avoiding thus the problem of the possible biased one-Gaussian fit. Cases when this method is not recommended are discussed.This project has been supported by grant PAPIIT-DGAPA-UNAM IN107914. MWB is in grateful receipt of a DGAPA-UNAM postdoctoral scholarship. MAG acknowledges CONACYT for his graduate scholarship.

  14. MMICs with Radial Probe Transitions to Waveguides

    NASA Technical Reports Server (NTRS)

    Samoska, Lorene; Chattopadhyay, Goutam; Pukala, David; Soria, Mary; Fung, King Man; Gaier, Todd; Radisic, Vesna; Lai, Richard

    2009-01-01

    A document presents an update on the innovation reported in Integrated Radial Probe Transition From MMIC to Waveguide (NPO-43957), NASA Tech Briefs Vol. 31, No. 5 (May 2007), page 38. To recapitulate: To enable operation or testing of a monolithic microwave integrated circuit (MMIC), it is necessary to mount the MMIC in a waveguide package that typically has cross-sectional waveguide dimensions of the order of a few hundred microns. A radial probe transition between an MMIC operating at 340 GHz and a waveguide had been designed (but not yet built and tested) to be fabricated as part of a monolithic unit that would include the MMIC. The radial probe could readily be integrated with an MMIC amplifier because the design provided for fabrication of the transition on a substrate of the same material (InP) and thickness (50 m) typical of substrates of MMICs that can operate above 300 GHz. As illustrated in the updated document by drawings, photographs, and plots of test data, the concept has now been realized by designing, fabricating, and testing several MMIC/radial- probe integrated-circuit chips and designing and fabricating a waveguide package to contain each chip.

  15. Determining Enzyme Activity by Radial Diffusion

    ERIC Educational Resources Information Center

    Davis, Bill D.

    1977-01-01

    Discusses advantages of radial diffusion assay in determining presence of enzyme and/or rough approximation of amount of enzyme activities. Procedures are included for the preparation of starch-agar plates, and the application and determination of enzyme. Techniques using plant materials (homogenates, tissues, ungerminated embryos, and seedlings)…

  16. Determining Enzyme Activity by Radial Diffusion

    ERIC Educational Resources Information Center

    Davis, Bill D.

    1977-01-01

    Discusses advantages of radial diffusion assay in determining presence of enzyme and/or rough approximation of amount of enzyme activities. Procedures are included for the preparation of starch-agar plates, and the application and determination of enzyme. Techniques using plant materials (homogenates, tissues, ungerminated embryos, and seedlings)…

  17. Dual-radial cell thermionic fuel element

    NASA Astrophysics Data System (ADS)

    Terrell, Charles W.

    A dual-radial cell thermionic fuel element (TFE) has been proposed and partially evaluated. The cell has the capacity to produce considerably more power per gram of fuel than does a single-cell TFE, with a total electrical power in a fast reactor system of several hundred kWs, conservatively operated.

  18. Extended foil capacitor with radially spoked electrodes

    DOEpatents

    Foster, James C.

    1990-01-01

    An extended foil capacitor has a conductive disk electrically connected in oncrushing contact to the extended foil. A conductive paste is placed through spaces between radial spokes on the disk to electrically and mechanically connect the extended foil to the disk.

  19. Radial-Gap Motor for Ship Propulsion

    NASA Astrophysics Data System (ADS)

    Yanamoto, Toshiyuki; Yokoyama, Minoru

    The KHI team has developed radial gap high-temperature superconducting (HTS) motors of three sizes, 1 MW-class, 3 MW, and 20 MW, to be used for electric propulsion systems for ships. The volumetric torque density of the assembled 3 MW HTS motor was recorded at 40 kNm/m3 in the load test; the world's highest in the class.

  20. Force Limited Vibration Testing

    NASA Technical Reports Server (NTRS)

    Scharton, Terry; Chang, Kurng Y.

    2005-01-01

    This slide presentation reviews the concept and applications of Force Limited Vibration Testing. The goal of vibration testing of aerospace hardware is to identify problems that would result in flight failures. The commonly used aerospace vibration tests uses artificially high shaker forces and responses at the resonance frequencies of the test item. It has become common to limit the acceleration responses in the test to those predicted for the flight. This requires an analysis of the acceleration response, and requires placing accelerometers on the test item. With the advent of piezoelectric gages it has become possible to improve vibration testing. The basic equations have are reviewed. Force limits are analogous and complementary to the acceleration specifications used in conventional vibration testing. Just as the acceleration specification is the frequency spectrum envelope of the in-flight acceleration at the interface between the test item and flight mounting structure, the force limit is the envelope of the in-flight force at the interface . In force limited vibration tests, both the acceleration and force specifications are needed, and the force specification is generally based on and proportional to the acceleration specification. Therefore, force limiting does not compensate for errors in the development of the acceleration specification, e.g., too much conservatism or the lack thereof. These errors will carry over into the force specification. Since in-flight vibratory force data are scarce, force limits are often derived from coupled system analyses and impedance information obtained from measurements or finite element models (FEM). Fortunately, data on the interface forces between systems and components are now available from system acoustic and vibration tests of development test models and from a few flight experiments. Semi-empirical methods of predicting force limits are currently being developed on the basis of the limited flight and system test