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Disk
Kinds of Disk Terms modified by Disk Selected AbstractsA Relativistic Disk in Sagittarius A*ASTRONOMISCHE NACHRICHTEN, Issue S1 2003Siming Liu The detection of a mm/Sub-mm "bump" in Sgr A*'s radio spectrum suggests that at least a portion of its overall emission is produced within a compact accretion disk. This inference is strengthened by observations of strong linear polarization (at the 10 percent level) within this bump. No linear polarization has been detected yet at other wavelengths. Given that radiation from this source is produced on progressively smaller spatial scales with increasing frequency, the mm/Sub-mm bump apparently arises within a mere handful of Schwarzschild radii of the black hole. We have found that a small (10-Schwarzschild-radii) magnetized accretion disk can not only account for the spectral bump via thermal synchrotron processes, but that it can also reproduce the corresponding polarimetric results. In addition, the quiescent X-ray emission appears to be associated with synchrotron self-Comptonization, while X-ray flares detected from Sgr A* may be induced by a sudden enhancement of accretion through this disk. The hardening of the flare-state X-ray spectrum appears to favor thermal bremsstrahlung as the dominant X-ray emission mechanism during the transient event. This picture predicts correlations among the mm, IR, and X-ray flux densities, that appear to be consistent with recent multi-wavelength observations. Further evidence for such a disk in Sgr A* is provided by its radio variability. Recent monitoring of Sgr A* at cm and mm wavelengths suggests that a spectral break is manifested at 3 mm during cm/Sub-mm flares. The flat cm spectrum, combined with a weak X-ray flux in the quiescent state, rules out models in which the radio emission is produced by thermal synchrotron process in a bounded plasma. One possibility is that nonthermal particles may be produced when the large scale quasi-spherical inflow circularizes and settles down into the small accretion disk. Dissipation of kinetic energy associated with radial motion may lead to particle acceleration in shocks or via magnetic reconnection. On the other hand, the identification of a 106-day cycle in Sgr A*'s radio variability may signal a precession of the disk around a spinning black hole. The disk's characteristics imply rigid-body rotation, so the long precession period is indicative of a small black-hole spin with a spin parameter a/M around 0.1. It is interesting to note that such a small value of a/M would be favored if the nonthermal portion of Sgr A*'s spectrum is powered by a Blandford- Znajek type of process; in this situation, the observed luminosity would correspond to an outer disk radius of about 30 Schwarzschild radii. This disk structure is consistent with earlier hydrodynamical and recent MHD simulations and is implied by Sgr A*'s mm/Sub-mm spectral and polarimetric characteristics. For the disk to precess with such a long (106-day) period, the angular momentum flux flowing through it must be sufficiently small that any modulation of the total angular momentum is mostly due to its coupling with the black-hole spin. This requires that the torque exerted on the inner boundary of the disk via magnetic stresses is close to the angular momentum accretion rate associated with the infalling gas. Significant heating at the inner edge of the disk then leaves the gas marginally bounded near the black hole. A strong wind from the central region may ensue and produce a scaled down version of relativistic (possibly magnetized) jets in AGNs. [source] Development of a Model Bladder Extracellular Matrix Combining Disulfide Cross-Linked Hyaluronan with Decellularized Bladder TissueMACROMOLECULAR BIOSCIENCE, Issue 8 2006Allison L. Brown Abstract Summary: In this work we investigate the feasibility of modifying porcine-derived BAM to include HA with a view to developing a model, artificial extracellular matrix for the study of bladder cell-matrix interactions. HA-DPTH was incorporated into BAM disks and then cross-linked oxidatively to a disulfide containing hydrogel. Disks were seeded with bladder smooth muscle cells (BSMC) and UEC under three culture configurations and incubated for 3, 7, and 14 d. At each time point, matrix contraction was measured, and media supernatants assayed for cell-secreted gelatinase activity. To evaluate cell adherence and organization, triple immunofluorescent labeling of cell nuclei, actin cytoskeleton, and focal contacts was performed. HA-modified BAM exhibited a significant increase in matrix contraction and induced a higher level of cell-secreted gelatinase activity compared to unmodified BAM. Immunofluorescent labeling demonstrated that BSMCs remained adherent to both scaffold types over time. The distribution and organization of the cytoskeleton and focal contacts did not appear to be altered by the presence of HA. Interestingly, cellular infiltration into modified BAM was evident by 7 d and continued beyond 14 d, while BSMCs seeded onto unmodified BAM remained localized to the surface out to 14 d, with minimal infiltration evident only at day 28. These differences in cell infiltration support the gelatinase activity results. Increases in cell migration and matrix proteolysis in the presence of HA may be contributing factors toward BAM remodeling leading to increased matrix contraction with time. The model ECM developed in this work will be utilized for future studies aimed at elucidating the mechanisms controlling key remodeling events associated with bladder repair. Matrix contraction of cell-seeded BAM scaffolds. [source] The Vibrational Behavior of Bladed Disks in Consideration of Friction Damping and Contact ElasticityPROCEEDINGS IN APPLIED MATHEMATICS & MECHANICS, Issue 1 2005Christian Siewert Rotating turbine blading is subjected to fluctuating gas forces during operation that cause blade vibrations. One of the main tasks in the design of turbomachinery blading is the reduction of the vibration amplitudes of the blades to avoid high resonance stresses that could damage the blading. The vibration amplitudes of the blades can be reduced significantly to a reasonable amount by means of friction damping devices such as underplatform dampers. In the case of blade vibrations, relative displacements between the friction damping devices and the neighboring blades occur and friction forces are generated that provide additional damping to the structure due to the dry friction energy dissipation. In real turbomachinery applications, spatial blade vibrations caused by a complex blade geometry and distributed excitation forces acting on the airfoil accur. Therefore, a three dimensional model including an appropriate spatial contact model to predict the generalized contact forces is necessary to describe the vibrational behavior of the blading with sufficient accuracy, see [1] and [2]. In this paper the contact model presented in [2] is extended to include also local deformations in the contacts between underplatform dampers and the contact surfaces of the adjacent blades. The additional elasticity in the contact influences the resonance frequency of the coupled bladed disk assembly. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Vulnerability of the superficial zone of immature articular cartilage to compressive injuryARTHRITIS & RHEUMATISM, Issue 10 2010Bernd Rolauffs Objective The zonal composition and functioning of adult articular cartilage causes depth-dependent responses to compressive injury. In immature cartilage, shear and compressive moduli as well as collagen and sulfated glycosaminoglycan (sGAG) content also vary with depth. However, there is little understanding of the depth-dependent damage caused by injury. Since injury to immature knee joints most often causes articular cartilage lesions, this study was undertaken to characterize the zonal dependence of biomechanical, biochemical, and matrix-associated changes caused by compressive injury. Methods Disks from the superficial and deeper zones of bovine calves were biomechanically characterized. Injury to the disks was achieved by applying a final strain of 50% compression at 100%/second, followed by biomechanical recharacterization. Tissue compaction upon injury as well as sGAG density, sGAG loss, and biosynthesis were measured. Collagen fiber orientation and matrix damage were assessed using histology, diffraction-enhanced x-ray imaging, and texture analysis. Results Injured superficial zone disks showed surface disruption, tissue compaction by 20.3 ± 4.3% (mean ± SEM), and immediate biomechanical impairment that was revealed by a mean ± SEM decrease in dynamic stiffness to 7.1 ± 3.3% of the value before injury and equilibrium moduli that were below the level of detection. Tissue areas that appeared intact on histology showed clear textural alterations. Injured deeper zone disks showed collagen crimping but remained undamaged and biomechanically intact. Superficial zone disks did not lose sGAG immediately after injury, but lost 17.8 ± 1.4% of sGAG after 48 hours; deeper zone disks lost only 2.8 ± 0.3% of sGAG content. Biomechanical impairment was associated primarily with structural damage. Conclusion The soft superficial zone of immature cartilage is vulnerable to compressive injury, causing superficial matrix disruption, extensive compaction, and textural alteration, which results in immediate loss of biomechanical function. In conjunction with delayed superficial sGAG loss, these changes may predispose the articular surface to further softening and tissue damage, thus increasing the risk of development of secondary osteoarthritis. [source] Basic Fibroblast Growth Factor Coating and Endothelial Cell Seeding of a Decellularized Heparin-coated Vascular GraftARTIFICIAL ORGANS, Issue 7 2004Brian S. Conklin Abstract:, The objective of this study was to determine the effect of basic fibroblast growth factor (bFGF) coating on endothelial cell seeding and proliferation on a decellularized heparin coated vascular graft and to determine the retention of seeded cells on the graft under flow conditions. Disks of heparin coated decellularized grafts were incubated for 24 h as controls or with bFGF. Human microvascular endothelial cells (HMECs) or canine peripheral blood endothelial progenitor cells (CEPC) were seeded onto the disks and incubated for 96 h or 48 h, respectively. HMECs were also seeded onto the luminal surfaces of two heparin-coated decellularized grafts for 3 h. One graft was placed in a perfusion culture system and cultured for an additional 6 h with flow and pressure. After culturing, there were 4.7 ± 1.4 cells/mm2 HMECs on control grafts and 11.4 ± 1.4 cells/mm2 in bFGF treated grafts (P < 0.05). Likewise, with CEPCs, there were 14.8 ± 4.8 cells/mm2 in control grafts and 33.3 ± 7.3 cells/mm2 in bFGF treated grafts. After only 3 h of cell attachment, 60% of HMECs were retained in the intact graft exposed flow relative to the static control graft, which is an acceptable level. These data demonstrate that bFGF coating on the heparin bound decellularized grafts significantly increases both HMEC and dog EPC proliferation and that seeded cells are stable under perfusion conditions. [source] Preconcentration and Determination of Copper(II) Using Octadecyl Silica Membrane Disks Modified by 1,5-Diphenylcarhazide and Flame Atomic Absorption SpectrometryCHINESE JOURNAL OF CHEMISTRY, Issue 11 2007Ali MOGHIMI Abstract A simple and reproducible method for the rapid extraction and determination of trace amounts of copper(II) ions using octadecyl-bonded silica membrane disks modified by 1,5-diphenylcarbazide (DPC) and atomic absorption spectrometry was presented, which was based on complex formation on the surface of the ENVI-18 DISKTM disks followed by stripping of the retained species by minimum amounts of appropriate organic solvents. The elution was efficient and quantitative. The effect of potential interfering ions, pH, ligand amount, stripping solvent, and sample flow rate were also investigated. Under the optimal experimental conditions, the break-through volume was found to be about 1000 mL providing a preconcentration factor of 400. The maximum capacity of the disks was found to be (255±5) µg for Cu2+, and the limit of detection of the proposed method was 5 ng per 1000 mL. The method was applied to the extraction and recovery of copper in different water samples. [source] Adhesive papillae on the brachiolar arms of brachiolaria larvae in two starfishes, Asterina pectinifera and Asterias amurensis, are sensors for metamorphic inducing factor(s)DEVELOPMENT GROWTH & DIFFERENTIATION, Issue 8 2007Naoyuki Murabe It has been hypothesized by Barker that starfish brachiolaria larvae initiate metamorphosis by sensing of metamorphic inducing factor(s) with neural cells within the adhesive papillae on their brachiolar arms. We present evidence supporting Barker's hypothesis using brachiolaria larvae of the two species, Asterina pectinifera and Asterias amurensis. Brachiolaria larvae of these two species underwent metamorphosis in response to pebbles from aquaria in which adults were kept. Time-lapse analysis of A. pectinifera indicated that the pebbles were explored with adhesive papillae prior to establishment of a stable attachment for metamorphosis. Microsurgical dissections, which removed adhesive papillae, resulted in failure of the brachiolaria larvae to respond to the pebbles, but other organs such as the lateral ganglia, the oral ganglion, the adhesive disk or the adult rudiment were not required. Immunohistochemical analysis with a neuron-specific monoclonal antibody and transmission electron microscopy revealed that the adhesive papillae contained neural cells that project their processes towards the external surface of the adhesive papillae and they therefore qualify as sensory neural cells. [source] Long-span seek control system for hard disk drive without mode-switchingELECTRICAL ENGINEERING IN JAPAN, Issue 3 2010Shinji Takakura Abstract In hard disk drives (HDD) there are two control modes: the head positioning control mode and the other is the seek control mode. In the head positioning control mode, a feedback controller is optimally designed to suppress disturbances. In the long-span seek mode, a velocity feedback control system is applied in order to move the heads fast. Thus, an HDD has multiple control systems, and the head is moved to the target position while changing from one control system to the other. However, changing the control system causes a discontinuous control signal, which activates the resonant mode of an actuator. Past methods can only decrease discontinuous control, and therefore a single control system that can be used for both a seek control mode and a head positioning control mode is necessary for a narrow track pitch. In the proposed method, the feedback controller is decomposed into an integrator and a phase compensator. The VCM model is updated by the output of the phase compensator, and the integrator and the output of the velocity feedback controller control the VCM. The validity of the proposed method was confirmed by numerical and experimental results using a miniature 2.5-inch hard disk drive. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 51,60, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20935 [source] A Cobalt Film Electrode for Nitrite Determination in Natural WaterELECTROANALYSIS, Issue 24 2007Koïkoï Soropogui Abstract In this study a cobalt film electrodeposited on a copper disk (Ø=3.1,mm) was tested as electrode to measure nitrite ions in raw water. This electrode was able to determine the nitrite ions concentration in nondeaerated synthetic media and in natural water. The electrode reached a detection limit of 0.2,,mol L,1 and has a linear concentration range of 0.4 to 2,,mol L,1 NO2,. The influence of several ions such as NO3,, Cl,, SO42,, Mg2+, HCO3, and NH4+ was also tested. The electrode was used to determine the concentration of nitrite ions in a real sample. [source] Amperometry of Heparin Polyion Using a Rotating Disk Electrode Coated with a Plasticized PVC MembraneELECTROANALYSIS, Issue 2 2006Jan Langmaier Abstract Electrochemical method of detection of heparin polyion was developed based on voltammetry of heparin on a rotating glassy carbon (GC) electrode coated with a plasticized PVC membrane. The membrane was deposited on the GC disk by spin-coating technique using a mixture of solutions of PVC in tetrahydrofuran, and 1,1,-dimethylferrocene (DMFc) and hexadecyltrimethylammonium tetrakis(4-chlorophenyl)borate (HTMATPBCl) in o -nitrophenyl octyl ether. UV/vis reflection spectrometry was used to evaluate the membrane thickness, which exhibits a linear correlation with the membrane resistance measured by impedance spectroscopy. It is shown that this electrode can be used for amperometric or coulometric detection of heparin in aqueous samples of medically relevant concentrations (1,10,U mL,1), with a detection limit of 1.4,U mL,1. Evidence is provided indicating that the current determining step is the reversible adsorption of the ion-pair of heparin polyion with HTMA+ cation at the membrane/aqueous electrolyte interface, which is driven by oxidation of DMFc at the GC/membrane interface. [source] Microdimensional Polyaniline: Fabrication and Characterization of Dynamics of Charge Propagation at Microdisk ElectrodesELECTROANALYSIS, Issue 17 2004Karolina Caban Abstract We describe fabrication of microdimensional polyanilne films in a controlled manner by voltammetric potential cycling or controlled potential electrolysis on platinum microdisk electrodes. The film grows in a form of hemispherical microdeposits, and its size largely exceeds the size of a Pt microdisk. Consequently, the film covers both the Pt substrate as well as the surrounding glass seal. Since the adhering polyaniline layer is conducting, the latter situation may lead to an increase in the effective electrode surface area. The lateral growth of polyaniline films outside the microdisk has also been demonstrated by performing diagnostic voltammetric experiments with use of a double microdisk set-up in which independent polarization of each disk is feasible. Microelectrode-based chronocoulometry, that involves an uncomplicated well-defined reduction potential step starting from the emeraldine (conducting) form and ending at leucoemeraldine (nonconducting) form, yields (upon application of a sufficiently short pulse) a well-defined linear response of charge versus square root of time that is consistent with the linear effective diffusion as the predominant charge propagation mechanism. When describing the system kinetics in terms of the effective (apparent) diffusion coefficient, we expect this parameter to be on the level of 10,8,cm2 s,1 or lower. The relative changes in dynamics of charge transport are discussed with respect to the polyaniline film loading, the size of microdisk electrode, expansion of the active electrode area, and the choice of electrolyte (strong acid) anion. The results are consistent with the view that when Pt microelectrode is modified with PANI deposit exceeding the size of the microdisk substrate, it behaves in a way as if its surface area is effectively much larger than the geometric area of Pt microdisk. [source] Enhancement of Anodic Response for DMSO at Ruthenium Oxide Film Electrodes as a Result of Doping with Iron(III)ELECTROANALYSIS, Issue 2 2003Brett Abstract The oxidation of dimethyl sulfoxide (DMSO) to dimethyl sulfone (DMSO2) is representative of numerous anodic oxygen-transfer reactions of organosulfur compounds that suffer from slow kinetics at noble metal electrodes. Anodic voltammetric data for DMSO are examined at various RuO2 -film electrodes prepared by thermal deposition on titanium substrates. The response for DMSO is slightly larger at RuO2 films prepared in a flame as compared with films prepared in a furnace; however, temperature is more easily controlled in the furnace. Doping of the RuO2 films with Fe(III) further improves the sensitivity of anodic response for DMSO. Optimal response is obtained at an Fe(III)-doped RuO2 -film electrode prepared using a deposition solution of 50,mM RuCl3 and 10,mM FeCl3 in a 1,:,1 mixture of isopropanol and 12,M HCl at an annealing temperature of 450,°C. The Levich plot (i vs. ,1/2) and Koutecky-Levich plot (1/i vs. 1/,1/2) of amperometric data for the oxidation of DMSO at an Fe(III)-doped RuO2 -film electrode configured as a rotated disk are consistent with an anodic response controlled by mass-transport processes at low rotational velocities. Flow injection data demonstrate that Fe(III)-doped RuO2 -film electrodes exhibit detection capability for methionine and cysteine in addition to DMSO. Detection limits for 100-,L injections of the three compounds are ca. 3.2×10,4,mM, i.e., ca. 32,pmol. [source] Electrophoresis of a charge-regulated toroid normal to a large diskELECTROPHORESIS, Issue 2 2008Jyh-Ping Hsu Abstract The electrophoresis of a charge-regulated toroid (doughnut-shaped entity) normal to a large disk is investigated under the conditions of low surface potential and weak applied electric field. The system considered is capable of modeling the electrophoretic behavior of various types of biocolloids such as bacterial DNA, plasmid DNA, and anabaenopsis near a perfectly conducting planar wall. The influences of the size of the toroid, the separation distance between the toroid and the disk, the charged conditions on the surfaces of the toroid and the disk, and the thickness of electric double layer on the electrophoretic mobility of the toroid are discussed. The results of numerical simulation reveal that under typical conditions the electrophoretic behavior of the toroid can be different from that of an integrated entity. For instance, if the surface of the toroid carries both acidic and basic functional groups, its mobility may have a local maximum as the thickness of double layer varies. We show that the electrophoretic behavior of the toroid is different, both qualitatively and quantitatively, from that of the corresponding integrated particle (particle without hole). [source] Low-Distortion Holographic Data Storage Media Using Free-Radical Ring-Opening PolymerizationADVANCED FUNCTIONAL MATERIALS, Issue 22 2009Kyongsik Choi Abstract Holographic data storage, due to its potential to increase capacity beyond one terabyte per disk, is tipped to be one of the next generation optical data storage technologies. Polymer-based systems are leading candidates due to their high dynamic range, high sensitivities, and flexible and easy production, and yet polymerization-shrinkage-induced distortion is a major hurdle for its reliable use. In this paper, a new free radical polymerization holographic recording medium, based on low shrink cyclic allylic sulfides (LS-CASs) ring-opening monomers, is proposed and demonstrated. The percentage of volume shrinkage is measured to be 0.02%, with refractive index (RI) contrast of (1.01,±,0.5),×,10,3. The measured volume shrinkage is, to the authors' best knowledge, the best reported so far in the literature. Other parameters such as sensitivity, dynamic range, and dark reaction properties are also measured, where the values can be optimized with high RI functional groups without sacrificing the low shrinkage. [source] Cervical spondylodiscitis: A rare complication after phonatory prosthesis insertionHEAD & NECK: JOURNAL FOR THE SCIENCES & SPECIALTIES OF THE HEAD AND NECK, Issue 1 2006Andrea Bolzoni MD Abstract Background. Tracheoesophageal puncture has excellent voice rehabilitation after total laryngectomy. However, despite its easy insertion and use, severe complications have been reported. Methods. We report a case of cervical spondylodiscitis, occurring in a 67-year-old woman submitted to phonatory prosthesis insertion. After 1 month, she complained of severe cervicalgia associated with fever. Spondylodiscitis involving C6, C7, and the intervening vertebral disk with medullary compression was detected by means of imaging studies. Results. A right cervicotomy with drainage of necrotic tissue was performed, and a deepithelialized fasciocutaneous deltopectoral flap was interposed between the neopharynx-esophagus and the prevertebral fascia to protect the neurovascular axis. MR performed 1 month later showed a complete resolution of the infectious process. Conclusions. Severe neck pain after tracheoesophageal puncture should alert the physician about the possibility of a cervical spondylodiscitis. MR is the most useful imaging technique for preoperative and postoperative evaluation. When neurologic symptoms are detected, surgical exploration of the neck is mandatory. © 2005 Wiley Periodicals, Inc. Head Neck28: XXX,XXX, 2005 [source] An unsteady flow structure on a heated rotating disk under mixed convectionHEAT TRANSFER - ASIAN RESEARCH (FORMERLY HEAT TRANSFER-JAPANESE RESEARCH), Issue 6 2005Noriyuki Furuichi Abstract A flow field under mixed convection on a heated rotating disk has been measured using an ultrasonic velocity profiler (UVP). The measured velocity field is a spatio-temporal one as a function of radial coordinates and time. The objective of this paper is to clarify the vortex structure caused by the instability between buoyancy and centrifugal force. The vortex appears under typical conditions of Reynolds numbers and Grashof numbers and it moves toward the outside of the disk. This behavior can be classified into two patterns. The size of the vortex structure decreases with an increasing Reynolds number and increases with the Grashof number. The traveling velocity of the vortex increases with the Grashof number. Moreover, it decreases with an increasing Reynolds number in spite of increasing centrifugal force. According to these results, the region dominated by natural, forced, and mixed convection is classified in the relationship between Reynolds and Grashof numbers. © 2005 Wiley Periodicals, Inc. Heat Trans Asian Res, 34(6): 407,418, 2005; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/htj.20074 [source] Accuracy of the Justy II Apex locator in determining working length in simulated horizontal and vertical fracturesINTERNATIONAL ENDODONTIC JOURNAL, Issue 3 2004M. Azabal Abstract Aim, To study the effectiveness of an electronic apex locator (EAL; Justy II; Yoshida Dentcraft, Tokyo, Japan) in locating simulated horizontal and vertical fractures in single roots. Methodology, An EAL was used to measure the distance within the canal of horizontal (n = 31) and vertical (n = 31) fractures, created with a disk in single-rooted teeth. Accuracy of the EAL was evaluated by comparing the measurements with those made using a size 10 file. Data were analysed with the non-parametric Passing and Bablok method. Results, For simulated horizontal fractures, the EAL measured exactly the same length as a size 10 file, without constant or proportional errors. In vertical simulated fractures, the EAL measured (on average) with a constant error of 7.5 mm shorter than the size 10 file; the difference had a wide confidence interval (,72.3 to 2.6 mm). Conclusions, In this laboratory study, the Justy II EAL was able to determine accurately the position of simulated horizontal fractures, but was unreliable when measuring simulated vertical fractures. [source] The Reissner,Sagoci problem for a transversely isotropic half-spaceINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2006Mohammad Rahimian Abstract A transversely isotropic linear elastic half-space, z,0, with the isotropy axis parallel to the z -axis is considered. The purpose of the paper is to determine displacements and stresses fields in the interior of the half-space when a rigid circular disk of radius a completely bonded to the surface of the half-space is rotated through a constant angle ,0. The region of the surface lying out with the circle r,a, is free from stresses. This problem is a type of Reissner,Sagoci mixed boundary value problems. Using cylindrical co-ordinate system and applying Hankel integral transform in the radial direction, the problem may be changed to a system of dual integral equations. The solution of the dual integral equations is obtained by an approach analogous to Sneddon's (J. Appl. Phys. 1947; 18:130,132), so that the circumferential displacement and stress fields inside the medium are obtained analytically. The same problem has already been approached by Hanson and Puja (J. Appl. Mech. 1997; 64:692,694) by the use of integrating the point force potential functions. It is analytically proved that the present solution, although of a quite different form, is equivalent to that given by Hanson and Puja. To illustrate the solution, a few plots are provided. The displacements and the stresses in a soil deposit due to a rotationally symmetric force or boundary displacement may be obtained using the results of this paper. Copyright © 2006 John Wiley & Sons, Ltd. [source] Flow of a third grade fluid due to an accelerated diskINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 8 2010S. Asghar Abstract The magnetohydrodynamic (MHD) flow induced by non-coaxial rotation of porous disk and a third grade fluid at infinity is investigated. The disk is moving with uniform acceleration and rotating with a uniform angular velocity. Numerical solution of the governing nonlinear initial and boundary value problem is obtained. The effects of physical parameters on the velocity profiles are examined in detail. The present study shows that the constant acceleration part has a greater influence than the time part of the assumed variable velocity of the disk. Copyright © 2009 John Wiley & Sons, Ltd. [source] Numerical simulation of turbulent impinging jet on a rotating diskINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 11 2007A. Abdel-Fattah, Article first published online: 25 OCT 200 Abstract The calculations of quasi-three-dimensional momentum equations were carried out to study the influence of wall rotation on the characteristics of an impinging jet. The pressure coefficient, the mean velocity distributions and the components of Reynolds stress are calculated. The flow is assumed to be steady, incompressible and turbulent. The finite volume scheme is used to solve the continuity equation, momentum equations and k,, model equations. The flow characteristics were studied by varying rotation speed , for 0,,,167.6 rad/s, the distance from nozzle to disk (H/d) was (3, 5, 8 and 10) and the Reynolds number Re base on VJ and d was 1.45 × 104. The results showed that, the radial velocity and turbulence intensity increase by increasing the rotation speed and decrease in the impingement zone as nozzle to disk spacing increases. When the centrifugal force increases, the radial normal stresses and shear stresses increase. The location of maximum radial velocity decreases as the local velocity ratio (,) increases. The pressure coefficient depends on the centrifugal force and it decreases as the distance from nozzle to plate increases. In impingement zone and radial wall jet, the spread of flow increases as the angular velocity decreases The numerical results give good agreement with the experiment data of Minagawa and Obi (Int. J. of Heat and Fluid Flow 2004; 25:759,766). Copyright © 2006 John Wiley & Sons, Ltd. [source] A level set characteristic Galerkin finite element method for free surface flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 5 2005Ching-Long Lin Abstract This paper presents a numerical method for free surface flows that couples the incompressible Navier,Stokes equations with the level set method in the finite element framework. The implicit characteristic-Galerkin approximation together with the fractional four-step algorithm is employed to discretize the governing equations. The schemes for solving the level set evolution and reinitialization equations are verified with several benchmark cases, including stationary circle, rotation of a slotted disk and stretching of a circular fluid element. The results are compared with those calculated from the level set finite volume method of Yue et al. (Int. J. Numer. Methods Fluids 2003; 42:853,884), which employed the third-order essentially non-oscillatory (ENO) schemes for advection of the level set function in a generalized curvilinear coordinate system. The comparison indicates that the characteristic Galerkin approximation of the level set equations yields more accurate solutions. The second-order accuracy of the Navier,Stokes solver is confirmed by simulation of decay vortex. The coupled system of the Navier,Stokes and level set equations then is validated by solitary wave and broken dam problems. The simulation results are in excellent agreement with experimental data. Copyright © 2005 John Wiley & Sons, Ltd. [source] Solid-State SO2 Sensor Using a Sodium-Ionic Conductor and a Metal,Sulfide ElectrodeINTERNATIONAL JOURNAL OF APPLIED CERAMIC TECHNOLOGY, Issue 3 2006Youichi Shimizu All solid-state sulfur oxides (SOx) sensor devices combined with a sodium ionic conductor (Na5DySi4O12) disk and metal sulfide-sensing electrodes synthesized via solution routes have been systematically investigated for the detection of SO2 in the range of 20,200 ppm at 150,400°C. Among the various sulfide-sensing electrodes tested, the metal monosulfide-based electrodes gave good SO2 sensitivity at 400°C. The Pb1,xCdxS (x=0.1, 0.2)-based solid electrolyte sensor element showed the best sensing characteristics, i.e., the EMF response was almost linear to the logarithm of SO2 concentration in the range between 40 and 400 ppm, with a 90% response time to 100 ppm SO2 of about 3,15 min, and also showed high selectivity to SO2 at 400°C. [source] Development of a novel mop fanINTERNATIONAL JOURNAL OF ENERGY RESEARCH, Issue 7 2001S. B. Riffat Abstract A novel fan that operates as an air moving device as well as a filter has been investigated. The unit utilizes a brush disk, instead of bladed impellers, within a centrifugal fan casing and is known as a ,mop fan'. The performance of the mop impellers as fans was tested and their characteristic curves were found to be similar to those of centrifugal fans. The characteristics of the mop fan in terms of airflow rate, pressure, and efficiency were tested using a standard method, BS 848. The tests allowed mops of different fibre number and fibre diameter to be constructed and so optimize mop fan performance. Copyright © 2001 John Wiley & Sons, Ltd. [source] LMI approach to reliable guaranteed cost control with multiple criteria constraints: The actuator faults caseINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 8 2009Dengfeng Zhang Abstract Based on the multi-objective optimization strategy and linear matrix inequality approach, the problem of reliable guaranteed cost control with multiple criteria constraints is investigated for a class of uncertain discrete-time systems subject to actuator faults. A fault model in actuators, which considers outage or partial degradation in independent actuators, is adopted. The quadratic stability is proved to be independent of the disturbance and the upper bound of a quadratic cost index is improved. The reliable feedback controller is designed to minimize the upper bound of the quadratic cost index, place all the closed-loop poles in a specified disk, constrain the H, norm level of the disturbance attenuation into a given range and guarantee the magnitudes of control inputs less than the given bound, as well. Thus, the resulting closed-loop system can provide satisfactory stability, transient behavior, disturbance rejection level and optimized upper bound of the quadratic cost performance despite possible actuator faults. Copyright © 2008 John Wiley & Sons, Ltd. [source] Success of sildenafil treatment in neurogenic female sexual dysfunction caused by L5-S1 intervertebral disk rupture: A case reportINTERNATIONAL JOURNAL OF UROLOGY, Issue 6 2007Dean Ferrara Abstract: Female sexual dysfunction can be founded by disorders of sexual desire, arousal, orgasm, and sexual pain. Physiologic sexual dysfunction can, in many cases, be the result of impaired neurovascular tone to the clitoris and vagina. The vagina and clitoris both contain erectile tissue and phosphodiesterase type 5 (PDE5). Accordingly, the use of sildenafil, a PDE5 inhibitor, has been studied in relation to neurogenic female sexual dysfunction. The present case report addresses neurogenic female sexual dysfunction from the result of a ruptured L5-S1 intervertebral disk. The patient was treated with sildenafil, and her symptoms were recorded using a Female Sexual Function Index score. Discussion of the use of sildenafil in women, with an emphasis on female neurovascular sexual physiology and function, is reviewed. [source] Exploratory orientation data analysis with , sectionsJOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 5 2004K. Gerald Van Den Boogaart Since the domain of crystallographic orientations is three-dimensional and spherical, insightful visualization of them or visualization of related probability density functions requires (i) exploitation of the effect of a given orientation on the crystallographic axes, (ii) consideration of spherical means of the orientation probability density function, in particular with respect to one-dimensional totally geodesic submanifolds, and (iii) application of projections from the two-dimensional unit sphere onto the unit disk . The familiar crystallographic `pole figures' are actually mean values of the spherical Radon transform. The mathematical Radon transform associates a real-valued function f defined on a sphere with its mean values along one-dimensional circles with centre , the origin of the coordinate system, and spanned by two unit vectors. The family of views suggested here defines , sections in terms of simultaneous orientational relationships of two different crystal axes with two different specimen directions, such that their superposition yields a user-specified pole probability density function. Thus, the spherical averaging and the spherical projection onto the unit disk determine the distortion of the display. Commonly, spherical projections preserving either volume or angle are favoured. This rich family displays f completely, i.e. if f is given or can be determined unambiguously, then it is uniquely represented by several subsets of these views. A computer code enables the user to specify and control interactively the display of linked views, which is comprehensible as the user is in control of the display. [source] Simulation of injection-compression molding process, Part 3: Effect of process conditions on part birefringenceADVANCES IN POLYMER TECHNOLOGY, Issue 3 2002Shia-Chung Chen Abstract Simulations of the injection-compression molding (ICM) process based on a Leonov viscoelastic fluid model has been employed to study the effects of processing conditions on the birefringence development and distribution in injection-compression molded parts. A numerical algorithm combined with a modified control-volume/finite-element method is developed to predict the melt front advancement and the distributions of pressure, temperature, and flow velocity dynamically during the injection melt-filling, compression melt-filling, and postfilling stages of the entire process. Part birefringence was then calculated from residual stresses following the thermal-mechanical history of the entire molding process. Simulations of a disk part under different process conditions including compression speed, switch time from injection to compression, compression stroke, packing pressure, and postfilling time were performed to understand their effects on birefringence variation. The simulated results were also compared with those required by conventional injection molding (CIM). It has been found that an ICM part shows a significant reduction of part birefringence near the gate area as compared with CIM parts. However, ICM parts exhibit higher birefringence values near the rim of the disk. The minimum birefringence occurs around the location where injection is switched over to compression. Although longer postfilling time and higher packing pressure result in higher birefringence values, their effects are not very significant. On the other hand, higher compression speed, larger compression stroke, and shorter switch time exhibit greater effects on the increase of part birefringence. Flow-induced residual stress is the major origin of birefringence formation in the present case. The simulated birefringence for both ICM and CIM parts show good coincidence with those obtained from measurements by using a digital photoelasticity technique. © 2002 Wiley Periodicals, Inc. Adv Polym Techn 21: 177,187, 2002; Published online in Wiley Interscience (www.interscience.wiley.com). DOI 10.1002/adv.10024 [source] Labial piercing resulting in gingival recession.JOURNAL OF CLINICAL PERIODONTOLOGY, Issue 10 2002A case series Abstract Several complications of oral piercing have been recently reported in the medical and dental literature. Even though few people have had problems related to oral piercing, dentists should familiarise themselves with the potential associated oral and dental problems. We present three cases of young people with gingival recession in the mandibular incisor area related to labial piercing. The clinical examination and the dental history of the three cases revealed the relationship between the gingival recession and the presence of labial piercing. In particular, a stud in the lower lip was held in place by a metal disk on the inner labial mucosa in each case. The metal disk was in close proximity to the mandibular front teeth and it would appear that it was responsible for local trauma and recession. This case series reinforces previously reported concerns regarding the practice of piercing and the role of the dentist, both in advising patients with oral or facial piercing and in the treatment of related oral, gingival and dental problems. Zusammenfassung Durchstochene Lippen führten zu einer Retraktion Gingiva. Eine Fallserie In jüngerer Zeit wurden in der allgemein- und zahnmedizinischen Literatur eine Reihe von Komplikationen nach Durchstechen des Mundgewebes berichtet. Obwohl nur wenige Menschen Probleme nach durchstochenen Lippen bekamen, sollten sich Zahnärzte dennoch mit den potentiell mit dieser Praxis verbundenen Zahnproblemen beschäftigen. Wir stellen hier drei Fälle von jungen Menschen mit einer Retraktion der Gingiva im Bereich der mandibulären Schneidezähne vor, die auf ein Durchstechen der Lippen zurückzuführen ist. Die klinische Untersuchung und die Zahnanamnese der drei Fälle zeigte eine Verbindung zwischen der Retraktion der Gingiva und den durchstochenen Lippen. In jedem der Fälle wurde ein Stecker in der Unterlippe durch eine an der inneren Schleimhaut der Unterlippe anliegende Metallscheibe festgehalten. Die Metallscheibe lag in der direkten Umgebung der mandibulären Schneidezähne und wir gehen davon aus, das diese Scheibe für das lokale Trauma und die Retraktion der Gingiva verantwortlich war. Diese Fallserie unterstützt an früherer Stelle ausgedrückte Besorgnisse in Bezug auf das Durchstechen der Lippen und die Rolle des Zahnarztes, sowohl bei der Beratung des Patienten in Bezug auf das Durchstechen der Lippen bzw. anderer Gesichtsteile, als auch bei der Behandlung damit verbundener oraler, gingivaler oder dentaler Probleme. Résumé Piercing labial entraînant une récession gingivale. Série de cas La littérature médicale et dentaire a récemment fait état de plusieurs complications dues au piercing buccal. Bien que peu de personnes aient eu des problèmes liés au piercing buccal, les dentistes devraient se familiariser avec les potentielles complications buccales et dentaires qui lui sont associées. Nous exposons les cas de trois jeunes personnes présentant une récession gingivale dans la région incisive mandibulaire, en relation avec un piercing labial. L'examen clinique et le passé dentaire des trois cas ont mis en évidence la relation entre la récession gingivale et la présence d'un piercing labial. En particulier, dans chaque cas, un clou placé dans la lèvre inférieure était maintenu en place par un disque métallique situé sur la muqueuse labiale interne. Ce disque était à proximité des dents mandibulaires antérieures, et il semblerait qu'il ait étéà l'origine d'un traumatisme local et d'une récession. Cette série de cas renforce les préoccupations déjàévoquées dans le passé sur la pratique du piercing, ainsi que sur le rôle du dentiste, à la fois pour conseiller les patients sur le piercing buccal et facial et pour traiter les problèmes dentaires buccaux et gingivaux associés. [source] Reproducibility of 3-dimensional sonographic measurements of fetal and placental volume at gestational ages of 11,18 weeksJOURNAL OF CLINICAL ULTRASOUND, Issue 3 2007Koen Deurloo MD Abstract Purpose. Determine the reproducibility of 3D ultrasound (3DUS) measurements of fetal and placental volumes. Methods. We included 34 pregnant women between gestational weeks (GW) 11,18. Two operators independently acquired fetal and placental volumes using 3DUS. Each volume was acquired twice and stored on disk for off-line analysis. Intra- and interobserver reproducibility was expressed in the intra- and interclass correlation coefficient (intra-CC and inter-CC). In addition, the 3DUS volumes acquired by the first operator were calculated by the second and vice-versa to evaluate the effect of volume acquisition and caliper placement. A value >0.75 was considered a good agreement. Results. Fetal and placental volume measurements were successful in 97% of all cases. Between GW 11,14 and 14,18 the median fetal volume was 20.8 (5.0,35.1) and 51.7 (37.9,132.8) ml, the median placental volume was 71.3 (40.9,111.9) and 120.7 (94.2, 273.7) ml. Bland-Altman plots were used for statistical analysis. The intraobserver reproducibility was good for fetus (intra-CC: 0.99; 0.99) and placenta (intra-CC: 0.99; 0.98). Also, interobserver reproducibility was good for fetus (inter-CC 0.98) and placenta (inter-CC 0.98). In addition, regardless of the operator who acquired the volumes, the inter-CC remained good for both fetus (inter-CC: 0.99; 0.99) and placenta (inter-CC: 0.97; 0.99). Conclusion. The reproducibility of fetal and placental volume measurements by 3DUS between GW 11,18 is good. In addition, individually chosen caliper placement and volume acquisition has no effect on the calculation of either volumes. © 2007 Wiley Periodicals, Inc. J Clin Ultrasound, 2007 [source] An improved algorithm for analytical gradient evaluation in resolution-of-the-identity second-order Møller-Plesset perturbation theory: Application to alanine tetrapeptide conformational analysisJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 5 2007Robert A. Distasio JR. Abstract We present a new algorithm for analytical gradient evaluation in resolution-of-the-identity second-order Møller-Plesset perturbation theory (RI-MP2) and thoroughly assess its computational performance and chemical accuracy. This algorithm addresses the potential I/O bottlenecks associated with disk-based storage and access of the RI-MP2 t -amplitudes by utilizing a semi-direct batching approach and yields computational speed-ups of approximately 2,3 over the best conventional MP2 analytical gradient algorithms. In addition, we attempt to provide a straightforward guide to performing reliable and cost-efficient geometry optimizations at the RI-MP2 level of theory. By computing relative atomization energies for the G3/99 set and optimizing a test set of 136 equilibrium molecular structures, we demonstrate that satisfactory relative accuracy and significant computational savings can be obtained using Pople-style atomic orbital basis sets with the existing auxiliary basis expansions for RI-MP2 computations. We also show that RI-MP2 geometry optimizations reproduce molecular equilibrium structures with no significant deviations (>0.1 pm) from the predictions of conventional MP2 theory. As a chemical application, we computed the extended-globular conformational energy gap in alanine tetrapeptide at the extrapolated RI-MP2/cc-pV(TQ)Z level as 2.884, 4.414, and 4.994 kcal/mol for structures optimized using the HF, DFT (B3LYP), and RI-MP2 methodologies and the cc-pVTZ basis set, respectively. These marked energetic discrepancies originate from differential intramolecular hydrogen bonding present in the globular conformation optimized at these levels of theory and clearly demonstrate the importance of long-range correlation effects in polypeptide conformational analysis. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007 [source] | |||||||||||||||||||||||||||||||