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Sample records for finite disk manifests

  1. Uncommon Manifestations of Intervertebral Disk Pathologic Conditions.

    PubMed

    Diehn, Felix E; Maus, Timothy P; Morris, Jonathan M; Carr, Carrie M; Kotsenas, Amy L; Luetmer, Patrick H; Lehman, Vance T; Thielen, Kent R; Nassr, Ahmad; Wald, John T

    2016-01-01

    Beyond the familiar disk herniations with typical clinical features, intervertebral disk pathologic conditions can have a wide spectrum of imaging and clinical manifestations. The goal of this review is to illustrate and discuss unusual manifestations of intervertebral disk pathologic conditions that radiologists may encounter, including disk herniations in unusual locations, those with atypical imaging features, and those with uncommon pathophysiologic findings. Examples of atypical disk herniations presented include dorsal epidural, intradural, symptomatic thoracic (including giant calcified), extreme lateral (retroperitoneal), fluorine 18 fluorodeoxyglucose-avid, acute intravertebral (Schmorl node), and massive lumbar disk herniations. Examples of atypical pathophysiologic conditions covered are discal cysts, fibrocartilaginous emboli to the spinal cord, tiny calcified disks or disk-level spiculated osteophytes causing spinal cerebrospinal fluid (CSF) leak and intracranial hypotension, and pediatric acute calcific discitis. This broad gamut of disease includes a variety of sizes of disk pathologic conditions, from the tiny (eg, the minuscule calcified disks causing high-flow CSF leaks) to the extremely large (eg, giant calcified thoracic intradural disk herniations causing myelopathy). A spectrum of clinical acuity is represented, from hyperacute fibrocartilaginous emboli causing spinal cord infarct, to acute Schmorl nodes, to chronic intradural herniations. The entities included are characterized by a range of clinical courses, from the typically devastating cord infarct caused by fibrocartilaginous emboli, to the usually spontaneously resolving pediatric acute calcific discitis. Several conditions have important differential diagnostic considerations, and others have relatively diagnostic imaging findings. The pathophysiologic findings are well understood for some of these entities and poorly defined for others. Radiologists' knowledge of this broad scope of

  2. The Gravitational Force and Potential of the Finite Mestel Disk

    NASA Astrophysics Data System (ADS)

    Schulz, Earl

    2012-03-01

    Mestel determined the surface mass distribution of the finite disk for which the circular velocity is constant in the disk and found the gravitational field for points in the z = 0 plane. Here we find the exact closed form solutions for the potential and the gravitational field of this disk in cylindrical coordinates over all the space. The finite Mestel disk (FMD) is characterized by a cuspy mass distribution in the inner disk region and by an exponential distribution in the outer region of the disk. The FMD is quite different from the better known exponential disk or the untruncated Mestel disk which, being infinite in extent, are not realistic models of real spiral galaxies. In particular, the FMD requires significantly less mass to explain a measured velocity curve.

  3. Finite Axisymmetric Charged Dust Disks Sources for Conformastatic Spacetimes

    NASA Astrophysics Data System (ADS)

    González, Guillermo A.; Gutiérrez-Piñeres, Antonio C.; Ospina, Paolo A.

    2009-05-01

    An infinite family of finite axisymmetric charged dust disks is presented. The disks are obtained by solving the Einstein-Maxwell equations for conformastatic spacetimes by assuming a functional dependency between the time-like component of the electromagnetic potential and the metric potential in terms of a solution of the Laplace equation. We give solutions to the Einstein-Maxwell equations with disk sources of finite extension in which the charge density is proportional to the energy surface density. We apply the well-know ``inverse'' approach to the gravitational potential representing finite thin disks given by Gonzalez and Reina to generate conformastatic charged dust thin discs. Exact examples of conformastatic metrics with disk sources are worked out in full.

  4. Finite axisymmetric charged dust disks in conformastatic spacetimes

    SciTech Connect

    Gonzalez, Guillermo A.; Gutierrez-Pineres, Antonio C.; Ospina, Paolo A.

    2008-09-15

    An infinite family of axisymmetric charged dust disks of finite extension is presented. The disks are obtained by solving the vacuum Einstein-Maxwell equations for conformastatic spacetimes, which are characterized by only one metric function. In order to obtain the solutions, a functional relationship between the metric function and the electric potential is assumed. It is also assumed that the metric function is functionally dependent on another auxiliary function, which is taken as a solution of the Laplace equation. The solutions for the auxiliary function are then taken as given by the infinite family of generalized Kalnajs disks recently obtained by Gonzalez and Reina [G. A. Gonzalez and J. I. Reina, Mon. Not. R. Astron. Soc. 371, 1873 (2006).], expressed in terms of the oblate spheroidal coordinates and corresponding to a family of well-behaved Newtonian axisymmetric thin disks of finite radius. The obtained relativistic thin disks have a charge density that is equal, except maybe by a sign, to their mass density, in such a way that the electric and gravitational forces are in exact balance. The energy density of the disks is everywhere positive and well behaved, vanishing at the edge. Accordingly, as the disks are made of dust, their energy-momentum tensor agrees with all the energy conditions.

  5. Finite axisymmetric charged dust disks in conformastatic spacetimes

    NASA Astrophysics Data System (ADS)

    González, Guillermo A.; Gutiérrez-Piñeres, Antonio C.; Ospina, Paolo A.

    2008-09-01

    An infinite family of axisymmetric charged dust disks of finite extension is presented. The disks are obtained by solving the vacuum Einstein-Maxwell equations for conformastatic spacetimes, which are characterized by only one metric function. In order to obtain the solutions, a functional relationship between the metric function and the electric potential is assumed. It is also assumed that the metric function is functionally dependent on another auxiliary function, which is taken as a solution of the Laplace equation. The solutions for the auxiliary function are then taken as given by the infinite family of generalized Kalnajs disks recently obtained by González and Reina [G. A. González and J. I. Reina, Mon. Not. R. Astron. Soc. 371, 1873 (2006).MNRAA40035-871110.1111/j.1365-2966.2006.10819.x], expressed in terms of the oblate spheroidal coordinates and corresponding to a family of well-behaved Newtonian axisymmetric thin disks of finite radius. The obtained relativistic thin disks have a charge density that is equal, except maybe by a sign, to their mass density, in such a way that the electric and gravitational forces are in exact balance. The energy density of the disks is everywhere positive and well behaved, vanishing at the edge. Accordingly, as the disks are made of dust, their energy-momentum tensor agrees with all the energy conditions.

  6. Finite element analysis of two disk rotor system

    NASA Astrophysics Data System (ADS)

    Dixit, Harsh Kumar

    2016-05-01

    A finite element model of simple horizontal rotor system is developed for evaluating its dynamic behaviour. The model is based on Timoshenko beam element and accounts for the effect of gyroscopic couple and other rotational forces. Present rotor system consists of single shaft which is supported by bearings at both ends and two disks are mounted at different locations. The natural frequencies, mode shapes and orbits of rotating system for a specific range of rotation speed are obtained by developing a MATLAB code for solving the finite element equations of rotary system. Consequently, Campbell diagram is plotted for finding a relationship between natural whirl frequencies and rotation of the rotor.

  7. Evolution of Finite Viscous Disks with Time-independent Viscosity

    NASA Astrophysics Data System (ADS)

    Lipunova, G. V.

    2015-05-01

    We find Green functions for the accretion disk with fixed outer radius and time-independent viscosity. With the Green functions, a viscous evolution of the disk with any initial conditions can be described. Two types of inner boundary conditions are considered: the zero stress tensor and the zero accretion rate. The variable mass inflow at the outer radius can also be included. The well-known exponential decline of the accretion rate is a part of the solution with the inner zero stress tensor. The solution with the zero central accretion rate is applicable to disks around stars whose magnetosphere's boundary exceeds the corotation radius. Using the solution, the viscous evolution of disks in some binary systems can be studied. We apply the solution with zero inner stress tensor to outbursts of short-period X-ray transients during the time around the peak. It is found that for the Kramers’ regime of opacity and the initial surface density proportional to the radius, the rise time to the peak is {{t}rise}≈ 0.15 rout2/{{ν }out} and the e-folding time of the decay is {{t}exp }≈ 0.45 rout2/{{ν }out}. Comparison to non-stationary α-disks shows that both models with the same value of viscosity at the outer radius produce similar behavior on the viscous time-scale. For six bursts in X-ray novae, which exhibit fast-rise-exponential-decay and are fitted by the model, we find a way to restrict the turbulent parameter α.

  8. Finite element simulation of an artificial intervertebral disk using fiber reinforced laminated composite model.

    PubMed

    Shahmohammadi, Mehrdad; Asgharzadeh Shirazi, Hadi; Karimi, Alireza; Navidbakhsh, Mahdi

    2014-10-01

    Degeneration of intervertebral disk (IVD) has been increased in recent years. The lumbar herniation can be cured using conservative and surgical procedures. Surgery is considered after failure of conservative treatment. Partial discectomy, fusion, and total disk replacement (TDR) are also common surgical treatments for degenerative disk disease. However, due to limitations and disadvantages of the current treatments, many studies have been carried out to approach the best design of mimicking natural disk. Recently, a new method of TDRs has been introduced using nature deformation of IVD by reinforced fibers of annulus fibrosis. Nonetheless, owing to limitations of experimental works on the human body, numerical studies of IVD may help to understand load transfer and biomechanical properties within the disks with reinforced fibers. In this study, a three-dimensional (3D) finite element model of the L2-L3 disk vertebrae unit with 12 vertical fibers embedded into annulus fibrosis was constructed. The IVD was subjected to compressive force, bending moment, and axial torsion. The most important parameters of disk failures were compared to that of experimental data. The results showed that the addition of reinforced fibers into the disk invokes a significant decrease of stress in the nucleus and annulus. The findings of this study may have implications not only for developing IVDs with reinforced fibers but also for the application of fiber reinforced IVD in orthopedics surgeries as a suitable implant. PMID:24981720

  9. Finite element design study of a bladed, flat rotating disk to simulate cracking in a typical turbine disk; part II

    NASA Astrophysics Data System (ADS)

    Abdul-Aziz, Ali; Trudell, Jeffrey J.; Baakilini, George Y.

    2006-03-01

    Health management development for advanced propulsion systems and ultrasafe engine technologies continues to be among the NASA's aviation safety program goals. Health management attempts to predict, detect, and prevent safety-significant propulsion malfunctions. The primary goal is to minimize the number of propulsion system faults that leads or contribute to civil aircraft accidents. Health monitoring of essential and key components in aircraft engines such as rotors continues to interest engine makers and aviation safety government institutions to improve safety and to lower maintenance costs. Having reliable diagnostic tools for damage detection and health monitoring of rotating components is important to maintain engine safety and reliability. This paper presents finite element analyses as a means to study the durability issues of a propulsion component such as a rotor disk. The analyses are carried out under representative engine loading conditions to further investigate the application, the performance, and the functionality of a crack detection system. Rotational speeds in the range of 2000 to 10000 rpm are used. Several key design parameters such as center of mass shift, induced cracks that ranged in length from a minimum of 0.508 cm (0.2 inches) to a maximum of 5.08 cm (2.0 inches), attachment blades and typical holes within the disk are all being explored to study their influence on the crack detection system performance. Results showing relevant influence of these parameters on the performance of the disk and the crack detection systems are presented.

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

    NASA Astrophysics Data System (ADS)

    Goto, Yusuke; Tanaka, Hajime

    2015-01-01

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

  11. Finite-Element Method Analysis of Low-Frequency Wideband Array Composed of Disk Bender Transducers with Differential Connections

    NASA Astrophysics Data System (ADS)

    Yamamoto, Mitsuru; Inoue, Takeshi; Shiba, Hiroshi; Kitamura, Yuta

    2009-07-01

    In recent ocean investigations using underwater sonar transducers, low-frequency and wideband long-range sonar systems have been demanded for strong acoustic radiation and improved detective resolution capability in shallow-sea regions. We developed a disk bender transducer with a dual radiation surface as a miniaturized, light weight, low-frequency, and high-power transducer. However, there were problems in that the fractional bandwidth was small because the radiation surface was far smaller than the radiated wavelength, and the acoustic load per unit radiation area was small. Therefore, we suggest a technique to enable a wideband sonar array using differential connections of multiple disk bender transducers with different resonance frequencies to solve these problems. In this paper, we report results that endorse the above-mentioned technique obtained by finite-element method (FEM) analysis. The results confirm that this technique produces a wideband transducer array with low-frequency and high-power characteristics. We found that a wideband characteristic of more than 100% could be achieved with as a 6 dB fractional bandwidth by differential connection of disk bender transducers with three different resonance frequencies. In addition, we found that a superior horizontally oriented directivity was provided by locating the transducers in a plane symmetrical to the horizontal plane.

  12. Effect of Degeneration on Fluid–Solid Interaction within Intervertebral Disk Under Cyclic Loading – A Meta-Model Analysis of Finite Element Simulations

    PubMed Central

    Nikkhoo, Mohammad; Khalaf, Kinda; Kuo, Ya-Wen; Hsu, Yu-Chun; Haghpanahi, Mohammad; Parnianpour, Mohamad; Wang, Jaw-Lin

    2015-01-01

    The risk of low back pain resulted from cyclic loadings is greater than that resulted from prolonged static postures. Disk degeneration results in degradation of disk solid structures and decrease of water contents, which is caused by activation of matrix digestive enzymes. The mechanical responses resulted from internal solid–fluid interactions of degenerative disks to cyclic loadings are not well studied yet. The fluid–solid interactions in disks can be evaluated by mathematical models, especially the poroelastic finite element (FE) models. We developed a robust disk poroelastic FE model to analyze the effect of degeneration on solid–fluid interactions within disk subjected to cyclic loadings at different loading frequencies. A backward analysis combined with in vitro experiments was used to find the elastic modulus and hydraulic permeability of intact and enzyme-induced degenerated porcine disks. The results showed that the averaged peak-to-peak disk deformations during the in vitro cyclic tests were well fitted with limited FE simulations and a quadratic response surface regression for both disk groups. The results showed that higher loading frequency increased the intradiscal pressure, decreased the total fluid loss, and slightly increased the maximum axial stress within solid matrix. Enzyme-induced degeneration decreased the intradiscal pressure and total fluid loss, and barely changed the maximum axial stress within solid matrix. The increase of intradiscal pressure and total fluid loss with loading frequency was less sensitive after the frequency elevated to 0.1 Hz for the enzyme-induced degenerated disk. Based on this study, it is found that enzyme-induced degeneration decreases energy attenuation capability of disk, but less change the strength of disk. PMID:25674562

  13. Trigonal warping, pseudodiffusive transport, and finite-system version of the Lifshitz transition in magnetoconductance of bilayer graphene Corbino disks

    NASA Astrophysics Data System (ADS)

    Rut, Grzegorz; Rycerz, Adam

    2016-02-01

    Using the transfer matrix in the angular-momentum space we investigate the impact of trigonal warping on magnetotransport and scaling properties of a ballistic bilayer graphene in the Corbino geometry. Although the conductivity at the charge-neutrality point and zero magnetic field exhibits a one-parameter scaling, the shot-noise characteristics, quantified by the Fano factor F and the third charge-transfer cumulant R , remain pseudodiffusive. This shows that the pseudodiffusive transport regime in bilayer graphene is not related to the universal value of the conductivity but can be identified by higher charge-transfer cumulants. For Corbino disks with larger radii ratios, the conductivity is suppressed by the trigonal warping, mainly because the symmetry reduction amplifies backscattering for normal modes corresponding to angular-momentum eigenvalues ± 2 ℏ . Weak magnetic fields enhance the conductivity, reaching the maximal value near the crossover field BL=4/3 √{3 }(ℏ /e ) t't⊥[t02a (Ro-Ri) ]-1 , where t0 (t⊥) is the nearest-neighbor intralayer (interlayer) hopping integral, t' is the skew-interlayer hopping integral, and Ro (Ri) is the outer (inner) disk radius. For magnetic fields B ≳ BL we observe quasiperiodic conductance oscillations characterized by the decreasing mean value <σ > -σ0∝ BL/B , where σ0=(8 /π ) e2/h . The conductivity, as well as higher charge-transfer cumulants, show beating patterns with an envelope period proportional to √{B /BL }. This constitutes a qualitative difference between the high-field (B ≫ BL ) magnetotransport in the t'=0 case [earlier discussed in Rut and Rycerz, J. Phys.: Condens. Matter 26, 485301 (2014), 10.1088/0953-8984/26/48/485301] and in the t'≠ 0 case, providing a finite-system analog of the Lifshitz transition.

  14. Experimental verification of a non-axisymmetric displacement field predicted by finite element analysis of a composite disk subjected to an axisymmetric loading

    NASA Astrophysics Data System (ADS)

    Oliver, Stanley T.

    A finite element analysis of a circular quasi-isotropic composite disk that was clamped around its boundary and subjected to a uniform pressure was developed by the author prior to initiating this work. The analysis was performed as part of a program being developed to measure the permeability of materials. While investigating the results of the proposed configuration, it was determined that the allowable stress for the material to be tested would be exceeded close to the boundary. However, it was suggested that a pre-stress could be incorporated by tapering the clamped boundary so that, after the pressure was applied, the combined stress would fall within the material's allowable limit. Interestingly, the finite element analysis of the pre-stressed disk predicted an unexpected out-of-plane displacement that did not follow the principal material directions despite the fact that the disk was quasi-isotropic and loaded uniformly around the boundary. Further investigation revealed that this was due to variations in the terms contained in the bending stiffness matrix as a function of the angle measured relative to the principal material directions. The permeability test was subsequently adopted as part of the proposed test program and no failures have occurred to date near the boundary. However, since the initial finite element model developed for the pre-stressed condition does not accurately reflect the clamped condition currently found in practice, a more sophisticated model is needed. This dissertation focuses on the actual pre-stressed condition. After a thorough investigation is made of the bending stiffness matrix, two improved finite element models are developed using different analysis codes. The first model was developed in Nastran, mainly because the author used this package in his initial work. But the procedure to develop a nonlinear contact model for Nastran in Patran was found to be cumbersome. So, Abaqus was used because the associated pre

  15. TM01-mode microwave propagation property analysis for plasmas with disk-plate windows by a finite-difference time-domain method

    SciTech Connect

    Okamura, Yoshimasa; Yamamoto, Yoshito; Fujita, Kazuhiro; Miyoshi, Taiki; Teramoto, Koji; Kawaguchi, Hideki; Kagami, Shin; Furukawa, Masakazu

    2007-07-15

    Numerical studies of microwave propagation properties in a conical horn and an adjustable waveguides, and for plasmas generated under disk-plate windows of a 220 mm diameter and in a vacuum chamber are studied by a finite-difference time-domain (FDTD) method including plasma equations. In the numerical studies, a TM01-mode microwave of 2.45 GHz at a power of 1 kW is supplied from the top of the conical horn waveguide. In addition, numerical results by the FDTD method are compared with experimental results, and a validity of the numerical results is investigated. From the numerical results, it is found that the TM01-mode microwave changes its field shape and propagates along inner surfaces of the conical horn and the adjustable waveguides. Then electromagnetic fields of the TM01-mode microwave concentrate at the center surfaces of the disk-plate windows [quartz ({epsilon}{sub r}=3.8), alumina ({epsilon}{sub r}=9.7), and WG20 ({epsilon}{sub r}=20.0)]. A diameter of higher concentration is within 80 mm, and the orientation of electric field is almost vertical to the disk-plate window. The diameters within 80 mm are equivalent to a diameter at a higher electron density in an oxygen plasma experiment in the volume mode at 1 kW and 133 Pa with a quartz window. When heights of the adjustable waveguide are changed from 64 to 244 mm, peaks of electric fields in the heights, where microwave power is estimated to be strongly absorbed into the plasmas, appear and peak positions of the electric fields are observed periodically in surface-wave mode plasmas as well as the volume mode plasmas. Heights of the peaks increase with increasing dielectric constant and peak-to-peak distances of the peak positions decrease with increasing dielectric constant. The peak positions agree to the minimum microwave power reflections tuned by a combination of an autotuning unit and adjustable waveguide heights in experiments. Furthermore, peak positions of relatively absorbed microwave powers in

  16. Unified Nusselt- and Sherwood-number correlations in axisymmetric finite-gap stagnation and rotating-disk flows

    DOE PAGESBeta

    Coltrin, Michael E.; Kee, Robert J.

    2016-06-18

    This paper develops a unified analysis of stagnation flow heat and mass transport, considering both semi-infinite domains and finite gaps, with and without rotation of the stagnation surface. An important objective is to derive Nusselt- and Sherwood-number correlations that represent heat and mass transport at the stagnation surface. The approach is based on computationally solving the governing conservation equations in similarity form as a boundary-value problem. The formulation considers ideal gases and incompressible fluids. The correlated results depend on fluid properties in terms of Prandtl, Schmidt, and Damkohler numbers. Heterogeneous chemistry at the stagnation surface is represented as a singlemore » first-order reaction. A composite Reynolds number represents the combination of stagnation flows with and without stagnation-surface rotation.« less

  17. Herniated disk

    MedlinePlus

    ... the disk. This may place pressure on nearby nerves or the spinal cord. ... Lumbar radiculopathy; Cervical radiculopathy; Herniated intervertebral disk; Prolapsed intervertebral disk; Slipped disk; Ruptured disk; Herniated nucleus pulposus

  18. The Milky Way disk

    NASA Astrophysics Data System (ADS)

    Carraro, G.

    2015-08-01

    This review summarises the invited presentation I gave on the Milky Way disc. The idea underneath was to touch those topics that can be considered hot nowadays in the Galactic disk research: the reality of the thick disk, the spiral structure of the Milky Way, and the properties of the outer Galactic disk. A lot of work has been done in recent years on these topics, but a coherent and clear picture is still missing. Detailed studies with high quality spectroscopic data seem to support a dual Galactic disk, with a clear separation into a thin and a thick component. Much confusion and very discrepant ideas still exist concerning the spiral structure of the Milky Way. Our location in the disk makes it impossible to observe it, and we can only infer it. This process of inference is still far from being mature, and depends a lot on the selected tracers, the adopted models and their limitations, which in many cases are neither properly accounted for, nor pondered enough. Finally, there are very different opinions on the size (scale length, truncation radius) of the Galactic disk, and on the interpretation of the observed outer disk stellar populations in terms either of external entities (Monoceros, Triangulus-Andromeda, Canis Major), or as manifestations of genuine disk properties (e.g., warp and flare).

  19. Herniated Disk

    MedlinePlus

    Your backbone, or spine, is made up of 26 bones called vertebrae. In between them are soft disks filled with a jelly-like substance. These disks cushion the vertebrae and keep them in place. As you age, ...

  20. Persistent Patterns in Accretion Disks

    SciTech Connect

    Amin, Mustafa A.; Frolov, Andrei V.; /KIPAC, Menlo Park

    2006-04-03

    We present a set of new characteristic frequencies associated with accretion disks around compact objects. These frequencies arise from persistent rotating patterns in the disk that are finite in radial extent and driven purely by the gravity of the central body. Their existence depends on general relativistic corrections to orbital motion and, if observed, could be used to probe the strong gravity region around a black hole. We also discuss a possible connection to the puzzle of quasi-periodic oscillations.

  1. Optical Disks.

    ERIC Educational Resources Information Center

    Gale, John C.; And Others

    1985-01-01

    This four-article section focuses on information storage capacity of the optical disk covering the information workstation (uses microcomputer, optical disk, compact disc to provide reference information, information content, work product support); use of laser videodisc technology for dissemination of agricultural information; encoding databases…

  2. Magnetic disk

    NASA Technical Reports Server (NTRS)

    Mallinson, John C.

    1991-01-01

    Magnetic disk recording was invented in 1953 and has undergone intensive development ever since. As a result of this 38 years of development, the cost per byte and the areal density has halved and doubled, respectively every 2 to 2 1/2 years. Today, the cost per byte is lower than 10(exp -6) dollars per byte and area densities exceed 100 x 10(exp 6) bits per square inch. The recent achievements in magnetic disk recording will first be surveyed briefly. Then the principal areas of current technical development will be outlined. Finally, some comments will be made about the future of magnetic disk recording.

  3. Upper lumbar disk herniations.

    PubMed

    Cedoz, M E; Larbre, J P; Lequin, C; Fischer, G; Llorca, G

    1996-06-01

    Specific features of upper lumbar disk herniations are reviewed based on data from the literature and from a retrospective study of 24 cases treated surgically between 1982 and 1994 (seven at L1-L2 and 17 at L2-L3). Clinical manifestations are polymorphic, misleading (abdominogenital pain suggestive of a visceral or psychogenic condition, meralgia paresthetica, isolated sciatica; femoral neuralgia is uncommon) and sometimes severe (five cases of cauda equina syndrome in our study group). The diagnostic usefulness of imaging studies (radiography, myelography, computed tomography, magnetic resonance imaging) and results of surgery are discussed. The risk of misdiagnosis and the encouraging results of surgery are emphasized. PMID:8817752

  4. Disk filter

    DOEpatents

    Bergman, Werner

    1986-01-01

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  5. Disk filter

    DOEpatents

    Bergman, W.

    1985-01-09

    An electric disk filter provides a high efficiency at high temperature. A hollow outer filter of fibrous stainless steel forms the ground electrode. A refractory filter material is placed between the outer electrode and the inner electrically isolated high voltage electrode. Air flows through the outer filter surfaces through the electrified refractory filter media and between the high voltage electrodes and is removed from a space in the high voltage electrode.

  6. Rheumatic manifestations of scurvy.

    PubMed

    Ferrari, Claudia; Possemato, Niccolò; Pipitone, Nicolò; Manger, Bernhard; Salvarani, Carlo

    2015-04-01

    This paper reviews the rheumatological manifestations of scurvy, based on articles published in English from 1965 until October 2014, with a particular focus on rheumatological manifestations. Scurvy is a rare, uncommon disease in developed countries. Due to its clinical heterogeneity, the disease can easily mimic rheumatologic conditions leading to a delay in diagnosis and treatment. PMID:25854491

  7. Micromagnetic study of magnetic configurations in submicron permalloy disks

    NASA Astrophysics Data System (ADS)

    Ha, Jonathan Kin; Hertel, Riccardo; Kirschner, J.

    2003-06-01

    We report a finite-element study of magnetic configurations in submicron permalloy disks using micromagnetics principles. Depending on the disk size, many (meta)stable magnetic states such as normal and twisted onion, in-plane vortex, and various buckle states are observed. A diagram is constructed to bring out the dependence of the different remanent states on the disk diameter and thickness. It shows that the disk thickness is the decisive factor in determining whether a vortex state is energetically more favorable than an onion state, and that the disk diameter determines whether some in-plane buckling can be sustainable.

  8. Manifestly Local Theory of Vacuum Energy Sequestering.

    PubMed

    Kaloper, Nemanja; Padilla, Antonio; Stefanyszyn, David; Zahariade, George

    2016-02-01

    We present a manifestly local, diffeomorphism invariant, and locally Poincaré invariant formulation of vacuum energy sequestering. In this theory, quantum vacuum energy generated by matter loops is canceled by auxiliary fields. The auxiliary fields decouple from gravity almost completely. Their only residual effect is an a priori arbitrary, finite contribution to the curvature of the background geometry, which is radiatively stable. Its value is to be determined by a measurement, like the finite part of any radiatively stable UV-sensitive quantity in quantum field theory. PMID:26894700

  9. Haematological manifestations of lupus

    PubMed Central

    Fayyaz, Anum; Igoe, Ann; Kurien, Biji T; Danda, Debashish; James, Judith A; Stafford, Haraldine A; Scofield, R Hal

    2015-01-01

    Our purpose was to compile information on the haematological manifestations of systemic lupus erythematosus (SLE), namely leucopenia, lymphopenia, thrombocytopenia, autoimmune haemolytic anaemia (AIHA), thrombotic thrombocytopenic purpura (TTP) and myelofibrosis. During our search of the English-language MEDLINE sources, we did not place a date-of-publication constraint. Hence, we have reviewed previous as well as most recent studies with the subject heading SLE in combination with each manifestation. Neutropenia can lead to morbidity and mortality from increased susceptibility to infection. Severe neutropenia can be successfully treated with granulocyte colony-stimulating factor. While related to disease activity, there is no specific therapy for lymphopenia. Severe lymphopenia may require the use of prophylactic therapy to prevent select opportunistic infections. Isolated idiopathic thrombocytopenic purpura maybe the first manifestation of SLE by months or even years. Some manifestations of lupus occur more frequently in association with low platelet count in these patients, for example, neuropsychiatric manifestation, haemolytic anaemia, the antiphospholipid syndrome and renal disease. Thrombocytopenia can be regarded as an important prognostic indicator of survival in patients with SLE. Medical, surgical and biological treatment modalities are reviewed for this manifestation. First-line therapy remains glucocorticoids. Through our review, we conclude glucocorticoids do produce a response in majority of patients initially, but sustained response to therapy is unlikely. Glucocorticoids are used as first-line therapy in patients with SLE with AIHA, but there is no conclusive evidence to guide second-line therapy. Rituximab is promising in refractory and non-responding AIHA. TTP is not recognised as a criteria for classification of SLE, but there is a considerable overlap between the presenting features of TTP and SLE, and a few patients with SLE have concurrent

  10. Cutaneous manifestations of lupus erythematosus.

    PubMed

    Laman, S D; Provost, T T

    1994-02-01

    Lupus erythematosus is an autoimmune disease that demonstrates cutaneous, systemic, or both cutaneous and systemic manifestations. This article reviews the cutaneous manifestations of lupus erythematosus. PMID:8153399

  11. [Unusual Migraine Manifestations].

    PubMed

    Schipper, Sivan; Gantenbein, Andreas R; Sandor, Peter S

    2016-06-01

    Migraine is a complex neurologic disorder by which several systems of the central nervous system (autonomous system, affective, cognitive, sensoric and motoric system) may be affected on different levels. Around a fourth of the patients have migraine aura. The most common aura is the visual aura, followed by sensoric aura. But motoric deficits as well as deficits of higher cortical centers (disorders of thinking, orientation, coherence or concentration) may occur as well. In analogy with a headache calendar, an aura calendar can deliver important help in the diagnostic process of rare migraine manifestations and prevent underdiagnosis of unusual migraine manifestations. Complex migraine manifestations are diagnoses of exlusion, and a broad diagnostic work-up is warranted in order to exclude dangerous neurologic pathologies. There are no specific therapeutic recommendations, as there is a lack of randomized controlled studies. PMID:27269777

  12. Thermodynamics in 'Manifest Reality'

    SciTech Connect

    Hankey, Alex

    2010-12-22

    D'Espagnat's proof that the universe is not a 'strongly objective reality' demands that all physical processes are reconsidered in that light. D'Espagnat suggests a 'Veiled Reality' as a suitable alternative. The most economical way to achieve that is to demand that 'information production' at a quantum level creates the basis for self-consistent perception of a world of macroscopic, 'manifest' entities, as opposed to self-existent objects. Such a 'manifest reality' fulfils both Wheeler's attempt at an 'IT-from-BIT' programme, and Zeilinger's suggestion that 'information is primary'.

  13. Cutaneous Manifestations of ESRD

    PubMed Central

    Cronin, Antonia J.; Leslie, Kieron S.

    2014-01-01

    Summary A broad range of skin diseases occurs in patients with ESRD: from the benign and asymptomatic to the physically disabling and life-threatening. Many of them negatively impact on quality of life. Their early recognition and treatment are essential in reducing morbidity and mortality. The cutaneous manifestations can be divided into two main categories: nonspecific and specific. The nonspecific manifestations are commonly seen and include skin color changes, xerosis, half-and-half nails, and pruritus. The specific disorders include acquired perforating dermatosis, bullous dermatoses, metastatic calcification, and nephrogenic systemic fibrosis. This review article describes these conditions and considers the underlying pathophysiology, clinical presentations, diagnosis, and treatment options. PMID:24115194

  14. Manifest and Latent Variates

    ERIC Educational Resources Information Center

    Maraun, Michael D.; Halpin, Peter F.

    2008-01-01

    The clue to what latent variable models are, and to a workable account of the basis for the traditional manifest/latent variable distinction, lies in a reconsideration of the indeterminacy property of linear factor structures. In this article, the authors contend that latent variable models are not detectors of unobservable latent structures,…

  15. Destiny - Not So Manifest.

    ERIC Educational Resources Information Center

    Kerr, Clark

    Higher education in the United States is facing a period of uncertainty, confusion, conflict, and potential change, and it has little to guide it in its past experiences. For most of its three and one-third century history, it has had a manifest destiny and through the period from 1820-1870 was marked by rapid change and some student unrest. Two…

  16. Optical Disk Testing System

    NASA Astrophysics Data System (ADS)

    Manns, Basil H.

    1987-01-01

    This paper describes the development of the basics of an optical disk testing system used to test 12 inch, write once, Alcatel Thomson Gigadisk (ATG) media that are used at the Library of Congress in a pilot document storage and retrieval system. Since very little is known regarding the longevity of optical disk media and the fact that disk manufacturers are still refining processing techniques, any conclusions regarding error patterns, failure modes, or longevity may be superceded by a new "batch" of disks. Therefore, this paper focuses on the development of procedures for testing disks that can be used as the write once optical disk technology continues to advance.

  17. Procedures for shape optimization of gas turbine disks

    NASA Technical Reports Server (NTRS)

    Cheu, Tsu-Chien

    1989-01-01

    Two procedures, the feasible direction method and sequential linear programming, for shape optimization of gas turbine disks are presented. The objective of these procedures is to obtain optimal designs of turbine disks with geometric and stress constraints. The coordinates of the selected points on the disk contours are used as the design variables. Structural weight, stress and their derivatives with respect to the design variables are calculated by an efficient finite element method for design senitivity analysis. Numerical examples of the optimal designs of a disk subjected to thermo-mechanical loadings are presented to illustrate and compare the effectiveness of these two procedures.

  18. Orofacial manifestations of achondroplasia

    PubMed Central

    Rohilla, Smriti; Kaushik, Atul; Vinod, V.C.; Tanwar, Renu; Kumar, Munish

    2012-01-01

    Achondroplasia (Online Mendelian Inheritance in Man [OMIM] 100800), is considered as a form of skeletal dysplasia dwarfism that manifests with stunted stature and disproportionate limb shortening. Achondroplasia is of special interest in the field of dentistry because of its characteristic craniofacial features which include relative macrocephaly, depressed nasal bridge and maxillary hypoplasia. Presence of large head, implanted shunt, airway obstruction and difficulty in head control requires special precautions during dental management. The current case report highlights the orofacial manifestations of Achondroplasia in a young pediatric patient, along with the multidisciplinary treatment (including the dental treatment) done for the patient which also might help the general practitioners in better understanding of the condition. PMID:27298609

  19. Immunologic manifestations of autophagy

    PubMed Central

    Deretic, Vojo; Kimura, Tomonori; Timmins, Graham; Moseley, Pope; Chauhan, Santosh; Mandell, Michael

    2015-01-01

    The broad immunologic roles of autophagy span innate and adaptive immunity and are often manifested in inflammatory diseases. The immune effects of autophagy partially overlap with its roles in metabolism and cytoplasmic quality control but typically expand further afield to encompass unique immunologic adaptations. One of the best-appreciated manifestations of autophagy is protection against microbial invasion, but this is by no means limited to direct elimination of intracellular pathogens and includes a stratified array of nearly all principal immunologic processes. This Review summarizes the broad immunologic roles of autophagy. Furthermore, it uses the autophagic control of Mycobacterium tuberculosis as a paradigm to illustrate the breadth and complexity of the immune effects of autophagy. PMID:25654553

  20. [Respiratory manifestations in aspergillosis].

    PubMed

    Regimbaud, M

    1986-01-01

    Aspergillus is a genus of cosmopolitan fungi with a selective pulmonary tropism. Their pathogenic role is due either to spreading in pre-existing pulmonary cavities, or to their allergizing capacity. Cavitary sequellae of tuberculosis and suppuration, particularly frequent and important in tropical environment, are elective localization for Aspergillus colonization. Surgical treatment is nowadays the only efficient one. Allergic manifestations are a more complex problem of therapy, exclusion of allergen being difficult to get in tropical environment. PMID:3773680

  1. Neurological manifestations of malaria.

    PubMed

    Román, G C; Senanayake, N

    1992-03-01

    The involvement of the nervous system in malaria is reviewed in this paper. Cerebral malaria, the acute encephalopathy which complicates exclusively the infection by Plasmodium falciparum commonly affects children and adolescents in hyperendemic areas. Plugging of cerebral capillaries and venules by clumped, parasitized red cells causing sludging in the capillary circulation is one hypothesis to explain its pathogenesis. The other is a humoral hypothesis which proposes nonspecific, immune-mediated, inflammatory responses with release of vasoactive substances capable of producing endothelial damage and alterations of permeability. Cerebral malaria has a mortality rate up to 50%, and also a considerable longterm morbidity, particularly in children. Hypoglycemia, largely in patients treated with quinine, may complicate the cerebral symptomatology. Other central nervous manifestations of malaria include intracranial hemorrhage, cerebral arterial occlusion, and transient extrapyramidal and neuropsychiatric manifestations. A self-limiting, isolated cerebellar ataxia, presumably caused by immunological mechanisms, in patients recovering from falciparum malaria has been recognized in Sri Lanka. Malaria is a common cause of febrile seizures in the tropics, and it also contributes to the development of epilepsy in later life. Several reports of spinal cord and peripheral nerve involvement are also available. A transient muscle paralysis resembling periodic paralysis during febrile episodes of malaria has been described in some patients. The pathogenesis of these neurological manifestations remains unexplored, but offers excellent perspectives for research at a clinical as well as experimental level. PMID:1307475

  2. Burst Testing of a Superalloy Disk with a Dual Grain Structure

    NASA Technical Reports Server (NTRS)

    Gayda, John; Kantzos, Pete

    2002-01-01

    Room temperature burst testing of an advanced nickel-base superalloy disk with a dual grain structure was conducted. The disk had a fine grain bore and a coarse grain rim. The results of this test showed that the disk burst at 39,100 rpm in line with predictions based on a 2-D finite element analysis. Further, significant growth of the disk was observed before failure which was also in line with predictions.

  3. Accretion disk electrodynamics

    NASA Technical Reports Server (NTRS)

    Coroniti, F. V.

    1985-01-01

    Accretion disk electrodynamic phenomena are separable into two classes: (1) disks and coronas with turbulent magnetic fields; (2) disks and black holes which are connected to a large-scale external magnetic field. Turbulent fields may originate in an alpha-omega dynamo, provide anomalous viscous transport, and sustain an active corona by magnetic buoyancy. The large-scale field can extract energy and angular momentum from the disk and black hole, and be dynamically configured into a collimated relativistic jet.

  4. Nonlinear calculations of the time evolution of black hole accretion disks

    NASA Technical Reports Server (NTRS)

    Luo, C.

    1994-01-01

    Based on previous works on black hole accretion disks, I continue to explore the disk dynamics using the finite difference method to solve the highly nonlinear problem of time-dependent alpha disk equations. Here a radially zoned model is used to develop a computational scheme in order to accommodate functional dependence of the viscosity parameter alpha on the disk scale height and/or surface density. This work is based on the author's previous work on the steady disk structure and the linear analysis of disk dynamics to try to apply to x-ray emissions from black candidates (i.e., multiple-state spectra, instabilities, QPO's, etc.).

  5. Chemistry in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Henning, Thomas; Semenov, Dmitry

    2013-12-01

    This comprehensive review summarizes our current understanding of the evolution of gas, solids and molecular ices in protoplanetary disks. Key findings related to disk physics and chemistry, both observationally and theoretically, are highlighted. We discuss which molecular probes are used to derive gas temperature, density, ionization state, kinematics, deuterium fractionation, and study organic matter in protoplanetary disks.

  6. Optical Disk Technology.

    ERIC Educational Resources Information Center

    Abbott, George L.; And Others

    1987-01-01

    This special feature focuses on recent developments in optical disk technology. Nine articles discuss current trends, large scale image processing, data structures for optical disks, the use of computer simulators to create optical disks, videodisk use in training, interactive audio video systems, impacts on federal information policy, and…

  7. Understanding Floppy Disks.

    ERIC Educational Resources Information Center

    Valentine, Pamela

    1980-01-01

    The author describes the floppy disk with an analogy to the phonograph record, and discusses the advantages, disadvantages, and capabilities of hard-sectored and soft-sectored floppy disks. She concludes that, at present, the floppy disk will continue to be the primary choice of personal computer manufacturers and their customers. (KC)

  8. [Cutaneous manifestations of sarcoidosis].

    PubMed

    Descamps, V; Bouscarat, F

    2016-01-01

    Sarcoidosis is a systemic granulomatous disorder of unknown aetiology. Its dermatological manifestations are extremely polymorphous. They are normally classed as either specific lesions, comprising granulomas, which are generally chronic, or non-specific lesions, principally acute erythema nodosum. These signs are seen in around 25% of sarcoidosis patients. The disease may be heralded by a skin disorder. Diagnosis of cutaneous sarcoidosis provides the clinician with three problems: screening for a visceral site of the disease, determination of the prognosis, and long-term management with regular monitoring coupled with suitable therapy in the event of cosmetic or functional impairment. PMID:26804434

  9. Floppy disk utility user's guide

    NASA Technical Reports Server (NTRS)

    Akers, J. W.

    1980-01-01

    A floppy disk utility program is described which transfers programs between files on a hard disk and floppy disk. It also copies the data on one floppy disk onto another floppy disk and compares the data. The program operates on the Data General NOVA-4X under the Real Time Disk Operating System. Sample operations are given.

  10. Floppy disk utility user's guide

    NASA Technical Reports Server (NTRS)

    Akers, J. W.

    1981-01-01

    The Floppy Disk Utility Program transfers programs between files on the hard disk and floppy disk. It also copies the data on one floppy disk onto another floppy disk and compares the data. The program operates on the Data General NOVA-4X under the Real Time Disk Operating System (RDOS).

  11. GAPS IN PROTOPLANETARY DISKS AS SIGNATURES OF PLANETS. II. INCLINED DISKS

    SciTech Connect

    Jang-Condell, Hannah; Turner, Neal J.

    2013-07-20

    We examine the observational appearance of partial gaps being opened by planets in protoplanetary disks, considering the effects of the inclination relative to the line of sight. We model the disks with static {alpha}-models with detailed radiative transfer, parameterizing the shape and size of the partially cleared gaps based on the results of hydrodynamic simulations. As in previous work, starlight falling across the gap leads to high surface brightness contrasts. The gap's trough is darkened by both shadowing and cooling, relative to the uninterrupted disk. The gap's outer wall is brightened by direct illumination and also by heating, which puffs it up so that it intercepts more starlight. In this paper, we examine the effects of inclination on resolved images of disks with and without gaps at a wide range of wavelengths. The scattering surface's offset from the disk midplane creates a brightness asymmetry along the axis of inclination, making the disk's near side appear brighter than the far side in scattered light. Finite disk thickness also causes the projected distances of equidistant points on the disk surface to be smaller on the near side of the disk as compared to the far side. Consequently, the gap shoulder on the near side of the disk should appear brighter and closer to the star than on the far side. However, if the angular resolution of the observation is coarser than the width of the brightened gap shoulder, then the gap shoulder on the far side may appear brighter because of its larger apparent size. We present a formula to recover the scale height and inclination angle of an imaged disk using simple geometric arguments and measuring disk asymmetries. Resolved images of circumstellar disks have revealed clearings and gaps, such as the transitional disk in LkCa 15. Models created using our synthetic imaging attempting to match the morphology of observed scattered light images of LkCa 15 indicate that the H-band flux deficit in the inner {approx}0

  12. Ophthalmologic manifestations of celiac disease

    PubMed Central

    Martins, Thiago Gonçalves dos Santos; Costa, Ana Luiza Fontes de Azevedo; Oyamada, Maria Kiyoko; Schor, Paulo; Sipahi, Aytan Miranda

    2016-01-01

    Celiac disease is an autoimmune disorder that affects the small intestine of genetically predisposed individuals. Ophthalmic manifestations are within the extra-intestinal manifestations, and can be divided into those of autoimmune disorders or those due to absorptive disabilities. This article reviewed the ophthalmologic manifestation of celiac disease. Ophthalmic symptoms are rare, but should be investigated in patients with celiac disease and taken into consideration as the first systemic manifestation. PMID:26949627

  13. Photoevaporation and Disk Dispersal

    NASA Astrophysics Data System (ADS)

    Gorti, Uma

    2016-01-01

    Protoplanetary disks are depleted of their mass on short timescales by viscous accretion, which removes both gas and solids, and by photoevaporation which removes mainly gas. Photoevaporation may facilitate planetesimal formation by lowering the gas/dust mass ratio in disks. Disk dispersal sets constraints on planet formation timescales, and by controlling the availability of gas determines the type of planets that form in the disk. Photoevaporative wind mass loss rates are theoretically estimated to range from ~ 10-10 to 10-8 M ⊙, and disk lifetimes are typically ~ few Myr.

  14. [Ocular Manifestations in Sarcoidosis].

    PubMed

    Walscheid, K; Tappeiner, C; Heiligenhaus, A

    2016-05-01

    Sarcoidosis is an inflammatory multi-organ disease of unknown pathogenesis, characterised by non-necrotising granulomata. Sarcoidosis predominantly manifests in the lung, but any other organ may be affected. Ocular involvement is present in about 25 to 50 % of patients. The most common ocular manifestation is uveitis, especially of the anterior eye segment. If ocular sarcoidosis is suspected, interdisciplinary assessment of the patient is mandatory, including laboratory tests, chest X-ray, assessment by a specialist in internal medicine and, ideally, histological evidence of granuloma formation in a tissue specimen. Other (infectious) causes of granulomatous inflammation need to be excluded, especially tuberculosis or syphilis. For the ophthalmological assessment, detection of granulomatous lesions is of particular importance, especially by visualising chorioretinal granuloma by fluorescein and indocyanin green angiography. Cystoid macular oedema and glaucoma are the most frequent complications limiting visual acuity. Corticosteroids, which can be administered either locally or systemically, are the mainstay of therapy. Depending on the clinical course and the development of ocular complications, systemic steroid-sparing immunosuppressive medication may be indicated. PMID:27187879

  15. [Central manifestations of dystrophinopathies].

    PubMed

    Cuisset, J-M; Rivier, F

    2015-12-01

    The dystrophin gene involved in Duchenne and Becker muscular dystrophy is expressed in three main tissues resulting in clinical manifestations: skeletal muscle, heart and central nervous system. The 6 different existing dystrophins in the brain may play a role in the maturation and plasticity of neuronal synapses in particular by their functions in clustering and stabilization of different receptors at the post synaptic membrane. The possibility of an intellectual deficiency in Duchenne muscular dystrophy is known from the original description by Duchenne himself. Current data are in line with a constant cognitive impairment with a Gaussian curve shifted intellectual quotient (IQ) at -1 standard deviation from the standard population with an average IQ around 80. Clinical manifestations suggestive of a central nervous system involvement can affect all dystrophinopathies, including isolated central presentations without myopathic sign. The phenotypic spectrum appears broader and more subtle than non specific intellectual deficiency. The isolated or shared involvement of specific cognitive functions is possible (memory functions, executive functions, attention) with or without intellectual deficiency. Autism spectrum disorders are also among the encountered events. In clinical practice, it seems worth to ask for a measurement of serum creatine kinase (CK) in these different situations, keeping in mind that pure forms of central dystrophinopathies with a normal CK level have been recently reported. PMID:26773588

  16. Rheumatologic Manifestations of Sarcoidosis

    PubMed Central

    Sweiss, Nadera J.; Patterson, Karen; Sawaqed, Ray; Jabbar, Umair; Korsten, Peter; Hogarth, Kyle; Wollman, Robert; Garcia, Joe G.N.; Niewold, Timothy B.; Baughman, Robert P.

    2012-01-01

    Sarcoidosis is a systemic, clinically heterogeneous disease characterized by the development of granulomas. Any organ system can be involved, and patients may present with any number of rheumatologic symptoms. There are no U.S. Food and Drug Administration–approved therapies for the treatment of sarcoidosis. Diagnosing sarcoidosis becomes challenging, particularly when its complications cause patients’ symptoms to mimic other conditions, including polymyositis, Sjögren syndrome, or vasculitis. This review presents an overview of the etiology of and biomarkers associated with sarcoidosis. We then provide a detailed description of the rheumatologic manifestations of sarcoidosis and present a treatment algorithm based on current clinical evidence for patients with sarcoid arthritis. The discussion will focus on characteristic findings in patients with sarcoid arthritis, osseous involvement in sarcoidosis, and sarcoid myopathy. Arthritic conditions that sometimes coexist with sarcoidosis are described as well. We present two cases of sarcoidosis with rheumatologic manifestations. Our intent is to encourage a multidisciplinary, translational approach to meet the challenges and difficulties in understanding and treating sarcoidosis. PMID:20665396

  17. Laryngotracheal manifestations of rhinoscleroma.

    PubMed

    Amoils, C P; Shindo, M L

    1996-05-01

    Rhinoscleroma is a rare, chronic granulomatous disease of infective causation. It usually begins in the nose and may progress to involve the larynx and trachea and cause dysphonia, stridor, and airway obstruction. Early rhinoscleroma is usually successfully treated with oral tetracycline, yet laryngotracheal disease may require operative intervention. The disease is rare in the United States, but with an increase in immigration from endemic areas, otolaryngologists should be familiar with the management of this rare disease. Current literature contains only a few reports describing the manifestations of this disease, mostly in the form of case studies. This study is a retrospective review of our institutional experience with the management of 22 patients with rhinoscleroma, 13 of whom had laryngotracheal involvement. The focus of this report is on the clinical manifestations of laryngotracheal scleroma. All of the patients were treated with long-term antibiotics. Nine patients underwent endoscopy with or without dilation and laser excision. Three patients required emergency tracheostomy, all of whom were ultimately decannulated without any sequelae. A rational approach to management of this unusual disease is provided. PMID:8651625

  18. Burst Testing and Analysis of Superalloy Disks With a Dual Grain Microstructure

    NASA Technical Reports Server (NTRS)

    Gayda, John; Kantzos, Pete

    2006-01-01

    Elastic-plastic finite element analyses of room temperature burst tests on four superalloy disks were conducted and reported in this paper. Two alloys, Rene 104 (General Electric Aircraft Engines) and Alloy 10 (Honeywell Engines & Systems), were studied. For both alloys an advanced dual microstructure disk, fine grain bore and coarse grain rim, were analyzed and compared with conventional disks with uniform microstructures, coarse grain for Rene 104 and fine grain for Alloy 10. The analysis and experimental data were in good agreement up to burst. At burst, the analysis underestimated the speed and growth of the Rene 104 disks, but overestimated the speed and growth of the Alloy 10 disks. Fractography revealed that the Alloy 10 disks displayed significant surface microcracking and coalescence in comparison to Rene 104 disks. This phenomenon may help explain the differences between the Alloy 10 disks and the Rene 104 disks, as well as the observed deviations between analytical and experimental data at burst.

  19. High Temperature Spin Testing of a Superalloy Disk With a Dual Grain Structure

    NASA Technical Reports Server (NTRS)

    Gayda, John; Kantzos, Pete

    2002-01-01

    Comparative spin tests were run on superalloy disks at an elevated temperature to determine the benefits of a DMHT disk, with a fine grain bore and coarse grain rim, versus a traditional subsolvus disk with a fine grain structure in the bore and rim. The results of these tests showed that the DMHT disk exhibited significantly lower growth at 1500 F. Further, the results of these tests could be accurately predicted using a 2D viscoelastic finite element analysis. These results indicate DMHT technology can be used to extend disk operating temperatures when compared to traditional subsolvus heat treatment options for superalloy disks. However, additional research is required to ensure the safe operation of a DMHT disk under more realistic engine operating conditions. This includes testing to determine the burst margin and cyclic capability of DMHT disks in a spin pit, at a minimum, and ultimately running an engine test with a DMHT disk.

  20. Evolution and precession of accretion disk in tidal disruption events

    NASA Astrophysics Data System (ADS)

    Shen, R.-F.; Matzner, C. D.

    2012-12-01

    In a supermassive black hole (BH) tidal disruption event (TDE), the tidally disrupted star feeds the BH via an accretion disk. Most often it is assumed that the accretion rate history, hence the emission light curve, tracks the rate at which new debris mass falls back onto the disk, notably the t-5/3 power law. But this is not the case when the disk evolution due to viscous spreading - the driving force for accretion - is carefully considered. We construct a simple analytical model that comprehensively describes the accretion rate history across 4 different phases of the disk evolution, in the presence of mass fallback and disk wind loss. Accretion rate evolves differently in those phases which are governed by how the disk heat energy is carried away, early on by advection and later by radiation. The accretion rate can decline as steeply as t-5/3 only if copious disk wind loss is present during the early advection-cooled phase. Later, the accretion rate history is t-8/7 or shallower. These have great implications on the TDE flare light curve. A TDE accretion disk is most likely misaligned with the equatorial plane of the spinning BH. Moreover, in the TDE the accretion rate is super- or near-Eddington thus the disk is geometrically thick, for which case the BH's frame dragging effect may cause the disk precess as a solid body, which may manifest itself as quasi-periodic signal in the TDE light curve. Our disk evolution model predicts the disk precession period increases with time, typically as ∝ t. The results are applied to the recently jetted TDE flare Swift transient J1644 + 57 which shows numerous, quasi-periodic dips in its long-term X-ray light curve. As the current TDE sample increases, the identification of the disk precession signature provides a unique way of measuring BH spin and studying BH accretion physics.

  1. TF41 Engine Fan Disk Seeded Fault Crack Propagation Test

    NASA Technical Reports Server (NTRS)

    Lewicki, David G.

    2003-01-01

    Uncontained engine failures, although rare in occurrence, can have a catastrophic effect on aircraft performance and safety. Engine disk cracks can eventually lead to these type of failures. A number of techniques to detect engine disk cracks have been developed in recent years. However, these technologies have only been validated by disk spin pit tests, not actual engine tests. Due to this, a project was established to perform seeded fault engine tests on a TF41 engine disk fan. A defect was machined in the first stage fan disk of a TF41 engine. The disk was run in a spin pit to initiate a crack. Once initiated, the disk was run in an actual engine test facility. The engine was cycled by a number of start and stops with the goal of propagating the crack to disk burst through low cycle fatigue. Various crack detection techniques were installed on the engine and run real-time during the test to validate their abilities to detect disk cracks. These techniques were based on methods such as change in mass imbalance using vibration or shaft displacement, change in blade position, acoustic emission, and torsional resonance. At the completion of 4474 test cycles, the crack in the TF41 disk was determined to have grown approximately 0.025 inches. This was far less the predicted crack growth based on a fracture mechanics analysis and finite element stress analysis.

  2. Ophthalmic manifestations postlightning strike.

    PubMed

    Dhillon, Permesh Singh; Gupta, Mohit

    2015-01-01

    Various ophthalmic complications affecting the anterior and posterior segments have been identified due to lightning strike. We report the first case of an indirect lightning-induced full thickness macular hole formation in the UK as evidenced by slit lamp examination and optical coherence tomography (OCT) scan in a 77-year-old woman presenting with sudden visual loss in her right eye and thermal skin injury affecting her scalp. Her best corrected visual acuities were LogMAR 0.46 and 0.12 in the right and left eyes, respectively. There were no other ocular manifestations observed in either eye. She was initially managed conservatively with non-steroidal anti-inflammatory drug eye drops but surgery was later advised due to minimal changes in the visual acuity and macular hole on follow-up. OCT scanning is important in diagnosing macular holes, which usually warrant surgical intervention. PMID:25827914

  3. Manifesting the Quantum World

    NASA Astrophysics Data System (ADS)

    Mohrhoff, Ulrich

    2014-06-01

    In resisting attempts to explain the unity of a whole in terms of a multiplicity of interacting parts, quantum mechanics calls for an explanatory concept that proceeds in the opposite direction: from unity to multiplicity. Being part of the Scientific Image of the world, the theory concerns the process by which (the physical aspect of) what Sellars called the Manifest Image of the world comes into being. This process consists in the progressive differentiation of an intrinsically undifferentiated entity. By entering into reflexive spatial relations, this entity gives rise to (i) what looks like a multiplicity of relata if the reflexive quality of the relations is not taken into account, and (ii) what looks like a substantial expanse if the spatial quality of the relations is reified. If there is a distinctly quantum domain, it is a non-spatial and non-temporal dimension across which the transition from the unity of this entity to the multiplicity of the world takes place. Instead of being constituents of the physical world, subatomic particles, atoms, and molecules are instrumental in its manifestation. These conclusions are based on the following interpretive principle and its more direct consequences: whenever the calculation of probabilities calls for the addition of amplitudes, the distinctions we make between the alternatives lack objective reality. Applied to alternatives involving distinctions between regions of space, this principle implies that, owing to the indefiniteness of positions, the spatiotemporal differentiation of the physical world is incomplete: the existence of a real-valued spatiotemporal background is an unrealistic idealization. This guarantees the existence of observables whose values are real per se, as against "real by virtue of being indicated by the values of observables that are real per se." Applied to alternatives involving distinctions between things, it implies that, intrinsically, all fundamental particles are numerically

  4. Dynamical Structures in the Galactic Disk

    NASA Astrophysics Data System (ADS)

    Quillen, Alice C.

    2014-01-01

    Resonances with spiral density waves or the Galactic bar can cause structure in local velocity distributions (also known as phase space). Because resonances are narrow, it is possible to place tight constraints on a pattern speed or the shape of the underlying gravitational potential. Interference between multiple spiral patterns can cause localized bursts of star formation and discontinuities or kinks in the spiral arm morphology. Numerical simulations suggest that boundaries between different dominant patterns in the disk can manifest in local velocity distributions as gaps that are associated with specific orbital periods or angular momentum values. Recent studies have detected age gradients that may be associated with the appearance of spiral features such as armlets and spurs. When patterns grow or vary in speed, resonances can be swept through the disk causing changes in the velocity distributions. Evidence of resonance capture or resonance crossing can be used to place constraints on the past history of patterns in the disk. The X-shaped Galactic bulge may have been caused by stars captured into vertical resonance with the Bar. Disturbances in the Galactic disk, such as from a past merger, can cause an uneven distribution of disk stars in action angles. Subsequently the stellar distribution becomes more tightly wound in phase space. Phase wrapping can cause a series of shell like features in either real space or in a local velocity distribution. The spacing between features is dependent on the time since the disturbance.

  5. Life and reliability of rotating disks

    NASA Technical Reports Server (NTRS)

    Zaretsky, Erwin V.; Smith, Todd E.; August, Richard

    1988-01-01

    In aerospace applications, an engineer must be especially cognizant of size and weight constraints which affect design decisions. Although designing at or below the material fatigue limit may be desirable in most industrial applications, in aerospace application it is almost mandatory to design certain components for a finite life at an acceptable probability of survival. Zaretsky outlined such a methodology based in part on the work of W. Weibull (1939, 1951) and G. Lundberg and A. Palmgren (1947a, 1947b, 1952). It is the objective of this work to apply the method of Zaretsky (1987) to statistically predict the life of a generic solid disk with and without bolt holes; determine the effect of disk design variables, thermal loads, and speed on relative life; and develop a generalized equation for determining disk life by incorporating only these variables.

  6. Relativistic static thin disks: The counterrotating model

    NASA Astrophysics Data System (ADS)

    González, Guillermo A.; Espitia, Omar A.

    2003-11-01

    A detailed study is presented of the counterrotating model (CRM) for generic finite static axially symmetric thin disks with nonzero radial pressure. A general constraint over the counterrotating tangential velocities, needed to cast the surface energy-momentum tensor of the disk as the superposition of two counterrotating perfect fluids, and expressions for the energy density and pressure of the counterrotating fluids are obtained. We show that, in general, it is not possible to take the two counterrotating fluids as circulating along geodesics nor take the two counterrotating tangential velocities as equal and opposite. A simple family of disks is studied that admits some CRMs with well defined counterrotating tangential velocities and stable against radial perturbations.

  7. Superalloy Disk With Dual-Grain Structure Spin Tested

    NASA Technical Reports Server (NTRS)

    Gayda, John; Kantzos, Pete T.

    2003-01-01

    Advanced nickel-base disk alloys for future gas turbine engines will require greater temperature capability than current alloys, but they must also continue to deliver safe, reliable operation. An advanced, nickel-base disk alloy, designated Alloy 10, was selected for evaluation in NASA s Ultra Safe Propulsion Project. Early studies on small test specimens showed that heat treatments that produced a fine grain microstructure promoted high strength and long fatigue life in the bore of a disk, whereas heat treatments that produced a coarse grain microstructure promoted optimal creep and crack growth resistance in the rim of a disk. On the basis of these results, the optimal combination of performance and safety might be achieved by utilizing a heat-treatment technology that could produce a fine grain bore and coarse grain rim in a nickel-base disk. Alloy 10 disks that were given a dual microstructure heat treatment (DMHT) were obtained from NASA s Ultra-Efficient Engine Technology (UEET) Program for preliminary evaluation. Data on small test specimens machined from a DMHT disk were encouraging. However, the benefit of the dual grain structure on the performance and reliability of the entire disk still needed to be demonstrated. For this reason, a high temperature spin test of a DMHT disk was run at 20 000 rpm and 1500 F at the Balancing Company of Dayton, Ohio, under the direction of NASA Glenn Research Center personnel. The results of that test showed that the DMHT disk exhibited significantly lower crack growth than a disk with a fine grain microstructure. In addition, the results of these tests could be accurately predicted using a two-dimensional, axisymmetric finite element analysis of the DMHT disk. Although the first spin test demonstrated a significant performance advantage associated with the DMHT technology, a second spin test on the DMHT disk was run to determine burst margin. The disk burst in the web at a very high speed, over 39 000 rpm, in line with

  8. Subleading soft factor for string disk amplitudes

    NASA Astrophysics Data System (ADS)

    Schwab, Burkhard U. W.

    2014-08-01

    We investigate the behavior of superstring disk scattering amplitudes in the presence of a soft external momentum at finite string tension. We prove that there are no α'-corrections to the field theory form of the subleading soft factor S (1). At the end of this work, we also comment on the possibility to find the corresponding subleading soft factors in closed string theory using our result and the KLT relations.

  9. Ripples in disk galaxies

    SciTech Connect

    Schweizer, F.; Seitzer, P.

    1988-05-01

    Evidence is presented that ripples occur not only in ellipticals but also in disk galaxies of Hubble types S0, S0/Sa, and Sa, and probably even in the Sbc galaxy NGC 3310. It is argued that the ripples cannot usually have resulted from transient spiral waves or other forced vibrations in existing disks, but instead consist of extraneous sheetlike matter. The frequent presence of major disk-shaped companions suggests that ripple material may be acquired not only through wholesale mergers but also through mass transfer from neighbor galaxies. The implications of ripples in early-type disk galaxies are addressed. 40 references.

  10. Glass rupture disk

    DOEpatents

    Glass, S. Jill; Nicolaysen, Scott D.; Beauchamp, Edwin K.

    2002-01-01

    A frangible rupture disk and mounting apparatus for use in blocking fluid flow, generally in a fluid conducting conduit such as a well casing, a well tubing string or other conduits within subterranean boreholes. The disk can also be utilized in above-surface pipes or tanks where temporary and controllable fluid blockage is required. The frangible rupture disk is made from a pre-stressed glass with controllable rupture properties wherein the strength distribution has a standard deviation less than approximately 5% from the mean strength. The frangible rupture disk has controllable operating pressures and rupture pressures.

  11. Escape dynamics of many hard disks.

    PubMed

    Taniguchi, Tooru; Murata, Hiroki; Sawada, Shin-Ichi

    2014-11-01

    Many-particle effects in escapes of hard disks from a square box via a hole are discussed in a viewpoint of dynamical systems. Starting from N disks in the box at the initial time, we calculate the probability P_{n}(t) for at least n disks to remain inside the box at time t for n=1,2,...,N. At early times, the probabilities P_{n}(t),n=2,3,...,N-1, are described by superpositions of exponential decay functions. On the other hand, after a long time the probability P_{n}(t) shows a power-law decay ∼t^{-2n} for n≠1, in contrast to the fact that it decays with a different power law ∼t^{-n} for cases without any disk-disk collision. Chaotic or nonchaotic properties of the escape systems are discussed by the dynamics of a finite-time largest Lyapunov exponent, whose decay properties are related with those of the probability P_{n}(t). PMID:25493874

  12. Finite Earth

    NASA Astrophysics Data System (ADS)

    2015-10-01

    The world has agreed on 17 Sustainable Development Goals, to be adopted this week. This is great progress towards acknowledging that the planet's finite resources need to be managed carefully in the face of humanity's unlimited aspirations.

  13. I-BIEM calculations of the frequency dispersion and ac current distribution at disk and ring-disk electrodes

    NASA Technical Reports Server (NTRS)

    Cahan, Boris D.

    1991-01-01

    The Iterative Boundary Integral Equation Method (I-BIEM) has been applied to the problem of frequency dispersion at a disk electrode in a finite geometry. The I-BIEM permits the direct evaluation of the AC potential (a complex variable) using complex boundary conditions. The point spacing was made highly nonuniform, to give extremely high resolution in those regions where the variables change most rapidly, i.e., in the vicinity of the edge of the disk. Results are analyzed with respect to IR correction, equipotential surfaces, and reference electrode placement. The current distribution is also examined for a ring-disk configuration, with the ring and the disk at the same AC potential. It is shown that the apparent impedance of the disk is inductive at higher frequencies. The results are compared to analytic calculations from the literature, and usually agree to better than 0.001 percent.

  14. I-BIEM calculations of the frequency dispersion and AC current distribution at disk and ring-disk electrodes

    NASA Technical Reports Server (NTRS)

    Cahan, Boris D.

    1991-01-01

    The Iterative Boundary Integral Equation Method (I-BIEM) has been applied to the problem of frequency dispersion at a disk electrode in a finite geometry. The I-BIEM permits the direct evaluation of the AC potential (a complex variable) using complex boundary conditions. The point spacing was made highly nonuniform, to give extremely high resolution in those regions where the variables change most rapidly, i.e., in the vicinity of the edge of the disk. Results are analyzed with respect to IR correction, equipotential surfaces, and reference electrode placement. The current distribution is also examined for a ring-disk configuration, with the ring and the disk at the same AC potential. It is shown that the apparent impedance of the disk is inductive at higher frequencies. The results are compared to analytic calculations from the literature, and usually agree to better than 0.001 percent.

  15. Radio pulsar disk electrodynamics

    NASA Technical Reports Server (NTRS)

    Michel, F. C.

    1983-01-01

    Macroscopic physics are discussed for the case of a disk close to an isolated, magnetized, rotating neutron star that acts as a Faraday disk dynamo, while the disk acts as both a load and a neutral sheet. This sheet allows the polar cap current to return to the neutron star, splitting a dipolar field into two monopolar halves. The dominant energy loss is from the stellar wind torque, and the next contribution is dissipation in the auroral zones, where the current returns to the star in a 5 cm-thick sheet. The disk itself may be a source of visible radiation comparable to that in pulsed radio frequency emission. As the pulsar ages, the disk expands and narrows into a ring which, it is suggested, may lead to a cessation of pulsed emission at periods of a few sec.

  16. [Skin manifestations of monoclonal gammopathies].

    PubMed

    Hello, M; Barbarot, S; Néel, A; Connault, J; Graveleau, J; Durant, C; Decaux, O; Hamidou, M

    2014-01-01

    Whatever their aetiology, monoclonal gammopathies can be associated to several clinical features. Mechanisms are various and sometimes unknown. Skin is frequently involved and may represent a challenging diagnosis. Indeed, skin manifestations are either the presenting features and isolated, or at the background of a systemic syndrome. Our objective was to review the various skin manifestations that have been associated with monoclonal gammopathies. PMID:24070793

  17. Hyaline fibromatosis syndrome: cutaneous manifestations*

    PubMed Central

    Marques, Silvio Alencar; Stolf, Hamilton Ometto; Polizel, Juliana Ocanha; Munhoz, Tânia; Brandão, Marcela Calixto; Marques, Mariangela Esther Alencar

    2016-01-01

    Hyaline fibromatosis syndrome is the current name for clinical manifestations of diseases previously known as “infantile systemic hyalinosis” and “juvenile hyaline fibromatosis”. The authors report representative clinical cases of each one of the above subtypes with emphasis on cutaneous manifestations and difficulties for early diagnosis in this syndrome, essentially of multidisciplinary approach. PMID:27192526

  18. Dynamics of Circumstellar Disks

    NASA Astrophysics Data System (ADS)

    Nelson, Andrew F.; Benz, Willy; Adams, Fred C.; Arnett, David

    1998-07-01

    We present a series of two-dimensional hydrodynamic simulations of massive disks around protostars. We simulate the same physical problem using both a Piecewise Parabolic Method (PPM) code and a Smoothed Particle Hydrodynamic (SPH) code and analyze their differences. The disks studied here range in mass from 0.05M* to 1.0M* and in initial minimum Toomre Q value from 1.1 to 3.0. We adopt simple power laws for the initial density and temperature in the disk with an isothermal (γ = 1) equation of state. The disks are locally isothermal. We allow the central star to move freely in response to growing perturbations. The simulations using each code are compared to discover differences due to error in the methods used. For this problem, the strengths of the codes overlap only in a limited fashion, but similarities exist in their predictions, including spiral arm pattern speeds and morphological features. Our results represent limiting cases (i.e., systems evolved isothermally) rather than true physical systems. Disks become active from the inner regions outward. From the earliest times, their evolution is a strongly dynamic process rather than a smooth progression toward eventual nonlinear behavior. Processes that occur in both the extreme inner and outer radial regions affect the growth of instabilities over the entire disk. Effects important for the global morphology of the system can originate at quite small distances from the star. We calculate approximate growth rates for the spiral patterns; the one-armed (m = 1) spiral arm is not the fastest growing pattern of most disks. Nonetheless, it plays a significant role because of factors that can excite it more quickly than other patterns. A marked change in the character of spiral structure occurs with varying disk mass. Low-mass disks form filamentary spiral structures with many arms while high-mass disks form grand design spiral structures with few arms. In our SPH simulations, disks with initial minimum Q = 1.5 or

  19. Gastrointestinal Manifestations of Cystic Fibrosis

    PubMed Central

    2016-01-01

    Cystic fibrosis has historically been considered a pulmonary disease, but with the increasing life expectancy of these patients, gastrointestinal manifestations are becoming more important. Furthermore, nutritional status is closely linked to pulmonary function and, thus, overall mortality. This article discusses gastrointestinal manifestations (which involve nutritional, pancreatic, hepatobiliary, and, in particular, gastrointestinal tract issues) of cystic fibrosis as well as management of the disease. In addition, the article discusses studies that have been critical to our understanding of gastrointestinal manifestations of cystic fibrosis. PMID:27330503

  20. Cutaneous Manifestations of Crohn Disease.

    PubMed

    Hagen, Joshua W; Swoger, Jason M; Grandinetti, Lisa M

    2015-07-01

    Awareness of the extraintestinal manifestations of Crohn disease is increasing in dermatology and gastroenterology, with enhanced identification of entities that range from granulomatous diseases recapitulating the underlying inflammatory bowel disease to reactive conditions and associated dermatoses. In this review, the underlying etiopathology of Crohn disease is discussed, and how this mirrors certain skin manifestations that present in a subset of patients is explored. The array of extraintestinal manifestations that do not share a similar pathology, but which are often seen in association with inflammatory bowel disease, is also discussed. Treatment and pathogenetic mechanisms, where available, are discussed. PMID:26143422

  1. Encounters with Protostellar Disks

    NASA Astrophysics Data System (ADS)

    Heller, Clayton H.

    1992-12-01

    A numerical study of encounters between stars with circumstellar disks has bee completed. Cross sections and rates for disk tilt, disk disruption, and binary formation are estimated using a large data base of encounter simulations. The consequences of these results for star-forming regions and our solar system are discussed. A numerical code is developed which is capable of evolving a mixture of stars and gas in three dimensions. The algorithm is based on the method of smoothed-particle hydrodynamics combined with the heirarchical tree method of computing gravitational forces. The code is tested by simulating the collision between two sheets of gas and the radial pulsations of a polytropic gas sphere. A protostellar-disk model is developed based on simple assumptions. Test encounters are performed to determine the sensitivity of measured quantities on algorithm parameters, such as the gravitational tolerance and viscosity. It is shown that the solar system could have had an encounter shortly after its formation of sufficient strength to generate the observed obliquity yet retain enough mass and radial extent to form the planetary system. For the Orion B clusters as a whole, it is estimated that during a one-million-year period of time a few percent of the stars will experience an enoucnter that results in a disk tilt of 7 degrees or greater. For the central regions of NGC 2024 and the Trapezium cluster values of 24% and 39% are obtained, respectively. Encounters between equal-mass stars with periastra of 0.5, 1.0, 1.5, and 2.0 disk radii will retain on average about 15%, 40%, 55%, and 75% of the disk mass, respectively. For encounters that do not penetrate the disk a minimum of 15% of the mass is retained. Even in dense environments the characteristic lifetime of a disk due to disruptive encounters can be many millions of years. On average, an encounter that penetrates the disk will dissipate an amount of orbital energy equal to approximately 50% of the initial

  2. Gas in Protoplanetary Disks

    NASA Technical Reports Server (NTRS)

    Roberge, Aki

    2008-01-01

    Gas makes up the bulk of the mass in a protoplanetary disk, but it is much more difficult to observe than the smaller dust component. The l ifetime of gas in a disk has far-reaching consequences. including lim iting the time available for giant planet formation and controlling t he migration of planetary bodies of all sizes, from Jupiters to meter-sized planetesimals. Here I will discuss what is known about the gas component of protoplanetary disks, highlighting recent results from i nfrared studies with the Spitzer Space Telescope. Exciting upcoming o pportunities for gas studies will also be discussed. In particular, the first large far-IR survey of gas tracers from young disks will be p erformed using the Herschel Space Observatory, as part of the "Gas in Protoplanetary Systems" (GASPS) Open Time Key Project.

  3. Gas in Protoplanetary Disks

    NASA Technical Reports Server (NTRS)

    Roberge, Aki

    2008-01-01

    Gas makes up the bulk of the mass in a protoplanetary disk, but it is much more difficult to observe than the smaller dust component. The lifetime of gas in a disk has far-reaching consequences, including limiting the time available for giant planet formation and controlling the migration of planetary bodies of all sizes, from Jupiters to meter-sized planetesimals. Here I will discuss what is known about the gas component of protoplanetary disks, highlighting recent results from infrared studies with the Spitzer Space Telescope. Exciting upcoming opportunities for gas studies will also be discussed. In particular, the first large far-IR survey of gas tracers from young disks will be performed using the Herschel Space Observatory, as part of the 'Gas in Protoplanetary Systems' (GASPS) Open Time Key Project.

  4. Organizing Your Hard Disk.

    ERIC Educational Resources Information Center

    Stocker, H. Robert; Hilton, Thomas S. E.

    1991-01-01

    Suggests strategies that make hard disk organization easy and efficient, such as making, changing, and removing directories; grouping files by subject; naming files effectively; backing up efficiently; and using PATH. (JOW)

  5. Quantum manifestations of Nekhoroshev stability

    NASA Astrophysics Data System (ADS)

    Fontanari, Daniele; Fassò, Francesco; Sadovskií, Dmitrií A.

    2016-09-01

    We uncover quantum manifestations of classical Nekhoroshev theory of resonant dynamics using a simple quantum system of two coupled angular momenta with conserved equal magnitudes which corresponds to a perturbed classical integrable anisochronous Hamiltonian system.

  6. DIAGNOSING CIRCUMSTELLAR DEBRIS DISKS

    SciTech Connect

    Hahn, Joseph M.

    2010-08-20

    A numerical model of a circumstellar debris disk is developed and applied to observations of the circumstellar dust orbiting {beta} Pictoris. The model accounts for the rates at which dust is produced by collisions among unseen planetesimals, and the rate at which dust grains are destroyed due to collisions. The model also accounts for the effects of radiation pressure, which is the dominant perturbation on the disk's smaller but abundant dust grains. Solving the resulting system of rate equations then provides the dust abundances versus grain size and dust abundances over time. Those solutions also provide the dust grains' collisional lifetime versus grain size, and the debris disk's optical depth and surface brightness versus distance from the star. Comparison to observations then yields estimates of the unseen planetesimal disk's radius, and the rate at which the disk sheds mass due to planetesimal grinding. The model can also be used to measure or else constrain the dust grain's physical and optical properties, such as the dust grains' strength, their light-scattering asymmetry parameter, and the grains' efficiency of light scattering Q{sub s}. The model is then applied to optical observations of the edge-on dust disk orbiting {beta} Pictoris, and good agreement is achieved when the unseen planetesimal disk is broad, with 75 {approx}< r {approx}< 150 AU. If it is assumed that the dust grains are bright like Saturn's icy rings (Q{sub s} = 0.7), then the cross section of dust in the disk is A{sub d} {approx_equal} 2 x 10{sup 20} km{sup 2} and its mass is M{sub d} {approx_equal} 11 lunar masses. In this case, the planetesimal disk's dust-production rate is quite heavy, M-dot {sub d{approx}}9 M {sub +} Myr{sup -1}, implying that there is or was a substantial amount of planetesimal mass there, at least 110 Earth masses. If the dust grains are darker than assumed, then the planetesimal disk's mass-loss rate and its total mass are heavier. In fact, the apparent dearth

  7. Planet Forming Protostellar Disks

    NASA Technical Reports Server (NTRS)

    Lubow, Stephen

    1998-01-01

    The project achieved many of its objectives. The main area of investigation was the interaction of young binary stars with surrounding protostellar disks. A secondary objective was the interaction of young planets with their central stars and surrounding disks. The grant funds were used to support visits by coinvestigators and visitors: Pawel Artymowicz, James Pringle, and Gordon Ogilvie. Funds were also used to support travel to meetings by Lubow and to provide partial salary support.

  8. Protostars and Disks

    NASA Technical Reports Server (NTRS)

    Ho, Paul

    1997-01-01

    The research concentrated on high angular resolution (arc-second scale) studies of molecular cloud cores associated with very young star formation. New ways to study disks and protoplanetary systems were explored. Findings from the areas studied are briefly summarized: (1) molecular clouds; (2) gravitational contraction; (3) jets, winds, and outflows; (4) Circumstellar Disks (5) Extrasolar Planetary Systems. A bibliography of publications and submitted papers produced during the grant period is included.

  9. Oral Manifestations of Secondary Syphilis.

    PubMed

    de Paulo, Luiz Fernando Barbosa; Servato, João Paulo Silva; Oliveira, Maiolino Thomaz Fonseca; Durighetto, Antonio Francisco; Zanetta-Barbosa, Darceny

    2015-06-01

    Known as "the great imitator," secondary syphilis may clinically manifest itself in myriad ways, involving different organs including the oral mucosa, and mimicking, both clinically and histologically, several diseases, thereby making diagnosis a challenge for clinicians. We highlight the clinical aspects of oral manifestation in 7 patients with secondary syphilis. Clinicians should consider secondary syphilis in the differential diagnosis of ulcerative and/or white oral lesions. PMID:25892249

  10. Disk Precession in Pleione

    NASA Astrophysics Data System (ADS)

    Hirata, R.

    2007-03-01

    From the polarimetric observation of Pleione, we found that the intrinsic polarization angle varied from 60° to 130° in 1974-2003. The Hα profile also changed dramatically from the edge-on type (shell-line profile) to the surface-on type (wine-bottle profile). These facts clearly indicate the spatial motion of the disk axis. We interpret these variations in terms of the disk precession, caused by the secondary of this spectroscopic binary with a period of 218d. We performed the χ^2 minimization for the polarization angle, assuming uniform precession with an imposed condition that the shell maximum occurred at edge-on view. The resulting precession angle is 59° with a period of 81 years. Then, we can describe chronologically the spatial motion of disk axis. We also derived the Hα disk radius from the peak separation, assuming the Keplerian disk. The precession of the disk gives natural explanation of the mysterious long-term spectroscopic behaviors of this star.

  11. Young Planetary disks

    NASA Astrophysics Data System (ADS)

    Lecavelier Des Etangs, A.

    2007-07-01

    The present review focuses on UV observations of young planetary disks and consequently mostly on the gaseous content of those disks. Few examples are taken to illustrate the capability of the UV observatories to scrutinize in detail the gas content of low density circumstellar disks if they are seen edge-on or nearly edge-on. For instance, in the case of HD100546, FUSE observations re- vealed signatures of outflow and infall in the disk caused by interaction of the stellar magnetosphere with the circumstellar disk. Observations of numerous absorption lines from H2 around young stars give constrains on the gas temper- ature and density, and physical size of the absorbing layer. In the case of T-Tauri stars and one brown dwarf, emissions from exited H2 have been detected. In the case of Beta Pictoris, the observation of CO in the UV and search for H2 with FUSE demonstrated that the evaporation of frozen bodies like comets must produce the CO seen in the disk. Extensive observations of spectral variability of Beta Pictoris are now interpreted by extrasolar comets evaporating in the vicinity of the central star of this young planetary system.

  12. Neurological manifestations of filarial infections.

    PubMed

    Bhalla, Devender; Dumas, Michel; Preux, Pierre-Marie

    2013-01-01

    Filarial infections cause a huge public health burden wherever they are endemic. These filaria may locate anywhere in the human body. Their manifestations and pathogenic mechanisms, except the most common ones, are rarely investigated systematically. Their neurological manifestations, however, are being increasingly recognized particularly with onchocerciasis or Loa loa infections, Wuchereria bancrofti, or Mansonella perstans. The risk of developing these manifestations may also increase in cases that harbor multiple filariasis or coinfections, for instance as with Plasmodium. The microfilaria of Onchocerca and Loa loa are seen in cerebrospinal fluid. The pathogenesis of neurological manifestations of these infections is complex; however, pathogenic reactions may be caused by mechanical disruption, e.g., degeneration often followed by granulomas, causing fibrosis or mass effects on other tissues, vascular lesions, e.g., vascular block of cerebral vessels, or disordered inflammatory responses resulting in meningitis, encephalitis or localized inflammatory responses. The chances of having neurological manifestations may also depend upon the frequency and"heaviness"of infection over a lifetime. Hence, this type of infection should no longer be considered a disease of the commonly affected areas but one that may produce systemic effects or other manifestations, and these should be considered in populations where they are endemic. PMID:23829914

  13. Herman's Condition and Siegel Disks of Bi-Critical Polynomials

    NASA Astrophysics Data System (ADS)

    Chéritat, Arnaud; Roesch, Pascale

    2016-06-01

    We extend a theorem of Herman from the case of unicritical polynomials to the case of polynomials with two finite critical values. This theorem states that Siegel disks of such polynomials, under a diophantine condition (called Herman's condition) on the rotation number, must have a critical point on their boundaries.

  14. Fast, Capacious Disk Memory Device

    NASA Technical Reports Server (NTRS)

    Muller, Ronald M.

    1990-01-01

    Device for recording digital data on, and playing back data from, memory disks has high recording or playback rate and utilizes available recording area more fully. Two disks, each with own reading/writing head, used to record data at same time. Head on disk A operates on one of tracks numbered from outside in; head on disk B operates on track of same number in sequence from inside out. Underlying concept of device applicable to magnetic or optical disks.

  15. Disk flexibility effects on the rotordynamics of the SSME high pressure turbopumps

    NASA Technical Reports Server (NTRS)

    Flowers, George T.

    1990-01-01

    Rotordynamical analyses are typically performed using rigid disk models. Studies of rotor models in which the effects of disk flexibility were included indicate that it may be an important effect for many systems. This issue is addressed with respect to the Space Shuttle Main Engine high pressure turbopumps. Finite element analyses were performed for a simplified free-free flexible disk rotor models and the modes and frequencies compared to those of a rigid disk model. Equations were developed to account for disk flexibility in rotordynamical analysis. Simulation studies were conducted to assess the influence of disk flexibility on the HPOTP. Some recommendations are given as to the importance of disk flexibility and for how this project should proceed.

  16. Dust in circumstellar disks

    NASA Astrophysics Data System (ADS)

    Rodmann, Jens

    2006-02-01

    This thesis presents observational and theoretical studies of the size and spatial distribution of dust particles in circumstellar disks. Using millimetre interferometric observations of optically thick disks around T Tauri stars, I provide conclusive evidence for the presence of millimetre- to centimetre-sized dust aggregates. These findings demonstrate that dust grain growth to pebble-sized dust particles is completed within less than 1 Myr in the outer disks around low-mass pre-main-sequence stars. The modelling of the infrared spectral energy distributions of several solar-type main-sequence stars and their associated circumstellar debris disks reveals the ubiquity of inner gaps devoid of substantial amounts of dust among Vega-type infrared excess sources. It is argued that the absence of circumstellar material in the inner disks is most likely the result of the gravitational influence of a large planet and/or a lack of dust-producing minor bodies in the dust-free region. Finally, I describe a numerical model to simulate the dynamical evolution of dust particles in debris disks, taking into account the gravitational perturbations by planets, photon radiation pressure, and dissipative drag forces due to the Poynting-Robertson effect and stellar wind. The validity of the code it established by several tests and comparison to semi-analytic approximations. The debris disk model is applied to simulate the main structural features of a ring of circumstellar material around the main-sequence star HD 181327. The best agreement between model and observation is achieved for dust grains a few tens of microns in size locked in the 1:1 resonance with a Jupiter-mass planet (or above) on a circular orbit.

  17. The protean manifestations of pheochromocytoma.

    PubMed

    Manger, W M

    2009-09-01

    The treacherous and deceptive nature of pheochromocytoma makes it crucial to detect and treat it promptly; otherwise it will almost certainly be fatal from cardiovascular complications or metastases. Hypertension occurring in patients with pheochromocytomas is sustained in about 50% and paroxysmal in the remainder; however, many patients remain normotensive. Hypertension attacks may be precipitated by physical activity, postural changes, anxiety, certain foods or wine, some drugs, operative procedures, etc. Cardinal manifestations are paroxysmal hypertension, headache, palpitations +/- tachycardia, inappropriate sweating; anxiety, tremulousness, pallor (rarely flushing), chest and abdominal pains; nausea and vomiting often occur. Hypercatecholaminemia manifestations are more common and pronounced when paroxysmal hypertension occurs, but persons with familial pheochromocytoma may be asymptomatic. Protean manifestations of pheochromocytoma may simulate many conditions, some of which may have elevated plasma and urine catecholamines and their metabolites. Baro-reflex failure, postural tachycardia syndrome, sleep apnea, carcinoid, renal failure, and pseudopheochromocytoma may be diagnostic challenges. The history, physical examination, biochemical testing (after eliminating interfering drugs, when possible) for plasma and urinary metanephrines can usually establish or exclude presence of pheochromocytomas. Occasionally a clonidine suppression test is needed to differentiate neurogenic from pheochromocytic hypertension. Manifestations suggesting hypercatecholaminemia without hypertension are highly atypical of pheochromocytoma. Pheochromocytoma may present as panic attacks, pre-eclampsia, cardiomyopathy, infection with fever and leucocytosis, diabetes, migraine, shock, Cushing's syndrome, multiple organ failure with lactic acidosis, neurological manifestations, transitory electrocardiogram abnormalities, constipation, intestinal obstruction, visual impairment

  18. Determination of stresses in gas-turbine disks subjected to plastic flow and creep

    NASA Technical Reports Server (NTRS)

    Millenson, M B; Manson, S S

    1948-01-01

    A finite-difference method previously presented for computing elastic stresses in rotating disks is extended to include the computation of the disk stresses when plastic flow and creep are considered. A finite-difference method is employed to eliminate numerical integration and to permit nontechnical personnel to make the calculations with a minimum of engineering supervision. Illustrative examples are included to facilitate explanation of the procedure by carrying out the computations on a typical gas-turbine disk through a complete running cycle. The results of the numerical examples presented indicate that plastic flow markedly alters the elastic-stress distribution.

  19. Photoprocesses in protoplanetary disks.

    PubMed

    van Dishoeck, Ewine F; Jonkheid, Bastiaan; van Hemert, Marc C

    2006-01-01

    Circumstellar disks are exposed to intense ultraviolet (UV) radiation from the young star. In the inner disks, the UV radiation can be enhanced by more than seven orders of magnitude compared with the average interstellar radiation field, resulting in a physical and chemical structure that resembles that of a dense photon-dominated region (PDR). This intense UV field affects the chemistry, the vertical structure of the disk, and the gas temperature, especially in the surface layers. The parameters which make disks different from more traditional PDRs are discussed, including the shape of the UV radiation field, grain growth, the absence of PAHs, the gas/dust ratio and the presence of inner holes. Illustrative infrared spectra from the Spitzer Space Telescope are shown. New photodissociation cross sections for selected species, including simple ions, are presented. Also, a summary of cross sections at the Lyman alpha 1216 A line, known to be strong for some T Tauri stars, is made. Photodissociation and ionization rates are computed for different radiation fields with color temperatures ranging from 30000 to 4000 K and grain sizes up to a few microm. The importance of a proper treatment of the photoprocesses is illustrated for the transitional disk toward HD 141569A which includes grain growth. PMID:17191450

  20. PLANETESIMAL DISK MICROLENSING

    SciTech Connect

    Heng, Kevin; Keeton, Charles R. E-mail: keeton@physics.rutgers.ed

    2009-12-10

    Motivated by debris disk studies, we investigate the gravitational microlensing of background starlight by a planetesimal disk around a foreground star. We use dynamical survival models to construct a plausible example of a planetesimal disk and study its microlensing properties using established ideas of microlensing by small bodies. When a solar-type source star passes behind a planetesimal disk, the microlensing light curve may exhibit short-term, low-amplitude residuals caused by planetesimals several orders of magnitude below Earth mass. The minimum planetesimal mass probed depends on the photometric sensitivity and the size of the source star, and is lower when the planetesimal lens is located closer to us. Planetesimal lenses may be found more nearby than stellar lenses because the steepness of the planetesimal mass distribution changes how the microlensing signal depends on the lens/source distance ratio. Microlensing searches for planetesimals require essentially continuous monitoring programs that are already feasible and can potentially set constraints on models of debris disks, the progeny of the supposed extrasolar analogues of Kuiper Belts.

  1. The Chemistry of Nearby Disks

    NASA Astrophysics Data System (ADS)

    Öberg, Karin I.

    2016-01-01

    The gas and dust rich disks around young stars are the formation sites of planets. Observations of molecular trace species have great potential as probes of the disk structures and volatile compositions that together regulate planet formation. The disk around young star TW Hya has become a template for disk molecular studies due to a combination of proximity, a simple face-on geometry and richness in volatiles. It is unclear, however, how typical the chemistry of the TW disk is. In this proceeding, we review lessons learnt from exploring the TW Hya disk chemistry, focusing on the CO snowline, and on deuterium fractionation chemistry. We compare these results with new ALMA observations toward more distant, younger disks. We find that while all disks have some chemical structures in common, there are also substantial differences between the disks, which may be due to different initial conditions, structural or chemical evolutionary stages, or a combination of all three.

  2. [Cardiovascular manifestations of human toxocariasis].

    PubMed

    Bolívar-Mejía, Adrián; Rodríguez-Morales, Alfonso J; Paniz-Mondolfi, Alberto E; Delgado, Olinda

    2013-01-01

    Toxocariasis is a parasitic infection produced by helminths that cannot reach their adult stage in humans. For their etiological species (Toxocara canis and Toxocara cati), man is a paratenic host. Infection by such helminths can produce a variety of clinical manifestations, such as: visceral larvae migrans syndrome, ocular larvae migrans syndrome and covert toxocariasis. In the visceral larvae migrans syndrome, the organs that are mainly involved include liver, lungs, skin, nervous system, muscles, kidneys and the heart. Regarding the latter, the importance of cardiovascular manifestations in toxocariasis, as well as its clinical relevance, has increasingly begun to be recognized. The current article is based on a systematic information search, focused mainly on the clinical and pathological aspects of cardiovascular manifestations in toxocariasis, including its pathophysiology, laboratory findings, diagnosis and therapeutical options, with the objective of highlighting its importance as a zoonosis and its relevance to the fields of cardiovascular medicine in adults and children. PMID:23462238

  3. Aquagenic urticaria with extracutaneous manifestations.

    PubMed

    Baptist, Alan P; Baldwin, James L

    2005-01-01

    Aquagenic urticaria (AU) is a rare form of physical urticaria in which contact with water evokes hives. Extracutaneous manifestations of AU have been described but have not been controlled successfully to date. Selective serotonin reuptake inhibitors (SSRIs) have not been used previously in the treatment of AU. The aim of this study was to describe a case of AU with extracutaneous manifestations, to describe a novel treatment approach, and to review the literature on AU. Our patient presented with urticarial lesions and migraine-like headaches after contact with any type of water. A variety of prophylactic medications including antihistamines, anticholinergics, and SSRIs, were used and, ultimately, were successful in controlling the patient's symptoms. AU is a rare condition that can have extracutaneous manifestations. Multiple classes of medications, including SSRIs, may be necessary in the treatment and prophylaxis of such patients. Additional research is needed into the pathogenesis of AU. PMID:16119038

  4. Neurocutaneous Manifestations of Genetic Mosaicism.

    PubMed

    van Steensel, Maurice A M

    2015-09-01

    Genetic mosaicism is defined as the presence of two or more genetically distinct cell populations in a single individual. Ever more disorders are found to be manifestations of mosaicism and together constitute a significant proportion of the morbidity confronting pediatric specialists. An emerging category is that of overgrowth syndromes with skin manifestations and neurological or developmental abnormalities, such as the well-known Proteus syndrome. In recent years, we have seen dramatic advances in our understanding of these disorders and we now know the genetic basis of many of them. This has profound consequences for diagnosis, counselling, and even treatment, with therapies targeted to specific pathways becoming available for clinical use. Recognizing such overgrowth syndromes, therefore, is more important than ever. Fortunately, their skin manifestations can provide important diagnostic clues when evaluated in the entire phenotypic context. In this review, I provide an overview of the most frequently seen mosaic neurocutaneous phenotypes and discuss their molecular basis. PMID:27617125

  5. How The Inner Disk Communicates to the Outer Disk

    NASA Astrophysics Data System (ADS)

    Goto, Miwa

    2009-08-01

    We investigated how evolution in the outer disk has an influence on the inner disk of a protoplanetary disk system. Thanks to two-layer models that give the theoretical platform of disk geometry, we now have a good handle on how dust evolves in outer protoplanetary disks (>10 AU). It has long been thought that the outer and inner disks dissipate on roughly the same time scale as sub-mm observations of nearby T Tauri systems has suggested. However, new high spatial resolution observations point toward the dissipation of an inner disk as not being a simple extension of the outer disk. We performed preliminary tests of the differential disk evolution in gas and dust in the inner disks of Herbig Ae/Be stars using the CO vibrational band as the gas probe. The line luminosity of CO v = 1-0 P(30) has a reasonable correlation with the near-infrared excess over the stellar photosphere. It guarantees that the CO vibration band is a secure probe of the inner disk, as is expected from its high critical density, high excitation temperature, and kinematics. On the other hand, the line luminosity of P(30) does not show a clear trend either with far-infrared color, near-infrared/far-infrared-color, or the type of the spectral energy distribution (SED) (I/II). The inner disks (<1 AU) of Herbig Ae/Be stars of our sample are influenced little by the geometry of the outer disks.

  6. Chemistry in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Semenov, D. A.

    2012-01-01

    In this lecture I discuss recent progress in the understanding of the chemical evolution of protoplanetary disks that resemble our Solar system during the first ten million years. At the verge of planet formation, strong variations of temperature, density, and radiation intensities in these disks lead to a layered chemical structure. In hot, dilute and heavily irradiated atmosphere only simple radicals, atoms, and atomic ions can survive, formed and destroyed by gas-phase processes. Beneath the atmosphere a partly UV-shielded, warm molecular layer is located, where high-energy radiation drives rich chemistry, both in the gas phase and on dust surfaces. In a cold, dense, dark disk midplane many molecules are frozen out, forming thick icy mantles where surface chemistry is active and where complex (organic) species are synthesized.

  7. Packings of soft disks

    NASA Astrophysics Data System (ADS)

    Ziherl, Primoz; Vidmar, Marija

    2011-03-01

    We explore the stability of 2D ordered structures formed by soft disks treated as isotropic solid bodies. Using a variational model, we compute the equilibrium shapes and the elastic energy of disks in regular columnar, honeycomb, square, and hexagonal lattice. The results reproduce the Hertzian interaction in the regime of small deformations. The phase diagram of elastic disks is characterized by broad regions of phase coexistence; its main feature is that the coordination number of the stable phases decreases with density. These results may provide an insight into structure of the non-close-packed lattices observed in certain nanocolloidal systems. This work was supported by Slovenian Research Agency (grant No. P1-0055) and by EU through ITN COMPLOIDS (grant FP7-People-ITN-2008 No. 234810).

  8. Premixed direct injection disk

    SciTech Connect

    York, William David; Ziminsky, Willy Steve; Johnson, Thomas Edward; Lacy, Benjamin; Zuo, Baifang; Uhm, Jong Ho

    2013-04-23

    A fuel/air mixing disk for use in a fuel/air mixing combustor assembly is provided. The disk includes a first face, a second face, and at least one fuel plenum disposed therebetween. A plurality of fuel/air mixing tubes extend through the pre-mixing disk, each mixing tube including an outer tube wall extending axially along a tube axis and in fluid communication with the at least one fuel plenum. At least a portion of the plurality of fuel/air mixing tubes further includes at least one fuel injection hole have a fuel injection hole diameter extending through said outer tube wall, the fuel injection hole having an injection angle relative to the tube axis. The invention provides good fuel air mixing with low combustion generated NOx and low flow pressure loss translating to a high gas turbine efficiency, that is durable, and resistant to flame holding and flash back.

  9. Supersized Disk (Artist's Concept)

    NASA Technical Reports Server (NTRS)

    2006-01-01

    [figure removed for brevity, see original site] Annotated ImageData Graph

    This illustration compares the size of a gargantuan star and its surrounding dusty disk (top) to that of our solar system. Monstrous disks like this one were discovered around two 'hypergiant' stars by NASA's Spitzer Space Telescope. Astronomers believe these disks might contain the early 'seeds' of planets, or possibly leftover debris from planets that already formed.

    The hypergiant stars, called R 66 and R 126, are located about 170,000 light-years away in our Milky Way's nearest neighbor galaxy, the Large Magellanic Cloud. The stars are about 100 times wider than the sun, or big enough to encompass an orbit equivalent to Earth's. The plump stars are heavy, at 30 and 70 times the mass of the sun, respectively. They are the most massive stars known to sport disks.

    The disks themselves are also bloated, with masses equal to several Jupiters. The disks begin at a distance approximately 120 times greater than that between Earth and the sun, or 120 astronomical units, and terminate at a distance of about 2,500 astronomical units.

    Hypergiant stars are the puffed-up, aging descendants of the most massive class of stars, called 'O' stars. The stars are so massive that their cores ultimately collapse under their own weight, triggering incredible explosions called supernovae. If any planets circled near the stars during one of these blasts, they would most likely be destroyed.

    The orbital distances in this picture are plotted on a logarithmic scale. This means that a given distance shown here represents proportionally larger actual distances as you move to the right. The sun and planets in our solar system have been scaled up in size for better viewing. Little Dust Grains in Giant Stellar Disks The graph above of data from NASA's Spitzer Space Telescope shows the composition of a monstrous disk of what may be planet-forming dust circling the colossal 'hypergiant' star

  10. Neurologic Manifestations of Blood Dyscrasias.

    PubMed

    Couriel, Daniel R; Ricker, Holly; Steinbach, Mary; Lee, Catherine J

    2016-08-01

    Neurologic manifestations are common in blood diseases, and they can be caused by the hematologic disorder or its treatment. This article discusses hematologic diseases in adult patients, and categorizes them into benign and malignant conditions. The more common benign hematologic diseases associated with neurologic manifestations include anemias, particularly caused by B12 deficiency and sickle cell disease, and a variety of disorders of hemostasis causing bleeding or thrombosis, including thrombotic microangiopathy. Malignant conditions like multiple myeloma, leukemias, and lymphomas can have neurologic complications resulting from direct involvement, or caused by the different therapies to treat these cancers. PMID:27443994

  11. Atypical neurological manifestations of malaria

    PubMed Central

    Singla, Neeraj; Gupta, Monica; Singh, Ram; Kumar, Ashwani

    2014-01-01

    Malaria is known as a great mimic. It can manifest subtly or abruptly, typically or atypically. This aspect of the disease can frequently mislead physicians. We present two patients of malaria with atypical neurological manifestations. The first patient of Plasmodium falciparum malaria presented with fever and altered sensorium; MRI of the brain suggested cerebral venous thrombosis. The second patient of Plasmodium vivax presented with fever, double vision and right eye lateral rectus palsy due to unilateral sixth cranial nerve involvement. Both patients were managed with antimalarials and supportive medical management, and had uneventful recoveries. PMID:25150266

  12. Cutaneous manifestations in celiac disease.

    PubMed

    Abenavoli, L; Proietti, I; Leggio, L; Ferrulli, A; Vonghia, L; Capizzi, R; Rotoli, M; Amerio, P L; Gasbarrini, G; Addolorato, G

    2006-02-14

    Celiac disease (CD) is an autoimmune gluten-dependent enteropathy characterized by atrophy of intestinal villi that improves after gluten-free diet (GFD). CD is often associated with extra-intestinal manifestations; among them, several skin diseases are described in CD patients. The present review reports all CD-associated skin manifestations described in the literature and tries to analyze the possible mechanisms involved in this association. The opportunity to evaluate the possible presence of CD in patients affected by skin disorders is discussed. PMID:16521210

  13. Observations of Protostellar Disks

    NASA Astrophysics Data System (ADS)

    Ménard, F.

    2004-12-01

    Accretion disks are pivotal elements in the formation and early evolution of solar-like stars. On top of supplying the raw material, their internal conditions also regulate the formation of planets. Their study therefore holds the key to solve the mystery of the formation of our Solar System. This chapter focuses on observational studies of circumstellar disks associated with pre-main sequence solar-like stars. The direct measurement of disk parameters poses an obvious challenge: at the distance of typical star forming regions (e.g., ˜140pc for Taurus), a planetary system like ours (with diameter ≃ 50AU out to Pluto, but excluding the Kuiper belt) subtends only 0.35". Yet its surface brightness is low in comparison to the bright central star and high angular and high contrast imaging techniques are required if one hopes to resolve and measure these protoplanetary disks. Fortunately, capable instruments providing 0.1" resolution or better and high contrast have been available for just about 10 years now. They are covering a large part of the electromagnetic spectrum, from the UV/Optical with HST and the near-infrared from ground-based adaptive optics systems, to the millimetric range with long-baseline radio interferometers. It is therefore not surprising that our knowledge of the structure of the disks surrounding low-mass stars has made a gigantic leap forward in the last decade. In the following pages I will attempt to give an overview of the structural and physical parameters of protoplanetary disks that can be estimated today from direct observations.

  14. The structure of protostellar accretion disks and the origin of bipolar flows

    NASA Technical Reports Server (NTRS)

    Wardle, Mark; Koenigl, Arieh

    1993-01-01

    Equations are obtained which govern the disk-wind structure and identify the physical parameters relevant to circumstellar disks. The system of equations is analyzed in the thin-disk approximation, and it is shown that the system can be consistently reduced to a set of ordinary differential equations in z. Representative solutions are presented, and it is shown that the apparent paradox discussed by Shu (1991) is resolved when the finite thickness of the disk is taken into account. Implications of the results for the origin of bipolar flows in young stellar objects and possible application to active galactic nuclei are discussed.

  15. MPP disk subsystem

    NASA Technical Reports Server (NTRS)

    Hudgins, W. A.

    1984-01-01

    A disk subsystem for the Massively Parallel processor (MPP) is designed to the block diagram level. The subsystem is capable of storing 4,992 megabytes of data, expandable to 39,936 megabytes. The subsystem is capable of transferring data to the MPP Staging Memory at a rate of 25 megabytes/second, expandable to 100 megabytes/second. A lower cost disk subsystem is also presented. This alternate subsystem is capable of storing 3,744 megabytes with a transfer rate of 10.6 megabyte/second.

  16. Psychiatric manifestations in cerebrotendinous xanthomatosis

    PubMed Central

    Fraidakis, M J

    2013-01-01

    Cerebrotendinous xanthomatosis (CTX) is a rare and severe, but treatable, inborn disorder of bile acid biosynthesis and sterol storage with autosomal recessive inheritance and variable clinical presentation. CTX treatment consists of chenodeoxycholic acid and must be started as early as possible to prevent permanent disability. Psychiatric manifestations are rare and non-specific, and often lead to significant diagnostic and treatment delay. Therefore, better recognition of the gamut of psychiatric manifestations in CTX can diminish the risk of misdiagnosis and irreversible neurological deterioration. We hereby describe the psychiatric features in CTX. A complete review of all published cases of CTX in the medical literature was undertaken and the case reports with psychiatric presentation were collected and analyzed. We also describe the psychiatric features in relation to the neurological semeiology in six patients with CTX diagnosed at the La Salpêtrière Hospital. We conclude that psychiatric manifestations in CTX follow a bimodal/bitemporal pattern, appearing early in the disease course in the form of a behavioral/personality disorder associated with learning difficulties or mental retardation, or manifesting in advanced disease in the setting of dementia as rich neuropsychiatric syndromes, such as frontal, orbitofrontal or frontotemporal syndromes of cortico-subcortical dementia encompassing behavioral/personality disturbance, affective/mood disorders or psychotic disorders. Behavioral/personality disturbance in childhood or adolescence, especially when accompanied by learning difficulties, should therefore lead to further investigation to exclude CTX, as early diagnosis and treatment is critical for prognosis. PMID:24002088

  17. [Clinical manifestations of cerebellar ataxias].

    PubMed

    Abdulkerimov, Kh T

    2003-01-01

    The analysis of clinical manifestations and focal symptoms in 18 patients with cerebellar ataxia (CA) has shown that these markers are not sufficient for making an accurate diagnosis in all CA cases. It is recommended to verify an ataxia form with objective methods, computed stabilography, in particular. PMID:12958853

  18. Clinical manifestations of cerebellar disease.

    PubMed

    Javalkar, Vijayakumar; Khan, Misbba; Davis, Debra E

    2014-11-01

    Clinical manifestations of cerebellar disease include ataxia and tremor, as well as nystagmus, dysarthria, and cognitive dysfunction. Recognition of the cerebellar pattern of disease can aid in the prompt and correct diagnosis and lead to appropriate treatment and rehabilitation to minimize disability. PMID:25439285

  19. Nonmotor manifestations of Parkinson's disease.

    PubMed

    Simuni, Tanya; Sethi, Kapil

    2008-12-01

    Parkinson's disease (PD) is the second most common neurodegenerative disease after Alzheimer's disease. Traditionally, attention has focused on the motor symptomatology of PD, but it is now appreciated that the nonmotor symptoms affecting neuropsychiatric, sleep, autonomic, and sensory domains occur in up to 88% of PD patients and can be an important source of disability. Nonmotor manifestations of PD play a significant role in the impairment of disease-related quality of life. The cause of nonmotor manifestations of PD is multifactorial, but to a large extent, these manifestations are related to the nature of the neurodegenerative process and the widespread nondopaminergic neuropathological changes associated with the disease. Recognition of nonmotor disability is essential not only for ascertaining the functional status of patients but also for better appreciating the nature of the neurodegenerative process in PD. In addition, a number of nonmotor manifestations can precede the onset of motor symptoms in PD and can be used as screening tools allowing for early disease identification and for trials of possible disease-modifying interventions. This article reviews depression, sleep, and autonomic dysfunction in PD. PMID:19127582

  20. Esophageal Manifestations of Multisystem Diseases

    PubMed Central

    Mapp, Esmond

    1980-01-01

    The esophagus may be involved directly or indirectly by numerous disease conditions. On occasion, the esophageal process may be the key to the diagnosis. In some situations, the esophageal manifestation of a disease may be more immediately life-threatening than the primary process. ImagesFigure 1Figure 2Figure 3Figure 4Figure 5Figure 6 PMID:7310903

  1. GIANT PLANET FORMATION BY DISK INSTABILITY IN LOW MASS DISKS?

    SciTech Connect

    Boss, Alan P.

    2010-12-20

    Forming giant planets by disk instability requires a gaseous disk that is massive enough to become gravitationally unstable and able to cool fast enough for self-gravitating clumps to form and survive. Models with simplified disk cooling have shown the critical importance of the ratio of the cooling to the orbital timescales. Uncertainties about the proper value of this ratio can be sidestepped by including radiative transfer. Three-dimensional radiative hydrodynamics models of a disk with a mass of 0.043 M{sub sun} from 4 to 20 AU in orbit around a 1 M{sub sun} protostar show that disk instabilities are considerably less successful in producing self-gravitating clumps than in a disk with twice this mass. The results are sensitive to the assumed initial outer disk (T{sub o}) temperatures. Models with T{sub o} = 20 K are able to form a single self-gravitating clump, whereas models with T{sub o} = 25 K form clumps that are not quite self-gravitating. These models imply that disk instability requires a disk with a mass of at least {approx}0.043 M{sub sun} inside 20 AU in order to form giant planets around solar-mass protostars with realistic disk cooling rates and outer-disk temperatures. Lower mass disks around solar-mass protostars must rely upon core accretion to form inner giant planets.

  2. Plasmofluidic Disk Resonators

    PubMed Central

    Kwon, Min-Suk; Ku, Bonwoo; Kim, Yonghan

    2016-01-01

    Waveguide-coupled silicon ring or disk resonators have been used for optical signal processing and sensing. Large-scale integration of optical devices demands continuous reduction in their footprints, and ultimately they need to be replaced by silicon-based plasmonic resonators. However, few waveguide-coupled silicon-based plasmonic resonators have been realized until now. Moreover, fluid cannot interact effectively with them since their resonance modes are strongly confined in solid regions. To solve this problem, this paper reports realized plasmofluidic disk resonators (PDRs). The PDR consists of a submicrometer radius silicon disk and metal laterally surrounding the disk with a 30-nm-wide channel in between. The channel is filled with fluid, and the resonance mode of the PDR is strongly confined in the fluid. The PDR coupled to a metal-insulator-silicon-insulator-metal waveguide is implemented by using standard complementary metal oxide semiconductor technology. If the refractive index of the fluid increases by 0.141, the transmission spectrum of the waveguide coupled to the PDR of radius 0.9 μm red-shifts by 30 nm. The PDR can be used as a refractive index sensor requiring a very small amount of analyte. Plus, the PDR filled with liquid crystal may be an ultracompact intensity modulator which is effectively controlled by small driving voltage. PMID:26979929

  3. Accretion disk coronae

    NASA Technical Reports Server (NTRS)

    White, N. E.; Holt, S. S.

    1981-01-01

    Recent observations of partial X-ray eclipses from 4U1822-37 have shown that the central X-ray source in this system is diffused by a large Compton-thick accretion disk corona (ADC). Another binary, 4U2129-47, also displays a partial eclipse and contains an ADC. The possible origin of an ADC is discussed and a simple hydrostatic evaporated ADC model is developed which, when applied to 4U1822-37, 4U2129+47 and Cyg X-3, can explain their temporal and spectral properties. The quasi-sinusoidal modulation of all three sources can be reconciled with the partial occultation of the ADC by a bulge at the edge of the accretion disk which is caused by the inflowing material. The height of this bulge is an order of magnitude larger than the hydrostatic disk height and is the result of turbulence in the outer region of the disk. The spectral properties of all three sources can be understood in terms of Compton scattering of the original source spectrum by the ADC. Spectral variations with epoch in Cyg X-3 are probably caused by changes in the optical depth of the corona. A consequence of our model is that any accreting neutron star X-ray source in a semi-detached binary system which is close to its Eddington limit most likely contains an optically thick ADC.

  4. Solar disk sextant

    NASA Technical Reports Server (NTRS)

    Sofia, S.; Chiu, H.-Y.; Maier, E.; Schatten, K. H.; Minott, P.; Endal, A. S.

    1984-01-01

    This paper presents the conceptual design of an instrument, called the solar disk sextant, to be used in space to measure the shape and the size of the sun and their variations. The instrumental parameters required to produce sufficient sensitivity to address the problems of solar oblateness, solar pulsations, and global size changes of climatic importance are given.

  5. Plasmofluidic Disk Resonators

    NASA Astrophysics Data System (ADS)

    Kwon, Min-Suk; Ku, Bonwoo; Kim, Yonghan

    2016-03-01

    Waveguide-coupled silicon ring or disk resonators have been used for optical signal processing and sensing. Large-scale integration of optical devices demands continuous reduction in their footprints, and ultimately they need to be replaced by silicon-based plasmonic resonators. However, few waveguide-coupled silicon-based plasmonic resonators have been realized until now. Moreover, fluid cannot interact effectively with them since their resonance modes are strongly confined in solid regions. To solve this problem, this paper reports realized plasmofluidic disk resonators (PDRs). The PDR consists of a submicrometer radius silicon disk and metal laterally surrounding the disk with a 30-nm-wide channel in between. The channel is filled with fluid, and the resonance mode of the PDR is strongly confined in the fluid. The PDR coupled to a metal-insulator-silicon-insulator-metal waveguide is implemented by using standard complementary metal oxide semiconductor technology. If the refractive index of the fluid increases by 0.141, the transmission spectrum of the waveguide coupled to the PDR of radius 0.9 μm red-shifts by 30 nm. The PDR can be used as a refractive index sensor requiring a very small amount of analyte. Plus, the PDR filled with liquid crystal may be an ultracompact intensity modulator which is effectively controlled by small driving voltage.

  6. Herniated disk repair (image)

    MedlinePlus

    ... one of the most common causes of lower back pain. The mainstay of treatment for herniated disks is an initial period of rest with pain and anti-inflammatory medications followed by physical therapy. If pain and symptoms persist, surgery to remove ...

  7. 40 CFR 262.21 - Manifest tracking numbers, manifest printing, and obtaining manifests.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... instructions in the appendix to 40 CFR part 262 must appear legibly on the back of the copies of the manifest... AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The...): “Designated facility to destination State (if required)”. (ii) Page 2: “Designated facility to generator...

  8. 40 CFR 262.21 - Manifest tracking numbers, manifest printing, and obtaining manifests.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... instructions in the appendix to 40 CFR part 262 must appear legibly on the back of the copies of the manifest... AGENCY (CONTINUED) SOLID WASTES (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The...): “Designated facility to destination State (if required)”. (ii) Page 2: “Designated facility to generator...

  9. Circumstellar disks of the most vigorously accreting young stars.

    PubMed

    Liu, Hauyu Baobab; Takami, Michihiro; Kudo, Tomoyuki; Hashimoto, Jun; Dong, Ruobing; Vorobyov, Eduard I; Pyo, Tae-Soo; Fukagawa, Misato; Tamura, Motohide; Henning, Thomas; Dunham, Michael M; Karr, Jennifer L; Kusakabe, Nobuhiko; Tsuribe, Toru

    2016-02-01

    Stars may not accumulate their mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. These events can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Our high-resolution near-infrared imaging has verified the presence of the key associated features, large-scale arms and arcs surrounding four young stellar objects undergoing luminous outbursts. Our hydrodynamics simulations and radiative transfer models show that these observed structures can indeed be explained by strong gravitational instabilities occurring at the beginning of the disk formation phase. The effect of those tempestuous episodes of disk evolution on star and planet formation remains to be understood. PMID:26989772

  10. The underexpanded jet Mach disk and its associated shear layer

    NASA Astrophysics Data System (ADS)

    Edgington-Mitchell, Daniel; Honnery, Damon R.; Soria, Julio

    2014-09-01

    High resolution planar particle image velocimetry is used to measure turbulent quantities in the region downstream of the Mach disk in an axisymmetric underexpanded jet issuing from a convergent nozzle. The internal annular shear layer generated by the slip line emanating from the triple point is shown to persist across multiple shock cells downstream. A triple decomposition based on Proper Orthogonal Decomposition shows that the external helical structure associated with the screech tone generated by the jet exerts a strong influence on velocity fluctuations in the initial region of the annular shear layer. This influence manifests as the external vortices producing oscillatory motion of the Mach disk, and thus a forcing of the internal annular shear layer. The internal shear layer is characterized by a number of azimuthal modes of varying wavenumber and type, including both helical and axisymmetric modes. Finally, the possibility of a previously hypothesized recirculation region behind the Mach disk is investigated, with no evidence found to support its existence.

  11. Circumstellar disks of the most vigorously accreting young stars

    PubMed Central

    Liu, Hauyu Baobab; Takami, Michihiro; Kudo, Tomoyuki; Hashimoto, Jun; Dong, Ruobing; Vorobyov, Eduard I.; Pyo, Tae-Soo; Fukagawa, Misato; Tamura, Motohide; Henning, Thomas; Dunham, Michael M.; Karr, Jennifer L.; Kusakabe, Nobuhiko; Tsuribe, Toru

    2016-01-01

    Stars may not accumulate their mass steadily, as was previously thought, but in a series of violent events manifesting themselves as sharp stellar brightening. These events can be caused by fragmentation due to gravitational instabilities in massive gaseous disks surrounding young stars, followed by migration of dense gaseous clumps onto the star. Our high-resolution near-infrared imaging has verified the presence of the key associated features, large-scale arms and arcs surrounding four young stellar objects undergoing luminous outbursts. Our hydrodynamics simulations and radiative transfer models show that these observed structures can indeed be explained by strong gravitational instabilities occurring at the beginning of the disk formation phase. The effect of those tempestuous episodes of disk evolution on star and planet formation remains to be understood. PMID:26989772

  12. Evolution of Accretion Disks in Tidal Disruption Events

    NASA Astrophysics Data System (ADS)

    Shen, Rong-Feng; Matzner, Christopher D.

    2014-04-01

    During a stellar tidal disruption event (TDE), an accretion disk forms as stellar debris returns to the disruption site and circularizes. Rather than being confined within the circularizing radius, the disk can spread to larger radii to conserve angular momentum. A spreading disk is a source of matter for re-accretion at rates that may exceed the later stellar fallback rate, although a disk wind can suppress its contribution to the central black hole accretion rate. A spreading disk is detectible through a break in the central accretion rate history or, at longer wavelengths, by its own emission. We model the evolution of TDE disk size and accretion rate by accounting for the time-dependent fallback rate, for the influence of wind losses in the early advective stage, and for the possibility of thermal instability for accretion rates intermediate between the advection-dominated and gas-pressure-dominated states. The model provides a dynamic basis for modeling TDE light curves. All or part of a young TDE disk will precess as a solid body because of the Lense-Thirring effect, and precession may manifest itself as a quasi-periodic modulation of the light curve. The precession period increases with time. Applying our results to the jetted TDE candidate Swift J1644+57, whose X-ray light curve shows numerous quasi-periodic dips, we argue that the data best fit a scenario in which a main-sequence star was fully disrupted by an intermediate mass black hole on an orbit significantly inclined from the black hole equator, with the apparent jet shutoff at t = 500 days corresponding to a disk transition from the advective state to the gas-pressure-dominated state.

  13. Evolution of accretion disks in tidal disruption events

    SciTech Connect

    Shen, Rong-Feng; Matzner, Christopher D. E-mail: matzner@astro.utoronto.ca

    2014-04-01

    During a stellar tidal disruption event (TDE), an accretion disk forms as stellar debris returns to the disruption site and circularizes. Rather than being confined within the circularizing radius, the disk can spread to larger radii to conserve angular momentum. A spreading disk is a source of matter for re-accretion at rates that may exceed the later stellar fallback rate, although a disk wind can suppress its contribution to the central black hole accretion rate. A spreading disk is detectible through a break in the central accretion rate history or, at longer wavelengths, by its own emission. We model the evolution of TDE disk size and accretion rate by accounting for the time-dependent fallback rate, for the influence of wind losses in the early advective stage, and for the possibility of thermal instability for accretion rates intermediate between the advection-dominated and gas-pressure-dominated states. The model provides a dynamic basis for modeling TDE light curves. All or part of a young TDE disk will precess as a solid body because of the Lense-Thirring effect, and precession may manifest itself as a quasi-periodic modulation of the light curve. The precession period increases with time. Applying our results to the jetted TDE candidate Swift J1644+57, whose X-ray light curve shows numerous quasi-periodic dips, we argue that the data best fit a scenario in which a main-sequence star was fully disrupted by an intermediate mass black hole on an orbit significantly inclined from the black hole equator, with the apparent jet shutoff at t = 500 days corresponding to a disk transition from the advective state to the gas-pressure-dominated state.

  14. CO GAS INSIDE THE PROTOPLANETARY DISK CAVITY IN HD 142527: DISK STRUCTURE FROM ALMA

    SciTech Connect

    Perez, S.; Casassus, S.; Van der Plas, G.; Christiaens, V.; Ménard, F.; Roman, P.; Cieza, L.; Hales, A. S.; Pinte, C.

    2015-01-10

    Inner cavities and annular gaps in circumstellar disks are possible signposts of giant planet formation. The young star HD 142527 hosts a massive protoplanetary disk with a large cavity that extends up to 140 AU from the central star, as seen in continuum images at infrared and millimeter wavelengths. Estimates of the survival of gas inside disk cavities are needed to discriminate between clearing scenarios. We present a spatially and spectrally resolved carbon monoxide isotopologue observations of the gas-rich disk HD 142527, in the J = 2-1 line of {sup 12}CO, {sup 13}CO, and C{sup 18}O obtained with the Atacama Large Millimeter/submillimeter Array (ALMA). We detect emission coming from inside the dust-depleted cavity in all three isotopologues. Based on our analysis of the gas in the dust cavity, the {sup 12}CO emission is optically thick, while {sup 13}CO and C{sup 18}O emissions are both optically thin. The total mass of residual gas inside the cavity is ∼1.5-2 M {sub Jup}. We model the gas with an axisymmetric disk model. Our best-fit model shows that the cavity radius is much smaller in CO than it is in millimeter continuum and scattered light observations, with a gas cavity that does not extend beyond 105 AU (at 3σ). The gap wall at its outer edge is diffuse and smooth in the gas distribution, while in dust continuum it is manifestly sharper. The inclination angle, as estimated from the high velocity channel maps, is 28 ± 0.5 deg, higher than in previous estimates, assuming a fix central star mass of 2.2 M {sub ☉}.

  15. The Evolution of Inner Disk Gas in Transition Disks

    NASA Astrophysics Data System (ADS)

    Hoadley, K.; France, K.; Alexander, R. D.; McJunkin, M.; Schneider, P. C.

    2015-10-01

    Investigating the molecular gas in the inner regions of protoplanetary disks (PPDs) provides insight into how the molecular disk environment changes during the transition from primordial to debris disk systems. We conduct a small survey of molecular hydrogen (H2) fluorescent emission, using 14 well-studied Classical T Tauri stars at two distinct dust disk evolutionary stages, to explore how the structure of the inner molecular disk changes as the optically thick warm dust dissipates. We simulate the observed Hi-Lyman α-pumped H2 disk fluorescence by creating a 2D radiative transfer model that describes the radial distributions of H2 emission in the disk atmosphere and compare these to observations from the Hubble Space Telescope. We find the radial distributions that best describe the observed H2 FUV emission arising in primordial disk targets (full dust disk) are demonstrably different than those of transition disks (little-to-no warm dust observed). For each best-fit model, we estimate inner and outer disk emission boundaries (rin and rout), describing where the bulk of the observed H2 emission arises in each disk, and we examine correlations between these and several observational disk evolution indicators, such as n13-31, rin, CO, and the mass accretion rate. We find strong, positive correlations between the H2 radial distributions and the slope of the dust spectral energy distribution, implying the behavior of the molecular disk atmosphere changes as the inner dust clears in evolving PPDs. Overall, we find that H2 inner radii are ˜4 times larger in transition systems, while the bulk of the H2 emission originates inside the dust gap radius for all transitional sources.

  16. Clinical manifestations of celiac disease.

    PubMed

    Green, Peter H R; Krishnareddy, Suneeta; Lebwohl, Benjamin

    2015-01-01

    Celiac disease (CD) is an immune-based condition affecting multiple organ systems. Clinical manifestations are manifold in form and number due to the multisystem nature of CD. There has been a progressive change in the clinical manifestations over the recent decades with fewer patients, both adults and children, presenting with a diarrheal, classical form. This, in children, is seen in only the youngest, while growth issues, screening at-risk groups and recurrent abdominal pain are the most common modes of presentation among children. Among adults, diarrhea is the most common presentation followed by anemia. Screening at-risk groups, metabolic bone disease and incidental recognition at endoscopy performed for reflux are the other main modes of presentation. The bulk of those with CD remain undiagnosed. The symptoms are often common, and increased medical education should lead to greater awareness in the medical community and an increased rate of diagnosis. PMID:25925914

  17. Porphyria and its neurologic manifestations.

    PubMed

    Tracy, Jennifer A; Dyck, P James B

    2014-01-01

    Porphyrias are rare disorders resulting from a defect in the heme biosynthetic pathway. They can produce significant disease of both the peripheral and central nervous systems, in addition to other organ systems, with acute intermittent porphyria, hereditary coproporphyria, and variegate porphyria as the subtypes associated with neurologic manifestations. The presence of a motor-predominant peripheral neuropathy (axonal predominant), accompanied by gastrointestinal distress and neuropsychiatric manifestations, should be a strong clue to the diagnosis of porphyria. Clinical confirmation can be made through evaluation of urine porphyrins during an exacerbation of disease. While hematin is helpful for acute treatment, long-term effective management requires avoidance of overstimulation of the cytochrome P450 pathway, as well as other risk factor control. PMID:24365356

  18. Systemic diseases with cutaneous manifestations.

    PubMed

    Merchant, S R; Taboada, J

    1995-07-01

    The purpose of this article is to briefly discuss the following cutaneous manifestations of selected systemic diseases: poxvirus; feline leukemia virus (FeLV); feline immunodeficiency virus (FIV); herpesvirus; calcivirus; pseudorabies; plague; tularemia; toxoplasmosis; leishmania; hypothyroidism; hyperthyroidism; hyperadrenocorticism; diabetes mellitus; acromegaly; thallium poisoning; pancreatic disease; hypereosinophilic syndrome; mucopolysaccharidosis; and pansteatitis. Recognition of these cutaneous signs may help alert the clinician to the possibility of an internal disorder so that the appropriate diagnostic tests can be considered. PMID:8525575

  19. Reproductive manifestations of thyroid disease.

    PubMed

    Johnson, C A

    1994-05-01

    Thyroid function and reproductive function have many interactions, the scope and mechanism of which are not fully understood. These functions are of greatest clinical importance for veterinarians working with breeders of purebred dogs. Thyroid dysfunction does not always result in clinical signs of reproductive disorders or in subfertility. It seems that animals with overt thyroid dysfunction are those most likely to manifest reproduction problems. PMID:8053110

  20. Peritoneal manifestations of parasitic infection.

    PubMed

    Kim, So Yeon; Ha, Hyun Kwon

    2008-01-01

    The purpose of this study was to describe of peritoneal manifestations of parasitic infection at CT. A broad spectrum of CT findings can be seen in the peritoneal cavity, including a varying degree of omental or mesenteric infiltration, single or multiple peritoneal mass or nodule, and peritoneal thickening or stranding. Recognition of these findings are crucial for establish an early diagnosis and helps avoid unnecessary surgery. PMID:17924162

  1. Parasitic Diseases With Cutaneous Manifestations.

    PubMed

    Ash, Mark M; Phillips, Charles M

    2016-01-01

    Parasitic diseases result in a significant global health burden. While often thought to be isolated to returning travelers, parasitic diseases can also be acquired locally in the United States. Therefore, clinicians must be aware of the cutaneous manifestations of parasitic diseases to allow for prompt recognition, effective management, and subsequent mitigation of complications. This commentary also reviews pharmacologic treatment options for several common diseases. PMID:27621348

  2. Studies of Circumstellar Disk Evolution

    NASA Technical Reports Server (NTRS)

    Hartmann, Lee W.

    2005-01-01

    The aim of this project is to develop a comprehensive global picture of the physical conditions in, and evolutionary timescales of, pre-main sequence accretion disks. The results of this work will help constrain the initial conditions for planet formation. To this end we are developing much larger samples of 3-10 Myr-old stars to provide better empirical constraints on protoplanetary disk evolution; measuring disk accretion rates in these systems; and constructing detailed model disk structures consistent with observations to infer physical conditions such as grain growth in protoplanetary disks.

  3. Cutaneous manifestations of cystic fibrosis.

    PubMed

    Bernstein, Megan L; McCusker, Meagen M; Grant-Kels, Jane M

    2008-01-01

    Cystic fibrosis is an autosomal recessive disease reported in 1 in 2500 live births in Northern American and Northern European Caucasian populations. Classic disease findings include chronic bacterial infection of airways and sinuses, malabsorption of fat, infertility in men, and elevated concentrations of chloride in sweat. Less well-recognized findings associated with cystic fibrosis include cutaneous findings, which can be primary or secondary manifestations of the disease process. Patients demonstrate more atopic and drug hypersensitivity reactions than the general population, but have similar rates of urticaria compared with the general population. In atypical presentations of cystic fibrosis, the nutrient deficiency dermatitis of the disease may aid with diagnosis, and notably can be the presenting sign. Other dermatologic manifestations of cystic fibrosis include early aquagenic skin wrinkling and cutaneous vasculitis, which can be associated with arthralgias. Familiarity with the nutrient deficiency dermatitis of this entity may play a role in the timely diagnosis of the disease, and the other cutaneous findings add to our understanding of the protean nature of its manifestations. PMID:18429769

  4. Quantum Mechanics of Two Hard Disks within a Circle Billiard

    NASA Astrophysics Data System (ADS)

    Nakazono, N.; Kato, T.; Nakamura, K.

    We investigate a circular cavity billiard within which a pair of identical hard disks of smaller but finite size is confined. Each disk shows a free motion except bouncing elastically with its partner and with the boundary wall. Despite its circular symmetry, this system is nonintegrable and chaotic because of the (short-range) interaction between the disks. We quantize the system by incorporating the excluded volume effect for the wavefunction. Eigenvalues and eigenfunctions are obtained by tuning the relative size between the disks and the billiard. We define the effective volume V for the area where two disks can move freely and the pressure P, the derivative of each eigenvalue with respect to V. Reflecting the fact that the enegy spectra of eigenvalues versus the disk size show a multitude of level repulsions, P-V characteristics shows the anomalous fluctuations accompanied by many van der Waals-like peaks in each of individual excited eigenstates taken as a quasi-equilibrium. For each eigenfunction, we obtain the single particle density and two-particle correlation function, pointing out their relationship with the pressure fluctuations. Preliminary result on the feature of the corresponding classical dynamics is also given.

  5. Determination of elastic stresses in gas-turbine disks

    NASA Technical Reports Server (NTRS)

    Manson, S S

    1947-01-01

    A method is presented for the calculation of elastic stresses in symmetrical disks typical of those of a high-temperature gas turbine. The method is essentially a finite-difference solution of the equilibrium and compatibility equations for elastic stresses in a symmetrical disk. Account can be taken of point-to-point variations in disk thickness, in temperature, in elastic modulus, in coefficient of thermal expansion, in material density, and in Poisson's ratio. No numerical integration or trial-and-error procedures are involved and the computations can be performed in rapid and routine fashion by nontechnical computers with little engineering supervision. Checks on problems for which exact mathematical solutions are known indicate that the method yields results of high accuracy. Illustrative examples are presented to show the manner of treating solid disks, disks with central holes, and disks constructed either of a single material or two or more welded materials. The effect of shrink fitting is taken into account by a very simple device.

  6. 78 FR 11877 - Announcement of Requirements Gathering Meetings for the Electronic Manifest (e-Manifest) System

    Federal Register 2010, 2011, 2012, 2013, 2014

    2013-02-20

    ... inefficiencies associated with the use of paper manifest forms (66 FR 28240). Although comments generally... electronically completing and transmitting manifests through a national, centralized e-Manifest system (71 FR... AGENCY Announcement of Requirements Gathering Meetings for the Electronic Manifest (e-Manifest)...

  7. Brown dwarf disks with ALMA

    SciTech Connect

    Ricci, L.; Isella, A.; Testi, L.; De Gregorio-Monsalvo, I.; Natta, A.; Scholz, A.

    2014-08-10

    We present Atacama Large Millimeter/submillimeter Array continuum and spectral line data at 0.89 mm and 3.2 mm for three disks surrounding young brown dwarfs and very low mass stars in the Taurus star forming region. Dust thermal emission is detected and spatially resolved for all the three disks, while CO(J = 3-2) emission is seen in two disks. We analyze the continuum visibilities and constrain the disks' physical structure in dust. The results of our analysis show that the disks are relatively large; the smallest one has an outer radius of about 70 AU. The inferred disk radii, radial profiles of the dust surface density, and disk to central object mass ratios lie within the ranges found for disks around more massive young stars. We derive from our observations the wavelength dependence of the millimeter dust opacity. In all the three disks, data are consistent with the presence of grains with at least millimeter sizes, as also found for disks around young stars, and confirm that the early stages of the solid growth toward planetesimals occur also around very low-mass objects. We discuss the implications of our findings on models of solids evolution in protoplanetary disks, the main mechanisms proposed for the formation of brown dwarfs and very low-mass stars, as well as the potential of finding rocky and giant planets around very low-mass objects.

  8. Dark-disk universe.

    PubMed

    Fan, JiJi; Katz, Andrey; Randall, Lisa; Reece, Matthew

    2013-05-24

    We point out that current constraints on dark matter imply only that the majority of dark matter is cold and collisionless. A subdominant fraction of dark matter could have much stronger interactions. In particular, it could interact in a manner that dissipates energy, thereby cooling into a rotationally supported disk, much as baryons do. We call this proposed new dark matter component double-disk dark matter (DDDM). We argue that DDDM could constitute a fraction of all matter roughly as large as the fraction in baryons, and that it could be detected through its gravitational effects on the motion of stars in galaxies, for example. Furthermore, if DDDM can annihilate to gamma rays, it would give rise to an indirect detection signal distributed across the sky that differs dramatically from that predicted for ordinary dark matter. DDDM and more general partially interacting dark matter scenarios provide a large unexplored space of testable new physics ideas. PMID:23745856

  9. [Neuropsychiatric manifestations ushering pernicious anemia].

    PubMed

    Mrabet, S; Ellouze, F; Ellini, S; Mrad, M F

    2015-12-01

    Biermer disease or pernicious anemia is an autoimmune atrophic gastritis characterized by the lack of secretion of gastric intrinsic factor. This leads to an insufficient absorption of vitamin B12 in the ileum. Clinical manifestations are mainly hematologic. Neuropsychiatric manifestations are known but are less frequent especially early in the disease. Inaugural neuropsychiatric arrays are rare and various thus making diagnosis difficult. In this article, we report through two clinical cases different neuropsychiatric manifestations revealing pernicious anemia. Mrs. C.O., aged 56, presented after surgery for gallstones, an acute psychiatric array associated with gait disorders. She had no history of neurological or psychiatric problems. The psychiatric interview revealed delirious syndrome, depressive symptoms and anxiety. Neurological examination noted a flaccid paraplegia with peripheral neuropathic syndrome and myoclonus in the upper limbs. At the full blood count, a macrocytosis (VGM: 112.2fl) without anemia was found. The level of vitamin B12 in the blood was low. Cerebro-spinal MRI was suggestive of a neuro-Biermer and showed hyper signal in the cervical cord on T2-weighted sagittal section. In axial section, hyper signal appears at the posterior columns in the form of V. There were no brain abnormalities. A sensorimotor axonal polyneuropathy was diagnosed. The patient received vitamin B12 intramuscularly for ten days associated with neuroleptic treatment. Mrs. R.M., aged 40, was brought to the psychiatry consultation for acute behavioral disorders progressively worsening over a month. An anxiety syndrome, depressive syndrome and delirious syndrome were identified. Neurological examination showed a posterior cordonal syndrome with quadripyramidal syndrome. Full blood count showed a macrocytic anemia. Serum B12 level was collapsed. Cerebro-spinal MRI was normal. She received vitamin B12 with clinical and biological improvement. Features of pernicious anemia

  10. DISK-SATELLITE INTERACTION IN DISKS WITH DENSITY GAPS

    SciTech Connect

    Petrovich, Cristobal; Rafikov, Roman R.

    2012-10-10

    Gravitational coupling between a gaseous disk and an orbiting perturber leads to angular momentum exchange between them that can result in gap opening by planets in protoplanetary disks and clearing of gas by binary supermassive black holes (SMBHs) embedded in accretion disks. Understanding the co-evolution of the disk and the orbit of the perturber in these circumstances requires knowledge of the spatial distribution of the torque exerted by the latter on a highly non-uniform disk. Here we explore disk-satellite interaction in disks with gaps in linear approximation both in Fourier and in physical space, explicitly incorporating the disk non-uniformity in the fluid equations. Density gradients strongly displace the positions of Lindblad resonances in the disk (which often occur at multiple locations), and the waveforms of modes excited close to the gap edge get modified compared to the uniform disk case. The spatial distribution of the excitation torque density is found to be quite different from the existing prescriptions: most of the torque is exerted in a rather narrow region near the gap edge where Lindblad resonances accumulate, followed by an exponential falloff with the distance from the perturber. Despite these differences, for a given gap profile, the full integrated torque exerted on the disk agrees with the conventional uniform disk theory prediction at the level of {approx}10%. The nonlinearity of the density wave excited by the perturber is shown to decrease as the wave travels out of the gap, slowing down its nonlinear evolution and damping. Our results suggest that gap opening in protoplanetary disks and gas clearing around SMBH binaries can be more efficient than the existing theories predict. They pave the way for self-consistent calculations of the gap structure and the orbital evolution of the perturber using accurate prescription for the torque density behavior.

  11. Flow between contrarotating disks

    SciTech Connect

    Gan, X.; Kilic, M.; Owen, J.M.

    1995-04-01

    The paper describes a combined experimental and computational study of laminar and turbulent flow between contrarotating disks. Laminar computations produce Batchelor-type flow: radial outflow occurs in boundary layers on the disks and inflow is confined to a thin shear layer in the midplane; between the boundary layers and the shear layer, two contrarotating cores of fluid are formed. Turbulent computations (using a low-Reynolds-number {kappa}-{epsilon} turbulence model) and LDA measurements provide no evidence for Batchelor-type flow, even for rotational Reynolds numbers as low as 2.2 {times} 10{sup 4}. While separate boundary layers are formed on the disks, radial inflow occurs in a single interior core that extends between the two boundary layers; in the core, rotational effects are weak. Although the flow in the core was always found to be turbulent, the flow in the boundary layers could remain laminar for rotational Reynolds numbers up to 1.2 {times} 10{sup 5}. For the case of a superposed outflow, there is a source region in which the radial component of velocity is everywhere positive; radially outward of this region, the flow is similar to that described above. Although the turbulence model exhibited premature transition from laminar to turbulent flow in the boundary layers, agreement between the computed and measured radial and tangential components of velocity was mainly good over a wide range of nondimensional flow rates and rotational Reynolds numbers.

  12. AGN disks and black holes on the weighting scales

    NASA Astrophysics Data System (ADS)

    Huré, J.-M.; Hersant, F.; Surville, C.; Nakai, N.; Jacq, T.

    2011-06-01

    We exploit our formula for the gravitational potential of finite size, power-law disks to derive a general expression linking the mass of the black hole in active galactic nuclei (AGN), the mass of the surrounding disk, its surface density profile (through the power index s), and the differential rotation law. We find that the global rotation curve v(R) of the disk in centrifugal balance does not obey a power law of the cylindrical radius R (except in the confusing case s = -2 that mimics a Keplerian motion), and discuss the local velocity index. This formula can help to understand how, from position-velocity diagrams, mass is shared between the disk and the black hole. To this purpose, we checked the idea by generating a sample of synthetic data with different levels of Gaussian noise, added in radius. It turns out that, when observations are spread over a large radial domain and exhibit low dispersion (standard deviation σ ≲ 10% typically), the disk properties (mass and s-parameter) and black hole mass can be deduced from a non linear fit of kinematic data plotted on a (R,Rv2)-diagram. For σ ≳ 10%, masses are estimated fairly well from a linear regression (corresponding to the zeroth-order treatment of the formula), but the power index s is no longer accessible. We have applied the model to 7 AGN disks whose rotation has already been probed through water maser emission. For NGC 3393 and UGC 3789, the masses seem well constrained through the linear approach. For IC 1481, the power-law exponent s can even be deduced. Because the model is scale-free, it applies to any kind of star/disk system. Extension to disks around young stars showing deviation from Keplerian motion is thus straightforward.

  13. Noncircular outer disks in unbarred S0 galaxies: NGC 502 and NGC 5485

    NASA Astrophysics Data System (ADS)

    Sil'chenko, O. K.

    2016-03-01

    Highly noncircular outer stellar disks have been detected in two SA0 (unbarred) galaxies by comparing the spectroscopic data on the rotation of stars and the photometric data on the shape and orientation of isophotes. In NGC 502, the oval distortion of the disk is manifested in the shape of the inner and outer elliptical rings occupying wide radial zones between the bulge and the disk and at the outer disk edge; such a structure can be a consequence of the so-called "dry minor merger," multiple cannibalization of gas-free satellites. In NGC 5485, the stellar kinematics is absolutely unrelated to the orientation of isophotes in the disk region, and for this galaxy the conclusion about its global triaxial structure is unavoidable.

  14. DVD - digital versatile disks

    SciTech Connect

    Gaunt, R.

    1997-05-01

    An international standard has emerged for the first true multimedia format. Digital Versatile Disk (by its official name), you may know it as Digital Video Disks. DVD has applications in movies, music, games, information CD-ROMS, and many other areas where massive amounts of digital information is needed. Did I say massive amounts of data? Would you believe over 17 gigabytes on a single piece of plastic the size of an audio-CD? That`s the promise, at least, by the group of nine electronics manufacturers who have agreed to the format specification, and who hope to make this goal a reality by 1998. In this major agreement, which didn`t come easily, the manufacturers will combine Sony and Phillip`s one side double-layer NMCD format with Toshiba and Matsushita`s double sided Super-Density disk. By Spring of this year, they plan to market the first 4.7 gigabyte units. The question is: Will DVD take off? Some believe that read-only disks recorded with movies will be about as popular as video laser disks. They say that until the eraseable/writable DVD arrives, the consumer will most likely not buy it. Also, DVD has a good market for replacement of CD- Roms. Back in the early 80`s, the international committee deciding the format of the audio compact disk decided its length would be 73 minutes. This, they declared, would allow Beethoven`s 9th Symphony to be contained entirely on a single CD. Similarly, today it was agreed that playback length of a single sided, single layer DVD would be 133 minutes, long enough to hold 94% of all feature-length movies. Further, audio can be in Dolby`s AC-3 stereo or 5.1 tracks of surround sound, better than CD-quality audio (16-bits at 48kHz). In addition, there are three to five language tracks, copy protection and parental ``locks`` for R rated movies. DVD will be backwards compatible with current CD-ROM and audio CD formats. Added versatility comes by way of multiple aspect rations: 4:3 pan-scan, 4:3 letterbox, and 16:9 widescreen. MPEG

  15. ACCRETION OUTBURSTS IN CIRCUMPLANETARY DISKS

    SciTech Connect

    Lubow, S. H.; Martin, R. G.

    2012-04-20

    We describe a model for the long-term evolution of a circumplanetary disk that is fed mass from a circumstellar disk and contains regions of low turbulence (dead zones). We show that such disks can be subject to accretion-driven outbursts, analogous to outbursts previously modeled in the context of circumstellar disks to explain FU Ori phenomena. Circumplanetary disks around a proto-Jupiter can undergo outbursts for infall accretion rates onto the disks in the range M-dot{sub infall} approx. 10{sup -9} to 10{sup -7} M{sub Sun} yr{sup -1}, typical of accretion rates in the T Tauri phase. During outbursts, the accretion rate and disk luminosity increases by several orders of magnitude. Most of the planet mass growth during planetary gas accretion may occur via disk outbursts involving gas that is considerably hotter than predicted by steady state models. For low infall accretion rates M-dot{sub infall} {approx}< 10{sup -10} M{sub sun} yr{sup -1} that occur in late stages of disk accretion, disk outbursts are unlikely to occur, even if dead zones are present. Such conditions are favorable for the formation of icy satellites.

  16. BINARIES AMONG DEBRIS DISK STARS

    SciTech Connect

    Rodriguez, David R.; Zuckerman, B.

    2012-02-01

    We have gathered a sample of 112 main-sequence stars with known debris disks. We collected published information and performed adaptive optics observations at Lick Observatory to determine if these debris disks are associated with binary or multiple stars. We discovered a previously unknown M-star companion to HD 1051 at a projected separation of 628 AU. We found that 25% {+-} 4% of our debris disk systems are binary or triple star systems, substantially less than the expected {approx}50%. The period distribution for these suggests a relative lack of systems with 1-100 AU separations. Only a few systems have blackbody disk radii comparable to the binary/triple separation. Together, these two characteristics suggest that binaries with intermediate separations of 1-100 AU readily clear out their disks. We find that the fractional disk luminosity, as a proxy for disk mass, is generally lower for multiple systems than for single stars at any given age. Hence, for a binary to possess a disk (or form planets) it must either be a very widely separated binary with disk particles orbiting a single star or it must be a small separation binary with a circumbinary disk.

  17. [Vectorcardiographic manifestations of atrial enlargements].

    PubMed

    de Micheli, A; Medrano, G A

    1990-01-01

    Rational interpretation of changes of the P loop due to atrial enlargements must to rely on the magnitude and spatial orientation of main resultant vectors of the activation sequence of the atria. Under normal conditions, these vectors give rise to a mean vector oriented to the left downward and discretely forward with respect to their point of origin. In the presence of right atrial enlargement, the manifestation of the first vector of atrial depolarization, oriented downward and forward, is increased. This one moves in the same direction as the mean vector of atrial depolarization, originating an elongated P loop of more than 100 mcv in the three planes. Nevertheless, in the horizontal plane, increase of the P loop voltage predominates when hypertrophy exists, while augmentation of its area predominates when dilatation exists. In left atrial enlargement, the manifestation of the second vector of atrial depolarization, oriented to the left and backward, is augmented, and it moves in the same direction as the mean vector of atrial depolarization. For this, the PF loop acquires a characteristic aspect of a boxing glove, an the PH loop becomes diphasic, with its posterior area more or less prominent, or with a typical figure-eight conformation. If a biatrial enlargement is present, the manifestation of both the main resultant vectors of atrial depolarization is accentuated. Therefore the voltage of the diphasic P loop increases. Moreover the Ps loop has a triangular configuration, with its base of 30 msc or more, located below its point of origin. Generally disturbances of interatrial and intraatrial conduction coexist owing to myocardial damage. PMID:2146934

  18. Clinical manifestation of mitochondrial diseases.

    PubMed

    Magner, Martin; Kolářová, Hana; Honzik, Tomáš; Švandová, Ivana; Zeman, Jiří

    2015-01-01

    Mitochondrial disorders (MD) represent a clinically, biochemically and genetically heterogeneous group of diseases associated with dysfunction of the oxidative phosphorylation system and pyruvate dehydrogenase complex. Our aim was to illustrate the most common clinical presentation of MD on the example of selected diseases and syndromes. The minimal prevalence of MD is estimated as 1 to 5,000. MD may manifest at any age since birth until late-adulthood with acute manifestation or as a chronic progressive disease. Virtually any organ may be impaired, but the organs with the highest energetic demands are most frequently involved, including brain, muscle, heart and liver. Some MD may manifest as a characteristic cluster of clinical features (e.g. MELAS syndrome, Kearns-Sayre syndrome). Diagnostics includes detailed history, the comprehensive clinical examination, results of specialized examinations (especially cardiology, visual fundus examination, brain imaging, EMG), laboratory testing of body fluids (lactate, aminoacids, organic acids), and analysis of bioptic samples of muscle, skin, and liver, eventually. Normal lactate level in blood does not exclude the possibility of MD. Although the aimed molecular genetic analyses may be indicated in some of mitochondrial diseases, the methods of next generation sequencing come into focus. Examples of treatment are arginine supplementation in MELAS syndrome, ketogenic diet in pyruvate oxidation disorders or quinone analogs in patients with LHON. Conclusion: The clinical suspicion of a mitochondrial disorder is often delayed, or the disease remains undiagnosed. The correct diagnosis and adequate treatment can improve prognosis of the patient. Access to genetic counseling is also of great importance. PMID:26982751

  19. Cardiac manifestations in systemic sclerosis

    PubMed Central

    Lambova, Sevdalina

    2014-01-01

    Primary cardiac involvement, which develops as a direct consequence of systemic sclerosis (SSc), may manifest as myocardial damage, fibrosis of the conduction system, pericardial and, less frequently, as valvular disease. In addition, cardiac complications in SSc may develop as a secondary phenomenon due to pulmonary arterial hypertension and kidney pathology. The prevalence of primary cardiac involvement in SSc is variable and difficult to determine because of the diversity of cardiac manifestations, the presence of subclinical periods, the type of diagnostic tools applied, and the diversity of patient populations. When clinically manifested, cardiac involvement is thought to be an important prognostic factor. Profound microvascular disease is a pathognomonic feature of SSc, as both vasospasm and structural alterations are present. Such alterations are thought to predict macrovascular atherosclerosis over time. There are contradictory reports regarding the prevalence of atherosclerosis in SSc. According to some authors, the prevalence of atherosclerosis of the large epicardial coronary arteries is similar to that of the general population, in contrast with other rheumatic diseases such as rheumatoid arthritis and systemic lupus erythematosus. However, the level of inflammation in SSc is inferior. Thus, the atherosclerotic process may not be as aggressive and not easily detectable in smaller studies. Echocardiography (especially tissue Doppler imaging), single-photon emission computed tomography, magnetic resonance imaging and cardiac computed tomography are sensitive techniques for earlier detection of both structural and functional scleroderma-related cardiac pathologies. Screening for subclinical cardiac involvement via modern, sensitive tools provides an opportunity for early diagnosis and treatment, which is of crucial importance for a positive outcome. PMID:25276300

  20. Clinical manifestations of sleep apnea

    PubMed Central

    2015-01-01

    Obstructive sleep apnea (OSA) may manifest in a number of ways from subtle intrusion into daily life to profound sleepiness, snoring, witnessed apneas and other classic symptoms. Although there is increasing evidence suggesting OSA can adversely affect health in a variety of ways, this disorder remains underdiagnosed. The most well-escribed health consequences of OSA relate to the cardiovascular system. Hypertension and arrhythmias have a strong association with OSA, and evidence suggests that treatment of OSA in patients with refractory hypertension and in patients planning cardioversion for atrial fibrillation may be of particularly importance. Significant associations between heart failure and OSA as well as complex sleep apnea have also been well-described. Cerebrovascular insult, impaired neurocognition, and poorly controlled mood disorder are also associated with in OSA. Therapy for OSA may ameliorate atherosclerotic progression and improve outcomes post-cerebrovascular accident (CVA). OSA should be considered in patients complaining of poor concentration at work, actual or near-miss motor vehicle accidents, and patients with severe sleepiness as a component of their co-morbid mood disorders. The metabolic impact of OSA has also been studied, particularly in relation to glucose homeostasis. Also of interest is the potential impact OSA has on lipid metabolism. The adverse effect untreated OSA has on glucose tolerance and lipid levels has led to the suggestion that OSA is yet another constituent of the metabolic syndrome. Some of these metabolic derangements may be related to the adverse effects untreated OSA has on hepatic health. The cardiovascular, neurocognitive, and metabolic manifestations of OSA can have a significant impact on patient health and quality of life. In many instances, evidence exists that therapy not only improves outcomes in general, but also modifies the severity of co-morbid disease. To mitigate the long-term sequela of this disease

  1. Cutaneous manifestation of gastrointestinal disease

    PubMed Central

    Kerstetter, Justin

    2016-01-01

    The gastrointestinal (GI) and cutaneous systems are closely linked in origin. Skin manifestations are frequently seen as a part of different GI syndromes. Gastroenterologists play an important role in recognizing the symptoms, patient workup and arriving at appropriate diagnoses, often in consultation with dermatologists. This review discusses the diseases with both cutaneous and intestinal involvement. Hereditary polyposis GI cancers, hereditary nonpolyposis colorectal cancers (CRCs), hamartomatous disorders, and inflammatory bowel disease (IBD) are reviewed with emphasis on the genetic basis, diagnostic, histologic findings, screening modalities, and therapeutic options. PMID:27034812

  2. Musculoskeletal manifestations of endocrine disorders.

    PubMed

    Boswell, Stephanie B; Patel, Dakshesh B; White, Eric A; Gottsegen, Christopher J; Forrester, Deborah M; Masih, Sulabha; Matcuk, George R

    2014-01-01

    Endocrine disorders can lead to disturbances in numerous systems within the body, including the musculoskeletal system. Radiological evaluation of these conditions can demonstrate typical appearances of the bones and soft tissues. Knowledge of these patterns can allow the radiologist to suggest a diagnosis that may not be clinically apparent. This review will highlight the typical musculoskeletal findings of acromegaly, hypercortisolism, hyperthyroidism, hypothyroidism, hyperparathyroidism, pseudo- and pseudopseudohypoparathyroidism, and diabetes mellitus. The radiological manifestations of each of these endocrine disorders, along with a brief discussion of the pathophysiology and clinical implications, will be discussed. PMID:24642251

  3. Cutaneous manifestations associated with melanoma.

    PubMed

    Vyas, Ritva; Selph, Jacqueline; Gerstenblith, Meg R

    2016-06-01

    Melanoma is a malignancy most commonly arising from the skin; therefore, primary melanoma characteristics are usually the first cutaneous manifestations of melanoma. Cutaneous metastases, which can occur locally or diffusely, are important to detect in a timely manner as treatments for advanced melanoma that impact survival are now available. Melanoma can be associated with local or diffuse pigmentation changes, including depigmentation associated with the leukodermas and hyperpigmentation associated with diffuse melanosis cutis. The leukodermas occur frequently, illustrate the immunogenic nature of melanoma, and may impact prognosis. Paraneoplastic syndromes in association with melanoma are rare, though can occur. PMID:27178692

  4. An experimental investigation of a gas turbine disk cooling system

    NASA Astrophysics Data System (ADS)

    Kobayashi, N.; Matsumato, M.; Shizuya, M.

    1983-03-01

    The results of an experimental study of the cooling of a model disk similar to an engine disk are compared with the results obtained by three-dimensional finite difference computation, and it is reconfirmed that the determination of cooling air temperature is one of the most important data for predicting the disk temperature. The minimum cooling air flow rate necessary to prevent ingress of external hot gas is determined by the fluctuation of cooling air temperature inside the wheel space with the external axial hot gas flow for values of the rotational Reynolds number of 0-6.5 million. The effect of rotational speed on the minimum cooling air flow rate is found to be negligible, and it is shown that the determination of the ingress of hot gas using the pressure difference criterion underestimates the minimum cooling air flow rate.

  5. Possible experimental manifestations of the many-body localization

    NASA Astrophysics Data System (ADS)

    Basko, D. M.; Aleiner, I. L.; Altshuler, B. L.

    2007-08-01

    Recently, it was predicted that if all one-electron states in a noninteracting disordered system are localized, the interaction between electrons in the absence of coupling to phonons leads to a finite-temperature metal-insulator transition. Here, we show that even in the presence of a weak coupling to phonons the transition manifests itself (i) in the nonlinear conduction, leading to a bistable I-V curve, and (ii) by a dramatic enhancement of the nonequilibrium current noise near the transition.

  6. Coronal manifestations of preflare activity

    NASA Technical Reports Server (NTRS)

    Schmahl, E. J.; Webb, D. F.; Woodgate, B.; Waggett, P.; Bentley, R.; Hurford, G.; Schadee, A.; Schrijver, J.; Harrison, R.; Martens, P.

    1986-01-01

    A variety of coronal manifestations of precursors or preheating for flares are discussed. Researchers found that almost everyone with a telescope sees something before flares. Whether an all-encompassing scenario will ever be developed is not at all clear at present. The clearest example of preflare activity appears to be activated filaments and their manifestations, which presumably are signatures of a changing magnetic field. But researchers have seen two similar eruptions, one without any evidence of emerging flux (Kundu et al., 1985) and the other with colliding poles (Simon et al., 1984). While the reconnection of flux is generally agreed to be required to energize a flare, the emergence of flux from below (at least on short timescales and in compact regions) does not appear to be a necessary condition. In some cases the cancelling of magnetic flux (Martin, 1984) by horizontal motions instead may provide the trigger (Priest, 1985) Researchers found similarities and some differences between these and previous observations. The similarities, besides the frequent involvement of filaments, include compact, multiple precursors which can occur both at and near (not at) the flare site, and the association between coronal sources and activity lower in the atmosphere (i.e., transition zone and chromosphere).

  7. 40 CFR 761.210 - Manifest discrepancies.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.210 Manifest discrepancies. (a) Manifest discrepancies are differences between the quantity or type of PCB waste designated on the manifest or shipping paper and the quantity or type of PCB waste actually delivered to and received by a designated...

  8. 40 CFR 761.215 - Manifest discrepancies.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.215 Manifest discrepancies. (a) Manifest... quantity or type of PCB waste designated on the manifest or shipping paper, and the quantity and type of PCB waste a facility actually receives; or (2) Rejected wastes, which may be a full or...

  9. 40 CFR 761.210 - Manifest discrepancies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.210 Manifest discrepancies. (a) Manifest discrepancies are differences between the quantity or type of PCB waste designated on the manifest or shipping paper and the quantity or type of PCB waste actually delivered to and received by a designated...

  10. 40 CFR 761.215 - Manifest discrepancies.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.215 Manifest discrepancies. (a) Manifest... quantity or type of PCB waste designated on the manifest or shipping paper, and the quantity and type of PCB waste a facility actually receives; or (2) Rejected wastes, which may be a full or...

  11. 40 CFR 761.210 - Manifest discrepancies.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.210 Manifest discrepancies. (a) Manifest discrepancies are differences between the quantity or type of PCB waste designated on the manifest or shipping paper and the quantity or type of PCB waste actually delivered to and received by a designated...

  12. C/C composite brake disk nondestructive evaluation by IR thermography

    NASA Astrophysics Data System (ADS)

    Chu, Tsuchin P.; Poudel, Anish; Filip, Peter

    2012-06-01

    This paper discusses the non-destructive evaluation of thick Carbon/Carbon (C/C) composite aircraft brake disks by using transient infrared thermography (IRT) approach. Thermal diffusivity measurement technique was applied to identify the subsurface anomalies in thick C/C brake disks. In addition, finite element analysis (FEA) modeling tool was used to determine the transient thermal response of the C/C disks that were subjected to flash heating. For this, series of finite element models were built and thermal responses with various thermal diffusivities subjected to different heating conditions were investigated. Experiments were conducted to verify the models by using custom built in-house IRT system and commercial turnkey system. The analysis and experimental results showed good correlation between thermal diffusivity value and anomalies within the disk. It was demonstrated that the step-heating transient thermal approach could be effectively applied to obtain the whole field thermal diffusivity value of C/C composites.

  13. Structural Optimization Methodology for Rotating Disks of Aircraft Engines

    NASA Technical Reports Server (NTRS)

    Armand, Sasan C.

    1995-01-01

    In support of the preliminary evaluation of various engine technologies, a methodology has been developed for structurally designing the rotating disks of an aircraft engine. The structural design methodology, along with a previously derived methodology for predicting low-cycle fatigue life, was implemented in a computer program. An interface computer program was also developed that gathers the required data from a flowpath analysis program (WATE) being used at NASA Lewis. The computer program developed for this study requires minimum interaction with the user, thus allowing engineers with varying backgrounds in aeropropulsion to successfully execute it. The stress analysis portion of the methodology and the computer program were verified by employing the finite element analysis method. The 10th- stage, high-pressure-compressor disk of the Energy Efficient Engine Program (E3) engine was used to verify the stress analysis; the differences between the stresses and displacements obtained from the computer program developed for this study and from the finite element analysis were all below 3 percent for the problem solved. The computer program developed for this study was employed to structurally optimize the rotating disks of the E3 high-pressure compressor. The rotating disks designed by the computer program in this study were approximately 26 percent lighter than calculated from the E3 drawings. The methodology is presented herein.

  14. Ringed Accretion Disks: Instabilities

    NASA Astrophysics Data System (ADS)

    Pugliese, D.; Stuchlík, Z.

    2016-04-01

    We analyze the possibility that several instability points may be formed, due to the Paczyński mechanism of violation of mechanical equilibrium, in the orbiting matter around a supermassive Kerr black hole. We consider a recently proposed model of a ringed accretion disk, made up by several tori (rings) that can be corotating or counter-rotating relative to the Kerr attractor due to the history of the accretion process. Each torus is governed by the general relativistic hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. We prove that the number of the instability points is generally limited and depends on the dimensionless spin of the rotating attractor.

  15. Supermassive disk galaxies

    NASA Astrophysics Data System (ADS)

    Buson, L. M.; Galletta, G.; Saglia, R. P.; Zeilinger, W. W.

    1991-03-01

    In order to investigate the properties of supermassive disk galaxies (SDGs), an extensive optical survey of SDG candidates in the Southern Hemisphere was performed with the 2.2-m ESO/MPI telescope at La Silla. The question of whether SDGs have in general an unusually high content of dark matter in the inner regions or, perhaps, an unusual stellar population is addressed. It is suggested that SDGs are formed as the result of a series of accretion events, possibly induced also by the progressive deepening of the galaxy potential well.

  16. Optical disk media research discussed

    NASA Astrophysics Data System (ADS)

    Hou, J.; Gan, F.

    1986-03-01

    A review of the current status of the research and development on various optical disk media is presented. It is noted that research around the world on the media for the nonerasable optical disk is almost over, and that the nonerasable optical disk has been successfully used for CD, LD player and DRAW devices. On the other hand, great efforts are now being made to search the more suitable media for erasable optical disks. Extensive experiments on various material systems including optical characteristic change, phase transition and magneto-optical recording media are under way. It is expected that fruitful results will appear in the next 2 or 3 years.

  17. Gravitational Instability in Planetesimal Disks

    NASA Astrophysics Data System (ADS)

    Bolin, Bryce T.; Lithwick, Yoram; Pan, Margaret; Rein, Hanno; Wu, Yanqin

    2014-11-01

    Gravitational instability (GI) has been proposed as a method of forming giant gas planets enhanced by disk thermodynamics in a protoplanetary disk (Boss, 1997, Science 276; Durisen et al., 2007, Protostars and Planets V) and as a method of forming planetesimals through the focusing of boulders by the interaction between solids and gases in a turbulent circumstellar disk (Johansen et al., 2007, Nature 448; Youdin & Goodman, 2005, Astrophys. J. 620). GI is mediated through a gaseous circumstellar disk in each each of these scenarios. We explore the possibility of GI occurring in a planetesimal disk devoid of gas. In this regime, mutual collisions between planetesimals are required to dissipate their orbital shear and velocity dispersion enough for collapse to occur as described by the Toomre stability criterion (Toomre, 1964, Astrophys. J. 139; Toomre, 1981, Structure and Evolution of Normal Galaxies). How frequent must collisions be between planetesimals in a gravitationally stable planetesimal disk for GI to occur? Are there collisional rates where GI is postponed indefinitely in an equilibrium state between gravitational stirring and collisional cooling? We present 3D shearing sheet simulations using the REBOUND N-body code with the symplectic epicyclic integrator (Rein & Liu, 2011, A&A 537; Rein & Tremaine, 2011, MNRAS 415) in which the candidate collision rates are within a few orders of magnitude of the disk dynamical lifetime. Our simulations suggest that collisions rate directly controls disk cooling. The shape of the disk cooling curve is independent of the collision rate when scaled to the collision time.

  18. [Disk calcifications in children].

    PubMed

    Schmit, P; Fauré, C; Denarnaud, L

    1985-05-01

    It is not unusual for intervertebral disk calcifications to be detected in pediatric practice, the 150 or so cases reported in the literature probably representing only a small proportion of lesions actually diagnosed. Case reports of 33 children with intervertebral disk calcifications were analyzed. In the majority of these patients (31 of 33) a diagnosis of "idiopathic" calcifications had been made, the cervical localization of the lesions being related to repeated ORL infections and/or trauma. A pre-existing pathologic factor was found in two cases (one child with juvenile rheumatoid arthritis treated by corticoids and one child with Williams and Van Beuren's syndrome). An uncomplicated course was noted in 31 cases, the symptomatology (pain, spinal stiffness and febricula) improving after several days. Complications developed in two cases: one child had very disabling dysphagia due to an anteriorly protruding cervical herniated disc and surgery was necessary; the other child developed cervicobrachial neuralgia due to herniated disc protrusion into the cervical spinal canal, but symptoms regressed within several days although calcifications persisted unaltered. These findings and the course of the rare complications documented in the literature suggest the need for the most conservative treatment possible in cases of disc calcifications in children. PMID:4032343

  19. Disk storage at CERN

    NASA Astrophysics Data System (ADS)

    Mascetti, L.; Cano, E.; Chan, B.; Espinal, X.; Fiorot, A.; González Labrador, H.; Iven, J.; Lamanna, M.; Lo Presti, G.; Mościcki, JT; Peters, AJ; Ponce, S.; Rousseau, H.; van der Ster, D.

    2015-12-01

    CERN IT DSS operates the main storage resources for data taking and physics analysis mainly via three system: AFS, CASTOR and EOS. The total usable space available on disk for users is about 100 PB (with relative ratios 1:20:120). EOS actively uses the two CERN Tier0 centres (Meyrin and Wigner) with 50:50 ratio. IT DSS also provide sizeable on-demand resources for IT services most notably OpenStack and NFS-based clients: this is provided by a Ceph infrastructure (3 PB) and few proprietary servers (NetApp). We will describe our operational experience and recent changes to these systems with special emphasis to the present usages for LHC data taking, the convergence to commodity hardware (nodes with 200-TB each with optional SSD) shared across all services. We also describe our experience in coupling commodity and home-grown solution (e.g. CERNBox integration in EOS, Ceph disk pools for AFS, CASTOR and NFS) and finally the future evolution of these systems for WLCG and beyond.

  20. Disk MHD generator study

    NASA Technical Reports Server (NTRS)

    Retallick, F. D.

    1980-01-01

    Directly-fired, separately-fired, and oxygen-augmented MHD power plants incorporating a disk geometry for the MHD generator were studied. The base parameters defined for four near-optimum-performance MHD steam power systems of various types are presented. The finally selected systems consisted of (1) two directly fired cases, one at 1920 K (2996F) preheat and the other at 1650 K (2500 F) preheat, (2) a separately-fired case where the air is preheated to the same level as the higher temperature directly-fired cases, and (3) an oxygen augmented case with the same generator inlet temperature of 2839 (4650F) as the high temperature directly-fired and separately-fired cases. Supersonic Mach numbers at the generator inlet, gas inlet swirl, and constant Hall field operation were specified based on disk generator optimization. System pressures were based on optimization of MHD net power. Supercritical reheat stream plants were used in all cases. Open and closed cycle component costs are summarized and compared.

  1. Cutaneous manifestations of lung cancer.

    PubMed

    Owen, Cindy England

    2016-06-01

    Skin findings can serve as a clue to internal disease. In this article, cutaneous manifestations of underlying lung malignancy are reviewed. Paraneoplastic dermatoses are rare, but when recognized early, can lead to early diagnosis of an underlying neoplasm. Malignancy-associated dermatoses comprise a broad group of hyperproliferative and inflammatory disorders, disorders caused by tumor production of hormonal or metabolic factors, autoimmune connective tissue diseases, among others. In this review, paraneoplastic syndromes associated with lung malignancy are discussed, including ectopic ACTH syndrome, bronchial carcinoid variant syndrome, secondary hypertrophic osteoarthropathy/digital clubbing, erythema gyratum repens, malignant acanthosis nigricans, sign of Leser-Trélat, tripe palms, hypertrichosis lanuginosa, acrokeratosis paraneoplastica, and dermatomyositis. PMID:27178690

  2. Oral manifestations in transplant patients

    PubMed Central

    Nappalli, Deepika; Lingappa, Ashok

    2015-01-01

    Organ transplantation is a widely undertaken procedure and has become an important alternative for the treatment of different end-stage organ diseases that previously had a poor prognosis. The field of organ transplant and hematopoietic stem cell transplant is developing rapidly. The increase in the number of transplant recipients also has an impact on oral and dental services. Most of the oral problems develop as a direct consequence of drug-induced immunosuppression or the procedure itself. These patients may present with oral complaints due to infections or mucosal lesions. Such lesions should be identified, diagnosed, and treated. New treatment strategies permit continuous adaptation of oral care regimens to the changing scope of oral complications. The aim of this review is to analyze those oral manifestations and to discuss the related literature. PMID:26005458

  3. Hematologic manifestations of celiac disease

    PubMed Central

    Halfdanarson, Thorvardur R.; Litzow, Mark R.; Murray, Joseph A.

    2007-01-01

    Celiac disease is a common systemic disorder that can have multiple hematologic manifestations. Patients with celiac disease may present to hematologists for evaluation of various hematologic problems prior to receiving a diagnosis of celiac disease. Anemia secondary to malabsorption of iron, folic acid, and/or vitamin B12 is a common complication of celiac disease and many patients have anemia at the time of diagnosis. Celiac disease may also be associated with thrombocytosis, thrombocytopenia, leukopenia, venous thromboembolism, hyposplenism, and IgA deficiency. Patients with celiac disease are at increased risk of being diagnosed with lymphoma, especially of the T-cell type. The risk is highest for enteropathy-type T-cell lymphoma (ETL) and B-cell lymphoma of the gut, but extraintestinal lymphomas can also be seen. ETL is an aggressive disease with poor prognosis, but strict adherence to a gluten-free diet may prevent its occurrence. PMID:16973955

  4. Clinical manifestations in trisomy 9.

    PubMed

    Kannan, T P; Hemlatha, S; Ankathil, R; Zilfalil, B A

    2009-07-01

    Complete trisomy 9 is a lethal diagnosis and most fetuses diagnosed thus die prenatally or during the early postnatal period and majority of such cases have been known to end in spontaneous abortion in the first trimester itself. One such rare survival of fetus ending in normal delivery and surviving until 20 days is reported here detailing the clinical manifestations of the child during the period of survival. The salient clinical features observed were small face, wide fontanel, prominent occiput, micrognathia, low set ears, upslanting palpebral fissures, high arched palate, short sternum, overlapping fingers, limited hip abduction, rocker bottom feet, heart murmurs and also webbed neck, characteristic of this trisomy 9 syndrome. PMID:19475342

  5. [Purpura: primary systemic amyloidosis manifestation].

    PubMed

    Lestre, Sara; Gonçalves, Andreia; João, Alexandre; Ferreira, Ana; Apetato, Margarida

    2009-01-01

    Primary Systemic Amyloidosis (AL) is the most frequent form of systemic amyloidosis and its morbilility is associated with immunoglobulin light chains deposition in vital organs. The mucocutaneous manifestations occur in about 30-40% of the cases and are important in diagnostic suspicion, once they appear in early stages of disease. We report a 71-years-old female patient, with disseminated purpura and cutaneous fragility with 6 months of evolution, accompanied by recent complaints of dysphagy. The first laboratory evaluation didn't show any alterations. The histological and immunohistochemical study of subcutaneous abdominal fat and skin biopsy showed lambda type amyloid protein. In the systemic work-up, we highlight a proteinúria > 1g/24h with Bence Jones proteins and the presence of monoclonal immunoglobulin light chain (lambda type) in serum immunoelectrophoresis. With the diagnosis of primary systemic amyloidosis, treatment with prednisolone and melphalan was started. PMID:19686633

  6. Model scattering envelopes of young stellar objects. I - Method and application to circumstellar disks

    NASA Technical Reports Server (NTRS)

    Whitney, Barbara A.; Hartmann, Lee

    1992-01-01

    We describe a Monte Carlo code that accurately treats multiple scattering, absorption, and polarization by dust, and use this code to calculate images of dusty disks around young stellar objects. We present some approximate analytic results that describe the behavior of the Monte Carlo calculations. A geometrically thin disk illuminated by a central T Tauri star scatters very little light at distances of many AU from the star. Viewed at any inclination, the flux scattered by such a disk at the distance to the nearest star-forming region will be overwhelmed by the stellar image. An optically thick disk that has a flaring surface may be observable, especially if viewed nearly edge-on so that the stellar source becomes occulted. An optically thin disk with a finite opening angle, similar to the one surrounding beta Pictoris, is about as observable as the typical flared optically thick disk at a similar distance from the earth. The polarization position angle is perpendicular to the disk plane in all of the models, in contrast to observations of many young stellar objects which have the position angle oriented parallel to the presumed disk plane. We suggest that the scattered light structures observed around many premain-sequence objects are dusty envelopes rather than disks.

  7. A twisted disk equation that describes warped galaxy disks

    NASA Technical Reports Server (NTRS)

    Barker, K.

    1994-01-01

    Warped H1 gas layers in the outer regions of spiral galaxies usually display a noticeably twisted structure. This structure is thought to arise primarily as a result of differential precession in the H1 disk as it settles toward a 'preferred orientation' in an underlying dark halo potential well that is not spherically symmetric. In an attempt to better understand the structure and evolution of these twisted, warped disk structures, we have utilized the 'twist-equation' formalism. Specifically, we have generalized the twist equation to allow the treatment of non-Keplerian disks and from it have derived the steady-state structure of twisted disks that develop from free precession in a nonspherical, logarithmic halo potential. This generalized equation can also be used to examine the time-evolutionary behavior of warped galaxy disks.

  8. Effectiveness of a disk-type magnetorheologic fluid damper for rotor system vibration control

    NASA Astrophysics Data System (ADS)

    Zhu, Changsheng; Robb, David A.; Ewins, David J.

    2001-07-01

    A disk-type MR fluid damper based on shear operation mode is presented in this paper. The magnetic field of the disk-type MR fluid damper is analysed by the finite element method. The effect of excitation current in the coil on the magnetic flux density in the axial gaps filled with MR fluid is studied both theoretically and experimentally. Finally, the effectiveness of the disk-type MR fluid damper for attenuating vibration of rotor systems and of a simple open-loop on-off control based on the feedback of rotational speed on controlling vibration of rotor systems are experimentally studied. It is shown that the dynamic characteristics of the disk-type MR fluid damper can be controlled by a simple magnetic coil with a low voltage, and the disk-type MR fluid damper is very effective to attenuate vibration of rotor systems.

  9. An investigation of the vibration characteristics of shrouded-bladed-disk rotor stages

    NASA Technical Reports Server (NTRS)

    Chen, L.-T.; Dugundji, J.

    1979-01-01

    Coupled differential equations of motion are given for application to a rotating, pretwisted and heated beam under the effects of thermal stresses and gas bending loads. The circumferential modes of the multi-blade vibration of a bladed-disk rotor stage were studied. A finite element method was developed for the dynamic and static deformation analysis of the blade. The deformations of a bladed disk and a shrouded-bladed disk were studied by introducing a special bladed-disk element and a special shrouded-blade element. Some features of the vibration of part-span-shrouded, bladed-disk rotor stages are discussed. The static deformation, thermal stress and gas bending effects on the blade vibration were presented previously.

  10. Evaluation of the solar disk sextant concept

    NASA Technical Reports Server (NTRS)

    Chiu, H.-Y.

    1984-01-01

    In this paper the viability of the solar disk sextant concept is evaluated, the optimum parameters required to carry out solar variability studies, which are the mission objectives, are derived. The experimental environment is first discussed, followed by the application of the finite Fourier transform definition (FFTD) to the detector array data. The requirements on the optical system are studied next. A computer program was carried out simulating solar edge data and FFTD. From this study, it is concluded that the required accuracy of measurement may be reached using currently available detector array technology, a focal ratio of the optical system in excess of 90, and an entrance aperture of 22 cm. The guidance error must be small enough to require no more than a correction rate of 0.1 arcsec/sec. All these conditions are well within current technology.

  11. Explosive magnetorotational instability in Keplerian disks

    NASA Astrophysics Data System (ADS)

    Shtemler, Yu.; Liverts, E.; Mond, M.

    2016-06-01

    Differentially rotating disks under the effect of axial magnetic field are prone to a nonlinear explosive magnetorotational instability (EMRI). The dynamic equations that govern the temporal evolution of the amplitudes of three weakly detuned resonantly interacting modes are derived. As distinct from exponential growth in the strict resonance triads, EMRI occurs due to the resonant interactions of an MRI mode with stable Alfvén-Coriolis and magnetosonic modes. Numerical solutions of the dynamic equations for amplitudes of a triad indicate that two types of perturbations behavior can be excited for resonance conditions: (i) EMRI which leads to infinite values of the three amplitudes within a finite time, and (ii) bounded irregular oscillations of all three amplitudes. Asymptotic explicit solutions of the dynamic equations are obtained for EMRI regimes and are shown to match the numerical solutions near the explosion time.

  12. Scattering from Thin Dielectric Disks

    NASA Technical Reports Server (NTRS)

    Levine, D. M.; Schneider, A.; Lang, R. H.; Carter, H. G.

    1984-01-01

    A solution was obtained for scattering from thin dielectric disks by approximating the currents induced inside the disk with the currents which would exist inside a dielectric slab of the same thickness, orientation and dielectric properties. This approximation reduces to an electrostatic approximation when the disk thickness, T, is small compared to the wavelength of the incident radiation and the approximation yields a conventional physical optics solution when the dimension, A, characteristic of the geometrical cross section of the disk (e.g., the diameter of a circular disk) is large compared to wavelength. When the ratio A/T is sufficiently large the disk will always be in one or the other of these regimes (T lambda or kA1. Consequently, when A/T is large this solution provides a conventional approximation for the scattered fields which can be applied at all frequencies. As a check on this conclusion, a comparison was made between the theoretical and measured radar cross section of thin dielectric disks. Agreement was found for thin disks with both large and small values of kA.

  13. Selected Papers on Protoplanetary Disks

    NASA Technical Reports Server (NTRS)

    Bell, K. R.; Cassen, P. M.; Wasson, J. T.; Woolum, D. S.; Klahr, H. H.; Henning, Th.

    2004-01-01

    Three papers present studies of thermal balances, dynamics, and electromagnetic spectra of protoplanetary disks, which comprise gas and dust orbiting young stars. One paper addresses the reprocessing, in a disk, of photons that originate in the disk itself in addition to photons that originate in the stellar object at the center. The shape of the disk is found to strongly affect the redistribution of energy. Another of the three papers reviews an increase in the optical luminosity of the young star FU Orionis. The increase began in the year 1936 and similar increases have since been observed in other stars. The paper summarizes astronomical, meteoric, and theoretical evidence that these increases are caused by increases in mass fluxes through the inner portions of the protoplanetary disks of these stars. The remaining paper presents a mathematical-modeling study of the structures of protostellar accretion disks, with emphasis on limits on disk flaring. Among the conclusions reached in the study are that (1) the radius at which a disk becomes shadowed from its central stellar object depends on radial mass flow and (2) most planet formation has occurred in environments unheated by stellar radiation.

  14. Disk Dispersal Around Young Stars

    NASA Technical Reports Server (NTRS)

    Hollenbach, David

    2004-01-01

    We first review the evidence pertaining to the lifetimes of planet-forming disks of gas and dust around young stars and discuss possible disk dispersal mechanisms: 1) viscous accretion of material onto the central source, 2) close stellar encounters, 3) stellar winds, and 4) photoevaporation caused by the heating of the disk surface by ultraviolet radiation. Photoevaporation is likely the most important dispersal mechanism for the outer regions of disks, and this talk focuses on the evaporation caused by the presence of a nearby, luminous star rather than the central star itself. We also focus on disks around low-mass stars like the Sun rather than high-mass stars, which we have treated previously. Stars often form in clusters and the ultraviolet flux from the most luminous star in the cluster can have a dramatic effect on the disk orbiting a nearby low-mass star. We apply our theoretical models to the evaporating protoplanetary disks (or "proplyds") in the Trapezium cluster in Orion, to the formation of gas giant planets like Jupiter around Sun-like stars in the Galaxy, and to the formation of Kuiper belts around low mass stars. We find a possible explanation for the differences between Neptune and Jupiter, and make a prediction concerning recent searches for giant planets in large clusters. We discuss recent models of the infrared spectra from gaseous disks around young stars.

  15. Ringed Accretion Disks: Equilibrium Configurations

    NASA Astrophysics Data System (ADS)

    Pugliese, D.; Stuchlík, Z.

    2015-12-01

    We investigate a model of a ringed accretion disk, made up by several rings rotating around a supermassive Kerr black hole attractor. Each toroid of the ringed disk is governed by the general relativity hydrodynamic Boyer condition of equilibrium configurations of rotating perfect fluids. Properties of the tori can then be determined by an appropriately defined effective potential reflecting the background Kerr geometry and the centrifugal effects. The ringed disks could be created in various regimes during the evolution of matter configurations around supermassive black holes. Therefore, both corotating and counterrotating rings have to be considered as being a constituent of the ringed disk. We provide constraints on the model parameters for the existence and stability of various ringed configurations and discuss occurrence of accretion onto the Kerr black hole and possible launching of jets from the ringed disk. We demonstrate that various ringed disks can be characterized by a maximum number of rings. We present also a perturbation analysis based on evolution of the oscillating components of the ringed disk. The dynamics of the unstable phases of the ringed disk evolution seems to be promising in relation to high-energy phenomena demonstrated in active galactic nuclei.

  16. Study of a flexible disk rotating close to a rigid rotating wall considering fluid inertia effects

    NASA Astrophysics Data System (ADS)

    Gad, Abdelrasoul M. M.; Rhim, Yoon Chul

    2008-11-01

    The present study is a numerical simulation about the dynamics of a flexible disk coupled to thin air film and rotating close to a rigid rotating wall. The idea of a flexible disk rotating in a close proximity of a rigid rotating wall is introduced and studied with two new types of flat stabilizers, co-rotating and counter-rotating flat stabilizers, besides the well-known fixed-stabilizer type which has been studied extensively in earlier works. In the present study, the flexible disk is modeled using linear plate theory and the air flow between the flexible disk and the rigid wall is modeled using Navier-Stokes and continuity equations. The flow equations are discretized using cell centered finite volume method (FVM) and solved numerically with the SIMPLE algorithm, while the spatial terms in the disk model are discretized using finite difference method (FDM) and time integration is performed using fourth-order Runge-Kutta method. The effect of inertia and coriollis forces on the disk displacement and air-film pressure is studied, also the dependence of these forces on the rotation speed, initial gap size and inlet-hole radius is investigated. A transient numerical code is developed to compare the stability boundaries for the different types of flat stabilizer at a wide range of circumferential mode numbers. The numerical results showed an improved stability of the flexible disk when rotating close to a counter-rotating flat stabilizer compared with co-rotating and fixed flat stabilizers.

  17. Workshop on Physics of Accretion Disks Around Compact and Young Stars

    NASA Technical Reports Server (NTRS)

    Liang, E (Editor); Stepinski, T. F. (Editor)

    1995-01-01

    The purpose of the two-day Workshop on Physics of Accretion Disks Around Compact and Young Stars was to bring together workers on accretion disks in the western Gulf region (Texas and Louisiana). Part 2 presents the workshop program, a list of poster presentations, and a list of workshop participants. Accretion disks are believed to surround many stars. Some of these disks form around compact stars, such as white dwarfs, neutron stars, or black holes that are members of binary systems and reveal themselves as a power source, especially in the x-ray and gamma regions of the spectrum. On the other hand, protostellar disks are believed to be accretion disks associated with young, pre-main-sequence stars and manifest themselves mostly in infrared and radio observations. These disks are considered to be a natural outcome of the star formation process. The focus of this workshop included theory and observations relevant to accretion disks around compact objects and newly forming stars, with the primary purpose of bringing the two communities together for intellectual cross-fertilization. The nature of the workshop was exploratory, to see how much interaction is possible between distinct communities and to better realize the local potential in this subject. A critical workshop activity was identification and documentation of key issues that are of mutual interest to both communities.

  18. Debris Disks and Hidden Planets

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2008-01-01

    When a planet orbits inside a debris disk like the disk around Vega or Beta Pictoris, the planet may be invisible, but the patterns it creates in the disk may give it away. Observing and decoding these patterns may be the only way we can detect exo-Neptunes orbiting more than 20 AU from their stars, and the only way we can spot planets in systems undergoing the late stages of planet formation. Fortunately, every few months, a new image of a debris disk appears with curious structures begging for explanation. I'll describe some new ideas in the theory of these planet-disk interactions and provide a buyers guide to the latest models (and the planets they predict).

  19. Tracing characteristic perturbations resulting from Planet-Disk and Binary-Disk interaction in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Ruge, Jan Philipp; Wolf, Sebastian; Uribe, Ana; Demidova, Tatiana; Klahr, Hubert; Grinin, Vladimir

    2013-07-01

    The perturbation by an additional, gravitating component (planet, binary star) within a protoplanetary disk induces characteristic large-scale structures in the disk density profile. We investigate the observability of these perturbations. On the basis of a large number of (M)HD and SPH simulations, we calculate synthetic scattered and polarized light images as well as thermal re-emission maps of these models and predict the observational results for different instruments from the optical to the (sub)mm wavelength range with a special focus on ALMA. In the first study (A) (Ruge et al., 2013a,c) we investigate the observability of the planet-disk interaction for different star-disk-planet configurations. We predict that ALMA is able to observe planet-induced gaps around stars of various types and for a large range of disk masses. Besides this, we find that ALMA can trace small, local perturbations indicating zonal flows in the disk. The detectability of gaps in scattered light is limited to a range of total disk masses between 1e-4 M_sun and 1e-6 M_sun. Gap detections in both wavelength ranges are feasible for M_disk ~ 1e-4 M_sun. In our second study (B) (Ruge et al. 2013b) we investigate the observability of perturbations in young circumbinary disks for several orbital elements of the binary system. We find that ALMA will allow one to trace characteristic AU-sized spiral arm features in disks in face-on orientation and also to detect binary-induced perturbations in the edge-on brightness profiles. We find that the technique of differential polarimetry offers the potential for significantly clearer detections of these disk structures than imaging in scattered light alone.

  20. Multiwavelength search for protoplanetary disks

    NASA Technical Reports Server (NTRS)

    Neuhaeuser, Ralph; Schmidt-Kaler, Theodor

    1994-01-01

    Infrared emission of circumstellar dust was observed for almost one hundred T Tauri stars. This dust is interpreted to be part of a protoplanetary disk orbiting the central star. T Tauri stars are young stellar objects and evolve into solar type stars. Planets are believed to form in these disks. The spectral energy distribution of a disk depends on its temperature profile. Different disk regions emit at different wavelengths. The disk-star boundary layer is hot and emits H(alpha) radiation. Inner disk regions at around 1 AU with a temperature of a few hundred Kelvin can be probed in near infrared wavelength regimes. Outer disk regions at around 100 AU distance from the star are colder and emit far infrared and sub-millimeter radiation. Also, X-ray emission from the stellar surface can reveal information on disk properties. Emission from the stellar surface and the boundary layer may be shielded by circumstellar gas and dust. T Tauri stars with low H(alpha) emission, i.e. no boundary layer, show stronger X-ray emission than classical T Tauri stars, because the inner disk regions of weak emission-line T Tauri stars may be clear of material. In this paper, first ROSAT all sky survey results on the X-ray emission of T Tauri stars and correlations between X-ray luminosity and properties of T Tauri disks are presented. Due to atmospheric absorption, X-ray and most infrared observations cannot be carried out on Earth, but from Earth orbiting satellites (e.g. IRAS, ROSAT, ISO) or from lunar based observatories, which would have special advantages such as a stable environment.

  1. Berkeley Disk Resource Manager

    Energy Science and Technology Software Center (ESTSC)

    2004-02-27

    The Berkeley Disk Resource Manager (B-DRM) is a middleware component whose function is to provide dynamic space allocation and file management of a shared disk system on the Grid. It provides space allocation and dynamic information on storage availability for the planning and execution of Grid jobs. The B-DRM manages two types of resources: space and files. Vi1en managing space, the B-DRM allocates space to the requesting client based on a default space quota, Thenmore » managing files, the B-DRM allocates space for files, invokes file transfer services to move files into the space, pins files for a certain lifetime, releases files upon the client’s request, and uses file replacement policies to optimize the use of the shared space. The B-DRM is designed to provide effective sharing of files, by monitoring the activity of shared files, and making dynamic decisions on which files to replace when space is needed. In addition, the B-DRM performs automatic garbage collection of unused files when space is needed by removing selected files that were released by the client or whose lifetime has expired. The BDRM supports requests to get multiple files in a single call, manages a queue of the requested files, brings in as many files as the space quota permits, and continues to reuse the space when files are released to stream files to the client until the entire request is satisfied. Similarly, the B-DRM supports requests to put multiple files into its space, streaming files into the allocated space and reusing the space if necessary.« less

  2. RAID 7 disk array

    NASA Technical Reports Server (NTRS)

    Stout, Lloyd

    1993-01-01

    Each RAID level reflects a different design architecture. Associated with each is a backdrop of imposed limitations, as well as possibilities which may be exploited within the architectural constraints of that level. There are three unique features that differentiate RAID 7 from all other levels. RAID 7 is asynchronous with respect to usage of I/O data paths. Each I/O drive (includes all data and one parity drives) as well as each host interface (there may be multiple host interfaces) has independent control and data paths. This means that each can be accessed completely, independently, of the other. This is facilitated by a separate device cache for each device/interface as well. RAID 7 is asynchronous with respect to device hierarchy and data bus utilization. Each drive and each interface is connected to a high speed data bus controlled by the embedded operating system to make independent transfers to and from central cache. RAID 7 is asynchronous with respect to the operation of an embedded real time process oriented operating system. This means that exclusive and independent of the host, or multiple host paths, the embedded OS manages all I/O transfers asynchronously across the data and parity drives. A key factor to consider is that of the RAID 7's ability to anticipate and match host I/O usage patterns. This yields the following benefits over RAID's built around micro-code based architectures. RAID 7 appears to the host as a normally connected Big Fast Disk (BFD). RAID 7 appears, from the perspective of the individual disk devices, to minimize the total number of accesses and optimize read/write transfer requests. RAID 7 smoothly integrates the random demands of independent users with the principles of spatial and temporal locality. This optimizes small, large, and time sequenced I/O requests which results in users having an I/O performance which approaches performance to that of main memory.

  3. Berkeley Disk Resource Manager

    SciTech Connect

    Shoshani, Arie; Sim, Alex; Gu, Junmin

    2004-02-27

    The Berkeley Disk Resource Manager (B-DRM) is a middleware component whose function is to provide dynamic space allocation and file management of a shared disk system on the Grid. It provides space allocation and dynamic information on storage availability for the planning and execution of Grid jobs. The B-DRM manages two types of resources: space and files. Vi1en managing space, the B-DRM allocates space to the requesting client based on a default space quota, Then managing files, the B-DRM allocates space for files, invokes file transfer services to move files into the space, pins files for a certain lifetime, releases files upon the client’s request, and uses file replacement policies to optimize the use of the shared space. The B-DRM is designed to provide effective sharing of files, by monitoring the activity of shared files, and making dynamic decisions on which files to replace when space is needed. In addition, the B-DRM performs automatic garbage collection of unused files when space is needed by removing selected files that were released by the client or whose lifetime has expired. The BDRM supports requests to get multiple files in a single call, manages a queue of the requested files, brings in as many files as the space quota permits, and continues to reuse the space when files are released to stream files to the client until the entire request is satisfied. Similarly, the B-DRM supports requests to put multiple files into its space, streaming files into the allocated space and reusing the space if necessary.

  4. Cavities in inner disks: the GM Aurigae case

    NASA Astrophysics Data System (ADS)

    Dutrey, A.; Guilloteau, S.; Piétu, V.; Chapillon, E.; Gueth, F.; Henning, T.; Launhardt, R.; Pavlyuchenkov, Y.; Schreyer, K.; Semenov, D.

    2008-11-01

    Context: Recent modeling based on unresolved infrared observations of the spectral energy distribution (SED) of GM Aurigae suggests that the inner disk of this single TTauri star is truncated at an inner radius of 25 AU. Aims: We attempt to find evidence of this inner hole in the gas distribution, using spectroscopy with high angular resolution. Methods: Using the IRAM array, we obtained high angular resolution ( 1.5”) observations with a high S/N per channel of the 13CO J=2{-}1 and C18O J=2{-}1 and of the 13CO J=1{-}0 lines. A standard parametric disk model is used to fit the line data in the Fourier-plane and to derive the CO disk properties. Our measurement is based on a detailed analysis of the spectroscopic profile from the CO disk rotating in Keplerian velocity. The millimeter continuum, tracing the dust, is also analyzed. Results: We detect an inner cavity of radius 19 ± 4 AU at the 4.5σ level. The hole manifests itself by a lack of emission beyond the (projected) Keplerian speed at the inner radius. We also constrain the temperature gradient in the disk. Conclusions: Our data reveal the existence of an inner hole in GM Aur gas disk. Its origin remains unclear, but can be linked to planet formation or to a low mass stellar companion orbiting close to the central star ( 5-15 AU). The frequent finding of inner cavities suggests that either binarity is the most common scenario of star formation in Taurus or that giant planet formation starts early. Based on observations carried out with the IRAM Plateau de Bure Interferometer. IRAM is supported by INSU/CNRS (France), MPG (Germany) and IGN (Spain).

  5. Accretion of solid materials onto circumplanetary disks from protoplanetary disks

    SciTech Connect

    Tanigawa, Takayuki; Maruta, Akito; Machida, Masahiro N.

    2014-04-01

    We investigate the accretion of solid materials onto circumplanetary disks from heliocentric orbits rotating in protoplanetary disks, which is a key process for the formation of regular satellite systems. In the late stage of the gas-capturing phase of giant planet formation, the accreting gas from protoplanetary disks forms circumplanetary disks. Since the accretion flow toward the circumplanetary disks affects the particle motion through gas drag force, we use hydrodynamic simulation data for the gas drag term to calculate the motion of solid materials. We consider a wide range of size for the solid particles (10{sup –2}-10{sup 6} m), and find that the accretion efficiency of the solid particles peaks around 10 m sized particles because energy dissipation of drag with circum-planetary disk gas in this size regime is most effective. The efficiency for particles larger than 10 m becomes lower because gas drag becomes less effective. For particles smaller than 10 m, the efficiency is lower because the particles are strongly coupled with the background gas flow, which prevents particles from accretion. We also find that the distance from the planet where the particles are captured by the circumplanetary disks is in a narrow range and well described as a function of the particle size.

  6. Low-state disks and low-beta disks

    NASA Technical Reports Server (NTRS)

    Mineshige, Shin; Kusnose, Masaaki; Matsumoto, Ryoji

    1995-01-01

    Stellar black hole candidates (BHCs) exhibit bimodal spectral states. We calculate nonthermal disk spectra, demonstrating that a large photon index (alpha (sub x) approximately 2-3) observed in the soft (high) state is due to a copious soft photon supply, whereas soft photon starvation leads to a smaller index (alpha (sub x) approximately 1.5-2) in the hard (low) state. Thus, the absence of the soft component flux in the low state cannot be due to obscuration. A possible disk configuration during the low state is discussed. We proposed that a low-state disk may be a low-beta disk in which magnetic pressure may exceed gas pressure becuase of the suppression of field escape by a strong shear. As a result, disk material will take the form of blobs constricted by mainly toroidal magnetic fields. Fields are dissipated mainly by occasional reconnection events with a huge energy release. This will account for large-amplitude, aperiodic X-ray variations (flickering) and high-energy radiation with small alpha(sub x) from hard state BHCs and possibly from active galactic nuclei. Further, we propose a hysteretic relation between the mass-flow rate and plasma-beta, a ratio of gas pressure to magnetic pressure, for the spectral evolution of transient BHCs. The disk is in the low-beta state in quiescence and early rise. The low-beta disk is optically thin and affected by advection. A hard-to-soft transition occurs before the peak luminosity, since there is no advection-dominated branch at higher luminosities. An optically thick, high-beta disk appears at small radii. In the decay phase of the light curve, the standard-type disk becomes effectively optically thin, when a soft-hard transition is triggered. High-beta plasmas in the main body shrink to form minute blobs, and low-beta coronal plasma fills interblob space.

  7. KECK ADAPTIVE OPTICS OBSERVATIONS OF THE PROTOSTELLAR DISK AROUND RADIO SOURCE I IN THE ORION KLEINMANN-LOW NEBULA

    SciTech Connect

    Sitarski, Breann N.; Morris, Mark R.; Becklin, E. E.; Ghez, Andrea M.; Lu, Jessica R.; Duchene, Gaspard; Stolte, Andrea; Zinnecker, Hans

    2013-06-20

    We have made the first detection of a near-infrared counterpart associated with the disk around Radio Source ''I'', a massive protostar in the Kleinmann-Low nebula in Orion, using imaging with laser guide star adaptive optics on the Keck II telescope. The infrared emission is evident in images acquired using L' (3.8 {mu}m) and Ms (4.7 {mu}m) filters and is not detectable at K' (2.1 {mu}m). The observed morphology strongly suggests that we are seeing some combination of scattered and thermal light emanating from the disk. The disk is also manifest in the L'/Ms flux ratio image. We interpret the near-infrared emission as the illuminated surface of a nearly edge-on disk, oriented so that only the northern face is visible; the opposite surface remains hidden by the disk. We do not see infrared radiation associated directly with the star proposed to be associated with Source ''I''. The data also suggest that there is a cavity above and below the disk that is oriented perpendicular to the disk and is sculpted by the known, strong outflow from the inner disk of Source I. We compare our data to models of a protostar with a surrounding disk, envelope, and wind-blown cavity in order to elucidate the nature of the disk around Radio Source I.

  8. Rheumatic manifestations of hematologic disorders.

    PubMed

    Aviña-Zubieta, J A; Galindo-Rodriguez, G; Lavalle, C

    1998-01-01

    A review of the literature during the past year on rheumatic manifestations in hematologic diseases supports the idea that 80% of the hemorrhage in hemophilia occurs within the joints, with knees, elbows, and ankles being the most affected joints in adults. In contrast, the ankle is the target joint in children. Septic arthritis in hemophilic patients is becoming more important due to the advent of HIV infection. Radioactive synoviorthesis in hemarthrosis has the same rate of success as surgical synovectomy, but with far lower costs. A new study documents the association of arthritis and vasculitis in patients with myelodysplasic syndromes and lymphoproliferative disorders. An increased incidence of scoliosis in patients with beta-thalassemia has been noted. Finally, the effects of bone marrow transplantation in patients with previous autoimmune diseases is reviewed. Progression of rheumatoid arthritis after bone marrow transplantation is documented in a patient with 13 years of follow-up. Hematologic disorders in rheumatic diseases are not the topic of this review. PMID:9448995

  9. Clinical Manifestations of Spontaneous Pneumomediastinum

    PubMed Central

    Park, Soo Jin; Park, Ji Ye; Jung, Joonho; Park, Seong Yong

    2016-01-01

    Background Spontaneous pneumomediastinum (SPM) is an uncommon disorder with only a few reported clinical studies. The goals of this study were to investigate the clinical manifestations and the natural course of SPM, as well as examine the current available treatment options for SPM. Methods We retrospectively reviewed 91 patients diagnosed with SPM between January 2008 and June 2015. Results The mean age of the patients was 22.7±13.2 years, and 67 (73.6%) were male. Chest pain (58, 37.2%) was the predominant symptom. The most frequent precipitating factor before developing SPM was a cough (15.4%), but the majority of patients (51, 56.0%) had no precipitating factors. Chest X-ray was diagnostic in 44 patients (48.4%), and chest computed tomography (CT) showed mediastinal air in all cases. Esophagography (10, 11.0%), esophagoduodenoscopy (1, 1.1%), and bronchoscopy (5, 5.5%) were performed selectively due to clinical suspicion, but no abnormal findings that implicated organ injury were documented. Twelve patients (13.2%) were discharged after a visit to the emergency room, and the others were admitted and received conservative treatment. The mean length of hospital stay was 3.0±1.6 days. There were no complications related to SPM except for recurrence in 2 patients (2.2%). Conclusion SPM responds well to conservative treatment and follows a benign natural course. Hospitalization and aggressive treatment can be performed in selective cases. PMID:27525238

  10. Skin manifestations of drug allergy

    PubMed Central

    Ardern-Jones, Michael R; Friedmann, Peter S

    2011-01-01

    Cutaneous adverse drug reactions range from mild to severe and from those localized only to skin to those associated with systemic disease. It is important to distinguish features of cutaneous drug reactions which help classify the underlying mechanism and likely prognosis as both of these influence management decisions, some of which necessarily have to be taken rapidly. Severe cutaneous reactions are generally T cell-mediated, yet this immunological process is frequently poorly understood and principles for identification of the culprit drug are different to those of IgE mediated allergic reactions. Furthermore, intervention in severe skin manifestations of drug allergy is frequently necessary. However, a substantial literature reports on success or otherwise of glucocorticoids, cyclophsphamide, ciclosporin, intravenous immunoglobulin and anti-tumour necrosis factor therapy for the treatment of toxic epidermal necrolysis without clear consensus. As well as reviewing the recommended supportive measures and evidence base for interventions, this review aims to provide a mechanistic overview relating to a proposed clinical classification to assist the assessment and management of these complex patients. PMID:21480947

  11. Cutaneous manifestations of genitourinary malignancy.

    PubMed

    Raghavan, Derek

    2016-06-01

    Genitourinary cancers are associated with a range of cutaneous syndromes, which can reflect direct metastatic spread, non-metastatic manifestations of malignancy or the consequences of treatment. More than 220,000 new cases of prostate cancer occur each year in the United States, and thus the associations with cutaneous involvement are quite well documented-rare metastatic spread, vasculitic and hemorrhagic syndromes. Cancers of the bladder and kidney may be associated with direct cutaneous metastases, vasculitic syndromes, hereditary leiomyomatosis, and other familial syndromes. Testicular cancer occasionally metastasizes to the skin but more commonly is associated with the dysplastic nevus (multiple atypical nevus) syndrome. A structured approach to history-taking, examination, and investigation is essential for optimal management, especially when these syndromes precede the diagnosis of a known malignancy. A brief review of the more common iatrogenic cutaneous complications is provided, and includes Raynaud's phenomenon, purpura, rash, hand-foot syndrome, the consequences of marrow failure, and bleomycin-induced pigmentation. PMID:27178687

  12. Dermatologic manifestations of Lyme disease.

    PubMed

    Berger, B W

    1989-01-01

    Erythema migrams (EM), the distinctive cutaneous lesion of Lyme disease, has a variable clinical appearance, but at some point presents as a centrifugally expanding, usually erythematous, annular patch. Of 237 patients with this condition, 201 (85%) were examined initially from May through September. Thirty-four (14%) remembered having been bitten by a deer tick. The median interval from the bite to the appearance of EM was 9 days (range, 1-36 days). Forty-one (17%) of the patients had multiple EM lesions. Of the 237 patients, 128 (54%) manifested major extracutaneous signs and symptoms. Although EM also has a variable histologic picture, the presence of a deep and superficial perivascular and interstitial lymphohistiocytic infiltrate containing plasma cells is diagnostic. Spirochetes can be demonstrated with Warthin-Starry staining in approximately 40% of the biopsy specimens. Concomitant cutaneous lesions appeared on some patients before and during antibiotic therapy. Nine patients with serologic evidence of Borrelia burgdorferi infection had cutaneous lesions other than EM, including granuloma annulare (three), erythema nodosum (two), papular urticaria (two), Henoch-Schönlein-like purpura (one), and morphea (one). Whether these entities are cutaneous markers of Lyme disease or are coincidental findings is yet to be determined. PMID:2814169

  13. Extracardiac manifestations of bacterial endocarditis.

    PubMed

    Heffner, J E

    1979-08-01

    Bacterial endocarditis is an elusive disease that challenges clinicians' diagnostic capabilities. Because it can present with various combinations of extravalvular signs and symptoms, the underlying primary disease can go unnoticed.A review of the various extracardiac manifestations of bacterial endocarditis suggests three main patterns by which the valvular infection can be obscured. (1) A major clinical event may be so dramatic that subtle evidence of endocarditis is overlooked. The rupture of a mycotic aneurysm may simulate a subarachnoid hemorrhage from a congenital aneurysm. (2) The symptoms of bacterial endocarditis may be constitutional complaints easily attributable to a routine, trivial illness. Symptoms of low-grade fever, myalgias, back pain and anorexia may mimic a viral syndrome. (3) Endocarditis poses a difficult diagnostic dilemma when it generates constellations of findings that are classic for other disorders. Complaints of arthritis and arthralgias accompanied by hematuria and antinuclear antibody may suggest systemic lupus erythematosus; a renal biopsy study showing diffuse proliferative glomerulonephritis may support this diagnosis. The combination of fever, petechiae, altered mental status, thrombocytopenia, azotemia and anemia may promote the diagnosis of thrombotic thrombocytopenic purpura. When the protean guises of bacterial endocarditis create these clinical difficulties, errors in diagnosis occur and appropriate therapy is delayed. Keen awareness of the varied disease presentations will improve success in managing endocarditis by fostering rapid diagnosis and prompt therapy. PMID:516715

  14. Ocular manifestations of frontonasal dysplasia.

    PubMed

    Roarty, J D; Pron, G E; Siegel-Bartelt, J; Posnick, J C; Buncic, J R

    1994-01-01

    The ophthalmologic findings associated with frontonasal dysplasia have not been defined previously in a large series of untreated children. We reviewed the ophthalmic manifestations of a series of patients with frontonasal dysplasia who were seen as part of their craniofacial evaluation. All had undergone a complete ophthalmologic examination before any manipulation of either the orbits or the soft tissues of the orbital contents. From 1986 to 1991, 23 patients with frontonasal dysplasia were seen; ophthalmologic abnormalities were found in 20 (87 percent). Abnormalities included significant refractive errors, strabismus, nystagmus, and eyelid ptosis. Three patients had amblyopia, a treatable cause of visual loss, from strabismus or anisometropia. Ten eyes in seven patients (30 percent) had severe structural anomalies, such as optic nerve hypoplasia, optic nerve colobomas, microphthalmia, cataract, corneal dermoid, or inflammatory retinopathy, that resulted in an acuity of 20/100 or worse. The high incidence of ocular abnormalities indicates that early assessment by an ophthalmologist should be part of the initial evaluation of patients with frontonasal dysplasia to detect treatable visual or ocular problems. PMID:8278482

  15. [EEG manifestations in metabolic encephalopathy].

    PubMed

    Lin, Chou-Ching K

    2005-09-01

    Normal brain function depends on normal neuronal metabolism, which is closely related to systemic homeostasis of metabolites, such as glucose, electrolytes, amino acids and ammonia. "Metabolic encephalopathy" indicates diffuse brain dysfunction caused by various systemic derangements. Electroencephalogram (EEG) is widely used to evaluate metabolic encephalopathy since 1937, when Berger first observed slow brain activity induced by hypoglycemia. EEG is most useful in differentiating organic from psychiatric conditions, identifying epileptogenicity, and providing information about the degree of cortical or subcortical dysfunction. In metabolic encephalopathy, EEG evolution generally correlates well with the severity of encephalopathy. However, EEG has little specificity in differentiating etiologies in metabolic encephalopathy. For example, though triphasic waves are most frequently mentioned in hepatic encephalopathy, they can also be seen in uremic encephalopathy, or even in aged psychiatric patients treated with lithium. Spike-and-waves may appear in hyper- or hypo-glycemia, uremic encephalopathy, or vitamin deficiencies, etc. Common principles of EEG changes in metabolic encephalopathy are (1) varied degrees of slowing, (2) assorted mixtures of epileptic discharge, (3) high incidence of triphasic waves, and (4), as a rule, reversibility after treatment of underlying causes. There are some exceptions to the above descriptions in specific metabolic disorders and EEG manifestations are highly individualized. PMID:16252619

  16. Comparison of Multi Disk Exponential Gas Distribution vs. Single Disk

    NASA Astrophysics Data System (ADS)

    Rao, Erica; O'Brien, James

    2013-04-01

    In fitting galactic rotation curves to data, most standard theories make use of a single exponential disk approximation of the gas distribution to account for the HI synthesis data observed at various radio telescope facilities. We take a sample of surface brightness profiles from The HI Nearby Galaxy Survey (THINGS), and apply both single disk exponentials and Multi-Disk exponentials, and use these various models to see how the modelling procedure changes the Newtonian prediction of the mass of the galaxy. Since the missing mass problem has not been fully explained in large spiral galaxies, different modelling procedures could account for some of the missing matter.

  17. Protoplanetary and Debris Disk Morphologies

    NASA Astrophysics Data System (ADS)

    Lomax, Jamie R.; Wisniewski, John P.; Grady, Carol A.; McElwain, Michael W.; Hashimoto, Jun; Donaldson, Jessica; Debes, John H.; Malumuth, Eliot; Roberge, Aki; Weinberger, Alycia J.; SEEDS Team

    2016-01-01

    The types of planets that form around other stars are highly dependent on their natal disk conditions. Therefore, the composition, morphology, and distribution of material in protoplanetary and debris disks are important for planet formation. Here we present the results of studies of two disk systems: AB Aur and AU Mic.The circumstellar disk around the Herbig Ae star AB Aur has many interesting features, including spirals, asymmetries, and non-uniformities. However, comparatively little is known about the envelope surrounding the system. Recent work by Tang et al (2012) has suggested that the observed spiral armss may not in fact be in the disk, but instead are due to areas of increased density in the envelope and projection effects. Using Monte Carlo modeling, we find that it is unlikely that the envelope holds enough material to be responsible for such features and that it is more plausible that they form from disk material. Given the likelihood that gravitational perturbations from planets cause the observed spiral morphology, we use archival H band observations of AB Aur with a baseline of 5.5 years to determine the locations of possible planets.The AU Mic debris disk also has many interesting morphological features. Because its disk is edge on, the system is an ideal candidate for color studies using coronagraphic spectroscopy. Spectra of the system were taken by placing a HST/STIS long slit parallel to and overlapping the disk while blocking out the central star with an occulting fiducial bar. Color gradients may reveal the chemical processing that is occuring within the disk. In addition, it may trace the potential composition and architecture of any planetary bodies in the system because collisional break up of planetesimals produces the observed dust in the system. We present the resulting optical reflected spectra (5200 to 10,200 angstroms) from this procedure at several disk locations. We find that the disk is bluest at the innermost locations of the

  18. 19 CFR 122.75 - Complete manifest.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... Manifest Requirements for Passengers, Crew Members, and Non-Crew Members Onboard Commercial Aircraft... of the cargo carried on aircraft No. ____, Flight No. ____ cleared direct for ____, on ____...

  19. 19 CFR 122.75 - Complete manifest.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... Manifest Requirements for Passengers, Crew Members, and Non-Crew Members Onboard Commercial Aircraft... of the cargo carried on aircraft No. ____, Flight No. ____ cleared direct for ____, on ____...

  20. 19 CFR 122.75 - Complete manifest.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... Manifest Requirements for Passengers, Crew Members, and Non-Crew Members Onboard Commercial Aircraft... of the cargo carried on aircraft No. ____, Flight No. ____ cleared direct for ____, on ____...

  1. 19 CFR 122.75 - Complete manifest.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... Manifest Requirements for Passengers, Crew Members, and Non-Crew Members Onboard Commercial Aircraft... of the cargo carried on aircraft No. ____, Flight No. ____ cleared direct for ____, on ____...

  2. Ocular manifestations of genetic skin disorders.

    PubMed

    Jen, Melinda; Nallasamy, Sudha

    2016-01-01

    Genetic skin diseases, or genodermatoses, often have extracutaneous manifestations. Ocular manifestations in particular can have significant clinical implications, like blindness. Other manifestations, such as the corneal opacities that occur in X-linked ichthyosis, are asymptomatic but characteristic of a particular genodermatosis. Ophthalmologic examination can aid in diagnosis when characteristic findings are seen. The genodermatoses with ocular manifestations will be reviewed, but neurocutaneous, syndromes, genetic pigmentary disorders, and genetic metabolic diseases are not included because they are covered elsewhere in this issue. PMID:26903188

  3. A study of the effects of disk flexibility on the rotordynamics of the space shuttle main engine turbo-pumps

    NASA Technical Reports Server (NTRS)

    Flowers, George T.

    1989-01-01

    Rotor dynamical analyses are typically performed using rigid disk models. Studies of rotor models in which the effects of disk flexibility were included indicate that is may be an important effect for many systems. This issue is addressed with respect to the Space Shuttle Main Engine high pressure turbo-pumps. Finite element analyses have been performed for a simplified free-free flexible disk rotor model and the modes and frequencies compared to those of a rigid disk model. The simple model was then extended to a more sophisticated HPTOP rotor model and similar results were observed. Equations were developed that are suitable for modifying the current rotordynamical analysis program to account for disk flexibility. Some conclusions are drawn from the results of this work as to the importance of disk flexibility on the HPTOP rotordynamics and some recommendations are given for follow-up research in this area.

  4. Photoevaporating Disks Around Young Stars

    NASA Technical Reports Server (NTRS)

    Hollenbach, David

    2004-01-01

    Ultraviolet radiation from the central star or from a nearby massive star heats the surfaces of protoplanetary disks and causes the outer, less gravitationally bound part of the disks, to photoevaporate into interstellar space. Photoevaporation is likely the most important dispersal mechanism for the outer regions of disks. We focus in this talk on disks around low-mass stars like the Sun rather than high-mass stars, which we have treated previously. Stars often form in clusters and the ultraviolet flux from the most luminous star in the cluster can have a dramatic effect on the disk orbiting a nearby low-mass star. We apply our theoretical models to the evaporating protoplanetary disks (or "proplyds") in the Trapezium cluster in Orion, to the formation of gas giant planets like Jupiter around Sun-like stars in the Galaxy, and to the formation of Kuiper belts around low mass stars. We discuss recent models of the effects of the radiation from the central low mass star including both the predicted infrared spectra from the heated disks as well as preliminary results on the photoevaporation rates.

  5. Heating and Cooling Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Turner, Neal

    Many of the disks of gas and dust orbiting young Sun-like stars produce mid-infrared emission from water and other oxygen- and carbon-bearing molecules, as discovered in the last few years using the Spitzer Space Telescope. The emission reveals the temperatures, columns and chemical composition of the gas in the disk atmosphere within 2 AU of the star, directly overlying the region where the planets form. Better understanding of the processes governing the line emission is vital for converting this new class of measurements into information about the planets' raw ingredients. We propose to combine MHD models of the turbulence driving the disk accretion flows, with a thermal-chemical model of the disk atmospheres, to predict emergent spectra that will capture the dynamics, heating, and chemical composition. By comparing the predicted and observed spectra we can determine the strength of the turbulence that heats and mixes the gas, and test ideas about the conditions in the disk interior. We will investigate the coupling of the turbulence to the thermal and chemical evolution, seek to locate the line emission's power source, gauge the rate at which the atmosphere and interior exchange material, and obtain new independent measures of the disk mass accretion rates. These efforts will help infrared spectroscopy of protostellar disks reach its full potential as a diagnostic of the environments in which planets form.

  6. Magnetically Torqued Thin Accretion Disks

    NASA Astrophysics Data System (ADS)

    Kluźniak, W.; Rappaport, S.

    2007-12-01

    We compute the properties of a geometrically thin, steady accretion disk surrounding a central rotating, magnetized star. The magnetosphere is assumed to entrain the disk over a wide range of radii. The model is simplified in that we adopt two (alternate) ad hoc, but plausible, expressions for the azimuthal component of the magnetic field as a function of radial distance. We find a solution for the angular velocity profile tending to corotation close to the central star and smoothly matching a Keplerian curve at a radius where the viscous stress vanishes. The value of this ``transition'' radius is nearly the same for both of our adopted B-field models. We then solve analytically for the torques on the central star and for the disk luminosity due to gravity and magnetic torques. When expressed in a dimensionless form, the resulting quantities depend on one parameter alone, the ratio of the transition radius to the corotation radius. For rapid rotators, the accretion disk may be powered mostly by spin-down of the central star. These results are independent of the viscosity prescription in the disk. We also solve for the disk structure for the special case of an optically thick alpha disk. Our results are applicable to a range of astrophysical systems including accreting neutron stars, intermediate polar cataclysmic variables, and T Tauri systems.

  7. DiskJockey: Protoplanetary disk modeling for dynamical mass derivation

    NASA Astrophysics Data System (ADS)

    Czekala, Ian

    2016-03-01

    DiskJockey derives dynamical masses for T Tauri stars using the Keplerian motion of their circumstellar disks, applied to radio interferometric data from the Atacama Large Millimeter Array (ALMA) and the Submillimeter Array (SMA). The package relies on RADMC-3D (ascl:1202.015) to perform the radiative transfer of the disk model. DiskJockey is designed to work in a parallel environment where the calculations for each frequency channel can be distributed to independent processors. Due to the computationally expensive nature of the radiative synthesis, fitting sizable datasets (e.g., SMA and ALMA) will require a substantial amount of CPU cores to explore a posterior distribution in a reasonable timeframe.

  8. Shoulder manifestations of diabetes mellitus.

    PubMed

    Garcilazo, Cintia; Cavallasca, Javier A; Musuruana, Jorge L

    2010-09-01

    The musculoskeletal system can be affected by diabetes in a number of ways. The shoulder is one of the frequently affected sites. One of the rheumatic conditions caused by diabetes is frozen shoulder (adhesive capsulitis), which is characterized by pain and severe limited active and passive range of motion of the glenohumeral joint, particularly external rotation. This disorder has a clinical diagnosis and the treatment is based on physiotherapy, non-steroidal anti-inflammatory drugs (NSAIDs), corticosteroid injections and, in refractory cases, surgical resolution. As with adhesive capsulitis, calcific periarthritis of the shoulder causes pain and limited joint mobility, although usually it has a better prognosis than frozen shoulder. Reflex sympathetic dystrophy, also known as shoulder-hand syndrome, is a painful syndrome associated with vasomotor and sudomotor changes in the affected member. Diabetic amyotrophy usually affects the peripheral nerves of lower limbs. However, when symptoms involve the shoulder girdle, it must be considered in the differential diagnosis of shoulder painful conditions. Osteoarthritis is the most common rheumatic condition. There are many risk factors for shoulder osteoarthritis including age, genetics, sex, weight, joint infection, history of shoulder dislocation, and previous injury, in older age patients, diabetes is a risk factor for shoulder OA. Treatment options include acetaminophen, NSAIDs, short term opiate, glucosamine and chondroitin. Corticosteroid injections and/or injections of hyaluronans could also be considered. Patients with continued disabling pain that is not responsive to conservative measures may require surgical referral. The present review will focus on practice points of view about shoulder manifestations in patients with diabetes. PMID:20701586

  9. Future hard disk drive systems

    NASA Astrophysics Data System (ADS)

    Wood, Roger

    2009-03-01

    This paper briefly reviews the evolution of today's hard disk drive with the additional intention of orienting the reader to the overall mechanical and electrical architecture. The modern hard disk drive is a miracle of storage capacity and function together with remarkable economy of design. This paper presents a personal view of future customer requirements and the anticipated design evolution of the components. There are critical decisions and great challenges ahead for the key technologies of heads, media, head-disk interface, mechanics, and electronics.

  10. Gravitational asymmetries in gaseous disks.

    NASA Astrophysics Data System (ADS)

    Junqueira, S.; Combes, F.

    1997-12-01

    The authors report preliminary results of self-gravitating simulations of spiral galaxies modeled by two components, stellar and gaseous disks. One of the objectives of this work is to study asymmetries in the distribution of the gas, features observed for a number of spiral galaxies. The gas disk is simulated by the Beam-Scheme method, where the gas is considered as a fluid. The results suggest that very concentrated galactic disks can be unstable to the one-armed (m = 1) spiral perturbation, which may explain the asymmetric patterns observed in isolated galaxies.

  11. Properties of accretion disk coronae

    NASA Technical Reports Server (NTRS)

    Wilms, J.; Dove, J.; Staubert, R.; Begelman, M. C.

    1997-01-01

    The properties of accretion disk corona in a parameter regime suitable for Galactic black hole candidates are considered and the results of an analysis of these properties using a self-consistent Monte Carlo code are presented. Examples of the coronal temperature structure, the shape and angular dependency of the spectrum and the maximum temperature allowed for each optical depth of the corona are presented. It is shown that the observed spectrum of the Galactic black hole candidate Cygnus X-1 cannot be explained by accreting disk corona models with a slab geometry, where the accretion disk is sandwiched by the comptonizing medium.

  12. Recognizing Patterns in Debris Disks

    NASA Technical Reports Server (NTRS)

    Kuchner, Marc

    2009-01-01

    An extrasolar planet sculpts the famous debris dish around Fomalhaut; probably many other debris disks contain planets that we could locate if only we could better recognize their signatures in the dust that surrounds them. I will describe the latest 3-D models of debris dish dynamics / models that include planets, grain-grain collisions and even ISM-disk interactions. I will show why all these ingredients are needed to explain disk images--and what the images are telling us about planet formation.

  13. Vibration Based Crack Detection in a Rotating Disk. Part 1; An Analytical Study

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Baaklini, George Y.

    2003-01-01

    This paper describes the analytical results concerning the detection of a crack in a rotating disk. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk's geometry as well as a change in the system s center of mass occurs. Finite element analyses were conducted concerning a notched disk in order to define the sensitivity of the method. The notch was used to simulate an actual crack and will be the method utilized for upcoming experiments. Various notch sizes were studied. The geometric deformations and shifts of center of mass were documented as a function of rotational speed. In addition, a rotordynamic analysis of a 2-bearing, disk and shaft system was conducted. The overall response of the system was required in order to design the experimental system for operation beyond the first critical. The results of the FE analyses of the disk indicated that the overall changes in the disk s geometry and center of mass were rather small. The difference between the maximum centrifugal radial displacements between the undamaged and damaged disks at 8000 RPM was 0.00014 in. for a 0.963 in. notch length. The shift in center of mass was also of this magnitude. The next step involves running experiments to verify the analysis.

  14. Radiative Transfer in Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Graziani, L.; Aiello, S.; Belleni-Morante, A.; Cecchi-Pestellini, C.

    2008-09-01

    Abstract Protoplanetary disks are the precursors of planetary systems. All building materials needed to assembly the planetary systems are supplied by these reservoirs, including many organic molecules [1,2]. Thus, the physical and chemical properties in Protoplanetary disks set the boundary conditions for the formation and evolution of planets and other solar system bodies. In standard radiative scenario structure and chemistry of protoplanetary disks depend strongly on the nature of central star around which they formed. The dust temperature is manly set by the stellar luminosity, while the chemistry of the whole disk depends on the UV and X ray fluxes [3,4,6,8]. Therefore, a knowledge as accurate as possible of the radiative transfer (RT) inside disks is a prerequisite for their modelling. Actually, real disks are complex, stratified and inhomogeneous environments requiring a detailed dust mixture modelling and the ability to follow the radiation transfer across radial and vertical gradients. Different energetic processes as the mass accretion processes onto the star surface, the viscous dissipative heating dominating the midplane region, and the flared atmospheres radiation reprocessing, have a significant role in the disk structuring [4,5,8]. During the last 10 years many authors suggested various numerical and analytical techniques to resolve the disk temperature structure providing vertical temperature profiles and disk SED databases [4,6]. In this work we present the results of our semi analytical and numerical model solving the radiative transfer problem in two separate interesting disk regions: 1) Disk atmospheres at large radius, r > 10 AU. 2) Vertical disk structure over 1 < r < 10 AU and 10 < r < 100 AU. A simplified analytical approach based on P-N approximation [7] for a rectified disk surface (suitable for limited range of r) is compared and contrasted with a more accurate Monte Carlo integration [5]. Our code can handle arbitrary dust

  15. 40 CFR 761.208 - Obtaining manifests.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... print the manifest under 40 CFR 262.21 (c) and (e). A registered source may be a: (i) State agency; (ii) Commercial printer; (iii) PCB waste generator, transporter or, designated facility; or (iv) PCB waste broker... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.208 Obtaining manifests. (a)(1) A generator may...

  16. 40 CFR 761.208 - Obtaining manifests.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... print the manifest under 40 CFR 262.21 (c) and (e). A registered source may be a: (i) State agency; (ii) Commercial printer; (iii) PCB waste generator, transporter or, designated facility; or (iv) PCB waste broker... PROHIBITIONS PCB Waste Disposal Records and Reports § 761.208 Obtaining manifests. (a)(1) A generator may...

  17. Teaching about Manifest Destiny: Clarifying the Concept.

    ERIC Educational Resources Information Center

    Chiodo, John J.

    2000-01-01

    Provides information on Manifest Destiny and the expansionist ideals of the United States, especially during the 19th century. Offers a lesson plan that will help students understand the concept of Manifest Destiny, including an assessment activity, how to expand the lesson, an appendix, and references. (CMK)

  18. 19 CFR 123.32 - Manifests.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Manifests. 123.32 Section 123.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY CBP RELATIONS WITH CANADA AND MEXICO Shipments in Transit Through the United States § 123.32 Manifests. (a)...

  19. Clinical manifestations of zinc deficiency.

    PubMed

    Prasad, A S

    1985-01-01

    The essentiality of zinc for humans was recognized in the early 1960s. The causes of zinc deficiency include malnutrition, alcoholism, malabsorption, extensive burns, chronic debilitating disorders, chronic renal diseases, following uses of certain drugs such as penicillamine for Wilson's disease and diuretics in some cases, and genetic disorders such as acrodermatitis enteropathica and sickle cell disease. In pregnancy and during periods of growth the requirement of zinc is increased. The clinical manifestations in severe cases of zinc deficiency include bullous-pustular dermatitis, alopecia, diarrhea, emotional disorder, weight loss, intercurrent infections, hypogonadism in males; it is fatal if unrecognized and untreated. A moderate deficiency of zinc is characterized by growth retardation and delayed puberty in adolescents, hypogonadism in males, rough skin, poor appetite, mental lethargy, delayed wound healing, taste abnormalities, and abnormal dark adaptation. In mild cases of zinc deficiency in human subjects, we have observed oligospermia, slight weight loss, and hyperammonemia. Zinc is a growth factor. Its deficiency adversely affects growth in many animal species and humans. Inasmuch as zinc is needed for protein and DNA synthesis and for cell division, it is believed that the growth effect of zinc is related to its effect on protein synthesis. Whether or not zinc is required for the metabolism of somatomedin needs to be investigated in the future. Testicular functions are affected adversely as a result of zinc deficiency in both humans and experimental animals. This effect of zinc is at the end organ level; the hypothalamic-pituitary axis is intact in zinc-deficient subjects. Inasmuch as zinc is intimately involved in cell division, its deficiency may adversely affect testicular size and thus affect its functions. Zinc is required for the functions of several enzymes and whether or not it has an enzymatic role in steroidogenesis is not known at present

  20. THE MASS-INDEPENDENCE OF SPECIFIC STAR FORMATION RATES IN GALACTIC DISKS

    SciTech Connect

    Abramson, Louis E.; Gladders, Michael D.; Kelson, Daniel D.; Dressler, Alan; Oemler, Augustus Jr.; Poggianti, Bianca; Vulcani, Benedetta

    2014-04-20

    The slope of the star formation rate/stellar mass relation (the SFR {sup M}ain Sequence{sup ;} SFR-M {sub *}) is not quite unity: specific star formation rates (SFR/M {sub *}) are weakly but significantly anti-correlated with M {sub *}. Here we demonstrate that this trend may simply reflect the well-known increase in bulge mass-fractions—portions of a galaxy not forming stars—with M {sub *}. Using a large set of bulge/disk decompositions and SFR estimates derived from the Sloan Digital Sky Survey, we show that re-normalizing SFR by disk stellar mass (sSFR{sub disk} ≡ SFR/M {sub *,} {sub disk}) reduces the M {sub *} dependence of SF efficiency by ∼0.25 dex per dex, erasing it entirely in some subsamples. Quantitatively, we find log sSFR{sub disk}-log M {sub *} to have a slope β{sub disk} in [ – 0.20, 0.00] ± 0.02 (depending on the SFR estimator and Main Sequence definition) for star-forming galaxies with M {sub *} ≥ 10{sup 10} M {sub ☉} and bulge mass-fractions B/T ≲ 0.6, generally consistent with a pure-disk control sample (β{sub control} = –0.05 ± 0.04). That (SFR/M {sub *,} {sub disk}) is (largely) independent of host mass for star-forming disks has strong implications for aspects of galaxy evolution inferred from any SFR-M {sub *} relation, including manifestations of ''mass quenching'' (bulge growth), factors shaping the star-forming stellar mass function (uniform dlog M {sub *}/dt for low-mass, disk-dominated galaxies), and diversity in star formation histories (dispersion in SFR(M {sub *}, t)). Our results emphasize the need to treat galaxies as composite systems—not integrated masses—in observational and theoretical work.

  1. Rewriteable optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Shull, Thomas A.; Rinsland, Pamela L.

    1991-01-01

    A NASA program to develop a high performance (high rate, high capability) rewriteable optical disk recorder for spaceflight applications is presented. An expandable, adaptable system concept is proposed based on disk Drive modules and a modular Controller. Drive performance goals are 10 gigabyte capacity are up to 1.8 gigabits per second rate with concurrent I/O, synchronous data transfer, and 2 to 5 years operating life in orbit. Technology developments, design concepts, current status, and future plans are presented.

  2. Resolved Observations of Transition Disks

    NASA Astrophysics Data System (ADS)

    Casassus, Simon

    2016-04-01

    Resolved observations are bringing new constraints on the origin of radial gaps in protoplanetary disks. The kinematics, sampled in detail in one case-study, are indicative of non-Keplerian flows, corresponding to warped structures and accretion which may both play a role in the development of cavities. Disk asymmetries seen in the radio continuum are being interpreted in the context of dust segregation via aerodynamic trapping. We summarise recent observational progress, and describe prospects for improvements in the near term.

  3. Spiral Waves in Accretion Disks

    NASA Astrophysics Data System (ADS)

    Harlaftis, Emilios

    A review with the most characteristic spiral waves in accretion disks of cataclysmic variables will be presented. Recent work on experiments targeting the detection of spiral waves from time lapse movies of real disks and the study of permanent spiral waves will be discussed. The relevance of spiral waves with other systems such as star-planet X-ray binaries and Algols will be reviewed.

  4. CHEMICAL PROCESSES IN PROTOPLANETARY DISKS

    SciTech Connect

    Walsh, Catherine; Millar, T. J.; Nomura, Hideko

    2010-10-20

    We have developed a high-resolution combined physical and chemical model of a protoplanetary disk surrounding a typical T Tauri star. Our aims were to use our model to calculate the chemical structure of disks on small scales (submilliarcsecond in the inner disk for objects at the distance of Taurus, {approx}140 pc) to investigate the various chemical processes thought to be important in disks and to determine potential molecular tracers of each process. Our gas-phase network was extracted from the UMIST Database for Astrochemistry to which we added gas-grain interactions including freezeout and thermal and non-thermal desorption (cosmic-ray-induced desorption, photodesorption, and X-ray desorption), and a grain-surface network. We find that cosmic-ray-induced desorption has the least effect on our disk chemical structure while photodesorption has a significant effect, enhancing the abundances of most gas-phase molecules throughout the disk and affecting the abundances and distribution of HCN, CN, and CS, in particular. In the outer disk, we also see enhancements in the abundances of H{sub 2}O and CO{sub 2}. X-ray desorption is a potentially powerful mechanism in disks, acting to homogenize the fractional abundances of gas-phase species across the depth and increasing the column densities of most molecules, although there remain significant uncertainties in the rates adopted for this process. The addition of grain-surface chemistry enhances the fractional abundances of several small complex organic molecules including CH{sub 3}OH, HCOOCH{sub 3}, and CH{sub 3}OCH{sub 3} to potentially observable values (i.e., a fractional abundance of {approx}>10{sup -11}).

  5. THE ORIGIN OF THE NEGATIVE TORQUE DENSITY IN DISK-SATELLITE INTERACTION

    SciTech Connect

    Rafikov, Roman R.; Petrovich, Cristobal

    2012-03-01

    Tidal interaction between a gaseous disk and a massive orbiting perturber is known to result in angular momentum exchange between them. Understanding astrophysical manifestations of this coupling such as gap opening by planets in protoplanetary disks or clearing of gas by binary supermassive black holes (SMBHs) embedded in accretion disks requires knowledge of the spatial distribution of the torque exerted on the disk by a perturber. Recent hydrodynamical simulations by Dong et al have shown evidence for the tidal torque density produced in a uniform disk to change sign at the radial separation of Almost-Equal-To 3.2 scale heights from the perturber's orbit, in clear conflict with the previous studies. To clarify this issue, we carry out a linear calculation of the disk-satellite interaction putting special emphasis on understanding the behavior of the perturbed fluid variables in physical space. Using analytical as well as numerical methods, we confirm the reality of the negative torque density phenomenon and trace its origin to the overlap of Lindblad resonances in the vicinity of the perturber's orbit-an effect not accounted for in previous studies. These results suggest that calculations of the gap and cavity opening in disks by planets and binary SMBHs should rely on more realistic torque density prescriptions than the ones used at present.

  6. Jets from magnetized accretion disks

    NASA Astrophysics Data System (ADS)

    Matsumoto, Ryoji

    When an accretion disk is threaded by large scale poloidal magnetic fields, the injection of magnetic helicity from the accretion disk drives bipolar outflows. We present the results of global magnetohydrodynamic (MHD) simulations of jet formation from a torus initially threaded by vertical magnetic fields. After the torsional Alfvén waves generated by the injected magnetic twists propagate along the large-scale magnetic field lines, magnetically driven jets emanate from the surface of the torus. Due to the magnetic pinch effect, the jets are collimated along the rotation axis. Since the jet formation process extracts angular momentum from the disk, it enhances the accretion rate of the disk material. Through three-dimensional (3D) global MHD simulations, we confirmed previous 2D results that the magnetically braked surface of the disk accretes like an avalanche. Owing to the growth of non-axisymmetric perturbations, the avalanche flow breaks up into spiral channels. Helical structure also appears inside the jet. When magnetic helicity is injected into closed magnetic loops connecting the central object and the accretion disk, it drives recurrent magnetic reconnection and outflows.

  7. The Evolutionary State of Anemic Circumstellar Disks in IC 348: Transitions Disks, The Earliest Debris Disks, and Terrestrial Planet Formation

    NASA Astrophysics Data System (ADS)

    Currie, Thayne M.

    2008-05-01

    I investigate the evolution of 3 Myr-old MIPS-detected circumstellar disks in IC 348 that may be in an intermediate stage between primordial, optically-thick disks of gas/dust and debris disks characteristic of the final stages of planet formation. I demonstrate that these anemic disks are not a homogenous class of objects corresponding to a unique evolutionary state. Analysis of their mid-IR colors, accretion signatures (or lack thereof), and SED modeling suggest that such disks around early spectral type stars are most likely warm debris disks indicative of terrestrial planet formation: perhaps the youngest yet known. MIPS-detected anemic disks around later (M) stars are likely evolved primordial disks such as transition disks. Anemic disks surrounding G and K stars contain both populations. IC 348 also contains a small number of non-accreting sources with weak 24 micron emission characteristic of cold debris disks. The difference in evolutionary states between anemic disks surrounding early type vs. late-type stars is consistent with a mass-dependent evolution of circumstellar disks from the primordial disk phase through the debris disk phase similar to that found for 5 Myr-old Upper Scorpius.

  8. On the structure of the plasma disk in the Jovian magnetosphere

    NASA Astrophysics Data System (ADS)

    Bespalov, P. A.; Davydenko, S. S.

    1994-07-01

    We have determined the structure of the low-energy plasma disk in the middle Jovian magnetosphere. First, the shape of the dense plasma structures have been described analytically. We have investigated a distribution of the background plasma along the arbitrary magnetic flux tube in the frame of diffuse equilibrium taking into account the action of centrifugal and gravitational forces. Using the results of this investigation we have shown that background plasma density reaches the maximum on the surface, consisting of the warped disk between the magnetic and centrifugal equators outside Io's orbit and two mirror symmetrical 'petals' in the region of the polar cusps. Second, the radial profile of plasma density in the disk has been studied. We have considered the magnetohydrodynamic (MHD) stability of the low-latitude dense plasma disk formed under the action of centrifugal force. The equilibrium radial distribution of the plasma was found for the plasma disk at the threshold of the instability with respect to small-scale MHD perturbations. The effect of the finite ion Larmor radius at the threshold of plasma instability was taken into account. We have estimated the influence of the inhomogeneity of the plasma perturbations along the magnetic field on the radial density profile bearing in mind the finite conductivity of the Jovian ionosphere. A relationship between the thickness of the plasma disk and the radial plasma distribution has been pointed out. The results obtained were compared with the known experimental data for the Jovian plasma sheet.

  9. GROWTH OF GRAINS IN BROWN DWARF DISKS

    SciTech Connect

    Meru, Farzana; Galvagni, Marina; Olczak, Christoph

    2013-09-01

    We perform coagulation and fragmentation simulations using the new physically motivated model by Garaud et al. to determine growth locally in brown dwarf disks. We show that large grains can grow and that if brown dwarf disks are scaled-down versions of T Tauri disks (in terms of stellar mass, disk mass, and disk radius) growth at an equivalent location with respect to the disk truncation radius can occur to the same size in both disks. We show that similar growth occurs because the collisional timescales in the two disks are comparable. Our model may therefore potentially explain the recent observations of grain growth to millimeter sizes in brown dwarf disks, as seen in T Tauri disks.

  10. Magneto-thermal Disk Winds from Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Bai, Xue-Ning; Ye, Jiani; Goodman, Jeremy; Yuan, Feng

    2016-02-01

    The global evolution and dispersal of protoplanetary disks (PPDs) are governed by disk angular-momentum transport and mass-loss processes. Recent numerical studies suggest that angular-momentum transport in the inner region of PPDs is largely driven by magnetized disk wind, yet the wind mass-loss rate remains unconstrained. On the other hand, disk mass loss has conventionally been attributed to photoevaporation, where external heating on the disk surface drives a thermal wind. We unify the two scenarios by developing a one-dimensional model of magnetized disk winds with a simple treatment of thermodynamics as a proxy for external heating. The wind properties largely depend on (1) the magnetic field strength at the wind base, characterized by the poloidal Alfvén speed vAp, (2) the sound speed cs near the wind base, and (3) how rapidly poloidal field lines diverge (achieve {R}-2 scaling). When {v}{Ap}\\gg {c}{{s}}, corotation is enforced near the wind base, resulting in centrifugal acceleration. Otherwise, the wind is accelerated mainly by the pressure of the toroidal magnetic field. In both cases, the dominant role played by magnetic forces likely yields wind outflow rates that exceed purely hydrodynamical mechanisms. For typical PPD accretion-rate and wind-launching conditions, we expect vAp to be comparable to cs at the wind base. The resulting wind is heavily loaded, with a total wind mass-loss rate likely reaching a considerable fraction of the wind-driven accretion rate. Implications for modeling global disk evolution and planet formation are also discussed.

  11. Resonances and circuit theory for the interaction of metallic disks and annuli with an electromagnetic field.

    PubMed

    Chui, S T; Du, J J; Yau, S T

    2014-11-01

    To understand the nature of the electromagnetic resonances of finite metallic surfaces, we formulate a rigorous and rapidly convergent circuit theory for the interaction of a metallic disk and a metallic annulus with an electromagnetic field. Expressions for the current induced and the resonance condition are derived. A new understanding of the nature of the resonances is obtained. For half of the resonances we find a divergent electric field at the edge of the disk, even though it is smooth in shape. For the disk, we compare with previous results using vector spheroidal wave functions and found good agreement for the resonance condition. Our approach can be generalized to other finite surfaces. PMID:25493895

  12. [Lyme disease--clinical manifestations and treatment].

    PubMed

    Stock, Ingo

    2016-05-01

    Lyme disease (Lyme borreliosis) is a systemic infectious disease that can present in a variety of clinical manifestations. The disease is caused by a group of spirochaetes--Borrelia burgdorferi sensu lato or Lyme borrelia--that are transmitted to humans by the bite of Ixodes ticks. Lyme disease is the most common arthropode-borne infectious disease in many European countries including Germany. Early localized infection is typically manifested by an erythema migrans skin lesion, in rarer cases as a borrelial lymphocytoma. The most common early disseminated manifestation is (early) neuroborreliosis. In adults, neuroborreliosis appears typically as meningoradiculoneuritis. Neuroborreliosis in children, however, is typically manifested by meningitis. In addition, multiple erythema migrans lesions and Lyme carditis occur relatively frequently. The most common manifestation oflate Lyme disease is Lyme arthritis. Early manifestations (and usually also late manifestations) of Lyme disease can be treated successfully by application of suitable antibacterial agents. For the treatment of Lyme disease, doxycycline, certain penicillins such as amoxicillin and some cephalosporins (ceftriaxone, cefotaxime, cefuroxime axetil) are recommended in current guidelines. A major challenge is the treatment of chronic, non-specific disorders, i. e., posttreatment Lyme disease syndrome and "chronic Lyme disease". Prevention of Lyme disease is mainly accomplished by protecting against tick bites. Prophylactic administration of doxycycline after tick bites is generally not recommended in Germany. There is no vaccine available for human beings. PMID:27348896

  13. Saturn - UBV photoelectric pinhole scans of the disk. II

    NASA Technical Reports Server (NTRS)

    Price, M. J.; Franz, O. G.

    1980-01-01

    During the 1980 Saturn apparition, UBV pinhole scans of the disk were obtained with a photoelectric area-scanning photometer. An analysis of these data reveals that the atmosphere of Saturn can be represented by a finite clear H2 layer overlying a semiinfinite absorbent aerosol haze. The extent of the clear H2 region appears to be latitude-dependent; the H2 column density varies systematically from about 15 km-am over the equatorial and polar regions to about 31 km-am at temperate latitudes. A previous conclusion that the aerosol haze is strongly absorbent in the UV is confirmed; its effective U-band single-scattering albedo is about 0.4. Latitudinal disk structure at visual wavelengths appears to be the result of local variations in the volume density of absorbent particles in the aerosol layer.

  14. Driving of Accretion Disk Variability by the Disk Dynamo

    NASA Astrophysics Data System (ADS)

    Hogg, J. Drew; Reynolds, Christopher S.

    2016-01-01

    Variability is a univeral feature of emission from accreting objects, but many questions remain as to how the variability is driven and how it relates to the underlying accretion physics. We use a long, semi-global MHD simulation of a thin accretion disk around a black hole to perform a detailed study of the fluctuations in the internal disk stress and the affect these fluctuations have on the accretion flow. In this poster, we show that low frequency fluctuations in the effective α-parameter in the disk are due to oscillations of the disk dynamo. Additionally, we show that fluctuations in the effective α-parameter drive "propagating fluctuations" in mass accretion rate through the disk that qualitatively resemble the variability from astrophysical black hole systems. In particular, we show that several of the ubiquitous phenomenological properties of black hole variability, including log-normal flux distributions, RMS-flux relationships, and radial coherence are present in the mass accretion rate fluctuations of our simulation.

  15. ACCRETING CIRCUMPLANETARY DISKS: OBSERVATIONAL SIGNATURES

    SciTech Connect

    Zhu, Zhaohuan

    2015-01-20

    I calculate the spectral energy distributions of accreting circumplanetary disks using atmospheric radiative transfer models. Circumplanetary disks only accreting at 10{sup –10} M {sub ☉} yr{sup –1} around a 1 M{sub J} planet can be brighter than the planet itself. A moderately accreting circumplanetary disk ( M-dot ∼10{sup −8} M{sub ⊙} yr{sup −1}; enough to form a 10 M{sub J} planet within 1 Myr) around a 1 M{sub J} planet has a maximum temperature of ∼2000 K, and at near-infrared wavelengths (J, H, K bands), this disk is as bright as a late-M-type brown dwarf or a 10 M{sub J} planet with a ''hot start''. To use direct imaging to find the accretion disks around low-mass planets (e.g., 1 M{sub J} ) and distinguish them from brown dwarfs or hot high-mass planets, it is crucial to obtain photometry at mid-infrared bands (L', M, N bands) because the emission from circumplanetary disks falls off more slowly toward longer wavelengths than those of brown dwarfs or planets. If young planets have strong magnetic fields (≳100 G), fields may truncate slowly accreting circumplanetary disks ( M-dot ≲10{sup −9} M{sub ⊙} yr{sup −1}) and lead to magnetospheric accretion, which can provide additional accretion signatures, such as UV/optical excess from the accretion shock and line emission.

  16. Chemical probes in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Guzman, Viviana; Oberg, Karin I.; Loomis, Ryan A.; Qi, Chunhua

    2016-06-01

    Protoplanetary disks provide the material for new planetary systems. Moreover, the location and composition of nascent planets will depend on the chemical and physical structure of disks. The radiation field and gas temperature, as well as the chemical structure and composition in disks can be probed by the emission and spatial distribution of molecules.I will present ALMA observations of different molecular lines in protoplanetary disks and discuss chemical probes frequently used in the ISM and in our Solar system that, thanks the spectacular capabilities of ALMA, can now be applied to protoplanetary disks. First, the CN/HCN ratio, which is a good tracer of radiation field, because CN is a major product of HCN photodissociation. Second, Nitrogen isotopic ratios, which are widely used to trace the origin of molecules in our Solar system, can also be used to trace the thermal structure in disks, since 15N fractionation should depend sensitively on the formation temperature. Finally, the H2CO ortho-to-para ratio has great potential to constrain its formation pathway, because different values are expected if it forms in the gas or on grain surfaces.Thanks to ALMA we now have the sensitivity and angular resolution to detect and spatially resolve the emission of many new species in disks. However, in order to fully benefit from these observations, great progresses must also be made on the theoretical and experimental sides. This includes the need for spectroscopic constants, collisional rates, photodissociation rates, formation/destruction rates, and a better understanding on the interplay between the gas-phase and solid-phase chemistry.

  17. Dust in protoplanetary disks: observations

    NASA Astrophysics Data System (ADS)

    Waters, L. B. F. M.

    2015-09-01

    Solid particles, usually referred to as dust, are a crucial component of interstellar matter and of planet forming disks surrounding young stars. Despite the relatively small mass fraction of ≈1% (in the solar neighborhood of our galaxy; this number may differ substantially in other galaxies) that interstellar grains represent of the total mass budget of interstellar matter, dust grains play an important role in the physics and chemistry of interstellar matter. This is because of the opacity dust grains at short (optical, UV) wavelengths, and the surface they provide for chemical reactions. In addition, dust grains play a pivotal role in the planet formation process: in the core accretion model of planet formation, the growth of dust grains from the microscopic size range to large, cm-sized or larger grains is the first step in planet formation. Not only the grain size distribution is affected by planet formation. Chemical and physical processes alter the structure and chemical composition of dust grains as they enter the protoplanetary disk and move closer to the forming star. Therefore, a lot can be learned about the way stars and planets are formed by observations of dust in protoplanetary disks. Ideally, one would like to measure the dust mass, the grain size distribution, grain structure (porosity, fluffiness), the chemical composition, and all of these as a function of position in the disk. Fortunately, several observational diagnostics are available to derive constrains on these quantities. In combination with rapidly increasing quality of the data (spatial and spectral resolution), a lot of progress has been made in our understanding of dust evolution in protoplanetary disks. An excellent review of dust evolution in protoplanetary disks can be found in Testi et al. (2014). 2nd Lecture of the Summer School "Protoplanetary Disks: Theory and Modelling Meet Observations"

  18. Star-Disk Coupling Mechanisms

    NASA Astrophysics Data System (ADS)

    Shu, F. H.

    2002-05-01

    We attempt to clarify the confusion concerning angular-momentum coupling mechanisms when closed and open magnetic fields originating from a young star thread through a surrounding disk. We argue that the traditional Ghosh & Lamb description represents only a transient behavior that does not account for important longer-term effects that arise because of accretion and if the disk is highly, but imperfectly, electrically conducting. In the latter case, we argue that the steady-state response of the system is to form a funnel-flow/x-wind geometry. We describe approximate, self-consistent, calculations of the gas flow for the case when the unperturbed magnetic-field configuration of the star would have been a pure dipole in the absence of the disk. We show that the disk-star interactions considerably modifies the actual magnetospheric structure of the system. We also show calculations where we drop the assumption that the unperturbed magnetosphere is a pure dipole. As long as the radius of the inner edge of the disk is a few or more times the radius of the star, we find that the properties of the x-wind are little changed by the relaxation of the dipole assumption. However, the size and geometry of the hot spots where the funnel flow impacts the star can be greatly affected by the exact mixture of multipoles chosen to model the magnetic fields on the stellar surface. The crucial invariant in our theory is the amount of trapped flux required to truncate a disk of a certain accretion rate before the flow reaches the equator of a star of given mass. We present empirical evidence that trapped flux is indeed the relevant concept for the explanation of the hot-spot properties of T Tauri stars. We close with a qualitative discussion of the limits of the validity of the concept of disk locking. This research is supported in part by grants from NASA and the National Science Foundation.

  19. Genetic alterations in syndromes with oral manifestations

    PubMed Central

    Anuthama, Krishnamurthy; Prasad, Harikrishnan; Ramani, Pratibha; Premkumar, Priya; Natesan, Anuja; Sherlin, Herald J.

    2013-01-01

    Ever since Gregor Johan Mendel proposed the law of inheritance, genetics has transcended the field of health and has entered all walks of life in its application. Thus, the gene is the pivoting factor for all happenings revolving around it. Knowledge of gene mapping in various diseases would be a valuable tool in prenatally diagnosing the condition and averting the future disability and stigma for the posterity. This article includes an array of genetically determined conditions in patients seen at our college out-patient department with complete manifestation, partial manifestation and array of manifestations not fitting into a particular syndrome. PMID:24379857

  20. Paraneoplastic cutaneous manifestations: concepts and updates*

    PubMed Central

    da Silva, Josenilson Antônio; Mesquita, Kleyton de Carvalho; Igreja, Ana Carolina de Souza Machado; Lucas, Isabella Cristina Rodrigues Naves; Freitas, Aline Ferreira; de Oliveira, Sandra Maximiano; Costa, Izelda Maria Carvalho; Campbell, Iphis Tenfuss

    2013-01-01

    The skin often signals systemic changes. Some neoplastic diseases that affect internal organs may trigger several cutaneous manifestations. Although these dermatoses are relatively unusual, the recognition of some typical paraneoplastic dermatoses may lead to the early diagnosis of a neoplasm and determine a better prognosis. In this review article, we discuss the paraneoplastic cutaneous manifestations strongly associated with neoplasms, which include acanthosis nigricans maligna, tripe palms, erythema gyratum repens, Bazex syndrome, acquired hypertrichosis lanuginosa, necrolytic migratory erythema, Leser-Trélat sign and paraneoplastic pemphigus. We also review the clinical manifestations of each condition and include updated knowledge on disease pathogenesis. PMID:23538999

  1. Wegener Granulomatosis: Otologic Manifestation as First Symptom

    PubMed Central

    Costa, Carla Fabiane da; Polanski, Jose Fernando

    2014-01-01

    Introduction Wegener granulomatosis is a systemic vasculitis affecting small and medium-sized vessels of the upper and lower respiratory tract and kidneys. Objective To describe a case of Wegener disease with atypical manifestation. Resumed Report We describe the case of a 50-year-old woman with chronic otitis media and sensorineural hearing loss as the primary symptoms, without other manifestations. Conclusion In cases of acute ear manifestations with or without hearing loss and with poor response to usual treatments, Wegener granulomatosis should be included among the possible etiologies. After adequate diagnoses and treatment of this rare disease, there was favorable evolution. PMID:26157503

  2. A thermal, thermoelastic, and wear analysis of high-energy disk brakes

    NASA Technical Reports Server (NTRS)

    Kennedy, F. E., Jr.; Wu, J. J.; Ling, F. F.

    1974-01-01

    A thermomechanical investigation of the sliding contact problem encountered in high-energy disk brakes is described. The analysis includes a modelling, using the finite element method of the thermoelastic instabilities that cause transient changes in contact area to occur on the friction surface. In order to include the effect of wear at the contact surface, a wear criterion is proposed that results in the prediction of wear rates for disk brakes that are quite close to experimentally determined wear rates. The thermal analysis shows that the transient temperature distribution in a disk brake assembly can be determined more accurately by use of this thermomechanical analysis than by a more conventional analysis that assumes constant contact conditions. It also shows that lower, more desirable, temperatures in disk brakes can be attained by increasing the volume, the thermal conductivity, and, especially, the heat capacity of the brake components.

  3. Modeling self-subtraction in angular differential imaging: Application to the HD 32297 debris disk

    SciTech Connect

    Esposito, Thomas M.; Fitzgerald, Michael P.; Graham, James R.; Kalas, Paul

    2014-01-01

    We present a new technique for forward-modeling self-subtraction of spatially extended emission in observations processed with angular differential imaging (ADI) algorithms. High-contrast direct imaging of circumstellar disks is limited by quasi-static speckle noise, and ADI is commonly used to suppress those speckles. However, the application of ADI can result in self-subtraction of the disk signal due to the disk's finite spatial extent. This signal attenuation varies with radial separation and biases measurements of the disk's surface brightness, thereby compromising inferences regarding the physical processes responsible for the dust distribution. To compensate for this attenuation, we forward model the disk structure and compute the form of the self-subtraction function at each separation. As a proof of concept, we apply our method to 1.6 and 2.2 μm Keck adaptive optics NIRC2 scattered-light observations of the HD 32297 debris disk reduced using a variant of the 'locally optimized combination of images' algorithm. We are able to recover disk surface brightness that was otherwise lost to self-subtraction and produce simplified models of the brightness distribution as it appears with and without self-subtraction. From the latter models, we extract radial profiles for the disk's brightness, width, midplane position, and color that are unbiased by self-subtraction. Our analysis of these measurements indicates a break in the brightness profile power law at r ≈ 110 AU and a disk width that increases with separation from the star. We also verify disk curvature that displaces the midplane by up to 30 AU toward the northwest relative to a straight fiducial midplane.

  4. Modeling Self-subtraction in Angular Differential Imaging: Application to the HD 32297 Debris Disk

    NASA Astrophysics Data System (ADS)

    Esposito, Thomas M.; Fitzgerald, Michael P.; Graham, James R.; Kalas, Paul

    2014-01-01

    We present a new technique for forward-modeling self-subtraction of spatially extended emission in observations processed with angular differential imaging (ADI) algorithms. High-contrast direct imaging of circumstellar disks is limited by quasi-static speckle noise, and ADI is commonly used to suppress those speckles. However, the application of ADI can result in self-subtraction of the disk signal due to the disk's finite spatial extent. This signal attenuation varies with radial separation and biases measurements of the disk's surface brightness, thereby compromising inferences regarding the physical processes responsible for the dust distribution. To compensate for this attenuation, we forward model the disk structure and compute the form of the self-subtraction function at each separation. As a proof of concept, we apply our method to 1.6 and 2.2 μm Keck adaptive optics NIRC2 scattered-light observations of the HD 32297 debris disk reduced using a variant of the "locally optimized combination of images" algorithm. We are able to recover disk surface brightness that was otherwise lost to self-subtraction and produce simplified models of the brightness distribution as it appears with and without self-subtraction. From the latter models, we extract radial profiles for the disk's brightness, width, midplane position, and color that are unbiased by self-subtraction. Our analysis of these measurements indicates a break in the brightness profile power law at r ≈ 110 AU and a disk width that increases with separation from the star. We also verify disk curvature that displaces the midplane by up to 30 AU toward the northwest relative to a straight fiducial midplane.

  5. Lightcurves of Extreme Debris Disks

    NASA Astrophysics Data System (ADS)

    Rieke, George; Meng, Huan; Su, Kate

    2012-12-01

    We have recently discovered that some planetary debris disks with extreme fractional luminosities are variable on the timescale of a few years. This behavior opens a new possibility to understand planet building. Two of the known variable disks are around solar-like stars in the age range of 30 to 100+ Myr, which is the expected era of the final stages of terrestrial planet building. Such variability can be attributed to violent collisions (up to ones on the scale of the Moon-forming event between the proto-Earth and another proto-planet). The collisional cascades that are the aftermaths of these events can produce large clouds of tiny dust grains, possibly even condensed from silica vapor. A Spitzer pilot program has obtained the lightcurve of such a debris disk and caught two minor outbursts. Here we propose to continue the lightcurve monitoring with higher sampling rates and to expand it to more disks. The proposed time domain observations are a new dimension of debris disk studies that can bring unique insight to their evolution, providing important constraints on the collisional and dynamical models of terrestrial planet formation.

  6. Studies of Circumstellar Disk Evolution

    NASA Technical Reports Server (NTRS)

    Hartmann, Lee W.

    2004-01-01

    Spitzer Space Telescope infrared data for our program on disk evolution has been taken (the main IRAC - 3-8 micron exposures; the 24 and 70 micron MIPS data are to come later). We now have deep maps in the four IRAC bands of the 3-Myr-old cluster Trumpler 37, and the 10-Myr-old cluster NGC 7160. Analysis of these data has now begun. We will be combining these data with our ground-based photometric and spectroscopic data to obtain a complete picture of disk frequency as a function of mass through this important age range, which spans the likely epoch of (giant) planet formation in most systems. Analysis of the SIRTF data, and follow-on ground-based spectroscopy on the converted MMT telescope using the wide-field, fiber-fed, multiobject spectrographs, Hectospec and Hectochelle, will be the major activity during the next year.Work was also performed on the following: protoplanetary disk mass accretion rates in very low-mass stars; the inner edge of T Tauri disks; accretion in intermediate-mass T Tauri stars (IMPS); and the near-infrared spectra of the rapidly-accreting protostellar disks FU Ori and V1057 Cyg.

  7. Heat transfer characteristics for disk fans

    NASA Astrophysics Data System (ADS)

    Prikhodko, Yu. M.; Chekhov, V. P.; Fomichev, V. P.

    2014-08-01

    Multiple-disk fans belong to the class of friction machines; they can be designed in two variants: centrifugal disk fans and diametrical disk fans. Flow patterns in these two types of machines are different, and they possess different heat transfer characteristics. The paper presents results of experimental study for a centrifugal disk fan under atmospheric pressure with air taken as working gas. The radial temperature distribution for a disk was obtained at different rotation speed of the rotor and different heating of the disks. Heat transfer characteristics of a centrifugal disk fan and a diametrical disk fan were compared. The research results demonstrate a higher heat transfer efficiency for centrifugal design versus diametrical disk design.

  8. Endocrine disorders and the neurologic manifestations

    PubMed Central

    2014-01-01

    The nervous system and the endocrine system are closely interrelated and both involved intimately in maintaining homeostasis. Endocrine dysfunctions may lead to various neurologic manifestations such as headache, myopathy, and acute encephalopathy including coma. It is important to recognize the neurologic signs and symptoms caused by the endocrine disorders while managing endocrine disorders. This article provides an overview of the neurologic manifestations found in various endocrine disorders that affect pediatric patients. It is valuable to think about 'endocrine disorder' as a cause of the neurologic manifestations. Early diagnosis and treatment of hormonal imbalance can rapidly relieve the neurologic symptoms. Better understanding of the interaction between the endocrine system and the nervous system, combined with the knowledge about the pathophysiology of the neurologic manifestations presented in the endocrine disorders might allow earlier diagnosis and better treatment of the endocrine disorders. PMID:25654063

  9. Mucocutaneous manifestations of helminth infections: Nematodes.

    PubMed

    Lupi, Omar; Downing, Christopher; Lee, Michael; Pino, Livia; Bravo, Francisco; Giglio, Patricia; Sethi, Aisha; Klaus, Sidney; Sangueza, Omar P; Fuller, Claire; Mendoza, Natalia; Ladizinski, Barry; Woc-Colburn, Laila; Tyring, Stephen K

    2015-12-01

    In the 21st century, despite increased globalization through international travel for business, medical volunteerism, pleasure, and immigration/refugees into the United States, there is little published in the dermatology literature regarding the cutaneous manifestations of helminth infections. Approximately 17% of travelers seek medical care because of cutaneous disorders, many related to infectious etiologies. This review will focus on the cutaneous manifestations of helminth infections and is divided into 2 parts: part I focuses on nematode infections, and part II focuses on trematode and cestode infections. This review highlights the clinical manifestations, transmission, diagnosis, and treatment of helminth infections. Nematodes are roundworms that cause diseases with cutaneous manifestations, such as cutaneous larval migrans, onchocerciasis, filariasis, gnathostomiasis, loiasis, dracunculiasis, strongyloidiasis, ascariasis, streptocerciasis, dirofilariasis, and trichinosis. Tremadotes, also known as flukes, cause schistosomiasis, paragonimiasis, and fascioliasis. Cestodes (tapeworms) are flat, hermaphroditic parasites that cause diseases such as sparganosis, cysticercosis, and echinococcus. PMID:26568337

  10. Musculoskeletal manifestations of the antiphospholipid syndrome.

    PubMed

    Noureldine, M H A; Khamashta, M A; Merashli, M; Sabbouh, T; Hughes, G R V; Uthman, I

    2016-04-01

    The scope of clinical and laboratory manifestations of the antiphospholipid syndrome (APS) has increased dramatically since its discovery in 1983, where any organ system can be involved. Musculoskeletal complications are consistently reported in APS patients, not only causing morbidity and mortality, but also affecting their quality of life. We reviewed all English papers on APS involvement in the musculoskeletal system using Google Scholar and Pubmed; all reports are summarized in a table in this review. The spectrum of manifestations includes arthralgia/arthritis, avascular necrosis of bone, bone marrow necrosis, complex regional pain syndrome type-1, muscle infarction, non-traumatic fractures, and osteoporosis. Some of these manifestations were reported in good quality studies, some of which showed an association between aPL-positivity and the occurrence of these manifestations, while others were merely described in case reports. PMID:26923284

  11. Vortices in stratified protoplanetary disks. From baroclinic instability to vortex layers

    NASA Astrophysics Data System (ADS)

    Barge, P.; Richard, S.; Le Dizès, S.

    2016-08-01

    Context. Large-scale vortices could play a key role in the evolution of protoplanetary disks, particularly in the dead-zone where no turbulence associated with magnetic field is expected. Their possible formation by the subcritical baroclinic instability is a complex issue because of the vertical structure of the disk and the elliptical instability. Aims: In 2D disks the baroclinic instability is studied as a function of the thermal transfer efficiency. In 3D disks we explore the importance of radial and vertical stratification on the processes of vortex formation and amplification. Methods: Numerical simulations are performed using a fully compressible hydrodynamical code based on a second-order finite volume method. We assume a perfect gas law in inviscid disk models in which heat transfer is due to either relaxation or diffusion. Results: In 2D, the baroclinic instability with thermal relaxation leads to the formation of large-scale vortices, which are unstable with respect to the elliptic instability. In the presence of heat diffusion, hollow vortices are formed which evolve into vortical structures with a turbulent core. In 3D, the disk stratification is found to be unstable in a finite layer which can include the mid-plane or not. When the unstable layer contains the mid-plane, the 3D baroclinic instability with thermal relaxation is found to develop first in the unstable layer as in 2D, producing large-scale vortices. These vortices are then stretched out in the stable layer, creating long-lived columnar vortical structures extending through the width of the disk. They are also found to be the source of internal vortex layers that develop across the whole disk along baroclinic critical layer surfaces, and form new vortices in the upper region of the disk. Conclusions: In 3D disks, vortices can survive for a very long time if the production of vorticity by the baroclinic amplification balances the destruction of vorticity by the elliptical instability

  12. Rheumatic Manifestations in Patients with Chikungunya Infection.

    PubMed

    Arroyo-Ávila, Mariangelí; Vilá, Luis M

    2015-06-01

    Chikungunya virus (CHIKV) infection is a common cause of febrile arthritis. The most common manifestations of acute infection are fever, symmetrical polyarthralgias or polyarthritis, myalgias, and maculopapular rash. Up to 80% of patients may develop musculoskeletal manifestations that persist longer than 3 months, causing impairment in their quality of life. The most common chronic manifestations are persistent or relapsing-remitting polyarthralgias, polyarthritis, and myalgias. Fingers, wrists, knees, ankles, and toes are the most frequently involved, but proximal joints and axial involvement can occur in the chronic stage. Chronic manifestations of CHIKV infection may resemble those of some autoimmune connective tissue diseases. Furthermore, CHIKV infection can cause cryoglobulinemia and may induce rheumatoid arthritis and seronegative spondyloarthropathies in genetically susceptible individuals. The Centers for Disease Control and Prevention recommend acetaminophen and non steroidal anti-inflammatory drugs for the acute rheumatic manifestations of CHIKV infection. However, some studies suggest that low-dose corticosteroids for about 1-2 months (depending on clinical course) are beneficial in relieving acute rheumatic symptoms. Conversely, hydroxychloroquine in combination with corticosteroids or other disease modifying anti-rheumatic drugs (DMARDs) has been successful in treating chronic rheumatic manifestations. Methotrexate and sulfasalazine (alone or in combination) have also been effective for chronic CHIKV arthritis. Patients with CHIKV infection should be closely monitored to identify those with chronic arthritis who would benefit from a rheumatologic evaluation and early treatment with DMARDs. PMID:26061056

  13. 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.

  14. Laithwaite's Heavy Spinning Disk Demonstration

    NASA Astrophysics Data System (ADS)

    Cross, Rod

    2014-09-01

    In 1974, Professor Eric Laithwaite demonstrated an unusually heavy gyroscope at a Royal Institution lecture in London. The demonstration was televised and can be viewed on YouTube.1 A recent version of the same experiment, together with partial explanations, attracted two million YouTube views in the first few months.2 In both cases, the gyroscope consisted of a 40-lb (18-kg) spinning disk on the end of a 3-ft (0.91-m) long axle. The most remarkable feature of the demonstration was that Laithwaite was able to lift the disk over his head with one hand, holding onto the far end of the axle. The impression was given that the 40-lb disk was almost weightless, or "as light as a feather" according to Laithwaite.

  15. ALMA observations of protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Hogerheijde, Michiel

    2015-08-01

    The Universe is filled with planetary systems, as recent detections of exo-planets have shown. Such systems grow out of disks of gas and dust that surround newly formed stars. The ground work for our understanding of the structure, composition, and evolution of such disks has been laid with infrared telescopes in the 1980's, 1990's, and 2000's, as well as with millimeter interferometers operating in the United States, France, and Japan. With the construction of the Atacama Large Millimeter / submillimeter Array, a new era of studying planet-forming disks has started. The unprecedented leap in sensitivity and angular resolution that ALMA offers, has truely revolutionized our understanding of disks. No longer featureless objects consisting of gas and smalll dust, they are now seen to harbor a rich structure and chemistry. The ongoing planet-formation process sculpts many disks into systems of rings and arcs; grains grown to millimeter-sizes collect in high-pressure areas where they could grow out to asteroids or comets or further generations of planets. This wealth of new information directly addresses bottlenecks in our theoretical understanding of planet formation, such as the question how grains can grow past the 'meter-sized' barrier or overcome the 'drift barrier', and how gas and ice evolve together and ultimately determine the elemental compositions of both giant and terrestrial planets. I will review the recent ALMA results on protoplanetary disks, presenting results on individual objects and from the first populations studies. I will conclude with a forward look, on what we might expect from ALMA in this area for the years and decades to come.

  16. Incorporating finite element analysis into component life and reliability

    NASA Technical Reports Server (NTRS)

    August, Richard; Zaretsky, Erwin V.

    1991-01-01

    A method for calculating a component's design survivability by incorporating finite element analysis and probabilistic material properties was developed. The method evaluates design parameters through direct comparisons of component survivability expressed in terms of Weibull parameters. The analysis was applied to a rotating disk with mounting bolt holes. The highest probability of failure occurred at, or near, the maximum shear stress region of the bolt holes. Distribution of failure as a function of Weibull slope affects the probability of survival. Where Weibull parameters are unknown for a rotating disk, it may be permissible to assume Weibull parameters, as well as the stress-life exponent, in order to determine the disk speed where the probability of survival is highest.

  17. Disk Chemistry and Cometary Composition

    NASA Astrophysics Data System (ADS)

    Markwick, A. J.; Charnley, S. B.

    2003-05-01

    We will describe current chemical modelling of disks similar to the protosolar nebula. Calculations are being undertaken to determine the spatial and temporal chemistry of the gas and dust within the 5-40AU comet-forming region of the nebula. These theoretical studies aim to determine the contribution of pristine and partially-processed interstellar material from the cool outer nebula, as compared to that obtained from outward radial mixing of matter from the hot inner nebula. Reference Molecular distributions in the inner regions of protostellar disks, Markwick, A. J., Ilgner, M., Millar, T. J., Henning, Th. (2002), Astron. Astrophys., 385, 632.

  18. Disk Chemistry and Cometary Composition

    NASA Astrophysics Data System (ADS)

    Markwick, A. J.; Charnley, S. B.

    2005-01-01

    We will describe current chemical modelling of disks similar to the protosolar nebula. Calculations are being undertaken to determine the spatial and temporal chemistry of the gas and dust within the 5-40AU comet-forming region of the nebula. These theoretical studies aim to determine the contribution of pristine and partially-processed interstellar material from the cool outer nebula as compared to that obtained from outward radial mixing of matter from the hot inner nebula. Reference Molecular distributions in the inner regions of protostellar disks Markwick A. J. Ilgner M. Millar T. J. Henning Th. (2002) Astron. Astrophys. 385 632

  19. Forging Long Shafts On Disks

    NASA Technical Reports Server (NTRS)

    Tilghman, Chris; Askey, William; Hopkins, Steven

    1989-01-01

    Isothermal-forging apparatus produces long shafts integral with disks. Equipment based on modification of conventional isothermal-forging equipment, required stroke cut by more than half. Enables forging of shafts as long as 48 in. (122 cm) on typical modified conventional forging press, otherwise limited to making shafts no longer than 18 in. (46cm). Removable punch, in which forged material cools after plastic deformation, essential novel feature of forging apparatus. Technology used to improve such products as components of gas turbines and turbopumps and of other shaft/disk parts for powerplants, drive trains, or static structures.

  20. Theory of Protostellar Disk Fromation

    NASA Astrophysics Data System (ADS)

    Li, Zhi-Yun

    2015-08-01

    Disk formation, once thought to be a simple consequence of the conservation of angular momentum during the hydrodynamic core collapse, is far more subtle in magnetized gas. In this case, the rotation can be strongly magnetically braked. Indeed, both analytic arguments and numerical simulations have shown that disk formation is suppressed in strict ideal MHD for the observed level of core magnetization. I will discuss the physical reason for this so-called "magnetic braking catastrophe," and review possible resolutions to this problem that have been proposed so far, including non-ideal MHD effects, misalignment between the magnetic field and rotation axis, and especially turbulence.

  1. Semi-analytical solution for the temperature profiles in solid-state laser disks mounted on heat spreaders.

    PubMed

    Hodgson, Norman; Caprara, Andrea

    2016-07-01

    Temperature profiles in pumped solid-state laser disks are generally calculated numerically by using finite-element programs to solve the heat conduction equation in the disk and the heat spreader. Analytical expressions exist for the longitudinal temperature profile in the case of an infinitely thick heat spreader or in the limit of zero thickness of the disk. We are presenting a simplified, semi-analytical method to calculate the three-dimensional temperature profiles for any disk or heat spreader dimensions by solving the heat conduction equation using Hankel transforms. This method allows for straightforward optimization of the cooling properties of heat-sink-mounted solid-state and semiconductor disk lasers. PMID:27409198

  2. The Kozai–Lidov Mechanism in Hydrodynamical Disks. II. Effects of Binary and Disk Parameters

    NASA Astrophysics Data System (ADS)

    Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.

    2015-07-01

    Martin et al. showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions, binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.

  3. The Kozai-Lidov mechanism in hydrodynamical disks. II. Effects of binary and disk parameters

    SciTech Connect

    Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.

    2015-07-01

    Martin et al. (2014b) showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions, binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.

  4. THICK-DISK EVOLUTION INDUCED BY THE GROWTH OF AN EMBEDDED THIN DISK

    SciTech Connect

    Villalobos, Alvaro; Helmi, Amina; Kazantzidis, Stelios E-mail: ahelmi@astro.rug.n E-mail: villalobos@oats.inaf.i

    2010-07-20

    We perform collisionless N-body simulations to investigate the evolution of the structural and kinematical properties of simulated thick disks induced by the growth of an embedded thin disk. The thick disks used in the present study originate from cosmologically common 5:1 encounters between initially thin primary disk galaxies and infalling satellites. The growing thin disks are modeled as static gravitational potentials and we explore a variety of growing-disk parameters that are likely to influence the response of thick disks. We find that the final thick-disk properties depend strongly on the total mass and radial scale length of the growing thin disk, and much less sensitively on its growth timescale and vertical scale height as well as the initial sense of thick-disk rotation. Overall, the growth of an embedded thin disk can cause a substantial contraction in both the radial and vertical direction, resulting in a significant decrease in the scale lengths and scale heights of thick disks. Kinematically, a growing thin disk can induce a notable increase in the mean rotation and velocity dispersions of thick-disk stars. We conclude that the reformation of a thin disk via gas accretion may play a significant role in setting the structure and kinematics of thick disks, and thus it is an important ingredient in models of thick-disk formation.

  5. Extra-articular Manifestations in Rheumatoid Arthritis

    PubMed Central

    Cojocaru, Manole; Cojocaru, Inimioara Mihaela; Silosi, Isabela; Vrabie, Camelia Doina; Tanasescu, R

    2010-01-01

    ABSTRACT Rheumatoid arthritis (RA) is a systemic autoimmune disease whose main characteristic is persistent joint inflammation that results in joint damage and loss of function. Although RA is more common in females, extra-articular manifestations of the disease are more common in males. The extra-articular manifestations of RA can occur at any age after onset. It is characterised by destructive polyarthritis and extra-articular organ involvement, including the skin, eye, heart, lung, renal, nervous and gastrointestinal systems. The frequence of extra-articular manifestations in RA differs from one country to another. Extra-articular organ involvement in RA is more frequently seen in patients with severe, active disease and is associated with increased mortality. Incidence and frequence figures for extra-articular RA vary according to study design. Extra-articular involvement is more likely in those who have RF and/or are HLA-DR4 positive. Occasionally, there are also systemic manifestations such as vasculitis, visceral nodules, Sjögren's syndrome, or pulmonary fibrosis present. Nodules are the most common extra-articular feature, and are present in up to 30%; many of the other classic features occur in 1% or less in normal clinic settings. Sjögren's syndrome, anaemia of chronic disease and pulmonary manifestations are relatively common – in 6-10%, are frequently present in early disease and are all related to worse outcomes measures of rheumatoid disease in particular functional impairment and mortality. The occurrence of these systemic manifestations is a major predictor of mortality in patients with RA. This paper focuses on extra-articular manifestations, defined as diseases and symptoms not directly related to the locomotor system. PMID:21977172

  6. Manifestly scale-invariant regularization and quantum effective operators

    NASA Astrophysics Data System (ADS)

    Ghilencea, D. M.

    2016-05-01

    Scale-invariant theories are often used to address the hierarchy problem. However the regularization of their quantum corrections introduces a dimensionful coupling (dimensional regularization) or scale (Pauli-Villars, etc) which breaks this symmetry explicitly. We show how to avoid this problem and study the implications of a manifestly scale-invariant regularization in (classical) scale-invariant theories. We use a dilaton-dependent subtraction function μ (σ ) which, after spontaneous breaking of the scale symmetry, generates the usual dimensional regularization subtraction scale μ (⟨σ ⟩) . One consequence is that "evanescent" interactions generated by scale invariance of the action in d =4 -2 ɛ (but vanishing in d =4 ) give rise to new, finite quantum corrections. We find a (finite) correction Δ U (ϕ ,σ ) to the one-loop scalar potential for ϕ and σ , beyond the Coleman-Weinberg term. Δ U is due to an evanescent correction (∝ɛ ) to the field-dependent masses (of the states in the loop) which multiplies the pole (∝1 /ɛ ) of the momentum integral to give a finite quantum result. Δ U contains a nonpolynomial operator ˜ϕ6/σ2 of known coefficient and is independent of the subtraction dimensionless parameter. A more general μ (ϕ ,σ ) is ruled out since, in their classical decoupling limit, the visible sector (of the Higgs ϕ ) and hidden sector (dilaton σ ) still interact at the quantum level; thus, the subtraction function must depend on the dilaton only, μ ˜σ . The method is useful in models where preserving scale symmetry at quantum level is important.

  7. Molecular Line Observations of Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Chapillon, Edwige; Dutrey, Anne; Henning, Thomas; Guilloteau, Stephane; Wakelam, Valentine; Hersant, Franck; Gueth, Frédéric; Piétu, Vincent; Ohashi, Nagayoshi; Boehler, Yann; Launhardt, Ralf; Semenov, Dimitry; Schreyer, Katharina; Guélin, Michel; Parise, Bérengère

    2013-07-01

    We summarize in this poster a long-term study of the chemistry as a powerful tool to constrain the protoplanetary disk physics. Most of the above results were obtained in the frame of the CID (Chemistry In Disks) consortium.

  8. Herniated Disk in the Lower Back

    MedlinePlus

    ... lives. A high percentage of people will have low back and leg pain caused by a herniated disk. Although a herniated ... pressure against the outer ring may cause lower back pain. If the disk is very worn or injured, ...

  9. Optical Digital Disks as Mass Storage Media.

    ERIC Educational Resources Information Center

    Boss, Richard W.

    1983-01-01

    Describes the optical digital disk, which stores machine-readable information in digitized form, and discusses their production, cost, present and future applications. The major companies currently active in the disk field are noted. (MBR)

  10. Electronic Teaching: Hard Disks and Networks.

    ERIC Educational Resources Information Center

    Howe, Samuel F.

    1984-01-01

    Describes floppy-disk and hard-disk based networks, electronic systems linking microcomputers together for the purpose of sharing peripheral devices, and presents points to remember when shopping for a network. (MBR)

  11. QUARKONIUM AT FINITE TEMPERATURE.

    SciTech Connect

    UMEDA, T.

    2006-06-09

    Lattice QCD studies on charmonium at finite temperature are presented After a discussion about problems for the Maximum Entropy Method applied to finite temperature lattice QCD, I show several results on charmonium spectral functions. The 'wave function' of charmonium is also discussed to study the spatial correlation between quark and anti-quark in deconfinement phase.

  12. Numerical Simulations of a Flexible Disk Rotating Close to a Rigid Rotating Wall

    NASA Astrophysics Data System (ADS)

    Gad, Abdelrasoul M. M.; Rhim, Yoon-Chul

    2008-07-01

    In this paper, we present a numerical study about the dynamics of a flexible disk rotating close to a rigid rotating wall. Two new types of flat stabilizers, co-rotating and counter-rotating flat stabilizers, are introduced besides the well-known fixed-stabilizer type which has been studied extensively. The disk is modeled using linear plate theory and the air flow between the flexible disk and the rigid wall is modeled using Navier-Stokes and continuity equations. The flow equations are discretized using finite volume method (FVM) and solved numerically with semi-implicit method for pressure-linked equations (SIMPLE) algorithm, while the spatial terms in the disk model are discretized using finite difference method (FDM) and time integration is performed using fourth-order Runge-Kutta method. The transient numerical simulation is performed to compare the stability boundaries of the different types of flat-stabilizer at a wide range of circumferential mode numbers. The numerical results showed an improved stability of the flexible disk when rotating close to a counter-rotating flat-stabilizer compared with co-rotating and fixed flat-stabilizers.

  13. Turbulent Mixing Chemistry in Disks

    NASA Astrophysics Data System (ADS)

    Semenov, D.; Wiebe, D.

    2006-11-01

    A gas-grain chemical model with surface reaction and 1D/2D turbulent mixing is available for protoplanetary disks and molecular clouds. Current version is based on the updated UMIST'95 database with gas-grain interactions (accretion, desorption, photoevaporation, etc.) and modified rate equation approach to surface chemistry (see also abstract for the static chemistry code).

  14. Accretion disks around black holes

    NASA Technical Reports Server (NTRS)

    Abramowicz, M. A.

    1994-01-01

    The physics of accretion flow very close to a black hole is dominated by several general relativistic effects. It cannot be described by the standard Shakura Sunyaev model or by its relativistic version developed by Novikov and Thome. The most important of these effects is a dynamical mass loss from the inner edge of the disk (Roche lobe overflow). The relativistic Roche lobe overflow induces a strong advective cooling, which is sufficient to stabilize local, axially symmetric thermal and viscous modes. It also stabilizes the non-axially-symmetric global modes discovered by Papaloizou and Pringle. The Roche lobe overflow, however, destabilizes sufficiently self-gravitating accretion disks with respect to a catastrophic runaway of mass due to minute changes of the gravitational field induced by the changes in the mass and angular momentum of the central black hole. One of the two acoustic modes may become trapped near the inner edge of the disk. All these effects, absent in the standard model, have dramatic implications for time-dependent behavior of the accretion disks around black holes.

  15. Deuterium chemistry in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Albertsson, T.; Semenov, D.; Henning, T.

    2011-05-01

    We have generated a extensive chemical network that includes reactions with multi-deuterated species, in which the most recent information deuterium chemistry is implemented. By implementing this chemical network with our sophisticated model, we study in detail the chemical evolution of protoplanetary disks, and compare our results with observations.

  16. Circumnuclear Keplerian Disks in Galaxies

    NASA Astrophysics Data System (ADS)

    Bertola, Francesco; Cappellari, Michele; Funes, S. J., José G.; Corsini, Enrico M.; Pizzella, Alessandro; Beltrán, Juan C. Vega

    1998-12-01

    In this Letter, we demonstrate the possibility of inferring the presence of Keplerian gaseous disks using properly equipped optical ground-based telescopes. We have modeled the peculiar bidimensional shape of the emission lines in a sample of five early-type disk galaxies as due to the motion of a gaseous disk rotating in the combined potential of a central pointlike mass and of an extended stellar disk. The value of the central mass concentration estimated for four galaxies of the sample (NGC 2179, NGC 4343, NGC 4435, and NGC 4459) is ~109 Msolar. This value, according to the assumptions made in our model, is overestimated. However, we have calculated that the effect is well within the errors. For the remaining galaxy, NGC 5064, an upper limit of 5×107 Msolar is estimated. Based on observations carried out at ESO, La Silla, (Chile) (ESO N. 58, A-0564) and at the Mount Graham International Observatory (AZ) with the VATT: the Alice P. Lennon Telescope and the Thomas J. Bannan Astrophysics Facility.

  17. Spaceflight optical disk recorder development

    NASA Technical Reports Server (NTRS)

    Jurczyk, Stephen G.; Hines, Glenn D.; Shull, Thomas A.

    1992-01-01

    Mass memory systems based on rewriteable optical disk media are expected to play an important role in meeting the data system requirements for future NASA spaceflight missions. NASA has established a program to develop a high performance (high rate, large capacity) optical disk recorder focused on use aboard unmanned Earth orbiting platforms. An expandable, adaptable system concept is proposed based on disk drive modules and a modular controller. Drive performance goals are 10 gigabyte capacity, 300 megabit/s transfer rate, 10 exp -12 corrected bit error rate, and 150 millisec access time. This performance is achieved by writing eight data tracks in parallel on both sides of a 14 in. optical disk using two independent heads. System goals are 160 gigabyte capacity, 1.2 gigabits/s data rate with concurrent I/O, 250 millisec access time, and two to five year operating life on orbit. The system can be configured to meet various applications. This versatility is provided by the controller. The controller provides command processing, multiple drive synchronization, data buffering, basic file management, error processing, and status reporting. Technology developments, design concepts, current status including a computer model of the system and a Controller breadboard, and future plans for the Drive and Controller are presented.

  18. VORTEX MIGRATION IN PROTOPLANETARY DISKS

    SciTech Connect

    Paardekooper, Sijme-Jan; Lesur, Geoffroy; Papaloizou, John C. B.

    2010-12-10

    We consider the radial migration of vortices in two-dimensional isothermal gaseous disks. We find that a vortex core, orbiting at the local gas velocity, induces velocity perturbations that propagate away from the vortex as density waves. The resulting spiral wave pattern is reminiscent of an embedded planet. There are two main causes for asymmetries in these wakes: geometrical effects tend to favor the outer wave, while a radial vortensity gradient leads to an asymmetric vortex core, which favors the wave at the side that has the lowest density. In the case of asymmetric waves, which we always find except for a disk of constant pressure, there is a net exchange of angular momentum between the vortex and the surrounding disk, which leads to orbital migration of the vortex. Numerical hydrodynamical simulations show that this migration can be very rapid, on a timescale of a few thousand orbits, for vortices with a size comparable to the scale height of the disk. We discuss the possible effects of vortex migration on planet formation scenarios.

  19. Pulmonary manifestations of renal cell carcinoma.

    PubMed

    Agrawal, Abhinav; Sahni, Sonu; Iftikhar, Asma; Talwar, Arunabh

    2015-12-01

    Renal cell carcinoma (RCC) accounts for majority of all primary renal neoplasms. Classic manifestations of RCC include the triad of flank pain, hematuria and a palpable renal mass. Patients with RCC can develop various extra renal manifestations including involvements of the lungs, inferior vena cava, liver and the bones. The pulmonary manifestations of renal cell carcinoma include metastatic disease including endobronchial, pleural, parenchymal or lymph node metastasis, pleural effusion or hemothorax. Pulmonary embolism and tumor embolism is another common manifestation of renal cell carcinoma. RCC is a highly vascular tumor and can cause pulmonary arterio-venous fistulas leading to high output failure. Rarely, RCC can also present with paraneoplastic presentations including cough or bilateral diaphragm paralysis. Drugs used to treat RCC have been associated with drug related pneumonitis and form an important differential diagnosis in patients with RCC on therapy presenting with shortness of breath. In this review we discuss the various pulmonary manifestations of RCC. A high index of suspicion with these presentations can lead to an early diagnosis and assist in instituting an appropriate intervention. PMID:26525375

  20. TURBULENT DISKS ARE NEVER STABLE: FRAGMENTATION AND TURBULENCE-PROMOTED PLANET FORMATION

    SciTech Connect

    Hopkins, Philip F.; Christiansen, Jessie L.

    2013-10-10

    A fundamental assumption in our understanding of disks is that when the Toomre Q >> 1, the disk is stable against fragmentation into self-gravitating objects (and so cannot form planets via direct collapse). But if disks are turbulent, this neglects a spectrum of stochastic density fluctuations that can produce rare, high-density mass concentrations. Here, we use a recently developed analytic framework to predict the statistics of these fluctuations, i.e., the rate of fragmentation and mass spectrum of fragments formed in a turbulent Keplerian disk. Turbulent disks are never completely stable: we calculate the (always finite) probability of forming self-gravitating structures via stochastic turbulent density fluctuations in such disks. Modest sub-sonic turbulence above Mach number M∼0.1 can produce a few stochastic fragmentation or 'direct collapse' events over ∼Myr timescales, even if Q >> 1 and cooling is slow (t{sub cool} >> t{sub orbit}). In transsonic turbulence this extends to Q ∼ 100. We derive the true Q-criterion needed to suppress such events, which scales exponentially with Mach number. We specify to turbulence driven by magneto-rotational instability, convection, or spiral waves and derive equivalent criteria in terms of Q and the cooling time. Cooling times ∼> 50 t{sub dyn} may be required to completely suppress fragmentation. These gravo-turbulent events produce mass spectra peaked near ∼(Q M{sub disk}/M{sub *}){sup 2} M{sub disk} (rocky-to-giant planet masses, increasing with distance from the star). We apply this to protoplanetary disk models and show that even minimum-mass solar nebulae could experience stochastic collapse events, provided a source of turbulence.

  1. Optimization of the Processing of Mo Disks

    SciTech Connect

    Tkac, Peter; Rotsch, David A.; Stepinski, Dominique; Makarashvili, Vakhtang; Harvey, James; Vandegrift, George F.

    2016-01-01

    The objective of this work is to decrease the processing time for irradiated disks of enriched Mo for the production of 99Mo. Results are given for the dissolution of nonirradiated Mo disks, optimization of the process for large-scale dissolution of sintered disks, optimization of the removal of the main side products (Zr and Nb) from dissolved targets, and dissolution of irradiated Mo disks.

  2. Fabrication of Large YBCO Superconducting Disks

    NASA Technical Reports Server (NTRS)

    Koczor, Ronald J.; Noever, David A.; Robertson, Glen A.

    1999-01-01

    We have undertaken fabrication of large bulk items to develop a repeatable process and to provide test articles in laboratory experiments investigating reported coupling of electromagnetic fields with the local gravity field in the presence of rotating superconducting disks. A successful process was developed which resulted in fabrication of 30 cm diameter annular disks. The disks were fabricated of the superconductor YBa2Cu3O(7-x). Various material parameters of the disks were measured.

  3. Planet Masses from Disk Spirals

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-12-01

    Young, forming planets can generate immense spiral structures within their protoplanetary disks. A recent study has shown that observations of these spiral structures may allow astronomers to measure the mass of the planets that create them.Spirals From WavesSnapshots of the surface density of a protoplanetary disk in a 2D simulation, 3D simulation, and synthesized scattered-light image. Click for a closer look! [Fung Dong, 2015]Recent studies have shown that a single planet, if it is massive enough, can excite multiple density waves within a protoplanetary disk as it orbits. These density waves can then interfere to produce a multiple-armed spiral structure in the disk inside of the planets orbit a structure which can potentially be observed in scattered-light images of the disk.But what do these arms look like, and what factors determine their structure? In a recently published study, Jeffrey Fung and Ruobing Dong, two researchers at the University of California at Berkeley, have modeled the spiral arms in an effort to answer these questions.Arms Provide AnswersA useful parameter for describing the structure is the azimuthal separation (sep) between the primary and secondary spiral arms. If you draw a circle within the disk and measure the angle between the two points where the primary and secondary arms cross it, thats sep.Azimuthal separation of the primary and secondary spiral arms, as a function of the planet-to-star mass ratio q. The different curves represent different disk aspect ratios. [Fung Dong, 2015]The authors find thatsep stays roughly constant for different radii, but its strongly dependent on the planets mass: for larger planets, sep increases. They discover that sep scales as a power of the planet mass for companions between Neptune mass and 16 Jupiter masses, orbiting around a solar-mass star. For larger, brown-dwarf-size companions, sep is a constant 180.If this new theory is confirmed, it could have very interesting implications for

  4. Warps and Streams --- Pushing and lifting material out of the midplane from galactic and circumstellar disks

    NASA Astrophysics Data System (ADS)

    Quillen, Alice C.

    2016-05-01

    Sub-structures such as warps and streams in the vertical distribution of gas and dust can manifest as spiral shaped structures, twists in the velocity field, vertical streaming motions, X-shapes, and quasiperiodic dips in light curves. I will review and contrast physical mechanisms for lifting material out of the mid-plane in galactic and circumstellar disks including instabilities, resonant mechanisms and tidal excitations.

  5. PSOCT studies of intervertebral disk

    NASA Astrophysics Data System (ADS)

    Matcher, Stephen J.; Winlove, Peter C.; Gangnus, Sergey V.

    2004-07-01

    Polarization-sensitive optical coherence tomography (PSOCT) is an emerging optical imaging technique that is sensitive to the birefringence properties of tissues. It thus has applications in studying the large-scale ordering of collagen fibers within connective tissues. This ordering not only provides useful insights into the relationship between structure and function for various anatomical structures but also is an indicator of pathology. Intervertebral disk is an elastic tissue of the spine and possesses a 3-D collagen structure well suited to study using PSOCT. Since the outer layer of the disk has a lamellar structure with collagen fibers oriented in a trellis-like arrangement between lamellae, the birefringence fast-axis shows pronounced variations with depth, on a spatial scale of about 100 μm. The lamellar thickness varies with age and possibly with disease. We have used a polarisation-sensitive optical coherence tomography system to measure the birefringence properties of freshly excised, hydrated bovine caudal intervertebral disk and compared this with equine flexor tendon. Our results clearly demonstrate the ability of PSOCT to detect the outer three lamellae, down to a depth of at least 700 μm, via discontinuities in the depth-resolved retardance. We have applied a simple semi-empirical model based on Jones calculus to quantify the variation in the fast-axis orientation with depth. Our data and modeling is in broad agreement with previous studies using x-ray diffraction and polarization microscopy applied to histological sections of dehydrated disk. Our results imply that PSOCT may prove a useful tool to study collagen organisation within intervertebral disk in vitro and possibly in vivo and its variation with age and disease.

  6. Optimizing a tandem disk model

    SciTech Connect

    Healey, J.V.

    1983-07-01

    A very simple physicomathematical model, in which thin straight blades with zero drag skim across a plane rectangular disk, shows that the maximum power coefficient attains the classical maximum of 0.593 over a range of T and a zero or small negative value of alpha/sub 0/. This maximum appears independent of sigma and there are values of T and alpha/sub 0/ for which the speed through the disk becomes complex and the model breaks down. Extending this model to a tandem disk system leads to a difficulty in defining the power coefficient. Attempts to optimize the system output based on reference areas A/sub 1/, A/sub 2/, and A/sub 4/ prove futile and the sum of the coefficients is chosen for this purpose. For thin blades and zero drag the analytic solution is available and it shows that the maximum value of 2 X 0.593 is attained over a narrow range of slightly negative alpha/sub 0/ (blade nose in) and medium values of T. The maximum is independent of sigma. As T is increased, the model breaks down either after C /SUB psum/ becomes large and negative or after backflow through the downwind disk occurs. There appears to be no requirement on load distribution between the disks. By comparison, modeling a machine with NACA 0012 blades at Re = 1.34 X 10/sup 6/ shows that the maximum value of C /SUB psum/ depends on the solidity. For example, at sigma = 0.4, the maximum value of C /SUB psum/ is 83% of 2 X 0.593. At such high values of sigma, however, the ranges of alpha/sub 0/ and T over which solutions are available become very limited.

  7. Accretion disk viscosity and internal waves in disks

    NASA Astrophysics Data System (ADS)

    Huang, Min

    1992-01-01

    Recently, Vishniac, Jin and Diamond suggested that internal waves in accretion disks play a critical role in generating magnetic fields, and consequently are indirectly responsible for angular momentum transfer in thin, conducting, and non-self-gravitational disk systems. A project in which we will construct a quantitative model of the internal wave spectrum in accretion disks is started. It includes two aspects of work. The physical properties of the waves in a thin, non-self-gravitational, and non-magnetized accretion disk with realistic vertical structure is cataloged and examined. Besides the low frequency internal waves discovered by Vishniac and Diamond, it was found that sound waves with low frequency and low axisymmetry (with small absolute value of m) are capable of a driving dynamo because they are (1) well confined in a layer with thickness 2(absolute value of m)H where H is the disk scale height; (2) highly dispersive so they may survive the strong dissipation caused by the coherent nonlinear interaction their high frequency partners experience; and (3) elliptically polarized because they are confined in the z-direction. As a first step towards constructing a quantitative theory of this dynamo effect, a framework of calculating resonant nonlinear interaction among waves in disk is established. We are developing a numerical code which will compute the steady spectrum of the wave field in this framework. For simplicity, we only include the low frequency internal waves suggested by Vishniac and Diamond in the present stage. In the vicinity of the static state, the time step whose length is determined by the evolution of the modes with the largest amplitudes is too large for the modes with smaller amplitudes and overshooting occurs. Through nonlinear coupling, this overshooting is amplified and appears as a numerical instability affecting the evolution of the large amplitude modes. Shorter time steps may delay the appearance of the instability but not cure

  8. Circumstellar Debris Disks: Diagnosing the Unseen Perturber

    NASA Astrophysics Data System (ADS)

    Nesvold, Erika R.; Naoz, Smadar; Vican, Laura; Farr, Will M.

    2016-07-01

    The first indication of the presence of a circumstellar debris disk is usually the detection of excess infrared emission from the population of small dust grains orbiting the star. This dust is short-lived, requiring continual replenishment, and indicating that the disk must be excited by an unseen perturber. Previous theoretical studies have demonstrated that an eccentric planet orbiting interior to the disk will stir the larger bodies in the belt and produce dust via interparticle collisions. However, motivated by recent observations, we explore another possible mechanism for heating a debris disk: a stellar-mass perturber orbiting exterior to and inclined to the disk and exciting the disk particles’ eccentricities and inclinations via the Kozai–Lidov mechanism. We explore the consequences of an exterior perturber on the evolution of a debris disk using secular analysis and collisional N-body simulations. We demonstrate that a Kozai–Lidov excited disk can generate a dust disk via collisions and we compare the results of the Kozai–Lidov excited disk with a simulated disk perturbed by an interior eccentric planet. Finally, we propose two observational tests of a dust disk that can distinguish whether the dust was produced by an exterior brown dwarf or stellar companion or an interior eccentric planet.

  9. Optical Disk Formats: A Briefing. ERIC Digest.

    ERIC Educational Resources Information Center

    Schamber, Linda

    This digest begins with a brief description and review of the development of optical disks. Optical disk formats are then described by capability: Read Only Memory (ROM), Write Once, Read Many (WORM), Interactive (I), and Erasable (E); forms of information (audio, text or data, video or graphics, or a combination); and disk size (most often 12 or…

  10. Microporous Carbon Disks For Sorption Refrigerators

    NASA Technical Reports Server (NTRS)

    Munukutla, Lakshmi V.; Moore, Mark R.

    1993-01-01

    Slow, carefully controlled pyrolysis found to turn polyvinylidene chloride disks into carbon disks having small pores and large surface areas. Disks exhibit high adsorptivities making them useful in krypton-sorption refrigerators. Carbons made from polyvinylidene chloride have greater adsorptive capacities. Thermal instability controlled and variability of product reduced by careful control of rates of heating, heating times, and rate of final cooling.

  11. PROTOPLANETARY DISK RESONANCES AND TYPE I MIGRATION

    SciTech Connect

    Tsang, David

    2011-11-10

    Waves reflected by the inner edge of a protoplanetary disk are shown to significantly modify Type I migration, even allowing the trapping of planets near the inner disk edge for small planets in a range of disk parameters. This may inform the distribution of planets close to their central stars, as observed recently by the Kepler mission.

  12. Basics of Videodisc and Optical Disk Technology.

    ERIC Educational Resources Information Center

    Paris, Judith

    1983-01-01

    Outlines basic videodisc and optical disk technology describing both optical and capacitance videodisc technology. Optical disk technology is defined as a mass digital image and data storage device and briefly compared with other information storage media including magnetic tape and microforms. The future of videodisc and optical disk is…

  13. Cutaneous manifestations of systemic lupus erythematosus.

    PubMed

    Uva, Luís; Miguel, Diana; Pinheiro, Catarina; Freitas, João Pedro; Marques Gomes, Manuel; Filipe, Paulo

    2012-01-01

    Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease of unknown etiology with many clinical manifestations. The skin is one of the target organs most variably affected by the disease. The American College of Rheumatology (ACR) established 11 criteria as a classificatory instrument to operationalise the definition of SLE in clinical trials. They were not intended to be used to diagnose individuals and do not do well in that capacity. Cutaneous lesions account for four of these 11 revised criteria of SLE. Skin lesions in patients with lupus may be specific or nonspecific. This paper covers the SLE-specific cutaneous changes: malar rash, discoid rash, photosensitivity, and oral mucosal lesions as well as SLE nonspecific skin manifestations, their pathophysiology, and management. A deeper thorough understanding of the cutaneous manifestations of SLE is essential for diagnosis, prognosis, and efficient management. Thus, dermatologists should cooperate with other specialties to provide optimal care of SLE patient. PMID:22888407

  14. Cutaneous Manifestations of Systemic Lupus Erythematosus

    PubMed Central

    Uva, Luís; Miguel, Diana; Pinheiro, Catarina; Freitas, João Pedro; Marques Gomes, Manuel; Filipe, Paulo

    2012-01-01

    Systemic lupus erythematosus (SLE) is a multiorgan autoimmune disease of unknown etiology with many clinical manifestations. The skin is one of the target organs most variably affected by the disease. The American College of Rheumatology (ACR) established 11 criteria as a classificatory instrument to operationalise the definition of SLE in clinical trials. They were not intended to be used to diagnose individuals and do not do well in that capacity. Cutaneous lesions account for four of these 11 revised criteria of SLE. Skin lesions in patients with lupus may be specific or nonspecific. This paper covers the SLE-specific cutaneous changes: malar rash, discoid rash, photosensitivity, and oral mucosal lesions as well as SLE nonspecific skin manifestations, their pathophysiology, and management. A deeper thorough understanding of the cutaneous manifestations of SLE is essential for diagnosis, prognosis, and efficient management. Thus, dermatologists should cooperate with other specialties to provide optimal care of SLE patient. PMID:22888407

  15. [Pulmonary manifestations in systemic lupus erythematosus].

    PubMed

    Vincze, Krisztina; Odler, Balázs; Müller, Veronika

    2016-07-01

    Systemic lupus erythematosus is the most common connective tissue disease that is associated with pulmonary manifestations. Although lupus has the potential to affect any organ, lung involvement is observed during the course of the disease in most cases and it is prognostic for outcome. Pulmonary manifestations in lupus can be classified into five groups based on the anatomical involvement: pleura, lung parenchyma, bronchi and bronchioli, lung vasculature and respiratory muscles can be involved. The most common respiratory manifestations attributable to lupus are pleuritis with or without pleural effusion, pulmonary vascular disease, upper and lower airway dysfunction, parenchymal disease, and diaphragmatic dysfunction (shrinking lung syndrome). In this article the authors summarize lung involvement of lupus, its diagnosis, therapy and prognosis. Orv. Hetil., 2016, 157(29), 1154-1160. PMID:27426464

  16. [Neurological manifestations of giant cell arteritis].

    PubMed

    Grachev, Yu V

    2016-01-01

    The article describes clinical, including neurological manifestations, of giant cell arteritis (GCA) - granulomatous vasculitis of large and medium-sized vessels, predominantly craniofacial, including precerebral and cerebral, arteries. Histopathological features of GCA are illustrated by the schemes of panarteritis and «postarteritis» (proliferative and fibrotic changes in the intima, underlying the development of cerebrovascular disorders). The main clinical manifestations of GCA are described as 3 groups of symptoms: general constitutional symptoms; manifestations of vasculitis of craniofacial, precerebral and cerebral arteries; polymyalgia rheumaticа. The authors present their own version of the taxonomy of visual disturbances in patients with GCA. Diagnostic steps in patients with suggestive signs of GCA are described. Therapeutic regimens of use of glucocorticoids for suggestion/diagnosis of GCA are presented. PMID:26977631

  17. Vertigo as a Predominant Manifestation of Neurosarcoidosis

    PubMed Central

    Imran, Tasnim F.; Eyzner, Igor; Mirani, Neena; Hossain, Tanzib; Fede, Robert; Capitle, Eugenio

    2015-01-01

    Sarcoidosis is a granulomatous disease of unknown etiology that affects multiple organ systems. Neurological manifestations of sarcoidosis are less common and can include cranial neuropathies and intracranial lesions. We report the case of a 21-year-old man who presented with vertigo and uveitis. Extensive workup including brain imaging revealed enhancing focal lesions. A lacrimal gland biopsy confirmed the diagnosis of sarcoidosis. The patient was initially treated with prednisone, which did not adequately control his symptoms, and then was switched to methotrexate with moderate symptomatic improvement. Our patient had an atypical presentation with vertigo as the predominant manifestation of sarcoidosis. Patients with neurosarcoidosis typically present with systemic involvement of sarcoidosis followed by neurologic involvement. Vertigo is rarely reported as an initial manifestation. This case highlights the importance of consideration of neurosarcoidosis as an entity even in patients that may not have a typical presentation or systemic involvement of disease. PMID:25922606

  18. Rheumatologic manifestations of primary immunodeficiency diseases.

    PubMed

    Dimitriades, V R; Sorensen, R

    2016-04-01

    In the last 5 years, several hundred articles have been published concerning the link between primary immunodeficiency disease (PID) and rheumatologic diseases. Although rheumatologic complications were originally thought to be at the opposite ends of the spectrum of immunopathologic manifestations, they are now all being considered secondary manifestations of a causative primary "immune derangement." For the rheumatologist, it is important to be able to identify patients who may present with typical rheumatologic findings but who have an underlying PID. In a systematic manner, this overview addresses both the systemic and organ-based rheumatologic diseases which have known associations with primary immunodeficiencies, and explores how immunodeficiency may actually cause these clinical manifestations. PMID:26971790

  19. Segmentally structured disk triboelectric nanogenerator for harvesting rotational mechanical energy.

    PubMed

    Lin, Long; Wang, Sihong; Xie, Yannan; Jing, Qingshen; Niu, Simiao; Hu, Youfan; Wang, Zhong Lin

    2013-06-12

    We introduce an innovative design of a disk triboelectric nanogenerator (TENG) with segmental structures for harvesting rotational mechanical energy. Based on a cyclic in-plane charge separation between the segments that have distinct triboelectric polarities, the disk TENG generates electricity with unique characteristics, which have been studied by conjunction of experimental results with finite element calculations. The role played by the segmentation number is studied for maximizing output. A distinct relationship between the rotation speed and the electrical output has been thoroughly investigated, which not only shows power enhancement at high speed but also illuminates its potential application as a self-powered angular speed sensor. Owing to the nonintermittent and ultrafast rotation-induced charge transfer, the disk TENG has been demonstrated as an efficient power source for instantaneously or even continuously driving electronic devices and/or charging an energy storage unit. This work presents a novel working mode of TENGs and opens up many potential applications of nanogenerators for harvesting even large-scale energy. PMID:23656350

  20. The SFR and IMF of the galactic disk

    NASA Astrophysics Data System (ADS)

    Just, Andreas

    2003-04-01

    There is a long term dynamical heating of stellar populations with age observed in the age velocity dispersion relation (AVR). This effect allows a determination of the star formation history SFR(t) from local kinematical data of main sequence stars. Using a self-consistent disk model for the vertical structure of the disk, we find from the kinematics of the stars in the solar neighbourhood that the SFR shows a moderate star burst about 10 Gyr ago followed by a continuous decline to the present day value consistent with the observed number of OB stars. The gravitational potential of the gas component and of the Dark Matter Halo is included and the effect of chemical enrichment, finite lifetime of the stars and mass loss of the stellar component are taken into account. The scale heights for main sequence stars together with the SFR is then used to determine constistently the IMF from the observed local luminosity function. The main new result is that the power law break in the present day mass function (PDMF) around 1 M ⊙ is entirely due to evolutionary effects of the disk and does not appear in the IMF.

  1. Self-sustained radial oscillating flows between parallel disks

    NASA Astrophysics Data System (ADS)

    Mochizuki, S.; Yang, W.-J.

    1985-05-01

    It is pointed out that radial flow between parallel circular disks is of interest in a number of physical systems such as hydrostatic air bearings, radial diffusers, and VTOL aircraft with centrally located downward-positioned jets. The present investigation is concerned with the problem of instability in radial flow between parallel disks. A time-dependent numerical study and experiments are conducted. Both approaches reveal the nucleation, growth, migration, and decay of annular separation bubbles (i.e. vortex or recirculation zones) in the laminar-flow region. A finite-difference technique is utilized to solve the full unsteady vorticity transport equation in the theoretical procedure, while the flow patterns in the experiments are visualized with the aid of dye-injection, hydrogen-bubble, and paraffin-mist methods. It is found that the separation and reattachment of shear layers in the radial flow through parallel disks are unsteady phenomena. The sequence of nucleation, growth, migration, and decay of the vortices is self-sustained.

  2. Sedimentation dynamics of disks in a linearly stratified fluid

    NASA Astrophysics Data System (ADS)

    Mercier, Matthieu; Pemeja, Justin; Ern, Patricia

    2014-11-01

    The settling dynamics of small objects in a stratified fluid is important to understand the fate of the biomass in lakes or oceanic environments, for industrial applications such as waste-water disposal for instance. Recent numerical and theoretical studies dedicated to freely falling (or rising) bodies in stratified environments have shown some important differences compared to the same problem in a homogeneous fluid. Experimental results are still needed for validation, especially at low and moderate values of the Reynolds number, Re = Ud / ν <= 100 , with U the instantaneous vertical velocity of the object, d its characteristic length, and ν the kinematic velocity of the fluid. We present original experimental results of freely falling disks of finite thickness in a linearly stratified fluid. Three-dimensional trajectories and the wake of the object are obtained using a pair of cameras visualizing two perpendicular planes, revealing a strong influence of the stratification on the dynamics of the object. In particular, the stratification enhances the steady drag experienced by the disks when falling broadside; and generates a change of stability for the disk orientation (from horizontal to vertical) when the Re number decreases below a threshold value.

  3. The dynamics of particle disks. II - Effects of spin degrees of freedom

    NASA Technical Reports Server (NTRS)

    Araki, Suguru

    1988-01-01

    The present treatment of the thermal equilibria of differentially-rotating, axisymmetric disks consisting of identical, spin-possessing as well as translational DOF-possessing hard sphere particles characterizes these disks' dynamics by means of two novel parameters: (1) the tangential restitution coefficient, and (2) the dimensionless moment of inertia. It is established that rings composed of spinning particles can generally be thermally balanced within more restricted ranges of the optical depth, as well as at higher values of the normal restitution coefficient, than spinless rings. Mean spin is indefinite in the present framework of neglected finite particle-size effects.

  4. Disk-planet interactions: Implications for planetary systems formation and evolution.

    NASA Astrophysics Data System (ADS)

    Ward, Wm. R.

    2000-10-01

    The coherent wavelike response of disk systems to perturbations from nearby or embedded gravitating objects is a subject of vigorous study. The internal disk forces accounting for the organized behavior can be either pressure (resulting in acoustic or short waves) or self-gravity (producing gravity or long waves). In addition to their well-known applications to stellar and planetary ring systems, wave phenomena have relevance to protoplanet interactions with their precursor gaseous nebula and with any residual planetesimal disk. The disk exchanges angular momentum with a perturber via resonant torques. In the absence of collective behavior, only a thin annulus of disk material at each resonance participates in the exchange and can saturate quickly, driving the torque to zero. However, a key trait of waves is their ability to transport angular momentum. Wave action can prevent saturation by transporting angular momentum away from the resonance zone to more distant parts of the disk; this results in a sustained torque that can significantly modify the perturber's orbit. This talk will review recent changes in the cosmogonic paradigm brought about by ongoing efforts to incorporate disk-planet interactions into models of planetary formation. One dramatic development has been the realization that massive, planet-sized bodies may exhibit a substantial degree of mobility in the presence of their precursor nebula. Not only does this relate to accretion timescales and the provenance of planetary material, but it also has important implications for the origin of close stellar companions and the ultimate survival of planetary systems. Wave action can also manifest itself in the planetesimal disk, even after the dissipation of the nebula. The long-term evolution of residual populations such as the Kuiper and asteroid belts may have been strongly influence by this mechanism. We will outline some of the outstanding problems that have yet to be explored concerning this important

  5. Idiopathic Pulmonary Fibrosis: Diagnosis and Clinical Manifestations

    PubMed Central

    Nakamura, Yutaro; Suda, Takafumi

    2015-01-01

    Idiopathic pulmonary fibrosis (IPF) is a parenchymal lung disease characterized by progressive interstitial fibrosis. The clinical course of IPF can be unpredictable and may be punctuated by acute exacerbations. Although much progress is being made in unraveling the mechanisms underlying IPF, effective therapy for improving survival remains elusive. Longitudinal disease profiling, especially in terms of clinical manifestations in a large cohort of patients, should lead to proper management of the patients and development of new treatments for IPF. Appropriate multidisciplinary assessment in ongoing registries is required to achieve this. This review summarizes the current status of the diagnosis and clinical manifestations of IPF.

  6. Lupus as a paraneoplastic manifestation of cholangiocarcinoma.

    PubMed

    González Amores, Yolanda; Hernando Rebollar, Sofía; Casado Bernabeu, Aida

    2016-05-01

    Tumors originating in the digestive system, like those in other areas, whether solid or otherwise, may present with extradigestive manifestations in the setting of a paraneoplastic syndrome. Systemic lupus erythematosus (SLE) is an autoimmune condition most commonly involving women of childbearing age. On occasion it represents a paraneoplastic manifestation heralding a primary tumor. Cancer suspicion is therefore a key element for newly diagnosed SLE cases with nonstandard epidemiology even in the absence of suggestive symptoms, and digestive tumors should be included in the differential diagnosis. PMID:26925842

  7. Ocular manifestations of feline viral diseases.

    PubMed

    Stiles, Jean

    2014-08-01

    Feline viral diseases are common and cats can be presented with a variety of clinical manifestations. Ocular disease associated with viral pathogens is not unusual, particularly with viruses causing upper respiratory tract disease in cats, such as feline herpesvirus type 1 and feline calicivirus. These agents mainly cause ocular surface disease. Other viruses, such as feline immunodeficiency virus and feline coronavirus, can cause uveitis, while feline leukemia virus can induce ocular lymphosarcoma. This review covers the most common viral pathogens of cats that cause ocular manifestations, the specific features of the ocular diseases caused by these viruses and therapeutic recommendations. PMID:24461645

  8. Secular Evolution in Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Kormendy, John

    2013-10-01

    Self-gravitating systems evolve toward the most tightly bound configuration that is reachable via the evolution processes that are available to them. They do this by spreading -- the inner parts shrink while the outer parts expand -- provided that some physical process efficiently transports energy or angular momentum outward. The reason is that self-gravitating systems have negative specific heats. As a result, the evolution of stars, star clusters, protostellar and protoplanetary disks, black hole accretion disks and galaxy disks are fundamentally similar. How evolution proceeds then depends on the evolution processes that are available to each kind of self-gravitating system. These processes and their consequences for galaxy disks are the subjects of my lectures and of this Canary Islands Winter School. I begin with a review of the formation, growth and death of bars. Then I review the slow (`secular') rearrangement of energy, angular momentum, and mass that results from interactions between stars or gas clouds and collective phenomena such as bars, oval disks, spiral structure and triaxial dark haloes. The `existence-proof' phase of this work is largely over: we have a good heuristic understanding of how nonaxisymmetric structures rearrange disk gas into outer rings, inner rings and stuff dumped onto the centre. The results of simulations correspond closely to the morphology of barred and oval galaxies. Gas that is transported to small radii reaches high densities. Observations confirm that many barred and oval galaxies have dense central concentrations of gas and star formation. The result is to grow, on timescales of a few Gyr, dense central components that are frequently mistaken for classical (elliptical-galaxy-like) bulges but that were grown slowly out of the disk (not made rapidly by major mergers). The resulting picture of secular galaxy evolution accounts for the richness observed in galaxy structure. We can distinguish between classical and pseudo

  9. Warm Disks from Giant Impacts

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2015-10-01

    In the process of searching for exoplanetary systems, weve discovered tens of debris disks close around distant stars that are especially bright in infrared wavelengths. New research suggests that we might be looking at the late stages of terrestrial planet formation in these systems.Forming Terrestrial PlanetsAccording to the widely-accepted formation model for our solar-system, protoplanets the size of Mars formed within a protoplanetary disk around our Sun. Eventually, the depletion of the gas in the disk led the orbits of these protoplanets to become chaotically unstable. Finally, in the giant impact stage, many of the protoplanets collided with each other ultimately leading to the formation of the terrestrial planets and their moons as we know them today.If giant impact stages occur in exoplanetary systems, too leading to the formation of terrestrial exoplanets how would we detect this process? According to a study led by Hidenori Genda of the Tokyo Institute of Technology, we might be already be witnessing this stage in observations of warm debris disks around other stars. To test this, Genda and collaborators model giant impact stages and determine what we would expect to see from a system undergoing this violent evolution.Modeling CollisionsSnapshots of a giant impact in one of the authors simulations. The collision causes roughly 0.05 Earth masses of protoplanetary material to be ejected from the system. Click for a closer look! [Genda et al. 2015]The collaborators run a series of simulations evolving protoplanetary bodies in a solar system. The simulations begin 10 Myr into the lifetime of the solar system, i.e., after the gas from the protoplanetary disk has had time to be cleared and the protoplanetary orbits begin to destabilize. The simulations end when the protoplanets are done smashing into each other and have again settled into stable orbits, typically after ~100 Myr.The authors find that, over an average giant impact stage, the total amount of

  10. Declustering databases on heterogeneous disk systems

    SciTech Connect

    Chen, Ling T.; Rotem, D.; Seshadri, S.

    1995-04-01

    Declustering is a well known strategy to achieve maximum I/O parallelism in multi-disk systems. Many declustering methods have been proposed for symmetrical disk systems, i.e., multi-disk systems in which all disks have the same speed and capacity. This work deals with the problem of adapting such declustering methods to work in heterogeneous environments. In such environments these are many types of disks and servers with a large range of speeds and capacities. We deal first with the case of perfectly declustered queries, i.e., queries which retrieve a fixed proportion of the answer from each disk. We show that the fraction of the dataset which must be allocated to each disk is affected by both the relative speed and capacity of the disk. Furthermore, the hierarchical structure of most distributed systems, where groups of disks are placed in servers, imposes further complications due to variations . in server and network bandwidths which may affect the actual achievable transfer rates. We propose an algorithm which determines the fraction of the dataset which must be loaded on each disk. The algorithm may be tailored to find disk loading for minimal response time for a given database size, or to compute a system profile showing the optimal loading of the disks for all possible ranges of database sizes. Next we look at the probabilistic aspects of this problem and show how to optimize the expected retrieval time when the Proportions of the data retrieved from each disk axe random variables. We show the rather surprising result that in this case to achieve optimality, the fraction of the data loaded on each disk must not simply be proportional to its speed but rather some compensation must be made with bias towards the faster disks. The methods proposed here are general and can be used in conjunction with most known symmetric declustering methods.

  11. Accretion disks in interacting binary stars

    NASA Technical Reports Server (NTRS)

    Lin, D. N. C.

    1991-01-01

    Accretion disks have most often been analyzed in cataclysmic variables (CVs); the structure and evolution of accretion disks is defined by angular momentum transfer processes. Detailed atmospheric models indicate that angular momentum transport is efficient, that CV outbursts are regulated by mass transfer variations in the disk, and that they may be initiated either from the inner and outer regions of the disk. Tidal effects on the companion are noted to be capable of inducing a significant departure from Keplerian flow near the outer region of the disk.

  12. Vibration Based Crack Detection in a Rotating Disk. Part 2; Experimental Results

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Haase, Wayne C.; Baaklini, George

    2005-01-01

    This paper describes the experimental results concerning the detection of a crack in a rotating disk. The goal was to utilize blade tip clearance and shaft vibration measurements to monitor changes in the system's center of mass and/or blade deformation behaviors. The concept of the approach is based on the fact that the development of a disk crack results in a distorted strain field within the component. As a result, a minute deformation in the disk's geometry as well as a change in the system's center of mass occurs. Here, a notch was used to simulate an actual crack. The vibration based experimental results failed to identify the existence of a notch when utilizing the approach described above, even with a rather large, circumferential notch (l.2 in.) located approximately mid-span on the disk (disk radius = 4.63 in. with notch at r = 2.12 in.). This was somewhat expected, since the finite element based results in Part 1 of this study predicted changes in blade tip clearance as well as center of mass shifts due to a notch to be less than 0.001 in. Therefore, the small changes incurred by the notch could not be differentiated from the mechanical and electrical noise of the rotor system. Although the crack detection technique of interest failed to identify the existence ofthe notch, the vibration data produced and captured here will be utilized in upcoming studies that will focus on different data mining techniques concerning damage detection in a disk.

  13. Escape conditions of radiative-driven strati from luminous accretion disks

    NASA Astrophysics Data System (ADS)

    Nakai, Takuya; Fukue, Jun

    2015-10-01

    We examine the dynamical motion and escape conditions of continuum-driven strati (flat cloud) with finite optical depth from luminous accretion disks around a black hole. We adopt the near-disk approximation, and treat the problem in the framework of special relativity, where the radiation drag force as well as the radiation pressure are included. We find that the optically thin strati are easy to accelerate, compared with the particles, and the escape condition of the stratus is reduced. That is, when the disk luminosity is around the Eddington luminosity, the optically thin strati can escape from the inner disk (≲ 20 rg; rg being the Schwarzschild radius). When the disk luminosity is about half the Eddington luminosity, it can escape at around 5 rg. This is due to the translucent effect. In addition, the trajectories of the strati are not vertical, but a funnel-like shape due to the centrifugal force. Stratus outflow could easily blow out from usual accretion disks with sub-Eddington luminosities, and this may explain outflows observed in broad absorption line quasars and ultra-fast outflow objects.

  14. On the peculiarities of manifestation of kG magnetic elements in observations of the Sun with low spatial resolution

    NASA Astrophysics Data System (ADS)

    Demidov, Mikhail L.; Veretsky, Renat M.; Kiselev, Alexander V.

    2015-10-01

    On the agenda of modern astrophysics is the exploration of not only disk-integrated stellar magnetic fields but surface mapping of them. However, it is hardly possible to expect that spatial resolution better than some dozens or hundreds pixels over stellar disk will be achieved for this goal in the foreseeable future. Among other reasons this fact makes very important observations of the average and large-scale magnetic fields of the Sun, which can be naturally used for testing polarimetric measurements on other stars, especially on solar-type stars. In this study we explore different aspects of observations of solar magnetic fields (SMF) with low spatial resolution, including Sun-as-a-star observations, which are characterized by extremely low magnetic flux densities. Comparison of disk-integrated and spatially resolved Stokes observations of the Sun allow us to demonstrate how Stokes V profiles depend on the distribution of large-scale magnetic fields in the disk center. It is shown that center-to-limb variations of magnetic strength ratios (MSR) and area asymetries, most likely could be interpreted as the manifestation of kG magnetic flux tubes. We have made cross-calibration of the full-disk magnetograms obtained by space-borned SDO/HMI and by the ground-based STOP telescope, and pretty good agreement is found. Finally, the absence of significant systematic time variations of MSRs with solar cycle is demonstrated.

  15. Warped circumbinary disks in active galactic nuclei

    SciTech Connect

    Hayasaki, Kimitake; Sohn, Bong Won; Jung, Taehyun; Zhao, Guangyao; Okazaki, Atsuo T.; Naito, Tsuguya

    2014-07-20

    We study a warping instability of a geometrically thin, non-self-gravitating disk surrounding binary supermassive black holes on a circular orbit. Such a circumbinary disk is subject to not only tidal torques due to the binary gravitational potential but also radiative torques due to radiation emitted from an accretion disk around each black hole. We find that a circumbinary disk initially aligned with the binary orbital plane is unstable to radiation-driven warping beyond the marginally stable warping radius, which is sensitive to both the ratio of vertical to horizontal shear viscosities and the mass-to-energy conversion efficiency. As expected, the tidal torques give no contribution to the growth of warping modes but tend to align the circumbinary disk with the orbital plane. Since the tidal torques can suppress the warping modes in the inner part of circumbinary disk, the circumbinary disk starts to be warped at radii larger than the marginally stable warping radius. If the warping radius is of the order of 0.1 pc, a resultant semi-major axis is estimated to be of the order of 10{sup –2} pc to 10{sup –4} pc for 10{sup 7} M{sub ☉} black hole. We also discuss the possibility that the central objects of observed warped maser disks in active galactic nuclei are binary supermassive black holes with a triple disk: two accretion disks around the individual black holes and one circumbinary disk surrounding them.

  16. Warped Circumbinary Disks in Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Hayasaki, Kimitake; Sohn, Bong Won; Okazaki, Atsuo T.; Jung, Taehyun; Zhao, Guangyao; Naito, Tsuguya

    2014-07-01

    We study a warping instability of a geometrically thin, non-self-gravitating disk surrounding binary supermassive black holes on a circular orbit. Such a circumbinary disk is subject to not only tidal torques due to the binary gravitational potential but also radiative torques due to radiation emitted from an accretion disk around each black hole. We find that a circumbinary disk initially aligned with the binary orbital plane is unstable to radiation-driven warping beyond the marginally stable warping radius, which is sensitive to both the ratio of vertical to horizontal shear viscosities and the mass-to-energy conversion efficiency. As expected, the tidal torques give no contribution to the growth of warping modes but tend to align the circumbinary disk with the orbital plane. Since the tidal torques can suppress the warping modes in the inner part of circumbinary disk, the circumbinary disk starts to be warped at radii larger than the marginally stable warping radius. If the warping radius is of the order of 0.1 pc, a resultant semi-major axis is estimated to be of the order of 10-2 pc to 10-4 pc for 107 M ⊙ black hole. We also discuss the possibility that the central objects of observed warped maser disks in active galactic nuclei are binary supermassive black holes with a triple disk: two accretion disks around the individual black holes and one circumbinary disk surrounding them.

  17. Real-Life Contextual Manifestations of Wisdom

    ERIC Educational Resources Information Center

    Yang, Shih-Ying

    2008-01-01

    Wisdom pertains to managing human affairs, and it arises in highly contextualized situations. The present study aims to investigate manifestations of wisdom in real-life contexts through semi-structured interviews with 66 individuals nominated as wise persons. All nominees were ethnic Chinese from Taiwan, an East Asian country which has…

  18. Antisynthetase syndrome: two cases presenting orofacial manifestations.

    PubMed

    Gormley, M; Scully, C

    2014-03-01

    Antisynthetase syndrome is a rare autoimmune disease that is characterised by inflammatory myositis, and interstitial lung disease or chronic arthropathy, or both. To the best of our knowledge, orofacial manifestations have not previously been reported. We present 2 patients with orofacial disease: one with aphthous-like oral ulceration and the other with hyposalivation. PMID:24377442

  19. 19 CFR 123.32 - Manifests.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Manifests. 123.32 Section 123.32 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY CUSTOMS RELATIONS WITH CANADA AND MEXICO Shipments in Transit Through the United States § 123.32...

  20. Neoliberalism, Curriculum Development and Manifestations of "Creativity"

    ERIC Educational Resources Information Center

    Hakala, Juha T.; Uusikylä, Kari; Järvinen, Esa-Matti

    2015-01-01

    There is a manifest tendency for national education policy to follow global economic trends. In many Western industrialized countries, this relationship has intensified or strengthened within the last decades. The strengthening of this relationship has been seen, among other things, as evidence of the growing power of neoliberal ideology. The…

  1. 19 CFR 122.75 - Complete manifest.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Complete manifest. 122.75 Section 122.75 Customs Duties U.S. CUSTOMS AND BORDER PROTECTION, DEPARTMENT OF HOMELAND SECURITY; DEPARTMENT OF THE TREASURY AIR COMMERCE REGULATIONS Documents Required for Clearance and Permission To Depart;...

  2. Cardiovascular and renal manifestations of hyperthyroidism.

    PubMed

    Syme, Harriet M

    2007-07-01

    In the simplest terms, hyperthyroidism is the clinical syndrome that results from an excess of thyroid hormones. This review considers the effects of hyperthyroidism on the cardiovascular and renal systems by reviewing the available literature on the clinical manifestations of this syndrome in the cat and also considering experimental studies and experience in other species, including human beings. PMID:17619008

  3. Behavioral Manifestations of Child Sexual Abuse.

    ERIC Educational Resources Information Center

    Friedrich, William N.

    1998-01-01

    This paper on the behavioral manifestations of child sexual abuse first reviews previous research concerning child variables, parent/family variables, sexual abuse in combination with other maltreatment, and physiological outcomes. Criteria for future research are offered and specific research needs in the areas of developmental progression,…

  4. Dyslexia in Regular Orthographies: Manifestation and Causation

    ERIC Educational Resources Information Center

    Wimmer, Heinz; Schurz, Matthias

    2010-01-01

    This article summarizes our research on the manifestation of dyslexia in German and on cognitive deficits, which may account for the severe reading speed deficit and the poor orthographic spelling performance that characterize dyslexia in regular orthographies. An only limited causal role of phonological deficits (phonological awareness,…

  5. Retinal pigment epithelial hamartoma--unusual manifestations.

    PubMed Central

    Rosenberg, P. R.; Walsh, J. B.

    1984-01-01

    Hamartoma of the retinal pigment epithelium is an uncommon tumour of young adults. We have seen 2 patients with this clinical diagnosis, both with unusual manifestations. In one patient growth of the tumour was observed over a 5-year period. In the second patient arterial-arterial anastomoses were detected at a site distal to the tumour. Images PMID:6722077

  6. 40 CFR 267.72 - Manifest discrepancies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 267.72 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES (CONTINUED... differences between the quantity or type of hazardous waste designated on the manifest or shipping paper, and the quantity or type of hazardous waste a facility actually receives. Significant discrepancies...

  7. Accretion disks in Algols: Progenitors and evolution

    NASA Astrophysics Data System (ADS)

    Van Rensbergen, W.; De Greve, J. P.

    2016-08-01

    Context. There are only a few Algols with measured accretion disk parameters. These measurements provide additional constraints for tracing the origin of individual systems, narrowing down the initial parameter space. Aims: We investigate the origin and evolution of six Algol systems with accretion disks to find the initial parameters and evolutionary constraints for them. Methods: With a modified binary evolution code, series of close binary evolution are calculated to obtain the best match for observed individual systems. Results: Initial parameters for six Algol systems with accretion disks were determined matching both the present system parameters and the observed disk characteristics. Conclusions: When Roche lobe overflow (RLOF) starts during core hydrogen burning of the donor, the disk lifetime was found to be short. The disk luminosity is comparable to the luminosity of the gainer during a large fraction of the disk lifetime.

  8. A Comprehensive Study of Proto-Planetary Disks around Herbig Ae/Be stars using Long-Baseline Infrared Interferometry.

    NASA Astrophysics Data System (ADS)

    Tannirkulam, Ajay

    2007-12-01

    Planetary systems are born in circumstellar disks around young stellar objects (YSOs) and the disk is thought to play a major role in the evolution of planetary systems. A good understanding of disk structure and its time evolution is therefore essential in comprehending planet formation, planet migration and the diversity of planetary systems. In this thesis, I use high angular resolution observations and state-of-the-art radiative transfer modeling to probe circumstellar disk structure and validate current disk models. First, I discuss models and observations of the gas-dust transition region in YSOs. The dust component in circumstellar disks gets truncated at a finite radius from the central star, inside of which it is too hot for dust to survive. The truncated disk forms an "evaporation front" whose shape depends sensitively on dust properties. The possibility of using the front as a probe of the dust physics operating in circumstellar disks is explored. The CHARA near-infrared (near-IR) array is used to resolve out the evaporation front in the Herbig Ae stars MWC275 and AB Aur, and the presence of an additional near-IR opacity source within the "conventional" dust destruction radius is reported. Second, I describe comprehensive disk models that simultaneously explain the SED (from UV to milli-meter ) and long-baseline interferometry (from near-IR to mm) of Herbig Ae stars. The models are constrained with a wide range of data drawn from the literature as well as new observations made for this study. Specifically, new H and K band interferometry from the CHARA array and new mid-IR interferometry from the novel Keck Aperture Masking Experiment is reported. I will end my talk with a discussion on exciting prospects for measuring the gas-disk morphology on scales of fractions of an AU with the CHARA array, introducing a new powerful tool to understand the "star-disk connection".

  9. Herschel evidence for disk flattening or gas depletion in transitional disks

    SciTech Connect

    Keane, J. T.; Pascucci, I.; Espaillat, C.; Woitke, P.; Andrews, S.; Kamp, I.; Thi, W.-F.; Meeus, G.; Dent, W. R. F.

    2014-06-01

    Transitional disks are protoplanetary disks characterized by reduced near- and mid-infrared emission, with respect to full disks. This characteristic spectral energy distribution indicates the presence of an optically thin inner cavity within the dust disk believed to mark the disappearance of the primordial massive disk. We present new Herschel Space Observatory PACS spectra of [O I] 63.18 μm for 21 transitional disks. Our survey complements the larger Herschel GASPS program ({sup G}as in Protoplanetary Systems{sup )} by quadrupling the number of transitional disks observed with PACS in this wavelength. [O I] 63.18 μm traces material in the outer regions of the disk, beyond the inner cavity of most transitional disks. We find that transitional disks have [O I] 63.18 μm line luminosities ∼2 times fainter than their full disk counterparts. We self-consistently determine various stellar properties (e.g., bolometric luminosity, FUV excess, etc.) and disk properties (e.g., disk dust mass, etc.) that could influence the [O I] 63.18 μm line luminosity, and we find no correlations that can explain the lower [O I] 63.18 μm line luminosities in transitional disks. Using a grid of thermo-chemical protoplanetary disk models, we conclude that either transitional disks are less flared than full disks or they possess lower gas-to-dust ratios due to a depletion of gas mass. This result suggests that transitional disks are more evolved than their full disk counterparts, possibly even at large radii.

  10. Warm Debris Disks from WISE

    NASA Technical Reports Server (NTRS)

    Padgett, Deborah L.

    2011-01-01

    "The Wide Field Infrared Survey Explorer (WISE) has just completed a sensitive all-sky survey in photometric bands at 3.4, 4.6, 12, and 22 microns. We report on a preliminary investigation of main sequence Hipparcos and Tycho catalog stars with 22 micron emission in excess of photospheric levels. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets and is preferentially found in young systems with ages < 1 Gyr. Nearly a hundred new warm debris disk candidates are detected among FGK stars and a similar number of A stars within 120 pc. We are in the process of obtaining spectra to determine spectral types and activity level of these stars and are using HST, Herschel and Keck to characterize the dust, multiplicity, and substellar companions of these systems. In this contribution, we will discuss source selection methods and individual examples from among the WISE debris disk candidates. "

  11. Advanced optical disk storage technology

    NASA Technical Reports Server (NTRS)

    Haritatos, Fred N.

    1996-01-01

    There is a growing need within the Air Force for more and better data storage solutions. Rome Laboratory, the Air Force's Center of Excellence for C3I technology, has sponsored the development of a number of operational prototypes to deal with this growing problem. This paper will briefly summarize the various prototype developments with examples of full mil-spec and best commercial practice. These prototypes have successfully operated under severe space, airborne and tactical field environments. From a technical perspective these prototypes have included rewritable optical media ranging from a 5.25-inch diameter format up to the 14-inch diameter disk format. Implementations include an airborne sensor recorder, a deployable optical jukebox and a parallel array of optical disk drives. They include stand-alone peripheral devices to centralized, hierarchical storage management systems for distributed data processing applications.

  12. Solar disk sextant optical configuration

    NASA Technical Reports Server (NTRS)

    Chiu, H.-Y.; Maier, E.; Schatten, K. H.; Sofia, S.

    1984-01-01

    In this paper the performance of a plausible configuration for the solar disk sextant, an instrument to be used to monitor the solar diameter, is evaluated. Overall system requirements are evaluated, and tolerable uncertainties are obtained. It is concluded that by using a beam splitting wedge, a folded optics design can be used to measure the solar diameter to an accuracy of 10 to the -6th, despite the greater aberrations present in such optical systems.

  13. Competition for finite resources

    NASA Astrophysics Data System (ADS)

    Cook, L. Jonathan; Zia, R. K. P.

    2012-05-01

    The resources in a cell are finite, which implies that the various components of the cell must compete for resources. One such resource is the ribosomes used during translation to create proteins. Motivated by this example, we explore this competition by connecting two totally asymmetric simple exclusion processes (TASEPs) to a finite pool of particles. Expanding on our previous work, we focus on the effects on the density and current of having different entry and exit rates.

  14. Accretion outbursts in self-gravitating protoplanetary disks

    SciTech Connect

    Bae, Jaehan; Hartmann, Lee; Zhu, Zhaohuan; Nelson, Richard P. E-mail: lhartm@umich.edu E-mail: r.p.nelson@qmul.ac.uk

    2014-11-01

    We improve on our previous treatments of the long-term evolution of protostellar disks by explicitly solving disk self-gravity in two dimensions. The current model is an extension of the one-dimensional layered accretion disk model of Bae et al. We find that gravitational instability (GI)-induced spiral density waves heat disks via compressional heating (i.e., PdV work), and can trigger accretion outbursts by activating the magnetorotational instability (MRI) in the magnetically inert disk dead zone. The GI-induced spiral waves propagate well inside of the gravitationally unstable region before they trigger outbursts at R ≲ 1 AU where GI cannot be sustained. This long-range propagation of waves cannot be reproduced with the previously used local α treatments for GI. In our standard model where zero dead-zone residual viscosity (α{sub rd}) is assumed, the GI-induced stress measured at the onset of outbursts is locally as large as 0.01 in terms of the generic α parameter. However, as suggested in our previous one-dimensional calculations, we confirm that the presence of a small but finite α{sub rd} triggers thermally driven bursts of accretion instead of the GI + MRI-driven outbursts that are observed when α{sub rd} = 0. The inclusion of non-zero residual viscosity in the dead zone decreases the importance of GI soon after mass feeding from the envelope cloud ceases. During the infall phase while the central protostar is still embedded, our models stay in a 'quiescent' accretion phase with M-dot {sub acc}∼10{sup −8}--10{sup −7} M{sub ⊙} yr{sup −1} over 60% of the time and spend less than 15% of the infall phase in accretion outbursts. While our models indicate that episodic mass accretion during protostellar evolution can qualitatively help explain the low accretion luminosities seen in most low-mass protostars, detailed tests of the mechanism will require model calculations for a range of protostellar masses with some constraint on the initial core

  15. 19 CFR 123.22 - In-transit manifest.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false In-transit manifest. 123.22 Section 123.22 Customs... CBP RELATIONS WITH CANADA AND MEXICO Shipments in Transit Through Canada or Mexico § 123.22 In-transit manifest. (a) Manifest required. A manifest in duplicate covering the in-transit merchandise which is...

  16. 40 CFR 262.54 - Special manifest requirements.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE Exports of Hazardous Waste § 262.54 Special manifest requirements. A primary exporter must comply with the manifest requirements of 40 CFR 262.20... (as defined in 40 CFR 264.72(a)) between the manifest and the shipment. A copy of the manifest...

  17. 40 CFR 262.54 - Special manifest requirements.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE Exports of Hazardous Waste § 262.54 Special manifest requirements. A primary exporter must comply with the manifest requirements of 40 CFR 262.20... (as defined in 40 CFR 264.72(a)) between the manifest and the shipment. A copy of the manifest...

  18. 40 CFR 262.54 - Special manifest requirements.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE Exports of Hazardous Waste § 262.54 Special manifest requirements. A primary exporter must comply with the manifest requirements of 40 CFR 262.20... (as defined in 40 CFR 264.72(a)) between the manifest and the shipment. A copy of the manifest...

  19. 40 CFR 262.54 - Special manifest requirements.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE Exports of Hazardous Waste § 262.54 Special manifest requirements. A primary exporter must comply with the manifest requirements of 40 CFR 262.20... (as defined in 40 CFR 264.72(a)) between the manifest and the shipment. A copy of the manifest...

  20. 40 CFR 262.54 - Special manifest requirements.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE Exports of Hazardous Waste § 262.54 Special manifest requirements. A primary exporter must comply with the manifest requirements of 40 CFR 262.20... (as defined in 40 CFR 264.72(a)) between the manifest and the shipment. A copy of the manifest...

  1. A Pulsar and a Disk

    NASA Astrophysics Data System (ADS)

    Kohler, Susanna

    2016-07-01

    Recent, unusual X-ray observations from our galactic neighbor, the Small Magellanic Cloud, have led to an interesting model for SXP 214, a pulsar in a binary star system.Artists illustration of the magnetic field lines of a pulsar, a highly magnetized, rotating neutron star. [NASA]An Intriguing BinaryAn X-ray pulsar is a magnetized, rotating neutron star in a binary system with a stellar companion. Material is fed from the companion onto the neutron star, channeled by the objects magnetic fields onto a hotspot thats millions of degrees. This hotspot rotating past our line of sight is what produces the pulsations that we observe from X-ray pulsars.Located in the Small Magellanic Cloud, SXP 214 is a transient X-ray pulsar in a binary with a Be-type star. This star is spinning so quickly that material is thrown off of it to form a circumstellar disk.Recently, a team of authors led by JaeSub Hong (Harvard-Smithsonian Center for Astrophysics) have presented new Chandra X-ray observations of SXP 214, tracking it for 50 ks (~14 hours) in January 2013. These observations reveal some very unexpected behavior for this pulsar.X-ray PuzzleThe energy distribution of the X-ray emission from SXP 214 over time. Dark shades or blue colors indicate high counts, and light shades or yellow colors indicate low counts. Lower-energy X-ray emission appeared only later, after about 20 ks. [Hong et al. 2016]Three interesting pieces of information came from the Chandra observations:SXP 214s rotation period was measured to be 211.5 s an increase in the spin rate since the discovery measurement of a 214-second period. Pulsars usually spin down as they lose angular momentum over time so what caused this one to spin up?Its overall X-ray luminosity steadily increased over the 50 ks of observations.Its spectrum became gradually softer (lower energy) over time; in the first 20 ks, the spectrum only consisted of hard X-ray photons above 3 keV, but after 20 ks, softer X-ray photons below 2 ke

  2. Disk Galaxy Stellar Velocity Ellipsoids

    NASA Astrophysics Data System (ADS)

    Westfall, Kyle B.; Bershady, M. A.; Verheijen, M. A. W.; Andersen, D. R.; Swaters, R. A.

    2007-12-01

    We have measured the disk stellar velocity ellipsoids in a subset of spiral galaxies observed for the Disk-Mass Survey, which provide information on disk stability and secular heating mechanisms. Our methodology invokes our 2D ionized gas and stellar kinematics and a suite of dynamical assumptions based on the Jeans' equations. When combined with orthogonal axes from our 2D data, either the epicycle approximation (EA) or asymmetric drift (AD) equation may close the necessary equation set, individually. We have isolated large observational and inherent systematic effects via EA-only, AD-only, and EA+AD ellipsoid decomposition methodologies. In an attempt to minimize these effects and generate robust ellipsoid measurements we explore constraints provided by higher order expansions of the Jeans' equations and direct orbital integrations. We compare our best ellipsoid axial ratio estimates to similar measurements made by, e.g., van der Kruit & de Grijs (1999, A&A, 352, 129) and Shapiro et al. (2003, AJ, 126, 2707). Finally, we discuss possibilities for the measurement of vertical velocity dispersions in low-surface-brightness galaxies by applying the characterization of the stellar velocity ellipsoid in late-type galaxies. This work is supported by the National Science Foundation (AST-0607516).

  3. Digital droplet PCR on disk.

    PubMed

    Schuler, Friedrich; Trotter, Martin; Geltman, Marcel; Schwemmer, Frank; Wadle, Simon; Domínguez-Garrido, Elena; López, María; Cervera-Acedo, Cristina; Santibáñez, Paula; von Stetten, Felix; Zengerle, Roland; Paust, Nils

    2016-01-01

    Existing systems for digital droplet PCR (ddPCR) either suffer from low integration or are difficult to introduce to mass fabrication. Here we present an integrated system that is compatible to mass fabrication and combines emulsification, PCR, and fluorescence readout in a single chamber within a disposable cartridge (disk). Droplets are generated by injecting the sample into fluorinated oil via centrifugal step emulsification. The resulting emulsion is aligned in the PCR and readout zone by capillary action. During thermocycling, gas bubbles generated by degassing are removed by capillary driven transport through tapered regions in the PCR chamber. Thereby, the positioning of the emulsion within the readout zone of the PCR chamber is ensured at any time and no bubbles are present during readout. Manual handling of the disk solely requires pipetting of oil and PCR mix into the inlet structures, placing the disk into the thermocycler and subsequently into a microarray scanner. The functionality of the ddPCR process chain is demonstrated by quantitative detection of the cystic fibrosis causing mutation p.Phe508del, which is of interest for non-invasive prenatal testing (NIPT). The mutation was detected in a concentration range spanning four orders of magnitude. We envision that this work will lay the base for the development of highly integrated sample-to-digital-answer PCR systems that can be employed in routine clinical diagnosis. PMID:26610263

  4. Planetesimal clustering in protoplanetary disks

    NASA Astrophysics Data System (ADS)

    Tanga, P.; Michel, P.; Richardson, D. C.

    2001-11-01

    The usual approach to the study of planetary accretion always considers homogeneous distributions of planetesimals and isotropic velocity dispersions. Nevertheless, if small planetesimals (in the 1 cm - 1 m range) were affected by the turbulent gas disk motion, several studies have suggested that the properties of homogeneity could be easily lost (see e.g. Tanga et al. 1996, Bracco et al. 1999, Godon and Livio 2000). In fact, due to gas drag, surface density fluctuations can appear, as well as a correlation in planetesimal velocities. In particular, the presence of vortices seems to be very effective in this sense. Unfortunately, if a dust surface density close to that of a "Minimum Mass" Solar Nebula is assumed, the numerical integration of self-gravitating planetesimal systems in the concerned size range is not possible due to the huge number of particles involved. Therefore, our first step has been the investigation of the role of pure self-gravitation in the evolution of planetesimal clusters in disks of 104 - 106 bodies (implying thus much larger bodies) by use of the gravitational N-body code pkdgrav. Preliminary results clearly show that under certain conditions a local planetesimal clustering can remain compact over several disk revolutions, provided that a velocity correlation among neighbouring particles is present. An appropriate rescaling of these results toward planetesimals of smaller sizes shows that cluster survival is relevant in affecting their dynamics, collisional properties and growth rate. These processes could then be very relevant in the early stages of planetary system formation.

  5. The Earliest Stage of Planet Formation: Disk-Planet Interactions in Protoplanetary Disks and Observations of Transitional Disks

    NASA Astrophysics Data System (ADS)

    Dong, Ruobing; Rafikov, R.; Stone, J. M.; Hartmann, L. W.; SEEDS Team

    2013-01-01

    I will first talk about numerical simulations of disk-planet interactions in protoplanetary disks. Particularly, I’ll discuss the damping of the density waves excited by planets due to the nonlinearity in their propagation, which can result in gap opening in a low viscosity disk by low mass planets. I'll also discuss the effects of various numerical algorithms and parameters in simulations of disk-planet interaction, and address the question of how to produce correct simulations. Then I’ll move on to recent Subaru observations of transitional disks, which are protoplanetary disks with central depleted regions (cavities). Several ideas on the formation of transitional disks have been proposed, including gaps opened by planet(s). Recently, Subaru directly imaged a number of such disks at near infrared (NIR) wavelengths (the SEEDS project) with high spatial resolution and small inner working angles. Using radiative transfer simulations, we study the structure of transitional disks by modeling the NIR images, the SED, and the sub-mm observations from literature (whenever available) simultaneously. We obtain physical disk+cavity structures, and constrain the spatial distribution of the dust grains, particularly inside the cavity and at the cavity edge. Interestingly, we find that in some cases cavities are not present in the scattered light. In such cases we present a new transitional disk model to simultaneously account for all observations. Decoupling between the sub-um-sized and mm-sized grains inside the cavity is required, which may necessitate the dust filtration mechanism. For another group of transitional disks in which Subaru does reveal the cavities at NIR, we focus on whether grains at different sizes have the same spatial distribution or not. We use our modeling results to constrain transitional disk formation theories, particularly to comment on their possible planets origin.

  6. Decoding the Inner Disk about - Pictoris

    NASA Astrophysics Data System (ADS)

    Schultz, Alfred

    1996-07-01

    The FOS will be used to study the UV emission linecharacteristics of the inner disk about Beta Pictoris at adistance of 1.3" from the star. Our goal is to investigatethe proposed infall and subsequent sublimation of comet-likebodies into beta Pictoris and to study the composition ofinner disk material. Due to the favorable edge-on orientationof the disk, the gaseous component of the disk has beendetected in absorption. The inner disk gases are excited, dissociated, and ionized by stellar photons. The detection ofemissions from the gaseous disk in the vicinity of the star,possibly cometary in nature (eg., CS 2576 Angstrom, OH 3064Angstrom), would unequivocally establish the sublimation ofcomet-like bodies or possibly volatiles from grains within thecircumstellar disk. Our ultimate goal is to ascertain thecomposition of the inner disk.The GHRS will be employed to acquire the bright targets(alpha and beta Pictoris) followed by slewing the telescope toposition the targets into the FOS aperture. The core of the PSFwill be positioned behind the space separating the FOS 0.5-PAIRapertures. Spectra using the G190H and G270H gratings, spectralinterval 1573 - 3301 Angstrom, will be obtained of both sidesof the disk. Cycle 6 is the last opportunity to assess the spectralcharacteristics of the inner disk material in this wavelength region.

  7. High power disk lasers: advances and applications

    NASA Astrophysics Data System (ADS)

    Havrilla, David; Holzer, Marco

    2011-02-01

    Though the genesis of the disk laser concept dates to the early 90's, the disk laser continues to demonstrate the flexibility and the certain future of a breakthrough technology. On-going increases in power per disk, and improvements in beam quality and efficiency continue to validate the genius of the disk laser concept. As of today, the disk principle has not reached any fundamental limits regarding output power per disk or beam quality, and offers numerous advantages over other high power resonator concepts, especially over monolithic architectures. With well over 1000 high power disk lasers installations, the disk laser has proven to be a robust and reliable industrial tool. With advancements in running cost, investment cost and footprint, manufacturers continue to implement disk laser technology with more vigor than ever. This paper will explain important details of the TruDisk laser series and process relevant features of the system, like pump diode arrangement, resonator design and integrated beam guidance. In addition, advances in applications in the thick sheet area and very cost efficient high productivity applications like remote welding, remote cutting and cutting of thin sheets will be discussed.

  8. Elastic Torque on a Ferromagnetic Disk within a Nematic Liquid Crystal

    NASA Astrophysics Data System (ADS)

    Rovner, Joel B.; Borgnia, Dan S.; Lapointe, Clayton P.; Reich, Daniel H.; Leheny, Robert L.

    2012-02-01

    An aspherical particle suspended in a nematic liquid crystal will impose an orientationally dependent energy due to coupling to the nematic elasticity. This energy depends strongly on the anchoring conditions on the surface of the inclusion, its shape, as well as the proximity of other boundary conditions on the fluid such as those set by the container. To study these properties, ferromagnetic nickel disks with homeotropic surface anchoring were suspended in the liquid crystal 4-cyano-4'-pentylbiphenyl (5CB) in a planar cell. The disks, 300 nm in thickness and 10 μm in diameter, possess a permanent magnetic moment confined to the disk's plane. In the absence of any external torque the disks align with the normal to their faces parallel to the director. Rotating of the disks from this preferred orientation creates an elastic deformation that is manifested by an opposing torque. Balancing this torque with the torque from an external magnetic field for various angles of rotation, we have mapped out the orientationally dependent energy. Over a large range of angles the torque shows a linear dependence as predicted by an electrostatic analogy.

  9. DUSTY DISKS AROUND WHITE DWARFS. I. ORIGIN OF DEBRIS DISKS

    SciTech Connect

    Dong Ruobing; Wang Yan; Lin, D. N. C.; Liu, X.-W. E-mail: yuw123@psu.ed E-mail: liuxw@bac.pku.edu.c

    2010-06-01

    A significant fraction of the mature FGK stars have cool dusty disks at least an order of magnitude brighter than the solar system's outer zodiacal light. Since such dusts must be continually replenished, they are generally assumed to be the collisional fragments of residual planetesimals analogous to the Kuiper-Belt objects. At least 10% of solar-type stars also bear gas giant planets. The fraction of stars with known gas giants or detectable debris disks (or both) appears to increase with the stellar mass. Here, we examine the dynamical evolution of systems of long-period gas giant planets and residual planetesimals as their host stars evolve off the main sequence, lose mass, and form planetary nebula around remnant white dwarf cores. The orbits of distant gas giant planets and super-km-size planetesimals expand adiabatically. During the most intense asymptotic giant branch mass-loss phase, sub-meter-size particles migrate toward their host stars due to the strong hydrodynamical drag by the intense stellar wind. Along their migration paths, gas giant planets capture and sweep up sub-km-size planetesimals onto their mean-motion resonances. These planetesimals also acquire modest eccentricities which are determined by the mass of the perturbing planets, and the rate and speed of stellar mass loss. The swept-up planetesimals undergo disruptive collisions which lead to the production of grains with an extended size range. The radiation drag on these particles is ineffective against the planets' resonant barrier and they form 30-50 AU size rings which can effectively reprocess the stellar irradiation in the form of FIR continuum. We identify the recently discovered dust ring around the white dwarf WD 2226-210 at the center of the Helix nebula as a prototype of such disks and suggest such rings may be common.

  10. Continuum percolation on nonorientable surfaces: the problem of permeable disks on a Klein bottle

    NASA Astrophysics Data System (ADS)

    Borman, V. D.; Grekhov, A. M.; Tronin, V. N.; Tronin, I. V.

    2015-11-01

    The percolation threshold and wrapping probability (R ∞) for the two-dimensional problem of continuum percolation on the surface of a Klein bottle have been calculated by the Monte Carlo method with the Newman-Ziff algorithm for completely permeable disks. It has been shown that the percolation threshold of disks on the Klein bottle coincides with the percolation threshold of disks on the surface of a torus, indicating that this threshold is topologically invariant. The scaling exponents determining corrections to the wrapping probability and critical concentration owing to the finite-size effects are also topologically invariant. At the same time, the quantities R ∞ are different for percolation on the torus and Klein bottle and are apparently determined by the topology of the surface. Furthermore, the difference between the R ∞ values for the torus and Klein bottle means that at least one of the percolation clusters is degenerate.

  11. Mixed-Modal Disk Gas Squeeze Film Theoretical and Experimental Analysis

    NASA Astrophysics Data System (ADS)

    Wang, Yanzhong; Wei, Bin

    2013-09-01

    In order to investigate the gas squeeze film characteristics with mixed-modal disk excitation, an actuator with piezo-electric components is designed. Experiments show that different modal shapes of the disk are excited along with the changes of the actuator excitation frequency. The amplitude of the modal shape can reach the same order of magnitude as the squeeze film thickness, so the modal effects on the squeeze film characteristics cannot be ignored. In this paper, the simulating and fitting of the exciting disk modal shapes were finished by ANSYS and MATLAB. The actual film thickness equation was amended by the modal shape fitting curve. The gas film characteristic can be obtained by solving the Reynolds equation which is coupled with film thickness and motion equation. In this study, finite element simulation and differential numerical calculation results provided a good guidance to the piezoelectric actuator design.

  12. Refinement of elastic, poroelastic, and osmotic tissue properties of intervertebral disks to analyze behavior in compression.

    PubMed

    Stokes, Ian A F; Laible, Jeffrey P; Gardner-Morse, Mack G; Costi, John J; Iatridis, James C

    2011-01-01

    Intervertebral disks support compressive forces because of their elastic stiffness as well as the fluid pressures resulting from poroelasticity and the osmotic (swelling) effects. Analytical methods can quantify the relative contributions, but only if correct material properties are used. To identify appropriate tissue properties, an experimental study and finite element analytical simulation of poroelastic and osmotic behavior of intervertebral disks were combined to refine published values of disk and endplate properties to optimize model fit to experimental data. Experimentally, nine human intervertebral disks with adjacent hemi-vertebrae were immersed sequentially in saline baths having concentrations of 0.015, 0.15, and 1.5 M and the loss of compressive force at constant height (force relaxation) was recorded over several hours after equilibration to a 300-N compressive force. Amplitude and time constant terms in exponential force-time curve-fits for experimental and finite element analytical simulations were compared. These experiments and finite element analyses provided data dependent on poroelastic and osmotic properties of the disk tissues. The sensitivities of the model to alterations in tissue material properties were used to obtain refined values of five key material parameters. The relaxation of the force in the three bath concentrations was exponential in form, expressed as mean compressive force loss of 48.7, 55.0, and 140 N, respectively, with time constants of 1.73, 2.78, and 3.40 h. This behavior was analytically well represented by a model having poroelastic and osmotic tissue properties with published tissue properties adjusted by multiplying factors between 0.55 and 2.6. Force relaxation and time constants from the analytical simulations were most sensitive to values of fixed charge density and endplate porosity. PMID:20711754

  13. Varied Clinical Manifestations of Amebic Colitis.

    PubMed

    Cooper, Chad J; Fleming, Rhonda; Boman, Darius A; Zuckerman, Marc J

    2015-11-01

    Invasive amebiasis is common worldwide, but infrequently observed in the United States. It is associated with considerable morbidity in patients residing in or traveling to endemic areas. We review the clinical and endoscopic manifestations of amebic colitis to alert physicians to the varied clinical manifestations of this potentially life-threatening disease. Copyright ©Most patients present with watery or bloody diarrhea. Less common presentations of amebic colitis include abdominal pain, overt gastrointestinal bleeding, exacerbation of inflammatory bowel disease, or the incidental association with colon cancer. Amebic liver abscesses are the most frequent complication. Rectosigmoid involvement may be found on colonoscopy; however, most case series have reported that the cecum is the most commonly involved site, followed by the ascending colon. Endoscopic evaluation should be used to assist in the diagnosis, with attention to the observation of colonic inflammation, ulceration, and amebic trophozoites on histopathological examination. PMID:26539949

  14. Violent and criminal manifestations in dementia patients.

    PubMed

    Cipriani, Gabriele; Lucetti, Claudio; Danti, Sabrina; Carlesi, Cecilia; Nuti, Angelo

    2016-05-01

    Although the older adults have been studied as victims of violence, geriatric patients can display violent behavior. The purpose of the present review was to explore the phenomenon of criminal violations and violent acts in people with dementia. The authors used PubMed to search the MEDLINE database and other sources for original research and review articles on criminal and violent manifestation in demented patients combining the terms "criminal manifestation," "violence, aggressive behavior," "homicide," "suicide" and "homicide-suicide" together with "dementia". Possible biomarkers of violence are considered. The present review highlights the risk factors for violence in patients suffering from dementia, and reviews the literature about criminal violations and homicidal/suicidal behavior in this patient group. Geriatr Gerontol Int 2016; 16: 541-549. PMID:26460091

  15. Familial polyposis coli and its extracolonic manifestations.

    PubMed

    Cohen, S B

    1982-06-01

    A detailed clinical study of 30 families with familial polyposis coli is presented. Seven 'isolated' cases are also described. It was found that some families did not exhibit any extracolonic manifestations, but the majority of families showed various numbers of members who had these manifestations of differing types and degrees. In view of the great variability within the members of a family, polyposis coli and the Gardner syndrome are probably both produced by one pleiotropic gene. The occurrence of other neoplastic phenomena in association with polyposis coli has been considered. Many types of malignancy can occur in these patients and their families and the majority are probably fortuitous. The consistent finding of an association with medulloblastoma is such as to make this association of significance, but no reason is known for this. It is suggested that the term 'Turcot syndrome' should be used in a more restrictive manner than at present. PMID:7108915

  16. Clinical Manifestations and Diagnosis of Acromegaly

    PubMed Central

    Lugo, Gloria; Pena, Lara; Cordido, Fernando

    2012-01-01

    Acromegaly and gigantism are due to excess GH production, usually as a result of a pituitary adenoma. The incidence of acromegaly is 5 cases per million per year and the prevalence is 60 cases per million. Clinical manifestations in each patient depend on the levels of GH and IGF-I, age, tumor size, and the delay in diagnosis. Manifestations of acromegaly are varied and include acral and soft tissue overgrowth, joint pain, diabetes mellitus, hypertension, and heart and respiratory failure. Acromegaly is a disabling disease that is associated with increased morbidity and reduced life expectancy. The diagnosis is based primarily on clinical features and confirmed by measuring GH levels after oral glucose loading and the estimation of IGF-I. It has been suggested that the rate of mortality in patients with acromegaly is correlated with the degree of control of GH. Adequately treated, the relative mortality risk can be markedly reduced towards normal. PMID:22518126

  17. [Pulmonary manifestations of connective tissue diseases].

    PubMed

    Rehbock, B

    2015-03-01

    Systemic autoimmune diseases are responsible for about 25% of all deaths due to interstitial lung disease; therefore, an early identification of patients with pulmonary manifestation changes the management. Detection, differential diagnostic classification and staging of the pneumological pattern of findings are largely based on high-resolution computed tomography (HR-CT). The main differential diagnostic challenges are interstitial manifestations which present with radiological-histopathological phenotypes of interstitial pneumonia. The most common form of interstitial pulmonary reaction form of connective tissue diseases is the nonspecific interstitial pneumonia (NSIP) pattern. In rheumatoid arthritis, a usual interstitial pneumonia (UIP) pattern is dominant. Uncharacteristic reactions of airways and pleura can be the leading symptom or present as accompanying findings. A serious complication is pulmonary hypertension. Drug-induced lung lesions can present with similar HR-CT morphology as connective tissue diseases and can only be differentiated in the temporal and clinical context. PMID:25693496

  18. The Chronic Gastrointestinal Manifestations of Chagas Disease

    PubMed Central

    Matsuda, Nilce Mitiko; Miller, Steven M.; Evora, Paulo R. Barbosa

    2009-01-01

    Chagas disease is an infectious disease caused by the protozoan Trypanosoma cruzi. The disease mainly affects the nervous system, digestive system and heart. The objective of this review is to revise the literature and summarize the main chronic gastrointestinal manifestations of Chagas disease. The chronic gastrointestinal manifestations of Chagas disease are mainly a result of enteric nervous system impairment caused by T. cruzi infection. The anatomical locations most commonly described to be affected by Chagas disease are salivary glands, esophagus, lower esophageal sphincter, stomach, small intestine, colon, gallbladder and biliary tree. Chagas disease has also been studied in association with Helicobacter pylori infection, interstitial cells of Cajal and the incidence of gastrointestinal cancer. PMID:20037711

  19. Real-life contextual manifestations of wisdom.

    PubMed

    Yang, Shih-Ying

    2008-01-01

    Wisdom pertains to managing human affairs, and it arises in highly contextualized situations. The present study aims to investigate manifestations of wisdom in real-life contexts through semi-structured interviews with 66 individuals nominated as wise persons. All nominees were ethnic Chinese from Taiwan, an East Asian country which has Confucianism, Taoism, and Buddhism as its predominant philosophies. Analysis of these interview transcripts yielded 220 wisdom incidents that fall into five categories of wisdom. Results of the present study suggests that in real life, wisdom most likely is manifested through: 1) striving for common good by helping others and contributing to society; 2) achieving and maintaining a satisfactory state of life; 3) deciding and developing life paths; 4) resolving difficult problems at work; and 5) insisting on doing the right thing when facing adversity. PMID:19266867

  20. Maxillary sinus manifestations of methamphetamine abuse.

    PubMed

    Faucett, Erynne A; Marsh, Katherine M; Farshad, Kayven; Erman, Audrey B; Chiu, Alexander G

    2015-01-01

    Methamphetamines are the second most commonly used illicit drug worldwide and cost the United States health-care system ∼$23.4 billion annually. Use of this drug affects multiple organ systems and causes a variety of clinical manifestations. Although there are commonly known sequelae of methamphetamine abuse such as "meth mouth," there is limited evidence regarding maxillary sinus manifestations. The following cases highlight the initial evaluation and management of two methamphetamine abusers with loculated purulent collections within the maxillary sinus as a result of methamphetamine abuse. Our aim was to delineate the otolaryngologic symptoms associated with the patients' methamphetamine abuse. Computed tomography and magnetic resonance imaging studies revealed loculated purulent collections within the maxillary sinus of probable odontogenic origin in both patients. Methamphetamine abuse leading to rampant caries and poor oral hygiene may predispose individuals for craniofacial infections and fluid collections. These cases illustrate the development of maxillary sinusitis and maxilla mucoceles that have been associated with methamphetamine use. PMID:25675268

  1. [Cardiac sarcoidosis - clinical manifestation and diagnosis].

    PubMed

    Błaut-Jurkowska, Justyna; Podolec, Piotr; Olszowska, Maria

    2016-08-01

    Sarcoidosis is a multisystem inflammatory disease defined histologically by the formation of noncaseating granulomas. The etiology of sarcoidosis remains unknown. Heart involvement in the course of sarcoidosis concerns about 5% of patients. The most common manifestation of cardiac sarcoidosis are conduction abnormalities, arrhythmias and heart failure. The diagnostic algorithm includes performing a clinical history, a 12-lead electrocardiogram (ECG) and an echocardiogram. If any of the initial screening investigations yields an abnormality, diagnostics should be continue using advanced imaging techniques: cardiovascular magnetic resonance (CMR) or fluorodeoxyglucose positron emission tomography (FDG-PET). Nowadays endomyocardial biopsy is not performed routinely.The clinical picture of cardiac sarcoidosis is highly variable. Screening for cardiac sarcoidosis should be performed in all patients diagnosed with extracardiac sarcoidosis. Cardiac sarcoidosis should also be suspected in young patients without a diagnosis of sarcoidosis who present with conduction abnormalities of unknown etiology, because cardiac sarcoidosis may be the first or the only manifestation of the disease. PMID:27591449

  2. [Cardiac sarcoidosis - clinical manifestation and diagnosis].

    PubMed

    Błaut-Jurkowska, Justyna; Podolec, Piotr; Olszowska, Maria

    2016-07-01

    Sarcoidosis is a multisystem inflammatory disease defined histologically by the formation of noncaseating granulomas. The etiology of sarcoidosis remains unknown. Heart involvement in the course of sarcoidosis concerns about 5% of patients. The most common manifestation of cardiac sarcoidosis are conduction abnormalities, arrhythmias and heart failure. The diagnostic algorithm includes performing a clinical history, a 12-lead electrocardiogram (ECG) and an echocardiogram. If any of the initial screening investigations yields an abnormality, diagnostics should be continue using advanced imaging techniques: cardiovascular magnetic resonance (CMR) or fluorodeoxyglucose positron emission tomography (FDG-PET). Nowadays endomyocardial biopsy is not performed routinely.The clinical picture of cardiac sarcoidosis is highly variable. Screening for cardiac sarcoidosis should be performed in all patients diagnosed with extracardiac sarcoidosis. Cardiac sarcoidosis should also be suspected in young patients without a diagnosis of sarcoidosis who present with conduction abnormalities of unknown etiology, because cardiac sarcoidosis may be the first or the only manifestation of the disease. PMID:27590654

  3. Cardiac manifestations of idiopathic pulmonary fibrosis

    PubMed Central

    Agrawal, Abhinav; Verma, Isha; Shah, Varun; Agarwal, Abhishek; Sikachi, Rutuja R

    2016-01-01

    Summary Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, parenchymal disease of the lung with an estimated prevalence of 14–43 per 100,000. Patient usually presents with coughing and exertional dyspnea, which can lead to acute respiratory failure. IPF has been associated with various co-morbidities such as lung cancer, emphysema, obstructive sleep apnea (OSA), GERD and multiple cardiovascular consequences. The cardiovascular manifestations of IPF include pulmonary hypertension, heart failure, coronary artery disease, cardiac arrhythmias & cardiac manifestations of drugs used to treat IPF. This review will outline evidence of the association between IPF and cardiovascular conditions and attempt to provide insights into the underlying pathophysiology. We also discuss the impact of these cardiovascular diseases on patients with IPF including increased morbidity and mortality. PMID:27195188

  4. Cardiac manifestations of idiopathic pulmonary fibrosis.

    PubMed

    Agrawal, Abhinav; Verma, Isha; Shah, Varun; Agarwal, Abhishek; Sikachi, Rutuja R

    2016-05-01

    Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, parenchymal disease of the lung with an estimated prevalence of 14-43 per 100,000. Patient usually presents with coughing and exertional dyspnea, which can lead to acute respiratory failure. IPF has been associated with various co-morbidities such as lung cancer, emphysema, obstructive sleep apnea (OSA), GERD and multiple cardiovascular consequences. The cardiovascular manifestations of IPF include pulmonary hypertension, heart failure, coronary artery disease, cardiac arrhythmias & cardiac manifestations of drugs used to treat IPF. This review will outline evidence of the association between IPF and cardiovascular conditions and attempt to provide insights into the underlying pathophysiology. We also discuss the impact of these cardiovascular diseases on patients with IPF including increased morbidity and mortality. PMID:27195188

  5. Imaging lung manifestations of HIV/AIDS

    PubMed Central

    Allen, Carolyn M.; AL-Jahdali, Hamdan H.; Irion, Klaus L.; Al Ghanem, Sarah; Gouda, Alaa; Khan, Ali Nawaz

    2010-01-01

    Advances in our understanding of human immunodeficiency virus (HIV) infection have led to improved care and incremental increases in survival. However, the pulmonary manifestations of HIV/acquired immunodeficiency syndrome (AIDS) remain a major cause of morbidity and mortality. Respiratory complaints are not infrequent in patients who are HIV positive. The great majority of lung complications of HIV/AIDS are of infectious etiology but neoplasm, interstitial pneumonias, Kaposi sarcoma and lymphomas add significantly to patient morbidity and mortality. Imaging plays a vital role in the diagnosis and management of lung of complications associated with HIV. Accurate diagnosis is based on an understanding of the pathogenesis of the processes involved and their imaging findings. Imaging also plays an important role in selection of the most appropriate site for tissue sampling, staging of disease and follow-ups. We present images of lung manifestations of HIV/AIDS, describing the salient features and the differential diagnosis. PMID:20981180

  6. Atypical Manifestations in Glut1 Deficiency Syndrome.

    PubMed

    De Giorgis, V; Varesio, C; Baldassari, C; Piazza, E; Olivotto, S; Macasaet, J; Balottin, U; Veggiotti, P

    2016-08-01

    Glucose transporter type 1 deficiency syndrome is a genetically determined, treatable, neurologic disorder that is caused by an insufficient transport of glucose into the brain. It is caused by a mutation in the SCL2A1 gene, which is so far the only known to be associated with this condition. Glucose transporter type 1 deficiency syndrome consists of a wide clinical spectrum that usually presents with cognitive impairment, epilepsy, paroxysmal exercise-induced dyskinesia, acquired microcephaly, hemolytic anemia, gait disturbance, and dyspraxia in different combinations. However, there are other clinical manifestations that we consider equally peculiar but that have so far been poorly described in literature. In this review, supported by a video contribution, we will accurately describe this type of clinical manifestation such as oculogyric crises, weakness, paroxysmal kinesigenic and nonkinesigenic dyskinesia in order to provide an additional instrument for a correct, rapid diagnosis. PMID:27250207

  7. Three-axis lever actuator with flexure hinges for an optical disk system

    NASA Astrophysics Data System (ADS)

    Han, Chang-Soo; Kim, Soo-Hyun

    2002-10-01

    A three-axis lever actuator with a flexure hinge has been designed and fabricated. This actuator is driven by electromagnetic force based on a coil-magnet system and can be used as a high precision actuator and, especially as a pickup head actuator in optical disks. High precision and low sensitivity to external vibration are the major advantages of this lever actuator. An analysis model was found and compared to the finite element method. Dynamic characteristics of the three-axis lever actuator were measured. The results are in very close agreement to those predicted by the model and finite element analysis.

  8. Secular Evolution in Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Kormendy, John

    2013-10-01

    Self-gravitating systems evolve toward the most tightly bound configuration that is reachable via the evolution processes that are available to them. They do this by spreading -- the inner parts shrink while the outer parts expand -- provided that some physical process efficiently transports energy or angular momentum outward. The reason is that self-gravitating systems have negative specific heats. As a result, the evolution of stars, star clusters, protostellar and protoplanetary disks, black hole accretion disks and galaxy disks are fundamentally similar. How evolution proceeds then depends on the evolution processes that are available to each kind of self-gravitating system. These processes and their consequences for galaxy disks are the subjects of my lectures and of this Canary Islands Winter School. I begin with a review of the formation, growth and death of bars. Then I review the slow (`secular') rearrangement of energy, angular momentum, and mass that results from interactions between stars or gas clouds and collective phenomena such as bars, oval disks, spiral structure and triaxial dark haloes. The `existence-proof' phase of this work is largely over: we have a good heuristic understanding of how nonaxisymmetric structures rearrange disk gas into outer rings, inner rings and stuff dumped onto the centre. The results of simulations correspond closely to the morphology of barred and oval galaxies. Gas that is transported to small radii reaches high densities. Observations confirm that many barred and oval galaxies have dense central concentrations of gas and star formation. The result is to grow, on timescales of a few Gyr, dense central components that are frequently mistaken for classical (elliptical-galaxy-like) bulges but that were grown slowly out of the disk (not made rapidly by major mergers). The resulting picture of secular galaxy evolution accounts for the richness observed in galaxy structure. We can distinguish between classical and pseudo

  9. Imaging of Spinal Manifestations of Hematological Disorders.

    PubMed

    Pawha, Puneet S; Chokshi, Falgun H

    2016-08-01

    Imaging manifestations of hematological diseases and their potential complications are broad, and there may be significant overlap in features of various disease processes. Knowledge of appropriate choice of imaging test, pertinent imaging patterns, and pathophysiology of disease can help the reader increase specificity in the diagnosis and treatment of the patient. Most importantly, we encourage readers of this review to engage their radiologists during the diagnostic, treatment, and management phases of care delivery. PMID:27444004

  10. Rheumatic manifestations of inflammatory bowel disease.

    PubMed

    Rodríguez-Reyna, Tatiana Sofía; Martínez-Reyes, Cynthia; Yamamoto-Furusho, Jesús Kazúo

    2009-11-28

    This article reviews the literature concerning rheumatic manifestations of inflammatory bowel disease (IBD), including common immune-mediated pathways, frequency, clinical course and therapy. Musculoskeletal complications are frequent and well-recognized manifestations in IBD, and affect up to 33% of patients with IBD. The strong link between the bowel and the osteo-articular system is suggested by many clinical and experimental observations, notably in HLA-B27 transgenic rats. The autoimmune pathogenic mechanisms shared by IBD and spondyloarthropathies include genetic susceptibility to abnormal antigen presentation, aberrant recognition of self, the presence of autoantibodies against specific antigens shared by the colon and other extra-colonic tissues, and increased intestinal permeability. The response against microorganisms may have an important role through molecular mimicry and other mechanisms. Rheumatic manifestations of IBD have been divided into peripheral arthritis, and axial involvement, including sacroiliitis, with or without spondylitis, similar to idiopathic ankylosing spondylitis. Other periarticular features can occur, including enthesopathy, tendonitis, clubbing, periostitis, and granulomatous lesions of joints and bones. Osteoporosis and osteomalacia secondary to IBD and iatrogenic complications can also occur. The management of the rheumatic manifestations of IBD consists of physical therapy in combination with local injection of corticosteroids and nonsteroidal anti-inflammatory drugs; caution is in order however, because of their possible harmful effects on intestinal integrity, permeability, and even on gut inflammation. Sulfasalazine, methotrexate, azathioprine, cyclosporine and leflunomide should be used for selected indications. In some cases, tumor necrosis factor-alpha blocking agents should be considered as first-line therapy. PMID:19938189

  11. 40 CFR 264.72 - Manifest discrepancies.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... limits for “empty” containers set forth in 40 CFR 261.7(b). (b) Significant differences in quantity are... exceeds the quantity limits for “empty” containers set forth in 40 CFR 261.7(b), the facility must consult... set forth in 40 CFR 261.7(b) after it has signed, dated, and returned a copy of the manifest to...

  12. Peripheral Nervous System Manifestations of Infectious Diseases

    PubMed Central

    Brizzi, Kate T.

    2014-01-01

    Infectious causes of peripheral nervous system (PNS) disease are underrecognized but potentially treatable. Heightened awareness educed by advanced understanding of the presentations and management of these infections can aid diagnosis and facilitate treatment. In this review, we discuss the clinical manifestations, diagnosis, and treatment of common bacterial, viral, and parasitic infections that affect the PNS. We additionally detail PNS side effects of some frequently used antimicrobial agents. PMID:25360209

  13. 40 CFR 264.72 - Manifest discrepancies.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... limits for “empty” containers set forth in 40 CFR 261.7(b). (b) Significant differences in quantity are... exceeds the quantity limits for “empty” containers set forth in 40 CFR 261.7(b), the facility must consult... set forth in 40 CFR 261.7(b) after it has signed, dated, and returned a copy of the manifest to...

  14. Dermatologic Extrahepatic Manifestations of Hepatitis C

    PubMed Central

    Dedania, Bhavtosh; Wu, George Y.

    2015-01-01

    Hepatitis C virus (HCV) affects millions of people worldwide, and an estimated 3.2 million people in the United States. HCV is a hepatotropic and lymphotropic virus that causes not only liver disease, but also a significant number of extrahepatic manifestations (EHMs). Up to 74% of patients affected by HCV will have HCV-related EHMs of some severity in their lifetime. The EHMs vary from simple cutaneous palpable purpura to complex lymphoproliferative disorders, including lymphomas and immune-complex deposit diseases causing local and/or systemic complications. Mixed cryoglobulinemia (MC) is manifested by multiple systemic organ involvement, mainly skin, kidney, peripheral nerves, and salivary glands, and less frequently causes widespread vasculitis and malignant lymphoma. MC affects up to 3% of HCV-infected patients with cryoglobulinemia of clinical significance, i.e. >6%. Severe disease requires immunosuppressive or plasma exchange therapy. HCV prevalence in the United States in patients with porphyria cutanea tarda (PCT) was reported to be 66%, much higher than that in general population. Therefore, all patients with PCT should be screened for HCV. The skin rash of PCT varies from large blisters to small vesicles and/or milia on the hands. Skin manifestations due to PCT usually respond to anti‐HCV treatment together with reducing skin sun exposure, avoiding triggers, having routine phlebotomy (especially for people with chronic iron overload states), and using chloroquine. Lichen planus (LP), which typically affects both the skin and oral mucosa is a chronic inflammatory disease of squamous cell origin affecting about 1% of the worldwide population. The prevalence of HCV in patients with LP varies based on geographic location. We review here the basic pathophysiology, clinical features, and management of dermatologic manifestations of HCV. PMID:26357639

  15. An Observational Perspective of Transitional Disks

    NASA Astrophysics Data System (ADS)

    Espaillat, C.; Muzerolle, J.; Najita, J.; Andrews, S.; Zhu, Z.; Calvet, N.; Kraus, S.; Hashimoto, J.; Kraus, A.; D'Alessio, P.

    Transitional disks are objects whose inner disk regions have undergone substantial clearing. The Spitzer Space Telescope produced detailed spectral energy distributions (SEDs) of transitional disks that allowed us to infer their radial dust disk structure in some detail, revealing the diversity of this class of disks. The growing sample of transitional disks also opened up the possibility of demographic studies, which provided unique insights. There now exist (sub)millimeter and infrared images that confirm the presence of large clearings of dust in transitional disks. In addition, protoplanet candidates have been detected within some of these clearings. Transitional disks are thought to be a strong link to planet formation around young stars and are a key area to study if further progress is to be made on understanding the initial stages of planet formation. Here we provide a review and synthesis of transitional disk observations to date with the aim of providing timely direction to the field, which is about to undergo its next burst of growth as the Atacama Large Millimeter/submillimeter Array (ALMA) reaches its full potential. We discuss what we have learned about transitional disks from SEDs, color-color diagrams, and imaging in the (sub)millimeter and infrared. We note the limitations of these techniques, particularly with respect to the sizes of the clearings currently detectable, and highlight the need for pairing broadband SEDs with multi-wavelength images to paint a more detailed picture of transitional disk structure. We review the gas in transitional disks, keeping in mind that future observations with ALMA will give us unprecedented access to gas in disks, and also observed infrared variability pointing to variable transitional disk structure, which may have implications for disks in general. We then distill the observations into constraints for the main disk-clearing mechanisms proposed to date (i.e., photoevaporation, grain growth, and companions) and

  16. Chronic polyarthritis as isolated manifestation of toxocariasis.

    PubMed

    Viola, Gabriela R; Giacomin, Maria Fernanda A; França, Camila M P; Sallum, Adriana M E; Jacob, Cristina M A; Silva, Clovis A

    2016-01-01

    Human toxocariasis is a parasitic zoonosis mainly caused by Toxocara canis or Toxocara cati and is acquired by ingestion of the parasite's embryonated eggs. Arthralgia and/or arthritis were reported in up to 17% of the cases, generally with acute duration (less than 6 weeks). However, to our knowledge, chronic polyarthritis, as the isolated presentation of Toxocara infection, was not reported. One of the 5809 patients that was followed up at our service (0.017%) had chronic polyarthritis as the single manifestation of toxocariasis and was described herein. A 3-year-old girl was referred to our service with severe painful chronic polyarthritis for a period longer than 10 weeks and morning stiffness of 30min. Dog contact exposure history in the recreational areas of neighborhood was reported. Her exams showed high levels of eosinophils in peripheral blood (29%), bone marrow aspirate revealed marked eosinophilia (32%) and Toxocara enzyme-linked immunosorbent assay (Elisa) was positive (1:1280). She was treated with paracetamol (40mg/kg/day) and thiabendazole (25mg/kg/day) for 10 days, and all manifestations reduced. After eight months of follow-up, she was on clinical and laboratorial remission. In conclusion, we described a case of chronic polyarthritis, as isolated manifestation of toxocariasis, mimicking juvenile idiopathic arthritis and leukemia. Importantly, this zoonosis should be considered in patients with arthritis and eosinophilia. PMID:27267534

  17. Cutaneous Manifestations of Common Liver Diseases

    PubMed Central

    Dogra, Sunil; Jindal, Rashmi

    2012-01-01

    Skin functions as a window to our overall health and a number of systemic diseases result in various cutaneous changes. Knowledge of these manifestations helps in suspecting an underlying systemic illness. Cutaneous abnormalities are quite common in patients with liver diseases and this article aims to focus on these dermatoses. Cutaneous manifestations seen in patients with liver disease though common are nonspecific. They can also be seen in patients without liver diseases and generally do not indicate about a specific underlying hepatic disorder. The presence of a constellation of signs and symptoms is more useful in pointing toward an underlying hepatobiliary condition. The commonest symptom in patients with liver disease is pruritus which is often protracted and disabling. Other common features include spider angiomas, palmar erythema, paper money skin, xanthelasmas, pigmentary changes, and nutritional deficiencies. In this article, first the common cutaneous manifestations that may be associated with liver disorders are discussed and then common liver diseases with their specific cutaneous findings are discussed. Cutaneous abnormalities may be the first clue to the underlying liver disease. Identifying them is crucial for early diagnosis and better management. PMID:25755383

  18. Rare Neurological Manifestation of Celiac Disease

    PubMed Central

    Rani, Uzma; Imdad, Aamer; Beg, Mirza

    2015-01-01

    Celiac disease (CD) is an immune-mediated disease characterized by permanent gastrointestinal tract sensitivity to gluten in genetically predisposed individuals. It has varied clinical manifestations, ranging from gastrointestinal to extraintestinal, including neurological, skin, reproductive and psychiatric symptoms, which makes its diagnosis difficult and challenging. Known neurological manifestations of CD include epilepsy with or without occipital calcification, attention deficit hyperactivity disorder and ataxia, headache, neuropathies and behavior disorders. We present the case of a 14-year-old female with headaches and blurred vision for 1 year; she was noted to have papilledema on ophthalmic examination with increased cerebrospinal fluid opening pressure on lumber puncture and was diagnosed as a case of pseudotumor cerebri (PTC). Meanwhile her workup for chronic constipation revealed elevated tissue transglutaminase IgA and antiendomysial IgA antibodies. Upper gastrointestinal endoscopy with duodenal biopsy confirmed the diagnosis of CD. The patient was started on a gluten-free diet, leading to resolution of not only gastrointestinal symptoms but also to almost complete resolution of symptoms of PTC. This report describes the correlation of CD and PTC as its neurological manifestation. PMID:26120302

  19. Skin Manifestations of Inflammatory Bowel Disease

    PubMed Central

    Huang, Brian L.; Chandra, Stephanie; Shih, David Quan

    2012-01-01

    Inflammatory bowel disease (IBD) is a disease that affects the intestinal tract via an inflammatory process. Patients who suffer from IBD often have diseases that affect multiple other organ systems as well. These are called extraintestinal manifestations and can be just as, if not more debilitating than the intestinal inflammation itself. The skin is one of the most commonly affected organ systems in patients who suffer from IBD. The scientific literature suggests that a disturbance of the equilibrium between host defense and tolerance, and the subsequent over-activity of certain immune pathways are responsible for the cutaneous disorders seen so frequently in IBD patients. The purpose of this review article is to give an overview of the types of skin diseases that are typically seen with IBD and their respective pathogenesis, proposed mechanisms, and treatments. These cutaneous disorders can manifest as metastatic lesions, reactive processes to the intestinal inflammation, complications of IBD itself, or side effects from IBD treatments; these can be associated with IBD via genetic linkage, common autoimmune processes, or other mechanisms that will be discussed in this article. Ultimately, it is important for healthcare providers to understand that skin manifestations should always be checked and evaluated for in patients with IBD. Furthermore, skin disorders can predate gastrointestinal symptoms and thus may serve as important clinical indicators leading physicians to earlier diagnosis of IBD. PMID:22347192

  20. Mitochondrial DNA, mitochondrial dysfunction, and cardiac manifestations.

    PubMed

    Lee, Sung Ryul; Kim, Nari; Noh, Yeonhee; Xu, Zhelong; Ko, Kyung Soo; Rhee, Byoung Doo; Han, Jin

    2016-01-01

    Mitochondria, the powerhouses of cells, have their own DNA (mtDNA). They regulate the transport of metabolites and ions, which determine cell physiology, survival, and death. Mitochondrial dysfunction, including impaired oxidative phosphorylation, preferentially affects heart function via imbalance of energy supply and demand. Recently, mitochondrial mutations and associated mitochondrial dysfunction were suggested as a causal factor of cardiac manifestations. Oxidative stress largely influences mtDNA stability due to oxidative modifications of mtDNA. Furthermore, the continuous replicative state of mtDNA and presence of minimal nucleoid structure render mitochondria vulnerable to oxidative damage and subsequent mutations, which impair mitochondrial functions. However, the occurrence of mtDNA heteroplasmy in the same mitochondrion or cell and presence of nuclear DNA-encoded mtDNA repair systems raise questions regarding whether oxidative stress-mediated mtDNA mutations are the major driving force in accumulation of mtDNA mutations. Here, we address the possible causes of mitochondrial DNA mutations and their involvement in cardiac manifestations. Current strategies for treatment related to mitochondrial mutations and/or dysfunction in cardiac manifestations are briefly discussed. PMID:27100514

  1. Mandibular and Dental Manifestations of Gaucher Disease

    PubMed Central

    Saranjam, Hamid R.; Sidransky, Ellen; Levine, William Z.; Zimran, Ari; Elstein, Deborah

    2012-01-01

    Gaucher disease is a systemic lysosomal storage disorder with a high prevalence among Ashkenazi Jews. It is caused by an inherited deficiency of the lysosomal enzyme glucocerebrosidase. Common signs and symptoms include hepatosplenomegaly, anemia, thrombocytopenia, and skeletal involvement. Oral and dental manifestations are less commonly seen. These manifestations are often asymptomatic, although they may be detected by routine dental x-rays. There are several case reports and a few larger series published describing patients with Gaucher disease who have mandibulo-maxillofacial involvement. This review aims to examine the oral manifestations observed in Gaucher disease and to suggest practical guidelines for dealing with these often worrisome signs. Among the critical issues are the benign nature of Gaucher cell infiltration of the mandible and the critical importance of being prepared for post-procedure bleeding and/or infections. Therefore, it is essential that dental practitioners be aware of the possible oral and dental complications of Gaucher disease, as well as the available treatment modalities. PMID:22251146

  2. Polarization Complicates Images of Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Jang-Condell, Hannah

    2016-01-01

    A popular method for obtaining high-contrast images of gas-rich optically thick protoplanetary disks around young stars is polarimetric imaging. The rationale for this is that light scattered off the disk surface is preferentially polarized, while light emitted directly from the star is not. Polarimetric imaging has resulted in images of disk surfaces that show morphological complexity, such as gaps, spiral arms, and dark spots. However, these images need to be interpreted with care, because as the angle of scattering varies across the surface of an inclined disk, so does the polarization fraction vary. We present simulated images of disks in scattered polarized light, showing that a relatively simple structure, such as an axisymmetric gap, can give the appearance of more complex asymmetric structure when the disk is inclined. This demonstrates that polarimetric imaging must be interpreted with great caution.

  3. Residual stress and plastic anisotropy in indented 2024-T351 aluminum disks

    SciTech Connect

    Clausen, Bjorn; Prime, Michael B; Saurabh, Kabra; Brown, Donald W; Pagliaro, Pierluigi; Backlund, Peter; Shaw, Sanjiv; Criss, Everett

    2009-01-01

    Recent studies have proven that generating a well defined residual stress state using the indented disk approach is an excellent way to validate experimental and modeling techniques for measuring and predicting residual stresses. The previous studies dealt with indented stainless steel disks, and included experimental determination of residual stresses using the Contour Method and neutron diffraction measurements. The measured residual stress states showed good agreement between the techniques, and a Finite Element Model predicted residual stress state based upon material properties determined form standard tension and compression/tension tests was also in good agreement with the measurements. In the present work, disks of 2024-T351 Aluminum were investigated. As before, the residual stress profile was measured using neutron diffraction and the Contour Method and Finite Element Modeling was employed to predict the residual stress profile. Analysis and comparison of the three techniques were complicated by the fact that the experimental data shows evidence of plastic anisotropy and strong Bauschinger effect within the indented disks.

  4. Development of an advanced actuator disk model for Large-Eddy Simulation of wind farms

    NASA Astrophysics Data System (ADS)

    Moens, Maud; Duponcheel, Matthieu; Winckelmans, Gregoire; Chatelain, Philippe

    2015-11-01

    This work aims at improving the fidelity of the wind turbine modelling for Large-Eddy Simulation (LES) of wind farms, in order to accurately predict the loads, the production, and the wake dynamics. In those simulations, the wind turbines are accounted for through actuator disks. i.e. a body-force term acting over the regularised disk swept by the rotor. These forces are computed using the Blade Element theory to estimate the normal and tangential components (based on the local simulated flow and the blade characteristics). The local velocities are modified using the Glauert tip-loss factor in order to account for the finite number of blades; the computation of this correction is here improved thanks to a local estimation of the effective upstream velocity at every point of the disk. These advanced actuator disks are implemented in a 4th order finite difference LES solver and are compared to a classical Blade Element Momentum method and to high fidelity wake simulations performed using a Vortex Particle-Mesh method in uniform and turbulent flows.

  5. Planet-Disk Interaction on the GPU: The FARGO3D code

    NASA Astrophysics Data System (ADS)

    Masset, F. S.; Benítez-Llambay, P.

    2015-10-01

    We present the new code FARGO3D. It is a finite difference code that solves the equations of hydrodynamics or magnetohydrodynamics on a Cartesian, cylindrical or spherical mesh. It features orbital advection, conserves mass and (angular) momentum to machine accuracy. Special emphasis is put on the description of planet disk tidal interactions. It is parallelized with MPI, and it can run indistinctly on CPUs or GPUs, without the need to program in a GPU oriented language.

  6. A Semi-Analytical Solution for Elastic Analysis of Rotating Thick Cylindrical Shells with Variable Thickness Using Disk Form Multilayers

    PubMed Central

    Zamani Nejad, Mohammad; Jabbari, Mehdi; Ghannad, Mehdi

    2014-01-01

    Using disk form multilayers, a semi-analytical solution has been derived for determination of displacements and stresses in a rotating cylindrical shell with variable thickness under uniform pressure. The thick cylinder is divided into disk form layers form with their thickness corresponding to the thickness of the cylinder. Due to the existence of shear stress in the thick cylindrical shell with variable thickness, the equations governing disk layers are obtained based on first-order shear deformation theory (FSDT). These equations are in the form of a set of general differential equations. Given that the cylinder is divided into n disks, n sets of differential equations are obtained. The solution of this set of equations, applying the boundary conditions and continuity conditions between the layers, yields displacements and stresses. A numerical solution using finite element method (FEM) is also presented and good agreement was found. PMID:24719582

  7. Analytical Solution for Whirling Speeds and Mode Shapes of a Distributed-Mass Shaft With Arbitrary Rigid Disks.

    PubMed

    Wu, Jong-Shyong; Lin, Foung-Tang; Shaw, Huei-Jou

    2014-03-01

    The purpose of this paper is to present an approach for replacing the effects of each rigid disk mounted on the spin shaft by a lumped mass together with a frequency-dependent equivalent mass moment of inertia so that the whirling motion of a rotating shaft-disk system is similar to the transverse free vibration of a stationary beam and the technique for the free vibration analysis of a stationary beam with multiple concentrated elements can be used to determine the forward and backward whirling speeds, along with mode shapes of a distributed-mass shaft carrying arbitrary rigid disks. Numerical results reveal that the characteristics of whirling motions are significantly dependent on the slopes of the associated natural mode shapes at the positions where the rigid disks are located. Furthermore, the results obtained from the presented analytical method and those obtained from existing literature or the finite element method (FEM) are in good agreement. PMID:24891729

  8. Finite-dimensional calculus

    NASA Astrophysics Data System (ADS)

    Feinsilver, Philip; Schott, René

    2009-09-01

    We discuss topics related to finite-dimensional calculus in the context of finite-dimensional quantum mechanics. The truncated Heisenberg-Weyl algebra is called a TAA algebra after Tekin, Aydin and Arik who formulated it in terms of orthofermions. It is shown how to use a matrix approach to implement analytic representations of the Heisenberg-Weyl algebra in univariate and multivariate settings. We provide examples for the univariate case. Krawtchouk polynomials are presented in detail, including a review of Krawtchouk polynomials that illustrates some curious properties of the Heisenberg-Weyl algebra, as well as presenting an approach to computing Krawtchouk expansions. From a mathematical perspective, we are providing indications as to how to implement infinite terms Rota's 'finite operator calculus'.

  9. Finite-Temperature Micromagnetism

    SciTech Connect

    Skomski, R; Kumar, P; Hadjipanayis, GC; Sellmyer, DJ

    2013-07-01

    It is investigated how magnetic hysteresis is affected by finite-temperature excitations, using soft regions in hard-magnetic matrices as model systems. In lowest order, magnetization processes are described by the traditional approach of using finite-temperature materials constants such as K-1(T). Nanoscale excitations are usually small perturbations. For example, a Bloch summation over all magnon wave vectors shows that remanence is slightly enhanced, because long-wavelength excitations are suppressed. However, a reverse magnetic field enhances the effect of thermal excitations and causes a small reduction of the coercivity. To describe such effects, we advocate micromagnetic calculations where finite-temperature fluctuations are treated as small corrections to the traditional approach, as contrasted to full-scale Monte Carlo simulations.

  10. Parameterized reduced order modeling of misaligned stacked disks rotor assemblies

    NASA Astrophysics Data System (ADS)

    Ganine, Vladislav; Laxalde, Denis; Michalska, Hannah; Pierre, Christophe

    2011-01-01

    Light and flexible rotating parts of modern turbine engines operating at supercritical speeds necessitate application of more accurate but rather computationally expensive 3D FE modeling techniques. Stacked disks misalignment due to manufacturing variability in the geometry of individual components constitutes a particularly important aspect to be included in the analysis because of its impact on system dynamics. A new parametric model order reduction algorithm is presented to achieve this goal at affordable computational costs. It is shown that the disks misalignment leads to significant changes in nominal system properties that manifest themselves as additional blocks coupling neighboring spatial harmonics in Fourier space. Consequently, the misalignment effects can no longer be accurately modeled as equivalent forces applied to a nominal unperturbed system. The fact that the mode shapes become heavily distorted by extra harmonic content renders the nominal modal projection-based methods inaccurate and thus numerically ineffective in the context of repeated analysis of multiple misalignment realizations. The significant numerical bottleneck is removed by employing an orthogonal projection onto the subspace spanned by first few Fourier harmonic basis vectors. The projected highly sparse systems are shown to accurately approximate the specific misalignment effects, to be inexpensive to solve using direct sparse methods and easy to parameterize with a small set of measurable eccentricity and tilt angle parameters. Selected numerical examples on an industrial scale model are presented to illustrate the accuracy and efficiency of the algorithm implementation.

  11. HEATING AND COOLING PROTOSTELLAR DISKS

    SciTech Connect

    Hirose, S.; Turner, N. J. E-mail: neal.turner@jpl.nasa.gov

    2011-05-10

    We examine heating and cooling in protostellar disks using three-dimensional radiation-MHD calculations of a patch of the Solar nebula at 1 AU, employing the shearing-box and flux-limited radiation diffusion approximations. The disk atmosphere is ionized by stellar X-rays, well coupled to magnetic fields, and sustains a turbulent accretion flow driven by magnetorotational instability, while the interior is resistive and magnetically dead. The turbulent layers are heated by absorbing the light from the central star and by dissipating the magnetic fields. They are optically thin to their own radiation and cool inefficiently. The optically thick interior in contrast is heated only weakly, by re-emission from the atmosphere. The interior is colder than a classical viscous model and isothermal. The magnetic fields support an extended atmosphere that absorbs the starlight 1.5 times higher than the hydrostatic viscous model. The disk thickness thus measures not the internal temperature, but the magnetic field strength. Fluctuations in the fields move the starlight-absorbing surface up and down. The height ranges between 13% and 24% of the radius over timescales of several orbits, with implications for infrared variability. The fields are buoyant, so the accretion heating occurs higher in the atmosphere than the stresses. The heating is localized around current sheets, caused by magnetorotational instability at lower elevations and by Parker instability at higher elevations. Gas in the sheets is heated above the stellar irradiation temperature, even though accretion is much less than irradiation power when volume averaged. The hot optically thin current sheets might be detectable through their line emission.

  12. First Image of the disk

    NASA Astrophysics Data System (ADS)

    Smith, B.

    2014-09-01

    In 1983 IRAS detected significant infrared excess around four relatively nearby stars: ! Lyrae, ! Piscis Austrini, " Eridani, and # Pictoris. Before the IRAS results had been officially released, Frank Low asked me if the LPL coronagraph (used in the 1980 Saturn ring-plane crossing) might be able to detect the source of the infrared excess. Of the four stars, all but # Pictoris were easily observable from Tucson. I told Frank I would give it a try. Ultimately, the coronagraphic observations failed to reveal anything around the three stars that were observable from Tucson. In April 1984 Rich Terrile and I had an observing run on the 2.5-m du Pont telescope at the Las Campanas Observatory in Chile. We were using the LPL coronagraph and a Caltech CCD camera to examine the close environment around Uranus and Neptune in preparation for the upcoming Voyager 2 encounters with the two planets. I used this opportunity to observe the fourth IRAS star, # Pictoris. A small window was available for me to observe # Pictoris each night before our observations of the planets could begin. In those days image processing capability did not exist at Las Campanas, and so the circumstellar disk around the star was not seen until we returned home and processed the images at LPL and JPL. During follow-up observations the following year I was able to see the disk visually in the coronagraph's eyepiece. I've sometimes wondered how many astronomers have actually seen a circumstellar disk at the eyepiece of a telescope.

  13. Do elliptical galaxies have thick disks?

    NASA Technical Reports Server (NTRS)

    Thomson, R. C.; Wright, A. E.

    1990-01-01

    The authors discuss new evidence which supports the existence of thick disks in elliptical/SO galaxies. Numerical simulations of weak interactions with thick disk systems produce shell structures very similar in appearance to those observed in many shell galaxies. The authors think this model presents a more plausible explanation for the formation of shell structures in elliptical/SO galaxies than does the merger model and, if correct, supports the existence of thick disks in elliptical/SO galaxies.

  14. MOLECULAR GAS IN YOUNG DEBRIS DISKS

    SciTech Connect

    Moor, A.; Abraham, P.; Kiss, Cs.; Juhasz, A.; Kospal, A.; Pascucci, I.; Apai, D.; Henning, Th.; Csengeri, T.; Grady, C.

    2011-10-10

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old ({approx}>8 Myr), gaseous dust disks. From our results, neither primordial origin nor steady secondary production from icy planetesimals can unequivocally explain the presence of CO gas in the disk of HD21997.

  15. Molecular Gas in Young Debris Disks

    NASA Technical Reports Server (NTRS)

    Moor, A.; Abraham, P.; Juhasz, A.; Kiss, Cs.; Pascucci, I.; Kospal, A.; Apai, D.; Henning, T.; Csengeri, T.; Grady, C.

    2011-01-01

    Gas-rich primordial disks and tenuous gas-poor debris disks are usually considered as two distinct evolutionary phases of the circumstellar matter. Interestingly, the debris disk around the young main-sequence star 49 Ceti possesses a substantial amount of molecular gas and possibly represents the missing link between the two phases. Motivated to understand the evolution of the gas component in circumstellar disks via finding more 49 Ceti-like systems, we carried out a CO J = 3-2 survey with the Atacama Pathfinder EXperiment, targeting 20 infrared-luminous debris disks. These systems fill the gap between primordial and old tenuous debris disks in terms of fractional luminosity. Here we report on the discovery of a second 49 Ceti-like disk around the 30 Myr old A3-type star HD21997, a member of the Columba Association. This system was also detected in the CO(2-1) transition, and the reliable age determination makes it an even clearer example of an old gas-bearing disk than 49 Ceti. While the fractional luminosities of HD21997 and 49 Ceti are not particularly high, these objects seem to harbor the most extended disks within our sample. The double-peaked profiles of HD21997 were reproduced by a Keplerian disk model combined with the LIME radiative transfer code. Based on their similarities, 49 Ceti and HD21997 may be the first representatives of a so far undefined new class of relatively old > or approx.8 Myr), gaseous dust disks. From our results, neither primordia1 origin nor steady secondary production from icy planetesima1s can unequivocally explain the presence of CO gas in the disk ofHD21997.

  16. Accretion disk thermal instability in galactic nuclei

    NASA Technical Reports Server (NTRS)

    Mineshige, S.; Shields, G. A.

    1990-01-01

    The nonlinear evolution and spatial propagation of the thermal instability in accretion disks in galactic nuclei are investigated. Integrations of the vertical structure of the disks are described for different alpha prescriptions, and the thermal stability is examined. Global time-dependent calculations of the unstable disks are performed which show that there are two distinct types of behavior according to the assumed prescription for the viscosity parameter: the 'purr' type and the 'roar' type. The roar type is analyzed in some detail.

  17. Self-similar relativistic disks with pressure

    NASA Astrophysics Data System (ADS)

    Lemos, Jose P. S.

    1989-09-01

    Solutions for disks in equilibrium specified by a constant velocity of rotation and constant velocity dispersions are found. The fluid is not perfect because the stress tensor is anisotropic. These disks are self-similar if they are of infinite extent. The solutions are exact when an equal number of particles move in each sense of rotation so that there is no dragging of the inertial frames. For disks rotating with a small velocity a WKB approximation is used to obtain solutions.

  18. Evaluation of powder metallurgy superalloy disk materials

    NASA Technical Reports Server (NTRS)

    Evans, D. J.

    1975-01-01

    A program was conducted to develop nickel-base superalloy disk material using prealloyed powder metallurgy techniques. The program included fabrication of test specimens and subscale turbine disks from four different prealloyed powders (NASA-TRW-VIA, AF2-1DA, Mar-M-432 and MERL 80). Based on evaluation of these specimens and disks, two alloys (AF2-1DA and Mar-M-432) were selected for scale-up evaluation. Using fabricating experience gained in the subscale turbine disk effort, test specimens and full scale turbine disks were formed from the selected alloys. These specimens and disks were then subjected to a rigorous test program to evaluate their physical properties and determine their suitability for use in advanced performance turbine engines. A major objective of the program was to develop processes which would yield alloy properties that would be repeatable in producing jet engine disks from the same powder metallurgy alloys. The feasibility of manufacturing full scale gas turbine engine disks by thermomechanical processing of pre-alloyed metal powders was demonstrated. AF2-1DA was shown to possess tensile and creep-rupture properties in excess of those of Astroloy, one of the highest temperature capability disk alloys now in production. It was determined that metallographic evaluation after post-HIP elevated temperature exposure should be used to verify the effectiveness of consolidation of hot isostatically pressed billets.

  19. Observing Planet Formation in Young Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Jang-Condell, Hannah; Kuchner, M. J.; Debes, J. H.

    2009-01-01

    Identification and observation of where and when gaps form in protoplanetary disks is vital for learning about the process of planet formation. We will present simulations of radiative transfer in gas-rich protoplanetary disks with embedded planets that predict and model observable signatures of planet formation. Depending on the mass of the planet, the perturbation may be a local dimple or an annular gap. We will demonstate that these features can already be detected in some nearby gas-rich disks. The appearance of disks with embedded planets varies with wavelength as it ranges from optical through infrared to radio because of optical depth effects. Shorter wavelengths reveal superficial surface features of disks, while longer wavelengths probe deeper in the disk. Confirmation of a planet-induced gap in a disk requires multi-wavelength observations. Imaging of the predicted features of planet formation in disks requires very high spatial resolution, and is currently most feasible in the optical and radio. However, data in the infrared is crucial for constraining the models. Deep gaps created by very massive planets may be detectable in SEDs. Confirmation of a planet-induced gap in a disk requires multi-wavelength observations.

  20. Stellar Multiplicity in the DEBRIS disk sample

    NASA Astrophysics Data System (ADS)

    Rodriguez, David R.; Duchene, Gaspard; Tom, Henry; Kennedy, Grant; Matthews, Brenda C.; Butner, Harold M.

    2015-01-01

    Circumstellar disks around young stars serve as the sites of planet formation. A common outcome of the star formation process is that of stellar binary systems. How does the presence of multiple stars affect the properties of disks, and thus of planet formation? To examine the frequency of disks around stellar binaries we carried out a multiplicity survey on stars in the DEBRIS sample. This sample consists of 451 stars of spectral types A-M observed with the Herschel Space Telescope. We have examined the stellar multiplicity of this sample by gathering information from the literature and performing an adaptive optics imaging survey at Lick Observatory. We identify 189 (42%) binary or multiple star systems.In our sample, we find that debris disks are less common around binaries than single stars, though the disk detection frequency is comparable among A stars regardless of multiplicity. Nevertheless, the period distribution of disk-bearing binaries is consistent with that of non-disk binaries and with comparison field samples. Although the frequency of disk-bearing binaries may be lower than in single star systems, the processes behind disk formation are comparable among both single and multiple-star populations.This work is supported in part by a Chile Fondecy grant #3130520.

  1. Disk's Spiral Arms Point to Possible Planets

    NASA Video Gallery

    Simulations of young stellar systems suggest that planets embedded in a circumstellar disk can produce many distinctive structures, including rings, gaps and spiral arms. This video compares comput...

  2. The physical and chemical evolution of protostellar disks. The growth of protostellar disks: Progress to date

    NASA Technical Reports Server (NTRS)

    Stahler, Steven W.

    1993-01-01

    This study constitutes one part of our multi-disciplinary approach to the evolution of planet-forming disks. The goal is to establish the disks' thermal and mechanical properties as they grow by the infall of their parent interstellar clouds. Thus far, significant advances toward establishing the evolving surface density of such disks was made.

  3. ON THE TRANSITIONAL DISK CLASS: LINKING OBSERVATIONS OF T TAURI STARS AND PHYSICAL DISK MODELS

    SciTech Connect

    Espaillat, C.; Andrews, S.; Qi, C.; Wilner, D.; Ingleby, L.; Calvet, N.; Hernandez, J.; Furlan, E.; D'Alessio, P.; Muzerolle, J. E-mail: sandrews@cfa.harvard.edu E-mail: dwilner@cfa.harvard.edu E-mail: ncalvet@umich.edu E-mail: Elise.Furlan@jpl.nasa.gov E-mail: muzerol@stsci.edu

    2012-03-10

    Two decades ago 'transitional disks' (TDs) described spectral energy distributions (SEDs) of T Tauri stars with small near-IR excesses, but significant mid- and far-IR excesses. Many inferred this indicated dust-free holes in disks possibly cleared by planets. Recently, this term has been applied disparately to objects whose Spitzer SEDs diverge from the expectations for a typical full disk (FD). Here, we use irradiated accretion disk models to fit the SEDs of 15 such disks in NGC 2068 and IC 348. One group has a 'dip' in infrared emission while the others' continuum emission decreases steadily at all wavelengths. We find that the former have an inner disk hole or gap at intermediate radii in the disk and we call these objects 'transitional disks' and 'pre-transitional disks' (PTDs), respectively. For the latter group, we can fit these SEDs with FD models and find that millimeter data are necessary to break the degeneracy between dust settling and disk mass. We suggest that the term 'transitional' only be applied to objects that display evidence for a radical change in the disk's radial structure. Using this definition, we find that TDs and PTDs tend to have lower mass accretion rates than FDs and that TDs have lower accretion rates than PTDs. These reduced accretion rates onto the star could be linked to forming planets. Future observations of TDs and PTDs will allow us to better quantify the signatures of planet formation in young disks.

  4. Nickel Base Superalloy Turbine Disk

    NASA Technical Reports Server (NTRS)

    Gabb, Timothy P. (Inventor); Gauda, John (Inventor); Telesman, Ignacy (Inventor); Kantzos, Pete T. (Inventor)

    2005-01-01

    A low solvus, high refractory alloy having unusually versatile processing mechanical property capabilities for advanced disks and rotors in gas turbine engines. The nickel base superalloy has a composition consisting essentially of, in weight percent, 3.0-4.0 N, 0.02-0.04 B, 0.02-0.05 C, 12.0-14.0 Cr, 19.0-22.0 Co, 2.0-3.5 Mo, greater than 1.0 to 2.1 Nb, 1.3 to 2.1 Ta,3.04.OTi,4.1 to 5.0 W, 0.03-0.06 Zr, and balance essentially Ni and incidental impurities. The superalloy combines ease of processing with high temperature capabilities to be suitable for use in various turbine engine disk, impeller, and shaft applications. The Co and Cr levels of the superalloy can provide low solvus temperature for high processing versatility. The W, Mo, Ta, and Nb refractory element levels of the superalloy can provide sustained strength, creep, and dwell crack growth resistance at high temperatures.

  5. A comprehensive study of proto-planetary disks around Herbig Ae stars using long-baseline infrared interferometry

    NASA Astrophysics Data System (ADS)

    Tannirkulam, Ajay-Kumar M.

    Planetary systems are born in circumstellar disks around young stellar objects (YSOs) and the disk is thought to play a major role in the evolution of planetary systems. A good understanding of disk structure and its time evolution is therefore essential in comprehending planet formation, planet migration and the diversity of planetary systems. In this thesis, I use high angular resolution observations and state-of-the-art radiative transfer modeling to probe circumstellar disk structure and validate current disk models. First, I discuss models and observations of the gas-dust transition region in YSOs. The dust component in circumstellar disks gets truncated at a finite radius from the central star, inside of which it is too hot for dust to survive. The truncated disk forms an "evaporation front" whose shape depends sensitively on dust properties. The possibility of using the front as a probe of the dust physics operating in circumstellar disks is explored. The Center for High Angular Resolution Astronomy (CHARA) near-infrared (near-IR) array is used to resolve out the evaporation front in the Herbig Ae stars MWC275 and AB Aur, and the presence of an additional near-IR opacity source within the "conventional" dust destruction radius is reported. Second, I describe comprehensive disk models that simultaneously explain the spectral energy distribution (from UV to milli-meter) and long-baseline interferometry (from near-IR to mm) of Herbig Ae stars. The models are constrained with a wide range of data drawn from the literature as well as new interferometric observations in the K-band with the CHARA array and in the mid-IR with the novel Keck Segment Tilting Experiment. I show that the mid-IR size of MWC275 relative to AB Aur is small, suggesting that dust grains in the outer disk of MWC275 are significantly more evolved/settled than the grains in the AB Aur disk. Using the Segment Tilting data, I also demonstrate that Herbig Ae/Be systems having a higher mid

  6. Disc configuration exact diagonalization studies of the phase diagram and edge states of the ν = 5 / 2 fractional quantum Hall state with Landau level mixing and finite well thickness

    NASA Astrophysics Data System (ADS)

    Tylan-Tyler, Anthony; Lyanda-Geller, Yuli

    2015-03-01

    The ν = 5 / 2 fractional quantum Hall effect is of experimental and theoretical interest as a possible manifestation of non-Abelian statistics. The nature of this state has yet to be fully determined. The leading candidates are the Moore-Read Pfaffian state and its particle-hole conjugate, the anti-Pfaffian. When effects which break particle-hole symmetry are not included, these states are degenerate. We carry out an exact diagonalization calculation in a disk of neutralizing charge configuration, which breaks this degeneracy, and include Landau level mixing interactions arising from a diagrammatic expansion of the Coulomb potential and the effects of finite thickness. The Pfaffian sector is shown to favor strong interactions with the neutralizing background and strong Landau level(LL) mixing, while the anti-Pfaffian state occurs at weak LL mixing and background interactions. We find that there is a phase transition from the anti-Pfaffian to the Pfaffian state through a series of compressible stripe states as LL mixing is turned on. Furthermore, LL mixing interactions lead to an increased quasihole size and can overcome the effects of edge reconstruction. When the effects of the finite thickness of the confining quantum well are included, we observe enhancement these properties. Research was supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Award DE-SC0010544.

  7. Automatic finite element generators

    NASA Technical Reports Server (NTRS)

    Wang, P. S.

    1984-01-01

    The design and implementation of a software system for generating finite elements and related computations are described. Exact symbolic computational techniques are employed to derive strain-displacement matrices and element stiffness matrices. Methods for dealing with the excessive growth of symbolic expressions are discussed. Automatic FORTRAN code generation is described with emphasis on improving the efficiency of the resultant code.

  8. Alignments Of Black Holes with Their Warped Accretion Disks and Episodic Lifetimes of Active Galactic Nuclei

    NASA Astrophysics Data System (ADS)

    Li, Yan-Rong; Wang, Jian-Min; Cheng, Cheng; Qiu, Jie

    2015-05-01

    Warped accretion disks have attracted intense attention because of their critical role in shaping the spin of supermassive massive black holes (SMBHs) through the Bardeen-Petterson effect, a general relativistic effect that leads to final alignments or anti-alignments between black holes and warped accretion disks. We study such alignment processes by explicitly taking into account the finite sizes of accretion disks and the episodic lifetimes of active galactic nuclei (AGNs) that delineate the duration of gas fueling onto accretion disks. We employ an approximate global model to simulate the evolution of accretion disks, allowing us to determine the gravitomagnetic torque that drives the alignments in a simple way. We then track down the evolutionary paths for mass and spin of black holes both in a single activity episode and over a series of episodes. Given with randomly and isotropically oriented gas fueling over episodes, we calculate the spin evolution with different episodic lifetimes and find that it is quite sensitive to the lifetimes. We therefore propose that the spin distribution of SMBHs can place constraints on the episodic lifetimes of AGNs and vice versa. The applications of our results on the observed spin distributions of SMBHs and the observed episodic lifetimes of AGNs are discussed, although both measurements at present are too ambiguous for us to draw a firm conclusion. Our prescription can be easily incorporated into semi-analytic models for black hole growth and spin evolution.

  9. Numerical Studies on Time-Varying Stiffness of Disk-Drum Type Rotor with Bolt Loosening

    NASA Astrophysics Data System (ADS)

    Qin, Zhaoye; Chu, Fulei

    2015-07-01

    Disk-drum type rotors are widely used in industry for their high stiffness and low weight properties. In disk-drum type rotors, the adjacent disks and drums are commonly connected by bolted joints. Those rotating joint interfaces are subjected to numerous combinations of loads during normal operation, where loosening of the connecting bolts might occur. The bolt loosening will change the local stiffness of the rotor, which in turn affect the rotor dynamics and even result in structural failures. In this paper, the local stiffness of a disk- drum rotor with bolt loosening is investigated numerically. A three-dimensional (3D) finite element (FE) model for the bolted disk-drum joint is established in ANSYS, where the bolt loosening is simulated by reducing the preloads of certain bolts, and removing those bolts as the limiting case. Simulations are performed on the FE model to evaluate the joint behaviour under static loads. Periodic variations of the joint deflections with respect to the rotation angle of the shaft are obtained, which implies the appearance of the time-varying local stiffness in the rotor system. The studies in this paper help accurate prediction of the rotor dynamics and early detection of bolt loosening.

  10. Enhanced actuation of nanocrystalline diamond microelectromechanical disk resonators with AlN layers

    NASA Astrophysics Data System (ADS)

    Yoshikawa, Taro; Reusch, Markus; Holc, Katarzyna; Iankov, Dimitre; Zuerbig, Verena; Zukauskaite, Agne; Nebel, Christoph E.; Ambacher, Oliver; Lebedev, Vadim

    2016-04-01

    A great potential of the use of aluminum nitride (AlN) to enhance the actuation of nanocrystalline diamond (NCD) microelectromechanical system disk resonators is revealed. A disk resonator with a unimorph (AlN/NCD) structure is fabricated by depositing a c-axis oriented AlN on a capacitive NCD disk resonator. The unimorph resonator is piezoelectrically actuated with flexural whispering gallery modes with a relatively large electrode gap spacing, i.e., the spacing which is greater than 1 μm, although this is not possible for the capacitive NCD disk resonator. This result is explained by a finite element method simulation where the piezoelectric actuation turns out to be more effective than the capacitive actuation when the electrode gap spacing is >0.8 μm. The simulation also shows that the electrode gap spacing required for the capacitive actuation to be more effective than the piezoelectric actuation exponentially decreases when the resonator dimension is scaled down for higher frequency operations. Our study indicates that the use of AlN is promising to decrease impedance levels of NCD disk resonators especially for their higher frequency operations.

  11. Lifetimes and Accretion Rates of Protoplanetary Disks

    NASA Astrophysics Data System (ADS)

    Li, Min; Xiao, Lin

    2016-03-01

    Protoplanetary disks originate in the collapse of molecular cloud cores. The formation and evolution of disks are influenced by the properties of molecular cloud cores. In this paper we investigate the dependence of disk lifetimes and accretion rates on cloud core properties. We find that the lifetime increases as the angular velocities and the mass of cloud cores increase and that the lifetime decreases as the core temperature increases. We have calculated the distribution of disk lifetimes and disk fractions with stellar age. Our calculations show that the lifetime is in the range of 1-15 Myr and that the typical lifetime is 1-3 Myr. There are a few disks with lifetimes greater than 10 Myr and ˜ 30% of the disks have lifetimes less than 1 Myr. We also fit the disk fraction by an exponential decay curve with characteristic time ˜3.7 Myr. Our results explain the observations of disk lifetimes. We also find that the accretion rate does not change significantly with ω and generally decreases with {T}{{cd}}. At the early evolution of the disks, the \\dot{M}{--}{M}* relation is about \\dot{M}\\propto {M}*1.2-2. Since the effects of the photoevaporation are weak at this stage, this relation is the consequence of the cloud core properties. At the late evolution of the disks, the \\dot{M}{--}{M}* relation is about \\dot{M}\\propto {M}*1.2-1.7. For low accretion rates at this stage, the \\dot{M}{--}{M}* relation results from the effects of X-ray photoevaporation. The calculated \\dot{M}{--}{M}* relations are consistent with the observations.

  12. Gene Therapy for Neurologic Manifestations of Mucopolysaccharidoses

    PubMed Central

    Wolf, Daniel A.; Banerjee, Sharbani; Hackett, Perry B.; Whitley, Chester B.; McIvor, R. Scott; Low, Walter C.

    2015-01-01

    Introduction Mucopolysaccharidoses are a family of lysosomal disorders caused by mutations in genes that encode enzymes involved in the catabolism of glycoaminoglycans. These mutations affect multiple organ systems and can be particularly deleterious to the nervous system. At the present time, enzyme replacement therapy and hematopoietic stem-cell therapy are used to treat patients with different forms of these disorders. However, to a great extent the nervous system is not adequately responsive to current therapeutic approaches. Areas Covered Recent advances in gene therapy show great promise for treating mucopolysaccharidoses. This article reviews the current state of the art for routes of delivery in developing genetic therapies for treating the neurologic manifestations of mucopolysaccharidoses. Expert Opinion Gene therapy for treating neurological manifestations of mucopolysaccharidoses can be achieved by intraventricular, intrathecal, intranasal, and systemic administration. The intraventricular route of administration appears to provide the most wide-spread distribution of gene therapy vectors to the brain. The intrathecal route of delivery results in predominant distribution to the caudal areas of the brain while the intranasal route of delivery results in good distribution to the rostral areas of brain. The systemic route of delivery via intravenous delivery can also achieve wide spread delivery to the CNS, however, the distribution to the brain is greatly dependent on the vector system. Intravenous delivery using lentiviral vectors appear to be less effective than adeno-associated viral (AAV) vectors. Moreover, some subtypes of AAV vectors are more effective than others in crossing the blood-brain-barrier. In summary, the recent advances in gene vector technology and routes of delivery to the CNS will facilitate the clinical translation of gene therapy for the treatment of the neurological manifestations of mucopolysaccharidoses. PMID:25510418

  13. A disk-type magneto-rheological fluid damper for rotor system vibration control

    NASA Astrophysics Data System (ADS)

    Zhu, Changsheng

    2005-05-01

    Based on the particular characteristic of a magneto-rheological (MR) fluid, i.e., a rapid, reversible and dramatic change in its rheological properties produced by the application of an external magnetic field, a simple disk-type MR fluid damper operating in shear flow mode is presented in this paper. The magnetic field of the disk-type MR fluid damper is analyzed by the finite element method in order to show if the design is reasonable. The effect of excitation current in the coil on the magnetic flux density in the axial gaps filled with the MR fluid is studied both theoretically and experimentally. Finally, the effectiveness of the disk-type MR fluid damper for attenuating the vibration of rotor systems and of a simple open-loop on-off control based on the feedback of rotational speed for controlling vibration of rotor systems are experimentally studied in a flexible rotor system. It is shown that the dynamic characteristics of the disk-type MR fluid damper can be easily controlled by a steady magnetic field produced by a simple electrical magnetic coil with a low DC current (less than 1 A) and that the disk-type MR fluid damper is very effective for attenuating and controlling the vibration of the rotor systems. It is possible to supply the optimum supporting damping for every vibration mode in the rotor system by using the disk-type MR damper, if the location of the disk-type MR fluid damper in the rotor is properly chosen.

  14. GLOBAL SIMULATIONS OF ACCRETION DISKS. I. CONVERGENCE AND COMPARISONS WITH LOCAL MODELS

    SciTech Connect

    Sorathia, Kareem A.; Reynolds, Christopher S.; Stone, James M.; Beckwith, Kris

    2012-04-20

    Grid-based magnetohydrodynamic (MHD) simulations have proven invaluable for the study of astrophysical accretion disks. However, the fact that angular momentum transport in disks is mediated by MHD turbulence (with structure down to very small scales) raises the concern that the properties of the modeled accretion disks are affected by the finite numerical resolution of the simulation. By implementing an orbital advection algorithm into the Athena code in cylindrical geometry, we have performed a set of global (but unstratified) Newtonian disk simulations extending up to resolutions previously unattained. We study the convergence of these models as a function of spatial resolution and initial magnetic field geometry. The usual viscosity parameter ({alpha}) or the ratio of thermal-to-magnetic pressure ({beta}) is found to be a poor diagnostic of convergence, whereas the average tilt angle of the magnetic field in the (r, {phi})-plane is a very good diagnostic of convergence. We suggest that this is related to the saturation of the MHD turbulence via parasitic modes of the magnetorotational instability. Even in the case of zero-net magnetic flux, we conclude that our highest resolution simulations (with 32 zones and 64 zones per vertical scale height) have achieved convergence. Our global simulations reach resolutions comparable to those used in local, shearing-box models of MHD disk turbulence. We find that the saturation predictors derived from local simulations correspond well to the instantaneous correlations between local flux and stress found in our global simulations. However, the conservation of magnetic flux implicit in local models is not realized in our global disks. Thus, the magnetic connectivity of an accretion disk represents physics that is truly global and cannot be captured in any ab initio local model.

  15. Manifestation of optical activity in different materials

    NASA Astrophysics Data System (ADS)

    Konstantinova, A. F.; Golovina, T. G.; Konstantinov, K. K.

    2014-07-01

    Various manifestations of optical activity (OA) in crystals and organic materials are considered. Examples of optically active enantiomorphic and nonenantiomorphic crystals of 18 symmetry classes are presented. The OA of enantiomorphic organic materials as components of living nature (amino acids, sugars, and proteins) is analyzed. Questions related to the origin of life on earth are considered. Examples of differences in the enantiomers of drugs are shown. The consequences of replacing conventional left-handed amino acids with additionally right-handed amino acids for living organisms are indicated.

  16. Ocular manifestations of infectious skin diseases.

    PubMed

    Sadowska-Przytocka, Anna; Czarnecka-Operacz, Magdalena; Jenerowicz, Dorota; Grzybowski, Andrzej

    2016-01-01

    Ocular complications of infectious skin diseases are a common occurrence. Managing the inflamed or infected eye in the emergency setting presents a diagnostic and therapeutic challenge to the emergency physician. Infectious agents may affect any part of the eye. Ocular findings may be the first sign of many infectious diseases, such as, for example, gonorrhea or chlamydia infection. Understanding the various forms of ocular involvement in these conditions is important, because untreated ophthalmic involvement can lead to severe vision loss. This review focuses on the significant ocular manifestations of the most common infectious diseases, including bacterial, viral, fungal, and parasitic infections, that both ophthalmologists and dermatologists may encounter. PMID:26903179

  17. Rhodococcus equi: clinical manifestations, virulence, and immunity.

    PubMed

    Giguère, S; Cohen, N D; Chaffin, M Keith; Hines, S A; Hondalus, M K; Prescott, J F; Slovis, N M

    2011-01-01

    Pneumonia is a major cause of disease and death in foals. Rhodococcus equi, a gram-positive facultative intracellular pathogen, is a common cause of pneumonia in foals. This article reviews the clinical manifestations of infection caused by R. equi in foals and summarizes current knowledge regarding mechanisms of virulence of, and immunity to, R. equi. A complementary consensus statement providing recommendations for the diagnosis, treatment, control, and prevention of infections caused by R. equi in foals can be found in the same issue of the Journal. PMID:22092609

  18. Cardiac Manifestation of Acute Lymphoblastic Leukemia.

    PubMed

    Werner, Rudolf A; Rudelius, Martina; Thurner, Annette; Higuchi, Takahiro; Lapa, Constantin

    2016-07-01

    Here, we report on a 38-year-old man with unclear right heart failure. Imaging with cardiac MRI and combined PET/CT with F-FDG revealed a hypermetabolic mass extending from the right ventricle to the atrium. In addition, intense glucose utilization throughout the bone marrow was noted. Biopsies of both bone marrow and cardiac mass were performed and revealed precursor B-cell acute lymphoblastic leukemia with gross leukemic infiltration of the myopericardium, a rare manifestation of acute lymphoblastic leukemia at initial diagnosis. PMID:27088389

  19. Manifestation of psoriasis in the oral cavity.

    PubMed

    Fatahzadeh, Mahnaz

    2016-03-01

    Despite the common prevalence of cutaneous psoriasis, the existence of manifestations in the oral cavity is subject to controversy. In this article, dermatologic psoriasis is reviewed, and a patient with generalized, symptomatic oral mucosal erythema resembling atrophic candidiasis synchronous with flare of chronic skin psoriasis is described. Diagnostic work up and therapeutic response supported that these mucosal findings were the oral counterpart of cutaneous disease. Dental providers should be familiar with the signs and symptoms of oral psoriasis, institute appropriate preventive measures, and provide palliation directed at symptomatic oral changes of psoriasis. PMID:26665263

  20. Skin manifestations of chronic kidney disease.

    PubMed

    Robles-Mendez, J C; Vazquez-Martinez, O; Ocampo-Candiani, J

    2015-10-01

    Skin manifestations associated with chronic kidney disease are very common. Most of these conditions present in the end stages and may affect the patient's quality of life. Knowledge of these entities can contribute to establishing an accurate diagnosis and prognosis. Severe renal pruritus is associated with increased mortality and a poor prognosis. Nail exploration can provide clues about albumin and urea levels. Nephrogenic systemic fibrosis is a preventable disease associated with gadolinium contrast. Comorbidities, such as diabetes mellitus and secondary hyperparathyroidism, can lead to acquired perforating dermatosis and calciphylaxis, respectively. Effective and innovative treatments are available for all of these conditions. PMID:26093993

  1. Reiki and changes in pattern manifestations.

    PubMed

    Ring, Marcia E

    2009-07-01

    The purposes of this qualitative research study were to describe the changes in pattern manifestations that individuals experienced associated with receiving Reiki, and to present the theoretical understanding of these changes. The unitary field pattern portrait research method was utilized because it was ontologically, epistemologically, and methodologically consistent with the science of unitary human beings. Reiki was found to be associated with changes in awareness from dissonance and turbulence to harmony and well-being by helping individuals knowingly participate in actualizing their own capacities for healing. Reiki was found to be an appropriate voluntary mutual patterning nursing modality. PMID:19567731

  2. Systemic Sclerosis with Multiple Pulmonary Manifestations

    PubMed Central

    Suresh, Parinita; Reddy, Venkata Siva Prasad; Sharma, Tarun; Salim, Nabil Ahmed

    2016-01-01

    Systemic sclerosis (SSc) is a chronic autoimmune multisystem disorder characterized by endothelial dysfunction and fibroblast dysfunction, which results in progressive fibrosis of the skin and internal organs more frequently the lungs and gastro intestinal tract. Pulmonary involvement is common in the course of SSc, with Interstitial Lung Disease (ILD) and Pulmonary Arterial Hypertension (PAH) being the leading causes of death. Here we report, case of an elderly female patient presenting with Diffuse SSc with multiple uncommon pulmonary manifestations like ILD with Usual Interstitial Pneumonia (UIP) pattern (usually less common), PAH and right sided pleural effusion. PMID:27504339

  3. Nonlinear, finite deformation, finite element analysis

    NASA Astrophysics Data System (ADS)

    Nguyen, Nhung; Waas, Anthony M.

    2016-06-01

    The roles of the consistent Jacobian matrix and the material tangent moduli, which are used in nonlinear incremental finite deformation mechanics problems solved using the finite element method, are emphasized in this paper, and demonstrated using the commercial software ABAQUS standard. In doing so, the necessity for correctly employing user material subroutines to solve nonlinear problems involving large deformation and/or large rotation is clarified. Starting with the rate form of the principle of virtual work, the derivations of the material tangent moduli, the consistent Jacobian matrix, the stress/strain measures, and the objective stress rates are discussed and clarified. The difference between the consistent Jacobian matrix (which, in the ABAQUS UMAT user material subroutine is referred to as DDSDDE) and the material tangent moduli ( C e ) needed for the stress update is pointed out and emphasized in this paper. While the former is derived based on the Jaumann rate of the Kirchhoff stress, the latter is derived using the Jaumann rate of the Cauchy stress. Understanding the difference between these two objective stress rates is crucial for correctly implementing a constitutive model, especially a rate form constitutive relation, and for ensuring fast convergence. Specifically, the implementation requires the stresses to be updated correctly. For this, the strains must be computed directly from the deformation gradient and corresponding strain measure (for a total form model). Alternatively, the material tangent moduli derived from the corresponding Jaumann rate of the Cauchy stress of the constitutive relation (for a rate form model) should be used. Given that this requirement is satisfied, the consistent Jacobian matrix only influences the rate of convergence. Its derivation should be based on the Jaumann rate of the Kirchhoff stress to ensure fast convergence; however, the use of a different objective stress rate may also be possible. The error associated

  4. Grinding Glass Disks On A Belt Sander

    NASA Technical Reports Server (NTRS)

    Lyons, James J., III

    1995-01-01

    Small machine attached to table-top belt sander makes possible to use belt sander to grind glass disk quickly to specified diameter within tolerance of about plus or minus 0.002 in. Intended to be used in place of production-shop glass grinder. Held on driveshaft by vacuum, glass disk rotated while periphery ground by continuous sanding belt.

  5. SLIM DISKS AROUND KERR BLACK HOLES REVISITED

    SciTech Connect

    Sadowski, Aleksander

    2009-08-01

    We investigate stationary slim accretion disks around Kerr black holes. We construct a new numerical method based on the relaxation technique. We systematically cover the whole parameter space relevant to stellar mass X-ray binaries. We also notice some non-monotonic features in the disk structure, overlooked in previous studies.

  6. Fabrication of large ceramic electrolyte disks

    NASA Technical Reports Server (NTRS)

    Ring, S. A.

    1972-01-01

    Process for sintering compressed ceramic powders produces large ceramic disks for use as electrolytes in high-temperature electrolytic cells. Thin, strain-free uniformly dense disks as large as 30 cm squared have been fabricated by slicing ceramic slugs produced by this technique.

  7. Protoplanetary Disk Evolution: Singles vs. Binaries

    NASA Astrophysics Data System (ADS)

    Daemgen, Sebastian; Jayawardhana, Ray; Petr-Gotzens, Monika G.; Meyer, Elliot

    2016-01-01

    Based on a large number of observations carried out in the last decade it appears that the fraction of stars with protoplanetary disks declines steadily between ~1 Myr and ~10 Myr. We do, however, know that the multiplicity fraction of star-forming regions can be as high as >50% and that multiples have reduced disk lifetimes on average. As a consequence, the observed roughly exponential disk decay can be fully attributed neither to single nor binary stars and its functional form may need revision. Observational evidence for a non-exponential decay has been provided by Kraus et al. (2012), who statistically correct previous disk frequency measurements for the presence of binaries and find agreement with models that feature a constantly high disk fraction up to ~3 Myr, followed by a rapid (<~2 Myr) decline. We present results from our high angular resolution observational program to study the fraction of protoplanetary disks of single and binary stars separately. We find that disk evolution timescales of stars bound in close binaries (<100 AU) are significantly reduced compared to wider binaries. The frequencies of accretors among single stars and wide binaries appear indistinguishable, and are found to be lower than predicted from planet forming disk models governed by viscous evolution and photoevaporation.

  8. Magnetohydrodynamic simulations of outflows from accretion disks

    NASA Technical Reports Server (NTRS)

    Ustyugova, G. V.; Koldoba, A. V.; Romanova, M. M.; Chechetkin, V. M.; Lovelace, R. V. E.

    1995-01-01

    Magnetohydrodynamic simulations have been made of the formation of outflows from a Keplerian disk threaded by a magnetic field. The disk is treated as a boundary condition, where matter is ejected with Keplerian azimuthal speed and poloidal speed less than the slow magnetosonic velocity, and where boundary conditions on the magnetic field correspond to a highly conducting disk. Initially, the space above the disk, the corona, is filled with high specific entropy plasma in thermal equilibrium in the gravitational potential of the central object. The initial magnetic field is poloidal and is represented by a superposition of monopoles located below the plane of the disk. The rotation of the disk twists the initial poloidal magnetic field, and this twist propagates into the corona pushing and collimating matter into jetlike outflow in a cylindrical region. Matter outflowing from the disk flows and accelerates in the z-direction owing to both the magnetic and pressure gradient forces. The flow accelerates through the slow magnetosonic and Alfven surfaces and at larger distances through the fast magnetosonic surface. The flow velocity of the jet is approximately parallel to the z-axis, and the collimation results from the pinching force of the toroidal magnetic field. For a nonrotating disk no collimation is observed.

  9. Dispersal of Disks Around Young Stars

    NASA Technical Reports Server (NTRS)

    Hollenbach, David; DeVincenzi, D. (Technical Monitor)

    2002-01-01

    We review the evidence pertaining to the lifetimes of planet-forming disks and discuss possible disk dispersal mechanisms: 1) viscous accretion of material onto the central source; 2) close stellar encounters; 3) stellar winds; and 4) photoevaporation by ultraviolet radiation. We focus on 3) and 4) and describe the quasi-steady state appearance and the overall evolution of disks under the influence of winds and radiation from the central star and of radiation from external OB stars. Viscous accretion likely dominates disk dispersal in the inner disk (r approx. or less than 10 AU), while photoevaporation is the principal process of disk dispersal outside of r approx. or greater than 10 AU for low mass stars. Disk dispersal timescales are compared and discussed in relation to theoretical estimates for planet formation timescales. Photoevaporation may explain the large differences in the hydrogen content of the giant planets in the solar system. The commonly held belief that our early sun's stellar wind dispersed he solar nebula is called into question. Finally, we model the small bright objects ('proplyds') observed in the Orion Nebula as disks around young, low mass stars which are externally illuminated by the UV (ultraviolet) photons from the nearby massive star Theta(1)C.

  10. Dispersal of Disks Around Young Stars

    NASA Technical Reports Server (NTRS)

    Hollenbach, David

    2001-01-01

    We review the evidence pertaining to the lifetimes of planet-forming disks and discuss possible disk dispersal mechanisms: 1) viscous accretion of material onto the central source, 2) close stellar encounters, 3) stellar winds, and 4) photoevaporation by ultraviolet radiation. We focus on 3) and 4) and describe the quasi-steady state appearance and the overall evolution of disks under the influence of winds and radiation from the central star and of radiation from external OB stars. Viscous accretion likely dominates disk dispersal in the inner disk (r < or approx. equals 10 AU), while photoevaporation is the principal process of disk dispersal outside of r > or approx. equals 10 AU for low mass stars. Disk dispersal timescales are compared and discussed in relation to theoretical estimates for planet formation timescales. Photoevaporation may explain the large differences in the hydrogen content of the giant planets in the solar system. The commonly held belief that our early sun's stellar wind dispersed the solar nebula is called into question. Finally, we model the small bright objects ("proplyds") observed in the Orion Nebula as disks around young, low mass stars which are externally illuminated by the UV photons from the nearby massive star Theta(sup 1)C.

  11. Attention Novices: Friendly Intro to Shiny Disks.

    ERIC Educational Resources Information Center

    Bardes, D'Ellen

    1986-01-01

    Provides an overview of how optical storage technologies--videodisk, Write-Once disks, and CD-ROM CD-I disks are built into and controlled via DEC, Apple, Atari, Amiga, and IBM PC compatible microcomputers. Several available products are noted and a list of producers is included. (EM)

  12. Recent development of disk lasers at TRUMPF

    NASA Astrophysics Data System (ADS)

    Schad, Sven-Silvius; Gottwald, Tina; Kuhn, Vincent; Ackermann, Matthias; Bauer, Dominik; Scharun, Michael; Killi, Alexander

    2016-03-01

    The disk laser is one of the most important laser concepts for today's industrial laser market. Offering high brilliance at low cost, high optical efficiency and great application flexibility the disk laser paved the way for many industrial laser applications. Over the past years power and brightness increased and the disk laser turned out to be a very versatile laser source, not only for welding but also for cutting. Both, the quality and speed of cutting are superior to CO2-based lasers for a vast majority of metals, and, most important, in a broad thickness range. In addition, due to the insensitivity against back reflections the disk laser is well suited for cutting highly reflective metal such as brass or copper. These advantages facilitate versatile cutting machines and explain the high and growing demand for disk lasers for applications besides welding applications that can be observed today. From a today's perspective the disk principle has not reached any fundamental limits regarding output power per disk or beam quality, and offers numerous advantages over other high power resonator concepts, especially over fiber lasers or direct diode lasers. This paper will give insight in the latest progress in kilowatt class cw disk laser technology at TRUMPF and will discuss recent power scaling results as well.

  13. The Transitional Disks Associated With Herbig Stars

    NASA Technical Reports Server (NTRS)

    Grady, C.; Fukagawa, M.; Maruta, Y.; Ohta, Y.; Wisniewski, J.; Lomax, J.; Hashimoto, J.; Currie, T.; Okamoto, Y.; Momose, M.; McElwain, M.

    2015-01-01

    As part of the Strategic Exploration of Exoplanets and Disks with Subaru YSO survey, we have surveyed a number of Herbig B-F stars mainly at H-band using Polarimetric Differential Imaging + Angular differential imaging. Historically, Herbig stars have been sorted by the shape of the IR SEDs into those which can be fit by power laws over 1-200 micrometers (Meeus et al. 2001, group II), and those which can be interpreted as a power law + a blackbody component (Meeus group I) or as transitional or pre-transitional disks (Maaskant et al. 2013). Meeus group II disks, when imaged with HiCIAO show featureless disks with depolarization along the projection of the disk semi-minor axis (Kusakabe et al. 2012). This is what we had expected to see for the Meeus group I disks, except for the addition of wide gaps or central cavities. Instead we find wild diversity, suggesting that transitional disks are highly perturbed compared to Meeus group II disks. To date, similar structure continues to be observed as higher Strehl ratio imagery becomes available.

  14. A Primer on Unifying Debris Disk Morphologies

    NASA Astrophysics Data System (ADS)

    Lee, Eve J.; Chiang, Eugene

    2016-08-01

    A “minimum model” for debris disks consists of a narrow ring of parent bodies, secularly forced by a single planet on a possibly eccentric orbit, colliding to produce dust grains that are perturbed by stellar radiation pressure. We demonstrate how this minimum model can reproduce a wide variety of disk morphologies imaged in scattered starlight. Five broad categories of disk shape can be captured: “rings,” “needles,” “ships-and-wakes,” “bars,” and “moths (a.k.a. fans),” depending on the viewing geometry. Moths can also sport “double wings.” We explain the origin of morphological features from first principles, exploring the dependence on planet eccentricity, disk inclination dispersion, and the parent body orbital phases at which dust grains are born. A key determinant in disk appearance is the degree to which dust grain orbits are apsidally aligned. Our study of a simple steady-state (secularly relaxed) disk should serve as a reference for more detailed models tailored to individual systems. We use the intuition gained from our guidebook of disk morphologies to interpret, informally, the images of a number of real-world debris disks. These interpretations suggest that the farthest reaches of planetary systems are perturbed by eccentric planets, possibly just a few Earth masses each.

  15. Cutaneous and ocular manifestations of neurocutaneous syndromes.

    PubMed

    Chernoff, Karen A; Schaffer, Julie V

    2016-01-01

    Neurocutaneous syndromes are a heterogeneous group of congenital and hereditary disorders with manifestations in the skin and the nervous system, usually together with ocular features that represent diagnostic clues and potential sources of morbidity. Dermatologists and ophthalmologists often need to work together in identifying and managing patients with these conditions; herein, we focus on classic and under-recognized neurocutaneous syndromes. We begin with autosomal dominant genodermatoses characterized by hamartomas and tumors in the skin, eyes, and central nervous system: neurofibromatosis type 1, tuberous sclerosis complex, and PTEN hamartoma-tumor syndrome. This is followed by a discussion of two mosaic disorders, Sturge-Weber syndrome and neurocutaneous melanocytosis. In addition to providing an update on clinical presentations and evaluation of patients with these conditions, we review recent insights into their pathogenesis, drawing attention to relationships among the diseases on a molecular level and implications regarding treatment. We also highlight the major features of other neurocutaneous syndromes that have ocular findings plus pigmentary, vascular, hyperkeratotic, adnexal, connective tissue, photosensitive, and inflammatory manifestations in the skin. PMID:26903185

  16. Canine MPV17 truncation without clinical manifestations

    PubMed Central

    Hänninen, Reetta L.; Ahonen, Saija; Màrquez, Merce; Myöhänen, Maarit J.; Hytönen, Marjo K.; Lohi, Hannes

    2015-01-01

    ABSTRACT Mitochondrial DNA depletion syndromes (MDS) are often serious autosomal recessively inherited disorders characterized by tissue-specific mtDNA copy number reduction. Many genes, including MPV17, are associated with the hepatocerebral form of MDS. MPV17 encodes for a mitochondrial inner membrane protein with a poorly characterized function. Several MPV17 mutations have been reported in association with a heterogeneous group of early-onset manifestations, including liver disease and neurological problems. Mpv17-deficient mice present renal and hearing defects. We describe here a MPV17 truncation mutation in dogs. We found a 1-bp insertion in exon 4 of the MPV17 gene, resulting in a frameshift and early truncation of the encoded protein. The mutation halves MPV17 expression in the lymphocytes of the homozygous dogs and the truncated protein is not translated in transfected cells. The insertion mutation is recurrent and exists in many unrelated breeds, although is highly enriched in the Boxer breed. Unexpectedly, despite the truncation of MPV17, we could not find any common phenotypes in the genetically affected dogs. The lack of observable phenotype could be due to a late onset, mild symptoms or potential tissue-specific compensatory mechanisms. This study suggests species-specific differences in the manifestation of the MPV17 defects and establishes a novel large animal model to further study MPV17 function and role in mitochondrial biology. PMID:26353863

  17. Hematologic manifestations of Helicobacter pylori infection

    PubMed Central

    Campuzano-Maya, Germán

    2014-01-01

    Helicobacter pylori (H. pylori) is the most common infection in humans, with a marked disparity between developed and developing countries. Although H. pylori infections are asymptomatic in most infected individuals, they are intimately related to malignant gastric conditions such as gastric cancer and gastric mucosa-associated lymphoid tissue (MALT) lymphoma and to benign diseases such as gastritis and duodenal and gastric peptic ulcers. Since it was learned that bacteria could colonize the gastric mucosa, there have been reports in the medical literature of over 50 extragastric manifestations involving a variety medical areas of specialization. These areas include cardiology, dermatology, endocrinology, gynecology and obstetrics, hematology, pneumology, odontology, ophthalmology, otorhinolaryngology and pediatrics, and they encompass conditions with a range of clear evidence between the H. pylori infection and development of the disease. This literature review covers extragastric manifestations of H. pylori infection in the hematology field. It focuses on conditions that are included in international consensus and management guides for H. pylori infection, specifically iron deficiency, vitamin B12 (cobalamin) deficiency, immune thrombocytopenia, and MALT lymphoma. In addition, there is discussion of other conditions that are not included in international consensus and management guides on H. pylori, including auto-immune neutropenia, antiphospholipid syndrome, plasma cell dyscrasias, and other hematologic diseases. PMID:25278680

  18. Pulmonary manifestations of gastroesophageal reflux disease

    PubMed Central

    Gaude, Gajanan S.

    2009-01-01

    Gastroesophageal reflux disease (GERD) may cause, trigger or exacerbate many pulmonary diseases. The physiological link between GERD and pulmonary disease has been extensively studied in chronic cough and asthma. A primary care physician often encounters patients with extra esophageal manifestations of GERD in the absence of heartburn. Patients may present with symptoms involving the pulmonary system; noncardiac chest pain; and ear, nose and throat disorders. Local irritation in the esophagus can cause symptoms that vary from indigestion, like chest discomfort and abdominal pain, to coughing and wheezing. If the gastric acid reaches the back of the throat, it may cause a bitter taste in the mouth and/or aspiration of the gastric acid into the lungs. The acid can cause throat irritation, postnasal drip and hoarseness, as well as recurrent cough, chest congestion and lung inflammation leading to asthma and/or bronchitis/ pneumonia. This clinical review examines the potential pathophysiological mechanisms of pulmonary manifestations of GERD. It also reviews relevant clinical information concerning GERD-related chronic cough and asthma. Finally, a potential management strategy for GERD in pulmonary patients is discussed. PMID:19641641

  19. CANDLE Syndrome: orodfacial manifestations and dental implications.

    PubMed

    Roberts, T; Stephen, L; Scott, C; di Pasquale, T; Naser-Eldin, A; Chetty, M; Shaik, S; Lewandowski, L; Beighton, P

    2015-01-01

    A South African girl with CANDLE Syndrome is reported with emphasis on the orodental features and dental management. Clinical manifestations included short stature, wasting of the soft tissue of the arms and legs, erythematous skin eruptions and a prominent abdomen due to hepatosplenomegaly. Generalized microdontia, confirmed by tooth measurement and osteopenia of her jaws, confirmed by digitalized radiography, were previously undescribed syndromic components. Intellectual impairment posed problems during dental intervention. The carious dental lesions and poor oral hygiene were treated conservatively under local anaesthetic. Prophylactic antibiotics were administered an hour before all procedures.Due to the nature of her general condition, invasive dental procedures were minimal. Regular follow-ups were scheduled at six monthly intervals. During this period, her overall oral health status had improved markedly.The CANDLE syndrome is a rare condition with grave complications including immunosuppression and diabetes mellitus. As with many genetic disorders, the dental manifestations are often overshadowed by other more conspicuous and complex syndromic features. Recognition of both the clinical and oral changes that occur in the CANDLE syndrome facilitates accurate diagnosis and appropriate dental management of this potentially lethal condition. PMID:26711936

  20. Periodontal manifestations of von Recklinghausen neuro fibromatosis.

    PubMed

    Shetty, Bhavya; Umesh, Y; Kranti, K; Seshan, Hema

    2013-03-01

    Neurofibroma is an uncommon benign tumor of the oral cavity derived from the cells that constitute the nerve sheath neurofibromatosis type 1 (NF1), also known as von Recklinghausen's disease, is the most common type of neurofibromatosis and accounts for about 90% of all cases. It is one of the most frequent human genetic diseases, with the prevalence of one case in 3,000 births. Neurofibroma is seen either as a solitary lesion or as part of the generalized syndrome of neurofibromatosis. The solitary form does not differ from the disseminated form or the multiple form of the disease, except that systemic and hereditary factors present in the disseminated form are absent in the solitary type. Oral cavity involvement by a solitary and peripheral plexiform neurofibroma in patients with no other signs of neurofibromatosis is uncommon. The expressivity of NF1 is extremely variable, with manifestations ranging from mild lesions to several complications and functional impairment. Oral manifestations can be found in almost 72% of NF1 patients. This is a case report of a 40-year-old lady with a history of multiple faint rounded densities in the skin, chest pain occasionally since 8 months and breathlessness since 1 year and swelling of the right side of the angle of the mandible with limited mouth opening. PMID:23869137

  1. Pulmonary pyoderma gangrenosum without cutaneous manifestations.

    PubMed

    Sakata, Kenneth Kazuto; Penupolu, Sudheer; Colby, Thomas Vail; Gotway, Michael Bruce; Wesselius, Lewis Jon

    2016-07-01

    Pyoderma gangrenosum is a chronic sterile skin disorder that is frequently seen in association with systemic disorders such as inflammatory bowel disease. Extracutaneous pyoderma gangrenosum is rare and most commonly occurs in the lungs. It is particularly unusual for extracutaneous pyoderma gangrenosum to manifest prior to skin findings and without an associated systemic disorder. A 19-year-old white man presented with shortness of breath and a productive cough. His skin exam was normal. Unenhanced chest computed tomography showed peripheral consolidations, areas of cavitation, nodules and bilateral pleural effusions. A bronchoalveolar lavage and an autoimmune panel were unremarkable. Right lung wedge biopsies via thoracostomy was performed and showed pulmonary pyoderma gangrenosum. He was treated with corticosteroids and has returned back to his baseline. This is the first case of pulmonary pyoderma gangrenosum without any associated underlying systemic disorder and without any cutaneous manifestations to date. Serial follow-ups are necessary to assess for the development of an associated systemic disorder or skin lesions. PMID:25354722

  2. Hepatic manifestations in juvenile systemic lupus erythematosus.

    PubMed

    El-Shabrawi, Mortada H; Farrag, Mona I

    2014-01-01

    Juvenile systemic lupus erythematosus (JSLE) is a chronic autoimmune disease characterized by multisystem involvement and diverse clinical and serological manifestations. Clinically significant hepatic disease is generally regarded as unusual in JSLE, but many studies have showed that hepatic disease may be more common in SLE than was usually thought. Hepatic disease does not cause significant morbidity and mortality, but subclinical liver involvement is common. One of the hepatic disorders associated with JSLE is autoimmune hepatitis (AIH). The precise etiology of AIH and JSLE remains unknown, however both AIH and JSLE are associated with antinuclear antibody (ANA) and multisystem disease manifestations. A shared immunologic response and genetic predisposition were suggested. Recently, new approaches for treatment of SLE and recent patents that could develop into novel therapeutic agents in clinical management of SLE have been proposed. An array of promising new therapies is currently emerging or being developed including B-cell depletion therapies, agents targeting B-cell survival factors, blockade of T-cell co-stimulation and present review, we will also report the case of a 12-year old girl who developed JSLE four years after her preliminary diagnosis with AIH. PMID:24383439

  3. Classifying functional manifestations of ectodermal dysplasias.

    PubMed

    Simeonsson, Rune J

    2009-09-01

    Ectodermal dysplasias (ED) encompass more than 200 conditions involving some combination of disorders of hair, nails, teeth, and sweat glands. The incidence of ED is relatively rare affecting about 7 of 10,000 births [Itin and Fistarol (2004)]. Individuals manifesting ED present with a wide range of disorders involving hair, nails, teeth, and sweat glands and in many cases other characteristics as well. The complex nature of the disorder has presented challenges for clinical practice and required the involvement of multiple approaches and disciplines. It has also resulted in significant research initiatives on cause and symptomatology. A significant challenge has been the search for comprehensive documentation of the varied and complex manifestations associated with ED. Existing classification systems of ED have focused on physiological and structural dimensions. Classification approaches with a broader focus including characteristics of functioning in persons with ED could facilitate clinical work and research initiatives. In this context, the potential utility of available classifications that address functioning and disability would be appropriate to consider in the search for a consensus classification of ED. To that end, the purpose of this article is to (a) review the status of classification of ED, (b) provide a brief overview of the International Classification of Functioning, Disability and Health-Children and Youth, ICF-CY [World Health Organization (2007); International Classification of Functioning, Disability and Health-Children and Youth. Geneva: WHO.], and (c) identify possible contributions of the ICF-CY to classification of ED's. PMID:19681156

  4. Citing geospatial feature inventories with XML manifests

    NASA Astrophysics Data System (ADS)

    Bose, R.; McGarva, G.

    2006-12-01

    Today published scientific papers include a growing number of citations for online information sources that either complement or replace printed journals and books. We anticipate this same trend for cartographic citations used in the geosciences, following advances in web mapping and geographic feature-based services. Instead of using traditional libraries to resolve citations for print material, the geospatial citation life cycle will include requesting inventories of objects or geographic features from distributed geospatial data repositories. Using a case study from the UK Ordnance Survey MasterMap database, which is illustrative of geographic object-based products in general, we propose citing inventories of geographic objects using XML feature manifests. These manifests: (1) serve as a portable listing of sets of versioned features; (2) could be used as citations within the identification portion of an international geospatial metadata standard; (3) could be incorporated into geospatial data transfer formats such as GML; but (4) can be resolved only with comprehensive, curated repositories of current and historic data. This work has implications for any researcher who foresees the need to make or resolve references to online geospatial databases.

  5. Sinking Satellites and Tilting Disk Galaxies

    NASA Astrophysics Data System (ADS)

    Huang, Siqin

    I perform fully self-consistent disk+halo+satellite N-body simulations to investigate the dynamical interaction between a disk galaxy and an infalling satellite. In particular, I study the following three different dynamical responses of the disk to the infalling satellite: tilting, warping, and thickening, as well as the dynamical effects of the parent galaxy on the infalling satellite: orbital decay and tidal disruption. The model in this thesis is characterized with two cosmologically significant improvements. First, the satellite starts at a distance more than three times of the radius of the optical disk. This ensures a realistic interaction among the satellite, the disk, and the halo in the course of the satellite infall. Secondly, evolution of the structure and velocity ellipsoid of the disk due to internal heating is allowed. I study the commonly arising case of satellites having density profiles comparable to that of the parent galaxy in contrast to that of compact satellites considered in previous work. I find that a disk is mainly tilted rather than heated by infalling satellites. Satellites of 10%, 20%, and 30% of the disk mass tilt the disk by angles of (2.9 ± 0.3)o,/ (6.3 ± 0.1)o, and (10.6 ± 0.2)o, respectively. However, only 3.4%, 6.9%, and 11.1% of the orbital angular momentum is transferred to the parent galaxy. The kinetic energy associated with the vertical motion in the initial coordinate frame of the disk is increased by (6 ± 3)%, (26 ± 3)%, and (51 ± 5)%, respectively, whereas the corresponding thermal energy associated with the vertical random motion in the tilted coordinate frame is only increased by (4 ± 3)%, (6 ± 2)%, and (10 ± 2)%, respectively. I find that satellites are mainly accreted onto the parent halo. Satellites having up to 20% of the disk mass produce no observable thickening, whereas a satellite with 30% of the disk mass produces little observable thickening inside the half-mass radius of the disk but significant

  6. BACKPRESSURE TESTING OF ROTARY MICROFILTER DISKS

    SciTech Connect

    Fowley, M.; Herman, D.

    2011-04-14

    The Savannah River National Laboratory (SRNL), under the Department of Energy (DOE) Office of Environmental Management (EM), is modifying and testing the SpinTek{trademark} rotary microfilter (RMF) for radioactive filtration service in the Department of Energy (DOE) complex. The RMF has been shown to improve filtration throughput when compared to other conventional methods such as cross-flow filtration. A concern with the RMF was that backpressure, or reverse flow through the disk, would damage the filter membranes. Reverse flow might happen as a result of an inadvertent valve alignment during flushing. Testing was completed in the Engineering Development Laboratory (EDL) located in SRNL to study the physical effects of backpressure as well as to determine the maximum allowable back-pressure for RMF disks. The RMF disks tested at the EDL were manufactured by SpinTek{trademark} Filtration and used a Pall Corporation PMM050 filter membrane (0.5 micron nominal pore size) made from 316L stainless steel. Early versions of the RMF disks were made from synthetic materials that were incompatible with caustic solutions and radioactive service as well as being susceptible to delaminating when subjected to backpressure. Figure 1-1 shows the essential components of the RMF; 3 rotating disks and 3 stationary turbulence promoters (or shear elements) are shown. Figure 1-2 show the assembly view of a 25 disk RMF proposed for use at the Savannah River Site (SRS) and at the Hanford Facility. The purpose of the testing discussed in this report was to determine the allowable backpressure for RMF disks as well as study the physical effects of backpressure on RMF disks made with the Pall PMM050 membrane. This was accomplished by pressurizing the disks in the reverse flow direction (backpressure) until the test limit was reached or until membrane failure occurred. Backpressure was applied to the disks with air while submerged in deionized (DI) water. This method provided a visual

  7. Adler-Bardeen theorem and manifest anomaly cancellation to all orders in gauge theories

    NASA Astrophysics Data System (ADS)

    Anselmi, Damiano

    2014-10-01

    We reconsider the Adler-Bardeen theorem for the cancellation of gauge anomalies to all orders, when they vanish at one loop. Using the Batalin-Vilkovisky formalism and combining the dimensional-regularization technique with the higher-derivative gauge invariant regularization, we prove the theorem in the most general perturbatively unitary renormalizable gauge theories coupled to matter in four dimensions, and identify the subtraction scheme where anomaly cancellation to all orders is manifest, namely no subtractions of finite local counterterms are required from two loops onwards. Our approach is based on an order-by-order analysis of renormalization, and, differently from most derivations existing in the literature, does not make use of arguments based on the properties of the renormalization group. As a consequence, the proof we give also applies to conformal field theories and finite theories.

  8. 40 CFR 263.25 - Electronic manifest signatures.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 40 Protection of Environment 26 2014-07-01 2014-07-01 false Electronic manifest signatures. 263.25 Section 263.25 Protection of Environment ENVIRONMENTAL PROTECTION AGENCY (CONTINUED) SOLID WASTES... Recordkeeping § 263.25 Electronic manifest signatures. (a) Electronic manifest signatures shall meet...

  9. 49 CFR 172.205 - Hazardous waste manifest.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ...) hazardous waste manifest (manifest) is prepared in accordance with 40 CFR 262.20 and is signed, carried, and... in accordance with 40 CFR 263.22. (5) Before accepting hazardous waste from a rail transporter, a non.... (h) A hazardous waste manifest required by 40 CFR part 262, containing all of the...

  10. 49 CFR 172.205 - Hazardous waste manifest.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ...) hazardous waste manifest (manifest) is prepared in accordance with 40 CFR 262.20 and is signed, carried, and... in accordance with 40 CFR 263.22. (5) Before accepting hazardous waste from a rail transporter, a non.... (h) A hazardous waste manifest required by 40 CFR part 262, containing all of the...

  11. 49 CFR 172.205 - Hazardous waste manifest.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ...) hazardous waste manifest (manifest) is prepared in accordance with 40 CFR 262.20 and is signed, carried, and... in accordance with 40 CFR 263.22. (5) Before accepting hazardous waste from a rail transporter, a non.... (h) A hazardous waste manifest required by 40 CFR part 262, containing all of the...

  12. 49 CFR 172.205 - Hazardous waste manifest.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ...) hazardous waste manifest (manifest) is prepared in accordance with 40 CFR 262.20 and is signed, carried, and... in accordance with 40 CFR 263.22. (5) Before accepting hazardous waste from a rail transporter, a non.... (h) A hazardous waste manifest required by 40 CFR part 262, containing all of the...

  13. 49 CFR 172.205 - Hazardous waste manifest.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ...) hazardous waste manifest (manifest) is prepared in accordance with 40 CFR 262.20 and is signed, carried, and... in accordance with 40 CFR 263.22. (5) Before accepting hazardous waste from a rail transporter, a non.... (h) A hazardous waste manifest required by 40 CFR part 262, containing all of the...

  14. 19 CFR 122.48 - Air cargo manifest.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 19 Customs Duties 1 2013-04-01 2013-04-01 false Air cargo manifest. 122.48 Section 122.48 Customs... AIR COMMERCE REGULATIONS Aircraft Entry and Entry Documents; Electronic Manifest Requirements for..., and Overflying the United States § 122.48 Air cargo manifest. (a) When required. Except as provided...

  15. 19 CFR 122.48 - Air cargo manifest.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 19 Customs Duties 1 2011-04-01 2011-04-01 false Air cargo manifest. 122.48 Section 122.48 Customs... AIR COMMERCE REGULATIONS Aircraft Entry and Entry Documents; Electronic Manifest Requirements for..., and Overflying the United States § 122.48 Air cargo manifest. (a) When required. Except as provided...

  16. 19 CFR 122.48 - Air cargo manifest.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 19 Customs Duties 1 2010-04-01 2010-04-01 false Air cargo manifest. 122.48 Section 122.48 Customs... AIR COMMERCE REGULATIONS Aircraft Entry and Entry Documents; Electronic Manifest Requirements for..., and Overflying the United States § 122.48 Air cargo manifest. (a) When required. Except as provided...

  17. 40 CFR 262.23 - Use of the manifest.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... returned to the generator by the designated facility (following the procedures of 40 CFR 264.72(f) or 265...) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.23 Use of the manifest. (a) The generator must: (1) Sign the manifest certification by hand; and (2) Obtain the handwritten signature of...

  18. 40 CFR 262.23 - Use of the manifest.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... returned to the generator by the designated facility (following the procedures of 40 CFR 264.72(f) or 265...) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.23 Use of the manifest. (a) The generator must: (1) Sign the manifest certification by hand; and (2) Obtain the handwritten signature of...

  19. 40 CFR 262.23 - Use of the manifest.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... returned to the generator by the designated facility (following the procedures of 40 CFR 264.72(f) or 265...) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.23 Use of the manifest. (a) The generator must: (1) Sign the manifest certification by hand; and (2) Obtain the handwritten signature of...

  20. 40 CFR 262.24 - Use of the electronic manifest.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... compliance with 49 CFR 177.817, a generator originating an electronic manifest must also provide the initial... (CONTINUED) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.24 Use of the electronic... requirement in these regulations for a generator to keep or retain a copy of each manifest is satisfied...

  1. 40 CFR 262.23 - Use of the manifest.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... returned to the generator by the designated facility (following the procedures of 40 CFR 264.72(f) or 265...) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.23 Use of the manifest. (a) The generator must: (1) Sign the manifest certification by hand; and (2) Obtain the handwritten signature of...

  2. 40 CFR 262.23 - Use of the manifest.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... returned to the generator by the designated facility (following the procedures of 40 CFR 264.72(f) or 265...) STANDARDS APPLICABLE TO GENERATORS OF HAZARDOUS WASTE The Manifest § 262.23 Use of the manifest. (a) The generator must: (1) Sign the manifest certification by hand; and (2) Obtain the handwritten signature of...

  3. Warm Debris Disks with WISE and HST

    NASA Astrophysics Data System (ADS)

    Padgett, Deborah; Stapelfeldt, Karl

    2016-01-01

    Using 22 μm data from the Wide Field Infrared Survey Explorer (WISE), we have completed a sensitive all-sky survey for debris disks in Hipparcos and Tycho catalog stars within 120 pc. This warm excess emission traces material in the circumstellar region likely to host terrestrial planets. Several hundred previously unknown debris disk candidates were identified. We are currently performing follow-up observations to characterize the stars, companions, and circumstellar material in these systems with a variety of facilities including Keck, Herschel, and HST. Thirteen WISE debris disks have been observed to date using HST/STIS coronagraphy. Five of these disks have been detected in scattered light. One is a large and highly asymmetric edge-on disk which appears to be both warped and bifurcated.

  4. A circumstellar disk around Beta Pictoris

    NASA Technical Reports Server (NTRS)

    Smith, B. A.; Terrile, R. J.

    1984-01-01

    A circumstellar disk has been observed optically around the fourth-magnitude star Beta Pictoris. First detected in the infrared by the Infrared Astronomy Satellite last year, the disk is seen to extend to more than 400 astronomical units from the star, or more than twice the distance measured in the infrared by the Infrared Astronomy Satellite. The disk is presented to earth almost edge-on and is composed of solid particles in nearly coplanar orbits. The observed change in surface brightness with distance from the star implies that the mass density of the disk falls off with approximately the third power of the radius. Because the circumstellar material is in the form of a highly flattened disk rather than a spherical shell, it is presumed to be associated with planet formation. It seems likely that the system is relatively young and that planet formation either is occurring now around Beta Pictoris or has recently been completed.

  5. About detection of precessing circumpulsar disks

    NASA Astrophysics Data System (ADS)

    Grimani, Catia

    2016-05-01

    Detections of circumpulsar disks and planetary systems through electromagnetic observations appear quite rare. In the case of PSR 1931+24 and B0656+14, the hypothesis of a precessing disk penetrating the pulsar light cylinder is found consistent with radio and gamma observations from these stars. Disk self-occultation and precession may affect electromagnetic measurements. We investigate here under which conditions gravitational waves generated by circumpulsar disk precession may be detected by the proposed second generation space interferometers DECIGO (DECI-hertz Interferometer Gravitational Wave Observatory) and BBO (Big Bang Observer). The characteristics of circumpulsar detectable precessing disks are estimated as a function of distance from the Solar System. Speculations on detection rates are presented.

  6. Rossby Wave Instability in Astrophysical Disks

    NASA Astrophysics Data System (ADS)

    Lovelace, Richard; Li, Hui

    2014-10-01

    A brief review is given of the Rossby wave instability in astrophysical disks. In non-self-gravitating discs, around for example a newly forming stars, the instability can be triggered by an axisymmetric bump at some radius r0 in the disk surface mass-density. It gives rise to exponentially growing non-axisymmetric perturbation (proportional to Exp[im ϕ], m = 1,2,...) in the vicinity of r0 consisting of anticyclonic vortices. These vortices are regions of high pressure and consequently act to trap dust particles which in turn can facilitate planetesimal growth in protoplanetary disks. The Rossby vortices in the disks around stars and black holes may cause the observed quasi-periodic modulations of the disk's thermal emission. Stirling Colgate's long standing interest in all types of vortices - particularly tornados - had an important part in stimulating the research on the Rossby wave instability.

  7. Observational constraints on black hole accretion disks

    NASA Technical Reports Server (NTRS)

    Liang, Edison P.

    1994-01-01

    We review the empirical constraints on accretion disk models of stellar-mass black holes based on recent multiwavelength observational results. In addition to time-averaged emission spectra, the time evolutions of the intensity and spectrum provide critical information about the structure, stability, and dynamics of the disk. Using the basic thermal Keplerian disk paradigm, we consider in particular generalizations of the standard optically thin disk models needed to accommodate the extremely rich variety of dynamical phenomena exhibited by black hole candidates ranging from flares of electron-positron annihilations and quasiperiodic oscillations in the X-ray intensity to X-ray novae activity. These in turn provide probes of the disk structure and global geometry. The goal is to construct a single unified framework to interpret a large variety of black hole phenomena. This paper will concentrate on the interface between basic theory and observational data modeling.

  8. The Kozai-Lidov mechanism in hydrodynamical disks. II. Effects of binary and disk parameters

    DOE PAGESBeta

    Fu, Wen; Lubow, Stephen H.; Martin, Rebecca G.

    2015-07-01

    Martin et al. (2014b) showed that a substantially misaligned accretion disk around one component of a binary system can undergo global damped Kozai–Lidov (KL) oscillations. During these oscillations, the inclination and eccentricity of the disk are periodically exchanged. However, the robustness of this mechanism and its dependence on the system parameters were unexplored. In this paper, we use three-dimensional hydrodynamical simulations to analyze how various binary and disk parameters affect the KL mechanism in hydrodynamical disks. The simulations include the effect of gas pressure and viscosity, but ignore the effects of disk self-gravity. We describe results for different numerical resolutions,more » binary mass ratios and orbital eccentricities, initial disk sizes, initial disk surface density profiles, disk sound speeds, and disk viscosities. We show that the KL mechanism can operate for a wide range of binary-disk parameters. We discuss the applications of our results to astrophysical disks in various accreting systems.« less

  9. DISKS AROUND BROWN DWARFS IN THE EJECTION SCENARIO. I. DISK COLLISIONS IN TRIPLE SYSTEMS

    SciTech Connect

    Umbreit, Stefan; Henning, Thomas; Klahr, Hubert; Spurzem, Rainer; Mikkola, Seppo E-mail: henning@mpia.de E-mail: spurzem@ari.uni-heidelberg.de

    2011-12-20

    We investigate the fate of disks around brown dwarfs in the ejection scenario and the implications on their observable properties. For that purpose, a parameter study of close triple approaches leading to escape is carried out where the ejected body is surrounded by a low-mass disk. We analyze the recircularized radial surface density profile of the post-encounter disk in dependence of the minimum two-body distances between the escaper and the perturbing bodies. Our results show that the general appearance of the disks is rather similar to disks after two-body encounters in as much as there is also an exponential drop in surface density for the outer disk regions as well as an enhancement of surface density for the innermost region relative to the initial disk profile. However, the disks after close triple approaches are mostly less massive, have generally flatter recircularized surface density disk profiles, and have radii that are similar or larger compared to disks after two-body encounters. From our results, we construct a simple scale-free model only depending on the minimum encounter distances of the two perturbers. Such a model is especially useful for statistical studies of disk collisions in triple systems that must cover a large range of encounter distances.

  10. [Psychiatric manifestations by prions. A narrative review].

    PubMed

    Carrillo Robles, Daniel; García Maldonado, Gerardo

    2016-01-01

    Prion diseases are a group of rare and rapidly progressive neurodegenerative conditions that may cause neuropsychiatric symptoms. This group of diseases has been described since the 18(th) century, but they were recognized decades later, when it became clear that the humans were affected by infected animals. There was controversy when the problem was attributed to a single protein with infective capacity. The common pathological process is characterized by the conversion of the normal cellular prion protein into an abnormal form. In humans, the illness has been classified as idiopathic, inherited and acquired through exposure to exogenous material containing abnormal prions. The most prominent neurological manifestation of prion diseases is the emergence of a rapidly progressive dementia, mioclonus associated with cerebellar ataxia and also extra pyramidal symptoms. Psychiatric symptoms occur in early stages of the illness and can contribute to timely diagnosis of this syndrome. Psychiatric symptoms have traditionally been grouped in three categories: affective symptoms, impaired motor function and psychotic symptoms. Such events usually occur during the prodromal period prior to the neurological manifestations and consists in the presence of social isolation, onset of delusions, irritability/aggression, visual hallucinations, anxiety and depression, and less frequent first-rank symptoms among others. Definite diagnosis requires post mortem examination. The possibility that a large number of cases may occur in the next years or that many cases have not been considered with this diagnosis is a fact. In our opinion, psychiatrists should be aware of symptoms of this disease. The main objective of this research consisted of assessing the correlation between this disturbance and neuro-psychiatric symptoms and particularly if this psychiatric manifestations integrate a clinical picture suggestive for the diagnosis of these diseases, but firstly reviewed taxonomic

  11. Do Accretion Disks Exist in High Energy Astrophysics?

    NASA Astrophysics Data System (ADS)

    Coppi, B.

    2006-10-01

    The familiar concept of an accretion disk is based on its gas dynamic description where, in particular, the vertical equilibrium is maintained by the (weak) vertical component of the gravitational force due to the central object. When a plasma structure differentially rotating around the same kind of object is considered in which the magnetic field diffusion due to finite resistivity is realistically weak, a radially periodic sequence of pairs of opposite current channels is found. Moreover, the vertical confinement of the structure is maintained by the resulting Lorentz force rather than by gravity. Thus, a ``Lorentz compression'' occurs. In addition, sequences of plasma rings^2 rather than disks emerge. (Note that H. Alfvén had proposed that planetary rings may be ``fossils'' of pre- existing envisioned plasma rings. Moreover, a large ring is the most prominent feature emerging from the high resolution X- ray image of the Crab). The ``seed'' magnetic field in which the structure is immersed is considerably smaller than that produced by the internal toroidal currents. The magnetic pressure is of the order of the plasma pressure. Thus, ring sequence configurations can be suitable for the emergence of a jet from their center. Two coupled non-linear equations have been solved, representing the vertical and the horizontal equilibrium conditions for the structure.*Sponsored in part by the U.S. D.O.E. B. Coppi, Phys. Plasmas 12, 057301, (2005) B. Coppi and F. Rousseau, Ap. J. 641 (1), 458 (2006)

  12. Vibration-Based Data Used to Detect Cracks in Rotating Disks

    NASA Technical Reports Server (NTRS)

    Gyekenyesi, Andrew L.; Sawicki, Jerzy T.; Martin, Richard E.; Baaklini, George Y.

    2004-01-01

    extremely limited, and the basic foundation of the methodology has not been fully studied. The NDE group is working on developing this foundation on the basis of theoretical modeling as well as experimental data by using the newly constructed subscale spin system shown in the preceding photograph. This, in turn, involved designing an optimal sub-scale disk that was meant to represent a full-scale turbine disk; conducting finite element analyses of undamaged and damaged disks to define the disk's deformation and the resulting shift in center of mass; and creating a rotordynamic model of the complete disk and shaft assembly to confirm operation beyond the first critical concerning the subscale experimental setup. The finite element analysis data, defining the center of mass shift due to disk damage, are shown. As an example, the change in the center of mass for a disk spinning at 8000 rpm with a 0.963-in. notch was 1.3 x 10(exp -4) in. The actual vibration response of an undamaged disk as well as the theoretical response of a cracked disk is shown. Experiments with cracked disks are continuing, and new approaches for analyzing the captured vibration data are being developed to better detect damage in a rotor. In addition, the subscale spin system is being used to test the durability and sensitivity of new NDE sensors that focus on detecting localized damage. This is designed to supplement the global response of the crack-detection methodology described here.

  13. Turbine inter-disk cavity cooling air compressor

    DOEpatents

    Chupp, Raymond E.; Little, David A.

    1998-01-01

    The inter-disk cavity between turbine rotor disks is used to pressurize cooling air. A plurality of ridges extend radially outwardly over the face of the rotor disks. When the rotor disks are rotated, the ridges cause the inter-disk cavity to compress air coolant flowing through the inter-disk cavity en route to the rotor blades. The ridges eliminate the need for an external compressor to pressurize the air coolant.

  14. Turbine inter-disk cavity cooling air compressor

    DOEpatents

    Chupp, R.E.; Little, D.A.

    1998-01-06

    The inter-disk cavity between turbine rotor disks is used to pressurize cooling air. A plurality of ridges extend radially outwardly over the face of the rotor disks. When the rotor disks are rotated, the ridges cause the inter-disk cavity to compress air coolant flowing through the inter-disk cavity en route to the rotor blades. The ridges eliminate the need for an external compressor to pressurize the air coolant. 5 figs.

  15. Double-Disk Dark Matter

    NASA Astrophysics Data System (ADS)

    Fan, JiJi; Katz, Andrey; Randall, Lisa; Reece, Matthew

    2013-09-01

    Based on observational tests of large scale structure and constraints on halo structure, dark matter is generally taken to be cold and essentially collisionless. On the other hand, given the large number of particles and forces in the visible world, a more complex dark sector could be a reasonable or even likely possibility. This hypothesis leads to testable consequences, perhaps portending the discovery of a rich hidden world neighboring our own. We consider a scenario that readily satisfies current bounds that we call Partially Interacting Dark Matter (PIDM). This scenario contains self-interacting dark matter, but it is not the dominant component. Even if PIDM contains only a fraction of the net dark matter density, comparable to the baryonic fraction, the subdominant component’s interactions can lead to interesting and potentially observable consequences. Our primary focus will be the special case of Double-Disk Dark Matter (DDDM), in which self-interactions allow the dark matter to lose enough energy to lead to dynamics similar to those in the baryonic sector. We explore a simple model in which DDDM can cool efficiently and form a disk within galaxies, and we evaluate some of the possible observational signatures. The most prominent signal of such a scenario could be an enhanced indirect detection signature with a distinctive spatial distribution. Even though subdominant, the enhanced density at the center of the galaxy and possibly throughout the plane of the galaxy (depending on precise alignment) can lead to large boost factors, and could even explain a signature as large as the 130 GeV Fermi line. Such scenarios also predict additional dark radiation degrees of freedom that could soon be detectable and would influence the interpretation of future data, such as that from Planck and from the Gaia satellite. We consider this to be the first step toward exploring a rich array of new possibilities for dark matter dynamics.

  16. Applications in quenching heat transfer: Liquid quenching of turbine disks and chill down in cryogenic fluid transfer lines

    NASA Astrophysics Data System (ADS)

    Cross, Matthew Fitch

    Liquid quenching of turbine disks concerns multiphase heat transfer (HT) during heat treating in the manufacture of gas turbine disks. Chill down (CD) in cryogenic fluid transfer lines concerns rapid cooling of cryogenic propulsion systems during startup. Quenching experiments were conducted on gas turbine disk models to obtain internal and surface temperatures. Three different disk models were tested and analyzed. The three disk models represent steps in the evolution from a simple disk shape to a scale model of an actual gas turbine disk. Experimental temperature data were used in finite element models of the disks to calculate heat transfer coefficients (h). Analysis of h for all of the quench cases studied led to a better understanding of the mechanisms of quenching HT. Insight into the mechanisms of quenching HT and the effects of forced quenchant flow led to generalizations of h with respect to local disk geometry. Correlations for single-phase and boiling HT were developed for selected quench cases. Recommendations for further study of this interesting and challenging topic are given. A numerical model to predict CD in cryogenic transfer lines was developed. Three CD cases using hydrogen are solved: (1) a simplified model amenable to analytical solution, (2) a realistic model of superheated vapor flow, and (3) a realistic model of initially subcooled liquid flow. The first case enables a comparison of the numerical model results with an analytical solution. The other cases are numerical models which provide quantities of interest in CD applications. For example, of great interest in CD applications is the ability to predict accurate values of CD time (the time required to achieve steady-state cryogenic flow). Sample CD times and other results of interest are discussed in the thesis.

  17. Finite Element Analysis Code

    Energy Science and Technology Software Center (ESTSC)

    2006-03-08

    MAPVAR-KD is designed to transfer solution results from one finite element mesh to another. MAPVAR-KD draws heavily from the structure and coding of MERLIN II, but it employs a new finite element data base, EXODUS II, and offers enhanced speed and new capabilities not available in MERLIN II. In keeping with the MERLIN II documentation, the computational algorithms used in MAPVAR-KD are described. User instructions are presented. Example problems are included to demonstrate the operationmore » of the code and the effects of various input options. MAPVAR-KD is a modification of MAPVAR in which the search algorithm was replaced by a kd-tree-based search for better performance on large problems.« less

  18. Accurate Finite Difference Algorithms

    NASA Technical Reports Server (NTRS)

    Goodrich, John W.

    1996-01-01

    Two families of finite difference algorithms for computational aeroacoustics are presented and compared. All of the algorithms are single step explicit methods, they have the same order of accuracy in both space and time, with examples up to eleventh order, and they have multidimensional extensions. One of the algorithm families has spectral like high resolution. Propagation with high order and high resolution algorithms can produce accurate results after O(10(exp 6)) periods of propagation with eight grid points per wavelength.

  19. Disk-loss and disk-renewal phases in classical Be stars. II. Contrasting with stable and variable disks

    SciTech Connect

    Draper, Zachary H.; Wisniewski, John P.; Bjorkman, Karen S.; Bjorkman, Jon E.; Meade, Marilyn R.; Haubois, Xavier; Mota, Bruno C.; Carciofi, Alex C. E-mail: karen.bjorkman@utoledo.edu E-mail: meade@astro.wisc.edu E-mail: carciofi@usp.br

    2014-05-10

    Recent observational and theoretical studies of classical Be stars have established the utility of polarization color diagrams (PCDs) in helping to constrain the time-dependent mass decretion rates of these systems. We expand on our pilot observational study of this phenomenon, and report the detailed analysis of a long-term (1989-2004) spectropolarimetric survey of nine additional classical Be stars, including systems exhibiting evidence of partial disk-loss/disk-growth episodes as well as systems exhibiting long-term stable disks. After carefully characterizing and removing the interstellar polarization along the line of sight to each of these targets, we analyze their intrinsic polarization behavior. We find that many steady-state Be disks pause at the top of the PCD, as predicted by theory. We also observe sharp declines in the Balmer jump polarization for later spectral type, near edge-on steady-state disks, again as recently predicted by theory, likely caused when the base density of the disk is very high, and the outer region of the edge-on disk starts to self absorb a significant number of Balmer jump photons. The intrinsic V-band polarization and polarization position angle of γ Cas exhibits variations that seem to phase with the orbital period of a known one-armed density structure in this disk, similar to the theoretical predictions of Halonen and Jones. We also observe stochastic jumps in the intrinsic polarization across the Balmer jump of several known Be+sdO systems, and speculate that the thermal inflation of part of the outer region of these disks could be responsible for producing this observational phenomenon. Finally, we estimate the base densities of this sample of stars to be between ≈8 × 10{sup –11} and ≈4 × 10{sup –12} g cm{sup –3} during quasi steady state periods given there maximum observed polarization.

  20. Twisted mass finite volume effects

    SciTech Connect

    Colangelo, Gilberto; Wenger, Urs; Wu, Jackson M. S.

    2010-08-01

    We calculate finite-volume effects on the pion masses and decay constant in twisted mass lattice QCD at finite lattice spacing. We show that the lighter neutral pion in twisted mass lattice QCD gives rise to finite-volume effects that are exponentially enhanced when compared to those arising from the heavier charged pions. We demonstrate that the recent two flavor twisted mass lattice data can be better fitted when twisted mass effects in finite-volume corrections are taken into account.