PSR J1618-3921: a recycled pulsar in an eccentric orbit

Science.gov (United States)

Octau, F.; Cognard, I.; Guillemot, L.; Tauris, T. M.; Freire, P. C. C.; Desvignes, G.; Theureau, G.

2018-04-01

Context. The 11.99 ms pulsar PSR J1618-3921 orbits a He white dwarf companion of probably low mass with a period of 22.7 d. The pulsar was discovered in a survey of the intermediate Galactic latitudes at 1400 MHz that was conducted with the Parkes radio telescope in the late 1990s. Although PSR J1618-3921 was discovered more than 15 years ago, only limited information has been published about this pulsar, which has a surprisingly high orbital eccentricity (e ≃ 0.027) considering its high spin frequency and the likely low mass of the companion. Aims: The focus of this work is a precise measurement of the spin and the astrometric and orbital characteristics of PSR J1618-3921. This was done with timing observations made at the Nançay Radio Telescope from 2009 to 2017. Methods: We analyzed the timing data recorded at the Nançay Radio Telescope over several years to characterize the properties of PSR J1618-3921. A rotation ephemeris for this pulsar was obtained by analyzing the arrival times of the radio pulses at the telescope. Results: We confirm the unusual eccentricity of PSR J1618-3921 and discuss several hypotheses regarding its formation in the context of other discoveries of recycled pulsars in eccentric orbits.

On the orbital eccentricity of V477 Cygni

International Nuclear Information System (INIS)

Scarfe, C.D.; Barlow, D.J.; Niehaus, R.J.

1976-01-01

The eclipsing binary V477 Cygni (BD+31 0 3932) is a Main-Sequence system with unequal components, a substantial orbital eccentricity and clearly detectable apsidal rotation. Recent photoelectric times of minima support the value e=0.3 obtained by O'Connell (1970). The lower value obtained by Budding (1974) is ruled out. (Auth.)

Effects of the Eccentricity of a Perturbing Third Body on the Orbital Correction Maneuvers of a Spacecraft

Directory of Open Access Journals (Sweden)

R. C. Domingos

2014-01-01

Full Text Available The fuel consumption required by the orbital maneuvers when correcting perturbations on the orbit of a spacecraft due to a perturbing body was estimated. The main goals are the measurement of the influence of the eccentricity of the perturbing body on the fuel consumption required by the station keeping maneuvers and the validation of the averaged methods when applied to the problem of predicting orbital maneuvers. To study the evolution of the orbits, the restricted elliptic three-body problem and the single- and double-averaged models are used. Maneuvers are made by using impulsive and low thrust maneuvers. The results indicated that the averaged models are good to make predictions for the orbital maneuvers when the spacecraft is in a high inclined orbit. The eccentricity of the perturbing body plays an important role in increasing the effects of the perturbation and the fuel consumption required for the station keeping maneuvers. It is shown that the use of more frequent maneuvers decreases the annual cost of the station keeping to correct the orbit of a spacecraft. An example of an eccentric planetary system of importance to apply the present study is the dwarf planet Haumea and its moons, one of them in an eccentric orbit.

Distant retrograde orbits and the asteroid hazard

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Perozzi, Ettore; Ceccaroni, Marta; Valsecchi, Giovanni B.; Rossi, Alessandro

2017-08-01

Distant Retrograde Orbits (DROs) gained a novel wave of fame in space mission design because of their numerous advantages within the framework of the US plans for bringing a large asteroid sample in the vicinity of the Earth as the next target for human exploration. DROs are stable solutions of the three-body problem that can be used whenever an object, whether of natural or artificial nature, is required to remain in the neighborhood of a celestial body without being gravitationally captured by it. As such, they represent an alternative option to Halo orbits around the collinear Lagrangian points L1 and L2. Also known under other names ( e.g., quasi-satellite orbits, cis-lunar orbits, family- f orbits) these orbital configurations found interesting applications in several mission profiles, like that of a spacecraft orbiting around the small irregularly shaped satellite of Mars Phobos or the large Jovian moon Europa. In this paper a basic explanation of the DRO dynamics is presented in order to clarify some geometrical properties that characterize them. Their accessibility is then discussed from the point of view of mission analysis under different assumptions. Finally, their relevance within the framework of the present asteroid hazard protection programs is shown, stressing the significant increase in warning time they would provide in the prediction of impactors coming from the direction of the Sun.

An interstellar origin for Jupiter's retrograde co-orbital asteroid

Science.gov (United States)

Namouni, F.; Morais, M. H. M.

2018-06-01

Asteroid (514107) 2015 BZ509 was discovered recently in Jupiter's co-orbital region with a retrograde motion around the Sun. The known chaotic dynamics of the outer Solar system have so far precluded the identification of its origin. Here, we perform a high-resolution statistical search for stable orbits and show that asteroid (514107) 2015 BZ509 has been in its current orbital state since the formation of the Solar system. This result indicates that (514107) 2015 BZ509 was captured from the interstellar medium 4.5 billion years in the past as planet formation models cannot produce such a primordial large-inclination orbit with the planets on nearly coplanar orbits interacting with a coplanar debris disc that must produce the low-inclination small-body reservoirs of the Solar system such as the asteroid and Kuiper belts. This result also implies that more extrasolar asteroids are currently present in the Solar system on nearly polar orbits.

A complete waveform model for compact binaries on eccentric orbits

Science.gov (United States)

George, Daniel; Huerta, Eliu; Kumar, Prayush; Agarwal, Bhanu; Schive, Hsi-Yu; Pfeiffer, Harald; Chu, Tony; Boyle, Michael; Hemberger, Daniel; Kidder, Lawrence; Scheel, Mark; Szilagyi, Bela

2017-01-01

We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are non-spinning, and which evolve on orbits with low to moderate eccentricity. We show that this inspiral-merger-ringdown waveform model reproduces the effective-one-body model for black hole binaries with mass-ratios between 1 to 15 in the zero eccentricity limit over a wide range of the parameter space under consideration. We use this model to show that the gravitational wave transients GW150914 and GW151226 can be effectively recovered with template banks of quasicircular, spin-aligned waveforms if the eccentricity e0 of these systems when they enter the aLIGO band at a gravitational wave frequency of 14 Hz satisfies e0GW 150914 <= 0 . 15 and e0GW 151226 <= 0 . 1 .

The Transit Ingress and the Tilted Orbit of the Extraordinarily Eccentric Exoplanet HD 80606b

Science.gov (United States)

Winn, Joshua N.; Howard, Andrew W.; Johnson, John A.; Marcy, Geoffrey W.; Gazak, J. Zachary; Starkey, Donn; Ford, Eric B.; Colon, Knicole D.; Reyes, Francisco; Nortmann, Lisa;

NEXT GENERATION OF TELESCOPES OR DYNAMICS REQUIRED TO DETERMINE IF EXO-MOONS HAVE PROGRADE OR RETROGRADE ORBITS

International Nuclear Information System (INIS)

Lewis, Karen M.; Fujii, Yuka

2014-01-01

We survey the methods proposed in the literature for detecting moons of extrasolar planets in terms of their ability to distinguish between prograde and retrograde moon orbits, an important tracer of the moon formation channel. We find that most moon detection methods, in particular, sensitive methods for detecting moons of transiting planets, cannot observationally distinguishing prograde and retrograde moon orbits. The prograde and retrograde cases can only be distinguished where the dynamical evolution of the orbit due to, e.g., three body effects is detectable, where one of the two cases is dynamically unstable, or where new observational facilities, which can implement a technique capable of differentiating the two cases, come online. In particular, directly imaged planets are promising targets because repeated spectral and photometric measurements, which are required to determine moon orbit direction, could also be conducted with the primary interest of characterizing the planet itself

Einstein@Home DISCOVERY OF A PALFA MILLISECOND PULSAR IN AN ECCENTRIC BINARY ORBIT

Energy Technology Data Exchange (ETDEWEB)

Knispel, B.; Allen, B. [Leibniz Universität, Hannover, D-30167 Hannover (Germany); Lyne, A. G.; Stappers, B. W. [Jodrell Bank Centre for Astrophysics, School of Physics and Astronomy, University of Manchester, Manchester, M13 9PL (United Kingdom); Freire, P. C. C.; Lazarus, P. [Max-Planck-Institut für Radioastronomie, Auf dem Hügel 69, D-53121 Bonn (Germany); Aulbert, C.; Bock, O.; Eggenstein, H.-B.; Fehrmann, H. [Max-Planck-Institut für Gravitationsphysik, Callinstr. 38, D-30167 Hannover (Germany); Bogdanov, S.; Camilo, F. [Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027 (United States); Brazier, A.; Chatterjee, S.; Cordes, J. M. [Department of Astronomy and Center for Radiophysics and Space Research, Cornell University, Ithaca, NY 14853 (United States); Cardoso, F. [Department of Physics and Astronomy, West Virginia University, Morgantown, WV 26506 (United States); Crawford, F. [Department of Physics and Astronomy, Franklin and Marshall College, Lancaster, PA 17604-3003 (United States); Deneva, J. S. [National Research Council, resident at the Naval Research Laboratory, Washington, DC 20375 (United States); Ferdman, R. [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Hessels, J. W. T., E-mail: benjamin.knispel@aei.mpg.de [ASTRON, Netherlands Institute for Radio Astronomy, Postbus 2, 7990 AA, Dwingeloo (Netherlands); and others

2015-06-10

We report the discovery of the millisecond pulsar (MSP) PSR J1950+2414 (P = 4.3 ms) in a binary system with an eccentric (e = 0.08) 22 day orbit in Pulsar Arecibo L-band Feed Array survey observations with the Arecibo telescope. Its companion star has a median mass of 0.3 M{sub ⊙} and is most likely a white dwarf (WD). Fully recycled MSPs like this one are thought to be old neutron stars spun-up by mass transfer from a companion star. This process should circularize the orbit, as is observed for the vast majority of binary MSPs, which predominantly have orbital eccentricities e < 0.001. However, four recently discovered binary MSPs have orbits with 0. 027 < e < 0.44; PSR J1950+2414 is the fifth such system to be discovered. The upper limits for its intrinsic spin period derivative and inferred surface magnetic field strength are comparable to those of the general MSP population. The large eccentricities are incompatible with the predictions of the standard recycling scenario: something unusual happened during their evolution. Proposed scenarios are (a) initial evolution of the pulsar in a triple system which became dynamically unstable, (b) origin in an exchange encounter in an environment with high stellar density, (c) rotationally delayed accretion-induced collapse of a super-Chandrasekhar WD, and (d) dynamical interaction of the binary with a circumbinary disk. We compare the properties of all five known eccentric MSPs with the predictions of these formation channels. Future measurements of the masses and proper motion might allow us to firmly exclude some of the proposed formation scenarios.

Topology of the Relative Motion: Circular and Eccentric Reference Orbit Cases

Science.gov (United States)

FontdecabaiBaig, Jordi; Metris, Gilles; Exertier, Pierre

2007-01-01

This paper deals with the topology of the relative trajectories in flight formations. The purpose is to study the different types of relative trajectories, their degrees of freedom, and to give an adapted parameterization. The paper also deals with the research of local circular motions. Even if they exist only when the reference orbit is circular, we extrapolate initial conditions to the eccentric reference orbit case.This alternative approach is complementary with traditional approaches in terms of cartesian coordinates or differences of orbital elements.

Complete waveform model for compact binaries on eccentric orbits

Science.gov (United States)

Huerta, E. A.; Kumar, Prayush; Agarwal, Bhanu; George, Daniel; Schive, Hsi-Yu; Pfeiffer, Harald P.; Haas, Roland; Ren, Wei; Chu, Tony; Boyle, Michael; Hemberger, Daniel A.; Kidder, Lawrence E.; Scheel, Mark A.; Szilagyi, Bela

2017-01-01

We present a time domain waveform model that describes the inspiral, merger and ringdown of compact binary systems whose components are nonspinning, and which evolve on orbits with low to moderate eccentricity. The inspiral evolution is described using third-order post-Newtonian equations both for the equations of motion of the binary, and its far-zone radiation field. This latter component also includes instantaneous, tails and tails-of-tails contributions, and a contribution due to nonlinear memory. This framework reduces to the post-Newtonian approximant TaylorT4 at third post-Newtonian order in the zero-eccentricity limit. To improve phase accuracy, we also incorporate higher-order post-Newtonian corrections for the energy flux of quasicircular binaries and gravitational self-force corrections to the binding energy of compact binaries. This enhanced prescription for the inspiral evolution is combined with a fully analytical prescription for the merger-ringdown evolution constructed using a catalog of numerical relativity simulations. We show that this inspiral-merger-ringdown waveform model reproduces the effective-one-body model of Ref. [Y. Pan et al., Phys. Rev. D 89, 061501 (2014)., 10.1103/PhysRevD.89.061501] for quasicircular black hole binaries with mass ratios between 1 to 15 in the zero-eccentricity limit over a wide range of the parameter space under consideration. Using a set of eccentric numerical relativity simulations, not used during calibration, we show that our new eccentric model reproduces the true features of eccentric compact binary coalescence throughout merger. We use this model to show that the gravitational-wave transients GW150914 and GW151226 can be effectively recovered with template banks of quasicircular, spin-aligned waveforms if the eccentricity e0 of these systems when they enter the aLIGO band at a gravitational-wave frequency of 14 Hz satisfies e0GW 150914≤0.15 and e0GW 151226≤0.1 . We also find that varying the spin

ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b

Energy Technology Data Exchange (ETDEWEB)

Lewis, Nikole K.; Showman, Adam P. [Department of Planetary Sciences and Lunar and Planetary Laboratory, The University of Arizona, Tucson, AZ 85721 (United States); Knutson, Heather A.; Desert, Jean-Michel; Kao, Melodie [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States); Laughlin, Gregory; Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Burrows, Adam; Bakos, Gaspar A.; Hartman, Joel D. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Crepp, Justin R. [Department of Physics, University of Notre Dame, Notre Dame, IN 46556 (United States); Mighell, Kenneth J. [National Optical Astronomy Observatories, Tucson, AZ 85726 (United States); Agol, Eric [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Charbonneau, David [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Fischer, Debra A. [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Hinkley, Sasha; Johnson, John Asher [Department of Astrophysics, California Institute of Technology, MC 249-17, Pasadena, CA 91125 (United States); Howard, Andrew W., E-mail: nklewis@mit.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); and others

2013-04-01

We present the first secondary eclipse and phase curve observations for the highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands of the Spitzer Space Telescope. The 3.6 and 4.5 {mu}m data sets span an entire orbital period of HAT-P-2b (P = 5.6334729 d), making them the longest continuous phase curve observations obtained to date and the first full-orbit observations of a planet with an eccentricity exceeding 0.2. We present an improved non-parametric method for removing the intrapixel sensitivity variations in Spitzer data at 3.6 and 4.5 {mu}m that robustly maps position-dependent flux variations. We find that the peak in planetary flux occurs at 4.39 {+-} 0.28, 5.84 {+-} 0.39, and 4.68 {+-} 0.37 hr after periapse passage with corresponding maxima in the planet/star flux ratio of 0.1138% {+-} 0.0089%, 0.1162% {+-} 0.0080%, and 0.1888% {+-} 0.0072% in the 3.6, 4.5, and 8.0 {mu}m bands, respectively. Our measured secondary eclipse depths of 0.0996% {+-} 0.0072%, 0.1031% {+-} 0.0061%, 0.071%{sub -0.013%}{sup +0.029,} and 0.1392% {+-} 0.0095% in the 3.6, 4.5, 5.8, and 8.0 {mu}m bands, respectively, indicate that the planet cools significantly from its peak temperature before we measure the dayside flux during secondary eclipse. We compare our measured secondary eclipse depths to the predictions from a one-dimensional radiative transfer model, which suggests the possible presence of a transient day side inversion in HAT-P-2b's atmosphere near periapse. We also derive improved estimates for the system parameters, including its mass, radius, and orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and radial velocity data allows us to determine the eccentricity (e = 0.50910 {+-} 0.00048) and argument of periapse ({omega} = 188. Degree-Sign 09 {+-} 0. Degree-Sign 39) of HAT-P-2b's orbit with a greater precision than has been achieved for any other eccentric extrasolar planet. We also find evidence for a long

ORBITAL PHASE VARIATIONS OF THE ECCENTRIC GIANT PLANET HAT-P-2b

International Nuclear Information System (INIS)

Lewis, Nikole K.; Showman, Adam P.; Knutson, Heather A.; Désert, Jean-Michel; Kao, Melodie; Cowan, Nicolas B.; Laughlin, Gregory; Fortney, Jonathan J.; Burrows, Adam; Bakos, Gáspár Á.; Hartman, Joel D.; Deming, Drake; Crepp, Justin R.; Mighell, Kenneth J.; Agol, Eric; Charbonneau, David; Fischer, Debra A.; Hinkley, Sasha; Johnson, John Asher; Howard, Andrew W.

2013-01-01

We present the first secondary eclipse and phase curve observations for the highly eccentric hot Jupiter HAT-P-2b in the 3.6, 4.5, 5.8, and 8.0 μm bands of the Spitzer Space Telescope. The 3.6 and 4.5 μm data sets span an entire orbital period of HAT-P-2b (P = 5.6334729 d), making them the longest continuous phase curve observations obtained to date and the first full-orbit observations of a planet with an eccentricity exceeding 0.2. We present an improved non-parametric method for removing the intrapixel sensitivity variations in Spitzer data at 3.6 and 4.5 μm that robustly maps position-dependent flux variations. We find that the peak in planetary flux occurs at 4.39 ± 0.28, 5.84 ± 0.39, and 4.68 ± 0.37 hr after periapse passage with corresponding maxima in the planet/star flux ratio of 0.1138% ± 0.0089%, 0.1162% ± 0.0080%, and 0.1888% ± 0.0072% in the 3.6, 4.5, and 8.0 μm bands, respectively. Our measured secondary eclipse depths of 0.0996% ± 0.0072%, 0.1031% ± 0.0061%, 0.071% -0.013% +0.029, and 0.1392% ± 0.0095% in the 3.6, 4.5, 5.8, and 8.0 μm bands, respectively, indicate that the planet cools significantly from its peak temperature before we measure the dayside flux during secondary eclipse. We compare our measured secondary eclipse depths to the predictions from a one-dimensional radiative transfer model, which suggests the possible presence of a transient day side inversion in HAT-P-2b's atmosphere near periapse. We also derive improved estimates for the system parameters, including its mass, radius, and orbital ephemeris. Our simultaneous fit to the transit, secondary eclipse, and radial velocity data allows us to determine the eccentricity (e = 0.50910 ± 0.00048) and argument of periapse (ω = 188.°09 ± 0.°39) of HAT-P-2b's orbit with a greater precision than has been achieved for any other eccentric extrasolar planet. We also find evidence for a long-term linear trend in the radial velocity data. This trend suggests the presence of

Extreme secular excitation of eccentricity inside mean motion resonance. Small bodies driven into star-grazing orbits by planetary perturbations

Science.gov (United States)

Pichierri, Gabriele; Morbidelli, Alessandro; Lai, Dong

2017-09-01

Context. It is well known that asteroids and comets fall into the Sun. Metal pollution of white dwarfs and transient spectroscopic signatures of young stars like β-Pic provide growing evidence that extra solar planetesimals can attain extreme orbital eccentricities and fall into their parent stars. Aims: We aim to develop a general, implementable, semi-analytical theory of secular eccentricity excitation of small bodies (planetesimals) in mean motion resonances with an eccentric planet valid for arbitrary values of the eccentricities and including the short-range force due to General Relativity. Methods: Our semi-analytic model for the restricted planar three-body problem does not make use of series expansion and therefore is valid for any eccentricity value and semi-major axis ratio. The model is based on the application of the adiabatic principle, which is valid when the precession period of the longitude of pericentre of the planetesimal is much longer than the libration period in the mean motion resonance. In resonances of order larger than 1 this is true except for vanishingly small eccentricities. We provide prospective users with a Mathematica notebook with implementation of the model allowing direct use. Results: We confirm that the 4:1 mean motion resonance with a moderately eccentric (e' ≲ 0.1) planet is the most powerful one to lift the eccentricity of planetesimals from nearly circular orbits to star-grazing ones. However, if the planet is too eccentric, we find that this resonance is unable to pump the planetesimal's eccentricity to a very high value. The inclusion of the General Relativity effect imposes a condition on the mass of the planet to drive the planetesimals into star-grazing orbits. For a planetesimal at 1 AU around a solar mass star (or white dwarf), we find a threshold planetary mass of about 17 Earth masses. We finally derive an analytical formula for this critical mass. Conclusions: Planetesimals can easily fall into the central star

Beyond the geodesic approximation: Conservative effects of the gravitational self-force in eccentric orbits around a Schwarzschild black hole

International Nuclear Information System (INIS)

Barack, Leor; Sago, Norichika

2011-01-01

We study conservative finite-mass corrections to the motion of a particle in a bound (eccentric) strong-field orbit around a Schwarzschild black hole. We assume the particle's mass μ is much smaller than the black hole mass M, and explore post-geodesic corrections of O(μ/M). Our analysis uses numerical data from a recently developed code that outputs the Lorenz-gauge gravitational self-force (GSF) acting on the particle along the eccentric geodesic. First, we calculate the O(μ/M) conservative correction to the periastron advance of the orbit, as a function of the (gauge-dependent) semilatus rectum and eccentricity. A gauge-invariant description of the GSF precession effect is made possible in the circular-orbit limit, where we express the correction to the periastron advance as a function of the invariant azimuthal frequency. We compare this relation with results from fully nonlinear numerical-relativistic simulations. In order to obtain a gauge-invariant measure of the GSF effect for fully eccentric orbits, we introduce a suitable generalization of Detweiler's circular-orbit ''redshift'' invariant. We compute the O(μ/M) conservative correction to this invariant, expressed as a function of the two invariant frequencies that parametrize the orbit. Our results are in good agreement with results from post-Newtonian calculations in the weak-field regime, as we shall report elsewhere. The results of our study can inform the development of analytical models for the dynamics of strongly gravitating binaries. They also provide an accurate benchmark for future numerical-relativistic simulations.

ECCENTRIC JUPITERS VIA DISK–PLANET INTERACTIONS

International Nuclear Information System (INIS)

Duffell, Paul C.; Chiang, Eugene

2015-01-01

Numerical hydrodynamics calculations are performed to determine the conditions under which giant planet eccentricities can be excited by parent gas disks. Unlike in other studies, Jupiter-mass planets are found to have their eccentricities amplified—provided their orbits start off as eccentric. We disentangle the web of co-rotation, co-orbital, and external resonances to show that this finite-amplitude instability is consistent with that predicted analytically. Ellipticities can grow until they reach of order of the disk's aspect ratio, beyond which the external Lindblad resonances that excite eccentricity are weakened by the planet's increasingly supersonic epicyclic motion. Forcing the planet to still larger eccentricities causes catastrophic eccentricity damping as the planet collides into gap walls. For standard parameters, the range of eccentricities for instability is modest; the threshold eccentricity for growth (∼0.04) is not much smaller than the final eccentricity to which orbits grow (∼0.07). If this threshold eccentricity can be lowered (perhaps by non-barotropic effects), and if the eccentricity driving documented here survives in 3D, it may robustly explain the low-to-moderate eccentricities ≲0.1 exhibited by many giant planets (including Jupiter and Saturn), especially those without planetary or stellar companions

THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. III. A PAUCITY OF PROTO-HOT JUPITERS ON SUPER-ECCENTRIC ORBITS

International Nuclear Information System (INIS)

Dawson, Rebekah I.; Murray-Clay, Ruth A.; Johnson, John Asher

2015-01-01

Gas giant planets orbiting within 0.1 AU of their host stars are unlikely to have formed in situ and are evidence for planetary migration. It is debated whether the typical hot Jupiter smoothly migrated inward from its formation location through the proto-planetary disk, or was perturbed by another body onto a highly eccentric orbit, which tidal dissipation subsequently shrank and circularized during close stellar passages. Socrates and collaborators predicted that the latter model should produce a population of super-eccentric proto-hot Jupiters readily observable by Kepler. We find a paucity of such planets in the Kepler sample, which is inconsistent with the theoretical prediction with 96.9% confidence. Observational effects are unlikely to explain this discrepancy. We find that the fraction of hot Jupiters with an orbital period P > 3 days produced by the star-planet Kozai mechanism does not exceed (at two-sigma) 44%. Our results may indicate that disk migration is the dominant channel for producing hot Jupiters with P > 3 days. Alternatively, the typical hot Jupiter may have been perturbed to a high eccentricity by interactions with a planetary rather than stellar companion, and began tidal circularization much interior to 1 AU after multiple scatterings. A final alternative is that early in the tidal circularization process at high eccentricities tidal circularization occurs much more rapidly than later in the process at low eccentricities, although this is contrary to current tidal theories

EMPIRICAL CONSTRAINTS ON TROJAN COMPANIONS AND ORBITAL ECCENTRICITIES IN 25 TRANSITING EXOPLANETARY SYSTEMS

International Nuclear Information System (INIS)

Madhusudhan, N.; Winn, Joshua N.

2009-01-01

We present a search for Trojan companions to 25 transiting exoplanets. We use the technique of Ford and Gaudi, in which a difference is sought between the observed transit time and the transit time that is calculated by fitting a two-body Keplerian orbit to the radial-velocity data. This technique is sensitive to the imbalance of mass at the L4/L5 points of the planet-star orbit. No companions were detected above 2σ confidence. The median 2σ upper limit is 56 M + , and the most constraining limit is 2.8 M + for the case of GJ 436. A similar survey using forthcoming data from the Kepler satellite mission, along with the radial-velocity data that will be needed to confirm transit candidates, will be sensitive to 10-50 M + Trojan companions in the habitable zones of their parent stars. As a by-product of this study, we present empirical constraints on the eccentricities of the planetary orbits, including those which have previously been assumed to be circular. The limits on eccentricity are of interest for investigations of tidal circularization and for bounding possible systematic errors in the measured planetary radii and the predicted times of secondary eclipses.

Antegrade or Retrograde Accessory Pathway Conduction: Who Dies First?

Directory of Open Access Journals (Sweden)

Claudio Hadid, MD

2012-05-01

Full Text Available A 36 year-old man with Wolff Parkinson White syndrome due to a left-sided accessory pathway (AP was referred for catheter ablation. Whether abolition of antegrade and retrograde AP conduction during ablation therapy occurs simultaneously, is unclear. At the ablation procedure, radiofrequency delivery resulted in loss of preexcitation followed by a short run of orthodromic tachycardia with eccentric atrial activation, demonstrating persistence of retrograde conduction over the AP after abolition of its antegrade conduction. During continued radiofrequency delivery at the same position, the fifth non-preexcitated beat failed to conduct retrogradely and the tachycardia ended. In this case, antegrade AP conduction was abolished earlier than retrograde conduction.

Overload control of artificial gravity facility using spinning tether system for high eccentricity transfer orbits

Science.gov (United States)

Gou, Xing-wang; Li, Ai-jun; Tian, Hao-chang; Wang, Chang-qing; Lu, Hong-shi

2018-06-01

As the major part of space life supporting systems, artificial gravity requires further study before it becomes mature. Spinning tether system is a good alternative solution to provide artificial gravity for the whole spacecraft other than additional devices, and its longer tether length could significantly reduce spinning velocity and thus enhance comfortability. An approximated overload-based feedback method is proposed to provide estimated spinning velocity signals for controller, so that gravity level could be accurately controlled without complicated GPS modules. System behavior in high eccentricity transfer orbits is also studied to give a complete knowledge of the spinning stabilities. The application range of the proposed method is studied in various orbit cases and spinning velocities, indicating that it is accurate and reliable for most of the mission phases especially for the final constant gravity level phase. In order to provide stable gravity level for transfer orbit missions, a sliding mode controller based on estimated angular signals is designed for closed-loop control. Numerical results indicate that the combination of overload-based feedback and sliding mode controller could satisfy most of the long-term artificial gravity missions. It is capable of forming flexible gravity environment in relatively good accuracy even in the lowest possible orbital radiuses and high eccentricity orbits of crewed space missions. The proposed scheme provides an effective tether solution for the artificial gravity construction in interstellar travel.

Mercury in Retrograde: Shaking Up the Study of Orbital Motion with Kinesthetic Learning

Science.gov (United States)

DeStefano, Paul; Allen, Thomas; Widenhorn, Ralf

2018-06-01

We are investigating the use of kinesthetic activities to teach the orbital motion of planets at the introductory astronomy level. In addition to breaking the monotony of traditional classroom settings, kinesthetic activities can allow novel connections to form between the student and the material, as established in a recent study. In our example active learning activity, two students walk along predetermined paths in the classroom, simulating the dynamics of any two real or fictional bodies in orbital motion about a common object. Each student carries a short-range, local positioning device that records its 2D position, continuously. The position data from both devices are collected on a single computer. After acquisition, the data can be used to highlight interesting features of orbital dynamics. For example, we demonstrate a particular transformation of the data that shows apparent retrograde motion arising directly from the relative motion of two bodies orbiting a common object. This activity provides students with the opportunity to observe interesting orbital dynamics on a human scale.

Dynamic Portrait of the Retrograde 1:1 Mean Motion Resonance

Science.gov (United States)

Huang, Yukun; Li, Miao; Li, Junfeng; Gong, Shengping

2018-06-01

Asteroids in mean motion resonances with giant planets are common in the solar system, but it was not until recently that several asteroids in retrograde mean motion resonances with Jupiter and Saturn were discovered. A retrograde co-orbital asteroid of Jupiter, 2015 BZ509 is confirmed to be in a long-term stable retrograde 1:1 mean motion resonance with Jupiter, which gives rise to our interests in its unique resonant dynamics. In this paper, we investigate the phase-space structure of the retrograde 1:1 resonance in detail within the framework of the circular restricted three-body problem. We construct a simple integrable approximation for the planar retrograde resonance using canonical contact transformation and numerically employ the averaging procedure in closed form. The phase portrait of the retrograde 1:1 resonance is depicted with the level curves of the averaged Hamiltonian. We thoroughly analyze all possible librations in the co-orbital region and uncover a new apocentric libration for the retrograde 1:1 resonance inside the planet’s orbit. We also observe the significant jumps in orbital elements for outer and inner apocentric librations, which are caused by close encounters with the perturber.

TRANSIT TIMING VARIATIONS FOR INCLINED AND RETROGRADE EXOPLANETARY SYSTEMS

International Nuclear Information System (INIS)

Payne, Matthew J.; Ford, Eric B.; Veras, Dimitri

2010-01-01

We perform numerical calculations of the expected transit timing variations (TTVs) induced on a hot-Jupiter by an Earth-mass perturber. Motivated by the recent discoveries of retrograde transiting planets, we concentrate on an investigation of the effect of varying relative planetary inclinations, up to and including completely retrograde systems. We find that planets in low-order (e.g., 2:1) mean-motion resonances (MMRs) retain approximately constant TTV amplitudes for 0 deg. 170 deg. Systems in higher order MMRs (e.g., 5:1) increase in TTV amplitude as inclinations increase toward 45 deg., becoming approximately constant for 45 deg. 135 deg. Planets away from resonance slowly decrease in TTV amplitude as inclinations increase from 0 deg. to 180 deg., whereas planets adjacent to resonances can exhibit a huge range of variability in TTV amplitude as a function of both eccentricity and inclination. For highly retrograde systems (135 deg. < i ≤ 180 deg.), TTV signals will be undetectable across almost the entirety of parameter space, with the exceptions occurring when the perturber has high eccentricity or is very close to an MMR. This high inclination decrease in TTV amplitude (on and away from resonance) is important for the analysis of the known retrograde and multi-planet transiting systems, as inclination effects need to be considered if TTVs are to be used to exclude the presence of any putative planetary companions: absence of evidence is not evidence of absence.

On the tidal interaction of massive extrasolar planets on highly eccentric orbits

Science.gov (United States)

Ivanov, P. B.; Papaloizou, J. C. B.

2004-01-01

In this paper we develop a theory of disturbances induced by the stellar tidal field in a fully convective slowly rotating planet orbiting on a highly eccentric orbit around a central star. In this case it is appropriate to treat the tidal influence as a succession of impulsive tidal interactions occurring at periastron passage. For a fully convective planet mainly the l= 2 fundamental mode of oscillation is excited. We show that there are two contributions to the mode energy and angular momentum gain due to impulsive tidal interaction: (i) `the quasi-static' contribution, which requires dissipative processes operating in the planet, and (ii) the dynamical contribution associated with excitation of modes of oscillation. These contributions are obtained self-consistently from a single set of the governing equations. We calculate a critical `equilibrium' value of angular velocity of the planet Ωcrit determined by the condition that action of the dynamic tides does not alter the angular velocity at this rotation rate. We show that this can be much larger than the corresponding rate associated with quasi-static tides and that at this angular velocity, the rate of energy exchange is minimized. We also investigate the conditions for the stochastic increase in oscillation energy that may occur if many periastron passages are considered and dissipation is not important. We provide a simple criterion for this instability to occur. Finally, we make some simple estimates of the time-scale of evolution of the orbital semimajor axis and circularization of the initially eccentric orbit due to tides, using a realistic model of the planet and its cooling history, for orbits with periods after circularization typical of those observed for extrasolar planets Pobs>~ 3 d. Quasi-static tides are found to be ineffective for semimajor axes >~0.1 au. On the other hand, dynamic tides could have produced a very large decrease of the semimajor axis of a planet with mass of the order of the

A numerical investigation on the eccentricity growth of GNSS disposal orbits

Science.gov (United States)

Alessi, E. M.; Deleflie, F.; Rosengren, A. J.; Rossi, A.; Valsecchi, G. B.; Daquin, J.; Merz, K.

2016-05-01

We present the results of an extensive numerical exploration performed on the eccentricity growth in MEO associated with two possible end-of-life disposal strategies for GNSS satellites. The study calls attention to the existence of values of initial inclination, longitude of ascending node, and argument of perigee that are more advantageous in terms of long-term stability of the orbit. The important role of the initial epoch and a corresponding periodicity are also shown. The present investigation is influential in view of recent analytical and numerical developments on the chaotic nature of the region due to lunisolar perturbations, but also for the upcoming Galileo and BeiDou constellations.

Frequency modulation reveals the phasing of orbital eccentricity during Cretaceous Oceanic Anoxic Event II and the Eocene hyperthermals

Czech Academy of Sciences Publication Activity Database

Laurin, Jiří; Meyers, S. R.; Galeotti, S.; Lanci, L.

2016-01-01

Roč. 442, 15 May (2016), s. 143-156 ISSN 0012-821X R&D Projects: GA MŠk LH12041 Institutional support: RVO:67985530 Keywords : orbital eccentricity * cyclostratigraphy * Cenomanian Subject RIV: DB - Geology ; Mineralogy Impact factor: 4.409, year: 2016

Tidal Disruption of Inclined or Eccentric Binaries by Massive Black Holes

Science.gov (United States)

Brown, Harriet; Kobayashi, Shiho; Rossi, Elena M.; Sari, Re'em

2018-04-01

Binary stars that are on close orbits around massive black holes (MBH) such as Sgr A* in the centre of the Milky Way are liable to undergo tidal disruption and eject a hypervelocity star. We study the interaction between such a MBH and circular binaries for general binary orientations and penetration depths (i.e. binaries penetrate into the tidal radius around the BH). We show that for very deep penetrators, almost all binaries are disrupted when the binary rotation axis is roughly oriented toward the BH or it is in the opposite direction. The surviving chance becomes significant when the angle between the binary rotation axis and the BH direction is between 0.15π and 0.85π. The surviving chance is as high as ˜20% when the binary rotation axis is perpendicular to the BH direction. However, for shallow penetrators, the highest disruption chance is found in such a perpendicular case, especially in the prograde case. This is because the dynamics of shallow penetrators is more sensitive to the relative orientation of the binary and orbital angular momenta. We provide numerical fits to the disruption probability and energy gain at the the BH encounter as a function of the penetration depth. The latter can be simply rescaled in terms of binary masses, their initial separation and the binary-to-BH mass ratio to evaluate the ejection velocity of a binary members in various systems. We also investigate the disruption of coplanar, eccentric binaries by a MBH. It is shown that for highly eccentric binaries retrograde orbits have a significantly increased disruption probability and ejection velocities compared to the circular binaries.

CONDITIONS OF PASSAGE AND ENTRAPMENT OF TERRESTRIAL PLANETS IN SPIN-ORBIT RESONANCES

International Nuclear Information System (INIS)

Makarov, Valeri V.

2012-01-01

The dynamical evolution of terrestrial planets resembling Mercury in the vicinity of spin-orbit resonances is investigated using comprehensive harmonic expansions of the tidal torque taking into account the frequency-dependent quality factors and Love numbers. The torque equations are integrated numerically with a small step in time, including the oscillating triaxial torque components but neglecting the layered structure of the planet and assuming a zero obliquity. We find that a Mercury-like planet with a current value of orbital eccentricity (0.2056) is always captured in 3:2 resonance. The probability of capture in the higher 2:1 resonance is approximately 0.23. These results are confirmed by a semi-analytical estimation of capture probabilities as functions of eccentricity for both prograde and retrograde evolutions of spin rate. As follows from analysis of equilibrium torques, entrapment in 3:2 resonance is inevitable at eccentricities between 0.2 and 0.41. Considering the phase space parameters at the times of periastron, the range of spin rates and phase angles for which an immediate resonance passage is triggered is very narrow, and yet a planet like Mercury rarely fails to align itself into this state of unstable equilibrium before it traverses 2:1 resonance.

Climate of an Earth-Like World with Changing Eccentricity

Science.gov (United States)

Kohler, Susanna

2017-02-01

Having a giant planet like Jupiter next door can really wreak havoc on your orbit! A new study examines what such a bad neighbor might mean for the long-term climate of an Earth-like planet.Influence of a Bad NeighborThe presence of a Jupiter-like giant planet in a nearby orbit can significantly affect how terrestrial planets evolve dynamically, causing elements like the planets orbital eccentricities and axial tilts to change over time. Earth is saved this inconvenience Jupiter isnt close enough to significantly influence us, and our large moon stabilizes our orbit against Jupiters tugs.Top panels: Authors simulationoutcomes for Case1, in which the planets eccentricity varies from 0 to 0.283 over 6500 years. Bottom panels: Outcomes for Case 2, in which the planets eccentricity varies from 0 to 0.066 over 4500 years. The highereccentricities reached in Case 1 causes the climate parameters to vary more widely. Click for a better look! [Way Georgakarakos 2017]Mars, on the other hand, isnt as lucky: its possible that Jupiters gravitational pull causes Marss axial tilt, for instance, to evolve through a range as large as 0 to 60 degrees on timescales of millions of years! Marss orbital eccentricity is similarly thought to vary due to Jupiters influence, and both of these factors play a major role in determining Marss climate.As exoplanet missions discover more planets many of which are Earth-like we must carefully consider which among these are most likely to be capable of sustaining life. If having a nearby neighbor like a Jupiter can tug an Earth-like world into an orbit with varying eccentricity, how does this affect the planets climate? Will the planet remain temperate? Or will it develop a runaway heating or cooling effect as it orbits, rendering it uninhabitable?Oceans and OrbitsTo examine these questions, two scientists have built the first ever 3D global climate model simulations of an Earth-like world using a fully coupled ocean (necessary for understanding

The Eccentric Kozai–Lidov Mechanism for Outer Test Particle

Energy Technology Data Exchange (ETDEWEB)

Naoz, Smadar [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States); Li, Gongjie [Harvard Smithsonian Center for Astrophysics, Institute for Theory and Computation, 60 Garden Street, Cambridge, MA 02138 (United States); Zanardi, Macarena; De Elía, Gonzalo Carlos; Di Sisto, Romina P., E-mail: snaoz@astro.ucla.edu [Instituto de Astrofísica de La Plata, CCT La Plata-CONICET-UNLP Paseo del Bosque S/N (1900), La Plata (Argentina)

2017-07-01

The secular approximation of the hierarchical three body systems has been proven to be very useful in addressing many astrophysical systems, from planets to stars to black holes. In such a system, two objects are on a tight orbit and the tertiary is on a much wider orbit. Here, we study the dynamics of a system by taking the tertiary mass to zero and solve the hierarchical three body system up to the octupole level of approximation. We find a rich dynamics that the outer orbit undergoes due to gravitational perturbations from the inner binary. The nominal result of the precession of the nodes is mostly limited for the lowest order of approximation; however, when the octupole level of approximation is introduced, the system becomes chaotic, as expected, and the tertiary oscillates below and above 90°, similarly to the non-test particle flip behavior. We provide the Hamiltonian of the system and investigate the dynamics of the system from the quadrupole to the octupole level of approximations. We also analyze the chaotic and quasi-periodic orbital evolution by studying the surfaces of sections. Furthermore, including general relativity, we showcase the long-term evolution of individual debris disk particles under the influence of a far-away interior eccentric planet. We show that this dynamics can naturally result in retrograde objects and a puffy disk after a long timescale evolution (a few Gyr) for initially aligned configuration.

The Eccentric Kozai-Lidov Mechanism for Outer Test Particle

Science.gov (United States)

Naoz, Smadar; Li, Gongjie; Zanardi, Macarena; de Elía, Gonzalo Carlos; Di Sisto, Romina P.

2017-07-01

The secular approximation of the hierarchical three body systems has been proven to be very useful in addressing many astrophysical systems, from planets to stars to black holes. In such a system, two objects are on a tight orbit and the tertiary is on a much wider orbit. Here, we study the dynamics of a system by taking the tertiary mass to zero and solve the hierarchical three body system up to the octupole level of approximation. We find a rich dynamics that the outer orbit undergoes due to gravitational perturbations from the inner binary. The nominal result of the precession of the nodes is mostly limited for the lowest order of approximation; however, when the octupole level of approximation is introduced, the system becomes chaotic, as expected, and the tertiary oscillates below and above 90°, similarly to the non-test particle flip behavior. We provide the Hamiltonian of the system and investigate the dynamics of the system from the quadrupole to the octupole level of approximations. We also analyze the chaotic and quasi-periodic orbital evolution by studying the surfaces of sections. Furthermore, including general relativity, we showcase the long-term evolution of individual debris disk particles under the influence of a far-away interior eccentric planet. We show that this dynamics can naturally result in retrograde objects and a puffy disk after a long timescale evolution (a few Gyr) for initially aligned configuration.

Frequency modulation reveals the phasing of orbital eccentricity during Cretaceous Oceanic Anoxic Event II and the Eocene hyperthermals

Science.gov (United States)

Laurin, Jiří; Meyers, Stephen R.; Galeotti, Simone; Lanci, Luca

2016-05-01

Major advances in our understanding of paleoclimate change derive from a precise reconstruction of the periods, amplitudes and phases of the 'Milankovitch cycles' of precession, obliquity and eccentricity. While numerous quantitative approaches exist for the identification of these astronomical cycles in stratigraphic data, limitations in radioisotopic dating, and instability of the theoretical astronomical solutions beyond ∼50 Myr ago, can challenge identification of the phase relationships needed to constrain climate response and anchor floating astrochronologies. Here we demonstrate that interference patterns accompanying frequency modulation (FM) of short eccentricity provide a robust basis for identifying the phase of long eccentricity forcing in stratigraphic data. One- and two-dimensional models of sedimentary distortion of the astronomical signal are used to evaluate the veracity of the FM method, and indicate that pristine eccentricity FM can be readily distinguished in paleo-records. Apart from paleoclimatic implications, the FM approach provides a quantitative technique for testing and calibrating theoretical astronomical solutions, and for refining chronologies for the deep past. We present two case studies that use the FM approach to evaluate major carbon-cycle perturbations of the Eocene and Late Cretaceous. Interference patterns in the short-eccentricity band reveal that Eocene hyperthermals ETM2 ('Elmo'), H2, I1 and ETM3 (X; ∼52-54 Myr ago) were associated with maxima in the 405-kyr cycle of orbital eccentricity. The same eccentricity configuration favored regional anoxic episodes in the Mediterranean during the Middle and Late Cenomanian (∼94.5-97 Myr ago). The initial phase of the global Oceanic Anoxic Event II (OAE II; ∼93.9-94.5 Myr ago) coincides with maximum and falling 405-kyr eccentricity, and the recovery phase occurs during minimum and rising 405-kyr eccentricity. On a Myr scale, the event overlaps with a node in eccentricity

Eccentric, nonspinning, inspiral, Gaussian-process merger approximant for the detection and characterization of eccentric binary black hole mergers

Science.gov (United States)

Huerta, E. A.; Moore, C. J.; Kumar, Prayush; George, Daniel; Chua, Alvin J. K.; Haas, Roland; Wessel, Erik; Johnson, Daniel; Glennon, Derek; Rebei, Adam; Holgado, A. Miguel; Gair, Jonathan R.; Pfeiffer, Harald P.

2018-01-01

We present ENIGMA, a time domain, inspiral-merger-ringdown waveform model that describes nonspinning binary black holes systems that evolve on moderately eccentric orbits. The inspiral evolution is described using a consistent combination of post-Newtonian theory, self-force and black hole perturbation theory. Assuming eccentric binaries that circularize prior to coalescence, we smoothly match the eccentric inspiral with a stand-alone, quasicircular merger, which is constructed using machine learning algorithms that are trained with quasicircular numerical relativity waveforms. We show that ENIGMA reproduces with excellent accuracy the dynamics of quasicircular compact binaries. We validate ENIGMA using a set of Einstein Toolkit eccentric numerical relativity waveforms, which describe eccentric binary black hole mergers with mass-ratios between 1 ≤q ≤5.5 , and eccentricities e0≲0.2 ten orbits before merger. We use this model to explore in detail the physics that can be extracted with moderately eccentric, nonspinning binary black hole mergers. In particular, we use ENIGMA to show that the gravitational wave transients GW150914, GW151226, GW170104, GW170814 and GW170608 can be effectively recovered with spinning, quasicircular templates if the eccentricity of these events at a gravitational wave frequency of 10 Hz satisfies e0≤{0.175 ,0.125 ,0.175 ,0.175 ,0.125 }, respectively. We show that if these systems have eccentricities e0˜0.1 at a gravitational wave frequency of 10 Hz, they can be misclassified as quasicircular binaries due to parameter space degeneracies between eccentricity and spin corrections. Using our catalog of eccentric numerical relativity simulations, we discuss the importance of including higher-order waveform multipoles in gravitational wave searches of eccentric binary black hole mergers.

Dynamical Analysis of the Circumprimary Planet in the Eccentric Binary System HD 59686

Science.gov (United States)

Trifonov, Trifon; Lee, Man Hoi; Reffert, Sabine; Quirrenbach, Andreas

2018-04-01

We present a detailed orbital and stability analysis of the HD 59686 binary-star planet system. HD 59686 is a single-lined, moderately close (a B = 13.6 au) eccentric (e B = 0.73) binary, where the primary is an evolved K giant with mass M = 1.9 M ⊙ and the secondary is a star with a minimum mass of m B = 0.53 M ⊙. Additionally, on the basis of precise radial velocity (RV) data, a Jovian planet with a minimum mass of m p = 7 M Jup, orbiting the primary on a nearly circular S-type orbit with e p = 0.05 and a p = 1.09 au, has recently been announced. We investigate large sets of orbital fits consistent with HD 59686's RV data by applying bootstrap and systematic grid search techniques coupled with self-consistent dynamical fitting. We perform long-term dynamical integrations of these fits to constrain the permitted orbital configurations. We find that if the binary and the planet in this system have prograde and aligned coplanar orbits, there are narrow regions of stable orbital solutions locked in a secular apsidal alignment with the angle between the periapses, Δω, librating about 0°. We also test a large number of mutually inclined dynamical models in an attempt to constrain the three-dimensional orbital architecture. We find that for nearly coplanar and retrograde orbits with mutual inclination 145° ≲ Δi ≤ 180°, the system is fully stable for a large range of orbital solutions.

The Carter constant for inclined orbits about a massive Kerr black hole: I. Circular orbits

Energy Technology Data Exchange (ETDEWEB)

Komorowski, P G; Valluri, S R; Houde, M, E-mail: pkomorow@uwo.c, E-mail: valluri@uwo.c, E-mail: mhoude2@uwo.c [Department of Physics and Astronomy, University of Western Ontario, London, Ontario (Canada)

2010-11-21

In an extreme binary black hole system, an orbit will increase its angle of inclination ({iota}) as it evolves in Kerr spacetime. We focus our attention on the behaviour of the Carter constant (Q) for near-polar orbits, and develop an analysis that is independent of and complements radiation-reaction models. For a Schwarzschild black hole, the polar orbits represent the abutment between the prograde and retrograde orbits at which Q is at its maximum value for given values of the latus rectum ({tilde l}) and the eccentricity (e). The introduction of spin ({tilde S}={vert_bar}J{vert_bar}/M{sup 2}) to the massive black hole causes this boundary, or abutment, to be moved towards greater orbital inclination; thus, it no longer cleanly separates prograde and retrograde orbits. To characterize the abutment of a Kerr black hole (KBH), we first investigated the last stable orbit (LSO) of a test-particle about a KBH, and then extended this work to general orbits. To develop a better understanding of the evolution of Q we developed analytical formulae for Q in terms of {tilde l}, e and {tilde S} to describe elliptical orbits at the abutment, polar orbits and LSOs. By knowing the analytical form of {partial_derivative}Q/{partial_derivative}{tilde l} at the abutment, we were able to test a 2PN flux equation for Q. We also used these formulae to numerically calculate the {partial_derivative}{iota}/{partial_derivative}{tilde l} of hypothetical circular orbits that evolve along the abutment. From these values we have determined that {partial_derivative}{iota}/{partial_derivative}{tilde l} = -(122.7{tilde S} - 36{tilde S}{sup 3}){tilde l}{sup -11/2} - (63/2 {tilde S} + 35/4 {tilde S}{sup 3}){tilde l}{sup -9/2} - 15/2 {tilde S}{tilde l}{sup -7/2} - 9/2 {tilde S}{tilde l}{sup -5/2}. By taking the limit of this equation for {tilde l} {yields} {infinity}, and comparing it with the published result for the weak-field radiation reaction, we found the upper limit on

Shedding light on the eccentricity valley: Gap heating and eccentricity excitation of giant planets in protoplanetary disks

International Nuclear Information System (INIS)

Tsang, David; Cumming, Andrew; Turner, Neal J.

2014-01-01

We show that the first order (non-co-orbital) corotation torques are significantly modified by entropy gradients in a non-barotropic protoplanetary disk. Such non-barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap-clearing planets embedded in the disk. We demonstrate that stellar illumination can heat the gap enough for the planet's orbital eccentricity to instead be excited. We also discuss the 'Eccentricity Valley' noted in the known exoplanet population, where low-metallicity stars have a deficit of eccentric planets between ∼0.1 and ∼1 AU compared to metal-rich systems. We show that this feature in the planet distribution may be due to the self-shadowing of the disk by a rim located at the dust sublimation radius ∼0.1 AU, which is known to exist for several T Tauri systems. In the shadowed region between ∼0.1 and ∼1 AU, lack of gap insolation allows disk interactions to damp eccentricity. Outside such shadowed regions stellar illumination can heat the planetary gaps and drive eccentricity growth for giant planets. We suggest that the self-shadowing does not arise at higher metallicity due to the increased optical depth of the gas interior to the dust sublimation radius.

Shedding light on the eccentricity valley: Gap heating and eccentricity excitation of giant planets in protoplanetary disks

Energy Technology Data Exchange (ETDEWEB)

Tsang, David; Cumming, Andrew [Department of Physics, McGill University, Montreal, QC H3A 2T8 (Canada); Turner, Neal J., E-mail: dtsang@physics.mcgill.ca [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States)

2014-02-20

We show that the first order (non-co-orbital) corotation torques are significantly modified by entropy gradients in a non-barotropic protoplanetary disk. Such non-barotropic torques can dramatically alter the balance that, for barotropic cases, results in the net eccentricity damping for giant gap-clearing planets embedded in the disk. We demonstrate that stellar illumination can heat the gap enough for the planet's orbital eccentricity to instead be excited. We also discuss the 'Eccentricity Valley' noted in the known exoplanet population, where low-metallicity stars have a deficit of eccentric planets between ∼0.1 and ∼1 AU compared to metal-rich systems. We show that this feature in the planet distribution may be due to the self-shadowing of the disk by a rim located at the dust sublimation radius ∼0.1 AU, which is known to exist for several T Tauri systems. In the shadowed region between ∼0.1 and ∼1 AU, lack of gap insolation allows disk interactions to damp eccentricity. Outside such shadowed regions stellar illumination can heat the planetary gaps and drive eccentricity growth for giant planets. We suggest that the self-shadowing does not arise at higher metallicity due to the increased optical depth of the gas interior to the dust sublimation radius.

Eccentric binaries of compact objects in strong-field gravity

International Nuclear Information System (INIS)

Gold, Roman

2011-01-01

In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on to the

Contraction of high eccentricity satellite orbits using uniformly regular KS canonical elements with oblate diurnally varying atmosphere.

Science.gov (United States)

Raj, Xavier James

2016-07-01

Accurate orbit prediction of an artificial satellite under the influence of air drag is one of the most difficult and untraceable problem in orbital dynamics. The orbital decay of these satellites is mainly controlled by the atmospheric drag effects. The effects of the atmosphere are difficult to determine, since the atmospheric density undergoes large fluctuations. The classical Newtonian equations of motion, which is non linear is not suitable for long-term integration. Many transformations have emerged in the literature to stabilize the equations of motion either to reduce the accumulation of local numerical errors or allowing the use of large integration step sizes, or both in the transformed space. One such transformation is known as KS transformation by Kustaanheimo and Stiefel, who regularized the nonlinear Kepler equations of motion and reduced it into linear differential equations of a harmonic oscillator of constant frequency. The method of KS total energy element equations has been found to be a very powerful method for obtaining numerical as well as analytical solution with respect to any type of perturbing forces, as the equations are less sensitive to round off and truncation errors. The uniformly regular KS canonical equations are a particular canonical form of the KS differential equations, where all the ten KS Canonical elements αi and βi are constant for unperturbed motion. These equations permit the uniform formulation of the basic laws of elliptic, parabolic and hyperbolic motion. Using these equations, developed analytical solution for short term orbit predictions with respect to Earth's zonal harmonic terms J2, J3, J4. Further, these equations were utilized to include the canonical forces and analytical theories with air drag were developed for low eccentricity orbits (e 0.2) orbits by assuming the atmosphere to be oblate only. In this paper a new non-singular analytical theory is developed for the motion of high eccentricity satellite

Development of a methodology for deriving Plasmaspheric Total Electron Content from In-Situ electron density measurements in highly eccentric equatorial orbits

Science.gov (United States)

Sadhique, Aliyuthuman; Buckley, Andrew; Gough, Paul; Sussex Space Science Centre Team

2017-10-01

The contribution of the Upper Plasmasphere (defined as the altitudes above semi-synchronous orbit height to the Plasmapause height) to the TEC has been and continues to be un-quantified. The PEACE instrument in the Chinese - ESA Double Star TC1 satellite, the mission's orbit's high eccentricity, low perigee, high apogee and the resulting smaller incident angle while in the above altitude range provide the ideal geometric opportunity to build a methodology and to utilize its empirical in-situ electron density measurements to determine the Upper Plasmaspheric TEC component. Furthermore, the variation of the Inclination Angle of TC1 makes it a suitable equatorial mission confined to the Near-Equatorial region, ie 200 - 250 on either sides of the magnetic equator. As the most pronounced absolute TEC values and variations are within this region, it offers an excellent opportunity to build a Upper Plasmaspheric TEC database. This research generates such, first-ever database along its orbital path, using a methodology of approximation equating arcs of the orbits to straight-line TEC Bars, utilizing complex mathematics, also enabling the determination of the whole Plasmaspheric TEC from any eccentric orbital probe. Presented the paper in 15th International Workshop on Technical and Scientific Aspects of MST radar (MST15/iMST2)'' and ``18th EISCAT Symposium (EISCAT18)'' in Tokyo, Japan and The Royal Astronomical Society National Astronomy Meeting 2017.

Mismatch analysis of humeral nailing. Antegrade versus retrograde insertion

International Nuclear Information System (INIS)

Mahaisavariya, B.; Jiamwatthanachai, P.; Aroonjarattham, P.; Aroonjarattham, K.; Wongcumchang, M.; Sitthiseripratip, K.

2011-01-01

Closed humeral nailing is now considered an alternative treatment for humeral-shaft fracture. The nail can be inserted with either the antegrade or retrograde method. We investigated and compared the problem of geometric mismatch of the humeral nail to the humerus between the two methods of insertion. The study was performed using virtual simulation based on computed tomography (CT) data of 76 Thai cadaveric humeri and the commonly used Russell-Taylor humeral nail 8 mm in diameter and 220 mm long. Mismatch of the nail to the intact humerus was analyzed and compared between the antegrade and retrograde nailing approaches. The results showed: the diameter of the medullary canal averaged 7.9-13.8 mm; the minimal reaming diameter to accommodate virtual nail insertion averaged 8.8-14.8 mm for the antegrade and 8.8-29.3 mm for the retrograde approach; the minimal reaming thickness of the inner cortex averaged 0.1-1.5 mm for the antegrade and 0.1-9.9 mm for the retrograde approach; the percentages of cortical bone removed prior to nail insertion were 3.8-107.1% and 3.8-1,287.6% for the antegrade and retrograde approaches, respectively; the eccentricity of the nail-medullary canal center were 0.4-3.4 and 0.4-10.6 mm for the antegrade and retrograde approaches, respectively. Less mismatching occurred with antegrade nailing than with the retrograde approach. Retrograde nailing requires excessive reaming at the distal part of the humerus to accommodate nail insertion. This may create bone weakness and the risk of supracondylar fracture. (author)

Frozen orbit realization using LQR analogy

Science.gov (United States)

Nagarajan, N.; Rayan, H. Reno

In the case of remote sensing orbits, the Frozen Orbit concept minimizes altitude variations over a given region using passive means. This is achieved by establishing the mean eccentricity vector at the orbital poles i.e., by fixing the mean argument of perigee at 90 deg with an appropriate eccentricity to balance the perturbations due to zonal harmonics J2 and J3 of the Earth's potential. Eccentricity vector is a vector whose magnitude is the eccentricity and direction is the argument of perigee. The launcher dispersions result in an eccentricity vector which is away from the frozen orbit values. The objective is then to formulate an orbit maneuver strategy to optimize the fuel required to achieve the frozen orbit in the presence of visibility and impulse constraints. It is shown that the motion of the eccentricity vector around the frozen perigee can be approximated as a circle. Combining the circular motion of the eccentricity vector around the frozen point and the maneuver equation, the following discrete equation is obtained. X(k+1) = AX(k) + Bu(k), where X is the state (i.e. eccentricity vector components), A the state transition matrix, u the scalar control force (i.e. dV in this case) and B the control matrix which transforms dV into eccentricity vector change. Based on this, it is shown that the problem of optimizing the fuel can be treated as a Linear Quadratic Regulator (LQR) problem in which the maneuver can be solved by using control system design tools like MATLAB by deriving an analogy LQR design.

Eccentric binaries of compact objects in strong-field gravity

Energy Technology Data Exchange (ETDEWEB)

Gold, Roman

2011-09-27

In this thesis we study the dynamics as well as the resulting gravitational radiation from eccentric binaries of compact objects in the non-linear regime of General Relativity. For this purpose we solve Einstein's field equation numerically in a 3+1 decomposition using the moving-puncture technique. We focus our study on very particular orbits, arising as a purely relativistic phenomenon of the two-body problem in General Relativity, which are associated with unstable circular orbits. They are governed by a fast, nearly circular revolution at a short distance followed by a slow, radial motion on a nearly elliptic trajectory. Due to the unique features of their orbital trajectories they are called zoom-whirl orbits. We analyze how the peculiar dynamics manifests itself in the emitted gravitational radiation and to which extent one can infer the orbital properties from observations of the gravitational waves. In the first part, we consider black hole binaries. We perform a comprehensive parameter study by varying the initial eccentricity, computing and characterizing the resulting gravitational waveforms. We address aspects, which can only be obtained from non-perturbative methods, and which are crucial to the astrophysical relevance of these orbits. In particular, our results imply a fairly low amount of fine-tuning necessary to spot zoom-whirl effects. We find whirl orbits for values of the eccentricities, which fall in disjunct intervals extending to rather low values. Furthermore, we show that whirl effects just before merger cause a signal with significant amplitude. In the second part, we investigate neutron star binaries on eccentric orbits in full General Relativity, which has not been studied so far. We explore their phenomenology and study the consequences for the matter after the neutron stars have merged. In these evolutions the merged neutron stars sooner or later collapse to form a black hole. During the collapse most of the matter is accreted on

RESONANT POST-NEWTONIAN ECCENTRICITY EXCITATION IN HIERARCHICAL THREE-BODY SYSTEMS

Energy Technology Data Exchange (ETDEWEB)

Naoz, Smadar; Kocsis, Bence; Loeb, Abraham [Institute for Theory and Computation, Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Yunes, Nicolas, E-mail: snaoz@cfa.harvard.edu [Department of Physics, Montana State University, Bozeman, MT 59718 (United States)

2013-08-20

We study the secular, hierarchical three-body problem to first-order in a post-Newtonian expansion of general relativity (GR). We expand the first-order post-Newtonian Hamiltonian to leading-order in the ratio of the semi-major axis of the two orbits. In addition to the well-known terms that correspond to the GR precession of the inner and outer orbits, we find a new secular post-Newtonian interaction term that can affect the long-term evolution of the triple. We explore the parameter space for highly inclined and eccentric systems, where the Kozai-Lidov mechanism can produce large-amplitude oscillations in the eccentricities. The standard lore, i.e., that GR effects suppress eccentricity, is only consistent with the parts of phase space where the GR timescales are several orders of magnitude shorter than the secular Newtonian one. In other parts of phase space, however, post-Newtonian corrections combined with the three-body ones can excite eccentricities. In particular, for systems where the GR timescale is comparable to the secular Newtonian timescales, the three-body interactions give rise to a resonant-like eccentricity excitation. Furthermore, for triples with a comparable-mass inner binary, where the eccentric Kozai-Lidov mechanism is suppressed, post-Newtonian corrections can further increase the eccentricity and lead to orbital flips even when the timescale of the former is much longer than the timescale of the secular Kozai-Lidov quadrupole perturbations.

ORBITAL DEPENDENCE OF GALAXY PROPERTIES IN SATELLITE SYSTEMS OF GALAXIES

International Nuclear Information System (INIS)

Hwang, Ho Seong; Park, Changbom

2010-01-01

We study the dependence of satellite galaxy properties on the distance to the host galaxy and the orbital motion (prograde and retrograde orbits) using the Sloan Digital Sky Survey (SDSS) data. From SDSS Data Release 7, we find 3515 isolated satellite systems of galaxies at z -1 . It is found that the radial distribution of early-type satellites in prograde orbit is strongly concentrated toward the host while that of retrograde ones shows much less concentration. We also find the orbital speed of late-type satellites in prograde orbit increases as the projected distance to the host (R) decreases while the speed decreases for those in retrograde orbit. At R less than 0.1 times the host virial radius (R vir,host ), the orbital speed decreases in both prograde and retrograde orbit cases. Prograde satellites are on average fainter than retrograde satellites for both early and late morphological types. The u - r color becomes redder as R decreases for both prograde and retrograde orbit late-type satellites. The differences between prograde and retrograde orbit satellite galaxies may be attributed to their different origin or the different strength of physical processes that they have experienced through hydrodynamic interactions with their host galaxies.

HABITABLE CLIMATES: THE INFLUENCE OF ECCENTRICITY

International Nuclear Information System (INIS)

Dressing, Courtney D.; Spiegel, David S.; Scharf, Caleb A.; Menou, Kristen; Raymond, Sean N.

2010-01-01

In the outer regions of the habitable zone, the risk of transitioning into a globally frozen 'snowball' state poses a threat to the habitability of planets with the capacity to host water-based life. Here, we use a one-dimensional energy balance climate model (EBM) to examine how obliquity, spin rate, orbital eccentricity, and the fraction of the surface covered by ocean might influence the onset of such a snowball state. For an exoplanet, these parameters may be strikingly different from the values observed for Earth. Since, for a constant semimajor axis, the annual mean stellar irradiation scales with (1 - e 2 ) -1/2 , one might expect the greatest habitable semimajor axis (for fixed atmospheric composition) to scale as (1 - e 2 ) -1/4 . We find that this standard simple ansatz provides a reasonable lower bound on the outer boundary of the habitable zone, but the influence of both obliquity and ocean fraction can be profound in the context of planets on eccentric orbits. For planets with eccentricity 0.5, for instance, our EBM suggests that the greatest habitable semimajor axis can vary by more than 0.8 AU (78%!) depending on obliquity, with higher obliquity worlds generally more stable against snowball transitions. One might also expect that the long winter at an eccentric planet's apoastron would render it more susceptible to global freezing. Our models suggest that this is not a significant risk for Earth-like planets around Sun-like stars, as considered here, since such planets are buffered by the thermal inertia provided by oceans covering at least 10% of their surface. Since planets on eccentric orbits spend much of their year particularly far from the star, such worlds might turnout to be especially good targets for direct observations with missions such as TPF-Darwin. Nevertheless, the extreme temperature variations achieved on highly eccentric exo-Earths raise questions about the adaptability of life to marginally or transiently habitable conditions.

Tidal Disruption Events from Eccentric Nuclear Disks

Science.gov (United States)

Wernke, Heather N.; Madigan, Ann-Marie

2018-04-01

Stars that get too close to a supermassive black hole are in danger of being tidally disrupted. Stellar two-body relaxation is commonly assumed to be the main driver of these events. Recent work has shown, however, that secular gravitational torques from eccentric nuclear disks can push stars to extreme eccentricities at much higher rates than predicted by two-body relaxation. This work did not include the effects of general relativity, however, which could quench secular torques via rapid apsidal precession. Here we show that, for a star in danger of disruption, general relativity acts on a timescale of less than an orbital period. This short timescale means that general relativity does not have enough time to have a major effect on the orbit. When driven by secular torques from eccentric nuclear disks, tidal disruption event rates are not affected by general relativity.

A Comprehensive Catalog of Galactic Eclipsing Binary Stars with Eccentric Orbits Based on Eclipse Timing Diagrams

Science.gov (United States)

Kim, C.-H.; Kreiner, J. M.; Zakrzewski, B.; Ogłoza, W.; Kim, H.-W.; Jeong, M.-J.

2018-04-01

A comprehensive catalog of 623 galactic eclipsing binary (EB) systems with eccentric orbits is presented with more than 2830 times of minima determined from the archived photometric data by various sky-survey projects and new photometric measurements. The systems are divided into two groups according to whether the individual system has a GCVS name or not. All the systems in both groups are further classified into three categories (D, A, and A+III) on the basis of their eclipse timing diagrams: 453 D systems showing just constantly displaced secondary minima, 139 A systems displaying only apsidal motion (AM), and 31 A+III systems exhibiting both AM and light-time effects. AM parameters for 170 systems (A and A+III systems) are consistently calculated and cataloged with basic information for all systems. Some important statistics for the AM parameters are discussed and compared with those derived for the eccentric EB systems in the Large and Small Magellanic Clouds.

A Complete First-Order Analytical Solution for Optimal Low-Thrust Limited-Power Transfers Between Coplanar Orbits with Small Eccentricities

Science.gov (United States)

Da Silva Fernandes, Sandro; Das Chagas Carvalho, Francisco; Vilhena de Moraes, Rodolpho

The purpose of this work is to present a complete first order analytical solution, which includes short periodic terms, for the problem of optimal low-thrust limited power trajectories with large amplitude transfers (no rendezvous) between coplanar orbits with small eccentricities in Newtonian central gravity field. The study of these transfers is particularly interesting because the orbits found in practice often have a small eccentricity and the problem of transferring a vehicle from a low earth orbit to a high earth orbit is frequently found. Besides, the analysis has been motivated by the renewed interest in the use of low-thrust propulsion systems in space missions verified in the last two decades. Several researchers have obtained numerical and sometimes analytical solutions for a number of specific initial orbits and specific thrust profiles. Averaging methods are also used in such researches. Firstly, the optimization problem associated to the space transfer problem is formulated as a Mayer problem of optimal control with Cartesian elements - position and velocity vectors - as state variables. After applying the Pontryagin Maximum Principle, successive Mathieu transformations are performed and suitable sets of orbital elements are introduced. The short periodic terms are eliminated from the maximum Hamiltonian function through an infinitesimal canonical transformation built through Hori method - a perturbation canonical method based on Lie series. The new Hamiltonian function, which results from the infinitesimal canonical transformation, describes the extremal trajectories for long duration maneuvers. Closed-form analytical solutions are obtained for the new canonical system by solving the Hamilton-Jacobi equation through the separation of variables technique. By applying the transformation equations of the algorithm of Hori method, a first order analytical solution for the problem is obtained in non-singular orbital elements. For long duration maneuvers

Detection and Characterization of Extrasolar Planets through Mean-motion Resonances. II. The Effect of the Planet’s Orbital Eccentricity on Debris Disk Structures

Energy Technology Data Exchange (ETDEWEB)

Tabeshian, Maryam; Wiegert, Paul A., E-mail: mtabeshi@uwo.ca [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada)

2017-09-20

Structures observed in debris disks may be caused by gravitational interaction with planetary or stellar companions. These perturbed disks are often thought to indicate the presence of planets and offer insights into the properties of both the disk and the perturbing planets. Gaps in debris disks may indicate a planet physically present within the gap, but such gaps can also occur away from the planet’s orbit at mean-motion resonances (MMRs), and this is the focus of our interest here. We extend our study of planet–disk interaction through MMRs, presented in an earlier paper, to systems in which the perturbing planet has moderate orbital eccentricity, a common occurrence in exoplanetary systems. In particular, a new result is that the 3:1 MMR becomes distinct at higher eccentricity, while its effects are absent for circular planetary orbits. We also only consider gravitational interaction with a planetary body of at least 1 M {sub J}. Our earlier work shows that even a 1 Earth mass planet can theoretically open an MMR gap; however, given the narrow gap that can be opened by a low-mass planet, its observability would be questionable. We find that the widths, locations, and shapes of two prominent structures, the 2:1 and 3:1 MMRs, could be used to determine the mass, semimajor axis, and eccentricity of the planetary perturber and present an algorithm for doing so. These MMR structures can be used to narrow the position and even determine the planetary properties (such as mass) of any inferred but as-yet-unseen planets within a debris disk. We also briefly discuss the implications of eccentric disks on brightness asymmetries and their dependence on the wavelengths with which these disks are observed.

HAT-P-13b,c: A TRANSITING HOT JUPITER WITH A MASSIVE OUTER COMPANION ON AN ECCENTRIC ORBIT

International Nuclear Information System (INIS)

Bakos, G. A.; Noyes, R. W.; Hartman, J.; Torres, G.; Latham, D. W.; Sasselov, D. D.; Stefanik, R. P.; Sipocz, B.; Kovacs, Gabor; Esquerdo, G. A.; Pal, A.; Howard, A. W.; Marcy, G. W.; Kovacs, Geza; Fischer, D. A.; Johnson, J. A.; Lazar, J.; Papp, I.; Sari, P.

2009-01-01

We report on the discovery of a planetary system with a close-in transiting hot Jupiter on a near circular orbit and a massive outer planet on a highly eccentric orbit. The inner planet, HAT-P-13b, transits the bright V = 10.622 G4 dwarf star GSC 3416 - 00543 every P = 2.916260 ± 0.000010 days, with transit epoch T c = 2454779.92979 ± 0.00038 (BJD) and duration 0.1345 ± 0.0017 days. The outer planet HAT-P-13c orbits the star every P 2 = 428.5 ± 3.0 days with a nominal transit center (assuming zero impact parameter) of T 2c = 2454870.4 ± 1.8 (BJD) or time of periastron passage T 2,peri = 2454890.05 ± 0.48 (BJD). Transits of the outer planet have not been observed, and may not be present. The host star has a mass of 1.22 +0.05 -0.10 M sun , radius of 1.56 ± 0.08 R sun , effective temperature of 5653 ± 90 K, and is rather metal-rich with [Fe/H] = +0.41 ± 0.08. The inner planetary companion has a mass of 0.853 +0.029 -0.046 M J , and radius of 1.281 ± 0.079 R J , yielding a mean density of 0.498 +0.103 -0.069 g cm -3 . The outer companion has m 2 sin i 2 = 15.2 ± 1.0 M J , and orbits on a highly eccentric orbit of e 2 = 0.691 ± 0.018. While we have not detected significant transit timing variations of HAT-P-13b, due to gravitational and light-travel time effects, future observations will constrain the orbital inclination of HAT-P-13c, along with its mutual inclination to HAT-P-13b. The HAT-P-13 (b, c) double-planet system may prove extremely valuable for theoretical studies of the formation and dynamics of planetary systems.

The Eccentric Satellites Problem: Comparing Milky Way Satellite Orbital Properties to Simulation Results

Science.gov (United States)

Haji, Umran; Pryor, Carlton; Applebaum, Elaad; Brooks, Alyson

2018-01-01

We compare the orbital properties of the satellite galaxies of the Milky Way to those of satellites found in simulated Milky Way-like systems as a means of testing cosmological simulations of galaxy formation. The particular problem that we are investigating is a discrepancy in the distribution of orbital eccentricities. Previous studies of Milky Way-mass systems analyzed in a semi-analytic ΛCDM cosmological model have found that the satellites tend to have significantly larger fractions of their kinetic energy invested in radial motion with respect to their central galaxy than do the real-world Milky Way satellites. We analyze several high-resolution ("zoom-in") hydrodynamical simulations of Milky Way-mass galaxies and their associated satellite systems to investigate why previous works found Milky Way-like systems to be rare. We find a possible relationship between a quiescent galactic assembly history and a distribution of satellite kinematics resembling that of the Milky Way. This project has been supported by funding from National Science Foundation grant PHY-1560077.

Contingency Trajectory Design for a Lunar Orbit Insertion Maneuver Failure by the LADEE Spacecraft

Science.gov (United States)

Genova, A. L.

2014-01-01

This paper presents results from a contingency trajectory analysis performed for the Lunar Atmosphere & Dust Environment Explorer (LADEE) mission in the event of a missed lunar-orbit insertion (LOI) maneuver by the LADEE spacecraft. The effects of varying solar perturbations in the vicinity of the weak stability boundary (WSB) in the Sun-Earth system on the trajectory design are analyzed and discussed. It is shown that geocentric recovery trajectory options existed for the LADEE spacecraft, depending on the spacecraft's recovery time to perform an Earth escape-prevention maneuver after the hypothetical LOI maneuver failure and subsequent path traveled through the Sun-Earth WSB. If Earth-escape occurred, a heliocentric recovery option existed, but with reduced science capacapability for the spacecraft in an eccentric, not circular near-equatorial retrograde lunar orbit.

Dynamical tides in highly eccentric binaries: chaos, dissipation, and quasi-steady state

Science.gov (United States)

Vick, Michelle; Lai, Dong

2018-05-01

Highly eccentric binary systems appear in many astrophysical contexts, ranging from tidal capture in dense star clusters, precursors of stellar disruption by massive black holes, to high-eccentricity migration of giant planets. In a highly eccentric binary, the tidal potential of one body can excite oscillatory modes in the other during a pericentre passage, resulting in energy exchange between the modes and the binary orbit. These modes exhibit one of three behaviours over multiple passages: low-amplitude oscillations, large-amplitude oscillations corresponding to a resonance between the orbital frequency and the mode frequency, and chaotic growth, with the mode energy reaching a level comparable to the orbital binding energy. We study these phenomena with an iterative map that includes mode dissipation, fully exploring how the mode evolution depends on the orbital and mode properties of the system. The dissipation of mode energy drives the system towards a quasi-steady state, with gradual orbital decay punctuated by resonances. We quantify the quasi-steady state and the long-term evolution of the system. A newly captured star around a black hole can experience significant orbital decay and heating due to the chaotic growth of the mode amplitude and dissipation. A giant planet pushed into a high-eccentricity orbit may experience a similar effect and become a hot or warm Jupiter.

Hereditary effects in eccentric compact binary inspirals to third post-Newtonian order

Science.gov (United States)

Loutrel, Nicholas; Yunes, Nicolás

2017-02-01

While there has been much success in understanding the orbital dynamics and gravitational wave emission of eccentric compact binaries in the post-Newtonian formalism, some problems still remain. The largest of these concerns hereditary effects: non-linear phenomena related to the scattering off of the background curved spacetime (tails) and to the generation of gravitational waves by gravitational waves (memory). Currently, these hereditary effects are only known numerically for arbitrary eccentricity through infinite sums of Bessel functions, with closed-form, analytic results only available in the small eccentricity limit. We here calculate, for the first time, closed-form, analytic expressions for all hereditary effects to third post-Newtonian order in binaries with arbitrary eccentricity. For the tails, we first asymptotically expand all Bessel functions in high eccentricity and find a superasymptotic series for each enhancement factor, accurate to better than 10-3 relative to post-Newtonian numerical calculations at all eccentricities. We further improve the small-eccentricity behavior of the superasymptotic series by generating hyperasymptotic expressions for each enhancement factor, typically accurate to better than 10-8 at all eccentricities. For the memory, we discuss its computation within the context of an osculating approximation of the binary’s orbit and the difficulties that arise. Our closed-form analytic expressions for the hereditary fluxes allow us to numerically compute orbital phases that are identical to those found using an infinite sum of Bessel functions to double numerical precision.

Hereditary effects in eccentric compact binary inspirals to third post-Newtonian order

International Nuclear Information System (INIS)

Loutrel, Nicholas; Yunes, Nicolás

2017-01-01

While there has been much success in understanding the orbital dynamics and gravitational wave emission of eccentric compact binaries in the post-Newtonian formalism, some problems still remain. The largest of these concerns hereditary effects: non-linear phenomena related to the scattering off of the background curved spacetime (tails) and to the generation of gravitational waves by gravitational waves (memory). Currently, these hereditary effects are only known numerically for arbitrary eccentricity through infinite sums of Bessel functions, with closed-form, analytic results only available in the small eccentricity limit. We here calculate, for the first time, closed-form, analytic expressions for all hereditary effects to third post-Newtonian order in binaries with arbitrary eccentricity. For the tails, we first asymptotically expand all Bessel functions in high eccentricity and find a superasymptotic series for each enhancement factor, accurate to better than 10 −3 relative to post-Newtonian numerical calculations at all eccentricities. We further improve the small-eccentricity behavior of the superasymptotic series by generating hyperasymptotic expressions for each enhancement factor, typically accurate to better than 10 −8 at all eccentricities. For the memory, we discuss its computation within the context of an osculating approximation of the binary’s orbit and the difficulties that arise. Our closed-form analytic expressions for the hereditary fluxes allow us to numerically compute orbital phases that are identical to those found using an infinite sum of Bessel functions to double numerical precision. (paper)

Accuracy of Estimating Highly Eccentric Binary Black Hole Parameters with Gravitational-wave Detections

Science.gov (United States)

Gondán, László; Kocsis, Bence; Raffai, Péter; Frei, Zsolt

2018-03-01

Mergers of stellar-mass black holes on highly eccentric orbits are among the targets for ground-based gravitational-wave detectors, including LIGO, VIRGO, and KAGRA. These sources may commonly form through gravitational-wave emission in high-velocity dispersion systems or through the secular Kozai–Lidov mechanism in triple systems. Gravitational waves carry information about the binaries’ orbital parameters and source location. Using the Fisher matrix technique, we determine the measurement accuracy with which the LIGO–VIRGO–KAGRA network could measure the source parameters of eccentric binaries using a matched filtering search of the repeated burst and eccentric inspiral phases of the waveform. We account for general relativistic precession and the evolution of the orbital eccentricity and frequency during the inspiral. We find that the signal-to-noise ratio and the parameter measurement accuracy may be significantly higher for eccentric sources than for circular sources. This increase is sensitive to the initial pericenter distance, the initial eccentricity, and the component masses. For instance, compared to a 30 {M}ȯ –30 {M}ȯ non-spinning circular binary, the chirp mass and sky-localization accuracy can improve by a factor of ∼129 (38) and ∼2 (11) for an initially highly eccentric binary assuming an initial pericenter distance of 20 M tot (10 M tot).

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

International Nuclear Information System (INIS)

Wit, Julien de; Lewis, Nikole K.; Knutson, Heather A.; Batygin, Konstantin; Fuller, Jim; Antoci, Victoria; Fulton, Benjamin J.; Laughlin, Gregory; Deming, Drake; Shporer, Avi; Cowan, Nicolas B.; Agol, Eric; Burrows, Adam S.; Fortney, Jonathan J.; Langton, Jonathan; Showman, Adam P.

2017-01-01

Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μ m observations with the Spitzer Space Telescope . The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μ m photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

The first retrograde Trojan asteroid

Science.gov (United States)

Wiegert, Paul; Connors, Martin; Veillet, Christian

2018-04-01

There are about six thousand asteroids which share Jupiter's orbit around the Sun. Called the 'Trojan asteroids', they co-exist easily with this giant planet because they travel in the same direction as it ('direct' or 'prograde' motion), and remain roughly 60 degrees ahead of or behind it in its orbit. Newly discovered asteroid 2015 BZ509 is on a retrograde orbit, but is nonetheless in a state dynamically analogous to that of the prograde Trojans. The discovery circumstances and the nature of the motion of this curious asteroid -the first of its kind- will be outlined.

Planet-induced Stellar Pulsations in HAT-P-2's Eccentric System

Energy Technology Data Exchange (ETDEWEB)

Wit, Julien de [Department of Earth, Atmospheric and Planetary Sciences, MIT, 77 Massachusetts Avenue, Cambridge, MA 02139 (United States); Lewis, Nikole K. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Knutson, Heather A.; Batygin, Konstantin [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Fuller, Jim [TAPIR, Walter Burke Institute for Theoretical Physics, Mailcode 350-17, California Institute of Technology, Pasadena, CA 91125 (United States); Antoci, Victoria [Stellar Astrophysics Centre, Department of Physics and Astronomy, Aarhus University, Ny Munkegade 120, DK-8000 Aarhus C (Denmark); Fulton, Benjamin J. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Laughlin, Gregory [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Deming, Drake [Department of Astronomy, University of Maryland at College Park, College Park, MD 20742 (United States); Shporer, Avi [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91009 (United States); Cowan, Nicolas B. [Department of Physics, Department of Earth and Planetary Sciences, McGill University, 3550 rue University, Montreal, QC H3A 2A7 (Canada); Agol, Eric [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Burrows, Adam S. [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Fortney, Jonathan J. [Department of Astronomy and Astrophysics, University of California, Santa Cruz, CA 95064 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Showman, Adam P. [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2017-02-20

Extrasolar planets on eccentric short-period orbits provide a laboratory in which to study radiative and tidal interactions between a planet and its host star under extreme forcing conditions. Studying such systems probes how the planet’s atmosphere redistributes the time-varying heat flux from its host and how the host star responds to transient tidal distortion. Here, we report the insights into the planet–star interactions in HAT-P-2's eccentric planetary system gained from the analysis of ∼350 hr of 4.5 μ m observations with the Spitzer Space Telescope . The observations show no sign of orbit-to-orbit variability nor of orbital evolution of the eccentric planetary companion, HAT-P-2 b. The extensive coverage allows us to better differentiate instrumental systematics from the transient heating of HAT-P-2 b’s 4.5 μ m photosphere and yields the detection of stellar pulsations with an amplitude of approximately 40 ppm. These pulsation modes correspond to exact harmonics of the planet’s orbital frequency, indicative of a tidal origin. Transient tidal effects can excite pulsation modes in the envelope of a star, but, to date, such pulsations had only been detected in highly eccentric stellar binaries. Current stellar models are unable to reproduce HAT-P-2's pulsations, suggesting that our understanding of the interactions at play in this system is incomplete.

Mesozoic cyclostratigraphy, the 405-kyr orbital eccentricity metronome, and the Astronomical Time Scale (Invited)

Science.gov (United States)

Hinnov, L.; Ogg, J. G.

2009-12-01

Mesozoic cyclostratigraphy from around the world is being assessed to construct a continuous Astronomical Time Scale (ATS) based on Earth’s cyclic orbital parameters. The recognition of a prevalent sedimentary cycling with a ~400-kyr period associated with forcing by the stable 405-kyr orbital eccentricity variation is an important development. Numerous formations spanning 10 to 20 myr (and longer) intervals in the Cretaceous, Jurassic and Triassic clearly express this dominant cycle and provide a robust basis for 405-kyr-scale calibration of the ATS. This 405-kyr metronome will enable extension of the well-defined Cenozoic ATS for scaling of the past quarter-billion years of Earth history. This astronomical calibration has a resolution comparable to the 1% to 0.1% precision for radioisotope dating of Mesozoic ash beds, with the added benefit of providing continuous stratigraphic coverage between dated beds. Extended portions of the Mesozoic ATS have already provided new insights into long-standing geologic problems of seafloor spreading, tectonics, eustasy, and paleoclimate change. Ongoing work is focused on closing gaps in coverage and on collecting duplicate cyclostratigraphic records for the entire Mesozoic Era.

AN ORBIT FIT FOR THE GRILLMAIR DIONATOS COLD STELLAR STREAM

International Nuclear Information System (INIS)

Willett, Benjamin A.; Newberg, Heidi Jo; Zhang Haotong; Yanny, Brian; Beers, Timothy C.

2009-01-01

We use velocity and metallicity information from Sloan Digital Sky Survey and Sloan Extension for Galactic Understanding and Exploration stellar spectroscopy to fit an orbit to the narrow 63 deg. stellar stream of Grillmair and Dionatos. The stars in the stream have a retrograde orbit with eccentricity e = 0.33 (perigalacticon of 14.4 kpc and apogalacticon of 28.7 kpc) and inclination approximately i ∼ 35 deg. In the region of the orbit which is detected, it has a distance of about 7-11 kpc from the Sun. Assuming a standard disk plus bulge and logarithmic halo potential for the Milky Way stars plus dark matter, the stream stars are moving with a large space velocity of approximately 276 km s -1 at perigalacticon. Using this stream alone, we are unable to determine if the dark matter halo is oblate or prolate. The metallicity of the stream is [Fe/H] = -2.1 ± 0.1. Observed proper motions for individual stream members above the main sequence turnoff are consistent with the derived orbit. None of the known globular clusters in the Milky Way have positions, radial velocities, and metallicities that are consistent with being the progenitor of the GD-1 stream.

An Orbit Fit for the Grillmair Dionatos Cold Stellar Stream

Energy Technology Data Exchange (ETDEWEB)

Willett, Benjamin A.; Newberg, Heidi Jo; Zhang, Haotong; Yanny, Brian; Beers, Timothy C.

2009-01-01

We use velocity and metallicity information from Sloan Digital Sky Survey and Sloan Extension for Galactic Understanding and Exploration stellar spectroscopy to fit an orbit to the narrow 63{sup o} stellar stream of Grillmair and Dionatos. The stars in the stream have a retrograde orbit with eccentricity e = 0.33 (perigalacticon of 14.4 kpc and apogalacticon of 28.7 kpc) and inclination approximately i {approx} 35{sup o}. In the region of the orbit which is detected, it has a distance of about 7-11 kpc from the Sun. Assuming a standard disk plus bulge and logarithmic halo potential for the Milky Way stars plus dark matter, the stream stars are moving with a large space velocity of approximately 276 km s{sup -1} at perigalacticon. Using this stream alone, we are unable to determine if the dark matter halo is oblate or prolate. The metallicity of the stream is [Fe/H] = -2.1 {+-} 0.1. Observed proper motions for individual stream members above the main sequence turnoff are consistent with the derived orbit. None of the known globular clusters in the Milky Way have positions, radial velocities, and metallicities that are consistent with being the progenitor of the GD-1 stream.

Explanation of the anomalous secular increase of the moon orbit eccentricity by the new theory of gravitation (NTG)

Science.gov (United States)

Ziefle, Reiner Georg

2013-03-01

Present day gravitational physics experiences a huge success in obtaining better and better experimental results. In some cases, the observations do not fit with the present knowledge of established physics. Phenomena, like the increase of the Astronomical Unit by 7 m per century or the so-called anomalous secular increase of the eccentricity of the lunar orbit by about 9 × 10^-12 per year, which can neither be explained by Einstein's Theory of General Relativity, nor by the Newtonian Theory of Gravitation, can be explained by the New Theory of Gravitation

The gravitational-wave memory from eccentric binaries

International Nuclear Information System (INIS)

Favata, Marc

2011-01-01

The nonlinear gravitational-wave memory causes a time-varying but nonoscillatory correction to the gravitational-wave polarizations. It arises from gravitational-waves that are sourced by gravitational-waves. Previous considerations of the nonlinear memory effect have focused on quasicircular binaries. Here I consider the nonlinear memory from Newtonian orbits with arbitrary eccentricity. Expressions for the waveform polarizations and spin-weighted spherical-harmonic modes are derived for elliptic, hyperbolic, parabolic, and radial orbits. In the hyperbolic, parabolic, and radial cases the nonlinear memory provides a 2.5 post-Newtonian (PN) correction to the leading-order waveforms. This is in contrast to the elliptical and quasicircular cases, where the nonlinear memory corrects the waveform at leading (0PN) order. This difference in PN order arises from the fact that the memory builds up over a short ''scattering'' time scale in the hyperbolic case, as opposed to a much longer radiation-reaction time scale in the elliptical case. The nonlinear memory corrections presented here complete our knowledge of the leading-order (Peters-Mathews) waveforms for elliptical orbits. These calculations are also relevant for binaries with quasicircular orbits in the present epoch which had, in the past, large eccentricities. Because the nonlinear memory depends sensitively on the past evolution of a binary, I discuss the effect of this early-time eccentricity on the value of the late-time memory in nearly circularized binaries. I also discuss the observability of large ''memory jumps'' in a binary's past that could arise from its formation in a capture process. Lastly, I provide estimates of the signal-to-noise ratio of the linear and nonlinear memories from hyperbolic and parabolic binaries.

Spin-orbit evolution of Mercury revisited

Science.gov (United States)

Noyelles, Benoît; Frouard, Julien; Makarov, Valeri V.; Efroimsky, Michael

2014-10-01

Although it is accepted that the significant eccentricity of Mercury (0.206) favours entrapment into the 3:2 spin-orbit resonance, open are the questions of how and when the capture took place. A recent work by Makarov (Makarov, V.V. [2012]. Astrophys. J., 752, 73) has proven that trapping into this state is certain for eccentricities larger than 0.2, provided we use a realistic tidal model based on the Darwin-Kaula expansion of the tidal torque. While in Ibid. a Mercury-like planet had its eccentricity fixed, we take into account its evolution. To that end, a family of possible histories of the eccentricity is generated, based on synthetic time evolution consistent with the expected statistics of the distribution of eccentricity. We employ a model of tidal friction, which takes into account both the rheology and self-gravitation of the planet. As opposed to the commonly used constant time lag (CTL) and constant phase lag (CPL) models, the physics-based tidal model changes dramatically the statistics of the possible final spin states. First, we discover that after only one encounter with the spin-orbit 3:2 resonance this resonance becomes the most probable end-state. Second, if a capture into this (or any other) resonance takes place, the capture becomes final, several crossings of the same state being forbidden by our model. Third, within our model the trapping of Mercury happens much faster than previously believed: for most histories, 10-20 Myr are sufficient. Fourth, even a weak laminar friction between the solid mantle and a molten core would most likely result in a capture in the 2:1 or even higher resonance, which is confirmed both semi-analytically and by limited numerical simulations. So the principal novelty of our paper is that the 3:2 end-state is more ancient than the same end-state obtained when the constant time lag model is employed. The swift capture justifies our treatment of Mercury as a homogeneous, unstratified body whose liquid core had not

A STRANGE STAR SCENARIO FOR THE FORMATION OF ECCENTRIC MILLISECOND PULSAR/HELIUM WHITE DWARF BINARIES

Energy Technology Data Exchange (ETDEWEB)

Jiang, Long; Li, Xiang-Dong [Department of Astronomy, Nanjing University, Nanjing 210046 (China); Dey, Jishnu; Dey, Mira, E-mail: lixd@nju.edu.cn [Department of Physics, Presidency University, 86/1, College Street, Kolkata 700 073 (India)

2015-07-01

According to the recycling scenario, millisecond pulsars (MSPs) have evolved from low-mass X-ray binaries (LMXBs). Their orbits are expected to be circular due to tidal interactions during binary evolution, as observed in most binary MSPs. There are some peculiar systems that do not fit this picture. Three recent examples are the PSRs J2234+06, J1946+3417, and J1950+2414, all of which are MSPs in eccentric orbits but with mass functions compatible with expected He white dwarf (WD) companions. It has been suggested these MSPs may have formed from delayed accretion-induced collapse of massive WDs, or the eccentricity may be induced by dynamical interaction between the binary and a circumbinary disk. Assuming that the core density of accreting neutron stars (NSs) in LMXBs may reach the density of quark deconfinement, which can lead to phase transition from NSs to strange quark stars, we show that the resultant MSPs are likely to have an eccentric orbit, due to the sudden loss of the gravitational mass of the NS during the transition. The eccentricities can be reproduced with a reasonable estimate of the mass loss. This scenario might also account for the formation of the youngest known X-ray binary Cir X–1, which also possesses a low-field compact star in an eccentric orbit.

Can Eccentric Debris Disks Be Long-lived? A First Numerical Investigation and Application to Zeta(exp 2) Reticuli

Science.gov (United States)

Faramaz, V.; Beust, H.; Thebault, P.; Augereau, J.-C.; Bonsor, A.; delBurgo, C.; Ertel, S.; Marshall, J. P.; Milli, J.; Montesinos, B.;

Deadly Sunflower Orbits

Science.gov (United States)

Hamilton, Douglas P.

2018-04-01

Solar radiation pressure is usually very effective at removing hazardous millimeter-sized debris from distant orbits around asteroidsand other small solar system bodies (Hamilton and Burns 1992). Theprimary loss mechanism, driven by the azimuthal component of radiationpressure, is eccentricity growth followed by a forced collision withthe central body. One large class of orbits, however, neatly sidestepsthis fate. Orbits oriented nearly perpendicular to the solar directioncan maintain their face-on geometry, oscillating slowly around a stableequilibrium orbit. These orbits, designated sunflower orbits, arerelated to terminator orbits studied by spacecraft mission designers(Broschart etal. 2014).Destabilization of sunflower orbits occurs only for particles smallenough that radiation pressure is some tens of percent the strength ofthe central body's direct gravity. This greatly enhanced stability,which follows from the inability of radiation incident normal to theorbit to efficiently drive eccentricities, presents a threat tospacecraft missions, as numerous dangerous projectiles are potentiallyretained in orbit. We have investigated sunflower orbits insupport of the New Horizons, Aida, and Lucy missions and find thatthese orbits are stable for hazardous particle sizes at asteroids,comets, and Kuiper belt objects of differing dimensions. Weinvestigate the sources and sinks for debris that might populate suchorbits, estimate timescales and equilibrium populations, and willreport on our findings.

Gravitational waves from spinning eccentric binaries

Science.gov (United States)

Csizmadia, Péter; Debreczeni, Gergely; Rácz, István; Vasúth, Mátyás

2012-12-01

This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations, while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems, it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity, thus confirming a similar result obtained by Brown and Zimmerman (2010 Phys. Rev. D 81 024007). In addition, by investigating the validity of the energy balance relation we show that, contrary to the general expectations, the PN approximation should not be applied once the PN parameter gets beyond the critical value ˜0.08 - 0.1. Finally, by studying the early phase of the gravitational waves emitted by strongly eccentric binary systems—which could be formed e.g. in various many-body interactions in the galactic halo—we have found that they possess very specific characteristics which may be used to identify these type of binary systems. This paper is dedicated to the memory of our colleague and friend Péter Csizmadia a young physicist, computer expert and one of the best Hungarian mountaineers who disappeared in China’s Sichuan near the Ren Zhong Feng peak of the Himalayas on 23 Oct. 2009. We started to develop CBwaves jointly with Péter a couple of months before he left for China.

Orbital tidal variability in the eccentric early type binary Iota Orionis

International Nuclear Information System (INIS)

Stevens, I.R.

1988-01-01

Iota Orionis is a bright, highly eccentric, massive early type binary, which has been studied recently in UV wavelengths, for evidence of stellar wind variability caused by tidal interactions between the two stars. No gross variability was found, but small scale perturbations in the UV resonance line profiles were noted. Here, using a radiatively driven stellar wind model for eccentric binaries, the results of numerical modelling of the stellar wind of Iota Orionis are presented. These calculations suggest that increased mass-loss from the primary star will occur close to the periastron passage, but that the enhancements will be short lived, and observed probably as redshifted emission features. (author)

NUMERICAL SIMULATIONS OF NATURALLY TILTED, RETROGRADELY PRECESSING, NODAL SUPERHUMPING ACCRETION DISKS

International Nuclear Information System (INIS)

Montgomery, M. M.

2012-01-01

Accretion disks around black hole, neutron star, and white dwarf systems are thought to sometimes tilt, retrogradely precess, and produce hump-shaped modulations in light curves that have a period shorter than the orbital period. Although artificially rotating numerically simulated accretion disks out of the orbital plane and around the line of nodes generate these short-period superhumps and retrograde precession of the disk, no numerical code to date has been shown to produce a disk tilt naturally. In this work, we report the first naturally tilted disk in non-magnetic cataclysmic variables using three-dimensional smoothed particle hydrodynamics. Our simulations show that after many hundreds of orbital periods, the disk has tilted on its own and this disk tilt is without the aid of radiation sources or magnetic fields. As the system orbits, the accretion stream strikes the bright spot (which is on the rim of the tilted disk) and flows over and under the disk on different flow paths. These different flow paths suggest the lift force as a source to disk tilt. Our results confirm the disk shape, disk structure, and negative superhump period and support the source to disk tilt, source to retrograde precession, and location associated with X-ray and He II emission from the disk as suggested in previous works. Our results identify the fundamental negative superhump frequency as the indicator of disk tilt around the line of nodes.

ON THE DYNAMICS AND ORIGIN OF HAUMEA'S MOONS

International Nuclear Information System (INIS)

Ćuk, Matija; Ragozzine, Darin; Nesvorný, David

2013-01-01

The dwarf planet Haumea has two large satellites, Namaka and Hi'iaka, which orbit at relatively large separations. Both moons have significant eccentricities and inclinations in a pattern that is consistent with a past orbital resonance. Based on our analysis, we find that the present system is not consistent with satellite formation close to the primary and tidal evolution through mean-motion resonances. We propose that Namaka experienced only limited tidal evolution, leading to the mutual 8:3 mean-motion resonance which redistributed eccentricities and inclinations between the moons. This scenario requires that the original orbit of Hi'iaka was mildly eccentric; we propose that this eccentricity was either primordial or acquired through encounters with other trans-Neptunian objects. Both dynamical stability and our preferred tidal evolution model imply that the moons' masses are only about one-half of previously estimated values, suggesting high albedos and low densities. Because the present orbits of the moons strongly suggest formation from a flat disk close to their present locations, we conclude that Hi'iaka and Namaka may be second-generation moons, formed after the breakup of a larger past moon, previously proposed as the parent body of the Haumea family. We derive plausible parameters of that moon, consistent with the current models of Haumea's formation. An interesting implication of this hypothesis is that Hi'iaka and Namaka may orbit retrograde with respect to Haumea's spin. Retrograde orbits of Haumea's moons would be in full agreement with available observations and our dynamical analysis, and could provide a unique confirmation of the ''disrupted satellite'' scenario for the origin of the family

Formation of Close-in Super-Earths by Giant Impacts: Effects of Initial Eccentricities and Inclinations of Protoplanets

Energy Technology Data Exchange (ETDEWEB)

Matsumoto, Yuji [Planetary Exploration Research Center, Chiba Institute of Technology, Narashino, Chiba, 275-0016 (Japan); Kokubo, Eiichiro, E-mail: ymatsumoto@cfca.nao.ac.jp [Center for Computational Astrophysics, National Astronomical Observatory of Japan, Osawa, Mitaka, Tokyo, 181-8588 (Japan)

2017-07-01

Recent observations have revealed the eccentricity and inclination distributions of close-in super-Earths. These distributions have the potential to constrain their formation processes. In the in situ formation scenario, the eccentricities and inclinations of planets are determined by gravitational scattering and collisions between protoplanets on the giant impact stage. We investigate the effect of the initial eccentricities and inclinations of protoplanets on the formation of close-in super-Earths. We perform N -body simulations of protoplanets in gas-free disks, changing the initial eccentricities and inclinations systematically. We find that while the eccentricities of protoplanets are well relaxed through their evolution, the inclinations are not. When the initial inclinations are small, they are not generally pumped up since scattering is less effective and collisions occur immediately after orbital crossing. On the other hand, when the initial inclinations are large, they tend to be kept large since collisional damping is less effective. Not only the resultant inclinations of planets, but also their number, eccentricities, angular momentum deficit, and orbital separations are affected by the initial inclinations of protoplanets.

Dynamics of the retrograde 1/1 mean motion resonance

Science.gov (United States)

Huang, Yukun; Li, Miao; Li, Junfeng; Gong, Shengping

2018-04-01

Mean motion resonances are very common in the solar system. Asteroids in mean motion resonances with giant planets have been studied for centuries. But it was not until recently that asteroids in retrograde mean motion resonances with Jupiter and Saturn were discovered. The newly discovered asteroid, 2015 BZ509 is confirmed to be the first asteroid in retrograde 1:1 mean motion resonance (or retrograde co-orbital resonance) with Jupiter, which gives rise to our interests in its unique resonant dynamics. In this study, we thoroughly investigate the phase-space structure of the retrograde 1:1 resonance within the framework of the circular restricted three-body problem. We begin by constructing a simple integrable approximation for the planar retrograde resonance with the Hamiltonian approach and show that the variables definition of the retrograde resonance is very different to the prograde one. When it comes to the disturbing function, we abandon the classical series expansion approach, whereas numerically carry out the averaging process on the disturbing function in closed form. The phase portrait of the retrograde 1:1 resonance is depicted with the level curves of the averaged Hamiltonian. We find that the topological structure of phase space for the retrograde 1:1 resonance is very different to other resonances, due to the consistent existence of the collision separatrix. And the surprising bifurcation of equilibrium point around 180° (i.e., the apocentric libration center) has never been found in any other mean motion resonances before. We thoroughly analyze the novel apocentric librations and find that close encounter with the planet does not always lead to the disruption of a stable apocentric libration. Afterwards, we examine the Kozai dynamics inside the mean motion resonance with the similar Hamiltonian approach and explain why the exact resonant point does not exist in the 3D retrograde 1:1 resonance model.

Orbital and Collisional Evolution of the Irregular Satellites

Science.gov (United States)

Nesvorný, David; Alvarellos, Jose L. A.; Dones, Luke; Levison, Harold F.

2003-07-01

The irregular moons of the Jovian planets are a puzzling part of the solar system inventory. Unlike regular satellites, the irregular moons revolve around planets at large distances in tilted and eccentric orbits. Their origin, which is intimately linked with the origin of the planets themselves, is yet to be explained. Here we report a study of the orbital and collisional evolution of the irregular satellites from times after their formation to the present epoch. The purpose of this study is to find out the features of the observed irregular moons that can be attributed to this evolution and separate them from signatures of the formation process. We numerically integrated ~60,000 test satellite orbits to map orbital locations that are stable on long time intervals. We found that the orbits highly inclined to the ecliptic are unstable due to the effect of the Kozai resonance, which radially stretches them so that satellites either escape from the Hill sphere, collide with massive inner moons, or impact the parent planet. We also found that prograde satellite orbits with large semimajor axes are unstable due to the effect of the evection resonance, which locks the orbit's apocenter to the apparent motion of the Sun around the parent planet. In such a resonance, the effect of solar tides on a resonant moon accumulates at each apocenter passage of the moon, which causes a radially outward drift of its orbital apocenter; once close to the Hill sphere, the moon escapes. By contrast, retrograde moons with large orbital semimajor axes are long-lived. We have developed an analytic model of the distant satellite orbits and used it to explain the results of our numerical experiments. In particular, we analytically studied the effect of the Kozai resonance. We numerically integrated the orbits of the 50 irregular moons (known by 2002 August 16) for 108 yr. All orbits were stable on this time interval and did not show any macroscopic variations that would indicate

Mapping stable direct and retrograde orbits around the triple system of asteroids (45) Eugenia

Science.gov (United States)

Araujo, R. A. N.; Moraes, R. V.; Prado, A. F. B. A.; Winter, O. C.

2017-12-01

It is widely accepted that knowing the composition and the orbital evolution of asteroids might help us to understand the process of formation of the Solar system. It is also known that asteroids can represent a threat to our planet. Such an important role has made space missions to asteroids a very popular topic in current astrodynamics and astronomy studies. Taking into account the increasing interest in space missions to asteroids, especially to multiple systems, we present a study that aims to characterize the stable and unstable regions around the triple system of asteroids (45) Eugenia. The goal is to characterize the unstable and stable regions of this system and to make a comparison with the system 2001 SN263, which is the target of the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) mission. A new concept was used for mapping orbits, by considering the disturbance received by the spacecraft from all perturbing forces individually. This method has also been applied to (45) Eugenia. We present the stable and unstable regions for particles with relative inclination between 0° and 180°. We found that (45) Eugenia presents larger stable regions for both prograde and retrograde cases. This is mainly because the satellites of this system are small when compared to the primary body, and because they are not close to each other. We also present a comparison between these two triple systems, and we discuss how these results can guide us in the planning of future missions.

ON THE DYNAMICS AND ORIGIN OF HAUMEA'S MOONS

Energy Technology Data Exchange (ETDEWEB)

Ćuk, Matija [Carl Sagan Center, SETI Institute, 189 North Bernardo Avenue, Mountain View, CA 94043 (United States); Ragozzine, Darin [Department of Astronomy, University of Florida, Gainesville, FL 32611 (United States); Nesvorný, David, E-mail: mcuk@seti.org [Southwest Research Institute, Boulder, CO 80302 (United States)

2013-10-01

The dwarf planet Haumea has two large satellites, Namaka and Hi'iaka, which orbit at relatively large separations. Both moons have significant eccentricities and inclinations in a pattern that is consistent with a past orbital resonance. Based on our analysis, we find that the present system is not consistent with satellite formation close to the primary and tidal evolution through mean-motion resonances. We propose that Namaka experienced only limited tidal evolution, leading to the mutual 8:3 mean-motion resonance which redistributed eccentricities and inclinations between the moons. This scenario requires that the original orbit of Hi'iaka was mildly eccentric; we propose that this eccentricity was either primordial or acquired through encounters with other trans-Neptunian objects. Both dynamical stability and our preferred tidal evolution model imply that the moons' masses are only about one-half of previously estimated values, suggesting high albedos and low densities. Because the present orbits of the moons strongly suggest formation from a flat disk close to their present locations, we conclude that Hi'iaka and Namaka may be second-generation moons, formed after the breakup of a larger past moon, previously proposed as the parent body of the Haumea family. We derive plausible parameters of that moon, consistent with the current models of Haumea's formation. An interesting implication of this hypothesis is that Hi'iaka and Namaka may orbit retrograde with respect to Haumea's spin. Retrograde orbits of Haumea's moons would be in full agreement with available observations and our dynamical analysis, and could provide a unique confirmation of the ''disrupted satellite'' scenario for the origin of the family.

Effects of solar radiation on the orbits of small particles

Science.gov (United States)

Lyttleton, R. A.

1976-01-01

A modification of the Robertson (1937) equations of particle motion in the presence of solar radiation is developed which allows for partial reflection of sunlight as a result of rapid and varying particle rotations caused by interaction with the solar wind. The coefficients and forces in earlier forms of the equations are compared with those in the present equations, and secular rates of change of particle orbital elements are determined. Orbital dimensions are calculated in terms of time, probable sizes and densities of meteoric and cometary particles are estimated, and times of infall to the sun are computed for a particle moving in an almost circular orbit and a particle moving in an elliptical orbit of high eccentricity. Changes in orbital elements are also determined for particles from a long-period sun-grazing comet. The results show that the time of infall to the sun from a highly eccentric orbit is substantially shorter than from a circular orbit with a radius equal to the mean distance in the eccentric orbit. The possibility is considered that the free orbital kinetic energy of particles drawn into the sun may be the energy source for the solar corona.

Transiting exoplanets from the CoRoT space mission . XIX. CoRoT-23b: a dense hot Jupiter on an eccentric orbit

DEFF Research Database (Denmark)

Rouan, D.; Parviainen, H.; Moutou, C.

2012-01-01

We report the detection of CoRoT-23b, a hot Jupiter transiting in front of its host star with a period of 3.6314 ± 0.0001 days. This planet was discovered thanks to photometric data secured with the CoRoT satellite, combined with spectroscopic radial velocity (RV) measurements. A photometric search...... to be 7 Gyr, not far from the transition to subgiant, in agreement with the rather large stellar radius. The two features of a significant eccentricity of the orbit and of a fairly high density are fairly uncommon for a hot Jupiter. The high density is, however, consistent with a model of contraction...... is more than a few 105, a value that is the lower bound of the usually expected range. Even if CoRoT-23b  features a density and an eccentricity that are atypical of a hot Jupiter, it is thus not an enigmatic object....

Formation of Tidally Induced Bars in Galactic Flybys: Prograde versus Retrograde Encounters

Science.gov (United States)

Łokas, Ewa L.

2018-04-01

Bars in disk galaxies can be formed by interactions with other systems, including those of comparable mass. It has long been established that the effect of such interactions on galaxy morphology depends strongly on the orbital configuration, in particular the orientation of the intrinsic spin of the galactic disk with respect to its orbital angular momentum. Prograde encounters modify the morphology strongly, including the formation of tidally induced bars, while retrograde flybys should have little effect on morphology. Recent works on the subject reached conflicting conclusions, one using the impulse approximation and claiming no dependence on this angle in the properties of tidal bars. To resolve the controversy, we performed self-consistent N-body simulations of hyperbolic encounters between two identical Milky Way-like galaxies assuming different velocities and impact parameters, with one of the galaxies on a prograde and the other on a retrograde orbit. The galaxies were initially composed of an exponential stellar disk and an NFW dark halo, and they were stable against bar formation in isolation for 3 Gyr. We find that strong tidally induced bars form only in galaxies on prograde orbits. For smaller impact parameters and lower relative velocities, the bars are stronger and have lower pattern speeds. Stronger bars undergo extended periods of buckling instability that thicken their vertical structure. The encounters also lead to the formation of two-armed spirals with strength inversely proportional to the strength of the bars. We conclude that proper modeling of prograde and retrograde encounters cannot rely on the simplest impulse approximation.

Constraining stellar binary black hole formation scenarios with eLISA eccentricity measurements

OpenAIRE

Nishizawa, Atsushi; Sesana, Alberto; Berti, Emanuele; Klein, Antoine

2016-01-01

A space-based interferometer such as eLISA could observe few to few thousands progenitors of black hole binaries (BHBs) similar to those recently detected by Advanced LIGO. Gravitational radiation circularizes the orbit during inspiral, but some BHBs retain a measurable eccentricity at the low frequencies where eLISA is most sensitive. The eccentricity of a BHB carries precious information about its formation channel: BHBs formed in the field, in globular clusters, or close to a massive black...

Limits on stellar companions to exoplanet host stars with eccentric planets

International Nuclear Information System (INIS)

Kane, Stephen R.; Hinkel, Natalie R.; Howell, Steve B.; Horch, Elliott P.; Feng, Ying; Wright, Jason T.; Ciardi, David R.; Everett, Mark E.; Howard, Andrew W.

2014-01-01

Though there are now many hundreds of confirmed exoplanets known, the binarity of exoplanet host stars is not well understood. This is particularly true of host stars that harbor a giant planet in a highly eccentric orbit since these are more likely to have had a dramatic dynamical history that transferred angular momentum to the planet. Here we present observations of four exoplanet host stars that utilize the excellent resolving power of the Differential Speckle Survey Instrument on the Gemini North telescope. Two of the stars are giants and two are dwarfs. Each star is host to a giant planet with an orbital eccentricity >0.5 and whose radial velocity (RV) data contain a trend in the residuals to the Keplerian orbit fit. These observations rule out stellar companions 4-8 mag fainter than the host star at passbands of 692 nm and 880 nm. The resolution and field of view of the instrument result in exclusion radii of 0.''05-1.''4, which excludes stellar companions within several AU of the host star in most cases. We further provide new RVs for the HD 4203 system that confirm that the linear trend previously observed in the residuals is due to an additional planet. These results place dynamical constraints on the source of the planet's eccentricities, place constraints on additional planetary companions, and inform the known distribution of multiplicity amongst exoplanet host stars.

SECRETLY ECCENTRIC: THE GIANT PLANET AND ACTIVITY CYCLE OF GJ 328

International Nuclear Information System (INIS)

Robertson, Paul; Endl, Michael; Cochran, William D.; MacQueen, Phillip J.; Boss, Alan P.

2013-01-01

We announce the discovery of a ∼2 Jupiter-mass planet in an eccentric 11 yr orbit around the K7/M0 dwarf GJ 328. Our result is based on 10 years of radial velocity (RV) data from the Hobby-Eberly and Harlan J. Smith telescopes at McDonald Observatory, and from the Keck Telescope at Mauna Kea. Our analysis of GJ 328's magnetic activity via the Na I D features reveals a long-period stellar activity cycle, which creates an additional signal in the star's RV curve with amplitude 6-10 m s –1 . After correcting for this stellar RV contribution, we see that the orbit of the planet is more eccentric than suggested by the raw RV data. GJ 328b is currently the most massive, longest-period planet discovered around a low-mass dwarf

Loners, Groupies, and Long-term Eccentricity (and Inclination) Behavior: Insights from Secular Theory

Science.gov (United States)

Van Laerhoven, Christa L.

2015-05-01

Considering the secular dynamics of multi-planet systems provides substantial insight into the interactions between planets in those systems. Secular interactions are those that don't involve knowing where a planet is along its orbit, and they dominate when planets are not involved in mean motion resonances. These interactions exchange angular momentum among the planets, evolving their eccentricities and inclinations. To second order in the planets' eccentricities and inclinations, the eccentricity and inclination perturbations are decoupled. Given the right variable choice, the relevant differential equations are linear and thus the eccentricity and inclination behaviors can be described as a sum of eigenmodes. Since the underlying structure of the secular eigenmodes can be calculated using only the planets' masses and semi-major axes, one can elucidate the eccentricity and inclination behavior of planets in exoplanet systems even without knowing the planets' current eccentricities and inclinations. I have calculated both the eccentricity and inclination secular eigenmodes for the population of known multi-planet systems whose planets have well determined masses and periods. Using this catalog of secular character, I will discuss the prevalence of dynamically grouped planets ('groupies') versus dynamically uncoupled planets ('loners') and how this relates to the exoplanets' long-term eccentricity and inclination behavior. I will also touch on the distribution of the secular eigenfreqiencies.

How to Make Eccentricity Cycles in Stratigraphy: the Role of Compaction

Science.gov (United States)

Liu, W.; Hinnov, L.; Wu, H.; Pas, D.

2017-12-01

Milankovitch cycles from astronomically driven climate variations have been demonstrated as preserved in cyclostratigraphy throughout geologic time. These stratigraphic cycles have been identified in many types of proxies, e.g., gamma ray, magnetic susceptibility, oxygen isotopes, carbonate content, grayscale, etc. However, the commonly prominent spectral power of orbital eccentricity cycles in stratigraphy is paradoxical to insolation, which is dominated by precession index power. How is the spectral power transferred from precession to eccentricity in stratigraphy? Nonlinear sedimentation and bioturbation have long been identified as players in this transference. Here, we propose that in the absence of bioturbation differential compaction can generate the transference. Using insolation time series, we trace the steps by which insolation is transformed into stratigraphy, and how differential compaction of lithology acts to transfer spectral power from precession to eccentricity. Differential compaction is applied to unique values of insolation, which is assumed to control the type of deposited sediment. High compaction is applied to muds, and progressively lower compaction is applied to silts and sands, or carbonate. Linear differential compaction promotes eccentricity spectral power, but nonlinear differential compaction elevates eccentricity spectral power to dominance and precession spectral power to near collapse as is often observed in real stratigraphy. Keywords: differential compaction, cyclostratigraphy, insolation, eccentricity

ON THE ORBIT OF EXOPLANET WASP-12b

International Nuclear Information System (INIS)

Campo, Christopher J.; Harrington, Joseph; Hardy, Ryan A.; Stevenson, Kevin B.; Nymeyer, Sarah; Lust, Nate B.; Blecic, Jasmina; Britt, Christopher B. T.; Bowman, William C.; Ragozzine, Darin; Anderson, David R.; Hellier, Coel; Maxted, Pierre F. L.; Collier-Cameron, Andrew; Wheatley, Peter J.; Loredo, Thomas J.; Deming, Drake; Hebb, Leslie; Pollaco, Don; West, Richard G.

2011-01-01

We observed two secondary eclipses of the exoplanet WASP-12b using the Infrared Array Camera on the Spitzer Space Telescope. The close proximity of WASP-12b to its G-type star results in extreme tidal forces capable of inducing apsidal precession with a period as short as a few decades. This precession would be measurable if the orbit had a significant eccentricity, leading to an estimate of the tidal Love number and an assessment of the degree of central concentration in the planetary interior. An initial ground-based secondary-eclipse phase reported by Lopez-Morales et al. (0.510 ± 0.002) implied eccentricity at the 4.5σ level. The spectroscopic orbit of Hebb et al. has eccentricity 0.049 ± 0.015, a 3σ result, implying an eclipse phase of 0.509 ± 0.007. However, there is a well-documented tendency of spectroscopic data to overestimate small eccentricities. Our eclipse phases are 0.5010 ± 0.0006 (3.6 and 5.8 μm) and 0.5006 ± 0.0007 (4.5 and 8.0 μm). An unlikely orbital precession scenario invoking an alignment of the orbit during the Spitzer observations could have explained this apparent discrepancy, but the final eclipse phase of Lopez-Morales et al. (0.510 ± +0.007 -0.006 ) is consistent with a circular orbit at better than 2σ. An orbit fit to all the available transit, eclipse, and radial-velocity data indicates precession at <1σ; a non-precessing solution fits better. We also comment on analysis and reporting for Spitzer exoplanet data in light of recent re-analyses.

THEORY OF SECULAR CHAOS AND MERCURY'S ORBIT

International Nuclear Information System (INIS)

Lithwick, Yoram; Wu Yanqin

2011-01-01

We study the chaotic orbital evolution of planetary systems, focusing on secular (i.e., orbit-averaged) interactions, which dominate on long timescales. We first focus on the evolution of a test particle that is forced by multiple planets. To linear order in eccentricity and inclination, its orbit precesses with constant frequencies. But nonlinearities modify the frequencies, and can shift them into and out of resonance with either the planets' eigenfrequencies (forming eccentricity or inclination secular resonances), or with linear combinations of those frequencies (forming mixed high-order secular resonances). The overlap of these nonlinear secular resonances drives secular chaos. We calculate the locations and widths of nonlinear secular resonances, display them together on a newly developed map (the 'map of the mean momenta'), and find good agreement between analytical and numerical results. This map also graphically demonstrates how chaos emerges from overlapping secular resonances. We then apply this newfound understanding to Mercury to elucidate the origin of its orbital chaos. We find that since Mercury's two free precession frequencies (in eccentricity and inclination) lie within ∼25% of two other eigenfrequencies in the solar system (those of the Jupiter-dominated eccentricity mode and the Venus-dominated inclination mode), secular resonances involving these four modes overlap and cause Mercury's chaos. We confirm this with N-body integrations by showing that a slew of these resonant angles alternately librate and circulate. Our new analytical understanding allows us to calculate the criterion for Mercury to become chaotic: Jupiter and Venus must have eccentricity and inclination of a few percent. The timescale for Mercury's chaotic diffusion depends sensitively on the forcing. As it is, Mercury appears to be perched on the threshold for chaos, with an instability timescale comparable to the lifetime of the solar system.

Posttraumatic Orbital Emphysema: A Numerical Model

Directory of Open Access Journals (Sweden)

Andrzej Skorek

2014-01-01

Full Text Available Orbital emphysema is a common symptom accompanying orbital fracture. The pathomechanism is still not recognized and the usually assumed cause, elevated pressure in the upper airways connected with sneezing or coughing, does not always contribute to the occurrence of this type of fracture. Observations based on the finite model (simulating blowout type fracture of the deformations of the inferior orbital wall after a strike in its lower rim. Authors created a computer numeric model of the orbit with specified features—thickness and resilience modulus. During simulation an evenly spread 14400 N force was applied to the nodular points in the inferior rim (the maximal value not causing cracking of the outer rim, but only ruptures in the inferior wall. The observation was made from 1·10-3 to 1·10-2 second after a strike. Right after a strike dislocations of the inferior orbital wall toward the maxillary sinus were observed. Afterwards a retrograde wave of the dislocation of the inferior wall toward the orbit was noticed. Overall dislocation amplitude reached about 6 mm. Based on a numeric model of the orbit submitted to a strike in the inferior wall an existence of a retrograde shock wave causing orbital emphysema has been found.

TOWARD A DETERMINISTIC MODEL OF PLANETARY FORMATION. VII. ECCENTRICITY DISTRIBUTION OF GAS GIANTS

International Nuclear Information System (INIS)

Ida, S.; Lin, D. N. C.; Nagasawa, M.

2013-01-01

The ubiquity of planets and diversity of planetary systems reveal that planet formation encompasses many complex and competing processes. In this series of papers, we develop and upgrade a population synthesis model as a tool to identify the dominant physical effects and to calibrate the range of physical conditions. Recent planet searches have led to the discovery of many multiple-planet systems. Any theoretical models of their origins must take into account dynamical interactions between emerging protoplanets. Here, we introduce a prescription to approximate the close encounters between multiple planets. We apply this method to simulate the growth, migration, and dynamical interaction of planetary systems. Our models show that in relatively massive disks, several gas giants and rocky/icy planets emerge, migrate, and undergo dynamical instability. Secular perturbation between planets leads to orbital crossings, eccentricity excitation, and planetary ejection. In disks with modest masses, two or less gas giants form with multiple super-Earths. Orbital stability in these systems is generally maintained and they retain the kinematic structure after gas in their natal disks is depleted. These results reproduce the observed planetary mass-eccentricity and semimajor axis-eccentricity correlations. They also suggest that emerging gas giants can scatter residual cores to the outer disk regions. Subsequent in situ gas accretion onto these cores can lead to the formation of distant (∼> 30 AU) gas giants with nearly circular orbits

K2-232 b: a transiting warm Saturn on an eccentric P = 11.2 d orbit around a V = 9.9 star

Science.gov (United States)

Brahm, R.; Espinoza, N.; Jordán, A.; Rojas, F.; Sarkis, P.; Díaz, M. R.; Rabus, M.; Drass, H.; Lachaume, R.; Soto, M. G.; Jenkins, J. S.; Jones, M. I.; Henning, Th; Pantoja, B.; Vučković, M.

2018-06-01

We report the discovery of K2-232 b using photometric data of the Kepler K2 satellite coupled with ground-based spectroscopic observations. K2-232 b has a mass of MP = 0.397 ± 0.037 MJ, a radius of RP = 1.00 ± 0.020 RJ, and a moderately low equilibrium temperature of Teq = 1030 ± 15 K due to its relatively large star-planet separation of a = 0.1036 au. K2-232 b orbits its bright (V = 9.9) late F-type host star in an eccentric orbit (e = 0.258 ± 0.025) every 11.2 d, and is one of only four well-characterized warm Jupiters having host stars brighter than V = 10. We estimate a heavy element content of 20 ± 7 M⊕ for K2-232 b, which is consistent with standard models of giant planet formation. The bright host star of K2-232 b makes this system a well-suited target for detailed follow-up observations that will aid in the study of the atmospheres and orbital evolution of giant planets at moderate separations from their host stars.

A discussion of the eccentric binary hypothesis for transient X-ray sources

International Nuclear Information System (INIS)

Avni, Y.; Goldman, I.

1979-01-01

The eccentric binary hypothesis for transient x-ray sources in the framework of the gradual acceleration stellar wind model proposed by Barlow and Cohen is examined. It is found that a consideration of the ratio of maximum to minimum luminosities and of the ratio of the durations of the high and low states, for a typical transient x-ray source, yields a rather high eccentricity, despite the gradual acceleration of the wind. When typical physical parameters for the binary members are taken into account, we find that a consistent description is possible only for very eccentric orbits (e>=0.9), thus the model is inadequate as a general explanation of the x-ray transient phenomenon. The recurrent transient x-ray source 4U 1630-47, which was considered in ihe past to be a realization of the eccentric binary model is studied and it is demonstrated that it cannot be described consistently within the framework of the model, unless the optical primary is very peculiar. (author)

Pseudotumor of the distal common bile duct at endoscopic retrograde cholangiopancreatography

Science.gov (United States)

Tan, Justin H.; Coakley, Fergus V; Wang, Zhen J.; Poder, Liina; Webb, Emily; Yeh, Benjamin M.

2010-01-01

Background Prior studies have described a pseudocalculus appearance in the distal common bile duct as a normal variant at cholangiography. The objective of this study is to describe the occurrence of pseudotumor in the distal common bile duct at endoscopic retrograde cholangiopancreatography (ERCP). Methods Nine patients who underwent ERCP between May 2004 and July 2008 were identified as having a transient eccentric mural-based filling defect in the distal common bile duct. A single reader systematically reviewed all studies and recorded the imaging findings. Results The mean diameter of the filling defect was 9 mm (range, 5 to 11). Eight patients had resolution of the filling defect during the same ERCP or on a subsequent ERCP, and in 2 of these patients the inferior border of the filling defect was not well visualized. The other patient underwent surgical resection of a presumed tumor with no evidence of malignancy on surgical pathology. Conclusion An eccentric mural-based filling defect in the distal common bile duct can be artifactual in nature and may reflect transient contraction of the sphincter of Oddi. Recognition of this pseudotumor may help avoid unnecessary surgery. PMID:21724120

Retrograde peri-implantitis

Directory of Open Access Journals (Sweden)

Mohamed Jumshad

2010-01-01

Full Text Available Retrograde peri-implantitis constitutes an important cause for implant failure. Retrograde peri-implantitis may sometimes prove difficult to identify and hence institution of early treatment may not be possible. This paper presents a report of four cases of (the implant placed developing to retrograde peri-implantitis. Three of these implants were successfully restored to their fully functional state while one was lost due to extensive damage. The paper highlights the importance of recognizing the etiopathogenic mechanisms, preoperative assessment, and a strong postoperative maintenance protocol to avoid retrograde peri-implant inflammation.

Short gamma-ray bursts and gravitational-wave observations from eccentric compact binaries

Science.gov (United States)

Tan, Wei-Wei; Fan, Xi-Long; Wang, F. Y.

2018-03-01

Mergers of compact binaries, such as binary neutron stars (BNSs), neutron star-black hole binaries (NSBHs) and binary black holes (BBHs), are expected to be the best candidates for sources of gravitational waves (GWs) and the leading theoretical models for short gamma-ray bursts (SGRBs). Based on observations of SGRBs, we can derive the merger rates of these compact binaries and study stochastic GW backgrounds (SGWBs) or the co-detection rates of GWs associated with SGRBs (GW-SGRBs). Before that, however, the most important thing is to derive the GW spectrum from a single GW source. Usually, a GW spectrum from a circular-orbit binary is assumed. However, observations of the large spatial offsets of SGRBs from their host galaxies imply that SGRB progenitors may be formed by dynamical processes and will merge with residual eccentricities (er). The orbital eccentricity has an important effect on GW spectra and therefore on the SGWB and GW-SGRB co-detection rate. Our results show that the power spectra of SGWBs from eccentric compact binaries are greatly suppressed at low frequencies (e.g. f ≲ 1 Hz). In particular, SGWBs from binaries with high residual eccentricities (e.g. er ≳ 0.1 for BNSs) will be hard to detect (above the detection frequency of ˜ 100 Hz). Regarding the co-detection rates of GW-SGRB events, they could be ˜1.4 times higher than the circular case within some particular ranges of er (e.g. 0.01 ≲ er ≲ 0.1 for BBHs), but greatly reduced for high residual eccentricities (e.g. er > 0.1 for BNSs). In general, BBH progenitors produce 200 and 10 times higher GW-SGRB events than BNS and NSBH progenitors, respectively. Therefore, binaries with low residual eccentricities (e.g. 0.001 ≲ er ≲ 0.1) and high total masses will be easier to detect by Advanced LIGO (aLIGO). However, only a small fraction of BBHs can be SGRB progenitors (if they can produce SGRBs), because the predicted GW-SGRB event rate (60˜100 per year) is too high compared with recent

DAY-SIDE z'-BAND EMISSION AND ECCENTRICITY OF WASP-12b

International Nuclear Information System (INIS)

Lopez-Morales, Mercedes; Rogers, Justin C.; Coughlin, Jeffrey L.; Sing, David K.; Burrows, Adam; Spiegel, David S.; Apai, Daniel; Adams, Elisabeth R.

2010-01-01

We report the detection of the eclipse of the very hot Jupiter WASP-12b via z'-band time-series photometry obtained with the 3.5 m Astrophysical Research Consortium telescope at Apache Point Observatory. We measure a decrease in flux of 0.082% ± 0.015% during the passage of the planet behind the star. That planetary flux is equally well reproduced by atmospheric models with and without extra absorbers, and blackbody models with f ≥ 0.585 ± 0.080. It is therefore necessary to measure the planet at other wavelengths to further constrain its atmospheric properties. The eclipse appears centered at phase φ = 0.5100 +0.0072 -0.0061 , consistent with an orbital eccentricity of |ecos ω| = 0.016 +0.011 -0.009 (see note at the end of Section 4). If the orbit of the planet is indeed eccentric, the large radius of WASP-12b can be explained by tidal heating.

Non-linear hydrodynamic instability and turbulence in eccentric astrophysical discs with vertical structure

Science.gov (United States)

Wienkers, A. F.; Ogilvie, G. I.

2018-04-01

Non-linear evolution of the parametric instability of inertial waves inherent to eccentric discs is studied by way of a new local numerical model. Mode coupling of tidal deformation with the disc eccentricity is known to produce exponentially growing eccentricities at certain mean-motion resonances. However, the details of an efficient saturation mechanism balancing this growth still are not fully understood. This paper develops a local numerical model for an eccentric quasi-axisymmetric shearing box which generalises the often-used cartesian shearing box model. The numerical method is an overall second order well-balanced finite volume method which maintains the stratified and oscillatory steady-state solution by construction. This implementation is employed to study the non-linear outcome of the parametric instability in eccentric discs with vertical structure. Stratification is found to constrain the perturbation energy near the mid-plane and localise the effective region of inertial wave breaking that sources turbulence. A saturated marginally sonic turbulent state results from the non-linear breaking of inertial waves and is subsequently unstable to large-scale axisymmetric zonal flow structures. This resulting limit-cycle behaviour reduces access to the eccentric energy source and prevents substantial transport of angular momentum radially through the disc. Still, the saturation of this parametric instability of inertial waves is shown to damp eccentricity on a time-scale of a thousand orbital periods. It may thus be a promising mechanism for intermittently regaining balance with the exponential growth of eccentricity from the eccentric Lindblad resonances and may also help explain the occurrence of "bursty" dynamics such as the superhump phenomenon.

Impact of eccentricity build-up and graveyard disposal Strategies on MEO navigation constellations

Science.gov (United States)

Radtke, Jonas; Domínguez-González, Raúl; Flegel, Sven K.; Sánchez-Ortiz, Noelia; Merz, Klaus

2015-12-01

With currently two constellations being in or close to the build-up phase, in a few years the Medium Earth Orbit (MEO) region will be populated with four complete navigation systems in relatively close orbital altitudes: The American GPS, Russian GLONASS, European Galileo, and Chinese BeiDou. To guarantee an appropriate visibility of constellation satellites from Earth, these constellations rely on certain defined orbits. For this, both the repeat pattern, which is basically defined by the semimajor axis and inclination, as well as the orbital planes, which are defined by the right ascension of ascending node, are determining values. To avoid an overcrowding of the region of interest, the disposal of satellites after their end-of-life is recommended. However, for the MEO region, no internationally agreed mitigation guidelines exist. Because of their distances to Earth, ordinary disposal manoeuvres leading to a direct or delayed re-entry due to atmospheric drag are not feasible: The needed fuel masses for such manoeuvres are by far above the reasonable limits and available fuel budgets. Thus, additional approaches have to be applied. For this, in general two options exist: disposal to graveyard orbits or the disposal to eccentricity build-up orbits. In the study performed, the key criterion for the graveyard strategy is that the disposed spacecraft must keep a safe minimum distance to the altitude of the active constellation on a long-term time scale of up to 200 years. This constraint imposes stringent requirements on the stability of the graveyard orbit. Similar disposals are also performed for high LEO satellites and disposed GEO payloads. The eccentricity build-up strategy on the other hand uses resonant effects between the Earth's geopotential, the Sun and the Moon. Depending on the initial conditions, these can cause a large eccentricity build-up, which finally can lead to a re-entry of the satellite. In this paper, the effects of applying either the first or

Fast prediction and evaluation of eccentric inspirals using reduced-order models

Science.gov (United States)

Barta, Dániel; Vasúth, Mátyás

2018-06-01

A large number of theoretically predicted waveforms are required by matched-filtering searches for the gravitational-wave signals produced by compact binary coalescence. In order to substantially alleviate the computational burden in gravitational-wave searches and parameter estimation without degrading the signal detectability, we propose a novel reduced-order-model (ROM) approach with applications to adiabatic 3PN-accurate inspiral waveforms of nonspinning sources that evolve on either highly or slightly eccentric orbits. We provide a singular-value decomposition-based reduced-basis method in the frequency domain to generate reduced-order approximations of any gravitational waves with acceptable accuracy and precision within the parameter range of the model. We construct efficient reduced bases comprised of a relatively small number of the most relevant waveforms over three-dimensional parameter-space covered by the template bank (total mass 2.15 M⊙≤M ≤215 M⊙ , mass ratio 0.01 ≤q ≤1 , and initial orbital eccentricity 0 ≤e0≤0.95 ). The ROM is designed to predict signals in the frequency band from 10 Hz to 2 kHz for aLIGO and aVirgo design sensitivity. Beside moderating the data reduction, finer sampling of fiducial templates improves the accuracy of surrogates. Considerable increase in the speedup from several hundreds to thousands can be achieved by evaluating surrogates for low-mass systems especially when combined with high-eccentricity.

Applicability of meteor radiant determination methods depending on orbit type. I. High-eccentric orbits

Science.gov (United States)

Svoren, J.; Neslusan, L.; Porubcan, V.

1993-07-01

It is evident that there is no uniform method of calculating meteor radiants which would yield reliable results for all types of cometary orbits. In the present paper an analysis of this problem is presented, together with recommended methods for various types of orbits. Some additional methods resulting from mathematical modelling are presented and discussed together with Porter's, Steel-Baggaley's and Hasegawa's methods. In order to be able to compare how suitable the application of the individual radiant determination methods is, it is necessary to determine the accuracy with which they approximate real meteor orbits. To verify the accuracy with which the orbit of a meteoroid with at least one node at 1 AU fits the original orbit of the parent body, we applied the Southworth-Hawkins D-criterion (Southworth, R.B., Hawkins, G.S.: 1963, Smithson. Contr. Astrophys 7, 261). D0.2 the fit is rather poor and the change of orbit unrealistic. The optimal methods with the smallest values of D for given types of orbits are shown in two series of six plots. The new method of rotation around the line of apsides we propose is very appropriate in the region of small inclinations. There is no doubt that Hasegawa's omega-adjustment method (Hasegawa, I.: 1990, Publ. Astron. Soc. Japan 42, 175) has the widest application. A comparison of the theoretical radiants with the observed radiants of seven known meteor showers is also presented.

Jupiter Analogs Orbit Stars with an Average Metallicity Close to That of the Sun

DEFF Research Database (Denmark)

Buchhave, Lars A.; Bitsch, Bertram; Johansen, Anders

2018-01-01

Jupiter played an important role in determining the structure and configuration of the Solar System. Whereas hot-Jupiter type exoplanets preferentially form around metal-rich stars, the conditions required for the formation of planets with masses, orbits, and eccentricities comparable to Jupiter...... (Jupiter analogs) are unknown. Using spectroscopic metallicities, we show that stars hosting Jupiter analogs have an average metallicity close to solar, in contrast to their hot-Jupiter and eccentric cool-Jupiter counterparts, which orbit stars with super-solar metallicities. Furthermore......, the eccentricities of Jupiter analogs increase with host-star metallicity, suggesting that planet-planet scatterings producing highly eccentric cool Jupiters could be more common in metal-rich environments. To investigate a possible explanation for these metallicity trends, we compare the observations to numerical...

NanoSail - D Orbital and Attitude Dynamics

Science.gov (United States)

Heaton, Andrew F.; Faller, Brent F.; Katan, Chelsea K.

2013-01-01

NanoSail-D unfurled January 20th, 2011 and successfully demonstrated the deployment and deorbit capability of a solar sail in low Earth orbit. The orbit was strongly perturbed by solar radiation pressure, aerodynamic drag, and oblate gravity which were modeled using STK HPOP. A comparison of the ballistic coefficient history to the orbit parameters exhibits a strong relationship between orbital lighting, the decay rate of the mean semi-major axis and mean eccentricity. A similar comparison of mean solar area using the STK HPOP solar radiation pressure model exhibits a strong correlation of solar radiation pressure to mean eccentricity and mean argument of perigee. NanoSail-D was not actively controlled and had no capability on-board for attitude or orbit determination. To estimate attitude dynamics we created a 3-DOF attitude dynamics simulation that incorporated highly realistic estimates of perturbing forces into NanoSail-D torque models. By comparing the results of this simulation to the orbital behavior and ground observations of NanoSail-D, we conclude that there is a coupling between the orbit and attitude dynamics as well as establish approximate limits on the location of the NanoSail-D solar center of pressure. Both of these observations contribute valuable data for future solar sail designs and missions.

Detection of retrograde gas streaming in the SB0 galaxy NGC 4546

International Nuclear Information System (INIS)

Galletta, G.

1987-01-01

Spectroscopic observations are reported of the almost edge-on SB0 galaxy NGC 4546 which reveal a striking discordance between the derived emission and absorption-line velocities. The gas clouds show velocities that are similar in amplitude but opposite in direction from the stars. This discordance is seen in observations obtained through slits oriented in a wide range of position angles. NGC 4546 is thus, at present, unique as a disk system exhibiting large-scale retrograde motions relative to the stellar component. Orbits elongated both along the bar major axis (prograde, stars) and along the bar intermediate axis (retrograde, gas) are found. The possibility that this material originated from an infall is discussed. 27 references

Exo-Milankovitch Cycles. I. Orbits and Rotation States

Science.gov (United States)

Deitrick, Russell; Barnes, Rory; Quinn, Thomas R.; Armstrong, John; Charnay, Benjamin; Wilhelm, Caitlyn

2018-02-01

The obliquity of the Earth, which controls our seasons, varies by only ∼2.°5 over ∼40,000 years, and its eccentricity varies by only ∼0.05 over 100,000 years. Nonetheless, these small variations influence Earth’s ice ages. For exoplanets, however, variations can be significantly larger. Previous studies of the habitability of moonless Earth-like exoplanets have found that high obliquities, high eccentricities, and dynamical variations can extend the outer edge of the habitable zone by preventing runaway glaciation (snowball states). We expand upon these studies by exploring the orbital dynamics with a semianalytic model that allows us to map broad regions of parameter space. We find that, in general, the largest drivers of obliquity variations are secular spin–orbit resonances. We show how the obliquity varies in several test cases, including Kepler-62 f, across a wide range of orbital and spin parameters. These obliquity variations, alongside orbital variations, will have a dramatic impact on the climates of such planets.

Waveform model for an eccentric binary black hole based on the effective-one-body-numerical-relativity formalism

Science.gov (United States)

Cao, Zhoujian; Han, Wen-Biao

2017-08-01

Binary black hole systems are among the most important sources for gravitational wave detection. They are also good objects for theoretical research for general relativity. A gravitational waveform template is important to data analysis. An effective-one-body-numerical-relativity (EOBNR) model has played an essential role in the LIGO data analysis. For future space-based gravitational wave detection, many binary systems will admit a somewhat orbit eccentricity. At the same time, the eccentric binary is also an interesting topic for theoretical study in general relativity. In this paper, we construct the first eccentric binary waveform model based on an effective-one-body-numerical-relativity framework. Our basic assumption in the model construction is that the involved eccentricity is small. We have compared our eccentric EOBNR model to the circular one used in the LIGO data analysis. We have also tested our eccentric EOBNR model against another recently proposed eccentric binary waveform model; against numerical relativity simulation results; and against perturbation approximation results for extreme mass ratio binary systems. Compared to numerical relativity simulations with an eccentricity as large as about 0.2, the overlap factor for our eccentric EOBNR model is better than 0.98 for all tested cases, including spinless binary and spinning binary, equal mass binary, and unequal mass binary. Hopefully, our eccentric model can be the starting point to develop a faithful template for future space-based gravitational wave detectors.

Decline eccentric squats increases patellar tendon loading compared to standard eccentric squats.

Science.gov (United States)

Kongsgaard, M; Aagaard, P; Roikjaer, S; Olsen, D; Jensen, M; Langberg, H; Magnusson, S P

2006-08-01

Recent studies have shown excellent clinical results using eccentric squat training on a 25 degrees decline board to treat patellar tendinopathy. It remains unknown why therapeutic management of patellar tendinopathy using decline eccentric squats offer superior clinical efficacy compared to standard horizontal eccentric squats. This study aimed to compare electromyography activity, patellar tendon strain and joint angle kinematics during standard and decline eccentric squats. Thirteen subjects performed unilateral eccentric squats on flat-and a 25 degrees decline surface. During the squats, electromyography activity was obtained in eight representative muscles. Also, ankle, knee and hip joint goniometry was obtained. Additionally, patellar tendon strain was measured in vivo using ultrasonography as subjects maintained a unilateral isometric 90 degrees knee angle squat position on either flat or 25 degrees decline surface. Patellar tendon strain was significantly greater (Psquat position on the decline surface compared to the standard surface. The stop angles of the ankle and hip joints were significantly smaller during the decline compared to the standard squats (Psquats (Psquats. The use of a 25 degrees decline board increases the load and the strain of the patellar tendon during unilateral eccentric squats. This finding likely explains previous reports of superior clinical efficacy of decline eccentric squats in the rehabilitative management of patellar tendinopathy.

The formation of eccentric compact binary inspirals and the role of gravitational wave emission in binary-single stellar encounters

International Nuclear Information System (INIS)

Samsing, Johan; MacLeod, Morgan; Ramirez-Ruiz, Enrico

2014-01-01

The inspiral and merger of eccentric binaries leads to gravitational waveforms distinct from those generated by circularly merging binaries. Dynamical environments can assemble binaries with high eccentricity and peak frequencies within the LIGO band. In this paper, we study binary-single stellar scatterings occurring in dense stellar systems as a source of eccentrically inspiraling binaries. Many interactions between compact binaries and single objects are characterized by chaotic resonances in which the binary-single system undergoes many exchanges before reaching a final state. During these chaotic resonances, a pair of objects has a non-negligible probability of experiencing a very close passage. Significant orbital energy and angular momentum are carried away from the system by gravitational wave (GW) radiation in these close passages, and in some cases this implies an inspiral time shorter than the orbital period of the bound third body. We derive the cross section for such dynamical inspiral outcomes through analytical arguments and through numerical scattering experiments including GW losses. We show that the cross section for dynamical inspirals grows with increasing target binary semi-major axis a and that for equal-mass binaries it scales as a 2/7 . Thus, we expect wide target binaries to predominantly contribute to the production of these relativistic outcomes. We estimate that eccentric inspirals account for approximately 1% of dynamically assembled non-eccentric merging binaries. While these events are rare, we show that binary-single scatterings are a more effective formation channel than single-single captures for the production of eccentrically inspiraling binaries, even given modest binary fractions.

Virtual Proprioception for eccentric training.

Science.gov (United States)

LeMoyne, Robert; Mastroianni, Timothy

2017-07-01

Wireless inertial sensors enable quantified feedback, which can be applied to evaluate the efficacy of therapy and rehabilitation. In particular eccentric training promotes a beneficial rehabilitation and strength training strategy. Virtual Proprioception for eccentric training applies real-time feedback from a wireless gyroscope platform enabled through a software application for a smartphone. Virtual Proprioception for eccentric training is applied to the eccentric phase of a biceps brachii strength training and contrasted to a biceps brachii strength training scenario without feedback. During the operation of Virtual Proprioception for eccentric training the intent is to not exceed a prescribed gyroscope signal threshold based on the real-time presentation of the gyroscope signal, in order to promote the eccentric aspect of the strength training endeavor. The experimental trial data is transmitted wireless through connectivity to the Internet as an email attachment for remote post-processing. A feature set is derived from the gyroscope signal for machine learning classification of the two scenarios of Virtual Proprioception real-time feedback for eccentric training and eccentric training without feedback. Considerable classification accuracy is achieved through the application of a multilayer perceptron neural network for distinguishing between the Virtual Proprioception real-time feedback for eccentric training and eccentric training without feedback.

Stability of hierarchical triples - I. Dependence on inner eccentricity and inclination

Science.gov (United States)

Mylläri, A.; Valtonen, M.; Pasechnik, A.; Mikkola, S.

2018-05-01

In simulations it is often important to decide if a given hierarchical triple star system is stable over an extended period of time. We introduce a stability criterion, modified from earlier work, where we use the closest approach ratio Q of the third star to the inner binary centre of mass in their initial osculating orbits. We study by numerical integration the orbits of over 1000 000 triple systems of the fixed masses and outer eccentricities eout, but varying inner eccentricities ein and inclinations i. 12 primary combinations of masses have been tried, representing the range encountered in stellar systems. The definition of the instability is either the escape of one of the bodies, or the exchange of the members between the inner and outer systems. An analytical approximation is derived using the energy change in a single close encounter between the inner and outer systems, assuming that the orbital phases in subsequent encounters occur randomly. The theory provides a fairly good description of the typical Qst, the smallest Q value that allows the system to be stable over N = 10 000 revolutions of the initial outer orbit. The final stability limit formula is Qst = 101/3A[( f g)2/(1 - eout)]1/6, where the coefficient A ˜ 1 should be used in N-body experiments, and A = 2.4 when the absolute long-term stability is required. The functions f (ein, cos i) and g(m1, m2, m3) are derived in the paper. At the limit of ein = i = m3 = 0, f g = 1.

GMRT Discovery of A Millisecond Pulsar in a Very Eccentric Binary System

OpenAIRE

Freire, Paulo C.; Gupta, Yashwant; Ransom, Scott M.; Ishwara-Chandra, C. H.

2004-01-01

We report the discovery of the binary millisecond pulsar J0514-4002A, which is the first known pulsar in the globular cluster NGC 1851 and the first pulsar discovered using the Giant Metrewave Radio Telescope (GMRT). The pulsar has a rotational period of 4.99 ms, an orbital period of 18.8 days, and the most eccentric pulsar orbit yet measured (e = 0.89). The companion has a minimum mass of 0.9 M_sun and its nature is presently unclear. After accreting matter from a low-mass companion star whi...

Projectile Motion in the "Language" of Orbital Motion

Science.gov (United States)

Zurcher, Ulrich

2011-01-01

We consider the orbit of projectiles launched with arbitrary speeds from the Earth's surface. This is a generalization of Newton's discussion about the transition from parabolic to circular orbits, when the launch speed approaches the value [image omitted]. We find the range for arbitrary launch speeds and angles, and calculate the eccentricity of…

Validation of Galileo orbits using SLR with a focus on satellites launched into incorrect orbital planes

Science.gov (United States)

Sośnica, Krzysztof; Prange, Lars; Kaźmierski, Kamil; Bury, Grzegorz; Drożdżewski, Mateusz; Zajdel, Radosław; Hadas, Tomasz

2018-02-01

The space segment of the European Global Navigation Satellite System (GNSS) Galileo consists of In-Orbit Validation (IOV) and Full Operational Capability (FOC) spacecraft. The first pair of FOC satellites was launched into an incorrect, highly eccentric orbital plane with a lower than nominal inclination angle. All Galileo satellites are equipped with satellite laser ranging (SLR) retroreflectors which allow, for example, for the assessment of the orbit quality or for the SLR-GNSS co-location in space. The number of SLR observations to Galileo satellites has been continuously increasing thanks to a series of intensive campaigns devoted to SLR tracking of GNSS satellites initiated by the International Laser Ranging Service. This paper assesses systematic effects and quality of Galileo orbits using SLR data with a main focus on Galileo satellites launched into incorrect orbits. We compare the SLR observations with respect to microwave-based Galileo orbits generated by the Center for Orbit Determination in Europe (CODE) in the framework of the International GNSS Service Multi-GNSS Experiment for the period 2014.0-2016.5. We analyze the SLR signature effect, which is characterized by the dependency of SLR residuals with respect to various incidence angles of laser beams for stations equipped with single-photon and multi-photon detectors. Surprisingly, the CODE orbit quality of satellites in the incorrect orbital planes is not worse than that of nominal FOC and IOV orbits. The RMS of SLR residuals is even lower by 5.0 and 1.5 mm for satellites in the incorrect orbital planes than for FOC and IOV satellites, respectively. The mean SLR offsets equal -44.9, -35.0, and -22.4 mm for IOV, FOC, and satellites in the incorrect orbital plane. Finally, we found that the empirical orbit models, which were originally designed for precise orbit determination of GNSS satellites in circular orbits, provide fully appropriate results also for highly eccentric orbits with variable linear

Early Paleogene Orbital Variations in Atmospheric CO2 and New Astronomical Solutions

Science.gov (United States)

Zeebe, R. E.

2017-12-01

Geologic records across the globe show prominent variations on orbital time scales during numerous epochs going back hundreds of millions of years. The origin of the Milankovic cycles are variations in orbital parameters of the bodies of the Solar System. On long time scales, the orbital variations can not be computed analytically because of the chaotic nature of the Solar System. Thus, numerical solutions are used to estimate changes in, e.g., Earth's orbital parameters in the past. The orbital solutions represent the backbone of cyclostratigraphy and astrochronology, now widely used in geology and paleoclimatology. Hitherto only two solutions for Earth's eccentricity appear to be used in paleoclimate studies, provided by two different groups that integrated the full Solar System equations over the past >100 Myr. In this presentation, I will touch on the basic physics behind, and present new results of, accurate Solar System integrations for Earth's eccentricity over the past hundred million years. I will discuss various limitations within the framework of the present simulations and compare the results to existing solutions. Furthermore, I will present new results from practical applications of such orbital solutions, including effects of orbital forcing on coupled climate- and carbon cycle variations. For instance, we have recently revealed a mechanism for a large lag between changes in carbon isotope ratios and eccentricity at the 400-kyr period, which has been observed in Paleocene, Oligocene, and Miocene sections. Finally, I will present the first estimates of orbital-scale variations in atmospheric CO2 during the early Paleogene.

Orbits in weak and strong bars

CERN Document Server

Contopoulos, George

1980-01-01

The authors study the plane orbits in simple bar models embedded in an axisymmetric background when the bar density is about 1% (weak), 10% (intermediate) or 100% (strong bar) of the axisymmetric density. Most orbits follow the stable periodic orbits. The basic families of periodic orbits are described. In weak bars with two Inner Lindblad Resonances there is a family of stable orbits extending from the center up to the Outer Lindblad Resonance. This family contains the long period orbits near corotation. Other stable families appear between the Inner Lindblad Resonances, outside the Outer Lindblad Resonance, around corotation (short period orbits) and around the center (retrograde). Some families become unstable or disappear in strong bars. A comparison is made with cases having one or no Inner Lindblad Resonance. (12 refs).

THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. I. MEASURING PHOTOMETRIC ECCENTRICITIES OF INDIVIDUAL TRANSITING PLANETS

International Nuclear Information System (INIS)

Dawson, Rebekah I.; Johnson, John Asher

2012-01-01

Exoplanet orbital eccentricities offer valuable clues about the history of planetary systems. Eccentric, Jupiter-sized planets are particularly interesting: they may link the 'cold' Jupiters beyond the ice line to close-in hot Jupiters, which are unlikely to have formed in situ. To date, eccentricities of individual transiting planets primarily come from radial-velocity measurements. Kepler has discovered hundreds of transiting Jupiters spanning a range of periods, but the faintness of the host stars precludes radial-velocity follow-up of most. Here, we demonstrate a Bayesian method of measuring an individual planet's eccentricity solely from its transit light curve using prior knowledge of its host star's density. We show that eccentric Jupiters are readily identified by their short ingress/egress/total transit durations—part of the 'photoeccentric' light curve signature of a planet's eccentricity—even with long-cadence Kepler photometry and loosely constrained stellar parameters. A Markov Chain Monte Carlo exploration of parameter posteriors naturally marginalizes over the periapse angle and automatically accounts for the transit probability. To demonstrate, we use three published transit light curves of HD 17156 b to measure an eccentricity of e = 0.71 +0.16 –0.09 , in good agreement with the discovery value e = 0.67 ± 0.08 based on 33 radial-velocity measurements. We present two additional tests using Kepler data. In each case, the technique proves to be a viable method of measuring exoplanet eccentricities and their confidence intervals. Finally, we argue that this method is the most efficient, effective means of identifying the extremely eccentric, proto-hot Jupiters predicted by Socrates et al.

Eccentric exercise

DEFF Research Database (Denmark)

Kjaer, Michael; Heinemeier, Katja Maria

2014-01-01

to differences in type and/or amount of mechanical stimulus with regard to expression of collagen, regulatory factors for collagen, and cross-link regulators. In overused (tendinopathic) human tendon, eccentric exercise training has a beneficial effect, but the mechanism by which this is elicited is unknown......Eccentric exercise can influence tendon mechanical properties and matrix protein synthesis. mRNA for collagen and regulatory factors thereof are upregulated in animal tendons, independent of muscular contraction type, supporting the view that tendon, compared with skeletal muscle, is less sensitive......, and slow concentric loading appears to have similar beneficial effects. It may be that tendinopathic regions, as long as they are subjected to a certain magnitude of load at a slow speed, independent of whether this is eccentric or concentric in nature, can reestablish their normal tendon fibril alignment...

Applying KAM Theory to Highly Eccentric Orbits

Science.gov (United States)

2014-03-27

tingly committing a couple blunders, Kepler published Astronomia Nova ΑΙΤΙΟΛΟΓΣΤΟΣ seu physica coelestis, tradita commentariis de motibus stellae...to explain that this parameter is typically determined by the size of mass ratios, which for the solar system dynamics can be relatively big when... super efficient, refined code and lots of run time. Even in this particular test case, there may be problems/limitations with the larger orbits. It

Decline eccentric squats increases patellar tendon loading compared to standard eccentric squats

DEFF Research Database (Denmark)

Kongsgaard, M; Aagaard, P; Roikjaer, S

2006-01-01

Recent studies have shown excellent clinical results using eccentric squat training on a 25 degrees decline board to treat patellar tendinopathy. It remains unknown why therapeutic management of patellar tendinopathy using decline eccentric squats offer superior clinical efficacy compared...

Popliteal versus tibial retrograde access for subintimal arterial flossing with antegrade-retrograde intervention (SAFARI) technique.

Science.gov (United States)

Hua, W R; Yi, M Q; Min, T L; Feng, S N; Xuan, L Z; Xing, J

2013-08-01

This study aimed to ascertain differences in benefit and effectiveness of popliteal versus tibial retrograde access in subintimal arterial flossing with the antegrade-retrograde intervention (SAFARI) technique. This was a retrospective study of SAFARI-assisted stenting for long chronic total occlusion (CTO) of TASC C and D superficial femoral lesions. 38 cases had superficial femoral artery lesions (23 TASC C and 15 TASC D). All 38 cases underwent SAFARI-assisted stenting. The ipsilateral popliteal artery was retrogradely punctured in 17 patients. A distal posterior tibial (PT) or dorsalis pedis (DP) artery was retrogradely punctured in 21 patients, and 16 of them were punctured after open surgical exposure. SAFARI technical success was achieved in all cases. There was no significant difference in 1-year primary patency (75% vs. 78.9%, p = .86), secondary patency (81.2% vs. 84.2%, p = .91) and access complications (p = 1.00) between popliteal and tibial retrograde access. There was statistical difference in operation time between popliteal (140.1 ± 28.4 min) and tibial retrograde access with PT/DP punctures after surgical vessel exposure (120.4 ± 23.0 min, p = .04). The SAFARI technique is a safe and feasible option for patients with infrainguinal CTO (TASC II C and D). The PT or DP as the retrograde access after surgical vessel exposure is a good choice when using the SAFARI technique. Copyright © 2013 European Society for Vascular Surgery. Published by Elsevier Ltd. All rights reserved.

Effect of spaceflight on the spatial orientation of the vestibulo-ocular reflex during eccentric roll rotation: A case report.

Science.gov (United States)

Reschke, Millard F; Wood, Scott J; Clément, Gilles

2018-01-01

Ground-based studies have reported shifts of the vestibulo-ocular reflex (VOR) slow phase velocity (SPV) axis toward the resultant gravito-inertial force vector. The VOR was examined during eccentric roll rotation before, during and after an 8-day orbital mission. On orbit this vector is aligned with the head z-axis. Our hypothesis was that eccentric roll rotation on orbit would generate horizontal eye movements. Two subjects were rotated in a semi-supine position with the head nasal-occipital axis parallel to the axis of rotation and 0.5 m off-center. The chair accelerated at 120 deg/s2 to 120 deg/s, rotated at constant velocity for one minute, and then decelerated to a stop in similar fashion. On Earth, the stimulation primarily generated torsional VOR. During spaceflight, in one subject torsional VOR became horizontal VOR, and then decayed very slowly. In the other subject, torsional VOR was reduced on orbit relative to pre- and post-flight, but the SPV axis did not rotate. We attribute the shift from torsional to horizontal VOR on orbit to a spatial orientation of velocity storage toward alignment with the gravito-inertial force vector, and the inter-individual difference to cognitive factors related to the subjective straight-ahead.

Geosynchronous inclined orbits for high-latitude communications

Science.gov (United States)

Fantino, E.; Flores, R. M.; Di Carlo, M.; Di Salvo, A.; Cabot, E.

2017-11-01

We present and discuss a solution to the growing demand for satellite telecommunication coverage in the high-latitude geographical regions (beyond 55°N), where the signal from geostationary satellites is limited or unavailable. We focus on the dynamical issues associated to the design, the coverage, the maintenance and the disposal of a set of orbits selected for the purpose. Specifically, we identify a group of highly inclined, moderately eccentric geosynchronous orbits derived from the Tundra orbit (geosynchronous, eccentric and critically inclined). Continuous coverage can be guaranteed by a constellation of three satellites in equally spaced planes and suitably phased. By means of a high-precision model of the terrestrial gravity field and the relevant environmental perturbations, we study the evolution of these orbits. The effects of the different perturbations on the ground track (which is more important for coverage than the orbital elements themselves) are isolated and analyzed. The physical model and the numerical setup are optimized with respect to computing time and accuracy. We show that, in order to maintain the ground track unchanged, the key parameters are the orbital period and the argument of perigee. Furthermore, corrections to the right ascension of the ascending node are needed in order to preserve the relative orientation of the orbital planes. A station-keeping strategy that minimizes propellant consumption is then devised, and comparisons are made between the cost of a solution based on impulsive maneuvers and one with continuous thrust. Finally, the issue of end-of-life disposal is discussed.

Retrograde pulmonary arteriography

International Nuclear Information System (INIS)

Calcaterra, G.; Lam, J.; Losekoot, T.G.

1984-01-01

The authors performed retrograde pulmonary arteriography by means of a pulmonary venous wedge injection in 10 patients with no demonstrable intrapericardial pulmonary arteries by 'conventional' angiographic techniques. In all cases but one, the procedure demonstrated the feasibility of a further operation. No complications were observed. Retrograde pulmonary arteriography is an important additional method for determining the existence of surgically accessible pulmonary arteries when other techniques have failed. (Auth.)

Thermal-orbital coupled tidal heating and habitability of Martian-sized extrasolar planets around M stars

International Nuclear Information System (INIS)

Shoji, D.; Kurita, K.

2014-01-01

M-type stars are good targets in the search for habitable extrasolar planets. Due to their low effective temperatures, the habitable zone of M stars is very close to the stars themselves. For planets that are close to their stars, tidal heating plays an important role in thermal and orbital evolutions, especially when the planet's orbit has a relatively large eccentricity. Although tidal heating interacts with the thermal state and the orbit of the planet, such coupled calculations for extrasolar planets around M stars have not been conducted. We perform coupled calculations using simple structural and orbital models and analyze the thermal state and habitability of a terrestrial planet. Considering this planet to be Martian-sized, the tide heats up and partially melts the mantle, maintaining an equilibrium state if the mass of the star is less than 0.2 times the mass of the Sun and the initial eccentricity of the orbit is more than 0.2. The reduction of heat dissipation due to the melted mantle allows the planet to stay in the habitable zone for more than 10 Gyr even though the orbital distance is small. The surface heat flux at the equilibrium state is between that of Mars and Io. The thermal state of the planet mainly depends on the initial value of the eccentricity and the mass of the star.

Thermal-orbital coupled tidal heating and habitability of Martian-sized extrasolar planets around M stars

Energy Technology Data Exchange (ETDEWEB)

Shoji, D.; Kurita, K. [Earthquake Research Institute, University of Tokyo, Tokyo (Japan)

2014-07-01

M-type stars are good targets in the search for habitable extrasolar planets. Due to their low effective temperatures, the habitable zone of M stars is very close to the stars themselves. For planets that are close to their stars, tidal heating plays an important role in thermal and orbital evolutions, especially when the planet's orbit has a relatively large eccentricity. Although tidal heating interacts with the thermal state and the orbit of the planet, such coupled calculations for extrasolar planets around M stars have not been conducted. We perform coupled calculations using simple structural and orbital models and analyze the thermal state and habitability of a terrestrial planet. Considering this planet to be Martian-sized, the tide heats up and partially melts the mantle, maintaining an equilibrium state if the mass of the star is less than 0.2 times the mass of the Sun and the initial eccentricity of the orbit is more than 0.2. The reduction of heat dissipation due to the melted mantle allows the planet to stay in the habitable zone for more than 10 Gyr even though the orbital distance is small. The surface heat flux at the equilibrium state is between that of Mars and Io. The thermal state of the planet mainly depends on the initial value of the eccentricity and the mass of the star.

Dynamics of Pluto and Charon

International Nuclear Information System (INIS)

Dobrovolskis, A.R.

1989-01-01

The dynamics of the Pluto-Charon system are reviewed from a historical perspective. Although Pluto's orbit crosses Neptune's, an intricate system of nested resonances keeps these planets apart. Pluto's orbit is apparently chaotic as well. Pluto always keeps the same face turned toward Charon, and vice versa. Tides also damp Charon's orbital eccentricity and inclination. Precession of Pluto's orbital plane causes Pluto's obliquity to vary periodically from formally prograde to retrograde. Pluto is probably an original member of the Solar system, but not an escape satellite of Neptune. The Voyager II encounter with Neptune, the final Pluto-Charon mutual events, and the next generation of telescopes are bound to reveal some surprises

Retrograde curves of solidus and solubility

International Nuclear Information System (INIS)

Vasil'ev, M.V.

1979-01-01

The investigation was concerned with the constitutional diagrams of the eutectic type with ''retrograde solidus'' and ''retrograde solubility curve'' which must be considered as diagrams with degenerate monotectic transformation. The solidus and the solubility curves form a retrograde curve with a common retrograde point representing the solubility maximum. The two branches of the Aetrograde curve can be described with the aid of two similar equations. Presented are corresponding equations for the Cd-Zn system and shown is the possibility of predicting the run of the solubility curve

Constraining stellar binary black hole formation scenarios with eLISA eccentricity measurements

Science.gov (United States)

Nishizawa, Atsushi; Sesana, Alberto; Berti, Emanuele; Klein, Antoine

2017-03-01

A space-based interferometer such as the evolved Laser Interferometer Space Antenna (eLISA) could observe a few to a few thousands of progenitors of black hole binaries (BHBs) similar to those recently detected by Advanced LIGO. Gravitational radiation circularizes the orbit during inspiral, but some BHBs retain a measurable eccentricity at the low frequencies where eLISA is the most sensitive. The eccentricity of a BHB carries precious information about its formation channel: BHBs formed in the field, in globular clusters, or close to a massive black hole (MBH) have distinct eccentricity distributions in the eLISA band. We generate mock eLISA observations, folding in measurement errors, and using a Bayesian model selection, we study whether eLISA measurements can identify the BHB formation channel. We find that a handful of observations would suffice to tell whether BHBs were formed in the gravitational field of an MBH. Conversely, several tens of observations are needed to tell apart field formation from globular cluster formation. A 5-yr eLISA mission with the longest possible armlength is desirable to shed light on BHB formation scenarios.

An unusual combination of Unilateral Orbital Plexiform Neurofibroma in a patient with oculocutaneous albinism

Directory of Open Access Journals (Sweden)

J Saravanan

2014-01-01

Full Text Available A 70-year-old female patient presented with proptosis of right eye for the past 15 days and defective vision in both eyes since birth. She was found to have eccentric painful proptosis of right eye along with features of oculocutaneous albinism. Eccentric proptosis was due to an orbital mass which proved to be a plexiform neurofibroma by histopathological examination. The case is presented for its rarity, as an isolated orbital plexiform neurofibroma without the systemic features of neurofibromatosis is rare and its coincidental presentation with oculocutaneous albinism is yet rare and has not been reported so far.

Spectroscopic orbit for HDE 245770 A0535+26

International Nuclear Information System (INIS)

Hutchings, J.B.

1984-01-01

Optical spectroscopic data are examined using the X-ray intensity period of 111 days. Optical and X-ray pulse-timing orbit parameters agree well and indicate an eccentricity of approximately 0.3. Masses of the stars and periastron effects are discussed. 6 references

M2K. II. A TRIPLE-PLANET SYSTEM ORBITING HIP 57274

Energy Technology Data Exchange (ETDEWEB)

Fischer, Debra A.; Giguere, Matthew J.; Moriarty, John; Brewer, John; Spronck, Julien F. P.; Schwab, Christian; Szymkowiak, Andrew [Department of Astronomy, Yale University, New Haven, CT 06511 (United States); Gaidos, Eric [Department of Geology and Geophysics, University of Hawaii, Honolulu, HI 96822 (United States); Howard, Andrew W.; Marcy, Geoffrey W. [Department of Astronomy, University of California at Berkeley, Berkeley, CA 94720 (United States); Johnson, John A. [Department of Astronomy, California Institute of Technology, Pasadena, CA 91125 (United States); Wright, Jason T. [Center for Exoplanets and Habitable Worlds, 525 Davey Lab, The Pennsylvania State University, University Park, PA 16803 (United States); Valenti, Jeff A. [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Piskunov, Nikolai [Department of Astronomy and Space Physics, Uppsala University, Box 515, 751 20 Uppsala (Sweden); Clubb, Kelsey I.; Isaacson, Howard [Pufendorf Institute for Advanced Studies, Lund University, Lund (Sweden); Apps, Kevin [75B Cheyne Walk, Surrey RH6 7LR (United Kingdom); Lepine, Sebastien [American Museum of Natural History, New York, NY 10023 (United States); Mann, Andrew, E-mail: debra.fischer@yale.edu [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States)

2012-01-20

Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with Msin i = 11.6 M{sub Circled-Plus} (0.036 M{sub Jup}), an orbital period of 8.135 {+-} 0.004 days, and slightly eccentric orbit e = 0.19 {+-} 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has Msin i = 0.4 M{sub Jup} with an orbital period of 32.0 {+-} 0.02 days in a nearly circular orbit (e = 0.05 {+-} 0.03). The third planet has Msin i = 0.53 M{sub Jup} with an orbital period of 432 {+-} 8 days (1.18 years) and an eccentricity e = 0.23 {+-} 0.03. This discovery adds to the number of super-Earth mass planets with M sin i < 12 M{sub Circled-Plus} that have been detected with Doppler surveys. We find that 56% {+-} 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% {+-} 8%, that are members of Doppler-detected, multi-planet systems.

M2K. II. A TRIPLE-PLANET SYSTEM ORBITING HIP 57274

International Nuclear Information System (INIS)

Fischer, Debra A.; Giguere, Matthew J.; Moriarty, John; Brewer, John; Spronck, Julien F. P.; Schwab, Christian; Szymkowiak, Andrew; Gaidos, Eric; Howard, Andrew W.; Marcy, Geoffrey W.; Johnson, John A.; Wright, Jason T.; Valenti, Jeff A.; Piskunov, Nikolai; Clubb, Kelsey I.; Isaacson, Howard; Apps, Kevin; Lepine, Sebastien; Mann, Andrew

2012-01-01

Doppler observations from Keck Observatory have revealed a triple-planet system orbiting the nearby K4V star, HIP 57274. The inner planet, HIP 57274b, is a super-Earth with Msin i = 11.6 M ⊕ (0.036 M Jup ), an orbital period of 8.135 ± 0.004 days, and slightly eccentric orbit e = 0.19 ± 0.1. We calculate a transit probability of 6.5% for the inner planet. The second planet has Msin i = 0.4 M Jup with an orbital period of 32.0 ± 0.02 days in a nearly circular orbit (e = 0.05 ± 0.03). The third planet has Msin i = 0.53 M Jup with an orbital period of 432 ± 8 days (1.18 years) and an eccentricity e = 0.23 ± 0.03. This discovery adds to the number of super-Earth mass planets with M sin i ⊕ that have been detected with Doppler surveys. We find that 56% ± 18% of super-Earths are members of multi-planet systems. This is certainly a lower limit because of observational detectability limits, yet significantly higher than the fraction of Jupiter mass exoplanets, 20% ± 8%, that are members of Doppler-detected, multi-planet systems.

Tidal Heating of Earth-like Exoplanets around M Stars: Thermal, Magnetic, and Orbital Evolutions.

Science.gov (United States)

Driscoll, P E; Barnes, R

2015-09-01

The internal thermal and magnetic evolution of rocky exoplanets is critical to their habitability. We focus on the thermal-orbital evolution of Earth-mass planets around low-mass M stars whose radiative habitable zone overlaps with the "tidal zone," where tidal dissipation is expected to be a significant heat source in the interior. We develop a thermal-orbital evolution model calibrated to Earth that couples tidal dissipation, with a temperature-dependent Maxwell rheology, to orbital circularization and migration. We illustrate thermal-orbital steady states where surface heat flow is balanced by tidal dissipation and cooling can be stalled for billions of years until circularization occurs. Orbital energy dissipated as tidal heat in the interior drives both inward migration and circularization, with a circularization time that is inversely proportional to the dissipation rate. We identify a peak in the internal dissipation rate as the mantle passes through a viscoelastic state at mantle temperatures near 1800 K. Planets orbiting a 0.1 solar-mass star within 0.07 AU circularize before 10 Gyr, independent of initial eccentricity. Once circular, these planets cool monotonically and maintain dynamos similar to that of Earth. Planets forced into eccentric orbits can experience a super-cooling of the core and rapid core solidification, inhibiting dynamo action for planets in the habitable zone. We find that tidal heating is insignificant in the habitable zone around 0.45 (or larger) solar-mass stars because tidal dissipation is a stronger function of orbital distance than stellar mass, and the habitable zone is farther from larger stars. Suppression of the planetary magnetic field exposes the atmosphere to stellar wind erosion and the surface to harmful radiation. In addition to weak magnetic fields, massive melt eruption rates and prolonged magma oceans may render eccentric planets in the habitable zone of low-mass stars inhospitable for life.

WIYN Open Cluster Study: Binary Orbits and Tidal Circularization in NGC 6819

Science.gov (United States)

Morscher, Meagan B.; Mathieu, R. D.; Kaeppler, S.; Hole, K. T.; Meibom, S.

2006-12-01

We are conducting a comprehensive stellar radial-velocity survey in NGC 6819, a rich, intermediate age ( 2.4 Gyr) open cluster with [Fe/H] -0.05. As of October 2006, we have obtained 7065 radial-velocity measurements of 1409 stars using the WIYN Hydra Multi-Object Spectrograph, with typical velocity measurement precisions of 0.4 km/s. Using an E/I criterion of 3, we have identified 282 velocity variables. In the past year we have expanded the number of final orbital solutions by 45 to a total of more than 80 solutions. In coeval stellar populations, circular binaries tend to have the shortest orbital periods, while longer period binaries show a distribution of non-zero eccentricities. The circularization of the shortest period orbits is the result of an exchange of stellar and orbital angular momentum due to tidal interactions. We defined a population’s tidal circularization period as the longest orbital period at which a binary of typical initial eccentricity has become circularized (e.g., has evolved to an eccentricity e = 0.01) over the lifetime of the cluster (Meibom & Mathieu, 2005, ApJ, 620, 970). We are studying the trend of increasing tidal circularization periods with population age. Preliminary results in NGC 6819 indicate a tidal circularization period of 7.5 days, which is consistent with this overall trend. We will recalculate the tidal circularization period in order to include the latest sample of orbital solutions. This comprehensive survey also allows us to investigate the relative spatial distributions of spectroscopic binaries and other constant-velocity cluster members of similar mass. We find the spectroscopic binaries to be more centrally concentrated at a statistically significant level, which we attribute to energy equipartition processes. MM was supported by REU NSF grant AST-0453442. RDM, SK, KTH, and SM were supported by NSF grant AST-0406615.

THE PHOTOECCENTRIC EFFECT AND PROTO-HOT JUPITERS. II. KOI-1474.01, A CANDIDATE ECCENTRIC PLANET PERTURBED BY AN UNSEEN COMPANION

Energy Technology Data Exchange (ETDEWEB)

Dawson, Rebekah I.; Murray-Clay, Ruth A. [Harvard-Smithsonian Center for Astrophysics, 60 Garden St, MS-10, Cambridge, MA 02138 (United States); Johnson, John Asher; Morton, Timothy D. [Department of Astronomy, California Institute of Technology, 1200 East California Boulevard, MC 249-17, Pasadena, CA 91125 (United States); Crepp, Justin R. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Fabrycky, Daniel C. [Department of Astronomy and Astrophysics, University of California Santa Cruz, Santa Cruz, California 95064 (United States); Howard, Andrew W., E-mail: rdawson@cfa.harvard.edu [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822-1839 (United States)

2012-12-20

The exoplanets known as hot Jupiters-Jupiter-sized planets with periods of less than 10 days-likely are relics of dynamical processes that shape all planetary system architectures. Socrates et al. argued that high eccentricity migration (HEM) mechanisms proposed for situating these close-in planets should produce an observable population of highly eccentric proto-hot Jupiters that have not yet tidally circularized. HEM should also create failed-hot Jupiters, with periapses just beyond the influence of fast circularization. Using the technique we previously presented for measuring eccentricities from photometry (the ''photoeccentric effect''), we are distilling a collection of eccentric proto- and failed-hot Jupiters from the Kepler Objects of Interest (KOI). Here, we present the first, KOI-1474.01, which has a long orbital period (69.7340 days) and a large eccentricity e 0.81{sup +0.10}{sub -0.07}, skirting the proto-hot Jupiter boundary. Combining Kepler photometry, ground-based spectroscopy, and stellar evolution models, we characterize host KOI-1474 as a rapidly rotating F star. Statistical arguments reveal that the transiting candidate has a low false-positive probability of 3.1%. KOI-1474.01 also exhibits transit-timing variations of the order of an hour. We explore characteristics of the third-body perturber, which is possibly the ''smoking-gun'' cause of KOI-1474.01's large eccentricity. We use the host star's period, radius, and projected rotational velocity to measure the inclination of the stellar spin. Comparing KOI 1474.01's inclination, we find that its orbit is marginally consistent with being aligned with the stellar spin axis, although a reanalysis is warranted with future additional data. Finally, we discuss how the number and existence of proto-hot Jupiters will not only demonstrate that hot Jupiters migrate via HEM, but also shed light on the typical timescale for the mechanism.

Addressing the statistical mechanics of planet orbits in the solar system

Science.gov (United States)

Mogavero, Federico

2017-10-01

The chaotic nature of planet dynamics in the solar system suggests the relevance of a statistical approach to planetary orbits. In such a statistical description, the time-dependent position and velocity of the planets are replaced by the probability density function (PDF) of their orbital elements. It is natural to set up this kind of approach in the framework of statistical mechanics. In the present paper, I focus on the collisionless excitation of eccentricities and inclinations via gravitational interactions in a planetary system. The future planet trajectories in the solar system constitute the prototype of this kind of dynamics. I thus address the statistical mechanics of the solar system planet orbits and try to reproduce the PDFs numerically constructed by Laskar (2008, Icarus, 196, 1). I show that the microcanonical ensemble of the Laplace-Lagrange theory accurately reproduces the statistics of the giant planet orbits. To model the inner planets I then investigate the ansatz of equiprobability in the phase space constrained by the secular integrals of motion. The eccentricity and inclination PDFs of Earth and Venus are reproduced with no free parameters. Within the limitations of a stationary model, the predictions also show a reasonable agreement with Mars PDFs and that of Mercury inclination. The eccentricity of Mercury demands in contrast a deeper analysis. I finally revisit the random walk approach of Laskar to the time dependence of the inner planet PDFs. Such a statistical theory could be combined with direct numerical simulations of planet trajectories in the context of planet formation, which is likely to be a chaotic process.

Orbitally forced sedimentary rhythms in the stratigraphic record: is there room for tidal forcing?

NARCIS (Netherlands)

Boer, P.L. de; Trabucho Alexandre, J.

2011-01-01

The imprint of orbital cycles, which result from the varying eccentricity of the Earth’s orbit and changes in the orientation of its axis, have been recognised throughout the Phanerozoic rock record. Variations in insolation and their effect on climate are generally considered to be the sole

Long-term evaluation of orbital dynamics in the Sun-planet system considering axial-tilt

Science.gov (United States)

Bakhtiari, Majid; Daneshjou, Kamran

2018-05-01

In this paper, the axial-tilt (obliquity) effect of planets on the motion of planets’ orbiter in prolonged space missions has been investigated in the presence of the Sun gravity. The proposed model is based on non-simplified perturbed dynamic equations of planetary orbiter motion. From a new point of view, in this work, the dynamic equations regarding a disturbing body in elliptic inclined three-dimensional orbit are derived. The accuracy of this non-simplified method is validated with dual-averaged method employed on a generalized Earth-Moon system. It is shown that the neglected short-time oscillations in dual-averaged technique can accumulate and propel to remarkable errors in the prolonged evolution. After validation, the effects of the planet’s axial-tilt on eccentricity, inclination and right ascension of the ascending node of the orbiter are investigated. Moreover, a generalized model is provided to study the effects of third-body inclination and eccentricity on orbit characteristics. It is shown that the planet’s axial-tilt is the key to facilitating some significant changes in orbital elements in long-term mission and short-time oscillations must be considered in accurate prolonged evaluation.

Periodic orbits near the particle resonance in galaxies

CERN Document Server

Contopoulos, George

1978-01-01

Near the particle resonance of a spiral galaxy the almost circular periodic orbits that exist inside the resonance (direct) or outside it (retrograde) are replaced by elongated trapped orbits around the maxima of the potential L/sub 4/ and L/sub 5/. These are the long- period trapped periodic orbits. The long-period orbits shrink to the points L/sub 4/, L/sub 5/ for a critical value of the Hamiltonian h. For still larger h, a family of short-period trapped orbits appears, with continuously growing size. The evolution of the periodic orbits with h is followed, theoretically and numerically, from the untrapped orbits to the long-periodic orbits and then to the short-periodic orbits, mainly in the case of a bar. In a tight spiral case an explanation of the asymmetric periodic and banana orbits is given, and an example of short-period orbits not surrounding L/sub 4/ or L/sub 5/ is provided. Another family of periodic orbits reaching corotation is trapped at the inner Lindblad resonance. (5 refs).

High Velocity Spectroscopic Binary Orbits from Photoelectric Radial Velocities: BD+20 5152, a Possible Triple System

Directory of Open Access Journals (Sweden)

Sperauskas J.

2010-12-01

Full Text Available The spectroscopic orbit of a high proper motion star, BD+20 5152, is calculated from 34 CORAVEL-type radial velocity measurements. The star has a slightly eccentric orbit with a period of 5.70613 d, half-amplitude of 47.7 km/s and eccentricity of 0.049. The center-of-mass velocity of the system is -24.3 km/s. BD+20 5152 seems to be a triple system consisting of a G8 dwarf as a primary component and of two K6-M0 dwarfs as secondary and tertiary components. This model is based on the analysis of its UBVRI and JHK magnitudes. According to the SuperWASP photometry, spots on the surface of the primary are suspected. The excessive brightness in the Galex FUV and NUV magnitudes and a non-zero eccentricity suggest the age of this system to be less than 1 Gyr.

Eccentric crank variable compression ratio mechanism

Science.gov (United States)

Lawrence, Keith Edward [Kobe, JP; Moser, William Elliott [Peoria, IL; Roozenboom, Stephan Donald [Washington, IL; Knox, Kevin Jay [Peoria, IL

2008-05-13

A variable compression ratio mechanism for an internal combustion engine that has an engine block and a crankshaft is disclosed. The variable compression ratio mechanism has a plurality of eccentric disks configured to support the crankshaft. Each of the plurality of eccentric disks has at least one cylindrical portion annularly surrounded by the engine block. The variable compression ratio mechanism also has at least one actuator configured to rotate the plurality of eccentric disks.

Studies of retrograde memory: A long-term view

OpenAIRE

Warrington, Elizabeth K.

1996-01-01

Studies of retrograde amnesia are reviewed. First, the issues of temporal gradients of retrograde amnesia are discussed. Second, the question of the anatomical substrates of this syndrome are considered. Finally, some evidence for fractionation of different classes of memoranda within the retrograde time period are presented.

Gravitational waveforms from a point particle orbiting a Schwarzschild black hole

International Nuclear Information System (INIS)

Martel, Karl

2004-01-01

We numerically solve the inhomogeneous Zerilli-Moncrief and Regge-Wheeler equations in the time domain. We obtain the gravitational waveforms produced by a point particle of mass μ traveling around a Schwarzschild black hole of mass M on arbitrary bound and unbound orbits. Fluxes of energy and angular momentum at infinity and the event horizon are also calculated. Results for circular orbits, selected cases of eccentric orbits, and parabolic orbits are presented. The numerical results from the time-domain code indicate that, for all three types of orbital motion, black hole absorption contributes less than 1% of the total flux, so long as the orbital radius r p (t) satisfies r p (t)>5M at all times

Retrograde vs. Antegrade Puncture for Infra-Inguinal Angioplasty

International Nuclear Information System (INIS)

Nice, C.; Timmons, G.; Bartholemew, P.; Uberoi, R.

2003-01-01

This study was done to compare antegrade punctures with a retrograde puncture technique for infrainguinal angioplasty. A group of 100 consecutive patients (71 men, 29 women) were randomized for antegrade puncture or retrograde puncture of the common femoral artery. Following retrograde puncture the guidewire was 'turned' and placed into the superficial femoral artery. The time for gaining access, screening time, radiation dose, patient height, weight and complications were recorded. All patients were reviewed the day after the procedure and within 3 months. Data from 46 patients (34 males and 12 females) in the retrograde group and 44 (28 males and 16 females) in the antegrade group were available for analysis. Mean procedure time,screening time, radiation dose, height and weight were 8.3 minutes(range 3-22), 2.1 minutes (0.3-6.5), 7950 mGy cm -2 (820-71250), 169 cm (149-204) and 79 kg (32-108) for retrograde puncture and 8 min (2-60), 0.7 min (0.0-3.2), 1069 mGycm -2 (0-15400), 169 cm (152-186) and 75 kg (39-125) for antegrade punctures, respectively. An average of 1.2 (1-2) punctures was required for retrograde and 1.75 (1-8) for antegrade. Seven small hematomas occurred with antegrade and three for retrograde puncture.Retrograde puncture is technically easier with a tendency to fewer complications but results in a higher radiation dose. This technique should be used in difficult patients at high risk of haematoma formation

Secular Orbit and Spin Variations of Asteroid (16) Psyche

Science.gov (United States)

Bills, B. G.; Park, R. S.; Scott, B.

2016-12-01

The obliquity, or angular separation between spin and orbit poles, of asteroid (16) Psyche is currently 95 degrees. We are interested in knowing how much that angular separation varies, on time scales of 104 to 106 years. To answer that question, we have done several related analyses. On short time scales, the orbital element variations of Psyche are dominated by perturbations from Jupiter. Jupiter's dominance has two basic causes: first is the large mass and relatively close position of Jupiter, and second is a 19:8 mean motion resonance. Jupiter completes 8 orbits in 94.9009 years, while Psyche takes 94.9107 years to complete 19 orbits. As a result of this, all of the orbital elements of Psyche exhibit significant periodic variations, with a 94.9 year period dominating. There are also significant variations at the synodic period, which is 8.628 years, or 1/11 of the resonant period. Over a 1000 year time span, centered on the present, the eccentricity varies from 0.133 to 0.140, and the inclination varies from 2.961 to 3.229 degrees. On longer time scales, the orbital elements of Psyche vary considerably more than that, due to secular perturbations from the planets. The secular variations are modeled as the response of interacting mass rings, rather than point masses. Again, Jupiter is the main perturbing influence on Psyche. The eccentricity and inclination both oscillate, with dominant periods of 18.667 kyr. The range of values seen over a million year time span, is 0.057 to 0.147 for eccentricity, and 0.384 to 4.777 degrees for inclination. Using a recent shape model, and assumption of uniform density, to constrain relevant moments of inertia, we estimate the spin pole precession rate parameter to be 8.53 arcsec/year. The current spin pole is at ecliptic {lon, lat} = { 32, -7} deg, whereas the orbit pole is at {lon, lat} = {60.47, 86.91} deg. The current obliquity is thus 94.3 degree. Using nominal values of the input parameters, the recovered spin pole

Wind accretion in the massive X-ray binary 4U 2206+54: abnormally slow wind and a moderately eccentric orbit

Science.gov (United States)

Ribó, M.; Negueruela, I.; Blay, P.; Torrejón, J. M.; Reig, P.

2006-04-01

Massive X-ray binaries are usually classified by the properties of the donor star in classical, supergiant and Be X-ray binaries, the main difference being the mass transfer mechanism between the two components. The massive X-ray binary 4U 2206+54 does not fit in any of these groups, and deserves a detailed study to understand how the transfer of matter and the accretion on to the compact object take place. To this end we study an IUE spectrum of the donor and obtain a wind terminal velocity (v_∞) of ~350 km s-1, which is abnormally slow for its spectral type. We also analyse here more than 9 years of available RXTE/ASM data. We study the long-term X-ray variability of the source and find it to be similar to that observed in the wind-fed supergiant system Vela X-1, reinforcing the idea that 4U 2206+54 is also a wind-fed system. We find a quasi-period decreasing from ~270 to ~130 d, noticed in previous works but never studied in detail. We discuss possible scenarios for its origin and conclude that long-term quasi-periodic variations in the mass-loss rate of the primary are probably driving such variability in the measured X-ray flux. We obtain an improved orbital period of P_orb=9.5591±0.0007 d with maximum X-ray flux at MJD 51856.6±0.1. Our study of the orbital X-ray variability in the context of wind accretion suggests a moderate eccentricity around 0.15 for this binary system. Moreover, the low value of v_∞ solves the long-standing problem of the relatively high X-ray luminosity for the unevolved nature of the donor, BD +53°2790, which is probably an O9.5 V star. We note that changes in v_∞ and/or the mass-loss rate of the primary alone cannot explain the different patterns displayed by the orbital X-ray variability. We finally emphasize that 4U 2206+54, together with LS 5039, could be part of a new population of wind-fed HMXBs with main sequence donors, the natural progenitors of supergiant X-ray binaries.

Eccentricity from transit photometry

DEFF Research Database (Denmark)

Van Eylen, Vincent; Albrecht, Simon

2015-01-01

and can be described by a Rayleigh distribution with $\\sigma$ = 0.049 $\\pm$ 0.013. This is in full agreement with solar system eccentricities, but in contrast to the eccentricity distributions previously derived for exoplanets from radial velocity studies. Our findings are helpful in identifying which...... (TTVs), and we present some previously unreported TTVs. Finally transit durations help distinguish between false positives and true planets and we use our measurements to confirm six new exoplanets....

Orbital Dynamics of Exomoons During Planet–Planet Scattering

Science.gov (United States)

Hong, Yu-Cian; Lunine, Jonathan I.; Nicholson, Philip; Raymond, Sean N.

2018-04-01

Planet–planet scattering is the leading mechanism to explain the broad eccentricity distribution of observed giant exoplanets. Here we study the orbital stability of primordial giant planet moons in this scenario. We use N-body simulations including realistic oblateness and evolving spin evolution for the giant planets. We find that the vast majority (~80%–90% across all our simulations) of orbital parameter space for moons is destabilized. There is a strong radial dependence, as moons past are systematically removed. Closer-in moons on Galilean-moon-like orbits (system, be captured by another planet, be ejected but still orbiting its free-floating host planet, or survive on heliocentric orbits as "planets." The survival rate of moons increases with the host planet mass but is independent of the planet's final (post-scattering) orbits. Based on our simulations, we predict the existence of an abundant galactic population of free-floating (former) moons.

Stable orbits for lunar landing assistance

Science.gov (United States)

Condoleo, Ennio; Cinelli, Marco; Ortore, Emiliano; Circi, Christian

2017-10-01

To improve lunar landing performances in terms of mission costs, trajectory determination and visibility the use of a single probe located over an assistance orbit around the Moon has been taken into consideration. To this end, the properties of two quasi-circular orbits characterised by a stable behaviour of semi-major axis, eccentricity and inclination have been investigated. The analysis has demonstrated the possibility of using an assistance probe, located over one of these orbits, as a relay satellite between lander and Earth, even in the case of landings on the far side of the Moon. A comparison about the accuracy in retrieving the lander's state with respect to the use of a probe located in the Lagrangian point L2 of the Earth-Moon system has also been carried out.

The habitable zone and extreme planetary orbits.

Science.gov (United States)

Kane, Stephen R; Gelino, Dawn M

2012-10-01

The habitable zone for a given star describes the range of circumstellar distances from the star within which a planet could have liquid water on its surface, which depends upon the stellar properties. Here we describe the development of the habitable zone concept, its application to our own solar system, and its subsequent application to exoplanetary systems. We further apply this to planets in extreme eccentric orbits and show how they may still retain life-bearing properties depending upon the percentage of the total orbit which is spent within the habitable zone. Key Words: Extrasolar planets-Habitable zone-Astrobiology.

Stable low-altitude orbits around Ganymede considering a disturbing body in a circular orbit

Science.gov (United States)

Cardoso dos Santos, J.; Carvalho, J. P. S.; Vilhena de Moraes, R.

2014-10-01

Some missions are being planned to visit Ganymede like the Europa Jupiter System Mission that is a cooperation between NASA and ESA to insert the spacecraft JGO (Jupiter Ganymede Orbiter) into Ganymedes orbit. This comprehension of the dynamics of these orbits around this planetary satellite is essential for the success of this type of mission. Thus, this work aims to perform a search for low-altitude orbits around Ganymede. An emphasis is given in polar orbits and it can be useful in the planning of space missions to be conducted around, with respect to the stability of orbits of artificial satellites. The study considers orbits of artificial satellites around Ganymede under the influence of the third-body (Jupiter's gravitational attraction) and the polygenic perturbations like those due to non-uniform distribution of mass (J_2 and J_3) of the main body. A simplified dynamic model for these perturbations is used. The Lagrange planetary equations are used to describe the orbital motion of the artificial satellite. The equations of motion are developed in closed form to avoid expansions in eccentricity and inclination. The results show the argument of pericenter circulating. However, low-altitude (100 and 150 km) polar orbits are stable. Another orbital elements behaved variating with small amplitudes. Thus, such orbits are convenient to be applied to future space missions to Ganymede. Acknowledgments: FAPESP (processes n° 2011/05671-5, 2012/12539-9 and 2012/21023-6).

Orbital misalignment of the Neptune-mass exoplanet GJ 436b with the spin of its cool star

Science.gov (United States)

Bourrier, Vincent; Lovis, Christophe; Beust, Hervé; Ehrenreich, David; Henry, Gregory W.; Astudillo-Defru, Nicola; Allart, Romain; Bonfils, Xavier; Ségransan, Damien; Delfosse, Xavier; Cegla, Heather M.; Wyttenbach, Aurélien; Heng, Kevin; Lavie, Baptiste; Pepe, Francesco

2018-01-01

The angle between the spin of a star and the orbital planes of its planets traces the history of the planetary system. Exoplanets orbiting close to cool stars are expected to be on circular, aligned orbits because of strong tidal interactions with the stellar convective envelope. Spin–orbit alignment can be measured when the planet transits its star, but such ground-based spectroscopic measurements are challenging for cool, slowly rotating stars. Here we report the three-dimensional characterization of the trajectory of an exoplanet around an M dwarf star, derived by mapping the spectrum of the stellar photosphere along the chord transited by the planet. We find that the eccentric orbit of the Neptune-mass exoplanet GJ 436b is nearly perpendicular to the stellar equator. Both eccentricity and misalignment, surprising around a cool star, can result from dynamical interactions (via Kozai migration) with a yet-undetected outer companion. This inward migration of GJ 436b could have triggered the atmospheric escape that now sustains its giant exosphere.

Eccentric figure-eight coils for transcranial magnetic stimulation.

Science.gov (United States)

Sekino, Masaki; Ohsaki, Hiroyuki; Takiyama, Yoshihiro; Yamamoto, Keita; Matsuzaki, Taiga; Yasumuro, Yoshihiro; Nishikawa, Atsushi; Maruo, Tomoyuki; Hosomi, Koichi; Saitoh, Youichi

2015-01-01

Previously we proposed an eccentric figure-eight coil that can cause threshold stimulation in the brain at lower driving currents. In this study, we performed numerical simulations and magnetic stimulations to healthy subjects for evaluating the advantages of the eccentric coil. The simulations were performed using a simplified spherical brain model and a realistic human brain model. We found that the eccentric coil required a driving current intensity of approximately 18% less than that required by the concentric coil to cause comparable eddy current densities within the brain. The eddy current localization of the eccentric coil was slightly higher than that of the concentric coil. A prototype eccentric coil was designed and fabricated. Instead of winding a wire around a bobbin, we cut eccentric-spiral slits on the insulator cases, and a wire was woven through the slits. The coils were used to deliver magnetic stimulation to healthy subjects; among our results, we found that the current slew rate corresponding to motor threshold values for the concentric and eccentric coils were 86 and 78 A/µs, respectively. The results indicate that the eccentric coil consistently requires a lower driving current to reach the motor threshold than the concentric coil. Future development of compact magnetic stimulators will enable the treatment of some intractable neurological diseases at home. © 2014 Wiley Periodicals, Inc.

Dynamique des orbites fortement elliptiques

OpenAIRE

Lion , Guillaume

2013-01-01

Most of the orbits of artificial satellites around the Earth have relatively low eccentricities. The calculation of their trajectories is very well under control, either by means of numerical methods when it comes to focus on accuracy and comparing observations, or either through analytical or semi-analytical theories to optimize the speed of calculations. This second category is used, in particular, for computing many long-term trajectories that could help to ensure the security and safety o...

Modeling electric bicycle's lane-changing and retrograde behaviors

Science.gov (United States)

Tang, Tie-Qiao; Luo, Xiao-Feng; Zhang, Jian; Chen, Liang

2018-01-01

Recently, electric bicycle (EB) has been one important traffic tool due to its own merits. However, EB's motion behaviors (especially at a signalized/non-signalized intersection) are more complex than those of vehicle since it always has lane-changing and retrograde behaviors. In this paper, we propose a model to explore EB's lane-changing and retrograde behaviors on a road with a signalized intersection. The numerical results indicate that the proposed model can qualitatively describe each EB's lane-changing and retrograde behaviors near a signalized intersection, and that lane-changing and retrograde behaviors have prominent impacts on the signalized intersection (i.e., prominent jams and congestions occur). The above results show that EB should be controlled as a vehicle, i.e., lane-changing and retrograde behaviors at a signalized intersection should strictly be prohibited to improve the operational efficiency and traffic safety at the signalized intersection.

Black Hole Mergers in Galactic Nuclei Induced by the Eccentric Kozai–Lidov Effect

Science.gov (United States)

Hoang, Bao-Minh; Naoz, Smadar; Kocsis, Bence; Rasio, Frederic A.; Dosopoulou, Fani

2018-04-01

Nuclear star clusters around a central massive black hole (MBH) are expected to be abundant in stellar black hole (BH) remnants and BH–BH binaries. These binaries form a hierarchical triple system with the central MBH, and gravitational perturbations from the MBH can cause high-eccentricity excitation in the BH–BH binary orbit. During this process, the eccentricity may approach unity, and the pericenter distance may become sufficiently small so that gravitational-wave emission drives the BH–BH binary to merge. In this work, we construct a simple proof-of-concept model for this process, and specifically, we study the eccentric Kozai–Lidov mechanism in unequal-mass, soft BH–BH binaries. Our model is based on a set of Monte Carlo simulations for BH–BH binaries in galactic nuclei, taking into account quadrupole- and octupole-level secular perturbations, general relativistic precession, and gravitational-wave emission. For a typical steady-state number of BH–BH binaries, our model predicts a total merger rate of ∼1–3 {Gpc} ‑3 {yr} ‑1, depending on the assumed density profile in the nucleus. Thus, our mechanism could potentially compete with other dynamical formation processes for merging BH–BH binaries, such as the interactions of stellar BHs in globular clusters or in nuclear star clusters without an MBH.

Flow Mode Magnetorheological Dampers with an Eccentric Gap

OpenAIRE

Young-Tai Choi; Norman M. Wereley

2014-01-01

This paper analyzes flow mode magnetorheological (MR) dampers with an eccentric annular gap (i.e., a nonuniform annular gap). To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and dam...

Conditions of Passage and Entrapment of Terrestrial Planets in Spin-Orbit Resonances

Science.gov (United States)

2012-06-10

May 25 ABSTRACT The dynamical evolution of terrestrial planets resembling Mercury in the vicinity of spin-orbit resonances is investigated using... planet and assuming a zero obliquity. We find that a Mercury -like planet with a current value of orbital eccentricity (0.2056) is always captured in... Mercury rarely fails to align itself into this state of unstable equilibrium before it traverses 2:1 resonance. Key words: celestial mechanics – planets

MULTIPLE-PLANET SCATTERING AND THE ORIGIN OF HOT JUPITERS

International Nuclear Information System (INIS)

Beaugé, C.; Nesvorný, D.

2012-01-01

Doppler and transit observations of exoplanets show a pile-up of Jupiter-size planets in orbits with a 3 day period. A fraction of these hot Jupiters have retrograde orbits with respect to the parent star's rotation, as evidenced by the measurements of the Rossiter-McLaughlin effect. To explain these observations we performed a series of numerical integrations of planet scattering followed by the tidal circularization and migration of planets that evolved into highly eccentric orbits. We considered planetary systems having three and four planets initially placed in successive mean-motion resonances, although the angles were taken randomly to ensure orbital instability in short timescales. The simulations included the tidal and relativistic effects, and precession due to stellar oblateness. Our results show the formation of two distinct populations of hot Jupiters. The inner population (Population I) is characterized by semimajor axis a 1 Gyr and fits nicely the observed 3 day pile-up. A comparison between our three-planet and four-planet runs shows that the formation of hot Jupiters is more likely in systems with more initial planets. Due to the large-scale chaoticity that dominates the evolution, high eccentricities and/or high inclinations are generated mainly by close encounters between the planets and not by secular perturbations (Kozai or otherwise). The relative proportion of retrograde planets seems of be dependent on the stellar age. Both the distribution of almost aligned systems and the simulated 3 day pile-up also fit observations better in our four-planet simulations. This may suggest that the planetary systems with observed hot Jupiters were originally rich in the number of planets, some of which were ejected. In a broad perspective, our work therefore hints on an unexpected link between the hot Jupiters and recently discovered free floating planets.

Maintaining Aura's Orbit Requirements While Performing Orbit Maintenance Maneuvers Containing an Orbit Normal Delta-V Component

Science.gov (United States)

Johnson, Megan R.; Petersen, Jeremy D.

2014-01-01

The Earth Observing System (EOS) Afternoon Constellation consists of five member missions (GCOM-W1, Aqua, CALIPSO, CloudSat, and Aura), each of which maintain a frozen, sun-synchronous orbit with a 16-day repeating ground track that follows the Worldwide Reference System-2 (WRS-2). Under nominal science operations for Aura, the propulsion system is oriented such that the resultant thrust vector is aligned 13.493 degrees away from the velocity vector along the yaw axis. When performing orbit maintenance maneuvers, the spacecraft performs a yaw slew to align the thrust vector in the appropriate direction. A new Drag Make Up (DMU) maneuver operations scheme has been implemented for Aura alleviating the need for the 13.493 degree yaw slew. The focus of this investigation is to assess the impact that no-slew DMU maneuver operations will have on Aura's Mean Local Time (MLT) which drives the required along track separation between Aura and the constellation members, as well as Aura's frozen orbit properties, eccentricity and argument of perigee. Seven maneuver strategies were analyzed to determine the best operational approach. A mirror pole strategy, with maneuvers alternating at the North and South poles, was implemented operationally to minimize impact to the MLT. Additional analysis determined that the mirror pole strategy could be further modified to include frozen orbit maneuvers and thus maintain both MLT and the frozen orbit properties under noslew operations.

Doppler-guided retrograde catheterization system

Science.gov (United States)

Frazin, Leon J.; Vonesh, Michael J.; Chandran, Krishnan B.; Khasho, Fouad; Lanza, George M.; Talano, James V.; McPherson, David D.

1991-05-01

The purpose of this study was to investigate a Doppler guided catheterization system as an adjunctive or alternative methodology to overcome the disadvantages of left heart catheterization and angiography. These disadvantages include the biological effects of radiation and the toxic and volume effects of iodine contrast. Doppler retrograde guidance uses a 20 MHz circular pulsed Doppler crystal incorporated into the tip of a triple lumen multipurpose catheter and is advanced retrogradely using the directional flow information provided by the Doppler waveform. The velocity detection limits are either 1 m/second or 4 m/second depending upon the instrumentation. In a physiologic flow model of the human aortic arch, multiple data points revealed a positive wave form when flow was traveling toward the catheter tip indicating proper alignment for retrograde advancement. There was a negative wave form when flow was traveling away from the catheter tip if the catheter was in a branch or bent upon itself indicating improper catheter tip position for retrograde advancement. In a series of six dogs, the catheter was able to be accurately advanced from the femoral artery to the left ventricular chamber under Doppler signal guidance without the use of x-ray. The potential applications of a Doppler guided retrograde catheterization system include decreasing time requirements and allowing safer catheter guidance in patients with atherosclerotic vascular disease and suspected aortic dissection. The Doppler system may allow left ventricular pressure monitoring in the intensive care unit without the need for x-ray and it may allow left sided contrast echocardiography. With pulse velocity detection limits of 4 m/second, this system may allow catheter direction and passage into the aortic root and left ventricle in patients with aortic stenosis. A modification of the Doppler catheter may include transponder technology which would allow precise catheter tip localization once the

Flow Mode Magnetorheological Dampers with an Eccentric Gap

Directory of Open Access Journals (Sweden)

Young-Tai Choi

2014-07-01

Full Text Available This paper analyzes flow mode magnetorheological (MR dampers with an eccentric annular gap (i.e., a nonuniform annular gap. To this end, an MR damper analysis for an eccentric annular gap is constructed based on approximating the eccentric annular gap using a rectangular duct with a variable gap, as well as a Bingham-plastic constitutive model of the MR fluid. Performance of flow mode MR dampers with an eccentric gap was assessed analytically using both field-dependent damping force and damping coefficient, which is the ratio of equivalent viscous field-on damping to field-off damping. In addition, damper capabilities of flow mode MR dampers with an eccentric gap were compared to a concentric gap (i.e., uniform annular gap.

Biomechanical characteristics of the eccentric Achilles tendon exercise

DEFF Research Database (Denmark)

Henriksen, Marius; Aaboe, Jens; Bliddal, Henning

2009-01-01

that although the tendon loads are similar, the tendon is vibrated at higher frequencies during the eccentric phase than during the concentric phases. This study provides data that may explain the mechanisms behind the effectiveness of eccentric exercises used in the treatment of Achilles tendinopathies........ No differences in Achilles tendon loads were found. INTERPRETATION: This descriptive study demonstrates differences in the movement biomechanics between the eccentric and concentric phases of one-legged full weight bearing ankle dorsal and plantar flexion exercises. In particular, the findings imply......BACKGROUND: Eccentric exercise has been shown to provide good short-term clinical results in the treatment of painful mid-portion chronic Achilles tendinopathies. However, the mechanisms behind the positive effects of eccentric rehabilitation regimes are not known, and research...

Retrograde amnesia in patients with Alzheimer's disease

NARCIS (Netherlands)

Meeter, M.; Eijsackers, E; Mulder, J

2006-01-01

Patients with mild to moderate Alzheimer's disease and normal controls were tested on two retrograde memory tests, one based on public events, and the other querying autobiographical memory. On both tests, patients showed strong decrements as compared to normal controls, pointing to retrograde

EXTRACTING PLANET MASS AND ECCENTRICITY FROM TTV DATA

International Nuclear Information System (INIS)

Lithwick, Yoram; Xie Jiwei; Wu Yanqin

2012-01-01

Most planet pairs in the Kepler data that have measured transit time variations (TTVs) are near first-order mean-motion resonances. We derive analytical formulae for their TTV signals. We separate planet eccentricity into free and forced parts, where the forced part is purely due to the planets' proximity to resonance. This separation yields simple analytical formulae. The phase of the TTV depends sensitively on the presence of free eccentricity: if the free eccentricity vanishes, the TTV will be in phase with the longitude of conjunctions. This effect is easily detectable in current TTV data. The amplitude of the TTV depends on planet mass and free eccentricity, and it determines planet mass uniquely only when the free eccentricity is sufficiently small. We analyze the TTV signals of six short-period Kepler pairs. We find that three of these pairs (Kepler 18, 24, 25) have a TTV phase consistent with zero. The other three (Kepler 23, 28, 32) have small TTV phases, but ones that are distinctly non-zero. We deduce that the free eccentricities of the planets are small, ∼< 0.01, but not always vanishing. Furthermore, as a consequence of this, we deduce that the true masses of the planets are fairly accurately determined by the TTV amplitudes, within a factor of ∼< 2. The smallness of the free eccentricities suggests that the planets have experienced substantial dissipation. This is consistent with the hypothesis that the observed pile-up of Kepler pairs near mean-motion resonances is caused by resonant repulsion. But the fact that some of the planets have non-vanishing free eccentricity suggests that after resonant repulsion occurred there was a subsequent phase in the planets' evolution when their eccentricities were modestly excited, perhaps by interplanetary interactions.

The Orbit of X Persei and Its Neutron Star Companion

Science.gov (United States)

Delgado-Martí, Hugo; Levine, Alan M.; Pfahl, Eric; Rappaport, Saul A.

2001-01-01

We have observed the Be/X-ray pulsar binary system X Per/4U 0352+30 on 61 occasions spanning an interval of 600 days with the PCA instrument on board the Rossi X-Ray Timing Explorer (RXTE). Pulse timing analyses of the 837 s pulsations yield strong evidence for the presence of orbital Doppler delays. We confirm the Doppler delays by using measurements made with the All Sky Monitor (ASM) on RXTE. We infer that the orbit is characterized by a period Porb=250 days, a projected semimajor axis of the neutron star axsini=454 lt-s, a mass function f(M)=1.61 Msolar, and a modest eccentricity e=0.11. The measured orbital parameters, together with the known properties of the classical Be star X Per, imply a semimajor axis a=1.8-2.2 AU and an orbital inclination i~26deg-33deg. We discuss the formation of the system in the context of the standard evolutionary scenario for Be/X-ray binaries. We find that the system most likely formed from a pair of massive progenitor stars and probably involved a quasi-stable and nearly conservative transfer of mass from the primary to the secondary. We find that the He star remnant of the primary most likely had a mass probability of a system like that of X Per forming with an orbital eccentricity e<~0.11. We speculate that there may be a substantial population of neutron stars formed with little or no kick. Finally, we discuss the connected topics of the wide orbit and accretion by the neutron star from a stellar wind.

Resonant Orbital Dynamics in LEO Region: Space Debris in Focus

Directory of Open Access Journals (Sweden)

J. C. Sampaio

2014-01-01

Full Text Available The increasing number of objects orbiting the earth justifies the great attention and interest in the observation, spacecraft protection, and collision avoidance. These studies involve different disturbances and resonances in the orbital motions of these objects distributed by the distinct altitudes. In this work, objects in resonant orbital motions are studied in low earth orbits. Using the two-line elements (TLE of the NORAD, resonant angles and resonant periods associated with real motions are described, providing more accurate information to develop an analytical model that describes a certain resonance. The time behaviors of the semimajor axis, eccentricity, and inclination of some space debris are studied. Possible irregular motions are observed by the frequency analysis and by the presence of different resonant angles describing the orbital dynamics of these objects.

Quasi-eccentricity error modeling and compensation in vision metrology

Science.gov (United States)

Shen, Yijun; Zhang, Xu; Cheng, Wei; Zhu, Limin

2018-04-01

Circular targets are commonly used in vision applications for its detection accuracy and robustness. The eccentricity error of the circular target caused by perspective projection is one of the main factors of measurement error which needs to be compensated in high-accuracy measurement. In this study, the impact of the lens distortion on the eccentricity error is comprehensively investigated. The traditional eccentricity error turns to a quasi-eccentricity error in the non-linear camera model. The quasi-eccentricity error model is established by comparing the quasi-center of the distorted ellipse with the true projection of the object circle center. Then, an eccentricity error compensation framework is proposed which compensates the error by iteratively refining the image point to the true projection of the circle center. Both simulation and real experiment confirm the effectiveness of the proposed method in several vision applications.

Retrograde amnesia for semantic information in Alzheimer's disease

OpenAIRE

Meeter, M.; Kollen, A.; Scheltens, P.

2005-01-01

Patients with mild to moderate Alzheimer's disease and normal controls were tested on a retrograde amnesia test with semantic content (Neologism and Vocabulary Test, or NVT), consisting of neologisms to be defined. Patients showed a decrement as compared to normal controls, pointing to retrograde amnesia within semantic memory. No evidence for a gradient within this amnesia was found, although one was present on an autobiographic test of retrograde amnesia that had a wider time scale. Several...

A Free-Return Earth-Moon Cycler Orbit for an Interplanetary Cruise Ship

Science.gov (United States)

Genova, Anthony L.; Aldrin, Buzz

2015-01-01

A periodic circumlunar orbit is presented that can be used by an interplanetary cruise ship for regular travel between Earth and the Moon. This Earth-Moon cycler orbit was revealed by introducing solar gravity and modest phasing maneuvers (average of 39 m/s per month) which yields close-Earth encounters every 7 or 10 days. Lunar encounters occur every 26 days and offer the chance for a smaller craft to depart the cycler and enter lunar orbit, or head for a Lagrange point (e.g., EM-L2 halo orbit), distant retrograde orbit (DRO), or interplanetary destination such as a near-Earth object (NEO) or Mars. Additionally, return-to-Earth abort options are available from many points along the cycling trajectory.

Long-Term Prediction of Satellite Orbit Using Analytical Method

Directory of Open Access Journals (Sweden)

Jae-Cheol Yoon

1997-12-01

Full Text Available A long-term prediction algorithm of geostationary orbit was developed using the analytical method. The perturbation force models include geopotential upto fifth order and degree and luni-solar gravitation, and solar radiation pressure. All of the perturbation effects were analyzed by secular variations, short-period variations, and long-period variations for equinoctial elements such as the semi-major axis, eccentricity vector, inclination vector, and mean longitude of the satellite. Result of the analytical orbit propagator was compared with that of the cowell orbit propagator for the KOREASAT. The comparison indicated that the analytical solution could predict the semi-major axis with an accuarcy of better than ~35meters over a period of 3 month.

Retrograde prostatic urethroplasty with balloon catheter

International Nuclear Information System (INIS)

Castaneda, F.; Reddy, P.; Hulbert, J.; Letourneau, J.G.; Hunter, D.W.; Castaneda-Zuniga, W.R.; Amplatz, K.

1987-01-01

The authors performed retrograde prostatic urethroplasty in 18 patients using a 25-mm urethroplasty balloon catheter. The procedure was performed on an outpatient basis under local anesthesia. Voiding cystourethrography, retrograde urethrography, rectal US, and MRE imaging were performed before and immediately after the procedure and at 2 weeks and 3, 6, 12, and 18 months. Long-term results at 18 months and possible clinical implications are discussed

Human rather than ape-like orbital morphology allows much greater lateral visual field expansion with eye abduction

Science.gov (United States)

Denion, Eric; Hitier, Martin; Levieil, Eric; Mouriaux, Frédéric

2015-01-01

While convergent, the human orbit differs from that of non-human apes in that its lateral orbital margin is significantly more rearward. This rearward position does not obstruct the additional visual field gained through eye motion. This additional visual field is therefore considered to be wider in humans than in non-human apes. A mathematical model was designed to quantify this difference. The mathematical model is based on published computed tomography data in the human neuro-ocular plane (NOP) and on additional anatomical data from 100 human skulls and 120 non-human ape skulls (30 gibbons; 30 chimpanzees / bonobos; 30 orangutans; 30 gorillas). It is used to calculate temporal visual field eccentricity values in the NOP first in the primary position of gaze then for any eyeball rotation value in abduction up to 45° and any lateral orbital margin position between 85° and 115° relative to the sagittal plane. By varying the lateral orbital margin position, the human orbit can be made “non-human ape-like”. In the Pan-like orbit, the orbital margin position (98.7°) was closest to the human orbit (107.1°). This modest 8.4° difference resulted in a large 21.1° difference in maximum lateral visual field eccentricity with eyeball abduction (Pan-like: 115°; human: 136.1°). PMID:26190625

Moderate Load Eccentric Exercise; A Distinct Novel Training Modality

Science.gov (United States)

Hoppeler, Hans

2016-01-01

Over the last 20 years a number of studies have been published using progressive eccentric exercise protocols on motorized ergometers or similar devices that allow for controlled application of eccentric loads. Exercise protocols ramp eccentric loads over an initial 3 weeks period in order to prevent muscle damage and delayed onset muscle soreness. Final training loads reach 400–500 W in rehabilitative settings and over 1200 W in elite athletes. Training is typically carried out three times per week for durations of 20–30 min. This type of training has been characterizes as moderate load eccentric exercise. It has also been denoted RENEW (Resistance Exercise via Negative Eccentric Work by LaStayo et al., 2014). It is distinct from plyometric exercises (i.e., drop jumps) that impose muscle loads of several thousand Watts on muscles and tendons. It is also distinct from eccentric overload training whereby loads in a conventional strength training setting are increased in the eccentric phase of the movement to match concentric loads. Moderate load eccentric exercise (or RENEW) has been shown to be similarly effective as conventional strength training in increasing muscle strength and muscle volume. However, as carried out at higher angular velocities of joint movement, it reduces joint loads. A hallmark of moderate load eccentric exercise is the fact that the energy requirements are typically 4-fold smaller than in concentric exercise of the same load. This makes moderate load eccentric exercise training the tool of choice in medical conditions with limitations in muscle energy supply. The use and effectiveness of moderate load eccentric exercise has been demonstrated mostly in small scale studies for cardiorespiratory conditions, sarcopenia of old age, cancer, diabetes type 2, and neurological conditions. It has also been used effectively in the prevention and rehabilitation of injuries of the locomotor system in particular the rehabilitation after anterior

Retrograde transurethral balloon dilation of the prostate

International Nuclear Information System (INIS)

Castaneda, F.; Reddy, P.; Wasserman, N.F.; Lund, G.; Hulbert, J.; Hunter, D.; Castaneda-Zuniga, W.R.; Amplatz, K.

1986-01-01

A series of patients with documented benign prostatic hypertrophy evaluated by urodynamic studies, voiding cystourethrography, retrograde urethrography, and MR imaging underwent dilation performed using a retrograde transurethral approach with 25-mm balloon dilators inflated at a pressure of 3-4 atm for 10 minutes. Immediately after the procedure, retrograde and voiding cystourethrography as well as MR imaging were performed. A Foley catheter was left in place for 24 hours. Complete relief of symptoms has occurred in all of the patients during the follow-up period. No significant complications other than transient hematuria resulted from the procedure. Results of the comparison studies and of MR imaging are discussed

Retrograde Renal Cooling to Minimize Ischemia

Directory of Open Access Journals (Sweden)

Janet L. Colli

2013-01-01

Full Text Available Objective: During partial nephrectomy, renal hypothermia has been shown to decrease ischemia induced renal damage which occurs from renal hilar clamping. In this study we investigate the infusion rate required to safely cool the entire renal unit in a porcine model using retrograde irrigation of iced saline via dual-lumen ureteral catheter. Materials and Methods: Renal cortical, renal medullary, bowel and rectal temperatures during retrograde cooling in a laparoscopic porcine model were monitored in six renal units. Iced normal saline was infused at 300 cc/hour, 600 cc/hour, 1000 cc/hour and gravity (800 cc/hour for 600 seconds with and without hilar clamping. Results: Retrograde cooling with hilar clamping provided rapid medullary renal cooling and significant hypothermia of the medulla and cortex at infusion rates ≥ 600 cc/hour. With hilar clamping, cortical temperatures decreased at -0.9° C/min. reaching a threshold temperature of 26.9° C, and medullary temperatures decreased at -0.90 C/min. reaching a temperature of 26.1° C over 600 seconds on average for combined data at infusion rates ≥ 600 cc/hour. The lowest renal temperatures were achieved with gravity infusion. Without renal hilum clamping, retrograde cooling was minimal at all infusion rates. Conclusions: Significant renal cooling by gravity infusion of iced cold saline via a duel lumen catheter with a clamped renal hilum was achieved in a porcine model. Continuous retrograde irrigation with iced saline via a two way ureteral catheter may be an effective method to induce renal hypothermia in patients undergoing robotic assisted and/or laparoscopic partial nephrectomy.

A Dynamical Systems Approach to the Design of the Science Orbit Around Europa

Science.gov (United States)

Gomez, Gerard; Lara, Martin; Russell, Ryan P.

2006-01-01

The science orbit for a future mission to Europa requires low eccentricity, low altitude, and high inclination. However, high inclination orbits around planetary satellites are unstable due to third-body perturbations. Without control, the orbiter impacts Europa after few weeks. To minimize control, a tour over the stable-unstable, averaged manifolds of unstable frozen orbits has been suggested. We proceed with the unaveraged equations and study the manifolds of unstable orbits that are periodic in a rotating frame attached to Europa. Massive numerical computation helps in understanding the unstable dynamics close to Europa, and, thus, in selecting long lifetime high inclination orbits. A final test of a selected set of initial conditions on a high fidelity, ephemeris model, validate the results.

The Early Lunar Orbit and Principal Moments of Inertia

Science.gov (United States)

Garrick-Bethell, I.; Zuber, M. T.

2007-12-01

If taken at face value, the principal lunar moments of inertia suggest that the Moon froze in a past tidal and rotational state during a high eccentricity orbit [1]. At this time the Moon may have been in either synchronous rotation or in a 3:2 resonance of spin and mean motion. We have performed further investigations of the plausibility of past high eccentricity lunar orbits on the basis of orbital evolution, the dynamics of entry into any past 3:2 resonance, and tidal dissipation. We have found that the requisite permanent (B-A)/C (where A, B, and C are the principal moments of inertia) for a 3:2 resonance can be achieved in a magma ocean if a density anomaly is present shortly after lunar accretion. In a high eccentricity orbit, tidal dissipation will affect the Moon's ability to develop lithospheric strength. The Moon is presently able to support degree-two loads, while Io, which is approximately the same size as the Moon and strongly heated by tidal dissipation, probably cannot [2]. Therefore, somewhere between the present lunar radioactive heating rate (~1012 W), and Io's observed dissipation (~1014 W), the Moon may develop lithospheric strength. We use 1014 W as a loose upper bound on where freeze-in may begin and find that in a 3:2 resonance tidal dissipation [3] can drop below 1014 W at a = 25 RE and e = 0.17, and the present moments of inertia can be approximately reproduced for lunar values of QM = 475 (where a is the lunar semimajor axis, RE is the Earth radius, and Q is the specific dissipation function). This value of QM is somewhat large, but the biggest problem with a 3:2 resonance that lasts until 25 RE is how to achieve the current low eccentricity synchronous orbit. The required damping cannot be easily achieved unless the Moon is knocked out of a 3:2 resonance by an impactor that would produce a crater approximately 800 km in diameter. In sum, there is no single strong constraint that completely rules out a 3:2 resonance, but it would require a

The inherent catastrophic traps in retrograde CTO PCI.

Science.gov (United States)

Wu, Eugene B; Tsuchikane, Etsuo

2018-05-01

When we learn to drive, our driving instructor tells us how to check the side mirror and turn your head to check the blind spot before changing lanes. He tells us how to stop at stop signs, how to drive in slippery conditions, the safe stopping distances, and these all make our driving safe. Similarly, when we learn PCI, our mentors teach us to seat the guiding catheter co-axially, to wire the vessel safely, to deliver balloon and stents over the wire, to watch the pressure of the guiding, in order that we perform PCI safely and evade complications. In retrograde CTO PCI, there is no such published teaching. Also many individual mentors have not had the wide experience to see all the possible complications of retrograde CTO PCI and, therefore, may not be able to warn their apprentice. As the number of retrograde procedures increase worldwide, there is a corresponding increase in catastrophic complications, many of which, we as experts, can see are easily avoidable. To breach this gap in knowledge, this article describes 12 commonly met inherent traps in retrograde CTO PCI. They are inherent because by arranging our equipment in the manner to perform retrograde CTO PCI, these complications are either induced directly or happen easily. We hope this work will enhance safety of retrograde CTO PCI and avoid many catastrophic complications for our readers and operators. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

Criteria for retrograde rotation of accreting black holes

Science.gov (United States)

Mikhailov, A. G.; Piotrovich, M. Yu; Gnedin, Yu N.; Natsvlishvili, T. M.; Buliga, S. D.

2018-06-01

Rotating supermassive black holes produce jets and their origin is connected to the magnetic field that is generated by accreting matter flow. There is a point of view that electromagnetic fields around rotating black holes are brought to the hole by accretion. In this situation the prograde accreting discs produce weaker large-scale black hole threading magnetic fields, implying weaker jets than in retrograde regimes. The basic goal of this paper is to find the best candidates for retrograde accreting systems in observed active galactic nuclei. We show that active galactic nuclei with low Eddington ratio are really the best candidates for retrograde systems. This conclusion is obtained for kinetically dominated Fanaroff-Riley class II radio galaxies, flat-spectrum radio-loud narrow-line Seyfert I galaxies and a number of nearby galaxies. Our conclusion is that the best candidates for retrograde systems are the noticeable population of active galactic nuclei in the Universe. This result corresponds to the conclusion that in the merging process the interaction of merging black holes with a retrograde circumbinary disc is considerably more effective for shrinking the binary system.

Grinding Method and Error Analysis of Eccentric Shaft Parts

Science.gov (United States)

Wang, Zhiming; Han, Qiushi; Li, Qiguang; Peng, Baoying; Li, Weihua

2017-12-01

RV reducer and various mechanical transmission parts are widely used in eccentric shaft parts, The demand of precision grinding technology for eccentric shaft parts now, In this paper, the model of X-C linkage relation of eccentric shaft grinding is studied; By inversion method, the contour curve of the wheel envelope is deduced, and the distance from the center of eccentric circle is constant. The simulation software of eccentric shaft grinding is developed, the correctness of the model is proved, the influence of the X-axis feed error, the C-axis feed error and the wheel radius error on the grinding process is analyzed, and the corresponding error calculation model is proposed. The simulation analysis is carried out to provide the basis for the contour error compensation.

Retrograde amnesia after electroconvulsive therapy: a temporary effect?

NARCIS (Netherlands)

Meeter, M.; Murre, J.M.J.; Janssen, S.M.J.; Birkenhager, T.; van den Broek, W.W.

2011-01-01

Objective: Although electroconvulsive therapy (ECT) is generally considered effective against depression, it remains controversial because of its association with retrograde memory loss. Here, we assessed memory after ECT in circumstances most likely to yield strong retrograde amnesia. Method: A

Ultrasonic guided waves in eccentric annular pipes

International Nuclear Information System (INIS)

Pattanayak, Roson Kumar; Balasubramaniam, Krishnan; Rajagopal, Prabhu

2014-01-01

This paper studies the feasibility of using ultrasonic guided waves to rapidly inspect tubes and pipes for possible eccentricity. While guided waves are well established in the long range inspection of structures such as pipes and plates, studies for more complex cross sections are limited and analytical solutions are often difficult to obtain. Recent developments have made the Semi Analytical Finite Element (SAFE) method widely accessible for researchers to study guided wave properties in complex structures. Here the SAFE method is used to study the effect of eccentricity on the modal structures and velocities of lower order guided wave modes in thin pipes of diameters typically of interest to the industry. Results are validated using experiments. The paper demonstrates that even a small eccentricity in the pipe can strongly affect guided wave mode structures and velocities and hence shows potential for pipe eccentricity inspection

Electromyographic analysis of repeated bouts of eccentric exercise.

Science.gov (United States)

McHugh, M P; Connolly, D A; Eston, R G; Gartman, E J; Gleim, G W

2001-03-01

The repeated bout effect refers to the protective effect provided by a single bout of eccentric exercise against muscle damage from a similar subsequent bout. The aim of this study was to determine if the repeated bout was associated with an increase in motor unit activation relative to force production, an increased recruitment of slow-twitch motor units or increased motor unit synchronization. Surface electromyographic (EMG) signals were recorded from the hamstring muscles during two bouts of submaximal isokinetic (2.6 rad x s(-1)) eccentric (11 men, 9 women) or concentric (6 men, 4 women) contractions separated by 2 weeks. The EMG per unit torque and median frequency were analysed. The initial bout of eccentric exercise resulted in strength loss, pain and muscle tenderness, while the repeated eccentric bout resulted in a slight increase in strength, no pain and no muscle tenderness (bout x time effects, P exercise. The EMG per unit torque and median frequency were not different between the initial and repeated bouts of eccentric exercise. The EMG per unit torque and median frequency increased during both bouts of eccentric exercise (P < 0.01) but did not change during either concentric bout. In conclusion, there was no evidence that the repeated bout effect was due to a neural adaptation.

OPEX: Optimized Eccentricity Computation in Graphs

Energy Technology Data Exchange (ETDEWEB)

Henderson, Keith [Lawrence Livermore National Lab. (LLNL), Livermore, CA (United States)

2011-11-14

Real-world graphs have many properties of interest, but often these properties are expensive to compute. We focus on eccentricity, radius and diameter in this work. These properties are useful measures of the global connectivity patterns in a graph. Unfortunately, computing eccentricity for all nodes is O(n2) for a graph with n nodes. We present OPEX, a novel combination of optimizations which improves computation time of these properties by orders of magnitude in real-world experiments on graphs of many different sizes. We run OPEX on graphs with up to millions of links. OPEX gives either exact results or bounded approximations, unlike its competitors which give probabilistic approximations or sacrifice node-level information (eccentricity) to compute graphlevel information (diameter).

THE NASA-UC ETA-EARTH PROGRAM. III. A SUPER-EARTH ORBITING HD 97658 AND A NEPTUNE-MASS PLANET ORBITING Gl 785

International Nuclear Information System (INIS)

Howard, Andrew W.; Marcy, Geoffrey W.; Isaacson, Howard; Johnson, John Asher; Fischer, Debra A.; Wright, Jason T.; Henry, Gregory W.; Valenti, Jeff A.; Anderson, Jay; Piskunov, Nikolai E.

2011-01-01

We report the discovery of planets orbiting two bright, nearby early K dwarf stars, HD 97658 and Gl 785. These planets were detected by Keplerian modeling of radial velocities measured with Keck-HIRES for the NASA-UC Eta-Earth Survey. HD 97658 b is a close-in super-Earth with minimum mass Msin i = 8.2 ± 1.2 M + , orbital period P = 9.494 ± 0.005 days, and an orbit that is consistent with circular. Gl 785 b is a Neptune-mass planet with Msin i = 21.6 ± 2.0 M + , P = 74.39 ± 0.12 days, and orbital eccentricity e = 0.30 ± 0.09. Photometric observations with the T12 0.8 m automatic photometric telescope at Fairborn Observatory show that HD 97658 is photometrically constant at the radial velocity period to 0.09 mmag, supporting the existence of the planet.

Dynamic eccentricity fault diagnosis in round rotor synchronous motors

International Nuclear Information System (INIS)

Ebrahimi, Bashir Mahdi; Etemadrezaei, Mohammad; Faiz, Jawad

2011-01-01

Research highlights: → We have presented a novel approach to detect dynamic eccentricity in round rotor synchronous motors. → We have introduced an efficient index based on processing torque using time series data mining method. → The stator current spectrum of the motor under different levels of fault and load are computed. → Winding function method has been employed to model healthy and faulty synchronous motors. -- Abstract: In this paper, a novel approach is presented to detect dynamic eccentricity in round rotor synchronous motors. For this, an efficient index is introduced based on processing developed torque using time series data mining (TSDM) method. This index can be utilized to diagnose eccentricity fault and its degree. The capability of this index to predict dynamic eccentricity is illustrated by investigation of load variation impacts on the nominated index. Stator current spectrum of the faulty synchronous motor under different loads and dynamic eccentricity degrees are computed. Effects of the dynamic eccentricity and load variation simultaneously are scrutinized on the magnitude of 17th and 19th harmonic components as traditional indices for eccentricity fault diagnosis in synchronous motors. Necessity signals and parameters for processing and feature extraction are evaluated by winding function method which is employed to model healthy and faulty synchronous motors.

Application of Semi-analytical Satellite Theory orbit propagator to orbit determination for space object catalog maintenance

Science.gov (United States)

Setty, Srinivas J.; Cefola, Paul J.; Montenbruck, Oliver; Fiedler, Hauke

2016-05-01

Catalog maintenance for Space Situational Awareness (SSA) demands an accurate and computationally lean orbit propagation and orbit determination technique to cope with the ever increasing number of observed space objects. As an alternative to established numerical and analytical methods, we investigate the accuracy and computational load of the Draper Semi-analytical Satellite Theory (DSST). The standalone version of the DSST was enhanced with additional perturbation models to improve its recovery of short periodic motion. The accuracy of DSST is, for the first time, compared to a numerical propagator with fidelity force models for a comprehensive grid of low, medium, and high altitude orbits with varying eccentricity and different inclinations. Furthermore, the run-time of both propagators is compared as a function of propagation arc, output step size and gravity field order to assess its performance for a full range of relevant use cases. For use in orbit determination, a robust performance of DSST is demonstrated even in the case of sparse observations, which is most sensitive to mismodeled short periodic perturbations. Overall, DSST is shown to exhibit adequate accuracy at favorable computational speed for the full set of orbits that need to be considered in space surveillance. Along with the inherent benefits of a semi-analytical orbit representation, DSST provides an attractive alternative to the more common numerical orbit propagation techniques.

A CAUTIONARY TALE: MARVELS BROWN DWARF CANDIDATE REVEALS ITSELF TO BE A VERY LONG PERIOD, HIGHLY ECCENTRIC SPECTROSCOPIC STELLAR BINARY

International Nuclear Information System (INIS)

Mack, Claude E. III; Stassun, Keivan G.; De Lee, Nathan; Ge, Jian; Fleming, Scott W.; Deshpande, Rohit; Mahadevan, Suvrath; Wisniewski, John P.; Gaudi, B. Scott; Eastman, Jason; Beatty, Thomas G.; Ghezzi, Luan; González Hernández, Jonay I.; Femenía, Bruno; Mata Sánchez, Daniel; Ferreira, Letícia; Porto de Mello, Gustavo; Crepp, Justin R.; Agol, Eric; Bizyaev, Dmitry

2013-01-01

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R ∼ Jup ) to a solar-type primary. At least three properties of this system allow it to masquerade as a single star with a very-low-mass companion: its large eccentricity (e ∼ 0.8), its relatively long period (P ∼ 238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight (ω ∼ 189°). As a result of these properties, for ∼95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e ∼ 0.3). Only during the ∼5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of ∼15 km s –1 reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.

Retrograde amnesia for semantic information in Alzheimer's disease

NARCIS (Netherlands)

Meeter, M.; Kollen, A.; Scheltens, P.

2005-01-01

Patients with mild to moderate Alzheimer's disease and normal controls were tested on a retrograde amnesia test with semantic content (Neologism and Vocabulary Test, or NVT), consisting of neologisms to be defined. Patients showed a decrement as compared to normal controls, pointing to retrograde

Disrupting circadian rhythms in rats induces retrograde amnesia

NARCIS (Netherlands)

Fekete, Mátyás; Ree, J.M. van; Niesink, Raymond J.M.; Wied, D. de

1985-01-01

Disrupting circadian organization in rats by phase-shifting the illumination cycle or by exposure to a reversed day/night cycle or to continuous light, resulted in retrograde amnesia for passive avoidance behavior. This retrograde amnesia induced by phase-shifting lasted at least 2 days, and

Homoclinic orbits around spinning black holes. I. Exact solution for the Kerr separatrix

International Nuclear Information System (INIS)

Levin, Janna; Perez-Giz, Gabe

2009-01-01

For equatorial Kerr orbits, we show that each separatrix between bound and plunging geodesics is a homoclinic orbit--an orbit that asymptotes to an energetically-bound, unstable circular orbit. We derive exact expressions for these trajectories in terms of elementary functions. We also clarify the formal connection between the separatrix and zoom-whirl orbits and show that, contrary to popular belief, zoom-whirl behavior is not intrinsically a near-separatrix phenomenon. This paper focuses on homoclinic behavior in physical space, while in a companion paper we paint the complementary phase space portrait. Although they refer to geodesic motion, the exact solutions for the Kerr separatrix could be useful for analytic or numerical studies of eccentric transitions from orbital to plunging motion under the dissipative effects of gravitational radiation.

The Habitable Zone and Extreme Planetary Orbits

OpenAIRE

Kane, Stephen R.; Gelino, Dawn M.

2012-01-01

The habitable zone for a given star describes the range of circumstellar distances from the star within which a planet could have liquid water on its surface, which depends upon the stellar properties. Here we describe the development of the habitable zone concept, its application to our own solar system, and its subsequent application to exoplanetary systems. We further apply this to planets in extreme eccentric orbits and show how they may still retain life-bearing properties depending upon...

The Interior and Orbital Evolution of Charon as Preserved in Its Geologic Record

Science.gov (United States)

Rhoden, Alyssa Rose; Henning, Wade; Hurford, Terry A.; Hamilton, Douglas P.

2014-01-01

Pluto and its largest satellite, Charon, currently orbit in a mutually synchronous state; both bodies continuously show the same face to one another. This orbital configuration is a natural end-state for bodies that have undergone tidal dissipation. In order to achieve this state, both bodies would have experienced tidal heating and stress, with the extent of tidal activity controlled by the orbital evolution of Pluto and Charon and by the interior structure and rheology of each body. As the secondary, Charon would have experienced a larger tidal response than Pluto, which may have manifested as observable tectonism. Unfortunately, there are few constraints on the interiors of Pluto and Charon. In addition, the pathway by which Charon came to occupy its present orbital state is uncertain. If Charon's orbit experienced a high-eccentricity phase, as suggested by some orbital evolution models, tidal effects would have likely been more significant. Therefore, we determine the conditions under which Charon could have experienced tidally-driven geologic activity and the extent to which upcoming New Horizons spacecraft observations could be used to constrain Charon's internal structure and orbital evolution. Using plausible interior structure models that include an ocean layer, we find that tidally-driven tensile fractures would likely have formed on Charon if its eccentricity were on the order of 0.01, especially if Charon were orbiting closer to Pluto than at present. Such fractures could display a variety of azimuths near the equator and near the poles, with the range of azimuths in a given region dependent on longitude; east-west-trending fractures should dominate at mid-latitudes. The fracture patterns we predict indicate that Charon's surface geology could provide constraints on the thickness and viscosity of Charon's ice shell at the time of fracture formation.

Chain hexagonal cacti with the extremal eccentric distance sum.

Science.gov (United States)

Qu, Hui; Yu, Guihai

2014-01-01

Eccentric distance sum (EDS), which can predict biological and physical properties, is a topological index based on the eccentricity of a graph. In this paper we characterize the chain hexagonal cactus with the minimal and the maximal eccentric distance sum among all chain hexagonal cacti of length n, respectively. Moreover, we present exact formulas for EDS of two types of hexagonal cacti.

Collisional Cascades Following Triton's Capture

Science.gov (United States)

Cuk, Matija; Hamilton, Douglas P.; Stewart-Mukhopadhyay, Sarah T.

2017-10-01

Neptune's moon Triton is widely thought to have been captured from heliocentric orbit, most likely through binary dissociation (Agnor and Hamilton, 2006). Triton's original eccentric orbit must have been subsequently circularized by satellite tides (Goldreich et al. 1989). Cuk and Gladman (2005) found that Kozai oscillations make early tidal evolution inefficient, and have proposed that collisions between Triton and debris from pre-existing satellites was the dominant mechanism of shrinking Triton's large post-capture orbit. However, Cuk and Hamilton (DPS 2016), using numerical simulations and results of Stewart and Leinhardt (2012), have found that collisions between regular satellites are unlikely to be destructive, while collisions between prograde moons and Triton are certainly erosive if not catastrophic. An obvious outcome would be pre-existing moon material gradually grinding down Triton and making it reaccrete in the local Laplace plane, in conflict with Triton's large current inclination. We propose that the crucial ingredient for understanding the early evolution of the Neptunian system are the collisions between the moons and the prograde and retrograde debris originating from the pre-existing moons and Triton. In particular, we expect early erosive impact(s) on Triton to generate debris that will, in subsequent collisions, disrupt the regular satellites. If the retrograde material were to dominate at some planetocentric distances, the end result may be a large cloud or disk of retrograde debris that would be accreted by Triton, shrinking Triton's orbit. Some of the prograde debris could survive in a compact disk interior to Triton's pericenter, eventually forming the inner moons of Neptune. We will present results of numerical modeling of these complex dynamical processes at the meeting.

Achilles tendinopathy modulates force frequency characteristics of eccentric exercise.

Science.gov (United States)

Grigg, Nicole L; Wearing, Scott C; O'Toole, John M; Smeathers, James E

2013-03-01

Previous research has demonstrated that ground reaction force (GRF) recorded during eccentric ankle exercise is characterized by greater power in the 8- to 12-Hz bandwidth when compared with that recorded during concentric ankle exercise. Subsequently, it was suggested that vibrations in this bandwidth may underpin the beneficial effect of eccentric loading in tendon repair. However, this observation has been made only in individuals without Achilles tendinopathy. This research compared the force frequency characteristics of eccentric and concentric exercises in individuals with and without Achilles tendinopathy. Eleven male adults with unilateral midportion Achilles tendinopathy and nine control male adults without tendinopathy participated in the research. Kinematics and GRF were recorded while the participants performed a common eccentric rehabilitation exercise protocol and a concentric equivalent. Ankle joint kinematics and the frequency power spectrum of the resultant GRF were calculated. Eccentric exercise was characterized by a significantly greater proportion of spectral power between 4.5 and 11.5 Hz when compared with concentric exercise. There were no significant differences between limbs in the force frequency characteristics of concentric exercise. Eccentric exercise, in contrast, was defined by a shift in the power spectrum of the symptomatic limb, resulting in a second spectral peak at 9 Hz, rather than 10 Hz in the control limb. Compared with healthy tendon, Achilles tendinopathy was characterized by lower frequency vibrations during eccentric rehabilitation exercises. This finding may be associated with changes in neuromuscular activation and tendon stiffness that have been shown to occur with tendinopathy and provides a possible rationale for the previous observation of a different biochemical response to eccentric exercise in healthy and injured Achilles tendons.

Functional Outcomes of the Knee after Retrograde and Antegrade ...

African Journals Online (AJOL)

of femur shaft fractures although retrograde technique is gaining acceptance. Although ... Antegrade group, while the rate of knee stiffness was higher in the retrograde .... reaching direct and indirect social economic effect within the society.

Representation of Probability Density Functions from Orbit Determination using the Particle Filter

Science.gov (United States)

Mashiku, Alinda K.; Garrison, James; Carpenter, J. Russell

2012-01-01

Statistical orbit determination enables us to obtain estimates of the state and the statistical information of its region of uncertainty. In order to obtain an accurate representation of the probability density function (PDF) that incorporates higher order statistical information, we propose the use of nonlinear estimation methods such as the Particle Filter. The Particle Filter (PF) is capable of providing a PDF representation of the state estimates whose accuracy is dependent on the number of particles or samples used. For this method to be applicable to real case scenarios, we need a way of accurately representing the PDF in a compressed manner with little information loss. Hence we propose using the Independent Component Analysis (ICA) as a non-Gaussian dimensional reduction method that is capable of maintaining higher order statistical information obtained using the PF. Methods such as the Principal Component Analysis (PCA) are based on utilizing up to second order statistics, hence will not suffice in maintaining maximum information content. Both the PCA and the ICA are applied to two scenarios that involve a highly eccentric orbit with a lower apriori uncertainty covariance and a less eccentric orbit with a higher a priori uncertainty covariance, to illustrate the capability of the ICA in relation to the PCA.

The Effect of Orbital Configuration on the Possible Climates and Habitability of Kepler-62f.

Science.gov (United States)

Shields, Aomawa L; Barnes, Rory; Agol, Eric; Charnay, Benjamin; Bitz, Cecilia; Meadows, Victoria S

2016-06-01

As lower-mass stars often host multiple rocky planets, gravitational interactions among planets can have significant effects on climate and habitability over long timescales. Here we explore a specific case, Kepler-62f (Borucki et al., 2013 ), a potentially habitable planet in a five-planet system with a K2V host star. N-body integrations reveal the stable range of initial eccentricities for Kepler-62f is 0.00 ≤ e ≤ 0.32, absent the effect of additional, undetected planets. We simulate the tidal evolution of Kepler-62f in this range and find that, for certain assumptions, the planet can be locked in a synchronous rotation state. Simulations using the 3-D Laboratoire de Météorologie Dynamique (LMD) Generic global climate model (GCM) indicate that the surface habitability of this planet is sensitive to orbital configuration. With 3 bar of CO2 in its atmosphere, we find that Kepler-62f would only be warm enough for surface liquid water at the upper limit of this eccentricity range, providing it has a high planetary obliquity (between 60° and 90°). A climate similar to that of modern-day Earth is possible for the entire range of stable eccentricities if atmospheric CO2 is increased to 5 bar levels. In a low-CO2 case (Earth-like levels), simulations with version 4 of the Community Climate System Model (CCSM4) GCM and LMD Generic GCM indicate that increases in planetary obliquity and orbital eccentricity coupled with an orbital configuration that places the summer solstice at or near pericenter permit regions of the planet with above-freezing surface temperatures. This may melt ice sheets formed during colder seasons. If Kepler-62f is synchronously rotating and has an ocean, CO2 levels above 3 bar would be required to distribute enough heat to the nightside of the planet to avoid atmospheric freeze-out and permit a large enough region of open water at the planet's substellar point to remain stable. Overall, we find multiple plausible combinations of

LONG-LIVED CHAOTIC ORBITAL EVOLUTION OF EXOPLANETS IN MEAN MOTION RESONANCES WITH MUTUAL INCLINATIONS

Energy Technology Data Exchange (ETDEWEB)

Barnes, Rory; Deitrick, Russell; Quinn, Thomas R. [Astronomy Department, University of Washington, Box 951580, Seattle, WA 98195 (United States); Greenberg, Richard [Lunar and Planetary Laboratory, University of Arizona, 1629 E. University Boulevard, Tucson, AZ 86716 (United States); Raymond, Sean N., E-mail: rory@astro.washington.edu [NASA Astrobiology Institute-Virtual Planetary Laboratory Lead Team (United States)

2015-03-10

We present N-body simulations of resonant planets with inclined orbits that show chaotically evolving eccentricities and inclinations that can persist for at least 10 Gyr. A wide range of behavior is possible, from fast, low amplitude variations to systems in which eccentricities reach 0.9999 and inclinations 179.°9. While the orbital elements evolve chaotically, at least one resonant argument always librates. We show that the HD 73526, HD 45364, and HD 60532 systems may be in chaotically evolving resonances. Chaotic evolution is apparent in the 2:1, 3:1, and 3:2 resonances, and for planetary masses from lunar- to Jupiter-mass. In some cases, orbital disruption occurs after several gigayears, implying the mechanism is not rigorously stable, just long-lived relative to the main sequence lifetimes of solar-type stars. Planet-planet scattering appears to yield planets in inclined resonances that evolve chaotically in about 0.5% of cases. These results suggest that (1) approximate methods for identifying unstable orbital architectures may have limited applicability, (2) the observed close-in exoplanets may be produced during epochs of high eccentricit induced by inclined resonances, (3) those exoplanets' orbital planes may be misaligned with the host star's spin axis, (4) systems with resonances may be systematically younger than those without, (5) the distribution of period ratios of adjacent planets detected via transit may be skewed due to inclined resonances, and (6) potentially habitable planets may have dramatically different climatic evolution than Earth. The Gaia spacecraft is capable of discovering giant planets in these types of orbits.

LONG-LIVED CHAOTIC ORBITAL EVOLUTION OF EXOPLANETS IN MEAN MOTION RESONANCES WITH MUTUAL INCLINATIONS

International Nuclear Information System (INIS)

Barnes, Rory; Deitrick, Russell; Quinn, Thomas R.; Greenberg, Richard; Raymond, Sean N.

2015-01-01

We present N-body simulations of resonant planets with inclined orbits that show chaotically evolving eccentricities and inclinations that can persist for at least 10 Gyr. A wide range of behavior is possible, from fast, low amplitude variations to systems in which eccentricities reach 0.9999 and inclinations 179.°9. While the orbital elements evolve chaotically, at least one resonant argument always librates. We show that the HD 73526, HD 45364, and HD 60532 systems may be in chaotically evolving resonances. Chaotic evolution is apparent in the 2:1, 3:1, and 3:2 resonances, and for planetary masses from lunar- to Jupiter-mass. In some cases, orbital disruption occurs after several gigayears, implying the mechanism is not rigorously stable, just long-lived relative to the main sequence lifetimes of solar-type stars. Planet-planet scattering appears to yield planets in inclined resonances that evolve chaotically in about 0.5% of cases. These results suggest that (1) approximate methods for identifying unstable orbital architectures may have limited applicability, (2) the observed close-in exoplanets may be produced during epochs of high eccentricit induced by inclined resonances, (3) those exoplanets' orbital planes may be misaligned with the host star's spin axis, (4) systems with resonances may be systematically younger than those without, (5) the distribution of period ratios of adjacent planets detected via transit may be skewed due to inclined resonances, and (6) potentially habitable planets may have dramatically different climatic evolution than Earth. The Gaia spacecraft is capable of discovering giant planets in these types of orbits

Solar radiation pressure resonances in Low Earth Orbits

Science.gov (United States)

Alessi, Elisa Maria; Schettino, Giulia; Rossi, Alessandro; Valsecchi, Giovanni B.

2018-01-01

The aim of this work is to highlight the crucial role that orbital resonances associated with solar radiation pressure can have in Low Earth Orbit. We review the corresponding literature, and provide an analytical tool to estimate the maximum eccentricity which can be achieved for well-defined initial conditions. We then compare the results obtained with the simplified model with the results obtained with a more comprehensive dynamical model. The analysis has important implications both from a theoretical point of view, because it shows that the role of some resonances was underestimated in the past, and also from a practical point of view in the perspective of passive deorbiting solutions for satellites at the end-of-life.

Orbiting objective lens telescope system and method

International Nuclear Information System (INIS)

Crooks, J.W. Jr.

1984-01-01

A large objective lens is placed in a highly eccentric orbit about the earth. The orbit and orientation of the lens are carefully chosen so that it focuses light or other radiation from a preselected astronomical object into an image which slowly moves across the surface of the earth. A row of optical sensing units is located on the surface of the earth so that the image focused by the orbiting objective lens will travel substantially perpendicularly across the row during an observation. Output data generated from the sensing units may be multiplexed and fed to a real time processor which produces display signals. Each of the sensing units provides one scan line of the image being observed. The display signals are fed to a suitable display device which produces a picture of the preselected astronomical object. The objective lens may comprise a large flexible Fresnel zone plate or a flexible convex lens carried by a bicycle wheel-type supporting structure. The lens and supporting structure may be unfolded from compact cargo configurations and rotated after being placed into orbit

A hot Saturn on an eccentric orbit around the giant star K2-132

Science.gov (United States)

Jones, M. I.; Brahm, R.; Espinoza, N.; Jordán, A.; Rojas, F.; Rabus, M.; Drass, H.; Zapata, A.; Soto, M. G.; Jenkins, J. S.; Vučković, M.; Ciceri, S.; Sarkis, P.

2018-06-01

Although the majority of radial velocity detected planets have been found orbiting solar-type stars, a fraction of them have been discovered around giant stars. These planetary systems have revealed different orbital properties when compared to solar-type star companions. In particular, radial velocity surveys have shown that there is a lack of giant planets in close-in orbits around giant stars, in contrast to the known population of hot Jupiters orbiting solar-type stars. It has been theorized that the reason for this distinctive feature in the semimajor axis distribution is the result of the stellar evolution and/or that it is due to the effect of a different formation/evolution scenario for planets around intermediate-mass stars. However, in the past few years a handful of transiting short-period planets (P ≲ 10 days) have been found around giant stars, thanks to the high-precision photometric data obtained initially by the Kepler mission, and later by its two-wheel extension K2. These new discoveries have allowed us for the first time to study the orbital properties and physical parameters of these intriguing and elusive substellar companions. In this paper we report on an independent discovery of a transiting planet in field 10 of the K2 mission, also reported recently by Grunblatt et al. (2017, AJ, 154, 254). The host star has recently evolved to the giant phase, and has the following atmospheric parameters: Teff = 4878 ± 70 K, log g = 3.289 ± 0.004, and [Fe/H] = -0.11 ± 0.05 dex. The main orbital parameters of K2-132 b, obtained with all the available data for the system are: P = 9.1708 ± 0.0025 d, e = 0.290 ± 0.049, Mp = 0.495 ± 0.007 MJ and Rp = 1.089 ± 0.006 RJ. This is the fifth known planet orbiting any giant star with a K2-132 b a very interesting object. Tables of the photometry and of the radial velocities are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http

Driving dynamic colloidal assembly using eccentric self-propelled colloids

OpenAIRE

Ma, Zhan; Lei, Qun-li; Ni, Ran

2017-01-01

Designing protocols to dynamically direct the self-assembly of colloidal particles has become an important direction in soft matter physics because of the promising applications in fabrication of dynamic responsive functional materials. Here using computer simulations, we found that in the mixture of passive colloids and eccentric self-propelled active particles, when the eccentricity and self-propulsion of active particles are high enough, the eccentric active particles can push passive coll...

The features of sporadic hyperbolic meteors observed by television techniques in the period of 2007-2009

Science.gov (United States)

Guliyev, Ayyub; Nabiyev, Shaig

2015-12-01

The features of 238 hyperbolic meteors observed within the framework of the Japanese program SonotaCo in the period of 2007-2009 are investigated in this paper. Irregularity of the eccentricities, explicitly dominance of retrograde orbits over direct ones, absence of domination of perihelia closes the ecliptic, irregular distribution of angular elements for these bodies' orbits were noticed. The values of eccentricities are distributed in the interval from 1 up to 1.31. The significant concentration of these particles perihelia closes the anti-apex of the Sun's peculiarity movements in the Galaxy was noticed. Distribution of elements of orbits in the galactic system of coordinates was considered also, however it was not possible to find the appreciable regularities. The distributions of the distant nodes and MOID-Minimum Orbit Intersection Distance of the hyperbolic meteors relatively to the orbits of the planets-giants were investigated as well. However it was not possible to prove, that the majority of the particles could receive the hyperbolic excess of speed due to the gravitational influence of the planets-giants. The statistics of relation of the hyperbolic meteors with 14 known trans-Neptunian planetary bodies brighter 3m.5 is considered. Testing of the distant nodes and MOID values only for 2003 MW12, 2007 OR10 and Qaoaor have the positive results. In the next stage we have made analogical calculations for the 78 TNO having absolute brightness 5m.5 also and obtained the reasonable results for 9 of them.

[Systematic review about eccentric training in chronic patella tendinopathy].

Science.gov (United States)

Lorenzen, J; Krämer, R; Vogt, P M; Knobloch, K

2010-12-01

Eccentric training has become a popular treatment for patellar tendinopathy. Aim of this review is to display different exercise prescriptions for patellar tendinopathy, to help clinicians make appropriate choices and identify areas needing further research. Is eccentric training as a conservative treatment in chronic patellar tendinopathy of beneficial effect versus other conservative treatments? According to the current scientific data, is it possible to recommend dosages and duration of training time of eccentric training? Systematic review of the current scientific literature on eccentric training as a conservative treatment in chronic Achilles tendinopathy according to the PRISMA-guidelines [Preferred Reporting Items for Systematic Reviews and Meta-Analyses]. National library of Medicine [NLM] between the years 1950 and 2010. Prospective randomised controlled trials (RCT). 7 articles with a total of 165 patients and in which eccentric training was one of the interventions, all published after 2000, were included. The median cohort study size was 20 subjects with a range from 15 to 35 subjects. Median follow-up duration was 12 weeks with a range from 4 to 12 weeks. Encouraging results, but variable study quality, with small numbers or short follow-up periods. The content of the different training programmes varied, but most were home-based programmes with twice daily training for 12 weeks. A number of potentially significant differences were identified in the eccentric programmes used: drop squats or slow eccentric movement, squatting on a 25° decline board or level ground, exercising into tendon pain or short of pain, loading the eccentric phase only or both phases, and progressing with speed then loading or simply loading. A pooled statistical evaluation of the included trials could not be performed due to different study designs as well as limited documentation of subjects' compliance. Most studies suggest that eccentric training may have a positive effect

Normative values of eccentric hip abduction strength in novice runners

DEFF Research Database (Denmark)

Ramskov, D; Pedersen, M B; Kastrup, K

2014-01-01

normative values of maximal eccentric hip abduction strength in novice runners. METHODS: Novice healthy runners (n = 831) were recruited through advertisements at a hospital and a university. Maximal eccentric hip abduction strength was measured with a hand-held dynamometer. The demographic variables...... was found, p values were identified using a regression equation adjusting for age and gender. Based on this, the equation to calculate normative values for relative eccentric hip abduction strength became: (1.600 + (age * -0.005) + (gender (1 = male / 0 = female) * 0.215) ± 1 or 2 * 0......PURPOSE: Low eccentric strength of the hip abductors, might increase the risk of patellofemoral pain syndrome and iliotibial band syndrome in runners. No normative values for maximal eccentric hip abduction strength have been established. Therefore the purpose of this study was to establish...

Independent predictors of retrograde failure in CTO-PCI after successful collateral channel crossing.

Science.gov (United States)

Suzuki, Yoriyasu; Muto, Makoto; Yamane, Masahisa; Muramatsu, Toshiya; Okamura, Atsunori; Igarashi, Yasumi; Fujita, Tsutomu; Nakamura, Shigeru; Oida, Akitsugu; Tsuchikane, Etsuo

2017-07-01

To evaluate factors for predicting retrograde CTO-PCI failure after successful collateral channel crossing. Successful guidewire/catheter collateral channel crossing is important for the retrograde approach in percutaneous coronary intervention (PCI) for chronic total occlusion (CTO). A total of 5984 CTO-PCI procedures performed in 45 centers in Japan from 2009 to 2012 were studied. The retrograde approach was used in 1656 CTO-PCIs (27.7%). We investigated these retrograde procedures to evaluate factors for predicting retrograde CTO-PCI failure even after successful collateral channel crossing. Successful guidewire/catheter collateral crossing was achieved in 77.1% (n = 1,276) of 1656 retrograde CTO-PCI procedures. Retrograde procedural success after successful collateral crossing was achieved in 89.4% (n = 1,141). Univariate analysis showed that the predictors for retrograde CTO-PCI failure were in-stent occlusion (OR = 1.9829, 95%CI = 1.1783 - 3.3370 P = 0.0088), calcified lesions (OR = 1.9233, 95%CI = 1.2463 - 2.9679, P = 0.0027), and lesion tortuosity (OR = 1.5244, 95%CI = 1.0618 - 2.1883, P = 0.0216). On multivariate analysis, lesion calcification was an independent predictor of retrograde CTO-PCI failure after successful collateral channel crossing (OR = 1.3472, 95%CI = 1.0614 - 1.7169, P = 0.0141). The success rate of retrograde CTO-PCI following successful guidewire/catheter collateral channel crossing was high in this registry. Lesion calcification was an independent predictor of retrograde CTO-PCI failure after successful collateral channel crossing. Devices and techniques to overcome complex CTO lesion morphology, such as lesion calcification, are required to further improve the retrograde CTO-PCI success rate. © 2016 Wiley Periodicals, Inc. © 2016 Wiley Periodicals, Inc.

Response of electrostatic probes to eccentric charge distributions

DEFF Research Database (Denmark)

Johansson, Torben; McAllister, Iain Wilson

2001-01-01

The response of an electrostatic probe mounted in an electrode is examined with reference to eccentric charge distributions. The study involves using the probe λ function to derive a characteristic parameter. This parameter enables the response of the probe to different degrees of eccentricity...

Retrograde amnesia for semantic information in Alzheimer’s disease

NARCIS (Netherlands)

Meeter, M.; Knollen, A.; Scheltens, P.

2005-01-01

Patients with mild to moderate Alzheimer's disease and normal controls were tested on a retrograde amnesia test with semantic content (Neologism and Vocabulary Test, or NVT), consisting of neologisms to be defined. Patients showed a decrement as compared to normal controls, pointing to retrograde

Mercury Retrograde Effect in Capital Markets: Truth or Illusion?

Directory of Open Access Journals (Sweden)

Murgea Aurora

2016-06-01

Full Text Available From the most ancient times, the astrological beliefs have played an important role in human history, thinking, world-views, language and other elements of social culture. The practice of relating the movement of celestial bodies to events in financial markets is relatively newer but despite the inconsistency between financial astrology and standard economic or financial theory, it seems to be largely spread among capital market traders. This paper evaluates one of the astrological effects on the capital market, more precisely the Mercury retrograde effect on US capital market. Despite the fact that it is just an optical illusion the astrological tradition says that Mercury retrograde periods are characterized by confusion and miscommunications. The trades could be less effective, the individuals more prone to make mistakes so there is a long-held belief that it is better to avoid set plans during Mercury retrograde, signing contracts, starting new ventures or open new stock market positions. The main findings of this study are lower return’s volatilities in the Mercury retrograde periods, inconsistent with the astrologic theories assumptions but consistent with the idea that trader’s beliefs in Mercury retrograde effect could change the market volatility exactly in the opposite sense than the predicted one.

Formation flying for electric sails in displaced orbits. Part I: Geometrical analysis

Science.gov (United States)

Wang, Wei; Mengali, Giovanni; Quarta, Alessandro A.; Yuan, Jianping

2017-09-01

We present a geometrical methodology for analyzing the formation flying of electric solar wind sail based spacecraft that operate in heliocentric, elliptic, displaced orbits. The spacecraft orbit is maintained by adjusting its propulsive acceleration modulus, whose value is estimated using a thrust model that takes into account a variation of the propulsive performance with the sail attitude. The properties of the relative motion of the spacecraft are studied in detail and a geometrical solution is obtained in terms of relative displaced orbital elements, assumed to be small quantities. In particular, for the small eccentricity case (i.e. for a near-circular displaced orbit), the bounds characterized by the extreme values of relative distances are analytically calculated, thus providing an useful mathematical tool for preliminary design of the spacecraft formation structure.

Metrics in Keplerian orbits quotient spaces

Science.gov (United States)

Milanov, Danila V.

2018-03-01

Quotient spaces of Keplerian orbits are important instruments for the modelling of orbit samples of celestial bodies on a large time span. We suppose that variations of the orbital eccentricities, inclinations and semi-major axes remain sufficiently small, while arbitrary perturbations are allowed for the arguments of pericentres or longitudes of the nodes, or both. The distance between orbits or their images in quotient spaces serves as a numerical criterion for such problems of Celestial Mechanics as search for common origin of meteoroid streams, comets, and asteroids, asteroid families identification, and others. In this paper, we consider quotient sets of the non-rectilinear Keplerian orbits space H. Their elements are identified irrespective of the values of pericentre arguments or node longitudes. We prove that distance functions on the quotient sets, introduced in Kholshevnikov et al. (Mon Not R Astron Soc 462:2275-2283, 2016), satisfy metric space axioms and discuss theoretical and practical importance of this result. Isometric embeddings of the quotient spaces into R^n, and a space of compact subsets of H with Hausdorff metric are constructed. The Euclidean representations of the orbits spaces find its applications in a problem of orbit averaging and computational algorithms specific to Euclidean space. We also explore completions of H and its quotient spaces with respect to corresponding metrics and establish a relation between elements of the extended spaces and rectilinear trajectories. Distance between an orbit and subsets of elliptic and hyperbolic orbits is calculated. This quantity provides an upper bound for the metric value in a problem of close orbits identification. Finally the invariance of the equivalence relations in H under coordinates change is discussed.

Influence of tides in viscoelastic bodies of planet and satellite on the satellite's orbital motion

Science.gov (United States)

Emelyanov, N. V.

2018-06-01

The problem of influence of tidal friction in both planetary and satellite bodies upon satellite's orbital motion is considered. Using the differential equations in satellite's rectangular planetocentric coordinates, the differential equations describing the changes in semimajor axis and eccentricity are derived. The equations in rectangular coordinates were taken from earlier works on the problem. The calcultations carried out for a number of test examples prove that the averaged solutions of equations in coordinates and precise solutions of averaged equations in the Keplerian elements are identical. For the problem of tides raised on planet's body, it was found that, if satellite's mean motion n is equal to 11/18 Ω, where Ω is the planet's angular rotation rate, the orbital eccentricity does not change. This conclusion is in agreement with the results of other authors. It was also found that there is essential discrepancy between the equations in the elements obtained in this paper and analogous equations published by earlier researchers.

Increased sinusoidal volume and solute extraction during retrograde liver perfusion

International Nuclear Information System (INIS)

Bass, N.M.; Manning, J.A.; Weisiger, R.A.

1989-01-01

Retrograde isolated liver perfusion has been used to probe acinar functional heterogeneity, but the hemodynamic effects of backward flow have not been characterized. In this study, extraction of a long-chain fatty acid derivative, 12-N-methyl-7-nitrobenzo-2-oxa-1,3-diazol-amino stearate (12-NBDS), was greater during retrograde than during anterograde perfusion of isolated rat liver. To determine whether hemodynamic differences between anterograde and retrograde perfused livers could account for this finding, the hepatic extracellular space was measured for both directions of flow by means of [ 14 C]sucrose washout during perfusion as well as by direct measurement of [ 14 C]sucrose entrapped during perfusion. A three- to fourfold enlargement of the total hepatic extracellular space was found during retrograde perfusion by both approaches. Examination of perfusion-fixed livers by light microscopy and morphometry revealed that marked distension of the sinusoids occurred during retrograde perfusion and that this accounts for the observed increase in the [ 14 C]sucrose space. These findings support the hypothesis that maximum resistance to perfusate flow in the isolated perfused rat liver is located at the presinusoidal level. In addition, increased transit time of perfusate through the liver and greater sinusoidal surface area resulting from sinusoidal distension may account for the higher extraction of 12-NBDS and possibly other compounds by retrograde perfused liver

Brain activation associated with eccentric movement: A narrative review of the literature.

Science.gov (United States)

Perrey, Stéphane

2018-02-01

The movement occurring when a muscle exerts tension while lengthening is known as eccentric muscle action. Literature contains limited evidence on how our brain controls eccentric movement. However, how the cortical regions in the motor network are activated during eccentric muscle actions may be critical for understanding the underlying control mechanism of eccentric movements encountered in daily tasks. This is a novel topic that has only recently begun to be investigated through advancements in neuroimaging methods (electroencephalography, EEG; functional magnetic resonance imaging, fMRI). This review summarizes a selection of seven studies indicating mainly: longer time and higher cortical signal amplitude (EEG) for eccentric movement preparation and execution, greater magnitude of cortical signals with wider activated brain area (EEG, fMRI), and weaker brain functional connectivity (fMRI) between primary motor cortex (M1) and other cortical areas involved in the motor network during eccentric muscle actions. Only some differences among studies due to the forms of movement with overload were observed in the contralateral (to the active hand) M1 activity during eccentric movement. Altogether, the findings indicate an important challenge to the brain for controlling the eccentric movement. However, our understanding remains limited regarding the acute effects of eccentric exercise on cortical regions and their cooperation as functional networks that support motor functions. Further analysis and standardized protocols will provide deeper insights into how different cortical regions of the underlying motor network interplay with each other in increasingly demanding muscle exertions in eccentric mode.

Kinematics of turnaround and retrograde axonal transport

International Nuclear Information System (INIS)

Snyder, R.E.

1986-01-01

Rapid axonal transport of a pulse of 35 S-methionine-labelled material was studied in vitro in the sensory neurons of amphibian sciatic nerve using a position-sensitive detector. For 10 nerves studied at 23.0 +/- 0.2 degrees C it was found that a pulse moved in the anterograde direction characterized by front edge, peak, and trailing edge transport rates of (mm/d) 180.8 +/- 2.2 (+/- SEM), 176.6 +/- 2.3, and 153.7 +/- 3.0, respectively. Following its arrival at a distal ligature, a smaller pulse was observed to move in the retrograde direction characterized by front edge and peak transport rates of 158.0 +/- 7.3 and 110.3 +/- 3.5, respectively, indicating that retrograde transport proceeds at a rate of 0.88 +/- 0.04 that of anterograde. The retrograde pulse was observed to disperse at a rate greater than the anterograde. Reversal of radiolabel at the distal ligature began 1.49 +/- 0.15 h following arrival of the first radiolabel. Considerable variation was seen between preparations in the way radiolabel accumulated in the end (ligature) regions of the nerve. Although a retrograde pulse was seen in all preparations, in 7 of 10 preparations there was no evidence of this pulse accumulating within less than 2-3 mm of a proximal ligature; however, accumulation was observed within less than 5 mm in all preparations

Design and jump phenomenon analysis of an eccentric ring energy harvester

International Nuclear Information System (INIS)

Wang, Yu-Jen; Chen, Chung-De

2013-01-01

This paper presents the development of a wheel-mounted eccentric ring energy harvester that is driven by centripetal and gravitational forces during wheel rotation. The natural frequency of the eccentric ring matches the wheel rotation frequency at any car speed because its character length is designed equal to the wheel radius. Consequently, the eccentric ring oscillates with a relatively large swing angle at the wheel speed to generate high levels of power. The nonlinear dynamic behavior of the eccentric ring is investigated to ensure that the proposed design produces steady swing angles, especially at high wheel speeds. Herein, the jump phenomenon of the dynamic motion of the eccentric ring is analyzed by using the Duffing equation and the linearization process. The discriminant value obtained from the analysis confirms that no jump phenomenon occurs at all wheel speeds if the eccentric ring is properly designed. In the experiment, the eccentric ring is integrated with magnets and a coil set to generate 318–442 μW at constant wheel speeds between 300 and 500 rpm. This shows that the proposed device is a potential power source for low-power wheel-mounted electronics, such as pressure sensors, accelerometers, and thermometers. (paper)

Design and jump phenomenon analysis of an eccentric ring energy harvester

Science.gov (United States)

Wang, Yu-Jen; Chen, Chung-De

2013-10-01

This paper presents the development of a wheel-mounted eccentric ring energy harvester that is driven by centripetal and gravitational forces during wheel rotation. The natural frequency of the eccentric ring matches the wheel rotation frequency at any car speed because its character length is designed equal to the wheel radius. Consequently, the eccentric ring oscillates with a relatively large swing angle at the wheel speed to generate high levels of power. The nonlinear dynamic behavior of the eccentric ring is investigated to ensure that the proposed design produces steady swing angles, especially at high wheel speeds. Herein, the jump phenomenon of the dynamic motion of the eccentric ring is analyzed by using the Duffing equation and the linearization process. The discriminant value obtained from the analysis confirms that no jump phenomenon occurs at all wheel speeds if the eccentric ring is properly designed. In the experiment, the eccentric ring is integrated with magnets and a coil set to generate 318-442 μW at constant wheel speeds between 300 and 500 rpm. This shows that the proposed device is a potential power source for low-power wheel-mounted electronics, such as pressure sensors, accelerometers, and thermometers.

Efficient orbit integration by manifold correction methods.

Science.gov (United States)

Fukushima, Toshio

2005-12-01

Triggered by a desire to investigate, numerically, the planetary precession through a long-term numerical integration of the solar system, we developed a new formulation of numerical integration of orbital motion named manifold correct on methods. The main trick is to rigorously retain the consistency of physical relations, such as the orbital energy, the orbital angular momentum, or the Laplace integral, of a binary subsystem. This maintenance is done by applying a correction to the integrated variables at each integration step. Typical methods of correction are certain geometric transformations, such as spatial scaling and spatial rotation, which are commonly used in the comparison of reference frames, or mathematically reasonable operations, such as modularization of angle variables into the standard domain [-pi, pi). The form of the manifold correction methods finally evolved are the orbital longitude methods, which enable us to conduct an extremely precise integration of orbital motions. In unperturbed orbits, the integration errors are suppressed at the machine epsilon level for an indefinitely long period. In perturbed cases, on the other hand, the errors initially grow in proportion to the square root of time and then increase more rapidly, the onset of which depends on the type and magnitude of the perturbations. This feature is also realized for highly eccentric orbits by applying the same idea as used in KS-regularization. In particular, the introduction of time elements greatly enhances the performance of numerical integration of KS-regularized orbits, whether the scaling is applied or not.

Lengthening our perspective: morphological, cellular, and molecular responses to eccentric exercise.

Science.gov (United States)

Hyldahl, Robert D; Hubal, Monica J

2014-02-01

The response of skeletal muscle to unaccustomed eccentric exercise has been studied widely, yet it is incompletely understood. This review is intended to provide an up-to-date overview of our understanding of how skeletal muscle responds to eccentric actions, with particular emphasis on the underlying molecular and cellular mechanisms of damage and recovery. This review begins by addressing the question of whether eccentric actions result in physical damage to muscle fibers and/or connective tissue. We next review the symptomatic manifestations of eccentric exercise (i.e., indirect damage markers, such as delayed onset muscle soreness), with emphasis on their relatively poorly understood molecular underpinnings. We then highlight factors that potentially modify the muscle damage response following eccentric exercise. Finally, we explore the utility of using eccentric training to improve muscle function in populations of healthy and aging individuals, as well as those living with neuromuscular disorders. Copyright © 2013 Wiley Periodicals, Inc.

The Smaller Alignment Index (SALI) applied in a study of stellar orbits in barred galaxies potential models using the LP-VIcode

Science.gov (United States)

Caritá, Lucas Antonio; Rodrigues, Irapuan; Puerari, Ivânio; Schiavo, Luiz Eduardo Camargo Aranha

2018-04-01

The Smaller Alignment Index (SALI) is a mathematical tool, not yet conventional, for chaos detection in the phase space of Hamiltonian Dynamical Systems. The SALI values has temporal behaviors very specific to ordered or chaotic motions, what makes the distinction between order and chaos easily observable in these systems. In this paper, this method will be applied to the stability study of stellar orbits immersed in gravitational potential of barred galaxies, since the motion of a test particle in a rotating barred galaxy model is given by a Hamiltonian function. Extracting four parameter sets from the Manos and Athanassoula (2011) work and elaborating a different initial conditions set for each case, we were able to introduce another point of view of their stability study for two degrees of freedom. We have also introduced two new extreme models that corroborates with the conclusions that more axisymmetric bars create an environment with less chaos and that more massive bars create an environment with more chaos. Separate studies were carried out for prograde and retrograde orbits that showed that the retrograde orbits seem more conducive to chaos. To perform all the orbits integrations we used the LP-VIcode program.

A CAUTIONARY TALE: MARVELS BROWN DWARF CANDIDATE REVEALS ITSELF TO BE A VERY LONG PERIOD, HIGHLY ECCENTRIC SPECTROSCOPIC STELLAR BINARY

Energy Technology Data Exchange (ETDEWEB)

Mack, Claude E. III; Stassun, Keivan G.; De Lee, Nathan [Department of Physics and Astronomy, Vanderbilt University, Nashville, TN 37235 (United States); Ge, Jian; Fleming, Scott W. [Department of Astronomy, University of Florida, 211 Bryant Space Science Center, Gainesville, FL, 32611-2055 (United States); Deshpande, Rohit; Mahadevan, Suvrath [Department of Astronomy and Astrophysics, The Pennsylvania State University, 525 Davey Laboratory, University Park, PA 16802 (United States); Wisniewski, John P. [Homer L Dodge Department of Physics and Astronomy, University of Oklahoma, 440 W Brooks St, Norman, OK 73019 (United States); Gaudi, B. Scott; Eastman, Jason; Beatty, Thomas G. [Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210 (United States); Ghezzi, Luan [Observatorio Nacional, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ 20921-400 (Brazil); Gonzalez Hernandez, Jonay I.; Femenia, Bruno; Mata Sanchez, Daniel [Instituto de Astrofisica de Canarias (IAC), E-38205 La Laguna, Tenerife (Spain); Ferreira, Leticia; Porto de Mello, Gustavo [Laboratorio Interinstitucional de e-Astronomia-LIneA, Rua Gal. Jose Cristino 77, Rio de Janeiro, RJ 20921-400 (Brazil); Crepp, Justin R. [Department of Physics, University of Notre Dame, 225 Nieuwland Science Hall, Notre Dame, IN 46556 (United States); Agol, Eric [Astronomy Department, University of Washington, Box 351580, Seattle, WA 98195 (United States); Bizyaev, Dmitry, E-mail: claude.e.mack@vanderbilt.edu [Apache Point Observatory, P.O. Box 59, Sunspot, NM 88349-0059 (United States); and others

2013-05-15

We report the discovery of a highly eccentric, double-lined spectroscopic binary star system (TYC 3010-1494-1), comprising two solar-type stars that we had initially identified as a single star with a brown dwarf companion. At the moderate resolving power of the MARVELS spectrograph and the spectrographs used for subsequent radial-velocity (RV) measurements (R {approx}< 30, 000), this particular stellar binary mimics a single-lined binary with an RV signal that would be induced by a brown dwarf companion (Msin i {approx} 50 M{sub Jup}) to a solar-type primary. At least three properties of this system allow it to masquerade as a single star with a very-low-mass companion: its large eccentricity (e {approx} 0.8), its relatively long period (P {approx} 238 days), and the approximately perpendicular orientation of the semi-major axis with respect to the line of sight ({omega} {approx} 189 Degree-Sign ). As a result of these properties, for {approx}95% of the orbit the two sets of stellar spectral lines are completely blended, and the RV measurements based on centroiding on the apparently single-lined spectrum is very well fit by an orbit solution indicative of a brown dwarf companion on a more circular orbit (e {approx} 0.3). Only during the {approx}5% of the orbit near periastron passage does the true, double-lined nature and large RV amplitude of {approx}15 km s{sup -1} reveal itself. The discovery of this binary system is an important lesson for RV surveys searching for substellar companions; at a given resolution and observing cadence, a survey will be susceptible to these kinds of astrophysical false positives for a range of orbital parameters. Finally, for surveys like MARVELS that lack the resolution for a useful line bisector analysis, it is imperative to monitor the peak of the cross-correlation function for suspicious changes in width or shape, so that such false positives can be flagged during the candidate vetting process.

The loss of episodic memories in retrograde amnesia: single-case and group studies.

OpenAIRE

Kopelman, M D; Kapur, N

2001-01-01

Retrograde amnesia in neurological disorders is a perplexing and fascinating research topic. The severity of retrograde amnesia is not well correlated with that of anterograde amnesia, and there can be disproportionate impairments of either. Within retrograde amnesia, there are various dissociations which have been claimed-for example, between the more autobiographical (episodic) and more semantic components of memory. However, the associations of different types of retrograde amnesia are als...

Tatooines Future: The Eccentric Response of Keplers Circumbinary Planets to Common-Envelope Evolution of their Host Stars

Science.gov (United States)

Kostov, Veselin B.; Moore, Keavin; Tamayo, Daniel; Jayawardhana, Ray; Rinehart, Stephen A.

2016-01-01

Inspired by the recent Kepler discoveries of circumbinary planets orbiting nine close binary stars, we explore the fate of the former as the latter evolve off the main sequence. We combine binary star evolution models with dynamical simulations to study the orbital evolution of these planets as their hosts undergo common-envelope stages, losing in the process a tremendous amount of mass on dynamical timescales. Five of the systems experience at least one Roche-lobe overflow and common-envelope stages (Kepler-1647 experiences three), and the binary stars either shrink to very short orbits or coalesce; two systems trigger a double-degenerate supernova explosion. Kepler's circumbinary planets predominantly remain gravitationally bound at the end of the common-envelope phase, migrate to larger orbits, and may gain significant eccentricity; their orbital expansion can be more than an order of magnitude and can occur over the course of a single planetary orbit. The orbits these planets can reach are qualitatively consistent with those of the currently known post-common-envelope, eclipse-time variations circumbinary candidates. Our results also show that circumbinary planets can experience both modes of orbital expansion (adiabatic and non-adiabatic) if their host binaries undergo more than one common-envelope stage; multiplanet circumbinary systems like Kepler-47 can experience both modes during the same common-envelope stage. Additionally, unlike Mercury orbiting the Sun, a circumbinary planet with the same semi-major axis can survive the common envelope evolution of a close binary star with a total mass of 1 Solar Mass.

Conformation radiotherapy with eccentric multi-leaves, (1)

International Nuclear Information System (INIS)

Obata, Yasunori; Sakuma, Sadayuki.

1986-01-01

In order to extend the application of the conformation radiotherapy, the eccentric multi-leaves are equipped with the linear accelerator. The information of the position of the collimators and the dose distribution of the eccentric conformation radiotherapy are calculated by the improved algorism of the treatment planning system. In simple cases, the dose distributions for the distant region from the rotational center are measured and compared with the calculated values. Both distributions are well coincided with the error of about 5 % in the high dose region and 10 % in the low dose region. In eccentric conformation radiotherapy, it is difficult to deliver the planned dose to the lesion. The dose increases with the distance of the target area from the rotational center. And the measured value and the calculated value are well coincided with 1 % error. So after getting the dose ratio of the rotational center to the target area, the calculated dose can be delivered to the rotational center. The advantages of the eccentric conformation radiotherapy are a good coincidence of target area and treated area, a partial shielding and a hollow out technique without absorber. The limitation of the movement of the collimator from center is 5 cm at 1 m SCD. (author)

Transverse and Longitudinal Doppler Effects of the Sunbeam Spectra and Earth-Self Rotation and Orbital Velocities, the Mass of the Sun and Others

OpenAIRE

Nam, Sang Boo

2009-01-01

The transverse and longitudinal Doppler effects of the sunbeam spectra are shown to result in the earth parameters such as the earth-self rotation and revolution velocities, the earth orbit semi-major axis, the earth orbital angular momentum, the earth axial tilt, the earth orbit eccentricity, the local latitude and the mass of the sun. The sunbeam global positioning scheme is realized, including the earth orbital position. PACS numbers: 91.10.Fc, 95.10.Km, 91.10.Da, 91.10.Jf.

Retrograde Transvenous Ethanol Embolization of High-flow Peripheral Arteriovenous Malformations

International Nuclear Information System (INIS)

Linden, Edwin van der; Baalen, Jary M. van; Pattynama, Peter M. T.

2012-01-01

Purpose: To report the clinical efficiency and complications in patients treated with retrograde transvenous ethanol embolization of high-flow peripheral arteriovenous malformations (AVMs). Retrograde transvenous ethanol embolization of high-flow AVMs is a technique that can be used to treat AVMs with a dominant outflow vein whenever conventional interventional procedures have proved insufficient. Methods: This is a retrospective study of the clinical effectiveness and complications of retrograde embolization in five patients who had previously undergone multiple arterial embolization procedures without clinical success. Results: Clinical outcomes were good in all patients but were achieved at the cost of serious, although transient, complications in three patients. Conclusion: Retrograde transvenous ethanol embolization is a highly effective therapy for high-flow AVMs. However, because of the high complication rate, it should be reserved as a last resort, to be used after conventional treatment options have failed.

The “SAFARI” Technique Using Retrograde Access Via Peroneal Artery Access

International Nuclear Information System (INIS)

Zhuang, Kun Da; Tan, Seck Guan; Tay, Kiang Hiong

2012-01-01

The “SAFARI” technique or subintimal arterial flossing with antegrade–retrograde intervention is a method for recanalisation of chronic total occlusions (CTOs) when subintimal angioplasty fails. Retrograde access is usually obtained via the popliteal, distal anterior tibial artery (ATA)/dorsalis pedis (DP), or distal posterior tibial artery (PTA). Distal access via the peroneal artery has not been described and has a risk of continued bleeding, leading to compartment syndrome due to its deep location. We describe our experience in two patients with retrograde access via the peroneal artery and the use of balloon-assisted hemostasis for these retrograde punctures. This approach may potentially give more options for endovascular interventions in lower limb CTOs.

Achilles tendon of wistar rats treated with laser therapy and eccentric exercise

OpenAIRE

Souza, Maria Verônica de; Silva, Carlos Henrique Osório; Silva, Micheline Ozana da; Costa, Marcela Bueno Martins da; Dornas, Raul Felipe; Borges, Andréa Pacheco Batista; Natali, Antônio José

2015-01-01

ABSTRACTIntroduction:Both laser therapy and eccentric exercises are used in tendon injuries. However, the association of these physiotherapeutic modalities is yet little investigated.Objective:To evaluate the effect of low-level laser therapy associated to eccentric exercise (downhill walking) on Achilles tendinopathy of Wistar rats.Method:Eighteen Achilles tendon from 15 adult male Wistar rats were used. Tendons were distributed in six groups (laser, eccentric exercise, laser and eccentric e...

Comparing the effects of eccentric training with eccentric training and static stretching exercises in the treatment of patellar tendinopathy. A controlled clinical trial.

Science.gov (United States)

Dimitrios, Stasinopoulos; Pantelis, Manias; Kalliopi, Stasinopoulou

2012-05-01

The aim of the present study was to investigate the effectiveness of eccentric training and eccentric training with static stretching exercises in the management of patellar tendinopathy. Controlled clinical trial. Rheumatology and rehabilitation centre. Forty-three patients who had patellar tendinopathy for at least three months. They were allocated to two groups by alternative allocation. Group A (n = 22) was treated with eccentric training of patellar tendon and static stretching exercises of quadriceps and hamstrings and Group B (n = 21) received eccentric training of patellar tendon. All patients received five treatments per week for four weeks. Pain and function were evaluated using the VISA-P score at baseline, at the end of treatment (week 4), and six months (week 24) after the end of treatment. At the end of treatment, there was a rise in VISA-P score in both groups compared with baseline (Peccentric training and static stretching exercises produced the largest effect (PEccentric training and static stretching exercises is superior to eccentric training alone to reduce pain and improve function in patients with patellar tendinopathy at the end of the treatment and at follow-up.

Eccentric exercise in treatment of Achilles tendinopathy

DEFF Research Database (Denmark)

Nørregaard, J; Larsen, C C; Bieler, T

2007-01-01

Prognosis and treatment of Achilles tendon pain (achillodynia) has been insufficiently studied. The purpose of the present study was to examine the long-term effect of eccentric exercises compared with stretching exercises on patients with achillodynia.......Prognosis and treatment of Achilles tendon pain (achillodynia) has been insufficiently studied. The purpose of the present study was to examine the long-term effect of eccentric exercises compared with stretching exercises on patients with achillodynia....

Eccentric exercise: mechanisms and effects when used as training regime or training adjunct.

Science.gov (United States)

Vogt, Michael; Hoppeler, Hans H

2014-06-01

The aim of the current review is to discuss applications and mechanism of eccentric exercise in training regimes of competitive sports. Eccentric muscle work is important in most sports. Eccentric muscle contractions enhance the performance during the concentric phase of stretch-shortening cycles, which is important in disciplines like sprinting, jumping, throwing, and running. Muscles activated during lengthening movements can also function as shock absorbers, to decelerate during landing tasks or to precisely deal with high external loading in sports like alpine skiing. The few studies available on trained subjects reveal that eccentric training can further enhance maximal muscle strength and power. It can further optimize muscle length for maximal tension development at a greater degree of extension, and has potential to improve muscle coordination during eccentric tasks. In skeletal muscles, these functional adaptations are based on increases in muscle mass, fascicle length, number of sarcomeres, and cross-sectional area of type II fibers. Identified modalities for eccentric loading in athletic populations involve classical isotonic exercises, accentuated jumping exercises, eccentric overloading exercises, and eccentric cycle ergometry. We conclude that eccentric exercise offers a promising training modality to enhance performance and to prevent injuries in athletes. However, further research is necessary to better understand how the neuromuscular system adapts to eccentric loading in athletes. Copyright © 2014 the American Physiological Society.

Brown dwarfs in retrogradely precessing cataclysmic variables?

Directory of Open Access Journals (Sweden)

Martin E.L.

2011-07-01

Full Text Available We compare Smoothed Particle Hydrodynamic simulations of retrogradely precessing accretion disks that have a white dwarf primary and a main sequence secondary with observational data and with theory on retrograde precession via tidal torques like those by the Moon and the Sun on the Earth [1, 2]. Assuming the primary does not accrete much of the mass lost from the secondary, we identify the theoretical low mass star/brown dwarf boundary. We find no observational candidates in our study that could qualify as brown dwarfs.

Fluoroscopically guided pyeloureteral interventions using a retrograde perurethral approach

International Nuclear Information System (INIS)

Amendola, M.A.; Banner, M.P.; Pollack, H.M.; Gordon, R.L.; Van Arsdalen, K.N.

1987-01-01

Employing standard interventional equipment, fluoroscopy, and partially or completely inserted ureteral catheters for access, the authors performed 168 perurethral interventional procedures since 1985. Procedures have included insertion of double (n = 42) or single pigtail stents (n = 47), advancement of retrograde ureteral catheters with or without displacement of a ureteral stone to the renal pelvis (n = 42), urothelial biopsy (n = 30), balloon dilation of ureteral structures (n = 3), ureteral stone extraction (n = 1), and conversion of retrograde to antegrade catheters for balloon dilation of ureteropelvic junction strictures (n = 3). This retrograde approach often obviates the need for antegrade interventional procedures (including percutaneous nephrostomy and ureteral stenting), ureteroscopy, or surgery. Indications, techniques, pitfalls, and complications are illustrated

Motor unit activity after eccentric exercise and muscle damage in humans.

Science.gov (United States)

Semmler, J G

2014-04-01

It is well known that unaccustomed eccentric exercise leads to muscle damage and soreness, which can produce long-lasting effects on muscle function. How this muscle damage influences muscle activation is poorly understood. The purpose of this brief review is to highlight the effect of eccentric exercise on the activation of muscle by the nervous system, by examining the change in motor unit activity obtained from surface electromyography (EMG) and intramuscular recordings. Previous research shows that eccentric exercise produces unusual changes in the EMG–force relation that influences motor performance during isometric, shortening and lengthening muscle contractions and during fatiguing tasks. When examining the effect of eccentric exercise at the single motor unit level, there are substantial changes in recruitment thresholds, discharge rates, motor unit conduction velocities and synchronization, which can last for up to 1 week after eccentric exercise. Examining the time course of these changes suggests that the increased submaximal EMG after eccentric exercise most likely occurs through a decrease in motor unit conduction velocity and an increase in motor unit activity related to antagonist muscle coactivation and low-frequency fatigue. Furthermore, there is a commonly held view that eccentric exercise produces preferential damage to high-threshold motor units, but the evidence for this in humans is limited. Further research is needed to establish whether there is preferential damage to high-threshold motor units after eccentric exercise in humans, preferably by linking changes in motor unit activity with estimates of motor unit size using selective intramuscular recording techniques.

Prostatic urethra malformation associated with retrograde ejaculation: a case report.

Science.gov (United States)

Zhao, Kai; Zhang, Jianzhong; Xu, Aiming; Zhang, Cheng; Wang, Zengjun

2016-12-21

Retrograde ejaculation can have anatomical, neurogenic, or pharmacological causes. Among these factors, malformation of the prostatic urethra is an uncommon cause. We describe a 29-year-old Han Chinese man with absence of his verumontanum combined with ejaculatory duct cysts, and no other cause for ejaculatory dysfunction. His verumontanum was replaced by a deep groove adjacent to his bladder neck, which could significantly influence bladder neck contraction. In addition, the large cysts in the ejaculatory duct could obstruct the anterior outlet of his prostatic urethra and prevent seminal fluid flow in an anterograde direction. There are few reports of retrograde ejaculation associated with congenital malformations of the posterior urethra. Malformations associated with bladder neck laxity and increased tone of the prostatic urethral outlet can contribute to retrograde ejaculation. Malformation of the prostatic urethra is an uncommon cause of retrograde ejaculation, and can be difficult to treat.

Retrograde Melting and Internal Liquid Gettering in Silicon

Energy Technology Data Exchange (ETDEWEB)

Hudelson, Steve; Newman, Bonna K.; Bernardis, Sarah; Fenning, David P.; Bertoni, Mariana I.; Marcus, Matthew A.; Fakra, Sirine C.; Lai, Barry; Buonassisi, Tonio

2011-07-01

Retrograde melting (melting upon cooling) is observed in silicon doped with 3d transition metals, via synchrotron-based temperature-dependent X-ray microprobe measurements. Liquid metal-silicon droplets formed via retrograde melting act as efficient sinks for metal impurities dissolved within the silicon matrix. Cooling results in decomposition of the homogeneous liquid phase into solid multiple-metal alloy precipitates. These phenomena represent a novel pathway for engineering impurities in semiconductor-based systems.

Normative values of eccentric hip abduction strength in novice runners

DEFF Research Database (Denmark)

Jørgensen, Daniel Ramskov; Pedersen, Mette Broen; Kastrup, Kristrian

2014-01-01

.354) Nm/kg. CONCLUSION: Normative values for maximal eccentric hip abduction strength in novice runners can be calculated by taking into account the differences in strength across genders and the decline in strength that occurs with increasing age. Age and gender were associated with maximal eccentric hip...... associated with maximal eccentric hip abduction strength from a univariate analysis were included in a multivariate linear regression model. Based on the results from the regression model, a regression equation for normative hip abduction strength is presented. RESULTS: A SIGNIFICANT DIFFERENCE IN MAXIMAL...... was found, p gender. Based on this, the equation to calculate normative values for relative eccentric hip abduction strength became: (1.600 + (age * -0.005) + (gender (1 = male / 0 = female) * 0.215) ± 1 or 2 * 0...

Dynein is the motor for retrograde axonal transport of organelles

International Nuclear Information System (INIS)

Schnapp, B.J.; Reese, T.S.

1989-01-01

Vesicular organelles in axons of nerve cells are transported along microtubules either toward their plus ends (fast anterograde transport) or toward their minus ends (retrograde transport). Two microtubule-based motors were previously identified by examining plastic beads induced to move along microtubules by cytosol fractions from the squid giant axon: (i) an anterograde motor, kinesin, and (ii) a retrograde motor, which is characterized here. The retrograde motor, a cytosolic protein previously termed HMW1, was purified from optic lobes and extruded axoplasm by nucleotide-dependent microtubule affinity and release; microtubule gliding was used as the assay of motor activity. The following properties of the retrograde motor suggest that it is cytoplasmic dynein: (i) sedimentation at 20-22 S with a heavy chain of Mr greater than 200,000 that coelectrophoreses with the alpha and beta subunits of axonemal dynein, (ii) cleavage by UV irradiation in the presence of ATP and vanadate, and (iii) a molecular structure resembling two-headed dynein from axonemes. Furthermore, bead movement toward the minus end of microtubules was blocked when axoplasmic supernatants were treated with UV/vanadate. Treatment of axoplasmic supernatant with UV/vanadate also blocks the retrograde movement of purified organelles in vitro without changing the number of anterograde moving organelles, indicating that dynein interacts specifically with a subgroup of organelles programmed to move toward the cell body. However, purified optic lobe dynein, like purified kinesin, does not by itself promote the movement of purified organelles along microtubules, suggesting that additional axoplasmic factors are necessary for retrograde as well as anterograde transport

Analysis and optimization of dynamic model of eccentric shaft grinder

Science.gov (United States)

Gao, Yangjie; Han, Qiushi; Li, Qiguang; Peng, Baoying

2018-04-01

Eccentric shaft servo grinder is the core equipment in the process chain of machining eccentric shaft. The establishment of the movement model and the determination of the kinematic relation of the-axis in the grinding process directly affect the quality of the grinding process, and there are many error factors in grinding, and it is very important to analyze the influence of these factors on the work piece quality. The three-dimensional model of eccentric shaft grinder is drawn by Pro/E three-dimensional drawing software, the model is imported into ANSYS Workbench Finite element analysis software, and the finite element analysis is carried out, and then the variation and parameters of each component of the bed are obtained by the modal analysis result. The natural frequencies and formations of the first six steps of the eccentric shaft grinder are obtained by modal analysis, and the weak links of the parts of the grinder are found out, and a reference improvement method is proposed for the design of the eccentric shaft grinder in the future.

Spin-orbital Tidal Dynamics and Tidal Heating in the TRAPPIST-1 Multiplanet System

Science.gov (United States)

Makarov, Valeri V.; Berghea, Ciprian T.; Efroimsky, Michael

2018-04-01

We perform numerical simulations of the TRAPPIST-1 system of seven exoplanets orbiting a nearby M dwarf, starting with a previously suggested stable configuration. The long-term stability of this configuration is confirmed, but the motion of planets is found to be chaotic. The eccentricity values are found to vary within finite ranges. The rates of tidal dissipation and tidal evolution of orbits are estimated, assuming an Earth-like rheology for the planets. We find that under this assumption, the planets b, d, and e were captured in the 3:2 or higher spin–orbit resonances during the initial spin-down, but slipped further down into the 1:1 resonance. Depending on its rheology, the innermost planet b may be captured in a stable pseudosynchronous rotation. Nonsynchronous rotation ensures higher levels of tidal dissipation and internal heating. The positive feedback between the viscosity and the dissipation rate—and the ensuing runaway heating—are terminated by a few self-regulation processes. When the temperature is high and the viscosity is low enough, the planet spontaneously leaves the 3:2 resonance. Further heating is stopped either by passing the peak dissipation or by the emergence of partial melt in the mantle. In the post-solidus state, the tidal dissipation is limited to the levels supported by the heat transfer efficiency. The tides on the host star are unlikely to have had a significant dynamical impact. The tides on the synchronized inner planets tend to reduce these planets’ orbital eccentricity, possibly contributing thereby to the system’s stability.

Using Kinesthetic Activities to Teach Ptolemaic and Copernican Retrograde Motion

Science.gov (United States)

Richards, Ted

2012-06-01

This paper describes a method for teaching planetary retrograde motion, and the Ptolemaic and Copernican accounts of retrograde motion, by means of a series kinesthetic learning activities (KLAs). In the KLAs described, the students literally walk through the motions of the planets in both systems. A retrospective statistical analysis shows that students who participated in these activities performed better on examination questions pertaining to retrograde motion than students who did not. Potential explanations for this result, including the breaking of classroom routine, the effect of body movement on conceptual memory, and egocentric spatial proprioception, are considered.

Innocent Bystanders: Orbital Dynamics of Exomoons During Planet–Planet Scattering

Science.gov (United States)

Hong, Yu-Cian; Raymond, Sean N.; Nicholson, Philip D.; Lunine, Jonathan I.

2018-01-01

Planet–planet scattering is the leading mechanism to explain the broad eccentricity distribution of observed giant exoplanets. Here we study the orbital stability of primordial giant planet moons in this scenario. We use N-body simulations including realistic oblateness and evolving spin evolution for the giant planets. We find that the vast majority (∼80%–90% across all our simulations) of orbital parameter space for moons is destabilized. There is a strong radial dependence, as moons past ∼ 0.1 {R}{Hill} are systematically removed. Closer-in moons on Galilean-moon-like orbits (<0.04 R Hill) have a good (∼20%–40%) chance of survival. Destabilized moons may undergo a collision with the star or a planet, be ejected from the system, be captured by another planet, be ejected but still orbiting its free-floating host planet, or survive on heliocentric orbits as “planets.” The survival rate of moons increases with the host planet mass but is independent of the planet’s final (post-scattering) orbits. Based on our simulations, we predict the existence of an abundant galactic population of free-floating (former) moons.

Assessment of behavior factor of eccentrically braced frame with ...

African Journals Online (AJOL)

Assessment of behavior factor of eccentrically braced frame with vertical link in cyclic loading. ... Journal of Fundamental and Applied Sciences ... In order to understand the behavior of these structures using non-linear static and dynamic analysis of building's behavior factor, eccentric and exocentric systems were calculated ...

Colonic perforation following endoscopic retrograde ...

African Journals Online (AJOL)

We highlight a potentially lethal complication of acute severe pancreatitis that may not be suspected in severely ill patients. A 41-year-old woman developed acute severe pancreatitis following endoscopic retrograde cholangiopancreatography (ERCP) for suspected choledocholithiasis. When her condition deteriorated ...

Muscle damage and repeated bout effect induced by enhanced eccentric squats.

Science.gov (United States)

Coratella, Giuseppe; Chemello, Alessandro; Schena, Federico

2016-12-01

Muscle damage and repeated bout effect have been studied after pure eccentric-only exercise. The aim of this study was to evaluate muscle damage and repeated bout effect induced by enhanced eccentric squat exercise using flywheel device. Thirteen healthy males volunteered for this study. Creatine kinase blood activity (CK), quadriceps isometric peak torque and muscle soreness were used as markers of muscle damage. The dependent parameters were measured at baseline, immediately after and each day up to 96 hours after the exercise session. The intervention consisted of 100 repetitions of enhanced eccentric squat exercise using flywheel device. The same protocol was repeated after 4 weeks. After the first bout, CK and muscle soreness were significantly greater (P0.05), while isometric peak torque and muscle soreness returned to values similar to baseline after respectively 48 and 72 hours. All muscle damage markers were significantly lower after second compared to first bout. The enhanced eccentric exercise induced symptoms of muscle damage up to 96 hours. However, it provided muscle protection after the second bout, performed four weeks later. Although it was not eccentric-only exercise, the enhancement of eccentric phase provided muscle protection.

FRIENDS OF HOT JUPITERS. II. NO CORRESPONDENCE BETWEEN HOT-JUPITER SPIN-ORBIT MISALIGNMENT AND THE INCIDENCE OF DIRECTLY IMAGED STELLAR COMPANIONS

Energy Technology Data Exchange (ETDEWEB)

Ngo, Henry; Knutson, Heather A.; Hinkley, Sasha; Batygin, Konstantin [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA (United States); Crepp, Justin R.; Bechter, Eric B. [Department of Physics, University of Notre Dame, Notre Dame, IN (United States); Howard, Andrew W. [Institute for Astronomy, University of Hawaii at Manoa, Honolulu, HI (United States); Johnson, John A. [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States); Morton, Timothy D. [Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA (United States); Muirhead, Philip S., E-mail: hngo@caltech.edu [Department of Astronomy, Boston University, Boston, MA (United States)

2015-02-20

Multi-star systems are common, yet little is known about a stellar companion's influence on the formation and evolution of planetary systems. For instance, stellar companions may have facilitated the inward migration of hot Jupiters toward to their present day positions. Many observed short-period gas giant planets also have orbits that are misaligned with respect to their star's spin axis, which has also been attributed to the presence of a massive outer companion on a non-coplanar orbit. We present the results of a multi-band direct imaging survey using Keck NIRC2 to measure the fraction of short-period gas giant planets found in multi-star systems. Over three years, we completed a survey of 50 targets ('Friends of Hot Jupiters') with 27 targets showing some signature of multi-body interaction (misaligned or eccentric orbits) and 23 targets in a control sample (well-aligned and circular orbits). We report the masses, projected separations, and confirmed common proper motion for the 19 stellar companions found around 17 stars. Correcting for survey incompleteness, we report companion fractions of 48% ± 9%, 47% ± 12%, and 51% ± 13% in our total, misaligned/eccentric, and control samples, respectively. This total stellar companion fraction is 2.8σ larger than the fraction of field stars with companions approximately 50-2000 AU. We observe no correlation between misaligned/eccentric hot Jupiter systems and the incidence of stellar companions. Combining this result with our previous radial velocity survey, we determine that 72% ± 16% of hot Jupiters are part of multi-planet and/or multi-star systems.

Eccentric Training for Tendon Healing After Acute Lesion: A Rat Model.

Science.gov (United States)

Kaux, Jean-François; Libertiaux, Vincent; Leprince, Pierre; Fillet, Marianne; Denoel, Vincent; Wyss, Clémence; Lecut, Christelle; Gothot, André; Le Goff, Caroline; Croisier, Jean-Louis; Crielaard, Jean-Michel; Drion, Pierre

2017-05-01

The tendon is a dynamic entity that remodels permanently. Platelet-rich plasma (PRP) injection has been shown to have a beneficial effect on tendon healing after lesion in rats. Furthermore, eccentric exercise seems to improve the mechanical quality of the tendon. A combination of PRP injection and eccentric training might be more effective than either treatment alone. Controlled laboratory study. Adult male rats were anesthetized, an incision was performed in the middle of their left patellar tendon and an injection of physiological fluid (PF) or homologous PRP was randomly made at the lesion level. The rats were then divided into 2 groups: the eccentric group, undergoing eccentric training 3 times a week, and the untrained group, without any training. Thus, 4 groups were compared. After 5 weeks, the tendons were removed and their ultimate tensile strength and energy were measured. Tendons were frozen for proteomic analyses when all biomechanical tests were completed. Statistical analysis was performed with linear mixed effect models. No significant difference was found between the treatments using PF injection or PRP injection alone. However, the value of the ultimate tensile force at rupture was increased by 4.5 N (108% of control, P = .006) when eccentric training was performed. An intragroup analysis revealed that eccentric training significantly improved the ultimate force values for the PRP group. Proteomic analysis revealed that eccentric training led to an increase in abundance of several cytoskeletal proteins in the PF group, while a decrease in abundance of enzymes of the glycolytic pathway occurred in the PRP-treated groups, indicating that this treatment might redirect the exercise-driven metabolic plasticity of the tendon. Eccentric training altered the metabolic plasticity of tendon and led to an improvement of injured tendon resistance regardless of the treatment injected (PF or PRP). This study demonstrates the necessity of eccentric rehabilitation

Endoscopic retrograde cholangiopancreatography and endoscopic ...

African Journals Online (AJOL)

An approach to suspected gallstone pancreatitis'based on endoscopic retrograde cholangiopancreatography (ERCP) and endoscopic sphincterotomy (ES) was adopted in 1976 and was followed in 29 patients. ERCp became the routine method of early biliary tract assessment when gallstone pancreatitis was suspected on ...

Importance of variants in cerebrovascular anatomy for potential retrograde embolization in cryptogenic stroke

International Nuclear Information System (INIS)

Markl, Michael; Semaan, Edouard; Carr, James; Collins, Jeremy; Stromberg, LeRoy; Prabhakaran, Shyam

2017-01-01

To test the hypothesis that variants in cerebrovascular anatomy will affect the number of patients demonstrating a plausible retrograde embolization mechanism from plaques in the descending aorta (DAo). Thirty-five patients (aged 63 ± 17 years) with cryptogenic stroke underwent 4D flow MRI for the assessment of aortic 3D blood flow and MR angiography for the evaluation of circle of Willis, posterior circulation, and aortic arch architecture. In patients with proven DAo plaque, retrograde embolization was considered a potential mechanism if retrograde flow extended from the DAo to a supra-aortic vessel supplying the cerebral infarct territory. Retrograde embolization with matching cerebral infarct territory was detected in six (17%) patients. Circle of Willis and aortic arch variant anatomy was found in 60% of patients, leading to reclassification of retrograde embolization risk as present in three (9%) additional patients, for a total 26% of cryptogenic stroke patients. 4D flow MRI demonstrated 26% concordance with infarct location on imaging with retrograde diastolic flow into the feeding vessels of the affected cerebral area, identifying a potential etiology for cryptogenic stroke. Our findings further demonstrate the importance of cerebrovascular anatomy when determining concordance of retrograde flow pathways with vascular stroke territory from DAo plaques. (orig.)

Importance of variants in cerebrovascular anatomy for potential retrograde embolization in cryptogenic stroke

Energy Technology Data Exchange (ETDEWEB)

Markl, Michael [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Northwestern University, Department of Biomedical Engineering, McCormick School of Engineering, Chicago, IL (United States); Semaan, Edouard; Carr, James; Collins, Jeremy [Northwestern University, Department of Radiology, Feinberg School of Medicine, Chicago, IL (United States); Stromberg, LeRoy [Northwestern University, Department of Neurology, Feinberg School of Medicine, Chicago, IL (United States); Edward Hospital, Department of Radiology, Naperville, IL (United States); Prabhakaran, Shyam [Northwestern University, Department of Neurology, Feinberg School of Medicine, Chicago, IL (United States)

2017-10-15

To test the hypothesis that variants in cerebrovascular anatomy will affect the number of patients demonstrating a plausible retrograde embolization mechanism from plaques in the descending aorta (DAo). Thirty-five patients (aged 63 ± 17 years) with cryptogenic stroke underwent 4D flow MRI for the assessment of aortic 3D blood flow and MR angiography for the evaluation of circle of Willis, posterior circulation, and aortic arch architecture. In patients with proven DAo plaque, retrograde embolization was considered a potential mechanism if retrograde flow extended from the DAo to a supra-aortic vessel supplying the cerebral infarct territory. Retrograde embolization with matching cerebral infarct territory was detected in six (17%) patients. Circle of Willis and aortic arch variant anatomy was found in 60% of patients, leading to reclassification of retrograde embolization risk as present in three (9%) additional patients, for a total 26% of cryptogenic stroke patients. 4D flow MRI demonstrated 26% concordance with infarct location on imaging with retrograde diastolic flow into the feeding vessels of the affected cerebral area, identifying a potential etiology for cryptogenic stroke. Our findings further demonstrate the importance of cerebrovascular anatomy when determining concordance of retrograde flow pathways with vascular stroke territory from DAo plaques. (orig.)

Is eccentric exercise an effective treatment for lateral epicondylitis? A systematic review.

Science.gov (United States)

Cullinane, Frances L; Boocock, Mark G; Trevelyan, Fiona C

2014-01-01

To establish the effectiveness of eccentric exercise as a treatment intervention for lateral epicondylitis. ProQuest, Medline via EBSCO, AMED, Scopus, Web of Science, CINAHL. A systematic review was undertaken to identify randomized and controlled clinical trials incorporating eccentric exercise as a treatment for patients diagnosed with lateral epicondylitis. Studies were included if: they incorporated eccentric exercise, either in isolation or as part of a multimodal treatment protocol; they assessed at least one functional or disability outcome measure; and the patients had undergone diagnostic testing. The methodological quality of each study was assessed using the Modified Cochrane Musculoskeletal Injuries Group score sheet. Twelve studies met the inclusion criteria. Three were deemed 'high' quality, seven were 'medium' quality, and two were 'low' quality. Eight of the studies were randomized trials investigating a total of 334 subjects. Following treatment, all groups inclusive of eccentric exercise reported decreased pain and improved function and grip strength from baseline. Seven studies reported improvements in pain, function, and/or grip strength for therapy treatments inclusive of eccentric exercise when compared with those excluding eccentric exercise. Only one low-quality study investigated the isolated effects of eccentric exercise for treating lateral epicondylitis and found no significant improvements in pain when compared with other treatments. The majority of consistent findings support the inclusion of eccentric exercise as part of a multimodal therapy programme for improved outcomes in patients with lateral epicondylitis.

Selective retrograde labeling of cholinergic neurons with [3H]choline

International Nuclear Information System (INIS)

Bagnoli, P.; Beaudet, A.; Stella, M.; Cuenod, M.

1981-01-01

Evidence is presented which is consistent with a specific retrograde labeling of cholinergic neurons following [ 3 H]choline application in their zone of termination. [ 3 H]Choline injection in the rat hippocampus leads to perikaryal retrograde labeling in the ipsilateral medial septal nuclease and nucleus of the diagonal band, thus delineating an established cholinergic pathway, while only diffuse presumably anterograde labeling was observed in the lateral septum, the entorhinal cortex, and the opposite hippocampus. After [ 3 H]choline injection in the pigeon visual Wulst, only the ipsilateral thalamic relay, of all inputs, showed similar perikaryal retrograde labeling, an observation supporting the suggestion that at least some thalamo-Wulst neurons are cholinergic

Searching for gravitational-wave signals emitted by eccentric compact binaries using a non-eccentric template bank: implications for ground-based detectors

Energy Technology Data Exchange (ETDEWEB)

Cokelaer, T; Pathak, D, E-mail: Thomas.Cokelaer@astro.cf.ac.u, E-mail: Devanka.Pathak@astro.cf.ac.u [School of Physics and Astronomy, Cardiff University, Cardiff CF24 3AA (United Kingdom)

2009-02-21

Most of the inspiralling compact binaries are expected to be circularized by the time their gravitational-wave signals enter the frequency band of ground-based detectors such as LIGO or VIRGO. However, it is not excluded that some of these binaries might still possess a significant eccentricity at a few tens of hertz. Despite this possibility, current search pipelines-based on matched filtering techniques-consider only non-eccentric templates. The effect of such an approximation on the loss of signal-to-noise ratio (SNR) has been investigated by Martel and Poisson (1999 Phys. Rev. D 60 124008) in the context of initial LIGO detector. They ascertained that non-eccentric templates will be successful at detecting eccentric signals. We revisit their work by incorporating current and future ground-based detectors and precisely quantify the exact loss of SNR. In order to be more faithful to an actual search, we maximized the SNR over a template bank, whose minimal match is set to 95%. For initial LIGO detector, we claim that the initial eccentricity does not need to be taken into account in our searches for any system with total mass M element of [2-45]M{sub o-dot} if e{sub 0} approx< 0.05 because the loss of SNR (about 5%) is consistent with the discreteness of the template bank. Similarly, this statement is also true for systems with M element of [6-35]M{sub o-dot} and e{sub 0} approx< 0.10. However, by neglecting the eccentricity in our searches, significant loss of detection (larger than 10%) may arise as soon as e{sub 0} >= 0.05 for neutron-star binaries. We also provide exhaustive results for VIRGO, Advanced LIGO and Einstein Telescope detectors. It is worth noting that for Einstein Telescope, neutron star binaries with e{sub 0} >= 0.02 lead to a 10% loss of detection.

Stability of orbits around planetary satellites considering a disturbing body in an elliptical orbit: Applications to Europa and Ganymede

Science.gov (United States)

Cardoso dos Santos, Josué; Carvalho, Jean Paulo; Vilhena de Moraes, Rodolpho

Europa and Ganymede are two of the four Jupiter’s moons which compose the Galilean satellite. These ones are planetary satellites of greater interest at the present moment among the scientific community. There are some missions being planned to visit them and and the Jovian system. One of them is the cooperation between NASA and ESA for the Europa Jupiter System Mission (EJSM). In this mission are planned the insertion of the spacecrafts JEO (Jupiter Europa Orbiter) and JGO (Jupiter Ganymede Orbiter) into Europa and Ganymede’s orbit. Thus, there is a great necessity for having a better comprehension of the dynamics of the orbits around this planetary satellite. This comprehension is essential for the success of this type of mission. In this context, this work aims to perform a search for low-altitude orbits around these planetary satellites. An emphasis is given in polar orbits. These orbits can be useful in the planning of aerospace activities to be conducted around this planetary satellite, with respect to the stability of orbits of artificial satellites. The study considers orbits of an artificial satellite around Europa and Ganymede under the influence of the third-body perturbation (the gravitational attraction of Jupiter) and the polygenic perturbations. These last ones occur due to forces such as the non-uniform distribution of mass (J2 and J3) of the main (central) body. A simplified dynamic model for polygenic perturbations is used. A new model for the third-body disturbance is presented considering it in an elliptical orbit. The Lagrange planetary equations, which compose a system of nonlinear differential equations, are used to describe the orbital motion of the artificial satellite around Ganymede. The equations showed here are developed in closed form to avoid expansions in inclination and eccentricity.

Using Kinesthetic Activities to Teach Ptolemaic and Copernican Retrograde Motion

Science.gov (United States)

Richards, Ted

2012-01-01

This paper describes a method for teaching planetary retrograde motion, and the Ptolemaic and Copernican accounts of retrograde motion, by means of a series kinesthetic learning activities (KLAs). In the KLAs described, the students literally walk through the motions of the planets in both systems. A retrospective statistical analysis shows that…

A Healthy Live Birth Following ICSI with Retrograde Ejaculated Sperm

African Journals Online (AJOL)

AJRH Managing Editor

Retrograde ejaculation, sometimes called dry orgasm, refers to the medical condition when semen enters the urinary bladder. (retrograde) instead of emerging through the penis after orgasm (antegrade). In some instances, a very minute quantity of antegrade semen appears in the ejaculate and may or may not be devoid of ...

DEVIATION OF STELLAR ORBITS FROM TEST PARTICLE TRAJECTORIES AROUND SGr A* DUE TO TIDES AND WINDS

International Nuclear Information System (INIS)

Psaltis, Dimitrios; Li, Gongjie; Loeb, Abraham

2013-01-01

Monitoring the orbits of stars around Sgr A* offers the possibility of detecting the precession of their orbital planes due to frame dragging, of measuring the spin and quadrupole moment of the black hole, and of testing the no-hair theorem. Here we investigate whether the deviations of stellar orbits from test-particle trajectories due to wind mass loss and tidal dissipation of the orbital energy compromise such measurements. We find that the effects of stellar winds are, in general, negligible. On the other hand, for the most eccentric orbits (e > 0.96) for which an optical interferometer, such as GRAVITY, will detect orbital plane precession due to frame dragging, the tidal dissipation of orbital energy occurs at timescales comparable to the timescale of precession due to the quadrupole moment of the black hole. As a result, this non-conservative effect is a potential source of systematic uncertainty in testing the no-hair theorem with stellar orbits

DEVIATION OF STELLAR ORBITS FROM TEST PARTICLE TRAJECTORIES AROUND SGr A* DUE TO TIDES AND WINDS

Energy Technology Data Exchange (ETDEWEB)

Psaltis, Dimitrios [Astronomy Department, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Li, Gongjie; Loeb, Abraham, E-mail: dpsaltis@email.arizona.edu, E-mail: gli@cfa.harvard.edu, E-mail: aloeb@cfa.harvard.edu [Institute for Theory and Computation, Harvard-Smithsonian CfA, 60 Garden Street, Cambridge, MA (United States)

2013-11-01

Monitoring the orbits of stars around Sgr A* offers the possibility of detecting the precession of their orbital planes due to frame dragging, of measuring the spin and quadrupole moment of the black hole, and of testing the no-hair theorem. Here we investigate whether the deviations of stellar orbits from test-particle trajectories due to wind mass loss and tidal dissipation of the orbital energy compromise such measurements. We find that the effects of stellar winds are, in general, negligible. On the other hand, for the most eccentric orbits (e > 0.96) for which an optical interferometer, such as GRAVITY, will detect orbital plane precession due to frame dragging, the tidal dissipation of orbital energy occurs at timescales comparable to the timescale of precession due to the quadrupole moment of the black hole. As a result, this non-conservative effect is a potential source of systematic uncertainty in testing the no-hair theorem with stellar orbits.

The 'SAFARI' Technique Using Retrograde Access Via Peroneal Artery Access

Energy Technology Data Exchange (ETDEWEB)

Zhuang, Kun Da, E-mail: zkunda@gmail.com [Singapore General Hospital, Interventional Radiology Centre (Singapore); Tan, Seck Guan [Singapore General Hospital, Department of General Surgery (Singapore); Tay, Kiang Hiong [Singapore General Hospital, Interventional Radiology Centre (Singapore)

2012-08-15

The 'SAFARI' technique or subintimal arterial flossing with antegrade-retrograde intervention is a method for recanalisation of chronic total occlusions (CTOs) when subintimal angioplasty fails. Retrograde access is usually obtained via the popliteal, distal anterior tibial artery (ATA)/dorsalis pedis (DP), or distal posterior tibial artery (PTA). Distal access via the peroneal artery has not been described and has a risk of continued bleeding, leading to compartment syndrome due to its deep location. We describe our experience in two patients with retrograde access via the peroneal artery and the use of balloon-assisted hemostasis for these retrograde punctures. This approach may potentially give more options for endovascular interventions in lower limb CTOs.

The Eccentric-distance Sum of Some Graphs

OpenAIRE

P, Padmapriya; Mathad, Veena

2017-01-01

Let $G = (V,E)$ be a simple connected graph. Theeccentric-distance sum of $G$ is defined as$\\xi^{ds}(G) =\\ds\\sum_{\\{u,v\\}\\subseteq V(G)} [e(u)+e(v)] d(u,v)$, where $e(u)$ %\\dsis the eccentricity of the vertex $u$ in $G$ and $d(u,v)$ is thedistance between $u$ and $v$. In this paper, we establish formulaeto calculate the eccentric-distance sum for some graphs, namelywheel, star, broom, lollipop, double star, friendship, multi-stargraph and the join of $P_{n-2}$ and $P_2$.

The eccentric-distance sum of some graphs

Directory of Open Access Journals (Sweden)

Padmapriya P

2017-04-01

Full Text Available Let $G = (V,E$ be a simple connected graph. Theeccentric-distance sum of $G$ is defined as$\\xi^{ds}(G =\\ds\\sum_{\\{u,v\\}\\subseteq V(G} [e(u+e(v] d(u,v$, where $e(u$ %\\dsis the eccentricity of the vertex $u$ in $G$ and $d(u,v$ is thedistance between $u$ and $v$. In this paper, we establish formulaeto calculate the eccentric-distance sum for some graphs, namelywheel, star, broom, lollipop, double star, friendship, multi-stargraph and the join of $P_{n-2}$ and $P_2$.

Physiological and Neural Adaptations to Eccentric Exercise: Mechanisms and Considerations for Training

Directory of Open Access Journals (Sweden)

Nosratollah Hedayatpour

2015-01-01

Full Text Available Eccentric exercise is characterized by initial unfavorable effects such as subcellular muscle damage, pain, reduced fiber excitability, and initial muscle weakness. However, stretch combined with overload, as in eccentric contractions, is an effective stimulus for inducing physiological and neural adaptations to training. Eccentric exercise-induced adaptations include muscle hypertrophy, increased cortical activity, and changes in motor unit behavior, all of which contribute to improved muscle function. In this brief review, neuromuscular adaptations to different forms of exercise are reviewed, the positive training effects of eccentric exercise are presented, and the implications for training are considered.

Retrograde amnesia after electroconvulsive therapy: a temporary effect?

Science.gov (United States)

Meeter, Martijn; Murre, Jaap M J; Janssen, Steve M J; Birkenhager, Tom; van den Broek, W W

2011-07-01

Although electroconvulsive therapy (ECT) is generally considered effective against depression, it remains controversial because of its association with retrograde memory loss. Here, we assessed memory after ECT in circumstances most likely to yield strong retrograde amnesia. A cohort of patients undergoing ECT for major depression was tested before and after ECT, and again at 3-months follow-up. Included were 21 patients scheduled to undergo bilateral ECT for severe major depression and 135 controls matched for gender, age, education, and media consumption. Two memory tests were used: a verbal learning test to assess anterograde memory function, and a remote memory test that assessed memory for news during the course of one year. Before ECT the patients' scores were lower than those of controls. They were lower again after treatment, suggesting retrograde amnesia. At follow-up, however, memory for events before treatment had returned to the pre-ECT level. Memory for events in the months after treatment was as good as that of controls. The sample size in this study was not large. Moreover, memory impairment did not correlate with level of depression, which may be due to restriction of range. Our results are consistent with the possibility that ECT as currently practiced does not cause significant lasting retrograde amnesia, but that amnesia is mostly temporary and related to the period of impairment immediately following ECT. Copyright © 2011 Elsevier B.V. All rights reserved.

Eccentric Contraction-Induced Muscle Fibre Adaptation

Directory of Open Access Journals (Sweden)

Arabadzhiev T. I.

2009-12-01

Full Text Available Hard-strength training induces strength increasing and muscle damage, especially after eccentric contractions. Eccentric contractions also lead to muscle adaptation. Symptoms of damage after repeated bout of the same or similar eccentrically biased exercises are markedly reduced. The mechanism of this repeated bout effect is unknown. Since electromyographic (EMG power spectra scale to lower frequencies, the adaptation is related to neural adaptation of the central nervous system (CNS presuming activation of slow-non-fatigable motor units or synchronization of motor unit firing. However, the repeated bout effect is also observed under repeated stimulation, i.e. without participation of the CNS. The aim of this study was to compare the possible effects of changes in intracellular action potential shape and in synchronization of motor units firing on EMG power spectra. To estimate possible degree of the effects of central and peripheral changes, interferent EMG was simulated under different intracellular action potential shapes and different degrees of synchronization of motor unit firing. It was shown that the effect of changes in intracellular action potential shape and muscle fibre propagation velocity (i.e. peripheral factors on spectral characteristics of EMG signals could be stronger than the effect of synchronization of firing of different motor units (i.e. central factors.

STABLE CONIC-HELICAL ORBITS OF PLANETS AROUND BINARY STARS: ANALYTICAL RESULTS

Energy Technology Data Exchange (ETDEWEB)

Oks, E. [Physics Department, 206 Allison Lab., Auburn University, Auburn, AL 36849 (United States)

2015-05-10

Studies of planets in binary star systems are especially important because it was estimated that about half of binary stars are capable of supporting habitable terrestrial planets within stable orbital ranges. One-planet binary star systems (OBSS) have a limited analogy to objects studied in atomic/molecular physics: one-electron Rydberg quasimolecules (ORQ). Specifically, ORQ, consisting of two fully stripped ions of the nuclear charges Z and Z′ plus one highly excited electron, are encountered in various plasmas containing more than one kind of ion. Classical analytical studies of ORQ resulted in the discovery of classical stable electronic orbits with the shape of a helix on the surface of a cone. In the present paper we show that despite several important distinctions between OBSS and ORQ, it is possible for OBSS to have stable planetary orbits in the shape of a helix on a conical surface, whose axis of symmetry coincides with the interstellar axis; the stability is not affected by the rotation of the stars. Further, we demonstrate that the eccentricity of the stars’ orbits does not affect the stability of the helical planetary motion if the center of symmetry of the helix is relatively close to the star of the larger mass. We also show that if the center of symmetry of the conic-helical planetary orbit is relatively close to the star of the smaller mass, a sufficiently large eccentricity of stars’ orbits can switch the planetary motion to the unstable mode and the planet would escape the system. We demonstrate that such planets are transitable for the overwhelming majority of inclinations of plane of the stars’ orbits (i.e., the projections of the planet and the adjacent start on the plane of the sky coincide once in a while). This means that conic-helical planetary orbits at binary stars can be detected photometrically. We consider, as an example, Kepler-16 binary stars to provide illustrative numerical data on the possible parameters and the

Densities and eccentricities of 139 Kepler planets from transit time variations

Energy Technology Data Exchange (ETDEWEB)

Hadden, Sam; Lithwick, Yoram [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States)

2014-05-20

We extract densities and eccentricities of 139 sub-Jovian planets by analyzing transit time variations (TTVs) obtained by the Kepler mission through Quarter 12. We partially circumvent the degeneracies that plague TTV inversion with the help of an analytical formula for the TTV. From the observed TTV phases, we find that most of these planets have eccentricities of the order of a few percent. More precisely, the rms eccentricity is 0.018{sub −0.004}{sup +0.005}, and planets smaller than 2.5 R {sub ⊕} are around twice as eccentric as those bigger than 2.5 R {sub ⊕}. We also find a best-fit density-radius relationship ρ ≈ 3 g cm{sup –3} × (R/3 R {sub ⊕}){sup –2.3} for the 56 planets that likely have small eccentricity and hence small statistical correction to their masses. Many planets larger than 2.5 R {sub ⊕} are less dense than water, implying that their radii are largely set by a massive hydrogen atmosphere.

Genealogy and stability of periodic orbit families around uniformly rotating asteroids

Science.gov (United States)

Hou, Xiyun; Xin, Xiaosheng; Feng, Jinglang

2018-03-01

Resonance orbits around a uniformly rotating asteroid are studied from the approach of periodic orbits in this work. Three periodic families (denoted as I, II, and III in the paper) are fundamental in organizing the resonance families. For the planar case: (1) Genealogy and stability of Families I, II and the prograde resonance families are studied. For extremely irregular asteroids, family genealogy close to the asteroid is greatly distorted from that of the two body-problem (2BP), indicating that it is inappropriate to treat the orbital motions as perturbed Keplerian orbits. (2) Genealogy and stability of Family III are also studied. Stability of this family may be destroyed by the secular resonance between the orbital ascending node's precession and the asteroid's rotation. For the spatial case: (1) Genealogy of the near circular three-dimensional periodic families are studied. The genealogy may be broken apart by families of eccentric frozen orbits whose argument of perigee is ;frozen; in space. (2) The joint effects between the secular resonance and the orbital resonances may cause instability to three-dimensional orbital motion with orbit inclinations close to the critical values. Applying the general methodology to a case study - the asteroid Eros and also considering higher order non-spherical terms, some extraordinary orbits are found, such as the ones with orbital plane co-rotating with the asteroid, and the stable frozen orbits with argument of perigee librating around values different from 0°, 90°, 180°, 270°.

Optimal Timing for Laparoscopic Cholecystectomy After Endoscopic Retrograde Cholangiopancreatography: A Systematic Review.

Science.gov (United States)

Friis, C; Rothman, J P; Burcharth, J; Rosenberg, J

2018-06-01

Endoscopic retrograde cholangiopancreatography followed by laparoscopic cholecystectomy is often used as definitive treatment for common bile duct stones. The aim of this study was to investigate the optimal time interval between endoscopic retrograde cholangiopancreatography and laparoscopic cholecystectomy. PubMed and Embase were searched for studies comparing different time delays between endoscopic retrograde cholangiopancreatography and laparoscopic cholecystectomy. Observational studies and randomized controlled trials were included. Primary outcome was conversion rate from laparoscopic to open cholecystectomy and secondary outcomes were complications, mortality, operating time, and length of stay. A total of 14 studies with a total of 1930 patients were included. The pooled estimate revealed an increase from a 4.2% conversion rate when laparoscopic cholecystectomy was performed within 24 h of endoscopic retrograde cholangiopancreatography to 7.6% for 24-72 h delay to 12.3% when performed within 2 weeks, to 12.3% for 2-6 weeks, and to a 14% conversion rate when operation was delayed more than 6 weeks. According to this systematic review, it is preferable to perform cholecystectomy within 24 h of endoscopic retrograde cholangiopancreatography to reduce conversion rate. Early laparoscopic cholecystectomy does not increase mortality, perioperative complications, or length of stay and on the contrary it reduces the risk of reoccurrence and progression of disease in the delay between endoscopic retrograde cholangiopancreatography and laparoscopic cholecystectomy.

Post-Golgi anterograde transport requires GARP-dependent endosome-to-TGN retrograde transport

Science.gov (United States)

Hirata, Tetsuya; Fujita, Morihisa; Nakamura, Shota; Gotoh, Kazuyoshi; Motooka, Daisuke; Murakami, Yoshiko; Maeda, Yusuke; Kinoshita, Taroh

2015-01-01

The importance of endosome-to–trans-Golgi network (TGN) retrograde transport in the anterograde transport of proteins is unclear. In this study, genome-wide screening of the factors necessary for efficient anterograde protein transport in human haploid cells identified subunits of the Golgi-associated retrograde protein (GARP) complex, a tethering factor involved in endosome-to-TGN transport. Knockout (KO) of each of the four GARP subunits, VPS51–VPS54, in HEK293 cells caused severely defective anterograde transport of both glycosylphosphatidylinositol (GPI)-anchored and transmembrane proteins from the TGN. Overexpression of VAMP4, v-SNARE, in VPS54-KO cells partially restored not only endosome-to-TGN retrograde transport, but also anterograde transport of both GPI-anchored and transmembrane proteins. Further screening for genes whose overexpression normalized the VPS54-KO phenotype identified TMEM87A, encoding an uncharacterized Golgi-resident membrane protein. Overexpression of TMEM87A or its close homologue TMEM87B in VPS54-KO cells partially restored endosome-to-TGN retrograde transport and anterograde transport. Therefore GARP- and VAMP4-dependent endosome-to-TGN retrograde transport is required for recycling of molecules critical for efficient post-Golgi anterograde transport of cell-surface integral membrane proteins. In addition, TMEM87A and TMEM87B are involved in endosome-to-TGN retrograde transport. PMID:26157166

Optimisation of the Future Routine Orbit for Mars Express

Science.gov (United States)

Carranza, Manuel; Companys, Vincente

2007-01-01

Mars Express (MEX), the first planetary mission of the European Space Agency (ESA), reached Mars on December 25th 2003. Since then it is performing routine operations. Its operational phase had to cover one Martian year, with the possibility of an extension for a second Martian year (i.e. until November 2007). The end of the mission extension is approaching but, given the good health of the payload instruments and the high science return of the mission, there is a strong will to achieve further extensions. Mars Express is also seen as an important asset, capable to provide relay functions for future Martian missions. The ESA Science Program Committee has recently approved a second extension of the MEX mission until May 2009 and even further extensions are possible. Mars Express has an eccentric quasi-polar orbit with a period of approximately 6.72 hours and a pericentre height of about 300 km. Science observations are mainly performed at pericentre (but not only). In addition the orbit has a resonance of 11 revolutions per 3 Martian days. This means that ground tracks corresponding to orbits separated by 11 revolutions are adjacent, such that a given area can be covered by the on-board camera without leaving gaps. The J2 effect of Mars causes a drift of both ascending node and argument of pericentre. The drift of argument of pericentre makes it possible to observe periodically all Mars latitudes from close distance. Illumination conditions at pericentre are influenced by both the drift of the argument of pericentre and the drift of ascending node, as well as by the rotation of Mars around the Sun. The original MEX routine orbit was optimized for the duration of the nominal mission and extension, such that it produced a balanced share of day-side observations (for the optical instruments) and night-side observations (for the radar). The orbit was thus not optimized for the time beyond the assumed extension. Indeed, the evolution of the ascending node and argument of

Retrograde contrast radiography of the distal portions of the intestinal tract in foals

International Nuclear Information System (INIS)

Fischer, A.T.; Yarbrough, T.Y.

1995-01-01

A technique for retrograde contrast radiography of the distal portions of the intestinal tract of foals was developed and then performed in 25 foals (1 to 30 days old) with colic. Retrograde contrast radiography was shown to be sensitive (100%) and specific (100%) for evaluating obstruction of the small colon or transverse colon. It was slightly less sensitive (86%) and specific (83%) for evaluation of the entire large colon, particularly in older foals. Retrograde contrast radiography provided increased diagnostic capability, compared with that for noncontrast radiography. Retrograde contrast radiography can provide valuable information when evaluating foals with colic and should be part of the diagnostic evaluation

Effect of eccentric training on the plantar flexor muscle-tendon tissue properties.

Science.gov (United States)

Mahieu, Nele Nathalie; McNair, Peter; Cools, Ann; D'Haen, Caroline; Vandermeulen, Katrien; Witvrouw, Erik

2008-01-01

It has been shown that eccentric training can be effective in the rehabilitation of patients with Achilles tendonopathy. The mechanism behind these results is not clear. However, there is evidence that tendons are able to respond to repeated forces by altering their structure and composition, and, thus, their mechanical properties change. In this regard, the objective of the present study was to investigate whether eccentric training affects the mechanical properties of the plantar flexor's muscle-tendon tissue properties. Seventy-four healthy subjects were randomized into two groups: an eccentric training group and a control group. The eccentric training group performed a 6-wk eccentric training program for the calf muscles. Before and after this period, all subjects were evaluated for dorsiflexion range of motion using universal goniometry, passive resistive torque of the plantar flexors, and stiffness of the Achilles tendon. Passive resistive torque was measured during ankle dorsiflexion on an isokinetic dynamometer. Stiffness of the Achilles tendon was assessed using a dynamometer, in combination with ultrasonography. The results of the study reveal that the dorsiflexion range of motion was significantly increased only in the eccentric training group. The eccentric heel drop program also resulted in a significant decrease of the passive resistive torque of the plantar flexors (from 16.423 +/- 0.827 to 12.651 +/- 0.617 N.m). The stiffness of the Achilles tendon did not change significantly as a result of training. These findings provide evidence that an eccentric training program results in changes to some of the mechanical properties of the plantar flexor muscles. These changes were thought to be associated with modifications to structure rather than to stretch tolerance.

A novel fluorescent retrograde neural tracer: cholera toxin B conjugated carbon dots

Science.gov (United States)

Zhou, Nan; Hao, Zeyu; Zhao, Xiaohuan; Maharjan, Suraj; Zhu, Shoujun; Song, Yubin; Yang, Bai; Lu, Laijin

2015-09-01

The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde tracers.The retrograde neuroanatomical tracing method is a key technique to study the complex interconnections of the nervous system. Traditional tracers have several drawbacks, including time-consuming immunohistochemical or immunofluorescent staining procedures, rapid fluorescence quenching and low fluorescence intensity. Carbon dots (CDs) have been widely used as a fluorescent bio-probe due to their ultrasmall size, excellent optical properties, chemical stability, biocompatibility and low toxicity. Herein, we develop a novel fluorescent neural tracer: cholera toxin B-carbon dot conjugates (CTB-CDs). It can be taken up and retrogradely transported by neurons in the peripheral nervous system of rats. Our results show that CTB-CDs possess high photoluminescence intensity, good optical stability, a long shelf-life and non-toxicity. Tracing with CTB-CDs is a direct and more economical way of performing retrograde labelling experiments. Therefore, CTB-CDs are reliable fluorescent retrograde

Two-Body Orbit Expansion Due to Time-Dependent Relative Acceleration Rate of the Cosmological Scale Factor

Directory of Open Access Journals (Sweden)

Lorenzo Iorio

2014-01-01

Full Text Available By phenomenologically assuming a slow temporal variation of the percent acceleration rate S̈S -1 of the cosmic scale factor S(t, it is shown that the orbit of a local binary undergoes a secular expansion. To first order in the power expansion of S̈S -1 around the present epoch t0, a non-vanishing shift per orbit (Δr of the two-body relative distance r occurs for eccentric trajectories. A general relativistic expression, which turns out to be cubic in the Hubble parameter H0 at the present epoch, is explicitly calculated for it in the case of matter-dominated epochs with Dark Energy. For a highly eccentric Oort comet orbit with period Pb ≈ 31 Myr, the general relativistic distance shift per orbit turns out to be of the order of (Δr ≈ 70 km. For the Large Magellanic Cloud, assumed on a bound elliptic orbit around the Milky Way, the shift per orbit is of the order of (Δr ≈ 2–4 pc. Our result has a general validity since it holds in any cosmological model admitting the Hubble law and a slowly varying S̈S-1(t. More generally, it is valid for an arbitrary Hooke-like extra-acceleration whose “elastic” parameter κ is slowly time-dependent, irrespectively of the physical mechanism which may lead to it. The coefficient κ1 of the first-order term of the power expansion of κ(t can be preliminarily constrained in a model-independent way down to a κ1 ≲ 2 x 10-13 year-3 level from latest Solar System’s planetary observations. The radial velocities of the double lined spectroscopic binary ALPHA Cen AB yield κ1 ≲ 10-8 year-3.

Eccentric bracing of steel frames in seismic design

International Nuclear Information System (INIS)

Popov, E.P.; Manheim, D.

1981-01-01

The general concepts of designing eccentrically braced steel frames are discussed. A number of possible bracing configurations are pointed out which are suitable for this type of framing. The necessity for considering the collapse mechanism for the selected frame is brought out, and the need for considering the ductility demands for the critical elements is indicated. The need for web stiffness along the critical beam elements (links), and the necessity for lateral bracing at the potential plastic hinges is emphasized. Properly designed eccentrically braced frames provide good drift control for moderate earthquakes, and good ductility for extreme earthquakes. Experience gained in practice attests to the practicality and economy of this kind of framing. The major disadvantage of properly designed eccentrically braced frames lies in the fact that high local distortions may occur during a severe earthquake requiring repair. However, such severe distortions should attenuate rapidly from the damaged areas. (orig./HP)

Change of Direction Speed: Toward a Strength Training Approach with Accentuated Eccentric Muscle Actions.

Science.gov (United States)

Chaabene, Helmi; Prieske, Olaf; Negra, Yassine; Granacher, Urs

2018-03-28

There is growing evidence that eccentric strength training appears to have benefits over traditional strength training (i.e., strength training with combined concentric and eccentric muscle actions) from muscular, neuromuscular, tendinous, and metabolic perspectives. Eccentric muscle strength is particularly needed to decelerate and stabilize the body during the braking phase of a jump exercise or during rapid changes of direction (CoD) tasks. However, surprisingly little research has been conducted to elucidate the effects of eccentric strength training or strength training with accentuated eccentric muscle actions on CoD speed performance. In this current opinion article, we present findings from cross-sectional studies on the relationship between measures of eccentric muscle strength and CoD speed performance. In addition, we summarize the few available studies on the effects of strength training with accentuated eccentric muscle actions on CoD speed performance in athletic populations. Finally, we propose strength training with accentuated eccentric muscle actions as a promising element in strength and conditioning programs of sports with high CoD speed demands. Our findings from five cross-sectional studies revealed statistically significant moderate- to large-sized correlations (r = 0.45-0.89) between measures of eccentric muscle strength and CoD speed performance in athletic populations. The identified three intervention studies were of limited methodological quality and reported small- to large-sized effects (d = 0.46-1.31) of strength training with accentuated eccentric muscle actions on CoD speed performance in athletes. With reference to the available but preliminary literature and from a performance-related point of view, we recommend strength and conditioning coaches to include strength training with accentuated eccentric muscle actions in training routines of sports with high CoD speed demands (e.g., soccer, handball, basketball, hockey) to

Eccentric exercise training in patients with chronic obstructive pulmonary disease.

NARCIS (Netherlands)

Rooyackers, J.M.; Berkeljon, D.A.; Folgering, H.T.M.

2003-01-01

The oxygen cost of eccentric exercise is lower than that of concentric exercise at similar work-loads. In this study, the response to eccentric cycle exercise training (EET) in addition to general exercise training (GET) on exercise performance and quality of life was investigated in 24 patients

The effect of wheel eccentricity and run-out on grinding forces, waviness, wheel wear and chatter

OpenAIRE

O'DONNELL, GARRET; MURPHY, STUART

2011-01-01

PUBLISHED The effect of grinding-wheel eccentricity on grinding forces, wheel wear and final waviness height was studied. Eccentricity was evident in force oscillations and acceleration and audio measurements. A model was developed to predict final scallop-profile shape from grinding parameters and eccentricity. Recommendations are given on detecting eccentricity and determining when eccentricity is tolerable.

The Yeast Retrograde Response as a Model of Intracellular Signaling of Mitochondrial Dysfunction

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S. Michal eJazwinski

2012-05-01

Full Text Available Mitochondrial dysfunction activates intracellular signaling pathways that impact yeast longevity, and the best known of these pathways is the retrograde response. More recently, similar responses have been discerned in other systems, from invertebrates to human cells. However, the identity of the signal transducers is either unknown or apparently diverse, contrasting with the well-established signaling module of the yeast retrograde response. On the other hand, it has become equally clear that several other pathways and processes interact with the retrograde response, embedding it in a network responsive to a variety of cellular states. An examination of this network supports the notion that the master regulator NFkB aggregated a variety of mitochondria-related cellular responses at some point in evolution and has become the retrograde transcription factor. This has significant consequences for how we view some of the deficits associated with aging, such as inflammation. The support for NFkB as the retrograde response transcription factor is not only based on functional analyses. It is bolstered by the fact that NFkB can regulate Myc-Max, which is activated in human cells with dysfunctional mitochondria and impacts cellular metabolism. Myc-Max is homologous to the yeast retrograde response transcription factor Rtg1-Rtg3. Further research will be needed to disentangle the pro-aging from the anti-aging effects of NFkB. Interestingly, this is also a challenge for the complete understanding of the yeast retrograde response.

Effects of inulin with different degree of polymerization on gelatinization and retrogradation of wheat starch.

Science.gov (United States)

Luo, Denglin; Li, Yun; Xu, Baocheng; Ren, Guangyue; Li, Peiyan; Li, Xuan; Han, Sihai; Liu, Jianxue

2017-08-15

The effects of three types of inulin, including FS (DP≤10), FI (DP of 2-60) and FXL (DP≥23), on the gelatinization and retrogradation characteristics of wheat starch were investigated. As the concentration of inulin added into starch increased, the gelatinization temperature increased whereas the breakdown value decreased, and the value of setback first decreased and then increased slightly. The three types of inulin with lower concentrations (inulin showed a significant suppression of starch retrogradation in the addition range of 5-7.5%. They can all inhibit amylose retrogradation, but accelerate amylopectin retrogradation. Inulin with lower DP has stronger effects on the starch retrogradation. Generally, the three types of inulin can all retard the retrogradation performance of wheat starch to some extent in the long-term storage. Copyright © 2017 Elsevier Ltd. All rights reserved.

THE GRAVITATIONAL INTERACTION BETWEEN PLANETS ON INCLINED ORBITS AND PROTOPLANETARY DISKS AS THE ORIGIN OF PRIMORDIAL SPIN–ORBIT MISALIGNMENTS

Energy Technology Data Exchange (ETDEWEB)

Matsakos, Titos; Königl, Arieh [Department of Astronomy and Astrophysics and The Enrico Fermi Institute, The University of Chicago, Chicago, IL 60637 (United States)

2017-02-01

Many of the observed spin–orbit alignment properties of exoplanets can be explained in the context of the primordial disk misalignment model, in which an initially aligned protoplanetary disk is torqued by a distant stellar companion on a misaligned orbit, resulting in a precessional motion that can lead to large-amplitude oscillations of the spin–orbit angle. We consider a variant of this model in which the companion is a giant planet with an orbital radius of a few astronomical units. Guided by the results of published numerical simulations, we model the dynamical evolution of this system by dividing the disk into inner and outer parts—separated at the location of the planet—that behave as distinct, rigid disks. We show that the planet misaligns the inner disk even as the orientation of the outer disk remains unchanged. In addition to the oscillations induced by the precessional motion, whose amplitude is larger the smaller the initial inner-disk-to-planet mass ratio, the spin–orbit angle also exhibits a secular growth in this case—driven by ongoing mass depletion from the disk—that becomes significant when the inner disk’s angular momentum drops below that of the planet. Altogether, these two effects can produce significant misalignment angles for the inner disk, including retrograde configurations. We discuss these results within the framework of the Stranded Hot Jupiter scenario and consider their implications, including the interpretation of the alignment properties of debris disks.

Transneuronal retrograde dual viral labelling of central autonomic circuitry : possibilities and pitfalls

NARCIS (Netherlands)

Ter Horst, GJ

2000-01-01

Viral retrograde transneuronal labelling has become an important neuroanatomical tract-tracing tool for characterization of Limbic neuronal networks. Recently, dual viral retrograde transneuronal labelling has been introduced; a method employing differential transgene expression of two genetically

Retrograde or antegrade double-pigtail stent placement for malignant ureteric obstruction?

International Nuclear Information System (INIS)

Uthappa, M.C.; Cowan, N.C.

2005-01-01

AIM: To determine the optimum approach for double-pigtail stent placement in malignant ureteric obstruction. PATIENTS AND METHODS: Retrograde stent placement was attempted in a consecutive series of patients presenting with malignant ureteric obstruction. If retrograde stent placement was unsuccessful, percutaneous nephrostomy was performed immediately followed by elective antegrade stent placement. Identical digital C-arm fluoroscopy for image-guidance and conditions for anaesthesia and analgesia were employed for both retrograde and antegrade procedures. Identical 8 Fr (20-26 cm) double-pigtail hydrophilic coated stents were used for each approach. RESULTS: Retrograde placement was attempted in 50 ureters in 30 patients {19 male, 11 female, average age 61.4 yr (range 29-90 yr)} over a 24-month period. The success rate for retrograde ureteric stent placement was 50% (n=25/50). Technical failures were due to failure to identify the ureteric orifice (n=22), failure to cross the stricture (n=1), failure to pass the stent (n=1) and failure to pass a 4 Fr catheter (n=1). Antegrade placement was attempted in 25 ureters with a success rate of 96% (n=24/25). Failure in the one case was due to inability to cross an upper third stricture secondary to pyeloureteritis cystica. CONCLUSION: It is suggested that retrograde route should be the initial approach if imaging shows no involvement of ureteric orifice (UO), when nephrostomy is technically very difficult or in cases of solitary kidney. The antegrade route is preferred if imaging shows tumour occlusion of the UO or if there is a tight stricture very close to the uretero-vesical junction (UVJ) making purchase within the ureter difficult for crossing the stricture

Effects of low molecular sugars on the retrogradation of tapioca starch gels during storage.

Directory of Open Access Journals (Sweden)

Xiaoyu Zhang

Full Text Available The effects of low molecular sugars (sucrose, glucose and trehalose on the retrogradation of tapioca starch (TS gels stored at 4°C for different periods were examined with different methods. Decrease in melting enthalpy (ΔHmelt were obtained through differential scanning calorimetry analysis. Analysis of decrease in crystallization rate constant (k and increase in semi-crystallization time (τ1/2 results obtained from retrogradation kinetics indicated that low molecular sugars could retard the retrogradation of TS gels and further revealed trehalose as the best inhibitor among the sugars used in this study. Fourier transform infrared (FTIR analysis indicated that the intensity ratio of 1047 to 1022 cm-1 was increased with the addition of sugars in the order of trehalose > sucrose > glucose. Decrease in hardness parameters and increase in springiness parameters obtained from texture profile analysis (TPA analysis also indicated that low molecular sugars could retard the retrogradation of TS gels. The results of FTIR and TPA showed a consistent sugar effect on starch retrogradation with those of DSC and retrogradation kinetics analysis.

Complications of bladder distension during retrograde urethrography.

Science.gov (United States)

Barsanti, J A; Crowell, W; Losonsky, J; Talkington, F D

1981-05-01

A severe, ulcerative cystitis that resulted in macroscopic hematuria occurred in 8 of 20 healthy dogs undergoing a series of diagnostic tests. Four of the remaining 12 dogs had mild bladder lesions consisting of submucosal edema and hemorrhage. Nine of the 20 dogs developed urinary tract infection after the procedures. These complications seemed associated with the radiographic technique of retrograde urethrography performed when the urinary bladder was distended. To test this hypothesis, retrograde urethrography was performed on 5 additional dogs. With the bladder undistended, no complications occurred. However, distention of these same dogs' bladders for 1 minute or less with sterile lactated Ringer's solution administered through a Foley catheter in the penile urethra resulted in a macroscopic hematuria in all 5 dogs which persisted for 24 hours. A microscopic hematuria continued for 5 days. One dog developed a bacterial urinary tract infection. A severe fibrinopurulent cystitis was present at necropsy of 2 dogs 2 days after distention. The morphologic changes in the bladder gradually diminished over 7 days, but mild submucosal edema and hemorrhage were still present when 2 dogs were necropsied, 7 days after distention. These studies indicated that retrograde urethrography in dogs may be complicated by hemorrhagic cystitis and urinary tract infection if performed with urinary bladder distention.

Eccentric training as a new approach for rotator cuff tendinopathy: Review and perspectives

Science.gov (United States)

Camargo, Paula R; Alburquerque-Sendín, Francisco; Salvini, Tania F

2014-01-01

Excessive mechanical loading is considered the major cause of rotator cuff tendinopathy. Although tendon problems are very common, they are not always easy to treat. Eccentric training has been proposed as an effective conservative treatment for the Achilles and patellar tendinopathies, but less evidence exists about its effectiveness for the rotator cuff tendinopathy. The mechanotransduction process associated with an adequate dose of mechanical load might explain the beneficial results of applying the eccentric training to the tendons. An adequate load increases healing and an inadequate (over or underuse) load can deteriorate the tendon structure. Different eccentric training protocols have been used in the few studies conducted for people with rotator cuff tendinopathy. Further, the effects of the eccentric training for rotator cuff tendinopathy were only evaluated on pain, function and strength. Future studies should assess the effects of the eccentric training also on shoulder kinematics and muscle activity. Individualization of the exercise prescription, comprehension and motivation of the patients, and the establishment of specific goals, practice and efforts should all be considered when prescribing the eccentric training. In conclusion, eccentric training should be used aiming improvement of the tendon degeneration, but more evidence is necessary to establish the adequate dose-response and to determine long-term follow-up effects. PMID:25405092

Geometrical theory to predict eccentric photorefraction intensity profiles in the human eye

Science.gov (United States)

Roorda, Austin; Campbell, Melanie C. W.; Bobier, W. R.

1995-08-01

In eccentric photorefraction, light returning from the retina of the eye is photographed by a camera focused on the eye's pupil. We use a geometrical model of eccentric photorefraction to generate intensity profiles across the pupil image. The intensity profiles for three different monochromatic aberration functions induced in a single eye are predicted and show good agreement with the measured eccentric photorefraction intensity profiles. A directional reflection from the retina is incorporated into the calculation. Intensity profiles for symmetric and asymmetric aberrations are generated and measured. The latter profile shows a dependency on the source position and the meridian. The magnitude of the effect of thresholding on measured pattern extents is predicted. Monochromatic aberrations in human eyes will cause deviations in the eccentric photorefraction measurements from traditional crescents caused by defocus and may cause misdiagnoses of ametropia or anisometropia. Our results suggest that measuring refraction along the vertical meridian is preferred for screening studies with the eccentric photorefractor.

Leakage flow-induced vibration of an eccentric tube-in-tube slip joint

International Nuclear Information System (INIS)

Mulcahy, T.M.

1985-08-01

Eccentricity of a specific slip-joint design separating two cantilevered, telescoping tubes did not create any self-excited lateral vibrations that had not been observed previously for a concentric slip joint. In fact, the eccentricity made instabilities less likely to occur, but only marginally. Most important, design rules previously established to avoid instabilities for the concentric slip joint remain valid for the eccentric slip joint. 6 refs., 9 figs., 2 tabs

Charge collection control using retrograde well tested by proton microprobe irradiation

International Nuclear Information System (INIS)

Sayama, Hirokazu; Takai, Mikio; Kimura, Hiroshi; Ohno, Yoshikazu; Satoh, Shinichi; Sonoda, Kenichirou; Katani, Norihiko.

1993-01-01

Soft error reduction by high-energy ion-implanted layers has been investigated by novel evaluation techniques using high-energy proton microprobes. A retrograde well formed by 160 and 700 keV boron ion implantation could completely suppress soft errors induced by the proton microprobes at 400 keV. The proton-induced current revealed the charge collection efficiency for the retrograde well structure. The collected charge for the retrograde well in the soft-error mapping was proved to be lower than the critical charge of the measured DRAMs(dynamic random-access memories). Complementary use of soft-error mapping and ion-induced-current measurement could clarify well structures immune against soft errors. (author)

Neuromuscular and muscle-tendon system adaptations to isotonic and isokinetic eccentric exercise.

Science.gov (United States)

Guilhem, G; Cornu, C; Guével, A

2010-06-01

To present the properties of an eccentric contraction and compare neuromuscular and muscle-tendon system adaptations induced by isotonic and isokinetic eccentric trainings. An eccentric muscle contraction is characterized by the production of muscle force associated to a lengthening of the muscle-tendon system. This muscle solicitation can cause micro lesions followed by a regeneration process of the muscle-tendon system. Eccentric exercise is commonly used in functional rehabilitation for its positive effect on collagen synthesis but also for resistance training to increase muscle strength and muscle mass in athletes. Indeed, eccentric training stimulates muscle hypertrophy, increases the fascicle pennation angle, fascicles length and neural activation, thus inducing greater strength gains than concentric or isometric training programs. Eccentric exercise is commonly performed either against a constant external load (isotonic) or at constant velocity (isokinetic), inducing different mechanical constraints. These different mechanical constraints could induce structural and neural adaptive strategies specific to each type of exercise. The literature tends to show that isotonic mode leads to a greater strength gain than isokinetic mode. This observation could be explained by a greater neuromuscular activation after IT training. However, the specific muscle adaptations induced by each mode remain difficult to determine due to the lack of standardized, comparative studies. 2010 Elsevier Masson SAS. All rights reserved.

The Gemini NICI planet-finding campaign: the orbit of the young exoplanet β Pictoris b

Energy Technology Data Exchange (ETDEWEB)

Nielsen, Eric L.; Liu, Michael C.; Chun, Mark; Ftaclas, Christ [Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States); Wahhaj, Zahed [European Southern Observatory, Alonso de Cordova 3107, Vitacura, Casilla 19001, Santiago (Chile); Biller, Beth A. [Institute for Astronomy, The University of Edinburgh, Royal Observatory, Blackford Hill, Edinburgh EH9 3HJ (United Kingdom); Hayward, Thomas L. [Gemini Observatory, Southern Operations Center, c/o AURA, Casilla 603, La Serena (Chile); Males, Jared R.; Close, Laird M.; Morzinski, Katie M.; Skemer, Andrew J.; Hinz, Philip M. [Steward Observatory, University of Arizona, 933 North Cherry Avenue, Tucson, AZ 85721 (United States); Kuchner, Marc J. [Goddard Space Flight Center, Code 667, Greenbelt, MD 20771 (United States); Rodigas, Timothy J. [Department of Terrestrial Magnetism, Carnegie Institute of Washington, 5241 Broad Branch Road, NW, Washington, DC 20015 (United States); Toomey, Douglas W. [Mauna Kea Infrared, LLC, 21 Pookela Street, Hilo, HI 96720 (United States)

2014-10-20

We present new astrometry for the young (12-21 Myr) exoplanet β Pictoris b taken with the Gemini/NICI and Magellan/MagAO instruments between 2009 and 2012. The high dynamic range of our observations allows us to measure the relative position of β Pic b with respect to its primary star with greater accuracy than previous observations. Based on a Markov Chain Monte Carlo analysis, we find the planet has an orbital semi-major axis of 9.1{sub −0.5}{sup +5.3} AU and orbital eccentricity <0.15 at 68% confidence (with 95% confidence intervals of 8.2-48 AU and 0.00-0.82 for semi-major axis and eccentricity, respectively, due to a long narrow degenerate tail between the two). We find that the planet has reached its maximum projected elongation, enabling higher precision determination of the orbital parameters than previously possible, and that the planet's projected separation is currently decreasing. With unsaturated data of the entire β Pic system (primary star, planet, and disk) obtained thanks to NICI's semi-transparent focal plane mask, we are able to tightly constrain the relative orientation of the circumstellar components. We find the orbital plane of the planet lies between the inner and outer disks: the position angle (P.A.) of nodes for the planet's orbit (211.8 ± 0.°3) is 7.4σ greater than the P.A. of the spine of the outer disk and 3.2σ less than the warped inner disk P.A., indicating the disk is not collisionally relaxed. Finally, for the first time we are able to dynamically constrain the mass of the primary star β Pic to 1.76{sub −0.17}{sup +0.18} M {sub ☉}.

Investigation of the Usability of Retrograded Flour in Meatball Production as A Structure Enhancer.

Science.gov (United States)

Dinçer, Elif Aykin; Büyükkurt, Özlem Kiliç; Candal, Cihadiye; Bilgiç, Büşra Fatma; Erbaş, Mustafa

2018-02-01

This study aimed to research the possibilities of using retrograded flour produced in the laboratory environment in meatballs and the characteristics of these meatballs. In the use of retrograded flour to produce meatballs, it was ensured that the meatball properties, with respect to chemical, physical and sensorial aspects, were comparable to those of meatballs produced with bread (traditional) and rusk flour (commercial). The cooking loss of meatballs produced with using retrograded flour was similar to that of commercial meatballs. Doses of retrograded flour from 5% to 20% led to a significant decrease in cooking loss, from 21.95% to 6.19%, and in the diameter of meatballs, from 18.60% to 12.74%, but to an increase in the thickness of meatballs, from 28.82% to 41.39% compared to the control. The increase of a * and b * values was shown in that the meatballs were browned on cooking with increasing retrograded flour doses because of non-enzymatic reactions. The springiness of the traditional meatballs was significantly higher than that of the other meatballs. This might have been due to the bread crumbs having a naturally springy structure. Moreover, the addition of retrograded flour in the meatballs significantly ( p meatballs with respect to textural properties. Accordingly, it is considered that the use of 10% retrograded flour is ideal to improve the sensorial values of meatballs and the properties of their structure.

An indigenous economic technique of positive pressure retrograde urethrography in female patients

Directory of Open Access Journals (Sweden)

H Singh

2001-01-01

Full Text Available Usually double balloon catheter is required forpositive pressure retrograde urethrography in females. We describe a technique of positive pressure retrograde urethrography using Foley catheter and rubber stopper, inexpensive and could be adopted in any hospital or radiological suite.

Deterioration of cholestasis after endoscopic retrograde cholangiography in advanced primary sclerosing cholangitis

NARCIS (Netherlands)

Beuers, U.; Spengler, U.; Sackmann, M.; Paumgartner, G.; Sauerbruch, T.

1992-01-01

Complications of endoscopic retrograde cholangiography specific to patients with primary sclerosing cholangitis have not yet been reported. We observed transient rises of serum bilirubin after diagnostic endoscopic retrograde cholangiography in five of 15 patients and persistent rises in three of 15

Illuminating massive black holes with white dwarfs: orbital dynamics and high-energy transients from tidal interactions

International Nuclear Information System (INIS)

MacLeod, Morgan; Goldstein, Jacqueline; Ramirez-Ruiz, Enrico; Guillochon, James; Samsing, Johan

2014-01-01

White dwarfs (WDs) can be tidally disrupted only by massive black holes (MBHs) with masses less than ∼10 5 M ☉ . These tidal interactions feed material to the MBH well above its Eddington limit, with the potential to launch a relativistic jet. The corresponding beamed emission is a promising indication of an otherwise quiescent MBH of relatively low mass. We show that the mass transfer history, and thus the light curve, is quite different when the disruptive orbit is parabolic, eccentric, or circular. The mass lost each orbit exponentiates in the eccentric-orbit case, leading to the destruction of the WD after several tens of orbits. We examine the stellar dynamics of clusters surrounding MBHs to show that single-passage WD disruptions are substantially more common than repeating encounters. The 10 49 erg s –1 peak luminosity of these events makes them visible to cosmological distances. They may be detectible at rates of as many as tens per year by instruments like Swift. In fact, WD-disruption transients significantly outshine their main-sequence star counterparts and are the tidal interaction most likely to be detected arising from MBHs with masses less than 10 5 M ☉ . The detection or nondetection of such WD-disruption transients by Swift is, therefore, a powerful tool to constrain the lower end of the MBH mass function. The emerging ultralong gamma-ray burst class of events all have peak luminosities and durations reminiscent of WD disruptions, offering a hint that WD-disruption transients may already be present in existing data sets.

Retrograde Tibiopedal Access as a Bail-Out Procedure for Endovascular Intervention Complications

Directory of Open Access Journals (Sweden)

Ahmed Amro

2016-01-01

Full Text Available Introduction. Retrograde pedal access has been well described in the literature as a secondary approach for limb salvage in critical limb ischemia (CLI patients. In this manuscript we are presenting a case where retrograde tibiopedal access has been used as a bail-out procedure for the management of superficial femoral artery (SFA intervention complications. Procedure/Technique. After development of a perforation while trying to cross the totally occluded mid SFA using the conventional CFA access, we were able to cross the mid SFA lesion after accessing the posterior tibial artery in a retrograde fashion and delivered a self-expanding stent which created a flap that sealed the perforation without the need for covered stent. Conclusion. Retrograde tibiopedal access is a safe and effective approach for delivery of stents from the distal approach and so can be used as a bail-out technique for SFA perforation.

Do slow orbital periodicities appear in the record of earth's magnetic reversals?

Science.gov (United States)

Stothers, Richard B.

1987-01-01

Time-series spectral analysis has been performed on the dates of geomagnetic reversals of the last 20 Myr BP and earlier. Possible evidence is found from the presence of high spectral peaks for two very long periodicities, 0.4 Myr and 1.3 Myr, that may be associated with slow variations of the earth's orbital eccentricity as predicted by Berger. However, statistical significance tests and a number of other arguments do not confirm the two detections.

Preservation of eccentric strength in older adults: Evidence, mechanisms and implications for training and rehabilitation.

Science.gov (United States)

Roig, Marc; Macintyre, Donna L; Eng, Janice J; Narici, Marco V; Maganaris, Constantinos N; Reid, W Darlene

2010-06-01

Overall reductions in muscle strength typically accompany the aging process. However, older adults show a relatively preserved capacity of producing eccentric strength. The preservation of eccentric strength in older adults is a well-established phenomenon, occurring indiscriminately across different muscle groups, independent of age-related architectural changes in muscle structure and velocity of movement. The mechanisms for the preservation of eccentric strength appear to be mechanical and cellular in origin and include both passive and active elements regulating muscle stiffness. The age-related accumulation of non-contractile material in the muscle-tendon unit increases passive stiffness, which might offer mechanical advantage during eccentric contractions. In addition, the preserved muscle tension and increased instantaneous stiffness of old muscle fibers during stretch increase active stiffness, which might enhance eccentric strength. The fact that the preservation of eccentric strength is present in people with chronic conditions when compared to age-matched healthy controls indicates that the aging process per se does not exclusively mediate the preservation of eccentric strength. Physical inactivity, which is common in elderly and people with chronic conditions, is a potential factor regulating the preservation of eccentric strength. When compared to concentric strength, the magnitude of preservation of eccentric strength in older adults ranges from 2% to 48% with a mean value of 21.6% from all studies. This functional reserve of eccentric strength might be clinically relevant, especially to initiate resistance training and rehabilitation programs in individuals with low levels of strength. 2010 Elsevier Inc. All rights reserved.

Postoperative eccentric macular holes after vitrectomy and internal limiting membrane peeling.

Science.gov (United States)

Brouzas, Dimitrios; Dettoraki, Maria; Lavaris, Anastasios; Kourvetaris, Dimitrios; Nomikarios, Nikolaos; Moschos, Marilita M

2017-06-01

The purpose of this study was to describe the incidence, clinical characteristics, and outcome of eccentric macular holes presenting after vitrectomy and internal limiting membrane (ILM) peeling for the treatment of macular pathology and discuss the pathogenesis of holes formation. A retrospective, noncomparative, interventional case-series study of five patients who developed eccentric macular holes postoperatively following vitrectomy in 198 consecutive patients who underwent ILM peeling for idiopathic macular hole and epiretinal membrane formation between 2008 and 2015. Five patients (2.5 %) developed full-thickness eccentric macular holes postoperatively. Three patients presented with a single eccentric macular hole, one patient had an eccentric hole after a failed idiopathic macular hole surgery and one patient developed four eccentric macular holes. The mean diameter of the holes was 584 μm (range 206-1317 μm) and the average time of holes formation after vitrectomy was 27.7 weeks (range 1-140 weeks). Postoperative best-corrected visual acuity ranged from "counting fingers" to 20/25. The eyes with the holes distant from the fovea had the best final visual acuity. No further intervention was attempted and no complications occurred. The mean follow-up time was 26.8 months. The postoperative macular holes after vitrectomy and ILM peeling were variable in number, size, and time of appearance but remained stable and were not associated with any complications. The pathogenesis of macular holes is most consistent with contraction of the residual ILM or secondary epimacular proliferation probably stimulated by ILM peeling.

On the electrodynamic explanation of the retrograde motion of the electric arc

International Nuclear Information System (INIS)

Hong, J.S.; Allen, J.E.

1992-01-01

The retrograde motion of the cathode spot in a transverse magnetic field is one of the more intriguing phenomena of the electric arc. Although the phenomenon has been known for nearly ninety years since its discovery by Stark and has stimulated numerous investigations which result in many models giving explanation from different points of view, there is still no theory that can account both qualitatively and quantitatively for all the observations. Most of the explanations of the retrograde motion involve the study of cathode processes to give the preferential formation of new cathode spots along the retrograde direction. One line of explanation, which is rather different from the others, is based on electrodynamics. In this approach the retrograde motion is treated as an electrodynamic event. The present paper develops the theory suggested by Robson and von Engel. A more complete model is proposed and studied in detail by means of electromagnetic field theory. The results obtained not only show that the retrograde motion can be explained by the electrodynamics, but also confirm that the average current density on the cathode spot must be around the order of 10 12 A/m 2 . Recent studies of spot current density have shown values of this order. (author) 22 refs., 4 figs., 1 tab

Treatment of lower extremity arterial occlusive through retrograde access

International Nuclear Information System (INIS)

Liu Xueqiang; Guo Pingfan; Zhang Jinchi; Cai Fanggang

2012-01-01

Objective: To explore the clinical significance of retrograde access for the interventional treatment of lower extremity arterial occlusive diseases when the occluded segment of lower extremity artery could not be reached through antegrade access. Methods: Twenty-seven cases (male 17, female 10; age range 32-89 years) were retrospectively investigated, including 18 with lower limb arteriosclerosis obliterans, 7 with diabetic foot and 2 with thromboangiitis obliterans. According to the Fontaine staging, 6 cases were classified as Fontaine Ⅱ, 11 were classified as Fontaine Ⅲ and 10 were classified as Fontaine Ⅳ. All cases underwent endovascular operation through antegrade access first with an attempt to cross the occlusive segment, but in vain. So retrograde access was tried via puncture of pedis dorsalis or posterior tibial artery or exposure of lateral branches of posterior tibial artery, peroneal artery or dorsal artery by open surgery,which followed by Percutaneous transluminal angiography and (or) stenting. Results: The operation through retrograde access was successful in all cases with obvious improvement of ischemic symptoms. Hematoma at the puncture site occurred in 3 patients, and paresthesia of toes occurred in 1 after dorsalis pedis arteriotomy. No severe perioperative complication occurred. The average ankle brachial index increased from 0.37 ± 0.11 preoperatively to 0.85 ± 0.12 postoperatively. Conclusions: Retrograde access could be used as an alternative strategy in lower extremity arterial occlusive diseases when the occluded segment could not reach through antegrade access. (authors)

Astrophysical parameters and orbital solution of the peculiar X-ray transient IGR J00370+6122

Science.gov (United States)

González-Galán, A.; Negueruela, I.; Castro, N.; Simón-Díaz, S.; Lorenzo, J.; Vilardell, F.

2014-06-01

Context. BD + 60° 73 is the optical counterpart of the X-ray source IGR J00370+6122, a probable accretion-powered X-ray pulsar. The X-ray light curve of this binary system shows clear periodicity at 15.7 d, which has been interpreted as repeated outbursts around the periastron of an eccentric orbit. Aims: We aim to characterise the binary system IGR J00370+6122 by deriving its orbital and physical parameters. Methods: We obtained high-resolution spectra of BD + 60° 73 at different epochs. We used the fastwind code to generate a stellar atmosphere model to fit the observed spectrum and obtain physical magnitudes. The synthetic spectrum was used as a template for cross-correlation with the observed spectra to measure radial velocities. The radial velocity curve provided an orbital solution for the system. We also analysed the RXTE/ASM and Swift/BAT light curves to confirm the stability of the periodicity. Results: BD + 60° 73 is a BN0.7 Ib low-luminosity supergiant located at a distance ~3.1 kpc, in the Cas OB4 association. We derive Teff = 24 000 K and log gc = 3.0, and chemical abundances consistent with a moderately high level of evolution. The spectroscopic and evolutionary masses are consistent at the 1-σ level with a mass M∗ ≈ 15 M⊙. The recurrence time of the X-ray flares is the orbital period of the system. The neutron star is in a high-eccentricity (e = 0.56 ± 0.07) orbit, and the X-ray emission is strongly peaked around orbital phase φ = 0.2, though the observations are consistent with some level of X-ray activity happening at all orbital phases. Conclusions: The X-ray behaviour of IGR J00370+6122 is reminiscent of "intermediate" supergiant X-ray transients, though its peak luminosity is rather low. The orbit is somewhat wider than those of classical persistent supergiant X-ray binaries, which when combined with the low luminosity of the mass donor, explains the low X-ray luminosity. IGR J00370+6122 will very likely evolve towards a persistent

Secular Orbit Evolution in Systems with a Strong External Perturber—A Simple and Accurate Model

Energy Technology Data Exchange (ETDEWEB)

Andrade-Ines, Eduardo [Institute de Mécanique Céleste et des Calcul des Éphémérides—Observatoire de Paris, 77 Avenue Denfert Rochereau, F-75014 Paris (France); Eggl, Siegfried, E-mail: eandrade.ines@gmail.com, E-mail: siegfried.eggl@jpl.nasa.gov [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, 91109 Pasadena, CA (United States)

2017-04-01

We present a semi-analytical correction to the seminal solution for the secular motion of a planet’s orbit under gravitational influence of an external perturber derived by Heppenheimer. A comparison between analytical predictions and numerical simulations allows us to determine corrective factors for the secular frequency and forced eccentricity in the coplanar restricted three-body problem. The correction is given in the form of a polynomial function of the system’s parameters that can be applied to first-order forced eccentricity and secular frequency estimates. The resulting secular equations are simple, straight forward to use, and improve the fidelity of Heppenheimers solution well beyond higher-order models. The quality and convergence of the corrected secular equations are tested for a wide range of parameters and limits of its applicability are given.

High degree gravitational sensitivity from Mars orbiters for the GMM-1 gravity model

Science.gov (United States)

Lerch, F. J.; Smith, D. E.; Chan, J. C.; Patel, G. B.; Chinn, D. S.

1994-01-01

Orbital sensitivity of the gravity field for high degree terms (greater than 30) is analyzed on satellites employed in a Goddard Mars Model GMM-1, complete in spherical harmonics through degree and order 50. The model is obtained from S-band Doppler data on Mariner 9 (M9), Viking Orbiter 1 (VO1), and Viking Orbiter 2 (VO2) spacecraft, which were tracked by the NASA Deep Space Network on seven different highly eccentric orbits. The main sensitivity of the high degree terms is obtained from the VO1 and VO2 low orbits (300 km periapsis altitude), where significant spectral sensitivity is seen for all degrees out through degree 50. The velocity perturbations show a dominant effect at periapsis and significant effects out beyond the semi-latus rectum covering over 180 degrees of the orbital groundtrack for the low altitude orbits. Because of the wideband of periapsis motion covering nearly 180 degrees in w and +39 degrees in latitude coverage, the VO1 300 km periapsis altitude orbit with inclination of 39 degrees gave the dominant sensitivity in the GMM-1 solution for the high degree terms. Although the VO2 low periapsis orbit has a smaller band of periapsis mapping coverage, it strongly complements the VO1 orbit sensitivity for the GMM-1 solution with Doppler tracking coverage over a different inclination of 80 degrees.

Development of online cable eccentricity detection system based on X-ray CCD

International Nuclear Information System (INIS)

Chen Jianzhen; Li Bin; Wei Kaixia; Guo Lanying; Qu Guopu

2008-01-01

An improved technology of online cable eccentricity detection, based on X-ray CCD, greatly improves the measuring precision and the responding speed. The theory of eccentricity measuring based on X-ray CCD, and the structure of an apparatus are described. The apparatus is composed of scanning drive subsystem, X-ray generation components, data acquiring subsystem and high performance computer system. The measuring results are also presented. The features of this cable eccentricity detection technology are compared with the features of other technologies. (authors)

The TWA 3 Young Triple System: Orbits, Disks, Evolution

Energy Technology Data Exchange (ETDEWEB)

Kellogg, Kendra [Department of Physics and Astronomy, The University of Western Ontario, London, ON N6A 3K7 (Canada); Prato, L.; Avilez, I.; Wasserman, L. H.; Levine, S. E.; Bosh, A. S. [Lowell Observatory, 1400 West Mars Hill Road, Flagstaff, AZ 86001 (United States); Torres, Guillermo [Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138 (United States); Schaefer, G. H. [The CHARA Array of Georgia State University, Mount Wilson Observatory, Mount Wilson, CA 91023 (United States); Ruíz-Rodríguez, D. [Research School of Astronomy and Astrophysics, Australian National University, Canberra, ACT 2611 (Australia); Bonanos, Alceste Z. [IAASARS, National Observatory of Athens, 15236 Penteli (Greece); Guenther, E. W. [Thüringer Landessternwarte Tautenburg, D-07778 Tautenburg (Germany); Neuhäuser, R. [Astrophysikalisches Institut und Universitäts-Sternwarte, FSU Jena, Schillergäßchen 2-3, D-07745 Jena (Germany); Morzinski, Katie M.; Close, Laird; Hinz, Phil; Males, Jared R. [Steward Observatory, University of Arizona, 933 N. Cherry Ave, Tucson, AZ 85721 (United States); Bailey, Vanessa, E-mail: kkellogg@uwo.ca, E-mail: lprato@lowell.edu [Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics, Stanford University, Stanford, CA, 94305 (United States)

2017-08-01

We have characterized the spectroscopic orbit of the TWA 3A binary and provide preliminary families of probable solutions for the TWA 3A visual orbit, as well as for the wide TWA 3A–B orbit. TWA 3 is a hierarchical triple located at 34 pc in the ∼10 Myr old TW Hya association. The wide component separation is 1.″55; the close pair was first identified as a possible binary almost 20 years ago. We initially identified the 35-day period orbital solution using high-resolution infrared spectroscopy that angularly resolved the A and B components. We then refined the preliminary orbit by combining the infrared data with a reanalysis of our high-resolution optical spectroscopy. The orbital period from the combined spectroscopic solution is ∼35 days, the eccentricity is ∼0.63, and the mass ratio is ∼0.84; although this high mass ratio would suggest that optical spectroscopy alone should be sufficient to identify the orbital solution, the presence of the tertiary B component likely introduced confusion in the blended optical spectra. Using millimeter imaging from the literature, we also estimate the inclinations of the stellar orbital planes with respect to the TWA 3A circumbinary disk inclination and find that all three planes are likely misaligned by at least ∼30°. The TWA 3A spectroscopic binary components have spectral types of M4.0 and M4.5; TWA 3B is an M3. We speculate that the system formed as a triple, is bound, and that its properties were shaped by dynamical interactions between the inclined orbits and disk.

Experimental investigation of the abrasive crown dynamics in orbital atherectomy.

Science.gov (United States)

Zheng, Yihao; Belmont, Barry; Shih, Albert J

2016-07-01

Orbital atherectomy is a catheter-based minimally invasive procedure to modify the plaque within atherosclerotic arteries using a diamond abrasive crown. This study was designed to investigate the crown motion and its corresponding contact force with the vessel. To this end, a transparent arterial tissue-mimicking phantom made of polyvinyl chloride was developed, a high-speed camera and image processing technique were utilized to visualize and quantitatively analyze the crown motion in the vessel phantom, and a piezoelectric dynamometer measured the forces on the phantom during the procedure. Observed under typical orbital atherectomy rotational speeds of 60,000, 90,000, and 120,000rpm in a 4.8mm caliber vessel phantom, the crown motion was a combination of high-frequency rotation at 1000, 1500, and 1660.4-1866.1Hz and low-frequency orbiting at 18, 38, and 40Hz, respectively. The measured forces were also composed of these high and low frequencies, matching well with the rotation of the eccentric crown and the associated orbital motion. The average peak force ranged from 0.1 to 0.4N at different rotational speeds. Copyright © 2016 IPEM. Published by Elsevier Ltd. All rights reserved.

Retrograde Jejuno-Jejunal Intussusception after Total Gastrectomy

Directory of Open Access Journals (Sweden)

Akira Yoneda

2008-08-01

Full Text Available An eighty-year-old female was transferred to the hospital after experiencing abdominal pain and nausea. She had had a history of total gastrectomy for gastric cancer 14 years previously. Abdominal X-ray revealed a localized expansion of the small bowel. Computed tomography revealed a mass with a lamellar structure in a concentric circle. With a tentative diagnosis of small bowel obstruction due to intussusception, she underwent emergency operation. Laparotomy revealed a retrograde jejuno-jejunal intussusception. Bowel resection was performed due to the severe ischemic damage. All reported intussusception cases after total gastrectomy displayed retrograde characteristics and could occur both during the early and late period after surgery. It is important to consider the possibility of intussusception for patients presenting with acute abdomen who have previously undergone gastric resection.

3D spin-orbit angle of Kepler-25 and HAT-P-7

Directory of Open Access Journals (Sweden)

Benomar Othman

2015-01-01

Full Text Available The number of discovered exoplanets now exceeds 1500, mostly due to the Kepler space instrument observations. Many of these planet orbit in less than a week around their host stars. This implies that the inward migration of those planets is a basic ingredient of successful theories of planet formation and evolution. Several mechanisms have been proposed to explain the observed periods, which lead to different orbit eccentricity and obliquity distributions. Here we summarise and discuss the results of obliquities for two Kepler stars: HAT-P-7 and Kepler-25. These are interesting stellar systems as we could carry out a joint analysis using asteroseismology, transit lightcurve and the Rossiter-McLaughlin effect in order to measure the three dimensional obliquity.

Eccentric connectivity index of chemical trees

International Nuclear Information System (INIS)

Haoer, R. S.; Atan, K. A.; Said, M. R. Md.; Khalaf, A. M.; Hasni, R.

2016-01-01

Let G = (V, E) be a simple connected molecular graph. In such a simple molecular graph, vertices and edges are depicted atoms and chemical bonds respectively, we refer to the sets of vertices by V (G) and edges by E (G). If d(u, v) be distance between two vertices u, v ∈ V(G) and can be defined as the length of a shortest path joining them. Then, the eccentricity connectivity index (ECI) of a molecular graph G is ξ(G) = ∑_v_∈_V_(_G_) d(v) ec(v), where d(v) is degree of a vertex v ∈ V(G). ec(v) is the length of a greatest path linking to another vertex of v. In this study, we focus the general formula for the eccentricity connectivity index (ECI) of some chemical trees as alkenes.

An Eccentrically Biased Rehabilitation Program Early after TKA Surgery

Directory of Open Access Journals (Sweden)

Robin L. Marcus

2011-01-01

Full Text Available Rehabilitation services are less-studied aspects of the management following total knee arthroplasty (TKA despite long-term suboptimal physical functioning and chronic deficits in muscle function. This paper describes the preliminary findings of a six-week (12 session eccentrically-biased rehabilitation program targeted at deficits in physical function and muscle function, initiated one month following surgery. A quasiexperimental, one group, pretest-posttest study with thirteen individuals (6 female, 7 male; mean age 57±7 years examined the effectiveness of an eccentrically-biased rehabilitation program. The program resulted in improvements in the primary physical function endpoints (SF-36 physical component summary and the six-minute walk test with increases of 59% and 47%, respectively. Muscle function endpoints (knee extension strength and power also increased 107% and 93%, respectively. Eccentrically-biased exercise used as an addition to rehabilitation may help amplify and accelerate physical function following TKA surgery.

Eccentric exercise training as a countermeasure to non-weight-bearing soleus muscle atrophy

Science.gov (United States)

Kirby, Christopher R.; Ryan, Mirelle J.; Booth, Frank W.

1992-01-01

This investigation tested whether eccentric resistance training could prevent soleus muscle atrophy during non-weight bearing. Adult female rats were randomly assigned to either weight bearing +/- intramuscular electrodes or non-weight bearing +/- intramuscular electrodes groups. Electrically stimulated maximal eccentric contractions were performed on anesthetized animals at 48-h intervals during the 10-day experiment. Non-weight bearing significantly reduced soleus muscle wet weight (28-31 percent) and noncollagenous protein content (30-31 percent) compared with controls. Eccentric exercise training during non-weight bearing attenuated but did not prevent the loss of soleus muscle wet weight and noncollagenous protein by 77 and 44 percent, respectively. The potential of eccentric exercise training as an effective and highly efficient counter-measure to non-weight-bearing atrophy is demonstrated in the 44 percent attenuation of soleus muscle noncollagenous protein loss by eccentric exercise during only 0.035 percent of the total non-weight-bearing time period.

Focal retrograde amnesia: voxel-based morphometry findings in a case without MRI lesions.

Directory of Open Access Journals (Sweden)

Bernhard Sehm

Full Text Available Focal retrograde amnesia (FRA is a rare neurocognitive disorder presenting with an isolated loss of retrograde memory. In the absence of detectable brain lesions, a differentiation of FRA from psychogenic causes is difficult. Here we report a case study of persisting FRA after an epileptic seizure. A thorough neuropsychological assessment confirmed severe retrograde memory deficits while anterograde memory abilities were completely normal. Neurological and psychiatric examination were unremarkable and high-resolution MRI showed no neuroradiologically apparent lesion. However, voxel-based morphometry (VBM-comparing the MRI to an education-, age-and sex-matched control group (n = 20 disclosed distinct gray matter decreases in left temporopolar cortex and a region between right posterior parahippocampal and lingual cortex. Although the results of VBM-based comparisons between a single case and a healthy control group are generally susceptible to differences unrelated to the specific symptoms of the case, we believe that our data suggest a causal role of the cortical areas detected since the retrograde memory deficit is the preeminent neuropsychological difference between patient and controls. This was paralleled by grey matter differences in central nodes of the retrograde memory network. We therefore suggest that these subtle alterations represent structural correlates of the focal retrograde amnesia in our patient. Beyond the implications for the diagnosis and etiology of FRA, our results advocate the use of VBM in conditions that do not show abnormalities in clinical radiological assessment, but show distinct neuropsychological deficits.

Eccentric rehabilitation exercise increases peritendinous type I collagen synthesis in humans with Achilles tendinosis

DEFF Research Database (Denmark)

Langberg, Henning; Ellingsgaard, Helga; Madsen, Thomas

2007-01-01

It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime on...... in the healthy tendons. The clinical effect of the 12 weeks of eccentric training was determined by using a standardized loading procedure of the Achilles tendons showing a decrease in pain in all the chronic injured tendons (VAS before 44+/-9, after 13+/-9; P......It has been shown that 12 weeks of eccentric heavy resistance training can reduce pain in runners suffering from chronic Achilles tendinosis, but the mechanism behind the effectiveness of this treatment is unknown. The present study investigates the local effect of an eccentric training regime...... of heavy-resistance eccentric training apart from their regular training and soccer activity. Before and after the training period the tissue concentration of indicators of collagen turnover was measured by the use of the microdialysis technique. After training, collagen synthesis was increased...

The role of eccentric regime of leg muscle work in alpine skiing

Directory of Open Access Journals (Sweden)

Ropret Robert

2017-01-01

Full Text Available Alpine skiing is characterized by a great number of leg movements with muscle contractions in eccentric regime. The role of these movements is to absorb gravitation and inertial forces, manage skis more precisely and maintain balance. Recent studies have determined the volume, duration and intenisty of eccentric contractions as well as the basic characteristics of movement amplitudes and velocities. Based on the previous findings the experiments involving eccentric training using a bicycle ergometer confirmed a positive impact that this kind of training has on increasing maximum power, strength, endurance, coordination, injury prevention, metabolic work efficiency, more efficient work with longer muscle length and its role in miming skiers' movements. This paper is an review of the studies so far in the field of kinematics, skiing dynamics and the effect of eccentric training on the development of athletes' performances.

Development of a new universal machine device for eccentric shafts processing

Directory of Open Access Journals (Sweden)

Михайло Володимирович Маргуліс

2015-11-01

Full Text Available The analysis of the existing lathe devices for machining of eccentric details and the reasons for the development of a new universal machine device– a shifting lathe center-have been described in the article. The device design, its operating principle, the main parts functions and elements of the case were described and illustrated One of the most complicated cases of eccentric shaft turning, that is turning design and scheme of the eccentric shaft of precessional harmonic drive with intermediate rolling bodies when the proposed device was used was described in the article. The shifting lathe center can reduce the complexity of the machine tool for turning eccentric shafts configuration. The ability to install the shifting center in the tailstock and headstock of the lathe, and the availability of the leash makes it possible to turn various eccentric parts, conical surfaces, to apply the device to compensate for the emerging taper in cylindrical shafts processing. All the above mentioned makes the device universal. The specific feature of this device is the use of a ball center and the connection of the centering element with the adjusting screw by a fine thread screw, this increasing the precision machining. The protective cover of the device makes it possible to reduce the chance of possible injury from protruding parts of the device, namely the leash and the centering element

Verifying black hole orbits with gravitational spectroscopy

International Nuclear Information System (INIS)

Drasco, Steve

2009-01-01

Gravitational waves from test masses bound to geodesic orbits of rotating black holes are simulated, using Teukolsky's black hole perturbation formalism, for about ten thousand generic orbital configurations. Each binary radiates power exclusively in modes with frequencies that are integer-linear combinations of the orbit's three fundamental frequencies. General spectral properties are found with a survey of orbits about a black hole taken to be rotating at 80% of the maximal spin. The orbital eccentricity is varied from 0.1 to 0.9. Inclination ranges from 20 deg. to 160 deg. and comes to within 20 deg. of polar. Semilatus rectum is varied from 1.2 to 3 times the value at the innermost stable circular orbits. The following general spectral properties are found: (i) 99% of the radiated power is typically carried by a few hundred modes, and at most by about a thousand modes, (ii) the dominant frequencies can be grouped into a small number of families defined by fixing two of the three integer frequency multipliers, and (iii) the specifics of these trends can be qualitatively inferred from the geometry of the orbit under consideration. Detections using triperiodic analytic templates modeled on these general properties would constitute a verification of radiation from an adiabatic sequence of black hole orbits and would recover the evolution of the fundamental orbital frequencies. In an analogy with ordinary spectroscopy, this would compare to observing the Bohr model's atomic hydrogen spectrum without being able to rule out alternative atomic theories or nuclei. The suitability of such a detection technique is demonstrated using snapshots computed at 12-hour intervals throughout the last three years before merger of a kludged inspiral. The system chosen is typical of those thought to occur in galactic nuclei and to be observable with space-based gravitational wave detectors like LISA. Because of circularization, the number of excited modes decreases as the binary

On the Existence of Regular and Irregular Outer Moons Orbiting the Pluto–Charon System

Energy Technology Data Exchange (ETDEWEB)

Michaely, Erez; Perets, Hagai B.; Grishin, Evgeni [Physics Department, Technion—Israel Institute of Technology, Haifa 3200004 (Israel)

2017-02-10

The dwarf planet Pluto is known to host an extended system of five co-planar satellites. Previous studies have explored the formation and evolution of the system in isolation, neglecting perturbative effects by the Sun. Here we show that secular evolution due to the Sun can strongly affect the evolution of outer satellites and rings in the system, if such exist. Although precession due to extended gravitational potential from the inner Pluto–Charon binary quench such secular evolution up to a {sub crit} ∼ 0.0035 au (∼0.09 R {sub Hill} the Hill radius; including all of the currently known satellites), outer orbits can be significantly altered. In particular, we find that co-planar rings and satellites should not exist beyond a {sub crit}; rather, satellites and dust particles in these regions secularly evolve on timescales ranging between 10{sup 4} and 10{sup 6} years, and quasi-periodically change their inclinations and eccentricities through secular evolution (Lidov–Kozai oscillations). Such oscillations can lead to high inclinations and eccentricities, constraining the range where such satellites (and dust particles) can exist without crossing the orbits of the inner satellites or crossing the outer Hill stability range. Outer satellites, if such exist are therefore likely to be irregular satellites, with orbits limited to be non-circular and/or highly inclined. Current observations, including the recent data from the New-Horizons mission explored only inner regions (<0.0012 au) and excluded the existence of additional satellites; however, the irregular satellites discussed here should reside farther, in the yet uncharted regions around Pluto.

On the Existence of Regular and Irregular Outer Moons Orbiting the Pluto–Charon System

International Nuclear Information System (INIS)

Michaely, Erez; Perets, Hagai B.; Grishin, Evgeni

2017-01-01

The dwarf planet Pluto is known to host an extended system of five co-planar satellites. Previous studies have explored the formation and evolution of the system in isolation, neglecting perturbative effects by the Sun. Here we show that secular evolution due to the Sun can strongly affect the evolution of outer satellites and rings in the system, if such exist. Although precession due to extended gravitational potential from the inner Pluto–Charon binary quench such secular evolution up to a crit ∼ 0.0035 au (∼0.09 R Hill the Hill radius; including all of the currently known satellites), outer orbits can be significantly altered. In particular, we find that co-planar rings and satellites should not exist beyond a crit ; rather, satellites and dust particles in these regions secularly evolve on timescales ranging between 10 4 and 10 6 years, and quasi-periodically change their inclinations and eccentricities through secular evolution (Lidov–Kozai oscillations). Such oscillations can lead to high inclinations and eccentricities, constraining the range where such satellites (and dust particles) can exist without crossing the orbits of the inner satellites or crossing the outer Hill stability range. Outer satellites, if such exist are therefore likely to be irregular satellites, with orbits limited to be non-circular and/or highly inclined. Current observations, including the recent data from the New-Horizons mission explored only inner regions (<0.0012 au) and excluded the existence of additional satellites; however, the irregular satellites discussed here should reside farther, in the yet uncharted regions around Pluto.

An Intelligent Harmonic Synthesis Technique for Air-Gap Eccentricity Fault Diagnosis in Induction Motors

Science.gov (United States)

Li, De Z.; Wang, Wilson; Ismail, Fathy

2017-11-01

Induction motors (IMs) are commonly used in various industrial applications. To improve energy consumption efficiency, a reliable IM health condition monitoring system is very useful to detect IM fault at its earliest stage to prevent operation degradation, and malfunction of IMs. An intelligent harmonic synthesis technique is proposed in this work to conduct incipient air-gap eccentricity fault detection in IMs. The fault harmonic series are synthesized to enhance fault features. Fault related local spectra are processed to derive fault indicators for IM air-gap eccentricity diagnosis. The effectiveness of the proposed harmonic synthesis technique is examined experimentally by IMs with static air-gap eccentricity and dynamic air-gap eccentricity states under different load conditions. Test results show that the developed harmonic synthesis technique can extract fault features effectively for initial IM air-gap eccentricity fault detection.

Behaviour of Strengthened RC Frames with Eccentric Steel Braced Frames

Science.gov (United States)

Kamanli, Mehmet; Unal, Alptug

2017-10-01

After devastating earthquakes in recent years, strengthening of reinforced concrete buildings became an important research topic. Reinforced concrete buildings can be strengthened by steel braced frames. These steel braced frames may be made of concentrically or eccentrically indicated in Turkish Earthquake Code 2007. In this study pushover analysis of the 1/3 scaled 1 reinforced concrete frame and 1/3 scaled 4 strengthened reinforced concrete frames with internal eccentric steel braced frames were conducted by SAP2000 program. According to the results of the analyses conducted, load-displacement curves of the specimens were compared and evaluated. Adding eccentric steel braces to the bare frame decreased the story drift, and significantly increased strength, stiffness and energy dissipation capacity. In this strengthening method lateral load carrying capacity, stiffness and dissipated energy of the structure can be increased.

Light equation in eclipsing binary CV Boo: third body candidate in elliptical orbit

Science.gov (United States)

Bogomazov, A. I.; Kozyreva, V. S.; Satovskii, B. L.; Krushevska, V. N.; Kuznyetsova, Y. G.; Ehgamberdiev, S. A.; Karimov, R. G.; Khalikova, A. V.; Ibrahimov, M. A.; Irsmambetova, T. R.; Tutukov, A. V.

2016-12-01

A short period eclipsing binary star CV Boo is tested for the possible existence of additional bodies in the system with a help of the light equation method. We use data on the moments of minima from the literature as well as from our observations during 2014 May-July. A variation of the CV Boo's orbital period is found with a period of {≈}75 d. This variation can be explained by the influence of a third star with a mass of {≈}0.4 M_{⊙} in an eccentric orbit with e≈0.9. A possibility that the orbital period changes on long time scales is discussed. The suggested tertiary companion is near the chaotic zone around the central binary, so CV Boo represents an interesting example to test its dynamical evolution. A list of 14 minima moments of the binary obtained from our observations is presented.

Retrograde cholangiopancreatography in the diagnosis of biliary and pancreatic duct diseases

International Nuclear Information System (INIS)

Vasil'ev, Yu.D.; Sedletskaya, T.N.

1980-01-01

Results of retrograde cannulation with the aid of flexible fibroduodenoscopes with subsequent introduction of a contrast substance into biliary and pancreatic ducts are presented. The investigation is carried out on 120 patients with different diseases of hepatopancreatoduodenal zone. The standard technique of X-ray examination has been applied permitting to obtain the most exhaustive information. Using retrograde cholangiopancreatography revealed have been choledocholithiasis, deformation of biliary ducts after surgical intervention, pancreatic cyst, tumor of the main pancreatic duct etc. Results of investigation of biliary and pancreatic ducts using retrograde cannulation are reaffirmed with the data of operations on biliary tract in 72 patients. Intraoperational cholangiography has been carried out on 36 of them during operation. An attempt to cannulate big duodenal papilla in 12 patients proved to be ineffective. No complications have been observed during examination

THERMAL PHASES OF EARTH-LIKE PLANETS: ESTIMATING THERMAL INERTIA FROM ECCENTRICITY, OBLIQUITY, AND DIURNAL FORCING

International Nuclear Information System (INIS)

Cowan, Nicolas B.; Voigt, Aiko; Abbot, Dorian S.

2012-01-01

In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3× the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A pole-on observer

THERMAL PHASES OF EARTH-LIKE PLANETS: ESTIMATING THERMAL INERTIA FROM ECCENTRICITY, OBLIQUITY, AND DIURNAL FORCING

Energy Technology Data Exchange (ETDEWEB)

Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Research in Astrophysics and Department of Physics and Astronomy, Northwestern University, 2131 Tech Drive, Evanston, IL 60208 (United States); Voigt, Aiko [Max Planck Institute for Meteorology, Bundesstr. 53, D-20146 Hamburg (Germany); Abbot, Dorian S., E-mail: n-cowan@nortwestern.edu [Department of Geophysical Sciences, University of Chicago, 5734 South Ellis Avenue, Chicago, IL 60637 (United States)

2012-09-20

In order to understand the climate on terrestrial planets orbiting nearby Sun-like stars, one would like to know their thermal inertia. We use a global climate model to simulate the thermal phase variations of Earth analogs and test whether these data could distinguish between planets with different heat storage and heat transport characteristics. In particular, we consider a temperate climate with polar ice caps (like the modern Earth) and a snowball state where the oceans are globally covered in ice. We first quantitatively study the periodic radiative forcing from, and climatic response to, rotation, obliquity, and eccentricity. Orbital eccentricity and seasonal changes in albedo cause variations in the global-mean absorbed flux. The responses of the two climates to these global seasons indicate that the temperate planet has 3 Multiplication-Sign the bulk heat capacity of the snowball planet due to the presence of liquid water oceans. The obliquity seasons in the temperate simulation are weaker than one would expect based on thermal inertia alone; this is due to cross-equatorial oceanic and atmospheric energy transport. Thermal inertia and cross-equatorial heat transport have qualitatively different effects on obliquity seasons, insofar as heat transport tends to reduce seasonal amplitude without inducing a phase lag. For an Earth-like planet, however, this effect is masked by the mixing of signals from low thermal inertia regions (sea ice and land) with that from high thermal inertia regions (oceans), which also produces a damped response with small phase lag. We then simulate thermal light curves as they would appear to a high-contrast imaging mission (TPF-I/Darwin). In order of importance to the present simulations, which use modern-Earth orbital parameters, the three drivers of thermal phase variations are (1) obliquity seasons, (2) diurnal cycle, and (3) global seasons. Obliquity seasons are the dominant source of phase variations for most viewing angles. A

A new retrograde transillumination technique for videolaryngoscopic tracheal intubation

DEFF Research Database (Denmark)

Biro, P; Fried, E; Schlaepfer, M

2018-01-01

This single-centre, prospective trial was designed to assess the efficacy of a new retrograde transillumination device called the 'Infrared Red Intubation System' (IRRIS) to aid videolaryngoscopic tracheal intubation. We included 40 adult patients, who were undergoing elective urological surgery......-10])), credibility (10 (8-10 [5-10])) and ease of use (10 (9-10 [8-10])). Tracheal intubation with the system lasted 26 (16-32 [6-89]) s. No alternative technique of securing the airway was necessary. The lowest SpO2 during intubation was 98 (97-99 [91-100])%. We conclude that this method of retrograde...

Methods for determining the carrying capacity of eccentrically compressed concrete elements

Directory of Open Access Journals (Sweden)

Starishko Ivan Nikolaevich

2014-04-01

Full Text Available The author presents the results of calculations of eccentrically compressed elements in the ultimate limit state of bearing capacity, taking into account all possiblestresses in the longitudinal reinforcement from the R to the R , caused by different values of eccentricity longitudinal force. The method of calculation is based on the simultaneous solution of the equilibrium equations of the longitudinal forces and internal forces with the equilibrium equations of bending moments in the ultimate limit state of the normal sections. Simultaneous solution of these equations, as well as additional equations, reflecting the stress-strain limit state elements, leads to the solution of a cubic equation with respect to height of uncracked concrete, or with respect to the carrying capacity. According to the author it is a significant advantage over the existing methods, in which the equilibrium equations using longitudinal forces obtained one value of the height, and the equilibrium equations of bending moments - another. Theoretical studies of the author, in this article and the reasons to calculate specific examples showed that a decrease in the eccentricity of the longitudinal force in the limiting state of eccentrically compressed concrete elements height uncracked concrete height increases, the tension in the longitudinal reinforcement area gradually (not abruptly goes from a state of tension compression, and load-bearing capacity of elements it increases, which is also confirmed by the experimental results. Designed journalist calculations of eccentrically compressed elements for 4 cases of eccentric compression, instead of 2 - as set out in the regulations, fully cover the entire spectrum of possible cases of the stress-strain limit state elements that comply with the European standards for reinforced concrete, in particular Eurocode 2 (2003.

Brachial Artery Flow-mediated Dilation Following Exercise with Augmented Oscillatory and Retrograde Shear Rate

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Johnson Blair D

2012-08-01

Full Text Available Abstract Background Acute doses of elevated retrograde shear rate (SR appear to be detrimental to endothelial function in resting humans. However, retrograde shear increases during moderate intensity exercise which also enhances post-exercise endothelial function. Since SR patterns differ with the modality of exercise, it is important to determine if augmented retrograde SR during exercise influences post-exercise endothelial function. This study tested the hypothesis that (1 increased doses of retrograde SR in the brachial artery during lower body supine cycle ergometer exercise would attenuate post-exercise flow-mediated dilation (FMD in a dose-dependent manner, and (2 antioxidant vitamin C supplementation would prevent the attenuated post-exercise FMD response. Methods Twelve men participated in four randomized exercise sessions (90 W for 20 minutes on separate days. During three of the sessions, one arm was subjected to increased oscillatory and retrograde SR using three different forearm cuff pressures (20, 40, 60 mmHg (contralateral arm served as the control and subjects ingested placebo capsules prior to exercise. A fourth session with 60 mmHg cuff pressure was performed with 1 g of vitamin C ingested prior to the session. Results Post-exercise FMD following the placebo conditions were lower in the cuffed arm versus the control arm (arm main effect: P P > 0.05. Following vitamin C treatment, post-exercise FMD in the cuffed and control arm increased from baseline (P P > 0.05. Conclusions These results indicate that augmented oscillatory and retrograde SR in non-working limbs during lower body exercise attenuates post-exercise FMD without an evident dose–response in the range of cuff pressures evaluated. Vitamin C supplementation prevented the attenuation of FMD following exercise with augmented oscillatory and retrograde SR suggesting that oxidative stress contributes to the adverse effects of oscillatory and

Physiological comparison of concentric and eccentric arm cycling in males and females.

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C Martyn Beaven

Full Text Available Lower body eccentric exercise is well known to elicit high levels of muscular force with relatively low cardiovascular and metabolic strain. As a result, eccentric exercise has been successfully utilised as an adaptive stressor to improve lower body muscle function in populations ranging from the frail and debilitated, to highly-trained individuals. Here we investigate the metabolic, cardiorespiratory, and energy costs of upper body eccentric exercise in a healthy population. Seven men and seven women performed 4-min efforts of eccentric (ECC or concentric (CON arm cycling on a novel arm ergometer at workloads corresponding to 40, 60, and 80% of their peak workload as assessed in an incremental concentric trial. The heart rate, ventilation, cardiac output, respiratory exchange ratio, and blood lactate concentrations were all clearly greater in CON condition at all of the relative workloads (all p0.05. In contrast, delta efficiency (ηΔ, as previously defined by Coyle and colleagues in 1992, demonstrated a sex difference (men>women; p<0.05. Sex differences were also apparent in arteriovenous oxygen difference and heart rate during CON. Here, we reinforce the high-force, low cost attributes of eccentric exercise which can be generalised to the muscles of the upper body. Upper body eccentric exercise is likely to form a useful adjunct in debilitative, rehabilitative, and adaptive clinical exercise programs; however, reports of a shift towards an oxidative phenotype should be taken into consideration by power athletes. We suggest delta efficiency as a sensitive measure of efficiency that allowed the identification of sex differences.

Static Eccentricity Fault Recognition in Three-Phase Line Start Permanent Magnet Synchronous Motor Using Finite Element Method

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Mahdi Karami

2014-01-01

Full Text Available This paper is dedicated to investigating static eccentricity in a three-phase LSPMSM. The modeling of LSPMSM with static eccentricity between stator and rotor is developed using finite element method (FEM. The analytical expression for the permeance and flux components of nonuniform air-gap due to static eccentricity fault is discussed. Various indexes for static eccentricity detection using stator current signal of IM and permanent magnet synchronous motor (PMSM are presented. Since LSPMSM is composed of a rotor which is a combination of these two motors, the ability of these features is evaluated for static eccentricity diagnosis in LSPMSM. The simulated stator current signal of LSPMSM in the presence of static eccentricity is analyzed in frequency domain using power spectral density (PSD. It is demonstrated that static eccentricity fault generates a series of low frequency harmonic components in the form of sidebands around the fundamental frequency. Moreover, the amplitudes of these components increase in proportion to the fault severity. According to the mentioned observations, an accurate frequency pattern is specified for static eccentricity detection in three-phase LSPMSM.

Stochastic orbital migration of small bodies in Saturn's rings

Science.gov (United States)

Rein, H.; Papaloizou, J. C. B.

2010-12-01

Many small moonlets that create propeller structures have been found in Saturn's rings by the Cassini spacecraft. We study the dynamical evolution of such 20-50 m sized bodies, which are embedded in Saturn's rings. We estimate the importance of various interaction processes with the ring particles on the moonlet's eccentricity and semi-major axis analytically. For low ring surface densities, the main effects on the evolution of the eccentricity and the semi-major axis are found to be caused by collisions and the gravitational interaction with particles in the vicinity of the moonlet. For high surface densities, the gravitational interaction with self-gravity wakes becomes important. We also perform realistic three-dimensional, collisional N-body simulations with up to a quarter of a million particles. A new set of pseudo shear periodic boundary conditions is used, which reduces the computational costs by an order of magnitude compared to previous studies. Our analytic estimates are confirmed to within a factor of two. On short timescales the evolution is always dominated by stochastic effects caused by collisions and gravitational interaction with self-gravitating ring particles. These result in a random walk of the moonlet's semi-major axis. The eccentricity of the moonlet quickly reaches an equilibrium value owing to collisional damping. The average change in semi-major axis of the moonlet after 100 orbital periods is 10-100m. This translates to an offset in the azimuthal direction of several hundred kilometres. We expect that such a shift is easily observable. Two movies are only available in electronic form at http://www.aanda.org

Effect of eccentric exercise on the healing process of injured patellar tendon in rats

OpenAIRE

Nakamura, Kenichi; Kitaoka, Katsuhiko; Tomita, Katsuro

2008-01-01

Background. Earlier studies have reported positive results from eccentric training in patients with tendon disorders. The reasons for the beneficial clinical effects of eccentric training are not known. Vascularization followed by regression of the vasculature enhances the healing response of injured tendons. Eccentric exercise induces a more beneficial healing response than concentric exercise. Methods. Sixty rats with patellar tendon injuries were divided into three groups: nonexercise cont...

Eccentric exercise decreases maximal insulin action in humans

DEFF Research Database (Denmark)

Asp, Svend; Daugaard, J R; Kristiansen, S

1996-01-01

subjects participated in two euglycaemic clamps, performed in random order. One clamp was preceded 2 days earlier by one-legged eccentric exercise (post-eccentric exercise clamp (PEC)) and one was without the prior exercise (control clamp (CC)). 2. During PEC the maximal insulin-stimulated glucose uptake...... for all three clamp steps used (P maximal activity of glycogen synthase was identical in the two thighs for all clamp steps. 3. The glucose infusion rate (GIR......) necessary to maintain euglycaemia during maximal insulin stimulation was lower during PEC compared with CC (15.7%, 81.3 +/- 3.2 vs. 96.4 +/- 8.8 mumol kg-1 min-1, P maximal...

Therapeutic potential of eccentric exercises for age-related muscle atrophy

Directory of Open Access Journals (Sweden)

Jae-Young Lim

2016-09-01

Full Text Available Recent studies have focused on evidence-based interventions to prevent mobility decline and enhance physical performance in older adults. Several modalities, in addition to traditional strengthening programs, have been designed to manage age-related functional decline more effectively. In this study, we reviewed the current relevant literatures to assess the therapeutic potential of eccentric exercises for age-related muscle atrophy (sarcopenia. Age-related changes in human skeletal muscle, and their relationship with physical performance, are discussed with reference to in vitro physiologic and human biomechanics studies. An overview of issues relevant to sarcopenia is provided in the context of the recent consensus on the diagnosis and management of the condition. A decline in mobility among the aging population is closely linked with changes in the muscle force–velocity relationship. Interventions based specifically on increasing velocity and eccentric strength can improve function more effectively compared with traditional strengthening programs. Eccentric strengthening programs are introduced as a specific method for improving both muscle force and velocity. To be more effective, exercise interventions for older adults should focus on enhancing the muscle force–velocity relationship. Exercises that can be performed easily, and that utilize eccentric strength (which is relatively spared during the aging process, are needed to improve both muscle force and velocity.

Behaviour of Strengthened RC Frames with Eccentric Steel Braced Frames

Directory of Open Access Journals (Sweden)

Kamanli Mehmet

2017-01-01

Full Text Available After devastating earthquakes in recent years, strengthening of reinforced concrete buildings became an important research topic. Reinforced concrete buildings can be strengthened by steel braced frames. These steel braced frames may be made of concentrically or eccentrically indicated in Turkish Earthquake Code 2007. In this study pushover analysis of the 1/3 scaled 1 reinforced concrete frame and 1/3 scaled 4 strengthened reinforced concrete frames with internal eccentric steel braced frames were conducted by SAP2000 program. According to the results of the analyses conducted, load-displacement curves of the specimens were compared and evaluated. Adding eccentric steel braces to the bare frame decreased the story drift, and significantly increased strength, stiffness and energy dissipation capacity. In this strengthening method lateral load carrying capacity, stiffness and dissipated energy of the structure can be increased.

Antegrade Ureteral Stenting is a Good Alternative for the Retrograde Approach.

Science.gov (United States)

van der Meer, Rutger W; Weltings, Saskia; van Erkel, Arian R; Roshani, Hossain; Elzevier, Henk W; van Dijk, Lukas C; van Overhagen, Hans

2017-07-01

Double J (JJ) stents for treating obstructive ureteral pathology are generally inserted through a retrograde route with cystoscopic guidance. Antegrade percutaneous insertion using fluoroscopy can be performed alternatively but is less known. Indications, success rate and complications of antegrade ureteral stenting were evaluated. Data of consecutive patients in which antegrade ureteral stenting was performed were retrospectively analysed using the radiology information system and patient records. Patient characteristics, details of the antegrade JJ stent insertion procedure and registered complications were collected. Furthermore, it was investigated if prior to the antegrade procedure a retrograde attempt for JJ stent insertion was performed. Total 130 attempts for antegrade JJ stent insertion were performed in 100 patients. A percutaneous nephrostomy catheter had already been placed in the majority of kidneys (n = 109) for initial treatment of hydronephrosis. Most prevelant indication for a JJ stent was obstructive ureteral pathology due to malignancy (n = 63). A JJ stent was successfully inserted in 125 of 130 procedures. In 21 cases, previous retrograde ureteral stenting had failed but, subsequent antegrade ureteral stenting was successful. There were 8 procedure related complications; 6 infections, 1 false tract and 1 malposition. Antegrade percutaneous insertion of a JJ stent is a good alternative for retrograde insertion.

Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy for gingival carcinoma

Energy Technology Data Exchange (ETDEWEB)

Mukai, Y.; Hata, M.; Koike, I.; Inoue, T. [Yokohama City University Graduate School of Medicine, Department of Radiology, Kanazawa-ku, Yokohama, Kanagawa (Japan); Mitsudo, K.; Koizumi, T.; Oguri, S.; Kioi, M.; Tohnai, I. [Yokohama City University Graduate School of Medicine, Department of Oral and Maxillofacial Surgery, Yokohama, Kanagawa (Japan); Omura, M. [Shonankamakura General Hospital, Department of Radiation Oncology, Kamakura, Kanagawa (Japan)

2014-02-15

The aim of this study was to review the efficacy and toxicity of radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy in the treatment of gingival carcinoma. In all, 34 patients (21 men and 13 women) with squamous cell carcinoma of the gingiva underwent radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy. Treatment consisted of daily external irradiation and concurrent retrograde superselective intra-arterial infusion with cisplatin and docetaxel. A median total dose of 60 Gy in 30 fractions was delivered to tumors. Of the 34 patients, 29 (85 %) achieved a complete response (CR) and 5 had residual tumors. Of the 29 patients with a CR, 2 had local recurrences and 1 had distant metastasis 1-15 months after treatment. Twenty-six of the 36 patients had survived at a median follow-up time of 36 months (range 12-79 months); 4 died of cancer and 4 died of non-cancer-related causes. At both 3 and 5 years after treatment, the overall survival rates were 79 % and the cause-specific survival rates were 85 %. Osteoradionecrosis of the mandibular bone only developed in 1 patient after treatment. Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy was effective and safe in the treatment of gingival carcinoma. This treatment may be a promising curative and organ-preserving treatment option for gingival carcinoma. (orig.) [German] Das Ziel dieser Studie war die Ueberpruefung der Effizienz und Toxizitaet einer Strahlenbehandlung des Gingivakarzinoms mit gleichzeitiger retrograder, superselektiver intraarterieller Chemotherapie. Insgesamt 34 Patienten (21 Maenner und 13 Frauen) mit Zahnfleischplattenzellkarzinom erhielten eine Strahlenbehandlung mit gleichzeitiger retrograder, superselektiver intraarterieller Chemotherapie. Die Behandlung umfasste eine taegliche externe Bestrahlung mit gleichzeitiger retrograder, superselektiver intraarterieller Infusion von Cisplatin und

Retrograde Signals: Integrators of Interorganellar Communication and Orchestrators of Plant Development.

Science.gov (United States)

de Souza, Amancio; Wang, Jin-Zheng; Dehesh, Katayoon

2017-04-28

Interorganellar cooperation maintained via exquisitely controlled retrograde-signaling pathways is an evolutionary necessity for maintenance of cellular homeostasis. This signaling feature has therefore attracted much research attention aimed at improving understanding of the nature of these communication signals, how the signals are sensed, and ultimately the mechanism by which they integrate targeted processes that collectively culminate in organellar cooperativity. The answers to these questions will provide insight into how retrograde-signal-mediated regulatory mechanisms are recruited and which biological processes are targeted, and will advance our understanding of how organisms balance metabolic investments in growth against adaptation to environmental stress. This review summarizes the present understanding of the nature and the functional complexity of retrograde signals as integrators of interorganellar communication and orchestrators of plant development, and offers a perspective on the future of this critical and dynamic area of research.

Review of pump suction reducer selection: Eccentric or concentric reducers

OpenAIRE

Mahaffey, R M; van Vuuren, S J

2014-01-01

Eccentric reducers are traditionally recommended for the pump suction reducer fitting to allow for transportation of air through the fitting to the pump. The ability of a concentric reducer to provide an improved approach flow to the pump while still allowing air to be transported through the fitting is investigated. Computational fluid dynamics (CFD) were utilised to analyse six concentric and six eccentric reducer geometries at four different inlet velocities to determine the flow velocity ...

ORBITS AND MASSES OF THE SATELLITES OF THE DWARF PLANET HAUMEA (2003 EL61)

International Nuclear Information System (INIS)

Ragozzine, D.; Brown, M. E.

2009-01-01

Using precise relative astrometry from the Hubble Space Telescope and the W. M. Keck Telescope, we have determined the orbits and masses of the two dynamically interacting satellites of the dwarf planet (136108) Haumea, formerly 2003 EL61. The orbital parameters of Hi'iaka, the outer, brighter satellite, match well the previously derived orbit. On timescales longer than a few weeks, no Keplerian orbit is sufficient to describe the motion of the inner, fainter satellite Namaka. Using a fully interacting three-point-mass model, we have recovered the orbital parameters of both orbits and the mass of Haumea and Hi'iaka; Namaka's mass is marginally detected. The data are not sufficient to uniquely determine the gravitational quadrupole of the nonspherical primary (described by J 2 ). The nearly coplanar nature of the satellites, as well as an inferred density similar to water ice, strengthen the hypothesis that Haumea experienced a giant collision billions of years ago. The excited eccentricities and mutual inclination point to an intriguing tidal history of significant semimajor axis evolution through satellite mean-motion resonances. The orbital solution indicates that Namaka and Haumea are currently undergoing mutual events and that the mutual event season will last for next several years.

The Effects of Eccentric Contraction Duration on Muscle Strength, Power Production, Vertical Jump, and Soreness.

Science.gov (United States)

Mike, Jonathan N; Cole, Nathan; Herrera, Chris; VanDusseldorp, Trisha; Kravitz, Len; Kerksick, Chad M

2017-03-01

Mike, JN, Cole, N, Herrera, C, VanDusseldorp, T, Kravitz, L, and Kerksick, CM. The effects of eccentric contraction duration on muscle strength, power production, vertical jump, and soreness. J Strength Cond Res 31(3): 773-786, 2017-Previous research has investigated the effects of either eccentric-only training or comparing eccentric and concentric exercise on changes related to strength and power expression, but no research to date has investigated the impact of altering the duration of either the concentric or the eccentric component on these parameters. Therefore, the purpose of this study was to assess the duration of eccentric (i.e., 2-second, 4-second vs. 6-second) muscle contractions and their effect on muscle strength, power production, vertical jump, and soreness using a plate-loaded barbell Smith squat exercise. Thirty college-aged men (23 ± 3.5 years, 178 ± 6.8 cm, 82 ± 12 kg, and 11.6 ± 5.1% fat) with 3.0 ± 1.0 years of resistance training experience and training frequency of 4.3 ± 0.9 days per week were randomized and assigned to 1 of 3 eccentric training groups that incorporated different patterns of contraction. For every repetition, all 3 groups used 2-second concentric contractions and paused for 1 second between the concentric and eccentric phases. The control group (2S) used 2-second eccentric contractions, whereas the 4S group performed 4-second eccentric contractions and the 6S group performed 6-second eccentric contractions. All repetitions were completed using the barbell Smith squat exercise. All participants completed a 4-week training protocol that required them to complete 2 workouts per week using their prescribed contraction routine for 4 sets of 6 repetitions at an intensity of 80-85% one repetition maximum (1RM). For all performance data, significant group × time (G × T) interaction effects were found for average power production across all 3 sets of a squat jump protocol (p = 0.04) while vertical jump did not reach

Real-time visualization and quantification of retrograde cardioplegia delivery using near infrared fluorescent imaging.

Science.gov (United States)

Rangaraj, Aravind T; Ghanta, Ravi K; Umakanthan, Ramanan; Soltesz, Edward G; Laurence, Rita G; Fox, John; Cohn, Lawrence H; Bolman, R M; Frangioni, John V; Chen, Frederick Y

2008-01-01

Homogeneous delivery of cardioplegia is essential for myocardial protection during cardiac surgery. Presently, there exist no established methods to quantitatively assess cardioplegia distribution intraoperatively and determine when retrograde cardioplegia is required. In this study, we evaluate the feasibility of near infrared (NIR) imaging for real-time visualization of cardioplegia distribution in a porcine model. A portable, intraoperative, real-time NIR imaging system was utilized. NIR fluorescent cardioplegia solution was developed by incorporating indocyanine green (ICG) into crystalloid cardioplegia solution. Real-time NIR imaging was performed while the fluorescent cardioplegia solution was infused via the retrograde route in five ex vivo normal porcine hearts and in five ex vivo porcine hearts status post left anterior descending (LAD) coronary artery ligation. Horizontal cross-sections of the hearts were obtained at proximal, middle, and distal LAD levels. Videodensitometry was performed to quantify distribution of fluorophore content. The progressive distribution of cardioplegia was clearly visualized with NIR imaging. Complete visualization of retrograde distribution occurred within 4 minutes of infusion. Videodensitometry revealed retrograde cardioplegia, primarily distributed to the left ventricle (LV) and anterior septum. In hearts with LAD ligation, antegrade cardioplegia did not distribute to the anterior LV. This deficiency was compensated for with retrograde cardioplegia supplementation. Incorporation of ICG into cardioplegia allows real-time visualization of cardioplegia delivery via NIR imaging. This technology may prove useful in guiding intraoperative decisions pertaining to when retrograde cardioplegia is mandated.

Analysis of Periodic Orbits about the Triangular Solutions of the Restricted Sum-Jupiter and Earth-Moon Problem

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Sang-Young Park

1988-12-01

Full Text Available Using the numerical solution in the plane restricted problem of three bodies, about 490 periodic orbits are computed numerically around the L5 of Sun-Jupiter and about 1600 periodic orbits also be done around the L5 of Earth-Moon system. As period increase, the energy and the shape of periodic orbits increase around the L5 of Sun-Jupiter system. But, in Earth-Moon system, the complex shapes and dents appear around the L5 and periodic orbits intersect one another in the place where dents are shown. And there is a region that three different periodic orbits exist with the same period in this region. The regions can exist around the L5 of Sun-Jupiter system where periodic orbit can be unstable by perturbation of other force besides the gravitational force of Jupiter. These regions which is close to L5 are a ~5.12 AU and a ~5.29 AU. The Trojan asteroids that have a small eccentricity and inclination can not exist in this region.

Lifetime of a spacecraft around a synchronous system of asteroids using a dipole model

Science.gov (United States)

dos Santos, Leonardo Barbosa Torres; de Almeida Prado, Antonio F. Bertachini; Sanchez, Diogo Merguizo

2017-11-01

Space missions allow us to expand our knowledge about the origin of the solar system. It is believed that asteroids and comets preserve the physical characteristics from the time that the solar system was created. For this reason, there was an increase of missions to asteroids in the past few years. To send spacecraft to asteroids or comets is challenging, since these objects have their own characteristics in several aspects, such as size, shape, physical properties, etc., which are often only discovered after the approach and even after the landing of the spacecraft. These missions must be developed with sufficient flexibility to adjust to these parameters, which are better determined only when the spacecraft reaches the system. Therefore, conducting a dynamic investigation of a spacecraft around a multiple asteroid system offers an extremely rich environment. Extracting accurate information through analytical approaches is quite challenging and requires a significant number of restrictive assumptions. For this reason, a numerical approach to the dynamics of a spacecraft in the vicinity of a binary asteroid system is offered in this paper. In the present work, the equations of the Restricted Synchronous Four-Body Problem (RSFBP) are used to model a binary asteroid system. The main objective of this work is to construct grids of initial conditions, which relates semi-major axis and eccentricity, in order to quantify the lifetime of a spacecraft when released close to the less massive body of the binary system (modeled as a rotating mass dipole). We performed an analysis of the lifetime of the spacecraft considering several mass ratios of a binary system of asteroids and investigating the behavior of a spacecraft in the vicinity of this system. We analyze direct and retrograde orbits. This study investigated orbits that survive for at least 500 orbital periods of the system (which is approximately one year), then not colliding or escaping from the system during this

A UNIFIED FRAMEWORK FOR THE ORBITAL STRUCTURE OF BARS AND TRIAXIAL ELLIPSOIDS

Energy Technology Data Exchange (ETDEWEB)

Valluri, Monica; Abbott, Caleb [Department of Astronomy, University of Michigan, Ann Arbor, MI 48109 (United States); Shen, Juntai [Key Laboratory for Research in Galaxies and Cosmology, Shanghai Astronomical Observatory, Chinese Academy of Sciences, 80 Nandan Road, Shanghai 200030 (China); Debattista, Victor P., E-mail: mvalluri@umich.edu, E-mail: calebga@umich.edu, E-mail: jshen@shao.ac.cn, E-mail: vpdebattista@uclan.ac.uk [Jeremiah Horrocks Institute, University of Central Lancashire, Preston, PR1 2HE (United Kingdom)

2016-02-20

We examine a large random sample of orbits in two self-consistent simulations of N-body bars. Orbits in these bars are classified both visually and with a new automated orbit classification method based on frequency analysis. The well-known prograde x1 orbit family originates from the same parent orbit as the box orbits in stationary and rotating triaxial ellipsoids. However, only a small fraction of bar orbits (∼4%) have predominately prograde motion like their periodic parent orbit. Most bar orbits arising from the x1 orbit have little net angular momentum in the bar frame, making them equivalent to box orbits in rotating triaxial potentials. In these simulations a small fraction of bar orbits (∼7%) are long-axis tubes that behave exactly like those in triaxial ellipsoids: they are tipped about the intermediate axis owing to the Coriolis force, with the sense of tipping determined by the sign of their angular momentum about the long axis. No orbits parented by prograde periodic x2 orbits are found in the pure bar model, but a tiny population (∼2%) of short-axis tube orbits parented by retrograde x4 orbits are found. When a central point mass representing a supermassive black hole (SMBH) is grown adiabatically at the center of the bar, those orbits that lie in the immediate vicinity of the SMBH are transformed into precessing Keplerian orbits that belong to the same major families (short-axis tubes, long-axis tubes and boxes) occupying the bar at larger radii. During the growth of an SMBH, the inflow of mass and outward transport of angular momentum transform some x1 and long-axis tube orbits into prograde short-axis tubes. This study has important implications for future attempts to constrain the masses of SMBHs in barred galaxies using orbit-based methods like the Schwarzschild orbit superposition scheme and for understanding the observed features in barred galaxies.

Right retrograde brachial cerebral angiography with simultaneous compression of the left carotid artery

International Nuclear Information System (INIS)

Ericson, K.; Mosskin, M.

1981-01-01

Right retrograde brachial angiography with simultaneous compression of the left common carotid artery was performed in 12 patients, invariably resulting in filling of the right vertebral and the basilar artery. In all but one patient, the right carotid artery and its branches were also filled. Retrograde filling of the left internal carotid artery occurred in 8 patients. Furthermore, retrograde filling of the intracranial part of the left vertebral artery was obtained in 5 of 12 patients. A complete four-vessel cranial angiography was thus obtained in one third of the patients. The method may be considered as a safe and valuable adjunct to other angiographic techniques. (Auth.)

Electromyographic comparison of concentric and eccentric ...

African Journals Online (AJOL)

The study was conducted to compare the Electromyographic (EMG) activity variation of contractions (concentric and eccentric) during three different abdominal exercises (sit-up) exercises on rectus abdominal (upper and lower rectus). The sit-up exercises were: straight leg sit-up, bent leg sit-up and crunches. The EMG ...

Influence of Wheel Eccentricity on Vertical Vibration of Suspended Monorail Vehicle: Experiment and Simulation

Directory of Open Access Journals (Sweden)

Kaikai Lv

2017-01-01

Full Text Available This paper investigates the influence of wheel eccentricity on vertical vibration of suspended monorail vehicle based on experiment and simulation. Two sets of tests are conducted in the first Chinese suspended monorail, and the tested acceleration is analyzed and exhibited. A multibody dynamic model of the suspended monorail vehicle is established to simulate the vertical vibration of car body excited by wheel eccentricity. The results show that there are three factors which may cause an abnormal vibration considering the track and the vehicle system. The influence of wheel eccentricity on the car body vibration was firstly analyzed. Simulated acceleration of car body has a great accordance with test. The wheel eccentricity could excite the resonance of car body at the speed of 21 km/h, and the vertical acceleration would increase considerably. Decreasing the secondary stiffness can effectively reduce the vertical vibration caused by wheel eccentricity, especially at the resonant speed. In the secondary test, the peak of car body acceleration at speed of 20 km/h is not appearing when only renewing the wheels, and the acceleration is decreasing obviously at the domain frequency. It is further determined that the abnormal vibration is mainly caused by the wheel eccentricity.

HAMSTRING ARCHITECTURAL AND FUNCTIONAL ADAPTATIONS FOLLOWING LONG VS. SHORT MUSCLE LENGTH ECCENTRIC TRAINING

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Kenny Guex

2016-08-01

Full Text Available Most common preventive eccentric-based exercises, such as Nordic hamstring do not include any hip flexion. So, the elongation stress reached is lower than during the late swing phase of sprinting. The aim of this study was to assess the evolution of hamstring architectural (fascicle length and pennation angle and functional (concentric and eccentric optimum angles and concentric and eccentric peak torques parameters following a 3-week eccentric resistance program performed at long (LML versus short muscle length (SML. Both groups performed eight sessions of 3-5x8 slow maximal eccentric knee extensions on an isokinetic dynamometer: the SML group at 0° and the LML group at 80° of hip flexion. Architectural parameters were measured using ultrasound imaging and functional parameters using the isokinetic dynamometer. The fascicle length increased by 4.9% (p<0.01, medium effect size in the SML and by 9.3% (p<0.001, large effect size in the LML group. The pennation angle did not change (p=0.83 in the SML and tended to decrease by 0.7° (p=0.09, small effect size in the LML group. The concentric optimum angle tended to decrease by 8.8° (p=0.09, medium effect size in the SML and by 17.3° (p<0.01, large effect size in the LML group. The eccentric optimum angle did not change (p=0.19, small effect size in the SML and tended to decrease by 10.7° (p=0.06, medium effect size in the LML group. The concentric peak torque did not change in the SML (p=0.37 and the LML (p=0.23 groups, whereas eccentric peak torque increased by 12.9% (p<0.01, small effect size and 17.9% (p<0.001, small effect size in the SML and the LML group, respectively. No group-by-time interaction was found for any parameters. A correlation was found between the training-induced change in fascicle length and the change in concentric optimum angle (r=-0.57, p<0.01. These results suggest that performing eccentric exercises lead to several architectural and functional adaptations. However

Intra-tester Reliability and Construct Validity of a Hip Abductor Eccentric Strength Test.

Science.gov (United States)

Brindle, Richard A; Ebaugh, D David; Milner, Clare E

2017-11-15

Side-lying hip abductor strength tests are commonly used to evaluate muscle strength. In a 'break' test the tester applies sufficient force to lower the limb to the table while the patient resists. The peak force is postulated to occur while the leg is lowering, thus representing the participant's eccentric muscle strength. However, it is unclear whether peak force occurs before or after the leg begins to lower. To determine intra-rater reliability and construct validity of a hip abductor eccentric strength test. Intra-rater reliability and construct validity study. Twenty healthy adults (26 ±6 years; 1.66 ±0.06 m; 62.2 ±8.0 kg) made two visits to the laboratory at least one week apart. During the hip abductor eccentric strength test, a hand-held dynamometer recorded peak force and time to peak force and limb position was recorded via a motion capture system. Intra-rater reliability was determined using intra-class correlation (ICC), standard error of measurement (SEM), and minimal detectable difference (MDD). Construct validity was assessed by determining if peak force occurred after the start of the lowering phase using a one-sample t-test. The hip abductor eccentric strength test had substantial intra-rater reliability (ICC( 3,3 ) = 0.88; 95% confidence interval: 0.65-0.95), SEM of 0.9%BWh, and a MDD of 2.5%BWh. Construct validity was established as peak force occurred 2.1s (±0.6s; range 0.7s to 3.7s) after the start of the lowering phase of the test (p ≤ 0.001). The hip abductor eccentric strength test is a valid and reliable measure of eccentric muscle strength. This test may be used clinically to assess changes in eccentric muscle strength over time.

Formation of S-type planets in close binaries: scattering induced tidal capture of circumbinary planets

Science.gov (United States)

Gong, Yan-Xiang; Ji, Jianghui

2018-05-01

Although several S-type and P-type planets in binary systems were discovered in past years, S-type planets have not yet been found in close binaries with an orbital separation not more than 5 au. Recent studies suggest that S-type planets in close binaries may be detected through high-accuracy observations. However, nowadays planet formation theories imply that it is difficult for S-type planets in close binaries systems to form in situ. In this work, we extensively perform numerical simulations to explore scenarios of planet-planet scattering among circumbinary planets and subsequent tidal capture in various binary configurations, to examine whether the mechanism can play a part in producing such kind of planets. Our results show that this mechanism is robust. The maximum capture probability is ˜10%, which can be comparable to the tidal capture probability of hot Jupiters in single star systems. The capture probability is related to binary configurations, where a smaller eccentricity or a low mass ratio of the binary will lead to a larger probability of capture, and vice versa. Furthermore, we find that S-type planets with retrograde orbits can be naturally produced via capture process. These planets on retrograde orbits can help us distinguish in situ formation and post-capture origin for S-type planet in close binaries systems. The forthcoming missions (PLATO) will provide the opportunity and feasibility to detect such planets. Our work provides several suggestions for selecting target binaries in search for S-type planets in the near future.

The relationships of eccentric strength and power with dynamic balance in male footballers.

Science.gov (United States)

Booysen, Marc Jon; Gradidge, Philippe Jean-Luc; Watson, Estelle

2015-01-01

Unilateral balance is critical to kicking accuracy in football. In order to design interventions to improve dynamic balance, knowledge of the relationships between dynamic balance and specific neuromuscular factors such as eccentric strength and power is essential. Therefore, the aim was to determine the relationships of eccentric strength and power with dynamic balance in male footballers. The Y-balance test, eccentric isokinetic strength testing (knee extensors and flexors) and the countermovement jump were assessed in fifty male footballers (university (n = 27, mean age = 20.7 ± 1.84 years) and professional (n = 23, mean age = 23.0 ± 3.08 years). Spearman Rank Order correlations were used to determine the relationships of eccentric strength and power with dynamic balance. Multiple linear regression, adjusting for age, mass, stature, playing experience and competitive level was performed on significant relationships. Normalised reach score in the Y-balance test using the non-dominant leg for stance correlated with (1) eccentric strength of the non-dominant leg knee extensors in the university group (r = 0.50, P = 0.008) and (2) countermovement jump height in the university (r = 0.40, P = 0.04) and professional (r = 0.56, P = 0.006) football groups, respectively. No relationships were observed between eccentric strength (knee flexors) and normalised reach scores. Despite the addition of potential confounders, the relationship of power and dynamic balance was significant (r = 0.52, P power correlates moderately with dynamic balance on the non-dominant leg in male footballers.

SPIN-ORBIT ALIGNMENT FOR THE CIRCUMBINARY PLANET HOST KEPLER-16 A

International Nuclear Information System (INIS)

Winn, Joshua N.; Albrecht, Simon; Johnson, John Asher; Torres, Guillermo; Carter, Joshua A.; Ragozzine, Darin; Quinn, Samuel N.; Latham, David W.; Cochran, William D.; Marcy, Geoffrey W.; Howard, Andrew W.; Isaacson, Howard; Fischer, Debra; Doyle, Laurance; Welsh, William; Orosz, Jerome; Fabrycky, Daniel C.; Shporer, Avi; Howell, Steve B.; Prsa, Andrej

2011-01-01

Kepler-16 is an eccentric low-mass eclipsing binary with a circumbinary transiting planet. Here, we investigate the angular momentum of the primary star, based on Kepler photometry and Keck spectroscopy. The primary star's rotation period is 35.1 ± 1.0 days, and its projected obliquity with respect to the stellar binary orbit is 1. 0 6 ± 2. 0 4. Therefore, the three largest sources of angular momentum-the stellar orbit, the planetary orbit, and the primary's rotation-are all closely aligned. This finding supports a formation scenario involving accretion from a single disk. Alternatively, tides may have realigned the stars despite their relatively wide separation (0.2 AU), a hypothesis that is supported by the agreement between the measured rotation period and the 'pseudosynchronous' period of tidal evolution theory. The rotation period, chromospheric activity level, and fractional light variations suggest a main-sequence age of 2-4 Gyr. Evolutionary models of low-mass stars can match the observed masses and radii of the primary and secondary stars to within about 3%.

Effect of eccentricity on searches for gravitational waves from coalescing compact binaries in ground-based detectors

International Nuclear Information System (INIS)

Brown, Duncan A.; Zimmerman, Peter J.

2010-01-01

Inspiralling compact binaries are expected to circularize before their gravitational-wave signals reach the sensitive frequency band of ground-based detectors. Current searches for gravitational waves from compact binaries using the LIGO and Virgo detectors therefore use circular templates to construct matched filters. Binary formation models have been proposed which suggest that some systems detectable by the LIGO-Virgo network may have non-negligible eccentricity. We investigate the ability of the restricted 3.5 post-Newtonian order TaylorF2 template bank, used by LIGO and Virgo to search for gravitational waves from compact binaries with masses M≤35M · , to detect binaries with nonzero eccentricity. We model the gravitational waves from eccentric binaries using the x-model post-Newtonian formalism proposed by Hinder et al.[I. Hinder, F. Hermann, P. Laguna, and D. Shoemaker, arXiv:0806.1037v1]. We find that small residual eccentricities (e 0 · · . For eccentricities e 0 > or approx. 0.1, the loss in matched filter signal-to-noise ratio due to eccentricity can be significant and so templates which include eccentric effects will be required to perform optimal searches for such systems.

The Bearing Capacity of Strip Footings in Cohesionless Soil Subject to Eccentric and Inclined Loads

DEFF Research Database (Denmark)

Krabbenhøft, Sven; Damkilde, Lars; Krabbenhøft, Kristian

2014-01-01

Lower bound calculations based on the finite element method is used to determine the bearing capacity of a strip foundation subjected to an inclined, eccentric load on cohesionless soil with varying surcharges and with friction angles 25, 30 and 35°. The soil is assumed perfectly plastic following...... the Mohr-Coulomb failure criterion. The results are reported as graphs showing the bearing capacity as a function of the friction angle, the eccentricity, inclination and the surcharge. The results have been compared with the Eurocode 7 and for smaller eccentricities, except in the case of no surcharge......, the lower bound values are the greater, the discrepancy increasing with growing surcharge. Positive load inclinations has a negative effect for smaller eccentricities but may have a beneficial effect on the bearing capacity for greater eccentricities. Negative load inclinations have the opposite effect...

Profound loss of general knowledge in retrograde amnesia: Evidence from an amnesic artist

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Emma eGregory

2014-05-01

Full Text Available Studies of retrograde amnesia have focused on autobiographical memory, with fewer studies examining how non-autobiographical memory is affected. Those that have done so have focused primarily on memory for famous people and public events—relatively limited aspects of memory that are tied to learning during specific times of life and do not deeply tap into the rich and extensive knowledge structures that are developed over a lifetime. To assess whether retrograde amnesia can also cause impairments to other forms of general world knowledge, we explored losses across a broad range of knowledge domains in a newly-identified amnesic. LSJ is a professional artist, amateur musician and history buff with extensive bilateral medial temporal and left anterior temporal damage. We examined LSJ's knowledge across a range of everyday domains (e.g., sports and domains for which she had premorbid expertise (e.g., famous paintings. Across all domains tested, LSJ showed losses of knowledge at a level of breadth and depth never before documented in retrograde amnesia. These results show that retrograde amnesia can involve broad and deep deficits across a range of general world knowledge domains. Thus, losses that have already been well-documented (famous people and public events may severely underestimate the nature of human knowledge impairment that can occur in retrograde amnesia.

Greater Strength Gains after Training with Accentuated Eccentric than Traditional Isoinertial Loads in Already Strength-Trained Men

Science.gov (United States)

Walker, Simon; Blazevich, Anthony J.; Haff, G. Gregory; Tufano, James J.; Newton, Robert U.; Häkkinen, Keijo

2016-01-01

As training experience increases it becomes more challenging to induce further neuromuscular adaptation. Consequently, strength trainers seek alternative training methods in order to further increase strength and muscle mass. One method is to utilize accentuated eccentric loading, which applies a greater external load during the eccentric phase of the lift as compared to the concentric phase. Based upon this practice, the purpose of this study was to determine the effects of 10 weeks of accentuated eccentric loading vs. traditional isoinertial resistance training in strength-trained men. Young (22 ± 3 years, 177 ± 6 cm, 76 ± 10 kg, n = 28) strength-trained men (2.6 ± 2.2 years experience) were allocated to concentric-eccentric resistance training in the form of accentuated eccentric load (eccentric load = concentric load + 40%) or traditional resistance training, while the control group continued their normal unsupervised training program. Both intervention groups performed three sets of 6-RM (session 1) and three sets of 10-RM (session 2) bilateral leg press and unilateral knee extension exercises per week. Maximum force production was measured by unilateral isometric (110° knee angle) and isokinetic (concentric and eccentric 30°.s−1) knee extension tests, and work capacity was measured by a knee extension repetition-to-failure test. Muscle mass was assessed using panoramic ultrasonography and dual-energy x-ray absorptiometry. Surface electromyogram amplitude normalized to maximum M-wave and the twitch interpolation technique were used to examine maximal muscle activation. After training, maximum isometric torque increased significantly more in the accentuated eccentric load group than control (18 ± 10 vs. 1 ± 5%, p < 0.01), which was accompanied by an increase in voluntary activation (3.5 ± 5%, p < 0.05). Isokinetic eccentric torque increased significantly after accentuated eccentric load training only (10 ± 9%, p < 0.05), whereas concentric torque

Optical properties of an elliptic quantum ring: Eccentricity and electric field effects

Science.gov (United States)

Bejan, Doina; Stan, Cristina; Niculescu, Ecaterina C.

2018-04-01

We have theoretically studied the electronic and optical properties of a GaAs/AlGaAs elliptic quantum ring under in-plane electric field. The effects of an eccentric internal barrier -placed along the electric field direction, chosen as x-axis- and incident light polarization are particularly taken into account. The one-electron energy spectrum and wave functions are found using the adiabatic approximation and the finite element method within the effective-mass model. We show that it is possible to repair the structural distortion by applying an appropriate in-plane electric field, and the compensation is almost complete for all electronic states under study. For both concentric and eccentric quantum ring the intraband optical properties are very sensitive to the electric field and probe laser polarization. As expected, in the systems with eccentricity distortions the energy spectrum, as well as the optical response, strongly depends on the direction of the externally applied electric field, an effect that can be used as a signature of ring eccentricity. We demonstrated the possibility of generating second harmonic response at double resonance condition for incident light polarized along the x-axis if the electric field or/and eccentric barrier break the inversion symmetry. Also, strong third harmonic signal can be generated at triple resonance condition for a specific interval of electric field values when using y-polarized light.

Patellar tendon load in different types of eccentric squats.

Science.gov (United States)

Frohm, A; Halvorsen, K; Thorstensson, A

2007-07-01

Differences in mechanical loading of the patellar tendon have been suggested as a reason for varying effects in rehabilitation of patellar tendinopathy using different eccentric squat exercises and devices. The aim was to characterize the magnitude and pattern of mechanical load at the knee and on the patellar tendon during four types of eccentric squat. Subjects performed squats with a submaximal free weight and with maximal effort in a device for eccentric overloading (Bromsman), on a decline board and horizontal surface. Kinematics was recorded with a motion-capture system, reaction forces with force plates, and electromyography from three leg muscles with surface electrodes. Inverse dynamics was used to calculate knee joint kinetics. Eccentric work, mean and peak patellar tendon force, and angle at peak force were greater (25-30%) for squats on decline board compared to horizontal surface with free weight, but not in Bromsman. Higher knee load forces (60-80%), but not work, were observed with Bromsman than free weight. Angular excursions at the knee and ankle were larger with decline board, particularly with free weight, and smaller in Bromsman than with free weight. Mean electromyography was greater on a decline board for gastrocnemius (13%) and vastus medialis (6%) with free weight, but in Bromsman only for gastrocnemius (7%). The results demonstrated clear differences in the biomechanical loading on the knee during different squat exercises. Quantification of such differences provides information that could be used to explain differences in rehabilitation effects as well as in designing more optimal rehabilitation exercises for patellar tendinopathy.

Synchronous Retrograde and Micturating Cysto Urethrography A ...

African Journals Online (AJOL)

Background: Retrograde Urethrography (RUG) combined with Micturating cystourethrography (MCUG) is imaging method of choice for studying the urethra and its 1-9 abnormalities . Though there are many modern imaging modalities that are also useful but these are not available in most developing countries. Even the ...

Retrograde prostatic urethroplasty with a balloon catheter

International Nuclear Information System (INIS)

Castaneda, F.; Reddy, P.; Hulbert, J.; Letourneau, J.G.; Hunter, D.W.; Castaneda-Zuniga, W.R.; Amplatz, K.

1987-01-01

Twenty-five patients with prostatism and documented BPH who were candidates for transurethral resection of the prostate were dilated for 10 minutes with 25-mm urethroplasty balloons using a retrograde transurethral approach. The procedure was performed under local anesthesia using 2% viscous lidocaine on an outpatient basis. A mild discomfort was experienced by all patients with a moderate urgency sensation. Mild transient hematuria was present in all, which cleared in 4 to 6 hours. Dysuria usually lasted for 72 hours. Significant improvement has been seen in the relief of symptoms in patients without middle-lobe hypertrophy as documented by uroflow studies, voiding cystourethrograms, and retrograde urethrograms. In patients with middle-lobe hypertrophy, moderate improvement in uroflow studies was observed, which correlated well with symptomatic improvement. Rectal US and MR studies have shown no evidence of intraprostatic or periprostatic abnormalities. No complications have been encountered so far. The longest current follow-up is 20 months, with a mean of 10 months

Retrograde flow in the dural sinuses detected by three-dimensional time-of-flight MR angiography

International Nuclear Information System (INIS)

Uchino, Akira; Nomiyama, Keita; Takase, Yukinori; Nakazono, Takahiko; Tominaga, Yukiko; Imaizumi, Takeshi; Kudo, Sho

2007-01-01

Retrograde flow in the left dural sinuses is sometimes detected by three-dimensional time-of-flight (3D-TOF) magnetic resonance (MR) angiography. The purpose of this study was to evaluate the incidence of this phenomenon and its characteristic features on 3D-TOF MR angiograms. We retrospectively reviewed cranial MR angiography images of 1,078 patients examined at our institution. All images were obtained by the 3D-TOF technique with one of two 1.5-T scanners. Maximum intensity projection (MIP) images in the horizontal rotation view were displayed stereoscopically. We reviewed the source images, inferosuperior MIP images, and horizontal MIP images and identified retrograde flow in the dural sinuses. We found retrograde flow in the dural sinuses of 67 patients on the source images from 3D-TOF MR angiography; the incidence was 6.2%. In 47 of the 67 patients, retrograde flow was identified in the left inferior petrosal sinus, in 13, it was seen in the left sigmoid sinus, and in 6, it was seen in the left inferior petrosal and left sigmoid sinuses. The remaining patient had retrograde flow in the left inferior petrosal and left and right sigmoid sinuses. The mean age of the patients with retrograde flow was slightly greater than that of the patients without this phenomenon (70 years vs 63 years). Retrograde flow in the dural sinuses frequently occurs on the left side in middle-aged and elderly patients during 3D-TOF MR angiography performed with the patient in the supine position. This phenomenon should not be misdiagnosed as a dural arteriovenous fistula. (orig.)

Transport According to GARP: Receiving Retrograde Cargo at the Trans-Golgi Network

Science.gov (United States)

Bonifacino, Juan S.; Hierro, Aitor

2010-01-01

Tethering factors are large protein complexes that capture transport vesicles and enable their fusion with acceptor organelles at different stages of the endomembrane system. Recent studies have shed new light on the structure and function of a heterotetrameric tethering factor named Golgi-associated retrograde protein (GARP), which promotes fusion of endosome-derived, retrograde transport carriers to the trans-Golgi network (TGN). X-ray crystallography of the Vps53 and Vps54 subunits of GARP has revealed that this complex is structurally related to other tethering factors such as the exocyst, COG and Dsl1, indicating that they all might work by a similar mechanism. Loss of GARP function compromises the growth, fertility and/or viability of the defective organisms, underscoring the essential nature of GARP-mediated retrograde transport. PMID:21183348

Biomechanical Strength of Retrograde Fixation in Proximal Third Scaphoid Fractures.

Science.gov (United States)

Daly, Charles A; Boden, Allison L; Hutton, William C; Gottschalk, Michael B

2018-04-01

Current techniques for fixation of proximal pole scaphoid fractures utilize antegrade fixation via a dorsal approach endangering the delicate vascular supply of the dorsal scaphoid. Volar and dorsal approaches demonstrate equivalent clinical outcomes in scaphoid wrist fractures, but no study has evaluated the biomechanical strength for fractures of the proximal pole. This study compares biomechanical strength of antegrade and retrograde fixation for fractures of the proximal pole of the scaphoid. A simulated proximal pole scaphoid fracture was produced in 22 matched cadaveric scaphoids, which were then assigned randomly to either antegrade or retrograde fixation with a cannulated headless compression screw. Cyclic loading and load to failure testing were performed and screw length, number of cycles, and maximum load sustained were recorded. There were no significant differences in average screw length (25.5 mm vs 25.6 mm, P = .934), average number of cyclic loading cycles (3738 vs 3847, P = .552), average load to failure (348 N vs 371 N, P = .357), and number of catastrophic failures observed between the antegrade and retrograde fixation groups (3 in each). Practical equivalence between the 2 groups was calculated and the 2 groups were demonstrated to be practically equivalent (upper threshold P = .010). For this model of proximal pole scaphoid wrist fractures, antegrade and retrograde screw configuration have been proven to be equivalent in terms of biomechanical strength. With further clinical study, we hope surgeons will be able to make their decision for fixation technique based on approaches to bone grafting, concern for tenuous blood supply, and surgeon preference without fear of poor biomechanical properties.

Management of Endovascular Aortic Aneurysm Complications via Retrograde Catheterization Through the Distal Stent-Graft Landing Zone.

Science.gov (United States)

Zhang, Xicheng; Sun, Yuan; Chen, Zhaolei; Jing, Yuanhu; Xu, Miao

2017-08-01

A retrograde technique through the gap between the distal stent landing zone and the iliac artery wall has been applied to treat type II endoleak after endovascular aortic aneurysm repair (EVAR). In this study, we tried to investigate its efficacy in the management of type III endoleak and intraoperative accidental events. We reported 2 complications of EVAR that were difficult to treat with conventional methods. One patient had a sustained type III endoleak after EVAR, and the right renal artery was accidentally sealed by a graft stent in the other patient during the operation. Both complications were managed by the retrograde technique from the distal stent landing zone. In the first case, the endoleak was easily embolized by the retrograde catheterization technique, and in the second case, a stent was implanted in the right renal artery using the retrograde technique to restore blood flow. In some EVAR cases, the technique of retrograde catheterization through the distal stent-graft landing zone is feasible, safe, and easy to perform.

Retrograde CTO-PCI of Native Coronary Arteries Via Left Internal Mammary Artery Grafts: Insights From a Multicenter U.S. Registry.

Science.gov (United States)

Tajti, Peter; Karatasakis, Aris; Karmpaliotis, Dimitri; Alaswad, Khaldoon; Jaffer, Farouc A; Yeh, Robert W; Patel, Mitul; Mahmud, Ehtisham; Choi, James W; Doing, Anthony H; Toma, Catalin; Uretsky, Barry; Garcia, Santiago; Moses, Jeffrey W; Parikh, Manish; Kirtane, Ajay; Ali, Ziad A; Hatem, Raja; Karacsonyi, Judit; Danek, Barbara A; Rangan, Bavana V; Banerjee, Subhash; Ungi, Imre; Brilakis, Emmanouil S

2018-03-01

Retrograde percutaneous coronary intervention (PCI) of native coronary artery chronic total occlusion (CTO) via left internal mammary artery (LIMA) graft has received limited study. We compared the clinical and procedural characteristics and outcomes of retrograde CTO-PCI through LIMA grafts vs other conduits in a contemporary multicenter CTO registry. The LIMA was used as the collateral channel in 20 of 990 retrograde CTO-PCIs (2.02%) performed at 18 United States centers. The mean age of the study patients was 69 ± 7 years and 95% were men. The most common CTO target vessel was the right coronary artery (55%). The mean J-CTO score in the LIMA group was high (3.45 ± 0.76). The technical success rates were 70% for retrograde PCI via LIMA graft vs 81.05% for retrograde via other conduits (P=.25), while procedural success rates were 70% for retrograde PCI via LIMA graft and 78.19% for retrograde via other conduits (P=.41). The incidence of major in-hospital complications was also similar between the LIMA and non-LIMA retrograde groups (5% vs 6%; P>.99). Use of guide-catheter extensions (40% vs 28%; P=.22), intravascular ultrasound (45% vs 31%; P=.20), and left ventricular assist devices (24% vs 10%; P=.08) was numerically higher in retrograde CTO-PCIs via LIMA grafts. Retrograde CTO-PCI is infrequently performed via LIMA grafts and is associated with similar success and major in-hospital complication rates as retrograde CTO-PCI performed via other conduits.

Muscle fascicle behavior during eccentric cycling and its relation to muscle soreness.

Science.gov (United States)

Peñailillo, Luis; Blazevich, Anthony J; Nosaka, Kazunori

2015-04-01

A single bout of eccentric exercise confers a protective effect against muscle damage and soreness in subsequent eccentric exercise bouts, but the mechanisms underpinning this effect are unclear. This study compared vastus lateralis (VL) muscle-tendon behavior between two eccentric cycling bouts to test the hypothesis that muscle-tendon behavior would be different between bouts and would be associated with the protective effect. Eleven untrained men (27.1 ± 7.0 yr) performed two bouts of eccentric cycling (ECC1 and ECC2) separated by 2 wk for 10 min at 65% of maximal concentric workload (191.9 ± 44.2 W) each. Muscle soreness (by visual analog scale) and maximal voluntary isometric contraction (MVC) torque of the knee extensors were assessed before and 1-2 d after exercise. Using ultrasonography, VL fascicle length and angle changes during cycling were assessed, and tendinous tissue (TT) length changes were estimated. VL EMG amplitude, crank torque, and knee joint angles were measured during cycling. Soreness was greater (P tendon behavior may be an important mechanism underpinning the protective effect.

Impact of Emulsifiers Addition on the Retrogradation of Rice Gels during Low-Temperature Storage

Directory of Open Access Journals (Sweden)

Zhe Yang

2017-01-01

Full Text Available Rice and its products are widely consumed in Asian countries; however, starch retrogradation decreases the quality and shortens the shelf-life of rice foods particularly at low temperature. In this study sucrose ester (SE, glycerol monostearate (GMS, and sodium stearoyl lactylate (SSL were added to rice flour and corresponding rice gels. Then, gelatinization properties, retrogradation characteristics, texture, and water content of these rice gels were investigated at 4°C and −20°C storage, respectively. The results demonstrated that the rice gels with 0.2% GMS had the lowest retrogradation index (ΔHr/ΔHg (11.84% and hardness (1359 g at 4°C for a 10 d period, which was significantly lower in comparison to control and the other two emulsifiers (P<0.05. Adhesiveness and water content were increased compared to the other samples. Furthermore, the retrogradation of rice gels stored at 4°C was comparatively rapid compared to gels stored at −20°C. Gel samples stored at −20°C were still acceptable for more than 15 days. Thus it was revealed that GMS has the potential to retard starch retrogradation and produce high-quality rice products in preservation.

Eccentric Torque-Producing Capacity is Influenced by Muscle Length in Older Healthy Adults.

Science.gov (United States)

Melo, Ruth C; Takahashi, Anielle C M; Quitério, Robison J; Salvini, Tânia F; Catai, Aparecida M

2016-01-01

Considering the importance of muscle strength to functional capacity in the elderly, the study investigated the effects of age on isokinetic performance and torque production as a function of muscle length. Eleven younger (24.2 ± 2.9 years) and 16 older men (62.7 ± 2.5 years) were subjected to concentric and eccentric isokinetic knee extension/flexion at 60 and 120° · s(-1) through a functional range of motion. The older group presented lower peak torque (in newton-meters) than the young group for both isokinetic contraction types (age effect, p torque deficits in the older group were near 30 and 29% for concentric and eccentric contraction, respectively. Concentric peak torque was lower at 120° · s(-1) than at 60° · s(-1) for both groups (angular velocity effect, p torque was the only exercise tested that showed an interaction effect between age and muscle length (p torque responses to the muscle length between groups. Compared with the young group, the eccentric knee extension torque was 22-56% lower in the older group, with the deficits being lower in the shortened muscle length (22-27%) and higher (33-56%) in the stretched muscle length. In older men, the production of eccentric knee strength seems to be dependent on the muscle length. At more stretched positions, older subjects lose the capacity to generate eccentric knee extension torque. More studies are needed to assess the mechanisms involved in eccentric strength preservation with aging and its relationship with muscle length.

The effect of eccentric and concentric calf muscle training on Achilles tendon stiffness.

Science.gov (United States)

Morrissey, Dylan; Roskilly, Anna; Twycross-Lewis, Richard; Isinkaye, Tomide; Screen, Hazel; Woledge, Roger; Bader, Dan

2011-03-01

To compare in vivo effects of eccentric and concentric calf muscle training on Achilles tendon stiffness, in subjects without tendinopathy. Thirty-eight recreational athletes completed 6 weeks eccentric (6 males, 13 females, 21.6  ±  2.2 years) or concentric training (8 males, 11 females, 21.1  ±  2.0 years). Achilles tendon stiffness, tendon modulus and single-leg jump height were measured before and after intervention. Exercise adherence was recorded using a diary. All data are reported as mean  ±  SD. Groups were matched for height and weight but the eccentric training group were more active at baseline (P Tendon stiffness was higher in the eccentrically trained group at baseline compared to the concentrically trained group (20.9  ±  7.3 N/mm v 13.38  ±  4.66 N/mm; P = 0.001) and decreased significantly after eccentric training (to 17.2 ( ±  5.9) N/mm (P = 0.035)). There was no stiffness change in the concentric group (P = 0.405). Stiffness modulus showed similar changes to stiffness. An inverse correlation was found between initial, and subsequent, reduction in stiffness (r = -0.66). Jump height did not change and no correlation between stiffness change and adherence was observed in either group (r = 0.01). Six weeks of eccentric training can alter Achilles tendon stiffness while a matched concentric programme shows no similar effects. Studies in patients with Achilles tendinopathy are warranted.

The Effect of Taurine on the Recovery from Eccentric Exercise-Induced Muscle Damage in Males

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Yanita McLeay

2017-10-01

Full Text Available Eccentric exercise is known to bring about microstructural damage to muscle, initiating an inflammatory cascade involving various reactive oxygen species. This, in turn, can significantly impair physical performance over subsequent days. Taurine, a powerful endogenous antioxidant, has previously been shown to have a beneficial effect on muscle damage markers and recovery when taken for a few days to several weeks prior to eccentric exercise. However, to date no studies have looked at the effects of supplementing over the days following eccentric exercise on performance recovery. Thus, this study aimed to determine whether supplementing with taurine over three days following eccentric exercise attenuated the rise in serum creatine kinase and improved performance recovery in males. In a blinded, randomized, crossover design, ten recreationally-fit male participants completed 60 eccentric contractions of the biceps brachii muscle at maximal effort. Following this, participants were supplemented with 0.1 g∙kg−1 body weight∙day−1 of either taurine or rice flour in capsules. Over the next three mornings participants underwent blood tests for the analysis of the muscle damage marker creatine kinase and carried out performance measures on the isokinetic dynamometer. They also continued to consume the capsules in the morning and evening. The entire protocol was repeated two weeks later on the alternate arm and supplement. Significant decreases were seen in all performance measures from pre- to 24-h post-eccentric exercise (p < 0.001 for both taurine and placebo, indicating the attainment of muscle damage. Significant treatment effects were observed only for peak eccentric torque (p < 0.05. No significant time × treatment effects were observed (all p > 0.05. Serum creatine kinase levels did not significantly differ over time for either treatments, nor between treatments (p > 0.05. These findings suggest that taurine supplementation taken twice

Titan Crossing a 5:1 MMR with Iapetus : Constraining the Tidal Recession of Titan and Giving an Explanation for Lapetus' Current Orbit

Science.gov (United States)

POLYCARPE, William; Lainey, Valery; Vienne, Alain; Noyelles, Benoît; Saillenfest, Melaine; Rambaux, Nicolas

2018-04-01

Iapetus orbits Saturn with an orbtial eccentricity of 3% and possesses an constant tilt to its local Laplace plane of around 7°, both elements are today poorly explained. The objective of the this work is to investigate if these orbtial characteristics may be explained in the frame of rapid tidal migration in the saturnian system [Lainey et al., 2012, 2017] [Fuller et al. 2016]. We present several sets of numerical simulations of a past 5:1 mean motion resonance crossing between Titan and Iapetus. Iapetus was placed initially on its local Laplace plane with a circular orbit. Simulations show that the outcomes of this resonance are very dependent on the migration speed of Titan, and therefore on the effective quality factor Q of Saturn. Iapetus will generally be ejected of the system due to this resonance when the migration is too slow, typically Q higher than 1500. Lower values allow Iapetus to survive with an eccentricity of a few percent, consistent with today's value. This resonance would also act on the inclination and can bring the tilt up to several degrees, and even reach 7° and more on rare occasions. It seems, in general, that the current value of the eccentricity can be easily explained by this resonance. On the other hand the tilt is more difficult to obtain for fast tidal migration (Q lower than 20), but high values are possible for medium migration rate (typically Q between 200 and 1500).

Irrelevant, Incidental and Core Features in the Retrograde Amnesia Associated with Korsakoff’s Psychosis: A Review

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P. R. Meudell

1992-01-01

Full Text Available A brief review of the literature on retrograde amnesia in Korsakoff's syndrome is presented. Various explanations of the phenomenon are discussed including the notions that it results from the effects of “state-dependency”, that it occurs as a result of a progressive learning problem and that it arises through a failure in contextual processing. None of these hypotheses can satisfactorily account for the length and temporal gradient of alcoholic amnesics retrograde amnesia. Although some evidence points towards the hypothesis that anterograde and retrograde amnesia might result from separate and independent impairments, this view is presently unproven and leaves open what causes the form and duration of Korsakoffs retrograde amnesia.

Astrometric detectability of systems with unseen companions: effects of the Earth orbital motion

Science.gov (United States)

Butkevich, Alexey G.

2018-06-01

The astrometric detection of an unseen companion is based on an analysis of the apparent motion of its host star around the system's barycentre. Systems with an orbital period close to 1 yr may escape detection if the orbital motion of their host stars is observationally indistinguishable from the effects of parallax. Additionally, an astrometric solution may produce a biased parallax estimation for such systems. We examine the effects of the orbital motion of the Earth on astrometric detectability in terms of a correlation between the Earth's orbital position and the position of the star relative to its system barycentre. The χ2 statistic for parallax estimation is calculated analytically, leading to expressions that relate the decrease in detectability and accompanying parallax bias to the position correlation function. The impact of the Earth's motion critically depends on the exoplanet's orbital period, diminishing rapidly as the period deviates from 1 yr. Selection effects against 1-yr-period systems is, therefore, expected. Statistical estimation shows that the corresponding loss of sensitivity results in a typical 10 per cent increase in the detection threshold. Consideration of eccentric orbits shows that the Earth's motion has no effect on detectability for e≳ 0.5. The dependence of the detectability on other parameters, such as orbital phases and inclination of the orbital plane to the ecliptic, are smooth and monotonic because they are described by simple trigonometric functions.

Psychogenic amnesia: syndromes, outcome, and patterns of retrograde amnesia.

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Harrison, Neil A; Johnston, Kate; Corno, Federica; Casey, Sarah J; Friedner, Kimberley; Humphreys, Kate; Jaldow, Eli J; Pitkanen, Mervi; Kopelman, Michael D

2017-09-01

There are very few case series of patients with acute psychogenic memory loss (also known as dissociative/functional amnesia), and still fewer studies of outcome, or comparisons with neurological memory-disordered patients. Consequently, the literature on psychogenic amnesia is somewhat fragmented and offers little prognostic value for individual patients. In the present study, we reviewed the case records and neuropsychological findings in 53 psychogenic amnesia cases (ratio of 3:1, males:females), in comparison with 21 consecutively recruited neurological memory-disordered patients and 14 healthy control subjects. In particular, we examined the pattern of retrograde amnesia on an assessment of autobiographical memory (the Autobiographical Memory Interview). We found that our patients with psychogenic memory loss fell into four distinct groups, which we categorized as: (i) fugue state; (ii) fugue-to-focal retrograde amnesia; (iii) psychogenic focal retrograde amnesia following a minor neurological episode; and (iv) patients with gaps in their memories. While neurological cases were characterized by relevant neurological symptoms, a history of a past head injury was actually more common in our psychogenic cases (P = 0.012), perhaps reflecting a 'learning episode' predisposing to later psychological amnesia. As anticipated, loss of the sense of personal identity was confined to the psychogenic group. However, clinical depression, family/relationship problems, financial/employment problems, and failure to recognize the family were also statistically more common in that group. The pattern of autobiographical memory loss differed between the psychogenic groups: fugue cases showed a severe and uniform loss of memories for both facts and events across all time periods, whereas the two focal retrograde amnesia groups showed a 'reversed' temporal gradient with relative sparing of recent memories. After 3-6 months, the fugue patients had improved to normal scores for facts

An exact solution for orbit view-periods from a station on a tri-axial ellipsoidal planet

Science.gov (United States)

Tang, C. C. H.

1986-01-01

This paper presents the concise exact solution for predicting view-periods to be observed from a masked or unmasked tracking station on a tri-axial ellipsoidal surface. The new exact approach expresses the azimuth and elevation angles of a spacecraft in terms of the station-centered geodetic topocentric coordinates in an elegantly concise manner. A simple and efficient algorithm is developed to avoid costly repetitive computations in searching for neighborhoods near the rise and set times of each satellite orbit for each station. Only one search for each orbit is necessary for each station. Sample results indicate that the use of an assumed spherical earth instead of an 'actual' tri-axial ellipsoidal earth could introduce an error up to a few minutes in a view-period prediction for circular orbits of low or medium altitude. For an elliptical orbit of high eccentricity and long period, the maximum error could be even larger. The analytic treatment and the efficient algorithm are designed for geocentric orbits, but they should be applicable to interplanetary trajectories by an appropriate coordinates transformation at each view-period calculation. This analysis can be accomplished only by not using the classical orbital elements.

An exact solution for orbit view-periods from a station on a tri-axial ellipsoidal planet

Science.gov (United States)

Tang, C. C. H.

1986-08-01

This paper presents the concise exact solution for predicting view-periods to be observed from a masked or unmasked tracking station on a tri-axial ellipsoidal surface. The new exact approach expresses the azimuth and elevation angles of a spacecraft in terms of the station-centered geodetic topocentric coordinates in an elegantly concise manner. A simple and efficient algorithm is developed to avoid costly repetitive computations in searching for neighborhoods near the rise and set times of each satellite orbit for each station. Only one search for each orbit is necessary for each station. Sample results indicate that the use of an assumed spherical earth instead of an 'actual' tri-axial ellipsoidal earth could introduce an error up to a few minutes in a view-period prediction for circular orbits of low or medium altitude. For an elliptical orbit of high eccentricity and long period, the maximum error could be even larger. The analytic treatment and the efficient algorithm are designed for geocentric orbits, but they should be applicable to interplanetary trajectories by an appropriate coordinates transformation at each view-period calculation. This analysis can be accomplished only by not using the classical orbital elements.

Reconsidering the nature and mode of action of metabolite retrograde signals from the chloroplast

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Gonzalo Martín Estavillo

2013-01-01

Full Text Available Plant organelles produce retrograde signals to alter nuclear gene expression in order to coordinate their biogenesis, maintain homeostasis or optimize their performance under adverse conditions. Many signals of different chemical nature have been described in the past decades, including chlorophyll intermediates, reactive oxygen species and adenosine derivatives. While the effects of retrograde signalling on gene expression are well understood, the initiation and transport of the signals and their mode of action have either not been resolved, or are a matter of speculation. Moreover, retrograde signalling should be consider as part of a broader cellular network, instead of as separate pathways, required to adjust to changing physiologically relevant conditions. Here we summarize current plastid retrograde signalling models in plants, with a focus on new signalling pathways, SAL1-PAP, MEcPP and β- cyclocitral, and outline missing links or future areas of research that we believe need to be addressed to have a better understanding of plant intracellular signalling networks.

The Effect of the Rotor Static Eccentricity on the Electro-Mechanical Coupled Characteristics of the Motorized Spindle

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Wu Zaixin

2016-01-01

Full Text Available High-speed motorized spindle is a multi-variable, non-linear and strong coupling system. The rotor static eccentricity is inevitable because of machining or assembling error. The rotor static eccentricities have an important effect on the electromechanical coupled characteristics of the motorized spindle. In this paper, the electromechanical coupled mathematical model of the motorized spindle was set up. The mathematical model includes mechanical and electrical equation. The mechanical and electrical equation is built up by the variational principle. Furthermore, the inductance parameters without the rotor static eccentricity and the inductance parameters with rotor static eccentricity have been calculated by the winding function method and the high speed motorized spindle was simulated. The result show that the rotor static eccentricity can delay the starting process of the motorized spindle, and at steady state, the rotor circuit currents are still large because of the rotor static eccentricity.

Stability of Multi-Planet Systems in the Alpha Centauri System

Science.gov (United States)

Lissauer, Jack J.

2017-01-01

We evaluate the extent of the regions within the alpha Centauri AB star system where small planets are able to orbit for billion-year timescales (Quarles & Lissauer 2016, Astron. J. 151, 111), as well as how closely-spaced planetary orbits can be within those regions in which individual planets can survive. Although individual planets on low inclination, low eccentricity, orbits can survive throughout the habitable zones of both stars, perturbations from the companion star imply that the spacing of planets in multi-planet systems within the habitable zones of each star must be significantly larger than the spacing of similar multi-planet systems orbiting single stars in order to be long-lived. Because the binary companion induces a forced eccentricity upon the orbits of planets in orbit around either star, appropriately-aligned circumstellar orbits with small initial eccentricities are stable to slightly larger initial semimajor axes than are initially circular orbits. Initial eccentricities close to forced eccentricities can have a much larger affect on how closely planetary orbits can be spaced, and therefore on how many planets may remain in the habitable zones, although the required spacing remains significantly higher than for planets orbiting single stars.

Sonourethrography compared to retrograde urethrography

International Nuclear Information System (INIS)

Kim, Jong Chul; Chang, Nam Sik; Park, Cheong Hee; Rhee, Byung Chul; Kong, Jae Chul; Park, Jong Yoon

1989-01-01

A total of 15 patients with suspected urethral stricture or fistula underwent conventional retrograde urethrography and following sonourethrography with saline infusion or voiding against Eschmann penile clamp, in Gyeongsang and Chungnam National University Hospital from July, 1989 to June, 1989. The sonographic findings were as diagnostic as the roentgen findings in 12 patients. When the length of the strictures assessed by each imaging modality was compared to measurement at open urothroplasty of 2 patients, sonourethrography was consistently more accurate. Urethroscopy was done in all cases. Sonourethrography using distension technique of the urethra enabled classification of the degree of spongiofibrosis, thus provided the guidance of direct vision internal urethrotomy in 9 patients. In 2 patients, the sonourethrogram identified periurethral tumor and urethral polyp which were not definitely analysed on the retrograde urethrogram. In the patient of posttraumatic postoperative urethrorectal fistula, residual fistuous tract was seen on both examinations. In 1 patient of stricture with severe periurethral scar, urethral stricture recurred after graft. No patient reported significant discomfort during the sonourethrogram. The sonourethrogram provided valuable, dynamic. 3 dimensional information about the luminal and extraluminal anatomy and pathology of the anterior urethra. The new method of sonourethrogram allows for the appropriate decision to be made easier for optimal treatment of urethal stricture, etc, and can be used as a follow up study

NEW PRECISION ORBITS OF BRIGHT DOUBLE-LINED SPECTROSCOPIC BINARIES. IV. 66 ANDROMEDAE, HR 6979, AND HR 9059

International Nuclear Information System (INIS)

Fekel, Francis C.; Williamson, Michael H.; Tomkin, Jocelyn

2010-01-01

We have determined improved spectroscopic orbits for three double-lined binaries, 66 And (F4 V), HR 6979 (Am), and HR 9059 (F5 IV) using radial velocities from the 2.1 m telescope at McDonald Observatory, the coude feed telescope at Kitt Peak National Observatory, and 2 m telescope at Fairborn Observatory. The orbital periods range from 11.0 to 14.3 days, and all three systems have eccentric orbits. The new orbital dimensions (a 1 sin i and a 2 sin i) and minimum masses (m 1 sin 3 i and m 2 sin 3 i) have accuracies of 0.2% or better. All six components of the three binary systems are rotating more slowly than their predicted pseudosynchronous rotational velocities. Hipparcos photometry of HR 9059 shows that this system has partial eclipses. Its components are nearly identical in mass and are at the very end of their main-sequence lifetimes or perhaps have just begun to traverse the Hertsprung gap.

METRIC: A Dedicated Earth-Orbiting Spacecraft for Investigating Gravitational Physics and the Space Environment

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Roberto Peron

2017-07-01

Full Text Available A dedicated mission in low Earth orbit is proposed to test predictions of gravitational interaction theories and to directly measure the atmospheric density in a relevant altitude range, as well as to provide a metrological platform able to tie different space geodesy techniques. The concept foresees a small spacecraft to be placed in a dawn-dusk eccentric orbit between 450 and 1200 km of altitude. The spacecraft will be tracked from the ground with high precision, and a three-axis accelerometer package on-board will measure the non-gravitational accelerations acting on its surface. Estimates of parameters related to fundamental physics and geophysics should be obtained by a precise orbit determination, while the accelerometer data will be instrumental in constraining the atmospheric density. Along with the mission scientific objectives, a conceptual configuration is described together with an analysis of the dynamical environment experienced by the spacecraft and the accelerometer.

Liver parenchumography following endoscopic retrograde cholangiopancreatography (ERCP)

International Nuclear Information System (INIS)

Revert, A.; Arana, E.; Pertejo, V.; Berenguer, M.; Masip, M.J.

1998-01-01

Focal liver opacification during endoscopic retrograde cholangiography (ERCP) is an uncommon complication caused by excessive pressure during contrast injection. In this situation, ERCP must be interrupted and the position of the cannula checked. We recommend that these images be excluded from the diagnosis of tumor or cystic cavities. 4 refs

The effect of different accentuated eccentric load levels in eccentric-concentric loading contractions on acute neuromuscular, growth hormone and blood lactate responses during a hypertrophic protocol

OpenAIRE

Ojasto, Timo

2007-01-01

When accentuated load is applied during the eccentric (ECC) phase of eccentric-concentric (ECC-CON) contractions, it is defined as dynamic accentuated external resistance (DAER) exercise. This study monitored acute neuromuscular responses, growth hormone (GH) and blood lactate (La) concentrations to find out the most efficient ECC-CON loading strategy for muscle hypertrophy by employing various DAER resistances in the bench-press. Male subjects (age=32.4±4.3years, n=11) were assigned as subje...

Seismic analysis of a reactor building with eccentric layout

International Nuclear Information System (INIS)

Itoh, T.; Deng, D.Z.F.; Lui, K.

1987-01-01

Conventional design for a reactor building in a high seismic area has adopted an essentially concentric layout in response to fear of excessive torsional effect due to horizontal seismic load on an eccentric plant. This concentric layout requirement generally results in an inflexible arrangement of the plant facilities and thus increases the plant volume. This study is performed to investigate the effect of eccentricity on the overall seismic structural response and to provide technical information in this regard to substantiate the volume reduction of the overall power plant. The plant layout is evolved from the Bechtel standard plan of a PWR plant by integrating the reactor building and the auxiliary building into a combined building supported on a common basemat. This plant layout is optimized for volume utilization and to reduce the length of piping systems. The mass centers at various elevations of the combined building do not coincide with the rigidity center (RC) of the respective floor and the geometric center of the basemat, thus creating an eccentric response of the building in a seismic environment. Therefore, the torsional effects of the structure have to be taken into account in the seismic analysis

Retrograde cystography US. A new ultrasound technique for the diagnosis and staging of vesicoureteral reflux

International Nuclear Information System (INIS)

Farina, R.; Arena, C.; Pennisi, F.; Di Benedetto, V.; Politi, G.; Di Benedetto, A.

1999-01-01

The authors investigated the accuracy of a new US (ultrasound) investigation technique, called retrograde cystography US, in the early diagnosis and staging of vesicoureteral reflux. 5 patients, aged 3 months to 10 years, suffering from hydronephrosis and/or pyelonephritis, were examined using retrograde cystography US followed by conventional retrograde cystography. Retrograde cystography US consists in the transcatheter introduction of a contrast agent into the bladder and a subsequent color Doppler examination to show or exclude the presence of reflux. Superpubic scanning of bladder, ureters and pyelocaliceal cavity was performed after echo contrast agent introduction to assess the reflux grade. US was performed with an Esaote AU 590 asynchronous scanner with a 3.5 MHz convex probe. The total agreement of conventional and US findings seems to confirm the importance of the US method for the diagnosis and staging of vesicoureteral reflux [it

Orbit covariance propagation via quadratic-order state transition matrix in curvilinear coordinates

Science.gov (United States)

Hernando-Ayuso, Javier; Bombardelli, Claudio

2017-09-01

In this paper, an analytical second-order state transition matrix (STM) for relative motion in curvilinear coordinates is presented and applied to the problem of orbit uncertainty propagation in nearly circular orbits (eccentricity smaller than 0.1). The matrix is obtained by linearization around a second-order analytical approximation of the relative motion recently proposed by one of the authors and can be seen as a second-order extension of the curvilinear Clohessy-Wiltshire (C-W) solution. The accuracy of the uncertainty propagation is assessed by comparison with numerical results based on Monte Carlo propagation of a high-fidelity model including geopotential and third-body perturbations. Results show that the proposed STM can greatly improve the accuracy of the predicted relative state: the average error is found to be at least one order of magnitude smaller compared to the curvilinear C-W solution. In addition, the effect of environmental perturbations on the uncertainty propagation is shown to be negligible up to several revolutions in the geostationary region and for a few revolutions in low Earth orbit in the worst case.

A high-fidelity N-body ephemeris generator for satellites in Earth orbit

Science.gov (United States)

Simmons, David R.

1991-10-01

A program is currently used for mission planning called the Analytic Satellite Ephemeris Program (ASEP), which produces projected data for orbits that remain fairly close to Earth. Lunar and solar perturbations are taken into account in another program called GRAVE. This project is a revision of GRAVE which incorporates more flexible means of input for initial data, provides additional kinds of output information, and makes use of structured programming techniques to make the program more understandable and reliable. The computer program ORBIT was tested against tracking data for the first 313 days of operation of the CRRES satellite. A sample graph is given comparing the semi-major axis calculated by the program with the values supplied by NORAD. When calculated for points at which CRRES passes through the ascending node, the argument of perigee, the right ascension of the ascending node, and the mean anomaly all stay within about a degree of the corresponding values from NORAD; the inclination of the orbital plane is much closer. The program value of the eccentricity is in error by no more than 0.0002.

Dating of retrograde metamorphism in Western Carpathians by K-Ar analysis of muscovites

International Nuclear Information System (INIS)

Cambel, B.; Korikovskij, S.P.; Krasivskaya, I.S.; Arakelyants, M.M.

1986-01-01

Using the K-Ar isotope dating method of muscovites it was found that many retrogradely metamorphosed rocks are the results of Variscan retrograde metamorphism and are not pre-Cambrian or Alpine metamorphites (diaphthorites). Samples for dating were taken from the Western Carpathian crystalline formation. The content of radiogenic argon was determined by mass spectrometry using the method of isotope dilution. (M.D.)

Ultrasound-Guided Percutaneous Electrolysis and Eccentric Exercises for Subacromial Pain Syndrome: A Randomized Clinical Trial

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José L. Arias-Buría

2015-01-01

Full Text Available Objective. To compare effects of ultrasound- (US- guided percutaneous electrolysis combined with an eccentric exercise program of the rotator cuff muscles in subacromial pain syndrome. Methods. Thirty-six patients were randomized and assigned into US-guided percutaneous electrolysis (n=17 group or exercise (n=19 group. Patients were asked to perform an eccentric exercise program of the rotator cuff muscles twice every day for 4 weeks. Participants assigned to US-guided percutaneous electrolysis group also received the application of galvanic current through acupuncture needle on each session once a week (total 4 sessions. Shoulder pain (NPRS and disability (DASH were assessed at baseline, after 2 sessions, and 1 week after the last session. Results. The ANOVA revealed significant Group∗Time interactions for shoulder pain and disability (all, P<0.01: individuals receiving US-guided percutaneous electrolysis combined with the eccentric exercises experienced greater improvement than those receiving eccentric exercise alone. Conclusions. US-guided percutaneous electrolysis combined with eccentric exercises resulted in small better outcomes at short term compared to when only eccentric exercises were applied in subacromial pain syndrome. The effect was statistically and clinically significant for shoulder pain but below minimal clinical difference for function. Future studies should investigate the long-term effects and potential placebo effect of this intervention.

Endoskopisk ultralydvejledt rendezvouskolangiografi ved mislykket endoskopisk retrograd kolangiopankreatikografi

DEFF Research Database (Denmark)

Boman, Pia Snedker; Perdawid, Sharafaden Karim; Lykkegaard, John

2012-01-01

In this case report we describe an alternative method of cholangiography. Endoscopic retrograde cholangiopancreatography (ERCP) was not successful in a patient with choledocolithiasis. A combined endoscopic ultrasound (EUS) and ERCP procedure was performed and a stent was inserted in the common...

EFFECT OF HEAT PRECONDITIONING BY MICROWAVE HYPERTHERMIA ON HUMAN SKELETAL MUSCLE AFTER ECCENTRIC EXERCISE

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Norio Saga

2008-03-01

Full Text Available The purpose of this study was to clarify whether heat preconditioning results in less eccentric exercise-induced muscle damage and muscle soreness, and whether the repeated bout effect is enhanced by heat preconditioning prior to eccentric exercise. Nine untrained male volunteers aged 23 ± 3 years participated in this study. Heat preconditioning included treatment with a microwave hyperthermia unit (150 W, 20 min that was randomly applied to one of the subject's arms (MW; the other arm was used as a control (CON. One day after heat preconditioning, the subjects performed 24 maximal isokinetic eccentric contractions of the elbow flexors at 30°·s-1 (ECC1. One week after ECC1, the subjects repeated the procedure (ECC2. After each bout of exercise, maximal voluntary contraction (MVC, range of motion (ROM of the elbow joint, upper arm circumference, blood creatine kinase (CK activity and muscle soreness were measured. The subjects experienced both conditions at an interval of 3 weeks. MVC and ROM in the MW were significantly higher than those in the CON (p < 0.05 for ECC1; however, the heat preconditioning had no significant effect on upper arm circumference, blood CK activity, or muscle soreness following ECC1 and ECC2. Heat preconditioning may protect human skeletal muscle from eccentric exercise-induced muscle damage after a single bout of eccentric exercise but does not appear to promote the repeated bout effect after a second bout of eccentric exercise

Constraints on the atmospheric circulation and variability of the eccentric hot Jupiter XO-3b

Energy Technology Data Exchange (ETDEWEB)

Wong, Ian; Knutson, Heather A. [Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125 (United States); Cowan, Nicolas B. [Center for Interdisciplinary Exploration and Astrophysics (CIERA), Department of Earth and Planetary Sciences, Department of Physics and Astronomy, Northwestern University, 2145 Sheridan Road, Evanston, IL 60208 (United States); Lewis, Nikole K. [Department of Earth, Atmospheric, and Planetary Sciences, Massachusetts Institute of Technology, Cambridge, MA 02139 (United States); Agol, Eric [Department of Astronomy, University of Washington, Seattle, WA 98195 (United States); Burrows, Adam [Department of Astrophysical Sciences, Princeton University, Princeton, NJ 08544 (United States); Deming, Drake [Department of Astronomy, University of Maryland, College Park, MD 20742 (United States); Fortney, Jonathan J.; Laughlin, Gregory [Department of Astronomy and Astrophysics, University of California at Santa Cruz, Santa Cruz, CA 95604 (United States); Fulton, Benjamin J. [Institute for Astronomy, University of Hawaii, Honolulu, HI 96822 (United States); Langton, Jonathan [Department of Physics, Principia College, Elsah, IL 62028 (United States); Showman, Adam P., E-mail: iwong@caltech.edu [Lunar and Planetary Laboratory, University of Arizona, Tucson, AZ 85721 (United States)

2014-10-20

We report secondary eclipse photometry of the hot Jupiter XO-3b in the 4.5 μm band taken with the Infrared Array Camera on the Spitzer Space Telescope. We measure individual eclipse depths and center of eclipse times for a total of 12 secondary eclipses. We fit these data simultaneously with two transits observed in the same band in order to obtain a global best-fit secondary eclipse depth of 0.1580% ± 0.0036% and a center of eclipse phase of 0.67004 ± 0.00013. We assess the relative magnitude of variations in the dayside brightness of the planet by measuring the size of the residuals during ingress and egress from fitting the combined eclipse light curve with a uniform disk model and place an upper limit of 0.05%. The new secondary eclipse observations extend the total baseline from one and a half years to nearly three years, allowing us to place an upper limit on the periastron precession rate of 2.9 × 10{sup –3} deg day{sup –1}— the tightest constraint to date on the periastron precession rate of a hot Jupiter. We use the new transit observations to calculate improved estimates for the system properties, including an updated orbital ephemeris. We also use the large number of secondary eclipses to obtain the most stringent limits to date on the orbit-to-orbit variability of an eccentric hot Jupiter and demonstrate the consistency of multiple-epoch Spitzer observations.

SU-F-T-51: Investigating the Effect of Eye Size and Eccentricity On Normal Tissue Doses From Eye Plaque Brachytherapy

Energy Technology Data Exchange (ETDEWEB)

Polsdofer, E; Crilly, R [Oregon Health & Science University Portland, OR (United States)

2016-06-15

Purpose: This study investigates the effect of eye size and eccentricity on doses to critical tissues by simulating doses in the Plaque Simulator (v. 6.3.1) software. Present OHSU plaque brachytherapy treatment focuses on delivering radiation to the tumor measured with ocular ultrasound plus a small margin and assumes the orbit has the dimensions of a “standard eye.” Accurately modeling the dimensions of the orbit requires a high resolution ocular CT. This study quantifies how standard differences in equatorial diameters and eccentricity affect calculated doses to critical structures in order to query the justification of the additional CT scan to the treatment planning process. Methods: Tumors of 10 mm × 10 mm × 5 mm were modeled at the 12:00:00 hour with a latitude of 45 degrees. Right eyes were modeled at a number of equatorial diameters from 17.5 to 28 mm for each of the standard non-notched COMS plaques with silastic inserts. The COMS plaques were fully loaded with uniform activity, centered on the tumor, and prescribed to a common tumor dose (85 Gy/100 hours). Variations in the calculated doses to normal structures were examined to see if the changes were significant. Results: The calculated dose to normal structures show a marked dependence on eye geometry. This is exemplified by fovea dose which more than doubled in the smaller eyes and nearly halved in the larger model. Additional significant dependence was found in plaque size on the calculated dose in spite of all plaques giving the same dose to the prescription point. Conclusion: The variation in dose with eye dimension fully justifies the addition of a high resolution ocular CT to the planning technique. Additional attention must be made to plaque size beyond simply covering the tumor when considering normal tissue dose.

Effects of concentric vs eccentric loading on cardiovascular ...

African Journals Online (AJOL)

Effects of concentric vs eccentric loading on cardiovascular variables and ECG. Madan Bhavna1*, Sarika, Sandhu J.S1. 1. Department of Sports Medicine and Physiotherapy Guru Nanak Dev University; ..... psychological and performance.

Effect of load eccentricity and stress level on monopile support for offshore wind turbines

DEFF Research Database (Denmark)

Klinkvort, Rasmus Tofte; Hededal, Ole

2014-01-01

on which load is applied with a large eccentricity. With centrifuge tests as the basis, this paper investigates the behaviour of a rigid pile loaded with a high eccentricity. A test series was carried out to simulate idealized monotonic load cases for monopiles supporting an offshore wind turbine....... Centrifuge tests were performed on model monopiles subjected to stress distributions equal to prototype monopiles with pile diameters ranging from 1–5 m and eccentricities ranging from 8.25–17.75 pile diameters. It was possible to identify a unified response of all of these tests by using dimensional...... analysis and Rankine’s passive earth pressure coefficient as a normalization parameter. The normalized ultimate soil resistance was unaffected by acceleration level and load eccentricity, indicating that the failure mechanism was the same for all tests. Based on the centrifuge tests, a reformulation...

Endoscopic retrograde cholangiopancreatography causes reduced myocardial blood flow

DEFF Research Database (Denmark)

Christensen, M; Hendel, H W; Rasmussen, V

2002-01-01

BACKGROUND AND STUDY AIMS: Previous studies have shown that up to 50% of healthy patients may develop ST-segment changes during upper gastrointestinal endoscopy. The aim of the study was to evaluate myocardial blood flow in patients during endoscopic retrograde cholangiopancreatography (ERCP...

Mission Analysis and Orbit Control of Interferometric Wheel Formation Flying

Science.gov (United States)

Fourcade, J.

Flying satellite in formation requires maintaining the specific relative geometry of the spacecraft with high precision. This requirement raises new problem of orbit control. This paper presents the results of the mission analysis of a low Earth observation system, the interferometric wheel, patented by CNES. This wheel is made up of three receiving spacecraft, which follow an emitting Earth observation radar satellite. The first part of this paper presents trades off which were performed to choose orbital elements of the formation flying which fulfils all constraints. The second part presents orbit positioning strategies including reconfiguration of the wheel to change its size. The last part describes the station keeping of the formation. Two kinds of constraints are imposed by the interferometric system : a constraint on the distance between the wheel and the radar satellite, and constraints on the distance between the wheel satellites. The first constraint is fulfilled with a classical chemical station keeping strategy. The second one is fulfilled using pure passive actuators. Due to the high stability of the relative eccentricity of the formation, only the relative semi major axis had to be controlled. Differential drag due to differential attitude motion was used to control relative altitude. An autonomous orbit controller was developed and tested. The final accuracy is a relative station keeping better than few meters for a wheel size of one kilometer.

Temporalis muscle hypertrophy and reduced skull eccentricity in Duchenne muscular dystrophy.

Science.gov (United States)

Straathof, C S M; Doorenweerd, N; Wokke, B H A; Dumas, E M; van den Bergen, J C; van Buchem, M A; Hendriksen, J G M; Verschuuren, J J G M; Kan, H E

2014-10-01

Muscle hypertrophy and muscle weakness are well known in Duchenne muscular dystrophy. Decreased muscle force can have secondary effects on skeletal growth and development such as facial and dental morphology changes. In this study, we quantified temporal muscle thickness, circumference, and eccentricity of the skull and the head on T1-weighted magnetic resonance imaging (MRI) scans of the head of 15 Duchenne muscular dystrophy patients and 15 controls. Average temporal muscle thickness was significantly increased in patients (12.9 ± 5.2 mm) compared to controls (6.8 ± 1.4 mm) (P muscle thickness and skull eccentricity were significantly negatively correlated in patients, and positively in controls. Hypertrophy of the temporal muscles and changes in skull eccentricity appear to occur early in the course of Duchenne muscular dystrophy. Further studies in younger patients are needed to confirm a causal relationship. © The Author(s) 2014.

Eccentric exercise: acute and chronic effects on healthy and diseased tendons.

Science.gov (United States)

Kjaer, Michael; Heinemeier, Katja M

2014-06-01

Eccentric exercise can influence tendon mechanical properties and matrix protein synthesis. mRNA for collagen and regulatory factors thereof are upregulated in animal tendons, independent of muscular contraction type, supporting the view that tendon, compared with skeletal muscle, is less sensitive to differences in type and/or amount of mechanical stimulus with regard to expression of collagen, regulatory factors for collagen, and cross-link regulators. In overused (tendinopathic) human tendon, eccentric exercise training has a beneficial effect, but the mechanism by which this is elicited is unknown, and slow concentric loading appears to have similar beneficial effects. It may be that tendinopathic regions, as long as they are subjected to a certain magnitude of load at a slow speed, independent of whether this is eccentric or concentric in nature, can reestablish their normal tendon fibril alignment and cell morphology. Copyright © 2014 the American Physiological Society.

Cardioplegia retrógrada seqüencial Sequencial retrograde cardioplegy

Directory of Open Access Journals (Sweden)

Otoni M Gomes

1996-09-01

extracorporeal circulation established. The following routes were employed for cardioplegic perfusion: 1 Antegrade - through ascending aortic canullation bellow the aortic occlusion clamp;2 Selective retrograde - through coronary synus (Co.S - 25 mmHg using a self-inflating ballooned cannula; 3 Total retrograde, (Co.S - 40 mmHg - through a cannula inserted in the right atrium (RA; 4 Sequencial retrograde, Co.S-RA - with the CS flowing first through the coronary synus lowering the interventricular septal temperature to 16 ºC and after through the RA cannula as in the total retrograde technique with the pulmonary artery occluded and;5 Sequencial retrograde, Co.S-RV - the RV chamber being directly cannulated through the tricuspid valve and perfused, instead of the RA in the latter technique. The temperature variation of the myocardium in the left ventricule (LV, RVt RA and sinus node region (SN was controlled employing an Omega needle termistor and thermometer. With the antegrade technique (70 mmHg pressure the most uniform myocardial cooling, the lowest CS volume and perfusion time duration was observed, followed In excelence by the Co.S-RA Sequencial retrograde technique and the Co.S-RV sequencial technique. The present data indicate that sequencial retrograde cardioplegic perfusion techinique is significantly better than the usual Co.S or RA total retrograde technique alone for myocardial protection when compared with the aortic root antegrade perfusion technique.

Metabolic and anti-inflammatory benefits of eccentric endurance exercise - a pilot study.

Science.gov (United States)

Drexel, H; Saely, C H; Langer, P; Loruenser, G; Marte, T; Risch, L; Hoefle, G; Aczel, S

2008-04-01

Eccentric endurance exercise (e.g. hiking downwards) is less strenuous than concentric exercise (e.g. hiking upwards) but its potential to reduce cardiovascular risk is unknown. We randomly allocated 45 healthy sedentary individuals (16 men and 29 women, mean age 48 years) to one of two groups, one beginning with two months of hiking upwards, the other with two months of hiking downwards the same route, with a crossover for a further two months. For the opposite way, a cable car was used where compliance was recorded electronically. The difference in altitude was 540 metres; the distance was covered three to five times a week. Fasting and postprandial metabolic profiles were obtained at baseline and after the two month periods of eccentric and concentric exercise, respectively. Forty-two of the 45 participants completed the study; the compliance rate was therefore 93%. Compared with baseline, eccentric exercise lowered total cholesterol (by 4.1%; P = 0.026), low-density lipoprotein (LDL) cholesterol (by 8.4%, P = 0.001), Apolipoprotein B/Apolipoprotein A1 ratio (by 10.9%, P < 0.001), homeostasis model assessment of insulin resistance scores (by 26.2%, P = 0.017) and C-reactive protein (by 30.0%; P = 0.007); the magnitude of these changes was comparable to that of concentric exercise. Eccentric exercise improved glucose tolerance (by 6.2%, P = 0.023), whereas concentric exercise improved triglyceride tolerance (by 14.9%, P = 0.022). Eccentric endurance exercise is a promising new exercise modality with favourable metabolic and anti-inflammatory effects and is well applicable to sedentary individuals.

Multiple-indicator dilution technique for characterization of normal and retrograde flow in once-through rat liver perfusions

International Nuclear Information System (INIS)

St-Pierre, M.V.; Schwab, A.J.; Goresky, C.A.; Lee, W.F.; Pang, K.S.

1989-01-01

The technique of normal and retrograde rat liver perfusion has been widely used to probe zonal differences in drug-metabolizing activities. The validity of this approach mandates the same tissue spaces being accessed by substrates during both normal and retrograde perfusions. Using the multiple-indicator dilution technique, we presently examine the extent to which retrograde perfusion alters the spaces accessible to noneliminated references. A bolus dose of 51Cr-labeled red blood cells, 125I-albumin, 14C-sucrose and 3H2O was injected into the portal (normal) or hepatic (retrograde) vein of rat livers perfused at 10 ml per min per liver. The outflow perfusate was serially collected over 220 sec to characterize the transit times and the distribution spaces of the labels. During retrograde perfusion, red blood cells, albumin and sucrose profiles peaked later and lower than during normal perfusion, whereas the water curves were similar. The transit times of red blood cells, albumin and sucrose were longer (p less than 0.005), whereas those for water did not change. Consequently, retrograde flow resulted in significantly larger sinusoidal blood volumes (45%), albumin Disse space (42%) and sucrose Disse space (25%) than during normal flow, whereas the distribution spaces for total and intracellular water remained unaltered. The distension of the vascular tree was confirmed by electron microscopy, by which occasional isolated foci of widened intercellular recesses and spaces of Disse were observed. Cellular ultrastructure was otherwise unchanged, and there was no difference found between normal and retrograde perfusion for bile flow rates, AST release, perfusion pressure, oxygen consumption and metabolic removal of ethanol, a substrate with flow-limited distribution, which equilibrates rapidly with cell water (hepatic extraction ratios were virtually identical: normal vs. retrograde, 0.50 vs. 0.48 at 6 to 7.4 mM input concentration)

Twelve months follow-up after retrograde recanalization of superficial femoral artery chronic total occlusion

Directory of Open Access Journals (Sweden)

Joanna Wojtasik-Bakalarz

2017-03-01

Full Text Available Introduction : Fifty percent of cases of peripheral artery disease are caused by chronic total occlusion (CTO of the superficial femoral artery (SFA. Ten–fifteen percent of percutaneous SFA recanalization procedures are unsuccessful. In those cases the retrograde technique can increase the success rate of the procedure, but the long-term follow-up of such procedures is still unknown. Aim : To assess the efficacy and clinical outcomes during long-term follow-up after retrograde recanalization of the SFA. Material and methods: We included patients after at least one unsuccessful percutaneous antegrade recanalization of the SFA. Patients were evaluated for the procedural and clinical follow-up of mean time 13.9 months. Results: The study included 17 patients (7 females, 10 males who underwent percutaneous retrograde recanalization of the SFA from June 2011 to June 2015. The mean age of patients was 63 ±7 years. Retrograde puncture of the distal SFA was successful in all cases. A retrograde procedure was performed immediately after antegrade failure in 4 (23.5% patients and after a previously failed attempt in 13 (76.5% patients. The procedure was successful in 15 (88.2% patients, and unsuccessful in 2 (11.8% patients. Periprocedural complications included 1 peripheral distal embolization (successfully treated with aspiration thrombectomy, 1 bleeding event from the puncture site and 7 puncture site hematomas. During follow-up the all-cause mortality rate was 5.8% (1 patient, non-cardiac death. The primary patency rate at 12 months was 88.2% and secondary patency 100%. Conclusions : The retrograde SFA puncture seems to be a safe and successful technique for CTO recanalization and is associated with a low rate of perioperative and long-term follow-up complications.

Achilles tendon of wistar rats treated with laser therapy and eccentric exercise

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Maria Verônica de Souza

2015-10-01

Full Text Available ABSTRACTIntroduction:Both laser therapy and eccentric exercises are used in tendon injuries. However, the association of these physiotherapeutic modalities is yet little investigated.Objective:To evaluate the effect of low-level laser therapy associated to eccentric exercise (downhill walking on Achilles tendinopathy of Wistar rats.Method:Eighteen Achilles tendon from 15 adult male Wistar rats were used. Tendons were distributed in six groups (laser, eccentric exercise, laser and eccentric exercise, rest, contralateral tendon, and healthy tendon. Unilateral tendinopathy was surgically induced by transversal compression followed by scarification of tendon fibers. The treatments laser therapy (904 nm, 3J/cm² and/or eccentric exercise (downhill walking; 12 m/min; 50 min/day; 15o inclination treadmill began 24 hours after surgery and remained for 20 days. Clinical and biomechanical analyzes were conducted. Achilles tendon was macroscopically evaluated and the transversal diameter measured. Euthanasia was performed 21 days after lesion induction. Tendons of both limbs were collected and frozen at -20°C until biomechanical analysis, on which the characteristic of maximum load (N, stress at ultimate (MPa and maximum extension (mm were analyzed.Results:Swelling was observed within 72 hours postoperative. No fibrous adhesions were observed nor increase in transversal diameter of tendons. Animals with the exercised tendons, but not treated with laser therapy, presented lower (p=0.0000 locomotor capacity. No difference occurred be-tween groups for the biomechanical characteristics maximum load (p=0.4379, stress at ultimate (p=0.4605 and maximum extension (p=0.3820 evaluated, even considering healthy and contralateral tendons.Conclusion:The concomitant use of low-level laser and the eccentric exercise of downhill walking, starting 24 hours after surgically induced tendinopathy, do not result in a tendon with the same biomechanical resistance or elasticity

The mechanism for efficacy of eccentric loading in Achilles tendon injury; an in vivo study in humans.

Science.gov (United States)

Rees, J D; Lichtwark, G A; Wolman, R L; Wilson, A M

2008-10-01

Degenerative disorders of tendons present an enormous clinical challenge. They are extremely common, prone to recur and existing medical and surgical treatments are generally unsatisfactory. Recently eccentric, but not concentric, exercises have been shown to be highly effective in managing tendinopathy of the Achilles (and other) tendons. The mechanism for the efficacy of these exercises is unknown although it has been speculated that forces generated during eccentric loading are of a greater magnitude. Our objective was to determine the mechanism for the beneficial effect of eccentric exercise in Achilles tendinopathy. Seven healthy volunteers performed eccentric and concentric loading exercises for the Achilles tendon. Tendon force and length changes were determined using a combination of motion analysis, force plate data and real-time ultrasound. There was no significant difference in peak tendon force or tendon length change when comparing eccentric with concentric exercises. However, high-frequency oscillations in tendon force occurred in all subjects during eccentric exercises but were rare in concentric exercises (P < 0.0001). These oscillations provide a mechanism to explain the therapeutic benefit of eccentric loading in Achilles tendinopathy and parallels recent evidence from bone remodelling, where the frequency of the loading cycles is of more significance than the absolute magnitude of the force.

Experimental Investigations on Axially and Eccentrically Loaded Masonry Walls

Science.gov (United States)

Keshava, Mangala; Raghunath, Seshagiri Rao

2017-12-01

In India, un-reinforced masonry walls are often used as main structural components in load bearing structures. Indian code on masonry accounts the reduction in strength of walls by using stress reduction factors in its design philosophy. This code was introduced in 1987 and reaffirmed in 1995. The present study investigates the use of these factors for south Indian masonry. Also, with the gaining popularity in block work construction, the aim of this study was to find out the suitability of these factors given in the Indian code to block work masonry. Normally, the load carrying capacity of masonry walls can be assessed in three ways, namely, (1) tests on masonry constituents, (2) tests on masonry prisms and (3) tests on full-scale wall specimens. Tests on bricks/blocks, cement-sand mortar, brick/block masonry prisms and 14 full-scale brick/block masonry walls formed the experimental investigation. The behavior of the walls was investigated under varying slenderness and eccentricity ratios. Hollow concrete blocks normally used as in-fill masonry can be considered as load bearing elements as its load carrying capacity was found to be high when compared to conventional brick masonry. Higher slenderness and eccentricity ratios drastically reduced the strength capacity of south Indian brick masonry walls. The reduction in strength due to slenderness and eccentricity is presented in the form of stress reduction factors in the Indian code. These factors obtained through experiments on eccentrically loaded brick masonry walls was lower while that of brick/block masonry under axial loads was higher than the values indicated in the Indian code. Also the reduction in strength is different for brick and block work masonry thus indicating the need for separate stress reduction factors for these two masonry materials.

Preserved memory in retrograde amnesia: sparing of a recently acquired skill.

Science.gov (United States)

Squire, L R; Cohen, N J; Zouzounis, J A

1984-01-01

Recent work with amnesic patients has revealed a preserved capacity for acquiring and retaining new skills despite otherwise profound anterograde impairment. In addition to their anterograde impairment, amnesic patients also have retrograde memory loss for some information acquired prior to the amnesic event. The present experiment addresses for the first time the question of whether preservation of memory for skills is also a feature memory impairment. To determine the susceptibility of a recently learned skill to retrograde amnesia, we taught patients to read mirror-reversed words before and during the early part of a prescribed course of electroconvulsive therapy (ECT) and then tested retention of the skill after the course of treatment had been completed. Patients prescribed bilateral or right unilateral ECT and depressed patients not receiving ECT acquired the mirror-reading skill at the same rate and then retained it at the same level. For the patients prescribed ECT, intact learning and retention of the skill occurred despite retrograde amnesia for the previous testing sessions and for the words that they had read previously.

Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy for gingival carcinoma

International Nuclear Information System (INIS)

Mukai, Y.; Hata, M.; Koike, I.; Inoue, T.; Mitsudo, K.; Koizumi, T.; Oguri, S.; Kioi, M.; Tohnai, I.; Omura, M.

2014-01-01

The aim of this study was to review the efficacy and toxicity of radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy in the treatment of gingival carcinoma. In all, 34 patients (21 men and 13 women) with squamous cell carcinoma of the gingiva underwent radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy. Treatment consisted of daily external irradiation and concurrent retrograde superselective intra-arterial infusion with cisplatin and docetaxel. A median total dose of 60 Gy in 30 fractions was delivered to tumors. Of the 34 patients, 29 (85 %) achieved a complete response (CR) and 5 had residual tumors. Of the 29 patients with a CR, 2 had local recurrences and 1 had distant metastasis 1-15 months after treatment. Twenty-six of the 36 patients had survived at a median follow-up time of 36 months (range 12-79 months); 4 died of cancer and 4 died of non-cancer-related causes. At both 3 and 5 years after treatment, the overall survival rates were 79 % and the cause-specific survival rates were 85 %. Osteoradionecrosis of the mandibular bone only developed in 1 patient after treatment. Radiation therapy with concurrent retrograde superselective intra-arterial chemotherapy was effective and safe in the treatment of gingival carcinoma. This treatment may be a promising curative and organ-preserving treatment option for gingival carcinoma. (orig.) [de

The therapeutic effect of crocin on ketamine-induced retrograde amnesia in rats

Directory of Open Access Journals (Sweden)

Namdar Yousefvand

2016-09-01

Full Text Available Introduction: The glutamatergic system plays an important role in learning and memory. Administration of crocus sativus (Saffron or its constituent, crocin, facilitates the formation of memory. This research investigated the effect of crocin on antagonizing retrograde amnesia induced by ketamine, a glutamatergic receptor antagonist, in rats by shuttle box. Methods: Male Wistar rats were tested to measure their learning behavior in the passive avoidance task. All animals were trained by a 1 mA shock. The drugs were injected immediately after the training was successfully performed. The animals were tested 24h after training to measure Step Through Latency (STL. Results: On the test day, administration of ketamine (12 mg/kg, ip impaired the memory after training. Different doses of crocin (2, 5 or 10 mg/kg, ip were injected 30 min after ketamine, but only 2 mg/kg crocin could improve retrograde amnesia and 5 and 10 mg/kg doses did not have any significant effect on retrograde amnesia. Moreover, administration of crocin (2, 5 or 10 mg/kg, ip after training had no significant impact on passive avoidance memory by itself. Conclusion: Considering the therapeutic effect of post-training administration of crocin on ketamine-induced retrograde amnesia, it can be argued that crocin has an interaction with glutamatergic system in formation of passive avoidance memory in rats.

Loss of Huntingtin stimulates capture of retrograde dense-core vesicles to increase synaptic neuropeptide stores.

Science.gov (United States)

Bulgari, Dinara; Deitcher, David L; Levitan, Edwin S

2017-08-01

The Huntington's disease protein Huntingtin (Htt) regulates axonal transport of dense-core vesicles (DCVs) containing neurotrophins and neuropeptides. DCVs travel down axons to reach nerve terminals where they are either captured in synaptic boutons to support later release or reverse direction to reenter the axon as part of vesicle circulation. Currently, the impact of Htt on DCV dynamics in the terminal is unknown. Here we report that knockout of Drosophila Htt selectively reduces retrograde DCV flux at proximal boutons of motoneuron terminals. However, initiation of retrograde transport at the most distal bouton and transport velocity are unaffected suggesting that synaptic capture rate of these retrograde DCVs could be altered. In fact, tracking DCVs shows that retrograde synaptic capture efficiency is significantly elevated by Htt knockout or knockdown. Furthermore, synaptic boutons contain more neuropeptide in Htt knockout larvae even though bouton size, single DCV fluorescence intensity, neuropeptide release in response to electrical stimulation and subsequent activity-dependent capture are unaffected. Thus, loss of Htt increases synaptic capture as DCVs travel by retrograde transport through boutons resulting in reduced transport toward the axon and increased neuropeptide in the terminal. These results therefore identify native Htt as a regulator of synaptic capture and neuropeptide storage. Copyright © 2017 Elsevier GmbH. All rights reserved.

Eccentric Exercises Reduce Hamstring Strains in Elite Adult Male Soccer Players: A Critically Appraised Topic.

Science.gov (United States)

Shadle, Ian B; Cacolice, Paul A

2017-11-01

Clinical Scenario: Hamstring strains are a common sport-related injury, which may limit athletic performance for an extended period of time. These injuries are common in the soccer setting. As such, it is important to determine an appropriate prevention program to minimize the risk of such an injury for these athletes. Eccentric hamstring training may be an effective and practical hamstring strain prevention strategy. What is the effect of eccentric exercises on hamstring strain prevention in adult male soccer players? Summary of Key Findings: Current literature was searched for studies of level 2 evidence or higher that investigated the effect of eccentric exercises in preventing hamstring strains in adult male soccer players. Three articles returned from the literature search met the inclusion criteria. A fourth article looked at differences in strength gains between eccentric and concentric hamstring strengthening exercises, but did not record hamstring strain incidence. A fifth article, a systematic review, met all the criteria except for the correct population. Of the 3 studies, 2 were randomized control trails and 1 was a cohort study. Clinical Bottom Line: There is robust supportive evidence that eccentric hamstring exercises can prevent a hamstring injury to an elite adult male soccer player. Therefore, it is recommended that athletic trainers and other sports medicine providers evaluate current practices relating to reducing hamstring strains and consider implementing eccentric exercise based prevention programs. Strength of Recommendation: All evidence was attained from articles with a level of evidence 2b or higher, based on the Center for Evidence-Based Medicine (CEBM) criteria, stating that eccentric exercises can decrease hamstring strains.

Topographic Anterograde and Retrograde Memory for Spatial ...

African Journals Online (AJOL)

The present study was on the effects of haloperidol injection on anterograde and retrograde topographic memories for spatial behaviours in Long Evan rats. Twelve Long Evan albino rats weighing 0.5 – 0.8 kg (6 males, 6 females) were used for the study. Complex Maze Box of 14 unit T Alley from the Royal Institute of ...

Effect of eccentric exercise on the healing process of injured patellar tendon in rats.

Science.gov (United States)

Nakamura, Kenichi; Kitaoka, Katsuhiko; Tomita, Katsuro

2008-07-01

Earlier studies have reported positive results from eccentric training in patients with tendon disorders. The reasons for the beneficial clinical effects of eccentric training are not known. Vascularization followed by regression of the vasculature enhances the healing response of injured tendons. Eccentric exercise induces a more beneficial healing response than concentric exercise. Sixty rats with patellar tendon injuries were divided into three groups: nonexercise controls (group N; n = 20); concentric exercise group (group C; n = 20); eccentric exercise group (group E; n = 20). Each rat was taught to run uphill or downhill for 14 days. Patellar tendons were removed 1, 4, 7, 10, and 14 days following injury. Vascular endothelial growth factor (VEGF), angiopoietin-1, and angiopoietin-2 were measured by reverse transcription polymerase chain reaction. In group C, VEGF mRNA was increased 1 and 4 days following injury but was decreased on days 7, 10, and 14. In group E, VEGF mRNA was elevated only on day 1. In group N, VEGF mRNA remained at a low level throughout all 14 days. The angiopoietin-2/angiopoietin-1 ratio was higher for group C than for group E. In the presence of VEGF, angiopoietin-1 promotes vessel stability, whereas angiopoietin-2 has the opposite effect. Eccentric exercise contributes to stabilized angiogenesis during the early phase of tendon injury. Conversely, concentric exercise, which induces destabilized angiogenesis, leads to a delayed healing response. Initiation of eccentric exercise immediately after tendon injury may help improve healing by reducing vascularity.