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Sample records for vy canis majoris

  1. Distance to VY Canis Majoris with VERA

    OpenAIRE

    Choi, Yoon Kyung; Hirota, Tomoya; Honma, Mareki; Kobayashi, Hideyuki; Bushimata, Takeshi; Imai, Hiroshi; Iwadate, Kenzaburo; Jike, Takaaki; Kameno, Seiji; Kameya, Osamu; Kamohara, Ryuichi; Kan-ya, Yukitoshi; Kawaguchi, Noriyuki; Kijima, Masachika; Kim, Mi Kyoung

    2008-01-01

    We report astrometric observations of H2O masers around the red supergiant VY Canis Majoris (VY CMa) carried out with VLBI Exploration of Radio Astrometry (VERA). Based on astrometric monitoring for 13 months, we successfully measured a trigonometric parallax of 0.88 +/- 0.08 mas, corresponding to a distance of 1.14 +0.11/-0.09 kpc. This is the most accurate distance to VY CMa and the first one based on an annual parallax measurement. The luminosity of VY CMa has been overestimated due to a p...

  2. Distance to VY Canis Majoris with VERA

    Science.gov (United States)

    Choi, Yoon Kyung; Hirota, Tomoya; Honma, Mareki; Kobayashi, Hideyuki; Bushimata, Takeshi; Imai, Hiroshi; Iwadate, Kenzaburo; Jike, Takaaki; Kameno, Seiji; Kameya, Osamu; Kamohara, Ryuichi; Kan-Ya, Yukitoshi; Kawaguchi, Noriyuki; Kijima, Masachika; Kim, Mi Kyoung; Kuji, Seisuke; Kurayama, Tomoharu; Manabe, Seiji; Maruyama, Kenta; Matsui, Makoto; Matsumoto, Naoko; Miyaji, Takeshi; Nagayama, Takumi; Nakagawa, Akiharu; Nakamura, Kayoko; Oh, Chung Sik; Omodaka, Toshihiro; Oyama, Tomoaki; Sakai, Satoshi; Sasao, Tetsuo; Sato, Katsuhisa; Sato, Mayumi; Shibata, Katsunori M.; Tamura, Yoshiaki; Tsushima, Miyuki; Yamashita, Kazuyoshi

    2008-10-01

    We report on astrometric observations of H2O masers around the red supergiant VY Canis Majoris carried out with VLBI Exploration of Radio Astrometry (VERA). Based on astrometric monitoring for 13 months, we successfully measured a trigonometric parallax of 0.88±0.08 mas, corresponding to a distance of 1.14+0.11-0.09kpc. This is the most accurate determined distance to VY CMa and the first one based on an annual parallax measurement. The luminosity of VY CMa has been overestimated due to a previously accepted distance. With our result, we re-estimated the luminosity of VY CMa to be (3±0.5) × 105Lodot using the bolometric flux integrated over optical and IR wavelengths. This improved luminosity value makes the location of VY CMa on the Hertzsprung-Russell (HR) diagram much closer to the theoretically allowable zone (i.e. the left side of the Hayashi track) than previous ones, though the uncertainty in the effective temperature of the stellar surface still does not permit us to make a final conclusion.

  3. Large dust grains in the wind of VY Canis Majoris

    OpenAIRE

    Scicluna, P.; Siebenmorgen, R.; Wesson, R.; Blommaert, J. A. D. L; Kasper, M.; Voshchinnikov, N. V.; Wolf, S.

    2015-01-01

    Massive stars live short lives, losing large amounts of mass through their stellar wind. Their mass is a key factor determining how and when they explode as supernovae, enriching the interstellar medium with heavy elements and dust. During the red supergiant phase, mass-loss rates increase prodigiously, but the driving mechanism has proven elusive. Here we present high-contrast optical polarimetric-imaging observations of the extreme red supergiant VY Canis Majoris and its clumpy, dusty, mass...

  4. Astrometry of red supergiant VY Canis Majoris with VERA

    Science.gov (United States)

    Choi, Y. K.; Hirota, T.; Honma, M.; Kobayashi, H.

    2008-07-01

    We present observational results on the red supergiant VY Canis Majoris with VERA. We have observed 22 GHz H2O masers and 43 GHz SiO masers (v=1 and 2 J=1-0) around VY CMa for 13 months. We succesfully detected a parallax of 0.87 ± 0.08 mas, corresponding to the distance of 1.15 +0.10-0.09 kpc using H2O masers. As the result of phase-referencing analyses, we have measured absolute positions for both H2O masers and SiO masers. The H2O maser features show rapid expansion off the central star.

  5. Large dust grains in the wind of VY Canis Majoris

    Science.gov (United States)

    Scicluna, P.; Siebenmorgen, R.; Wesson, R.; Blommaert, J. A. D. L.; Kasper, M.; Voshchinnikov, N. V.; Wolf, S.

    2015-12-01

    Massive stars live short lives, losing large amounts of mass through their stellar wind. Their mass is a key factor determining how and when they explode as supernovae, enriching the interstellar medium with heavy elements and dust. During the red supergiant phase, mass-loss rates increase prodigiously, but the driving mechanism has proven elusive. Here we present high-contrast optical polarimetric-imaging observations of the extreme red supergiant VY Canis Majoris and its clumpy, dusty, mass-loss envelope, using the new extreme-adaptive-optics instrument SPHERE at the VLT. These observations allow us to make the first direct and unambiguous detection of submicron dust grains in the ejecta; we derive an average grain radius ~0.5 μm, 50 times larger than in the diffuse ISM, large enough to receive significant radiation pressure by photon scattering. We find evidence for varying grain sizes throughout the ejecta, highlighting the dynamical nature of the envelope. Grains with 0.5 μm sizes are likely to reach a safe distance from the eventual explosion of VY Canis Majoris; hence it may inject upwards of 10-2 M⊙ of dust into the ISM. Based on observations made with European Southern Observatory (ESO) telescopes at the La Silla Paranal Observatory under program 60.A-9368(A).Appendix A is available in electronic form at http://www.aanda.org

  6. Spatial heterodyne interferometry of VY Canis Majoris, alpha Orionis, alpha Scorpii, and R Leonis at 11 microns

    International Nuclear Information System (INIS)

    Sutton, E.C.; Storey, J.W.V.; Betz, A.L.; Townes, C.H.; Spears, D.L.

    1977-01-01

    Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec

  7. Astrometry of the Red Supergiant Star VY Canis Majoris with VERA

    Science.gov (United States)

    Choi, Y. K.; Hirota, T.; Honma, M.; Kobayashi, H.

    2009-08-01

    We present observational results on the red supergiant VY Canis Majoris with VERA. We have observed 22 GHz H_2O masers and 43 GHz SiO masers (v=1 and 2 J=1-0) around VY CMa for 13 months. We successfully detected a parallax of 0.87 ± 0.08 mas, corresponding to 1.15 +0.10 -0.09 kpc of distance using H_2O masers. As results of phase--referencing analyses, we have measured absolute positions for both the H_2O masers and SiO masers. The proper motions of the H_2O masers show the tendency of expansion.

  8. The 3D morphology of the ejecta surrounding VY Canis Majoris

    Science.gov (United States)

    Jones, Terry Jay; Humphreys, Roberta M.; Helton, L. Andrew

    2007-03-01

    We use second epoch images taken with WFPC2 on the HST and imaging polarimetry taken with the HST/ACS/HRC to explore the three dimensional structure of the circumstellar dust distribution around the red supergiant VY Canis Majoris. Transverse motions, combined with radial velocities, provide a picture of the kinematics of the ejecta, including the total space motions. The fractional polarization and photometric colors provide an independent method of locating the physical position of the dust along the line-of-sight. Most of the individual arc-like features and clumps seen in the intensity image are also features in the fractional polarization map, and must be distinct geometric objects. The location of these features in the ejecta of VY CMa using kinematics and polarimetry agree well with each other, and strongly suggest they are the result of relatively massive ejections, probably associated with magnetic fields.

  9. ISO observations of far-infrared rotational emission lines of water vapor toward the supergiant star VY Canis Majoris

    OpenAIRE

    Neufeld, David A.; Feuchtgruber, Helmut; Harwit, Martin; Melnick, Gary J.

    1999-01-01

    We report the detection of numerous far-infrared emission lines of water vapor toward the supergiant star VY Canis Majoris. A 29.5 - 45 micron grating scan of VY CMa, obtained using the Short Wavelength Spectrometer (SWS) of the Infrared Space Observatory (ISO) at a spectral resolving power of approximately 2000, reveals at least 41 spectral features due to water vapor that together radiate a total luminosity ~ 25 solar luminosities. In addition to pure rotational transitions within the groun...

  10. The 3D Morphology of VY Canis Majoris II: Polarimetry and the Line-of-Sight Distribution of the Ejecta

    OpenAIRE

    Jones, Terry Jay; Humphreys, Roberta M.; Helton, L. Andrew; Gui, Changfeng; Huang, Xiang

    2007-01-01

    We use imaging polarimetry taken with the HST/ACS/HRC to explore the three dimensional structure of the circumstellar dust distribution around the red supergiant VY Canis Majoris. The polarization vectors of the nebulosity surrounding VY CMa show a strong centro-symmetric pattern in all directions except directly East and range from 10% - 80% in fractional polarization. In regions that are optically thin, and therefore likely have only single scattering, we use the fractional polarization and...

  11. Dust-forming molecules in VY Canis Majoris (and Betelgeuse)

    OpenAIRE

    Kaminski, T.; Gottlieb, C. A.; Schmidt, M. R.; Patel, N. A.; Young, K. H.; Menten, K. M.; Brunken, S.; Muller, H. S. P.; Winters, J. M.; McCarthy, M. C.

    2013-01-01

    The formation of inorganic dust in circumstellar environments of evolved stars is poorly understood. Spectra of molecules thought to be most important for the nucleation, i.e. AlO, TiO, and TiO2, have been recently detected in the red supergiant VY CMa. These molecules are effectively formed in VY CMa and the observations suggest that non-equilibrium chemistry must be involved in their formation and nucleation into dust. In addition to exploring the recent observations of VY CMa, we briefly d...

  12. Dust-forming molecules in VY Canis Majoris (and Betelgeuse)

    Science.gov (United States)

    Kamiński, T.; Gottlieb, C. A.; Schmidt, M. R.; Patel, N. A.; Young, K. H.; Menten, K. M.; Brünken, S.; Müller, H. S. P.; Winters, J. M.; McCarthy, M. C.

    2013-05-01

    The formation of inorganic dust in circumstellar environments of evolved stars is poorly understood. Spectra of molecules thought to be most important for the nucleation, i.e. AlO, TiO, and TiO2, have been recently detected in the red supergiant VY CMa. These molecules are effectively formed in VY CMa and the observations suggest that non-equilibrium chemistry must be involved in their formation and nucleation into dust. In addition to exploring the recent observations of VY CMa, we briefly discuss the possibility of detecting these molecules in the "dust-poor" circumstellar environment of Betelgeuse.

  13. VY Canis Majoris: The Astrophysical Basis of Its Luminosity

    Science.gov (United States)

    Gehrz, Robert D.; Humphreys, R. M.; Jones, T. J.

    2006-12-01

    The luminosity of the famous red supergiant VY CMa ( L = 4 5 x 105 L ) is well-determined from its spectral energy distribution and distance, and places it near the empirical upper luminosity limit for cool hypergiants. In contrast, its surface temperature is fundamentally ill-defined. Implications for its location on the HR Diagram and its apparent size are discussed.

  14. VY Canis Majoris: The Astrophysical Basis of Its Luminosity

    OpenAIRE

    Humphreys, Roberta M.

    2006-01-01

    The luminosity of the famous red supergiant VY CMa (L ~ 4 - 5 x 10e5 Lsun) is well-determined from its spectral energy distribution and distance, and places it near the empirical upper luminosity limit for cool hypergiants. In contrast, its surface temperature is fundamentally ill-defined. Both contradict a recent paper by Massey, Levesque and Plez (2006). Implications for its location on the HR Diagram and its apparent size are discussed.

  15. The Spectrum of VY Canis Majoris in 2000 February

    Science.gov (United States)

    Wallerstein, George; Gonzalez, Guillermo

    2001-08-01

    We present the current (2000 February) status of the optical spectrum of the irregularly variable M supergiant VY CMa, based on high-resolution CCD spectra. The emission spectrum is largely unchanged over the past 43 yr, with low-lying atomic lines as well as the molecules TiO and ScO in emission. Tables of observed wavelengths for both identified and unidentified lines are presented.

  16. The Asymmetric Nebula Surrounding the Extreme Red Supergiant VY Canis Majoris

    Science.gov (United States)

    Smith, Nathan; Humphreys, Roberta M.; Davidson, Kris; Gehrz, Robert D.; Schuster, M. T.; Krautter, Joachim

    2001-02-01

    We present HST/WFPC2 images plus ground-based infrared images and photometry of the very luminous OH/IR star VY Canis Majoris. Our WFPC2 data show a complex distribution of knots and filamentary arcs in the asymmetric reflection nebula around the obscured central star. The reflection arcs may result from multiple, asymmetric ejection episodes due to localized events on VY CMa's surface. Such events probably involve magnetic fields and convection, by analogy with solar activity. Surface photometry indicates that the star may have experienced enhanced mass loss over the past 1000 yr. We also demonstrate that the apparent asymmetry of the nebula results from a combination of high extinction and backscattering by dust grains. Thermal-infrared images reveal a more symmetric distribution, elongated along a nearly east-west direction. VY CMa probably has a flattened disklike distribution of dust with a northeast-southwest polar axis and may be experiencing activity analogous to solar prominences. The presence of an axis of symmetry raises interesting questions for a star the size of Saturn's orbit. Magnetic fields and surface activity may play an important role in VY CMa's mass-loss history. Based on observations made with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  17. Rapid Fluctuations of Water Maser Emission in VY Canis Majoris

    Science.gov (United States)

    Zheng, Xing Wu; Scalise, Eugenio, Jr.; Han, Fu

    1998-11-01

    We report the observational results of short timescale monitoring of the 22 GHz water maser emission in VY CMa. A quasi-sinusoidal fluctuation has been detected with the relative flux intensity change of 20%-25% and a period of 10.3 day for two dominant features. This detected variability appears to be superimposed on the normal maser lines. We cannot easily explain the rapid fluctuation with the variation of the radiative input or the strong interstellar scintillation along the line of sight. The variation may be caused by the periodic shock.

  18. Aluminium oxide in the optical spectrum of VY Canis Majoris

    Science.gov (United States)

    Kamiński, T.; Schmidt, M. R.; Menten, K. M.

    2013-01-01

    We report the first identification of the optical bands of the B 2Σ + -X 2Σ + system of AlO in the red supergiant VY CMa. In addition to TiO, VO, ScO, and YO, which were recognized in the optical spectrum of the star long time ago, AlO is another refractory molecule which displays strong emission bands in this peculiar star. Simulating the bands of AlO, we derive a rotational temperature of the circumstellar gas of Trot = 700 K. By resolving individual rotational components of the bands, we derive the kinematical characteristics of the gas, finding that the emission is centred at the stellar radial velocity and its intrinsic width is 13.5 km s-1 (full width at half maximum). It is the narrowest emission among all (thermal) features observed in VY CMa so far. The temperature and line widths suggest that the emission arises in gas located within ~20 stellar radii, where the outflow is still being accelerated. This result contradicts equilibrium-chemistry models which predict substantial AlO abundances only to within a few stellar radii. We argue that non-equilibrium models involving propagation of shocks are needed to explain the observations. This work makes use of data acquired within the ESO programmes 67.B-0504 and DDT 266.D-5655, and observations from the AAVSO International Database.

  19. 557 GHz Observations of Water Vapor Outflow from VY Canis Majoris and W Hydrae

    Science.gov (United States)

    Harwit, Martin; Bergin, Edwin A.

    2002-02-01

    We report the first detection of thermal water vapor emission in the 557 GHz, 110-101 ground-state transition of ortho-H2O toward VY Canis Majoris. In observations obtained with the Submillimeter Wave Astronomy Satellite, we measured a flux of ~450 Jy, in a spectrally resolved line centered on a velocity vLSR=25 km s-1 with an FWHM of ~35 km s-1, somewhat dependent on the assumed line shape. We analyze the line shape in the context of three different radial outflow models for which we provide analytical expressions. We also detected a weaker 557 GHz emission line from W Hydrae. We find that these and other H2O emission-line strengths scale as suggested by Zubko and Elitzur.

  20. Unveiling the molecular bipolar outflow of the peculiar red supergiant VY Canis Majoris

    Science.gov (United States)

    Shinnaga, Hiroko; Claussen, Mark J.; Lim, Jeremy; Dinh-van-Trung; Tsuboi, Masato

    2003-04-01

    We carried out polarimetric spectral-line imaging of the molecular outflow of the peculiar red supergiant VY Canis Majoris in SiO J=1-0 line in the ground vibrational state, which contains highly linearly-polarized velocity components, using the Very Large Array. We succeeded in unveiling the highly linearly polarized bipolar outflow for the first time at subarcsecond spatial resolution. The results clearly show that the direction of linear polarization of the brightest maser components is parallel to the outflow axis. The results strongly suggest that the linear polarization of the SiO maser is closely related to the outflow phenomena of the star. Furthermore, the results indicate that the linear polarization observed in the optical and infrared also occur due to the outflow phenomena.

  1. The Infrared Continuum Spectrum of VY Canis Majoris

    Science.gov (United States)

    Harwit, Martin; Malfait, Koen; Decin, Leen; Waelkens, Christoffel; Feuchtgruber, Helmut; Melnick, Gary J.

    2001-08-01

    We combine spectra of VY CMa obtained with the short- and long-wavelength spectrometers, SWS and LWS, on the Infrared Space Observatory3 to provide a first detailed continuum spectrum of this highly luminous star. The circumstellar dust cloud through which the star is observed is partially self-absorbing, which makes for complex computational modeling. We review previous work and comment on the range of uncertainties about the physical traits and mineralogical composition of the modeled disk. We show that these uncertainties significantly affect the modeling of the outflow and the estimated mass loss. In particular, we demonstrate that a variety of quite diverse models can produce good fits to the observed spectrum. If the outflow is steady, and the radiative repulsion on the dust cloud dominates the star's gravitational attraction, we show that the total dust mass loss rate is ~4×10-6 Msolar yr-1, assuming that the star is at a distance of 1.5 kpc. Several indications, however, suggest that the outflow from the star may be spasmodic. We discuss this and other problems facing the construction of a physically coherent model of the dust cloud and a realistic mass-loss analysis.

  2. VY Canis Majoris: Observational Studies of the Outflow

    Science.gov (United States)

    Harwit, M.

    2001-12-01

    A number of recent studies carried out with the Infrared Space Observatory, ISO, and the Submillimeter Wave Astronomy Satellite, SWAS, provide new information on the chemical composition of the dust and the geometry of the outflow. With ISO, we have obtained a near-, mid-, and far-infrared spectrum of VY CMa that shows the strong preponderance of amorphous, as contrasted to crystalline, silicates. The sharp spectral slope in the near-infrared suggests the presence also of iron grains. While an excellent theoretical fit to the data is obtained, we emphasize that this is far from unique. A resolution of ambiguities will require a self-consistent model that considers not only radiative transfer, but also plausible elemental abundances, laboratory studies of chemical condensation sequences, and gas dynamics. With SWAS we have obtained a high-resolution spectrum of the 557GHz ground state transition of ortho-water. The spectral profile enables us to rule out a number of outflow geometries proposed in the literature. With ISO we also obtained the intensities and velocity structure of several other spectral lines of water. Most of these lines must be optically thick but effectively thin, a circumstance that permits us to make use of recent gas-dynamic models to locate the radial position in the outflow where individual lines are emitted.

  3. An Interferometric Spectral Line and Imaging Survey of VY Canis Majoris in the 345 GHz Band

    Science.gov (United States)

    Kamiński, T.; Gottlieb, C. A.; Young, K. H.; Menten, K. M.; Patel, N. A.

    2013-12-01

    A spectral line survey of the oxygen-rich red supergiant VY Canis Majoris was made between 279 and 355 GHz with the Submillimeter Array (SMA). Two hundred twenty-three spectral features from 19 molecules (not counting isotopic species of some of them) were observed, including the rotational spectra of TiO, TiO2, and AlCl for the first time in this source. The parameters and an atlas of all spectral features are presented. Observations of each line with a synthesized beam of ~0.''9, reveal the complex kinematics and morphology of the nebula surrounding VY CMa. Many of the molecules are observed in high-lying rotational levels or in excited vibrational levels. From these, it was established that the main source of the submillimeter-wave continuum (dust) and the high-excitation molecular gas (the star) are separated by about 0.''15. Apparent coincidences between the molecular gas observed with the SMA, and some of the arcs and knots observed at infrared wavelengths and in the optical scattered light by the Hubble Space Telescope are identified. The observations presented here provide important constraints on the molecular chemistry in oxygen-dominated circumstellar environments and a deeper picture of the complex circumstellar environment of VY CMa.

  4. Mapping the Spatial Distribution of Metal-Bearing Oxides in VY Canis Majoris

    Science.gov (United States)

    Burkhardt, Andrew; Booth, S. Tom; Remijan, Anthony; Carroll, Brandon; Ziurys, Lucy M.

    2015-06-01

    The formation of silicate-based dust grains is not well constrained. Despite this, grain surface chemistry is essential to modern astrochemical formation models. In carbon-poor stellar envelopes, such as the red hypergiant VY Canis Majoris (VY CMa), metal-bearing oxides, the building blocks of silicate grains, dominate the grain formation, and thus are a key location to study dust chemistry. TiO_2, which was only first detected in the radio recently (Kaminski et al., 2013a), has been proposed to be a critical molecule for silicate grain formation, and not oxides containing more abundant metals (eg. Si, Fe, and Mg) (Gail and Sedlmayr, 1998). In addition, other molecules, such as SO_2, have been found to trace shells produced by numerous outflows pushing through the expanding envelope, resulting in a complex velocity structure (Ziurys et al., 2007). With the advanced capabilities of ALMA, it is now possible to individually resolve the velocity structure of each of these outflows and constrain the underlying chemistry in the region. Here, we present high resolution maps of rotational transitions of several metal-bearing oxides in VY CMa from the ALMA Band 7 and Band 9 Science Verification observations. With these maps, the physical parameters of the region and the formation chemistry of metal-bearing oxides will be studied.

  5. Molecular Abundances in the Circumstellar Envelope of Oxygen-Rich Supergiant VY Canis Majoris

    Science.gov (United States)

    Edwards, Jessica L.; Ziurys, Lucy

    2014-06-01

    A complete set of molecular abundances have been established for the Oxygen-rich circumstellar envelope (CSE) surrounding the supergiant star VY Canis Majoris (VY CMa). These data were obtained from The Arizona Radio Observatory (ARO) 1-mm spectral line survey of this object using the ARO Sub-millimeter Telescope (SMT), as well as complimentary transitions taken with the ARO 12-meter. The non-LTE radiative transfer code ESCAPADE has been used to obtain the molecular abundances and distributions in VY CMa, including modeling of the various asymmetric outflow geometries in this source. For example, SO and SO2 were determined to arise from five distinct outflows, four of which are asymmetric with respect to the central star. Abundances of these two sulfur-bearing molecules range from 3 x 10-8 - 2.5 x 10-7 for the various outflows. Similar results will be presented for molecules like CS, SiS, HCN, and SiO, as well as more exotic species like NS, PO, AlO, and AlOH. The molecular abundances between the various outflows will be compared and implications for supergiant chemistry will be discussed.

  6. Strong magnetic field generated by the extreme oxygen-rich red supergiant VY Canis Majoris

    Science.gov (United States)

    Shinnaga, Hiroko; Claussen, Mark J.; Yamamoto, Satoshi; Shimojo, Masumi

    2017-12-01

    Evolved stars experience high mass-loss rates forming thick circumstellar envelopes (CSEs). The circumstellar material is made of the result of stellar nucleosynthesis and, as such, plays a crucial role in the chemical evolution of galaxies and the universe. Since asymmetric geometries of CSEs are common, and with very complex structures for some cases, radiative pressure from the stars can explain only a small portion of the mass-loss processes; thus the essential driving mechanism is still unknown, particularly for high-mass stars. Here we report on magnetic field measurements associated with the well-known extreme red supergiant (RSG) VY Canis Majoris (VY CMa). We measured the linear polarization and the Zeeman splitting of the SiO v = 0, J = 1-0 transition using a sensitive radio interferometer. The measured magnetic field strengths are surprisingly high; their upper limits range between 150 and 650 G within 530 au (˜80 R*) of the star. The lower limit of the field strength is expected to be at least ˜10 G based on the high degree of linear polarization. Since the field strengths are very high, the magnetic field must be a key element in understanding the stellar evolution of VY CMa, as well as the dynamical and chemical evolution of the complex CSE of the star. M-type RSGs, with large stellar surface, were thought to be very slow rotators. This would seem to make a dynamo in operation difficult, and would also dilute any fossil magnetic field. At least for VY CMa, we expect that powerful dynamo processes must still be active to generate the intense magnetic field.

  7. Chemical complexity in the winds of the oxygen-rich supergiant star VY Canis Majoris

    Science.gov (United States)

    Ziurys, L. M.; Milam, S. N.; Apponi, A. J.; Woolf, N. J.

    2007-06-01

    The interstellar medium is enriched primarily by matter ejected from old, evolved stars. The outflows from these stars create spherical envelopes, which foster gas-phase chemistry. The chemical complexity in circumstellar shells was originally thought to be dominated by the elemental carbon to oxygen ratio. Observations have suggested that envelopes with more carbon than oxygen have a significantly greater abundance of molecules than their oxygen-rich analogues. Here we report observations of molecules in the oxygen-rich shell of the red supergiant star VY Canis Majoris (VY CMa). A variety of unexpected chemical compounds have been identified, including NaCl, PN, HNC and HCO+. From the spectral line profiles, the molecules can be distinguished as arising from three distinct kinematic regions: a spherical outflow, a tightly collimated, blue-shifted expansion, and a directed, red-shifted flow. Certain species (SiO, PN and NaCl) exclusively trace the spherical flow, whereas HNC and sulphur-bearing molecules (amongst others) are selectively created in the two expansions, perhaps arising from shock waves. CO, HCN, CS and HCO+ exist in all three components. Despite the oxygen-rich environment, HCN seems to be as abundant as CO. These results suggest that oxygen-rich shells may be as chemically diverse as their carbon counterparts.

  8. CARBON CHEMISTRY IN THE ENVELOPE OF VY CANIS MAJORIS: IMPLICATIONS FOR OXYGEN-RICH EVOLVED STARS

    International Nuclear Information System (INIS)

    Ziurys, L. M.; Tenenbaum, E. D.; Pulliam, R. L.; Woolf, N. J.; Milam, S. N.

    2009-01-01

    Observations of the carbon-bearing molecules CO, HCN, CS, HNC, CN, and HCO + have been conducted toward the circumstellar envelope of the oxygen-rich red supergiant star, VY Canis Majoris (VY CMa), using the Arizona Radio Observatory (ARO). CO and HCN were also observed toward the O-rich shells of NML Cyg, TX Cam, IK Tau, and W Hya. Rotational transitions of these species at 1 mm, 0.8 mm, and 0.4 mm were measured with the ARO Submillimeter Telescope, including the J = 6 → 5 line of CO at 691 GHz toward TX Cam and W Hya. The ARO 12 m was used for 2 mm and 3 mm observations. Four transitions were observed for HCO + in VY CMa, the first definitive identification of this ion in a circumstellar envelope. Molecular line profiles from VY CMa are complex, indicating three separate outflows: a roughly spherical flow and separate red- and blueshifted winds, as suggested by earlier observations. Spectra from the other sources appear to trace a single outflow component. The line data were modeled with a radiative transfer code to establish molecular abundances relative to H 2 and source distributions. Abundances for CO derived for these objects vary over an order of magnitude, f ∼ 0.4-5 x 10 -4 , with the lower values corresponding to the supergiants. For HCN, a similar range in abundance is found (f ∼ 0.9-9 x 10 -6 ), with no obvious dependence on the mass-loss rate. In VY CMa, HCO + is present in all three outflows with f ∼ 0.4-1.6 x 10 -8 and a spatial extent similar to that of CO. HNC is found only in the red- and blueshifted components with [HCN]/[HNC] ∼ 150-190, while [CN]/[HCN] ∼ 0.01 in the spherical flow. All three velocity components are traced in CS, which has a confined spatial distribution and f ∼ 2-6 x 10 -7 . These observations suggest that carbon-bearing molecules in O-rich shells are produced by a combination of photospheric shocks and photochemistry. Shocks may play a more prominent role in the supergiants because of their macroturbulent

  9. Carbon Chemistry in the Envelope of VY Canis Majoris: Implications for Oxygen-Rich Evolved Stars

    Science.gov (United States)

    Ziurys, L. M.; Tenenbaum, E. D.; Pulliam, R. L.; Woolf, N. J.; Milam, S. N.

    2009-04-01

    Observations of the carbon-bearing molecules CO, HCN, CS, HNC, CN, and HCO+ have been conducted toward the circumstellar envelope of the oxygen-rich red supergiant star, VY Canis Majoris (VY CMa), using the Arizona Radio Observatory (ARO). CO and HCN were also observed toward the O-rich shells of NML Cyg, TX Cam, IK Tau, and W Hya. Rotational transitions of these species at 1 mm, 0.8 mm, and 0.4 mm were measured with the ARO Submillimeter Telescope, including the J = 6 → 5 line of CO at 691 GHz toward TX Cam and W Hya. The ARO 12 m was used for 2 mm and 3 mm observations. Four transitions were observed for HCO+ in VY CMa, the first definitive identification of this ion in a circumstellar envelope. Molecular line profiles from VY CMa are complex, indicating three separate outflows: a roughly spherical flow and separate red- and blueshifted winds, as suggested by earlier observations. Spectra from the other sources appear to trace a single outflow component. The line data were modeled with a radiative transfer code to establish molecular abundances relative to H2 and source distributions. Abundances for CO derived for these objects vary over an order of magnitude, f ~ 0.4-5 × 10-4, with the lower values corresponding to the supergiants. For HCN, a similar range in abundance is found (f ~ 0.9-9 × 10-6), with no obvious dependence on the mass-loss rate. In VY CMa, HCO+ is present in all three outflows with f ~ 0.4-1.6 × 10-8 and a spatial extent similar to that of CO. HNC is found only in the red- and blueshifted components with [HCN]/[HNC] ~ 150-190, while [CN]/[HCN] ~ 0.01 in the spherical flow. All three velocity components are traced in CS, which has a confined spatial distribution and f ~ 2-6 × 10-7. These observations suggest that carbon-bearing molecules in O-rich shells are produced by a combination of photospheric shocks and photochemistry. Shocks may play a more prominent role in the supergiants because of their macroturbulent velocities.

  10. Arcsecond Resolution Mapping of Sulfur Dioxide Emission in the Circumstellar Envelope of VY Canis Majoris

    Science.gov (United States)

    Fu, Roger R.; Moullet, Arielle; Patel, Nimesh A.; Biersteker, John; Derose, Kimberly L.; Young, Kenneth H.

    2012-02-01

    We report Submillimeter Array observations of SO2 emission in the circumstellar envelope (CSE) of the red supergiant VY Canis Majoris, with an angular resolution of ≈1''. SO2 emission appears in three distinct outflow regions surrounding the central continuum peak emission that is spatially unresolved. No bipolar structure is noted in the sources. A fourth source of SO2 is identified as a spherical wind centered at the systemic velocity. We estimate the SO2 column density and rotational temperature assuming local thermal equilibrium (LTE) as well as perform non-LTE radiative transfer analysis using RADEX. Column densities of SO2 are found to be ~1016 cm-2 in the outflows and in the spherical wind. Comparison with existing maps of the two parent species OH and SO shows the SO2 distribution to be consistent with that of OH. The abundance ratio f_{SO_{2}}/f_{SO} is greater than unity for all radii larger than 3 × 1016 cm. SO2 is distributed in fragmented clumps compared to SO, PN, and SiS molecules. These observations lend support to specific models of circumstellar chemistry that predict f_{SO_{2}}/f_{SO}>1 and may suggest the role of localized effects such as shocks in the production of SO2 in the CSE.

  11. ARCSECOND RESOLUTION MAPPING OF SULFUR DIOXIDE EMISSION IN THE CIRCUMSTELLAR ENVELOPE OF VY CANIS MAJORIS

    International Nuclear Information System (INIS)

    Fu, Roger R.; Moullet, Arielle; Patel, Nimesh A.; Biersteker, John; Derose, Kimberly L.; Young, Kenneth H.

    2012-01-01

    We report Submillimeter Array observations of SO 2 emission in the circumstellar envelope (CSE) of the red supergiant VY Canis Majoris, with an angular resolution of ≈1''. SO 2 emission appears in three distinct outflow regions surrounding the central continuum peak emission that is spatially unresolved. No bipolar structure is noted in the sources. A fourth source of SO 2 is identified as a spherical wind centered at the systemic velocity. We estimate the SO 2 column density and rotational temperature assuming local thermal equilibrium (LTE) as well as perform non-LTE radiative transfer analysis using RADEX. Column densities of SO 2 are found to be ∼10 16 cm –2 in the outflows and in the spherical wind. Comparison with existing maps of the two parent species OH and SO shows the SO 2 distribution to be consistent with that of OH. The abundance ratio f SO 2 /f SO is greater than unity for all radii larger than 3 × 10 16 cm. SO 2 is distributed in fragmented clumps compared to SO, PN, and SiS molecules. These observations lend support to specific models of circumstellar chemistry that predict f SO 2 /f SO >1 and may suggest the role of localized effects such as shocks in the production of SO 2 in the CSE.

  12. An Interferometric Spectral-Line and Imaging Survey of VY Canis Majoris in the 345 GHz Band

    OpenAIRE

    Kaminski, T.; Gottlieb, C. A.; Young, K. H.; Menten, K. M.; Patel, N. A.

    2013-01-01

    A spectral line survey of the oxygen-rich red supergiant VY Canis Majoris was made between 279 and 355 GHz with the Submillimeter Array. Two hundred twenty three spectral features from 19 molecules (not counting isotopic species of some of them) were observed, including the rotational spectra of TiO, TiO2, and AlCl for the first time in this source. The parameters and an atlas of all spectral features is presented. Observations of each line with a synthesized beam of ~0.9 arcsec, reveal the c...

  13. Millimeter Detection Of AlO (X2Σ+) In The Oxygen-rich Envelope Of VY Canis Majoris

    Science.gov (United States)

    Tenenbaum, Emily D.; Ziurys, L. M.

    2009-05-01

    A new circumstellar molecule, the radical AlO (X 2Σ+), has been detected toward the envelope of the oxygen-rich supergiant star VY Canis Majoris (VY CMa) via three rotational emission lines. The N = 7 → 6 and 6 → 5 features of AlO were observed at 1 mm using the Arizona Radio Observatory Submillimeter Telescope (ARO SMT) and the N = 4 → 3 line was detected at 2 mm using the ARO 12 m dish. All lines exhibit noticeable hyperfine broadening due to the I = 5/2 spin of the aluminum nucleus. Based on simulations of the line profiles, AlO most likely arises from the dust-acceleration zone in the spherical outflow of VY CMa, with a source size of θs 0.5''. Given this source size, the column density of AlO was found to be Ntot 2 × 1015 cm-2 for Trot 230 K, with a fractional abundance, relative to H2, of 10-8. Gas-phase thermodynamic equilibrium chemistry is the likely formation mechanism for AlO in VY CMa, but shocks may disrupt the condensation process into Al2O3, allowing AlO to survive 20 stellar radii. The detection of AlO in VY CMa is additional evidence of an active gas-phase refractory chemistry in oxygen-rich envelopes, and suggests such objects may be fruitful sources for other new oxide identifications.

  14. Exotic Metal Molecules in Oxygen-rich Envelopes: Detection of AlOH (X1Σ+) in VY Canis Majoris

    Science.gov (United States)

    Tenenbaum, E. D.; Ziurys, L. M.

    2010-03-01

    A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s-1, as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H2 was found to be ~1 × 10-7 for a source size of 0.26'' or 22 R* . In contrast, AlCl was not detected with f VY CMa is ~17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

  15. The Arizona Radio Observatory 1 mm Spectral Survey of IRC (plus)10216 and VY Canis Majoris (215-285 GHz)

    Science.gov (United States)

    Tenenbaum, E. D.; Dodd, J. L.; Milam, S. N.; Woolf, N. J.; Ziurys, L. M.

    2010-01-01

    A low noise (1(sigma) rms approx. 3 mK) 1. nun spectral survey (214.5-285.5 GHz) of the oxygen-rich supergiant VY Canis Majoris and the carbon-rich asymptotic giant branch star IRC +10216 has been conducted using the Arizona Radio Observatory's 10 m Submillimeter Telescope. Here the complete data set is presented. This study, carried out with a new ALMA-type receiver, marks the first continuous band scan of an O-rich circumstellar envelope, and the most sensitive survey to date of IRC +10216. In VY CMa, 130 distinct molecular lines were detected, 14 of which cannot be identified; in IRC +10216, 717 lines were observed, with 126 features remaining unidentified. In the 1 mm bands of VY CMa and IRC +10216, emission is present from 18 and 32 different chemical compounds, respectively, with 10 species common to both sources. Many narrow emission lines were observed in both circumstellar shells, arising from vibrationally excited molecules and from refractory-containing species. Line profiles in VY CMa also exhibit a variety of different shapes, caused by the complex, asymmetric outflow of this object. The survey highlights the fact that C-rich and O-rich circumstellar envelopes are chemically interesting, and both are sources of new interstellar molecules. The high number of unidentified lines and the unreliable, rest frequencies for known species such as NaCN indicate the need for additional laboratory spectroscopy studies.

  16. The Arizona Radio Observatory 1 mm Spectral Survey of IRC +10216 and VY Canis Majoris (215-285 GHz)

    Science.gov (United States)

    Tenenbaum, E. D.; Dodd, J. L.; Milam, S. N.; Woolf, N. J.; Ziurys, L. M.

    2010-10-01

    A low noise (1σ rms ~ 3 mK) 1 mm spectral survey (214.5-285.5 GHz) of the oxygen-rich supergiant VY Canis Majoris and the carbon-rich asymptotic giant branch star IRC +10216 has been conducted using the Arizona Radio Observatory's 10 m Submillimeter Telescope. Here the complete data set is presented. This study, carried out with a new ALMA-type receiver, marks the first continuous band scan of an O-rich circumstellar envelope, and the most sensitive survey to date of IRC +10216. In VY CMa, 130 distinct molecular lines were detected, 14 of which cannot be identified; in IRC +10216, 717 lines were observed, with 126 features remaining unidentified. In the 1 mm bands of VY CMa and IRC +10216, emission is present from 18 and 32 different chemical compounds, respectively, with 10 species common to both sources. Many narrow emission lines were observed in both circumstellar shells, arising from vibrationally excited molecules and from refractory-containing species. Line profiles in VY CMa also exhibit a variety of different shapes, caused by the complex, asymmetric outflow of this object. The survey highlights the fact that C-rich and O-rich circumstellar envelopes are chemically interesting, and both are sources of new interstellar molecules. The high number of unidentified lines and the unreliable rest frequencies for known species such as NaCN indicate the need for additional laboratory spectroscopy studies.

  17. THE ARIZONA RADIO OBSERVATORY 1 mm SPECTRAL SURVEY OF IRC +10216 AND VY CANIS MAJORIS (215-285 GHz)

    International Nuclear Information System (INIS)

    Tenenbaum, E. D.; Dodd, J. L.; Woolf, N. J.; Ziurys, L. M.; Milam, S. N.

    2010-01-01

    A low noise (1σ rms ∼ 3 mK) 1 mm spectral survey (214.5-285.5 GHz) of the oxygen-rich supergiant VY Canis Majoris and the carbon-rich asymptotic giant branch star IRC +10216 has been conducted using the Arizona Radio Observatory's 10 m Submillimeter Telescope. Here the complete data set is presented. This study, carried out with a new ALMA-type receiver, marks the first continuous band scan of an O-rich circumstellar envelope, and the most sensitive survey to date of IRC +10216. In VY CMa, 130 distinct molecular lines were detected, 14 of which cannot be identified; in IRC +10216, 717 lines were observed, with 126 features remaining unidentified. In the 1 mm bands of VY CMa and IRC +10216, emission is present from 18 and 32 different chemical compounds, respectively, with 10 species common to both sources. Many narrow emission lines were observed in both circumstellar shells, arising from vibrationally excited molecules and from refractory-containing species. Line profiles in VY CMa also exhibit a variety of different shapes, caused by the complex, asymmetric outflow of this object. The survey highlights the fact that C-rich and O-rich circumstellar envelopes are chemically interesting, and both are sources of new interstellar molecules. The high number of unidentified lines and the unreliable rest frequencies for known species such as NaCN indicate the need for additional laboratory spectroscopy studies.

  18. Interpretation of the line profiles of the 8 micron band of silicon monoxide from VY canis majoris

    International Nuclear Information System (INIS)

    Van Blerkom, D.; Xinjie, M.

    1982-01-01

    Observations of the vibration-rotation transitions of silicon monoxide from the expanding circumstellar envelope of VY Canis Majoris have previously been interpreted in terms of line formation in a thin shell of gas surrounding an opaque core of dust which emits a continuous spectrum. We show that the use of this model is the cause of the apparent displacement of the stellar velocity derived from the 8 μm lines by 14 km s -1 from the value based on the v = 0, J = 2→1 SiO line and on the midpoint of the OH maser emission. No such displacement occurs if a model of line formation is employed in which emission from the entire envelope contributes to the emergent profile. This eliminates the need to postulate asymmetries in the envelope and agrees with infrared continuum studies

  19. Interferometric Observations of the SiO High J Transition Maser associated with VY Canis Majoris with the Submillimeter Array

    Science.gov (United States)

    Shinnaga, H.; Moran, J. M.; Young, K. H.; Ho, P. T. P.

    2005-12-01

    We imaged the SiO maser emission of J=5-4 in the v=1 state associated with the peculiar red supergiant VY Canis Majoris using the partially completed Submillimeter Array. We identified seven maser components and measured the relative positions at sub-arcsecond scale in the high J transition for the first time. We have also measured the polarization of these maser components. The strongest maser feature has a linear polarization of ˜ 60%, and its direction of polarization is approximately aligned with the bipolar axis. Such a high degree of polarization suggests that radiative pumping is probably responsible for the maser inversion. Five of the other maser features have significant linear polarization.

  20. Distribution of SO_{2} and so in the Envelope of Vy-Canis Majoris: Insight Into Circumstellar Sulfur Chemistry

    Science.gov (United States)

    Adande, Gilles; Ziurys, L. M.

    2013-06-01

    Millimeter wave observations of SO_{2} and SO in the envelope of the O-rich supergiant VY-Canis Majoris have been conducted with the Submillimeter Telescope (SMT) of the Arizona Radio Observatory, between 210 and 290 GHz. A non LTE radiative transfer code has been written to fit the line profile of 22 lines of SO_{2} and 5 transitions of SO, and model their abundance and distribution within the circumstellar envelope. The rotational levels involved span a wide energy range, from 13 cm^{-1} to 104 cm^{-1} for SO_{2}, and 17 to 40 cm^{-1} for SO. The high number of transitions fitted provides strong constraints on the excitation conditions, hydrogen density and kinetic temperatures. The results will be discussed in relation to the formation processes and chemistry of these two species in O-rich molecular envelopes.

  1. High Resolution Near-IR Imaging of VY Canis Majoris with LBT / LMIRCam (2 - 5 μm)

    Science.gov (United States)

    Shenoy, Dinesh; Jones, T. J.; Humphreys, R. M.; LMIRCam Instrument Team

    2013-06-01

    HST imaging of the famous red hypergiant VY Canis Majoris shows a complex circumstellar reflection nebula indicative of multiple asymmetric ejection episodes. Constructing a more complete picture of the mass loss mechanism compels extending high resolution imaging of massive stars such as VY CMa into the near-infrared, where the mechanism for emission from circumstellar ejecta transitions from scattering to thermal. We present LBT/LMIRCam observations of VY CMa at Ks (2.2 μm), L' (3.8 μm) and M (4.9 μm) at sub-arcsecond resolution, comparable to the HST in the optical. The peculiar Southwest (SW) Clump, first identified as a highly reddened feature seen only at the longest wavelength (1 μm) in the HST images, appears bright in the three LMIRCam filters. The SW Clump is found to be optically thick at all three wavelengths. A silicate grain model yields a lower limit mass on the order of 7E-4 M⊙

  2. Millimeter Detection of AlO (X 2Σ+): Metal Oxide Chemistry in the Envelope of VY Canis Majoris

    Science.gov (United States)

    Tenenbaum, E. D.; Ziurys, L. M.

    2009-03-01

    A new circumstellar molecule, the radical AlO (X 2Σ+), has been detected toward the envelope of the oxygen-rich supergiant star VY Canis Majoris (VY CMa) using the Arizona Radio Observatory (ARO). The N = 7 → 6 and 6 → 5 rotational transitions of AlO at 268 and 230 GHz were observed at 1 mm using the ARO Submillimeter Telescope (SMT) and the N = 4 → 3 line was detected at 2 mm using the ARO 12 m telescope. Based on the shape of the line profiles, AlO most likely arises from the dust-forming region in the spherical outflow of VY CMa, as opposed to the blue or redshifted winds, with a source size of θ s ~ 0farcs5. Given this source size, the column density of AlO was found to be N tot ~ 2 × 1015 cm-2 for T rot ~ 230 K, with a fractional abundance, relative to H2, of ~10-8. Gas-phase thermodynamic equilibrium chemistry is the likely formation mechanism for AlO in VY CMa, but either shocks disrupt the condensation process into Al2O3, or chemical "freezeout" occurs. The species therefore survives further into the circumstellar envelope to a radius of r ~ 20 R *. The detection of AlO in VY CMa is additional evidence of an active gas-phase refractory chemistry in oxygen-rich envelopes, and suggests such objects may be fruitful sources for other new oxide identifications.

  3. Millimeter Detection of AlO (X^2 Σ ^+): Metal Oxide Chemistry in the Envelope of VY Canis Majoris

    Science.gov (United States)

    Tenenbaum, E. D.; Ziurys, L. M.

    2009-06-01

    A new circumstellar molecule, the radical AlO (X^2 Σ ^+), has been detected toward the envelope of the oxygen-rich supergiant star VY Canis Majoris (VY CMa) using the Arizona Radio Observatory (ARO). The N = 7 → 6 and 6 → 5 rotational transitions of AlO at 268 and 230 GHz were observed at 1 mm using the ARO Submillimeter Telescope (SMT) and the N = 4 → 3 line was detected at 2 mm using the ARO 12 m. Based on the shape of the line profiles, AlO most likely arises from the dust-forming region in the spherical outflow of VY CMa, as opposed to the blue- or red-shifted winds, with a source size of θ_s ˜ 0.5^''. Given this source size, the column density of AlO was found to be N_{tot} ˜ 2 × 10^{15} cm^{-2} for T_{rot} ˜ 230 K, with a fractional abundance, relative to H_2, of ˜ 10^{-8}. Gas-phase thermodynamic equilibrium chemistry is the likely formation mechanism for AlO in VY CMa, but shocks may disrupt the condensation process into Al_2O_3, allowing AlO to survive to a radius of ˜ 20 R_*. The detection of AlO in VY CMa is additional evidence of an active gas-phase refractory chemistry in oxygen-rich envelopes, and suggests such objects may be fruitful sources for other new oxide identifications.

  4. MILLIMETER DETECTION OF AlO (X 2Σ+): METAL OXIDE CHEMISTRY IN THE ENVELOPE OF VY CANIS MAJORIS

    International Nuclear Information System (INIS)

    Tenenbaum, E. D.; Ziurys, L. M.

    2009-01-01

    A new circumstellar molecule, the radical AlO (X 2 Σ + ), has been detected toward the envelope of the oxygen-rich supergiant star VY Canis Majoris (VY CMa) using the Arizona Radio Observatory (ARO). The N = 7 → 6 and 6 → 5 rotational transitions of AlO at 268 and 230 GHz were observed at 1 mm using the ARO Submillimeter Telescope (SMT) and the N = 4 → 3 line was detected at 2 mm using the ARO 12 m telescope. Based on the shape of the line profiles, AlO most likely arises from the dust-forming region in the spherical outflow of VY CMa, as opposed to the blue or redshifted winds, with a source size of θ s ∼ 0.''5. Given this source size, the column density of AlO was found to be N tot ∼ 2 x 10 15 cm -2 for T rot ∼ 230 K, with a fractional abundance, relative to H 2 , of ∼10 -8 . Gas-phase thermodynamic equilibrium chemistry is the likely formation mechanism for AlO in VY CMa, but either shocks disrupt the condensation process into Al 2 O 3 , or chemical 'freezeout' occurs. The species therefore survives further into the circumstellar envelope to a radius of r ∼ 20 R * . The detection of AlO in VY CMa is additional evidence of an active gas-phase refractory chemistry in oxygen-rich envelopes, and suggests such objects may be fruitful sources for other new oxide identifications.

  5. EXOTIC METAL MOLECULES IN OXYGEN-RICH ENVELOPES: DETECTION OF AlOH (X1Σ+) IN VY CANIS MAJORIS

    International Nuclear Information System (INIS)

    Tenenbaum, E. D.; Ziurys, L. M.

    2010-01-01

    A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris (VY CMa), an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope, while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths of 16-23 km s -1 , as found for NaCl in this source, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H 2 was found to be ∼1 x 10 -7 for a source size of 0.26'' or 22 R * . In contrast, AlCl was not detected with f ≤ 5 x 10 -8 . AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is ∼17. Therefore, AlOH appears to be the dominant gas-phase molecular carrier of aluminum in this oxygen-rich shell. Local thermodynamic equilibrium calculations predict that the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides. The apparent predominance of aluminum-bearing molecules in VY CMa may reflect proton addition processes in H-shell burning.

  6. ADAPTIVE OPTICS IMAGING OF VY CANIS MAJORIS AT 2-5 μm WITH LBT/LMIRCam

    Energy Technology Data Exchange (ETDEWEB)

    Shenoy, Dinesh P.; Jones, Terry J.; Humphreys, Roberta M. [Minnesota Institute for Astrophysics, University of Minnesota, 116 Church Street SE, Minneapolis, MN 55455 (United States); Marengo, Massimo [Department of Physics, Iowa State University, Ames, IA 50011 (United States); Leisenring, Jarron M. [Institute for Astronomy, ETH, Wolfgang-Pauli-Strasse 27, 8093 Zurich (Switzerland); Nelson, Matthew J.; Wilson, John C.; Skrutskie, Michael F. [Department of Astronomy, University of Virginia, 530 McCormick Road, Charlottesville, VA 22904 (United States); Hinz, Philip M.; Hoffmann, William F.; Bailey, Vanessa; Skemer, Andrew; Rodigas, Timothy; Vaitheeswaran, Vidhya, E-mail: shenoy@astro.umn.edu [Steward Observatory, University of Arizona, 933 N. Cherry Avenue, Tucson, AZ 85721 (United States)

    2013-10-01

    We present adaptive optics images of the extreme red supergiant VY Canis Majoris in the K{sub s} , L', and M bands (2.15-4.8 μm) made with LMIRCam on the Large Binocular Telescope. The peculiar ''Southwest Clump'' previously imaged from 1 to 2.2 μm appears prominently in all three filters. We find its brightness is due almost entirely to scattering, with the contribution of thermal emission limited to at most 25%. We model its brightness as optically thick scattering from silicate dust grains using typical size distributions. We find a lower limit mass for this single feature of 5 × 10{sup –3} M {sub ☉} to 2.5 × 10{sup –2} M {sub ☉} depending on the assumed gas-to-dust ratio. The presence of the Clump as a distinct feature with no apparent counterpart on the other side of the star is suggestive of an ejection event from a localized region of the star and is consistent with VY CMa's history of asymmetric high-mass-loss events.

  7. Exotic Metal Molecules in Oxygen-Rich Envelopes: Detection of AlOH (X1Σ^+) in VY Canis Majoris

    Science.gov (United States)

    Tenenbaum, E. D.; Ziurys, L. M.

    2010-06-01

    A new interstellar molecule, AlOH, has been detected toward the envelope of VY Canis Majoris, an oxygen-rich red supergiant. Three rotational transitions of AlOH were observed using the facilities of the Arizona Radio Observatory (ARO). The J = 9 → 8 and J = 7 → 6 lines at 1 mm were measured with the ARO Submillimeter Telescope (SMT), while the J = 5 → 4 transition at 2 mm was observed with the ARO 12 m antenna on Kitt Peak. The AlOH spectra exhibit quite narrow line widths, indicating that the emission arises from within the dust acceleration zone of the central circumstellar outflow. From a radiative transfer analysis, the abundance of AlOH relative to H_2 was found to be 1x10-7 for a source size of 0.26'' or 22 R_*. AlOH is likely formed just beyond the photosphere via thermodynamic equilibrium chemistry, and then disappears due to dust condensation. The AlOH/AlO abundance ratio found in VY CMa is ˜17. LTE calculations predict the monohydroxides should be the major carriers of Al, Ca, and Mg in O-rich envelopes, as opposed to the oxides or halides.

  8. ADAPTIVE OPTICS IMAGING OF VY CANIS MAJORIS AT 2-5 μm WITH LBT/LMIRCam

    International Nuclear Information System (INIS)

    Shenoy, Dinesh P.; Jones, Terry J.; Humphreys, Roberta M.; Marengo, Massimo; Leisenring, Jarron M.; Nelson, Matthew J.; Wilson, John C.; Skrutskie, Michael F.; Hinz, Philip M.; Hoffmann, William F.; Bailey, Vanessa; Skemer, Andrew; Rodigas, Timothy; Vaitheeswaran, Vidhya

    2013-01-01

    We present adaptive optics images of the extreme red supergiant VY Canis Majoris in the K s , L', and M bands (2.15-4.8 μm) made with LMIRCam on the Large Binocular Telescope. The peculiar ''Southwest Clump'' previously imaged from 1 to 2.2 μm appears prominently in all three filters. We find its brightness is due almost entirely to scattering, with the contribution of thermal emission limited to at most 25%. We model its brightness as optically thick scattering from silicate dust grains using typical size distributions. We find a lower limit mass for this single feature of 5 × 10 –3 M ☉ to 2.5 × 10 –2 M ☉ depending on the assumed gas-to-dust ratio. The presence of the Clump as a distinct feature with no apparent counterpart on the other side of the star is suggestive of an ejection event from a localized region of the star and is consistent with VY CMa's history of asymmetric high-mass-loss events

  9. Adaptive Optics Imaging of VY Canis Majoris at 2-5 μm with LBT/LMIRCam

    Science.gov (United States)

    Shenoy, Dinesh P.; Jones, Terry J.; Humphreys, Roberta M.; Marengo, Massimo; Leisenring, Jarron M.; Nelson, Matthew J.; Wilson, John C.; Skrutskie, Michael F.; Hinz, Philip M.; Hoffmann, William F.; Bailey, Vanessa; Skemer, Andrew; Rodigas, Timothy; Vaitheeswaran, Vidhya

    2013-10-01

    We present adaptive optics images of the extreme red supergiant VY Canis Majoris in the Ks , L', and M bands (2.15-4.8 μm) made with LMIRCam on the Large Binocular Telescope. The peculiar "Southwest Clump" previously imaged from 1 to 2.2 μm appears prominently in all three filters. We find its brightness is due almost entirely to scattering, with the contribution of thermal emission limited to at most 25%. We model its brightness as optically thick scattering from silicate dust grains using typical size distributions. We find a lower limit mass for this single feature of 5 × 10-3 M ⊙ to 2.5 × 10-2 M ⊙ depending on the assumed gas-to-dust ratio. The presence of the Clump as a distinct feature with no apparent counterpart on the other side of the star is suggestive of an ejection event from a localized region of the star and is consistent with VY CMa's history of asymmetric high-mass-loss events. The LBT is an international collaboration among institutions in the United States, Italy, and Germany. LBT Corporation partners are: The University of Arizona on behalf of the Arizona university system; Istituto Nazionale di Astrofisica, Italy; LBT Beteiligungsgesellschaft, Germany, representing the Max-Planck Society, the Astrophysical Institute Potsdam, and Heidelberg University; The Ohio State University; and The Research Corporation, on behalf of The University of Notre Dame, University of Minnesota, and University of Virginia.

  10. Sulfur chemistry in the envelope of VY Canis Majoris: Detailed analysis of SO and SO2 emission

    International Nuclear Information System (INIS)

    Adande, G. R.; Edwards, J. L.; Ziurys, L. M.

    2013-01-01

    Detailed radiative transfer modeling has been carried out for SO 2 and SO originating in the envelope of the O-rich supergiant star VY Canis Majoris (VY CMa). A total of 27 transitions of SO 2 and 7 transitions of SO lying in the energy range 3.0-138.2 cm –1 were analyzed using a new non-LTE radiative transfer code that incorporates non-spherical geometries. The spectra were primarily obtained from the Arizona Radio Observatory (ARO) 1 mm spectral survey of VY CMa, conducted with the Submillimeter Telescope; additional lines were measured with the ARO 12 m antenna at 2 and 3 mm. SO 2 and SO were found to arise from five distinct outflows within the envelope, four which are asymmetric with respect to the star. Three flows arise from high-velocity red-shifted material, one from a blue-shifted wind, and the final from a classic 'spherical' expansion. In the spherical component, the peak fractional abundance, relative to H 2 , of both molecules is f ∼ 2.5 × 10 –7 at r ∼ 25 R * , and steadily decreases outward. SO 2 appears to be a 'parent' molecule, formed near the stellar photosphere. In the asymmetric outflows, both SO and SO 2 are more prominent at large stellar radii in dense (10 6 -10 7 cm –3 ), clumpy material, achieving their maximum abundance between 200 and 600 R * with f ∼ 3.0 × 10 –8 -1.5 × 10 –7 . These results suggest that in the collimated outflows, both species are either produced by shock chemistry or are remnant inner shell material swept up in the high-velocity winds.

  11. Sulfur Chemistry in the Envelope of VY Canis Majoris: Detailed Analysis of SO and SO2 Emission

    Science.gov (United States)

    Adande, G. R.; Edwards, J. L.; Ziurys, L. M.

    2013-11-01

    Detailed radiative transfer modeling has been carried out for SO2 and SO originating in the envelope of the O-rich supergiant star VY Canis Majoris (VY CMa). A total of 27 transitions of SO2 and 7 transitions of SO lying in the energy range 3.0-138.2 cm-1 were analyzed using a new non-LTE radiative transfer code that incorporates non-spherical geometries. The spectra were primarily obtained from the Arizona Radio Observatory (ARO) 1 mm spectral survey of VY CMa, conducted with the Submillimeter Telescope; additional lines were measured with the ARO 12 m antenna at 2 and 3 mm. SO2 and SO were found to arise from five distinct outflows within the envelope, four which are asymmetric with respect to the star. Three flows arise from high-velocity red-shifted material, one from a blue-shifted wind, and the final from a classic "spherical" expansion. In the spherical component, the peak fractional abundance, relative to H2, of both molecules is f ~ 2.5 × 10-7 at r ~ 25 R *, and steadily decreases outward. SO2 appears to be a "parent" molecule, formed near the stellar photosphere. In the asymmetric outflows, both SO and SO2 are more prominent at large stellar radii in dense (106-107 cm-3), clumpy material, achieving their maximum abundance between 200 and 600 R * with f ~ 3.0 × 10-8-1.5 × 10-7. These results suggest that in the collimated outflows, both species are either produced by shock chemistry or are remnant inner shell material swept up in the high-velocity winds.

  12. Interferometric Observation of the Highly Polarized SiO Maser Emission from the v = 1, J = 5-4 Transition Associated with VY Canis Majoris

    OpenAIRE

    Shinnaga, Hiroko; Moran, James M.; Young, Ken Harbour; Ho, Paul T. P.

    2004-01-01

    We used the Submillimeter Array to image the SiO maser emission in the $v=1$, \\$J=5-4$ transition associated with the peculiar red supergiant VY Canis Majoris. We identified seven maser components and measured their relative positions and linear polarization properties. Five of the maser components are coincident to within about 150 mas ($\\sim$ 200 AU at the distance of 1.5 kpc); most of them may originate in the circumstellar envelope at a radius of about 50 mas from the star along with the ...

  13. Hubble Space Telescope Imaging of the Mass-losing Supergiant VY Canis Majoris

    Science.gov (United States)

    Kastner, Joel H.; Weintraub, David A.

    1998-04-01

    The highly luminous M supergiant VY CMa is a massive star that appears to be in its final death throes, losing mass at high rate en route to exploding as a supernova. Subarcsecond-resolution optical images of VY CMa, obtained with the Faint Object Camera (FOC) aboard the Hubble Space Telescope, vividly demonstrate that mass loss from VY CMa is highly anisotropic. In the FOC images, the optical ``star'' VY CMa constitutes the bright, well-resolved core of an elongated reflection nebula. The imaged nebula is ~3" (~4500 AU) in extent and is clumpy and highly asymmetric. The images indicate that the bright core, which lies near one edge of the nebula, is pure scattered starlight. We conclude that at optical wavelengths VY CMa is obscured from view along our line of sight by its own dusty envelope. The presence of the extended reflection nebula then suggests that this envelope is highly flattened and/or that the star is surrounded by a massive circumstellar disk. Such axisymmetric circumstellar density structure should have profound effects on post-red supergiant mass loss from VY CMa and, ultimately, on the shaping of the remnant of the supernova that will terminate its post-main-sequence evolution.

  14. COMPARATIVE SPECTRA OF OXYGEN-RICH VERSUS CARBON-RICH CIRCUMSTELLAR SHELLS: VY CANIS MAJORIS AND IRC +10216 AT 215-285 GHz

    International Nuclear Information System (INIS)

    Tenenbaum, E. D.; Dodd, J. L.; Woolf, N. J.; Ziurys, L. M.; Milam, S. N.

    2010-01-01

    A sensitive (1σ rms at 1 MHz resolution ∼3 mK) 1 mm spectral line survey (214.5-285.5 GHz) of VY Canis Majoris (VY CMa) and IRC +10216 has been conducted to compare the chemistries of oxygen- and carbon-rich circumstellar envelopes. This study was carried out using the Submillimeter Telescope of the Arizona Radio Observatory with a new Atacama Large Millimeter Array type receiver. This survey is the first to chemically characterize an O-rich circumstellar shell at millimeter wavelengths. In VY CMa, 128 emission features were detected arising from 18 different molecules; and in IRC +10216, 720 lines were observed, assigned to 32 different species. The 1 mm spectrum of VY CMa is dominated by SO 2 and SiS; in IRC +10216, C 4 H and SiC 2 are the most recurrent species. Ten molecules were common to both sources: CO, SiS, SiO, CS, CN, HCN, HNC, NaCl, PN, and HCO + . Sulfur plays an important role in VY CMa, but saturated/unsaturated carbon dominates the molecular content of IRC +10216, producing CH 2 NH, for example. Although the molecular complexity of IRC +10216 is greater, VY CMa supports a unique 'inorganic' chemistry leading to the oxides PO, AlO, and AlOH. Only diatomic and triatomic compounds were observed in VY CMa, while species with four or more atoms are common in IRC +10216, reflecting carbon's ability to form multiple strong bonds, unlike oxygen. In VY CMa, a new water maser (v 2 = 2) has been found, as well as vibrationally excited NaCl. Toward IRC +10216, vibrationally excited CCH was detected for the first time.

  15. Comparative Spectra of Oxygen-rich Versus Carbon-rich Circumstellar Shells: VY Canis Majoris and IRC +10216 at 215-285 GHz

    Science.gov (United States)

    Tenenbaum, E. D.; Dodd, J. L.; Milam, S. N.; Woolf, N. J.; Ziurys, L. M.

    2010-09-01

    A sensitive (1σ rms at 1 MHz resolution ~3 mK) 1 mm spectral line survey (214.5-285.5 GHz) of VY Canis Majoris (VY CMa) and IRC +10216 has been conducted to compare the chemistries of oxygen- and carbon-rich circumstellar envelopes. This study was carried out using the Submillimeter Telescope of the Arizona Radio Observatory with a new Atacama Large Millimeter Array type receiver. This survey is the first to chemically characterize an O-rich circumstellar shell at millimeter wavelengths. In VY CMa, 128 emission features were detected arising from 18 different molecules; and in IRC +10216, 720 lines were observed, assigned to 32 different species. The 1 mm spectrum of VY CMa is dominated by SO2 and SiS; in IRC +10216, C4H and SiC2 are the most recurrent species. Ten molecules were common to both sources: CO, SiS, SiO, CS, CN, HCN, HNC, NaCl, PN, and HCO+. Sulfur plays an important role in VY CMa, but saturated/unsaturated carbon dominates the molecular content of IRC +10216, producing CH2NH, for example. Although the molecular complexity of IRC +10216 is greater, VY CMa supports a unique "inorganic" chemistry leading to the oxides PO, AlO, and AlOH. Only diatomic and triatomic compounds were observed in VY CMa, while species with four or more atoms are common in IRC +10216, reflecting carbon's ability to form multiple strong bonds, unlike oxygen. In VY CMa, a new water maser (v 2 = 2) has been found, as well as vibrationally excited NaCl. Toward IRC +10216, vibrationally excited CCH was detected for the first time.

  16. Comparative Spectra of Oxygen-Rich Versus Carbon-Rich Circumstellar Shells: VY Canis Majoris and IRC(plus)10216 at 215-285 GHz

    Science.gov (United States)

    Tenebaum, E. D.; Dodd, J. L.; Milam, S. N.; Woolf, N. J.; Ziurys, L. M.

    2010-01-01

    A sensitive (1sigma rms at 1 MHz resolution approx.3 mK) 1 mm spectral line survey (214.5-285.5 GHz) of VY Canis Majoris (VY CMa) and IRC +10216 has been conducted to compare the chemistries of oxygen- and carbon-rich circumstellar envelopes. This study was carried out using the Submillimeter Telescope of the Arizona Radio Observatory with a new Atacama Large Millimeter Array type receiver. This survey is the first to chemically characterize an O-rich circumstellar shell at millimeter wavelengths. In VY CMa, 128 emission features were detected arising from 18 different molecules; and in IRC +10216, 720 lines were observed, assigned to 32 different species. The 1 mm spectrum of VY CMa is dominated by SO, and SiS; in IRC +10216, C4H and SiC2 are the most recurrent species. Ten molecules were common to both sources: CO, SiS, SiO, CS, CN, HCN, HNC, NaCl, PN, and HCO(+). Sulfur plays an important role in VY CMa, but saturated/ unsaturated carbon dominates the molecular content of IRC +102.16, producing CH2NH, for example. Although the molecular complexity of IRC +10216 is greater, VY CMa supports a unique "inorganic" chemistry leading to the oxides PO, AlO, and AlOH. Only diatomic and triatomic compounds were observed in VY CMa, while species with four or more atoms are common in IRC +10216, reflecting carbon's ability to form multiple strong bonds, unlike oxygen. In VY CMa, a new water maser (v2 = 2) has been found, as well as vibrationally excited NaCl. Toward IRC +10216, vibrationally excited CCH was detected for the first time.

  17. Radio Photosphere and Mass-Loss Envelope of VY Canis Majoris

    Science.gov (United States)

    Lipscy, S. J.; Jura, M.; Reid, M. J.

    2005-06-01

    We have used the VLA to detect emission from the supergiant VY CMa at radio wavelengths and have constructed 3000-4500 K isothermal outer atmospheres constrained by the data. These models produce a radio photosphere at 1.5-2 R*. An extrapolation of the model can account for the observed total mass-loss rate of the star. We also present mid-infrared imaging of the supergiant which suggests that warm dust is extended in the same direction as the near-infrared reflection nebula around VY CMa. The origin of the asymmetries in the outflow remains an unsolved problem.

  18. Geometry of VY Canis Majoris derived from SiO maser lines

    International Nuclear Information System (INIS)

    Van Blerkom, D.; Auer, L.

    1976-01-01

    A radiation reveals transfer calculation reveals that the SiO maser lines observed in the spectrum of VY CMa are formed in a rotating equatorial disk seen nearly edge-on. Other geometries are considered and eliminated. It is suggested that the SiO lines of NML Cyg also show evidence that they are formed in a disk

  19. The 1 mm spectrum of VY Canis Majoris: Chemistry in an O-rich envelope

    Science.gov (United States)

    Tenenbaum, Emily D.; Milam, Stefanie N.; Apponi, Aldo J.; Woolf, Neville J.; Ziurys, Lucy M.; Schöier, Fredrik L.

    2008-10-01

    We present preliminary results of an unbiased spectral survey at 1 mm of the oxygen-rich supergiant, VY CMa. A number of exotic molecules have been detected, including NaCl and PO, and a relatively rich organic chemistry is observed. Results of the survey will be compared with carbon-rich stars.

  20. CO observations of a molecular cloud complex associated with the bright rim near VY Canis Majoris

    International Nuclear Information System (INIS)

    Lada, C.J.; Reid, M.J.

    1978-01-01

    Extensive CO observations of a large molecular cloud complex (approx. 15 pc) associated with a bright rim near the peculiar star VY CMa are presented. CO emission peaks in a region along and adjacent to the bright rim which forms the western border of the cloud complex. This emission abruptly decreases across the bright rim, and this decrease suggests a physical association of the rim with the cloud. The molecular complex is found to consist of two clouds which have different radial velocities and physical properties. The possibility that these two clouds may be in near-collision is discussed. The physical association of the bright rim with the cloud complex indicates that the clouds are at the same distance, 1.5 kpc, as the stars which excite the rim. Since VY CMa appears to be located at the tip of the bright rim and has a velocity similar to that of the molecular cloud complex and the stars of the cluster NGC 2362, it is concluded that VY CMa is also at the same distance. The resulting luminosity of VY CMa (5 x 10 5 L sub solar) indicates that the star is very massive, and places constraints on interpretation of its evolutionary state. 5 figures, 2 tables

  1. A geometrical model of VY Canis Majoris for SiO maser lines

    International Nuclear Information System (INIS)

    Zhou Zhen-Pu; Kaifu, N.

    1984-01-01

    A new geometrical model of VY CMa is proposed to explain the three-peaked spectra of transition upsilon=1,2 J=1-0 of SiO maser emission. In this model the circumstellar envelope of VY CMa is a rotating disk of gas and dust seen nearly edge-on. The disk consists of two regions: a decelerated steady stream near the photosphere of the star and an accelerated one further away. Other geometries are discussed and eliminated. Calculated profiles of SiO maser lines fit well the observations. It is possible to explain the three-peaked profiles of SiO maser lines emitted by NML Cyg, RR Aql, NML Tau, etc. (orig.)

  2. MERLIN observations of water maser proper motions in VY Canis Majoris

    Science.gov (United States)

    Richards, A. M. S.; Yates, J. A.; Cohen, R. J.

    1998-09-01

    MERLIN observations of the 22-GHz water masers in the circumstellar envelope of the supergiant VY CMa show an ellipsoidal distribution with a maximum extent of 700 mas east-west and 400 mas north-south. Comparison with observations made nine years earlier shows that the majority of maser features have survived and show proper motions throughout the region. The mean change in position is 28 mas and the proper motions are generally directed away from the assumed stellar position, and tend to be larger for features at greater projected distances. If the H_2O maser region is modelled as a partially filled thick spherical shell, and VY CMa is at a distance of 1.5 kpc, then the proper motion velocities in the direction of expansion are between 8kms^-1 at a distance of 75 mas from the assumed stellar position and 32kms^-1 at 360 mas. These velocities are consistent with the H_2O maser spectral line velocities which correspond to a maximum expansion velocity of 36kms^-1 at 400 mas from the assumed stellar position. These observations are consistent with radiation pressure on dust providing the force to accelerate the stellar wind as it passes through the H_2O maser shell. The H_2O maser region is elongated in the same direction as the dusty nebula around VY CMa. The water masers illuminate the small-scale dynamics and clumpiness which show the role of dust in driving the outflow. The overall ellipsoidal shape may be due to properties of the dust, such as its behaviour in the stellar magnetic field, or to interaction between the wind and circumstellar material. Maser monitoring also shows the difference between changes on the time-scale of stellar variability (a few years) and possible stages in the evolution of VY CMa to its likely fate as a supernova.

  3. ALMA observations of TiO2 around VY Canis Majoris

    Science.gov (United States)

    De Beck, E.; Vlemmings, W.; Muller, S.; Black, J. H.; O'Gorman, E.; Richards, A. M. S.; Baudry, A.; Maercker, M.; Decin, L.; Humphreys, E. M.

    2015-08-01

    Context. Titanium dioxide, TiO2, is a refractory species that could play a crucial role in the dust-condensation sequence around oxygen-rich evolved stars. To date, gas phase TiO2 has been detected only in the complex environment of the red supergiant VY CMa. Aims: We aim to constrain the distribution and excitation of TiO2 around VY CMa in order to clarify its role in dust formation. Methods: We analyse spectra and channel maps for TiO2 extracted from ALMA science verification data. Results: We detect 15 transitions of TiO2, and spatially resolve the emission for the first time. The maps demonstrate a highly clumpy, anisotropic outflow in which the TiO2 emission likely traces gas exposed to the stellar radiation field. An accelerating bipolar-like structure is found, oriented roughly east-west, of which the blue component runs into and breaks up around a solid continuum component. A distinct tail to the south-west is seen for some transitions, consistent with features seen in the optical and near-infrared. Conclusions: We find that a significant fraction of TiO2 remains in the gas phase outside the dust-formation zone and suggest that this species might play only a minor role in the dust-condensation process around extreme oxygen-rich evolved stars like VY CMa. Appendix A is available in electronic form at http://www.aanda.org

  4. Identification of Phosphorus Monoxide (X2Πr) in VY Canis Majoris: Detection of the First PO Bond in Space

    Science.gov (United States)

    Tenenbaum, E. D.; Woolf, N. J.; Ziurys, L. M.

    2007-09-01

    A new interstellar molecule, PO (X2Πr), has been detected toward the envelope of the oxygen-rich supergiant star VY Canis Majoris (VY CMa) using the Submillimeter Telescope of the Arizona Radio Observatory. The J=5.5-->4.5 and J=6.5-->5.5 rotational transitions of PO at 240 and 284 GHz were observed, each of which consisted of well-defined lambda-doublets. The line profiles are roughly parabolic in shape, analogous to PN, and suggest that this species arises from the spherical wind in VY CMa, as opposed to the collimated blue- and redshifted outflows. Comparison of line intensities indicates that PO arises from a confined source roughly 1" in extent, with a column density of Ntot ~= 2.8 × 1015 cm-2, which corresponds to a fractional abundance of f~9×10-8, relative to H2. Consequently, PO and PN have similar concentrations in VY CMa, a result not predicted by either LTE or kinetic models of circumstellar chemistry. These phosphorus compounds may arise from shock-induced reactions in this active envelope. Phosphorus monoxide is the first interstellar molecule detected that contains a PO bond, a moiety essential in biochemical compounds. It is also the first new species to be identified in an oxygen-rich, as opposed to a carbon-rich, circumstellar envelope.

  5. The eight micron band of silicon monoxide in the expanding cloud around VY Canis Majoris

    International Nuclear Information System (INIS)

    Geballe, T.R.; Lacy, J.H.; Beck, S.C.

    1978-01-01

    Observations of vibration-rotation transitions of silicon monoxide in VY CMa show that the lines originate in accelerating, expanding, and cool (600 K) layers of a circumstellar cloud at a distance of roughly 0.15 minutes from the central star. The central stellar velocity, as estimated from observed SiO P Cygni line profiles, is somewhat redshifted from the midpoint of the maser emission features. Most of the silicon is proabably in the form of dust grains. The isotopic ratios of silicon are nearly terrestrial

  6. The 8 micron band of silicon monoxide in the expanding cloud around VY Canis Majoris

    Science.gov (United States)

    Geballe, T. R.; Lacy, J. H.; Beck, S. C.

    1979-01-01

    Observations of vibration-rotation transitions of silicon monoxide in VY CMa show that the lines originate in accelerating, expanding, and cool (about 600 K) layers of a circumstellar cloud at a distance of approximately 0.15 arcsec from the central star. The central stellar velocity, as estimated from observed SiO P Cygni line profiles, is somewhat redshifted from the midpoint of the maser emission features. Most of the silicon is probably in the form of dust grains. The isotopic ratios of silicon are nearly terrestrial.

  7. The eight micron band of silicon monoxide in the expanding cloud around VY Canis Majoris

    Science.gov (United States)

    Geballe, T. R.; Lacy, J. H.; Beck, S. C.

    1978-01-01

    Observations of vibration-rotation transitions of silicon monoxide in VY CMa show that the lines originate in accelerating, expanding, and cool (600 K) layers of a circumstellar cloud at a distance of roughly 0.15 minutes from the central star. The central stellar velocity, as estimated from observed SiO P Cygni line profiles, is somewhat redshifted from the midpoint of the maser emission features. Most of the silicon is probably in the form of dust grains. The isotopic ratios of silicon are nearly terrestrial.

  8. Radiative transfer in gray circumstellar dust envelopes: VY Canis Majoris revisited

    International Nuclear Information System (INIS)

    Schwartz, R.D.

    1975-01-01

    The circumstellar dust model for VY CMa proposed by Herbig is reinvestigated using a generalized form of Huang's theory of radiative transfer. The resultant envelope parameters and the emergent energy distribution are found to be insensitive to the choice of Eddington factor for a given envelope inner boundary temperature. Observed fluxes from 0.43 to 74 μ are incorporated into the model, and problems relating to grain emissivity for lambda>30 μ and grain survival at the indicated inner boundary temperature of 1855degreeK are discussed

  9. Submillimeter vibrationally excited water emission from the peculiar red supergiant VY Canis Majoris

    Science.gov (United States)

    Menten, K. M.; Philipp, S. D.; Güsten, R.; Alcolea, J.; Polehampton, E. T.; Brünken, S.

    2006-08-01

    Context: .Vibrationally excited emission from the SiO and H2O molecules probes the innermost circumstellar envelopes of oxygen-rich red giant and supergiant stars. VY CMa is the most prolific known emission source in these molecules. Aims: .Observations were made to search for rotational lines in the lowest vibrationally excited state of H2O. Methods: .The APEX telescope was used for observations of H2O lines at frequencies around 300 GHz. Results: .Two vibrationally excited H2O lines were detected, a third one could not be found. In one of the lines we find evidence for weak maser action, similar to known (sub)millimeter ν2 = 1 lines. We find that the other line's intensity is consistent with thermal excitation by the circumstellar infrared radiation field. Several SiO lines were detected together with the H2O lines.

  10. Bringing VY Canis Majoris Down to Size: An Improved Determination of Its Effective Temperature

    Science.gov (United States)

    Massey, Philip; Levesque, Emily M.; Plez, Bertrand

    2006-08-01

    The star VY CMa is a late-type M supergiant with many peculiarities, mostly related to the intense circumstellar environment due to the star's high mass-loss rate. Claims have been made that would imply that this star is considerably more luminous (L~5×105 Lsolar) and larger (R~2800 Rsolar) than other Galactic red supergiants (RSGs). Indeed, such a location in the H-R diagram would be well within the ``Hayashi forbidden zone,'' where stars cannot be in hydrostatic equilibrium. These extraordinary properties, however, rest on an assumed effective temperature of 2800-3000 K, far cooler than recent work has shown RSGs to be. To obtain a better estimate, we fit newly obtained spectrophotometry in the optical and NIR with the same MARCS models used for our recent determination of the physical properties of other RSGs; we also use V-K and V-J from the literature to derive an effective temperature. We find that the star likely has a temperature of 3650 K, a luminosity L~6×104 Lsolar, and a radius of ~600 Rsolar. These values are consistent with VY CMa being an ordinary, evolved 15 Msolar RSG and agree well with the Geneva evolutionary tracks. We find that the circumstellar dust region has a temperature of 760 K, and an effective radius of ~130 AU, if spherical geometry is assumed for the latter. What causes this star to have such a high mass loss and large variations in brightness (but with little change in color) remains a mystery at present, although we speculate that perhaps this star and NML Cyg are simply normal RSGs caught during an unusually unstable time.

  11. The Last Gasps of VY Canis Majoris: Aperture Synthesis and Adaptive Optics Imagery

    Science.gov (United States)

    Monnier, J. D.; Tuthill, P. G.; Lopez, B.; Cruzalebes, P.; Danchi, W. C.; Haniff, C. A.

    1999-02-01

    We present new observations of the red supergiant VY CMa at 1.25, 1.65, 2.26, 3.08, and 4.8 μm. Two complementary observational techniques were utilized: nonredundant aperture masking on the 10 m Keck I telescope, yielding images of the innermost regions at unprecedented resolution, and adaptive optics imaging on the ESO 3.6 m telescope at La Silla, attaining an extremely high (~105) peak-to-noise dynamic range over a wide field. For the first time the inner dust shell has been resolved in the near-infrared to reveal a one-sided extension of circumstellar emission within 0.1" (~15 R*) of the star. The line-of-sight optical depths of the circumstellar dust shell at 1.65, 2.26, and 3.08 μm have been estimated to be 1.86+/-0.42, 0.85+/-0.20, and 0.44+/-0.11, respectively. These new results allow the bolometric luminosity of VY CMa to be estimated independent of the dust shell geometry, yielding L*~2×105 Lsolar. A variety of dust condensations, including a large scattering plume and a bow-shaped dust feature, were observed in the faint, extended nebula up to 4" from the central source. While the origin of the nebulous plume remains uncertain, a geometrical model is developed assuming the plume is produced by radially driven dust grains forming at a rotating flow insertion point with a rotational period between 1200 and 4200 yr, which is perhaps the stellar rotational period or the orbital period of an unseen companion.

  12. ALMA sub-mm maser and dust distribution of VY Canis Majoris

    Science.gov (United States)

    Richards, A. M. S.; Impellizzeri, C. M. V.; Humphreys, E. M.; Vlahakis, C.; Vlemmings, W.; Baudry, A.; De Beck, E.; Decin, L.; Etoka, S.; Gray, M. D.; Harper, G. M.; Hunter, T. R.; Kervella, P.; Kerschbaum, F.; McDonald, I.; Melnick, G.; Muller, S.; Neufeld, D.; O'Gorman, E.; Parfenov, S. Yu.; Peck, A. B.; Shinnaga, H.; Sobolev, A. M.; Testi, L.; Uscanga, L.; Wootten, A.; Yates, J. A.; Zijlstra, A.

    2014-12-01

    Aims: Cool, evolved stars have copious, enriched winds. Observations have so far not fully constrained models for the shaping and acceleration of these winds. We need to understand the dynamics better, from the pulsating stellar surface to ~10 stellar radii, where radiation pressure on dust is fully effective. Asymmetric nebulae around some red supergiants imply the action of additional forces. Methods: We retrieved ALMA Science Verification data providing images of sub-mm line and continuum emission from VY CMa. This enables us to locate water masers with milli-arcsec accuracy and to resolve the dusty continuum. Results: The 658, 321, and 325 GHz masers lie in irregular, thick shells at increasing distances from the centre of expansion. For the first time this is confirmed as the stellar position, coinciding with a compact peak offset to the NW of the brightest continuum emission. The maser shells overlap but avoid each other on scales of up to 10 au. Their distribution is broadly consistent with excitation models but the conditions and kinematics are complicated by wind collisions, clumping, and asymmetries. Appendices are available in electronic form at http://www.aanda.org

  13. Very long baseline interferometric observations of the hydroxyl masers in VY Canis Majoris

    Science.gov (United States)

    Reid, M. J.; Muhleman, D. O.

    1978-01-01

    Results are presented for spectral-line VLBI observations of the OH emission from VY CMa. The main-line (1665 and 1667 MHz) emission was mapped with an angular resolution of 0.02 arcsec by analyzing interferometer phase data. The main-line emission comes from many maser components of apparent size less than 0.03 arcsec which are separated by up to 0.5 arcsec. New maser features near the center of the OH spectra were detected and found to lie within the region encompassed by the low-velocity OH emission. The 1612-MHz emission was mapped by Fourier inversion of the VLBI data from two baselines. All spatially isolated maser components appeared smaller than 0.15 arcsec; however, the maser emission is very complex at most velocities. Maser components within a velocity range of 1.3 km/s are often separated by more than 1 arcsec, while components more than 10 km/s apart in each emission complex are often coincident to 0.2 arcsec.

  14. Pure rotational spectra of TiO and TiO2 in VY Canis Majoris

    Science.gov (United States)

    Kamiński, T.; Gottlieb, C. A.; Menten, K. M.; Patel, N. A.; Young, K. H.; Brünken, S.; Müller, H. S. P.; McCarthy, M. C.; Winters, J. M.; Decin, L.

    2013-03-01

    We report the first detection of pure rotational transitions of TiO and TiO2 at (sub-)millimeter wavelengths towards the red supergiant VY CMa. A rotational temperature, Trot, of about 250 K was derived for TiO2. Although Trot was not well constrained for TiO, it is likely somewhat higher than that of TiO2. The detection of the Ti oxides confirms that they are formed in the circumstellar envelopes of cool oxygen-rich stars and may be the "seeds" of inorganic-dust formation, but alternative explanations for our observation of TiO and TiO2 in the cooler regions of the envelope cannot be ruled out at this time. The observations suggest that a significant fraction of the oxides is not converted to dust, but instead remains in the gas phase throughout the outflow. Based on observations carried out with the Submillimeter Array and IRAM Plateau de Bure Interferometer.Plateau de Bure data (FITS file) is only available at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/551/A113

  15. The Three-Dimensional Morphology of VY Canis Majoris. I. The Kinematics of the Ejecta

    Science.gov (United States)

    Humphreys, Roberta M.; Helton, L. Andrew; Jones, Terry J.

    2007-06-01

    Images of the complex circumstellar nebula associated with the famous red supergiant VY CMa show evidence for multiple and asymmetric mass-loss events over the past 1000 yr. Doppler velocities of the arcs and knots in the ejecta show that they are not only spatially distinct but also kinematically separate from the surrounding diffuse material. In this paper we describe second-epoch HST WFPC2 images to measure the transverse motions, which when combined with the radial motions provide a complete picture of the kinematics of the ejecta, including the total space motions and directions of the outflows. Our results show that the arcs and clumps of knots are moving at different velocities, in different directions, and at different angles relative to the plane of the sky and to the star, confirming their origin from eruptions at different times and from physically separate regions on the star. We conclude that the morphology and kinematics of the arcs and knots are consistent with a history of mass ejections not aligned with any presumed axis of symmetry. The arcs and clumps represent relatively massive outflows and ejections of gas very likely associated with large-scale convective activity and magnetic fields. Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  16. The Three-Dimensional Morphology of VY Canis Majoris. II. Polarimetry and the Line-of-Sight Distribution of the Ejecta

    Science.gov (United States)

    Jones, Terry Jay; Humphreys, Roberta M.; Helton, L. Andrew; Gui, Changfeng; Huang, Xiang

    2007-06-01

    We use imaging polarimetry taken with the HST Advanced Camera for Surveys High Resolution Camera to explore the three-dimensional structure of the circumstellar dust distribution around the red supergiant VY Canis Majoris. The polarization vectors of the nebulosity surrounding VY CMa show a strong centrosymmetric pattern in all directions except directly east and range from 10% to 80% in fractional polarization. In regions that are optically thin, and therefore likely to have only single scattering, we use the fractional polarization and photometric color to locate the physical position of the dust along the line of sight. Most of the individual arclike features and clumps seen in the intensity image are also features in the fractional polarization map. These features must be distinct geometric objects. If they were just local density enhancements, the fractional polarization would not change so abruptly at the edge of the feature. The location of these features in the ejecta of VY CMa using polarimetry provides a determination of their three-dimensional geometry independent of, but in close agreement with, the results from our study of their kinematics (Paper I). Based on observations with the NASA/ESA Hubble Space Telescope, obtained at the Space Telescope Science Institute, which is operated by the Association of Universities for Research in Astronomy, Inc., under NASA contract NAS 5-26555.

  17. Infrared Space Observatory Observations of Far-Infrared Rotational Emission Lines of Water Vapor toward the Supergiant Star VY Canis Majoris

    Science.gov (United States)

    Neufeld, David A.; Feuchtgruber, Helmut; Harwit, Martin; Melnick, Gary J.

    1999-06-01

    We report the detection of numerous far-infrared emission lines of water vapor toward the supergiant star VY Canis Majoris. A 29.5-45 μm grating scan of VY CMa, obtained using the Short-Wavelength Spectrometer (SWS) of the Infrared Space Observatory at a spectral resolving power λ/Δλ of ~2000, reveals at least 41 spectral features due to water vapor that together radiate a total luminosity of ~25 Lsolar. In addition to pure rotational transitions within the ground vibrational state, these features include rotational transitions within the (010) excited vibrational state. The spectrum also shows the 2Π1/2(J=5/2)VY CMa were carried out in the instrument's Fabry-Perot mode for three water transitions: the 725-616 line at 29.8367 μm, the 441-312 line at 31.7721 μm, and the 432-303 line at 40.6909 μm. The higher spectral resolving power λ/Δλ of approximately 30,000 thereby obtained permits the line profiles to be resolved spectrally for the first time and reveals the ``P Cygni'' profiles that are characteristic of emission from an outflowing envelope. Based on observations with ISO, an ESA project with instruments funded by ESA Member States (especially the PI countries: France, Germany, the Netherlands, and the UK) with the participation of ISAS and NASA.

  18. Oxygen-rich Mass Loss with a Pinch of Salt: NaCl in the Circumstellar Gas of IK Tauri and VY Canis Majoris

    Science.gov (United States)

    Milam, S. N.; Apponi, A. J.; Woolf, N. J.; Ziurys, L. M.

    2007-10-01

    The NaCl molecule has been observed in the circumstellar envelopes of VY Canis Majoris (VY CMa) and IK Tauri (IK Tau)-the first identifications of a metal refractory in oxygen-rich shells of evolved stars. Five rotational transitions of NaCl at 1 and 2 mm were detected toward VY CMa and three 1 mm lines were observed toward IK Tau, using the telescopes of the Arizona Radio Observatory. In both objects, the line widths of the NaCl profiles were extremely narrow relative to those of other molecules, indicating that sodium chloride has not reached the terminal outflow velocity in either star, likely a result of early condensation onto grains. Modeling the observed spectra suggests abundances, relative to H2, of f~5×10-9 in VY CMa and f~4×10-9 in IK Tau, with source sizes of 0.5" and 0.3", respectively. The extent of these sources is consistent with the size of the dust acceleration zones in both stars. NaCl therefore appears to be at least as abundant in O-rich shells as compared to C-rich envelopes, where f~(0.2-2)×10-9, although it appears to condense out earlier in the O-rich case. Chemical equilibrium calculations indicate that NaCl is the major carrier of sodium at T~1100 K for oxygen-rich stars, with predicted fractional abundances in good agreement with the observations. These measurements suggest that crystalline salt may be an important condensate for sodium in both C- and O-rich circumstellar shells.

  19. Interferometric Observation of the Highly Polarized SiO Maser Emission from the v = 1, J = 5-4 Transition Associated with VY Canis Majoris

    Science.gov (United States)

    Shinnaga, Hiroko; Moran, James M.; Young, Ken H.; Ho, Paul T. P.

    2004-11-01

    We used the Submillimeter Array to image the SiO maser emission in the v=1, J=5-4 transition associated with the peculiar red supergiant VY Canis Majoris. We identified seven maser components and measured their relative positions and linear polarization properties. Five of the maser components are coincident to within about 150 mas (~200 AU at the distance of 1.5 kpc); most of them may originate in the circumstellar envelope at a radius of about 50 mas from the star along with the SiO masers in the lowest rotational transitions. Our measurements show that two of the maser components may be offset from the inner stellar envelope (at the 3 σ level of significance) and may be part of a larger bipolar outflow associated with VY CMa identified by Shinnaga et al. The strongest maser feature at a velocity of 35.9 km s-1 has a 60% linear polarization, and its polarization direction is aligned with the bipolar axis. Such a high degree of polarization suggests that maser inversion is due to radiative pumping. Five of the other maser features have significant linear polarization.

  20. Radio Interferometric Detection of TiO and TiO_2 in VY Canis Majoris: "seeds" of Inorganic Dust Formation

    Science.gov (United States)

    Brunken, S.; Muller, H. S. P.; Kaminski, T.; Menten, K. M.; Gott-Lieb, C. A.; Patel, N. A.; Young, K. H.; McCarthy, M. C.; Winters, J. M.; Decin, L.

    2013-06-01

    Circumstellar envelopes around late-type stars harbour a rich variety of molecular gas and copious amounts of dust, originating from the mass-loss of the central star during the asymptotic giant branch (AGB) or the red supergiant phase. The formation of dust in these objects, in particular the first nucleation stages out of gas phase molecules, is still poorly understood. Here we report the first detection of pure rotational transitions of the two simplest titanium oxides, TiO and TiO_2, towards the oxygen-rich red supergiant VY Canis Majoris (VY CMa). This actually represents the first secure identification of TiO_2 in space. Observations of several rotational emission lines of both species with the Submillimeter Array (SMA) in the 345 GHz-band and with the IRAM Plateau de Bure Interferometer (PdBI) around 220 GHz confirm the presence of these refractory species in the cool (<1000 K) circumstellar envelope in a region several times the size of the dust formation zone. The role of Ti oxides as "seeds" of inorganic dust formation in oxygen-rich circumstellar envelopes will be discussed in view of the present observations.

  1. AN INTERFEROMETRIC SPECTRAL LINE AND IMAGING SURVEY OF VY CANIS MAJORIS IN THE 345 GHz BAND

    International Nuclear Information System (INIS)

    Kamiński, T.; Menten, K. M.; Gottlieb, C. A.; Young, K. H.; Patel, N. A.

    2013-01-01

    A spectral line survey of the oxygen-rich red supergiant VY Canis Majoris was made between 279 and 355 GHz with the Submillimeter Array (SMA). Two hundred twenty-three spectral features from 19 molecules (not counting isotopic species of some of them) were observed, including the rotational spectra of TiO, TiO 2 , and AlCl for the first time in this source. The parameters and an atlas of all spectral features are presented. Observations of each line with a synthesized beam of ∼0.''9, reveal the complex kinematics and morphology of the nebula surrounding VY CMa. Many of the molecules are observed in high-lying rotational levels or in excited vibrational levels. From these, it was established that the main source of the submillimeter-wave continuum (dust) and the high-excitation molecular gas (the star) are separated by about 0.''15. Apparent coincidences between the molecular gas observed with the SMA, and some of the arcs and knots observed at infrared wavelengths and in the optical scattered light by the Hubble Space Telescope are identified. The observations presented here provide important constraints on the molecular chemistry in oxygen-dominated circumstellar environments and a deeper picture of the complex circumstellar environment of VY CMa

  2. Probing Hypergiant Mass Loss with Adaptive Optics Imaging and Polarimetry in the Infrared: MMT-Pol and LMIRCam Observations of IRC +10420 and VY Canis Majoris

    Science.gov (United States)

    Shenoy, Dinesh P.; Jones, Terry J.; Packham, Chris; Lopez-Rodriguez, Enrique

    2015-07-01

    We present 2-5 μm adaptive optics (AO) imaging and polarimetry of the famous hypergiant stars IRC +10420 and VY Canis Majoris. The imaging polarimetry of IRC +10420 with MMT-Pol at 2.2 μ {m} resolves nebular emission with intrinsic polarization of 30%, with a high surface brightness indicating optically thick scattering. The relatively uniform distribution of this polarized emission both radially and azimuthally around the star confirms previous studies that place the scattering dust largely in the plane of the sky. Using constraints on scattered light consistent with the polarimetry at 2.2 μ {m}, extrapolation to wavelengths in the 3-5 μm band predicts a scattered light component significantly below the nebular flux that is observed in our Large Binocular Telescope/LMIRCam 3-5 μm AO imaging. Under the assumption this excess emission is thermal, we find a color temperature of ˜500 K is required, well in excess of the emissivity-modified equilibrium temperature for typical astrophysical dust. The nebular features of VY CMa are found to be highly polarized (up to 60%) at 1.3 μm, again with optically thick scattering required to reproduce the observed surface brightness. This star’s peculiar nebular feature dubbed the “Southwest Clump” is clearly detected in the 3.1 μm polarimetry as well, which, unlike IRC +10420, is consistent with scattered light alone. The high intrinsic polarizations of both hypergiants’ nebulae are compatible with optically thick scattering for typical dust around evolved dusty stars, where the depolarizing effect of multiple scatters is mitigated by the grains’ low albedos. Observations reported here were obtained at the MMT Observatory, a joint facility of the Smithsonian Institution and the University of Arizona.

  3. ALMA observations of anisotropic dust mass loss in the inner circumstellar environment of the red supergiant VY Canis Majoris

    NARCIS (Netherlands)

    O'Gorman, E.; Vlemmings, W.; Richards, A.M.S.; Baudry, A.; De Beck, E.; Decin, L.; Harper, G.M.; Humphreys, E.M.; Kervella, P.; Khouri, T.; Muller, S.

    2015-01-01

    The processes leading to dust formation and the subsequent role it plays in driving mass loss in cool evolved stars is an area of intense study. Here we present high resolution ALMA Science Verification data of the continuum emission around the highly evolved oxygen-rich red supergiant VY CMa. These

  4. Fundamental properties and atmospheric structure of the red supergiant VY Canis Majoris based on VLTI/AMBER spectro-interferometry

    Science.gov (United States)

    Wittkowski, M.; Hauschildt, P. H.; Arroyo-Torres, B.; Marcaide, J. M.

    2012-04-01

    Aims: We investigate the atmospheric structure and fundamental properties of the red supergiant VY CMa. Methods: We obtained near-infrared spectro-interferometric observations of VY CMa with spectral resolutions of 35 and 1500 using the AMBER instrument at the VLTI. Results: The visibility data indicate the presence of molecular layers of water vapor and CO in the extended atmosphere with an asymmetric morphology. The uniform disk diameter in the water band around 2.0 μm is increased by ~20% compared to the near-continuum bandpass at 2.20-2.25 μm, and in the CO band at 2.3-2.5 μm it is increased by up to ~50%. The closure phases indicate relatively small deviations from point symmetry close to the photospheric layer, and stronger deviations in the extended H2O and CO layers. Making use of the high spatial and spectral resolution, a near-continuum bandpass can be isolated from contamination by molecular and dusty layers, and the Rosseland-mean photospheric angular diameter is estimated to 11.3 ± 0.3 mas based on a PHOENIX atmosphere model. Together with recent high-precision estimates of the distance and spectro-photometry, this estimate corresponds to a radius of 1420 ± 120 R⊙ and an effective temperature of 3490 ± 90 K. Conclusions: VY CMa exhibits asymmetric, possibly clumpy, atmospheric layers of H2O and CO, which are not co-spatial, within a larger elongated dusty envelope. Our revised fundamental parameters put VY CMa close to the Hayashi limit of recent evolutionary tracks of initial mass 25 M⊙ with rotation or 32 M⊙ without rotation, shortly before evolving blueward in the HR-diagram. Based on observations made with the VLT Interferometer (VLTI) at Paranal Observatory under programme ID 386.D-0012.Figures 2, 3 and 5 are available in electronic form at http://www.aanda.org

  5. High-Resolution, Long-Slit Spectroscopy of VY Canis Majoris: The Evidence for Localized High Mass Loss Events

    Science.gov (United States)

    Humphreys, Roberta M.; Davidson, Kris; Ruch, Gerald; Wallerstein, George

    2005-01-01

    High spatial and spectral resolution spectroscopy of the OH/IR supergiant VY CMa and its circumstellar ejecta reveals evidence for high mass loss events from localized regions on the star occurring over the past 1000 yr. The reflected absorption lines and the extremely strong K I emission lines show a complex pattern of velocities in the ejecta. We show that the large, dusty northwest arc, expanding at ~50 km s-1 with respect to the embedded star, is kinematically distinct from the surrounding nebulosity and was ejected about 400 yr ago. Other large, more filamentary loops were probably expelled as much as 800-1000 yr ago, whereas knots and small arcs close to the star resulted from more recent events 100-200 yr ago. The more diffuse, uniformly distributed gas and dust is surprisingly stationary, with little or no velocity relative to the star. This is not what we would expect for the circumstellar material from an evolved red supergiant with a long history of mass loss. We therefore suggest that the high mass loss rate for VY CMa is a measure of the mass carried out by these specific ejections accompanied by streams or flows of gas through low-density regions in the dust envelope. VY CMa may thus be our most extreme example of stellar activity, but our results also bring into question the evolutionary state of this famous star. In a separate appendix, we discuss the origin of the very strong K I and other rare emission lines in its spectrum.

  6. ALMA observations of anisotropic dust mass loss in the inner circumstellar environment of the red supergiant VY Canis Majoris

    Science.gov (United States)

    O'Gorman, E.; Vlemmings, W.; Richards, A. M. S.; Baudry, A.; De Beck, E.; Decin, L.; Harper, G. M.; Humphreys, E. M.; Kervella, P.; Khouri, T.; Muller, S.

    2015-01-01

    The processes leading to dust formation and the subsequent role it plays in driving mass loss in cool evolved stars is an area of intense study. Here we present high resolution ALMA Science Verification data of the continuum emission around the highly evolved oxygen-rich red supergiant VY CMa. These data enable us to study the dust in its inner circumstellar environment at a spatial resolution of 129 mas at 321 GHz and 59 mas at 658 GHz, thus allowing us to trace dust on spatial scales down to 11 R⋆ (71 AU). Two prominent dust components are detected and resolved. The brightest dust component, C, is located 334 mas (61 R⋆) southeast of the star and has a dust mass of at least 2.5 × 10-4 M⊙. It has a dust emissivity spectral index of β = -0.1 at its peak, implying that it is optically thick at these frequencies with a cool core of Td ≲ 100 K. Interestingly, not a single molecule in the ALMA data has emission close to the peak of this massive dust clump. The other main dust component, VY, is located at the position of the star and contains a total dust mass of 4.0 × 10-5 M⊙. It also contains a weaker dust feature extending over 60 R⋆ to the north with the total component having a typical dust emissivity spectral index of β = 0.7. We find that at least 17% of the dust mass around VY CMa is located in clumps ejected within a more quiescent roughly spherical stellar wind, with a quiescent dust mass loss rate of 5 × 10-6 M⊙yr-1. The anisotropic morphology of the dust indicates a continuous, directed mass loss over a few decades, suggesting that this mass loss cannot be driven by large convection cells alone. Appendices are available in electronic form at http://www.aanda.org

  7. Evidence for Stable v = 0, j = 1 → 0 SiO Maser Emission from VY Canis Majoris

    Science.gov (United States)

    McIntosh, G. C.; Rislow, B.

    2009-02-01

    Observations of the SiO v = 0, J = 1 → 0 spectra from VY CMa from 2003 through 2006 indicate an unusually long-lived, highly linearly polarized maser emission at a V lsr of approximately 18.5 km s-1. A time series cross-correlation analysis has been developed for calculating the characteristic lifetime of linearly polarized spectra. Applying the cross-correlation to these spectra indicates a characteristic lifetime of 5600 ± 400 days. These emission characteristics may be generated in a region of relatively stable outflow geometry and magnetic field rather than in the more ephemeral circumstellar environment.

  8. EVIDENCE FOR STABLE v = 0, J = 1 → 0 SiO MASER EMISSION FROM VY CANIS MAJORIS

    International Nuclear Information System (INIS)

    McIntosh, G. C.; Rislow, B.

    2009-01-01

    Observations of the SiO v = 0, J = 1 → 0 spectra from VY CMa from 2003 through 2006 indicate an unusually long-lived, highly linearly polarized maser emission at a V lsr of approximately 18.5 km s -1 . A time series cross-correlation analysis has been developed for calculating the characteristic lifetime of linearly polarized spectra. Applying the cross-correlation to these spectra indicates a characteristic lifetime of 5600 ± 400 days. These emission characteristics may be generated in a region of relatively stable outflow geometry and magnetic field rather than in the more ephemeral circumstellar environment.

  9. Mid-Infrared Interferometry on Spectral Lines. II. Continuum (Dust) Emission Around IRC +10216 and VY Canis Majoris

    Science.gov (United States)

    Monnier, J. D.; Danchi, W. C.; Hale, D. S.; Lipman, E. A.; Tuthill, P. G.; Townes, C. H.

    2000-11-01

    The University of California Berkeley Infrared Spatial Interferometer has measured the mid-infrared visibilities of the carbon star IRC +10216 and the red supergiant VY CMa. The dust shells around these sources have been previously shown to be time variable, and these new data are used to probe the evolution of the dust shells on a decade timescale, complementing contemporaneous studies at other wavelengths. Self-consistent, spherically symmetric models at maximum and minimum light both show the inner radius of the IRC +10216 dust shell to be much larger (150 mas) than expected from the dust-condensation temperature, implying that dust production has slowed or stopped in recent years. Apparently, dust does not form every pulsational cycle (638 days), and these mid-infrared results are consistent with recent near-infrared imaging, which indicates little or no new dust production in the last 3 yr. Spherically symmetric models failed to fit recent VY CMa data, implying that emission from the inner dust shell is highly asymmetric and/or time variable.

  10. Mid-Infrared Interferometry on Spectral Lines. III. Ammonia and Silane around IRC +10216 and VY Canis Majoris

    Science.gov (United States)

    Monnier, J. D.; Danchi, W. C.; Hale, D. S.; Tuthill, P. G.; Townes, C. H.

    2000-11-01

    Using the University of California Berkeley Infrared Spatial Interferometer with a radio frequency (RF) filter bank, the first interferometric observations of mid-infrared molecular absorption features of ammonia (NH3) and silane (SiH4) with very high spectral resolution (λ/Δλ~105) were made. Under the assumptions of spherical symmetry and uniform outflow, these new data permitted the molecular stratification around carbon star IRC +10216 and red supergiant VY CMa to be investigated. For IRC +10216, both ammonia and silane were found to form in the dusty outflow significantly beyond both the dust formation and gas acceleration zones. Specifically, ammonia was found to form before silane in a region of decaying gas turbulence (>~20R*), while the silane is produced in a region of relatively smooth gas flow much farther from the star (>~80R*). The depletion of gas-phase SiS onto grains soon after dust formation may fuel silane-producing reactions on the grain surfaces. For VY CMa, a combination of interferometric and spectral observations suggest that NH3 is forming near the termination of the gas acceleration phase in a region of high gas turbulence (~40R*).

  11. The ISO Long Wavelength Spectrometer line spectrum of VY Canis Majoris and other oxygen-rich evolved stars

    Science.gov (United States)

    Polehampton, E. T.; Menten, K. M.; van der Tak, F. F. S.; White, G. J.

    2010-02-01

    Context. The far-infrared spectra of circumstellar envelopes around various oxygen-rich stars were observed using the ISO Long Wavelength Spectrometer (LWS). These have been shown to be spectrally rich, particularly in water lines, indicating a high H2O abundance. Aims: We have examined high signal-to-noise ISO LWS observations of the luminous supergiant star, VY CMa, with the aim of identifying all of the spectral lines. By paying particular attention to water lines, we aim to separate the lines due to other species, in particular, to prepare for forthcoming observations that will cover the same spectral range using Herschel PACS and at higher spectral resolution using Herschel HIFI and SOFIA. Methods: We have developed a fitting method to account for blended water lines using a simple weighting scheme to distribute the flux. We have used this fit to separate lines due to other species which cannot be assigned to water. We have applied this approach to several other stars which we compare with VY CMa. Results: We present line fluxes for the unblended H2O and CO lines, and present detections of several possible ν2=1 vibrationally excited water lines. We also identify blended lines of OH, one unblended and several blended lines of NH3, and one possible detection of H3O+. Conclusions: The spectrum of VY CMa shows a detection of emission from virtually every water line up to 2000 K above the ground state, as well as many additional higher energy and some vibrationally excited lines. A simple rotation diagram analysis shows large scatter (probably due to some optically thick lines). The fit gives a rotational temperature of 670+210-130 K, and lower limit on the water column density of (7.0±1.2) × 1019 cm-2. We estimate a CO column density ~100 times lower, showing that water is the dominant oxygen carrier. The other stars that we examined have similar rotation temperatures, but their H2O column densities are an order of magnitude lower (as are the mass loss rates

  12. Polarisation observations of VY Canis Majoris H2O 532-441 620.701 GHz maser emission with HIFI

    Science.gov (United States)

    Harwit, M.; Houde, M.; Sonnentrucker, P.; Boogert, A. C. A.; Cernicharo, J.; De Beck, E.; Decin, L.; Henkel, C.; Higgins, R. D.; Jellema, W.; Kraus, A.; McCoey, C.; Melnick, G. J.; Menten, K. M.; Risacher, C.; Teyssier, D.; Vaillancourt, J. E.; Alcolea, J.; Bujarrabal, V.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Olofsson, H.; Planesas, P.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.

    2010-10-01

    Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims: We have aimed to elucidate the nature and structure of the VY CMa water vapour masers in part by observationally testing a theoretical prediction of the relative strengths of the 620.701 GHz and the 22.235 GHz maser components of ortho H2O. Methods: In its high-resolution mode (HRS) the Herschel Heterodyne Instrument for the Far Infrared (HIFI) offers a frequency resolution of 0.125 MHz, corresponding to a line-of-sight velocity of 0.06 km s-1, which we employed to obtain the strength and linear polarisation of maser spikes in the spectrum of VY CMa at 620.701 GHz. Simultaneous ground based observations of the 22.235 GHz maser with the Max-Planck-Institut für Radioastronomie 100-m telescope at Effelsberg, provided a ratio of 620.701 GHz to 22.235 GHz emission. Results: We report the first astronomical detection to date of H2O maser emission at 620.701 GHz. In VY CMa both the 620.701 and the 22.235 GHz polarisation are weak. At 620.701 GHz the maser peaks are superposed on what appears to be a broad emission component, jointly ejected from the star. We observed the 620.701 GHz emission at two epochs 21 days apart, both to measure the potential direction of linearly polarised maser components and to obtain a measure of the longevity of these components. Although we do not detect significant polarisation levels in the core of the line, they rise up to approximately 6% in its wings. Herschel is an ESA space observatory with science instruments provided by European-led Principal Investigator consortia and with important participation from NASA.Appendix (page 5) is only available in electronic form at http://www.aanda.org

  13. Characteristic Lifetime Of A Polarized Feature In The V=0, J=1-0 Sio Maser VY Canis Majoris

    Science.gov (United States)

    Rislow, Benjamin; McIntosh, G. C.

    2008-05-01

    A time series cross correlation analysis has been developed for calculating the characteristic lifetime of linearly polarized features in the spectrum of silicon monoxide masers. Our observations of VY CMa in the v=0, J=1→0; transition from June 2003 to March 2006 revealed a highly linearly polarized feature at Vlsr=18.5 km s-1. Applying the cross correlation to this feature gave a characteristic lifetime of 2800 days. This time is much longer than the v=1, J=2→1; transition's lifetime of 645 days and indicates that the two transitions occur under different physical conditions. This research was supported by the University of Minnesota and the University of Minnesota, Morris.

  14. Magnetically aligned dust and SiO maser polarisation in the envelope of the red supergiant VY Canis Majoris

    Science.gov (United States)

    Vlemmings, W. H. T.; Khouri, T.; Martí-Vidal, I.; Tafoya, D.; Baudry, A.; Etoka, S.; Humphreys, E. M. L.; Jones, T. J.; Kemball, A.; O'Gorman, E.; Pérez-Sánchez, A. F.; Richards, A. M. S.

    2017-07-01

    Aims: Polarisation observations of circumstellar dust and molecular (thermal and maser) lines provide unique information about dust properties and magnetic fields in circumstellar envelopes of evolved stars. Methods: We use Atacama Large Millimeter/submillimeter Array (ALMA) Band 5 science verification observations of the red supergiant VY CMa to study the polarisation of SiO thermal/maser lines and dust continuum at 1.7 mm wavelength. We analyse both linear and circular polarisation and derive the magnetic field strength and structure, assuming the polarisation of the lines originates from the Zeeman effect, and that of the dust originates from aligned dust grains. We also discuss other effects that could give rise to the observed polarisation. Results: We detect, for the first time, significant polarisation ( 3%) of the circumstellar dust emission at millimeter wavelengths. The polarisation is uniform with an electric vector position angle of 8°. Varying levels of linear polarisation are detected for the J = 4 - 328SiO v = 0, 1, 2, and 29SiO v = 0, 1 lines, with the strongest polarisation fraction of 30% found for the 29SiO v = 1 maser. The linear polarisation vectors rotate with velocity, consistent with earlier observations. We also find significant (up to 1%) circular polarisation in several lines, consistent with previous measurements. We conclude that the detection is robust against calibration and regular instrumental errors, although we cannot yet fully rule out non-standard instrumental effects. Conclusions: Emission from magnetically aligned grains is the most likely origin of the observed continuum polarisation. This implies that the dust is embedded in a magnetic field >13 mG. The maser line polarisation traces the magnetic field structure. The magnetic field in the gas and dust is consistent with an approximately toroidal field configuration, but only higher angular resolution observations will be able to reveal more detailed field structure. If the

  15. ALMA-resolved salt emission traces the chemical footprint and inner wind morphology of VY Canis Majoris

    Science.gov (United States)

    Decin, L.; Richards, A. M. S.; Millar, T. J.; Baudry, A.; De Beck, E.; Homan, W.; Smith, N.; Van de Sande, M.; Walsh, C.

    2016-07-01

    Context. At the end of their lives, most stars lose a significant amount of mass through a stellar wind. The specific physical and chemical circumstances that lead to the onset of the stellar wind for cool luminous stars are not yet understood. Complex geometrical morphologies in the circumstellar envelopes prove that various dynamical and chemical processes are interlocked and that their relative contributions are not easy to disentangle. Aims: We aim to study the inner-wind structure (RVY CMa, the archetype for the class of luminous red supergiant stars experiencing high mass loss. Specifically, the objective is to unravel the density structure in the inner envelope and to examine the chemical interaction between gas and dust species. Methods: We analyse high spatial resolution (~0.̋24×0.̋13) ALMA science verification (SV) data in band 7, in which four thermal emission lines of gaseous sodium chloride (NaCl) are present at high signal-to-noise ratio. Results: For the first time, the NaCl emission in the inner wind region of VY CMa is spatially resolved. The ALMA observations reveal the contribution of up to four different spatial regions. The NaCl emission pattern is different compared to the dust continuum and TiO2 emission already analysed from the ALMA SV data. The emission can be reconciled with an axisymmetric geometry, where the lower density polar/rotation axis has a position angle of ~50° measured from north to east. However, this picture cannot capture the full morphological diversity, and discrete mass ejection events need to be invoked to explain localized higher-density regions. The velocity traced by the gaseous NaCl line profiles is significantly lower than the average wind terminal velocity, and much slower than some of the fastest mass ejections, signalling a wide range of characteristic speeds for the mass loss. Gaseous NaCl is detected far beyond the main dust condensation region. Realising the refractory nature of this metal halide, this

  16. Spatial heterodyne interferometry of VY Canis Major's, alpha Orionis, alpha Scorpii, and R leonis at 11 microns

    Science.gov (United States)

    Sutton, E. C.; Storey, J. W. V.; Betz, A. L.; Townes, C. H.; Spears, D. L.

    1977-01-01

    Using the technique of heterodyne interferometry, measurements were made of the spatial distribution of 11 micron radiation from four late type stars. The circumstellar shells surrounding VY Canis Majoris, alpha Orionis, and alpha Scorpii were resolved, whereas that of R Leonis was only partially resolved at a fringe spacing of 0.4 sec.

  17. First mm-VLBI Observations between the TRAO 14-m and the NRO 45-m Telescopes: Observations of 86 GHz SiO Masers in VY Canis Majoris

    Science.gov (United States)

    Shibata, Katsunori M.; Chung, Hyung-Soo; Kameno, Seiji; Roh, Duk-Gyoo; Umemoto, Tomofumi; Kim, Kwang-Dong; Asada, Keiichi; Han, Seog-Tae; Mochizuki, Nanako; Cho, Se-Hyung; Sawada-Satoh, Satoko; Kim, Hyun-Goo; Bushimata, Takeshi; Minh, Young Chol; Miyaji, Takeshi; Kuno, Nario; Mikoshiba, Hiroshi; Sunada, Kazuyoshi; Inoue, Makoto; Kobayashi, Hideyuki

    2004-06-01

    We have made VLBI observations at 86GHz using a 1000-km baseline between Korea and Japan with successful detections of SiO v = 1, J = 2 - 1 maser emissions from VY CMa and Orion KL in 2001 June. This was the first VLBI result for this baseline and the first astronomical VLBI observation for the Korean telescope. Since then, we observed SiO v = 1, J = 2 - 1 maser emission in VY CMa in 2002 January and 2003 February and derived the distributions of the maser emissions. Our results show that the maser emissions extend over 2-4 stellar radii, and were within the inner radius of the dust shell. We observed other SiO maser sources and continuum sources, and 86-GHz continuum emissions were detected from three continuum sources. It was verified that this baseline has a performance comparable to the most sensitive baseline in the VLBA and the CMVA, and is capable of investigating the proper motions of maser features in circumstellar envelopes using monitoring observations.

  18. HIFISTARS Herschel/HIFI observations of VY Canis Majoris. Molecular-line inventory of the envelope around the largest known star

    Science.gov (United States)

    Alcolea, J.; Bujarrabal, V.; Planesas, P.; Teyssier, D.; Cernicharo, J.; De Beck, E.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Melnick, G.; Menten, K. M.; Neufeld, D. A.; Olofsson, H.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.

    2013-11-01

    Aims: The study of the molecular gas in the circumstellar envelopes of evolved stars is normally undertaken by observing lines of CO (and other species) in the millimetre-wave domain. In general, the excitation requirements of the observed lines are low at these wavelengths, and therefore these observations predominantly probe the cold outer envelope while studying the warm inner regions of the envelopes normally requires sub-millimetre (sub-mm) and far-infrared (FIR) observational data. Methods: To gain insight into the physical conditions and kinematics of the warm (100-1000 K) gas around the red hyper-giant VY CMa, we performed sensitive high spectral resolution observations of molecular lines in the sub-mm/FIR using the HIFI instrument of the Herschel Space Observatory. We observed CO, H2O, and other molecular species, sampling excitation energies from a few tens to a few thousand K. These observations are part of the Herschel guaranteed time key program HIFISTARS. Results: We detected the J = 6-5, J = 10-9, and J = 16-15 lines of 12CO and 13CO at ~100, 300, and 750 K above the ground state (and the 13CO J = 9-8 line). These lines are crucial for improving the modelling of the internal layers of the envelope around VY CMa. We also detected 27 lines of H2O and its isotopomers, and 96 lines of species such as NH3, SiO, SO, SO2 HCN, OH and others, some of them originating from vibrationally excited levels. Three lines were not unambiguously assigned. Conclusions: Our observations confirm that VY CMa's envelope must consist of two or more detached components. The molecular excitation in the outer layers is significantly lower than in the inner ones, resulting in strong self-absorbed profiles in molecular lines that are optically thick in this outer envelope, for instance, low-lying lines of H2O. Except for the most abundant species, CO and H2O, most of the molecular emission detected at these sub-mm/FIR wavelengths arise from the central parts of the envelope. The

  19. The evolutionary state of the Beta Canis Majoris variables

    International Nuclear Information System (INIS)

    Shobbrook, R.R.

    1978-01-01

    New β photometry is presented for all the known β Canis Majoris variables and for other bright early B stars observable from the southern hemisphere which were close to the β CMa stars in a β/[c 1 ] diagram published earlier. The new β values are accurate to +- 0.002 or 0.003 mag and enable the 'instability strip' along which the variables lie to be defined much more precisely. Several of the other B stars also lie in the strip; most of these have already been found to be non-variable in a subsidiary observing programme. (author)

  20. Kinematics of the CSE in VY CMa

    Science.gov (United States)

    Choi, Yoon Kyung

    2009-07-01

    We report on astrometric results of H2O and SiO masers in the circumstellar envelopes of VY Canis Majoris (VY CMa) carried out with VERA for 2 years. Absolute positions and proper motions of 3 different frequencies of masers were measured with phase-referencing analyses. Using the positions and the 3-dimensional velocities of the masers, we considered the 3-dimensional structures and kinematics of the circumstellar envelopes around VY CMa. The H2O masers show bipolar outflow along the line of sight, and the SiO masers have both expanding and contracting motions with less than 5 km/s.

  1. Maser observation in VY CMa with VERA

    Science.gov (United States)

    Choi, Yoon Kyung

    We present the results of multi-epoch VERA (VLBI Exploration of Radio Astrometry) observations of H2O masers at 22 GHz and ^28SiO masers at 43 GHz in the supergiant VY Canis Majoris (hereafter, VY CMa). We estimate the inner motion of H2O masers over 6 months and that of SiO masers over 1 month. Using the inner motion, we calculated the statistical parallax of VY CMa. The size of the emitting region for ^28SiO masers is R_SiO ~1.81-2.89 R_* and it is consistent with the previous study.

  2. The Circumstellar Environment of VY CMa

    Science.gov (United States)

    Smith, N.; Humphreys, R. M.; Krautter, J.; Gehrz, R. D.; Davidson, K.; Jones, T. J.; Hubrig, S.

    1999-05-01

    VY Canis Majoris is one of the most luminous known M supergiants. It is near the upper liminosity limit for cool stars on the HR Diagram. The optical star is partially obscured by its own circumstellar material. We present preliminary results of recent HST/WFPC2 optical imaging, and ground-based near-IR and mid-IR imaging of VY CMa and its circumstellar environment. We compare these results with previously obtained images of the related, but more evolved object IRC+10420 and discuss implications for their possible evolutionary and mass loss histories.

  3. HIGH-RESOLUTION INFRARED IMAGING AND SPECTROSCOPY OF THE Z CANIS MAJORIS SYSTEM DURING QUIESCENCE AND OUTBURST

    Energy Technology Data Exchange (ETDEWEB)

    Hinkley, Sasha; Hillenbrand, Lynne; Crepp, Justin R. [Department of Astronomy, California Institute of Technology, 1200 E. California Blvd, MC 249-17, Pasadena, CA 91125 (United States); Oppenheimer, Ben R.; Zimmerman, Neil; Brenner, Douglas [Astrophysics Department, American Museum of Natural History, Central Park West at 79th Street, New York, NY 10024 (United States); Rice, Emily L. [Department of Engineering Science and Physics, College of Staten Island, City University of New York, 2800 Victory Bvld, Staten Island, NY 10314 (United States); Pueyo, Laurent [Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218 (United States); Vasisht, Gautam; Roberts, Jennifer E.; Roberts, Lewis C. Jr.; Burruss, Rick; Wallace, J. Kent; Cady, Eric; Zhai, Chengxing [Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Dr., Pasadena, CA 91109 (United States); Kraus, Adam L. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA, 02138 (United States); Ireland, Michael J. [Department of Physics and Astronomy, Macquarie University, New South Wales, NSW 2109 (Australia); Beichman, Charles [NASA Exoplanet Science Institute, California Institute of Technology, Pasadena, CA 91125 (United States); Dekany, Richard [Caltech Optical Observatories, California Institute of Technology, Pasadena, CA 91125 (United States); Parry, Ian R. [Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom); and others

    2013-01-20

    We present adaptive optics photometry and spectra in the JHKL bands along with high spectral resolution K-band spectroscopy for each component of the Z Canis Majoris system. Our high angular resolution photometry of this very young ({approx}<1 Myr) binary, comprised of an FU Ori object and a Herbig Ae/Be star, was gathered shortly after the 2008 outburst while our high-resolution spectroscopy was gathered during a quiescent phase. Our photometry conclusively determines that the outburst was due solely to the embedded Herbig Ae/Be member, supporting results from earlier works, and that the optically visible FU Ori component decreased slightly ({approx}30%) in luminosity during the same period, consistent with previous works on the variability of FU Ori type systems. Further, our high-resolution K-band spectra definitively demonstrate that the 2.294 {mu}m CO absorption feature seen in composite spectra of the system is due solely to the FU Ori component, while a prominent CO emission feature at the same wavelength, long suspected to be associated with the innermost regions of a circumstellar accretion disk, can be assigned to the Herbig Ae/Be member. These findings clarify previous analyses of the origin of the CO emission in this complex system.

  4. VizieR Online Data Catalog: Spectrum of VY CMa in 220.65-224.25GHz range (Kaminski+, 2013)

    Science.gov (United States)

    Kaminski, T.; Gottlieb, C. A.; Menten, K. M.; Patel, N. A.; Young, K. H.; Brunken, S.; Muller, H. S. P.; McCarthy, M. C.; Winters, J. M.; Decin, L.

    2013-02-01

    A spectrum of VY Canis Majoris obtained with the Plateau de Bure Interferometer on 22 April and 13 October 2012 in the frequency range 220.65-224.25GHz. The interferometer was used in its D configuration with six antennas and the synthesized beam was 4.9x2.2-arcsec. The spectrum was extracted from the central pixel of the map obtained with the gridding of 0.65-arcsec. (2 data files).

  5. The ISO Long Wavelength Spectrometer line spectrum of VY Canis Majoris and other oxygen-rich evolved stars

    NARCIS (Netherlands)

    Polehampton, E. T.; Menten, K. M.; van der Tak, F. F. S.; White, G. J.

    Context. The far-infrared spectra of circumstellar envelopes around various oxygen-rich stars were observed using the ISO Long Wavelength Spectrometer (LWS). These have been shown to be spectrally rich, particularly in water lines, indicating a high H2O abundance. Aims. We have examined high

  6. Polarisation observations of VY Canis Majoris H2O 5 32-441 620.701 GHz maser emission with HIFI

    NARCIS (Netherlands)

    Harwit, M.; Houde, M.; Sonnentrucker, P.; Boogert, A. C. A.; Cernicharo, J.; De Beck, E.; Decin, L.; Henkel, C.; Higgins, R. D.; Jellema, W.; Kraus, A.; McCoey, C.; Melnick, G. J.; Menten, K. M.; Risacher, C.; Teyssier, D.; Vaillancourt, J. E.; Alcolea, J.; Bujarrabal, V.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A.P.; Olofsson, H.; Planesas, P.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L.B.F.M.

    2010-01-01

    Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims. We have aimed to elucidate the nature and structure

  7. HIFISTARS Herschel/HIFI observations of VY Canis Majoris. Molecular-line inventory of the envelope around the largest known star

    NARCIS (Netherlands)

    Alcolea, J.; Bujarrabal, V.; Planesas, P.; Teyssier, D.; Cernicharo, J.; De Beck, E.; Decin, L.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A.P.; Melnick, G.; Menten, K.M.; Neufeld, D.A.; Olofsson, H.; Schmidt, M.; Schöier, F.L.; Szczerba, R.; Waters, L.B.F.M.

    2013-01-01

    Aims. The study of the molecular gas in the circumstellar envelopes of evolved stars is normally undertaken by observing lines of CO (and other species) in the millimetre-wave domain. In general, the excitation requirements of the observed lines are low at these wavelengths, and therefore these

  8. Polarisation observations of VY Canis Majoris H2O 5(32)-4(41) 620.701 GHz maser emission with HIFI

    NARCIS (Netherlands)

    Harwit, M.; Houde, M.; Sonnentrucker, P.; Boogert, A. C. A.; Cernicharo, J.; de Beck, E.; Decin, L.; Henkel, C.; Higgins, R. D.; Jellema, W.; Kraus, A.; McCoey, C.; Melnick, G. J.; Menten, K. M.; Risacher, C.; Teyssier, D.; Vaillancourt, J. E.; Alcolea, J.; Bujarrabal, V.; Dominik, C.; Justtanont, K.; de Koter, A.; Marston, A. P.; Olofsson, H.; Planesas, P.; Schmidt, M.; Schöier, F. L.; Szczerba, R.; Waters, L. B. F. M.

    2010-01-01

    Context. Water vapour maser emission from evolved oxygen-rich stars remains poorly understood. Additional observations, including polarisation studies and simultaneous observation of different maser transitions may ultimately lead to greater insight. Aims. We have aimed to elucidate the nature and

  9. Red Supergiants as Potential Type IIn Supernova Progenitors: Spatially Resolved 4.6 μm CO Emission Around VY CMa and Betelgeuse

    Science.gov (United States)

    Smith, Nathan; Hinkle, Kenneth H.; Ryde, Nils

    2009-03-01

    We present high-resolution 4.6 μm CO spectra of the circumstellar environments of two red supergiants (RSGs) that are potential supernova (SN) progenitors: Betelgeuse and VY Canis Majoris (VY CMa). Around Betelgeuse, 12CO emission within ±3'' (±12 km s-1) follows a mildly clumpy but otherwise spherical shell, smaller than its ~55'' shell in K I λ7699. In stark contrast, 4.6 μm CO emission around VY CMa is coincident with bright K I in its clumpy asymmetric reflection nebula, within ±5'' (±40 km s-1) of the star. Our CO data reveal redshifted features not seen in K I spectra of VY CMa, indicating a more isotropic distribution of gas punctuated by randomly distributed asymmetric clumps. The relative CO and K I distribution in Betelgeuse arises from ionization effects within a steady wind, whereas in VY CMa, K I is emitted from skins of CO cloudlets resulting from episodic mass ejections 500-1000 yr ago. In both cases, CO and K I trace potential pre-SN circumstellar matter: we conclude that an extreme RSG like VY CMa might produce a Type IIn event like SN 1988Z if it were to explode in its current state, but Betelgeuse will not. VY CMa demonstrates that luminous blue variables are not necessarily the only progenitors of SNe IIn, but it underscores the requirement that SNe IIn suffer enhanced episodic mass loss shortly before exploding. Based on observations obtained at the Gemini Observatory.

  10. Distance and Kinematics of the Red Hypergiant VY CMa: Very Long Baseline Array and Very Large Array Astrometry

    Science.gov (United States)

    Zhang, B.; Reid, M. J.; Menten, K. M.; Zheng, X. W.

    2012-01-01

    We report astrometric results of phase-referencing very long baseline interferometry observations of 43 GHz SiO maser emission toward the red hypergiant VY Canis Majoris (VY CMa) using the Very Long Baseline Array (VLBA). We measured a trigonometric parallax of 0.83 ± 0.08 mas, corresponding to a distance of 1.20+0.13 -0.10 kpc. Compared to previous studies, the spatial distribution of SiO masers has changed dramatically, while its total extent remains similar. The internal motions of the maser spots are up to 1.4 mas yr-1, corresponding to 8 km s-1, and show a tendency for expansion. After modeling the expansion of maser spots, we derived an absolute proper motion for the central star of μ x = -2.8 ± 0.2 and μ y = 2.6 ± 0.2 mas yr-1 eastward and northward, respectively. Based on the maser distribution from the VLBA observations, and the relative position between the radio photosphere and the SiO maser emission at 43 GHz from the complementary Very Large Array observations, we estimate the absolute position of VY CMa at mean epoch 2006.53 to be αJ2000 = 07h22m58.s3259 ± 0.s0007, δJ2000 = -25°46'03farcs063 ± 0farcs010. The position and proper motion of VY CMa from the VLBA observations differ significantly with values measured by the Hipparcos satellite. These discrepancies are most likely associated with inhomogeneities and dust scattering the optical light in the circumstellar envelope. The absolute proper motion measured with VLBA suggests that VY CMa may be drifting out of the giant molecular cloud to the east of it.

  11. DISTANCE AND KINEMATICS OF THE RED HYPERGIANT VY CMa: VERY LONG BASELINE ARRAY AND VERY LARGE ARRAY ASTROMETRY

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, B. [Shanghai Astronomical Observatory, Chinese Academy of Sciences, Shanghai 200030 (China); Reid, M. J. [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Menten, K. M. [Max-Plank-Institut fuer Radioastronomie, Auf dem Huegel 69, 53121 Bonn (Germany); Zheng, X. W., E-mail: bzhang@mpifr.de [Department of Astronomy, Nanjing University, Nanjing 210093 (China)

    2012-01-01

    We report astrometric results of phase-referencing very long baseline interferometry observations of 43 GHz SiO maser emission toward the red hypergiant VY Canis Majoris (VY CMa) using the Very Long Baseline Array (VLBA). We measured a trigonometric parallax of 0.83 {+-} 0.08 mas, corresponding to a distance of 1.20{sup +0.13}{sub -0.10} kpc. Compared to previous studies, the spatial distribution of SiO masers has changed dramatically, while its total extent remains similar. The internal motions of the maser spots are up to 1.4 mas yr{sup -1}, corresponding to 8 km s{sup -1}, and show a tendency for expansion. After modeling the expansion of maser spots, we derived an absolute proper motion for the central star of {mu}{sub x} = -2.8 {+-} 0.2 and {mu}{sub y} = 2.6 {+-} 0.2 mas yr{sup -1} eastward and northward, respectively. Based on the maser distribution from the VLBA observations, and the relative position between the radio photosphere and the SiO maser emission at 43 GHz from the complementary Very Large Array observations, we estimate the absolute position of VY CMa at mean epoch 2006.53 to be {alpha}{sub J2000} = 07{sup h}22{sup m}58.{sup s}3259 {+-} 0.{sup s}0007, {delta}{sub J2000} = -25 Degree-Sign 46'03.''063 {+-} 0.''010. The position and proper motion of VY CMa from the VLBA observations differ significantly with values measured by the Hipparcos satellite. These discrepancies are most likely associated with inhomogeneities and dust scattering the optical light in the circumstellar envelope. The absolute proper motion measured with VLBA suggests that VY CMa may be drifting out of the giant molecular cloud to the east of it.

  12. DISTANCE AND KINEMATICS OF THE RED HYPERGIANT VY CMa: VERY LONG BASELINE ARRAY AND VERY LARGE ARRAY ASTROMETRY

    International Nuclear Information System (INIS)

    Zhang, B.; Reid, M. J.; Menten, K. M.; Zheng, X. W.

    2012-01-01

    We report astrometric results of phase-referencing very long baseline interferometry observations of 43 GHz SiO maser emission toward the red hypergiant VY Canis Majoris (VY CMa) using the Very Long Baseline Array (VLBA). We measured a trigonometric parallax of 0.83 ± 0.08 mas, corresponding to a distance of 1.20 +0.13 –0.10 kpc. Compared to previous studies, the spatial distribution of SiO masers has changed dramatically, while its total extent remains similar. The internal motions of the maser spots are up to 1.4 mas yr –1 , corresponding to 8 km s –1 , and show a tendency for expansion. After modeling the expansion of maser spots, we derived an absolute proper motion for the central star of μ x = –2.8 ± 0.2 and μ y = 2.6 ± 0.2 mas yr –1 eastward and northward, respectively. Based on the maser distribution from the VLBA observations, and the relative position between the radio photosphere and the SiO maser emission at 43 GHz from the complementary Very Large Array observations, we estimate the absolute position of VY CMa at mean epoch 2006.53 to be α J2000 = 07 h 22 m 58. s 3259 ± 0. s 0007, δ J2000 = –25°46'03.''063 ± 0.''010. The position and proper motion of VY CMa from the VLBA observations differ significantly with values measured by the Hipparcos satellite. These discrepancies are most likely associated with inhomogeneities and dust scattering the optical light in the circumstellar envelope. The absolute proper motion measured with VLBA suggests that VY CMa may be drifting out of the giant molecular cloud to the east of it.

  13. Spatially extended K Iλ7699 emission in the nebula of VY CMa: kinematics and geometry

    Science.gov (United States)

    Smith, Nathan

    2004-04-01

    Long-slit echelle spectra reveal bright extended emission from the K Iλ7699 resonance line in the reflection nebula surrounding the extreme red supergiant VY Canis Majoris. The central star has long been known for its unusually bright K I emission lines, but this is the first report of intrinsic emission from K I in the nebula. The extended emission is not just a reflected spectrum of the star, but is due to resonant scattering by K atoms in the outer nebula itself, and is therefore a valuable probe of the kinematics and geometry of the circumstellar environment of VY CMa. Dramatic velocity structure is seen in the long-slit spectra, and most lines of sight through the nebula intersect multiple distinct velocity components. A faint `halo' at large distances from the star does appear to show a reflected spectrum, however, and suggests a systemic velocity of +40 km s-1 with respect to the Sun. The most striking feature is blueshifted emission from the filled interior of a large shell seen in images; the kinematic structure is reminiscent of a Hubble flow, and provides strong evidence for asymmetric and episodic mass loss due to localized eruptions on the stellar surface.

  14. An Interferometric 270--355 GHz Spectral Line Survey of the Red Supergiant VY CMa

    Science.gov (United States)

    Menten, K. M.; Young, K. H.; Patel, N. A.; Gottlieb, C. A.; Thaddeus, P.; McCarthy, M. C.; Gurwell, M. A.; Belloche, A.; Kaminski, T.; Verheyen, L.; Decin, L.; Brunken, S.; Holger, S. P. M.

    2011-05-01

    We have used the Submillimeter Array to image the molecular line emission in the circumstellar envelope of the peculiar red supergiant star VY Canis Majoris over the whole 870 μm atmospheric window. Employing adaptive calibration using the object's continuum emission we achieve high quality one arcsecond resolution imaging of the whole 280--355 GHz range within which we find 211 distinct spectral lines from 33 molecules (including isotopologues) plus 40 unidentified lines. From the distribution of molecules we are obtaining their abundances and isotopologic abundance ratios. Using data for multiple transitions in a number of molecules we are deriving the physical conditions in the circumstellar envelope to reach a picture of the star's chemistry that can be compared with models. Our legacy survey is accompanied by a strong laboratory effort that helps with the identification of possibly newly found molecules traced by unidentified lines. We shall create a publicly accessible database of spectral-line channel-maps of the emission from all the lines detected in the survey.

  15. Erratum: ``Interferometric Observation of the Highly Polarized SiO Maser Emission from the v = 1, J = 5-4 Transition Associated with VY Canis Majoris'' (ApJ, 616, L47 [2004])

    Science.gov (United States)

    Shinnaga, Hiroko; Moran, James M.; Young, Ken H.; Ho, Paul T. P.

    2004-12-01

    Because of an error in transferring proof corrections, units for the 310 GHz flux were incorrectly given in Jy instead of mJy in § 3.3 of this Letter. In the first paragraph of § 3.3, the fourth sentence should correctly read: ``The fluxes at 301 and 658 GHz measured with the SMA recently were 340+/-10 mJy and 7.8+/-2.6 Jy, respectively.'' The Press sincerely regrets this error.

  16. Pre-main-sequence disk accretion in Z Canis Majoris

    International Nuclear Information System (INIS)

    Hartmann, L.; Kenyon, S.J.; Hewett, R.; Edwards, S.; Strom, K.M.; Strom, S.E.; Stauffer, J.R.

    1989-01-01

    It is suggested that the pre-main-sequence object Z CMa is a luminous accretion disk, similar in many respects to the FU Orionis variables. Z CMa shows the broad, doubled optical absorption lines expected from a rapidly rotating accretion disk. The first overtone CO absorption detected in Z CMa is blue-shifted, suggesting line formation in a disk wind. Accretion at rates about 0.001 solar mass/yr over 100 yr is required to explain the luminosity of Z CMa. The large amount of material accreted (0.1 solar mass/yr) indicates that Z CMa is in a very early stage of stellar evolution, possibly in an initial phase of massive disk accretion. 41 references

  17. The evolutionary state of the β Canis Majoris variables

    International Nuclear Information System (INIS)

    Shobbrook, R.R.

    1978-01-01

    It is found from accurate β photometry of bright stars in the region of the β CMa instability strip that about three-quarters of the stars in the strip, to a distance modulus of 8.0, are β CMa variables. The strip is not resolved by the data so that its intrinsic width is uncertain, but the conclusion from a consideration of theoretical evolutionary rates is that the variables must be very near the end of core hydrogen burning. Comparison of the relative positions of the empirical and theoretical instability strip and zero age main sequence indicates that the observationally located upper ZAMS is too bright. (author)

  18. Mass flow and evolution of UW Canis Majoris

    International Nuclear Information System (INIS)

    Kondo, Y.; Rahe, J.

    1979-01-01

    The far-UV spectrum of the eclipsing binary UW CMa (07f + 0-B) has earlier been utilized to derive a mass-loss rate of about 10 -6 to 10 -5 solar mass per year. The mass flow seems to be basically in the form of a stellar wing emanating from the 07f primary component, with radiation pressure as the controlling factor. The main characteristics that make UW CMa a possible progenitor of a Wolf-Rayet system are discussed. (Auth.)

  19. Pre-main-sequence disk accretion in Z Canis Majoris

    Science.gov (United States)

    Hartmann, L.; Kenyon, S. J.; Hewett, R.; Edwards, S.; Strom, K. M.; Strom, S. E.; Stauffer, J. R.

    1989-01-01

    It is suggested that the pre-main-sequence object Z CMa is a luminous accretion disk, similar in many respects to the FU Orionis variables. Z CMa shows the broad, doubled optical absorption lines expected from a rapidly rotating accretion disk. The first overtone CO absorption detected in Z CMa is blue-shifted, suggesting line formation in a disk wind. Accretion at rates about 0.001 solar mass/yr over 100 yr is required to explain the luminosity of Z CMa. The large amount of material accreted (0.1 solar mass/yr) indicates that Z CMa is in a very early stage of stellar evolution, possibly in an initial phase of massive disk accretion.

  20. A Study of Hypergiant Mass Loss in the Near-To-Mid Infrared: VY CMa, IRC +10420, mu Cep and rho Cas

    Science.gov (United States)

    Shenoy, Dinesh Prabhakar

    2016-01-01

    Stars of initial mass greater than 9 M_sun become red supergiants (RSGs), a short-lived stage during which they experience mass-loss that strongly influences their post-RSG evolution and end state. The highest luminosity RSGs, referred to here as hypergiants, experience episodic mass-loss whose mechanism remains poorly understood and motivates observations to help constrain it. This thesis studies mass loss from hypergiant stars with near-to-mid infrared imaging over a range of angular scales. The recent mass-loss history of the extreme red supergiant VY Canis Majoris and the warm hypergiant star IRC +10420 are studied at the sub-arcsecond scale with adaptive optics imaging and imaging polarimetry from 1 - 5 micron using LMIRCam on the Large Binocular Telescope (LBT) and MMT-Pol at the MMT Observatory. The nebular features of VY CMa are found to be highly polarized at 1.3 and 3.1 micron, with optically thick scattering required to reproduce the observed surface brightness. The flux of VY CMa's peculiar ``Southwest Clump'' is demonstrated to be due almost entirely to optically thick scattering, with little thermal emission, and with a lower limit mass of 5E-03 M_sun in this single feature. The imaging polarimetry of IRC +10420 at 2.2 micron resolves nebular emission with intrinsic polarization of 30%, with a high surface brightness indicating optically thick scattering largely in the plane of the sky. Using the polarimetry to constrain the scattered light emission, it is shown that the nebula's the emission is mostly thermal with a color temperature well above that for typical astrophysical dust. To probe further into hypergiants' history of mass-loss, mid-IR imaging with MMT/ MIRAC and SOFIA/FORCAST is used to study VY CMa, IRC +10420 and two additional hypergiants: the RSG mu Cep and the warm hypergiant rho Cas. Using DUSTY 1-D radiative transfer models, mu Cep's mass-loss rate is found to have declined by about a factor of 5 over a 13,000 history, ranging from 5E

  1. vy particles

    DEFF Research Database (Denmark)

    Hansen, Linda Vadgård; Thorarinsdottir, Thordis Linda; Gneiting, Tilmann

    to a von Mises–Fisher density, or uniform on a spherical cap, the correlation function of the associated random field admits a closed form expression. Using a Gaussian basis, the fractal or Hausdorff dimension of the surface of the Lévy particle reflects the decay of the correlation function at the origin...

  2. vy walks

    Science.gov (United States)

    Zaburdaev, V.; Denisov, S.; Klafter, J.

    2015-04-01

    Random walk is a fundamental concept with applications ranging from quantum physics to econometrics. Remarkably, one specific model of random walks appears to be ubiquitous across many fields as a tool to analyze transport phenomena in which the dispersal process is faster than dictated by Brownian diffusion. The Lévy-walk model combines two key features, the ability to generate anomalously fast diffusion and a finite velocity of a random walker. Recent results in optics, Hamiltonian chaos, cold atom dynamics, biophysics, and behavioral science demonstrate that this particular type of random walk provides significant insight into complex transport phenomena. This review gives a self-consistent introduction to Lévy walks, surveys their existing applications, including latest advances, and outlines further perspectives.

  3. Some aspects of Lévy copulas

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Lindner, A.M

    describe multivariate Lévy measures on Rm+. In this paper, we show that any such Lévy copula defines itself a Lévy measure with 1-stable margins, in a canonical way. A limit theorem is obtained, characterising convergence of Lévy measures with the aid of Lévy copulas. Homogeneous Lévy copulas...... are considered in detail. They correspond to Lévy processes which have a timeconstant Lévy copula. Furthermore, we show how the Lévy copula concept can be used to construct multivariate distributions in the Bondesson class with prescribed margins in the Bondesson class. The construction depends on a mapping ϒ...

  4. vy-driven queues

    NARCIS (Netherlands)

    Debicki, K.G.; Mandjes, M.R.H.

    2012-01-01

    This survey addresses the class of queues with Lévy input, which covers the classical M/G/1 queue and the reflected Brownian motion as special cases. First the stationary behavior is treated, with special attention to the case of the input process having one-sided jumps (i.e., spectrally one-sided

  5. vy flights in a box

    International Nuclear Information System (INIS)

    Iomin, Alexander

    2015-01-01

    Highlights: •A quantum Lévy process in a box involves topological constraints in space. •The eigenvalue problem is formulated for the Lévy process in the box. •The path integral formalism with the Lévy measure is constructed. •The evolution operator is obtained in the path integral presentation. -- Abstract: It is shown that a quantum Lévy process in a box leads to a problem involving topological constraints in space, and its treatment in the framework of the path integral formalism with the Lévy measure is suggested. The eigenvalue problem for the infinite potential well is properly defined and solved. An analytical expression for the evolution operator is obtained in the path integral presentation, and the path integral takes the correct limit of the local quantum mechanics with topological constraints. An example of the Lévy process in oscillating walls is also considered in the adiabatic approximation

  6. vy based Cox point processes

    DEFF Research Database (Denmark)

    Hellmund, Gunnar; Prokesová, Michaela; Jensen, Eva Bjørn Vedel

    2008-01-01

    In this paper we introduce Lévy-driven Cox point processes (LCPs) as Cox point processes with driving intensity function Λ defined by a kernel smoothing of a Lévy basis (an independently scattered, infinitely divisible random measure). We also consider log Lévy-driven Cox point processes (LLCPs......) with Λ equal to the exponential of such a kernel smoothing. Special cases are shot noise Cox processes, log Gaussian Cox processes, and log shot noise Cox processes. We study the theoretical properties of Lévy-based Cox processes, including moment properties described by nth-order product densities...

  7. Demodex canis: redescription and reevaluation.

    Science.gov (United States)

    Nutting, W B; Desch, C E

    1978-04-01

    A brief review of the taxonomy of Demodex canis is followed by a complete redescription. Demodex canis is diagnosed with D. odocoilei of the white-tailed deer. In view of the continued speculation that dogs and man share the same demodicid, simple morphological characters are noted which distinguish D. canis from D. folliculorum and D. brevis in all stages of their life cycles.

  8. Queues and Lévy Fluctuation Theory

    NARCIS (Netherlands)

    Dębicki, K.; Mandjes, M.

    2015-01-01

    The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades,

  9. Mass flow in the 07f binary UW Canis Majoris. II

    International Nuclear Information System (INIS)

    McCluskey, G.E. Jr.; Kondo, Y.

    1976-01-01

    The far-ultraviolet spectrum of the UW CMa was obtained from the Princeton telescope spectrometer on the Copernicus satellite at about phase 0.25 in order to supplement earlier observations of the same kind made near phase 0.75. Analysis of the data shows that the high-temperature gas giving rise to the P Cygni features in the far-ultraviolet spectrum is located primarily around the entire binary system and does not share in the motion of either component. The effects of radiation pressure on the Roche (Jacobian) equipotential surfaces and in generating a stellar wind are discussed

  10. vy matters VI Lévy-type processes moments, construction and heat kernel estimates

    CERN Document Server

    Kühn, Franziska

    2017-01-01

    Presenting some recent results on the construction and the moments of Lévy-type processes, the focus of this volume is on a new existence theorem, which is proved using a parametrix construction. Applications range from heat kernel estimates for a class of Lévy-type processes to existence and uniqueness theorems for Lévy-driven stochastic differential equations with Hölder continuous coefficients. Moreover, necessary and sufficient conditions for the existence of moments of Lévy-type processes are studied and some estimates on moments are derived. Lévy-type processes behave locally like Lévy processes but, in contrast to Lévy processes, they are not homogeneous in space. Typical examples are processes with varying index of stability and solutions of Lévy-driven stochastic differential equations. This is the sixth volume in a subseries of the Lecture Notes in Mathematics called Lévy Matters. Each volume describes a number of important topics in the theory or applicati ons of Lévy processes and pays ...

  11. vy-based growth models

    DEFF Research Database (Denmark)

    Jónsdóttir, Kristjana Ýr; Schmiegel, Jürgen; Jensen, Eva Bjørn Vedel

    2008-01-01

    In the present paper, we give a condensed review, for the nonspecialist reader, of a new modelling framework for spatio-temporal processes, based on Lévy theory. We show the potential of the approach in stochastic geometry and spatial statistics by studying Lévy-based growth modelling of planar o...... objects. The growth models considered are spatio-temporal stochastic processes on the circle. As a by product, flexible new models for space–time covariance functions on the circle are provided. An application of the Lévy-based growth models to tumour growth is discussed....

  12. Galactic water vapor emission: further observations of variability.

    Science.gov (United States)

    Knowles, S H; Mayer, C H; Sullivan, W T; Cheung, A C

    1969-10-10

    Recent observations of the 1.35-centimeter line emission of water vapor from galactic sources show short-term variability in the spectra of several sources. Two additional sources, Cygnus 1 and NGC 6334N, have been observed, and the spectra of W49 and VY Canis Majoris were measured over a wider range of radial velocity.

  13. Queues and Lévy fluctuation theory

    CERN Document Server

    Dębicki, Krzysztof

    2015-01-01

    The book provides an extensive introduction to queueing models driven by Lévy-processes as well as a systematic account of the literature on Lévy-driven queues. The objective is to make the reader familiar with the wide set of probabilistic techniques that have been developed over the past decades, including transform-based techniques, martingales, rate-conservation arguments, change-of-measure, importance sampling, and large deviations. On the application side, it demonstrates how Lévy traffic models arise when modelling current queueing-type systems (as communication networks) and includes applications to finance. Queues and Lévy Fluctuation Theory will appeal to graduate/postgraduate students and researchers in mathematics, computer science, and electrical engineering. Basic prerequisites are probability theory and stochastic processes.

  14. Molecular detection of Ehrlichia canis, Hepatozoon canis and Babesia canis vogeli in stray dogs in Mahasarakham province, Thailand.

    Science.gov (United States)

    Piratae, Supawadee; Pimpjong, Kiattisak; Vaisusuk, Kotchaphon; Chatan, Wasupon

    2015-01-01

    Canine tick borne diseases showing distribution worldwide have caused morbidity and mortality in dogs. This study observed the mainly tick borne pathogens described for dogs in Thailand, Ehrlichia canis, Hepatozoon canis and Babesia canis vogeli. From May to July 2014, blood samples were collected from 79 stray dogs from 7 districts of Mahasarakham province to molecular surveyed for 16s rRNA gene of E. canis and 18s rRNA gene of H. canis and B. canis vogeli. Twenty eight (35.44%) of stray dogs showed the infection with tick borne pathogens. The prevalence of E. canis infection was the highest with 21.5% (17/79). DNA of H. canis and B. canis vogeli were detected at the prevalence of 10.1% (8/79) and 6.3% (5/79), respectively. Co-infection between E. canis and B. canis vogeli were identified in 2 (2.5%) dogs. The results indicated that a wide range of tick borne pathogens are circulation in the canine population in Mahasarakham province. This study is the first report on prevalence of E. canis, H. canis and B. canis vogeli in stray dogs in Mahasarakham, a province in northern part of Thailand. This data providing is important to understand the prevalence of E. canis, H. canis and B. canis vogeli infection in stray dogs in this region, which will assist in the management of these blood parasite.

  15. A BVRCIC SURVEY OF W URSAE MAJORIS BINARIES

    International Nuclear Information System (INIS)

    Terrell, Dirk; Gross, John; Cooney, Walter R.

    2012-01-01

    We report on a BVR C I C survey of field W Ursae Majoris binary stars and present accurate colors for 606 systems that have been observed on at least three photometric nights from a robotic observatory in southern Arizona. Comparison with earlier photometry for a subset of the systems shows good agreement. We investigate two independent methods of determining the interstellar reddening, although both have limitations that can render them less effective than desired. A subset of 101 systems shows good agreement between the two reddening methods.

  16. Probability densities and Lévy densities

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler

    For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated.......For positive Lévy processes (i.e. subordinators) formulae are derived that express the probability density or the distribution function in terms of power series in time t. The applicability of the results to finance and to turbulence is briefly indicated....

  17. Recent observational evidence on W Ursae Majoris stars

    International Nuclear Information System (INIS)

    Rovithis-Livaniou, H.; Rovithis, P.

    1982-01-01

    During the last four years (1978-1981), some close binaries of W Ursae Majoris type have been observed from the National Observatory of Athens. In all cases a two-beam, multi-mode, nebular-stellar photometer has been used, attached to the 48-inch Cassegrain reflector at the Kryonerion Station. The observed systems are: 44i Boo, VW Cep, AB And, BV Dra, BW Dra, U Peg, V508 Oph. Especially VW Cep and 44i Boo, are very interesting objects; in addition to the light curves that have already been published (Rovithis and Rovithis-Livaniou, 1980-1981), other observations were obtained during the last year and are now at computational stage. The observations of these two systems will be continued during the next years. (Auth.)

  18. Fatal Babesia canis canis infection in a splenectomized Estonian dog.

    Science.gov (United States)

    Tiškina, Valentina; Capligina, Valentina; Must, Külli; Berzina, Inese; Ranka, Renate; Jokelainen, Pikka

    2016-01-25

    A previously splenectomized dog from Estonia was presented with a sudden lack of appetite and discoloration of the urine. Despite supportive therapy, its condition deteriorated dramatically during 1 day. Severe thrombocytopenia and high numbers of protozoan hemoparasites were evident in blood smears, and the hematocrit dropped from 46 to 33 %. The dog was euthanized before specific antibabesial treatment was initiated. Blood samples from the dog and from two other dogs in the same household tested positive for Babesia using molecular methods, and the sequences of partial 18S rRNA gene confirmed the causative species as Babesia canis canis. The risk of severe, rapidly progressing babesiosis in splenectomized dogs merits awareness.

  19. Dynamical continuous time random Lévy flights

    Science.gov (United States)

    Liu, Jian; Chen, Xiaosong

    2016-03-01

    The Lévy flights' diffusive behavior is studied within the framework of the dynamical continuous time random walk (DCTRW) method, while the nonlinear friction is introduced in each step. Through the DCTRW method, Lévy random walker in each step flies by obeying the Newton's Second Law while the nonlinear friction f(v) = - γ0v - γ2v3 being considered instead of Stokes friction. It is shown that after introducing the nonlinear friction, the superdiffusive Lévy flights converges, behaves localization phenomenon with long time limit, but for the Lévy index μ = 2 case, it is still Brownian motion.

  20. The Lévy-Itô decomposition in free probability

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Thorbjørnsen, Steen

    2005-01-01

    In this paper we prove the free analog of the Lévy-Itô decomposition for Lévy processes. A significant part of the proof consists of introducing free Poisson random measures, proving their existence and developing a theory of integration with respect to such measures. The existence of free Poisso...

  1. Probability measures, Lévy measures and analyticity in time

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Hubalek, Friedrich

    2008-01-01

    We investigate the relation of the semigroup probability density of an infinite activity Lévy process to the corresponding Lévy density. For subordinators, we provide three methods to compute the former from the latter. The first method is based on approximating compound Poisson distributions...

  2. Probability Measures, Lévy Measures, and Analyticity in Time

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole Eiler; Hubalek, Friedrich

    We investigate the relation of the semigroup probability density of an infinite activity Lévy process to the corresponding Lévy density. For subordinators we provide three methods to compute the former from the latter. The first method is based on approximating compound Poisson distributions...

  3. Applications of factorization embeddings for Lévy processes

    NARCIS (Netherlands)

    Dieker, A.B.

    2006-01-01

    We give three applications of the Pecherskii-Rogozin-Spitzer identity for Lévy processes. First, we find the joint distribution of the supremum and the epoch at which it is `attained' if a Lévy process has phase-type upward jumps. We also find the characteristics of the ladder process. Second, we

  4. Transient analysis of reflected Lévy processes

    NARCIS (Netherlands)

    Kella, O.; Mandjes, M.R.H.

    2013-01-01

    In this paper we establish a formula for the joint Laplace-Stieltjes transform of a reflected Lévy process and its regulator at an independent exponentially distributed time, starting at an independent exponentially distributed state. The Lévy process is general, that is, it is not assumed that it

  5. Transient analysis of reflected Lévy processes

    NARCIS (Netherlands)

    Kella, O.; Mandjes, M.

    2013-01-01

    In this paper, we establish a formula for the joint Laplace-Stieltjes transform of a reflected Lévy process and its regulator at an independent exponentially distributed time, starting at an independent exponentially distributed state. The Lévy process is general, that is, it is not assumed that it

  6. Shock-front compression of the magnetic field in the Canis Majoris R1 star-formation region

    International Nuclear Information System (INIS)

    Vrba, F.J.; Baierlein, R.; Herbst, W.; Wesleyan Univ., Middletown, CT; Van Vleck Observatory, Middletown, CT)

    1987-01-01

    Results are presented from a linear polarization survey at optical wavelengths of over 140 stars in the direction of the CMa R1 star-formation region; 26 of these are clearly associated with nebulosity within the area. The observations were obtained in order to test the argument of Herbst et al. (1978) that star formation in CMa R1 is driven by a shock wave from a nearby supernova (Herbs and Assousa, 1977 and 1978). The polarizations are found to be consistent with a simple model of the compression by a supernova-induced spherical shock front of an initially uniform interstellar magnetic field. The polarization vectors are inconsistent with a scenario of quiescent cloud collapse along magnetic-field lines. Multicolor polarimetry of the nebular stars provides evidence of grain growth toward increasing cloud optical depth, characterized by a ratio of total-to-selective extinction of R = 3.0 at E(B-V) = 0.23, increasing to R = 4.2 at E(B-V) = 0.7. 15 references

  7. Local clouds ionization, temperatures, electron densities and interfaces, from GHRS and IMAPS spectra of epsilon Canis Majoris

    CERN Document Server

    Gry, C; Gry, Cecile; Jenkins, Edward B.

    2001-01-01

    The composition and physical properties of several local clouds, including the Local Interstellar Cloud (LIC) in which the Sun is embedded, are derived from absorption features in the UV spectrum of the star epsilon CMa. We derive temperatures and densities for three components by combining our interpretations of the ionization balance of magnesium and the relative population of C II in an excited fine-structure level. We find that for the LIC n(e) = 0.12 +/-0.05 cm-3 and T = 7000 +/-1200 K. We derive the ionization fractions of hydrogen and discuss the ionizing processes. In particular the hydrogen and helium ionizations in the LIC are compatible with photoionization by the local EUV radiation fields from the hot stars and the cloud interface with the hot gas. We confirm the detection of high ionization species : Si III is detected in all clouds and C IV in two of them, including the LIC, suggesting the presence of ionized interfaces around the local clouds.

  8. Optical spectroscopy of Z Canis Majoris, V1057 Cygni, and FU Orionis - Accretion disks and signatures of disk winds

    Science.gov (United States)

    Welty, Alan D.; Strom, Stephen E.; Edwards, Suzan; Kenyon, Scott J.; Hartmann, Lee W.

    1992-01-01

    High resolution, high SNR optical spectra have been used to investigate the hypothesis that in outburst, FU Ori objects are self-luminous accretion disks whose light dominates at optical and near-IR wavelengths. Strong evidence has been found for linewidth versus wavelength correlation in good agreement with model predictions for Z CMa and V1057 Cyg, but not for FU Ori itself. Linewidth varies continuously with wavelength at optical wavelengths in the former two objects, In the case of FU Ori, it is argued that a combination of strong wind components to spectral lines, and surface gravity possibly being lower than that of supergiants, conceals the underlying linewidth versus wavelength relationship. A marginal correlation is found between linewidth and lower excitation potential in all three objects. Synthetic disk spectra are subtracted from observed spectral, and remarkably good fits are found for all three objects for wavelengths longer than about 5000 A.

  9. Infrared observations of circumstellar ammonia in OH/IR supergiants

    Science.gov (United States)

    Mclaren, R. A.; Betz, A. L.

    1980-01-01

    Ammonia has been detected in the circumstellar envelopes of VY Canis Majoris, VX Sagittarii, and IRC +10420 by means of several absorption lines in the nu-2 vibration-rotation band near 950 kaysers. The line profiles are well resolved (0.2 km/sec resolution) and show the gas being accelerated to terminal expansion velocities near 30 km/sec. The observations reveal a method for determining the position of the central star on VLBI maps of OH maser emission to an accuracy of approximately 0.2 arcsec. A firm lower limit of 2 x 10 to the 15th/sq cm is obtained for the NH3 column density in VY Canis Majoris.

  10. Infrared observations of circumstellar ammonia in OH/IR supergiants

    International Nuclear Information System (INIS)

    McLaren, R.A.; Betz, A.L.

    1980-01-01

    Ammonia has been detected in the circumstellar envelopes of VY Canis Majoris, VX Sagittarii, and IRC+10420 by means of several absorption lines in the ν 2 vibration-rotation band near 950 cm -1 . The line profiles are well resolved (0.2 km s -1 resolution) and show the gas being accelerated to terminal expansion velocities near 30 km s -1 . The observations reveal a method for determining the position of the central star on VLBI maps of OH maser emission to an accuracy of approx.0''.2. A firm lower limit of 2 x 10 15 cm -2 is obtained for the NH 3 column density in VY Canis Majoris

  11. Two coupled Lévy queues with independent input

    OpenAIRE

    Jevgenijs Ivanovs; Onno Boxma

    2014-01-01

    We consider a pair of coupled queues driven by independent spectrally-positive Lévy processes. With respect to the bi-variate workload process this framework includes both the coupled processor model and the two-server fluid network with independent Lévy inputs. We identify the joint transform of the stationary workload distribution in terms of Wiener-Hopf factors corresponding to two auxiliary Lévy processes with explicit Laplace exponents. We reinterpret and extend the ideas of Cohen and Bo...

  12. vy matters V functionals of Lévy processes

    CERN Document Server

    Andersen, Lars Nørvang; Aurzada, Frank; Glynn, Peter W; Maejima, Makoto; Pihlsgård, Mats; Simon, Thomas

    2015-01-01

    This three-chapter volume concerns the distributions of certain functionals of Lévy processes. The first chapter, by Makoto Maejima, surveys representations of the main sub-classes of infinitesimal distributions in terms of mappings of certain Lévy processes via stochastic integration. The second chapter, by Lars Nørvang Andersen, Søren Asmussen, Peter W. Glynn and Mats Pihlsgård, concerns Lévy processes reflected at two barriers, where reflection is formulated à la Skorokhod. These processes can be used to model systems with a finite capacity, which is crucial in many real life situations, a most important quantity being the overflow or the loss occurring at the upper barrier.  If a process is killed when crossing the boundary, a natural question concerns its lifetime. Deep formulas from fluctuation theory are the key to many classical results, which are reviewed in the third chapter by Frank Aurzada and Thomas Simon. The main part, however, discusses recent advances and developments in the setting w...

  13. Multidimensional Lévy walk and its scaling limits

    International Nuclear Information System (INIS)

    Teuerle, Marek; Magdziarz, Marcin; Żebrowski, Piotr

    2012-01-01

    In this paper we obtain the scaling limit of a multidimensional Lévy walk and describe the detailed structure of the limiting process. The scaling limit is a subordinated α-stable Lévy motion with the parent process and subordinator being strongly dependent processes. The corresponding Langevin picture is derived. We also introduce a useful method of simulating Lévy walks with a predefined spectral measure, which controls the direction of each jump. Our approach can be applied in the analysis of real-life data—we are able to recover the spectral measure from the data and obtain the full characterization of a Lévy walk. We also give examples of some useful spectral measures, which cover a large class of possible scenarios in the modeling of real-life phenomena. (paper)

  14. From Lévy-type processes to parabolic SPDEs

    CERN Document Server

    Quer-Sardanyons, Lluis

    2016-01-01

    This volume presents the lecture notes from two courses given by Davar Khoshnevisan and René Schilling, respectively, at the second Barcelona Summer School on Stochastic Analysis. René Schilling’s notes are an expanded version of his course on Lévy and Lévy-type processes, the purpose of which is two-fold: on the one hand, the course presents in detail selected properties of the Lévy processes, mainly as Markov processes, and their different constructions, eventually leading to the celebrated Lévy-Itô decomposition. On the other, it identifies the infinitesimal generator of the Lévy process as a pseudo-differential operator whose symbol is the characteristic exponent of the process, making it possible to study the properties of Feller processes as space inhomogeneous processes that locally behave like Lévy processes. The presentation is self-contained, and includes dedicated chapters that review Markov processes, operator semigroups, random measures, etc. In turn, Davar Khoshnevisan’s course inve...

  15. A note on inverses of non-decreasing Lévy processes

    NARCIS (Netherlands)

    J.A. Ferreira

    2001-01-01

    textabstractWe show that, apart from deterministic processes, compound Poisson processes with exponential jumps are the only (shifted) non-decreasing Lévy processes whose inverses are also (shifted) non-decreasing Lévy processes.

  16. vy matters IV estimation for discretely observed Lévy processes

    CERN Document Server

    Belomestny, Denis; Genon-Catalot, Valentine; Masuda, Hiroki; Reiß, Markus

    2015-01-01

    The aim of this volume is to provide an extensive account of the most recent advances in statistics for discretely observed Lévy processes. These days, statistics for stochastic processes is a lively topic, driven by the needs of various fields of application, such as finance, the biosciences, and telecommunication. The three chapters of this volume are completely dedicated to the estimation of Lévy processes, and are written by experts in the field. The first chapter by Denis Belomestny and Markus Reiß treats the low frequency situation, and estimation methods are based on the empirical characteristic function. The second chapter by Fabienne Comte and Valery Genon-Catalon is dedicated to non-parametric estimation mainly covering the high-frequency data case. A distinctive feature of this part is the construction of adaptive estimators, based on deconvolution or projection or kernel methods. The last chapter by Hiroki Masuda considers the parametric situation. The chapters cover the main aspects of the est...

  17. Detection of Babesia canis rossi, B. canis vogeli, and Hepatozoon canis in Dogs in a Village of Eastern Sudan by Using a Screening PCR and Sequencing Methodologies

    Science.gov (United States)

    Oyamada, Maremichi; Davoust, Bernard; Boni, Mickaël; Dereure, Jacques; Bucheton, Bruno; Hammad, Awad; Itamoto, Kazuhito; Okuda, Masaru; Inokuma, Hisashi

    2005-01-01

    Babesia and Hepatozoon infections of dogs in a village of eastern Sudan were analyzed by using a single PCR and sequencing. Among 78 dogs, 5 were infected with Babesia canis rossi and 2 others were infected with B. canis vogeli. Thirty-three dogs were positive for Hepatozoon. Hepatozoon canis was detected by sequence analysis. PMID:16275954

  18. Detection of Babesia canis rossi, B. canis vogeli, and Hepatozoon canis in dogs in a village of eastern Sudan by using a screening PCR and sequencing methodologies.

    Science.gov (United States)

    Oyamada, Maremichi; Davoust, Bernard; Boni, Mickaël; Dereure, Jacques; Bucheton, Bruno; Hammad, Awad; Itamoto, Kazuhito; Okuda, Masaru; Inokuma, Hisashi

    2005-11-01

    Babesia and Hepatozoon infections of dogs in a village of eastern Sudan were analyzed by using a single PCR and sequencing. Among 78 dogs, 5 were infected with Babesia canis rossi and 2 others were infected with B. canis vogeli. Thirty-three dogs were positive for Hepatozoon. Hepatozoon canis was detected by sequence analysis.

  19. Detection of Babesia canis rossi, B. canis vogeli, and Hepatozoon canis in Dogs in a Village of Eastern Sudan by Using a Screening PCR and Sequencing Methodologies

    OpenAIRE

    Oyamada, Maremichi; Davoust, Bernard; Boni, Mickaël; Dereure, Jacques; Bucheton, Bruno; Hammad, Awad; Itamoto, Kazuhito; Okuda, Masaru; Inokuma, Hisashi

    2005-01-01

    Babesia and Hepatozoon infections of dogs in a village of eastern Sudan were analyzed by using a single PCR and sequencing. Among 78 dogs, 5 were infected with Babesia canis rossi and 2 others were infected with B. canis vogeli. Thirty-three dogs were positive for Hepatozoon. Hepatozoon canis was detected by sequence analysis.

  20. A geometric theory for Lévy distributions

    International Nuclear Information System (INIS)

    Eliazar, Iddo

    2014-01-01

    vy distributions are of prime importance in the physical sciences, and their universal emergence is commonly explained by the Generalized Central Limit Theorem (CLT). However, the Generalized CLT is a geometry-less probabilistic result, whereas physical processes usually take place in an embedding space whose spatial geometry is often of substantial significance. In this paper we introduce a model of random effects in random environments which, on the one hand, retains the underlying probabilistic structure of the Generalized CLT and, on the other hand, adds a general and versatile underlying geometric structure. Based on this model we obtain geometry-based counterparts of the Generalized CLT, thus establishing a geometric theory for Lévy distributions. The theory explains the universal emergence of Lévy distributions in physical settings which are well beyond the realm of the Generalized CLT

  1. A geometric theory for Lévy distributions

    Science.gov (United States)

    Eliazar, Iddo

    2014-08-01

    vy distributions are of prime importance in the physical sciences, and their universal emergence is commonly explained by the Generalized Central Limit Theorem (CLT). However, the Generalized CLT is a geometry-less probabilistic result, whereas physical processes usually take place in an embedding space whose spatial geometry is often of substantial significance. In this paper we introduce a model of random effects in random environments which, on the one hand, retains the underlying probabilistic structure of the Generalized CLT and, on the other hand, adds a general and versatile underlying geometric structure. Based on this model we obtain geometry-based counterparts of the Generalized CLT, thus establishing a geometric theory for Lévy distributions. The theory explains the universal emergence of Lévy distributions in physical settings which are well beyond the realm of the Generalized CLT.

  2. Optimal stopping and perpetual options for Lévy processes

    OpenAIRE

    Ernesto Mordecki

    2002-01-01

    Consider a model of a financial market with a stock driven by a Lévy process and constant interest rate. A closed formula for prices of perpetual American call options in terms of the overall supremum of the Lévy process, and a corresponding closed formula for perpetual American put options involving the infimum of the after-mentioned process are obtained. As a direct application of the previous results, a Black-Scholes type formula is given. Also as a consequence, simple explicit formulas fo...

  3. Modelling energy spot prices by Lévy semistationary processes

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole; Benth, Fred Espen; Veraart, Almut

    This paper introduces a new modelling framework for energy spot prices based on Lévy semistationary processes. Lévy semistationary processes are special cases of the general class of ambit processes. We provide a detailed analysis of the probabilistic properties of such models and we show how...... they are able to capture many of the stylised facts observed in energy markets. Furthermore, we derive forward prices based on our spot price model. As it turns out, many of the classical spot models can be embedded into our novel modelling framework....

  4. Subexponential loss rate asymptotics for Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang

    2011-01-01

    We consider a Lévy process reflected in barriers at 0 and K > 0. The loss rate is the mean of the local time at K at time 1 when the process is started in stationarity, and is a natural continuous-time analogue of the stationary expected loss rate for a reflected random walk. We derive asymptotic...... for the loss rate when K tends to infinity, when the mean of the Lévy process is negative and the positive jumps are subexponential. In the course of this derivation, we achieve a formula, which is a generalization of the celebrated Pollaczeck-Khinchine formula....

  5. Hot spot in eclipsing dwarf nova IY Ursae Majoris during quiescence and normal outburst

    OpenAIRE

    Bakowska, K.; Olech, A.

    2016-01-01

    We present the analysis of hot spot brightness in light curves of the eclipsing dwarf nova IY Ursae Majoris during its normal outburst in March 2013 and in quiescence in April 2012 and in October 2015. Examination of four reconstructed light curves of the hot spot eclipses showed directly that the brightness of the hot spot changed significantly only during the outburst. The brightness of the hot spot, before and after the outburst, was on the same level. Hereby, based on the behaviour of the...

  6. Identification of Babesia canis genotypes in dogs from Lithuania

    OpenAIRE

    Tamoliūnaitė, Dovilė; Radzijevskaja, Jana; Paulauskas, Algimantas; Sabūnas, Vytautas; Karvelienė, Birutė; Zamokas, Gintaras

    2018-01-01

    Canine babesiosis is a widespread tick-borne disease caused by haematozoan parasites of the genus Babesia. The vast majority of clinical babesiosis cases in dogs in Europe is caused by Babesia canis. Canine babesiosis has become quite frequent in Lithuania during the past decade. Babesiosis caused by B. canis may range from mild to severe disease in dogs. Such difference in the virulence of B. canis strains is associated with genetic heterogeneity among B. canis strains. We aimed to investiga...

  7. vy Walks Suboptimal under Predation Risk.

    Directory of Open Access Journals (Sweden)

    Masato S Abe

    2015-11-01

    Full Text Available A key challenge in movement ecology is to understand how animals move in nature. Previous studies have predicted that animals should perform a special class of random walks, called Lévy walk, to obtain more targets. However, some empirical studies did not support this hypothesis, and the relationship between search strategy and ecological factors is still unclear. We focused on ecological factors, such as predation risk, and analyzed whether Lévy walk may not be favored. It was remarkable that the ecological factors often altered an optimal search strategy from Lévy walk to Brownian walk, depending on the speed of the predator's movement, density of predators, etc. This occurred because higher target encounter rates simultaneously led searchers to higher predation risks. Our findings indicate that animals may not perform Lévy walks often, and we suggest that it is crucial to consider the ecological context for evaluating the search strategy performed by animals in the field.

  8. vy Walks Suboptimal under Predation Risk

    Science.gov (United States)

    Abe, Masato S.; Shimada, Masakazu

    2015-01-01

    A key challenge in movement ecology is to understand how animals move in nature. Previous studies have predicted that animals should perform a special class of random walks, called Lévy walk, to obtain more targets. However, some empirical studies did not support this hypothesis, and the relationship between search strategy and ecological factors is still unclear. We focused on ecological factors, such as predation risk, and analyzed whether Lévy walk may not be favored. It was remarkable that the ecological factors often altered an optimal search strategy from Lévy walk to Brownian walk, depending on the speed of the predator’s movement, density of predators, etc. This occurred because higher target encounter rates simultaneously led searchers to higher predation risks. Our findings indicate that animals may not perform Lévy walks often, and we suggest that it is crucial to consider the ecological context for evaluating the search strategy performed by animals in the field. PMID:26544687

  9. Transient error approximation in a Lévy queue

    NARCIS (Netherlands)

    Mathijsen, B.; Zwart, A.P.

    2017-01-01

    Motivated by a capacity allocation problem within a finite planning period, we conduct a transient analysis of a single-server queue with Lévy input. From a cost minimization perspective, we investigate the error induced by using stationary congestion measures as opposed to time-dependent measures.

  10. On spatio-temporal Lévy based Cox processes

    DEFF Research Database (Denmark)

    Prokesova, Michaela; Hellmund, Gunnar; Jensen, Eva Bjørn Vedel

    2006-01-01

    The paper discusses a new class of models for spatio-temporal Cox point processes. In these models, the driving field is defined by means of an integral of a weight function with respect to a Lévy basis. The relations to other Cox process models studied previously are discussed and formulas for t...

  11. Structural properties of reflected Lévy processes

    DEFF Research Database (Denmark)

    Andersen, Lars Nørvang; Mandjes, Michel

    This paper considers a number of structural properties of reflected Lévy processes, where both one-sided reflection (at 0) and two-sided reflection (at both 0 and K > 0) are examined. With Vt being the position of the reflected process at time t, we focus on the analysis of ζ(t) := EVt and ξ(t) :...

  12. Representations of homogeneous quantum Lévy fields

    Indian Academy of Sciences (India)

    is a natural algebraic way of defining dimension free, covariant quantum ... Lévy fields [2] parametrised by x ∈ R+ × Rd instead of t ∈ R+ are particular interesting ...... [7] Heyer H, Generation and representation of convolution hemigroups on a ...

  13. vy diffusion: the density versus the trajectory approach

    International Nuclear Information System (INIS)

    Bologna, M; Grigolini, P

    2009-01-01

    We discuss the problem of deriving Lévy diffusion, in the form of a Lévy walk, from a density approach, namely using a Liouville equation. We address this problem for a case that has already been discussed using the method of the continuous time random walk, and consequently an approach based on trajectory dynamics rather than density time evolution. We show that the use of the Liouville equation requires the knowledge of the correlation functions of the fluctuation that generates the Lévy diffusion. We benefit from the results of earlier work proving that the correlation function is not factorized as in the Poisson case. We show that the Liouville equation generates a long-time diffusion whose probability distribution density keeps a memory of the detailed form of the fluctuation correlation function, and not only of its long-time inverse power law structure. Although the main result of this paper rests on an approximate expression for higher-order correlation functions, it becomes exact in the long-time limit. Thus, we argue that it explains the failure to derive Lévy diffusion from the Liouville equation, thereby supporting the claim that there exists a conflict between trajectory and density approaches in this case

  14. Environmental context explains Lévy and Brownian movement patterns of marine predators.

    Science.gov (United States)

    Humphries, Nicolas E; Queiroz, Nuno; Dyer, Jennifer R M; Pade, Nicolas G; Musyl, Michael K; Schaefer, Kurt M; Fuller, Daniel W; Brunnschweiler, Juerg M; Doyle, Thomas K; Houghton, Jonathan D R; Hays, Graeme C; Jones, Catherine S; Noble, Leslie R; Wearmouth, Victoria J; Southall, Emily J; Sims, David W

    2010-06-24

    An optimal search theory, the so-called Lévy-flight foraging hypothesis, predicts that predators should adopt search strategies known as Lévy flights where prey is sparse and distributed unpredictably, but that Brownian movement is sufficiently efficient for locating abundant prey. Empirical studies have generated controversy because the accuracy of statistical methods that have been used to identify Lévy behaviour has recently been questioned. Consequently, whether foragers exhibit Lévy flights in the wild remains unclear. Crucially, moreover, it has not been tested whether observed movement patterns across natural landscapes having different expected resource distributions conform to the theory's central predictions. Here we use maximum-likelihood methods to test for Lévy patterns in relation to environmental gradients in the largest animal movement data set assembled for this purpose. Strong support was found for Lévy search patterns across 14 species of open-ocean predatory fish (sharks, tuna, billfish and ocean sunfish), with some individuals switching between Lévy and Brownian movement as they traversed different habitat types. We tested the spatial occurrence of these two principal patterns and found Lévy behaviour to be associated with less productive waters (sparser prey) and Brownian movements to be associated with productive shelf or convergence-front habitats (abundant prey). These results are consistent with the Lévy-flight foraging hypothesis, supporting the contention that organism search strategies naturally evolved in such a way that they exploit optimal Lévy patterns.

  15. Asymmetric Lévy flight in financial ratios.

    Science.gov (United States)

    Podobnik, Boris; Valentinčič, Aljoša; Horvatić, Davor; Stanley, H Eugene

    2011-11-01

    Because financial crises are characterized by dangerous rare events that occur more frequently than those predicted by models with finite variances, we investigate the underlying stochastic process generating these events. In the 1960s Mandelbrot [Mandelbrot B (1963) J Bus 36:394-419] and Fama [Fama EF (1965) J Bus 38:34-105] proposed a symmetric Lévy probability distribution function (PDF) to describe the stochastic properties of commodity changes and price changes. We find that an asymmetric Lévy PDF, L, characterized by infinite variance, models several multiple credit ratios used in financial accounting to quantify a firm's financial health, such as the Altman [Altman EI (1968) J Financ 23:589-609] Z score and the Zmijewski [Zmijewski ME (1984) J Accounting Res 22:59-82] score, and models changes of individual financial ratios, ΔX(i). We thus find that Lévy PDFs describe both the static and dynamics of credit ratings. We find that for the majority of ratios, ΔX(i) scales with the Lévy parameter α ≈ 1, even though only a few of the individual ratios are characterized by a PDF with power-law tails X(i)(-1-α) with infinite variance. We also find that α exhibits a striking stability over time. A key element in estimating credit losses is the distribution of credit rating changes, the functional form of which is unknown for alphabetical ratings. For continuous credit ratings, the Altman Z score, we find that P(ΔZ) follows a Lévy PDF with power-law exponent α ≈ 1, consistent with changes of individual financial ratios. Estimating the conditional P(ΔZ|Z) versus Z, we demonstrate how this continuous credit rating approach and its dynamics can be used to evaluate credit risk.

  16. Babesia canis vogeli, Ehrlichia canis, and Anaplasma platys infection in a dog.

    Science.gov (United States)

    Al Izzi, Salah; Martin, Donald S; Chan, Roxanne Y Y; Leutenegger, Christian M

    2013-12-01

    A 12-month-old male neutered mixed breed dog was presented with a history of diarrhea, lethargy, emaciation, polydypsia, and sniffling. Physical examination findings included pale mucous membranes, increased heart and respiratory rates, and normal rectal temperature (38°C). Hematologic abnormalities included anemia and thrombocytopenia. Biochemical abnormalities included hypoalbuminemia, hyperbilirubinemia, and elevated ALP and ALT activities. A SNAP 4Dx test result was positive for Ehrlichia canis. Babesia canis vogeli organisms were found in the peripheral blood films, while morulae of E canis were not seen. Real-time polymerase chain reaction testing confirmed the presence of both B c vogeli and E canis organisms, and also was positive for Anaplasma platys infection. The dog recovered following treatment with doxycycline and imidocarb dipropionate, with normal hematology and biochemical profiles. © 2013 American Society for Veterinary Clinical Pathology.

  17. Mixed Ehrlichia canis, Hepatozoon canis, and presumptive Anaplasma phagocytophilum infection in a dog.

    Science.gov (United States)

    Mylonakis, Mathio E; Koutinas, Alex F; Baneth, Gad; Polizopoulou, Zoe; Fytianou, Anna

    2004-01-01

    A 5-month-old, female, mongrel dog was admitted to the Clinic of Companion Animal Medicine, Aristotle University of Thessaloniki, Greece, with depression, anorexia, fever, peripheral lymphadenopathy, splenomegaly, oculonasal discharge, nonregenerative anemia, and mild thrombocytopenia. Cytology of Giemsa-stained buffy coat, bone marrow, and lymph node aspiration smears revealed numerous morulae in mononuclear leukocytes and in neutrophils, and Hepatozoon canis gamonts in neutrophils. The dog was seropositive to Ehrlichia canis (immunofluorescence assay [IFA]) and Hepatozoon canis (ELISA) but not to Anaplasma phagocytophilum (IFA). A nested polymerase chain reaction performed on bone marrow aspirates was positive for E canis. This method was not applied for the detection of A phagocytophilum. Treatment with doxycycline and imidocarb dipropionate resulted in both clinical and parasitologic cure. This is the first reported case of a mixed infection with E canis, H canis, and presumptive A phagocytophilum. The findings emphasize the value of cytology in offering a quick and inexpensive diagnosis in mixed tick-borne infections of dogs.

  18. The mitochondrial genome of Toxocara canis.

    Science.gov (United States)

    Jex, Aaron R; Waeschenbach, Andrea; Littlewood, D Timothy J; Hu, Min; Gasser, Robin B

    2008-08-06

    Toxocara canis (Ascaridida: Nematoda), which parasitizes (at the adult stage) the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provide genetic markers for investigations in these areas, but complete mitochondrial genomic data have been lacking for T. canis and its congeners. In the present study, the mitochondrial genome of T. canis was amplified by long-range polymerase chain reaction (long PCR) and sequenced using a primer-walking strategy. This circular mitochondrial genome was 14162 bp and contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for secementean nematodes, including Ascaris suum and Anisakis simplex (Ascaridida). The mitochondrial genome of T. canis provides genetic markers for studies into the systematics, population genetics and epidemiology of this zoonotic parasite and its congeners. Such markers can now be used in prospecting for cryptic species and for exploring host specificity and zoonotic potential, thus underpinning the prevention and control of toxocariasis in humans and other hosts.

  19. The mitochondrial genome of Toxocara canis.

    Directory of Open Access Journals (Sweden)

    Aaron R Jex

    2008-08-01

    Full Text Available Toxocara canis (Ascaridida: Nematoda, which parasitizes (at the adult stage the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provide genetic markers for investigations in these areas, but complete mitochondrial genomic data have been lacking for T. canis and its congeners. In the present study, the mitochondrial genome of T. canis was amplified by long-range polymerase chain reaction (long PCR and sequenced using a primer-walking strategy. This circular mitochondrial genome was 14162 bp and contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for secementean nematodes, including Ascaris suum and Anisakis simplex (Ascaridida. The mitochondrial genome of T. canis provides genetic markers for studies into the systematics, population genetics and epidemiology of this zoonotic parasite and its congeners. Such markers can now be used in prospecting for cryptic species and for exploring host specificity and zoonotic potential, thus underpinning the prevention and control of toxocariasis in humans and other hosts.

  20. The Mitochondrial Genome of Toxocara canis

    Science.gov (United States)

    Littlewood, D. Timothy J.; Hu, Min; Gasser, Robin B.

    2008-01-01

    Toxocara canis (Ascaridida: Nematoda), which parasitizes (at the adult stage) the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provide genetic markers for investigations in these areas, but complete mitochondrial genomic data have been lacking for T. canis and its congeners. In the present study, the mitochondrial genome of T. canis was amplified by long-range polymerase chain reaction (long PCR) and sequenced using a primer-walking strategy. This circular mitochondrial genome was 14162 bp and contained 12 protein-coding, 22 transfer RNA, and 2 ribosomal RNA genes consistent for secernentean nematodes, including Ascaris suum and Anisakis simplex (Ascaridida). The mitochondrial genome of T. canis provides genetic markers for studies into the systematics, population genetics and epidemiology of this zoonotic parasite and its congeners. Such markers can now be used in prospecting for cryptic species and for exploring host specificity and zoonotic potential, thus underpinning the prevention and control of toxocariasis in humans and other hosts. PMID:18682828

  1. Diffusion limit of Lévy-Lorentz gas is Brownian motion

    Science.gov (United States)

    Magdziarz, Marcin; Szczotka, Wladyslaw

    2018-07-01

    In this paper we analyze asymptotic behaviour of a stochastic process called Lévy-Lorentz gas. This process is aspecial kind of continuous-time random walk in which walker moves in the fixed environment composed of scattering points. Upon each collision the walker performs a flight to the nearest scattering point. This type of dynamics is observed in Lévy glasses or long quenched polymers. We show that the diffusion limit of Lévy-Lorentz gas with finite mean distance between scattering centers is the standard Brownian motion. Thus, for long times the behaviour of the Lévy-Lorentz gas is close to the diffusive regime.

  2. Stationary distribution and ergodicity of a stochastic food-chain model with Lévy jumps

    Science.gov (United States)

    Yu, Jingyi; Liu, Meng

    2017-09-01

    In this paper, a three-species stochastic food-chain model with Lévy jumps is proposed and analyzed. Sharp sufficient criteria for the existence and uniqueness of an ergodic stationary distribution are established. The effects of Lévy jumps on the existence of the stationary distribution are revealed: in some cases, the Lévy jumps could make the stationary distribution appear, while in some cases, the Lévy jumps could make the stationary distribution disappear. Some numerical simulations are introduced to illustrate the theoretical results.

  3. vy processes on a generalized fractal comb

    Science.gov (United States)

    Sandev, Trifce; Iomin, Alexander; Méndez, Vicenç

    2016-09-01

    Comb geometry, constituted of a backbone and fingers, is one of the most simple paradigm of a two-dimensional structure, where anomalous diffusion can be realized in the framework of Markov processes. However, the intrinsic properties of the structure can destroy this Markovian transport. These effects can be described by the memory and spatial kernels. In particular, the fractal structure of the fingers, which is controlled by the spatial kernel in both the real and the Fourier spaces, leads to the Lévy processes (Lévy flights) and superdiffusion. This generalization of the fractional diffusion is described by the Riesz space fractional derivative. In the framework of this generalized fractal comb model, Lévy processes are considered, and exact solutions for the probability distribution functions are obtained in terms of the Fox H-function for a variety of the memory kernels, and the rate of the superdiffusive spreading is studied by calculating the fractional moments. For a special form of the memory kernels, we also observed a competition between long rests and long jumps. Finally, we considered the fractal structure of the fingers controlled by a Weierstrass function, which leads to the power-law kernel in the Fourier space. This is a special case, when the second moment exists for superdiffusion in this competition between long rests and long jumps.

  4. Human memory retrieval as Lévy foraging

    Science.gov (United States)

    Rhodes, Theo; Turvey, Michael T.

    2007-11-01

    When people attempt to recall as many words as possible from a specific category (e.g., animal names) their retrievals occur sporadically over an extended temporal period. Retrievals decline as recall progresses, but short retrieval bursts can occur even after tens of minutes of performing the task. To date, efforts to gain insight into the nature of retrieval from this fundamental phenomenon of semantic memory have focused primarily upon the exponential growth rate of cumulative recall. Here we focus upon the time intervals between retrievals. We expected and found that, for each participant in our experiment, these intervals conformed to a Lévy distribution suggesting that the Lévy flight dynamics that characterize foraging behavior may also characterize retrieval from semantic memory. The closer the exponent on the inverse square power-law distribution of retrieval intervals approximated the optimal foraging value of 2, the more efficient was the retrieval. At an abstract dynamical level, foraging for particular foods in one's niche and searching for particular words in one's memory must be similar processes if particular foods and particular words are randomly and sparsely located in their respective spaces at sites that are not known a priori. We discuss whether Lévy dynamics imply that memory processes, like foraging, are optimized in an ecological way.

  5. vy processes on a generalized fractal comb

    International Nuclear Information System (INIS)

    Sandev, Trifce; Iomin, Alexander; Méndez, Vicenç

    2016-01-01

    Comb geometry, constituted of a backbone and fingers, is one of the most simple paradigm of a two-dimensional structure, where anomalous diffusion can be realized in the framework of Markov processes. However, the intrinsic properties of the structure can destroy this Markovian transport. These effects can be described by the memory and spatial kernels. In particular, the fractal structure of the fingers, which is controlled by the spatial kernel in both the real and the Fourier spaces, leads to the Lévy processes (Lévy flights) and superdiffusion. This generalization of the fractional diffusion is described by the Riesz space fractional derivative. In the framework of this generalized fractal comb model, Lévy processes are considered, and exact solutions for the probability distribution functions are obtained in terms of the Fox H -function for a variety of the memory kernels, and the rate of the superdiffusive spreading is studied by calculating the fractional moments. For a special form of the memory kernels, we also observed a competition between long rests and long jumps. Finally, we considered the fractal structure of the fingers controlled by a Weierstrass function, which leads to the power-law kernel in the Fourier space. This is a special case, when the second moment exists for superdiffusion in this competition between long rests and long jumps. (paper)

  6. vy flight artificial bee colony algorithm

    Science.gov (United States)

    Sharma, Harish; Bansal, Jagdish Chand; Arya, K. V.; Yang, Xin-She

    2016-08-01

    Artificial bee colony (ABC) optimisation algorithm is a relatively simple and recent population-based probabilistic approach for global optimisation. The solution search equation of ABC is significantly influenced by a random quantity which helps in exploration at the cost of exploitation of the search space. In the ABC, there is a high chance to skip the true solution due to its large step sizes. In order to balance between diversity and convergence in the ABC, a Lévy flight inspired search strategy is proposed and integrated with ABC. The proposed strategy is named as Lévy Flight ABC (LFABC) has both the local and global search capability simultaneously and can be achieved by tuning the Lévy flight parameters and thus automatically tuning the step sizes. In the LFABC, new solutions are generated around the best solution and it helps to enhance the exploitation capability of ABC. Furthermore, to improve the exploration capability, the numbers of scout bees are increased. The experiments on 20 test problems of different complexities and five real-world engineering optimisation problems show that the proposed strategy outperforms the basic ABC and recent variants of ABC, namely, Gbest-guided ABC, best-so-far ABC and modified ABC in most of the experiments.

  7. Fluctuations of Lévy processes with applications introductory lectures

    CERN Document Server

    Kyprianou, Andreas E

    2014-01-01

    vy processes are the natural continuous-time analogue of random walks and form a rich class of stochastic processes around which a robust mathematical theory exists. Their application appears in the theory of many areas of classical and modern stochastic processes including storage models, renewal processes, insurance risk models, optimal stopping problems, mathematical finance, continuous-state branching processes and positive self-similar Markov processes. This textbook is based on a series of graduate courses concerning the theory and application of Lévy processes from the perspective of their path fluctuations. Central to the presentation is the decomposition of paths in terms of excursions from the running maximum as well as an understanding of short- and long-term behaviour. The book aims to be mathematically rigorous while still providing an intuitive feel for underlying principles. The results and applications often focus on the case of Lévy processes with jumps in only one direction, for which r...

  8. Synchronisation under shocks: The Lévy Kuramoto model

    Science.gov (United States)

    Roberts, Dale; Kalloniatis, Alexander C.

    2018-04-01

    We study the Kuramoto model of identical oscillators on Erdős-Rényi (ER) and Barabasi-Alberts (BA) scale free networks examining the dynamics when perturbed by a Lévy noise. Lévy noise exhibits heavier tails than Gaussian while allowing for their tempering in a controlled manner. This allows us to understand how 'shocks' influence individual oscillator and collective system behaviour of a paradigmatic complex system. Skewed α-stable Lévy noise, equivalent to fractional diffusion perturbations, are considered, but overlaid by exponential tempering of rate λ. In an earlier paper we found that synchrony takes a variety of forms for identical Kuramoto oscillators subject to stable Lévy noise, not seen for the Gaussian case, and changing with α: a noise-induced drift, a smooth α dependence of the point of cross-over of synchronisation point of ER and BA networks, and a severe loss of synchronisation at low values of α. In the presence of tempering we observe both analytically and numerically a dramatic change to the α synchronisation is sustained over a larger range of values of the 'noise strength' σ, improved compared to the α > 1 tempered cases. Analytically we study the system close to the phase synchronised fixed point and solve the tempered fractional Fokker-Planck equation. There we observe that densities show stronger support in the basin of attraction at low α for fixed coupling, σ and tempering λ. We then perform numerical simulations for networks of size N = 1000 and average degree d ¯ = 10. There, we compute the order parameter r as a function of σ for fixed α and λ and observe values of r ≈ 1 over larger ranges of σ for α synchronisation down to low values of α. We propose a mechanism for this in terms of the basic shape of the tempered stable Lévy densities for various α and how it feeds into Kuramoto oscillator dynamics and illustrate this with examples of specific paths.

  9. A T8.5 BROWN DWARF MEMBER OF THE ξ URSAE MAJORIS SYSTEM

    International Nuclear Information System (INIS)

    Wright, Edward L.; Mace, Gregory; McLean, Ian S.; Skrutskie, M. F.; Nelson, M. J.; Borish, H. J.; Kirkpatrick, J. Davy; Gelino, Christopher R.; Griffith, Roger L.; Jarrett, Tom; Marsh, Kenneth A.; Mainzer, Amanda K.; Eisenhardt, Peter R.; Tobin, John J.; Cushing, Michael C.

    2013-01-01

    The Wide-field Infrared Survey Explorer has revealed a T8.5 brown dwarf (WISE J111838.70+312537.9) that exhibits common proper motion with a solar-neighborhood (8 pc) quadruple star system—ξ Ursae Majoris. The angular separation is 8.'5, and the projected physical separation is ≈4000 AU. The sub-solar metallicity and low chromospheric activity of ξ UMa A argue that the system has an age of at least 2 Gyr. The infrared luminosity and color of the brown dwarf suggests the mass of this companion ranges between 14 and 38 M J for system ages of 2 and 8 Gyr, respectively.

  10. Alternative Specifications for the Lévy Libor Market Model: An Empirical Investigation

    DEFF Research Database (Denmark)

    Skovmand, David; Nicolato, Elisa

    This paper introduces and analyzes specications of the Lévy Market Model originally proposed by Eberlein and Özkan (2005). An investigation of the term structure of option implied moments rules out the Brownian motion and homogeneous Lévy processes as suitable modeling devices, and consequently a...

  11. The Mitochondrial Genome of Toxocara canis

    OpenAIRE

    Jex, Aaron R.; Waeschenbach, Andrea; Littlewood, D. Timothy J.; Hu, Min; Gasser, Robin B.

    2008-01-01

    Toxocara canis (Ascaridida: Nematoda), which parasitizes (at the adult stage) the small intestine of canids, can be transmitted to a range of other mammals, including humans, and can cause the disease toxocariasis. Despite its significance as a pathogen, the genetics, epidemiology and biology of this parasite remain poorly understood. In addition, the zoonotic potential of related species of Toxocara, such as T. cati and T. malaysiensis, is not well known. Mitochondrial DNA is known to provid...

  12. Canine vector-borne co-infections: Ehrlichia canis and Hepatozoon canis in the same host monocytes.

    Science.gov (United States)

    Baneth, Gad; Harrus, Shimon; Gal, Arnon; Aroch, Itamar

    2015-02-28

    The protozoon Hepatozoon canis and the rickettsia Ehrlichia canis are tick-borne pathogens, transmitted by Rhipicephalus sanguineus, which cause canine hepatozoonosis and canine monocytic ehrlichiosis, respectively. Co-infection of the same host monocytes with H. canis and E. canis confirmed by molecular characterization of the infecting agents and quantitative assessment of co-infected cells is described for the first time in three naturally-infected dogs. Blood smear evaluation indicated that at least 50% of the leukocytes infected with H. canis gamonts contained E. canis morulae. Co-infection of the same host cell demonstrated in this report suggests that infection with one pathogen may permit or enhance invasion or prolonged cellular survival of the other. Copyright © 2014 Elsevier B.V. All rights reserved.

  13. Different Babesia canis isolates, different diseases.

    Science.gov (United States)

    Schetters, T P; Moubri, K; Précigout, E; Kleuskens, J; Scholtes, N C; Gorenflot, A

    1997-11-01

    Using surface immunofluorescence isolate-specific antigens were detected on the membrane of erythrocytes infected with Babesia parasites. In addition, the strains reacted differently with Plasmagel in that the European isolate (B.c. canis) could be purified on Plasmagel effectively, whereas infected erythrocytes of the South-African isolate (B.c. rossi) could not. Experimental infection of dogs with Babesia canis isolates from geographically different areas revealed different pathology. The European isolate obtained from France exhibited transient parasitaemia, usually below 1%, associated with low PCV values and congestion of internal organs. Clinical disease was correlated with an effect on the coagulation system, and not with peripheral parasitaemia. Infection of dogs with South-African-derived isolate induced high parasitaemia usually much higher than 1%, which required chemotherapeutic treatment. In these animals clinical disease was correlated with peripheral parasitaemia and not with parameters of the coagulation system. The results show that the etiology of disease caused by these isolates of B.c. canis and B.c. rossi is different. This might have implications for the development of vaccines against these infections.

  14. Quantity discrimination in wolves (Canis lupus

    Directory of Open Access Journals (Sweden)

    Ewelina eUtrata

    2012-11-01

    Full Text Available Quantity discrimination has been studied extensively in different non-human animal species. In the current study, we tested eleven hand-raised wolves (Canis lupus in a two-way choice task. We placed a number of food items (one to four sequentially into two opaque cans and asked the wolves to choose the larger amount. Moreover, we conducted two additional control conditions to rule out non-numerical properties of the presentation that the animals might have used to make the correct choice. Our results showed that wolves are able to make quantitative judgments at the group, but also at the individual level even when alternative strategies such as paying attention to the surface area or time and total amount are ruled out. In contrast to previous canine studies on dogs (Canis familiaris and coyotes (Canis latrans, our wolves’ performance did not improve with decreasing ratio, referred to as Weber’s law. However, further studies using larger quantities than we used in the current setup are still needed to determine whether and when wolves’ quantity discrimination conforms to Weber’s law.

  15. Development of multiplex polymerase chain reaction for detection of Ehrlichia canis, Babesia spp and Hepatozoon canis in canine blood.

    Science.gov (United States)

    Kledmanee, Kan; Suwanpakdee, Sarin; Krajangwong, Sakranmanee; Chatsiriwech, Jarin; Suksai, Parut; Suwannachat, Pongpun; Sariya, Ladawan; Buddhirongawatr, Ruangrat; Charoonrut, Phingphol; Chaichoun, Kridsada

    2009-01-01

    A multiplex polymerase chain reaction (PCR) has been developed for simultaneous detection of canine blood parasites, Ehrlichia canis, Babesia spp and Hepatozoon canis, from blood samples in a single reaction. The multiplex PCR primers were specific to E. canis VirB9, Babesia spp 16S rRNA and H. canis 16S rRNA genes. Specificity of the amplicons was confirmed by DNA sequencing. The assay was evaluated using normal canine and infected blood samples, which were detected by microscopic examination. This multiplex PCR offers scope for simultaneous detection of three important canine blood parasites and should be valuable in monitoring parasite infections in dogs and ticks.

  16. vy night flights by the jellyfish Periphylla periphylla

    KAUST Repository

    Ugland, KI

    2014-10-22

    Jellyfish blooms occur in marine environments around the world and have been linked to over-fishing, eutrophication and climatic change. In some coastal areas of Norway, the circumglobal Periphylla periphylla has increased to exceptionally high abundances and has replaced fish as the main planktivorous predator despite the ineffectiveness of its non-visual predation compared to visual fish predation. Using data from a bottom-mounted acoustic platform, we collected 12341 in situ measurements of individual vertical movements of large individuals of P. periphylla. These jellyfish are characterized by a stepwise vertical movement. The distribution of their vertical swimming distances was extremely left skewed; about 85% of the swimming distances were less than 3 m, and a few displacements were extremely long with a maximum of 85 m. Chi-square tests of goodness of fit to the tail and Akaike’s information criterion gave overwhelming evidence of the truncated power law. There was a clear diel pattern in the exponent with values significantly larger than 3 during the daytime and significantly lower than 3 at night. This pattern means that P. periphylla switches from relatively limited movements during the day to Lévy-like flights during the night. Since the abundance of zooplankton is large in the P. periphylla fjord, Brownian motion, rather than Lévy flight, is predicted by the optimal foraging hypothesis. It is therefore possible that the Lévy-like search pattern has evolved in the food-scarce oceanic environment, which is the main natural habitat of P. periphylla. Alternatively, the large individuals of the population addressed here may forage on scarcer prey sources than the main prevailing zooplankton in Lurefjorden.

  17. vy-Student distributions for halos in accelerator beams.

    Science.gov (United States)

    Cufaro Petroni, Nicola; De Martino, Salvatore; De Siena, Silvio; Illuminati, Fabrizio

    2005-12-01

    We describe the transverse beam distribution in particle accelerators within the controlled, stochastic dynamical scheme of stochastic mechanics (SM) which produces time reversal invariant diffusion processes. This leads to a linearized theory summarized in a Schrödinger-like (SL) equation. The space charge effects have been introduced in recent papers by coupling this S-L equation with the Maxwell equations. We analyze the space-charge effects to understand how the dynamics produces the actual beam distributions, and in particular we show how the stationary, self-consistent solutions are related to the (external and space-charge) potentials both when we suppose that the external field is harmonic (constant focusing), and when we a priori prescribe the shape of the stationary solution. We then proceed to discuss a few other ideas by introducing generalized Student distributions, namely, non-Gaussian, Lévy infinitely divisible (but not stable) distributions. We will discuss this idea from two different standpoints: (a) first by supposing that the stationary distribution of our (Wiener powered) SM model is a Student distribution; (b) by supposing that our model is based on a (non-Gaussian) Lévy process whose increments are Student distributed. We show that in the case (a) the longer tails of the power decay of the Student laws and in the case (b) the discontinuities of the Lévy-Student process can well account for the rare escape of particles from the beam core, and hence for the formation of a halo in intense beams.

  18. vy night flights by the jellyfish Periphylla periphylla

    KAUST Repository

    Ugland, KI; Aksnes, DL; Klevjer, TA; Titelman, J; Kaartvedt, Stein

    2014-01-01

    Jellyfish blooms occur in marine environments around the world and have been linked to over-fishing, eutrophication and climatic change. In some coastal areas of Norway, the circumglobal Periphylla periphylla has increased to exceptionally high abundances and has replaced fish as the main planktivorous predator despite the ineffectiveness of its non-visual predation compared to visual fish predation. Using data from a bottom-mounted acoustic platform, we collected 12341 in situ measurements of individual vertical movements of large individuals of P. periphylla. These jellyfish are characterized by a stepwise vertical movement. The distribution of their vertical swimming distances was extremely left skewed; about 85% of the swimming distances were less than 3 m, and a few displacements were extremely long with a maximum of 85 m. Chi-square tests of goodness of fit to the tail and Akaike’s information criterion gave overwhelming evidence of the truncated power law. There was a clear diel pattern in the exponent with values significantly larger than 3 during the daytime and significantly lower than 3 at night. This pattern means that P. periphylla switches from relatively limited movements during the day to Lévy-like flights during the night. Since the abundance of zooplankton is large in the P. periphylla fjord, Brownian motion, rather than Lévy flight, is predicted by the optimal foraging hypothesis. It is therefore possible that the Lévy-like search pattern has evolved in the food-scarce oceanic environment, which is the main natural habitat of P. periphylla. Alternatively, the large individuals of the population addressed here may forage on scarcer prey sources than the main prevailing zooplankton in Lurefjorden.

  19. Prevalence of Ehrlichia canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, Bartonella vinsonii berkhoffii, and Rickettsia spp. in dogs from Grenada.

    Science.gov (United States)

    Yabsley, Michael J; McKibben, John; Macpherson, Calum N; Cattan, Peggy F; Cherry, Natalie A; Hegarty, Barbara C; Breitschwerdt, Edward B; O'Connor, Tom; Chandrashekar, Ramaswamy; Paterson, Tara; Perea, Marta Lanza; Ball, Geoffrey; Friesen, Stanley; Goedde, Jill; Henderson, Brooke; Sylvester, Wayne

    2008-02-14

    To identify the tick-borne pathogens in dogs from Grenada, we conducted a serologic survey for Ehrlichia canis in 2004 (104 dogs) and a comprehensive serologic and molecular survey for a variety of tick-borne pathogens in 2006 (73 dogs). In 2004 and 2006, 44 and 32 dogs (42.3% and 43.8%) were seropositive for E. canis, respectively. In 2006, several tick-borne pathogens were identified by serology and PCR. DNA of E. canis, Anaplasma platys, Babesia canis vogeli, Hepatozoon canis, and Bartonella sp. were identified in 18 (24.7%), 14 (19.2%), 5 (7%), 5 (7%), and 1 (1.4%) dogs, respectively. Six (8.2%) dogs were seropositive for Bartonella vinsonii subsp. berkhoffii. All dogs were seronegative and PCR-negative for Rickettsia spp. Coinfection with two or three pathogens was observed in eight dogs. Partial 16S rRNA E. canis and A. platys sequences were identical to sequences in GenBank. Partial 18S rRNA gene sequences from the Grenadian H. canis were identical to each other and had one possible mismatch (ambiguous base) from H. canis detected from Spain and Brazil. Grenadian B. c. vogeli sequences were identical to B. c. vogeli from Brazil and Japan. All of the detected pathogens are transmitted, or suspected to be transmitted, by Rhipicephalus sanguineus. Results of this study indicate that dogs from Grenada are infected with multiple tick-borne pathogens; therefore, tick-borne diseases should be included as differentials for dogs exhibiting thrombocytopenia, leukopenia, fever, or lethargy. One pathogen, E. canis, is also of potential public health significance.

  20. Experimental evidence against transmission of Hepatozoon canis by Ixodes ricinus.

    Science.gov (United States)

    Giannelli, Alessio; Ramos, Rafael Antonio Nascimento; Dantas-Torres, Filipe; Mencke, Norbert; Baneth, Gad; Otranto, Domenico

    2013-09-01

    Hepatozoon canis is among the most widespread tick-borne protozoa infecting domestic and wild carnivores. Its distribution is related to the occurrence of its major vector, the brown dog tick Rhipicephalus sanguineus. However, the role of Ixodes ricinus as a vector of H. canis has been hypothesized. In the present study, the development of H. canis was investigated in I. ricinus and R. sanguineus nymphs collected from a naturally infested dog. All I. ricinus ticks examined (n=133) were negative by cytological examination at days 20, 30, and 90 post collection, although H. canis DNA was detected in one nymph at day 20 and in 2 nymphs at day 30 post collection. On the other hand, H. canis sporogony was documented by cytology, and H. canis DNA was detected by PCR in R. sanguineus at day 30 post collection. These results indicate that H. canis sporogony does not occur in I. ricinus, but in R. sanguineus, suggesting that I. ricinus does not act as a vector of H. canis. Copyright © 2013 Elsevier GmbH. All rights reserved.

  1. Helicobacter canis bacteremia in a renal transplant patient

    NARCIS (Netherlands)

    van der Vusse, M. L.; van Son, W. J.; Ott, A.; Manson, W.

    Here we present a case report of a 41-year-old woman suffering from high fever and bacteremia due to Helicobacter canis, 11months after kidney transplantation. Identification of H.canis was achieved by 16s rDNA sequence analysis of a positive blood culture. The patient was restored fully to health

  2. Endocarditis caused by Streptococcus canis: an emerging zoonosis?

    Science.gov (United States)

    Lacave, Guillaume; Coutard, Aymeric; Troché, Gilles; Augusto, Sandrine; Pons, Stéphanie; Zuber, Benjamin; Laurent, Virginie; Amara, Marlène; Couzon, Brigitte; Bédos, Jean-Pierre; Pangon, Béatrice; Grimaldi, David

    2016-02-01

    We report a human case of infective endocarditis caused by Streptococcus canis. Identification was carried out from positive blood culture using mass spectrometry and SodA gene sequencing. S. canis related zoonotic invasive infections may have been previously underdiagnosed due to inadequate identification of group G Streptococcus species.

  3. vy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Science.gov (United States)

    Wu, Juan; Xu, Yong; Ma, Jun

    2017-01-01

    As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  4. vy noise improves the electrical activity in a neuron under electromagnetic radiation.

    Directory of Open Access Journals (Sweden)

    Juan Wu

    Full Text Available As the fluctuations of the internal bioelectricity of nervous system is various and complex, the external electromagnetic radiation induced by magnet flux on membrane can be described by the non-Gaussian type distribution of Lévy noise. Thus, the electrical activities in an improved Hindmarsh-Rose model excited by the external electromagnetic radiation of Lévy noise are investigated and some interesting modes of the electrical activities are exhibited. The external electromagnetic radiation of Lévy noise leads to the mode transition of the electrical activities and spatial phase, such as from the rest state to the firing state, from the spiking state to the spiking state with more spikes, and from the spiking state to the bursting state. Then the time points of the firing state versus Lévy noise intensity are depicted. The increasing of Lévy noise intensity heightens the neuron firing. Also the stationary probability distribution functions of the membrane potential of the neuron induced by the external electromagnetic radiation of Lévy noise with different intensity, stability index and skewness papremeters are analyzed. Moreover, through the positive largest Lyapunov exponent, the parameter regions of chaotic electrical mode of the neuron induced by the external electromagnetic radiation of Lévy noise distribution are detected.

  5. Rhipicephalus turanicus, a new vector of Hepatozoon canis.

    Science.gov (United States)

    Giannelli, Alessio; Lia, Riccardo Paolo; Annoscia, Giada; Buonavoglia, Canio; Lorusso, Eleonora; Dantas-Torres, Filipe; Baneth, Gad; Otranto, Domenico

    2017-05-01

    The distribution of Hepatozoon canis mainly encompasses areas where its main tick vector, Rhipicephalus sanguineus sensu lato, is present. However, the detection of this pathogen in dogs, foxes and golden jackals well outside the areas inhabited by this tick species reinforced the hypothesis that additional ixodids are involved in the life cycle and transmission of this protozoon. The present study provides, for the first time, data supporting the sporogonic development of H. canis in specimens of Rhipicephalus turanicus collected from a naturally infected fox from southern Italy. The epidemiological role of R. turanicus as a vector of H. canis is discussed, along with information on the potential use of cell cultures for the experimental infection with H. canis sporozoites. The in vitro infection of canine leucocytes by sporozoites from ticks is proposed as a potential tool for future in-depth studies on the biology of H. canis.

  6. CanisOme--The protein signatures of Canis lupus familiaris diseases.

    Science.gov (United States)

    Fernandes, Mónica; Rosa, Nuno; Esteves, Eduardo; Correia, Maria José; Arrais, Joel; Ribeiro, Paulo; Vala, Helena; Barros, Marlene

    2016-03-16

    Although the applications of Proteomics in Human Biomedicine have been explored for some time now, in animal and veterinary research, the potential of this resource has just started to be explored, especially when companion animal health is considered. In the last years, knowledge on the Canis lupus familiaris proteome has been accumulating in the literature and a resource compiling all this information and critically reviewing it was lacking. This article presents such a resource for the first time. CanisOme is a database of all proteins identified in Canis lupus familiaris tissues, either in health or in disease, annotated with information on the proteins present on the sample and on the donors. This database reunites information on 549 proteins, associated with 63 dog diseases and 33 dog breeds. Examples of how this information may be used to produce new hypothesis on disease mechanisms is presented both through the functional analysis of the proteins quantified in canine cutaneous mast cell tumors and through the study of the interactome of C. lupus familiaris and Leishmania infantum. Therefore, the usefulness of CanisOme for researchers looking for protein biomarkers in dogs and interested in a comprehensive analysis of disease mechanisms is demonstrated. This paper presents CanisOme, a database of proteomic studies with relevant protein annotation, allowing the enlightenment of disease mechanisms and the discovery of novel disease biomarkers for C. lupus familiaris. This knowledge is important not only for the improvement of animal health but also for the use of dogs as models for human health studies. Copyright © 2016 Elsevier B.V. All rights reserved.

  7. Stable Lévy motion with inverse Gaussian subordinator

    Science.gov (United States)

    Kumar, A.; Wyłomańska, A.; Gajda, J.

    2017-09-01

    In this paper we study the stable Lévy motion subordinated by the so-called inverse Gaussian process. This process extends the well known normal inverse Gaussian (NIG) process introduced by Barndorff-Nielsen, which arises by subordinating ordinary Brownian motion (with drift) with inverse Gaussian process. The NIG process found many interesting applications, especially in financial data description. We discuss here the main features of the introduced subordinated process, such as distributional properties, existence of fractional order moments and asymptotic tail behavior. We show the connection of the process with continuous time random walk. Further, the governing fractional partial differential equations for the probability density function is also obtained. Moreover, we discuss the asymptotic distribution of sample mean square displacement, the main tool in detection of anomalous diffusion phenomena (Metzler et al., 2014). In order to apply the stable Lévy motion time-changed by inverse Gaussian subordinator we propose a step-by-step procedure of parameters estimation. At the end, we show how the examined process can be useful to model financial time series.

  8. Molecular confirmation of Hepatozoon canis in Mauritius.

    Science.gov (United States)

    Daskalaki, Aikaterini Alexandra; Ionică, Angela Monica; Jeetah, Keshav; Gherman, Călin Mircea; Mihalca, Andrei Daniel

    2018-01-01

    In this study, Hepatozoon species was molecularly identified and characterized for the first time on the Indian Ocean island of Mauritius. Partial sequences of the 18S rRNA gene of the Hepatozoon isolates were analysed from three naturally infected dogs. The sequences of H. canis were similar to the 18S rRNA partial sequences (JX112783, AB365071 99%) from dog blood samples from West Indies and Nigeria. Our sequences were deposited in the GenBank database. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Dynamics of two competing species in the presence of Lévy noise sources

    Science.gov (United States)

    La Cognata, A.; Valenti, D.; Dubkov, A. A.; Spagnolo, B.

    2010-07-01

    We consider a Lotka-Volterra system of two competing species subject to multiplicative α -stable Lévy noise. The interaction parameter between the species is a random process which obeys a stochastic differential equation with a generalized bistable potential in the presence both of a periodic driving term and an additive α -stable Lévy noise. We study the species dynamics, which is characterized by two different regimes, exclusion of one species and coexistence of both. We find quasiperiodic oscillations and stochastic resonance phenomenon in the dynamics of the competing species, analyzing the role of the Lévy noise sources.

  10. SDP_mharwit_1: Demonstration of HIFI Linear Polarization Analysis of Spectral Features

    Science.gov (United States)

    Harwit, M.

    2010-03-01

    We propose to observe the polarization of the 621 GHz water vapor maser in VY Canis Majoris to demonstrate the capability of HIFI to make polarization observations of Far-Infrared/Submillimeter spectral lines. The proposed Demonstration Phase would: - Show that HIFI is capable of interesting linear polarization measurements of spectral lines; - Test out the highest spectral resolving power to sort out closely spaced Doppler components; - Determine whether the relative intensities predicted by Neufeld and Melnick are correct; - Record the degree and direction of linear polarization for the closely-Doppler shifted peaks.

  11. An infrared upconverter for astronomical imaging

    Science.gov (United States)

    Boyd, R. W.; Townes, C. H.

    1977-01-01

    An imaging upconverter has been constructed which is suitable for use in the study of the thermal 10-micron radiation from astronomical sources. The infrared radiation is converted to visible radiation by mixing in a 1-cm-long proustite crystal. The phase-matched 2-kayser bandpass is tunable from 9 to 11 microns. The conversion efficiency is 2 by 10 to the -7th power and the field of view of 40 arc seconds on the sky contains several hundred picture elements, approximately diffraction-limited resolution in a large telescope. The instrument has been used in studies of the sun, moon, Mercury, and VY Canis Majoris.

  12. Molecular characterization of Hepatozoon canis from farm dogs in Pakistan.

    Science.gov (United States)

    Ahmad, Abdullah S; Saeed, Muhammad A; Rashid, Imran; Ashraf, Kamran; Shehzad, Wasim; Traub, Rebecca J; Baneth, Gad; Jabbar, Abdul

    2018-04-01

    Hepatozoon canis is a tick-borne pathogen of canids, which is distributed worldwide. However, very little is known about this protozoan parasite in Pakistan. This study provides the first molecular evidence of H. canis from farm dogs from three agro-ecological zones of Punjab, Pakistan. A conventional PCR targeting the 18S rRNA gene was used to characterize H. canis from farm dogs from three districts, namely Kasur, Rawalpindi, and Muzaffargarh, in Punjab. Of 341 blood samples tested, 155 (45.5%) were positive for H. canis, 73 (61.3%) from Kasur, 46 (42.5%) from Rawalpindi, and 36 (31.5%) from Muzaffargarh. Phylogenetic analyses revealed that 18S rRNA sequences of H. canis from this study clustered in three clades with those of H. canis from previously published studies to the exclusion of all other Hepatozoon spp. included in the analysis. This study provides the first insight into H. canis from farm dogs in Pakistan. Furthermore, it lays a foundation for future studies of the parasite to assess the impact of canine hepatozoonosis in dogs from various agro-ecological zones in Pakistan where pet ownership of dogs is increasing.

  13. Error analysis in Fourier methods for option pricing for exponential Lévy processes

    KAUST Repository

    Crocce, Fabian; Hä ppö lä , Juho; Keissling, Jonas; Tempone, Raul

    2015-01-01

    We derive an error bound for utilising the discrete Fourier transform method for solving Partial Integro-Differential Equations (PIDE) that describe european option prices for exponential Lévy driven asset prices. We give sufficient conditions

  14. Parisian ruin probability for spectrally negative L\\'{e}vy processes

    OpenAIRE

    Ronnie Loeffen; Irmina Czarna; Zbigniew Palmowski

    2011-01-01

    In this note we give, for a spectrally negative Lévy process, a compact formula for the Parisian ruin probability, which is defined by the probability that the process exhibits an excursion below zero, with a length that exceeds a certain fixed period $r$. The formula involves only the scale function of the spectrally negative Lévy process and the distribution of the process at time $r$.

  15. Kernel-Correlated Lévy Field Driven Forward Rate and Application to Derivative Pricing

    International Nuclear Information System (INIS)

    Bo Lijun; Wang Yongjin; Yang Xuewei

    2013-01-01

    We propose a term structure of forward rates driven by a kernel-correlated Lévy random field under the HJM framework. The kernel-correlated Lévy random field is composed of a kernel-correlated Gaussian random field and a centered Poisson random measure. We shall give a criterion to preclude arbitrage under the risk-neutral pricing measure. As applications, an interest rate derivative with general payoff functional is priced under this pricing measure

  16. Numerical Methods for the Lévy LIBOR Model

    DEFF Research Database (Denmark)

    Papapantoleon, Antonis; Skovmand, David

    are generally slow. We propose an alternative approximation scheme based on Picard iterations. Our approach is similar in accuracy to the full numerical solution, but with the feature that each rate is, unlike the standard method, evolved independently of the other rates in the term structure. This enables...... simultaneous calculation of derivative prices of different maturities using parallel computing. We include numerical illustrations of the accuracy and speed of our method pricing caplets.......The aim of this work is to provide fast and accurate approximation schemes for the Monte-Carlo pricing of derivatives in the Lévy LIBOR model of Eberlein and Özkan (2005). Standard methods can be applied to solve the stochastic differential equations of the successive LIBOR rates but the methods...

  17. Demodicosis caused by Demodex canis and Demodex cornei in dogs

    OpenAIRE

    Sivajothi, S.; Sudhakara Reddy, B.; Rayulu, V. C.

    2013-01-01

    Two mongrel dogs aged between 7 and 9 months in a same house were presented to the clinics with a history of chronic dermatitis associated with pruritus. Clinical examination revealed presence of primary and secondary skin lesions on the face, around the ears, chin, neck, fore limbs and lateral abdomen. Examination of skin scrapings revealed Demodex cornei (majority) and D. canis (minority) in both the dogs. By using hair pluck examination D. canis were detected and by tape impression smears ...

  18. Adaptive Lévy processes and area-restricted search in human foraging.

    Directory of Open Access Journals (Sweden)

    Thomas T Hills

    Full Text Available A considerable amount of research has claimed that animals' foraging behaviors display movement lengths with power-law distributed tails, characteristic of Lévy flights and Lévy walks. Though these claims have recently come into question, the proposal that many animals forage using Lévy processes nonetheless remains. A Lévy process does not consider when or where resources are encountered, and samples movement lengths independently of past experience. However, Lévy processes too have come into question based on the observation that in patchy resource environments resource-sensitive foraging strategies, like area-restricted search, perform better than Lévy flights yet can still generate heavy-tailed distributions of movement lengths. To investigate these questions further, we tracked humans as they searched for hidden resources in an open-field virtual environment, with either patchy or dispersed resource distributions. Supporting previous research, for both conditions logarithmic binning methods were consistent with Lévy flights and rank-frequency methods-comparing alternative distributions using maximum likelihood methods-showed the strongest support for bounded power-law distributions (truncated Lévy flights. However, goodness-of-fit tests found that even bounded power-law distributions only accurately characterized movement behavior for 4 (out of 32 participants. Moreover, paths in the patchy environment (but not the dispersed environment showed a transition to intensive search following resource encounters, characteristic of area-restricted search. Transferring paths between environments revealed that paths generated in the patchy environment were adapted to that environment. Our results suggest that though power-law distributions do not accurately reflect human search, Lévy processes may still describe movement in dispersed environments, but not in patchy environments-where search was area-restricted. Furthermore, our results

  19. Molecular detection of Hepatozoon canis and Babesia canis vogeli in domestic dogs from Cuiabá, Brazil.

    Science.gov (United States)

    Spolidorio, Mariana Granziera; Torres, Mariana de Medeiros; Campos, Wilma Neres da Silva; Melo, Andréia Lima Tomé; Igarashi, Michelle; Amude, Alexandre Mendes; Labruna, Marcelo Bahia; Aguiar, Daniel Moura

    2011-01-01

    The objective of this study was to report for the first time infection by Hepatozoon spp. and Babesia spp. in 10 dogs from the city of Cuiabá, State of Mato Grosso, central-western Brazil. A pair of primers that amplifies a 574 bp fragment of the 18S rRNA of Hepatozoon spp., and a pair of primers that amplifies a 551 bp fragment of the gene 18S rRNA for Babesia spp. were used. Six dogs were positive for Babesia spp., and 9 were positive for Hepatozoon spp. Co‑infection of Babesia spp. and Hepatozoon spp. was seen in 5 dogs. Sequenced samples revealed 100% identity with B. canis vogeli, and H. canis. This is the first molecular detection of H. canis in domestic dogs from Cuiabá. Additionally, it is described for the first time the presence of B. canis vogeli circulating among dogs in Cuiabá.

  20. Intrinsic Lévy behaviour in organisms - searching for a mechanism. Comment on "Liberating Lévy walk research from the shackles of optimal foraging" by A.M. Reynolds

    Science.gov (United States)

    Sims, David W.

    2015-09-01

    The seminal papers by Viswanathan and colleagues in the late 1990s [1,2] proposed not only that scale-free, superdiffusive Lévy walks can describe the free-ranging movement patterns observed in animals such as the albatross [1], but that the Lévy walk was optimal for searching for sparsely and randomly distributed resource targets [2]. This distinct advantage, now shown to be present over a much broader set of conditions than originally theorised [3], implied that the Lévy walk is a search strategy that should be found very widely in organisms [4]. In the years since there have been several influential empirical studies showing that Lévy walks can indeed be detected in the movement patterns of a very broad range of taxa, from jellyfish, insects, fish, reptiles, seabirds, humans [5-10], and even in the fossilised trails of extinct invertebrates [11]. The broad optimality and apparent deep evolutionary origin of movement (search) patterns that are well approximated by Lévy walks led to the development of the Lévy flight foraging (LFF) hypothesis [12], which states that "since Lévy flights and walks can optimize search efficiencies, therefore natural selection should have led to adaptations for Lévy flight foraging".

  1. Inferring Lévy walks from curved trajectories: A rescaling method

    Science.gov (United States)

    Tromer, R. M.; Barbosa, M. B.; Bartumeus, F.; Catalan, J.; da Luz, M. G. E.; Raposo, E. P.; Viswanathan, G. M.

    2015-08-01

    An important problem in the study of anomalous diffusion and transport concerns the proper analysis of trajectory data. The analysis and inference of Lévy walk patterns from empirical or simulated trajectories of particles in two and three-dimensional spaces (2D and 3D) is much more difficult than in 1D because path curvature is nonexistent in 1D but quite common in higher dimensions. Recently, a new method for detecting Lévy walks, which considers 1D projections of 2D or 3D trajectory data, has been proposed by Humphries et al. The key new idea is to exploit the fact that the 1D projection of a high-dimensional Lévy walk is itself a Lévy walk. Here, we ask whether or not this projection method is powerful enough to cleanly distinguish 2D Lévy walk with added curvature from a simple Markovian correlated random walk. We study the especially challenging case in which both 2D walks have exactly identical probability density functions (pdf) of step sizes as well as of turning angles between successive steps. Our approach extends the original projection method by introducing a rescaling of the projected data. Upon projection and coarse-graining, the renormalized pdf for the travel distances between successive turnings is seen to possess a fat tail when there is an underlying Lévy process. We exploit this effect to infer a Lévy walk process in the original high-dimensional curved trajectory. In contrast, no fat tail appears when a (Markovian) correlated random walk is analyzed in this way. We show that this procedure works extremely well in clearly identifying a Lévy walk even when there is noise from curvature. The present protocol may be useful in realistic contexts involving ongoing debates on the presence (or not) of Lévy walks related to animal movement on land (2D) and in air and oceans (3D).

  2. Signatures of active and passive optimized Lévy searching in jellyfish.

    Science.gov (United States)

    Reynolds, Andy M

    2014-10-06

    Some of the strongest empirical support for Lévy search theory has come from telemetry data for the dive patterns of marine predators (sharks, bony fishes, sea turtles and penguins). The dive patterns of the unusually large jellyfish Rhizostoma octopus do, however, sit outside of current Lévy search theory which predicts that a single search strategy is optimal. When searching the water column, the movement patterns of these jellyfish change over time. Movement bouts can be approximated by a variety of Lévy and Brownian (exponential) walks. The adaptive value of this variation is not known. On some occasions movement pattern data are consistent with the jellyfish prospecting away from a preferred depth, not finding an improvement in conditions elsewhere and so returning to their original depth. This 'bounce' behaviour also sits outside of current Lévy walk search theory. Here, it is shown that the jellyfish movement patterns are consistent with their using optimized 'fast simulated annealing'--a novel kind of Lévy walk search pattern--to locate the maximum prey concentration in the water column and/or to locate the strongest of many olfactory trails emanating from more distant prey. Fast simulated annealing is a powerful stochastic search algorithm for locating a global maximum that is hidden among many poorer local maxima in a large search space. This new finding shows that the notion of active optimized Lévy walk searching is not limited to the search for randomly and sparsely distributed resources, as previously thought, but can be extended to embrace other scenarios, including that of the jellyfish R. octopus. In the presence of convective currents, it could become energetically favourable to search the water column by riding the convective currents. Here, it is shown that these passive movements can be represented accurately by Lévy walks of the type occasionally seen in R. octopus. This result vividly illustrates that Lévy walks are not necessarily

  3. From Lévy to Brownian: a computational model based on biological fluctuation.

    Science.gov (United States)

    Nurzaman, Surya G; Matsumoto, Yoshio; Nakamura, Yutaka; Shirai, Kazumichi; Koizumi, Satoshi; Ishiguro, Hiroshi

    2011-02-03

    Theoretical studies predict that Lévy walks maximizes the chance of encountering randomly distributed targets with a low density, but Brownian walks is favorable inside a patch of targets with high density. Recently, experimental data reports that some animals indeed show a Lévy and Brownian walk movement patterns when forage for foods in areas with low and high density. This paper presents a simple, Gaussian-noise utilizing computational model that can realize such behavior. We extend Lévy walks model of one of the simplest creature, Escherichia coli, based on biological fluctuation framework. We build a simulation of a simple, generic animal to observe whether Lévy or Brownian walks will be performed properly depends on the target density, and investigate the emergent behavior in a commonly faced patchy environment where the density alternates. Based on the model, animal behavior of choosing Lévy or Brownian walk movement patterns based on the target density is able to be generated, without changing the essence of the stochastic property in Escherichia coli physiological mechanism as explained by related researches. The emergent behavior and its benefits in a patchy environment are also discussed. The model provides a framework for further investigation on the role of internal noise in realizing adaptive and efficient foraging behavior.

  4. Tail asymptotics for the supremum of an infinitely divisible field with convolution equivalent Lévy measure

    DEFF Research Database (Denmark)

    Rønn-Nielsen, Anders; Jensen, Eva B. Vedel

    We consider a continuous, infinitely divisible random field in Rd given as an integral of a kernel function with respect to a Lévy basis with convolution equivalent Lévy measure. For a large class of such random fields we compute the asymptotic probability that the supremum of the field exceeds...

  5. Aging in mortal superdiffusive Lévy walkers

    Science.gov (United States)

    Stage, Helena

    2017-12-01

    A growing body of literature examines the effects of superdiffusive subballistic movement premeasurement (aging or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these Lévy walkers, be they proteins, cells, or larger structures. We examine the effects of aging on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorized as arising from "natural" death or experimental artifacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate θ . This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales.

  6. Aging in mortal superdiffusive Lévy walkers.

    Science.gov (United States)

    Stage, Helena

    2017-12-01

    A growing body of literature examines the effects of superdiffusive subballistic movement premeasurement (aging or time lag) on observations arising from single-particle tracking. A neglected aspect is the finite lifetime of these Lévy walkers, be they proteins, cells, or larger structures. We examine the effects of aging on the motility of mortal walkers, and discuss the means by which permanent stopping of walkers may be categorized as arising from "natural" death or experimental artifacts such as low photostability or radiation damage. This is done by comparison of the walkers' mean squared displacement (MSD) with the front velocity of propagation of a group of walkers, which is found to be invariant under time lags. For any running time distribution of a mortal random walker, the MSD is tempered by the stopping rate θ. This provides a physical interpretation for truncated heavy-tailed diffusion processes and serves as a tool by which to better classify the underlying running time distributions of random walkers. Tempering of aged MSDs raises the issue of misinterpreting superdiffusive motion which appears Brownian or subdiffusive over certain time scales.

  7. Robert Lévy-Mandel (1923-2010)

    CERN Multimedia

    2010-01-01

    Former CERN Director Robert Lévy-Mandel passed away on 3 July at the age of 87.   After obtaining a diploma from the Institut polytechnique in Grenoble, in 1948 he started work at the CEA, and was involved in the development and construction of the Saclay institute's first particle accelerator, a Van de Graaff machine. From 1954 to 1957 he was responsible for the coordination, development and construction of the CEA’s Saturne synchrotron, which entered service in 1958. In 1963 he was appointed head of the Saturne Synchrotron Department. The team led the construction of the Gargamelle bubble chamber, which was installed at CERN, and made contributions to other major facilities, including the Big European Bubble Chamber (BEBC). In 1971 he was invited to come to Geneva by John Adams, who was in charge of the SPS accelerator project. With the start of the SPS project, CERN had two laboratories, one at Meyrin and one at Prévessin, each with its own Director General: ...

  8. Minimizing Banking Risk in a Lévy Process Setting

    Directory of Open Access Journals (Sweden)

    F. Gideon

    2007-01-01

    Full Text Available The primary functions of a bank are to obtain funds through deposits from external sources and to use the said funds to issue loans. Moreover, risk management practices related to the withdrawal of these bank deposits have always been of considerable interest. In this spirit, we construct Lévy process-driven models of banking reserves in order to address the problem of hedging deposit withdrawals from such institutions by means of reserves. Here reserves are related to outstanding debt and acts as a proxy for the assets held by the bank. The aforementioned modeling enables us to formulate a stochastic optimal control problem related to the minimization of reserve, depository, and intrinsic risk that are associated with the reserve process, the net cash flows from depository activity, and cumulative costs of the bank's provisioning strategy, respectively. A discussion of the main risk management issues arising from the optimization problem mentioned earlier forms an integral part of our paper. This includes the presentation of a numerical example involving a simulation of the provisions made for deposit withdrawals via treasuries and reserves.

  9. Optimal Foreign Exchange Rate Intervention in Lévy Markets

    Directory of Open Access Journals (Sweden)

    Masimba Aspinas Mutakaya

    2014-01-01

    Full Text Available This paper considers an exchange rate problem in Lévy markets, where the Central Bank has to intervene. We assume that, in the absence of control, the exchange rate evolves according to Brownian motion with a jump component. The Central Bank is allowed to intervene in order to keep the exchange rate as close as possible to a prespecified target value. The interventions by the Central Bank are associated with costs. We present the situation as an impulse control problem, where the objective of the bank is to minimize the intervention costs. In particular, the paper extends the model by Huang, 2009, to incorporate a jump component. We formulate and prove an optimal verification theorem for the impulse control. We then propose an impulse control and construct a value function and then verify that they solve the quasivariational inequalities. Our results suggest that if the expected number of jumps is high the Central Bank will intervene more frequently and with large intervention amounts hence the intervention costs will be high.

  10. Trophic cascades linking wolves (Canis lupus), coyotes (Canis latrans), and small mammals

    Science.gov (United States)

    Miller, B.J.; Harlow, H.J.; Harlow, T.S.; Biggins, D.; Ripple, W.J.

    2012-01-01

    When large carnivores are extirpated from ecosystems that evolved with apex predators, these systems can change at the herbivore and plant trophic levels. Such changes across trophic levels are called cascading effects and they are very important to conservation. Studies on the effects of reintroduced wolves in Yellowstone National Park have examined the interaction pathway of wolves (Canis lupus L., 1758) to ungulates to plants. This study examines the interaction effects of wolves to coyotes to rodents (reversing mesopredator release in the absence of wolves). Coyotes (Canis latrans Say, 1823) generally avoided areas near a wolf den. However, when in the proximity of a den, they used woody habitats (pine or sage) compared with herbaceous habitats (grass or forb or sedge)- when they were away from the wolf den. Our data suggested a significant increase in rodent numbers, particularly voles (genus Microtus Schrank, 1798), during the 3-year study on plots that were within 3 km of the wolf den, but we did not detect a significant change in rodent numbers over time for more distant plots. Predation by coyotes may have depressed numbers of small mammals in areas away from the wolf den. These factors indicate a top-down effect by wolves on coyotes and subsequently on the rodents of the area. Restoration of wolves could be a powerful tool for regulating predation at lower trophic levels.

  11. Angiostrongylus vasorum in 20 cani della provincia di Chieti, Italia

    Directory of Open Access Journals (Sweden)

    Daniela Morelli

    2011-01-01

    Full Text Available A seguito di un caso di Angiostrongylus vasorum, diagnosticato all’inizio del 2008 nella provincia di Chieti, è stata organizzata una ricerca parassitologica al fine di indagare la presenza del parassita nei cani nella stessa area. Da gennaio a settembre 2008 sono stati esaminati 178 cani, 56 carcasse e 122 campioni di feci. Nelle carcasse sono stati ricercati i parassiti adulti nel ventricolo destro e nell’arteria polmonare e le forme larvali in tessuti di organi interni e cervello. Nelle feci è stata ricercata la forma larvale L1 con tre metodiche diagnostiche utilizzate correntemente per la ricerca di endoparassiti e larve di strongili broncopolmonari. Sono stati diagnosticati 20 casi (8,9% con identificazione di parassiti adulti in 5 cani e larve L1 in altri 15 soggetti. L’esame anatomopatologico delle carcasse dei cani con nematodi adulti ha evidenziato polmonite, pleurite, schiuma rossastra in trachea, versamento di liquido sieroemorragico in cavità toracica e ingrossamento di linfonodi medinici e meseraici. L’esame istologico dei tessuti ha evidenziato quadri gravi e sovrapponibili con lesioni da localizzazione dei parassiti in reni, linfonodi e cervello. Il numero cospicuo di casi riscontrati ha reso indispensabile considerare l’angiostrongilosi nelle diagnosi differenziali degli esami clinici e autoptici di cani della provincia di Chieti (Italia e dei territori confinanti.

  12. Non-Gaussian distributions of melodic intervals in music: The Lévy-stable approximation

    Science.gov (United States)

    Niklasson, Gunnar A.; Niklasson, Maria H.

    2015-11-01

    The analysis of structural patterns in music is of interest in order to increase our fundamental understanding of music, as well as for devising algorithms for computer-generated music, so called algorithmic composition. Musical melodies can be analyzed in terms of a “music walk” between the pitches of successive tones in a notescript, in analogy with the “random walk” model commonly used in physics. We find that the distribution of melodic intervals between tones can be approximated with a Lévy-stable distribution. Since music also exibits self-affine scaling, we propose that the “music walk” should be modelled as a Lévy motion. We find that the Lévy motion model captures basic structural patterns in classical as well as in folk music.

  13. A non-Lévy random walk in chacma baboons: what does it mean?

    Directory of Open Access Journals (Sweden)

    Cédric Sueur

    Full Text Available The Lévy walk is found from amoebas to humans and has been described as the optimal strategy for food research. Recent results, however, have generated controversy about this conclusion since animals also display alternatives to the Lévy walk such as the Brownian walk or mental maps and because movement patterns found in some species only seem to depend on food patches distribution. Here I show that movement patterns of chacma baboons do not follow a Lévy walk but a Brownian process. Moreover this Brownian walk is not the main process responsible for movement patterns of baboons. Findings about their speed and trajectories show that baboons use metal maps and memory to find resources. Thus the Brownian process found in this species appears to be more dependent on the environment or might be an alternative when known food patches are depleted and when animals have to find new resources.

  14. Autocorrelation as a source of truncated Lévy flights in foreign exchange rates

    Science.gov (United States)

    Figueiredo, Annibal; Gleria, Iram; Matsushita, Raul; Da Silva, Sergio

    2003-05-01

    We suggest that the ultraslow speed of convergence associated with truncated Lévy flights (Phys. Rev. Lett. 73 (1994) 2946) may well be explained by autocorrelations in data. We show how a particular type of autocorrelation generates power laws consistent with a truncated Lévy flight. Stock exchanges have been suggested to be modeled by a truncated Lévy flight (Nature 376 (1995) 46; Physica A 297 (2001) 509; Econom. Bull. 7 (2002) 1). Here foreign exchange rate data are taken instead. Scaling power laws in the “probability of return to the origin” are shown to emerge for most currencies. A novel approach to measure how distant a process is from a Gaussian regime is presented.

  15. Emergence of Lévy Walks from Second-Order Stochastic Optimization

    Science.gov (United States)

    Kuśmierz, Łukasz; Toyoizumi, Taro

    2017-12-01

    In natural foraging, many organisms seem to perform two different types of motile search: directed search (taxis) and random search. The former is observed when the environment provides cues to guide motion towards a target. The latter involves no apparent memory or information processing and can be mathematically modeled by random walks. We show that both types of search can be generated by a common mechanism in which Lévy flights or Lévy walks emerge from a second-order gradient-based search with noisy observations. No explicit switching mechanism is required—instead, continuous transitions between the directed and random motions emerge depending on the Hessian matrix of the cost function. For a wide range of scenarios, the Lévy tail index is α =1 , consistent with previous observations in foraging organisms. These results suggest that adopting a second-order optimization method can be a useful strategy to combine efficient features of directed and random search.

  16. Sarcocystis canis associated hepatitis in a Steller sea lion (Eumetopias jubatus) from Alaska.

    Science.gov (United States)

    Welsh, Trista; Burek-Huntington, Kathy; Savage, Kate; Rosenthal, Benjamin; Dubey, J P

    2014-04-01

    Sarcocystis canis infection was associated with hepatitis in a Steller sea lion (Eumetopias jubatus). Intrahepatocellular protozoal schizonts were among areas of necrosis and inflammation. The parasite was genetically identical to S. canis and is the first report in a Steller sea lion, indicating another intermediate host species for S. canis.

  17. Isolation of viable neospora caninum from brains of wild gray wolves (canis lupus)

    Science.gov (United States)

    Neospora caninum is a common cause of abortion in cattle worldwide. Canids, including the dog and the dingo (Canis familiaris), the coyote (Canis latrans), and the gray wolf (Canis lupus) are its definitive hosts, but also can act as intermediate hosts by harbor tissue stages of the parasite that ca...

  18. Human stick balancing: Tuning Lèvy flights to improve balance control

    Science.gov (United States)

    Cabrera, Juan Luis; Milton, John G.

    2004-09-01

    State-dependent, or parametric, noise is an essential component of the neural control mechanism for stick balancing at the fingertip. High-speed motion analysis in three dimensions demonstrates that the controlling movements made by the fingertip during stick balancing can be described by a Lévy flight. The Lévy index, α, is approximately 0.9; a value close to optimal for a random search. With increased skill, the index α does not change. However, the tails of the Lévy distribution become broader. These observations suggest a Lévy flight that is truncated by the properties of the nervous and musculoskeletal system; the truncation decreasing as skill level increases. Measurements of the cross-correlation between the position of the tip of the stick and the fingertip demonstrate that the role of closed-loop feedback changes with increased skill. Moreover, estimation of the neural latencies for stick balancing show that for a given stick length, the latency increases with skill level. It is suggested that the neural control for stick balancing involves a mechanism in which brief intervals of consciously generated, corrective movements alternate with longer intervals of prediction-free control. With learning the truncation of the Lévy flight becomes better optimized for balance control and hence the time between successive conscious corrections increases. These observations provide the first evidence that changes in a Lévy flight may have functional significance for the nervous system. This work has implications for the control of balancing problems ranging from falling in the elderly to the design of two-legged robots and earthquake proof buildings.

  19. European Option Pricing with Transaction Costs in Lévy Jump Environment

    Directory of Open Access Journals (Sweden)

    Jiayin Li

    2014-01-01

    Full Text Available The European option pricing problem with transaction costs is investigated for a risky asset price model with Lévy jump. By the aid of arbitrage pricing theory and the generalized Itô formula (which includes Poisson jump, the explicit solution to the risk asset price model is given. According to arbitrage-free principle, we first discretize the continuous-time model. Then, in each small time interval, the transaction costs are introduced. By using the Δ-hedging strategy, the explicit solutions of the European options pricing formula with transaction costs are given for the risky asset price model with Lévy jump.

  20. A Stroock formula for a certain class of Lévy processes and applications to finance

    Directory of Open Access Journals (Sweden)

    M. Eddahbi

    2005-01-01

    Full Text Available We find a Stroock formula in the setting of generalized chaos expansion introduced by Nualart and Schoutens for a certain class of Lévy processes, using a Malliavin-type derivative based on the chaotic approach. As applications, we get the chaotic decomposition of the local time of a simple Lévy process as well as the chaotic expansion of the price of a financial asset and of the price of a European call option. We also study the behavior of the tracking error in the discrete delta neutral hedging under both the equivalent martingale measure and the historical probability.

  1. Cutaneous Hepatozoon canis infection in a dog from New Jersey.

    Science.gov (United States)

    Little, Liz; Baneth, Gad

    2011-05-01

    A 7-month-old mixed-breed intact female dog was presented to a private veterinarian with a 2 cm in diameter raised, pruritic, alopecic, subcutaneous, fluctuant swelling over the right eye. Cytology of the mass revealed many degenerate neutrophils, moderate numbers of eosinophils, moderate numbers of macrophages, rare mast cells, and few erythrocytes. Rare neutrophils contained a protozoal agent compatible with a Hepatozoon gamont. Real-time polymerase chain reaction of peripheral blood was positive for Hepatozoon canis. The complete sequence identity of the amplified 18S ribosomal RNA fragment from the dog's blood confirmed H. canis and proved it was relatively distant from the corresponding fragment sequence of Hepatozoon americanum. This case is important in documenting an unusual presentation of infection with H. canis outside of the southern United States. © 2011 The Author(s)

  2. Mycoplasma canis and urogenital disease in dogs in Norway

    DEFF Research Database (Denmark)

    L'Abee-Lund, T.M.; Heiene, R.; Friis, N.F.

    2003-01-01

    Mycoplasmas identified as Mycoplasma canis were isolated from nine dogs with clinical signs of urogenital disease in Norway over a period of 20 months. Some of the dogs had been treated unsuccessfully with antibiotics, and three were euthanased as a result of severe persistent disease. Seven...... of the dogs had a urinary tract infection, one had chronic purulent epididymitis and one had chronic prostatitis. Overt haematuria was frequently observed among the dogs with cystitis. M canis was isolated in pure culture from seven of the dogs and in mixed culture from the other two. In three cases...... the mycoplasma was cultivated only from urinary sediment, and it was typically obtained in smaller numbers than would be considered indicative of a urinary tract infection. In contrast with most mycoplasmas, the M canis isolated from all the dogs grew on ordinary blood agar plates used for routine...

  3. Book review, Amati cani, José Jorge Letria

    Directory of Open Access Journals (Sweden)

    Manuel Graziani

    2008-03-01

    Full Text Available Con Amati cani ci discostiamo per una volta dalle pubblicazioni a carattere scientifico, per dare il giusto risalto ad un’interessante raccolta di narrativa che esplora il rapporto tra l'uomo e il suo miglior amico. José Jorge Latria, noto soprattutto per essere un esponente di spicco della canzone politica portoghese e per le sue opere poetiche, teatrali e di letteratura per ragazzi, nello scrivere questo libro compie un vero e proprio atto d’amore verso i cani, con il preciso intento di costringere i lettori ad eliminare dal proprio vocabolario il gratuito modo di dire ‘mondo cane’. L’Autore delinea brevi ritratti di cani che, da Argo in poi, hanno accompagnato da amici veri i loro celebri padroni nella buona e nella cattiva sorte: racconta cioè la storia di quei cani che non sono sprofondati nella voragine dell’oblio perchè i loro padroni hanno raggiunto la celebrità nel mondo della letteratura, della politica, del cinema, delle scienze o della musica. Con a fianco un amico fedele come un cane, la vita ha avuto un sapore diverso per Ernest Hemingway, Isaac Newton, Sigmund Freud, Buster Keaton, Marilyn Monroe, Pablo Picasso, John Steinbeck, Lord Byron, Tim Burton e altri ancora, tutti personaggi che sono presenti in questo libro grazie ai cani che hanno condiviso con loro la vita e le memorie. La lettura di Amati cani dà piacere poichè in ognuno di questi racconti batte, affettuoso e delicato, il cuore di un cane; ma dà anche un pò da pensare in quanto celebra in maniera molto tenera l’amore, la fedeltà e la solidarietà tra l’uomo e il suo speciale amico a quattro zampe.

  4. A PCR-based epidemiological survey of Hepatozoon canis in dogs in Nigeria.

    Science.gov (United States)

    Sasaki, Mizuki; Omobowale, Olutayo; Ohta, Kaisaku; Tozuka, Morito; Matsuu, Aya; Hirata, Haruyuki; Nottidge, Helen Oyebukola; Ikadai, Hiromi; Oyamada, Takashi

    2008-07-01

    The prevalence of Hepatozoon canis infections in dogs in Nigeria was surveyed using molecular methods. DNA was extracted from blood samples obtained from 400 dogs. A primer set that amplified the Babesia canis 18S rRNA gene, which has high similarity to the H. canis 18S rRNA gene, was used for the PCR. As a result, samples from 81 dogs (20.3%) produced 757 bp bands, which differed from the 698 bp band that corresponded to B. canis infection. The sequence of the PCR products of 10 samples were determined, all of which corresponded with the H. canis sequence.

  5. vy meets poisson: a statistical artifact may lead to erroneous recategorization of Lévy walk as Brownian motion.

    Science.gov (United States)

    Gautestad, Arild O

    2013-03-01

    The flow of GPS data on animal space is challenging old paradigms, such as the issue of the scale-free Lévy walk versus scale-specific Brownian motion. Since these movement classes often require different protocols with respect to ecological analyses, further theoretical development in this field is important. I describe central concepts such as scale-specific versus scale-free movement and the difference between mechanistic and statistical-mechanical levels of analysis. Next, I report how a specific sampling scheme may have produced much confusion: a Lévy walk may be wrongly categorized as Brownian motion if the duration of a move, or bout, is used as a proxy for step length and a move is subjectively defined. Hence, the categorization and recategorization of movement class compliance surrounding the Lévy walk controversy may have been based on a statistical artifact. This issue may be avoided by collecting relocations at a fixed rate at a temporal scale that minimizes over- and undersampling.

  6. Stochastic resonance in underdamped periodic potential systems with alpha stable Lévy noise

    Science.gov (United States)

    Liu, Ruo-Nan; Kang, Yan-Mei

    2018-06-01

    In this paper, we investigate the effect of alpha stable Lévy noise with alpha stability index α (0 noise (0 noise has a more notable impact on the resonant effect of the asymmetric ratchet potential than that of the symmetric sinusoidal potential because of symmetry breaking.

  7. vy stable noise-induced transitions: stochastic resonance, resonant activation and dynamic hysteresis

    International Nuclear Information System (INIS)

    Dybiec, Bartłomiej; Gudowska-Nowak, Ewa

    2009-01-01

    A standard approach to analysis of noise-induced effects in stochastic dynamics assumes a Gaussian character of the noise term describing interaction of the analyzed system with its complex surroundings. An additional assumption about the existence of timescale separation between the dynamics of the measured observable and the typical timescale of the noise allows external fluctuations to be modeled as temporally uncorrelated and therefore white. However, in many natural phenomena the assumptions concerning the above mentioned properties of 'Gaussianity' and 'whiteness' of the noise can be violated. In this context, in contrast to the spatiotemporal coupling characterizing general forms of non-Markovian or semi-Markovian Lévy walks, so called Lévy flights correspond to the class of Markov processes which can still be interpreted as white, but distributed according to a more general, infinitely divisible, stable and non-Gaussian law. Lévy noise-driven non-equilibrium systems are known to manifest interesting physical properties and have been addressed in various scenarios of physical transport exhibiting a superdiffusive behavior. Here we present a brief overview of our recent investigations aimed at understanding features of stochastic dynamics under the influence of Lévy white noise perturbations. We find that the archetypal phenomena of noise-induced ordering are robust and can be detected also in systems driven by memoryless, non-Gaussian, heavy-tailed fluctuations with infinite variance

  8. Experimental evidence for inherent Lévy search behaviour in foraging animals.

    Science.gov (United States)

    Kölzsch, Andrea; Alzate, Adriana; Bartumeus, Frederic; de Jager, Monique; Weerman, Ellen J; Hengeveld, Geerten M; Naguib, Marc; Nolet, Bart A; van de Koppel, Johan

    2015-05-22

    Recently, Lévy walks have been put forward as a new paradigm for animal search and many cases have been made for its presence in nature. However, it remains debated whether Lévy walks are an inherent behavioural strategy or emerge from the animal reacting to its habitat. Here, we demonstrate signatures of Lévy behaviour in the search movement of mud snails (Hydrobia ulvae) based on a novel, direct assessment of movement properties in an experimental set-up using different food distributions. Our experimental data uncovered clusters of small movement steps alternating with long moves independent of food encounter and landscape complexity. Moreover, size distributions of these clusters followed truncated power laws. These two findings are characteristic signatures of mechanisms underlying inherent Lévy-like movement. Thus, our study provides clear experimental evidence that such multi-scale movement is an inherent behaviour rather than resulting from the animal interacting with its environment. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  9. On Lévy-driven vacation models with correlated busy periods and service interruptions

    NARCIS (Netherlands)

    Kella, O.; Boxma, O.; Mandjes, M.

    2010-01-01

    This paper considers queues with server vacations, but departs from the traditional setting in two ways: (i) the queueing model is driven by Lévy processes rather than just compound Poisson processes; (ii) the vacation lengths depend on the length of the server’s preceding busy period. Regarding the

  10. On the correlation structure of a Lévy-driven queue

    NARCIS (Netherlands)

    A. Es-Saghouani; M.R.H. Mandjes (Michel)

    2007-01-01

    textabstractIn this paper we consider a single-server queue with Lévy input, and in particular its workload process (Q(t)), for t > 0, with a focus on the correlation structure. With the correlation function defined as r(t) := Cov(Q(0),Q(t))/Var Q(0) (assuming that the workload process is in

  11. Bilateral V-Y flap for a perianal basal cell carcinoma: A case report

    Directory of Open Access Journals (Sweden)

    José P. Rivera-Chavarría

    2016-01-01

    Conclusion: Treatment modalities include early wide local excision to clear margins, ensuring further local recurrence and distant metastasis. The use of local V-Y advancement fasciocutaneous flaps may be another valid option for the reconstruction of perianal skin defects, with less morbidity than other flaps described in the literature.

  12. vy-noise-induced transport in a rough triple-well potential.

    Science.gov (United States)

    Li, Yongge; Xu, Yong; Kurths, Jürgen; Yue, Xiaole

    2016-10-01

    Rough energy landscape and noisy environment are two common features in many subjects, such as protein folding. Due to the wide findings of bursting or spiking phenomenon in biology science, small diffusions mixing large jumps are adopted to model the noisy environment that can be properly described by Lévy noise. We combine the Lévy noise with the rough energy landscape, modeled by a potential function superimposed by a fast oscillating function, and study the transport of a particle in a rough triple-well potential excited by Lévy noise, rather than only small perturbations. The probabilities of a particle staying in the middle well are considered under different amplitudes of roughness to find out how roughness affects the steady-state probability density function. Variations in the mean first passage time from the middle well to the right well have been investigated with respect to Lévy parameters and amplitudes of the roughness. In addition, we have examined the influences of roughness on the splitting probabilities of the first escape from the middle well. We uncover that the roughness can enhance significantly the first escape of a particle from the middle well, especially for different skewness parameters, but weak differences are found for stability index and noise intensity on the probabilities a particle staying in the middle well and splitting probability to the right.

  13. Simulation-based computation of the workload correlation function in a Lévy-driven queue

    NARCIS (Netherlands)

    Glynn, P.W.; Mandjes, M.

    2011-01-01

    In this paper we consider a single-server queue with Lévy input, and, in particular, its workload process (Qt)t≥0, focusing on its correlation structure. With the correlation function defined as r(t):= cov(Q0, Qt) / varQ0 (assuming that the workload process is in stationarity at time 0), we first

  14. Feller processes: the next generation in modeling. Brownian motion, Lévy processes and beyond.

    Directory of Open Access Journals (Sweden)

    Björn Böttcher

    Full Text Available We present a simple construction method for Feller processes and a framework for the generation of sample paths of Feller processes. The construction is based on state space dependent mixing of Lévy processes. Brownian Motion is one of the most frequently used continuous time Markov processes in applications. In recent years also Lévy processes, of which Brownian Motion is a special case, have become increasingly popular. Lévy processes are spatially homogeneous, but empirical data often suggest the use of spatially inhomogeneous processes. Thus it seems necessary to go to the next level of generalization: Feller processes. These include Lévy processes and in particular brownian motion as special cases but allow spatial inhomogeneities. Many properties of Feller processes are known, but proving the very existence is, in general, very technical. Moreover, an applicable framework for the generation of sample paths of a Feller process was missing. We explain, with practitioners in mind, how to overcome both of these obstacles. In particular our simulation technique allows to apply Monte Carlo methods to Feller processes.

  15. On critical cases in limit theory for stationary increments Lévy driven moving averages

    DEFF Research Database (Denmark)

    Basse-O'Connor, Andreas; Podolskij, Mark

    averages. The limit theory heavily depends on the interplay between the given order of the increments, the considered power, the Blumenthal-Getoor index of the driving pure jump Lévy process L and the behavior of the kernel function g at 0. In this work we will study the critical cases, which were...

  16. Esscher transforms and the minimal entropy martingale measure for exponential Lévy models

    DEFF Research Database (Denmark)

    Hubalek, Friedrich; Sgarra, C.

    In this paper we offer a systematic survey and comparison of the Esscher martingale transform for linear processes, the Esscher martingale transform for exponential processes, and the minimal entropy martingale measure for exponential lévy models and present some new results in order to give...

  17. Large deviation estimates for a Non-Markovian Lévy generator of big order

    International Nuclear Information System (INIS)

    Léandre, Rémi

    2015-01-01

    We give large deviation estimates for a non-markovian convolution semi-group with a non-local generator of Lévy type of big order and with the standard normalisation of semi-classical analysis. No stochastic process is associated to this semi-group. (paper)

  18. Transient analysis of one-sided Lévy-driven queues

    NARCIS (Netherlands)

    Starreveld, N.J.; Bekker, R.; Mandjes, M.

    2016-01-01

    In this article, we analyze the transient behavior of the workload process in a Lévy-driven queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of spectrally

  19. Transient analysis of one-sided Lévy-driven queues

    NARCIS (Netherlands)

    Starreveld, N.J.; R. Bekker (Rene); M.R.H. Mandjes (Michel)

    2016-01-01

    textabstractIn this article, we analyze the transient behavior of the workload process in a Lévy-driven queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of

  20. Transient analysis of one-sided Lévy-driven queues

    NARCIS (Netherlands)

    Starreveld, N.; Bekker, R.; Mandjes, M.R.H.

    2015-01-01

    In this paper we analyze the transient behavior of the workload process in a Lévy input queue. We are interested in the value of the workload process at a random epoch; this epoch is distributed as the sum of independent exponential random variables. We consider both cases of spectrally one-sided

  1. [Andreeva, E. and Belobrovtseva, I. "Tol'ko Vy poimete sleduiushchii tekst..."] / Avril Pyman

    Index Scriptorium Estoniae

    Pyman, Avril

    2014-01-01

    Arvustus: Andreeva, E. and Belobrovtseva, I. "Tol'ko Vy poimete sleduiushchii tekst...". Perepiska N. E. Andreeva i L. F. Zurova. Baltiiskii arkhiv: Russkaia kult'tura v Pribaltike, 13. Tallinna Ülikooli Slaavi Keelte ja Kultuuride Instituut, Tallinn, 2013

  2. A Lévy input fluid queue with input and workload regulation

    NARCIS (Netherlands)

    Palmowski, Z.B.; Vlasiou, M.; Zwart, B.

    2011-01-01

    We consider a queuing model with the workload evolving between consecutive i.i.d. exponential timers $\\{e_q^{(i)}\\}_{i=1,2,\\ldots}$ according to a spectrally positive Lévy process $Y_i(t)$ that is reflected at zero, and where the environment $i$ equals 0 or 1. When the exponential clock $e_q^{(i)}$

  3. Optimal Stopping Problems Driven by Lévy Processes and Pasting Principles

    NARCIS (Netherlands)

    Surya, B.A.

    2007-01-01

    Solving optimal stopping problems driven by Lévy processes has been a challenging task and has found many applications in modern theory of mathematical finance. For example situations in which optimal stopping typically arise include the problem of finding the arbitrage-free price of the American

  4. Hepatozoon canis infection in Slovakia: imported or autochthonous?

    Science.gov (United States)

    Majláthová, Viktória; Hurníková, Zuzana; Majláth, Igor; Petko, Branislav

    2007-01-01

    Tissue samples from nine red foxes (four samples of striated muscle tissue and five samples of heart tissue) that originated from the Michalovce district (Slovakia), an area with endemic occurrence of canine babesiosis were examined by PCR method using primers amplifying a fragment of the 18S rRNA spanning the V4 region of Babesia and Theileria. An unexpected determination of 450 bp DNA fragment of Hepatozoon canis was found in four samples. Partial sequences of the 18S rRNA gene from the H. canis showed 100% similarity with the sequence from Brasil isolate of H. canis from a pampas fox (Pseudalopex gymnocercus) (AY471615) as well as from a fox in Spain (AY150067) and from a dog in Brazil (AY864677). In the present study, we report the first PCR detection of Hepatozoon canis in a naturally infected red fox from Slovakia, a Rhipicephalus sanguineus-free region. We assume that the infection was spread by infected R. sanguineus that might have been brought to Slovakia by travelers, by golden jackals, or by foxes migrating because of expansion of golden jackals and environmental and climate changes.

  5. Infection of dogs with Babesia canis in Gwagwalada metropolis of ...

    African Journals Online (AJOL)

    Epidemiological investigation was carried out to determine the prevalence of infection with Babesia canis in dogs in Gwagwalada metropolis of the Federal Capital Territory, Abuja Nigeria, from November 2013 to January 2014. Blood samples were collected from 101 dogs and examined for the parasite. Data obtained were ...

  6. Serodetection of Ehrlichia canis amongst dogs in central Namibia

    Directory of Open Access Journals (Sweden)

    Rutendo Manyarara

    2015-06-01

    Full Text Available Ehrlichia canis is a major pathogen in dogs throughout Africa, yet it has not been reported in Namibia. The aim of this study was to determine the seroprevalence of canine ehrlichiosis in central Namibia using the ImmunoComb assay (Biogal, Galed Laboratories. The study included 76 dogs that presented to the Rhino Park Veterinary Clinic in the north-western suburb of Khomasdal, Windhoek, Namibia, as well as 30 stray dogs from the Windhoek branch of the Society for the Prevention of Cruelty to Animals. Of the 106 dogs tested, 53.8% were seropositive at titres > 1:80. Dogs that presented with symptoms of E. canis infection had a significantly higher seroprevalence (86.6% compared with apparently healthy dogs (41.6% (P = 0.00. Location of habitation was significant (P < 0.017, with a high percentage of dogs exposed to E. canis living in the northern or north-western part of Windhoek. As the first study to serologically establish E. canis as a major pathogen in dogs in central Namibia, it is notable that the highest proportion of seropositive dogs came from low-income areas. Further investigation is necessary to describe the ecology of this important tick-borne pathogen of companion animals in Namibia.

  7. Infection of dogs with Babesia canis in Gwagwalada metropolis of ...

    African Journals Online (AJOL)

    ADEYEYE

    2014-10-30

    Oct 30, 2014 ... determine the prevalence of Babesia canis and the correlation of infection with age, sex, breed, types of management and presence .... Table 3: Breed distribution of Babesia infection in dogs in Gwagwalada Area Council, FCT. Breed ... the management style of the dogs and infection with. Babesia. Table 5 ...

  8. MRI findings of spinal visceral larva migrans of Toxocara canis

    Energy Technology Data Exchange (ETDEWEB)

    Lee, In Ho, E-mail: leeinho1974@hanmail.ne [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of); Department of Radiology, Chungnam National University Hospital, 33 Munhwa-ro, Jung-gu, Daejeon 301-721 (Korea, Republic of); Kim, Sung Tae, E-mail: st7.kim@hotmail.co [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of); Oh, Dae Kun, E-mail: odk6464@nate.co [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of); Kim, Hyung-Jin, E-mail: hyungkim@skku.ed [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of); Kim, Keon Ha, E-mail: somatom@skku.ed [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of); Jeon, Pyoung, E-mail: drpjeon@gmail.co [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of); Byun, Hong Sik, E-mail: byun5474@skku.ed [Department of Radiology and Center for Imaging Science, Samsung Medical Center, Sungkyunkwan University School of Medicine, 50 Ilwon-dong, Gangnam-Gu, Seoul 135-710 (Korea, Republic of)

    2010-08-15

    Purpose: The purpose of this study is to investigate the MRI findings of visceral larva migrans (VLS) of Toxocara canis in spinal cord. Materials and methods: We retrospectively reviewed spinal MRI findings in eight patients with serologically proven Toxocara canis between 2005 and 2008. We evaluated the location, length, extent and migration of the lesion, MR signal intensity (SI), enhancement pattern, and swelling of the spinal cord. We evaluated clinical features including presenting symptoms and signs and treatment response. Results: Total 8 patients (M = 8; age range 36-79 years) were included. The lesions were located in the cervical or thoracic spinal cord in all patients. All lesions showed high SI and minimal or mild swelling of involved spinal cord on T2WI and focal nodular enhancement on posterior or posterolateral segment of spinal cord. The length of involved lesion was relatively short in most patients. There was a migration of lesion in one patient. In spite of albendazole or steroid treatment, neurological symptoms or signs were not significantly improved in all patients. Conclusion: Although all lesions show non-specific imaging findings like non-tumorous myelopathy mimicking transverse myelitis, single lesion, focal nodular enhancement on posterior or posterolateral segment of spinal cord, relatively short segmental involvement and migration of lesion may be characteristic findings of spinal VLM of Toxocara canis. In addition, the reluctant response to the treatment may be characteristic of spinal VLM of Toxocara canis.

  9. MRI findings of spinal visceral larva migrans of Toxocara canis

    International Nuclear Information System (INIS)

    Lee, In Ho; Kim, Sung Tae; Oh, Dae Kun; Kim, Hyung-Jin; Kim, Keon Ha; Jeon, Pyoung; Byun, Hong Sik

    2010-01-01

    Purpose: The purpose of this study is to investigate the MRI findings of visceral larva migrans (VLS) of Toxocara canis in spinal cord. Materials and methods: We retrospectively reviewed spinal MRI findings in eight patients with serologically proven Toxocara canis between 2005 and 2008. We evaluated the location, length, extent and migration of the lesion, MR signal intensity (SI), enhancement pattern, and swelling of the spinal cord. We evaluated clinical features including presenting symptoms and signs and treatment response. Results: Total 8 patients (M = 8; age range 36-79 years) were included. The lesions were located in the cervical or thoracic spinal cord in all patients. All lesions showed high SI and minimal or mild swelling of involved spinal cord on T2WI and focal nodular enhancement on posterior or posterolateral segment of spinal cord. The length of involved lesion was relatively short in most patients. There was a migration of lesion in one patient. In spite of albendazole or steroid treatment, neurological symptoms or signs were not significantly improved in all patients. Conclusion: Although all lesions show non-specific imaging findings like non-tumorous myelopathy mimicking transverse myelitis, single lesion, focal nodular enhancement on posterior or posterolateral segment of spinal cord, relatively short segmental involvement and migration of lesion may be characteristic findings of spinal VLM of Toxocara canis. In addition, the reluctant response to the treatment may be characteristic of spinal VLM of Toxocara canis.

  10. Investigation of tick vectors of Hepatozoon canis in Brazil.

    Science.gov (United States)

    Demoner, Larissa de Castro; Rubini, Adriano Stefani; Paduan, Karina dos Santos; Metzger, Betina; de Paula Antunes, João Marcelo Azevedo; Martins, Thiago Fenandes; Mathias, Maria Izabel Camargo; O'Dwyer, Lucia Helena

    2013-12-01

    Hepatozoon canis is a common apicomplexan parasite of dogs. In Brazil, in addition to Rhipicephalus sanguineus, Amblyomma ovale, Amblyomma cajennense, and Rhipicephalus (Boophilus) microplus have been suggested to act as vectors. The present study aimed to evaluate, under controlled conditions, the acquisition of H. canis by A. ovale, R. sanguineus, and A. cajennense after feeding on naturally infected dogs. Cytological and histophatological examinations were performed to recover oocysts and other sporogonic stages of the protozoan from the experimentally infected nymphs and adults. None of the R. sanguineus (n=30) or A. cajennense nymphs (n=15) that were dissected after feeding on H. canis naturally infected dogs became infected by the hemoparasite. Likewise, none of the R. sanguineus (n=165) and A. cajennense (n=114) adult ticks that were fed as nymphs on dogs demonstrated infection. Additionally, A. cajennense adult ticks were incapable of acquiring the infection, since no parasite was found in 62 adults that fed on H. canis-infected dogs. With regard to A. ovale ticks, 2 different infestations were carried out. Firstly, a dog with naturally occurring hepatozoonosis was infested with A. ovale adults originating from Rondônia, Brazil. Ticks fed to full engorgement. A total of 31 adults was collected from the dog and dissected on the third day after natural detachment. Oocysts were detected in 13 (42%) of the ticks. The second experimental infestation was carried out using adult ticks originating from São Paulo, Brazil. Surprisingly, of the 103 dissected ticks, only one (1%) contained oocysts in the hemocoel. No other sporogonic stage was found. Results indicate that different strains of A. ovale ticks may exist in Brazil with different susceptibilities to pathogens. Furthermore, it is possible that R. sanguineus and A. cajennense have little or no importance in the transmission of H. canis in rural areas of Brazil. Copyright © 2013 Elsevier GmbH. All rights

  11. Life cycle of Hepatozoon canis (Apicomplexa: Adeleorina: Hepatozoidae) in the tick Rhipicephalus sanguineus and domestic dog (Canis familiaris).

    Science.gov (United States)

    Baneth, Gad; Samish, Michael; Shkap, Varda

    2007-04-01

    The life cycle of the apicomplexan protozoon Hepatozoon canis in its natural hosts Rhipicephalus sanguineus (tick) and Canis familiaris (domestic dog) was studied in an experimental infection. Tick nymphs were fed on a naturally infected dog, or they were infected by percutaneous injection of blood. Dogs were inoculated by ingestion of adult ticks containing mature oocysts. Gamonts were in syzygy 24 hr after percutaneous injection of ticks. Early oocysts were detected 96 hr after nymph repletion, and mature oocysts in adult ticks were infective to dogs 40 days postmolt. Merogony was detected in dog bone marrow from 13 days postinoculation (PI) and included meronts containing 20-30 micromerozoites, and a second type with 2-4 macromerozoites. Monozoic cysts were observed in the spleen in conjunction with merogony. Gamontogony with infection of leukocytes by micromerozoites occurred from 26 days PI, and gamont parasitemia, which completed the life cycle, was detected 28 days PI. The length of the life cycle from nymphal attachment to parasitemia in dogs was 81 days. Increased body temperatures were evident from 16 to 27 days PI and paralleled the time of intensive bone marrow merogony. Skeletal pain and recumbency were manifested in 2 dogs. This study further elucidates the life cycle of H. canis and provides a sequential morphologic description of H. canis merogony, gamontogony, and sporogony.

  12. The Study on the Penalty Function of the Insurance Company When the Stock Price Follows Exponential Lévy Process

    Science.gov (United States)

    Wu, Zhao; Ding-Cheng, Wang; Yong, Zeng

    This paper investigates the penalty function under the condition that the insurance company is allowed to invest certain amount of money in some stock market and the remaining reserve in the bond with constant interest force. Through the properties of exponential Lévy process and discrete embedded method, the integral equations for penalty function is derived under the assumption that the stock price follows exponential Lévy process. The method for explicitly computing the ruin quantities is obtained.

  13. The “Lévy or Diffusion” Controversy: How Important Is the Movement Pattern in the Context of Trapping?

    OpenAIRE

    Danish A. Ahmed; Sergei V. Petrovskii; Paulo F. C. Tilles

    2018-01-01

    Many empirical and theoretical studies indicate that Brownian motion and diffusion models as its mean field counterpart provide appropriate modeling techniques for individual insect movement. However, this traditional approach has been challenged, and conflicting evidence suggests that an alternative movement pattern such as Lévy walks can provide a better description. Lévy walks differ from Brownian motion since they allow for a higher frequency of large steps, resulting in a f...

  14. The Pacman Perforator-Based V-Y Advancement Flap for Reconstruction of Pressure Sores at Different Locations.

    Science.gov (United States)

    Bonomi, Stefano; Salval, André; Brenta, Federica; Rapisarda, Vincenzo; Settembrini, Fernanda

    2016-09-01

    Many procedures have been proposed for the treatment of pressure sores, and V-Y advancement flaps are widely used to repair a defect. Unfortunately, the degree of mobility of a V-Y advancement flap is dependent on the laxity of the underlying subcutaneous tissue. This is an important disadvantage of traditional V-Y advancement flap and limits its use.We used V-Y advancement flaps as perforator-based to overcome mobility restriction problem, with a further modification (Pacman-like shape) to improve the covering surface area of the flap. Between January 2012 and December 2014, the authors used 37 V-Y Pacman perforator-based flaps in 33 consecutive patients for coverage of defects located at sacral (n = 21), ischial (n = 13), trochanter (n = 1) regions. There were 27 male and 6 female patients with a mean age of 49.9 years (range, 15-74 years). All flaps survived completely (92.3%) except 3 in which one of them had undergone total necrosis due to hematoma and the other 2 had partial necrosis. No venous congestion was observed. The mean follow-up period was 14.9 months (range, 2-38 months). No flap surgery-related mortality or recurrence of pressure sores was noted. The V-Y Pacman perforator-based advancement flaps are safe and very effective for reconstruction of pressure sores at various regions. The advantage of our modification procedure include shorter operative time, lesser pedicle dissection, low donor site morbidity, good preservation of muscle, and offers remarkable excursion to the V-Y flap, which make the V-Y Pacman perforator-based flaps an excellent choice for large pressure sore coverage.

  15. Anti-Hepatozoon canis serum antibodies and gamonts in naturally-occurring canine monocytic ehrlichiosis.

    Science.gov (United States)

    Mylonakis, Mathios E; Leontides, Leonidas; Gonen, Liat; Billinis, Charalambos; Koutinas, Alexander F; Baneth, Gad

    2005-05-15

    The prevalence of IgG antibodies to Hepatozoon canis and the presence of gamonts in the blood and hemolymphatic tissues were studied in dogs with canine monocytic ehrlichiosis (CME) caused by Ehrlichia canis. Both pathogens are transmitted by the tick Rhipicephalus sanguineus. Forty-five out of 69 (65.2%) dogs with CME were seropositive to H. canis by an enzyme-linked immunosorbent assay (ELISA). Intra-neutrophilic gamonts of H. canis were found in 2 out of 69 dogs (2.9%) comprising 4.5% of the seropositive dogs. The present study indicated that the prevalence of antibodies to H. canis was high among dogs with CME in an area where both infections are endemic. However, previous exposure to H. canis was not found as an important contributor to clinical or clinicopathologic abnormalities found in dogs with CME.

  16. Description of dogs naturally infected with Hepatozoon canis in the Aegean region of Turkey

    OpenAIRE

    PAŞA, Serdar; KIRAL, Funda; KARAGENÇ, Tülin; ATASOY, Abidin; SEYREK, Kamil

    2009-01-01

    Clinical and laboratory findings recorded in 10 dogs naturally infected with Hepatozoon canis in the Aegean region of Turkey were reported. The diagnosis was made by finding H. canis gamonts within leucocytes in Giemsa-stained blood smears. H. canis parasitaemia level was calculated manually by counting 500 neutrophils in blood smears. Parasitaemia varied from 1% to 23% of the circulating neutrophils. Anorexia, fever, depression, weight loss, and lymphadenopathy are the main clinical signs in...

  17. Molecular cloning and characterization of arginine kinase gene of Toxocara canis

    OpenAIRE

    Sahu, Shivani; Samanta, S.; Harish, D. R.; Sudhakar, N. R.; Raina, O. K.; Shantaveer, S. B.; Madhu, D. N.; Kumar, Ashok

    2013-01-01

    Toxocara canis is an important gastrointestinal nematode of dogs and also a causative agent of visceral larva migrans in humans. Arginine kinase (AK) gene is one of the important biomolecule of phosphagen kinase of T. canis which is emerging as an exciting novel diagnostic target in toxocarosis. The present study was carried out to clone and characterize AK gene of T. canis for future utilization as a diagnostic molecule. Total RNA was extracted from intact adult worms and reverse transcripti...

  18. MASTICATORY MUSCLE MYOSITIS IN A GRAY WOLF (CANIS LUPUS).

    Science.gov (United States)

    Kent, Marc; Glass, Eric N; Castro, Fernando A; Miller, Andrew D; de Lahunta, Alexander

    2017-03-01

    A 10-yr-old male, neutered gray wolf ( Canis lupus ) was presented for atrophy of the temporalis and masseter muscles. Clinical signs and magnetic resonance imaging were consistent with a myopathy. Positive serology for antibody titers directed against Type 2M myofibers, and the observation of a mixed mononuclear inflammatory cell infiltrate along with eosinophils and neutrophils within the temporalis muscle, were diagnostic for masticatory muscle myositis. Importantly, protozoal myositis was excluded based on other clinicopathologic data. The case highlights the potential for immune-mediated polymyositis in canids other than the domesticated dog ( Canis lupus familaris). Additionally, awareness of a diet in which raw meat is used should prompt a thorough investigation for an underlying infectious myositis in the gray wolf.

  19. Giardia and Cryptosporidium species and genotypes in coyotes (Canis latrans).

    Science.gov (United States)

    Trout, James M; Santín, Mónica; Fayer, Ronald

    2006-06-01

    Feces and duodenal scrapings were collected from 22 coyotes (Canis latrans) killed in managed hunts in northeastern Pennsylvania. Polymerase chain reaction (PCR) methods were used to detect Giardia and Cryptosporidium spp. PCR-amplified fragments of Giardia and Cryptosporidium spp. SSU-rRNA genes were subjected to DNA sequence analysis for species/genotype determination. Seven coyotes (32%) were positive for G. duodenalis: three assemblage C, three assemblage D, and one assemblage B. Six coyotes (27%) were positive for Cryptosporidium spp. One isolate shared 99.7% homology with C. muris, whereas five others (23%) shared 100% homology with C. canis, coyote genotype. This is the first report on multiple genotypes of Giardia spp. in coyotes and on the prevalence of Cryptosporidium spp. genotypes in coyotes.

  20. Haematopathological Changes in Dogs Affected with Ehrlichia Canis in Lesvos

    Directory of Open Access Journals (Sweden)

    Geromichalou A.

    2017-06-01

    Full Text Available Canine Ehrlichiosis is an important immunosuppressive tick borne disease in dogs. The geographical distribution and transmission is mostly related with Rhipicephalus sanguineus which acts as a vector. There is no predilection of age or sex; all breeds may be infected with Canine Monocytic Ehrlichiosis (CME. The primary targets are monocytic cells. Platelet disorders and serum protein alterations are the principal hematological and biochemical consequences of infections. Clinical signs are almost non-specific. A definitive diagnosis requires: visualization of morulae within monocytes on cytology, detection of serum antibodies with E. canis, the IFA test, or the PCR. The objective of this study was to present information about haematological and biochemical tests of E. canis infected dogs in Lesvos island in Greece, which is an endemic area.

  1. SCM, the M Protein of Streptococcus canis Binds Immunoglobulin G.

    Science.gov (United States)

    Bergmann, Simone; Eichhorn, Inga; Kohler, Thomas P; Hammerschmidt, Sven; Goldmann, Oliver; Rohde, Manfred; Fulde, Marcus

    2017-01-01

    The M protein of Streptococcus canis (SCM) is a virulence factor and serves as a surface-associated receptor with a particular affinity for mini-plasminogen, a cleavage product of the broad-spectrum serine protease plasmin. Here, we report that SCM has an additional high-affinity immunoglobulin G (IgG) binding activity. The ability of a particular S. canis isolate to bind to IgG significantly correlates with a scm -positive phenotype, suggesting a dominant role of SCM as an IgG receptor. Subsequent heterologous expression of SCM in non-IgG binding S. gordonii and Western Blot analysis with purified recombinant SCM proteins confirmed its IgG receptor function. As expected for a zoonotic agent, the SCM-IgG interaction is species-unspecific, with a particular affinity of SCM for IgGs derived from human, cats, dogs, horses, mice, and rabbits, but not from cows and goats. Similar to other streptococcal IgG-binding proteins, the interaction between SCM and IgG occurs via the conserved Fc domain and is, therefore, non-opsonic. Interestingly, the interaction between SCM and IgG-Fc on the bacterial surface specifically prevents opsonization by C1q, which might constitute another anti-phagocytic mechanism of SCM. Extensive binding analyses with a variety of different truncated SCM fragments defined a region of 52 amino acids located in the central part of the mature SCM protein which is important for IgG binding. This binding region is highly conserved among SCM proteins derived from different S. canis isolates but differs significantly from IgG-Fc receptors of S. pyogenes and S. dysgalactiae sub. equisimilis , respectively. In summary, we present an additional role of SCM in the pathogen-host interaction of S. canis . The detailed analysis of the SCM-IgG interaction should contribute to a better understanding of the complex roles of M proteins in streptococcal pathogenesis.

  2. Denning behaviour of non-gravid wolves, Canis lupus

    Science.gov (United States)

    Mech, L.D.; Phillips, M.K.; Smith, D.W.; Kreeger, T.J.

    1996-01-01

    Wild wolves (Canis lupus) that had produced pups in earlier years but were not currently pregnant, and ovariectomized captive wolves, dug dens during and after the whelping season even though they produced no pups. These observations suggest that den digging is not a function of pregnancy or of ovarian estrogen or progesterone. We hypothesize that increasing prolactin in spring elicits or mediates den-digging behavior.

  3. Molecular and serological detection of Ehrlichia canis and Babesia vogeli in dogs in Colombia.

    Science.gov (United States)

    Vargas-Hernández, G; André, M R; Faria, J L M; Munhoz, T D; Hernandez-Rodriguez, M; Machado, R Z; Tinucci-Costa, M

    2012-05-25

    Ehrlichiosis and babesiosis are tick-borne diseases, caused mainly by Ehrlichia canis and Babesia canis, respectively, with a worldwide occurrence in dogs, whose main vector is the brown-dog tick, Rhipicephalus sanguineus. The present work aimed to detect the presence of E. canis and Babesia sp. in 91 dog blood samples in Colombia, by molecular and serological techniques. We also performed sequence alignment to indicate the identity of the parasite species infecting these animals. The present work shows the first molecular detection of E. canis and B. vogeli in dogs from Colombia. Immunoglobulin-G (IgG) antibodies to E. canis and Babesia vogeli were found in 75 (82.4%) and 47 (51.6%) sampled dogs, respectively. Thirty-seven (40.6%) and 5 (5.5%) dogs were positive in PCR for E. canis and Babesia sp., respectively. After sequencing, amplicons showed 99% of identity with isolates of E. canis and B. vogeli. The phylogenetic trees based on 16S rRNA-Anaplasmataceae sequences and 18S rRNA-piroplasmid sequences supported the identity of the found E. canis and B. vogeli DNAs, respectively. The present work shows the first molecular detection of E. canis and B. vogeli in dogs in Colombia. Copyright © 2011 Elsevier B.V. All rights reserved.

  4. Real-time monitoring of Lévy flights in a single quantum system

    Science.gov (United States)

    Issler, M.; Höller, J.; Imamoǧlu, A.

    2016-02-01

    vy flights are random walks where the dynamics is dominated by rare events. Even though they have been studied in vastly different physical systems, their observation in a single quantum system has remained elusive. Here we analyze a periodically driven open central spin system and demonstrate theoretically that the dynamics of the spin environment exhibits Lévy flights. For the particular realization in a single-electron charged quantum dot driven by periodic resonant laser pulses, we use Monte Carlo simulations to confirm that the long waiting times between successive nuclear spin-flip events are governed by a power-law distribution; the corresponding exponent η =-3 /2 can be directly measured in real time by observing the waiting time distribution of successive photon emission events. Remarkably, the dominant intrinsic limitation of the scheme arising from nuclear quadrupole coupling can be minimized by adjusting the magnetic field or by implementing spin echo.

  5. Evolution of optimal Lévy-flight strategies in human mental searches

    Science.gov (United States)

    Radicchi, Filippo; Baronchelli, Andrea

    2012-06-01

    Recent analysis of empirical data [Radicchi, Baronchelli, and Amaral, PloS ONE1932-620310.1371/journal.pone.0029910 7, e029910 (2012)] showed that humans adopt Lévy-flight strategies when exploring the bid space in online auctions. A game theoretical model proved that the observed Lévy exponents are nearly optimal, being close to the exponent value that guarantees the maximal economical return to players. Here, we rationalize these findings by adopting an evolutionary perspective. We show that a simple evolutionary process is able to account for the empirical measurements with the only assumption that the reproductive fitness of the players is proportional to their search ability. Contrary to previous modeling, our approach describes the emergence of the observed exponent without resorting to any strong assumptions on the initial searching strategies. Our results generalize earlier research, and open novel questions in cognitive, behavioral, and evolutionary sciences.

  6. Comparing Multicomponent Erlang Distribution and Lévy Distribution of Particle Transverse Momentums

    International Nuclear Information System (INIS)

    Wei, Hua-Rong; Chen, Ya-Hui; Gao, Li-Na; Liu, Fu-Hu

    2014-01-01

    The transverse momentum spectrums of final-state products produced in nucleus-nucleus and proton-proton collisions at different center-of-mass energies are analyzed by using a multicomponent Erlang distribution and the Lévy distribution. The results calculated by the two models are found in most cases to be in agreement with experimental data from the Relativistic Heavy Ion Collider (RHIC) and the Large Hadron Collider (LHC). The multicomponent Erlang distribution that resulted from a multisource thermal model seems to give a better description as compared with the Lévy distribution. The temperature parameters of interacting system corresponding to different types of final-state products are obtained. Light particles correspond to a low temperature emission, and heavy particles correspond to a high temperature emission. Extracted temperature from central collisions is higher than that from peripheral collisions

  7. Self-organisation of random oscillators with Lévy stable distributions

    Science.gov (United States)

    Moradi, Sara; Anderson, Johan

    2017-08-01

    A novel possibility of self-organized behaviour of stochastically driven oscillators is presented. It is shown that synchronization by Lévy stable processes is significantly more efficient than that by oscillators with Gaussian statistics. The impact of outlier events from the tail of the distribution function was examined by artificially introducing a few additional oscillators with very strong coupling strengths and it is found that remarkably even one such rare and extreme event may govern the long term behaviour of the coupled system. In addition to the multiplicative noise component, we have investigated the impact of an external additive Lévy distributed noise component on the synchronisation properties of the oscillators.

  8. Didelphis albiventris naturally infected with Hepatozoon canis in southeastern Brazil.

    Science.gov (United States)

    da Silva, Maria Regina Lucas; Fornazari, Felipe; Demoner, Larissa de Castro; Teixeira, Carlos Roberto; Langoni, Helio; O'Dwyer, Lucia Helena

    2017-10-01

    Hepatozoon species are vector-borne pathogens that infect domestic and wild animals. Marsupials of the species Didelphis albiventris are adapted to urban and peri-urban areas and act as reservoir hosts for several parasites. The present study evaluated the occurrence of infection by Hepatozoon species in synantropic D. albiventris from Botucatu, São Paulo, Brazil. Blood samples and ectoparasites from 19 D. albiventris were collected from urban and peri-urban areas. Hepatozoon spp. detection was performed by microscopy and molecular analysis. One opossum was positive for Hepatozoon spp. in microscopy analysis and PCR, while another animal was positive only in PCR. The obtained sequences were 100% identical to Hepatozoon canis. Six species of ticks and two species of fleas were detected on D. albiventris. This is the first report of H. canis in synantropic D. albiventris. In Brazil, H. canis transmission among dog populations is not well established, which highlights the importance of investigating the role that opossums might play in the epidemiology of this protozoan. Copyright © 2017 Elsevier GmbH. All rights reserved.

  9. Molecular characterization of Hepatozoon canis in dogs from Colombia.

    Science.gov (United States)

    Vargas-Hernandez, Giovanni; André, Marcos R; Munhoz, Thiago D; Faria, Joice M L; Machado, Rosangela Z; Tinucci-Costa, Mirela

    2012-01-01

    Hepatozoonosis is a tick-borne disease whose transmission to dogs occurs by ingestion of oocysts infected ticks or feeding on preys infested by infected ticks. Until now, there is no previous report of molecular characterization of Hepatozoon sp. in dogs from Colombia. EDTA blood samples were collected from 91 dogs from central-western region of Colombia (Bogotá, Bucaramanga, and Villavicencio cities) and submitted to 18S rRNA Hepatozoon sp. PCR and blood smears confection. Phylogenetic analysis was used to access the identity of Hepatozoon species found in sampled dogs. From 91 sampled dogs, 29 (31.8%) were positive to Hepatozoon sp. (25 dogs were only positive in PCR, 1 was positive only in blood smears, and 3 were positive in both blood smears and PCR). After sequencing, the found Hepatozoon sp. DNA showed 100% of identity with Hepatozoon canis DNA isolates. The phylogenetic tree supported the identity of the found Hepatozoon sp. DNA, showing that the isolates from Colombia were placed in the same clade than other H. canis isolates from Venezuela, Spain, and Taiwan. This is the first molecular detection of H. canis in dogs from Colombia.

  10. Molecular detection of Hepatozoon canis in dogs from Kerala.

    Science.gov (United States)

    Lakshmanan, Bindu; Jose, K Jain; George, Arun; Usha, N P; Devada, K

    2018-06-01

    India has a wide range of agro-climatic zones which is highly conducive for a diverse range of vectors and canines are continuously exposed to the risk of spectrum of tick borne protozoan diseases. The brown dog tick, Rhipicephalus sanguineus is widely prevalent among dogs in Kerala and there is a high prevalence of this tick transmitted Babesia and Ehrlichia spp. infection. However, the incidence of Hepatozoon canis transmitted by the same tick species had not been reported in the state since 2004. Preliminary screening of client owned dogs revealed six dogs to be positive for typical gelatin capsule shaped gamonts of H. canis within neutrophils in blood smear by microscopic examination. A PCR assay was standardized to amplify a specific 737 bp fragment of 18S rRNA gene of H. canis. Phylogenetic analysis revealed closest relationship with West Indies isolate deposited at GenBank database. The present study records the molecular detection of this haemoparasite in the state, for the first time.

  11. Comparative study of Microsporum canis isolates by DNA fingerprinting.

    Science.gov (United States)

    Shafiee, Shabnam; Khosravi, Ali Reza; Ashrafi Tamai, Iradj

    2014-08-01

    Microsporum canis is a zoophilic fungus and it is an important agent of dermatophytosis. Cats act as important reservoirs. Clinically, it is too difficult to differentiate dermatophytosis caused by various species, also this fungus loses its morphological characteristics easily because of subculture; so using of rapid and accurate laboratory techniques for identifying the dermatophytes is important, therefore, RAPD-PCR was applied for the differentiation of the isolates. In this study, 10 M. canis isolates were detected in cats, dog, human, fox and rabbit at the Mycology Research Center, Faculty of Veterinary Medicine, University of Tehran. For running the RAPD-PCR, PCR set system and three random primers OPU 15, OPU 13 and OPA 04 were used. Then phylogenetic tree and similarity coefficient table were drawn. The results showed that there were some common bands between M. canis isolates. There were some specific bands for each isolates, as well. Our study showed, despite the typical morphology of the whole isolates, they were placed in different branches in molecular typing. © 2014 Blackwell Verlag GmbH.

  12. Seroprevalence of Ehrlichia canis infection in stray dogs from Serbia

    Directory of Open Access Journals (Sweden)

    Nataša Bogićević

    2017-03-01

    Full Text Available Canine Monocytic Ehrlichiosis is a zoonotic bacterial disease with worldwide distribution. With regards to the population of stray dogs, the disease is facilitated due to their lifestyle and the lack of anti-parasitic protection. The aim of this study was to provide serological data on the presence of a specific Ehrlichia canis IgG antibodies in stray dogs, originating from 7 municipalities in Serbia. During the period from April 2013 to June 2014, 217 canine sera were submitted to the laboratory of the Department of Infectious Diseases of Animals and Bees, Faculty of Veterinary Medicine in Belgrade. An immunofluorescent antibody test (IFAT was performed to detect antibodies to Ehrlichia canis (cut off, 1:50. Seropositive dogs were found in 5 out of 7 counties with a seroprevalence varying from 3.57% to 20% and an overall seroprevalence of 11.06% (24/217. There was no statistically significant difference between the prevalence of infection and the host age or gender. Results showed that stray dogs contribute to maintaining and spreading of Ehrlichia canis in Serbia. Due to the close relationship between people and dogs, it is of great importance to constantly monitor and improve prevention of this disease.

  13. Effect of Saprotrophic Soil Fungi on Toxocara canis Eggs

    Directory of Open Access Journals (Sweden)

    Ciarmela, M. L.

    2010-01-01

    Full Text Available The purpose of this work was to assess the ovicidal activity of Chrysosporium merdarium, Trichoderma harzianum, Fusarium oxysporum, F. moniliforme and F. sulphureum isolated from public areas in the city of La Plata, Argentina, on Toxocara canis eggs in vitro. Each species were cultured on water agar 2% with a suspension of immature-stage T. canis eggs. At 4, 7, 14, 21 and 28 days post-culture, they were observed by light and scanning electron microscopy. One hundred eggs were evaluated and scored according to Lỳsek’s ovicidal effect classification. These procedures were repeated three times which each fungal species. Chrysosporium merdarium and F. oxysporum showed very high ovicidal activity, F. sulphureum high ovicidal activity, F. moniliforme intermediate ovicidal activity and T. harzianum did not affect the viability of T. canis eggs. Taking into account the effects on human and animal health and the environment, the species with better prospects for studying its potential use as biological control was F. sulphureum.

  14. ENCUESTA EXPLORATORIA DE INFECCION POR Brucella canis EN PERROS DE

    Directory of Open Access Journals (Sweden)

    Ana Pardo D

    2009-08-01

    Full Text Available Objetivo. Determinar la presencia de anticuerpos a B. canis en perros domésticos y callejeros del municipio de Villavicencio, Colombia. Materiales y métodos. Se utilizó la prueba de aglutinación rápida en placa con antígeno menos mucoide (M- en 201 muestras de suero. En dos animales seropositivos se realizó intento de aislamiento por hemocultivo en medio selectivo para Brucella (oxoid®. En un animal seropositivo, con crecimiento bacteriano con características morfológicas sugestivas a B. canis se realizó histopatología de testículo, bazo e hígado. Resultados. La seropositividad general fue de 1.49% y correspondió a tres caninos machos, dos de los cuales presentaron signos clínicos de epididimitis y orquitis (unilateral. El cultivo y la histopatología no fueron concluyentes para el diagnostico de B. canis. Conclusiones. La seropositividad fue baja y sugiere que la población estudiada no ha estado en contacto con la bacteria. La presencia de reactores puede estar asociado con falsos positivos. El no aislamiento de la bacteria no indica que la enfermedad no exista por lo que se requiere de nuevos estudios.

  15. A comparative study of results of the von Langenbeck and the V-Y pushback palatoplasties.

    Science.gov (United States)

    Krause, C J; Tharp, R F; Morris, H L

    1976-01-01

    The incidence of velopharyngeal competence noted in 267 cleft palate patients following palatoplsty has been reviewed. Comparisons have been drawn with regard to the cleft type and the surgical technique performed. Since there were relatively small numbers of subjects in some categories, differences in age at last examination between the von Langenbeck and V-Y palatoplasty groups, some patients were very young at time of evaluation, and a number of different surgeons at different levels of training and experience performed the surgery, the differences in velopharyngeal competence found should be viewed as trends and this report as preliminary. In general, there was a trend toward smaller percentages of patients attaining acceptable velopharyngeal competence as the severity of the cleft increased. Of those with clefts of the soft palate only 86 per cent achieved competence. Among those patients with clefts of the palate only, 67 per cent achieved competence, whereas only 57 per cent of those with clefts of the lip and palate were able to do so. When comparing all cleft types, the V-Y palatoplasty resulted in a significantly higher percentage of velopharyngeal competence (74 per cent) than did the von Langenbeck method (56 per cent), although the data for the V-Y group are probably less reliable than those for the von Langenbeck group. In the soft palate only category, the results were slightly better with the von Langenbeck technique, though not significantly so. In all other cleft types, the results with the V-Y method were better than those with the von Langenbeck.

  16. Nonparametric adaptive estimation of linear functionals for low frequency observed Lévy processes

    OpenAIRE

    Kappus, Johanna

    2012-01-01

    For a Lévy process X having finite variation on compact sets and finite first moments, µ( dx) = xv( dx) is a finite signed measure which completely describes the jump dynamics. We construct kernel estimators for linear functionals of µ and provide rates of convergence under regularity assumptions. Moreover, we consider adaptive estimation via model selection and propose a new strategy for the data driven choice of the smoothing parameter.

  17. Analogies between colored Lévy noise and random channel approach to disordered kinetics

    Science.gov (United States)

    Vlad, Marcel O.; Velarde, Manuel G.; Ross, John

    2004-02-01

    We point out some interesting analogies between colored Lévy noise and the random channel approach to disordered kinetics. These analogies are due to the fact that the probability density of the Lévy noise source plays a similar role as the probability density of rate coefficients in disordered kinetics. Although the equations for the two approaches are not identical, the analogies can be used for deriving new, useful results for both problems. The random channel approach makes it possible to generalize the fractional Uhlenbeck-Ornstein processes (FUO) for space- and time-dependent colored noise. We describe the properties of colored noise in terms of characteristic functionals, which are evaluated by using a generalization of Huber's approach to complex relaxation [Phys. Rev. B 31, 6070 (1985)]. We start out by investigating the properties of symmetrical white noise and then define the Lévy colored noise in terms of a Langevin equation with a Lévy white noise source. We derive exact analytical expressions for the various characteristic functionals, which characterize the noise, and a functional fractional Fokker-Planck equation for the probability density functional of the noise at a given moment in time. Second, by making an analogy between the theory of colored noise and the random channel approach to disordered kinetics, we derive fractional equations for the evolution of the probability densities of the random rate coefficients in disordered kinetics. These equations serve as a basis for developing methods for the evaluation of the statistical properties of the random rate coefficients from experimental data. Special attention is paid to the analysis of systems for which the observed kinetic curves can be described by linear or nonlinear stretched exponential kinetics.

  18. Tempered Lévy walk of charged particles in turbulent magnetic field

    International Nuclear Information System (INIS)

    Sibatov, R T; Uchaikin, V V; Byzykchi, A N

    2017-01-01

    Recently, various diffusion regimes of ions and electrons in interplanetary magnetic field have been recognized from the data collected by different spacecrafts. Particularly for protons, superdiffusion and normal diffusion parallel to the mean magnetic field were declared, simulation also predicts transient superdiffusive behavior. We interpret parallel motion in terms of the one-dimensional tempered Lévy walk process and show that this representation is consistent with the experimental and simulated results. (paper)

  19. Time-series photometric spot modeling. I - Parameter study and application to HD 17433 = VY Arietis

    Science.gov (United States)

    Strassmeier, K. G.; Bopp, B. W.

    1992-01-01

    New UBVRI photometry of the active chromosphere binary HD 17433 (VY) Ari from 1987 through 1991 is presented, and the long-term and short-term spot behavior is studied. A 0.2 mag variation of the mean brightness and a maximum wave amplitude of up to 0.4 mag in 1988 are found. The newly measured photometric period of 16.42 d suggests asynchronous rotation of the primary component by about 30 percent.

  20. ASYMPTOTICS FOR EXPONENTIAL LÉVY PROCESSES AND THEIR VOLATILITY SMILE: SURVEY AND NEW RESULTS

    OpenAIRE

    LEIF ANDERSEN; ALEXANDER LIPTON

    2013-01-01

    Exponential Lévy processes can be used to model the evolution of various financial variables such as FX rates, stock prices, and so on. Considerable efforts have been devoted to pricing derivatives written on underliers governed by such processes, and the corresponding implied volatility surfaces have been analyzed in some detail. In the non-asymptotic regimes, option prices are described by the Lewis-Lipton formula, which allows one to represent them as Fourier integrals, and the prices can ...

  1. Integer-valued Lévy processes and low latency financial econometrics

    DEFF Research Database (Denmark)

    Barndorff-Nielsen, Ole; Pollard, David G.; Shephard, Neil

    Motivated by features of low latency data in financial econometrics we study in detail integervalued Lévy processes as the basis of price processes for high frequency econometrics. We propose using models built out of the difference of two subordinators. We apply these models in practice to low...... latency data for a variety of different types of futures contracts.futures markets, high frequency econometrics, low latency data, negative binomial, Skellam, tempered stable...

  2. Photon assisted Lévy flights of minority carriers in n-InP

    International Nuclear Information System (INIS)

    Semyonov, Oleg; Subashiev, Arsen V.; Chen Zhichao; Luryi, Serge

    2012-01-01

    We study the photoluminescence spectra of n-doped InP bulk wafers, both in the reflection and the transmission geometries relative to the excitation beam. From the observed spectra we estimate the spatial distribution of minority carriers allowing for the spectral filtering due to reabsorption of luminescence in the wafer. This distribution unambiguously demonstrates a non-exponential drop-off with distance from the excitation region. Such a behavior evidences an anomalous photon-assisted transport of minority carriers enhanced owing to the high quantum efficiency of emission. It is shown that the transport conforms very well to the so-called Lévy-flights process corresponding to a peculiar random walk that does not reduce to diffusion. The index γ of the Lévy flights distribution is found to be in the range γ=0.64–0.79, depending on the doping. Thus, we propose the high-efficiency direct-gap semiconductors as a remarkable laboratory system for studying the anomalous transport. - Highlights: ► Spatial distribution of minority carriers is found from photoluminescence spectra. ► The distribution shows a power-law drop-off with distance from the excitation plane. ► The photon-assisted transport is a random walk well described by the Lévy flight. ► Emission quantum efficiency of n-InP is independently determined. ► Results are in excellent agreement with earlier luminescence kinetics experiments.

  3. Current status and future directions of Lévy walk research

    Science.gov (United States)

    2018-01-01

    ABSTRACT Lévy walks are a mathematical construction useful for describing random patterns of movement with bizarre fractal properties that seem to have no place in biology. Nonetheless, movement patterns resembling Lévy walks have been observed at scales ranging from the microscopic to the ecological. They have been seen in the molecular machinery operating within cells during intracellular trafficking, in the movement patterns of T cells within the brain, in DNA, in some molluscs, insects, fish, birds and mammals, in the airborne flights of spores and seeds, and in the collective movements of some animal groups. Lévy walks are also evident in trace fossils (ichnofossils) – the preserved form of tracks made by organisms that occupied ancient sea beds about 252-66 million years ago. And they are utilised by algae that originated around two billion years ago, and still exist today. In September of 2017, leading researchers from across the life sciences, along with mathematicians and physicists, got together at a Company of Biologists' Workshop to discuss the origins and biological significance of these movement patterns. In this Review the essence of the technical and sometimes heated discussions is distilled and made accessible for all. In just a few pages, the reader is taken from a gentle introduction to the frontiers of a very active field of scientific enquiry. What emerges is a fascinating story of a truly inter-disciplinary scientific endeavour that is seeking to better understand movement patterns occurring across all biological scales. PMID:29326297

  4. Innovation in the planning of V-Y rotation advancement flaps: A template for flap design

    Directory of Open Access Journals (Sweden)

    Utku Can Dölen

    2018-01-01

    Full Text Available Local flaps exhibit excellent color matching that no other type of flap can compete with. Moreover, surgery using a local flap is easier and faster than surgery using a distant or free flap. However, local flaps can be much more difficult to design. We designed 2 templates to plan a V-Y rotation advancement flap. The template for a unilateral V-Y rotation advancement flap was used on the face (n=5, anterior tibia (n=1, posterior axilla (n=1, ischium (n=1, and trochanter (n=2. The template for a bilateral flap was used on the sacrum (n=8, arm (n=1, and anterior tibia (n=1. The causes of the defects were meningocele (n=3, a decubitus ulcer (n=5, pilonidal sinus (n=3, and skin tumor excision (n=10. The meningocele patients were younger than 8 days. The mean age of the adult patients was 50.4 years (range, 19–80 years. All the donor areas of the flaps were closed primarily. None of the patients experienced wound dehiscence or partial/total flap necrosis. The templates guided surgeons regarding the length and the placement of the incision for a V-Y rotation advancement flap according to the size of the wound. In addition, they could be used for the training of residents.

  5. Reconstruction in extensive axillary Hidradenitis suppurativa with local fasciocutaneous V-Y advancement flaps

    Directory of Open Access Journals (Sweden)

    Sharma Ramesh

    2006-01-01

    Full Text Available We present our experience with the use of local fasciocutaneous V-Y advancement flaps in the reconstruction of 10 axillae in 6 patients for large defects following wide excision of long-standing Hidradenitis suppurativa of the axilla. The defects were closed with local V-Y subcutaneous island flaps. A single flap from the chest wall was sufficient for moderate defects. However, for larger defects, an additional flap was taken from the medial side of the ipsilateral arm. The donor defects could be closed primarily in all the patients. The local areas of the lateral chest wall and the medial side of the arm have a plentiful supply of cutaneous perforators and the flaps can be designed in a V-Y fashion without resorting to preoperative marking of the perforator. The flaps were freed sufficiently to allow adequate movement for closure of the defects. Although no attempt was made to identify the perforators specifically, many perforators were seen entering the flap. Some perforators can be safely divided to increase reach of the flap. All the flaps survived completely. A follow up of 2.5 years is presented.

  6. Synchronisation of networked Kuramoto oscillators under stable Lévy noise

    Science.gov (United States)

    Kalloniatis, Alexander C.; Roberts, Dale O.

    2017-01-01

    We study the Kuramoto model on several classes of network topologies examining the dynamics under the influence of Lévy noise. Such noise exhibits heavier tails than Gaussian and allows us to understand how 'shocks' influence the individual oscillator and collective system behaviour. Skewed α-stable Lévy noise, equivalent to fractional diffusion perturbations, are considered. We perform numerical simulations for Erdős-Rényi (ER) and Barabási-Albert (BA) scale free networks of size N = 1000 while varying the Lévy index α for the noise. We find that synchrony now assumes a surprising variety of forms, not seen for Gaussian-type noise, and changing with α: a noise-generated drift, a smooth α dependence of the point of cross-over of ER and BA networks in the degree of synchronisation, and a severe loss of synchronisation at low values of α. We also show that this robustness of the BA network across most values of α can also be understood as a consequence of the Laplacian of the graph working within the fractional Fokker-Planck equation of the linearised system, close to synchrony, with both eigenvalues and eigenvectors alternately contributing in different regimes of α.

  7. Cross-infection between cats and cows: Origin and control of Streptococcus canis mastitis in a dairy herd

    OpenAIRE

    Tikofsky, L L; Zadoks, R N

    2005-01-01

    Group G streptococci in animals usually belong to the species Streptococcus canis and are most commonly found in dogs and cats. Occasionally, Strep. canis is detected in milk from dairy cows. An outbreak of Strep. canis mastitis in a dairy herd is described. Based on results from bacterial culture and ribotyping, a cat with chronic sinusitis was the most likely source of the outbreak. Subsequent cow-to-cow transmission of Strep. canis was facilitated by poor udder health management, including...

  8. Genetic and Antigenic Evidence Supports the Separation of Hepatozoon canis and Hepatozoon americanum at the Species Level

    OpenAIRE

    Baneth, Gad; Barta, John R.; Shkap, Varda; Martin, Donald S.; Macintire, Douglass K.; Vincent-Johnson, Nancy

    2000-01-01

    Recognition of Hepatozoon canis and Hepatozoon americanum as distinct species was supported by the results of Western immunoblotting of canine anti-H. canis and anti-H. americanum sera against H. canis gamonts. Sequence analysis of 368 bases near the 3′ end of the 18S rRNA gene from each species revealed a pairwise difference of 13.59%.

  9. 76 FR 81665 - Endangered and Threatened Wildlife and Plants; Revising the Listing of the Gray Wolf (Canis lupus...

    Science.gov (United States)

    2011-12-28

    ... Wolf (Canis lupus) in the Western Great Lakes; Final rule #0;#0;Federal Register / Vol. 76, No. 249... (Canis lupus) in the Western Great Lakes AGENCY: Fish and Wildlife Service, Interior. ACTION: Final rule... Minnesota population of gray wolves (Canis lupus) to conform to current statutory and policy requirements...

  10. A critical reflection on current control of Toxocara canis in household dogs

    NARCIS (Netherlands)

    Nijsse, E.R.|info:eu-repo/dai/nl/314103198

    2016-01-01

    Toxocara canis is a roundworm that is common worldwide and also in Dutch household dogs. Adult stages of T. canis can be present in the small intestines of dogs where they produce large numbers of eggs that are shed in the environment (patent infection). Because very young dogs and humans can

  11. Recurrent patent infections with Toxocara canis in household dogs older than six months

    NARCIS (Netherlands)

    Nijsse, Rolf; Mughini-Gras, Lapo; Wagenaar, Jaap A.; Ploeger, Harm W.

    2016-01-01

    Background: To reduce environmental contamination with Toxocara canis eggs, the current general advice is to deworm all dogs older than six months on average four times a year. However, only a small proportion of non-juvenile household dogs actually shed T. canis eggs, and some dogs shed eggs

  12. Recurrent patent infections with Toxocara canis in household dogs older than six months : a prospective study

    NARCIS (Netherlands)

    Nijsse, Rolf; Mughini-Gras, Lapo; Wagenaar, Jaap A; Ploeger, Harm W

    2016-01-01

    BACKGROUND: To reduce environmental contamination with Toxocara canis eggs, the current general advice is to deworm all dogs older than six months on average four times a year. However, only a small proportion of non-juvenile household dogs actually shed T. canis eggs, and some dogs shed eggs more

  13. Primers for polymerase chain reaction to detect genomic DNA of Toxocara canis and T. cati.

    Science.gov (United States)

    Wu, Z; Nagano, I; Xu, D; Takahashi, Y

    1997-03-01

    Primers for polymerase chain reaction to amplify genomic DNA of both Toxocara canis and T. cati were constructed by adapting cloning and sequencing random amplified polymorphic DNA. The primers are expected to detect eggs and/or larvae of T. canis and T. cati, both of which are known to cause toxocariasis in humans.

  14. First Case of Canine Infection with Hepatozoon canis (Apicomplexa: Haemogregarinidae) in the Republic of Korea.

    Science.gov (United States)

    Kwon, Seung-Joo; Kim, Yoon-Hee; Oh, Hyun-Hee; Choi, Ul-Soo

    2017-10-01

    This report describes a dog infected with Hepatozoon canis, the first canine infection in the Republic of Korea. A 2-year-old intact male Maltese dog presented with anorexia and depression. Physical examinations revealed mild dehydration and hyperthermia (39.8°C), and blood analysis showed pancytopenia. Diff-Quik staining of blood smear specimens showed the presence of ellipsoidal shaped structures (gamonts of H. canis) within a small number of neutrophils. Real-time PCR analysis using whole blood confirmed infection by H. canis. The clinical condition of the dog improved after symptomatic treatment and administration of doxycycline. Although a molecular epidemiologic survey in Korea showed H. canis infection of dogs, to our knowledge this is the first report of a dog infection in Korea molecularly shown to be H. canis.

  15. Neutropenia associated with osteomyelitis due to Hepatozoon canis infection in a dog.

    Science.gov (United States)

    Shimokawa Miyama, Takako; Umeki, Saori; Baba, Kenji; Sada, Kumiko; Hiraoka, Hiroko; Endo, Yasuyuki; Inokuma, Hisashi; Hisasue, Masaharu; Okuda, Masaru; Mizuno, Takuya

    2011-10-01

    A 4-year-old, intact male Shiba dog was referred to Yamaguchi University Animal Medical Center, Yamaguchi, Japan, for the following complaints: anorexia, lethargy, intermittent fever, gingival bleeding and abdominal purpura. The dog presented with persistent neutropenia. Histopathological examination of a bone marrow sample revealed round to oval structures that resembled Hepatozoon micromerozoites and formed a "wheel-spoke" pattern. Furthermore, mature neutrophils were observed around these structures. PCR and sequencing using bone marrow aspirate confirmed Hepatozoon canis (H. canis) infection. These findings suggest that the neutropenia observed in this case was associated with osteomyelitis due to H. canis infection. This is the first report of neutropenia associated with H. canis infection. H. canis infection can be included in the differential diagnosis in canine cases of neutropenia in areas where the disease is endemic.

  16. Acquisition and transmission of Hepatozoon canis (Apicomplexa: Hepatozoidae) by the tick Amblyomma ovale (Acari: Ixodidae).

    Science.gov (United States)

    Rubini, A S; Paduan, K S; Martins, T F; Labruna, M B; O'Dwyer, L H

    2009-10-14

    The present study aimed to evaluate under controlled conditions the acquisition of Hepatozoon canis by Amblyomma ovale after feeding on infected dogs, and the subsequent induction of infection in uninfected dogs that ingested the experimentally infected ticks. Two H. canis naturally infected dogs were infested with A. ovale adult ticks derived from an uninfected laboratory tick colony. After feeding, two A. ovale females presented H. canis oocysts in the hemolymph at the first and fourth days after removal of ticks from dogs. The oocysts had an average size of 244.34 microm x 255.46 microm. Three uninfected dogs were fed with ticks previously fed on the infected dogs. Only one dog became infected 32 days after oral inoculation, presenting circulating gametocytes, parasitemia less than 1%, and positive PCR confirmed to be H. canis by DNA sequencing. The results obtained indicated A. ovale ticks as potential vector of H. canis in rural areas of Brazil.

  17. Urinary creatinine to serum creatinine ratio and renal failure index in dogs infected with Babesia canis.

    Science.gov (United States)

    Zygner, Wojciech; Gójska-Zygner, Olga; Wesołowska, Agnieszka; Wędrychowicz, Halina

    2013-09-01

    Urinary creatinine to serum creatinine (UCr/SCr) ratio and renal failure index (RFI) are useful indices of renal damage. Both UCr/SCr ratio and RFI are used in differentiation between prerenal azotaemia and acute tubular necrosis. In this work the authors calculated the UCr/SCr ratio and RFI in dogs infected with Babesia canis and the values of these indices in azotaemic dogs infected with the parasite. The results of this study showed significantly lower UCr/SCr ratio in dogs infected with B. canis than in healthy dogs. Moreover, in azotaemic dogs infected with B. canis the UCr/SCr ratio was significantly lower and the RFI was significantly higher than in non-azotaemic dogs infected with B. canis. The calculated correlation between RFI and duration of the disease before diagnosis and treatment was high, positive and statistically significant (r = 0.89, p caused by B. canis in Poland acute tubular necrosis may develop.

  18. Comparative Foraging Efficiency of Two Sympatric Jackals, Silver-Backed Jackals (Canis mesomelas) and Golden Jackals (Canis aureus), in the Ngorongoro Crater, Tanzania

    OpenAIRE

    Temu, S. E.; Nahonyo, C. L.; Moehlman, P. D.

    2016-01-01

    The foraging efficiency of two sympatric species of jackals, silver-backed jackals (Canis mesomelas) and golden jackals (Canis aureus), was studied in the Ngorongoro crater from July 2014 through May 2015. The focal animal observation method was used and individuals of both species were followed as they foraged from morning to evening. Observations of individuals of both jackal species were made from a vehicle using binoculars and a spotting scope. Three major parameters were used for determi...

  19. The Aro 1 mm Survey of the Oxygen-Rich Envelope of Supergiant Star NML Cygnus

    Science.gov (United States)

    Edwards, Jessica L.; Ziurys, L. M.; Woolf, N. J.

    2011-06-01

    Although a number of molecular line surveys of carbon-rich circumstellar envelopes (CSE) have been performed, only one oxygen-rich CSE, that of VY Canis Majoris (VY CMa), has been studied in depth. The Arizona Radio Observatory (ARO) 1 mm survey of VY CMa showed a very different and interesting chemistry dominated by sulfur- and silicon-bearing compounds as well as a number of more exotic species. A similar survey of the oxygen rich star NML Cygnus (NML Cyg) from 215 to 285 GHz is currently under way using the ARO Sub-millimeter Telescope. Initial observations show that this circumstellar envelope appears to be as chemically rich as that of VY CMa. Molecules including 12CO, 13CO, 12CN, 13CN, HCN, HCO+, CS, SO{_2}, SiO and 30SiO have been observed in NML Cyg. Line profiles of this source also suggest that there may be multiple outflows and that the circumstellar envelope is not spherically symmetric. Current results will be presented.

  20. Intraoperative bleeding in dogs from Grenada seroreactive to Anaplasma platys and Ehrlichia canis.

    Science.gov (United States)

    Lanza-Perea, M; Zieger, U; Qurollo, B A; Hegarty, B C; Pultorak, E L; Kumthekar, S; Bruhl-Day, R; Breitschwerdt, E B

    2014-01-01

    Frequent exposure of Grenadian dogs to Rhipicephalus sanguineus results in Anaplasma platys, and Ehrlichia canis seroreactivity. During elective surgeries, substantial intraoperative hemorrhage occurs in some seroreactive dogs. To assess hemostatic parameters and bleeding tendencies as well as prevalence of PCR positivity in apparently healthy A. platys and E. canis seroreactive and seronegative free-roaming dogs from Grenada. Forty-seven elective surgery dogs allocated to 4 groups: Seronegative control (n = 12), A. platys (n = 10), E. canis (n = 14) and A. platys, and E. canis (n = 11) seroreactive. Preoperatively, hemostasis was assessed by platelet count, prothrombin time, activated partial thromboplastin time, and buccal mucosal bleeding time. Intra- and postoperative bleeding scores were subjectively assigned. Blood, spleen, bone marrow, and lymph node aspirates were tested by PCR. Bleeding scores in dogs coseroreactive for A. platys and E. canis were higher (P = .015) than those of seronegative dogs. A. platys DNA was amplified from 7/21 (33%) A. platys seroreactive dogs and from 1 E. canis seroreactive dog; E. canis DNA was amplified from 21/25 (84%) E. canis seroreactive dogs. E. canis DNA was amplified most often from blood, whereas A. platys DNA was amplified most often from bone marrow. Apparently healthy, free-roaming dogs coseropositive for A. platys and E. canis may have increased intraoperative bleeding tendencies despite normal hemostatic parameters. Future investigations should explore the potential for vascular injury as a cause for bleeding in these dogs. Improved tick control is needed for dogs in Grenada. Copyright © 2014 by the American College of Veterinary Internal Medicine.

  1. MLVA and LPS Characteristics of Brucella canis Isolated from Humans and Dogs in Zhejiang, China

    Directory of Open Access Journals (Sweden)

    Dongri Piao

    2017-12-01

    Full Text Available BackgroundBrucella canis is a pathogenic bacterium that causes brucellosis in dogs, and its zoonotic potential has been increasing in recent years. B. canis is a rare source of human brucellosis in China, where Brucella melitensis has been the major pathogen associated with human brucellosis outbreaks. In late 2011, a case of a B. canis infection was detected in a human patient in Zhejiang Province, China. To compare the genotypes between strains of B. canis isolated from the patient and from dogs, a multiple-locus variable-number tandem-repeat analysis (MLVA-16 was performed. In addition, the lipopolysaccharide-synthesis-related genes were analyzed with the B. canis reference strain RM6/66.Results32 B. canis strains were divided into 26 genotypes using MLVA-16 [Hunter-Gaston Diversity Index (HGDI = 0.976]. The HGDI indexes for various loci ranged between 0.000 and 0.865. All four Hangzhou isolates were indistinguishable using panel 1 (genotype 3 and panel 2A (genotype 28. However, these strains were distinctly different from other isolates from Beijing, Jiangsu, Liaoning, and Inner Mongolia at Bruce 09. The emergence of a human B. canis infection was limited to an area. Comparative analysis indicated B. canis from canines and humans have no differences in lipopolysaccharide-synthesis locus.ConclusionThe comprehensive approaches have been used to analyze human and canine B. canis isolates, including molecular epidemiological and LPS genetic characteristics. Further detailed analysis of the whole genomic sequencing will contribute to understanding of the pathogenicity of B. canis in humans.

  2. High throughput pyrosequencing technology for molecular differential detection of Babesia vogeli, Hepatozoon canis, Ehrlichia canis and Anaplasma platys in canine blood samples.

    Science.gov (United States)

    Kaewkong, Worasak; Intapan, Pewpan M; Sanpool, Oranuch; Janwan, Penchom; Thanchomnang, Tongjit; Kongklieng, Amornmas; Tantrawatpan, Chairat; Boonmars, Thidarut; Lulitanond, Viraphong; Taweethavonsawat, Piyanan; Chungpivat, Sudchit; Maleewong, Wanchai

    2014-06-01

    Canine babesiosis, hepatozoonosis, ehrlichiosis, and anaplasmosis are tick-borne diseases caused by different hemopathogens. These diseases are causes of morbidity and mortality in dogs. The classic method for parasite detection and differentiation is based on microscopic observation of blood smears. The limitations of the microscopic method are that its performance requires a specially qualified person with professional competence, and it is ineffective in differentiating closely related species. This study applied PCR amplification with high throughput pyrosequencing for molecular differential detection of the following 4 hemoparasites common to tropical areas in dog blood samples: Babesia vogeli, Hepatozoon canis, Ehrlichia canis, and Anaplasma platys. PCR was initially used to amplify specific target regions of the ribosomal RNA genes of each parasite using 2 primer pairs that included 18S rRNA for protozoa (B. vogeli and H. canis) and 16S rRNA for rickettsia (E. canis and A. platys). Babesia vogeli and H. canis were discriminated using 9 nucleotide positions out of 30 base pairs, whereas E. canis and A. platys were differentiated using 15 nucleotide positions out of 34 base pairs that were determined from regions adjacent to 3' ends of the sequencing primers. This method provides a challenging alternative for a rapid diagnosis and surveillance of these tick-borne diseases in canines. Copyright © 2014 Elsevier GmbH. All rights reserved.

  3. vy flight and Brownian search patterns of a free-ranging predator reflect different prey field characteristics.

    Science.gov (United States)

    Sims, David W; Humphries, Nicolas E; Bradford, Russell W; Bruce, Barry D

    2012-03-01

    1. Search processes play an important role in physical, chemical and biological systems. In animal foraging, the search strategy predators should use to search optimally for prey is an enduring question. Some models demonstrate that when prey is sparsely distributed, an optimal search pattern is a specialised random walk known as a Lévy flight, whereas when prey is abundant, simple Brownian motion is sufficiently efficient. These predictions form part of what has been termed the Lévy flight foraging hypothesis (LFF) which states that as Lévy flights optimise random searches, movements approximated by optimal Lévy flights may have naturally evolved in organisms to enhance encounters with targets (e.g. prey) when knowledge of their locations is incomplete. 2. Whether free-ranging predators exhibit the movement patterns predicted in the LFF hypothesis in response to known prey types and distributions, however, has not been determined. We tested this using vertical and horizontal movement data from electronic tagging of an apex predator, the great white shark Carcharodon carcharias, across widely differing habitats reflecting different prey types. 3. Individual white sharks exhibited movement patterns that predicted well the prey types expected under the LFF hypothesis. Shark movements were best approximated by Brownian motion when hunting near abundant, predictable sources of prey (e.g. seal colonies, fish aggregations), whereas movements approximating truncated Lévy flights were present when searching for sparsely distributed or potentially difficult-to-detect prey in oceanic or shelf environments, respectively. 4. That movement patterns approximated by truncated Lévy flights and Brownian behaviour were present in the predicted prey fields indicates search strategies adopted by white sharks appear to be the most efficient ones for encountering prey in the habitats where such patterns are observed. This suggests that C. carcharias appears capable of exhibiting

  4. Stability in distribution of a stochastic hybrid competitive Lotka–Volterra model with Lévy jumps

    International Nuclear Information System (INIS)

    Zhao, Yu; Yuan, Sanling

    2016-01-01

    Stability in distribution, implying the existence of the invariant probability measure, is an important measure of stochastic hybrid system. However, the effect of Lévy jumps on the stability in distribution is still unclear. In this paper, we consider a n-species competitive Lotka–Volterra model with Lévy jumps under regime-switching. First, we prove the existence of the global positive solution, obtain the upper and lower boundedness. Then, asymptotic stability in distribution as the main result of our paper is derived under some sufficient conditions. Finally, numerical simulations are carried out to support our theoretical results and a brief discussion is given.

  5. Penile lengthening procedure with V-Y advancement flap and an interposing silicone sheath: A novel methodology

    Directory of Open Access Journals (Sweden)

    B V Srinivas

    2012-01-01

    Full Text Available Surgery to augment penile length has become increasingly common. Lack of standardization of this controversial procedure has led to a wide variety of poorly documented surgical techniques, with unconvincing results. The most commonly used technique involves release of the suspensory ligament, with an advancement of an infrapubic skin flap onto the penis via a V-Y plasty. This technique has a major drawback of the possibility of reattachment of the penis to the pubis. We describe a new technique of interposing a silicone sheath along with V-Y advancement flap that overrides this drawback and minimizes the loss of the gained length.

  6. Dynamics of a stochastic delayed SIR epidemic model with vaccination and double diseases driven by Lévy jumps

    Science.gov (United States)

    Liu, Qun; Jiang, Daqing; Shi, Ningzhong; Hayat, Tasawar

    2018-02-01

    In this paper, we study the dynamics of a stochastic delayed SIR epidemic model with vaccination and double diseases which make the research more complex. The environment variability in this paper is characterized by white noise and Lévy noise. We establish sufficient conditions for extinction and persistence in the mean of the two epidemic diseases. It is shown that: (i) time delay and Lévy noise have important effects on the persistence and extinction of epidemic diseases; (ii) two diseases can coexist under certain conditions.

  7. Usefulness of V-Y Advancement Flap for Defects after Skin Tumor Excision

    Directory of Open Access Journals (Sweden)

    Ki Hyun Kwon

    2012-11-01

    Full Text Available BackgroundAfter skin tumor excision on the face, extremities, or trunk, the choice of treatment for a skin defect is highly variable. Many surgeons prefer to use a local flap rather than a skin graft or free flap for small- or moderately-sized circular defects. We have used unilateral or bilateral V-Y advancement flaps, especially on the face. Here we evaluated the functional and aesthetic results of this technique.MethodsAll of the patients were pathologically diagnosed with squamous cell carcinoma (SCC, basal cell carcinoma (BCC, or malignant melanoma or premalignant lesion (Bowen's disease. Thirty-two patients underwent V-Y advancement flap repair (11 unilateral and 21 bilateral from January 2007 to June 2011. We analyzed the patients' age and satisfaction, and location and size of defect. The patients were followed up for 6 months or more.ResultsThere were 22 women and 10 men. The ages ranged from 47 to 93 years with a mean age of 66 years. The causes were SCC in 15 cases, BCC in 13 cases, malignant melanoma in 1 case, Bowen's disease in 2 cases, and another cause in 1 case. The tumor locations were the face in 28 patients, and the scalp, upper limb, and flank each in one patient. All of the flaps survived and the aesthetic results were good. Postoperative recovery was usually rapid, and no complication or tumor recurrence was observed.ConclusionsThe V-Y advancement flap is often used not only for facial circular defects but also for defects of the trunk and extremities. Its advantages are less scarring and superior aesthetic results as compared with other local flap methods, because of less scarification of adjacent tissue and because it is an easy surgical technique.

  8. Demodicosis caused by Demodex canis and Demodex cornei in dogs.

    Science.gov (United States)

    Sivajothi, S; Sudhakara Reddy, B; Rayulu, V C

    2015-12-01

    Two mongrel dogs aged between 7 and 9 months in a same house were presented to the clinics with a history of chronic dermatitis associated with pruritus. Clinical examination revealed presence of primary and secondary skin lesions on the face, around the ears, chin, neck, fore limbs and lateral abdomen. Examination of skin scrapings revealed Demodex cornei (majority) and D. canis (minority) in both the dogs. By using hair pluck examination D. canis were detected and by tape impression smears examination large number of adult short-tail Demodex mites were found. D. cornei was identified by based on the morphological characters including short opisthosoma with blind and round terminal end. Mean length of total body, opisthosoma of both types of the mites were differed statistically significant (P  0.05). Dogs were treated with daily oral ivermectin @ 500 μg/kg/day, external application of amitraz along with supportive therapy. After completion of 45 days of therapy dogs were recovered completely without any side effects.

  9. Memory-Based Quantity Discrimination in Coyotes (Canis latrans

    Directory of Open Access Journals (Sweden)

    Salif Mahamane

    2014-08-01

    Full Text Available Previous research has shown that the ratio between competing quantities of food significantly mediates coyotes‘ (Canis latrans ability to choose the larger of two food options. These previous findings are consistent with predictions made by Weber‘s Law and indicate that coyotes possess quantity discrimination abilities that are similar to other species. Importantly, coyotes‘ discrimination abilities are similar to domestic dogs (Canis lupus familiaris, indicating that quantitative discrimination may remain stable throughout certain species‘ evolution. However, while previously shown in two domestic dogs, it is unknown whether coyotes possess the ability to discriminate visual quantities from memory. Here, we address this question by displaying different ratios of food quantities to 14 coyotes before placing the choices out of sight. The coyotes were then allowed to select one of either non-visible food quantities. Coyotes‘ discrimination of quantity from memory does not follow Weber‘s Law in this particular task. These results suggest that working memory in coyotes may not be adapted to maintain information regarding quantity as well as in domestic dogs. The likelihood of a coyote‘s choosing the large option increased when it was presented with difficult ratios of food options first, before it was later presented with trials using more easily discriminable ratios, and when the large option was placed on one particular side. This suggests that learning or motivation increased across trials when coyotes experienced difficult ratios first, and that location of food may have been more salient in working memory than quantity of food.

  10. Seroprevalence of Toxocara canis infection in tropical Venezuela.

    Science.gov (United States)

    Lynch, N R; Eddy, K; Hodgen, A N; Lopez, R I; Turner, K J

    1988-01-01

    An enzyme-linked immunosorbent assay (ELISA) was used to determine the seroprevalence of Toxocara canis infection in different socio-economic groups of the tropical population of Venezuela. The lack of definitive independent diagnostic criteria for toxocariasis required the establishment of operational upper limits of normality for Toxocara ELISA values, based upon their log-normalized distribution in a presumptive "non-toxocariasis" sub-population. Only 1.8% of urban subjects of medium-high socio-economic level were considered to be clearly positive in Toxocara ELISA, compared to 20.0% of urban slum dwellers, 25.6% rural subsistence farmers and 34.9% Amazon Indians. As the test was performed using excretory-secretory antigen, and under conditions of competitive inhibition by soluble extracts of non-homologous parasites, co-infection by common intestinal helminths, protozoa or other organisms did not give rise to false positive results. However, strong cross-reactivity with Onchocerca volvulus may have influenced the prevalence figure obtained for the Amazon Indians. These results indicate that T. canis is yet another parasite that is widely distributed in economically underprivileged tropical populations.

  11. Error analysis in Fourier methods for option pricing for exponential Lévy processes

    KAUST Repository

    Crocce, Fabian

    2015-01-07

    We derive an error bound for utilising the discrete Fourier transform method for solving Partial Integro-Differential Equations (PIDE) that describe european option prices for exponential Lévy driven asset prices. We give sufficient conditions for the existence of a L? bound that separates the dynamical contribution from that arising from the type of the option n in question. The bound achieved does not rely on information of the asymptotic behaviour of option prices at extreme asset values. In addition, we demonstrate improved numerical performance for select examples of practical relevance when compared to established bounding methods.

  12. Convexity of Ruin Probability and Optimal Dividend Strategies for a General Lévy Process

    Directory of Open Access Journals (Sweden)

    Chuancun Yin

    2015-01-01

    Full Text Available We consider the optimal dividends problem for a company whose cash reserves follow a general Lévy process with certain positive jumps and arbitrary negative jumps. The objective is to find a policy which maximizes the expected discounted dividends until the time of ruin. Under appropriate conditions, we use some recent results in the theory of potential analysis of subordinators to obtain the convexity properties of probability of ruin. We present conditions under which the optimal dividend strategy, among all admissible ones, takes the form of a barrier strategy.

  13. Convexity of Ruin Probability and Optimal Dividend Strategies for a General Lévy Process

    Science.gov (United States)

    Yuen, Kam Chuen; Shen, Ying

    2015-01-01

    We consider the optimal dividends problem for a company whose cash reserves follow a general Lévy process with certain positive jumps and arbitrary negative jumps. The objective is to find a policy which maximizes the expected discounted dividends until the time of ruin. Under appropriate conditions, we use some recent results in the theory of potential analysis of subordinators to obtain the convexity properties of probability of ruin. We present conditions under which the optimal dividend strategy, among all admissible ones, takes the form of a barrier strategy. PMID:26351655

  14. Discretization of Lévy semistationary processes with application to estimation

    DEFF Research Database (Denmark)

    Bennedsen, Mikkel; Lunde, Asger; Pakkanen, Mikko

    Motivated by the construction of the Ito stochastic integral, we consider a step function method to discretize and simulate volatility modulated Lévy semistationary processes. Moreover, we assess the accuracy of the method with a particular focus on integrating kernels with a singularity...... at the origin. Using the simulation method, we study the finite sample properties of some recently developed estimators of realized volatility and associated parametric estimators for Brownian semistationary processes. Although the theoretical properties of these estimators have been established under high...

  15. Prevalence of Demodex canis-positive healthy dogs at trichoscopic examination.

    Science.gov (United States)

    Fondati, Alessandra; De Lucia, Michela; Furiani, Nicla; Monaco, Moira; Ordeix, Laura; Scarampella, Fabia

    2010-04-01

    Demodex canis is thought to be present in small numbers in the skin of most healthy dogs; however, available data on the prevalence of normal dogs harbouring D. canis are scarce. The purpose of this study was to investigate, using microscopic examination of plucked hairs, the prevalence of healthy dogs harbouring D. canis. Seventy-eight clinically healthy dogs with no history of dermatological problems and clinically normal skin and hair coat were included in the study. Five areas (perioral skin 2-3mm from both labial commissures, periungual skin of the third digit of both anterior paws and chin) were examined in each dog. Fifty to sixty hairs were plucked from each skin site and microscopically examined. No D. canis mites were observed and only one adult form of Demodex injai was found in the labial commissure of one dog. Based on these results, the estimated prevalence of healthy dogs harbouring D. canis in clinically normal skin should not exceed the threshold of 5.4%, with 95% confidence level. Considering our and previous findings, we propose that, although small numbers of D. canis might inhabit the skin of normal dogs, the probability of finding these mites in normal dogs is low. Consequently, in most cases, the presence of a D. canis mite in the skin should not be considered as indicative of normality.

  16. SCM-positive Streptococcus canis are predominant among pet-associated group G streptococci.

    Science.gov (United States)

    Verkühlen, Gerd-Josef; Pägelow, Dennis; Valentin-Weigand, Peter; Fulde, Marcus

    2016-01-01

    Streptococcus (S.) canis is a neglected zoonotic pathogen with increasing impor- tance. Since knowledge about its distribution in pets in Germany is scant, we designed a study and tested 335 dogs and 71 cats for colonization by S. canis. S. canis was isolated from swabs taken from the perianal region by culture and subsequent identification was performed biochemically as well as by PCR. In total, 15.8% (53) of the canine and 8.5% (six) of the feline strains grown on Staphlyo- coccus/Streptococcus Selective Agar were tested positive for the Lancefield group G antigen. The vast majority of strains expressing the Lancefield Group G carbohy- drate (56 out of 59) were further identified as S. canis underlining their outstanding role among animal-associated Group G streptococci (GGS). Furthermore, 90.0% of the canine and 83.3% of the feline S. canis strains harbour the species-specific anti- phagocytic M protein homologue SCM, which has been described as an important virulence factor. In contrast, emm-genes typically encoded by human-specific GGS could not be detected in any of the S. canis isolates. Taken together, this study provides insights into the distribution of the neglected zoonotic pathogen S. canis in a population of pets in Germany. The presence of SCM in the vast majority of strains indicates their pathogenic potential.

  17. Molecular detection of Dirofilaria immitis, Hepatozoon canis, Babesia spp., Anaplasma platys and Ehrlichia canis in dogs on Costa Rica.

    Science.gov (United States)

    Wei, Lanjing; Kelly, Patrick; Ackerson, Kate; El-Mahallawy, Heba S; Kaltenboeck, Bernhard; Wang, Chengming

    2014-03-01

    Although vector-borne diseases are important causes of morbidity and mortality in dogs in tropical areas, there is little information on these conditions in Costa Rica. In PCRs of blood from dogs in Costa Rica, we did not detect DNAs of Rickettsia (R.) felis and Coxiella (C.) burnetii but we did find evidence of infection with Dirofilaria (D.) immitis (9/40, 22.5%), Hepatozoon (H.) canis (15/40, 37.5%), Babesia spp. (10/40, 25%; 2 with B. gibsoni and 8 with B. vogeli), Anaplasma (A.) platys (3/40, 7.5%) and Ehrlichia (E.) canis (20/40, 50%). Nine dogs (22.5%) were free of any vector-borne pathogens while 14 (35%) were infected with a single pathogen, 11 (27.5%) with two, 4 (10%) with three, 1 (2.5%) with four, and 1 (2.5%) with five pathogens. Dogs in Costa Rica are commonly infected with vector-borne agents.

  18. Infestivity of Demodex canis to hamster skin engrafted onto SCID mice.

    Science.gov (United States)

    Tani, Kenji; Une, Satoshi; Hasegawa, Atsuhiko; Adachi, Makoto; Kanda, Naoko; Watanabe, Shin-ichi; Nakaichi, Munekazu; Taura, Yasuho

    2005-04-01

    We demonstrated that Demodex canis was transferred to skin xenografts of a dog and a hamster onto severe combined immunodeficiency mice. After the transfer of mites, the number of eggs, larvae, nymphs and adult mites per gram of canine and hamster xenografts increased, whereas no live mites were detected on murine allograft. These results indicate that D. canis proliferates in hair follicles of dog and hamster skins but not in murine allograft. Therefore, D. canis may have host preference but not strict host-specificity.

  19. Asymmetric Lévy flights in the presence of absorbing boundaries

    International Nuclear Information System (INIS)

    De Mulatier, Clélia; Rosso, Alberto; Schehr, Grégory

    2013-01-01

    We consider a one-dimensional asymmetric random walk whose jumps are identical, independent and drawn from a distribution ϕ(η) displaying asymmetric power-law tails (i.e. ϕ(η) ∼ c/η α+1 for large positive jumps and ϕ(η) ∼ c/(γ|η| α+1 ) for large negative jumps, with 0 n , converges to an asymmetric Lévy stable law of stability index α and skewness parameter β = (γ − 1)/(γ + 1). In particular, the right tail of this PDF decays as c n/x n 1+α . Much less is known when the walker is confined, or partially confined, in a region of the space. In this paper we first study the case of a walker constrained to move on the positive semi-axis and absorbed once it changes sign. In this case, the persistence exponent θ + , which characterizes the algebraic large time decay of the survival probability, can be computed exactly and we show that, if θ + + )x n 1+α . This last result can be generalized in higher dimensions such as a two-dimensional random walker performing Lévy stable jumps and confined in a wedge with absorbing walls. Our results are corroborated by precise numerical simulations. (paper)

  20. On the Laws of Total Local Times for -Paths and Bridges of Symmetric Lévy Processes

    Directory of Open Access Journals (Sweden)

    Masafumi Hayashi

    2013-01-01

    Full Text Available The joint law of the total local times at two levels for -paths of symmetric Lévy processes is shown to admit an explicit representation in terms of the laws of the squared Bessel processes of dimensions two and zero. The law of the total local time at a single level for bridges is also discussed.

  1. Optimal harvesting policy of a stochastic two-species competitive model with Lévy noise in a polluted environment

    Science.gov (United States)

    Zhao, Yu; Yuan, Sanling

    2017-07-01

    As well known that the sudden environmental shocks and toxicant can affect the population dynamics of fish species, a mechanistic understanding of how sudden environmental change and toxicant influence the optimal harvesting policy requires development. This paper presents the optimal harvesting of a stochastic two-species competitive model with Lévy noise in a polluted environment, where the Lévy noise is used to describe the sudden climate change. Due to the discontinuity of the Lévy noise, the classical optimal harvesting methods based on the explicit solution of the corresponding Fokker-Planck equation are invalid. The object of this paper is to fill up this gap and establish the optimal harvesting policy. By using of aggregation and ergodic methods, the approximation of the optimal harvesting effort and maximum expectation of sustainable yields are obtained. Numerical simulations are carried out to support these theoretical results. Our analysis shows that the Lévy noise and the mean stress measure of toxicant in organism may affect the optimal harvesting policy significantly.

  2. Efficient Pricing of European-Style Asian Options under Exponential Lévy Processes Based on Fourier Cosine Expansions

    NARCIS (Netherlands)

    Zhang, B.; Oosterlee, C.W.

    2013-01-01

    We propose an efficient pricing method for arithmetic and geometric Asian options under exponential Lévy processes based on Fourier cosine expansions and Clenshaw–Curtis quadrature. The pricing method is developed for both European style and American-style Asian options and for discretely and

  3. Extreme events as foundation of Lévy walks with varying velocity

    Science.gov (United States)

    Kutner, Ryszard

    2002-11-01

    In this work we study the role of extreme events [E.W. Montroll, B.J. West, in: J.L. Lebowitz, E.W. Montrell (Eds.), Fluctuation Phenomena, SSM, vol. VII, North-Holland, Amsterdam, 1979, p. 63; J.-P. Bouchaud, M. Potters, Theory of Financial Risks from Statistical Physics to Risk Management, Cambridge University Press, Cambridge, 2001; D. Sornette, Critical Phenomena in Natural Sciences. Chaos, Fractals, Selforganization and Disorder: Concepts and Tools, Springer, Berlin, 2000] in determining the scaling properties of Lévy walks with varying velocity. This model is an extension of the well-known Lévy walks one [J. Klafter, G. Zumofen, M.F. Shlesinger, in M.F. Shlesinger, G.M. Zaslavsky, U. Frisch (Eds.), Lévy Flights and Related Topics ion Physics, Lecture Notes in Physics, vol. 450, Springer, Berlin, 1995, p. 196; G. Zumofen, J. Klafter, M.F. Shlesinger, in: R. Kutner, A. Pȩkalski, K. Sznajd-Weron (Eds.), Anomalous Diffusion. From Basics to Applications, Lecture Note in Physics, vol. 519, Springer, Berlin, 1999, p. 15] introduced in the context of chaotic dynamics where a fixed value of the walker velocity is assumed for simplicity. Such an extension seems to be necessary when the open and/or complex system is studied. The model of Lévy walks with varying velocity is spanned on two coupled velocity-temporal hierarchies: the first one consisting of velocities and the second of corresponding time intervals which the walker spends between the successive turning points. Both these hierarchical structures are characterized by their own self-similar dimensions. The extreme event, which can appear within a given time interval, is defined as a single random step of the walker having largest length. By finding power-laws which describe the time-dependence of this displacement and its statistics we obtained two independent diffusion exponents, which are related to the above-mentioned dimensions and which characterize the extreme event kinetics. In this work we show the

  4. Results from the Coded Aperture Neutron Imaging System (CANIS)

    International Nuclear Information System (INIS)

    Brubaker, Erik; Steele, John T.; Brennan, James S.; Hilton, Nathan R.; Marleau, Peter

    2010-01-01

    Because of their penetrating power, energetic neutrons and gamma rays (∼1 MeV) offer the best possibility of detecting highly shielded or distant special nuclear material (SNM). Of these, fast neutrons offer the greatest advantage due to their very low and well understood natural background. We are investigating a new approach to fast-neutron imaging- a coded aperture neutron imaging system (CANIS). Coded aperture neutron imaging should offer a highly efficient solution for improved detection speed, range, and sensitivity. We have demonstrated fast neutron and gamma ray imaging with several different configurations of coded masks patterns and detectors including an 'active' mask that is composed of neutron detectors. Here we describe our prototype detector and present some initial results from laboratory tests and demonstrations.

  5. Prolonged intensive dominance behavior between gray wolves, Canis lupus

    Science.gov (United States)

    Mech, L. David; Cluff, H. Dean

    2010-01-01

    Dominance is one of the most pervasive and important behaviors among wolves in a pack, yet its significance in free-ranging packs has been little studied. Insights into a behavior can often be gained by examining unusual examples of it. In the High Arctic near Eureka, Nunavut, Canada, we videotaped and described an unusually prolonged and intensive behavioral bout between an adult male Gray Wolf (Canis lupus) and a male member of his pack, thought to be a maturing son. With tail raised, the adult approached a male pack mate about 50 m from us and pinned and straddled this packmate repeatedly over 6.5 minutes, longer than we had ever seen in over 50 years of studying wolves. We interpreted this behavior as an extreme example of an adult wolf harassing a maturing offspring, perhaps in prelude to the offspring?s dispersal.

  6. [Diphyllobothrium pacificum (Nybelin,1931) margolis, 1956 in Canis familiaris from Chincha city, Peru].

    Science.gov (United States)

    Cabrera, R; Tantaleán, M; Rojas, R

    2001-01-01

    In this communication is presented the finding of the tapeworm Diphyllobothrium pacificum, parasite of sea lions, in Canis familiaris (dog) in Chincha city, Peru. This is the first canine infection with D. pacificum in the South Peruvian coast.

  7. Prevalence of Toxoplasma gondii and Toxocara canis among Patients with Uveitis.

    Science.gov (United States)

    Lim, Su Jin; Lee, Sang Eun; Kim, Sun Hyun; Hong, Sung-Hee; You, Yong Sung; Kwon, Oh Woong; Kim, Hyeun Seung

    2015-04-01

    To investigate the prevalence of Toxoplasma gondii and Toxocara canis in patients with uveitis. Patients with uveitis were examined. Serum antibodies to T. gondii and T. canis were tested by using the enzyme-linked immunosorbent assay. Polymerase chain reaction (PCR) was done using blood and aqueous humor (AH). Ninety-eight patients were enrolled. Mean age was 43.5 ± 13.2 years. Six patients were seropositive for T. gondii with the following pattern: anterior uveitis, 1; posterior uveitis with retinitis, 2; pan uveitis, 2. One patient had a positive PCR result for T. gondii in AH, who showed panuveitis. Twenty-three patients were positive to serum IgG for T. canis with the following clinical manifestation: granuloma, 6; pigmented scar, 3; vitritis, 6--but none were PCR positive. T. gondii and T. canis are still important causes of uveitis. Ocular toxocariasis is not an uncommon cause of uveitis, even in adults.

  8. First isolation and molecular characterization of Ehrlichia canis in Costa Rica, Central America.

    Science.gov (United States)

    Romero, L E; Meneses, A I; Salazar, L; Jiménez, M; Romero, J J; Aguiar, D M; Labruna, M B; Dolz, G

    2011-08-01

    The present study investigated Ehrlichia species in blood samples from dogs suspected of clinical ehrlichiosis, using molecular and isolation techniques in cell culture. From a total of 310 canine blood samples analyzed by 16S rRNA nested PCR, 148 (47.7%) were positive for Ehrlichia canis. DNA from Ehrlichia chaffeensis or Ehrlichia ewingii was not detected in any sample using species-specific primers in separated reactions. Leukocytes from five PCR-positive dogs were inoculated into DH82 cells; successful isolation of E. canis was obtained in four samples. Partial sequence of the dsb gene of eight canine blood samples (including the five samples for in vitro isolation) was obtained by PCR and their analyses through BLAST showed 100% of identity with the corresponding sequence of E. canis in GenBank. This study represents the first molecular diagnosis, isolation, and molecular characterization of E. canis in dogs from Costa Rica. Copyright © 2010 Elsevier Ltd. All rights reserved.

  9. Spatial distribution of Anaplasma phagocytophilum and Hepatozoon canis in red foxes (Vulpes vulpes) in Hungary.

    Science.gov (United States)

    Tolnai, Z; Sréter-Lancz, Z; Sréter, T

    2015-07-01

    In recent years, Ehrlichia canis and Hepatozoon canis transmitted by Rhipicephalus sanguineus were reported from Hungary. The aim of the present study was to reveal the spatial distribution pattern of pathogens transmitted by R. sanguineus in a sentinel species, red fox (Vulpes vulpes) in Hungary and to analyse the relationship of these patterns with landscape and climate by geographical information systems. Fox carcasses, representing 0.5% of the total fox population were randomly selected out of all the foxes of Hungary. The spleen samples of the animals were tested by real-time PCR for Anaplasma platys, Babesia vogeli, E. canis and H. canis infection. Positive results were confirmed by conventional PCR followed by sequencing. The prevalence of H. canis infection was 22.2% (95% CI=18.4-26.4%), and this parasite was detected in all areas including the mountain regions of Hungary. These findings indicate that other tick species or other transmission routes (oral and transplacental) might be in the background of the countrywide distribution of H. canis. Anaplasma platys was not found; nevertheless, the prevalence of Anaplasma phagocytophilum infection transmitted by Ixodes ricinus was 12.5% (95% CI=9.7-16.1%) in foxes. B. vogeli and E. canis infection was not detected. There was no correlation between environmental parameter values in the home range of foxes and A. phagocytophilum or H. canis infection, which is in line with that observed in the case of tick species infesting foxes in Hungary. The results of this study indicate that R. sanguineus, if present, might be rare in Hungary. Our baseline study can be used for future evaluation of the effect of climate change on the spreading and emergence of R. sanguineus transmitted pathogens in Hungary. Copyright © 2015 Elsevier GmbH. All rights reserved.

  10. Transstadial Transmission of Hepatozoon canis by Rhipicephalus sanguineus (Acari: Ixodidae) in Field Conditions.

    Science.gov (United States)

    Aktas, M; Özübek, S

    2017-07-01

    This study investigated possible transovarial and transstadial transmission of Hepatozoon canis by Rhipicephalus sanguineus (Latreille) ticks collected from naturally infected dogs in a municipal dog shelter and the grounds of the shelter. Four hundred sixty-five engorged nymphs were collected from 16 stray dogs that were found to be infected with H. canis by blood smear and PCR analyses and maintained in an incubator at 28 °C for moulting. Four hundred eighteen nymphs moulted to adults 14-16 d post collection. Unfed ticks from the shelter grounds comprised 1,500 larvae, 2,100 nymphs, and 85 adults; were sorted according to origin, developmental stage, and sex into 117 pools; and screened by 18S rRNA PCR for Hepatozoon infection. Of 60 adult tick pools examined, 51 were infected with H. canis. The overall maximum likelihood estimate (MLE) of infection rate was calculated as 21.0% (CI 15.80-28.21). Hepatozoon canis was detected in 31 out of 33 female pools (MLE 26.96%, CI 17.64-44.33) and 20 out of 27 male pools (MLE 14.82%, CI 20.15-46.41). Among 42 unfed nymph pools collected from the shelter, 26 were infected with H. canis, and MLE of infection was calculated as 1.9% (CI 1.25-2.77). No H. canis DNA was detected in any of the gDNA pools consisting of larva specimens. Partial sequences of the 18S rRNA gene shared 99-100% similarity with the corresponding H. canis isolates. Our results revealed the transstadial transmission of H. canis by R. sanguineus, both from larva to nymph and from nymph to adult, in field conditions. However, there were no evidence of transovarial transmission. © The Authors 2017. Published by Oxford University Press on behalf of Entomological Society of America. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  11. [Characterization of the genetic variability of field strains of Brucella canis isolated in Antioquia].

    Science.gov (United States)

    Vidal Arboleda, Juana L; Ortiz Roman, Luisa F; Olivera Angel, Martha

    2017-12-22

    Brucella canis is a facultative intracellular pathogen responsible for canine brucellosis, a zoonotic disease that affects canines, causing abortions and reproductive failure; and the production of non-specific symptoms in humans. In 2005 the presence of B. canis in Antioquia was demonstrated and the strains were identified as type 2. The sequencing of the genome of a field strain denoted Brucella canis str. Oliveri, showed species-specific indel events, which led us to investigate the genomic characteristics of the B. canis strain isolated and to establish the phylogenetic relationships and the divergence time of B. canis str. Oliveri. Conventional PCR sequencing was performed in 30 field strains identifying 5 indel events recognized in B. canis str. Oliveri. ADN from Brucella suis, Brucella melitensis and vaccine strains from Brucella abortus were used as control, and it was determined that all of the studied field strains shared 4 out of the 5 indels of the sequenced Oliveri strain, indicating the presence of more than one strain circulating in the region. Phylogenetic analysis was performed with 24 strains of Brucella using concatenated sequences of genetic markers for species differentiation. The molecular clock hypothesis and Tajima's relative rate test were tested, showing that the Oliveri strain, similarly to other canis species, diverged from B. suis. The molecular clock hypothesis between Brucella species was rejected and an evolution rate and a similar genetic distance between the B. canis were demonstrated. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  12. Behavioral changes in Rattus norvegicus coinfected by Toxocara canis and Toxoplasma gondii

    Directory of Open Access Journals (Sweden)

    Maisa Leite de Queiroz

    2013-02-01

    Full Text Available Using an elevated plus maze apparatus and an activity cage, behavioral changes in Rattus norvegicus concomitantly infected by Toxocara canis and Toxoplasma gondii were studied, during a period of 120 days. Rats infected by Toxocara canis or Toxoplasma gondii showed significant behavioral changes; however, in the group coinfected by both parasites a behavioral pattern similar to that found in the group not infected was observed thirty days after infection, suggesting the occurrence of modulation in the behavioral response.

  13. Transstadial transmission of Hepatozoon canis from larvae to nymphs of Rhipicephalus sanguineus.

    Science.gov (United States)

    Giannelli, Alessio; Ramos, Rafael Antonio Nascimento; Di Paola, Giancarlo; Mencke, Norbert; Dantas-Torres, Filipe; Baneth, Gad; Otranto, Domenico

    2013-09-01

    Hepatozoon canis is an apicomplexan parasite of dogs, which is known to become infected by ingesting Rhipicephalus sanguineus adult ticks. To investigate the possibility of H. canis transovarial and transstadial transmission from larvae to nymphs, engorged adult female ticks were collected from a private animal shelter in southern Italy, where H. canis infection is highly prevalent. Female ticks (n=35) and egg batches were tested by PCR for H. canis. All eggs examined were PCR-negative whereas 88.6% of females from the environment tested positive. Additionally, fed larvae (n=120) from a dog naturally infected by H. canis were dissected at different time points post collection (i.e. 0, 10, 20 and 30 days). Molted nymphs dissected at 20 days post collection revealed immature oocysts displaying an amorphous central structure in 50% of the specimens, and oocysts containing sporocysts with sporozoites were found in 53.3% of the nymphs dissected at 30 days post collection. This study demonstrates that H. canis is not transmitted transovarially, but it is transmitted transstadially from larvae to nymphs of R. sanguineus and develops sporozoites in oocysts that may infect dogs. Copyright © 2013 Elsevier B.V. All rights reserved.

  14. Novel genotype of Ehrlichia canis detected in samples of human blood bank donors in Costa Rica.

    Science.gov (United States)

    Bouza-Mora, Laura; Dolz, Gaby; Solórzano-Morales, Antony; Romero-Zuñiga, Juan José; Salazar-Sánchez, Lizbeth; Labruna, Marcelo B; Aguiar, Daniel M

    2017-01-01

    This study focuses on the detection and identification of DNA and antibodies to Ehrlichia spp. in samples of blood bank donors in Costa Rica using molecular and serological techniques. Presence of Ehrlichia canis was determined in 10 (3.6%) out of 280 blood samples using polymerase chain reaction (PCR) targeting the ehrlichial dsb conserved gene. Analysis of the ehrlichial trp36 polymorphic gene in these 10 samples revealed substantial polymorphism among the E. canis genotypes, including divergent tandem repeat sequences. Nucleotide sequences of dsb and trp36 amplicons revealed a novel genotype of E. canis in blood bank donors from Costa Rica. Indirect immunofluorescence assay (IFA) detected antibodies in 35 (35%) of 100 serum samples evaluated. Thirty samples showed low endpoint titers (64-256) to E. canis, whereas five sera yielded high endpoint titers (1024-8192); these five samples were also E. canis-PCR positive. These findings represent the first report of the presence of E. canis in humans in Central America. Copyright © 2016 Elsevier GmbH. All rights reserved.

  15. The Publicly Available Prebiotic Interstellar Molecular Survey (primos): Expanding Spectroscopic Characterizations, Extending to New Sources, and Adding to the Known Molecular Inventory

    Science.gov (United States)

    McGuire, Brett A.; Carroll, P. Brandon; Corby, Joanna F.; Loomis, Ryan A.; Blake, Geoffrey A.; Hollis, Jan M.; Lovas, Frank J.; Jewell, Philip R.; Remijan, Anthony J.

    2013-06-01

    The publicly available Green Bank Telescope PRebiotic Interstellar MOlecular Survey (PRIMOS) conducted towards Sgr B2(N) provides high resolution, high-sensitivity observations with near-continuous frequency coverage from ˜300 MHz - 50 GHz. Of the eleven new molecular detections in the last year, five (45%) are a direct result of the PRIMOS observations. Further, these observations have recently been used to detect the predicted, but previously unobserved, J = 1-0 and J=2-1 transitions of the newly detected l-C_3H^+ ion. Here, we discuss the analysis of these transitions, as well as recent work to extend the PRIMOS observations to three new regions of interest: VY Canis Majoris, IRC+10216, and NGC 2023. Finally, we highlight the utility of cm-wave surveys in new molecular detections, as well as the value of publicly-available surveys in the approaching era of data-enabled, analysis-limited astrochemistry.

  16. A Millimeter Polarimeter for the 45-m Telescope at Nobeyama

    Science.gov (United States)

    Shinnaga, Hiroko; Tsuboi, Masato; Kasuga, Takashi

    1999-04-01

    We have designed and constructed a tunable polarimeter to cover frequencies from 35 GHz to 250 GHz (8.6 mm and 1.2 mm in wavelength) for the 45-m telescope at Nobeyama Radio Observatory. Both circular and linear polarizations can be measured by the polarimeter. The insertion loss was measured to be 0.14 +/- 0.05 dB in the 100-GHz band. The overall instrumental polarization of the system in the 100 GHz band is as low as VY Canis Majoris. The observation revealed that the J = 2--1 emission in the v = 0 state of the object is highly linear polarized, which suggests that the emission originates through maser action in the circumstellar region. The details of the design, construction, and tests are presented. Nobeyama Radio Observatory is a branch of the National Astronomical Observatory, operated by the Ministry of Education, Science, Sports and Culture.

  17. Phosphorus Chemistry in Oxygen Rich Stars

    Science.gov (United States)

    Bernal, Jacob; Schmidt, Deborah; Anderson, Julie; Ziurys, Lucy M.

    2017-06-01

    Observations of PO and PN have been carried out at the Arizona Radio Observatory at 1, 2, and 3 mm. Multiple transitions of PO and PN have been detected towards the O-rich AGB stars TX Cam and RCas. Data obtained toward supergiant stars VY Canis Majoris and NML Cyg have also been analyzed. Abundances were obtained for these molecules in all four objects using the radiative transfer code ESCAPADE, which is suitable for symmetric and asymmetric stellar outflows. The abundances of PN and PO were found to be in the range 10^{-8} - 10^{-7} relative to H_{2}. While PN appears to be a parent molecule formed by LTE chemistry near the stellar photosphere, PO appears to be created further out from the star at r > 400 R_*.

  18. Size‐assortative choice and mate availability influences hybridization between red wolves (Canis rufus) and coyotes (Canis latrans)

    Science.gov (United States)

    Hinton, Joseph W.; Gittleman, John L.; van Manen, Frank T.; Chamberlain, Michael J.

    2018-01-01

    Anthropogenic hybridization of historically isolated taxa has become a primary conservation challenge for many imperiled species. Indeed, hybridization between red wolves (Canis rufus) and coyotes (Canis latrans) poses a significant challenge to red wolf recovery. We considered seven hypotheses to assess factors influencing hybridization between red wolves and coyotes via pair‐bonding between the two species. Because long‐term monogamy and defense of all‐purpose territories are core characteristics of both species, mate choice has long‐term consequences. Therefore, red wolves may choose similar‐sized mates to acquire partners that behave similarly to themselves in the use of space and diet. We observed multiple factors influencing breeding pair formation by red wolves and found that most wolves paired with similar‐sized conspecifics and wolves that formed congeneric pairs with nonwolves (coyotes and hybrids) were mostly female wolves, the smaller of the two sexes. Additionally, we observed that lower red wolf abundance relative to nonwolves and the absence of helpers increased the probability that wolves consorted with nonwolves. However, successful pairings between red wolves and nonwolves were associated with wolves that maintained small home ranges. Behaviors associated with territoriality are energetically demanding and behaviors (e.g., aggressive interactions, foraging, and space use) involved in maintaining territories are influenced by body size. Consequently, we propose the hypothesis that size disparities between consorting red wolves and coyotes influence positive assortative mating and may represent a reproductive barrier between the two species. We offer that it may be possible to maintain wild populations of red wolves in the presence of coyotes if management strategies increase red wolf abundance on the landscape by mitigating key threats, such as human‐caused mortality and hybridization with coyotes. Increasing red wolf abundance would

  19. Plány Vyšehradu v Národní knihovně v Paříži

    Czech Academy of Sciences Publication Activity Database

    Nechvátal, Bořivoj

    2016-01-01

    Roč. 41, č. 2 (2016), s. 229-242 ISSN 0231-5823 Institutional support: RVO:67985912 Keywords : defence system * palisades * bastion * ravelin * Vyšehrad Subject RIV: AC - Archeology, Anthropology, Ethnology

  20. Brucella canis: inquéritos sorológico e bacteriológico em população felina Brucella canis: serological and bacteriological surveys in the feline population

    Directory of Open Access Journals (Sweden)

    Maria Helena Matiko Akao Larsson

    1984-02-01

    Full Text Available De 134 soros de felinos domésticos examinados pela prova de soroaglutinação lenta em tubos, 4 (3% foram positivos para Brucella canis, todos com título igual a 100. Não se obteve êxito na tentativa de isolamento de Brucella canis através de hemocultura desses animais.Of the 134 feline sera tested by tube agglutination test, 4 (3% were positive for Brucella canis antibodies, all with titer 100. It was not possible to isolate Brucella canis by blood culture in the case of these animals.

  1. Hepatozoon canis (James, 1905 in dogs from Uberlândia, Minas Gerais. Reports of two cases.

    Directory of Open Access Journals (Sweden)

    Antonio Vicente Mundim

    1992-12-01

    Full Text Available Hepatozoon canis gametocytes, measuring 9,56 µm x 5,60 µm were identified in circulating leukocytes of two dogs admitted to the Veterinary Hospital of the Universidade Federal de Uberlândia. Morulae of Ehrlichia canis were also found in circulating monocytes. The authors report the first occurrence of H. canis in Uberlândia, Minas Gerais state.

  2. Genetic and Antigenic Evidence Supports the Separation of Hepatozoon canis and Hepatozoon americanum at the Species Level

    Science.gov (United States)

    Baneth, Gad; Barta, John R.; Shkap, Varda; Martin, Donald S.; Macintire, Douglass K.; Vincent-Johnson, Nancy

    2000-01-01

    Recognition of Hepatozoon canis and Hepatozoon americanum as distinct species was supported by the results of Western immunoblotting of canine anti-H. canis and anti-H. americanum sera against H. canis gamonts. Sequence analysis of 368 bases near the 3′ end of the 18S rRNA gene from each species revealed a pairwise difference of 13.59%. PMID:10699047

  3. Efficacy of Zingiber officinale ethanol extract on the viability, embryogenesis and infectivity of Toxocara canis eggs.

    Science.gov (United States)

    El-Sayed, Nagwa Mostafa

    2017-12-01

    This study evaluated the effect of Zingiber officinal e ( Z. officinal e) ethanol extract on the viability, embryogenesis and infectivity Toxocara canis ( T. canis ) eggs. It was carried out both in vitro and in vivo. In the in vitro experiment, unembryonated T. canis eggs were incubated with 25, 50 and 100 mg/mL Z. officinal e extract at 25 °C for 6, 12, and 24 h to assess the effect of Z. officinal e on their viability and for two weeks to assess the effect of Z. officinal e on their embryogenesis. In vivo experiment was performed to assess the effect of Z. officinal e on infectivity of T. canis eggs. Treated embryonated eggs by Z. officinale extract at concentrations of 25, 50 and 100 mg/mL for 24 h were inoculated into mice and their livers were examined for the presence of T. canis larvae on the 7th day after infection and for histopathological evaluation at 14th day post-infection. Z. officinal e showed a significant ovicidal activity on T. canis eggs. The best effect was observed with 100 mg/mL concentration after 24 h with an efficacy of 98.2%. However, the treated eggs by 25, 50 mg/mL of Z. officinale extract after 24 h showed ovicidal activity by 59.22 and 82.5% respectively. Moreover, this extract effectively inhibited T. canis eggs embryogenesis by 99.64% and caused their degeneration at the concentration of 100 mg/mL after 2 weeks of treatment. However, the lower concentrations, 25 and 50 mg/mL inhibited embryogenesis by 51.19 and 78.57% respectively. The effect of Z. officinal e on the infectivity T. canis eggs was proven by the reduction of larvae recovery in the livers by 35.9, 62.8 and 89.5% in mice groups inoculated by Z. officinale treated eggs at concentrations of 25, 50 and 100 mg/mL respectively. Histopathologically, the liver tissues of mice infected with Z. officinale treated eggs at the concentration of 100 mg/mL appeared healthy with slight degenerative changes of hepatocytes, opposite to that recorded in the infected mice

  4. Diagnosis of Hepatozoon canis in young dogs by cytology and PCR

    Directory of Open Access Journals (Sweden)

    Decaprariis Donato

    2011-04-01

    Full Text Available Abstract Background Hepatozoon canis is a widespread tick-borne protozoan affecting dogs. The diagnosis of H. canis infection is usually performed by cytology of blood or buffy coat smears, but this method may not be sensitive. Our study aimed to evaluate the best method to achieve a parasitological diagnosis of H. canis infection in a population of receptive young dogs, previously negative by cytology and exposed to tick infestation for one summer season. Results A total of 73 mongrel dogs and ten beagles younger than 18 months of age, living in an animal shelter in southern Italy where dogs are highly infested by Rhipicephalus sanguineus, were included in this study. In March-April 2009 and in October 2009, blood and bone marrow were sampled from each dog. Blood, buffy coat and bone marrow were examined by cytology only (at the first sampling and also by PCR for H. canis (second sampling. In March-April 2009, only one dog was positive for H. canis by cytological examination, whereas in October 2009 (after the summer season, the overall incidence of H. canis infection by cytological examinations was 43.9%. Molecular tests carried out on samples taken in October 2009 showed a considerably higher number of dogs positive by PCR (from 27.7% up to 51.2% on skin and buffy coat tissues, respectively, with an overall positivity of 57.8%. All animals, but one, which were positive by cytology were also PCR-positive. PCR on blood or buffy coat detected the highest number of H. canis-positive dogs displaying a sensitivity of 85.7% for both tissues that increased up to 98% when used in parallel. Twenty-six (74.8% out of the 28 H. canis-positive dogs presented hematological abnormalities, eosinophilia being the commonest alteration observed. Conclusions The results suggest that PCR on buffy coat and blood is the best diagnostic assay for detecting H. canis infection in dogs, although when PCR is not available, cytology on buffy coat should be preferred to

  5. Diagnosis of Hepatozoon canis in young dogs by cytology and PCR

    Science.gov (United States)

    2011-01-01

    Background Hepatozoon canis is a widespread tick-borne protozoan affecting dogs. The diagnosis of H. canis infection is usually performed by cytology of blood or buffy coat smears, but this method may not be sensitive. Our study aimed to evaluate the best method to achieve a parasitological diagnosis of H. canis infection in a population of receptive young dogs, previously negative by cytology and exposed to tick infestation for one summer season. Results A total of 73 mongrel dogs and ten beagles younger than 18 months of age, living in an animal shelter in southern Italy where dogs are highly infested by Rhipicephalus sanguineus, were included in this study. In March-April 2009 and in October 2009, blood and bone marrow were sampled from each dog. Blood, buffy coat and bone marrow were examined by cytology only (at the first sampling) and also by PCR for H. canis (second sampling). In March-April 2009, only one dog was positive for H. canis by cytological examination, whereas in October 2009 (after the summer season), the overall incidence of H. canis infection by cytological examinations was 43.9%. Molecular tests carried out on samples taken in October 2009 showed a considerably higher number of dogs positive by PCR (from 27.7% up to 51.2% on skin and buffy coat tissues, respectively), with an overall positivity of 57.8%. All animals, but one, which were positive by cytology were also PCR-positive. PCR on blood or buffy coat detected the highest number of H. canis-positive dogs displaying a sensitivity of 85.7% for both tissues that increased up to 98% when used in parallel. Twenty-six (74.8%) out of the 28 H. canis-positive dogs presented hematological abnormalities, eosinophilia being the commonest alteration observed. Conclusions The results suggest that PCR on buffy coat and blood is the best diagnostic assay for detecting H. canis infection in dogs, although when PCR is not available, cytology on buffy coat should be preferred to blood smear evaluation

  6. A new PCR assay for the detection and differentiation of Babesia canis and Babesia vogeli.

    Science.gov (United States)

    Annoscia, Giada; Latrofa, Maria Stefania; Cantacessi, Cinzia; Olivieri, Emanuela; Manfredi, Maria Teresa; Dantas-Torres, Filipe; Otranto, Domenico

    2017-10-01

    Babesia spp. are globally distributed tick-borne protozoan parasites that infect the red blood cells of a wide range of vertebrate hosts, including humans. Diagnosis of babesiosis is often impeded by the transient presence of the parasites in peripheral blood, as well as by their pleomorphic nature. Given the reports of an expanding and, in some cases, sympatric geographical distribution of Babesia canis and Babesia vogeli in dogs and associated vectors, in Europe, the development of time-efficient and cost-effective diagnostic tools to detect and differentiate these two species is warranted. In this study, we designed and developed a novel polymerase chain reaction (PCR) assay targeting the parasite cytochrome c oxidase subunit 1 (cox1) gene, for the simultaneous detection and differentiation of B. canis and B. vogeli. The analytical sensitivity of the PCR was evaluated using serial dilutions of genomic DNA extracted from individual and artificially mixed canine blood samples infected by B. canis (3×10 2 infected erythrocytes/ml, ie/ml) and B. vogeli (2.1×10 1 ie/ml). The analytical specificity of the assay was assessed using blood samples positive for Hepatozoon canis, Ehrlichia canis, Anaplasma platys, Babesia microti, Babesia rossi and Theileria annae (syn. Babesia vulpes). The clinical specificity of the PCR assay was evaluated on 147 blood samples from dogs and 128 tick specimens (Dermacentor reticulatus and Rhipicephalus sanguineus sensu lato). Species-specific bands of the expected sizes (i.e., 750bp for B. canis and 450bp for B. vogeli), and two bands in the mixed blood samples were obtained. The PCR assay developed herein detected a low number of infected erythrocytes (i.e., 3×10 -2 B. canis, 2.1×10 -2 B. vogeli ie/ml). Of the 147 blood samples, nine (6.1%) were positive for B. canis and six (4.1%) for B. vogeli, whereas only one tick (D. reticulatus) was positive for B. canis. This PCR assay represents a rapid and reliable tool for the diagnosis of B

  7. Diagnosis of Hepatozoon canis in young dogs by cytology and PCR.

    Science.gov (United States)

    Otranto, Domenico; Dantas-Torres, Filipe; Weigl, Stefania; Latrofa, Maria Stefania; Stanneck, Dorothee; Decaprariis, Donato; Capelli, Gioia; Baneth, Gad

    2011-04-13

    Hepatozoon canis is a widespread tick-borne protozoan affecting dogs. The diagnosis of H. canis infection is usually performed by cytology of blood or buffy coat smears, but this method may not be sensitive. Our study aimed to evaluate the best method to achieve a parasitological diagnosis of H. canis infection in a population of receptive young dogs, previously negative by cytology and exposed to tick infestation for one summer season. A total of 73 mongrel dogs and ten beagles younger than 18 months of age, living in an animal shelter in southern Italy where dogs are highly infested by Rhipicephalus sanguineus, were included in this study. In March-April 2009 and in October 2009, blood and bone marrow were sampled from each dog. Blood, buffy coat and bone marrow were examined by cytology only (at the first sampling) and also by PCR for H. canis (second sampling). In March-April 2009, only one dog was positive for H. canis by cytological examination, whereas in October 2009 (after the summer season), the overall incidence of H. canis infection by cytological examinations was 43.9%. Molecular tests carried out on samples taken in October 2009 showed a considerably higher number of dogs positive by PCR (from 27.7% up to 51.2% on skin and buffy coat tissues, respectively), with an overall positivity of 57.8%. All animals, but one, which were positive by cytology were also PCR-positive. PCR on blood or buffy coat detected the highest number of H. canis-positive dogs displaying a sensitivity of 85.7% for both tissues that increased up to 98% when used in parallel. Twenty-six (74.8%) out of the 28 H. canis-positive dogs presented hematological abnormalities, eosinophilia being the commonest alteration observed. The results suggest that PCR on buffy coat and blood is the best diagnostic assay for detecting H. canis infection in dogs, although when PCR is not available, cytology on buffy coat should be preferred to blood smear evaluation. This study has also demonstrated

  8. Contraction Options and Optimal Multiple-Stopping in Spectrally Negative Lévy Models

    Energy Technology Data Exchange (ETDEWEB)

    Yamazaki, Kazutoshi, E-mail: kyamazak@kansai-u.ac.jp [Kansai University, Department of Mathematics, Faculty of Engineering Science (Japan)

    2015-08-15

    This paper studies the optimal multiple-stopping problem arising in the context of the timing option to withdraw from a project in stages. The profits are driven by a general spectrally negative Lévy process. This allows the model to incorporate sudden declines of the project values, generalizing greatly the classical geometric Brownian motion model. We solve the one-stage case as well as the extension to the multiple-stage case. The optimal stopping times are of threshold-type and the value function admits an expression in terms of the scale function. A series of numerical experiments are conducted to verify the optimality and to evaluate the efficiency of the algorithm.

  9. vy flights in an infinite potential well as a hypersingular Fredholm problem.

    Science.gov (United States)

    Kirichenko, Elena V; Garbaczewski, Piotr; Stephanovich, Vladimir; Żaba, Mariusz

    2016-05-01

    We study Lévy flights with arbitrary index 0potential well of infinite depth. Such a problem appears in many physical systems ranging from stochastic interfaces to fracture dynamics and multifractality in disordered quantum systems. The major technical tool is a transformation of the eigenvalue problem for initial fractional Schrödinger equation into that for Fredholm integral equation with hypersingular kernel. The latter equation is then solved by means of expansion over the complete set of orthogonal functions in the domain D, reducing the problem to the spectrum of a matrix of infinite dimensions. The eigenvalues and eigenfunctions are then obtained numerically with some analytical results regarding the structure of the spectrum.

  10. Contraction Options and Optimal Multiple-Stopping in Spectrally Negative Lévy Models

    International Nuclear Information System (INIS)

    Yamazaki, Kazutoshi

    2015-01-01

    This paper studies the optimal multiple-stopping problem arising in the context of the timing option to withdraw from a project in stages. The profits are driven by a general spectrally negative Lévy process. This allows the model to incorporate sudden declines of the project values, generalizing greatly the classical geometric Brownian motion model. We solve the one-stage case as well as the extension to the multiple-stage case. The optimal stopping times are of threshold-type and the value function admits an expression in terms of the scale function. A series of numerical experiments are conducted to verify the optimality and to evaluate the efficiency of the algorithm

  11. Risk finance for catastrophe losses with Pareto-calibrated Lévy-stable severities.

    Science.gov (United States)

    Powers, Michael R; Powers, Thomas Y; Gao, Siwei

    2012-11-01

    For catastrophe losses, the conventional risk finance paradigm of enterprise risk management identifies transfer, as opposed to pooling or avoidance, as the preferred solution. However, this analysis does not necessarily account for differences between light- and heavy-tailed characteristics of loss portfolios. Of particular concern are the decreasing benefits of diversification (through pooling) as the tails of severity distributions become heavier. In the present article, we study a loss portfolio characterized by nonstochastic frequency and a class of Lévy-stable severity distributions calibrated to match the parameters of the Pareto II distribution. We then propose a conservative risk finance paradigm that can be used to prepare the firm for worst-case scenarios with regard to both (1) the firm's intrinsic sensitivity to risk and (2) the heaviness of the severity's tail. © 2012 Society for Risk Analysis.

  12. Modeling anomalous diffusion by a subordinated fractional Lévy-stable process

    International Nuclear Information System (INIS)

    Teuerle, Marek; Wyłomańska, Agnieszka; Sikora, Grzegorz

    2013-01-01

    Two phenomena that can be discovered in systems with anomalous diffusion are long-range dependence and trapping events. The first effect concerns events that are arbitrarily distant but still influence each other exceptionally strongly, which is characteristic for anomalous regimes. The second corresponds to the presence of constant values of the underlying process. Motivated by the relatively poor class of models that can cover these two phenomena, we introduce subordinated fractional Lévy-stable motion with tempered stable waiting times. We present in detail its main properties, propose a simulation scheme and give an estimation procedure for its parameters. The last part of the paper is a presentation, via the Monte Carlo approach, of the effectiveness of the estimation of the parameters. (paper)

  13. Non-Gaussian power grid frequency fluctuations characterized by Lévy-stable laws and superstatistics

    Science.gov (United States)

    Schäfer, Benjamin; Beck, Christian; Aihara, Kazuyuki; Witthaut, Dirk; Timme, Marc

    2018-02-01

    Multiple types of fluctuations impact the collective dynamics of power grids and thus challenge their robust operation. Fluctuations result from processes as different as dynamically changing demands, energy trading and an increasing share of renewable power feed-in. Here we analyse principles underlying the dynamics and statistics of power grid frequency fluctuations. Considering frequency time series for a range of power grids, including grids in North America, Japan and Europe, we find a strong deviation from Gaussianity best described as Lévy-stable and q-Gaussian distributions. We present a coarse framework to analytically characterize the impact of arbitrary noise distributions, as well as a superstatistical approach that systematically interprets heavy tails and skewed distributions. We identify energy trading as a substantial contribution to today's frequency fluctuations and effective damping of the grid as a controlling factor enabling reduction of fluctuation risks, with enhanced effects for small power grids.

  14. Chemistry in the final stages of stellar evolution: Millimeter and submillimeter observations of supergiants and planetary nebulae

    Science.gov (United States)

    Edwards, Jessica Louise

    High mass loss rates in evolved stars make them the major contributors to recycling processed material back into the interstellar medium. This mass loss creates large circumstellar shells, rich in molecular material. This dissertation presents millimeter and submillimeter studies of the end stages of low mass and high mass stars in order to probe their molecular content in more detail. In low mass stars, the molecular material is carried on into the planetary nebula (PN) stage. Observations of CS, HCO+, and CO in planetary nebulae (PNe) of various post-asymptotic giant branch ages have shown that molecular abundances in these objects do not significantly vary with age, as previously thought. More detailed observations of the slightly oxygen-rich PN NGC 6537 resulted in the detection of CN, HCN, HNC, CCH, CS, SO, H 2CO, HCO+ and N2H+, as well as numerous 13C isotopologues. Observations of the middle-aged PN M2-48 showed the presence of CN, HCN, HNC, CS, SO, SO2, SiO, HCO+, N2H+, and several 13C isotopologues. These observations represent the first detections of CS, SO, SO2, and SiO in any planetary nebula. The implications of these observations are discussed. A 1 mm spectral survey of the supergiant star NML Cygni has been carried out with the Arizona Radio Observatory Submillimeter Telescope resulting in the observation of 102 emission features arising from 17 different molecules and 4 unidentified features. The line profiles observed in this circumstellar shell are asymmetric and vary between different molecules, akin to what has been seen in another supergiant, VY Canis Majoris. The non-LTE radiative transfer code ESCAPADE has been used to model molecular abundances in the various asymmetric outflows of VY Canis Majoris, showing just how chemically and kinematically complex these supergiant circumstellar envelopes really are.

  15. Heterodyne spatial interferometry of circumstellar dust shells at a wavelength of 11 microns

    International Nuclear Information System (INIS)

    Sutton, E.C.

    1979-01-01

    The spatial distribution of the 11 micron thermal emission from circumstellar dust envelopes has been studied using an infrared heterodyne interferometer. Circumstellar dust envelopes often exist around cool, late-type stars. These envelopes radiate strongly at 11 microns, particularly if they are composed of silicate grains, which have a strong emission feature near this wavelength. By measuring the spatial distribution of this dust emission it is possible to probe the temperatures and densities of the circumstellar material and thereby to gain an understanding of the structures of circumstellar envelopes. Among the sources which have been observed with this interferometer are α Orionis, o Ceti, VY Canis Majoris, and IRC + 10216. The 11 micron brightness distributions of these objects all have spatially extended dust-emission components which are resolved in these measurements. The dust envelopes of α Orionis and o Ceti are optically thin, having optical depths at 11 microns of 0.02 and 0.04, respectively. In addition, variations are seen in the 11 micron brightness distribution of o Ceti which correlate with the stellar variability. These variations primarily represent changes in the relative amount of spatially compact photospheric emission and spatially extended dust emission. The source VY Canis Majoris, on the other had, has a dust envelope which is optically thick at 11 microns. The dust envelope of IRC + 10216, although optically thick at visible wavelengths, does not seem to be optically thick at 11 microns since there is a spatially compact component of the 11 micron brightness distribution which presumably represents emission from the central star

  16. Millimeter wave studies of circumstellar chemistry

    Science.gov (United States)

    Tenenbaum, Emily Dale

    2010-06-01

    Millimeter wave studies of molecules in circumstellar envelopes and a planetary nebula have been conducted. Using the Submillimeter Telescope (SMT) of the Arizona Radio Observatory (ARO) on Mt. Graham, a comparative spectral survey from 215-285 GHz was carried out of the carbon-rich asymptotic giant branch star IRC +10216 and the oxygen-rich supergiant VY Canis Majoris. A total of 858 emission lines were observed in both objects, arising from 40 different molecules. In VY Canis Majoris, AlO, AlOH, and PO were detected for the first time in interstellar space. In IRC +10216, PH3 was detected for the first time beyond the solar system, and C3O, and CH2NH were found for the first time in a circumstellar envelope. Additionally, in the evolved planetary nebula, the Helix, H2CO, C2H, and cyclic-C3H2 were observed using the SMT and the Kitt Peak 12 m telescopes. The presence of these three molecules in the Helix suggests that relatively complex chemistry occurs in planetary nebulae, despite the harsh ultraviolet field. Overall, the research on molecules in circumstellar and planetary nebulae furthers our understanding of the nature of the material that is fed back into the interstellar medium from evolved stars. Besides telescope work, laboratory research was also conducted -- the rotational spectrum of ZnCl was measured and its bond length and rotational constants were determined. Lastly, in partial fulfillment of a graduate certificate in entrepreneurial chemistry, the commercial applications of terahertz spectroscopy were explored through literature research.

  17. Likelihood for transcriptions in a genetic regulatory system under asymmetric stable Lévy noise.

    Science.gov (United States)

    Wang, Hui; Cheng, Xiujun; Duan, Jinqiao; Kurths, Jürgen; Li, Xiaofan

    2018-01-01

    This work is devoted to investigating the evolution of concentration in a genetic regulation system, when the synthesis reaction rate is under additive and multiplicative asymmetric stable Lévy fluctuations. By focusing on the impact of skewness (i.e., non-symmetry) in the probability distributions of noise, we find that via examining the mean first exit time (MFET) and the first escape probability (FEP), the asymmetric fluctuations, interacting with nonlinearity in the system, lead to peculiar likelihood for transcription. This includes, in the additive noise case, realizing higher likelihood of transcription for larger positive skewness (i.e., asymmetry) index β, causing a stochastic bifurcation at the non-Gaussianity index value α = 1 (i.e., it is a separating point or line for the likelihood for transcription), and achieving a turning point at the threshold value β≈-0.5 (i.e., beyond which the likelihood for transcription suddenly reversed for α values). The stochastic bifurcation and turning point phenomena do not occur in the symmetric noise case (β = 0). While in the multiplicative noise case, non-Gaussianity index value α = 1 is a separating point or line for both the MFET and the FEP. We also investigate the noise enhanced stability phenomenon. Additionally, we are able to specify the regions in the whole parameter space for the asymmetric noise, in which we attain desired likelihood for transcription. We have conducted a series of numerical experiments in "regulating" the likelihood of gene transcription by tuning asymmetric stable Lévy noise indexes. This work offers insights for possible ways of achieving gene regulation in experimental research.

  18. Individual analyses of Lévy walk in semi-free ranging Tonkean macaques (Macaca tonkeana.

    Directory of Open Access Journals (Sweden)

    Cédric Sueur

    Full Text Available Animals adapt their movement patterns to their environment in order to maximize their efficiency when searching for food. The Lévy walk and the Brownian walk are two types of random movement found in different species. Studies have shown that these random movements can switch from a Brownian to a Lévy walk according to the size distribution of food patches. However no study to date has analysed how characteristics such as sex, age, dominance or body mass affect the movement patterns of an individual. In this study we used the maximum likelihood method to examine the nature of the distribution of step lengths and waiting times and assessed how these distributions are influenced by the age and the sex of group members in a semi free-ranging group of ten Tonkean macaques. Individuals highly differed in their activity budget and in their movement patterns. We found an effect of age and sex of individuals on the power distribution of their step lengths and of their waiting times. The males and old individuals displayed a higher proportion of longer trajectories than females and young ones. As regards waiting times, females and old individuals displayed higher rates of long stationary periods than males and young individuals. These movement patterns resembling random walks can probably be explained by the animals moving from one location to other known locations. The power distribution of step lengths might be due to a power distribution of food patches in the enclosure while the power distribution of waiting times might be due to the power distribution of the patch sizes.

  19. First molecular evidence of Hepatozoon canis infection in red foxes and golden jackals from Hungary.

    Science.gov (United States)

    Farkas, Róbert; Solymosi, Norbert; Takács, Nóra; Hornyák, Ákos; Hornok, Sándor; Nachum-Biala, Yaarit; Baneth, Gad

    2014-07-02

    Recently, Hepatozoon canis infection has been detected among shepherd, hunting and stray dogs in the southern part of Hungary, which is considered to be free of Rhipicephalus sanguineus sensu lato and close to the border with Croatia. The aim of this study was to acquire information on the possibility that red foxes and/or golden jackals could play a role in the appearance and spread of H. canis in Hungary. A conventional PCR was used to amplify a 666 bp long fragment of the Hepatozoon 18S rRNA gene from blood samples collected from 334 foxes shot in 231 locations in 16 counties and 15 golden jackals shot in 9 locations in two southwestern counties close to Croatia. A second PCR assay was performed in some of the samples positive by the first PCR to amplify a larger segment (approximately 1500 bp) of the 18S rRNA gene of Hepatozoon spp. for further phylogenetic analysis. Hepatozoon infection was detected in canids shot in 30 locations and 9 counties. Altogether 26 foxes (8.0%, 95% CI: 5-11%) and 9 jackals (60%, 95% CI: 33-81%) were PCR positive. Hepatozoon canis sequences were obtained from 12 foxes and 7 jackals. DNA sequences from 16 animals were 99-100% similar to H. canis from Croatian foxes or dogs while two of the sequences were 99% similar to an Italian fox. Half (13/26) of the infected red foxes and all golden jackals were shot in the two southwestern counties. This is the first report on molecular evidence of H. canis in red foxes (Vulpes vulpes) and golden jackals (Canis aureus) from Hungary, which is considered free from the tick vector of H. canis, R. sanguineus. Although no R. sanguineus sensu lato had been found on infected or non-infected wild canids, the detection of authochnous canine hepatozoonosis in Hungary might imply that the range of R. sanguineus sensu lato has reached this country.

  20. Digital gene expression analysis of Microsporum canis exposed to berberine chloride.

    Directory of Open Access Journals (Sweden)

    Chen-Wen Xiao

    Full Text Available Berberine, a natural isoquinoline alkaloid of many medicinal herbs, has an active function against a variety of microbial infections including Microsporum canis (M. canis. However, the underlying mechanisms are poorly understood. To study the effect of berberine chloride on M. canis infection, a Digital Gene Expression (DGE tag profiling was constructed and a transcriptome analysis of the M. canis cellular responses upon berberine treatment was performed. Illumina/Hisseq sequencing technique was used to generate the data of gene expression profile, and the following enrichment analysis of Gene Ontology (GO and Pathway function were conducted based on the data of transcriptome. The results of DGE showed that there were 8476945, 14256722, 7708575, 5669955, 6565513 and 9303468 tags respectively, which was obtained from M. canis incubated with berberine or control DMSO. 8,783 genes were totally mapped, and 1,890 genes have shown significant changes between the two groups. 1,030 genes were up-regulated and 860 genes were down-regulated (P<0.05 in berberine treated group compared to the control group. Besides, twenty-three GO terms were identified by Gene Ontology functional enrichment analysis, such as calcium-transporting ATPase activity, 2-oxoglutarate metabolic process, valine catabolic process, peroxisome and unfolded protein binding. Pathway significant enrichment analysis indicated 6 signaling pathways that are significant, including steroid biosynthesis, steroid hormone biosynthesis, Parkinson's disease, 2,4-Dichlorobenzoate degradation, and tropane, piperidine and Isoquinoline alkaloid biosynthesis. Among these, eleven selected genes were further verified by qRT-PCR. Our findings provide a comprehensive view on the gene expression profile of M. canis upon berberine treatment, and shed light on its complicated effects on M. canis.

  1. A golden jackal (Canis aureus) from Austria bearing Hepatozoon canis--import due to immigration into a non-endemic area?

    Science.gov (United States)

    Duscher, Georg Gerhard; Kübber-Heiss, Anna; Richter, Barbara; Suchentrunk, Franz

    2013-02-01

    The protozoan Hepatozoon canis, which is transmitted via ingestion of infected ticks by canine hosts, is not endemic to mid-latitude regions in Europe. Its distribution is supposed to be linked to the occurrence of its primary tick vector Rhipicephalus sanguineus. A young male golden jackal (Canis aureus) found as road kill close to Vienna, Austria, was infected by this pathogen. Cloning and sequencing of the PCR product revealed 6 different haplotypes of H. canis. Based on the sequences, no clear relationship to the origin of infection could be traced. This is the first report of H. canis for Austria, and wild canines such as the currently found jackal may provide a source of natural spread of this parasite into non-endemic areas. This natural immigration of wild animals represents a way of pathogen introduction, which has to be considered in disease prevention in addition to human-made introduction due to animal import and export. Copyright © 2012 Elsevier GmbH. All rights reserved.

  2. Critical analysis of vector-borne infections in dogs: Babesia vogeli, Babesia gibsoni, Ehrlichia canis and Hepatozoon canis in Punjab, India.

    Science.gov (United States)

    Singla, Lachhman Das; Sumbria, Deepak; Mandhotra, Ajay; Bal, M S; Kaur, Paramjit

    2016-12-01

    There are few published studies on various vector borne diseases of dogs in India and most depict clinical infection in dogs, diagnosed by observation of the haemopathogens in stained blood smears. This study provides the first report regarding molecular confirmation and ancestral relationship analysis of blood smears positive cases of assorted haemopathogens in Punjab province of India. On blood smear examination, haemopathogens were observed in 124 out of 778 (15.95%, 95% CI: 13.53- 18.68) blood smears. Further polymerase chain reactions (PCR) was used on bloods smear positive cases to validate the results. Out of 778 blood samples, Babesia gibsoni was most common parasite infecting dogs (15.04%, 95% CI: 12.7-17.72), followed by Ehrlichia canis (0.39%, 95% CI: 0.0-1.13), infection of Babesia vogeli and Hepatozoon canis was same (0.26%, 95% CI: 0.0-0.9). Among various risk factors studied (age, sex, season), prevalence of infection was non-significantly higher in 1-2 year of age group (19.88%, 95% CI: 14.45-26.71), regarding sex same prevalence was recorded (15.94%), and chances of infection was highest in pre-monsoon i.e. summer (18.26%, 95% CI: 14.49-22.76). Phylogenetic analysis revealed ancestral background of Ludhiana isolates of B. vogeli, B. gibsoni, H. canis, and E. canis with the isolates of Philippines, Mongolia and Tunisia.

  3. Detecção molecular de Ehrlichia canis e Babesia canis vogeli em Rhipicephalus sanguineus sensu lato de carrapatos em Cuba

    Directory of Open Access Journals (Sweden)

    Maylin Gonzalez Navarrete

    2016-12-01

    Full Text Available Os carrapatos (Acari: Ixodidae são de importância médica e veterinária relevantes em todo o mundo por causa da variedade de agentes patogênicos que podem transmitir. No presente trabalho, foi realizada uma pesquisa para identificar Babesia spp. e Ehrlichia spp. em carrapatos coletados de cães de Cuba. Foram coletados 431 carrapatos de 378 cães, tendo sido identificados como pertencentes às espécies de Ripicephalus sanguineus sensu lato (s. 1. O DNA genômico foi extraído com protocolo usando fenol/clorofórmio. Os carrapatos foram organizados em “pools” e o DNA extraído foi testado pela reação em cadeia da polimerase (nPCR para amplificar 398 pares de bases (pb do DNA ribossômico 16S (rDNA de Ehrlichia canis e PCR para amplificar aproximadamente 560 pb do DNA ribossômico 18S (rDNA. Dos 49 pools testados, 8,16% (n = 4/49 foram positivos para o E. canis por nPCR visando o gene do 16S rDNA e apenas um pool (n = 1/49; 2,04% foi positivo para o gene 18S rDNA para Babesia canis. As quatro sequências obtidas para o fragmento de 16S rDNA foram idênticas entre si e resultaram em 100% de identidade com E. canis de diferentes países. A sequência obtida do gene do 18S rDNA para Babesia spp. apresentou semelhança de 100% com Babesia canis vogeli quando comparada às sequências depositadas no Genbank. Esta foi a primeira detecção molecular desses agentes no carrapato R. sanguineus s. l. em Cuba.

  4. A condition-based maintenance policy for multi-component systems with Lévy copulas dependence

    International Nuclear Information System (INIS)

    Li, Heping; Deloux, Estelle; Dieulle, Laurence

    2016-01-01

    In this paper, we propose a new condition-based maintenance policy for multi-component systems taking into account stochastic and economic dependences. The stochastic dependence between components due to common environment is modelled by Lévy copulas. Its influence on the maintenance optimization is investigated with different dependence degrees. On the issue of economic dependence providing opportunities to group maintenance activities, a new maintenance decision rule is proposed which permits maintenance grouping. In order to evaluate the performance of the proposed maintenance policy, we compare it to the classical maintenance policies. - Highlights: • A new adaptive maintenance policy for grouping maintenance actions is proposed. • The impacts of both economic and stochastic dependences are investigated. • The performance of the proposed maintenance policy is evaluated under different system configurations. • The stochastic dependence is modelled by Lévy copulas. • The proposed maintenance decision rule can take full advantage of economic and stochastic dependences.

  5. Optimality of the barrier strategy in de Finetti's dividend problem for spectrally negative Lévy processes: An alternative approach

    Science.gov (United States)

    Yin, Chuancun; Wang, Chunwei

    2009-11-01

    The optimal dividend problem proposed in de Finetti [1] is to find the dividend-payment strategy that maximizes the expected discounted value of dividends which are paid to the shareholders until the company is ruined. Avram et al. [9] studied the case when the risk process is modelled by a general spectrally negative Lévy process and Loeffen [10] gave sufficient conditions under which the optimal strategy is of the barrier type. Recently Kyprianou et al. [11] strengthened the result of Loeffen [10] which established a larger class of Lévy processes for which the barrier strategy is optimal among all admissible ones. In this paper we use an analytical argument to re-investigate the optimality of barrier dividend strategies considered in the three recent papers.

  6. Optimal portfolio selection in a Lévy market with uncontrolled cash flow and only risky assets

    Science.gov (United States)

    Zeng, Yan; Li, Zhongfei; Wu, Huiling

    2013-03-01

    This article considers an investor who has an exogenous cash flow evolving according to a Lévy process and invests in a financial market consisting of only risky assets, whose prices are governed by exponential Lévy processes. Two continuous-time portfolio selection problems are studied for the investor. One is a benchmark problem, and the other is a mean-variance problem. The first problem is solved by adopting the stochastic dynamic programming approach, and the obtained results are extended to the second problem by employing the duality theory. Closed-form solutions of these two problems are derived. Some existing results are found to be special cases of our results.

  7. [Dog (Canis familiaris) infectivity to Lutzomyia youngi in Trujillo, Venezuela].

    Science.gov (United States)

    Hernández, Dalila; Rojas, Elina; Scorza, José Vicente; Jorquera, Alicia

    2006-10-01

    In Trujillo, Venezuela the prevalence for American tegumentary leishmaniasis (ATL) is 38 per 100,000 inhabitants. In a periurban, rural settlement of the capital city Trujillo, we studied the potential capability of the domestic dog (Canis familiaris) as a source of infection for Lutzomyia youngi, a phlebotomine sand fly species abundant in the study area and whose domestic vectorial activity has been proven. Dogs with dermal lesions suggestive of ATL and parasitological confirmation of infection, were selected for xenodiagnosis by allowing sylvatic phlebotomines from a ATL free area, to feed ad libitum over each animal's entire body surface. The insects' intestinal tracts were dissected 5 days after the blood meal in order to look for flagellate forms. When these were found, parasitological identification was performed by the multiplex-PCR technique. Four hundred and fifty five sand flies engorged over two dogs in three different assays; promastigotes were found in 4 (0.88%) of the specimens on only one occasion. PCR identified DNA of the Leishmania Viannia subgenus. The household dog has the potential of being a domestic risk factor in the ATL transmission cycle.

  8. Accounts of famous North American Wolves, Canis lupus

    Science.gov (United States)

    Gipson, P.S.; Ballard, W.B.

    1998-01-01

    We examined historical accounts of 59 famous North American Gray Wolves (Canis lupus) reported during the late nineteenth and early twentieth centuries. Fifty of the 59 wolves were purportedly responsible for great losses to livestock, but for 29 reports, evidence suggested that ???2 wolves (e.g., packs) were responsible for the purported kills; in addition, seven wolves had traits that suggested they were hybrids with dogs, and one wolf was probably not from the area where the damage purportedly occurred. Reported livestock losses, especially to Longhorn cattle, from individual wolves appeared excessively high in relation to current literature. Most famous wolves were old and/or impaired from past injuries: 19 were reportedly ???10 years old, 18 had mutilated feet from past trap injuries, and one had a partially severed trachea from being in a snare. Old age and physical impairments probably contributed to livestock depredations by some famous wolves. Several accounts appeared exaggerated, inaccurate, or fabricated. Historical accounts of famous wolves should be interpreted with great caution, especially when considering impacts of wolf reintroductions or when modeling predation rates.

  9. Helminth parasites in the endangered Ethiopian wolf, Canis simensis.

    Science.gov (United States)

    van Kesteren, F; Piggott, K J; Bengui, T; Kubri, S B; Mastin, A; Sillero-Zubiri, C; Paris, M; Millar, R P; Macdonald, D W; Shiferaw, F; Craig, P S

    2015-07-01

    Ethiopian wolves, Canis simensis, are an endangered carnivore endemic to the Ethiopian highlands. Although previous studies have focused on aspects of Ethiopian wolf biology, including diet, territoriality, reproduction and infectious diseases such as rabies, little is known of their helminth parasites. In the current study, faecal samples were collected from 94 wild Ethiopian wolves in the Bale Mountains of southern Ethiopia, between August 2008 and February 2010, and were screened for the presence of helminth eggs using a semi-quantitative volumetric dilution method with microscopy. We found that 66 of the 94 faecal samples (70.2%) contained eggs from at least one group of helminths, including Capillaria, Toxocara, Trichuris, ancylostomatids, Hymenolepis and taeniids. Eggs of Capillaria sp. were found most commonly, followed by Trichuris sp., ancylostomatid species and Toxocara species. Three samples contained Hymenolepis sp. eggs, which were likely artefacts from ingested prey species. Four samples contained taeniid eggs, one of which was copro-polymerase chain reaction (copro-PCR) and sequence positive for Echinococcus granulosus, suggesting a spillover from a domestic parasite cycle into this wildlife species. Associations between presence/absence of Capillaria, Toxocara and Trichuris eggs were found; and egg burdens of Toxocara and ancylostomatids were found to be associated with geographical location and sampling season.

  10. Where and How Wolves (Canis lupus Kill Beavers (Castor canadensis.

    Directory of Open Access Journals (Sweden)

    Thomas D Gable

    Full Text Available Beavers (Castor canadensis can be a significant prey item for wolves (Canis lupus in boreal ecosystems due to their abundance and vulnerability on land. How wolves hunt beavers in these systems is largely unknown, however, because observing predation is challenging. We inferred how wolves hunt beavers by identifying kill sites using clusters of locations from GPS-collared wolves in Voyageurs National Park, Minnesota. We identified 22 sites where wolves from 4 different packs killed beavers. We classified these kill sites into 8 categories based on the beaver-habitat type near which each kill occurred. Seasonal variation existed in types of kill sites as 7 of 12 (58% kills in the spring occurred at sites below dams and on shorelines, and 8 of 10 (80% kills in the fall occurred near feeding trails and canals. From these kill sites we deduced that the typical hunting strategy has 3 components: 1 waiting near areas of high beaver use (e.g., feeding trails until a beaver comes near shore or ashore, 2 using vegetation, the dam, or other habitat features for concealment, and 3 immediately attacking the beaver, or ambushing the beaver by cutting off access to water. By identifying kill sites and inferring hunting behavior we have provided the most complete description available of how and where wolves hunt and kill beavers.

  11. INTEREST OF FINITE ELEMENT ANALYSIS TO DETERMINE STRESS FIELDS AT THE SUMMIT OF A VY FLAP ABOUT ONE CLINICAL CASE

    OpenAIRE

    Pauchot , Julien; Remache , Djamel; Chambert , Jérôme; Elkhyat , Ahmed; Jacquet , Emmanuelle

    2013-01-01

    International audience; After performing a V-Y advancement flap, we observed an unusually shaped necrosis, resembling a keyhole at the apex of the flap. As high closing tensions are an accepted cause of skin necrosis, we developed a mathematical model based on the finite element analysis in order to determine the stress field by simulating the mechanical behavior of human skin during suture and to explain this particular shape of necrosis. For the modeling, a planar nonlinear two-dimensional ...

  12. Detection and molecular identification of Hepatozoon canis and Babesia vogeli from domestic dogs in Palestine.

    Science.gov (United States)

    Azmi, Kifaya; Al-Jawabreh, Amer; Nasereddin, Abedelmajeed; Abdelkader, Ahmad; Zaid, Taher; Ereqat, Suheir; Sawalha, Samer S; Baneth, Gad; Abdeen, Ziad

    2017-04-01

    Dogs serve as hosts for a great number of parasites, which may affect their health and wellbeing. This study aimed to observe tick borne pathogens in dogs from Palestine including Hepatozoon canis and Babesia species. The prevalence of both H. canis and Babesia species infections in apparently healthy dogs, from ten districts of the West Bank was surveyed. DNA was extracted from blood samples obtained from dogs (n = 362) and ticks (n = 213) collected from dogs (n = 77). A primer set that amplifies a partial sequence of the Babesia and Hepatozoon 18S rRNA gene was used for PCR and the DNA sequences of the PCR products of all samples were determined. Twenty-nine (8·0%) of the dogs were found infected including 20 with H. canis (5·5%), seven with Babesia vogeli (1·9%) and two with undefined Babesia spp. (0·6%). Twelve Rhipicephalus sanguineus s.l ticks were pathogen-positive, including ten with H. canis (4·7%), one with B. vogeli (0·5%), and one with Hepatozoon felis (0·5%). The results indicated that a wide range of tick borne pathogens is circulating in the canine population in the surveyed region. This study is the first report on the prevalence of H. canis, B. vogeli and Babesia spp. in dogs in Palestine and its results will assist in the management of diseases associated with these blood parasites.

  13. Trichoderma virens as a biocontrol of Toxocara canis: In vivo evaluation.

    Science.gov (United States)

    de Souza Maia Filho, Fernando; da Silva Fonseca, Anelise Oliveira; Persici, Beatriz Maroneze; de Souza Silveira, Julia; Braga, Caroline Quintana; Pötter, Luciana; de Avila Botton, Sônia; Brayer Pereira, Daniela Isabel

    Microorganisms have been widely studied as biological control agents of parasites of medical and veterinary importance. Coprophagous arthropods, bacteria and fungi are among the different organisms evaluated as potential biological control agents. Nematophagous fungi capture and digest the free forms of nematodes in the soil. Due to its zoonotic potential, Toxocara canis have been brought to the attention of researchers. The aim of the present study was to determine whether the administration of embryonated T. canis eggs exposed to the nematophagous fungus Trichoderma virens reduces parasite infection in experimental animals. Embryonated T. canis eggs were exposed to T. virens mycelium for 15 days at 25°C. Subsequently, 100 fungus-exposed eggs were orally administered to 20 Swiss mice. As a positive control, another 20 mice received 100 embryonated eggs that were not exposed to the fungus. After 48h, the animals were killed, and heart, lungs and liver were harvested for the recovery of larvae. The organs of the animals that received embryonated T. canis eggs exposed to the fungus showed a lower mean larval recovery when compared with the animals that received embryonated eggs without fungus exposure (p<0.05). The exposure of T. canis eggs to T. virens reduces the experimental infection, demonstrating the potential of this nematophagous fungus as a biocontrol agent. Copyright © 2016 Asociación Española de Micología. Publicado por Elsevier España, S.L.U. All rights reserved.

  14. Babesia canis vogeli infection in dogs and ticks in the semiarid region of Pernambuco, Brazil

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    Andreina C. Araujo

    2015-05-01

    Full Text Available Abstract:This study aimed to report the prevalence of Babesia canis vogeli in dogs and ticks in the urban and rural areas of Petrolina, Pernambuco. Serum and peripheral blood samples of 404 dogs were tested by indirect immunofluorescence assay (IFA and by blood smears, respectively. The presence of tick infestation was evaluated, and some specimens were submitted to DNA amplification by polymerase chain reaction (PCR. The presence of antibodies anti-B. canis vogeli was determinate in 57.9% (234/404 of dogs. The direct detection of Babesia spp was obtained in 0.5% (2/404 dogs by visualization of intraerythrocytic forms. Infestation by Rhipicephalus sanguineus sensu lato was observed in 54.5% (220/404 of dogs in both urban and rural areas. DNA of Babesia canis vogeli were obtained by PCR in 6% individual (3/50 and 8.7% of pool of ticks (7/80. The risk factors for the presence of anti-B. canis vogeli antibodies, as determined through the application of logistic regression models (P<0.05, were the following: medium breed size variables (P<0.001; contact with areas of forest (P=0.021; and access on the street (P=0.046. This study describes, for the first time, the confirmation of infection of B. canis vogeli in dogs and ticks in the semiarid region of Pernambuco, Brazil.

  15. Evidence of morphine like substance and μ-opioid receptor expression in Toxacara canis (Nematoda: Ascaridae).

    Science.gov (United States)

    Golabi, Mostafa; Naem, Soraya; Imani, Mehdi; Dalirezh, Nowruz

    2016-01-01

    Toxocara canis (Nematoda: Ascaridae) is an intestinal nematode parasite of dogs, which can also cause disease in humans. Transmission to humans usually occurs because of direct contact with T. canis eggs present in soil contaminated with the feces of infected dogs. This nematode has extraordinary abilities to survive for many years in different tissues of vertebrates, and develop to maturity in the intestinal tract of its definitive host. Survival of parasitic nematodes within a host requires immune evasion using complicated pathways. Morphine-like substance, as well as opioids, which are known as down regulating agents, can modulate both innate and acquired immune responses, and let the parasite survives in their hosts. In the present study, we aimed to find evidences of morphine-like substance and µ-opiate receptor expression in T. canis , using high performance liquid chromatography (HPLC) and reverse transcription polymerase chain reaction (RT-PCR). The results indicated that T. canis produced morphine-like substances at the level of 2.31± 0.26 ng g -1 wet weight, and expressed µ-opiate receptor as in expected size of 441 bp. According to our findings, it was concluded that T. canis , benefits using morphine-like substance to modulate host immunity.

  16. Molecular cloning and characterization of arginine kinase gene of Toxocara canis.

    Science.gov (United States)

    Sahu, Shivani; Samanta, S; Harish, D R; Sudhakar, N R; Raina, O K; Shantaveer, S B; Madhu, D N; Kumar, Ashok

    2015-06-01

    Toxocara canis is an important gastrointestinal nematode of dogs and also a causative agent of visceral larva migrans in humans. Arginine kinase (AK) gene is one of the important biomolecule of phosphagen kinase of T. canis which is emerging as an exciting novel diagnostic target in toxocarosis. The present study was carried out to clone and characterize AK gene of T. canis for future utilization as a diagnostic molecule. Total RNA was extracted from intact adult worms and reverse transcription was done with oligo dT primers to obtain complementary DNA (cDNA). Polymerase chain reaction (PCR) was carried out using cDNA as template with specific primers which amplified a product of 1,202 bp. The amplicon was cloned into pDrive cloning vector and clone was confirmed by colony PCR and restriction endonuclease analysis. Sequence analysis of the gene showed 99.8 and 77.9 % homology with the published AK gene of T. canis (EF015466.1) and Ascaris suum respectively. Structural analysis shown that the mature AK protein consist of 400 amino acids with a molecular wt of 45360.73 Da. Further expression studies are required for producing the recombinant protein for its evaluation in the diagnosis of T. canis infection in humans as well as in adult dogs.

  17. The “Lévy or Diffusion” Controversy: How Important Is the Movement Pattern in the Context of Trapping?

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    Danish A. Ahmed

    2018-05-01

    Full Text Available Many empirical and theoretical studies indicate that Brownian motion and diffusion models as its mean field counterpart provide appropriate modeling techniques for individual insect movement. However, this traditional approach has been challenged, and conflicting evidence suggests that an alternative movement pattern such as Lévy walks can provide a better description. Lévy walks differ from Brownian motion since they allow for a higher frequency of large steps, resulting in a faster movement. Identification of the ‘correct’ movement model that would consistently provide the best fit for movement data is challenging and has become a highly controversial issue. In this paper, we show that this controversy may be superficial rather than real if the issue is considered in the context of trapping or, more generally, survival probabilities. In particular, we show that almost identical trap counts are reproduced for inherently different movement models (such as the Brownian motion and the Lévy walk under certain conditions of equivalence. This apparently suggests that the whole ‘Levy or diffusion’ debate is rather senseless unless it is placed into a specific ecological context, e.g., pest monitoring programs.

  18. Freestyle-Like V-Y Flaps of the Eyebrow: A New Outlook and Indication of an Historical Technique

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    Angelo Alberto Leto Barone

    2013-01-01

    Full Text Available The eyebrow region is of utmost importance for facial movement, symmetry, and the overall cosmetic appearance of the face. Trauma or tumor resection often leave scars that may dislocate the eyebrow producing an alteration both in static symmetry of the face and in the dynamic expressivity. The authors present a technique for eyebrow’s defects repair using the remaining eyebrow advancement by means of a “freestyle-like” V-Y flap. In the past two years a total of eight consecutive patients underwent excision of skin lesions in the superciliary region and immediate reconstruction with this technique. On histology, six patients were affected from basal cell carcinomas, one from squamous cell carcinoma, and one from congenital intradermal melanocytic nevus. The pedicle of the flap included perforators from the supratrochlear, supraorbital, or superficial temporalis artery. Advancement of the entire aesthetic subunit that includes the eyebrow using a V-Y perforator flap was performed successfully in all cases achieving full, tension-free closure of defects up to 3.0 cm. “Freestyle-like” V-Y flaps should be considered as a first-line choice for partial defects of the eyebrow. The greater mobility compared to random subcutaneous flaps allows to reconstruct large defects providing an excellent cosmetic result.

  19. Boltzmann-distribution-equivalent for Lévy noise and how it leads to thermodynamically consistent epicatalysis

    Science.gov (United States)

    Bier, Martin

    2018-02-01

    Nonequilibrium systems commonly exhibit Lévy noise. This means that the distribution for the size of the Brownian fluctuations has a "fat" power-law tail. Large Brownian kicks are then more common as compared to the ordinary Gaussian distribution. We consider a two-state system, i.e., two wells and a barrier in between. The barrier is sufficiently high for a barrier crossing to be a rare event. When the noise is Lévy, we do not get a Boltzmann distribution between the two wells. Instead we get a situation where the distribution between the two wells also depends on the height of the barrier that is in between. Ordinarily, a catalyst, by lowering the barrier between two states, speeds up the relaxation to an equilibrium, but does not change the equilibrium distribution. In an environment with Lévy noise, on the other hand, we have the possibility of epicatalysis, i.e., a catalyst effectively altering the distribution between two states through the changing of the barrier height. After deriving formulas to quantitatively describe this effect, we discuss how this idea may apply in nuclear reactors and in the biochemistry of a living cell.

  20. Optimal harvesting of a stochastic delay tri-trophic food-chain model with Lévy jumps

    Science.gov (United States)

    Qiu, Hong; Deng, Wenmin

    2018-02-01

    In this paper, the optimal harvesting of a stochastic delay tri-trophic food-chain model with Lévy jumps is considered. We introduce two kinds of environmental perturbations in this model. One is called white noise which is continuous and is described by a stochastic integral with respect to the standard Brownian motion. And the other one is jumping noise which is modeled by a Lévy process. Under some mild assumptions, the critical values between extinction and persistent in the mean of each species are established. The sufficient and necessary criteria for the existence of optimal harvesting policy are established and the optimal harvesting effort and the maximum of sustainable yield are also obtained. We utilize the ergodic method to discuss the optimal harvesting problem. The results show that white noises and Lévy noises significantly affect the optimal harvesting policy while time delays is harmless for the optimal harvesting strategy in some cases. At last, some numerical examples are introduced to show the validity of our results.

  1. From standard alpha-stable Lévy motions to horizontal visibility networks: dependence of multifractal and Laplacian spectrum

    Science.gov (United States)

    Zou, Hai-Long; Yu, Zu-Guo; Anh, Vo; Ma, Yuan-Lin

    2018-05-01

    In recent years, researchers have proposed several methods to transform time series (such as those of fractional Brownian motion) into complex networks. In this paper, we construct horizontal visibility networks (HVNs) based on the -stable Lévy motion. We aim to study the relations of multifractal and Laplacian spectrum of transformed networks on the parameters and of the -stable Lévy motion. First, we employ the sandbox algorithm to compute the mass exponents and multifractal spectrum to investigate the multifractality of these HVNs. Then we perform least squares fits to find possible relations of the average fractal dimension , the average information dimension and the average correlation dimension against using several methods of model selection. We also investigate possible dependence relations of eigenvalues and energy on , calculated from the Laplacian and normalized Laplacian operators of the constructed HVNs. All of these constructions and estimates will help us to evaluate the validity and usefulness of the mappings between time series and networks, especially between time series of -stable Lévy motions and HVNs.

  2. Cross-infection between cats and cows: origin and control of Streptococcus canis mastitis in a dairy herd.

    Science.gov (United States)

    Tikofsky, L L; Zadoks, R N

    2005-08-01

    Group G streptococci in animals usually belong to the species Streptococcus canis and are most commonly found in dogs and cats. Occasionally, Strep. canis is detected in milk from dairy cows. An outbreak of Strep. canis mastitis in a dairy herd is described. Based on results from bacterial culture and ribotyping, a cat with chronic sinusitis was the most likely source of the outbreak. Subsequent cow-to-cow transmission of Strep. canis was facilitated by poor udder health management, including use of a common udder cloth and failure to use postmilking teat disinfection. Infected cows had macroscopically normal udders and milk, but significantly higher somatic cell counts than Strep. canis-negative herd mates. The outbreak was controlled through antibiotic treatment of lactating cows, early dry-off with dry cow therapy, culling of infected animals, and implementation of standard mastitis prevention measures. Cure was significantly more likely in dry-treated cows (87.5%) and cows treated during lactation (67%) than in untreated cows (9%). Whereas mastitis due to group G streptococci or Strep. canis in dairy cows is usually limited to sporadic cases of environmental (canine or feline) origin, this case study shows that crossing of the host species barrier by Strep. canis may result in an outbreak of mastitis if management conditions are conducive to contagious transmission. In such a situation, measures that are successful in control of Strep. agalactiae can also be used to control Strep. canis mastitis.

  3. CONSTRAINTS ON THE SURFACE MAGNETIC FIELDS AND AGE OF A COOL HYPERGIANT: XMM-NEWTON X-RAY OBSERVATIONS OF VY CMa

    International Nuclear Information System (INIS)

    Montez, Rodolfo Jr.; Kastner, Joel H.; Humphreys, Roberta M.; Davidson, Kris; Turok, Rebecca L.

    2015-01-01

    The complex circumstellar ejecta of highly evolved, cool hypergiants are indicative of multiple, asymmetric mass-loss events. To explore whether such episodic, non-isotropic mass loss may be driven by surface magnetic activity, we have observed the archetypical cool hypergiant VY CMa with the XMM-Newton X-ray satellite observatory. The hypergiant itself is not detected in these observations. From the upper limit on the X-ray flux from VY CMa at the time of our observations (F X, UL ≈ 8 × 10 –14 erg cm –2 s –1 , corresponding to log L X /L bol ≤ –8), we estimate an average surface magnetic field strength fB ≤ 2 × 10 –3 G (where f is the filling factor of magnetically active surface regions). These X-ray results for VY CMa represent the most stringent constraints to date on the magnetic field strength near the surface of a hypergiant. VY CMa's mass loss is episodic, however, and the hypergiant may have been in a state of low surface magnetic activity during the XMM observations. The XMM observations also yield detections of more than 100 X-ray sources within ∼15' of VY CMa, roughly 50 of which have near-infrared counterparts. Analysis of X-ray hardness ratios and IR colors indicates that some of these field sources may be young, late-type stars associated with VY CMa, its adjacent molecular cloud complex, and the young cluster NGC 2362. Further study of the VY CMa field is warranted, given the potential to ascertain the evolutionary timescale of this enigmatic, massive star

  4. The dog mite, Demodex canis: prevalence, fungal co-infection, reactions to light, and hair follicle apoptosis.

    Science.gov (United States)

    Tsai, Yu-Jen; Chung, Wen-Cheng; Wang, Lian-Chen; Ju, Yu-Ten; Hong, Chin-Lin; Tsai, Yu-Yang; Li, Yi-Hung; Wu, Ying-Ling

    2011-01-01

    Infection rate, reaction to light, and hair follicle apoptosis are examined in the dogmite, Demodex canis Leydig (Prostigmata: Demodicidae), in dogs from the northern area of Taiwan. An analysis of relevant samples revealed 7.2% (73/1013) prevalence of D. canis infection. Infection during the investigation peaked each winter, with an average prevalence of 12.5% (32/255). The infection rates significantly varied in accordance with month, sex, age, and breed (p canis Bodin (Onygenales: Arthrodermataceae) and Trichophyton mentagrophyte Robin (Blanchard) on the D. canis infected dogs revealed prevalence rates of 4.4% (2/45) and 2.2% (1/45), respectively. Observations demonstrated that D. canis slowly moved from a light area to a dark area. Skin samples were examined for cellular apoptosis by activated caspase3 immunohistochemical staining. Cells that surrounded the infected hair follicles were activated caspase3-positive, revealing cell apoptosis in infected follicles via the activation of caspase3.

  5. The infection of questing Dermacentor reticulatus ticks with Babesia canis and Anaplasma phagocytophilum in the Chernobyl exclusion zone.

    Science.gov (United States)

    Karbowiak, Grzegorz; Vichová, Bronislavá; Slivinska, Kateryna; Werszko, Joanna; Didyk, Julia; Peťko, Branislav; Stanko, Michal; Akimov, Igor

    2014-08-29

    Tick occurrence was studied in the Chernobyl exclusion zone (CEZ) during the August-October 2009-2012. Dermacentor reticulatus ticks were collected using the flagging method and then screened for infection with Anaplasma phagocytophilum and Babesia canis by a PCR method incorporating specific primers and sequence analysis. The prevalence of infection with B. canis canis and A. phagocytophilum was found to be 3.41% and 25.36%, respectively. The results present the first evidence of B. canis canis and A. phagocytophilum in questing D. reticulatus ticks from the Chernobyl exclusion zone. They also reveal the presence of tick-borne disease foci in areas with no human activity, and confirm that they can be maintained in areas after a nuclear disaster with radioactive contamination. Copyright © 2014 Elsevier B.V. All rights reserved.

  6. Detection of Hepatozoon canis in the Brown Dog Tick and Domestic Dogs in Peninsular Malaysia.

    Science.gov (United States)

    Prakash, Batah Kunalan; Low, Van Lun; Tan, Tiong Kai; Vinnie-Siow, Wei Yin; Lim, Yvonne Ai-Lian; Morvarid, Akhavan Rezaei; Azman, Adzzie Shazleen; Yeong, Yze Shiuan; AbuBakar, Sazaly; Sofian-Azirun, Mohd

    2018-05-17

    Hepatozoon canis has been widely reported in dogs. Its prevalence in ticks, however, has not been well-established. Here we determine the occurrence of Hepatozoon DNA in the brown dog tick Rhipicephalus sanguineus (Latreille) (Acari: Ixodidae) sensu lato (s.l.) and domestic dogs from Peninsular Malaysia using a polymerase chain reaction (PCR) assay based on amplification of the 18S ribosomal RNA coding sequence. Our results revealed a relatively low prevalence of H. canis DNA in both R. sanguineus s.l. (0.7%) and dogs (3.33%). This study represents the first report of H. canis DNA in R. sanguineus s.l. in Malaysia, highlighting the risk of this infection in dogs.

  7. Rangelia vitalii and Hepatozoon canis coinfection in pampas fox Lycalopex gymnocercus from Santa Catarina State, Brazil

    Directory of Open Access Journals (Sweden)

    Maria Regina Lucas da Silva

    2018-05-01

    Full Text Available Abstract Rangelia vitalii is a haemoparasite that infects erythrocytes, white blood cells and the cytoplasm of endothelial cells of blood capillaries of canids in South America, and has been detected in both domestic dogs and sylvatic canids. Hepatozoon canis is a parasite that infects neutrophils and monocytes of many mammalian hosts. This study reports the infection of Lycalopex gymnocercus from Santa Catarina, Brazil, with R. vitalii and H. canis. The piroplasm was observed on both blood smears and molecular tests. Many large piroplasms were detected inside the erythrocytes, with round, oval, or teardrop-shaped organism, that occurred singly or in pairs. They had an abundant, pale blue cytoplasm and decentral dark red small nucleus. The animal was also infected with H. canis that was detected only by molecular tests. The majority of haematological and biochemistry parameters were within the reference values for domestic dog and wild canids.

  8. Rangelia vitalii and Hepatozoon canis coinfection in pampas fox Lycalopex gymnocercus from Santa Catarina State, Brazil.

    Science.gov (United States)

    Silva, Maria Regina Lucas da; Mattoso, Cláudio Roberto Scabelo; Costa, Adson; Saito, Mere Erika; Tchaicka, Lygia; O'Dwyer, Lucia Helena

    2018-05-24

    Rangelia vitalii is a haemoparasite that infects erythrocytes, white blood cells and the cytoplasm of endothelial cells of blood capillaries of canids in South America, and has been detected in both domestic dogs and sylvatic canids. Hepatozoon canis is a parasite that infects neutrophils and monocytes of many mammalian hosts. This study reports the infection of Lycalopex gymnocercus from Santa Catarina, Brazil, with R. vitalii and H. canis. The piroplasm was observed on both blood smears and molecular tests. Many large piroplasms were detected inside the erythrocytes, with round, oval, or teardrop-shaped organism, that occurred singly or in pairs. They had an abundant, pale blue cytoplasm and decentral dark red small nucleus. The animal was also infected with H. canis that was detected only by molecular tests. The majority of haematological and biochemistry parameters were within the reference values for domestic dog and wild canids.

  9. A case report: a dog with acute onset of Hepatozoon canis infection.

    Science.gov (United States)

    Sakuma, Masato; Nakahara, Yoshitaka; Suzuki, Hiroyuki; Uchimura, Masato; Sekiya, Zin; Setoguchi, Asuka; Endo, Yasuyuki

    2009-06-01

    We present a clinical overview of a dog with acute onset of Hepatozoon canis infection. A stray female beagle dog of unknown age was referred to Kagoshima University showing anemia. Blood tests revealed the presence of anemia, thrombocytopenia, hyperproteinemia, polyclonal gammopathy, hypoalbuminemia, and elevated creatine kinase and alkaline phosphatase activities. In addition, capsule-like organisms were detected in the cytoplasm of approximately 50% of neutrophils in blood smears. H. canis infection was confirmed by polymerase chain reaction and DNA sequencing analyses. Amplified DNA fragments revealed 100% identity to the 18S ribosomal RNA gene of H. canis. The clinical symptoms improved after the administration of antibiotics. Hepatozoonosis in dogs is rare, but veterinarians should be alert to its possible acute onset.

  10. Establishment of Demodex canis on canine skin engrafted onto scid-beige mice.

    Science.gov (United States)

    Caswell, J L; Yager, J A; Barta, J R; Parker, W

    1996-12-01

    A small animal model of canine demodicosis is described. Normal canine skin was engrafted onto scid (severe combined immunodeficient)-beige mice, which lack functional B and T lymphocytes and have reduced natural killer cell activity. The xenografts were later infected with Demodex canis collected from a dog with demodicosis. At 30-112 days following infection, mites were seen histologically in the canine hair follicles of the engrafted skin. Demodex canis adults, nymphs, larvae, and eggs were present in samples macerated in sodium hydroxide. Mite infestations could not be demonstrated in the mouse skin, nor were mites passed from the infected graft to uninfected skin grafts on in-contact mice. This model may be utilized to assess the efficacy of miticidal treatments, to evaluate the importance of specific components of the immune response, and to study the biology of D. canis.

  11. Scanning electron microscopy description of a new species of Demodex canis spp.

    Science.gov (United States)

    Tamura, Y; Kawamura, Y; Inoue, I; Ishino, S

    2001-10-01

    Between 1997 and 1999, the prevalence of Demodex canis mites was determined in 150 dogs. In two dogs, we found two different species of mites; Demodex canis and another, unidentified, Demodex mite. The unidentified Demodex mite species had several different morphological features. First, it had a short opisthosoma and an obtuse end. In addition, the fourth coxisternal plate was rectangular and there was a band-like segmental plate between the fourth coxisternal plate and opisthosoma. Although all of the morphology and the development of male mites could not be investigated in this study, the location of the opisthosoma and the genital pore clearly differed from Demodex canis, suggesting that this unidentified mite is a new species.

  12. Konsentrasi Serum Anjing yang Optimum untuk Menumbuhkan dan Memelihara Babesia canis dalam Biakan

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    Tutuk Astyawati

    2010-12-01

    Full Text Available The use of cultivation system in vitro is very important in the future study of Babesia canis. Theaim of this study was to cultivate B. canis in vitro using RPMI media with different concentration of dogsera. B. canis infected erythrocytes were collected from splenectomized infected dog. Parasites werecultivated with RPMI 1640 medium supplemented with normal dog sera at the concentration of 10%, 20%and 40%, the culture were then incubated in 5% CO2 , 37oC temperature for 17 days and subcultured every48 hours. The Percentage of Parasitized Erythrocytes (PPE in culture with 10% dog serum was significantlylower than those 20%, and 40% The used of 20% and 40 % sera were better than 10%. It is recommendedthat 40 % serum can be used for initiation phase of cultivation, whereas 20% concentration were used formaintenance of the culture.

  13. Molecular and histopathological detection of Hepatozoon canis in red foxes (Vulpes vulpes) from Portugal.

    Science.gov (United States)

    Cardoso, Luís; Cortes, Helder C E; Eyal, Osnat; Reis, Antónia; Lopes, Ana Patrícia; Vila-Viçosa, Maria João; Rodrigues, Paula A; Baneth, Gad

    2014-03-24

    Hepatozoon canis is a protozoan tick-borne pathogen of dogs and wild canids. Hepatozoon spp. have been reported to infect foxes in different continents and recent studies have mostly used the polymerase chain reaction (PCR) for the detection and characterization of the infecting species. Surveying red foxes (Vulpes vulpes) may contribute to better understanding the epidemiology of canine vector-borne diseases, including hepatozoonosis caused by H. canis in domestic dogs. The present study investigated the prevalence of Hepatozoon spp. by means of histopathology and molecular analysis of different tissues in red foxes from different parts of Portugal. Blood and tissues including bone marrow, heart, hind leg muscle, jejunum, kidney, liver, lung, popliteal or axillary lymph nodes, spleen and/or tongue were collected from 91 red foxes from eight districts in northern, central and southern Portugal. Tissues were formalin-fixed, paraffin-embedded, cut and stained with hematoxylin and eosin. Polymerase chain reaction (PCR) amplified a ~650 bp fragment of the 18S rRNA gene of Hepatozoon spp. and the DNA products were sequenced. Hepatozoon canis was detected in 68 out of 90 foxes (75.6%) from all the sampled areas by PCR and sequencing. Histopathology revealed H. canis meronts similar in shape to those found in dogs in the bone marrow of 11 (23.4%) and in the spleen of two (4.3%) out of 47 foxes (p = 0.007). All the 11 foxes found positive by histopathology were also positive by PCR of bone marrow and/or blood. Positivity by PCR (83.0%) was significantly higher (p Hepatozoon canis was found to be highly prevalent in red fox populations from northern, central and southern Portugal. Detection of the parasite by histopathology was significantly less sensitive than by PCR. Red foxes are a presumptive reservoir of H. canis infection for domestic dogs.

  14. Neospora caninum and Ehrlichia canis co-infection in a dog with meningoencephalitis.

    Science.gov (United States)

    Aroch, Itamar; Baneth, Gad; Salant, Harold; Nachum-Biala, Yaarit; Berkowitz, Asaf; Shamir, Merav; Chai, Orit

    2018-06-01

    An 8-year-old mixed-breed dog was presented for acute, progressive weakness and ataxia, inappetence, and weight loss. The patient was mentally normal, but nonambulatory, with a right head tilt, right positional ventral strabismus, and slight head tremors. A neurologic lesion was localized to the cerebellum and right brainstem. Cerebrospinal fluid (CSF) analysis showed a markedly increased protein concentration and mixed pleocytosis, with eosinophil predominance (44%), intracytoplasmic inclusions within eosinophils, consistent with Ehrlichia canis (E canis) morulae, and Toxoplasma gondii (T gondii) or Neospora caninum (N caninum) tachyzoites within eosinophils and monocytes. A serum indirect immunofluorescent antibody test was positive for N caninum (titer 1:12 800) and negative for T gondii. Both blood and CSF PCR results were N caninum- and E canis-positive and T gondii- and Anaplasma phagocytophilum-negative, and blood PCR, but not CSF PCR, was Hepatozoon canis-positive. The dog was treated for 30 days with clindamycin, sulfamethoxazole-trimethoprim, doxycycline, prednisone, and cephalosporin, but did not improve neurologically, and was euthanized. Brain histopathology showed moderate multifocal, subacute meningoencephalitis with necrosis and gliosis. The neurologic disease was mostly attributed to central nervous system (CNS) neosporosis, with the possible contribution of ehrlichiosis, which was likely a manifestation of blood-brain barrier disruption. Hepatozoonosis was probably a result or cause of underlying immunosuppression. To our knowledge, this is the first report of CNSN caninum and E canis co-infection detected by both CSF PCR and cytology and E canis morulae identified within CSF eosinophils. © 2018 American Society for Veterinary Clinical Pathology.

  15. Toxocara canis, Trichinella spiralis and Taenia solium helminthozoonoses: seroprevalence among selected populations in north India.

    Science.gov (United States)

    Singh, B B; Sharma, R; Gill, J P S

    2015-09-01

    Helminthozoonoses are being considered as a research priority in India and many other tropical and subtropical countries. Taenia solium and Trichinella spiralis are emerging public health and food safety issues in the country and the developing world. The asymptomatic Ta. solium carriers act as important risk for neurocysticercosis, leading to adult onset epilepsy in the country. Human toxocariasis is another common zoonosis which occurs due to larvae of Toxocara canis or T. cati. The current study was planned to obtain baseline seropositivity data for Ta. solium, To. canis and Tr. spiralis antibodies among selected populations in Punjab province of northern India. In the present study, 122 human subjects belonging to selected occupations viz. farmers and veterinary practitioners were screened using the RIDASCREEN(®) Ta. solium IgG, RIDASCREEN(®) Toxocara IgG and RIDASCREEN(®) Trichinella IgG enzyme immunoassays for the qualitative determination of IgG antibodies against Ta. solium, Tr. spiralis and To. canis, respectively in human serum. The seropositivity of To. canis, Tr. spiralis and Ta. solium infections were found to be 22.13, 5.73 and 11.47 %, respectively in human serum samples. The relative risk of being infected for To. canis, Tr. spiralis and Ta. solium infections was found to be 1.91 (95 % CI 0.786-4.669), 2.61 (95 % CI 0.3258-20.94) and 1.596 (95 % CI 0.427-5.3893) times high respectively in farmers when compared to veterinary practitioners. The present study indicates that exposure to To. canis and Ta. solium is not uncommon among farmers and veterinary practitioners in this part of the country. These results provided evidence of Tr. spiralis among selected human populations in the country and demand more research related to trichinellosis in their respective animal and human hosts.

  16. Comparative Experimental Infection Study in Dogs with Ehrlichia canis, E. chaffeensis, Anaplasma platys and A. phagocytophilum.

    Science.gov (United States)

    Nair, Arathy D S; Cheng, Chuanmin; Ganta, Chanran K; Sanderson, Michael W; Alleman, Arthur R; Munderloh, Ulrike G; Ganta, Roman R

    2016-01-01

    Dogs acquire infections with the Anaplasmataceae family pathogens, E. canis, E. chaffeensis, E. ewingii, A. platys and A. phagocytophilum mostly during summer months when ticks are actively feeding on animals. These pathogens are also identified as causing diseases in people. Despite the long history of tick-borne diseases in dogs, much remains to be defined pertaining to the clinical and pathological outcomes of infections with these pathogens. In the current study, we performed experimental infections in dogs with E. canis, E. chaffeensis, A. platys and A. phagocytophilum. Animals were monitored for 42 days to evaluate infection-specific clinical, hematological and pathological differences. All four pathogens caused systemic persistent infections detectible throughout the 6 weeks of infection assessment. Fever was frequently detected in animals infected with E. canis, E. chaffeensis, and A. platys, but not in dogs infected with A. phagocytophilum. Hematological differences were evident in all four infected groups, although significant overlap existed between the groups. A marked reduction in packed cell volume that correlated with reduced erythrocytes and hemoglobin was observed only in E. canis infected animals. A decline in platelet numbers was common with E. canis, A. platys and A. phagocytophilum infections. Histopathological lesions in lung, liver and spleen were observed in all four groups of infected dogs; infection with E. canis had the highest pathological scores, followed by E. chaffeensis, then A. platys and A. phagocytophilum. All four pathogens induced IgG responses starting on day 7 post infection, which was predominantly comprised of IgG2 subclass antibodies. This is the first detailed investigation comparing the infection progression and host responses in dogs after inoculation with four pathogens belonging to the Anaplasmataceae family. The study revealed a significant overlap in clinical, hematological and pathological changes resulting from the

  17. Mortalidad por meningitis por Pasteurella canis. Oportunidades de aprendizaje

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    Ana Rosa Ropero Vera

    2016-01-01

    Full Text Available La meningitis bacteriana es una enfermedad importante de distribución mundial, causa mayor y sustancial de mortalidad y morbilidad en países en desarrollo. La Organización Mundial de la Salud (OMS sostiene que la meningitis es una de las diez afecciones principales del ser humano y debe ser considerada como una emergencia infectológica; por eso es fundamental reconocer que esta enfermedad es causa de muerte en niños de todo el mundo, sin distinción de raza, nivel económico o sociocultural. Se realizó una investigación de caso en menor de 53 días de nacido, que cumplía con los criterios clínicos y de laboratorio compatible con meningitis bacteriana, con el propósito de analizar y fortalecer la toma de decisiones en salud pública por parte de la secretaría local de salud del municipio de Valledupar (Colombia. Entre los hallazgos se encontró antecedentes infecciosos en el menor, coloración de Gram y cultivo de LCR, en el que se identificó cocobacilos Gram negativos, que fueron aislados como agente causal Pasteurella canis. Este estudio pretende sensibilizar a los prestadores de salud para que cuenten con personal altamente capacitado para brindar tratamientos adecuados y prevenir complicaciones en la meningitis bacteriana en niños, y así disminuir la posibilidad de secuelas o muerte, tanto en pacientes con compromiso inmunológico o sin este.

  18. Le primitif et le mystique chez Lévy-Bruhl, Bergson et Bataille.

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    Frédéric Keck

    2004-04-01

    Full Text Available L’assimilation du fou, du primitif et de l’enfant a été souvent analysée comme une opposition de l’archaïque par rapport au civilisé ou du normal par rapport au pathologique. On veut montrer ici que le mystique s’ajoute à cette liste, celle-ci désignant alors plutôt des figures de l’altérité qui défient la raison. On étudie alors les liens entre la figure du primitif et celle du mystique dans la sociologie de Lévy-Bruhl, la métaphysique de Bergson et la pratique littéraire de Bataille. Par-delà les divergences entre ces trois œuvres, on montre que le lien entre primitif et mystique vise à élargir le champ de l’expérience en l’ouvrant à une altérité radicale, et en même temps prépare le terrain pour cette expérience vide et formelle que pensera le structuralisme.French human sciences at the beginning of the 20th century used to assimilate the figures of the mad person, the primitive and the child. The Author shows that this assimilation should not be interpreted in the sense of an opposition between the archaic and the developed, or the normal and the pathological, but, once the figure of the mystic is added to this list, in the sense of an opposition between rationality and its other. Three examples allows to analyse the link between the figures of the primitive and the mystic : the sociology of Lévy-Bruhl, the metaphysics of Bergson, the literature of Bataille. Through the reading of these three works, the Author shows that the link between the figures of the primitive and the mystic allows to think a larger experience by opening it to an alterity, and at the same time prepares the ground for an empty and formal experience that will be explored by structuralism.

  19. Molecular detection of Hepatozoon canis and Babesia canis vogeli in domestic dogs from Cuiabá, Brazil Detecção molecular de Hepatozoon canis e Babesia canis vogeli em cães domésticos de Cuiabá, Brasil

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    Mariana Granziera Spolidorio

    2011-09-01

    Full Text Available The objective of this study was to report for the first time infection by Hepatozoon spp. and Babesia spp. in 10 dogs from the city of Cuiabá, State of Mato Grosso, central-western Brazil. A pair of primers that amplifies a 574 bp fragment of the 18S rRNA of Hepatozoon spp., and a pair of primers that amplifies a 551 bp fragment of the gene 18S rRNA for Babesia spp. were used. Six dogs were positive for Babesia spp., and 9 were positive for Hepatozoon spp. Co-infection of Babesia spp. and Hepatozoon spp. was seen in 5 dogs. Sequenced samples revealed 100% identity with B. canis vogeli, and H. canis. This is the first molecular detection of H. canis in domestic dogs from Cuiabá. Additionally, it is described for the first time the presence of B. canis vogeli circulating among dogs in Cuiabá.O objetivo deste estudo foi relatar pela primeira vez a infecção por Hepatozoon spp. e Babesia spp. em cães domésticos provenientes da cidade de Cuiabá, estado de Mato Grosso. Foram utilizados pares de primers que amplificam um fragmento de 574 pb do gene 18S rRNA de Hepatozoon spp., e 551 pb do gene 18S rRNA para Babesia spp. Dos 10 cães amostrados, 6 apresentaram-se positivos para Babesia spp., e 9 foram positivos para Hepatozoon spp. pela PCR. Co-infecção entre Babesia spp. e Hepatozoon spp. ocorreu em 5 cães. As amostras revelaram 100% de identidade com B. canis vogeli, e as amostras que foram positivas para Hepatozoon spp. foram 100% idênticas a H. canis. Esta é a primeira identificação molecular de H. canis em cães domésticos em Cuiabá. Adicionalmente, descrevemos pela primeira vez a presença de B. canis vogeli circulando entre cães em Cuiabá.

  20. Serum Zinc, Iron and Copper Concentrations in Dogs Infected with Hepatozoon canis

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    Kamil Seyrek

    2009-01-01

    Full Text Available In Turkey, canine hepatozoonosis is an emerging infection with a large number of cases detected during the past five years. In the present study, serum zinc, copper and iron concentrations of dogs infected with Hepatozoon canis were measured for the first time. Compared to the controls (n = 10, serum zinc and iron concentrations in infected animals (n = 14 decreased significantly (p p p Hepatozoon canis infection may cause alterations in serum zinc iron and copper concentrations. Furthermore, in the treatment of infected animals addition of zinc and iron to the ration of infected animals should be taken into consideration.

  1. A report of a Hepatozoon canis infection in a dog with transmissible venereal tumour

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    Namakkal Rajamanickam Senthil

    2015-10-01

    Full Text Available In the present study, a case of a Hepatozoan canis infection in a dog with a sexually transmissible venereal tumour is reported. Haematological examination revealed marked decrease in haemoglobin, PCV and RBC counts and the blood smear revealed rouleaux formation of RBC, hypochromasia, leptocytes and neutrophilia. Neutrophils were parasitized with both non-nucleated and stained nucleated forms of H. canis. Serum biochemistry results showed elevated levels of alkaline phosphatise, whereas blood urea nitrogen, creatinine, total protein, albumin and globulin were in the normal range.

  2. Morphometric variations in gametocytes of Hepatozoon canis from naturally infected dogs.

    Science.gov (United States)

    Eljadar, Mohamed S M; Singla, L D; Mustafa, Radya A A; Uppal, S K

    2013-04-01

    This study presents the morphometric characteristic of canine haemoprotozoan, Hepatozoon canis, using software DP2-BSW (OLYMPUS). The gametocytes of H. canis found inside the neutrophils were characteristic in shape and size and varied from 9.50 to 11.80 μm × 5.10-6.00 μm. Parasitaemia ranged from 1.00 to 39.00 %. Few gametocytes without nuclei and of abnormal shapes were also observed. The results were compared with the measurements done by using ocular micrometer.

  3. ELEVATED TRANS-MAMMARY TRANSMISSION OF Toxocara canis LARVAE IN BALB/c MICE

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    Paula de Lima Telmo

    2015-02-01

    Full Text Available Toxocariasis is a widespread zoonosis and is considered an important worldwide public health problem. The aim of this study was to investigate the frequency of trans-mammary Toxocara canis infection in newborn BALB/c mice nursed by females experimentally infected with 1,200 eggs after delivery. After 50 days of age, the presence of larvae in different organs of the offspring was investigated. Trans-mammary infection was confirmed in 73.9% of the mice that had been nursed by infected females. These data show a high trans-mammary transmission of T. canis and confirm the significance of this transmission route in paratenic hosts.

  4. Ehrlichia canis morulae and DNA detection in whole blood and spleen aspiration samples.

    Science.gov (United States)

    Faria, Joice Lara Maia; Dagnone, Ana Sílvia; Munhoz, Thiago Demarchi; João, Carolina Franchi; Pereira, Wanderson Adriano Biscola; Machado, Rosângela Zacarias; Tinucci-Costa, Mirela

    2010-01-01

    The aim of this study was to compare the detection of Ehrlichia canis morulae and DNA by nPCR in whole blood and spleen aspiration. The sample included 40 dogs showing thrombocytopenia associated to clinical signs suggestive of canine ehrlichiosis. Morulae detection showed that in 35 of the dogs studied, 17 had morulae in spleen tissue, and two in buffy coat smears. E. canis DNA was detected in 29/40 blood samples. We verified that morulae detection is more efficient in cytological preparations from spleen aspiration. On the other hand, nPCR on spleen and blood samples were equally efficient for disease diagnosis.

  5. Serology, molecular detection and risk factors of Ehrlichia canis infection in dogs in Costa Rica.

    Science.gov (United States)

    Barrantes-González, Alexander V; Jiménez-Rocha, Ana E; Romero-Zuñiga, Juan José; Dolz, Gaby

    2016-10-01

    A cross-sectional study combining different serological and molecular techniques for the detection of Ehrlichia species in dogs and their ticks was carried out with data from all regions of Costa Rica. A seroprevalence of 32.1% (131/408), and infection with E. canis of 3.2% (13/407) was found, whereas 6.9% (9/130) of ticks attached to the dogs were PCR positive to E. canis. Higher prevalences were found outside the Greater Metropolitan Area (GMA). Risk factors associated with E. canis seropositivity were age, between 2 and 7 years (RR: 1.6, 95% CI: 1.2-2.2) and 8-15 years (RR: 1.8, 95% CI: 1.2-3.0), number of dogs/total of households [Dogs per Household Ratio (DHR) ≥3.1 (RR: 2.0; 95% CI: 1.4-3.0)], number of dogs infested with at least one tick/total of dogs sampled [Tick Infestation Prevalence (TIP)≥31% (RR: 2.1; 95% CI:1.3-3.3)] and living outside the GMA (RR: 1.7; 95% CI: 1.2-2.4) and being a mixed-breed dog (RR: 1.5; 95% CI: 1.1-2.1). Risk factors for E. canis PCR positive dogs were a depressive attitude (OR: 11.2; 95% CI: 1.1-115.9), fever (OR:4.8; 95% CI:1.2-19.3), DHR≥3.1 (OR: 5.7; 95% CI:1.7-19.2)], number of ticks/total of dogs sampled [Tick Distribution Ratio (TDR) ≥2.1 (OR: 6.5; 95% CI: 1.3-31.8)], and TIP≥40% (OR: 5.7; 95% CI: 1.7-19.2). This paper describes E. canis seroprevalence, PCR prevalence and tick analysis in dogs from Costa Rica, with associated clinical signs and owner perceptions. In summary, most of the E. canis infections in dogs in our country seemed to pass unnoticed by owners. Since most of the seropositive dogs (97.7%, 131/134) were negative for E. canis DNA in their blood, it is important to determine in future studies if these dogs recovered from the E. canis infection without any medication, or are persistently infected, and will develop chronic disease. Copyright © 2016 Elsevier GmbH. All rights reserved.

  6. Prevalence of Toxocara canis infection in dogs in the Warszawa area.

    Science.gov (United States)

    Borecka, A; Gawor, J

    2000-01-01

    The evaluation of Toxocara canis infection in stray dogs from two shelters and private owners dogs in the Warszawa district was the aim of this study. In 1998 five hundred faecal samples were examined. The homeless dogs were found more infected than those kept as pets. T. canis was recorded in 3.4% and 8.8% of stray dogs from the shelters and in 0.4% of animals from flats. The higher prevalence of infection in homeless dogs was due to high density of dogs population, worse environmental condition and irregular anthelmintic treatment in the shelters when compare with housed dogs.

  7. Serological cross-reactivity of Trypanosoma cruzi, Ehrlichia canis, Toxoplasma gondii, Neospora caninum and Babesia canis to Leishmania infantum chagasi tests in dogs

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    Maurício Franco Zanette

    2014-01-01

    Full Text Available Introduction: The aim of this study was to evaluate the serological cross-reactivity between Leishmania sp. and other canine pathogens. Methods: Positive serum samples for Ehrlichia canis, Babesia canis, Toxoplasma gondii, Neospora caninum and Trypanosoma cruzi were tested using three serological methods enzyme linked immunosorbent assay (ELISA, indirect immunofluorescent antibody test (IFAT and Kalazar Detect™, for canine visceral leishmaniasis. Results: Of the 57 dog samples tested, 24 (42.1% tested positive using one of the three serological methods: 10/57 (17.5% for ELISA, 11/57 (19.3% for IFAT and 3/57 (5.3% for Kalazar Detect™. Conclusions: Our results demonstrated that the presence of other infectious agents may lead to cross-reactivity on leishmaniasis serological tests.

  8. Canis mtDNA HV1 database: a web-based tool for collecting and surveying Canis mtDNA HV1 haplotype in public database.

    Science.gov (United States)

    Thai, Quan Ke; Chung, Dung Anh; Tran, Hoang-Dung

    2017-06-26

    Canine and wolf mitochondrial DNA haplotypes, which can be used for forensic or phylogenetic analyses, have been defined in various schemes depending on the region analyzed. In recent studies, the 582 bp fragment of the HV1 region is most commonly used. 317 different canine HV1 haplotypes have been reported in the rapidly growing public database GenBank. These reported haplotypes contain several inconsistencies in their haplotype information. To overcome this issue, we have developed a Canis mtDNA HV1 database. This database collects data on the HV1 582 bp region in dog mitochondrial DNA from the GenBank to screen and correct the inconsistencies. It also supports users in detection of new novel mutation profiles and assignment of new haplotypes. The Canis mtDNA HV1 database (CHD) contains 5567 nucleotide entries originating from 15 subspecies in the species Canis lupus. Of these entries, 3646 were haplotypes and grouped into 804 distinct sequences. 319 sequences were recognized as previously assigned haplotypes, while the remaining 485 sequences had new mutation profiles and were marked as new haplotype candidates awaiting further analysis for haplotype assignment. Of the 3646 nucleotide entries, only 414 were annotated with correct haplotype information, while 3232 had insufficient or lacked haplotype information and were corrected or modified before storing in the CHD. The CHD can be accessed at http://chd.vnbiology.com . It provides sequences, haplotype information, and a web-based tool for mtDNA HV1 haplotyping. The CHD is updated monthly and supplies all data for download. The Canis mtDNA HV1 database contains information about canine mitochondrial DNA HV1 sequences with reconciled annotation. It serves as a tool for detection of inconsistencies in GenBank and helps identifying new HV1 haplotypes. Thus, it supports the scientific community in naming new HV1 haplotypes and to reconcile existing annotation of HV1 582 bp sequences.

  9. Modeling and complexity of stochastic interacting Lévy type financial price dynamics

    Science.gov (United States)

    Wang, Yiduan; Zheng, Shenzhou; Zhang, Wei; Wang, Jun; Wang, Guochao

    2018-06-01

    In attempt to reproduce and investigate nonlinear dynamics of security markets, a novel nonlinear random interacting price dynamics, which is considered as a Lévy type process, is developed and investigated by the combination of lattice oriented percolation and Potts dynamics, which concerns with the instinctive random fluctuation and the fluctuation caused by the spread of the investors' trading attitudes, respectively. To better understand the fluctuation complexity properties of the proposed model, the complexity analyses of random logarithmic price return and corresponding volatility series are preformed, including power-law distribution, Lempel-Ziv complexity and fractional sample entropy. In order to verify the rationality of the proposed model, the corresponding studies of actual security market datasets are also implemented for comparison. The empirical results reveal that this financial price model can reproduce some important complexity features of actual security markets to some extent. The complexity of returns decreases with the increase of parameters γ1 and β respectively, furthermore, the volatility series exhibit lower complexity than the return series

  10. How superdiffusion gets arrested: ecological encounters explain shift from Lévy to Brownian movement.

    Science.gov (United States)

    de Jager, Monique; Bartumeus, Frederic; Kölzsch, Andrea; Weissing, Franz J; Hengeveld, Geerten M; Nolet, Bart A; Herman, Peter M J; van de Koppel, Johan

    2014-01-07

    Ecological theory uses Brownian motion as a default template for describing ecological movement, despite limited mechanistic underpinning. The generality of Brownian motion has recently been challenged by empirical studies that highlight alternative movement patterns of animals, especially when foraging in resource-poor environments. Yet, empirical studies reveal animals moving in a Brownian fashion when resources are abundant. We demonstrate that Einstein's original theory of collision-induced Brownian motion in physics provides a parsimonious, mechanistic explanation for these observations. Here, Brownian motion results from frequent encounters between organisms in dense environments. In density-controlled experiments, movement patterns of mussels shifted from Lévy towards Brownian motion with increasing density. When the analysis was restricted to moves not truncated by encounters, this shift did not occur. Using a theoretical argument, we explain that any movement pattern approximates Brownian motion at high-resource densities, provided that movement is interrupted upon encounters. Hence, the observed shift to Brownian motion does not indicate a density-dependent change in movement strategy but rather results from frequent collisions. Our results emphasize the need for a more mechanistic use of Brownian motion in ecology, highlighting that especially in rich environments, Brownian motion emerges from ecological interactions, rather than being a default movement pattern.

  11. vy flight with absorption: A model for diffusing diffusivity with long tails

    Science.gov (United States)

    Jain, Rohit; Sebastian, K. L.

    2017-03-01

    We consider diffusion of a particle in rearranging environment, so that the diffusivity of the particle is a stochastic function of time. In our previous model of "diffusing diffusivity" [Jain and Sebastian, J. Phys. Chem. B 120, 3988 (2016), 10.1021/acs.jpcb.6b01527], it was shown that the mean square displacement of particle remains Fickian, i.e., ∝T at all times, but the probability distribution of particle displacement is not Gaussian at all times. It is exponential at short times and crosses over to become Gaussian only in a large time limit in the case where the distribution of D in that model has a steady state limit which is exponential, i.e., πe(D ) ˜e-D /D0 . In the present study, we model the diffusivity of a particle as a Lévy flight process so that D has a power-law tailed distribution, viz., πe(D ) ˜D-1 -α with 0 <α <1 . We find that in the short time limit, the width of displacement distribution is proportional to √{T }, implying that the diffusion is Fickian. But for long times, the width is proportional to T1 /2 α which is a characteristic of anomalous diffusion. The distribution function for the displacement of the particle is found to be a symmetric stable distribution with a stability index 2 α which preserves its shape at all times.

  12. How superdiffusion gets arrested: ecological encounters explain shift from Lévy to Brownian movement

    Science.gov (United States)

    de Jager, Monique; Bartumeus, Frederic; Kölzsch, Andrea; Weissing, Franz J.; Hengeveld, Geerten M.; Nolet, Bart A.; Herman, Peter M. J.; van de Koppel, Johan

    2014-01-01

    Ecological theory uses Brownian motion as a default template for describing ecological movement, despite limited mechanistic underpinning. The generality of Brownian motion has recently been challenged by empirical studies that highlight alternative movement patterns of animals, especially when foraging in resource-poor environments. Yet, empirical studies reveal animals moving in a Brownian fashion when resources are abundant. We demonstrate that Einstein's original theory of collision-induced Brownian motion in physics provides a parsimonious, mechanistic explanation for these observations. Here, Brownian motion results from frequent encounters between organisms in dense environments. In density-controlled experiments, movement patterns of mussels shifted from Lévy towards Brownian motion with increasing density. When the analysis was restricted to moves not truncated by encounters, this shift did not occur. Using a theoretical argument, we explain that any movement pattern approximates Brownian motion at high-resource densities, provided that movement is interrupted upon encounters. Hence, the observed shift to Brownian motion does not indicate a density-dependent change in movement strategy but rather results from frequent collisions. Our results emphasize the need for a more mechanistic use of Brownian motion in ecology, highlighting that especially in rich environments, Brownian motion emerges from ecological interactions, rather than being a default movement pattern. PMID:24225464

  13. Combined V-Y Fasciocutaneous Advancement and Gluteus Maximus Muscle Rotational Flaps for Treating Sacral Sores

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    Hyun Ho Han

    2016-01-01

    Full Text Available The sacral area is the most common site of pressure sore in bed-ridden patients. Though many treatment methods have been proposed, a musculocutaneous flap using the gluteus muscles or a fasciocutaneous flap is the most popular surgical option. Here, we propose a new method that combines the benefits of these 2 methods: combined V-Y fasciocutaneous advancement and gluteus maximus muscle rotational flaps. A retrospective review was performed for 13 patients who underwent this new procedure from March 2011 to December 2013. Patients’ age, sex, accompanying diseases, follow-up duration, surgical details, complications, and recurrence were documented. Computed tomography was performed postoperatively at 2 to 4 weeks and again at 4 to 6 months to identify the thickness and volume of the rotational muscle portion. After surgery, all patients healed within 1 month; 3 patients experienced minor complications. The average follow-up period was 13.6 months, during which time 1 patient had a recurrence (recurrence rate, 7.7%. Average thickness of the rotated muscle was 9.43 mm at 2 to 4 weeks postoperatively and 9.22 mm at 4 to 6 months postoperatively (p=0.087. Muscle thickness had not decreased, and muscle volume was relatively maintained. This modified method is relatively simple and easy for reconstructing sacral sores, provides sufficient padding, and has little muscle donor-site morbidity.

  14. Record statistics of a strongly correlated time series: random walks and Lévy flights

    Science.gov (United States)

    Godrèche, Claude; Majumdar, Satya N.; Schehr, Grégory

    2017-08-01

    We review recent advances on the record statistics of strongly correlated time series, whose entries denote the positions of a random walk or a Lévy flight on a line. After a brief survey of the theory of records for independent and identically distributed random variables, we focus on random walks. During the last few years, it was indeed realized that random walks are a very useful ‘laboratory’ to test the effects of correlations on the record statistics. We start with the simple one-dimensional random walk with symmetric jumps (both continuous and discrete) and discuss in detail the statistics of the number of records, as well as of the ages of the records, i.e. the lapses of time between two successive record breaking events. Then we review the results that were obtained for a wide variety of random walk models, including random walks with a linear drift, continuous time random walks, constrained random walks (like the random walk bridge) and the case of multiple independent random walkers. Finally, we discuss further observables related to records, like the record increments, as well as some questions raised by physical applications of record statistics, like the effects of measurement error and noise.

  15. Modified Bat Algorithm Based on Lévy Flight and Opposition Based Learning

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    Xian Shan

    2016-01-01

    Full Text Available Bat Algorithm (BA is a swarm intelligence algorithm which has been intensively applied to solve academic and real life optimization problems. However, due to the lack of good balance between exploration and exploitation, BA sometimes fails at finding global optimum and is easily trapped into local optima. In order to overcome the premature problem and improve the local searching ability of Bat Algorithm for optimization problems, we propose an improved BA called OBMLBA. In the proposed algorithm, a modified search equation with more useful information from the search experiences is introduced to generate a candidate solution, and Lévy Flight random walk is incorporated with BA in order to avoid being trapped into local optima. Furthermore, the concept of opposition based learning (OBL is embedded to BA to enhance the diversity and convergence capability. To evaluate the performance of the proposed approach, 16 benchmark functions have been employed. The results obtained by the experiments demonstrate the effectiveness and efficiency of OBMLBA for global optimization problems. Comparisons with some other BA variants and other state-of-the-art algorithms have shown the proposed approach significantly improves the performance of BA. Performances of the proposed algorithm on large scale optimization problems and real world optimization problems are not discussed in the paper, and it will be studied in the future work.

  16. SPDEs with α-Stable Lévy Noise: A Random Field Approach

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    Raluca M. Balan

    2014-01-01

    Full Text Available This paper is dedicated to the study of a nonlinear SPDE on a bounded domain in Rd, with zero initial conditions and Dirichlet boundary, driven by an α-stable Lévy noise Z with α∈(0,2, α≠1, and possibly nonsymmetric tails. To give a meaning to the concept of solution, we develop a theory of stochastic integration with respect to this noise. The idea is to first solve the equation with “truncated” noise (obtained by removing from Z the jumps which exceed a fixed value K, yielding a solution uK, and then show that the solutions uL,L>K coincide on the event t≤τK, for some stopping times τK converging to infinity. A similar idea was used in the setting of Hilbert-space valued processes. A major step is to show that the stochastic integral with respect to ZK satisfies a pth moment inequality. This inequality plays the same role as the Burkholder-Davis-Gundy inequality in the theory of integration with respect to continuous martingales.

  17. Diffusion approximation of Lévy processes with a view towards finance

    KAUST Repository

    Kiessling, Jonas; Tempone, Raul

    2011-01-01

    Let the (log-)prices of a collection of securities be given by a d-dimensional Lévy process X t having infinite activity and a smooth density. The value of a European contract with payoff g(x) maturing at T is determined by E[g(X T)]. Let X̄ T be a finite activity approximation to X T, where diffusion is introduced to approximate jumps smaller than a given truncation level ∈ > 0. The main result of this work is a derivation of an error expansion for the resulting model error, E[g(X T) - g(X̄ T)], with computable leading order term. Our estimate depends both on the choice of truncation level ∈ and the contract payoff g, and it is valid even when g is not continuous. Numerical experiments confirm that the error estimate is indeed a good approximation of the model error. Using similar techniques we indicate how to construct an adaptive truncation type approximation. Numerical experiments indicate that a substantial amount of work is to be gained from such adaptive approximation. Finally, we extend the previous model error estimates to the case of Barrier options, which have a particular path dependent structure. © de Gruyter 2011.

  18. Prognostics-based qualification of high-power white LEDs using Lévy process approach

    Science.gov (United States)

    Yung, Kam-Chuen; Sun, Bo; Jiang, Xiaopeng

    2017-01-01

    Due to their versatility in a variety of applications and the growing market demand, high-power white light-emitting diodes (LEDs) have attracted considerable attention. Reliability qualification testing is an essential part of the product development process to ensure the reliability of a new LED product before its release. However, the widely used IES-TM-21 method does not provide comprehensive reliability information. For more accurate and effective qualification, this paper presents a novel method based on prognostics techniques. Prognostics is an engineering technology predicting the future reliability or determining the remaining useful lifetime (RUL) of a product by assessing the extent of deviation or degradation from its expected normal operating conditions. A Lévy subordinator of a mixed Gamma and compound Poisson process is used to describe the actual degradation process of LEDs characterized by random sporadic small jumps of degradation degree, and the reliability function is derived for qualification with different distribution forms of jump sizes. The IES LM-80 test results reported by different LED vendors are used to develop and validate the qualification methodology. This study will be helpful for LED manufacturers to reduce the total test time and cost required to qualify the reliability of an LED product.

  19. A PARASITOLOGIC AND MOLECULAR SURVEY OF HEPATOZOON CANIS INFECTION IN STRAY DOGS IN NORTHEAST OF IRAN.

    Science.gov (United States)

    Barati, Ali; Razmi, Gholamreza

    2018-05-15

    Canine hepatozoonosis, caused by H. canis, is a tick-borne disease in domestic and wild dogs that is transmitted by ingestion of Rhipicephalus sanguineus ticks. The aim of the study was to detect H. canis in stray dogs in Iran using blood smear examination and molecular techniques. From October 2014 to September 2015, 150 EDTA blood samples were collected from stray dogs in the northeast region of Iran. Blood smears were microscopically examined for the presence of Hepatozoon gamonts; whole blood was evaluated by PCR, with subsequent sequencing and phylogenetic analysis. Hepatozoon spp. Gamonts were observed in the neutrophils of 5/150 (3.3%) blood smears, whereas Hepatozoon spp. 18S rDNA was detected in 12/150 (8.0%) blood samples from stray dogs. There was a good agreement between microscopy and PCR methods. (Kappa= 0.756). The highest rate of infection was seasonally detected in the summer (pHepatozoon spp infection was not significant by gender and age factors (p>0.05). The alignment analysis of the sequenced samples showed ≥99% similarity with other nucleotide sequences of Hepatozoon spp. in GenBank. The phylogenetic tree also revealed that the nucleotide sequences in this study were clustered in the H. canis clade and different from the H. felis and H. americanum clades. According to the results, it is concluded that H. canis infection is present among dogs in northeastern region of Iran.

  20. Molecular Survey of Hepatozoon canis in Red Foxes (Vulpes vulpes) from Romania.

    Science.gov (United States)

    Imre, Mirela; Dudu, Andreea; Ilie, Marius S; Morariu, Sorin; Imre, Kálmán; Dărăbuş, Gheorghe

    2015-08-01

    Blood samples of 119 red foxes, originating from 44 hunting grounds of 3 western counties (Arad, Hunedoara, and Timiş) of Romania, have been examined for the presence of Hepatozoon canis infection using the conventional polymerase chain reaction (PCR) of the fragment of 18S rRNA gene. Overall, 15 (12.6%) samples were found to be PCR-positive. Of the sampled hunting grounds, 29.5% (13/44) were found positive. Positive samples were recorded in all screened counties with the prevalence of 14.8% (9/61) in Arad, 9.8% (5/51) in Timiş, and 14.3% (1/7) in Hunedoara, respectively. No correlation was found (P > 0.05) between H. canis positivity and gender or territorial distribution of the infection. To confirm PCR results, 9 randomly selected amplicons were sequenced. The obtained sequences were identical to each other, confirmed the results of the conventional PCR, and showed 98-100% homology to other H. canis sequences. The results of the current survey support the role of red foxes as sylvatic reservoirs of H. canis in Romania.

  1. Failure of imidocarb dipropionate and toltrazuril/emodepside plus clindamycin in treating Hepatozoon canis infection.

    Science.gov (United States)

    De Tommasi, Anna Sara; Giannelli, Alessio; de Caprariis, Donato; Ramos, Rafael Antonio Nascimento; Di Paola, Giancarlo; Crescenzo, Giuseppe; Dantas-Torres, Filipe; Baneth, Gad; Otranto, Domenico

    2014-03-01

    Hepatozoonosis caused by Hepatozoon canis (Eucoccidiorida, Hepatozoidae) is among the most widespread vector-borne infections of dogs, primarily transmitted by Rhipicephalus sanguineus sensu lato ticks. Based on the absence of a consensus on the treatment regimes for canine hepatozoonosis, the present study aimed to evaluate the efficacy of imidocarb dipropionate (5-6 mg/kg subcutaneously once a week for 6 weeks), and of toltrazuril/emodepside (Procox(®), 15 mg/kg once a day for 6 days) in association with clindamycin (15 mg/kg once a day for 21 days) in treating naturally infected dogs. At the enrollment time (T0), 32 dogs, cytologically or molecularly positive for H. canis, were assigned to test and control groups. Animals were treated according to the specific therapeutic protocol, and the presence of H. canis gamonts was assessed weekly by cytology and PCR throughout six months (T1-T19). In addition, any abnormality in leucocyte morphology was evaluated and recorded. Results indicate that, in spite of a reduction in the percentage of infected dogs, both treatments did not provide parasitological cure. Accordingly, new treatment protocols or active compounds against H. canis should be investigated. Copyright © 2013 Elsevier B.V. All rights reserved.

  2. Hepatozoon canis infection in ticks during spring and summer in Italy.

    Science.gov (United States)

    Dantas-Torres, Filipe; Latrofa, Maria Stefania; Weigl, Stefania; Tarallo, Viviana Domenica; Lia, Riccardo Paolo; Otranto, Domenico

    2012-02-01

    Hepatozoon canis is a common protozoan of dogs, being among the most prevalent tick-borne pathogens infecting dogs around the world. It is primarily transmitted by Rhipicephalus sanguineus, the brown dog tick. In this study we tested ticks collected from dogs and from the environment in order to track the origin of an outbreak of H. canis infection detected in October 2009 in a private dog shelter in southern Italy. Ticks from dogs (n = 267) were collected during the spring of 2009, whereas ticks from environment (n = 300) were found on sticky traps placed in the same shelter during the summer of 2009. All ticks were tested by PCR for the detection of a H. canis 18S ribosomal RNA gene fragment. Four (1.5%, one female and three males) ticks collected from dogs were PCR positive. None of the larvae collected from the environment were positive, but a relatively high infection rate (8.0%) was detected in nymphs. These findings point out that dogs became infected during the summer, when ticks were abundant and highly infected by H. canis. Moreover, this study suggests that castor oil sticky traps might be useful to collect engorged immature ticks in highly infested environments (e.g., dog shelters). This might be particularly interesting to evaluate the level of infection by certain pathogens in free-ranging ticks R. sanguineus, as done in the present study.

  3. Molecular epidemiology of parasitic protozoa and Ehrlichia canis in wildlife in Madrid (central Spain).

    Science.gov (United States)

    Criado-Fornelio, Angel; Martín-Pérez, T; Verdú-Expósito, C; Reinoso-Ortiz, S A; Pérez-Serrano, J

    2018-07-01

    Wildlife species are involved in the transmission of diverse pathogens. This study aimed to monitor raccoons (Procyon lotor), American minks (Neovison vison), and red foxes (Vulpes vulpes) as potential reservoirs in central Spain. Specifically, 200 spleen and fecal samples (from 194 raccoons, 3 minks, and 3 foxes) were analyzed molecularly by PCR/qPCR and sequencing for the presence of piroplasmids, Hepatozoon spp., Toxoplasma gondii, and Ehrlichia canis infections in the Community of Madrid (Spain). Biological samples were obtained in the years 2014, 2015, and 2016. No pathogen DNA was found in fecal samples. In contrast, analysis of raccoon spleen samples revealed that Toxoplasma was the most prevalent pathogen (prevalence 3.6 ± 2.6%), followed by Hepatozoon canis and E. canis (each with a prevalence of 2.57 ± 2.2%). Hepatozoon canis was also diagnosed in all three of the analyzed foxes. Analysis of yearly prevalence showed that tick-borne pathogens were less frequent in raccoon in 2015, a dry and warm year compared both to 2014 and 2016. These data suggest that fecal PCR assays are unsuitable for detection of DNA of non-erythrocytic pathogens. Furthermore, they demonstrate that the raccoon (an invasive species often living in proximity to domestic areas) and the red fox are putative reservoirs for pathogenic organisms in the Community of Madrid.

  4. Development of a real-time PCR to detect Demodex canis DNA in different tissue samples.

    Science.gov (United States)

    Ravera, Ivan; Altet, Laura; Francino, Olga; Bardagí, Mar; Sánchez, Armand; Ferrer, Lluís

    2011-02-01

    The present study reports the development of a real-time polymerase chain reaction (PCR) to detect Demodex canis DNA on different tissue samples. The technique amplifies a 166 bp of D. canis chitin synthase gene (AB 080667) and it has been successfully tested on hairs extracted with their roots and on formalin-fixed paraffin embedded skin biopsies. The real-time PCR amplified on the hairs of all 14 dogs with a firm diagnosis of demodicosis and consistently failed to amplify on negative controls. Eleven of 12 skin biopsies with a morphologic diagnosis of canine demodicosis were also positive. Sampling hairs on two skin points (lateral face and interdigital skin), D. canis DNA was detected on nine of 51 healthy dogs (17.6%) a much higher percentage than previously reported with microscopic studies. Furthermore, it is foreseen that if the number of samples were increased, the percentage of positive dogs would probably also grow. Moreover, in four of the six dogs with demodicosis, the samples taken from non-lesioned skin were positive. This finding, if confirmed in further studies, suggests that demodicosis is a generalized phenomenon in canine skin, due to proliferation of local mite populations, even though macroscopic lesions only appear in certain areas. The real-time PCR technique to detect D. canis DNA described in this work is a useful tool to advance our understanding of canine demodicosis.

  5. First phylogenetic analysis of Ehrlichia canis in dogs and ticks from Mexico. Preliminary study

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    Carolina G. Sosa-Gutiérrez

    2016-09-01

    Full Text Available Objective. Phylogenetic characterization of Ehrlichia canis in dogs naturally infected and ticks, diagnosed by PCR and sequencing of 16SrRNA gene; compare different isolates found in American countries. Materials and methods. Were collected Blood samples from 139 dogs with suggestive clinical manifestations of this disease and they were infested with ticks; part of 16SrRNA gene was sequenced and aligned, with 17 sequences reported in American countries. Two phylogenetic trees were constructed using the Maximum likelihood method, and Maximum parsimony. Results. They were positive to E. canis 25/139 (18.0% dogs and 29/139 (20.9% ticks. The clinical manifestations presented were fever, fatigue, depression and vomiting. Rhipicephalus sanguineus Dermacentor variabilis and Haemaphysalis leporis-palustris ticks were positive for E. canis. Phylogenetic analysis showed that the sequences of dogs and ticks in Mexico form a third group diverging of sequences from South America and USA. Conclusions. This is the first phylogenetic analysis of E. canis in Mexico. There are differences in the sequences of Mexico with those reported in South America and USA. This research lays the foundation for further study of genetic variability.

  6. Gray wolf (Canis lupus) is a natural definitive host for Neospora caninum

    Science.gov (United States)

    The gray wolf (Canis lupus) was found to be a new natural definitive host for Neospora caninum. This finding is based on the recovery of Neospora-like oocysts from the feces of 3 of 73 wolves from Minnesota examined at necropsy, and on successful amplification of N. caninum-specific sequences from ...

  7. Hair Contamination of Sheepdog and Pet Dogs with Toxocara Canis Eggs

    Directory of Open Access Journals (Sweden)

    AR Khezri

    2012-12-01

    Full Text Available Background: We tried to investigate the hair contamination of pet dogs and farm sheepdog with Toxocara eggs in terms of the different sex and age groups in north-west of Iran (Urmia and its sub­urbs.Methods: Hair samples were collected from a total of 138 pet and farm sheepdogs from November 2008 to June 2009 in Urmia City and the suburb (West Azerbaijan-Iran and examined for the pres­ence of T. canis eggs.Results: T. canis eggs found in 60 samples altogether (pet and shepherd dogs showed a contamina­tion rate of 36.2%. The number of observed T. canis eggs in each microscope field was va­ried from 1 to > 400. The age of the dog was found a significant factor to influence the prevalence and intensity of contamination, with 82% of all the eggs recovered from puppies (six months and younger. Additionally, the numbers of eggs in farm sheepdogs were significantly higher than pet dogs (P<0.05.Conclusions: This report shows that direct contact with T. canis infected dogs, particularly puppies from shepherd dogs, may pose a serious hazard to human. Besides, as they may harbor a considera­ble number of eggs on their hair, they can contaminate the soil and the environment.

  8. 75 FR 24741 - Endangered and Threatened Wildlife and Plants; Mexican Wolf (Canis lupus baileyi) Conservation...

    Science.gov (United States)

    2010-05-05

    ...] Endangered and Threatened Wildlife and Plants; Mexican Wolf (Canis lupus baileyi) Conservation Assessment... Mexico Ecological Services Field Office, 2105 Osuna NE, Albuquerque, NM 87113; by telephone at 505-761... guided by the 1982 Mexican Wolf Recovery Plan (U.S. Fish and Wildlife Service 1982) (recovery plan...

  9. Isolation and genetic characterization of Toxoplasma gondii from the gray wolf Canis lupus

    Science.gov (United States)

    Little is known of the genetic diversity of Toxoplasma gondii circulating in wildlife. In the present study feral gray wolf (Canis lupus) from Minnesota were examined for T. gondii infection. Antibodies to T. gondii were detected in 130 (52.4%) of 248 wolves tested by the modified agglutination test...

  10. Sarcocystis arctica (Apicomplexa: Sarcocystidae): ultrastructural description and its new host record, the Alaskan wolf (Canis lupus

    Science.gov (United States)

    Sarcocystis sarcocysts are common in muscles of herbivores but are rare in muscles of carnivores. Here, we report sarcocysts in muscle of an Alaskan wolf (Canis lupus) from Alaska, USA for the first time. Sarcocysts extracted from tongue of the wolf were up to 900 µm long, slender, and appeared to h...

  11. Tissue expression pattern of ABCG transporter indicates functional roles in reproduction of Toxocara canis.

    Science.gov (United States)

    Luo, Yong-Li; Ma, Guang-Xu; Luo, Yong-Fang; Kuang, Ce-Yan; Jiang, Ai-Yun; Li, Guo-Qing; Zhou, Rong-Qiong

    2018-03-01

    Toxocara canis is a zoonotic parasite with worldwide distribution. ATP-binding cassette (ABC) transporters are integral membrane proteins which involve in a range of biological processes in various organisms. In present study, the full-length coding sequence of abcg-5 gene of T. canis (Tc-abcg-5) was cloned and characterized. A 633 aa polypeptide containing two conserved Walker A and Walker B motifs was predicted from a continuous 1902 nt open reading frame. Quantitative real-time PCR was employed to determine the transcriptional levels of Tc-abcg-5 gene in adult male and female worms, which indicated high mRNA level of Tc-abcg-5 in the reproductive tract of adult female T. canis. Tc-abcg-5 was expressed to produce rabbit polyclonal antiserum against recombinant TcABCG5. Indirect-fluorescence immunohistochemical assays were carried out to detect the tissue distribution of TcABCG5, which showed predominant distribution of TcABCG5 in the uterus (especially in the germ cells) of adult female T. canis. Tissue transcription and expression pattern of Tc-abcg-5 indicated that Tc-abcg-5 might play essential roles in the reproduction of this parasitic nematode.

  12. Tissue distribution and functional analysis of vitellogenin-6 of Toxocara canis.

    Science.gov (United States)

    Zhu, Hong-Hong; Ma, Guang-Xu; Luo, Yong-Fang; Luo, Yong-Li; Yin, Sha-Sha; Xiong, Yi; Zhou, Rong-Qiong

    2017-06-01

    Toxocara canis is an common intestinal nematode of canids and the principal causative agent of human toxocariasis. Vitellogenin (Vg), a source of amino acids and lipids in the eggs, are considered to play an important role in embryo development of a wide range of organisms. In the present study, the transcriptional levels of Tc-vit-6 gene in male and female adult T. canis were determined by quantitative real-time PCR, which indicated high transcription of Tc-vit-6 in the intestine, reproductive tract and body wall of male and female adult T. canis. The fragment of Tc-vit-6 encoding a vWD domain, was cloned and expressed to produce a rabbit anti-TcvWD polyclonal antibody. Tissue distribution of TcVg6 was detected by immunohistochemical assays, which showed predominant distribution of TcVg6 in the tissues of intestine, as well as reproductive tract (including some of the germ cells) and musculature of male and female adult worms. Collectively, these results indicated multiple biological roles of TcVg6 apart from that in the reproduction of T. canis. Copyright © 2017 Elsevier Inc. All rights reserved.

  13. Molecular characterization and functional analysis of serine/threonine protein phosphatase of Toxocara canis.

    Science.gov (United States)

    Ma, Guang Xu; Zhou, Rong Qiong; Hu, Shi Jun; Huang, Han Cheng; Zhu, Tao; Xia, Qing You

    2014-06-01

    Toxocara canis (T. canis) is a widely prevalent zoonotic parasite that infects a wide range of mammalian hosts, including humans. We generated the full-length complementary DNA (cDNA) of the serine/threonine phosphatase gene of T. canis (Tc stp) using 5' rapid amplification of the cDNA ends. The 1192-bp sequence contained a continuous 942-nucleotide open reading frame, encoding a 313-amino-acid polypeptide. The Tc STP polypeptide shares a high level of amino-acid sequence identity with the predicted STPs of Loa loa (89%), Brugia malayi (86%), Oesophagostomum columbianum (76%), and Oesophagostomumdentatum (76%). The Tc STP contains GDXHG, GDXVDRG, GNHE motifs, which are characteristic of members of the phosphoprotein phosphatase family. Our quantitative real-time polymerase chain reaction analysis showed that the Tc STP was expressed in six different tissues in the adult male, with high-level expression in the spermary, vas deferens, and musculature, but was not expressed in the adult female, suggesting that Tc STP might be involved in spermatogenesis and mating behavior. Thus, STP might represent a potential molecular target for controlling T. canis reproduction. Copyright © 2014 Elsevier Inc. All rights reserved.

  14. sero-epidemiology of toxocara canis infection in chil- dren attending ...

    African Journals Online (AJOL)

    2015-06-01

    Jun 1, 2015 ... dogs.2. The prevalence of toxocariasis is generally higher in tropical and developing countries than in developed countries and has been associated with .... canis sero-positivity and characteris- tics of children attending four selected hospitals in the. Central Region, Ghana. Variable Group. (Characteristic).

  15. Abnormal neurobehaviour and impaired memory function as a consequence of Toxocara canis- as well as Toxocara cati-induced neurotoxocarosis.

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    Elisabeth Janecek

    2017-05-01

    Full Text Available Neuroinvasive larvae of the worldwide occurring zoonotic roundworms Toxocara canis and T. cati may induce neurotoxocarosis (NT in humans, provoking a variety of symptoms including cognitive deficits as well as neurological dysfunctions. An association with neuropsychological disorders has been discussed. Similar symptoms have been described in T. canis-infected mice, whereas data on T. cati-induced NT are rare. Therefore, it was aimed to obtain insights into the impact on neurobehaviour as well as progression of neurological symptoms and behavioural alterations during the course of NT directly comparing T. canis- and T. cati-infected mice as models for human NT.C57BL/6 mice were orally infected with 2000 embryonated T. canis or T. cati eggs, respectively, the control group received tap water. Mice were screened weekly for neurobehavioural alterations and memory function starting one day prior infection until 97 days post infection (pi; T. canis-infection and day 118 pi (T. cati-infection, uninfected control. Mostly motoric and neurological parameters were affected in T. canis-infected mice starting day 20 pi with severe progression accompanied by stereotypical circling. In contrast, T. cati-infected mice mostly showed reduced response to sudden sound stimulus (indicator for excitability and flight behaviour starting day 6 pi. Interestingly, enhanced grooming behaviour was observed exclusively in T. cati-infected mice, indicating a possible role of neurotransmitter dysregulation. Reduced exploratory behaviour and memory impairment was observed in both infection groups with delayed onset and less severe progression in T. cati- compared to T. canis-infected mice.Results highlight the need to consider T. cati beside T. canis as causative agent of human NT. Findings provide valuable hints towards differences in key regulatory mechanisms during T. canis- and T. cati-induced NT, contributing to a comprehensive picture and consequently a broader

  16. Molecular Detection and Prevalence of Hepatozoon canis in Dogs from Punjab (Pakistan) and Hematological Profile of Infected Dogs.

    Science.gov (United States)

    Qamar, Muhammad; Malik, Muhammad Irfan; Latif, Muhammad; Ain, Qurat Ul; Aktas, Munir; Shaikh, Rehan Sadiq; Iqbal, Furhan

    2017-03-01

    The intraleukocytic parasite, Hepatozoon canis, causes the sometimes fatal tick borne disease canine hepatozoonosis. In this study, dogs from Islamabad, Lahore, and Multan Districts of the Punjab region of Pakistan were surveyed to investigate the presence and prevalence of H. canis infection and to determine the effects of the parasite on hematological parameters. Blood samples were collected from 151 domestic dogs (149 pet, 2 stray) of both sexes and varying ages. Data on sex, age, tick infestation, and clinical factors (body temperature, mucous membrane status, and presence of hematuria and vomiting) were collected. Using PCR, 18 dogs (11.9%) were found positive for the presence of H. canis DNA. Partial sequences of the 18S rRNA gene shared 99-100% similarity with the corresponding H. canis isolates. This epidemiological survey revealed higher prevalence of H. canis in Islamabad (11/49, 22.4%) compared to Lahore (3/52, 5.8%) and Multan (4/50, 8%) in Pakistan. No investigated epidemiological or clinical factors were found to be associated with the presence of H. canis (p > 0.05) in dogs. H. canis positive dogs exhibited higher minimum inhibitory dilution (p = 0.04), mixed inclusion (p = 0.008) and relative distribution width of red blood cells (p = 0.02), and lower hematocrit (p = 0.03) and mean hemoglobin content (p = 0.03) than did dogs in which H. canis was not detected. We are recommending this PCR-based protocol to the veterinary practitioners for the detection and/or confirmation of H. canis in dogs suspected for hepatozoonosis to improve their health status.

  17. Behavioural ecology cannot turn its back on Lévy walk research. Comment on "Liberating Lévy walk research from the shackles of optimal foraging" by A.M. Reynolds

    Science.gov (United States)

    Bartumeus, Frederic

    2015-09-01

    Interdisciplinary research on Lévy walks at the intersection between physics and biology is here to stay, albeit the scope of its role and utility in different areas of biology, including animal foraging, are still to be defined. After a decade, the field is still sorting out relevant questions from misleading interpretations, separating the wheat from the chaff. This task should be easy but it is not. Some reasons are the interdisciplinarity of the subject (maths, physics, biology), which multiplies semantic problems and the questions of interest, and the tight combination of theory and data that is needed to advance in the field.

  18. Occurrence of Hepatozoon canis (Adeleorina: Hepatozoidae) and Anaplasma spp. (Rickettsiales: Anaplasmataceae) in black-backed jackals (Canis mesomelas) in South Africa.

    Science.gov (United States)

    Penzhorn, Barend L; Netherlands, Edward C; Cook, Courtney A; Smit, Nico J; Vorster, Ilse; Harrison-White, Robert F; Oosthuizen, Marinda C

    2018-03-20

    Domestic dogs are not native to sub-Saharan Africa, which may account for their susceptibility to Babesia rossi, of which endemic black-backed jackals (Canis mesomelas) are natural reservoirs. There is virtually no information on the occurrence of potentially pathogenic haemogregarines (e.g. Hepatozoon canis) or even rickettsial bacteria (e.g. Ehrlichia spp. and Anaplasma spp.) in indigenous canids in sub-Saharan Africa. Such organisms could pose a risk to domestic dogs, as well as to populations of endangered indigenous canid species. Genomic DNA extracted from blood samples taken from 126 free-ranging and 16 captive black-backed jackals was subjected to reverse line blot (RLB) hybridization assay; 82 (57.8%) specimens reacted only with the Ehrlichia/Anaplasma genera-specific probe. Full-length bacterial 16S rRNA gene of five of these specimens was cloned and the recombinants sequenced. The ten 16S rDNA sequences obtained were most closely related, with approximately 99% identity, to Anaplasma sp. South African Dog, various uncultured Anaplasma spp., as well as various Anaplasma phagocytophilum genotypes. Ninety-one specimens were screened for haemogregarines through PCR amplification using the 18S rRNA gene; 20 (21.9%) specimens reacted positively, of which 14 (15.4%) were confirmed positive for Hepatozoon genotypes from within H. canis. Two (2.2%) specimens were found positive for two different Hepatozoon genotypes. Sequence analyses confirmed the presence of 16S rDNA sequences closely related to A. phagocytophilum and Anaplasma sp. South African Dog as well as two H. canis genotypes in both free-ranging and captive black-backed jackals. Distinguishing between closely related lineages may provide insight into differences in pathogenicity and virulence of various Anaplasma and H. canis genotypes. By building up a more comprehensive understanding of the range and diversity of the bacteria and eukaryotic organisms (piroplasms and haemogregarines) in the blood of

  19. Endocarditis por Brucella canis: primer caso documentado en un paciente adulto en Argentina Brucella canis endocarditis: first documented case in Argentina

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    Valeria Manias

    2013-03-01

    Full Text Available Se describe el primer caso documentado de endocarditis por Brucella canis en Argentina. El paciente fue un varón adulto que consultó por edemas en miembros inferiores, registros febriles aislados de 2 meses de evolución y dolor precordial opresivo que irradiaba a brazo izquierdo. Negaba contacto con animales de cría o consumo de productos sin pasteurización. Estudios cardiológicos constataron endocarditis infecciosa. Se resuelve cirugía de recambio valvular ante fracaso terapéutico empírico con cefalotina, ampicilina y gentamicina. Los hemocultivos fueron positivos (4 de 4 muestras con bacilos gram negativos. Se realizó la identificación con técnica API 20 NE (bioMérieux, el método automatizado Phoenix (BD y las pruebas bioquímicas convencionales, sin concluir género ni especie. Se derivó la cepa al departamento de Bacteriología Especial INEI-ANLIS "Dr. Carlos G. Malbrán" donde se identificó al aislamiento como Brucella canis. Se rotó el esquema terapéutico a doxiciclina, rifampicina y trimetoprima-sulfametoxazol con buena evolución. La importancia del caso radica en la posible falla del tratamiento antimicrobiano empírico administrado para endocarditis, ya que B. canis no responde a los antimicrobianos convencionales para esta patología.We herein present the case of an adult male patient who consulted for lower extremity edema, a 2- month history of fever and oppressive chest pain radiating to the left arm. He referred neither contact with breeding animals nor consumption of unpasteurized dairy products. A diagnosis of endocarditis was confirmed by cardiac studies. Since the empirical treatment with cephalotin, ampicillin and gentamicin failed, the patient underwent aortic valve replacement. A total of four blood cultures were positive with a gram-negative rod. Bacterial identification was performed using the API 20 NE technique (bioMerieux, the Phoenix automated method (BD and conventional biochemical tests which were

  20. Prevalence and diversity of Hepatozoon canis in naturally infected dogs in Japanese islands and peninsulas.

    Science.gov (United States)

    El-Dakhly, Khaled Mohamed; Goto, Minami; Noishiki, Kaori; El-Nahass, El-Shaymaa; Hirata, Akihiro; Sakai, Hiroki; Takashima, Yasuhiro; El-Morsey, Ahmed; Yanai, Tokuma

    2013-09-01

    Canine hepatozoonosis is a worldwide protozoal disease caused by Hepatozoon canis and Hepatozoon americanum and is transmitted by ixodid ticks, Rhipicephalus and Amblyomma spp., respectively. H. canis infection is widespread in Africa, Europe, South America, and Asia, including Japan. The objective of this study was to study the distribution pattern and diversity of H. canis in naturally infected dogs in nine Japanese islands and peninsulas. Therefore, 196 hunting dogs were randomly sampled during the period from March to September 2011 and the ages and sexes were identified. Direct microscopy using Giemsa-stained blood smears revealed H. canis gametocytes in the peripheral blood of 45 (23.6%) dogs. Polymerase chain reaction (PCR) was performed on EDTA-anticoagulated blood, initially with the common primer set (B18S-F and B18S-R) amplifying the 1,665-bp portion of the 18S rRNA gene, and then with the specific primer set (HepF and HepR) amplifying about 660 bp fragments of the same gene. Based on PCR, 84 (42.9%) dogs were positive using the common primer and 81 (41.3%) were positive using the specific primer. The current investigation indicated that all screened areas, except for Sado Island and Atsumi Peninsula, were infected. Yaku Island had the highest infection rate (84.6% in males and 100.0% in females), while Ishigaki Island showed the lowest infection rates (8.3% in males and 17.7% in females). Both sexes were infected with no significant difference. However, diversity of infection among the surveyed islands and peninsulas was significantly different (P canis has previously been reported in dogs in Japan, the higher infection rate described in the current study and the diversity of infection in a wide range of islands strongly encourage prospective studies dealing with the prevention and treatment of the infection in dogs, as well as control of ticks.

  1. Genome characterization and population genetic structure of the zoonotic pathogen, Streptococcus canis

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    Richards Vincent P

    2012-12-01

    Full Text Available Abstract Background Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Results Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection. A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs [plasmid, phage, integrative conjugative element (ICE] and comparison to other species provided convincing evidence for lateral gene transfer (LGT between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae, with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST of a subset of the isolates (n = 45 detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types], suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. Conclusion This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human

  2. Genome characterization and population genetic structure of the zoonotic pathogen, Streptococcus canis.

    Science.gov (United States)

    Richards, Vincent P; Zadoks, Ruth N; Pavinski Bitar, Paulina D; Lefébure, Tristan; Lang, Ping; Werner, Brenda; Tikofsky, Linda; Moroni, Paolo; Stanhope, Michael J

    2012-12-18

    Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus urinalis) is cause for concern

  3. Clinical Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum infections in dogs.

    Science.gov (United States)

    Dubey, J P; Chapman, Jennifer L; Rosenthal, Benjamin M; Mense, M; Schueler, Ronald L

    2006-04-15

    Sarcocystis neurona, Sarcocystis canis, Toxoplasma gondii, and Neospora caninum are related apicomplexans that can cause systemic illness in many species of animals, including dogs. We investigated one breeder's 25 Basset Hounds for these infections. In addition, tissues from dogs and other non-canine hosts previously reported as S. canis infections were studied retrospectively. Schizonts resembling those of S. neurona, and recognized by polyclonal rabbit anti-S. neurona antibodies, were found in six of eight retrospective cases, as well as in two additional dogs (one Basset Hound, one Springer Spaniel) not previously reported. S. neurona schizonts were found in several tissues including the central nervous system, lungs, and kidneys. Fatal toxoplasmosis was diagnosed in an adult dog, and neosporosis was diagnosed in an adult and a pup related to the one diagnosed with S. neurona. No serological reactivity to S. neurona antibodies occurred when S. canis-like liver schizonts were retrospectively assayed from two dogs, a dolphin, a sea lion, a horse, a chinchilla, a black or either of two polar bears. Sequencing conserved (18S) and variable (ITS-1) portions of nuclear ribosomal DNA isolated from the schizont-laden liver of a polar bear distinguished it from all previously characterized species of Sarcocystis. We take this genetic signature as provisionally representative of S. canis, an assumption that should be tested with future sequencing of similar liver infections in other mammalian hosts. These findings further extend the uncharacteristically broad intermediate host range for S. neurona, which also causes a neurologic disease in cats, mink, raccoons, skunks, Pacific harbor seals, ponies, zebras, lynxes, and sea otters. Further work is necessary to delineate the causative agent(s) of other cases of canine sarcocystosis, and in particular to specify the attributes of S. canis, which corresponds morphologically to infections reported from wide range of terrestrial

  4. Serological survey of Brucella canis in dogs in urban Harare and selected rural communities in Zimbabwe

    Directory of Open Access Journals (Sweden)

    Simbarashe Chinyoka

    2014-04-01

    Full Text Available A cross-sectional study was conducted in order to detect antibodies for Brucella canis (B. canis in dogs from urban Harare and five selected rural communities in Zimbabwe. Sera from randomly selected dogs were tested for antibodies to B. canis using an enzyme-linked immunosorbent assay. Overall, 17.6% of sera samples tested (57/324, 95% CI: 13.5–21.7 were positive for B. canis antibodies. For rural dogs, seroprevalence varied from 11.7% – 37.9%. Rural dogs recorded a higher seroprevalence (20.7%, 95% CI: 15.0–26.4 compared with Harare urban dogs (12.7%, 95% CI: 6.9–18.5 but the difference was not significant (p = 0.07. Female dogs from both sectors had a higher seroprevalence compared with males, but the differences were not significant (p > 0.05. Five and two of the positive rural dogs had titres of 1:800 and 1:1600, respectively, whilst none of the positive urban dogs had a titre above 1:400. This study showed that brucellosis was present and could be considered a risk to dogs from the studied areas. Further studies are recommended in order to give insight into the epidemiology of brucellosis in dogs and its possible zoonotic consequences in Zimbabwe. Screening for other Brucella spp. (Brucella abortus, Brucella melitensis and Brucella suis other than B. canis is also recommended.

  5. Genome characterization and population genetic structure of the zoonotic pathogen, Streptococcus canis

    Science.gov (United States)

    2012-01-01

    Background Streptococcus canis is an important opportunistic pathogen of dogs and cats that can also infect a wide range of additional mammals including cows where it can cause mastitis. It is also an emerging human pathogen. Results Here we provide characterization of the first genome sequence for this species, strain FSL S3-227 (milk isolate from a cow with an intra-mammary infection). A diverse array of putative virulence factors was encoded by the S. canis FSL S3-227 genome. Approximately 75% of these gene sequences were homologous to known Streptococcal virulence factors involved in invasion, evasion, and colonization. Present in the genome are multiple potentially mobile genetic elements (MGEs) [plasmid, phage, integrative conjugative element (ICE)] and comparison to other species provided convincing evidence for lateral gene transfer (LGT) between S. canis and two additional bovine mastitis causing pathogens (Streptococcus agalactiae, and Streptococcus dysgalactiae subsp. dysgalactiae), with this transfer possibly contributing to host adaptation. Population structure among isolates obtained from Europe and USA [bovine = 56, canine = 26, and feline = 1] was explored. Ribotyping of all isolates and multi locus sequence typing (MLST) of a subset of the isolates (n = 45) detected significant differentiation between bovine and canine isolates (Fisher exact test: P = 0.0000 [ribotypes], P = 0.0030 [sequence types]), suggesting possible host adaptation of some genotypes. Concurrently, the ancestral clonal complex (54% of isolates) occurred in many tissue types, all hosts, and all geographic locations suggesting the possibility of a wide and diverse niche. Conclusion This study provides evidence highlighting the importance of LGT in the evolution of the bacteria S. canis, specifically, its possible role in host adaptation and acquisition of virulence factors. Furthermore, recent LGT detected between S. canis and human bacteria (Streptococcus

  6. A search for photometric and spectroscopic evolutionary changes in the young planetary nebula Vy 2-2

    Science.gov (United States)

    Arkhipova, V. P.; Burlak, M. A.; Esipov, V. F.; Ikonnikova, N. P.; Komissarova, G. V.

    2017-12-01

    The results of long-term photometric and spectroscopic observations of the young compact planetary nebula Vy 2-2 (PNG 045.4-02.7) are presented. The UBV photometry in 1990-2016 has revealed a slight brightness trend in the yearly averaged data, most pronounced in the V band. We have measured the relative fluxes of optical emission lines on the spectrograms taken with the 1.25-m telescope at the Southern Station of the SAI MSU in 1999-2016, estimated the absolute flux in the Hβ line to be F(H β) = (2.1 ± 0.4) × 10-12 erg cm-2 s-1, and determined the interstellar extinction constant c(Hβ) = 1.8. The electron temperature and density in the nebula have been estimated from diagnostic line ratios: Te = (10-12) × 103 K and Ne ≥ 105 cm-3. To detect any possible evolutionary changes, we have compared the new observations with the archival data obtained over the entire history of spectroscopic observations of Vy 2-2. No significant changes in the relative intensities of the strongest emission lines and the integrated flux in the H β line exceeding the observational errors have been found. We have revealed a tendency for the intensity ratio F(λ4363)/F(λ4959) to decrease with time, which may be related to a decrease in the electron density in the nebula. Based on our photometric and spectroscopic data, we have estimated the luminosity of the central star of Vy 2-2, which corresponds to the evolutionary tracks for the most massive post-AGB stars of the O-rich sequence.

  7. [APPLICATION OF V-Y ADVANCED SENSE-REMAINED POSTERIOR TIBIAL ARTERY PERFORATOR FLAP IN REPAIRING WOUND AROUND ANKLE].

    Science.gov (United States)

    Tang, Xiujun; Wang, Bo; Wei, Zairong; Wang, Dali; Han, Wenjie; Zhang, Wenduo; Li, Shujun

    2015-12-01

    OBJECTIVE To explore the feasibility and effectiveness of V-Y advanced sense-remained posterior tibial artery perforator flap in repairing wound around the ankle. METHODS Between March 2012 and January 2015, 11 patients with wounds around the ankle were treated by V-Y advanced sense-remained posterior tibial artery perforator flap. There were 6 males and 5 females with a median age of 37 years (range, 21-56 years). The causes were traffic accident injury in 3 cases, thermal injury in 2 cases, burn in 2 cases, iatrogenic wounds in 2 cases, and local contusion in 2 cases. The disease duration ranged from 1 to 3 weeks (mean, 2 weeks). Injury was located at the medial malleolus in 4 cases, at the lateral malleolus in 3 cases, and at the heel in 4 cases. All had exposure of bone, tendon, or plate. The defect area ranged from 4 cmx2 cm to 5 cmx3 cm; the area of the flap ranged from 11 cmx4 cm to 15 cmx6 cm. Necrosis of distal flap occurred in 1 case after operation; re-operation to amputate the posterior tibial artery was given and the wound was repaired by proximal skin graft. Light necrosis of distal end was observed in 2 cases, and wound healed at 3 weeks after dressing. And other flaps successfully survived, and primary healing of wounds were obtained. The patients were followed up 6-24 months (mean, 11 months). The flaps were good in color, texture, and appearance. The ankle joint had normal activity. At last follow-up, 10 cases restored fine sense, and 1 case restored protective feeling with posterior tibial artery advanced flap after amputation. V-Y advanced sense-remained posterior tibial artery perforator flap has the advantages of reliable blood supply, simple operation, good appearance, and sensory recovery. Therefore, it is an ideal method to repair wound around the ankle.

  8. vy-taxis: a novel search strategy for finding odor plumes in turbulent flow-dominated environments

    Science.gov (United States)

    Pasternak, Zohar; Bartumeus, Frederic; Grasso, Frank W.

    2009-10-01

    Locating chemical plumes in aquatic or terrestrial environments is important for many economic, conservation, security and health related human activities. The localization process is composed mainly of two phases: finding the chemical plume and then tracking it to its source. Plume tracking has been the subject of considerable study whereas plume finding has received little attention. We address here the latter issue, where the searching agent must find the plume in a region often many times larger than the plume and devoid of the relevant chemical cues. The probability of detecting the plume not only depends on the movements of the searching agent but also on the fluid mechanical regime, shaping plume intermittency in space and time; this is a basic, general problem when exploring for ephemeral resources (e.g. moving and/or concealing targets). Here we present a bio-inspired search strategy named Lévy-taxis that, under certain conditions, located odor plumes significantly faster and with a better success rate than other search strategies such as Lévy walks (LW), correlated random walks (CRW) and systematic zig-zag. These results are based on computer simulations which contain, for the first time ever, digitalized real-world water flow and chemical plume instead of their theoretical model approximations. Combining elements of LW and CRW, Lévy-taxis is particularly efficient for searching in flow-dominated environments: it adaptively controls the stochastic search pattern using environmental information (i.e. flow) that is available throughout the course of the search and shows correlation with the source providing the cues. This strategy finds natural application in real-world search missions, both by humans and autonomous robots, since it accomodates the stochastic nature of chemical mixing in turbulent flows. In addition, it may prove useful in the field of behavioral ecology, explaining and predicting the movement patterns of various animals searching for

  9. Permanence and asymptotic behaviors of stochastic predator-prey system with Markovian switching and Lévy noise

    Science.gov (United States)

    Wang, Sheng; Wang, Linshan; Wei, Tengda

    2018-04-01

    This paper concerns the dynamics of a stochastic predator-prey system with Markovian switching and Lévy noise. First, the existence and uniqueness of global positive solution to the system is proved. Then, by combining stochastic analytical techniques with M-matrix analysis, sufficient conditions of stochastic permanence and extinction are obtained. Furthermore, for the stochastic permanence case, by means of four constants related to the stationary probability distribution of the Markov chain and the parameters of the subsystems, both the superior limit and the inferior limit of the average in time of the sample path of the solution are estimated. Finally, our conclusions are illustrated through an example.

  10. Exponential synchronization of delayed neutral-type neural networks with Lévy noise under non-Lipschitz condition

    Science.gov (United States)

    Ma, Shuo; Kang, Yanmei

    2018-04-01

    In this paper, the exponential synchronization of stochastic neutral-type neural networks with time-varying delay and Lévy noise under non-Lipschitz condition is investigated for the first time. Using the general Itô's formula and the nonnegative semi-martingale convergence theorem, we derive general sufficient conditions of two kinds of exponential synchronization for the drive system and the response system with adaptive control. Numerical examples are presented to verify the effectiveness of the proposed criteria.

  11. Schrödinger problem, Lévy processes, and noise in relativistic quantum mechanics

    Science.gov (United States)

    Garbaczewski, Piotr; Klauder, John R.; Olkiewicz, Robert

    1995-05-01

    The main purpose of the paper is an essentially probabilistic analysis of relativistic quantum mechanics. It is based on the assumption that whenever probability distributions arise, there exists a stochastic process that is either responsible for the temporal evolution of a given measure or preserves the measure in the stationary case. Our departure point is the so-called Schrödinger problem of probabilistic evolution, which provides for a unique Markov stochastic interpolation between any given pair of boundary probability densities for a process covering a fixed, finite duration of time, provided we have decided a priori what kind of primordial dynamical semigroup transition mechanism is involved. In the nonrelativistic theory, including quantum mechanics, Feynman-Kac-like kernels are the building blocks for suitable transition probability densities of the process. In the standard ``free'' case (Feynman-Kac potential equal to zero) the familiar Wiener noise is recovered. In the framework of the Schrödinger problem, the ``free noise'' can also be extended to any infinitely divisible probability law, as covered by the Lévy-Khintchine formula. Since the relativistic Hamiltonians ||∇|| and √-Δ+m2 -m are known to generate such laws, we focus on them for the analysis of probabilistic phenomena, which are shown to be associated with the relativistic wave (D'Alembert) and matter-wave (Klein-Gordon) equations, respectively. We show that such stochastic processes exist and are spatial jump processes. In general, in the presence of external potentials, they do not share the Markov property, except for stationary situations. A concrete example of the pseudodifferential Cauchy-Schrödinger evolution is analyzed in detail. The relativistic covariance of related wave equations is exploited to demonstrate how the associated stochastic jump processes comply with the principles of special relativity.

  12. Diphyllobothrium pacificum (Nybelin, 1931) Margolis, 1956 en Canis familiaris de la ciudad de Chincha, Perú

    OpenAIRE

    Cabrera, Ch; Tantaleán V, Manuel; Rojas M, Ricardo

    2001-01-01

    In this communication is presented the finding of the tapeworm Diphyllobothrium pacificum, parasite of sea lions, in Canis familiaris (dog) in Chincha city, Peru. This is the first canine infection with D. pacificum in the South Peruvian coast

  13. Detection of Babesia canis vogeli and Hepatozoon canis in canine blood by a single-tube real-time fluorescence resonance energy transfer polymerase chain reaction assay and melting curve analysis.

    Science.gov (United States)

    Kongklieng, Amornmas; Intapan, Pewpan M; Boonmars, Thidarut; Thanchomnang, Tongjit; Janwan, Penchom; Sanpool, Oranuch; Lulitanond, Viraphong; Taweethavonsawat, Piyanan; Chungpivat, Sudchit; Maleewong, Wanchai

    2015-03-01

    A real-time fluorescence resonance energy transfer polymerase chain reaction (qFRET PCR) coupled with melting curve analysis was developed for detection of Babesia canis vogeli and Hepatozoon canis infections in canine blood samples in a single tube assay. The target of the assay was a region within the 18S ribosomal RNA gene amplified in either species by a single pair of primers. Following amplification from the DNA of infected dog blood, a fluorescence melting curve analysis was done. The 2 species, B. canis vogeli and H. canis, could be detected and differentiated in infected dog blood samples (n = 37) with high sensitivity (100%). The detection limit for B. canis vogeli was 15 copies of a positive control plasmid, and for H. canis, it was 150 copies of a positive control plasmid. The assay could simultaneously distinguish the DNA of both parasites from the DNA of controls. Blood samples from 5 noninfected dogs were negative, indicating high specificity. Several samples can be run at the same time. The assay can reduce misdiagnosis and the time associated with microscopic examination, and is not prone to the carryover contamination associated with the agarose gel electrophoresis step of conventional PCR. In addition, this qFRET PCR method would be useful to accurately determine the range of endemic areas or to discover those areas where the 2 parasites co-circulate. © 2015 The Author(s).

  14. Questing Dermacentor reticulatus harbouring Babesia canis DNA associated with outbreaks of canine babesiosis in the Swiss Midlands.

    Science.gov (United States)

    Schaarschmidt, Daniel; Gilli, Urs; Gottstein, Bruno; Marreros, Nelson; Kuhnert, Peter; Daeppen, Jérôme A; Rosenberg, Gertrud; Hirt, Didier; Frey, Caroline F

    2013-06-01

    In 2011 and 2012, outbreaks of clinical canine babesiosis were observed in 2 areas of the Swiss Midlands that had no history of this disease so far. In one area, cases of canine babesiosis occurred over 2 consecutive tick seasons. The outbreaks involved 29 dogs, 4 of which died. All dogs were infected with large Babesia sp. as diagnosed in Giemsa-stained blood smears and/or PCR. These were identified as B. canis (formerly known as B. canis canis) by subsequent partial sequencing of the 18S rRNA gene of Babesia sp. Interestingly, the sequence indicated either a genotype with heterogeneity in the ssrRNA gene copies or double infection with different B. canis isolates. None of the dogs had a recent travel history, but one had frequently travelled to Hungary and had suffered twice from clinical babesiosis 18 and 24 months prior to the outbreak in autumn 2011. Retrospective sequencing of a stored blood DNA sample of this dog revealed B. canis, with an identical sequence to the Babesia involved in the outbreaks. For the first time in Switzerland, the partial 18S rRNA gene of B. canis could be amplified from DNA isolated from 19 out of 23 adult Dermacentor reticulatus ticks flagged in the same area. The sequence was identical to that found in the dogs. Furthermore, one affected dog carried a female D. reticulatus tick harbouring B. canis DNA. Our findings illustrate that, under favourable biogeographic and climatic conditions, the life-cycle of B. canis can relatively rapidly establish itself in previously non-endemic areas. Canine babesiosis should therefore always be a differential diagnosis when dogs with typical clinical signs are presented, regardless of known endemic areas. Copyright © 2013 Elsevier GmbH. All rights reserved.

  15. Pricing derivatives under Lévy models modern finite-difference and pseudo-differential operators approach

    CERN Document Server

    Itkin, Andrey

    2017-01-01

    This monograph presents a novel numerical approach to solving partial integro-differential equations arising in asset pricing models with jumps, which greatly exceeds the efficiency of existing approaches. The method, based on pseudo-differential operators and several original contributions to the theory of finite-difference schemes, is new as applied to the Lévy processes in finance, and is herein presented for the first time in a single volume. The results within, developed in a series of research papers, are collected and arranged together with the necessary background material from Lévy processes, the modern theory of finite-difference schemes, the theory of M-matrices and EM-matrices, etc., thus forming a self-contained work that gives the reader a smooth introduction to the subject. For readers with no knowledge of finance, a short explanation of the main financial terms and notions used in the book is given in the glossary. The latter part of the book demonstrates the efficacy of the method by solvin...

  16. The Lévy flight foraging hypothesis: forgetting about memory may lead to false verification of Brownian motion.

    Science.gov (United States)

    Gautestad, Arild O; Mysterud, Atle

    2013-01-01

    The Lévy flight foraging hypothesis predicts a transition from scale-free Lévy walk (LW) to scale-specific Brownian motion (BM) as an animal moves from resource-poor towards resource-rich environment. However, the LW-BM continuum implies a premise of memory-less search, which contradicts the cognitive capacity of vertebrates. We describe methods to test if apparent support for LW-BM transitions may rather be a statistical artifact from movement under varying intensity of site fidelity. A higher frequency of returns to previously visited patches (stronger site fidelity) may erroneously be interpreted as a switch from LW towards BM. Simulations of scale-free, memory-enhanced space use illustrate how the ratio between return events and scale-free exploratory movement translates to varying strength of site fidelity. An expanded analysis of GPS data of 18 female red deer, Cervus elaphus, strengthens previous empirical support of memory-enhanced and scale-free space use in a northern forest ecosystem. A statistical mechanical model architecture that describes foraging under environment-dependent variation of site fidelity may allow for higher realism of optimal search models and movement ecology in general, in particular for vertebrates with high cognitive capacity.

  17. Gross domestic product growth rates as confined Lévy flights: Towards a unifying theory of economic growth rate fluctuations

    Science.gov (United States)

    Lera, Sandro Claudio; Sornette, Didier

    2018-01-01

    A model that combines economic growth rate fluctuations at the microscopic and macroscopic levels is presented. At the microscopic level, firms are growing at different rates while also being exposed to idiosyncratic shocks at the firm and sector levels. We describe such fluctuations as independent Lévy-stable fluctuations, varying over multiple orders of magnitude. These fluctuations are aggregated and measured at the macroscopic level in averaged economic output quantities such as GDP. A fundamental question is thereby to what extent individual firm size fluctuations can have a noticeable impact on the overall economy. We argue that this question can be answered by considering the Lévy fluctuations as embedded in a steep confining potential well, ensuring nonlinear mean-reversal behavior, without having to rely on microscopic details of the system. The steepness of the potential well directly controls the extent to which idiosyncratic shocks to firms and sectors are damped at the level of the economy. Additionally, the theory naturally accounts for business cycles, represented in terms of a bimodal economic output distribution and thus connects two so far unrelated fields in economics. By analyzing 200 years of U.S. gross domestic product growth rates, we find that the model is in good agreement with the data.

  18. Computable error estimates of a finite difference scheme for option pricing in exponential Lévy models

    KAUST Repository

    Kiessling, Jonas

    2014-05-06

    Option prices in exponential Lévy models solve certain partial integro-differential equations. This work focuses on developing novel, computable error approximations for a finite difference scheme that is suitable for solving such PIDEs. The scheme was introduced in (Cont and Voltchkova, SIAM J. Numer. Anal. 43(4):1596-1626, 2005). The main results of this work are new estimates of the dominating error terms, namely the time and space discretisation errors. In addition, the leading order terms of the error estimates are determined in a form that is more amenable to computations. The payoff is only assumed to satisfy an exponential growth condition, it is not assumed to be Lipschitz continuous as in previous works. If the underlying Lévy process has infinite jump activity, then the jumps smaller than some (Formula presented.) are approximated by diffusion. The resulting diffusion approximation error is also estimated, with leading order term in computable form, as well as the dependence of the time and space discretisation errors on this approximation. Consequently, it is possible to determine how to jointly choose the space and time grid sizes and the cut off parameter (Formula presented.). © 2014 Springer Science+Business Media Dordrecht.

  19. Occurrence of Hepatozoon canis and Cercopithifilaria bainae in an off-host population of Rhipicephalus sanguineus sensu lato ticks.

    Science.gov (United States)

    Ramos, Rafael Antonio Nascimento; Giannelli, Alessio; Carbone, Domenico; Baneth, Gad; Dantas-Torres, Filipe; Otranto, Domenico

    2014-04-01

    Hepatozoon canis (Eucoccidiorida, Hepatozoidae) and the filarioid Cercopithifilaria bainae (Spirurida, Onchocercidae) are tick-transmitted infectious agents of dogs, highly prevalent in the Mediterranean basin in association with Rhipicephalus sanguineus sensu lato. Ticks were collected from the environment every 25±2 days in a confined location in southern Italy where a community of dogs lives, from August 2012 to July 2013. In order to study the occurrence of H. canis and C. bainae, 1091 tick specimens (770 adults; 271 nymphs, and 50 larvae) were dissected, and oocysts of H. canis and larvae of C. bainae were morphologically identified. Out of 1091 dissected ticks, 13.47% (n=147) were positive for H. canis, with the highest prevalence recorded in unfed adults (16.4%; 126/770), followed by nymphs collected as larvae and allowed to moult (14%; 7/50), unfed nymphs dissected immediately after collection (3%; 8/271), and adults collected as nymphs and allowed to moult (2%; 6/271). The highest number of H. canis-positive ticks (35.5%; 43/121; Pcanis and C. bainae infections in the study area seem to be dependent on the seasonality of vector tick populations. Hence, dogs living in these areas are more exposed to both pathogens during the warmer months. These findings provide new insights into the ecology of both H. canis and C. bainae. Copyright © 2014 Elsevier GmbH. All rights reserved.

  20. Comparison of the effect of the rotation palatoplasty and V-Y pushback palatoplasty techniques on palate elongation with magnetic resonance imaging.

    Science.gov (United States)

    Isik, D; Bora, A; Yuce, S; Davran, R; Kocak, O F; Canbaz, Y; Avcu, S; Atik, B

    2015-06-01

    Most surgical techniques used in cleft palate repair require the extension of the palate to the pharynx. However, no adequate information exists regarding the extent to which this elongation obtained during operation continues in late postoperative period. In this study, we compared and measured palate elongation in patients with a cleft palate who underwent a V-Y pushback or rotation palatoplasty, by means of magnetic resonance images obtained before and 1 year after surgery. The hard palate, soft palate, and total palate lengths were measured for all of the patients, and the velopharyngeal opening area width was calculated. In patients who underwent the V-Y pushback technique (n=13), the total palate and soft palate lengths were shortened by an average of 0.10 and 0.14cm after surgery, respectively. However, the hard palate length was elongated by an average of 0.13cm. In the rotation palatoplasty group (n=13), the total palate, hard palate, and soft palate lengths were elongated by 0.57, 0.10, and 0.49cm, respectively. The velopharyngeal opening was narrowed by 0.06cm(2) using the V-Y pushback technique and by 0.29cm(2) using the rotational palatoplasty. This study demonstrated that the palate does not elongate during the V-Y pushback technique, as expected. However, rotational palatoplasty elongates the soft palate. Copyright © 2015 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.

  1. Comparison of fasciocutaneous V-Y and rotational flaps for defect coverage of sacral pressure sores: a critical single-centre appraisal.

    Science.gov (United States)

    Djedovic, Gabriel; Metzler, Julia; Morandi, Evi M; Wachter, Tanja; Kühn, Shafreena; Pierer, Gerhard; Rieger, Ulrich M

    2017-12-01

    Pressure sore rates remain high in both nursing homes as well as in hospitals. Numerous surgical options are available for defect coverage in the sacral region. However, objective data is scarce as to whether a specific flap design is superior to another. Here, we aim to compare two fasciocutaneous flap designs for sacral defect coverage: the gluteal rotation flap and the gluteal V-Y flap. All primary sacral pressure sores of grades III-IV that were being covered with gluteal fasciocutaneous rotational or V-Y flaps between January 2008 and December 2014 at our institution were analysed. A total of 41 patients received a total of 52 flaps. Of these, 18 patients received 20 gluteal rotational flaps, and 23 patients received 32 V-Y flaps. Both groups were comparable with regards to demographics, comorbidities and complications. Significantly more V-Y flaps were needed to cover smaller defects. Mean length of hospital stay was significantly prolonged when surgical revision had to be carried out. Both flap designs have proven safe and reliable for defect coverage after sacral pressure sores. Gluteal rotational flaps appear to be more useful for larger defects. Both flap designs facilitate their reuse in case of pressure sore recurrence. Complication rates appear to be comparable in both designs and to the current literature. © 2017 Medicalhelplines.com Inc and John Wiley & Sons Ltd.

  2. Molecular detection of Anaplasma platys, Ehrlichia canis, Hepatozoon canis and Rickettsia monacensis in dogs from Maio Island of Cape Verde archipelago.

    Science.gov (United States)

    Lauzi, Stefania; Maia, João P; Epis, Sara; Marcos, Ricardo; Pereira, Cristina; Luzzago, Camilla; Santos, Marta; Puente-Payo, Pablo; Giordano, Alessia; Pajoro, Massimo; Sironi, Giuseppe; Faustino, Augusto

    2016-07-01

    Tick-borne diseases are emerging worldwide and have an important zoonotic relevance. Dogs play an important role in the epidemiology of several zoonotic tick-borne pathogens acting as sentinels and/or reservoirs. This study focused on the molecular identification of tick-borne pathogens in blood samples of 153 autochthonous asymptomatic dogs in Maio Island, Cape Verde archipelago. Eighty-four (54.9%) dogs were positive for one or more pathogens. Fifty-five (35.9%) dogs were infected with Hepatozoon canis, 53 (34.6%) with Anaplasma platys, five (3.3%) with Ehrlichia canis and Rickettsia monacensis, an emerging human pathogen, was also identified in a single dog (0.7%). The former three pathogens cause important canine tick-borne diseases that are transmitted or potentially transmitted by Rhipicephalus sanguineus s.l., the only hard tick identified in Cape Verde. Furthermore, Wolbachia spp. was amplified from the blood of one dog. None of the dogs were positive for Anaplasma phagocytophilum, Borrelia burgdorferi sensu lato, Midichloria mitochondrii, Bartonella spp., Babesia spp. or Theileria spp. Fifty-four (35.3%) animals showed single infections and 30 (19.6%) co-infections, with A. platys and H. canis co-infection being the most frequent (28 dogs, 18.3%). The frequency of E. canis infection was statistically different among age groups (P=0.017), being higher among dogs older than 4 years compared to younger dogs. Infection by A. platys was also statistically different among age groups (P=0.031), being higher in dogs younger than 2 years compared to older dogs. The statistical analyses showed no significant association of PCR positivity with gender or location. The frequency of tick-borne pathogens detected in dogs in Maio Island, including R. monacensis, highlights the need to improve diagnosis and control in order to prevent the risk of transmission of these pathogens among dogs and humans living in or travelling to this touristic island. Copyright © 2016

  3. The prevalence and impact of Babesia canis and Theileria sp. in free-ranging grey wolf (Canis lupus) populations in Croatia.

    Science.gov (United States)

    Beck, Ana; Huber, Doroteja; Polkinghorne, Adam; Kurilj, Andrea Gudan; Benko, Valerija; Mrljak, Vladimir; Reljić, Slaven; Kusak, Josip; Reil, Irena; Beck, Relja

    2017-04-04

    Babesia spp. and Theileria spp. are important emerging causes of disease in dogs. Alongside these domesticated hosts, there is increasing recognition that these piroplasms can also be found in a range of wild animals with isolated reports describing the presence of these pathogen in foxes (Vulpes vulpes) and captive grey wolves (Canis lupus). The prevalence and impact of these infections in free-ranging populations of canids are unknown. To gain a better insight into the epidemiology and pathogenesis of piroplasm infections in free-ranging grey wolves, pathological and molecular investigations into captive and free-ranging grey wolves in Croatia were performed. The carcasses of 107 free-ranging wolves and one captive wolf were the subjects of post-mortem investigations and sampling for molecular studies. A blood sample from one live captured wolf for telemetric tracking was also used for molecular analysis. PCR amplification targeting the 18S RNA gene revealed that 21 of 108 free-ranging wolves and one captive animal were positive for Theileria/Babesia DNA. Subsequent sequencing of a fragment of the 18S RNA gene revealed that 7/22 animals were positive for Babesia canis while the other amplified sequence were found to be identical with corresponding 18S rDNA sequences of Theileria capreoli isolated from wild deer (15/22). Haematological and cytological analysis revealed the presence of signet-ring shaped or pear-shaped piroplasms in several animals with the overall parasite burden in all positive animals assessed to be very low. Pathological investigation of the captive animal revealed fatal septicemia as a likely outcome of hemolytic anaemia. There was little or no evidence of hemolytic disease consistent with babesiosis in other animals. Importantly, the presence of B. canis in free-ranging grey wolves has not been described before but has been reported in a single fox and domestic dogs only. That B. canis infections cause disease in dogs but have little impact

  4. Constraining Phosphorus Chemistry in Carbon- and Oxygen-Rich Circumstellar Envelopes: Observations of PN, HCP, and CP

    Science.gov (United States)

    Milam, S. N.; Halfen, D. T.; Tenenbaum, E. D.; Apponi, A. J.; Woolf, N. J.; Ziurys, L. M.

    2008-09-01

    Millimeter-wave observations of PN, CP, and HCP have been carried out toward circumstellar envelopes of evolved stars using the Arizona Radio Observatory (ARO). HCP and PN have been identified in the carbon-rich source CRL 2688 via observations at 1 mm using the Submillimeter Telescope (SMT) and 2-3 mm with the Kitt Peak 12 m. An identical set of measurements were carried out toward IRC +10216, as well as observations of CP at 1 mm. PN was also observed toward VY Canis Majoris (VY CMa), an oxygen-rich supergiant star. The PN and HCP line profiles in CRL 2688 and IRC +10216 are roughly flat topped, indicating unresolved, optically thin emission; CP, in contrast, has a distinct "U" shape in IRC +10216. Modeling of the line profiles suggests abundances, relative to H2, of f(PN) ~ (3-5) × 10-9 and f(HCP) ~ 2 × 10-7 in CRL 2688, about an order of magnitude higher than in IRC +10216. In VY CMa, f(PN) is ~4 × 10-8. The data in CRL 2688 and IRC +10216 are consistent with LTE formation of HCP and PN in the inner envelope, as predicted by theoretical calculations, with CP a photodissociation product at larger radii. The observed abundance of PN in VY CMa is a factor of 100 higher than LTE predictions. In IRC +10216, the chemistry of HCP/CP mimics that of HCN/CN and suggests an N2 abundance of f ~ 1 × 10-7. The chemistry of phosphorus appears active in both carbon- and oxygen-rich envelopes of evolved stars.

  5. Duplex quantitative real-time PCR assay for the detection and discrimination of the eggs of Toxocara canis and Toxocara cati (Nematoda, Ascaridoidea) in soil and fecal samples

    OpenAIRE

    Durant, Jean-Francois; Irenge, Leonid M; Fogt-Wyrwas, Renata; Dumont, Catherine; Doucet, Jean-Pierre; Mignon, Bernard; Losson, Bertrand; Gala, Jean-Luc

    2012-01-01

    Abstract Background Toxocarosis is a zoonotic disease caused by Toxocara canis (T. canis) and/or Toxocara cati (T. cati), two worldwide distributed roundworms which are parasites of canids and felids, respectively. Infections of humans occur through ingestion of embryonated eggs of T. canis or T. cati, when playing with soils contaminated with dogs or cats feces. Accordingly, the assessment of potential contamination of these areas with these roundworms eggs is paramount. Methods A duplex qua...

  6. Skin impression with acetate tape in Demodex canis and Scarcoptes scabiei var. vulpes diagnosis

    Directory of Open Access Journals (Sweden)

    D.T. Pereira

    2015-02-01

    Full Text Available This study compares the efficacy of skin impression with acetate tape and the deep skin scraping test to find D. canis and S. scabiei in dogs. During six months, 134 samples were collected by both techniques from 115 dogs treated at the dermatology service of the Veterinary Hospital of the Federal University of Santa Maria (HVU-UFSM. Of these patients, 27 had demodicosis and 12 had scabies. The impression with acetate tape test (ITT was shown to be significantly superior to the deep skin scraping test (DSST in finding D. canis and S. scabiei mites (p = 0.007. Based on our results we could conclude that acetate tape impression is a reliable method for diagnosing and monitoring therapy of dermatopathies caused by mites and can be used to replace the traditional deep skin scraping method. In addition, since it is less traumatic for the dog, this method shows more acceptance by the owner.

  7. Prevalence and Characteristics of Streptococcus canis Strains Isolated from Dogs and Cats

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    P. Lysková

    2007-01-01

    Full Text Available To determine the prevalence of Streptococcus canis in dogs and cats, a total of 926 swabs were examined bacteriologically in the period from 2003 to 2005. Eighty-six isolates obtained from various anatomical locations were further characterized for their phenotypic properties. The most frequently isolated biotype produced phosphatase, leucine amidopeptidase, arginine dihydrolase, alpha-D- and beta-D-galactosidase and fermented lactose and ribose. Additional identification by species-specific amplification of the 16S-23S rRNA intergenic spacer region was consistent with S. canis. All isolates were susceptible to penicillin G and ampicillin. The least effective antimicrobial agent was found to be tetracycline (only 33.8% of susceptible strains.

  8. ANTIFUNGAL ACTIVITY OF Cymbopogon nardus (L. Rendle (CITRONELLA AGAINST Microsporum canis FROM ANIMALS AND HOME ENVIRONMENT

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    Isis Regina Grenier CAPOCI

    2015-12-01

    Full Text Available Dermatophytosis is a common zoonosis in urban centers. Dogs and cats have played an important role as its disseminators. Environmental decontamination is essential for the prevention of its propagation to humans and animals. However, sanitizers or disinfectants with antifungal activity, currently available, have high toxicity. The present study evaluated the in vitro effects of an extract of citronella (Cymbopogon nardus on 31 Microsporum canis isolates from animals and home environments. Susceptibility tests were performed based on document M38-A2 (2008 of the Clinical and Laboratory Standards Institute with modifications for natural products. Although susceptibility variation was observed between the fungus tested, the concentrations that inhibited the growth of 50 and 90% of the microorganisms were low (19.5 and 78 µg/mL, respectively. Thus, this citronella extract showed potent fungistatic and fungicide activities against M. canis isolated from animals and home environments. Therefore, it could be an alternative for dermatophytosis prophylaxis in the home environment.

  9. CANIS LUPUS (MAMMALIA, CANIDAE FROM THE LATE PLEISTOCENE DEPOSIT OF AVETRANA (TARANTO, SOUTHERN ITALY

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    DAVIDE F.BERTÈ

    2014-11-01

    Full Text Available Here we described the remains of Canis lupus from the bed 8 of Avetrana karst filling (Late Pleistocene; Taranto, Southern Italy. The studied specimens are larger than those collected from the early Late Pleistocene Apulian localities and those referred to the recent Italian wolf. Moreover, the remains from Avetrana are morphometrically close to Canis lupus maximus from France and to C. lupus collected from Central and Northern Italian localities, chronologically related to MIS 2 and MIS 3. Morphologically, the studied specimens slightly differ from both C. l. maximus and other Pleistocene Apulian wolves. The dimensional differences between the Avetrana wolves and those collected from the other early Late Pleistocene Apulian localities could be explained through a spread of a large-sized morphotype from the Northern Italy.

  10. Presence of Leishmania and Brucella Species in the Golden Jackal Canis aureus in Serbia

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    Duško Ćirović

    2014-01-01

    Full Text Available The golden jackal Canis aureus occurs in south-eastern Europe, Asia, the Middle East, the Caucasus, and Africa. In Serbia, jackals neared extinction; however, during the last 30 years, the species started to spread quickly and to increase in number. Few studies in the past have revealed their potential role as carriers of zoonotic diseases. Animal samples were collected over a three-year period (01/2010–02/2013 from 12 sites all over Serbia. Of the tissue samples collected, spleen was chosen as the tissue to proceed; all samples were tested for Leishmania species and Brucella species by real-time PCR. Of the 216 samples collected, 15 (6.9% were positive for Leishmania species, while four (1.9% were positive for B. canis. The potential epidemiologic role of the golden jackal in carrying and dispersing zoonotic diseases in Serbia should be taken under consideration when applying surveillance monitoring schemes.

  11. Investigations of prevalence of antibodies to B.canis in stray dogs in territory of Belgrade

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    Radojičić Sonja

    2006-01-01

    Full Text Available The paper covers investigations of stray dogs in the territory of the city of Belgrade. A total of 184 blood serum samples were examined for the presence of antibodies specific to Brucella canis. The method of slow agglutination in a test tube with 2- mercaptoethanol was used in the diagnostic procedure. Of the 184 examined serums, 49 (26.63% had a titer of 1/50, 25 serums had a titer of 1/100 (13.58%, while 20 serums had a titer equal to or bigger than 1/200 (10.87%. Furthermore, 15 samples of full blood from serologiclly negative animals were also presented for isolation. The bacteriological finding for these samples was negative. The obtained results indicate that the number of seropositive stray dogs in the territory of Belgrade is extremely high and that 10.87% of the testes animals are definitely infected with Brucella canis.

  12. A molecular and parasitological survey of Hepatozoon canis in domestic dogs in Turkey.

    Science.gov (United States)

    Aktas, Munir; Özübek, Sezayi; Altay, Kürşat; Balkaya, İbrahim; Utuk, Armagan Erdem; Kırbas, Akın; Şimsek, Sami; Dumanlı, Nazir

    2015-04-30

    In this study, asymptomatic dogs in nine provinces of Turkey were surveyed to investigate the prevalence and intensity of Hepatozoon canis infection. DNA obtained from blood samples collected from 694 domestic dogs (243 stray, 288 shelter, and 163 pets) of both genders and varying ages were evaluated by polymerase chain reaction (PCR). In addition, 285 thin blood smears prepared from these blood samples were also evaluated for microscopic examination. Direct microscopy revealed Hepatozoon gamonts in the peripheral blood of three of 285 (1.0%; 95% confidence interval (CI): 0.21-3.04) tested. Using PCR, 155 of the 694 (22.3%; 95% CI: 19.28-25.61) were found to be positive for the presence of H. canis DNA. The prevalence of infection was higher in adult dogs (26.2%; 95% CI: 22.1-30.7) than young animals (16.4%; 95% CI: 12.2-21.3). Although the prevalence determined by PCR was higher in male dogs (24.5%; 95% CI: 19.6-29.9) than in female dogs (20.8%; 95% CI: 16.9-25.1), gender differences were not significant. Pet dogs had a lower prevalence of infection (10.4%; 95% CI: 6.2-16.2) compared to stray (26.3%; 95% CI: 20.9-32.3) and shelter dogs (25.7%; 95% CI: 20.7-31.1), but no significant association between stray and shelter dogs was found for the presence of the parasite. Partial sequences of the 18S ribosomal RNA (rRNA) gene shared 99-100% similarity with the corresponding H. canis isolates. This epidemiological survey revealed a high prevalence of H. canis in dogs from several provinces in Turkey, and it suggests that the age and origin are associated with the parasite. Copyright © 2015 Elsevier B.V. All rights reserved.

  13. Parasitological detection and molecular evidence of Hepatozoon canis from canines in Manila, Philippines

    OpenAIRE

    Baticados, Waren; Baticados,Waren; Carlos,; Villarba,; Subiaga,; Carlos Sr.,Enrique; Baticados,Abigail

    2011-01-01

    Abigail M Baticados1, Waren N Baticados1, Enrique T Carlos2, Sixto MEAS Carlos2, Lorelie A Villarba1, Sherlyn G Subiaga1, Jomarte M Magcalas11Department of Veterinary Paraclinical Sciences, College of Veterinary Medicine, University of the Philippines Los Baños, Laguna, Philippines; 2Makati Dog and Cat Hospital (MDCH), Makati City, PhilippinesAbstract: Hepatozoon canis infection in canines is allegedly an underreported disease in the Philippines. In over the past four decades, ther...

  14. Molecular identification of Hepatozoon canis in dogs from Campo Grande, Mato Grosso do Sul, Brazil.

    Science.gov (United States)

    Ramos, Carlos Alberto do Nascimento; Babo-Terra, Verônica Jorge; Pedroso, Thatianna Camillo; Souza Filho, Antônio Francisco; de Araújo, Flábio Ribeiro; Cleveland, Herbert Patric Kellermann

    2015-01-01

    The aim of this study was to investigate the occurrence of Hepatozoon species infecting dogs in the municipality of Campo Grande, Mato Grosso do Sul (MS), Brazil, using blood samples (n = 165) drawn from dogs. The species Hepatozoon canis was identified in 3.63% of the tested animals using molecular tools. Further studies are needed to determine the clinical relevance of this infection and the main arthropod vectors involved in its transmission.

  15. Oocysts of Hepatozoon canis in Rhipicephalus (Boophilus) microplus collected from a naturally infected dog.

    Science.gov (United States)

    de Miranda, Renata Lima; de Castro, Jacqueline Ribeiro; Olegário, Maria Marlene Martins; Beletti, Marcelo Emílio; Mundim, Antonio Vicente; O'Dwyer, Lucia Helena; Eyal, Osnat; Talmi-Frank, Dalit; Cury, Márcia Cristina; Baneth, Gad

    2011-05-11

    Canine hepatozoonosis is a tick-borne disease caused by protozoans of the genus Hepatozoon. Several tick species have been implicated as potential vectors. Therefore, extensive studies are needed to determine the 'natural' endemic cycle of this parasite. This paper presents the first report of the presence of Hepatozoon canis oocysts in Rhipicephalus (Boophilus) microplus collected from an infected dog. Copyright © 2011 Elsevier B.V. All rights reserved.

  16. Seroprevalence of Ehrlichia canis, Ehrlichia chaffeensis and Ehrlichia ewingii in dogs in North America

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    Beall Melissa J

    2012-02-01

    Full Text Available Abstract Background This study evaluated the exposure of dogs to three different Ehrlichia spp. in the south and central regions of the United States where vector-borne disease prevalence has been previously difficult to ascertain, particularly beyond the metropolitan areas. Methods Dog blood samples (n = 8,662 were submitted from 14 veterinary colleges, 6 private veterinary practices and 4 diagnostic laboratories across this region. Samples were tested for E. canis, E. chaffeensis and E. ewingii specific antibodies using peptide microtiter ELISAs. Results Overall, E. canis, E. chaffeensis and E. ewingii seroprevalence was 0.8%, 2.8%, and 5.1%, respectively. The highest E. canis seroprevalence (2.3% was found in a region encompassing Arkansas, Louisiana, Oklahoma, Tennessee and Texas. E. chaffeensis seroreactivity was 6.6% in the central region (Arkansas, Kansas, Missouri, and Oklahoma and 4.6% in the southeast region (Georgia, Maryland, North Carolina, South Carolina, Tennessee and Virginia. Seroreactivity to E. ewingii was also highest in the central region (14.6% followed by the southeast region (5.9%. The geospatial pattern derived from E. chaffeensis and E. ewingii seropositive samples was similar to previous reports based on E. chaffeensis seroreactivity in white-tailed deer and the distribution of human monocytic ehrlichiosis (HME cases reported by the CDC. Conclusions The results of this study provide the first large scale regional documentation of exposure to E. canis, E. chaffeensis and E. ewingii in pet dogs, highlighting regional differences in seroprevalence and providing the basis for heightened awareness of these emerging vector-borne pathogens by veterinarians and public health agencies.

  17. In vitro effect of Chrysosporium indicum and Chrysosporium keratinophylum on Toxocara canis eggs.

    Science.gov (United States)

    Bojanich, María V; Basualdo, Juan A; Giusiano, Gustavo

    2017-12-05

    The degree of antagonism exercised by fungi on geohelminth development varies according to the morphological alterations caused by different fungal species. Saprophytic fungi may exert ovicidal or ovistatic effects. The aim of this study was to apply scanning electron microscopy (SEM) to observe the action of two soil saprophytic species of Chrysosporium (C. indicum and C. keratinophylum) on Toxocara canis eggs. The fungal strains to be tested were incubated for 28 days at 28°C in 2% water agar with a suspension of unembryonated T. canis eggs. A suspension of T. canis eggs in 2% water agar was used as control group. The assay was done in triplicate for each fungus and the control group. SEM observations were performed on the 4th, 7th, 14th, 21st, and 28th day after inoculation. The effect of the fungi on eggs was evaluated in accordance with the alterations observed on the surface and the changes in the normal characteristics of the eggs. Hyphae around the eggs, appresoria penetrating the shell and changes in the typical egg membrane were observed in this assay. Type 3 effect (alterations that occur both in the embryo and the shell, and hyphal penetration of the eggs) was the prevalent effect. SEM allowed us to observe clearly the morphological alterations in T. canis eggs due to the effect of C. indicum and C. keratinophylum. Both saprophytic species of Chrysosporium alter the egg structure and alterations increase as exposure increases. Copyright © 2017 Asociación Argentina de Microbiología. Publicado por Elsevier España, S.L.U. All rights reserved.

  18. Restricted evaluation of Trichodectes canis (Phthiraptera: Trichodectidae detection methods in Alaska gray wolves

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    Theresa M. Woldstad

    2014-12-01

    Full Text Available Trichodectes canis (Phthiraptera: Trichodectidae was first documented on Alaska (USA gray wolves (Canis lupus on the Kenai Peninsula in 1981. In subsequent years, numerous wolves exhibited visually apparent, moderate to severe infestations. Currently, the Alaska Department of Fish and Game utilizes visual inspection, histopathology, and potassium hydroxide (KOH hide digestion for T. canis detection. Our objective was to determine optimal sampling locations for T. canis detection. Wolf hides were subjected to lice enumeration using KOH hide digestion. Thirty nine of the 120 wolves examined had lice. Of these 39, total louse burdens ranged from 14 to an extrapolated 80,000. The hides of 12 infested animals were divided into 10 cm by 10 cm subsections and the lice enumerated on a subsection from each of four regions: neck; shoulder; groin; and rump. Combining the data from these 12 wolves, the highest mean proportions of the total louse burdens on individual wolves were found on the rump and differed significantly from the lowest mean proportion on the neck. However, examination of the four subsections failed to detect all infested wolves. Hides from 16 of the 39 infested animals were cut into left and right sides, and each side then cut into four, approximately equal sections: neck and shoulder; chest; abdomen; and rump. Half hides were totally digested from 11 wolves, and whole hides from 5. For these 21 half hides, the highest mean proportions of total louse burdens were found on the rump, and this section had the highest sensitivity for louse detection, regardless of burden. However, removal of this large section from a hide would likely be opposed by hunters and trappers.

  19. Long-distance dispersal connects Dinaric-Balkan and Alpine grey wolf (Canis lupus) populations

    OpenAIRE

    Ražen, Nina; Kljun, Franc; Kos, Ivan; Krofel, Miha; Luštrik, Roman; Majić Skrbinšek, Aleksandra; Potočnik, Hubert

    2017-01-01

    In the last two centuries, persecution and deforestation caused grey wolf Canis lupus populations in Europe to decline. Recently, their numbers started to recover although most populations still remain isolated from one another. This study presents the first documented evidence of the successful reconnection of the Dinaric-Balkan and the Alpine wolf populations via long distance dispersal and subsequent reproduction. A young male wolf radiocollared in the Dinaric Mountains in July...

  20. Loop-mediated isothermal amplification as a reliable assay for Toxocara canis infection in pet dogs.

    Science.gov (United States)

    Khoshakhlagh, Paria; Spotin, Adel; Mahami-Oskouei, Mahmoud; Shahbazi, Abbas; Ozlati, Maryam

    2017-09-01

    Keeping of infected dogs as pet results in the potential transmission risk factors for shedding helminthic infections such as toxocariasis. Lack of accurate identification of Toxocara canis eggs in non-dewormed infected pet dogs remains a diagnostic concern among researchers. In this study, dog owners were asked to fill up a questionnaire regarding their pets and their attitude towards the deworming regimen. One hundred faecal samples were collected from pet dogs (Northwest Iran) and were subsequently identified by the ZnSo4 flotation technique, PCR and loop-mediated isothermal amplification (LAMP) assays. The DNA of the recovered T. canis eggs was then extracted and amplified by LAMP and PCR. Furthermore, ITS2 amplicons were sequenced for appraisal of the phylogenetic analysis. Nine, 5 and 11% of T. canis infections were identified by microscopy, PCR and LAMP, respectively. It was detected that LAMP was 10 times (10 -10 to 10 -13  g/μl) more sensitive than PCR (10 -10 to 10 -12  g/μl). The kappa value between LAMP and PCR indicated a faint concurrence (0.463). The kappa coefficient between LAMP and flotation technique indicated a strong agreement (0.667). The highest infection rate (n = 11) was detected in non-dewormed pet dogs, particularly those less than 3 months old (P canis eggs in infected pet dogs. It was proposed that the dog holder's awareness is insufficient to implement regular deworming schedules. Additionally, regional policymakers should broadly revise anthelmintic treatment guidelines.