1,201 research outputs found
On the Anatomy of Prosthecocotyle torulosa (Linstow) and Prosthecocotyle heteroclita (Dies.)
In the Report on the Entozoa collected by H.M.S. "Challengerâ Dr O. von Linstow described two new tapeworms, which he named Tetrabothrium torulosum and T. auriculatum. The resemblance of the head of T. auriculatum with that of Prosthecocotyle Forsteri described by Monticelli seemed to me to indicate that the Tetrabothrium described by Linstow probably belonged to the genus Prosthecocotyle. Through the kindness of Sir John Murray, I received from the British Museum the original specimens for inspection, for which I wish to express here my warmest thanks. The following lines give the results of my examination; but before entering upon the description, let me say something on the systematic position of these two animals. As I have already remarked, Prof. Monticelli has rightly erected a new genus named Prosthecocotyle for the tapeworm TĆnia Forsteri, Krefft. To this genus belongs, besides P. Forsteri, other parasites of birds which have been placed in the genera TĆnia, Tetrabothrium, Amphoterocotyle, BothridiotĆnia, Bothriocephalus. According to my researches the following species belong to the genus Prosthecocotyle:â 1. P. Forsteri (Krefft), (syn. TĆnia Forsteri, Krefft), from Delphinus Forsteri (Gray) and Delphinus delphinus, L. 2. P. Monticellii, Fuhrmann (syn. TĆnia erostris, ex parte, BothridiotĆnia erostris, var. minor, Lönnberg), from Fulmarus glacialis, L. 3. P. umbrella, Fuhrmann, from Diomedea sp. (?). 4. P. torulosa (Linstow), (syn. Tetrabothrium torulosum, Linstow), from Diomedea brachyura, Tem
Detailed analysis of Balmer lines in cool dwarf stars
An analysis of H alpha and H beta spectra in a sample of 30 cool dwarf and
subgiant stars is presented using MARCS model atmospheres based on the most
recent calculations of the line opacities. A detailed quantitative comparison
of the solar flux spectra with model spectra shows that Balmer line profile
shapes, and therefore the temperature structure in the line formation region,
are best represented under the mixing length theory by any combination of a low
mixing-length parameter alpha and a low convective structure parameter y. A
slightly lower effective temperature is obtained for the sun than the accepted
value, which we attribute to errors in models and line opacities. The programme
stars span temperatures from 4800 to 7100 K and include a small number of
population II stars. Effective temperatures have been derived using a
quantitative fitting method with a detailed error analysis. Our temperatures
find good agreement with those from the Infrared Flux Method (IRFM) near solar
metallicity but show differences at low metallicity where the two available
IRFM determinations themselves are in disagreement. Comparison with recent
temperature determinations using Balmer lines by Fuhrmann (1998, 2000), who
employed a different description of the wing absorption due to self-broadening,
does not show the large differences predicted by Barklem et al. (2000). In
fact, perhaps fortuitously, reasonable agreement is found near solar
metallicity, while we find significantly cooler temperatures for low
metallicity stars of around solar temperature.Comment: 17 pages, 9 figures, to appear in A&
Long-Term Multiwavelength Studies of High-Redshift Blazar 0836+710
Aims. The observation of gamma -ray flares from blazar 0836+710 in 2011,
following a period of quiescence, offered an opportunity to study correlated
activity at different wavelengths for a high-redshift (z=2.218) active galactic
nucleus. Methods. Optical and radio monitoring, plus Fermi-LAT gamma-ray
monitoring provided 2008-2012 coverage, while Swift offered auxiliary optical,
ultraviolet, and X-ray information. Other contemporaneous observations were
used to construct a broad-band spectral energy distribution. Results. There is
evidence of correlation but not a measurable lag between the optical and
gamma-ray flaring emission. On the contrary, there is no clear correlation
between radio and gamma-ray activity, indicating radio emission regions that
are unrelated to the parts of the jet that produce the gamma-rays. The
gamma-ray energy spectrum is unusual in showing a change of shape from a power
law to a curved spectrum when going from the quiescent state to the active
state.Comment: 11 pages, 10 figures, Accepted for publication in A&
Flaring Activity from 0836+710 (4C +71.07): What Can We Learn With Limited Multiwavelength Coverage?
After a long period of quiescence in \gamma-rays, blazar 0836+710 (4C +71.07)
flared in the Spring of 2011. We found only limited multiwavelength coverage of
the source. An indication of correlated optical / \gamma-ray variability is not
surprising for a Flat Spectrum Radio Quasar (FSRQ) like this one. Radio
observations at high frequencies, however, had seen a flare in 2010, well
offset from possible \gamma-ray activity. The 2011 \gamma-ray activity comes
during a period of rising radio emission, a pattern that has been seen since
the EGRET era.Comment: 5 pages,2 figures, proceedings of 'Fermi & Jansky:Our Evolving
Understanding of AGN
Detailed Analysis of Nearby Bulgelike Dwarf Stars III. Alpha and Heavy-element abundances
The present sample of nearby bulgelike dwarf stars has kinematics and
metallicities characteristic of a probable inner disk or bulge origin. Ages
derived by using isochrones give 10-11 Gyr for these stars and metallicities
are in the range -0.80< [Fe/H]< +0.40. We calculate stellar parameters from
spectroscopic data, and chemical abundances of Mg, Si, Ca, Ti, La, Ba, Y, Zr
and Eu are derived by using spectrum synthesis.
We found that [alpha-elements/Fe] show different patterns depending on the
element. Si, Ca and Ti-to-iron ratios decline smoothly for increasing
metallicities, and follow essentially the disk pattern. O and Mg, products of
massive supernovae, and also the r-process element Eu, are overabundant
relative to disk stars, showing a steeper decline for metallicities [Fe/H] >
-0.3 dex. [s-elements/Fe] roughly track the solar values with no apparent trend
with metallicity for [Fe/H] < 0, showing subsolar values for the metal rich
stars. Both kinematical and chemical properties of the bulgelike stars indicate
a distinct identity of this population when compared to disk stars.Comment: 21 pages, 9 figures, to appear in Ap
An Augmented Reality system for the treatment of phobia to small animals viewed via an optical see-through HMD. Comparison with a similar system viewed via a video see-through
This article presents an optical see-through (OST) Augmented Reality system for the treatment of phobia to small animals. The technical characteristics of the OST system are described, and a comparative study of the sense of presence and anxiety in a nonphobic population (24 participants) using the OST and an equivalent video see-though (VST) system is presented. The results indicate that if all participants are analyzed, the VST system induces greater sense of presence than the OST system. If the participants who had more fear are analyzed, the two systems induce a similar sense of presence. For the anxiety level, the two systems provoke similar and significant anxiety during the experiment. © Taylor & Francis Group, LLC.Juan, M.; Calatrava, J. (2011). An Augmented Reality system for the treatment of phobia to small animals viewed via an optical see-through HMD. Comparison with a similar system viewed via a video see-through. International Journal of Human-Computer Interaction. 27(5):436-449. doi:10.1080/10447318.2011.552059S436449275Azuma, R. and Bishop, G. Improving static and dynamic registration in an optical see-through HMD. Proceedings of 21st Annual Conference on Computer Graphics and Interactive techniques (SIGGRAPH'94). pp.197â204.Bimber, O., & Raskar, R. (2005). Spatial Augmented Reality. doi:10.1201/b10624Botella, C., Quero, S., Banos, R. M., Garcia-Palacios, A., Breton-Lopez, J., Alcaniz, M., & Fabregat, S. (2008). Telepsychology and Self-Help: The Treatment of Phobias Using the Internet. CyberPsychology & Behavior, 11(6), 659-664. doi:10.1089/cpb.2008.0012Botella, C. M., Juan, M. C., Baños, R. M., Alcañiz, M., GuillĂ©n, V., & Rey, B. (2005). Mixing Realities? An Application of Augmented Reality for the Treatment of Cockroach Phobia. CyberPsychology & Behavior, 8(2), 162-171. doi:10.1089/cpb.2005.8.162Carlin, A. S., Hoffman, H. G., & Weghorst, S. (1997). Virtual reality and tactile augmentation in the treatment of spider phobia: a case report. Behaviour Research and Therapy, 35(2), 153-158. doi:10.1016/s0005-7967(96)00085-xGarcia-Palacios, A., Hoffman, H., Carlin, A., Furness, T. ., & Botella, C. (2002). Virtual reality in the treatment of spider phobia: a controlled study. Behaviour Research and Therapy, 40(9), 983-993. doi:10.1016/s0005-7967(01)00068-7Genc, Y., Tuceryan, M., & Navab, N. (s. f.). Practical solutions for calibration of optical see-through devices. Proceedings. International Symposium on Mixed and Augmented Reality. doi:10.1109/ismar.2002.1115086Hoffman, H. G., Garcia-Palacios, A., Carlin, A., Furness III, T. A., & Botella-Arbona, C. (2003). Interfaces That Heal: Coupling Real and Virtual Objects to Treat Spider Phobia. International Journal of Human-Computer Interaction, 16(2), 283-300. doi:10.1207/s15327590ijhc1602_08Juan, M. C., Alcaniz, M., Monserrat, C., Botella, C., Banos, R. M., & Guerrero, B. (2005). Using Augmented Reality to Treat Phobias. IEEE Computer Graphics and Applications, 25(6), 31-37. doi:10.1109/mcg.2005.143Juan, M. C., Baños, R., Botella, C., PĂ©rez, D., AlcanĂiz, M., & Monserrat, C. (2006). An Augmented Reality System for the Treatment of Acrophobia: The Sense of Presence Using Immersive Photography. Presence: Teleoperators and Virtual Environments, 15(4), 393-402. doi:10.1162/pres.15.4.393Kato, H., & Billinghurst, M. (s. f.). Marker tracking and HMD calibration for a video-based augmented reality conferencing system. Proceedings 2nd IEEE and ACM International Workshop on Augmented Reality (IWARâ99). doi:10.1109/iwar.1999.803809Nash, E. B., Edwards, G. W., Thompson, J. A., & Barfield, W. (2000). A Review of Presence and Performance in Virtual Environments. International Journal of Human-Computer Interaction, 12(1), 1-41. doi:10.1207/s15327590ijhc1201_1Owen, C. B., Ji Zhou, Tang, A., & Fan Xiao. (s. f.). Display-Relative Calibration for Optical See-Through Head-Mounted Displays. Third IEEE and ACM International Symposium on Mixed and Augmented Reality. doi:10.1109/ismar.2004.28Ăzbek, C., Giesler, B. and Dillmann, R. Jedi training: Playful evaluation of head-mounted augmented reality display systems. SPIE Conference Medical Imaging. Vol. 5291, pp.454â463.Renaud, P., Bouchard, S., & Proulx, R. (2002). Behavioral avoidance dynamics in the presence of a virtual spider. IEEE Transactions on Information Technology in Biomedicine, 6(3), 235-243. doi:10.1109/titb.2002.802381Schwald, B. and Laval, B. An Augmented Reality system for training and assistance to maintenance in the industrial context. International Conference in Central Europe on Computer Graphics, Visualization and Computer Vision. pp.425â432.Slater, M., Usoh, M., & Steed, A. (1994). Depth of Presence in Virtual Environments. Presence: Teleoperators and Virtual Environments, 3(2), 130-144. doi:10.1162/pres.1994.3.2.130Szymanski, J., & OâDonohue, W. (1995). Fear of Spiders Questionnaire. Journal of Behavior Therapy and Experimental Psychiatry, 26(1), 31-34. doi:10.1016/0005-7916(94)00072-
Exploring the Local Milky Way: M Dwarfs as Tracers of Galactic Populations
We have assembled a spectroscopic sample of low-mass dwarfs observed as part
of the Sloan Digital Sky Survey along one Galactic sightline, designed to
investigate the observable properties of the thin and thick disks. This sample
of ~7400 K and M stars also has measured ugriz photometry, proper motions, and
radial velocities. We have computed UVW space motion distributions, and
investigate their structure with respect to vertical distance from the Galactic
Plane. We place constraints on the velocity dispersions of the thin and thick
disks, using two-component Gaussian fits. We also compare these kinematic
distributions to a leading Galactic model. Finally, we investigate other
possible observable differences between the thin and thick disks, such as
color, active fraction and metallicity.Comment: 11 pages, 12 figures, Accepted by A
The N2K Consortium. II. A Transiting Hot Saturn Around HD 149026 With a Large Dense Core
Doppler measurements from Subaru and Keck have revealed radial velocity
variations in the V=8.15, G0IV star HD 149026 consistent with a Saturn-Mass
planet in a 2.8766 day orbit. Photometric observations at Fairborn Observatory
have detected three complete transit events with depths of 0.003 mag at the
predicted times of conjunction. HD 149026 is now the second brightest star with
a transiting extrasolar planet. The mass of the star, based on interpolation of
stellar evolutionary models, is 1.3 +/- 0.1 solar masses; together with the
Doppler amplitude, K=43.3 m s^-1, we derive a planet mass Msin(i)=0.36 Mjup,
and orbital radius of 0.042 AU. HD 149026 is chromospherically inactive and
metal-rich with spectroscopically derived [Fe/H]=+0.36, Teff=6147 K, log g=4.26
and vsin(i)=6.0 km s^-1. Based on Teff and the stellar luminosity of 2.72 Lsun,
we derive a stellar radius of 1.45 Rsun. Modeling of the three photometric
transits provides an orbital inclination of 85.3 +/- 1.0 degrees and (including
the uncertainty in the stellar radius) a planet radius of 0.725 +/- 0.05 Rjup.
Models for this planet mass and radius suggest the presence of a ~67 Mearth
core composed of elements heavier than hydrogen and helium. This substantial
planet core would be difficult to construct by gravitational instability.Comment: 25 pages, 5 figures, accepted by the Astrophysical Journa
Multi-frequency VLBA study of the blazar S5 0716+714 during the active state in 2004: I. Inner jet kinematics
We observed the blazar \object{0716+714} with the
VLBA during its active state in 2003-2004. In this paper we discuss
multi-frequency analysis of the inner jet (first 1 mas) kinematics. The
unprecedentedly dense time sampling allows us to trace jet components without
misidentification and to calculate the component speeds with good accuracy. In
the smooth superluminal jet we were able to identify and track three components
over time moving outwards with relatively high apparent superluminal speeds
(8.5-19.4 ), which contradicts the hypothesis of a stationary oscillating
jet in this source. Component ejections occur at a relatively high rate (once
in two months), and they are accompanied by mm-continuum outbursts.
Superluminal jet components move along wiggling trajectories, which is an
indication of actual helical motion. Fast proper motion and rapid decay of the
components suggest that this source should be observed with the VLBI at a rate
of at least once in one or two months in order to trace superluminal jet
components without confusion.Comment: 4 pages, 3 figures, Astronomy & Astrophysics Letter, language
corrections adde
Highly charged ion X-rays from Electron-Cyclotron Resonance Ion Sources
Radiation from the highly-charged ions contained in the plasma of
Electron-Cyclotron Resonance Ion Sources constitutes a very bright source of
X-rays. Because the ions have a relatively low kinetic energy ( eV)
transitions can be very narrow, containing only small Doppler broadening. We
describe preliminary accurate measurements of two and three-electron ions with
Z=16--18. We show how these measurement can test sensitively many-body
relativistic calculations or can be used as X-ray standards for precise
measurements of X-ray transitions in exotic atoms
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