Large Opening Angle Research Articles

Esistenza del modo O in piastre tridimensionali con fori circolari ed ellittici soggette a modo II

On the mode O existence in three-dimensional plates weakened by circular and elliptical holes under mode II loading It is known for long time that in a cracked plate subjected to anti-symmetric plane loading, the Poisson’s effect leads to the generation of a coupled out-of-plane singular mode (Mode O). Recent theoretical and numerical analyses have shown that this effect is present also in plates weakened by pointed V-notches and might play a role in failure initiation phenomena in plates under mode II loading particularly in the presence of large opening angle. Since the degree of singularity characterising the mode O is greater than that of mode II, the mutual incidence of the two modes depends on the component size. Dealing with circular and elliptic holes, the presence or not of the out-of-plane mode has never been discussed in the literature. The main aim of this work is to demonstrate the existence of a three-dimensional effect tied to mode O. On the basis of a large bulk of numerical results the following conclusions can be drawn: - An out-of-plane mode is present in plates weakened by U-notches and subjected to Mode II loading, as previously demonstrated for plates weakened by cracks and pointed V-notches; its intensity is not negligible also for finite values of the notch radius. - Out-of-plane mode results in a shear stress distribution symmetric with respect to the mid-plane. The intensity of this stress component strongly depends on the Poisson’s ratio. It increases as increases. - The strain energy density averaged on a given control volume which should, in principle, be material dependent is a parameter suitable for the natural of capture all three dimensional effects occurring through the plate thickness. It is surely a powerful tool in practical cases where the role played by three-dimensionality is not negligible, or is not known in detail.

Evidence for ultra-fast outflows in radio-quiet AGNs

<i>Context. <i/>Blue-shifted Fe K absorption lines have been detected in recent years between 7 and 10 keV in the X-ray spectra of several radio-quiet AGNs. The derived blue-shifted velocities of the lines can often reach mildly relativistic values, up to 0.2–0.4c. These findings are important because they suggest the presence of a previously unknown massive and highly ionized absorbing material outflowing from their nuclei, possibly connected with accretion disk winds/outflows.<i>Aims. <i/>The scope of the present work is to statistically quantify the parameters and incidence of the blue-shifted Fe K absorption lines through a uniform analysis on a large sample of radio-quiet AGNs. This allows us to assess their global detection significance and to overcome any possible publication bias.<i>Methods. <i/>We performed a blind search for narrow absorption features at energies greater than 6.4 keV in a sample of 42 radio-quiet AGNs observed with <i> XMM-Newton<i/>. A simple uniform model composed by an absorbed power-law plus Gaussian emission and absorption lines provided a good fit for all the data sets. We derived the absorption lines parameters and calculated their detailed detection significance making use of the classical F-test and extensive Monte Carlo simulations.<i>Results. <i/>We detect 36 narrow absorption lines on a total of 101 <i> XMM-Newton<i/> EPIC pn observations. The number of absorption lines at rest-frame energies higher than 7 keV is 22. Their global probability to be generated by random fluctuations is very low, less than 3 × 10<sup>-8<sup/>, and their detection have been independently confirmed by a spectral analysis of the MOS data, with associated random probability <i><<i/>10<sup>-7<sup/>. We identify the lines as Fe XXV and Fe XXVI K-shell resonant absorption. They are systematically blue-shifted, with a velocity distribution ranging from zero up to ~0.3c, with a peak and mean value at ~0.1c. We detect variability of the lines on both <i>EW<i/>s and blue-shifted velocities among different <i> XMM-Newton<i/> observations even on time-scales as short as a few days, possibly suggesting somewhat compact absorbers. Moreover, we find no significant correlation between the cosmological red-shifts of the sources and the lines blue-shifted velocities, ruling out any systematic contamination by local absorption. If we define ultra-fast outflows (UFOs) those highly ionized absorbers with outflow velocities higher than 10<sup>4<sup/> km s<sup>-1<sup/>, then the majority of the lines are consistent with being associated to UFOs and the fraction of objects with detected UFOs in the whole sample is at least ~35%. This fraction is similar for type 1 and type 2 sources. The global covering fraction of the absorbers is consequently estimated to be in the range <i>C<i/> <i>∼<i/> 0.4-0.6, thereby implying large opening angles.<i>Conclusions. <i/>From our systematic X-ray spectral analysis on a large sample of radio-quiet AGNs we have been able to clearly assess the global veracity of the blue-shifted Fe K absorption lines at <i>E<i/> <i>><i/> 7 keV and to overcome their publication bias. These lines indicate that UFOs are a rather common phenomenon observable in the central regions of these sources and they are probably the direct signature of AGN accretion disk winds/ejecta. The detailed photo-ionization modeling of these absorbers is presented in a companion paper.

TANAMI: tracking active galactic nuclei with austral milliarcsecond interferometry

We introduce the TANAMI program (Tracking Active Galactic Nuclei with Austral Milliarcsecond Interferometry) which is monitoring an initial sample of 43 extragalactic jets located south of -30 degrees declination at 8.4 GHz and 22 GHz since 2007. All aspects of the program are discussed. First epoch results at 8.4 GHz are presented along with physical parameters derived therefrom. We present first epoch images for 43 sources, some observed for the first time at milliarcsecond resolution. Parameters of these images as well as physical parameters derived from them are also presented and discussed. These and subsequent images from the TANAMI survey are available at http://pulsar.sternwarte.uni-erlangen.de/tanami/ We obtain reliable, high dynamic range images of the southern hemisphere AGN. All the quasars and BL Lac objects in the sample have a single-sided radio morphology. Galaxies are either double-sided, single-sided or irregular. About 28% of the TANAMI sample has been detected by LAT during its first three months of operations. Initial analysis suggests that when galaxies are excluded, sources detected by LAT have larger opening angles than those not detected by LAT. Brightness temperatures of LAT detections and non-detections seem to have similar distributions. The redshift distributions of the TANAMI sample and sub-samples are similar to those seen for the bright gamma-ray AGN seen by LAT and EGRET but none of the sources with a redshift above 1.8 have been detected by LAT.

Usefulness and limitations of computational models in aortic disease risk stratification

In risk stratification of aortic diseases such as aneurysm and aortic dissection, diameter is one parameter whose influence on the average aortic wall stress is directly described by the Laplace law. More advanced mechanical models can be used and may yield additional information, such as transmural stress distributions. The question then arises of how refined models need to be to provide clinicians with practical help. Two sets of finite element models were used. The relative roles of diameter, material stiffness, longitudinal stretch, blood pressure, wall thickness, and vessel curvature were explored using simplified aortic models for comparison with the Laplace law. The influences of the material properties nonlinearity and residual stress on the transmural stress distribution were investigated using an advanced aortic model including recent experimental findings in older humans. The Laplace law was confirmed as one effective, basic tool to assess the average wall stress in the aortic wall, both in the circumferential and longitudinal directions. However, the simplified models were sufficient to show that, as already reported in the literature, longitudinal stretch and vessel curvature have potentially equally strong or even stronger contributions to wall stress than the parameters included in the Laplace law. When the advanced model was used, and residual stress induced by large opening angles such as found in older subjects was introduced, the transmural stress gradient was found inverted compared with expectations, with the largest stresses now toward the adventitia. The results suggested that the intima may be increasingly shielded from higher stresses as one gets older, which might be protective against the initiation of dissection tears in the thoracic aorta. Biomechanical analysis of the aorta may be refined by using increasingly detailed computational models. Simplified models can readily improve on the Laplace law in the assessment of aortic wall stress, and as such, may already contribute to better risk stratification of aortic disease. Advanced models may also enhance our understanding of the mechanistic aspects in the pathogenesis of aortic disease. However, their applicability in a patient-specific context may be limited by the large number of input data they require, some of which might stay out of the clinicians' reach.

On the Presence of the Out–of–Plane Singular Mode Induced by Plane Loading With KII = KI = 0

Previous studies by a number of researchers demonstrated that in the case of a plane crack subjected to shear loading conditions characterized by a remote stress intensity factor, KII, a three-dimensional singular mode (called mode O or out-of-plane mode) develops at the crack tip. This singular mode occurs due to the primary shear loading and Poisson’s effect. Similar to mode III, the O-mode is associated with the transverse shear stress components. Recent theoretical and numerical studies have also demonstrated a strong presence of this singular mode in plates weakened by pointed V-notches. Therefore, it was suggested that O-mode can play an important role in fracture initiation, particularly at large opening angles (above 102.6°) when the applied mode II is non-singular.

Effect of opening angle on dilute-dense flow transition in two-dimensional granular flow

Computer simulations are performed to investigate the effect of opening angle on dilute-dense flow transition in a two-dimensional granular flow. Two methods, i.e. the fixed inflow rate and the fixed particle number, are adopted. Both results show that larger opening angle results in an increase of maximum outflow rate in dilute-dense flow transition when the opening angle is larger than zero. When granular flow keeps a dilute flow, the outflow rate is irrelative with the opening angle. When the flow becomes a dense flow, the dense flow rate inereases with opening angle increasing. Further studies show that the granules flow out with a higher velocity when the opening angle increases. The linear relationship between maximum outflow rate and granule flow velocity is observed.

Long-term continuous energy injection in the afterglow of GRB 060729

A long plateau phase and an amazing level of brightness have been observed in the X-ray afterglow of GRB 060729. This peculiar light curve is likely due to long-term energy injection in external shock. Here, we present a detailed numerical study of the energy injection process of magnetic dipole radiation from a strongly magnetized millisecond pulsar and model the multi-band afterglow observations. It is found that this model can successfully explain the long plateaus in the observed X-ray and optical afterglow light curves. The sharp break following the plateaus could be due to the rapid decline of the emission power of the central pulsar. At an even later time (∼ 5 × 10 6 s), an obvious jet break appears, which implies a relatively large half opening angle of θ ∼ 0.3 for the GRB ejecta. Due to the energy injection, the Lorentz factor of the outflow is still larger than two even at 107 s after the GRB trigger, making the X-ray afterglow of this burst detectable by Chandra even 642 d after the burst.

STREAMING CIRCUMNUCLEAR GAS OF THE SEYFERT 2 GALAXY NGC 5728

We investigated the circumnuclear region of the Seyfert 2 galaxy NGC 5728, using the CFHT 3.6 m OASIS <TEX>$[S_{II}]$</TEX>, <TEX>$[O_{III}]$</TEX> & <TEX>$H\beta$</TEX> spectral images complemented with the IUE spectra. The physical condition of the circumnuclear zone has been derived: the gas density (indicated by <TEX>$[S_{II}]$</TEX>6716/31 ratio) around the C core is generally similar to that around the NW core, i.e., <TEX>$\sim500cm^{-3}$</TEX>. However, there appears to be evidence of a higher density shell in front of the NW core, <TEX>$\sim10^4cm^{-3}$</TEX> at -250 km <TEX>$s^-1$</TEX>. The IUE <TEX>$Si_{III}$</TEX>]1892/<TEX>$C_{III}$</TEX>]1909 ratio implies a possible presence of a broad emission region of gas densities of <TEX>$\sim10^{10}cm^{-3}$</TEX>. The SE cone and surrounding area show several prominent features, while the NW cone does not show any particular structure: we identified three prominent blobs in the SE cone and one possible candidate in the NW cone. The outflow activities exist within the relatively large conic opening angle. We discussed the possibility of inflow or outflow activities of blobs found in the circumnuclear region of NGC 5728. The gas around two cores, two cones, and several blobs, is likely to be excited by the AGN hot source(s).

Increase in Opening Angle in Hypertension Off-Loads the Intimal Stress: A Simulation Study

The stress distribution in the vessel wall has important bearing on vascular function including intima, media, and adventitia. The residual strain in the vessel wall has been thought to largely normalize the transmural stress distribution with slightly higher values at the intima. In hypertension, the compensatory increase in opening angle is thought to maintain a uniform stress distribution. We have recently shown that the circumferential stress at adventitia may exceed that at intima at physiological loading due to large opening angle (OA) in normal porcine coronary arteries. The objective of this study was to show that increases in opening angle subsequent hypertension can further shift the stress from the intima to the adventitia. The change in stress distribution during acute hypertension was calculated using available data on the changes in vessel geometry, material property, and internal pressure during hypertension. It was found that the increase in OA following acute hypertension off-loads the stress from intima to adventitia, therefore, relieving some of the stress increase in the intimal layer induced by the sudden pressure increase. This has important implications for hypertension where it may shift the excessive stress from the inner layer to the outer layer. This may be a protective mechanism for the intima layer in hypertension.

Breakdown of Lorentz invariance for spin-1/2particle motion in curved space-time with applications to muon decay

This paper explores the properties of the Pauli-Lubanski spin vector for the general motion of spin-1/2 particles in curved space-time. Building upon previously determined results in flat space-time, it is shown that the associated Casimir scalar for spin possesses both gravitational contributions and frame-dependent contributions due to noninertial motion, where the latter represents a possible quantum violation of Lorentz invariance that becomes significant at the Compton wavelength scale. When applied to muon decay near the event horizon of a microscopic Kerr black hole, it is shown that its differential cross section is strongly affected by curvature, with particular sensitivity to changes in the black hole's spin angular momentum. In the absence of curvature, the noninertial contributions to the decay spectrum are also identified and explored in detail, where its potential for observation is highest for large electron opening angles. It is further shown how possible contributions to noncommutative geometry can emerge from within this formalism at some undetermined length scale. Surprisingly, while the potential exists to identify noncommutative effects in muon decay, the relevant terms make no contribution to the decay spectrum, for reasons which remain unknown.

An X-Ray Study of Lobe-Dominated Radio-Loud Quasars with XMM-Newton

We report on our results of X-ray spectral analysis for a sample of radio-loud quasars covering a wide range of the radio core-dominance Parameter, R, from core-dominated to lobe-dominated objects, using data obtained mostly with the XMM-Newton Observatory. We find that the spectral shape of the underlying power-law continuum is flat even for the lobe-dominated objects (average photon index similar to 1.5), indistinguishable from that of core-dominated quasars. For lobe-dominated objects, contribution of X-rays from the jets is expected to be very small based on previous unification schemes, more than one order of magnitude lower than the observed X-ray luminosities. Assuming that radio-loud quasars follow the same X-ray-UV/optical luminosity relation for the disk-corona. emission as found for radio-quiet quasars, we estimate the X-ray flux contributed by the disk-corona component from the optical/UV continuum. We find that neither the luminosity, nor the spectral shape, of the disk-corona X-ray emission can account for the bulk of the observed X-ray properties. Thus in lobe-dominated quasars, either the disk-corona X-ray emission is much enhanced in strength and flatter in spectral shape (photon index similar to 1.5) compared to normal radio-quiet quasars, or their jet X-ray emission is much enhanced compared to their weak radio core-jet emission. If the latter is the case, our result may imply that the jet emission in X-rays is less Doppler beamed than that in the radio. As a demonstrating example, we test this hypothesis by using a specific model in which the X-ray jet has a larger opening angle than the radio jet.

Microstructure and kinematics of H2O masers in the massive star-forming region IRAS 06061+2151

We have made multi-epoch very long baseline interferometer (VLBI) observations of H 2 O maser emission in the massive star-forming region IRAS 06061+2151 with the Japanese VLBI network (JVN) from 2005 May to 2007 October. The detected maser features are distributed within a 1 x 1 arcsec 2 area (2000 x 2000 au 2 at the source position) around the ultracompact H ii region seen in radio continuum emission. The bipolar morphology and expanding motion traced through their relative proper motions indicate that they are excited by an energetic bipolar outflow. Our three-dimensional model fitting has shown that the maser kinematical structure in IRAS 06061+2151 can be explained by a biconical outflow with a large opening angle (>50°). The position angle of the flow major axis coincides very well with that of the large-scale jet seen in 2.1 μm hydrogen emission. This maser geometry indicates the existence of dual structures composed of a collimated jet and a less collimated massive molecular flow. We have also detected a large velocity gradient in the southern maser group. This can be explained by a very small (on a scale of several tens of astronomical units) and clumpy (the density contrast by an order of magnitude or more) structure of the parental cloud. Such a structure may be formed by strong instability of the shock front or splitting of the high density core.

Spin Polarized Surface State of fcc Co/Cu(001) Studied by Spin- and Angle-resolved Photoelectron Spectroscopy

We have newly developed a retarding-type Mott spin detector for spin- and angle-resolved photoelectron (SARPE) spectroscopy. Detection of scattered electrons at the Au target in an appropriate energy-loss window with a large opening angle has helped us to increase the efficiency of the spin polarimeter. The SARPE spectroscopy equipped with the developed spin detector has been applied to the study of surface and bulk electronic structures of fcc Co thin films grown on Cu(001) surface. The improved efficiency has enabled us to obtain the spin-resolved spectra while the surface is kept clean. As a result, we have successfully resolved a negatively spin-polarized surface resonance state of fcc Co/Cu(001) at Γ− of the surface Brillouin zone. It has also been clarified that the surface resonance state is markedly influenced by a spin-orbit coupling.

A synchrotron self-Compton scenario for the very high energy γ-ray emission of the radiogalaxy M 87

M87 is the first extragalactic source detected in the TeV range that is not a blazar. With the increasing performances of ground-based Cherenkov telescopes, we can now probe the variability in the gamma-ray flux at small timescales, thus putting strong constraints on the size of the emitting zone. A modification of standard emission models of TeV blazars appears necessary to account for the gamma-ray observations despite this misalignment. We explain TeV gamma-ray spectra and fast variability of M87 by invoking an emission zone close to the central supermassive black hole, which is filled with several plasma blobs moving in the large opening angle of the jet formation zone. We develop a new multi-blob synchrotron self-Compton (SSC) model with emitting blobs beyond the Alfven surface in the jet, at a distance of about 100 r_g from the central engine. This model is explicitly adapted to deal with large viewing angles and moderate values of the Lorentz factor inferred from (general relativistic) magnetohydrodynamic models of jet formation. This scenario can account for the recent gamma-ray observations of M87 made by the High Energy Stereoscopic System (H.E.S.S.) telescope array. We find individual blob radii of about 10^{14} cm, which is compatible with the variability on timescales of days recently reported by the H.E.S.S. collaboration and is of the order of the black hole gravitational radius. Predictions of the very high energy emission for three other sources with extended optical or X-ray jet which could be misaligned blazars still with moderate beaming are presented for one Seyfert 2 radiogalaxy, namely Cen A, one peculiar BL Lac, PKS 0521-36, and one quasar, 3C 273.

Generation of thin and hollow beams by the axicon with a large open angle

We propose a method to produce diffraction-free thin and hollow beams. The method is based on Laguerre–Gaussian (LG) beams incident on a large open-angle axicon. We use the vector diffraction integrals and stationary phase method to deduce a simple and analytical formula of the propagating field of the linearly polarized LG beams through an axicon. The numerical results show that the hollow beams of whose diameter is in the order of the wavelength can be obtained by using the axicon with the refractive index n = 2 and the open angle α = 25°. These diffraction-free thin and hollow beams may be very useful to accurately trap and manipulate atoms. However, when the open angle is over large, the conversion efficiency from the LG beam to the diffraction-free hollow beam will decrease obviously.

A Pole-on Bipolar Outflow from the AGB Star WX Piscium

Abstract We report on H$_{2}$O masers around the asymptotic giant branch (AGB) star WX Piscium (WX Psc $=$ IRC $+$10011), observed with the Japanese VLBI Network (JVN) at three epochs during a span of 2 months. The H$_{2}$O maser spectrum of WX Psc consists of double peaks with a separation of $\sim$ 30 km s$^{-1}$ centered at the systemic velocity of the star. The maser features are found to split roughly in two concentrations separated by about 60 mas from north to south. The northern concentration involves both blueshifted and redshifted components from both of the double peaks, suggesting that it is near the star driving the outflow. The maser spatiokinematics is well approximated by a radial expansion of a thick shell, except for the blueshifted features in the southern concentration. The spatiokinematics is compared with a fan-shaped morphology found in near-infrared emission, suggesting the existence of a bipolar outflow. Two different models are proposed for explaining the observed maser proper motions: one is a biconically expanding flow with a large opening angle ($2\theta_{\rm cone}=$70${}^\circ$–120${}^\circ$); the other is a collimated outflow with precession. The complicated spatiokinematics of the H$_{2}$O maser features indicates that the star is currently in the process of launching a bipolar outflow in the final stage of the AGB phase, shaping a planetary nebula in the next stage.

Comparison of Iterative Deconvolution Algorithmsfor the Mapping of Acoustic Sources

The DAMAS2 algorithm is compared with several other Fourier-based deconvolution approaches. One is the Richardson-Lucy method, which is widely used for the deconvolution of astronomical images. The second is a modified gradient-type NNLS approach, where spectral procedures are implemented to accelerate the computations. Both methods require a computational effort similar to the DAMAS2 algorithm. All three algorithms use an approximate shift invariant point-spread function. %do not take the variation of the %point-spread function into account. %They solve the deconvolution problem only approximately. Furthermore it is described how the DAMAS2 and the Fourier-based NNLS algorithms can be embedded in an outer iteration loop to take the variation of the point-spread function into account. The resulting methods have two nested iterations, which require much more numerical effort than a single DAMAS2 iteration loop. All methods are tested with synthetic data. At first an example with a simple linear array and a small opening angle is considered, where the variation of the point-spread function in the source region is negligible. In this test case the results of the DAMAS2, the modified gradient-type NNLS, and the Richardson-Lucy algorithm are compared. It is shown that these algorithms more or less introduce oscillations in the reconstructed source distribution. A second test case with a planar array and a large opening angle is presented, to demonstrate the influence of a strong variation of the point-spread function. It is shown that the approximate methods lead to distorted results, while the methods with nested iterations give a significantly better reconstruction of the source distribution.

GRB 050822: detailed analysis of an XRF observed bySwift

We report on the temporal and spectral characteristics of the early X-ray emission from the GRB 050822 as observed by Swift. This burst is likely to be an XRF showing major X-ray flares in its XRT light-curve. The quality of the data allows a detailed spectral analysis of the early afterglow in the X-ray band. During the X-ray flares, a positive correlation between the count rate and the spectral hardness (i.e. the higher the count rate, the harder the spectrum) is clearly seen for the X-ray flares. This behaviour, similar to that seen for Gamma-ray pulses, indicates that the energy peak of the spectrum is in the XRT energy band and it moves towards lower energies with time. We show evidence for the possible detection of the emergence of the forward-shock emission, produced at a radius larger than 4 1016 cm in the case of a CBM afterglow model (a formation region clearly different from that producing the prompt emission). Finally, we show that the null detection of a jet break up to T0+4 106 s in the X-ray light curve of this XRF can be understood: i) if the jet seen on-axis is uniform with a large opening angle (); or ii) if the jet is a structured Gaussian-like jet with the line-of-sight outside the bright Gaussian core.

Simulation and laboratory validation of magnetic nozzle effects for the high power helicon thruster

The efficiency of a plasma thruster can be improved if the plasma stream can be highly focused, so that there is maximum conversion of thermal energy to the directed energy. Such focusing can be potentially achieved through the use of magnetic nozzles, but this introduces the potential problem of detachment of plasma from the magnetic field lines tied to the nozzles. Simulations and laboratory testing are used to investigate these processes for the high power helicon (HPH) thruster, which has the capacity of producing a dense (1018−1020m−3) energetic (tens of eV) plasma stream which can be both supersonic and super-Alfvénic within a few antenna wavelengths. In its standard configuration, the plasma plume generated by this device has a large opening angle, due to relatively high thermal velocity and rapid divergence of the magnetic field. With the addition of a magnetic nozzle system, the plasma can be directed/collimated close to the pole of the nozzle system causing an increase in the axial velocity of the plasma, as well as an increase in the Alfvén Mach number. As such the magnetic field of the nozzle is insufficient to pull the plasma back to the spacecraft, i.e., plasma attachment is not a problem for the system. Laboratory results show that the specific impulse (Isp) of the system can be increased by ∼30% by the addition of the nozzle due to the conversion of thermal energy into directed energy in association with a highly collimated profile. An interesting feature of the system is that self-collimation of the beam is expected to occur during continuous operation through plasma currents induced downstream from the magnetic nozzle. These currents lead to magnetic fields that have a smaller divergence than the original vacuum magnetic field so that the following plasma will be more collimated than the proceeding plasma. This self-focusing can lead to beam propagation over extended distances.

High‐Frequency VLBI Imaging of the Jet Base of M87

VLBA and Global VLBI observations of M87 at 43 GHz, some new and some previously published, are used to study the structural evolution of the jet with a spatial resolution of under 100 Schwarzschild radii. The images, taken between 1999 and 2004, have an angular resolution of 0.00043" x 0.00021". An edge-brightened jet structure and an indication of a large opening angle at the jet base are seen in all five epochs. In addition, a probable counter-jet is seen in the latter three epochs. A 22 GHz VLBA image also confirms many of the structures seen at the higher frequency, including the counter-jet. A comparison of the counter-jet flux density at 22 and 43 GHz reveals that it is not free-free absorbed at these frequencies. Attempts to obtain speeds from the proper motions of jet and counter-jet components indicate that these observations are undersampled. The closest pair of images gives apparent speeds of 0.25 to 0.40c for the jet and 0.17c for the counter-jet. These speeds should be treated as lower limits because of possible errors in associating components between epochs. If they are real, they indicate that the jet is oriented 30-45 degrees from the line-of-sight and that the component speeds along the jet are 0.3-0.5c. Using the jet orientation derived from proper motions, the spectral index of the the counter-jet, and a jet-to-counter-jet brightness ratio of 14.4, the inferred bulk flow is 0.6-0.7c, which, given the considerable uncertainties in how to measure the brightness ratio, is not significantly larger than the component speed.