Tracer of electrical conduit or pipes

Device matches ends of a buried conduit, transversing an inaccessible area, without cutting the current

Can Hiring Quotas Work? The Effect Of The Nitaqat Program On The Saudi Private Sector

This paper studies the effects of quota-based labor regulations on firms in the context of Saudi Arabia\u27s Nitaqat program, which imposed quotas for Saudi hiring at private firms. I use a comprehensive firm-level administrative dataset and exploit kinks in hiring incentives generated by the quotas to estimate the effects of this policy. I find that the program increased native employment at substantial cost to firms, as demonstrated by increasing exit rates and decreasing total employment at surviving firms. Firms without any Saudi employees at the onset of the program appear to bear most of these costs

Identifying Compact Symmetric Objects in the Southern Sky

We present results of multifrequency polarimetric VLBA observations of 20 compact radio sources. The observations represent the northern and southern extensions of a large survey undertaken to identify Compact Symmetric Objects (CSOs) Observed in the Northern Sky (COINS). CSOs are young radio galaxies whose jet axes lie close to the plane of the sky, and whose appearance is therefore not dominated by relativistic beaming effects. The small linear sizes of CSOs make them valuable for studies of both the evolution of radio galaxies and testing unified schemes for active galactic nuclei (AGN). In this paper we report on observations made of 20 new CSO candidates discovered in the northern and southern extremities of the VLBA Calibrator Survey. We identify 4 new CSOs, and discard 12 core-jet sources. The remaining 4 sources remain candidates pending further investigation. We present continuum images at 5 GHz and 15 GHz and, where relevant, images of the polarized flux density and spectral index distributions for the 8 new CSOs and CSO candidates.Comment: accepted to Ap

The COINS Sample - VLBA Identifications of Compact Symmetric Objects

We present results of multifrequency polarimetric VLBA observations of 34 compact radio sources. The observations are part of a large survey undertaken to identify CSOs Observed in the Northern Sky (COINS). Compact Symmetric Objects (CSOs) are of particular interest in the study of the physics and evolution of active galaxies. Based on VLBI continuum surveys of ~2000 compact radio sources, we have defined a sample of 52 CSOs and CSO candidates. In this paper, we identify 18 previously known CSOs, and introduce 33 new CSO candidates. We present continuum images at several frequencies and, where possible, images of the polarized flux density and spectral index distributions for the 33 new candidates and one previously known but unconfirmed source. We find evidence to support the inclusion of 10 of these condidates into the class of CSOs. Thirteen candidates, including the previously unconfirmed source, have been ruled out. Eleven sources require further investigation. The addition of the 10 new confirmed CSOs increases the size of this class of objects by 50%.Comment: 24 pages, incl 8 figures. Accepted for publication in ApJ. Figure quality degraded in the interests of space, full gzipped PS version also available at http://www.ee.nmt.edu/~apeck/papers

Monitoring the Bi-Directional Relativistic Jets of the Radio Galaxy 1946+708

We report on a multi-frequency, multi-epoch campaign of Very Long Baseline Interferometry observations of the radio galaxy 1946+708 using the VLBA and a Global VLBI array. From these high-resolution observations we deduce the kinematic age of the radio source to be $\sim$4000 years, comparable with the ages of other Compact Symmetric Objects (CSOs). Ejections of pairs of jet components appears to take place on time scales of 10 years and these components in the jet travel outward at intrinsic velocities between 0.6 and 0.9 c. From the constraint that jet components cannot have intrinsic velocities faster than light, we derive H_0 > 57 km s^-1 Mpc^-1 from the fastest pair of components launched from the core. We provide strong evidence for the ejection of a new pair of components in ~1997. From the trajectories of the jet components we deduce that the jet is most likely to be helically confined, rather than purely ballistic in nature.Comment: 20 pages, 8 figures, accepted to Ap

Conceptual design for spacelab pool boiling experiment

A pool boiling heat transfer experiment to be incorporated with a larger two-phase flow experiment on Spacelab was designed to confirm (or alter) the results of earth-normal gravity experiments which indicate that the hydrodynamic peak and minimum pool boiling heat fluxes vanish at very low gravity. Twelve small sealed test cells containing water, methanol or Freon 113 and cylindrical heaters of various sizes are to be built. Each cell will be subjected to one or more 45 sec tests in which the surface heat flux on the heaters is increased linearly until the surface temperature reaches a limiting value of 500 C. The entire boiling process will be photographed in slow-motion. Boiling curves will be constructed from thermocouple and electric input data, for comparison with the motion picture records. The conduct of the experiment will require no more than a few hours of operator time