The European Large Area ISO Survey - ISOPHOT results using the MPIA-pipeline

The European Large Area ISO Survey (ELAIS) will provide Infrared observations of 4 regions in the sky with ISO. Around 2000 Infrared sources have been detected at 7 and 15 microns (with ISOCAM), 90 and 175 microns (with ISOPHOT)) over 13 square degrees of the sky. We present the source extraction pipeline of the 90 microns ISOPHOT observations, describe and discuss the results obtained and derive the limits of the ELAIS observational strategy.Comment: 4 pages, 5 figures, to appear in the ISO conference "The Universe as seen by ISO", 1998, UNESCO, Pari

Getting a Second Wind: Reviving Natural Rights Clauses as a Means to Challenge Unjustified Occupational Licensing Regulations

Occupational licensing refers to a government-imposed regulation which requires an individual to obtain a license before engaging in a certain line of work. Over the last several decades, occupational licensing regulations have expanded rapidly. While some of these regulations can be justified as a form of consumer protection (as in the medical industry), many simply operate as barriers to entry (as in the interior design industry). Furthermore, these regulations impose economic costs that fall disproportionately on those who are economically disadvantaged. Fortunately, bipartisan state legislative efforts have begun to make some progress in rolling back these regulations. However, because legislative reform is often slow, the bearers of these burdensome regulations often seek redress through the court systems. In a recent case, Ladd v. Real Estate Commission,1 the Pennsylvania Supreme Court ruled that certain licensing requirements violated the right to pursue one’s chosen occupation—a right it said was protected by the state’s natural rights clause enshrined in the Pennsylvania Constitution. We believe that Ladd’s conclusion is correct in light of the historical understanding of these natural rights clauses. Importantly, Pennsylvania is one of thirty-three states to have such a clause in its state constitution. These natural rights clauses provide an easy anchor point by which to argue that unjustified occupational licensing unduly interferes with one’s right to pursue a chosen occupation and, consequently, interferes with the rights guaranteed by the state constitution. Therefore, Ladd can serve as a powerful example of how to limit the breadth of occupational licensing through state court litigation in the majority of states

Modelling photometric reverberation data -- a disk-like broad-line region and a potentially larger black hole mass for 3C120

We consider photometric reverberation mapping, where the nuclear continuum variations are monitored via a broad-band filter and the echo of emission line clouds of the broad line region (BLR) is measured with a suitable narrow-band (NB) filter. We investigate how an incomplete emission-line coverage by the NB filter influences the BLR size determination. This includes two basic cases: 1) a symmetric cut of the blue and red part of the line wings, and 2) the filter positioned asymmetrically to the line centre so that essentially a complete half of the emission line is contained in the NB filter. Under the assumption that the BLR size is dominated by circular Keplerian orbits, we find that symmetric cutting of line wings may lead to overestimating the BLR size by less than 5%. The case of asymmetric half-line coverage, similar as for our data of the Seyfert 1 galaxy 3C120, yields the BLR size with a bias of less than 1%. Our results suggest that any BLR size bias due to narrow-band line cut in photometric reverberation mapping is small and in most cases negligible. We used well sampled photometric reverberation mapping light curves with sharp variation features in both the continuum and the Hbeta light curves to determine the geometry type of the Hbeta BLR for 3C120. Modelling of the light curve, under the assumption that the BLR is essentially virialised, argues against a spherical geometry and favours a nearly face-on disk-like geometry with inclination i = 10 +/- 4 deg and extension from 22 to 28 light days. The low inclination may lead to a larger black hole mass than the derived when using the average geometry scaling factor f=5.5. We discuss deviations of Seyfert 1 galaxies from the M_BH - sigma relation.Comment: 9 pages, 11 figures, accepted for publication in Astronomy and Astrophysic

High accuracy measure of atomic polarizability in an optical lattice clock

Despite being a canonical example of quantum mechanical perturbation theory, as well as one of the earliest observed spectroscopic shifts, the Stark effect contributes the largest source of uncertainty in a modern optical atomic clock through blackbody radiation. By employing an ultracold, trapped atomic ensemble and high stability optical clock, we characterize the quadratic Stark effect with unprecedented precision. We report the ytterbium optical clock's sensitivity to electric fields (such as blackbody radiation) as the differential static polarizability of the ground and excited clock levels: 36.2612(7) kHz (kV/cm)^{-2}. The clock's fractional uncertainty due to room temperature blackbody radiation is reduced an order of magnitude to 3 \times 10^{-17}.Comment: 5 pages, 3 figures, 2 table

Carbon footprints for wheat cropping systems in semiarid prairies

Non-Peer ReviewedWheat is the world's most favored cereal food source, second to rice. However, the production of wheat crop is often considered to be environmentally-unfriendly, because of the large inputs of fuel, inorganic fertilizer, and pesticides, and these inputs are known to be a major source of greenhouse gases that contribute negatively to climate change. We do not know whether adopting new and improved farming practices for wheat production can increase crop productivity while concurrently reducing overall carbon emissions. In this study, we quantified the carbon footprint of alternative wheat production systems suited to the semiarid Canadian prairie. Data from a 25-year (1985-2009) field experiment conducted in southwestern Saskatchewan were analyzed. We found that wheat that was fertilized with 20 to 48 kg N ha-1 (based on soil tests) produced grain yields of 980 to 2460 kg N ha-1 annually (depending upon weather conditions). Wheat produced with improved farming practices had a negative (or favorable) carbon footprint, averaging -256 kg CO2 equivalents ha-1 or -0.146 kg CO2 equivalents kg-1 of grain yield. Wheat produced in a lentil-wheat rotation had the highest carbon footprint value at -0.370 kg CO2 equivalents per kg of grain yield. On average, for each kg of wheat grain produced a net 0.018 to 0.370 kg CO2 equivalent was sequestrated from the atmosphere into the soil. Our study show that with improved farming practices wheat crops grown on the semiarid Canadian prairie can convert more CO2 from the atmosphere than is actually emitted during its production