Absolute Calibration of the Radio Astronomy Flux Density Scale at 22 to 43 GHz Using Planck

The Planck mission detected thousands of extragalactic radio sources at frequencies from 28 to 857 GHz. Planck's calibration is absolute (in the sense that it is based on the satellite's annual motion around the Sun and the temperature of the cosmic microwave background), and its beams are well characterized at sub-percent levels. Thus Planck's flux density measurements of compact sources are absolute in the same sense. We have made coordinated VLA and ATCA observations of 65 strong, unresolved Planck sources in order to transfer Planck's calibration to ground-based instruments at 22, 28, and 43 GHz. The results are compared to microwave flux density scales currently based on planetary observations. Despite the scatter introduced by the variability of many of the sources, the flux density scales are determined to 1-2% accuracy. At 28 GHz, the flux density scale used by the VLA runs 3.6% +- 1.0% below Planck values; at 43 GHz, the discrepancy increases to 6.2% +- 1.4% for both ATCA and the VLA.Comment: 16 pages, 4 figures and 4 table

Too Tired to Think Outside the Box? An Analysis of Ego Depletion\u27s Effects on Creativity

Recent research suggests that complex tasks that require self-control to complete, such as strenuous tests or complicated decisions, put a strain on the limited resource known as the ego. The ego is thought to be a kind of mental energy reserve that can be depleted with use. Previous studies have shown that, not only is it possible to deplete the ego, but this depletion leads to poor performance on various later tasks involving skills such as decision making, cognitive extrapolation, reasoning, and self-control. Two models in particular have gained support recently: the resource model –involving blood glucose– and the trade-off model – involving distribution of attention. Because both creativity and the ego are thought to be biologically based and because cognitive flexibility, which has been shown to be highly correlated with creativity, seems to require a fairly high level of processing like other processes on which ego depletion has been shown to have a negative effect, it is reasonable to suggest that ego depletion would cause a decrease in creativity as well

Behavior of estimates of the mean life of a radioactive source

This thesis presents the results of sampling experiments investigating the properties of estimates of the mean life of a radioactive source in the presence of a constant unknown background. An iterative estimation procedure is used where the estimates are maximum liklihood estimates with asymptotic variances. The estimation procedure was programmed in FORTRAN for the I.B.M. 1620 computer and a large number of examples were run to study the bias, divergence and variance of the estimates. Particular emphasis is placed upon the reduction in the number of divergent cases by improvements in the estimation procedure

A time series of hydroxylamine (NH2OH) in the southwestern Baltic Sea

Hydroxylamine (NH(2)OH) is an intermediate of the marine nitrogen cycle and in marine environments dissolved NH(2)OH is short-lived. In order to investigate the distribution of NH(2)OH under varying oxygen conditions, its seasonal variability was investigated on a monthly basis from July 2005 to May 2006 at the time series station Boknis Eck located in the Eckernforde Bay (southwestern Baltic Sea). NH(2)OH concentrations were generally low and close to the detection limit. However, a pronounced increase was observed after the seasonal thermohaline stratification period with low oxygen/anoxic conditions in the deep layers was terminated in November 2005. The increase of NH(2)OH was associated with the re-oxygenation of the water column. We conclude that NH(2)OH was produced in-situ during nitrification. We suggest that the detection of significant amounts of NH(2)OH can be used as an indicator for a "fresh" nitrifying system

Book Reviews

Reviews of the following books: Bootleggers, Lobstermen & Lumberjacks: Fifty of the Grittiest Moments in the History of Harscrabble New England by Matthew P. Mayo; Remarkable Americans: The Washburn Family by Kerck Kelsey; Historic Photos of Maine by Francis Pollitt; On Pownal Time: One Hundred Years in a Rural Maine Town by Donna Fulton Boyles, James G. Boyles, Craig Dietrich, Sherilyn R. Dietrich, Jennifer Blackstone Kaplan and Joseph R. Raymond; Frontier to Industrial City: Lewiston Town Politics, 1768-1863 by Douglas I. Hodgkin; In the Shadow of the Eagle by Donna Loring; The Land In Between: the Upper St. John Valley from Prehistory to World War One by Beatrice Craig & Maxime Dagenais with the collaboration of Lisa Ornstein and Guy Dubay; Maine in the World: Stories of Some of Those from Here Who Went Away by Neil Rolde

The Grizzly, October 12, 1984

Students and Administrators Disagree on Effectiveness of Existing Alcohol Policies • Former Economics Chairman Now ACE Fellow • Twisted Sister and the State of Modern Youth Dissidence • News of Yesteryear: War Brings Feminine Touch to Freeland Hall • UC Welcomes Three Foreign Students • Gridders Handle Hopkins • Off-Campus Entertainment: Pulsations! • Shorts: Ferguson Concert; Thurber Carnival; Trivia-thon Scheduled • New Faculty: Math Welcomes Shaw • Some Keystone Factshttps://digitalcommons.ursinus.edu/grizzlynews/1124/thumbnail.jp

An Independent and Coordinated Criterion for Kinematic Aircraft Maneuvers

This paper proposes a mathematical definition of an aircraft-separation criterion for kinematic-based horizontal maneuvers. It has been formally proved that kinematic maneu- vers that satisfy the new criterion are independent and coordinated for repulsiveness, i.e., the distance at closest point of approach increases whether one or both aircraft maneuver according to the criterion. The proposed criterion is currently used in NASA's Airborne Coordinated Resolution and Detection (ACCoRD) set of tools for the design and analysis of separation assurance systems

Continuous trench, pulsed laser ablation for micro-machining applications

The generation of controlled 3D micro-features by pulsed laser ablation in various materials requires an understanding of the material's temporal and energetic response to the laser beam. The key enabler of pulsed laser ablation for micro-machining is the prediction of the removal rate of the target material, thus allowing real-life machining to be simulated mathematically. Usually, the modelling of micro-machining by pulsed laser ablation is done using a pulse-by-pulse evaluation of the surface modification, which could lead to inaccuracies when pulses overlap. To address these issues, a novel continuous evaluation of the surface modification that use trenches as a basic feature is presented in this paper. The work investigates the accuracy of this innovative continuous modelling framework for micro-machining tasks on several materials. The model is calibrated using a very limited number of trenches produced for a range of powers and feed speeds; it is then able to predict the change in topography with a size comparable to the laser beam spot that arises from essentially arbitrary toolpaths. The validity of the model has been proven by being able to predict the surface obtained from single trenches with constant feed speed, single trenches with variable feed speed and overlapped trenches with constant feed speed for three different materials (graphite, polycrystalline diamond and a metal-matrix diamond CMX850) with low error. For the three materials tested, it is found that the average error in the model prediction for a single trench at constant feed speed is lower than 5 % and for overlapped trenches the error is always lower than 10 %. This innovative modelling framework opens avenues to: (i) generate in a repeatable and predictable manner any desired workpiece microtopography; (ii) understand the pulsed laser ablation machining process, in respect of the geometry of the trench produced, therefore improving the geometry of the resulting parts; (iii) enable numerical optimisation for the beam path, thus supporting the development of accurate and flexible computer assisted machining software for pulsed laser ablation micro-machining applications

GRB060602B = Swift J1749.4-2807: an unusual transiently accreting neutron-star X-ray binary

We present an analysis of the Swift BAT and XRT data of GRB060602B, which is most likely an accreting neutron star in a binary system and not a gamma-ray burst. Our analysis shows that the BAT burst spectrum is consistent with a thermonuclear flash (type-I X-ray burst) from the surface of an accreting neutron star in a binary system. The X-ray binary nature is further confirmed by the report of a detection of a faint point source at the position of the XRT counterpart of the burst in archival XMM-Newton data approximately 6 years before the burst and in more recent XMM-Newton data obtained at the end of September 2006 (nearly 4 months after the burst). Since the source is very likely not a gamma-ray burst, we rename the source Swift J1749.4-2807, based on the Swift/BAT discovery coordinates. Using the BAT data of the type-I X-ray burst we determined that the source is at most at a distance of 6.7+-1.3 kpc. For a transiently accreting X-ray binary its soft X-ray behaviour is atypical: its 2-10 keV X-ray luminosity (as measured using the Swift/XRT data) decreased by nearly 3 orders of magnitude in about 1 day, much faster than what is usually seen for X-ray transients. If the earlier phases of the outburst also evolved this rapidly, then many similar systems might remain undiscovered because the X-rays are difficult to detect and the type-I X-ray bursts might be missed by all sky surveying instruments. This source might be part of a class of very-fast transient low-mass X-ray binary systems of which there may be a significant population in our Galaxy.Comment: Accepted for publication in MNRA