Radial Velocity Confirmation of a Binary Detected from Pulse Timings

A periodic variation in the pulse timings of the pulsating hot subdwarf B star CS 1246 was recently discovered via the O-C diagram and suggests the presence of a binary companion with an orbital period of two weeks. Fits to this phase variation, when interpreted as orbital reflex motion, imply CS 1246 orbits a barycenter 11 light-seconds away with a velocity of 16.6 km/s. Using the Goodman spectrograph on the SOAR telescope, we decided to confirm this hypothesis by obtaining radial velocity measurements of the system over several months. Our spectra reveal a velocity variation with amplitude, period, and phase in accordance with the O-C diagram predictions. This corroboration demonstrates that the rapid pulsations of hot subdwarf B stars can be adequate clocks for the discovery of binary companions via the pulse timing method.Comment: Accepted for publication in ApJ Letters; 5 pages, 2 figures, 3 tables; uses emulateap

Divide and Conquer? The Russian Plan for Ownership of the Caspian Sea

The search for alternative sources of oil has renewed U.S. interest in the Caspian Sea. Bordered by Russia, Azerbaijan, Iran, and the Central Asian states of Kazakhstan and Turkmenistan, the Caspian Sea contains up to thirty-three billion barrels of proven oil reserYes. The legal status of the Caspian has remained unresolved since the collapse of the Soviet Union, however. In the early 1990s Russia joined with Iran to argue for common ownership of the sea by all five states, aiming for Yeto power over Western involvement in the region. Now, Russia argues for dividing the seabed (and the oil and gas underneath it) into national sectors, while leaving most of the surface waters for common management and use. The Russian solution offers political and economic benefits to both Russia and the United States in the short run, but may be an unsound basis for long-term stability in the Caspian region

State Failure and the Use of Force in the Age of Global Terror

The expansion of U.S. counterterrorist operations throughout the world coincides with a growing sense among some U.S. policymakers that so-called failed states pose grave threats to international security. The governments of failed states have weakened to the point that they can no longer provide public goods, such as territorial integrity, economic infrastructure, and physical security. U.S. defense strategists suspect that the lawlessness of failed states may do more to undermine security in the United States than direct confrontation by hostile governments. Denying terrorists the sanctuary they seek in failed states may become a central feature in the war on terror, and it is likely that the United States will use preemptive force against suspected terrorists inside a state that is incapable of policing itself. This Note examines the legality of using preemptive military force against suspected terrorists located in failed states

Blasting Bridges And Culverts: Water Overpressure And Vibration Effects On Fish And Habitat

Thesis (M.S.) University of Alaska Fairbanks, 2009Water overpressures and ground vibrations from blasting may injure or kill salmonid fish in streams and embryos in streambeds. Explosives are used to remove failing structures in remote areas of the Tongass National Forest that impair watershed function. The State of Alaska Department of Fish and Game standards limit blast induced water overpressures to 2.7 lb/in 2 (18.6 kPa) and streambed vibrations to 0.5 in/s (13 mm/s) when embryos are present. Researchers, however, have reported salmonid mortality from pressures only as low as 12.3 and 19.3 lbs/in2 (85 and 133 kPa) and embryo mortality from vibrations as low as 5.75 in/s (146 mm/s). I recorded in-stream overpressures and streambed vibrations with hydrophones and geophones at various distances from log bridge, log culvert, and metal culvert blasts. Peak water pressures (lb/in2) were directly related to cube-root scaled distances with an attenuation rate of -1.51. Peak particle velocities in gravel were directly related to square-root scaled distances (SRSD, ft/lb 1/2) with an attenuation rate of -0.75. Water pressures were less than 7.1 lb/in2 (49.0 kPa) in all but one blast, and streambed vibrations did not exceed 5.5 in/s in gravel streambeds. State standards should be revised to reflect reported mortality and these observations of blasts in streams

An eclipsing post common-envelope system consisting of a pulsating hot subdwarf B star and a brown dwarf companion

Hot subdwarf B stars (sdBs) are evolved, core helium-burning objects located on the extreme horizontal branch. Their formation history is still puzzling as the sdB progenitors must lose nearly all of their hydrogen envelope during the red-giant phase. About half of the known sdBs are in close binaries with periods from 1.2 h to a few days, a fact that implies they experienced a common-envelope phase. Eclipsing hot subdwarf binaries (also called HW Virginis systems) are rare but important objects for determining fundamental stellar parameters. Even more significant and uncommon are those binaries containing a pulsating sdB, as the mass can be determined independently by asteroseismology. Here we present a first analysis of the eclipsing hot subdwarf binary V2008-1753. The light curve shows a total eclipse, a prominent reflection effect, and low--amplitude pulsations with periods from 150 to 180 s. An analysis of the light-- and radial velocity (RV) curves indicates a mass ratio close to $q = 0.146$, an RV semi-amplitude of $K=54.6 \,\rm kms^{-1}$, and an inclination of $i=86.8^\circ$. Combining these results with our spectroscopic determination of the surface gravity, $\log \,g = 5.83$, the best--fitting model yields an sdB mass of 0.47$M_{\rm \odot}$ and a companion mass of $69 M_{\rm Jup}$. As the latter mass is below the hydrogen-burning limit, V2008-1753 represents the first HW Vir system known consisting of a pulsating sdB and a brown dwarf companion. Consequently, it holds great potential for better constraining models of sdB binary evolution and asteroseismology.Comment: 9 pages, 8 figures, accepted for A&

A number or a person?: perspectives on credit scoring and fair mortgage lending: article four in a five-part series

This fourth article in a five-part series on credit scoring showcases three different perspectives. Up for debate is how lenders can ensure fair treatment to all mortgage applicants and how consumers can be educated about the effect their credit score has on loan pricing.Mortgage loans

Stability, reliability and cross-mode correlations of tests in a recommended 8-minute performance assessment battery

A need exists for an automated performance test system to study drugs, agents, treatments, and stresses of interest to the aviation, space, and environmental medical community. The purpose of this present study is to evaluate tests for inclusion in the NASA-sponsored Automated Performance Test System (APTS). Twenty-one subjects were tested over 10 replications with tests previously identified as good candidates for repeated-measure research. The tests were concurrently administered in paper-and-pencil and microcomputer modes. Performance scores for the two modes were compared. Data from trials 1 to 10 were examined for indications of test stability and reliability. Nine of the ten APT system tests achieved stability. Reliabilities were generally high. Cross-correlation of microbased tests with traditional paper-and-pencil versions revealed similarity of content within tests in the different modes, and implied at least three cognition and two motor factors. This protable, inexpensive, rugged, computerized battery of tests is recommended for use in repeated-measures studies of environmental and drug effects on performance. Identification of other tests compatible with microcomputer testing and potentially capable of tapping previously unidentified factors is recommended. Documentation of APTS sensitivity to environmental agents is available for more than a dozen facilities and is reported briefly. Continuation of such validation remains critical in establishing the efficacy of APTS tests

On the role of a new type of correlated disorder in extended electronic states in the Thue-Morse lattice

A new type of correlated disorder is shown to be responsible for the appearance of extended electronic states in one-dimensional aperiodic systems like the Thue-Morse lattice. Our analysis leads to an understanding of the underlying reason for the extended states in this system, for which only numerical evidence is available in the literature so far. The present work also sheds light on the restrictive conditions under which the extended states are supported by this lattice.Comment: 11 pages, LaTeX V2.09, 1 figure (available on request), to appear in Physical Review Letter

Growth and Structure of Stochastic Sequences

We introduce a class of stochastic integer sequences. In these sequences, every element is a sum of two previous elements, at least one of which is chosen randomly. The interplay between randomness and memory underlying these sequences leads to a wide variety of behaviors ranging from stretched exponential to log-normal to algebraic growth. Interestingly, the set of all possible sequence values has an intricate structure.Comment: 4 pages, 4 figure