Amenities and the labor earnings function

I was unable to copy/paste the abstract, but the paper argues that amenities exert an important effect on wage differentials over space. Indeed, we show that as much has half of the apparent effect of unionization on wages is actually compensation for less desirable climate in locations that are most unionized.amenities; climate; weather; wage compensation; return to unionization

Sub-picosecond compression by velocity bunching in a photo-injector

We present an experimental evidence of a bunch compression scheme that uses a traveling wave accelerating structure as a compressor. The bunch length issued from a laser-driven radio-frequency electron source was compressed by a factor >3 using an S-band traveling wave structure located immediately downstream from the electron source. Experimental data are found to be in good agreement with particle tracking simulations.Comment: 19 pages, 9 figures, submitted to Phys. Rev. Spec. Topics A&

Mathematical model for the simulation of Dynamic Docking Test System (DDST) active table motion

The mathematical model developed to describe the three-dimensional motion of the dynamic docking test system active table is described. The active table is modeled as a rigid body supported by six flexible hydraulic actuators which produce the commanded table motions

Millisecond accuracy video display using OpenGL under Linux

To measure people’s reaction times to the nearest millisecond, it is necessary to know exactly when a stimulus is displayed. This article describes how to display stimuli with millisecond accuracy on a normal CRT monitor, using a PC running Linux. A simple C program is presented to illustrate how this may be done within X Windows using the OpenGL rendering system. A test of this system is reported that demonstrates that stimuli may be consistently displayed with millisecond accuracy. An algorithm is presented that allows the exact time of stimulus presentation to be deduced, even if there are relatively large errors in measuring the display time

Elk Near Fossil Butte National Monument in Southwest Wyoming Migrate Early to Escape Human Disturbance

Migration allows individuals to strike a balance between risk and reward, and use resources in the places and at times that maximize fitness. Large ungulates commonly migrate to increase access to quality forage in spring and decrease risks associated with winter weather in the fall in an effort to maintain the body condition necessary for winter survival and successful reproduction. However, foraging exists within a realm of strategies employed to maximize fitness, and so animals must take factors like safety into account when choosing to migrate. Here, we use 5 years of data from 73 female elk (Cervus canadensis), most of which are part of a subgroup of elk that utilize a protected area during hunting season, to identify the driving factors behind the initiation of migration from their late summer range. The onset of archery season, remotely sensed vegetation degradation, and having access to lands where hunting was prohibited (Fossil Butte National Monument) initiated autumn migration, with bad weather having a smaller effect. 67% of elk using the Monument initiated migration prior to the onset of archery hunting season (1 September), preemptively avoiding risk, while no elk from the subgroup not using the Monument left prior to archery season, despite spending summer at higher elevations. Departure from productive summer range nearly two months before vegetation senescence afforded protection on the Monument during hunting season, but decreased access to late summer-fall forage (integrated NDVI) by 21%. Our results illustrate the complexity of managing a wide-ranging ungulate across jurisdictions with multiple missions

Ages and Abundances of Red Sequence Galaxies as a Function of LINER Emission Line Strength

Although the spectrum of a prototypical early-type galaxy is assumed to lack emission lines, a substantial fraction (likely as high as 30%) of nearby red sequence galaxy spectra contain emission lines with line ratios characteristic of low ionization nuclear emission-line regions (LINERs). We use spectra of ~6000 galaxies from the Sloan Digital Sky Survey (SDSS) in a narrow redshift slice (0.06 < z < 0.08) to compare the stellar populations of red sequence galaxies with and without LINER-like emission. The spectra are binned by internal velocity dispersion and by emission properties to produce high S/N stacked spectra. The recent stellar population models of R. Schiavon (2007) make it possible to measure ages, [Fe/H], and individual elemental abundance ratios [Mg/Fe], [C/Fe], [N/Fe], and [Ca/Fe] for each of the stacked spectra. We find that red sequence galaxies with strong LINER-like emission are systematically 2-3.5 Gyr (10-40%) younger than their emission-free counterparts at the same velocity dispersion. This suggests a connection between the mechanism powering the emission (whether AGN, post-AGB stars, shocks, or cooling flows) and more recent star formation in the galaxy. We find that mean stellar age and [Fe/H] increase with velocity dispersion for all galaxies. Elemental abundance [Mg/Fe] increases modestly with velocity dispersion in agreement with previous results, and [C/Fe] and [N/Fe] increase more strongly with velocity dispersion than does [Mg/Fe]. [Ca/Fe] appears to be roughly solar for all galaxies. At fixed velocity dispersion, galaxies with fainter r-band luminosities have lower [Fe/H] and older ages but similar abundance ratios compared to brighter galaxies.Comment: 25 pages, 17 figures, Accepted for publication in ApJ as of 16 July 2007; acceptance status updated, paper unchange