Using Regression Discontinuity Design to Identify the Effect of Zoning

We test the effect of minimum lot zoning on rural-to-urban land use conversion using Regression Discontinuity Design (RDD), a technique that exploits natural discontinuities in the data to identify causal effects. Observations are drawn from either size of a discontinuous minimum lot size zoning boundary. Using these selected sub-samples, a binary discrete choice model of residential land use change is estimated using parcel-level data and other spatially explicit data from an exurban county that lies on the fringes of Cleveland, Ohio. Results show that controlling for unobserved correlation in the data clearly identifies a negative and significant effect of larger minimum lot size zoning on the probability of conversion to a residential use.Land Economics/Use,

THE VALUE OF CLEAN DAIRY AIR: ACCOUNTING FOR ENDOGENEITY AND SPATIALLY CORRELATED ERRORS IN A HEDONIC ANALYSES OF THE IMPACT OF ANIMAL OPERATIONS ON LOCAL PROPERTY VALUES

We study the effect of livestock operations on property values using a hedonic analysis in five Ohio townships. Unlike previous studies, we account for endogenous livestock location variables and spatially correlated errors. Results suggest failure to correct for these problems results in biased estimates of livestock impacts on property values.Land Economics/Use,

THE EFFECTS OF FARMLAND, FARMLAND PRESERVATION AND OTHER NEIGHBORHOOD AMENITIES ON PROXIMATE HOUSING VALUES: RESULTS OF A CONJOINT ANALYSIS OF HOUSING CHOICE

Using stated-preference data from a choice-based conjoint analysis instrument, we estimate willingness to pay for the presence of neighboring land that is dedicated to agricultural use (versus a developed land use) and for the preservation of surrounding farmland as permanent cropland. The data also elucidate how individuals balance the values associated with nearby agricultural land patterns with other key neighborhood characteristics such as neighborhood parks, housing density, commute times, school quality and neighborhood safety. The median respondent from a randomly chosen sample of Columbus, Ohio homeowners was willing to pay $843 annually to avoid immediate conversion of 10 percent of agricultural land within one mile of the house valued in the conjoint experiment while the same respondent was willing to pay$277 annually to preserve the same amount of farmland as permanent cropland. We find provision of neighborhood parks within housing developments to be a strong substitute for farmland preservation.Land Economics/Use,

The mass content of the Sculptor dwarf spheroidal galaxy

We present a new determination of the mass content of the Sculptor dwarf spheroidal galaxy, based on a novel approach which takes into account the two distinct stellar populations present in this galaxy. This method helps to partially break the well-known mass-anisotropy degeneracy present in the modelling of pressure-supported stellar systems.Comment: 6 pages, 3 figures. To appear in the proceedings of IAU Symposium 254 "The Galaxy disk in a cosmological context", Copenhagen, June 200

Simultaneous Multiwavelength Observations of Magnetic Activity in Ultracool Dwarfs. IV. The Active, Young Binary NLTT 33370 AB (=2MASS J13142039+1320011)

We present multi-epoch simultaneous radio, optical, H{\alpha}, UV, and X-ray observations of the active, young, low-mass binary NLTT 33370 AB (blended spectral type M7e). This system is remarkable for its extreme levels of magnetic activity: it is the most radio-luminous ultracool dwarf (UCD) known, and here we show that it is also one of the most X-ray luminous UCDs known. We detect the system in all bands and find a complex phenomenology of both flaring and periodic variability. Analysis of the optical light curve reveals the simultaneous presence of two periodicities, 3.7859 $\pm$ 0.0001 and 3.7130 $\pm$ 0.0002 hr. While these differ by only ~2%, studies of differential rotation in the UCD regime suggest that it cannot be responsible for the two signals. The system's radio emission consists of at least three components: rapid 100% polarized flares, bright emission modulating periodically in phase with the optical emission, and an additional periodic component that appears only in the 2013 observational campaign. We interpret the last of these as a gyrosynchrotron feature associated with large-scale magnetic fields and a cool, equatorial plasma torus. However, the persistent rapid flares at all rotational phases imply that small-scale magnetic loops are also present and reconnect nearly continuously. We present an SED of the blended system spanning more than 9 orders of magnitude in wavelength. The significant magnetism present in NLTT 33370 AB will affect its fundamental parameters, with the components' radii and temperatures potentially altered by ~+20% and ~-10%, respectively. Finally, we suggest spatially resolved observations that could clarify many aspects of this system's nature.Comment: emulateapj, 22 pages, 15 figures, ApJ in press; v2: fixes low-impact error in Figure 15; v3: now in-pres

Optimization of MLS receivers for multipath environments

A receiver is designed for aircraft (A/C), which, as a component of the proposed Microwave Landing System (MLS), is capable of optimal performance in the multipath environments found in air terminal areas. Topics discussed include: the angle-tracking problem of the MLS receiver; signal modeling; preliminary approaches to optimal design; suboptimal design; and simulation study

The Kinematics of the Ultra-Faint Milky Way Satellites: Solving the Missing Satellite Problem

We present Keck/DEIMOS spectroscopy of stars in 8 of the newly discovered ultra-faint dwarf galaxies around the Milky Way. We measure the velocity dispersions of Canes Venatici I and II, Ursa Major I and II, Coma Berenices, Hercules, Leo IV and Leo T from the velocities of 18 - 214 stars in each galaxy and find dispersions ranging from 3.3 to 7.6 km/s. The 6 galaxies with absolute magnitudes M_V < -4 are highly dark matter-dominated, with mass-to-light ratios approaching 1000. The measured velocity dispersions are inversely correlated with their luminosities, indicating that a minimum mass for luminous galactic systems may not yet have been reached. We also measure the metallicities of the observed stars and find that the 6 brightest of the ultra-faint dwarfs extend the luminosity-metallicity relationship followed by brighter dwarfs by 2 orders of magnitude in luminosity; several of these objects have mean metallicities as low as [Fe/H] = -2.3 and therefore represent some of the most metal-poor known stellar systems. We detect metallicity spreads of up to 0.5 dex in several objects, suggesting multiple star formation epochs. Having established the masses of the ultra-faint dwarfs, we re-examine the missing satellite problem. After correcting for the sky coverage of the SDSS, we find that the ultra-faint dwarfs substantially alleviate the discrepancy between the predicted and observed numbers of satellites around the Milky Way, but there are still a factor of ~4 too few dwarf galaxies over a significant range of masses. We show that if galaxy formation in low-mass dark matter halos is strongly suppressed after reionization, the simulated circular velocity function of CDM subhalos can be brought into approximate agreement with the observed circular velocity function of Milky Way satellite galaxies. [slightly abridged]Comment: 22 pages, 15 figures (12 in color), 6 tables, minor revisions in response to referee report. Accepted for publication in Ap

Carbon and nitrogen abundances of individual stars in the Sculptor dwarf spheroidal galaxy

We present [C/Fe] and [N/Fe] abundance ratios and CH({\lambda}4300) and S({\lambda}3883) index measurements for 94 red giant branch (RGB) stars in the Sculptor dwarf spheroidal galaxy from VLT/VIMOS MOS observations at a resolving power R= 1150 at 4020 {\AA}. This is the first time that [N/Fe] abundances are derived for a large number of stars in a dwarf spheroidal. We found a trend for the [C/Fe] abundance to decrease with increasing luminosity on the RGB across the whole metallicity range, a phenomenon observed in both field and globular cluster giants, which can be interpreted in the framework of evolutionary mixing of partially processed CNO material. Both our measurements of [C/Fe] and [N/Fe] are in good agreement with the theoretical predictions for stars at similar luminosity and metallicity. We detected a dispersion in the carbon abundance at a given [Fe/H], which cannot be ascribed to measurement uncertainties alone. We interpret this observational evidence as the result of the contribution of different nucleosynthesis sources over time to a not well-mixed interstellar medium. We report the discovery of two new carbon-enhanced, metal-poor stars. These are likely the result of pollution from material enriched by asymptotic giant branch stars, as indicated by our estimates of [Ba/Fe]> +1. We also attempted a search for dissolved globular clusters in the field of the galaxy by looking for the distinctive C-N pattern of second population globular clusters stars in a previously detected, very metal-poor, chemodynamical substructure. We do not detect chemical anomalies among this group of stars. However, small number statistics and limited spatial coverage do not allow us to exclude the hypotheses that this substructure forms part of a tidally shredded globular cluster.Comment: 18 pages, 14 figures, 3 tables. Accepted to A&

Enhancing the Performance of the T-Peel Test for Thin and Flexible Adhered Laminates

Symmetrically bonded thin and flexible T-peel specimens, when tested on vertical travel machines, can be subject to significant gravitational loading; with the associated asymmetry and mixed-mode failure during peeling. This can cause erroneously high experimental peel forces to be recorded which leads to uncertainty in estimating interfacial fracture toughness and failure mode. To overcome these issues, a mechanical test fixture has been designed for use with vertical test machines, that supports the unpeeled portion of the test specimen and suppresses parasitic loads due to gravity from affecting the peel test. The mechanism, driven by the test machine cross-head, moves at one-half of the velocity of the cross-head such that the unpeeled portion always lies in the plane of the instantaneous center of motion. Several specimens such as bonded polymeric films, laminates, and commercial tapes were tested with and without the fixture, and the importance of the proposed T-peel procedure has been demonstrated