Modeling and Managing Urban Growth at the Rural-Urban Fringe: A Parcel-Level Model of Residential Land Use Change

As many local and state governments in the United States grapple with increasing growth pressures, the need to understand the economic and institutional factors underlying these pressures has taken on added urgency. From an economic perspective, individual land use decisions play a central role in the manifestation of growth pressures, as changes in land use pattern are the cumulative result of numerous individual decisions regarding the use of lands. In this study, the issue of growth management is addressed by developing a spatially disaggregated, microeconomic model of land conversion decisions suitable for describing residential land use change at the rural-urban fringe. The model employs parcel-level data on land use in Calvert County, Maryland, a rapidly growing rural-urban fringe county. A probabilistic model of residential land use change is estimated using a duration model, and the parameter estimates are employed to simulate possible future growth scenarios under alternative growth management scenarios. Results suggest that "smart growth" objectives are best met when policies aimed at concentrating growth in target areas are implemented in tandem with policies designed to preserve rural or open space lands.Land Economics/Use,

VALIDITY OF STRIDE LENGTH ESTIMATES OBTAINED FROM OPTOJUMP

The purpose of the present study was to ascertain the validity of stride length estimates obtained from OptoJump (Microgate, Bolzano, Italy) using displacement data derived from three-dimensional videography as criterion. One subject repeatedly ran through a 4 m section of OptoJump to obtain real-time stride length estimates. Corresponding criterion stride length estimates were also obtained from the displacement data derived from video. 95% limits of agreement were applied to the 56 pairs of measurements revealing an error interval of 4.2 ± 23.1 mm. We concluded that stride length estimates obtained from OptoJump lacked sufficient validity for use in motor control studies. However, the capability of this system to acquire other relevant data in real-time, provides sufficient scope to suggest pursuing the development of this system

Radiative transfer modelling for the NOMAD-UVIS instrument on the ExoMars Trace Gas Orbiter mission

The NOMAD (Nadir and Occultation for MArs Discovery) instrument is a 3-channel (2 IR, 1 UV/Vis) spectrometer due to fly on the 2016 ExoMars Trace Gas Orbiter mission. A radiative transfer model for Mars has been developed providing synthetic spectra to simulate observations of the UVIS channel in both solar occultation and nadir viewing geometries. This will allow for the characterization and mitigation of the influence of dust on retrievals of ozone abundance

LRG-BEASTS III: Ground-based transmission spectrum of the gas giant orbiting the cool dwarf WASP-80

We have performed ground-based transmission spectroscopy of the hot Jupiter orbiting the cool dwarf WASP-80 using the ACAM instrument on the William Herschel Telescope (WHT) as part of the LRG-BEASTS programme. This is the third paper of a ground-based transmission spectroscopy survey of hot Jupiters using low-resolution grism spectrographs. We observed two transits of the planet and have constructed transmission spectra spanning a wavelength range of 4640-8840A. Our transmission spectrum is inconsistent with a previously claimed detection of potassium in WASP-80b's atmosphere, and is instead most consistent with a haze. We also do not see evidence for sodium absorption at a resolution of 100A.Comment: 11 pages, 9 figures. Accepted for publication in MNRA

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

High power operation of an X-band gyrotwistron

We report the first experimental verification of a gyrotwistron amplifier. The device utilized a single 9.858 GHz, TE011 cavity, a heavily attenuated drift tube, and a long tapered output waveguide section. With a 440 kV, 200-245 A, 1 μs electron beam and a sharply tapered axial magnetic field, peak powers above 21 MW were achieved with a gain near 24 dB. Performance was limited by competition from a fundamental TE11 mode. A multimode code was developed to analyze this system, and simulations were in good agreement with the experiment

The optical transmission spectrum of the hot Jupiter HAT-P-32b: clouds explain the absence of broad spectral features?

We report Gemini-North GMOS observations of the inflated hot Jupiter HAT-P-32b during two primary transits. We simultaneously observed two comparison stars and used differential spectro-photometry to produce multi-wavelength light curves. 'White' light curves and 29 'spectral' light curves were extracted for each transit and analysed to refine the system parameters and produce transmission spectra from 520-930nm in ~14nm bins. The light curves contain time-varying white noise as well as time-correlated noise, and we used a Gaussian process model to fit this complex noise model. Common mode corrections derived from the white light curve fits were applied to the spectral light curves which significantly improved our precision, reaching typical uncertainties in the transit depth of ~2x10^-4, corresponding to about half a pressure scale height. The low resolution transmission spectra are consistent with a featureless model, and we can confidently rule out broad features larger than about one scale height. The absence of Na/K wings or prominent TiO/VO features is most easily explained by grey absorption from clouds in the upper atmosphere, masking the spectral features. However, we cannot confidently rule out clear atmosphere models with low abundances (~10^-3 solar) of TiO, VO or even metal hydrides masking the Na and K wings. A smaller scale height or ionisation could also contribute to muted spectral features, but alone are unable to to account for the absence of features reported here.Comment: 17 pages, 11 figures, 2 tables, accepted for publication in MNRA

A Gemini ground-based transmission spectrum of WASP-29b: a featureless spectrum from 515 to 720nm

We report Gemini-South GMOS observations of the exoplanet system WASP-29 during primary transit as a test case for differential spectrophotometry. We use the multi-object spectrograph to observe the target star and a comparison star simultaneously to produce multiple light curves at varying wavelengths. The 'white' light curve and fifteen 'spectral' light curves are analysed to refine the system parameters and produce a transmission spectrum from 515 to 720nm. All light curves exhibit time-correlated noise, which we model using a variety of techniques. These include a simple noise rescaling, a Gaussian process model, and a wavelet based method. These methods all produce consistent results, although with different uncertainties. The precision of the transmission spectrum is improved by subtracting a common signal from all the spectral light curves, reaching a typical precision of ~1x10^-4 in transit depth. The transmission spectrum is free of spectral features, and given the non-detection of a pressure broadened Na feature, we can rule out the presence of a Na rich atmosphere free of clouds or hazes, although we cannot rule out a narrow Na core. This indicates that Na is not present in the atmosphere, and/or that clouds/hazes play a significant role in the atmosphere and mask the broad wings of the Na feature, although the former is a more likely explanation given WASP-29b's equilibrium temperature of ~970 K, at which Na can form various compounds. We also briefly discuss the use of Gaussian process and wavelet methods to account for time correlated noise in transit light curves.Comment: 15 pages, 9 figures, 3 tables. Published in MNRAS. Figure 2 corrected in version