Determining the change in welfare estimates from introducing measurement error in non-linear choice models

Observed and unobserved characteristics of an individual are often used by researchers to explain choices over the provision of environmental goods. One means for identifying what is typically an unobserved characteristic, such as an attitude, is through some data reduction technique, such as factor analysis. However, the resultant variable represents the true attitude with measurement error, and hence, when included into a non-linear choice model, introduces bias in the model. There are well established methods to overcome this issue, which are seldom implemented. In an application to preferences over two water source alternatives for Perth in Western Australia, we use structural equation modeling within a discrete choice model to determine whether welfare measures are significantly impacted by ignoring measurement error in latent attitudes, and the advantage to policy makers from understanding what drives certain attitudes.contingent valuation, attitudes, structural equation modeling, recycled water, Environmental Economics and Policy, Research Methods/ Statistical Methods, Q51, Q53, C13,

From manuscript catalogues to a handbook of Syriac literature: Modeling an infrastructure for Syriaca.org

Despite increasing interest in Syriac studies and growing digital availability of Syriac texts, there is currently no up-to-date infrastructure for discovering, identifying, classifying, and referencing works of Syriac literature. The standard reference work (Baumstark's Geschichte) is over ninety years old, and the perhaps 20,000 Syriac manuscripts extant worldwide can be accessed only through disparate catalogues and databases. The present article proposes a tentative data model for Syriaca.org's New Handbook of Syriac Literature, an open-access digital publication that will serve as both an authority file for Syriac works and a guide to accessing their manuscript representations, editions, and translations. The authors hope that by publishing a draft data model they can receive feedback and incorporate suggestions into the next stage of the project.Comment: Part of special issue: Computer-Aided Processing of Intertextuality in Ancient Languages. 15 pages, 4 figure

Morphology and thermal conductivity of model organic aerogels

The intersection volume of two independent 2-level cut Gaussian random fields is proposed to model the open-cell microstructure of organic aerogels. The experimentally measured X-ray scattering intensity, surface area and solid thermal conductivity of both polymeric and colloidal organic aerogels can be accounted for by the model.Comment: 5 pages. RevTex with 4 encapsulated figures. Higher resolution figures have been submitted for publication. To be published in Phys. Rev. E (Rapid Comm.). email, [email protected]

Unified control/structure design and modeling research

To demonstrate the applicability of the control theory for distributed systems to large flexible space structures, research was focused on a model of a space antenna which consists of a rigid hub, flexible ribs, and a mesh reflecting surface. The space antenna model used is discussed along with the finite element approximation of the distributed model. The basic control problem is to design an optimal or near-optimal compensator to suppress the linear vibrations and rigid-body displacements of the structure. The application of an infinite dimensional Linear Quadratic Gaussian (LQG) control theory to flexible structure is discussed. Two basic approaches for robustness enhancement were investigated: loop transfer recovery and sensitivity optimization. A third approach synthesized from elements of these two basic approaches is currently under development. The control driven finite element approximation of flexible structures is discussed. Three sets of finite element basic vectors for computing functional control gains are compared. The possibility of constructing a finite element scheme to approximate the infinite dimensional Hamiltonian system directly, instead of indirectly is discussed

Human fur gene encodes a yeast KEX2-like endoprotease that cleaves pro-beta-NGF in vivo.

Extracts from BSC-40 cells infected with vaccinia recombinants expressing either the yeast KEX2 prohormone endoprotease or a human structural homologue (fur gene product) contained an elevated level of a membrane-associated endoproteolytic activity that could cleave at pairs of basic amino acids (-LysArg- and -ArgArg-). The fur-directed activity (furin) shared many properties with Kex2p including activity at pH 7.3 and a requirement for calcium. By using antifurin antibodies, immunoblot analysis detected two furin translation products (90 and 96 kD), while immunofluorescence indicated localization to the Golgi apparatus. Coexpression of either Kex2p or furin with the mouse beta-nerve growth factor precursor (pro-beta-NGF) resulted in greatly enhanced conversion of the precursor to mature nerve growth factor. Thus, the sequence homology shared by furin and the yeast KEX2 prohormone processing enzyme is reflected by significant functional homology both in vitro and in vivo

The X-Ray Properties of the Optically Brightest Mini-BAL Quasars from the Sloan Digital Sky Survey

We have compiled a sample of 14 of the optically brightest radio-quiet quasars ($m_{i}$~$\le$~17.5 and $z$~$\ge$~1.9) in the Sloan Digital Sky Survey Data Release 5 quasar catalog that have C IV mini-BALs present in their spectra. X-ray data for 12 of the objects were obtained via a Chandra snapshot survey using ACIS-S, while data for the other two quasars were obtained from archival XMM-Newton observations. Joint X-ray spectral analysis shows the mini-BAL quasars have a similar average power-law photon index ($\Gamma\approx1.9$) and level of intrinsic absorption ($N_H \lesssim 8\times 10^{21} \ {\rm cm}^{-2}$) as non-BMB (neither BAL nor mini-BAL) quasars. Mini-BAL quasars are more similar to non-BMB quasars than to BAL quasars in their distribution of relative X-ray brightness (assessed with $\Delta\alpha_{\rm ox}$). Relative colors indicate mild dust reddening in the optical spectra of mini-BAL quasars. Significant correlations between $\Delta\alpha_{\rm ox}$ and UV absorption properties are confirmed for a sample of 56 sources combining mini-BAL and BAL quasars with high signal-to-noise ratio rest-frame UV spectra, which generally supports models in which X-ray absorption is important in enabling driving of the UV absorption-line wind. We also propose alternative parametrizations of the UV absorption properties of mini-BAL and BAL quasars, which may better describe the broad absorption troughs in some respects.Comment: ApJ accepted; 21 pages, 11 figures, and 9 table

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

Constraints on Early Nucleosynthesis from the Abundance Pattern of a Damped Ly-alpha System at z = 2.626

We have investigated chemical evolution in the young universe by analysing the detailed chemical enrichment pattern of a metal-rich galaxy at high redshift. The recent detection of over 20 elements in the gas-phase of a damped Lyman-alpha absorber (DLA) at z = 2.626 represents an exciting new avenue for exploring early nucleosynthesis. Given a strict upper age of ~2.5 Gyr and a gas-phase metallicity about one third solar, we have shown the DLA abundance pattern to be consistent with the predictions of a chemical evolution model in which the interstellar enrichment is dominated by massive stars with a small contribution from Type Ia supernovae. Discrepancies between the empirical data and the models are used to highlight outstanding issues in nucleosynthesis theory, including a tendency for Type II supernovae models to overestimate the magnitude of the "odd-even" effect at subsolar metallicities. Our results suggest a possible need for supplemental sources of magnesium and zinc, beyond that provided by massive stars.Comment: 12 pages, 7 figs. Accepted for publication in ApJ (The Astrophysical Journal

Beagle to the Moon: nn experiment package to measure polar ice and volatiles in permanently shadowed areas or beneath the lunar surface

The Beagle Science Package is a flight qualified set of instruments which should be deployed to the lunar surface to answer the questions about water and volatiles present in permanently shadowed regions and/or beneath the surface