10,863 research outputs found
Comments Made in Response to “Studying Intercollegiate Sports: High Stakes, Low Rewards” by Dr. Jay Coakley
Determining the Extent of Market and Extent of Resource for Stated Preference Survey Design Using Mapping Methods
Determining the appropriate survey population and the commodity to be valued are among the most fundamental design decisions for stated preference (SP) surveys. However, often little information is available about who in the population holds measurable value for the resource (the extent of the market) and their perceptions regarding the scope of the resource to be valued (the extent of the resource). In this paper, we present a novel approach using cognitive mapping interview techniques to shed light on these design questions. The method also provides ancillary information that assists in the interpretation of information collected during focus groups and through SP survey administration. The approach was developed and tested as part of an ongoing study on environmental degradation associated with acidification in the Southern Appalachian Mountain region. Although damage from acidification in the study region is broad, it is not clear whether residents of this region care, in both a use and nonuse sense, about resources in their states of residence, in neighboring states, on public lands, or more broadly across the region. From a pilot study, we found that participants show a significant home-state preference in the number and size of natural areas that they value within the larger Southern Appalachian Mountain region. However, this preference is not strong enough to suggest that the market for improving these resources is solely constrained to residents of the state in which the resource is located.stated preference, cognitive mapping, extent of market, extent of resource, definition of commodity
Unifying Amplitude and Phase Analysis: A Compositional Data Approach to Functional Multivariate Mixed-Effects Modeling of Mandarin Chinese
Mandarin Chinese is characterized by being a tonal language; the pitch (or
) of its utterances carries considerable linguistic information. However,
speech samples from different individuals are subject to changes in amplitude
and phase which must be accounted for in any analysis which attempts to provide
a linguistically meaningful description of the language. A joint model for
amplitude, phase and duration is presented which combines elements from
Functional Data Analysis, Compositional Data Analysis and Linear Mixed Effects
Models. By decomposing functions via a functional principal component analysis,
and connecting registration functions to compositional data analysis, a joint
multivariate mixed effect model can be formulated which gives insights into the
relationship between the different modes of variation as well as their
dependence on linguistic and non-linguistic covariates. The model is applied to
the COSPRO-1 data set, a comprehensive database of spoken Taiwanese Mandarin,
containing approximately 50 thousand phonetically diverse sample contours
(syllables), and reveals that phonetic information is jointly carried by both
amplitude and phase variation.Comment: 49 pages, 13 figures, small changes to discussio
Searching for Machos (and other Dark Matter Candidates) in a Simulated Galaxy
We conduct gravitational microlensing experiments in a galaxy taken from a
cosmological N-body simulation. Hypothetical observers measure the optical
depth and event rate toward hypothetical LMCs and compare their results with
model predictions. Since we control the accuracy and sophistication of the
model, we can determine how good it has to be for statistical errors to
dominate over systematic ones. Several thousand independent microlensing
experiments are performed. When the ``best-fit'' triaxial model for the mass
distribution of the halo is used, the agreement between the measured and
predicted optical depths is quite good: by and large the discrepancies are
consistent with statistical fluctuations. If, on the other hand, a spherical
model is used, systematic errors dominate. Even with our ``best-fit'' model,
there are a few rare experiments where the deviation between the measured and
predicted optical depths cannot be understood in terms of statistical
fluctuations. In these experiments there is typically a clump of particles
crossing the line of sight to the hypothetical LMC. These clumps can be either
gravitationally bound systems or transient phenomena in a galaxy that is still
undergoing phase mixing. Substructure of this type, if present in the Galactic
distribution of Machos, can lead to large systematic errors in the analysis of
microlensing experiments. We also describe how hypothetical WIMP and axion
detection experiments might be conducted in a simulated N-body galaxy.Comment: 18 pages of text (LaTeX, AASTeX) with 12 figures. submitted to the
Astrophysical Journa
Reduced heterozygosity impairs sperm quality in endangered mammals
Inbreeding causes increases in homozygosity and is commonly associated with reductions in fertility and embryogenesis. Although the mechanisms underlying such effects are unknown, recent work has suggested that inbred males may suffer impaired ejaculate quality, thus providing a functional explanation for reductions in reproductive function in inbred populations. However, the relationship between inbreeding and sperm quality remains controversial, particularly in wild populations where the level of inbreeding is typically estimated using neutral molecular markers. Such markers are thought to reflect genome-wide levels of heterozygosity only under restricted conditions, and rarely in outbred populations. Here we employ a comparative approach that takes account of these criticisms and evaluates the evidence linking inbreeding to reductions in sperm quality in 20 mammal species. We focus on sperm abnormalities and sperm motility, which are key determinants of male fertility in many species. We show that species with reduced mean heterozygosity have impaired ejaculated quality, although subsequent analyses revealed that these effects were confined to endangered populations. Our findings therefore support the notion that inbreeding can severely impair sperm quality while concomitantly addressing criticisms surrounding the use of heterozygosity estimates to estimate the level of inbreeding
Validation of a fornix depth measurer: a putative tool for the assessment of progressive cicatrising conjunctivitis
Background/aims Documentation of conjunctival forniceal foreshortening in cases of progressive cicatrising conjunctivitis (PCC) is important in ascertaining disease stage and progression. Lower fornix shortening is often documented subjectively or semi-objectively, whereas upper forniceal obliteration is seldom quantified. Although tools such as fornix depth measurers (FDMs) have been described, their designs limit upper fornix measurement. The purpose of this study was to custom-design a FDM to evaluate the upper fornix and to assess variability in gauging fornix depth. \ud
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Methods A polymethylmethacrylate FDM was constructed using industry-standard jewellery computer software and machinery. Two observers undertook a prospective independent evaluation of central lower fornix depth in a heterogeneous cohort of patients with clinically normal and abnormal conjunctival fornices both subjectively and by using the FDM (in mm). Upper central fornix depth was also measured. Agreement was assessed using Bland–Altman plots. \ud
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Results Fifty-one eyes were evaluated. There was 100% intraobserver agreement to within 1 mm for each observer for lower fornix measurement. The mean difference in fornix depth loss using the FDM between observer 1 and 2 was 1.19%, with 95% confidence of agreement (±2SD) of −15% to +20%. In total, 86% (44/51) of measurements taken by the two observers agreed to within 10% of total lower fornix depth (ie, ±1 mm) versus only 63% (32/51) of the subjective measurements. Mean upper fornix difference was 0.57 mm, with 95% confidence of agreement of between −2 and + 3 mm. \ud
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Conclusions This custom-designed FDM is well tolerated by patients and shows low intraobserver and interobserver variability. This enables repeatable and reproducible measurement of upper and lower fornix depths, facilitating improved rates of detection and better monitoring of progression of conjunctival scarring
Investigation of the use of the thermal decomposition of nitrous oxide to produce hypersonic flow of a gas closely resembling air
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Geodetic Constraints on San Francisco Bay Area Fault Slip Rates and Potential Seismogenic Asperities on the Partially Creeping Hayward Fault
The Hayward fault in the San Francisco Bay Area (SFBA) is sometimes considered unusual among continental faults for exhibiting significant aseismic creep during the interseismic phase of the seismic cycle while also generating sufficient elastic strain to produce major earthquakes. Imaging the spatial variation in interseismic fault creep on the Hayward fault is complicated because of the interseismic strain accumulation associated with nearby faults in the SFBA, where the relative motion between the Pacific plate and the Sierra block is partitioned across closely spaced subparallel faults. To estimate spatially variable creep on the Hayward fault, we interpret geodetic observations with a three-dimensional kinematically consistent block model of the SFBA fault system. Resolution tests reveal that creep rate variations with a length scale of <15 km are poorly resolved below 7 km depth. In addition, creep at depth may be sensitive to assumptions about the kinematic consistency of fault slip rate models. Differential microplate motions result in a slip rate of 6.7 ± 0.8 mm/yr on the Hayward fault, and we image along-strike variations in slip deficit rate at ∼15 km length scales shallower than 7 km depth. Similar to previous studies, we identify a strongly coupled asperity with a slip deficit rate of up to 4 mm/yr on the central Hayward fault that is spatially correlated with the mapped surface trace of the 1868 Hayward earthquake and adjacent to gabbroic fault surfaces.Earth and Planetary Science
Orbital-Free Density Functional Theory: Kinetic Potentials and Ab-Initio Local Pseudopotentials
In the density functional (DF) theory of Kohn and Sham, the kinetic energy of
the ground state of a system of noninteracting electrons in a general external
field is calculated using a set of orbitals. Orbital free methods attempt to
calculate this directly from the electron density by approximating the
universal but unknown kinetic energy density functional. However simple local
approximations are inaccurate and it has proved very difficult to devise
generally accurate nonlocal approximations. We focus instead on the kinetic
potential, the functional derivative of the kinetic energy DF, which appears in
the Euler equation for the electron density. We argue that the kinetic
potential is more local and more amenable to simple physically motivated
approximations in many relevant cases, and describe two pathways by which the
value of the kinetic energy can be efficiently calculated. We propose two
nonlocal orbital free kinetic potentials that reduce to known exact forms for
both slowly varying and rapidly varying perturbations and also reproduce exact
results for the linear response of the density of the homogeneous system to
small perturbations. A simple and systematic approach for generating accurate
and weak ab-initio local pseudopotentials which produce a smooth slowly varying
valence component of the electron density is proposed for use in orbital free
DF calculations of molecules and solids. The use of these local
pseudopotentials further minimizes the possible errors from the kinetic
potentials. Our theory yields results for the total energies and ionization
energies of atoms, and for the shell structure in the atomic radial density
profiles that are in very good agreement with calculations using the full
Kohn-Sham theory.Comment: To be published in Phys. Rev.
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