A Preliminary Examination of Age-Related Differences in Perceived Complexity at Fatal-Crash Intersections

Younger and older drivers are both overrepresented in fatal crashes that occur at intersections, however, after adjusting for other significant factors (i.e., being at fault type of road, weather, lighting) the increased risk cannot be fully accounted for older drivers, nor does frailty. Thus, increased risk for older drivers could be due to their agerelated cognitive declines and possible differences in perceptions of intersections. The current study examines whether older drivers’ perceived complexity of intersections differed quantitatively and qualitatively from younger drivers’ perceived complexity of the same intersections. Coordinates of a random sample of intersections where at least one fatality occurred over a three-year period from the US Fatality Analysis Reporting System (FARS) were identified and Google Earth was used to extract still images of each intersection. The complexity of these intersection images were rated by a sample (N =38) of younger (age 18-35) and older drivers (age 65+). Inter-rater reliability for each group was calculated. In addition, individual intersection images with the largest and smallest age differences were qualitatively examined. Results suggest that older drivers view the complexity of intersections differently than younger drivers. Overall, older drivers were less reliable and scored nominally higher on average in their complexity ratings than younger drivers. Moreover, older drivers tended to rate rural or residential intersections as being more complex than younger drivers; whereas younger drivers tended to rate urban intersections as being more complex. Future work should account for these age differences in perceived intersection complexity

Observations of Extrasolar Planets During the non-Cryogenic Spitzer Space Telescope Mission

Precision infrared photometry from Spitzer has enabled the first direct studies of light from extrasolar planets, via observations at secondary eclipse in transiting systems. Current Spitzer results include the first longitudinal temperature map of an extrasolar planet, and the first spectra of their atmospheres. Spitzer has also measured a temperature and precise radius for the first transiting Neptune-sized exoplanet, and is beginning to make precise transit timing measurements to infer the existence of unseen low mass planets. The lack of stellar limb darkening in the infrared facilitates precise radius and transit timing measurements of transiting planets. Warm Spitzer will be capable of a precise radius measurement for Earth-sized planets transiting nearby M-dwarfs, thereby constraining their bulk composition. It will continue to measure thermal emission at secondary eclipse for transiting hot Jupiters, and be able to distinguish between planets having broad band emission versus absorption spectra. It will also be able to measure the orbital phase variation of thermal emission for close-in planets, even non-transiting planets, and these measurements will be of special interest for planets in eccentric orbits. Warm Spitzer will be a significant complement to Kepler, particularly as regards transit timing in the Kepler field. In addition to studying close-in planets, Warm Spitzer will have significant application in sensitive imaging searches for young planets at relatively large angular separations from their parent stars.Comment: 12 pages, 7 figures, to appear in "Science Opportunities for the Warm Spitzer Mission

Under-Display Fingerprint Sensor System

This publication describes techniques for embedding an under-display fingerprint sensor (UDFPS) system, without increasing the thickness of an electronic device (e.g., smartphone) and/or decreasing the storage capacity of a battery of the smartphone. The described techniques allow a manufacturer to embed the UDFPS system outside the planar footprint of the battery of the smartphone. Also, these techniques enhance user experience by assembling the UDFPS system closer to the bottom edge of the smartphone, may enable the removal of a display flex support (backer), and may decrease the shear stress of a display bend of a display screen of the smartphone, increasing the mechanical strength the display screen

Adaptive User Interface for a Camera Aperture within an Active Display Area

This publication describes systems and techniques to account for an active display area around a camera aperture in a “hole-punch” style display of an electronic device to reduce a light-leaking effect caused by pixels surrounding the camera aperture. Illuminated pixels that are proximate to the camera aperture can degrade a quality of an image captured by a camera sensor by preventing the sensor from properly detecting light from a targeted image, such as a user’s face. To counteract this image degradation, techniques described herein override the illumination control for pixels surrounding the hole in the display. For example, responsive to the camera being engaged, one or more rings of pixels around the display hole can be controlled to have a decreased illumination level based on ambient brightness. The decreased illumination can involve being commanded to be turned off or being commanded to illuminate at a lower level. With less light emanating from pixels that are proximate to the display hole, there is less light pollution funneled into the camera aperture to affect the camera sensor

Applications of physical modeling to the investigations of air pollution problems in urban areas

CER73-74JEC-DJL-RST36.March 1974.Sponsored by National Science Foundation.Includes bibliographical references.Wind tunnel modeling of atmospheric flow and diffusion in the boundary layer over an urban area are discussed. Measurements were made over a model of an urban area composed of a network of uniform city blocks and streets. Two line sources emitting a radioactive tracer gas represented automobile emissions in a one-block length of a city street. Pollutant concentrations were calculated from samples of the tracer gas collected on building faces, in street canyons, and in the flow field above the model. Non dimensionalized concentration patterns were constructed from the analysis of the samples. Three wind directions were considered. The effects of a simple modification of the uniform model were evaluated.Under grant GI-34813X

The DEEP2 Galaxy Redshift Survey: Redshift Identification of Single-Line Emission Galaxies

We present two methods for determining spectroscopic redshifts of galaxies in the DEEP2 survey which display only one identifiable feature, an emission line, in the observed spectrum ("single-line galaxies"). First, we assume each single line is one of the four brightest lines accessible to DEEP2: Halpha, [OIII] 5007, Hbeta, or [OII] 3727. Then, we supplement spectral information with BRI photometry. The first method, parameter space proximity (PSP), calculates the distance of a single-line galaxy to galaxies of known redshift in (B-R), (R-I), R, observed wavelength parameter space. The second method is an artificial neural network (ANN). Prior information, such as allowable line widths and ratios, rules out one or more of the four lines for some galaxies in both methods. Based on analyses of evaluation sets, both methods are nearly perfect at identifying blended [OII] doublets. Of the lines identified as Halpha in the PSP and ANN methods, 91.4% and 94.2% respectively are accurate. Although the methods are not this accurate at discriminating between [OIII] and Hbeta, they can identify a single line as one of the two, and the ANN method in particular unambiguously identifies many [OIII] lines. From a sample of 640 single-line spectra, the methods determine the identities of 401 (62.7%) and 472 (73.8%) single lines, respectively, at accuracies similar to those found in the evaluation sets.Comment: 11 pages, 6 figures, accepted to Ap

Simulations of Damped Lyman-Alpha and Lyman Limit Absorbers in Different Cosmologies: Implications for Structure Formation at High Redshift

We use hydrodynamic cosmological simulations to study damped Lyman-alpha (DLA) and Lyman limit (LL) absorption at redshifts z=2-4 in five variants of the cold dark matter scenario. Our standard simulations resolve the formation of dense concentrations of neutral gas in halos with circular velocity v_c roughly 140 km/s for Omega_m=1 and 90 km/s for Omega_m=0.4, at z=2; an additional LCDM simulation resolves halos down to v_c approximately 50 km/s at z=3. We find a clear relation between HI column density and projected distance to the center of the nearest galaxy, with DLA absorption usually confined to galactocentric radii less than 10-15 kpc and LL absorption arising out to projected separations of 30 kpc or more. Detailed examination provides evidence of non-equilibrium effects on absorption cross-section. If we consider only absorption in the halos resolved by our standard simulations, then all five models fall short of reproducing the observed abundance of DLA and LL systems at these redshifts. If we extrapolate to lower halo masses, we find all four models are consistent with the observed abundance of DLA systems if the the extrapolated behavior extends to circular velocities roughly 50-80 km/s, and they may produce too much absorption if the relation continues to 40 km/s. Our results suggest that LL absorption is closely akin to DLA absorption, arising in less massive halos or at larger galactocentric radii but not caused by processes acting on a radically different mass scale.Comment: 33 pages with 10 embedded EPS figures. Substantially revised and updated from original version. Includes new high-resolution simulations. Accepted for publication in the Ap

Robust Machine Learning Applied to Astronomical Datasets I: Star-Galaxy Classification of the SDSS DR3 Using Decision Trees

We provide classifications for all 143 million non-repeat photometric objects in the Third Data Release of the Sloan Digital Sky Survey (SDSS) using decision trees trained on 477,068 objects with SDSS spectroscopic data. We demonstrate that these star/galaxy classifications are expected to be reliable for approximately 22 million objects with r < ~20. The general machine learning environment Data-to-Knowledge and supercomputing resources enabled extensive investigation of the decision tree parameter space. This work presents the first public release of objects classified in this way for an entire SDSS data release. The objects are classified as either galaxy, star or nsng (neither star nor galaxy), with an associated probability for each class. To demonstrate how to effectively make use of these classifications, we perform several important tests. First, we detail selection criteria within the probability space defined by the three classes to extract samples of stars and galaxies to a given completeness and efficiency. Second, we investigate the efficacy of the classifications and the effect of extrapolating from the spectroscopic regime by performing blind tests on objects in the SDSS, 2dF Galaxy Redshift and 2dF QSO Redshift (2QZ) surveys. Given the photometric limits of our spectroscopic training data, we effectively begin to extrapolate past our star-galaxy training set at r ~ 18. By comparing the number counts of our training sample with the classified sources, however, we find that our efficiencies appear to remain robust to r ~ 20. As a result, we expect our classifications to be accurate for 900,000 galaxies and 6.7 million stars, and remain robust via extrapolation for a total of 8.0 million galaxies and 13.9 million stars. [Abridged]Comment: 27 pages, 12 figures, to be published in ApJ, uses emulateapj.cl

The Population of Damped Lyman-alpha and Lyman Limit Systems in the Cold Dark Matter Model

Lyman limit and damped Lyman-alpha absorption systems probe the distribution of collapsed, cold gas at high redshift. Numerical simulations that incorporate gravity and gas dynamics can predict the abundance of such absorbers in cosmological models. We develop a semi-analytical method to correct the numerical predictions for the contribution of unresolved low mass halos, and we apply this method to the Katz et al. (1996) simulation of the standard cold dark matter model ($\Omega=1$, $h=0.5$, $\Omega_b=0.05$, $\sigma_8=0.7$). Using this simulation and higher resolution simulations of individual low mass systems, we determine the relation between a halo's circular velocity $v_c$ and its cross section for producing Lyman limit or damped absorption. We combine this relation with the Press-Schechter formula for the abundance of halos to compute the number of absorbers per unit redshift. The resolution correction increases the predicted abundances by about a factor of two at z=2, 3, and 4, bringing the predicted number of damped absorbers into quite good agreement with observations. Roughly half of the systems reside in halos with circular velocities v_c>100\kms and half in halos with 35\kms. Halos with v_c>150\kms typically harbor two or more systems capable of producing damped absorption. Even with the resolution correction, the predicted abundance of Lyman limit systems is a factor of three below observational estimates, signifying either a failure of standard CDM or a failure of these simulations to resolve the systems responsible for most Lyman limit absorption. By comparing simulations with and without star formation, we find that depletion of the gas supply by star formation affects absorption line statistics at $z>=2$ only for column densities exceeding $N_{HI}=10^{22} cm^{-2}$.Comment: AASlatex, 17 pages w/ 3 embedded ps figures. Submitted to Ap

Discovery of Damped Lyman-Alpha Systems at Redshifts Less Than 1.65 and Results on their Incidence and Cosmological Mass Density

We report results on the incidence and cosmological mass density of damped Lyman-alpha (DLA) systems at redshifts less that 1.65. We used HST and an efficient non-traditional (but unbiased) survey technique to discover DLA systems at redshifts z<1.65, where we observe the Lyman-alpha line in known MgII absorption-line systems. We uncovered 14 DLA lines including 2 serendipitously. We find that (1) The DLA absorbers are drawn almost exclusively from the population of MgII absorbers which have rest equivalent widths W(2796)>0.6A. (2) The incidence of DLA systems per unit redshift, n(DLA), is observed to decrease with decreasing redshift. (3) On the other hand, the cosmological mass density of neutral gas in low-redshift DLA absorbers, Omega(DLA), is observed to be comparable to that observed at high redshift. (4) The low-redshift DLA absorbers exhibit a significantly larger fraction of very high column density systems in comparison to determinations at both high redshift and locally.Comment: 47 pages in LaTeX - emulateapj style with included tables and encapsulated postscript figures. Accepted for Publication in Astrophysical Journal Supplements. Results unchanged, text revise