Statistical Methods for Evaluating and Comparing Biomarkers for Patient Treatment Selection

Despite the heightened interest in developing biomarkers predicting treatment response that are used to optimize patient treatment decisions, there has been relatively little development of statistical methodology to evaluate these markers. There is currently no unified statistical framework for marker evaluation. This paper proposes a suite of descriptive and inferential methods designed to evaluate individual markers and to compare candidate markers. An R software package has been developed which implements these methods. Their utility is illustrated in the breast cancer treatment context, where candidate markers are evaluated for their ability to identify a subset of women who do not benefit from adjuvant chemotherapy and can therefore avoid its toxicity

Proposal for a low cost close air support aircraft for the year 2000: The Raptor

The Raptor is a proposed low cost Close Air Support (CAS) aircraft for the U.S. Military. The Raptor incorporates a 'cranked arrow' wing planform, and uses canards instead of a traditional horizontal tail. The Raptor is designed to be capable of responsive delivery of effective ordnance in close proximity to friendly ground forces during the day, night, and 'under the weather' conditions. Details are presented of the Raptor's mission, configuration, performance, stability and control, ground support, manufacturing, and overall cost to permit engineering evaluation of the proposed design. A description of the design process and analysis methods used is also provided

Effects of cochlear implantation on binaural hearing in adults with unilateral hearing loss

A FDA clinical trial was carried out to evaluate the potential benefit of cochlear implant (CI) use for adults with unilateral moderate-to-profound sensorineural hearing loss. Subjects were 20 adults with moderate-to-profound unilateral sensorineural hearing loss and normal or near-normal hearing on the other side. A MED-EL standard electrode was implanted in the impaired ear. Outcome measures included: (a) sound localization on the horizontal plane (11 positions, −90° to 90°), (b) word recognition in quiet with the CI alone, and (c) masked sentence recognition with the target at 0° and the masker at −90°, 0°, or 90°. This battery was completed preoperatively and at 1, 3, 6, 9, and 12 months after CI activation. Normative data were also collected for 20 age-matched control subjects with normal or near-normal hearing bilaterally. The CI improved localization accuracy and reduced side bias. Word recognition with the CI alone was similar to performance of traditional CI recipients. The CI improved masked sentence recognition when the masker was presented from the front or from the side of normal or near-normal hearing. The binaural benefits observed with the CI increased between the 1- and 3-month intervals but appeared stable thereafter. In contrast to previous reports on localization and speech perception in patients with unilateral sensorineural hearing loss, CI benefits were consistently observed across individual subjects, and performance was at asymptote by the 3-month test interval. Cochlear implant settings, consistent CI use, and short duration of deafness could play a role in this result

UV excess galaxies: Wolf-Rayet galaxies

We discuss V and R band photometry for 67% of the Sullivan et al. 2000 SA57 ultraviolet-selected galaxy sample. In a sample of 176 UV-selected galaxies, Sullivan et al. 2000 find that 24% have (UV-B) colors too blue for consistency with starburst spectral synthesis models. We propose that these extreme blue, UV excess galaxies are Wolf-Rayet (WR) galaxies, starburst galaxies with strong UV emission from WR stars. We measure a median (V-R)=0.38+-0.06 for the UV-selected sample, bluer than a sample optically selected at R but consistent with starburst and WR galaxy colors. We demonstrate that redshifted WR emission lines can double or triple the flux through the UV bandpass at high redshifts. Thus the (UV-B) color of a WR galaxy can be up to 1.3 mag bluer at high redshift, and the expected selection function is skewed to larger redshifts. The redshift distribution of the extreme blue, UV excess galaxies matches the selection function we predict from the properties of WR galaxies.Comment: 4 pages, including 4 figures. Uses AASTeX and emulateapj5.sty. Includes referee change

Discovery of an Unbound Hyper-Velocity Star in the Milky Way Halo

We have discovered a star, SDSS J090745.0+024507, leaving the Galaxy with a heliocentric radial velocity of +853+-12 km/s, the largest velocity ever observed in the Milky Way halo. The star is either a hot blue horizontal branch star or a B9 main sequence star with a heliocentric distance ~55 kpc. Corrected for the solar reflex motion and to the local standard of rest, the Galactic rest-frame velocity is +709 km/s. Because its radial velocity vector points 173.8 deg from the Galactic center, we suggest that this star is the first example of a hyper-velocity star ejected from the Galactic center as predicted by Hills and later discussed by Yu & Tremaine. The star has [Fe/H]~0, consistent with a Galactic center origin, and a travel time of <80 Myr from the Galactic center, consistent with its stellar lifetime. If the star is indeed traveling from the Galactic center, it should have a proper motion of 0.3 mas/yr observable with GAIA. Identifying additional hyper-velocity stars throughout the halo will constrain the production rate history of hyper-velocity stars at the Galactic center.Comment: 4 pages, submitted to ApJ Letter

MMT Extremely Metal Poor Galaxy Survey I. An Efficient Technique to Identify Metal Poor Galaxies

We demonstrate a successful strategy for identifying extremely metal poor galaxies. Our preliminary survey of 24 candidates contains 10 metal poor galaxies of which 4 have 12+log(O/H)<7.65, some of the lowest metallicity blue compact galaxies known to date. Interestingly, our sample of metal poor galaxies have systematically lower metallicity for their luminosity than comparable samples of blue compact galaxies, dIrrs, and normal star-forming galaxies. Our metal poor galaxies share very similar properties, however, with the host galaxies of nearby long-duration gamma-ray bursts (GRBs), including similar metallicity, stellar ages, and star formation rates. We use H\beta to measure the number of OB stars present in our galaxies and estimate a core-collapse supernova rate of ~10^-3 yr^-1. A larger sample of metal poor galaxies may provide new clues into the environment where GRBs form and may provide a list of potential GRB hosts.Comment: Accepted to AJ, 8 pages using emulateap