Fashionably Late? Building up the Milky Way's Inner Halo

Using a sample of 248 metal-poor stars (RR Lyraes, red giants and RHB stars) which is remarkable for the accuracy of its 6-D kinematical data, we find a new component for the local halo which has an axial ratio c/a ~ 0.2, a similar flattening to the thick disk. It has a small prograde rotation but is supported by velocity anisotropy, and contains more intermediate-metallicity stars (with -1.5 < [Fe/H] < -1.0) than the rest of our sample. We suggest that this component was formed quite late, during or after the formation of the disk. It formed either from the gas that was accreted by the last major mergers experienced by the Galaxy, or by dynamical friction of massive infalling satellite(s) with the halo and possibly the stellar disk or thick disk. The remainder of the stars in our sample exhibit a clumpy distribution in energy and angular momentum, suggesting that the early, chaotic conditions under which the inner halo formed were not violent enough to erase the record of their origins. The clumpy structure suggests that a relatively small number of progenitors were responsible for building up the inner halo, in line with theoretical expectations. We find a difference in mean binding energy between the RR Lyrae variables and the red giants in our sample, suggesting that more of the RR Lyraes in the sample belong to the outer halo, and that the outer halo may be somewhat younger, as first suggested by Searle and Zinn (1978). We also find that the RR Lyrae mean rotation is more negative than the red giants, which is consistent with the recent result of Carollo et al.(2007) that the outer halo has a retrograde rotation and with the difference in kinematics seen between RR Lyraes and BHB stars by Kinman et al.(2007).Comment: 16 pages, 10 figures, this version accepted by Ap

Technical report (Texas Transportation Institute)

An implementation project was performed to expand use of transversely varied asphalt rate (TVAR) seal coat practices in all districts. The project included nine regional workshops, continued field texture testing of test sites, provided one set of sand patch test equipment to each Texas Department of Transportation (TxDOT) district, and published 500 copies of the TVAR Field Guide for broad TxDOT distribution

A Dynamic Programming Optimization Approach for Budget Allocation to Early Right-of-Way Acquisitions

Maximizing potential savings when purchasing right-of-way within a limited budget is a challenge currently faced by state departments of transportation (DOTs) across the nation. Early right-ofway acquisitions promote smoother negotiations and are aimed to save money, time, and human resources. This paper describes an optimization approach based on dynamic programming developed for the Texas Department of Transportation (TxDOT) to identify projects with candidate parcels for early right-of-way acquisition in order to achieve the highest potential savings. Each candidate parcel must be subjected to a preliminary environmental analysis to ensure that each comply with the National Environmental Policy Act (NEPA) standards

Technical report (Texas Transportation Institute)

" This report documents the work performed during Project 0-6387, "Performance Based Roadside Maintenance Specifications."

Technical report (Texas Transportation Institute)

This report documents research efforts to provide comparative quantitative performance information for various grades of seal coat aggregate available in the Texas Department of Transportation standard specifications. Length of service before replacement and level of noise generated at the tire-pavement interface were the primary focuses of the relative performance evaluations. The additional service life possible from seal coats with larger aggregate and higher asphalt application rates is compared to the additional cost generally associated with these larger aggregate seal coats. The comparative performance information combined with knowledge gathered from numerous department field engineers resulted in the development of guidelines for optimal seal coat grade selection