The X-Ray Position and Infrared Counterpart of the Eclipsing X-Ray Pulsar OAO 1657-415

We have measured the precise position of the 38-s eclipsing X-ray pulsar OAO 1657-415 with the Chandra X-Ray Observatory: RA = 17h00m48.90s, Dec = -41d39m21.6s, equninox J2000, error radius = 0.5 arcsec. Based on the previously measured pulsar mass function and X-ray eclipse duration, this 10.4-d high-mass X-ray binary is believed to contain a B supergiant companion. Deep optical imaging of the field did not detect any stars at the Chandra source position, setting a limit of V>23. However, near-IR imaging revealed a relatively bright star (J=14.1, H=11.9, K_s=10.7) coincident with the Chandra position, and we identify this star as the IR counterpart of OAO 1657-415. The IR colors and magnitudes and the optical non-detections for this star are all consistent with a highly reddened B supergiant (A_V= 20.4 +/- 1.3) at a distance of 6.4 +/- 1.5 kpc. This implies an X-ray luminosity of 3e36 erg/s (2-10 keV). IR spectroscopy can verify the spectral type of the companion and measure its radial velocity curve, yielding a neutron star mass measurement.Comment: 4 pages. ApJ in press (Vol. 573, July 10 issue

The Missions and Camino Real of Baja California: A Binational View

From the end of the seventeenth century through the early nineteenth century, missionaries from the Jesuit, Franciscan, and Dominican orders founded numerous missions in Baja California. In this article we introduce readers in Alta California to these missions, which along with El Camino Real de las Californias, were the most important institutions used by the Spanish Crown to colonize the Pacific coast of North America

Professional Development for the Integration of Engineering in High School STEM Classrooms

Science, Technology, Engineering, and Mathematics (STEM) education in the U.S. is in transition. The recently published A Framework for K-12 Science Education: Practices, Crosscutting Concepts, and Core Ideas as well as the Next Generation Science Standards are responsive to this call and clearly articulate a vision that includes engineering practices as key components. This shift presents significant challenges to school districts owing to a stark lack of research-based engineering-focused instructional materials and corresponding teacher professional development. The purpose of this study was to investigate the impact of a professional development program on high school STEM teachers’ ability to enact design-based pedagogical practices associated with the pre-selected engineering design curriculum (INSPIRES Engineering in Healthcare: A Heart-Lung System Case Study). Data were generated through evaluation of teacher practice using the Reformed Teaching Observation Protocol (RTOP). Findings demonstrated that RTOP scores were statistically significant

Non-relativistic Maxwell-Chern-Simons Vortices

The non-relativistic Maxwell-Chern-Simons model recently introduced by Manton is shown to admit self-dual vortex solutions with non-zero electric field. The interrelated ``geometric'' and ``hidden'' symmetries are explained. The theory is also extended to (non-relativistic) spinors. A relativistic, self-dual model, whose non-relativistic limit is the Manton model is also presented. The relation to previous work is discussed.Comment: 20 pages plain TeX. Revised: minor errors corrected and symmetries explained in a clearer way. Version as will appear in Ann. Phys. (N.Y.

Effect of Grazing Frequency by Dairy Cows on Herb Based Pastures

Herbage production and quality of perennial ryegrass pastures is often limited over the summer months (Powell et al. 2007). Chicory (Cichorium intybus L.) and narrow-leaf plantain (Plantago lanceolata L.) are perennial herbs that accumulate high herbage masses during late spring and summer (Powell et al 2007; Li and Kemp 2005). These perennial herbs are being used by farmers to supplement dairy cows over summer. However, there have been many cases of poor plant persistence with current management practices. The aim of this research was to determine the effect of two grazing frequencies (GF; 2 weeks and 4 weeks) on the herbage production and persistence of pure swards of chicory, plantain and a herb-clover mix (chicory, plantain, red and white clover) over a single growing season