A high resolution UV absorption spectrum of supernova ejecta in SN1006

We report a high resolution, far-ultraviolet, STIS E140M spectrum of the strong, broad Si II, III, and IV features produced by the ejecta of SN1006 seen in absorption against the background Schweizer-Middleditch star. The spectrum confirms the extreme sharpness of the red edge of the redshifted Si II 1260 A feature, supporting the idea that this edge represents the location of the reverse shock moving into the freely expanding ejecta. The expansion velocity of ejecta at the reverse shock is measured to be 7026 +-3(relative) +-10(absolute) km/s. If the shock model is correct, then the expansion velocity should be decreasing at the observable rate of 2.7 +-0.1 km/s per year. The pre-shock velocity, post-shock velocity, and post-shock velocity dispersion are all measured from the Si II 1260 A feature, and consistency of these velocities with the shock jump conditions implies that there is little or no electron heating in this fast (2680 km/s) Si-rich shock.Comment: 9 pages, 5 embedded postscript fig

A Microfluidic Platform for Precision Small-volume Sample Processing and Its Use to Size Separate Biological Particles with an Acoustic Microdevice.

A major advantage of microfluidic devices is the ability to manipulate small sample volumes, thus reducing reagent waste and preserving precious sample. However, to achieve robust sample manipulation it is necessary to address device integration with the macroscale environment. To realize repeatable, sensitive particle separation with microfluidic devices, this protocol presents a complete automated and integrated microfluidic platform that enables precise processing of 0.15-1.5 ml samples using microfluidic devices. Important aspects of this system include modular device layout and robust fixtures resulting in reliable and flexible world to chip connections, and fully-automated fluid handling which accomplishes closed-loop sample collection, system cleaning and priming steps to ensure repeatable operation. Different microfluidic devices can be used interchangeably with this architecture. Here we incorporate an acoustofluidic device, detail its characterization, performance optimization, and demonstrate its use for size-separation of biological samples. By using real-time feedback during separation experiments, sample collection is optimized to conserve and concentrate sample. Although requiring the integration of multiple pieces of equipment, advantages of this architecture include the ability to process unknown samples with no additional system optimization, ease of device replacement, and precise, robust sample processing

A High-Resolution Ultraviolet Absorption Spectrum of Supernova Ejecta in SN1006

We report a high-resolution, far-ultraviolet, Space Telescope Imaging Spectrograph (STIS) E140M spectrum of the strong, broad Siii, iii and iv features produced by the ejecta of the supernova of 1006 ad (SN1006) seen in absorption against the background Schweizer–Middleditch OB subdwarf star. The spectrum confirms the extreme sharpness of the red edge of the redshifted Si ii 1260 Å feature, supporting the idea that this edge represents the location of the reverse shock moving into the freely expanding Si-rich ejecta. The expansion velocity of ejecta at the reverse shock is measured to be 7026 ± 3(relative) ±10(absolute) km s−1. If the shock model is correct, then the expansion velocity should be decreasing at the observable rate of 2.7 ± 0.1 km s−1 yr−1. The pre-shock velocity, post-shock velocity and post-shock velocity dispersion are all measured from the Si ii 1260 Å feature, and consistency of these velocities with the shock jump conditions implies that there is little or no electron heating in this fast (2680 km s−1) Si-rich shock; the 3σ upper limit on the fraction of shock energy that goes into electron heating is 0.26

The Boston equalens: A clinical evaluation for wear

Recent advances in gas permeable contact lens materials have accounted for their successful use in extended wear. In this study, 18 subjects were fitted with the Boston Equalens, a new silicon/acrylate lens which is combined with a flourinated monomer. The subjects wore one lens as a daily wear contact lens and the other lens as an extended wear contact lens for a period of 90 days. Four patients successfully completed the 90 days of extended wear and five patients completed between 30 and 90 days of extended wear. No significant differences of corneal curvature, refractive error, corrected visual acuity, or subjective responses were noted between the daily wear eye and the extended wear eye. Also there were no reports of lens adhesion on any of the subjects\u27 eyes

Bostonia. Volume 11

Founded in 1900, Bostonia magazine is Boston University's main alumni publication, which covers alumni and student life, as well as university activities, events, and programs

Fundamental representations and algebraic properties of biquaternions or complexified quaternions

The fundamental properties of biquaternions (complexified quaternions) are presented including several different representations, some of them new, and definitions of fundamental operations such as the scalar and vector parts, conjugates, semi-norms, polar forms, and inner and outer products. The notation is consistent throughout, even between representations, providing a clear account of the many ways in which the component parts of a biquaternion may be manipulated algebraically