The Interpreter In An Undergraduate Compilers Course

An undergraduate compilers course poses significant challenges to students, in both the conceptual richness of the major components and in the programming effort necessary to implement them. In this paper, I argue that a related architecture, the interpreter, serves as an effective conceptual framework in which to teach some of the later stages of the compiler pipeline. This framework can serve both to unify some of the major concepts that are taught in a typical undergraduate course and to structure the implementation of a semester-long compiler project.Comment: Final version to appear in SIGCSE '1

SOFIA/EXES Observations of Water Absorption in the Protostar AFGL 2591 at High Spectral Resolution

We present high spectral resolution (~3 km/s) observations of the nu_2 ro-vibrational band of H2O in the 6.086--6.135 micron range toward the massive protostar AFGL 2591 using the Echelon-Cross-Echelle Spectrograph (EXES) on the Stratospheric Observatory for Infrared Astronomy (SOFIA). Ten absorption features are detected in total, with seven caused by transitions in the nu_2 band of H2O, two by transitions in the first vibrationally excited nu_2 band of H2O, and one by a transition in the nu_2 band of H2{18}O. Among the detected transitions is the nu_2 1(1,1)--0(0,0) line which probes the lowest lying rotational level of para-H2O. The stronger transitions appear to be optically thick, but reach maximum absorption at a depth of about 25%, suggesting that the background source is only partially covered by the absorbing gas, or that the absorption arises within the 6 micron emitting photosphere. Assuming a covering fraction of 25%, the H2O column density and rotational temperature that best fit the observed absorption lines are N(H2O)=(1.3+-0.3)*10^{19} cm^{-2} and T=640+-80 K.Comment: 6 pages, 3 figures, 1 table, accepted for publication in ApJ

Instability of a four-dimensional de Sitter black hole with a conformally coupled scalar field

We study the stability of new neutral and electrically charged four-dimensional black hole solutions of Einstein's equations with a positive cosmological constant and conformally coupled scalar field. The neutral black holes are always unstable. The charged black holes are also shown analytically to be unstable for the vast majority of the parameter space of solutions, and we argue using numerical techniques that the configurations corresponding to the remainder of the parameter space are also unstable.Comment: revtex4, 8 pages, 4 figures, minor changes, accepted for publication in Phys. Rev.

Worst Case Scenarios in Soccer Training and Competition: Analysis of Playing Position, Congested Periods, and Substitutes

Aim: To understand mean (WCSₘₑₐₙ) and peak (WCSₚₑₐₖ) worst case scenarios within training and game play in male professional soccer. Methods: Thirty-one (n = 31) first team players were monitored across 37 matches and 14 MD-3 sessions. Playing status was distinguished, football drills analyzed, and performance explored in long-period: >6 days, moderate-period: 5–6 days, and congested-period: ≤4 days. Relative total distance (TD), high-speed running distance (HSRD, >19.8 km·h⁻¹), sprint distance (SD, >25.2 km·h⁻²), accelerations/decelerations (A+D, >3 m·s⁻²), accelerations (Acc, >3 m·s⁻²), and decelerations (Dec, >−3 m·s⁻²) were measured as well as Maximum acceleration (Max Acc; m·s⁻²) and deceleration (Max Dec; m·s⁻²). Results: Analysis of variance found differences between matches and training in WCSmean for TD, HSRD, SD, and Max Dec in all positions (p  .275). Fullbacks displayed differences between match and training in Max Acc (moderate ESs; p  .05). Main effects of playing status were discovered for all metrics except Max Dec (p  .124). Analysis showed differences between long- and congested-period for A+D and Dec (large ESs; p ≤ .05). Conclusions: Findings provide more insights into short peak intensity demands of soccer showing that the maximum high velocity action of acceleration and deceleration is not being replicated in training. Nonstarters lack maximum intensity exposure in matches (WCSₚₑₐₖ) increasing the gap between training and competition even higher during congested fixture periods

Water vapor on supergiants. The 12 micron TEXES spectra of mu Cephei

Several recent papers have argued for warm, semi-detached, molecular layers surrounding red giant and supergiant stars, a concept known as a MOLsphere. Spectroscopic and interferometric analyses have often corroborated this general picture. Here, we present high-resolution spectroscopic data of pure rotational lines of water vapor at 12 microns for the supergiant mu Cephei. This star has often been used to test the concept of molecular layers around supergiants. Given the prediction of an isothermal, optically thick water-vapor layer in Local Thermodynamic Equilibrium around the star (MOLsphere), we expected the 12 micron lines to be in emission or at least in absorption but filled in by emission from the molecular layer around the star. Our data, however, show the contrary; we find definite absorption. Thus, our data do not easily fit into the suggested isothermal MOLsphere scenario. The 12 micron lines, therefore, put new, strong constraints on the MOLsphere concept and on the nature of water seen in signatures across the spectra of early M supergiants. We also find that the absorption is even stronger than that calculated from a standard, spherically symmetric model photosphere without any surrounding layers. A cool model photosphere, representing cool outer layers is, however, able to reproduce the lines, but this model does not account for water vapor emission at 6 microns. Thus, a unified model for water vapor on mu Cephei appears to be lacking. It does seem necessary to model the underlying photospheres of these supergiants in their whole complexity. The strong water vapor lines clearly reveal inadequacies of classical model atmospheres.Comment: Accepted for publication in the Astrophysical Journa

Upper critical field for electrons in two-dimensional lattice

We address a problem of the upper critical field in a lattice described by a two-dimensional tight-binding model with the on-site pairing. We develop a finite-system-approach which enables investigation of magnetic and superconducting properties of electrons on clusters, consisting of a few thousand sites. We discuss how the quasiparticle density of states changes with the applied external magnetic field and present the temperature dependence of the upper critical field. We also briefly discuss possible extension of the model to account for the properties of high-temperature superconductors.Comment: 4 pages, 3 postscript figures, revte

Cross Validation of a Figure Skating Blade Instrumented to Measure Figure Skating Impact

Please refer to the pdf version of the abstract located adjacent to the title

A cross-discipline approach to healthcare needs

With rapid advancements in technology and growing demand for better healthcare, hospitals are struggling to find a balance between providing the best possible care and maintaining a responsible budget. This issue is especially evident in small hospitals lacking resources and infrastructure to keep up with modern technology. The Engineering for Modern Healthcare Creative Inquiry is a collaboration between Industrial Engineering and Bioengineering students. Our goal is to help small hospitals to develop efficient, cost-effective solutions to their needs. Currently, we are working with hospitals in South Carolina and Virginia to explore these solutions. We are interviewing clinicians, nurses, and other staff members to better understand current practices and identify improvement opportunities. Our initial focus will be on inventory management and sterile processing. Utilizing both departments\u27 expertise, we will develop a comprehensive solution to this complicated need