A deep, narrow J-band search for proto-galactic Lyman Alpha emission at redshifts z~9

We present a deep, narrow J-band search for proto--galactic Lyman Alpha emission at redshifts z~9. We combine an exceptionally deep image of the Hubble Deep Field South, obtained using a narrow band filter centred on the wavelength 1.187 microns using the VLT/ISAAC facility, with existing deep, broad band images covering optical to near infrared wavelengths. We search for z~9 Lyman Alpha emitting galaxies displaying a significant narrow band excess relative to the Js-band that are undetected at optical wavelengths. We detect no sources consistent with this criterion to the 90% point source flux limit of the NB image, F_{NB} = 3.28 x 10^{-18} ergs/s/cm2. The survey selection function indicates that we have sampled a volume of approximately 340 h^{-3} Mpc^3 to a Lyman Alpha emission luminosity of 10^{43} h^{-2} ergs/s. We conclude by considering the potential implications for the physics of the high--redshift universe.Comment: 11 pages, accepted MNRAS. Please note that the automatic postscript generation may result in a corrupted postscript file. Please use ftp://astroftp.phys.uvic.ca/pub/jwillis/jwillis_zen1.ps.gz to obtain an uncorrupted versio

Brief, Aerobic-surge Exercises for Effective Weight Loss: a Randomized, Controlled Trial

Background: Obesity is a growing disease and a consistently effective protocol is needed to reduce this epidemic. The purpose of this study was to determine if a frequent, brief (2-minute) high intensity aerobic exercise (≥75% max HR) was effective in reducing subjects’ weight (BMI) and girth sizes. Methods: A randomized, controlled trial lasting 60 days was conducted at three sites and forty-six subjects completed this study (mean age 39 ± 8 and BMI 32 ±2). The Experimental group was shown how to make movements such as riding a stationary bicycle or lifting dumbbells into an ‘Aerobic-surge’ exercise at or above 75% of calculated maximum heart rate. Control subjects were simply told to “exercise more.” No dietary changes were made for either group. The dependent variables were changes in weight and ‘body summation’ of 10 girth measurements. A 2x2 ANOVA was used to calculate differences. A post-hoc analysis of changes in BMI was also calculated. Results: There was a significant difference between groups (P<0.0001). The mean change of the groups were as follows: Experimental (N=23) mean reductions = -18.lbs and -18.7” vs. Control (N=23) mean changes = +1.3.lbs and +1.3.” Conclusion: The repeated, brief (2-minute) aerobic-surge exercise protocol, performed 4.2 times/day was effective in reducing subjects’ weight and body circumferences. Isolated tests of body composition showed that change were primarily in body fat. This could be a tool in reducing the obesity epidemic. The Aerobic-surge exercise was effective without a dietary changes. Retrospectively Registered Trial: ISRCTN 17326333

Hydromagnetic Taylor--Couette flow: wavy modes

We investigate magnetic Taylor--Couette flow in the presence of an imposed axial magnetic field. First we calculate nonlinear steady axisymmetric solutions and determine how their strength depends on the applied magnetic field. Then we perturb these solutions to find the critical Reynolds numbers for the appearance of wavy modes, and the related wavespeeds, at increasing magnetic field strength. We find that values of imposed magnetic field which alter only slightly the transition from circular--Couette flow to Taylor--vortex flow, can shift the transition from Taylor--vortex flow to wavy modes by a substantial amount. The results are compared against onset in the absence of a magnetic field.Comment: 12 pages, 8 figures. To appear in J. Fluid Mech. To appear in J. Fluid Mec

Experimental study of noise reduction for an unstiffened cylindrical model of an airplane fuselage

Noise reduction measurements were made for a simplified model of an airplane fuselage consisting of an unstiffened aluminum cylinder 0.5 m in diameter by 1.2 m long with a 1.6-mm-thick wall. Noise reduction was first measured with a reverberant field pink-noise load on the cylinder exterior. Next, noise reduction was measured by using a propeller to provide a more realistic noise load on the cylinder. Structural resonance frequencies and acoustic reverberation times for the cylinder interior volume were also measured. Comparison of data from the relatively simple test using reverberant-field noise with data from the more complex propeller-noise tests indicates some similarity in both the overall noise reduction and the spectral distribution. However, all of the test parameters investigated (propeller speed, blade pitch, and tip clearance) had some effect on the noise-reduction spectra. Thus, the amount of noise reduction achieved appears to be somewhat dependent upon the spectral and spatial characteristics of the flight conditions. Information is also presented on cyclinder resonance frequencies, damping, and characteristics of propeller-noise loads

Antisoiling technology: Theories of surface soiling and performance of antisoiling surface coatings

Physical examination of surfaces undergoing natural outdoor soiling suggests that soil matter accumulates in up to three distinct layers. The first layer involves strong chemical attachment or strong chemisorption of soil matter on the primary surface. The second layer is physical, consisting of a highly organized arrangement of soil creating a gradation in surface energy from a high associated with the energetic first layer to the lowest possible state on the outer surfce of the second layer. The lowest possible energy state is dictated by the physical nature of the regional atmospheric soiling materials. These first two layers are resistant to removal by rain. The third layer constitutes a settling of loose soil matter, accumulating in dry periods and being removed during rainy periods. Theories and evidence suggest that surfaces that should be naturally resistant to the formation of the first two-resistant layers should be hard, smooth, hydrophobic, free of first-period elements, and have the lowest possible surface energy. These characteristics, evolving as requirements for low-soiling surfaces, suggest that surfaces or surface coatings should be of fluorocarbon chemistry. Evidence for the three-soil-layer concept, and data on the positive performance of candidate fluorocarbon coatings on glass and transparent plastic films after 28 months of outdoor exposure, are presented

Ground-based photometry of comets in the spectral interval 3000 to 3500 angstrom

Abundances and production rates of CN, C3, and C2 for fifteen comets were determined and the variation of these parameters with helicentric distance for two comets were monitored. While these measurements provide much information about the similarities and differences among comets, only a small fraction of the total material in any of the comets observed was sampled

A public relations guide for military commanders

Thesis (M.S.)--Boston Universit