Shear Flows of Rapidly Flowing Granular Materials

Shear flows of granular materials are studied in an open channel. The wall shear is calculated from an open channel momentum equation which includes the density variations in the flow. An experimental technique was developed that allowed the measurement of the average density of the flow at different longitudinal locations in the channel. Two sizes of glass beads are examined and results show the variations in the wall shear as a function of various dimensionless parameters

A Flight Evaluation of a VTOL Jet Transport Under Visual and Simulated Instrument Conditions

Transition, approach, and vertical landing tests for VTOL transport in terminal are

Are infestations of Cymomelanodactylus killing Acropora cytherea in the Chagos archipelago?

Associations between branching corals and infaunal crabs are well known, mostly due to the beneficial effects of Trapezia and Tetralia crabs in protecting host corals from crown-of-thorns starfish (e.g., Pratchett et al. 2000) and/or sedimentation (Stewart et al. 2006). These crabs are obligate associates of live corals and highly prevalent across suitable coral hosts, with 1–2 individuals per colony (Patton 1994). Cymo melanodactylus (Fig. 1) are also prevalent in branching corals, mostly Acropora, and are known to feed on live coral tissue, but are generally found in low abundance (<3 per colony) and do not significantly affect their host corals (e.g., Patton 1994). In the Chagos archipelago, however, infestations of Cymo melanodactylus were found on recently dead and dying colonies of Acropora cytherea

Fundamental Magnetic Properties and Structural Implications for Nanocrystalline Fe-Ti-N Thin Films

The magnetization (M) as a function of temperature (T) from 2 to 300 K and in-plane field (H) up to 1 kOe, room temperature easy and hard direction in-plane field hysteresis loops for fields between -100 and +100 Oe, and 10 GHz ferromagnetic resonance (FMR) profiles have been measured for a series of soft-magnetic nano-crystalline 50 nm thick Fe-Ti-N films made by magnetron sputtering in an in-plane field. The nominal titanium concentration was 3 at. % and the nitrogen concentrations (xN) ranged from zero to 12.7 at. %. The saturation magnetization (Ms) vs. T data and the extracted exchange parameters as a function of xN are consistent with a lattice expansion due to the addition of interstitial nitrogen in the body-centered-cubic (bcc) lattice and a structural transition to body-centered-tetragonal (bct) in the 6-8 at. % nitrogen range. The hysteresis loop and FMR data show a consistent picture of the changes in both the uniaxial and cubic anisotropy as a function of xN. Films with xN > 1.9 at. % show an overall uniaxial anisotropy, with an anisotropy field parameter Hu that increases with xN. The corresponding dispersion averaged uniaxial anisotropy energy density parameter = HuMs/2 is a linear function of xN, with a rate of increase of 950 erg/cm3 per at. % nitrogen. The estimated uniaxial anisotropy energy per nitrogen atom is 30 J/mol, a value consistent with other systems. For xN below 6 at. %, the scaling of coercive force Hc data with the sixth power of the grain size D indicate a grain averaged effective cubic anisotropy energy density parameter that is about an order of magnitude smaller that the nominal K1 values for iron, and give a quantitative vs. D response that matches predictions for exchange coupled random grains with cubic anisotropy.Comment: 13 pages, 7 figure

Stream network analysis and geomorphic flood plain mapping from orbital and suborbital remote sensing imagery application to flood hazard studies in central Texas

The author has identified the following significant results. Development of a quantitative hydrogeomorphic approach to flood hazard evaluation was hindered by (1) problems of resolution and definition of the morphometric parameters which have hydrologic significance, and (2) mechanical difficulties in creating the necessary volume of data for meaningful analysis. Measures of network resolution such as drainage density and basin Shreve magnitude indicated that large scale topographic maps offered greater resolution than small scale suborbital imagery and orbital imagery. The disparity in network resolution capabilities between orbital and suborbital imagery formats depends on factors such as rock type, vegetation, and land use. The problem of morphometric data analysis was approached by developing a computer-assisted method for network analysis. The system allows rapid identification of network properties which can then be related to measures of flood response

A Widespread, Clumpy Starburst in the Isolated Ongoing Dwarf Galaxy Merger dm1647+21

Interactions between pairs of isolated dwarf galaxies provide a critical window into low-mass hierarchical, gas-dominated galaxy assembly and the buildup of stellar mass in low-metallicity systems. We present the first VLT/MUSE optical IFU observations of the interacting dwarf pair dm1647+21, selected from the TiNy Titans survey. The H$\alpha$ emission is widespread and corresponds to a total unobscured star formation rate (SFR) of 0.44 M$_{\odot}$ yr$^{-1}$, 2.7 times higher than the SFR inferred from SDSS data. The implied specific SFR (sSFR) for the system is elevated by more than an order of magnitude above non-interacting dwarfs in the same mass range. This increase is dominated by the lower-mass galaxy, which has a sSFR enhancement of $>$ 50. Examining the spatially-resolved maps of classic optical line diagnostics, we find the ISM excitation can be fully explained by star formation. The velocity field of the ionized gas is not consistent with simple rotation. Dynamical simulations indicate that the irregular velocity field and the stellar structure is consistent with the identification of this system as an ongoing interaction between two dwarf galaxies. The widespread, clumpy enhancements in star formation in this system point to important differences in the effect of mergers on dwarf galaxies, compared to massive galaxies: rather than the funneling of gas to the nucleus and giving rise to a nuclear starburst, starbursts in low-mass galaxy mergers may be triggered by large-scale ISM compression, and thus be more distributed.Comment: Accepted for publication in ApJ. 11 pages, 5 figures, 1 table. Figures slightly degraded to meet arXiv size restrictions. For more information about TiNy Titans see https://lavinia.as.arizona.edu/~tinytitans

New Techniques for Relating Dynamically Close Galaxy Pairs to Merger and Accretion Rates : Application to the SSRS2 Redshift Survey

We introduce two new pair statistics, which relate close galaxy pairs to the merger and accretion rates. We demonstrate the importance of correcting these (and other) pair statistics for selection effects related to sample depth and completeness. In particular, we highlight the severe bias that can result from the use of a flux-limited survey. The first statistic, denoted N_c, gives the number of companions per galaxy, within a specified range in absolute magnitude. N_c is directly related to the galaxy merger rate. The second statistic, called L_c, gives the total luminosity in companions, per galaxy. This quantity can be used to investigate the mass accretion rate. Both N_c and L_c are related to the galaxy correlation function and luminosity function in a straightforward manner. We outline techniques which account for various selection effects, and demonstrate the success of this approach using Monte Carlo simulations. If one assumes that clustering is independent of luminosity (which is appropriate for reasonable ranges in luminosity), then these statistics may be applied to flux-limited surveys. These techniques are applied to a sample of 5426 galaxies in the SSRS2 redshift survey. Using close dynamical pairs, we find N_c(-21<M_B<-18) = 0.0226+/-0.0052 and L_c(-21<M_B<-18) = 0.0216+/-0.0055 10^{10} h^2 L_sun at z=0.015. These are the first secure estimates of low-z close pair statistics. If N_c remains fixed with redshift, simple assumptions imply that ~ 6.6% of present day galaxies with -21<M_B<-18 have undergone mergers since z=1. When applied to redshift surveys of more distant galaxies, these techniques will yield the first robust estimates of evolution in the galaxy merger and accretion rates. [Abridged]Comment: 26 pages (including 10 postscript figures) plus 3 gif figures. Accepted for publication in ApJ. Paper (including full resolution images) also available at http://www.astro.utoronto.ca/~patton/ssrs2, along with associated pair classification experiment (clickable version of Figure 5

Baylisascaris procyonis in raccoons (Procyon lotor) in eastern Tennessee

Raccoon (Procyon lotor) carcasses (n=118) were collected from July through December 2007 throughout eastern Tennessee. Necropsies were performed, and Baylisascaris procyonis was collected from the gastrointestinal tract of infected carcasses. Prevalence rates were determined for the overall sample population, males and females, and adults and juveniles. The sample population had a B. procyonis prevalence of 12.7%. Males and females had a prevalence of 15% and 11%, respectively; prevalence in adults and juvenile was 13% and 12.6%, respectively. There were no significant differences in prevalence rates between the different groups. Baylisascaris procyonis is an ascarid infection of raccoons that can infect humans and over 100 species of other animals. The presence of infection in raccoons, paired with the expansion of human populations in eastern Tennessee, is likely to lead to increased interactions between humans and raccoons and therefore an increased risk of human and domestic animal exposure to B. procyonis