Emerging patterns of species richness, diversity, population density, and distribution in the skates (Rajidae) of Alaska

Six years of bottom-trawl survey data, including over 6000 trawls covering over 200 km2 of bottom area throughout Alaska’s subarctic marine waters, were analyzed for patterns in species richness, diversity, density, and distribution of skates. The Bering Sea continental shelf and slope, Aleutian Islands, and Gulf of Alaska regions were stratified by geographic subregion and depth. Species richness and relative density of skates increased with depth to the shelf break in all regions. The Bering Sea shelf was dominated by the Alaska skate (Bathyraja parmifera), but species richness and diversity were low. On the Bering Sea slope, richness and diversity were higher in the shallow stratum, and relative density appeared higher in subregions dominated by canyons. In the Aleutian Islands and Gulf of Alaska, species richness and relative density were generally highest in the deepest depth strata. The data and distribution maps presented here are based on species-level data collected throughout the marine waters of Alaska, and this article represents the most comprehensive summary of the skate fauna of the region published to date

Surface Geology of the Palo Duro and Dalhart Basins, Area, Texas

The Texas Panhandle includes primarily two physiographic provinces: the High Plains which overlies the Dalhart and most of the Palo Duro Basin and the Rolling Plains characterizing the eastern part of the Palo Duro Basin area. These two provinces are separated by the Caprock Escarpment, a prominent erosional feature along which relief locally exceeds 1,500 ft (500 m). The High Plains is developed on the Tertiary Ogallala Formation and forms a broad, flat plain having a regional slope to the southeast of 8 to 10 ft per mile. The Rolling Plains were formed by erosion of the Ogallala Formation which exposed the varying lithologies of the underlying Permian and Triassic age units. The easterly flowing Canadian River divides the High Plains into two sections: the Northern High Plains overlying the Dalhart Basin, and the Southern High Plains, or Llano Estacada, overlying the Palo Duro Basin. Prominent escarpments bounding the High Plains on the west, east, and along the Canadian River Valley are the result of Quaternary erosion. These escarpments provide most of the Tertiary and Triassic rock exposures. The flat surface of the High Plains is interrupted by numerous playas, dunes, and a surface drainage system composed of linear draws or channels. Pleistocene strata are exposed in some stream-cut channels and large playas on the High Plains surface. With the exception of the Canadian River drainage system and minor streams, major portions of the High Plains surface are without external drainage.Bureau of Economic Geolog

Use of Kriging to Estimate the Wolfcampian and San Andres Potentiometric Surfaces, Palo Duro Basin, Texas Panhandle

Kriging is a statistical method historically used to estimate mineral reserves and more recently applied to estimate spatially-distributed or regionalized variables in hydrologic studies, such as ground-water fluid potential or transmissivity. In estimating these regionalized variables, kriging serves two main purposes. Firstly, it can generate a contour map of the variable with an associated measure of error. Secondly, it can optimize the location of additional samples, particularly valuable in acquiring data for ground-water potential in deep formations, which often involves drilling expensive wells. Kriging has been previously employed to estimate water elevation in studies such as those conducted at the Department of Energy Hanford Reservation in the Pasco Basin, Washington (Doctor, 1979), and in a study of the multilayer aquifer system underlying Venice, Italy (Volpi and Gambolati, 1979). In both cases, actual water level measurements were utilized. This report discusses the use of kriging methods by The University of Texas, Bureau of Economic Geology (UT/BEG), in the context of nuclear waste isolation feasibility studies in the Palo Duro Basin, funded by the Department of Energy under contract DE-AC97-80ET46615. Kriging has been employed by UT/BEG to estimate the ground-water potentiometric surfaces of the permeable San Andres cycle four dolomite and the Wolfcampian aquifer. The San Andres Formation study utilized water level measurements and drill-stem-test (DST) pressures. Kriging was applied to minimize the variation of the DST data and reveal the regional potentiometric surface. The Wolfcamp study relied solely on DST pressures, with kriging employed to model the variation in the data and generate a contoured map of the potentiometric surface. The kriging techniques employed by the Bureau of Economic Geology involve three steps: (1) variogram analysis, (2) kriging, and (3) contouring krige block estimates. Computer programs used for calculating the empirical variogram statistics, krige block estimates, and krige block variances were obtained from Dr. Young C. Kim and are detailed in Knudsen and Kim, 1978. For a comprehensive understanding of regionalized variables theory and kriging, please refer to Knudsen and Kim, 1978. A brief overview of the techniques used at the Bureau follows.Bureau of Economic Geolog

Response to a rabies epidemic in Bali, Indonesia

Emergency vaccinations and culling failed to contain an outbreak of rabies in Bali, Indonesia, during 2008–2009. Subsequent island-wide mass vaccination (reaching 70% coverage, >200,000 dogs) led to substantial declines in rabies incidence and spread. However, the incidence of dog bites remains high, and repeat campaigns are necessary to eliminate rabies in Bali

Bypass to Turbulence in Hydrodynamic Accretion Disks: An Eigenvalue Approach

Cold accretion disks such as those in star-forming systems, quiescent cataclysmic variables, and some active galactic nuclei, are expected to have neutral gas which does not couple well to magnetic fields. The turbulent viscosity in such disks must be hydrodynamic in origin, not magnetohydrodynamic. We investigate the growth of hydrodynamic perturbations in a linear shear flow sandwiched between two parallel walls. The unperturbed flow is similar to plane Couette flow but with a Coriolis force included. Although there are no exponentially growing eigenmodes in this system, nevertheless, because of the non-normal nature of the eigenmodes, it is possible to have a large transient growth in the energy of perturbations. For a constant angular momentum disk, we find that the perturbation with maximum growth has a wave-vector in the vertical direction. The energy grows by more than a factor of 100 for a Reynolds number R=300 and more than a factor of 1000 for R=1000. Turbulence can be easily excited in such a disk, as found in previous numerical simulations. For a Keplerian disk, on the other hand, similar vertical perturbations grow by no more than a factor of 4, explaining why the same simulations did not find turbulence in this system. However, certain other two-dimensional perturbations with no vertical structure do exhibit modest growth. For the optimum two-dimensional perturbation, the energy grows by a factor of ~100 for R~10^4.5 and by a factor of 1000 for R~10^6. It is conceivable that these two-dimensional disturbances might lead to self-sustained turbulence. The Reynolds numbers of cold astrophysical disks are much larger even than 10^6, therefore, hydrodynamic turbulence may be possible in disks.Comment: 39 pages including 9 figures; Final version to appear in The Astrophysical Journa

Rubisco catalytic properties of wild and domesticated relatives provide scope for improving wheat photosynthesis

Rubisco is a major target for improving crop photosynthesis and yield, yet natural diversity in catalytic properties of this enzyme is poorly understood. Rubisco from 25 genotypes of the Triticeae tribe, including wild relatives of bread wheat (Triticum aestivum), were surveyed to identify superior enzymes for improving photosynthesis in this crop. In vitro Rubisco carboxylation velocity (V c), Michaelis–Menten constants for CO2 (K c) and O2 (K o) and specificity factor (S c/o) were measured at 25 and 35 °C. V c and K c correlated positively, while V c and S c/o were inversely related. Rubisco large subunit genes (rbcL) were sequenced, and predicted corresponding amino acid differences analysed in relation to the corresponding catalytic properties. The effect of replacing native wheat Rubisco with counterparts from closely related species was analysed by modelling the response of photosynthesis to varying CO2 concentrations. The model predicted that two Rubisco enzymes would increase photosynthetic performance at 25 °C while only one of these also increased photosynthesis at 35 °C. Thus, under otherwise identical conditions, catalytic variation in the Rubiscos analysed is predicted to improve photosynthetic rates at physiological CO2 concentrations. Naturally occurring Rubiscos with superior properties amongst the Triticeae tribe can be exploited to improve wheat photosynthesis and crop productivity

Work in Progress -- Does a Technology-Rich Transportation Engineering Experiences Increase Interest in Civil Engineering

This paper examines whether a technology-rich transportation engineering experience generates interest among college freshman students towards transportation related degrees and careers, specifically, whether it increases interest in civil engineering. Louisiana Tech’s first-year engineering experience provides relevant, project-focused education for over 500 students each year and an opportunity to introduce transportation-related projects. The six semester-hour, three-course sequence, called “Living with the Lab,” boosts experiential learning through student ownership of inexpensive laboratory equipment. In one section of the Living with the Lab course, a transportation engineer visited the class and the students were led through a technology-rich transportation engineering activity. They used an ultrasonic distance sensor to build a device to measure traffic speed. At the end of the term, students were asked to rate their interest level in 22 fields of study (one of which is civil engineering) from “not at all interested” (1) to “extremely interested” (7). Asking for interest level in each field provides finer resolution than only looking at which major a student selects. Interest levels in civil engineering of the section that did the transportation engineering activity were slightly higher than those of the other sections, but the difference was not statistically significant