Conservation Assessment and Habitat Notes for Three Rare Alabama Crayfishes: Cambarus cracens, Cambarus scotti, and Cambarus unestami

Over seventy percent of the world\u27s freshwater crayfish species are found within the United States, and much of this diversity is concentrated in the southeastern United States. Yet many of these species remain understudied. Of particular interest is the conservation status of these understudied taxa. We conducted fieldwork in 2011 across northeastern Alabama and northwestern Georgia to review the occurrence, habitat, and in sonic cases, local population densities of three crayfish species (Cambarus scotti, C. unestami, and C. cracens) to determine current distributions in relation to historical surveys. All three species occur in flowing small to medium-sized streams with firm substrates of gravel, cobble, and bedrock. Two species (C. scotti and C. unestami) have stable populations, occurring at 79% and 90% of sites surveyed, respectively. In contrast, surveys for the third crayfish species (C. cracens) indicated a need for conservation action, with this species occurring at a single site

Micropillar compression testing of powders

An experimental design for microcompression on individual powder particles is proposed as a means of testing novel materials without the challenges associated with consolidation to produce bulk specimens. This framework is demonstrated on an amorphous tungsten alloy powder, and yields reproducible measurements of the yield strength (4.5 ± 0.3 GPa) and observations of the deformation mode (in this case, serrated flow by shear localization).United States. Defense Threat Reduction Agency (Grant HDTRA1-11-1-0062)American Society for Engineering Education. National Defense Science and Engineering Graduate Fellowshi

Distribution and Conservation Status of the Rusty Gravedigger, Cambarus miltus, a Poorly Known Gulf Coastal Crayfish

Cambarus (Lacunicambarus) miltus (Rusty Gravedigger Crayfi sh) is a primary burrowing crayfi sh known from a limited portion of the Gulf Coastal region of the United States. The lack of form I males in collections has in the past prevented specieslevel identifi cations and hampered conservation reviews. We conducted an intensive status survey for C. miltus during 2007 and 2008. Our results suggest that the species is much more widespread than previously known and that conservation attention is unwarranted. Preferred habitat for the species is ephemerally fl ooded and thinly wooded fl oodplains of small streams and swamps

Time-Accurate Unsteady Pressure Loads Simulated for the Space Launch System at Wind Tunnel Conditions

A transonic flow field about a Space Launch System (SLS) configuration was simulated with the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics (CFD) code at wind tunnel conditions. Unsteady, time-accurate computations were performed using second-order Delayed Detached Eddy Simulation (DDES) for up to 1.5 physical seconds. The surface pressure time history was collected at 619 locations, 169 of which matched locations on a 2.5 percent wind tunnel model that was tested in the 11 ft. x 11 ft. test section of the NASA Ames Research Center's Unitary Plan Wind Tunnel. Comparisons between computation and experiment showed that the peak surface pressure RMS level occurs behind the forward attach hardware, and good agreement for frequency and power was obtained in this region. Computational domain, grid resolution, and time step sensitivity studies were performed. These included an investigation of pseudo-time sub-iteration convergence. Using these sensitivity studies and experimental data comparisons, a set of best practices to date have been established for FUN3D simulations for SLS launch vehicle analysis. To the author's knowledge, this is the first time DDES has been used in a systematic approach and establish simulation time needed, to analyze unsteady pressure loads on a space launch vehicle such as the NASA SLS

Time Accurate Unsteady Pressure Loads Simulated for the Space Launch System at a Wind Tunnel Condition

Using the Fully Unstructured Three-Dimensional (FUN3D) computational fluid dynamics code, an unsteady, time-accurate flow field about a Space Launch System configuration was simulated at a transonic wind tunnel condition (Mach = 0.9). Delayed detached eddy simulation combined with Reynolds Averaged Naiver-Stokes and a Spallart-Almaras turbulence model were employed for the simulation. Second order accurate time evolution scheme was used to simulate the flow field, with a minimum of 0.2 seconds of simulated time to as much as 1.4 seconds. Data was collected at 480 pressure taps at locations, 139 of which matched a 3% wind tunnel model, tested in the Transonic Dynamic Tunnel (TDT) facility at NASA Langley Research Center. Comparisons between computation and experiment showed agreement within 5% in terms of location for peak RMS levels, and 20% for frequency and magnitude of power spectral densities. Grid resolution and time step sensitivity studies were performed to identify methods for improved accuracy comparisons to wind tunnel data. With limited computational resources, accurate trends for reduced vibratory loads on the vehicle were observed. Exploratory methods such as determining minimized computed errors based on CFL number and sub-iterations, as well as evaluating frequency content of the unsteady pressures and evaluation of oscillatory shock structures were used in this study to enhance computational efficiency and solution accuracy. These techniques enabled development of a set of best practices, for the evaluation of future flight vehicle designs in terms of vibratory loads

Spitzer observations of the Massive star forming complex S254-S258: structure and evolution

We present Spitzer-IRAC, NOAO 2.1meter-Flamingos, Keck-NIRC, and FCRAO-SEQUOIA observations of the massive star forming complex S254-S258, covering an area of 25x20 arc-minutes. Using a combination of the IRAC and NIR data, we identify and classify the young stellar objects (YSO) in the complex. We detect 510 sources with near or mid IR-excess, and we classify 87 Class I, and 165 Class II sources. The YSO are found in clusters surrounded by isolated YSO in a low-density distributed population. The ratio of clustered to total YSO is 0.8. We identify six new clusters in the complex. One of them, G192.63-00, is located around the ionizing star of the HII region S255. We hypothesize that the ionizing star of S255 was formed in this cluster. We also detect a southern component of the cluster in HII region S256. The cluster G192.54-0.15, located inside HII region S254 has a VLSR of 17 km/s with respect to the main cloud, and we conclude that it is located in the background of the complex. The structure of the molecular cloud is examined using 12CO and 13CO, as well as a near-IR extinction map. The main body of the molecular cloud has VLSR between 5 and 9 km/s. The arc-shaped structure of the molecular cloud, following the border of the HII regions, and the high column density in the border of the HII regions support the idea that the material has been swept up by the expansion of the HII regions.Comment: Accepted for publication in The Astrophysical Journa

Towards More Precise Survey Photometry for PanSTARRS and LSST: Measuring Directly the Optical Transmission Spectrum of the Atmosphere

Motivated by the recognition that variation in the optical transmission of the atmosphere is probably the main limitation to the precision of ground-based CCD measurements of celestial fluxes, we review the physical processes that attenuate the passage of light through the Earth's atmosphere. The next generation of astronomical surveys, such as PanSTARRS and LSST, will greatly benefit from dedicated apparatus to obtain atmospheric transmission data that can be associated with each survey image. We review and compare various approaches to this measurement problem, including photometry, spectroscopy, and LIDAR. In conjunction with careful measurements of instrumental throughput, atmospheric transmission measurements should allow next-generation imaging surveys to produce photometry of unprecedented precision. Our primary concerns are the real-time determination of aerosol scattering and absorption by water along the line of sight, both of which can vary over the course of a night's observations.Comment: 41 pages, 14 figures. Accepted PAS

Toward 1% Photometry: End-to-end Calibration of Astronomical Telescopes and Detectors

We review the systematic uncertainties that have plagued attempts to obtain high precision and high accuracy from ground-based photometric measurements using CCDs. We identify two main challenges in breaking through the 1% precision barrier: 1) fully characterizing atmospheric transmission, along the instrument's line of sight, and 2) properly identifying, measuring and removing instrumental artifacts. We discuss approximations and limitations inherent in the present methodology, and we estimate their contributions to systematic photometric uncertainties. We propose an alternative conceptual scheme for the relative calibration of astronomical apparatus: the availability of calibrated detectors whose relative spectral sensitivity is known to better than one part in $10^3$ opens up the possibility of in situ relative throughput measurements, normalized to a precision calibrated detector, using a stable but uncalibrated narrowband light source. An implementation scheme is outlined, which exploits the availability of tunable lasers to map out the relative wavelength response of an imaging system, using a flatfield screen and a calibrated reference photodiode. The merits and limitations of this scheme are discussed. In tandem with careful measurements of atmospheric transmission, this approach could potentially lead to reliable ground-based photometry with fractional uncertainties below the percent level.Comment: 25 pages, no figures. To be published in Ap

Metabolic and Bactericidal Effects of Targeted Suppression of NadD and NadE Enzymes in Mycobacteria

ABSTRACT Mycobacterium tuberculosis remains a major cause of death due to the lack of treatment accessibility, HIV coinfection, and drug resistance. Development of new drugs targeting previously unexplored pathways is essential to shorten treatment time and eliminate persistent M. tuberculosis. A promising biochemical pathway which may be targeted to kill both replicating and nonreplicating M. tuberculosis is the biosynthesis of NAD(H), an essential cofactor in multiple reactions crucial for respiration, redox balance, and biosynthesis of major building blocks. NaMN adenylyltransferase (NadD) and NAD synthetase (NadE), the key enzymes of NAD biosynthesis, were selected as promising candidate drug targets for M. tuberculosis. Here we report for the first time kinetic characterization of the recombinant purified NadD enzyme, setting the stage for its structural analysis and inhibitor development. A protein knockdown approach was applied to validate bothNadD and NadE as target enzymes. Induced degradation of either target enzyme showed a strong bactericidal effect which coincided with anticipated changes in relative levels of NaMN and NaAD intermediates (substrates of NadD and NadE, respectively) and ultimate depletion of the NAD(H) pool. A metabolic catastrophe predicted as a likely result of NAD(H) deprivation of cellular metabolism was confirmed by 13C biosynthetic labeling followed by gas chromatography-mass spectrometry (GC-MS) analysis. A sharp suppression of metabolic flux was observed in multiple NAD(P)(H)-dependent pathways, including synthesis of many amino acids (serine, proline, aromatic amino acids) and fatty acids. Overall, these results provide strong validation of the essential NAD biosynthetic enzymes, NadD and NadE, as antimycobacterial drug targets

Sketch-n-Sketch: Output-Directed Programming for SVG

For creative tasks, programmers face a choice: Use a GUI and sacrifice flexibility, or write code and sacrifice ergonomics? To obtain both flexibility and ease of use, a number of systems have explored a workflow that we call output-directed programming. In this paradigm, direct manipulation of the program's graphical output corresponds to writing code in a general-purpose programming language, and edits not possible with the mouse can still be enacted through ordinary text edits to the program. Such capabilities provide hope for integrating graphical user interfaces into what are currently text-centric programming environments. To further advance this vision, we present a variety of new output-directed techniques that extend the expressive power of Sketch-n-Sketch, an output-directed programming system for creating programs that generate vector graphics. To enable output-directed interaction at more stages of program construction, we expose intermediate execution products for manipulation and we present a mechanism for contextual drawing. Looking forward to output-directed programming beyond vector graphics, we also offer generic refactorings through the GUI, and our techniques employ a domain-agnostic provenance tracing scheme. To demonstrate the improved expressiveness, we implement a dozen new parametric designs in Sketch-n-Sketch without text-based edits. Among these is the first demonstration of building a recursive function in an output-directed programming setting.Comment: UIST 2019 Paper + Appendi