840 research outputs found
Development of a conservation action plan for the eastern hellbender (Cryptobranchus alleganiensis alleganiensis) in West Virginia
The Eastern hellbender (Cryptobranchus alleganiensis alleganiensis ) is the largest salamander in North America growing to 75 centimeters in length. This fully aquatic species is an indicator of good stream and river quality and has been considered to be in decline or rare throughout its range. This study focused on the current distribution of the Eastern hellbender at sites of historic occurrence in West Virginia in order to determine the species\u27 current range and factors impacting its distribution in order to facilitate planned reintroductions and translocations of hellbenders reared in human care. The success of the reintroduction and translocation efforts were also a key focus of this study to determine if the release of individuals raised in human care could contribute to the conservation of this species in West Virginia.;Results of this study have indicated that hellbenders were only detected at 12 of 23 (52%) surveyed sites of historic occurrence, and the habitat variables most strongly associated with the presence of this species at historic sites was the presence of forested landscape within the watershed and increased dissolved oxygen concentration within streams and rivers.;Key data from diet intake studies showed that 84% of hellbenders collected in West Virginia during periods of feeding had consumed crayfish with fish species being the second most frequently observed item consumed. In addition, no (39 of 39) hellbenders captured from July 8th - August 29th in West Virginia had any food items present in their stomach during surveys. The greatest factor associated with the lack of prey consumption was water temperatures in excess of 23°C. These findings were confirmed with individuals in human care with individuals maintained at these temperatures not eating and losing an average of 15.33 grams during the 86 day trial period.;Finally, we created predictive models based on sites of hellbender presence during our surveys to identify high probability of occurrence sites for translocation of head-started hellbenders. We then released 14 individuals at a reintroduction site where head-started hellbender eggs were collected as well as 15 individuals at a translocation site that was previously occupied by hellbenders. Survival rates through 6 months of tracking during this study did not differ statistically between sites. Movement and home range were greater at the reintroduction site than at the translocation site, and stream bank shelters were used more frequently than stone shelters at the reintroduction site than at the translocation site. Increased movement and alternative shelter use are believed to be due to reduced shelter availability due to fewer boulders and the presence of adult hellbenders at the reintroduction site as opposed to conditions at the translocation site. Future hellbender conservation efforts in West Virginia should include preservation of forest habitat near current hellbender populations and surveillance of historic sites based upon predictive model results. Reintroductions and translocations of head-started juveniles or sub-adults should be conducted at sites of greatest predicted occurrence with long-term monitoring for detection of reproductively sustainable populations
Ne II Observations of Gas Motions in Compact and Ultracompact H II Regions
We present high spatial and spectral resolution observations of 16 Galactic compact and ultracompact H II regions in the [Ne II] 12.8 mu m fine-structure line. The small thermal width of the neon line and the high dynamic range of the maps provide an unprecedented view of the kinematics of compact and ultracompact H II regions. These observations solidify an emerging picture of the structure of ultracompact H II regions suggested in our earlier studies of G29.96-0.02 and Mon R2 IRS 1; systematic surface flows, rather than turbulence or bulk expansion, dominate the gas motions in the H II regions. The observations show that almost all of the sources have significant (5-20 km s(-1)) velocity gradients and that most of the sources are limb-brightened. In many cases, the velocity pattern implies tangential flow along a dense shell of ionized gas. None of the observed sources clearly fits into the categories of filled expanding spheres, expanding shells, filled blister flows, or cometary H II regions formed by rapidly moving stars. Instead, the kinematics and morphologies of most of the sources lead to a picture of H II regions confined to the edges of cavities created by stellar wind ram pressure and flowing along the cavity surfaces. In sources where the radio continuum and [Ne II] morphologies agree, the majority of the ionic emission is blueshifted relative to nearby molecular gas. This is consistent with sources lying on the near side of their natal clouds being less affected by extinction and with gas motions being predominantly outward, as is expected for pressure-driven flows.NSF AST-0607312, NSF-0708074SOFIA USRA8500-98-008NYSTAR Faculty Development ProgramNASA NNG 04-GG92G, CAN-NCC5-679Lunar and Planetary InstituteAstronom
TEXES Observations of M Supergiants: Dynamics and Thermodynamics of Wind Acceleration
We have detected [Fe II] 17.94 um and 24.52 um emission from a sample of M
supergiants using TEXES on the IRTF. These low opacity emission lines are
resolved at R = 50, 000 and provide new diagnostics of the dynamics and
thermodynamics of the stellar wind acceleration zone. The [Fe II] lines, from
the first excited term, are sensitive to the warm plasma where energy is
deposited into the extended atmosphere to form the chromosphere and wind
outflow. These diagnostics complement previous KAO and ISO observations which
were sensitive to the cooler and more extended circumstellar envelopes. The
turbulent velocities, Vturb is about 12 to 13 km/s, observed in the [Fe II]
forbidden lines are found to be a common property of our sample, and are less
than that derived from the hotter chromospheric C II] 2325 Angstrom lines
observed in alpha Ori, where Vturb is about 17 to 19 km/s. For the first time,
we have dynamically resolved the motions of the dominant cool atmospheric
component discovered in alpha Ori from multi-wavelength radio interferometry by
Lim et al. (1998). Surprisingly, the emission centroids are quite Gaussian and
at rest with respect to the M supergiants. These constraints combined with
model calculations of the infrared emission line fluxes for alpha Ori imply
that the warm material has a low outflow velocity and is located close to the
star. We have also detected narrow [Fe I] 24.04 um emission that confirms that
Fe II is the dominant ionization state in alpha Ori's extended atmosphere.Comment: 79 pages including 10 figures and 2 appendices. Accepted by Ap
Hdo And SO2 Thermal Mapping On Venus: Evidence For Strong SO2 Variability
We have been using the TEXES high-resolution imaging spectrometer at the NASA Infrared Telescope Facility to map sulfur dioxide and deuterated water over the disk of Venus. Observations took place on January 10-12, 2012. The diameter of Venus was 13 arcsec, with an illumination factor of 80%. Data were recorded in the 1344-1370 cm(-1) range (around 7.35 mu m) with a spectral resolving power of 80 000 and a spatial resolution of about 1.5 arcsec. In this spectral range, the emission of Venus comes from above the cloud top (z = 60-80 km). Four HDO lines and tens of SO2 lines have been identified in our spectra. Mixing ratios have been estimated from HDO/CO2 and SO2/CO2 line depth ratios, using weak neighboring transitions of comparable depths. The HDO maps, recorded on Jan. 10 and Jan. 12, are globally uniform with no significant variation between the two dates. A slight enhancement of the HDO mixing ratio toward the limb might be interpreted as a possible increase of the D/H ratio with height above the cloud level. The mean H2O mixing ratio is found to be 1.5 +/-0.75 ppm, assuming a D/H ratio of 0.0312 (i.e. 200 times the terrestrial value) over the cloud deck. The SO2 maps, recorded each night from Jan. 10 to Jan. 12, show strong variations over the disk of Venus, by a factor as high as 5 to 10. In addition, the position of the maximum SO2 mixing ratio strongly varies on a timescale of 24 h. The maximum SO2 mixing ratio ranges between 75 +/-25 ppb and 125 +/-50 ppb between Jan. 10 and Jan. 12. The high variability of sulfur dioxide is probably a consequence of its very short photochemical lifetime.NASA NNX-08AE38A, NNX08AW33G S03NSF AST-0607312, AST-0708074Astronom
Rocket Plume Scaling for Orion Wind Tunnel Testing
A wind tunnel test program was undertaken to assess the jet interaction effects caused by the various solid rocket motors used on the Orion Launch Abort Vehicle (LAV). These interactions of the external flowfield and the various rocket plumes can cause localized aerodynamic disturbances yielding significant and highly non-linear control amplifications and attenuations. This paper discusses the scaling methodologies used to model the flight plumes in the wind tunnel using cold air as the simulant gas. Comparisons of predicted flight, predicted wind tunnel, and measured wind tunnel forces-and-moments and plume flowfields are made to assess the effectiveness of the selected scaling methodologies
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HDO And SO2 Thermal Mapping On Venus II. The So2 Spatial Distribution Above And Within The Clouds
Sulfur dioxide and water vapor, two key species of Venus photochemistry, are known to exhibit significant spatial and temporal variations above the cloud top. In particular, ground-based thermal imaging spectroscopy at high spectral resolution, achieved on Venus in January 2012, has shown evidence for strong SO2 variations on timescales shorter than a day. We have continued our observing campaign using the TEXES high-resolution imaging spectrometer at the NASA InfraRed Telescope Facility to map sulfur dioxide over the disk of Venus at two different wavelengths, 7 mu m (already used in the previous study) and 19 mu m. The 7 mu m radiation probes the top of the H2SO4 cloud, while the 19 mu m radiation probes a few kilometers below within the cloud. Observations took place on October 4 and 5, 2012. Both HDO and SO2 lines are identified in our 7-mu m spectra and SO2 is also easily identified at 19 mu m. The CO2 lines at 7 and 19 mu m are used to infer the thermal structure. An isothermal/inversion layer is present at high latitudes (above 60 N and S) in the polar collars, which was not detected in October 2012. The enhancement of the polar collar in October 2012 is probably due to the fact that the morning terminator is observed, while the January data probed the evening terminator. As observed in our previous run, the HDO map is relatively uniform over the disk of Venus, with a mean mixing ratio of about 1 ppm. In contrast, the SO2 maps at 19 mu m show intensity variations by a factor of about 2 over the disk within the cloud, less patchy than observed at the cloud top at 7 mu m. In addition, the SO2 maps seem to indicate significant temporal changes within an hour. There is evidence for a cutoff in the SO2 vertical distribution above the cloud top, also previously observed by SPICAV/SOIR aboard Venus Express and predicted by photochemical models.NASA NNX-08AE38AIRTF AST-0607312, AST-0708074Astronom
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