630 research outputs found

    Caddisflies (Trichoptera) of Wildcat Creek, Pickens County, South Carolina

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    Sixty-two species of caddisflies (Trichoptera) were identified from collections make from Wildcat Creek over a period of 33 years. A new distributional record for South Carolina was obtained for Diplectrona metaqui. Eight species, Polycentropus carlsoni, Wormaldia thyria, Neotrichia collata, Stactobiella delira, Neophylax atlanta, Goera fuscula, Pseudogoera singularis, and Agarodes griseus, are considered to be threatened in South Carolina

    Scientific Standards and the Regulation of Genetically Modified Insects

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    Experimental releases of genetically modified (GM) insects are reportedly being evaluated in various countries, including Brazil, the Cayman Islands (United Kingdom), France, Guatemala, India, Malaysia, Mexico, Panama, Philippines, Singapore, Thailand, the United States of America, and Vietnam. GM mosquitoes (Aedes aegypti) have already been released for field trials into inhabited areas in the Cayman Islands (2009–?), Malaysia (2010–2011), and Brazil (2011–2012). Here, we assess the regulatory process in the first three countries permitting releases (Malaysia, US, and the Cayman Islands) in terms of pre-release transparency and scientific quality. We find that, despite 14 US government–funded field trials over the last 9 years (on a moth pest of cotton), there has been no scientific publication of experimental data, and in only two instances have permit applications been published. The world's first environmental impact statement (EIS) on GM insects, produced by US authorities in 2008, is found to be scientifically deficient on the basis that (1) most consideration of environmental risk is too generic to be scientifically meaningful; (2) it relies on unpublished data to establish central scientific points; and (3) of the approximately 170 scientific publications cited, the endorsement of the majority of novel transgenic approaches is based on just two laboratory studies in only one of the four species covered by the document. We find that it is not possible to determine from documents publically available prior to the start of releases if obvious hazards of the particular GM mosquitoes released in Malaysia, the Cayman Islands, and Brazil received expert examination. Simple regulatory measures are proposed that would build public confidence and stimulate the independent experimental studies that environmental risk assessments require. Finally, a checklist is provided to assist the general public, journalists, and lawmakers in determining, from documents issued by regulators prior to the start of releases, whether permit approval is likely to have a scientifically high quality basi

    Seasonal Occurrence and Habitat Affi liations of Trichoptera at Mammoth Cave National Park

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    The order Trichoptera is an ecologically-important, diverse group of insects. We investigated the relative abundance and occurrence of these insects at Mammoth Cave National Park (MCNP). We focused our efforts on adults captured at blacklight traps placed across four forest habitats in MCNP on 14 nights during 2010-2011. Large-bodied Trichoptera (≥ 10 mm in length) were identified and enumerated, yielding 2,153 specimens of ≥ 45 species and 11 families. Unique captures were recorded at mixed deciduous-dominated, mixed coniferdominated, and upland deciduous sites (13, 4, and 3 species, respectively). While composition of the assemblage varied across collection sites, as well as seasonally, members of the Hydropsychidae (Hydropsyche spp.) and Leptoceridae (Ceraclea spp.) were the most abundant groups. These two families constituted 93% of total abundance and 65% of species richness across all samples. In this study we detail abundance and richness patterns of Trichoptera across a forest landscape and examine habitats for which data are lacking

    Aquatic Insects of Upper Three Runs Creek, Savannah River Plant, South Carolina. Part IV: Caddisflies (Trichoptera) of the Lower Reaches

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    Ninety-three species of caddisflies, representing 14 families, were identified from collections obtained from two localities on Upper Three Runs Creek, Savannah River Site, Aiken County, South Carolina. Collections of adult caddisflies were made biweekly over a 1-yr period with ultraviolet light traps. The similarity index, Jaccard\u27s Coefficient of Communities, showed that the two sites were over 78% similar with 73 species in common. Three species, Oxyethira setosa Denning, Triaenodes smithi Ross, and Nyctiophylax serratus Lago & Harris, are new distributional records for South Carolina. Two species of Triaenodes are new to science. Other species, which were considered to be endemic to the Upper Three Runs Creek drainage, rare outside of the drainage, or of limited distribution, included Cheumatopsyche richardsoni Gordon, Oxyethira dunbartonensis Kelley, Protoptila morettii Morse, Hydrophysche elissoma Ross, Triaenodes ochraceus (Betten and Mosely), Neotrichia falca Ross, Oecetis morsei Bueno-Soria, and Pycnopsyche virginica (Banks)

    Tidal interactions at the edge of the Local Group: New evidence for tidal features in the Antlia Dwarf Galaxy

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    Using deep B band imaging down to mu_{B} = 26 mag arcsec^{-2}, we present evidence for tidal tails in the Antlia Dwarf galaxy, one of the most distant members of the Local Group. This elongation is in the direction of Antlia's nearest neighbor, the Magellanic-type NGC 3109. The tail is offset by less than 10 degrees from a vector linking the centers of the two galaxies, indicative of interactions between the pair. Combined with the warped disc previously identified in NGC 3109, Antlia and NGC 3109 must be at a small separation for tidal features to be present in Antlia. We calculate that Antlia cannot be completely disrupted by NGC 3109 in a single interaction unless its orbit pericenter is less than 6 kpc, however multiple interactions could significantly alter its morphology. Therefore despite being located right at the edge of the Local Group, environmental effects are playing an important role in Antlia's evolution.Comment: 8 pages, 4 figures, accepted for publication in ApJ

    Strong Lensing Model of SPT-CLJ0356-5337, a Major Merger Candidate at Redshift 1.0359

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    We present an analysis of the mass distribution inferred from strong lensing by SPT-CL J0356-5337, a cluster of galaxies at redshift z = 1.0359 revealed in the follow-up of the SPT-SZ clusters. The cluster has an Einstein radius of Erad=14 for a source at z = 3 and a mass within 500 kpc of M_500kpc = 4.0+-0.8x10^14Msol. Our spectroscopic identification of three multiply-imaged systems (z = 2.363, z = 2.364, and z = 3.048), combined with HST F606W-band imaging allows us to build a strong lensing model for this cluster with an rms of <0.3'' between the predicted and measured positions of the multiple images. Our modeling reveals a two-component mass distribution in the cluster. One mass component is dominated by the brightest cluster galaxy and the other component, separated by ~170 kpc, contains a group of eight red elliptical galaxies confined in a ~9'' (~70 kpc) diameter circle. We estimate the mass ratio between the two components to be between 1:1.25 and 1:1.58. In addition, spectroscopic data reveal that these two near-equal mass cores have only a small velocity difference of 300 km/s between the two components. This small radial velocity difference suggests that most of the relative velocity takes place in the plane of the sky, and implies that SPT-CL J0356-5337 is a major merger with a small impact parameter seen face-on. We also assess the relative contributions of galaxy-scale halos to the overall mass of the core of the cluster and find that within 800 kpc from the brightest cluster galaxy about 27% of the total mass can be attributed to visible and dark matter associated with galaxies, whereas only 73% of the total mass in the core comes from cluster-scale dark matter halos.Comment: 19 pages, 11 figures. Submitted to Ap

    Homoiterons and expansion in ribosomal RNAs

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    AbstractRibosomal RNAs in both prokaryotes and eukaryotes feature numerous repeats of three or more nucleotides with the same nucleobase (homoiterons). In prokaryotes these repeats are much more frequent in thermophile compared to mesophile or psychrophile species, and have similar frequency in both large RNAs. These features point to use of prokaryotic homoiterons in stabilization of both ribosomal subunits. The two large RNAs of eukaryotic cytoplasmic ribosomes have expanded to a different degree across the evolutionary ladder. The big RNA of the larger subunit (60S LSU) evolved expansion segments of up to 2400 nucleotides, and the smaller subunit (40S SSU) RNA acquired expansion segments of not more than 700 nucleotides. In the examined eukaryotes abundance of rRNA homoiterons generally follows size and nucleotide bias of the expansion segments, and increases with GC content and especially with phylogenetic rank. Both the nucleotide bias and frequency of homoiterons are much larger in metazoan and angiosperm LSU compared to the respective SSU RNAs. This is especially pronounced in the tetrapod vertebrates and seems to culminate in the hominid mammals. The stability of secondary structure in polyribonucleotides would significantly connect to GC content, and should also relate to G and C homoiteron content. RNA modeling points to considerable presence of homoiteron-rich double-stranded segments especially in vertebrate LSU RNAs, and homoiterons with four or more nucleotides in the vertebrate and angiosperm LSU RNAs are largely confined to the expansion segments. These features could mainly relate to protein export function and attachment of LSU to endoplasmic reticulum and other subcellular networks

    Development of a telescope for medium-energy gamma-ray astronomy

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    The Advanced Energetic Pair Telescope (AdEPT) is being developed at GSFC as a future NASA MIDEX mission to explore the medium-energy (5–200 MeV) gamma-ray range. The enabling technology for AdEPT is the Three- Dimensional Track Imager (3-DTI), a gaseous time projection chamber. The high spatial resolution 3-D electron tracking of 3-DTI enables AdEPT to achieve high angular resolution gamma-ray imaging via pair production and triplet production (pair production on electrons) in the medium-energy range. The low density and high spatial resolution of 3-DTI allows the electron positron track directions to be measured before they are dominated by Coulomb scattering. Further, the significant reduction of Coulomb scattering allows AdEPT to be the first medium-energy gamma-ray telescope to have high gamma-ray polarization sensitivity. We review the science goals that can be addressed with a medium-energy pair telescope, how these goals drive the telescope design, and the realization of this design with AdEPT. The AdEPT telescope for a future MIDEX mission is envisioned as a 8 m3 active volume filled with argon at 2 atm. The design and performance of the 3-DTI detectors for the AdEPT telescope are described as well as the outstanding instrument challenges that need to be met for the AdEPT mission
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