770 research outputs found
Ecology of the Squirrel Treefrog (Hyla squirella) in Southern Arkansas
We conducted an ecological study of the Squirrel Treefrog, Hyla squirella near El Dorado, Union Co., Arkansas from May-Oct. 2013. We extended the known distribution by ~2 km and documented the first breeding occurring on 28 May and the first transformation of juveniles on 27 Aug. Three endoparasites were documented: Opalina sp., Nyctotherus cordiformis, and Physaloptera sp. larvae. We also provide information on endoparasites of Florida H. squirella as well as a summary of helminths of this frog
Alcohol Motor Fuels
The proposal to encourage the use of power alcohol made from farm crops grown in the Continental United States, as an aid to agriculture, is not new. Since the last consideration, something more than ten years ago, anhydrous ethyl alcohol has become commercially available. This development makes it feasible to use alcohol-gasoline mixtures. The power alcohol project is thus placed upon a new basis and is worthy of a new consideration
NMR Chemical Shifts of Trace Impurities: Common Laboratory Solvents, Organics, and Gases in Deuterated Solvents Relevant to the Organometallic Chemist
Tables of ^1H and ^(13)C NMR chemical shifts have been compiled for common organic compounds often used as reagents or found as products or contaminants in deuterated organic solvents. Building upon the work of Gottlieb, Kotlyar, and Nudelman in the Journal of Organic Chemistry, signals for common impurities are now reported in additional NMR solvents (tetrahydrofuran-d_8, toluene-d_8, dichloromethane-d_2, chlorobenzene-d_5, and 2,2,2-trifluoroethanol-d_3) which are frequently used in organometallic laboratories. Chemical shifts for other organics which are often used as reagents or internal standards or are found as products in organometallic chemistry are also reported for all the listed solvents
The Production of Propionic Acid from Pentoses by Propionibacterium pentosaceum
Propionibacterium pentosaceum attacks pentoses (xylose, arabinose) with the production of propionic and acetic acids
The Effect of Steffen Waste on the Fermentation of Pentosans from the Corn Stalk
It was found that Steffen waste furnishes a suitable source of nitrogen, salts, and buffers for the growth of Aerobacter pectinovorum on pentosan material prepared from corn-stalks
Testing massive star evolution, star-formation history and feedback at low metallicity : Spectroscopic analysis of OB stars in the SMC Wing
Stars which start their lives with spectral types O and early-B are the
progenitors of core-collapse supernovae, long gamma-ray bursts, neutron stars,
and black holes. These massive stars are the primary sources of stellar
feedback in star-forming galaxies. At low metallicities, the properties of
massive stars and their evolution are not yet fully explored. Here we report a
spectroscopic study of 320 OB stars in the Small Magellanic Cloud. The data,
which we obtained with the ESO Very Large Telescope, were analyzed using
state-of-the-art stellar atmosphere models. We find that stellar winds of our
sample stars are much weaker than theoretically expected. The stellar rotation
rates show a bi-modal distribution. The well-populated upper
Hertzsprung-Russell diagram including our sample OB stars from SMC Wing as well
as additional evolved stars all over SMC from the literature shows a strict
luminosity limit. The comparison with single-star evolutionary tracks suggests
a dichotomy in the fate of massive stars in the SMC. Only stars with
Minit<30M seem to evolve from the main sequence to the cool side of
the HRD to become a red supergiant and to explode as type II-P supernova. In
contrast, stars with Minit>30M appear to stay always hot and might
evolve quasi chemically homogeneously, finally collapsing to relatively massive
black holes. However, we find no indication that chemical mixing is correlated
with rapid rotation. We report extended star-formation episodes in a quiescent
low-density region of the Wing, which is progressing stochastically. We measure
the key parameters of stellar feedback and establish the links between the
rates of star formation and supernovae. Our study reveals that in metal-poor
environments the stellar feedback is dominated by core-collapse supernovae in
combination with winds and ionizing radiation supplied by a few of the most
massive stars.Comment: Accepted for publication in Astronomy & Astrophysic
Dense Antihydrogen: Its Production and Storage to Envision Antimatter Propulsion
We discuss the possibility that dense antihydrogen could provide a path
towards a mechanism for a deep space propulsion system. We concentrate at
first, as an example, on Bose-Einstein Condensate (BEC) antihydrogen. In a
Bose-Einstein Condensate, matter (or antimatter) is in a coherent state
analogous to photons in a laser beam, and individual atoms lose their
independent identity. This allows many atoms to be stored in a small volume. In
the context of recent advances in producing and controlling BECs, as well as in
making antihydrogen, this could potentially provide a revolutionary path
towards the efficient storage of large quantities of antimatter, perhaps
eventually as a cluster or solid.Comment: 12 pages, 3 figure
Novel B(Ar')2(Ar'') hetero-tri(aryl)boranes: a systematic study of Lewis acidity
A series of homo- and hetero-tri(aryl)boranes incorporating pentafluorophenyl, 3,5-bis(trifluoromethyl)phenyl, and pentachlorophenyl groups, four of which are novel species, have been studied as the acidic component of frustrated Lewis pairs for the heterolytic cleavage of H2. Under mild conditions eight of these will cleave H2; the rate of cleavage depending on both the electrophilicity of the borane and the steric bulk around the boron atom. Electrochemical studies allow comparisons of the electrophilicity with spectroscopic measurements of Lewis acidity for different series of boranes. Discrepancies in the correlation between these two types of measurements, combined with structural characterisation of each borane, reveal that the twist of the aryl rings with respect to the boron-centred trigonal plane is significant from both a steric and electronic perspective, and is an important consideration in the design of tri(aryl)boranes as Lewis acids
Ecological and cultural factors underlying the global distribution of prejudice
Prejudiced attitudes and political nationalism vary widely around the world, but there has
been little research on what predicts this variation. Here we examine the ecological and cultural factors underlying the worldwide distribution of prejudice. We suggest that cultures
grow more prejudiced when they tighten cultural norms in response to destabilizing ecological threats. A set of seven archival analyses, surveys, and experiments (∑N = 3,986,402)
find that nations, American states, and pre-industrial societies with tighter cultural norms
show the most prejudice based on skin color, religion, nationality, and sexuality, and that
tightness predicts why prejudice is often highest in areas of the world with histories of ecological threat. People’s support for cultural tightness also mediates the link between perceived ecological threat and intentions to vote for nationalist politicians. Results replicate
when controlling for economic development, inequality, conservatism, residential mobility,
and shared cultural heritage. These findings offer a cultural evolutionary perspective on prejudice, with implications for immigration, intercultural conflict, and radicalization.publishedVersio
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