24,391 research outputs found
RESURRECTED RECORDS: “NEW” REPTILE OCCURRENCE RECORDS FOR MONTGOMERY COUNTY, INDIANA
Current and historic records of species occurrences in particular localities enable researchers to monitor changes in species distribution and abundance. While current fauna can be documented with sufficient effort, missing historical records represent data that can never again be obtained. It is with this importance in mind that we report for the first time records of eight reptile species in Montgomery County, Indiana, USA, that were documented in 1964, though no vouchered specimens persist. These species include: Sternotherus odoratus, Terrapene carolina carolina, Chrysemys picta marginata, Apalone spinifera spinifera, Thamnophis sauritus sauritus, Storeria dekayi wrightorum, Lampropeltis calligaster, Lampropeltis triangulum. We also provide a list of the 23 currently documented reptile species that occur (or have occurred recently) in Montgomery County
The Diffuse Source at the Center of LMC SNR 0509-67.5 is a Background Galaxy at z = 0.031
Type Ia supernovae (SNe Ia) are well-known for their use in the measurement
of cosmological distances, but our continuing lack of concrete knowledge about
their progenitor stars is both a matter of debate and a source of systematic
error. In our attempts to answer this question, we presented unambiguous
evidence that LMC SNR 0509-67.5, the remnant of an SN Ia that exploded in the
Large Magellanic Cloud 400 +/- 50 years ago, did not have any point sources
(stars) near the site of the original supernova explosion, from which we
concluded that this particular supernova must have had a progenitor system
consisting of two white dwarfs (Schaefer & Pagnotta 2012). There is, however,
evidence of nebulosity near the center of the remnant, which could have been
left over detritus from the less massive WD, or could have been a background
galaxy unrelated to the supernova explosion. We obtained long-slit spectra of
the central nebulous region using GMOS on Gemini South to determine which of
these two possibilities is correct. The spectra show H-alpha emission at a
redshift of z = 0.031, which implies that the nebulosity in the center of LMC
SNR 0509-67.5 is a background galaxy, unrelated to the supernova.Comment: 2 figures, accepted for publication in Ap
The Minimum Amount of Stars a Galaxy Will Form
We present an analysis of the atomic hydrogen and stellar properties of 38
late-type galaxies in the local Universe covering a wide range of HI
mass-to-light ratios (M_HI/L_B), stellar luminosities, and surface
brightnesses. From these data we have identified an upper envelope for the
M_HI/L_B as a function of galaxy luminosity. This implies an empirical relation
between the minimum amount of stars a galaxy will form and its initial baryonic
mass. While the stellar mass of a galaxy seems to be only loosely connected to
its baryonic mass, the latter quantity is strongly linked to the galaxy's
dynamical mass as it is observed in the baryonic Tully-Fisher relation. We find
that dwarf irregular galaxies with generally high M_HI/L_B-ratios follow the
same trend as defined by lower M_HI/L_B giant galaxies, but are underluminous
for their rotation velocity to follow the trend in a stellar mass Tully-Fisher
relation, suggesting that the baryonic mass of the dwarf galaxies is normal but
they have failed to produced a sufficient amount of stars. Finally, we present
a three dimensional equivalent to the morphology-density relation which shows
that high M_HI/L_B galaxies preferentially evolve and/or survive in low-density
environments. We conclude that an isolated galaxy with a shallow dark matter
potential can retain a large portion of its baryonic matter in the form of gas,
only producing a minimum quantity of stars necessary to maintain a stable gas
disk.Comment: 37 Pages, 7 Figures. Accepted for publication in A
A -adic RanSaC algorithm for stereo vision using Hensel lifting
A -adic variation of the Ran(dom) Sa(mple) C(onsensus) method for solving
the relative pose problem in stereo vision is developped. From two 2-adically
encoded images a random sample of five pairs of corresponding points is taken,
and the equations for the essential matrix are solved by lifting solutions
modulo 2 to the 2-adic integers. A recently devised -adic hierarchical
classification algorithm imitating the known LBG quantisation method classifies
the solutions for all the samples after having determined the number of
clusters using the known intra-inter validity of clusterings. In the successful
case, a cluster ranking will determine the cluster containing a 2-adic
approximation to the "true" solution of the problem.Comment: 15 pages; typos removed, abstract changed, computation error remove
Evolutionary Timescale of the DAV G117-B15A: The Most Stable Optical Clock Known
We observe G117-B15A, the most precise optical clock known, to measure the
rate of change of the main pulsation period of this blue-edge DAV white dwarf.
Even though the obtained value is only within 1 sigma, Pdot = (2.3 +/- 1.4) x
10^{-15} s/s, it is already constraining the evolutionary timescale of this
cooling white dwarf star.Comment: Accepted for publication in ApJ
Transcriptome-wide analysis reveals different categories of response to a standardised immune challenge in a wild rodent
Individuals vary in their immune response and, as a result, some are more susceptible to infectious disease than others. Little is known about the nature of this individual variation in natural populations, or which components of immune pathways are most responsible, but defining this underlying landscape of variation is an essential first step to understanding the drivers of this variation and, ultimately, predicting the outcome of infection. We describe transcriptome-wide variation in response to a standardised immune challenge in wild field voles. We find that markers can be categorised into a limited number of types. For the majority of markers, the response of an individual is dependent on its baseline expression level, with significant enrichment in this category for conventional immune pathways. Another, moderately sized, category contains markers for which the responses of different individuals are also variable but independent of their baseline expression levels. This category lacks any enrichment for conventional immune pathways. We further identify markers which display particularly high individual variability in response, and could be used as markers of immune response in larger studies. Our work shows how a standardised challenge performed on a natural population can reveal the patterns of natural variation in immune response
An Analytical Study for Subsonic Oblique Wing Transport Concept
The oblique wing concept has been investigated for subsonic transport application for a cruise Mach number of 0.95. Three different mission applications were considered and the concept analyzed against the selected mission requirements. Configuration studies determined the best area of applicability to be a commercial passenger transport mission. The critical parameter for the oblique wing concept was found to be aspect ratio which was limited to a value of 6.0 due to aeroelastic divergence. Comparison of the concept final configuration was made with fixed winged configurations designed to cruise at Mach 0.85 and 0.95. The crossover Mach number for the oblique wing concept was found to be Mach 0.91 for takeoff gross weight and direct operating cost. Benefits include reduced takeoff distance, installed thrust and mission block fuel and improved community noise characteristics. The variable geometry feature enables the final configuration to increase range by 10% at Mach 0.712 and to increase endurance by as much as 44%
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