952 research outputs found
Sources of error and confidence intervals for SEA parameters of two coupled rectangular plates
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Soft topographic map for clustering and classification of bacteria
In this work a new method for clustering and building a
topographic representation of a bacteria taxonomy is presented. The method is based on the analysis of stable parts of the genome, the so-called “housekeeping genes”. The proposed method generates topographic maps of the bacteria taxonomy, where relations among different
type strains can be visually inspected and verified. Two well known DNA alignement algorithms are applied to the genomic sequences. Topographic maps are optimized to represent the similarity among the sequences according to their evolutionary distances. The experimental analysis is carried out on 147 type strains of the Gammaprotebacteria
class by means of the 16S rRNA housekeeping gene. Complete sequences of the gene have been retrieved from the NCBI public database. In the experimental tests the maps show clusters of homologous type strains and present some singular cases potentially due to incorrect classification
or erroneous annotations in the database
Intersections of Schubert varieties and eigenvalue inequalities in an arbitrary finite factor
It is known that the eigenvalues of selfadjoint elements a,b,c with a+b+c=0
in the factor R^omega (ultrapower of the hyperfinite II1 factor) are
characterized by a system of inequalities analogous to the classical Horn
inequalities of linear algebra. We prove that these inequalities are in fact
true for elements of an arbitrary finite factor. A matricial (`complete') form
of this result is equivalent to an embedding question formulated by Connes.Comment: 41 pages, many figure
Six Months of Multi-Wavelength Follow-up of the Tidal Disruption Candidate ASASSN-14li and Implied TDE Rates from ASAS-SN
We present ground-based and Swift photometric and spectroscopic observations
of the candidate tidal disruption event (TDE) ASASSN-14li, found at the center
of PGC 043234 ( Mpc) by the All-Sky Automated Survey for SuperNovae
(ASAS-SN). The source had a peak bolometric luminosity of ergs
s and a total integrated energy of ergs radiated
over the months of observations presented. The UV/optical emission of
the source is well-fit by a blackbody with roughly constant temperature of
K, while the luminosity declines by roughly a factor of 16 over
this time. The optical/UV luminosity decline is broadly consistent with an
exponential decline, , with days.
ASASSN-14li also exhibits soft X-ray emission comparable in luminosity to the
optical and UV emission but declining at a slower rate, and the X-ray emission
now dominates. Spectra of the source show broad Balmer and helium lines in
emission as well as strong blue continuum emission at all epochs. We use the
discoveries of ASASSN-14li and ASASSN-14ae to estimate the TDE rate implied by
ASAS-SN, finding an average rate of
per galaxy with a 90% confidence interval of per galaxy. ASAS-SN found roughly 1 TDE for every 70 Type Ia
supernovae in 2014, a rate that is much higher than that of other surveys.Comment: 21 pages, 9 figures, 6 tables. Photometric data presented in this
submission are included as ancillary files. Manuscript updated to reflect
changes made in the published version. For a brief video explaining this
paper, see https://youtu.be/CTbr-d7cWZ
The Young and Bright Type Ia Supernova ASASSN-14lp: Discovery, Early-Time Observations, First-Light Time, Distance to NGC 4666, and Progenitor Constraints
On 2014 Dec. 9.61, the All-Sky Automated Survey for SuperNovae (ASAS-SN or
"Assassin") discovered ASASSN-14lp just days after first light using a
global array of 14-cm diameter telescopes. ASASSN-14lp went on to become a
bright supernova ( mag), second only to SN 2014J for the year. We
present prediscovery photometry (with a detection less than a day after first
light) and ultraviolet through near-infrared photometric and spectroscopic data
covering the rise and fall of ASASSN-14lp for more than 100 days. We find that
ASASSN-14lp had a broad light curve (), a
-band maximum at , a rise time of days, and moderate host--galaxy extinction (). Using ASASSN-14lp we derive a distance modulus for NGC 4666 of
corresponding to a distance of Mpc.
However, adding ASASSN-14lp to the calibrating sample of Type Ia supernovae
still requires an independent distance to the host galaxy. Finally, using our
early-time photometric and spectroscopic observations, we rule out red giant
secondaries and, assuming a favorable viewing angle and explosion time, any
non-degenerate companion larger than .Comment: 12 pages, 9 figures, 4 tables. Accepted to ApJ. Photometric data
presented in this submission are included as an ancillary file. For a brief
video explaining this paper, see https://www.youtube.com/watch?v=1bOV-Cqs-a
Kaon Production and Kaon to Pion Ratio in Au+Au Collisions at \snn=130 GeV
Mid-rapidity transverse mass spectra and multiplicity densities of charged
and neutral kaons are reported for Au+Au collisions at \snn=130 GeV at RHIC.
The spectra are exponential in transverse mass, with an inverse slope of about
280 MeV in central collisions. The multiplicity densities for these particles
scale with the negative hadron pseudo-rapidity density. The charged kaon to
pion ratios are and
for the most central collisions. The ratio is lower than the same
ratio observed at the SPS while the is higher than the SPS result.
Both ratios are enhanced by about 50% relative to p+p and +p
collision data at similar energies.Comment: 6 pages, 3 figures, 1 tabl
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