29,196 research outputs found
Improved chlorate candle provides concentrated oxygen source
Improved chlorate candle is used as a solid, portable source of oxygen in emergency situations. It contains sodium chlorate, iron, barium peroxide, and glass mixed in powdered form. The oxygen evolves from the decomposition of the sodium chlorate when an ignition pellet is electrically initiated
Doctors who pilot the GMC's Tests of Competence: who volunteers and why?
Background: Doctors who are investigated by the General Medical Council (GMC) for performance concerns may be required to take a Test of Competence (ToC). The tests are piloted on volunteer doctors before they are used in Fitness to Practise (FtP) investigations. Objectives: To find out who volunteers to take a pilot ToC and why. Methods: This was a retrospective cohort study. Between February 2011 and October 2012 we asked doctors who volunteered for a test to complete a questionnaire about their reasons for volunteering and recruitment. We analysed the data using descriptive statistics and Pearson’s chi-square test. Results: 301 doctors completed the questionnaire. Doctors who took a ToC voluntarily were mostly women, of white ethnicity, of junior grades, working in general practice and who held a Primary Medical Qualification from the UK. This was a different population to doctors under investigation and all registered doctors in the UK. Most volunteers heard about the GMC’s pilot events through email from a colleague and used the experience to gain exam practice for forthcoming postgraduate exams. Conclusions: The reference group of volunteers are not representative of doctors under FtP investigation. Our findings will be used to inform future recruitment strategies with the aim to encourage better matching of groups who voluntarily pilot a ToC with those under FtP investigation
signals at LEP2 energies in the Minimal Supersymmetric Standard Model
In this paper we compare and into four-fermion production
at centre-of-mass energies typical of LEP2 and somewhat larger. The theoretical
framework considered is the Minimal Supersymmetric Standard Model. The interest
in exploiting the CERN collider at values of greater than
192 GeV could come from the discovery of Supersymmetric signals during runs at
lower energy. If these indicate that a charged Higgs boson exists in the mass
range \MH\approx95-105 GeV, then a few years of running at
GeV and nominal luminosity could make the detection of such scalars feasible,
in the purely leptonic channel and, for small
\tb's, also in the semi-hadronic(leptonic) one . Charged
Higgs bosons of the above nature cannot be produced by the beam energies
approved at present for LEP2. However, if runs beyond the so-called `192 GeV
cryogenic limit' will be approved by the CERN Council, our selection procedure
will enable us to establish the presence, or otherwise, of charged Higgs bosons
in the mentioned mass rangeComment: 30 pages, latex, epsfig, 12 postscript figures, complete paper
available at ftp://axpa.hep.phy.cam.ac.uk/stefano/cavendish_9615 and at
http://www.hep.phy.cam.ac.uk/theory/papers
Dictionary Matching with One Gap
The dictionary matching with gaps problem is to preprocess a dictionary
of gapped patterns over alphabet , where each
gapped pattern is a sequence of subpatterns separated by bounded
sequences of don't cares. Then, given a query text of length over
alphabet , the goal is to output all locations in in which a
pattern , , ends. There is a renewed current interest
in the gapped matching problem stemming from cyber security. In this paper we
solve the problem where all patterns in the dictionary have one gap with at
least and at most don't cares, where and are
given parameters. Specifically, we show that the dictionary matching with a
single gap problem can be solved in either time and
space, and query time , where is the number
of patterns found, or preprocessing time and space: , and query
time , where is the number of patterns found.
As far as we know, this is the best solution for this setting of the problem,
where many overlaps may exist in the dictionary.Comment: A preliminary version was published at CPM 201
Clustering on very small scales from a large sample of confirmed quasar pairs: Does quasar clustering track from Mpc to kpc scales?
We present the most precise estimate to date of the clustering of quasars on
very small scales, based on a sample of 47 binary quasars with magnitudes of
and proper transverse separations of \,kpc. Our
sample of binary quasars, which is about 6 times larger than any previous
spectroscopically confirmed sample on these scales, is targeted using a Kernel
Density Estimation technique (KDE) applied to Sloan Digital Sky Survey (SDSS)
imaging over most of the SDSS area. Our sample is "complete" in that all of the
KDE target pairs with \,kpc in our area
of interest have been spectroscopically confirmed from a combination of
previous surveys and our own long-slit observational campaign. We catalogue 230
candidate quasar pairs with angular separations of <8\arcsec, from which our
binary quasars were identified. We determine the projected correlation function
of quasars () in four bins of proper transverse scale over the
range \,kpc. The implied small-scale
quasar clustering amplitude from the projected correlation function, integrated
across our entire redshift range, is at \,kpc. Our sample is the first spectroscopically confirmed sample of
quasar pairs that is sufficiently large to study how quasar clustering evolves
with redshift at kpc. We find that empirical descriptions of
how quasar clustering evolves with redshift at Mpc also
adequately describe the evolution of quasar clustering at
kpc.Comment: 16 pages, 8 figures, 6 tables, Accepted for publication in MNRA
Heavy Residue Isoscaling as a Probe of the Symmetry Energy of Hot Fragments
The isoscaling properties of isotopically resolved projectile residues from
peripheral collisions of 86Kr (25 MeV/nucleon), 64Ni (25 MeV/nucleon) and 136Xe
(20 MeV/nucleon) beams on various target pairs are employed to probe the
symmetry energy coefficient of the nuclear binding energy. The present study
focuses on heavy projectile fragments produced in peripheral and semiperipheral
collisions near the onset of multifragment emission E*/A = 2-3 MeV). For these
fragments, the measured average velocities are used to extract excitation
energies. The excitation energies, in turn, are used to estimate the
temperatures of the fragmenting quasiprojectiles in the framework the Fermi gas
model. The isoscaling analysis of the fragment yields provided the isoscaling
parameters "alpha" which, in combination with temperatures and isospin
asymmetries provided the symmetry energy coefficient of the nuclear binding
energy of the hot fragmenting quasiprojectiles. The extracted values of the
symmetry energy coefficient at this excitation energy range (2-3 MeV/nucleon)
are lower than the typical liquid-drop model value ~25 MeV corresponding to
ground-state nuclei and show a monotonic decrease with increasing excitation
energy. This result is of importance in the formation of hot nuclei in
heavy-ion reactions and in hot stellar environments such as supernova.Comment: 11 pages, 9 figures, submitted to Phys. Rev.
Use of ERTS data for a multidisciplinary analysis of Michigan resources
There are no author-identified significant results in this report
X-ray Properties of Radio-Selected Dual Active Galactic Nuclei
Merger simulations predict that tidally induced gas inflows can trigger
kpc-scale dual active galactic nuclei (dAGN) in heavily obscured environments.
Previously with the Very Large Array, we have confirmed four dAGN with
redshifts between and projected separations between 4.3 and
9.2 kpc in the SDSS Stripe 82 field. Here, we present X-ray
observations that spatially resolve these dAGN and compare their
multi-wavelength properties to those of single AGN from the literature. We
detect X-ray emission from six of the individual merger components and obtain
upper limits for the remaining two. Combined with previous radio and optical
observations, we find that our dAGN have properties similar to nearby
low-luminosity AGN, and they agree well with the black hole fundamental plane
relation. There are three AGN-dominated X-ray sources, whose X-ray
hardness-ratio derived column densities show that two are unobscured and one is
obscured. The low obscured fraction suggests these dAGN are no more obscured
than single AGN, in contrast to the predictions from simulations. These three
sources show an apparent X-ray deficit compared to their mid-infrared continuum
and optical [OIII] line luminosities, suggesting higher levels of obscuration,
in tension with the hardness-ratio derived column densities. Enhanced
mid-infrared and [OIII] luminosities from star formation may explain this
deficit. There is ambiguity in the level of obscuration for the remaining five
components since their hardness ratios may be affected by non-nuclear X-ray
emissions, or are undetected altogether. They require further observations to
be fully characterized.Comment: 11 pages, 5 figures, Accepted for publication in the Astrophysical
Journa
Wavefront sensing with a brightest pixel selection algorithm
Astronomical adaptive optics systems with open-loop deformable mirror control
have recently come on-line. In these systems, the deformable mirror surface is
not included in the wavefront sensor paths, and so changes made to the
deformable mirror are not fed back to the wavefront sensors. This gives rise to
all sorts of linearity and control issues mainly centred on one question: Has
the mirror taken the shape requested? Non-linearities in wavefront measurement
and in the deformable mirror shape can lead to significant deviations in mirror
shape from the requested shape. Here, wavefront sensor measurements made using
a brightest pixel selection method are discussed along with the implications
that this has for open-loop AO systems. Discussion includes elongated laser
guide star spots and also computational efficiency.Comment: 10 pages, 12 figures, accepted by MNRA
Use of ERTS data for a multidisciplinary analysis of Michigan resources
The author has identified the following significant results. The results of this investigation of ratioing simulated ERTS spectral bands and several non-ERTS bands (all collected by an airborne multispectral scanner) indicate that significant terrain information is available from band-ratio images. Ratio images, which are based on the relative spectral changes which occur from one band to another, are useful for enhancing differences and aiding the image interpreter in identifying and mapping the distribution of such terrain elements as seedling crops, all bare soil, organic soil, mineral soil, forest and woodlots, and marsh areas. In addition, the ratio technique may be useful for computer processing to obtain recognition images of large areas at lower costs than with statistical decision rules. The results of this study of ratio processing of aircraft MSS data will be useful for future processing and evaluation of ERTS-1 data for soil and landform studies. Additionally, the results of ratioing spectral bands other than those currently collected by ERTS-1 suggests that some other bands (particularly a thermal band) would be useful in future satellites
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