2,226 research outputs found
The broadening of Fe II lines by neutral hydrogen collisions
Data for the broadening of 24188 Fe II lines by collisions with neutral
hydrogen atoms have been computed using the theory of Anstee & O'Mara as
extended to singly ionised species and higher orbital angular momentum states
by Barklem & O'Mara. Data have been computed for all Fe II lines between
observed energy levels in the line lists of Kurucz with log gf > -5 for which
the theory is applicable. The variable energy debt parameter Ep used in
computing the second order perturbation theory potential is chosen to be
consistent with the long range dispersion interaction constant C6 computed
using the f-values from Kurucz.Comment: Accepted for A&A. 5 pages, 5 figures, 2 electronic tables. Tables
will be available via CDS; presently also at
http://www.astro.uu.se/~barklem/papers/fe2_data.tar.g
Unavoidable Multicoloured Families of Configurations
Balogh and Bollob\'as [{\em Combinatorica 25, 2005}] prove that for any
there is a constant such that any set system with at least sets
reduces to a -star, an -costar or an -chain. They proved
. Here we improve it to for some constant
.
This is a special case of the following result on the multi-coloured
forbidden configurations at 2 colours. Let be given. Then there exists a
constant so that a matrix with entries drawn from with
at least different columns will have a submatrix that
can have its rows and columns permuted so that in the resulting matrix will be
either or (for some ), where
is the matrix with 's on the diagonal and 's else
where, the matrix with 's below the diagonal and
's elsewhere. We also extend to considering the bound on the number of
distinct columns, given that the number of rows is , when avoiding a matrix obtained by taking any one of the matrices above
and repeating each column times. We use Ramsey Theory.Comment: 16 pages, add two application
Properties of (0, 1)-matrices without certain configurations
AbstractWe generalize results of Ryser on (0, 1)-matrices without triangles, 3 × 3 submatrices with row and column sums 2. The extremal case of matrices without triangles was previously studied by the author. Let the row intersection of row i and row j (i ≠ j) of some matrix, when regarded as a vector, have a 1 in a given column if both row i and row j do not 0 otherwise. For matrices satisfying some conditions on forbidden configurations and column sums ⩾ 2, we find that the number of linearly independent row intersections is equal to the number of distinct columns. The extremal matrices with m rows and (m2) distinct columns have a unique SDR of pairs of rows with 1's. A triangle bordered with a column of 0's and its (0, 1)-complement are also considered as forbidden configurations. Similar results are obtained and the extremal matrices are closely related to the extremal matrices without triangles
High precision determination of the atmospheric parameters and abundances of the COROT main targets
One of the main goals of the COROT mission is to get precise photometric
observations of selected bright stars in order to allow the modelling of their
interior through asteroseismology. However, in order to interpret the
asteroseismological data, the effective temperature, surface gravity, and
chemical composition of the stars must be known with sufficient accuracy. To
carry out this task, we have developed a spectroscopic method called APASS
(Atmospheric Parameters and Abundances from Synthetic Spectra) which allows
precise analysis of stars with a moderate to high rotational velocity, which is
the case for most primary COROT targets. Our method is based on synthetic
spectra and works differentially with respect to the Sun. Using high
signal-to-noise spectra and the APASS method, we determined the atmospheric
parameters and chemical abundances of 13 primary COROT targets. Our results
agree well with those obtained by Bruntt using his software VWA and with those
obtained with the software TEMPLOGG. However, in both cases, our error bars are
significantly smaller than those of other methods. Our effective temperatures
are also in excellent agreement with those obtained with the IR photometry
method. For five stars with relatively low rotational velocity, we also
performed an analysis with a classical equivalent-width method to test
agreement with APASS results. We show that equivalent-width measurements by
Gaussian or Voigt profile-fitting are sensitive to the rotational broadening,
leading to systematic errors whenever the projected rotation velocity is
non-negligible. The APASS method appears superior in all cases and should thus
be preferred.Comment: 12 pages, 6 figures, 4 tables. Accepted in A&
Streamlines for Motion Planning in Underwater Currents
Motion planning for underwater vehicles must consider the effect of ocean
currents. We present an efficient method to compute reachability and cost
between sample points in sampling-based motion planning that supports
long-range planning over hundreds of kilometres in complicated flows. The idea
is to search a reduced space of control inputs that consists of stream
functions whose level sets, or streamlines, optimally connect two given points.
Such stream functions are generated by superimposing a control input onto the
underlying current flow. A streamline represents the resulting path that a
vehicle would follow as it is carried along by the current given that control
input. We provide rigorous analysis that shows how our method avoids exhaustive
search of the control space, and demonstrate simulated examples in complicated
flows including a traversal along the east coast of Australia, using actual
current predictions, between Sydney and Brisbane.Comment: 7 pages, 4 figures, accepted to IEEE ICRA 2019. Copyright 2019 IEE
Evidence for behavioural interventions addressing condom use fit and feel issues to improve condom use : A Systematic Review
© CSIRO 2019. Open Access Article (CC BY-NC-ND)Continuing high rates of sexually transmissible infections (STIs) in many countries highlight the need to identify effective behavioural interventions. Consistent and correct use of male condoms is a key strategy for the prevention of STIs. However, some men report problems with condom fit (e.g. the size and shape of the condom) and feel (e.g. tightness, irritation, sensitivity), which inhibits their use. We conducted a systematic review to identify existing interventions addressing condom use fit and feel problems. We searched electronic databases for peer-reviewed articles and searched reference lists of retrieved studies. Five studies met the inclusion criteria. These were generally small-scale pilot studies evaluating behavioural interventions to promote safer sex with men aged under 30 years, addressing, among other things, barriers to condom use relating to fit and feel. There were significant increases in the reported use of condoms, including condom use with no errors and problems. Improvements in some condom use mediators were reported, such as condom use self-efficacy, knowledge, intentions and condom use experience. There were mixed findings in terms of the ability of interventions to reduce STI acquisition. Behavioural interventions addressing condom fit and feel are promising in terms of effectiveness but require further evaluation.Peer reviewe
Transient reduction in erythrocyte membrane sialoglycoprotein associated with the presence of elliptocytes
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73806/1/j.1365-2141.1988.00477.x.pd
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