23,205 research outputs found
D-brane Bound States and the Generalised ADHM Construction
We discuss the sigma model description of a D-string bound to k D-fivebranes
in type I string theory. The effective theory is an (0,4) supersymmetric
hyper-Kahler with torsion sigma model on the moduli space of Sp(k) instantons
on R^4. Upon toroidal compactification to five dimensions the model is related
to the type II picture where the target space is a symmetric product of K3's.Comment: 17 pages Phyzzx. Minor corrections, to appear in Nucl. Phys.
Nebula around R Corona Borealis
The star R Corona Borealis (R CrB) shows forbidden lines of [O II], [N II],
and [S II] during the deep minimum when the star is fainter by about 8 to 9
magnitudes from normal brightness, suggesting the presence of nebular material
around it. We present low and high spectral resolution observations of these
lines during the ongoing deep minimum of R CrB, which started in July 2007.
These emission lines show double peaks with a separation of about 170 km/s. The
line ratios of [S II] and [O II] suggest an electron density of about 100
cm. We discuss the physical conditions and possible origins of this low
density gas. These forbidden lines have also been seen in other R Coronae
Borealis stars during their deep light minima and this is a general
characteristic of these stars, which might have some relevance to their
origins.Comment: Proceedings IAU Symposium No.283, 2011 ` Planetary Nebulae: an Eye to
the Future
Low-income consumers' attitudes and behaviour towards access, availability and motivation to eat fruit and vegetables
To determine low-income consumers' attitudes and behaviour towards fruit and vegetables, in particular issues of access to, affordability of and motivation to eat fruit and vegetables. Design and setting: Questionnaire survey mailed to homes owned by a large UK housing association. Participants: Participants were 680 low-income men and women, aged 17-100 years. Results: Age, employment, gender, smoking and marital status all affected attitudes towards access, affordability and motivation to eat fruit and vegetables. Few (7%) participants experienced difficulty in visiting a supermarket at least once a week, despite nearly half having no access to a car for shopping. Fruit and vegetables were affordable to this low-income group in the amounts they habitually bought; purchasing additional fruits and vegetables was seen as prohibitively expensive. Less than 5% felt they had a problem with eating healthily and yet only 18% claimed to eat the recommended 5 or more portions of fruit and vegetables every day. Conclusions: Supported by research, current UK Government policy is driven by the belief that low-income groups have difficulties in access to and affordability of fruit and vegetables. Findings from this particular group suggest that, of the three potential barriers, access and affordability were only a small part of the 'problem' surrounding low fruit and vegetable consumption. Thus, other possible determinants of greater consequence need to be identified. We suggest focusing attention on motivation to eat fruit and vegetables, since no dietary improvement can be achieved if people do not recognise there is a problem
A New Massive Type IIA Supergravity From Compactification
We consider the most general form for eleven dimensional supersymmetry
compatible with on-shell superfields. This allows for the introduction of a
conformal Spin(1,10) connection. In eleven dimensional Minkowski space this
modification is trivial and can be removed by a field redefinition, however,
upon compactification on S^1 it is possible to introduce a non-trivial `Wilson
line'. The resulting ten dimensional supergravity has massive 1-form and 3-form
potentials and a cosmological constant. This theory does not possess a
supersymmetric eightbrane soliton but it does admit a supersymmetric non-static
cosmological solution.Comment: 13 pages, phyzzx. The introduction is clarifed and a reference adde
Ring element dynamic stresses
The stresses in the CTRAPRG and CTRIARG ring elements are not calculated for any of the dynamic solutions in the current COSMIC version of NASTRAN. A DMAP alter sequence for Solution 8 and post-processing program, NASTPOST, are presented to calculate these stresses. Test cases are used which describe the method. The stiffness and the consistent versus concentrated mass problems ascribed to this element are reviewed. The DMAP alter sequence introduces Solution 8 displacements to a Solution 1 module to calculate real and imaginary stress components during the execution of Solution 8. The post-processor, NASTPOST, calculates the magnitude/phase stress results. The DMAP sequence was written specifically for level 52 MSC/NASTRAN, but can certainly be used for any COSMIC version with slight modification
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