4,201 research outputs found
Constituting We the People
We study roles of the thermosphere and exosphere on the Martian ionospheric
structure and ion escape rates in the process of the solar wind-Mars
interaction. We employ a four-species multifluid MHD (MF-MHD) model to simulate
the Martian ionosphere and magnetosphere. The thermosphere background is
taken from the Mars Global Ionosphere Thermosphere Model (M-GITM) and the
oxygen exosphere is adopted from the Mars exosphere Monte Carlo model -
Adaptive Mesh Particle Simulator (AMPS). A total of four cases with the
combination of 1D (globally averaged) and 3D thermospheres and exospheres are
studied.
The ion escape rates calculated by adopting 1D and 3D atmospheres are
similar; however, the latter are required to adequately reproduce MAVEN
ionospheric observations. In addition, our simulations show that the 3D hot
oxygen corona plays an important role in preventing planetary molecular ions
(O and CO) escaping from Mars, mainly resulting from the mass
loading of the high-altitude exospheric O ions. The thermospheric
oxygen atom, however, is demonstrated to be the primary neutral source for
O ion escape during the relatively weak solar cycle 24.Comment: 21 pages, 10 figures, 4 tables, accepted for publication in Journal
of Geophysical Research-Space Physic
Simulated kinetic effects of the corona and solar cycle on high altitude ion transport at Mars
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99008/1/jgra50358.pd
The influence of production mechanisms on pickâup ion loss at Mars
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/97192/1/jgra50057.pd
Marfan syndrome and pregnancy: maternal and neonatal outcomes
Objective
To report outcomes in a recent series of pregnancies in women with Marfan syndrome (MFS).
Design
Retrospective case note review.
Setting
Tertiary referral unit (Chelsea and Westminster and Royal Brompton Hospitals).
Sample
Twenty-nine pregnancies in 21 women with MFS between 1995 and 2010.
Methods
Multidisciplinary review of case records.
Main outcome measures
Maternal and neonatal mortality and morbidity of patients with MFS and healthy controls.
Results
There were no maternal deaths. Significant cardiac complications occurred in five pregnancies (17%): one woman experienced a typeâA aortic dissection; two women required cardiac surgery within 6 months of delivery; and a further two women developed impaired left ventricular function during the pregnancy. Women with MFS were also more likely to have obstetric complications (OR 3.29, 95% CI 1.30â8.34), the most frequent of which was postpartum haemorrhage (OR 8.46, 95% CI 2.52â28.38). There were no perinatal deaths, although babies born to mothers with MFS were delivered significantly earlier than those born to the control group (median 39 versus 40 weeks of gestation, MannâWhitney Uâtest, P = 0.04). These babies were also significantly more likely to be small for gestational age (24% in the MFS group versus 6% in the controls; OR 4.95, 95% CI 1.58â15.55).
Conclusions
Pregnancy in women with MFS continues to be associated with significant rates of maternal, fetal, and neonatal complications. Effective pre-pregnancy counselling and meticulous surveillance during pregnancy, delivery, and the puerperium by an experienced multidisciplinary team are warranted for women with MFS
n-type chalcogenides by ion implantation.
Carrier-type reversal to enable the formation of semiconductor p-n junctions is a prerequisite for many electronic applications. Chalcogenide glasses are p-type semiconductors and their applications have been limited by the extraordinary difficulty in obtaining n-type conductivity. The ability to form chalcogenide glass p-n junctions could improve the performance of phase-change memory and thermoelectric devices and allow the direct electronic control of nonlinear optical devices. Previously, carrier-type reversal has been restricted to the GeCh (Ch=S, Se, Te) family of glasses, with very high Bi or Pb 'doping' concentrations (~5-11 at.%), incorporated during high-temperature glass melting. Here we report the first n-type doping of chalcogenide glasses by ion implantation of Bi into GeTe and GaLaSO amorphous films, demonstrating rectification and photocurrent in a Bi-implanted GaLaSO device. The electrical doping effect of Bi is observed at a 100 times lower concentration than for Bi melt-doped GeCh glasses.This work was supported by the UK EPSRC grants EP/I018417/1, EP/I019065/1 and EP/I018050/1.This is the author accepted manuscript. The final version is available from NPG via http://dx.doi.org/10.1038/ncomms634
Test particle comparison of heavy atomic and molecular ion distributions at Mars
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106919/1/jgra50899.pd
Interval valued (\in,\ivq)-fuzzy filters of pseudo -algebras
We introduce the concept of quasi-coincidence of a fuzzy interval value with
an interval valued fuzzy set. By using this new idea, we introduce the notions
of interval valued (\in,\ivq)-fuzzy filters of pseudo -algebras and
investigate some of their related properties. Some characterization theorems of
these generalized interval valued fuzzy filters are derived. The relationship
among these generalized interval valued fuzzy filters of pseudo -algebras
is considered. Finally, we consider the concept of implication-based interval
valued fuzzy implicative filters of pseudo -algebras, in particular, the
implication operators in Lukasiewicz system of continuous-valued logic are
discussed
Overcoming barriers to engaging socio-economically disadvantaged populations in CHD primary prevention: a qualitative study
<p><b>Background:</b> Preventative medicine has become increasingly important in efforts to reduce the burden of chronic disease in industrialised countries. However, interventions that fail to recruit socio-economically representative samples may widen existing health inequalities. This paper explores the barriers and facilitators to engaging a socio-economically disadvantaged (SED) population in primary prevention for coronary heart disease (CHD).</p>
<p><b>Methods:</b> The primary prevention element of Have a Heart Paisley (HaHP) offered risk screening to all eligible individuals. The programme employed two approaches to engaging with the community: a) a social marketing campaign and b) a community development project adopting primarily face-to-face canvassing. Individuals living in areas of SED were under-recruited via the social marketing approach, but successfully recruited via face-to-face canvassing. This paper reports on focus group discussions with participants, exploring their perceptions about and experiences of both approaches.</p>
<p><b>Results:</b> Various reasons were identified for low uptake of risk screening amongst individuals living in areas of high SED in response to the social marketing campaign and a number of ways in which the face-to-face canvassing approach overcame these barriers were identified. These have been categorised into four main themes: (1) processes of engagement; (2) issues of understanding; (3) design of the screening service and (4) the priority accorded to screening. The most immediate barriers to recruitment were the invitation letter, which often failed to reach its target, and the general distrust of postal correspondence. In contrast, participants were positive about the face-to-face canvassing approach. Participants expressed a lack of knowledge and understanding about CHD and their risk of developing it and felt there was a lack of clarity in the information provided in the mailing in terms of the process and value of screening. In contrast, direct face-to-face contact meant that outreach workers could explain what to expect. Participants felt that the procedure for uptake of screening was demanding and inflexible, but that the drop-in sessions employed by the community development project had a major impact on recruitment and retention.</p>
<p><b>Conclusion:</b> Socio-economically disadvantaged individuals can be hard-to-reach; engagement requires strategies tailored to the needs of the target population rather than a population-wide approach.</p>
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