8,436 research outputs found
Are you serious? From fist bumping to hand hygiene: considering culture, context and complexity in infection prevention intervention research
Infection prevention is an under-resourced research and development topic, with limited evidence for practice in the most basic of measures. A survey of IPS R&D members indicated that what might appear to be simple interactions and interventions in healthcare, such as hand shaking and hand hygiene, should be considered complex interventions taking account of behaviour at the individual and social level as well as contextual factors. Future studies need to be designed utilising comprehensive approaches, for example, the Medical Research Council complex interventions framework, tailored to the country and more local cultural context, if we are to be serious about evidence for infection prevention and control practice
The Evolution of Protoplanetary Disks Around Millisecond Pulsars: The PSR 1257 +12 System
We model the evolution of protoplanetary disks surrounding millisecond
pulsars, using PSR 1257+12 as a test case. Initial conditions were chosen to
correspond to initial angular momenta expected for supernova-fallback disks and
disks formed from the tidal disruption of a companion star. Models were run
under two models for the viscous evolution of disks: fully viscous and layered
accretion disk models. Supernova-fallback disks result in a distribution of
solids confined to within 1-2 AU and produce the requisite material to form the
three known planets surrounding PSR 1257+12. Tidal disruption disks tend to
slightly underproduce solids interior to 1 AU, required for forming the pulsar
planets, while overproducing the amount of solids where no body, lunar mass or
greater, exists. Disks evolving under 'layered' accretion spread somewhat less
and deposit a higher column density of solids into the disk. In all cases,
circumpulsar gas dissipates on year timescales, making
formation of gas giant planets highly unlikely.Comment: 16 pages, 17 figures, Accepted for publication in The Astrophysical
Journal (September 20, 2007 issue
The far field diffraction pattern for corner reflectors with complex reflection coefficients
The far field diffraction pattern of a geometrically perfect corner reflector is examined analytically for normally incident monochromatic light. The states of polarization and the complex amplitudes of the emerging light are expressed through transformation matrices in terms of those of the original incident light for each sextant of the face in a single coordinate system. The analytic expression of the total diffraction pattern is obtained for a circular face. This expression consists of three component functions in addition to the basic Airy function. The coefficient of each function is expressed in terms of complex coefficients of reflectance of the reflecting surface. Some numerical results for different reflecting surfaces, including total internal reflection, are presented. The iso-intensity contours of the diffraction pattern evaluated from the analytical expressions for an uncoated solid corner reflector are also presented along with the photographs of the pattern
Teaching functional patterns through robotic applications
We present our approach to teaching functional programming to First Year Computer Science stu- dents at Middlesex University through projects in robotics. A holistic approach is taken to the cur- riculum, emphasising the connections between different subject areas. A key part of the studentsâ learning is through practical projects that draw upon and integrate the taught material. To support these, we developed the Middlesex Robotic plaTfOrm (MIRTO), an open-source platform built using Raspberry Pi, Arduino, HUB-ee wheels and running Racket (a LISP dialect). In this paper we present the motivations for our choices and explain how a number of concepts of functional programming may be employed when programming robotic applications. We present some studentsâ work with robotics projects: we consider the use of robotics projects to have been a success, both for their value in reinforcing studentsâ understanding of programming concepts and for their value in motivating the students
Unfinished Business: a Review of the Implementation of the Provisions of United Nations General Assembly Resolutions 61/105 and 64/72, Related to the Management of Bottom Fisheries in Areas Beyond National Jurisdiction
In 2006 the General Assembly adopted resolution 61/105, based on a compromise proposal offered by deep-sea fishing nations, which committed States and regional fisheries management organisations [RFMOs] to take specific measures to protect vulnerable marine ecosystems [VMEs] from the adverse impacts of bottom fisheries in the high seas and to ensure the longterm sustainability of deep-sea fish stocks. These measures included conducting impact assessments to determine whether significant adverse impacts[SAIs] to VMEs would occur, managing fisheries to prevent SAIs on VMEs, and closing areas of the high seas to bottom fishing where VMEs are known or likely to occur, unless regulations are in place to prevent SAIs and to manage sustainably deep-sea fish stocks. Based on a review in 2009 of the actions taken by States and RFMOS, the UNGA adoptedresolution 64/72 that reaffirmed resolution 61/105 and strengthened the call for action through committing States, inter alia, to ensure that vessels do not engage in bottom fishing until impact assessments have been carried out and to not authorise bottom fishing activities until the measures in resolutions 64/72 and 61/105 have been adopted andimplemented
Confirmation of the planet around HD 95086 by direct imaging
VLT/NaCo angular differential imaging at L' (3.8 microns) revealed a probable
giant planet comoving with the young and early-type HD 95086 also known to
harbor an extended debris disk. The discovery was based on the proper motion
analysis of two datasets spanning 15 months. However, the second dataset
suffered from bad atmospheric conditions, which limited the significance of the
redetection at the 3 sigma level. In this Letter, we report new VLT/NaCo
observations of HD 95086 obtained on 2013 June 26-27 at L' to recover the
planet candidate. We unambiguously redetect the companion HD 95086 b with
multiple independent pipelines at a signal-to-noise ratio greater than or equal
to 5. Combined with previously reported measurements, our astrometry decisively
shows that the planet is comoving with HD 95086 and inconsistent with a
background object. With a revised mass of 5 pm 2 Jupiter masses, estimated from
its L' photometry and "hot-start" models at 17 pm 4 Myr, HD 95086 b becomes a
new benchmark for further physical and orbital characterization of young giant
planets.Comment: accepted for publication to AP
Seeing motion and apparent motion
In apparent motion experiments, participants are presented with what is in fact a succession of two brief stationary stimuli at two different locations, but they report an impression of movement. Philosophers have recently debated whether apparent motion provides evidence in favour of a particular account of the nature of temporal experience. I argue that the existing discussion in this area is premised on a mistaken view of the phenomenology of apparent motion and, as a result, the space of possible philosophical positions has not yet been fully explored. In particular, I argue that the existence of apparent motion is compatible with an account of the nature of temporal experience that involves a version of direct realism. In doing so, I also argue against two other claims often made about apparent motion, viz. that apparent motion is the psychological phenomenon that underlies motion experience in the cinema, and that apparent motion is subjectively indistinguishable from real motion
Complex host-pathogen coevolution in the Apterostigma fungus-growing ant-microbe symbiosis
BACKGROUND: The fungus-growing ant-microbe symbiosis consists of coevolving microbial mutualists and pathogens. The diverse fungal lineages that these ants cultivate are attacked by parasitic microfungi of the genus Escovopsis. Previous molecular analyses have demonstrated strong phylogenetic congruence between the ants, the ants-cultivated fungi and the garden pathogen Escovopsis at ancient phylogenetic levels, suggesting coevolution of these symbionts. However, few studies have explored cophylogenetic patterns between these symbionts at the recent phylogenetic levels necessary to address whether these parasites are occasionally switching to novel hosts or whether they are diversifying with their hosts as a consequence of long-term host fidelity. RESULTS: Here, a more extensive phylogenetic analysis of Escovopsis lineages infecting the gardens of Apterostigma ants demonstrates that these pathogens display patterns of phylogenetic congruence with their fungal hosts. Particular clades of Escovopsis track particular clades of cultivated fungi, and closely-related Escovopsis generally infect closely-related hosts. Discordance between host and parasite phylogenies, however, provides the first evidence for occasional host-switches or acquisitions of novel infections from the environment. CONCLUSION: The fungus-growing ant-microbe association has a complex coevolutionary history. Though there is clear evidence of host-specificity on the part of diverse Escovopsis lineages, these pathogens have switched occasionally to novel host fungi. Such switching is likely to have profound effects on how these host and parasites adapt to one another over evolutionary time scales and may impact how disease spreads over ecological time scales
Hamiltonian Formulation of Two Body Problem in Wheeler-Feynman electrodynamics
A Hamiltonian formulation for the classical problem of electromagnetic
interaction of two charged relativistic particles is found.Comment: 22 pages, 8 Uuencoded Postscript figure
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