Stream-field interactions in the magnetic accretor AO Piscium

UV spectra of the magnetic accretor AO Psc show absorption features for half the binary orbit. The absorption is unlike the wind-formed features often seen in similar stars. Instead, we attribute it to a fraction of the stream that overflows the impact with the accretion disk. Rapid velocity variations can be explained by changes in the trajectory of the stream depending on the orientation of the white-dwarf's magnetic field. Hence we are directly observing the interaction of an accretion stream with a rotating field. We compare this behavior to that seen in other intermediate polars and in SW Sex stars.Comment: Accepted for ApJ; 6 page

Discovery of an X-ray pulsar in the low-mass X-ray binary 2A 1822-371

We report the discovery of 0.59 s X-ray pulsations from the low-mass X-ray binary, 5.57 hr dipping and eclipsing ADC source 2A 1822-371. Pulse arrival time analysis indicates a circular orbit with e < 0.03 (95% confidence) and an asini for the neutron star of 1.006(5) lightseconds, implying a mass function of (2.03+-0.03) x 10^-2 M_sun. The barycentric pulse period was 0.59325(2) s in 1996.270 and 0.59308615(5) s in 1998.205, indicating an average spin up with P_dot/P = (-1.52+-0.02) x 10^-4 yr^-1. For a magnetic field strength of ~1--5 x 10^12 G as derived from the X-ray spectrum the implied intrinsic X-ray luminosity is ~2-4 x 10^37 erg s^-1. The pulse amplitude is low, but increases steeply as a function of energy from a sinusoidal amplitude of 0.25% in 2-5.4 keV to ~3% above 20 keV. We discuss the constraints on the masses of the companion star and the fact that several aspects of the energy spectrum are in qualitative accordance with that of a strongly magnetised neutron star.Comment: 6 pages long, including 4 figures, uses emulateapj5, accepted for ApJL, Replaced figure

Learning medical alarms whilst performing other tasks.

Two studies are reported which first observe, and then attempt to replicate, the cognitive demands of intensive care unit (ICU) activity whilst concurrently learning audible alarms. The first study, an observational study in an ICU ward, showed that the alarms are very frequent and co-occur with some activities more than others. The three most frequently observed activities observed in the ICU were drugs (calculation, preparation and administration), patient observation and talking. The cognitive demands of these activities were simulated in a second, laboratory-based experiment in which alarms were learned. The results showed that performance in the alarm task generally improved as participants were exposed to more repetitions of those alarms, but that performance decrements were observed in the secondary tasks, particularly when there were two or three of them. Some confusions between the alarms persisted to the end of the study despite prolonged exposure to the alarms, confusions which were likely caused by both acoustic and verbal labelling similarities. PRACTITIONER SUMMARY: The cognitive demands of working in an ICU were observed and simulated whilst alarms were learned. Alarms should generally avoid sharing similar rhythmic (and other) characteristics. The simulation task described here could be used for testing alarm learning without requiring a clinical environment

Passing crisis and emergency risk communications: the effects of communication channel, information type, and repetition.

Three experiments explore several factors which influence information transmission when warning messages are passed from person to person. In Experiment 1, messages were passed down chains of participants using five different modes of communication. Written communication channels resulted in more accurate message transmission than verbal. In addition, some elements of the message endured further down the chain than others. Experiment 2 largely replicated these effects and also demonstrated that simple repetition of a message eliminated differences between written and spoken communication. In a final field experiment, chains of participants passed information however they wanted to, with the proviso that half of the chains could not use telephones. Here, the lack of ability to use a telephone did not affect accuracy, but did slow down the speed of transmission from the recipient of the message to the last person in the chain. Implications of the findings for crisis and emergency risk communication are discussed

The influence of auditory feedback on speed choice, violations and comfort in a driving simulation game

Two experiments are reported which explore the relationships between auditory feedback (engine noise), speed choice, driving violations and driver comfort. Participants played a driving simulation game with different levels of auditory feedback in the form of engine noise. In Experiment 1, a between-subjects design revealed that no noise and low levels of engine noise (65 dB(A)) resulted in participants driving at faster speeds than in the medium (75 dB(A)) and high (85 dB(A)) levels of engine noise conditions. The low noise feedback conditions were also associated with decreases in driver comfort. Experiment 2 also demonstrated that low levels of engine noise feedback (no feedback and 70 dB(A)) were associated with increases in driving speed, and driving violations relative to higher levels of feedback (75 dB(A) and 80 dB(A)). Implications exist for current car manufacturing trends which emphasise a growing increase in noise insulation for the driver. © 2011 Elsevier Ltd. All rights reserved

The effects of label design characteristics on perceptions of genetically modified food

Objective. To explore the effects on perceptions of labelling food for genetically modified content. Background: there is increasing public pressure for the compulsory labelling of genetically modified food content on all food products, and yet little is known about how the design and content of such food labels will influence product perceptions. The current research draws upon warning label research - a field in which the effect of label design manipulations on perceptions of, and responses to, potential or perceived risks is well documented. Method. Two experiments are reported that investigate how label design features influence the perception of genetically modified foods. The effects of label colour (red, blue and green), wording style (definitive vs. probabilistic and explicit vs. non-explicit) and information source (government agency, consumer group and manufacturer) on hazard perceptions and purchase intentions were measured. Results. Hazard perceptions and purchase intentions were both influenced by label design characteristics in predictable ways. Any reference to genetic modification, even if the label is stating that the product is free of genetically modified ingredients, increased hazard perception, and decreased purchase intentions, relative to a no-label condition. Conclusion. Label design effects generalise from warning label research to influence the perception of genetically modified foods in predictable ways. Application. The design of genetically modified food labels. © 2012 Copyright Taylor and Francis Group, LLC

An EUV Study of the Intermediate Polar EX Hydrae

On 2000 May 5, we began a large multi-wavelength campaign to study the intermediate polar, EX Hydrae. The simultaneous observations from six satellites and four telescopes were centered around a one million second observation with EUVE. Although EX Hydrae has been studied previously with EUVE, our higher signal-to-noise observations present new results and challenge the current IP models. Previously unseen dips in the light curve are reminiscent of the stream dips seen in polar light curves. Also of interest is the temporal extent of the bulge dip; approximately 0.5 in phase, implying that the bulge extends over half of the accretion disk. We propose that the magnetic field in EX Hydrae is strong enough (a few MG) to begin pulling material directly from the outer edge of the disk, thereby forming a large accretion curtain which would produce a very broad bulge dip. This would also result in magnetically controlled accretion streams originating from the outer edge of the disk. We also present a period analysis of the photometric data which shows numerous beat frequencies with strong power and also intermittent and wandering frequencies, an indication that physical conditions within EX Hya changed over the course of the observation. Iron spectral line ratios give a temperature of log T=6.5-6.9 K for all spin phases and a poorly constrained density of n_e=10^10-10^11 cm^-3 for the emitting plasma. This paper is the first in a series detailing our results from this multi-wavelength observational campaign.Comment: 27 pages, 7 figures, accepted for publication in Ap

The "K-Correction" for Irradiated Emission Lines in LMXBs: Evidence for a Massive Neutron Star in X1822-371 (V691 CrA)

We study the K-correction for the case of emission lines formed in the X-ray illuminated atmosphere of a Roche lobe filling star. We compute the K-correction as function of the mass ratio 'q' and the disc flaring angle 'alpha' using a compact binary code where the companion's Roche lobe is divided into 10^5 resolution elements. We also study the effect of the inclination angle in the results. We apply our model to the case of the neutron star low-mass X-ray binary X1822-371 (V691 CrA), where a K-emission velocity K_em=300 +-8 km/s has been measured by Casares et al. (2003). Our numerical results, combined with previous determination of system parameters, yields 1.61Msun < M_NS < 2.32Msun and 0.44Msun < M_2 < 0.56Msun for the two binary components(i. e. 0.24 < q < 0.27), which provide a compelling evidence for a massive neutron star in this system. We also discuss the implications of these masses into the evolutionary history of the binary.Comment: 6 pages, 5 figures. Accepted for publication in Ap

A review of human factors principles for the design and implementation of medication safety alerts in clinical information systems.

The objective of this review is to describe the implementation of human factors principles for the design of alerts in clinical information systems. First, we conduct a review of alarm systems to identify human factors principles that are employed in the design and implementation of alerts. Second, we review the medical informatics literature to provide examples of the implementation of human factors principles in current clinical information systems using alerts to provide medication decision support. Last, we suggest actionable recommendations for delivering effective clinical decision support using alerts. A review of studies from the medical informatics literature suggests that many basic human factors principles are not followed, possibly contributing to the lack of acceptance of alerts in clinical information systems. We evaluate the limitations of current alerting philosophies and provide recommendations for improving acceptance of alerts by incorporating human factors principles in their design

A Serendipitous XMM-Newton Observation of the Intermediate Polar WX Pyx

We briefly describe a serendipitous observation of the little-studied intermediate polar WX Pyx using XMM-Newton. The X-ray spin period is 1557.3 sec, confirming the optical period published in 1996. An orbital period of approximately 5.54 hr is inferred from the separation of the spin-orbit sidelobe components. The soft and hard band spin-folded light curves are nearly sinusoidal in shape. The best-fit spectrum is consistent with a bremsstrahlung temperature of about 18 keV. An upper limit of approximately 300 eV is assigned to the presence of Fe line emission. WX Pyx lies near TX and TV Col in the P_spin-P_orb plane.Comment: 5 pages, 5 figs; accepted A&A 2004 Dec