1,350 research outputs found
Spectroscopy of the enigmatic short-period cataclysmic variable IR Com in an extended low state
We report the occurrence of a deep low state in the eclipsing short-period
cataclysmic variable IR Com, lasting more than two years. Spectroscopy obtained
in this state shows the system as a detached white dwarf plus low-mass
companion, indicating that accretion has practically ceased. The spectral type
of the companion derived from the SDSS spectrum is M6-7, somewhat later than
expected for the orbital period of IR Com. Its radial velocity amplitude,
K_2=419.6+-3.4 km/s, together with the inclination of 75-90deg implies
0.8Msun<Mwd<1.0Msun. We estimate the white dwarf temperature to be ~15000K, and
the absence of Zeeman splitting in the Balmer lines rules out magnetic fields
in excess of ~5 MG. IR Com still defies an unambiguous classification, in
particular the occurrence of a deep, long low state is so far unique among
short-period CVs that are not strongly magnetic.Comment: Revised version, MNRAS Letters in pres
Vocalization-associated respiration patterns: thermography-based monitoring and detection of preparation for calling
Vocal emission requires coordination with the respiratory system. Monitoring the increase in laryngeal pressure, which is needed for vocal production, allows detection of transitions from quiet respiration to vocalization-supporting respiration. Characterization of these transitions could be used to identify preparation for vocal emission and to examine the probability of it manifesting into an actual vocal production event. Specifically, overlaying the subject's respiration with conspecific calls can highlight events of call initiation and suppression, as a means of signalling coordination and avoiding jamming. Here, we present a thermal imaging-based methodology for synchronized respiration and vocalization monitoring of free-ranging meerkats. The sensitivity of this methodology is sufficient for detecting transient changes in the subject's respiration associated with the exertion of vocal production. The differences in respiration are apparent not only during the vocal output, but also prior to it, marking the potential time frame of the respiratory preparation for calling. A correlation between conspecific calls with elongation of the focal subject's respiration cycles could be related to fluctuations in attention levels or in the motivation to reply. This framework can be used for examining the capability for enhanced respiration control in animals during modulated and complex vocal sequences, detecting ‘failed’ vocalization attempts and investigating the role of respiration cues in the regulation of vocal interactions
Another one grinds the dust: variability of the planetary debris disc at the white dwarf SDSS J104341.53+085558.2
We report 9 yr of optical spectroscopy of the metal-polluted white dwarf SDSS J104341.53+085558.2, which presents morphological variations of the line profiles of the 8600 Å Ca II triplet emission from the gaseous component of its debris disc. Similar changes in the shape of the Ca II triplet have also been observed in two other systems that host a gaseous disc, and are likely related to the same mechanism. We report the Mg, Si, and Ca abundances of the debris detected in the photosphere of SDSS J1043+0855, place upper limits on O and Fe, and derive an accretion rate of (2.5–12) × 108 g s−1, consistent with those found in other systems with detected debris discs. The Mg/Si ratio and the upper limit on the Fe/Si ratio of the accreted material broadly agree with those found for the crust of the Earth. We also review the range of variability observed among white dwarfs with planetary debris discs
Mental Health Literacy and Ontario Secondary School Curriculum
Student centered mental health initiatives have seen a rise in implementation as the mental health risks for adolescents and young people are becoming more recognized. However, regardless of these initiatives, youth continue to demonstrate poor mental health which can result in stigmatizing attitudes and behavior, low self-esteem, poor help-seeking behavior, and increased suicide risk. To explore the disconnect between the goal of educational initiatives and their current demonstrated outcomes, this dissertation utilized social constructivist learning theory and school-based mental health literacy to conduct a content analysis of curriculum documents and textbooks in use within Ontario high schools. This case study examined the official Ontario high school curriculum, to answer the following questions: 1) How much exposure do Ontario high school students have to mental health information in the classroom? 2) What is the nature of mental health education within Ontario high schools? The results indicated that Ontario high school students are exposed to very little mental health content within the classroom, with mental health incorporated courses accounting for only 5.1% of the entire curriculum, and mandatory mental health education accounting for 0.004%. The results also indicated that mental health content offered in Ontario high schools may be out-of-date as the average age of content is seven years old come the 2020 school year. Additionally, the curriculum focuses almost primarily on substance-use and addiction while oversimplifying other aspects of mental health and mental illness and does not address the most common mental health issues affecting youth. Overall, the findings from this examination of the Ontario high school curriculum demonstrates that mental health is not incorporated comprehensively nor is it multidimensional in nature and that much work needs to be done to ensure that youth are receiving a well-rounded, well informed, and effective mental health education
Do team processes really have an effect on clinical performance? A systematic literature review
Summary There is a growing literature on the relationship between team processes and clinical performance. The purpose of this review is to summarize these articles and examine the impact of team process behaviours on clinical performance. We conducted a literature search in five major databases. Inclusion criteria were: English peer-reviewed papers published between January 2001 and May 2012, which showed or tried to show (i) a statistical relationship of a team process variable and clinical performance or (ii) an improvement of a performance variable through a team process intervention. Study quality was assessed using predefined quality indicators. For every study, we calculated the relevant effect sizes. We included 28 studies in the review, seven of which were intervention studies. Every study reported at least one significant relationship between team processes or an intervention and performance. Also, some non-significant effects were reported. Most of the reported effect sizes were large or medium. The study quality ranged from medium to high. The studies are highly diverse regarding the specific team process behaviours investigated and also regarding the methods used. However, they suggest that team process behaviours do influence clinical performance and that training results in increased performance. Future research should rely on existing theoretical frameworks, valid, and reliable methods to assess processes such as teamwork or coordination and focus on the development of adequate tools to assess process performance, linking them with outcomes in the clinical settin
Newspaper commentaries on terrorism in China and Australia: A contrastive genre study
This thesis is a contrastive genre study which explores newspaper commentaries on terrorism in Chinese and Australian newspapers. The study examines the textual patterning of the Australian and Chinese commentaries, interpersonal and intertextual features of the texts as well as considers possible contextual factors which might contribute to the formation of the newspaper commentaries in the two different languages and cultures. For the framework of its analysis, the study draws on systemic functional linguistics, English for Specific Purposes and new rhetoric genre studies, critical discourse analysis, and discussions of the role of the mass media in the two different cultures. The study reveals that Chinese writers often use explanatory rather than argumentative expositions in their newspaper commentaries. They seem to distance themselves from outside sources and seldom indicate endorsement of these sources. Australian writers, on the other hand, predominantly use argumentative expositions to argue their points of view. They integrate and manipulate outside sources in various ways to establish and provide support for the views they express. It is argued that these textual and intertextual practices are closely related to contextual factors, especially the roles of the media and opinion discourse in contemporary China and Australia. The study, by providing both a textual and contextual view of the genre under investigation in the two languages and cultures, aims to establish a framework for contrastive rhetoric research which moves beyond the text into the context of production and interpretation of the texts as a way of exploring reasons for the linguistic and rhetorical choices made in the two sets of texts
The gaseous component to planetary debris discs at white dwarfs
Via the spectroscopic detection of metal contamination of white dwarf photospheres, it has been well established that 25 – 50% of these stars host remnant planetary systems. This pollution arises from the accretion of disrupted planetesimals, and the majority of metal-enhanced white dwarfs are actively accreting from a debris disc.
These discs are detected in the form of an infrared excess at 1 – 3% of white dwarfs, and a subset host a co-orbiting gaseous component. In this Thesis, I analyse the morphological evolution of the gaseous emission from debris discs around two white dwarfs, including the prototypical gas disc host SDSS J122859.93+104032.9 (SDSS J1228+1040) which shows variability on short (hourly) and long (yearly) timescales. Long-term monitoring of the emission profiles from gaseous debris discs reveals that the majority of them share this seemingly-periodic, morphological evolution. For SDSS J1228+1040, I could model the variable emission profiles remarkably well by the precession of a fixed, asymmetric intensity pattern in the disc, and I produced the first image of a gaseous debris disc using the method of Doppler tomography. I suggest that the variability of the other gas discs is also generated by fixed intensity patterns in the discs that precess.
Motivated by the detection of the long-term variability of gaseous debris discs, I collected short-cadence spectroscopy of the emission from the debris disc around SDSS J1228+1040 to probe for orbital timescale (' hours) variability. I detected clear, periodic variability in the Ca ii emission lines on a ' 2 hr period, which I interpret as the signature of a planetesimal orbiting within the debris disc. I ruled out other likely scenarios, and I hypothesise that the planetesimal generates the gas we observe, as well as inducing the long- and short-term variability.
Finally, using a spectroscopic sample of white dwarfs from the Sloan Digital Sky Survey, I calculated the fraction of white dwarfs that host a detectable gaseous debris disc as 0.06 _ 0:03 0:02 per cent. This occurrence rate can be combined with the fraction of white dwarfs that host a dusty disc (1 – 3 %) to find that only 1 – 10% of these systems have an observable gaseous component. Determining an occurrence rate using the number of known gas (7) and dust (' 38) discs results in a value up to an order of magnitude larger (' 18 %) than the one I have calculated, and is due to observational bias.
My research has shown that while variability of gaseous debris discs is common, appearing on time-scales of decades, months and hours, their prevalence is not. From the results of my work, I hypothesise that these discs are tracers for the presence of close-in planetesimals. Future observations to identify additional gaseous debris discs, as well as characterising their long- and short-term variability will allow this hypothesis to be tested
Estimating flexibility preferences to resolve temporal scheduling conflicts in activity-based modelling
This paper presents a novel activity-based demand model that combines an optimisation framework for continuous temporal scheduling decisions (i.e. activity timings and durations) with traditional discrete choice models for non-temporal choice dimensions (i.e. activity participation, number and type of tours, and destinations). The central idea of our approach is that individuals resolve temporal scheduling conflicts that arise from overlapping activities, e.g. needing to work and desiring to shop at the same time, in order to maximise their daily utility. Flexibility parameters capture behavioural preferences that penalise deviations from desired timings. This framework has three advantages over existing activity-based modelling approaches: (i) the time conflicts between different temporal scheduling decisions including the activity sequence are treated jointly; (ii) flexibility parameters follow a utility maximisation approach; and (iii) the framework can be used to estimate and simulate a city-scale case study in reasonable time. We introduce an estimation routine that allows flexibility parameters to be estimated using real-world observations as well as a simulation routine to efficiently resolve temporal conflicts using an optimisation model. The framework is applied to the full-time workers of a synthetic population for the city of Lausanne, Switzerland. We validate the model results against reported schedules. The results demonstrate the capabilities of our approach to reproduce empirical observations in a real-world case study
Adaptation in anaesthesia team coordination in response to a simulated critical event and its relationship to clinical performance
Background Recent studies in anaesthesia and intensive care indicate that a team's ability to adapt its coordination activities to changing situational demands is crucial for effective teamwork and thus, safe patient care. This study addresses the relationship between adaptation of team coordination and markers of clinical performance in response to a critical event, particularly regarding which types of coordination activities are used and which team member engages in those coordination activities. Methods Video recordings of 15 two-person anaesthesia teams (anaesthesia trainee plus anaesthesia nurse) performing a simulated induction of general anaesthesia were coded, using a structured observation system for coordination activities. The simulation involved a critical event—asystole during laryngoscopy. Clinical performance was assessed using two separate reaction times related to the critical event. Results Analyses of variance revealed a significant effect of the critical event on team coordination: after the occurrence of the asystole, team members adapted their coordination activities by spending more time on information management—a specific type of coordination activity (F1,28=15.17, P=0.001). No significant effect was found for task management. The increase in information management was related to faster decisions regarding how to respond to the critical event, but only for trainees and not for nurses. Conclusions Our findings support the claim that adaptation of coordination activities is related to improved team performance in healthcare. Moreover, adaptation and its relationship to team performance were found to vary with regard to type of coordination activities and team membe
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