6,731 research outputs found
A Summary Of: Collecting Sleep, Circadian, Fatigue, and Performance Data in Complex Operational Environments
Sleep loss and circadian misalignment contribute to a meaningful proportion of operational accidents and incidents. Countermeasures and work scheduling designs aimed at mitigating fatigue are typically evaluated in controlled laboratory environments, but the effectiveness of translating such strategies to operational environments can be challenging to assess. This manuscript summarizes an approach for collecting sleep, circadian, fatigue, and performance data in a complex operational environment. We studied 44 airline pilots over 34 days while they flew a fixed schedule, which included a baseline data collection with 5 days of mid-morning flights, four early flights, four high-workload mid-day flights, and four late flights that landed after midnight. Each work block was separated by 3-4 days of rest. To assess sleep, participants wore a wrist-worn research-validated activity monitor continuously and completed daily sleep diaries. To assess the circadian phase, pilots were asked to collect all urine produced in four or eight hourly bins during the 24 h after each duty block for the assessment of 6-sulfatoxymelatonin (aMT6s), which is a biomarker of the circadian rhythm. To assess subjective fatigue and objective performance, participants were provided with a touchscreen device used to complete the Samn-Perelli Fatigue Scale and Psychomotor Vigilance Task (PVT) during and after each flight, and at wake-time, mid-day, and bedtime. Using these methods, it was found that sleep duration was reduced during early starts and late finishes relative to baseline. Circadian phase shifted according to duty schedule, but there was a wide range in the aMT6s peak between individuals on each schedule. PVT performance was worse on the early, high-workload, and late schedules relative to baseline. Overall, the combination of these methods was practical and effective for assessing the influence of sleep loss and circadian phase on fatigue and performance in a complex operational environment
A dynamical and kinematical model of the Galactic stellar halo and possible implications for galaxy formation scenarios
We re-analyse the kinematics of the system of blue horizontal branch field
(BHBF) stars in the Galactic halo (in particular the outer halo), fitting the
kinematics with the model of radial and tangential velocity dispersions in the
halo as a function of galactocentric distance r proposed by Sommer-Larsen,
Flynn & Christensen (1994), using a much larger sample (almost 700) of BHBF
stars. The basic result is that the character of the stellar halo velocity
ellipsoid changes markedly from radial anisotropy at the sun to tangential
anisotropy in the outer parts of the Galactic halo (r greater than approx 20
kpc). Specifically, the radial component of the stellar halo's velocity
ellipsoid decreases fairly rapidly beyond the solar circle, from approx 140 +/-
10 km/s at the sun, to an asymptotic value of 89 +/- 19 km/s at large r. The
rapid decrease in the radial velocity dispersion is matched by an increase in
the tangential velocity dispersion, with increasing r.
Our results may indicate that the Galaxy formed hierarchically (partly or
fully) through merging of smaller subsystems - the 'bottom-up' galaxy formation
scenario, which for quite a while has been favoured by most theorists and
recently also has been given some observational credibility by HST observations
of a potential group of small galaxies, at high redshift, possibly in the
process of merging to a larger galaxy (Pascarelle et al 1996).Comment: Latex, 16 pages. 2 postscript figures. Submitted to the Astrophysical
Journal. also available at http://astro.utu.fi/~cflynn/outerhalo.htm
Public Interest Analysis of the US TPP Proposal for an IP Chapter
This briefing paper provides preliminary analysis of two leaked U.S. proposals for an intellectual property chapter in the Trans Pacific Partnership (TPP) agreement. The U.S. proposal, if adopted, would create the highest intellectual property protection and enforcement standards in any free trade agreement to date. Its provisions are primarily based on, and frequently go beyond, the maximalist and controversial standards of the Korea-US Free Trade Agreement (KORUS), the Anti-Counterfeiting Trade Agreement (ACTA) and US law, while negating the development-oriented flexibilities required by the 2007 New Trade Deal for developing countries and included in the US-Peru Free Trade Agreement. If adopted, the provisions would predictably lead to higher prices and decreased access to a broad range of consumer products in many TPP member countries, from medicines to textbooks to information on the internet, with little or no benefit from increased innovation, creativity or local economic activity. No country, including the US, has an interest in ceding this much policy flexibility to an international agreement. The proposal is particularly inappropriate for developing countries where the risks and effects of exclusionary pricing by monopolists are most acute
Exact diagonalization of the S=1/2 Heisenberg antiferromagnet on finite bcc lattices to estimate properties on the infinite lattice
Here we generate finite bipartite body-centred cubic lattices up to 32
vertices. We have studied the spin one half Heisenberg antiferromagnet by
diagonalizing its Hamiltonian on each of the finite lattices and hence
computing its ground state properties. By extrapolation of these data we obtain
estimates of the T = 0 properties on the infinite bcc lattice. Our estimate of
the T = 0 energy agrees to five parts in ten thousand with third order spin
wave and series expansion method estimates, while our estimate of the staggered
magnetization agrees with the spin wave estimate to within a quarter of one
percent.Comment: 16 pages, LaTeX, 1 ps figure, to appear in J.Phys.
Diffusion and jump-length distribution in liquid and amorphous CuZr
Using molecular dynamics simulation, we calculate the distribution of atomic
jum ps in CuZr in the liquid and glassy states. In both states
the distribution of jump lengths can be described by a temperature independent
exponential of the length and an effective activation energy plus a
contribution of elastic displacements at short distances. Upon cooling the
contribution of shorter jumps dominates. No indication of an enhanced
probability to jump over a nearest neighbor distance was found. We find a
smooth transition from flow in the liquid to jumps in the g lass. The
correlation factor of the diffusion constant decreases with decreasing
temperature, causing a drop of diffusion below the Arrhenius value, despite an
apparent Arrhenius law for the jump probability
Boosting BCG with recombinant modified vaccinia ankara expressing antigen 85A: Different boosting intervals and implications for efficacy trials
Objectives. To investigate the safety and immunogenicity of boosting BCG with modified vaccinia Ankara expressing antigen
85A (MVA85A), shortly after BCG vaccination, and to compare this first with the immunogenicity of BCG vaccination alone and
second with a previous clinical trial where MVA85A was administered more than 10 years after BCG vaccination. Design. There
are two clinical trials reported here: a Phase I observational trial with MVA85A; and a Phase IV observational trial with BCG.
These clinical trials were all conducted in the UK in healthy, HIV negative, BCG naı¨ve adults. Subjects were vaccinated with BCG
alone; or BCG and then subsequently boosted with MVA85A four weeks later (short interval). The outcome measures, safety
and immunogenicity, were monitored for six months. The immunogenicity results from this short interval BCG prime–MVA85A
boost trial were compared first with the BCG alone trial and second with a previous clinical trial where MVA85A vaccination
was administered many years after vaccination with BCG. Results. MVA85A was safe and highly immunogenic when
administered to subjects who had recently received BCG vaccination. When the short interval trial data presented here were
compared with the previous long interval trial data, there were no significant differences in the magnitude of immune
responses generated when MVA85A was administered shortly after, or many years after BCG vaccination. Conclusions. The
clinical trial data presented here provides further evidence of the ability of MVA85A to boost BCG primed immune responses.
This boosting potential is not influenced by the time interval between prior BCG vaccination and boosting with MVA85A. These
findings have important implications for the design of efficacy trials with MVA85A. Boosting BCG induced anti-mycobacterial
immunity in either infancy or adolescence are both potential applications for this vaccine, given the immunological data
presented here. Trial Registration. ClinicalTrials.Oxford University was the sponsor for all the clinical trials reported here
Psychological Safety and Norm Clarity in Software Engineering Teams
In the software engineering industry today, companies primarily conduct their
work in teams. To increase organizational productivity, it is thus crucial to
know the factors that affect team effectiveness. Two team-related concepts that
have gained prominence lately are psychological safety and team norms. Still,
few studies exist that explore these in a software engineering context.
Therefore, with the aim of extending the knowledge of these concepts, we
examined if psychological safety and team norm clarity associate positively
with software developers' self-assessed team performance and job satisfaction,
two important elements of effectiveness.
We collected industry survey data from practitioners (N = 217) in 38
development teams working for five different organizations. The result of
multiple linear regression analyses indicates that both psychological safety
and team norm clarity predict team members' self-assessed performance and job
satisfaction. The findings also suggest that clarity of norms is a stronger
(30\% and 71\% stronger, respectively) predictor than psychological safety.
This research highlights the need to examine, in more detail, the
relationship between social norms and software development. The findings of
this study could serve as an empirical baseline for such, future work.Comment: Submitted to CHASE'201
Psychometric Characteristics of the Connor-Davidson Resilience Scale (CD-RISC) in Postpartum Mothers with Histories of Childhood Maltreatment
Background: There is increased awareness that resilience serves as a protective factor against adverse psychophysiological sequelae in the context of stress. However, there are few instruments to assess this construct in adult populations. The Connor-Davidson resilience scale (CD-RISC) has been developed to assess adaptation following stress exposure. While this instrument has previously demonstrated impressive reliability and construct validity, prior research has not supported the consistency of the originally described factor structure. There is also limited evidence regarding the measurement of resilience in the context of cumulative stress exposure.
Objectives: This research explores the psychometric properties of the CD-RISC in mothers with childhood histories of maltreatment
Materials and Methods: Postpartum women who endorsed a history of childhood abuse or neglect (N = 141) completed the CD-RISC, the childhood trauma questionnaire and other surveys measuring positive and negative health and functioning. We calculated descriptive statistics with percentage counts and means as appropriate. Internal reliability was evaluated by Cronbach’s alpha and the calculation of item-to-total score correlations. Parallel analysis (PA) was utilized to derive the number of retained factors.
Results: A recent parenting transition concomitant with a history of maltreatment was associated with lower CD-RISC scores. Internal reliability and concurrent validity analyses were satisfactory and consistent with predicted hypotheses. Exploratory factor analysis (EFA) supported a four-factor model of resilience with this population.
Conclusions: This research offers further evidence of the reliability and validity of the CD-RISC. Further, the results of the EFA with parallel analysis offer an empirically-driven derivation of factors for this population
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