549 research outputs found
An extension of the inductive approach to the lace expansion
We extend the inductive approach to the lace expansion, previously developed
to study models with critical dimension 4, to be applicable more generally. In
particular, the result of this note has recently been used to prove Gaussian
asymptotic behaviour for the Fourier transform of the two-point function for
sufficiently spread-out lattice trees in dimensions d>8, and it is potentially
also applicable to percolation in dimensions d>6
Extension of the generalised inductive approach to the lace expansion: Full proof
This paper extends the inductive approach to the lace expansion of van der
Hofstad and Slade in order to prove Gaussian asymptotic behaviour for models
with critical dimension other than 4. The results are applied by Holmes to
study sufficiently spread-out lattice trees in dimensions d>8 and may also be
applicable to percolation in dimensions d>6
Choosing the right microcontroller: A comparison of 8-bit Atmel, Microchip and Freescale MCUs
When choosing a microcontroller there are many options, so which platform should you choose? There is little independent information available to help engineers decide which platform might best suit their needs and most designers tend to stick with the brand with which they are familiar. This is a difficult question to answer without bias if the people
conducting the evaluations have had previous experience with MCU programming predominantly on one platform. This article draws on a case study. We built three “Smart” Sprinkler Taps, small, self-contained irrigation controllers, differing only in the microcontroller unit (MCU) on the inside. We compare cost, development software quality and hardware performance from the perspective of a new user to each of the platforms
Locating the LCROSS Impact Craters
The Lunar CRater Observations and Sensing Satellite (LCROSS) mission impacted
a spent Centaur rocket stage into a permanently shadowed region near the lunar
south pole. The Sheperding Spacecraft (SSC) separated \sim9 hours before impact
and performed a small braking maneuver in order to observe the Centaur impact
plume, looking for evidence of water and other volatiles, before impacting
itself. This paper describes the registration of imagery of the LCROSS impact
region from the mid- and near-infrared cameras onboard the SSC, as well as from
the Goldstone radar. We compare the Centaur impact features, positively
identified in the first two, and with a consistent feature in the third, which
are interpreted as a 20 m diameter crater surrounded by a 160 m diameter ejecta
region. The images are registered to Lunar Reconnaisance Orbiter (LRO)
topographical data which allows determination of the impact location. This
location is compared with the impact location derived from ground-based
tracking and propagation of the spacecraft's trajectory and with locations
derived from two hybrid imagery/trajectory methods. The four methods give a
weighted average Centaur impact location of -84.6796\circ, -48.7093\circ, with
a 1{\sigma} un- certainty of 115 m along latitude, and 44 m along longitude,
just 146 m from the target impact site. Meanwhile, the trajectory-derived SSC
impact location is -84.719\circ, -49.61\circ, with a 1{\sigma} uncertainty of 3
m along the Earth vector and 75 m orthogonal to that, 766 m from the target
location and 2.803 km south-west of the Centaur impact. We also detail the
Centaur impact angle and SSC instrument pointing errors. Six high-level LCROSS
mission requirements are shown to be met by wide margins. We hope that these
results facilitate further analyses of the LCROSS experiment data and follow-up
observations of the impact region.Comment: Accepted for publication in Space Science Review. 24 pages, 9 figure
Individual-level and plant-level predictors of acute, traumatic occupational injuries in a manufacturing cohort
Objectives: Workplace and contextual factors that may affect risk for worker injury are not well described. This study used results from an employee job satisfaction survey to construct aggregate indicators of the work environment and estimate the relative contribution of those factors to injury rates in a manufacturing cohort. Methods: Principal components analysis was used to construct four plant-level factors from responses to a 32 question survey of the entire workforce, administered in 2006. Multilevel Poisson regression was used to evaluate the relationship between injury rate, individual-level and plant-level risk factors, unionisation and plant type. Results: Plant-level ‘work stress’ (incident rate ratio (IRR)=0.50, 95% CI 0.28 to 0.90) was significant in the multilevel model, indicating the rate of injury for an average individual in that plant was halved (conditional on plant) when job stress decreased by a tertile. ‘Overall satisfaction’, ‘work environment’ and ‘perception of supervisor’ showed the same trend but were not significant. Unionisation was protective (IRR=0.40, 95% CI 0.17 to 0.95) as was any plant type compared with smelter. Conclusions: We demonstrated utility of data from a human resources survey to construct indicators of the work environment. Our research suggests that aspects of the work environment, particularly work stress and unionisation, may have a significant effect on risk for occupational injury, emphasising the need for further multilevel studies. Our work would suggest monitoring of employee perceptions of job stress and the possible inclusion of stress management as a component of risk reduction programmes
Facilitating admissions of diverse students: A six-point, evidence-informed framework for pipeline and program development
Introduction Several national level calls have encouraged reconsideration of diversity issues in medical education. Particular interest has been placed on admissions, as decisions made here shape the nature of the future physician workforce. Critical analysis of current practices paired with evidence-informed policies may counter some of the barriers impeding access for underrepresented groups.
Methods We present a framework for diversity-related program development and evaluation grounded within a knowledge translation framework, and supported by the initiation of longitudinal collection of diversity-related data. We provide an illustrative case study for each component of the framework. Descriptive analyses are presented of pre/post intervention diversity metrics if applicable and available.
Results The framework’s focal points are: 1) data-driven identification of underrepresented groups, 2) pipeline development and targeted recruitment, 3) ensuring an inclusive process, 4) ensuring inclusive assessment, 5) ensuring inclusive selection, and 6) iterative use of diversity-related data. Case studies ranged from wording changes on admissions websites to the establishment of educational and administrative offices addressing needs of underrepresented populations.
Conclusions We propose that diversity-related data must be collected on a variety of markers, developed in partnership with stakeholders who are most likely to facilitate implementation of best practices and new policies.</jats:p
Vertical integration and firm boundaries : the evidence
Since Ronald H. Coase's (1937) seminal paper, a rich set of theories has been developed that deal with firm boundaries in vertical or input–output structures. In the last twenty-five years, empirical evidence that can shed light on those theories also has been accumulating. We review the findings of empirical studies that have addressed two main interrelated questions: First, what types of transactions are best brought within the firm and, second, what are the consequences of vertical integration decisions for economic outcomes such as prices, quantities, investment, and profits. Throughout, we highlight areas of potential cross-fertilization and promising areas for future work
A UK validation of the Stages of Recovery Instrument
Objective: There is considerable interest in the concept of recovery from psychosis. Consumers describe recovery as a process as opposed to a clinical outcome. However, measures of recovery have an important role in the development of recovery-based mental health services. This study sought to investigate the validity and reliability of the Stages of Recovery Instrument (STORI) (Andresen et al., 2006). This is an Australian instrument chosen as a promising measure of recovery developed from the perspectives of consumer accounts.Method: A questionnaire design was used to investigate the following aspects of validity: face validity and feasibility; concurrent validity; construct validity; and test-retest reliability. Fifty (50) people from the caseloads of three specialist mental health teams in a London borough completed the STORI, the Recovery Assessment Scale (RAS) (Corrigan et al., 1999) and a feedback questionnaire. Twenty two (22) people completed the STORI a second time for the purposes of test-retest reliability exploration.Results: Participants' responses to the feedback questionnaire were mainly positive. This was seen as evidence of face validity and feasibility. Correlations between the STORI and the RAS provided evidence of concurrent validity. Cluster analysis revealed that the STORI items formed three clusters rather than five. Strong correlations between the first and second STORI administrations provided initial evidence for the test-retest reliability.Conclusions: The STORI can be used to measure recovery concepts in the UK. However, it does not measure the five-stage model on which it was based. A three-stage model of recovery might best form the basis of future recovery research
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