Measurement and testing problems experienced during FAA's emissions testing of general aviation piston engines

The importance of measuring accurate air and fuel flows as well as the importance of obtaining accurate exhaust pollutant measurements were emphasized. Some of the problems and the corrective actions taken to incorporate fixes and/or modifications were identified

Open educational practices for curriculum enhancement

Open educational resources (OER) and open educational practices (OEP) are relatively new areas in educational research. How OER and OEP can help practitioners enhance curricula is one of a number of under-researched topics. This article aims to enable practitioners to identify and implement appropriate open practices to enhance higher education curricula. To that aim, we put forward a framework of four open educational practices based on patterns of OER reuse (‘as is’ or adapted), mapped against the processes of curriculum design and delivery. The framework was developed from the in-depth analysis of 20 cases of higher education practitioners, which revealed patterns of OER reuse across disciplines, institutions and needs. For each open practice we offer evidence, examples and ideas for application by practitioners. We also put forward recommendations for institutional policies on OER and OE

Ribbon Turbulence

We investigate the non-linear equilibration of a two-layer quasi-geostrophic flow in a channel forced by an imposed unstable zonal mean flow, paying particular attention to the role of bottom friction. In the limit of low bottom friction, classical theory of geostrophic turbulence predicts an inverse cascade of kinetic energy in the horizontal with condensation at the domain scale and barotropization on the vertical. By contrast, in the limit of large bottom friction, the flow is dominated by ribbons of high kinetic energy in the upper layer. These ribbons correspond to meandering jets separating regions of homogenized potential vorticity. We interpret these result by taking advantage of the peculiar conservation laws satisfied by this system: the dynamics can be recast in such a way that the imposed mean flow appears as an initial source of potential vorticity levels in the upper layer. The initial baroclinic instability leads to a turbulent flow that stirs this potential vorticity field while conserving the global distribution of potential vorticity levels. Statistical mechanical theory of the 1-1/2 layer quasi-geostrophic model predict the formation of two regions of homogenized potential vorticity separated by a minimal interface. We show that the dynamics of the ribbons results from a competition between a tendency to reach this equilibrium state, and baroclinic instability that induces meanders of the interface. These meanders intermittently break and induce potential vorticity mixing, but the interface remains sharp throughout the flow evolution. We show that for some parameter regimes, the ribbons act as a mixing barrier which prevent relaxation toward equilibrium, favouring the emergence of multiple zonal jets

A Cognitive Intervention for Everyday Executive Function in Female Survivors of Intimate Partner Violence Related Traumatic Brain Injury, A Single-Case Experimental Design (SCED)

An estimated 31,500,000 females have experienced at least one intimate partner violence (IPV) related traumatic brain injury (TBI), or IPV-TBI in their lifetime in the United States of America (USA) alone. Survivors often experience executive function (EF) impairments, resulting in numerous functional and psychological challenges. Despite this, there are currently no studies into EF interventions for IPV-TBI survivors available. Compensatory cognitive rehabilitation and EF coaching have shown positive outcomes for EF in TBI. The current study aimed to investigate the effects of an intervention, combining cognitive rehabilitation and EF coaching for female survivors of IPV-TBI with EF impairments. A multiple baseline single case experimental design (MB-SCED) was used. Two female participants (age M=51.5, range=44-59) completed the study. The independent variable was a four-week cognitive intervention, the dependent variables were everyday executive function, goal attainment, and health-related quality of life (HRQoL). Analysis revealed that the intervention may have benefits for EF goal attainment, self-reported EF and HRQoL. However, these should be interpreted with caution due to the study limitations. The study highlights the need for further clinical interventions and research for IPV-TBI survivors

A Theory of Jump Bidding in Ascending Auctions

Jump bidding is a commonly observed phenomenon that involves bidders in ascending auctions submitting bids higher than required by the auctioneer. Such behavior is typically explained as due to irrationality or to bidders signaling their value. We present field data that suggests such explanations are unsatisfactory and construct an alternative model in which jump bidding occurs due to strategic concerns and impatience. We go on to examine the impact of jump bidding on the outcome of ascending auctions in an attempt to resolve some policy disputes in the design of ascending auctions.auction theory, ascending auctions, jump bidding

Establishment Wage Differentials

Economists have long known that individual wages depend on a combination of employee and employer characteristics, as well as the interaction of the two. Although it is important to understand how employee and employer characteristics are related to wages, little is known about the magnitude and relation of these wage effects. This is primarily due to the lack of microdata which links individuals to the establishments where they work, but also due to technical difficulties associated with separating out employee and employer effects. This paper uses data from the Occupational Employment Statistics program at the Bureau of Labor Statistics that permit both of these issues to be addressed. Our results show that employer effects contribute substantially to earnings differences across individuals. We also find that establishments that pay well for one occupation also pay well for others. This paper contributes to the growing literature that analyzes firms’ compensation policies, and specifically the topic of employer effects on wages.Establishment Wage Differentials; Occupational Employment Statistics

Characteristics of successful interventions to reduce turnover and increase retention of early career nurses: a systematic review

Background nurse shortages have been identified as central to workforce issues in healthcare systems globally and although interventions to increase the nursing workforce have been implemented, nurses leaving their roles, particularly in the first year after qualification, present a significant barrier to building the nurse workforce. Objective to evaluate the characteristics of successful interventions to promote retention and reduce turnover of early career nurses. Design this is a systematic review Data sources Online databases including Academic Search Complete, Medline, Health Policy reference Centre, EMBASE, Psychinfo, CINAHL and the Cochran Library were searched to identify relevant publications in English published between 2001 and April 2018. Studies included evaluated an intervention to increase retention or reduce turnover and used turnover or retention figures as a measure. Review methods The review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA) guidelines. Studies were quality-assessed using the Joanna Briggs Institute Critical Appraisal tools for Quasi Experimental and Randomised Controlled Trials. Retention/turnover data were used to guide the comparison between studies and appropriate measures of central tendency and dispersion were calculated and presented, based on the normality of the data. Results A total of 11, 656 papers were identified, of which 53 were eligible studies. A wide variety of interventions and components within those interventions were identified to improve nurse retention. Promising interventions appear to be either internship/residency programmes or orientation/transition to practice programmes, lasting between 27-52 weeks, with a teaching and preceptor and mentor component. Conclusions Methodological issues impacted on the extent to which conclusions could be drawn, even though a large number of studies were identified. Future research should focus on standardising the reporting of interventions and outcome measures used to evaluate these interventions and carrying out further research with rigorous methodology. Clinical practice areas are recommended to assess their current interventions against the identified criteria to guide development of their effectiveness. Evaluations of cost-effectiveness are considered an important next step to maximise return on investment

The {\gamma} Dor stars as revealed by Kepler : A key to reveal deep-layer rotation in A and F stars

The {\gamma} Dor pulsating stars present high-order gravity modes, which make them important targets in the intermediate-and low-mass main-sequence region of the Hertzsprung-Russell diagram. Whilst we have only access to rotation in the envelope of the Sun, the g modes of {\gamma} Dor stars can in principle deliver us constraints on the inner layers. With the puzzling discovery of unexpectedly low rotation rates in the core of red giants, the {\gamma} Dor stars appear now as unique targets to explore internal angular momentum transport in the progenitors of red giants. Yet, the {\gamma} Dor pulsations remain hard to detect from the ground for their periods are close to 1 day. While the CoRoT space mission first revealed intriguing frequency spectra, the almost uninterrupted 4-year photometry from the Kepler mission eventually shed a new light on them. It revealed regularities in the spectra, expected to bear signature of physical processes, including rotation, in the shear layers close to the convective core. We present here the first results of our effort to derive exploitable seismic diagnosis for mid- to fast rotators among {\gamma} Dor stars. We confirm their potential to explore the rotation history of this early phase of stellar evolution.Comment: 4 pages, 1 figure, proceedings of the 22nd Los Alamos Stellar Pulsation Conference, "Wide-field variability surveys: a 21st-century perspective" held in San Pedro de Atacama, Chile, Nov. 28-Dec. 2, 201

Determining the metallicity of the solar envelope using seismic inversion techniques

The solar metallicity issue is a long-lasting problem of astrophysics, impacting multi- ple fields and still subject to debate and uncertainties. While spectroscopy has mostly been used to determine the solar heavy elements abundance, helioseismologists at- tempted providing a seismic determination of the metallicity in the solar convective enveloppe. However, the puzzle remains since two independent groups prodived two radically different values for this crucial astrophysical parameter. We aim at provid- ing an independent seismic measurement of the solar metallicity in the convective enveloppe. Our main goal is to help provide new information to break the current stalemate amongst seismic determinations of the solar heavy element abundance. We start by presenting the kernels, the inversion technique and the target function of the inversion we have developed. We then test our approach in multiple hare-and-hounds exercises to assess its reliability and accuracy. We then apply our technique to solar data using calibrated solar models and determine an interval of seismic measurements for the solar metallicity. We show that our inversion can indeed be used to estimate the solar metallicity thanks to our hare-and-hounds exercises. However, we also show that further dependencies in the physical ingredients of solar models lead to a low accuracy. Nevertheless, using various physical ingredients for our solar models, we determine metallicity values between 0.008 and 0.014.Comment: Accepted for publication in MNRA

The role of ethnicity in primary angle-closure glaucoma

Primary angle-closure glaucoma is significantly more common than primary open-angle glaucoma in the East, whereas in Africa and Europe the reverse is true. In order to study the role of ethnic background in the frequency of primary angle-closure glaucoma in Cape Town and, in particular, in people of mixed ethnic background, the so-called 'coloureds', we retrospectively reviewed all patients with primary glaucoma who attended the glaucoma clinic at Groote Schuur Hospital during a 30-month period. Primary angle-closure glaucoma was diagnosed in 11 of 63 (17%) whites, 11 of 85 (13%) blacks and 114 of 244 (46,7%) coloureds with primary glaucoma; the difference is statistically highly significant (P < 0,001). The human leucocyte antigen frequencies in 97 coloured patients with primary angle-closure glaucoma were similar to those found in a control group of individuals with a similar ethnic background. This study highlights the fact that coloureds are more predisposed to primary angleclosure glaucoma than whites or blacks. Because of their strong historical and genetic ties with south-east Asia, this greater prevalence of primary angle-closure glaucoma might be explained by an Eastern influence on the ocular structures of the eye, as opposed to an African or European influence