1,206 research outputs found
Use and abuse of statistics in tobacco industry-funded research on standardised packaging
In this commentary we consider the validity of tobacco industry-funded research on the effects of standardised packaging in Australia. As the first country to introduce standardised packs, Australia is closely watched, and Philip Morris International has recently funded two studies into the impact of the measure on smoking prevalence. Both of these papers are flawed in conception as well as design but have nonetheless been widely publicised as cautionary tales against standardised pack legislation. Specifically, we focus on the low statistical significance of the analytical methods used and the assumption that standardised packaging should have an immediate large impact on smoking prevalence
Developing the Next Generation of Physics Assessments
Science education at all levels is currently undergoing dramatic changes to
its curricula and developing assessments for these new curricula is paramount.
We have used the basis of many of these new changes (scientific practices,
crosscutting concepts, and core ideas) to develop sets of criteria that can be
used to guide assessment development for this new curriculum. We present a case
study that uses the criteria we have developed to revise a traditional physics
assessment item into an assessment item that is much more aligned with the
goals of current transformation efforts. Assessment items developed using this
criteria can be used to assess student learning of both the concepts and
process of science.Comment: Revised version for PERC 2015 Conference Proceeding
Film boiling of saturated liquid flowing upward through a heated tube : high vapor quality range
Film boiling of saturated liquid flowing upward through a uniformly heated tube has been studied for the case in which pure saturated liquid enters the tube and nearly saturated vapor is discharged. Since a previous study at the M.I.T. Heat Transfer Laboratory covered the case in which only a small percentage of the total mass flow is vaporized, this investigation has been concentrated on film boiling in the region where the vapor quality is greater than 10 percent. Visual studies of film boiling of liquid nitrogen flowing through an electrically conducting pyrex tube have been made to determine the characteristics of the two-phase flow regimes which occur as a result of the film boiling process. It was found that the annular flow regime with liquid in the core and vapor between the liquid and the tube wall, which exists at very low qualities, is broken up at higher qualities to form a dispersed flow of droplets and filaments of liquid carried along in a vapor matrix. A stainless steel test section having a .319 inch ID and heated electrically, has been used to obtain experimental data of wall temperature distributions along the tube and local heat transfer coefficients for different heat fluxes and flow rates with liquid nitrogen as the teit fluid. Heat flux has been varied from 3500 2 to 30000 BTU/hr-ft and mass velocity from 70000 to 210000 lbm/hr-ft2. From these tests, values of wall superheat, (Tw -Ts ), from 200 to w S 975[degree]F and heat transfer coefficients from 11.1 to 65.5 BTU/hr-ft2-[degree] F have been obtained. A theoretical derivation using the Dittus-Boelter equation as an i,7mptote for the heat transfer to pure vapor has demonstrated that a significant amount of vapor superheat is present throughout the film boiling process. The mechanism of the heat transfer process in the dispersed flow region has been described by a two step theory in which 1) all ofthe heat from the wall is transferred to the vapor and 2) heat iSponsored by the National Science Foundatio
Recommended from our members
Impact of 'high-profile' public reporting on utilization and quality of maternity care in England: a difference-in-difference analysis
Objectives
To evaluate the impact of high profile public reporting on utilisation and perceived quality of maternity services in England.
Methods
Analysis of national hospital administrative data using difference in difference models with propensity score matching and analysis of two maternity surveys from 2007 and 2010. Outcomes were counts of women admitted for delivery of a baby and the percentage of women rating their care positively in 2007 and 2010.
Results
Hospitals publicised as providing the best maternity care in England had fewer admissions annually and lower occupancy rates (63.0% vs. 77.3%; p=0.09) than the national comparison group. Hospitals publicised as providing the worst maternity care were predominantly in the greater London area, with more women aged 15-34 years in their catchment areas than the national comparison group. There was no statistically significant change in overall maternity admissions in the best hospitals (+ 2.2%, p=0.40 at six months), or the worst hospitals (- 2.8%, p=0.49 at six months) during any period in the thirty-six months after public reporting relative to baseline. Compared to the national comparison group the worst rated hospitals experienced greater improvements in perceived quality after public reporting but these findings were not maintained in the matched analysis.
Conclusions
High profile public reporting of maternity care in England was not associated with changes in the utilisation of maternity services or improvements in patient reported quality. These findings provide further evidence that public reporting is unlikely to drive major improvements in health system performance through the mechanism of patient choice
The OpenPMU Platform for Open Source Phasor Measurements
OpenPMU is an open platform for the development of phasor measurement unit (PMU) technology. A need has been identified for an open-source alternative to commercial PMU devices tailored to the needs of the university researcher and for enabling the development of new synchrophasor instruments from this foundation. OpenPMU achieves this through open-source hardware design specifications and software source code, allowing duplicates of the OpenPMU to be fabricated under open-source licenses. This paper presents the OpenPMU device based on the Labview development environment. The device is performance tested according to the IEEE C37.118.1 standard. Compatibility with the IEEE C37.118.2 messaging format is achieved through middleware which is readily adaptable to other PMU projects or applications. Improvements have been made to the original design to increase its flexibility. A new modularized architecture for the OpenPMU is presented using an open messaging format which the authors propose is adopted as a platform for PMU research.</p
Antimicrobial Efficacy of an Innovative Emulsion of Medium Chain Triglycerides against Canine and Feline Periodontopathogens
Self-assembling Ultrashort NSAID-Peptide Nanosponges: Multifunctional Antimicrobial and Anti-inflammatory Materials
This paper outlines the design, synthesis and characterisation of innovative NSAID-peptide gelators which demonstrate antimicrobial and anti-inflammatory properties and have potential use as multifunctional materials for biomedical applications.</p
Principal Component Analysis of Wide Area Phasor Measurements for Islanding Detection – A Geometric View
This paper presents a new technique for the detectionof islanding conditions in electrical power systems. This problem isespecially prevalent in systems with significant penetrations of distributedrenewable generation. The proposed technique is based onthe application of principal component analysis (PCA) to data setsof wide-area frequency measurements, recorded by phasor measurementunits. The PCA approach was able to detect islandingaccurately and quickly when compared with conventional RoCoFtechniques, as well as with the frequency difference and change-ofangledifference methods recently proposed in the literature. Thereliability and accuracy of the proposed PCA approach is demonstratedby using a number of test cases, which consider islandingand nonislanding events. The test cases are based on real data,recorded from several phasor measurement units located in theU.K. power system
- …
