2,938 research outputs found
Statistical reproducibility of meta-analysis research claims for medical mask use in community settings to prevent COVID infection
The coronavirus pandemic (COVID) has been an exceptional test of current
scientific evidence that inform and shape policy. Many US states, cities, and
counties implemented public orders for mask use on the notion that this
intervention would delay and flatten the epidemic peak and largely benefit
public health outcomes. P-value plotting was used to evaluate statistical
reproducibility of meta-analysis research claims of a benefit for medical
(surgical) mask use in community settings to prevent COVID infection. Eight
studies (seven meta-analyses, one systematic review) published between 1
January 2020 and 7 December 2022 were evaluated. Base studies were randomized
control trials with outcomes of medical diagnosis or laboratory-confirmed
diagnosis of viral (Influenza or COVID) illness. Self-reported viral illness
outcomes were excluded because of awareness bias. No evidence was observed for
a medical mask use benefit to prevent viral infections in six p-value plots
(five meta-analyses and one systematic review). Research claims of no benefit
in three meta-analyses and the systematic review were reproduced in p-value
plots. Research claims of a benefit in two meta-analyses were not reproduced in
p-value plots. Insufficient data were available to construct p-value plots for
two meta-analyses because of overreliance on self-reported outcomes. These
findings suggest a benefit for medical mask use in community settings to
prevent viral, including COVID infection, is unproven.Comment: 21 pages, 100 references, 3 appendice
Velocity measurements for a solar active region fan loop from Hinode/EIS observations
The velocity pattern of a fan loop structure within a solar active region
over the temperature range 0.15-1.5 MK is derived using data from the EUV
Imaging Spectrometer (EIS) on board the Hinode satellite. The loop is aligned
towards the observer's line-of-sight and shows downflows (redshifts) of around
15 km/s up to a temperature of 0.8 MK, but for temperatures of 1.0 MK and above
the measured velocity shifts are consistent with no net flow. This velocity
result applies over a projected spatial distance of 9 Mm and demonstrates that
the cooler, redshifted plasma is physically disconnected from the hotter,
stationary plasma. A scenario in which the fan loops consist of at least two
groups of "strands" - one cooler and downflowing, the other hotter and
stationary -- is suggested. The cooler strands may represent a later
evolutionary stage of the hotter strands. A density diagnostic of Mg VII was
used to show that the electron density at around 0.8 MK falls from 3.2 x 10^9
cm^-3 at the loop base, to 5.0 x 10^8 cm^-3 at a projected height of 15 Mm. A
filling factor of 0.2 is found at temperatures close to the formation
temperature of Mg VII (0.8 MK), confirming that the cooler, downflowing plasma
occupies only a fraction of the apparent loop volume. The fan loop is rooted
within a so-called "outflow region" that displays low intensity and blueshifts
of up to 25 km/s in Fe XII 195.12 A (formed at 1.5 MK), in contrast to the
loop's redshifts of 15 km/s at 0.8 MK. A new technique for obtaining an
absolute wavelength calibration for the EIS instrument is presented and an
instrumental effect, possibly related to a distorted point spread function,
that affects velocity measurements is identified.Comment: 42 pages, 15 figures, submitted to Ap
Association between preseason training and performance in elite Australian football
Purpose: To examine the association between preseason training variables and subsequent in-season performance in an elite Australian football team.
Methods: Data from 41 elite male Australian footballers (mean [SD] age = 23.4 [3.1] y, height =188.4 [7.1] cm, and mass = 86.7 [7.9] kg) were collected from 1 Australian Football League (AFL) club. Preseason training data (external load, internal load, fitness testing, and session participation) were collected across the 17-wk preseason phase (6 and 11 wk post-Christmas). Champion Data© Player Rank (CDPR), coaches’ ratings, and round 1 selection were used as in-season performance measures. CDPR and coaches’ ratings were examined over the entire season, first half of the season, and the first 4 games. Both Pearson and partial (controlling for AFL age) correlations were calculated to assess if any associations existed between preseason training variables and in-season performance measures. A median split was also employed to differentiate between higher- and lower-performing players for each performance measure.
Results: Preseason training activities appeared to have almost no association with performance measured across the entire season and the first half of the season. However, many preseason training variables were significantly linked with performance measured across the first 4 games. Preseason training variables that were measured post-Christmas were the most strongly associated with in-season performance measures. Specifically, total on-field session rating of perceived exertion post-Christmas, a measurement of internal load, displayed the greatest association with performance.
Conclusion: Late preseason training (especially on-field match-specific training) is associated with better performance in the early season
Statistical reliability of meta_analysis research claims for gas stove cooking_childhood respiratory health associations
Odds ratios or p_values from individual observational studies can be combined
to examine a common cause_effect research question in meta_analysis. However,
reliability of individual studies used in meta_analysis should not be taken for
granted as claimed cause_effect associations may not reproduce. An evaluation
was undertaken on meta_analysis of base papers examining gas stove cooking,
including nitrogen dioxide, NO2, and childhood asthma and wheeze associations.
Numbers of hypotheses tested in 14 of 27 base papers, 52 percent, used in
meta_analysis of asthma and wheeze were counted. Test statistics used in the
meta_analysis, 40 odds ratios with 95 percent confidence limits, were converted
to p_values and presented in p_value plots. The median and interquartile range
of possible numbers of hypotheses tested in the 14 base papers was 15,360,
6,336_49,152. None of the 14 base papers made mention of correcting for
multiple testing, nor was any explanation offered if no multiple testing
procedure was used. Given large numbers of hypotheses available, statistics
drawn from base papers and used for meta-analysis are likely biased. Even so,
p-value plots for gas stove_current asthma and gas stove_current wheeze
associations show randomness consistent with unproven gas stove harms. The
meta-analysis fails to provide reliable evidence for public health policy
making on gas stove harms to children in North America. NO2 is not established
as a biologically plausible explanation of a causal link with childhood asthma.
Biases_multiple testing and p-hacking_cannot be ruled out as explanations for a
gas stove_current asthma association claim. Selective reporting is another bias
in published literature of gas stove_childhood respiratory health studies.
Keywords gas stove, asthma, meta-analysis, p-value plot, multiple testing,
p_hackingComment: International Journal of Statistics and Probability (2023
Robust Tensioned Kevlar Suspension Design
One common but challenging problem in cryogenic engineering is to produce a mount that has excellent thermal isolation but is also rigid. Such mounts can be achieved by suspending the load from a network of fibers or strings held in tension. Kevlar fibers are often used for this purpose owing to their high strength and low thermal conductivity. A suite of compact design elements has been developed to improve the reliability of suspension systems made of Kevlar
Birmingham Urban Climate Laboratory - A high density, urban meteorological dataset, from 2012 -2014
There is a paucity of urban meteorological observations worldwide, hindering progress in understanding and mitigating urban meteorological hazards and extremes. High quality urban datasets are required to monitor the impacts of climatological events, whilst providing data for evaluation of numerical models. The Birmingham Urban Climate Laboratory was established as an exemplar network to meet this demand for urban canopy layer observations. It comprises of an array of 84 wireless air temperature sensors nested within a coarser array of 24 automatic weather stations, with observations available between June 2012 and December 2014. data routinely underwent quality control, follows the ISO 8601 naming format and benefits from extensive site metadata. The data have been used to investigate the structure of the urban heat island in Birmingham and its associated societal and infrastructural impacts. The network is now being repurposed into a testbed for the assessment of crowd-sourced and satellite data, but the original dataset is now available for further analysis, and an open invitation is extended for its academic use
Soft X-ray coronal spectra at low activity levels observed by RESIK
The quiet-Sun X-ray emission is important for deducing coronal heating
mechanisms, but it has not been studied in detail since the Orbiting Solar
Observatory (OSO) spacecraft era. Bragg crystal spectrometer X-ray observations
have generally concentrated on flares and active regions. The high sensitivity
of the RESIK (REntgenovsky Spectrometer s Izognutymi Kristalami) instrument on
the CORONAS-F solar mission has enabled the X-ray emission from the quiet
corona to be studied in a systematic way for the first time. Our aim is to
deduce the physical conditions of the non-flaring corona from RESIK line
intensities in several spectral ranges using both isothermal and multithermal
assumptions. We selected and analyzed spectra in 312 quiet-Sun intervals in
January and February 2003, sorting them into 5 groups according to activity
level. For each group, the fluxes in selected spectral bands have been used to
calculate values parameters for the best-fit that lead to a intensities
characteristic of each group. We used both isothermal and multitemperature
assumptions, the latter described by differential emission measure (DEM)
distributions. RESIK spectra cover the wavelength range (3.3-6.1 A). This
includes emission lines of highly ionized Si, S, Cl, Ar, and K, which are
suitable for evaluating temperature and emission measure, were used. The RESIK
spectra during these intervals of very low solar activity for the first time
provide information on the temperature structure of the quiet corona. Although
most of the emission seems to arise from plasma with a temperature between 2MK
and 3MK, there is also evidence of a hotter plasma (T approx. 10MK) with an
emission measure 3 orders smaller than the cooler component. Neither coronal
nor photospheric element abundances appear to describe the observed spectra
satisfactorily.Comment: Submitting 1 Latex and 7 figure file
The Relationship between Change of Direction Speed in the Frontal Plane, Power, Reactive Strength, and Strength
International Journal of Exercise Science 7(4) : 260-270, 2014. Change-of-direction speed (CODS) is an important quality to performance in multi-direction sports. The relationship between CODS in the frontal plane and power, strength, and reactive strength is largely unstudied. Twenty-three male college students participated in this study. The study used a Pearson’s product-moment correlation to measure the relationship between CODS, power, strength, and reactive strength. A lateral shuffle test was used as the measure of CODS. A lateral hop for distance was used as the measure of power in the frontal plane. A countermovement vertical jump test was used as the measure of power in the sagittal plane. A depth jump was used as the measure of reactive strength in the sagittal plane. A 3RM squat test was used as the measure of strength. There was a moderate relationship between the lateral shuffle test and the lateral hop (r =.541, p = .008 and r =.567, p = .005), but no significant relationships with the countermovement vertical jump, depth jump, or squat test. These results suggest that power should be trained in all planes to improve CODS performance in multi-direction sports, and that CODS should be trained in its sport-specific context
The reliability and sensitivity of performance measures in a novel pace bowling test
Objectives: To evaluate the reliability and sensitivity of performance measures in a novel pace-bowling test. Methods: Thirteen male amateur-club fast bowlers completed a novel pace-bowling test on 2 separate occasions, 4–7 d apart. Participants delivered 48 balls (8 overs) at 5 targets on a suspended sheet situated behind a live batter, who stood in a right-handed and left-handed stance for an equal number of deliveries. Delivery instruction was frequently changed, with all deliveries executed in a preplanned sequence. Data on ball-release speed were captured by radar gun. A high-speed camera captured the moment of ball impact on the target sheet for assessment of radial error and bivariate variable error. Delivery rating of perceived exertion (0–100%) was collected as a measure of intensity. Results: Intraclass correlation coefficients and coefficients of variation revealed excellent reliability for peak and mean ball-release speed, acceptable reliability for delivery rating of perceived exertion, and poor reliability for mean radial error, bivariate variable error, and variability of ball-release speed. The smallest worthwhile change indicated high sensitivity with peak and mean ball-release speed and lower sensitivity with mean radial error and bivariate variable error. Conclusions: The novel pace-bowling test incorporates improvements in ecological validity compared with its predecessors and can be used to provide a more comprehensive evaluation of pace-bowling performance. Data on the smallest worthwhile change can improve interpretation of pace-bowling research findings and may therefore influence recommendations for applied practice. © 2018 Human Kinetics, Inc
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The Birmingham Urban Climate Laboratory: an open meteorological test bed and challenges of the smart city
Existing urban meteorological networks have an important role to play as test beds for inexpensive and more sustainable measurement techniques that are now becoming possible in our increasingly smart cities. The Birmingham Urban Climate Laboratory (BUCL) is a near-real-time, high-resolution urban meteorological network (UMN) of automatic weather stations and inexpensive, nonstandard air temperature sensors. The network has recently been implemented with an initial focus on monitoring urban heat, infrastructure, and health applications. A number of UMNs exist worldwide; however, BUCL is novel in its density, the low-cost nature of the sensors, and the use of proprietary Wi-Fi networks. This paper provides an overview of the logistical aspects of implementing a UMN test bed at such a density, including selecting appropriate urban sites; testing and calibrating low-cost, nonstandard equipment; implementing strict quality-assurance/quality-control mechanisms (including metadata); and utilizing preexisting Wi-Fi networks to transmit data. Also included are visualizations of data collected by the network, including data from the July 2013 U.K. heatwave as well as highlighting potential applications. The paper is an open invitation to use the facility as a test bed for evaluating models and/or other nonstandard observation techniques such as those generated via crowdsourcing techniques
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