1,637 research outputs found
Attitudes and Experiences of Preservice Teachers Utilizing Video Annotation Software: A Phenomenological Study
The purpose of this hermeneutic phenomenological study was to explore preservice teachers’ experiences with video observations at Central University. The theory guiding this study was Bandura’s self-efficacy theory as it provides insights into the internal and external factors that affect an individual’s perception of their capabilities. Self-efficacy is a critical component and goal of field experience observations. The central research question for this hermeneutic phenomenological study was: What are preservice teachers’ attitudes and experiences using video annotation software during field experience? The study was divided into two phases: individual interviews with preservice teachers, audio-visual elicitation interviews, a letter-writing activity, and qualitative data aggregation. Four themes were derived from the participants’ experiences: (a) streamlined reflection, (b) digital detachment, (c) the supervisor variable, and (d) program components’ effect on self-efficacy. Interpretations of the themes included four significant interpretations: (a) video annotation software improves reflection capabilities and personal agency, (b) video annotation software is a field supervision tool, not replacement, (c) convenient but not complete: video annotation software asynchronous communication is not enough, and (d) expectations and structure matter
Modelling of an anaerobic packed bed reactor used in processing of sugarcane vinasse to recover hydrogen using the anaerobic digestion model number 1
Espresso coffees, caffeine and chlorogenic acid intake: potential health implications
HPLC analysis of 20 commercial espresso coffees revealed 6-fold differences in caffeine levels, a 17-fold range of caffeoylquinic acid contents, and 4-fold differences in the caffeoylquinic acid:caffeine ratio. These variations reflect differences in batch-to-batch bean composition, possible blending of arabica with robusta beans, as well as roasting and grinding procedures, but the predominant factor is likely to be the amount of beans used in the coffee-making/barista processes. The most caffeine in a single espresso was 322 mg and a further three contained >200 mg, exceeding the 200 mg day−1 upper limit recommended during pregnancy by the UK Food Standards Agency. This snap-shot of high-street expresso coffees suggests the published assumption that a cup of strong coffee contains 50 mg caffeine may be misleading. Consumers at risk of toxicity, including pregnant women, children and those with liver disease, may unknowingly ingest excessive caffeine from a single cup of espresso coffee. As many coffee houses prepare larger volume coffees, such as Latte and Cappuccino, by dilution of a single or double shot of expresso, further study on these products is warranted. New data are needed to provide informative labelling, with attention to bean variety, preparation, and barista methods
Using bacterial biomarkers to identify early indicators of cystic fibrosis pulmonary exacerbation onset
Acute periods of pulmonary exacerbation are the single most important cause of morbidity in cystic fibrosis patients, and may be associated with a loss of lung function. Intervening prior to the onset of a substantially increased inflammatory response may limit the associated damage to the airways. While a number of biomarker assays based on inflammatory markers have been developed, providing useful and important measures of disease during these periods, such factors are typically only elevated once the process of exacerbation has been initiated. Identifying biomarkers that can predict the onset of pulmonary exacerbation at an early stage would provide an opportunity to intervene before the establishment of a substantial immune response, with major implications for the advancement of cystic fibrosis care. The precise triggers of pulmonary exacerbation remain to be determined; however, the majority of models relate to the activity of microbes present in the patient's lower airways of cystic fibrosis. Advances in diagnostic microbiology now allow for the examination of these complex systems at a level likely to identify factors on which biomarker assays can be based. In this article, we discuss key considerations in the design and testing of assays that could predict pulmonary exacerbations
Spectral Theory of Sparse Non-Hermitian Random Matrices
Sparse non-Hermitian random matrices arise in the study of disordered
physical systems with asymmetric local interactions, and have applications
ranging from neural networks to ecosystem dynamics. The spectral
characteristics of these matrices provide crucial information on system
stability and susceptibility, however, their study is greatly complicated by
the twin challenges of a lack of symmetry and a sparse interaction structure.
In this review we provide a concise and systematic introduction to the main
tools and results in this field. We show how the spectra of sparse
non-Hermitian matrices can be computed via an analogy with infinite dimensional
operators obeying certain recursion relations. With reference to three
illustrative examples --- adjacency matrices of regular oriented graphs,
adjacency matrices of oriented Erd\H{o}s-R\'{e}nyi graphs, and adjacency
matrices of weighted oriented Erd\H{o}s-R\'{e}nyi graphs --- we demonstrate the
use of these methods to obtain both analytic and numerical results for the
spectrum, the spectral distribution, the location of outlier eigenvalues, and
the statistical properties of eigenvectors.Comment: 60 pages, 10 figure
Hubble Space Telescope Survey of Interstellar ^12CO/^13CO in the Solar Neighborhood
We examine 20 diffuse and translucent Galactic sight lines and extract the
column densities of the ^12CO and ^13CO isotopologues from their ultraviolet
A--X absorption bands detected in archival Space Telescope Imaging Spectrograph
data with lambda/Deltalambda geq 46,000. Five more targets with Goddard
High-Resolution Spectrograph data are added to the sample that more than
doubles the number of sight lines with published Hubble Space Telescope
observations of ^13CO. Most sight lines have 12-to-13 isotopic ratios that are
not significantly different from the local value of 70 for ^12C/^13C, which is
based on mm-wave observations of rotational lines in emission from CO and H_2CO
inside dense molecular clouds, as well as on results from optical measurements
of CH^+. Five of the 25 sight lines are found to be fractionated toward lower
12-to-13 values, while three sight lines in the sample are fractionated toward
higher ratios, signaling the predominance of either isotopic charge exchange or
selective photodissociation, respectively. There are no obvious trends of the
^12CO-to-^13CO ratio with physical conditions such as gas temperature or
density, yet ^12CO/^13CO does vary in a complicated manner with the column
density of either CO isotopologue, owing to varying levels of competition
between isotopic charge exchange and selective photodissociation in the
fractionation of CO. Finally, rotational temperatures of H_2 show that all
sight lines with detected amounts of ^13CO pass through gas that is on average
colder by 20 K than the gas without ^13CO. This colder gas is also sampled by
CN and C_2 molecules, the latter indicating gas kinetic temperatures of only 28
K, enough to facilitate an efficient charge exchange reaction that lowers the
value of ^12CO/^13CO.Comment: 1-column emulateapj, 23 pages, 9 figure
The aerodynamic performance of a range of FIFA-approved footballs
Much discussion surrounds the flight of a football especially that perceived as irregular and is typically done so with little understanding of the aerodynamic effects or substantive evidence of the path taken. This work establishes that for a range of FIFA approved balls there is a significant variation in aerodynamic performance.
This paper describes the methods used for mounting stationary and spinning footballs in a wind tunnel enabling accurate force data to be obtained, and the analysis techniques used. The approach has been to investigate a number of scenarios: Non-spinning Reynolds Sweep, Unsteady Loads, Orientation Sensitivity (Yaw Sweep) and Spinning Reynolds Sweep. The techniques are applied to a number of footballs with differing constructions and the results reported. To put the aerodynamic data into context the results are applied in a flight model to predict the potential differences in the behaviour of each ball in the air.
The paper concludes that although the drag characteristics are different for the different balls tested the simulation suggests that this has only a limited effect on the flight of the ball. It is also shown that the unsteadiness of the aerodynamic loads is unlikely to be responsible for unpredictable behaviour. However, it is also shown that there are significant differences in the lateral aerodynamic forces for a range of FIFA approved match balls, and that these aerodynamic differences have a significant effect on the flight path for both spinning and for slowly rotating balls
The application of simulation to the understanding of football flight
This paper demonstrates the value of using a flight model in the analysis of the flight of a football, and explores the complexity
of the model required to produce useful results. Two specific aspects of the simulation are addressed: the need
to include a model of spin decay and the requirement to include a full aerodynamic drag profile as a function of Reynolds
number rather than a single indicative value. Both are aspects of the ball performance that are experimentally intensive
to obtain.
The simulated flights show that the inclusion of spin degradation is important if flight validation is the objective, but
that it may be unnecessary in a comparative study. The simple analytical model of spin degradation is shown to overestimate
the reduction in lateral deviation when compared to experimentally acquired data. Therefore, the experimental
method is preferred.
The analysis of the shape of the drag profile (drag coefficient against Reynolds number) is explored, and it is shown
from the simulated flights that post-critical coefficients of drag have the greatest effect on trajectories, and an average
drag value is sufficient for most modelled scenarios
Do Physical Activity and Aerobic Fitness Moderate the Association Between Birth Weight and Metabolic Risk in Youth?: The European Youth Heart Study
Mixed superposition rules and the Riccati hierarchy
Mixed superposition rules, i.e., functions describing the general solution of
a system of first-order differential equations in terms of a generic family of
particular solutions of first-order systems and some constants, are studied.
The main achievement is a generalization of the celebrated Lie-Scheffers
Theorem, characterizing systems admitting a mixed superposition rule. This
somehow unexpected result says that such systems are exactly Lie systems, i.e.,
they admit a standard superposition rule. This provides a new and powerful tool
for finding Lie systems, which is applied here to studying the Riccati
hierarchy and to retrieving some known results in a more efficient and simpler
way.Comment: 20 page
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