3,848 research outputs found
Magnetic fields and differential rotation on the pre-main sequence
Maps of magnetic field topologies of rapidly rotating stars obtained over the last decade or so have provided unique insight into the operation of stellar dynamos. However, for solar-type stars many of the targets imaged to date have been lower-mass zero-age main sequence stars. We present magnetic maps and differential rotation measurements of two-higher mass pre-main sequence stars HD 106506 (~10 Myrs) and HD 141943 (~15 Myrs). These stars should evolve into mid/late F-stars with predicted high differential rotation and little magnetic activity. We investigate what effect the extended convection zones of these pre-main sequence stars has on their differential rotation and magnetic topologies. ©2009 American Institute of Physic
Quantitative Bioprocess Containment Validation
The safe use of genetically modified micro-organisms (GMMOs) for the industrial manufacture of therapeutic and other products depends on the design, implementation and validation of effective containment principles. This project has established a test method that can generate quantitative data on bioprocess releases that can be used to validate the containment of bioprocess equipment. A standard tracer gas leak test has been correlated with a quantitative polymerase chain reaction (QPCR) assay for the detection of GMMOs. The QPCR assay for Escherichia coli RV308 pHKY531 has been shown to be specific and have a low limit of detection (less than 50 cells in 10 μL) with a range of 6 orders of magnitude and an error of ± 0.11 logs. This assay has been used to analyse bioaerosol samples collected by an Aerojet General Cyclone. Throughout the course of the project, work has been carried out to improve the collection efficiency of a cyclone sampler and to investigate the effects of various approaches to bioaerosol sampling in a process environment. Using this method a good correlation has been observed between the spatial location of the release point and the collection efficiency of the cyclone. The release of aerosols from leaks in bioprocess equipment has been simulated by capillary tubes of various diameters and lengths. From the data presented here a value below 6 x 10
-6 cm min-1 SF6 would be recommended for an acceptable level for apiece of bioprocess equipment at a differential pressure of 2 bar. For a 5 mm leak this value is equivalent to a 3 μm diameter hole, which has been shown not to transmit a suspension of micro-organisms. The implications of these findings are discussed in relation to the validation of bioprocess containment
Wettability-independent droplet transport by \emph{Bendotaxis}
We demonstrate \textit{bendotaxis}, a novel mechanism for droplet
self-transport at small scales. A combination of bending and capillarity in a
thin channel causes a pressure gradient that, in turn, results in the
spontaneous movement of a liquid droplet. Surprisingly, the direction of this
motion is always the same, regardless of the wettability of the channel. We use
a combination of experiments at a macroscopic scale and a simple mathematical
model to study this motion, focussing in particular on the time scale
associated with the motion. We suggest that \emph{bendotaxis} may be a useful
means of transporting droplets in technological applications, for example in
developing self-cleaning surfaces, and discuss the implications of our results
for such applications.Comment: 5 pages, 4 figures. Supplementary Information available on reques
Moisture Degradation of CTD-403: Testing the Application of Cyanate Ester Insulations to Fusion Devices
The fusion devices currently being developed present several challenges for magnet designers. One challenge lies within the electrical insulation, which must be able to withstand extreme temperatures (both cryogenic and elevated temperatures), large shear and compressive stresses, high operating voltages, and high levels of incident radiation. To address the need for better performing insulation systems, Composite Technology Development, Inc. (CTD) has developed CTD-403, a cyanate ester resin with increased radiation resistance, ease of processing and fabrication, low moisture absorption characteristics, and high mechanical and electrical strength at cryogenic and elevated temperatures.
In this thesis, CTD-403 resin based insulation systems were tested under the operation guidelines of the Quasi-Poloidal Stellarator (QPS). Because the coils of QPS are water cooled, it is important to understand the effects of long term humidity exposure on the insulation. The effects of humidity on moisture absorption characteristics, dimensional stability, mechanical and electrical properties were characterized. Increasing the humidity level caused a corresponding increase in the saturation level, while increasing the temperature of exposure magnified these effects causing more pronounced non-Fickian behavior. The mechanical properties degraded with an increase in humidity level. Elevated temperature effects are more pronounced on the compressive properties than the tensile properties. The glass transition temperature was more greatly affected by elevated temperature exposure as opposed to increased humidity exposure, decreasing in both instances. The dielectric strength decreases with increased humidity level and exposure time.
Based on these findings, the performance of cyanate ester resin based insulation systems is shown superior to that of traditional epoxy based resin systems in all performance measures. The degradation of the mechanical and electrical properties of the insulation from long term effects of humidity and elevated temperature exposure are shown to be within the performance criteria bounds, and the insulation is therefore recommended for use in current and future fusion programs
Model Agnostic Saliency for Weakly Supervised Lesion Detection from Breast DCE-MRI
There is a heated debate on how to interpret the decisions provided by deep
learning models (DLM), where the main approaches rely on the visualization of
salient regions to interpret the DLM classification process. However, these
approaches generally fail to satisfy three conditions for the problem of lesion
detection from medical images: 1) for images with lesions, all salient regions
should represent lesions, 2) for images containing no lesions, no salient
region should be produced,and 3) lesions are generally small with relatively
smooth borders. We propose a new model-agnostic paradigm to interpret DLM
classification decisions supported by a novel definition of saliency that
incorporates the conditions above. Our model-agnostic 1-class saliency detector
(MASD) is tested on weakly supervised breast lesion detection from DCE-MRI,
achieving state-of-the-art detection accuracy when compared to current
visualization methods
Our Day Out
This paper presents the findings of the Our Day Out project which engaged older
peoples’ groups across Merseyside in collecting and sharing memories of days
out to the British seaside. Central to project design was the use of images from
the Keith Medley Archive, held by Liverpool John Moores University’s Special
Collections. The project aimed to add context and meaning to a selection of
Medley images which documented day trippers during the 1960s to New
Brighton, a popular pre and post Second World War day trip destination for
communities around Merseyside. The photographs were used to instigate
discussions within memory workshops, which were recorded and shared on the
website http://www.our-day-out.co.uk/.
The selected Medley images were from a special place that took its visitors out of
their everyday environment and presented opportunities for fun and recreation.
The memory workshops conducted for Our Day Out took participants back in
time to a place that involved escapism and amusement. This study found that the
images acted as an effective point of departure for building an online collection of
stories about social practices at the British Seaside in the 1960s. Furthermore, the
study found that older peoples’ well -being benefitted from discussing times
when they were free of physical restriction and from when they held fond and
happy memories.
This paper discusses the value of archived photographs as instigators for creating
digital stories with and by older people. Also considered is the role of nostalgia
in reminiscence and memory work.info:eu-repo/semantics/publishedVersio
Pre and Post-hoc Diagnosis and Interpretation of Malignancy from Breast DCE-MRI
We propose a new method for breast cancer screening from DCE-MRI based on a
post-hoc approach that is trained using weakly annotated data (i.e., labels are
available only at the image level without any lesion delineation). Our proposed
post-hoc method automatically diagnosis the whole volume and, for positive
cases, it localizes the malignant lesions that led to such diagnosis.
Conversely, traditional approaches follow a pre-hoc approach that initially
localises suspicious areas that are subsequently classified to establish the
breast malignancy -- this approach is trained using strongly annotated data
(i.e., it needs a delineation and classification of all lesions in an image).
Another goal of this paper is to establish the advantages and disadvantages of
both approaches when applied to breast screening from DCE-MRI. Relying on
experiments on a breast DCE-MRI dataset that contains scans of 117 patients,
our results show that the post-hoc method is more accurate for diagnosing the
whole volume per patient, achieving an AUC of 0.91, while the pre-hoc method
achieves an AUC of 0.81. However, the performance for localising the malignant
lesions remains challenging for the post-hoc method due to the weakly labelled
dataset employed during training.Comment: Submitted to Medical Image Analysi
Putting the Boom, Boom, Boom into Physical Activity and Health: Music Festivals as a Positive Health Alternative to Couch Fandom
Background: Despite the popularity of outdoor music festivals in the UK, no evidence exists of the volume or intensity of movement that occurs through attendance at these festivals and the potential health benefits this may provide. The aim of this study was to accurately record the amount of physical activity and movement at the Glastonbury Festival and to compare it against recommended levels. Methods: 22 attendees wore an Actigraph activity monitor and GPS data-logger to the Glastonbury Festival. Distances travelled, speeds and durations were recorded. Activity levels were identified based on step count thresholds and the total duration spent in moderate to vigorous physical activity (MVPA) was calculated. Results: Mean total distance of 66.1 km was recorded with daily distance (11.01 km), movement duration (11 h 28 min) and steps/day (15,661). Total MVPA of 927 min occurred over the festival period. Conclusions: This study objectively recorded the volume of physical activity that occurred at an outdoor UK festival. Large movement distances and MVPA six times greater than the recommended guidelines for health benefits were found. It can be suggested that attendance at large-scale festivals can be used as a modality for attaining physical activity guidelines alongside commonly suggested fitness activitie
Bonding with Self-etching Primers – Pumice or Pre-etch? An \u3cem\u3ein vitro\u3c/em\u3e Study
The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (±1 SD) for groups 1–4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs
Bonding with Self-etching Primers – Pumice or Pre-etch? An \u3cem\u3ein vitro\u3c/em\u3e Study
The purpose of this study was to compare the shear bond strengths (SBSs) of orthodontic brackets bonded with self-etching primer (SEP) using different enamel surface preparations. A two-by-two factorial study design was used. Sixty human premolars were harvested, cleaned, and randomly assigned to four groups (n = 15 per group). Teeth were bathed in saliva for 48 hours to form a pellicle. Treatments were assigned as follows: group 1 was pumiced for 10 seconds and pre-etched for 5 seconds with 37 per cent phosphoric acid before bonding with SEP (Transbond Plus). Group 2 was pumiced for 10 seconds before bonding. Group 3 was pre-etched for 5 seconds before bonding. Group 4 had no mechanical or chemical preparation before bonding. All teeth were stored in distilled water for 24 hours at 37°C before debonding. The SBS values and adhesive remnant index (ARI) score were recorded. The SBS values (±1 SD) for groups 1–4 were 22.9 ± 6.6, 16.1 ± 7.3, 36.2 ± 8.2, and 13.1 ± 10.1 MPa, respectively. Two-way analysis of variance and subsequent contrasts showed statistically significant differences among treatment groups. ARI scores indicated the majority of adhesive remained on the bracket for all four groups. Pre-etching the bonding surface for 5 seconds with 37 per cent phosphoric acid, instead of pumicing, when using SEPs to bond orthodontic brackets, resulted in greater SBSs
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