4,847 research outputs found
Relaxation Design of Separable Tube Connectors
Design procedure to predict relaxation or time to leakage for separable tube connector
In-vivo magnetic resonance imaging of hyperpolarized silicon particles
Silicon-based micro and nanoparticles have gained popularity in a wide range
of biomedical applications due to their biocompatibility and biodegradability
in-vivo, as well as a flexible surface chemistry, which allows drug loading,
functionalization and targeting. Here we report direct in-vivo imaging of
hyperpolarized 29Si nuclei in silicon microparticles by MRI. Natural physical
properties of silicon provide surface electronic states for dynamic nuclear
polarization (DNP), extremely long depolarization times, insensitivity to the
in-vivo environment or particle tumbling, and surfaces favorable for
functionalization. Potential applications to gastrointestinal, intravascular,
and tumor perfusion imaging at sub-picomolar concentrations are presented.
These results demonstrate a new background-free imaging modality applicable to
a range of inexpensive, readily available, and biocompatible Si particles.Comment: Supplemental Material include
Evaluation of Salmon (<i>Salmo salar</i>) and Rainbow Trout (<i>Oncorhynchus mykiss</i>) pin bones using textural analysis and micro X-ray computational tomography
Industrially, common problems arise with the deboning pin bone process, where Atlantic Salmon (Salmo salar) and Rainbow Trout (Oncorhynchus mykiss) fillets, post rigor, are subjected to a pulling process to remove the pin bones from the fillet. This study measured the length of pin bones from two species of fish and two different industrial graded weights, and then used a texture analyser and lCT X-ray to measure the pulling force, break point and volume of the pin bones of both species of fish. Results showed that salmon pin bones required significantly higher pulling force to remove pin bones from the fish fillet when compared with Trout pin bones. Interestingly Trout pin bones were significantly longer and stronger than Salmon pin bones, but had significantly lower volume. This research has progressed the issues surrounding pin boning industrially, however, more studies are required in order to understand if these differences affect the overall deboning pin bone process
A trap-based pulsed positron beam optimised for positronium laser spectroscopy
We describe a pulsed positron beam that is optimised for positronium (Ps) laser-spectroscopy experiments. The system is based on a two-stage Surko-type buffer gas trap that produces 4 ns wide pulses containing up to 5 Ă 105 positrons at a rate of 0.5-10 Hz. By implanting positrons from the trap into a suitable target material, a dilute positronium gas with an initial density of the order of 107 cmâ3 is created in vacuum. This is then probed with pulsed (ns) laser systems, where various Ps-laser interactions have been observed via changes in Ps annihilation rates using a fast gamma ray detector. We demonstrate the capabilities of the apparatus and detection methodology via the observation of Rydberg positronium atoms with principal quantum numbers ranging from 11 to 22 and the Stark broadening of the n = 2 â 11 transition in electric fields
The effect of collagenase, water and calcium chloride on the removal of <i>Salmo salar</i> (salmon) and <i>Oncorhynchus mykiss</i> (trout) pin bones
The aim of this study was to determine the influence of the fillet structure on the deboning force required to remove salmon and trout pin bones. Salmon and trout fillets with differing fillet structure were used, in order to study the importance of the fillet structure on the deboning process. In the first test naturally gaping and non-gaping fillets were compared. To confirm the role that the collagen plays within the fillet structure, the fillets underwent series of treatments. Fillets were put into (i) a collagenase solution to remove the collagen in the fillet (ii) a calcium chloride solution to determine if collagen was the main influential factor. Both treated salmon and trout fillets were again compared to untreated fillets from the same batch. The results indicate that collagenase and calcium chloride have a large interaction on deboning force compared to water or no treatments
Ring-fencing a budget for cancer drugs: is it fair?
Ring-fencing is defined as protecting funds for use in a specific area. In the NationalHealth Service in the UK, various methods to ring-fence cancer have beenemployed over the years; more recently the Cancer Drugs Fund in England hasenabled cancer drugs that would not normally be considered cost-effective to beprovided to patients. This has created variation in provision between England andthe devolved countries. While some would argue that ring-fencing allows majoradvances to be made in the treatment of a particular condition, others wouldargue that it is intrinsically unfair. In this debate, Graham and Cassidy have writtenan article arguing the affirmative position and Hughes and Duerden were invitedto respond directly to their arguments. As with all the RCPE's 'Currentcontroversies', the authors have been asked to take a deliberately polarisedposition and so the views they express may be somewhat overstated
PlagioclaseâSaturated Melt Hygrothermobarometry and PlagioclaseâMelt Equilibria Using Machine Learning
Compositions of plagioclaseâmelt pairs are commonly used to constrain temperatures (T), dissolved water contents (H2O) and pressures (P) of preâeruptive magma storage and transport. However, previous plagioclaseâbased thermometers, hygrometers, and barometers can have significant errors, leading to imprecise reconstructions of conditions during plagioclase growth. Here, we explore whether we can refine existing plagioclaseâbased hygrothermobarometers with either plagioclaseâmelt or meltâonly chemistry (±T/H2O), calibrated using random forest machine learning on experimental petrology data (n = 1,152). We find that both the plagioclaseâmelt and meltâonly models return similar crossâvalidation rootâmeanâsquare errors (RMSEs), as the melt holds most of the PâTâH2O information rather than the plagioclase. T/H2Oâdependent melt models have test set RMSEs of 25°C, 0.70 wt.% and 76 MPa for temperature, H2O content and pressure, respectively, while T/H2Oâindependent models have RMSEs of 38°C, 0.97 wt.% and 91 MPa. The melt thermometer and hygrometer are applicable to a wide range of plagioclaseâbearing melts at temperatures between 664 and 1355°C, and with H2O concentrations up to 11.2 wt.%, while the melt barometer is suitable for pressures of â€500 MPa. An updated plagioclaseâmelt equilibrium model has also been calibrated, allowing the equilibrium anorthite content to be predicted with an error of 5.8 mol%. The new PâTâH2OâAn models were applied to matrix glasses and melt inclusions from the 1980 Mount St Helens (USA) and 2014â2015 Holuhraun (Iceland) eruptions, corroborating previous independent estimates and observations. Models are available at https://github.com/kyraâcutler/PlagâsaturatedâmeltâPâTâH2OâAn, enabling assessment of plagioclaseâmelt equilibrium and characterization of lastâequilibrated PâTâH2O conditions of plagioclaseâsaturated magmas
Making mentoring work: The need for rewiring epistemology
To help produce expert coaches at both participation and performance levels, a number of governing bodies have established coach mentoring systems. In light of the limited literature on coach mentoring, as well as the risks of superficial treatment by coach education systems, this paper therefore critically discusses the role of the mentor in coach development, the nature of the mentor-mentee relationship and, most specifically, how expertise in the mentee may best be developed. If mentors are to be effective in developing expert coaches then we consequently argue that a focus on personal epistemology is required. On this basis, we present a framework that conceptualizes mentee development on this level through a step by step progression, rather than unrealistic and unachievable leap toward expertise. Finally, we consider the resulting implications for practice and research with respect to one-on-one mentoring, communities of practice, and formal coach education
Splitting fields and general differential Galois theory
An algebraic technique is presented that does not use results of model theory
and makes it possible to construct a general Galois theory of arbitrary
nonlinear systems of partial differential equations. The algebraic technique is
based on the search for prime differential ideals of special form in tensor
products of differential rings. The main results demonstrating the work of the
technique obtained are the theorem on the constructedness of the differential
closure and the general theorem on the Galois correspondence for normal
extensions..Comment: 33 pages, this version coincides with the published on
Analysis of the charging of the SCATHA (P78-2) satellite
The charging of a large object in polar Earth orbit was investigated in order to obtain a preliminary indication of the response of the shuttle orbiter to such an environment. Two NASCAP (NASA Charging Analyzer Program) models of SCATHA (Satellite Charging at High Altitudes) were used in simulations of charging events. The properties of the satellite's constituent materials were compiled and representations of the experimentally observed plasma spectra were constructed. Actual charging events, as well as those using test environments, were simulated. Numerical models for the simulation of particle emitters and detectors were used to analyze the operation of these devices onboard SCATHA. The effect of highly charged surface regions on the charging conductivity within a photosheath was used to interpret results from the onboard electric field experiment. Shadowing calculations were carried out for the satellite and a table of effective illuminated areas was compiled
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