3,840 research outputs found
Integral throat entrance development, qualification and production for the Antares 3 nozzle
Although design analyses of a G-90 graphite integral throat entrance for the Antares 3 solid rocket motor nozzle indicated acceptable margins of safety, the nozzle throat insert suffered a thermostructural failure during the first development firing. Subsequent re-analysis using properties measured on material from the same billet as the nozzle throat insert showed negative margins. Carbon-carbon was investigated and found to result in large positive margins of safety. The G-90 graphite was replaced by SAI fast processed 4-D material which uses Hercules HM 10000 fiber as the reinforcement. Its construction allows powder filling of the interstices after preform fabrication which accelerates the densification process. Allied 15V coal tar pitch is then used to complete densification. The properties were extensively characterized on this material and six nozzles were subjected to demonstration, development and qualification firings
An Investigation Into the Causes of Building Cracks on the Rear Scarp of a Major Landslip
The paper concerns a building constructed on the rear scarp of a major lands lip in the London Clay. Since its construction, the structure has shown significant cracking which has worsened with time. The paper describes how, using a systematic process of observation and interpretation, the principal cause of cracking was eventually identified. This case history is of value to engineers as a cautionary tale in which the most obvious answer is not necessarily the correct one
The Changing Role of Pharmacists as Evidenced by the Strong Vocational Interest Blank
The Strong Vocational Interest Blank/Strong Campbell Interest Inventory-Merged Form, or simply Strong Vocational Interest Blank (SVIB), is widely used to determine the suitability of a student\u27s interests to a particular field. In the process of norming the instrument, data concerning the satisfaction of practitioners of a field and their responses on the instrument are gathered. Such data lend themselves to analysis of trends in the characteristics of those practitioners both over time and over the satisfaction spectrum. Hence changes in the field and characteristics lending themselves to satisfaction can be ascertained
Foundation Design and Construction for a Large Mill Complex
Very little good field data exists concerning the performance of heavily loaded end-bearing piles on thin layers of weak rock. The problems associated with the foundations for silos are often severe, since loads are normally heavy, and allowable differential settlements are often very small. The paper describes just such problems, associated with the construction of a flour mill complex, where the principal problems were associated with the uncertainties of pile performance. On the basis of the uniaxial unconfined compressive strength of the supporting rock the end-bearing piles supporting silos within the mill appeared to be overloaded. A programme of slow maintained load pile tests demonstrated that the piles in fact performed very well. Long term settlement records of the loaded structure have confirmed this
A decade of ejecta dust formation in the Type IIn SN 2005ip
In order to understand the contribution of core-collapse supernovae to the
dust budget of the early universe, it is important to understand not only the
mass of dust that can form in core-collapse supernovae but also the location
and rate of dust formation. SN 2005ip is of particular interest since dust has
been inferred to have formed in both the ejecta and the post-shock region
behind the radiative reverse shock. We have collated eight optical archival
spectra that span the lifetime of SN 2005ip and we additionally present a new
X-shooter optical-near-IR spectrum of SN 2005ip at 4075d post-discovery. Using
the Monte Carlo line transfer code DAMOCLES, we have modelled the blueshifted
broad and intermediate width H, H and He I lines from 48d to
4075d post-discovery using an ejecta dust model. We find that dust in the
ejecta can account for the asymmetries observed in the broad and intermediate
width H, H and He I line profiles at all epochs and that it is
not necessary to invoke post-shock dust formation to explain the blueshifting
observed in the intermediate width post-shock lines. Using a Bayesian approach,
we have determined the evolution of the ejecta dust mass in SN 2005ip over 10
years presuming an ejecta dust model, with an increasing dust mass from
~10 M at 48d to a current dust mass of 0.1 M.Comment: Accepted by MNRAS, 17 pages, 11 figures. Author accepted manuscript.
Accepted on 04/03/19. Deposited on 07/03/1
Understanding parental hesitancy toward children's COVID-19 vaccinations: The influence of government, media and interpersonal communication
In March 2022, the UK Health Security Agency and the National Health Service issued guidance for parents of children aged 5–11 concerning vaccinations. The guidance stated that parents of all children in this age bracket should be offered the chance to have their child vaccinated and that the procedure was particularly important for children who have health conditions that put them at high risk. However, expressions of child vaccine hesitancy rose steeply in the UK at the start of 2022 with 35.4% of primary school parents saying they were unlikely to vaccinate their children. Vaccination programmes are part of the global strategy for mitigating the effects of coronavirus disease, but their effectiveness is reliant upon high levels of uptake and administration. Vaccine hesitancy, for children in particular is an important concern, given that children can play a major role in coronavirus transmission within both families and schools. Listening to parental perspectives regarding the decision-making processes for vaccinating this age group, becomes fundamental in understanding childhood vaccine intentions. Through the analysis of semi-structured interviews, this paper is able to reveal detailed qualitative insights into the thoughts of UK parents and their attitudes toward children's vaccinations that quantitative statistics are otherwise unable to show. In the following article, we have identified a triangular relationship between government, media and interpersonal communication in shaping parental perspectives, leading to a mixture of both “pro-vax” and “anti-vax” attitudes [often simultaneously] in regards to the vaccination or non-vaccination of children. Our data provides original findings that will inform both policymakers and practitioners, building upon and extending the existing vaccination literature, furthering current debate and guiding future research
New Uses of Screens in Post-Lockdown Britain - Study Report and Findings
The ‘New Uses of Screens in Post-Lockdown Britain’ study (NUSPB) set out to discover the current lived experiences of British people and how screen technologies may or may not have become more permanently integrated within their day-to-day lives following the coronavirus lockdowns of 2020-2021
FLUORESCENCE STUDIES ON PHOTOSYNTHETIC PIGMENT DEVELOPMENT IN RHODOPSEUDOMONAS SPHEROIDES * , †
When bleached, aerobically grown cells of Rhodopseudomonas spheroides are transferred to semi-aerobic conditions to induce bacteriochlorophyll synthesis, a new fluorescence band, with a maximum at 790 nm, is observed in addition to the 885 nm emission maximum normally seen in pigmented cells. The 790 nm fluorescence may be due to bacterio-chlorophyll which has not been bound into the chromatophore membrane. The quantum yield of the 885 nm fluorescence is at first relatively high and then, about 1 hour after transfer, drops to the level found in pigmented photosynthetic cells. The coupling to the rest of the photo-synthetic apparatus, as indicated by the effect of dithionite on the fluorescence, also seems to occur during the first hour of pigment development, which suggests that the onset of fluorescence quenching is due at least in part to the synthesis of photochemical reaction centers. Continuation of these studies should provide new information on the formation, structure and molecular interactions of the pigments and the photosynthetic membranes.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/73322/1/j.1751-1097.1968.tb08021.x.pd
Quantifying atrial anatomy uncertainty from clinical data and its impact on electro-physiology simulation predictions
Patient-specific computational models of structure and function are increasingly being used to diagnose disease and predict how a patient will respond to therapy. Models of anatomy are often derived after segmentation of clinical images or from mapping systems which are affected by image artefacts, resolution and contrast. Quantifying the impact of uncertain anatomy on model predictions is important, as models are increasingly used in clinical practice where decisions need to be made regardless of image quality. We use a Bayesian probabilistic approach to estimate the anatomy and to quantify the uncertainty about the shape of the left atrium derived from Cardiac Magnetic Resonance images. We show that we can quantify uncertain shape, encode uncertainty about the left atrial shape due to imaging artefacts, and quantify the effect of uncertain shape on simulations of left atrial activation times
Dust Production and Particle Acceleration in Supernova 1987A Revealed with ALMA
Supernova (SN) explosions are crucial engines driving the evolution of
galaxies by shock heating gas, increasing the metallicity, creating dust, and
accelerating energetic particles. In 2012 we used the Atacama Large
Millimeter/Submillimeter Array to observe SN 1987A, one of the best-observed
supernovae since the invention of the telescope. We present spatially resolved
images at 450um, 870um, 1.4mm, and 2.8mm, an important transition wavelength
range. Longer wavelength emission is dominated by synchrotron radiation from
shock-accelerated particles, shorter wavelengths by emission from the largest
mass of dust measured in a supernova remnant (>0.2Msun). For the first time we
show unambiguously that this dust has formed in the inner ejecta (the cold
remnants of the exploded star's core). The dust emission is concentrated to the
center of the remnant, so the dust has not yet been affected by the shocks. If
a significant fraction survives, and if SN 1987A is typical, supernovae are
important cosmological dust producers.Comment: ApJL accepte
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