1,036 research outputs found
Hydrogen bonding in substituted nitroanilines : isolated nets in 1,3-diamino-4-nitrobenzene and continuously interwoven nets in 3,5-dinitroaniline
Peer reviewedPublisher PD
Compositional and shear strength characteristics of a spoil heap at Littleton colliery, Staffordshire
Since the Aberfan colliery spoil heap disaster the National Coal Board has sponsored a research programme on existing British spoil heaps. This thesis is part of that programme and considers an unburnt, unwashed, conical spoil heap at Littleton Colliery, Staffordshire. Tipping took place from about 1900 to about 1940 and records relating to discard constituents are very sparse. A slope failure in 1970 instigated this research project which is aimed at elucidating the compositional and shear strength characteristics affecting the stability of spoils in the Littleton area. Mineralogical, chemical and shear strength analyses were carried out on samples from the spoil heap and contributing underground measures. The absence of an underground measure from the original list of contributors was detected during the mineralogical and chemical analyses. This measure was identified, showing the value of such analyses in clarifying the history of such ancient tips. Mineralogy was found to correlate well with the chemical analyses of the samples, and the analyses of the spoil heap materials correlated well with those of the underground materials. No evidence of leaching or weathering was found in the tip. The shear strengths of the materials tested correlated well with the mineralogical and chemical analyses, the unusually low shear strengths of Littleton Spoil Heap No. 1 being reflected by high clay mineral contents. The slope stability problems occurring in the spoil heap are believed to be related to the Maclane Tippler method of spoil placement which has resulted in the spoil heap material approaching or achieving residual shear strength. A perched water-table within the spoil heap has initiated instability, giving rise to a deep-seated, circular slip
Spectroscopic Observations of Convective Patterns in the Atmospheres of Metal-Poor Stars
Convective line asymmetries in the optical spectrum of two metal-poor stars,
Gmb1830 and HD140283, are compared to those observed for solar metallicity
stars. The line bisectors of the most metal-poor star, the subgiant HD140283,
show a significantly larger velocity span that the expectations for a
solar-metallicity star of the same spectral type and luminosity class. The
enhanced line asymmetries are interpreted as the signature of the lower metal
content, and therefore opacity, in the convective photospheric patterns. These
findings point out the importance of three-dimensional convective velocity
fields in the interpretation of the observed line asymmetries in metal-poor
stars, and in particular, urge for caution when deriving isotopic ratios from
observed line shapes and shifts using one-dimensional model atmospheres.
The mean line bisector of the photospheric atomic lines is compared with
those measured for the strong Mg I b1 and b2 features. The upper part of the
bisectors are similar, and assuming they overlap, the bottom end of the
stronger lines, which are formed higher in the atmosphere, goes much further to
the red. This is in agreement with the expected decreasing of the convective
blue-shifts in upper atmospheric layers, and compatible with the high velocity
redshifts observed in the chromosphere, transition region, and corona of
late-type stars.Comment: 27 pages, LaTeX; 10 Figures (14 PostScript files); to be published in
The Astrophysical Journa
On-line partial discharge testing of some of the worst performing circuits on a utility distribution system
New Extremely Metal-Poor Stars in the Galactic Halo
We present a detailed abundance analysis based on high resolution and high
signal-to-noise spectra of eight extremely metal poor (EMP) stars with [Fe/H] <
-3.5-$2429, another sample
star, has excesses of N and Sc with respect to Fe. The strong outliers in
abundance ratios among the Fe-peak elements in these C-normal stars, not found
at somewhat higher metallicities, are definitely real. They suggest that at
such low metallicities we are beginning to see the anticipated and long sought
stochastic effects of individual supernova events contributing to the Fe-peak
material within a single star. A detailed comparison of the results of the
analysis procedures adopted by our 0Z project compared to those of the First
Stars VLT Large Project finds a systematic difference for [Fe/H] of ~0.3 dex,
our values always being higher.Comment: Accepted to the Ap
Evolving the theory and praxis of knowledge translation through social interaction: a social phenomenological study
Background: As an inherently human process fraught with subjectivity, dynamic interaction, and change, social interaction knowledge translation (KT) invites implementation scientists to explore what might be learned from adopting the academic tradition of social constructivism and an interpretive research approach. This paper presents phenomenological investigation of the second cycle of a participatory action KT intervention in the home care sector to answer the question: What is the nature of the process of implementing KT through social interaction?
Methods: Social phenomenology was selected to capture how the social processes of the KT intervention were experienced, with the aim of representing these as typical socially-constituted patterns. Participants (n = 203), including service providers, case managers, administrators, and researchers organized into nine geographically-determined multi-disciplinary action groups, purposefully selected and audiotaped three meetings per group to capture their enactment of the KT process at early, middle, and end-of-cycle timeframes. Data, comprised of 36 hours of transcribed audiotapes augmented by researchers\u27 field notes, were analyzed using social phenomenology strategies and authenticated through member checking and peer review.
Results: Four patterns of social interaction representing organization, team, and individual interests were identified: overcoming barriers and optimizing facilitators; integrating \u27science push\u27 and \u27demand pull\u27 approaches within the social interaction process; synthesizing the research evidence with tacit professional craft and experiential knowledge; and integrating knowledge creation, transfer, and uptake throughout everyday work. Achieved through relational transformative leadership constituted simultaneously by both structure and agency, in keeping with social phenomenology analysis approaches, these four patterns are represented holistically in a typical construction, specifically, a participatory action KT (PAKT) model.
Conclusion: Study findings suggest the relevance of principles and foci from the field of process evaluation related to intervention implementation, further illuminating KT as a structuration process facilitated by evolving transformative leadership in an active and integrated context. The model provides guidance for proactively constructing a \u27fit\u27 between content, context, and facilitation in the translation of evidence informing professional craft knowledge
Quantification of Urinary Mevalonic Acid as a Biomarker of HMG-CoA Reductase Activity by a Novel Translational LC-MS/MS Method
Background: Mevalonic acid (MVA), as a product of 3-hydroxy-3-methylglutaryl coenzyme A reductase, represents a potential multipurpose biomarker in health and disease. A translational urinary MVA quantification method was developed, validated and used to demonstrate the diurnal variation of urinary MVA excretion in rats and healthy children. Methods: Urinary MVA was converted to mevalonolactone at pH 2, extracted with ethyl acetate and quantified by reversed-phase liquid chromatography-tandem mass spectrometry. Results: The assay had a dynamic range of 0.0156-10 µg/ml with precision <15% CV, accuracy 85-115% and was transferred between laboratories. Urinary MVA excretion in rats and healthy children displayed a diurnal variation consistent with the known diurnal variation of hepatic 3-hydroxy-3-methylglutaryl coenzyme A reductase activity. Conclusion: Urinary MVA can be quantified accurately over a wide dynamic range by a validated translational and transferable method with biomarker capability
Real-time buffer gas pressure tuning in a micro-machined vapor cell
We demonstrate a controllable depletion of the nitrogen buffer gas pressure
in a micro-machined cesium (Cs) vapor cell from the dynamic heating of an
alkali dispenser pill. When the alkali source is laser activated, the gettering
compounds within the alkali pill dispenser reduce the nitrogen (N) content
from the vapor for fine-tuning of the alkali to buffer gas pressure ratio.
Additionally, we decrease the buffer gas pressure below 100mTorr to
evaluate the presence of other potential broadening mechanisms. Real-time
control of the gas pressure ratio in the vapor cell will have notable benefits
for refining atomic sensor performance and provide a routine to achieve various
target pressures across a wafer bonded with a uniform back-filled buffer gas
pressure.Comment: 5 pages, 4 figure
- …