195,075 research outputs found
Responding to the risk of reducing resources: development of a framework for future change programmes in English environmental health services
Environmental Health Services in the UK have been subject to significant resource reduction from 2010 to 2018. It is suggested that services risk becoming unsustainable unless efficient and effective ways of working are employed. This research explored the experience of practitioners who are developing and delivering evolving Environmental Health Services in English local authorities in the context of deep cutting budget reductions. A range of ‘non-traditional’ service delivery models has been examined including outsourcing, shared services, regional delivery models and mutualisation arrangements. The models were at various stages of development from planning through to full transformation. Interviews were carried out with the participants involved in the change process to capture their experience of change and the impact on service delivery. Fieldwork was undertaken between 2014 and 2016. Thematic analysis of interview transcripts identified six central themes of the experience of change: ‘Managing changes effectively’; ‘Understanding the reasons for change’; ‘Understanding the nature of Environmental Health’; ‘Meaningful consultation’; ‘Viability of the proposal’; And ‘Planning and timeliness’. Further analysis of the data developed seven overarching themes: ‘Ethos of public services’, ‘Getting it right’, ‘Emerging service demands’, ‘Resilience’, ‘Trust’, ‘Skills development’ and ‘Risk’. A framework for future change programmes in Environmental Health Services has been developed which takes into account the lessons learnt by organisations that have previously undergone significant change in their response to the risk of a reducing resource. Environmental Health Services undergoing transformation will benefit from using this framework to examine their own organisation when they are establishing the need for change, making decisions, planning and transition. Use of this framework can mitigate against risks of unsustainable or undeliverable Environmental Health Services
The subtropical global plume in the Pacific Exploratory Mission-Tropics A (PEM-Tropics A), PEM-Tropics B, and the Global Atmospheric Sampling Program (GASP): How tropical emissions affect the remote Pacific
[1] An extended southern subtropical plume of CO meanders>15,000 km around the world, gradually spreading around 20 S. This southern pollution plume is most noticeable in the burning season, southern spring; a similar subtropical plume appears in the northern spring. We use tracer maps to guide the use of trajectories to trace observations of the plume to their origins. The MM5 mesoscale model provides high-resolution, near-global synoptic reconstructions of the weather. Two situations are analyzed: NASA’s airborne Pacific Exploratory Mission-Tropics A (PEM-Tropics A) period, September–October 1996 and the PEM-Tropics B period, March–April 1999. Similar features are noted for a much earlier mission in 1977, which apparently captured the first, but never-recognized, samples of the global pollution of the Southern Hemisphere. For PEM-Tropics A, near-source pieces of the plume are clearly seen in the Total Ozone Mapping Spectrometer (TOMS) absorbing aerosol product and are well simulated. Downwind, the aircraft sampling of several strands deriving from a single plume seems representative and well simulated. A general mechanism of the plume emerges: The southern plume arises in surface accumulation regions in Africa and Sout
Autocatalytic plume pinch-off
A localized source of buoyancy flux in a non-reactive fluid medium creates a
plume. The flux can be provided by either heat, a compositional difference
between the fluid comprising the plume and its surroundings, or a combination
of both. For autocatalytic plumes produced by the iodate-arsenous acid
reaction, however, buoyancy is produced along the entire reacting interface
between the plume and its surroundings. Buoyancy production at the moving
interface drives fluid motion, which in turn generates flow that advects the
reaction front. As a consequence of this interplay between fluid flow and
chemical reaction, autocatalytic plumes exhibit a rich dynamics during their
ascent through the reactant medium. One of the more interesting dynamical
features is the production of an accelerating vortical plume head that in
certain cases pinches-off and detaches from the upwelling conduit. After
pinch-off, a new plume head forms in the conduit below, and this can lead to
multiple generations of plume heads for a single plume initiation. We
investigated the pinch-off process using both experimentation and simulation.
Experiments were performed using various concentrations of glycerol, in which
it was found that repeated pinch-off occurs exclusively in a specific
concentration range. Autocatalytic plume simulations revealed that pinch-off is
triggered by the appearance of accelerating flow in the plume conduit.Comment: 10 figures. Accepted for publication in Phys Rev E. See also
http://www.physics.utoronto.ca/nonlinear/papers_chemwave.htm
Control of plume interference effects on axisymmetric afterbodies
Plume interference effects on the axisymmetric flowfields around powered missiles are investigated using computational techniques. The study is mainly to understand the physics of the plume-induced shock and separation particularly at high plume to exit pressure ratios with and without shock-turbulent boundary layer control methods
The effect of relative plasma plume delay on the properties of complex oxide films grown by multi-laser multi-target combinatorial pulsed laser deposition
We report the effects of relative time delay of plasma plumes on thin garnet crystal films fabricated by dual-beam, combinatorial pulsed laser deposition. Relative plume delay was found to affect both the lattice constant and elemental composition of mixed Gd3Ga5O12 (GGG) and Gd3Sc2Ga5O12 (GSGG) films. Further analysis of the plasmas was undertaken using a Langmuir probe, which revealed that for relative plume delays shorter than ~200 µs, the second plume travels through a partial vacuum created by the first plume, leading to higher energy ion bombardment of the growing film. The resulting in-plane stresses are consistent with the transition to a higher value of lattice constant normal to the film plane that was observed around this delay value. At delays shorter than ~10 µs, plume propagation was found to overlap, leading to scattering of lighter ions from the plume and a change in stoichiometry of the resultant films
Summary of nozzle-exhaust plume flowfield analyses related to space shuttle applications
Exhaust plume shape simulation is studied, with the major effort directed toward computer program development and analytical support of various plume related problems associated with the space shuttle. Program development centered on (1) two-phase nozzle-exhaust plume flows, (2) plume impingement, and (3) support of exhaust plume simulation studies. Several studies were also conducted to provide full-scale data for defining exhaust plume simulation criteria. Model nozzles used in launch vehicle test were analyzed and compared to experimental calibration data
The structure of molecular clumps around high-mass young stellar objects
We have used the IRAM 30-m and FCRAO 14-m telescopes to observe the molecular
clumps associated with 12 ultracompact (UC) HII regions in the J=6-5, 8-7 and
13-12 rotational transitions of methyl-acetylene (CH3C2H). Under the assumption
of LTE and optically thin emission, we have derived temperature estimates
ranging from 30 to 56 K. We estimate that the clumps have diameters of 0.2-1.6
pc, H_2 densities of 10^5-10^6 {cm^{-3}}, and masses of 10^2-2 10^4 M_\odot. We
compare these values with those obtained by other authors from different
molecular tracers and find that the H_2 density and the temperature inside the
clumps vary respectively like n_{H_2} ~ R^{-2.6} and T ~ R^{-0.5}, with R
distance from the centre. We also find that the virial masses of the clumps are
~3 times less than those derived from the CH3C2H column densities: we show that
a plausible explanation is that magnetic fields play an important role to
stabilise the clumps, which are on the verge of gravitational collapse.
Finally, we show that the CH3C2H line width increases for decreasing distance
from the clump centre: this effect is consistent with infall in the inner
regions of the clumps. We conclude that the clumps around UC HII regions are
likely to be transient (~10^(5) yr) entities, remnants of isothermal spheres
currently undergoing gravitational collapse: the high mass accretion rates
(~10^{-2} M_\odot yr^{-1}) lead to massive star formation at the centre of such
clumps.Comment: 15 pages, 11 figures, A & A in pres
Hierarchical Fragmentation and Jet-like Outflows in IRDC G28.34+0.06, a Growing Massive Protostar Cluster
We present Submillimeter Array (SMA) \lambda = 0.88mm observations of an
infrared dark cloud (IRDC) G28.34+0.06. Located in the quiescent southern part
of the G28.34 cloud, the region of interest is a massive (\,\msun)
molecular clump P1 with a luminosity of \lsun, where our previous
SMA observations at 1.3mm have revealed a string of five dust cores of 22-64
\msun\ along the 1 pc IR-dark filament. The cores are well aligned at a
position angle of 48 degrees and regularly spaced at an average projected
separation of 0.16 pc. The new high-resolution, high-sensitivity 0.88\,mm image
further resolves the five cores into ten compact condensations of 1.4-10.6
\msun, with sizes a few thousands AU. The spatial structure at clump (
pc) and core ( pc) scales indicates a hierarchical fragmentation.
While the clump fragmentation is consistent with a cylindrical collapse, the
observed fragment masses are much larger than the expected thermal Jeans
masses. All the cores are driving CO(3-2) outflows up to 38 km/s, majority of
which are bipolar, jet-like outflows. The moderate luminosity of the P1 clump
sets a limit on the mass of protostars of 3-7 \msun. Because of the large
reservoir of dense molecular gas in the immediate medium and ongoing accretion
as evident by the jet-like outflows, we speculate that P1 will grow and
eventually form a massive star cluster. This study provides a first glimpse of
massive, clustered star formation that currently undergoes through an
intermediate-mass stage.Comment: 24 pages, 4 figures, 4 tables, accepted to Ap
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