521 research outputs found
Analysis of the 2007/8 Defra Farm Business Survey Energy Module
Key points This study has delivered an invaluable baseline estimate of energy
use and greenhouse gas (GHG) emissions on commercial farms in England. Energy
use and GHG emissions associated with particular commodities were quantified and
results broadly agreed with those derived by Life Cycle Assessment, but with
much scatter in the environmental performance of farms.Direct energy use on
farms was generally less that indirect (embedded) energy use, except for
horticulture, which is dominated by heating fuel use. In contrast, most GHG
emissions are incurred on farms, rather than as embedded emissions.Scatter in
both environmental and economic performance underlies the somewhat disappointing
finding of no clear positive link between farm financial performance and energy
use or GHG emissions. However, the mere existence of these ranges shows that
there is scope for improvement in both financial and environmental performance
and that there is no apparent barrier for both to be achievable in harmony. The
recording of such farm-level energy data is essential for the future, as it
should enable improvements to be made in efficiency of energy use. The improved
UK agricultural GHG inventory will depend on high quality energy data on
agricultural activities. This study will be invaluable in identifying the level
of detail needed. Future data requirements include: contractor work rates and
fuel use per unit area and per unit time, fertiliser and pesticide use by brand
name, enhanced output data, especially animal live weights, and horticultural
produce recorded by weight rather than by value
Measurement of the electron's electric dipole moment using YbF molecules: methods and data analysis
We recently reported a new measurement of the electron's electric dipole
moment using YbF molecules [Nature 473, 493 (2011)]. Here, we give a more
detailed description of the methods used to make this measurement, along with a
fuller analysis of the data. We show how our methods isolate the electric
dipole moment from imperfections in the experiment that might mimic it. We
describe the systematic errors that we discovered, and the small corrections
that we made to account for these. By making a set of additional measurements
with greatly exaggerated experimental imperfections, we find upper bounds on
possible uncorrected systematic errors which we use to determine the systematic
uncertainty in the measurement. We also calculate the size of some systematic
effects that have been important in previous electric dipole moment
measurements, such as the motional magnetic field effect and the geometric
phase, and show them to be negligibly small in the present experiment. Our
result is consistent with an electric dipole moment of zero, so we provide
upper bounds to its size at various confidence levels. Finally, we review the
prospects for future improvements in the precision of the experiment.Comment: 35 pages, 15 figure
“Making a difference” – Medical students’ opportunities for transformational change in health care and learning through quality improvement projects
Background Quality improvement is increasingly becoming an essential aspect of the medical curriculum, with the intention of improving the health care system to provide better health care. The aim of this study was to explore undergraduate medical students’ experiences of their involvement in quality improvement projects during a district health rotation. Methods Student group reports from rotations in learning centres of the University of Pretoria in Mpumalanga Province, South Africa were analysed for the period 2012 to 2015. Interviews were conducted with health care providers at four learning centres in 2013. Results Three main themes were identified: (1) ‘Situated learning’, describing students’ exposure to the discrepancies between ideal and reality in a real-life situation and how they learned to deal with complex situations, individually and as student group; (2) ‘Facing dilemmas’, describing how students were challenged about the non-ideal reality; (3) ‘Making a difference’, describing the impact of the students’ projects, with greater understanding of themselves and others through working in teams but also making a change in the health care system. Conclusion Quality improvement projects can provide an opportunity for both the transformation of health care and for transformative learning, with individual and ‘collective’ self-authorship
Atomic Parity Violation and Precision Electroweak Physics - An Updated Analysis
A new analysis of parity violation in atomic cesium has led to the improved
value of the weak charge, . The implications
of this result for constraining the Peskin-Takeuchi parameters S and T and for
guiding searches for new Z bosons are discussed.Comment: 8 pages, LaTeX, 3 figures, Submitted to Physical Review D. Updated
experimental inputs and references; clarification of notatio
The nuclear Schiff moment and time invariance violation in atoms
Parity and time invariance violating (P,T-odd) nuclear forces produce P,T-odd
nuclear moments. In turn, these moments can induce electric dipole moments
(EDMs) in atoms through the mixing of electron wavefunctions of opposite
parity. The nuclear EDM is screened by atomic electrons. The EDM of an atom
with closed electron subshells is induced by the nuclear Schiff moment.
Previously the interaction with the Schiff moment has been defined for a
point-like nucleus. No problems arise with the calculation of the electron
matrix element of this interaction as long as the electrons are considered to
be non-relativistic. However, a more realistic model obviously involves a
nucleus of finite-size and relativistic electrons. In this work we have
calculated the finite nuclear-size and relativistic corrections to the Schiff
moment. The relativistic corrections originate from the electron wavefunctions
and are incorporated into a ``nuclear'' moment, which we term the local dipole
moment. For mercury these corrections amount to about 25%. We have found that
the natural generalization of the electrostatic potential of the Schiff moment
for a finite-size nucleus corresponds to an electric field distribution which,
inside the nucleus, is well approximated as constant and directed along the
nuclear spin, and outside the nucleus is zero. Also in this work the plutonium
atomic EDM is estimated.Comment: 16 pages, 1 figure, minor misprints correcte
Search for electric dipole moments at storage rings
Permanent electric dipole moments (EDMs) violate parity and time reversal
symmetry. Within the Standard Model (SM) they are many orders of magnitude
below present experimental sensitivity. Many extensions of the SM predict much
larger EDMs, which are therefore an excellent probe for the existence of "new
physics". Until recently it was believed that only electrically neutral systems
could be used for sensitive searches of EDMs. With the introduction of a novel
experimental method, high precision for charged systems will be within reach as
well. The features of this method and its possibilities are discussed.Comment: Proc. EXA2011, 6 pages;
http://www.springerlink.com/content/45l35376832vhrg0
The development and evaluation of mini-GEMs: a short, focused, online e-learning videos in geriatric medicine
Mini Geriatric E-Learning Modules (Mini-GEMs) are short, focused, e-learning videos on geriatric medicine topics, hosted on YouTube, which are targeted at junior doctors working with older people. This study aimed to explore how these resources are accessed and used. The authors analyzed the viewing data from 22 videos published over the first 18 months of the Mini-GEM project. We conducted a focus group of U.K. junior doctors considering their experiences with Mini-GEMS. The Mini-GEMs were viewed 10,291 times over 18 months, equating to 38,435 minutes of total viewing time. The average viewing time for each video was 3.85 minutes. Learners valued the brevity and focused nature of the Mini-GEMs and reported that they watched them in a variety of settings to supplement clinical experiences and consolidate learning. Watching the videos led to an increase in self-reported confidence in managing older patients. Mini-GEMs can effectively disseminate clinical teaching material to a wide audience. The videos are valued by junior doctors due to their accessibility and ease of use
Role of Present and Future Atomic Parity Violation Experiments in Precision Electroweak Tests
Recent reanalyses of the atomic physics effects on the weak charge in cesium
have led to a value in much closer agreement with predictions of the Standard
Model. We review precision electroweak tests, their implications for upper
bounds on the mass of the Higgs boson, possible ways in which these bounds may
be circumvented, and the requirements placed upon accuracy of future atomic
parity violation experiments by these considerations.Comment: 10 pages, LaTeX, 1 figure, to be submitted to Physical Review D, new
data on neutrino deep inelastic scattering include
Symmetry-breaking in chiral polymerisation
We propose a model for chiral polymerisation and investigate its symmetric
and asymmetric solutions. The model has a source species which decays into
left- and right-handed types of monomer, each of which can polymerise to form
homochiral chains; these chains are susceptible to `poisoning' by the opposite
handed monomer. Homochiral polymers are assumed to influence the proportion of
each type of monomer formed from the precursor. We show that for certain
parameter values a positive feedback mechanism makes the symmetric steady-state
solution unstable. The kinetics of polymer formation are then analysed in the
case where the system starts from zero concentrations of monomer and chains. We
show that following a long induction time, extremely large concentrations of
polymers are formed for a short time, during this time an asymmetry introduced
into the system by a random external perturbation may be massively amplified.
The system then approaches one of the steady-state solutions described above.Comment: 26pages, 6 Figure
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