374 research outputs found
Impurity effects on the melting of Ni clusters
We demonstrate that the addition of a single carbon impurity leads to
significant changes in the thermodynamic properties of Ni clusters consisting
of more than a hundred atoms. The magnitude of the change induced is dependent
upon the parameters of the Ni-C interaction. Hence, thermodynamic properties of
Ni clusters can be effectively tuned by the addition of an impurity of a
particular type. We also show that the presence of a carbon impurity
considerably changes the mobility and diffusion of atoms in the Ni cluster at
temperatures close to its melting point. The calculated diffusion coefficients
of the carbon impurity in the Ni cluster can be used for a reliable estimate of
the growth rate of carbon nanotubes.Comment: 27 pages, 13 figure
Rigorous treatment of electrostatics for spatially varying dielectrics based on energy minimization
A novel energy minimization formulation of electrostatics that allows
computation of the electrostatic energy and forces to any desired accuracy in a
system with arbitrary dielectric properties is presented. An integral equation
for the scalar charge density is derived from an energy functional of the
polarization vector field. This energy functional represents the true energy of
the system even in non-equilibrium states. Arbitrary accuracy is achieved by
solving the integral equation for the charge density via a series expansion in
terms of the equation's kernel, which depends only on the geometry of the
dielectrics. The streamlined formalism operates with volume charge
distributions only, not resorting to introducing surface charges by hand.
Therefore, it can be applied to any spatial variation of the dielectric
susceptibility, which is of particular importance in applications to
biomolecular systems. The simplicity of application of the formalism to real
problems is shown with analytical and numerical examples.Comment: 27 pages, 5 figure
The Waveform Digitiser of the Double Chooz Experiment: Performance and Quantisation Effects on PhotoMultiplier Tube Signals
We present the waveform digitiser used in the Double Chooz experiment. We
describe the hardware and the custom-built firmware specifically developed for
the experiment. The performance of the device is tested with regards to
digitising low light level signals from photomultiplier tubes and measuring
pulse charge. This highlights the role of quantisation effects and leads to
some general recommendations on the design and use of waveform digitisers.Comment: 14 pages, 8 figures, accepted for publication in JINS
Global health competencies in UK postgraduate medical training: a scoping review and curricular content analysis
ObjectiveTo assess global health (GH) training in all postgraduate medical education in the UK.DesignMixed methodology: scoping review and curricular content analysis using two GH competency frameworks.Setting and participantsA scoping review (until December 2017) was used to develop a framework of GH competencies for doctors. National postgraduate medical training curricula were analysed against this and a prior framework for GH competencies. The number of core competencies addressed and/or appearing in each programme was recorded.OutcomesThe scoping review identified eight relevant publications. A 16-competency framework was developed and, with a prior 5-competency framework, used to analyse each of 71 postgraduate medical curricula. Curricula were examined by a team of researchers and relevant learning outcomes were coded as one of the 5 or 16 core competencies. The number of core competencies in each programme was recorded.ResultsUsing the 5-competency and 16-competency frameworks, 23 and 20, respectively, out of 71 programmes contained no global health competencies, most notably the Foundation Programme (equivalent to internship), a compulsory programme for UK medical graduates. Of a possible 16 competencies, the mean number across all 71 programmes was 1.73 (95% CI 1.42 to 2.04) and the highest number were in paediatrics and infectious diseases, each with five competencies. Of the 16 core competencies, global burden of disease and socioeconomic determinants of health were the two most cited with 47 and 35 citations, respectively. 8/16 competencies were not cited in any curriculum.ConclusionsEquity of care and the challenges of practising in an increasingly globalised world necessitate GH competencies for all doctors. Across the whole of postgraduate training, the majority of UK doctors are receiving minimal or no training in GH. Our GH competency framework can be used to map and plan integration across postgraduate programmes.</jats:sec
Time to go global: a consultation on global health competencies for postgraduate doctors
BACKGROUND: Globalisation is having profound impacts on health and healthcare. We solicited the views of a wide range of stakeholders in order to develop core global health competencies for postgraduate doctors. METHODS: Published literature and existing curricula informed writing of seven global health competencies for consultation. A modified policy Delphi involved an online survey and face-to-face and telephone interviews over three rounds. RESULTS: Over 250 stakeholders participated, including doctors, other health professionals, policymakers and members of the public from all continents of the world. Participants indicated that global health competence is essential for postgraduate doctors and other health professionals. Concerns were expressed about overburdening curricula and identifying what is 'essential' for whom. Conflicting perspectives emerged about the importance and relevance of different global health topics. Five core competencies were developed: (1) diversity, human rights and ethics; (2) environmental, social and economic determinants of health; (3) global epidemiology; (4) global health governance; and (5) health systems and health professionals. CONCLUSIONS: Global health can bring important perspectives to postgraduate curricula, enhancing the ability of doctors to provide quality care. These global health competencies require tailoring to meet different trainees' needs and facilitate their incorporation into curricula. Healthcare and global health are ever-changing; therefore, the competencies will need to be regularly reviewed and updated
Search for neutrino oscillations on a long base-line at the CHOOZ nuclear power station
This final article about the CHOOZ experiment presents a complete description
of the electron antineutrino source and detector, the calibration methods and
stability checks, the event reconstruction procedures and the Monte Carlo
simulation. The data analysis, systematic effects and the methods used to reach
our conclusions are fully discussed. Some new remarks are presented on the
deduction of the confidence limits and on the correct treatment of systematic
errors.Comment: 41 pages, 59 figures, Latex file, accepted for publication by
Eur.Phys.J.
Initial Results from the CHOOZ Long Baseline Reactor Neutrino Oscillation Experiment
Initial results are presented from CHOOZ, a long-baseline reactor-neutrino
vacuum-oscillation experiment. Electron antineutrinos were detected by a liquid
scintillation calorimeter located at a distance of about 1 km. The detector was
constructed in a tunnel protected from cosmic rays by a 300 MWE rock
overburden. This massive shielding strongly reduced potentially troublesome
backgrounds due to cosmic-ray muons, leading to a background rate of about one
event per day, more than an order of magnitude smaller than the observed
neutrino signal. From the statistical agreement between detected and expected
neutrino event rates, we find (at 90% confidence level) no evidence for
neutrino oscillations in the electron antineutrino disappearance mode for the
parameter region given approximately by deltam**2 > 0.9 10**(-3) eV**2 for
maximum mixing and (sin(2 theta)**2) > 0.18 for large deltam**2.Comment: 13 pages, Latex, submitted to Physics Letters
Limits on Neutrino Oscillations from the CHOOZ Experiment
We present new results based on the entire CHOOZ data sample. We find (at 90%
confidence level) no evidence for neutrino oscillations in the anti_nue
disappearance mode, for the parameter region given by approximately Delta m**2
> 7 x 10**-4 eV^2 for maximum mixing, and sin**2(2 theta) = 0.10 for large
Delta m**2. Lower sensitivity results, based only on the comparison of the
positron spectra from the two different-distance nuclear reactors, are also
presented; these are independent of the absolute normalization of the anti_nue
flux, the cross section, the number of target protons and the detector
efficiencies.Comment: 19 pages, 11 figures, Latex fil
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New experimental limits on the Pauli forbidden transitions in C nuclei obtained with 485 days Borexino data
The Pauli exclusion principle (PEP) has been tested for nucleons () in
with the Borexino detector.The approach consists of a search for
, , and emitted in a non-Paulian transition of
1- shell nucleons to the filled 1 shell in nuclei. Due to the
extremely low background and the large mass (278 t) of the Borexino detector,
the following most stringent up-to-date experimental bounds on PEP violating
transitions of nucleons have been established:
y, y,
y,
y and y, all at 90% C.L. The corresponding upper
limits on the relative strengths for the searched non-Paulian electromagnetic,
strong and weak transitions have been estimated: , and .Comment: 9 pages, 6 figure
Recent Borexino results and prospects for the near future
The Borexino experiment, located in the Gran Sasso National Laboratory, is an
organic liquid scintillator detector conceived for the real time spectroscopy
of low energy solar neutrinos. The data taking campaign phase I (2007 - 2010)
has allowed the first independent measurements of 7Be, 8B and pep fluxes as
well as the first measurement of anti-neutrinos from the earth. After a
purification of the scintillator, Borexino is now in phase II since 2011. We
review here the recent results achieved during 2013, concerning the seasonal
modulation in the 7Be signal, the study of cosmogenic backgrounds and the
updated measurement of geo-neutrinos. We also review the upcoming measurements
from phase II data (pp, pep, CNO) and the project SOX devoted to the study of
sterile neutrinos via the use of a 51Cr neutrino source and a 144Ce-144Pr
antineutrino source placed in close proximity of the active material.Comment: 8 pages, 11 figures. To be published as proceedings of Rencontres de
Moriond EW 201
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