The study predicted practice location of doctors trained at a socially accountable medical school with education programs in over 90 communities. A cross-sectional study examined practice location 10 ...years after the first class graduated from the Northern Ontario School of Medicine (NOSM), Canada. Exact tests and logistic regression models were used to assess practice location in northern Ontario; northern Canada; or other region; and rural (population <10,000) or urban community. There were 435 doctors with 334 (77%) practising as family doctors (FPs), 62 (14%) as generalist specialists and 39 (9%) as other medical or surgical specialists. Approximately 92% (128/139) of FPs who completed both UG and PG at NOSM practised in northern Ontario in 2019, compared with 63% (43/68) who completed only their PG at NOSM, and 24% (30/127) who completed only their UG at NOSM. Overall, 37% (23/62) of generalist specialists and 23% (9/39) of other specialists practised in northern Ontario. Approximately 28% (93/334) of FPs practised in rural Canada compared with 4% (4/101) of all other specialists. FP northern Ontario practice was predicted by completing UG and PG at NOSM (adjusted odds ratio = 46, 95% confidence interval = 20-103) or completing only PG at NOSM (15, 6.0-38) relative to completing only UG at NOSM, and having a northern Ontario hometown (5.3, 2.3-12). Rural Canada practice was predicted by rural hometown (2.3, 1.3-3.8), completing only a NOSM PG (2.0, 1.0-3.9), and age (1.4, 1.1-1.8). This study uniquely demonstrated the interaction of two mechanisms by which medical schools can increase the proportion of doctors' practices located in economically deprived regions: first, admit medical students who grow up in the region; and second, provide immersive UG and PG medical education in the region. Both mechanisms have enabled the majority of NOSM-trained doctors to practise in the underserved region of northern Ontario.
We report and study the translation of exceptionally high catalytic oxygen electroreduction activities of molybdenum-doped octahedrally shaped PtNi(Mo) nanoparticles from conventional thin-film ...rotating disk electrode screenings (3.43 ± 0.35 A mgPt –1 at 0.9 VRHE) to membrane electrode assembly (MEA)-based single fuel cell tests with sustained Pt mass activities of 0.45 A mgPt –1 at 0.9 Vcell, one of the highest ever reported performances for advanced shaped Pt alloys in real devices. Scanning transmission electron microscopy with energy dispersive X-ray analysis (STEM-EDX) reveals that Mo preferentially occupies the Pt-rich edges and vertices of the element-anisotropic octahedral PtNi particles. Furthermore, by combining in situ wide-angle X-ray spectroscopy, X-ray fluorescence, and STEM-EDX elemental mapping with electrochemical measurements, we finally succeeded to realize high Ni retention in activated PtNiMo nanoparticles even after prolonged potential-cycling stability tests. Stability losses at the anodic potential limits were mainly attributed to the loss of the octahedral particle shape. Extending the anodic potential limits of the tests to the Pt oxidation region induced detectable Ni losses and structural changes. Our study shows on an atomic level how Mo adatoms on the surface impact the Ni surface composition, which, in turn, gives rise to the exceptionally high experimental catalytic ORR reactivity and calls for strategies on how to preserve this particular surface composition to arrive at performance stabilities comparable with state-of-the-art spherical dealloyed Pt core–shell catalysts.
► PtCu core–shell advancement for automotive PEMFCs. ► Stability of copper platinum catalysts. ► Basic data for catalysts composition formulation for fuel cells. ► Degradation fingerprint for ...evaluation of catalysts. ► Startup/shutdown high potentials limit the catalysts stability.
Electrochemically dealloyed PtCu alloy nanoparticles successfully meet the automotive technology target of having four times higher Pt mass activity for the electroreduction of molecular oxygen compared to current state-of-the-art platinum catalysts 1. However, the catalysts must also maintain their activity throughout the aggressive automotive drive-cycles in order to be implemented in fuel cells cars. Here, the durability of dealloyed PtCu catalysts was systematically evaluated under various voltage-cycles using a rotating ring disk electrode. The stability of the non-noble metal alloy component was proven at electrode potentials below 0.6V. The platinum stability was evaluated at potentials up to 1.1V to avoid carbon corrosion and then up to 1.2V to be closer to the more aggressive cycles developed in startup/shutdown events of the fuel cells. The major known failure modes such as non-noble metal dissolution, platinum dissolution, and particle growth/agglomeration were monitored in order to understand closely the PtCu nanoparticles behavior under different potential cycles and to provide a degradation fingerprint.
A hydrogen-like atom consisting of a positive muon and an electron is known as muonium. It is a near-ideal two-body system for a precision test of bound-state theory and fundamental symmetries. The ...MuSEUM collaboration performed a new precision measurement of the muonium ground-state hyperfine structure at J-PARC using a high-intensity pulsed muon beam and a high-rate capable positron counter. The resonance of hyperfine transition was successfully observed at a near-zero magnetic field, and the muonium hyperfine structure interval of νHFS=4.463302(4)GHz was obtained with a relative precision of 0.9 ppm. The result was consistent with the previous ones obtained at Los Alamos National Laboratory and the current theoretical calculation. We present a demonstration of the microwave spectroscopy of muonium for future experiments to achieve the highest precision.
Muonic helium atom hyperfine structure (HFS) measurements are a sensitive tool to test the three-body atomic system and bound-state quantum electrodynamics theory, and determine fundamental constants ...of the negative muon magnetic moment and mass. The world's most intense pulsed negative muon beam at the Muon Science Facility of the Japan Proton Accelerator Research Complex allows improvement of previous measurements and testing further CPT invariance by comparing the magnetic moments and masses of positive and negative muons (second-generation leptons). We report new ground-state HFS measurements of muonic helium-4 atoms at a near-zero magnetic field, performed for the first time using a small admixture of CH_{4} as an electron donor to form neutral muonic helium atoms efficiently. Our analysis gives Δν=4464.980(20) MHz (4.5 ppm), which is more precise than both previous measurements at weak and high fields. The muonium ground-state HFS was also measured under the same conditions to investigate the isotopic effect on the frequency shift due to the gas density dependence in He with CH_{4} admixture and compared with previous studies. Muonium and muonic helium can be regarded as light and heavy hydrogen isotopes with an isotopic mass ratio of 36. No isotopic effect was observed within the current experimental precision.
Present status of J-PARC MUSE Shimomura, K; Koda, A; Pant, A D ...
Journal of physics. Conference series,
03/2023, Letnik:
2462, Številka:
1
Journal Article
Recenzirano
Odprti dostop
Abstract
At J-PARC MUSE, since the
µ
SR2017 conference and up to FY2022, there have been several new developments at the facility, including the completion of a new experimental area S2 at the ...surface muon beamline S-line and the first muon beam extraction to the H1 area in the H-line, mainly to carry out high-statistics fundamental physics experiments. Several new studies are also underway, such as applying negative muon non-destructive elemental analysis to the analysis of samples returned from the asteroid Ryugu in the D2 area of the D-line. This paper reports on the latest status of MUSE.
Abstract
Measurements of the muonic helium atom hyperfine structure (HFS) are a sensitive tool to test the theory of three-body atomic systems and bound-state quantum electrodynamics (QED) and to ...determine fundamental constants of the negative muon magnetic moment and mass. The world’s most intense pulsed negative muon beam at J-PARC MUSE brings an opportunity to improve previous measurements and test further CPT invariance by comparing the magnetic moments and masses of positive and negative muons. Test measurements at D-line are now in progress utilizing MuSEUM apparatus at zero field. The first results already have better accuracy than previous measurements in the 1980s. Also, the investigation of a new experimental approach to improve HFS measurements by repolarizing muonic helium atoms using a spin-exchange optical pumping (SEOP) technique was started. If successful, this would drastically improve the measurement accuracy.
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