50 research outputs found
The kinematics of the large western knot in the halo of the young planetary nebula NGC 6543
A detailed analysis is presented of the dominant ionised knot in the halo of
the planetary nebula NGC 6543. Observations were made at high spectral and
spatial resolution of the [OIII] 5007 line using the Manchester echelle
spectrometer combined with the 2.1-m San Pedro Martir Telescope. A 20-element
multislit was stepped across the field to give almost complete spatial coverage
of the knot and surrounding halo. The spectra reveal, for the first time, gas
flows around the kinematically inert knot. The gas flows are found to have
velocities comparable to the sound speed as gas is photo-evaporated off an
ionised surface. No evidence is found of fast wind interaction with the knot
and we find it likely that the fast wind is still contained in a
pressure-driven bubble in the core of the nebula. This rules out the
possibility of the knot having its origin in instabilities at the interface of
the fast and AGB winds. We suggest that the knot is embedded in the slowly
expanding Red Giant wind and that its surfaces are being continually
photoionised by the central star.Comment: 13 pages, 11 figures (all eps format). To be published in MNRAS,
accepted on 6/7/0
Hybridization in parasites: consequences for adaptive evolution, pathogenesis and public health in a changing world
[No abstract available
Effect of remote ischaemic conditioning on clinical outcomes in patients with acute myocardial infarction (CONDI-2/ERIC-PPCI): a single-blind randomised controlled trial.
BACKGROUND: Remote ischaemic conditioning with transient ischaemia and reperfusion applied to the arm has been shown to reduce myocardial infarct size in patients with ST-elevation myocardial infarction (STEMI) undergoing primary percutaneous coronary intervention (PPCI). We investigated whether remote ischaemic conditioning could reduce the incidence of cardiac death and hospitalisation for heart failure at 12 months. METHODS: We did an international investigator-initiated, prospective, single-blind, randomised controlled trial (CONDI-2/ERIC-PPCI) at 33 centres across the UK, Denmark, Spain, and Serbia. Patients (age >18 years) with suspected STEMI and who were eligible for PPCI were randomly allocated (1:1, stratified by centre with a permuted block method) to receive standard treatment (including a sham simulated remote ischaemic conditioning intervention at UK sites only) or remote ischaemic conditioning treatment (intermittent ischaemia and reperfusion applied to the arm through four cycles of 5-min inflation and 5-min deflation of an automated cuff device) before PPCI. Investigators responsible for data collection and outcome assessment were masked to treatment allocation. The primary combined endpoint was cardiac death or hospitalisation for heart failure at 12 months in the intention-to-treat population. This trial is registered with ClinicalTrials.gov (NCT02342522) and is completed. FINDINGS: Between Nov 6, 2013, and March 31, 2018, 5401 patients were randomly allocated to either the control group (n=2701) or the remote ischaemic conditioning group (n=2700). After exclusion of patients upon hospital arrival or loss to follow-up, 2569 patients in the control group and 2546 in the intervention group were included in the intention-to-treat analysis. At 12 months post-PPCI, the Kaplan-Meier-estimated frequencies of cardiac death or hospitalisation for heart failure (the primary endpoint) were 220 (8·6%) patients in the control group and 239 (9·4%) in the remote ischaemic conditioning group (hazard ratio 1·10 [95% CI 0·91-1·32], p=0·32 for intervention versus control). No important unexpected adverse events or side effects of remote ischaemic conditioning were observed. INTERPRETATION: Remote ischaemic conditioning does not improve clinical outcomes (cardiac death or hospitalisation for heart failure) at 12 months in patients with STEMI undergoing PPCI. FUNDING: British Heart Foundation, University College London Hospitals/University College London Biomedical Research Centre, Danish Innovation Foundation, Novo Nordisk Foundation, TrygFonden
Economics and the philosophy of science
Redman DA. Economics and the philosophy of science. New York: Oxford Univ. Pr.; 1991
La teoría de la ciencia de Karl Popper y la econometría
En este ensayo mostraré que la teoría de la falsación ejerció su principalimpacto en los primeros desarrollos de la macroeconomía, quein fortunadamente su impacto a largo plazo no ha sido productivo y que el seguimiento de este desarrollo ayuda a explicar muchos de los actuales escándalos en la econometría y la macroeconomía. Dado que la literatura ha difundido muchos mitos sobre la teoría de la ciencia de Popper, primero revisaré sus teorías de las ciencias naturales y sociales y explicaré por qué la falsación fracasa en ambas ramas antes de exponer la conexión con la econometría