North Atlantic climate far more predictable than models imply.

Quantifying signals and uncertainties in climate models is essential for the detection, attribution, prediction and projection of climate change1-3. Although inter-model agreement is high for large-scale temperature signals, dynamical changes in atmospheric circulation are very uncertain4. This leads to low confidence in regional projections, especially for precipitation, over the coming decades5,6. The chaotic nature of the climate system7-9 may also mean that signal uncertainties are largely irreducible. However, climate projections are difficult to verify until further observations become available. Here we assess retrospective climate model predictions of the past six decades and show that decadal variations in North Atlantic winter climate are highly predictable, despite a lack of agreement between individual model simulations and the poor predictive ability of raw model outputs. Crucially, current models underestimate the predictable signal (the predictable fraction of the total variability) of the North Atlantic Oscillation (the leading mode of variability in North Atlantic atmospheric circulation) by an order of magnitude. Consequently, compared to perfect models, 100 times as many ensemble members are needed in current models to extract this signal, and its effects on the climate are underestimated relative to other factors. To address these limitations, we implement a two-stage post-processing technique. We first adjust the variance of the ensemble-mean North Atlantic Oscillation forecast to match the observed variance of the predictable signal. We then select and use only the ensemble members with a North Atlantic Oscillation sufficiently close to the variance-adjusted ensemble-mean forecast North Atlantic Oscillation. This approach greatly improves decadal predictions of winter climate for Europe and eastern North America. Predictions of Atlantic multidecadal variability are also improved, suggesting that the North Atlantic Oscillation is not driven solely by Atlantic multidecadal variability. Our results highlight the need to understand why the signal-to-noise ratio is too small in current climate models10, and the extent to which correcting this model error would reduce uncertainties in regional climate change projections on timescales beyond a decade.

[Are surgical renal biopsies useful for clinical prognosis in renal artery stenosis?]. / Les biopsies rénales chirurgicales dans la sténose de l'artère rénale sont-elles utiles au pronostic clinique?

The most significant results show the predominance of arteriolar lesions in the controlateral kidney, The most significant results show the predotients with unilateral renal artery stenosis. and parenchymal lesions of the kidney with stenosis in patients with atherosclerosis. These results do not seem to provide information which would alter the clinical management in any particular case.

Increased level of factor VIII complex in severe arterial hypertension.

Factor VIII complex was studied in patients presenting arterial hypertension. Visceral involvement was quantified using a clinical index calculated from ocular fundus, renal function and left ventricular hypertrophy data. A significant correlation was found between the mean arterial pressure, the visceral involvement and the level of complex VIII. Nevertheless, other data obtained in different patients (Conn's disease) suggest that the visceral involvement (and not the mean arterial pressure) is the main determining factor in the increase of factor VIII complex.