168 research outputs found
The storm tracks and the energy cycle of the Southern Hemisphere: sensitivity to sea-ice boundary conditions
The storm tracks and the energy cycle of the Southern Hemisphere: sensitivity to sea-ice boundary conditions
Compared efficacy of preservation solutions in liver transplantation: A long-term graft outcome study from the european liver transplant registry
International audienceBetween 2003 and 2012, 42 869 first liver transplantations performed in Europe with the use of either University of Wisconsin solution (UW; N = 24 562), histidine-tryptophan-ketoglutarate(HTK; N = 8696), Celsior solution (CE; N = 7756) or Institute Georges Lopez preservation solution (IGL-1; N = 1855) preserved grafts. Alternative solutions to the UW were increasingly used during the last decade. Overall, 3-year graft survival was higher with UW, IGL-1 and CE (75%, 75% and 73%, respectively), compared to the HTK (69%) (p 12 h or grafts used for patients with cancer (p < 0.0001). For partial grafts, 3-year graft survival was 89% for IGL-1, 67% for UW, 68% for CE and 64% for HTK (p = 0.009). Multivariate analysis identified HTK as an independent factor of graft loss, with recipient HIV (+), donor age ≥65 years, recipient HCV (+), main disease acute hepatic failure, use of a partial liver graft, recipient age ≥60 years, no identical ABO compatibility, recipient hepatitis B surface antigen (-), TIT ≥ 12 h, male recipient and main disease other than cirrhosis. HTK appears to be an independent risk factor of graft loss. Both UW and IGL-1, and CE to a lesser extent, provides similar results for full size grafts. For partial deceased donor liver grafts, IGL-1 tends to offer the best graft outcome
Increased insolation threshold for runaway greenhouse processes on Earth like planets
Because the solar luminosity increases over geological timescales, Earth
climate is expected to warm, increasing water evaporation which, in turn,
enhances the atmospheric greenhouse effect. Above a certain critical
insolation, this destabilizing greenhouse feedback can "runaway" until all the
oceans are evaporated. Through increases in stratospheric humidity, warming may
also cause oceans to escape to space before the runaway greenhouse occurs. The
critical insolation thresholds for these processes, however, remain uncertain
because they have so far been evaluated with unidimensional models that cannot
account for the dynamical and cloud feedback effects that are key stabilizing
features of Earth's climate. Here we use a 3D global climate model to show that
the threshold for the runaway greenhouse is about 375 W/m, significantly
higher than previously thought. Our model is specifically developed to quantify
the climate response of Earth-like planets to increased insolation in hot and
extremely moist atmospheres. In contrast with previous studies, we find that
clouds have a destabilizing feedback on the long term warming. However,
subsident, unsaturated regions created by the Hadley circulation have a
stabilizing effect that is strong enough to defer the runaway greenhouse limit
to higher insolation than inferred from 1D models. Furthermore, because of
wavelength-dependent radiative effects, the stratosphere remains cold and dry
enough to hamper atmospheric water escape, even at large fluxes. This has
strong implications for Venus early water history and extends the size of the
habitable zone around other stars.Comment: Published in Nature. Online publication date: December 12, 2013.
Accepted version before journal editing and with Supplementary Informatio
Global Warming: Forecasts by Scientists versus Scientific Forecasts
In 2007, the Intergovernmental Panel on Climate Change’s Working Group One, a panel of experts established by the World Meteorological Organization and the United Nations Environment Programme, issued its Fourth Assessment Report. The Report included predictions of dramatic increases in average world temperatures over the next 92 years and serious harm resulting from the predicted temperature increases. Using forecasting principles as our guide we asked: Are these forecasts a good basis for developing public policy? Our answer is “no”. To provide forecasts of climate change that are useful for policy-making, one would need to forecast (1) global temperature, (2) the effects of any temperature changes, and (3) the effects of feasible alternative policies. Proper forecasts of all three are necessary for rational policy making. The IPCC WG1 Report was regarded as providing the most credible long-term forecasts of global average temperatures by 31 of the 51 scientists and others involved in forecasting climate change who responded to our survey. We found no references in the 1056-page Report to the primary sources of information on forecasting methods despite the fact these are conveniently available in books, articles, and websites. We audited the forecasting processes described in Chapter 8 of the IPCC’s WG1 Report to assess the extent to which they complied with forecasting principles. We found enough information to make judgments on 89 out of a total of 140 forecasting principles. The forecasting procedures that were described violated 72 principles. Many of the violations were, by themselves, critical. The forecasts in the Report were not the outcome of scientific procedures. In effect, they were the opinions of scientists transformed by mathematics and obscured by complex writing. Research on forecasting has shown that experts’ predictions are not useful in situations involving uncertainly and complexity. We have been unable to identify any scientific forecasts of global warming. Claims that the Earth will get warmer have no more credence than saying that it will get colder
Proceedings of the COME-IN! Thematic Conferences: The inclusive museum ‐ Challenges and Solutions, State of the Art and Perspectives: Activity A.C.3 Publications / Deliverable D.C.3.1 Transnational publications
A new evaluation of the uncertainty associated with CDIAC estimates of fossil fuel carbon dioxide emission
Three uncertainty assessments associated with the global total of carbon dioxide emitted from fossil fuel use and cement production are presented. Each assessment has its own strengths and weaknesses and none give a full uncertainty assessment of the emission estimates. This approach grew out of the lack of independent measurements at the spatial and temporal scales of interest. Issues of dependent and independent data are considered as well as the temporal and spatial relationships of the data. The result is a multifaceted examination of the uncertainty associated with fossil fuel carbon dioxide emission estimates. The three assessments collectively give a range that spans from 1.0 to 13% (2 σ). Greatly simplifying the assessments give a global fossil fuel carbon dioxide uncertainty value of 8.4% (2 σ). In the largest context presented, the determination of fossil fuel emission uncertainty is important for a better understanding of the global carbon cycle and its implications for the physical, economic and political world
Rupture of Hepatocellular Carcinoma into the Biliary System with Resulting Bile Duct Thrombi: Report of Two Cases
We report two cases of hepatocellular carcinoma revealed by jaundice and the presence of free-floating tumoural fragments within the biliary system. Two men (one of 64 and one of 73) presented with isolated jaundice. The results from ultrasound, CT and MRI were suggestive of a cholangiocarcinoma. Surgical intervention demonstrated bile duct thrombi from the primary tumour causing obstructive jaundice
The Reliability of Global and Hemispheric Surface Temperature Records
The purpose of this review article is to discuss the development and associated estimation of uncertainties in the global and hemispheric surface temperature records. The review begins by detailing the groups that produce surface temperature datasets. After discussing the reasons for similarities and differences between the various products, the main issues that must be addressed when deriving accurate estimates, particularly for hemispheric and global averages, are then considered. These issues are discussed in the order of their importance for temperature records at these spatial scales: biases in SST data, particularly before the 1940s; the exposure of land-based thermometers before the development of louvred screens in the late 19th century; and urbanization effects in some regions in recent decades. The homogeneity of land-based records is also discussed; however, at these large scales it is relatively unimportant. The article concludes by illustrating hemispheric and global temperature records from the four groups that produce series in near-real time
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