51 research outputs found
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The northern hemisphere circumglobal teleconnection in a seasonal forecast model and its relationship to European summer forecast skill
Forecasting seasonal variations in European summer weather represents a considerable challenge. Here, we assess the performance of a seasonal forecasting model at representing a major mode of northern hemisphere summer climate variability, the circumglobal teleconnection (CGT), and the implications of errors in its representation on seasonal forecasts for the European summer (June, July, August). Using seasonal hindcasts initialised at the start of May, we find that the model skill for forecasting the interannual variability of 500 hPa geopotential height is poor, particularly over Europe and several other “centres of action” of the CGT. The model also has a weaker CGT pattern than is observed, particularly in August, when the observed CGT wavetrain is strongest. We investigate several potential causes of this poor skill. First, model variance in geopotential height in west-central Asia (an important region for the maintenance of the CGT) is lower than observed in July and August, associated with a poor representation of the link between this region and Indian monsoon precipitation. Second, analysis of the Rossby wave source shows that the source associated with monsoon heating is both too strong and displaced to the northeast in the model. This is related to errors in monsoon precipitation over the Bay of Bengal and Arabian Sea, where the model has more precipitation than is observed. Third, the model jet is systematically shifted northwards by several degrees latitude over large parts of the northern hemisphere, which may affect the propagation characteristics of Rossby waves in the model
A recipe for simulating the interannual variability of the Asian summer monsoon and its relation with ENSO
Author Posting. © The Authors, 2006. This is the author's version of the work. It is posted here by permission of Springer for personal use, not for redistribution. The definitive version was published in Climate Dynamics 28 (2007): 441-460, doi: 10.1007/s00382-006-0190-0.This study investigates how accurately the interannual variability over the Indian
Ocean basin and the relationship between the Indian summer monsoon and the
El Nino Southern Oscillation (ENSO) can be simulated by different modelling
strategies. With a hierarchy of models, from an atmospherical general circulation
model (AGCM) forced by observed SST, to a coupled model with the ocean
component limited to the tropical Pacific and Indian Oceans, the role of heat
fluxes and of interactive coupling is analyzed. Whenever sea surface temperature
anomalies in the Indian basin are created by the coupled model, the inverse relationship
between the ENSO index and the Indian summer monsoon rainfall is
recovered, and it is preserved if the atmospherical model is forced by the SSTs
created by the coupled model. If the ocean model domain is limited to the Indian
Ocean, changes in the Walker circulation over the Pacific during El Nino years
induce a decrease of rainfall over the Indian subcontinent. However the observed
correlation between the ENSO and the Indian Ocean Zonal Mode (IOZM) is
not properly modelled and the two indices are not significantly correlated, independently
on season. Whenever the ocean domain extends to the Pacific, and
ENSO can impact both the atmospheric circulation and the ocean subsurface in
the equatorial Eastern Indian Ocean, modelled precipitation patterns associated
both to ENSO and to the IOZM closely resemble the observations.The experiments described were performed as a contribution to the ENSEMBLES
project funded by the European Commission’s 6th Framework Programme, contract
number GOCE-CT-2003-505539
Global patient outcomes after elective surgery: prospective cohort study in 27 low-, middle- and high-income countries.
BACKGROUND: As global initiatives increase patient access to surgical treatments, there remains a need to understand the adverse effects of surgery and define appropriate levels of perioperative care. METHODS: We designed a prospective international 7-day cohort study of outcomes following elective adult inpatient surgery in 27 countries. The primary outcome was in-hospital complications. Secondary outcomes were death following a complication (failure to rescue) and death in hospital. Process measures were admission to critical care immediately after surgery or to treat a complication and duration of hospital stay. A single definition of critical care was used for all countries. RESULTS: A total of 474 hospitals in 19 high-, 7 middle- and 1 low-income country were included in the primary analysis. Data included 44 814 patients with a median hospital stay of 4 (range 2-7) days. A total of 7508 patients (16.8%) developed one or more postoperative complication and 207 died (0.5%). The overall mortality among patients who developed complications was 2.8%. Mortality following complications ranged from 2.4% for pulmonary embolism to 43.9% for cardiac arrest. A total of 4360 (9.7%) patients were admitted to a critical care unit as routine immediately after surgery, of whom 2198 (50.4%) developed a complication, with 105 (2.4%) deaths. A total of 1233 patients (16.4%) were admitted to a critical care unit to treat complications, with 119 (9.7%) deaths. Despite lower baseline risk, outcomes were similar in low- and middle-income compared with high-income countries. CONCLUSIONS: Poor patient outcomes are common after inpatient surgery. Global initiatives to increase access to surgical treatments should also address the need for safe perioperative care. STUDY REGISTRATION: ISRCTN5181700
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Anti-HIV effects of chloroquine: inhibition of viral particle glycosylation and synergism with protease inhibitors
We tested the effects of chloroquine (CQ) on glycosylation of HIV particles and in combination with protease inhibitors (PIs) on HIV replication and on P-glycoprotein (P-gp)/multidrug resistance protein-1 (MRP1)
Pro-Science Rhetoric or a Research Program? : Naturalism(s) in the Cognitive-Evolutionary Study of Religion
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Composição da entomofauna da Floresta Nacional do Araripe em diferentes vegetações e estações do ano
Preservation Methods Alter Carbon and Nitrogen Stable Isotope Values in Crickets (Orthoptera: Grylloidea)
<div><p>Stable isotope analysis (SIA) is an important tool for investigation of animal dietary habits for determination of feeding niche. Ideally, fresh samples should be used for isotopic analysis, but logistics frequently demands preservation of organisms for analysis at a later time. The goal of this study was to establish the best methodology for preserving forest litter-dwelling crickets for later SIA analysis without altering results. We collected two cricket species, <i>Phoremia</i> sp. and <i>Mellopsis doucasae</i>, from which we prepared 70 samples per species, divided among seven treatments: (i) freshly processed (control); preserved in fuel ethanol for (ii) 15 and (iii) 60 days; preserved in commercial ethanol for (iv) 15 and (v) 60 days; fresh material frozen for (vi) 15 and (vii) 60 days. After oven drying, samples were analyzed for <i>δ</i><sup>15</sup>N, <i>δ</i><sup>13</sup>C values, N(%), C(%) and C/N atomic values using continuous flow isotope ratio mass spectrometry. All preservation methods tested, significantly impacted <i>δ</i><sup>13</sup>C and <i>δ</i><sup>15</sup>N and C/N atomic values. Chemical preservatives caused <i>δ</i><sup>13</sup>C enrichment as great as 1.5‰, and <i>δ</i><sup>15</sup>N enrichment as great as 0.9‰; the one exception was <i>M. doucasae</i> stored in ethanol for 15 days, which had <i>δ</i><sup>15</sup>N depletion up to 1.8‰. Freezing depleted <i>δ</i><sup>13</sup>C and <i>δ</i><sup>15</sup>N by up to 0.7 and 2.2‰, respectively. C/N atomic values decreased when stored in ethanol, and increased when frozen for 60 days for both cricket species. Our results indicate that all preservation methods tested in this study altered at least one of the tested isotope values when compared to fresh material (controls). We conclude that only freshly processed material provides adequate SIA results for litter-dwelling crickets.</p></div
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