Solar wind dynamic pressure effect on planetary wave propagation and synoptic-scale Rossby wave breaking

We provide statistical evidence of the effect of the solar wind dynamic pressure (Psw) on the northern winter and spring circulations. We find that the vertical structure of the Northern Annular Mode (NAM), the zonal mean circulation, and Eliassen-Palm (EP)-flux anomalies show a dynamically consistent pattern of downward propagation over a period of ~45 days in response to positive Psw anomalies. When the solar irradiance is high, the signature of Psw is marked by a positive NAM anomaly descending from the stratosphere to the surface during winter. When the solar irradiance is low, the Psw signal has the opposite sign, occurs in spring, and is confined to the stratosphere. The negative Psw signal in the NAM under low solar irradiance conditions is primarily governed by enhanced vertical EP-flux divergence and a warmer polar region. The winter Psw signal under high solar irradiance conditions is associated with positive anomalies of the horizontal EP-flux divergence at 55°N–75°N and negative anomalies at 25°N–45°N, which corresponds to the positive NAM anomaly. The EP-flux divergence anomalies occur ~15 days ahead of the mean-flow changes. A significant equatorward shift of synoptic-scale Rossby wave breaking (RWB) near the tropopause is detected during January–March, corresponding to increased anticyclonic RWB and a decrease in cyclonic RWB. We suggest that the barotropic instability associated with asymmetric ozone in the upper stratosphere and the baroclinic instability associated with the polar vortex in the middle and lower stratosphere play a critical role for the winter signal and its downward propagation.

Modern diatom, cladocera, chironomid, and chrysophyte cyst assemblages as quantitative indicators for the reconstruction of past environmental conditions in the Alps. II. Nutrients

Surface sediments from 68 small lakes in the Alps and 9 well-dated sediment core samples that cover a gradient of total phosphorus (TP) concentrations of 6 to 520 μg TP l-1 were studied for diatom, chrysophyte cyst, cladocera, and chironomid assemblages. Inference models for mean circulation log10 TP were developed for diatoms, chironomids, and benthic cladocera using weighted-averaging partial least squares. After screening for outliers, the final transfer functions have coefficients of determination (r2, as assessed by cross-validation, of 0.79 (diatoms), 0.68 (chironomids), and 0.49 (benthic cladocera). Planktonic cladocera and chrysophytes show very weak relationships to TP and no TP inference models were developed for these biota. Diatoms showed the best relationship with TP, whereas the other biota all have large secondary gradients, suggesting that variables other than TP have a strong influence on their composition and abundance. Comparison with other diatom – TP inference models shows that our model has high predictive power and a low root mean squared error of prediction, as assessed by cross-validation.

Simulated winter circulation types in the North Atlantic and European region for preindustrial and glacial conditions

[1] Winter circulation types under preindustrial and glacial conditions are investigated and used to quantify their impact on precipitation. The analysis is based on daily mean sea level pressure fields of a highly resolved atmospheric general circulation model and focuses on the North Atlantic and European region. We find that glacial circulation types are dominated by patterns with an east-west pressure gradient, which clearly differs from the predominantly zonal patterns for the recent past. This is also evident in the frequency of occurrence of circulation types when projecting preindustrial circulation types onto the glacial simulations. The elevation of the Laurentide ice sheet is identified as a major cause for these differences. In areas of strong precipitation signals in glacial times, the changes in the frequencies of occurrence of the circulation types explain up to 60% of the total difference between preindustrial and glacial simulations.

Initiation of high-frequency oscillatory ventilation and its effects upon cerebral circulation in pigs: an experimental study

BACKGROUND: Current practice at high-frequency oscillatory ventilation (HFOV) initiation is a stepwise increase of the constant applied airway pressure to achieve lung recruitment. We hypothesized that HFOV would lead to more adverse cerebral haemodynamics than does pressure controlled ventilation (PCV) in the presence of experimental intracranial hypertension (IH) and acute lung injury (ALI) in pigs with similar mean airway pressure settings. METHODS: In 12 anesthetized pigs (24-27 kg) with IH and ALI, mean airway pressure (P(mean)) was increased (to 20, 25, 30 cm H(2)O every 30 min), either with HFOV or with PCV. The order of the two ventilatory modes (cross-over) was randomized. Mean arterial pressure (MAP), intracranial pressure (ICP), cerebral perfusion pressure (CPP), cerebral blood flow (CBF) (fluorescent microspheres), cerebral metabolism, transpulmonary pressures (P(T)), and blood gases were determined at each P(mean) setting. Our end-points of interest related to the cerebral circulation were ICP, CPP and CBF. RESULTS: CBF and cerebral metabolism were unaffected but there were no differences between the values for HFOV and PCV. ICP increased slightly (HFOV median +1 mm Hg, P<0.05; PCV median +2 mm Hg, P<0.05). At P(mean) setting of 30 cm H(2)O, CPP decreased during HFOV (median -13 mm Hg, P<0.05) and PCV (median -17 mm Hg, P<0.05) paralleled by a decrease of MAP (HFOV median -11 mm Hg, P<0.05; PCV median -13 mm Hg, P<0.05). P(T) increased (HFOV median +8 cm H(2)O, P<0.05; PCV median +8 cm H(2)O, P<0.05). Oxygenation improved and normocapnia maintained by HFOV and PCV. There were no differences between both ventilatory modes. CONCLUSIONS: In animals with elevated ICP and ALI, both ventilatory modes had effects upon cerebral haemodynamics. The effects upon cerebral haemodynamics were dependent of the P(T) level without differences between both ventilatory modes at similar P(mean) settings. HFOV seems to be a possible alternative ventilatory strategy when MAP deterioration can be avoided.

Influence of the sunspot cycle on the Northern Hemisphere wintertime circulation from long upper-air data sets

Here we present a study of the 11 yr sunspot cycle's imprint on the Northern Hemisphere atmospheric circulation, using three recently developed gridded upper-air data sets that extend back to the early twentieth century. We find a robust response of the tropospheric late-wintertime circulation to the sunspot cycle, independent from the data set. This response is particularly significant over Europe, although results show that it is not directly related to a North Atlantic Oscillation (NAO) modulation; instead, it reveals a significant connection to the more meridional Eurasian pattern (EU). The magnitude of mean seasonal temperature changes over the European land areas locally exceeds 1 K in the lower troposphere over a sunspot cycle. We also analyse surface data to address the question whether the solar signal over Europe is temporally stable for a longer 250 yr period. The results increase our confidence in the existence of an influence of the 11 yr cycle on the European climate, but the signal is much weaker in the first half of the period compared to the second half. The last solar minimum (2005 to 2010), which was not included in our analysis, shows anomalies that are consistent with our statistical results for earlier solar minima.

Greenland accumulation and its connection to the large-scale atmospheric circulation in ERA-Interim and paleoclimate simulations

Changes in Greenland accumulation and the stability in the relationship between accumulation variability and large-scale circulation are assessed by performing time-slice simulations for the present day, the preindustrial era, the early Holocene, and the Last Glacial Maximum (LGM) with a comprehensive climate model. The stability issue is an important prerequisite for reconstructions of Northern Hemisphere atmospheric circulation variability based on accumulation or precipitation proxy records from Greenland ice cores. The analysis reveals that the relationship between accumulation variability and large-scale circulation undergoes a significant seasonal cycle. As the contributions of the individual seasons to the annual signal change, annual mean accumulation variability is not necessarily related to the same atmospheric circulation patterns during the different climate states. Interestingly, within a season, local Greenland accumulation variability is indeed linked to a consistent circulation pattern, which is observed for all studied climate periods, even for the LGM. Hence, it would be possible to deduce a reliable reconstruction of seasonal atmospheric variability (e.g., for North Atlantic winters) if an accumulation or precipitation proxy were available that resolves single seasons. We further show that the simulated impacts of orbital forcing and changes in the ice sheet topography on Greenland accumulation exhibit strong spatial differences, emphasizing that accumulation records from different ice core sites regarding both interannual and long-term (centennial to millennial) variability cannot be expected to look alike since they include a distinct local signature. The only uniform signal to external forcing is the strong decrease in Greenland accumulation during glacial (LGM) conditions and an increase associated with the recent rise in greenhouse gas concentrations.

Outcome of standard and high-risk patients with acute anterior circulation stroke after stent retriever thrombectomy.

BACKGROUND AND PURPOSE Stent retrievers have become an important tool for the treatment of acute ischemic stroke. The aim of this study was to analyze outcome and complications in a large cohort of patients with stroke treated with the Solitaire stent retriever. The study also included patients who did not meet standard inclusion criteria for endovascular treatment: low or high baseline National Institutes of Health Stroke Scale score, ≥80 years of age, extensive ischemic signs in middle cerebral artery territory, and time from symptom onset to endovascular intervention>8 hours. METHODS Consecutive patients with acute anterior circulation stroke treated with the Solitaire FR were analyzed. Data on characteristics of endovascular interventions, complications, and clinical outcome were collected prospectively. Patients who met standard inclusion criteria were compared with those who did not. RESULTS A total of 227 patients were included. Mean age was 68.2±14.7 years, and median National Institutes of Health Stroke Scale score on admission was 16 (range, 2-36). Reperfusion was successful (thrombolysis in cerebral infarction, 2b-3) in 70.9%. Outcome was favorable (modified Rankin Scale, 0-2) in 57.7% of patients who met standard inclusion criteria and 30.3% of those who did not. The rates for symptomatic intracranial hemorrhage were 3.7% and 13.1%, for death 11.4% and 33.8%, and for symptomatic intraprocedural complications 2.5% and 4.8%, respectively. CONCLUSIONS Patients<80 years of age, without extensive pretreatment ischemic signs, and baseline National Institutes of Health Stroke Scale score≤30 had high rates of favorable outcome and low periprocedural complication rates after Solitaire thrombectomy. Successful reperfusion was also common in patients not fulfilling standard inclusion criteria, but worse clinical outcomes warrant further research with a special focus on optimal patient selection.

High Incorrect Use of the Standard Error of the Mean (SEM) in Original Articles in Three Cardiovascular Journals Evaluated for 2012.

RATIONALE In biomedical journals authors sometimes use the standard error of the mean (SEM) for data description, which has been called inappropriate or incorrect. OBJECTIVE To assess the frequency of incorrect use of SEM in articles in three selected cardiovascular journals. METHODS AND RESULTS All original journal articles published in 2012 in Cardiovascular Research, Circulation: Heart Failure and Circulation Research were assessed by two assessors for inappropriate use of SEM when providing descriptive information of empirical data. We also assessed whether the authors state in the methods section that the SEM will be used for data description. Of 441 articles included in this survey, 64% (282 articles) contained at least one instance of incorrect use of the SEM, with two journals having a prevalence above 70% and "Circulation: Heart Failure" having the lowest value (27%). In 81% of articles with incorrect use of SEM, the authors had explicitly stated that they use the SEM for data description and in 89% SEM bars were also used instead of 95% confidence intervals. Basic science studies had a 7.4-fold higher level of inappropriate SEM use (74%) than clinical studies (10%). LIMITATIONS The selection of the three cardiovascular journals was based on a subjective initial impression of observing inappropriate SEM use. The observed results are not representative for all cardiovascular journals. CONCLUSION In three selected cardiovascular journals we found a high level of inappropriate SEM use and explicit methods statements to use it for data description, especially in basic science studies. To improve on this situation, these and other journals should provide clear instructions to authors on how to report descriptive information of empirical data.

Minimized extracorporeal circulation does not impair cognitive brain function after coronary artery bypass grafting

OBJECTIVES Objective evaluation of the impact of minimized extracorporeal circulation (MECC) on perioperative cognitive brain function in coronary artery bypass grafting (CABG) by electroencephalogram P300 wave event-related potentials and number connection test (NCT) as metrics of cognitive function. METHODS Cognitive brain function was assessed in 31 patients in 2013 with a mean age of 65 years [standard deviation (SD) 10] undergoing CABG by the use of MECC with P300 auditory evoked potentials (peak latencies in milliseconds) directly prior to intervention, 7 days after and 3 months later. Number connection test, serving as method of control, was performed simultaneously in all patients. RESULTS Seven days following CABG, cognitive P300 evoked potentials were comparable with preoperative baseline values [vertex (Cz) 376 (SD 11) ms vs 378 (18) ms, P = 0.39; frontal (Fz) 377 (11) vs 379 (21) ms, P = 0.53]. Cognitive brain function at 3 months was compared with baseline values [(Cz) 376 (11) ms vs 371 (14 ms) P = 0.09; (Fz) 377 (11) ms vs 371 (15) ms, P = 0.04]. Between the first postoperative measurement and 3 months later, significant improvement was observed [(Cz) 378 (18) ms vs 371 (14) ms, P = 0.03; (Fz) 379 (21) vs 371 (15) ms, P = 0.02]. Similar clearly corresponding patterns could be obtained via the number connection test. Results could be confirmed in repeated measures analysis of variance for Cz (P = 0.05) and (Fz) results (P = 0.04). CONCLUSIONS MECC does not adversely affect cognitive brain function after CABG. Additionally, these patients experience a substantial significant cognitive improvement after 3 months, evidentiary proving that the concept of MECC ensures safety and outcome in terms of brain function.

Minimized Extracorporeal Circulation does not impair cognitive brain function after coronary artery bypass grafting

Gebiet: Chirurgie Abstract: Minimized Extracorporeal Circulation does not impair cognitive brain function after coronary artery bypass grafting – – Objectives – Objective evaluation of the impact of minimized extracorporeal circulation (MECC) on perioperative cognitive brain function in coronary bypass grafting (CABG) by Electroencephalogram (EEG) P 300 wave event related potentials (ERP) and number connection test ( NCT) as metrics of cognitive function. – – Methods – Cognitive brain function was assessed in 31 patients with a mean age of 65y (Standard Deviation/SD 10) undergoing coronary artery bypass grafting (CABG) by the use of MECC with P300 auditory evoked potentials (peak latencies in milliseconds [ms]) directly prior to intervention, 7 days after and 3 month later. Number connection test (NCT), serving as method of control, was performed simultaneously in all patients. – – Results – Seven days following CABG, cognitive P300 evoked potentials were comparable to preoperative baseline values (vertex [Cz] 376 (SD 11) ms vs. 378 (18) ms, p=0.39, frontal [Fz] 377 (11) vs. 379 (21) ms, p=0.53). Cognitive brain function showed at 3 months compared to baseline values ([Cz] 376 (11) ms vs. 371 (14 ms) p=0.09, [Fz] 377 (11) ms vs. 371 (15) ms, p=0.04. Between the first postoperative measurement and 3 months later, significant improvement was observed ([Cz] 378 (18) ms vs. 371 (14) ms, p=0.03, [Fz] 379 (21) vs. 371 (15) ms, p=0.02). Similar clearly corresponding patterns could be obtained via number connection test. Results could be confirmed in repeated measures analysis of variance for Cz (p = 0.05) and (Fz) results (p = 0.04). – – Conclusions

Clinical prediction of large vessel occlusion in anterior circulation stroke: mission impossible?

Simple clinical scores to predict large vessel occlusion (LVO) in acute ischemic stroke would be helpful to triage patients in the prehospital phase. We assessed the ability of various combinations of National Institutes of Health Stroke Scale (NIHSS) subitems and published stroke scales (i.e., RACE scale, 3I-SS, sNIHSS-8, sNIHSS-5, sNIHSS-1, mNIHSS, a-NIHSS items profiles A-E, CPSS1, CPSS2, and CPSSS) to predict LVO on CT or MR arteriography in 1085 consecutive patients (39.4 % women, mean age 67.7 years) with anterior circulation strokes within 6 h of symptom onset. 657 patients (61 %) had an occlusion of the internal carotid artery or the M1/M2 segment of the middle cerebral artery. Best cut-off value of the total NIHSS score to predict LVO was 7 (PPV 84.2 %, sensitivity 81.0 %, specificity 76.6 %, NPV 72.4 %, ACC 79.3 %). Receiver operating characteristic curves of various combinations of NIHSS subitems and published scores were equally or less predictive to show LVO than the total NIHSS score. At intersection of sensitivity and specificity curves in all scores, at least 1/5 of patients with LVO were missed. Best odds ratios for LVO among NIHSS subitems were best gaze (9.6, 95 %-CI 6.765-13.632), visual fields (7.0, 95 %-CI 3.981-12.370), motor arms (7.6, 95 %-CI 5.589-10.204), and aphasia/neglect (7.1, 95 %-CI 5.352-9.492). There is a significant correlation between clinical scores based on the NIHSS score and LVO on arteriography. However, if clinically relevant thresholds are applied to the scores, a sizable number of LVOs are missed. Therefore, clinical scores cannot replace vessel imaging.

A new, fast and flexible radiative transfer method for Venus general circulation models

We present a new radiation scheme for the Oxford Planetary Unified Model System for Venus, suitable for the solar and thermal bands. This new and fast radiative parameterization uses a different approach in the two main radiative wavelength bands: solar radiation (0.1-5.5 mu m) and thermal radiation (1.7-260 mu m). The solar radiation calculation is based on the delta-Eddington approximation (two-stream-type) with an adding layer method. For the thermal radiation case, a code based on an absorptivity/emissivity formulation is used. The new radiative transfer formulation implemented is intended to be computationally light, to allow its incorporation in 3D global circulation models, but still allowing for the calculation of the effect of atmospheric conditions on radiative fluxes. This will allow us to investigate the dynamical-radiative-microphysical feedbacks. The model flexibility can be also used to explore the uncertainties in the Venus atmosphere such as the optical properties in the deep atmosphere or cloud amount. The results of radiative cooling and heating rates and the global-mean radiative-convective equilibrium temperature profiles for different atmospheric conditions are presented and discussed. This new scheme works in an atmospheric column and can be easily implemented in 3D Venus global circulation models. (C) 2014 Elsevier Ltd. All rights reserved.