892 research outputs found
The impact of Arctic sea ice loss on mid-Holocene climate.
Mid-Holocene climate was characterized by strong summer solar heating that decreased Arctic sea ice cover. Motivated by recent studies identifying Arctic sea ice loss as a key driver of future climate change, we separate the influences of Arctic sea ice loss on mid-Holocene climate. By performing idealized climate model perturbation experiments, we show that Arctic sea ice loss causes zonally asymmetric surface temperature responses especially in winter: sea ice loss warms North America and the North Pacific, which would otherwise be much colder due to weaker winter insolation. In contrast, over East Asia, sea ice loss slightly decreases the temperature in early winter. These temperature responses are associated with the weakening of mid-high latitude westerlies and polar stratospheric warming. Sea ice loss also weakens the Atlantic meridional overturning circulation, although this weakening signal diminishes after 150-200 years of model integration. These results suggest that mid-Holocene climate changes should be interpreted in terms of both Arctic sea ice cover and insolation forcing
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Mid-Holocene Northern Hemisphere warming driven by Arctic amplification.
The Holocene thermal maximum was characterized by strong summer solar heating that substantially increased the summertime temperature relative to preindustrial climate. However, the summer warming was compensated by weaker winter insolation, and the annual mean temperature of the Holocene thermal maximum remains ambiguous. Using multimodel mid-Holocene simulations, we show that the annual mean Northern Hemisphere temperature is strongly correlated with the degree of Arctic amplification and sea ice loss. Additional model experiments show that the summer Arctic sea ice loss persists into winter and increases the mid- and high-latitude temperatures. These results are evaluated against four proxy datasets to verify that the annual mean northern high-latitude temperature during the mid-Holocene was warmer than the preindustrial climate, because of the seasonally rectified temperature increase driven by the Arctic amplification. This study offers a resolution to the "Holocene temperature conundrum", a well-known discrepancy between paleo-proxies and climate model simulations of Holocene thermal maximum
A Simple Method for Simulating Horizontal Ozone Concentration Fields over Coastal Areas: A Case Study of the Seoul Metropolitan Area, Korea
This paper describes a simple semi-empirical photo chemical simulation method to generate horizontal ozone (O3) concentration fields over coastal areas. Based on a simple semi-empirical photochemical reaction model (SEGRS), consisting of a simple photochemical reaction set and a diagnostic wind model, aggregated VOC emission strength is empirically scaled from measured photochemical gas phase concentrations of (O3-2NO-NO2) against cumulative actinic light flux for the case of relatively weak off-shore geostrophic wind at 850 hPa in sum mer. This scaled emission rate for volatile organic compounds (VOCs) is equally applied to horizontal O3 concentration simulation under on-shore synoptic conditions, and results are com pared with observations. The results indicate that spatial distribution patterns and temporal variations of spatially aver aged ground level ozone concentrations are reasonably well simulated. In addition, from the more than 100 box-form SEGRS simulations, close agreement between simulated and ob served daily maximum O3 concentrations suggests that the semi empirical SEGRS model has great potential in getting horizontal ozone distribution pat terns. This indicates that this simple semi-empirical approach to the simulation of O3 concentration pat terns using SEGRS makes for an easy alternative method in multi-year simulation for impact studies of O3 concentrations by lowering heavy computational cost
Efficacy evaluation of combination vaccine of recombinant C-terminal fragments of ApxIA, ApxIIA and ApxIIIA in piglets
The efficacy of the combination vaccine of the individual C-terminal fragments of ApxIA, ApxIIA and ApxIIIA of Actinobacillus pleuropneumoniae (APP) was evaluated in piglets. Twenty piglets were divided equally into 2 groups (n=10). All piglets were intramuscularly primed at 4 week-of-age (0 week post prime inoculation (WPPI)) and were intramuscularly boosted at 6 week-of-age (2 WPPI). Group A piglets were inoculated with sterile PBS and group B piglets were inoculated with the combination vaccine. Concentrations of each of the C-terminal fragment-specific IgG as determined by ELISA were significantly higher in group B than in group A from 2 WPPI until the end of this study. Clinical signs were observed from only 10% of group B piglets after the challenge with the mixture of APP serotypes 1, 2 and 5 at 4 WPPI, while 50% of group A piglets were protected against APP infections. Overall, intramuscular inoculation with the vaccine candidate can efficiently protect piglets against APP infection
Mechanisms of an extraordinary East Asian summer monsoon event in July 2011
Previous studies have demonstrated that the strong East Asian summer monsoon results mainly from the westward intensification of the North Pacific subtropical high (NPSH), or equivalently, the enhancement of the western North Pacific subtropical high. However, during early July in 2011 a strong southerly or southeasterly moist flow gave rise to a large amount of precipitation over southwestern Japan and Korea and anomalous dry conditions over central China because of the extraordinary intensification of the NPSH to the north. The formation of the anomalous high that occurred to the east of central Japan during early July is very rare, and its physical mechanisms are investigated in this study. The regressed circulation anomalies and wave-activity flux vectors for July 2011 and data from the previous 32 years show that two teleconnection patterns due to Rossby wave trains are the most important mechanisms: Rossby wave propagation from the eastern North Atlantic and western Europe to East Asia following the North Eurasian jet and East Asian jet in the upper level, and northward propagation of Rossby waves forced by diabatic heating over the western North Pacific (WNP) region in the lower level. This simultaneous forcing of a significant negative phase of the summertime North Atlantic Oscillation in the higher latitudes and enhanced diabatic heating over the subtropical WNP is found to be the cause of the abnormal development of the anomalous high to the east of central Japan, resulting in extremely wet conditions in Korea and southern Japan and dry conditions in southern China
Efficacy Evaluation of Combination Vaccine of Recombinant C-Terminal Fragments of ApxIA, ApxIIA and ApxIIIA in Piglets (Penilaian Kemujaraban Gabungan Vaksin Rekombinan Terminal-C Serpihan ApxIA, ApxIIA dan ApxIIIA pada Anak Babi)
ABSTRACT The efficacy of the combination vaccine of the individual C-terminal fragments o
Atrasentan and renal events in patients with type 2 diabetes and chronic kidney disease (SONAR): a double-blind, randomised, placebo-controlled trial
Background: Short-term treatment for people with type 2 diabetes using a low dose of the selective endothelin A receptor antagonist atrasentan reduces albuminuria without causing significant sodium retention. We report the long-term effects of treatment with atrasentan on major renal outcomes. Methods: We did this double-blind, randomised, placebo-controlled trial at 689 sites in 41 countries. We enrolled adults aged 18–85 years with type 2 diabetes, estimated glomerular filtration rate (eGFR)25–75 mL/min per 1·73 m 2 of body surface area, and a urine albumin-to-creatinine ratio (UACR)of 300–5000 mg/g who had received maximum labelled or tolerated renin–angiotensin system inhibition for at least 4 weeks. Participants were given atrasentan 0·75 mg orally daily during an enrichment period before random group assignment. Those with a UACR decrease of at least 30% with no substantial fluid retention during the enrichment period (responders)were included in the double-blind treatment period. Responders were randomly assigned to receive either atrasentan 0·75 mg orally daily or placebo. All patients and investigators were masked to treatment assignment. The primary endpoint was a composite of doubling of serum creatinine (sustained for ≥30 days)or end-stage kidney disease (eGFR <15 mL/min per 1·73 m 2 sustained for ≥90 days, chronic dialysis for ≥90 days, kidney transplantation, or death from kidney failure)in the intention-to-treat population of all responders. Safety was assessed in all patients who received at least one dose of their assigned study treatment. The study is registered with ClinicalTrials.gov, number NCT01858532. Findings: Between May 17, 2013, and July 13, 2017, 11 087 patients were screened; 5117 entered the enrichment period, and 4711 completed the enrichment period. Of these, 2648 patients were responders and were randomly assigned to the atrasentan group (n=1325)or placebo group (n=1323). Median follow-up was 2·2 years (IQR 1·4–2·9). 79 (6·0%)of 1325 patients in the atrasentan group and 105 (7·9%)of 1323 in the placebo group had a primary composite renal endpoint event (hazard ratio [HR]0·65 [95% CI 0·49–0·88]; p=0·0047). Fluid retention and anaemia adverse events, which have been previously attributed to endothelin receptor antagonists, were more frequent in the atrasentan group than in the placebo group. Hospital admission for heart failure occurred in 47 (3·5%)of 1325 patients in the atrasentan group and 34 (2·6%)of 1323 patients in the placebo group (HR 1·33 [95% CI 0·85–2·07]; p=0·208). 58 (4·4%)patients in the atrasentan group and 52 (3·9%)in the placebo group died (HR 1·09 [95% CI 0·75–1·59]; p=0·65). Interpretation: Atrasentan reduced the risk of renal events in patients with diabetes and chronic kidney disease who were selected to optimise efficacy and safety. These data support a potential role for selective endothelin receptor antagonists in protecting renal function in patients with type 2 diabetes at high risk of developing end-stage kidney disease. Funding: AbbVie
MUSiC : a model-unspecific search for new physics in proton-proton collisions at root s=13TeV
Results of the Model Unspecific Search in CMS (MUSiC), using proton-proton collision data recorded at the LHC at a centre-of-mass energy of 13 TeV, corresponding to an integrated luminosity of 35.9 fb(-1), are presented. The MUSiC analysis searches for anomalies that could be signatures of physics beyond the standard model. The analysis is based on the comparison of observed data with the standard model prediction, as determined from simulation, in several hundred final states and multiple kinematic distributions. Events containing at least one electron or muon are classified based on their final state topology, and an automated search algorithm surveys the observed data for deviations from the prediction. The sensitivity of the search is validated using multiple methods. No significant deviations from the predictions have been observed. For a wide range of final state topologies, agreement is found between the data and the standard model simulation. This analysis complements dedicated search analyses by significantly expanding the range of final states covered using a model independent approach with the largest data set to date to probe phase space regions beyond the reach of previous general searches.Peer reviewe