Rapid climate change during the Weichselian Lateglacial in Ireland: Chironomid-inferred summer temperatures from Fiddaun, Co. Galway

A lacustrine sediment core from Fiddaun, western Ireland was studied to reconstruct summer temperature changes during the Weichselian Lateglacial. This site is located close to the Atlantic Ocean; and so is potentially sensitive to climatic changes associated with changes in ocean circulation. The record, comprising the end of the Weichselian Pleniglacial to the early Holocene, was analysed for fossil chironomids, lithology, and oxygen and carbon isotopes in the sedimentary carbonates. These proxies clearly show rapid warming at the onset of the Lateglacial Interstadial, relatively high summer temperatures during the Interstadial, pronounced cooling during the Younger Dryas, and subsequent warming at the transition to the Holocene. Chironomid-inferred mean July air temperatures for the Interstadial are ~12.5–14.5 °C, ~7.5 °C for the Younger Dryas, and ~15.0 °C for the early Holocene. Furthermore, this research provides evidence for at least two cold events during the Interstadial. These more moderate temperature oscillations can be correlated to Greenland Interstadial events 1b and 1d, on the basis of the age-depth model for the Fiddaun sequence. Based on multiple proxies, the first cold oscillation (GI-1d) was the more severe of the two in Ireland.

Climatic and environmental changes during the Weichselian Lateglacial Interstadial in the Weerterbos region, the Netherlands

Lake sediment records from the Weerterbos region, in the southern Netherlands, were studied to reconstruct summer temperature and environmental changes during the Weichselian Lateglacial Interstadial. A sediment core obtained from a small lacustrine basin was analysed for multiple proxies, including lithological changes, oxygen isotopes of bulk carbonates, pollen and chironomids. It was found that the oxygen isotope record differed strongly from the other proxies. Based on a comparison with three additional lake sediment records from the same region, it emerged that the oxygen isotope records were strongly affected by local environmental conditions, impeding the distinction of a regional palaeoclimate signal. The chironomid-inferred July air temperature reconstruction produced inferred interstadial temperatures ranging between ∼15° and 18°C, largely consistent with previously published results from the northern part of the Netherlands. A temporary regressive phase in the pollen record, which can be tentatively correlated with the Older Dryas, preceded the expansion of birch woodland. Despite differences between the four pollen records from the Weerterbos region, a comparable regressive vegetation phase that was possibly the result of a shift to drier conditions could be discerned in all of the profiles. In addition, a temporary temperature decline of ∼1.5°C was inferred from the chironomid record during this regressive phase. The multi-proxy approach used here enabled a direct comparison of inferred changes in temperature, vegetation and environmental conditions at an individual site, while the multi-site approach provided insight into the factors influencing the pollen and isotope records from these small-scale depressions.

Validation of climate model-inferred regional temperature change for late-glacial Europe

Comparisons of climate model hindcasts with independent proxy data are essential for assessing model performance in non-analogue situations. However, standardized palaeoclimate data sets for assessing the spatial pattern of past climatic change across continents are lacking for some of the most dynamic episodes of Earth’s recent past. Here we present a new chironomid-based palaeotemperature dataset designed to assess climate model hindcasts of regional summer temperature change in Europe during the late-glacial and early Holocene. Latitudinal and longitudinal patterns of inferred temperature change are in excellent agreement with simulations by the ECHAM-4 model, implying that atmospheric general circulation models like ECHAM-4 can successfully predict regionally diverging temperature trends in Europe, even when conditions differ significantly from present. However, ECHAM-4 infers larger amplitudes of change and higher temperatures during warm phases than our palaeotemperature estimates, suggesting that this and similar models may overestimate past and potentially also future summer temperature changes in Europe.

Clinical performance of a sutureless aortic bioprosthesis: five-year results of the 3f Enable long-term follow-up study.

OBJECTIVE Sutureless valves are designed to facilitate surgical implantation, including less-invasive techniques in aortic valve replacement, by maintaining surgical precision of implantation compared with transcatheter techniques. Long-term clinical experience with sutureless valves is lacking. We report the 5-year follow-up results of an international, prospective, multicenter study evaluating the clinical performance and safety of the 3f Enable valve (Medtronic Inc, Minneapolis, Minn). METHODS Between March 2007 and December 2009, 141 patients (54 male; mean age, 76.1±5.7 years) undergoing aortic valve replacement with the 3f Enable valve were enrolled in 10 European sites. The mean follow-up was 2.76 years (range, 2 days to 5.1 years; total, 388.7 patient-years). Echocardiographic valvular hemodynamic and morphologic analyses were performed by an independent core laboratory. RESULTS The mean systolic gradient was 10.4±4.4 mm Hg at discharge and 7.7±4.1 mm Hg at 5 years. The mean effective orifice area was 1.7±0.5 cm2 at discharge and 1.6±0.2 cm2 at 5 years. Freedom from all-cause and valve-related mortality was 87.6%±2.9% and 96.8%±1.6% at 1 year (113 patients at risk) and 77.0%±7.5% and 93.8%±4.8% at 5 years (24 patients at risk), respectively. Six patients underwent reoperation (4 because of major paravalvular leakage and 2 because of endocarditis). Freedom from reoperation was 95.4%±1.9% at 1 year and 95.4%±6.1% at 5 years. No structural valve deterioration occurred during the follow-up period. CONCLUSIONS The sutureless 3f Enable valve represents a safe and effective treatment for aortic valve stenosis, providing an excellent hemodynamic profile. This study represents the longest follow-up study for a sutureless bioprosthesis. Sutureless valves may become an option for all patients with indicated biological aortic valve replacement.

The sutureless aortic valve at 1 year: A large multicenter cohort study

OBJECTIVE Sutureless aortic valve replacement (AVR) offers an alternative to standard AVR in aortic stenosis. This prospective, single-arm study aimed to demonstrate safety and effectiveness of a bovine pericardial sutureless aortic valve at 1 year. METHODS From February 2010 to September 2013, 658 patients (mean age 78.3 ± 5.6 years; 40.0% octogenarian; 64.4% female; mean Society of Thoracic Surgeons score 7.2 ± 7.4) underwent sutureless AVR in 25 European centers. Concomitant cardiac procedures were performed in 29.5% and minimally invasive cardiac surgery in 33.3%. RESULTS One-year site-reported event rates were 8.1% for all-cause mortality, 4.5% for cardiac mortality, 3.0% for stroke, 1.9% for valve-related reoperation, 1.4% for endocarditis, and 0.6% for major paravalvular leak. No valve thrombosis, migration, or structural valve deterioration occurred. New York Heart Association class improved at least 1 level in 77.5% and remained stable (70.4% New York Heart Association class I or II at 1 year). Mean effective orifice area was 1.5 ± 0.4 cm(2); pressure gradient was 9.2 ± 5.0 mm Hg. Left ventricular mass decreased from 138.5 g/m(2) before surgery to 115.3 g/m(2) at 1 year (P < .001). Echocardiographic core laboratory findings confirmed that paravalvular leak was rare and remained stable during follow-up. CONCLUSIONS The Perceval sutureless valve resulted in low 1-year event rates in intermediate-risk patients undergoing AVR. New York Heart Association class improved in more than three-quarters of patients and remained stable. These data support the safety and efficacy to 1 year of the Perceval sutureless valve in this intermediate-risk population.