Diatom-based evidence for abrupt climate changes during the Late Glacial in the Southern Carpathian Mountains

Abstract A high-resolution paleolimnological record from Lake Brazi (TDB-1; 45°23’47″N, 22°54’06″E, 1740 m a.s.l.), a small, glacial lake in the Retezat (South Carpathian Mountains, Romania) provides a sensitive record of the impacts of late glacial climatic change on siliceous algal assemblages. The sequence, ranging from 15,700 cal yr BP to 9500 cal yr BP, suggests that the most significant changes in diatom assemblages took place at 12,800 and 10,400 cal yr BP, when alkaliphilous fragilarioid taxa were replaced by acidophilous diatoms. Altogether eight zones were distinguished with sharp and rapid changes of diatom assemblages. The paper discusses the application of siliceous algae in multi-proxy paleolimnological analyses, demonstrates the advantages and disadvantages of this proxy and presents the story of floristic discovery of unique diatom assemblages, the closest recent analogs of which are found in the arctic region

Radiocarbon chronology of glacial lake sediments in the Retezat Mts (South Carpathians, Romania): a window to Late Glacial and Holocene climatic and paleoenvironmental changes

Abstract the Retezat Mountains, this study discusses radiocarbon chronology and sediment accumulation rate changes in two sediment profiles in relation to lithostratigraphy, organic content, biogenic silica and major pollenstratigraphic changes. A total of 25 radiocarbon dates were obtained from sediments of two lakes, Lake Brazi (TDB-1; 1740 m a.s.l.) and Lake Gales (Gales-3; 1990 m a.s.l.). Age-depth modeling was performed on TDB-1 using calibrated age ranges from BCal and various curve-fitting methods in psimpoll. Our results suggest that sediment accumulation began between 15,124–15,755 cal yr BP in both lakes and was continuous throughout the Late Glacial and Holocene. We demonstrated that local ecosystem productivity showed delayed response to Late Glacial and Early Holocene climatic changes in the subalpine and alpine zones most likely attributable to the cooling effect of remnant glaciers and meltwater input. However, regional vegetation response was without time lag and indicated forestation and warming at 14,450 and 11,550 cal yr BP, and cooling at ca. 12,800 cal yr BP. In the Holocene one major shift was detected, starting around 6300 cal yr BP and culminating around 5200 cal yr BP. The various proxies suggested summer cooling, shorter duration of the winter ice-cover season and/or increasing size of the water body, probably in response to increasing available moisture

Limnological changes in South Carpathian glacier-formed lakes (Retezat Mountains, Romania) during the Late Glacial and the Holocene: A synthesis

Remains of aquatic biota preserved in mountain lake sediments provide an excellent tool to study lake ecosystem responses to past climate change. In the PROLONG project a multi-proxy study was performed on sediments of glacier-formed lakes from the Retezat Mountains, Southern Carpathians (Romania). The studied lakes (Lake Brazi and Gales) are situated on the northern slope of the mountain at different altitudes (1740 m and 1990 m a.s.l.). Our main objectives were 1) to describe the main limnological changes in these lakes during the last ca. 15,000 years and 2) to summarize the environmental history of the studied lakes based on taxonomical and functional patterns of the biological proxies. For this synthesis we used the results of diatom and chironomid analyses, and indirect biotic and abiotic parameters, including sediment organic matter (LOI) content, geochemical element concentrations (Al, Ca, S, Sr) and biogenic silica content. Using multivariate numerical approaches we analysed changes in the assemblage structure of siliceous algae and chironomids, compared temporal patterns among proxies, examined the relationship between potential driving factors, chironomid and diatom assemblage changes and identified paleolimnological phases of the lake successions. Changes in assemblage composition and aquatic ecosystem state apparently followed summer insolation, local climatic conditions and local productivity changes driven by these. Diatom and chironomid assemblages generally changed in a similar direction and at a similar time within a lake, but differed to some extent between Lake Brazi and Gales. At both lakes the strongest variations were observed in the Late Glacial and the first half of the Holocene. The strongest Holocene assemblage changes took place in the earliest Holocene in Lake Brazi, but extended into the mid-Holocene in Lake Gales, following long-term insolation changes and climatic changes. In addition, three common zone boundaries were identified: at ca. 14,200 and at ca. 6500 cal yr BP for every records and at ca. 3100 cal yr BP for diatom records in both of the lakes and for the chironomid record of Lake Brazi. This multi-proxy synthesis provides comprehensive data that increase our understanding of the past variability of lake ecosystem functioning and biodiversity in East-Central Europe. Keyword

The effect of priority setting decisions for new cancer drugs on medical oncologists' practice in Ontario: a qualitative study

<p>Abstract</p> <p>Background</p> <p>Health care policies, including drug-funding policies, influence physician practice. Funding policies are especially important in the area of cancer care since cancer is a leading cause of death that is responsible for a significant level of health care expenditures. Recognizing the rising cost of cancer therapies, Cancer Care Ontario (CCO) established a funding process to provide access to new, effective agents through a "New Drug Funding Program" (NDFP). The purpose of this study is to describe oncologists' perceptions of the impact of NDFP priority setting decisions on their practice.</p> <p>Methods</p> <p>This is a qualitative study involving semi-structured, in-depth interviews with 46 medical oncologists in Ontario. Oncologists were asked to describe the impact of CCO's NDFP drug funding decisions on their practice. Analysis of interview transcripts commenced with data collection.</p> <p>Results</p> <p>Our key finding is that many of the medical oncologists who participated in this study did not accept limits when policy decisions limit access to cancer drugs they feel would benefit their patients. Moreover, overcoming those limits had a significant impact on oncologists' practice in terms of how they spend their time and energy and their relationship with patients.</p> <p>Conclusion</p> <p>When priority setting decisions limit access to cancer medications, many oncologists' efforts to overcome those limits have a significant impact on their practice. Policy makers need to seriously consider the implications of their decisions on physicians, who may go to considerable effort to circumvent their policies in the name of patient advocacy.</p

Biodiversity responses to Lateglacial climate change in the subdecadally-resolved record of Lake Hämelsee (Germany)

Anthropogenically-driven climate warming and land use change are the main causes of an ongoing decrease in global biodiversity. It is unclear how ecosystems, particularly freshwater habitats, will respond to such continuous and potentially intensifying disruptions. Here we analyse how different components of terrestrial and aquatic ecosystems responded to natural climate change during the Lateglacial. By applying a range of analytical techniques (sedimentology, palaeoecology, geochemistry) to the well-dated sediment archive from Lake Hämelsee (Germany), we show evidence for vegetation development, landscape dynamics and aquatic ecosystem change typical for northwest Europe during the Lateglacial. By particularly focussing on periods of abrupt climate change, we determine the timing and duration of changes in biodiversity in response to external forcing. We show that onsets of changes in biodiversity indicators (e.g. diatom composition, Pediastrum concentrations) lag changes in environmental records (e.g. loss-on-ignition) by a few decades, particularly at the Allerød/ Younger Dryas transition. Most biodiversity indicators showed transition times of 10–50 years, whereas environmental records typically showed a 50–100 year long transition. In some cases, transition times observed for the compositional turnover or productivity records were up to 185 years, which could have been the result of the combined effects of direct (e.g. climate) and indirect (e.g. lake stratification) drivers of ecosystem change. Our results show differences in timing and duration of biodiversity responses to external disturbances, suggesting that a multi-decadal view needs to be taken when designing effective conservation management of freshwater ecosystems under current global warming

Using linear discriminant analysis (LDA) of bulk lake sediment geochemical data to reconstruct lateglacial climate changes in the South Carpathian Mountains

A multi-proxy approach is widely used for reconstructing climatic change in alpine lake sediments. This study applied bulk sediment geochemistry to reconstruct lateglacial and early Holocene climatic change in a glacial lake (Lake Brazi, 1740 m a.s.l.) in the Retezat Mts. (South Carpathians, Romania). The lowermost 1 m part of a 4.9-m long sediment core, covering the period between 9950 and 15,750 cal BP, was used for high resolution bulk analysis of major elements (Al2O3, SiO2, TiO2, CaO, MgO, K2O, Na2O, Fe2O3, MnO, SO3). Linear discriminant analysis (LDA) was used to compare a priori classified main chemical groups. Subsamples from the core were priory ordered to “warm” and “cold” groups respectively, according to their age and evidence of cold and warm events in the record, as suggested by proxy correlation with the lateglacial event stratigraphy of North Greenland Ice Core Project (NGRIP). The discriminant function was calculated using concentrations of Al2O3, TiO2, CaO, MgO, K2O, Na2O, Fe2O3, and MnO after log ratio transformation. Loss-on-ignition, silicon and sulphur concentrations were not used for the discriminant analysis, but regarded as comparison proxies for checking up the validity of outputs. Sediments deposited during “cold” and “warm” events were separated significantly by the LDA function; 85.1% of the originally grouped cases were correctly classified under the LDA analysis. The calculated discriminant scores indicated four “cold” and four “warm” events. Sediments ordered into the “warm” group contained larger amounts of organic matter and sulphur, while sediment samples of the “cold” group were characterized by the overall predominance of major oxides bound into inorganic silicates. The discriminant scores showed strong correlation with the NGRIP d18O data (r ¼ 0.8135) and with the pollen percentage sum of trees and shrubs (r ¼ 0.9460). Loss-on-ignition showed a somehow weaker, but still conclusive linear relationship with the discriminant scores (r ¼ 0.7505). Discriminant analyses of bulk sediment major oxide chemical data may be a useful tool to identify the impact of climatic events upon the nature and composition of materials delivered to a lake basin

Palaeohydrological changes during the mid and late Holocene in the Carpathian area, central-eastern Europe

Multi-proxy, high-resolution analyses (lithological, geochemical, environmental magnetism) anchored by 22 14C dates, of a 5.53 m long sediment core from Lake Ighiel (Romanian Carpathians, central-eastern Europe) allowed the reconstruction of key local, catchment-lacustrine dynamics and an appraisal of palaeohydrological and palaeoclimatic gradients acting regionally over the last 6000 years. The first sedimentological phase of the record from 6030 to 4200 cal yr BP is characterised by low productivity and high detrital input indicating surface runoff processes due to enhanced rainfall. This interpretation is in agreement with other hydrological reconstructions reporting increased precipitation also in CE Europe, NE Mediterranean and also inferred summer and winter latitudinal temperature gradients (LTG) (as defined by Davis and Brewer, 2009), showing a strong connectivity between basin-lacustrine dynamics and the establishment of the dominant, Atlantic atmospheric circulation pattern in the area. The lacustrine system was more stable between 4200 and 2500 cal yr BP when clastic inputs diminished and biological productivity increased. During this interval, the coherence of Lake Ighiel's multi-century detrital events, identified in a range of proxy-data (albeit different in frequency and magnitude), with flood activity in central Europe (the Alps) suggests a common moisture forcing (Atlantic and periodically Mediterranean influences). In contrast, different reconstructions from the NE Mediterranean indicate a distinct NW-SE hydro-climatic gradient. A more complex and variable trend is depicted in Lake Ighiel sedimentation during the last ~ 2500 years showing a variable detrital trend likely reflecting an intriguing hydrological pattern which is in agreement with intervals of increased aridity phases during a generally moister period. Comparing our sedimentological results with published pollen records from the nearby area clearly indicates anthropogenic imprints during the Dacian-Roman Period and especially from the Middle Ages towards the present. The ~ 6000-year long sedimentary record of Lake Ighiel contributes to our understanding of mid and late Holocene palaeohydrological changes in the Carpathians and highlights the importance of latitudinal gradients in driving hydrological variability in continental Europe

No mutation but high mRNA expression of Coxsackie-Adenovirus Receptor was observed in both dilated and ischemic cardiomyopathy

The most common causes of acute myocarditis and the possible consequence of dilated cardiomyopathy are virus infections. The receptor of the two most common viruses connected to these myocardial diseases was identified as Coxsackie-Adenovirus Receptor. The purpose of this study was to assess Coxsackie-Adenovirus Receptor mRNA expression in the myocardium and search for mutations in the Coxsackie-Adenovirus Receptor gene to compare dilated, inflammatory and ischemic cardiomyopathy with control group. All the myocardial samples were obtained from 35 explanted hearts during heart transplantation, than DNA and RNA were isolated from the muscle samples. cDNA was generated from RNA using reverse transcription, and real-time PCR was performed with relative quantification by beta-actin gene as endogenous control. Using DNA extracted from the myocardial samples, we sequenced all the seven exons of the Coxsackie-Adenovirus Receptor gene. Coxsackie-Adenovirus Receptor mRNA expression was higher in both ischemic and dilated cardiomyopathy groups than in inflammatory cardiomyopathy and healthy control groups. Sequencing of CAR gene showed no sign of mutation. Therefore, the sequences result of CAR exons did not show any mutation or polymorphism, that explains a determinant role of CAR in dilated or ischemic CM. Our results suggest that high mRNA expression of Coxsackie-Adenovirus Receptor may support its role in regeneration of the damaged myocardium rather than having any role in viral mediated heart disease