RESUMO
We present quantitative reconstructions of regional vegetation cover in north-western Europe, western Europe north of the Alps, and eastern Europe for five time windows in the Holocene [around 6k, 3k, 0.5k, 0.2k, and 0.05k calendar years before present (bp)] at a 1° × 1° spatial scale with the objective of producing vegetation descriptions suitable for climate modelling. The REVEALS model was applied on 636 pollen records from lakes and bogs to reconstruct the past cover of 25 plant taxa grouped into 10 plant-functional types and three land-cover types [evergreen trees, summer-green (deciduous) trees, and open land]. The model corrects for some of the biases in pollen percentages by using pollen productivity estimates and fall speeds of pollen, and by applying simple but robust models of pollen dispersal and deposition. The emerging patterns of tree migration and deforestation between 6k bp and modern time in the REVEALS estimates agree with our general understanding of the vegetation history of Europe based on pollen percentages. However, the degree of anthropogenic deforestation (i.e. cover of cultivated and grazing land) at 3k, 0.5k, and 0.2k bp is significantly higher than deduced from pollen percentages. This is also the case at 6k in some parts of Europe, in particular Britain and Ireland. Furthermore, the relationship between summer-green and evergreen trees, and between individual tree taxa, differs significantly when expressed as pollen percentages or as REVEALS estimates of tree cover. For instance, when Pinus is dominant over Picea as pollen percentages, Picea is dominant over Pinus as REVEALS estimates. These differences play a major role in the reconstruction of European landscapes and for the study of land cover-climate interactions, biodiversity and human resources.
Assuntos
Biodiversidade , Mudança Climática , Modelos Teóricos , Dispersão Vegetal , Europa (Continente) , PólenRESUMO
The Black Death (1347-1352 CE) is the most renowned pandemic in human history, believed by many to have killed half of Europe's population. However, despite advances in ancient DNA research that conclusively identified the pandemic's causative agent (bacterium Yersinia pestis), our knowledge of the Black Death remains limited, based primarily on qualitative remarks in medieval written sources available for some areas of Western Europe. Here, we remedy this situation by applying a pioneering new approach, 'big data palaeoecology', which, starting from palynological data, evaluates the scale of the Black Death's mortality on a regional scale across Europe. We collected pollen data on landscape change from 261 radiocarbon-dated coring sites (lakes and wetlands) located across 19 modern-day European countries. We used two independent methods of analysis to evaluate whether the changes we see in the landscape at the time of the Black Death agree with the hypothesis that a large portion of the population, upwards of half, died within a few years in the 21 historical regions we studied. While we can confirm that the Black Death had a devastating impact in some regions, we found that it had negligible or no impact in others. These inter-regional differences in the Black Death's mortality across Europe demonstrate the significance of cultural, ecological, economic, societal and climatic factors that mediated the dissemination and impact of the disease. The complex interplay of these factors, along with the historical ecology of plague, should be a focus of future research on historical pandemics.
Assuntos
Peste , Yersinia pestis , Animais , DNA Antigo , Europa (Continente)/epidemiologia , Humanos , Pandemias/história , Peste/epidemiologia , Peste/história , Peste/microbiologia , Yersinia pestis/genéticaRESUMO
8000 years ago, prior to Neolithic agriculture, Europe was mostly a wooded continent. Since then, its forest cover has been progressively fragmented, so that today it covers less than half of Europe's land area, in many cases having been cleared to make way for fields and pasture-land. Establishing the origin of Europe's current, more open land-cover mosaic requires a long-term perspective, for which pollen analysis offers a key tool. In this study we utilise and compare three numerical approaches to transforming pollen data into past forest cover, drawing on >1000 14C-dated site records. All reconstructions highlight the different histories of the mixed temperate and the northern boreal forests, with the former declining progressively since ~6000 years ago, linked to forest clearance for agriculture in later prehistory (especially in northwest Europe) and early historic times (e.g. in north central Europe). In contrast, extensive human impact on the needle-leaf forests of northern Europe only becomes detectable in the last two millennia and has left a larger area of forest in place. Forest loss has been a dominant feature of Europe's landscape ecology in the second half of the current interglacial, with consequences for carbon cycling, ecosystem functioning and biodiversity.
Assuntos
Biodiversidade , Florestas , Dispersão Vegetal , Plantas/classificação , Densidade Demográfica , Europa (Continente) , Fósseis , Humanos , Pólen , Datação RadiométricaRESUMO
The written recall of printed stories by a sample (N = 16) of severely deaf children (mean age 13:3) was compared with that of a slow-reading hearing sample. The deaf children recalled as much, or more, of the story content. In general, however, their recall contained more distortions of the kind that indicates a break-down of the temporal structure of the story. The writing of one story in Sign word order proved to have a facilitatory effect on close recall by the deaf children, but not upon their free recall (as measured by either the amount recalled or the number of distortions), thus clarifying a well-confirmed finding in the literature. The deaf had even more difficulty than the slow-hearing in employing a "top-down", schema-driven strategy at the whole passage level.
Assuntos
Surdez/psicologia , Memória , Rememoração Mental , Leitura , Redação , Adolescente , Atenção , Criança , Feminino , Humanos , Masculino , Língua de SinaisRESUMO
It is, in general, difficult to study cognitive structures in deaf children: in particular, the enquiry into the nature of their story-knowledge structures (or story schemata) is fraught with thorny methodological problems. While some of the available evidence would suggest that typical deaf children do not read "story schematically", theirs may be a problem of lack of access to (rather than absence of) such cognitive structures. On the other hand, it cannot be assumed a priori that cognitive structures are identical in deaf and hearing children. A study using a picture arrangement method is described, the results of which support the view that the story schemata of deaf children are basically similar to those of hearing children. Deaf children, however, may not utilise the presence of certain story features which, if presented to hearing children, lend strength and salience to the story line.
Assuntos
Formação de Conceito , Surdez/psicologia , Educação Inclusiva , Rememoração Mental , Leitura , Aprendizagem Verbal , Atenção , Criança , Surdez/reabilitação , Feminino , Humanos , MasculinoRESUMO
A microbiological survey was conducted to determine the levels of total and pathogenic Vibrio parahaemolyticus (Vp) and Vibrio vulnificus (Vv) in Pacific oysters (Crassostrea gigas) collected from commercial growing areas in the North Island, New Zealand. The survey was intended to be geographically representative of commercial growing areas of Pacific oysters in New Zealand, while selecting the time frame most likely to coincide with the increased abundance of pathogenic vibrio species. Vp was detected in 94.8% of oyster samples examined (n=58) with a geometric mean concentration of 99.3 MPN/g, while Vv was detected in 17.2% of oyster samples examined with a geometric mean concentration of 7.4 MPN/g. The frequency of Vp positive samples was 1.7 fold greater than reported in a study conducted three decades ago in New Zealand. Potentially virulent (tdh positive) Vp was detected in two samples (3.4%, n=58) while no trh (another virulence marker) positive samples were detected. 16S rRNA genotype could be assigned only to 58.8% of Vv isolates (8:1:1 A:B:AB ratio, n=10). There was a good agreement [98.2% of Vp (n=280) and 94.4% of Vv (n=18) isolates] between molecular tests and cultivation based techniques used to identify Vibrio isolates and there was a significant (R(2)=0.95, P<0.001, n=18) linear relationship between the MPN estimates by real-time PCR and cultivation. There was no significant correlation between any of the environmental parameters tested and Vp or Vv concentrations.
Assuntos
Crassostrea/microbiologia , Frutos do Mar/microbiologia , Vibrio parahaemolyticus/isolamento & purificação , Vibrio vulnificus/isolamento & purificação , Animais , Contagem de Colônia Microbiana , Contaminação de Alimentos/análise , Nova Zelândia , Vibrio parahaemolyticus/genéticaRESUMO
A rapid stability indicating assay for the determination of prostaglandin E1 (PGE1) in pharmaceuticals was developed using High Pressure Liquid Chromatography (HPLC). A solution of 20 micrograms/ml PGE1 in 4% alcohol and 0.9% saline has an activation energy of 18,683 cal/mol and the predicted shelf-lives were: at 4 degrees C t95 = 51.8 days and t90 = 106.5 days and at 25 degrees C t95 = 4.8 days and t90 = 9.8 days.