676 research outputs found
Small-scale Collembola community composition in a pine forest soil - Overdispersion in functional traits indicates the importance of species interactions
Soil communities are considered to be remarkably species-rich and to have many generalist species with seemingly similar niche requirements. The composition of soil fauna communities is often highly variable even at the plot scale, and both the environment and the spatial configuration of microhabitats are regarded as important forces shaping the structure of local communities. However, to what extent these forces are important in different ecosystems is not clear. We examined the relative roles of environmental (abiotic), vegetation (biotic) and spatial variables (using Moran's eigenvector maps, MEM) for the small-scale variation in springtail (Collembola) communities in a 100 m(2) area of the forest floor of a mature Scots pine forest in central Sweden, with small variation in important environmental variables.We found that most of the small-scale variation in community composition could be explained by spatial variables, either alone or jointly with the environmental variables. Spatial variability in community composition, in turn, could be related to shifts in functional traits of the component species. Within local communities (samples), species showed a higher diversity than expected by chance in almost all examined traits, indicating that differences in resource and micro-habitat utilisation enable Collembola species to coexist. Competition between species is therefore likely to be important for structuring Collembola communities at this spatial scale. The results indicate that the spatial scale of study and heterogeneity of environmental factors influence soil fauna community assembly processes through effects on the relative importance of environmental filtering compared to filtering by limiting similarity or competitive exclusion. (C) 2016 The Authors. Published by Elsevier Ltd
Barking up the wrong tree: Modern northern European dogs fail to explain their origin
<p>Abstract</p> <p>Background</p> <p>Geographic distribution of the genetic diversity in domestic animals, particularly mitochondrial DNA, has often been used to infer centers of domestication. The underlying presumption is that phylogeographic patterns among domesticates were established during, or shortly after the domestication. Human activities are assumed not to have altered the haplogroup frequencies to any great extent. We studied this hypothesis by analyzing 24 mtDNA sequences in ancient Scandinavian dogs. Breeds originating in northern Europe are characterized by having a high frequency of mtDNA sequences belonging to a haplogroup rare in other populations (HgD). This has been suggested to indicate a possible origin of the haplogroup (perhaps even a separate domestication) in central or northern Europe.</p> <p>Results</p> <p>The sequences observed in the ancient samples do not include the haplogroup indicative for northern European breeds (HgD). Instead, several of them correspond to haplogroups that are uncommon in the region today and that are supposed to have Asian origin.</p> <p>Conclusion</p> <p>We find no evidence for local domestication. We conclude that interpretation of the processes responsible for current domestic haplogroup frequencies should be carried out with caution if based only on contemporary data. They do not only tell their own story, but also that of humans.</p
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Interannual variation in global-scale net primary production: Testing model estimates
Testing estimates of yearâtoâyear variation in global net primary production (NPP) poses some challenges. Largeâscale, multiyear records of production are not readily available for natural systems but are for agricultural systems. We use records of agricultural yields at selected sites to test NPP estimates produced by CASA, a globalâscale production model driven by both meteorological data and the satelliteâderived normalized difference vegetation index (NDVI). We also test estimates produced by the Miami model, which has underlain several analyses of biosphere response to interannual changes in climate. In addition, we test estimates against tree ring data for one boreal site for which data from both coniferous and deciduous species were available. The agricultural tests demonstrate that CASA can reasonably estimate interannual variation in production. The Miami model estimates variation more poorly. However, differences in NDVIâprocessing algorithms substantially affect CASA's estimates of interannual variation. Of the four versions tested, the FASIR NDVI most closely reproduced yield data and showed the least correlation with changes in equatorial crossing time of the National Oceanic and Atmospheric Administration satellites. One issue raised is the source of the positive trends evident in CASA's NDVIâbased estimates of global NPP. The existence of these trends is consistent with potential stimulation of terrestrial production by factors such as CO2 enrichment, N fertilization, or temperature warming, but the magnitude of the global trends seen is significantly greater than suggested by constraints imposed by atmospheric fluxes
Predicting the effect of prandial stage and particle size on absorption of ODM-204.
The prediction of absorption properties plays a key role in formulation development when the compound under development shows poor solubility and its absorption is therefore presumed to be solubility limited. In our work, we combined and compared data obtained from in vitro dissolution tests, transit intestinal model studies (TIM -1) and physiologically based pharmacokinetic modelling. Our aim was to determine the ability of these methods to predict performance of poorly soluble lipophilic weak base in vivo. The validity of the predictive methods was evaluated against the in vivo clinical pharmacokinetic (PK) data obtained after administration of the first test formulation, Tl. The aim of our study was to utilize the models in evaluating absorption properties of the second test formulation, T2, which has not yet been clinically administered. The compound in the studies was ODM-204, which is a novel, orally administered, investigational, nonsteroidal dual inhibitor of CYP17A1 and androgen receptor. Owing to its physicochemical properties ODM-204 is prone to low or variable bioavailability. The models examined provided congruent data on dose dependent absorption, food effect at a dose of 200 mg and on the effect of API (active pharmaceutical ingredient) particle size on absorption. Our study shows that the predictive tools of in vitro dissolution, TIM-1 system and the PBPK (physiologically based pharmacokinetic) simulation, showed predictive power of different mechanisms of bioavailability and together provided valuable information for decision making.Peer reviewe
Swath-ms: a new data independent acquisition LC-MS methodology for quantitative complete proteome analysis
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Oral health indices predict individualised recall interval
Objectives: The individualised recall interval (IRI) is part of the oral health examination. This observational, register-based study aimed to explore how oral health indices DMFT (decayed, missing, filled teeth), DT (decayed teeth), CPI (Community Periodontal Index, maximum value of individual was used) and number of teeth are associated with IRI for adults. Methods: Oral health examination includes an assessment of all oral tissues, diagnosis, a treatment plan and assessment and a determination of the interval before the next assessment. It is called the IRI. This cross-sectional study population included 42,533 adults (age range 18-89 years), who had visited for an oral health examination during 2009, provided by the Helsinki City Social Services and Health Care. The recall interval was categorised into an ordinal scale (0-12, 13-24, 25-36 and 37-60 months) and was modelled using a proportional odds model. ORs less than one indicated a shorter recall interval. Results: Recall interval categories in the study population were 0-12 months (n = 4,569; 11%), 13-24 months (n = 23,732; 56%), 25-36 months (n = 12,049; 28%), and 37-60 months (n = 2,183; 5%). The results of statistical models clearly showed an association between the length of recall intervals and oral health indices. In all models, higher values of DMFT, DT and CPI indicated a shorter recall interval. The number of teeth were not so relevant. The association was not influenced when different combinations of other predictors (age, gender, socioeconomic status, chronic diseases) were included in the model. The severity of periodontitis predicted a short recall interval, for example, in the Model 1, CPI maximum value 4 was OR = 0.35 (95% confidence interval 0.31-0.40). Conclusions: The oral health indices showed a clear association with the length of the IRI. Poor oral health reduced IRI. The indices provide information about the amount of oral health prevention required and are useful to health organisations.Peer reviewe
Bias-voltage dependence of the magneto-resistance in ballistic vacuum tunneling: Theory and application to planar Co(0001) junctions
Motivated by first-principles results for jellium and by surface-barrier
shapes that are typically used in electron spectroscopies, the bias voltage in
ballistic vacuum tunneling is treated in a heuristic manner. The presented
approach leads in particular to a parameterization of the tunnel-barrier shape,
while retaining a first-principles description of the electrodes. The proposed
tunnel barriers are applied to Co(0001) planar tunnel junctions. Besides
discussing main aspects of the present scheme, we focus in particular on the
absence of the zero-bias anomaly in vacuum tunneling.Comment: 19 pages with 8 figure
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