1,440 research outputs found
Relations between topography, wetlands, vegetation cover and stream water chemistry in boreal headwater catchments in Sweden
International audienceA large part of the spatial variation of stream water chemistry is found in headwater streams and small catchments. To understand the dominant processes, taking place in small and heterogeneous catchments, spatial and temporal data with high resolution is needed. In most cases available map data has too low quality and resolution to successfully be used in environmental assessments and modelling. In this study 18 forested catchments (1?4 km2) were selected within a 120×50 km area in the county of Värmland in western Sweden. The aim was to test if topographic and vegetation variables derived from official datasets were correlated to stream water chemistry, represented by DOC, Al, Fe and Si content. A GIS was used to analyse the elevation characteristics, generate topographic indices and calculate the percentage of wetlands and a number of vegetation classes. The results clearly show that the topography has a major influence on the occurrence of wetlands, which has a major influence on stream water chemistry. There were very strong correlations between mean slope and percentage wetland, percentage wetland and DOC, mean slope and DOC and mean topographic wetness index and DOC. The conclusion was that official topographic data, despite uncertain or low quality and resolution, could be useful in the prediction of headwater chemistry in boreal forested catchments
Surveillance of Ruminant Diseases in the Nordic Countries
<p/> <p>All the Nordic countries have a basis for their surveillance and disease control in ruminants in national legislation and regulations listing notifiable diseases of concern to the countries. The Nordic countries are a disease-free zone comparing to other parts of the world and the aim of the surveillance is to keep that status and be able to document it. Following is a short summary from each country.</p
Market size, competition, and the product mix of exporters
We build a theoretical model of multi-product firms that highlights how market size and ge-
ography (the market sizes of and bilateral economic distances to trading partners) affect both a
firm's exported product range and its exported product mix across market destinations (the dis-
tribution of sales across products for a given product range). We show how tougher competition
in an export market induces a firm to skew its export sales towards its best performing products.
We find very strong confirmation of this competitive effect for French exporters across export
market destinations. Trade models based on exogenous markups cannot explain this strong sig-
nificant link between destination market characteristics and the within-firm skewness of export
sales (after controlling for bilateral trade costs). Theoretically, this within firm change in prod-
uct mix driven by the trading environment has important repercussions on firm productivity
and how it responds to changes in that trading environment
A combined tactile and Raman probe for tissue characterization - Design considerations
Histopathology is the golden standard for cancer diagnosis and involves the characterization of tissue components. It is labour intensive and time consuming. We have earlier proposed a combined fibre-optic near-infrared Raman spectroscopy (NIR-RS) and tactile resonance method (TRM) probe for detecting positive surgical margins as a complement to interoperative histopathology. The aims of this study were to investigate the effects of attaching an RS probe inside a cylindrical TRM sensor and to investigate how laser-induced heating of the fibre-optic NIR-RS affected the temperature of the RS probe tip and an encasing TRM sensor. In addition, the possibility to perform fibre-optic NIR-RS in a well-lit environment was investigated. A small amount of rubber latex was preferable for attaching the thin RS probe inside the TRM sensor. The temperature rise of the TRM sensor due to a fibre-optic NIR-RS at 270 mW during 20 s was less than 2 degrees C. Fibre-optic NIR-RS was feasible in a dimmed bright environment using a small light shield and automatic subtraction of a pre-recorded contaminant spectrum. The results are promising for a combined probe for tissue characterization
Extension of nano-confined DNA: quantitative comparison between experiment and theory
The extension of DNA confined to nanochannels has been studied intensively
and in detail. Yet quantitative comparisons between experiments and model
calculations are difficult because most theoretical predictions involve
undetermined prefactors, and because the model parameters (contour length, Kuhn
length, effective width) are difficult to compute reliably, leading to
substantial uncertainties. Here we use a recent asymptotically exact theory for
the DNA extension in the "extended de Gennes regime" that allows us to compare
experimental results with theory. For this purpose we performed new
experiments, measuring the mean DNA extension and its standard deviation while
varying the channel geometry, dye intercalation ratio, and ionic buffer
strength. The experimental results agree very well with theory at high ionic
strengths, indicating that the model parameters are reliable. At low ionic
strengths the agreement is less good. We discuss possible reasons. Our approach
allows, in principle, to measure the Kuhn length and effective width of a
single DNA molecule and more generally of semiflexible polymers in solution.Comment: Revised version, 6 pages, 2 figures, 1 table, supplementary materia
Description of the Infection Status in a Norwegian Cattle Herd Naturally Infected by Mycobacterium avium subsp. paratuberculosis
The Norwegian surveillance and control programme for paratuberculosis revealed 8 seroreactors in a single dairy cattle herd that had no clinical signs of Mycobacterium avium subsp. paratuberculosis (M. a. paratuberculosis) infection. Paratuberculosis had been a clinical problem in goats several years previously in this herd. All 45 cattle were culled and a thorough investigation of the infection status was conducted by the use of interferon-γ (IFN-γ) immunoassay, measurement of antibodies, and pathological and bacteriological examination
Phenomenon of Cloning and specificity of its usage
Cloning is studied by different branches of science. Medicine is interested in cloning because of its ability to transplant special tissues and organs, genetics - with the purpose of studying heredity and succession, sociology deals with moral and ethic aspects of the phenomenon. The paper is devoted to the study of cloning, its special features and usage in different spheres of social life. The article represents main types of cloning, specificity of vegetative and animal cloning and problems of its expansion. The paper also demonstrates the actual topic of nowadays studies connected with human cloning and its aftereffects for science and society. The article may be useful for a wide audience and for people, who are interested in studies of cloning and problems of its realization
Characterizing antibiotics in LCA-a review of current practices and proposed novel approaches for including resistance
Purpose With antibiotic resistance (ABR) portrayed as an increasing burden to human health, this study reviews how and to what extent toxicological impacts from antibiotic use are included in LCAs and supplement this with two novel approaches to include ABR, a consequence of antibiotic use, into the LCA framework. Methods We review available LCA studies that deal with toxicological aspects of antibiotics to evaluate how these impacts from antibiotics have been characterized. Then, we present two novel approaches for including ABR-related impacts in life cycle impact assessments (LCIAs). The first approach characterizes the potential for ABR enrichment in the environmental compartment as a mid-point indicator, based on minimum selective concentrations for pathogenic bacteria. The second approach attributes human health impacts as an endpoint indictor, using quantitative relationships between the use of antibiotics and human well-being. Results and discussion Our findings show that no LCA study to date have accounted for impacts related to ABR. In response, we show that our novel mid-point indicator approach could address this by allowing ABR impacts to be characterized for environmental compartments. We also establish cause-effect pathways between antibiotic use, ABR, and human well-being that generate results which are comparable with USEtox and most endpoint impact assessment approaches for human toxicology. Conclusions Our proposed methods show that currently overlooked impacts from ABR enrichment in the environment could be captured within the LCA framework as a robust characterization methodology built around the established impact model USEtox. Substantial amounts of currently unavailable data are, however, needed to calculate emissions of antibiotics into the environment, to develop minimum selective concentrations for non-pathogenic bacteria, and to quantify potential human health impacts from AB use.Industrial Ecolog
Nanoconfined circular and linear DNA - equilibrium conformations and unfolding kinetics
Studies of circular DNA confined to nanofluidic channels are relevant both
from a fundamental polymer-physics perspective and due to the importance of
circular DNA molecules in vivo. We here observe the unfolding of DNA from the
circular to linear configuration as a light-induced double strand break occurs,
characterize the dynamics, and compare the equilibrium conformational
statistics of linear and circular configurations. This is important because it
allows us to determine to which extent existing statistical theories describe
the extension of confined circular DNA. We find that the ratio of the
extensions of confined linear and circular DNA configurations increases as the
buffer concentration decreases. The experimental results fall between
theoretical predictions for the extended de Gennes regime at weaker confinement
and the Odijk regime at stronger confinement. We show that it is possible to
directly distinguish between circular and linear DNA molecules by measuring the
emission intensity from the DNA. Finally, we determine the rate of unfolding
and show that this rate is larger for more confined DNA, possibly reflecting
the corresponding larger difference in entropy between the circular and linear
configurations.Comment: 21 pages, 7 figures, 1 tabl
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