1,474 research outputs found
Effects on herbicides on hedgerow biodiversity
Low dosages of herbicides may reduce the number of flowers on non-target plants. Effect of herbicides on flowering and on pollen and nectar production are relevant end-points for effect assessment on non-target species. Herbicides have the potential to reduce the number of flowers in hedgerow vegetation and thereby also decrease the availability of pollen, nectar and seeds that are important food for many insects and birds. The biodiversity of hedgerow bottom vegetation is lower at conventional than at organic farms, presumably as a consequence of the herbicide use
Bond percolation of polymers
We study bond percolation of non-interacting Gaussian polymers of
segments on a 2D square lattice of size with reflecting boundaries. Through
simulations, we find the fraction of configurations displaying {\em no}
connected cluster which span from one edge to the opposite edge. From this
fraction, we define a critical segment density and the
associated critical fraction of occupied bonds , so that they
can be identified as the percolation threshold in the limit.
Whereas is found to decrease monotonically with for a
wide range of polymer lengths, is non-monotonic. We give
physical arguments for this intriguing behavior in terms of the competing
effects of multiple bond occupancies and polymerization.Comment: 4 pages with 6 figure
Frequency dependent deformation of liquid crystal droplets in an external electric field
Nematic drops suspended in the isotropic phase of the same substance were
subjected to alternating electrical fields of varying frequency. The system was
carefully kept in the isotropic-nematic coexistance region, which was broadened
due to small amounts of non-mesogenic additives. Whereas the droplets remained
spherical at low (order of 10 Hz) and high frequencies (in the kHz range), at
intermediate frequencies, we observed a marked flattening of the droplet in the
plane perpendicular to the applied field. The deformation of the liquid crystal
(LC) droplets occurred both in substances with positive and negative dielectric
anisotropy. The experimental data can be quantitatively modelled with a
combination of the leaky dielectric model and screening of the applied electric
field due to the finite conductivity.Comment: minor change
Π’ΡΠ°Π½ΡΠΊΡΠΈΠΎΠ½Π½ΡΠ΅ ΠΈΠ·Π΄Π΅ΡΠΆΠΊΠΈ: ΠΎΠΏΠΏΠΎΡΡΡΠ½ΠΈΡΡΠΈΡΠ΅ΡΠΊΠΎΠ΅ ΠΏΠΎΠ²Π΅Π΄Π΅Π½ΠΈΠ΅
Metabolomic profiles are gender, disease and time specific in the interleukin-10 gene-deficient mouse model of inflammatory bowel disease.
Metabolomic profiling can be used to study disease-induced changes in inflammatory bowel diseases (IBD). The aim of this study was to investigate the difference in the metabolomic profile of males and females as they developed IBD. Using the IL-10 gene-deficient mouse model of IBD and wild-type mice, urine at age 4, 6, 8, 12, 16, and 20 weeks was collected and analyzed by nuclear magnetic resonance (NMR) spectroscopy. Multivariate data analysis was employed to assess differences in metabolomic profiles that occurred as a consequence of IBD development and severity (at week 20). These changes were contrasted to those that occurred as a consequence of gender. Our results demonstrate that both IL-10 gene-deficient and wild-type mice exhibit gender-related changes in urinary metabolomic profile over time. Some male-female separating metabolites are common to both IL-10 gene-deficient and control wild-type mice and, therefore, appear to be related predominantly to gender maturation. In addition, we were able to identify gender-separating metabolites that are unique for IL-10 gene-deficient and wild-type mice and, therefore, may be indicative of a gender-specific involvement in the development and severity of the intestinal inflammation. The comparison of the gender-separating metabolomic profile from IL-10 gene-deficient mice and wild-type mice during the development of IBD allowed us to identify changes in profile patterns that appear to be imperative in the development of intestinal inflammation, but yet central to gender-related differences in IBD development. The knowledge of metabolomic profile differences by gender and by disease severity has potential clinical implications in the design of both biomarkers of disease as well as the development of optimal therapies
Predict the distribution of nanoparticles in molten metal
In the present study the results of mathematical modeling of the process of introducing particles into an aluminum melt using the mixing device. A pattern of the distribution of these particles in the melt is obtained
The convergence of the ab-initio many-body expansion for the cohesive energy of solid mercury
A many-body expansion for mercury clusters of the form E = \sum_{i<j}\Delta
\epsilon_{ij} + \sum_{i<j<k}\Delta \epsilon_{ijk} + ... \quad, does not
converge smoothly with increasing cluster size towards the solid state. Even
for smaller cluster sizes (up to n=6), where van der Waals forces still
dominate, one observes bad convergence behaviour. For solid mercury the
convergence of the many-body expansion can dramatically be improved by an
incremental procedure within an embedded cluster approach. Here one adds the
coupled cluster many-body electron correlation contributions of the embedded
cluster to the bulk HF energy. In this way we obtain a cohesive energy (not
corrected for zero-point vibration) of 0.79 eV in perfect agreement with the
experimental value.Comment: 10 pages, 3 figures, accepted PR
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