44,284 research outputs found
Influence of diesel fuel on seed germination
The use of plant-based systems to remediate contaminated soils has become an area of intense scientific study in recent years and it is apparent that plants which grow well in contaminated soils need to be identified and screened for use in phytoremediation technologies. This study investigated the effect of diesel fuel on germination of selected plant species. Germination response varied greatly with plant species and was species specific, as members of the same plant family showed differential sensitivity to diesel fuel contamination. Differences were also seen within plant subspecies. At relatively low levels of diesel fuel contamination, delayed seed emergence and reduced percentage germination was observed for the majority of plant species investigated. Results suggest the volatile fraction of diesel fuel played an influential role in delaying seed emergence and reducing percentage germination. In addition, the remaining diesel fuel in the soil Lidded to this inhibitory effect on germination by physically impeding water and oxygen transfer between the seed and the surrounding soil environment, thus hindering the germination response
Linear-in-mass-ratio contribution to spin precession and tidal invariants in Schwarzschild spacetime at very high post-Newtonian order
Using black hole perturbation theory and arbitrary-precision computer
algebra, we obtain the post-Newtonian (pN) expansions of the
linear-in-mass-ratio corrections to the spin-precession angle and tidal
invariants for a particle in circular orbit around a Schwarzschild black hole.
We extract coefficients up to 20pN order from numerical results that are
calculated with an accuracy greater than 1 part in . These results
can be used to calibrate parameters in effective-one-body models of compact
binaries, specifically the spin-orbit part of the effective Hamiltonian and the
dynamically significant tidal part of the main radial potential of the
effective metric. Our calculations are performed in a radiation gauge, which is
known to be singular away from the particle. To overcome this irregularity, we
define suitable Detweiler-Whiting singular and regular fields in this gauge,
and we devise a rigorous mode-sum regularization method to compute the
invariants constructed from the regular field
Deformations of spacetime and internal symmetries
Algebraic deformations provide a systematic approach to generalizing the
symmetries of a physical theory through the introduction of new fundamental
constants. The applications of deformations of Lie algebras and Hopf algebras
to both spacetime and internal symmetries are discussed. As a specific example
we demonstrate how deforming the classical flavor group to the quantum
group (a Hopf algebra) and taking into account
electromagnetic mass splitting within isospin multiplets leads to new and
exceptionally accurate baryon mass sum rules that agree perfectly with
experimental data.Comment: 5th International Conference on New Frontiers in Physics, Crete,
Greece, July 6-14, 201
Quantum stochastic convolution cocycles II
Schuermann's theory of quantum Levy processes, and more generally the theory
of quantum stochastic convolution cocycles, is extended to the topological
context of compact quantum groups and operator space coalgebras. Quantum
stochastic convolution cocycles on a C*-hyperbialgebra, which are
Markov-regular, completely positive and contractive, are shown to satisfy
coalgebraic quantum stochastic differential equations with completely bounded
coefficients, and the structure of their stochastic generators is obtained.
Automatic complete boundedness of a class of derivations is established,
leading to a characterisation of the stochastic generators of *-homomorphic
convolution cocycles on a C*-bialgebra. Two tentative definitions of quantum
Levy process on a compact quantum group are given and, with respect to both of
these, it is shown that an equivalent process on Fock space may be
reconstructed from the generator of the quantum Levy process. In the examples
presented, connection to the algebraic theory is emphasised by a focus on full
compact quantum groups.Comment: 32 pages, expanded introduction and updated references. The revised
version will appear in Communications in Mathematical Physic
Influence of dietary linoleic acid intake with different fat intakes on arachidonic acid concentrations in plasma and platelet lipids and eicosanoid biosynthesis in female volunteers
Background/Aim: N-6 fatty acids are considered to promote diseases prevalent in industrialized countries and characterized by an increased eicosanoid biosynthesis from arachidonic acid (AA). We investigated the impact of the linoleic acid (LA) intake on AA levels in humans. Methods: Six healthy female volunteers (age range 2334 years) were given liquid formula diets (LFD) devoid of AA for 6 weeks, providing a constant intake of zero energy% (LFD 0: protein 15%, carbohydrates 85%) or 20 energy% (LFD 20: protein 15%, carbohydrates 55%, fat 30%) LA, for 3 weeks each. Fatty acids of plasma cholesteryl esters and platelet lipids were determined each week, and the prostaglandin biosynthesis was measured in 24-hour urine samples. Results: LFD 0 increased (+31% of initial value) and LFD 20 lowered (-30% of initial value) the percentage of AA in plasma cholesteryl esters and platelet lipids. Moreover, absence of dietary AA lowered the percentages of AA in plasma (-31% week 0 vs. week 6) and platelet (-11%) lipids, indicating a low transformation of LA. LFD 0 reduced urinary metabolite levels of prostaglandins D, E, and F in 24-hour urine samples (-48%, p < 0.001) within 24 h, but did not significantly affect platelet aggregation (-10%) and thromboxane formation (-25%). LFD 20 significantly lowered platelet aggregation (-25%) and thromboxane formation (-43%). The prostaglandin metabolite levels increased during the first 10 days, declined thereafter, and were lower than the preexperimental values at the end of the 3-week period. Conclusions: The results show that dietary LA does not increase the AA levels in plasma or platelet lipids and does not persistently contribute to prostaglandin biosynthesis which is increased by AA intake with Western diets
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