10,374 research outputs found
A new microscopic nucleon-nucleon interaction derived from relativistic mean field theory
A new microscopic nucleon-nucleon (NN) interaction has been derived for the
first time from the popular relativistic mean field theory (RMFT) Lagrangian.
The NN interaction so obtained remarkably relate to the inbuilt fundamental
parameters of RMFT. Furthermore, by folding it with the RMFT-densities of
cluster and daughter nuclei to obtain the optical potential, it's application
is also examined to study the exotic cluster radioactive decays, and results
obtained found comparable with the successfully used M3Y phenomenological
effective NN interactions. The presently derived NN-interaction can also be
used to calculate a number of other nuclear observables.Comment: 4 Pages 2 Figure
Modification of kraft wood-pulp fibre with silica for surface functionalisation
A new science strategy for natural fibre modification was devised in which glass surface properties would be imparted to wood-derived fibre. The enhancements known from addition of silane reagents to glass fibre–polymer composites could therefore be realised for modified cellulose fibre–polymer composites. A process is described whereby the internal void spaces and micropores of never-dried Kraft pulp fibre walls were impregnated with silica. This was achieved by initial dehydration of never-dried fibre through azeotropic distillation to achieve substitution of fibre water with the silicon chemical solution over a range of concentrations. Kraft fibres were stiffened and made resistant to collapse from the effect of the azeotrope drying. Specific chemical reaction of azeotrope-dried fibre with the reagent ClSi(OEt)3 followed by base-catalysed hydrolysis of the ester groups formed a fibre-bound silica composite. The physico-chemical substitution of water from micropores and internal voids of never-dried fibre with property-modifying chemicals offers possibilities in the development of new fibre characteristics, including fibres which may be hardened, plasticised, and/or stabilised against moisture, biodegradation or fire. The embedded silica may also be used as sites of attachment for coupling agents to modify the hydrophilic character of the fibre or to functionalise the fibre surface
Ediacara biota flourished in oligotrophic and bacterially dominated marine environments across Baltica.
Middle-to-late Ediacaran (575-541 Ma) marine sedimentary rocks record the first appearance of macroscopic, multicellular body fossils, yet little is known about the environments and food sources that sustained this enigmatic fauna. Here, we perform a lipid biomarker and stable isotope (δ15Ntotal and δ13CTOC) investigation of exceptionally immature late Ediacaran strata (<560 Ma) from multiple locations across Baltica. Our results show that the biomarker assemblages encompass an exceptionally wide range of hopane/sterane ratios (1.6-119), which is a broad measure of bacterial/eukaryotic source organism inputs. These include some unusually high hopane/sterane ratios (22-119), particularly during the peak in diversity and abundance of the Ediacara biota. A high contribution of bacteria to the overall low productivity may have bolstered a microbial loop, locally sustaining dissolved organic matter as an important organic nutrient. These oligotrophic, shallow-marine conditions extended over hundreds of kilometers across Baltica and persisted for more than 10 million years
Thermally assisted adiabatic quantum computation
We study the effect of a thermal environment on adiabatic quantum computation
using the Bloch-Redfield formalism. We show that in certain cases the
environment can enhance the performance in two different ways: (i) by
introducing a time scale for thermal mixing near the anticrossing that is
smaller than the adiabatic time scale, and (ii) by relaxation after the
anticrossing. The former can enhance the scaling of computation when the
environment is superohmic, while the latter can only provide a prefactor
enhancement. We apply our method to the case of adiabatic Grover search and
show that performance better than classical is possible with a superohmic
environment, with no a priori knowledge of the energy spectrum.Comment: 4 pages, 2 figures, Final version to appear in PR
Space shuttle abort separation pressure investigation. Volume 2, Part B: Orbiter data at Mach 5
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Coherent laminar and turbulent motion of toroidal vortex bundles
Motivated by experiments performed in superfluid helium, we study numerically
the motion of toroidal bundles of vortex filaments in an inviscid fluid. We
find that the evolution of these large-scale vortex structures involves the
generalised leapfrogging of the constituent vortex rings. Despite three
dimensional perturbations in the form of Kelvin waves and vortex reconnections,
toroidal vortex bundles retain their coherence over a relatively large distance
(compared to their size), in agreement with experimental observations.Comment: 22 pages, 12 figure
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