132,031 research outputs found

    Influence of microscopic transport coefficients on the formation probabilities for super-heavy elements

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    The formation probability is shown to increase by a few orders of magnitude if microscopic transport coefficients are used rather than those of the common macroscopic pictures. Quantum effects in collective dynamics are taken into account through the fluctuating force, as exhibited in diffusion coefficients for a Gaussian process. In the range of temperatures considered here, they turn out to be of lesser importance.Comment: 20 pages, 9 figures, replaced by revised version accepted for publication in NP

    Influence of solar ultraviolet-B radiation in New Zealand on white clover (Trifolium repens L.), ryegrass (Lolium perenne L.) and pea (Pisum sativum L.) : a thesis presented in partial fulfilment of the requirements for the degree of Master of Science in Agricultural Science at Massey University, Palmerston North, New Zealand

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    New Zealand pasture plants have been exposed to increasing levels of ultraviolet-B radiation (UV-B) as a result of stratospheric ozone depletion during recent years. Thus far, there has been only limited published information on UV-B effects on pasture plants growing under field conditions. This study set out to investigate effects of natural solar UV-B radiation in the field for the pasture species white clover (Trifolium repens L.) and ryegrass (Lolium perenne L.) and compared those with pea (Pisum sativum L.), another economically important crop. Contrasting UV-B levels were created with two filter systems, using UV-B-absorbing glasshouse polythene film and UV-B-transmitting perspex glass. A further treatment included open plots that were not covered by filters. Ambient UV-B irradiance levels were recorded daily during the experimental period in summer from early December 1995 to late February 1996. The pasture species were investigated in monoculture as well as in their typical association in an established sward that was regularly grazed by sheep. Morphological measurements included leaf expansion, leaf initiation, leaf senescence, stem elongation, above-ground biomass and aspects of plant reproduction. To identify possible responses related to UV-B protection, measurements included specific leaf mass (SLM), accumulation of UV-absoibing compounds and of anthocyanins. The highest UV-B levels occurred during the early- and midsummer period from mid December to late January. Clouding reduced UV-B irradiance by more than 70%. The UV-B-absorbing treatment reduced ambient UV-B levels by about 90%, and the transmitting filters by about 25%. Results from the monoculture trials revealed interspecific differences in UV-B sensitivity between the three plant species tested. Ryegrass and white clover appeared UV-B-sensitive in a number of vegetative morphological aspects, while pea generally displayed UV-B tolerance. Most features of UV-B sensitivity in the two pasture species were recorded during midsummer in January, with young plant pans particularly affected by the UV-B-transmitting treatments. The area of young white clover leaves was reduced by about 20%, and the length of young internodes by more than 25%. Solar UV-B increased the number of senescing ryegrass leaves in January and induced white clover inflorescence formation in February. Inflorescence numbers were also increased in pea under UV-B-transmitting filters. While there was no clear relationship between SLM and UV-B susceptibility, the biochemical studies suggest that the interspecific differences in UV-B sensitivity may be due to differences in the accumulation of UV-absorbing compounds and of anthocyanins. Average levels of UV-absorbing compounds across treatments were about 50% higher in pea than in the two pasture species. Furthermore and in contrast to the pasture species, pea showed the highest levels of anthocyanins under solar UV-B in January. The results from the sward trials were in general agreement with the findings from the monoculture studies, showing that morphological sensitivity under the UV-B-transmitting treatments could also be detected for white clover and ryegrass when grown in association. This was reflected in a reduction of white clover leaf area and of leaf elongation in mature ryegrass tillers by 13%, and by more than 20% in young ryegrass tillers. The effects on the two species under pasture conditions were also reflected in whole sward measurements, showing decreases in sward height of about 15% and in herbage accumulation of about 20% under UV-B-transmitting filters. In conclusion, the findings from this study show that near-ambient solar UV-B levels can affect the morphology of the two most commonly sown pasture plant species in New Zealand. In contrast, pea showed tolerance to UV-B and this may at least be partly due to higher intrinsic levels of UV-absorbing compounds

    SU(2) and SU(3) Yang-Mills thermodynamics and some implications

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    We sketch the development of effective theories for SU(2) and SU(3) Yang-Mills thermodynamics. The most important results are quoted and some implications for particle physics and cosmology are discussed.Comment: 18 pages, 5 figures, v3: consequences of a change in the evolution equations for the effective couplings implemented, practically no change in the physics, erratum to appear in the journal-published versio

    Fundamental and effective SU(2) Yang-Mills vertices

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    Calorons and plane waves within and in between them {\sl collectively} give rise to a thermal ground state. The latter provides a homgeneous energy density and a negative pressure, and it induces quasiparticle masses to part of the propagating spectrum of deconfining SU(2) Yang-Mills thermodynamics (dynamical gauge-symmetry breaking). In the present talk we discuss the role of a {\sl single} caloron in inducing effective local vertices, characterized by powers of \hbar, mediating the interaction of plane waves which propagate over large distances. The constraints on momentum transfers through effective 4-vertices are revisited.Comment: 4 pages, no figur

    The enriched Vietoris monad on representable spaces

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    Employing a formal analogy between ordered sets and topological spaces, over the past years we have investigated a notion of cocompleteness for topological, approach and other kind of spaces. In this new context, the down-set monad becomes the filter monad, cocomplete ordered set translates to continuous lattice, distributivity means disconnectedness, and so on. Curiously, the dual(?) notion of completeness does not behave as the mirror image of the one of cocompleteness; and in this paper we have a closer look at complete spaces. In particular, we construct the "up-set monad" on representable spaces (in the sense of L. Nachbin for topological spaces, respectively C. Hermida for multicategories); we show that this monad is of Kock-Z\"oberlein type; we introduce and study a notion of weighted limit similar to the classical notion for enriched categories; and we describe the Kleisli category of our "up-set monad". We emphasize that these generic categorical notions and results can be indeed connected to more "classical" topology: for topological spaces, the "up-set monad" becomes the upper Vietoris monad, and the statement "XX is totally cocomplete if and only if XopX^\mathrm{op} is totally complete" specialises to O. Wyler's characterisation of the algebras of the Vietoris monad on compact Hausdorff spaces.Comment: One error in Example 1.9 is corrected; Section 4 works now without the assuming core-compactnes

    SU(2,CMB), the nature of light and acceleratedcosmological expansion

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    We present quantitative and qualitative arguments in favor of the claim that, within the present cosmological epoch, the U(1)gamma factor in the Standard Model is an effective manifestation of SU(2) pure gauge dynamics of Yang-Mills scale Lambda ~ 10^-4 eV. Results for the pressure and the energy density in the deconfining phase of this theory, obtained in a nonperturbative and analytical way, support this connection in view of large-angle features inherent in the map of the CMB temperature fluctuations and temperature-polarization cross correlations

    Interpretation Rules and Good Faith as Obstacles to the UK\u27s Ratification of the CISG and to the Harmonization of Contract Law in Europe

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    This essay examines Article 7 of the CISG, the provision on the Convention’s interpretation, through the lenses of both German and English law in order to shed light on interpretative issues in which there are divergent views in common law and civil law systems. The essay further provides possible reasons for the non-ratification of the CISG by the UK in contrast to its broad acceptance in Germany. The author more closely examines the issue of good faith as a principle of contract law, its vagueness being one of the possible reasons for the reluctance to ratify the CISG in England. The essay will conclude with an outlook on current and future efforts to harmonize contract law in Europe, notably with regards to the new (Draft) Common Frame of Reference. The question raised is whether the Common Frame of Reference has a chance of being accepted by the European civil law countries as well as by England and Wales as common law jurisdictions

    SU(2) Quantum Yang-Mills Thermodynamics: Some Theory and Some Applications

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    In the first part of this talk we review some prerequisites for and essential arguments involved in the construction of the thermal-ground-state estimate for the deconfining phase in the thermodynamics of SU(2) Quantum Yang-Mills theory and how this structure supports its distinct excitations. The second part applies deconfining SU(2) Yang-Mills thermodynamics to the Cosmic Microwave Background in view of (i) a modified temperature-redshift relation with an interesting link to correlation-length criticality in the 3D Ising model, (ii) the implied minimal changes in the dark sector of the cosmological model, and (iii) best-fit parameter values of this model when confronted with the spectra of the angular two-point functions TT, TE, and EE, excluding the low-ll physics. The latter, which is treated in an incomplete way because of the omission of radiative effects, is addressed in passing towards future work.Comment: 14 pp, 3 figs, v2: slightly extended text, removal of typo
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