10,435 research outputs found
A linear moose model with pairs of degenerate gauge boson triplets
The possibility of the existence of a strongly interacting electroweak
symmetry breaking sector, as opposed to the weakly interacting light Higgs of
the Standard Model, is not yet ruled out by experiments. In this paper we make
an extensive study of a deconstructed model (or ``moose'' model) providing a
possible effective description of such a strong symmetry breaking sector, and
show its compatibility with experimental data for a wide portion of the model
parameters space. The model is a direct generalization of the previously
proposed D-BESS model.Comment: Latex file, 17 pages, 2 figures, published versio
Analysis of Narrow s-channel Resonances at Lepton Colliders
The procedures for studying a single narrow s-channel resonance or nearly
degenerate resonances at a lepton collider, especially a muon collider, are
discussed. In particular, we examine four methods for determining the
parameters of a narrow s-channel resonance: scanning the resonance, measuring
the convoluted cross section, measuring the Breit-Wigner area, and sitting on
the resonance while varying the beam energy resolution. This latter procedure
is new and appears to be potentially very powerful. Our focus is on computing
the errors in resonance parameters resulting from uncertainty in the beam
energy spread. Means for minimizing these errors are discussed. The discussion
is applied to the examples of a light SM-Higgs, of the lightest pseudogoldstone
boson of strong electroweak breaking, and of the two spin-1 resonances of the
Degenerate BESS model (assuming that the beam energy spread is less than their
mass splitting). We also examine the most effective procedures for nearly
degenerate resonances, and apply these to the case of Degenerate BESS
resonances with mass splitting of order the beam energy spread.Comment: 63 pages, 16 figure
Nitrification-denitrification in WSP: a mechanism for permanent nitrogen removal in maturation ponds
A pilot-scale primary maturation pond was spiked with 15N-labelled ammonia (15NH4Cl) and 15N labelled nitrite (Na15NO2), in order to improve current understanding of the dynamics of inorganic nitrogen transformations and removal in WSP systems. Stable isotope analysis of δ15N showed that
nitrification could be considered as an intermediate step in WSP, which is masked by simultaneous denitrification, under conditions of low algal activity. Molecular microbiology analysis showed that denitrification can be considered a feasible mechanism for permanent nitrogen removal in WSP, which may be supported either by ammonia-oxidising bacteria (AOB) or by methanotrophs, in addition to nitrite-oxidising bacteria (NOB). However, the relative supremacy of the denitrification process over other nitrogen removal mechanisms (e.g., biological uptake) depends upon phytoplanktonic activity
A Strong Electroweak Sector at Future mu^+ mu^- Colliders
We discuss the prospects for detecting at a muon collider the massive new
vector resonances V and light pseudo-Nambu-Goldstone bosons P of a typical
strongly interacting electroweak sector (as represented by the BESS model).
Expected sensitivities to V's at a high energy collider are evaluated and the
excellent prospects for discovering P's via scanning at a low energy collider
are delineated.Comment: LaTeX, uses aipproc.cls, aipproc.sty, 10 pages, 6 figures, presented
at the Workshop on Physics at the First Muon Collider, Fermilab, November
1997, to appear in the Proceedings, some references added and minor changes
in the tex
Economies of Size for Conventional Tillage and No-till Wheat Production
Production costs and economies of size for both conventional tillage and no-till wheat production were determined. The reduction in the price of glyphosate after the patent expired improved the relative economics of no-till for continuous monoculture winter wheat. Production costs differ across farm size and by production system.Crop Production/Industries,
Comparison of artificial neural network analysis with other multimarker methods for detecting genetic association
<p>Abstract</p> <p>Background</p> <p>Debate remains as to the optimal method for utilising genotype data obtained from multiple markers in case-control association studies. I and colleagues have previously described a method of association analysis using artificial neural networks (ANNs), whose performance compared favourably to single-marker methods. Here, the perfomance of ANN analysis is compared with other multi-marker methods, comprising different haplotype-based analyses and locus-based analyses.</p> <p>Results</p> <p>Of several methods studied and applied to simulated SNP datasets, heterogeneity testing of estimated haplotype frequencies using asymptotic <it>p </it>values rather than permutation testing had the lowest power of the methods studied and ANN analysis had the highest power. The difference in power to detect association between these two methods was statistically significant (<it>p </it>= 0.001) but other comparisons between methods were not significant. The raw <it>t </it>statistic obtained from ANN analysis correlated highly with the empirical statistical significance obtained from permutation testing of the ANN results and with the <it>p </it>value obtained from the heterogeneity test.</p> <p>Conclusion</p> <p>Although ANN analysis was more powerful than the standard haplotype-based test it is unlikely to be taken up widely. The permutation testing necessary to obtain a valid <it>p </it>value makes it slow to perform and it is not underpinned by a theoretical model relating marker genotypes to disease phenotype. Nevertheless, the superior performance of this method does imply that the widely-used haplotype-based methods for detecting association with multiple markers are not optimal and efforts could be made to improve upon them. The fact that the <it>t </it>statistic obtained from ANN analysis is highly correlated with the statistical significance does suggest a possibility to use ANN analysis in situations where large numbers of markers have been genotyped, since the <it>t</it> value could be used as a proxy for the <it>p </it>value in preliminary analyses.</p
The Lightest Pseudo-Goldstone Boson at Future e+e- Colliders
In a class of models of dynamical symmetry breaking not ruled out by the
available data, the lightest neutral pseudo-Nambu-Goldstone boson P0 contains
only down-type techniquarks and charged technileptons. Its mass scale is
naturally determined by the b-quark and therefore it is likely to be light. As
the presence of pseudo-Nambu-Goldstone bosons in models of dynamical symmetry
breaking is a quite general feature, the search of the P0 at colliders is an
interesting opportunity of putting limits on or discovering a dynamical
electroweak symmetry breaking scenario. In this note we discuss the prospects
for discovering and studying the P0 at future e+e- and gamma-gamma colliders.Comment: 15 pages, 8 figures, LaTeX (epsfig), Proceedings of the Second
ECFA/DESY Study on Physics Studies for a Future Linear Collide
Photometric and spectroscopic gamma-ray observations of solar transient phenomena using long duration balloons
A program currently in progress to conduct extended duration spectroscopic and photometric observation of solar X-ray phenomena from balloons is described. High photometric sensitivity to weak hard X-ray bursts is attained using a 600 sq cm array of phoswich scintillators. High spectral resolution for stronger bursts is available from an array of planar germanium detectors. These instruments are carried in a novel balloon gondola dssigned for the 15 to 20 day float durations available through using conventional zero pressure balloons in the radiation controlled (RACOON) mode
- …