4,327 research outputs found
Higgs boson searches at LEP
In this paper we report on the legacy of Higgs boson searches at LEP.
Specifically, the results of the statistical combination of the searches
carried out by the ALEPH, DELPHI, L3 and OPAL experiments are presented. In the
search for the Standard Model (SM) Higgs boson, a signal with mh<114.4 GeV/c^2
has been excluded at the 95% confidence level (CL) or higher. The LEP
collaborations also carried out extensive searches for Higgs particles
predicted by many scenarios beyond the Standard Model. Here we can only report
on a very small fraction of these searches and refer the reader to the complete
list of LEP-combined search results.Comment: 3 pages, 2 figures; submitted for proceedings of EPS HEP2007
Conference (19-25 July; Manchester, UK
Upper limit on mh in the MSSM and M-SUGRA vs. prospective reach of LEP
The upper limit on the lightest CP-even Higgs boson mass, mh, is analyzed
within the MSSM as a function of tan(beta) for fixed mtop and Msusy. The impact
of recent diagrammatic two-loop results on this limit is investigated. We
compare the MSSM theoretical upper bound on mh with the lower bound obtained
from experimental searches at LEP. We estimate that with the LEP data taken
until the end of 1999, the region mh < 108.2 GeV can be excluded at the 95%
confidence level. This corresponds to an excluded region 0.6 <= tan(beta) <=
1.9 within the MSSM for mtop = 174.3 GeV and Msusy <= 1 TeV. The final
exclusion sensitivity after the end of LEP, in the year 2000, is also briefly
discussed. Finally, we determine the upper limit on mh within the Minimal
Supergravity (M-SUGRA) scenario up to the two-loop level, consistent with
radiative electroweak symmetry breaking. We find an upper bound of mh \approx
127 GeV for mtop = 174.3 GeV in this scenario, which is slightly below the
bound in the unconstrained MSSM.Comment: 10 pages, 3 figure
Sensitivity of ATLAS to FCNC single top quark production
The anomalous production of single top quarks via flavour-changing neutral currents (FCNCs), u(c)+g -> t, is studied using the ATLAS detector at the Large Hadron Collider. Detector simulation is done using the fast simulation package ATLFAST. A number of important systematic effects have been addressed. Based on a cut-based analysis, we shows that, with 10 fb-1, ATLAS can observe such top FCNC interactions with 5 sigma significance if the anomalous coupling strengths are k_ug/Lambda=k_cg/Lambda >= 0.0120 (sys.) TeV-1, or equivalently Br(t->ug)+Br(t->cg) >= 2.64 (sys.) x 10^{-4}$. In terms of production cross section, such a discovery requires at least 13.7 pb of anomalous single top quark production. With this level of sensitivity, ATLAS will be able to test some models of new physics
Reforço de edifĂcios existentes de betĂŁo armado com contraventamentos metĂĄlicos
Foi calibrado um modelo numĂ©rico refinado para a reprodução do comportamento de estruturas existentes de betĂŁo armado, e do seu reforço por contraventamento, face a solicitaçÔes sĂsmicas. Estes modelos foram calibrados com base numa sĂ©rie de ensaios
Tortuosity variation in a low density binary particulate bed
The importance of particle size ratio and particle composition in the properties of a mixed bed is well known. Nevertheless, the dependence of the bed channel tortuosity T on the porosity Δ in the form T=1/Δn, where n is assumed to be a constant, shows that the value of n depends on the properties
of the packed bed. For loose packing, experimental data for binary mixtures of glass beads of a size ratio from 1 up to 53.8 was analysed in terms of porosity, tortuosity and permeability. The packing procedure was performed without intensive compacting methods e.g. vibration, etc. Obtained
results show that the parameter n is a function of the volume fraction of large particles xD and, for spherical particles, lies in the range 0.4â0.5. The explanation for this variation is (1) a distortion effect on the small particles arrangement occurring near the large particle surface; (2) in the region
of minimum porosity, near contact points of large particles, the occurrence of dead zones that are free of small particles. A relationship accounting for this effect is proposed that may be useful for the analysis of transport phenomena in granular bed filters, chromatographic columns, etc.Fundação para a CiĂȘncia e a Tecnologia FCT); FEDE
Particulate binary mixtures : dependence of packing porosity on particle size ratio
Binary mixtures with significant size ratios are scarcely studied. Yet, contaminants of
chromatographic columns or ion-exchange resins have size ratios of delta < 0.1. Binary mixtures of
glass beads with delta = 0.1-0.0375 were used experimentally to measure packing porosity.
Simultaneously, a significant number of published data was analyzed. A linear mixing model
was adopted to predict the porosity of each particle fraction in the binary mixture. Deviations
from the model may be caused by wedging of small particles between the large ones. Large
particles may disturb the porous medium properties by inducing a wall effect over the small
particles. Wedging analysis led to the conclusion that, for delta < 0.01, its effect is insignificant.
The wall effect yields an additional void around the large particles as long as delta > 0.0035. For
delta < 0.0035, the small particles form a monosized dense packing and both wedging and wall effects become negligible.Fundação para a CiĂȘncia e a Tecnologia (FCT) e FEDER â POCTI/EQU/37500/2001
Effect of real particles packing with large size ratio on porosity and tortuosity of filter bed
The complexity of processes involved in the formation of granular beds results in
limited information about permeability Îș , which directly rela tes with packing porosity Δ and
tortuosity T . For a mixed bed of particles significantly different in size, the influence of
packing affects permeability. For a better understanding of the underlying relationship
between Îș , Δ , and T in mixed beds of particles significantly different in size, simplified
porous media model of binary mixture of spheres were used. Boundary analysis of the binary
packing showed that the approach based on the fractional porosity of large and small size
particle fractions gives a tool for Δ control. This approach allows a new insight into the
mixture structure and provides explanation for the different types of the obtained porosity.
Binary packing of glass beads with size ratios 13.3, 20, and 26.7 were investigated. As a
basic relation for the dependence of T on Δ, at different volume fraction xD of large
particles in the mixture, the formula T=1/ Δ⿠was used. The obtained experimental results
show that the parameter n is a function of the packing content xD and may vary in the range
of 0.4-0.5. The reason for n variation was explained by the wall effect of the small particles
arrangement occurring near the large particles surface. A model accounting for this effect is
proposed and may be useful for transport phenomena analysis in granular bed filters.Fundação para a CiĂȘncia e a Tecnologia (FCT) â Programa Operacional âCiĂȘncia, Tecnologia, Inovaçãoâ (POCTI) - POCTI/EQU/37500/2001.UniĂŁo Europeia (UE). Fundo Europeu de Desenvolvimento Regional (FEDER)
Application of binary packing for starch separation by hydrodynamic chromatography
Columns packed with commercial glass beads of 5 and 19 microns average diameter
and binary mixtures with finest fraction of 5 micron (30 % volume fraction of the
mixture) were used to analyse starch by hydrodynamic chromatography (HDC).
Experiments were carried out at 3 and 15 ÂșC. The observed resolution increased with
the application of binary packing as compared with single-size packing. The best
results were obtained at starchâs amylopectin and amylose separation with a glass
beads mixture (5 + 19 micron) at 3ÂșC. In what concerns amylopectin and amylose
separation, a lower pressure drop were obtained for the mixed binary packing when
compared with the packing containing uniform 5 micron glass beads. For the Hylon VII
starch RRT were 0.777 and 0.964 for amylopectin (AP) and amylose (AM),
respectively, while for the Tapioca starch the obtained RRTs were 0.799 and 0.923.
Application of unbound glass beads as column packing might reduce equipment and
running costs in preparative scale separations.Fundação para a CiĂȘncia e a Tecnologia (FCT) .FEDER - projecto POCI_EQU_58337/200
Functional respiratory re-education interventions in people with respiratory disease: a systematic literature review
Objectives: to identify nursing interventions in rehabilitation, within the scope of functional respiratory reeducation, which allow a respiratory function improvement in people with respiratory disease. Methods: systematic literature review using the MEDLINE database search, adopting the PICO mnemonic and the Joanna Briggs Instituteâs assessment of the level of evidence and methodological quality. The search for randomized controlled trials was carried out in June 2021 considering the period from 2015 to 2020, in English or Portuguese. Results: a sample of nine randomized controlled trials with methodological quality was obtained which highlighted the use of positive expiratory pressure devices as an importantcomponent and intervention for respiratory functional reeducation. Conclusions: nursing interventions in rehabilitation with an emphasis on functional respiratory reeducation are essential, showing improvements in peopleâs general health
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