19,257 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
Linear Invariant Systems Theory for Signal Enhancement
This paper discusses a linear time invariant (LTI) systems approach to signal enhancement via projective subspace techniques. It provides closed form expressions for the frequency response of data adaptive finite impulse response eigenfilters. An illustrative example using speech enhancement is also presented.Este artigo apresenta a aplicação da teoria de sistemas lineares invariantes no tempo (LTI) na análise de técnicas de sub-espaço. A resposta em frequência dos filtros resultantes da decomposição em valores singulares é obtida aplicando as propriedades dos sistemas LTI
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
Extension of Tycho catalog for low-extinction windows in the galactic bulge
We present in this work secondary catalogs up to based on
the Tycho reference frame (ESA, 1997) for 12 selected low-extinction fields
towards the galactic bulge. The observations have been performed with the
Askania-Zeiss Meridian Circle equiped with a CCD camera, located at the
Abrah\~ao de Moraes Observatory (Valinhos, Brazil) and operated by the
Institute of Astronomy and Geophysics, S\~ao Paulo University. The presented
catalog, though not complete, has been designed to help in intensive search
programmes (e.g. microlensing and variable searches) and therefore the selected
standards have a high astrometric and photometric ( band, approximately)
quality. The mean precisions obtained were in , 0.013'' in
, 0.030 for the standard deviation in magnitude and 0.0042 for the
magnitude when weighted with the error bars in each night (in the mean, 42
stars for the catalog of each window). Tables B.1 to B.12 are also available in
eletronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr
(130.79.128.5) or via http://cdsweb.u-strasbg.fr/Abstract.html.Comment: 16 pages, 6 figures, A&A Latex style. Published in A&A
Stellar variability in low-extinction regions towards the Galactic Bulge
Intensive monitoring of low-extinction windows towards the galactic bulge has
provided in the last years valuable information for studies about the dynamics,
kinematics and formation history of this part of the galaxy, mainly by
characterizing the bulge stellar populations (Paczy\'nski, 1996). Since 1997,
we have been conducting an intensive photometric-astrometric survey of the
galactic bulge, with the monitoring of about 120000 stars in 12 windows
uniformly distributed in galactic latitude and longitude (Blanco & Terndrup,
1989 e Blanco, 1988) never before submitted to this kind of survey. For this
purpose, we have used the IAG/USP CCD Meridian Circle of the Abrah\~ao de
Moraes Observatory. The main objective of this work is the identification and
classification of variable objects. In this work we present the set up and
development of the necessary tools for a project like this and the posterior
analysis of our data. We briefly describe the construction of a program to
organize and detect variables among the observed stars, including real time
alerts (for variations greater than 0.3 magnitudes). The preliminary analysis
after the processing of 76 nights of observation yielded 479 variable stars,
from which 96.7 % of them are new. We discuss the preliminary classification of
this variables, based on: a) the observed amplitude of variation; b) the shape
of light curve; c) the expected variable classes among our data and d) the
calculated periods, whenever possible. Finally, we discuss the future
perspectives for the project and for the applications and analysis of the
discovered variable stars.Comment: 10 pages, 14 figures. Accepted by A&A
Nonequilibrium stationary states of 3D self-gravitating systems
Three dimensional self-gravitating systems do not evolve to thermodynamic
equilibrium, but become trapped in nonequilibrium quasistationary states. In
this Letter we present a theory which allows us to a priori predict the
particle distribution in a final quasistationary state to which a
self-gravitating system will evolve from an initial condition which is
isotropic in particle velocities and satisfies a virial constraint 2K=-U, where
K is the total kinetic energy and U is the potential energy of the system
On the determination of flow stress using bulge test and mechanical measurement
The standard uniaxial tensile test is a widely accepted method to obtain relevant properties of sheet metal materials. These fundamental parameters can be used in numerical modeling of sheet forming operations to predict and assess formability and failure analysis. However the range of strain obtained from tensile test is limited and therefore if one will need further information on material behavior, extrapolation of tensile data is performed. The bulge test is an alternative to obtain ranges of deformation higher than tensile test, thus being possible to obtain non-extrapolated data for material behavior. Several methods may be used to obtain stress-strain data from bulge test, but a common concept is behind them, which needs the measurement of bulge pressure, curvature of bulge specimen, its thickness at the pole and the application of membrane theory. Concerning such measurements, optical methods are being used recently but classical mechanical methods are still an alternative with its own strengths. This paper presents the use and development of a mechanical measuring system to be incorporated in a hydraulic bulge test for flow curve determination, which permits real-time data acquisition under controlled strain rates up to high levels of plastic deformation. Numerical simulations of bulge test using FEM are performed and a sensitivity analysis is done for some influencing variables used in measurements, thus giving some directions in the design and use of the experimental mechanical system. Also, first experimental results are presented, showing an efficient testing procedure method for real time data acquisition with a stable evaluation of the flow curve.open11617Nsciescopu
Higher education systems and institutions, São Tomé and Príncipe
São Tomé and Príncipe, officially the Democratic Republic of São Tomé and Príncipe, is a Portuguese-speaking island nation in the Gulf of Guinea approximately 150 miles off the western African coast. An archipelago with only 1001 square km of combined land area and an estimated population around 198,000 inhabitants, it is one of the smallest countries in the world. Since its independence from Portugal in 1975, the country has evolved from a one party, socialist state to a liberal, multiparty democracy assuring ample civil liberties and political rights.
In economic terms the World Bank (2017) describes São Tomé and Principe as a lower middle income developing country with a fragile economy. The main economic activities are the services sector, agriculture, fishing, and a recently growing tourism sector. The country imports most of its consumer goods and relies heavily in public expenditure as the main driver of growth. The life expectancy is 66.6 years and the adult literacy rateinfo:eu-repo/semantics/acceptedVersio
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