747 research outputs found
An artificial immune system for fuzzy-rule induction in data mining
This work proposes a classification-rule discovery algorithm integrating artificial immune systems and fuzzy systems. The algorithm consists of two parts: a sequential covering procedure and a rule evolution procedure. Each antibody (candidate solution) corresponds to a classification rule. The classification of new examples (antigens) considers not only the fitness of a fuzzy rule based on the entire training set, but also the affinity between the rule and the new example. This affinity must be greater than a threshold in order for the fuzzy rule to be activated, and it is proposed an adaptive procedure for computing this threshold for each rule. This paper reports results for the proposed algorithm in several data sets. Results are analyzed with respect to both predictive accuracy and rule set simplicity, and are compared with C4.5rules, a very popular data mining algorithm
An empirical examination of the relation between attention and motivation in computer-based education: a modeling approach
Attention is considered a pre-requisite to achieve greater motivation in the classroom. However, empirical evidence of this relationship in educational setting is scarce since the measurement of attention requires specialized equipment such as clinical electroencephalograms (EEG) or fMR1. With the advent of portable, consumer-oriented EEG it is now possible to estimate levels of attention and shed light onto this relationship in the context of a computer-based educational setting. To that end, students (N=40) interacted for an average of 9.48 minutes (SD = .0018) with an assessment exercise in a virtual world. Participants' attention levels were monitored via a portable EEG and incorporated into an attention model capable of deciding on strategies to correct low levels of attention. The participants' motivation was assessed using a self-reported motivation questionnaire at pre-test and post-test times. The results indicated that students with higher self-reported motivation and self-reported attention answered significantly more correct answers. However, no direct evidence was found of a relation between EEG readings and self-reported attention or self-reported motivation. This suggests student's own perceptions of motivation and attention influence performance. Future work consists of defining new models of attention considering self-perceived attention and motivation as baseline as well as improving the model of attention combining EEG reading with an indication of the students' gaze
Complementarity of the CERN Large Hadron Collider and the International Linear Collider
The next-generation high-energy facilities, the CERN Large Hadron Collider
(LHC) and the prospective International Linear Collider (ILC), are
expected to unravel new structures of matter and forces from the electroweak
scale to the TeV scale. In this report we review the complementary role of LHC
and ILC in drawing a comprehensive and high-precision picture of the mechanism
breaking the electroweak symmetries and generating mass, and the unification of
forces in the frame of supersymmetry.Comment: 14 pages, 17 figures, to be published in "Supersymmetry on the Eve of
the LHC", a special volume of European Physical Journal C, Particles and
Fields (EPJC) in memory of Julius Wes
Indirect search for dark matter: prospects for GLAST
Possible indirect detection of neutralino, through its gamma-ray annihilation
product, by the forthcoming GLAST satellite from our galactic halo, M31, M87
and the dwarf galaxies Draco and Sagittarius is studied. Gamma-ray fluxes are
evaluated for the two representative energy thresholds, 0.1 GeV and 1.0 GeV, at
which the spatial resolution of GLAST varies considerably. Apart from dwarfs
which are described either by a modified Plummer profile or by a
tidally-truncated King profiles, fluxes are compared for halos with central
cusps and cores. It is demonstrated that substructures, irrespective of their
profiles, enhance the gamma-ray emission only marginally. The expected
gamma-ray intensity above 1 GeV at high galactic latitudes is consistent with
the residual emission derived from EGRET data if the density profile has a
central core and the neutralino mass is less than 50 GeV, whereas for a central
cusp only a substantial enhancement would explain the observations. From M31,
the flux can be detected above 0.1 GeV and 1.0 GeV by GLAST only if the
neutralino mass is below 300 GeV and if the density profile has a central cusp,
case in which a significant boost in the gamma-ray emission is produced by the
central black hole. For Sagittarius, the flux above 0.1 GeV is detectable by
GLAST provided the neutralino mass is below 50 GeV. From M87 and Draco the
fluxes are always below the sensitivity limit of GLAST.Comment: 14 Pages, 7 Figures, 3 Tables, version to appear on Physical Review
Fermionic decays of sfermions: a complete discussion at one-loop order
We present a definition of an on-shell renormalization scheme for the
sfermion and chargino-neutralino sector of the Minimal Supersymmetric Standard
Model (MSSM). Then, apply this renormalization framework to the interaction
between charginos/neutralinos and sfermions. A kind of universal corrections is
identified, which allow to define effective chargino/neutralino coupling
matrices. In turn, these interactions generate (universal) non-decoupling terms
that grow as the logarithm of the heavy mass. Therefore the full MSSM spectrum
must be taken into account in the computation of radiative corrections to
observables involving these interactions. As an application we analyze the full
one-loop electroweak radiative corrections to the partial decay widths
\Gamma(\tilde{f} -> f\neut) and \Gamma(\tilde{f} -> f'\cplus) for all sfermion
flavours and generations. These are combined with the QCD corrections to
compute the corrected branching ratios of sfermions. It turns out that the
electroweak corrections can have an important impact on the partial decay
widths, as well as the branching ratios, in wide regions of the parameter
space. The precise value of the corrections is strongly dependent on the
correlation between the different particle masses.Comment: LaTeX 53 pages, 22 figures, 3 tables. Typos correcte
Epidemiologic situation of bovine brucellosis in the State of Mato Grosso, Brazil
Caracterizou-se a brucelose bovina em Mato Grosso por meio de um estudo transversal realizado em 2003 para auxiliar na implementação do Programa Nacional de Controle e Erradicação da Brucelose e Tuberculose. No Estado, estratificado em quatro circuitos pecuários, foram amostrados 13.684 animais, provenientes de 1.152 rebanhos. O protocolo de testes utilizado foi o da triagem com o teste do antígeno acidificado tamponado e os soros reagentes foram testados pelo 2-mercaptoetanol (ME) e concomitantemente retestados pelo teste de Rosa Bengala para resultado conclusivo. As prevalências de focos e de animais infectados foram: 41,2% [38,0-44,4%] e 10,2% [7,4-13,1%], respectivamente. Nos circuitos produtivos, as prevalências de focos foram 36,9% [29,2-45,2%], 27,2% [22,8-32,1%], 40,4% [38,8-46,2%] e 50,3% [44,5-56,1%]; e as prevalências de animais 7,9% [3,0-12,9%], 4,1% [2,8-5,4%], 8,1% [5,2-11,1%] e 15,3% [9,2-21,3%], respectivamente, para os circuitos 1, 2, 3 e 4. Os fatores de risco (odds ratio, OR) associados à condição de foco no Estado foram: exploração de gado de corte (OR= 1,8 [1,2-2,5]), exploração mista (OR=1,8 [1,2-2,7]), número de fêmeas no rebanho de 11 a 50 (OR=4,8 [1,1-20,8]), número de fêmeas no rebanho acima de 51 (OR=6,8 [1,6-29,0]), ocorrência de aborto (OR=1,7 [1,3-2,2]). A brucelose está homogeneamente distribuída no Estado, o que permite uniformidade de medidas sanitárias. Adicionalmente, sugere-se a intensificação da vacinação de fêmeas para todo o Estado. _______________________________________________________________________________________________________ ABSTRACTA study to characterize bovine brucellosis in the State of Mato Grosso was carried out in 2003 in order to support the implementation of the National Program for the Control and Eradication of Bovine Brucellosis. The State was divided into four productive regions, and 13,684 bovines from 1,152 herds were sampled. The serum samples were screened for antibodies to Brucella spp. by the Rose-Bengal test (RBT) and all RBT-positive sera were re-tested by the 2-mercaptoethanol test (2-ME), and again by RBT for confirmation. The prevalence of infected herds and animals in the State of Mato Grosso were 41.2% [38.0-44.4%] and 10.2% [7.4-13.1%], respectively. In the productive regions, the prevalence of infected herds were 36.9% [29.2-45.2%], 27.2% [22.8-32.1%], 40.4% [38.8-46.2%], and 50.3% [44.5-56.1%], respectively; and the prevalence of infected animals were 7.9% [3.0-12.9%], 4.1% [2.8-5.4%], 8.1% [5.2-11.1%], and 15.3% [9.2-21.3%], respectively, for regions 1, 2, 3, and 4. The risk factors (odds ratio, OR) associated with the presence of the infection in the State were: beef cattle farming (OR=1.8 [1.2-2.5]), mixed (beef and dairy) cattle farming (OR=1.8 [1.2-2.7]), farms with 11 to 50 females (OR=4.8 [1.1-20.8]), farms with more than 51 females (OR=6.8 [1.6-29.0]), and occurrence of abortion (OR=1.7 [1.3-2.2]). Given that brucellosis is homogeneously distributed in the State, uniform sanitary measures might be adopted. As a homogeneous additional measure for the State, the intensification of female vaccination is suggested
Soil biochemistry and microbial activity in vineyards under conventional and organic management at Northeast Brazil.
The São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that orgThe São Francisco Submedium Valley is located at the Brazilian semiarid region and is an important center for irrigated fruit growing. This region is responsible for 97% of the national exportation of table grapes, including seedless grapes. Based on the fact that organic fertilization can improve soil quality, we compared the effects of conventional and organic soil management on microbial activity and mycorrhization of seedless grape crops. We measured glomerospores number, most probable number (MPN) of propagules, richness of arbuscular mycorrhizal fungi (AMF) species, AMF root colonization, EE-BRSP production, carbon microbial biomass (C-MB), microbial respiration, fluorescein diacetate hydrolytic activity (FDA) and metabolic coefficient (qCO2). The organic management led to an increase in all variables with the exception of EE-BRSP and qCO2. Mycorrhizal colonization increased from 4.7% in conventional crops to 15.9% in organic crops. Spore number ranged from 4.1 to 12.4 per 50 g-1 soil in both management systems. The most probable number of AMF propagules increased from 79 cm-3 soil in the conventional system to 110 cm-3 soil in the organic system. Microbial carbon, CO2 emission, and FDA activity were increased by 100 to 200% in the organic crop. Thirteen species of AMF were identified, the majority in the organic cultivation system. Acaulospora excavata, Entrophospora infrequens, Glomus sp.3 and Scutellospora sp. were found only in the organically managed crop. S. gregaria was found only in the conventional crop. Organically managed vineyards increased mycorrhization and general soil microbial activity
Mass Bounds on a Very Light Neutralino
Within the Minimal Supersymmetric Standard Model (MSSM) we systematically
investigate the bounds on the mass of the lightest neutralino. We allow for
non-universal gaugino masses and thus even consider massless neutralinos, while
assuming in general that R-parity is conserved. Our main focus are laboratory
constraints. We consider collider data, precision observables, and also rare
meson decays to very light neutralinos. We then discuss the astrophysical and
cosmological implications. We find that a massless neutralino is allowed by all
existing experimental data and astrophysical and cosmological observations.Comment: 36 pages, 13 figures, minor modification in astro-physical bounds.
EPJC versio
Supersymmetry Without Prejudice
We begin an exploration of the physics associated with the general
CP-conserving MSSM with Minimal Flavor Violation, the pMSSM. The 19 soft SUSY
breaking parameters in this scenario are chosen so as to satisfy all existing
experimental and theoretical constraints assuming that the WIMP is a
conventional thermal relic, ie, the lightest neutralino. We scan this parameter
space twice using both flat and log priors for the soft SUSY breaking mass
parameters and compare the results which yield similar conclusions. Detailed
constraints from both LEP and the Tevatron searches play a particularly
important role in obtaining our final model samples. We find that the pMSSM
leads to a much broader set of predictions for the properties of the SUSY
partners as well as for a number of experimental observables than those found
in any of the conventional SUSY breaking scenarios such as mSUGRA. This set of
models can easily lead to atypical expectations for SUSY signals at the LHC.Comment: 61 pages, 24 figs. Refs., figs, and text added, typos fixed; This
version has reduced/bitmapped figs. For a version with better figs please go
to http://www.slac.stanford.edu/~rizz
Produção da cenoura e efeito na fertilidade do solo e nutrição decorrente da solarização do solo para controle da tiririca.
Dentre os desafios do cultivo orgânico de hortaliças destaca-se o controle de plantas daninhas, devido à proibição do uso de herbicidas. Entre as invasoras, a tiririca (Cyperus rotundus L.) é de difícil controle pela sua alta competitividade. A solarização é uma alternativa para desinfestação do solo, a qual consiste em cobri-lo com plástico transparente, com bons resultados no controle da tiririca. A fim de avaliar a influência do preparo e do revolvimento do solo sobre a eficiência da solarização no controle da tiririca, bem como seu posterior efeito sobre o cultivo da cenoura, foi realizado um experimento na Fazendinha Agroecológica, em Seropédica (RJ). O experimento foi disposto em blocos ao acaso com três repetições, em arranjo fatorial 2 x 3 mais uma testemunha adicional, sendo: 1) solo solarizado, preparado (com grade aradora) e revolvido 30 dias após a solarização (manualmente com auxílio de uma enxada); 2) solo solarizado, preparado e revolvido aos 60 dias; 3) solo solarizado, preparado e não revolvido; 4) solo solarizado, não preparado e revolvido aos 30 dias; 5) solo solarizado, não preparado e revolvido aos 60 dias; 6) solo solarizado, não preparado e não revolvido; solo não solarizado, não preparado e não revolvido (testemunha). A solarização iniciou-se em 29/1/2002, e durou cem dias. A solarização reduziu em 86% a infestação de tiririca no cultivo da cenoura. Até 10 cm de profundidade, a temperatura do solo foi superior nas parcelas solarizadas, porém a 5 cm, a solarização foi mais eficiente quando associada ao preparo do solo, não havendo efeito do revolvimento. A solarização aumentou os valores da biomassa microbiana e dos teores de Ca, Mg e P do solo. O desenvolvimento da cenoura foi influenciado pela solarização que resultou em maior produtividade
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