1,036 research outputs found
2000 CKM-Triangle Analysis A Critical Review with Updated Experimental Inputs and Theoretical Parameters
Within the Standard Model, a review of the current determination of the sides
and angles of the CKM unitarity triangle is presented, using experimental
constraints from the measurements of |\epsilon_K|, |V_{ub}/V_{cb}|, \Delta m_d
and from the limit on \Delta m_s, available in September 2000. Results from the
experimental search for {B}^0_s-\bar{B}^0_s oscillations are introduced in the
present analysis using the likelihood. Special attention is devoted to the
determination of the theoretical uncertainties. The purpose of the analysis is
to infer regions where the parameters of interest lie with given probabilities.
The BaBar "95 %, C.L. scanning" method is also commented.Comment: 44 pages (revised version
Bayesian Inference in Processing Experimental Data: Principles and Basic Applications
This report introduces general ideas and some basic methods of the Bayesian
probability theory applied to physics measurements. Our aim is to make the
reader familiar, through examples rather than rigorous formalism, with concepts
such as: model comparison (including the automatic Ockham's Razor filter
provided by the Bayesian approach); parametric inference; quantification of the
uncertainty about the value of physical quantities, also taking into account
systematic effects; role of marginalization; posterior characterization;
predictive distributions; hierarchical modelling and hyperparameters; Gaussian
approximation of the posterior and recovery of conventional methods, especially
maximum likelihood and chi-square fits under well defined conditions; conjugate
priors, transformation invariance and maximum entropy motivated priors; Monte
Carlo estimates of expectation, including a short introduction to Markov Chain
Monte Carlo methods.Comment: 40 pages, 2 figures, invited paper for Reports on Progress in Physic
Effects of age and gender on neural correlates of emotion imagery
Mental imagery is part of people's own internal processing and plays an important role in everyday life, cognition and pathology. The neural network supporting mental imagery is bottom-up modulated by the imagery content. Here, we examined the complex associations of gender and age with the neural mechanisms underlying emotion imagery. We assessed the brain circuits involved in emotion mental imagery (vs. action imagery), controlled by a letter detection task on the same stimuli, chosen to ensure attention to the stimuli and to discourage imagery, in 91 men and women aged 14–65 years using fMRI. In women, compared with men, emotion imagery significantly increased activation within the right putamen, which is involved in emotional processing. Increasing age, significantly decreased mental imagery-related activation in the left insula and cingulate cortex, areas involved in awareness of ones' internal states, and it significantly decreased emotion verbs-related activation in the left putamen, which is part of the limbic system. This finding suggests a top-down mechanism by which gender and age, in interaction with bottom-up effect of type of stimulus, or directly, can modulate the brain mechanisms underlying mental imagery
A population-based approach to background discrimination in particle physics
Background properties in experimental particle physics are typically
estimated using control samples corresponding to large numbers of events. This
can provide precise knowledge of average background distributions, but
typically does not consider the effect of fluctuations in a data set of
interest. A novel approach based on mixture model decomposition is presented as
a way to estimate the effect of fluctuations on the shapes of probability
distributions in a given data set, with a view to improving on the knowledge of
background distributions obtained from control samples. Events are treated as
heterogeneous populations comprising particles originating from different
processes, and individual particles are mapped to a process of interest on a
probabilistic basis. The proposed approach makes it possible to extract from
the data information about the effect of fluctuations that would otherwise be
lost using traditional methods based on high-statistics control samples. A
feasibility study on Monte Carlo is presented, together with a comparison with
existing techniques. Finally, the prospects for the development of tools for
intensive offline analysis of individual events at the Large Hadron Collider
are discussed.Comment: Updated according to the version published in J. Phys.: Conf. Ser.
Minor changes have been made to the text with respect to the published
article with a view to improving readabilit
Frequency and duration of SARS-CoV-2 shedding in oral fluid samples assessed by a modified commercial rapid molecular assay
Background: RT-PCR on nasopharyngeal (NPS)/oropharyngeal swabs is the gold standard for diagnosis of SARS-CoV-2 infection and viral load monitoring. Oral fluid (OF) is an alternate clinical sample, easy and safer to collect and could be useful for COVID-19 diagnosis, monitoring viral load and shedding. Methods: Optimal assay conditions and analytical sensitivity were established for the commercial Simplexa™ COVID-19 Direct assay adapted to OF matrix. The assay was used to test 337 OF and NPS specimens collected in parallel from 164 hospitalized patients; 50 bronchoalveolar lavage (BAL) specimens from a subgroup of severe COVID-19 cases were also analysed. Results: Using Simplexa™ COVID-19 Direct on OF matrix, 100% analytical detection down to 1 TCID50/mL (corresponding to 4 × 103 copies (cp)/mL) was observed. No crossreaction with other viruses transmitted through the respiratory toute was observed. Parallel testing of 337 OF and NPS samples showed highly concordant results (κ = 0.831; 95 % CI = 0.771–0.891), and high correlation of Ct values (r = 0.921; p < 0.0001). High concordance and elevated correlation was observed also between OF and BAL. Prolonged viral RNA shedding was observed up to 100 days from symptoms onset (DSO), with 32% and 29% positivity observed in OF and NPS samples, respectively, collected between 60 and 100 DSO. Conclusions: Simplexa™ COVID-19 Direct assays on OF have high sensitivity and specificity to detect SARS-CoV-2 RNA and provide an alternative to NPS for diagnosis and monitoring SARS-CoV-2 shedding
USO DE SIMULAÇÃO DE EVENTOS DISCRETOS PARA ANÁLISE DA IMPLEMENTAÇÃO DE CONCEITOS DE PRODUÇÃO ENXUTA
A implementação de conceitos de produção enxuta em indústrias de manufatura é uma tarefa complexa e que demanda muita cautela nos momentos de tomada de decisão, a fim de que a organização não perca seu foco estratégico. Assim, o objetivo geral deste trabalho é avaliar os impactos da implementação de conceitos de produção enxuta em um sistema de produção real através do uso de simulação de eventos discretos. Este estudo tem caráter exploratório, uma vez que se optou pela estratégia de estudo de caso, realizado em uma empresa industrial na área de equipamentos e insumos destinados ao setor médico-hospitalar. A coleta de informações e a análise dos dados foram desenvolvidas com base em técnicas quantitativas e de pesquisa documental. Não obstante, este trabalho também tem como objetivos específicos propor o uso de conceitos de produção enxuta no sistema real de produção, simular o sistema real implementando estes conceitos, avaliar os impactos desta implementação e avaliar o uso da simulação como ferramenta de apoio à tomada de decisão
Frequency and Duration of SARS-CoV-2 Shedding in Oral Fluid Samples Assessed by a Modified Commercial Rapid Molecular Assay
Background: RT-PCR on nasopharyngeal (NPS)/oropharyngeal swabs is the gold standard
for diagnosis of SARS-CoV-2 infection and viral load monitoring. Oral fluid (OF) is an alternate
clinical sample, easy and safer to collect and could be useful for COVID-19 diagnosis, monitoring viral
load and shedding. Methods: Optimal assay conditions and analytical sensitivity were established
for the commercial Simplexa™ COVID-19 Direct assay adapted to OF matrix. The assay was
used to test 337 OF and NPS specimens collected in parallel from 164 hospitalized patients;
50 bronchoalveolar lavage (BAL) specimens from a subgroup of severe COVID-19 cases were
also analysed. Results: Using Simplexa™ COVID-19 Direct on OF matrix, 100% analytical detection
down to 1 TCID50/mL (corresponding to 4 × 103
copies (cp)/mL) was observed. No crossreaction
with other viruses transmitted through the respiratory toute was observed. Parallel testing of 337 OF
and NPS samples showed highly concordant results (κ = 0.831; 95 % CI = 0.771–0.891), and high
correlation of Ct values (r = 0.921; p < 0.0001). High concordance and elevated correlation was
observed also between OF and BAL. Prolonged viral RNA shedding was observed up to 100 days
from symptoms onset (DSO), with 32% and 29% positivity observed in OF and NPS samples,
respectively, collected between 60 and 100 DSO. Conclusions: Simplexa™ COVID-19 Direct assays on
OF have high sensitivity and specificity to detect SARS-CoV-2 RNA and provide an alternative to
NPS for diagnosis and monitoring SARS-CoV-2 shedding
Measurement of the Electric and Magnetic Polarizabilities of the Proton
The Compton scattering cross section on the proton has been measured at
laboratory angles of 90 and 135 using tagged photons in the
energy range 70--100 MeV and simultaneously using untagged photons in the range
100--148~MeV. With the aid of dispersion relations, these cross sections were
used to extract the electric and magnetic polarizabilities, and
respectively, of the proton. We find
in agreement with a model-independent dispersion sum rule, and
where the errors shown are statistical, systematic, and model-dependent,
respectively. A comparison with previous experiments is given and global values
for the polarizabilities are extracted.Comment: 35 pages, 11 PostScript figures, uses RevTex 3.
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