2,923 research outputs found
Asymptotic linearity and limit distributions, approximations.
Linear and quadratic forms as well as other low degree polynomials play an important
role in statistical inference. Asymptotic results and limit distributions are obtained for a
class of statistics depending on m þ X, with X any random vector and m non-random
vector with JmJ-þ1. This class contain the polynomials in m þ X. An application to
the case of normal X is presented. This application includes a new central limit theorem
which is connected with the increase of non-centrality for samples of fixed size.
Moreover upper bounds for the suprema of the differences between exact and
approximate distributions and their quantiles are obtained
Influence of seismic activity on the atmospheric electric field in Lisbon (Portugal) from 1955 to 1991
In the present study, we considered the influence of seismic activity on the atmospheric electric field recorded at Portela meteorological station (Lisbon, Portugal) for the period from 1955 to 1991. To this end, an exploratory method was developed, which involved the selection of events for which the distance from the atmospheric electrical field sensor to the earthquake epicenter is smaller than the preparation radius of the event. This enabled the correlation of the atmospheric electric field variations with a quantity S, defined basically as the ratio of the earthquake preparation radius to the distance between the sensor and the event epicenter. The first results
show promising perspectives, but clearly a more profound study is required, in which a careful analysis of the weather conditions and other variables, like atmospheric radon levels, must be considered
Aesthetic markers in the voice of radio professionals
Voice is one of the most essential means of expression in human experience and a valuable tool for communication. Its sound characteristics are most relevant in contexts such as social communication and particularly the radio, where the practice of communication is treated at a professional level and the need to captivate a public-listener through the vocal resources is identified. Therefore, this study intended to find if there are specific vocal qualities that contribute to a better or worse appreciation of vocal aesthetic of the radio professional concerning experienced radio listeners.info:eu-repo/semantics/publishedVersio
Serologic diagnosis of Toxoplasma gondii in swines slaughtered without inspection in Northern Brazil
Enumeration and characterization of arsenic-tolerant diazotrophic bacteria in a long-term heavy-metal-contaminated soil
The abundance of arsenic-tolerant diazotrophic
bacteria was compared in a long-term contaminated
soil versus a non-contaminated one. In addition, the
characterization of tolerant diazotrophic bacteria was
carried out. Differences in the number of heterotrophic
N2 fixers were found between soils. Contaminated soil
showed a decrease in the microbial population size of
about 80%, confirming the great sensitivity of this
group of soil bacteria to metals. However, quantitative
analysis of the response to increased doses of arsenic
reveals that the proportion of the culturable diazotrophic
community tolerant to arsenic was identical for both
soils (contaminated and non-contaminated). Twentytwo
arsenic-tolerant diazotrophic isolates were obtained
and further characterized. 16S ribosomal DNA sequence
analysis revealed that these bacterial isolates
were distributed among four taxons (Actinobacteria,
Firmicutes, γ-Proteobacteria, and β-Proteobacteria).
Most genera recovered from the contaminated soil were
also found in the uncontaminated soi
Spatial-temporal evaluation of water quality in Brazilian semiarid Reservoirs
Reservoirs are used in the Brazilian semiarid for human supply, power generation, irrigated agriculture and
more recently, intensive fish farming, the Sobradinho reservoir being the largest of this region. In the last
decade, the semiarid region has suffered a strong drought, in opposite direction to the increasing demand
of multiple water uses. The present work aims to study the spatial-temporal variation of water quality in
two reservoirs in the Brazilian semiarid region (Sobradinho and Itaparica reservoirs). For this, samples were
collected in the dry and wet periods between 2011 and 2014, and the results were analyzed through boxplot
charts and Principal Component Analysis (PCA). For both reservoirs, our results showed that the PCAs did not
evidence a specific seasonal change in the water quality characteristics, distinguishing the wet and dry periods
through the four years studied. A clear temporal pattern was detected in both reservoirs, with higher values of
turbidity, dissolved oxygen and total phosphorus in the wet period and higher values of pH and alkalinity in the
dry period. An upstream reduction of nutrients and turbidity was not found in this study, as is reported in literature for consecutive reservoirs, probably due to the irrigation and aquaculture activities, mainly in Itaparica
reservoir
Influence of inoculum activity on the bio-methanization of a kitchen waste under different waste/inoculum ratios
The use of a granular inoculum prevented acidification during the anaerobic batch biodegradation of a kitchen waste for waste/inoculum
ratios in the range of 0.5–2.3 g VS/g VS, when the alkalinity/COD ratio was 37mg NaHCO3/g COD. In similar experiments but using a
suspended sludge with a significantly lower activity, the methane production rates and the biodegradability were significantly lower and the
pH decreased below 5.5 at the waste/inoculum ratio of 2.3 g VS/g VS. When the added alkalinity was decreased to 2mg NaHCO3/g COD,
the ratio waste/inoculum was clearly more important than the inoculum activity, since, irrespective of the sludge used, acidification occurred
at waste/inoculum ratios higher than 0.5 g VS/g VS. The advantage of using granular sludge was further investigated in order to define
reasonable condition of waste/inoculum ratio and added alkalinity that could be applied in practice. For a waste/inoculum ratio of 1.35, there
were no significant differences between the results obtained for the biodegradability and maximum methane production rate (MMPR), when
the alkalinity decreased from 44 to 22 mg NaHCO3/g COD.Fundação para a Ciência e Tecnologia (FCT) - Project POCTI/1999/CTA/36524
Gravitational non-commutativity and G\"odel-like spacetimes
We derive general conditions under which geodesics of stationary spacetimes
resemble trajectories of charged particles in an electromagnetic field. For
large curvatures (analogous to strong magnetic fields), the quantum
mechanicical states of these particles are confined to gravitational analogs of
{\it lowest Landau levels}. Furthermore, there is an effective
non-commutativity between their spatial coordinates. We point out that the
Som-Raychaudhuri and G\"odel spacetime and its generalisations are precisely of
the above type and compute the effective non-commutativities that they induce.
We show that the non-commutativity for G\"odel spacetime is identical to that
on the fuzzy sphere. Finally, we show how the star product naturally emerges in
Som-Raychaudhuri spacetimes.Comment: Two sections added (Relation to the fuzzy sphere, Emergence of the
star product). 10 pages, Revtex. To appear in General Relativity and
Gravitatio
A PRÁTICA DOCENTE COMO AÇÃO POLÍTICA: UM OLHAR HISTÓRICO
This article discusses contemporary educational trends regarding teaching and that points ways to teacher pedagogic practice. The objective is to make clear that the existence of these trends does not constitute a particularity of our time, but, in the contrary, that in all historical periods there have been projects aiming at finding solutions for education. However, what is now presented is a brief retrospective of modern educational proposals, after that an analysis of contemporary proposals, especially those that have appeared since the XIX century. The theme which guides our approach is the understanding of educational ideas within their historical context and, effectively,to analyze them as an expression of political trends at a given time.Este artigo tem como propósito discutir as tendências contemporâneas da Educação que apontam caminhos para a prática pedagógica do docente. O intuito é explicitar que a existências dessas tendências não constitui uma particularidade de nossa época, mas, ao contrário, em todas as épocas históricas existiram projetos buscando soluções para a educação. Contudo, o que ora se apresenta no texto é uma breve retrospectiva de propostas educativas na modernidade para, em seguida, analisarmos com vagar, as contemporâneas, especificamente aquelas que surgiram a partir do século XIX. O fio condutor que norteia nossa abordagem é o entendimento das idéias educacionais dentro de seu contexto histórico e, efetivamente, analisá-las como expressão de tendências políticas de um dado momento
Resistance of cattle of various genetic groups to the tick Rhipicephalus microplus and the relationship with coat traits
AbstractThis study evaluated the resistance of cattle of different genetic groups to the tick Rhipicephalus microplus and the relationship with traits of the animals’ hair and coat. Cows of the Senepol×Nelore (SN), Angus×Nelore (AN) and Nelore (NX) genetic groups were submitted to four consecutive artificial infestations, at 14-day intervals, each one with approximately 20,000 tick larvae placed on the animals’ lumbar region. From the 19th to 23rd day of each infestation five counts of the number of ticks were performed on each animal's left body side. The tick count data (TTC) were transformed into log10 (n+1), and also into percentage of return (PR), where n is the total number of ticks counted at each infestation. Hair samples were collected 24h after the last infestation with flat-nosed pliers. Measures of the average hair length (HL), coat thickness (CT), number of hairs per cm2 (NHCM2) and weight of the samples (SW) were obtained. Pearson's correlation coefficients were calculated within genetic group to measure association between PR and the hair and coat data. There was a significant difference among genetic groups for the number of ticks, with the AN group having higher counts than the SN and NX groups. For the hair and coat traits, the NX and SN groups had lower values of HL and SW than did the AN group. The SN genetic group had lower NHCM2 counts than the NX and AN groups. There were positive correlations between TTC and CT (P<0.05) and SW (P<0.05) in the SN group. No significant correlation was found for the AN genetic group (P>0.05)
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