8,845 research outputs found
Cosmic microwave background constraints on the epoch of reionization
We use a compilation of cosmic microwave anisotropy data to constrain the
epoch of reionization in the Universe, as a function of cosmological
parameters. We consider spatially-flat cosmologies, varying the matter density
(the flatness being restored by a cosmological constant), the Hubble
parameter and the spectral index of the primordial power spectrum. Our
results are quoted both in terms of the maximum permitted optical depth to the
last-scattering surface, and in terms of the highest allowed reionization
redshift assuming instantaneous reionization. For critical-density models,
significantly-tilted power spectra are excluded as they cannot fit the current
data for any amount of reionization, and even scale-invariant models must have
an optical depth to last scattering of below 0.3. For the currently-favoured
low-density model with and a cosmological constant, the
earliest reionization permitted to occur is at around redshift 35, which
roughly coincides with the highest estimate in the literature. We provide
general fitting functions for the maximum permitted optical depth, as a
function of cosmological parameters. We do not consider the inclusion of tensor
perturbations, but if present they would strengthen the upper limits we quote.Comment: 9 pages LaTeX file with ten figures incorporated (uses mn.sty and
epsf). Corrects some equation typos, superseding published versio
Tripartite Graph Clustering for Dynamic Sentiment Analysis on Social Media
The growing popularity of social media (e.g, Twitter) allows users to easily
share information with each other and influence others by expressing their own
sentiments on various subjects. In this work, we propose an unsupervised
\emph{tri-clustering} framework, which analyzes both user-level and tweet-level
sentiments through co-clustering of a tripartite graph. A compelling feature of
the proposed framework is that the quality of sentiment clustering of tweets,
users, and features can be mutually improved by joint clustering. We further
investigate the evolution of user-level sentiments and latent feature vectors
in an online framework and devise an efficient online algorithm to sequentially
update the clustering of tweets, users and features with newly arrived data.
The online framework not only provides better quality of both dynamic
user-level and tweet-level sentiment analysis, but also improves the
computational and storage efficiency. We verified the effectiveness and
efficiency of the proposed approaches on the November 2012 California ballot
Twitter data.Comment: A short version is in Proceeding of the 2014 ACM SIGMOD International
Conference on Management of dat
Diversidade cultural, virulência e agressividade de Rhizoctonia spp. em solos cultivados com feijoeiro comum.
Este trabalho teve como objetivo avaliar a diversidade cultural, a virulência e a agressividade de isolados de Rhizoctonia solani ao feijoeiro comum (Phaseolus vulgaris), provenientes de áreas com histórico de cultivo desta espécie
Densidade populacional de patógenos e antagonistas habitantes do solo em regiões produtoras de feijoeiro comum.
O objetivo deste trabalho foi estimar a densidade das populações de Fusarium solani, Fusarium oxysporum, Rhizoctonia solani e Trichoderma spp. em áreas relevantes para a produção do feijoeiro comum (Phaseolus vulgaris) nos estados do Paraná e de Minas Gerais, os dois principais produtores desta cultura no Brasil
Lattice Model for water-solute mixtures
A lattice model for the study of mixtures of associating liquids is proposed.
Solvent and solute are modeled by adapting the associating lattice gas (ALG)
model. The nature of interaction solute/solvent is controlled by tuning the
energy interactions between the patches of ALG model. We have studied three set
of parameters, resulting on, hydrophilic, inert and hydrophobic interactions.
Extensive Monte Carlo simulations were carried out and the behavior of pure
components and the excess properties of the mixtures have been studied. The
pure components: water (solvent) and solute, have quite similar phase diagrams,
presenting: gas, low density liquid, and high density liquid phases. In the
case of solute, the regions of coexistence are substantially reduced when
compared with both the water and the standard ALG models. A numerical procedure
has been developed in order to attain series of results at constant pressure
from simulations of the lattice gas model in the grand canonical ensemble. The
excess properties of the mixtures: volume and enthalpy as the function of the
solute fraction have been studied for different interaction parameters of the
model. Our model is able to reproduce qualitatively well the excess volume and
enthalpy for different aqueous solutions. For the hydrophilic case, we show
that the model is able to reproduce the excess volume and enthalpy of mixtures
of small alcohols and amines. The inert case reproduces the behavior of large
alcohols such as, propanol, butanol and pentanol. For last case (hydrophobic),
the excess properties reproduce the behavior of ionic liquids in aqueous
solution.Comment: 28 pages, 13 figure
Person-centredness in direct care workers caring for residents with dementia: effects of a psycho-educational intervention
YesThis study assessed the effects of a psycho-educational intervention on direct care workers' person-centredness during morning care to residents with dementia. A controlled pretest–posttest study was conducted in four aged-care facilities with 56 direct care workers (female, mean age 44.72 ± 9.02). Two experimental facilities received a psycho-educational intervention comprising person-centred care competences and stress management skills; control facilities received an education-only intervention, without stress support. In total, 112 video-recorded morning care sessions were coded using the Global Behaviour Scale. Both groups reported significantly higher scores on eight of 11 items of the Global Behaviour Scale and on the Global Behaviour Scale total score at posttest (F=10.59; p=0.02). Global Behaviour Scale total score improvements were higher for the experimental group, with values close to significance (F=3.90; p=0.054). The findings suggest that a psycho-educational intervention may increase care workers' person-centredness. Further research is needed to explore the long-term sustainability and extent of its benefits on workers and residents.Foundation for Science and Technolog
Positive regional species-people correlations: A sampling artefact or a key issue for sustainable development?
Many studies are documenting positive large-scale species–
people correlations (Luck, 2007; Schuldt & Assmann, 2010).
The issue is scale dependent: the local association of species
richness and people is in many cases a negative one (Pautasso,
2007; Pecher et al., 2010). This biogeographical
pattern is thus important for conservation. If species-rich
regions are also densely populated, preserving biodiversity
becomes more difficult, ceteris paribus, than if species-rich
regions were sparsely populated. At the same time, positive,
regional species–people correlations are an opportunity for
the biodiversity education of the majority of the human
population and underline the importance of conservation in
human-modified landscapes (e.g. Sheil & Meijaard, 2010;
Ward, 2010)
Is the human population a large-scale indicator of the species richness of ground beetles?
Aim Positive regional correlations between biodiversity and human population
have been detected for several taxonomic groups and geographical regions.
Such correlations could have important conservation implications and have
been mainly attributed to ecological factors, with little testing for an artefactual
explanation: more populated regions may show higher biodiversity because they
are more thoroughly surveyed. We tested the hypothesis that the correlation
between people and herptile diversity in Europe is influenced by survey effor
Utilização de diferentes fontes de carbono por isolados de Fusarium solani.
Objetivou-se com este trabalho ajustar a metodologia para avaliação da diversidade fisiológica entre isolados de F. solani, por meio da utilização de diferentes fontes de carbono metabolizadas pelo patógeno
- …