405 research outputs found
Conventions spreading in open-ended systems
We introduce a simple open-ended model that describes the emergence of a
shared vocabulary. The ordering transition toward consensus is generated only
by an agreement mechanism. This interaction defines a finite and small number
of states, despite each individual having the ability to invent an unlimited
number of new words. The existence of a phase transition is studied by
analyzing the convergence times, the cognitive efforts of the agents and the
scaling behavior in memory and timeComment: 11 pages, 5 figure
Consequence of reputation in an open-ended Naming Game
We study a modified version of the Naming Game, a recently introduced model
which describes how shared vocabulary can emerge spontaneously in a population
without any central control. In particular, we introduce a new mechanism that
allows a continuous interchange with the external inventory of words. A novel
playing strategy, influenced by the hierarchical structure that individuals'
reputation defines in the community, is implemented. We analyze how these
features influence the convergence times, the cognitive efforts of the agents
and the scaling behavior in memory and time.Comment: 6 pages, 6 figure
Produção e purificação de proteĂna recombinante de A. marginale e Babesia sp.
Comissão organizadora: Grácia Maria Soares Rosinha, Alexandra Rocha de Oliveir, Rodrigo Carvalho Alva
Correlation between the progression of optic disc and visual field changes in glaucoma
Visual field test and optic disc evaluation are the standard examination techniques used to detect the onset and progression of glaucoma. This explorative study was performed to assess the temporal correlation between visual field and optic disc changes in eyes with ocular hypertension and well-established glaucoma. Eighty-six hypertensive and 16 glaucomatous eyes were followed up for a period of up to 9 years (average 4.4 yrs) using kinetic and computerized static perimetry and optic disc manual morphometry. Perimetric changes were based on a series of strict criteria and optic disc changes were based as a reduction in the baseline rim area/disc area ratio (R/D) measurement exceeding the 99% confidence interval for intraobserver reproducibility (7.7%). Optic disc changes were found prior to visual field changes in four hypertensive eyes, whereas visual field changes were found prior to disc changes in six glaucomatous eyes (p = 0.042). The results of our explorative study suggest that quantitative optic disc analysis may be more sensitive than visual field examination in detecting early glaucomatous changes, whereas visual field examination may be more sensitive than quantitative optic disc analysis in detecting glaucomatous progressions in eyes with well established glaucoma
Interlayer-confined Cu(II) complex as an efficient and long-lasting catalyst for oxidation of H2s on montmorillonite
Removal of highly toxic H2S for pollution control and operational safety is a pressing need. For this purpose, a montmorillonite intercalated with Cu(II)-phenanthroline complex [Cu[(Phen)(H2O)2]2+ (Mt-CuPhen) was prepared to capture gaseous H2S under mild conditions. This hybrid material was simple to obtain and demonstrated an outstanding ability to entrap H2S at room temperature, retaining high efficiency for a very long time (up to 36.8 g of S/100 g Mt-CuPhen after 3 months of exposure). Sorbent and H2S uptake were investigated by elemental analysis, X-ray powder diffraction measurements, diffuse reflectance (DR) UV\u2013Vis and infrared spectroscopy, thermal analysis and evolved gas mass spectrometry, scanning electron microscopy equipped with energy-dispersive X-ray spectrometer, and X-ray absorption spectroscopy. The H2S capture was studied over time and a mechanism of action was proposed. The entrapping involves a catalytic mechanism in which [Cu[(Phen)(H2O)2]2+ acts as catalyst for H2S oxidation to S0 by atmospheric oxygen. The low cost and the long-lasting performance for H2S removal render Mt-CuPhen an extremely appealing trap for H2S removal and a promising material for many technological applications
Detection of antibodies directed to the N-terminal region of GAD is dependent on assay format and contributes to differences in the specificity of GAD autoantibody assays for type 1 diabetes
Autoantibodies to glutamate decarboxylase (GADA) are sensitive markers of islet autoimmunity and type 1 diabetes. They form the basis of robust prediction models and are widely used for recruitment of subjects at high risk of type 1 diabetes to prevention trials. However GADA are also found in many individuals at low risk of diabetes progression. To identify the sources of diabetes irrelevant GADA reactivity therefore, we analyzed data from the 2009 and 2010 Diabetes Autoantibody Standardization Program GADA workshop and found that binding of healthy control sera varied according to assay type. Characterization of control sera found positive by radiobinding assay, but negative by ELISA showed that many of these sera reacted to epitopes in the N-terminal region of the molecule. This finding prompted development of an N-terminally truncated GAD65 radiolabel, (35)S-GAD65(96-585), which improved the performance of most GADA radiobinding assays (RBAs) participating in an Islet Autoantibody Standardization Program GADA substudy. These detailed workshop comparisons have identified a source of disease-irrelevant signals in GADA RBAs and suggest that N-terminally truncated GAD labels will enable more specific measurement of GADA in type 1 diabetes
Patchiness and Demographic Noise in Three Ecological Examples
Understanding the causes and effects of spatial aggregation is one of the
most fundamental problems in ecology. Aggregation is an emergent phenomenon
arising from the interactions between the individuals of the population, able
to sense only -at most- local densities of their cohorts. Thus, taking into
account the individual-level interactions and fluctuations is essential to
reach a correct description of the population. Classic deterministic equations
are suitable to describe some aspects of the population, but leave out features
related to the stochasticity inherent to the discreteness of the individuals.
Stochastic equations for the population do account for these
fluctuation-generated effects by means of demographic noise terms but, owing to
their complexity, they can be difficult (or, at times, impossible) to deal
with. Even when they can be written in a simple form, they are still difficult
to numerically integrate due to the presence of the "square-root" intrinsic
noise. In this paper, we discuss a simple way to add the effect of demographic
stochasticity to three classic, deterministic ecological examples where
aggregation plays an important role. We study the resulting equations using a
recently-introduced integration scheme especially devised to integrate
numerically stochastic equations with demographic noise. Aimed at scrutinizing
the ability of these stochastic examples to show aggregation, we find that the
three systems not only show patchy configurations, but also undergo a phase
transition belonging to the directed percolation universality class.Comment: 20 pages, 5 figures. To appear in J. Stat. Phy
New results on solar neutrino fluxes from 192 days of Borexino data
We report the direct measurement of the ^7Be solar neutrino signal rate
performed with the Borexino detector at the Laboratori Nazionali del Gran
Sasso. The interaction rate of the 0.862 MeV ^7Be neutrinos is
49+-3(stat)+-4(syst) counts/(day * 100ton). The hypothesis of no oscillation
for ^7Be solar neutrinos is inconsistent with our measurement at the 4sigma
level. Our result is the first direct measurement of the survival probability
for solar nu_e in the transition region between matter-enhanced and
vacuum-driven oscillations. The measurement improves the experimental
determination of the flux of ^7Be, pp, and CNO solar nu_e, and the limit on the
magnetic moment of neutrinos
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