On the basic reproduction number and the topological properties of the contact network: An epidemiological study in mainly locally connected cellular automata

We study the spreading of contagious diseases in a population of constant size using susceptible-infective-recovered (SIR) models described in terms of ordinary differential equations (ODEs) and probabilistic cellular automata (PCA). In the PCA model, each individual (represented by a cell in the lattice) is mainly locally connected to others. We investigate how the topological properties of the random network representing contacts among individuals influence the transient behavior and the permanent regime of the epidemiological system described by ODE and PCA. Our main conclusions are: (1) the basic reproduction number (commonly called R(0)) related to a disease propagation in a population cannot be uniquely determined from some features of transient behavior of the infective group; (2) R(0) cannot be associated to a unique combination of clustering coefficient and average shortest path length characterizing the contact network. We discuss how these results can embarrass the specification of control strategies for combating disease propagations. (C) 2009 Elsevier B.V. All rights reserved.

Frequency Domain Connectivity Identification: An Application of Partial Directed Coherence in fMRI

Functional magnetic resonance imaging (fMRI) has become an important tool in Neuroscience due to its noninvasive and high spatial resolution properties compared to other methods like PET or EEG. Characterization of the neural connectivity has been the aim of several cognitive researches, as the interactions among cortical areas lie at the heart of many brain dysfunctions and mental disorders. Several methods like correlation analysis, structural equation modeling, and dynamic causal models have been proposed to quantify connectivity strength. An important concept related to connectivity modeling is Granger causality, which is one of the most popular definitions for the measure of directional dependence between time series. In this article, we propose the application of the partial directed coherence (PDC) for the connectivity analysis of multisubject fMRI data using multivariate bootstrap. PDC is a frequency domain counterpart of Granger causality and has become a very prominent tool in EEG studies. The achieved frequency decomposition of connectivity is useful in separating interactions from neural modules from those originating in scanner noise, breath, and heart beating. Real fMRI dataset of six subjects executing a language processing protocol was used for the analysis of connectivity. Hum Brain Mapp 30:452-461, 2009. (C) 2007 Wiley-Liss, Inc.

Identification and partial characterization of a Carica papaya-infecting isolate of Alfalfa mosaic virus in Brazil

A Carica papaya plant with severe yellow leaf mosaic, leaf distortion, and systemic necrosis was found in the municipality of Piracicaba, state of So Paulo, Brazil. Transmission electron microscopy (TEM) analysis revealed the presence of potyvirus-like particles and bacilliform particles similar to those of the Alfamovirus genus. The potyvirus was identified as Papaya ringspot virus-type P (PRSV-P). Biological, serological, and molecular studies confirmed the bacilliform virus as an isolate of Alfalfa mosaic virus (AMV). Partial nucleotide and amino acid sequences of the coat protein gene of this AMV isolate shared 97-98% identity with the AMV isolates in the GenBank database. This report is the first of the natural infection of papaya plants by AMV.

Effect of the Partial Substitution of Soy Proteins by Highly Methyl-esterified Pectin on Chemical and Sensory Characteristics of Sausages

Pectin can be used as a natural emulsifier in food formulations. In this study, textured soybean protein (TSP), used as an emulsifier in commercial sausages, was partially replaced by a mixture containing pectin and isolated soybean proteins, which were either extruded (EXT) or not extruded (MIX), and the chemical and sensory characteristics of samples were evaluated after 60 days of storage at 4 degrees C. Responses such as oxidation measured by PV and TBARS, hardness, color, pH and sensory characteristics were compared with those of a commercial sausage (CON). The mixture containing highly methyl-esterified pectin, textured soybean proteins and isolated soybean proteins, as emulsifier agent, reduced the hardness (EXT: 21.69 +/- 0.98 and MIX: 20.17 +/- 2.76 N) and the pH (EXT: 5.46 +/- 0.03 and MIX: 5.29 +/- 0.01) of the samples and increased the concentration of peroxides (EXT: 0.10 +/- 0.01 and MIX: 0.15 +/- 0.01 meq/kg) when compared with samples formulated only with TSP (28.57 +/- 2.54 N, pH of 6.92 +/- 0.04 and PV = 0.07 +/- 0.01 meq/kg). These effects were likely caused by the anionic character of the emulsifier. However, no sensory difference was observed between the sausages containing highly methyl-esterified pectin, textured soybean proteins and isolated soybean proteins submitted to the extrusion process (EXT) and the control sausages, suggesting that the formulation proposed in this study can be a potential alternative for the further development of sausages that have functional properties or are free of artificial additives.

Manufacture of low-sodium Minas fresh cheese: Effect of the partial replacement of sodium chloride with potassium chloride

We investigated the effect of sodium reduction by partial substitution of sodium chloride (NaCl) with potassium chloride (KCl) on the manufacture of Minas fresh cheese during 21 d of refrigerated storage. Four treatments of low-sodium Minas fresh cheese were manufactured, with partial replacement of NaCl by KCl at 0, 25, 50, and 75% (wt/wt), respectively. The cheeses showed differences in the content of moisture, ash, protein, salt, and lipid contents, as well as on the extent of proteolysis and hardness throughout the storage period. However, no difference was observed among treatments within each storage day tested. The partial substitution of NaCl by KCl decreased up to 51.8% the sodium concentration of the cheeses produced. The consumer test indicated that it is possible to manufacture a low-sodium Minas fresh cheese that is acceptable to consumers by partial substitution of NaCl by KCl at 25% (wt/wt) in the salting step.

Isolation, functional, and partial biochemical characterization of galatrox, an acidic lectin from Bothrops atrox snake venom

Snake venom lectins have been studied in regard to their chemical structure and biological functions. However, little is known about lectins isolated from Bothrops atrox snake venom. We report here the isolation and partial functional and biochemical characterization of an acidic glycan-binding protein called galatrox from this venom. This lectin was purified by affinity chromatography using a lactosyl-sepharose column, and its homogeneity and molecular mass were evaluated by high-performance liquid chromatography, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and matrix-assisted laser desorption/ionization-time-of-flight mass spectrometry. The purified galatrox was homogeneous and characterized as an acidic protein (pI 5.2) with a monomeric and dimeric molecular mass of 16.2 and 32.5 kDa, respectively. Alignment of N-terminal and internal amino acid sequences of galatrox indicated that this protein exhibits high homology to other C-type snake venom lectins. Galatrox showed optimal hemagglutinating activity at a concentration of 100 mu g/ml and this effect was drastically inhibited by lactose, ethylenediaminetetraacetic acid, and heating, which confirmed galatrox`s lectin activity. While galatrox failed to induce the same level of paw edema or mast cell degranulation as B. atrox crude venom, galatrox did alter cellular viability, which suggested that galatrox might contribute to venom toxicity by directly inducing cell death.

Partial characterization of proteins from baru (Dipteryx alata Vog) seeds

BACKGROUND: Baru (Dipteryx alata Vog.) is a fruit distributed throughout the Brazilian savanna and contains a seed with a high protein content, whose properties have been rarely explored. The purpose of this study was to characterize this protein, especially by isolation and quantifying its fractions and measuring some of its molecular properties. RESULTS: Baru seeds contain 244 g kg(-1) protein on a dry weight basis. Solubility profiles showed a preponderance of globulins. This fraction dominated the seed composition, with 61.7 wt% of the total soluble proteins. Albumins and glutelins accounted for 14 and 3.3 wt%, respectively. SDS-PAGE resolution of albumin and globulin showed main bands with molecular weights of 84 kDa and 64,66 and 73 kDa, respectively. The total protein of the flour and the globulin showed values of in vitro digestibility of 85.59% and 90.54%, relative to casein. Total globulin produced only one chromatographic peak, both on Sepharose CL-6B gel filtration and on DEAE-cellulose ion-exchange columns, eluted at a concentration of 0.12 mol L(-1) NaCl. CONCLUSION: The baru seed had high protein content with large quantities of storage proteins. The chromatographic and solubility profiles indicate the predominance of a fraction with characteristics of a legumin-type protein. (C) 2011 Society of Chemical Industry

Random numbers from astronomical imaging

This article describes a method to turn astronomical imaging into a random number generator by using the positions of incident cosmic rays and hot pixels to generate bit streams. We subject the resultant bit streams to a battery of standard benchmark statistical tests for randomness and show that these bit streams are statistically the same as a perfect random bit stream. Strategies for improving and building upon this method are outlined.

Evidence for a global Wolbachia replacement in Drosophila melanogaster

Wolbachia are maternally inherited intracellular α-Proteobacteria found in numerous arthropod and filarial nematode species [1, 2 and 3]. They influence the biology of their hosts in many ways. In some cases, they act as obligate mutualists and are required for the normal development and reproduction of the host [4 and 5]. They are best known, however, for the various reproductive parasitism traits that they can generate in infected hosts. These include cytoplasmic incompatibility (CI) between individuals of different infection status, the parthenogenetic production of females, the selective killing of male embryos, and the feminization of genetic males [1 and 2]. Wolbachia infections of Drosophila melanogaster are extremely common in both wild populations and long-term laboratory stocks [6, 7 and 8]. Utilizing the newly completed genome sequence of Wolbachia pipientis wMel [9], we have identified a number of polymorphic markers that can be used to discriminate among five different Wolbachia variants within what was previously thought to be the single clonal infection of D. melanogaster. Analysis of long-term lab stocks together with wild-caught flies indicates that one of these variants has replaced the others globally within the last century. This is the first report of a global replacement of a Wolbachia strain in an insect host species. The sweep is at odds with current theory that cannot explain how Wolbachia can invade this host species given the observed cytoplasmic incompatibility characteristics of Wolbachia infections in D. melanogaster in the field [6].

Wolbachia infections and arthropod reproduction

Wolbachia is an intracellular bacterium that is almost exclusively maternally transmitted, and its reproductive effects favor transmission of the intracellular bacterial agent at the expense of the arthropod population that is not infected. Wolbachia can cause cytoplasmic incompatibility, parthenogenesis and feminization in many arthropods.

Kinetic analysis of vascular marker distribution in perfused rat livers after regeneration following partial hepatectomy

Background/Aims: Liver clearance models are based on information (or assumptions) on solute distribution kinetics within the microvasculatory system, The aim was to study albumin distribution kinetics in regenerated livers and in livers of normal adult rats, Methods: A novel mathematical model was used to evaluate the distribution space and the transit time dispersion of albumin in livers following regeneration after a two-thirds hepatectomy compared to livers of normal adult rats. Outflow curves of albumin measured after bolus injection in single-pass perfused rat livers were analyzed by correcting for the influence of catheters and fitting a long-tailed function to the data. Results: The curves were well described by the proposed model. The distribution volume and the transit time dispersion of albumin observed in the partial hepatectomy group were not significantly different from livers of normal adult rats. Conclusions: These findings suggest that the distribution space and the transit time dispersion of albumin (CV2) is relatively constant irrespective of the presence of rapid and extensive repair. This invariance of CV2 implies, as a first approximation, a similar degree of intrasinusoidal mixing, The finding that a sum of two (instead of one) inverse Gaussian densities is an appropriate empirical function to describe the outflow curve of vascular indicators has consequences for an improved prediction of hepatic solute extraction.

Familial partial epilepsy with variable foci: A new partial epilepsy syndrome with suggestion of linkage to chromosome 2

Familial partial epilepsy with variable foci (FPEVF) joins the recently recognized group of inherited partial epilepsies. We describe an Australian family with 10 individuals with partial seizures over four generations. Detailed electroclinical studies were performed on all affected and 17 clinically unaffected family members. The striking finding was that the clinical features of the seizures and interictal electroencephalographic foci differed among family members and included frontal, temporal, occipital, and centroparietal seizures. Mean age of seizure onset was 13 years (range, 0.75-43 years). Two individuals without seizures had epileptiform abnormalities on electroencephalographic studies. Penetrance of seizures was 62%. A genome-wide search failed to demonstrate definitive linkage, but a suggestion of linkage was found on chromosome 2q with a LOD score of 2.74 at recombination fraction of zero with the marker D2S133. FPEVF differs from the other inherited partial epilepsies where partial seizures in different family members are clinically similar. The inherited nature of this new syndrome may be overlooked because of relatively low penetrance and because of the variability in age at onset and electroclinical features between affected family members.

Long range forecasts of the numbers of Helicoverpa punctigera and H-armigera (Lepidoptera : Noctuidae) in Australia using the Southern Oscillation Index and the Sea Surface Temperature

The use of long-term forecasts of pest pressure is central to better pest management. We relate the Southern Oscillation Index (SOI) and the Sea Surface Temperature (SST) to long-term light-trap catches of the two key moth pests of Australian agriculture, Helicoverpa punctigera (Wallengren) and H. armigera (Hubner), at Narrabri, New South Wales over 11 years, and for H. punctigera only at Turretfield, South Australia over 22 years. At Narrabri, the size of the first spring generation of both species was significantly correlated with the SOI in certain months, sometimes up to 15 months before the date of trapping. Differences in the SOI and SST between significant months were used to build composite variables in multiple regressions which gave fitted values of the trap catches to less than 25% of the observed values. The regressions suggested that useful forecasts of both species could be made 6-15 months ahead. The influence of the two weather variables on trap catches of H. punctigera at Turretfield were not as strong as at Narrabri, probably because the SOI was not as strongly related to rainfall in southern Australia as it is in eastern Australia. The best fits were again given by multiple regressions with SOI plus SST variables, to within 40% of the observed values. The reliability of both variables as predictors of moth numbers may be limited by the lack of stability in the SOI-rainfall correlation over the historical record. As no other data set is available to test the regressions, they can only be tested by future use. The use of long-term forecasts in pest management is discussed, and preliminary analyses of other long sets of insect numbers suggest that the Southern Oscillation Index may be a useful predictor of insect numbers in other parts of the world.