Transport on exploding percolation clusters

We propose a simple generalization of the explosive percolation process [Achlioptas et al., Science 323, 1453 (2009)], and investigate its structural and transport properties. In this model, at each step, a set of q unoccupied bonds is randomly chosen. Each of these bonds is then associated with a weight given by the product of the cluster sizes that they would potentially connect, and only that bond among the q-set which has the smallest weight becomes occupied. Our results indicate that, at criticality, all finite-size scaling exponents for the spanning cluster, the conducting backbone, the cutting bonds, and the global conductance of the system, change continuously and significantly with q. Surprisingly, we also observe that systems with intermediate values of q display the worst conductive performance. This is explained by the strong inhibition of loops in the spanning cluster, resulting in a substantially smaller associated conducting backbone.Comment: 4 pages, 4 figure

Diversidade, preferência alimentar e distribuição vertical de Tripes (Thysanoptera : Thripidae) em mangueira, no semi-árido nordestino.

Este trabalho teve como objetivos: conhecer a diversidade, as estruturas vegetaispreferidas e a distribuição vertical dos tripes na mangueira.1 CD-ROM

A Hamiltonian approach for explosive percolation

We introduce a cluster growth process that provides a clear connection between equilibrium statistical mechanics and an explosive percolation model similar to the one recently proposed by Achlioptas et al. [Science 323, 1453 (2009)]. We show that the following two ingredients are essential for obtaining an abrupt (first-order) transition in the fraction of the system occupied by the largest cluster: (i) the size of all growing clusters should be kept approximately the same, and (ii) the inclusion of merging bonds (i.e., bonds connecting vertices in different clusters) should dominate with respect to the redundant bonds (i.e., bonds connecting vertices in the same cluster). Moreover, in the extreme limit where only merging bonds are present, a complete enumeration scheme based on tree-like graphs can be used to obtain an exact solution of our model that displays a first-order transition. Finally, the proposed mechanism can be viewed as a generalization of standard percolation that discloses an entirely new family of models with potential application in growth and fragmentation processes of real network systems.Comment: 4 pages, 4 figure

A new species of Szelenyiopria Fabritius (Hymenoptera: Diapriidae), larval parasitoid of Acromyrmex subterraneus subterraneus (Forel) (Hymenoptera: Formicidae) from Brazil

Szelenyiopria talitae sp. nov. is described and illustrated. This species is shown to be a larval parasitoid of Acromyrmex subterraneus subterraneus (Forel).Fil: Loiacono, Marta Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Margaría, Cecilia B.. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; ArgentinaFil: Oliveira Moreira, Denise D.. Universidade Federal Fluminense; BrasilFil: Aquino, Daniel Alejandro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - La Plata; Argentina. Universidad Nacional de La Plata. Facultad de Ciencias Naturales y Museo; Argentin

Fracturing highly disordered materials

We investigate the role of disorder on the fracturing process of heterogeneous materials by means of a two-dimensional fuse network model. Our results in the extreme disorder limit reveal that the backbone of the fracture at collapse, namely the subset of the largest fracture that effectively halts the global current, has a fractal dimension of $1.22 \pm 0.01$. This exponent value is compatible with the universality class of several other physical models, including optimal paths under strong disorder, disordered polymers, watersheds and optimal path cracks on uncorrelated substrates, hulls of explosive percolation clusters, and strands of invasion percolation fronts. Moreover, we find that the fractal dimension of the largest fracture under extreme disorder, $d_f=1.86 \pm 0.01$, is outside the statistical error bar of standard percolation. This discrepancy is due to the appearance of trapped regions or cavities of all sizes that remain intact till the entire collapse of the fuse network, but are always accessible in the case of standard percolation. Finally, we quantify the role of disorder on the structure of the largest cluster, as well as on the backbone of the fracture, in terms of a distinctive transition from weak to strong disorder characterized by a new crossover exponent.Comment: 5 pages, 4 figure

Back to replacement migration: a new European perspective applying the prospective-age concept

Background: The UN Replacement Migration report (2000) had a significant impact in academic and civil society. Its approach consisted of estimating the migration volumes required to mitigate the effects of population decline and ageing. The volume of migrants required to prevent population decline and sustain the working-age population was not particularly high, but the vast number of migrants needed to maintain the potential support ratio was highlighted as an unrealistic goal. Objective: In this paper the UN exercise is revisited and updated by deploying the concept of prospective age to overcome a strict chronological definition of the working-age population. The replacement migration approach is developed from a new European perspective, the temporal series is extended for an additional decade, and alternative operative age-group definitions are compared by projecting replacement migration estimations according to both classic (conventional) and dynamic (prospective) age limits. Conclusions: The key conclusions of the original UN publication are reasserted. In many countries the replacement migration volumes needed to sustain the decline in total population and working-age population are of an order of magnitude similar to recent observed migration. However, even under the prospective-age approach the halt of the ageing process – expressed as the maintenance of the current potential support ratio – remains an unrealistic target. Contribution: We propose the deployment of the prospective-age concept to define dynamic age limits in the definition of working-age population. Because the prospective-age concept is flexible it will be possible to explore other dimensions from this perspective in the future, increasing the analytical potential of replacement migration estimations as a valuable contribution to the demographic ageing debate.info:eu-repo/semantics/publishedVersio

Kinetics of TNF-alpha and IFN-gamma mRNA expression in islets and spleen of NOD mice

Insulin-dependent diabetes mellitus is caused by autoimmune destruction of pancreatic ß cells. Non-obese diabetic (NOD) mice spontaneously develop diabetes similar to the human disease. Cytokines produced by islet-infiltrating mononuclear cells may be directly cytotoxic and can be involved in islet destruction coordinated by CD4+ and CD8+ cells. We utilized a semiquantitative RT-PCR assay to analyze in vitro the mRNA expression of TNF-alpha and IFN-gamma cytokine genes in isolated islets (N = 100) and spleen cells (5 x 10(5) cells) from female NOD mice during the development of diabetes and from female CBA-j mice as a related control strain that does not develop diabetes. Cytokine mRNAs were measured at 2, 4, 8, 14 and 28 weeks of age from the onset of insulitis to the development of overt diabetes. An increase in IFN-gamma expression in islets was observed for females aged 28 weeks (149 ± 29 arbitrary units (AU), P<0.05, Student t-test) with advanced destructive insulitis when compared with CBA-j mice, while TNF-alpha was expressed in both NOD and CBA-j female islets at the same level at all ages studied. In contrast, TNF-alpha in spleen was expressed at higher levels in NOD females at 14 weeks (99 ± 8 AU, P<0.05) and 28 weeks (144 ± 17 AU, P<0.05) of age when compared to CBA-j mice. The data suggest that IFN-gamma and TNF-alpha expression in pancreatic islets of female NOD mice is associated with ß cell destruction and overt diabetes.1347135

Predictive equations of pulmonar function for healthy children in Portugal

[resumo][abstract

Danos provicados por Cebus nigritus (Goldfuss, 1809) a plantios de Pinus taeda L: frequência e perdas de incremento.

Resumo

Electrochemical miRNA-34a-based biosensor for the diagnosis of Alzheimer’s disease

Alzheimer's disease (AD) is the most common dementia type and a leading cause of death and disability in the elderly. Diagnosis is expensive and invasive, urging the development of new, affordable, and less invasive diagnostic tools. The identification of changes in the expression of non-coding RNAs prompts the development of diagnostic tools to detect disease-specific blood biomarkers. Building on this idea, this work reports a novel electrochemical microRNA (miRNA) biosensor for the diagnosis of AD, based on carbon screen-printed electrodes (C-SPEs) modified with two gold nanostructures and a complementary anti-miR-34a oligonucleotide probe. This biosensor showed good target affinity, reflected on a 100 pM to 1 M linearity range and a limit of detection (LOD) of 39 pM in buffer and 94 aM in serum. Moreover, the biosensors response was not affected by serum compounds, indicating selectivity for miR-34a. The biosensor also detected miR-34a in the cell culture medium of a common AD model, stimulated with a neurotoxin to increase miR-34a secretion. Overall, the proposed biosensor makes a solid case for the introduction of a novel, inexpensive, and minimally invasive tool for the early diagnosis of AD, based on the detection of a circulating miRNA overexpressed in this pathology.This work was supported by 0624_2IQBIONEURO_6_E, 2IQBioneuro, Promotion of an R&I network in biological chemistry for the diagnosis and treatment of neurological diseases EP-INTERREG V Spain Portugal (POCTEP), and by Portuguese funds through FCT in the framework of the project PTDC/BTM-MAT/4156/2021. S.D.S acknowledges FCT (Fundação para a Ciência e a Tecnologia, I.P.) for her contract under the Norma Transitória – DL57/2016/CP/CP1360/CT0013.info:eu-repo/semantics/publishedVersio