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AbstractIn this work, the mechanical response of an one-dimensional active solid—defined as a network of active stochastic particles interacting by nonlinear hard springs— subject to an external deformation force, is numerically studied and rationalized with a minimal model. It is found that an active solid made of linear springs and subject to an external stress presents an average deformation which is independent of the system’s activity. However, when the active solid is made of nonlinear hard springs, the solid’s average deformation decreases with respect to a passive system under the same conditions, and as a function of activity and rotational noise in the system. The latter result may shed light on new ways to creating an active metamaterial, which could tune its stiffness by moving either its activity or rotational noise.Graphical abstract

Over half of the world's arable land is acidic, which constrains cereal production. In South America, different rice-growing regions (Cerrado in Brazil and Llanos in Colombia and Venezuela) are particularly affected due to high aluminum toxicity levels. For this reason, efforts have been made to breed for tolerance to aluminum toxicity using synthetic populations. The breeding program of CIAT-CIRAD is a good example of the use of recurrent selection to increase productivity for the Llanos in Colombia. In this study, we evaluated the performance of genomic prediction models to optimize the breeding scheme by hastening the development of an improved synthetic population and elite lines. We characterized 334 families at the S0:4 generation in two conditions. One condition was the control, managed with liming, while the other had high aluminum toxicity. Four traits were considered: days to flowering (FL), plant height (PH), grain yield (YLD), and zinc concentration in the polished grain (ZN). The population presented a high tolerance to aluminum toxicity, with more than 72% of the families showing a higher yield under aluminum conditions. The performance of the families under the aluminum toxicity condition was predicted using four different models: a single-environment model and three multi-environment models. The multi-environment models differed in the way they integrated genotype-by-environment interactions. The best predictive abilities were achieved using multi-environment models: 0.67 for FL, 0.60 for PH, 0.53 for YLD, and 0.65 for ZN. The gain of multi-environment over single-environment models ranged from 71% for YLD to 430% for FL. The selection of the best-performing families based on multi-trait indices, including the four traits mentioned above, facilitated the identification of suitable families for recombination. This information will be used to develop a new cycle of recurrent selection through genomic selection.

In this work, we propose to approximate the Gaussian integral, the error function and the cumulative distribution function by using the power series extender method (PSEM). The approximations proposed in this paper present a high accuracy for the complete domain [–∞,∞]. Furthermore, the approximations are handy and easy computable, avoiding the application of special numerical algorithms. In order to show its high accuracy, three case studies are presented with applications to science and engineering.

To our knowledge, there are no studies about the structure and ecological function of extrafloral nectaries (EFNs) in Opuntia robusta. This is the first description of EFNs in O. robusta, where young spines have an interesting structure and a secreting function, which are different from EFNs described in other Cactaceae species. We used light, scanning-electron, and transmission-electron microscopy to examine morphology, anatomy, and ultrastructure of the secretory spines in areoles in female and hermaphrodite individuals of O. robusta. Young cladodes develop areoles with modified and secretory spines as EFNs only active during the early growth phase. EFNs are non-vascularized structures, with no stomata, that consist of a basal meristematic tissue, a middle elongation region, and an apical secretory cone formed by large globular epidermal cells, containing nectar and medullar elongated cells. We observed the presence of Golgi apparatus, vesicles and plastids in the medullar and sup-epidermal cells of the spine. We propose that the nectar is stored in the globular cells at the apex of the spine and secreted by breaking through the globular cells or by pores. We recorded a more frequent presence of ants on younger cladode sprouts producing young secreting spines: this result is parallel with the predictions of Optimal Defense Hypothesis, which states that younger plant organs should be better defended than older ones because their loss produces a higher fitness impairment. Although Diaz-Castelazo's hypothesis states that a more complex structure of EFNs correlates with their lower among-organs dispersion, comparing to less complex EFNs, non-vascularized structure of EFNs in O. robusta is not associated with their higher among-organs dispersion likened to O. stricta, which produces vascularized EFNs. We provide evidence that this characteristic is not a good taxonomic feature of Opuntia genus. Moreover, the comparison of EFNs of O. robusta and O. stricta suggests that the hypothesis of Diaz-Castelazo should be revised: it is rather a rule but not a law.

Genome erosion is a frequently observed result of relaxed selection in insect nutritional symbionts, but it has rarely been studied in defensive mutualisms. Solitary beewolf wasps harbor an actinobacterial symbiont of the genus Streptomyces that provides protection to the developing offspring against pathogenic microorganisms. Here, we characterized the genomic architecture and functional gene content of this culturable symbiont using genomics, transcriptomics, and proteomics in combination with in vitro assays. Despite retaining a large linear chromosome (7.3 Mb), the wasp symbiont accumulated frameshift mutations in more than a third of its protein-coding genes, indicative of incipient genome erosion. Although many of the frameshifted genes were still expressed, the encoded proteins were not detected, indicating post-transcriptional regulation. Most pseudogenization events affected accessory genes, regulators, and transporters, but “Streptomyces philanthi” also experienced mutations in central metabolic pathways, resulting in auxotrophies for biotin, proline, and arginine that were confirmed experimentally in axenic culture. In contrast to the strong A+T bias in the genomes of most obligate symbionts, we observed a significant G+C enrichment in regions likely experiencing reduced selection. Differential expression analyses revealed that—compared to in vitro symbiont cultures—“S. philanthi” in beewolf antennae showed overexpression of genes for antibiotic biosynthesis, the uptake of host-provided nutrients and the metabolism of building blocks required for antibiotic production. Our results show unusual traits in the early stage of genome erosion in a defensive symbiont and suggest tight integration of host–symbiont metabolic pathways that effectively grants the host control over the antimicrobial activity of its bacterial partner.

Stegomyia aegypti (Linnaeus, 1762) vectors arboviruses of public health concern in urban areas of tropical countries, so it is necessary to reduce its population. Among the control methods used, chemically synthesized molecules have been widely employed, nonetheless, the over usage of the same mechanism of action can result in the resistance selection. Considering the influence of insect resistance with the success of chemical control of vectors, this study aims to assess the susceptibility to organophosphorus of a population of 5. aegypti from Paranaguá (Paraná, Brazil), after intense use of malathion during a dengue outbreak. World Health Organization susceptibility tests and expression of Acetylcholinesterase ace-1, cytochrome P450 monooxygenase CYP6N12, and α-esterases CCEae3A genes were evaluated. The mortality rate of wild females (66.5%) indicated their resistance status, furthermore, a new discriminant concentration was detected in this population (3.41%). Exclusively CYP6N12 gene was overexpressed in malathion-resistant females indicating its possible contribution to the transformation of this insecticide. Constant monitoring of insecticide resistance of current and past molecules, mainly in port areas where there is a large flow of species, is crucial for effective use of insecticide in vector control programs.

In the field of applied sciences, systems are frequently modeled using mathematical frameworks that include systems of nonlinear algebraic equations. Identifying their roots, whether real or complex, is of critical importance. The widespread use of complex numbers in science and engineering highlights the importance of accurately determining the complex roots of equations. This article presents a study in which the complex roots of a system of equations are identified through an approach that utilizes homotopy continuation, with the curve being traced using a hyperspherical path tracking technique. Furthermore, this article details five case studies on electrical networks where this method is applied to solve systems of equations containing imaginary coefficients to find mesh currents. The path tracking shows the behavior of system equation in each case study. Finally, an analysis of the precision of the solutions obtained in these case studies is provided, demonstrating an accuracy of up to 15 SDs in a single iteration during the refinement stage.

The western margin of the Andes Mountains often experiences large earthquakes, but the potential size of earthquakes along the eastern margin is unknown. Analysis of GPS data shows that a substantial section of the eastern margin is locked and could rupture in an earthquake with a magnitude of up to 8.9. Subduction of the Nazca plate beneath South America has driven the growth of the Andes Mountains. Subduction has routinely generated earthquakes larger than magnitude 8.0 along the western margin of the mountain belt 1 , but the potential size of less frequent earthquakes in the eastern, backarc margin is unknown. Continued support of the high Andean Plateau at the centre of the Andes can be explained only if deformation of the backarc margin is ongoing 2 , 3 , 4 . Here we present GPS data that record surface motions in the Subandean ranges that are part of the backarc margin. We find that the velocity of surface movement decreases sharply from west to east across the Subandean ranges. We suggest that a subhorizontal fault underlying the ranges slips freely at depth in the west, but is locked for up to 100 km in shallower sections further east. Analysis of fault scarps formed where the subhorizontal fault intersects the surface indicates that the fault has generated repeated large earthquakes. We suggest that rupture of the entire locked section of the fault could generate an earthquake of magnitude 8.7–8.9. We attribute the large seismic potential to the unusual width of the Subandean ranges, and suggest that deformation of the Subandean ranges, at a rate unmatched by erosion, causes the mountain range to widen.

High environmental temperatures cause heat stress in ewes, resulting in thermoregulatory problems. In this study, the thermoregulatory responses of Blackbelly adult ewes (G1, n = 14) and female lambs (G2, n = 7), during the summer under tropical conditions, in southern Mexico were analyzed. Different physiological variables and skin temperatures (ST) of the ewes were recorded. Breathing frequency (BF) values were similar between groups at 116.73 ± 33.598 bpm (G1) and 113.661 ± 34.515 bpm (G2) (p > 0.05). In the case of skin elasticity (SE), there were no significant differences between the time of day and the age of the ewes (p > 0.05). Significant differences were observed between groups for BF, rectal temperature (RT), and heart rate (HR) values (p < 0.05). All ST values, for both groups, were significantly higher during the afternoon (p < 0.001). In general, all Blackbelly adult ewes and female lambs during the summer present severe heat stress conditions as a result of an increase in physiological constants and ST. It is concluded that all ewes thermoregulate body temperature by modifying different physiological variables to counteract the effect of heat stress.

In this paper, we present modified homotopy perturbation method coupled by Laplace transform to solve non-linear problems. As case study modified homotopy perturbation method coupled by Laplace transform is employed in order to obtain an approximate solution for the non-linear differential equation that describes the steady-state of a heat 1-D flow. The comparison between approximate and exact solutions shows the practical potentiality of the method. nema