A new approach to detectability of discrete-time infinite Markov jump linear systems

This paper deals with detectability for the class of discrete-time Markov jump linear systems (MJLS) with the underlying Markov chain having countably infinite state space. The formulation here relates the convergence of the output with that of the state variables, and due to the rather general setting, a novel point of view toward detectability is required. Our approach introduces invariant subspaces for the autonomous system and exhibits the role that they play. This allows us to show that detectability can be written equivalently in term of two conditions: stability of the autonomous system in a certain invariant space and convergence of general state trajectories to this invariant space under convergence of input and output variables. This, in turn, provides the tools to show that detectability here generalizes uniform observability ideas as well as previous detectability notions for MJLS with finite state Markov chain, and allows us to solve the jump-linear-quadratic control problem. In addition, it is shown for the MJLS with finite Markov state that the second condition is redundant and that detectability retrieves previously well-known concepts in their respective scenarios. Illustrative examples are included.4362132215

Antiophidian properties of plant extracts against Lachesis muta venom

Snakebites comprise a serious health problem in several countries due to their global incidence, which exceeds 2.5 million per year, and the elevated number of victim fatalities. To counteract envenomations, antivenoms have been used regularly for more than a century. Apart from side effects including anaphylactic reactions, antivenoms are not able to efficiently neutralize local tissue damage, which contributes to increasing the severity and morbidity observed in patients. This fact, in turn, may be responsible for economic hardship, particularly in rural populations of developing countries. In the present work, we evaluated the antiophidian properties of 12 Brazilian plant extracts against the hemolytic, coagulant, hemorrhagic and proteolytic effects of Lachesis muta venom. Taken together, our data revealed that most of these aqueous products were capable of inhibiting those activities at different levels, except for Sapindus saponaria extract. In contrast, Stryphnodendron barbatiman extract completely neutralized all the analyzed biological activities. Thus, we may conclude that Brazilian flora may also be useful against L. muta accidents.(FAPERJ) Fundacao de Amparo a Pesquisa do Estado do Rio de JaneiroFAPESPCNPqCoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)International Foundation for Science (IFS, Sweden

High Levels of Heavy Metal(loid)s Related to Biliary Hyperplasia in Hedgehogs (Erinaceus europaeus)

Simple Summary Heavy metal(loid)s are hazardous substances for humans, animals and ecosystems. The liver is one of the most affected organs, presenting lesions after being acutely or chronically exposed to these substances. In this study, hepatic metal(loid)s' concentrations were associated with biliary hyperplasia, which was the most common hepatic lesion found in a group of western-European hedgehogs from rescue centres in Portugal. With exception of arsenic (As), all metal(loid)s were present in higher concentrations in animals with biliary hyperplasia. Further research is necessary to support these results and clarify the molecular mechanisms that lead to hepatic lesions provoked by these compounds. Heavy metal(loid) pollution of ecosystems is a current One Health problem. The liver is one of the most affected organs in cases of acute or chronic exposure to abnormal amounts of these substances, inducing histopathologic lesions. In order to assess the influence of heavy metal(loids), forty-five European hedgehogs (Erinaceus europaeus) were submitted to necropsy, and liver samples were collected for a routine histopathology exam and metal(loid)s determination (As, Cd, Co, Cr, Cu and Pb) by ICP-MS. Age was estimated during the necropsy exam. Biliary hyperplasia was the most frequent lesion observed (16/45; 35.56%). No statistically significant associations were found between biliary hyperplasia and age or sex. Metal(loid)s' concentrations were higher in animals with biliary hyperplasia (except for As). There was a statistically significant difference for both Cd and Co. For As, Cd and Co, cubs and juveniles animals showed significantly lower concentrations than elder individuals. Only for Pb were significant differences found between females and males. As described in the literature, exposure to metal(loid)s may be a cause of biliary hyperplasia, although further research (including the use of biochemical methods) is needed to support these results. To the authors' knowledge, this is the first report of this association in hedgehogs.This work was supported by National Funds by the Portuguese Foundation for Science and Technology (FCT). The authors of the research unit CITAB (CJB and PAO) received funding from FCT-reference of the project: UIDB/04033/2020. The author of the research unit CECAV (FS) received funding from FCT-reference of the project: UIDB/CVT/00772/2020. CJB was supported by FCT due to the phD scholarship 2021.04520.BD. TLM was supported by UIDB/CVT/00772/2020 and LA/P/0059/2020 funded by FCT

Impacts of invasive ants on pollination of native plants are similar in invaded and restored plant communities

This is the final version. Available on open access from Elsevier via the DOI in this recordData availability: Data will be made available on request.Ants are amongst the most successful invaders worldwide and can markedly modify invaded communities through biotic interactions. Invasive ants, for example, can compete with native pollinators for resources, act as legitimate pollinators, or disrupt plant-pollinator mutualistic interactions, thereby affecting native plant reproduction. Ecological restoration aims to mitigate the impact of invasive species and restore ecological communities and ecosystem functioning. Here we investigated the combined effects of two invasive ant species, the yellow crazy ant (Anoplolepis gracilipes) and white-footed ant (Technomyrmex albipes), on the pollination and reproduction of native plants in the context of a large-scale plant community restoration experiment. We conducted ant exclusion experiments and pollinator observations to obtain data on plant reproduction and pollination of four plant species. The experiments were conducted across eight granitic inselbergs on the island of Mahé, Seychelles, four of which are undergoing restoration since 2011 and four remained as invaded control sites (unrestored). Our findings indicate that native plants on Seychelles’ inselbergs relied primarily on flying flower visitors for pollination, considering that the contribution of ants to fruit set was generally small and substantially lower than that of flying pollinators. Moreover, while flying pollinators approached flowering plants irrespective of invasive ant presence, the number of probed flowers per visit was reduced, in both restored and unrestored communities. Therefore, native plant reproduction was negatively affected by the presence of invasive ants and this effect was similar in restored and unrestored plant communities. Our research suggests that invasive ants may contribute to changes in plant communities by deterring legitimate pollinators of native plants, an impact that is unlikely to be alleviated through early stages of ecological restoration.Deutsche Forschungsgemeinschaft (DFG)Portuguese Foundation for Science and Technolog

Feature selection in the reconstruction of complex network representations of spectral data

Complex networks have been extensively used in the last decade to characterize and analyze complex systems, and they have been recently proposed as a novel instrument for the analysis of spectra extracted from biological samples. Yet, the high number of measurements composing spectra, and the consequent high computational cost, make a direct network analysis unfeasible. We here present a comparative analysis of three customary feature selection algorithms, including the binning of spectral data and the use of information theory metrics. Such algorithms are compared by assessing the score obtained in a classification task, where healthy subjects and people suffering from different types of cancers should be discriminated. Results indicate that a feature selection strategy based on Mutual Information outperforms the more classical data binning, while allowing a reduction of the dimensionality of the data set in two orders of magnitud