Over the last decades, linear models have been studied by the scientific community as an important tool of statistical modelling in a great variety of phenomena. However, in many situations the data are grouped according to factors, so the introduction of random effects is required in order to consider the correlation between observations from the same individual, in which case linear mixed models are used. In addition, it is often observed that the data comes from a heterogeneous population, giving rise to situations where the estimation of a single linear model is not sufficient. Therefore, it is necessary to use models that incorporate this unobserved heterogeneity, as is the case of mixture models. Thus, mixtures of linear mixed models allow modelling the heterogeneity among the individuals and, at the same time, to account for correlations between observations from the same individual. Choosing the number of components for mixture models has long been considered as an important but difficult research problem. There is wide variety of literature available on the performance of model selection statistics for determining the number of components in mixture models. In this article, we study the problem of determining the number of components in mixtures of linear mixed models, investigating the performance of various model selection methods. In order to evaluate the methodologies developed, we carry out a simulation study and we illustrate these methodologies using a real data set. | The research of L. Novais was financed by FCT - Fundação para a Ciência e a Tecnologia, through the PhD scholarship with reference SFRH/BD/139121/2018. This work was supported by the strategic programme UID/BIA/04050/2019 funded by national funds through the FCT.IP.

Aspects of the reproductive biology of snapping shrimp Alpheus euphrosyne euphrosyne inhabiting a tropical estuary were studied between August 2007 and July 2008 by examining 1309 females of 8.5–21.5 mm carapace length. Although the occurrence of ovigerous females was noted from October, the main breeding season extended from January to March. Size at 50% sexual maturity was estimated as 10.6±1.40 mm CL. Number of eggs per brood ranged from 141 to 1553 in females of 11.2 to 19.2 mm CL and mean absolute fecundity was estimated as 480±272 eggs. Regressions of log egg number on log total length, log carapace length and log weight revealed isometric relationships (p <0.01). Results of ANOVA revealed significant variation between mean short and long axes of eggs among five embryo developmental stages (P <0.05). The estimated egg batch 33 volume ranged from 4.99 to 32.09 mm3 with a mean of 12.44 mm3. Estimates of reproductive output from 41 females ranged between 8.21 to 31.25% with a mean value of 18.55±5.81.

ARTICLE IN PRESS | Although a number of studies have indicated that microbes are key players in nutrient cycling, limitations on how to accurately assess their diversity have constrained further knowledge on the role of microbial diversity in organic matter decomposition in streams. Microbial diversity on leaf litter of Alnus glutinosa was assessed by microscopic analysis of bacterial cells and released fungal conidia, and by the number of operational taxonomic units (OTUs) from denaturing gradient gel electrophoresis using two different primer pairs targeting the rDNA of fungi (ITS2 and 5' end of the 18S region) and bacteria (V3 region and V6-V8 regions). Fingerprints of fungal and bacterial DNA showed a higher diverse microbial community on decomposing leaves than that assessed by microscopy-based techniques. Higher number of OTUs was obtained with primers targeting the ITS2 region of fungi, but the selected primers for bacteria showed similar number of OTUs. A succession of fungal or bacterial taxa throughout leaf decomposition was found, regardless of the chosen primer. These microbial communities ensured a rapid decomposition of submerged leaf litter (k = -0.045 day(-1)). Fungal biomass (up to 58 mg g(-1) AFDM) contributed with more than 98% to the total microbial biomass, supporting a greater role of fungi than bacteria in leaf-litter decomposition in streams. (C) 2009 Elsevier GmbH. All rights reserved. | - (undefined)

First published: 07 August 2022 | [Excerpt] In a sense, a single individual host can be considered an ecosystem. For example, a host may be seen as an environment that can be colonized by a high diversity of entities such as different mutualists, commensals, and parasites. | Ministry of Science and Higher Education of the Russian Federation, Grant/Award Number: FUUW-2022-0039; Russian Scientific Foundation, Grant/Award Number: 21-14-00092

Wood combustion experiments were carried out to determine the effect of ignition technique, biomass load and cleavage, as well as secondary air supply, on carbon monoxide (CO), total hydrocarbon (THC), particulate matter (PM10) and particle number emissions fromawoodstove.Wood fromtwo typical tree species in the Iberian Peninsula was selected: pine (Pinus pinaster) and beech (Fagus sylvatica). The highest CO and total hydrocarbon emission factors (EFs) were observed, respectively, for pine and beech, for high and low fuel loads. The highest PM10 EFwas recorded for the operationwith lowloads for bothwoods. Secondary air supply produced the lowest PM10 emission factors. The top ignition can decrease the PM10 EF to less than halfwhen compared with the common technique of lighting from the bottom. The lowest particle number emission factors were observed when operating with high loads of split beech logs and when using secondary air supply during the combustion of pine. Regarding particle number distributions, the highest geometric mean diameter (Dg), for both woods, were observed when operating with high loads (with split and non-split wood).

Aeromonas molluscorum Av27 cells were exposed to 0, 5 and 50 mM of TBT and the respective transcriptomes were obtained by pyrosequencing. Gene Ontology revealed that exposure to 5 mM TBT results in a higher number of repressed genes in contrast with 50 mM of TBT, where the number of overexpressed genes is greater. At both TBT concentrations, higher variations in gene expression were found in the functional categories associated with enzymatic activities, transport/binding and oxidationreduction. A number of proteins are affected by TBT, such as the acriflavin resistance protein, several transcription-related proteins, several Hsps, ABC transporters, CorA and ZntB and other outer membrane efflux proteins, all of these involved in cellular metabolic processes, important to maintain overall cell viability. Using the STRING tool, several proteins with unknown function were related with others involved in degradation processes, such as the pyoverdine chromophore biosynthetic protein, that has been described as playing a role in the SneC cleavage of organotins. This approach has allowed a better understanding of the molecular effects of exposure of bacterial cells to TBT. Furthermore it contributes to the knowledge of the functional genomic aspects of bacteria exposed to this pollutant. Furthermore, the transcriptomic data gathered, and now publically available, constitute a valuable resource for comparative genome analysis.

Photodynamic inactivation of bioluminescent Escherichia coli in the presence of cationic chlorin and isobacteriochlorin photosensitizers (PSs) obtained from 5,10,15,20-tetrakis(pentafluorophenyl)-porphyrin is described. The spectroscopic data for the neutral and cationic derivatives and their photophysical characterizations, especially fluorescence and singlet oxygen generation capacity are also reported. The results show that there is a direct relation between the inactivation efficiency and the increasing number of charges on the molecules. The combined effect of higher wavelength absorption and number of positive charges on the PS shows a 6.1 log reduction during the inactivation process. Overall this study shows that the cationic isobacteriochlorin has high potential to be used as PS for the inactivation of Gram (-) bacteria.

This article reviews fish consumption data, mercury tolerable intake values, and mercury (Hg) content in fish, based on several reports from the Food and Agriculture Organization and European Union. The study assumptions are valid based on the current established USEPA reference dose (RfD). Combining the number of meals (per week), amount of fish ingested (by meal), and levels of MeHg in fish, this study calculates and presents isocurves indicating the maximum number of fishmeal per week without exceeding the USEPA RfD for methylmercury (MeHg). RfD are assumed to be the Bexposure dose that is likely to be without deleterious effect even if continued exposure occurs over a lifetime.^ The study points out that even considering a single 50-g fish meal per week, the USEPA RfD would be exceeded, triggered by values above 0.84 μg g−1 of MeHg in fish, and this despite being allowed levels up to 1.0 μg g−1 of MeHg in fish consumption!—Have we a health risk? Fish consumption is expected to be relatively stable, while anthropogenic mercury emissions are expected to stabilize or even to increase beyond current values. How many meals of fish per week can we have, combining the number of fish meals per week, amount of fish ingested by meal, and levels of MeHg in fish?

Effect assessment is usually based on responses obtained from standard tests, in which organisms are well fed and in an optimal population density. For a more thorough assessment of ecotoxicological risk, information is needed for chemical effects in systems that closer reflect the potential exposure in the field systems. Responses measured in standard density experiments do not fully reflect the field scenario, where populations' size fluctuate with environmental conditions, leading to very low organism number in certain season/conditions and high number in others. In the present study, the possible interaction between density and Cu-pollution was investigated in regard to population growth, using Enchytraeus crypticus, and for individual juvenile growth, using Eisenia fetida. The standardized ISO and OECD guidelines for enchytraeids and earthworms were adapted to test four densities and four Cu concentrations. The final population number was used to assess the effects and possible interaction between densities and Cu toxicity for population responses and the increase in individual organism wet weight was used as growth response. The study showed that although initial density itself had tremendous impact on population and individual growth, organisms under different densities had the same sensitivity to Cu. (C) 2011 Elsevier B.V. All rights reserved.

To assess micromixing in T-jet mixers, having various geometries and flow rates, a set of test reactions was employed. This consisted of the reactions between 1-naphthol/2-naphthol and diazotized sulfanilic acid in aqueous solution. The results showed that the Reynolds number has a large effect on the rate of mixing. Furthermore, the geometrical parameters also influenced the product distribution of the test reactions. Increasing the ratio between the mixing chamber width and the inlet jet width improved mixing. Shallow chambers can show poorer mixing while increasing the depth enhances both mixing and reactor capacity. A characteristic mixing time was defined and determined as a function of Reynolds number in the range 300-3000 for the various reactor geometries. The effects of chamber width and depth as well as of jet width on product distributions and mixing times were related to the flow regimes found earlier by Planar Laser Induced Fluorescence.