The response of chironomid assemblages to mineral richness gradient in the Western Carpathian helocrenes

We investigated the effect of water mineral richness (basicity) on chironomid assemblages of helocrene springs in the Western Carpathians. To do so, we tested for relationships between the taxonomic structure, total abundance and abundance of most frequent taxa of chironomid assemblages and mineral richness gradient in two contrasting habitats: trickle (A) and water-loged soil with standing water (B). Chironomid assemblage showed a strong and systematic response to the complex gradient of mineral richness, which explained the largest portion of variance in both the habitat A and B faunal data and was projected on the first axes of NMDS ordinations. As only 17 samples were analysed so far, the results are considered preliminary and, hopefully, more confident results will be available in near future

The Chironomidae of the Western Carpathian helocrenes: Metacommunity structuring and its drivers in unique habitats

Springs are unique and vulnerable habitats, which have always been rather out of focus of the scientist interest. Nevertheless, they frequently host very diverse and species-rich assemblages with high proportion of species more or less adapted to their unique environment and can act as biodiversity hotspots in some areas. The Western Carpathian springs are helocrene springs and represent wide variety of different habitat types, from mineral rich sparsely-vegetated or bryophytes-rich covered helocrenes to acidic peaty sites. Such diversification allows the creation of highly diverse assemblages, in which Chironomidae usually dominate in both species richness and abundance. The aim of this study was to provide a comprehensive overview of chironomid assemblages inhabiting the unique environment of spring fens and factors driving the metacommunity structuring and populations of individual taxa. We examined chironomid assemblages of 62 small, treeless helocrenes sites, which are highly isolated from each other by the terrestrial environment constituting dispersal barriers such as the east-west oriented mountain ridges and valleys. The sampling was performed to cover mesohabitat heterogeneity of study sites. Two main mesohabitats were sampled, the plot with flowing water and coarser substratum near water source (the lotic mesohabitat), and water-logged soil with standing water (the lentic mesohabitat). Study sites hosted nearly 100 chironomid taxa, both mesohabitats were inhabited by chironomid assemblages similar in number of species and abundances and the local environment was proved to be the main driver of compositional changes in chironomid assemblages as expected. Moreover, the significant spatial structure of assemblages was found at the lentic mesohabitat, while biotic interactions described by the abundance of Gammarus fossarum and taxa richness and abundances of predators did not significantly contribute to compositional changes in assemblages at any mesohabitat. Nevertheless, taxa-specific responses revealed populations of many taxa significantly affected by biotic interactions, especially at the more stable lotic mesohabitat, which is in concordance with suggested greater importance of biotic interactions at stable environment. Our results emphasized the importance of multilevel approach in community ecology for proper distinction between different mechanisms of metacommunity structuring. Biotic interaction such as competition can result into the same community patterns as environmental filtering, thus the involvement of detailed analyses of species requirements and interactions is necessary

IDENTIFICATION OF CYCLE-TO-CYCLE VARIABILITY SOURCES IN SI ICE BASED ON CFD MODELING

The presented paper deals with modelling of cycle‐to‐cycle variations (CCV) in SI ICEs by means of 3‐D CFD LES approach. The main goals are the following: to identify the most important sources of CCV and to compare 2 different ignition systems: classical spark ignition and turbulent flame jet. Calibrated 3‐D CFD LES models of these engines are applied to perform time‐demanding multi‐cycle calculations of selected engine operating points. The simulation data are analyzed including comparison with experimental data and main conclusions are drawn. The turbulence, which is generated during intake stroke, is identified as the main CCV source while early flame kernel development (strongly influenced by local turbulence) is also important.Tento článek se zabývá modelováním mezicyklové variability v zážehových spalovacích motorech pomocí 3‐D CFD LES přístupu. Hlavní cíle práce jsou následující: identifikace hlavních zdrojů mezicyklové variability a porovnání 2 různých systémů pro zapálení směsi: klasický zážeh pomocí svíčky a turbulentní hořící paprsek. Kalibrované 3‐D CFD LES modely těchto motorů jsou použity pro časově náročné simulace mnoha po sobě následujících cyklů pro vybrané pracovní body těchto motorů. Data ze simulací jsou analyzována včetně srovnání s experimenty a jsou formulovány hlavní závěry. Turbulence, která je primárně generována během sacího zdvihu, je identifikována jako hlavní zdroj mezicyklové variability, zatímco co úvodní fáze vývinu jádra plemene (silně ovlivněna lokální turbulencí) je taky důležitá

New chironomid pupal types from Norway, one with a male pharate adult: Pseudosmittia paraspinispinata n.sp.

Three new pupal types from Norway are described, one with an associated male: Pseudosmittia parspinispinata n.sp

Patterns of bryophyte and vascular plant richness in European subalpine springs

The diversity of spring habitats can be determined not only by local environmental conditions, but also by large-scale biogeographical effects. The effects can differ across various groups of organisms. We compared α-, β- and γ-diversity patterns of bryophytes and vascular plants of (sub)alpine springs in three contrasting mountain ranges: Alps (Switzerland), Balkans (Bulgaria), Western Carpathians (Slovakia, Poland). We used univariate and multivariate statistics to test for the effects of pH, conductivity, altitude, slope, mean annual temperature and annual precipitation on diversity patterns of both taxonomic groups and compared diversity patterns among the regions for particular pH and conductivity classes. We identified acidophyte and basiphyte, calcifuge and calcicole species using species response modelling. All regions displayed significant relationship between conductivity and α-diversity of vascular plants. Bulgaria showed the highest α-diversity of vascular plants for the middle part of the conductivity gradient. For both taxonomic groups, the β-diversity in the middle part of gradient was highest in Swiss Alps. The total species pool was lowest in Bulgaria. The percentage of basiphyte and calcicole species was highest in the Alps. In (sub)alpine springs, mineral richness was a better determinant of vascular plant α-diversity than pH, and the extent of the alpine area did not coincide with α-diversity. Observed inter-regional differences in diversity patterns could be explained by the different proportion of limestone bedrock and different biogeographic history. The differences in α-diversity between both taxonomic groups are presumably result of the different rates of adaptation processe

APPLICATION OF ADVANCED COMBUSTION MODELS IN INTERNAL COMBUSTION ENGINES BASED ON 3-D CFD LES APPROACH

This paper deals with the application of advanced simulation techniques for combustion modeling in the case of an internal combustion engine. The main focus is put on models with a high predictive ability hence 3-D CFD was selected while using LES (turbulence model) and detailed chemistry (both SI and CI ICE) or turbulent flame propagation (SI ICE). Both engine types are considered – spark ignited ICE and a compression ignited engine. Examples are shown and comparison with available experimental data is presented. The main conclusion is that such models are capable of high quality predictions while very little tuning is needed. This is desired as such models could be applied in the early phases of ICE development. On the other hand, such calculations are very demanding in terms of computational power

Recognition of stream drying based on benthic macroinvertebrates: a new tool in Central Europe

Many streams in the extensive Central European region have an intermittent flow regime. Conventional hydrological methods used to identify zero-flow conditions, and in particular drying events, have limited use when assessing large areas dominated by low-order streams. We developed a novel multimetric index to recognise antecedent stream drying based on the analysis of benthic macroinvertebrate communities. The data used to develop the index were collected in pristine streams with different flow permanence regimes between 2012 and 2014, using standard sampling methods for ecological status assessment. The data include 64 perennial, 19 near-perennial and 27 intermittent benthic macroinvertebrate samples. Metrics considered for the index included variables based on (i) the occurrence of indicator taxa, (ii) the proportion of biological and ecological traits, and (iii) structural community metrics. Linear discriminant analysis identified the metric combinations that best discriminated among the three flow permanence categories. Different metrics were used in the final multimetric index calculation for the autumn and spring season that followed stream drying. In both seasons, the index included the proportion of indicator taxa and the proportion of taxa with high body flexibility. In addition, the autumn index included the proportion of taxa with a preference for organic substrates, whereas in spring the index included total abundance. Independent data from regulatory monitoring activity were used to validate the accuracy of the index. The correct classification of independent samples was 92% and 96% for samples from perennial and non-perennial sites, respectively. The index can be calculated using data collected by routine monitoring programmes used to assess ecological status and provides information about stream intermittence where conventional hydrological monitoring is limited. As intermittent streams increase in extent in global regions including Central Europe, the tool may be of particular interest to those who use invertebrates to monitor or manage these ecosystems

Jsou morfologicky degradované úseky toků zdrojem tepelného zněčištění vody?

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Actinotignum schaalii: Relation to Concomitants and Connection to Patients’ Conditions in Polymicrobial Biofilms of Urinary Tract Catheters and Urines

Actinotignum schaalii is an emerging, opportunistic pathogen and its connection to non-infectious diseases and conditions, such as prostate or bladder cancer, or chronic inflammation has been proposed. Here, we analyzed 297 urine, ureteral and urinary catheter samples from 128 patients by Polymerase Chain Reaction followed by Denaturing Gradient Gel Electrophoresis and Sequencing (PCR-DGGE-S), and culture, and 29 of these samples also by 16S rRNA Illumina sequencing, to establish A. schaalii’s prevalence in urinary tract-related samples, its relation to other bacteria, and its potential association with patients’ conditions and samples’ characteristics. A. schaalii-positive samples were significantly more diverse than A. schaalii negative and between-group diversity was higher than intra-group. Propionimicrobium lymphophilum, Fusobacterium nucleatum, Veillonella sp., Morganella sp., and Aerococcus sp. were significantly more often present in A. schaalii-positive samples; thus, we suggest these species are A. schaalii’s concomitants, while Enterobacter and Staphylococcaceae were more often identified in A. schaalii-negative samples; therefore, we propose A. schaalii and these species are mutually exclusive. Additionally, a significantly higher A. schaalii prevalence in patients with ureter stricture associated hydronephrosis (p = 0.020) was noted. We suggest that A. schaalii could be an early polybacterial biofilm colonizer, together with concomitant species, known for pro-inflammatory features