Soil-invertebrate feeding birds can be exposed to high doses of toxic metals trough their diet. Recently, we have shown that nestling rooks Corvus frugilegus from several rookeries in Poland have a cadmium (Cd) tissue level diagnostic for acute contamination as well as an elevated level of lead (Pb). To explain the potential pathway of bioaccumulation of 11 essential and non-essential elements, including two metals of primary concern (Cd and Pb), in target issues of these nestlings, we analyzed the relationships between the dietary characteristics of stomach content (mass of digesta, number of cereal grains, plant and animal items, and grit particles) and concentrations of metals in the liver, kidneys, lung, muscles and bones. Our analysis showed in total 17 (8 negative and 9 positive) statistically signigicant relationships between the five analyzed dietary characteristics of stomach content nad concentrations of metals in the liver, kidneys, muscles and bones. We found a significant positive relationship between the number of animal food items and Cd-level in kidneys; and a negative relationship bewteen the number of plant items and Pb-level in the liver, and between the number of grit particles and Pb-level in kidneys. Despite the limitations of our study due to the different degree of digestion of some food items, our findings suggest high bioavailability of Cd from animal food items and a low level or reduce gastrointestinal absorption of Pb from plant food (mainly cereals). We urge further research on absorption of Cd and Pb from different dietary components and application of diet analysis to explain the complex nature of bioaccumulation of anthropogenic contaminants in the internal organs and tissues of birds and other species of animals, especially in species with a mixed plant-animal diet.
Host-parasite relationships between the Daubenton's bat, Myotis daubentonii Kuhl, 1817 (Chiroptera: Vespertilionidae), and its haematophagous ectoparasite, the mite Spinturnix andegavinus Kolenati, 1857 (Acari: Spinturnicidae), were subjected to analyses based on data gathered during a six-year study (1999-2004) within a single study area in South Bohemia, Czech Republic. Seven hundred and fifty-one Daubenton's bats were examined by screening wing membranes with an intensive light source, resulting in 4,690 recorded mites. Sex, age, weight and reproductive state were evaluated for each bat. A body condition index was calculated as a ratio of weight to forearm length. The seasonal course of mite infestation displayed distinct dynamics with the peak during the lactation and post-lactation periods coinciding with occurrence of the most numerous colonies of Daubenton's bats in the study area. Infestation rates differed between the two sexes, being higher in adult females than adult males. Juvenile bats of both sexes (with no differences between males and females) were the most infested group of all. Pregnant females had a significantly higher parasite load than non-pregnant ones, while no differences in infestation rates were found between lactating and non-lactating females. The analyses of the relationship between parasite load and body condition of bats revealed no common trends for all sex- and age-related groups. Two possible explanations are suggested and discussed: (1) There is no true relationship between the two tested variables and, thus, the significant results were attained due to a random statistical effect. (2) Different underlying causal mechanisms may exist that influence parasite load and, especially, body condition, with respect to the particular sex and age category of bats. The seasonal roosting dynamics of the Daubenton's bat are suggested to be the result not only of changing energetic demands of resident population members, but also of coevolutionary strategies within host-parasite relationships.
An attempt was made to determine the relationship between the characteristics of electrical activity of the hypertrophied myocardium of rats at the cellular level and at the level of the whole heart after a one-month left ventricular pressure overload. Such an animal model has already been demonstrated to be highly resistant to epinephrine-induced arrhythmias. Since severe ventricular arrhythmias often occur in patients with cardiac hypertrophy, ventricular vulnerability might depend on some electrophysiological characteristics of the heart related to the stage of hypertrophy. Using the "floating" microelectrode technique, the computed characteristics of cardiac transmembrane action potentials (AP) of the left and right epicardium cells were compared in situ to computed characteristics of the electrocardiograms in anaesthetized control rats (group C) and in rats with left ventricular hypertrophy (group H) induced by a one-month suprarenal constriction of the abdominal aorta. The aortic pressure overload caused a significant (p< 0.001) and marked increase in AP duration of left ventricular cells: APD 30 and APD 80 were 29 ±3 ms and 89 ±6 ms, respectively, in group H and 14 ±1 ms and 53 ±2 ms in group C. The same modifications were observed in right ventricular cells when right hypertrophy was present. Simultaneous electrocardiograms exhibited a significant (p<0.01) prolongation of P-R, Q-S and T duration and T wave flattening in group H (63 ±2 ms, 32 ±3 ms, 109 ±5 ms and 0.25 ±0.03 mV as compared with 53 ±1 ms, 20 ±1 ms, 88 ±2 ms and 0.40 ±0.04 mV in group C). After a one-month aortic overload in rats, both left and right ventricles are hypertrophied and have the same electrophysiological characteristics: in this model, at this stage of hypertrophy, some factors favouring ventricular arrhythmias are missing. The corresponding flattening of the T wave in the ECG might be of clinical relevance.
Winter weather limits populations of resident bird species. Although many small-scale or speciesspecific studies illustrated this fact, our knowledge of interspecific differences in population responses to winter temperatures is incomplete due to lack of community-level studies. For this purpose, we have used long-term monitoring data on breeding bird populations of 37 common bird species wintering in the Czech Republic. We predicted that species will differ in their relationship between winter temperature and abundance with respect to their body mass and dietary niche. Smaller species having relatively higher energy expenditure should show closer relationship between breeding abundance and winter temperature than larger species. Concerning dietary niche, abundance of species feeding on animals should be more affected by temperature than abundance of species feeding on plants or omnivorous species. Our results confirmed the second prediction: populations of species preying on animals followed winter temperatures more closely than populations of species feeding on both animals and plants. Food-mediated mortality is probably more important than direct effects of low temperatures. In general, relationships between abundance and temperature were relatively weak in most species and we suggest that possible changes in winter temperatures may not seriously affect populations of common breeding birds in the Czech Republic.
Performance evaluation of classifiers is a crucial step for selecting the best classifier or the best set of parameters for a classifier. Receiver Operating Characteristic (ROC) curves and Area Under the ROC Curve (AUC) are widely used to analyse performance of a classifier. However, the approach does not take into account that misclassification for different classes might have more or less serious consequences. On the other hand, it is often difficult to specify exactly the consequences or costs of misclassifications. This paper is devoted to Relative Cost Curves (RCC) - a graphical technique for visualising the performance of binary classifiers over the full range of possible relative misclassification costs. This curve provides helpful information to choose the best set of classifiers or to estimate misclassification costs if those are not known precisely. In this paper, the concept of Area Above the RCC (AAC) is introduced, a scalar measure of classifier performance under unequal misclassification costs problem. We also extend RCC to multicategory problems when misclassification costs depend only on the true class.
Let R be a commutative Noetherian ring and let C be a semidualizing R-module. We prove a result about the covering properties of the class of relative Gorenstein injective modules with respect to C which is a generalization of Theorem 1 by Enochs and Iacob (2015). Specifically, we prove that if for every Gc-injective module G, the character module G+ is Gc-flat, then the class GIc(R) Ac(R) is closed under direct sums and direct limits. Also, it is proved that under the above hypotheses the class GIc(R) Ac(R) is covering., Elham Tavasoli, Maryam Salimi., and Obsahuje bibliografii
The factors influencing plant species diversity in secondary and ancient forests can differ. Apart from environmental variability caused by natural conditions, secondary forests are influenced by historical factors (previous human activity). However, the effect of historical factors on vegetation is not fully understood. Secondary forests that have developed in abandoned villages in the Doupovské hory mountains, Czech Republic, were surveyed and compared with ancient forests in an attempt to determine the effect of historical factors and separate it from that of natural gradients. The results show that secondary forests in abandoned villages form a unique type of vegetation that differs from ancient forests mainly in the presence of species indicating a high nutrient content and high pH of the soils. This indicates that the previous high nutrient input in the villages still influences the soils and causes the differences. Variability of village forests is influenced mainly by a gradient in the available phosphorus content of the soils, soil moisture (approximated by wetness index) and organic matter content. The pattern in the phosphorus content and pH indicate a different intensity of historical influence in the centre compared to the periphery of the villages. Vegetation variability is modified by former land-use and village structure. The effect of historical factors is relatively strong and cannot be explained by coincidental initial conditions.
In the paper, the notion of relative polarity in ordered sets is introduced and the lattices of $R$-polars are studied. Connections between $R$-polars and prime ideals, especially in distributive sets, are found.
We extend the notion of a relatively pseudocomplemented meet-semilattice to arbitrary posets. We show some properties of the binary operation of relative pseudocomplementation and provide some corresponding characterizations. We show that relatively pseudocomplemented posets satisfying a certain simple identity in two variables are join-semilattices. Finally, we show that every relatively pseudocomplemented poset is distributive and that the converse holds for posets satisfying the ascending chain condition and one more natural condition. Suitable examples are provided.
This paper proposes new stability conditions for interval type-2 fuzzy-model-based (FMB) control systems. The type-1 T-S fuzzy model has been widely studied because it can represent a wide class of nonlinear systems. Many favorable results for type-1 T-S fuzzy model have been reported. However, most of conclusions for type-1 T-S fuzzy model can not be applied to nonlinear systems subject to parameter uncertainties. In fact, Most of the practical applications are subject to parameters uncertainties. To address above problem, an interval type-2 T-S fuzzy model has been proposed to approximate nonlinear systems subject to parameter uncertainties, and stability conditions for interval type-2 FMB control systems have also been presented in the form of linear matrix inequalities (LMIs). The aim of this paper is to relax the existing stability conditions. The new stability conditions in terms of LMIs are derived to guarantee the stability of interval type-2 FMB control systems. The theoretical poof is given to show the proposed conditions reduce the conservativeness in stability analysis. Several numerical examples are also provided to illustrate the effectiveness of the proposed conditions.