The use of Continuously Operating Reference Stations, both singly and as part of an active network, is widely employed in surveying, engineering and other geomatics applications, achieving high accuracy positioning even in real time. With an active network the measurements of the reference stations are processed jointly in order to model the errors and compute network RTK corrections. Due to distance dependent errors (ionospheric and tropospheric delays), single base RTK positioning accuracy decreases with increased baseline length. However, the network solution (NRTK) retains the accuracy and the time to fix ambiguities (TTFA) at a constant level. This study aims to contribute to the scientific research on real time positioning based on active networks. In Southern Spain, ERGNSS, a national CORS network that provides GNSS data for post-processing and real time single- b ased reference station corrections, shares territory with the Andalusian Positioning Network (RAP), a local active network. RAP provides network an d single-based RTK corrections. In order to analyze the quality of real time positioning based on both networks, several tests have been performed on a sample of test points. The reference frame, the time to fix ambiguity resolution, precision, accuracy and repeatability of RTK positioning are considered as the evaluation parameters. The results confirm that the RAP network complements the precise positioning services provided by the ERGNSS network, ensuring accurate real time positioning, full cove rage and reliable positioning services in the Andalusian Community., Mª Selmira Garrido, Antonio J. Gil and Rafael Gaitán., and Obsahuje bibliografické odkazy
In this study we evaluate how variations in taxonomic composition and physical structure of macrophyte stands affect plant-dwelling chironomid assemblages in highly variable macrophyte assemblages in two densely vegetated backwaters. By using multivariate explanatory techniques we found that similar vegetation composition did not unequivocally relate to similar chironomid assemblages, moreover the diversity of macrophyte stands did not correlate with the taxonomic diversity of chironomid assemblages in the backwaters investigated. Taxonomic composition and structural characteristics of the vegetation had little influence on the taxonomic or functional (i.e. feeding groups) composition of chironomid assemblages inhabiting them. Similarly, there are only weak relationships between the distribution of certain chironomid species or functional feeding groups and the environmental variables investigated. In general, the structure of the vegetation was more closely associated with the distribution of dominant chironomid taxa than compositional variables (i.e. density of specific macrophyte taxa). In summary, the structure of aquatic vegetation (i.e. position, size of a stand of vegetation, total plant density) and characteristics of the environment where it develops may be more important in shaping plant-dwelling chironomid assemblages than the taxonomic composition of the vegetation., Mónika Tóth ... [et al.]., and Obsahuje seznam literatury
Monitoring of bushmeat markets has traditionally been seen as a source of faunistic and ecological data on mammal communities in West Africa. Nonetheless, it is largely unexplored whether datasets coming from monitoring of large “hub” markets in towns can reliably picture the mammal faunas and community compositions at the local level. Here, Swali market in Bayelsa State, Nigeria, that is one of the largest bushmeat markets in the Niger Delta, was monitored for six months in 2013-2014. Data from Swali
market were compared with those collected during regular field surveys at five protected forests situated within 15 km radius from the market. A total of 21 mammal species was recorded at Swali versus 29 in the five protected forests. The trade was more intense by wet season. There was a statistically significant linear relationship between mean weight of the sold mammal and its price. A considerable portion of species that occur at the protected forests did not occur in the market samples, including the very rare species and the small-sized species. However, the abundance in the market of the common species was positively related to their apparent field abundance in the forest reserves. Therefore, it is concluded that large-sized bushmeat markets did not depict reliably the whole faunal composition
and the community structure of mammals in West Africa, although these types of surveys are sufficient to characterize the abundance distribution of the common species at the regional scale.
In order to study a possible effect of mini-invasive heart intervention on a response of hypothalamo-pituitary-adrenal stress axis, we analyzed four stress markers (cortisol, cortisone, DHEA and DHEAS) in 25 sows using minimally invasive heart catheterisation as the stress factor. The marker levels were assessed in four periods of the experiment, (1) the baseline level on the day before intervention, (2) after the introduction of anesthesia, (3) after conducting tissue stimulation or ablation, and (4) after the end of the catheterisation. For statistical analyses we used the non-parametric Friedman test for four dependent samples (including all four stages of the operation) or three dependent samples (influence of operation only, baseline level was excluded). Statistically significant differences in both Friedman tests were found for cortisol and for cortisone. Significant differences for DHEA as well as for DHEAS were found for all tested stages but not for the effect of operation itself. We have concluded that cortisol levels are blunted by the influence of anesthesia after its administration, and therefore decrease back to the baseline at the end of the operation. The other markers (cortisone, DHEA and DHEAS) acted as balanced systems against the injurious stress effect., H. Skarlandtová, M. Bičíková, P. Neužil, M. Mlček, V. Hrachovina, T. Svoboda, E. Medová, J. Kudlička, A. Dohnalová, Š. Havránek, H. Kazihnítková, L. Máčová, E. Vařejková, O. Kittnar., and Obsahuje bibliografii
Action potentials (APs) and the force of isometric contractions of the right ventricular papillary muscles were measured in adult and newborn guinea-pigs. The measurements were carried out in the steady state with the rate of stimulation of 0.1, 1, and 2 Hz, and further some measurements were done in which Sr2+ was substituted for Ca2- The duration of APs of the newborn animals without pharmacological treatment was significantly shorter in comparison with that of the adults at all the used stimulation frequencies. An analogous sensitivity was found in the contractile force to increased stimulation frequency and when the steady state stimulation was discontinued by the insertion of interpolated extrasystoles in papillary muscles of adult or newborn animals. The biphasic contractions of papillary muscles were evoked in both groups of animals by the incomplete substitution of Sr2+ by Ca2+ in the presence of isoprenaline. The early component of the biphasic contractions had a faster course as compared to the late component and disappeared in the presence of caffeine in both groups of animals. Our results suggest that the heart cells of newborn guinea-pigs probably possess the sarcoplasmic reticulum (SR), whose function does not differ in quality from that of the adult guinea-pigs. The postnatal prolongation of APs is therefore not probably the result of postnatal development changes of the functions of SR, but could be related to changes in the relations between the surface and volume of the heart cell during its growth.
Two hundred and ninety-nine specimens of Atherina boyeri, collected from five Mediterranean sites (three from the open sea (Chioggia, Catania and Gaeta) and two from river mouths (the Birgi and S. Bartolomeo rivers) were analyzed in order to confirm previous genetic studies. Eigtheen loci were scored from 12 enzymatic systems, 3 of which were polymorphic: EST*, PGM* and PGI*. Mean Fst value (0.300, pFst and genetic distance revealed that samples from the river mouths (Birgi and S. Bartolomeo) were grouped separately from the open sea samples (Catania, Chioggia and Gaeta). These results are in agreement with the most recent classification, which considers A. boyeri as a complex of 3 different species.