Primary productivity in marine waters is widely estimated by the measurements of 14C incorporation, the underwater light climate, and the absorption spectra of phytoplankton. In bio-optical models the quantum efficiency of carbon fixation derived from 14C incorporation rates, the photosynthetically absorbed radiation derived from the underwater light climate, and the phytoplankton absorption spectra are used to calculate time- and depth-integrated primary productivity. Due to the increased sensitivity of commercially available fluorometers, chlorophyll a in vivo fluorescence became a new tool to assess the photosynthetic activity of phytoplankton. Since fluorescence data yield only relative photosynthetic electron transport rates, a direct conversion into absolute carbon fixation rates is not possible. Here, we report a procedure how this problem can be adressed in freshwater phytoplankton. We adapted a marine bio-optical model to the freshwater situation and tested if this model yields realistic results when applied to a hypertrophic freshwater reservoir. Comparison of primary productivity derived from 14C incorporation to primary productivity derived from Chl a fluorescence showed that the conversion of fluorescence data into carbon fixation rates is still an unsolved problem. Absolute electron transport rates calculated from fluorescence data tend to overestimate primary production. We propose that the observed differences are caused mainly by neglecting the package effect of pigments in phytoplankton cells and by non-carbon related electron flow (e.g., nitrogen fixation). On the other hand, the 14C incorporation rates can be artificially influenced by "bottle effects", especially near the water surface, where photoinhibition, photorespiration, and Mehler reaction can play a major role. and M. Gilbert ... [et al.].
Real time prediction of return periods of flood events that might occur in the course of anticipated dangerous meteorological situations at a catchment could be useful as additional information for decision makers involved in flood warning. Such a method is proposed in the paper for the Torysa basin in the western part of East Slovakia for rainfall-induced floods. A conceptual rainfall-runoff model with a daily time step was adopted for modelling of the runoff. The study of the relationship between the modelled basin’s soil moisture index at the beginning of the annual maximum floods and the flood-causing precipitation totals showed no dependence between these two quantities. Based on that finding, several scenarios involving the independent joint occurrence of synthetic extreme precipitation and antecedent basin saturation indexes were constructed. Using event-based flood simulations, synthetic flood waves were generated for these scenarios with the rainfall-runoff model. The relationships between the return periods of the synthetic precipitation and the return periods of the simulated floods were analysed, and the effect of antecedent basin saturation index on the extremity of the floods was quantified. Critical values of the basin saturation index leading to floods with higher return periods than the return period of flood-causing precipitation were suggested. A simple method of implementing such critical values into real time flood risk warnings in a hydrological forecasting and warning system in the Torysa basin was outlined. and Predpovedanie N-ročnosti povodní v reálnom čase pri výskyte kritických meteorologických situácií na povodiach je dôležité ako dodatočná informácia z hľadiska rozhodovacieho procesu v protipovodňovom varovnom systéme a následných opatreniach na povodiach. Táto štúdia bola preto zameraná na posudzovanie vzájomného pôsobenia extrémnych príčinných tekutých zrážok a rôznych stavov predchádzajúceho nasýtenia na pilotnom povodí Torysy po Prešov. Pre modelovanie odtoku na povodí bol použitý koncepčný zrážkovo-odtokový model s denným krokom. Pri výbere počiatočných podmienok vzniku povodní sme posudzovali rôzne stavy nasýtenia povodia pred vznikom najväčších ročných povodní, ktoré sa vyskytli na uvedenom povodí v minulosti. Na základe kombinácií modelových extrémnych príčinných zrážok s rôznymi stavmi predchádzajúceho nasýtenia povodia sme hydrologickým modelovaním simulovali odtok z povodia. Analyzoval sa vzťah medzi dobou opakovania modelových zrážok a simulovaných povodní a následne sa kvantifikoval vplyv predchádzajúceho nasýtenia povodia na extremitu odtoku. Určili sa kritické hodnoty nasýtenia povodia, kedy doba opakovania povodní prevyšuje hodnotu doby opakovania príčinných zrážok. Záverom bola navrhnutá jednoduchá metóda implementácie týchto kritických hodnôt pri predpovedaní povodní v reálnom čase na povodí Torysy.
At present days, the requirements on reliability analysis of power oil transformers are increasing in technical practice. Properly estimated reliability characteristics inform the user how to service machine, and such estimation also saves the user‘s financial means. In the first part of this paper, the models for estimating reliability characteristics only from a set of times to failure of power oil transformers are described. Additionally, the Cox model, which enables for such machines to complete reliability analysis with diagnostic measurements, is introduced. In the last part of this paper, the Cox model is enhanced by factor analysis and moreover, the acquired results are compared with real behaviour of tested power oil transformers during operation. and Obsahuje seznam literatury
This paper contains the studies of the noise level in GPS (Global Positioning System) time series. As the data for this research the authors used changes of the geodetic coordinates of the ASG-EUPOS and associated (Slovak and Czech) sites. The method of precise GPS observations processing in short-time intervals was worked out in the Centre of Applied Geomatics, Military University of Technology. The authors focus on the diurnal and sub-diurnal frequency bands (tidal) as the tidal effects influence the sites’ positions at the most and the model used in the standard processing software does not contain geodetic coefficients. Thus the residual values of the geodetic coordinates time series should hold some information in the shape of coloured noise. The paper comprise short description of the Earth tides phenomenon, the concept of the tidal parameters determination, character of the white and coloured noise and the assessment of the noise estimation from GPS data. As the processed network contains 130 sites the spatial distribution of the noise’s parameters is also investigated., Janusz Bogusz and Bernard Kontny., and Obsahuje bibliografii
Summary characteristics play an important role in the analysis of spatial point processes. We discuss various approaches to estimating summary characteristics from replicated observations of a stationary point process. The estimators are compared with respect to their integrated squared error. Simulations for three basic types of point processes help to indicate the best way of pooling the subwindow estimators. The most appropriate way depends on the particular summary characteristic, edge-correction method and also on the type of point process. The methods are demonstrated on a replicated dataset from forestry.
An estimation procedure for suspended sediment concentrations based on the intensity of backscattered sound of acoustic Doppler current profilers (ADCP) is introduced in this paper. Based on detailed moving and fixed boat ADCP measurements with concurrent sediment sampling, we have successfully calibrated the estimation method for a reach of River Danube in Hungary, characterized by significant suspended sediment transport. The effect of measurement uncertainty and various data filtering on sediment load determination is also analyzed and quantified. Some of the physical model parameters describing the propagation of sound in water are estimated based on known empirical formulas, while other parameters are derived from measured. Regression analysis is used to obtain a relationship between the intensity of backscattered sound and sediment concentrations. The empirical relationship has been then used to estimate the suspended sediment concentrations from the ADCP data collected in fixed and moving boat measurement operation mode, along verticals and path-lines, respectively. We show that while some measurement uncertainty is inherent to the acoustic Doppler principle, it is further enhanced by the complexity of the near-bottom sediment-laden flow. This uncertainty has then a significant effect on the local sediment load estimation. In turn, reasonable smoothing of raw velocity and backscatter intensity data shows insignificant impact on cross-sectional sediment load estimation.
The stressed state of the rock mass in the area of the Outokumpu deep drill hole, Finland, was investigated by the boundaryelement method in three mutually orthogonal planes with regard for the massif geological structure. It was found that subhorizontal components of the stress field are determined by tectonic forces acting on the boundaries of the European part of the Eurasian lithospheric plate. In the drill hole vertical section the widest variations of this field gradient occur at the depths of an ophiolite sequence in the range of 1.8-2.0 km., Stepan Savchenko and Feliks Gorbatsevich., and Obsahuje bibliografii
Tree transpiration plays a determining role in the water balance of forest stands and in seepage water yields from forested catchments, especially in arid and semiarid regions where climatic conditions are dry with severe water shortage, forestry development is limited by water availability. To clarify the response of water use to climatic conditions, sap flow was monitored by heat pulse velocity method from May to September, 2014, in a 40–year–old Pinus tabulaeformis Carr. plantation forest stands in the semiarid Loess Plateau region of Northwest China. We extrapolated the measurements of water use by individual plants to determine the area–averaged transpiration of the woodlands. The method used for the extrapolation assumes that the transpiration of a tree was proportional to its sapwood area. Stand transpiration was mainly controlled by photosynthetically active radiation and vapor pressure deficit, whereas soil moisture had more influence on monthly change in stand transpiration. The mean sap flow rates for individual P. tabulaeformis trees ranged from 9 to 54 L d−1. During the study period, the mean daily stand transpiration was 1.9 mm day–1 (maximum 2.9 and minimum 0.8 mm day–1) and total stand transpiration from May to September was 294.1 mm, representing 76% of the incoming precipitation over this period. Similar results were found when comparing transpiration estimated with sap flow measurements to the Penman–Monteith method (relative error: 16%), indicating that the scaling procedure can be used to provide reliable estimates of stand transpiration. These results suggested that P. tabulaeformis is highly effective at utilizing scarce water resources in semiarid environments.
We investigate estimators of the asymptotic variance <span class="tex">\ss</span> of a <span class="tex">d</span>-dimensional stationary point process <span class="tex">Ψ</span> which can be observed in convex and compact sampling window <span class="tex"><sub>n</sub>=n W</span>. Asymptotic variance of <span class="tex">Ψ</span> is defined by the asymptotic relation <span class="tex">{Var}(Ψ(<sub>n</sub>)) \sim ß|<sub>n</sub>|</span> (as <span class="tex">n \to ∞</span>) and its existence is guaranteed whenever the corresponding reduced covariance measure <span class="tex">\gamr(\cdot)</span> has finite total variation. The three estimators discussed in the paper are the kernel estimator, the estimator based on the second order intesity of the point process and the subsampling estimator. We study the mean square consistency of the estimators. Since the expressions for the variance of the estimators are not available in closed form and depend on higher order moment measures of the point process, only the bias of the estimators can be compared theoretically. The second part of the paper is therefore devoted to a simulation study which compares the efficiency of the estimators by means of the mean squared error and for several clustered and repulsive point processes observed on middle-sized windows.
The study investigates the effect of administered estrogen on plasma creatine kinase (CK) and lactate dehydrogenase (LD) levels in female ovariectomized rats after downhill running. Rats ovariectomized before sexual maturity were subcutaneously implanted with pellets containing 17β-estradiol or placebo. Three weeks later they were subjected to a 90-min intermittent downhill running protocol. Blood samples were obtained from the jugular vein immediately after and 72 h after exercise for determination of plasma CK, LD and 17β-estradiol levels. A two-way analysis of variance was used for data evaluation. Plasma CK and LD levels were significantly lower (p<0.05) in the estrogen-supplemented, ovariectomized animals which suggests that less muscle damage occurred compared to the controls immediately and 72 h after exercise. Estrogens may have a protective effect on muscle tissue possibly due to their antioxidant and membrane stabilizing properties., S. Sotiriadou, A. Kyparos, V. Mougios, Ch. Trontzos, G. Sidiras, Ch. Matziari., and Obsahuje bibliografii