The effects of interspecific interactions between bloom forming cyanobacteria and Scenedesmus quadricauda (chlorophyta) on their photophysiology

Eutrophication and enhanced external nutrient loading of lakes and seas are most clearly reflected by increased cyanobacterial blooms, which are often toxic. Freshwater cyanobacteria produce a number of bioactive secondary metabolites, some of which have allelopathic properties, significantly influencing the biological processes of other algae, thereby affecting species composition and succession of the phytoplankton. The goal of this work was to investigate the influence of bloom-forming cyanobacterial exudates on the photophysiology of the green alga Scenedesmus quadricauda by chlorophyll fluorescence analysis. We were able to prove the effect of algal cell-free filtrates on the performance of S. quadricauda and demonstrate for the first time that the freshwater picocyanobacterium Cyanobium gracile has strong negative impact on the coexisting green alga. Neither the cyanotoxin (MYC, CYN and ATX) producing, nor the non-toxic strains showed any systematic effect on the production of S. quadricauda. Various strains of the cyanobacterium Cylindrospermopsis raciborskii inhibited the performance of the green alga independently of their origin. Our results urge further studies for a better understanding of the factors affecting the release of allelopathic compounds and the mechanisms of their effects on target organisms

Co-ordination and public administration in a global economy — A Hungarian point of view

The purpose of social co-ordination mechanisms is to co-ordinate the activities of individuals and organisations specialised in the distribution of work. The paper reviews five basic types of mechanisms: market, bureaucratic, ethical, aggressive and co-operative co-ordination. Today’s world operates on the basis of a duality: international cooperation is based on nation states, in which the public administrations work according to bureaucratic coordination. However, the increasingly globalised market responds to the logic of market coordination. The article argues that in terms of understanding the working of public administration, the various coordination mechanisms are of crucial importance, especially where various mechanisms meet, such as the relationship between nation states and multinational corporations

A 275–425-GHz Tunerless Waveguide Receiver Based on AlN-Barrier SIS Technology

We report on a 275–425-GHz tunerless waveguide receiver with a 3.5–8-GHz IF. As the mixing element, we employ a high-current-density Nb–AlN–Nb superconducting–insulating– superconducting (SIS) tunnel junction. Thanks to the combined use of AlN-barrier SIS technology and a broad bandwidth waveguide to thin-film microstrip transition, we are able to achieve an unprecedented 43% instantaneous bandwidth, limited by the receiver's corrugated feedhorn. The measured double-sideband (DSB) receiver noise temperature, uncorrected for optics loss, ranges from 55 K at 275 GHz, 48 K at 345 GHz, to 72 K at 425 GHz. In this frequency range, the mixer has a DSB conversion loss of 2.3 1 dB. The intrinsic mixer noise is found to vary between 17–19 K, of which 9 K is attributed to shot noise associated with leakage current below the gap. To improve reliability, the IF circuit and bias injection are entirely planar by design. The instrument was successfully installed at the Caltech Submillimeter Observatory (CSO), Mauna Kea, HI, in October 2006

Extraction methods for phycocyanin determination in freshwater filamentous cyanobacteria and their application in a shallow lake

Phycocyanin (PC) is one of the water-soluble accessory pigments of cyanobacteria species, and its concentration in aquatic systems is used to estimate the presence and relative abundance of blue-green algae. PC concentration and the PC/Chl-a ratio of four N2-fixing filamentous cyanobacteria strains (Cylindrospermopsis raciborskii, Anabaena spiroides, Aphanizomenon flos-aquae and Aphanizomenon issatschenkoi) common to Lake Balaton (Hungary) were determined using repeated freezing and thawing. A strong linear correlation was found between the extracted PC and Chl-a concentrations for all strains at high Chl-a concentrations (almost stable PC/Chl-a ratio in the range of 20−100 µg l−1 Chl-a). Extraction of PC and Chl-a from samples with low biomass of cyanobacteria (less than 20 µg l−1 Chl-a) proved to be unreliable using the standard protocol of freeze–thaw cycles (coefficients of variation exceeding 10–15%). In order to find an extraction method that is robust in fresh waters characterized by low algae biomass (e.g. Lake Balaton), the effectiveness of four extraction methods (repeated freeze–thaw method and homogenization with mortar and pestle, Ultrasonic, and Polytron homogenizer) were compared using C. raciborskii. It was found that the efficiency of extraction of phycocyanin was highest when a single freeze–thaw cycle was followed by sonication (25% additional yield compared with using the freeze–thaw method alone). Applying this combined method to surface water samples of Lake Balaton, a strong correlation was found between PC concentration and cyanobacterial biomass (R 2 = 0.9436), whilst the repeated freezing–thawing method found no detectable PC content. Here we show that the combined sonication/freeze–thaw method could be suitable for measuring filamentous cyanobacteria PC content, even at low concentrations; as well as for the estimation of cyanobacterial contribution to total biomass in fresh waters

Missing observations in ARIMA models: skipping strategy versus additive outlier approach

Optimal estimation of missing values in ARMA models is typically performed by using the Kalman Filter for likelihood evaluation, "skipping" in the computations the missing observations, obtaining the maximum likelihood (ML) estimators of the model parameters, and using some smoothing algorithm. The same type of procedure has been extended to nonstationary ARIMA models in G6mez Maravall (1994). An alternative procedure suggests filling in the holes in the series with arbitrary values and then performing ML estimation of the ARIMA model with Additive Outliers (AO). When the model parameters are not known the two methods differ, since the AO likelihood is affected by the arbitrary values. We develop the proper likelihood for the AO approach in the general non-stationary case and show the equivalence of this and the skipping method. Computationally efficient ways to apply both procedures, based on an Augmented Kalman Filter, are detailed. Finally, the two methods are compared through simulation, and their relative advantages assessed; the comparison also includes the AO method with the uncorrected likelihood

Optimal Cyanobacterial Pigment Retrieval from Ocean Colour Sensors in a Highly Turbid, Optically Complex Lake

To date, several algorithms for the retrieval of cyanobacterial phycocyanin (PC) from ocean colour sensors have been presented for inland waters, all of which claim to be robust models. To address this, we conducted a comprehensive comparison to identify the optimal algorithm for retrieval of PC concentrations in the highly optically complex waters of Lake Balaton (Hungary). MEdium Resolution Imaging Spectrometer (MERIS) top-of-atmosphere radiances were first atmospherically corrected using the Self-Contained Atmospheric Parameters Estimation for MERIS data v.B2 (SCAPE-M_B2). Overall, the Simis05 semi-analytical algorithm outperformed more complex inversion algorithms, providing accurate estimates of PC up to ±7 days from the time of satellite overpass during summer cyanobacteria blooms (RMSElog 0.66, p < 0.001). In-depth analysis of the Simis05 algorithm using in situ measurements of inherent optical properties (IOPs) revealed that the Simis05 model overestimated the phytoplankton absorption coefficient [aph(λ)] by a factor of ~2. However, these errors were compensated for by underestimation of the mass-specific chlorophyll absorption coefficient [a*chla(λ)]. This study reinforces the need for further validation of algorithms over a range of optical water types in the context of the recently launched Ocean Land Colour Instrument (OLCI) onboard Sentinel-3

Impact of CT-apelin and NT-proBNP on identifying non-responders to cardiac resynchronization therapy

CONTEXT: Assessment of response to cardiac resynchronization therapy (CRT) is essential. OBJECTIVE: To assess the predictive value of CT-apelin together with NT-proBNP in patients undergoing CRT. METHODS: Serum CT-apelin and NT-proBNP were measured by ELISA before, and 6-month after CRT. Primary endpoint was non-response (<4% increase in LVEF) after 6-month. RESULTS: From 81 patients, 15 proved to be non-responders. Six-month CT-apelin was superior compared to NT-proBNP in identifying non-responders by multivariate ROC (CT-apelin:p = 0.01, NT-proBNP:p = 0.13) and by logistic regression (CT-apelin:p = 0.01, NT-proBNP:p = 0.41) analyzes. CONCLUSION: Six-month CT-apelin might be valuable novel biomarker in identifying non-responders to CRT that was superior to NT-proBNP