Use of Models to Support the Monitoring Requirements in the Water Framework Directive

Implementation of the EU Water Framework Directive (WFD) poses many new challenges to European water managers. Monitoring programmes play a key role to assess the status and identify possible trends in the environmental conditions of river basins; to gain new knowledge on water processes and to assess to which extent implemented measures actually have the expected effects in terms of improving the environmental status. Despite a general acknowledgement in the scientific community on the benefits of using monitoring and modelling jointly, it has not been the common practise in the European monitoring programmes so far. Several obstacles may be identified which limits the joint use of monitoring and modelling, such as lack of the required skill, lack of time, lack of confidence in models but also a lack of awareness on how models can be used in practise. In this paper we provide examples on how modelling can support the monitoring programmes to meet the objectives of the monitoring programmes in the WFD more efficiently. The extent to which the monitoring requirements in the WFD can be expected to supply sufficient data for modelling purposes is further addressed. This question is, however, not well posed, as the data requirement for modelling is highly dependent on the required accuracy of the model results.     

Heat treatment of molybdenum under vacuum conditions

Oxide coverage of molybdenum plays an important role in several applications, for example in lighting industry. Surface conditioning procedures were simulated in an XPS instrument by in situ heat treatments while monitoring the surface composition and changes in the chemical states of molybdenum. Heat treatments have been made at different temperatures between 435 and 690 °C under vacuum conditions. It has been observed that during heating the molybdenum test samples the native MoO₃ layer on the surface dissociates, and a layer of suboxides forms on the surface. This layer hinders the further reduction of the surface, thus reaction speed decreases after the initial phase. It has been established that in the second phase of the heat treatment the activation energy of the process is 1.1 ± 0.2 eV. Reduction of MoO₃ to elemental molybdenum runs through two intermediate states: Mo⁶⁺ → Mo⁵⁺ → Mo⁴⁺ → Mo⁰.     

Climatic conditions for operation of wind turbines in Hungary

According to wind-climatic requirement of wind farms wind speed should exceed the so called cut-in speed. If this inequality is realized then regarding the wind-climatic features of Hungary the following conditions may occur: the wind turbine is operating with high probability, energy is generated; it is working in a regulated mode with low probability; it is not working with very low probability. Therefore in terms of continuous energy production by wind one question arises: are there any temporal and/or orographic shifts in different heights compared to the wind-climatic condition mentioned above. In this paper this question is analyzed on the basis of seven Hungarian meteorological stations that have hourly measured wind speed data considering the period between 1991 and 2000. The probability of wind speeds exceeding 3 m/s, statistics of wind speed intervals higher and lower than 3 m/s and statistics of average hourly wind speed intervals higher than 3 m/s were analyzed at the heights of 10, 30 and 60 m. A statistical parameter that is proportional to the average specific wind power of a day in a time period was defined and, its connection to the average length of those intervals that have higher or equal hourly average wind speeds more than 3 m/s in a given month was investigated. With the help of such parameters the value of monthly average specific wind power can be estimated.     

A polymer-based spiky microelectrode array for electrocorticography

The advanced technology of microelectromechanical systems (MEMS) makes possible precise and reproducible construction of various microelectrode arrays (MEAs) with patterns of high spatial density. Polymer-based MEMS devices are gaining increasing attention in the field of electrophysiology, since they can be used to form flexible, yet reliable electrical interfaces with the central and the peripheral nervous system. In this paper we present a novel MEA, designed for obtaining neural signals, with a polyimide (PI)—platinum (Pt)—SU-8 layer structure. Electrodes with special, arrow-like shapes were formed in a single row, enabling slight penetration into the tissue. The applied process flow allowed reproducible batch fabrication of the devices with high yield. In vitro characterization of the electrode arrays was performed with electrochemical impedance spectroscopy in lactated Ringer’s solution. Functional tests were carried out by performing acute recordings on rat neocortex. The devices have proven to be convenient tools for acute in vivo electrocorticography.     

Exciton recombination dynamics in CdSe nanowires: bimolecular to three-carrier Auger kinetics

Ultrafast relaxation dynamics of charge carriers in CdSe quantum wires with diameters between 6 and 8 nm are studied as a function of carrier density. At high electron-hole pair densities above 10(19) cm(-3) the dominant process for carrier cooling is the "bimolecular" Auger recombination of one-dimensional (1D) excitons. However, below this excitation level an unexpected transition from a bimolecular (exciton-exciton) to a three-carrier Auger relaxation mechanism occurs. Thus, depending on excitation intensity, electron-hole pair relaxation dynamics in the nanowires exhibit either 1D or 0D (quantum dot) character. This dual nature of the recovery kinetics defines an optimal intensity for achieving optical gain in solution-grown nanowires given the different carrier-density-dependent scaling of relaxation rates in either regime.     

Composition of muscle tissue lipids of silver carp and bighead carp

Lipids have a complex role in the nutritional value of food. Some polyunsaturated fatty acids, characterized as essential, are extremely important for human health. This is primarily related to α-linolenic acid (18:3n-3), eicosapentaenoic acid (20:5n-3) and docosahexaenoic acid (22:6n-3). Content of polyunsaturated n-3 fatty acids is usually much higher in lipids of marine fish than in freshwater fish. Previous investigations have shown that muscle tissue of silver carp and bighead carp from fish farms may be a rich source of essential fatty acids. Because of that, the objective of this work was to examine contents and composition of fatty acids and total lipids in the muscle tissue of silver and bighead carp, with the aim to find out whether there are significant differences in this respect between the two species and to what extent the harvest season can influence the composition of lipids in these freshwater fish. This study showed that there is no significant difference either in the content of polyunsaturated n-3 and n-6 fatty acids, or in the n-6/n-3 fatty acid ratio in these two fish species. The lipids of both the silver and bighead carp from the spring harvest have significantly higher contents of the n-3 acids and a significantly lower n-6/n-3 ratio than fish from the autumn harvest.     

Ala226 to Gly and Ser189 to Asp mutations convert rat chymotrypsin B to a trypsin-like protease

In a previous successful attempt to convert trypsin to a chymotrypsin-like protease, 15 residues of trypsin were replaced with the corresponding ones in chymotrypsin. This suggests a complex mechanism of substrate recognition instead of a relatively simple one that only involves three sites, residues 189, 216 and 226. However, both trypsin-->elastase and chymotrypsin-->trypsin conversion experiments carried out according to the complex model resulted in non-specific proteases with low catalytic activity. Chymotrypsin used in the latter studies was of B-type, containing an Ala residue at position 226. Trypsins, however, contain a conserved Gly at this site. The substantially decreased trypsin-like activity of the G226A trypsin mutant also suggests a specific role for this site in substrate binding. Here we investigate the role of site 226 by introducing the A226G substitution into chymotrypsin-->trypsin mutants which were constructed according to both the simple (S189D mutant) and the complex model (S(1) mutant) of specificity determination. The kinetic parameters show that the A226G substitution in the S(1) mutant increased the chymotrypsin-like activity, while the trypsin-like activity did not change. In contrast, this substitution in the S189D chymotrypsin mutant resulted in a 100-fold increase in trypsin-like activity and a trypsin-like specificity profile as tested on a competing oligopeptide substrate library. Additionally, the S189D+A226G mutant is the first trypsin-like chymotrypsin that undergoes autoactivation, an exclusive property of trypsinogen among pancreatic serine proteases.     

Learning Tetris using the noisy cross-entropy method

The cross-entropy method is an efficient and general optimization algorithm. However, its applicability in reinforcement learning (RL) seems to be limited because it often converges to suboptimal policies. We apply noise for preventing early convergence of the cross-entropy method, using Tetris, a computer game, for demonstration. The resulting policy outperforms previous RL algorithms by almost two orders of magnitude.     

Enhancing wireless video streaming using lightweight approximate authentication

In this paper, we propose a novel lightweight approximate authentication algorithm that provides efficient protection for wireless video streaming where attacks on the stream are possible, but classical integrity protection algorithms are impractical because bit errors occur naturally. The benefits of the proposed algorithm over other algorithms are fast execution and small message authentication code size. Moreover, the approximate authentication supports error resilient video decoding by dropping seriously damaged packets, thus improving the perceived quality of the video stream. The performance of the algorithm is demonstrated via numerical analysis, simulations and measurements over modeled and real wireless channels.