Engineering geological evaluation of the Of-Solakli hydropower development project (N.E. Turkey)

The Of-Solakli Hydropower Development Project (HDP) is designed to generate 380 MW of electricity through the diversion of six streams into a headrace tunnel and maintaining a head difference of 1 000 m above the underground power station. The tunnel system is located within felsic and mafic magmatic rocks, and volcanogenic flysch. In this paper an engineering geological evaluation of the HDP is introduced. The field investigations included geological strip mapping, core drilling, and intense discontinuity surveying. A portion of the headrace tunnel was re-located due to adverse foundation conditions. The rock mass qualities of various lithological units were determined and the necessary support systems are described.     

Bend sensing with long-period fiber gratings in capillaries embedded in structures

Bend responses of an LPG inscribed with a CO₂ laser in a conventional single-mode fiber are investigated in an arrangement, where the LPG is inserted into a thin silica capillary bonded to a steel strip. The curvature of the strip, laid on two supports and bent with a micrometer driver in the middle between the supports, decreases linearly with distance from the center of bending to the supports. Experiments are done for a very large range of bend deflections with the LPG in three positions shifted with respect to the center of bending, and two distinct opposite rotational orientations with respect to the plane of bending. Responses obtained for the above positions and orientations are greatly different and some of them show features which have not been reported for LPGs bent with a constant curvature and smaller deflections. They are, particularly, maxima and minima of the central wavelength's shift along with reversals of its direction, or the reappearance of a previously vanished attenuation band with increasing magnitude of bending. Also, it is found that the responses depend not only on the average curvature of the bent LPG, but also on the particular dependence of the curvature along the LPG's length. Some of the results obtained cannot be satisfactorily explained at the present level of knowledge, and a more thorough theoretical analysis is needed.     

DNA electrochemical sensor based on conducting polymer: dependence of the "signal-on" detection on the probe sequence localization

We show in this work that it is possible to make selective direct electrochemical hybridization detection of a target strand onto a probe strand immobilized on a conducting polymer modified with a quinone group, which presents cation-exchange properties. This leads to a "signal-on"detection, a unique behavior in comparison to similar systems described in the literature. It is shown that this system is efficient for various probe and target lengths (10-30 bp) and can discriminate a single mismatch. To go further in comprehension of the detection mechanism, a systematic study of the electrochemical response versus the probe sequence localization onto the immobilized strand is performed. For example, a 30-bp target strand is divided into three shorter 10-bp sequences (A-C, respectively), and we investigate the successive hybridization of these 1/3 strands onto the 30-bp probe strand. It is shown that one probe strand can be used to address several shorter targets.     

Analyzing Global Dynamics of a Neural Field Model

We study global dynamics of the neural field, or a neural network model that represents densely distributed cortical neurons as a spatially continuous field. By analyzing the Lyapunov functional for the neural field with finite and infinite domains, we show that the state in the finite field necessarily converges to a steady solution and that the infinite field cannot have a limit cycle attractor. We also show that the Lyapunov functional of the neural field model can be considered to be a natural extension of the Lyapunov function of the Hopfield model to the continuous field. The result suggests that the two neural systems have, generally, common global dynamics characterized by the intimately related Lyapunov functional/function.     

State-based versus event-based specifications for information systems: a comparison of B and eb 3

This paper compares two formal methods, B and eb³, for specifying information systems. These two methods are chosen as examples of the state-based paradigm and the event-based paradigm, respectively. The paper considers four viewpoints: functional behavior expression, validation, verification, and evolution. Issues in expressing event ordering constraints, data integrity constraints, and modularity are thereby considered. A simple case study is used to illustrate the comparison, namely, a library management system. Two equivalent specifications are presented using each method. The paper concludes that B and eb³ are complementary. The former is better at expressing complex ordering and static data integrity constraints, whereas the latter provides a simpler, modular, explicit representation of dynamic constraints that are closer to the user’s point of view, while providing loosely coupled definitions of data attributes. The generality of these results from the state-based paradigm and the event-based paradigm perspective are discussed.     

Wide-band low noise MM-wave SIS mixers with a single tuning element

Several SIS quasiparticle mixers have been designed and tested for the frequency range from 80 to 115 GHz. The sliding backshort is the only adjustable RF tuning element. The RF filter reactance is used as a fixed RF matching element. A mixer which uses a single 2×2 μm² Pb-alloy junction in a quarter-height waveguide mount has a coupled conversion gain of G_M(DSB)=2.6±0.5 dB with an associated noise temperature of T_M(DSB)=16.4±1.8 K at the best DSB operation point. The receiver noise temperature T_R(DSB) is 27.5±0.8 K for the mixer test apparatus. This mixer provides a SSB receiver noise temperature below 50 K over the frequency range from 91 to 96 GHz, the minimum being T_R(SSB)=44±4 K. Another mixer with an array of five 5×5 μm² junctions in series in a full-height wave-guide mount has much lower noise temperature T_M(DSB)=6.6±1.6 K, but less gain G_M(DSB)=?5.1±0.5 dB.     

Renal excretion of xanthurenic acid as an index of vitamin B6 allowance in infants

Renal excretion of xanthurenic acid without any tryptophan load, passage of 4-pyridoxic acid with diurnal urine and its excretion with urine collected during 1 hour in the morning on an empty stomach were investigated in 86 practically healthy infants and in 77 others with acute respiratory viral infections aged from two weeks to one year. Investigations of the tryptophan tolerance in infants yielded negative results, viz. on administering to them of D,L-tryptophan in a load dose the infants started vomiting. Practically healthy infants did not excrete xanthurenic acid, while the renal excretion of 4-pyridoxic acid remained within normal limits. In patients at the height of the disease the passage of 4-pyridoxic acid steeply increased. In 9 of them xanthurenic acid appeared in the diurnal urine. In the quiscent stage of the affection in two infants xanthurenuria continued against the general background of diminished excretion of 4-pyridoxic acid. There is no reason to relate the disclosed xanthurenuria in sick infants with the state of hypovitaminosis in them.     

The sensitization of SrTiO3 photoanodes by doping with various transition metal ions

The influence that various dopants exert on the behaviour of single crystalline SrTiO₃ electrodes in a photoelectrochemical cell for water decomposition has been investigated. The electrodes were surface doped with Sr₃MeNb₂O₉ (Me₂₊ = Mn, Fe, Co, Ni) and LaMeO₃ (Me³⁺ = V, Cr, Mn, Fe, Co, Rh). The results have been compared with those for the sensitization of single crystalline SrTiO₃ photoanodes homogeneously doped with LaCrO₃ or the oxides of the transition metals Cr, Mn, Fe, Co, Ni, Nb, Mo, Ta and W. The response to visible light is greatest for Cr³⁺ and decreases in the sequence Co²⁺, Ni²⁺, Mn²⁺, Rh³⁺. The dopant ions V³⁺, Mn³⁺, Fe²⁺, Fe³⁺, Co³⁺ and the oxides of Nb, Mo, Ta and W reveal hardly any or no photosensitization. This is discussed in terms of a simple model proposed recently by members of our group.     

A new method for correcting axial dispersion in GPC

In this paper, a new method for correcting GPC results in order to take into account the axial dispersion of a given set of columns is proposed. The idea is to evaluate the different average molecular weights and the polydispersity for a given elution volume. In order to do so, one needs only to know the efficiency of the set of columns and the different derivatives at a given point of the chromatogram. Some possible applications of this method are reviewed mainly for the characterization of polydispersity and for the determination of the viscosity law if one uses the universal calibration.