Dissociation between the potency and reversibility of the insulinotropic action of two meglitinide analogues

The non-sulphonylurea hypoglycaemic agent repaglinide is about one order of magnitude less potent, in terms of insulinotropic efficiency, than S3075, another meglitinide analogue. In the present study, the effects of these two drugs upon 86Rb outflow, 45Ca efflux and insulin release from prelabelled rat pancreatic islets were investigated in a perifusion system. At a concentration of 10 microM, which is sufficient to evoke a maximal secretory response in incubated islets, both agents inhibited 86Rb efflux from islets perifused in the absence of D-glucose, and stimulated both 45Ca efflux and insulin release from islets perifused in the presence of 6 mM D-glucose. The stimulation of 45Ca efflux from prelabelled islets was suppressed in the absence of extracellular Ca2+. The cationic and secretory response to repaglinide differed, however, from that evoked by S3075, in persisting for at least 20 min after removal of the drug from the perifusion medium, whilst the changes in 86Rb outflow, 45Ca efflux and insulin release caused by S3075 were rapidly reversible. These findings indicate that there is no parallel between the insulinotropic efficiency of distinct meglitinide analogues, and the reversibility of their functional effects. Since a comparable dissociation was recently documented in the case of hypoglycaemic sulphonylureas, the present observations reinforce the view that distinct molecular determinants may rule the relative insulinotropic potency of sulphonylureas and structurally related meglitinide analogues, on one hand, and the reversibility of their biological action, on the other hand.     

Charge density dependence of elastic modulus of strong polyelectrolyte hydrogels

The mechanical behavior of a series of strong polyelectrolyte hydrogels based on acrylamide and 2-acrylamido-2-methylpropane sulfonic acid sodium salt (AMPS) was investigated. The hydrogels were prepared at a fixed crosslinker ratio and monomer concentration, but at various charge densities, i.e. AMPS contents between 0 and 100 mol%. The elastic modulus of the hydrogels after their preparation first increases with increasing charge density but then decreases continuously. Investigation of the swollen state properties of the hydrogels shows existence of a large number of ionic groups inside the gel that are ineffective in gel swelling. The results indicate two opposite effects of charged groups on the elastic modulus of the hydrogels: formation of multiplets acting as additional crosslinks in the gel increases the elastic modulus of ionic hydrogels, whereas the effect of the electrostatic interaction of charged groups on elastic free energy decreases the modulus.     

Fuzzy Bayesian reliability and availability analysis of production systems

To have effective production planning and control, it is necessary to calculate the reliability and availability of a production system as a whole. Considering only machine reliability in the calculations would most likely result unmet due dates. In this study, a new modelling approach for determining the reliability and availability of a production system is proposed by considering all the components of the system and their hierarchy in the system structure. Components of a production system are defined as production processes; components of the processes are defined as sub-processes. In this hierarchical structure we could model all kinds of failures such as material and supply, management and personnel, and machine and equipment. In the analysis, a fuzzy Bayesian method is used to quantify the uncertainties in the production environment. The suggested modelling approach is illustrated on an example. In the example, also a separate reliability and availability analysis is conducted which only considered machine failures, and the results of both analyses are compared.     

Mobile multi-view object image search

High user interaction capability of mobile devices can help improve the accuracy of mobile visual search systems. At query time, it is possible to capture multiple views of an object from different viewing angles and at different scales with the mobile device camera to obtain richer information about the object compared to a single view and hence return more accurate results. Motivated by this, we propose a new multi-view visual query model on multi-view object image databases for mobile visual search. Multi-view images of objects acquired by the mobile clients are processed and local features are sent to a server, which combines the query image representations with early/late fusion methods and returns the query results. We performed a comprehensive analysis of early and late fusion approaches using various similarity functions, on an existing single view and a new multi-view object image database. The experimental results show that multi-view search provides significantly better retrieval accuracy compared to traditional single view search.     

An adaptive least squares channel estimation based on conjugate gradient approach for multipath fading CDMA systems

Multiple access interference (MAI) is the main factor affecting the performance of channel estimation techniques for code division multiple access (CDMA) systems. Although, several multi-user channel estimation algorithms have been proposed to mitigate MAI, these algorithms require high computational complexities. In this paper, we address the problem of iterative least squares (LS) mobile channel estimation at high channel efficiency that requires a short training sequence along with the spreading sequences. We employ an efficient iterative method based on conjugate gradient (CG) algorithm to reduce the computational complexity of the estimation method. Computer simulations illustrate that the proposed method performs almost identical to the exact LS estimate for reasonable training lengths.     

Automated construction of fuzzy event sets and its application toactive databases

Fuzzy sets and fuzzy logic research aims to bridge the gap between the crisp world of maths and the real world. Fuzzy set theory was applied to many different areas, from control to databases. Sometimes the number of events in an event-driven system may become very high and unmanageable. Therefore, it is very useful to organize the events into fuzzy event sets also introducing the benefits of fuzzy set theory. All the events that have occurred in a system can be stored in event histories which contain precious hidden information. We propose a method for automated construction of fuzzy event sets out of event histories via data mining techniques. The useful information hidden in the event history is extracted into a matrix called sequential proximity matrix. This matrix shows the proximities of events and it is used for fuzzy rule execution via similarity based event detection and construction of fuzzy event sets. Our application platform is active databases. We describe how fuzzy event sets can be exploited for similarity based event detection and fuzzy rule execution in active database systems     

Multisecret-sharing schemes and bounded distance decoding of linear codes

Error-correcting codes are used to correct errors when messages are transmitted through a noisy communication channel. Bounded distance decoding (i.e. decoding up to the error-correcting capacity) is a method of correcting errors that guarantees unique decoding. Secret sharing is a cryptographic protocol that allows a secret known from a person called the dealer to be distributed to n participants. No single participant knows the secret but some special subsets of participants called coalitions can. In this paper, we present a multisecret-sharing scheme based on an error-correcting code where secret reconstruction is made by using bounded distance decoding of the code. This scheme is ideal in the sense that the size of each secret equals the size of any share. Its security improves on that of multisecret-sharing schemes.     

Study on the behavior of the trace metal and macro minerals in Mytilus galloprovincialis as a bioindicator species: the case of Marmara Sea, Turkey

Sea food is a major source of animal protein. Marine foods are very rich sources of mineral components. The total content of minerals in the raw flesh of marine fish and invertebrates is in the range of 0.6–1.5% wet weight. The contents of Na, K, Ca, Mg and P are up to 1 mg/100 g, whereas those of Fe, Zn, I are less than 1 mg/100 g. Mussels (Mytilus galloprovincialis) were investigated for macro and trace element composition throughout the year. Ranges of moisture, ash, protein and fat contents were 79.76–87.46 g/100 g, 1.06–2.06 g/100 g, 7.28–12.65 g/100 g and 0.33–3.49 g/100 g, respectively. While the highest protein and fat values were found in the summer (July–August), the highest moisture and ash contents were found in the winter (December–January). The contents of highest Na, K, Ca were found in the summer. Cadmium, lead and copper were found to be below the legislative limits throughout year. High levels of mercury were found in January and October. It should be discussed whether mussel may provide an alternative source of mineral for healthy nutrition.     

Inhomogeneities in poly(acrylamide) gels: position-dependent elastic modulus measurements

Summary The inhomogeneities in poly(acrylamide) (PAAm) gels and the formation mechanism of inhomogeneities were investigated using the results obtained by the mechanical measurements. The gels in the form of rods of 5.6 mm in diameter were prepared at various crosslinker (N,N'-methylene(bis)acrylamide) content. The initial monomer concentration was set to 5.1 w/v %. The results show that the elastic modulus of PAAm gels varies depending on the location, at which the mechanical measurements are carried out. The modulus increases with increasing distance from the bottom of the gel rod. The extent of modulus variation along the gel increases with increasing crosslinker content from 2.6 to 9 % BAAm. Received: 23 January 2001/Revised version: 17 May 2001/Accepted: 17 May 2001     

Magnetic Properties of Zn1?x Ni x O (0.25≤x≤ 0.50) Prepared by Solid-State Reactions

In this study the origin of ferromagnetism in ZnO-based bulk systems has been investigated using Ni-doped ZnO samples, Zn_1−x Ni _x O with 0.25≤x≤0.50, prepared by solid-state reactions. The structural characterizations indicated that the Ni²⁺ ions almost uniformly distributed in all the samples, and the samples have hexagonal wurtzite structure; however, when x is increased toward 0.50, a new NiO phase is formed. A ferromagnetism (FM) has been observed for all the samples at and below the room temperature. In other words, the room temperature results of (M–H) curves show that the FM observed is intrinsic for all the Ni-doped ZnO samples. However, the saturated magnetizations decrease gradually with increasing Ni concentration. This indicates that, in addition to FM, the excessive doping of Ni in ZnO also causes an antiferromagnetic (AFM) contribution which increases with increasing Ni amount. This result is also supported by the magnetization against temperature measurements. Furthermore, the trend of the ac-susceptibility (χ) versus temperature curves, measured under an ac-magnetic field of 100 Oe, also support our conclusion about the antiferromagnetic contribution to ferromagnetism in our samples.