Effects of Al3+ and Be2+ ions combined with NaF on ciliary process adenylyl cyclase activity and aqueous humor dynamics in the rabbit eye

PURPOSE: The activity of Al3+, Ga3+, and Be2+ ions in the presence of NaF to directly activate G-proteins was investigated by their potentiative effect on forskolin (FSK)-activated adenylyl cyclase in rabbit ciliary process membranes and their effects on aqueous humor dynamics in vivo. METHODS: Adenylyl cyclase (AC) was determined by radiometric conversion of ATP to cAMP by the particulate fraction of rabbit ciliary processes. Intravitreal injections of sterile solutions of analytical grade salts were made into the center of the vitreous in a volume of 20 microliters. Intraocular pressure, aqueous humor flow, and uveoscleral outflow measurements were made by pneumatonometry, fluorophotometry, and fluorescein-dextran method, respectively. Outflow facility was determined by tonography in the intact eyes and by two-level constant pressure perfusion in cannulated eyes. RESULTS: Both Al3+ (EC50, 40 mumol/l) and Be2+ (EC50, 11 mumol/l) in the presence of 0.5-2 mM NaF activated the stimulatory G-protein Gs. Ga3+ was ineffective and did not antagonize the activation by Al3+. Intravitreal injections of Al3+ (1 mumol/eye) or Be2+ (0.5 or 1 mumol/eye) had no significant intraocular pressure (IOP) effect, nor did 1.5 or 3 mumol/eye of NaF, but when either cation was injected together with NaF, IOP decreased by up to 40% for up to 140 hr. At the time of maximum IOP effect (72 hr) aqueous humor flow determined by fluorophotometry was decreased in BeCl2+ NaF-treated eyes by 40% relative to BeCl2-treated eyes; however, tonographic facility of outflow was unaffected. Uveoscleral flow was also decreased by 38% in BeCl2+ NaF treated eyes. CONCLUSIONS: These findings support the hypothesis that Gs activation of ciliary process adenylyl cyclase decreases aqueous humor formation rate in rabbit eyes, and that activation of G-proteins mediates contraction of ciliary muscles causing a decrease of aqueous humor outflow via the uveoscleral route. The results suggest that G-proteins putatively involved in trabecular facility changes are less sensitive to activation by BeF3- than are other parameters of aqueous humor dynamics.     

Field observations on the occurrence of new indicators of disinfection efficiency

This paper summarizes studies on the presence of acid-fast and yeast organisms in wastewater and water treatment plants and in surface water. These organisms were found to satisfy three of Bonde's criteria for indicator organisms: presence whenever pathogens are likely to be present; resistance at least equal to that of pathogens; and lack of regrowth in the post-treatment environment. This, plus prior data, indicates that these organisms are at least as acceptable as indicators of disinfection efficiency than the coliform group.     

Über die Bildung des Kakaoaromas aus seinen Vorstufen

Formation of Cocoa Aroma from Its Precursors Isolation and chemical composition of a highly purified mixture of aroma-precursors from raw cocoa were extensively studied and the alterations due to heating at roasting temperatures were followed quantitatively. Cocoa aroma is formed in the course of a Maillard reaction between amino acids and reducing sugars. Participation of oligopeptides in the alterations that are specific for the process of roasting could be detected for the first time. From the high-boiling components present in the reaction product, a fraction having the typical cocoa flavour could be isolated and resolved by gas chromatography. The consequences of these observations on the technology of roasting of cocoa are discussed.     

Unerwünschte Reaktionen organischer Stoffe als Gefahren in Chemieanlagen

Undesired reactions of organic substances as sources of danger in chemical plant . In chemical production processes, danger can arise both from the intended exothermal reaction and from unintended exothermal reactions. Such “undesired” reactions may be exothermal reactions of the substances themselves (e.g. decomposition, polymerization) or reactions of the substances involved with one another (e. g. of a reactant with the solvent). Differential thermal analysis and warm storage have been successfully used in various modifications as experimental methods for the study of such reactions. For exothermal decomposition reactions, correlations can be made between the chemical constitution of the substances and the energy released on decomposition, as well as the temperature of incipient decomposition. In mixtures with other substances a modified decomposition behaviour must be expected, usually of such a kind that the temperature range of decomposition is lowered. There are many possible exothermal reactions of substances with one another; only a few have hitherto been studied in detail.     

Dealing with midair collisions in dense collective aerial systems

The idea of creating collective aerial systems is appealing because several rather simple flying vehicles could join forces to cover a large area in little time in applications such as monitoring, mapping, search and rescue, or airborne communication relays. In most of these scenarios, a fleet of cooperating vehicles is dispatched to a confined airspace area and requested to fly close to a nominal altitude. Moreover, depending on the task each vehicle is assigned to, individual flight trajectories in this essentially two‐dimensional space may interfere, resulting in disastrous collisions. This paper begins by introducing a probabilistic model to predict the rate of midair collisions that would occur if nothing is done to prevent them. In a second step, a control strategy for midair collision avoidance is proposed, which is interesting because it requires only local communication and information about flight altitudes. The proposed strategy is systematically analyzed in theory and simulation as well as in experiments with five physical aerial vehicles. A significant reduction in collision rates can be achieved. Statistically, values close to zero are possible when the swarm's density is below an application‐dependent threshold. Such low collision rates warrant an acceptable level of confidence in collision‐free operation of a physical swarm. © 2011 Wiley Periodicals, Inc.     

An effective heuristic for adaptive control of job sequences subject to variation in processing times

Variation in sequential task processing times is common in manufacturing systems. This type of disturbance challenges most scheduling methods since they cannot fundamentally change job sequences to adaptively control production performance as jobs enter the system because actual processing times, are not known in advance. Some research literature indicates that simple rules are more suitable than algorithmic scheduling methods for adaptive control. In this work, a ‘state space – average processing time’ (SS-APT) heuristic is proposed and compared to four most commonly used scheduling rules and two well-established heuristics based on Taillard’s benchmarks. It is shown that the adaptive control is made possible under variation in processing times given the flexibility and strong performance of the SS-APT heuristic, especially for work-in-process inventory control.     

Hyperwelcome

Web page annotation and adaptive navigation support are two active, but independent research directions focused on the same goal: expanding the functionality of the Web as a hypertext system. The goal of the AnnotatEd system presented in this paper has been to integrate annotation and adaptive navigation support into a single value-added service where the components can reinforce each other and create new unique attributes. This paper describes the implementation of AnnotatEd from early prototypes to the current version, which has been explored in several contexts. We summarize some lessons we learned during the development process and which defined the current functionality of the system. We also present the results of several classroom studies of the system. These results demonstrate the importance of the browsing-based information access supported by AnnotatEd and the value of both the annotation and navigation support functionalities offered by the system.     

Nanotextures of composites based on the interaction between hydroxyapatite and cellulose Gluconacetobacter xylinus

Organic-inorganic composite materials with different nanotextures have been prepared using three methods based on two nanosized and biocompatible compounds—cellulose Gluconacetobacter xylinus (CGX) and hydroxyapatite Ca₅(PO₄)₃OH (HA). The structure of the initial components and their composites has been studied using the methods of X-ray diffraction, electron microscopy, and computer simulation. During the combined aggregation of aqueous HA and CGX suspensions, the phenomenon of their adsorption, in the process of which the axis c of HA crystals is oriented parallel to the plane (?110) of CGX microfibrillas, was observed. By varying the quantitative ratio of the components and the methods of introducing HA into composites, it is possible to obtain a wide spectrum of materials for medical practice.