Energy metabolism in cochlear outer hair cells in vitro

ATP levels in outer hair cells in vitro were measured using the luciferin/luciferase method. Hair cells were isolated from the guinea pig cochlea and maintained for 2 h in a balanced salt solution with 5.5 mM glucose. Ten to 20 cells sufficed for a robust and reproducible luminescence signal, indicating an ATP content of 6.2 +/- 0.4 fmol/cell. This ATP concentration is similar to that found in cultures of other cell types and agrees well with the classical measurements in freeze-dried preparations. The ATP levels were reduced by the following treatments: (1) the omission of glucose in the culture medium lowered ATP levels by 28%; (2) the inhibition of glycolysis by 2-deoxyglucose lowered ATP levels by 66%; (3) the inhibition of oxidative phosphorylation by carbonyl cyanide m-chlorophenylhydrazine (CCCP) lowered ATP levels by 75%, and (4) the inhibition of both pathways reduced the ATP content to non-detectable levels. Acetoacetate was able to restore ATP levels partially when glycolysis was inhibited. These results suggest that (1) the major pathway of ATP synthesis in outer hair cells is the aerobic metabolism of glucose; (2) endogenous energy stores (e.g. glycogen) can maintain ATP levels in the absence of glucose; and (3) ketone bodies may be alternative energy sources.     

Calmodulin-dependent protein kinases mediate calcium-induced slow motility of mammalian outer hair cells

A sensitive, simple and rapid method without sample pretreatment is presented for the simultaneous determination of flunitrazepam and its main metabolites (norflunitrazepam, 7-amino- and 7-acetamidoflunitrazepam) in urine. The single-step procedure is based on a column-switching technique which uses an immobilized antibody in an extraction column following concentration on a precolumn and separation on an analytical column. UV detection was performed at 254 nm. The reusability of the antibody exceeds 88 runs and a complete analysis was performed in less than 40 min. The method shows coefficients of variation below 9.9% and rates of recovery greater than 92% tested at the level of 50 ng/ml urine. The limit of detection was below 2 ng/ml urine for the four compounds.     

Transforming flow information during code optimization for timing analysis

The steadily growing embedded-systems market comprises many application domains in which real-time constraints must be satisfied. To guarantee that these constraints are met, the analysis of the worst-case execution time (WCET) of software components is mandatory. In general WCET analysis needs additional control-flow information, which may be provided manually by the user or calculated automatically by program analysis. For flexibility and simplicity reasons it is desirable to specify the flow information at the same level at which the program is developed, i.e., at the source level. In contrast, to obtain precise WCET bounds the WCET analysis has to be performed at machine-code level. Mapping and transforming the flow information from the source-level down to the machine code, where flow information is used in the WCET analysis, is challenging, even more so if the compiler generates highly optimized code. In this article we present a method for transforming flow information from source code to machine code. To obtain a mapping that is safe and accurate, flow information is transformed in parallel to code transformations performed by an optimizing compiler. This mapping is not only useful for transforming manual code annotations but also if platform-independent flow information is automatically calculated at the source level. We show that our method can be applied to every type of semantics-preserving code transformation. The precision of this flow-information transformation allows its users to calculate tight WCET bounds.     

Blue-green algae toxicosis in cattle

Twenty-four of 175 heifers died after ingesting water from a stock pond containing blue-green algae (genus Microcystis) in southern Colorado. Affected cattle were found dead or had signs of nervousness, and were recumbent, weak, anorectic, and hypersensitive to noise when first examined. All cattle died within 3 days after the onset of signs. At necropsy, the rumen contained blue-green algae, and the liver was larger than normal, friable, and dark red. The most important histologic lesion was hepatocyte degeneration and necrosis. Intraperitoneal administration of lyophilized cell material from the bloom caused hepatic necrosis and death in mice, and water from the pond had clumps of cells surrounded by a clear calyx, consistent with the appearance of organisms of the genus Microcystis. Samples of pond water were examined by means of high-pressure liquid chromatography; microcystin-LR, one of the hepatotoxins produced by Microcystis spp, was found. Chromatography may be useful in the diagnosis of blue-green algae toxicosis.     

Calculating the maximum execution time of real-time programs

In real-time systems, the timing behavior is an important property of each task. It has to be guaranteed that the execution of a task does not take longer than the specified amount of time. Thus, a knowledge about the maximum execution time of programs is of utmost importance.This paper discusses the problems for the calculation of the maximum execution time (MAXT... MAximum eXecution Time). It shows the preconditions which have to be met before the MAXT of a task can be calculated. Rules for the MAXT calculation are described. Triggered by the observation that in most cases the calculated MAXT far exceeds the actual execution time, new language constructs are introduced. These constructs allow programmers to put into their programs more information about the behavior of the algorithms implemented and help to improve the self checking property of programs. As a consequence, the quality of MAXT calculations is improved significantly. In a realistic example, an improvement fator of 11 has been achieved.     

Real-Time Performance of Sorting Algorithms

In hard real-time systems tasks must meet their deadlines under guarantee. Soft real-time tasks may miss deadlines occasionally, as long as the entire system can provide the specified quality of service.In this paper we investigate the hard and soft real-time performance of sorting algorithms and compare it to their average performance. We show in which way the adequacy of an algorithm depends on the demanded performance criterium (hard, soft, or non real-time). The results provide a guideline to select the right sorting algorithm for a given application.     

Evaluating the Expressive Power of the Real-Time Specification for Java*

The goal of this paper is to evaluate the real-time specification for Java proposal by performing several case studies. These case studies include: an extensible general resource controller; atomic action support infrastructure; unbounded and imprecise computations. They have been used previously by the Ada community to evaluate the efficacy of the Ada concurrency and real-time models. Our results indicate that the Real-Time Specification for Java is expressive enough to cope with the demands of real-time concurrent programming. If it can be implemented efficiently, it will provide an alternative to Ada 95 for programming real-time systems.