Timing constraint specification and analysis

Real‐time programmers have to deal with the problem of relating timing constraints associated with source code to sequences of machine instructions. This paper describes an environment to assist users in the specification and analysis of timing constraints. A timing analyzer predicts the best and worst case bounds for these constrained portions of code. A user interface for this timing analyzer was developed to depict whether these constraints were violated or met. A user is allowed to specify timing constraints within the source code of a C program. The user interface also provides three different methods for interactively selecting portions of programs. After each selection the corresponding bounded times, source code lines, and machine instructions are automatically displayed. Users are prevented from only selecting portions of the program for which timing bounds cannot be obtained. In addition, a technique is presented that allows the timing analysis to scale efficiently with complex functions and loops. The result is a user‐friendly environment that supports the user specification and analysis of timing constraints at a high (source code) level and retains the accuracy of low (machine code) level analysis. Copyright © 1999 John Wiley & Sons, Ltd.     

Liberation of aldehydes from alk-1-enyl glyceryl ethers by acid hydrolysis

Labeled alk-1-enyl glyceryl ethers were used in conjunction with thin layer chromatography to study the liberation of aldehydes from alk-1-enyl glyceryl ethers by two acid hydrolysis procedures. Both methods gave similar results, but neither liberated the aldehydes quantitatively. Only 75–85% of the alk-1-enyl glyceryl ether radioactivity was liberated as free aldehydes. Several nonaldehyde products were detected and one appeared to be a cyclic acetal. Under contract with the U.S. Atomic Energy Commission.     

Effect of low-to-moderate amounts of dietary fish oil on neutrophil lipid composition and function

Although essential to host defense, neutrophils are also involved in numerous inflammatory disorders including rheumatoid arthritis. Dietary supplementation with relatively large amounts of fish oil [containing >2.6 g eicosapentaenoic acid (EPA) plus 1.4 g docosahexaenoic acid (DHA) per day] can attenuate neutrophil functions such as chemotaxis and superoxide radical production. In this study, the effects of more moderate supplementation with fish oil on neutrophil lipid composition and function were investigated. The rationale for using lower supplementary doses of fish oil was to avoid adverse gastrointestinal problems, which have been observed at high supplementary concentrations of fish oil. Healthy male volunteers aged <40 yr were randomly assigned to consume one of six dietary supplements daily for 12 wk (n=8 per treatment group). The dietary supplements included four different concentrations of fish oil (the most concentrated fish oil provided 0.58 g EPA plus 1.67 g DHA per day), linseed oil, and a placebo oil. The percentages of EPA and DHA increased (both P<0.05) in neutrophil phospholipids in a dose-dependent manner after 4 wk of supplementation with the three most concentrated fish oil supplements. No further increases in EPA or DHA levels were observed after 4 wk. The percentage of arachidonic acid in neutrophil phospholipids decreased (P<0.05) after 12 wk supplementation with the linseed oil supplement or the two most concentrated fish oil supplements. There were no significant changes in N-formyl-met-leu-phe-induced chemotaxis and superoxide radical production following the dietary supplementations. In conclusion, low-to-moderate amounts of dietary fish oil can be used to manipulate neutrophil fatty acid composition. However, this may not be accompanied by modulation of neutrophil functions such as chemotaxis and superoxide radical production.     

Dispersion tolerance of coherent WDM

We present the transmission of a 298.2-Gb/s copolarized coherent wavelength-division-multiplexing system over 80 km of standard single-mode fiber, achieving an information spectral density of 1 b/s/Hz with no prefilters at the transmitter. Odd and even tributary channels were encoded with data and delayed-data-bar pseudorandom binary sequence 2/sup 7/-1 patterns. The dispersion tolerance is investigated, and the dispersion penalty of this system is improved through adjustment of the relative phase of adjacent channels. Under optimum conditions, the dispersion penalty could be reduced from over 3 dB to less than 1 dB.     

Integrated bulk/SOI APD sensor: bulk substrate inspection with Geiger-mode avalanche photodiodes

A rapid assessment of bulk silicon quality after removal of the silicon-on-insulator (SOI) and buried oxide layer using both plasma and wet etch is compared with standard p-epi silicon by comparing the performance of avalanche photodiodes (APD) operated in Geiger-mode. Plasma etching of the buried oxide shows lower dark counts than wet etched or standard p-epi substrates.     

The meaning and management of neuroleptic medication: a study of patients with a diagnosis of schizophrenia

The meaning of medication and the way in which people use medicines has been the focus of a number of studies in recent years. However, there has been little attention directed to the meaning and management of neuroleptic medication by people who have received a diagnosis of schizophrenia. This topic is highly relevant to policy because of the central role given to neuroleptics in contemporary mental health and community care services. Using data from in-depth interviews with people with a diagnosis of schizophrenia we explore patients reasons for taking neuroleptics and the ways in which patients self-regulate their medication. The data suggest that the main utility of taking neuroleptic medication is to control specific symptoms and to gain personal control over managing symptoms. The costs of taking medication were side-effects which at times equalised or outweighed the positive gains of the neuroleptic medication. Patient accounts suggest that everyday medication practices are to a significant degree related to a policy context which stresses the need to survey and control the behaviour of people living in the community and the wider meaning and symbolic significance that schizophrenia has for patients in their everyday lives. For this reason, self regulatory action in this group of patients tends to be less evident and the threat of external social control greater than patients taking medication for other chronic conditions. The findings suggest the need to develop a collaborative patient-centred model of medication management for patients diagnosed with schizophrenia.     

Cytocompatibility of novel tin oxide thin films

The capacity of tin oxide films to support cell growth was investigated. Three substrates were used for the test: glass coverslips, glass coverslips spin coated with tin oxide and commercially available 316 stainless steel. The wettabilities and surface roughness of the three surfaces were measured before seeding 3T3 fibroblasts onto the samples. The behaviour of the cells grown on the tin oxide was compared to the uncoated glass and the steel and results showed that the cell growth on tin oxide compared favourably with the other substrates. The surface wettability appeared to have the strongest effect on cell adhesion to tin oxide.     

Packet Radio Performance Over Slow Rayleigh Fading Channels

Expressions for the throughput and average packet delay for a Pure-ALOHA single-hop packet radio system operating in slow Rayleigh fading are derived. For noncoherent frequency-shift-keying (NCFSK), an exact closed form expression is presented. For coherent phase-shift-keying (CPSK) an excellent approximation for large packet sizes is derived. This approximation technique is valid in general for other modulation schemes and for other fading channel statistical characterizations. The packet length which maximizes the useful data throughput in slow Rayleigh fading is found. The results of this investigation indicate that a packet radio system can be designed with a modest link margin for fading and achieve identical throughput performance over a nonfading channel and a fading channel with only a small increase in average packet delay for the fading channel.     

Retrospective trend analysis of the content of U.K. air particulate material 1957–1974

Particulate air samples have been collected on a daily basis in a high volume air sampler at Chilton (Oxfordshire U.K.) a semi-rural site in southern England from 1957 to 1974. Although the samples collected on esparto grass filters were intended to measure debris from nuclear weapons, they have proved susceptible to analysis for a variety of inorganic elements and ions.The concentration of twenty-seven elements and ions have been determined by instrumental neutron activation analysis and other methods. Measurements were performed on three-monthly groups of samples over seventeen years. Comparison with another series of current measurements over the latter part of the period indicate that the results are probably valid and thus, may represent the longest period for which continuous data of this nature are available. The detailed results are presented here.There are marked fluctuations in the levels displayed which can be categorised in three ways.There are seasonal changes. Winter levels, due either to increased emission rates or to meteorological phenomena, are greater than summer. The largest seasonal differences occur with chalcophilic (volatile) elements.Medium term fluctuations, in which excursions continue over extended periods, occur in similar ways with most constituents. A difference between the behaviour of anthropogenic and marine components indicate a meteorological mechanism for these changes. The most interesting changes are those showing long term trends. Many elements exhibit initial high levels with a rapid decline to 1961 and thereafter fall more slowly. The similarity of this behaviour with that of local “black smoke” indicates a component in the inorganic aerosol at Chilton from coal burning or industrial sources. The behavior of some lithophilic elements suggests an additional natural source.The behaviour of lead is consistent with a rise in emissions from petrol although there appears to be a residual component from other anthropogenic sources. A rise in bromine levels too, might be similarly explained.Vanadium appears to arise from the combustion of fuel oil now in increasing use.Concentrations of ammonium sulphate rise during the summers of the survey. It is likely that a photochemical mechanism for the production of sulphur dioxide oxidants from automobile exhaust is responsible. Similar photochemical processes and other reactions may cause the rises of ammonium nitrate although these display less seasonal bias.This survey at a single site demonstrates the value of data gathered over a long period, and emphasises the need to conduct controlled measurements for similar times at a variety of differing environmental and geographical locations.