Reliable microprocessor control for drive-by-wire car steering for the disabled

In a drive-by-wire steering system for the disabled driver, the safety of the system depends on the reliability of the electronic components. There is however another constraint, that of cost. A microprocessor-based system appears to be the most appropriate type. It was found however that three independent channels were needed to get the required level of reliability. The prototype system described here illustrates some of the problems and some of the potential solutions. Important among these is the balancing of the computations between the parallel channels.     

Correlation between specific adsorption and corrosion inhibition. Adsorption of 1-butylpyridinium bromide

A correlation between specific adsorption and corrosion inhibition was made on the basis of calculations of the degree of coverage at zero charge on the electrode and corrosion rates. 1-butylpyridinium bromide (BPB) was choosen as a model compound for these studies. The electrical double-layer parameters were determined at constant charge on a mercury electrode, from values of the interfacial capacity and surface tension obtained experimentally from aqueous solutions of BPB at 25° C. The characteristics of the salt as a corrosion inhibitor were studied through Tafel plots and weight-loss measurements using mild steel plates immersed in H₂SO₄ solutions. Analysis of the results lead to the conclusion that the salt adsorbs intensely on the metal surface, forming a complete monolayer of BP⁺ ions in 0.1 mol dm^–3 solutions and multilayers for higher concentrations. The results of this work indicate that for high coverages there is a good correlation between the amount of BP⁺ specifically adsorbed on mercury and the inhibition of the corrosion process on mild steel. That type of compound acts mainly as an anodic inhibitor in acid media by the formation of protective layers on the metal surface.     

Scaling and universality in continuous length combinatorial optimization

We consider combinatorial optimization problems defined over random ensembles and study how solution cost increases when the optimal solution undergoes a small perturbation delta. For the minimum spanning tree, the increase in cost scales as delta2. For the minimum matching and traveling salesman problems in dimension d >/= 2, the increase scales as delta3; this is observed in Monte Carlo simulations in d = 2, 3, 4 and in theoretical analysis of a mean-field model. We speculate that the scaling exponent could serve to classify combinatorial optimization problems of this general kind into a small number of distinct categories, similar to universality classes in statistical physics.     

A 1957 outbreak of Legionnaires' disease associated with a meat packing plant

Retrospective study shows that a 1957 outbreak of pneumonia in Austin, Minnesota, was Legionnaires' disease. Between June 7 and August 9, 1957, 78 persons were hospitalized with acute respiratory disease of unknown cause. Most had fever, headache, cough, and pneumonitis; two died. Ages ranged from 14-83 years; half of the patients were aged 55 years or older. Eighty-seven per cent were men. There were no secondary cases. Forty-six (59%) of the 78 patients were employees at a local meat packing plant, in distinction to the area's total working population (32%). Serosurvey of 15 of the 1957 outbreak cases and 30 controls matched for age, sex, and either occupation or residence was carried out in 1979. Antibody titers were determined for Legionella pneumophila serogroups 1-4 by means of indirect immunofluorescence. Twelve (80%) of the 15 cases and 13 (43%) of the 30 controls had antibody titers of 1:64 or greater to one or more of the L. pneumophila serogroups. Significant differences in L. pneumophila antibody titers (prevalence and level) were found between cases and control groups matched for residence (serogroups 1-3) or occupation (serogroups 2 and 3). Only three of 20 Austin residents with pneumonia diagnosed between 1978 and 1980 had L. pneumophila antibody titers of 1:128 or greater (p less than 0.001), in comparison to cases. These serologic data and the 1957 clinical and epidemiologic observations support the contention that this is the earliest documented outbreak of Legionnaires' disease.     

Immunoelectrophoretic analysis of the porcine zona pellucida

Antigens of the porcine zona pellucida were evaluated by 2-dimensional and line immunoelectrophoretic techniques. Zona antigen preparations studied included heat-solubilized isolated zonae pellucidae (SIZP), a purified 60 000 Mr glycoprotein (PPZA, purified pig zona antigen), and two fractions of this 60 000 Mr zona component which had been exposed to SDS (ZP3-E1C and ZP3-E2C). Antisera were raised to intact zonae pellucidae (IZP), SIZP and PPZA. Collectively, electrophoretic data revealed that the porcine zona system is antigenically complex with each zona antiserum tested detecting numerous antigens in the various zona preparations. These antigens, however, all had similar electrophoretic mobilities, and this limited the resolution of these techniques. The 60 000 Mr pig zona macromolecule (ZP3) appeared to be the most immunogenic of the three major pig zona glycoproteins since antisera prepared against IZP or SIZP reacted primarily with this component. However, the 60 000 Mr component does share antigenic determinants with the other major zona glycoproteins as revealed by cross-reactions of the antisera with the various zona preparations. Electrophoretic studies also suggested that the various zona antisera could distinguish, with different degrees of sensitivity, multiple antigenic determinants on the individual zona macromolecules. These studies also indicated that SDS treatment of zona glycoproteins does alter the antigenicity of the macromolecule, both with respect to the total number and individual identity of antigens detected.     

Ocular findings in patients with neutrophil dysfunction

Of 32 patients (19 females and 13 males, ranging in age from 2 to 44 years), nine had ocular problems related to neutrophil dysfunction. Four patients had blepharokeratoconjunctivitis and pannus formation. In one of these, severe visual loss secondary to corneal thinning and scarring occurred. Five patients had inactive chorioretinal scars without visual loss. Although some of the other 23 patients had minor ocular abnormalities, we could not demonstrate that they were related to the neutrophil dysfunction. However, none of the control subjects (20 patients with systemic lupus erythematosus and 20 randomly selected eye clinic patients) had lesions resembling those of the patients with neutrophil dysfunction. Fisher's exact test (one-tailed) gave the following values: P less than .03 for keratitis; P less than .01 for chorioretinal scars; and P less than .001 for keratitis and chorioretinal scars. Abnormal neutrophil function probably interferes with the control of normal eyelid flora and predisposes the eye to the development of marginal keratitis. Eyelid hygiene and topical administration of antibiotics and corticosteroids during inflammatory episodes may prevent the progression of corneal vascularization. The chorioretinal scars do not appear to be progressive.     

Studies of photon induced gas desorption using synchrotron radiation

In view of finalizing the design of the vacuum system of the Large Electron and Positron Storage Ring (LEP) we have studied synchrotron radiation induced neutral gas desorption. A 3 m section of an aluminum vacuum chamber has been exposed to the photon beam emerging from the electron storage ring DCI in Orsay, under conditions closely simulating the environment in a particle acceletor. In order of importance the gases desorbed were H₂, CO₂, CO and CH₄ with H₂O practically absent. Under the experimental conditions of an unbaked chamber and 11 mrad glancing incidence of the photons, the initial molecular desorption yields for these gases were typically 0.5, 8 × 10^?2, 2 × 10^?2 and 8 × 10^?3 molecules per photon respectively. These values could be reduced by about 1 to 2 orders of magnitude during continued photon exposure and most cases without evidence that this ‘beam cleaning action’ would be limited. After exposure to air and pumpdown of the previously cleaned chamber, we observe a significant memory effect. The dependence of the photon desorption on the angle of incidence has been studied down to a glancing angle of 11 mrad showing a definite deviation from the previously assumed 1/sin ø scaling. The implications of the results in terms of the expected beam-gas lifetime in LEP are discussed.     

Glyceryl trinitrate preparation (Suscard Buccal) causes caries and changes to the denture base material

Angina is the most common symptom of ischaemic heart disease and is frequently treated by the administration of nitrates. These three cases highlight dental sequelae of prolonged administration of sustained-release glyceryl trinitrate applied to the oral mucosa.     

Antibody-mediated neutralization of human rhinovirus 14 explored by means of cryoelectron microscopy and X-ray crystallography of virus-Fab complexes

The structures of three different human rhinovirus 14 (HRV14)-Fab complexes have been explored with X-ray crystallography and cryoelectron microscopy procedures. All three antibodies bind to the NIm-IA site of HRV14, which is the beta-B-beta-C loop of the viral capsid protein VP1. Two antibodies, Fab17-IA (Fab17) and Fab12-IA (Fab12), bind bivalently to the virion surface and strongly neutralize viral infectivity whereas Fab1-IA (Fab1) strongly aggregates and weakly neutralizes virions. The structures of the two classes of virion-Fab complexes clearly differ and correlate with observed binding neutralization differences. Fab17 and Fab12 bind in essentially identical, tangential orientations to the viral surface, which favors bidentate binding over icosahedral twofold axes. Fab1 binds in a more radial orientation that makes bidentate binding unlikely. Although the binding orientations of these two antibody groups differ, nearly identical charge interactions occur at all paratope-epitope interfaces. Nucleotide sequence comparisons suggest that Fab17 and Fab12 are from the same progenitor cell and that some of the differing residues contact the south wall of the receptor binding canyon that encircles each of the icosahedral fivefold vertices. All of the antibodies contact a significant proportion of the canyon region and directly overlap much of the receptor (intercellular adhesion molecule 1 [ICAM-1]) binding site. Fab1, however, does not contact the same residues on the upper south wall (the side facing away from fivefold axes) at the receptor binding region as do Fab12 and Fab17. All three antibodies cause some stabilization of HRV14 against pH-induced inactivation; thus, stabilization may be mediated by invariant contacts with the canyon.