Can Indirect Causation be Real?

Causal realists maintain that the causal relation consists in “something more” than its relata. Specifying this relation in nonreductive terms is however notoriously difficult. Michael Tooley has advanced a plausible account avoiding some of the relation’s most obvious difficulties, particularly where these concern the notion of a cross-temporal “connection.” His account distinguishes discrete from nondiscrete causation, where the latter is suitable to the continuity of cross-temporal causation. I argue, however, that such accounts face conceptual difficulties dating from Zeno’s time. A Bergsonian resolution of these difficulties appears to entail that, for the causal realist, there can be no indirect causal relations of the sort envisioned by Tooley. A consequence of this discussion is that the causal realist must conceive all causal relations as ultimately direct.     

Apparent molar volumes of aqueous calcium chloride to 250°C, 400 bars,and from molalities of 0.242 to 6.150

Relative densities of CaCl ₂ (aq) with 0.22ml(mol-kg^–1)6.150 were measured with vibrating- tube densimeters between 25 and 250°C and near 70 and 400 bars. Apparent molar volumes V calculated from the measured density differences were represented with the Pitzer ioninteraction treatment, with appropriate expressions chosen for the temperature and pressure dependence of the virial coefficients of the model. It was found that the partial molar volume at infinite dilution V ^o , and the second and third virial coefficients B ^V and C ^V , were necessary to represent V near the estimated experimental uncertainty. The ionic-strength dependent ^(1)v term in the B ^V coefficient was included in the fit. The representation for V has been integrated with respect to pressure to establish the pressure dependence of excess free energies over the temperature range studied. The volumetric data indicate that the logarithm of the mean ionic activity coefficient, ln ±(CaCl ₂ ), increases by a maximum of 0.3 at 400 bars, 250°C, and 6 mol-kg^–1 as compared with its value at saturation pressure.     

Cu-DNAzyme facilitates highly sensitive immunoassay

A simple Cu-DNAzyme system is used for signal transduction of a CuO nanoparticle-labeled immunoassay, which makes the immunoassay fast, simple, cost-effective, and sensitive, thus promising for biomedical applications and point-of-care testing.     

Computer simulation model for the prediction of traffic noise levels

This paper describes a computer simulation model capable of predicting the noise levels generated by traffic passing through road intersections controlled by roundabouts where departures from free-flow traffic conditions occur. The model depends for its operation on the acoustical and flow characteristics of single vehicles travelling on a road from which the overall noise generated by traffic streams can be deduced using a sampling/integration technique. Distance effects, ground cover, vehicle type, velocity and headway characteristics, etc. are taken into account in the model and the simplest possible input parameters are used deliberately to facilitate the eventual use of the model by highway and planning authorities. Good agreement has been achieved between measured and predicted L₁₀ values for freely flowing traffic negotiating roundabouts. Further applications of the model involving road intersections controlled by traffic lights and the effect of traffic queues are nearing completion.     

Survival analysis

Statistical methods for the analysis of times to failure have developed rapidly in the past decade. Model for their dependence on explanatory variables such as the working temperature, the stress exerted and the wear sustained can be formulated and the relevant parameters in these models estimated from data, without restrictive assumptions as to distributional form. This survey, while far from comprehensive, discusses those aspects of the theory which in the author's opinion are of most relevance to the practitioner. Most of the review concerns destructive (nonrepairable) failure of single units, but some attention is given also to the analysis of multiple failures, possibly of differing types.