Boolean regression

We take a regression-based approach to the problem of induction, which is the problem of inferring general rules from specific instances. Whereas traditional regression analysis fits a numerical formula to data, we fit a logical formula to boolean data. We can, for instance, construct an expert system for fitting rules to an expert's observed behavior. A regression-based approach has the advantage of providing tests of statistical significance as well as other tools of regression analysis. Our approach can be extended to nonboolean discrete data, and we argue that it is better suited to rule construction than logit and other types of categorical data analysis. We find maximum likelihood and bayesian estimates of a best-fitting boolean function or formula and show that bayesian estimates are more appropriate. We also derive confidence and significance levels. We show that finding the best-fitting logical formula is a pseudo-boolean optimization problem, and finding the best-fitting monotone function is a network flow problem.The first and second authors gratefully acknowledge the partial support of NSF (Grant DMS 89-06870) and AFOSR (Grants 89-0512 and 90-0008), and the third author that of AFOSR (Grant 91-0287) and ONR (Grant N00014-92-J-1028).     

Laser-excited nonlinear properties of BaF2 and its application in a single-shot spatially insensitive autocorrelator

A detailed investigation of laser-generated nonlinear processes of undoped barium fluoride is presented including two-photon-excited exciton fluorescence, color-center formation and damage-threshold measurements. A single-shot autocorrelator based on two-photon fluorescence of BaF₂ was constructed to measure the phase and amplitude of pulses provided by large apeture excimer lasers. The capabilities of the autocorrelator are demonstrated at 248 nm and 268 nm with pulses in the regime of 100 fs to 10 ps.     

Transverse interferometry of a hydrogen-filled capillary discharge waveguide

Transverse interferometric measurements are presented of the plasma channel formed in a hydrogen-filled capillary discharge waveguide recently used to generate 1 GeV electrons in a laser-driven plasma accelerator for the first time. The measurements were found to be in good agreement with nonlocal thermal equilibrium simulations, but showed significant differences with the results of a quasistatic model developed by Bobrova et al. [Phys. Rev. E. 65, 016407 (2001)]. The measurements are used to determine scaling laws for the axial electron density and matched spot size of the plasma channel, enabling optimization of the channel to specific applications.     

Familial aggregation of early-onset myocardial infarction

Although ischemic heart disease tends to cluster in families, previous studies have reported a modest (2-fold increased risk) to strong (10-fold increased risk) contribution of family history to the explanation of disease occurrence. The authors assessed the familial aggregation of early-onset myocardial infarction in 11,307 adults aged <65 years who participated in the Third National Health and Nutrition Examination Survey. Logistic regression was used to obtain odds ratios (ORs) and 95% confidence intervals (CIs). A parental history was more common in those with (n = 237) than in those without (n = 11,070) a myocardial infarction (19.8 vs. 7.9%, p < or = 0.01). Adults with a parental history were also more likely to have multiple risk factors for cardiovascular disease (OR for four or five risk factors compared with none: 2.9, 95% CI: 1.4, 6.3). After multivariate adjustment, the likelihood of myocardial infarction was more than three times greater among adults with a parental history than among those without (95% CI: 1.7, 6.7). A maternal history of myocardial infarction was strongly associated (OR = 6.1, 95% CI: 2.1, 17.4) with an increased likelihood of myocardial infarction, and a paternal history was associated with a 3-fold (95% CI: 1.5, 6.3) increased likelihood of myocardial infarction after adjustment for cardiovascular disease risk factors. These results suggest a familial aggregation of early-onset myocardial infarction and show that family history is strongly associated with cardiovascular disease risk factors.     

A versatile and modular approach to functionalisation of deep-cavity cavitands via"click" chemistry

The surface modification of deep-cavity cavitands has been demonstrated by using the azide-alkyne "click" coupling to attach dendritic macromolecules or linear polymers onto their periphery. The resulting set of macromolecular cavitands exhibited tuneable solubility yet retained the ability to encapsulate guest molecules.     

Infra-red spectrum,structure and properties of the N2-Ar van der Waals molecule

The first spectroscopic observation of bound N₂-Ar van der Waals molecules has been achieved with a cryogenic long path cell maintained at 87 K. The infra-red spectrum exhibits prominent fine structure near the N₂ stretching frequency which is assigned to hindered internal rotation of N₂ within the weakly bound complex. An analysis of this fine structure yields a T-shaped equilibrium geometry in which the N₂ bond axis is perpendicular to the N₂-Ar van der Waals bond axis. The observed spectrum is shown to be consistent with an internal rotational barrier of 20 cm^-1 (57 cal/mole). Approximately 20 per cent of the bound species are trapped by this rotational barrier and acquire a locked semi-rigid structure. The remaining 80 per cent have ill-defined geometry and undergo hindered internal rotation. The rotational envelope of an infra-red fundamental is analysed to give an estimate of the N₂-Ar bond length as 3·9 Å.     

Bei der Bestimmung der schwefligen S?ure in ihren Verbindungen

Ohne Zusammenfassung     

Ueber die Analogie des Verhaltens von Emulsionen und des Verhaltens von Fett im Protoplasma

Ohne Zusammenfassung Uebersetzt von J. Matula (Wien). Eine vorl?ufige Mitteilung der in dieser und einer vorhergehenden in dieser Zeitschrift erschienenen Abhandlung niedergelegten Ergebnisse erschien in Science43 (1916).     

Die Schmelz- und Sättigungskurven der binären Systeme: Substituierte Benzoesäuren und Wasser

Ohne Zusammenfassung