From weakest-link to best-shot: The voluntary provision of public goods

It has traditionally been assumed that the socially available amount X of a public good is the simple sum of the separate amounts x _i produced by the i = 1, ..., I members of the community. But there are many other possibilities of practical importance. Among them are: (i) Weakest-link rule, where the socially available amount is the minimum of the quantities individually provided, and (ii) Best-shot rule, where the socially available amount is the maximum of the individual quantities. The former tends to arise in linear situations, where each individual has a veto on the total to be provided (e.g., if each is responsible for one link of a chain); the latter tends to arise when there is a single prize of overwhelming importance for the community, with any individual's effort having a chance of securing the prize. In comparison with the standard Summation formula of ordinary public-good theory, it is shown that underprovision of the public good tends to considerably moderated when the Weakest-link function is applicable, but aggravated when the Best-shot function is applicable. In time of disaster, where the survival of the community may depend upon each person's doing his duty, the conditions for applicability of the Weakest-link rule are approximated. This circumstance explains the historical observation that disaster conditions tend to elicit an extraordinary amount of unselfish behavior.     

Simple Bayesian Inference for Qualitative Political Research

In political science and related disciplines in the social andbehavioral sciences, there exists an unfortunate de facto dividebetween qualitative and quantitative empirical research. Sometimesthis divide is purely a function of training and disciplinarysocialization, but often it reflects a valid dispute over thephilosophical foundations of inquiry. I argue here that theBayesian approach to quantitative empirical modeling is an amenablestarting point for building a rapprochement between qualitativeand quantitative research, and I introduce as an example a straightforwardmodel that allows for the Bayesian estimation of the differencebetween means of very small samples with unknown and possiblyunequal variances. I then extend this approach to consider nonnormalvariates, informative priors, and a multivariate test of thedifference of means useful for the researcher who is interestedin determining whether two small samples are different on severaldimensions simultaneously.     

Weight force during prone restraint and respiratory function

Prone maximal restraint position (PMRP, also known as hogtie or hobble) is often used by law enforcement and prehospital personnel on violent combative individuals in the field setting. Weight force is often applied to the restrained individual's back and torso during the restraint process. We sought to determine the effect of 25 and 50 lbs weight force on respiratory function in human subject volunteers placed in the PMRP. We performed a randomized, cross-over, controlled trial on 10 subjects placed in 4 positions for 5 minutes each: sitting, PRMP, PRMP with 25 lbs weight force (PMRP+25), and PRMP with 50 lbs weight force placed on the back (PMRP+50). We measure pulse oximetry, end-tidal CO2 levels, and forced vital capacity (FVC) and forced expiratory volume in 1 second (FEV1). FVC and FEV1 were significantly lower in all restraint positions compared with sitting but not significantly different between restraint positions with and without weight force. Moreover, mean oxygen saturation levels were above 95% and mean end-tidal CO2 levels were below 45 mm Hg for all positions. We conclude that PMRP with and without 25 and 50 lbs of weight force resulted in a restrictive pulmonary function pattern but no evidence of hypoxia or hypoventilation.     

The quantification of fingerprint quality using a relative contrast index

Research into fingermark enhancement techniques has traditionally used visual comparisons and qualitative methods to assess their effectiveness based on the quality of the developed fingermark. However, with increasing research into the optimisation of these techniques the need for a quantitative evaluative method has arisen. Parameters for acceptable fingerprint quality are not well defined and generally encompass clear, sharp edges and high levels of contrast between the fingermark ridges and background material. Using these current parameters, a conclusive measurement of fingerprint quality and thus the effectiveness of development techniques cannot be achieved.This study presents a model through which an aspect of fingerprint quality can be objectively and impartially measured based on a relative contrast index, constructed through measuring the reflective intensity of the fingermark ridges against the background material. Using a fibre-optic spectrophotometer attached to a microscope with axial illumination, the intensity counts of the ridge detail and background material were measured and a logarithmic contrast index constructed. The microscope and spectrophotometer parameters were experimentally tested using a standard colour resolution chart with known reflective properties. The protocol was successfully applied to four sample groups: black inked fingerprints on white paper; latent fingermarks on white paper developed separately with ninhydrin and physical developer; and fingermarks in blood deposited on white tiles and enhanced with amido black. The contrast indices obtained quantitatively reflect the level of contrast and provide an indication of fingerprint quality through a numerical representation rather than previous qualitative methods. It has been suggested that the proposed method of fingerprint quantification may be viable for application in the forensic research arena as it allows the definitive measurement of contrast to aid the evaluation of fingermark detection and enhancement techniques.