Simultaneous interferometric measurement of corrosive or demineralizing bacteria and their mineral interfaces.

Here, we report simultaneous surface profile measurements of several bacterial species involved in microbially influenced corrosion and their solid-surface interfaces by using vertical scanning interferometry. The capacity to nondestructively quantify microscale topographic changes beneath a single bacterium without its removal offers a unique opportunity to examine in vivo microbe-surface interactions.

In search of the microbe/mineral interface: quantitative analysis of bacteria on metal surfaces using vertical scanning interferometry.

To understand the development of biofilms on metal surfaces, analysis of initial bacterial attachment to surfaces is crucial. Here we present the results of a study, using Shewanella oneidensis MR-1 as a model organism, in which vertical scanning interferometry (VSI) was used to investigate the initial stages of cell attachment to glass, steel and aluminium surfaces. It was found that while VSI gave unambiguous results with opaque surfaces, when reflective surfaces were used, an artifact sometimes appeared, with the bacteria appearing as rod-shaped pits rather than as cells on the surface. When the bacteria were altered to increase opacity, this artifact disappeared, and upon further investigation, it was found that the observational artifact was the result of a conflict between light reflected from the bacteria and the light reflected from the bacteria-metal interface. These results suggest that not only can bacteria be measured on surfaces using VSI, but with some modifications to the analytical software, there may be a unique window for studying the bacterial/substrate interface that can be used for quantitative observations. Imaging and characterization of the bacteria-substrate interface in vivo (previously invisible) will provide new insights into the interactions that occur at this important juncture.

The "bathroom game": a systematic program for the elimination of encopretic behavior.

The present investigation utilized a unique, variable ratio schedule of reinforcement (the "bathroom game") to treat a 10-year-old encopretic male. Dependent measures included confirmed incidents of (a) soiling and (b) appropriate bowel movements monitored across an ABAB design (Baseline 1, "Bathroom Game 1", Baseline 2, "Bathroom Game 2") with one-year follow-up. During "bathroom game" conditions, contingent monetary rewards were provided for non-instances of soiling and appropriate bowel movements. Such rewards were progressively and systematically leaned-out over the course of treatment on a pre-determined variable ratio schedule. Results indicated a clear demonstration of functional control and clinically significant treatment effects during both experimental periods. These findings are discussed with regard to the positive features of the "bathroom game" procedure and recommendations are made for future investigations in the area.

Paradoxical instruction in the treatment of encopresis and chronic constipation: an experimental analysis.

The purpose of the present single-case experimental investigation was to examine the efficacy of paradoxical instruction in the treatment of exacerbation-based discontinuous encopresis and chronic constipation. The subject, a 9-yr old male, complained of infrequent bowel movements and daily soiling. In addition, toileting and related activities appeared to cause considerable anxiety. An ABAB reversal design with 1-yr follow-up was used as a means of evaluating treatment effectiveness. Dependent measures included weekly parental records of soiling and appropriate bowel movements. Results indicated a clear demonstration of functional control and consistent improvement in the encopretic disturbance. These findings were maintained at 1-yr follow-up.