Two by McCormick

Book reviewed in this article: How Brave a New World? Dilemmas in Bioethics . By Richard A. McCormick. Notes on Moral Theology, 1965 through 1980 . By Richard A. McCormick.     

Sculpting of an erodible body by flowing water

Erosion by flowing fluids carves striking landforms on Earth and also provides important clues to the past and present environments of other worlds. In these processes, solid boundaries both influence and are shaped by the surrounding fluid, but the emergence of morphology as a result of this interaction is not well understood. We study the coevolution of shape and flow in the context of erodible bodies molded from clay and immersed in a fast, unidirectional water flow. Although commonly viewed as a smoothing process, we find that erosion sculpts pointed and cornerlike features that persist as the solid shrinks. We explain these observations using flow visualization and a fluid mechanical model in which the surface shear stress dictates the rate of material removal. Experiments and simulations show that this interaction ultimately leads to self-similarly receding boundaries and a unique front surface characterized by nearly uniform shear stress. This tendency toward conformity of stress offers a principle for understanding erosion in more complex geometries and flows, such as those present in nature.     

Cannabis,Cigarettes, and Their Co-Occurring Use: Disentangling Differences in Gray Matter Volume

Background:

Structural magnetic resonance imaging techniques are powerful tools for examining the effects of drug use on the brain. The nicotine and cannabis literature has demonstrated differences between nicotine cigarette smokers and cannabis users compared to controls in brain structure; however, less is known about the effects of co-occurring cannabis and tobacco use.

Methods:

We used voxel-based morphometry to examine gray matter volume differences between four groups: (1) cannabis-dependent individuals who do not smoke tobacco (Cs); (2) cannabis-dependent individuals who smoke tobacco (CTs); (3) cannabis-naïve, nicotine-dependent individuals who smoke tobacco (Ts); and (4) healthy controls (HCs). We also explored associations between gray matter volume and measures of cannabis and tobacco use.

Results:

A significant group effect was observed in the left putamen, thalamus, right precentral gyrus, and left cerebellum. Compared to HCs, the Cs, CTs, and Ts exhibited larger gray matter volumes in the left putamen. Cs also had larger gray matter volume than HCs in the right precentral gyrus. Cs and CTs exhibited smaller gray matter volume than HCs in the thalamus, and CTs and Ts had smaller left cerebellar gray matter volume than HCs.

Conclusions:

This study extends previous research that independently examined the effects of cannabis or tobacco use on brain structure by including an examination of co-occurring cannabis and tobacco use, and provides evidence that cannabis and tobacco exposure are associated with alterations in brain regions associated with addiction.     

Extending Physician ReACH: Influencing patient activation and behavior through multichannel physician communication

Objective

Despite evidence-based recommendations, physical activity as a self-management technique is underutilized. Many physical activity interventions require significant resources, ranging from repeated phone follow-up with nursing staff to intensive sessions with cooperating physical therapists. This intervention, Extending Physician ReACH (Relationship And Communication in Healthcare), examined physician to patient communication tactics for promoting walking exercise to patients with type 2 diabetes, using limited clinic time and financial resources.

Methods

This was a single-site, six-month prospective intervention, which implemented theoretically driven, evidenced-based information factor strategies. Of the 128 volunteers who participated in the initial clinic visit, 67 patients with type 2 diabetes completed the six-month intervention.

Results

Significant intervention effects were detected risk perception, social norms, and patient activation.

Conclusions

This study was designed to identify information factors that could affect physician success in motivating patients with type 2 diabetes to enact the ADA physical activity recommendations.

Practice implications

The success of this intervention models a strategy through which clinicians can reach beyond “one-shot” persuasion without placing onerous time and resource demands on physicians.