Computer program simulates design, test, and analysis phases of sensitivity experiments

Modular program with a small main program and several specialized subroutines provides a general purpose computer program to simulate the design, test and analysis phases of sensitivity experiments. This program allows a wide range of design-response function combinations and the addition, deletion, or modification of subroutines

"Is there nothing more practical than a good theory?": Why innovations and advances in health behavior change will arise if interventions are used to test and refine theory

Theoretical and practical innovations are needed if we are to advance efforts to persuade and enable people to make healthy changes in their behavior. In this paper, I propose that progress in our understanding of and ability to promote health behavior change depends upon greater interdependence in the research activities undertaken by basic and applied behavioral scientists. In particular, both theorists and interventionists need to treat a theory as a dynamic entity whose form and value rests upon it being rigorously applied, tested and refined in both the laboratory and the field. To this end, greater advantage needs to be taken of the opportunities that interventions afford for theory-testing and, moreover, the data generated by these activities need to stimulate and inform efforts to revise, refine, or reject theoretical principles

Geometry of Valley Growth

Although amphitheater-shaped valley heads can be cut by groundwater flows emerging from springs, recent geological evidence suggests that other processes may also produce similar features, thus confounding the interpretations of such valley heads on Earth and Mars. To better understand the origin of this topographic form we combine field observations, laboratory experiments, analysis of a high-resolution topographic map, and mathematical theory to quantitatively characterize a class of physical phenomena that produce amphitheater-shaped heads. The resulting geometric growth equation accurately predicts the shape of decimeter-wide channels in laboratory experiments, 100-meter wide valleys in Florida and Idaho, and kilometer wide valleys on Mars. We find that whenever the processes shaping a landscape favor the growth of sharply protruding features, channels develop amphitheater-shaped heads with an aspect ratio of pi

Migraine, Fibromyalgia, and Depression among People with IBS: A Prevalence Study

BACKGROUND. Case descriptions suggest IBS patients are more likely to have other disorders, including migraine, fibromyalgia, and depression. We sought to examine the prevalence of these conditions in cohorts of people with and without IBS. METHODS. The source of data was a large U.S. health plan from January 1, 1996 though June 30, 2002. We identified all people with a medical claim associated with an ICD-9 code for IBS. A non-IBS cohort was a random sample of people with an ICD-9 code for routine medical care. In the cohorts, we identified all claims for migraine, depression, and fibromyalgia. We estimated the prevalence odds ratios (PORs) of each of the three conditions using the Mantel-Haenszel method. We conducted quantitative sensitivity analyses to quantify the impact of residual confounding and in differential outcome identification. RESULTS. We identified 97,593 people in the IBS cohort, and a random sample of 27,402 people to compose the non-IBS comparison cohort. With adjustment, there was a 60% higher odds in the IBS cohort of having any one of the three disorders relative to the comparison cohort (POR 1.6, 95% CI 1.5 – 1.7). There was a 40% higher odds of depression in the IBS cohort (POR 1.4, 95% CI 1.3 – 1.4). The PORs for fibromyalgia and migraine were similar (POR for fibromyalgia 1.8, 95% CI 1.7 – 1.9; POR for migraine 1.6, 95% CI 1.4 – 1.7). Differential prevalence of an unmeasured confounder, or imperfect sensitivity or specificity of outcome detection would have impacted the observed results. CONCLUSION. People in the IBS cohort had a 40% to 80% higher prevalence odds of migraine, fibromyalgia, and depression

miRNA-140-5p: new avenue for pulmonary arterial hypertension drug development?

Pulmonary arterial hypertension (PAH) is a rare but fatal disease. Pathologically, PAH is characterised by sustained vasoconstriction and progressive obliteration of small pulmonary arteries through a process of medial thickening, intimal fibrosis and the formation of angioproliferative lesions. Current treatments target the sustained vasoconstriction via either the prostacyclin, endothelin or nitric oxide pathway but do little to address the underlying progressive proliferative vascular disease. Dysregulated expression of microRNA (miR) has been identified in PAH and we have recently highlighted reduced miR-140-5p in patients with PAH. Replacement of miR-140-5p attenuated disease in animal models with the regulation of Smurf1, a E3 ubiquitin ligase targeting BMPR2 as one identified mechanism. These data highlight Smurf1 inhibition as a treatment for PAH

Erosion of a granular bed driven by laminar fluid flow

Motivated by examples of erosive incision of channels in sand, we investigate the motion of individual grains in a granular bed driven by a laminar fluid to give us new insights into the relationship between hydrodynamic stress and surface granular flow. A closed cell of rectangular cross-section is partially filled with glass beads and a constant fluid flux $Q$ flows through the cell. The refractive indices of the fluid and the glass beads are matched and the cell is illuminated with a laser sheet, allowing us to image individual beads. The bed erodes to a rest height $h_r$ which depends on $Q$. The Shields threshold criterion assumes that the non-dimensional ratio $\theta$ of the viscous stress on the bed to the hydrostatic pressure difference across a grain is sufficient to predict the granular flux. Furthermore, the Shields criterion states that the granular flux is non-zero only for $\theta >\theta_c$. We find that the Shields criterion describes the observed relationship $h_r \propto Q^{1/2}$ when the bed height is offset by approximately half a grain diameter. Introducing this offset in the estimation of $\theta$ yields a collapse of the measured Einstein number $q^*$ to a power-law function of $\theta - \theta_c$ with exponent $1.75 \pm 0.25$. The dynamics of the bed height relaxation are well described by the power law relationship between the granular flux and the bed stress.Comment: 12 pages, 5 figure

The impact of changing attitudes, norms, and self-efficacy on health-related intentions and behavior: a meta-analysis

Objective: Several health behavior theories converge on the hypothesis that attitudes, norms, and self-efficacy are important determinants of intentions and behavior. Yet inferences regarding the relation between these cognitions and intention or behavior rest largely on correlational data that preclude causal inferences. To determine whether changing attitudes, norms, or self-efficacy leads to changes in intentions and behavior, investigators need to randomly assign participants to a treatment that significantly increases the respective cognition relative to a control condition, and test for differences in subsequent intentions or behavior. The present review analyzed findings from 204 experimental tests that met these criteria. Methods: Studies were located using computerized searches and informal sources and meta-analyzed using STATA Version 11. Results: Experimentally induced changes in attitudes, norms, and self-efficacy all led to medium-sized changes in intention (d+ = .48, .49, and .51, respectively), and engendered small to medium-sized changes in behavior (attitudes-d+ = .38; norms-d+ = .36; self-efficacy-d+ = .47). These effect sizes generally were not qualified by the moderator variables examined (e.g., study quality, theoretical basis of the intervention, methodological characteristics, features of the targeted behavior), although effects were larger for interventions designed to increase (vs. decrease) behavioral performance. Conclusion: The present review lends novel, experimental support for key predictions from health behavior theories, and demonstrates that interventions that modify attitudes, norms, and self-efficacy are effective in promoting health behavior change

Computer simulations of domain growth and phase separation in two-dimensional binary immiscible fluids using dissipative particle dynamics

We investigate the dynamical behavior of binary fluid systems in two dimensions using dissipative particle dynamics. We find that following a symmetric quench the domain size R(t) grows with time t according to two distinct algebraic laws R(t) = t^n: at early times n = 1/2, while for later times n = 2/3. Following an asymmetric quench we observe only n = 1/2, and if momentum conservation is violated we see n = 1/3 at early times. Bubble simulations confirm the existence of a finite surface tension and the validity of Laplace's law. Our results are compared with similar simulations which have been performed previously using molecular dynamics, lattice-gas and lattice-Boltzmann automata, and Langevin dynamics. We conclude that dissipative particle dynamics is a promising method for simulating fluid properties in such systems.Comment: RevTeX; 22 pages, 5 low-resolution figures. For full-resolution figures, connect to http://www.tcm.phy.cam.ac.uk/~ken21/tension/tension.htm

Discussion: What Is a Replication?

Machery (2020) has recently proposed a "resampling" account of experimental replication to dissolve a debate in psychology about the relative merits of direct and conceptual replication. We argue that (i) on matters of replication’s function and typology, the resampling account is not substantially different from the functional account of replication extant in the literature; (ii) on what generalizations can be drawn from replications, the resampling account is too restrictive and relies on a misunderstanding of the relation between random sampling and generalizability; and (iii) Machery’s reading of the debate on the relative importance of direct and conceptual replication elides a deeper debate about values and the distribution of research resources in science