Genetics of adaptation: Experimental test of a biotic mechanism driving divergence in traits and genes.

The genes underlying adaptations are becoming known, yet the causes of selection on genes-a key step in the study of the genetics of adaptation-remains uncertain. We address this issue experimentally in a threespine stickleback species pair showing exaggerated divergence in bony defensive armor in association with competition-driven character displacement. We used semi-natural ponds to test the role of a native predator in causing divergent evolution of armor and two known underlying genes. Predator presence/absence altered selection on dorsal spines and allele frequencies at the Msx2a gene across a generation. Evolutionary trajectories of alleles at a second gene, Pitx1, and the pelvic spine trait it controls, were more variable. Our experiment demonstrates how manipulation of putative selective agents helps to identify causes of evolutionary divergence at key genes, rule out phenotypic plasticity as a sole determinant of phenotypic differences, and eliminate reliance on fitness surrogates. Divergence of predation regimes in sympatric stickleback is associated with coevolution in response to resource competition, implying a cascade of biotic interactions driving species divergence. We suggest that as divergence proceeds, an increasing number of biotic interactions generate divergent selection, causing more evolution in turn. In this way, biotic adaptation perpetuates species divergence through time during adaptive radiation in an expanding number of traits and genes

A reduced-order model of three-dimensional unsteady flow in a cavity based on the resolvent operator

A novel reduced-order model for nonlinear flows is presented. The model arises from a resolvent decomposition in which the nonlinear advection terms of the Navier-Stokes equation are considered as the input to a linear system in Fourier space. Results show that Taylor-G\"ortler-like vortices can be represented from a low-order resolvent decomposition of a nonlinear lid-driven cavity flow. The present approach provides an approximation of the fluctuating velocity given the time-mean and the time history of a single velocity probe

Steady streamwise transpiration control in turbulent pipe flow

A study of the the main features of low- and high amplitude steady streamwise wall transpiration applied to pipe flow is presented. The effect of the two transpiration parameters, amplitude and wavenumber, on the flow have been investigated by means of direct numerical simulation at a moderate turbulent Reynolds number. The behaviour of the three identified mechanisms that act in the flow: modification of Reynolds shear stress, steady streaming and generation of non-zero mean streamwise gradients, have been linked to the transpiration parameters. The observed trends have permitted the identification of wall transpiration configurations able to reduce or increase the overall flow rate in -36.1% and 19.3% respectively. A resolvent analysis has been carried out to obtain a description of the reorganization of the flow structures induced by the transpiration

Occupational Therapists as Street-Level Bureaucrats: Leveraging the Political Nature of Everyday Practice.

BACKGROUND.: As front-line service providers who often work in systems regulated by governmental bodies, occupational therapists can be conceptualized as street-level bureaucrats ( Lipsky, 1980/2010 ) who effect and are affected by policy. PURPOSE.: Drawing on understandings from a study of long-term unemployment, this article proposes that occupational therapists, as street-level bureaucrats, respond to inter-related policies and systems in ways that can perpetuate, resist, or transform opportunities for doing and being. KEY ISSUES.: By highlighting practitioners\u27 everyday negotiation of governmental, organizational, and professional power relations, the notion of street-level bureaucracy illuminates the political nature of practice as well as the possibilities and boundaries that policy can place on ideal forms and outcomes of practice. IMPLICATIONS.: Framing occupational therapists as street-level bureaucrats reinforces practitioners\u27 situatedness as political actors. Mobilizing this framing can enhance awareness of occupational therapists\u27 exercise of discretion, which can be investigated as a basis for occupation-focused and emancipatory forms of practice

Resource Seeking as Occupation: A Critical and Empirical Exploration.

Occupational therapists and occupational scientists are committed to generating and using knowledge about occupation, but Western middle-class social norms regarding particular ways of doing have limited explorations of survival occupations. This article provides empirical evidence of the ways in which resource seeking constitutes an occupational response to situations of uncertain survival. Resource seeking includes a range of activities outside formal employment that aim to meet basic needs. On the basis of findings from 2 ethnographic studies, we critique the presumption of survival in guiding occupational therapy documents and the accompanying failure to recognize occupations that seem at odds with self-sufficiency. We argue that failing to name resource seeking in occupational therapy documents risks alignment with social, political, and economic trends that foster occupational injustices. If occupational therapists truly aim to meet society\u27s occupational needs, they must ensure that professional documents and discourses reflect the experiences of all people in society

Quick returns and night work as predictors of sleep quality, fatigue, work–family balance and satisfaction with work hours

<p>Quick returns (intervals of <11 h between the end of one shift and the start of the next) are associated with short sleeps and fatigue on the subsequent shift. Recent evidence suggests that shift workers regard quick returns as being more problematic than night work. The current study explored quick returns and night work in terms of their impact on sleep, unwinding, recovery, exhaustion, satisfaction with work hours and work–family interference. Data from the 2006 cohort of Swedish nursing students within the national Longitudinal Analysis of Nursing Education (LANE) study were analysed (<i>N</i> = 1459). Respondents completed a questionnaire prior to graduation (response rate 69.2%) and 3 years after graduation (65.9%). The analyses examined associations between frequency of quick returns and night work and measures taken in year three, while adjusting for confounding factors (in year three and prior graduation). Frequency of quick returns was a significant predictor of poor sleep quality, short sleeps, unwinding, exhaustion, satisfaction with work hours and work-to-family interference, with higher frequency predicting more negative outcomes. Quick returns did not predict recovery after rest days. Frequency of night work did not predict any of the outcomes. In conclusion, quick returns were an important determinant of sleep, recovery and wellbeing, whereas night work did not show such an association.</p