A New Type of Complexometric Titration

Author Institution: Department of Chemistry, The Ohio State University, Columbus 1

Life-history consequences of divergent selection on egg size in Drosophila melanogaster

Life histories are generally assumed to evolve via antagonistic pleiotropy (negative genetic correlations) among traits, and trade-offs between life-history traits are typically studied using either phenotypic manipulations or selection experiments. We investigated the trade-off between egg size and fecundity in Drosophila melanogaster by examining both the phenotypic and genetic relationships between these traits after artificial selection for large and small eggs, relative to female body size. Egg size responded strongly to selection in both directions, increasing in the large-egg selected lines and decreasing in the small-egg selected lines. Phenotypic correlations between egg size and fecundity in the large-egg selected lines were negative, but no relationship between these traits occurred in either the control or small-egg selected lines. There was no negative genetic correlation between egg size and fecundity. Total reproductive allocation decreased in the small-egg selected lines but did not increase in the large-egg lines. Our results have three implications. First, our selection procedure may have forced females selected for large eggs into a physiological trade-off not reflected in a negative genetic correlation between these traits. Second, the lack of a negative genetic correlation between egg size and number suggests that the phenotypic trade-off frequently observed between egg size and number in other organisms may not evolve over the short term via a direct genetic trade-off whereby increases in egg size are automatically accompanied by decreased fecundity. Finally, total reproductive allocation may not evolve independently of egg size as commonly assumed

Meta-population structure in a coral reef fish demonstrated by genetic data on patterns of migration, extinction and re-colonisation

Background: Management strategies for coral reefs are dependant on information about the spatial population structure and connectivity of reef organisms. Genetic tools can reveal important information about population structure, however, this information is lacking for many reef species. We used a mitochondrial molecular marker to examine the population genetic structure and the potential for meta-population dynamics in a direct developing coral reef fish using 283 individuals from 15 reefs on the Great Barrier Reef, Australia. We employed a hierarchical sampling design to test genetic models of population structure at multiple geographical scales including among regions, among shelf position and reefs within regions. Predictions from island, isolation-by-distance and meta-population models, including the potential for asymmetric migration, local extinction and patterns of re-colonisation were examined.\ud \ud Results: Acanthochromis polyacanthus displayed strong genetic structure among regions (ΦST = 0.81, P < 0.0001) that supported an equilibrium isolation-by-distance model (r = 0.77, P = 0.001). Significant structuring across the continental shelf was only evident in the northern region (ΦST = 0.31, P < 0.001) and no evidence of isolation-by-distance was found within any region. Pairwise ΦST values indicated overall strong but variable genetic structure (mean ΦST among reefs within regions = 0.28, 0.38, 0.41), and asymmetric migration rates among reefs with low genetic structure. Genetic differentiation among younger reefs was greater than among older reefs supporting a meta-population propagule-pool colonisation model. Variation in genetic diversities, demographic expansion and population growth estimates indicated more frequent genetic bottlenecks/founder effects and subsequent population expansion in the central and southern regions compared to the northern one.\ud \ud Conclusion: Our findings provide genetic evidence for meta-population dynamics in a direct developing coral reef fish and we reject the equilibrium island and isolation-by distance models at local spatial scales. Instead, strong non-equilibrium genetic structure appears to be generated by genetic bottlenecks/founder effects associated with population reductions/extinctions and asymmetric migration/(re)-colonisation of such populations. These meta-population dynamics varied across the geographical range examined with edge populations exhibiting lower genetic diversities and higher rates of population expansion than more central populations. Therefore, coral reef species may experience local population reductions/extinctions that promote overall meta-population genetic differentiation

Plasticity of Noddy Parents and Offspring to Sea-Surface Temperature Anomalies

Behavioral and/or developmental plasticity is crucial for resisting the impacts of environmental stressors. We investigated the plasticity of adult foraging behavior and chick development in an offshore foraging seabird, the black noddy (Anous minutus), during two breeding seasons. The first season had anomalously high sea-surface temperatures and ‘low’ prey availability, while the second was a season of below average sea-surface temperatures and ‘normal’ food availability. During the second season, supplementary feeding of chicks was used to manipulate offspring nutritional status in order to mimic conditions of high prey availability. When sea-surface temperatures were hotter than average, provisioning rates were significantly and negatively impacted at the day-to-day scale. Adults fed chicks during this low-food season smaller meals but at the same rate as chicks in the unfed treatment the following season. Supplementary feeding of chicks during the second season also resulted in delivery of smaller meals by adults, but did not influence feeding rate. Chick begging and parental responses to cessation of food supplementation suggested smaller meals fed to artificially supplemented chicks resulted from a decrease in chick demands associated with satiation, rather than adult behavioral responses to chick condition. During periods of low prey abundance, chicks maintained structural growth while sacrificing body condition and were unable to take advantage of periods of high prey abundance by increasing growth rates. These results suggest that this species expresses limited plasticity in provisioning behavior and offspring development. Consequently, responses to future changes in sea-surface temperature and other environmental variation may be limited

The Effect of Motive and Coworker Liking on the Intention to Perform Organizational Citizenship Behavior

Organizational Citizenship Behavior (OCB) is defined as employee behavior that benefits others yet is not required by the employee’s job description. OCB can be divided into two categories: behavior that is either directed toward individuals (OCBI) or behavior that is directed toward the organization (OCBO). Researchers have posited that there are three different motives behind OCB: impression management, prosocial values, and organizational concern. Additionally, researchers have recognized the importance of coworker relationships within organizations and have suggested that the degree to which one likes his or her coworkers may serve as an additional source of motivation to engage in different types of OCB. This research consisted of two studies investigating the effect of motive and coworker liking on intention to engage in OCBO and OCBI. Participants in both studies read a vignette manipulating motive and degree of coworker liking. The second study incorporated two additional items in the manipulation check to increase the saliency of the coworker liking manipulation. In both Study 1 and Study 2 participants were more likely to engage in OCBO than in OCBI. Both studies failed to support the hypotheses that either motive or degree of liking would predict the type of OCB performed

Examining the Base Rates of Atrial Fibrillation in Eastern North Carolina: Community Screening, Associated Risk Factors, and Psychological Correlates of Disease

Background: Eastern North Carolina has historically high prevalence rates of cardiovascular disease. Novel solutions such as mobile screening technology may aid in reaching this region’s vulnerable health population to prevent further disease progression. Additionally, symptoms of psychological distress are commonly comorbid with cardiovascular disease but often overlooked as formal predictors or modifiers of increased disease burden. Behavioral medicine providers recognize the importance of screening for psychological stress as it relates to cardiovascular disease as a way to reduce disease burden and advancement. Therefore, mobile-ECG screening for atrial fibrillation and exploration of adding psychological variables to a well-established cardiovascular stroke risk calculator (CHA₂DS₂-VASc) are discussed. Methods: Participants (N = 250) were approached at pharmacies in Eastern North Carolina. Participants completed demographic and medical history questionnaires, the DASS-21, and were administered a single-lead mobile-ECG (mECG). All mECG readings were interpreted by the mECG device in addition to adjudication by three electrophysiologists. Medical referrals were provided when indicated. Chi-squared statistics were utilized to investigate regional rates of atrial fibrillation and associated risk factors. Binary logistic regression modeling measured the capability of the CHA₂DS₂-VASc stroke risk calculator to predict abnormal mECG readings both with and without the addition of DASS-21 symptom scores. Results: Rates of previously undiagnosed atrial fibrillation were much higher than rates found in studies of similar scope and design. Participants’ average CHA₂DS₂-VASc scores (2.68 ± 1.35) signify an alarming rate of untreated ischemic stroke risk in a community sample. Additionally, the prevalence rates of six, known independent stroke risk factors were also significantly higher in the study sample than reported national US averages. Significant correlations were not found between psychological endpoints and abnormal mECG readings or elevated CHA₂DS₂-VASc scores, but binary logistic regression modeling revealed that a longstanding stroke risk calculator could be potentially strengthened with the addition of one (anxiety) or three (depression, anxiety, and stress) psychological endpoints. Discussion: The results of the current study further the knowledge of the utility of using mobile-health techniques to capture previously undiagnosed atrial fibrillation and associated risk factors. Prevalence of chronic disease and other health metrics in the Eastern North Carolina region are substantially worse than the general US population. Additionally, the results presented begin a compelling argument for the addition of psychological symptom scores to a long-standing stroke risk calculator

Behaviour of traffic on a link with traffic light boundaries

This paper considers a single link with traffic light boundary conditions at both ends, and investigates the traffic evolution over time with various signal and system configurations. A hydrodynamic model and a modified stochastic domain wall theory are proposed to describe the local density variation. The Nagel-Schreckenberg model (NaSch), an agent based stochastic model, is used as a benchmark. The hydrodynamic model provides good approximations over short time scales. The domain wall model is found to reproduce the time evolution of local densities, in good agreement with the NaSch simulations for both short and long time scales. A systematic investigation of the impact of network parameters, including system sizes, cycle lengths, phase splits and signal offsets, on traffic flows suggests that the stationary flow is dominated by the boundary with the smaller split. Nevertheless, the signal offset plays an important role in determining the flow. Analytical expressions of the flow in relation to those parameters are obtained for the deterministic domain wall model and match the deterministic NaSch simulations. The analytic results agree qualitatively with the general stochastic models. When the cycle is sufficiently short, the stationary state is governed by effective inflow and outflow rates, and the density profile is approximately linear and independent of time

CFD Simulation of Low Reynolds-number Turbulence Models in Coral Thermal Microenvironment

The increasing frequency and severity of mass bleaching events in the past few decades has raised considerable concerns. Here we report on the numerical simulations of Low Reynolds turbulence models coral microenvironments to determine surface temperature rise in reef corals and test whether our model is capable to estimate of the extent of warming likely to be en-countered in the nature during calm conditions. The Computational Fluid Dynamics (CFD) simulation uses the OpenFOAM CFD libraries to implement a steady-state turbulent flow porous medium model, with heat transfer accounted for using a transport equation for temperature. We validated the model using controlled laboratory experiment observations