Preliminary Understanding of Complexities in Swimming Performance of Common Minnow (Cyprinidae) Taxa

Understanding swimming performance of native freshwater fishes has implications for ecology, conservation, and management. In particular, this type of information has practical importance for improving the understanding of fish dispersal, occurrence, migration, and invasive potential. The objective of this study was to characterize swimming performance of 2 taxa from the comparatively understudied minnow family (Cyprinidae) and test for potential drivers as a function of total length, sex, habitat, morphology, or some combination. The study assessed Spotfin Shiner (Cyprinella spiloptera; n = 66) and Bluntnose Minnow (Pimephales notatus; n = 24) populations from an ontogenic range of male and female individuals from lentic and lotic habitats in Indiana and Ohio. Akaike information criterion (AIC) model selection identified the most parsimonious linear regression model to predict swimming performance of Spotfin Shiner and Bluntnose Minnow independently. Overall, larger Spotfin Shiners were superior swimmers compared with smaller individuals. In both species, individuals having more streamlined heads and elongated caudal regions were better swimmers. Additionally, Spotfin Shiners that were collected from lotic environments were generally better swimmers than individuals from lentic environments. Models did not recover sex-specific effects in either species—or meaningful total length, or habitat effects, in Bluntnose Minnows. Overall, this study provides evidence of a complex series of swimming performance covariates when assessing or understanding performance. This has implications for aquatic population, assemblage, and community ecology as well as management and conservation efforts

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This "jet fossil record" can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) VLT/X-shooter spectra of the jet from the Herbig Ae star HD 163296. We determine physical conditions in the knots, as well as their kinematic "launch epochs". Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable in both lobes. However, the mass loss rate, velocity, and shock conditions are asymmetric. We find Mjet/Macc ~ 0.01-0.1, consistent with magneto-centrifugal jet launching models. No evidence for dust is found in the high-velocity jet, suggesting it is launched within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are likely caused by dust lifted high above the disk plane; this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.Comment: 20 pages, 11 figures, accepted for publication in Astronomy & Astrophysic

Low‐temperature growth of high resistivity GaAs by photoassisted metalorganic chemical vapor deposition

We report the photoassisted low‐temperature (LT) metalorganic chemical vapor deposition (MOCVD) of high resistivity GaAs. The undoped as‐grown GaAs exhibits a resistivity of ∼106 Ω cm, which is the highest reported for undoped material grown in the MOCVD environment. Photoassisted growth of doped and undoped device quality GaAs has been achieved at a substrate temperature of 400 °C in a modified atmospheric pressure MOCVD reactor. By using silane as a dopant gas, the LT photoassisted doped films have high levels of doping and electron mobilities comparable to those achieved by MOCVD for growth temperatures, Tg≳600 °C

Relating jet structure to photometric variability: the Herbig Ae star HD 163296

Herbig Ae/Be stars are intermediate-mass pre-main sequence stars surrounded by circumstellar dust disks. Some are observed to produce jets, whose appearance as a sequence of shock fronts (knots) suggests a past episodic outflow variability. This “jet fossil record” can be used to reconstruct the outflow history. We present the first optical to near-infrared (NIR) spectra of the jet from the Herbig Ae star HD 163296, obtained with VLT/X-shooter. We determine the physical conditions in the knots and also their kinematic “launch epochs”. Knots are formed simultaneously on either side of the disk, with a regular interval of ~16 yr. The velocity dispersion versus jet velocity and the energy input are comparable between both lobes. However, the mass-loss rate, velocity,and shock conditions are asymmetric. We find Ṁjet/Ṁacc ~ 0.01−0.1, which is consistent with magneto-centrifugal jet launching models. No evidence of any dust is found in the high-velocity jet, suggesting a launch region within the sublimation radius (<0.5 au). The jet inclination measured from proper motions and radial velocities confirms that it is perpendicular to the disk. A tentative relation is found between the structure of the jet and the photometric variability of the central source. Episodes of NIR brightening were previously detected and attributed to a dusty disk wind. We report for the first time significant optical fadings lasting from a few days up to a year, coinciding with the NIR brightenings. These are very likely caused by dust lifted high above the disk plane, and this supports the disk wind scenario. The disk wind is launched at a larger radius than the high-velocity atomic jet, although their outflow variability may have a common origin. No significant relation between outflow and accretion variability could be established. Our findings confirm that this source undergoes periodic ejection events, which may be coupled with dust ejections above the disk plane.Astronom

Superior Inhibitory Control and Resistance to Mental Fatigue in Professional Road Cyclists

Purpose: Given the important role of the brain in regulating endurance performance, this comparative study sought to determine whether professional road cyclists have superior inhibitory control and resistance to mental fatigue compared to recreational road cyclists. Methods: After preliminary testing and familiarization, eleven professional and nine recreational road cyclists visited the lab on two occasions to complete a modified incongruent colour-word Stroop task (a cognitive task requiring inhibitory control) for 30 min (mental exertion condition), or an easy cognitive task for 10 min (control condition) in a randomized, counterbalanced cross-over order. After each cognitive task, participants completed a 20-min time trial on a cycle ergometer. During the time trial, heart rate, blood lactate concentration, and rating of perceived exertion (RPE) were recorded. Results: The professional cyclists completed more correct responses during the Stroop task than the recreational cyclists (705±68 vs 576±74, p = 0.001). During the time trial, the recreational cyclists produced a lower mean power output in the mental exertion condition compared to the control condition (216±33 vs 226±25 W, p = 0.014). There was no difference between conditions for the professional cyclists (323±42 vs 326±35 W, p = 0.502). Heart rate, blood lactate concentration, and RPE were not significantly different between the mental exertion and control conditions in both groups. Conclusion: The professional cyclists exhibited superior performance during the Stroop task which is indicative of stronger inhibitory control than the recreational cyclists. The professional cyclists also displayed a greater resistance to the negative effects of mental fatigue as demonstrated by no significant differences in perception of effort and time trial performance between the mental exertion and control conditions. These findings suggest that inhibitory control and resistance to mental fatigue may contribute to successful road cycling performance. These psychobiological characteristics may be either genetic and/or developed through the training and lifestyle of professional road cyclists

Development of a World-Wide-Web/Multimedia-Base for an Undergraduate Circuit Theory Course

In this paper a report is given on the results of an experimental project for using the World Wide Web in connection with the teaching of an undergraduate University-level course. Descriptions and examples of the various techniques which were implementedare included. The use of Web-based software, as well as software developedspeci#cally for the course but distributed through the Web is discussed. Introduction One of the major opportunities #and challenges# currently available to educators is presented by the World Wide Web and other Internet-based resources. These resources can easily be visualized as providing a package of tools to implement new and revolutionary methods for teaching, for delivery of educational materials, and for the interactiveinvolvment of students and faculty in the learning process. They provide a mix of hardware and software innovations which can be applied to provide a wide range of new and novel educational methodology. Among these are: chat rooms which pro..

Understanding Swimming Performance Variation in Ohio Minnows (Cyprinidae)

Understanding variability in swimming performance of freshwater fishes has implications for improving descriptions of ecological niches, establishing evolutionary relationships, and providing management and conservation recommendations. Swimming performance is associated with anatomical, physiological, and environmental variation, although the vast majority of swimming performance research to date has focused on larger game species to the exclusion of smaller non-game taxa, which represent the largest portion of North American freshwater fish diversity. Thus, the objective of this study was to assess a previously unstudied area regarding how swimming covaries with body size, sex, watershed, and habitat types of these smaller non-game taxa. A Blazka style swimming performance chamber following a stepwise critical swimming performance (Ucrit) protocol was used to quantify individual variation in four species of common Ohio Minnows (Cyprinidae: Bluntnose Minnow, Spotfin Shiner, Sand Shiner, and Redfin Shiner). Using a series of general linear models at both a global (taxa combined) and local (taxa specific) scale trends were identified across all individuals (N=150 total individuals). First, species differed in swimming performance, even after controlling for cofactors such as body size. Second, slopes depicting relationships between swimming performance and body size were not consistent among taxa and moreover, sex did not appear to play a role in swimming ability. Lastly, species specific models indicated inconsistent differences among taxa related to watershed and habitat variation. Overall, these results provide an important contribution to furthering our understanding of small bodied non-game fishes

Understanding Swimming Performance Variation in Ohio Minnows (Cyprinidae)

Understanding variability in swimming performance of freshwater fishes has implications for improving descriptions of ecological niches, establishing evolutionary relationships, and providing management and conservation recommendations. Swimming performance is associated with anatomical, physiological, and environmental variation, although the vast majority of swimming performance research to date has focused on larger game species to the exclusion of smaller non-game taxa, which represent the largest portion of North American freshwater fish diversity. Thus, the objective of this study was to assess a previously unstudied area regarding how swimming covaries with body size, sex, watershed, and habitat types of these smaller non-game taxa. A Blazka style swimming performance chamber following a stepwise critical swimming performance (Ucrit) protocol was used to quantify individual variation in four species of common Ohio Minnows (Cyprinidae: Bluntnose Minnow, Spotfin Shiner, Sand Shiner, and Redfin Shiner). Using a series of general linear models at both a global (taxa combined) and local (taxa specific) scale trends were identified across all individuals (N=150 total individuals). First, species differed in swimming performance, even after controlling for cofactors such as body size. Second, slopes depicting relationships between swimming performance and body size were not consistent among taxa and moreover, sex did not appear to play a role in swimming ability. Lastly, species specific models indicated inconsistent differences among taxa related to watershed and habitat variation. Overall, these results provide an important contribution to furthering our understanding of small bodied non-game fishes

Understanding Swimming Performance Variation in Ohio Minnows(Cyprinidae)

Understanding variability in swimming performanceof freshwater fishes has implications for improvingdescriptions of ecological niches, establishing evolutionaryrelationships, and providing management and conservationrecommendations. Swimming performance is associatedwith anatomical, physiological, and environmentalvariation, although the vast majority of swimmingperformance research to date has focused on largergame species to the exclusion of smaller non-game taxa,which represent the largest portion of North Americanfreshwater fish diversity. Thus, the objective of this studywas to assess a previously unstudied area regarding howswimming covaries with body size, sex, watershed, andhabitat types of these smaller non-game taxa. A Blazkastyle swimming performance chamber following a stepwisecritical swimming performance (Ucrit) protocol was usedto quantify individual variation in four species of commonOhio Minnows (Cyprinidae: Bluntnose Minnow, SpotfinShiner, Sand Shiner, and Redfin Shiner). Using a seriesof general linear models at both a global (taxa combined)and local (taxa specific) scale trends were identified acrossall individuals (N=150 total individuals). First, speciesdiffered in swimming performance, even after controllingfor cofactors such as body size. Second, slopes depictingrelationships between swimming performance and bodysize were not consistent among taxa and moreover, sexdid not appear to play a role in swimming ability. Lastly,species specific models indicated inconsistent differencesamong taxa related to watershed and habitat variation.Overall, these results provide an important contributionto furthering our understanding of small bodied non-gamefishes