Responses of salmonids to habitat changes

Streams in western North America provide spawning and rearing habitats for several species of salmon and trout that are of substantial economic importance in the region. Timber that grows on lands through which these streams flow is also economically important, and its harvest can substantially change habitat conditions and aquatic production in salmonid streams. Undisturbed forests, the streams that flow through them, and the salmonid communities in these streams have intrinsic scientific, genetic, and cultural values in addition to their economic importance. The complex relations between salmonids and their physical environment, and the changes in these relations brought about by timber harvest, have been investigated extensively (see the bibliography by Macdonald et al. 1988). However, in spite of considerable evidence of profound changes in channel morphology and in light, temperature, and flow regimes associated with timber harvests, much uncertainty exists about the responses of salmonids to these changes

Investigating the effect of scale and scheduling strategies on the productivity of 3D managed print services

Sales of extrusion 3D printers have seen a rapid growth and the market value is expected to triple over the next decade. This rapid growth can be attributed to a step change in capability and an increase in demand for 3D printed parts within mechanical, industrial and civil engineering processes. Correspondingly, a new technical prototyping platform – commonly referred to as Fabrication Laboratories – has emerged to provide a stimulus for local education, entrepreneurship, innovation and invention through the provision of on-demand 3D printing and prototyping services. Central to the effectiveness of the on-demand 3D printing and prototyping services – hereby referred to as 3D managed print services – is their ability to handle multiple users with varying knowledge and understanding of the manufacturing processes and scaling numbers of 3D printers in order to maximise productivity of the service. It is this challenge of productivity and more specifically the scalability and scheduling of prints that is considered in this article. The effect of scale and scheduling strategies on productivity is investigated through the modelling of four scheduling strategies for 3D managed print service of varying scales by altering the number of available printers and level of user demand. The two most common approaches (first-come first-serve and on-line continuous queue) and two alternatives based on bed space optimisation (first-fit decreasing height and first-fit decreasing height with a genetic algorithm) have been considered. Through Monte-Carlo simulation and comparison of the strategies, it is shown that increasing the scale of 3D managed print service improves the peak productivity and range of user demands at which the 3D managed print service remain productive. In addition, the alternative strategies are able to double the peak productivity of 3D managed print service as well as increase the user demand range where the 3D managed print service remains productive.</p

Role of the left aortic arch and blood flows in embryonic American alligator (Alligator mississippiensis)

All embryonic and fetal amniotes possess a ductus(i) arteriosus(i) that allows blood to bypass the pulmonary circulation and the non-functional lungs. The central hemodynamic of embryonic reptiles are unique, given the additional systemic aorta that allows pulmonary circulatory bypass, the left aorta (LAo). The LAo exits in the right ventricle or ‘pulmonary side’ of reptilian hearts in both embryos and adults, but its functional significance in ovo is unknown. This study investigated the role of the LAo in embryonic American alligators by surgically occluding the LAo and measuring oxygen consumption and, in addition, measured hemodynamic responses to hypoxia in embryonic alligators. We measured systemic cardiac output and primary chorioallantoic membrane (CAM) artery blood flow for normoxic and hypoxic-incubated (10% O2) American alligator embryos (Alligator mississippiensis). Chronic blood flow (1–124 h) in the primary CAM artery for hypoxic-incubated embryos (92 ± 26 ml min−1 kg−1) was elevated when compared with normoxic-incubated embryos (29 ± 14 ml min−1 kg−1, N = 6; P = 0.039). For hypoxic-incubated embryos, acute LAo blood flow (49.6 ± 24.4 ml min−1 kg−1) was equivalent to the combined flow of the three systemic great vessels that arise from the left ventricle, the right aorta, common carotid and subclavian arteries (43.6 ± 21.5 ml min−1 kg−1, N = 5). Similarly, for normoxic-incubated embryos, LAo blood flow (27.3 ± 6.6 ml min−1 kg−1) did not statistically differ from the other three vessels (18.4 ± 4.9 ml min−1 kg−1, N = 5). This study contains the first direct test of LAo function and the first measurements of blood flow in an embryonic reptile. These data support the hypotheses that embryonic alligators utilize the LAo to divert a significant amount of right ventricular blood into the systemic circulation, and that CAM blood flow increases following chronic hypoxic conditions. However, surgical occlusion of the LAo did not affect egg \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$$\dot{V}_{{\text{O}}_{2}},$$\end{document} supporting the hypothesis that the LAo of reptiles is not critical to maintain in ovo oxygen consumption

The emergent structures in digital engineering work:what can we learn from dynamic DSMs of near-identical systems design projects?

Design structure matrices (DSMs) are widely known for their ability to support engineers in the management of dependencies across product and organisational architectures. Recent work in the field has exploited product lifecycle management systems to generate DSMs via the co-occurrence of edits to engineering files. These are referred to as dynamic DSMs and results have demonstrated both the efficacy and accuracy of dynamic DSMs in representing engineering work and emergent product architectures. The wide-ranging applicability of the theoretical model and associated analytical process to generate dynamic DSMs enables investigations into the evolving structures within digital engineering work. This paper uses this new capability and presents the results of the world's first comparison of dynamic DSMs from a set of near-identical systems design projects. Through comparison of the dynamic DSMs' end-of-project state, change propagation characteristics and evolutionary behaviour, 10 emergent structures are elicited. These emergent structures are considered in the context of team performance and design intent in order to explain and code the identified structures. The significance of these structures for the management of future systems design projects in terms of productivity and efficacy is also described.</p

Meeting the requirements for supporting engineering design communication – Partbook

The Engineering Design Environment is evolving in many ways. Considerable amounts of data, information and knowledge are 'building up' within engineering companies and engineers are becoming involved in ever-more distributed collaboration activities to tackle complex multi-disciplinary challenges in the design of new products requiring the need to share knowledge. These changes are placing further challenges on Engineering Design Communication (EDC, a fundamental knowledge sharing activity) as the current methods of communication were never specifically designed to support such technical and highly-contextual communication. Much research has been performed on understanding EDC, thus enabling a list of requirements to support EDC to be generated. Therefore, this paper proposes a prescriptive tool, (PartBook) which instantiates these requirements and looks at the next steps being taken to evaluate the tool in meeting the requirements

The Relationship between Upper Arm Anthropometrical Measures and Vertical Jump Displacement

The purpose of this study was to determine if upper body segment length or mass contributes to vertical jump (VJ) displacement. Seventeen men (n=9) and women (n=8) who were active recreationally participated in this investigation. Subjects performed VJ for maximal displacement, and skeletal length measurements of the humerus (acromion following the lateral lip to the greater tuberosity), ulna (olecranon to the ulnar styloid process), and hand (lunate to distal end of third phalanx) were obtained by palpation of boney landmarks and a standard tape measure. Pearson Product Moment Correlation Coefficients were used to compare the data with statistical significance accepted at the p=0.05 level. Length of the ulna was the only upper body limb measurement that was significantly correlated with the vertical jump (P = 0.04). As the regression equation to predict VJ from ulnar length was not significant, it appears that neither intrinsic upper arm skeletal length nor arm segment mass is a strong predictor of VJ displacement