Hydraulic design of an optimised vertical-slot fishway targeted at multi-range fish-biology based design criteria for low, medium and high river flows

The trend towards reduced operational inputs and maintenance requirements requires fishways to be increasingly self-regulating. This emphasizes the need for a robust understanding of fish migration ecology and the establishment of biology based hydraulic design criteria targeted at low, medium and high flow ranges. Consequently, the hydraulic design of technical fishways such as the vertical-slot has increased in complexity with innovations needed to achieve optimised fish passage performance for a broad range of fish species and sizes, over a wide range of river flow conditions and with minimal compromises. The challenges are amplified at a barrier site with a high maximum differential head across a fixed-crest rockfill weir, an associated large tailwater range and large variability in the upstream limit of fish movement making fishway entrance location difficult. An innovative vertical-slot fishway has been designed for a large maximum differential head of 4.4m, that comprises two fishway entrances and a single fishway exit. The objective was to optimise passage for fish in the size range of 20-700mm at river flows ranging between near zero and flood flows that cause weir drown-out. The fishway is designed to be self-operating without external operational input or the need for mechanised control gates. This contrasts with a more typical approach that may use multiple gated exits or potentially have compromised fishway entrance attraction conditions for a significant period. The work covers low and high flow fishway entrance arrangements and fishway baffles with variable slot geometry aimed at delivering hydraulic performance that meets the targeted fish passage objectives inherent in the developed multi-range design criteria. The long-term benefits for owners of an operationally simple fishway with minimized maintenance demands comes at the expense of a more challenging design process that requires a cohesive collaboration between fish biologists, experienced design engineers, asset owners and stakeholders

The Goose - Step

https://digitalcommons.library.umaine.edu/mmb-vp/4210/thumbnail.jp

Stress in native grasses under ecologically relevant heat waves

Future increases in the intensity of heat waves (high heat and low water availability) are predicted to be one of the most significant impacts on organisms. Using six native grasses from Eastern Australia, we assessed their capacity to tolerate heat waves with low water availability. We were interested in understanding differential response between native grasses of differing photosynthetic pathways in terms of physiological and some molecular parameters to ecologically relevant summer heat waves that are associated with low rainfall. We used a simulation heatwave event in controlled temperature cabinets and investigated effects of the different treatments on four stress indicators: leaf senescence, leaf water content, photosynthetic efficiency and the relative expression of two heat shock proteins, Hsp70 and smHsp17.6. Leaf senescence was significantly greater under the combined stress treatment, while declines in leaf water content and photosynthetic efficiency were much larger for C3 than C4 plants, particularly under the combined stress treatment. Species showed an increase in expression of Hsp70 associated with heat treatment, rather than drought stress. In contrast Hsp17.6 was only detected in two species, responding to heat rather than drought, although species\u27 responses were variable. Overall, the C3 species were less tolerant than C4 species. Variation in individual plants within species was evident, especially under multiple stresses, and indicates that losses of individual plants may occur during a heat wave associated with this variability in tolerance. Heat waves will impose significant stress on plant communities that would not otherwise occur when heat and drought stress are experienced singly. Using ecologically relevant heat stress is likely to yield better predictability of how native plants will cope under a hotter, drier future

Popular culture, participation and progression in the literacy classroom

In this paper, I share an account of what happens when a teacher values children's experiences of popular culture in a classroom activity. Drawing on a socio-cultural approach to learning, I suggest that children are not simply enthused when their lived cultures are valued in the classroom but more fundamentally that they are motivated because they can participate in (and are not excluded from) the learning that is constructed. Drawing on data from a recent media literacy research project, I aim to demonstrate the necessity of including popular culture experiences in literacy teaching in order to ensure that children are able to articulate and develop key conceptual understandings. Furthermore, I suggest that interrogatory pedagogic strategies, including practical productions, are key to ensuring that children are able to make explicit, and then organise and develop their conceptual understandings

Reducing dose for digital cranial radiography : The increased source to the image-receptor distance approach

This investigation proposes that an increased source to the image-receptor distance (SID) technique can be used to optimize occipital frontal and lateral cranial radiographs acquired with direct digital radiography. Although cranial radiography is not performed on a routine basis, it should nonetheless be optimized to keep the dose to the patient as low as reasonably achievable, particularly because it can form part of the facial bone and sinus series. Dose measurements were acquired at various SIDs, and image quality was assessed using visual grading analysis. Statistically significant reductions in the effective dose between 19.2% and 23.9% were obtained when the SID was increased from the standard 100 to 150 cm (P ≤.05), and visual grading analysis scores indicate that image quality remained diagnostically acceptable for both projections. This investigation concludes that increasing the SID effectively optimizes occipital frontal and lateral skull radiographs. Radiology departments must be advised of the benefits of this technique with the goal of introducing an updated reference SID of 150 cm into clinical practice.Peer reviewe