The evaluation of an ozone purification system in a recirculating aquaculture system

An Ozone Purification System (OPS, Robert B. Hill Co., Minneapolis, MN) was evaluated to determine its potential as a reconditioning agent for the water within an intensive culture system using original cross hybrid striped bass. In the first of two 36-day trials, two stocking densities (3.5 g/L (1X)), and 7.1 g/L (2X)) in the recirculating systems were compared to a 3.5 g/L (1X) stocking rate in the typical flow through system (i.e., the water is only used once). At stocking, mean weight and length per system averaged 11.6 g / 100 mm, 12.6 g / 102 mm, and 11.2 g / 101 mm for the flow-through system and single and double density systems, respectively. Final weights ranged from 33.8 g in the flow-through system to 30.0 g in the single density system and 21.8 g in the double density system. The second trial evaluated only the recirculating systems using stocking densities of 4.8 g/L (1X) and 9.5 g/L (2X). Stocking measurements for the 1X system were 34.0 g and 135 mm and 34.0 g and 137 mm for the 2X system. Final weights were 47.5 g and 44.0 g for the 1X and 2X systems, respectively. A photoperiod was kept on a 12 hour dark/12 hour light cycle during the study. An economic analysis on the cost effectiveness of use the Ozone Purification System within the recirculating system was significantly more effective at growing fish than the flow-though system stocked at the same density

COMPARISON OF THE BILATERAL AND UNILATERAL BARBELL HIP THRUST

The purpose of this study was to quantify the kinetics and kinematics of the unilateral (UL) barbell hip thrust and compare UL biomechanics with the bilateral (BL) barbell hip thrust. Ten resistance trained males performed three sets of three repetitions UL and BL at 10 repetition maximum intensity. The biomechanics of each lift were analysed using 3D motion capture and force plates that were floor mounted and instrumented in to a bespoke rig. Joint kinetics and kinematics were calculated in the sagittal, frontal and transverse planes. It was concluded that UL loaded the hip joint to a greater extent than the BL across all three planes. The current study offers novel insight to the biomechanical demand of the unilateral hip thrust and has implications for exercise selection within the physical preparation of athletes

Horizontal force production and multi-segment foot kinematics during the acceleration phase of bend sprinting

This paper investigated horizontal force production, foot kinematics and metatarsophalangeal (MTP) joint push-off axis use during acceleration in bend (anti-clockwise) and straight-line sprinting. It was hypothesised that bend sprinting would cause the left step push-off to occur about the oblique axis, resulting in a decrease in propulsive force. Three-dimensional kinematic and ground reaction force data were collected from nine participants during sprinting on the bend (36.5 m radius) and straight. Anteroposterior force was reduced at 38-44% of stance during bend sprinting compared with the straight. This coincided with an increase in mediolateral force for the majority of the stance phase (3-96%) on the bend compared with the straight. In addition, a lower propulsive impulse was reported on the bend compared with the straight. Analysis of multi-segment foot kinematics provides insight into the possible mechanisms behind these changes in force production. Mean mediolateral centre of pressure position was more lateral in relation to the second metatarsal head in the left step on the bend compared with the straight, indicating the oblique axis was used for push-off at the MTP joint. Greater peak joint angles of the left foot were also reported, in particular, an increase in left step midfoot eversion and internal ankle rotation. It is possible these changes in joint kinematics are associated with the observed decrease in propulsive force. Therefore, practitioners should seek to strengthen muscles such as tibialis posterior in frontal and sagittal planes and ensure specificity of training which may aid in addressing these force reductions

Direct observation of yield in films by flat punch indentation

In regular indentation many strain states are simultaneously present in the indented region, so measured parameters such as hardness and modulus are average values over a wide range of strains. Testing of structures such as pillars, levers or film bulges enables determination of yield point and modulus with uniform strains in the sample, but requires specialised sample preparation and can be significantly affected by surface condition. Here we show how in-situ indentation with a flat punch allows direct observation of a discrete yield point in soft films on more rigid substrates. The yield point is clearly observable from the load displacement behaviour and from post indent AFM imaging. The film is in uniform uniaxial strain. Finite element simulations show that effective self-confinement by surrounding film material leads to uniformity throughout the film material down to surprisingly low aspect ratios around 4:1. This occurs for a significant range of stresses above the yield point. Eventually at even higher stresses the film material is extruded laterally. The characteristics of the yield event will be described as a function of temperature and film thickness for thin to ultrathin films. At higher aspect ratio and with sufficient stiffness of punch and substrate, quantitative, in-situ measurement of intrinsic stress vs. strain to well beyond the elastic limit becomes possible for thin films. The extent to which full constitutive relations for polymer films can be determied will be discussed, along with limitations of the technique

Evaluation Rainfall Regime at the Hydroelectric Power Plant Toward Climate Change

The hydroelectric plants are first in the Brazilian energy matrix, so irregularities in the rainfall regime can affect the energy generation, thus evidencing the need to know the rainfall distribution in the studied area. This work aimed to evaluate possible analysis of the impacts of climate change on the rainfall regime in the Machadinho hydroelectric region. For the research development, the IPCC-AR5 pessimistic scenario was used, representing a scenario with a continuous population growth and high carbon dioxide emissions. From the historical series and organized projections, precipitation anomalies were calculated. Analyzing the difference between the average of the month and the climatological normal, it was inferred that the model used presented a positive trend for precipitation in the period from 2026 - 2100, projecting anomalies between 25 and 200 mm per month. A greater amplitude is observed in the precipitation of 2076-2100, indicating an increase in the occurrence of extreme events of precipitation, mainly in the spring period. Considering that the rains in the Machadinho hydroelectric region are increasing in the scenarios analyzed, the average water level in the reservoir of the plant tends to increase