Reducing the nitrate content of protected lettuce.

End of Project ReportA research project was carried out jointly between Teagasc, Kinsealy Research Centre and University College Dublin, Department of Crop Science, Horticulture and Forestry which studied the effects of cultivar, nitrogen fertilisation and light intensity on the nitrate content of protected butterhead lettuce. In a series of cultivar trials of winter and summer butterhead lettuce, significant differences in the nitrate content of the lettuce between cultivars were found only in one experiment. In this instance, the differences were not consistent between successive harvests. It was concluded that screening lettuce cultivars for tissue nitrate level is unlikely to contribute to an overall reduction of nitrate levels. The application of N in a liquid feed throughout the cropping period resulted in higher nitrate levels in lettuce plants grown in soil filled containers compared with a similar amount of N applied to the soil before planting. Withdrawing N for the final 10 days of the cropping period did not affect the nitrate content of the lettuce. In an experiment studying nitrogen source and rate on lettuce grown in containers, the use of calcium cyanamide as a N source resulted in lower nitrate levels in the lettuce and gave a reduced head weight compared with calcium ammonium nitrate (CAN) or ammonium sulphate. Increasing the rate of CAN or ammonium sulphate gave higher lettuce nitrate levels. A nitrification inhibitor reduced the soil nitrate levels especially with sulphate of ammonia as the N source but did not affect the plant nitrate levels significantly. The addition of chloride to the soil reduced nitrate levels in the lettuce. In a further fertilisation study using containers, calcium cyanamide again resulted in lower plant nitrate levels than CAN. Increasing the rate of CAN increased soil nitrate levels, lettuce head weight and plant nitrate levels. The relationship between soil nitrate levels, lettuce head weight and plant nitrate level indicates that the level of 100-150 mg·L-1 of nitrate N in the soil, advocated in the Code of Good Practice, is a compromise between maximising plant growth and minimising lettuce nitrate content. A comparison between CAN and calcium cyanamide in a border soil experiment again showed that the latter N source resulted in lower lettuce nitrate levels. In this experiment the addition of chloride to the soil did not affect plant nitrate levels. Lettuce was grown, in late summer, in small tunnels using a range of polyethylene cladding materials. Head weight correlated well with the overall light transmission of the materials. In one of the materials that had a low light transmission, lettuce nitrate content was doubled compared with those grown under the materials with high light transmission. Under both winter and summer conditions, the nitrate content of lettuce heads was not influenced by the time of day at which harvest took place. In experiments in which multiple harvests were carried out there was no consistent trend in nitrate content as the heads developed and matured. Within individual heads of lettuce there was a steep concentration gradient with the older outer leaves having much higher concentrations of nitrate than the younger inner leaves. Herbicides commonly used in protected lettuce production did not influence the nitrate content of the lettuce

Executive Function Capacities, Negative Driving Behavior and Crashes in Young Drivers

Motor vehicle crashes remain a leading cause of injury and death in adolescents, with teen drivers three times more likely to be in a fatal crash when compared to adults. One potential contributing risk factor is the ongoing development of executive functioning with maturation of the frontal lobe through adolescence and into early adulthood. Atypical development resulting in poor or impaired executive functioning (as in Attention-Deficit/Hyperactivity Disorder) has been associated with risky driving and crash outcomes. However, executive function broadly encompasses a number of capacities and domains (e.g., working memory, inhibition, set-shifting). In this review, we examine the role of various executive function sub-processes in adolescent driver behavior and crash rates. We summarize the state of methods for measuring executive control and driving outcomes and highlight the great heterogeneity in tools with seemingly contradictory findings. Lastly, we offer some suggestions for improved methods and practical ways to compensate for the effects of poor executive function (such as in-vehicle assisted driving devices). Given the key role that executive function plays in safe driving, this review points to an urgent need for systematic research to inform development of more effective training and interventions for safe driving among adolescents

Sleep Profiles of Elite Swimmers During Different Training Phases

This study aims to describe the sleeping patterns during different training phases in competitive swimmers. Twelve national- and international-level swimmers (3 females and 9 males) were monitored during 4 different phases, consisting of a preparation training phase, a taper phase, a competition phase, and a rest phase. Sleep parameters were assessed using wrist activity monitors and self-reported sleep diaries. There was a moderately higher (d = 0.70–1.00) sleep onset latency during the competition phase compared with taper, train, and rest phases. Trivial to small differences were observed for total sleep time between phases (d = 0.05–0.40). Sleep efficiency was moderately higher (d = 0.60–0.75) in the training and taper phases compared with competition and rest. Restfulness and fragmentation index (FI) were lowest in the rest with differences between phases being small (d = 0.43–0.51) for restfulness and small to moderate (d = 0.43–0.62) for FI. Time in and out of bed was very largely later (d = 1.96–2.34) in rest compared with the other phases. Total nap time was moderately lower in rest (d = 1.13–1.18) compared with the training and competition phases, whereas there was a small difference (d = 0.46) compared with taper. To conclude, while there were trivial to small differences in sleep quantity between phases, there are small to moderate differences in other sleep parameters. Specifically, sleep onset latency was higher during the competition phase. In addition, this study highlights the substantial between-individual variations in sleep responses during different training phases

Estimating the potential yield of small building-mounted wind turbines

The wind profile in the urban boundary layer is described as following a logarithmic curve above the mean building height and an exponential curve below it. By considering the urban landscape to be an array of cubes, a method is described for calculating the surface roughness length and displacement height of this profile. Firstly, a computational fluid dynamics (CFD) model employing a k-ϵ turbulence model is used to simulate the flow around a cube. The results of this simulation are compared with wind tunnel measurements in order to validate the code. Then, the CFD model is used to simulate the wind flow around a simple pitched-roof building, using a semi-logarithmic inflow profile. An array of similar pitched-roof houses is modelled using CFD to determine the flow characteristics within an urban area. Mean wind speeds at potential turbine mounting points are studied, and optimum mounting points are identified for different prevailing wind directions. A methodology is proposed for estimating the energy yield of a building-mounted turbine from simple information such as wind atlas wind speed and building density. The energy yield of a small turbine on a hypothetical house in west London is estimated. The energy yield is shown to be very low, particularly if the turbine is mounted below rooftop height. It should be stressed that the complexity of modelling such urban environments using such a computational model has limitations and results can only be considered approximate, but nonetheless, gives an indication of expected yields within the built environment

Werewolves and warning signs: Cultural responses to tropical cyclones in Mauritius

publishedVersio

A taphonomic analysis of the vertebrate material from Allen's Cave : implications for Australian arid zone archaeology

This thesis analyses an extensive bone deposit from Allen's Cave, which is situated on the southern Nullarbor, South Australia. Excavation of the site in 1989 yielded evidence for 38,000 years of human occupation, the first 25,000 years of which took place under extremely arid conditions. A taphonomic analysis of the bone debris was undertaken in order to identify patterns of Aboriginal arid zone subsistence and occupation. The bone debris consists of skeletal material from a range of small to large prey. The smaller species are both better represented and preserved than larger species. Primary deposition by owls and carnivores and significant modification of human-deposited bone is clearly demonstrated. Previous vertebrate analyses which have aimed at identifying humandeposited bone from such mixed and. fragmented deposits were found to display on-going methodological problems. These problems were largely based on misunderstandings about the behavior of predators associated with the cave sites. Therefore a comprehensive review of the taphonomic effects of a range of carnivores in human occupation sites has been undertaken. Revision of earlier methodologies also revealed that expectations concerning the capacity of the highly fragmented and diminished amount of human discard to provide evidence of subsistence and occupation were overstated. Thus a taphonomic methodology focussing on the far greater quantity of non-cultural bone debris has been formulated for Allen's Cave. It is anticipated that this will also be applicable to similar deposits in sites elsewhere