Respiration as a percentage of daily photosynthesis in whole plants is homeostatic at moderate, but not high, growth temperatures

• Here, we investigated the impact of temperature on the carbon economy of two Plantago species from contrasting habitats. • The lowland Plantago major and the alpine Plantago euryphylla were grown hydroponically at three constant temperatures: 13, 2

Functional regionalisation of spatial interaction data: an evalution of some suggested strategies

Three alternative approaches (the functional distance approach, the iterative proportional fitting based procedure and the intramax procedure) to the functional regionalisation of spatial interaction data are compared and evaluated in this paper. After a general discussion of the basic properties of each approach, the detailed processes that are involved in each case are illustrated by reference to a worked example. The last section of the paper presents the findings obtained by each of these approaches as a result of empirical studies of Greater London, Merseyside, and the Netherlands. The study as a whole identifies a number of ambiguities in the existing literature which point to the need for a more rigorous examination of current methodology. They also suggest that more attention needs to be given to the role that is played by aggregation procedures as against data transformation procedures in the evaluation process. Although each user must decide which of the three methods best suits his particular purposes, the results obtained by means of the intramax procedure seem generally more readily interpretable than those obtained by either of the other two methods.

Growth temperature influences the underlying components of relative growth rate: an investigation using inherently fast- and slow-growing plant species

We examined the effect of growth temperature on the underlying components of growth in a range of inherently fast- and slow-growing plant species. Plants were grown hydroponically at constant 18, 23 and 28 °C. Growth analysis was conducted on 16 contrasting plant species, with whole plant gas exchange being performed on six of the 16 species. Inter-specific variations in specific leaf area (SLA) were important in determining variations in relative growth rate (RGR) amongst the species at 23 and 28 °C but were not related to variations in RGR at 18 °C. When grown at 18 °C, net assimilation rate (NAR) became more important than SLA for explaining variations in RGR. Variations in whole shoot photosynthesis and carbon concentration could not explain the importance of NAR in determining RGR at the lower temperatures. Rather, variations in the degree to which whole plant respiration per unit leaf area acclimated to the different growth temperatures were responsible. Plants grown at 28 °C used a greater proportion of their daily fixed carbon in respiration than did the 18 and 23 °C-grown plants. It is concluded that the relative importance of the underlying components of growth are influenced by growth temperature, and the degree of acclimation of respiration is of central importance to the greater role played by NAR in determining variations in RGR at declining growth temperatures

Placement and sizing of solar PV and Wind systems in trolleybus grids

Reducing the environmental impact of transportation requires the successful integration of renewable energy sources into the electrical transportation networks. However, the mismatch between renewable generation and the intermittent bus schedules causes temporary absence of loads and creates considerable excess energy, potentially rendering the systems economically infeasible. So far, studies on integration of renewables in transport grids were limited to decentralized solar PV systems (placed at the substation level), using statistical or simplified models, and concerned mainly with increasing the trolleygrid capacity. In this paper, both PV and Wind systems are considered and studied as to maximize their direct utilization by using verified simulation models for six different sizing and placement scenarios. The Dutch trolleygrid of Arnhem is used as a case study. Scenarios I to V looked at a decentralized renewable sources placement and ultimately concluded that PV systems at low-traffic substations are best sized for complete energy-neutrality, with daily storage systems. On the other hand, those at high-traffic substations should be without storage and sized below their energy-neutrality point — ideally, using the Marginal Utilization approach (scenario III). Finally, the Centralized (Aggregated) Energy-Neutral Wind and PV Approach of scenario VI offers the best outcome, with a hybrid solution of 53% PV and 47% Wind. This scenario offers a 54.1% direct bus load coverage. In comparison, scenario I, which had attempted a grid energy-neutrality in a decentralized manner, had only achieved 32.4% direct load coverage. The outcome of scenario VI can even be pushed to values above 80% by installing storage systems.DC systems, Energy conversion & Storag

The effects of cow introductions on milk production and behaviour of the herd measured with sensors

This research paper addresses the hypothesis that cow introductions in dairy herds affect milk production and behaviour of animals already in the herd. In dairy farms, cows are commonly regrouped or moved. Negative effects of regroupings on the introduced animals are reported in other studies. However, little is known about the effects on lactating cows in the herd. In this research a herd of 53 lactating dairy cows was divided into two groups in a cross-over design study. 25 cows were selected as focal cows for which continuous sensor data were collected. The treatment period consisted of replacing non-focal cows three times a week. Many potentially influencing factors were taken into account in the analysis. Replacement of cows in the treatment period indeed affected the focal animals. During the treatment period these cows showed increased walking and reduced rumination activity and produced less milk compared to the control period. Milk production per milking decreased in the treatment period up to 0.4 kg per milking on certain weekdays. Lying and standing behaviour were similar between the control and the treatment period. The current study suggests that cow introductions affect welfare and milk production of the cows already in the herd

Pressure measurement in the reticulum to detect different behaviors of healthy cows

The aim of the current study was to investigate the relation between reticulorumen contractions and monitored cow behaviors. A purpose-built pressure measuring device was used and shown to be capable of detecting the known contraction patterns in the reticulorumen of four rumen-fistulated cows. Reticular pressure data was used to build a random forest algorithm, a learning algorithm based on a combination of decision trees, to detect rumination and other cow behaviors. In addition, we developed a peak-detection algorithm for rumination based on visual inspection of patterns in reticular pressure. Cow behaviors, differentiated in ruminating, eating, drinking, sleeping and 'other', as scored from video observation, were used to develop and test the algorithms. The results demonstrated that rumination of a cow can be detected by measuring pressure differences in the reticulum using either the random forest algorithm or the peak-detection algorithm. The random forest algorithm showed very robust performances for detecting rumination with an accuracy of 0.98, a sensitivity of 0.95 and a specificity of 0.99. The peak-detection algorithm could detect rumination robustly, with an accuracy of 0.92, a sensitivity of 0.97 and a specificity of 0.90. In addition, we provide proof of principle that a random forest algorithm can also detect eating, drinking and sleeping behavior from the same data with performances above 0.90 for all measures. The measurement device used in this study needed rumen-fistulated cows, but the results indicate that behavior detection using algorithms based on only measurements in the reticulum is feasible. This is promising as it may allow future wireless sensor techniques in the reticulum to continuously monitor a range of important behaviors of cows