Evaluating the impact of transmission mode, calibration level and farmer compliance in simulation models of paratuberculosis in dairy herds

AbstractSimulation models can predict the outcome of different strategies for the control and eradication of paratuberculosis (PTB) in dairy herds. Two main transmission modes have previously been used to simulate the spread of PTB: direct (contact between animals) and indirect (through the environment). In addition, previous models were calibrated to either low or high within-herd prevalence levels, which we refer to as normal and low hygiene levels, respectively. We simulated both direct and indirect transmission with the same model in both normal and low hygiene level scenarios. The effectiveness of a test-and-cull strategy was dependent on the calibration level of the simulation model, and eradication occurred less frequently with the more biologically plausible indirect transmission mode. The results were compared to within-herd prevalence records from 314 dairy herds. The prevalence in 50% of the herds varied less than 0.9% per year on average, and less than 4% in 90% of the herds. We therefore conclude that the normal-hygiene scenario best describes most dairy herds in Denmark. Finally, we simulated different levels of farmer compliance with a test-and-cull strategy and found that a 60% compliance level was not sufficient to reach eradication within 10 years.</jats:p

Observations of movement dynamics of flying insects using high resolution lidar

Insects are fundamental to ecosystem functioning and biodiversity, yet the study of insect movement, dispersal and activity patterns remains a challenge. Here we present results from a novel high resolution laser-radar (lidar) system for quantifying flying insect abundance recorded during one summer night in Sweden. We compare lidar recordings with data from a light trap deployed alongside the lidar. A total of 22808 insect were recorded, and the relative temporal quantities measured matched the quantities recorded with the light trap within a radius of 5 m. Lidar records showed that small insects (wing size 2.5 mm 2 in cross-section) were most abundant near the lidar beam before 22:00 and then moved towards the light trap between 22:00 and 23:30. We could distinguish three insect clusters based on morphology and found that two contained insects predominantly recorded above the field in the evening, whereas the third was formed by insects near the forest at around 21:30. Together our results demonstrate the capability of lidar for distinguishing different types of insect during flight and quantifying their movements

Blended learning for korte og specialiserede undervisningsforløb

Artiklen beskriver etableringen og justeringen efter den første gennemførelse af et treugers-kursus på DTU i simuleringsmodeller for sygdomsspredning. Deltagerne skal både lære de nødvendige programmeringsfærdigheder til at kunne skrive si-muleringskoden, og de skal lære teori og praksis omkring simulering. Vi fokuserer her på tre udfordringer omkring dette kursus. Kurset er delt op i en off-campus-uge, hvor de studerende skal lære at programmere, og dernæst to on-campus-uger, hvor de skal lære at simulere og bruger deres programmeringsfærdigheder på en selv-valgt projektopgave. Med få justeringer blev off-campus-delen optimeret, så den understøtter on-campus-delen. De studerende fik mere fleksibilitet i arbejdstiden den første uge, og de fagligt svage studerende kunne bruge mere tid, mens kursets forløb blev varieret. Her beskrives styrker og svagheder ved gennemførelsen af kur-set som blended learning. Generelt viste blended learning sig at være en udmærket metode til at give studerende og undervisere mere fleksibilite

Daily Evolution of the Insect Biomass Spectrum in an Agricultural Landscape Accessed with Lidar

We present measurements of atmospheric insect fauna intercepted by a static lidar transect over arable and pastoral land over one day. We observe nearly a quarter million of events which are calibrated to optical cross section. Biomass spectra are derived from the size distribution and presented against space and time. We discuss detection limits and instrument biasing, and we relate the insect observations to relevant ecological landscape features and land use. Future directions and improvements of the technique are also outlined