Dynamic properties of crushed concrete used in pavement structures

To reduce the environmental impact of transport in expanding cities, mass transport is an effective solution but it needs large amounts of good-quality aggregate. Recycled crushed concrete from demolition sites has the potential of substituting some of the conventionally used materials in railway construction due to its high strength and stiffness. However, knowledge about the dynamic properties of crushed concrete is very limited both in Finland and internationally. This limits the possibilities of assessing the groundborne vibrations, and hence there is a risk that the vibration levels become too large. Given the need for sustainable solutions and the large potential of crushed concrete, the dynamic properties of crushed concrete are studied and compared with conventionally used materials through a finite element simulation. In this thesis, an extensive literature review is conducted on railway dynamics and dynamic and small-strain properties of materials. The railway dynamics are studied through empirical models and conventional engineering dynamics. Based on the information found from the literature review, the small- strain stiffness affects significantly both damping, resonance frequency, and displacements related to the dynamic loading from railways. However, the existing empirical models are simplified to an extend where these properties are not included. Existing methods for estimating the small-strain stiffness and dynamic properties are also studied in the literature review, where the properties are estimated by several different methods. A resulting outcome of the literature review is an estimation of the behaviour of crushed concrete exposed to dynamic loading, where a small-strain shear modulus is found using a method by (He, et al., 2018) to be around 350 MPa at pressure of 400 kPa. The crushed concrete is tested by resonant column and bender element test to determine the small-strain properties of the material. The small-strain stiffness found from laboratory tests is 656 MPa at 300 kPa, which is around 30% larger than the estimated value. However, by analysing the measured values with the estimated values, a correction of the assumed void ratio and particle density yield a good fit. The conventionally used materials and the crushed concrete is compared through finite element simulations. The compari- son shows no significant difference in the vibration dispersion and propagation resulting from the different materials. The velocities transmitted to the surrounding material are damped nearly equally fast for the compared materials. There is a small difference to the stronger ballast material and similar results between the subgrade and crushed concrete. The surrounding material seem to have a strong effect on the vibration propagation, which calls for an extended study on the geometry’s influence on the wave propagation

Measuring degradation of transgenic DNA and screening for horizontal gene transfer from GMO-plant material during composting

The experiments show that composting of GM plant residues greatly increases the rate of degradation of transgenic DNA compared to the rate for plant residues left in the soil. If the persistence of transgenic DNA in the environments is considered as the only risk factor, composting is a 'DNA-safe' method to treat GM plant residues. However, even though transgenic plant DNA was not detected in bacterial isolates in our experiments, we cannot conclude that horizontal gene transfer can not take place. The 300 isolates tested proved to be too low a number to be conclusive. The numbers of isolates tested were based on the screenings indicating high transfer, but the screenings were biased apparently because some Bacillus species gave PCR products matching the transgenic DNA. Thus, it is still an open question if composting constitutes a safe way of disposing of GM plant residues. Furthermore, these experiments give rise to other interesting questions, e.g., the behavior of GM plant materials decomposing in waste piles or manure yards under composting-like conditions and the possibility of horizontal gene transfer to indigenous bacteria at the comparably lower temperatures presentat these environments.These questions need to be assessed if the risk associated with the use of GM plants is to be thoroughly investigated

Laser scaring of geese : a useful tool for farmers?

Gåsebestandene i Europa har vokst kraftig de siste 50 årene, og konfliktnivået mellom gjess og landbruk har vokst i takt med bestandene. Etterspørselen etter skade- og konfliktdempende tiltak er betydelig. Sterkt lys har vist seg å ha god skremmeeffekt på fugl, og laser som skremmemiddel har blitt brukt siden 1970-tallet. Laserens effekt har i noen grad blitt nærmere undersøkt, men lite er gjort for å dokumentere hvilke faktorer som påvirker effekten. Det er dette som har blitt sett nærmere på i dette studiet, mer spesifikt hva som påvirker sannsynligheten for at gjessene blir skremt, hvor lang tid det tar å skremme dem og hvor lang tid før de kommer tilbake. I tillegg er det undersøkt om det er noen forskjeller mellom de ulike artene i responsen til laser. Forsøkene ble gjort i Torsnes i Fredrikstad kommune i juni 2021, et område med store utfordringer knyttet til landbruksskader forårsaket av gjess. Grågås (Anser anser), hvitkinngås (Branta leucopsis) og kanadagås (B. canadensis) er artene som laseren ble utprøvd på. Ved hjelp av en håndholdt laser ble gjess skremt fra et bestemt jorde, og tiden det tok å skremme hele flokken ble målt. I tillegg ble en rekke variabler registrert. I 84% av forsøkene lyktes det å skremme gjessene, og det tok i gjennomsnitt 24 sekunder. Flokkstørrelse påvirket skremmesannsynligheten mest, og flere gjess gir større sannsynlighet for vellykket skremming. Ingen av artene påvirket denne sannsynligheten nevneverdig. 60% av flokkene lot seg skremme innen 20 sekunder, og denne tiden ble påvirket av flokkstørrelse og skydekke. Større flokker ga lengre skremmetider. Overskyet vær gir kortere skremmetider, og forklares ved at laserstrålen er lettere å se når det er overskyet enn i solskinn, som stemmer overens med tidligere studier. Høyere andel kanadagås i flokken ga lengre skremmetider, men dette antas å skyldes at det i forsøk med mye kanadagås også var nokså store flokker. Av faktorer som påvirker returtiden er det andelen grågås i flokkene og skydekke som har en innvirkning på dette, og jo høyere andel grågås i flokken jo fortere kommer gjessene tilbake. Gjessene kom også raskere tilbake i overskyet vær, men siden man ikke kan si med sikkerhet at det var de samme gjessene som kom tilbake er disse resultatene noe usikre. At flokkstørrelse påvirker skremmesannsynligheten skyldes trolig at det i en større flokk er større sannsynlighet for at trusler oppdages. Laseren viste seg å være et effektivt hjelpemiddel for å skremme gjess, i alle fall på kort sikt. Videre studier bør undersøke langtidseffektene på ikke-hekkende gjess da de er mer mobile enn hekkefugler, samt sammenligne effektene av skadefelling og laserskremming for å vurdere hvilken metode som er mest effektiv.The European goose populations have increased significantly over the past 50 years, and the level of conflict with agriculture has grown correspondingly. The demand for action to reduce the damage and conflicts are high. Bright light has been shown to have a good scaring effect and lasers have been used since the 1970's. The effect of lasers has in some degree been subject to science, but there is little knowledge about the factors affecting its effect. These factors are the subject of this thesis, more specifically factors affecting the probability of the geese being scared, the time needed to scare them and the time before they return after scaring. Possible differences between species were also analysed. The study was conducted in Fredrikstad municipality, Viken county in June 2021, an area with significant challenges related to geese and damage to crops. Laser trials were conducted on Greylag goose (Anser anser), Barnacle goose (Branta leucopsis) and Canada goose (B. canadensis). Geese were scared from the field using a hand held laser, and the time needed to displace them from the trial field was measured, as well as several environmental factors. Successful scaring was achieved in 84% of the trials, with an average scaring time of 24 seconds. Flock size affected scaring probability the most, and the probability increased with the number of geese. There were no significant differences in response between the different goose species. 60% of the flocks were displaced in less than 20 seconds, and this was correlated with flock size and cloud cover. Bigger flocks resulted in longer displacement times. A clouded sky resulted in less time needed to displace the Geese, and this is probably due to the laser beam being more visible under cloudy conditions, which is consistent with earlier studies. A higher proportion of Canada goose in the flock gave longer displacement time, but this is presumably due to flocks with a high proportion of Canada goose also having a higher total number of geese. The geese returned quicker when the flocks had a large proportion of Greylag goose and when the sky was cloudy, although it is uncertain whether these are the same individuals. The correlation between flock size and probability of successful scaring is probably due to the increased awareness in bigger flocks, as more eyes have a higher chance of detecting dangers. The laser proved to be an efficient tool for scaring geese, at least in a short term. Further studies should focus on the effects on non-breeding geese as these are less bound to a location than breeding birds, as well as comparing effects of derogation shooting and laser scaring in order to compare the efficiency of the two methods.M-N

Had, humor og bystander-reaktioner: danske unges reaktioner på politisk hadefulde memes

En udfordring med hadefuldt indhold på sociale medier er, at det ofte er pakket ind i en tilsyneladende uskyldig humor. Det gør det hadefulde materiale sværere at genkende og afkode. De fleste kan genkende hadefuld propaganda, når det følges af et hagekors eller et IS-flag. Men hvordan ser det ud, når det hadefulde budskab er præsenteret som et humoristisk meme? Samtidig rejser eksponering for hadefuldt materiale på sociale medier et vigtigt spørgsmål om, hvordan vi som bystanders reagerer. Hvornår intervenerer bystanders prosocialt og for eksempel anmelder hadefuldt indhold, og hvornår reagerer de antisocialt og deler og liker sådant indhold? Artiklen bidrager med en første kortlægning af danske unges vurdering af hadefulde memes, og hvordan disse vurderinger medformer de unges bystander-reaktioner i forhold til deres villighed til at like, dele og anmelde indholdet. Desuden undersøges det, hvad der kendetegner dem, som er tilbøjelige til at reagere henholdsvis prosocialt og antisocialt på hadefulde budskaber på sociale medier med hensyn til køn, politisk interesse samt aktivistiske og politisk voldelige intentioner. Artiklen trækker på en elektronisk spørgeskemaundersøgelse blandt 814 danske folkeskole- og gymnasieelever i alderen 13 til 18 år