Eight-year exploration of shrinkage in high-performance concrete

In this paper, an experimental and analytical exploration on the effect of water-binder ratio (w/b), silica fume and age on autogenous, carbonation, drying and total shrinkage of high-performance concrete (HPC) is outlined. Eight types of HPC were studied. Carbonation, internal relative humidity (RH) and strength were studied on specimens from the same batch of HPC that was used in the studies of shrinkage. The results indicate fairly good correlation between carbonation, shrinkage, w/b and RH. The type and amount of silica fume affected shrinkage.     

Relationship between the attenuation of downwelling irradiance at 490 nm with the attenuation of PAR (400 nm-700 nm) in the Baltic Sea

The vertical attenuation coefficient of diffuse downwelling irradiance at 490 nm (K_d 490) is a parameter that we routinely derive from SeaWiFS images of the Baltic Sea. Here, through model simulations, we examine the relationship between K_d(490), and the vertical attenuation coefficient of PAR (K_d PAR), as this later coefficient determines the light available for aquatic photosynthesis. A simple semi-analytical model is used to predict K_d(490) and K_d(PAR), as a function of the concentrations of chlorophyll, colored dissolved organic material (CDOM), suspended inorganic, and suspended organic particulate material. A series of model simulations based on variations in these optically significant constituents over a range realistic for the Baltic Sea, are used to define the relationship between the two attenuation coefficients.

Kd(PAR)=0.6677Kd^0.6763(490).     

Detection and reading distances of retroreflective road signs during night driving

The detectability and legibility of road signs of different reflective intensities were studied in night driving conditions. The results indicated that for obtaining optimal detectability and legibility distances, the reflective intensity of a new road sign should be in the range of 4 to 10 mcd/lux x cm(2). For signs in this range it was shown that doubling the area of a sign increased a detection distance of about 600 m by about 150-200 m. Opposing headlights on an oncoming car decreased detection distances of 500-900 m by about 100 m. Finally, it was found that standard signs, with a text 170 mm high, permitted reading from a distance of about 115 m.     

On the internal frost resistance of self-compacting concrete, with and without polypropylene fibres

In this article experimental and numerical studies of internal frost resistance of self-compacting and normal concrete, with and without fibres, are outlined. For this purpose self-compacting concrete with low water-cement ratio was studied, with varying amounts of filler, crystalline or sedimentary, different pouring pressures and different mixing procedure with two ages at the start of testing. The concrete was frozen twice a day at ±20^∘C all around the specimen up to 300 cycles. Measurement of length, weight and internal fundamental frequency were performed at the start of testing, at 100 cycles and at 300 frost cycles. Tests were also carried out on submerged cast self-compacting concrete and on self-compacting concrete with fibres. In reference tests normal concrete was studied in parallel. In general self-compacting concrete behaved well or better than normal concrete to internal frost except for the submerged cast concrete, where large segregation occurred and low internal frost resistance followed. The main reasons for low internal frost resistance in submerged applications were probably differences in water-cement ratio in the casting due to cement, water or/and aggregate segregation. Polypropylene fibres in concrete seemed to prohibit the movement of water in the air void system so that a sudden internal collapse occurred before 300 frost cycles.     

Contradicting incentives for research collaboration

This study describes the Danish publication award system (BFI), investigates whether its built-in incentives have had an effect on publication behavior at the University of Southern Denmark, and discusses the possible future implications on researcher incentives should universities wish to measure BFI on the individual level. We analyzed publication data from the university CRIS system (Pure) and from SciVal. Several studies indicate that co-authored scholarly journal articles attract more citations than single author articles. The reason for this are not clear, however, research collaboration across institutions and countries is commonly accepted in the research community and among university managements as one way of increasing the researcher’s and institution’s reputation and impact. The BFI system is designed to award scholarly publication activity at Danish universities, especially publication in international journals of high status. However, we find that the built-in incentives leave the researcher and his or her institution with a dilemma: If the researchers optimize their performance by forming author groups with external collaborators, the optimal way of doing so for the researchers is not the optimal way seen from the perspective of the university. Our analysis shows that the typical article has 6.5 authors, two of which are internal, and that this has remained stable since the introduction of the BFI. However, there is variation across the disciplines. While ‘the Arts and Humanities’ and ‘the Social Sciences’ seem to compose author groups in a way which does not optimize the performance of the institution, both ‘Health’ and ‘the Natural Sciences’ seem to optimize according to criteria other than those specified in the BFI.     

Removal of estrogenicity in Swedish municipal sewage treatment plants

The human estrogen receptor alpha-test, hosted in a yeast strain, was used to quantify estrogenicity in three-week composite samples of untreated and treated effluents from 20 Swedish municipal sewage treatment plants. The treatment plants were selected to represent different treatment processes regarding chemical precipitation and microbial procedures. The discharge from Swedish domestic sewage treatment plants contained estrogenic compounds corresponding to <0.1-15 ng estradiol equivalents/L. Low levels of estrogenic activity were also found in a river receiving municipal effluents, 3.5-35 km downstream the outlet from a sewage treatment works. The range of estrogenicity in untreated, raw sewage effluents was found to be 1-30 ng estradiol equivalents/L. Generally, wastewater treatment reduced the estrogenicity and extended biological treatment was most effective in its removal. Activated sludge treatment tended to be more effective than trickling filters, whereas chemical precipitation using iron or aluminium salts without biological treatment showed little effectivity. The study showed that treatment methods in current use are able to eliminate or largely reduce estrogenicity in domestic wastewater.     

Debiasing overoptimistic beliefs about braking capacity

We investigated, using questionnaires, different strategies for removing drivers’ overoptimism (Svenson et al., 2012a) about how fast their speed could be decreased when they were speeding compared with braking at the speed limit speed. Three different learning groups and a control group made collision speed judgments. The first learning group had the distance a car travels during a driver's reaction time for each problem. The second group had this information and also feedback after each judgment (correct speed). The third group judged collision speed but also braking distance and received correct facts after each problem. The control group had no information at all about reaction time and the distance traveled during that time. The results suggested the following rank order from poor to improved performance: control, group 1, group 3 and group 2 indicating that information about distance driven during a driver's reaction time improved collision speed judgments and that adding stopping distance information did not add to this improvement.     

A homeobox gene with potential developmental control function in the meristem of the conifer Picea abies

Many homeobox genes control essential developmental processes in animals and plants. In this report, we describe the first cDNA corresponding to a homeobox gene isolated from a gymnosperm, the HBK1 gene from the conifer Picea abies (L.) Karst (Norway spruce). The sequence shows distinct similarities specifically to the KNOX (knotted-like homeobox) class of homeobox genes known from different angiosperm plants. The deduced amino acid sequence of HBK1 is strikingly similar within the homeodomain (84% identical) to the maize gene Knotted1 (Kn1), which acts to regulate cell differentiation in the shoot meristem. This similarity suggested that the phylogenetic association of HBK1 with the KNOX genes might be coupled to a conservation of gene function. In support of this suggestion, we have found HBK1 to be expressed in the apical meristem in the central population of nondifferentiated stem cells, but not in organ primordia developing at the flanks of the meristem. This pattern of expression is similar to that of Kn1 in the maize meristem. We show further that HBK1, when expressed ectopically in transgenic Arabidopsis plants, causes aberrations in leaf development that are similar to the effects of ectopic expression of angiosperm KNOX genes on Arabidopsis development. Taken together, these data suggest that HBK1 has a role, similar to the KNOX genes in angiosperms, in the control of cellular differentiation in the apical meristem of spruce. The data also indicate that KNOX-gene regulation of vegetative development is an ancient feature of seed plants that was present in the last common ancestor of conifers and angiosperms.