125 research outputs found
Wastewater resource recovery with green microalgae – modelling the microalgal growth, nutrient uptake and storage using ASM-A
Scattering statistics of rock outcrops: Model-data comparisons and Bayesian inference using mixture distributions
The probability density function of the acoustic field amplitude scattered by
the seafloor was measured in a rocky environment off the coast of Norway using
a synthetic aperture sonar system, and is reported here in terms of the
probability of false alarm. Interpretation of the measurements focused on
finding appropriate class of statistical models (single versus two-component
mixture models), and on appropriate models within these two classes. It was
found that two-component mixture models performed better than single models.
The two mixture models that performed the best (and had a basis in the physics
of scattering) were a mixture between two K distributions, and a mixture
between a Rayleigh and generalized Pareto distribution. Bayes' theorem was used
to estimate the probability density function of the mixture model parameters.
It was found that the K-K mixture exhibits significant correlation between its
parameters. The mixture between the Rayleigh and generalized Pareto
distributions also had significant parameter correlation, but also contained
multiple modes. We conclude that the mixture between two K distributions is the
most applicable to this dataset.Comment: 15 pages, 7 figures, Accepted to the Journal of the Acoustical
Society of Americ
Improving stability and understandability of genotype-phenotype mapping in Saccharomyces using regularized variable selection in L-PLS regression
Perceptions of Harms Associated With Tobacco, Alcohol, and Cannabis Among Students From the UK and Norway
Introduction: International drug policy has traditionally been based on the premise that illegal drugs are more harmful than legal substances. Here, we investigate how students in the UK and Norway now perceive possible harms related to tobacco and alcohol—which are legal—and cannabis—which is illegal.
Methods: Social science undergraduates at a university in the UK (n = 473) and Norway (n = 472) completed an anonymous survey. They were asked to rate the harms of tobacco, alcohol, and cannabis across five domains: (i) physical harms, (ii) mental health conditions, (iii) dependence, (iv) injuries, and (v) social consequences. Bivariate and multivariate analyses were used to compare the relative harms of the three substances across all the domains as well as possible differences between participants from the UK and Norway.
Results: Tobacco was rated as most harmful with regard to physical harm and dependence; alcohol was rated as most harmful with regard to injuries and social consequences, while cannabis was rated as most harmful with regard to mental health. The total harms scores for alcohol were highest, slightly above those of cannabis. British students reported higher tobacco and alcohol harm scores than Norwegian students, while the opposite pattern was true for cannabis.
Conclusions: The legal substance alcohol was rated by students as more harmful than the illegal substance cannabis. The findings may imply that young people in the years to come may be less supportive of a traditional drug policy based on criminalization, at least when it comes to cannabis. At the same time, one may hypothesize that liberal alcohol policies may receive little support, given students’ perception of the possible harms associated with alcohol
BETWEEN BROADCASTING POLITICAL MESSAGES AND INTERACTING WITH VOTERS
Politicians across Western democracies are increasingly adopting and experimenting with Twitter, particularly during election time. The purpose of this article is to investigate how candidates are using it during an election campaign. The aim is to create a typology of the various ways in which candidates behaved on Twitter. Our research, which included a content analysis of tweets (n = 26,282) from all twittering Conservative, Labour and Liberal Democrat candidates (n = 416) during the 2010 UK General Election campaign, focused on four aspects of tweets: type, interaction, function and topic. By examining candidates' twittering behaviour, the authors show that British politicians mainly used Twitter as a unidirectional form of communication. However, there were a group of candidates who used it to interact with voters by, for example, mobilizing, helping and consulting them, thus tapping into the potential Twitter offers for facilitating a closer relationship with citizens
Mining for genotype-phenotype relations in Saccharomyces using partial least squares
<p>Abstract</p> <p>Background</p> <p>Multivariate approaches are important due to their versatility and applications in many fields as it provides decisive advantages over univariate analysis in many ways. Genome wide association studies are rapidly emerging, but approaches in hand pay less attention to multivariate relation between genotype and phenotype. We introduce a methodology based on a BLAST approach for extracting information from genomic sequences and Soft- Thresholding Partial Least Squares (ST-PLS) for mapping genotype-phenotype relations.</p> <p>Results</p> <p>Applying this methodology to an extensive data set for the model yeast <it>Saccharomyces cerevisiae</it>, we found that the relationship between genotype-phenotype involves surprisingly few genes in the sense that an overwhelmingly large fraction of the phenotypic variation can be explained by variation in less than 1% of the full gene reference set containing 5791 genes. These phenotype influencing genes were evolving 20% faster than non-influential genes and were unevenly distributed over cellular functions, with strong enrichments in functions such as cellular respiration and transposition. These genes were also enriched with known paralogs, stop codon variations and copy number variations, suggesting that such molecular adjustments have had a disproportionate influence on <it>Saccharomyces </it>yeasts recent adaptation to environmental changes in its ecological niche.</p> <p>Conclusions</p> <p>BLAST and PLS based multivariate approach derived results that adhere to the known yeast phylogeny and gene ontology and thus verify that the methodology extracts a set of fast evolving genes that capture the phylogeny of the yeast strains. The approach is worth pursuing, and future investigations should be made to improve the computations of genotype signals as well as variable selection procedure within the PLS framework.</p
Behavioral and Physiological Responses of Scandinavian Brown Bears (Ursus arctos) to Dog Hunts and Human Encounters
Innovations in biologging have offered new possibilities to better understand animals in their natural environment. Biologgers can be used by researchers to measure the impact of human disturbances on wildlife and guide conservation decisions. In this study, the behavioral and physiological responses of brown bears (Ursus arctos) to hunts using dogs (Canis lupus familiaris) and human encounters were assessed to better understand the impact of human outdoor activities on brown bears. In Scandinavia, brown bear hunting and the use of dogs during hunts is increasing in popularity. Nonetheless, not every hunt leads to a killed bear. This means that for each bear that is shot, multiple bears may be chased but not killed. In addition, bears can also be disturbed when encountering non-hunting humans. Heart rates, body temperatures, GPS coordinates and dual-axis activity data were collected from 52 simulated hunts (a simulated hunt using dogs with the bear allowed to flee at the end) and 70 human encounters (humans intentionally approaching the bear) that were carried out on 28 free-ranging female brown bears in two study areas in Sweden. The results showed that: (1) simulated hunts had a greater impact and induced a greater energy cost than human encounters; (2) the amount of time bears rested the day after the simulated hunts increased linearly with the duration of the simulated hunts, implying a lasting behavioral impact relative to the intensity of the disturbance. Although not tested in this study, brown bears that are repeatedly disturbed by dog hunts and human encounters may be unable to compensate the disturbances' energy cost, and their fitness may, therefore, be altered. If it is the case, this effect should be accounted for by managers
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