Search results for "VDP::Matematikk og Naturvitenskap: 400"
showing 10 items of 647 documents
A non-stationary relay-based 3D MIMO channel model with time-variant path gains for human activity recognition in indoor environments
2021
AbstractExtensive research showed that the physiological response of human tissue to exposure to low-frequency electromagnetic fields is the induction of an electric current in the body segments. As a result, each segment of the human body behaves as a relay, which retransmits the radio-frequency (RF) signal. To investigate the impact of this phenomenon on the Doppler characteristics of the received RF signal, we introduce a new three-dimensional (3D) non-stationary channel model to describe the propagation phenomenon taking place in an indoor environment. Here, the indoor space is equipped with a multiple-input multiple-output (MIMO) system. A single person is moving in the indoor space an…
On stability of linear dynamic systems with hysteresis feedback
2020
The stability of linear dynamic systems with hysteresis in feedback is considered. While the absolute stability for memoryless nonlinearities (known as Lure's problem) can be proved by the well-known circle criterion, the multivalued rate-independent hysteresis poses significant challenges for feedback systems, especially for proof of convergence to an equilibrium state correspondingly set. The dissipative behavior of clockwise input-output hysteresis is considered with two boundary cases of energy losses at reversal cycles. For upper boundary cases of maximal (parallelogram shape) hysteresis loop, an equivalent transformation of the closed-loop system is provided. This allows for the appli…
Categorising animals and habitats in disaster-related activities
2021
A disaster is typically defined as a situation requiring external assistance, under the (contestable) assumption that the situation must affect people and society to be a disaster. Animals and their habitats are part of society and humans connect with them, so animals and their habitats are part of all disaster-related activities. This straightforward statement has produced divergent theories, policies and practices including challenges to categories, labels and divisions for humans and non-humans. This paper collates many practitioner aspects regarding animals and habitats in disaster-related activities. It assists in understanding and training for situations involving non-humans before, d…
Consequences of single-locus and tightly linked genomic architectures for evolutionary responses to environmental change
2020
AbstractGenetic and genomic architectures of traits under selection are key factors influencing evolutionary responses. Yet, knowledge of their impacts has been limited by a widespread assumption that most traits are controlled by unlinked polygenic architectures. Recent advances in genome sequencing and eco-evolutionary modelling are unlocking the potential for integrating genomic information into predictions of population responses to environmental change. Using eco-evolutionary simulations, we demonstrate that hypothetical single-locus control of a life history trait produces highly variable and unpredictable harvesting-induced evolution relative to the classically applied multi-locus mo…
Crude oil exposures reveal roles for intracellular calcium cycling in haddock craniofacial and cardiac development.
2016
AbstractRecent studies have shown that crude oil exposure affects cardiac development in fish by disrupting excitation-contraction (EC) coupling. We previously found that eggs of Atlantic haddock (Melanogrammus aeglefinus) bind dispersed oil droplets, potentially leading to more profound toxic effects from uptake of polycyclic aromatic hydrocarbons (PAHs). Using lower concentrations of dispersed crude oil (0.7–7 μg/L ∑PAH), here we exposed a broader range of developmental stages over both short and prolonged durations. We quantified effects on cardiac function and morphogenesis, characterized novel craniofacial defects, and examined the expression of genes encoding potential targets underly…
Improving risk assessments in conservation ecology
2019
Conservation efforts and management decisions on the living environment of our planet often rely on the results from statistical models. Yet, these models are imperfect and quantification of risk associated with the estimate of management-relevant quantities becomes crucial in providing robust advice. Here we demonstrate that estimates of risk themselves could be substantially biased but by combining data fitting with an extensive simulation–estimation procedure, one can back-calculate the correct values. We apply the method to 627 time series of population abundance across four taxa using the Gompertz state-space model as an example. We find that the risk of large bias in population status…
Predicting the spatial abundance of Ixodes ricinus ticks in southern Scandinavia using environmental and climatic data
2019
AbstractRecently, focus on tick-borne diseases has increased as ticks and their pathogens have become widespread and represent a health problem in Europe. Understanding the epidemiology of tick-borne infections requires the ability to predict and map tick abundance. We measured Ixodes ricinus abundance at 159 sites in southern Scandinavia from August-September, 2016. We used field data and environmental variables to develop predictive abundance models using machine learning algorithms, and also tested these models on 2017 data. Larva and nymph abundance models had relatively high predictive power (normalized RMSE from 0.65–0.69, R2 from 0.52–0.58) whereas adult tick models performed poorly …
Facilitators and inhibitors of organic food buying behavior
2021
Abstract Consumption patterns across the globe indicate consumers’ rising interest in purchasing organic food due to increasing personal-health consciousness. However, research on organic food shows a low translation of this interest into stated preferences for purchasing organic food. Limited academic research has explored this puzzling buying behavior of consumers, particularly in developed economies such as Japan. Our study addresses this gap by examining the factors that facilitate or inhibit Japanese consumers’ buying behavior toward organic food. We use the Stimulus-Organism-Response framework, Innovation Resistance Theory, and Dual-Factor Theory to examine these factors by analyzing …
Intensified forestry as a climate mitigation measure alters surface water quality in low intensity managed forests
2020
Climate change has led to a focus on forest management techniques to increase carbon (C) sequestration as a mitigation measure. Fertilisation and increased removal of biomass have been proposed. But these and other forest practices may have undesirable effects on surface water quality. In naturally acid-sensitive areas such as much of Fennoscandia a concern is acidification due to acid deposition in combination with forest practices that increase the removal of base cations and leaching of nitrate (NO3). Here we apply the biogeochemical model MAGIC to the coniferous-forested catchment at Birkenes, southernmost Norway, to simulate the effects of forest fertilisation and harvest on soil and s…
Exposing Empirical Links between COVID-19 Situation Report and Available Data: The Case of Nigeria
2020
Ever since the index case of COVID-19 was announced in Nigeria, the number of confirmed cases has gradually increased to 46,140 (about 4.5% of total confirmed cases in Africa) as the time of writing this article. This seemingly low number of confirmed cases has provoked heated debates among researchers. This cross-sectional study explores the Nigerian COVID-19 report to expose some links between the number of confirmed cases, testing, and some environmental conditions. The findings reveal that there is no state in Nigeria which has up to 12 confirmed cases per 10,000 population. That means, the number of confirmed COVID-19 cases is less than 0.15% of the population of people across each sta…