Search results for " hypothesis"
showing 10 items of 371 documents
Degenerate Riemann theta functions, Fredholm and wronskian representations of the solutions to the KdV equation and the degenerate rational case
2021
International audience; We degenerate the finite gap solutions of the KdV equation from the general formulation given in terms of abelian functions when the gaps tend to points, to get solutions to the KdV equation given in terms of Fredholm determinants and wronskians. For this we establish a link between Riemann theta functions, Fredholm determinants and wronskians. This gives the bridge between the algebro-geometric approach and the Darboux dressing method.We construct also multi-parametric degenerate rational solutions of this equation.
Knowledge Discovery from the Programme for International Student Assessment
2017
The Programme for International Student Assessment (PISA) is a worldwide study that assesses the proficiencies of 15-year-old students in reading, mathematics, and science every three years. Despite the high quality and open availability of the PISA data sets, which call for big data learning analytics, academic research using this rich and carefully collected data is surprisingly sparse. Our research contributes to reducing this deficit by discovering novel knowledge from the PISA through the development and use of appropriate methods. Since Finland has been the country of most international interest in the PISA assessment, a relevant review of the Finnish educational system is provided. T…
Ecological determinants of smart home ecosystems: A coopetition framework
2021
Abstract Nearly every industry classification is experiencing slow growth and increasing concentration. Seldom do researchers have an opportunity to observe an emerging industry segment with as much promise as the smart home ecosystem, an exponentially growing industry. The study presents a novel approach using industry life cycle model and a coopetition framework to understand the process of the ecosystem development. Building on recent literature suggesting companies that purposefully match strategy to life cycle stage, the paper describes the strategic motivations and critical factors involved in the competition-based evolution of smart home ecosystems from early to growth phases, leadin…
Hypoxia and hypothermia as rival agents of selection driving the evolution of viviparity in lizards
2017
[Aim]: The evolution of key innovations promotes adaptive radiations by opening access to new ecological opportunity. The acquisition of viviparity (live-bearing reproduction) has emerged as one such innovation explaining reptile proliferations into extreme climates. By evolving viviparity, females provide embryos with internally stable environments to complete development. The classical hypothesis suggests that natural selection for viviparity arises from low temperatures in cold climates, which promote prolonged egg retention in the mother's body. An alternative hypothesis proposes that declines in atmospheric oxygen at high elevations create natural selection for embryo retention to prov…
Absence of Sex Differential Plasticity to Light Availability during Seed Maturation in Geranium sylvaticum
2015
Sex-differential plasticity (SDP) hypothesis suggests that since hermaphrodites gain fitness through both pollen and seed production they may have evolved a higher degree of plasticity in their reproductive strategy compared to females which achieve fitness only through seed production. SDP may explain the difference in seed production observed between sexes in gynodioecious species in response to resource (nutrients or water) availability. In harsh environments, hermaphrodites decrease seed production whereas females keep it relatively similar regardless of the environmental conditions. Light availability can be also a limiting resource and thus could theoretically affect differently femal…
Getting rid of the Chi-square and Log-likelihood tests for analysing vocabulary differences between corpora
2018
Log-likelihood and Chi-square tests are probably the most popular statistical tests used in corpus linguistics, especially when the research is aiming to describe the lexical variations between corpora. However, because this specific use of the Chi-square test is not valid, it produces far too many significant results. This paper explains the source of the problem (i.e., the non-independence of the observations), the reasons for which the usual solutions are not acceptable and which kinds of statistical test should be used instead. A corpus analysis conducted on the lexical differences between American and British English is then reported, in order to demonstrate the problem and to confirm …
Mesocarnivore community structuring in the presence of Africa's apex predator
2021
This work was supported by the Peace Parks Foundation; G.C.S. was funded by a doctoral grant from Fundacão para a Ciência e a Tecnologia (FCT: PD/BD/114037/2015); L.H.S. was supported by the National Research Foundation, South Africa (UID: 107099 and 115040) and by the African Institute for Conservation Ecology. Apex predator reintroductions have proliferated across southern Africa, yet their ecological effects and proposed umbrella benefits of associated management lack empirical evaluations. Despite a rich theory on top-down ecosystem regulation via mesopredator suppression, a knowledge gap exists relating to the influence of lions (Panthera leo) over Africa's diverse mesocarnivore (less …
Parental experience of a risky environment leads to improved offspring growth rate.
2014
Abstract Parasites (or diseases) are major selective force for the evolution of life history traits and parasite-host evolution. Mothers can show a variety of responses to parasites during pregnancy with different consequences for them or their offspring. However, whether information in the maternal environment before pregnancy can cause a change in the phenotype of the offspring is unknown. To avoid the confounding effect of pathogens and to reduce the risk of direct effect of mother's immune activation, we injected female laboratory mice with lipopolysaccharides (LPS) before mating. In order to provide a constant information on the potential infectious risk of the environment, females wer…
Regulation of T cells in asthma: implications for genetic manipulation
2004
PURPOSE OF THE REVIEW Allergic asthma is a disease characterized by airway hyperresponsiveness, inflammation and remodeling. In the past few decades it has become clear that the pathogenesis and development of this disease is controlled by cytokines released by CD4 T helper type 2 lymphocytes that develop under the influence of natural killer lymphocytes. At birth, T cell priming exhibits a T helper type 2 bias and the development of the T helper phenotype is determined in the first year of life by environmental exposure to virus or bacterial substances or environmental allergens in genetically predisposed individuals. Decreased exposure to infection in early childhood has thus been linked …
Threshold cointegration and nonlinear adjustment between goods and services inflation in the United States
2006
In this paper, we model the long-run relationship between goods and services inflation for the United States over the period 1968:1–2003:3. Our empirical methodology makes use of recent developments on threshold cointegration that consider the possibility of a nonlinear relationship between the two inflation series. According to our results, the null hypothesis of linear cointegration would be rejected in favor of a two-regime threshold cointegration model. Consequently, we could expect a cointegrating relationship only when the divergence between services inflation and goods inflation is above the threshold point estimate.