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Verdes, A., et al.
(author)
Molecular phylogeny and evolution of bioluminescence in Odontosyllis (Annelida, Syllidae)
2022
In: Invertebrate Systematics. - : CSIRO Publishing. - 1445-5226. ; 36:7, s. 622-630
Journal article (peer-reviewed) abstract
Marine worms of the genus Odontosyllis (Syllidae, Annelida) are well known for spectacular bio-luminescent courtship rituals. During the reproductive period, the benthic marine worms leave the ocean floor and swim to the surface to spawn, using bioluminescent light for mate attraction. The behavioural aspects of the courtship ritual have been extensively investigated but little is known about the origin and evolution of light production in Odontosyllis that may be a key factor shaping the natural history of the group. To investigate the speciation patterns and evolutionary history of Odontosyllis, we inferred phylogenies following a gene concatenation approach using both maximum likelihood and Bayesian inference with a multilocus molecular dataset including nuclear (18S rRNA) and mitochondrial markers (16S rRNA and cytochrome c oxidase subunit I) from 51 Odontosyllis specimens. We also used the resulting phylogenetic tree to perform an ancestral state reconstruction analysis to trace the origin of bioluminescence within the group. Our results reveal that the genus Odontosyllis as currently delineated is a paraphyletic group that needs to be taxonomically revised to reflect evolutionary relationships. Nevertheless, our analyses recover two supported clades with bioluminescent species and suggest that the most recent common ancestor of luminous syllids was not bioluminescent, providing evidence that bioluminescence has evolved independently twice in the group. We discuss possible scenarios for the origin and evolution of light production and the potential role of bioluminescence courtship as a driver of speciation. Our results shed light on the evolutionary history of luminous syllids and suggest that bioluminescence might represent a key factor shaping the evolution of these organisms.
4.
Danermark, Berth, et al.
(author)
Att förklara samhället
1997
Book (peer-reviewed) abstract
Att förklara samhället är en bok i metodologi. Med den kritiska realismen som grund presenterar författarna metodologiska riktlinjer för en samhällsvetenskap med höga anspråk på att kunna förklara samhälleliga förhållanden.Bokens nio kapitel behandlar samhällsvetenskapens ontologiska och epistemologiska grunder, begreppsbildning och strukturell analys, kausalitet och förklaring, samhällsvetenskapen som tolkande vetenskap, förhållandet mellan struktur och aktör, olika former av slutledningar och tankeoperationer, relationen mellan det generella och det individuella, teoriers betydelse i forskningspraktiken, olika sätt att koppla teori och empiri, kombinationer av metoder (det som i boken kallas kritisk metodpluralism) samt grunderna för en samhällsrelevant samhällsvetenskap.Kritiken mot de positivistiska vetenskapsidealen, empirismen och tron på den objektiva, bevisade kunskapen har delvis slagit över i sin motsats, en överdriven försiktighet, en långtgående relativism, en betoning på vad vetenskapen inte kan göra i stället för vad den kan göra. Denna bok visar att det finns ett fruktbart alternativ till dessa positioner, ett alternativ som ger mer realistiska och samtidigt konstruktiva grunder för samhällsvetenskaplig forskning.
5.
Boezio, Mirko, et al.
(author)
The electron-hadron separation performance of the PAMELA electromagnetic calorimeter
2006
In: Astroparticle physics. - : Elsevier BV. - 0927-6505 .- 1873-2852. ; 26:2, s. 111-118
Conference paper (peer-reviewed) abstract
A silicon-tungsten sampling imaging calorimeter has been designed and built for thePAMELA satellite-borne experiment. The main physics goals of the experiment are themeasurement of the flux of antiprotons (80 MeV-190 GeV) and positrons (50 MeV-270 GeV) in the cosmic radiation. The calorimeter has been designed to identify antiprotons from an electron background and positrons in a background of protons with a high efficiency and rejection power. This work presents the electron-hadron separationcapabilities of the calorimeter as obtained using both Monte Carlo and test beam data.The calorimeter is found to have sufficient performance to reach the primary scientific objectives of PAMELA, providing a proton rejection factor of ∼105 while keeping a ∼90% efficiency in selecting electrons and positrons. From simulations, an electron rejection factor of ∼105 in antiproton measurements (∼90% antiproton identification efficiency) is demonstrated.
6.
Pirmoradian, Roghayeh, et al.
(author)
Performance evaluation of IMERG and TMPA daily precipitation products over CONUS (2000–2019)
2022
In: Atmospheric Research. - : Elsevier BV. - 0169-8095. ; 279
Journal article (peer-reviewed) abstract
Ground validation of satellite-based precipitation products is necessary to evaluate the performance of satellite observation at local, regional, and global scales. The evaluation of the rainfall data accuracy will reveal both its strengths and weaknesses, thereby determining its suitability for hydrometeorological applications. To reach this goal, this study comprehensively evaluated and characterized the systematic bias in the Global Precipitation Measurement (GPM) Integrated Multi-SatellitE Retrievals for GPM (IMERG) precipitation product, to be compared with its predecessor Tropical Rainfall Measuring Mission (TRMM) Multi-satellite Precipitation Analysis (TMPA), based on the wide-spread ground-based observation data, PRISM (Parameter-Elevation Regression on Independent Slopes Model) over the Conterminous United States. The evaluation was conducted for daily datasets from June 2000 to the end of December 2019, in which IMERG and TMPA overlap using statistical error metrics both in space and time. While some statistical measures do not show significant improvement in daily IMERG compared to TMPA, systematic bias is substantially diminished. We detected systematic bias related to the vertical relief for both IMERG and TMPA but with a substantial decrease in the IMERG. The systematic bias in both satellite products distinctively differs in the summer and winter seasons, but, both products showed high performance in summer. According to our findings, the spatiotemporal performance of the IMERG precipitation product varies in different seasons, regions, time scales, and topographic conditions but with superiority over the TMPA daily product.
7.
van der Zwaag, B.J., et al.
(author)
Extracting Knowledge from Neural Networks in Image Processing
2003
In: Innovations in Knowledge Engineering. ; , s. 107-127
Book chapter (other academic/artistic) abstract
Despite their success-story, artificial neural networks have one major disadvantagecompared to other techniques: the inability to explain comprehensively how a trainedneural network reaches its output; neural networks are not only (incorrectly) seen as a “magic tool” but possibly even more as a mysterious “black box.” Although much research has already been done to “open the box,” there is a notable hiatus in known publications on analysis of neural networks. So far, mainly sensitivity analysis and rule extraction methods have been used to analyze neural networks. However, these can only be applied in a limited subset of the problem domains where neural network solutions are encountered. In this chapter we propose a wider applicable method which, for a given problem domain, involves identifying basic functions with which users in that domain are already familiar, and describing trained neural networks, or parts thereof, in terms of those basic functions. This will provide a comprehensible description of the neural network’s function and, depending on the chosen base functions, it may also provide an insight into the neural network’s inner “reasoning.” To illustrate our method, the elements of a feedforward-backpropagation neural network, that has been trained to detect edges in images, are described in terms of differential operators of various orders and with various angles of operation. The results are then compared with image filters known from literature, which we analyzed in the same way.
8.
Fedchenko, Maria, 1988
(author)
Cardiovascular disease in patients with congenital heart disease
2020
Doctoral thesis (other academic/artistic) abstract
Background: Today, about 95% of children with congenital heart disease (CHD) survive into adulthood and the survival in patients with CHD has increased considerably during the last decades. With increasing age, patients with CHD are at an increased risk of developing acquired cardiovascular disease, such as ischemic heart disease and myocardial infarction (MI). The overall aim of this thesis was to study ischemic heart disease and MI in patients with CHD, and to assess the prevalence of modifiable cardiovascular risk factors in patients with coarctation of the aorta (CoA). Methods: In paper I, III and IV we used the Swedish National Patient Register and the Cause of Death Register. In Paper I, 21,982 children and young adults with CHD born in 1970-1993 were followed until December 2011. In Paper IV, 17,189 patients with CHD ≥ 40 years of age, born in 1930 to 1970, were followed during the years 1970-2017. Each patient with CHD was matched by age and sex with ~10 controls from the total population register. Kaplan Meier and Cox regression analyses were used to calculate the cumulative incidence and hazard ratios for ischemic heart disease/MI in patients with CHD compared with controls. In Paper III we validated the MI diagnoses in patients with CHD by performing a medical chart review. In Paper II, a structured assessment of the prevalence of modifiable cardiovascular risk factors in 72 patients with CoA was performed, including oral glucose tolerance test and cholesterol levels. Results: The risk of ischemic heart disease was 16.5 times higher in children and young adults with CHD than in controls, and also the risk of MI was higher in middle aged and older patients with CHD compared with controls. However, the relative risk compared with controls was markedly higher in younger patients with CHD than in older patients with CHD (Papers I and IV). Most of the MI diagnoses in patients with CHD were correct (Paper III). Almost 9 out of 10 patients with CoA had at least one modifiable cardiovascular risk factor. Conclusion: The risk of ischemic heart disease and MI is increased in patients with CHD compared with controls; however, the mechanisms behind the increased risk may differ between younger and older patients with CHD. Modifiable cardiovascular risk factors are common in patients with CoA and a structured assessment of these should be considered to reduce the burden of atherosclerotic disease in CHD patients.
