Search results for "RAV"
showing 10 items of 5866 documents
A Neuro-Ethological Approach for the TSP: Changing Metaphors in Connectionist Models.
1994
Biological systems often offer solutions to difficult problems which are not only original but also efficient. Connectionist models have been inspired by neural systems and successfully applied to the formulation of algorithms for solving complex problems such as the travelling salesman problem. In this paper we extend the connectionist metaphor to include an ethological account of how problems similar to the travelling salesman problem are solved by real living systems. A model is presented in which a population of neural networks with simple sensory-motor systems evolve genetically in simulated environments which represent the problem instances to be solved. Preliminary results are discu…
2021
The COVID-19 pandemic and social distancing measures targeting the transmission of the virus impacted everyday life in 2020. This study investigated pre- to in-pandemic changes in health behaviors and depressive symptoms during the COVID-19 pandemic and the role of personality traits in these changes in Finland. Data from a larger population-based cohort study of 51–59-year-old Finnish women were used (n = 358). Self-reported questionnaires gathered information about depressive symptoms, eating behavior, physical activity, and alcohol consumption before the pandemic time, at the onset, and at the end of the COVID-19 emergency conditions. Information about personality traits (extraversion an…
Sex and population variation in ultraviolet reflectance of colour patches in Gallotia galloti (Fam. Lacertidae) from Tenerife (Canary Islands)
2005
Sex and population differences in the ultraviolet (UV) reflectance patterns of two phenotypically divergent lacertids from Tenerife, Gallotia galloti eisentrauti and G. g. galloti, are described. Adults in both populations have rows of lateral and ventro-lateral blue patches on either side of the trunk that show a single peak of reflectance in the near UV. The lateral patches of males are more intensely reflective than those of females, but females have more chromatic and UV-shifted lateral patches than males. Most G. g. eisentrauti and some G. g. galloti also have blue cheek patches on either side of the gular area. Male cheek patches have reflectance peaks in the near UV, whereas those of…
A Primer on Memetic Algorithms
2012
Memetic Algorithms (MAs) are population-based metaheuristics composed of an evolutionary framework and a set of local search algorithms which are activated within the generation cycle of the external framework, see [376]. The earliest MA implementation has been given in [621] in the context of the Travelling Salesman Problem (TSP) while an early systematic definition has been presented in [615]. The concept of meme is borrowed from philosophy and is intended as the unit of cultural transmission. In other words, complex ideas can be decomposed into memes which propagate andmutate within a population.Culture, in this way, constantly undergoes evolution and tends towards progressive improvemen…
First record of an established marbled crayfish Procambarus virginalis (Lyko, 2017) population in Estonia
2019
Invasive marbled crayfish Procambarus virginalis (Lyko, 2017) is spreading alarmingly fast across European countries and beyond. Early maturation, parthenogenetic reproduction mode and high growth rate contribute to a high potential invasiveness. Marbled crayfish can pose severe effects on native communities impacting the native crayfish populations being carrier of the crayfish plague disease caused by Aphanomyces astaci. Here we report the first record of marbled crayfish in Estonia. In total, 104 individuals were found in the artificially warm outflow channel of the cooling system of Balti Power Plant, entering to the water reservoir of the River Narva. Molecular analyses confirmed the m…
Aplicación de la espectroelectrogravimetria para el desarrollo de supercondensadores basados en PEDOT
2022
En la presente tesis doctoral, titulada Aplicación de la espectroelectroquímica para el desarrollo de supercondensadores basados en PEDOT, se pretende ahondar en el sistema PEDOT en medio acuoso. Dicho estudio se ha llevado a cabo haciendo uso de diferentes metodologías. Por un lado, los experimentos de video-digital RGB electroquímica (DVEC) han permitido optimizar el depósito a partir de la obtención de parámetros como la eficiencia electrocrómica y el contraste de color del sistema, concluyendo que el mejor depósito es el cronoamperométrico 1.1V, 15s en un medio acuoso 0.01M EDOT y 0.1M KNO3. Además, se presenta un estudio cinético del PEDOT basado en el estudio de la varianza de color d…
Relationships of temperature and biodiversity with stability of natural aquatic food webs
2023
Temperature and biodiversity changes occur in concert, but their joint effects on ecological stability of natural food webs are unknown. Here, we assess these relationships in 19 planktonic food webs. We estimate stability as structural stability (using the volume contraction rate) and temporal stability (using the temporal variation of species abundances). Warmer temperatures were associated with lower structural and temporal stability, while biodiversity had no consistent effects on either stability property. While species richness was associated with lower structural stability and higher temporal stability, Simpson diversity was associated with higher temporal stability. The responses of…
A New Method to Reconstruct Quantitative Food Webs and Nutrient Flows from Isotope Tracer Addition Experiments
2020
Understanding how nutrients flow through food webs is central in ecosystem ecology. Tracer addition experiments are powerful tools to reconstruct nutrient flows by adding an isotopically enriched element into an ecosystem and tracking its fate through time. Historically, the design and analysis of tracer studies have varied widely, ranging from descriptive studies to modeling approaches of varying complexity. Increasingly, isotope tracer data are being used to compare ecosystems and analyze experimental manipulations. Currently, a formal statistical framework for analyzing such experiments is lacking, making it impossible to calculate the estimation errors associated with the model fit, the…
Ekonomiskās diplomātijas, kā viena no eksporta ietekmējošajiem faktoriem, analīze: Latvijas gadījums
2021
Esošā zinātniskā literatūra ir parādījusi, ka starp eksportu un ekonomisko diplomātiju pastāv pozitīva saikne. Tādējādi, mēģinot samazināt starptautiskās tirdzniecības šķēršļus, lai palielinātu eksportu, ekonomiskā diplomātija var tikt uzskatīta par svarīgu instrumentu, lai to panāktu. Maģistra darba mērķis ir veikt ekonomiskās diplomātijas, kā vienu no eksporta ietekmējošajiem faktoriem analīzi, izmantojot tirdzniecības gravitācijas modeli. Pētījumā ir iekļauti dati par divdesmit valstīm laika posmā no 2009. līdz 2019. gadam. Darba pirmajā nodaļā tiek apskatīti eksportu ietekmējošie faktori, tostarp ekonomiskā diplomātija, un tirdzniecības gravitācijas modelis kā eksportu ietekmējošo fakto…
The effects of an 8-year individualised lifestyle intervention on food consumption and nutrient intake from childhood to adolescence: the PANIC Study.
2021
Abstract We aimed to investigate the effects of a long-term, individualised, family-based lifestyle intervention on food consumption and nutrient intake from childhood to adolescence. We conducted an 8-year diet and physical activity intervention study in a population sample of children aged 7–9 years at baseline in 2007–2009. We allocated the participants to the intervention group (n 306) and the control group (n 198). We assessed diet by 4-d food records at baseline, 2-year follow-up and 8-year follow-up. We analysed the data using linear mixed-effects models adjusted for age at baseline and sex. The consumption of vegetables and vegetable oil-based spreads (fat ≥60 %) increased in the in…