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Ana Firanj Sremac

Publications and source records attributed to Ana Firanj Sremac.

3 recordsLinked to original sources

Modelling Mosquito Population Dynamics using PINN-derived Empirical Parameters

Vector-borne diseases continue to pose a significant health threat globally with more than 3 billion people at risk each year. Despite some limitations, mechanistic dynamic models are a popular approach to representing biological processes using ordinary differential equations where the parameters describe the different development and survival rates. Recent advances in population modelling have seen the combination of these mechanistic models with machine learning. One approach is physics-informed neural networks (PINNs) whereby the machine learning framework embeds physical, biological, or chemical laws into neural networks trained on observed or measured data. This enables forward simulations, predicting system behaviour from given parameters and inputs, and inverse modelling, improving parameterisation of existing parameters and estimating unknown or latent variables. In this paper, we focus on improving the parameterisation of biological processes in mechanistic models using PINNs to determine inverse parameters. In comparing mechanistic and PINN models, our experiments offer important insights into the strengths and weaknesses of both approaches but demonstrated that the PINN approach generally outperforms the dynamic model. For a deeper understanding of the performance of PINN models, a final validation was used to investigate how modifications to PINN architectures affect the performance of the framework. By varying only a single component at a time and keeping all other factors constant, we are able to observe the effect of each change.

physics.bio-ph↗

Redefining Influenza Transmission Seasonality Using the Novel Seasonality Index

The impact of climate conditions on influenza epidemiology has mostly been studied by addressing a singular aspect of transmission and a climate variable correlating to it. As climate change unfolds at an unprecedented rate, we urgently need new multidisciplinary approaches that can embrace complexity of disease transmission in the fast-changing environment and help us better understand the implications for health. In this study, we have implemented a novel seasonality index to capture a vast network of climate, infectious, and socio-behavioural mechanisms influencing a seasonal influenza epidemic. We hypothesize that intricate, region-specific behavioural patterns are cross regulating the influenza spreading and dynamics of epidemics with changes in meteorological conditions within a specific season. To better understand the phenomena, we analysed weekly surveillance data from temperate European countries and redefined seasonal transitions using the seasonality index. This approach allowed us to characterize influenza seasonality more accurately in relation to specific atmospheric conditions. Key findings include: i) a strong correlation between influenza infection rates and the seasonality index across different climate zones and social groups, and ii) a high linear correlation between winter duration, determined by the seasonality index, and the time scale of low-frequency peaks in the infection rates power spectral density.

q-bio.QM↗

Seasonal Changes -- Time for Paradigm Shift

Season and their transitions play a critical role in sharpening ecosystems and human activities, yet traditional classifications, meteorological and astronomical, fail to capture the complexities of biosphere-atmosphere interactions. Conventional definitions often overlook the interplay between climate variables, biosphere processes, and seasonal anticipation, particularly as global climate change disrupts traditional patterns. This study addresses the limitations of current seasonal classification by proposing a framework based on phenological markers such as NDVI, EVI, LAI, fPAR, and the Bowen ratio, using plants as a nature-based sensor of seasonal transitions. Indicators derived from satellite data and ground observations provide robust foundations for defining seasonal boundaries. The normalized daily temperature range (DTRT), validated in crop and orchard regions, is hypothesized as a reliable seasonality index to capture transitions. We demonstrated the alignment of this index with phenological markers across boreal, temperate, and deciduous forests. Analyzing trends, extreme values and inflection points in the seasonality index time series, we established a methodology to identify seasonal onset, duration, and transitions. This universal, scalable classification aligns with current knowledge and perception of seasonal shifts and captures site-specific timing. Findings reveal shifts in the Euro-Mediterranean region, with winters shortening, summers extending, and transitions becoming more pronounced. Effects include the Gulf Stream s influence on milder transitions, urban heat islands accelerating seasonal shifts, and large inland lakes moderating durations. This underscores the importance of understanding seasonal transitions to enable climate change adaptive strategies in agriculture, forestry, urban planning, medicine, trade, marketing, and tourism.

physics.ao-ph↗