Exploring Transition from Stability to Chaos through Random Matrices

This study explores the application of random matrices to track chaotic dynamics within the Chirikov standard map. Our findings highlight the potential of matrices exhibiting Wishart-like characteristics, combined with statistical insights from their eigenvalue density, as a promising avenue for chaos monitoring. Inspired by a technique originally designed for detecting phase transitions in spin systems, we successfully adapt and apply it to identify analogous transformative patterns in the context of the Chirikov standard map. Leveraging the precision previously demonstrated in localizing critical points within magnetic systems in our prior research, our method accurately pinpoints the Chirikov resonance-overlap criterion for the chaos boundary at $K\approx 2.43$, reinforcing its effectiveness.Comment: 10 pages, 6 figure

Rheumatoid arthritis, multiple sclerosis and lupus: key points from the COVID-19 era

The purpose of this work was to analyse published data on rheumatoid arthritis (RA), systemic lupus erythematosus (SLE) and multiple sclerosis (MS) and SARS-CoV-2 infection: susceptibility, post-infection autoimmune disease (AD) exacerbation, immunosuppressive therapies and long COVID. Supported by PICO strategy, two independent reviewers conducted the research in the PubMed/Medline database from January 2020 to June 2022 and included 16 articles on RA, 25 on MS and 12 on SLE. The quality assessment of the studies was performed using criteria from the National Institute of Health. Patients with RA or SLE had increased susceptibility to contracting SARS-CoV-2. It was higher in RA and increased with the patients’ comorbidities. For MS, susceptibility to SARS-CoV-2 was similar to the general population. Post-infection AD exacerbation occurred in AR, SLE and MS with an increased number of hospitalisations and deaths. Regarding therapies, in RA the use of glucocorticoids (GC) was associated with a worsening of the infection. A more severe clinical picture was associated with anti-CD20 in SLE and with anti-CD20 and methylprednisolone in MS. Considering long COVID, RA and SLE patients had a higher risk of complications opposite to MS patients. There was a higher susceptibility to SARS-CoV-2 infection in rheumatological diseases AR and SLE, exacerbated by age and comorbidities. For RA and MS, GC aggravated the infection and for SLE and MS anti-CD20 antibodies use. In all AD there was exacerbation and worsening of the clinical picture translated in long COVID, the latter with MS exception

A Simple Non-Markovian Computational Model of the Statistics of Soccer Leagues: Emergence and Scaling effects

We propose a novel algorithm that outputs the final standings of a soccer league, based on a simple dynamics that mimics a soccer tournament. In our model, a team is created with a defined potential(ability) which is updated during the tournament according to the results of previous games. The updated potential modifies a teams' future winning/losing probabilities. We show that this evolutionary game is able to reproduce the statistical properties of final standings of actual editions of the Brazilian tournament (Brasileir\~{a}o). However, other leagues such as the Italian and the Spanish tournaments have notoriously non-Gaussian traces and cannot be straightforwardly reproduced by this evolutionary non-Markovian model. A complete understanding of these phenomena deserves much more attention, but we suggest a simple explanation based on data collected in Brazil: Here several teams were crowned champion in previous editions corroborating that the champion typically emerges from random fluctuations that partly preserves the gaussian traces during the tournament. On the other hand, in the Italian and Spanish leagues only a few teams in recent history have won their league tournaments. These leagues are based on more robust and hierarchical structures established even before the beginning of the tournament. For the sake of completeness, we also elaborate a totally Gaussian model (which equalizes the winning, drawing, and losing probabilities) and we show that the scores of the "Brasileir\~{a}o" cannot be reproduced. Such aspects stress that evolutionary aspects are not superfluous in our modeling. Finally, we analyse the distortions of our model in situations where a large number of teams is considered, showing the existence of a transition from a single to a double peaked histogram of the final classification scores. An interesting scaling is presented for different sized tournaments.Comment: 18 pages, 9 figure

Thermodynamics on the spectra of random matrices

We show that the spectra of Wishart matrices built from magnetization time series can describe the phase transitions and the critical phenomena of the Potts model with a different number of states. We can statistically determine the transition points, independent of their order, by studying the density of the eigenvalues and corresponding fluctuations. In some way, we establish a relationship between the actual thermodynamics with the spectral thermodynamics described by the eigenvalues. The histogram of correlations between time series interestingly supports our results. In addition, we present an analogy to the study of the spectral properties of the Potts model, considering matrices correlated artificially. For such matrices, the eigenvalues are distributed in two groups that present a gap depending on such correlation.Comment: 10 pages, 11 figure

Sensorimotor synchronization when walking side by side with a point light walker

[Excerpt] Synchronization of periodic movements like side-by-side walking [7] is frequently modeled by coupled oscillators [5] and the coupling strength is defined quantitatively [3]. In contrast, in most studies on sensorimotor synchronization (SMS), simple movements like finger taps are synchronized with simple stimuli like metronomes [4]. While the latter paradigm simplifies matters and allows for the assessment of the relative weights of sensory modalities through systematic variation of the stimuli [1], it might lack ecological validity. Conversely, using more complex movements and stimuli might complicate the specification of mechanisms underlying coupling. We merged the positive aspects of both approaches to study the contribution of auditory and visual information on synchronization during side-by-side walking. As stimuli, we used Point Light Walkers (PLWs) and auralized steps sound; both were constructed from previously captured walking individuals [2][6]. PLWs were retro-projected on a screen and matched according to gender, hip height, and velocity. The participant walked for 7.20m side by side with 1) a PLW, 2) steps sound, or 3) both displayed in temporal congruence. Instruction to participants was to synchronize with the available stimuli. [...]Acknowledgments: [Supported by Fundação Bial (Grant 77/12) and Fundação para a Ciência e Tecnologia - FCT: SFRH/BD/88396/2012; EXPL/MHC-PCN/0162/2013; FCOMP-01-0124 - FEDER-022674 and PEst-C/CTM/U10264/2011; FCOMP-01-0124-FEDER-037281 and PEstC/EEI/LA0014/2013. This work was financed by FEDER grants through the Operational Competitiveness Program – COMPETE]

Contribution of the solar systems to the nZEB and ZEB design concept in Portugal: energy, economics and environmental life-cycle analysis

The recast of the Energy Performance of Buildings Directive settle that by 2020 all new buildings should reach nearly zero energy levels (2018 for buildings owned or occupied by public authorities). Therefore, technicians involved in the design, management and approval of buildings should be able to understand and apply nearly zero energy buildings (nZEB) concepts in both new buildings and refurbishment of existing ones. At European Union (EU) level there are differences in commitment to the EU targets and the construction of nZEB. Therefore, it is necessary to develop studies that demonstrate the advantages of the nZEB and ZEB design process that can increase the awareness of both building clients and other stakeholders regarding this issue. In this context, the aim of this paper is to assess the energy and environmental life-cycle performance of different renovation scenarios (Basic Renovation, nZEB and ZEB) for multifamily buildings in Portugal. This will be focused on the goals of the nZEB and ZEB design process and on the contribution of solar systems (both solar thermal collectors, STCs, and photovoltaic panels, PVs) to the achievement of those goals. The results presented in this paper show that, in the Portuguese climate and for a typical multi-family building, it is possible to overcome 100% of the energy needs for acclimatization and domestic hot water (DHW) preparation with the integration of solar systems. From the results, it is also possible to conclude that a significant amount of energy and carbon emissions are avoided for every renovation scenario during the considered lifetime (30 years) and that the nZEB and ZEB scenarios are cost-effective with attractive payback times.IEE Project SouthZEB (under the reference IEE/13/393)Portuguese Foundation for Science and Technology (FCT) in the framework of the Strategic Projects UID/ECI/04047/2013 and UID/FIS/04650/201

Influência das condições climáticas na fenologia do pessegueiro cv. 'Royal Time'

A fenologia estuda a morfologia dos diferentes estados do desenvolvimento das plantas e permite entender e datar o seu desenvolvimento, sendo particularmente importante nas espécies frutícolas, designadamente para o posicionamento das técnicas culturais a realizar ao longo do ciclo anual. Nas prunóideas de clima temperado, nas quais se inclui o pessegueiro, a cerejeira, a ameixeira e a amendoeira, o ciclo anual inicia-se com o desabrochamento dos gomos florais, que se vão desenvolvendo até atingir a plena floração. A chegada de pólen compatível ao estigma da flor pode conduzir à sua fertilização culminando no vingamento dos frutos. Este período de floração é condicionado pelo clima e é utilizado como indicador das alterações climáticas, sendo fundamental para entender como as plantas respondem a estas alterações, preocupação crescente por parte dos produtores devido ao aumento da frequência e intensidade de eventos climáticos extremos. Com o objetivo de estudar a influência das condições meteorológicas no período de floração em pessegueiros da Região da Beira Interior, foi observada a fenologia da cultivar Royal Time, num mesmo pomar, nos ciclos 2015, 2016 e 2018. Paralelamente, foi recolhida informação das variáveis climáticas temperatura e precipitação. Os resultados permitiram observar que, no ciclo 2015, o período de floração, desde o estado C ao estado G foi muito curto, de aproximadamente 17 dias, com a plena floração a ocorrer em 12 de março. Em 2016 o período de floração teve a duração de 36 dias, com a plena floração em 24 de março e em 2018 o período de floração estendeu-se por 35 dias, com a plena floração em 29 de março. Este estudo visa não só evidenciar a irregularidade climática que se observou nos últimos anos, como também contribuir para fornecer aos produtores informação quantificada sobre o efeito da irregularidade dos fatores climáticos na fenologiainfo:eu-repo/semantics/publishedVersio

Gut bacteria responding to dietary change encode sialidases that exhibit preference for red meat-associated carbohydrates.

Dietary habits have been associated with alterations of the human gut resident microorganisms contributing to obesity, diabetes and cancer1. In Western diets, red meat is a frequently eaten food2, but long-term consumption has been associated with increased risk of disease3,4. Red meat is enriched in N-glycolylneuraminic acid (Neu5Gc) that cannot be synthesized by humans5. However, consumption can cause Neu5Gc incorporation into cell surface glycans6, especially in carcinomas4,7. As a consequence, an inflammatory response is triggered when Neu5Gc-containing glycans encounter circulating anti-Neu5Gc antibodies8,9. Although bacteria can use free sialic acids as a nutrient source10-12, it is currently unknown if gut microorganisms contribute to releasing Neu5Gc from food. We found that a Neu5Gc-rich diet induces changes in the gut microbiota, with Bacteroidales and Clostridiales responding the most. Genome assembling of mouse and human shotgun metagenomic sequencing identified bacterial sialidases with previously unobserved substrate preference for Neu5Gc-containing glycans. X-ray crystallography revealed key amino acids potentially contributing to substrate preference. Additionally, we verified that mouse and human sialidases were able to release Neu5Gc from red meat. The release of Neu5Gc from red meat using bacterial sialidases could reduce the risk of inflammatory diseases associated with red meat consumption, including colorectal cancer4 and atherosclerosis13