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In the Chilean exchange rate market, composed by sophisticated institutional investors and under different models of intervention of Central Bank, it is possible to obtain abnormal returns with the use of technical analysis and autoregresive models. The findings are similar to those observed in other international markets, but they were not the expected by the authors, since the low number of participants in this market, the high volatility due to deep international financial crises and the significant changes in this market introduced by the Central Bank. In effect, in the last third of the sample, the volatility of the exchange rate increased significantly and the abnormal returns obtained under the technical analysis and autoregressive models were equivalent to 60% approximately of the total sample. This period corresponds to the decision of the Chilean Central Bank to intervene in the exchange rate market as a result of the economic crisis in Argentina. Also, we did not observed statistical difference between the exchange rate and the forecasted by the autoregressive models, result that was validated by parametric and nonparametric test. [ABSTRACT FROM AUTHOR]

Objective: Long COVID is a condition characterised by persistent symptoms after a SARS-CoV-2 infection, with neurological manifestations being particularly frequent. Existing research suggests that long COVID patients not only report cognitive symptoms but also exhibit measurable cognitive impairment. Neuroimaging studies have identified structural alterations in brain regions linked to cognitive functions. However, most of these studies have focused on patients within months of their initial infection. This study aims to explore the longer-term cognitive effects and brain structural changes in long COVID patients, approximately two years post-infection, in a cohort from San Martín, Buenos Aires, Argentina., Methods: We conducted a cross-sectional study involving 137 participants: 109 with long COVID symptoms and 28 healthy controls. The participants underwent an initial clinical assessment, completed a structured questionnaire and standardised scales, underwent a cognitive assessment, and had a brain MRI scan. Structural MRI images were processed via FreeSurfer and FSL to obtain volumetric measures for subcortical and cortical regions, along with regional cortical thickness. Differences between groups for these variables were analysed using ANCOVA, with permutation tests applied to correct for multiple comparisons., Results: Long COVID patients reported persistent cognitive symptoms such as memory problems and brain fog, with higher levels of fatigue and reduced quality of life compared to controls. Despite subjective cognitive complaints, cognitive tests did not reveal significant differences between groups, except for the TMT-A (p = 0.05). MRI analysis revealed decreased volume in the cerebellum (p = 0.03), lingual gyrus (p = 0.04), and inferior parietal regions (p = 0.03), and reduced cortical thickness in several areas, including the left and right postcentral gyri (p = 0.02, p = 0.03) and precuneus (p = 0.01, p = 0.02)., Conclusions: This study highlights the enduring impact of long COVID on quality of life and physical activity, with specific brain structural changes identified two years post-infection. Although cognitive tests did not show clear impairment, the observed brain atrophy and significant reduction in quality of life emphasize the need for comprehensive interventions and further longitudinal studies to understand the long-term effects of long COVID on cognition and brain health., Competing Interests: Declarations Ethics approval and consent to participate The study was approved by the HIGA Eva Peron Research Bioethics Committee (OHRP registration number IRB00002792). All subjects provided written informed consent. All methods were performed in accordance with the relevant guidelines and regulations. Consent for publication Not applicable. Competing interests The authors declare no competing interests., (© 2024. The Author(s).)