Efeitos da exposição a radiação eletromagnética na função testicular e reprodutiva

A infertilidade constitui um problema grave na sociedade moderna, e o aumento da sua prevalência surge da interação complexa entre um conjunto de fatores sociais, comportamentais e biológicos. Um em cada 6 casais tem dificuldades em conceber uma gestação, e em cerca de 50% dos casais afetados o fator masculino constitui agente causal, quer primário quer associado a condições femininas. Considerando a fertilidade masculina, é um facto que a incidência de espermatogénese irregular está a aumentar devido a fatores ambientais e relacionados com o estilo de vida. De entre estes fatores, destaca-se o crescente uso de telemóveis, cujo número de utilizadores continua a aumentar a nível global. O aumento exponencial na utilização de telemóveis é acompanhado por uma preocupação crescente em relação aos seus possíveis efeitos prejudiciais na saúde humana. Vários autores defendem que a radiação eletromagnética emitida pelos telemóveis, e respetivas antenas, pode prejudicar a fertilidade. O sistema reprodutor masculino é altamente complexo e sensível a fatores intrínsecos e extrínsecos, e a radiação eletromagnética emitida pelos telemóveis pode ter efeitos nefastos na espermatogénese, reduzindo a fertilidade masculina. O objetivo da presente tese é realizar uma revisão sistemática da literatura sobre os mecanismos fisiopatológicos envolvidos nos efeitos das radiações eletromagnéticas emitidas pelos telemóveis na estrutura e função testicular, através da análise de estudos realizados em modelos humanos e animais. Nos estudos em humanos baseados na comparação dos parâmetros do esperma entre homens que usam telemóvel e homens que não usam, destacaram-se a redução na mobilidade (principalmente nos espermatozoides rapidamente progressivos), e a alteração da morfologia. Nos estudos em humanos assentes na confrontação dos parâmetros do esperma entre amostras expostas às radiações eletromagnéticas dos telemóveis e amostras de controlo, ambas provenientes do mesmo indivíduo, evidenciaram-se a diminuição na mobilidade, a quebra na viabilidade e o aumento na produção de espécies reativas de oxigénio. Nos estudos em animais sobressaíram a diminuição da mobilidade, o decréscimo na concentração do esperma e o incremento na geração de espécies reativas de oxigénio. No cômputo dos estudos em modelos humanos e modelos animais, destaca-se a mobilidade dos espermatozoides, que constituiu a característica negativamente afetada de forma mais consistente pelas radiações eletromagnéticas dos telemóveis. Mais estudos devem ser realizados, e estes devem reunir entre si uma maior homogeneidade, de forma que os dados obtidos sejam mais consistentes e fiáveis, no intuito de revelar a real influência das radiações eletromagnéticas dos telemóveis na fertilidade masculina.Infertility is a serious problem in modern society, and the increase in its prevalence arises from the complex interaction between a range of social, behavioral and biological factors. One in six couples has difficulty to conceive, and in about 50% of affected couples the male factor is the causal agent, either primary or associated with female conditions. Considering male fertility, it is a fact that the incidence of irregular spermatogenesis is increasing due to environmental and lifestyle related factors. Among these factors stands out the growing use of mobile phones whose number of users continues to increase globally. The exponential increase in mobile phone use is accompanied by a growing concern over its possible adverse effects on human health. Several authors argue that electromagnetic radiation emitted by mobile phones and their antennas, can impair fertility. The male reproductive system is highly complex and sensitive to intrinsic and extrinsic factors, and electromagnetic radiation emitted by mobile phones can have deleterious effects on spermatogenesis, reducing male fertility. The aim of this study is to conduct a systematic literature review on the pathophysiological mechanisms involved in the effects of electromagnetic radiation emitted by mobile phones in testicular structure and function, through analysis of studies in human and animal models. In human studies based on a comparison of sperm parameters between men that use mobile phone and men who do not use, the main alterations were the decreased mobility (especially in rapidly progressive spermatozoa) and the altered morphology. In human studies based on a comparison of sperm parameters between sperm samples exposed to electromagnetic radiation from mobile phones and control samples, both from the same individual, the main alterations were the decreased mobility, the declined viability and the increased production of reactive oxygen species. In animal studies the main alterations were the decreased mobility, the decreased sperm concentration and the increased generation of reactive oxygen species. Considering all human and animal studies, sperm mobility was the most consistently affected parameter by the mobile phone electromagnetic radiation. More studies are needed, and these should be more homogeneous to obtained more consistent and reliable data, in order to reveal the real influence of mobile phone electromagnetic radiation on male fertility

Pervasive gaps in Amazonian ecological research

Biodiversity loss is one of the main challenges of our time,1,2 and attempts to address it require a clear un derstanding of how ecological communities respond to environmental change across time and space.3,4 While the increasing availability of global databases on ecological communities has advanced our knowledge of biodiversity sensitivity to environmental changes,5–7 vast areas of the tropics remain understudied.8–11 In the American tropics, Amazonia stands out as the world’s most diverse rainforest and the primary source of Neotropical biodiversity,12 but it remains among the least known forests in America and is often underrepre sented in biodiversity databases.13–15 To worsen this situation, human-induced modifications16,17 may elim inate pieces of the Amazon’s biodiversity puzzle before we can use them to understand how ecological com munities are responding. To increase generalization and applicability of biodiversity knowledge,18,19 it is thus crucial to reduce biases in ecological research, particularly in regions projected to face the most pronounced environmental changes. We integrate ecological community metadata of 7,694 sampling sites for multiple or ganism groups in a machine learning model framework to map the research probability across the Brazilian Amazonia, while identifying the region’s vulnerability to environmental change. 15%–18% of the most ne glected areas in ecological research are expected to experience severe climate or land use changes by 2050. This means that unless we take immediate action, we will not be able to establish their current status, much less monitor how it is changing and what is being lostinfo:eu-repo/semantics/publishedVersio

A search for ultra-high-energy photons at the Pierre Auger Observatory exploiting air-shower universality

The Pierre Auger Observatory is the most sensitive detector to primary photons with energies above ∼0.2 EeV. It measures extensive air showers using a hybrid technique that combines a fluorescence detector (FD) with a ground array of particle detectors (SD). The signatures of a photon-induced air shower are a larger atmospheric depth at the shower maximum (X$_{max}$) and a steeper lateral distribution function, along with a lower number of muons with respect to the bulk of hadron-induced background. Using observables measured by the FD and SD, three photon searches in different energy bands are performed. In particular, between threshold energies of 1-10 EeV, a new analysis technique has been developed by combining the FD-based measurement of X$_{max}$ with the SD signal through a parameter related to its muon content, derived from the universality of the air showers. This technique has led to a better photon/hadron separation and, consequently, to a higher search sensitivity, resulting in a tighter upper limit than before. The outcome of this new analysis is presented here, along with previous results in the energy ranges below 1 EeV and above 10 EeV. From the data collected by the Pierre Auger Observatory in about 15 years of operation, the most stringent constraints on the fraction of photons in the cosmic flux are set over almost three decades in energy

Study on multi-ELVES in the Pierre Auger Observatory

Since 2013, the four sites of the Fluorescence Detector (FD) of the Pierre Auger Observatory record ELVES with a dedicated trigger. These UV light emissions are correlated to distant lightning strikes. The length of recorded traces has been increased from 100 μs (2013), to 300 μs (2014-16), to 900 μs (2017-present), to progressively extend the observation of the light emission towards the vertical of the causative lightning and beyond. A large fraction of the observed events shows double ELVES within the time window, and, in some cases, even more complex structures are observed. The nature of the multi-ELVES is not completely understood but may be related to the different types of lightning in which they are originated. For example, it is known that Narrow Bipolar Events can produce double ELVES, and Energetic In-cloud Pulses, occurring between the main negative and upper positive charge layer of clouds, can induce double and even quadruple ELVES in the ionosphere. This report shows the seasonal and daily dependence of the time gap, amplitude ratio, and correlation between the pulse widths of the peaks in a sample of 1000+ multi-ELVES events recorded during the period 2014-20. The events have been compared with data from other satellite and ground-based sensing devices to study the correlation of their properties with lightning observables such as altitude and polarity

Studies of the mass composition of cosmic rays and proton-proton interaction cross-sections at ultra-high energies with the Pierre Auger Observatory

In this work, we present an estimate of the cosmic-ray mass composition from the distributions of the depth of the shower maximum (Xmax) measured by the fluorescence detector of the Pierre Auger Observatory. We discuss the sensitivity of the mass composition measurements to the uncertainties in the properties of the hadronic interactions, particularly in the predictions of the particle interaction cross-sections. For this purpose, we adjust the fractions of cosmic-ray mass groups to fit the data with Xmax distributions from air shower simulations. We modify the proton-proton cross-sections at ultra-high energies, and the corresponding air shower simulations with rescaled nucleus-air cross-sections are obtained via Glauber theory. We compare the energy-dependent composition of ultra-high-energy cosmic rays obtained for the different extrapolations of the proton-proton cross-sections from low-energy accelerator data

Study of downward Terrestrial Gamma-ray Flashes with the surface detector of the Pierre Auger Observatory

The surface detector (SD) of the Pierre Auger Observatory, consisting of 1660 water-Cherenkov detectors (WCDs), covers 3000 km2 in the Argentinian pampa. Thanks to the high efficiency of WCDs in detecting gamma rays, it represents a unique instrument for studying downward Terrestrial Gamma-ray Flashes (TGFs) over a large area. Peculiar events, likely related to downward TGFs, were detected at the Auger Observatory. Their experimental signature and time evolution are very different from those of a shower produced by an ultrahigh-energy cosmic ray. They happen in coincidence with low thunderclouds and lightning, and their large deposited energy at the ground is compatible with that of a standard downward TGF with the source a few kilometers above the ground. A new trigger algorithm to increase the TGF-like event statistics was installed in the whole array. The study of the performance of the new trigger system during the lightning season is ongoing and will provide a handle to develop improved algorithms to implement in the Auger upgraded electronic boards. The available data sample, even if small, can give important clues about the TGF production models, in particular, the shape of WCD signals. Moreover, the SD allows us to observe more than one point in the TGF beam, providing information on the emission angle

Combined fit to the spectrum and composition data measured by the Pierre Auger Observatory including magnetic horizon effects

The measurements by the Pierre Auger Observatory of the energy spectrum and mass composition of cosmic rays can be interpreted assuming the presence of two extragalactic source populations, one dominating the flux at energies above a few EeV and the other below. To fit the data ignoring magnetic field effects, the high-energy population needs to accelerate a mixture of nuclei with very hard spectra, at odds with the approximate E$^{-2}$ shape expected from diffusive shock acceleration. The presence of turbulent extragalactic magnetic fields in the region between the closest sources and the Earth can significantly modify the observed CR spectrum with respect to that emitted by the sources, reducing the flux of low-rigidity particles that reach the Earth. We here take into account this magnetic horizon effect in the combined fit of the spectrum and shower depth distributions, exploring the possibility that a spectrum for the high-energy population sources with a shape closer to E$^{-2}$ be able to explain the observations