Conectar
by Carmen Villagrasa, Giorgio Baiocco, Zine-El-Abidine Chaoui, Michael Dingfelder, Sébastien Incerti, Pavel Kundrát, Ioanna Kyriakou, Yusuke Matsuya, Takeshi Kai, Alessio Parisi, Yann Perrot, Marcin Pietrzak, Jan Schuemann, Hans Rabus
Biological effects induced by diverse types of ionizing radiation are known to show important variations. Nanodosimetry is suitable for studying the link between these variations and the patterns of radiation interactions within nanometer-scale volumes, using experimental techniques complemented by Monte Carlo track structure (MCTS) simulations. However, predicted nanodosimetric quantities differ among MCTS codes, primarily because each code employs distinct molecular-scale particle interaction models. This multi-code study examines these variations for low-energy electrons (20–10,000 eV), which play a critical role in energy deposition and biological effects by virtually all types of ionizing radiation. Specifically, the hypothesis tested in this work is that inter-code variability in nanodosimetry results is mainly caused by differences in assumptions regarding total interaction cross sections. Ionization cluster size distributions and derived nanodosimetric parameters were simulated with seven MCTS codes (PARTRAC, PHITS-TS, MCwater, PTra, and three Geant4-DNA options) in liquid water as a surrogate for biological tissue. Significant inter-code differences were observed, especially at the lowest energies. They were substantially reduced upon replacing the original cross sections in each code with a common, averaged dataset, created ad-hoc for this study and not based on theoretical assumptions. For example, for 50 eV electrons in 8 nm spheres, the variability in the predicted mean ionization numbers decreased from 23% to 5%, and in the probability of inducing two or more ionizations from 34% to 7% (relative standard deviations). This quantification demonstrates that total interaction cross sections are the primary source of uncertainty at low electron energies. A sensitivity test using DNA damage simulations with the PARTRAC code revealed that cross section variations notably affect biological outcome predictions. Replacing the code’s original cross sections with the averaged ones increased the predicted double-strand break yield by up to 15%. These findings underscore the urgent need for improved characterization of low-energy electron interaction cross sections to reduce uncertainties in MCTS simulations and enhance mechanistic understanding of radiation-induced biological effects.
by Frederick Nchang Cho, Marie Clarie Fien Ndim, Diane Zinkeng Tongwa, Christabel Afor Tatah, Franklin Ngwesse Ngome, Eugine Mbuh Nyanjoh, Andrew N Tassang
BackgroundHuman Immunodeficiency Virus (HIV) remains a major public health concern in sub-Saharan Africa. In Cameroon, young people are disproportionately affected but underrepresented in HIV testing statistics.
ObjectiveTo explore knowledge, attitudes, and behaviours related to HIV testing among youth in Kumba, Cameroon, and to identify barriers to inform community-based interventions.
MethodsA cross-sectional qualitative study was conducted using nine focus group discussions (FGDs) with 75 youth (52 females and 23 males) aged 18 - 35 years across four quarters in the Kumba II municipality. Participants were purposively sampled to reflect diverse educational and occupational backgrounds. Data were thematically analysed using Braun and Clarke’s framework with NVivo Version 14.
ResultsParticipants demonstrated high awareness of HIV testing services (90.7%) and transmission via sexual contact (96.0%), though knowledge gaps remained regarding non-sexual transmission and testing procedures. While 93.3% had previously undergone HIV testing, 57.3% reported stigma and 46.7% raised confidentiality concerns as ongoing barriers. Female participants feared being labelled as promiscuous, while males cited social norms that discourage help-seeking. Most participants supported school-based or youth-centred community testing, emphasising the need for privacy and youth-friendly environments. Key motivators for testing included the desire to know one’s status (82.7%), symptom appearance (28.0%), and unprotected sex (17.3%).
ConclusionsDespite strong awareness and high testing uptake, stigma and confidentiality concerns persist among youth in Kumba. To enhance HIV testing rates, community-based strategies should prioritise mobile clinics, peer outreach, and confidential youth-centred services. Strengthening education about HIV transmission and demystifying the testing process may further reduce barriers.
by Ariene Silva do Carmo, Paulo César Pereira de Castro Júnior, Thais Cristina Marquezine Caldeira, Daniela Silva Canella, Rafael Moreira Claro, Luiza Delazari Borges, Larissa Loures Mendes
The present study analyzed the prices of food sold in canteens of Brazilian private schools and described price-based marketing strategies, according to the NOVA food classification system. This is a mixed methods study combining a cross-sectional component and time series analysis, with data from 2,241 canteens in private elementary and secondary schools in the 26 capitals of Brazil and the Federal District, collected between June 2022 and June 2024. Price data collected for unprocessed, minimally processed, or processed foods and culinary preparations based on these foods (UMPCP), and ultra-processed foods and culinary preparations based on these foods (UpCP) sold in school canteens and from the National System of Consumer Price Indices (SNIPC), were used to create a data set containing deflated monthly prices for food and beverages sold between August 2022 and July 2024. Calculations were made for adjusted prices (R$/100 g or ml) and absolute prices (R$ per portion), and frequency of use of strategies such as combos and promotions. UMPCP showed lower adjusted price, but higher absolute price than UpCP, especially for solid foods. About 27% of the study canteens implemented pricing strategies for both food groups. Most of these strategies did not exclusively favor healthy foods, indicating that promotions and combos were used without distinction. The affordability of healthy foods is disadvantaged in school canteens when considering the price per portion, which may negatively influence students’ food choices. The findings show that current prices for food sold in most canteens discourage the purchase of healthy items, but favor the purchase of unhealthy ones. These results reinforce the importance of interventions for promoting healthy foods and making them more affordable.
by Susanne Jordan, Sarah Jane Böttger, Sabine Zinn
Health information about vaccinations is communicated via various sources of information and is crucial for vaccination decisions. Information sources such as interpersonal sources, traditional print and digital media as well as social media offer information about the risks and benefits of vaccination. During health crises such as the COVID-19 pandemic was, some information sources provide hanging or contradictory information, alongside with misinformation and disinformation. Little is known about the relationship between the reported persuasiveness of different sources of information for individual vaccination decisions and differences in this between the vaccinated and unvaccinated. Utilizing data from 10,284 participants in the “Corona-Monitoring Nationwide” survey in Germany from winter 2021/22, this study explored the relationship between the persuasiveness of information sources and vaccination decisions, considering socio-demographic and pandemic-related factors. For more than half of respondents, talks with family, friends, and acquaintances were the most convincing. Traditional media like television and radio were reported by 44%. Newspapers/magazines (online or print) and talks with physicians were each found the most convincing by around one third. About one fifth were persuaded by public authority’s flyers or websites. Less than a tenth each was convinced by social media/messenger services, brochures from pharmacies and health insurances, talks with pharmacy staff or online health portals. Significant differences emerged between vaccinated and unvaccinated individuals. Unvaccinated people were four times more likely to report social media and messenger services as convincing compared to vaccinated people. Reporting talks with doctors and flyers/websites from public authorities as very persuasive significantly reduced the likelihood of being unvaccinated. The findings suggest that in future health crises, information should be disseminated through diverse sources, using both traditional and digital media, as well as interpersonal communication. Proactive science communication on social media and messenger services is crucial to counteract misinformation and disinformation.
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