Isotope geochemistry and petrogenesis of peralkaline Middle Miocene ignimbrites from central Sonora: relationship with continental break-up and the birth of the Gulf of California

Middle Miocene peralkaline ignimbrites constitute a specific geodynamic marker of the early stage of opening of the Gulf of California, preserved either in central Sonora or the Puertecitos area, in Baja California. Very uniform ages (12-12.5 Ma) obtained on these rocks show that this volcanic episode corresponds to a specific stage in the tectonic evolution of the proto-gulf area. Field observations and slightly different Sr and Nd isotopic signatures support eruptions from several small volume magma batches rather than from a large-volume caldera forming event. Isotopic ratios help to constrain the petrogenesis of the peralkaline liquids by fractional crystallization of transitional basalts in a shallow reservoir, with slight contamination by Precambrian upper crustal material. Less differentiated glomeroporphyritic icelandites erupted at about 11 Ma, mark an increase in the magma production rate and highlight an easier access to the surface, illustrating an advanced stage in the weakening of the continental crust. The tilting of the Middle Tertiary sequences results from a major change in the tectonic regime, from E-W extension giving rise to N-S grabens, to NNW-SSE strike-slip motion that can be related to the transfer of Baja California from North America to the Pacific plate. The location of peralkaline volcanism coincides with the southern edge of the Precambrian crust and the southernmost extension of the California slab window at 12.5 Ma

(Quantum) Space-Time as a Statistical Geometry of Fuzzy Lumps and the Connection with Random Metric Spaces

We develop a kind of pregeometry consisting of a web of overlapping fuzzy lumps which interact with each other. The individual lumps are understood as certain closely entangled subgraphs (cliques) in a dynamically evolving network which, in a certain approximation, can be visualized as a time-dependent random graph. This strand of ideas is merged with another one, deriving from ideas, developed some time ago by Menger et al, that is, the concept of probabilistic- or random metric spaces, representing a natural extension of the metrical continuum into a more microscopic regime. It is our general goal to find a better adapted geometric environment for the description of microphysics. In this sense one may it also view as a dynamical randomisation of the causal-set framework developed by e.g. Sorkin et al. In doing this we incorporate, as a perhaps new aspect, various concepts from fuzzy set theory.Comment: 25 pages, Latex, no figures, some references added, some minor changes added relating to previous wor

Use of mixed methods designs in substance research: a methodological necessity in Nigeria

The utility of mixed methods (qualitative and quantitative) is becoming increasingly accepted in health sciences, but substance studies are yet to substantially benefit from such utilities. While there is a growing number of mixed methods alcohol articles concerning developed countries, developing nations are yet to embrace this method. In the Nigerian context, the importance of mixed methods research is yet to be acknowledged. This article therefore, draws on alcohol studies to argue that mixed methods designs will better equip scholars to understand, explore, describe and explain why alcohol consumption and its related problems are increasing in Nigeria. It argues that as motives for consuming alcohol in contemporary Nigeria are multiple, complex and evolving, mixed method approaches that provide multiple pathways for proffering solutions to problems should be embraced

Persistence of Gamma-H2AX Foci in Irradiated Bronchial Cells Correlates with Susceptibility to Radiation Associated Lung Cancer in Mice

The risk of developing radiation-induced lung cancer differs between different strains of mice, but the underlying cause of the strain differences is unknown. Strains of mice also differ in their ability to efficiently repair DNA double strand breaks resulting from radiation exposure. We phenotyped mouse strains from the CcS/Dem recombinant congenic strain set for their efficacy in repairing DNA double strand breaks during protracted radiation exposures. We monitored persistent gamma-H2AX radiation induced foci (RIF) 24 hours after exposure to chronic gamma-rays as a surrogate marker for repair deficiency in bronchial epithelial cells for 17 of the CcS/Dem strains and the BALB/cHeN founder strain. We observed a very strong correlation R2 = 79.18%, P < 0.001) between the level of persistent RIF and radiogenic lung cancer percent incidence measured in the same strains. Interestingly, spontaneous levels of foci in non-irradiated strains also showed good correlation with lung cancer incidence (R2=32.74%, P =0.013). These results suggest that genetic differences in DNA repair capacity largely account for differing susceptibilities to radiation-induced lung cancer among CcS/Dem mouse strains and that high levels of spontaneous DNA damage is also a relatively good marker of cancer predisposition. In a smaller pilot study, we found that the repair capacity measured in peripheral blood leucocytes also correlated well with radiogenic lung cancer susceptibility, raising the possibility that such phenotyping assay could be used to detect radiogenic lung cancer susceptibility in humans

The defect in the AT-like hamster cell mutants is complemented by mouse chromosome 9 but not by any of the human chromosomes

X-ray-sensitive Chinese hamster V79 cells mutants, V-C4, V-E5 and V-G8, show an abnormal response to X-ray-induced DNA damage. Like ataxia telangiectasia (AT) cells, they display increased cell killing, chromosomal instability and a diminished inhibition of DNA synthesis following ionizing radiation. To localize the defective hamster gene (XRCC8) on the human genome, human chromosomes were introduced into the AT-like hamster mutants, by microcell mediated chromosome transfer. Although, none of the human chromosomes corrected the defect in these mutants, the defect was corrected by a single mouse chromosome, derived from the A9 microcell donor cell line. In four independent X-ray-resistant microcell hybrid clones of V-E5, the presence of the mouse chromosome was determined by fluorescent in situ hybridization, using a mouse cot-1 probe. By PCR analysis with primers specific for different mouse chromosomes and Southern blot analysis with the mouse Ldlr probe, the mouse chromosome 9, was identified in all four X-ray-resistant hybrid clones. Segregation of the mouse chromosome 9 from these hamster-mouse microcell hybrids led to the loss of the regained X-ray-resistance, confirming that mouse chromosome 9 is responsible for complementation of the defect in V-E5 cells. The assignment of the mouse homolog of the ATM gene to mouse chromosome 9, and the presence of this mouse chromosome only in the radioresistant hamster cell hybrids suggest that the hamster AT-like mutants are homologous to AT, although they are not complemented by human chromosome 11

Sexual health knowledge and behaviours in International MSM Students in Australia

Background International sexual minority students, particularly men who have sex with men (MSM), experience disparities in health, including a significantly higher prevalence of HIV and other STIs and lower levels of sexual health services use. Limited research has been conducted in this population around sexual health knowledge, behaviour and services use. Methods A multi-language cross-sectional online survey was completed by 168 international MSM tertiary students (median age: 25 years) in New South Wales (Australia). Variables included demographics, sexual identity and behaviour, sexual health knowledge and behaviour including PrEP use as well as sexual health services use. Descriptive and correlational analyses, and binary logistic regressions were conducted. Results Sexual health knowledge including routes of HIV transmission was overall high in the sample, while 20% had limited knowledge regarding pre-exposure prophylaxis (PrEP) and 28% regarding post-exposure prophylaxis (PEP). Less than half (44%) reported inconsistent condom use. PrEP use was low in the sample (14%) and not correlated with condom use. Sexual health behaviours and dimensions LGBT Community connectedness were significantly correlated with the use of different sexual health services. Conclusions This first comprehensive study among international MSM tertiary students in Australia demonstrates a high level of inconsistent condom use and low levels of PrEP use as well as strong correlations between sexual health behaviour and HIV/STI testing, and connectedness with other sexual minority men. International MSM students do not feel included in the local LGBT Community but demonstrate a strong desire to be involved. Those included were more likely to use vital sexual health services. Main Message International MSM students are an emerging priority population for sexual health research and practice. , and future health promotion campaigns should consider incorporating strong community building and connectedness elements

Perceptions and willingness concerning the collection of sexual orientation and gender identity data in Australian healthcare services

Background Despite growing recognition of the importance of collecting sexual orientation and gender identity (SOGI) data to improve healthcare access and equity for LGBTQA+ populations, uncertainty remains around how these data are collected, their perceived importance and individuals' willingness to disclose such information in healthcare settings. The aim of this study was to understand perceptions of the collection of data on sexual orientation and gender identity in healthcare settings across Australia, and individuals' willingness to provide this data. Methods A cross-sectional online survey of 657 Australian residents was conducted to assess participants' attitudes towards SOGI data in healthcare settings, along with preferences for methods to collect these data. Statistical analyses included ANCOVA, Chi-squared tests and Wilcoxon signed-rank tests. Results Participants generally recognised the importance of the collection of basic demographic data to support the provision of health services. Willingness to share SOGI data varied, with significant differences noted across gender, sexual orientation and cultural backgrounds. LGBTQA+ participants expressed greater willingness to provide SOGI data, but only in contextually appropriate situations, and preferred more inclusive data collection methods. Conclusions The study shows a context-dependent willingness to provide SOGI data in health care, underscoring the need for sensitive data collection methods. Insights into SOGI data collection attitudes are vital for developing inclusive and respectful healthcare practices. Improved SOGI data collection can enrich healthcare outcomes for diverse groups, informing public health policies and practices tailored to LGBTQA+ needs