A team of researchers has performed the most comprehensive coordinated comparison of optical clocks - a type of high-precision atomic clock - to date, running them simultaneously in six different countries. According to the authors, who publish the results in the journal Optica, the work “supports progress toward a redefinition of the second” and could serve to “develop entirely new applications and advance scientific projects that depend on time and frequency.”

A model has analysed mercury concentrations in rivers around the world from 1850 to the present day. The results, published in Science Advances, conclude that levels have doubled and even tripled since the Industrial Revolution: before 1850, rivers carried approximately 390 metric tonnes of mercury to the oceans each year, and today that figure has risen to around 1,000 metric tonnes. According to the authors, these results have implications for human health and wildlife, as mercury compounds are neurotoxic, can accumulate in fish and pose a health risk through consumption.

A study evaluating the mathematical and linguistic performance of first- and second-year primary school students in France—more than 2.6 million children between 2018 and 2022—shows that the gender gap in mathematics appears within a few months of starting primary school. This gap increases with years of schooling, not with age, adds the research published in Nature.

Menstrual cycle tracking apps pose risks to users, according to a report published by the Minderoo Centre for Technology and Democracy at the University of Cambridge (United Kingdom). These apps collect intimate data about their users' physical and mental health and reproductive decisions, which can be exploited for commercial or legal purposes, the report warns.

An oral formulation of risperidone could be administered weekly instead of daily to treat patients with schizophrenia with the same efficacy, according to a phase III clinical trial published in The Lancet Psychiatry. The study included 83 patients in the United States.

A team from the United States has analysed data on modes of transport in more than 11,500 cities in 121 countries around the world, including Spain, representing 41% of the world's population. In addition to studying the factors that most influence the proportion of journeys made on foot or by bicycle, they estimate that if each city analysed increased the extent of its cycling network to the level of Copenhagen (Denmark), private vehicle emissions would be reduced by 6% and the public health benefits would be equivalent to around £37 billion. The results are published in the journal PNAS.

An international study has warned of the potential risks of widespread use of faecal microbiota transplantation without taking into account the region of the intestine where the transferred microbes arrive. The experiment, conducted on mice and human tissue samples, showed that the microbes from the transplant—mostly anaerobic microbes from the colon—colonised the small intestine, persisted there for months and modified that new environment, causing changes in the host's metabolism. According to the authors, whose study is published in the journal Cell, this may have long-lasting and unforeseen consequences, as well as imbalances in the intestinal ecosystem of patients.

Several studies have suggested that taurine concentrations in the blood decrease with age and that supplementation with this amino acid could delay ageing. Now, a study carried out in the USA with Spanish participation, including data from humans, monkeys and mice, shows that this decline is not systematic and that it depends more on individual factors than on ageing, so taurine is not a reliable marker of ageing. The results are published in the journal Science.

So-called precision oncology involves the use of drugs that target specific molecular alterations in the tumour. These therapies are usually tested in clinical trials in adults and most have not been approved for use in children. An opinion article calls for these trials to be extended to children as well, given the difficulty of conducting such trials in children due to the small number of cases. According to the authors, who publish the text in the journal Trends in Cancer, given that children and adolescents tend to tolerate therapy better than older adults, ‘the time has come to consider age-agnostic approvals, i.e. approvals that include children and adults of any age’.

Children will suffer more from the climate crisis than their grandparents. Fifty-two per cent of people born in 2020 will experience unprecedented heat waves throughout their lives, compared to 16 per cent of those born in 1960. This was calculated by a study published in Nature last month, assuming that temperatures rise 1.5 °C above pre-industrial levels. In this article, we analyse the profile of children who already suffer from heat in our country and explain how to adapt their environments to extreme temperatures.