University of Valencia

A "large fraction" of groundwater samples are contaminated by perfluoroalkyl and polyfluoroalkyl substances (PFASs) and would be considered unacceptable for drinking water, a study claims. The analysis, published by Nature Geoscience, brings together data from 273 studies of surface and groundwater samples from around the world since 2004. The exact proportion of samples exceeding the thresholds varies according to the standards considered. For example, 69% of groundwater samples with no known source of contamination exceed the Canadian threshold, but the figure is only 6% if the EU criterion for the sum of all PFASs is considered.

A meta-analysis by the University of Valencia has studied the links between leisure reading habits on digital devices and the reading comprehension of students of different ages. The research - which is based on 25 studies published between 2000 and 2022 involving some 470,000 students from different countries - concludes that in the early stages (primary and 1st and 2nd ESO in the Spanish case) there were small negative relationships between digital leisure reading and reading comprehension, while in later stages (3rd and 4th ESO, baccalaureate and university) the relationship became slightly positive. The research is published in Review of Educational Research.

A team of researchers has managed to combine more than seven synthetic chromosomes made in the laboratory in a single yeast cell. This involves developing for the first time a eukaryotic cell with more than 50% synthetic DNA, which survives and replicates in a similar way to wild yeast strains. The results, which are part of the Synthetic Yeast Genome Project (Sc2.0), are published in the journal Cell.

The vast majority of mammals remain fertile until the end of their lives. Humans and some species of whales deviate from that norm and do go through menopause. Now, research published in Science reveals that menopause exists in female chimpanzees, too, and that it lasts for a fifth of their adult lifespan. To reach these conclusions, the research team observed 185 female chimpanzees between 1995 and 2016 in Uganda's Kibale National Park and measured hormone levels in urine samples from specimens of various ages.

When considering which type of timetable is best, one question is: best for what and for whom? Not only does the scientific evidence on student learning and well-being come into play, but also the employment interests of teachers, the reconciliation needs of families, and the effects of each type of timetable on socio-economic inequality and the gender gap in care are also involved. We bring together more elements of the discussion in this second article.

Every school year in Spain, the debate returns about what kind of timetable schools should adopt: is it better to concentrate all teaching hours or to have a lunch break and extend the time spent at school? In this first issue, we bring together research on the effect of each type of timetable on students' performance, rest and socio-affective well-being, as well as the available data on public and charter education.

The International Pulsar Timing Array (IPTA) consortium has discovered evidence for the existence of a cosmic background of gravitational waves. The results, published by different IPTA consortia in several scientific journals, would show that this cosmic background would be the result of collisions of supermassive black holes. In 2015, researchers from the LIGO and Virgo collaborations made the first direct observation of gravitational waves caused by the collision of two stellar-mass black holes. These waves oscillate several times per second. What the consortia have now found are gravitational waves emitted by supermassive binary black holes at the centre of galaxies, waves that oscillate on timescales of many years.

From May to August 2022, 157,580 deaths were recorded, 20.5% more than in the same months of 2019, before covid. This increase in mortality was mainly among people aged 75 years and older. Of the causes of death directly related to the heat, heat stroke and dehydration stood out. These are some of the provisional data published by the National Statistics Institute (INE) in relation to deaths in 2022. Covid-19 was the most frequent cause of death, with 31,559 people dying, 20% less than in 2021.

The World Health Organisation (WHO) Emergency Committee met on 4 May to assess whether covid-19 could continue to be considered a health emergency of international concern (PHEIC). The organisation's director general, Tedros Adhanom, has followed its recommendation and ended the emergency declared on 30 January 2020. "It is with great hope that I declare that covid-19 has ended as a global health emergency. However, this does not mean that covid-19 is no longer a threat to global health. Last week, it claimed one life every three minutes, and that's just the deaths we know about," he told a press conference.

More than two thirds of Spanish citizens think that artificial intelligence presents a very high or high risk that we will be manipulated with our data by companies or governments. However, just over a third believe that artificial intelligence will have an impact on improving the quality of public services and companies. These are some of the results gathered in the 2022 edition of the Survey of Social Perception of Science and Technology published today by the Spanish Foundation for Science and Technology (FECYT), carried out among more than 6,000 people with face-to-face interviews in the 17 autonomous communities.