Latest news with #RuhrUniversityBochum
Forbes
23-07-2025
- Science
- Forbes
Street Lamps Aren't The Main Source Of Light Pollution In Cities
Light pollution is a growing issue for our cities, and Hong Kong is no exception (photo taken on ... More Friday, July 4, 2025) How dark is the night sky where you live? If you're in an urban area, the answer will likely be 'not dark at all'. The pervasiveness of artificial light – be it in the form of streetlamps, billboards, screens or floodlights – keeps our cities bright long after most people have gone to bed. And it's on the rise. In 2016, a group of researchers found that 83% of the world's population and more than 99% of people in the U.S. and Europe live under light-polluted skies. In 2023, some of the same authors showed that the average night sky is getting brighter by 9.6% per year, due to artificial light in our surroundings spilling into the atmosphere. This is equivalent to a quadrupling of sky brightness over the duration of a human childhood (18 years). And while it's true that almost all light pollution is generated in urban areas, its effects extend beyond the streetscape. The 'light domes' of Las Vegas and Los Angeles can be seen from Death Valley National Park, despite it being 150km and 250km away, respectively. For many city-dwellers, true outdoor darkness is not something they experience regularly. In discussions around light pollution, the switch to LED (light-emitting diodes) streetlamps is often mentioned as a contributing factor. The high efficiency and low cost of LEDs makes them increasingly common on our urban roads. But if its pollution we're interested in, then it's not the streetlamps we should be talking about. The Nachtlichter ('night lights' in German) campaign involved hundreds of citizen scientists ... More counting and classifying many thousands of light sources in urban areas. They found that streetlamps make up a relatively small fraction of the total Bright lights, big city In Germany in 2021, a group of 257 citizen scientists, led by Dr Christopher Kyba (Ruhr University Bochum), carried out a novel study on artificial light at night (ALAN). Using a dedicated app called Nachtlichter ('night lights' in German), they counted and classified 234,044 illuminated light sources across a 22-km2 area that included city centers, residential neighborhoods, commercial and industrial areas. No areas with skyscrapers were included in the survey. Their findings, published last week in the journal Nature Cities, showed that public streetlamps make up a relatively small percentage (10-13%) of all contaminating light sources counted. In dense areas, streetlamps were outnumbered by other light sources by a factor of up to 7. Instead, they found that private windows were by far the most frequently observed light source, representing more than 48% of the total. Commercial windows were the third most common type of night-time light source (7.4%), with floodlights and other building-mounted lights following closely behind (7.3% of the total). Signs – both illuminated and self-luminous – represented 5.5% of the total count. In terms of the brightness of surveyed lights, the vast majority of streetlamps were shieled, meaning that the light was being directed towards the ground, rather than 'trespassing' into the atmosphere. In contrast, the majority (58%) of observed floodlights and 29% of building-mounted lights were unshielded, and so were casting their light upwards, adding to the overall light pollution. The team's study area was chosen specifically to overlap with the path of a passing satellite carrying an instrument called the Visible Infrared Imaging Radiometer Suite (VIIRS). VIIRS is ultra-sensitive in low-light conditions, and is regularly used to monitor night-time lights from space. This allowed the Nachtlichter team to make a comparison between their ground-based lighting inventory, and the orbit-based measurements of the same area. 'By comparing these data with the satellite observations, we identified a correlation between the number of counted lights per square kilometer and the radiance observed by the satellite sensor,' says Kyba. He continues, 'Both energy and lighting policy as well as research on the effects of artificial light on the environment have generally focused on street lighting. Our findings indicate that a broader approach that considers all lighting is necessary in order to understand and reduce the environmental impacts of light in cities." This photograph taken on March 22, 2025, shows a view of the ancient Acropolis with lights off ... More during the Earth Hour environmental campaign in Athens. Earth Hour is a global call to turn off lights for one hour in a bid to highlight the global climate change. (Photo by ARIS MESSINIS/AFP via Getty Images) Going Dark Another urban sky brightening study published this month focused on Hong Kong; one of the most densely populated regions in the world. There, a group of scientists took advantage of an annual event called Earth Hour to study light pollution. Organized by the World-Wide Fund for Nature (WWF) to raise environmental awareness, Earth Hour involves the voluntary switching off of lights for one hour (20:30-21:30 local time) on a specified day. The campaign is widely supported in Hong Kong, with more than 4,000 organizations and buildings opting in to the 'lights-out' event each year. This provided the team of researchers, led by Dr Chu-Wing So, with an opportunity to directly quantify the impact that bright lights have on the night sky. They examined footage from an all-sky camera installed on the roof of the Hong Kong Space Museum in the Tsim Sha Tsui district, and collected data from a night sky brightness meter co-located with the camera. This allowed them to compare images of the sky before, during, and after the lights-out hour every year from 2015 to 2024. To look at the influence of street-level billboards on storefronts and illuminated signs closer to the ground, they also carried out wide-field photography and a street-level survey. Taken together, this data showed a night sky that was more than 50% darker on average during the lights-out period. They showed that the presence of clouds also amplified the brightening effect of light pollution – as cloud coverage increased from 40% to 85%, urban night sky brightness increased sixfold. To identify the types of lighting that dominate light pollution in this district of Hong Kong, the team set up a portable spectrometer alongside the all-sky camera and brightness meter. This allowed them to identify the specific wavelengths of light that were decreased or absent during the lights-out period. They found that emission reductions mostly occurred in three wavelength bands: 445–500nm, 500-540 nm, and 615–650 nm, which corresponds to blue, green and red emissions from LED billboard screens. They also measured reductions in the 585–595 nm range, which is associated with metal halide floodlights used for facades and billboards. The sodium streetlamps had a negligible impact on sky brightening. They conclude 'the substantial darkening observed in Hong Kong [during Earth Hour] can be largely attributed to the simple act of turning off approximately 120 decorative or advertising lights on commercial buildings and shopping malls. Although they represent only a small fraction of the total external lighting in the city…. they are in fact the main contributors to light pollution in Hong Kong.' The 'light dome' of Los Angeles and other major cities can be visible from great distances. So what? It's becoming increasingly clear that excessive or inappropriate use of artificial lighting at night (ALAN) has widespread implications for ecological health. It can confuse and endanger nocturnal species who are active at night. Migratory birds and bats are diverted and disoriented by the presence of artificial lighting on their routes, with many killed as a result of colliding with brightly-lit structures. Other bird species and frogs change their breeding behaviors. A study published last month looked at 7 years of VIIRS data from 428 cities in Northern Hemisphere concluded that artificial light may be lengthening the growing season in urban environments by as much as 3 weeks compared to rural areas. Humans are also not immune from ALAN's influence, though it can be challenging to separate it out from that of other environmental factors. Unsurprisingly, it has been shown to disrupt our circadian rhythms (the 24-ish hour cycles that regulate how our bodies function, including our wake-sleep cycle). These disruptions, in turn, have been linked to an elevated risk of cardiovascular diseases, chronic stress, disorders and depression. Chronic, long-term, regular, or cumulative exposure to ALAN may even be a risk factor for certain cancers and neurodegenerative diseases. Put simply, too much light at night is bad for everyone. And as these (and many other) studies show, most of the light polluting our night skies has nothing to do with safety on our roads and streets. It's mostly about advertising and poorly mounted floodlights, and to a much lesser extent, people not closing their curtains. The solutions are relatively simple and numerous. As a start: Avoid lighting up places that don't actually need to be lit. Where light is needed, be more intentional about what type, how much, and its location. Use timers or motion sensors to enable lights-out periods. Light pollution is serious. Cities need to start treating it as such.
Yahoo
03-07-2025
- Science
- Yahoo
Scientists Find Most Cats Sleep on Their Left Side – This Could Be Why
Cats sleep between 12 and 16 hours a day, and a new study suggests that most of them prefer to catch these Z's while lying on their left side. Cats are already known to prefer an elevated position when they nap, like the top of a cat tree, or somewhere in the stack of suitcases on your wardrobe, far out of reach from ground predators and cuddle-hungry owners. This behavior allows them to see any threats coming from afar. The study's authors reasoned that cats' sleeping positions – whether they lie on their left or right side – may serve similar functions. "Asymmetries in behavior can have advantages because both hemispheres of the brain specialize in different tasks," says behavioral neuroscientist Onur Güntürkün, from Ruhr University Bochum in Germany. Related: Güntürkün and his team analyzed the sleeping positions of cats in 408 carefully chosen YouTube videos, which revealed a statistically significant leftward bias. Two-thirds of the cats chose to lie on their left, a position that leaves their left visual field unobstructed by their own body. The left visual field feeds into the right brain, which is associated with spatial awareness, threat identification, and the coordination of quick escape. So this sleeping position may grant the cat a quicker reaction time when woken by a predator (or needy human). "Sleep is one of the most vulnerable states for an animal, as anti-predator vigilance is drastically reduced, especially in deep sleeping phases," the study's authors write. "We are inclined to believe that the significant leftward bias in sleeping position in cats may have been evolutionarily driven by hemispheric asymmetries of threat processing, but additional factors cannot be excluded." This research was published in Current Biology. Orcas Caught 'Kissing' For Two Minutes With Tongue Microbe 'Flavors' Tell Octopuses Which Babies Deserve Their Care A Mysterious Blob of Cold Water Defies Ocean Heat – Now We Know Why
Yahoo
02-07-2025
- Health
- Yahoo
Non-alcoholic beer might also be bad for you, scientists find
In something of a dent to the usually healthy image attributed to non-alcoholic beer, researchers have found that such drinks mostly have "an unfavourable metabolic impact" on drinkers, a reason for concern to those trying to manage glucose levels. Following tests in which 44 "young men" drank around a pint of non-alcoholic beer (NAB) a day for a month, the researchers said they observed "metabolic alterations" that sent glucose and fat levels up. The rise in glucose and fat was likely caused by sugar and other "caloric content" in the buzz-free beers, according to the study, published in the journal Nutrients. The team led by Germany's Ruhr-University Bochum and including scientists from the University of California San Diego, St. Louis University and the University of the Basque Country, said they set out to investigate how "daily consumption" of NAB affected "glucose and fat metabolism, body composition and liver function." Of the three categories of booze-free beer studied, pilsener-type drinks were the least bad, the team reported, with wheat-based pints and mixed drinks — the kind with sweeteners or soda blended in — leading to metabolic effects similar to those of fizzy sweet drinks, which have long been a bête noir for health campaigners. Sales of drinks with little or no alcohol have grown in recent years, with the UK, known for its boozy culture, seeing a doubling of sales to almost 1.3 million hectolitres in 2023, going by data put together by drinks industry analysis company IWSR. The study is not the first to undermine the health credentials of booze-free beer, the recent market success of which follows decades of warnings about how alcohol can lead to liver disease and addiction, often with devastating consequences for families of the drinker. In 2023, researchers at Cornell Agritech published proof that zero-alcohol drinks are more susceptible to bacterial contamination than real beer, where the alcohol acts as an "antimicrobial hurdle."
Telegraph
27-06-2025
- Health
- Telegraph
Why cats prefer sleeping on their left side
Cats prefer to sleep on their left side to protect themselves from predators, a study has found. The pets sleep for up to 16 hours a day and often curl up or stretch out for a snooze in opportune places. But the way the animal settles down is not random, and there is an evolutionarily hard-wired logic underpinning it, according to a study from the Ruhr University Bochum in Germany. Scientists found cats lie on their left side around two-thirds of the time, which shows that it was done deliberately. They looked at clips on YouTube of more than 400 sleeping cats and logged which side they were sleeping on. Data revealed that 266 of the cats (66.5 per cent) were on their left side, leaving scientists to conclude this was a survival trait from their history in the wild. Sleeping on their left side means when they wake, their left eye is able to see the local area unobstructed by the cat's own body. This visual information is then processed by the right side of the brain. This hemisphere is what processes threats and is responsible for escaping danger as well as knowing an individual animal's position. This puts the cat at an advantage compared to if it was to sleep on its right side – when the information is processed by the left side of the brain, which is less specialised to aid a swift escape. Anti-predator vigilance This leftward preference is just one of the many ways in which cats protect themselves. 'Sleep is one of the most vulnerable states for an animal, as anti-predator vigilance is drastically reduced, especially in deep sleeping phases,' according to the study. 'Domestic cats are both predators and prey (e.g. for coyotes) and sleep an average of 12–16 hours a day. 'Therefore, they spend almost 60-65% of their lifetime in a highly vulnerable state. To reduce predation risks, cats prefer to rest in elevated positions so that predators are more visible to them and the cats, in turn, are more visually concealed from predators. 'In such a spot, predators can access cats only from below. Thus, their preference for resting in an elevated position can provide comfort, safety, and a clear vantage point for monitoring their environments. 'We hypothesised that a lateralised sleeping position further increases the chances of quickly detecting predators (or to identify careless prey) when awoken.' Threat-processing leftward bias Pregnant cows are known to prefer their left side while sleeping for a similar reason, experts believe. The scientists also found that the pawedness of a cat, whether it preferred its left or right side, is likely not to blame for the sleeping preference. A 2017 study found that male cats tend to prefer their left paws and females are more right-paw dominant. 'We are inclined to believe that the significant leftward bias in sleeping position in cats may have been evolutionarily driven by hemispheric asymmetries of threat processing,' the scientists add in their paper, published in the journal Current Biology.
Yahoo
27-06-2025
- Health
- Yahoo
Why cats prefer sleeping on their left side
Cats prefer to sleep on their left side to protect themselves from predators, a study has found. The pets sleep for up to 16 hours a day and often curl up or stretch out for a snooze in opportune places. But the way the animal settles down is not random, and there is an evolutionarily hard-wired logic underpinning it, according to a study from the Ruhr University Bochum in Germany. Scientists found cats lie on their left side around two-thirds of the time, which shows that it was done deliberately. They looked at clips on YouTube of more than 400 sleeping cats and logged which side they were sleeping on. Data revealed that 266 of the cats (66.5 per cent) were on their left side, leaving scientists to conclude this was a survival trait from their history in the wild. Sleeping on their left side means when they wake, their left eye is able to see the local area unobstructed by the cat's own body. This visual information is then processed by the right side of the brain. This hemisphere is what processes threats and is responsible for escaping danger as well as knowing an individual animal's position. This puts the cat at an advantage compared to if it was to sleep on its right side – when the information is processed by the left side of the brain, which is less specialised to aid a swift escape. This leftward preference is just one of the many ways in which cats protect themselves. 'Sleep is one of the most vulnerable states for an animal, as anti-predator vigilance is drastically reduced, especially in deep sleeping phases,' according to the study. 'Domestic cats are both predators and prey (e.g. for coyotes) and sleep an average of 12–16 hours a day. 'Therefore, they spend almost 60-65% of their lifetime in a highly vulnerable state. To reduce predation risks, cats prefer to rest in elevated positions so that predators are more visible to them and the cats, in turn, are more visually concealed from predators. 'In such a spot, predators can access cats only from below. Thus, their preference for resting in an elevated position can provide comfort, safety, and a clear vantage point for monitoring their environments. 'We hypothesised that a lateralised sleeping position further increases the chances of quickly detecting predators (or to identify careless prey) when awoken.' Pregnant cows are known to prefer their left side while sleeping for a similar reason, experts believe. The scientists also found that the pawedness of a cat, whether it preferred its left or right side, is likely not to blame for the sleeping preference. A 2017 study found that male cats tend to prefer their left paws and females are more right-paw dominant. 'We are inclined to believe that the significant leftward bias in sleeping position in cats may have been evolutionarily driven by hemispheric asymmetries of threat processing,' the scientists add in their paper, published in the journal Current Biology. Broaden your horizons with award-winning British journalism. Try The Telegraph free for 1 month with unlimited access to our award-winning website, exclusive app, money-saving offers and more.
