Current rates of plastic emissions globally may trigger effects that we will not be able to reverse, argues a new study by researchers from Sweden, Norway and Germany published on July 2nd in Science. According to the authors, plastic pollution is a global threat, and actions to drastically reduce emissions of plastic to the environment are "the rational policy response."

Plastic is found everywhere on the planet: from deserts and mountaintops to deep oceans and Arctic snow. As of 2016, estimates of global emissions of plastic to the world's lakes, rivers and oceans ranged from 9 to 23 million metric tons per year, with a similar amount emitted onto land yearly. These estimates are expected to almost double by 2025 if business-as-usual scenarios apply.

"Plastic is deeply engrained in our society, and it leaks out into the environment everywhere, even in countries with good waste-handling infrastructure," says Matthew MacLeod, Professor at Stockholm University and lead author of the study. He says that emissions are trending upward even though awareness about plastic pollution among scientists and the public has increased significantly in recent years.

That discrepancy is not surprising to Mine Tekman, a PhD candidate at the Alfred Wegener Institute in Germany and co-author of the study, because plastic pollution is not just an environmental issue but also a "political and economic" one. She believes that the solutions currently on offer, such as recycling and cleanup technologies, are not sufficient, and that we must tackle the problem at its root.

"The world promotes technological solutions for recycling and to remove plastic from the environment. As consumers, we believe that when we properly separate our plastic trash, all of it will magically be recycled. Technologically, recycling of plastic has many limitations, and countries that have good infrastructures have been exporting their plastic waste to countries with worse facilities. Reducing emissions requires drastic actions, like capping the production of virgin plastic to increase the value of recycled plastic, and banning export of plastic waste unless it is to a country with better recycling" says Tekman.

A poorly reversible pollutant of remote areas of the environment

Plastic accumulates in the environment when amounts emitted exceed those that are removed by cleanup initiatives and natural environmental processes, which occurs by a multi-step process known as weathering.

"Weathering of plastic happens because of many different processes, and we have come a long way in understanding them. But weathering is constantly changing the properties of plastic pollution, which opens new doors to more questions," says Hans Peter Arp, researcher at the Norwegian Geotechnical Institute (NGI) and Professor at the Norwegian University of Science and Technology (NTNU) who has also co-authored the study. "Degradation is very slow and not effective in stopping accumulation, so exposure to weathered plastic will only increase," says Arp. Plastic is therefore a "poorly reversible pollutant," both because of its continuous emissions and environmental persistence.

Remote environments are particularly under threat as co-author Annika Jahnke, researcher at the Helmholtz Centre for Environmental Research (UFZ) and Professor at the RWTH Aachen University explains:

"In remote environments, plastic debris cannot be removed by cleanups, and weathering of large plastic items will inevitably result in the generation of large numbers of micro- and nanoplastic particles as well as leaching of chemicals that were intentionally added to the plastic and other chemicals that break off the plastic polymer backbone. So, plastic in the environment is a constantly moving target of increasing complexity and mobility. Where it accumulates and what effects it may cause are challenging or maybe even impossible to predict."

A potential tipping point of irreversible environmental damage

On top of the environmental damage that plastic pollution can cause on its own by entanglement of animals and toxic effects, it could also act in conjunction with other environmental stressors in remote areas to trigger wide-ranging or even global effects. The new study lays out a number of hypothetical examples of possible effects, including exacerbation of climate change because of disruption of the global carbon pump, and biodiversity loss in the ocean where plastic pollution acts as additional stressor to overfishing, ongoing habitat loss caused by changes in water temperatures, nutrient supply and chemical exposure.

Taken all together, the authors view the threat that plastic being emitted today may trigger global-scale, poorly reversible impacts in the future as "compelling motivation" for tailored actions to strongly reduce emissions.

"Right now, we are loading up the environment with increasing amounts of poorly reversible plastic pollution. So far, we don't see widespread evidence of bad consequences, but if weathering plastic triggers a really bad effect we are not likely to be able to reverse it," cautions MacLeod. "The cost of ignoring the accumulation of persistent plastic pollution in the environment could be enormous. The rational thing to do is to act as quickly as we can to reduce emissions of plastic to the environment."

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Source: Stockholm University

The stink of ammonia in urine, sweat, and rotting meat repels humans, but many insects find ammonia alluring. Now, UConn researchers have figured out how the annoying insects smell it, a discovery that could lead to better ways to make them buzz off.

The sense of smell is enormously important. Mammals devote a third of their genetic code to odor receptors found in the nose, and have more than 1,000 different kinds that allow us to smell an estimated trillion different odors.

Flies don't have noses. Instead, they smell with their antenna. Each antenna is covered with tiny hairs called sensilla. Each sensilla contains a few neurons -- fly brain cells. Each neuron expresses one type of odor receptor, and they all fall into two main classes. Or so scientists thought.

But recent work by UConn neuroscientist Karen Menuz and her colleagues, reported online in June in Current Biology, identified a new type of odor neuron devoted to sniffing ammonia. And the receptor it uses is unlike any other odor receptor known.

Flies and other insects use the scent of ammonia to find food sources. Mosquitoes find humans to bite by following the faint scent of ammonia in our sweat, along with other clues. Many crop pests do the same, locating fruit and agricultural products to infest and consume. "When an odor binds to a receptor, the cell depolarizes, and sends a signal saying 'hey, the odor is here!' Insects are small, and odors come in plumes, so most insects will fly straight as long as the concentration is the same or growing. If they lose the odor plume, they'll do a casting behavior, flying in zig zags to find it," Menuz says.

Knowing exactly how the insects smell ammonia might yield effective ways to block them from following that scent plume -- and from finding us and our crops.

But figuring out exactly how and what a fly smells is tricky. Menuz and her colleagues are able to gently hold a fly down and use incredibly fine pieces of glass to probe individual neurons in sensilla on the fly's antenna. Then they let the ammonia waft.

They probed all three types of scent neurons in the flies' sensilla, but they didn't respond to ammonia. But the fly was obviously smelling it. So the researchers realized there had to be a fourth scent neuron they hadn't known was there. And they found it -- but it didn't seem to have the usual odor receptors on it. It was covered in ammonia transporter (Amt) a molecule that is known to allow ammonia in and out of cells.

No one had ever known a transporter molecule to also act as an odor receptor. But there it was. When they selectively killed off only that type of neuron, the flies did not respond to ammonia at all. And when the team forced scent neurons that don't normally respond to ammonia to express Amt on their surfaces, those neurons began responding to ammonia, too.

The team hopes to learn whether mosquitoes use the same system to smell ammonia. If it's used by both mosquitoes and flies, it's a good bet the Amt receptor-as-sniffer is used by all insects, and developing ways to block Amt could be an effective way to protect people and crops from pests attracted to ammonia.

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Despite a name straight from a Tarantino movie, natural killer (NK) cells are your allies when it comes to fighting infections and cancer. If T cells are like a team of specialist doctors in an emergency room, NK cells are the paramedics: They arrive first on the scene and perform damage control until reinforcements arrive.

Part of our innate immune system, which dispatches these first responders, NK cells are primed from birth to recognize and respond to danger. Learning what fuels NK cells is an active area of research in immunology, with important clinical implications.

"There's a lot of interest right now in NK cells as a potential target of immunotherapy," says Joseph Sun, an immunologist in the Sloan Kettering Institute. "The more we can understand what drives these cells, the better we can program them to fight disease."

First in Line

Previous work from researchers at MSK and elsewhere has shown that T cells rely on aerobic glycolysis to carry out their protective functions. But whether NK cells depend on this form of metabolism to power their own activities was not known.

Because Dr. Sun and his colleagues studied NK cells in animals instead of a dish, they could establish what type of metabolism NK cells use and compare it to T cells in a natural setting. They found that NK cells ramp up aerobic glycolysis about five days prior to when T cells respond with their own glycolytic surge.

"This fits with the idea that NK cells are innate immune cells that are really critical for mounting a rapid response," Dr. Sheppard says.

The findings are relevant to ongoing efforts to use NK cells as immunotherapy in people with cancer and other conditions. In particular, they have implications for using NK cells as a form of cell therapy -- when cells are grown outside a patient and then infused back into the patient's blood.

"If you're growing these cells in a dish and you push them to divide too rapidly, they may not have as much potential to undergo aerobic glycolysis when you put them into a patient," Dr. Sheppard says.

The takeaway for researchers designing clinical trials is this: They must find a balance between encouraging NK cells to multiply and preserving their stamina. These NK cells are the paramedics of our immune system, so it's important to keep them speedy and responsive.

The findings were reported June 1, 2021, in the journal Cell Reports.

This research was supported by the Cancer Research Institute, the NCI Cancer Center Support Grant (P30CA08748), Cycle for Survival, the Ludwig Center for Cancer Immunotherapy, the American Cancer Society, the Burroughs Wellcome Fund, and the NIH (grants AI100874, AI130043, AI155558). The study authors declare no conflicts of interest.

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It took us almost two months to comb through dad's house, sorting the myriad pieces of his unpursued passions into several appropriate piles for disposal.

• Keep.
• Sell.
• Donate.
• Trash.

He didn't have much in the way of food, but cookbooks in mint condition spilled out of his kitchen cupboards. Mystery novels were stacked neatly on his bedside table, suffocating under layers of dust. Princess Di's biography and Stephen King's The Shining lay face down on the coffee table, spines cracked towards the ceiling. Poets hid, forgotten, behind the basement bar. Daunting masterpieces of Joyce, Hugo, and Dumas stood proper and pristine in the bookcases of his spare bedroom. Harry Potter, curiously, was lined up neatly on the workbench in his garage next to an impressive collection of equipment manuals. Donate.

While I examined every paternal artifact with the zeal of an amateur archaeologist, my sister, Kate, executed our job grudgingly, methodically, the corners of her mouth tugged down in mild distaste. She held no curiosity for the life that gave us life, and I assumed her interest in him extended only as far as his had in her.

We waded through a world of short-lived hobbies. The shed in the yard boarded gleaming gardening tools, unspoiled art supplies, and a pair of cross country skis still marked with a discount sticker. Sell.

We purged every nook and cranny in the house of unused useful treasures. Three hundred glass mason jars collected dust and spiders in the alcove under the stairs; forty-five rolls of scotch tape curled up on their sides, stacked haphazardly in the cupboard above the washing machine; three five-gallon pails of assorted nails, screws, and bolts rusted behind the furnace. Keep. Donate. Trash.

A Yamaha keyboard piano emerged from under piles of forgotten laundry. Sell. Beginner sheet music for the guitar we'd never heard him play was buried in a wicker basket under a cascading mountain of magazines. The guitar in question was wildly out of tune. I strummed a dissonant chord absentmindedly, prompting Kate to grab and drop it with a reverberating hum next to a harmonica, a violin bow, and an assortment of small percussion instruments. Donate.

"We could sell that!" I exclaimed.

"He bought it at Walmart," she replied flatly, and I briefly wondered how she knew.

Dad hadn't been a bad guy, as far as I remember. I recalled him doing all the right dad things "teaching me to throw and catch a ball, taking us to the county fair to eat too much candy, bringing home a wriggling bundle of floppy ears and sad eyes that we crossed our hearts to feed, train, and walk (naturally, and much to her disgruntled dismay, it became mom's exclusive responsibility)".

It was just that, between the checked boxes of fatherhood, absence was his only constant.

Early on, it was missed birthdays, disappointing Christmas mornings, and an empty seat in the stands at my B Division hockey games. By the time I was ten, he banged through our door only once or twice a year. Kate would quietly disappear to a friend's; mom would gravitate as if on auto-pilot into the kitchen to prepare a meal; I would hover, eager to brief him on my latest activities and accomplishments, hopeful he would finally divulge something about the band with which he was surely traveling, or the secret mission on which he must have been deployed. "This and that" was all he ever offered.

When Kate left home, he came around even less often.

I waded into the unmired moodiness of my teenage years and developed (feigned) indifference in his disinterest. By the time I crashed clumsily from adolescence to adulthood, dad was a sort of non-entity that flitted and fluttered at the edges. He attended my university convocation, but didn't stick around for the celebratory dinner. He stood by us at mom's funeral, appropriately sad, but left us to make the arrangements and deal with her estate. He was invited to Kate's wedding, but she asked me to walk her down the aisle.

At Kate's orders, I tackled the bedroom, while she disappeared for days under unreasonable hoards of wooden spoons, tacky coffee mugs, and canned goods. The stench of sickness still clung to his mattress and its clothes. Trash. The neglected novels on his bedside table were jacketed in dust and blanketed in crusty tissues. Trash. Drawers were mostly empty save for a rolling lip chap and a handful of loose change. The rest of the furniture appeared in fine health. Sell.

Rifling through his closet, I found only a few crumpled receipts in the pockets of his clothes. Donate. My climbing bewilderment and disappointment reached their peak. A lifetime of pretending not to care aside, we finally had unfettered access to the private life of our flighty father. I wanted to find a trunk of sentimental memories in his basement, or a shoe box of photographs labelled with hard-to-read names stuffed in the closet, or a stack of secret-littered journals on the bookshelves. But the modest 900 square-foot house rejected my foolish fantasies.

Last year, Kate had learned dad was unwell. "Oh, by the way," she hesitantly tacked on to our annual phone call, "Dad's been in the hospital."

I paused, caught off guard by her mention of his existence and, further, her awareness of his illness. I'd wanted to know more "what was wrong, should we go visit, who was taking care of him, who called her" but my tyrant nephews were wailing in the background, and she took advantage of my silent beat to skewer the conversation. "He's fine now, at home, I guess. Listen, don't worry about it" She trailed off as the cacophony of family anarchy rose with a mighty crescendo, and the line died.

I didn't call back, and neither did she. The next time we spoke, she delivered a dispassionate dispatch. "He's dead."

Now we stand among life's leftovers.

• Keep. Empty.
• Sell. Posted.
• Donate. Boxed.
• Trash. Bagged.

There is no heirloom-worthy jewelry. There are no old family photos. There aren't any accolades or love letters, not even a final will and testament. Nothing in seventy years' worth of accumulation sheds a shred of light on who dad was or why.

I watch my sister lug bags and boxes out the door, and wish there was someone left who knew him.

When the trucks are packed and the house echoes in vacant relief, we stand on the front porch and watch the realtor pound a For Sale sign into the frosty lawn. I mutter, "I should have gone to see him, you know, before&"

Kate turns and looks up at me with the most peculiar expression of incredulity. She puts her gloved hand on my arm. For a long quiet moment it feels like she's trying to convey something important, but all she leaves me with is: "See you at Christmas."

And then she's gone without looking back, bounding down the cracked concrete towards her car with a lightness in her step I've never seen before.

Credit: Christina Marie

Humans can observe what and where something happens around them with their hearing, as long as sound frequencies lie between 20 Hz and 2,000 Hz. Researchers at Aalto University have now developed a new audio technique that enables people to also hear ultrasonic sources that generate sound at frequencies above 20,000 Hz with simultaneous perception of their direction. The results have been published in Scientific Reports on 2 June 2021.

'In our study, we used bats in their natural habitat as sources of ultrasonic sound. With our new technique, we can now hear the directions-of-arrival of bat sounds, which means we can track bats in flight and hear where they are -- we're essentially giving ourselves super hearing,' says Professor Ville Pulkki from Aalto University.

Small devices have been used before to listen to bats but previous versions haven't allowed listeners to locate the bats, just hear them. With their device the researchers record ultrasound using an array of microphones flush mounted and uniformly distributed on the surface of a small sphere. After the signal has been pitch-shifted to audible frequencies, the sound is played back on the headphones immediately. Currently, the pitch-shifting is performed on a computer, but, in the future, it could be done with electronics attached to the headphones.

'A sound-field analysis is performed on the microphone signals, and as a result we obtain the most prominent direction of the ultrasonic sound field and a parameter that suggests that the sound comes only from a single source. After this, a single microphone signal is brought to the audible frequency range of human hearing and its single-source signal is played back on the headphones so that the listener can perceive the source from the direction the sound was analysed to arrive,' Pulkki says.

On top of its popular appeal, the technique has tangible real-world applications.

'In science and art, people have always been interested in how they could improve their senses. Finding sources of ultrasonic sound is also useful in many practical situations, such as finding leaks in pressurized gas pipes. Minor pipe leaks often produce strong ultrasound emissions not detected by normal hearing. The device allows us to spot the sound source quickly,' Pulkki explains.

'Sometimes, damaged electrical equipment also emit ultrasound, and the device could be used for locating faulty equipment faster in places such as data centres,' he continues.

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