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Play and meaty food reduce hunting by cats

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Play and meaty food reduce hunting by cats

Domestic cats hunt wildlife less if owners play with them daily and feed them a meat-rich food, new research shows.

Hunting by cats is a conservation and welfare concern, but methods to reduce this are controversial and often rely on restricting cat behaviour in ways many owners find unacceptable.The new study — by the University of Exeter — found that introducing a premium commercial food where proteins came from meat reduced the number of prey animals cats brought home by 36%, and also that five to ten minutes of daily play with an owner resulted in a 25% reduction.

“Previous research in this area has focussed on inhibiting cats’ ability to hunt, either by keeping them indoors or fitting them with collars, devices and deterrents,” said Professor Robbie McDonald, of Exeter’s Environment and Sustainability Institute.

“While keeping cats indoors is the only sure-fire way to prevent hunting, some owners are worried about the welfare implications of restricting their cat’s outdoor access.

“Our study shows that — using entirely non-invasive, non-restrictive methods — owners can change what the cats themselves want to do.


“By playing with cats and changing their diets, owners can reduce their impact on wildlife without restricting their freedom.”

Play in the study involved owners simulating hunting by moving a feather toy on a string and wand so cats could stalk, chase and pounce. Owners also gave cats a toy mouse to play with after each “hunt,” mimicking a real kill.

It is not clear what elements of the meaty food led to the reduction in hunting.

“”Some cat foods contain protein from plant sources such as soy, and it is possible that despite forming a ‘complete diet’ these foods leave some cats deficient in one or more micronutrients -prompting them to hunt,” said Martina Cecchetti, the PhD student who conducted the experiments.

“However, meat production raises clear climate and environmental issues, so one of our next steps is to find out whether specific micronutrients could be added to cat foods to reduce hunting.


“We also plan to investigate whether different kinds of play have different effects, and whether combining strategies can reduce hunting even further.”

The study — based on a 12-week trial of 355 cats in 219 households in south-west England — also examined the effect of existing devices used to limit hunting by cats.

Colourful “Birdsbesafe” collar covers reduced numbers of birds captured and brought home by 42%, but had no effect on hunting of mammals.

Cat bells had no discernible overall effect — although the researchers say the impact on individual cats varied widely, suggesting some cats learn to hunt successfully despite wearing a bell.

Lisa George, from Helston in Cornwall, who looks after Minnie, a three-year-old tabby cat who took part in the trial, said: “Minnie loves to hunt. More often than not, she will bring her prey home and let it go in the house. We’ve had birds in the bedroom, rats in the waste paper bin (which took us three days to catch), rabbits in the utility room.

“On changing Minnie’s food (previously supermarket own-brand), to Lily’s Kitchen, I found she hardly hunted at all. This continued the whole time she was on this food. I can honestly say I couldn’t believe the difference as regards her hunting behaviour.”

George Bradley, from project sponsors SongBird Survival, said: “This latest study we have funded is excellent news for birds.

“The data show that cat owners (like me) can make a few small and easy steps to really improve the health and happiness of our pets as well as make a really big difference for all our wildlife, especially our beloved songbirds.

“Making these easy-to-implement changes will be a win-win for birds, cats and cat owners.”

Dr Sarah Ellis, Head of Cat Advocacy at iCatCare, which is part of the advisory group for this research project, said: “We are really encouraged by the findings of this study.

“While many cat owners are wildlife lovers and find the killing and injuring of wild animals by their cats upsetting, many owners also feel that keeping their cats indoors or restricting their outdoor access would impact negatively on their cats’ quality of life.

“At iCatCare, we are particularly excited about the positive effects of play — this is an activity that owners can easily introduce at no or little cost, takes little time and is very cat-friendly.

“”The mental and physical stimulation of predatory-like play are likely to help keep a cat in tip top condition and provide an appropriate behavioural outlet for its predatory behaviours.””

Dr Adam Grogan, Head of Wildlife at the RSPCA, welcomed the results of the study.

“The RSPCA cares for both cats and wild animals and we want to provide advice to cat owners that will benefit both cat and wild animal welfare,” he said.

“This project provides us with alternatives for cat owners that are simple and effective and so easy to adopt.”

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Long-period oscillations control the Sun’s differential rotation

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Play and meaty food reduce hunting by cats


The Sun’s differential rotation pattern has puzzled scientists for decades: while the poles rotate with a period of approximately 34 days, mid-latitudes rotate faster and the equatorial region requires only approximately 24 days for a full rotation. In addition, in past years advances in helioseismology, i.e. probing the solar interior with the help of solar acoustic waves, have established that this rotational profile is nearly constant throughout the entire convection zone. This layer of the Sun stretches from a depth of approximately 200,000 kilometers to the visible solar surface and is home to violent upheavals of hot plasma which play a crucial role in driving solar magnetism and activity.

While theoreticaThe interior of the Sun does not rotate at the same rate at all latitudes. The physical origin of this differential rotation is not fully understood. A team of scientists at the Max Planck Institute for Solar System Research (MPS) in Germany has made a ground-breaking discovery. As the team reports today in the journal Science Advances, the long-period solar oscillations discovered by MPS scientists in 2021 play a crucial role in controlling the Sun’s rotational pattern. The long-period oscillations are analogous to the baroclinically unstable waves in Earth’s atmosphere that shape the weather. In the Sun, these oscillations carry heat from the slightly hotter poles to the slightly cooler equator. To obtain their new results, the scientists interpreted observations from NASA’s Solar Dynamics Observatory using cutting-edge numerical simulations of the solar interior. They found that the difference in temperature between the poles and the equator is about seven degrees.

l models have long postulated a slight temperature difference between solar poles and equator to maintain the Sun’s rotational pattern, it has proven notoriously difficult to measure. After all, observations have to “look through” the background of the Sun’s deep interior which measures up to million degrees in temperature. However, as the researchers from MPS show, it is now possible to determine the temperature difference from the observations of the long-period oscillations of the Sun.

In their analysis of observational data obtained by the Helioseismic and Magnetic Imager (HMI) onboard NASA’s Solar Dynamics Observatory from 2017 to 2021, the scientists turned to global solar oscillations with long periods that can be discerned as swirling motions at the solar surface. Scientists from MPS reported their discovery of these inertial oscillations three years ago. Among these observed modes, the high-latitude modes with velocities of up to 70 km per hour, proved to be especially influential.

To study the nonlinear nature of these high-latitude oscillations, a set of three-dimensional numerical simulations was conducted. In their simulations, the high-latitude oscillations carry heat from the solar poles to the equator, which limits the temperature difference between the Sun’s poles and the equator to less than seven degrees. “This very small temperature difference between the poles and the equator controls the angular momentum balance in the Sun and thus is an important feedback mechanism for the Sun’s global dynamics” says MPS Director Prof. Dr. Laurent Gizon.

In their simulations, the researchers for the first time described the crucial processes in a fully three-dimensional model. Former endeavors had been limited to two-dimensional approaches that assumed the symmetry about the Sun’s rotation axis. “Matching the nonlinear simulations to the observations allowed us to understand the physics of the long-period oscillations and their role in controlling the Sun’s differential rotation,” says MPS postdoc and the lead author of the study, Dr. Yuto Bekki.

The solar high-latitude oscillations are driven by a temperature gradient in a similar way to extratropical cyclones on the Earth. The physics is similar, though the details are different: “In the Sun, the solar pole is about seven degrees hotter than equator and this is enough to drive flows of about 70 kilometers per hour over a large fraction of the Sun. The process is somewhat similar to the driving of cyclones,” says MPS scientist Dr. Robert Cameron.

Probing the physics of the Sun’s deep interior is difficult. This study is important as it shows that the long-period oscillations of the Sun are not only useful probes of the solar interior, but that they play an active role in the way the Sun works. Future work, which will be carried out in the context of the ERC Synergy Grant WHOLESUN and the DFG Collaborative Research Center 1456 Mathematics of Experiments, will be aimed at better understanding the role of these oscillations and their diagnostic potential.



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Artificial reef designed by MIT engineers could protect marine life, reduce storm damage

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The beautiful, gnarled, nooked-and-crannied reefs that surround tropical islands serve as a marine refuge and natural buffer against stormy seas. But as the effects of climate change bleach and break down coral reefs around the world, and extreme weather events become more common, coastal communities are left increasingly vulnerable to frequent flooding and erosion.

An MIT team is now hoping to fortify coastlines with “architected” reefs — sustainable, offshore structures engineered to mimic the wave-buffering effects of natural reefs while also providing pockets for fish and other marine life.

The team’s reef design centers on a cylindrical structure surrounded by four rudder-like slats. The engineers found that when this structure stands up against a wave, it efficiently breaks the wave into turbulent jets that ultimately dissipate most of the wave’s total energy. The team has calculated that the new design could reduce as much wave energy as existing artificial reefs, using 10 times less material.

The researchers plan to fabricate each cylindrical structure from sustainable cement, which they would mold in a pattern of “voxels” that could be automatically assembled, and would provide pockets for fish to explore and other marine life to settle in. The cylinders could be connected to form a long, semipermeable wall, which the engineers could erect along a coastline, about half a mile from shore. Based on the team’s initial experiments with lab-scale prototypes, the architected reef could reduce the energy of incoming waves by more than 95 percent.

“This would be like a long wave-breaker,” says Michael Triantafyllou, the Henry L. and Grace Doherty Professor in Ocean Science and Engineering in the Department of Mechanical Engineering. “If waves are 6 meters high coming toward this reef structure, they would be ultimately less than a meter high on the other side. So, this kills the impact of the waves, which could prevent erosion and flooding.”

Details of the architected reef design are reported today in a study appearing in the open-access journal PNAS Nexus. Triantafyllou’s MIT co-authors are Edvard Ronglan SM ’23; graduate students Alfonso Parra Rubio, Jose del Auila Ferrandis, and Erik Strand; research scientists Patricia Maria Stathatou and Carolina Bastidas; and Professor Neil Gershenfeld, director of the Center for Bits and Atoms; along with Alexis Oliveira Da Silva at the Polytechnic Institute of Paris, Dixia Fan of Westlake University, and Jeffrey Gair Jr. of Scinetics, Inc.

Leveraging turbulence

Some regions have already erected artificial reefs to protect their coastlines from encroaching storms. These structures are typically sunken ships, retired oil and gas platforms, and even assembled configurations of concrete, metal, tires, and stones. However, there’s variability in the types of artificial reefs that are currently in place, and no standard for engineering such structures. What’s more, the designs that are deployed tend to have a low wave dissipation per unit volume of material used. That is, it takes a huge amount of material to break enough wave energy to adequately protect coastal communities.

The MIT team instead looked for ways to engineer an artificial reef that would efficiently dissipate wave energy with less material, while also providing a refuge for fish living along any vulnerable coast.

“Remember, natural coral reefs are only found in tropical waters,” says Triantafyllou, who is director of the MIT Sea Grant. “We cannot have these reefs, for instance, in Massachusetts. But architected reefs don’t depend on temperature, so they can be placed in any water, to protect more coastal areas.”

The new effort is the result of a collaboration between researchers in MIT Sea Grant, who developed the reef structure’s hydrodynamic design, and researchers at the Center for Bits and Atoms (CBA), who worked to make the structure modular and easy to fabricate on location. The team’s architected reef design grew out of two seemingly unrelated problems. CBA researchers were developing ultralight cellular structures for the aerospace industry, while Sea Grant researchers were assessing the performance of blowout preventers in offshore oil structures — cylindrical valves that are used to seal off oil and gas wells and prevent them from leaking.

The team’s tests showed that the structure’s cylindrical arrangement generated a high amount of drag. In other words, the structure appeared to be especially efficient in dissipating high-force flows of oil and gas. They wondered: Could the same arrangement dissipate another type of flow, in ocean waves?

The researchers began to play with the general structure in simulations of water flow, tweaking its dimensions and adding certain elements to see whether and how waves changed as they crashed against each simulated design. This iterative process ultimately landed on an optimized geometry: a vertical cylinder flanked by four long slats, each attached to the cylinder in a way that leaves space for water to flow through the resulting structure. They found this setup essentially breaks up any incoming wave energy, causing parts of the wave-induced flow to spiral to the sides rather than crashing ahead.

“We’re leveraging this turbulence and these powerful jets to ultimately dissipate wave energy,” Ferrandis says.

Standing up to storms

Once the researchers identified an optimal wave-dissipating structure, they fabricated a laboratory-scale version of an architected reef made from a series of the cylindrical structures, which they 3D-printed from plastic. Each test cylinder measured about 1 foot wide and 4 feet tall. They assembled a number of cylinders, each spaced about a foot apart, to form a fence-like structure, which they then lowered into a wave tank at MIT. They then generated waves of various heights and measured them before and after passing through the architected reef.

“We saw the waves reduce substantially, as the reef destroyed their energy,” Triantafyllou says.

The team has also looked into making the structures more porous, and friendly to fish. They found that, rather than making each structure from a solid slab of plastic, they could use a more affordable and sustainable type of cement.

“We’ve worked with biologists to test the cement we intend to use, and it’s benign to fish, and ready to go,” he adds.

They identified an ideal pattern of “voxels,” or microstructures, that cement could be molded into, in order to fabricate the reefs while creating pockets in which fish could live. This voxel geometry resembles individual egg cartons, stacked end to end, and appears to not affect the structure’s overall wave-dissipating power.

“These voxels still maintain a big drag while allowing fish to move inside,” Ferrandis says.

The team is currently fabricating cement voxel structures and assembling them into a lab-scale architected reef, which they will test under various wave conditions. They envision that the voxel design could be modular, and scalable to any desired size, and easy to transport and install in various offshore locations. “Now we’re simulating actual sea patterns, and testing how these models will perform when we eventually have to deploy them,” says Anjali Sinha, a graduate student at MIT who recently joined the group.

Going forward, the team hopes to work with beach towns in Massachusetts to test the structures on a pilot scale.

“These test structures would not be small,” Triantafyllou emphasizes. “They would be about a mile long, and about 5 meters tall, and would cost something like 6 million dollars per mile. So it’s not cheap. But it could prevent billions of dollars in storm damage. And with climate change, protecting the coasts will become a big issue.”

This work was funded, in part, by the U.S. Defense Advanced Research Projects Agency.



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Persistent hiccups in a far-off galaxy draw astronomers to new black hole behavior

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At the heart of a far-off galaxy, a supermassive black hole appears to have had a case of the hiccups.

Astronomers from MIT, Italy, the Czech Republic, and elsewhere have found that a previously quiet black hole, which sits at the center of a galaxy about 800 million light years away, has suddenly erupted, giving off plumes of gas every 8.5 days before settling back to its normal, quiet state.

The periodic hiccups are a new behavior that has not been observed in black holes until now. The scientists believe the most likely explanation for the outbursts stems from a second, smaller black hole that is zinging around the central, supermassive black hole and slinging material out from the larger black hole’s disk of gas every 8.5 days.

The team’s findings, which will be published in the journal Science Advances, challenge the conventional picture of black hole accretion disks, which scientists had assumed are relatively uniform disks of gas that rotate around a central black hole. The new results suggest that accretion disks may be more varied in their contents, possibly containing other black holes, and even entire stars.

“We thought we knew a lot about black holes, but this is telling us there are a lot more things they can do,” says study author Dheeraj “DJ” Pasham, a research scientist in MIT’s Kavli Institute for Astrophysics and Space Research. “We think there will be many more systems like this, and we just need to take more data to find them.”

The study’s MIT co-authors include postdoc Peter Kosec, graduate student Megan Masterson, Associate Professor Erin Kara, Principal Research Scientist Ronald Remillard, and former research scientist Michael Fausnaugh, along with collaborators from multiple institutions, including the Tor Vergata University of Rome, the Astronomical Institute of the Czech Academy of Sciences, and Masaryk University in the Czech Republic.

“Use it or lose it”

The team’s findings grew out of an automated detection by ASAS-SN (the All Sky Automated Survey for SuperNovae), a network of 20 robotic telescopes situated in various locations across the northern and southern hemispheres. The telescopes automatically survey the entire sky once a day for signs of supernovae and other transient phenomena.

In December of 2020, the survey spotted a burst of light in a galaxy about 800 million light years away. That particular part of the sky had been relatively quiet and dark until the telescopes’ detection, when the galaxy suddenly brightened by a factor of 1,000. Pasham, who happened to see the detection reported in a community alert, chose to focus in on the flare with NASA’s NICER (the Neutron star Interior Composition Explorer), an X-ray telescope aboard the International Space Station that continuously monitors the sky for X-ray bursts that could signal activity from neutron stars, black holes, and other extreme gravitational phenomena. The timing was fortuitous, as it was getting toward the end of Pasham’s year-long period during which he had permission to point, or “trigger” the telescope.

“It was either use it or lose it, and it turned out to be my luckiest break,” he says.

He trained NICER to observe the far-off galaxy as it continued to flare. The outburst lasted for about four months before petering out. During that time, NICER took measurements of the galaxy’s X-ray emissions on a daily, high-cadence basis. When Pasham looked closely at the data, he noticed a curious pattern within the four-month flare: subtle dips, in a very narrow band of X-rays, that seemed to reappear every 8.5 days.

It seemed that the galaxy’s burst of energy periodically dipped every 8.5 days. The signal is similar to what astronomers see when an orbiting planet crosses in front of its host star, briefly blocking the star’s light. But no star would be able to block a flare from an entire galaxy.

“I was scratching my head as to what this means because this pattern doesn’t fit anything that we know about these systems,” Pasham recalls.

Punch it

As he was looking for an explanation to the periodic dips, Pasham came across a recent paper by theoretical physicists in the Czech Republic. The theorists had separately worked out that it would be possible, in theory, for a galaxy’s central supermassive black hole to host a second, much smaller black hole. That smaller black hole could orbit at an angle from its larger companion’s accretion disk.

As the theorists proposed, the secondary would periodically punch through the primary black hole’s disk as it orbits. In the process, it would release a plume of gas , like a bee flying through a cloud of pollen. Powerful magnetic fields, to the north and south of the black hole, could then slingshot the plume up and out of the disk. Each time the smaller black hole punches through the disk, it would eject another plume, in a regular, periodic pattern. If that plume happened to point in the direction of an observing telescope, it might observe the plume as a dip in the galaxy’s overall energy, briefly blocking the disk’s light every so often.

“I was super excited by this theory, and I immediately emailed them to say, ‘I think we’re observing exactly what your theory predicted,'” Pasham says.

He and the Czech scientists teamed up to test the idea, with simulations that incorporated NICER’s observations of the original outburst, and the regular, 8.5-day dips. What they found supports the theory: The observed outburst was likely a signal of a second, smaller black hole, orbiting a central supermassive black hole, and periodically puncturing its disk.

Specifically, the team found that the galaxy was relatively quiet prior to the December 2020 detection. The team estimates the galaxy’s central supermassive black hole is as massive as 50 million suns. Prior to the outburst, the black hole may have had a faint, diffuse accretion disk rotating around it, as a second, smaller black hole, measuring 100 to 10,000 solar masses, was orbiting in relative obscurity.

The researchers suspect that, in December 2020, a third object — likely a nearby star — swung too close to the system and was shredded to pieces by the supermassive black hole’s immense gravity — an event that astronomers know as a “tidal disruption event.” The sudden influx of stellar material momentarily brightened the black hole’s accretion disk as the star’s debris swirled into the black hole. Over four months, the black hole feasted on the stellar debris as the second black hole continued orbiting. As it punched through the disk, it ejected a much larger plume than it normally would, which happened to eject straight out toward NICER’s scope.

The team carried out numerous simulations to test the periodic dips. The most likely explanation, they conclude, is a new kind of David-and-Goliath system — a tiny, intermediate-mass black hole, zipping around a supermassive black hole.

“This is a different beast,” Pasham says. “It doesn’t fit anything that we know about these systems. We’re seeing evidence of objects going in and through the disk, at different angles, which challenges the traditional picture of a simple gaseous disk around black holes. We think there is a huge population of these systems out there.”

“This is a brilliant example of how to use the debris from a disrupted star to illuminate the interior of a galactic nucleus which would otherwise remain dark. It is akin to using fluorescent dye to find a leak in a pipe,” says Richard Saxton, an X-ray astronomer from the European Space Astronomy Centre (ESAC) in Madrid, Spain, who was not involved in the study. “This result shows that very close super-massive black hole binaries could be common in galactic nuclei, which is a very exciting development for future gravitational wave detectors.”

This research was supported in part NASA.



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