News Feeds

An upright neuroimaging device developed by neuroscientists, physicists and engineers allows patients to move around while undergoing a brain scan.

More and more parents are choosing to only have one child. Here’s what the evidence says about how growing up without siblings affects their personality traits and well-being

More and more parents are choosing to only have one child. Here’s what the evidence says about how growing up without siblings affects their personality traits and well-being

How do you get an atmosphere at a world that doesn’t have one and can’t keep one? If it’s the Moon, you simply bombard it for millions of years with tiny meteorites. Also, let it sit in the solar wind and see what happens. Both space-weathering processes create a thin “exosphere” just above the lunar surface.

Scientists call the first process “impact vaporization” and now suspect that it’s a major reason the lunar atmosphere exists. It also helps explain how atmospheric atoms escape from the Moon to space.

A team of scientists at MIT and the University of Chicago recently published a paper describing their research into the space weathering causes of the lunar exosphere. It pinpoints the process of impact vaporization as a major player. “We give a definitive answer that meteorite impact vaporization is the dominant process that creates the lunar atmosphere,” says the study’s lead author, Nicole Nie, an assistant professor in MIT’s Department of Earth, Atmospheric and Planetary Sciences. “The Moon is close to 4.5 billion years old, and through that time the surface has been continuously bombarded by meteorites. We show that eventually, a thin atmosphere reaches a steady state because it’s being continuously replenished by small impacts all over the Moon.”

Tracking the Space Weathering Influence on the Moon’s Atmosphere

Researchers have known about the lunar atmosphere for decades. It was first observed in the 1980s as a layer of atoms hugging close to the surface. The LADEE mission specifically studied that exosphere. The atoms don’t just lie there, however. They bounce around, largely stirred up by constant impacts of tiny objects called micrometeoroids. Those dust-sized particles—along with larger objects smacking into the surface—kick up the lunar soil. That vaporizes some of the atoms of material—including potassium and rubidium. Those atoms are suspended in the thin exosphere. Or, if they get enough velocity in the weak lunar gravity, they escape to space.

The different ways that space weathering can affect the lunar surface. Cartoon by IntrplnetSarah, Creative Commons Attribution-ShareAlike 3.0

The MIT/Chicago team members wanted to prove the exosphere is produced by this impact vaporization component of space weathering. So, they analyzed samples of lunar soil collected during the Apollo missions. They zeroed in on the potassium and rubidium content. That’s because those elements vaporize easily. If the Moon’s atmosphere is atoms suspended above the surface, lighter isotopes of those atoms should be more easily lofted. The heavier isotopes are more likely to settle back in the soil. Furthermore, scientists predict that impact vaporization, and ion sputtering, should result in very different isotopic proportions in the soil. The specific ratio of light to heavy isotopes that remain in the soil, for both elements they tested, eventually proved that impact-related vaporization is an important part of exosphere creation.

The Solar Wind’s Effect on the Moon

The solar wind also plays a role in creating the Moon’s exosphere. That occurs as the ionized particles in the solar wind ions interact with the surface and “sputter off” neutral atoms. Not only does this process contribute to the creation of an exosphere, but it also affects the erosion of materials on the Moon. The current MIT/Chicago study, however, pinpoints the constant rain of impacts as a significant contributor and the two processes work together to create the lunar exosphere.

“With impact vaporization, most of the atoms would stay in the lunar atmosphere, whereas with ion sputtering, a lot of atoms would be ejected into space,” Nie said. “From our study, we now can quantify the role of both processes, to say that the relative contribution of impact vaporization versus ion sputtering is about 70:30 or larger.”

Space Weathering and Future Missions

So, about 70 percent or more of the lunar exosphere is a product of meteorite impacts. The rest occurs thanks to the incessant influence of the solar wind. While this space weathering activity doesn’t produce anything like a breathable atmosphere that future lunar explorers could breathe, it does give insight into the processes that affect the Moon.

Both meteoritic bombardments and solar wind activity pose continuing risks to lunar visitors and their infrastructure. In addition to simply understanding the evolution of the lunar surface and atmosphere, such studies will be useful to anyone who seeks to build—and live—on the Moon in the future.

For More Information

Scientists Pin Down the Origins of the Moon’s Tenuous Atmosphere
Lunar Soil Record of Atmosphere Lost over Eons

The post The Moon’s Atmosphere Comes from Space Weathering appeared first on Universe Today.

It was a tough journey to get here, but I finally arrived in Cape Town last night, exhausted, filthy (no change of clothes from last Saturday until this morning: Wednesday) due to various ariling foulups (thanks, United!).

I am staying with old friends, Martim (botanist) and Rita (evolutionary ornithologist) in a beautiful cottage by the ocean; I’m told that whales sometimes show up below with their calves.  Here’s the view from the balcony outside my bedroom. The Cape of Good Hope—the southern tip of South Africa, is the left tip of the peninsula in the background.

I was supposed to fly out of Dulles Airport in Washinton last Saturday, but after we arrived, there were thunderstorms in the area, and although the sky eventually cleared completely, they still canceled my direct flight to Cape Town.  That was at 10 pm. and 100 people, including me, had to rebook (I was second in line but it still took me 1½ hours). Not only that, but we couldn’t get our luggage, which was loaded into the belly of the plane, for at least six hours (it took two days for me to recover my bag, which they had forced me to check even though it’s way smaller than a roller bag!).  Why an airplane can’t unload its bags and put them on the carousel is still a mystery to me. I rebooked for a flight to Capetown (direct) supposedly leaving tomorrow.

Fortunately, thanks to the grace of Ceiling Cat, my sister and her husband live only 20 minutes from Dulles Airport, and they provided me help and a refuge, especially given that I was basically abandoned by United Airlines and had no place to stay (they don’t give you vouchers for weather-related delays).  I spent two nights with Susan and Bob, and it was great to catch up with them, as I haven’t seen either of them in several years though we talk on the phone occasionally.

They drove me to the airport on Monday to retrieve my bags: but no dice. I was told they were somewhere in the airport but not yet “out,” but I should come back on the next day.   I had no spare clothes, but did have my toiletries and malaria pills and could wash up a bit.  On Tuesday I learned that on the day I was scheduled to fly out (two days later), thunderstorms were predicted AGAIN in Washington. That made me determined to get out of Dodge as fast as possible.  I decided to hie myself to the airport on Tuesday, and if my bag was there, to rebook to Capetown on the spot.

Mirabile dictu, my bag had finally arrived after two days of languishing somewhere in Dulles, and I grabbed it and ran to ticketing, waiting two hours in line to be rebooked.  Fortunately, there was an indirect flight to Cape Town that day, involving three legs:

a.) flying to Newark that evening
b.) catching a plane from Newark to Johannesburg (15 hours) after a 1.5-hour layover
c.) Flying from Joberg to Capetown late on Tuesday evening to meet my friends Marim and Rita (both biologists).

It was a nailbiter as EVERY flight was late, and I often had to run to make my connections, making me even sweatier and dirtier. BUT I MADE IT TO CAPETOWN LAST NIGHT, and South African Airlines even upgraded me to premium class as the plane was full.  I arrived last night, totally exhausted, dehydrated, and fell into a deep sleep immediately, waking up much refreshed after 7½ hours.

Now I’m writing this before I take a luxurious shower, shave, wash my hair, and put on clean clothes. What a luxury!

UPDATE:  Now I’m rested, showered, shaved, scrubbed, and breakfasted, and I feel like a new man.

And as soon as I’m ready, Martim and Rita taking me around the scenic Cederburg Mountains area of SW South Africa (see also here) for a four-day sightseeing and field trip. We will finally see the famous fynbos local vegetation, as well as ancient rock art of the San People (formerly called Bushmen).

As I said previously, the fynbos, now a World Heritage Site, is by far the smallest of the six”floral kingdoms” in the world, with a huge number of exotic and endemic plants seen nowhere else. And the mountains are supposed to be lovely.

Here’s a quick summary of what Martim sent me about our trip. I wouldn’t have been able to do this if I arrived Friday, but now it’s feasible. Here’s the itinerary from Martim:

I opted to not be overambitious regarding trip distances – so the aim is to both get to see a bit of the Karoo landscape (the semi-arid habitat that occupies almost 2/3 of South Africa) and of the mountain landscape of the Cederberg – those mountains I am deeply attached to. The mountains have both Karoo and fynbos (Mediterranean) vegetation. Day 1, we will head to the Karoo, and have something to eat at a ‘padstal’ (= farm stall) in the Karoo (Tankwa padstal). We will sleep at a farm nearby – Hartnekskloof. Day 2, we will head to the Cerderberg, passing by San paintings (Stadsaal and Truitjieskraal), and will stay in Driehoek for two nights (my base in the area). They have a small but very good wine production (their vines are those grown at the highest elevation in South Africa). Day 3 – we can hike straight away from where we are. Day 4 – return to Cape Town. Here’s the map of our itinerary made by Martim: We arrive back here the evening of the 10th, and then Martim has said he would show me some of the sights of Cape Town until I leave for Kruger on the 13th. Those include a trip to Robben Island,  another World Heritage Site, and the island gaol where Nelson Mandela spent 18 of his 27 years of imprisonment before he was freed, won the Nobel Peace Prize, and became President of South Africa. Robben is about 7 km from Capetown, and here’s a photo from Wikipedia. The island has been used to incarcerate political prisoners from the late seventeenth century until apartheid ended in 1996. In the background is Capetown and Table Mountain. South African Tourism from South Africa, CC BY 2.0, via Wikimedia Commons

There is also a new species of penguin for me to see, the African penguin  (Spheniscus demersus), which has a colony near where I’m staying.  It’s endemic to southern South Africa.  And there’s also Table Mountain, which rises high to the north of Cape Town, affording a terrific view.

Because I was late arriving, I extended my stay here for about a week so that I could see more of this lovely town, and then another local botanist, Jeremy, has offered to show me more plants and also take me out to eat and sample the wines of this area, which are famous.

I’m flying up to the Kruger area on Aug. 13, there to see the animals (and Ozy the warthog) and meet my friend Rosemary, who has kindly helped me arrange the northern part of my trip). I’ll stay a few days in a fancy safari lodge (my one nod to luxury), take a two-day trip to the Blyde River Canyon, and then spend several days driving around Kruger Park with Rosemary and a guide, staying in local huts and looking at wildlife, including the famous Southern ground hornbill, Bucorvus leadbeateri.

I return to Cape Town on Aug. 31 and will spend another week here, and to soak up more of the area.

I see from the news that Kamala Harris has picked a VP that is not Shapiro: Governor Tim Walz of Minnesota, and I have no idea whether that’s a canny choice. But I feel very far away from politics and the mishigas that is America now, and I’m grateful for that.

I will be back in Cape Town, hopefully with some good photos, in a few days, and I may be able to post them on the way. But have no fear, there will be pictures.

Stay sane!

Primordial black holes are thought to have formed early in the evolution of the universe. None have been discovered yet but if they do exist and they may be plentiful, drifting almost invisibly through the cosmos, then they might account for dark matter. One possible way to search for them is to see the results of their meals and a bizarre new theory suggests low mass black holes could be captured by neutron stars and become trapped inside, devouring them from within. If these strange objects existed then it would make neutron stars less common in locations where black holes would proliferate as observed around Galactic centre.

Black holes are fascinating objects. Some are formed when supermassive stars die, others (which are theoretical only at this stage) may have formed out of regions of higher density when the universe was young. It is possible they may account for a portion of, or maybe even all of the dark matter that makes up about 27% of the mass-energy content of the universe. Their discovery would certainly help to explain some of the mysteries surrounding dark matter but would also help to explain other observations to; microlensing events, correlations in the X-ray and cosmic infrared background fluctuations and mass, spin and coalescence rates for black holes found by LIGO/Virgo.

LIGO Observatory

In the paper published by Roberto Caiozzo, Gianfranco Bertone and Florian Kuhnel they explore the abundance of sub-stellar mass primordial black holes. They use modern analysis techniques and explore the possibility that the primordial black holes could be captured by neutron stars and sink to its core. Previous studies into this possibility have been undertaken most notably and most recently by Y. G ?enolini, P. D. Serpico, and P. Tinyakov in their paper “Revisiting primordial black hole capture into neutron stars.

The attention of Caiozzo and team focussed upon the innermost parsec of the Milky Way galaxy, the Galactic centre. They chose this location to study neutron star captured primordial black holes due to the expected high density of dark matter and the predicted population of pulsars. I should add here that most neutron stars are seen as pulsars. Pulsars are just neutron stars that rotate fast and we see them as producing pulses of radiation at short intervals often between milliseconds and seconds. It’s thought they should exist in their thousands however to date, hardly any have been found within the innermost region. It’s not known why there are so few however the team postulate that it may be due to disruption by the black holes. 

This image shows a section of the side view of the Milky Way as measured by ESA’s Gaia satellite. The dark band consists of gas and dust, which dims the light from the embedded stars. The Galactic Centre of the Milky Way is indicated on the right of the image, shining brightly below the dark zone. The box to the left of the middle marks the location of the “Maggie” filament. It shows the distribution of atomic hydrogen. The colours indicate different velocities of the gas. Credit: ESA/Gaia/DPAC, CC BY-SA 3.0 IGO & T. Müller/J. Syed/MPIA

Millisecond pulsars (those who spin rate is among the highest) would be an excellent choice for study. They are easy to locate and due to spectroscopic observations, they are thought to exist in large populations in the Galactic bulge, likely also close to Galactic centre. Previous predictions suggest there may be 67 long lived neutron star – X-ray binaries in the innermost region of the centre and these have been shown to be the progenitor of millisecond pulsars. It is therefore reasonable to assume a good population in the Galactic centre. 

The rate of capture of primordial black holes by neutron stars in the Galactic centre is the goal of the paper with existing calculations being revisited to produce a more realistic forecast. The team goes one step further though and look at the likelihood of the collapse of a neutron star given the disruption of a primordial black hole.  The team find however that, having improved all previous models, that the capture of the primordial black holes cannot explain why there are so few missing pulsars / neutron stars around Galactic centre. The disruption of neutron stars and pulsars is simply not likely to occur within their projected lifetime. 

Source : Revisiting Primordial Black Hole Capture by Neutron Stars

The post How a Black Hole Could Eat a Neutron Star from the Inside Out appeared first on Universe Today.

While staying at my sister and brother-in-law’s house near Dulles Airport, I encountered a few things of interest. The first is an arrival lunch at Willard’s BBQ near Dulles, and it was crowded, understandable in view of how good the BBQ was, especially for this area. Here’s my lunch of “burnt beef ends” (hard to find, a mixture of crunchy and juicy parts from brisket), along with two “vegetables” (mac and cheese and a fantastic potato salad), BBQ sauce (not needed) cornbread and, of course, sweet iced tea. I’d recommend this place if you are in the area.

And I had a look at the Virginia History textbook that my brother-in-law had when he was about 13.  He remembered it as having grossly distorted the horrors of slavery, which it did in a big way.

My sister found a copy of the book online, and I was appalled to see how slavery was described: as a great benefit to slaves, who got vocational education and had kindly masters and good working conditions. It was disgusting. Have a look at how, as kids, we were taught about slavery in Virginia.

The book:

An arriving enslaved person with his family, all decked out in fancy clothes and greeting his new “master” with glee. The family, too, is all happy and spiffy. The reality, of course, was far different, with slave families packed into the holds of the ships, with those who survived sold off soon after being kidnapped from Africa to the U.S., and families often being separated.

Part of the propaganda; read it!

Horses that are bred to race seem to perform better on the course if they had a diverse gut microbiome as foals

Meanwhile, in Dobrzyn, Hili plays the peacemaker:

Hili: Let’s not quarrel. A: But we do not quarrel. Hili: I know, but calls for unity are in fashion again

 

Hili: Nie kłóćmy się.
Ja: Przecież się nie kłócimy.
Hili: Wiem, ale wezwania do jedności znowu są modne.

 

Passenger planes and private jets that fly higher can create longer-lasting contrails, meaning their contribution to global warming has been underestimated

Eight Australian sea lions were fitted with cameras and trackers to capture unprecedented insights into their behaviour and the marine habitats where they hunt

To help protect drivers and machine operators from the dangers of drifting off, engineers have created prototype earbuds that can detect the signs of drowsiness in the brain. In a new study, the researchers show that their Ear EEG platform is sensitive enough to detect alpha waves, a pattern of brain activity that increases when you close your eyes or start to fall asleep.

Establishing communication with an alien intelligence is one of the news items I, and I’m sure many others, long to see. Since we have started the search for advanced civilisations we have tried numerous ways to detect their transmissions but to date, unsuccessfully. A new paper suggests quantum communication may be the ideal method for interstellar communication. It has many benefits but the challenge is that it would require a receiver over 100km across to pick up a signal. Alas they know we don’t have that tech yet!

The search for alien signals has been undertaken under the banner of the search for extraterrestrial intelligence or SETI for short. It began in 1960 when Frank Drake commenced the first search. It was of course not fruitful but since then, large radio telescopes have been used to undertake searches. There have been many projects but of particular interest has been Project Breakthrough. It has used advanced technology and international collaborations but still there has been no success. 

Frank Drake writing his famous equation on a white board. Credit: SETI.org

To be able to effectively search for alien signals its imperative to fully understand the nature of communication. A quest that started back in 1948 with the development of the modern theory of classical communication. In 1959 it was proposed that human technology was available to send or receive interstellar classical communication which simply requires a message, someone to send it and someone to receive it. 

Over the years that followed communication theories developed and quantum information theory emerged. It explores how quantum mechanics has an affect on the storage of and transmission of information. At the centre of the theory is the quantum bit or qubit which can exist in a number of states all at once due to the phenomenon of superposition. In classical information theory, bits of information are either 0 or 1 but in quantum theory they can be any infinite number of combinations with certain probabilities until measured. At that point, the wave function collapses to one of the definite states.

Another key element of quantum theory is entanglement where two or more particles are interconnected so that the state of one is related to the state of the other no matter how far apart they are. With qubits linked in this way data processing can be far faster than in classical model and more secure too. The paper authored by Latham Boyle from the University of Edinburgh suggests that it may be possible to send or receive information between the stars using quantum communications. A previous study by Arjun Berera proposed photon qubits could be used to transmit information over interstellar and even possibly intergalactic distances without loss of coherence. 

The concept of quantum coherence describes the ability to maintain the specific quantum state but this alone is not enough for communication. The communication channel must also have sufficient capacity. In addition, specific wavelengths must be used (or avoided for example wavelengths less than 26.5 cm to avoid issues with the cosmic microwave background.) To facilitate this, radio telescopes with a diameter of 100 km must be used. Currently we don’t have the capability to build such instruments and this may explain why, in such a large and old universe, we still haven’t detected any aliens yet! We may simply have to wait until we can build such instruments before aliens can communicate with us.

Source : On Interstellar Quantum Communication and the Fermi Paradox

The post If Advanced Civilizations Using Quantum Communications, Is That Why We’ve Never Seen Them? appeared first on Universe Today.

To address the problem of AIs generating inaccurate information, a team of ethicists says there should be legal obligations for companies to reduce the risk of errors, but there are doubts about whether it would work

A seismic shift occurred in astronomy during the Scientific Revolution, beginning with 16th-century polymath Copernicus and his proposal that the Earth revolved around the Sun. By the 17th century, famed engineer and astronomer Galileo Galilei refined Copernicus’ heliocentric model using observations made with telescopes he built himself. However, it was not until Kepler’s observations that the planets followed elliptical orbits around the Sun (rather than circular orbits) that astronomical models matched observations of the heavens completely.

As it turns out, this very quirk of orbital mechanics may be essential to the emergence of life on planets like Earth. That was the hypothesis put forth in a recent study by a team of astronomers led by the University of Leeds. According to their work, orbital eccentricity (how much a planet’s orbit deviates from a circle) can influence a planet’s climate response, which could have a profound effect on its potential habitability. These findings could be significant for exoplanet researchers as they continue to search for Earth-like planets that could support life.

The team was led by Binghan Liu, a PhD Student in the School of Physics and Astronomy at the University of Leeds, who conducted the research as part of his thesis. He was joined by Daniel R. Marsh, the Priestley Chair in Comparative Planetary Atmospheres (and Liu’s thesis advisor), and other colleagues from Leeds and the Institute of Astronomy at the University of Cambridge. Their paper, “Eccentric orbits may enhance the habitability of Earth-like exoplanets,” was recently published in the Monthly Notices of the Royal Astronomical Society.

The idea of circular orbits has deep roots in Western astronomy, going all the way back to Classical Antiquity. Some examples include Plato and Aristotle, who argued that the then-known celestial bodies (the Moon, Mercury, Venus, the Sun, Mars, Jupiter, and Saturn) were perfect spheres that orbited Earth in concentric circles. This belief endured well into the Scientific Revolution, with both Copernicus and Galileo arguing that the then-known planets (Mercury, Venus, the Earth and the Moon, Mars, Jupiter, and Saturn) orbited the Sun in concentric circles.

It was not until Johannes Kepler introduced the concept of elliptical orbits that scientists could match their astronomical models to the observed motions of the planets. Since then, scientists have learned a great deal about orbital parameters – such as semi-major axis (a), eccentricity (e), axial tilt (?), inclination (i), and periapsis – and how they can influence a planet’s climate over time. These parameters have also become very important for exoplanet studies, as they are vital to determining if a planet could be “potentially habitable.”

For their study, Liu and his colleagues used the Whole Atmosphere Community Climate Model (WACCM6), a high-top interactive Earth-system model capable of simulating conditions on Earth (from the oceans to the upper atmosphere) to simulate Earth-like exoplanets with two different orbital parameters. For one set, they assigned circular orbits (e = 0), while the others were assigned highly eccentric orbits (e = 0.4) – far greater than Earth’s eccentricity (0.016). They were also assigned zero obliquity (? = 0) and a fixed level of annual solar irradiance (aka. annual mean insolation).

After running 30 simulation years for each case, they examined how both groups of exoplanets behaved regarding their climate response. This included latitudinal and seasonal variations in their hydrological cycle (sea ice, land snow, and clouds) and land habitability metrics like surface temperature and precipitation. As they indicated in their paper, exoplanets within the highly eccentric orbit group had 25% more habitable land area for more than 80% of their orbit, with an average increase of 7% for their entire orbital cycle.

Artist’s illustration of Proxima Centauri b. ESO/M. Kornmesser

Naturally, there were some caveats and addendums that they were sure to include:

“It is important to note that the habitability of land depends on the chosen metric and the duration of time during which the conditions are met for a specific metric. We conclude that, under the same annual mean stellar flux, an Earth-analogue planet with zero-obliquity in a highly eccentric orbit around a Sun-like star may have enhanced land habitability compared to its circular counterpart.”

In other words, the simulations are based on planets with far more eccentric orbits than Earth and are not subject to the same changes in obliquity, which also profoundly impact Earth’s climate (i.e., glacial and inter-glacial periods). Nevertheless, their study demonstrates that planets with eccentric orbits are more likely to be habitable than those with circular orbits that experience little in the way of seasonal variations throughout the year. These results could have significant implications for exoplanet studies and the search for habitable worlds beyond the Solar System.

In addition, they note how astronomers will benefit from next-generation observatories that will be capable of spotting Earth-like exoplanets with eccentric orbits in the near future:

“The detection of highly eccentric terrestrial exoplanets is low due to the limitation of the current observation techniques, which are biased towards close-in and thus, tidally locked exoplanets in circular orbits. However, with the upcoming ground and space telescope missions such as PLATO, ELT, and HWO, more highly eccentric Earth-like rocky exoplanets may be revealed and characterized. Understanding the potential climate outcomes and habitability of highly eccentric rocky exoplanets remains a challenging task.”

Further Reading: MNRAS

The post Elliptical Orbits Could be Essential to the Habitability of Rocky Planets appeared first on Universe Today.

Nutrient-rich "dark earth" soil may store an amount of carbon nearly equivalent to annual CO2 emissions in the US, a finding that suggests the Amazon sequesters far more carbon than previously known

A planet orbiting extremely close to a white dwarf may have formed inside its star – this could be the origin of some of the most promising worlds beyond our solar system to search for life

Researchers are using mayonnaise to study and address the stability challenges of nuclear fusion by examining the phases of Rayleigh-Taylor instability. Their innovative approach aims to inform the design of more stable fusion capsules, contributing to the global effort to harness clean fusion energy. Their most recent paper explores the critical transitions between elastic and plastic phases in these conditions.

The world is going to need a lot of weird metals in the coming years, according to chemistry professor. But he isn't talking about lithium, cobalt or even beryllium. He's interested in dysprosium, which is so hidden in the periodic table that you'd be forgiven for thinking he made it up.

Researchers found that how well light-converting molecules stack together in a solid is important for how well they convert light into electric current. A rigid molecule that stacked well showed excellent electricity generation in an organic solar cell and photocatalyst, easily outperforming a similar flexible molecule that did not stack well. This new way of improving the design of molecules could be used to pioneer the next generation of light-converting devices.