https://www.facebook.com/profile.php?id=100089886166206

Flower world, Улица Каткова, Uzhhorod (2025)

13/02/2023

The global collaboration that delivered us not one but two pictures of supermassive black holes has now peered into one of the brightest lights in the Universe.

The Event Horizon Telescope (EHT), a telescope array comprising radio antennae around the world, studied a distant quasar named NRAO 530, whose light has traveled for 7.5 billion years to reach us.

The resulting data show us the quasar's engine in incredible detail and will, astronomers say, help us understand the complex physics of these incredible objects, and how they generate such blazing light.

Quasars – a term that's short for "quasi-stellar radio sources" – are a type of galaxy thought to be powered by a very active supermassive black hole at the center. That means that the black hole is surrounded by material that is falling onto it at a furious rate.

Black holes themselves emit no light, but the material around an active black hole does. Gravity and friction cause the material to heat up and blaze as it circles the black hole like water down a drain. But that's not all.

Not all the material falls onto the black hole. Some of it is funneled and accelerated along magnetic field lines just outside the event horizon – the "point of no return", beyond which not even light can reach escape velocity.

When this material reaches the poles, it is launched into space as powerful jets of plasma, traveling at speeds a significant percentage of the speed of light, referred to as relativistic speed. These thin collimated jets also shine brightly… but we don't fully understand how they are created and powered, and the role played by magnetic fields.

Enter the EHT. It's not one individual instrument or array, but a collaboration of radio telescope facilities around the world that combine to effectively form an Earth-sized radio telescope, kind of like an astronomy Voltron.

This telescope is a powerful thing. In 2019, it gave humanity our first ever image of the event horizon of a black hole, the heart of a galaxy named M87 55 million light-years away. Then, last year, it delivered an image of the supermassive black hole at the center of our own Milky Way galaxy, Sagittarius A*.

Both images were years in the making. The observations of NRAO 530 actually took place in April 2017; the international team used it as a calibration target for taking images of Sgr A*. This quasar is a popular calibration target for the center of the Milky Way, since the two objects appear pretty close together in the sky.

It's those observations that a team – led by astronomers Svetlana Jorstad of Boston University and Maciek Wielgus of the Max Planck Institute for Radio Astronomy in Germany – have now used to peer into the heart of NRAO 530. Across such a vast distance in time and space, the researchers were able to see the heart of the quasar in unprecedented detail.

"The light that we see traveled towards the Earth for 7.5 billion years through the expanding Universe, but with the power of the EHT we see the details of the source structure on a scale as small as a single light-year," explains Wielgus.

NRAO 530 is a rare type of quasar known as an "optically violent variable" quasar, and is known to have a powerful, highly relativistic jet. It's also categorized as a blazar; that's a blazar that's oriented in such a way that the jet is pointed directly or almost directly at us.

Blazars pose no danger, but can be quite challenging to study, like peering down a linear laser beam.

The EHT images show a bright feature at the southern end of the jet; the researchers believe that this is the radio "core", the point at which the jet is launched at a specific wavelength of light. This core has two components, which can't be seen at longer wavelengths of light, but are clearly visible in the EHT observations.

From their observations, the team was able to determine the polarization of the light emitted from different parts of the structure. This refers to the orientation of the oscillations of the light, which can be affected by magnetic fields that it travels through.

This allowed the team to map the magnetic fields in the jet, finding evidence that the magnetic field has a helical structure.

"The outermost feature has a particularly high degree of linear polarization, suggestive of a very well ordered magnetic field," Jorstad says.

To date, NRAO 530 is the most distant object the EHT has studied, and the results show promise for future studies of distant objects, as well as more detailed studies of blazars and quasars.

13/02/2023

A Brazilian man has passed away from injuries he received last month when a concealed handgun he was wearing discharged near an operating MRI machine, shooting him in the abdomen.

The 40-year-old lawyer and vocal supporter of gun ownership is reported to have retained the weapon in spite of verbal and written requests to remove all metal objects prior to accompanying his mother into the scanning room.

Leandro Mathias de Novaes took his mother to the Laboratorio Cura in São Paulo, Brazil, for an MRI ( magnetic resonance imaging) scan on January 16.

Clinical staff are reported to have instructed both de Novaes and his mother to leave all metal items outside of the scanning room as a matter of standard procedure.

"We would like to emphasize that all accident prevention protocols were followed by the Cura team, as is customary in all units," a spokesperson for the facility told The Telegraph.

"Both the patient and his companion were properly instructed regarding the procedures for accessing the examination room and warned about the removal of any and all metallic objects."

The reason for this simple act is fairly straight-forward. To image a body, an MRI uses anywhere from 1.5 to 3.0 (and sometimes more) tesla of magnetism to force the protons in water molecules to point roughly the same direction.

A low-energy pulse of electromagnetism gives the particles a jiggle, which depending on the surrounding materials take varying amounts of time to return to their starting point. This contrast in proton wiggles is then interpreted to provide a detailed picture of your insides.

To give some idea of just how strong that magnetic field is, a fridge magnet is in the range of a few thousandths of a tesla. Some powerful rare-earth magnets can be around a single tesla in strength.

So 3 to 7 tesla isn't Earth-shaking. But it is plenty enough for large ferromagnetic items – those made of material that react relatively uniformly in a strong magnetic field – to be given a good pull.

A freak accident in 2001 caused fatal head injuries in a child when an MRI dislodged a metal oxygen tank from across the room.

In cases of smaller items, as with jewelry for example, the strong magnetic field could create an electric current in the material that potentially conducts enough heat to deliver a nasty localized burn.

Exactly what happened in de Novaes's case might never be known. Tucked away hidden in his waistband, the gun fired when the machine was activated, delivering a wound that would tragically take his life after several weeks at the São Luiz Morumbi Hospital.

As an advocate for gun ownership with thousands of followers on his social media accounts, de Novaes was clearly no stranger when it came to handling a firearm. According to police records, he was licensed to carry it, and the weapon was registered.

Whether it was an issue of complacency or forgetfulness isn't clear, but the incident serves as a tragic reminder of the fact that MRIs and guns simply don't mix – and not the first either.

A 2002 article in the American Journal of Roentgenology recounts an incident of an off-duty police officer attending an outpatient imaging center in New York State, during which a miscommunication led to the patient taking his firearm into the scanning room.

While placing the gun on top of a cabinet about a meter (3 feet) from the machine, the weapon was pulled from his grasp into the scanner, where it discharged into a wall.

Meanwhile, in 2013, an on-duty officer's handgun was pulled from his hand while investigating a late-night report of a burglary at an Illinois MRI clinic, with the firearm remaining stuck to the machine.

In 2018, a man received leg injuries in a Long Island clinic when a handgun in his pocket fired on entering an MRI scanning room.

Though short, this list of dangerous MRI episodes could grow as gun ownership rises in the US, with the possibility of more injuries or even deaths. Several hundred people die each year in the US following the unintentional use of a firearm.

Short of using metal scanners on patients prior to entering an MRI, there is little medical staff can do but tap the sign. 'All metal' means guns too, and not following those rules can sadly have deadly consequences.

11/02/2023

It can be tempting to think that the recent wildfire disasters in communities across the West were unlucky, one-off events, but evidence is accumulating that points to a trend.

In a new study, we found a 246 percent increase in the number of homes and structures destroyed by wildfires in the contiguous Western US between the past two decades, 1999-2009 and 2010-2020.

This trend is strongly influenced by major fires in 2017, 2018 and 2020, including destructive fires in Paradise and Santa Rosa, California, and in Colorado, Oregon, and Washington.

In fact, in nearly every Western state, more homes and buildings were destroyed by wildfire over the past decade than the decade before, revealing increasing vulnerability to wildfire disasters.

What explains the increasing home and structure loss?

Surprisingly, it's not just the trend of burning more area, or simply more homes being built where fires historically burned. While those trends play a role, increasing home and structure loss is outpacing both.

As fire scientists, we have spent decades studying the causes and impacts of wildfires, in both the recent and more distant past. It's clear that the current wildfire crisis in the Western US has human fingerprints all over it.

In our view, now more than ever, humanity needs to understand its role.

Wildfires are becoming more destructive
From 1999 to 2009, an average of 1.3 structures were destroyed for every 4 square miles burned (1,000 hectares, or 10 square kilometers). This average more than doubled to 3.4 during the following decade, 2010-2020.

Nearly every Western state lost more structures for every square mile burned, with the exception of New Mexico and Arizona.

Graph showing trends in structure losses due to wildfires
Adapted from Higuera, et al., PNAS Nexus 2023, CC BY
Humans increasingly cause destructive wildfires
Given the damage from the wildfires you hear about on the news, you may be surprised to learn that 88 percent of wildfires in the West over the past two decades destroyed zero structures. This is, in part, because the majority of area burned (65 percent) is still due to lightning-ignited wildfires, often in remote areas.

But among wildfires that do burn homes or other structures, humans play a disproportionate role – 76 percent over the past two decades were started by unplanned human-related ignitions, including backyard burning, downed power lines, and campfires. The area burned from human-related ignitions rose 51 percent between 1999-2009 and 2010-2020.

This is important because wildfires started by human activities or infrastructure have vastly different impacts and characteristics that can make them more destructive.

Unplanned human ignitions typically occur near buildings and tend to burn in grasses that dry out easily and burn quickly. And people have built more homes and buildings in areas surrounded by flammable vegetation, with the number of structures up by 40 percent over the past two decades across the West, with every state contributing to the trend.

Human-caused wildfires also expand the fire season beyond the summer months when lightning is most common, and they are particularly destructive during late summer and fall when they overlap with periods of high winds.

As a result, of all the wildfires that destroy structures in the West, human-caused events typically destroy over 10 times more structures for every square mile burned, compared to lighting-caused events.

Maps of where wildfires have burned in 21st century in Western US
Adapted from Higuera, et al., PNAS Nexus 2023, CC BY
The December 2021 Marshall Fire that destroyed more than 1,000 homes and buildings in the suburbs near Boulder, Colorado, fit this pattern to a T. Powerful winds sent the fire racing through neighborhoods and vegetation that was unusually dry for late December.

As human-caused climate change leaves vegetation more flammable later into each year, the consequences of accidental ignitions are magnified.

Putting out all fires isn't the answer
This might make it easy to think that if we just put out all fires, we would be safer. Yet a focus on stopping wildfires at all costs is, in part, what got the West into its current predicament. Fire risks just accumulate for the future.

The amount of flammable vegetation has increased in many regions because of an absence of burning due to emphasizing fire suppression, preventing Indigenous fire stewardship and a fear of fire in any context, well exemplified by Smokey Bear.

Putting out every fire quickly removes the positive, beneficial effects of fires in Western ecosystems, including clearing away hazardous fuels so future fires burn less intensely.

How to reduce risk of destructive wildfires
The good news is that people have the ability to affect change, now. Preventing wildfire disasters necessarily means minimizing unplanned human-related ignitions. And it requires more than Smokey Bear's message that "only you can prevent forest fires." Infrastructure, like downed power lines, has caused some of the deadliest wildfires in recent years.

Reducing wildfire risks across communities, states, and regions requires transformative changes beyond individual actions. We need innovative approaches and perspectives for how we build, provide power, and manage lands, as well as mechanisms that ensure changes work across socioeconomic levels.

08/02/2023

The genetic make-up of the iconic Australian black swan (Cygnus atratus) leaves it extremely vulnerable to viruses such as avian flu, research from the University of Queensland reports.

The threat is thought to be so severe that it could wipe out the species entirely.

The discovery comes after the distinctive bird's genome was sequenced for the first time in 2021.

Ordinarily, this achievement would be something to celebrate from a scientific perspective – but a comparison with closely-related northern hemisphere white swans has revealed that certain key immune genes are missing from its DNA.

That's likely to be, at least partly, down to the way that the black swan is isolated geographically. These animals haven't had the same exposure to pathogens that are found outside of southeast and southwest Australia, the areas where it primarily lives and breeds.

"[B]lack swans are extremely sensitive to highly pathogenic avian influenza – HPAI which is often referred to as bird flu - and can die from it within three days," says microbiologist Kirsty Short from the University of Queensland in Australia.

"Our data suggests that the immune system of the black swan is such that, should any avian viral infection become established in its native habitat, their survival would be in peril."

The team used powerful computer software to compare the genes of the black swan with the closely-related mute swan (Cygnus olor), found in the Northern hemisphere. Tens of thousands of genes were compared in total in the search for differences.

It was discovered that a class of proteins in the toll-like receptor 7 (TLR7) family were not being activated as they should. These parts of the genome have been associated with protecting against bird flu and other pathogens.

In other words, the gene for guarding against the bird flu virus is there, it's just not being switched on when needed – and that puts the black swan under threat.

The team also identified an unregulated inflammatory response to infection that could be dangerous.

"We currently don't have HPAI in Australia, but it has spread from Asia to North America, Europe, North Africa, and South America. When it was introduced to new locations, such as Chile and Peru, thousands of wild seabirds perished," says Short.

During the course of their research, the study authors also identified another gene – SLC45A2 – that may be responsible for black swans being black rather than white.

In fact, as mutations of this gene leads to loss of pigment – the same gene has previously been linked to albinism in humans – it suggests the white swan is the newer variant, and that the ancestral swans of both species were black.

The good news is that knowing more about the vulnerability of these birds is going to help in efforts to protect them. Either through selective breeding, or through immunotherapy treatments, this TLR7 gap in the immune defenses could be filled.

Right now, the black swan is one of the species that conservationists are least worried about, with a population worldwide of up to a million. Those numbers could drastically change in a short period of time, however.

"The risk to one of Australia's most unique and beautiful birds is very real, and we need to be prepared if we hope to protect it," says Short.

06/02/2023

Jupiter isn't alone along its orbital path around the Sun. Two giant swarms of asteroids have been snared in the gravitational interaction between the gas giant and our star, leading and trailing Jupiter as it treads its cosmic measure.

Between these swarms, known collectively as trojans, we've identified more than 12,000 asteroids to date, but there's a curious mystery that has baffled scientists: The leading swarm, known as the Greeks or L4 swarm, has significantly more asteroids than the trailing Trojans or L5, even though both groups seem equally stable.

Now a team of scientists has an answer: a change in Jupiter's distance from the Sun in the early days of the Solar System. Specifically, moving from a closer proximity to its current orbit.

"We propose that an outward, in terms of distance to the Sun, fast migration of Jupiter can distort the configuration of the Trojan swarms, resulting in more stable orbits in the L4 swarm than in the L5 one," says astronomer Jian Li of Nanjing University in China.

"This mechanism, which temporarily induced different evolution paths for the two asteroid groups that share the orbit of Jupiter, provides a new and natural explanation for the unbiased observation, that the L4 asteroids are about 1.6 times more than the asteroids in the L5 swarm."

L4 and L5 refer to Lagrange points, gravitationally stable points that occur during two-body interactions. Each two-body system has five Lagrange points, where the gravitational interaction between the two bodies balances with the centripetal force required for a small body to move with them.

Three of these points lie along the line connecting the two large bodies. The remaining two, L4 and L5, share the orbital path of the smaller of the two bodies, L4 leading and L5 trailing.

Jupiter's Greeks and Trojans, according to decades of research, should be similarly numerous. The two populations have almost identical properties related to their stability and survivability, yet the Greeks far outnumber the Trojans. To figure out why, Li and his colleagues decided to model Jupiter's early evolution based on something called early giant-planet instability.

This theory suggests that Jupiter formed at a different location from its current position but was booted out by a gravitational disruption from another planetary body early in the Solar System's history.

The Grand Tack hypothesis, which could resolve several problems with the Solar System, suggests that Jupiter moved inwards towards the Sun and then moved back out again to its current distance.

According to the team's model, the asymmetry in the trojan population can be replicated during a rapid outward migration, during which Trojans are lost. Greeks, on the other hand, are lost during the inward migration. The team's model suggests that Jupiter migrated outwards more than inwards, resulting in a higher population of Greeks.

This is a different scenario from a 2019 study that found the asymmetry was the result solely of an inward migration, but it lines up better with the Grand Tack hypothesis.

The model, as it stands, is a pretty interesting starting point, but the researchers note that it is relatively rough. Future research could work on producing a more finely detailed model to discover if the number, order, or length of migrations is relevant to the number of trojans.

The current work didn't take into account the potential effects of Saturn, Uranus, or Neptune, either. For a more accurate result, these bodies could be included.

And identifying more trojans will give a more accurate description of the population of these objects, which will also help refine future analyses, the researchers say. But the line of inquiry looks promising.

"The characteristics of the current Solar System hold as-yet unsolved mysteries into its formation and early evolution," says astronomer Nikolaos Georgakarakos of New York University Abu Dhabi in the United Arab Emirates.

"The ability to successfully simulate an event from an early stage of the Solar System's development and apply those results to modern-day questions can also be a key tool as astrophysicists, and other researchers work to learn more about the dawn of our world."

03/02/2023

One of the most hotly debated questions in the history of Neanderthal research has been whether they created art.

In the past few years, the consensus has become that they did, sometimes. But, like their relations at either end of the hominoid evolutionary tree, chimpanzees and Homo sapiens, Neanderthals' behavior varied culturally from group to group and over time.

Their art was perhaps more abstract than the stereotypical figure and animal cave paintings Homo Sapiens made after the Neanderthals disappeared about 30,000 years ago. But archaeologists are beginning to appreciate how creative Neanderthal art was in its own right.

Homo sapiens are thought to have evolved in Africa from at least 315,000 years ago. Neanderthal populations in Europe have been traced back at least 400,000 years.

As early as 250,000 years ago, Neanderthals were mixing minerals such as hematite (ochre) and manganese with fluids to make red and black paints – presumably to decorate the body and clothing.

It's human nature
Research by Paleolithic archaeologists in the 1990s radically changed the common view of Neanderthals as dullards. We now know that, far from trying to keep up with the Homo sapiens, they had a nuanced behavioral evolution of their own. Their large brains earned their evolutionary keep.

We know from finding remains in underground caves, including footprints and evidence of tool use and pigments in places where Neanderthals had no obvious reason to be that they appear to have been inquisitive about their world.

Why were they straying from the world of light into the dangerous depths where there was no food or drinkable water? We can't say for sure, but as this sometimes involved creating art on cave walls it was probably meaningful in some way rather than just exploration.

Neanderthals lived in small, close-knit groups that were highly nomadic. When they travelled, they carried embers with them to light small fires at the rock shelters and river banks where they camped. They used tools to whittle their spears and butcher carcasses.

We should think of them as family groups, held together by constant negotiations and competition between people. Although organized into small groups it was really a world of individuals.

The evolution of Neanderthals' visual culture over time suggests their social structures were changing. They increasingly used pigments and ornaments to decorate their bodies.

As I elaborate in my book, Homo Sapiens Rediscovered, Neanderthals adorned their bodies perhaps as competition for group leadership became more sophisticated. Colors and ornaments conveyed messages about strength and power, helping individuals convince their contemporaries of their strength and suitability to lead.

Red pigment washed into the concavities of a bright stalactite drapery in Ardales Cave
Red pigment washed into the concavities of a bright stalactite drapery in Ardales Cave. (Paul Pettitt and cave art dating team, Author provided)
Then, at least 65,000 years ago, Neanderthals used red pigments to paint marks on the walls of deep caves in Spain. In Ardales cave near to Malaga in southern Spain they colored the concave sections of bright white stalactites.

In Maltravieso cave in Extremadura, western Spain, they drew around their hands. And in La Pasiega cave in Cantabria in the north, one Neanderthal made a rectangle by pressing pigment-covered fingertips repeatedly to the wall.

Neanderthal hand stencils appear faintly on cave wall, identified by arrows.
One of several dozen hand stencils left in Maltravieso Cave. In the case of this hand the Neanderthal who left it would have had to lie on the floor as it was created on a ceiling barely 30 cm high. (Paul Pettitt and cave art dating team, Author provided)
We can't guess the specific meaning of these marks, but they suggest that Neanderthal people were becoming more imaginative.

Later still, about 50,000 years ago, came personal ornaments to accessorize the body. These were restricted to animal body parts – pendants made of carnivore teeth, shells and bits of bone. These necklaces were similar to those worn around the same time by Homo sapiens, probably reflecting a simple shared communication that each group could understand.

Did Neanderthal visual culture differ from that of Homo sapiens? I think it probably did, although not in sophistication. They were producing non-figurative art tens of millennia before the arrival of Homo sapiens in Europe, showing that they had independently created it.

But it differed. We have as yet no evidence that Neanderthals produced figurative art such as paintings of people or animals, which from at least 37,000 years ago was widely produced by the Homo sapiens groups that would eventually replace them in Eurasia.

Figurative art is not a badge of modernity, nor the lack of it an indication of primitiveness. Neanderthals used visual culture in a different way to their successors. Their colors and ornaments strengthened messages about each other through their own bodies rather than depictions of things.

Man standing beneath cave roof with hands raised to highlight the position of hand stencils in illuminated cave.
In many cases hand stencils were left on parts of cave walls and ceilings that were difficult to access, such as these in El Castillo cave, with Paul Pettitt showing the position of the hands. (Paul Pettitt and cave art dating team, Author provided)
It may be significant that our own species didn't produce images of animals or anything else until after the Neanderthals, Denisovans and other human groups had become extinct. Nobody had use for it in the biologically mixed Eurasia of 300,000 to 40,000 years ago.

But in Africa a variation on this theme was emerging. Our early ancestors were using their own pigments and non-figurative marks to begin referring to shared emblems of social groups such as repeated clusters of lines – specific patterns.

Their art appears to have been less about individuals and more about communities, using shared signs such as those engraved onto lumps of ochre in Blombos cave in South Africa, like tribal designs. Ethnicities were emerging, and groups – held together by social rules and conventions – would be the inheritors of Eurasia.

Flower world

13/02/2023

13/02/2023

11/02/2023

08/02/2023

06/02/2023

03/02/2023

Address

Telephone

Website

Alerts

Contact The Practice

Shortcuts

Share

Category