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What is the winter solstice and when does it occur?



You must have come across the term “winter solstice” by now. Whats Winter solstice and when happens?

When the sun rises in the southeast quarter of the horizon and at the end of its degree, that day is the day of the winter solstice. This event and its date both have the meaning of this name, and the winter solstice here means that the sun is in this path for a period that occurs and is fixed and does not shine in all its glory, and it seems that in the rest of the year to the situation. As usual, it is far away in the sky. Before it returns to its previous path, i.e., along the eastern horizon, it stops and slows down its movement.

What is Winter solstice

Everyone knows that winter happens in two phases on Earth – mid-year in the southern hemisphere and next year in the northern hemisphere. The winter sun moves in the southern part of the sky. Its path is short, and the daylight hours are few. Therefore, the winter solstice occurs on December 20 or 21 in the Gregorian calendar, which means the longest night and the shortest day of the year.

Read more : When did human succeeded in cooking with fire?

Seasons in countries north and south of the equator are opposite. But while opposite events are happening in the two hemispheres, the winter solstice occurs simultaneously, for everyone, anywhere on Earth.

The winter solstice, the longest night of the year, occurs on December 21 or 22 in the Northern Hemisphere and June 20 or 21 in the Southern Hemisphere.

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How have bees domesticated viruses?




How have bees domesticated viruses? Some insects have turned wild viruses into tiny bioweapons to protect and nurture their young.

How have bees domesticated viruses?

If you pierce the ovary of a species of honeyless bee called Microplitis demolitor, many viruses will come out and shine like iridescent blue toothpaste. This parasitic bee lays its eggs inside the cocoon worm, and the particles in their ovaries are domesticated viruses that have been adjusted to remain harmless in the bees’ bodies and serve their purposes.

The virus particles enter the cocoon worm through the bee sting along with the bee’s own eggs. The viruses then empty their contents into the cocoon’s cells and deliver genes that differ from those of normal viruses. These genes suppress the cocoon’s immune system and control its growth, making it a safe breeding ground for baby bees.

The insect world is full of parasitic wasp species that spend their infancy eating other living insects. For reasons that scientists do not fully understand, bees have repeatedly tamed disease-causing viruses and turned them into biological weapons. Currently, many examples of this have been described and new research has pointed to more examples. Nowadays, researchers are discovering the mechanism of this process by studying viruses in different stages of domestication.

Bee reproductive organs
The blue color of these reproductive organs of bees comes from the high number of viral particles. Microplitis demolitor bees produce domesticated virus particles in their ovaries (pictured above). Diachasmimorpha longicaudata bees may be in the early stages of domesticating a virus from the poxvirus family that replicates in their venom glands (bottom image).

A prominent example of a virus domesticated by honey bees includes a group called bracoviruses, which are thought to be derived from a virus that infected the honey bee or its host, the cocoon worm, about a hundred million years ago. That ancient virus inserted its DNA into the honey bee genome. Since then, this DNA has become part of the bee’s genome and passed on to subsequent generations.

Over time, bees diversified into new species and viruses diversified along with them. Bracoviruses are found in about 50,000 honeyless bee species, including M. demalitor. Other domesticated viruses originated from different wild viruses that entered the bee genome at different times.

Parasitic bees spend their infancy eating other living insects

Researchers are debating whether domesticated viruses should be called viruses at all. In an article published in 2020 in the Annual Review of Entomology, an ecologist from the University of Wageningen in the Netherlands, Marcel Dick, explains how domesticated viruses indirectly affect plants and other organisms. He says some people say they’re still viruses, others say they’ve merged with the bee and are therefore part of the bee.

As the bee-virus combination evolves, the virus genome spreads throughout the bee’s DNA. Some genes are lost, but a certain set of them remain that are essential for making the initial infectious virus particles. These pieces are located in different places in the bee genome, but they can still communicate with each other. “They’re still making products that work together to make virus particles,” says University of Georgia entomologist Michael Strand. “But instead of having a complete viral genome like the wild virus, the domesticated virus particles act as a delivery vehicle for the bee’s weapons.”

The weapons that bees use are very different. Some of them are proteins, while others are genes on small pieces of DNA. Most of them bear little resemblance to what is seen in bees or viruses, so it is not clear where they originated. They are also constantly changing and are in an evolutionary arms race with cocoon defenses or other measures.

In many cases, researchers have yet to discover what the genes and proteins do inside the bee host or prove that they function as weapons. But they have discovered some details. For example, M. demolitor bees use bracoviruses to deliver a gene called glc1.8 to the immune cells of moth larvae, which causes the infected immune cells to produce mucus that prevents them from attaching to the bees’ eggs. Other genes in M. demolitor bee bracoviruses cause immune cells to destroy themselves, while others prevent larvae from suffocating the parasite in melanin sheaths.

Bees maintain their control over viruses

Taming viruses can be dangerous. However, the wild relatives of domesticated viruses can be lethal, causing cells to produce virus particles and then burst them to release their contents. Some of them cause the body of insects to dissolve and turn them into sticky juice. In fact, even under domesticated conditions, sometimes specialized cells inside bees’ ovaries must burst to release viral particles. The bee must find a way to control that virus so that it does not infect and destroy the bee itself.

Parasitic bee larvaeCotesia glomerata wasps lay their eggs along with barcovirus particles in white butterfly larvae. Bracoviruses infect the cells of the cocooning worm so that the worm’s body cannot harm the developing bees. When the bee larva is ready, it leaves the cocoon and turns into a pupa. The cocoon worm makes a protective web over the bee pupa and protects them until they mature. The virus remains in the cocoon’s cells until the bee larvae emerge, so some researchers speculate that they may be responsible for the cocoon’s protective behavior.

How did bees evolve to be able to domesticate bees? More importantly, they have neutralized viruses. Virus particles cannot reproduce because they do not contain the genes that are critical for making new virus particles. They remain in the bee genome.

Bees also control where and when domesticated virus particles are produced. The reason for this is probably to reduce the risk of recalcitrance of the virus. Bracovirus particles are made only in one part of the female reproductive system and only for a limited time, and the key genes of the virus have been completely destroyed so that domesticated viruses cannot replicate their DNA. This loss is seen even in recently domesticated viruses, suggesting that this step is critical.

Any gene that is not useful for the bee gradually accumulates mutations. In bracoviruses, so much time has passed that unused genes are detectable. In recently domesticated viruses, residues are still detectable.

Discovery of mechanisms

It is not unusual to have a genome full of dead viruses. Viruses always jump into animal genomes. Even our DNA is full of remnants of viruses. However, only parasitic bees are known to have the ability to maintain a complete set of genes that work together to make viral particles.

Virus particles within the bee genome do not replicate because they do not contain the genes that are critical for making new virus particles.

Researchers are eager to understand how these relationships begin. For clues, some have turned to the tiny orange honey bee Diachasmimorpha longicaudata , which may be a poxvirus in the early stages of domestication. This poxvirus is not a true domesticated virus because its DNA was not introduced into the bee genome. Instead, the virus replicates inside the bee’s venom glands.

Like other virus-harvesting bees, the D. longicaudata bee injects virus particles into its host, which in this case is a fruit fly larva. Kaufman and Burke, along with Taylor Harrell, have shown that without poxviruses, most bee larvae die. But unlike fully domesticated viruses, this poxvirus replicates outside the bee and produces new virus particles in larval cells. The bee takes advantage of the poxvirus but does not completely control it.

Kelsey Kaufman, an entomologist at the University of Tennessee, says this poor control could be an indication of the type of virus the bees are starting with. Most domesticated viruses originate from a type of virus called nodiviruses, which can integrate into the bee genome more easily than poxviruses. But it is also possible that the bees have not had enough time yet. In fact, the association between bees and poxviruses is so new that it appears to exist in only one species of bee.

The virus is only found in certain tissues and only reproduces when the eggs are developing, which could mean that the bee has already developed defenses. Viruses also seem to be losing their ability to transmit without the help of bees. Kaufman has tried feeding flies many viruses and they didn’t seem to get infected that way.

parasitic beeDiachasmimorpha longicaudata wasps dig their stingers into the web to reach their host, the larva on that side. When they inject their eggs, they also introduce a type of poxvirus with the eggs into the larvae, which may be in the early stages of domestication.

Kaufman calls the poxvirus system exciting because little is known about how the domestication process of viruses begins. We cannot go back and see how this process begins. However, the new system can provide us with an insight into the beginning of this process. Although no one knows for sure why parasitic bees continue to domesticate viruses, researchers speculate that it has something to do with their lifestyle.

Internal parasites live inside their hosts, which are dangerous environments that they actively try to kill. From the bee’s point of view, viruses are like packages full of tools to solve this most catastrophic problem.

A study published in 2023 supports this idea. This research examined the genome of more than 120 species of honey bees, ants, and honey bees. The researchers examined these genomes for signs of the types of viruses that are susceptible to domestication. They inferred the presence of domesticated viruses by identifying viral genes that were functionally conserved over evolutionary time. Such conservation is expected if the genes help bees to survive or reproduce.

As expected, non-parasitic insects showed little evidence of having these domesticated viruses. The same was true for parasites that grow outside their hosts’ bodies where the host’s immune system cannot attack them. But in parasites that grow inside other insects, domesticated viruses seem to be much more common.

Julien Varaldi, a biologist at Claude Bernard Lyon 1 University in France and one of the authors of the study, says that there is a special connection between viruses and these internal parasites. This shows that viruses play an important role in the evolution of this lifestyle. With hundreds of thousands of bee species and countless strains of viruses, it’s highly likely that the two creatures could mate. In this situation, there are many opportunities for development.

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Discovery of new hydrothermal wells at a depth of 2.5 km in the ocean




hydrothermal wells

Scientists have managed to discover new active hydrothermal wells at a depth of 2,550 meters below the surface of the ocean, wells that emit water with a temperature of more than 300 degrees Celsius.

Discovery of new hydrothermal wells at a depth of 2.5 km in the ocean

Five active and new hydrothermal wells have been discovered in the Pacific Ocean at a depth of 2,550 meters on the seabed. These wells are places where superheated water erupts from the sea floor.

A hydrothermal vent is a crack on the surface of the earth, which geologically heats the surrounding waters.

Hydrothermal vents are often found in areas that are volcanically active, such as areas where tectonic plates are moving apart, ocean floors, and hot spots. The most famous hydrothermal system on land is probably Yellowstone National Park in America. Under the sea, hydrothermal vents are called black chimneys and can be found in most deep ocean waters.

The surroundings of hydrothermal wells are biologically more productive and are often home to complex communities that use chemicals dissolved in well fluids. Chemosynthetic activities form the base of the food chain and are used by organisms as diverse as large tube worms, bivalves, barnacles, and shrimp.

It is believed that there are active hydrothermal vents on Jupiter’s moon Europa and also on one of Saturn’s moons Enceladus. It is also believed that there were active hydrothermal vents on Mars in the past.

hydrothermal wells

It should be mentioned that these new hydrothermal wells were discovered by Sentry, which is an autonomous underwater probe, accompanied by Alvin, a manned submarine. These two technologies together accelerated the process of this research and exploration.

“By jointly operating these two advanced deep-sea submarines, we can make significant new discoveries about how the deep ocean floor is structured in some of the most inhospitable environments on Earth,” said Ross Parnell-Turner, a member of the operations team.

The team, led by Jill McDermott of Lehigh University, discovered these wells in a highly volcanic region in the eastern Pacific. These wells spit out fluids with a temperature of more than 300 degrees Celsius.

Read more: The discovery of a “lost world” belonging to a billion years ago

Supervolcanic region

These wells are formed due to the continuous separation of tectonic or tectonic plates in the East Pacific Rise, which is located in the wide volcanic mountain chain of the mid-ocean ridge. In this section, two tectonic plates are moving away from each other by approximately 11 cm per year.

Mid-ocean ridges are underwater mountain ranges formed by plate tectonics. The mid-ocean ridges are connected and form a global mid-ocean ridge system.

Thibaut Barriere, one of the senior scientists of this exploration from the University of Brest in France, says: The mid-ocean ridge accounts for more than 75% of all volcanic activity on our planet.

He, who is an expert in thermal measurements and modeling of hydrothermal wells, added: This area is filled with thousands of hot water springs in the deep sea like this, all of which remove 10% of the total internal heat of the earth.

We want to increase our understanding of how hydrothermal vents release heat and chemicals as they pass through the seafloor and affect the global ocean.

The researchers first sent Sentry to use its sensors to create high-resolution maps during the night. Maps of this robot were analyzed to show how humans travel to this location during the day. This process allowed them to collect first-hand data.

“The high-resolution maps that Sentry produces will allow us to identify new hydrothermal fields immediately after the robot returns to the deck,” McDermott said. Sentry gives us great targets for Alvin and the opportunity for multiple discoveries in one dive.

Finding extraterrestrial life

Wells rich in chemicals are known to support life around them, even in the darkest and deepest places on the sea floor. Studying these wells can provide valuable insights into the conditions they may support beyond Earth.

Saturn’s moon Enceladus is believed to have hydrothermal vents beneath its icy surface.

Additionally, understanding hydrothermal vents helps scientists understand the geophysical, chemical, and biological processes that shape our planet.

The study team aims to further investigate this hydrothermal activity and volcanoes along the eastern Pacific mid-ocean ridge in a subsequent mission that will also include the use of Sentry and Alvin.

It is worth mentioning that the Alvin probe has been involved in the discovery of several hydrothermal vents since 1977 and began its work by investigating an ocean ridge in the north of the Galapagos Islands.

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Climate change slows down the rotation of the earth!




Climate change slows down the rotation of the earth!
Researchers at the University of California, San Diego have written in a new paper that climate change significantly alters the Earth’s rotation and disrupts time.

Climate change slows down the rotation of the earth!

Climate change seems to be disrupting time.

According to the Washington Post, the melting of polar ice caps due to global warming affects the rotation of the Earth and can also affect accurate timekeeping.

The planet is not going to stop, nor is it going to speed up so much that everyone is launched into space, but timing is an exact science in a high-tech society. For this reason, humans were forced to invent the concept of “leap second” more than half a century ago by observing slight changes in the Earth’s rotation.

Climate change has now complicated these calculations. In just a few years it may be necessary to introduce a “negative leap second” into the calendar to bring the planet’s rotation into line with the Universally Coordinated Clock.

University of California, San Diego (UCSD) geophysicist Duncan Agnew said: Global warming actually measurably affects the rotation of the entire Earth. Things are happening that have not happened before.

The main problem with timing

Chronology has traditionally had an astronomical basis. The earth is a kind of clock. In simpler times, the planet made one complete revolution on its axis, and everyone called that a day.

However, technologists are looking for difficult levels of accuracy. Atomic clocks already tell us what time it is. The goal of people who want to do things exactly right is to make sure that atomic time is perfectly aligned with astronomical time. For example, GPS-equipped satellites must know exactly where the earth is below them and exactly what time it is in order to accurately get you from home to your destination.

But the earth does not rotate at a constant speed. Our planet is in a complex gravitational dance with the moon, sun, ocean tides, its atmosphere, and the motion of the solid inner core.

Agnew noted that the Earth’s core is not accessible for close inspection and is a bit like a black box. By drilling into certain areas of the sea floor, geophysicists can understand details about the planet’s interior. Last year, it was reported that scientists had detected changes in the Earth’s rotation that seemed to match the 70-year fluctuations in the core’s rotation.

When scientists try to describe what the Earth is doing at any given moment, they have to account for a lot of tilting and shaking.

Read More: Climate changes will continue for 50 thousand years

Earth is no longer slowing down. In fact, the Earth has sped up quite a bit, and not a single leap second has been added since the end of 2016.

تغییرات اقلیمی، سرعت چرخش زمین را کند می‌کنند!

Melting of the Antarctic and Greenland ice sheets transports the melt water towards the equator. This process increases the equatorial bulge of the planet. Meanwhile, land compressed by ice rises at the poles, making the Earth more spherical. National Institute of Standards and Technology (NIST) physicist Judah Levine, who was not involved in this research, said: These two changes in the shape of the planet have opposite effects on its rotation.

Agnew’s new paper says that although the core makes the planet spin faster, changes in the planet’s shape caused by warming climates slow it down. Without this effect, the overall acceleration of the planet’s rotation might require timers to enter a negative leap second at the end of 2026, Agnew wrote. Due to climate change, this may not be necessary until 2029.

This research was published in “Nature” magazine.

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