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What is a role of Saharan dust on hurricanes?
🌪🌧 Hurricanes, including tropical cyclone rainfall (TCR), are among the most destructive weather phenomena on Earth.
🌡💧Traditionally, sea surface temperature or humidity in the atmosphere were considered as the main factor controlling hurricane precipitation.
🏜❗️Now, scientists believe that Sahara dust plays a leading role on hurricane formation over the ocean, which affects weather in America.
ℹ️ Previous studies have found that Saharan dust transport may decline in the future and TCR could increase due to a climate change.
➡️⬅️According to a recent research, dust can however have competing effects on TCR.
✔️A dust particle can make ice clouds form more efficiently in the core of the hurricane, which can produce more precipitation.
✔️Dust can also block solar radiation and cool sea surface temperatures around a storm’s core, which weakens the TCR.
At high concentrations, dust shifts from boosting to suppressing rainfall.
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When and why was the Sahara green?
✅ Records from ocean sediment show that the Green Sahara happens repeatedly in Earth's history.
✅ Sometime between 11,000 and 5,000 years ago, after the last ice age ended, about 9 mln square kilometers (3.5 mln square miles) of the modern Sahara Desert was a green place with lakes, where animals like elephants, hippos and antelopes feasted on thriving grasses and shrubs.
✅ The Green Sahara, also known as the African Humid Period, was caused by the Earth's constantly changing orbital rotation around its axis, a pattern that repeats itself every 23,000 years, researchers believe.
✅ Right now, the Northern Hemisphere is closest to the sun during the winter months, and during the Green Sahara, the Northern Hemisphere was closest to the sun during the summer. This led to an increase in solar radiation, in other words, heat, heat in summer, and created a low pressure system that ushered moisture from the Atlantic Ocean into the desert.
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How does the brain store memories?
🧠 In the brain, the hippocampus region, crucial for learning and memory, records each event in three different forms or “copies”.
These ‘”copies” are disseminated among different groups of neurons that arise at various stages during embryonic development.
1️⃣ The early-born neurons ensure the longevity of a memory creating a copy that, although initially weak, strengthens over time. This memory becomes more accessible to the brain long after its formation, allowing the preservation of memories in the long term.
2️⃣ The late-born neurons produce a memory copy that is very strong initially but fades quickly. This memory is easier to modify shortly after formation, allowing new information to be integrated or errors corrected.
3️⃣ The last group of neurons present an interesting compromise – a memory copy that remains stable over time.
These 3️⃣ memory copies function together, enhance the brain’s memory dynamics and reinforce its plasticity.
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How many phase changes of matter are there?
📌 A phase change or phase transition is a change between solid, liquid, gaseous, and sometimes plasma states of matter.
📌 The main factors that cause phase changes are changes in temperature and pressure. At the phase transition the two states of matter have identical free energies and are equally likely to exist.
❗️ There are 8️⃣ phase changes between solids, liquids, gases, and plasma.
Melting (Solid→Liquid)
Freezing (Liquid→Solid)
Vaporization or Evaporation (Liquid→Gas)
Condensation (Gas→Liquid)
Deposition (Gas→Solid)
Sublimation (Solid→Gas)
Ionization (Gas→Plasma)
Deionization or Recombination (Plasma→Gas)
✍️
A solid can melt into liquid or sublimate into gas.
A liquid can freeze into a solid or vaporize into a gas.
A gas can deposit into a solid, condense into a liquid, or ionize into plasma.
Plasma can deionize or recombine to form a gas.
ℹ️ There are additional phase changes in condensed matter physics or metallurgy.
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How are the main states of matter defined?
📍 Solid
is a state of matter with a defined shape and volume. Atoms, ions, and molecules in a solid pack tightly together and may form crystals.
📍 Liquid
is a state of matter with a defined volume, but no defined shape, as liquids take the shape of their container. Particles in a liquid have more energy than in a solid, so they are further apart and less organized (more random).
📍 Gas
is a state of matter lacking either a defined volume (like a liquid) or defined shape easily expanding or contracting (unlike a liquid). Particles in a gas have more energy and move more randomly than in solids or liquids.
📍 Plasma
is a state of matter similar to a gas, except all of the particles carry an electrical charge, exist at very low pressure and are even further apart than in a gas. Plasma can consist of ions, electrons, or protons. Examples of plasma include lightning, the aurora, the Sun, and the inside of a neon sign.
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How did a prehistoric bird use its teeth?
When the first fossil of Longipteryx chaoyangensis was found in 2020, paleontologists thought its toothed beak suggested it ate fish. Scientists initially compared the ancient bird to the contemporary kingfisher because of its similarly-shaped skull and beak, and diet of small fish, but that resemblance turned out to be a red herring.
A more recent look inside a specimen’s stomach showed the bird — which lived 120 million years ago in what’s now northeastern China — fed on fruit-like plants.
Longipteryx had disproportionately large teeth toward the front of the beak, and the thickness of those teeth’s enamel resembles that of a hyper-carnivore, akin to a meat-eating dinosaur like Allosaurus. Now, scientists suppose that those features weren’t meant for eating, and Longipteryx was using its head as a weapon, just like modern hummingbirds wield their long, narrow beaks as air-born swords to fight off competition for food.
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What was the most spectacular vacuum experiment?
📍 The most spectacular vacuum experiment was performed by a German scientist Otto von Guericke (1602-1686), the inventor of the air pump. In 1654, he evacuated the air from inside a pair of joined metal hemispheres and attached a group of horses to each end. The external air pressure that acted on the hemispheres was so strong that even 30 animals could not pull them apart ⬆️.
📍 The first artificial vacuum was produced in 1643 by an Italian physicist and mathematician Evangelista Torricelli (1608-1647), a pupil of Galileo Galilei (1564-1642). Torricelli used the vacuum in his invention of the mercury barometer. He filled a glass tube (with one end sealed off) with mercury and then immersed it in a basin of the liquid metal. An empty space formed at the upper end of the tube, the size of which varied depending on the air pressure, which led Torricelli to assume that it has to be a void.
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What is the concept of Ahimsa?
🔺 The concept of Ahimsa is an ancient Indian principle of non-violence, non-injury or absence of desire to harm any life forms.
🔺 Ahimsa originated in Jainism, an Indian religion, and is also an important principle in Buddhism, Sikhism, and Hinduism.
🔺 Mahatma Gandhi’s philosophy of non-violence was also profoundly influenced by Ahimsa.
ℹ️ 🗓 No wonder that World Compassion Day (WCD), an annual observance held on November 28, originated in India. WCD was founded in 2012 by Pritish Nandy, an Indian poet, journalist, film producer, media and television personality, politician, and activist. While many international days serve as moments of reflection, WCD stands out by inspiring individuals and influential personalities worldwide to act, to speak on their beliefs, aligning non-violence and compassion with the trials and tribulations of the contemporary era. The first WCD was held in Mumbai and was dedicated to animal welfare.
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How many hazards do humans encounter in space journeys?
🧑🚀🚀 Cosmonauts encounter five main hazards as they journey through space.
Space radiation
Invisible to the human eye, it is not only stealthy but considered one of the most hazardous aspects of spaceflight.
Isolation and confinement
Behavioral responses occur among groups of people far from Earth who are isolated and confined in a small space over a long period of time.
Distance from Earth
Instructions, new supplies, medical care, and more become increasingly challenging to receive from Earth as humans venture deeper into space.
Gravity (and the lack of it)
Astronauts' entire bodies – muscles, bones, inner ear, and organs – must adjust to the new gravities encountered in space and on other planets, and Earth once they return home.
Closed or hostile environments
Maintaining a safe ecosystem inside a spacecraft (optimal temperatures, pressures, lighting, microbial communities, etc.) presents unique challenges.
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Who were the earliest carpenters?
📌 The pair of interlocking logs joined by an intentionally cut notch ⬆️ was unearthed beneath a bank of Zambia’s Kalambo River by archaeologists.
📌 Dating to nearly half a million years ago, this discovery radically changed scholars’ views of the capabilities of people of the past.
📌 Researchers believe the logs may have formed part of a walkway or the foundation of a platform built over wetlands.
📌 The 476,000-year-old log structure was likely the handiwork of the archaic human species Homo heidelbergensis.
📌 Scientists haven’t seen archaic humans manipulating their environment on such a large scale before.
📌 At the same site, the team also unearthed stone axes and 4️⃣ wooden tools – a digging stick, a wedge-shaped object, a notched branch, and a flattened log ⬆️ – dating to 390,000-324,000 years ago.
ℹ️ Prior to this discovery, the oldest known surviving wooden structures were built by people living around 11,000 years ago.
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What is the closest exoplanet that might have an ocean of liquid water?
The exoplanet LHS 1140 b is one of the closest discovered planets that lies within its star’s habitable zone — the region where a planet could retain liquid water – and might have an atmosphere and an ocean of liquid water.
⬆️ According to an international scientists’ team, LHS 1140 b might be what’s called an eyeball planet, with a single liquid ocean surrounded by ice. Or it might be entirely ice-covered, with an ocean below the ice, similar to Jupiter’s moon Europa or Saturn’s moon Enceladus.
Located only 48-49 light-years away in the constellation Cetus, LHS 1140 b is 1.7 times the size of our planet Earth and is the most promising habitable zone exoplanet yet in search for liquid water beyond the Solar System.
The team hopes to determine the planet’s surface characteristics and delve deeper into its atmosphere. It will likely take years to obtain all the needed data.
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What is the difference between a “normal” and a mass extinction?
✔️ Extinction is a part of life, and animals and plants disappear all the time.
✔️ When a species disappears, scientists say that a species goes extinct.
✔️ From an evolutionary perspective, the role of species that become extinct in the ecosystem is usually filled by new species, or other existing ones.
❗️ Earth's 'normal' extinction rate is often thought to be somewhere between 0.1 and 1 species per 10,000 species per 100 years. This is known as the background rate of extinction.
✔️ However, during the history of life on Earth, there have been periods of mass extinction.
❗️ A mass extinction event is when species vanish much faster than they are replaced. This is usually defined as about 75% of the world's species being lost in a short period of geological time - less than 2.8 million years.
ℹ️ About 98% of all the organisms that have ever existed on our planet are now extinct.
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What organisms are holobionts?
According to modern scientists, organisms are holobionts, and life is sympoietic.
The term “holobiont” refers to the scientific conclusion that organisms are integrated consortia of a host organism plus numerous species of other symbiotic organisms.
With few (if any) exceptions, animals and plants are holobionts, federated partnerships of numerous species functioning together to generate a healthy organism.
For example:
🧍♂️🧍♀️In the adult human body, microbes account for approximately half of cells, and these bacteria, fungi, protists, and archaea are critical for healthy physiology, development, and immunity.
🐄 Cows are herbivores, but there are no genes in their bovine nuclei that encode grass-digesting enzymes, and these cellulose-digesting enzymes come from the set of microbes living within the rumen of the cattle’s guts.
🪸 In coral, most of the animal’s carbon resources are derived from the photosynthetic reactions of its algal symbionts.
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How to collect energy from raindrops?
💦 Raindrops falling from the sky can produce a small amount of energy that can be harvested and turned into electricity.
Researchers have recently proposed several different devices for harvesting such dispersed hydropower.
One of the last inventions is a superhydrophobic magnetoelectric generator (MSMEG) ⬆️.
It consists of 5️⃣ parts:
📍a superhydrophobic magnetic material-based film (SMMF)
📍a coil
📍a NdFeB magnet
📍an acrylic housing
📍an expandable polystyrene (EPS) base.
According to scientists, the MSMEG can quickly charge a commercial capacitor with 2.7 V/1 F to 1.18 V within 200 seconds and power diverse electronic devices, e.g. LEDs and fans.
The authors of this study believe that such an MSMEG may provide a promising strategy for efficiently harvesting dispersed raindrop energy.
However, there are also opinions that such technologies are difficult to develop on a large scale and have limited practical application.
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What is the minimum of light required for plants to grow?
🌿☀️ Plants can grow with much less light than previously thought, according to a new study.
✅ Researchers lowered light sensors into Arctic water to a depth of 50 metres (164 feet) to test how low light levels must become before plant life ceases to exist and found that tiny water-based organisms called microalgae were able to perform photosynthesis with very little light ⬆️.
✅ The microalgae carry out this process at the lowest light levels ever recorded – just 0.04 micromoles of photons.
✅ This isn’t very far from what computer simulations predict to be the lowest light possible in any circumstances – 0.01 micromoles of photons.
✅ Typical light conditions outside on a clear day are between 1,500-2,000 micromoles of photons – more than 37,000-50,000 times the amount of light required by those microalgae.
ℹ️ This research can potentially make it easier to grow plants in areas with little sunlight and even in space.
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Could the Sahara be green again and will Africa finally need its “Great Green Wall”?
🟢 Africa’s “Great Green Wall” initiative was launched to hold back the Sahara from expanding southward.
🟢 This year, after an unusual influx of rain, scientists have compared satellite imagery on September 12, 2024 (⬆️upper image), versus the same day in 2023 (⬆️lower image), and have seen that the southern Sahara’s vegetation reached much farther north in 2024.
ℹ️ Where the trade winds from each hemisphere meet near the Equator is a low-pressure zone, the intertropical convergence zone (ICZ).
🟢 According to researchers, most climate models suggest that the ICZ is the reason for Africa’s greening and farther northward “green” shifts in this zone could happen more frequently in the next decades.
🟢 So, in the distant future, it is very possible that the Sahara could turn green again and Africa, at least for a certain period of time, won’t need its “Great Green Wall”.
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Who left Paleozoic “dumbbells”?
All over the world, scientists find dumbbell-shaped fossils in rock outcrops that are called Bifungites and are not fossilized animals but burrows left in an extinct creature’s wake. ⬆️ Most are found in rocks from the Paleozoic era more than 300 million years ago.
🪱 Not long ago, Brazilian paleontologists, exploring the bed of the Sambito River in northeastern Brazil, found imprints of small worms inside Bifungites, indicating that these organisms produced them.⬆️
Researchers suggest that:
📌 the marine worms that made Bifungites belonged to a group called Annulitubus
📌 species in the group lived in the shallow part of the ocean near the shores of prehistoric supercontinents and dug burrows into the seabed.
📌 the Annulitubus worms made these burrows to protect themselves against savage storms or probing predators
📌 the worms potentially wedged themselves into the peculiar bulging or arrow-like ends of the chamber.
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Where do the most genetically diverse people on Earth live?
🌍 The most genetically diverse people on Earth live in Africa.
Geneticists have discovered more than 3 mln previously undescribed genetic variants among Africans.
That diversity has fit well with the fossil evidence that the human species originated in Africa. It is known that when a new species, be it plant or animal, arises and spreads, genetic differences accumulate more in geographic regions where the species has been present longer. The more distant populations represent only a small subset of the genetic variation that arose nearer the center of origin.
The claim has even been made that East Africans are more genetically different from West Africans than Europeans are from Asians.
According to researchers:
✔️🇳🇦🇿🇦the southwestern coast of Africa-between today’s Namibia and South Africa-may be modern humanity’s homeland
✔️the oldest group in Africa, evolutionarily speaking, may be the San, or Bushmen.
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What are exotic states of matter that require special conditions?
📍 Bose-Einstein Condensate (BEC)
is sometimes called the fifth state of matter. In Bose-Einstein condensate, atoms and ions stop behaving as separate particles and collapse into a single quantum state that can be described using a single wavefunction. This state of matter was verified experimentally in 1995 by Eric Cornell and Carl Wieman. Bose-Einstein condensate is “colder” than an ordinary solid and may form very near absolute zero.
📍 Superfluid
is a second liquid state formed by some types of matter. A superfluid displays zero viscosity. In other words, it has no resistance to flow. Superfluidity was observed for helium in 1937. Because it could flow without friction, superfluid helium climbed the walls of its container and dripped over the sides. Like Bose-Einstein condensate, superfluidity occurs near absolute zero.
📍 Fermionic Condensate
is a state of matter similar to a Bose-Einstein condensate, except it consists of fermions, such as quarks and leptons. Normally, the Pauli exclusion principle forbids fermions from entering the same quantum state. In a fermionic condensate, a pair of fermions behaves as a boson, allowing multiple pairs to enter the same quantum state.
📍 Rydberg Matter
is a type of plasma formed when excited ions condense. You can think of it as dusty plasma. So far, it occurs in the elements hydrogen, potassium, nitrogen, and cesium. This type of matter consists mainly of small hexagonal planar clusters. Scientists make Rydberg matter in a lab or observe it in the upper atmosphere of planets and in clouds in space.
📍 Photonic Matter
is the state of matter formed when photons interact with a gas in such a way that the photons have apparent mass and can interact with each other. Photons with apparent mass can even form photonic “molecules.”
📍 Color-Glass Condensate
is a state of matter proposed to exist when atomic nuclei travel near the speed of liquid. Because of their speed, the nucleus appears compressed along its direction of motion. This causes the gluons of the nucleus to appear as a sort of wall or region of increased density.
📍 Other States of Matter
There are other proposed states of matter, including quark matter, degenerate matter, dropleton, quantum Hall state, superglass, supersolid, and string-net liquid.
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What is a state of matter?
✔️ Matter is anything that has mass and takes up space. It consists of subatomic particles, atoms, ions, and compounds. Sometimes these particles are tightly bound and close together, while other times particles are loosely connected and widely separated.
✔️ States of matter are forms in which matter exists, they describe the qualities displayed by matter. Basically, the state of matter of a substance depends on how much energy its particles have.
✔️ It’s possible to change the energy of matter by altering its temperature or pressure, causing matter to transition from one state to another. But, when matter changes state, its chemical identity remains the same. For instance, if you take ice, melt it, and then boil it, its state of matter changes, but it’s always water.
✔️ The four fundamental states of matter that are observable in everyday life, but scientists are discovering new states of matter that exist under extreme conditions.
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How did the largest pterosaurs fly?
Pterosaurs were the first vertebrates that evolved powered flight, but it has long been debated whether the largest pterosaurs could fly at all.
Scientists were lucky to find in Jordan three-dimensionally preserved bones of two different large-bodied azhdarchoid pterosaur species. These rare fossils have enabled experts to hypothesize that not only could the largest pterosaurs take to the air, but their flight styles could differ too.
Newly collected bones of the already-known giant pterosaur, Arambourgiania philadelphiae, with 10-meter wingspan resemble wing bones of modern vultures, whose flight style is soaring (sustained powered flight requiring launch and maintenance flapping).
A new, smaller species Inabtanin alarabia with circa 5-meter wingspan had flight bones that are similar to those of modern flapping birds. it is likely that Inabtanin flew this way (although this does not preclude occasional use of other flight styles too).
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Can a vacuum be totally empty?
📌 A vacuum is a volume empty of matter, sometimes called ‘free-space’.
❗️ In practice, only partial vacuums are possible.
📌 Outer space can approach the requirements of a vacuum, but even in space there are a few atoms per cubic meter.
📌 Vacuum is not a force. Though the net motion of matter from a region of higher to lower concentration does appear to be due to a force – e.g. inside a vacuum cleaner, gas concentration is about 20% lower than ambient, so air and dust will be ‘sucked’ in.
✍️ Contrary to popular belief, a vacuum cannot be made simply by sucking the molecules out of the container space. Molecules move in every direction and bounce, and to get the molecules out, one need to wait until they come towards you out of their own ‘free will’, and then ‘bat them’ out of the enclosure using a high speed propeller called a turbo pump. It is often necessary to use more than one type of pump to achieve a reasonably good vacuum!
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Why food may taste weird in space?
📌 Despite being given carefully designed diet plans ⬆️, astronauts have reported that meals taste bland and that they were not meeting their nutritional needs, which can be dangerous for long-term missions. Astronauts typically only meet about 80% of their energy needs in space.
📌 Scientists already knew that low-gravity causes fluid to shift from the lower to the upper parts of the body, creating facial swelling and nasal congestion which affects smell and taste. But these symptoms begin to disappear within a few weeks.
📌 Researchers have found that spatial perception can play a significant role. A greater sense of loneliness and isolation — which astronauts may experience in space — can influence how people smell and taste their food.
📌 One of the long-term aims of the study is to make better tailored foods for astronauts, as well as other people who are in isolated environments, to increase their nutritional intake closer to 100%.
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What is gaslighting?
✔️Gaslighting is a form of psychological abuse whereby a person or group may intentionally or unintentionally manipulate one or more people into questioning their sanity and perception of reality to exert power or control over others with the goal of manipulating them.
✔️Those experiencing gaslighting may often feel confused about their version of reality, experience anxiety, or be unable to trust themselves. Gaslighting can have severe consequences on mental health.
✔️The term gaslighting originates from the 1938 play and subsequent 1944 movie titled ‘Gaslight’ in which a husband attempts to drive his wife crazy by dimming the lights (which were powered by gas) in their home, and then he later denies that the light changed when his wife points it out.
✔️Gaslighting is mostly known to be carried out by one person onto another person, commonly in romantic relationships, but can also occur in friendships, between family members, in the workplace, or politics.
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What are whistlers and how far can they reach?
🔘 A whistler is a very low frequency (VLF) radio wave generated by different types of lightning, including volcanic lightning.
🔘 These special electromagnetic waves are so named because they can be converted to sound signals and, with a VLF receiver, anyone can listen to the everyday melody of millions of lightning bolts (even if not every lightning bolt becomes a whistler). A listener in New Zealand can even hear a volcano in Alaska erupt.
🔘 Frequencies of terrestrial whistlers are 1 kHz to 30 kHz, with maximum frequencies usually at 3 kHz to 5 kHz.
🔘 For decades, researchers thought lightning-induced whistlers would remain trapped relatively close to Earth’s surface, below about 1,000 km.
⚡️ Now scientists have discovered that whistlers can reach distances up to 20,000 km above the planet’s surface, travelling deep into the highest layers of the atmosphere, where it could threaten the safety of satellites and astronauts.
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How many mass extinctions have there been and which one was the most devastating?
In the last 500 million years, five great mass extinction events have changed the face of life on Earth. We know what caused some of them, but others remain a mystery.
1️⃣ The Ordovician-Silurian mass extinction occurred 443 million years ago and wiped out approximately 85% of all species. Scientists think it was caused by temperatures plummeting and huge glaciers forming, which caused sea levels to drop dramatically. This was followed by a period of rapid warming. Many small marine species died out.
2️⃣ The Devonian mass extinction event took place 374 million years ago and killed about three-quarters of the world's species, most of which were marine invertebrates that lived at the bottom of the sea. This was a period of many environmental changes, including global warming and cooling, a rise and fall of sea levels and a reduction in oxygen and carbon dioxide in the atmosphere. We don't know exactly what triggered the extinction event.
3️⃣ The Permian mass extinction, which happened 250 million years ago, was the largest and most devastating event of the five. The Permian-Triassic extinction event is also known as the Great Dying. It eradicated more than 95% of all species, including most of the vertebrates which had begun to evolve by this time. Some scientists think Earth was hit by a large asteroid which filled the air with dust particles that blocked out the Sun and caused acid rain. Others think there was a large volcanic explosion which increased carbon dioxide and made the oceans toxic.
4️⃣ The Triassic mass extinction event occurred 200 million years ago, eliminating about 80% of Earth's species, including many types of dinosaurs. This was probably caused by colossal geological activity that increased carbon dioxide levels and global temperatures, as well as ocean acidification.
5️⃣ The Cretaceous mass extinction event occurred 66 million years ago, killing 78% of all species, including the remaining non-avian dinosaurs. This was most likely caused by an asteroid hitting the Earth in what is now Mexico, potentially compounded by ongoing flood volcanism in what is now India.
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How can plants cope with stresses and even “speak” to fungi?
Abiotic stresses, such as nutrient deficiency, drought, high temperature, and light stress, are significant limiting factors of plant survival and growth.
Scientists already knew that plant hormones (phytohormones), organic molecules that cause signaling effects in plant tissues, play an essential role in enhancing plant tolerance by responding to abiotic stresses.
But several recent studies have shown that strigolactones (SLs), carotenoid derivatives that occur naturally in plants, are novel phytohormones that regulate plant metabolism and growth, and help to cope with various stresses, e.g. by initiating physiological responses against drought stress.
SLs are also crucial for the interaction of plants with soil microorganisms like fungi, providing inter-kingdom communication.
In addition to attracting microorganisms, SLs affect photosynthesis, bridge other phytohormones, induce metabolic compounds.
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Why are moiré patterns important for materials science?
The so-called moiré patterns are motifs that emerge when two repetitive structures are overlaid.
This phenomenon is well known from computer or TV screens: when looking at a finely striped pattern, e.g. on a shirt, the stripes do not look evenly spaced and seem to bend in some areas. While undesirable in this case, the moiré effect can indeed be surprisingly useful.
Two atomically thin materials can be overlapped to create a new material, in which the atomic structures of the two produce a moiré pattern.
Some of these moiré materials exhibit astonishing properties, drastically different from those of their components, which may be applied in science, e.g. in novel nano-electronic devices.
The term originates from a French word moiré, a type of textile, traditionally made of silk but now also made of cotton or synthetic fiber, with a rippled or "watered" appearance, by pressing two layers of the textile when wet.
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How many people live in cities today?
🏙 Today, about 4.6 billion or 57% of the more than 8 billion people worldwide live in urban areas, according to different sources.
🌇 By 2050 this proportion is expected to increase to 68%, adding another 2.5 billion people to urban areas.
🏙 Today, the most urbanized regions include Northern America (with 82% of its population living in urban areas in 2018), Latin America and the Caribbean (81%), Europe (74%) and Oceania (68%).
🌇 A UN report notes that future increases in the size of the world’s urban population are expected to be highly concentrated in just a few countries. Together, India, China and Nigeria will account for 35% of the projected growth of the world’s urban population between 2018 and 2050, adding respectively 416, 255 and 189 million urban dwellers.
🏙 At present there are 3️⃣4️⃣ cities worldwide with more than 10 million inhabitants.
🎉⬆️ World Cities Day, designated by the UN, is celebrated annually on 31 October.
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Do migratory birds save energy escaping winter?
✔️ Scientists have long surmised that birds migrate during winters to save energy: far away from the biting cold, birds would need to expend less energy to keep themselves warm.
✔️ A new study has shown that migratory lifestyle carries no added overall energy cost.
✔️ Scientists have found partially migratory Eurasian blackbirds (Turdus merula) ⬆️ migrating to warmer regions in winter didn’t save more energy compared to members of the same species that stayed behind.
✔️ To measure the birds’ heart rate and body temperature over the course of the winter, researchers used surgically implanted biologgers.
✔️ It was also found that migrating birds started saving energy for migration by lowering their heart rate and body temperature almost a month before their departure.
✔️ The research raises important questions on why birds migrate if there’s no energy benefit, and where the unaccounted energy is being used instead.
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