CULTURAL QA 05-2023-29A BY Mr G AND EDITED BY KR IRS 28523 Q5 Why does an airplane need full throttle for take-off but right after it the pilot "slows" it down?
Quora answers need not be 100% correct answers. KR Repeated. Full throttle is not necessary for take-off. Q6 Where did modern humans come from? KR G stunt. He will sweep all in delete; but will redo as if his original. Anyway, if he had read perfectly would have been better. Those who cannot understand what G wrote; or missed mine dated 12th May 2023 which is once again given; may read below which came long ago. I had already said that Darwin is wrong; African theory is wrong; and now science says so; later they will accept China; then they will accept india. Thank You. NOW (dated 12/5/23 sent by KR): ” Neanderthal Skeleton Discovery Changes What We Know About Human Evolution A"truly extraordinary" Neanderthal skeleton covered in "cave popcorn" is shedding new light on some of the mysteries of human evolution. Known as the "Altamura Man," it is one of the best-preserved Neanderthal specimens yet discovered and probably the most complete. Giorgio Manzi, a researcher with Sapienza University of Rome, told Newsweek the Altamura skeleton "is a truly extraordinary discovery, of enormous interest for our knowledge of Neanderthals, ourselves as a species and human evolution in general." The skeleton is trapped deep in a cave system near the town of Altamura, southern Italy. It was found in 1993, but has never been moved for fear of damage. "Being able to study this Neanderthal—especially if it were eventually extracted from the limestone, with all the necessary precautions—would mean having the possibility of clarifying aspects of human evolution which, otherwise, simply would not be knowable," Manzi added. "Unfortunately, that extraordinary scientific heritage is still there, as if it were a prisoner of the calcareous concretions that have enveloped it over the course of tens of thousands of years." Now Manzi and his fellow researchers have discovered that the skeleton's cranium has a combination of features never before seen in the species. Their study, published in the Nature journal Communications Biology, suggests one of the major theories of Neanderthal evolution needs to be reassessed. Neanderthals—Homo neanderthalensis—are one of our closest ancient relatives and lived in Eurasia until disappearing around 40,000 years ago. Evidence indicates that they emerged in the Middle Pleistocene, which ran from around 780,000 to 126,000 years ago. The earliest Neanderthal-like fossils are about 430,000 years old, but major parts of the Neanderthal origin story remain unclear. Altamura Man's skull might change that. Manzi said his team had to conduct a "virtual excavation" so they could digitally reconstruct the cranium. This revealed a "very peculiar combination" of physical traits, Manzi said. "I would say unique." Some of the cranium's features are typical of Neanderthals. Others appear more ancient, comparable to specimens hundreds of thousands of years older. Some even resemble those in an earlier and potentially distinct human species, Homo heidelbergensis. Altamura Man lived between around 130,000 and 170,000 years ago, according to scientists. This period is marked by the transition between Homo heidelbergensis and the Neanderthals, but the Italian specimen does not appear to fall neatly into either category. "One could almost say that, on the basis of the characteristics observed on the cranium, the Italian specimen is more likely to be the last representative of the species Homo heidelbergensis rather than being among the earliest Homo neanderthalensis," Manzi said. The unexpectedly archaic features led the researchers to hypothesize that the southernmost regions of the Italian peninsula may have provided a "refuge" for ancient humans during the coldest phases of the Middle Pleistocene and the Upper Pleistocene (around 126,000 to 12,000 years ago). As a result, Manzi said there might have to be a rethink of aspects of the "accretion model," one of the main hypotheses of Neanderthal evolution. It states that Neanderthals evolved in partial or complete genetic isolation from the rest of humanity, through the gradual accumulation of distinctive physical traits in European populations. The latest study shows that the accretion model can only be accepted if the varied environmental conditions of different European regions are taken into account. In some areas, local conditions may have accelerated the process. In others—such as southern Italy—local conditions may have slowed down this process. The Altamura cranium straddles two chambers within the cave system. Most of the skeleton is encased in mineral deposits that have formed over tens of thousands of years. Why Is Altamura Man Still in the Cave? And What Is Cave Popcorn? Studying the Altamura specimen is not easy. It is located deep in the Lamalunga cave system, which can only be reached using special equipment. To make it more difficult, the skeleton is suspended within a sheet of mineral deposits, so only parts of it are visible. It straddles two distinct chambers in the cave, which are separated by the mineral "curtain." It is also covered in coralloids—or "cave popcorn"—small, bulbous mineral structures that form on surfaces in caves. The arrangement of the bones indicate that Altamura Man might have collapsed and died in the spot where his skeleton remains. One possibility is that he fell down a shaft in the cave complex and was unable to escape. Scientists have long hoped to bring Altamura Man back to the surface, so the skeleton can be examined thoroughly in a lab. But until they have a plan to excavate the specimen without causing irreparable damage, the Italian authorities will not issue a permit. For now, working in the cave is the only option. Although the skeleton was found in 1993, it took another 22 years before a team of researchers—including Manzi—confirmed it was a Neanderthal. In their latest study, Manzi and his colleagues wanted to examine the skeleton's cranium, but not all the skull can be seen in the cave. One side of the cranium faces into the back chamber, which is inaccessible. Only a few gaps in the mineral curtain allow researchers to peek into the chamber. Probes were used for a "virtual excavation" of the skull and the information gathered helped the team create a digital reconstruction of the complete cranium. This allowed the scientists to examine the shape of the cranium as a whole, in detail, for the first time. xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx G A6 New study adds twist to theory of our evolution A new study has now introduced a new twist in the tale of evolution as scientists propose that modern humans descended from two populations. New Delhi, UPDATED: May 19, 2023 18:55 IST Human evolution The research indicated that multiple ancestral groups from across Africa contributed to the emergence of Homo sapiens. Study taps into genome data from modern-day African populations. The findings did not support a longstanding hypothesis. Multiple groups from across Africa contributed to emergence of Homo sapiens By India Today Science Desk: Where did modern humans come from? The question is key to the study of evolution and it was believed that we all had our humble origins from a single group of ancestors that came out of Africa, until now. A new study has now introduced a new twist in the tale of evolution as scientists propose that modern humans descended from two populations that lived in Africa for a million years individually before merging across the continent, indicating that there is no single birthplace of humanity. It taps into genome data from modern-day African populations, offering insight into how this may have unfolded. The study published in the journal Nature states that despite broad agreement that Homo sapiens originated in Africa, considerable uncertainty surrounds specific models of divergence and migration across the continent. Evolution It has been long held that modern humans sprang across the world from Africa. (Photo: Getty) "Decades of study of human genome variation have suggested a predominantly tree-like model of recent population divergence from a single ancestral population in Africa. t has been difficult to reconcile this finding with the fossil and archaeological records of human occupation across the vast African continent," researchers said in the paper. The global team of researchers from different institutions analysed the genomes of 290 living people and conducted large-scale simulations of human history feeding multiple scenarios of different populations existing in Africa to the software which could produce the diversity of DNA found in people living today. The research indicated that multiple ancestral groups from across Africa contributed to the emergence of Homo sapiens in a patchwork manner, migrating from one region to another and mixing with one another over hundreds of thousands of years. The team analysed DNA from different groups arising in Africa from Mende, farmers living in Sierra Leone in West Africa to the Gumuz, a group descended from hunter-gatherers in Ethiopia; the Amhara, a group of Ethiopian farmers; and the Nama, a group of hunter-gatherers in South Africa, the New York Times reported. Neandrathal The team looked at 50,000-year-old Neanderthal found in Croatia, another close relative of ancient humans. It has long been held that modern humans sprang across the world from Africa as the oldest fossil was unearthed on the continent. The fossil was 3,00,000 years old and archeologists have also found the oldest stone tools from the region as well, hinting at some sort of human settlement. The team compared the DNA of African people in the study with that of a person from Britain and the genome of a 50,000-year-old Neanderthal found in Croatia, another close relative of ancient humans. They concluded that the ancestors of our species existed in two different population groups dubbed Stem1 and Stem2 by the team led by Dr. Brenna Henn, a geneticist at the University of California, Davis. It also found that everyone alive today can trace their ancestry to at least two distinct populations that were present in Africa dating back about a million years. "All humans share a relatively recent common ancestry, but the story in the deeper past is more complicated than our species evolving in just a single location or in isolation," said University of Wisconsin-Madison population geneticist Aaron Ragsdale, lead author of the study. The ancestral groups were likely spread across a geographic landscape in a population structure that, Ragsdale said, "was 'weak,' meaning that there was ongoing or at least recurrent migration between groups, and this maintained genetic similarity across ancestral populations." The fossil record is scanty in the time period that would be most informative about the emergence and spread of Homo sapiens, and there is no ancient DNA from skeletal or dental remains from these time periods, the researchers said. The above QA is based on the front page article in yahoo opening page on 29-5-23. Compiled and posted by R. Gopala Krishnan, former ITS, on 29-05-2023 K Rajaram IRS 28523 On Sun, 28 May 2023 at 19:30, 'gopala krishnan' via Thatha_Patty < [email protected]> wrote: > *CULTURAL QA 05-2023-29A* > > Q1 Why do we use AC but not DC in households? > > A1 Info Sage, Former Insight Investigator (2018–2022) May 22 > > Why we use AC (alternating current) instead of DC (direct current) in > households in a simple and understandable way. Here are the reasons: > > 1. Efficient Generation and Transmission: AC is more efficient for > generating and transmitting electricity over long distances. It can be > easily transformed to different voltage levels using transformers, which > allows for efficient transmission over power lines. This is essential for > delivering electricity from power plants to homes and businesses located > far away. > > 2. Safety: AC electricity is safer to use in households compared to > high-voltage DC. In the early days of electricity, it was discovered that > AC can be easily transformed to lower voltages, making it safer for human > contact. This led to the development of distribution systems using AC, as > it reduced the risk of electrical shock and electrocution. > > 3. Voltage Regulation: AC can be easily regulated and controlled using > transformers and voltage regulators. This allows for adjustments in > voltage levels, which is important for matching the varying power > requirements of different devices in a household. It enables the use of > different appliances with varying voltage needs without the need for > individual power supplies. > > 4. Compatibility: Many appliances and devices are designed to operate on > AC power. AC is the standard form of electrical power supplied to homes > and businesses, and most electrical appliances, such as lights, > refrigerators, televisions, and air conditioners, are designed to run on AC > power. Switching to DC would require significant changes in infrastructure > and the development of new DC-compatible devices. > > 5. Power Transmission Grid: The existing power transmission and > distribution infrastructure, including power grids and substations, are > designed for AC power. Replacing the entire infrastructure with DC systems > would be costly and impractical. > > Q2 What is the best time to eat guava? > > A2 Debasish, Health and Fitness expert - Since 20128h > > There isn't a specific "best" time to eat guava that applies to everyone, > as it ultimately depends on personal preferences and dietary needs. Guava > is a nutritious fruit that can be enjoyed at different times of the day > based on individual preferences. Here are a few suggestions: > > Breakfast: Guava can be a great addition to your breakfast. You can enjoy > it as a standalone fruit or incorporate it into smoothies, yogurt bowls, or > cereal. > > Snack: Guava makes for a refreshing and healthy snack option. You can > have it during mid-morning or afternoon to satisfy hunger and provide a > boost of energy. > > Pre-workout: The natural sugars and carbohydrates in guava can provide a > quick source of energy. Eating guava before a workout can be beneficial, > but make sure to give yourself enough time to digest before exercising. > > Dessert: Guava's sweet and tangy flavour makes it a delicious choice for > desserts. You can use it in fruit salads, tarts, or even make guava jelly. > > *Ultimately, you can enjoy guava whenever it suits your taste and fits > well into your daily routine*. It's important to note that guava is high > in fibre, so eating it in moderation and balancing it with other nutritious > foods is recommended. > > Q3 Can a Boeing 747 be flown by one pilot? > > A3 Vishnu Ravi, Aviation Enthusiast | Content Creator Sat > > Certain small business jets have the potential to be piloted by a sole > individual. Nevertheless, *when it comes to commercial jets responsible > for transporting passengers and cargo, a minimum of two pilots is required*. > > > Some airlines and manufacturers have raised the concept of a single pilot > in the cockpit of commercial aircraft, but it has yet to receive regulatory > approval. *The presence of two fully qualified and experienced pilots in > each cockpit holds the utmost importance for ensuring safety.* > > In relation to the Boeing 747, it is not designed to operate with just one > engine, although it can sustain flight on a single engine for approximately > three hours in the event of an emergency, enabling it to reach the nearest > airport. *However, flying a 747 with only one engine is not advisable, as > the aircraft is not engineered to be flown by a lone pilot.* > > It is essential to understand that aircraft receive certification for > operation with a specific crew size, and there are jets certified for > single-pilot operations. However, this certification does not extend to > commercial jets carrying passengers and cargo, as they necessitate a > minimum of two pilots in the cockpit for safety considerations. > > To sum up, a Boeing 747 cannot be piloted by a single individual, and > commercial jets responsible for carrying passengers and cargo require a > minimum of two pilots in the cockpit. While certain small business jets > can be operated by a lone pilot, the concept of a single pilot in the > cockpit of commercial aircraft has yet to gain regulatory approval. > > Q4 Why only a DC voltage is current used to run a train? > > A4 Mani. P, Manager at Jarmaaks Softtex > > DC (direct current) voltage is commonly used to power trains because of > several advantages it offers over AC (alternating current) voltage. Here > are some reasons why DC voltage is preferred for train systems: > > Simplicity of motor design: DC motors are simpler and more efficient > compared to AC motors, especially at low speeds. Trains require high > starting torques and frequent speed control, and DC motors can provide > smooth acceleration and deceleration with precise control. > > Regenerative braking: DC systems allow for efficient regenerative braking, > where the kinetic energy of the moving train is converted back into > electrical energy and fed back into the power supply. This energy can be > reused by other trains on the same line, reducing overall energy > consumption and improving efficiency. > > Power distribution: DC power distribution is more straightforward and > easier to control compared to AC systems. DC voltages are typically used > for third rail or overhead wire systems, where the power is supplied > directly to the train. AC power, on the other hand, requires complex > substations and transformers for voltage conversion, which adds > complexity and cost to the infrastructure. > > Compatibility with other systems: Many auxiliary systems in trains, such > as lighting, air conditioning, and control circuits, operate on DC voltage. > By using a DC power supply for propulsion, it becomes easier to integrate > and power these auxiliary systems directly without the need for additional > conversion devices. > > It's worth noting that some modern train systems, especially high-speed > trains, use a combination of AC and DC voltage. > > AC voltage is used for long-distance transmission and is converted to DC > for propulsion. This hybrid approach allows for efficient power > transmission over long distances while benefiting from the advantages of DC > motors for propulsion and control. > > Q5 Why does an airplane need full throttle for take-off but > right after it the pilot "slows" it down? > > A5 Srinidhi Kulkarni, Working as an engineer for 11 + years5h > > *During take-off, power is needed to overcome air drag, frictional force > from the ground (rolling resistance of the tires) and the force needed to > accelerate the aircraft to the required high speeds (which gives enough air > flow over the wings to generate lift).* > > During steady flight, power is needed to only overcome air drag and > maintain air speed. No frictional forces, no forces needed for acceleration. > > *All the above QA are from Quora website on 28--05- 2023.* > > *Quora answers need not be 100% correct answers.* > > Q6 Where did modern humans come from? > > A6 New study adds twist to theory of our evolution > > A new study has now introduced a new twist in the tale of evolution as > scientists propose that modern humans descended from two populations. > > New Delhi, UPDATED: May 19, 2023 18:55 IST > > *Human evolution* > > The research indicated that multiple ancestral groups from across Africa > contributed to the emergence of Homo sapiens. Study taps into genome data > from modern-day African populations. The findings did not support a > longstanding hypothesis. Multiple groups from across Africa contributed to > emergence of Homo sapiens > > *By India Today Science Desk: Where did modern* humans come from? The > question is key to the study of evolution and it was believed that we all > had our humble origins from a single group of ancestors that came out of > Africa, until now. > > A new study has now introduced a new twist in the tale of evolution as > scientists propose that modern *humans descended from two populations > that lived in Africa for a million years individually before merging across > the continent, indicating that there is no single birthplace of humanity.* > > It taps into genome data from modern-day African populations, offering > insight into how this may have unfolded. > > *The study published in the journal Nature states that despite broad > agreement that Homo sapiens originated in Africa*, considerable > uncertainty surrounds specific models of divergence and migration across > the continent. > > Evolution > > It has been long held that modern humans sprang across the world from > Africa. (Photo: Getty) > > "Decades of study of human genome variation have suggested a > predominantly tree-like model of recent population divergence from a single > ancestral population in Africa. > > t has been difficult to reconcile this finding with the fossil and > archaeological records of human occupation across the vast African > continent," researchers said in the paper. > > *The global team of researchers from different institutions analysed the > genomes of 290 living people and conducted large-scale simulations of human > history feeding multiple scenarios of different populations existing in > Africa* to the software which could produce the diversity of DNA found in > people living today. > > The research indicated that multiple ancestral groups from across Africa > contributed to the emergence of Homo sapiens in a patchwork manner, > migrating from one region to another and mixing with one another over > hundreds of thousands of years. > > The team analysed DNA from different groups arising in Africa from Mende, > farmers living in Sierra Leone in West Africa to the Gumuz, a group > descended from hunter-gatherers in Ethiopia; the Amhara, a group of > Ethiopian farmers; and the Nama, a group of hunter-gatherers in South > Africa, the New York Times reported. > > Neandrathal > > The team looked at 50,000-year-old Neanderthal found in Croatia, another > close relative of ancient humans. > > > > It has long been held that modern humans sprang across the world from > Africa as the oldest fossil was unearthed on the continent. *The fossil > was 3,00,000 years old and archeologists have also found the oldest stone > tools from the region as well, hinting at some sort of human settlement.* > > The team compared the DNA of African people in the study with that of a > person from Britain and the genome of a 50,000-year-old Neanderthal found > in Croatia, another close relative of ancient humans. *They concluded > that the ancestors of our species existed in two different population > groups dubbed Stem1 and Stem2 by the team led by Dr. Brenna Henn, a > geneticist at the University of California, Davis.* > > It also found that everyone alive today can trace their ancestry to at > least two distinct populations that were present in Africa dating back > about a million years. > > "All humans share a relatively recent common ancestry, but the story in > the deeper past is more complicated than our species evolving in just a > single location or in isolation," said University of Wisconsin-Madison > population geneticist Aaron Ragsdale, lead author of the study. > > The ancestral groups were likely spread across a geographic landscape in a > population structure that, Ragsdale said, "was 'weak,' meaning that there > was ongoing or at least recurrent migration between groups, and this > maintained genetic similarity across ancestral populations." > > The fossil record is scanty in the time period that would be most > informative about the emergence and spread of Homo sapiens, and there is no > ancient DNA from skeletal or dental remains from these time periods, the > researchers said. > > *The above QA is based on the front page article in yahoo opening page on > 29-5-23.* > > *Compiled **and posted by R. Gopala Krishnan, former ITS, on 29-05-2023* > > > > -- > You received this message because you are subscribed to the Google Groups > "Thatha_Patty" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/thatha_patty/2006021540.2450065.1685327421981%40mail.yahoo.com > <https://groups.google.com/d/msgid/thatha_patty/2006021540.2450065.1685327421981%40mail.yahoo.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "Thatha_Patty" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To view this discussion on the web visit https://groups.google.com/d/msgid/thatha_patty/CAL5XZoomnc%2BSRFDf46_W1Bf2OzoxC0gQ1kRcPU9NvY%3DRRL_ENA%40mail.gmail.com.
