Daily Quiz: UPSC Prelims Marathon (Science and Technology) – June 25, 2020

Polarimetry is a sensitive, nondestructive technique for measuring the optical activity exhibited by inorganic and organic compounds.

• A compound is considered to be optically active if linearly polarized light is rotated when passing through it.
• A team of astronomers has discovered that the closest known brown dwarf, Luhman 16A, shows signs of cloud bands similar to those seen on Jupiter and Saturn.
• The researchers used an instrument on the Very Large Telescope in Chile to study polarised light from the Luhman 16 system. Polarisation is a property of light that represents the direction that the light wave oscillates.
• The polarimetry technique is not limited to brown dwarfs. It can also be applied to exoplanets orbiting distant stars. The atmospheres of hot, gas giant exoplanets are similar to those of brown dwarfs.

A black hole is a place in space where gravity pulls so much that even light cannot get out. The gravity is so strong because matter has been squeezed into a tiny space. This can happen when a star is dying.

• The largest black holes are called “supermassive.” These black holes have masses that are more than 1 million suns together. Scientists have found proof that every large galaxy contains a supermassive black hole at its center.
• The supermassive black hole at the center of the Milky Way galaxy is called Sagittarius A. It has a mass equal to about 4 million suns and would fit inside a very large ball that could hold a few million Earths.
• Even if a black hole the same mass as the sun were to take the place of the sun, Earth still would not fall in.
• The black hole would have the same gravity as the sun. Earth and the other planets would orbit the black hole as they orbit the sun now.
• The sun will never turn into a black hole. The sun is not a big enough star to make a black hole.

Full moons can occur at any point along the Moon’s elliptical path, but when a full moon occurs at or near the perigee, it looks slightly larger and brighter than a typical full moon. That’s what the term “supermoon” refers to.

• Because supermoon is not an official astronomical term, there is no definition about just how close to perigee the full moon has to be in order to be called “super.”
• Generally, supermoon is used to refer to a full moon 90 percent or closer to perigee.
• A more accurate and scientific term is “perigee syzygy.” Syzygy is the alignment of three celestial bodies, in this case the Sun, Moon and Earth.

From millions, the population of the three Gyps species has been recently estimated to be about 20,000, i.e., 12,000 long-billed, 6,000 white-rumped and the rarest being the slender-billed vulture at 1,000.

• By 2000, the International Union for Conservation of Nature (IUCN) declared all these three species in its highest risk category – Critically Endangered.
• An avian population decline can be due to many factors – poaching, epidemics, habitat destruction – but none explained the rapidity, scale and expanse of the decline across South Asia.
• Initially, biologists reckoned that bioaccumulation of pesticides as a potential cause for the loss of vultures, like DDT that had poisoned bald eagles in the US in the 1960s.
• Ultimately, it took the minds of many nations – an international team of over a dozen scientists under the aegis of the Peregrin Fund, and tests on vulture carcasses in Pakistan – to pin the culprit down to diclofenac, a non-steroidal anti-inflammatory drug (NSAID) administered to cattle.
• Vultures feeding on the carcasses of animals recently treated with drug suffered renal failure that caused visceral gout and death.
• It is a fast-acting, effective painkiller and also soothes fevers. Plus, it’s cheap — costing about Rs 20, or less than half-a dollar for a dose.

There are several different types of vaccines. Each type is designed to teach your immune system how to fight off certain kinds of germs — and the serious diseases they cause. There are 4 main types of vaccines:

Live-attenuated vaccines: Live vaccines use a weakened (or attenuated) form of the germ that causes a disease.

• Because these vaccines are so similar to the natural infection that they help prevent, they create a strong and long-lasting immune response. Just 1 or 2 doses of most live vaccines can give you a lifetime of protection against a germ and the disease it causes.
• Measles, mumps, rubella (MMR combined vaccine) Varicella (chickenpox) Influenza (nasal spray) Rotavirus Yellow fever are examples of Live-attenuated vaccines.

Inactivated vaccines: use the killed version of the germ that causes a disease.

• Inactivated vaccines usually don’t provide immunity (protection) that’s as strong as live vaccines.
• So you may need several doses over time (booster shots) in order to get ongoing immunity against diseases. Polio (IPV) Hepatitis A Rabies is examples of In-activated vaccines.

Subunit, recombinant, polysaccharide, and conjugate vaccines: use specific pieces of the germ — like its protein, sugar, or capsid (a casing around the germ).

• Because these vaccines use only specific pieces of the germ, they give a very strong immune response that’s targeted to key parts of the germ.
• They can also be used on almost everyone who needs them, including people with weakened immune systems and long-term health problems.
• Hepatitis B, Influenza (injection), Haemophilus influenza type b (Hib), Pertussis (part of DTaP combined immunization), Pneumococcal, Meningococcal and Human papillomavirus (HPV) are examples of Subunit and recombinant vaccines.

Toxoid vaccines use a toxin (harmful product) made by the germ that causes a disease.

• They create immunity to the parts of the germ that cause a disease instead of the germ itself.
• That means the immune response is targeted to the toxin instead of the whole germ.
• Diphtheria, tetanus (part of DTaP combined immunization) are examples of Toxoid vaccines.

Aerosols are minute particles suspended in the atmosphere. When these particles are sufficiently large, we notice their presence as they scatter and absorb sunlight.

• Their scattering of sunlight can reduce visibility (haze) and redden sunrises and sunsets. Aerosols interact both directly and indirectly with the Earth’s radiation budget and climate.
• As a direct effect, the aerosols scatter sunlight directly back into space.
• As an indirect effect, aerosols in the lower atmosphere can modify the size of cloud particles, changing how the clouds reflect and absorb sunlight, thereby affecting the Earth’s energy budget
• Aerosols come from both natural and human sources—and sometimes both at once. Dust, for example, is scoured from deserts, the dried-out edges of rivers, dry lakebeds, and more.
• Its concentrations in the atmosphere rise and fall with climate; in cold, dry, periods in the planet‘s history like the last ice age, more dust filled the atmosphere than during warmer stretches of Earth‘s history.

A nucleotide is an organic molecule that is the building block of DNA and RNA.

• They also have functions related to cell signaling, metabolism, and enzyme reactions.
• A nucleotide is made up of three parts: a phosphate group, a 5-carbon sugar, and a nitrogenous base.
• The four nitrogenous bases in DNA are adenine, cytosine, guanine, and thymine.
• RNA contains uracil, instead of thymine.
• A nucleotide within a chain makes up the genetic material of all known living things.
• They also serve a number of functions outside of genetic information storage, as messengers and energy moving molecules.

In recent years, fundamental research has focused increasingly on the short and long term effects of CO2 injection into reservoirs to assess the feasibility of CO2 storage on a commercial scale.

• Sequestration processes involve different trapping mechanisms according to the hydrodynamic, physical and chemical conditions in the formation.
• It is common to divide these mechanisms into four different categories: hydrodynamic trapping, residual trapping, solubility trapping, and mineral trapping.

A composite material is a combination of two materials with different physical and chemical properties.

• When they are combined they create a material which is specialised to do a certain job, for instance to become stronger, lighter or resistant to electricity.
• They can also improve strength and stiffness.
• The reason for their use over traditional materials is because they improve the properties of their base materials and are applicable in many situations.
• Use of composite materials in indigenously developed aircraft (Tejas), missiles (Agni) and in defense and civilian sectors is poised for big growth, where Indian companies are set to get into manufacturing mode.

Proton, neutron, and electron are tiny particles that make up atoms.

• The neutrino is  a tiny elementary particle, but it is not part of the atom. Such particles are also found to exist in nature.
• Neutrino has a very tiny mass and no charge. It interacts very weakly with other matter particles.
• So weakly that every second trillions of neutrinos fall on us and pass through our bodies unnoticed.
• Neutrinos come from the sun (solar neutrinos) and other stars, cosmic rays that come from beyond the solar system, and from the Big Bang from which our Universe originated.
• They can also be produced in the lab.