Ask Me

2022-05-07 07:30:01 What are allotransplantation and xenotransplantation?

Allotransplantation (“allo” means "other" in Greek) is the transplantation of cells, tissues, or organs to a recipient from a genetically non-identical donor of the same species. The transplant is called an allograft, allogenic transplant, or homograft, so all human tissues and organs when transplanted from one person to another are scientifically called allografts.

Allotransplantation is different to xenotransplantation (“xenos” is the Greek root meaning "foreign"), or heterologous transplant, which is the transplantation of living cells, tissues or organs, called xenografts or xenotransplants, from one species to another. For example, pigs’ heart valves transplanted into a human is a xenotranplantation.

Xenotransplantation, when human cells are implanted into animals , is a research technique frequently used by scientists in pre-clinical studies , for instance in oncology.

Subscribe- t.me/askmenow Open / Comment

2022-05-06 07:30:00 When and where was the first artificial heart successfully implanted?

In December 1982, at the University of Utah, in the US , a Seattle dentist Barney Clark became the first human to receive a permanent artificial heart, a device known as Jarvik-7.

Jarvik-7 was made of plastic and metal and intended for permanent implantation in a human being.

The engineered organ comprised two plastic pumps powered by compressed air, which required the patient to be hooked up at all times to a rolling console the size and weight of a refrigerator. It could pump blood through the body at 40 to 120 pulses per minute, but it replaced the telltale heartbeat with a soft clicking sound followed by a whoosh.

The artificial heart was designed by a team consisting of Robert Jarvik (whose name the device received), William DeVries , who performed the operation, and Willem Johan Kolff.

The patient lived for another 112 days on the mechanical organ.

Subscribe- t.me/askmenow Open / Comment

2022-05-05 15:51:58 When and where was the world's first human-to-human heart transplant operation performed?

In December 1967, at Groote Schuur Hospital in Cape Town, South Africa , a surgeon Christiaan Barnard performed the world's first human-to-human heart transplant operation.

It was 53-year-old Louis Washkansky who received the first human heart transplant from Denise Darvall, a 25-year-old woman, fatally injured in a car accident.

Washkansky’s new heart functioned normally, but 18 days after the revolutionary medical operation the man died from double pneumonia as the drugs that were given to him to suppress his immune system and keep his body from rejecting the heart left him more susceptible to sickness.

In the 1970s, the development of better anti-rejection drugs made transplantation more viable. Dr. Barnard continued to operate, and many of his patients were living up to five years with their new hearts.

Subscribe- t.me/askmenow Open / Comment

2022-05-03 07:30:00 What is a planet parade?

Although there is no scientific definition for the ‘planet parade’, it is being widely used in astronomy to denote an event that takes place when planets of the solar system are aligned in one straight line.

Another term for a planet parade is ‘appulse’.

The following types are distinguished:
Mini planet parade — planets.
Small planet parade — planets.
Large planet parade — or planets.
Great planet parade — all solar system’s planets (+ Pluto sometimes).

3 planets align on one side of the Sun simultaneously 2 times a year, 4 planets — once a year, 5 planets — once in every 19 years, and all 8 planets of the Solar system — once in about 170 years.

For inner planets, the best viewing conditions occur near their greatest elongations, and for outer planets — sometime before and after their oppositions.

In April and May 2022 several appulses, including a parade of 4 planets – Venus, Mars, Jupiter and Saturn – can be observed.

Subscribe- t.me/askmenow Open / Comment

2022-05-02 11:09:08 What are the major observational differences between stars and planets?

When the night sky is clear, one can observe plenty of tiny dots, and some of them are stars while others are planets.

These are major observational distinguishing features of planets and stars.

Twinkling.
Stars are constantly twinkling and shimmering while planets do not. Observed through a telescope, stars appear to shake around the edges.

Brightness.
Planets are typically brighter than stars. The reason for differing brightness is because planets reflect the light of the sun, which is close to our planet, while the stars emit their own light.

Shape.
Stars appear as a dot while planets appear spherical. Generally, stars are also bigger than planets.

Movement.
A planet moves across the night sky while observing the rules followed by the sun and the moon. Therefore, a celestial body appearing to move in a straight line is more likely going to be a planet. Stars move in a circular pattern.

Subscribe- t.me/askmenow Open / Comment

2022-04-28 16:41:32 What are the essential features of a planet?

A planet is a celestial body that orbits around a star.

It has an adequate mass for its own gravity to get on top of rigid body forces so that it assumes a hydrostatic equilibrium to make it round.

Planets are smaller than stars.

In our Solar System there are two categories of planets:

Inner planets, which are close to the Sun. These are Mercury, Venus, Earth , and Mars.

Outer planets, which come after an asteroid belt and are at a farther distance from the Sun. These are Jupiter, Saturn , Uranus, and Neptune.

Subscribe- t.me/askmenow Open / Comment

2022-04-27 17:35:31 What are the essential features of a star?

A star is a celestial body having its own light and energy.

A star is a huge glittering ball of hot gas, mainly consisting of Hydrogen and Helium.

Stars are giant, luminous spheres of plasma collapsed together by gravity.

Stars are responsible for the manufacture of elements like Carbon, Nitrogen, and Oxygen.

Star formation shapes the visual aspect of the universe and provides the sites for planets.

Subscribe- t.me/askmenow Open / Comment

2022-04-23 16:40:25 Subscribe- t.me/askmenow Open / Comment

2022-04-23 16:37:58 Where and why are the largest artificial waves generated?

The largest artificial waves are made in the Netherlands at the Delta Flume wave generator.

This facility, opened in 2015, has a 300 m long (984-foot) tank, which holds 9 million liters (2.4 million gallons) of water, and is capable to create waves with a maximum height of 5 m (16.4 feet).

The Delta Flume wave generator permits to test at full scale the effect of extreme waves on dikes, dunes, breakwaters and offshore structures and can be used for numerous projects: coastal, harbour and offshore structures.

It was conceived and constructed as a response to a considerable global demand for the realistic testing of hydraulic structures in particular situations.

Subscribe- t.me/askmenow Open / Comment

2022-04-22 15:50:29 What is a tidal bore?

Big waves occur not only in oceans but also in rivers.

The largest river waves are recorded during a tidal bore, that is a phenomenon in which an incoming tide reverses the current of a river and forms a wave, or waves, of water that travel up the river.

The world's largest tidal bore regularly occurs in China's Qiantang River during the eighth month of the lunar calendar .

The wave then normally reaches around 9 m (29.5 feet) high.

However, there are evidences that on Aug. 22, 2013, an additional surge from a typhoon caused the wave to reach around 20 m (65.6 feet) high and even injured 30 spectators of this remarkable natural water spectacle.

Subscribe- t.me/askmenow Open / Comment