Hepatitis – A to E

Hepatitis is an inflammation of the liver commonly caused by viral infections. but other infections, toxic substances (e.g. alcohol, certain drugs), and autoimmune diseases can also cause hepatitis. Hepatitis can be self-limiting or can progress to fibrosis (scarring), cirrhosis or liver cancer.

There are 5 main hepatitis viruses, referred to as types A, B, C, D and E. Types B and C especially lead to chronic disease in a majority of affected people and, together, are the most common cause of liver cirrhosis and cancer.

Hepatitis A and E are typically caused by ingestion of food or water contaminated by the virus from faecal matter. Hepatitis B, C and D usually occur as a result of parenteral contact (contact with infected body fluids). Common modes of transmission for these viruses include receipt of contaminated blood or blood products, invasive medical procedures using contaminated equipment and for hepatitis B transmission from mother to baby at birth, from family member to child, and also by sexual contact.

Acute infections may be asymptomatic or associated with Jaundice, Dark urine, Fatigue, Nausea and abdominal pain.

Hepatitis A Virus Infections are in many cases mild, with most people making a full recovery and remaining immune from further HAV infections. Hepatitis B Virus spreads mainly through parenteral route and as a Sexually Transmitted Disease(STD). Safe and effective vaccines are available to prevent HBV.

There is no vaccine for Hepatitis C Virus and it mainly spreads through blood and blood products. It can also be an STD, though rarely.

Hepatitis D virus infects only those people who are already affected by HBV. The dual infection of HDV and HBV can result in a more serious disease and worse outcome. Hepatitis B vaccines provide protection from HDV infection.

HEV is a common cause of hepatitis outbreaks in developing parts of the world and is increasingly recognized as an important cause of disease in developed countries. Safe and effective vaccines to prevent HEV infection have been developed but are not widely available.

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Gravitational Waves

Just like ripples in the water, there are ripples(Waves) in the space created when there is a movement of objects with mass. They are generated as a result of gravitational interaction and is propagated from their source at the speed of light. They contain energy transmitted as gravitational radiations similar to the electromagnetic radiations.

They were predicted by Albert Einstein in 1916 on the basis of his theory of general relativity.

Gravitational-wave astronomy is a branch of observational astronomy which uses gravitational waves to collect observational data about sources of detectable gravitational waves such as binary star systems composed of white dwarfs, neutron stars, and black holes; and events such as supernovae, and the formation of the early universe shortly after the Big Bang.

The LIGO and Virgo Scientific Collaboration announced that they had made the first observation of gravitational waves in 2015 September. The announcement was made in 2016. The gravity waves originated from a pair of merging black holes. The collision happened 1.3 billion years ago. But, the ripples didn’t make it to Earth until 2015. After the initial announcement, the LIGO instruments detected two more confirmed, and one potential, gravitational wave events.

The most powerful gravitational waves are created when objects move at very high speeds. Some examples of events that could cause a gravitational wave are:

  • when a star explodes asymmetrically (called a supernova)
  • when two big stars orbit each other
  • when two black holes orbit each other and merge

The types of objects that create gravitational waves are far away from earth. And sometimes, these events only cause small, weak gravitational waves. The waves are then very weak by the time they reach Earth. This makes gravitational waves hard to detect.

Two Nobels

  • In 1993, the Nobel Prize in Physics was awarded for measurements of the Hulse-Taylor binary star system that suggests gravitational waves are more than mathematical anomalies.
  • In 2017, the Nobel Prize in Physics was awarded to Rainer Weiss, Kip Thorne and Barry Barish for their role in the detection of gravitational waves


The Laser Interferometer Gravitational-Wave Observatory (LIGO) is a large-scale physics experiment and observatory to detect cosmic gravitational waves and to develop gravitational-wave observations as an astronomical tool. LIGO is made up of two observatories: one in Louisiana and one in Washington. Each observatory has two long “arms” that are each more than 2 miles (4 kilometres) long.

When a gravitational wave passes by Earth, it squeezes and stretches space. LIGO can detect this squeezing and stretching.  A passing gravitational wave causes the length of the arms to change slightly. The observatory uses lasers, mirrors, and extremely sensitive instruments to detect these tiny changes.

Before this, just about everything we knew about the universe came from studying waves of light. Now we have a new way to learn about the universe—by studying waves of gravity. Gravitational waves will help us learn many new things about our universe.

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