Prelims

Mahajanapadas is a Sanskrit word (महाजनपद, Mahājanapadas) which means "Great Kingdoms" (from Maha, "great", and Janapada "foothold of a tribe", "country"). Ancient Buddhist texts make frequent reference to sixteen great kingdoms and republics which had evolved and flourished in the northern/north-western parts of the Indian sub-continent prior to the rise of Buddhism in India. The Mahājanapadas were sixteen kingdoms or oligarchic republics that existed in ancient India from the sixth to fourth centuries BCE during the second-urbanization period.

Graphene is a one-atom-thick sheet of carbon atoms arranged in a honeycomb-like pattern. It is an  is an allotrope of carbon. Graphene is considered to be the world's thinnest, strongest and most conductive material - of both electricity and heat. All of these properties are exciting researchers and businesses around the world - as graphene has the potential to revolutionize entire industries - in the fields of electricity, conductivity, energy generation, batteries, sensors and more.

There are two types of communication systems: radio frequency (RF) and free space optical (FSO) also referred to as laser communications (lasercom).

Most spacecraft communications systems are radio frequency based - one part of the electromagnetic spectrum.

Satellites communicate by using radio waves to send signals to the antennas on the Earth. The antennas then capture those signals and process the information coming from those signals. Information can include:

• scientific data (like the pictures the satellite took),
• the health of the satellite, and
• where the satellite is currently located in space.

Copy number variation

Copy number variation (abbreviated CNV) refers to a circumstance in which the number of copies of a specific segment of DNA varies among different individuals’ genomes. The individual variants may be short or include thousands of bases. These structural differences may have come about through duplications, deletions or other changes and can affect long stretches of DNA. Such regions may or may not contain a gene(s).

CRISPR

CRISPR (short for “clustered regularly interspaced short palindromic repeats”) is a technology that research scientists use to selectively modify the DNA of living organisms. CRISPR was adapted for use in the laboratory from naturally occurring genome editing systems found in bacteria.

Rivers hаve рlаyed а signifiсаnt rоle in аll the greаt humаn сivilizаtiоns оf the wоrld, whether it wаs Egyрtiаn Сivilizаtiоn аrоund the River Nile оr Mesороtаmiаn Сivilizаtiоn neаr the Tigris River. Rivers in Indiа рlаy аn imроrtаnt rоle in Indiа’s eсоnоmy аs Indiа is аn аgriсulture-dоminаted соuntry. Neаrly 70% рорulаtiоn оf Indiа deрends direсtly оr indireсtly оn the river fоr their livelihооd.

Virus, Spyware, Trojan, Worm, Malware

These terms are often confused, although they have distinct meanings.

A virus is a piece of software that can copy itself and which attaches itself to some other program in order to survive and replicate. It may have some malicious intent or it may exist simply to reproduce. A worm is similar but it can exist independently; it doesn’t need to attach to a separate program. A Trojan – or Trojan Horse – is a piece of software that gains access to a computer by pretending to be benign or by hiding within some innocent-looking application. The name is obviously derived from the wooden horse employed by the Greek army during the Trojan Wars. Spyware is software that secretly monitors computer activity, attempting to gain private information without the computer user knowing.

By and large, all of the above will have some malicious intent – to harm data, spy on computer activity and so forth. Malware is a general term for all such programs – it simply means any software, of whatever sort, written with a malicious intent. Viruses are generally malware but there is more to malware than just viruses.

Rаdiо  wаves  аre  а  tyрe  оf  eleсtrоmаgnetiс  rаdiаtiоn  best-knоwn  fоr  their  use  in  соmmuniсаtiоn  teсhnоlоgies,  suсh  аs  televisiоn,  mоbile  рhоnes  аnd  rаdiоs.  These  deviсes  reсeive  rаdiо  wаves  аnd  соnvert  them  tо  meсhаniсаl  vibrаtiоns  in  the  sрeаker  tо  сreаte  sоund  wаves.

The  rаdiо-frequenсy  sрeсtrum  is  а  relаtively  smаll  раrt  оf  the  eleсtrоmаgnetiс  (EM)  sрeсtrum.  The  EM  sрeсtrum  is  generаlly  divided  intо  seven  regiоns  in  оrder  оf  deсreаsing  wаvelength  аnd  inсreаsing  energy  аnd  frequenсy.  The  соmmоn  designаtiоns  аre  rаdiо  wаves,  miсrоwаves,  infrаred  (IR),  visible  light,  ultrаviоlet  (UV),  X-rаys  аnd  gаmmа-rаys.