google.com, pub-9220471781781135, DIRECT, f08c47fec0942fa0 Several tips: September 2017

Monday, September 18, 2017

Radiation and Life

Radiation and Life - World Nuclear Association

"Life on earth has developed with an ever present background of radiation. It is not something new, invented by the wit of man: radiation has always been there."
-Eric J Hall, Professor of Radiology, College of Physicians and Surgeons, Columbia University, New York, in his book "Radiation and Life".

Contents: Unstable Atoms, Atomic Decay, Half-life, Types of Ionizing radiation, Measuring Ionizing Radiation, What are the health risks from ionizing radiation?, Man-made Radiation, Protection from Radiation, Standards and Regulations, Understanding Radiation, Related Information.

Wednesday, September 6, 2017

How do Corals Reproduce?

Corals can reproduce asexually and sexually. Coral reproductive methods vary according to the species. Some species, such as brain and star corals, are hermaphrodites, meaning they produce both sperm and eggs at the same time. Other corals, such as elkhorn and boulder corals, are gonochoric, meaning that they produce single-sex colonies. In these species, all of the polyps in one colony produce only sperm, and all of the polyps in another colony produce only eggs.
Coral larvae are formed in two different ways. The larvae are either fertilized within the body of a polyp or fertilized outside of the polyp’s body in the water. Fertilization of an egg within the body of a coral polyp is achieved from sperm that is released through the mouth of another polyp. The sperm and egg merge and form a planula larva, which matures inside the body of its mother. When the larva is ready, it gets spit out into the water through the mouth of its mother.
Other species of coral reproduce by ejecting large quantities of eggs and sperm into the surrounding water. When this happens, the eggs and sperm fertilize in the water. This process is called coral spawning. In some areas, mass coral spawning events occur on one particular night per year and scientists can predict exactly when this will happen. Trillions of eggs and sperm are simultaneously released into the water in one of the most astounding acts of synchronicity in the natural world!
Once in the sea, larvae are naturally attracted to the light. They swim to the surface of the ocean, where they remain for days or even weeks. If predators do not eat the larvae during this time, they fall back to the ocean floor and attach themselves to a hard surface. An attached planula metamorphasizes into a coral polyp and begins to grow—dividing itself in half and making exact genetic copies of itself. As more and more polyps are added, a coral colony develops. Eventually the coral colony becomes mature, begins reproducing, and the cycle of life continues. 

Don’t Remove Baby’s Body Hair

A new born baby may have fine and soft hair in its body. This hair is called lanugo. Many newborn babies have a lot of body hair. Body hai...