Milky Way — the galaxy — not snack-sized anymore

for more info: http://news.yahoo.com/s/ap/20090106/ap_on_sc/sci_milky_way

Deaf cats draw a blanc

Black cats have a reputation for bad omens, that's hocus-pocus and hard to prove. But white cats also present a riddle that Dr Karl found easier to solve.

By Karl S. Kruszelnicki

We humans have been domesticating cats for at least 10,000 years.

Cats are often admired for their lovely coats, and while most of today's 600 million domesticated cats have a dark coat, about 5 per cent of them have a white coat.

Now it is often believed that all white cats are deaf. The truth about white cats being deaf is that some are deaf, and some are not, kind of depending on their eye colour. But uncovering this truth has taught us much about genetics and biochemistry.

Back in 1859, Darwin wrote his revolutionary Origin of Species. This modest tome was just the short version, the summary.

Darwin spent several more years expanding his ideas and in 1868 released his two-volume big version, called The Variation Of Animals and Plants Under Domestication. What a title!

In this bigger book, he wrote that: "White cats, if they have blue eyes, are almost always deaf". Over the years, various scientists have tried to understand why.

By 1934, some very interesting studies had looked at white cats that had different coloured eyes. They found that these cats were deaf on the side with the blue eye, and had normal hearing on the side with the yellow-green eye.

What was going on? Why should white fur and a blue eye sometimes lead to deafness?

To understand what is going on, we need a little biochemistry.

Back in medical school, my favourite amino acid was tyrosine. Like the other 19 amino acids, it is used by the body as a building block to make general proteins.

But the body also has a special use for tyrosine. It modifies tyrosine to make some wonderful and special chemicals such as adrenalin, thyroid hormones, brain neurotransmitters such as DOPA, and the amazing and still mysterious melanin.

There are at least three different varieties of melanin. They can be black, dark brown or dark red in colour.

It turns out that melanin gives your skin and hair its various colours, but it does other stuff as well — it helps dampen unwanted acoustic waves in the ear to improve your hearing, it protects you from skin cancer due to UV light, and has many other protective functions.

Getting back to melanin being a colouring dye, if there's no melanin in a cat's fur, then it has a white coat. And if there's very little melanin in the iris of its eyes, then it has blue eyes.

Just as an aside, the different colours in the iris do not come from the many different coloured dyes. No, there is only one dye — melanin. If you have lots of melanin particles your iris is dark, fewer melanin particles give a green tinge, while very little melanin gives blue eyes.

So we know that white cats with blue eyes are like this because of low melanin levels in different parts of their bodies — but how is this related to deafness?

The answer lies in embryology. At conception, an egg meets up with a sperm. Shortly afterwards, the fertilized egg splits and splits again, and soon develops three separate sets of stem cells.

One, the endoderm, eventually turns into your gut and other tissues.

Another, the mesoderm, eventually turns into your skeletal muscle and other tissues.

But the third one, the ectoderm, turns into the central nervous system which includes your hearing and your sight, and — wait for it — pigment cells.

That common origin is the connection between hearing and pigments.

It seems that in our deaf, blue-eyed, white-furred cats there is a developmental fault in the ectoderm. This unknown fault is the link between the white coat and blue eyes (which is related to the low melanin from pigment cells) and deafness (which is related to the central nervous system).

However, because there are many genes involved, not all white, blue-eyed cats are deaf.

About 30 per cent of white cats have blue eyes, and about 70 per cent of these are deaf. And of the white cats that do not have blue eyes, about 15 per cent are deaf.

So white cats with blue eyes are quite likely to be deaf, but not all are. So next time you say: "Here kitty, kitty" to a white cat, don't be disappointed if it 'blancs' you.

http://www.abc.net.au/science/articles/2008/11/11/2416286.htm?site=science/greatmomentsinscience&topic=latest

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Surviving Tips to an Earthquake

 Earthquakes are natural phenomenons that cause vibration and shaking at the earth’s surface.  They can cause damage to property and infrastructure: cause fires, landslides, tsunamis and deaths. Unlike other natural events, like hurricanes and thunderstorms, earthquakes are unpredictable. The first indication of an earthquake may be a sudden violent jolt and a shaking and moving of objects. Earthquakes are a particular concern for schools with their large concentrations of children in confined spaces. To minimize the risks we need to be prepared. Preparations will include reducing hazards, being aware of places in the classroom that are deemed safe to be in when earthquakes occur and practicing the Drop, Cover and Hold On Method recommended by the American Red Cross.

Before the Earthquake: Reducing Hazards

• Identify the items that can cause injury and damage and try to fix them up. Anything that can move, fall, break or cause a fire is a potential hazard.
• Fasten shelves and bookcases securely.
• Place large, heavy objects on lower shelves.
• Hang mirrors and pictures with heavy frames away from students’ desks.
• Report cracks in ceilings or foundations and be sure they were mended.
• Store flammable products like paints, away from heat sources
• Arrange the students’ desks as far as you can from glass windows, bookcases and shelves.
• Appoint two students monitors in case you are injured
• Prepare class lists and identification tags with name, address, phone number, age, and medic alert information.
• The noises of building movement, windows breaking, and objects falling, that accompany an earthquake, can cause emotional stress and panic. Students should be prepared for this by classroom discussion.
• Practice the Drop, Cover and Hold on Method at least two times during the year. The point of this procedure is to take cover immediately in the closest safe place during the shaking of an earthquake.

     The Drop, Cover and Hold on Method consists of three steps:

1.      Drop to the floor and get under a table or desk

2.      Cover yourself by positioning as much of your body as possible under the table or desk. Protect your eyes by leaning your face against an arm.

3.      Hold on to a leg of the table or desk.

If you cannot get under a desk or table, go to the nearest wall of the room away from windows and bookcases. Kneel with back to wall. Place head close to knees, clasp hands behind neck, and cover side of head with arms. The American Red Cross does not recommend using a doorway for earthquake protection. In addition, the Red Cross strongly advises not try to move (that is, escape) during the shaking of an earthquake. The more and the longer distance that someone tries to move, the more likely they are to become injured by falling or flying debris, or by tripping, falling, or getting cut by damage floors, walls, and items in the path of escape. Exit only after shaking has stopped.

Did you know that a woman named Mary Anderson
invented the windshield wiper?