In Focus

Running water:

1. Where do rivers start?
2. What are spits?
3. Why do waterfalls occur?
4. What are tributary rivers?
5. What is a Baymouth Bar?

Heart and blood:

1. What is plasma?
2. How much blood do we have?
3. What are blood groups?
4. How often does the heart beat?
5. What is the heart made of?

Galaxies:

1. What is a galaxy?
2. What are double stars?
3. What is a spiral galaxy?
4. How many galaxies are there?
5. What is the Milky Way?

[Answers]

Running water:

1. Some rivers start at springs where ground water reaches the surface. There are rivers that start at the ends of melting glaciers and others at outlets of lakes.

2. Waves and currents transport sediments along coasts. In places where the coasts change direction, the worn sand and pebbles pile up in narrow ridges. These ridges are called spits.

3. When rivers cross hard rocks, waterfalls can occur. When softer rocks downstream are worn away, the hard rocks form a ledge over which the river plunges in a waterfall.

4. Rivers that flow into a main river are called tributary rivers. This swells the amount of water in the main river and increases its load of worn material.

5. When spits join one headland to another they are called baymouth bars. They can cut off bays from the sea, turning them into lagoons.

Heart and blood:

1. The yellowish liquid which comprises half of the blood in our bodies is called plasma. It is mainly water with molecules of digested food and essential salts dissolved in it.

2. An average man has 5 to 6 litres of blood while an average woman has between 4 to 5 litres. Children have less, depending on how tall or heavy they are.

3. The blood in our bodies is put into four main groups: A, B, AB and O. Out of these, only some groups can be mixed with others. So, during a medical emergency, doctors find out which blood group a patient belongs to, before giving blood transfusion.

4. The heart beats 70 times per minute in an adult and about 80 times per minute in a child. When we engage in some strenuous activity, such as dancing, running or cycling, it beats faster than normal. This is to send more blood to the muscles.

5. The heart is made of a special kind of a muscle known as the cardiac (heart) muscle which never gets tired.

Galaxies:

1. Our Sun is just one of the massive collection of 200 billion stars arranged in a shape like a fried egg, about 100,000 light years across. This collection is called the Galaxy because we see it in the band of stars across the night sky known as the Milky Way. Galaxy comes from the Greek word for ‘milky.’ Earlier this century, it was realised that the Galaxy is just one of billions of similar giant star groups scattered throughout space, which we also call Galaxies. The nearest such Galaxy is Andromedia.

2. Double stars are called binaries. Our Sun however is a lone star but many stars have one or more nearby companions.

3. A Galaxy that has spiralling arms of stars like a gigantic Catherine Wheel is called a spiral Galaxy. They (the stars) trail because the Galaxy is rotating. Our Galaxy is spiral.

4. Currently there are estimated to be about 125 billion Galaxies in the universe - there may be many more.

5. The pale, blotchy white band that stretches right across the night sky is called the Milky Way. From Earth we get only an edge-on view of it. A powerful telescope shows that it is made up of millions of stars.

Method to warn of earthquakes discovered?

Researchers the world over are seeking reliable ways to predict earthquakes, focusing on identifying seismic precursors that, if detected early enough, could serve as early warnings.

New research, published this week in the journal Applied Physics Letters, suggests that ozone gas emitted from fracturing rocks could serve as an indicator of impending earthquakes. Ozone is a natural gas, a byproduct of electrical discharges into the air from several sources, such as from lightning, or, according to the new research, from rocks breaking under pressure.

Scientists in the lab of Raul A. Baragiola, a professor of engineering physics in the University of Virginia School of Engineering and Applied Science set up experiments to measure ozone produced by crushing or drilling into different igneous and metamorphic rocks, including granite, basalt, gneiss, rhyolite and quartz. Different rocks produced different amounts of ozone, with rhyolite producing the strongest ozone emission.

Some time prior to an earthquake, pressures begin to build in underground faults. These pressures fracture rocks, and presumably, would produce detectable ozone.

To distinguish whether the ozone was coming from the rocks or from reactions in the atmosphere, the researchers conducted experiments in pure oxygen, nitrogen, helium and carbon dioxide.

They found that ozone was produced by fracturing rocks only in conditions containing oxygen atoms, such as air, carbon dioxide and pure oxygen molecules, indicating that it came from reactions in the gas.

This suggests that rock fractures may be detectable by measuring ozone.Baragiola began the study by wondering if animals, which seem “at least anecdotally” to be capable of anticipating earthquakes, may be sensitive to changing levels of ozone, and therefore able to react in advance to an earthquake.

It occurred to him that if fracturing rocks create ozone, then ozone detectors might be used as warning devices in the same way that animal behavioral changes might be indicators of seismic activity.

He said the research has several implications.

"If future research shows a positive correlation between ground-level ozone near geological faults and earthquakes, an array of interconnected ozone detectors could monitor anomalous patterns when rock fracture induces the release of ozone from underground and surface cracks," he said."Such an array, located away from areas with high levels of ground ozone, could be useful for giving early warning to earthquakes."

He added that detection of an increase of ground ozone might also be useful in anticipating disasters in tunnel excavation, landslides and underground mines.

- ScienceDaily