Photo quality, resolution, dpi/ppi

I was working on poster for our living room. So I needed to find out if photos I downloaded from internet was good enough for printing.

There are two units of measurements for photo quality. DPI (dots per inch) and PPI (pixels per inch). DPI is usually used for printing devices and PPI is used for imaging devices such as cameras and scanners. As picture editing softwares usually use PPI, I'll use it.

As I've mentioned PPI gives you there are how many picture cells in the inch of a photo. And for a good quality print it should be 300 ppi. If you right click to an image file and open it's properties you will see that dimensions are given in pixels. So consider you have a picture with dimensions 3216x2163 pixels.

If we divide this dimensions by 300, we will find the optimal printing size for this picture, which is 10,7x7,1 inch or 27x18 centimeters. Now we know that if we would like to have a print out of this photo to an A3 size paper, the end result will be a poor.

Swedish Matches

We used to have KAV matches. They were acquired by the company Swedish Match in 2000. When I searched I found out that Sweden is an important supplier in match market.Their comparative advantage comes from their ease of access to raw Forests consists of %60 of Sweden's area. But the advantage is not coming from wood but from phosphorus.

Phosphorus is first produced in 1675 in Germany. But the production process was extremely hard. Henning Brand, a German inventor who was trying to produce gold from human urine. During process he accidentally produced a substance which is illuminating and burn spontaneously when exposed to air. Phosphorus's name comes from Latin, which means "the bearer of light". But the production cost of phosphorus with this method was extremely high. It was costing 500 USD to produce 30 grams of Phosphorus, which make commercial production impossible.

Then in 1750's a Swedish chemist, Karl Scheele, invented a method to produce phosphorus without human urine. But there were two other contributions were needed for commercial production. First came from Gustaf Erik Pasch, who formulate a way to change yellow phosphorus, which is dangerous to human health and extremely flammable, to red phosphorus. The later substance's flammability could be controlled. Another Swedish engineer, Alexander Lagerman invented a machine which allows mass production of matches.

So with the contribution of three science people, Sweden has an important role in World's match production.

World's biggest disco ball

Most probably his friends mocked Michel de Broin, when he told them he would make biggest disco ball in the earth and he will display it in the skies of Paris. But he made it. He used 1000 mirrors to build a disco ball with 7.5 meter diameter. Then he used a crane to display his masterpiece at 50 meters above Luxembourg gardens of Paris.

Other photos could be seen in the following link...

Rains of April

In Anatolia, people usually collect rain water during April. There is even an "April Bowl" in the grave of Mevlana to collect rain waters in April.

During April, with the beginning of spring, all the pollens, resins from the flowers and trees blend to atmosphere. And rain waters will naturally includes these materials. That's why it is believed to be healthy to drink or use these waters for bathing. But for the areas of high air pollution the situation is totally opposite.

Black Tea v.s. Green Tea

Drinking tea is a very common habit in my country. People usually prefer black tea. I was curios what is the difference between them.

First of all, raw material for both green and black tea is same; leaf of tea plant. But there is a slight difference in production process. Tea production has four phases; first drying, rolling, fermentation and second drying. If leaves would undergo all these four phases, they end up as black tea. But if they are not fermented the final product is green tea. During fermentation leaves are blacken and this is what creates the typical flavor of the tea.

Green tea is claimed to be healthier because during fermentation ECGg, a very powerful antioxidant which is very rich in tea leaves, is broken down by the enzymes.

Echolocation

Echolocation is used by dolphins and bats to find their way. They use high frequency sound and its reflection to image the environment.

In a previous episode of criminal minds, I learned that very same technique is also being used by some blind people. To make such a sound, they  push their tongue to their palate and pull it back swiftly. Frequency of this sound can not be compared to those of dolphins and bats but it has a high frequency. After some training, people can understand place, dimension and density of objects around them with the echo of this sound.