kukuruku
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kukuruku

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Web Development →

IT digest for the last week

Web Development



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UI →

Why is the mouse cursor slightly tilted and not straight?

One of the users of StackExchange asked a question, which at first glance may look weird: why is the mouse cursor slightly tilted and not straight? Indeed, why the cursor is not vertical?

Vertical mouse cursor

The answer was given by an expert, who is familiar with the history of computer hardware. He confirms, that initially the mouse and therefore the mouse cursor invented by Douglas Engelbart, was an arrow pointing up.

However, graphical interface for the first operating system in the world was designed by Xerox, precisely — the Palo Alto Research Center. The mouse cursor was described in a document, which lists all of the specifications of XEROX PARC, the first computer with graphical user interface. It was found that, given the low resolution of the screens in those days, drawing a straight line (left edge of arrow) and a line at a 45 degree angle (right edge of arrow) was easier to do and more recognizable than the straight cursor.

Palo Alto Research Center

These days, the tradition is being kept alive despite high-resolution displays we have and huge technological progress in general.
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DIY →

At Stanford University a paper microscope has been developed that costs less than a dollar

The main motive for the creation of the microscope was the struggle against malaria — in the developing countries about a billion microscopic examinations of the blood samples per year have to be carried out for malaria diagnosis. A standard laboratory microscope is an expensive and fragile device. Stanford scientists have managed to construct a microscope with magnification up to the 2000x, while the cost of all the components in a mass production will be 97 cents. The microscope body is cut out and folded from a sheet of thick paper. Other components are a flat battery, a LED switch, a piece of conductive copper tape and a glass or a sapphire ball lens.

Paper microscope fits easily in your one's pocket, weighs less than ten grams, can be used for brightfield, darkfield, polarized and fluorescent microscopy, and even work as a projector. One battery lasts for 50 hours. Microscope can easily endure pretty rough usage, it can even be stepped on, it can be dropped on the floor — it can withstand anything that a piece of cardboard can withstand. The quality of the microscope image is sufficient to determine various types of infections in outdoor conditions.

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