Society and Social sciences

A new kind of camera, which allows you to take the photo now, and focus later at any point you like. There is demo in the web.

The principle is that, you record not the sum of all the light cones, but the individual light ray's vector direction. So that you can focus to any plane by ray tracing method.

44 Challenging problems. Many are quite difficult, and tests if your physics understand is solid enough!

If you are using Joomla Php on a share host, it is likely that you cannot access the Apache log file. And it will lead to some very difficult to detect problem in your website. Using the method in this website helps you easily solve the problem by logging all the error in the error log file that you can specific the path.

You may have heard a saying that any paper cannot be folded more than 7 times. This video shows that it is possible. In fact, you can fold 11 times! But the paper they are using is as large as a football field, while the original saying is that, you can't fold an A4 paper more than 7 times. It is still an interesting video to watch.

This is a tutorial on arXiv about how negative refractive index emerges.

Best practice advice on coding style to make your Django development more smooth while achieving high quality.

If you think you can get good result for your exam, you may bet on it with Ultrinsic.

Scientists now attach probes into a living cells, and measure electrical currents from inside.

Stocks are no longer mirrors of national economies; they are not — as is so commonly said — magical forecasting mechanisms. They are small slices of ownership in specific companies, and today, those companies have less connection to any one national economy than ever before.