This usually indicates a failure of the backlight inverter. If you shine a very bright flashlight on the screen and can see a recognizable pattern like the OS desktop, that is almost certainly the case. If you are handy and it is an ordinary laptop, you can usually get the part on eBay and swap it out yourself.
Fra Angelico was an early Italian Renaissance artist and a monk, considered to be one of the most talented fresco painters of his time. He was born Guido di Pietro in approximately 1395 at Rupecanina in Mugello, but nothing is known of his parents.
On Leon Battista Alberti's De re aedificatoria. Leon Battista Alberti (1404-1472) was the prototype of the Renaissance universal man, combining the vocations of humanist, athlete, engineer, architect, courtier, musician, and mathematician. A clear synthesis of so many skills is to be found in De re aedificatoria (1452), a work which became the basic text of Renaissance architecture. Alberti blends insights gained from long study of classical sources and models, such as Vitruvius, with an innovative architectural technique based upon mathematical principles and musical harmonies.