Tumor

Tumor or tumour is an irregular growth or mass of tissue. A tumor can be either malignant or benign. Almost all tumors are examples of neoplasia, although certain developmental malformations or inflammatory masses may occasionally be referred to as tumors.

Neoplastic tumors are caused by mutations in DNA of cells, which interfere with a cell's capability to regulate and limit cell division. An accumulation of mutations is needed for a tumor to emerge. Mutations that activate oncogenes or repress tumor suppressor genes can eventually lead to tumors. Cells have mechanisms that repair DNA and other mechanisms that cause the cell to destroy itself by apoptosis if DNA damage gets too severe. Mutations that repress the genes for these mechanisms can also ultimately guide to cancer. A mutation in one oncogene or one tumor repressor gene is usually not enough for a tumor to occur. A combination of a number of mutations is essential.

Watch

100 A watches is a small portable clock that displays the current time and sometimes the current day, date, month and year. In modern times they are frequently worn on the wrist with a watch-strap, although before the 20th century most were pocket watches, which had covers and were carried individually, often in a pocket, and hooked to a watch chain.

Present watches are often digital watches, using a piezoelectric crystal, regularly quartz, as an oscillator.

In earlier times mechanical timepieces were used, motorized by a spring wound regularly by the user. The discovery of "Automatic" or "Self-Winding" watches allowed for a stable winding without particular action from the wearer: it works by an eccentric weight, called a winding rotor, which rotates to the movement of the wearer's body. The back-and-forth motion of the winding rotor couples to a rachet to automatically wind the watch.


Types of watch

Pocket clock
The first necessity for portability in time keeping was steering and mapping in the 15th century. The latitude could be measured by looking at the stars, but the only way a ship could measure its longitude was by comparing time zones; by comparing the noontime time of the local longitude to a European meridian, a sailor could know how far he was from home. However, the process was notoriously defective until the introduction of John Harrison's chronometer. For that reason, most maps from the 15th century to c.1800 have precise latitudes but indistinct longitudes.

The first reasonably exact mechanical clocks measured time with weighted pendulums, which are useless at sea or in watches. The creation of a spring mechanism was crucial for portable clocks. In Tudor England, the development of "pocket-clocks" was enabled through the development of reliable springs and escapement mechanisms, which allowed clockmakers to compress a timekeeping device into a small, portable compartment. In 1524, Peter Heinlein created the first pocket watch. It is supposed that Henry VIII had a pocket clock which he kept on a chain around his neck. However, these watches only had an hour hand - a minute hand would have been useless bearing in mind the inexactness of the watch mechanism. Eventually, miniaturization of these spring-based designs allowed for exact portable timepieces which worked well even at sea. Aaron Lufkin Dennison founded Waltham Watch Company in 1850, which was the pioneer of the industrial developed by interchangeable parts, the American System of Watch Manufacturing.

Salad

Salad is a light meal — or, as part of a larger meal, much more of an taster — consisting of mixed vegetables (usually including at least one leaf vegetable) or fruit, frequently with a dressing or sauce, occasionally nuts and sometimes with the addition of meat, fish or cheese. It is generally seen as a healthy dish, although not always low in calories, salt, sugar, or fat because of the dressing that is often added.The word "salad" comes from the French salade of the same meaning, which in twist is from the Latin salata, "salty", from sal, "salt".