Input: Article: Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport. The final phase is the death phase where the bacteria run out of nutrients and die.

Now answer this question: What is called the third statge of growth of bacteria?

Output: stationary phase

Input: Article: Many sensor systems rely on light as the signal source. LEDs are often ideal as a light source due to the requirements of the sensors. LEDs are used as motion sensors, for example in optical computer mice. The Nintendo Wii's sensor bar uses infrared LEDs. Pulse oximeters use them for measuring oxygen saturation. Some flatbed scanners use arrays of RGB LEDs rather than the typical cold-cathode fluorescent lamp as the light source. Having independent control of three illuminated colors allows the scanner to calibrate itself for more accurate color balance, and there is no need for warm-up. Further, its sensors only need be monochromatic, since at any one time the page being scanned is only lit by one color of light. Since LEDs can also be used as photodiodes, they can be used for both photo emission and detection. This could be used, for example, in a touchscreen that registers reflected light from a finger or stylus. Many materials and biological systems are sensitive to, or dependent on, light. Grow lights use LEDs to increase photosynthesis in plants, and bacteria and viruses can be removed from water and other substances using UV LEDs for sterilization.

Now answer this question: What device uses infrared LEDs to measure oxygen saturation?

Output: Pulse oximeters

Input: Article: The first amendment to the US Constitution states "Congress shall make no law respecting an establishment of religion, or prohibiting the free exercise thereof" The two parts, known as the "establishment clause" and the "free exercise clause" respectively, form the textual basis for the Supreme Court's interpretations of the "separation of church and state" doctrine. Three central concepts were derived from the 1st Amendment which became America's doctrine for church-state separation: no coercion in religious matters, no expectation to support a religion against one's will, and religious liberty encompasses all religions. In sum, citizens are free to embrace or reject a faith, any support for religion - financial or physical - must be voluntary, and all religions are equal in the eyes of the law with no special preference or favoritism.

Now answer this question: What are citizens of the United States free to embrace or reject as they choose?

Output:
a faith