Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.

Input: Consider Input: People have been using sound to make music for thousands of years. They have invented many different kinds of musical instruments for this purpose. Despite their diversity, however, musical instruments share certain similarities. All musical instruments create sound by causing matter to vibrate. The vibrations start sound waves moving through the air. Most musical instruments use resonance to amplify the sound waves and make the sounds louder. Resonance occurs when an object vibrates in response to sound waves of a certain frequency. In a musical instrument such as a guitar, the whole instrument and the air inside it may vibrate when a single string is plucked. This causes constructive interference with the sound waves, which increases their amplitude. Most musical instruments have a way of changing the frequency of the sound waves they produce. This changes the pitch of the sounds. There are three basic categories of musical instruments: percussion, wind, and stringed instruments. In Figure Researchers at Lawrence Berkeley National Laboratory are pioneering a new way to recover 100-year-old record- ings. Found on fragile wax cylinders and early lacquer records, the sounds reveal a rich acoustic heritage, including languages long lost. For more information on how to recover recordings, see [Link] MEDIA Click image to the left or use the URL below. URL: Ultrasound has frequencies higher than the human ear can detect (higher than 20,000 hertz). Although we cant hear ultrasound, it is very useful. Uses include echolocation, sonar, and ultrasonography. Animals such as bats, whales, and dolphins send out ultrasound waves and use their echoes, or reflected waves, to identify the locations of objects they cannot see. This is called echolocation. Animals use echolocation to find prey and avoid running into objects in the dark. Figure 20.13 and the animation at the URL below show how a bat uses echolocation to locate insect prey. Sonar uses ultrasound in a way that is similar to echolocation. Sonar stands for sound navigation and ranging. It is used to locate underwater objects such as sunken ships or to determine how deep the water is. A sonar device is usually located on a boat at the surface of the water. The device is both a sender and a receiver (see Figure 20.14). It sends out ultrasound waves and detects reflected waves that bounce off underwater objects or the bottom of the water. If you watch the video at the URL below, you can see how sonar is used on a submarine. The distance to underwater objects or the bottom of the water can be calculated from the known speed of sound in water and the time it takes for the waves to travel to the object. The equation for the calculation is: Distance = Speed Time Assume, for example, that a sonar device on a ship sends an ultrasound wave to the bottom of the ocean. The speed of the sound through ocean water is 1437 m/s, and the wave travels to the bottom and back in 2 seconds. What is the distance from the surface to the bottom of the water? The sound wave travels to the bottom and back in 2 seconds, so it travels from the surface to the bottom in 1 second. Therefore, the distance from the surface to the bottom is: Distance = 1437 m/s 1 s = 1437 m You Try It! Problem: The sonar device on a ship sends an ultrasound wave to the bottom of the water at speed of 1437 m/s. The wave is reflected back to the device in 4 seconds. How deep is the water? Ultrasound can be used to "see" inside the human body. This use of ultrasound is called ultrasonography. Harmless ultrasound waves are sent inside the body, and the reflected waves are used to create an image on a screen. This technology is used to examine internal organs and unborn babies without risk to the patient. You can see an ultrasound image in Figure 20.15. You can see an animation showing how ultrasonography works at this URL: In this QUEST web extra, Stanford University astrophysicist Todd Hoeksema explains how solar sound waves are a vital ingredient to the science of helioseismology, in which the interior properties of the sun

Output: use of ultrasound to locate underwater objects


Input: Consider Input: The SWR1 complex (SWR1C) in yeast catalyzes the replacement of nucleosomal H2A with the H2AZ variant, which ensures full activation of underlying genes. We compared the phenotype of mutants in the homologs of SWR1C components in Arabidopsis thaliana. Mutations in Arabidopsis SWC6 (AtSWC6), SUPPRESSOR OF FRIGIDA 3 (SUF3) and PHOTOPERIOD-INDEPENDENT EARLY FLOWERING 1 (PIE1), homologs of SWC6, ARP6 and SWR1, respectively, caused similar developmental defects, including leaf serration, weak apical dominance, flowers with extra petals and early flowering by reduction in expression of FLOWERING LOCUS C (FLC), a strong floral repressor. Chromatin immunoprecipitation assays showed that AtSWC6 and SUF3 bind to the proximal region of the FLC promoter, and protoplast transfection assays showed that AtSWC6 colocalizes with SUF3. Protein interaction analyses suggested the formation of a complex between PIE1, SUF3, AtSWC6 and AtSWC2. In addition, H2AZ, a substrate of SWR1C, interacts with both PIE1 and AtSWC2. Finally, knockdown of the H2AZ genes by RNA interference or artificial microRNA caused a phenotype similar to that of atswc6 or suf3. Our results strongly support the presence of an SWR1C-like complex in Arabidopsis that ensures proper development, including floral repression through full activation of FLC.

Output: Which protein mediates the replacement of H2A by H2A.Z in the yeast Saccharomyces cerevisiae?


Input: Consider Input: Nitric oxide (NO) is involved in many pathological conditions including neurodegenerative disorders. We have previously found that sodium nitroprusside (SNP), an NO donor, stimulates mitogen-activated protein kinases (MAPKs) such as extracellular signal-regulating kinase (ERK), c-jun N-terminal protein kinase (JNK) and p38 MAPK, leading to caspase-independent apoptosis in cultured astrocytes. In view of the previous observation that NO stimulates the activity of the Na(+)/Ca(2+) exchanger (NCX), this study examines the involvement of NCX in cytotoxicity. The specific NCX inhibitor SEA0400 blocked SNP-induced phosphorylation of ERK, JNK and p38 MAPK, and decrease in cell viability. SNP-induced phosphorylation of ERK, JNK and p38 MAPK was blocked by removal of external Ca(2+), and SNP treatment caused an increase in (45)Ca(2+) influx. This increase in (45)Ca(2+) influx was blocked by SEA0400, but not the Ca(2+) channel blocker nifedipine. In addition, SNP-induced (45)Ca(2+) influx and cytotoxicity were reduced in NCX1-deficient cells which were transfected with NCX1 siRNA. Inhibitors of intracellular Ca(2+)-dependent proteins such as calpain and calmodulin blocked SNP-induced ERK phosphorylation and decrease in cell viability. Furthermore, the guanylate cyclase inhibitor LY83583 and the cGMP-dependent protein kinase inhibitor KT5823 blocked SNP-induced cytotoxicity. These findings suggest that NCX-mediated Ca(2+) influx triggers SNP-induced apoptosis in astrocytes, which may be mediated by a cGMP-dependent pathway.


Output: The small molecule SEA0400 is an inhibitor of which ion antiporter/exchanger?