instruction:
Given a context passage, generate a question from the passage such that its answer is shortest continous span from the passage.
question:
To be a good aquifer, the rock in the aquifer must have good: porosity: small spaces between grains permeability: connections between pores To reach an aquifer, surface water infiltrates downward into the ground through tiny spaces or pores in the rock. The water travels down through the permeable rock until it reaches a layer that does not have pores; this rock is impermeable (Figure 1.1). This impermeable rock layer forms the base of the aquifer. The upper surface where the groundwater reaches is the water table. Groundwater is found beneath the solid surface. Notice that the water table roughly mirrors the slope of the lands surface. A well penetrates the water table. For a groundwater aquifer to contain the same amount of water, the amount of recharge must equal the amount of discharge. What are the likely sources of recharge? What are the likely sources of discharge? What happens to the water table when there is a lot of rainfall? What happens when there is a drought? Although groundwater levels do not rise and fall as rapidly as at the surface, over time the water table will rise during wet periods and fall during droughts. In wet regions, streams are fed by groundwater; the surface of the stream is the top of the water table (Figure 1.2). In dry regions, water seeps down from the stream into the aquifer. These streams are often dry much of the year. Water leaves a groundwater reservoir in streams or springs. People take water from aquifers, too. Groundwater meets the surface in a stream (Figure 1.2) or a spring (Figure 1.3). A spring may be constant, or may only flow at certain times of year. Towns in many locations depend on water from springs. Springs can be an extremely important source of water in locations where surface water is scarce. A well is created by digging or drilling to reach groundwater. It is important for anyone who intends to dig a well to know how deep beneath the surface the water table is. When the water table is close to the surface, wells are a convenient method for extracting water. When the water table is far below the surface, specialized equipment must The top of the stream is the top of the water table. The stream feeds the aquifer. A spring in Croatia bubbles to the surface and feeds the river Cetina. be used to dig a well. Most wells use motorized pumps to bring water to the surface, but some still require people to use a bucket to draw water up (Figure 1.4). An old-fashioned well that uses a bucket drawn up by hand.
answer:
the surface of a stream is


question:
Riociguat (Adempas(®)), a soluble guanylate cyclase stimulator, is a new, first-in-class drug approved for the treatment of patients with chronic thromboembolic pulmonary hypertension (CTEPH) [inoperable or persistent/recurrent following surgery] or pulmonary arterial hypertension (PAH). It has been designated an orphan medicine by the European Medicines Agency and the US FDA. This article reviews the available pharmacological properties of oral riociguat and its clinical efficacy and tolerability in adults with CTEPH or PAH. Riociguat is effective and well tolerated in patients with inoperable CTEPH or persistent/recurrent CTEPH following pulmonary endarterectomy, and in patients with PAH. It has a positive result on exercise capacity and pulmonary haemodynamics, and improves WHO functional class. Most adverse events can be attributed to the vasodilatory mechanism of riociguat; however, there is a potential for serious bleeding and fetal harm, and riociguat use is contraindicated in pregnant patients. Pulmonary endarterectomy remains the first treatment of choice for CTEPH, as it is potentially curative. Head-to-head trials comparing riociguat with the approved phosphodiesterase type 5 inhibitors in patients with PAH would be of value for the placement of riociguat in the management of this disease. Riociguat is a promising addition to the treatment options for patients with CTEPH or PAH.
answer:
What is generic name of drug Adempas?


question:
Net energy is the amount of useable energy available from a resource after subtracting the amount of energy needed to make the energy from that resource available. For example, every 5 barrels of oil that are made available for use require 1 barrel for extracting and refining the petroleum. What is the net energy from this process? About 4 barrels (5 barrels minus 1 barrel). What happens if the energy needed to extract and refine oil increases? Why might that happen? The energy cost of an energy resource increases when the easy deposits of that resource have already been consumed. For example, if all the nearshore petroleum in a region has been extracted, more costly drilling must take place further offshore (Figure 1.1). If the energy cost of obtaining energy increases, the resource will be used even faster. Offshore drilling is taking place in deeper water than before. It takes a lot of energy to build a deep drilling platform and to run it. The net-energy ratio demonstrates the difference between the amount of energy available in a resource and the amount of energy used to get it. If it takes 8 units of energy to make available 10 units of energy, then the net-energy ratio is 10/8 or 1.25. What does a net-energy ratio larger than 1 mean? What if the net-energy ratio is less than 1? A net-energy ratio larger than 1 means that there is a net gain in usable energy; a net-energy ratio smaller than one means there is an overall energy loss. Table 1.1 shows the net-energy ratios for some common energy sources. Energy Source Solar Energy Natural Gas Petroleum Coal-fired Electricity Net-energy Ratio 5.8 4.9 4.5 2.5-5.1 Notice from the table that solar energy yields much more net energy than other sources. This is because it takes very little energy to get usable solar energy. Sunshine is abundant and does not need to be found, extracted, or transported very far. The range for coal-fired electricity is because of the differing costs of transporting the coal. What does this suggest about using coal to generate electricity? The efficiency is greater in areas where the coal is locally mined and does not have to be transported great distances (Figure 1.2). Obtaining coal for energy takes a lot of energy. The coal must be located, extracted, refined, and transported. Because so much of the energy we use is from fossil fuels, we need to be especially concerned about using them efficiently. Sometimes our choices affect energy efficiency. For example, transportation by cars and airplanes is less energy-efficient than transportation by boats and trains.
answer:

what is the amount of useable energy available from a resource after subtracting the amount of energy needed to make that energy available?