Water requirements

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  • Water is finite on earth. There is a fixed amount of water which neither decreases or increases. Fresh water is a renewable resource because of the water cycle. From a human perspective the source of freshwater is rainfall. Most of this rainfall is used directly for vegetative growth, such as natural vegetation, pasture, rain-fed maize etc. This process, known as transpiration, is highly productive and produces in Southern Africa the bulk of food crops.

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  • Over the past 15 years, evidence has accumulated that the nation's ground water resource, which supplies more than 50 percent of the population's drinking water, is threatened not only by excessive overdrafts but also by contamination caused by past and present industrial, agricultural, and commercial activities. In the United States, it is estimated that more than 300,000 sites may have contaminated soil or ground water requiring some form of remediation (see Table 1-2 in Chapter 1).

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  • The large amount of water required for the production of plant substance is taken from the soil by the roots. Leaves and stems do not absorb appreciable quantities of water. The scanty rainfall of dry-farm districts or the more abundant precipitation of humid regions must, therefore, be made to enter the soil in such a manner as to be readily available as soil-moisture to the roots at the right periods of plant growth. In humid countries, the rain that falls during the growing season is looked upon, and very properly, as the really effective factor in the production of large...

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  • Harrison's Internal Medicine Chapter 70. Nutritional Requirements and Dietary Assessment Nutritional Requirements and Dietary Assessment: Introduction Nutrients are substances that must be supplied by the diet because they are not synthesized in the body in sufficient amounts. Nutrient requirements for groups of healthy persons have been determined experimentally. For good health we require energy-providing nutrients (protein, fat, and carbohydrate), vitamins, minerals, and water.

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  • In recent years, the awareness of water needs and processing requirement has become an increasingly important topic. As the earth's population increases the demand for "clean" water has become an even larger factor in residential as well as industrial and commercial costs. There are now almost no natural water sources that do not require some purific

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  • Hypovolemia: Treatment The therapeutic goals are to restore normovolemia with fluid similar in composition to that lost and to replace ongoing losses. Symptoms and signs, including weight loss, can help estimate the degree of volume contraction and should also be monitored to assess response to treatment. Mild volume contraction can usually be corrected via the oral route. More severe hypovolemia requires intravenous therapy. Isotonic or normal saline (0.

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  • Water For adults, 1.0–1.5 mL water per kcal of energy expenditure is sufficient under usual conditions to allow for normal variations in physical activity, sweating, and solute load of the diet. Water losses include 50–100 mL/d in the feces, 500–1000 mL/d by evaporation or exhalation, and, depending on the renal solute load, ≥1000 mL/d in the urine. If external losses increase, intakes must increase accordingly to avoid underhydration. Fever increases water losses by approximately 200 mL/d per °C; diarrheal losses vary but may be as great as 5 L/d with severe diarrhea.

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  • In order to maintain economic development and minimize future regional and international conflicts, the United States will need sustainable supplies of high-quality fresh water. Solutions to local water scarcity issues will likely require a combination of approaches, including demand management, improved water storage capacity, water quality protection, and advancements in supply-enhancing water treatment technologies. Desalination technologies can create new sources of freshwater from otherwise impaired waters such as seawater or brackish water.

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  • China faces a major challenge in managing its scarce water resources to sustain economic growth in the years ahead. This report provides an overview of China’s water scarcity situation, assesses the policy and institutional requirements for addressing it, and recommends key areas for strengthening and reform. The issues covered

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  • Physiologic Factors Growth, strenuous physical activity, pregnancy, and lactation increase needs for energy and several essential nutrients, including water. Energy needs rise during pregnancy, due to the demands of fetal growth, and during lactation, because of the increased energy required for milk production. Energy needs decrease with loss of lean body mass, the major determinant of REE. Because both health and physical activity tend to decline with age, energy needs in older persons, especially those over 70, tend to be less than those of younger persons.

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  • Water supply and sanitation are amongst the most basic requirements of life. For the past 50 to 150 years people living in Europe, America and a few capital cities elsewhere around the globe have come to take for granted the provision of a virtually limitless supply of clean, safe water and the seemingly effortless removal of all human wastes ‘out of sight and out of mind’.

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  • In 1972, the Clean Water Act (CWA) delineated the basic structure for regulating discharges of pollutants into waters and for establishing quality standards for surface waters under the authority of EPA [10]. Under the CWA’s National Pollutant Discharge Elimination System program, stormwater permits were required for sediment runoff from construction sites and discharges of pollutants into surface waters [11]. The permitting system requires adoption of technology-based and water quality-based effluent limits [11,12].

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  • More specifically, the recommended assessment should identify the occurrence (in space and time) of both surface and groundwater quantity and their associated water quality, together with a tentative assessment of trends in water requirements and water resources development (see Box 10.1). The assessment should be based, as far as possible, on existing data and knowledge in order to avoid unnecessary delays in the process of management improvement.

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  • Another aspect to take into account in assigning priority is the geographical extent of the impact, i.e. whether a particular problem, for example caused by a discharge of wastewater, has only a local impact in an area of a few hundred meters along the river or whether there is an impact in the entire river system downstream of the discharge. The likely answer depends, for example, on the size of the discharge and the retention time in the receiving water bodies, the degradability of the pollutant, and the occurrence of sensitive species in the receiving water body. In addition, the...

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  • This sustained defence concerns the physical safety of citi- zens, territory and interests, legal culture and liberty. It will be played out in many theatres, and will cover many policy domains that have traditionally been kept separate from each other. Understanding how different matters are interrelated is a very important first step in beginning to be able to address them effectively.

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  • The litho-hydrodynamic and environmental conditions in the Vietnamese coastal estuarine basin are significantly affected by the land-ocean-atmosphere interaction processes whish tide has a determining role. Application of the coupled 1D, 2D and 3D modeling system could resolve this complicated problem but it requires other solutions related with the boundary and coupling conditions.

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  • Pipe stress analysis calculates the stress in a piping system subject to normal operating loads such as pressure, weight, and thermal expansion, and occasional loads such as wind, earthquake, and water hammer. Because all piping systems are connected to equipment such as vessels, tanks, pumps, turbines, and compressors, the piping stress analysis also involves evaluation of the effect of the piping forces and moments to the connecting equipment. As the piping stress is controlled by the arrangement of the supports and restraints, the scope of piping stress includes also pipe supports.

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  • Amidst the many advantages of gas turbine (GT) combined cycles (CC) popular today from various standpoints (lower investment than for new greenfield plants, reduced environmental impact, and faster installation and startup), one drawback is that the achievable output decreases significantly as the ambient inlet air temperature increases. The lower density of warm air reduces mass flow through the GT. And, unfortunately, hot weather typically corresponds to peak power loads in many areas. So the need to meet peak-load and power-sales contract requirements causes many ...

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  • This document should be useful for security program managers, technical and functional managers, network and system administrators, and other information technology (IT) staff members. It provides them with a structured approach to network security testing. Management personnel who are responsible for systems can apply the testing procedures and tools discussed in this document to become informed about the status of the assets under their stewardship. This document can also assist in evaluating compliance with their organization’s security standards and requirements.

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  • Welcome to the discipline of building services engineering. You will find that it extends beyond the confines of this text, which concentrates on some of the ‘wet services’ within the building envelope. Part of Chapter 1, however, looks at the building and the way it behaves when it is intermittently heated, as it is important for you to select the plant and design the system that will best suit the building and its use. It is assumed that you have some knowledge of building services.

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