Population of the world

To get some idea of how large this number is, suppose the entire population of the world were assigned to counting the atoms in 4.003 g of helium. If each person counted one atom per second and worked a 48-hour week, the task would take more than 10 million years. 

We are in a changing world. It has taken two thousand years for the population of the world to grow from 250 million to the near 6 billion people today. But in the next fifty years world population is projected to grow to about 10 billion people.1 How will future world needs be met ... 

With the twentieth century came enormous progress in the development of the chemical industry. Chemistry transformed agriculture. Artificial fertilizers provided the means of feeding the enormous, growing population of the world. Chemistry transformed communications and transportation. It provided advanced materials, like silicon for computers and glass for optical fibers it developed more efficient and renewable... 

For theoretical chemistry to succeed it must develop the power to elucidate the behaviour of chemical substances to the satisfaction of experimental chemists, known to operate at many different levels. Understanding is not promoted by the generation of numbers, however accurate or numerous, without a simple picture that tells the story. It is inevitable that the chain of reasoning must reduce the problem of understanding the behaviour of substances, to the understanding of molecules, atoms, electrons, and eventually the aether. Again, this ladder of understanding should not be obscured by complicated mathematical relationships that cannot be projected into a simple picture. Small wonder that the planetary model of the atom, inspired by Kepler, and discredited almost a hundred years ago, is still the preferred icon to represent nuclear installations and activity in the commercial world. Theoretical chemistry should also communicate with the predominantly nonscientist population of the world, but in order to tell a story it is first of all necessary to know the story. 

The enzyme lactase catalyzes the hydrolysis of lactose in the lumen of the gut. Generally, intestinal lactase activity occurs at a maximal level from birth through early childhood. Then activity declines to a residual level of 5 10% by the age of. 3 or later in most populations of the world. In persons of European descent, lactase activity can remain at a high level throughout adulthood. Low levels of lactase... 

Just how small is a typical atom To get some idea of its size, consider the population of the world. In the year 2000, the world population was approximately 6 000 000 000 (six billion) people. By comparison, a typical solid copper penny contains almost five billion times as many atoms of copper ... 

RDA values relate primarily to populations of developed countries and are intended to meet the needs of virtually all healthy individuals. Thus, the allowances are far higher than demanded by physiological needs, and for many populations of the world, the RDA estimates may be inappropriately high. If the intake of a given nutrient is below the RDA value, nutritional inadequacy does not necessarily result. However, if a particular deficiency is accompanied by biochemical and clinical abnormalities, then corrective action is needed. 

Hayes (5) has also reviewed the contribution of pesticides to the control of human diseases spread by arthropods and other vectors. Outbreaks of malaria, louse-borne typhus, plague, and urban yellow fever, four of the most important epidemic diseases of history, have been controlled by use of the organochlorine insecticides, especially DDT. In fact, the single most significant benefit from pesticides has been the protection from malaria. Today malaria eradication is an accomplished fact for 619 million people who live in areas once malarious. Where eradication has been achieved it has stood the test of time. An additional 334 million people live in areas where transmission of the parasite is no longer a major problem. Thus, about 1 billion people, or approximately one-fourth of the population of the world, no longer live under the threat of malaria. 

Levels of radon in water vary widely, normally being much greater in deep water supplies than in surface water. As a general rule levels in surface water will be similar to Ra levels — i.e. about 10 Bq m. For groimd water extracted from deep wells drilled in granitic areas much higher levels are found. For example, levels of up to 77 MBq m have been found in Finland and of around 20 MBq m in the US. It has been estimated that from 1% to 10% of the population of the world drink water derived from deep wells with a radon concentration in excess of some 100 kBq m while the remainder drink water from surface sources with an average radon concentration of below about 1 kBq m. ... 

Another source of unused lignocellulose is straw derived from rice, wheat, and other cereals. For example, one third of the population of the world lives on rice. The great bulk of the rice straw, however, is unused. A small amount is pulped (Egypt). 

Bacteria learn resistance in an inexorable exponential growth curve, and using mathematical modeling researchers had predicted with uncanny accuracy, almost to the month, when vancomycin-resistant staph would appear. It will now proceed into the general population of the world at that same exponential rate. Though scientists hope to stop it, there is in actuality little they can do. Stuart Levy observes that "some analysts warn of present-day scenarios in which infectious antibiotic-resistant bacteria devastate whole human populations."... 

Let us first evaluate the genetic effect of the carbon-14 from bomb tests on the assumption that the population of the world will remain constant. 

Radioactivity, natural. The property of radioactivity exhibited hy more than fifty naturally occurring radionuclides e.g., uranium 238 and radium emit gamma rays and alpha and beta particles. The entire population of the world is exposed to natural radioactivity, and always has been. 

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