Explore Related Concepts

bone mass percentage chart

Best Results From Wikipedia Yahoo Answers Encyclopedia Youtube

From Wikipedia

Pie chart

A pie chart (or a circle graph) is a circularchart divided into sectors, illustrating proportion. In a pie chart, the arc length of each sector (and consequently its central angle and area), is proportional to the quantity it represents. When angles are measured with 1 turn as unit then a number of percent is identified with the same number of centiturns. Together, the sectors create a full disk. It is named for its resemblance to a pie which has been sliced. The earliest known pie chart is generally credited to William Playfair's Statistical Breviary of 1801.

The pie chart is perhaps the most ubiquitous statistical chart in the business world and the mass media. However, it has been criticized, and some recommend avoiding it, pointing out in particular that it is difficult to compare different sections of a given pie chart, or to compare data across different pie charts. Pie charts can be an effective way of displaying information in some cases, in particular if the intent is to compare the size of a slice with the whole pie, rather than comparing the slices among them. Pie charts work particularly well when the slices represent 25 to 50% of the data, but in general, other plots such as the bar chart or the dot plot, or non-graphical methods such as tables, may be more adapted for representing certain information.It also shows the frequency within certain groups of information.


The following example chart is based on preliminary results of the election for the European Parliament in 2004. The table lists the number of seats allocated to each party group, along with the derived percentage of the total that they each make up. The values in the last column, the derived central angle of each sector, is found by multiplying the percentage by 360°.

*Because of rounding, these totals do not add up to 100 and 360.

The size of each central angle is proportional to the size of the corresponding quantity, here the number of seats. Since the sum of the central angles has to be 360°, the central angle for a quantity that is a fraction Q of the total is 360Q degrees. In the example, the central angle for the largest group (European People's Party (EPP)) is 135.7° because 0.377 times 360, rounded to one decimal place(s), equals 135.7.

Use, effectiveness and visual perception

Pie charts are common in business and journalism, perhaps because they are perceived as being less "geeky" than other types of graph. However statisticians generally regard pie charts as a poor method of displaying information, and they are uncommon in scientific literature. One reason is that it is more difficult for comparisons to be made between the size of items in a chart when area is used instead of length and when different items are shown as different shapes. Stevens' power law states that visual area is perceived with a power of 0.7, compared to a power of 1.0 for length. This suggests that length is a better scale to use, since perceived differences would be linearly related to actual differences.

Further, in research performed at AT&T Bell Laboratories, it was shown that comparison by angle was less accurate than comparison by length. This can be illustrated with the diagram to the right, showing three pie charts, and, below each of them, the corresponding bar chart representing the same data. Most subjects have difficulty ordering the slices in the pie chart by size; when the bar chart is used the comparison is much easier.. Similarly, comparisons between data sets are easier using the bar chart. However, if the goal is to compare a given category (a slice of the pie) with the total (the whole pie) in a single chart and the multiple is close to 25 or 50 percent, then a pie chart can often be more effective than a bar graph.

Variants and similar charts

Polar area diagram

The polar area diagram is similar to a usual pie chart, except sectors are equal angles and differ rather in how far each sector extends from the center of the circle. The polar area diagram is used to plot cyclic phenomena (e.g., count of deaths by month). For example, if the count of deaths in each month for a year are to be plotted then there will be 12 sectors (one per month) all with the same angle of 30 degrees each. The radius of each sector would be proportional to the square root of the death count for the month, so the area of a sector represents the number of deaths in a month. If the death count in each month is subdivided by cause of death, it is possible to make multiple comparisons on one diagram, as is clearly seen in the form of polar area diagram famously developed by Florence Nightingale.

The first known use of polar area diagrams was by André-Michel Guerry, which he called courbes circulaires, in an 1829 paper showing seasonal and daily variation in wind direction over the year and births and deaths by hour of the day. Léon Lalanne later used a polar diagram to show the frequency of wind directions around compass points in 1843. The wind rose is still used by meteorologists. Nightingale published her rose diagram in 1858. The name "coxcomb" is sometimes used erroneously. This was the name Nightingale used to refer to a book containing the diagrams rather than the diagrams themselves. It has been suggested that most of Nightingale's early reputation was built on her ability to give clear and concise presentations of data.

Spie chart

A useful variant of the polar area chart is the spie chart designed by Feitelson . This superimposes a normal pie chart with a modified polar area chart to permit the comparison of a set of data at two different states. For the first state, for example time 1, a normal pie chart is drawn. For the second state, the angles of the slices are the same as in the original pie chart, and the radii vary according to the change in the value of each variable. In addition to comparing a partition at two times (e.g. this year's budget distribution with last year's budget distribution), this is useful for visualizing hazards for population groups (e.g. the distribution of age and gener groups among road casualties compared with these groups's sizes in the general population). The R Graph Gallery provides an example.

Multi-level pie chart

Multi-level pie chart, also known as a radial tree c

Active rock

Active rock is a radio format used by many commercial radio stations across Canada and the United States. Active rock plays current rock artists with a mix of classic rock songs.

Format background

An active rock station may include songs by "classic" artists in its playlist, whereas a modern rock station would not. Conversely, unlike classic rock stations, an active rock station also plays music by popular current and new rock artists.

Similar to active rock stations, mainstream rock stations play current rock music, but concentrate more on classic rock than active rock stations do.

A pioneering station of this format in the late 1980s was WIYY "98Rock" in Baltimore, Maryland. Other early adopters of this format by the beginning of the 1990s include stations KISS "99.5 KISS Rocks" in San Antonio, TX, WAAF in Boston, Massachusetts, WXTB "98Rock" in Tampa, Florida, WGIR (FM) "Rock 101" in Manchester, New Hampshire and KEGL, "97.1 The Eagle ", in Dallas/Fort Worth, Texas. Satellite radio channels include Sirius XM Radio's Octane, and the gold-basedBone Yard channel, also on Sirius XM Radio. Former counterparts prior to the November 12, 2008 Sirius/XM channel merger were XM'sSquizz and Sirius'sBuzzSaw. Australian radio network Triple M Network also uses this format. A later Internet radio station, [http://frogboxradio.net Frogbox Radio], also began playing an Active rock format.

Active rock stations in Canada also include CFBR-FM in Edmonton, CHTZ-FM in St. Catharines and CJKR-FM in Winnipeg.

Active Rock Airplay chart

Active Rock Airplay Chart is a chart that compiles the current hits on Active Rock radio stations and is used as a component for the Billboard Mainstream Rock chart. This chart is exclusive to R&R, with forty positions on this chart and it is solely based on radio airplay. 62 Active Rock radio stations are electronically monitored 24 hours a day, seven days a week by Nielsen Broadcast Data Systems. Songs are ranked by a calculation of the total number of spins per week with its "audience impression", which is based upon exact times of airplay and each station's Arbitron listener data.

Songs receiving the greatest growth will receive a "bullet", although there are tracks that will also get bullets if the loss in detections doesn't exceed the percentage of downtime from a monitored station. "Airpower" awards are issued to songs that appear on the top 20 of both the airplay and audience chart for the first time, while the "greatest gainer" award is given to song with the largest increase in detections. A song with six or more spins in its first week is awarded an "airplay add". If a song is tied for the most spins in the same week, the one with the biggest increase that previous week will rank higher, but if both songs show the same amount of spins regardless of detection the song that is being played at more stations is ranked higher. Songs that fall below the top 20 and have been on the chart after 20 weeks are removed and go to recurrent status.

Body shape

Human body shape is a complex phenomenon with sophisticated detail and function. The general shape or figure of a person is defined mainly by skeletal structure, muscles and fat. Skeletal structure grows and changes only up to the point at which a human reaches adulthood and remains essentially the same for rest of his or her life.

During puberty, differentiation of the male and female body occurs for the purposes of reproduction. In adult humans, muscle mass may change due to exercise, and fat distribution may change due to hormone fluctuations. Inherited genes play a large part in the development of body shape.

Body shape has effects on body posture and gait, and has a major role in physical attraction. This is because a body's shape implies an individual's hormone levels during puberty, which implies fertility, and it also indicates current levels of sex hormones. A pleasing shape also implies good health and fitness of the body. The art of figure drawing defines body proportions that are considered ideal.

Skeletal structure

Skeletal structure frames the overall shape of the body and does not alter much over a lifetime. Males are generally taller, but body shape may be analyzed after normalizing with respect to height.

Broad shoulders and expanded chest (in males):
Widening of the shoulders occurs as part of the male pubertal process. Expansion of the ribcage is caused by the effects of testosterone during puberty. Hence males generally have broad shoulders and expanded chests, allowing them to inhale more air to supply their muscles with oxygen.
Wide hips (in females):
Widening of the hip bones occurs as part of the female pubertal process, and estrogen (the predominant sex hormone in females) causes a widening of the pelvis as a part of sexual differentiation. Hence females generally have wider hips, permitting childbirth. Because the female pelvis is flatter, more rounded and proportionally larger, the head of the fetus may pass during childbirth. The sacrum in females is shorter and wider, and also directed more toward the rear (see image). This affects their walking style, resulting in hip sway; also, females generally stand with hips relaxed to one side.

After puberty, female hips are generally wider than female shoulders; males exhibit the opposite configuration. But not everyone follows this stereotypical pattern of secondary sex characteristics. Both male and female hormones are present in the human body, and though only one of them is predominant in an adult, the other hormone has effects on body's shape to some extent.

Facial features

Due to the action of testosterone, males develop these facial-bone features during puberty:

  • A more prominent brow bone.
  • A heavier jaw.
  • More prominent chin.
  • Larger nose bone.

Because females have around 20 times less testosterone, these features do not develop to the same extent. Hence female faces are generally more similar to those of pre-pubertal children.

Fat distribution, muscles and tissues

Body shape is affected by body fat distribution, which is correlated to current levels of sex hormones. Muscles and fat distribution may change from time to time, unlike bone structure, depending on food habits, exercises and hormone levels.

Fat distribution

Estrogen causes fat to be stored in the buttocks, thighs, and hips in women. When women reach menopause and the oestrogen produced by ovaries declines, fat migrates from their buttocks, hips and thighs to their waists; later fat is stored in the belly. Thus females generally have relatively narrow waists and large buttocks, and this along with wide hips make for a wider hip section and a lower waist-hip ratio compared to men.

Estrogen increases fat storage in the body, which results in more fat stored in the female body. Body fat percentage recommendations are higher for females, as this may serve as an energy reserve for pregnancy. Males have less subcutaneous fat in their faces due to the effects of testosterone; testosterone also reduces fat by aiding fat metabolism. Males generally deposit fat around waists and nonlinearcurrent–voltage characteristic. The name is a portmanteau of variable resistor. Varistors are often used to protectcircuits against excessive transient voltages by incorporating them into the circuit in such a way that, when triggered, they will shunt the current created by the high voltage away from the sensitive components. A varistor is also known as Voltage Dependent Resistor or VDR. A varistor’s function is to conduct significantly increased current when voltage is excessive.

Note: only non-ohmic variable resistors are usually called varistors. Other, ohmic types of variable resistor include thepotentiometer and the rheostat.

Metal oxide varistor

The most common type of varistor is the Metal Oxide Varistor (MOV). This contains a ceramic mass of zinc oxide grains, in a matrix of other metal oxides (such as small amounts of bismuth, cobalt, manganese) sandwiched between two metal plates (the electrodes). The boundary between each grain and its neighbour forms a diode junction, which allows current to flow in only one direction. The mass of randomly oriented grains is electrically equivalent to a network of back-to-back diode pairs, each pair in parallel with many other pairs. When a small or moderate voltage is applied across the electrodes, only a tiny current flows, caused by reverse leakage through the diode junctions. When a large voltage is applied, the diode junction breaks down due to a combination of thermionic emission and electron tunneling, and a large current flows. The result of this behavior is a highly nonlinear current-voltage characteristic, in which the MOV has a high resistance at low voltages and a low resistance at high voltages.

Follow-through current as a result of a lightning strike may generate excessive current that permanently damages a varistor. In general, the primary case of varistor breakdown is localized heating caused as an effect of thermal runaway. This is due to a lack of conformality in individual grain-boundary junctions, which leads to the failure of dominant current paths under thermal stress.

Varistors can absorb part of a surge. How much effect this has on risk to connected equipment depends on the equipment and details of the selected varistor. Varistors do not absorb a significant percentage of a lightning strike, as energy that must be conducted elsewhere is many orders of magnitude greater than what is absorbed by the small device.

A varistor remains non-conductive as a shunt mode device during normal operation when voltage remains well below its "clamping voltage". If a transient pulse (often measured in joules) is too high, the device may melt, burn, vaporize, or otherwise be damaged or destroyed. This (catastrophic) failure occurs when "Absolute Maximum Ratings" in manufacturer's datasheet are significantly exceeded. Varistor degradation is defined by manufacturer's life expectancy charts using curves that relate current, time, and number of transient pulses. A varistor fully degrades typically when its "clamping voltage" has changed by 10%. A fully degraded varistor remains functional (no catastrophic failure) and is not visibly damaged.

Ballpark number for varistor life expectancy is its energy rating. As MOV joules increase, the number of transient pulses increases and the "clamping voltage" during each transient decreases. The purpose of this shunt mode device is to divert a transient so that pulse energy will be dissipated elsewhere. Some energy is also absorbed by the varistor because a varistor is not a perfect conductor. Less energy is absorbed by a varistor, the varistor is more conductive, and its life expectancy increases exponentially as varistor energy rating is increased. Catastrophic failure can be avoided by significantly increasing varistor energy ratings either by using a varistor of higher joules or by connecting more of these shunt mode devices in parallel.

Important parameters are the varistor's energy rating in joules, operating voltage, response time, maximum current, and breakdown (clamping) voltage. Energy rating is often defined using standardized transients such as 8/20 microseconds or 10/1000 microseconds, where 8 microseconds is the transient's front time and 20 microseconds is the time to half value.

To protect communications lines (such as telephone lines) transient suppression devices such as 3 mil carbon blocks (IEEE C62.32), ultra-low capacitance varistors or avalanche diodes are used. For higher frequencies such as radio communication equipment, a gas discharge tube (GDT) may be utilized.

A typical surge protectorpower strip is built using MOVs. A cheapest kind may use just one varistor, from hot (live, active) to neutral. A better protector would contain at least three varistors; one across each of the three pairs of conductors (hot-neutral, hot-ground, neutral-ground). A power strip protector in the United States should have a UL1449 3rd edition approval so that catastrophic MOV failure would not create a fire hazard.


While a MOV is designed to conduct significant power for very short durations (≈ 8/20 microseconds), such as caused by lightning strikes, it typically does not have the capacity to conduct sustained energy. Under normal utility voltage conditions, this is not a problem. However, certain types of faults on the utility power grid can result in sustained over-voltage conditions. Examples include a loss of a neutral conductor or shorted lines on the high voltage system. Application of sustained over-voltage to a MOV can cause high dissipation, potentially resulting in the MOV device catching fire. The National Fire Protection Association (NFPA) has documented many cases of catastrophic fires that have been caused by MOV devices in surge suppressors, and has issued bulletins on the issue.

A seri

From Encyclopedia

Actinium (revised)

Note: This article, originally published in 1998, was updated in 2006 for the eBook edition. Actinium is the third element in Row 7 of the periodic table, a chart that shows how the chemical elements are related to each other. Some chemists place it in Group 3 (IIIB), with scandium and yttrium. Other chemists call it the first member of the actinides. The actinides are the 14 elements that make up Row 7 of the periodic table. They have atomic numbers from 89 to 103 and are all radioactive. A radioactive atom is unstable and tends to throw off particles and emit energy in order to become stable. Either way of classifying actinium is acceptable to most chemists. Actinium has chemical properties like those of lanthanum (number 57), the element just above it in the periodic table. Actinium is also similar to radium, the element just before it (number 88) in Row 7. Naturally occurring actinium is very rare in the Earth's crust. It can be made in the lab by firing neutrons at radium, but it has very few important uses. SYMBOL Ac ATOMIC NUMBER 89 ATOMIC MASS 227.0278 FAMILY Group 3 (IIIB) Transition metal PRONUNCIATION ack-TIN-ee-um Four new elements, all radioactive, were discovered between 1898 and 1900. A radioactive element is one that gives off radiation in the form of energy or particles and may change into a different element. The first two of these elements—polonium and radium—were discovered by Marie Curie (1867-1934) and Pierre Curie (1859-1906). The third, actinium, was discovered in 1899 by a close friend of the Curies, French chemist André Debierne (1874-1949). Debierne suggested the name actinium for the new element. The name comes from the Greek words aktis or aktinos, meaning "beam" or "ray." The fourth element discovered in this series was radon, a gas given off during the radioactive decay of some heavier elements. It was found in 1900 by German chemist Friedrich Ernst Dorn (1848-1916). Actinium was discovered a second time in 1902. German chemist Friedrich 0. Giesel (1852-1927) had not heard of Debierne's earlier discovery. Giesel suggested the name emanium, from the word emanation, which means "to give off rays." Debierne's name was adopted, however, because he discovered actinium first. Only limited information is available about actinium. It is known to be a silver metal with a melting point of 1,050°C (1,920°F) and a boiling point estimated to be about 3,200°C (5,800°F). The element has properties similar to those of lanthanum. Generally speaking, elements in the same column in the periodic table have similar properties. Few compounds of actinium have been produced. Neither the element nor its compounds have any important uses. Actinium is found in uranium ores. An ore is a mineral mined for the elements it contains. It is produced by the radioactive decay, or breakdown, of uranium and other unstable elements. Actinium can also be artificially produced. When radium is bombarded with neutrons, some of the neutrons become part of the nucleus. This increases the atomic weight and the instability of the radium atom. The unstable radium decays, gives off radiation, and changes to actinium. Actinium metal of 98 percent purity—used for research purposes—can be made by this process. About a dozen isotopes of actinium are known. All are radioactive. The two that occur in nature are actinium-227 and actinium-228. Isotopes are two or more forms of an element. Isotopes differ from each other according to their mass number. The number written to the right of the element's name is the mass number. The mass number represents the number of protons plus neutrons in the nucleus of an atom of the element. The number of protons determines the element, but the number of neutrons in the atom of any one element can vary. Each variation is an isotope. A radioactive isotope is one that breaks apart and gives off some form of radiation. The half lives of actinium-227 and actinium-228 are 21.77 years and 6.13 hours, respectively. The half life of a radioactive element is the time it takes for half of a sample of the element to break down. For example, suppose 1.0 gram of actinium-227 is formed by the breakdown of another element. After 21.77 years, only 0.5 gram of actinium-227 would remain. This is known as the half life. Actinium is rarely, if ever, extracted from natural sources. There are no practical commercial uses of actinium. Actinium of 98 percent purity is prepared for research studies. The few compounds of actinium that are known are used solely for research purposes. Like all radioactive materials, actinium is a health hazard. Like all radioactive materials, actinium is a health hazard. If taken into the body, it tends to be deposited in the bones, where the energy it emits damages or destroys cells. Radiation is known to cause bone cancer and other disorders.


Along the extreme right-hand column of the periodic table of elements is a group known as the noble gases: helium, neon, argon, krypton, xenon, and radon. Also known as the rare gases, they once were called inert gases, because scientists believed them incapable of reacting with other elements. Rare though they are, these gases are a part of everyday life, as evidenced by the helium in balloons, the neon in signs—and the harmful radon in some American homes. The periodic table of elements is ordered by the number of protons in the nucleus of an atom for a given element (the atomic number), yet the chart is also arranged in such a way that elements with similar characteristics are grouped together. Such is the case with Group 8, which is sometimes called Group 18, a collection of non-metals known as the noble gases. The six noble gases are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and radon (Rn). Their atomic numbers are, respectively, 2, 10, 18, 36, 54, and 86. Several characteristics, aside from their placement on the periodic table, define the noble gases. Obviously, all are gases, meaning that they only form liquids or solids at extremely low temperatures—temperatures that, on Earth at least, are usually only achieved in a laboratory. They are colorless, odorless, and tasteless, as well as monatomic—meaning that they exist as individual atoms, rather than in molecules. (By contrast, atoms of oxygen—another gas, though not among this group—usually combine to form a molecule, O2.) There is a reason why noble gas atoms tend not to combine: one of the defining characteristics of the noble gas "family" is their lack of chemical reactivity. Rather than reacting to, or bonding with, other elements, the noble gases tend to remain apart—hence the name "noble," implying someone or something that is set apart from the crowd, as it were. Due to their apparent lack of reactivity, the noble gases—also known as the rare gases—were once known as the inert gases. Indeed, helium, neon, and argon have not been found to combine with other elements to form compounds. However, in 1962 English chemist Neil Bartlett (1932-) succeeded in preparing a compound of xenon with platinum and fluorine (XePtF6), thus overturning the idea that the noble gases were entirely "inert." Since that time, numerous compounds of xenon with other elements, most notably oxygen and fluorine, have been developed. Fluorine has also been used to form simple compounds with krypton and radon. Nonetheless, low reactivity—instead of no reactivity, as had formerly been thought—characterizes the rare gases. One of the factors governing the reactivity of an element is its electron configuration, and the electrons of the noble gases are arranged in such a way as to discourage bonding with other elements. Helium is an unusual element in many respects—not least because it is the only element to have first been identified in the Solar System before it was discovered on Earth. This is significant, because the elements on Earth are the same as those found in space: thus, it is more than just an attempt at sounding poetic when scientists say that humans, as well as the world around them, are made from "the stuff of stars." In 1868, a French astronomer named Pierre Janssen (1824-1907) was in India to observe a total solar eclipse. To aid him in his observations, he used a spectroscope, an instrument for analyzing the spectrum of light emitted by an object. What Janssen's spectroscope showed was surprising: a yellow line in the spectrum, never seen before, which seemed to indicate the presence of a previously undiscovered element. Janssen called it "helium" after the Greek god Helios, or Apollo, whom the ancients associated with the Sun. Janssen shared his findings with English astronomer Sir Joseph Lockyer (1836-1920), who had a worldwide reputation for his work in analyzing light waves. Lockyer, too, believed that what Janssen had seen was a new element, and a few months later, he observed the same unusual spectral lines. At that time, the spectroscope was still a new invention, and many members of the worldwide scientific community doubted its usefulness, and therefore, in spite of Lockyer's reputation, they questioned the existence of this "new" element. Yet during their lifetimes, Janssen and Lockyer were proven correct. They had to wait a quarter century, however. In 1893, English chemist Sir William Ramsay (1852-1916) became intrigued by the presence of a mysterious gas bubble left over when nitrogen from the atmosphere was combined with oxygen. This was a phenomenon that had also been noted by English physicist Henry Cavendish (1731-1810) more than a century before, but Cavendish could offer no explanation. Ramsay, on the other hand, had the benefit of observations made by English physicist John William Strutt, Lord Rayleigh (1842-1919). Up to that time, scientists believed that air consisted only of oxygen, carbon dioxide, and water vapor. However, Rayleigh had noticed that when nitrogen was extracted from air after a process of removing those other components, it had a slightly higher density than nitrogen prepared from a chemical reaction. In light of his own observations, Ramsay concluded that whereas nitrogen obtained from chemical reactions was pure, the nitrogen extracted from air contained trace amounts of an unknown gas. Ramsay was wrong in only one respect: hidden with the nitrogen was not one gas, but five. In order to isolate these gases, Ramsay and Rayleigh subjected air to a combination of high pressure and low temperature, allowing the various gases to boil off at different temperatures. One of the gases was helium—the first confirmation that the element existed on Earth—but the other four gases were previously unknown. The Greek roots of the names given to the four gases reflected scientists' wonder at discovering these hard-to-find elements: neos (new), argos (in active), kryptos (hidden), and xenon (stranger). Inspired by the studies of Polish-French physicist and chemist Marie Curie (1867-1934) regarding the element radium and the phenomenon of radioactivity (she discovered the element, and coined the latter term), German physicist Friedrich Dorn (1848-1916) became fascinated with radium. Studying the element, he discovered that it emitted a radioactive gas, which he dubbed "radium emanation." Eventually, however, he realized that what was being produced was a new element. This was the first clear proof that one element could become another through the process of radioactive decay. Ramsay, who along with Rayleigh had received the Nobel Prize in 1904 for his work on the noble gases, was able to map the new element's spectral lines and determine its density and atomic mass. A few years later, in 1918, another scientist named C. Schmidt gave it the name "radon." Due to its behavior and the configuration of its electrons, chemists classified radon among what they continued to call the "inert gases" for another half-century—until Bartlett's preparation of xenon compounds in 1962. Though the rare gases are found in minerals and meteorites on Earth, their greatest presence is in the planet's atmosphere. It is believed that they were released into the air long ago as a by-product of decay on the part of radioactive materials in the Earth's crust. Within the atmosphere, argon is the most "abundant"—in comparative terms, given the fact that the "rare gases" are, by definition, rare. Nitrogen makes up about 78% of Earth's atmosphere and oxygen 21%, meaning that these two elements constitute fully 99% of the air above the Earth. Argon ranks a distant third, with 0.93%. The remaining 0.07% is made up on water vapor, carbon dioxide, ozone (O3), and traces of the noble gases. These are present in such small quantities that the figures for them are not typically presented as percentages, but rather in terms of parts per million (ppm). The concentrations of neon, helium, krypton, and xenon in the atmosphere are 18, 5, 1, and 0.09 ppm respectively. Radon in the atmosphere is virtually negligible, which is a fortunate thing, in light of its

From Yahoo Answers

Question:I am 33, 5 foot 6, very active (swim, walk a lot, have started yoga and belly dancing, and do sit-ups, 25 a day, and push ups about 15 a day). I have a lot of muscle in my arms and legs. I have a little bit of a baby condo left from having my third child, but other then that my stomach is relatively flat. My BP is usually around 110/60. But here is the thing, I way 223 lbs. When I have people geuss my weight people usually say about 150, I know some of that is trying to be polite but some seem genuinely suprised when I say what I weigh. According to the BMI I am morbidly obese, but I don't feel it. I told my mother and a co-worker that I want to lose 70 lbs they said that I would look like a skeleton. My doctor says weightloss would be good, but he also says that I am in perfect health, so what do you folks think???? Go by weight or go by how you look, act and feel?????

Answers:BMI is only an estimate of your weight distribution. It does not really take into account or differentiate muscle/fat ratios or bone structure. When I was in the army the soldiers who worked out with heavy weights and therefore had higher than usual muscle mass (which is denser than fat) always exceeded the charts and had to have more specialized measurements done. The most accurate way to determine your muscle/fat ratio is to have a physician weigh you on dry land and also submersed in a pool. Since fat is less dense than muscle the difference in weight between the dry weigh-in and the submerged weigh-in gives a more accurate measure of fat percentage in your body weight. If you are truly concerned then you should consult with a physician who will use a more precise evaluation than just looking at a chart. Diet and activity levels are as important in determining over all health as is body fat levels.

Question:I have just purchased the MaxView Analyser Scale, Model: 9124SS3R. It gives me the following readings regarding my body composition: Total weight: 136lbs. Body fat percentage: 20.9% Muscle mass: 39.7% body water: 50.9% For some reason my body fat and muscle mass don't add up to my total weight. I can't seem to figure out why not, or even if they are supposed to. At the moment there is a significant amount of my body weight left unaccounted for. Any help would be appreciated. Re: bone organs etc. Yes this is what I was thinking, but how much total weight should be attributed to these? Also re: the calculation of body fat + body water + muscle mass = total weight, based on the stats given these add up to more than my total weight. Does any one know why a large amount of total weight would be unaccounted for?

Answers:You're made up of more than muscle and fat, otherwise it would be possible to get your weight near 0 lbs.

Question:I have this weight watchers scale(it's super light and slim if anyone knows the specific one I am talking about) this scale that reads body fat weight, percentage, bmi, body water and bone mass. I went on it today. does this sound healthy? most of these are in KG unit. ((the decimal points might be in the wrong place because it's really hard to read them when your on the scale)) Height: 5ft 6inches 55.5 KG ((122 pounds)) 5.0 body fat weight ((kg i'm guessing)) 11.0 body fat percentage 20.0 BMI 19.7 BODY WATER( percentage) 58.4 bone mass ((again the decimals may be in the wrong place. cuz they are really tiny and small to read when your standing up on scale))((Makes more sense if this one was PERCENTAGE TOO)) and the last number was 6.6 but was not sure what that was for or whatever.

Answers:You sound healthy to me. 5'6" and 122 lbs is a good weight. A 20 BMI is also good.

Question:I am just starting a new regimen of watching calorie intake, excercising 3 times a week (treadmill at 3 mph 20 min, hand weights, resistance chords) What else can I do? Should I be concerned with the % Body water? Research on the web says I should have more like 50-60% body water? Thanks for the advice! Here are my stats: 33yrs old current weight 305.8lbs 58.6% Body Fat Bone Mass = 4.6 lbs Body Water = 31.6% Muscle Mass = 34.8% BMI = 41

Answers:give yourself time to adjust. you wont lose weight right away. sometimes those devices that read body water percentage and stuff like that arent very reliable. i wouldnt read to much into it.

From Youtube

Beurer BG55 Glass diagnostic scale :High quality design Everything at a glance With interpretation and trend display Extra large display for simultaneous display of the values determined Interpretation of body weight, body fat, body water and muscle percentage Basic calorie rate and active metabolic rate Trend display (reading is compared with the average of the last 5 readings) Graduation: 0.1% for body fat, body water and muscle percentage, 100g for body weight, ideal weight and bone mass 5 activity levels 10 memories each with 5 memory spaces for readings 28 mm digit height Switchover from kg/lb/st Standing surface 32 x 32 cm 150 kg capacity Incl. batteries 5 year warranty