Per Cent Mille
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Per Cent Mille
A per cent mille or pcm is one one-thousandth of a percent. It can be thought of as a "milli-percent". It is commonly used in epidemiology, and in nuclear reactor engineering as a unit of reactivity. Epidemiology Statistics of Crime statistics, crime rates, Mortality rate, mortality and Prevalence, disease prevalence in a population are often given in Nuclear Reactivity In nuclear reactor engineering, a per cent mille is equal to one-thousandth of a percent of the Nuclear reactor physics#criticality, reactivity, denoted by Greek lowercase letter rho. Reactivity is a dimensionless unit representing a departure from Criticality (status), criticality, calculated by: :\rho=(k_-1)/k_ where keff denotes the effective multiplication factor for the reaction. Therefore, one pcm is equal to: :1~\text = \rho \cdot 10^5 This unit is commonly used in the operation of light-water reactor sites because reactivity values tend to be small, so measuring in pcm allows reactivity to be expressed u ...
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Epidemiology
Epidemiology is the study and analysis of the distribution (who, when, and where), patterns and risk factor, determinants of health and disease conditions in a defined population. It is a cornerstone of public health, and shapes policy decisions and evidence-based practice by identifying risk factors for disease and targets for preventive healthcare. Epidemiologists help with study design, collection, and statistical analysis of data, amend interpretation and dissemination of results (including peer review and occasional systematic review). Epidemiology has helped develop methodology used in clinical research, public health studies, and, to a lesser extent, basic research in the biological sciences. Major areas of epidemiological study include disease causation, transmission (medicine), transmission, outbreak investigation, disease surveillance, environmental epidemiology, forensic epidemiology, occupational epidemiology, screening (medicine), screening, biomonitoring, and compa ...
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Percentage
In mathematics, a percentage (from la, per centum, "by a hundred") is a number or ratio expressed as a fraction (mathematics), fraction of 100. It is often Denotation, denoted using the percent sign, "%", although the abbreviations "pct.", "pct" and sometimes "pc" are also used. A percentage is a Dimensionless quantity, dimensionless number (pure number); it has no unit of measurement. Examples For example, 45% (read as "forty-five per cent") is equal to the fraction , the ratio 45:55 (or 45:100 when comparing to the total rather than the other portion), or 0.45. Percentages are often used to express a proportionate part of a total. (Similarly, one can also express a number as a fraction of 1,000, using the term "per mille" or the symbol "".) Example 1 If 50% of the total number of students in the class are male, that means that 50 out of every 100 students are male. If there are 500 students, then 250 of them are male. Example 2 An increase of $0.15 on a price of $2.50 ...
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Per-unit System
In the power systems, power systems analysis field of electrical engineering, a per-unit system is the expression of system quantities as fractions of a defined base unit quantity. Calculations are simplified because quantities expressed as per-unit do not change when they are referred from one side of a transformer to the other. This can be a pronounced advantage in power system analysis where large numbers of transformers may be encountered. Moreover, similar types of apparatus will have the impedances lying within a narrow numerical range when expressed as a per-unit fraction of the equipment rating, even if the unit size varies widely. Conversion of per-unit quantities to volts, ohms, or amperes requires a knowledge of the base that the per-unit quantities were referenced to. The per-unit system is used in Power flow study, power flow, short circuit evaluation, motor starting methods, motor starting studies etc. The main idea of a per unit system is to absorb large differences i ...
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Dollar (reactivity)
A dollar is a unit of reactivity for a nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu ..., calibrated to the interval between the conditions of delayed criticality and prompt criticality In nuclear engineering Nuclear engineering is the branch of engineering Engineering is the use of scientific principles to design and build machines, structures, and other items, including bridges, tunnels, roads, vehicles, and building .... Zero dollars is defined to be the threshold of slow criticality, which means a steady reaction rate. One dollar is defined to be the threshold of prompt criticality, which means a nuclear excursion or explosion. A cent is of a dollar. Meaning and use Each nuclear fission Nuclear fission is a nuclear reaction, reaction in ...
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InHour
InHour is a unit Unit may refer to: Arts and entertainment * UNIT, a fictional military organization in the science fiction television series ''Doctor Who'' * Unit of action, a discrete piece of action (or beat) in a theatrical presentation Music * Unit (album), ... of reactivity of a nuclear reactor A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nu .... It stands for the inverse Inverse or invert may refer to: Science and mathematics * Inverse (logic), a type of conditional sentence which is an immediate inference made from another conditional sentence * Additive inverse (negation), the inverse of a number that, when ad ... of an hour An hour (metric symbol, symbol: h; also abbreviated hr) is a unit of measurement, unit of time conventionally reckoned as of a day and scien ...
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Parts-per Notation
In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantity, dimensionless quantities, e.g. mole fraction or mass fraction (chemistry), mass fraction. Since these fraction (mathematics), fractions are quantity-per-quantity measures, they are pure numbers with no associated units of measurement. Commonly used are parts-per-million (ppm, ), parts-per-billion (ppb, ), parts-per-trillion (ppt, ) and parts-per-quadrillion (ppq, ). This notation is not part of the International System of Units (SI) system and its meaning is ambiguous. Overview Parts-per notation is often used describing dilute solutions in chemistry, for instance, the relative abundance of dissolved minerals or pollutants in water. The quantity "1 ppm" can be used for a mass fraction if a water-borne pollutant is present at one-millionth of a gram per gram of sample solution. When working with aqueous solutions, it is common to assume ...
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Permyriad
A basis point (often abbreviated as bp, often pronounced as "bip" or "beep") is one hundredth of 1 percentage point. The related term ''#Permyriad, permyriad'' means one hundredth of 1 percent. Changes of interest rates are often stated in basis points. If an interest rate of 10% increased by 1 bp, it changed to 10.01%. Definition :1 basis point (bp) = (a difference of) 1‱ or 0.01% or 0.1‰ or 10−4 or or 0.0001. :10 bp = (a difference of) 0.1% or 1‰ or 10‱. :100 bp = (a difference of) 1% or 10‰ or 100‱. Basis points are used as a convenient unit of measurement in contexts where percentage differences of less than 1% are discussed. The most common example is interest rates, where differences in interest rates of less than 1% per year are usually meaningful to talk about. For example, a difference of 0.10 percentage points is equivalent to a change of 10 basis points (e.g., a 4.67% rate increases by 10 basis points to 4.77%). In other words, an increase of 100 basis ...
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Basis Point
A basis point (often abbreviated as bp, often pronounced as "bip" or "beep") is one hundredth of 1 percentage point. The related term '' permyriad'' means one hundredth of 1 percent. Changes of interest rates are often stated in basis points. If an interest rate of 10% increased by 1 bp, it changed to 10.01%. Definition :1 basis point (bp) = (a difference of) 1‱ or 0.01% or 0.1‰ or 10−4 or or 0.0001. :10 bp = (a difference of) 0.1% or 1‰ or 10‱. :100 bp = (a difference of) 1% or 10‰ or 100‱. Basis points are used as a convenient unit of measurement A unit of measurement is a definite magnitude of a quantity Quantity or amount is a property that can exist as a multitude or magnitude, which illustrate discontinuity and continuity. Quantities can be compared in terms of "more", ... in contexts where percentage differences of less than 1% are discussed. The most common example is interest rate An interest rate is the amount of interest due per p ...
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Permille
Per mille (from Latin Latin (, or , ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ... , "in each thousand") is an expression that means parts per thousand. Other recognised spellings include per mil, per mill, permil, permill, or permille. The associated sign is written , which looks like a percent sign The percent sign (sometimes per cent sign in British English) is the symbol used to indicate a percentage, a number or ratio as a fraction (mathematics), fraction of 100. Related signs include the permille (per thousand) sign and the Basis p ... with an extra zero or o in the divisor In mathematics Mathematics is an area of knowledge that includes the topics of numbers, formulas and related structures, shapes and the spaces in which they are contained, and quantities ...
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Percentage Point
A percentage point or percent point is the unit (measurement), unit for the Difference (mathematics), arithmetic difference between two percentages. For example, moving up from 40 percent to 44 percent is an increase of 4 percentage points, but a 10-percent increase in the quantity being measured. In literature, the unit is usually either written out, or abbreviated as ''pp'' or ''p.p.'' to avoid ambiguity. After the first occurrence, some writers abbreviate by using just "point" or "points". Differences between percentages and percentage points Consider the following hypothetical example: In 1980, 50 percent of the population smoked, and in 1990 only 40 percent of the population smoked. One can thus say that from 1980 to 1990, the prevalence of smoking decreased by 10 ''percentage points'' (or by 10 percent of the population) or by ''20 percent'' when talking about smokers only - percentages indicate proportionate part of a total. Percentage-point differences are one way to ex ...
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Nuclear Reactor
A nuclear reactor is a device used to initiate and control a fission nuclear chain reaction or nuclear fusion reactions. Nuclear reactors are used at nuclear power plants for electricity generation and in nuclear marine propulsion. Heat from nuclear fission is passed to a working fluid (water or gas), which in turn runs through steam turbines. These either drive a ship's propellers or turn electrical generators' shafts. Nuclear generated steam in principle can be used for industrial process heat or for district heating. Some reactors are used to produce isotopes for Nuclear medicine, medical and industrial radiography, industrial use, or for production of weapons-grade plutonium. , the International Atomic Energy Agency reports there are 422 nuclear power reactors and 223 nuclear research reactors in operation around the world. In the early era of nuclear reactors (1940s), a reactor was known as a nuclear pile or atomic pile (so-called because the graphite moderator blocks of th ...
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Light-water Reactor
The light-water reactor (LWR) is a type of thermal-neutron reactor that uses normal water, as opposed to Pressurized heavy-water reactor, heavy water, as both its coolant and neutron moderator; furthermore a solid form of fissile elements is used as fuel. Thermal-neutron reactors are the most common type of nuclear reactor, and light-water reactors are the most common type of thermal-neutron reactor. There are three varieties of light-water reactors: the pressurized water reactor (PWR), the boiling water reactor (BWR), and (most designs of) the supercritical water reactor (SCWR). History Early concepts and experiments After the discoveries of Nuclear fission, fission, Neutron moderator, moderation and of the theoretical possibility of a nuclear chain reaction, early experimental results rapidly showed that natural uranium could only undergo a sustained chain reaction using graphite or heavy water as a moderator. While the world's first reactors (Chicago Pile-1, CP-1, X-10 Graphi ...
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