pattern of colors - - only a few well - defined colors are involved. ( for more about this, see here. ) by about1910, physicists realized that these patterns indicated changes in the laws of physics as one approached atomic dimensions. atoms consisted of negative light electrons and heavier positive nuclei, and their electric attraction fell with distance at the same rate as gravity, suggesting that electrons orbited in ellipses the way planets orbited the sun. however, an additional effect was predicted : electro - magnetic processes would also make the electrons constantly lose energy by " broadcasting " it into space, like a miniature radio stations. apparently, certain orbits were immune to such losses, and light was only emitted when an electron jumped from one to the other. the simplest pattern of emitted colors was that of hydrogen, for which a remarkably accurate formula actually existed, discovered around 1885 by a swiss high school teacher named johannes balmer. in 1914 the young danish physicist niels bohr ( he and his brother harald, a mathematician, were the stars of denmark ' s soccer team ) discovered what seemed like an explanation for the formulas. bohr showed that balmer ' s formula was obtained naturally and accurately, if one assumed a new law of nature. by that law, electron orbits were stable if the " action variables " associated with their periodic motion were an integral multiple ( i. e. 1, 2, 3... times ) of a new physical constant, one previously known from other " quantum " effects on the atomic scale. paul ehrnfest proposed that that rule extended to other atoms, whose multiple electrons behaved like multiple planets. at this point albert einstein called attention to the pendulum whose string was gradually shortened : its " adiabatic invariant ", the product e times t, was almost constant. could it be, he suggested, that any quantity that was adiabatically conserved in large - scale nature, was exactly conserved on the atomic scale? that led to the early quantum theory of sommerfeld, for hydrogen and hydrogen - like atoms. however, when max born tried it on helium ( two electrons ) his results disagreed with observed colors of helium light. the successful " wave mechanics " theory of schroedinger, heisenberg and born, which in 1925 - 6 replaced bohr ' s naive ( and unexplained ) principle, used a completely different approach. re - emergence of adiabatic invariance : adiabatic invariance again surfaced decades later, in the study of ions and electrons moving in space


simply begin typing or use the editing tools above to add to this article. once you are finished and click submit, your modifications will be sent to our editors for review. atmospheric and cloud processes... greater than 100 percent, with respect to a flat surface of h2o. the development of clouds in such a fashion, which occurs only in a controlled laboratory environment, is referred to as homogeneous nucleation. air containing water vapour with a relative humidity greater than 100 percent, with respect to a flat surface, is referred to as being supersaturated. in the atmosphere,... nucleation processes are classed as heterogeneous or homogeneous. in the former, the surface of some different substance, such as a dust particle or the wall of the container, acts as the centre upon which the first atoms, ions, or molecules of the crystal become properly oriented ; in the latter, a few particles come into correct juxtaposition in the course of their random movement through the... before ice can form, water must supercool and ice crystals nucleate. homogeneous nucleation ( without the influence of foreign particles ) occurs well below the freezing point, at temperatures that are not observed in water bodies. the temperature of heterogeneous nucleation ( nucleation beginning at the surface of foreign particles ) depends on the nature of the particles, but it is generally...... nucleation ). the nuclei consist predominantly of silicate minerals of terrestrial origin, mainly clay minerals and micas. at still lower temperatures, ice may form directly from water vapour ( homogeneous nucleation ). the influence of the atmospheric water vapour depends mainly on its degree of supersaturation with respect to ice. what made you want to look up " homogeneous nucleation "? please share what surprised you most...


simply begin typing or use the editing tools above to add to this article. once you are finished and click submit, your modifications will be sent to our editors for review. aspect of modal logic... p, to be true without a certain proposition, q, being also true ( i. e., if the conjunction of p and not - q is logically impossible ), then it is said that p strictly implies q. an alternative equivalent way of explaining the notion of strict implication is by saying that p strictly implies q if and only if it is necessary that... forms of implication... an attempt to construct a formal relationship more closely akin to the intuitive notion of implication, clarence irving lewis, known for his conceptual pragmatism, introduced in 1932 the notion of strict implication. strict implication was defined as ( a · ), in which ♦ means “ is possible ” or “ is not self - contradictory. ” thus... theory of lewis in logic, lewis criticized contemporary formal systems using material implication and proposed an alternative system of logic based upon strict implication. that is, he rejected systems that do not limit themselves strictly to what is implicit in experience. because concepts arise from experience, in his system no concept is fixed or indispensable, and the abstract categories of traditional... what made you want to look up " strict implication "? please share what surprised you most...


figure 2 : a possible simple check unit consider the check unit shown in figure 2. a, b, and c are buffer registers, probably equal in size to the machine word length. d is a one bit register. a and b can be set by hardware events hi, h2. b can alternatively be set by program pl. c and d are set by program p2, pa. with this checker, a and b can be compared over a field c ; d will then determine whether to freeze on equivalence or non - equivalence. if it is required to freeze when there is a difference between hi and h2 in field c, then d will set to a zero, for example. it is not feasible to position these checkers everywhere they might be wanted. sets of floating plugs and sockets could be provided and the program or engineer could decide where they should be placed. a better method would be a switching matrix so that the eap could connect the checkers it had to the parts of the machine in which it was currently interested. as a speculative matter, if checkers could be connected together under program control then very sophisticated conditions for freezing could be set up. to our basic connections between a large computer system and a maintenance satellite we have now added special hardware to provide detailed information in the form of ' snapshots ' for a perceptive program. we now leave these ideas and consider what has been implemented so far at the science research council atlas computer laboratory by s. r. c. and i. c. t. in collaboration. the atlas engineer ' s assistant this program was mainly implemented by andrew du plessis ( s. r. c., now cambridge university ) with the assistance of the chief maintenance engineer peter dean ( i. c. t. ltd. ) and myself ( see du plessis, 1967 ). its object was to explore the possibilities of a systematic data retrieval system applied to maintenance engineering. most of the program consists of fault location procedures for the different parts of the machine. by running the test programs specified and thus answering the questions asked, some progress towards diagnosing faults will be made. when the program has reached the limit of the assistance it can give ( it will then be pinpointing a faulty area, a particular group of packages, or an individual package ), it can output records of all previous repaired faults which have followed the same diagnostic route. an underlying assumption here is that a component which has failed once is likely to fail again ; in practice this is true enough on


mathematics for electrical engineering and computingby - mary attenborough, phd, the webbery - internet development, co. donegal, ireland. mathematics for electrical engineering and computing embraces many applications of modern mathematics, such as boolean algebra and sets and functions, and also teaches both discrete and continuous systems - particularly vital for digital signal processing ( dsp ). in addition, as most modern engineers are required to study software, material suitable for software engineering - set theory, predicate and prepositional calculus, language and graph theory - is fully integrated into the book. excessive technical detail and language are avoided, recognising that the real requirement for practising engineers is the need to understand the applications of mathematics in everyday engineering contexts. emphasis is given to an appreciation of the fundamental concepts behind the mathematics, for problem solving and undertaking critical analysis of results, whether using a calculator or a computer. the text is backed up by numerous exercises and worked examples throughout, firmly rooted in engineering practice, ensuring that all mathematical theory introduced is directly relevant to real - world engineering. the book includes introductions to advanced topics such as fourier analysis, vector calculus and random processes, also making this a suitable introductory text for second year undergraduates of electrical, electronic and computer engineering, undertaking engineering mathematics courses. the book is supported with a number of free online resources. on the companion website readers will find : * over 60 pages of " background mathematics " reinforcing introductory material for revision purposes in advance of your first year course * plotxpose software ( for equation solving, and drawing graphs of simple functions, their derivatives, integrals and fourier transforms ) * problems and projects ( linking directly to the software ) in addition, for lecturers only, http : / / textbooks. elsevier. com features a complete worked solutions manual for the exercises in the book. dr attenborough is a former senior lecturer in the school of electrical, electronic and information engineering at south bank university. she is currently technical director of the webbery - internet development company, co. donegal, ireland. undergraduate students of electronic and electrical engineering, computing / computer science and software engineering. also suitable to hnc / hnd in the uk. other first year engineering mathematics courses. paperback, 576 pages published : june 2003 - preface. acknowledgement. sets, functions and calculus : sets and functions. functions and their graphs. problem solving and the art of the convincing argument. boolean algebra. trigonometric functions and waves. differentiation. integration. the exponential function. vectors.


the pocket guide to accelerant evidence collection appendix i : glossary of terms for the fire / arson part a. definitions : - a substance used to initiate or promote the spread of fire. the most commonly encountered arson accelerants are ignitable ( flammable or combustible ) liquids. ignitable liquids, such as gasoline and kerosene, generate heavier than air, ignitable vapors at ordinary temperatures, are immiscible ( don ' t mix with water ), and float and sheen ( rainbow coloration ) on surface water. other ignitable liquids, such as ethyl alcohol or isopropyl alcohol, are miscible ( mix well ) and do not float or leave a sheen on water. common structural materials and assemblies and natural or man made substances often readily absorb ignitable liquids. - hydrocarbons are grouped according to their molecular structure. the two major families of hydrocarbons are aliphatic and aromatic. aliphatic hydrocarbons can be either straight chain molecules or branched chain molecules. hydrocarbons can be further classified as alkanes, alkenes, alkynes, and alicyclics. alkanes contain carbon - carbon single bonds ( saturated ) ; examples of alkanes include methane, ethane, and propane. alkenes contain carbon - carbon double bonds ( unsaturated ) ; an example of an alkene is ethylene. alkynes are highly reactive hydrocarbons containing carbon - carbon triple bonds ; an example of an alkyne is acetylene. alicyclic hydrocarbons contain carbon - carbon single bonds and are arranged in a ring structure such as cyclohexane. most of the common ignitable liquid hydrocarbons used as arson accelerants are blended products and contain both aliphatic and aromatic compounds. - the second major family of hydrocarbon molecules have one or more six member ( benzene ) rings of carbon atoms. the simplest aromatic compound is benzene ( c6h6 ). aromatics have a characteristic odor. 4. boiling point - the temperature of a pure liquid at which point its vapor pressure is equal to or slightly greater than atmospheric pressure. boiling occurs when a temperature is reached at which the thermal energy of the particles is great enough to overcome the cohesive forces that hold them in the liquid. most common ignitable liquids consist of mixtures of hydrocarbon compounds ; such mixtures are described as having a "


is reached at which the thermal energy of the particles is great enough to overcome the cohesive forces that hold them in the liquid. most common ignitable liquids consist of mixtures of hydrocarbon compounds ; such mixtures are described as having a " boiling range ". as an example, gasoline is described as having a boiling range of - 45 degrees f to over 400 degrees f. this means that the lightest compound of gasoline boils at - 45 degrees f and the heaviest of the more than 300 individual compounds in gasoline boils at more than 400 degrees f. 5. carbon - a non - metallic element ( periodic table symbol - c ) found nearly pure in nature as in a diamond or graphite or as a component of coal or petroleum. carbon, the sixth most abundant element in the universe, has the unique ability among the elements to be able to react with either metal or non - metal elements. carbon also has the ability to form bonds with other carbon atoms to form long chain or branched molecules. about 3 million carbon compounds are known. substances that contain carbon are called organic compounds and the school of chemistry that studies and uses these compounds is called - the metric and scientific method of measuring temperature was formerly known as centigrade. expressed as degrees ( c ), the freezing point of pure water at sea level is 0 degres c and the boiling point of pure water at sea level is 100 degrees c. to convert from degrees fahrenheit to degrees celsius subtract 32 then divide by 5 / 9th i. e. 68 degrees f - 32 = 36 ; 36 x 5 / 9 = 20 degrees c. 7. combustible liquid - an ignitable liquid having a flash point at or above 100 degres f ( 37. 8 - a rapid ( exothermic ) combustion reaction proceeding through fuel at a sub - sonic speed ( typically less than 3300 feet / second - 1000 meters / second ). - an effect produced by violent, sudden expansion of gases from chemical change such as detonation of an explosive or ignition of a flammable gas, mechanical changes such as in a boiler explosion or atomic changes. 10. explosive limits - ( flammable limits ) the extreme lower & upper concentrations of an air / gas mixture in which combustion or deflagration will be supported. generally, fuels with broad flammable / explosive limits such as acetylene ( 2. 5 % to 80 % by volume ) are considered more hazardous. - the method of measuring temperature where the


table symbol : h. 21. ignition temperature - the minimum temperature to which a substance must be heated in air to ignite independently of the heating source. this temperature is sometimes referred to as the auto - ignition temperature. this temperature is derived from specific laboratory testing of pure substances and serves to classify the hazard presented by the ignitable liquid. the actual ignition temperature of most substances may be somewhat higher than those reported in laboratory - a term that describes substances that do not mix ( e. g. oil and water ). 23. light petroleum distillate - ( c4 - c11 ) a general class of flammable liquids that could include pocket lighter fluids, ethers, some rubber cement solvents and v m & p naphtha. chromatographically, these products contain at least 4 major peaks in the range c4 and c11. ( refer to 24. medium petroleum distillate - ( c8 - c12 ) a general class of flammable or combustible liquids that would include paint thinner ( mineral spirits ), dry cleaning solvents and some brands of charcoal starter fluids. ( refer to chart 1 ) - the ability of two or more substances to mix in all proportions and to form a single, homogeneous phase ( e. g. alcohol and water ). a liquid that can be mixed in all proportions producing a mixture that looks like a single compound ( e. g. alcohol and water ). - a nonflammable ( oxidizing ), gaseous element that is colorless, tasteless and odorless. it is found in a free state in the atmosphere where it makes up 21 % of atmospheric air. oxygen combines with virtually all the other elements except the inert gases. periodic table symbol : o. - oxidation is generally considered any reaction in which electrons are transferred. the substance that gains electrons in the reaction is considered the oxidizing agent and the substance that loses electrons is the reducing material. oxidation and reduction always occur simultaneously. compounds containing oxygen, chlorine, fluorine, etc. are common oxidizing agents. compounds such as potassium nitrate, potassium perchlorate, and calcium hypochlorite are examples of oxidizers commonly encountered in explosive and incendiary compositions. - transformation of a compound into one or more substances by heat alone. this process often precedes combustion. - the process of dispersing one or more solid, liquid, or gaseous substances into another, usually a liquid, forming a homogen


transformation of a compound into one or more substances by heat alone. this process often precedes combustion. - the process of dispersing one or more solid, liquid, or gaseous substances into another, usually a liquid, forming a homogenous mixture. 30. specific gravity - the ratio of weight of a given volume of ignitable liquid compared to an equal volume of fresh water. an ignitable liquid accelerant with a specific gravity less than one will float ; those with specific gravity greater than one will sink. 31. stoichiometric mixture - a stoichmetric mixture is one containing an optimal ratio of fuel and oxygen. gaseous fuel - air mixtures can result in an explosion when a stoichiometric mixture exists. fuel - air mixtures which are capable of resulting in an explosion are typically reported in msds as the lower explosive limit ( lel ) and the upper explosive limit ( uel ). - calibration of physiological damage caused by a poison or toxin. rating is included in part b of this appendix - common ignitable liquids for those products where a rating was reported. | | probable lethal dose for 150 pound person | | 6 - supertoxic | | less than 5mg / kg | | a taste ( less than 7 drops ) | | 5 - extremely toxic | | 5 - 50 | | between 7 drops & 1 tsp. | | 4 - very toxic | | 50 - 500 | | between 1 tsp & 1 ounce | | 3 - moderately toxic | | 0. 5 - 5gm / kg | | between 1 oz & 1 pint | | 2 - slightly toxic | | 5 - 15gm / km | | between 1 pt and 1 quart | | 1 - practically non toxic | | more than 1 quart | 33. vapor density - the ratio of the molecular weight of a given volume of a specific gas or vapor to that of an equal volume of dry air at the same temperature and pressure. a vapor density greater than one will result in a tendency of the vapor to sink. most of the common ignitable liquids have a vapor density greater than one. the closer the vapor density is to the value of air ( one ) the more rapidly that gas will tend to mix with air. higher vapor density vapors tend to resist mixing with air. gasoline, for example, has a vapor density of 3 to 4 times heavier than air. this means concentrated gasoline vapors will ordinarily sink rapidly in still air and


with the aid of lasers, researchers have developed various two - photon absorption ( 2pa ) based applications, which include biological imaging, 3 - dimentional microfabrication, frequency up - converted lasing, optical power limiting, and photodynamic therapy etc. unlike 2pa, five - photon absorption ( 5pa ) related phenomenon, is more difficult to observe due to the low transition probability of the 5pa process. furthermore, the realization of five - photon pumped stimulated emission will be even more difficult because it requires the 5pa to be large enough for creating population inversion in the gain medium. prof. zheng qingdong ’ s group at fujian institute of research on the structure of matter, chinese academy of sciences ( fjirsm ) has reported on the first experimental observation of five - photon induced stimulated emission in collaboration with prof. chen xueyuan ’ s group at fjirsm. by rational molecular design, a multi - photon absorbing material ipps with the molecular configuration of donor - pi - acceptor was prepared and selected from a large number of multi - photon active chromophores. through simultaneous five - photon absorption, stimulated emission from ipps was realized for converting the 2100nm invisible infrared laser into the visible 501nm blue - green laser. at the same time, by direct three - photon absorption, the ipps system exhibited a high net conversion efficiency of 10. 4 percent, which thus enable the realization of novel frequency up - converted lasing in practical device applications. the results have been published in nature photonics. this work is the first real application for five - photon absorption, which belongs to a ninth - order nonlinear process with extremely low probability. for the 5pa process, its 5th - order dependence on the input light intensity would provide a much stronger spatial confinement so that a much higher contrast in imaging can be achieved as compared to lower - order nonlinear absorption.