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wiki_31_chunk_32 | Analytic geometry | In geometry, a normal is an object such as a line or vector that is perpendicular to a given object. For example, in the two-dimensional case, the normal line to a curve at a given point is the line perpendicular to the tangent line to the curve at the point. | wikipedia |
wiki_31_chunk_33 | Analytic geometry | In the three-dimensional case a surface normal, or simply normal, to a surface at a point P is a vector that is perpendicular to the tangent plane to that surface at P. The word "normal" is also used as an adjective: a line normal to a plane, the normal component of a force, the normal vector, etc. The concept of norma... | wikipedia |
wiki_31_chunk_34 | Analytic geometry | External links
Coordinate Geometry topics with interactive animations | wikipedia |
wiki_32_chunk_0 | Analysis of algorithms | In computer science, the analysis of algorithms is the process of finding the computational complexity of algorithms—the amount of time, storage, or other resources needed to execute them. Usually, this involves determining a function that relates the size of an algorithm's input to the number of steps it takes (its ti... | wikipedia |
wiki_32_chunk_1 | Analysis of algorithms | The term "analysis of algorithms" was coined by Donald Knuth. Algorithm analysis is an important part of a broader computational complexity theory, which provides theoretical estimates for the resources needed by any algorithm which solves a given computational problem. These estimates provide an insight into reasonabl... | wikipedia |
wiki_32_chunk_2 | Analysis of algorithms | In theoretical analysis of algorithms it is common to estimate their complexity in the asymptotic sense, i.e., to estimate the complexity function for arbitrarily large input. Big O notation, Big-omega notation and Big-theta notation are used to this end. For instance, binary search is said to run in a number of steps ... | wikipedia |
wiki_32_chunk_3 | Analysis of algorithms | Exact (not asymptotic) measures of efficiency can sometimes be computed but they usually require certain assumptions concerning the particular implementation of the algorithm, called model of computation. A model of computation may be defined in terms of an abstract computer, e.g. Turing machine, and/or by postulating ... | wikipedia |
wiki_32_chunk_4 | Analysis of algorithms | Cost models
Time efficiency estimates depend on what we define to be a step. For the analysis to correspond usefully to the actual run-time, the time required to perform a step must be guaranteed to be bounded above by a constant. One must be careful here; for instance, some analyses count an addition of two numbers a... | wikipedia |
wiki_32_chunk_5 | Analysis of algorithms | Two cost models are generally used:
the uniform cost model, also called uniform-cost measurement (and similar variations), assigns a constant cost to every machine operation, regardless of the size of the numbers involved
the logarithmic cost model, also called logarithmic-cost measurement (and similar variations), a... | wikipedia |
wiki_32_chunk_6 | Analysis of algorithms | A key point which is often overlooked is that published lower bounds for problems are often given for a model of computation that is more restricted than the set of operations that you could use in practice and therefore there are algorithms that are faster than what would naively be thought possible. | wikipedia |
wiki_32_chunk_7 | Analysis of algorithms | Run-time analysis
Run-time analysis is a theoretical classification that estimates and anticipates the increase in running time (or run-time or execution time) of an algorithm as its input size (usually denoted as ) increases. Run-time efficiency is a topic of great interest in computer science: A program can take se... | wikipedia |
wiki_32_chunk_8 | Analysis of algorithms | Shortcomings of empirical metrics Since algorithms are platform-independent (i.e. a given algorithm can be implemented in an arbitrary programming language on an arbitrary computer running an arbitrary operating system), there are additional significant drawbacks to using an empirical approach to gauge the comparative ... | wikipedia |
wiki_32_chunk_9 | Analysis of algorithms | Take as an example a program that looks up a specific entry in a sorted list of size n. Suppose this program were implemented on Computer A, a state-of-the-art machine, using a linear search algorithm, and on Computer B, a much slower machine, using a binary search algorithm. Benchmark testing on the two computers ru... | wikipedia |
wiki_32_chunk_10 | Analysis of algorithms | Based on these metrics, it would be easy to jump to the conclusion that Computer A is running an algorithm that is far superior in efficiency to that of Computer B. However, if the size of the input-list is increased to a sufficient number, that conclusion is dramatically demonstrated to be in error: | wikipedia |
wiki_32_chunk_11 | Analysis of algorithms | Computer A, running the linear search program, exhibits a linear growth rate. The program's run-time is directly proportional to its input size. Doubling the input size doubles the run-time, quadrupling the input size quadruples the run-time, and so forth. On the other hand, Computer B, running the binary search pro... | wikipedia |
wiki_32_chunk_12 | Analysis of algorithms | Orders of growth Informally, an algorithm can be said to exhibit a growth rate on the order of a mathematical function if beyond a certain input size , the function times a positive constant provides an upper bound or limit for the run-time of that algorithm. In other words, for a given input size greater than some ... | wikipedia |
wiki_32_chunk_13 | Analysis of algorithms | Big O notation is a convenient way to express the worst-case scenario for a given algorithm, although it can also be used to express the average-case — for example, the worst-case scenario for quicksort is , but the average-case run-time is . | wikipedia |
wiki_32_chunk_14 | Analysis of algorithms | Empirical orders of growth
Assuming the run-time follows power rule, , the coefficient can be found by taking empirical measurements of run-time } at some problem-size points }, and calculating so that . In other words, this measures the slope of the empirical line on the log–log plot of run-time vs. input size, at ... | wikipedia |
wiki_32_chunk_15 | Analysis of algorithms | It is clearly seen that the first algorithm exhibits a linear order of growth indeed following the power rule. The empirical values for the second one are diminishing rapidly, suggesting it follows another rule of growth and in any case has much lower local orders of growth (and improving further still), empirically, t... | wikipedia |
wiki_32_chunk_16 | Analysis of algorithms | 1 get a positive integer n from input
2 if n > 10
3 print "This might take a while..."
4 for i = 1 to n
5 for j = 1 to i
6 print i * j
7 print "Done!" | wikipedia |
wiki_32_chunk_17 | Analysis of algorithms | A given computer will take a discrete amount of time to execute each of the instructions involved with carrying out this algorithm. The specific amount of time to carry out a given instruction will vary depending on which instruction is being executed and which computer is executing it, but on a conventional computer,... | wikipedia |
wiki_32_chunk_18 | Analysis of algorithms | In the algorithm above, steps 1, 2 and 7 will only be run once. For a worst-case evaluation, it should be assumed that step 3 will be run as well. Thus the total amount of time to run steps 1-3 and step 7 is: | wikipedia |
wiki_32_chunk_19 | Analysis of algorithms | The loops in steps 4, 5 and 6 are trickier to evaluate. The outer loop test in step 4 will execute ( n + 1 )
times (note that an extra step is required to terminate the for loop, hence n + 1 and not n executions), which will consume T4( n + 1 ) time. The inner loop, on the other hand, is governed by the value of j, w... | wikipedia |
wiki_32_chunk_20 | Analysis of algorithms | Altogether, the total time required to run the inner loop body can be expressed as an arithmetic progression: which can be factored as The total time required to run the outer loop test can be evaluated similarly: which can be factored as Therefore, the total run-time for this algorithm is: which reduces to As a rule-o... | wikipedia |
wiki_32_chunk_21 | Analysis of algorithms | A more elegant approach to analyzing this algorithm would be to declare that [T1..T7] are all equal to one unit of time, in a system of units chosen so that one unit is greater than or equal to the actual times for these steps. This would mean that the algorithm's run-time breaks down as follows: | wikipedia |
wiki_32_chunk_22 | Analysis of algorithms | Growth rate analysis of other resources
The methodology of run-time analysis can also be utilized for predicting other growth rates, such as consumption of memory space. As an example, consider the following pseudocode which manages and reallocates memory usage by a program based on the size of a file which that progr... | wikipedia |
wiki_32_chunk_23 | Analysis of algorithms | In this instance, as the file size n increases, memory will be consumed at an exponential growth rate, which is order . This is an extremely rapid and most likely unmanageable growth rate for consumption of memory resources. | wikipedia |
wiki_32_chunk_24 | Analysis of algorithms | Relevance
Algorithm analysis is important in practice because the accidental or unintentional use of an inefficient algorithm can significantly impact system performance. In time-sensitive applications, an algorithm taking too long to run can render its results outdated or useless. An inefficient algorithm can also end... | wikipedia |
wiki_32_chunk_25 | Analysis of algorithms | Constant factors
Analysis of algorithms typically focuses on the asymptotic performance, particularly at the elementary level, but in practical applications constant factors are important, and real-world data is in practice always limited in size. The limit is typically the size of addressable memory, so on 32-bit mach... | wikipedia |
wiki_32_chunk_26 | Analysis of algorithms | This interpretation is primarily useful for functions that grow extremely slowly: (binary) iterated logarithm (log*) is less than 5 for all practical data (265536 bits); (binary) log-log (log log n) is less than 6 for virtually all practical data (264 bits); and binary log (log n) is less than 64 for virtually all prac... | wikipedia |
wiki_32_chunk_27 | Analysis of algorithms | For large data linear or quadratic factors cannot be ignored, but for small data an asymptotically inefficient algorithm may be more efficient. This is particularly used in hybrid algorithms, like Timsort, which use an asymptotically efficient algorithm (here merge sort, with time complexity ), but switch to an asympto... | wikipedia |
wiki_32_chunk_28 | Analysis of algorithms | See also
Amortized analysis
Analysis of parallel algorithms
Asymptotic computational complexity
Best, worst and average case
Big O notation
Computational complexity theory
Master theorem (analysis of algorithms)
NP-Complete
Numerical analysis
Polynomial time
Program optimization
Profiling (computer programm... | wikipedia |
wiki_33_chunk_0 | Chemistry of ascorbic acid | Ascorbic acid is an organic compound with formula , originally called hexuronic acid. It is a white solid, but impure samples can appear yellowish. It dissolves well in water to give mildly acidic solutions. It is a mild reducing agent. | wikipedia |
wiki_33_chunk_1 | Chemistry of ascorbic acid | Ascorbic acid exists as two enantiomers (mirror-image isomers), commonly denoted "" (for "levo") and "" (for "dextro"). The isomer is the one most often encountered: it occurs naturally in many foods, and is one form ("vitamer") of vitamin C, an essential nutrient for humans and many animals. Deficiency of vitamin C c... | wikipedia |
wiki_33_chunk_2 | Chemistry of ascorbic acid | History The antiscorbutic properties of certain foods were demonstrated in the 18th century by James Lind. In 1907, Axel Holst and Theodor Frølich discovered that the antiscorbutic factor was a water-soluble chemical substance, distinct from the one that prevented beriberi. Between 1928 and 1932, Albert Szent-Györgyi i... | wikipedia |
wiki_33_chunk_3 | Chemistry of ascorbic acid | In 1933, sugar chemist Walter Norman Haworth, working with samples of "hexuronic acid" that Szent-Györgyi had isolated from paprika and sent him in the previous year, deduced the correct structure and optical-isomeric nature of the compound, and in 1934 reported its first synthesis. In reference to the compound's antis... | wikipedia |
wiki_33_chunk_4 | Chemistry of ascorbic acid | Chemical properties Acidity
Ascorbic acid is a vinylogous acid and forms the ascorbate anion when deprotonated on one of the hydroxyls. This property is characteristic of reductones: enediols with a carbonyl group adjacent to the enediol group, namely with the group –C(OH)=C(OH)–C(=O)–. The ascorbate anion is stabili... | wikipedia |
wiki_33_chunk_5 | Chemistry of ascorbic acid | For this reason, ascorbic acid is much more acidic than would be expected if the compound contained only isolated hydroxyl groups. Salts
The ascorbate anion forms salts, such as sodium ascorbate, calcium ascorbate, and potassium ascorbate. Esters
Ascorbic acid can also react with organic acids as an alcohol forming est... | wikipedia |
wiki_33_chunk_6 | Chemistry of ascorbic acid | The ascorbate ion is the predominant species at typical biological pH values. It is a mild reducing agent and antioxidant. It is oxidized with loss of one electron to form a radical cation and then with loss of a second electron to form dehydroascorbic acid. It typically reacts with oxidants of the reactive oxygen spec... | wikipedia |
wiki_33_chunk_7 | Chemistry of ascorbic acid | RO• + → RO− + C6H7O → ROH + C6H6O6 On exposure to oxygen, ascorbic acid will undergo further oxidative decomposition to various products including diketogulonic acid, xylonic acid, threonic acid and oxalic acid. | wikipedia |
wiki_33_chunk_8 | Chemistry of ascorbic acid | Reactive oxygen species are damaging to animals and plants at the molecular level due to their possible interaction with nucleic acids, proteins, and lipids. Sometimes these radicals initiate chain reactions. Ascorbate can terminate these chain radical reactions by electron transfer. The oxidized forms of ascorbate ar... | wikipedia |
wiki_33_chunk_9 | Chemistry of ascorbic acid | Ascorbic acid and its sodium, potassium, and calcium salts are commonly used as antioxidant food additives. These compounds are water-soluble and, thus, cannot protect fats from oxidation: For this purpose, the fat-soluble esters of ascorbic acid with long-chain fatty acids (ascorbyl palmitate or ascorbyl stearate) can... | wikipedia |
wiki_33_chunk_10 | Chemistry of ascorbic acid | Food additive
The main use of -ascorbic acid and its salts is as food additives, mostly to combat oxidation. It is approved for this purpose in the EU with E number E300, USA, Australia, and New Zealand) Dietary supplement
Another major use of -ascorbic acid is as dietary supplement. Niche, non-food uses | wikipedia |
wiki_33_chunk_11 | Chemistry of ascorbic acid | Ascorbic acid is easily oxidized and so is used as a reductant in photographic developer solutions (among others) and as a preservative.
In fluorescence microscopy and related fluorescence-based techniques, ascorbic acid can be used as an antioxidant to increase fluorescent signal and chemically retard dye photobleach... | wikipedia |
wiki_33_chunk_12 | Chemistry of ascorbic acid | Synthesis
Natural biosynthesis of vitamin C occurs in many plants, and animals, by a variety of processes. Industrial preparation | wikipedia |
wiki_33_chunk_13 | Chemistry of ascorbic acid | Eighty percent of the world's supply of ascorbic acid is produced in China.
Ascorbic acid is prepared in industry from glucose in a method based on the historical Reichstein process. In the first of a five-step process, glucose is catalytically hydrogenated to sorbitol, which is then oxidized by the microorganism Acet... | wikipedia |
wiki_33_chunk_14 | Chemistry of ascorbic acid | A more biotechnological process, first developed in China in the 1960s, but further developed in the 1990s, bypasses the use of acetone-protecting groups. A second genetically modified microbe species, such as mutant Erwinia, among others, oxidises sorbose into 2-ketogluconic acid (2-KGA), which can then undergo ring-... | wikipedia |
wiki_33_chunk_15 | Chemistry of ascorbic acid | There exists a -ascorbic acid, which does not occur in nature but can be synthesized artificially. To be specific, -ascorbate is known to participate in many specific enzyme reactions that require the correct enantiomer (-ascorbate and not -ascorbate). -Ascorbic acid has a specific rotation of [α] = +23°. Determinatio... | wikipedia |
wiki_33_chunk_16 | Chemistry of ascorbic acid | The popular iodometry approach uses iodine in the presence of a starch indicator. Iodine is reduced by ascorbic acid, and, when all the ascorbic acid has reacted, the iodine is then in excess, forming a blue-black complex with the starch indicator. This indicates the end-point of the titration. As an alternative, asco... | wikipedia |
wiki_33_chunk_17 | Chemistry of ascorbic acid | This iodometric method has been revised to exploit reaction of ascorbic acid with iodate and iodide in acid solution. Electrolyzing the solution of potassium iodide produces iodine, which reacts with ascorbic acid. The end of process is determined by potentiometric titration in a manner similar to Karl Fischer titratio... | wikipedia |
wiki_33_chunk_18 | Chemistry of ascorbic acid | Another alternative uses N-bromosuccinimide (NBS) as the oxidizing agent, in the presence of potassium iodide and starch. The NBS first oxidizes the ascorbic acid; when the latter is exhausted, the NBS liberates the iodine from the potassium iodide, which then forms the blue-black complex with starch. See also
Colour... | wikipedia |
wiki_33_chunk_19 | Chemistry of ascorbic acid | IPCS Poisons Information Monograph (PIM) 046
Interactive 3D-structure of vitamin C with details on the x-ray structure Organic acids
Antioxidants
Dietary antioxidants
Coenzymes
Corrosion inhibitors
Furanones
Vitamers
Vitamin C
Biomolecules
3-Hydroxypropenals | wikipedia |
wiki_34_chunk_0 | Audio signal processing | Audio signal processing is a subfield of signal processing that is concerned with the electronic manipulation of audio signals. Audio signals are electronic representations of sound waves—longitudinal waves which travel through air, consisting of compressions and rarefactions. The energy contained in audio signals is t... | wikipedia |
wiki_34_chunk_1 | Audio signal processing | History
The motivation for audio signal processing began at the beginning of the 20th century with inventions like the telephone, phonograph, and radio that allowed for the transmission and storage of audio signals. Audio processing was necessary for early radio broadcasting, as there were many problems with studio-to... | wikipedia |
wiki_34_chunk_2 | Audio signal processing | Major developments in digital audio coding and audio data compression include differential pulse-code modulation (DPCM) by C. Chapin Cutler at Bell Labs in 1950, linear predictive coding (LPC) by Fumitada Itakura (Nagoya University) and Shuzo Saito (Nippon Telegraph and Telephone) in 1966, adaptive DPCM (ADPCM) by P. C... | wikipedia |
wiki_34_chunk_3 | Audio signal processing | Analog signals An analog audio signal is a continuous signal represented by an electrical voltage or current that is analogous to the sound waves in the air. Analog signal processing then involves physically altering the continuous signal by changing the voltage or current or charge via electrical circuits. Historicall... | wikipedia |
wiki_34_chunk_4 | Audio signal processing | A digital representation expresses the audio waveform as a sequence of symbols, usually binary numbers. This permits signal processing using digital circuits such as digital signal processors, microprocessors and general-purpose computers. Most modern audio systems use a digital approach as the techniques of digital ... | wikipedia |
wiki_34_chunk_5 | Audio signal processing | Processing methods and application areas include storage, data compression, music information retrieval, speech processing, localization, acoustic detection, transmission, noise cancellation, acoustic fingerprinting, sound recognition, synthesis, and enhancement (e.g. equalization, filtering, level compression, echo an... | wikipedia |
wiki_34_chunk_6 | Audio signal processing | Audio signal processing is used when broadcasting audio signals in order to enhance their fidelity or optimize for bandwidth or latency. In this domain, the most important audio processing takes place just before the transmitter. The audio processor here must prevent or minimize overmodulation, compensate for non-linea... | wikipedia |
wiki_34_chunk_7 | Audio signal processing | Audio synthesis is the electronic generation of audio signals. A musical instrument that accomplishes this is called a synthesizer. Synthesizers can either imitate sounds or generate new ones. Audio synthesis is also used to generate human speech using speech synthesis. Audio effects | wikipedia |
wiki_34_chunk_8 | Audio signal processing | Audio effects alter the sound of a musical instrument or other audio source. Common effects include distortion, often used with electric guitar in electric blues and rock music; dynamic effects such as volume pedals and compressors, which affect loudness; filters such as wah-wah pedals and graphic equalizers, which mod... | wikipedia |
wiki_34_chunk_9 | Audio signal processing | Musicians, audio engineers and record producers use effects units during live performances or in the studio, typically with electric guitar, bass guitar, electronic keyboard or electric piano. While effects are most frequently used with electric or electronic instruments, they can be used with any audio source, such as... | wikipedia |
wiki_35_chunk_0 | Analytical chemistry | Analytical chemistry studies and uses instruments and methods used to separate, identify, and quantify matter. In practice, separation, identification or quantification may constitute the entire analysis or be combined with another method. Separation isolates analytes. Qualitative analysis identifies analytes, while qu... | wikipedia |
wiki_35_chunk_1 | Analytical chemistry | Analytical chemistry consists of classical, wet chemical methods and modern, instrumental methods. Classical qualitative methods use separations such as precipitation, extraction, and distillation. Identification may be based on differences in color, odor, melting point, boiling point, solubility, radioactivity or reac... | wikipedia |
wiki_35_chunk_2 | Analytical chemistry | Analytical chemistry is also focused on improvements in experimental design, chemometrics, and the creation of new measurement tools. Analytical chemistry has broad applications to medicine, science, and engineering. History Analytical chemistry has been important since the early days of chemistry, providing methods fo... | wikipedia |
wiki_35_chunk_3 | Analytical chemistry | The first instrumental analysis was flame emissive spectrometry developed by Robert Bunsen and Gustav Kirchhoff who discovered rubidium (Rb) and caesium (Cs) in 1860. Most of the major developments in analytical chemistry take place after 1900. During this period instrumental analysis becomes progressively dominant in ... | wikipedia |
wiki_35_chunk_4 | Analytical chemistry | The separation sciences follow a similar time line of development and also become increasingly transformed into high performance instruments. In the 1970s many of these techniques began to be used together as hybrid techniques to achieve a complete characterization of samples. | wikipedia |
wiki_35_chunk_5 | Analytical chemistry | Starting in approximately the 1970s into the present day analytical chemistry has progressively become more inclusive of biological questions (bioanalytical chemistry), whereas it had previously been largely focused on inorganic or small organic molecules. Lasers have been increasingly used in chemistry as probes and e... | wikipedia |
wiki_35_chunk_6 | Analytical chemistry | Modern analytical chemistry is dominated by instrumental analysis. Many analytical chemists focus on a single type of instrument. Academics tend to either focus on new applications and discoveries or on new methods of analysis. The discovery of a chemical present in blood that increases the risk of cancer would be a di... | wikipedia |
wiki_35_chunk_7 | Analytical chemistry | Classical methods Although modern analytical chemistry is dominated by sophisticated instrumentation, the roots of analytical chemistry and some of the principles used in modern instruments are from traditional techniques, many of which are still used today. These techniques also tend to form the backbone of most unde... | wikipedia |
wiki_35_chunk_8 | Analytical chemistry | Inorganic qualitative analysis generally refers to a systematic scheme to confirm the presence of certain aqueous ions or elements by performing a series of reactions that eliminate ranges of possibilities and then confirms suspected ions with a confirming test. Sometimes small carbon-containing ions are included in su... | wikipedia |
wiki_35_chunk_9 | Analytical chemistry | Quantitative analysis is the measurement of the quantities of particular chemical constituents present in a substance. Quantities can be measured by mass (gravimetric analysis) or volume (volumetric analysis). Gravimetric analysis Gravimetric analysis involves determining the amount of material present by weighing the ... | wikipedia |
wiki_35_chunk_10 | Analytical chemistry | Titration involves the addition of a reactant to a solution being analyzed until some equivalence point is reached. Often the amount of material in the solution being analyzed may be determined. Most familiar to those who have taken chemistry during secondary education is the acid-base titration involving a color-chang... | wikipedia |
wiki_35_chunk_11 | Analytical chemistry | Spectroscopy measures the interaction of the molecules with electromagnetic radiation. Spectroscopy consists of many different applications such as atomic absorption spectroscopy, atomic emission spectroscopy, ultraviolet-visible spectroscopy, x-ray spectroscopy, fluorescence spectroscopy, infrared spectroscopy, Raman ... | wikipedia |
wiki_35_chunk_12 | Analytical chemistry | Mass spectrometry measures mass-to-charge ratio of molecules using electric and magnetic fields. There are several ionization methods: electron ionization, chemical ionization, electrospray ionization, fast atom bombardment, matrix assisted laser desorption/ionization, and others. Also, mass spectrometry is categorized... | wikipedia |
wiki_35_chunk_13 | Analytical chemistry | Electroanalytical methods measure the potential (volts) and/or current (amps) in an electrochemical cell containing the analyte. These methods can be categorized according to which aspects of the cell are controlled and which are measured. The four main categories are potentiometry (the difference in electrode potent... | wikipedia |
wiki_35_chunk_14 | Analytical chemistry | Calorimetry and thermogravimetric analysis measure the interaction of a material and heat. Separation Separation processes are used to decrease the complexity of material mixtures. Chromatography, electrophoresis and field flow fractionation are representative of this field. | wikipedia |
wiki_35_chunk_15 | Analytical chemistry | Hybrid techniques
Combinations of the above techniques produce a "hybrid" or "hyphenated" technique. Several examples are in popular use today and new hybrid techniques are under development. For example, gas chromatography-mass spectrometry, gas chromatography-infrared spectroscopy, liquid chromatography-mass spectro... | wikipedia |
wiki_35_chunk_16 | Analytical chemistry | Hyphenated separation techniques refer to a combination of two (or more) techniques to detect and separate chemicals from solutions. Most often the other technique is some form of chromatography. Hyphenated techniques are widely used in chemistry and biochemistry. A slash is sometimes used instead of hyphen, especially... | wikipedia |
wiki_35_chunk_17 | Analytical chemistry | The visualization of single molecules, single cells, biological tissues, and nanomaterials is an important and attractive approach in analytical science. Also, hybridization with other traditional analytical tools is revolutionizing analytical science. Microscopy can be categorized into three different fields: optica... | wikipedia |
wiki_35_chunk_18 | Analytical chemistry | Devices that integrate (multiple) laboratory functions on a single chip of only millimeters to a few square centimeters in size and that are capable of handling extremely small fluid volumes down to less than picoliters. Errors Error can be defined as numerical difference between observed value and true value. The expe... | wikipedia |
wiki_35_chunk_19 | Analytical chemistry | where
is the absolute error.
is the true value.
is the observed value.
Error of a measurement is an inverse measure of accurate measurement i.e. smaller the error greater the accuracy of the measurement. Errors can be expressed relatively. Given the relative error(): The percent error can also be calculated: If ... | wikipedia |
wiki_35_chunk_20 | Analytical chemistry | A general method for analysis of concentration involves the creation of a calibration curve. This allows for determination of the amount of a chemical in a material by comparing the results of an unknown sample to those of a series of known standards. If the concentration of element or compound in a sample is too high ... | wikipedia |
wiki_35_chunk_21 | Analytical chemistry | Internal standards
Sometimes an internal standard is added at a known concentration directly to an analytical sample to aid in quantitation. The amount of analyte present is then determined relative to the internal standard as a calibrant. An ideal internal standard is an isotopically-enriched analyte which gives rise ... | wikipedia |
wiki_35_chunk_22 | Analytical chemistry | Standard addition
The method of standard addition is used in instrumental analysis to determine the concentration of a substance (analyte) in an unknown sample by comparison to a set of samples of known concentration, similar to using a calibration curve. Standard addition can be applied to most analytical techniques a... | wikipedia |
wiki_35_chunk_23 | Analytical chemistry | Noise can arise from environmental factors as well as from fundamental physical processes. Thermal noise Thermal noise results from the motion of charge carriers (usually electrons) in an electrical circuit generated by their thermal motion. Thermal noise is white noise meaning that the power spectral density is consta... | wikipedia |
wiki_35_chunk_24 | Analytical chemistry | Shot noise is a type of electronic noise that occurs when the finite number of particles (such as electrons in an electronic circuit or photons in an optical device) is small enough to give rise to statistical fluctuations in a signal. Shot noise is a Poisson process and the charge carriers that make up the current fol... | wikipedia |
wiki_35_chunk_25 | Analytical chemistry | Flicker noise is electronic noise with a 1/ƒ frequency spectrum; as f increases, the noise decreases. Flicker noise arises from a variety of sources, such as impurities in a conductive channel, generation, and recombination noise in a transistor due to base current, and so on. This noise can be avoided by modulation of... | wikipedia |
wiki_35_chunk_26 | Analytical chemistry | Environmental noise arises from the surroundings of the analytical instrument. Sources of electromagnetic noise are power lines, radio and television stations, wireless devices, compact fluorescent lamps and electric motors. Many of these noise sources are narrow bandwidth and therefore can be avoided. Temperature and ... | wikipedia |
wiki_35_chunk_27 | Analytical chemistry | Analytical chemistry has applications including in forensic science, bioanalysis, clinical analysis, environmental analysis, and materials analysis. Analytical chemistry research is largely driven by performance (sensitivity, detection limit, selectivity, robustness, dynamic range, linear range, accuracy, precision, an... | wikipedia |
wiki_35_chunk_28 | Analytical chemistry | Great effort is being put in shrinking the analysis techniques to chip size. Although there are few examples of such systems competitive with traditional analysis techniques, potential advantages include size/portability, speed, and cost. (micro total analysis system (µTAS) or lab-on-a-chip). Microscale chemistry redu... | wikipedia |
wiki_35_chunk_29 | Analytical chemistry | Many developments improve the analysis of biological systems. Examples of rapidly expanding fields in this area are genomics, DNA sequencing and related research in genetic fingerprinting and DNA microarray; proteomics, the analysis of protein concentrations and modifications, especially in response to various stresso... | wikipedia |
wiki_35_chunk_30 | Analytical chemistry | Analytical chemistry has played critical roles in the understanding of basic science to a variety of practical applications, such as biomedical applications, environmental monitoring, quality control of industrial manufacturing, forensic science, and so on. | wikipedia |
wiki_35_chunk_31 | Analytical chemistry | The recent developments of computer automation and information technologies have extended analytical chemistry into a number of new biological fields. For example, automated DNA sequencing machines were the basis to complete human genome projects leading to the birth of genomics. Protein identification and peptide sequ... | wikipedia |
wiki_35_chunk_32 | Analytical chemistry | Analytical chemistry has been an indispensable area in the development of nanotechnology. Surface characterization instruments, electron microscopes and scanning probe microscopes enable scientists to visualize atomic structures with chemical characterizations. See also Important publications in analytical chemistry
L... | wikipedia |
wiki_35_chunk_33 | Analytical chemistry | Gurdeep, Chatwal Anand (2008). Instrumental Methods of Chemical Analysis Himalaya Publishing House (India)
Ralph L. Shriner, Reynold C. Fuson, David Y. Curtin, Terence C. Morill: The systematic identification of organic compounds - a laboratory manual, Verlag Wiley, New York 1980, 6. edition, .
Bettencourt da Sil... | wikipedia |
wiki_35_chunk_34 | Analytical chemistry | External links Infografik and animation showing the progress of analytical chemistry
aas Atomic Absorption Spectrophotometer Materials science | wikipedia |
wiki_36_chunk_0 | Analog computer | An analog computer or analogue computer is a type of computer that uses the continuous variation aspect of physical phenomena such as electrical, mechanical, or hydraulic quantities (analog signals) to model the problem being solved. In contrast, digital computers represent varying quantities symbolically and by discre... | wikipedia |
wiki_36_chunk_1 | Analog computer | Analog computers were widely used in scientific and industrial applications even after the advent of digital computers, because at the time they were typically much faster, but they started to become obsolete as early as the 1950s and 1960s, although they remained in use in some specific applications, such as aircraft ... | wikipedia |
wiki_36_chunk_2 | Analog computer | Timeline of analog computers Precursors This is a list of examples of early computation devices considered precursors of the modern computers. Some of them may even have been dubbed 'computers' by the press, though they may fail to fit modern definitions. | wikipedia |
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