When was the Heckscher–Ohlin model developed?
Bertil Ohlin
In 1930 Ohlin succeeded Eli Heckscher, his teacher, as a professor of economics, at the Stockholm School of Economics. In 1933 Ohlin published a work that made him world-renowned, "Interregional and International Trade". In this Ohlin built an economic theory of international trade from earlier work by Heckscher and his own doctoral thesis. It is now known as the Heckscher–Ohlin model, one of the standard model economists use to debate trade theory.
Action potential
Mathematical and computational models are essential for understanding the action potential, and offer predictions that may be tested against experimental data, providing a stringent test of a theory. The most important and accurate of the early neural models is the Hodgkin–Huxley model, which describes the action potential by a coupled set of four ordinary differential equations (ODEs). Although the Hodgkin–Huxley model may be a simplification with few limitations compared to the realistic nervous membrane as it exists in nature, its complexity has inspired several even-more-simplified models, such as the Morris–Lecar model and the FitzHugh–Nagumo model, both of which have only two coupled ODEs. The properties of the Hodgkin–Huxley and FitzHugh–Nagumo models and their relatives, such as the Bonhoeffer–van der Pol model, have been well-studied within mathematics, computation and electronics. However the simple models of generator potential and action potential fail to accurately reproduce the near threshold neural spike rate and spike shape, specifically for the mechanoreceptors like the Pacinian corpuscle. More modern research has focused on larger and more integrated systems; by joining action-potential models with models of other parts of the nervous system (such as dendrites and synapses), researchers can study neural computation and simple reflexes, such as escape reflexes and others controlled by central pattern generators.
Modular form
The theory of modular forms was developed in four periods: first in connection with the theory of elliptic functions, in the first part of the nineteenth century; then by Felix Klein and others towards the end of the nineteenth century as the automorphic form concept became understood (for one variable); then by Erich Hecke from about 1925; and then in the 1960s, as the needs of number theory and the formulation of the modularity theorem in particular made it clear that modular forms are deeply implicated.
Tscherne classification
This classification system was developed by Harald Tscherne and Hans-Jörg Oestern in 1982 at the Hannover Medical School (Hanover, Germany) to classify both open and closed fractures. This classification system is based on the physiological concept that the higher the kinetic energy imparted on the bone, the higher the kinetic energy imparted on the soft tissue. It also serves as a tool to guide management and to predict clinical outcomes. It also serves as a communication tool in research and in clinical presentations.
Heckscher–Ohlin model
In a simple model, both countries produce two commodities. Each commodity in turn is made using two factors of production. The production of each commodity requires input from both factors of production—capital (K) and labor (L). The technologies of each commodity is assumed to exhibit constant returns to scale (CRS). CRS technologies implies that when inputs of both capital and labor is multiplied by a factor of "k", the output also multiplies by a factor of "k". For example, if both capital and labor inputs are doubled, output of the commodities is doubled. In other terms the production function of both commodities is "homogeneous of degree 1".
Neural oscillation
A model of a biological neuron is a mathematical description of the properties of nerve cells, or neurons, that is designed to accurately describe and predict its biological processes. The most successful and widely used model of neurons, the Hodgkin–Huxley model, is based on data from the squid giant axon. It is a set of nonlinear ordinary differential equations that approximates the electrical characteristics of a neuron, in particular the generation and propagation of action potentials. The model is very accurate and detailed and Hodgkin and Huxley received the 1963 Nobel Prize in physiology or medicine for this work.
Depolarizing prepulse
In the early 1950s Drs. Hodgkin and Huxley performed experiments on the squid giant axon, and in the process developed a model (the Hodgkin–Huxley model) for sodium channel conductance. It was found that the conductance may be expressed as:
Clark–Wilson model
The model was described in a 1987 paper ("A Comparison of Commercial and Military Computer Security Policies") by David D. Clark and David R. Wilson. The paper develops the model as a way to formalize the notion of information integrity, especially as compared to the requirements for multilevel security (MLS) systems described in the Orange Book. Clark and Wilson argue that the existing integrity models such as Biba (read-up/write-down) were better suited to enforcing data integrity rather than information confidentiality. The Biba models are more clearly useful in, for example, banking classification systems to prevent the untrusted modification of information and the tainting of information at higher classification levels, respectively. In contrast, Clark–Wilson is more clearly applicable to business and industry processes in which the integrity of the information content is paramount at any level of classification (although the authors stress that all three models are obviously of use to both government and industry organizations).
UC Irvine Institute of Transportation Studies
1986 – Will Recker and Michael McNally proposed the theoretical background for the first operational activity-based model, STARCHILD
1986 – Will Recker and Michael McNally presented part II of their STARCHILD model
1987 – Thomas Golob, Will Recker, and John Leonard studied truck-related accidents using log-linear models and found that durations of accidents were log-normally distributed
1992 – Kenneth Small proposed a revenue distribution model to make congestion pricing practical and politically viable
1992 – Genevieve Giuliano reviewed congestion pricing policies and suggested politically acceptable alternatives
1994 – Charles Lave and Patrick Elias examined the 65 mph speed limit systematically at the statewide level and showed that the change from 55 mph reduced fatality rates
1995 – Kelvin Cheu and Stephen Ritchie developed an incident detection algorithm based on inductive loop data and an artificial neural network method
1995 – Kenneth Small measured the costs of air pollution in Los Angeles from motor vehicles
1995 – Jayakrishnan, Wei Tsai, and Anthony Chen developed a dynamic traffic assignment model with network loading that made use of DYNASMART, the first mesoscopic traffic simulation model
1996 – Michael Zhang, Stephen Ritchie, and Will Recker formulated the ramp metering control as a dynamic optimal control problem and presented solution methods and validation
1997 – Thomas Golob and Michael McNally used a structural model to explain interactions between household members
1998 – Randall Crane empirically tested the hypothesis that urban design can influence travel, showing that no such evidence could be found from local household travel survey and GIS data
1999 – Carlos Sun, Stephen Ritchie, Kevin Tsai, and Jayakrishnan formulated the vehicle reidentification problem as a lexicographic optimization problem and demonstrated robust performance
2000 – David Brownstone explored the advantages of merging stated preference and revealed preference data in an empirical study to evaluate alternative fuel vehicle market penetration
2000 – Thomas Golob developed a model that jointly generates activity participation, travel time, and trip generation
Heckscher–Ohlin model
If the two countries have separate currencies, this does not affect the model in any way—purchasing power parity applies. Since there are no transaction costs or currency issues the law of one price applies to both commodities, and consumers in either country pay exactly the same price for either good.
Harry Gordon Johnson
Johnson made many contributions to the development of Hecksher-Ohlin theory and until the 1970s according to Moggeridge, was the second most quoted trade theorist after Paul Samuelson. Johnson also helped to found the monetary approach to the balance of payments and wrote many high quality surveys of monetary economics that helped to clarify the issues in question. Despite being perhaps the most prolific economist of the modern era, Johnson's star has waned as is evidenced by the significant fall (discussed in Moggeridge's biography) in citations to his work in the past decade.
Lieb–Liniger model
A model of a gas of particles moving in one dimension and satisfying Bose–Einstein statistics was introduced in 1963 in order to study whether the available approximate theories of such gases, specifically Bogoliubov's theory, would conform to the actual properties of the model gas. The model is based on a well defined Schrödinger Hamiltonian for particles interacting with each other via a two-body potential, and all the eigenfunctions and eigenvalues of this Hamiltonian can, in principle, be calculated exactly. Sometimes it is called one dimensional Bose gas with delta interaction. It also can be considered as quantum non-linear Schrödinger equation.
Robert S. Mulliken
Up to this point, the primary way to calculate the electronic structure of molecules was based on a calculation by Walter Heitler and Fritz London on the hydrogen molecule (H) in 1927. With the conception of hybridized atomic orbitals by John C. Slater and Linus Pauling, which rationalized observed molecular geometries, the method was based on the premise that the bonds in any molecule could be described in a manner similar to the bond in H, namely, as overlapping atomic orbitals centered on the atoms involved. Since it corresponded to chemists' ideas of localized bonds between pairs of atoms, this method (called the Valence-Bond (VB) or Heitler-London-Slater-Pauling (HLSP) method), was very popular. However, particularly in attempting to calculate the properties of excited states (molecules that have been excited by some source of energy), the VB method does not always work well. With its description of the electron wave functions in molecules as delocalized molecular orbitals that possess the same symmetry as the molecule, Hund and Mulliken's molecular-orbital method, including contributions by John Lennard-Jones, proved to be more flexible and applicable to a vast variety of types of molecules and molecular fragments, and has eclipsed the valence-bond method. As a result of this development, he received the Nobel Prize in Chemistry in 1966.
Heckscher–Ohlin model
Differences in labour abundance would not produce a difference in "relative" factor abundance (in relation to mobile capital) because the labour/capital ratio would be identical everywhere. (A large country would receive twice as much investment as a small one, for instance, maximizing capitalist's return on investment).
Black–Scholes model
and
Heckscher–Ohlin model
From the middle of the 19th century to 1930s, giant flow of immigration took place from Europe to North America. It is estimated that more than 60 million people crossed the Atlantic Ocean. Some politicians worried if these immigrants may cause various troubles (including cultural conflicts). For those politicians HO-theory provided a good reason “in support of both restrictions on labor migration and free trade in goods”.
Heckscher–Ohlin model
Unemployment is the vital question in any trade conflict. Heckscher–Ohlin theory excludes unemployment by the very formulation of the model, in which all factors (including labour) are employed in the production.
Stolper–Samuelson theorem
It was derived in 1941 from within the framework of the Heckscher–Ohlin model by Wolfgang Stolper and Paul Samuelson, but has subsequently been derived in less restricted models. As a term, it is applied to all cases where the effect is seen. Ronald W. Jones and José Scheinkman (1977) show that under very general conditions the factor returns change with output prices as predicted by the theorem. If considering the change in real returns under increased international trade a robust finding of the theorem is that returns to the scarce factor will go down, ceteris paribus. An additional robust corollary of the theorem is that a compensation to the scarce factor exists which will overcome this effect and make increased trade Pareto optimal.
The original Heckscher–Ohlin model was a two-factor model with a labour market specified by a single number. Therefore, the early versions of the theorem could make no predictions about the effect on the unskilled labour force in a high-income country under trade liberalization. However, more sophisticated models with multiple classes of worker productivity have been shown to produce the Stolper–Samuelson effect within each class of labour: Unskilled workers producing traded goods in a high-skill country will be worse off as international trade increases, because, relative to the world market in the good they produce, an unskilled first world production-line worker is a less abundant factor of production than capital.
Scientist–practitioner model
David Shakow created the first version of the model and introduced it to the academic community. From the years of 1941 until 1949, Shakow presented the model to a series of committees where the core tenets developed further. The model changed minimally from its original version because it was received extremely well at all of the conferences. At the Boulder Conference of 1949, this model of training for clinical graduate programs was purposed. Here, it received accreditation by the psychological community and the American Psychological Association.
Heckscher–Ohlin model
Modern econometric estimates have shown the model to perform poorly, however, and adjustments have been suggested, most importantly the assumption that technology is not the same everywhere. This change would mean abandoning the pure H–O model.
Heckscher–Ohlin model
The Leontief paradox, presented by Wassily Leontief in 1953, found that the U.S. (the most capital-abundant country in the world by any criterion) exported labor-intensive commodities and imported capital-intensive commodities, contrary to the Heckscher–Ohlin theory.
Modular Ocean Model
MOM owes its genesis to work at GFDL in the late 1960s by Kirk Bryan and Mike Cox. This code, along with a version generated at GFDL and UCLA/NCAR by Bert Semtner, is the ancestor of many of the level-coordinate ocean model codes run around the world today. In the late 1980s, Ron Pacanowski, Keith Dixon, and Tony Rosati at GFDL rewrote the Bryan-Cox-Semtner code in a modular form, enabling different options and configurations to be more easily generated and new physical parameterizations to be more easily included. This version, released in December 1990, became known as Modular Ocean Model v1.0 (MOM1). Further development by Pacanowski, aided by Charles Goldberg and encouraged by community feedback, led to the release of v2.0 (MOM2) in 1995. Pacanowski and Stephen Griffies released v3.0 (MOM3) in 1999. Griffies, Matthew Harrison, Rosati and Pacanowski, with considerable input from a scientific community of hundreds of users, resulted in significant evolution of the code released as v4.0 (MOM4) in 2003. An update, v4.1 (MOM4p1) was released by Griffies in 2009, as was the latest version v5.0 (MOM5), which was released in 2012.
Electronic oscillator
Mathematical conditions for feedback oscillations, now called the Barkhausen criterion, were derived by Heinrich Georg Barkhausen in 1921. The first analysis of a nonlinear electronic oscillator model, the Van der Pol oscillator, was done by Balthasar van der Pol in 1927. He showed that the stability of the oscillations (limit cycles) in actual oscillators was due to the nonlinearity of the amplifying device. He originated the term "relaxation oscillation" and was first to distinguish between linear and relaxation oscillators. Further advances in mathematical analysis of oscillation were made by Hendrik Wade Bode and Harry Nyquist in the 1930s. In 1969 K. Kurokawa derived necessary and sufficient conditions for oscillation in negative-resistance circuits, which form the basis of modern microwave oscillator design.
Color model
In an attempt to accommodate more traditional and intuitive color mixing models, computer graphics pioneers at PARC and NYIT developed the HSV model in the mid-1970s, formally described by Alvy Ray Smith in the August 1978 issue of "Computer Graphics". In the same issue, Joblove and Greenberg described the HSL model—whose dimensions they labeled "hue", "relative chroma", and "intensity"—and compared it to HSV. Their model was based more upon how colors are organized and conceptualized in human vision in terms of other color-making attributes, such as hue, lightness, and chroma; as well as upon traditional color mixing methods—e.g., in painting—that involve mixing brightly colored pigments with black or white to achieve lighter, darker, or less colorful colors.
Heckscher–Ohlin model
Capital goods take different forms. It may take the form of a machine-tool such as lathe, the form of a transfer-machine, which you can see under the belt-conveyors. It may take the form of oil or iron core. Despite these facts, capital in the Hechscher–Ohlin model is assumed as homogeneous and transferable to any form if necessary. This assumption is not only far from the reality, but also it includes logical flaw. Capital has a measure, just like anything has weight. How can an amount of various goods be measured?
Heckscher–Ohlin
Heckscher–Ohlin can refer to:
Heckman correction
The Heckman correction (the two-stage method, Heckman's lambda or the Heckit method) is any of a number of related statistical methods developed by James Heckman at the University of Chicago in 1976 to 1979 which allow the researcher to correct for selection bias. Selection bias problems are endemic to applied econometric problems, which make Heckman’s original technique, and subsequent refinements by both himself and others, indispensable to applied econometricians. Heckman received the Economics Nobel Prize in 2000 for his work in this field.
Heckscher–Ohlin model
Standard Heckscher–Ohlin theory assumes the same production function for all countries. This implies that all firms are identical. The theoretical consequence is that there is no room for firms in the H–O model. By contrast, the New Trade Theory emphasizes that firms are heterogeneous.
Wolf–Hirschhorn syndrome
The minimum birth incidence has been calculated as 1 in 95,896.
Wolf–Hirschhorn syndrome was first described in 1961 by Americans Herbert L. Cooper and Kurt Hirschhorn and, thereafter, gained worldwide attention by publications by the German Ulrich Wolf, and Hirschhorn and their co-workers, specifically their articles in the German scientific magazine "Humangenetik".
Roper–Logan–Tierney model of nursing
First developed in 1980, this model is based upon work by Nancy Roper in 1976. It is the most widely used nursing model in the United Kingdom. The model is based loosely upon the activities of daily living that evolved from the work of Virginia Henderson in 1966.
The latest book edited by these women 2001 is their culminating and completing work, in which they upgrade their model based on their view of societal needs. The original purpose of the model was to be an assessment used throughout the patient's care, but it has become the norm in UK nursing to use it only as a checklist on admission. It is often used to assess how a patient's life has changed due to illness or admission to hospital rather than as a way of planning for increased independence and quality of life.
Heckscher–Ohlin model
"See also": "The Ricardian Theory of International Trade"
Bateson–Dobzhansky–Muller model
The Bateson-Dobzhansky-Muller Model, also known as Dobzhansky-Muller Model, is a model of the evolution of genetic incompatibility, important in understanding the evolution of reproductive isolation during speciation and the role of natural selection in bringing it about. The theory was first described by William Bateson in 1909, then independently described by Theodosius Dobzhansky in 1934, and later elaborated in different forms by Herman Muller, H. Allen Orr and Sergey Gavrilets.
Heckscher–Ohlin model
In this example, the marginal return to an extra unit of capital is higher in the fishing industry, assuming units of fish ("F") and arable output ("A") have equal value. The more capital-abundant country may gain by developing its fishing fleet at the expense of its arable farms. Conversely, the workers available in the relatively labor-abundant country can be employed relatively more efficiently in arable farming.
Threshold potential
Along with reconstructing the action potential in the 1950s, Alan Lloyd Hodgkin and Andrew Huxley were also able to experimentally determine the mechanism behind the threshold for excitation. It is known as the Hodgkin–Huxley model. Through use of voltage clamp techniques on a squid giant axon, they discovered that excitable tissues generally exhibit the phenomenon that a certain membrane potential must be reached in order to fire an action potential. Since the experiment yielded results through the observation of ionic conductance changes, Hodgkin and Huxley used these terms to discuss the threshold potential. They initially suggested that there must be a discontinuity in the conductance of either sodium or potassium, but in reality both conductances tended to vary smoothly along with the membrane potential.
Heckscher–Ohlin model
For example, a country where capital and land are abundant but labor is scarce has a comparative advantage in goods that require lots of capital and land, but little labor—grains. If capital and land are abundant, their prices are low. As they are the main factors in the production of grain, the price of grain is also low—and thus attractive for both local consumption and export. Labor-intensive goods on the other hand are very expensive to produce since labor is scarce and its price is high. Therefore, the country is better off importing those goods.
Erich Hückel
Hückel is most famous for developing the Hückel method of approximate molecular orbital (MO) calculations on π electron systems, a simplified quantum-mechanical method to deal with planar unsaturated organic molecules. In 1930 he proposed a σ/π separation theory to explain the restricted rotation of alkenes (compounds containing a C=C double bond). This model extended a 1929 interpretation of the bonding in triplet oxygen by Lennard-Jones. According to Hückel, only the ethene σ bond is axially symmetric about the C-C axis, but the π bond is not; this restricts rotation. In 1931 he generalized his analysis by formulating both valence bond (VB) and molecular orbital (MO) descriptions of benzene and other cycloconjugated hydrocarbons. Although undeniably a cornerstone of organic chemistry, Hückel's concepts were undeservedly unrecognized for two decades. His lack of communication skills contributed. The famous Hückel 4n+2 rule for determining whether ring molecules composed of C=C bonds would show aromatic properties was first stated clearly by Doering in a 1951 article on tropolone. Tropolone had been recognised as an aromatic molecule by Dewar in 1945.
Johnson–Holmquist damage model
There are two variations of the Johnson-Holmquist model that are used to model the impact performance of ceramics under ballistically delivered loads. These models were developed by Gordon R. Johnson and Timothy J. Holmquist in the 1990s with the aim of facilitating predictive numerical simulations of ballistic armor penetration. The first version of the model is called the 1992 Johnson-Holmquist 1 (JH-1) model. This original version was developed to account for large deformations but did not take into consideration progressive damage with increasing deformation; though the multi-segment stress-strain curves in the model can be interpreted as incorporating damage implicitly. The second version, developed in 1994, incorporated a damage evolution rule and is called the Johnson-Holmquist 2 (JH-2) model or, more accurately, the Johnson-Holmquist damage material model.
Animal model of ischemic stroke
One of the most commonly used animal models of hypoxic ischemia was originally described by Levine in 1960 and later refined by Rice et al., in 1981. This approach is useful to study hypoxic ischemia in the developing brain, since newborn rat pups are utilized in this model. Briefly, 7 day old rat pups undergo a permanent unilateral carotid artery ligation with a subsequent 3 hour exposure to a hypoxic environment (8% oxygen). This model creates a unilateral infarct in the hemisphere ipsilateral to the ligation, since the hypoxia alone is subthreshold for injury at this age. The area of injury is typically concentrated in periventricular regions of the brain, especially cortical and hippocampal areas.
Heckscher–Ohlin model
New Trade theorists challenge the assumption of diminishing returns to scale, and some argue that using protectionist measures to build up a huge industrial base in certain industries would then allow those sectors to dominate the world market via a network effect.
Hodgkin–Huxley model
The Hodgkin–Huxley model, or conductance-based model, is a mathematical model that describes how action potentials in neurons are initiated and propagated. It is a set of nonlinear differential equations that approximates the electrical characteristics of excitable cells such as neurons and cardiac myocytes. It is a continuous time model, unlike, for example, the Rulkov map.
International trade theory
In this model labor mobility among industries is possible while capital is assumed to be immobile in the short run. Thus, this model can be interpreted as a short-run version of the Heckscher-Ohlin model. The "specific factors" name refers to the assumption that in the short run, specific factors of production such as physical capital are not easily transferable between industries. The theory suggests that if there is an increase in the price of a good, the owners of the factor of production specific to that good will profit in real terms
Black–Scholes model
and
Models of neural computation
The Hodgkin–Huxley model, widely regarded as one of the great achievements of 20th-century biophysics, describes how action potentials in neurons are initiated and propagated in axons via voltage-gated ion channels. It is a set of nonlinear ordinary differential equations that were introduced by Alan Lloyd Hodgkin and Andrew Huxley in 1952 to explain the results of voltage clamp experiments on the squid giant axon. Analytic solutions do not exist, but the Levenberg–Marquardt algorithm, a modified Gauss–Newton algorithm, is often used to fit these equations to voltage-clamp data.
Internationalization
This econometric find was the result of Professor Wassily W. Leontief's attempt to test the Heckscher-Ohlin theory empirically. In 1954, Leontief found that the U.S. (the most capital-abundant country in the world by any criteria) exported labor-intensive commodities and imported capital-intensive commodities, in contradiction with Heckscher-Ohlin theory.
Automorphic form
Before this very general setting was proposed (around 1960), there had already been substantial developments of automorphic forms other than modular forms. The case of Γ a Fuchsian group had already received attention before 1900 (see below). The Hilbert modular forms (also called Hilbert-Blumenthal forms) were proposed not long after that, though a full theory was long in coming. The Siegel modular forms, for which "G" is a symplectic group, arose naturally from considering moduli spaces and theta functions. The post-war interest in several complex variables made it natural to pursue the idea of automorphic form in the cases where the forms are indeed complex-analytic. Much work was done, in particular by Ilya Piatetski-Shapiro, in the years around 1960, in creating such a theory. The theory of the Selberg trace formula, as applied by others, showed the considerable depth of the theory. Robert Langlands showed how (in generality, many particular cases being known) the Riemann-Roch theorem could be applied to the calculation of dimensions of automorphic forms; this is a kind of "post hoc" check on the validity of the notion. He also produced the general theory of Eisenstein series, which corresponds to what in spectral theory terms would be the 'continuous spectrum' for this problem, leaving the cusp form or discrete part to investigate. From the point of view of number theory, the cusp forms had been recognised, since Srinivasa Ramanujan, as the heart of the matter.
Princeton Ocean Model
The model code was originally developed at Princeton University (G. Mellor and Alan Blumberg) in collaboration with Dynalysis of Princeton (H. James Herring, Richard C. Patchen). The model incorporates the Mellor–Yamada turbulence scheme developed in the early 1970s by George Mellor and Ted Yamada; this turbulence sub-model is widely used by oceanic and atmospheric models. At the time, early computer ocean models such as the Bryan–Cox model (developed in the late 1960s at the Geophysical Fluid Dynamics Laboratory, GFDL, and later became the Modular Ocean Model, MOM)), were aimed mostly at coarse-resolution simulations of the large-scale ocean circulation, so there was a need for a numerical model that can handle high-resolution coastal ocean processes. The Blumberg–Mellor model (which later became POM) thus included new features such as free surface to handle tides, sigma vertical coordinates (i.e., terrain-following) to handle complex topographies and shallow regions, a curvilinear grid to better handle coastlines, and a turbulence scheme to handle vertical mixing. At the early 1980s the model was used primarily to simulate estuaries such as the Hudson–Raritan Estuary (by Leo Oey) and the Delaware Bay (Boris Galperin), but also first attempts to use a sigma coordinate model for basin-scale problems have started with the coarse resolution model of the Gulf of Mexico (Blumberg and Mellor) and models of the Arctic Ocean (with the inclusion of ice-ocean coupling by Lakshmi Kantha and Sirpa Hakkinen).
Data model
In the 1970s G.M. Nijssen developed "Natural Language Information Analysis Method" (NIAM) method, and developed this in the 1980s in cooperation with Terry Halpin into Object-Role Modeling (ORM). However, it was Terry Halpin's 1989 PhD thesis that created the formal foundation on which Object-Role Modeling is based.
Product life-cycle theory
The Product Life Cycle Theory is an economic theory that was developed by Raymond Vernon in response to the failure of the Heckscher-Ohlin model to explain the observed pattern of international trade. The theory suggests that early in a product's life-cycle all the parts and labor associated with that product come from the area where it was invented. After the product becomes adopted and used in the world markets, production gradually moves away from the point of origin. In some situations, the product becomes an item that is imported by its original country of invention. A commonly used example of this is the invention, growth and production of the personal computer with respect to the United States.
AND Corporation
The first version of the HNeT Application Development System was released in 1990 and published in 1991 which contained a number of example applications, based on the complex valued phase coherence/decoherence process. Among these applications were the complex valued Hopfield network or complex associative memory, which was discovered by S. Jankowski in 1996 according to A. Hirose et al. The concepts initially developed and applied within the HNeT technology form the basis for several related academic fields; these referred to by the acronyms Quantum neural network (QNN), Holographic associative memory (HAM), Complex Associative Memory (CAM) and Complex Valued Neural Networks (CVNN).
Heckler &amp; Koch Mark 23
After several tests, Heckler & Koch and Colt submissions were selected to move to phase I of the OHWS program in August 1991. They were awarded developmental contracts to produce 30 systems. At the time the program was beginning, HK was studying what aspects were most desirable in handguns for the U.S. civilian market. They came up with a design that had these features including reliability, durability, affordability, and others by February 1991. Colt however essentially drew upon existing technologies for their submission called the Colt OHWS. They used an M1911 frame that could accept a 10-round magazine, the decocking mechanism from the Colt Double Eagle, and the rotating barrel locking system from the All American 2000. The barrel of the Colt OHWS could not directly attach a suppressor, so a mounting was added to a rail in front of the handguard.
Chemical bonding model
Molecular orbitals were first introduced by Friedrich Hund and Robert S. Mulliken in 1927 and 1928. The linear combination of atomic orbitals or "LCAO" approximation for molecular orbitals was introduced in 1929 by Sir John Lennard-Jones. Linear combinations of atomic orbitals (LCAO) can be used to estimate the molecular orbitals that are formed upon bonding between the molecule's constituent atoms. Similar to an atomic orbital, a Schrödinger equation, which describes the behavior of an electron, can be constructed for a molecular orbital as well. Linear combinations of atomic orbitals, or the sums and differences of the atomic wavefunctions, provide approximate solutions to the Hartree–Fock equations which correspond to the independent-particle approximation of the molecular Schrödinger equation.
Keystroke-level model
In human–computer interaction, the keystroke-level model (KLM) predicts how long it will take an expert user to accomplish a routine task without errors using an interactive computer system. It was proposed by Stuart K. Card, Thomas P. Moran and Allen Newell in 1980 in the "Communications of the ACM" and published in their book "The Psychology of Human-Computer Interaction" in 1983, which is considered as a classic in the HCI field. The foundations were laid in 1974, when Card and Moran joined the Palo Alto Research Center (PARC) and created a group named Applied Information-Processing Psychology Project (AIP) with Newell as a consultant aiming to create an applied psychology of human-computer interaction. The keystroke-level model is still relevant today, which is shown by the recent research about mobile phones and touchscreens (see Adaptions).
Nicholson–Bailey model
The Nicholson–Bailey model was developed in the 1930s to describe the population dynamics of a coupled host-parasitoid system. It is named after Alexander John Nicholson and Victor Albert Bailey. Host-parasite and prey-predator systems can also be represented with the Nicholson-Bailey model. The model is closely related to the Lotka–Volterra model, which describes the dynamics of antagonistic populations (preys and predators) using differential equations.
Heckscher–Ohlin model
The assumption of constant returns to scale CRS is useful because it exhibits a diminishing returns in a factor. Under constant returns to scale, doubling both capital and labor leads to a doubling of the output. Since outputs are increasing in both factors of production, doubling capital while holding labor constant leads to less than doubling of an output. Diminishing returns to capital and diminishing returns to labor are crucial to the Stolper–Samuelson theorem.
Heckscher–Ohlin model
The "Stolper–Samuelson theorem" concerns nominal rents and wages. The Magnification effect on prices considers the effect of output-goods price-changes on the real return to capital and labor. This is done by dividing the nominal rates with a price index, but took thirty years to develop completely because of the theoretical complexity involved.
Redlich–Kwong equation of state
However, its modeling of real behavior is not sufficient for many applications, and by 1949, had fallen out of favor, with the Beattie–Bridgeman and Benedict–Webb–Rubin equation equations of state being used preferentially, both which contain more parameters than the Van der Waals equation. The Redlich–Kwong equation was developed by Redlich and Kwong while they were both working for the Shell Development Company at Emeryville, California. Kwong had begun working at Shell in 1944, where he met Otto Redlich when he joined the group in 1945. The equation arose out of their work at Shell - they wanted an easy, algebraic way to relate the pressures, volumes, and temperatures of the gasses they were working with - mostly non-polar and slightly polar hydrocarbons (the Redlich–Kwong equation is less accurate for hydrogen-bonding gases). It was presented jointly in Portland, Oregon at the "Symposium on Thermodynamics and Molecular Structure of Solutions" in 1948, as part of the 14th Meeting of the American Chemical Society. The success of the Redlich–Kwong equation in modeling many real gasses accurately demonstrate that a cubic, two-parameter equation of state can give adequate results, if it is properly constructed. After they demonstrated the viability of such equations, many others created equations of similar form to try to improve on the results of Redlich and Kwong.
Heckscher–Ohlin model
Exports of a capital-abundant country come from capital-intensive industries, and labour-abundant countries import such goods, exporting labour-intensive goods in return. Competitive pressures within the H–O model produce this prediction fairly straightforwardly. Conveniently, this is an easily testable hypothesis.
Heckscher–Ohlin model
This assumption means that producing the same output of either commodity "could" be done with the same level of capital and labour in either country. Actually, it would be inefficient to use the same balance in either country (because of the relative availability of either input factor) but, in principle this would be possible. Another way of saying this is that the per-capita productivity is the same in both countries in the same technology with identical amounts of capital.
Geiger–Müller tube
The modern halogen-filled G–M tube was invented by Sidney H. Liebson in 1947 and has several advantages over the older tubes with organic mixtures. The halogen tube discharge takes advantage of a metastable state of the inert gas atom to more-readily ionize a halogen molecule than an organic vapor, enabling the tube to operate at much lower voltages, typically 400–600 volts instead of 900–1200 volts. While halogen-quenched tubes have greater plateau voltage slopes compared to organic-quenched tubes (an undesirable quality), they have a vastly longer life than tubes quenched with organic compounds. This is because the organic vapor is gradually destroyed by the discharge process (giving organic-quenched tubes a useful life of around 10 events), while the halogen ions can recombine over time (giving halogen-quenched tubes an effectively unlimited lifetime for most uses, although they will still eventually fail at some point due to other ionization-initiated processes that limit the lifetime of all Geiger tubes). For these reasons, the halogen-quenched tube is now the most common.
Normalization model
The normalization model is an influential model of responses of neurons in primary visual cortex. David Heeger developed the model in the early 1990s, and later refined it together with Matteo Carandini and J. Anthony Movshon. The model involves a divisive stage. In the numerator is the output of the classical receptive field. In the denominator, a constant plus a measure of local stimulus contrast. Although the normalization model was initially developed to explain responses in the primary visual cortex, normalization is now thought to operate throughout the visual system, and in many other sensory modalities and brain regions, including the representation of odors, the modulatory effects of visual attention, the encoding of value, and the integration of multisensory information. Its presence in such a diversity of neural systems in multiple species, from invertebrates to mammals, suggests that normalization serves as a canonical neural computation.
Heckscher–Ohlin theorem
The critical assumption of the Heckscher–Ohlin model is that the two countries are identical, except for the difference in resource endowments. This also implies that the aggregate preferences are the same. The relative abundance in capital will cause the capital-abundant country to produce the capital-intensive good cheaper than the labor-abundant country and vice versa.
Heckscher–Ohlin theorem
The Leontief paradox, presented by Wassily Leontief in 1951, found that the U.S. (the most capital-abundant country in the world by any criterion) exported labor-intensive commodities and imported capital-intensive commodities, in apparent contradiction with the Heckscher–Ohlin theorem. However, if labor is separated into two distinct factors, skilled labor and unskilled labor, the Heckscher–Ohlin theorem is more accurate. The U.S. tends to export skilled-labor-intensive goods, and tends to import unskilled-labor-intensive goods.
International trade theory
In the early 1900s, a theory of international trade was developed by two Swedish economists, Eli Heckscher and Bertil Ohlin. This theory has subsequently become known as the Heckscher–Ohlin model (H–O model). The results of the H–O model are that the pattern of international trade is determined by differences in factor endowments. It predicts that countries will export those goods that make intensive use of locally abundant factors and will import goods that make intensive use of factors that are locally scarce.
Memory
The multi-store model (also known as Atkinson–Shiffrin memory model) was first described in 1968 by Atkinson and Shiffrin.
Bertil Ohlin
The model was a break-through because it showed how comparative advantage might relate to general features of a country's capital and labor, and how these features might change through time. The model provided a basis for later work on the effects of protection on real wages, and has been fruitful in producing predictions and analysis; Ohlin himself used the model to derive the Heckscher–Ohlin theorem, that nations would specialize in industries most able to utilize their mix of national resources efficiently. Today, the theory has been largely disproved, yet it is still a useful framework by which to understand international trade.
Back-and-forth method
According to Hodges (1993):
While the theorem on countable densely ordered sets is due to Cantor (1895), the back-and-forth method with which it is now proved was developed by Huntington (1904) and Hausdorff (1914). Later it was applied in other situations, most notably by Roland Fraïssé in model theory.
Tiltrotor
The idea of constructing Vertical Take-Off and Landing (VTOL) aircraft using helicopter-like rotors at the wingtips originated in the 1930s. The first design resembling modern tiltrotors was patented by George Lehberger in May 1930, but he did not further develop the concept. In World War II, a German prototype, the Focke-Achgelis Fa 269, was developed starting in 1942, but never flew. Platt and LePage patented the PL-16, the first American tiltrotor aircraft. However, the company shut down in August 1946 due to lack of capital.
Stephen Ross (economist)
Ross is best known for the development of the arbitrage pricing theory (mid-1970s) as well as for his role in developing the binomial options pricing model (1979; also known as the Cox–Ross–Rubinstein model). He was an initiator of the fundamental financial concept of risk-neutral pricing. In 1985 he contributed to the creation of the Cox–Ingersoll–Ross model for interest rate dynamics. Such theories have become an important part of the paradigm known as neoclassical finance.
Ogden (hyperelastic model)
The Ogden material model is a hyperelastic material model used to describe the non-linear stress–strain behaviour of complex materials such as rubbers, polymers, and biological tissue. The model was developed by Raymond Ogden in 1972. The Ogden model, like other hyperelastic material models, assumes that the material behaviour can be described by means of a strain energy density function, from which the stress–strain relationships can be derived.
Heckscher–Ohlin model
The original H–O model assumed that the only difference between countries was the relative abundances of labour and capital. The original Heckscher–Ohlin model contained two countries, and had two commodities that could be produced. Since there are two (homogeneous) factors of production this model is sometimes called the "2×2×2 model".
Heckscher–Ohlin model
New Trade Theory analyses individual enterprises and plants in an international competitive situation. The classical trade theory—i.e., the Heckscher–Ohlin model—has no enterprises in mind. The new trade theory treats enterprises in an industry as identical entities. New New Trade Theory gives focus on the diversity of enterprises. It is a fact that some enterprises engage in export and some that do not. Some enterprises invest directly in the foreign country in order to produce and sell in that country. Some other enterprises engage only in export. Why does this kind of differences occur? New Trade Theory tries to find out the reasons of these well observed facts.
N-vector model
In statistical mechanics, the "n"-vector model or O("n") model is a simple system of interacting spins on a crystalline lattice. It was developed by H. Eugene Stanley as a generalization of the Ising model, XY model and Heisenberg model. In the "n"-vector model, "n"-component unit-length classical spins formula_1 are placed on the vertices of a lattice. The Hamiltonian of the "n"-vector model is given by:
Heckscher–Ohlin model
Ricardian theory is now extended in a general form to include not only labor, but also inputs of materials and intermediate goods. In this sense, it is much more general and plausible than the Heckscher–Ohlin model and escapes the logical problems such as capital as endowments, which is, in reality, produced goods.
IS–LM model
The model was developed by John Hicks in 1937, and later extended by Alvin Hansen, as a mathematical representation of Keynesian macroeconomic theory. Between the 1940s and mid-1970s, it was the leading framework of macroeconomic analysis. While it has been largely absent from macroeconomic research ever since, it is still a backbone conceptual introductory tool in many macroeconomics textbooks.
Black model
The Black model (sometimes known as the Black-76 model) is a variant of the Black–Scholes option pricing model. Its primary applications are for pricing options on future contracts, bond options, Interest rate cap and floors, and swaptions. It was first presented in a paper written by Fischer Black in 1976.
Heckscher–Ohlin model
Countries have natural advantages in the production of various commodities in relation to one another, so this is an "unrealistic" simplification designed to highlight the effect of variable factors. This meant that the original H–O model produced an alternative explanation for free trade to Ricardo's, rather than a complementary one; in reality, both effects may occur due to differences in technology and factor abundances.
Quantitative models of the action potential
A hybrid of the Hodgkin–Huxley and FitzHugh–Nagumo models was developed by Morris and Lecar in 1981, and applied to the muscle fiber of barnacles. True to the barnacle's physiology, the Morris–Lecar model replaces the voltage-gated sodium current of the Hodgkin–Huxley model with a voltage-dependent calcium current. There is no inactivation (no "h" variable) and the calcium current equilibrates instantaneously, so that again, there are only two time-dependent variables: the transmembrane voltage "V" and the potassium gate probability "n". The bursting, entrainment and other mathematical properties of this model have been studied in detail.
Lee–Carter model
The Lee–Carter model was introduced by Ronald D. Lee and Lawrence Carter in 1992 with the article "Modeling and Forecasting the Time Series of U.S. Mortality," (Journal of the American Statistical Association 87 (September): 659–671). The model grew out of their work in the late 1980s and early 1990s attempting to use inverse projection to infer rates in historical demography. The model has been used by the United States Social Security Administration, the US Census Bureau, and the United Nations. It has become the most widely used mortality forecasting technique in the world today.
OSTO System Model
The OSTO System Model is based on the “Organization Performance Model” which has been developed, tested and published by David P. Hanna in 1988 in his 
time as a consultant for Procter & Gamble. Further important participants in this development include Clark/Krone 1972, Krone 1974 and Krug 1992. 
Later on, the model has been further developed and systemized for science by Heijo Rieckmann (Klagenfurt University) and Klaus Henning (RWTH Aachen University) as well as for systemic consulting of organizations by Renate Henning.
Heckscher–Ohlin model
Free and competitive trade makes factor prices converge along with traded goods prices. The FPE theorem is the most significant conclusion of the H–O model, but also has found the least agreement with the economic evidence. Neither the rental return to capital, nor the wage rates seem to consistently converge between trading partners at different levels of development.
Hodgkin–Huxley model
Alan Lloyd Hodgkin and Andrew Fielding Huxley described the model in 1952 to explain the ionic mechanisms underlying the initiation and propagation of action potentials in the squid giant axon. They received the 1963 Nobel Prize in Physiology or Medicine for this work.
General circulation model
In 1956, Norman Phillips developed a mathematical model that could realistically depict monthly and seasonal patterns in the troposphere. It became the first successful climate model. Following Phillips's work, several groups began working to create GCMs. The first to combine both oceanic and atmospheric processes was developed in the late 1960s at the NOAA Geophysical Fluid Dynamics Laboratory. By the early 1980s, the United States' National Center for Atmospheric Research had developed the Community Atmosphere Model; this model has been continuously refined. In 1996, efforts began to model soil and vegetation types. Later the Hadley Centre for Climate Prediction and Research's HadCM3 model coupled ocean-atmosphere elements. The role of gravity waves was added in the mid-1980s. Gravity waves are required to simulate regional and global scale circulations accurately.
Heckscher–Ohlin model
Usually by a system of prices. But prices depend on profit rate. In the Heckscher–Ohlin model, the rate of profit is determined according to how abundant capital is. If capital is scarce, it has a high rate of profit. If it is abundant, the profit rate is low. Here is a logical circle. Before the profit rate is determined, the amount of capital is not measured. This logical difficulty was the subject of academic controversy many years ago—sometimes called the Cambridge Capital Controversies. The conclusion of the controversies was that the concept of homogeneous capital was untenable. Heckscher–Ohlin theorists ignore all these stories without providing any explanation how capital is measured theoretically.
Heckscher–Ohlin model
The standard Heckscher–Ohlin model assumes that the production functions are identical for all countries concerned. This means that all countries are in the same level of production and have the same technology, yet this is highly unrealistic. Technological gap between developed and developing countries is the main concern for the development of poor countries. The standard Heckscher–Ohlin model ignores all these vital factors when one wants to consider development of less developed countries in the international context. Even between developed countries, technology differs from industry to industry and firm to firm base. Indeed, this is the very basis of the competition between firms, inside the country and across the country. See the New Trade Theory in this article below.
Solomon Mikhlin
In mathematical elasticity theory, Mikhlin was concerned by three themes: the plane problem (mainly from 1932 to 1935), the theory of shells (from 1954) and the Cosserat spectrum (from 1967 to 1973). Dealing with the plane elasticity problem, he proposed two methods for its solution in multiply connected domains. The first one is based upon the so-called complex Green's function and the reduction of the related boundary value problem to integral equations. The second method is a certain generalization of the classical Schwarz algorithm for the solution of the Dirichlet problem in a given domain by splitting it in simpler problems in smaller domains whose union is the original one. Mikhlin studied its convergence and gave applications to special applied problems. He proved existence theorems for the fundamental problems of plane elasticity involving inhomogeneous anisotropic media: these results are collected in the book . Concerning the theory of shells, there are several Mikhlin's articles dealing with it. He studied the error of the approximate solution for shells, similar to plane plates, and found out that this error is small for the so-called purely rotational state of stress. As a result of his study of this ploblem, Mikhlin also gave a new (invariant) form of the basic equations of the theory. He also proved a theorem on perturbations of positive operators in a Hilbert space which let him to obtain an error estimate for the problem of approximating a sloping shell by a plane plate. Mikhlin studied also the spectrum of the operator pencil of the classical linear elastostatic operator or Navier–Cauchy operator
where formula_2 is the displacement vector, formula_3 is the vector laplacian, formula_4 is the gradient, formula_5 is the divergence and formula_6 is a Cosserat eigenvalue. The full description of the spectrum and the proof of the completeness of the system of eigenfunctions are also due to Mikhlin, and partly to V.G. Maz'ya in their only joint work.
Atkin–Lehner theory
In mathematics, Atkin–Lehner theory is part of the theory of modular forms, in which the concept of newform is defined in such a way that the theory of Hecke operators can be extended to higher level. A newform is a cusp form 'new' at a given "level" "N", where the levels are the nested congruence subgroups:
Black–Scholes model
where now
History of numerical weather prediction
The Urban Airshed Model, a regional forecast model for the effects of air pollution and acid rain, was developed by a private company in the US in 1970. Development of this model was taken over by the Environmental Protection Agency and improved in the mid to late 1970s using results from a regional air pollution study. While developed in California, this model was later used in other areas of North America, Europe and Asia during the 1980s. The Community Multiscale Air Quality model (CMAQ) is an open source air quality model run within the United States in conjunction with the NAM mesoscale model since 2004. The first operational air quality model in Canada, Canadian Hemispheric and Regional Ozone and NOx System (CHRONOS), began to be run in 2001. It was replaced with the Global Environmental Multiscale model – Modelling Air quality and Chemistry (GEM-MACH) model in November 2009.
Heckler &amp; Koch USP
Design work on a new family of pistols commenced in September 1989 focused primarily on the United States commercial and law enforcement markets. USP prototypes participated in rigorous testing alongside H&K's entry in the Offensive Handgun Weapon System (OHWS) program requested by the U.S. Special Operations Command (USSOCOM) and which would later result in the Mk 23 Mod 0. The USP prototypes were then refined in 1992, based on input from the OHWS trials, and the design was finalized in December of the same year. The USP was formally introduced in January 1993 with the USP40 model (the base version) chambered for the increasingly popular .40 S&W cartridge, followed soon by the USP9 (using the 9×19mm Parabellum cartridge), and in May 1995—the USP45 (caliber .45 ACP).
In contrast to the ambitious and innovative P7, P9S, and VP70Z designs, the USP uses a more conventional Browning-style cam-locked action, similar to that used in the Hi-Power - but with a polymer frame.
Molecular orbital theory
Erich Hückel applied molecular orbital theory to unsaturated hydrocarbon molecules starting in 1931 with his Hückel molecular orbital (HMO) method for the determination of MO energies for pi electrons, which he applied to conjugated and aromatic hydrocarbons. This method provided an explanation of the stability of molecules with six pi-electrons such as benzene.
Harris Mayer
The best-known and most widely used model of absorption bands in atmospheric opacity is due to the work of Richard M. Goody in 1952, and the model was initially known as the Goody random model. It was later discovered that Mayer's work at Los Alamos, which was published in 1947, had made similar calculations. Many sources therefore now call the model the Mayer-Goody model or the Mayer-Goody statistical model. Mayer, however, stated that he believed the model should most properly be credited to Teller. Arthur N. Cox developed a method for computing stellar opacity that was also influential and was based primarily on Mayer's 1947 work, which Mayer initially called the "Mayer Independent Electron" method for calculations at high temperatures and the "Ionic" method at lower temperatures.
Heckscher–Ohlin model
See also Intra-industry trade.
Intra-industry trade
Yet, Donald Davis believed that both the Heckscher–Ohlin and Ricardian models were still relevant in explaining intra-industry trade. He developed the Heckscher-Ohlin-Ricardo model, which showed that even with constant returns to scale that intra-industry trade could still occur under the traditional setting. The Heckscher-Ohlin-Ricardo model explained that countries of identical factor endowments would still trade due to differences in technology, as this would encourage specialisation and therefore trade, in exactly the same matter that was set out in the Ricardian model.
Internationalization
The Heckscher-Ohlin model (H-O model), also known as the "factors proportions development", is a general equilibrium mathematical model of international trade, developed by Eli Heckscher and Bertil Ohlin at the Stockholm School of Economics. It builds on David Ricardo's theory of comparative advantage by predicting patterns of commerce and production based on the factor endowments of a trading region. The model essentially says that countries will export products that utilize their abundant and cheap factor(s) of production and import products that utilize the countries' scarce factor(s).
Molecular model
In the 1600s, Johannes Kepler speculated on the symmetry of snowflakes and also on the close packing of spherical objects such as fruit (this problem remained unsolved until very recently). The symmetrical arrangement of closely packed spheres informed theories of molecular structure in the late 1800s, and many theories of crystallography and solid state inorganic structure used collections of equal and unequal spheres to simulate packing and predict structure.
John Dalton represented compounds as aggregations of circular atoms, and although Johann Josef Loschmidt did not create physical models, his diagrams based on circles are two-dimensional analogues of later models. August Wilhelm von Hofmann is credited with the first physical molecular model around 1860 (Fig. 1). Note how the size of the carbon appears smaller than the hydrogen. The importance of stereochemistry was not then recognised and the model is essentially topological (it should be a 3-dimensional tetrahedron).
Black–Scholes model
where now
Heckscher–Ohlin model
However, if labor is separated into two distinct factors, skilled labor and unskilled labor, the Heckscher–Ohlin theorem is more accurate. The U.S. tends to export skilled-labor-intensive goods, and tends to import unskilled-labor-intensive goods.
Intra-industry trade
The traditional model of trade were set out by the model of David Ricardo and the Heckscher–Ohlin model, which tried to explain the occurrence of international trade. Both models used the idea of comparative advantage and an explanation of why countries trade. However, many economists have made the point of claiming that these models provide no explanation towards intra-industry trade as under their assumptions countries with identical factor endowments would not trade and produce goods domestically. Hence, as intra-industry trade has developed many economists have looked at other explanations.
Heckscher–Ohlin model
The Heckscher–Ohlin model (H–O model) is a general equilibrium mathematical model of international trade, developed by Eli Heckscher and Bertil Ohlin at the Stockholm School of Economics. It builds on David Ricardo's theory of comparative advantage by predicting patterns of commerce and production based on the factor endowments of a trading region. The model essentially says that countries export products that use their abundant and cheap factors of production, and import products that use the countries' scarce factors.
Taras Vintsiuk
Widely applied generative model for pattern recognition was firstly formulated and proposed by Taras Vintsiuk in 1967. This approach, commonly known as Dynamic Time Warping (DTW), is used not only in the theory of speech and visual pattern recognition, but also in text processing and non-linear process modeling in radio-physics and biology. Similar model, known as Hidden Markov Model (HMM), was originated in 1973 and is the most cited in the world. Both models are most productive in speech recognition systems and possess global leading positions.
Heckscher–Ohlin model
A common understanding exists that in the national level HOV model fits well. In fact, Davis and others found that HOV model fitted extremely well with the regional data of Japan. Even when the HOV formula fits well, it does not mean that Heckscher–Ohlin theory is valid. Indeed, Heckscher–Ohlin theory claims that the state of factor endowments of each country (or each region) determines the production of each country (respectively of each region) but Bernstein and Weinstein found that the factor endowments have little predictive power. The factor-endowments-driven model (FED model) has errors much greater than the HOV model.