Fred Campano and Dominick Salvatore
- Published in print:
- 2006
- Published Online:
- May 2006
- ISBN:
- 9780195300918
- eISBN:
- 9780199783441
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0195300912.001.0001
- Subject:
- Economics and Finance, Development, Growth, and Environmental
Intended as an introductory textbook for advanced undergraduates and first year graduate students, this book leads the reader from familiar basic micro- and macroeconomic concepts in the introduction ...
More
Intended as an introductory textbook for advanced undergraduates and first year graduate students, this book leads the reader from familiar basic micro- and macroeconomic concepts in the introduction to not so familiar concepts relating to income distribution in the subsequent chapters. The income concept and household sample surveys are examined first, followed by descriptive statistics techniques commonly used to present the survey results. The commonality found in the shape of the income density function leads to statistical modeling, parameter estimation, and goodness of fit tests. Alternative models are then introduced along with the related summary measures of income distribution, including the Gini coefficient. This is followed by a sequence of chapters that deal with normative issues such as inequality, poverty, and country comparisons. The remaining chapters cover an assortment of topics including: economic development and globalization and their impact on income distribution, redistribution of income, and integrating macroeconomic models with income distribution models.Less
Intended as an introductory textbook for advanced undergraduates and first year graduate students, this book leads the reader from familiar basic micro- and macroeconomic concepts in the introduction to not so familiar concepts relating to income distribution in the subsequent chapters. The income concept and household sample surveys are examined first, followed by descriptive statistics techniques commonly used to present the survey results. The commonality found in the shape of the income density function leads to statistical modeling, parameter estimation, and goodness of fit tests. Alternative models are then introduced along with the related summary measures of income distribution, including the Gini coefficient. This is followed by a sequence of chapters that deal with normative issues such as inequality, poverty, and country comparisons. The remaining chapters cover an assortment of topics including: economic development and globalization and their impact on income distribution, redistribution of income, and integrating macroeconomic models with income distribution models.
Franck Courchamp, Ludek Berec, and Joanna Gascoigne
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780198570301
- eISBN:
- 9780191717642
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198570301.001.0001
- Subject:
- Biology, Biodiversity / Conservation Biology
Allee effects are broadly defined as a decline in individual fitness at low population size or density, that can result in critical population thresholds below which populations crash to extinction. ...
More
Allee effects are broadly defined as a decline in individual fitness at low population size or density, that can result in critical population thresholds below which populations crash to extinction. As such, they are very relevant to many conservation programmes, where scientists and managers are often working with populations that have been reduced to low densities or small numbers. There are a variety of mechanisms that can create Allee effects, including mating systems, predation, environmental modification, and social interactions among others. The abrupt and unpredicted collapses of many exploited populations is just one illustration of the need to bring Allee effects to the forefront of conservation and management strategies. This book provides an overview of the topic, collating and integrating a widely dispersed literature from various fields: marine and terrestrial, plant and animal, theoretical and empirical, academic and applied. Less
Allee effects are broadly defined as a decline in individual fitness at low population size or density, that can result in critical population thresholds below which populations crash to extinction. As such, they are very relevant to many conservation programmes, where scientists and managers are often working with populations that have been reduced to low densities or small numbers. There are a variety of mechanisms that can create Allee effects, including mating systems, predation, environmental modification, and social interactions among others. The abrupt and unpredicted collapses of many exploited populations is just one illustration of the need to bring Allee effects to the forefront of conservation and management strategies. This book provides an overview of the topic, collating and integrating a widely dispersed literature from various fields: marine and terrestrial, plant and animal, theoretical and empirical, academic and applied.
Andrea Braides
- Published in print:
- 2002
- Published Online:
- September 2007
- ISBN:
- 9780198507840
- eISBN:
- 9780191709890
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198507840.003.0016
- Subject:
- Mathematics, Applied Mathematics
This chapter presents a self-contained account of the slicing method that allows the exhibition of a lower bound for high-dimensional problems through their one-dimensional sections. After computing ...
More
This chapter presents a self-contained account of the slicing method that allows the exhibition of a lower bound for high-dimensional problems through their one-dimensional sections. After computing a family of one-dimensional limit problems, an optimization is performed through an argument characterizing the supremum of a family of measures. The upper inequality is obtained by a density argument whenever recovery sequences have a one-dimensional form. This method can be applied to the high-dimensional gradient theory of phase transitions.Less
This chapter presents a self-contained account of the slicing method that allows the exhibition of a lower bound for high-dimensional problems through their one-dimensional sections. After computing a family of one-dimensional limit problems, an optimization is performed through an argument characterizing the supremum of a family of measures. The upper inequality is obtained by a density argument whenever recovery sequences have a one-dimensional form. This method can be applied to the high-dimensional gradient theory of phase transitions.
Helmut Hofmann
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780198504016
- eISBN:
- 9780191708480
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198504016.003.0020
- Subject:
- Physics, Nuclear and Plasma Physics
This chapter formulates the Hartree-Fock approximation with density matrices, and discusses the properties of the Hartree-Fock equations together with the energy functional for the ground state ...
More
This chapter formulates the Hartree-Fock approximation with density matrices, and discusses the properties of the Hartree-Fock equations together with the energy functional for the ground state energy. A generalization to finite thermal excitations is performed by applying the variational principle to the grand canonical ensemble. Finally, the equations for time-dependent Hartree-Fock (TDHF) are described both at zero and at finite temperature.Less
This chapter formulates the Hartree-Fock approximation with density matrices, and discusses the properties of the Hartree-Fock equations together with the energy functional for the ground state energy. A generalization to finite thermal excitations is performed by applying the variational principle to the grand canonical ensemble. Finally, the equations for time-dependent Hartree-Fock (TDHF) are described both at zero and at finite temperature.
Malcolm Cooper, Peter Mijnarends, Nobuhiro Shiotani, Nobuhiko Sakai, and Arun Bansil
- Published in print:
- 2004
- Published Online:
- September 2007
- ISBN:
- 9780198501688
- eISBN:
- 9780191718045
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198501688.001.0001
- Subject:
- Physics, Atomic, Laser, and Optical Physics
This book covers all aspects of the study of ground state electron density in condensed matter through Compton scattering of hard x-rays or gamma rays, i.e., photons with energies between 20 and 500 ...
More
This book covers all aspects of the study of ground state electron density in condensed matter through Compton scattering of hard x-rays or gamma rays, i.e., photons with energies between 20 and 500 keV. This inelastic scattering process yields information about the momentum distribution of the electrons: it is complementary to x-ray diffraction studies of the position space electron density. After a brief historical introduction, the scattering cross-section is fully elaborated and the approximations within which the experiments can be interpreted are spelled out. All the experimental methods associated with the study of the electron’s momentum density distribution are described and the interpretative techniques are detailed, including the two methods of reconstructing the three-dimensional distribution from the measurement sets. Particular emphasis is placed on the use of synchrotron radiation as the radiation source, especially the use of circularly polarized synchrotron radiation to study the spin-dependent distribution in ferro-magnets. The book concludes with a comparison between Compton scattering methods and a number of allied techniques.Less
This book covers all aspects of the study of ground state electron density in condensed matter through Compton scattering of hard x-rays or gamma rays, i.e., photons with energies between 20 and 500 keV. This inelastic scattering process yields information about the momentum distribution of the electrons: it is complementary to x-ray diffraction studies of the position space electron density. After a brief historical introduction, the scattering cross-section is fully elaborated and the approximations within which the experiments can be interpreted are spelled out. All the experimental methods associated with the study of the electron’s momentum density distribution are described and the interpretative techniques are detailed, including the two methods of reconstructing the three-dimensional distribution from the measurement sets. Particular emphasis is placed on the use of synchrotron radiation as the radiation source, especially the use of circularly polarized synchrotron radiation to study the spin-dependent distribution in ferro-magnets. The book concludes with a comparison between Compton scattering methods and a number of allied techniques.
John V. Kulvicki
- Published in print:
- 2006
- Published Online:
- September 2006
- ISBN:
- 9780199290758
- eISBN:
- 9780191604010
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/019929075X.003.0001
- Subject:
- Philosophy, Aesthetics
This chapter reviews Nelson Goodman’s proposals concerning depiction, identifies problems with them, and suggests how they can be overcome without appealing to a perceptual account of pictorial ...
More
This chapter reviews Nelson Goodman’s proposals concerning depiction, identifies problems with them, and suggests how they can be overcome without appealing to a perceptual account of pictorial representation. Goodman’s proposal is that all pictorial systems are relatively replete, syntactically dense, and semantically dense. This is problematic because repleteness is not as well-defined as it should be, and density requires that pictures be analog representations, while many seem to be digital. These conditions were never meant to be sufficient for a system to be pictorial, but the problem is that they seem to be unnecessary as well.Less
This chapter reviews Nelson Goodman’s proposals concerning depiction, identifies problems with them, and suggests how they can be overcome without appealing to a perceptual account of pictorial representation. Goodman’s proposal is that all pictorial systems are relatively replete, syntactically dense, and semantically dense. This is problematic because repleteness is not as well-defined as it should be, and density requires that pictures be analog representations, while many seem to be digital. These conditions were never meant to be sufficient for a system to be pictorial, but the problem is that they seem to be unnecessary as well.
Louis A. Girifalco
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780199228966
- eISBN:
- 9780191711183
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199228966.003.0019
- Subject:
- Physics, History of Physics
Gravity is responsible not only for the existence of stars and planets; it also creates the weirdest objects imaginable. A body with mass greater than 1.4 solar masses cannot remain a white dwarf and ...
More
Gravity is responsible not only for the existence of stars and planets; it also creates the weirdest objects imaginable. A body with mass greater than 1.4 solar masses cannot remain a white dwarf and will collapse into a neutron star. But if the mass is greater than about two and a half solar masses, the collapse will continue until it becomes a black hole. This is the strangest object in the universe. Its gravity is so strong that even light cannot get out of it. Anything near it is sucked in, crushed to a point, and approaches infinite density. The laws of physics as now known do not apply at the centre of a black hole and the very meaning of its existence is in doubt.Less
Gravity is responsible not only for the existence of stars and planets; it also creates the weirdest objects imaginable. A body with mass greater than 1.4 solar masses cannot remain a white dwarf and will collapse into a neutron star. But if the mass is greater than about two and a half solar masses, the collapse will continue until it becomes a black hole. This is the strangest object in the universe. Its gravity is so strong that even light cannot get out of it. Anything near it is sucked in, crushed to a point, and approaches infinite density. The laws of physics as now known do not apply at the centre of a black hole and the very meaning of its existence is in doubt.
Dennis Sherwood and Jon Cooper
- Published in print:
- 2010
- Published Online:
- January 2011
- ISBN:
- 9780199559046
- eISBN:
- 9780191595028
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199559046.001.0001
- Subject:
- Physics, Crystallography: Physics
This book presents a complete account of the theory of the diffraction of X-rays by crystals with particular reference to the processes of determining the structures of protein molecules. The book ...
More
This book presents a complete account of the theory of the diffraction of X-rays by crystals with particular reference to the processes of determining the structures of protein molecules. The book develops from first principles all relevant mathematics, diffraction, and wave theory. The practical aspects of sample preparation and X-ray data collection using both laboratory and synchrotron sources are covered along with data analysis at both the theoretical and practical levels. The important role played by the Patterson function in structure analysis by both molecular replacement and experimental phasing approaches is covered, as are methods for improving the resulting electron density map. The theoretical basis of methods used in refinement of protein crystal structures are then covered in depth along with the crucial task of defining the binding sites of ligands and drug molecules. The complementary roles of other diffraction methods which reveal further detail of great functional importance in a crystal structure are outlined.Less
This book presents a complete account of the theory of the diffraction of X-rays by crystals with particular reference to the processes of determining the structures of protein molecules. The book develops from first principles all relevant mathematics, diffraction, and wave theory. The practical aspects of sample preparation and X-ray data collection using both laboratory and synchrotron sources are covered along with data analysis at both the theoretical and practical levels. The important role played by the Patterson function in structure analysis by both molecular replacement and experimental phasing approaches is covered, as are methods for improving the resulting electron density map. The theoretical basis of methods used in refinement of protein crystal structures are then covered in depth along with the crucial task of defining the binding sites of ligands and drug molecules. The complementary roles of other diffraction methods which reveal further detail of great functional importance in a crystal structure are outlined.
Gary A. Glatzmaier
- Published in print:
- 2013
- Published Online:
- October 2017
- ISBN:
- 9780691141725
- eISBN:
- 9781400848904
- Item type:
- book
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691141725.001.0001
- Subject:
- Physics, Particle Physics / Astrophysics / Cosmology
This book provides readers with the skills they need to write computer codes that simulate convection, internal gravity waves, and magnetic field generation in the interiors and atmospheres of ...
More
This book provides readers with the skills they need to write computer codes that simulate convection, internal gravity waves, and magnetic field generation in the interiors and atmospheres of rotating planets and stars. Using a teaching method perfected in the classroom, the book begins by offering a step-by-step guide on how to design codes for simulating nonlinear time-dependent thermal convection in a 2D box using Fourier expansions in the horizontal direction and finite differences in the vertical direction. It then describes how to implement more efficient a nd accurate numerical methods and more realistic geometries in two and three dimensions. The third part of the book demonstrates how to incorporate more sophisticated physics, including the effects of magnetic field, density stratification, and rotation. The book features numerous exercises throughout, and is an ideal textbook for students and an essential resource for researchers. It explains how to create codes that simulate the internal dynamics of planets and stars, and builds on basic concepts and simple methods. The book shows how to improve the efficiency and accuracy of the numerical methods. It considers more relevant geometries and boundary conditions.Less
This book provides readers with the skills they need to write computer codes that simulate convection, internal gravity waves, and magnetic field generation in the interiors and atmospheres of rotating planets and stars. Using a teaching method perfected in the classroom, the book begins by offering a step-by-step guide on how to design codes for simulating nonlinear time-dependent thermal convection in a 2D box using Fourier expansions in the horizontal direction and finite differences in the vertical direction. It then describes how to implement more efficient a nd accurate numerical methods and more realistic geometries in two and three dimensions. The third part of the book demonstrates how to incorporate more sophisticated physics, including the effects of magnetic field, density stratification, and rotation. The book features numerous exercises throughout, and is an ideal textbook for students and an essential resource for researchers. It explains how to create codes that simulate the internal dynamics of planets and stars, and builds on basic concepts and simple methods. The book shows how to improve the efficiency and accuracy of the numerical methods. It considers more relevant geometries and boundary conditions.
Stephen Rand
- Published in print:
- 2010
- Published Online:
- September 2010
- ISBN:
- 9780199574872
- eISBN:
- 9780191722219
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199574872.001.0001
- Subject:
- Physics, Atomic, Laser, and Optical Physics
This book attempts to bridge the enormous gap between introductory quantum mechanics and the research front of modern optics and scientific fields that make use of light in one step. Hence, while it ...
More
This book attempts to bridge the enormous gap between introductory quantum mechanics and the research front of modern optics and scientific fields that make use of light in one step. Hence, while it is suitable as a reference for the specialist in quantum optics, it also targets the nonspecialists from other disciplines who need to understand light and its uses in research. With a unique approach it introduces a single analytic tool, namely the density matrix, to analyze complex optical phenomena encountered in traditional as well as cross‐disciplinary research. It moves swiftly in a tight sequence from elementary to sophisticated topics in quantum optics, including laser tweezers, laser cooling, coherent population transfer, optical magnetism, electromagnetically induced transparency (EIT), squeezed light, and cavity quantum electrodynamics (QED). A systematic approach is used that starts with the simplest systems – stationary two‐level atoms – then introduces atomic motion, adds more energy levels, and moves on to discuss first‐, second‐, and third‐order coherence effects that are the basis for analyzing new optical phenomena in incompletely characterized systems. Unconventional examples and original problems are used to engage even seasoned researchers in exploring a mathematical methodology with which they can tackle virtually any new problem involving light. An extensive bibliography makes connections with mathematical techniques and subject areas which can extend the benefit of each section to guide readers further. The steady progression from “simple” to “elaborate” makes the book accessible not only to students from traditional subject areas that make use of light (physics, chemistry, electrical engineering, and materials science), but also to researchers from the “hyphenated” subjects of modern science and engineering: the biophysicists using mechanical effects of light, photochemists developing coherent control for rare species detection, biomedical engineers imaging through scattering media, electromechanical engineers working on molecular design of materials for electronics and space, electrical and computer engineers developing schemes for quantum computation, cryptography, frequency references, and so on. To try to identify techniques and ideas that are universal enough to be applied across the bewildering landscape of research on intersecting boundaries of emerging modern disciplines is a great challenge of out time. “Lectures on Light” offers selected insights on quantum dynamics and quantum theory of light for exactly this purpose.Less
This book attempts to bridge the enormous gap between introductory quantum mechanics and the research front of modern optics and scientific fields that make use of light in one step. Hence, while it is suitable as a reference for the specialist in quantum optics, it also targets the nonspecialists from other disciplines who need to understand light and its uses in research. With a unique approach it introduces a single analytic tool, namely the density matrix, to analyze complex optical phenomena encountered in traditional as well as cross‐disciplinary research. It moves swiftly in a tight sequence from elementary to sophisticated topics in quantum optics, including laser tweezers, laser cooling, coherent population transfer, optical magnetism, electromagnetically induced transparency (EIT), squeezed light, and cavity quantum electrodynamics (QED). A systematic approach is used that starts with the simplest systems – stationary two‐level atoms – then introduces atomic motion, adds more energy levels, and moves on to discuss first‐, second‐, and third‐order coherence effects that are the basis for analyzing new optical phenomena in incompletely characterized systems. Unconventional examples and original problems are used to engage even seasoned researchers in exploring a mathematical methodology with which they can tackle virtually any new problem involving light. An extensive bibliography makes connections with mathematical techniques and subject areas which can extend the benefit of each section to guide readers further. The steady progression from “simple” to “elaborate” makes the book accessible not only to students from traditional subject areas that make use of light (physics, chemistry, electrical engineering, and materials science), but also to researchers from the “hyphenated” subjects of modern science and engineering: the biophysicists using mechanical effects of light, photochemists developing coherent control for rare species detection, biomedical engineers imaging through scattering media, electromechanical engineers working on molecular design of materials for electronics and space, electrical and computer engineers developing schemes for quantum computation, cryptography, frequency references, and so on. To try to identify techniques and ideas that are universal enough to be applied across the bewildering landscape of research on intersecting boundaries of emerging modern disciplines is a great challenge of out time. “Lectures on Light” offers selected insights on quantum dynamics and quantum theory of light for exactly this purpose.
Chris Bramall
- Published in print:
- 2006
- Published Online:
- January 2007
- ISBN:
- 9780199275939
- eISBN:
- 9780191706073
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199275939.003.0007
- Subject:
- Economics and Finance, South and East Asia
The evidence on the determinants of growth for China’s counties in the post-1978 era points to the clear causal role of initial conditions. Proximity to large urban centres, the dependency rate, and ...
More
The evidence on the determinants of growth for China’s counties in the post-1978 era points to the clear causal role of initial conditions. Proximity to large urban centres, the dependency rate, and initial GDP per head all appeared to have exerted a powerful impact, much more so than population density, literacy, grain yields, or proximity to a provincial capital. Most importantly, the hypothesis advanced in this book: that inherited industrial skills helped promote growth, is supported in both a statistical and a substantive sense. Whatever the impact of policy change, it should not be allowed to overshadow the contribution of both geography and history. Although location mattered, so too did prior learning — and in a much more positive sense than much of the path dependency literature allows.Less
The evidence on the determinants of growth for China’s counties in the post-1978 era points to the clear causal role of initial conditions. Proximity to large urban centres, the dependency rate, and initial GDP per head all appeared to have exerted a powerful impact, much more so than population density, literacy, grain yields, or proximity to a provincial capital. Most importantly, the hypothesis advanced in this book: that inherited industrial skills helped promote growth, is supported in both a statistical and a substantive sense. Whatever the impact of policy change, it should not be allowed to overshadow the contribution of both geography and history. Although location mattered, so too did prior learning — and in a much more positive sense than much of the path dependency literature allows.
Marc Mézard and Andrea Montanari
- Published in print:
- 2009
- Published Online:
- September 2009
- ISBN:
- 9780198570837
- eISBN:
- 9780191718755
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198570837.001.0001
- Subject:
- Physics, Theoretical, Computational, and Statistical Physics
This book presents a unified approach to a rich and rapidly evolving research domain at the interface between statistical physics, theoretical computer science/discrete mathematics, and ...
More
This book presents a unified approach to a rich and rapidly evolving research domain at the interface between statistical physics, theoretical computer science/discrete mathematics, and coding/information theory. The topics which have been selected, including spin glasses, error correcting codes, satisfiability, are central to each field. The approach focuses on the limit of large random instances, adopting a common formulation in terms of graphical models. It presents message passing algorithms like belief propagation and survey propagation, and their use in decoding and constraint satisfaction solving. It also explains analysis techniques like density evolution and the cavity method, and uses them to derive phase diagrams and study phase transitions.Less
This book presents a unified approach to a rich and rapidly evolving research domain at the interface between statistical physics, theoretical computer science/discrete mathematics, and coding/information theory. The topics which have been selected, including spin glasses, error correcting codes, satisfiability, are central to each field. The approach focuses on the limit of large random instances, adopting a common formulation in terms of graphical models. It presents message passing algorithms like belief propagation and survey propagation, and their use in decoding and constraint satisfaction solving. It also explains analysis techniques like density evolution and the cavity method, and uses them to derive phase diagrams and study phase transitions.
Fred Campano and Dominick Salvatore
- Published in print:
- 2006
- Published Online:
- May 2006
- ISBN:
- 9780195300918
- eISBN:
- 9780199783441
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/0195300912.003.0003
- Subject:
- Economics and Finance, Development, Growth, and Environmental
This chapter starts with Pareto’s law and the observation by other economists of the consistency of right-hand skewness in income distributions in both developing and developed countries. This leads ...
More
This chapter starts with Pareto’s law and the observation by other economists of the consistency of right-hand skewness in income distributions in both developing and developed countries. This leads to the modeling of income distribution with probability density functions. This is illustrated using the lognormal model.Less
This chapter starts with Pareto’s law and the observation by other economists of the consistency of right-hand skewness in income distributions in both developing and developed countries. This leads to the modeling of income distribution with probability density functions. This is illustrated using the lognormal model.
Željko Ivezi, Andrew J. Connolly, Jacob T. VanderPlas, Alexander Gray, Željko Ivezi, Andrew J. Connolly, Jacob T. VanderPlas, and Alexander Gray
- Published in print:
- 2014
- Published Online:
- October 2017
- ISBN:
- 9780691151687
- eISBN:
- 9781400848911
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691151687.003.0006
- Subject:
- Physics, Particle Physics / Astrophysics / Cosmology
Inferring the probability density function (pdf) from a sample of data is known as density estimation. The same methodology is often called data smoothing. Density estimation in the one-dimensional ...
More
Inferring the probability density function (pdf) from a sample of data is known as density estimation. The same methodology is often called data smoothing. Density estimation in the one-dimensional case has been discussed in the previous chapters. This chapter extends it to multidimensional cases. Density estimation is one of the most critical components of extracting knowledge from data. For example, given a pdf estimated from point data, we can generate simulated distributions of data and compare them against observations. If we can identify regions of low probability within the pdf, we have a mechanism for the detection of unusual or anomalous sources. If our point data can be separated into subsamples using provided class labels, we can estimate the pdf for each subsample and use the resulting set of pdfs to classify new points: the probability that a new point belongs to each subsample/class is proportional to the pdf of each class evaluated at the position of the point.Less
Inferring the probability density function (pdf) from a sample of data is known as density estimation. The same methodology is often called data smoothing. Density estimation in the one-dimensional case has been discussed in the previous chapters. This chapter extends it to multidimensional cases. Density estimation is one of the most critical components of extracting knowledge from data. For example, given a pdf estimated from point data, we can generate simulated distributions of data and compare them against observations. If we can identify regions of low probability within the pdf, we have a mechanism for the detection of unusual or anomalous sources. If our point data can be separated into subsamples using provided class labels, we can estimate the pdf for each subsample and use the resulting set of pdfs to classify new points: the probability that a new point belongs to each subsample/class is proportional to the pdf of each class evaluated at the position of the point.
Nikolaus Beck
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780199231423
- eISBN:
- 9780191710865
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199231423.003.0010
- Subject:
- Business and Management, Political Economy
This chapter shows that organizational ecology is much more sociological and less biological than many critics of organizational ecology think. It argues that organizational ecology and its theory of ...
More
This chapter shows that organizational ecology is much more sociological and less biological than many critics of organizational ecology think. It argues that organizational ecology and its theory of competition rests heavily on the seminal work of Emile Durkheim on the division of labour, and on the thoughts of Amos Hawley on human ecology. It suggests that the expressions used by the agents of organizational ecology are ‘Darwinian’ but that the theoretical argumentation is ‘Durkheimian’. The chapter highlights the theoretical foundations of organizational ecology and emphasizes that competition — and not the biological aspects of evolution — forms the core of the organizational ecology theory. The most the most important sub-concepts of organizational ecology that deal with competition and market formation are also discussed: density dependence and resource partitioning. The first concept deals with the impact of the number of competitors on the survival and founding chances of organizations. The latter is concerned with the influence of market concentration on the vital rates of specialist and generalist organizations.Less
This chapter shows that organizational ecology is much more sociological and less biological than many critics of organizational ecology think. It argues that organizational ecology and its theory of competition rests heavily on the seminal work of Emile Durkheim on the division of labour, and on the thoughts of Amos Hawley on human ecology. It suggests that the expressions used by the agents of organizational ecology are ‘Darwinian’ but that the theoretical argumentation is ‘Durkheimian’. The chapter highlights the theoretical foundations of organizational ecology and emphasizes that competition — and not the biological aspects of evolution — forms the core of the organizational ecology theory. The most the most important sub-concepts of organizational ecology that deal with competition and market formation are also discussed: density dependence and resource partitioning. The first concept deals with the impact of the number of competitors on the survival and founding chances of organizations. The latter is concerned with the influence of market concentration on the vital rates of specialist and generalist organizations.
Filippo Carlo Wezel, Christophe Boone, and Arjen van Witteloostuijn
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780199231423
- eISBN:
- 9780191710865
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199231423.003.0011
- Subject:
- Business and Management, Political Economy
This chapter has two main goals: (a) to model some of the variety of evolutionary paths of organizational populations empirically observed and (b) elaborate on a model refinement that captures the ...
More
This chapter has two main goals: (a) to model some of the variety of evolutionary paths of organizational populations empirically observed and (b) elaborate on a model refinement that captures the existence of legitimation and competition spillovers across national populations. In doing so, it contributes to an emerging branch of organizational ecology concerned with evolutionary processes taking place at the international level. A model is proposed that points to cross-country differences in timing of entry and development as key drivers of the country-specific processes of legitimation and competition. It distinguishes pioneer from follower countries, and uses this distinction to advance how observable patterns of population evolution — that is, density growth and decline — may be related to and sustained by spillover effects across countries. The proposed model is largely inspired by that literature in biology, in which the form and the strength of density-dependent evolution are modelled.Less
This chapter has two main goals: (a) to model some of the variety of evolutionary paths of organizational populations empirically observed and (b) elaborate on a model refinement that captures the existence of legitimation and competition spillovers across national populations. In doing so, it contributes to an emerging branch of organizational ecology concerned with evolutionary processes taking place at the international level. A model is proposed that points to cross-country differences in timing of entry and development as key drivers of the country-specific processes of legitimation and competition. It distinguishes pioneer from follower countries, and uses this distinction to advance how observable patterns of population evolution — that is, density growth and decline — may be related to and sustained by spillover effects across countries. The proposed model is largely inspired by that literature in biology, in which the form and the strength of density-dependent evolution are modelled.
Franck Courchamp, Luděk Berec, and Joanna Gascoigne
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780198570301
- eISBN:
- 9780191717642
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198570301.003.0002
- Subject:
- Biology, Biodiversity / Conservation Biology
This chapter describes the mechanisms by which an Allee effect can arise. For each mechanism, the chapter discusses how it works in theory, and then presents current evidence for, and examples of, ...
More
This chapter describes the mechanisms by which an Allee effect can arise. For each mechanism, the chapter discusses how it works in theory, and then presents current evidence for, and examples of, the mechanisms in practice. It begins with reproductive mechanisms, including fertilization efficiency in broadcast spawners, pollen limitation, mate finding, sperm limitation, reproductive facilitation by conspecifics, and female choice. It then moves on to mechanisms related to survival: environmental conditioning and particularly predation, both via the dilution effect and via group ‘behaviour’, such as flocking, coloniality, and group vigilence. Finally, the chapter discusses Allee effects in social and cooperative species, where group size is important for both reproduction and survival.Less
This chapter describes the mechanisms by which an Allee effect can arise. For each mechanism, the chapter discusses how it works in theory, and then presents current evidence for, and examples of, the mechanisms in practice. It begins with reproductive mechanisms, including fertilization efficiency in broadcast spawners, pollen limitation, mate finding, sperm limitation, reproductive facilitation by conspecifics, and female choice. It then moves on to mechanisms related to survival: environmental conditioning and particularly predation, both via the dilution effect and via group ‘behaviour’, such as flocking, coloniality, and group vigilence. Finally, the chapter discusses Allee effects in social and cooperative species, where group size is important for both reproduction and survival.
Peter Main
- Published in print:
- 2009
- Published Online:
- September 2009
- ISBN:
- 9780199219469
- eISBN:
- 9780191722516
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199219469.003.0011
- Subject:
- Physics, Crystallography: Physics
Maximum entropy methods are used in crystallography for estimating reflection phases among other applications. This chapter explains the basic concepts behind maximum entropy, including entropy ...
More
Maximum entropy methods are used in crystallography for estimating reflection phases among other applications. This chapter explains the basic concepts behind maximum entropy, including entropy itself and its relationship to probability and information. They are illustrated by a simple non-scientific example of estimating missing information based on reasonable assumptions.Less
Maximum entropy methods are used in crystallography for estimating reflection phases among other applications. This chapter explains the basic concepts behind maximum entropy, including entropy itself and its relationship to probability and information. They are illustrated by a simple non-scientific example of estimating missing information based on reasonable assumptions.
Mike Finnis
- Published in print:
- 2003
- Published Online:
- January 2010
- ISBN:
- 9780198509776
- eISBN:
- 9780191709180
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198509776.001.0001
- Subject:
- Physics, Atomic, Laser, and Optical Physics
There is a continuing growth of interest in the computer simulation of materials at the atomic scale, using a variety of academic and commercial computer programs. In all such programs there is some ...
More
There is a continuing growth of interest in the computer simulation of materials at the atomic scale, using a variety of academic and commercial computer programs. In all such programs there is some physical model of the interatomic forces. For a student or researcher, the basis of such models is often shrouded in mystery. It is usually unclear how well founded they are, since it is hard to find a discussion of the physical assumptions that have been made in their construction. The lack of clear understanding of the scope and limitations of a given model may lead to its innocent misuse, resulting either in unfair criticism of the model or in the dissemination of nonsensical results. In this book, models of interatomic forces are derived from a common physical basis, namely the density functional theory. The book includes the detailed derivation of pairwise potentials in simple metals, tight-binding models from the simplest to the most sophisticated (self-consistent) kind, and ionic models. It provides a critical appreciation of the broad range of models in current use, and provides the tools for understanding other variants that are described in the literature. Some of the material is new, and some pointers are given to possible future avenues of model development.Less
There is a continuing growth of interest in the computer simulation of materials at the atomic scale, using a variety of academic and commercial computer programs. In all such programs there is some physical model of the interatomic forces. For a student or researcher, the basis of such models is often shrouded in mystery. It is usually unclear how well founded they are, since it is hard to find a discussion of the physical assumptions that have been made in their construction. The lack of clear understanding of the scope and limitations of a given model may lead to its innocent misuse, resulting either in unfair criticism of the model or in the dissemination of nonsensical results. In this book, models of interatomic forces are derived from a common physical basis, namely the density functional theory. The book includes the detailed derivation of pairwise potentials in simple metals, tight-binding models from the simplest to the most sophisticated (self-consistent) kind, and ionic models. It provides a critical appreciation of the broad range of models in current use, and provides the tools for understanding other variants that are described in the literature. Some of the material is new, and some pointers are given to possible future avenues of model development.
Jan‐Erik Lane, David McKay, and Kenneth Newton
- Published in print:
- 1996
- Published Online:
- January 2005
- ISBN:
- 9780198280538
- eISBN:
- 9780191601934
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/019828053X.003.0002
- Subject:
- Political Science, Reference
This section presents population data on OECD countries. It features tables on mid-year estimates, population growth, population density, age structure, birth rate, life expectancy, infant mortality ...
More
This section presents population data on OECD countries. It features tables on mid-year estimates, population growth, population density, age structure, birth rate, life expectancy, infant mortality rates, and urban concentration.Less
This section presents population data on OECD countries. It features tables on mid-year estimates, population growth, population density, age structure, birth rate, life expectancy, infant mortality rates, and urban concentration.
