Ernest H. Williams
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780195179293
- eISBN:
- 9780199790470
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195179293.003.0014
- Subject:
- Biology, Natural History and Field Guides
This final chapter presents key observations over broad spatial and temporal scales. The first three are readily observable, at least in the right geographic areas, but the last two — species and ...
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This final chapter presents key observations over broad spatial and temporal scales. The first three are readily observable, at least in the right geographic areas, but the last two — species and area, and latitudinal gradient — are the two broadest patterns in the distribution of life on earth. Though not immediately observable, they help one understand nature a little better, which is the overall goal of this book.Less
This final chapter presents key observations over broad spatial and temporal scales. The first three are readily observable, at least in the right geographic areas, but the last two — species and area, and latitudinal gradient — are the two broadest patterns in the distribution of life on earth. Though not immediately observable, they help one understand nature a little better, which is the overall goal of this book.
Michael Marmot and Richard Wilkinson (eds)
- Published in print:
- 2005
- Published Online:
- September 2009
- ISBN:
- 9780198565895
- eISBN:
- 9780191723988
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198565895.001.0001
- Subject:
- Public Health and Epidemiology, Public Health, Epidemiology
The health of populations is related to features of society and its social and economic organization. This crucial fact provides the basis for effective policy-making for improving population health. ...
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The health of populations is related to features of society and its social and economic organization. This crucial fact provides the basis for effective policy-making for improving population health. While there is, understandably, much concern regarding the appropriate provision and financing of health services as well as ensuring that the nature of the services provided is based on the best evidence of effectiveness, health is a matter that goes beyond the provision of health services. Policies pursued by many branches of government and by the private sector, both nationally and locally, exert a powerful influence on health — and this book shows the direction in which we should be going. Just as decisions about health services should be based on the best evidence available, so should policies related to the social determinants of health. The social determinants covered by the book include the impact of early life; the life course, the social gradient, and health; labour market disadvantage, unemployment, non-employment, and job insecurity; the psychosocial environment at work; transport; social support and social cohesion; the politics of food; poverty, social exclusion, and minorities; social patterning of individual behaviours; social determinants of ethnic/ racial inequalities; social determinants of health in older age; neighbourhoods, housing, and health; sexual behaviour and sexual health; and social vulnerability.Less
The health of populations is related to features of society and its social and economic organization. This crucial fact provides the basis for effective policy-making for improving population health. While there is, understandably, much concern regarding the appropriate provision and financing of health services as well as ensuring that the nature of the services provided is based on the best evidence of effectiveness, health is a matter that goes beyond the provision of health services. Policies pursued by many branches of government and by the private sector, both nationally and locally, exert a powerful influence on health — and this book shows the direction in which we should be going. Just as decisions about health services should be based on the best evidence available, so should policies related to the social determinants of health. The social determinants covered by the book include the impact of early life; the life course, the social gradient, and health; labour market disadvantage, unemployment, non-employment, and job insecurity; the psychosocial environment at work; transport; social support and social cohesion; the politics of food; poverty, social exclusion, and minorities; social patterning of individual behaviours; social determinants of ethnic/ racial inequalities; social determinants of health in older age; neighbourhoods, housing, and health; sexual behaviour and sexual health; and social vulnerability.
Stephen Gorard
- Published in print:
- 2018
- Published Online:
- May 2019
- ISBN:
- 9781447342144
- eISBN:
- 9781447342212
- Item type:
- book
- Publisher:
- Policy Press
- DOI:
- 10.1332/policypress/9781447342144.001.0001
- Subject:
- Education, Educational Policy and Politics
What has been done to achieve fairer and more efficient education systems, and what more can be done in the future? This book provides a comprehensive examination of crucial policy areas for ...
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What has been done to achieve fairer and more efficient education systems, and what more can be done in the future? This book provides a comprehensive examination of crucial policy areas for education, such as differential outcomes, the poverty gradient, and the allocation of resources to education, to identify likely causes of educational disadvantage among students and lifelong learners. This analysis is supported by 20 years of extensive research, based in the home countries of the UK and on work in all EU 28 countries, USA, Pakistan, and Japan. The book brings invaluable insights into the underlying problems within education policy, and proposes practical solutions for a brighter future.Less
What has been done to achieve fairer and more efficient education systems, and what more can be done in the future? This book provides a comprehensive examination of crucial policy areas for education, such as differential outcomes, the poverty gradient, and the allocation of resources to education, to identify likely causes of educational disadvantage among students and lifelong learners. This analysis is supported by 20 years of extensive research, based in the home countries of the UK and on work in all EU 28 countries, USA, Pakistan, and Japan. The book brings invaluable insights into the underlying problems within education policy, and proposes practical solutions for a brighter future.
John R. B. Lighton
- Published in print:
- 2008
- Published Online:
- September 2008
- ISBN:
- 9780195310610
- eISBN:
- 9780199871414
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195310610.003.0006
- Subject:
- Biology, Animal Biology, Biotechnology
This chapter describes calorimetry or the direct measurement of heat production, a technique first used by Lavoisier and Paulze for measuring metabolic rates. Bomb calorimetry — a technique for ...
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This chapter describes calorimetry or the direct measurement of heat production, a technique first used by Lavoisier and Paulze for measuring metabolic rates. Bomb calorimetry — a technique for measuring the energy content of foods and other materials — is also described. The two most common applications of direct calorimetry — gradient and differential calorimetry — are analyzed. Methods for combining direct calorimetry with indirect calorimetry (or respirometry) and the compensating calculations that are required, are presented, together with a brief description of a basic direct calorimeter for small mammals that can be made from inexpensive and commonly available materials.Less
This chapter describes calorimetry or the direct measurement of heat production, a technique first used by Lavoisier and Paulze for measuring metabolic rates. Bomb calorimetry — a technique for measuring the energy content of foods and other materials — is also described. The two most common applications of direct calorimetry — gradient and differential calorimetry — are analyzed. Methods for combining direct calorimetry with indirect calorimetry (or respirometry) and the compensating calculations that are required, are presented, together with a brief description of a basic direct calorimeter for small mammals that can be made from inexpensive and commonly available materials.
David N. Thomas, G.E. (Tony) Fogg, Peter Convey, Christian H. Fritsen, Josep-Maria Gili, Rolf Gradinger, Johanna Laybourn-Parry, Keith Reid, and David W.H. Walton
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780199298112
- eISBN:
- 9780191711640
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199298112.003.0006
- Subject:
- Biology, Ecology
This chapter discusses the ecology of open oceans in polar regions. Topics covered include gradients in waters, the plankton, the physiological ecology of polar phytoplankton, the zooplankton, squid, ...
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This chapter discusses the ecology of open oceans in polar regions. Topics covered include gradients in waters, the plankton, the physiological ecology of polar phytoplankton, the zooplankton, squid, fish, and polar marine pelagic systems.Less
This chapter discusses the ecology of open oceans in polar regions. Topics covered include gradients in waters, the plankton, the physiological ecology of polar phytoplankton, the zooplankton, squid, fish, and polar marine pelagic systems.
Kate E. Pickett and Richard G. Wilkinson
- Published in print:
- 2012
- Published Online:
- January 2013
- ISBN:
- 9780197264980
- eISBN:
- 9780191754135
- Item type:
- chapter
- Publisher:
- British Academy
- DOI:
- 10.5871/bacad/9780197264980.003.0010
- Subject:
- Sociology, Health, Illness, and Medicine
Almost all health and social problems that have social gradients (more common further down the social ladder) are very much more common in societies with bigger income differences between rich and ...
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Almost all health and social problems that have social gradients (more common further down the social ladder) are very much more common in societies with bigger income differences between rich and poor. Obesity is part of a very general picture to do with class, status and inequality that affects longevity, violence, mental health, teenage births, drug abuse and child well-being, among other outcomes. The causal pathways through which obesity might be affected by inequality are discussed in this chapter.Less
Almost all health and social problems that have social gradients (more common further down the social ladder) are very much more common in societies with bigger income differences between rich and poor. Obesity is part of a very general picture to do with class, status and inequality that affects longevity, violence, mental health, teenage births, drug abuse and child well-being, among other outcomes. The causal pathways through which obesity might be affected by inequality are discussed in this chapter.
Ruth Bell, Amina Aitsi-Selmi, and Michael Marmot
- Published in print:
- 2012
- Published Online:
- January 2013
- ISBN:
- 9780197264980
- eISBN:
- 9780191754135
- Item type:
- chapter
- Publisher:
- British Academy
- DOI:
- 10.5871/bacad/9780197264980.003.0006
- Subject:
- Sociology, Health, Illness, and Medicine
The distribution of obesity in developed countries follows a social gradient. In developing countries, a similar pattern is emerging as national per capita income rises. The epidemiological evidence ...
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The distribution of obesity in developed countries follows a social gradient. In developing countries, a similar pattern is emerging as national per capita income rises. The epidemiological evidence runs counter to the popular opinion that being overweight and obesity are matters solely of individual lifestyle choices or genetics. Both are important, but in themselves do not explain the social gradient in being overweight and obesity, to understand which, one needs to look at wider social influences. Evidence from studies including the Whitehall Study of British civil servants indicates that psychosocial factors, including stress, as well as material factors associated with position in the social hierarchy, contribute to the distribution of being overweight and obesity, particularly central adiposity, in the population.Less
The distribution of obesity in developed countries follows a social gradient. In developing countries, a similar pattern is emerging as national per capita income rises. The epidemiological evidence runs counter to the popular opinion that being overweight and obesity are matters solely of individual lifestyle choices or genetics. Both are important, but in themselves do not explain the social gradient in being overweight and obesity, to understand which, one needs to look at wider social influences. Evidence from studies including the Whitehall Study of British civil servants indicates that psychosocial factors, including stress, as well as material factors associated with position in the social hierarchy, contribute to the distribution of being overweight and obesity, particularly central adiposity, in the population.
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/9780198507840.003.0007
- Subject:
- Mathematics, Applied Mathematics
Phase transitions with sharp interfaces are interpreted as segmentation problems, and are approximated with perturbations of non-convex energies (gradient theory of phase transitions). The ...
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Phase transitions with sharp interfaces are interpreted as segmentation problems, and are approximated with perturbations of non-convex energies (gradient theory of phase transitions). The Modica-Mortola theorem is proved, with different formulas characterizing the segmentation energy (optimal-profile problems).Less
Phase transitions with sharp interfaces are interpreted as segmentation problems, and are approximated with perturbations of non-convex energies (gradient theory of phase transitions). The Modica-Mortola theorem is proved, with different formulas characterizing the segmentation energy (optimal-profile problems).
Moody T. Chu and Gene H. Golub
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780198566649
- eISBN:
- 9780191718021
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198566649.003.0007
- Subject:
- Mathematics, Applied Mathematics
This chapter shows that the problems of computing least squares approximations for various types of real and symmetric matrices subject to spectral constraints share a common structure. A general ...
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This chapter shows that the problems of computing least squares approximations for various types of real and symmetric matrices subject to spectral constraints share a common structure. A general framework by using the projected gradient method is described. A broad range of applications, including the Toeplitz inverse eigenvalue problem, the simultaneous reduction problem, and the nearest normal matrix approximation, are discussed.Less
This chapter shows that the problems of computing least squares approximations for various types of real and symmetric matrices subject to spectral constraints share a common structure. A general framework by using the projected gradient method is described. A broad range of applications, including the Toeplitz inverse eigenvalue problem, the simultaneous reduction problem, and the nearest normal matrix approximation, are discussed.
Ernest H. Williams
- Published in print:
- 2005
- Published Online:
- September 2007
- ISBN:
- 9780195179293
- eISBN:
- 9780199790470
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195179293.003.0008
- Subject:
- Biology, Natural History and Field Guides
This chapter describes the responses of trees to elevational gradients and the characteristics of plants (and one or two animals) that must cope with cold climates on the tops of mountains. The ...
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This chapter describes the responses of trees to elevational gradients and the characteristics of plants (and one or two animals) that must cope with cold climates on the tops of mountains. The higher the mountain, the stronger the environmental differences across the elevational gradient, and the more severe the challenges of life on top. These descriptions focus particularly on what one can see in the Rocky Mountains of the western states and the northeastern mountains of New York and New England.Less
This chapter describes the responses of trees to elevational gradients and the characteristics of plants (and one or two animals) that must cope with cold climates on the tops of mountains. The higher the mountain, the stronger the environmental differences across the elevational gradient, and the more severe the challenges of life on top. These descriptions focus particularly on what one can see in the Rocky Mountains of the western states and the northeastern mountains of New York and New England.
Thomas J. Stohlgren
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195172331
- eISBN:
- 9780199790395
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195172331.003.0001
- Subject:
- Biology, Plant Sciences and Forestry
This chapter reviews why standard methods for plant diversity studies have been slow to develop. It provides specific examples why plant diversity studies are inherently difficult due to issues of ...
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This chapter reviews why standard methods for plant diversity studies have been slow to develop. It provides specific examples why plant diversity studies are inherently difficult due to issues of taxonomy, phonology, and species rarity. In addition, it shows that designing plant diversity studies also is hampered by plant-to-plant neighborhood scale variability, landscape-to-regional scale variability, and long-term changes in plant diversity brought about by immigration, particularly plant species invasions from other countries.Less
This chapter reviews why standard methods for plant diversity studies have been slow to develop. It provides specific examples why plant diversity studies are inherently difficult due to issues of taxonomy, phonology, and species rarity. In addition, it shows that designing plant diversity studies also is hampered by plant-to-plant neighborhood scale variability, landscape-to-regional scale variability, and long-term changes in plant diversity brought about by immigration, particularly plant species invasions from other countries.
Thomas J. Stohlgren
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195172331
- eISBN:
- 9780199790395
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195172331.003.0005
- Subject:
- Biology, Plant Sciences and Forestry
This chapter reveals that sampling plant diversity at multiple spatial scales may allow for a deeper understanding of relationships between species distributions and composition shifts relative to ...
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This chapter reveals that sampling plant diversity at multiple spatial scales may allow for a deeper understanding of relationships between species distributions and composition shifts relative to changing environmental gradients. Like single-scale techniques, different multi-scale techniques have various strengths and weaknesses, and some may be better suited than others for particular study goals and objectives. No single design will be the “end all, be all” for plant diversity sampling. All designs have advantages and disadvantages that must be carefully evaluated. An experimental approach is almost always warranted. Several examples provide a glimpse of the profound potential of multi-scale sampling for plant diversity.Less
This chapter reveals that sampling plant diversity at multiple spatial scales may allow for a deeper understanding of relationships between species distributions and composition shifts relative to changing environmental gradients. Like single-scale techniques, different multi-scale techniques have various strengths and weaknesses, and some may be better suited than others for particular study goals and objectives. No single design will be the “end all, be all” for plant diversity sampling. All designs have advantages and disadvantages that must be carefully evaluated. An experimental approach is almost always warranted. Several examples provide a glimpse of the profound potential of multi-scale sampling for plant diversity.
Thomas S. Bianchi and Elizabeth A. Canuel
- Published in print:
- 2011
- Published Online:
- October 2017
- ISBN:
- 9780691134147
- eISBN:
- 9781400839100
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691134147.003.0002
- Subject:
- Biology, Ecology
This chapter provides a brief historical account of the success and limitations of using chemical biomarkers in aquatic ecosystems. It also introduces the general concepts of chemical biomarkers as ...
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This chapter provides a brief historical account of the success and limitations of using chemical biomarkers in aquatic ecosystems. It also introduces the general concepts of chemical biomarkers as they relate to global biogeochemical cycling. The application of chemical biomarkers in modern and/or ancient ecosystems is largely a function of the inherent structure and stability of the molecule, as well as the physicochemical environment of the system wherein it exists. In some cases, redox changes in sediments have allowed for greater preservation of biomarker compounds; in well-defined laminated sediments; for example, a strong case can be made for paleo-reconstruction of past organic matter composition sources. However, many of the labile chemical biomarkers may be lost or transformed within minutes to hours of being released from the cell from processes such as bacterial and/or metazoan grazing, cell lysis, and photochemical breakdown. The role of trophic effects versus large-scale physiochemical gradients in preserving or destroying the integrity of chemical biomarkers varies greatly across different ecosystems. These effects are discussed as they relate to aquatic systems such as lakes, estuaries, and oceans.Less
This chapter provides a brief historical account of the success and limitations of using chemical biomarkers in aquatic ecosystems. It also introduces the general concepts of chemical biomarkers as they relate to global biogeochemical cycling. The application of chemical biomarkers in modern and/or ancient ecosystems is largely a function of the inherent structure and stability of the molecule, as well as the physicochemical environment of the system wherein it exists. In some cases, redox changes in sediments have allowed for greater preservation of biomarker compounds; in well-defined laminated sediments; for example, a strong case can be made for paleo-reconstruction of past organic matter composition sources. However, many of the labile chemical biomarkers may be lost or transformed within minutes to hours of being released from the cell from processes such as bacterial and/or metazoan grazing, cell lysis, and photochemical breakdown. The role of trophic effects versus large-scale physiochemical gradients in preserving or destroying the integrity of chemical biomarkers varies greatly across different ecosystems. These effects are discussed as they relate to aquatic systems such as lakes, estuaries, and oceans.
Robert R. Dunn, Benoit Guénard, Michael D. Weiser, and Nathan J. Sanders
- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780199544639
- eISBN:
- 9780191720192
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199544639.003.0003
- Subject:
- Biology, Ecology, Animal Biology
One of the key questions in ecology is what drives species diversity patterns. Generally ant diversity decreases with increasing latitude, and elevation. While a host of mechanisms to explain these ...
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One of the key questions in ecology is what drives species diversity patterns. Generally ant diversity decreases with increasing latitude, and elevation. While a host of mechanisms to explain these patterns has been proposed, the six most likely hypotheses include differences in speciation and extinction rates, geographic area, geometric constraints, species‐energy theory, and effective evolutionary age. Not only does ant diversity vary with latitude and elevation but there are also gradients in ant life history traits. Although there are only a handful of studies on ants, range size was found to increase with increasing elevation in accordance with Rapoport's rule predictions. Similarly in accordance with Bergmann's rule, ant body size tends to increase with latitude and elevation. Gradients in diversity can have consequences for predation rates, and mutualisms.Less
One of the key questions in ecology is what drives species diversity patterns. Generally ant diversity decreases with increasing latitude, and elevation. While a host of mechanisms to explain these patterns has been proposed, the six most likely hypotheses include differences in speciation and extinction rates, geographic area, geometric constraints, species‐energy theory, and effective evolutionary age. Not only does ant diversity vary with latitude and elevation but there are also gradients in ant life history traits. Although there are only a handful of studies on ants, range size was found to increase with increasing elevation in accordance with Rapoport's rule predictions. Similarly in accordance with Bergmann's rule, ant body size tends to increase with latitude and elevation. Gradients in diversity can have consequences for predation rates, and mutualisms.
Alan Gilchrist
- Published in print:
- 2006
- Published Online:
- September 2007
- ISBN:
- 9780195187168
- eISBN:
- 9780199786725
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195187168.003.0005
- Subject:
- Psychology, Clinical Psychology
Chronologically the fourth period of lightness theory, also known as the contrast period, extended from World War II until the end of the 1960s. Ideologically, however, it began at the end of the ...
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Chronologically the fourth period of lightness theory, also known as the contrast period, extended from World War II until the end of the 1960s. Ideologically, however, it began at the end of the 19th century, ignoring the intervening work of David Katz and the Gestalt psychologists. The contrast period was dominated by the behaviorists, who believed in the physiological mechanism of lateral inhibition. Contrast theorists took up the debate right where it had been left off in 1900, amidst the Ewald Hering/Hermann von Helmholtz controversy — and they sided overwhelmingly with Hering. Two theories came to dominate this period, those of D. Jameson and L. Hurvich and of Tom Cornsweet, both derived from Hering. Other important theories of the time, such as Harry Helson's adaptation-level theory and Hans Wallach's ratio theory, were assimilated to Hering's theory of contrast.Less
Chronologically the fourth period of lightness theory, also known as the contrast period, extended from World War II until the end of the 1960s. Ideologically, however, it began at the end of the 19th century, ignoring the intervening work of David Katz and the Gestalt psychologists. The contrast period was dominated by the behaviorists, who believed in the physiological mechanism of lateral inhibition. Contrast theorists took up the debate right where it had been left off in 1900, amidst the Ewald Hering/Hermann von Helmholtz controversy — and they sided overwhelmingly with Hering. Two theories came to dominate this period, those of D. Jameson and L. Hurvich and of Tom Cornsweet, both derived from Hering. Other important theories of the time, such as Harry Helson's adaptation-level theory and Hans Wallach's ratio theory, were assimilated to Hering's theory of contrast.
Scott Eddie
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780198201663
- eISBN:
- 9780191718434
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198201663.003.0008
- Subject:
- History, European Modern History
This chapter shows a clear East-West gradient in a land yield index by province, based on Kreis data from the land tax cadastre (Grundsteuerveranlagung) of the early 1860s. The province of Saxony ...
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This chapter shows a clear East-West gradient in a land yield index by province, based on Kreis data from the land tax cadastre (Grundsteuerveranlagung) of the early 1860s. The province of Saxony stands out as having the highest quality land in general, whereas East Prussia had generally the lowest. Cluster analysis is used to classify large properties by their land-use profiles. The general structure of the clusters proved remarkably stable over time. The chapter further examines the clusters by total area and total tax value contained within each cluster. Bourgeois land owners tended to concentrate their holdings in arable agriculture, the nobility in properties with mixed land use, and the Prussian state in forestry. Other land owners as a group had about half the tax value of their holdings in properties specialized on arable agriculture, with the rest spread out over all different combinations of land use.Less
This chapter shows a clear East-West gradient in a land yield index by province, based on Kreis data from the land tax cadastre (Grundsteuerveranlagung) of the early 1860s. The province of Saxony stands out as having the highest quality land in general, whereas East Prussia had generally the lowest. Cluster analysis is used to classify large properties by their land-use profiles. The general structure of the clusters proved remarkably stable over time. The chapter further examines the clusters by total area and total tax value contained within each cluster. Bourgeois land owners tended to concentrate their holdings in arable agriculture, the nobility in properties with mixed land use, and the Prussian state in forestry. Other land owners as a group had about half the tax value of their holdings in properties specialized on arable agriculture, with the rest spread out over all different combinations of land use.
Kevin J. Gaston
- Published in print:
- 2010
- Published Online:
- February 2010
- ISBN:
- 9780199554232
- eISBN:
- 9780191720666
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199554232.003.0003
- Subject:
- Biology, Ecology, Biodiversity / Conservation Biology
Kevin J. Gaston defines biodiversity and lays out obstacles to its better understanding in this chapter. Biodiversity is the variety of life in all of its many manifestations. This variety can ...
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Kevin J. Gaston defines biodiversity and lays out obstacles to its better understanding in this chapter. Biodiversity is the variety of life in all of its many manifestations. This variety can usefully be thought of in terms of three hierarchical sets of elements, which capture different facets: genetic diversity, organismal diversity, and ecological diversity. There is by definition no single measure of biodiversity, although two different kinds of measures (number and heterogeneity) can be distinguished. Pragmatically, and rather restrictively, biodiversity tends in the main to be measured in terms of a number measures of organismal diversity, and especially species richness. Biodiversity has been present for much of the history of the Earth, but the levels have changed dramatically and have proven challenging to document reliably. Biodiversity is variably distributed across the Earth, although some marked spatial gradients seem common to numerous higher taxonomic groups. The obstacles to an improved understanding of biodiversity are: (i) its sheer magnitude and complexity; (ii) the biases of the fossil record and the apparent variability in rates of molecular evolution; (iii) the relative paucity of quantitative sampling over much of the planet; and (iv) that levels and patterns of biodiversity are being profoundly altered by human activities.Less
Kevin J. Gaston defines biodiversity and lays out obstacles to its better understanding in this chapter. Biodiversity is the variety of life in all of its many manifestations. This variety can usefully be thought of in terms of three hierarchical sets of elements, which capture different facets: genetic diversity, organismal diversity, and ecological diversity. There is by definition no single measure of biodiversity, although two different kinds of measures (number and heterogeneity) can be distinguished. Pragmatically, and rather restrictively, biodiversity tends in the main to be measured in terms of a number measures of organismal diversity, and especially species richness. Biodiversity has been present for much of the history of the Earth, but the levels have changed dramatically and have proven challenging to document reliably. Biodiversity is variably distributed across the Earth, although some marked spatial gradients seem common to numerous higher taxonomic groups. The obstacles to an improved understanding of biodiversity are: (i) its sheer magnitude and complexity; (ii) the biases of the fossil record and the apparent variability in rates of molecular evolution; (iii) the relative paucity of quantitative sampling over much of the planet; and (iv) that levels and patterns of biodiversity are being profoundly altered by human activities.
Bijan Mohammadi and Olivier Pironneau
- Published in print:
- 2009
- Published Online:
- February 2010
- ISBN:
- 9780199546909
- eISBN:
- 9780191720482
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199546909.003.0009
- Subject:
- Mathematics, Mathematical Physics
This chapter puts forward a general argument to support the use of approximate gradients within optimization loops integrated with mesh refinements. However, this does not justify all the procedures ...
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This chapter puts forward a general argument to support the use of approximate gradients within optimization loops integrated with mesh refinements. However, this does not justify all the procedures that are presented in the previous chapter. The chapter proves also that smoothers are essential. This part was done in collaboration with E. Polak and N. Dicesare.Less
This chapter puts forward a general argument to support the use of approximate gradients within optimization loops integrated with mesh refinements. However, this does not justify all the procedures that are presented in the previous chapter. The chapter proves also that smoothers are essential. This part was done in collaboration with E. Polak and N. Dicesare.
PETER K. STYS, STEPHEN G. WAXMAN, and BRUCE R. RANSOM
- Published in print:
- 1995
- Published Online:
- May 2009
- ISBN:
- 9780195082937
- eISBN:
- 9780199865802
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195082937.003.0015
- Subject:
- Neuroscience, Disorders of the Nervous System
Excitable cells are dependent on adequate transmembrane ion gradients for normal function. Electrochemical gradients of the major cations (Na+, K+, Ca2+, and Mg2+) and anions (Cl- and HCO3 ...
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Excitable cells are dependent on adequate transmembrane ion gradients for normal function. Electrochemical gradients of the major cations (Na+, K+, Ca2+, and Mg2+) and anions (Cl- and HCO3 -) permit excitable cells to carry out signaling, sensory transduction, and effector functions. Axons are similarly dependent on the same ion gradients for their function. This chapter discusses transporting systems that function to maintain or restore gradients.Less
Excitable cells are dependent on adequate transmembrane ion gradients for normal function. Electrochemical gradients of the major cations (Na+, K+, Ca2+, and Mg2+) and anions (Cl- and HCO3 -) permit excitable cells to carry out signaling, sensory transduction, and effector functions. Axons are similarly dependent on the same ion gradients for their function. This chapter discusses transporting systems that function to maintain or restore gradients.
Erich H. Kisi and Christopher J. Howard
- Published in print:
- 2008
- Published Online:
- January 2009
- ISBN:
- 9780198515944
- eISBN:
- 9780191705663
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198515944.003.0009
- Subject:
- Physics, Condensed Matter Physics / Materials
This chapter describes how diffraction peaks can be broadened, and sometimes their intensities altered, by microstructural effects. Much of the theory was developed for X-rays, but is also applicable ...
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This chapter describes how diffraction peaks can be broadened, and sometimes their intensities altered, by microstructural effects. Much of the theory was developed for X-rays, but is also applicable in the neutron case. Peaks are broadened due to small crystallite size, or the presence of microstrains, or both. The analysis may involve deconvolution, individual peak fitting, whole pattern fitting, and the Scherrer equation. Methods for handling anisotropic broadening are presented. The Williamson-Hall plot is shown to be useful when size and strain broadening both are present. The effects on peak shapes of chemical and physical gradients are considered in detail: strain gradients for example lead to domain wall scattering. The theory of broadening due to dislocations is presented, and illustrated by application to LaNi5. The effects of planar defects, such as stacking faults and twin boundaries, are also considered. Finally, the effect on intensities of texture (preferred orientation) is discussed.Less
This chapter describes how diffraction peaks can be broadened, and sometimes their intensities altered, by microstructural effects. Much of the theory was developed for X-rays, but is also applicable in the neutron case. Peaks are broadened due to small crystallite size, or the presence of microstrains, or both. The analysis may involve deconvolution, individual peak fitting, whole pattern fitting, and the Scherrer equation. Methods for handling anisotropic broadening are presented. The Williamson-Hall plot is shown to be useful when size and strain broadening both are present. The effects on peak shapes of chemical and physical gradients are considered in detail: strain gradients for example lead to domain wall scattering. The theory of broadening due to dislocations is presented, and illustrated by application to LaNi5. The effects of planar defects, such as stacking faults and twin boundaries, are also considered. Finally, the effect on intensities of texture (preferred orientation) is discussed.
