Charles Boyer and Krzysztof Galicki
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780198564959
- eISBN:
- 9780191713712
- Item type:
- book
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198564959.001.0001
- Subject:
- Mathematics, Geometry / Topology
Sasakian manifolds were first introduced in 1962. This book's main focus is on the intricate relationship between Sasakian and Kähler geometries, especially when the Kähler structure is that of an ...
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Sasakian manifolds were first introduced in 1962. This book's main focus is on the intricate relationship between Sasakian and Kähler geometries, especially when the Kähler structure is that of an algebraic variety. The book is divided into three parts. The first five chapters carefully prepare the stage for the proper introduction of the subject. After a brief discussion of G-structures, the reader is introduced to the theory of Riemannian foliations. A concise review of complex and Kähler geometry precedes a fairly detailed treatment of compact complex Kähler orbifolds. A discussion of the existence and obstruction theory of Kähler-Einstein metrics (Monge-Ampère problem) on complex compact orbifolds follows. The second part gives a careful discussion of contact structures in the Riemannian setting. Compact quasi-regular Sasakian manifolds emerge here as algebraic objects: they are orbifold circle bundles over compact projective algebraic orbifolds. After a discussion of symmetries of Sasakian manifolds in Chapter 8, the book looks at Sasakian structures on links of isolated hypersurface singularities in Chapter 9. What follows is a study of compact Sasakian manifolds in dimensions three and five focusing on the important notion of positivity. The latter is crucial in understanding the existence of Sasaki-Einstein and 3-Sasakian metrics, which are studied in Chapters 11 and 13. Chapter 12 gives a fairly brief description of quaternionic geometry which is a prerequisite for Chapter 13. The study of Sasaki-Einstein geometry was the original motivation for the book. The final chapter on Killing spinors discusses the properties of Sasaki-Einstein manifolds, which allow them to play an important role as certain models in the supersymmetric field theories of theoretical physics.Less
Sasakian manifolds were first introduced in 1962. This book's main focus is on the intricate relationship between Sasakian and Kähler geometries, especially when the Kähler structure is that of an algebraic variety. The book is divided into three parts. The first five chapters carefully prepare the stage for the proper introduction of the subject. After a brief discussion of G-structures, the reader is introduced to the theory of Riemannian foliations. A concise review of complex and Kähler geometry precedes a fairly detailed treatment of compact complex Kähler orbifolds. A discussion of the existence and obstruction theory of Kähler-Einstein metrics (Monge-Ampère problem) on complex compact orbifolds follows. The second part gives a careful discussion of contact structures in the Riemannian setting. Compact quasi-regular Sasakian manifolds emerge here as algebraic objects: they are orbifold circle bundles over compact projective algebraic orbifolds. After a discussion of symmetries of Sasakian manifolds in Chapter 8, the book looks at Sasakian structures on links of isolated hypersurface singularities in Chapter 9. What follows is a study of compact Sasakian manifolds in dimensions three and five focusing on the important notion of positivity. The latter is crucial in understanding the existence of Sasaki-Einstein and 3-Sasakian metrics, which are studied in Chapters 11 and 13. Chapter 12 gives a fairly brief description of quaternionic geometry which is a prerequisite for Chapter 13. The study of Sasaki-Einstein geometry was the original motivation for the book. The final chapter on Killing spinors discusses the properties of Sasaki-Einstein manifolds, which allow them to play an important role as certain models in the supersymmetric field theories of theoretical physics.
Charles P. Boyer and Krzysztof Galicki
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780198564959
- eISBN:
- 9780191713712
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198564959.003.0002
- Subject:
- Mathematics, Geometry / Topology
This chapter begins by introducing various geometries that play important roles in the way they relate to Sasakian structures. It espouses the point of view that a geometric structure is best ...
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This chapter begins by introducing various geometries that play important roles in the way they relate to Sasakian structures. It espouses the point of view that a geometric structure is best described as a G-structure which may or may not be (partially) integrable. Some selected topics include: Riemannian metrics, complex structures, symplectic structures, contact structures, quaternionic structures, group actions, pseudogroups, sheaves, bundles, connections, holonomy, curvature and integrability.Less
This chapter begins by introducing various geometries that play important roles in the way they relate to Sasakian structures. It espouses the point of view that a geometric structure is best described as a G-structure which may or may not be (partially) integrable. Some selected topics include: Riemannian metrics, complex structures, symplectic structures, contact structures, quaternionic structures, group actions, pseudogroups, sheaves, bundles, connections, holonomy, curvature and integrability.
Charles P. Boyer and Krzysztof Galicki
- Published in print:
- 2007
- Published Online:
- January 2008
- ISBN:
- 9780198564959
- eISBN:
- 9780191713712
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198564959.003.0004
- Subject:
- Mathematics, Geometry / Topology
This chapter reviews some basic facts about Kähler manifolds with special emphasis on projective algebraic varieties. All standard material is covered: complex structures, curvature properties, Hodge ...
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This chapter reviews some basic facts about Kähler manifolds with special emphasis on projective algebraic varieties. All standard material is covered: complex structures, curvature properties, Hodge theory, Chern classes, positivity and Fano varieties, line bundles and divisors. Of particular interest is Yau's famous proof of the Calabi conjecture which ends this chapter.Less
This chapter reviews some basic facts about Kähler manifolds with special emphasis on projective algebraic varieties. All standard material is covered: complex structures, curvature properties, Hodge theory, Chern classes, positivity and Fano varieties, line bundles and divisors. Of particular interest is Yau's famous proof of the Calabi conjecture which ends this chapter.
Frank Krueger and Jordan Grafman
- Published in print:
- 2008
- Published Online:
- May 2008
- ISBN:
- 9780195188370
- eISBN:
- 9780199870462
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195188370.003.0025
- Subject:
- Psychology, Cognitive Neuroscience
Event sequence knowledge is necessary for learning, planning, and performing activities of daily living. Clinical observations suggest that the prefrontal cortex (PFC) is crucial for goal-directed ...
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Event sequence knowledge is necessary for learning, planning, and performing activities of daily living. Clinical observations suggest that the prefrontal cortex (PFC) is crucial for goal-directed behavior such as carrying out plans, controlling a course of actions, or organizing everyday life routines. This chapter proposes a “representational” approach to PFC function, which assumes that the PFC (a) stores long-term memories of goal-oriented event sequence knowledge and (b) seeks to establish the format and categories according to which such information is stored. It argues that the human PFC stores a unique type of knowledge in the form of structured event complexes (SECs). SECs are representations composed of higher-order goal-oriented sequences of events that are involved in the planning and monitoring of complex behavior.Less
Event sequence knowledge is necessary for learning, planning, and performing activities of daily living. Clinical observations suggest that the prefrontal cortex (PFC) is crucial for goal-directed behavior such as carrying out plans, controlling a course of actions, or organizing everyday life routines. This chapter proposes a “representational” approach to PFC function, which assumes that the PFC (a) stores long-term memories of goal-oriented event sequence knowledge and (b) seeks to establish the format and categories according to which such information is stored. It argues that the human PFC stores a unique type of knowledge in the form of structured event complexes (SECs). SECs are representations composed of higher-order goal-oriented sequences of events that are involved in the planning and monitoring of complex behavior.
Mark Green, Phillip Griffiths, and Matt Kerr
- Published in print:
- 2012
- Published Online:
- October 2017
- ISBN:
- 9780691154244
- eISBN:
- 9781400842735
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691154244.003.0006
- Subject:
- Mathematics, Analysis
This chapter describes Hodge structures with a high degree of symmetry, and specifically complex multiplication Hodge structures or CM Hodge structures. It broadens the notion of CM type by defining ...
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This chapter describes Hodge structures with a high degree of symmetry, and specifically complex multiplication Hodge structures or CM Hodge structures. It broadens the notion of CM type by defining an n-orientation of a totally imaginary number field and constructs a precise correspondence between these and certain important kinds of CM Hodge structures. In the classical case of weight n = 1, the abelian variety associated to a CM type is recovered. The notion of the Kubota rank and reflex field associated to a CM Hodge structure is then generalized to the totally imaginary number field setting. When the Kubota rank is maximal, the CM Hodge structure is non-degenerate. The discussion also covers oriented imaginary number fields, Hodge structures with special endomorphisms, polarization and Mumford-Tate groups, and the Mumford-Tate group in the Galois case.Less
This chapter describes Hodge structures with a high degree of symmetry, and specifically complex multiplication Hodge structures or CM Hodge structures. It broadens the notion of CM type by defining an n-orientation of a totally imaginary number field and constructs a precise correspondence between these and certain important kinds of CM Hodge structures. In the classical case of weight n = 1, the abelian variety associated to a CM type is recovered. The notion of the Kubota rank and reflex field associated to a CM Hodge structure is then generalized to the totally imaginary number field setting. When the Kubota rank is maximal, the CM Hodge structure is non-degenerate. The discussion also covers oriented imaginary number fields, Hodge structures with special endomorphisms, polarization and Mumford-Tate groups, and the Mumford-Tate group in the Galois case.
Mark Green, Phillip Griffiths, and Matt Kerr
- Published in print:
- 2012
- Published Online:
- October 2017
- ISBN:
- 9780691154244
- eISBN:
- 9781400842735
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691154244.003.0008
- Subject:
- Mathematics, Analysis
This chapter develops an algorithm for determining all Mumford-Tate subdomains of a given period domain. The result is applied to the classification of all complex multiplication Hodge structures (CM ...
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This chapter develops an algorithm for determining all Mumford-Tate subdomains of a given period domain. The result is applied to the classification of all complex multiplication Hodge structures (CM Hodge structures) of rank 4 and when the weight n = 1 and n = 3, to an analysis of their Hodge tensors and endomorphism algebras, and the number of components of the Noether-Lefschetz locus. The result is that one has a complex but very rich arithmetic story. Of particular note is the intricate structure of the components of the Noether-Lefschetz loci in D and in its compact dual, and the two interesting cases where the Hodge tensors are generated in degrees 2 and 4. One application is that a particular class of period maps appearing in mirror symmetry never has image in a proper subdomain of D.Less
This chapter develops an algorithm for determining all Mumford-Tate subdomains of a given period domain. The result is applied to the classification of all complex multiplication Hodge structures (CM Hodge structures) of rank 4 and when the weight n = 1 and n = 3, to an analysis of their Hodge tensors and endomorphism algebras, and the number of components of the Noether-Lefschetz locus. The result is that one has a complex but very rich arithmetic story. Of particular note is the intricate structure of the components of the Noether-Lefschetz loci in D and in its compact dual, and the two interesting cases where the Hodge tensors are generated in degrees 2 and 4. One application is that a particular class of period maps appearing in mirror symmetry never has image in a proper subdomain of D.
Mark Green, Phillip Griffiths, and Matt Kerr
- Published in print:
- 2012
- Published Online:
- October 2017
- ISBN:
- 9780691154244
- eISBN:
- 9781400842735
- Item type:
- chapter
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691154244.003.0009
- Subject:
- Mathematics, Analysis
This chapter considers some arithmetic aspects of period maps with a geometric origin. It focuses on the situation Φ : S(ℂ) → Γ\D, where S parametrizes a family X → S of smooth, projective ...
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This chapter considers some arithmetic aspects of period maps with a geometric origin. It focuses on the situation Φ : S(ℂ) → Γ\D, where S parametrizes a family X → S of smooth, projective varieties defined over a number field k. The chapter recalls the notion of absolute Hodge classes (AH) and strongly absolute Hodge classes (SAH). The particular case when the Noether-Lefschetz locus consists of isolated points is alluded to in the discussion of complex multiplication Hodge structures (CM Hodge structures). A related observation is that one may formulate a variant of the “Grothendieck conjecture” in the setting of period maps and period domains. The chapter also describes a behavior of fields of definition under the period map, along with the existence and density of CM points in a motivic variation of Hodge structure.Less
This chapter considers some arithmetic aspects of period maps with a geometric origin. It focuses on the situation Φ : S(ℂ) → Γ\D, where S parametrizes a family X → S of smooth, projective varieties defined over a number field k. The chapter recalls the notion of absolute Hodge classes (AH) and strongly absolute Hodge classes (SAH). The particular case when the Noether-Lefschetz locus consists of isolated points is alluded to in the discussion of complex multiplication Hodge structures (CM Hodge structures). A related observation is that one may formulate a variant of the “Grothendieck conjecture” in the setting of period maps and period domains. The chapter also describes a behavior of fields of definition under the period map, along with the existence and density of CM points in a motivic variation of Hodge structure.
Jordan Grafman
- Published in print:
- 2006
- Published Online:
- May 2009
- ISBN:
- 9780195177619
- eISBN:
- 9780199864683
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195177619.003.0011
- Subject:
- Neuroscience, Sensory and Motor Systems, Behavioral Neuroscience
This chapter shows that key higher-level cognitive functions known as the executive functions are strongly associated with the human prefrontal cortex (HPFC). It argues that an important way to ...
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This chapter shows that key higher-level cognitive functions known as the executive functions are strongly associated with the human prefrontal cortex (HPFC). It argues that an important way to understand the functions of the HPFC is to adapt the representational model that has been the predominant approach to understanding the neuropsychological aspects of, for example, language processing and object recognition. The representational approach developed is based on the structured event complex framework. This framework claims that there are multiple subcomponents of higher-level knowledge that are stored throughout the HPFC as distinctive domains of memory. The chapter also argues that there are topographical distinctions in where these different aspects of knowledge are stored in the HPFC.Less
This chapter shows that key higher-level cognitive functions known as the executive functions are strongly associated with the human prefrontal cortex (HPFC). It argues that an important way to understand the functions of the HPFC is to adapt the representational model that has been the predominant approach to understanding the neuropsychological aspects of, for example, language processing and object recognition. The representational approach developed is based on the structured event complex framework. This framework claims that there are multiple subcomponents of higher-level knowledge that are stored throughout the HPFC as distinctive domains of memory. The chapter also argues that there are topographical distinctions in where these different aspects of knowledge are stored in the HPFC.
Alwyn Lishman
- Published in print:
- 2003
- Published Online:
- November 2011
- ISBN:
- 9780198515814
- eISBN:
- 9780191730498
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198515814.003.0014
- Subject:
- Palliative Care, Patient Care and End-of-Life Decision Making, Palliative Medicine Research
This concluding chapter discusses the personal experience of the author in dealing with palliative care and the concept of the user's voice, which is widely welcomed in seeking to refine the way ...
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This concluding chapter discusses the personal experience of the author in dealing with palliative care and the concept of the user's voice, which is widely welcomed in seeking to refine the way forward. It reveals that the common thread that unites the chapters in this book is a deep humanity, which is focused on improving the lot of the terminally ill. The chapter also shows that palliative care needs to operate within complex structures: organizational and even political. Alliances between diverse groups of people must be formed and financial limitations faced.Less
This concluding chapter discusses the personal experience of the author in dealing with palliative care and the concept of the user's voice, which is widely welcomed in seeking to refine the way forward. It reveals that the common thread that unites the chapters in this book is a deep humanity, which is focused on improving the lot of the terminally ill. The chapter also shows that palliative care needs to operate within complex structures: organizational and even political. Alliances between diverse groups of people must be formed and financial limitations faced.
Peter G. Bruce and Yuri G. Andreev
- Published in print:
- 2006
- Published Online:
- January 2010
- ISBN:
- 9780199205530
- eISBN:
- 9780191718076
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199205530.003.0016
- Subject:
- Physics, Condensed Matter Physics / Materials
The chapter describes a simulated annealing approach to solving highly flexible molecular crystal structures. Particular attention is paid to the description of the models whose position, ...
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The chapter describes a simulated annealing approach to solving highly flexible molecular crystal structures. Particular attention is paid to the description of the models whose position, orientation, and conformation are to be optimised against the observed powder diffraction data. The mathematics underlying the construction and positioning of the models is given. The approach is illustrated with the solution of various polymer: salt complex crystal structures. The chapter concludes with a discussion of the likely limits of structural complexity that might be addressed by such an approach.Less
The chapter describes a simulated annealing approach to solving highly flexible molecular crystal structures. Particular attention is paid to the description of the models whose position, orientation, and conformation are to be optimised against the observed powder diffraction data. The mathematics underlying the construction and positioning of the models is given. The approach is illustrated with the solution of various polymer: salt complex crystal structures. The chapter concludes with a discussion of the likely limits of structural complexity that might be addressed by such an approach.
Aron K. Barbey, Frank Krueger, and Jordan Grafman
- Published in print:
- 2011
- Published Online:
- September 2011
- ISBN:
- 9780195395518
- eISBN:
- 9780199897230
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780195395518.003.0018
- Subject:
- Psychology, Cognitive Psychology, Cognitive Neuroscience
This chapter develops an integrative cognitive neuroscience framework for understanding counterfactual reasoning on the basis of structured event complexes (SECs) in the human prefrontal cortex ...
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This chapter develops an integrative cognitive neuroscience framework for understanding counterfactual reasoning on the basis of structured event complexes (SECs) in the human prefrontal cortex (PFC). The reviewed evidence in support of the SEC framework confirms the importance and uniqueness of the human PFC for representing knowledge in the form of cognitive events and action sequences. It is argued that SECs are the key to understanding the human ability to represent mental models of events, which guide the selection of goal-directed action sequences and the on-line updating of behavior based on past outcomes or anticipated future events.Less
This chapter develops an integrative cognitive neuroscience framework for understanding counterfactual reasoning on the basis of structured event complexes (SECs) in the human prefrontal cortex (PFC). The reviewed evidence in support of the SEC framework confirms the importance and uniqueness of the human PFC for representing knowledge in the form of cognitive events and action sequences. It is argued that SECs are the key to understanding the human ability to represent mental models of events, which guide the selection of goal-directed action sequences and the on-line updating of behavior based on past outcomes or anticipated future events.
Dusa McDuff and Dietmar Salamon
- Published in print:
- 2017
- Published Online:
- June 2017
- ISBN:
- 9780198794899
- eISBN:
- 9780191836411
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198794899.003.0005
- Subject:
- Mathematics, Analysis, Geometry / Topology
The chapter begins with a general discussion of almost complex structures on symplectic manifolds and then addresses the problem of integrability. Subsequent sections discuss a variety of examples of ...
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The chapter begins with a general discussion of almost complex structures on symplectic manifolds and then addresses the problem of integrability. Subsequent sections discuss a variety of examples of Kähler manifolds, in particular those of complex dimension two, and show how to compute the Chern classes and Betti numbers of hypersurfaces in complex projective space. The last section is a brief introduction to the theory of J-holomorphic curves.Less
The chapter begins with a general discussion of almost complex structures on symplectic manifolds and then addresses the problem of integrability. Subsequent sections discuss a variety of examples of Kähler manifolds, in particular those of complex dimension two, and show how to compute the Chern classes and Betti numbers of hypersurfaces in complex projective space. The last section is a brief introduction to the theory of J-holomorphic curves.
Marco Gualtieri
- Published in print:
- 2018
- Published Online:
- December 2018
- ISBN:
- 9780198802020
- eISBN:
- 9780191869068
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198802020.003.0023
- Subject:
- Mathematics, Geometry / Topology
This chapter provides a new characterization of generalized Kähler structures in terms of the corresponding complex Dirac structures. It then gives an alternative proof of Hitchin’s partial ...
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This chapter provides a new characterization of generalized Kähler structures in terms of the corresponding complex Dirac structures. It then gives an alternative proof of Hitchin’s partial unobstructedness for holomorphic Poisson structures. Its main application is to show that there is a corresponding unobstructedness result for arbitrary generalized Kähler structures. That is, it shows that any generalized Kähler structure may be deformed in such a way that one of its underlying holomorphic Poisson structures remains fixed, while the other deforms via Hitchin’s deformation. Finally, it indicates a close relationship between this deformation and the notion of a Hamiltonian family of Poisson structures.Less
This chapter provides a new characterization of generalized Kähler structures in terms of the corresponding complex Dirac structures. It then gives an alternative proof of Hitchin’s partial unobstructedness for holomorphic Poisson structures. Its main application is to show that there is a corresponding unobstructedness result for arbitrary generalized Kähler structures. That is, it shows that any generalized Kähler structure may be deformed in such a way that one of its underlying holomorphic Poisson structures remains fixed, while the other deforms via Hitchin’s deformation. Finally, it indicates a close relationship between this deformation and the notion of a Hamiltonian family of Poisson structures.
Paul Charbonneau
- Published in print:
- 2017
- Published Online:
- May 2018
- ISBN:
- 9780691176840
- eISBN:
- 9781400885497
- Item type:
- book
- Publisher:
- Princeton University Press
- DOI:
- 10.23943/princeton/9780691176840.001.0001
- Subject:
- Computer Science, Programming
This book provides a short, hands-on introduction to the science of complexity using simple computational models of natural complex systems—with models and exercises drawn from physics, chemistry, ...
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This book provides a short, hands-on introduction to the science of complexity using simple computational models of natural complex systems—with models and exercises drawn from physics, chemistry, geology, and biology. By working through the models and engaging in additional computational explorations suggested at the end of each chapter, readers very quickly develop an understanding of how complex structures and behaviors can emerge in natural phenomena as diverse as avalanches, forest fires, earthquakes, chemical reactions, animal flocks, and epidemic diseases. This book provides the necessary topical background, complete source codes in Python, and detailed explanations for all computational models. Ideal for undergraduates, beginning graduate students, and researchers in the physical and natural sciences, this unique handbook requires no advanced mathematical knowledge or programming skills and is suitable for self-learners with a working knowledge of precalculus and high-school physics. The book enables readers to identify and quantify common underlying structural and dynamical patterns shared by the various systems and phenomena it examines, so that they can form their own answers to the questions of what natural complexity is and how it arises.Less
This book provides a short, hands-on introduction to the science of complexity using simple computational models of natural complex systems—with models and exercises drawn from physics, chemistry, geology, and biology. By working through the models and engaging in additional computational explorations suggested at the end of each chapter, readers very quickly develop an understanding of how complex structures and behaviors can emerge in natural phenomena as diverse as avalanches, forest fires, earthquakes, chemical reactions, animal flocks, and epidemic diseases. This book provides the necessary topical background, complete source codes in Python, and detailed explanations for all computational models. Ideal for undergraduates, beginning graduate students, and researchers in the physical and natural sciences, this unique handbook requires no advanced mathematical knowledge or programming skills and is suitable for self-learners with a working knowledge of precalculus and high-school physics. The book enables readers to identify and quantify common underlying structural and dynamical patterns shared by the various systems and phenomena it examines, so that they can form their own answers to the questions of what natural complexity is and how it arises.
Simon Donaldson
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780198526391
- eISBN:
- 9780191774874
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198526391.003.0013
- Subject:
- Mathematics, Geometry / Topology, Analysis
This chapter first examines almost-complex structures, Beltrami differentials, and the integrability theorem. It then discusses deformations and cohomology.
This chapter first examines almost-complex structures, Beltrami differentials, and the integrability theorem. It then discusses deformations and cohomology.
Tim Lenton and Andrew Watson
- Published in print:
- 2011
- Published Online:
- December 2013
- ISBN:
- 9780199587049
- eISBN:
- 9780191775031
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199587049.003.0020
- Subject:
- Physics, Geophysics, Atmospheric and Environmental Physics
This chapter endeavours to review the similarities between what is happening now and the past revolutions. There are several common features to the great revolutions that have made the present Earth. ...
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This chapter endeavours to review the similarities between what is happening now and the past revolutions. There are several common features to the great revolutions that have made the present Earth. These can be broadly categorised as the main characteristics of change, and the features which must emerge for it to be ‘successful’ – in the sense that permanent change persists and includes a thriving biosphere. Two out of the three past revolutions have been underlain by a step change in information transmission between living organisms. An increase in the amount of information that can be passed on allows life to build more complex structures. Complex structures can, in turn, improve the information-transmission mechanisms, allowing more information to be passed on, so these two processes mutually reinforce one another.Less
This chapter endeavours to review the similarities between what is happening now and the past revolutions. There are several common features to the great revolutions that have made the present Earth. These can be broadly categorised as the main characteristics of change, and the features which must emerge for it to be ‘successful’ – in the sense that permanent change persists and includes a thriving biosphere. Two out of the three past revolutions have been underlain by a step change in information transmission between living organisms. An increase in the amount of information that can be passed on allows life to build more complex structures. Complex structures can, in turn, improve the information-transmission mechanisms, allowing more information to be passed on, so these two processes mutually reinforce one another.
Kevin L. O’Hara
- Published in print:
- 2014
- Published Online:
- October 2014
- ISBN:
- 9780198703068
- eISBN:
- 9780191788796
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780198703068.003.0010
- Subject:
- Biology, Plant Sciences and Forestry
There is a growing, international interest in transforming even-aged to multiaged stands. There are many possible pathways for transformation or conversion of stands, and many different possible ...
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There is a growing, international interest in transforming even-aged to multiaged stands. There are many possible pathways for transformation or conversion of stands, and many different possible multiaged stand structures. These can include relatively simple stand structures, such as those with only two age classes, or more complex stand structure. The transformation process typically will take longer with greater complexity in the desired target structure. Transformation typically begins with a treatment that regenerates a new age class of trees. Constraints to transformation include having a sufficiently stable even-aged stand to treat. Many even-aged stands will be too dense to transform. In other cases, trees may be too old to survive a long transformation process. The silviculture of transformation should also be highly adaptive rather than assuming preestablished plans will suffice without adjustments later in the transformation process. Transformation targets should be flexible, as should the treatment regimes that are used to achieve these targets.Less
There is a growing, international interest in transforming even-aged to multiaged stands. There are many possible pathways for transformation or conversion of stands, and many different possible multiaged stand structures. These can include relatively simple stand structures, such as those with only two age classes, or more complex stand structure. The transformation process typically will take longer with greater complexity in the desired target structure. Transformation typically begins with a treatment that regenerates a new age class of trees. Constraints to transformation include having a sufficiently stable even-aged stand to treat. Many even-aged stands will be too dense to transform. In other cases, trees may be too old to survive a long transformation process. The silviculture of transformation should also be highly adaptive rather than assuming preestablished plans will suffice without adjustments later in the transformation process. Transformation targets should be flexible, as should the treatment regimes that are used to achieve these targets.
Markus Eberl
- Published in print:
- 2017
- Published Online:
- May 2018
- ISBN:
- 9780813056555
- eISBN:
- 9780813053486
- Item type:
- chapter
- Publisher:
- University Press of Florida
- DOI:
- 10.5744/florida/9780813056555.003.0004
- Subject:
- History, Cultural History
Unlike earlier conceptions of society as homogeneous, modern models emphasize its factious nature. Correspondingly, it cannot be reduced to a structure; instead, it contains multiple, coexisting, and ...
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Unlike earlier conceptions of society as homogeneous, modern models emphasize its factious nature. Correspondingly, it cannot be reduced to a structure; instead, it contains multiple, coexisting, and even overlapping structures. Chapter 4 visualizes these complex structures as a Garden of Forking Paths in which worlds—some real, others imaginary—coexist. To plan their actions, individuals trace a coherent path between worlds. Their actions adhere to cultural, although not necessarily practical, logic. They deal with worlds differently and apply different modalities. The latter distinguishes innovators from others. The material nature of inventions exhibits interaction and adoption publicly. Therefore, individual decision-making interweaves, Gardens of Forking Paths overlap, and the resulting interferences map the structural changes in society.
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Unlike earlier conceptions of society as homogeneous, modern models emphasize its factious nature. Correspondingly, it cannot be reduced to a structure; instead, it contains multiple, coexisting, and even overlapping structures. Chapter 4 visualizes these complex structures as a Garden of Forking Paths in which worlds—some real, others imaginary—coexist. To plan their actions, individuals trace a coherent path between worlds. Their actions adhere to cultural, although not necessarily practical, logic. They deal with worlds differently and apply different modalities. The latter distinguishes innovators from others. The material nature of inventions exhibits interaction and adoption publicly. Therefore, individual decision-making interweaves, Gardens of Forking Paths overlap, and the resulting interferences map the structural changes in society.
Stefan Behrens, Gil R. Cavalcanti, and Ralph L. Klaasse
- Published in print:
- 2018
- Published Online:
- December 2018
- ISBN:
- 9780198802020
- eISBN:
- 9780191869068
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/oso/9780198802020.003.0015
- Subject:
- Mathematics, Geometry / Topology
This chapter shows that a 4-manifold admits a boundary Lefschetz fibration over the disc if and only if it is diffeomorphic to S1×S3#nCP¯2,#mCP2#nCP¯2 or #m(S2×S2). Given the relation between ...
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This chapter shows that a 4-manifold admits a boundary Lefschetz fibration over the disc if and only if it is diffeomorphic to S1×S3#nCP¯2,#mCP2#nCP¯2 or #m(S2×S2). Given the relation between boundary Lefschetz fibrations and stable generalized complex structures, the chapter concludes that the 4-manifolds S1×S3#nCP¯2,#(2m+1)CP2#nCP¯2 and #(2m+1)S2×S2 admit stable generalized complex structures whose type change locus has a single component and are the only 4-manifolds whose stable structure arises from boundary Lefschetz fibrations over the disc.Less
This chapter shows that a 4-manifold admits a boundary Lefschetz fibration over the disc if and only if it is diffeomorphic to S1×S3#nCP¯2,#mCP2#nCP¯2 or #m(S2×S2). Given the relation between boundary Lefschetz fibrations and stable generalized complex structures, the chapter concludes that the 4-manifolds S1×S3#nCP¯2,#(2m+1)CP2#nCP¯2 and #(2m+1)S2×S2 admit stable generalized complex structures whose type change locus has a single component and are the only 4-manifolds whose stable structure arises from boundary Lefschetz fibrations over the disc.
Edward Gibson, Harry Tily, and Evelina Fedorenko
- Published in print:
- 2013
- Published Online:
- September 2013
- ISBN:
- 9780199677139
- eISBN:
- 9780191756368
- Item type:
- chapter
- Publisher:
- Oxford University Press
- DOI:
- 10.1093/acprof:oso/9780199677139.003.0006
- Subject:
- Linguistics, Psycholinguistics / Neurolinguistics / Cognitive Linguistics, Theoretical Linguistics
This paper reports two self-paced reading experiments investigating syntactically complex English structures. Evidence from both experiments provides support for working-memory-based accounts of ...
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This paper reports two self-paced reading experiments investigating syntactically complex English structures. Evidence from both experiments provides support for working-memory-based accounts of syntactic complexity, including both decay-based and interference-based components. Furthermore, this evidence is not easily explained by reanalysis- or experience-based accounts. However, neither a purely memory-based nor a purely experience-based account will explain all previously reported patterns of sentence processing data from the literature. As a result, a broad-coverage account of processing complexity will almost certainly have to include both (i) a mechanism for keeping track of our linguistic experiences and then using this knowledge to form expectations about the likelihoods of various upcoming elements, and (ii) a memory component engaged when dependencies are formed in the course of online comprehension.Less
This paper reports two self-paced reading experiments investigating syntactically complex English structures. Evidence from both experiments provides support for working-memory-based accounts of syntactic complexity, including both decay-based and interference-based components. Furthermore, this evidence is not easily explained by reanalysis- or experience-based accounts. However, neither a purely memory-based nor a purely experience-based account will explain all previously reported patterns of sentence processing data from the literature. As a result, a broad-coverage account of processing complexity will almost certainly have to include both (i) a mechanism for keeping track of our linguistic experiences and then using this knowledge to form expectations about the likelihoods of various upcoming elements, and (ii) a memory component engaged when dependencies are formed in the course of online comprehension.
