bluuebunny/crossref_metadata_2025 huggingface dataset:
When do 4-month-olds remember the ‘what’ and ‘where’ of hidden objects?
Authors: Mareschal Denis , Bremner Andrew J
Published: November 2023

The dual stream hypothesis is one of the most important heuristic frameworks for understanding the development of early human infant– object interactions. Electrophysiological evidence suggests that both dorsal and ventral streams are at least partially functional from a very young age. However, the two streams may not be functionally integrated until well into the second year of life (DeLoache et al. 2004). In this chapter, we present evidence from early infancy that the two streams are initially poorly integrated.
The development of human conceptual representations: A case study
Authors: Carey Susan , Sarnecka Barbara W
Published: November 2023

This chapter discusses a uniquely human learning mechanism – conceptual-role bootstrapping – whereby external symbolic systems (especially language) enable the creation of new, internal representational resources. The process is described in general terms and is also illustrated with a specific case: the acquisition of concepts for positive integers (one, two, three, etc.). First, the core knowledge systems that have numerical content are described and it is shown that none of these systems alone is capable of representing the positive integers. Next, children’s typical pattern of acquisition of the positive integers is described.
Spatial cognitive development following early focal brain injury: Evidence for adaptive change in brain and cognition
Authors: Stiles Joan , Paul Brianna , Hesselink John R
Published: November 2023

The field of developmental cognitive neuroscience has grown exponentially over the last two decades. The body of findings from both animal and human studies that has emerged has fundamentally changed the way we think about development. The age-old question of nature versus nurture is rapidly losing relevance as study after study demonstrates the essential role of the interaction between biology and experience in development. Development is principled, but dynamic, relying on the careful balance between progressive commitment to stable basic functional systems, while retaining the capacity for adaptation when the demands on the organism change.
Modules
Authors: Cameron Peter J
Published: November 2023

A module bears the same relationship to a vector space as a ring does to a ﬁeld. As this suggests, modules exist in much greater profusion than do vector spaces. We know everything about a vector space over a given field F once we know its dimension; but to specify a module, more detailed information is required. One of the themes of modern algebra is that the modules for a given ring capture a good deal of the structure of the ring. Our main goal in this chapter is the description of modules over Euclidean domains. The structure theorem tells us about finitely generated abelian groups, and also gives us canonical forms for matrices over fields.
Quasiconformal Maps and Teichmϋller Theory
Authors: Fletcher A , Markovic V
Published: November 2023

Based on a series of graduate lectures given by Vladimir Markovic at the University of Warwick in spring 2003, this book is accessible to those with a grounding in complex analysis looking for an introduction to the theory of quasiconformal maps and Teichmüller theory. Assuming some familiarity with Riemann surfaces and hyperbolic geometry, topics covered include the Grötzch argument, analytical properties of quasiconformal maps, the Beltrami differential equation, holomorphic motions and Teichmüller spaces. Where proofs are omitted, references to where they may be found are always given, and the text is clearly illustrated throughout with diagrams, examples, and exercises for the reader.
Synthesizing ecological experiments and observational data with hierarchical Bayes
Authors: Clark James S , LaDeau Shannon
Published: November 2023

Ecological field experiments rarely unfold as planned. The design and scale of observations can change due to unforeseeable changes in the environment and the emergence of new information. The subjects themselves can change in ways that make the original design untenable. Traditional models have limited flexibility to accommodate such complications, and they are not of much use for assimilation of information that comes from different sources.
Introduction
Authors: Katz Laura A , Bhattacharya Debashish
Published: November 2023

Microbial eukaryotes (i.e. protists), defined as eukaryotes that are neither plants, animals, nor fungi, are essential to many aspects of human health and the environment. These organisms represent at least 1500 million years of evolution, comprise the bulk of eukaryotic lineages, and include members with many key evolutionary innovations. Furthermore, because plants, animals, and fungi arose independently from within microbial groups, elucidating the origins and genetic developments within eukaryotic micro-organisms are necessary to understand fully the evolution of these macroscopic lineages. Hence, genomic studies of eukaryotic microbes are vital for deciphering the biodiversity of life on Earth.
The nuts and bolts of sequencing protist genomes
Authors: Bartholomeu Daniella C , Hall, Neil , Carlton Jane M
Published: November 2023

The availability of the complete genome sequence of an organism is an essential step towards obtaining a comprehensive understanding of the organism’s biology. In this regard, the species that make up the group Protista are important sequencing targets since: (i) many are human or animal pathogens of medical or veterinary importance, responsible for causing widespread morbidity and mortality; (ii) comparative genome analysis of freeliving versus parasitic protists may provide a deeper understanding of the evolution of pathogenic processes; (iii) genome sequencing of eukaryotic taxa will yield insights into key events in eukaryote evolution, such as cellular compartmentalization and origin of cytoskeletal structures; and (iv) due to their paraphyletic nature, sequencing protists from diverse groups representing successive lineages is of tremendous benefit for inferences in comparative genomics.
The genome of Entamoeba histolytica
Authors: Clark C Graham
Published: November 2023

Among the parasitic microbial eukaryote, Entamoeba histolytica ranks second behind the malaria parasites as a cause of human mortality. The WHO (1998) estimates that as many as 70 000 people die each year from the diseases it causes – primarily amoebic colitis and amoebic liver abscess. The number of people infected is much higher, perhaps as high as 50 million. The reason why so few infections become symptomatic is unknown and all infected individuals are considered to be at risk of developing disease.
Hypnotic Regulation Of Consciousness And The Pain Neuromatrix
Authors: Boly Mélanie , Faymonville Marie-Elisabeth , Vogt Brent A , Maquet, Pierre , Laureys Steven
Published: November 2023

Since mankind ‘s early history, hypnosis has been used as a therapeutic tool (De Betz and Sunnen 1985). Scientific papers have aimed to demonstrate its efficacy in the treatment of pain, gastrointestinal and dermatological pathologies, depression, anxiety, stress and habit disorders, to name but a few. Unfortunately, there is not a generally accepted definition of hypnosis. For many authors, it is seen as a state of focused attention, concentration and inner absorption with a relative suspension of peripheral awareness. We have all experienced similar states many times but do not usually call it hypnosis (e.g. being so absorbed in thought while doing something that we fail to notice what is happening around us). The Executive Committee of the American Psychological Association-Division of Psychological Hypnosis (1994) has constructed a definition from the multiplicity of positions of a number of researchers advocating differing theoretical perspectives.
On The Contribution Of Neurophysiology To Hypnosis Research: Current State And Future Directions
Authors: Burgess Adrian
Published: November 2023

One of the most interesting and productive developments in hypnosis research over the last 15 years has been the growth in the number of studies that incorporate measures of neurophysiological function. Typically these studies involve samples of extreme participants with high and low susceptibility measured before and after hypnotic induction with a concurrent neurophysiological measure such as the encephalogram (EEG)1 or functional magnetic resonance imaging (fMRI). These studies, which we might conveniently refer to as provocation tests as hypnosis is used to provoke a change in neural function, have often reported that highly susceptible participants show a change in brain physiology following hypnotic induction that is not seen before induction and is not seen in participants with low susceptibility even after induction. The inference made from these observations, either implicitly or explicitly, is that hypnotic induction effects a state change in the brains of participants who enter a hypnotized state. As such, these studies have been used as some of the most potent ammunition available in the long-standing controversy between state and non-state theorists.
The Experience Of Agency And Hypnosis From An Evolutionary Perspective
Authors: Ray William J
Published: November 2023

Psychology is just beginning to come to grips with the manner in which evolutionary thinking can impact and shape our current conceptualizations of physiological processes. This is somewhat surprising since Darwin suggested over 150 years ago that the theoretical underpinning of psychology would come from evolutionary theory. However, the realization of this possibility has been delayed partly from an infatuation with a potentially simple scientific view that ignored internal processes and a metatheory that ignored bio- logical foundations of human behaviour and experience. At the beginning of the twenty- first century, we are again returning to a scientific exploration of internal process including consciousness and the hypnotic experience.
Taut Foliations
Authors: Calegari Danny
Published: November 2023

In this chapter we introduce the main objects of interest in this book: taut foliations. Before we discuss such objects however, we must quickly review some of the basic elements of the theory of foliations.
The emergence of consequential thought: evidence from neuroscience
Authors: Baird* Abigail A , Fugelsang Jonathan A
Published: November 2023

One’s ability to imagine alternative outcomes and understand the consequences of those outcomes is an essential component of human reasoning. Such counterfactual thinking typically involves imagining a set of circumstances leading up to an event that may have had a different outcome if only a critical preceding event did not take place. For example, consider the case in which an individual runs over a pedestrian while taking an alternative route home to drop off a coworker. Had the coworker not requested a ride home, the driver might not have taken the alternative route, and thus not struck the pedestrian. Given this set of circumstances, an individual can mutate the events preceding the outcome and judge the degree to which certain mutations could change the outcome (e.g. the consequences of their behaviour).
Responsibility and punishment: whose mind? A response
Authors: Goodenough Oliver R
Published: November 2023

The essays collected in this issue demonstrate how the discoveries of cognitive neuroscience are rapidly expanding our understanding of the workings of the human brain. As our models of human mental processes improve, they are beginning to inform debates in other fields. In the law, the rules for assessing criminal responsibility have become the object of such an examination, both in essays within this issue (Baird & Fugelsang 2004; Greene & Cohen 2004; Jones 2004; Sapolsky 2004) and elsewhere (e.g. Lewis 1998; Reider 1998; Winslade 2002; see also Morse 2004).
Population Dynamics
Authors: Field Timothy R
Published: November 2023

The chapter is organized as follows. We begin in Section 7.1 with a discussion of the dynamics of the scattering cross-section and characterize this process in terms of a higher order transition process for a discrete scattering population. This is specialized to the case of the birth–death–immigration (BDI) model in Section 7.2. As the size of the population becomes asymptotically large, in Section 7.3, we obtain a corresponding limiting description in terms of a normalized continuous process, whose probability density obeys the Kramers–Moyal equation. In doing so we elucidate under what circumstances such a continuous process is a diffusion. As a special case we recover the diffusion model applied to scattering by Jakeman (1980) that corresponds to the BDI model, i.e. for the case of first-order transitions of birth, death and immigration.
Non-Linear Dynamics Of Sea Clutter
Authors: Field Timothy R
Published: November 2023

We review experimental evidence for the non-linearity of sea clutter and the role of the z-parameter or Mann–Whitney rank-sum statistic in quantifying this nonlinear behaviour in the context of a hybrid amplitude modulation (AM)/frequency modulation (FM) model for sea clutter, viewed as a cyclostationary process. An independent theoretical derivation of the stochastic dynamics of radar scattering in a sea clutter environment, in terms of a pair of coupled stochastic differential equations (SDEs) for the received envelope and radar cross-section (RCS), enables the identification of non-linearity in terms of the shape parameter for the RCS. We are led to conclude that, from both experimental and theoretical points of view, the dynamics of sea clutter are non-linear with a consistent degree of non-linearity that is determined by the sea state.
Markov chains
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

Show that any sequence of independent random variables taking values in the countable set S is a Markov chain. Under what condition is this chain homogeneous? A die is rolled repeatedly. Which of the following are Markov chains? For those that are, supply the transition matrix.
Convergence of random variables
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

Construct an example to show that the convergence in distribution of Xn to X does not imply the convergence of the unique medians of the sequence X n.
Random processes
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

The two tellers in a bank each take an exponentially distributed time to deal with any customer; their parameters are λ and μ respectively. You arrive to find exactly two customers present, each occupying a teller.
Queues
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

Suppose now that the random walker of Exercise (1) delays its steps in the following way. When at the point n, it waits a random length of time having the exponential distribution with parameter 0n before moving to its next position; different ‘holding times’ are independent of each other and of further information concerning the steps of the walk.
Diffusion processes
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

Write down Bartlett’s equation in the case of the Wiener process D having drift m and instantaneous variance 1, and solve it subject to the boundary condition D(0) = 0.
Random variables and their distributions
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

Quantities governed by randomness correspond to functions on the probability space called random variables. The value taken by a random variable is subject to chance, and the associated likelihoods are described by a function called the distribution function. Two important classes of random variables are discussed, namely discrete variables and continuous variables. The law of averages, known also as the law of large numbers, states that the proportion of successes in a long run of independent trials converges to the probability of success in any one trial. This result provides a mathematical basis for a philosophical view of probability based on repeated experimentation. Worked examples involving random variables and their distributions are included, and the chapter terminates with sections on random vectors and on Monte Carlo simulation.
Stationary processes
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

The theory of stationary processes, with discrete or continuous parameter, is developed. Autocovariances and spectral distributions are introduced. A theory of stochastic integration is developed for functions integrated against a stochastic process, and this theory is used to obtain a representation of a stationary process known as the spectral theorem. A result of major importance is the ergodic theorem, which explains the convergence of successive averages of a stationary process. Ergodic theorems are presented for weakly and strongly stationary processes. The final section is an introduction to Gaussian processes.
Queues
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

A queue may be specified by its arrival process and its queueing and service disciplines. Queues with exponentially distributed interarrival and service times are the easiest to study, since such processes are Markov chains. Imbedded Markov chains allow an analysis when either the interarrival or the service times are exponentially distributed. The general case may be studied using the theory of random walks via Lindley’s equation. Open and closed networks of Markovian queues may be studied via their stationary distributions.
Martingales
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

The general theory of martingales and submartingales has many applications. After an account of the concentration inequality for martingales, the martingale convergence theorem is proved via the upcrossings inequality. Stopping times are studied, and the optional stopping theorem proved. This leads to Wald’s identity and the maximal inequality. The chapter ends with a discussion of backward martingales and continuous-time martingales. Many examples of the use of martingale theory are included.
Diffusion processes
Authors: Grimmett Geoffrey R , Stirzaker David R
Published: November 2023

An elementary description of the Wiener process (Brownian motion) is presented, and used to motivate an account of diffusion processes based on the instantaneous mean and variance. This leads to the forward and backward equations for diffusions. First-passage probabilities of the Wiener process are explored using the reflection principle. Interpretations of absorbing and reflecting barriers for diffusions are presented. There is a brief account of excursions, and of the Brownian bridge. The Itoˆ calculus is summarized, and used to construct a class of diffusions which are martingales. The theory of financial mathematics based on the Wiener process is described, including option pricing and the Black–Scholes formula. Finally, there is a discussion of the links between diffusions, harmonic functions, and potential theory.
Hypothesis testing
Authors: Garthwaite Paul , Jolliffe Ian , Jones Byron
Published: November 2023

The most usual formulation of a hypothesis-testing problem is that we have to decide between two hypotheses regarding one or more parameters θ . The two hypotheses are the null hypothesis, which we denote by H  0: θ ω , and the alternative hypothesis, which we denote by H  1: θ Ω ω . Thus Ω is the set of all possible values for θ , called the parameter space and ω is some subset of Ω.
Interval estimation
Authors: Garthwaite Paul , Jolliffe Ian , Jones Byron
Published: November 2023

In Chapters 2 and 3 we discussed point estimation at some length. However, as was noted in Chapter 1, a point estimate on its own is of little use—some measure of its precision is also necessary. This leads naturally to the idea of interval estimation, which is of great practical importance. Nevertheless, we devote less space in this book to interval estimation than to either point estimation or hypothesis testing. This is because the theory underlying interval estimation is closely related to that already covered for point estimation and hypothesis testing, and the theory is most conveniently developed in these latter contexts. In fact, there is a close relationship between interval estimation and hypothesis testing, so that many of the ideas of hypothesis testing carry over directly to interval estimation; we show this later for some of the more useful ideas. The approach used in most of this chapter is known as the frequentist approach.
Non-parametric and robust inference
Authors: Garthwaite Paul , Jolliffe Ian , Jones Byron
Published: November 2023

In much of inference, for both the frequentist and Bayesian approaches, there is an assumption that we know the form of the p.d.f. f (x ; θ ), apart from the values of one or more parameters θ . In practice, this is often an unrealistic assumption. For example, a distribution may be approximately normal, but it is rarely exactly so. In more extreme cases, we have little confidence that we can correctly specify a parametric form for a p.d.f. This occurs particularly when only a small sample of observations is available, so that the shape of the distribution is not easily estimated.
Genetic diversity in nature: global, regional, and local
Authors: Nevo Eviatar
Published: November 2023

Are the levels of genetic polymorphism in subterranean mammals predictable and adaptive or, alternatively, are they basically stochastic and functionally neutral? The major unresolved problem haunting evolutionary genetics is how much of the genetic diversity at the protein, DNA, and chromosomal levels is adaptive, processed by natural selection, and contributes to differential fitness? Rephrased, what is the relative importance of selective (natural selection) and seemingly non-selective (mutation pressure in the broadest sense, recombination, migration, and genetic drift) factors in genome evolution? This problem relates directly to the levels of genetic polymorphism of subterranean mammals: is homoselection operating in fossorial and subterranean mammals?
Baroreflex anatomy
Authors: Eckberg Dwain L , Sleight Peter
Published: November 2023

During embryonic development, aortic and carotid baroreceptor areas arise from the third and fourth branchial arches (Koch 1931). Neural structures presumed to be baroreceptors are dense in the arch of the aorta between the brachiocephalic artery and the ligamentum arteriosum (Roever 1869; Tello 1924), the carotid sinus (De Castro 1926; Sunder-Plassmann I 930; Koch 1931), and other areas, including the common carotid, subclavian, and innominate arteries (Kahn 1929; Nonidez 1937). Although these latter arteries have innervation, the density of innervation is not as great as that of the carotid sinus area (Shin et al. 1987), and almost all baroreflex control is thought to be exerted by receptors in the carotid sinus and aortic receptor areas (Heymans et al. 1944). The anatomy of arterial baroreceptors has been reviewed in many articles (e.g. De Castro 1940; Ábrahám 1953; S.M. Hilton 1963; Rees 1967b; B. Winter 1972) and books (de Boissezon 1942; W.E. Adams 1958; Grigor’eva 1962; Abraham 1969).
Efferent baroreflex responses
Authors: Eckberg Dwain L , Sleight Peter
Published: November 2023

Human baroreflex studies are based necessarily on the experimental ‘black box’ approach. A major strength of studies conducted with human volunteers—that data can be obtained from intact co-operative subjects without anaesthesia—is also a major weakness. The degree of invasiveness is limited in human studies (however, these limits are being rolled back steadily), and because subjects are intact, much of the information obtained is indirect and inferential. The present chapter focuses on methods available for measuring or estimating efferent neural responses related to baroreceptor activity in humans. Just as Chapters 4 and 5 emphasize that baroreceptor stimuli (input) must be controlled and quantitated precisely, the present chapter emphasizes that efferent responses (output) to changes of baroreceptor activity must also be quantitated accurately. An obvious corollary of this is that when conclusions are based on highly inferential data, the assumptions underlying the inferences must be recognized and dealt with explicitly.
Effector responses to baroreceptor forcings
Authors: Eckberg Dwain L , Sleight Peter
Published: November 2023

With the exception of studies in which sympathetic nerve traffic or levels of plasma neurotransmitters are measured, most human baroreflex research concentrates on effector organ responses to baroreflex forcings. In such studies, the effector organ is at the end of a cascade of changes imposed at earlier stations in the reflex arc. In some instances, effector responses betray changes imposed earlier; certain effector response patterns may offer the only glimpse available into contributions of earlier segments in the human baroreflex arc. For example, sinus node responses must reflect, in some way, characteristics of baroreceptor transduction. It seems likely that proportionality between sinus node responses and induced changes of arterial distending pressure reflects proportionality of baroreceptor responses. An intuitively attractive extrapolation of this is that thresholds and saturations of sigmoid baroreflex response relations measured from electrocardiograms (Eckberg 1980a; Kasting et al. 1987) and muscle sympathetic nerve recordings (Rea and Eckberg 1987) reflect thresholds and saturations of baroreceptor neurones. Similarly, as discussed in Chapter 6, rate sensitivity, adaptation, and resetting seen in sinus node responses must in some way reflect rate sensitivity, adaptation, and resetting of baroreceptors.
Adaptive radiation and macroevolution
Authors: Stanley S M
Published: November 2023

Many adaptive radiations have produced substantial evolutionary changes during relatively brief intervals of time. There is evidence that punctuational speciation events have played an important role in many radiations. Diversification early in adaptive radiation usually approximates exponential increase and can be shown often to have occurred because probability of speciation exceeded probability of extinction. There is a general correlation among taxa in characteristic rate of speciation and rate of extinction during adaptive radiation. This can be attributed to control of both rates by the same causal factors. A few ‘supertaxa’ are characterized by relatively high rates of speciation and low rates of extinction.
Major insect radiations
Authors: Wootton Robin J
Published: November 2023

The principal aspects and events in the evolution of insects, and the nature of their fossil record are reviewed. A Palaeozoic fauna of extinct orders and suborders, diverse in size, habitat, habit, and diet, was progressively replaced in the Permian by the stem-groups and early representatives of extant orders. The distribution in time of the Palaeozoic orders, and the first appearances of super families of most of the remaining orders, are figured and discussed. There is no very strong evidence for explosive supraordinal radiations following significant evolutionary events, and the first appearances of important groups are not always immediately followed by major diversification. Within orders rapid expansions can be recognized following the presumed appearance of new types of larva, and particularly in association with the rise of the angiosperms, which provided the impetus for massive radiations at several trophic levels.
The radiation of post-Palaeozoic echinoderms
Authors: Simms Michael J
Published: November 2023

Of the five extant echinoderm classes at least two, crinoids and echinoids, experienced a decline in diversity in the late Palaeozoic, with only a handful of taxa surviving into the early Triassic, whilst cladistic analysis of the asteroids suggests that they too passed through an evolutionary bottle-neck at this time. Only among echinoids and crinoids is the fossil record sufficiently well documented and representative for their subsequent post-Palaeozoic history to be interpreted. From very low diversity in the early Triassic, both groups diversified rapidly in the mid-Triassic to an early Carnian peak.
Placoderm fishes: diversity through time
Authors: Gardiner B G
Published: November 2023

The placoderms, with 250 genera, constitute a small but much diversified group of bony fishes. They are sometimes classified as stem-group osteichthyans and, together with the acanthodians, are the earliest true jawed fishes. They are found in the mid-Silurian, but flourished in the Devonian reaching their greatest diversity in the late Devonian (Frasnian). Although 13 genera made their first appearance in the Famennian, no placoderm survived into the Carboniferous. The Arthrodira (150 genera) is the largest group, while the coccosteoids are the niost successful clade within the arthrodires. The last major diversification of the arthrodires occurred in the late Famennian with the appearance of the largest of all placoderms. Stratigraphical distributions of placoderm genera are reviewed, and phylogenetic relationships are inferred between the principal groups.
Angiosperm radiation and patterns of Cretaceous palynological diversity
Authors: Crane Peter R , Lidgard Scott
Published: November 2023

Cladistic analyses indicate that angiosperms, Bennettitales, Gnetales, and Pentoxylon together form a monophyletic group, and imply that angiosperms may have diverged from related taxa as early as the Triassic. However, quantitative evaluations of systematic diversity in Cretaceous macrofloras and palynofloras show that angiosperms did not radiate to floristic prominence until the Aptian-Albian.
The causes of the diversification of life
Authors: Benton M J
Published: November 2023

Diversification on the large scale has been explained in many different ways. Equilibrium and non-equilibrium models of various kinds have been proposed, but both kinds suffer from unsupported assumptions. More specific explanations of diversification fall into four main categories: (1) the patterns are artefacts of a biased fossil record; (2) the patterns are real and caused mainly by physical perturbation; (3) the patterns are real and caused mainly by biotic factors; or (4) the patterns are real but stochastic. At least 14 specific explanations have been given, but most of these fail to explain long-term global patterns. Three main candidate models for large-scale diversification are tested with data from the fossil record of tetrapods, and the strongest seems to be expansion of adaptive space, followed by subdivision of niches and specialization, and then by provinciality caused by topographic and climatic change. These tests illustrate some of the complexities of disentangling the different explanations for diversification, but they point to ways in which such tests may be quantified.
Diversification of spores 1n fossil and extant Schizaeaceae
Authors: van Konijnenburg-van Cittert Johannah.A
Published: November 2023

Data from literature on both extant and fossil schizaeaceous spores have been combined with research on spores of 23 extant species and new scanning electron microscopy (SEM) data on several fossil species. In addition to in situ fossil spores, dispersed fossil spores attributed to the Schizaeaceae have been taken into account. In this way some ideas were obtained about the diversification of spores in the Schizaeaceae.
Diversification of early angiosperm pollen in a cladistic context
Authors: Doyle James A , Hotton Carol L
Published: November 2023

Comparisons of early fossil angiosperm pollen types with cladograms of extant angiosperms permit firmer inferences on affinities of fossils and bear on competing hypotheses of relationships among taxa. The shortest trees root angiosperms in or near Magnoliales, implying that granular monosulcate pollen is primitive, but trees rooted among herbaceous magnoliids and monocots (paleoherbs), supported by molecular data, are almost as parsimonious. The five main clades of angiosperms are all represented by the Barremian-Aptian, confirming their status as early lines. Large, granular monosulcates from the Potomac Group (Lethomasites) may represent core Magnoliales.
Patterns of development in primitive angiosperm pollen
Authors: Gabarayev N I
Published: November 2023

Three important aspects of sporoderm ontogeny in pnmIUve angiosperms, belonging to the families Magnoliaceae, Annonaceae, and Nymphaeaceae, are discussed in relation to gymnosperm and angiosperm phylogeny. These are the formation and differentiation of the primexine matrix, the formation of endexine lamellae, and the presence of unusual configurations of endoplasmic reticulum associated with synthesis of sporopollenin precursors. Primexine matrix is considered to provide valuable information concerning the structure of the sporoderm. An endexine is apparently present in all of the eight species studied, and this has consequences for discussion of seed plant relationships.
Diversification and evolution of the tapetum
Authors: Pacini E , Franchi G G
Published: November 2023

Two kinds of tapeta are usually distinguished in angiosperms: the parietal or secretory type, and the amoeboid or periplasmodial type. However, the tapetum is present in all major groups of land plants and exhibits a great range of forms.
Underwater pollination, three-dimensional search, and pollen morphology: predictions from a supercomputer analysis
Authors: Cox Paul Alan , Cromar Scott , Jarvis Tyler
Published: November 2023

Unlike terrestrial plants, which are pollinated by animals or the wind, many marine and freshwater angiosperms are pollinated by water. Yet little has been known of the mechanics of underwater pollination systems. Two-dimensional random search theory, which has been of use in studying two-dimensional hydrophilous pollination on the water surface, has yet to be developed for three dimensions. Numerical experiments of three-dimensional collisions and target encounter rates would be extremely useful in understanding the pollination strategies of underwater-pollinated plants, but the tremendous computational time requires the speed of a supercomputer for calculation purposes.
Nitrogen: agricultural productivity and environmental problems
Authors: Mengel Konrad
Published: November 2023

On a global scale plants play an essential role in the conversion of inorganic into organic nitrogen, which is a basic process in plant growth and crop production. Crop yields depend much on the supply of inorganic nitrogen and are generally increased by the application of nitrogen fertilizers. Without nitrogen fertilization it would be impossible to feed the world’ s population. Of the various fertilizers, nitrogen fertilizers are those which are applied in highest quantities on a global scale. They have a great impact on crop production; nitrogen influences a number of processes which are relevant in determining the quality of plant products, and nitrogen fertilizers also affect ecological processes. In this paper some major aspects of the importance of nitrogen for crop production and its impact on the environment are considered.
Some aspects of the utilization of nitrate and ammonium by plants
Authors: Pilbeam D J , Kirkby E A
Published: November 2023

The two major forms of nitrogen taken up by plants are nitrate and ammonium ions. In most soils nitrate is the more abundant of these ions, although in acid soils ammonium predominates because nitrification is largely inhibited. Most plants, except those adapted to acid conditions, grow better when supplied with nitrate. Although nitrate is usually the preferred nitrogen source for plant growth, the uptake and assimilation of this ion appear to be metabolically more expensive than the uptake and assimilation of ammonium, not least because the nitrate ion is reduced to ammonium after uptake. Raven (1985) has estimated that the metabolic cost to a plant assimilating ammonium is 296 photons per mol nitrogen assimilated, compared with the cheapest way in which nitrate can be assimilated, which is 305 photons per mol nitrogen.
Uptake and assimilation of nitrate under nitrogen limitation
Authors: Larsson C M , Mattsson* M , Duarte P , Samuelson M , Öhlén E , Oscarson* P , Ingemarsson B , Larsson M , Lundborg* T
Published: November 2023

Nitrogen concentrations in plant tissue normally range from 0.5-5 per cent of total plant dry matter, depending on plant species, tissue type, tissue age, and nitrogen availability. Nitrogen reservoirs in soils are, with few exceptions, massive compared to the amount of nitrogen contained in living biomass (Post et al. 1985; Haynes 1986). However, release of nitrogen in mineralization may be slow, and its availability to individual plants further limited by factors affecting its mobility, by intra- and interspecific competition, or by denitrification. Thus, nitrogen availability may be a major factor limiting plant productivity in natural stands. Likewise, nitrogen input is required in agriculture to compensate for output (harvest, gaseous losses, runoff, and leaching) and may often be yield-limiting (detailed reviews of these subjects are available in Haynes, 1986).
Amino acid transport across the higher plant cell membrane
Authors: Bentrup Friedrich-Wilhelm , Hoffmann Bernd
Published: November 2023

This chapter first briefly outlines current aspects and problems of amino acid transport in the higher plant. Secondly, we present novel data from a photo autotrophic suspension cell culture which demonstrates the operation of an amino acid exchange carrier in the plasmalemma by efflux analysis. In higher plants, a flow of amino acids passes from the key site of amino acid synthesis in the photosynthetically active tissues to the heterotrophically growing meristematic and storage tissues of stem, fruits, and roots. Photo synthates in the phloem, including amino acids, cross the plasmalemma several times if passing through the apoplast while en route from the source mesophyll to sink tissues. Thus the plasmalemma is an established site for the recognition and specific transport of pertinent substrates, and is a plausible site of physiological control of the overall translocation process.
Ammonia assimilation in higher plants
Authors: Lea Peter J , Blackwell Raymond D , Joy* Kenneth W
Published: November 2023

Since 1974, the pathway of the assimilation of ammonia in higher plants has been considered to be via the combined action of glutamine synthetase and glutamate synthase, as shown in Fig 11.1. The pathway has been termed the glutamate synthase cycle by Rhodes et al. (1980), and there have been numerous review articles discussing the operation of the cycle (Miflin and Lea 1980; Miflin and Lea 1982; Joy 1988; Lea et al. 1990b). The reactions of the pathway are outlined below.
Environmentally induced adaptive mechanisms of plant amino acid metabolism
Authors: Pahlich E
Published: November 2023

The basic pathways and interactions in plant metabolism have been uncovered, and this knowledge condensed in metabolic maps: these maps inform, at a qualitative level, which reactions occur, how pathways are composed, where ramifications exist, and which regulatory loops are operative. They answer the question ‘ what is’. Unfortunately, these maps cannot inform us about actual fluxes, and their adaptation to a changing external and internal environment of cells. They provide no help in answering the question ‘ how much’ of a transformation occurs under given circumstances and ‘ why’ a respective flow rate is established under these conditions. These questions can be answered only with the help of the quantitative concepts of control of biochemical pathways which have been available since the early seventies (Kaeser and Burns 1973; Heinrich and Rapoport 1974). From the quantitative concepts, it is apparent that the properties of metabolic pathway systems are characterized by (mainly genetically determined) sets of parameters (kinetic and thermodynamic constants) which specify the pools of the pathway variables (contents of metabolites) and the intensities of the respective fluxes. Only the changes of the parameters change the system’ s character.
Barley seed storage proteins- structure, synthesis, and deposition
Authors: Shewry P R
Published: November 2023

Cereals are the most important crops in the world, with total annual yields approaching 2 x 109 tonnes. Proteins account for about 8 to 15 per cent of the grain dry weight, and the total protein yield exceeds by several-fold that of the more protein-rich legume seeds. They therefore form the major source of protein for the nutrition of humans and lifestock. Wheat is the most important cereal in Europe (as it is in the world as a whole), and barley the second most important. In both cases the amount and composition of the grain storage proteins, which account for about half of the total grain proteins, have important effects on the quality of the grain for its major end uses: as feed for mono-gastric livestock, for bread-making and for malting, brewing and distilling.
Polyamine metabolism and compartmentation in plant cells
Authors: Bagni Nello , Pistocchi Rossella
Published: November 2023

Polyamines are ubiquitous nitrogenous compounds classified as plant growth substances (Bagni 1989). They act mainly in processes based on cell division, with a broad spectrum of effects on various plant tissues, but very little is known about the basic mechanisms and events of this action. Studies on the role of polyamines are complicated by the lack of plant mutants deficient in polyamines. Additional knowledge of their action can be obtained by studying in greater detail their biosynthetic pathways, as well as by blocking them at various steps by using the various inhibitors now available. The study of their transport and compartmentation could also help to explain some effects, such as the different sensitivity of a plant tissue or organ to applied polyamines and the different rate of polyamine synthesis within the same plant, besides providing information on the nature of polyamine action.
Distribution and biological activity of alkaloidal glycosidase inhibitors from plants
Authors: Fellows Linda E , Kite Geoffrey C , Nash Robert J , Simmonds Monique S J , Scofield* Anthony M
Published: November 2023

Alkaloidal glycosidase inhibitors (AG Is), which have been reported to occur in many species of higher plants, bacteria and fungi, are probably widespread in nature. They belong to five different chemical structural types, namely polyhydroxylated derivatives of piperidine, pyrrolidine, pyrroline, octahydroindolizine, and pyrrolizidine. Certain of the simpler piperidine and pyrrolidine derivatives bear an obvious structural resemblance to 1-deoxy monosaccharides, with the ring oxygen replaced by nitrogen. The orientation of hydroxy groups on the more complex bicyclic structures also suggests a structural resemblance to sugars. AG Is exhibit a range of different types of biological activity. The structures of all AG Is described to date are shown in Figs 16.1-16.3 For simplicity compounds will be referred to by their common names or abbreviations, if any, in this chapter.
How important is grazing to seaweed evolution and assemblage structure in the north-east Pacific?
Authors: Foster Michael S
Published: November 2023

Numerous studies have shown that grazing by large invertebrates can be important in shaping seaweed assemblage structure, and that such grazing may have been important to macroalgal evolution. The questions of how important this interaction is to assemblage structure along the temperate shores of the north-east Pacific, and how important it may have been to evolution in this geographic region are reviewed. The reported effects of grazing on foliose algal cover at spatial scales from geographic to small patches suggest that grazing is generally (at most of the sites studied) important only in high intertidal-splash zone assem blages, where limpets, littorines, and other herbivores prevent the establishment of most seaweeds. While sea urchins can greatly reduce the cover of foliose plants in subtidal assemblages, this effect is highly variable in space and time. The importance of grazing to patch structure at scales of centimetres to metres is potentially high but remains largely unexplored. While grazers may have large effects in cleared areas during the early stages of intertidal succession, these effects are short-lived and grazer densities are only weakly correlated with recovery rate.
A trophodynamic model of fish production on a windward reef tract
Authors: Polunin N V C , Klumpp D W
Published: November 2023

The biological basis of fish-biomass production on coral reefs has not been explored, but in this paper a trophodynamic model is constructed for the first time. Previously published data on benthic primary productivity, rates of macrograzing and planktivory, and abundances of mesofauna of a windward reef-tract at Davies Reef, Great Barrier Reef, Australia are synthesized to provide a view of the dominant sources and immediate fates of organic carbon in this system. These fluxes are postulated to support fish production primarily through eight different types of food-chain (five algal-based and three plankton-based) which vary in numbers of links and the food-chain efficiencies postulated for them. Fish production is estimated by making extra assumptions about the level of meso-grazing and calculating detritus production by difference. Using the model, the potential fishery yield of macro-grazers over the whole reef is 4 t km-2, invertebrate-feeders 7-16 t km-2, piscivores 0-2 t km-2 and of planktivores 3 t km-2. Maximum predicted yield is 14-23 t km-2 for a fishery targeted at macrograzing, invertebrate-feeding, and planktivorous fishes, which in carbon terms is 0·5-0·8 per cent of gross primary productivity or 1·1-1·9 per cent of net primary productivity (NPP). If the predicted fish production were realized, this coral reef would have as high a fish yield in relation to its primary productivity as other productive marine ecosystems.
Foraging behaviour of marine benthic grazers
Authors: Chapman M G , Underwood A J
Published: November 2023

Benthic grazers exhibit a variety of different patterns of foraging. These vary among habitats and among taxonomic groups. Broadly, foraging behaviour has two components: firstly, the behaviour that brings animals into contact with their plant foods; secondly, the animals respond to the presence of food in different ways. Each can be affected by different physical or biological conditions. Here, foraging behaviour is examined in order to evaluate the evidence upon which our understanding of this behaviour is based. The roles of physical factors (such as shelter) and biological interactions (such as competition and predation) are considered. These are discussed in the light of some general models to account for foraging by different animals and with a view to outlining hypotheses of interest for further study.
Chemical mediation of seaweed-herbivore interactions
Authors: Hay Mark E , Fenical William
Published: November 2023

Seaweeds produce a variety of secondary metabolites that deter feeding by herbivores. The defensive value of a compound is, however, a specific function of the compound’s structure and the species of herbivore attacking the plant; previous generalizations about the effectiveness and mode of action of different classes of compounds (e.g., qualitative vs quantitative chemical defences) are unfounded.
Digestion survival in seaweeds: an overview
Authors: Santelices B
Published: November 2023

Several types of seaweeds survive passage through the digestive tract of various types of grazers.