bluuebunny/crossref_metadata_2025 huggingface dataset:
Ngf Family Of Neurotrophins And Their Receptors: Early Involvement In The Progression Of Alzheimer‘s Disease
Authors: Mufson Elliott J , Counts Scott E , Fahnestock, Margaret , Ginsberg Stephen D
Published: November 2023

Cholinergic basal forebrain (CBF) neurons of the nucleus basalis (NB) provide the major cholinergic innervation to the cortical mantle, are selectively vulnerable in late-stage Alzheimer‘s disease (AD), and require the neurotrophin nerve growth factor (NGF) for survival. The neurobiological events underlying the eventual demise of NB neurons during the progression of AD remain unknown. Our group investigated the molecular events underlying the degeneration of cholinotrophic basal forebrain neurons in tissue harvested from subjects participating in a longitudinal clinical pathological study of ageing and AD.
Clinical Assessment Of Alzheimer‘s Disease
Authors: Bhattacharyya Sarmishtha , Overshott, Ross , Burns Alistair
Published: November 2023

In the past the symptoms of dementia were often dismissed as an inevitable accompaniment of advanced age. With raised public awareness of dementia, and the development of memory clinics, patients and doctors are now less likely to accept cognitive impairment as ‘just old age ‘. Patients and their carers are increasingly requesting assessment in the hope that they can receive a diagnosis and treatment.
Recurrent Viruses and Theories Of Sexऻ
Authors: Hamilton W D
Published: November 2023

The review by Lin Chao1 on sex in RNA viruses presents a balanced view of the merits of what may be called the ‘positive eugenical ’ and ‘negative eugenical ’ theories of sex as applied to these viruses. Judging between these I share his preference for the negative, both on his specific viral arguments and in general. However, his survey steps across an intermediate yet fairly distinct theory which I think has stronger evidence than either extreme.2 In discussing the influenza virus he comes close to, but doesn ’t mention, some good evidence for this theory.
On First Looking Into A British Treasurey
Authors: Hamilton W D
Published: November 2023

When I was a boy, Britain was way ahead of the rest of the world in the publishing of books on natural history—indeed until quite recently colleagues from America, Eastern Europe and Japan would gasp at the wealth of our productions and wish they had something similar: the pages and pages of coloured plates of set butterflies and moths, of beetles, bugs, painted toadstools, and the colour-illustrated ﬂoras that soon covered not only Britain but also Northern Europe.
How to catch the red queen?
Authors: Ebert Dieter
Published: November 2023

In 1980 Bill Hamilton published a paper with the attention-getting title ‘Sex versus non-sex versus parasite ‘, in which he proposed that parasitic diseases are an important factor for the maintenance of sexual reproduction. This hypothesis came to be known as the Red Queen hypothesis because it is based on the idea that hosts and parasites are in a never-ending race, just as the Red Queen in Lewis Carroll ’s fairy tale cannot stop running, or else she would lose her position. Although the Red Queen hypothesis attracted a lot of attention, more than ten years after it was proposed very little empirical work had yet been conducted on it. Surprisingly, the widespread support that the hypothesis had earned by the early 1990s among many evolutionary ecologists was not based on hard data, but on its plausibility and the increasing recognition that parasites are indeed everywhere.
A View From Mars
Authors: Brown Sam P
Published: November 2023

By the time I encountered the name W. D. Hamilton, I had already abandoned the science of biology as being impossibly dull. As an idle second-year philosophy student, I chanced upon a dog-eared copy of Dawkins ‘ The Selfish Gene on a friend ’s bookshelf. This book knocked my socks off. I was filled with wonder at the forces of evolution, and the force of Bill ’s ideas. Bill ’s memes certainly had a dramatic effect on my behaviour. With near missionary zeal I at last experienced a sense of calling beyond the college bar. Within weeks I was even pleading to be re-admitted to the biology programme I had so gleefully escaped only a year before. Bill had been a biology undergraduate in Cambridge 30 years before me, and had not been enamoured with the prevalent disregard for evolutionary analyses.
Shapes and numbers
Authors: Bradley Christopher J
Published: November 2023

The ‘numbers’ in the title of this chapter are actually integers, but the title is determined by the fact that well-known names for what we consider here are such things as triangular numbers, polygonal numbers, and polyhedral numbers. In this chapter we try to provide material that is either new or less well known, rather than provide what tends to be given in books on recreational mathematics. We start by considering the triangular numbers in some detail, highlighting their connection with the squares, and in particular dealing with the representation of positive integers as the sum of triangular numbers. In doing this we draw attention to the connections that exist between theorems on triangular numbers and square numbers. We point out that any primitive Pythagorean triplet also has its analogue amongst the triangular numbers. We then describe other shapes and the numbers associated with them. Next we consider the problem of determining which polygonal numbers are also square numbers or triangular numbers. For some polygonal numbers only a FB01nite number of them are squares, but for others there are an inFB01nite number. The Pell equation once again features in this problem. Finally, we give a brief account of the Catalan numbers.
Touching Circles and spheres
Authors: Bradley Christopher J
Published: November 2023

It has been known for a long time, see Pedoe (1970), that the curvatures of four mutually touching circles are related by a single straightforward equation. The result was FB01rst obtained by Descartes (1901). In this chapter we show that inFB01nite chains of touching circles, all with integer curvatures, can be formed. This means that the circles involved all have rational radii. Furthermore, we show how to obtain all such chains. In the FB01rst section we deal with the singular case when one of the circles degenerates into a line. In the next section we deal with the case of sequences of mutually touching circles in two dimensions. We then go on to show how to generalise to sequences of mutually touching spheres in three dimensions, and FB01nally to mutually touching hyperspheres in four dimensions. InFB01nite chains exist in all of these cases, and recurrence relations are established to show how they are formed.
Strange and chaotic attractors
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

In the early 1970s, mathematicians David Ruelle and Floris Takens introduced the concept of the strange attractor to describe the phenomenon of turbulence (Ruelle and Takens, 1971; see also Ruelle, 1991). A strange attractor is a subset of points in the phase space that is fundamentally different to that of the objects belonging to ordinary Euclidean geometry; it is a geometric object characterized by a dimension that is not an integer number. The French mathematician of Polish origin Benoit Mandelbrot, also in the 1970s, coined the expression ‘fractal’ to indicate geometric objects whose dimension is not integer (Mandelbrot, 1975): strange attractors are fractal objects.
Modelling
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

During our entire lives we learn to construct mental models of the world that surrounds us. Catching a falling object by anticipating where it is going to fall before it gets there, understanding the thoughts of an interlocutor before he speaks on the basis of a few signs, deciphering the intentions of an opponent before he acts; these are just a few examples of how we read a situation and its various aspects, something that we all do constantly, constructing models based on our store of previous experiences as well as our attempts or mistakes. As we said in Chapter 1, in science, the study of systems that evolve over time, i.e. of systems whose state changes over time, is particularly interesting. The swinging of a pendulum, the radioactive decay of a substance, the movement of the planets in the solar system, the growth of a plant, the trend in the number of individuals of a particular population in a defined territory, the flow of road traffic along a street or that of telephone communications in a channel and the trend of a stock exchange index, are just some examples of what we mean by a system that evolves over time. In each of the above examples, as in many others, we have a set of states at various points in time and we seek a law of motion that reproduces the succession of these states over time. A large part of scientific work, from the very origins of science onwards, has concentrated on establishing the ‘right’ law of motion to describe the evolution of a system over time, based on observations of a limited set of successive states (Casti, 2000). When these activities lead to the formulation of recurrences (laws) in a mathematical language, then we have a mathematical model.
Linearity as a first, often insufficient approximation
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

The perception that we have of reality and, in particular, of the dynamic processes that we observe therein, is such that rarely, if at all, do we witness a direct and strict proportionality between ca use and effect (in more specific contexts, other expressions could be used, such as proportionality between input and output, between stimulus and response, between action and reaction, and more besides). In fact, at times actions of relatively small intensities produce consequences that appear to be disproportionately large with respect to the size of the action, or, vice versa, actions that we consider to have a large intensity have unexpectedly little effect with respect to our expectations. Situations of this nature are very frequent and typical to our perception of reality.
The nonlinearity of natural processes: the case of the pendulum
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

A closer analysis of the dynamics of the pendulum, still starting from Newton’s law, leads to a different formulation of the equation of motion, less rough in its approximation and more articulated in its details.
Nonlinear models in social processes: the Volterra-Lotka model applied to urban and regional science
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

As we mentioned at the beginning of Chapter 12, several variants of the Volterra-Lotka model have been used to model urban and regional systems. The dynamics obtained generally lead back to those obtained with the ecological models iJlustrated in Chapter 12. Nevertheless, it is evident that ecological models can only be applied through homologies, i.e. purely formal equivalences conducted between the biological sphere and that of urban and regional science; meanings relating to other scientific sectors can under no circumstance be strictly attributed to the magnitudes typical of urban and regional science.
Dynamical systems and chaos
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

Before proceeding, we would like to remind readers of a concept that was stated in Chapter 8: by dynamical system we simply mean a system of equations that define the evolution of a set of state variables in discrete or continuous time. It is therefore important not to confuse the abstract mathematical concept of dynamical system, with that of system, which for the sake of clarity we will call real, and which instead refers to the empirical observation of phenomena and to the measurement of series of data. The mathematical models we are examining are written in the form of dynamical systems: therefore the properties of the models that we wil1 be discussing should be considered properties of dynamical systems.
Stability in dynamical systems
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

As a mathematical model in the form of a dynamical system evolves, it generates a sequence (sets) of numbers that represent states in a phase space, i.e. an orbit; the meaning that is attributed to these (sets of) numbers depends on different factors, as we have discussed on several previous occasions. Of these, we have the problem of sensitivity to (small) changes in the initial conditions, that is to say the study of ‘by how much’ said changes influence (‘propagate’) the numerical values calculated for future states, provoking large or small variations of the same. The stability characteristics of the orbit have to be analysed, which requires, first and foremost, a definition of stability and a method to quantify it. We will be examining this in this section.
A nonlinear discrete model: the logistic map
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

In this section we want to continue our discussion of the growth model presented in Chapter 20, the logistic law, illustrating the dynamics of the version in discrete time (20.4). We are particularly interested in showing how a simple nonlinear growth model such as (20.4), that determines the logistic growth of a population, can in some cases generate chaos. In Chapter 22 we will be illustrating various examples produced by means of numerical simulations, as well as some applications of the logistic map in regional sciences. Readers interested in a complete description of the properties of the dynamics of the logistics map can find detailed and in-depth discussions of the mathematical aspects, which in this text are only briefly mentioned, in two fundamental articles. These are works that have reproposed the logistic map to scholars in recent decades, more than a century after Verhulst introduced it: the work of Robert May (1976), the first, in recent years to examine the properties of the map, and that of Mitchell Feigenbaum (1978), whose content is more technical, in which specific aspects are looked at in more depth and generalized.
Some aspects of the classical vision of science
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

Before actually going into the merits of complexity, we would like to define a framework, albeit partial, of the scientific thought in the eras, prior to modern times, in which the concept of complexity was developed. Let us return to astronomy. In the long history of attempts that man has made to formulate predictions for the future, a crucial moment, as we know, was Newton’s discovery that the motion of the planets could be described by a particular type of equation, differential equations, that he himself invented, which, therefore, became the main tool, if not the only one, that enabled scientists to look into the future. From astronomy and, in particular, from the successes achieved in celestial mechanics based on Newton’s brilliant intuitions (1687), dassical science, and more specifically mathematical physics that originated from celestial mechanics, started their extraordinary development.
From determinism to complexity: selforganization, a new understanding of system dynamics
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

According to Newtonian theory, as we know, space is assumed to be an absolute entity and time a magnitude independent of the former and reversib]e. All of the processes described within the Newtonian framework are reversible. In other words, there is no way of distinguishing between the motion of a body subjected to the action of a force and that of the same body subjected to a force opposite to the previous one, but with time that goes backwards; both appear to be natural. As we know, this schema is completely based on the concept of space provided by Euclidean geometry; it was accepted, used and deve]oped for over a century, after Newton created it, and became one of the distinguishing elements of Kantian philosophy.
What is complexity?
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

Over the past 30 years, there has been considerable progress in studies and research in a number of separate areas that are, however, united by the expression ‘complexity science’. Said research work has led to the development of useful techniques and has generated significant and explicative metaphors. However, to date, the work conducted in this field has not been founded on a coherent ‘complexity theory’ even though it is a commonly used expression (even we will be using it in the following sections), nor has it been formalized into a system of axioms and theorems that can be generally applied across the various disciplines. Our further investigation of the subject of complexity will not be based on an abstract view of the latter; we will be looking more at how it manifests itself.
Complexity and evolution
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

In this chapter we will be presenting several applications of the ideas proposed by the new approach of complexity to the evolution of systems, focusing particularly on biological systems and on the appearance of life following a spontaneous process of self-organization. Is there is a general tendency for complexity to increase as a system evolves, just like, in a closed system, there is a tendency of the entropy to increase? This question assumes particular importance, for example, in biology, regarding the evolution of living species, but not only this. The evolution of a complex system is spontaneous, whether it is a natural system, like a galaxy, a planetary system, a biological organism, a crystal, a liquid or a real gas in which the interactions between molecules, etc. are not negligible, or whether it is a social system, such as a human population, an economic aggregate or a language (intended in the strict sense, as a complex of phonemes, words, rules of syntax, etc.). Systems are usual1y assumed to evolve over time towards an increase in complexity, but little or nothing is known of the mechanism that could cause the evolution in that direction, rather than towards a simplification or a reduction in complexity.
Complexity in economic processes
Authors: Bertuglia Cristoforo Sergio , Vaio Franco
Published: November 2023

In this section, we will continue to look at how the approach of complexity has been applied, presenting several examples of models of economic processes constructed according to this new vision of systems. Economics, in fact, is actually one of the fields of research in which the concepts of instability, chaos, and complexity that we have discussed in this book, can best be applied, and it is one of the areas that has most attracted the attention of scholars who have adopted the new concepts proposed by complexity science (see, for example, Barkley Rosser, 1991; Brock, Hsieh and Le Baron, 1991; Benhabib, 1992; Nijkamp and Reggiani, 1993, 1998; Krugman, 1996; Thiel, 1998; Batten, 2000a).
Model selection
Authors: Sivia D S
Published: November 2023

So far, we have been concerned with the problem of parameter estimation. In studying the linear relationship between two quantities, for example, we discussed how to infer the gradient and intercept of the associated straight line. Often, however, there is a question as to whether a quadratic, or even cubic, function might be more appropriate. In this chapter, we go on to consider such cases when there is uncertainty as to which one of a set of alternative models is most suitable.
The causes of cancer
Authors: Allen Naomi , Newton Robert , Gonzalez Amy Berrington de , Green Jane , Banks, Emily , Key Timothy J
Published: November 2023

In the year 2000, cancer was diagnosed in 10 million people worldwide and caused 6.2 million deaths, an increase of about 22% since 1990 (Ferlay et al. 2001). Cancer causes 10% of all deaths worldwide and is second only to cardiovascular disease as the main cause of death in developed countries. Although cancer is usually regarded as a problem of the developed world, about two-thirds of all cancer occurs in the three-quarters of the world’s population who live in developing countries.
From transcriptome to proteome
Authors: Debernardi Silvana , Craven Rachel A , Young Bryan D , Banks Rosamonde E
Published: November 2023

The rapid advance of the Human Genome Project is leading to the identification of the 30,000–35,000 genes that make up our genetic complement. The combination of this sequence information and associated bioinformatic tools together with technological advances in both nucleic acid-based microarray technology and proteomic technologies has opened up the possibility of highly parallel and complementary approaches to investigations of the cancer cell.
Groups
Authors: Cameron Peter J
Published: November 2023

Groups resemble rings in many ways. The main diﬀerence is that the conditions deﬁning a group are less stringent (only one operation and four axioms, half as many as for rings), so that examples of groups are more numerous and varied. But also, there is no ‘canonical example’ of a group, corresponding to the ring Z, on which to base our deﬁnitions and test our intuition.
Comparative genomics of Plasmodium species
Authors: Carlton Jane M
Published: November 2023

The field of comparative genomics of malaria parasites has recently blossomed with the completion of the whole genome sequence of the human malaria parasite Plasmodium falciparum and three species of rodent malaria model. With several more genome sequencing projects of primate, human, and bird Plasmodium species close to completion, comparing genomes from multiple Plasmodium species promises to provide a wealth of new data that can be used to develop a better understanding of the biology of the parasite.
Hypnosis And The Unity Of Consciousness
Authors: Bayne Tim
Published: November 2023

Hypnosis appears to generate unusual—and sometimes even astonishing—changes in the contents of consciousness. Hypnotic subjects report perceiving things that are not there, they report not perceiving things that are there, and they report unusual alterations in the phenomenology of agency. In addition to apparent alterations in the contents of consciousness, hypnosis also appears to involve alterations in the structure of consciousness. According to many theorists—most notably Hilgard—hypnosis demonstrates that the unity of consciousness is an illusion (Hilgard 1977).
Lagrangian formalism and field theory
Authors: Dunajski Maciej
Published: November 2023

Our treatment of integrable systems in the first three chapters made essential use of the Hamiltonian formalism both in finite and infinite dimensional settings. In the next two chapters we shall concentrate on classical field theory, where the covariant formulation requires the Lagrangian formalism. It is assumed that the reader has covered the Lagrangian treatment of classical mechanics and classical field theory at the basic level [102, 187]. The aim of this chapter is not to provide a crash course in these subjects, but rather to introduce less standard aspects.
Examples Of Stochastic Differential Equations
Authors: Field Timothy R
Published: November 2023

We begin the chapter with some general remarks concerning the physical motivation for the application of stochastic differential equation (SDE) theory to problems in the mathematical description of scattering from random media. Such scattering problems are characterized by two essential ingredients. First, the existence of a random population, whose size fluctuates in time. A measure of the size of this population (in the continuum limit) is what is referred to as the scattering cross-section and its statistical characteristics are independent of those of any external electromagnetic radiation that might be used to indirectly probe the properties of the population. From an experimental point of view, the cross section is usually the object of primary interest and various experiments are designed to infer its behaviour from the properties of electromagnetic radiation that scatters from or propagates through the random medium.
Experimental Tests
Authors: Field Timothy R
Published: November 2023

In this chapter we study two independent examples of data gathered from electromagnetic scattering from random media. The first example involves scattering from a uniform randomizing optical phase screen, which is applied as a calibration tool for the intensity volatility in our diffusive model of K-distributed noise. The second example consists of ocean surface radar scattering data that contains K-distributed sea clutter, a multitude of ‘clutter spike’ anomalies, and a genuine target for which our methodology is used to isolate the anomaly with respect to range.
Descriptive statistics
Authors: Gelman Andrew , Nolan Deborah
Published: November 2023

Descriptive statistics is the typical starting point for a statistics course, and it can be tricky to teach because the material is more difficult than it first appears. We end up spending more class time on the topics of data displays and transformations, in comparison to topics such as the mean, median, and standard deviation that are covered more easily in the textbook and homework assignments. Data displays and transformations must be covered carefully, since students are not always clear on what exactly is to be learned. In presenting the activities in this chapter, we focus on specific tasks and topics to be learned. Also, as always, the activities are designed to be thought-provoking and relate in some way to the world outside the textbook.
Multiple regression and nonlinear models
Authors: Gelman Andrew , Nolan Deborah
Published: November 2023

Near the end of the semester, we cover multiple regression, linking statistical inference to general topics such as lurking variables that arose early in the course. Many examples can be used to illustrate multiple regression, but we have found it useful to come to class prepared with a specific: example, with computer output (since our students learn to run the regressions on the computer). Section 9.1 steps through a continuation of the study of height and income from Section 4.1.2. In Section 9.2 we discuss how to involve the class in models of exam scores. It is also a good strategy to simply find a regression analysis from some published source (for example, a social science journal) and go through the model and its interpretation with the class, asking the students how the regression results would have to differ in order for the study’s conclusions to change.
How to do it
Authors: Gelman Andrew , Nolan Deborah
Published: November 2023

In this chapter we give some tips on how to prepare your own activities and how to adapt an activity you have read or heard about to your particular class. We also provide examples of mistakes we have made in carrying out activities, ideas for managing group work in class and in longer projects, and resources for finding and developing new activities.
Problems and projects in probability
Authors: Gelman Andrew , Nolan Deborah
Published: November 2023

When probability is taught as a separate unit, not as part of a statistics course, then it makes sense to include exercises and examples that are motivated from mathematics rather than from applications. This chapter illustrates one way to promote active student involvement in a more advanced class. The material is designed to accommodate various mathematical backgrounds and to challenge all students.
Evolutionary problems and global solutions
Authors: Nevo Eviatar
Published: November 2023

Some of the foregoing challenges, controversies, and paradoxes of evolutionary biology can be tested and resolved by analysing global, regional, and local experiments of convergent evolution originating due to shared ecological stresses on unrelated taxa. One of the most dramatic experiments of convergent evolution in nature is the evolution of subterranean mammals across the planet (Fig. 2.1, colour figure section). This global experiment originated mainly in Oligocene times, following drastic Eocene—Oligocene climatic changes of aridization, causing remarkable biotic evolution (Prothero and Berggren, 1992). These have driven representatives of several mammalian orders and families to partial or total life in the underground adaptive zone (Van Valen, 1971), a process that continued later throughout Neogene times. Currently, subterranean mammals involve three orders (marsupials, insectivores, and rodents), or four orders if the order Insectivora is partitioned on molecular grounds and the two African families (golden moles and tenrecs) are placed in a new order. The African superordinal clade now includes six orders of placental mammals (Stanhope et al., 1998; De Jong, 1998); 11 families; and at least 250 species (Nevo, 1979, 1995d), but probably many more based on the new evidence of molecular biology, chromosomal evolution, and behavioural ecology (e.g. Nevo, 1991). The stressful life underground resulted in diverse adaptive strategies to cope with the unique physical and biotic environmental conditions of the subterranean ecotope (Dubost, 1968; Pearson, 1959; Nevo, 1979, 1991, 1995d; Nevo and Reig, 1990). Convergent evolution in subterranean mammals intimately coupled regressive evolution of molecular, genetic, morphological, physiological, and behavioural characters with distinct parallel progressive evolutionary phenomena in all the above organizational levels.
Biota evolution in the Cenozoic
Authors: Nevo Eviatar
Published: November 2023

A major parallelism in marine biotic turnover, caused by progressive intensification of cooling near the middle-late Eocene, is seen in all marine groups, both microfossils (phytoplankton, zooplankton and benthic microfauna) and macrofossils (invertebrates and marine vertebrates) (see several papers and controversial explanatory models in Prothero and Berggren, 1992). For example, the largest turnover in planktonic for aminifera affecting most of the older Eocene tropical and equatorial surface groups, a gradual extinction over 80% during 14 million years, occurred near the middle-late Eocene boundary, with 33 biotic turnover events, 18 extinctions, and 33 originations (Aubry in Prothero and Berggren, 1992). Sequential, stepwise extinction pattern during the mid-Eocene to Oligocene characterizes benthic foraminifera (Thomas in Prothero and Berggren, 1992). In gastropods and bivalves of the Gulf Coast of North America, there was a middle Eocene peak of diversity followed by a severe extinction (84 and 89%, respectively) of warm-water molluscs at the end of the middle Eocene (Hansen, 1987). In echinoids, the biggest extinction, correlated with temperature decline, was at the Terminal Eocene Event, when over 50% of the species became extinct (McKin ney et al., in Prothero and Berggren, 1992). Fish diversity, at least in some families, also declined during the middle or late Eocene (Raup and Sepkoski, 1986) but whale diversity increased dramatically by the late Eocene, possibly due to
Rodents: herbivorous subterranean mammals
Authors: Nevo Eviatar
Published: November 2023

The pocket gophers, Geomyidae, are endemic, North American, subterranean rodents (see Wood, 1959, for a discussion on rodent classification) adapted to life underground (Hill, 1937) and located predominantly in western, central, and southern North America (Figs 2.1, 7.1, 7.2 colour figure section). Their skull and external form are modified for subterranean life (Fig. 9.1). They currently involve nine genera (Merriam, 1895); eight genera and 40 species (Anderson, S. 1966), or, in later revisions, six genera and 35 species (Hall, 1981; Thaeler, 1980) or five genera and 36 species (Patton, 1993a). Specific boundaries within all pocket gopher genera are often difficult to define because of an apparent inability to subdivide the subterranean ecotope and thus resultant allopatric distribution patterns (see Patton, 1990a, 1993a,b). These estimates are debatable (e.g. Honeycutt and Williams, 1982), and new, geographically isolated taxa were recently described on molecular, karyotypic, and morphological differences (e.g. Smolen et al., 1993; Wilkins, 1984).
Statistical analyses
Authors: Nevo Eviatar
Published: November 2023

Univariate and multivariate statistics were conducted utilizing the SPSS (1991) and HUDAP (1997) packages. The analyses involved 63 variables (see detailed variables below) categorized into ecological (17 variables; one ecological variable that appears in the Questionnaire, Nest depth was excluded from the analysis because of very scarce data); genetic (5), morphological (14); physiological (4); 2 additional variables, heart rate and breathing rate, that appear in the Questionnaire, Appendix 3, were excluded from the analysis because of very scarce data); behavioural (6); demographic (9); and life history (7). The data set appears in Appendix 2 (ecological and genetics); 3 (morphology and physiology) and 4 (behaviour, demography and life history).
Conclusions and prospects
Authors: Nevo Eviatar
Published: November 2023

The extensive convergent evolution of subterranean mammals across the planet began during the global climatic transition from the middle Eocene to the early Oligocene. It involved cooling, drought, and seasonality stresses proceeding progressively throughout the Cenozoic. The ecological theatre of open country biota set the stage for a rapid evolutionary play of recurrent adaptive radiations of unrelated mammals on all continents to the subterranean ecotope. These comprise marsupial and placental mammals (both insectivores and herbivores), involving hundreds of small mammalian species belonging at present to 50 genera, 11 families, and three (or four) mammalian orders.
Peripheral chemoreceptor function in the fetus and neonate
Authors: Daly M de Burgh
Published: November 2023

The pattern of breathing movements in utero is described together with the role of the peripheral arterial chemoreceptors. In the near-term sheep fetus the carotid and aortic chemoreceptors are active and probably represent the main groups of peripheral arterial chemoreceptors in the primary defence in blood gas homeostasis by their effects on the circulation. The reflex vascular effects include constriction in the limbs. Since the control of the umbilical circulation is largely passive, the flow being dependent almost entirely on the level of the arterial blood pressure, the chemoreceptors in conditions such as arterial hypoxaemia help to maintain blood pressure reflexly and hence umbilical blood flow. The control of the cardiovascular system by the carotid and aortic bodies in the early neonate is complicated by the gradual resetting of the hypoxic sensitivity of the carotid and aortic bodies from the fetal range (normal fetal PaO2 of about 24 mmHg) to the adult range (PaO2 about 80 mmHg) that occurs within the first few days of birth, and by the gradual maturation of the respiratory system.
General conclusions
Authors: Daly M de Burgh
Published: November 2023

The control of the cardiovascular system by the peripheral arterial chemoreceptors is the result of a complex series of integrative mechanisms between, on the one hand, the input from the chemoreceptors themselves and, on the other, a number of inputs from other cardiovascular receptors, activity of the brainstem defence areas, inputs from visceral receptors (such as the urinary bladder), and secondary mechanisms arising from the concomitant changes in pulmonary ventilation (central inspiratory drive, activity of slowly adapting pulmonary stretch receptors, and changes in PaC02). One consequence of these various mechanisms is that the contribution of the chemoreceptors tends to differ quantitatively in different conditions depending on the changes in magnitude of the many individual inputs. Another is that there are species differences in the respiratory responses to any given input from the arterial chemoreceptors, or level of hypoxaemia, being greater in the dog and monkey than cat, rabbit, or rat, which in turn are greater than in the seal.
Relationships
Authors: Nelson J Bryan , Mackay Andrew , Busby John
Published: November 2023

‘To regard nomenclature as more than a means to an end is pedantry and to take a minority course in a matter of convention is merely a nuisance.’ (Thomson 1964) ‘To be confronted with an avian humerus nearly two feet long and distinguish it by a name that means simply “Miocene Seabird” requires an unenviable dullness of spirit.’ (Olson 1985a on the name Pelagornis miocaenus)
Behaviour
Authors: Nelson J Bryan , Mackay Andrew , Busby John
Published: November 2023

These introductory remarks apply also to the behaviour sections of the General Family Accounts. Many ethologists see little point in further descriptive comparative studies of bird behaviour. Lorenz and Tinbergen long ago established major principles. For example, ritualized behaviour, so evident in pelecaniform display, evolves from simple precursors or ‘building blocks’; it is remarkably stereotyped and species-specific; communicative in function; in large part genetically programmed; its form often reflects a balance between conflicting motivations, principally aggression and fear; ‘displacement activities’ often arise and may themselves become ritualized; ritualized behaviour is often a reliable indicator of taxonomic affinity.
Breeding ecology
Authors: Nelson J Bryan , Mackay Andrew , Busby John
Published: November 2023

This chapter concerns some major aspects of pele-caniform breeding biology such as coloniality, tim-ing and frequency of breeding, clutch and brood size, chick growth, and breeding success. The diver-sity of the Pelecaniformesaffords particular insight into inter-related aspects of seabird breeding biol-ogy such as the adaptive web based on feeding and foraging regimes. Some cormorants and pelicans breed outwith the marine environment altogether, in the interiors of continents from sea-level to hundreds of metres above it, a range of habitats unmatched by any other seabird taxon. Pelecaniforms have adapted to most breeding habitats including flat ground, cliffs and slopes, trees, bushes and other vegetation.
Pelecaniforms and man
Authors: Nelson J Bryan , Mackay Andrew , Busby John
Published: November 2023

Pelecaniforms face the same formidable problems as many other seabirds and, like them, require active management based on legislation and education, global databases and monitoring, and coordinated international research (see Nettleship 1991; Nettleship and Duffy 1992). Technology offers powerful new tools not only for following the activities of the birds themselves but for modelling population dynamics and the interactions between seabirds and fisheries, and much else. Unfortunately we lack the most basic information: the numbers of the commoner and widespread seabirds. We know only that they are decreasing.
Gannets and Boobies
Authors: Nelson J Bryan , Mackay Andrew , Busby John
Published: November 2023

Black trailing edge of wing thus stops c. 12 cm short of body. Primary coverts usually black, may contain some white. Humerals, scapulars, tertials white. Alula black. Tail, usually 10 or 12 feathers, white except (usually) 4 central blackish but variable; 3–10 black feathers, outer 2 always white. Often, 1 or 2 variegated feathers separate white from black (see Broekhuysen and Liversidge 1954). The 4 black centrals with 4 white on each side does not indicate a more mature bird than one with variegated feathers. Head and neck golden buff varying with season. Bill and face as in Atlantic and African with black gular strip much as former.
Introduction
Authors: Hoffmann Ary A , Parsons Peter A
Published: November 2023

We commence with a definition of 'stress' to be used in this book because this term can take a number of meanings in a wide range of contexts. Discussions of stress in biology recognize two components, external or internal forces that are applied to organisms or other biological systems, and changes in biological systems that occur as a consequence of these forces. These two components are usually con sidered together because the impact of a force cannot be defined without reference to a biological system, and the term 'stress' has been applied to the change in the biological system, the force or both components simultaneously.
Genetic variation in stress response
Authors: Hoffmann Ary A , Parsons Peter A
Published: November 2023

Organisms respond to environmental stress with behavioural, physiological or morphological adjustments to counter its effects and maintain normal functioning. These adjustments can take the form of stress evasion or phenotypic changes to increase stress resistance (Section 1.3). Evasion reduces contact with the stress; resistance involves one of a complex of physiological or morphological responses that enable organisms to survive and reproduce under stressful conditions.
Stress response, costs, and trade-offs
Authors: Hoffmann Ary A , Parsons Peter A
Published: November 2023

From the discussion already presented, it is clear that individual differences in performance under stressful conditions will normally have a genetic basis. We now consider costs associated with increased stress resistance or evasion as expressed in a non-stressful environment. In other words, is there a trade-off between performance under stressful conditions and performance under other environmental conditions such that individuals that perform well under stress perform poorly in optimal environments? We start by discussing the physiological costs of stress resistance, then examine phenotypic variation in resistance and stress evasion. The evidence for trade-offs at the genetic level will be examined by considering specific genotypes and quantitative genetic variation. This includes a discussion of the association between genetic variation in stress resistance and life-history traits, and a consideration of the effects of stress on correlations among life history traits.
Stress, species margins, and conservation
Authors: Hoffmann Ary A , Parsons Peter A
Published: November 2023

In the preceding chapters we have demonstrated and analysed the features of genetic variation for stress responses within populations. Here we link genetic variation with the ecological considerations of the first two chapters. A number of theories of range expansion will be reviewed, emphasizing the role of genetic variation for stress response traits in limiting species distributions. The preservation of genetic variation for these traits is also considered. Adaptation to environ mental stresses is particularly important in the long term conservation of populations and species. An understanding of genetic changes under lying stress responses may clarify the ability of organisms to survive rapid environmental changes resulting from human activities, including the global warming predicted under the greenhouse scenario, the increasing impact of chemical pollutants, and the increased perturbations of the physical environment following habitat destruction.
Nodulins in root nodule development: function and gene regulation
Authors: Govers Francine , Bisseling* Ton
Published: November 2023

The symbiotic interaction between bacteria of the genus Rhizobium and leguminous plants leads to the establishment of nodules, specialized organs on the roots of the host plant in which the Rhizobium bacteria fix atmospheric nitrogen. The formation of root nodules is known to proceed through a series of characteristic stages (Vincent 1980). Prior to the actual infection, the symbiotic partners recognize each other and the bacteria become attached to the root hairs which then start to curl. The bacteria are entrapped in the curls and they induce the plant cells to deposit cell wall-like material from which a tubular structure is formed, the infection thread. Within the growing infection thread the bacteria multiply, but in front of the growing infection thread tip, in the cortex, mitosis is induced and a nodule primordium is formed. Once the infection thread tip has reached the primordium the bacteria are released in the plant cells and they are enclosed by a membrane. In plants which have indeterminate nodules, for example pea and alfalfa, a meristem is formed at the apical site of the nodule primordium. Continuous cell division, cell differentiation and cell enlargement finally result in a specialized plant organ.
Interactions between macrofaunal epiphytes and their host algae
Authors: Williams* Gray A , Seed† R
Published: November 2023

Marine algae provide a suitable habitat for a wide range of mobile and sessile macrofauna. Many of these organisms are permanent members of the epiphyton, whereas others utilize the host in a more transient fashion. Different types of algae support different suites of epiphytes according to the resources which the former provide. These include food and shelter as well as surfaces for attachment. Although some epiphytes are beneficial, others may impose a high selective cost on their host algae. Consequently the dynamic interactions between algae and their epiphytes are often extremely complex and not easy to categorize. In general, algae attempt to maximize associations with beneficial epiphytes and minimize encounters with those which impose excessive cost. Such complex interactions and the often close interdependence of epiphytes and host suggest a considerable degree of coevolution, though at present there is little conclusive evidence for this. This intriguing yet surprisingly neglected field of coastal ecology is clearly one which merits further detailed study.
Herbivorous fishes: feeding and digestive mechanisms
Authors: Horn Michael H
Published: November 2023

Feeding and digestion are sequential processes that seem to be especially tightly linked in herbivores, which are faced with a food resource not only low in protein and locked inside indigestible cell walls but also often chemically or morphologically defended. Herbivorous fishes browse or graze (if sediment is ingested) on their algal or seagrass foods with varying degrees of selectivity using a closely-spaced set of cropping or scraping teeth. These teeth may be conical or spatulate, smooth-edged, or cuspidate, flexible or rigidly attached, hinged or entire, separate and chisel-like or fused to form a beak-like structure.
Introduction
Authors: Dockray G J
Published: November 2023

Studies of the function and dysfunction of CNS systems that use CCK as a transmitter have now entered an especially exciting phase. In particular, the development in recent years of orally active antagonists for CCK receptors has opened the way for experimental studies that were hitherto impossible. The idea that CCK has a transmitter function in the CNS has developed over the last 15 years on the basis of evidence from many different disciplines. Even so, the availability of antagonists has been of crucial importance because for the first time it has become possible to formulate and test specific hypotheses of the functions of CCK in the intact nervous system.
Studies of gastrin/CCK receptors using functional isolated preparations
Authors: Patel Mina , Spraggs Colin F
Published: November 2023

CCK is widely distributed in the CNS, and attention at this symposium has focused on the potential central activities of this family of peptides. In addition, gastrin (G-17) and CCK are important physiological mediators of digestive function (Walsh 1987; Dockray and Gregory 1990). These observations have suggested the possibility of a number of therapeutic indications for selective agonists and antagonists at CCK receptors for use in the treatment of both CNS diseases (anxiety and schizophrenia) and gastrointestinal diseases (peptic ulceration, mucosal hyperplasia and tumour growth, motility, and digestive disorders).