bluuebunny/crossref_metadata_2025 huggingface dataset:
Parasitism by cuckoos
Authors: Davies N B , Quinn David
Published: November 2023

The main message of Chapter 12 was that dunnocks use simple rules to guide their parental effort. Females always feed the young in their nest and, in the absence of intraspecific brood parasitism (Chapter 7), they can have complete confidence that all the young dunnocks in their nest are their own. For males, the sharing of copulations reduces paternity but their use of mating access as a means of regulating their chick provisioning results in them directing most effort into broods where they have greater paternity.
Comparison of dominance relations and proportion of multi-female nests in the Polistinae
Authors: Itö Yosiaki
Published: November 2023

In this chapter I will discuss data relating to the frequency of intranidal dominance relations among female wasps, and to the proportion of multi-female-founding in the Polistinae. More than half the data about dominance-aggressive acts were collected by myself and will be discussed in detail in the following chapters, but the purpose of introducing these data in this chapter is to give readers a general picture of the social relations observed in wasps. I will also discuss here the methods used for describing social relations.The basic study methods were individual marking and direct observations. In my own observations, wasps were collected from nests using a small net or a vial, then slightly anaesthetized with carbon dioxide and marked with a soft pen containing oil-soluble coloured ink. (The sunshine-tolerant colour pen, ‘Opaque color’ made by Magic® is one of the most convenient soft pens to use.) I marked up to four points on the dorsal part of the wasps’ thorax using five colours. Then, while sitting or standing in front of a selected nest, I recorded verbally the behaviours of the wasps on the nest, using a cassette recorder, and later transcribed them.
Lesser mouse lemur
Authors: Kirkwood James K , Stathatos Katherine
Published: November 2023

The lesser mouse lemur is found throughout Madagascar except for the central plateau, and is relatively abundant and not threatened at present (Wolfheim 1983; Jolly 1986). It is found in a variety of forest and woodland habitats that contain relatively dense foliage (Wolfheim 1983; Martin 1972).
Chimpanzee
Authors: Kirkwood James K , Stathatos Katherine
Published: November 2023

Three subspecies are recognized: P.t. verus, the western chimpanzee; P.t. troglodytes, the central chimpanzee; and P.t. schweinfurthi, the eastern chimpanzee. Lee et al. (1988) and the IUCN (1990) classified the western subspecies, which occurs from Senegal to Nigeria, as endangered, and the other two which are found from Nigeria to the ZaЇre river and east of the ZaЇre river respectively, as vulnerable. These authors estimated that the total wild population might be 200 000 but accurate census data are not available for many parts of the range.
Myoglobin and Haemoglobin
Authors: Fermi Giulio
Published: November 2023

6.1 Introduction

This chapter is intended for the novice; the topics introduced here have been discussed in greater depth in the reviews of Baldwin (1975), Imai (1982), Perutz et al. (1987), and Perutz (1989). In general, additional references are cited in the text only when they would not be found readily in these reviews. The structures of a wide variety of globins have been determined but are not considered here. These include human fetal haemoglobin, haemoglobins with ligands other than oxygen, natural and artificial mutants, chemically modified variants, and globins from other species. The structure and function of a large number of variant human haemoglobins has been compiled by Perutz (Fermi and Perutz 1981); species differences in the globins have been subjected to structural analysis by Lesk and Chothia (1980).
RNA editing
Authors: Osawa Syozo
Published: November 2023

RNA editing can also be called ‘nucleotide substitution’-insertions or deletions made in the RNA sequence. Typically, deleterious changes that have occurred in DNA are restored at the RNA level by this process. The origins of the known forms of RNA editing in various organismic lineages are probably independent.
Photosynthetic Carbon Dioxide Fixation: Structural and Functional Aspects of Ribulose Bisphosphate Carboxylase/Oxygenase
Authors: Schneider Gunter
Published: November 2023

Every year, about 1011 tons of CO2 are incorporated into the biosphere by the photosynthetic activities of plants and microorganisms. Photosynthetic CO2 fixation proceeds through the incorporation of CO2 into ribulose bisphosphate (RuBP) which is then split into two molecules of phosphoglycerate. Part of the phosphoglycerate is used to synthesize energy-rich compounds such as starch or fatty acids. The remaining phosphoglycerate is used to regenerate RuBP, the primary acceptor of CO2, in a cyclic series of reactions, the reductive pentose phosphate or Calvin cycle.
Leaming from Rubisco’s Mistakes
Authors: Andrews T John , Morell Matthew K , Kane Heather J , Paul Kalanethee , Quinlan Gabriel A , Edmondson Daryl L
Published: November 2023

The reaction catalysed by Rubisco (D-ribulose-1,5-bisphosphate (ribulose-P2) carboxylase/oxygenase) is distinguished from other biological CO2-fixing re actions in having been chosen by nature as the means of acquiring nearly all of its carbon (for a review, see Andrews and Lorimer (1987)). Therefore, we have to ask ourselves not only how Rubisco functions but also how it is better than other potential CO2-acquiring mechanisms. Because we believe that, if nature had ever found a better mechanism for fixing CO2, then we would see that mechanism operating in photosynthetic organisms today. So, although most of this chapter is devoted to an analysis of Rubisco’ s many imperfections, it is important to emphasize at the outset that, imperfect though it is, Rubisco is still the best mechanism that has evolved for fixing CO2 under present atmospheric conditions.
Retrodiction of Carbon Dioxide Fixation towards a Chemoautotrophic Origin of Life
Authors: Wiichtershiiuser Gunter
Published: November 2023

Scientific theories aim at explaining the world. To explain means to reduce known facts to unknown assumptions. This is Popper’s crisp formulation. And it is true. When we explain in chemistry, we reduce known reaction products to unknown intermediates or unknown reaction mechanisms. When we explain in biology, we reduce known organisms to unknown missing links or an unknown mechanism of evolution. And when we explain in biochemistry, we try to reduce the known biochemical pathways to an unknown primordial metabolism, the origin of life. Alternative theories compete for the best explanation: for explaining more facts with fewer assumptions. They compete for explanatory power (Popper 1963).
Molecular biology and biochemistry of carbon dioxide-concentrating mechanisms in eukaryotic algae
Authors: Coleman John R
Published: November 2023

The ability of photosynthetic aquatic organisms to respond to fluctuations in the inorganic carbon (Ci) concentration of their environment is of considerable importance to the overall efficiency of algal carbon assimilation, and as such has been the topic of considerable research. Unlike the terrestrial environment, the supply of dissolved Ci available for photosynthesis is continually changing in response to a number of parameters such as turbulence (mixing rates with atmospheric gases), pH, and algal cell concentrations. For example, high concentrations of actively photosynthesizing algae can reduce dissolved Ci to levels well below air equilibrium and at the same time increase dissolved oxygen concentrations well above atmospheric levels. In other aquatic systems, although dissolved CO2 levels may be in equilibrium with atmospheric concentrations, the alkaline pH of water generates a large pool of Ci in the form of HCO3-. It would certainly be an advantage for the algae to access this pool as a substrate for photosynthetic carbon fixation. In general, wide variation in the dissolved Ci concentration and speciation in the aquatic environment has driven the evolution of a plastic response by these algae to changing Ci concentrations.
Habitat selection: patterns of spatial distribution from behavioural decisions
Authors: Kramer Donald L , Rangeley Robert W , Chapman Lauren J
Published: November 2023

Anyone who observes or tries to capture wild fishes soon becomes aware of patterns in their distribution. Each species is reliably found in some kinds of locality and not in others. Even within the confines of an aquarium, some species typically remain near the bottom, others near the surface; some stay in shelters, while others avoid such enclosed spaces. With experience comes a sense that one can even predict the size or sex of an individual from the characteristics of the site.
Neuropeptide growth factors: signalling pathways and role in cancer
Authors: Rozengurt E
Published: November 2023

Multicellular organisms have developed highly efficient regulatory networks to control cell proliferation. These involve cellular interactions with positive and negative diffusible modulators as well as with the extracellular matrix proteins. In fully mature organisms, the cells of many tissues and organs are maintained in a non-proliferating state (the G0/G1 phase of the cell cycle), but can be stimulated to resume DNA synthesis and cell division in response to external stimuli such as hormones, antigens or growth factors. In this manner, the growth of individual cells is regulated according to the requirements of the whole organism. The regulation of normal cell proliferation is therefore central to many physiological processes, including embryogenesis, growth and development, selective cell survival, tissue repair, and immune responses.
Apoptosis: a role in neoplasia?
Authors: Gregory C D
Published: November 2023

Over 20 years ago, Kerr et al. (1) proposed the term ‘apoptosis’ to describe a form of cell death which could be distinguished morphologically from necrosis, the passive mode of cell death which occurs as a result of cellular damage. It is now clear that the features of apoptosis mark a purposeful, self-destruction mechanism in which the cell plays an active part. The significance of such active or ‘programmed’ cell death is illustrated by its prominence as a regulatory mechanism in a diverse variety of systems ranging from the development of nematodes to the fine-tuning of mammalian immune responses (2). Like proliferation or differentiation, apoptosis should be regarded as a critical point of cellular control (3) which can be modulated physiologically, both by the cell itself and by its environment. Moreover, just as for proliferation or differentiation, interference with the normal regulation of this key process is likely to play an important part in the acquisition of a neoplastic phenotype (4). The purpose of this chapter will be to review current knowledge of the regulation of apoptosis, focusing on its potential to influence both the evolution and destruction of malignant cells.
A new view of the world
Authors: Humphries Christopher J , Parenti Lynne R
Published: November 2023

Integration of cladistics and biogeography developed from the understanding that theories of biogeography, as well as those of systematics, must be testable to be scientific and, therefore, to be incorporated into theories of earth history. But, we gain little from integration of the two fields unless it can tell us something new about the world.
Anaerobic environments
Authors: Fenchel Tom , Finlay Bland J
Published: November 2023

It is rather difficult to produce a comprehensive and useful definition of ‘anoxia’. Part of the problem lies in the different perspectives held within different scientific disciplines: a geologist, an animal physiologist and a microbiologist, for example, will invariably have differing ideas on what constitutes significant oxygen-depletion.
Interactions with the oxic world
Authors: Fenchel Tom , Finlay Bland J
Published: November 2023

Anoxic environments do not exist in isolation from their oxic surroundings. As emphasized in Chapter 1, reducing power for the maintenance of anoxic environments, and the chemical energy needed by their inhabitants is, with a few exotic exceptions, provided by the oxic world in the form of organic material produced by oxygenic phototrophs. This situation has prevailed throughout most of the history of the Earth. Moreover, oxygen is necessary for the completion of biogeochemical element cycles; thus, nitrate and sulphate are regenerated from ammonia and sulphide through oxidation with 02 (although some sulphide oxidation is carried out by phototrophs under anaerobic conditions).
Travelling waves in heterogeneous environments
Authors: Shigesada Nanako , Kawasaki Kohkichi
Published: November 2023

We have so far dealt with range expansions in homogeneous environments. As we saw in Chapter 2, however, the actual spreading range front is more or less irregularly shaped, never realizing concentric circles that spread at constant intervals as predicted by the Fisher model. Needless to say, the reason for this is that the invading species encounters rivers and hills in the course of its range expansion, and thus changes its rate of spread depending on the type of terrain. In this chapter, we study range expansion in a heterogeneous environment in which favourable and unfavourable habitats are distributed in patchwork fashion. When the invading species enters an unfavourable patch, it will be able to expand its range only if it successfully survives in that patch and reaches a favourable one lying ahead. If unfavourable patches dominate, the population may become extinct without expanding the range.
Reproductive behaviour
Authors: Frith Clifford B , Beehler Bruce M , Cooper William T , Mcguire Michael
Published: November 2023

The birds of paradise have long figured as prominent examples of sexual dimorphism and unusual mating behaviour. Charles Darwin referred to them on 12 occasions in The Descent of Man and Selection in Relation to Sex (1871). Most of Darwin’s knowledge of this bird family was borrowed from the writings of his colleague and fellow evolutionist, Alfred Russel Wallace. So taken was Wallace by the beautiful plumages and bizarre courtship behaviour of the birds of paradise that he spent months searching for them in the field (with more disappointment than success), and he included them in the subtitle of his most enduring work, The Malay Archipelago (1869).
Introduction
Authors: May Robert M
Published: November 2023

Underlying all discussions of the diversity of life on earth is a fundamental question, which is rarely asked and which is at present unanswerable. Is ours the only inhabited planet in the universe? Or is the evolution of some form of life a cosmic commonplace, occurring in some appreciable fraction of planetary systems?

One post-Copernican reflex is to deny any such special status for our planet. But the suggestion that we are unique is not necessarily anthropocentric. We could be here, asking these questions, simply because we are the end product of a wildly improbable chain of events, the winners of a lottery against literally astronomical odds. A converse view is that complex self-replicating molecules, followed in time by multicellular organisms, and eventually by self-conscious entities of some kind, are likely to evolve on many planets (or at least many of those with water). Sums of money beyond the dreams of the most scientifically avaricious systematists and ecologists have indeed been spent on radio-astronomical and other quests for signals from inhabited planets more technically advanced than ours. And although few evolutionary biologists are aware of it, there exists a scholarly literature arguing that life might frequently originate, but nevertheless most of the universe may be empty at any one time (thus explaining ourxs failure as yet to detect any interstellar signs of ‘others’).
What can phylogenetic patterns tell us about the evolutionary processes generating biodiversity?
Authors: Harvey Paul H , Rambaut Andrew , Nee Sean
Published: November 2023

What can the structure of molecular phylogenies tell us about the evolutionary processes responsible for their genesis? Remarkably little attention has been paid to answering this question, despite the rapid accumulation of molecular sequence data which allows the construction of ever more precise phylogenetic trees. Our goal in this chapter is to provide research groups examining particular taxa with a set of routine procedures for extracting the footprints of the past that may lie hidden in their sequence data. Elsewhere, we have presented illustrative examples showing the types of conclusions that we believe can or cannot be derived from molecular phylogenies. It is not our intention to go over the same ground here, although we shall summarise some relevant points of this previous work insofar as they are relevant to our immediate aim.

Phylogenetic trees based on molecular data can tell us when, on absolute or relative time scales, independently evolving lineages last shared common ancestry. The footprint of the past, which we wish to interpret, consists of the relationships among the times between the nodes in the tree (Fig. 3.1).
Biodiversity of parasites in relation to their life-cycles
Authors: Morand Serge
Published: November 2023

Parasites with simple life-cycles (SLC) require a single host individual in their development, whereas complex life-cycle (CLC) parasites need several hosts. Several groups of parasites are composed entirely of complex life-cycle species (CLC) with at least one intermediate host and one definitive host, as in the case of digenous trematodes, cestodes and acanthocephalans. Although the intermediate host can serve as the site of parasite reproduction, it can also shelter infesting stages and be a prey for the definitive host, with the parasite then becoming an integral part of a predator-prey network.

Few studies have tried to understand the evolution and maintenance of complex life-cycles (Dobson 1989; Dobson and Merenlender 1991; Esch and Fernandez 1993), or the influence of CLC parasites on the dynamics of a multi-species system. Recently, Freeland and Boulton (1992) argued that CLC parasites may predominate parasitic associations and that they may stabilize multi-species systems.
Causes of developmental instability. Environmental factors
Authors: Møller Anders Pape , Swaddle John P
Published: November 2023

A large number of environmental factors can result in a reduction of developmental stability and increased levels of fluctuating asymmetry in bilateral traits. The list of factors is almost endless and the review given here is not exhaustive but merely a representation of the kinds of factors that researchers have thought important in explaining the variations in fluctuating asymmetry that they have observed. These may be tied to the natural ecology of the species studied, or limited to the laboratory equipment through which the investigator can manipulate the developmental conditions of the study organism.
The energetics of pteropodid bats
Authors: Mcnab Brian K , Bonaccorso Frank J
Published: November 2023

The temperature regulation and energetics of pteropodid bats are highly variable. Their thermoregulation is effective in species that weigh more than 60 g, but smaller species often exhibit imprecise regulation at cool environmental temperatures. The smallest nectarivores usually maintain a small temperature differential with the environment, especially at low altitudes. Nectarivores either regulate body temperature at high altitudes or are limited in distribution to lowlands. Basal rate in pteropodids varies with body size, with the propensity to enter torpor and with the size of the island on which pteropodids are found. The low rates of metabolism found in small-island Pteropus, produced directly or by a reduction in body mass, reduce resource use in an environment characterized by limited resources. A lower rate of metabolism is also found in species of Dobsonia endemic to small islands, compared with mainland Dobsonia of the same size, and in the genus Melonycteris, which is endemic to small islands, compared with the equally sized Eonycteris from Borneo. Large Pteropus reduce heat loss at low environmental temperatures, probably through peripheral vasoconstriction, thereby permitting rate of metabolism to fall without compromising the maintenance of a high core temperature. We conclude that the evolution of specialized nectarivory, which appears to have occurred independently at least five times in the Pteropodidae, is usually associated with a reduction _in both mass and rate of metabolism, a combination that leads to a variable body temperature.
Dispersal and philopatry in colonial animals: the case of Miniopterus schreibersii
Authors: Palmeirim Jorge M , Rodrigues Luisa
Published: November 2023

The dispersal behaviour of Miniopterus schreibersii, a colonial cave-dwelling bat, was studied with data obtained by recovery of animals ringed in the eight maternity colonies known in Portugal. The results showed that this species has a strictly philopatric behaviour during the nursing season; females return to give birth in the colony where they were born and very seldom change maternity colony during their lifetime. Males also showed a high level of attachment to their birth site, although during the nursing season most of them roosted in other locations with nonbreeding females. This strictly philopatric behaviour is due to strong imprinting, rather than to lack of knowledge of alternative roosts. Imprinting to maternity colonies takes place during the first weeks of life, and not during the first breeding season.
Does energy or calcium availability constrain reproduction by bats?
Authors: Barclay Robert M R
Published: November 2023

Bats are unusual mammals in being small but having long lives and small litters (typically only one or two young). I hypothesize that litter size is constrained by the need to raise young to near adult size before they can be independent. Our studies, and those of others, on a variety of species of bats indicate that juveniles typically start to fly at over 70% of adult mass and over 95% of adult skeletal size. This constraint appears to be associated with flight in vertebrates, since young birds also do not fly until fully grown. This means that each young is very costly and restricts the number that can be raised. Although energetic demands may be the proximate constraint, I argue that calcium is more important. For bats, calcium demand on reproductive females is high and calcium availability in most diets (insects, fruit, pollen) is low. Birds can at least partially overcome this by supplementing their diet with calcium-rich inanimate objects that are unavailable to bats because of their inability to forage on the ground and detect such items. This may help to explain why the reproductive output of birds exceeds that of bats. If the hypothesis is correct, bat foraging strategies may be based on the calcium content of prey in addition to energy content, and female and male foraging strategies may be based on different currencies. Vertebrate-pollinated and seed-dispersed plants may attract bats by offering high calcium rewards. In addition, however, it would mean that flight could only have evolved in bats in association with long lifespans, thereby constraining the possible life histories available to these mammals.
The trophic niches of sympatric sibling Myotis myotis and M. blythii: do mouse-eared bats select prey?
Authors: Arlettaz Raphael , Perrin Nicolas
Published: November 2023

The two sibling species Myotis myotis and M. blythii, while sympatric in the Swiss Alps, exhibit highly distinct and narrow trophic niches. Does this differ entiation arise purely from the use of distinct feeding habitats or, alternatively, do the species exert active prey selection within their feeding habitats? To answer this question, we compared the distribution of prey in the species’ diets with that in their respective feeding habitats, looking for discrepancies with respect to taxon and/or size. Although the general correlation is fairly good, some local discrepancies arise: (1) M. myotis underexploited small prey items (<0.05 g dry weight), and (2) M. blythii overexploited cockchafers (Melolontha melolontha) and underexploited ground arthropods. We argue, however, that these discrepancies do not result from active prey selection, but from (1) the low availability of some categories of prey (due to either low detectability or low accessibility) and (2) the opportunistic exploitation of atypical feeding habitats. In fact, our results do not falsify the parsimonious hypothesis that the two species exert no active prey selection within their feeding habitats. We are furthermore not aware of any paper from the bat literature that provides definite support for active prey selection among insectivorous vespertilionids. Their echolocation system may actually preclude it.
MS/MS instrumentation
Authors: Jennings Keith R
Published: November 2023

Since mass spectrometers became widely available commercially about 40 years ago, they have proved of considerable value in the determination of the structures of many classes of pure compounds. When used in conjunction with separation techniques such as gas chromatography (GC) and highperformance liquid chromatography (HPLC), they have proved to be equally useful in identifying components of complex mixtures. In each type of application, it is assumed that the ionization process will give rise to a significant number of fragment ions from which structural information may be deduced. As the polarity of the sample increases, thereby reducing its volatility, the applicability of ionization techniques such as electron ionization and chemical ionization decreases and ionization must be effected by using one of several desorption ionization methods. Although these have the advantage that they considerably extend the mass range of samples that may be ionized, they normally give rise to very few fragment ions. They are therefore primarily of use in helping one determine the relative molecular mass (RMM) of samples, but when used in conjunction with a standard type of mass spectrometer they give little structural information.
Mass spectrometry of fatty acid derivatives
Authors: Christie William W
Published: November 2023

The potential of mass spectrometry (MS) for the identification of fatty acids of natural origin has been evident for many years. However, until relatively recently there were few reports of structural analyses on real samples containing unsaturated fatty acids as opposed to model compounds. The topic has been the subject of several reviews (Minnikin 1978; Schmitz and Klein 1986; Jensen and Gross 1987; Murphy 1993). The main problem has been the location of double bonds, although there have also been difficulties with ring structures or branch-points. There are three general approaches to the location of double bonds in unsaturated fatty acids by MS: (i) they can be ‘fixed’ by preparation of specific chemical adducts, which give distinctive fragmentation patterns; (ii) tandem MS techniques can, in some circumstances, give valuable structural information; and (iii) specific amide or ester derivatives, which, following ionization, stabilize the charge on a nitrogen atom remote from the double bonds, can be prepared. With this last approach, radical-induced cleavage predominates in the mass spectrometer and distinctive fragmentations are achieved according to double-bond position. In particular, the use first of pyrrolidine (reviewed by Andersson 1978) and more recently of picolinyl ester or 2-alkenyl-4, 4-dimethyloxazoline (DMOX) derivatives (Fig. 13.1) (reviewed by Harvey 1922) of fatty acids permits gas chromatography (GC)-MS to be employed in a simple manner for the simultaneous separation and characterization of these compounds from natural lipid extracts.
New brassinosteroids from Ornithopus sativus and Apium graveolens
Authors: Schmidt J , Spengler B , Voigt B , Adam G
Published: November 2023

Brassinosteroids represent a class of naturally occurring phytohormones with plant growth stimulating and antistress activity (Cutler et al. 1991; Sakurai and Fujioka 1993; Adam and Petzold 1994). In the course of our investigations concerning the occurrence of brassinosteroids in European cultivated plants we have investigated both seeds and young shoots of the legume Ornithopus sativus (Serradella) as well as seeds of the umbellifer Apium graveolens (celery). GC-EI MS is a very sensitive and valuable method for the identification of brassinosteroids because of the low content of these compounds in plant material (ng- to µg-level/kg plant material) (Ikekawa and Takatsuto 1984). The most suitable and common brassinosteroid derivatives used for the GC-MS analysis are the methaneboronates and the methaneboronates/trjmethylsilyl ether (Takatsuto et al. 1982).
Generating animal models of human mitochondrial genetic disease using mouse ES cells
Authors: MacGregor Grant R , Wei Wei Fan , Waymire Katrina G , Wallace Douglas C
Published: November 2023

The use of mouse ES (mES) cells to generate transgenic animals has revolutionized the study of gene action in vivo, and has provided animal models for studying the pathophysiology of human genetic disease and therapies thereof. Since the discovery that inherited mitochondrial DNA (mtDNA) mutations can cause age-related degenerative diseases (1), it has been realized that inherited mtDNA mutations are also associated with human adaptation to different environments, a broad spectrum of degenerative diseases, and with cancer. Somatic mtDNA mutations can accumulate during the lifetime of the individual, and have been implicated in the onset and progression of age-related diseases, and of ageing and cancer. Indeed, the importance of somatic mtDNA mutations in ageing has been affirmed by the expression in mice of a mutant form of mtDNA polymerase γ subunit A, which contains a D257A mutation that inactivates the 3 ′−5 ′ endonuclease. These animals have an increased mtDNA mutation rate and age prematurely (2). These findings highlight the pressing need for animal models of mitochondrial disease to better understand the role of the mitochondrion in the pathophysiology of disease, and in human genetics.
In vitro differentiation of mouse ES cells into pancreatic and hepatic cells
Authors: Blyszczuk Przemyslaw , Kania Gabriela , Wobus Anna M
Published: November 2023

In mammalian development, both the pancreas and liver originate from the definitive endoderm. The pancreas develops from dorsal and ventral regions of the foregut, and the liver from the foregut adjacent to the ventral pancreas compartment (1, 2). At present, the lack of available methods for enriching either pancreatic or hepatic progenitor cells from their respective organ in vitro is a major obstacle for the efficient generation of selected, pure populations of derivative cells. Moreover, the progenitor cells of the liver and pancreas are not yet clearly defined. Nestin-positive cells deriving from pancreatic islets, and generated after in vitro culture, are suggested to represent pancreatic progenitor cells (3); and oval cells are regarded as hepatic stem/progenitor cells (4). However, cells residing in the pancreatic (5) and hepatic (6) ductal epithelium and expressing cytokeratin 19 also have been proposed as pancreatic and hepatic stem or progenitor cells in vivo.
The significance of Ewald’s dynamical theory of diffraction
Authors: Kato Norio
Published: November 2023

Professor Ewald passed away at the age of 97, on 22 August 1985 at Ithaca, the university town for Cornell where he spent the last period of his life. When I received the news, I fell into deep grief. After a year or so, however, considering his age in particular, I began to think more about his scientific achievements themselves and what we could do to develop them. It was very natural, therefore, that a ‘microsymposium’ with this aim had been planned in the 1987 Congress of the IUCr (International Union of Crystallography) at Perth, Australia.
Paul P. Ewald–a personal appreciation
Authors: Juretschke Hellmut J
Published: November 2023

Most of the other contributions to this volume deal eloquently with the various primarily scientific ideas and accomplishments of Paul Ewald himself or flowing out of his work. I would like to fill in some more of the background of his numerous broader public contributions to crystallography. At the same time, I would also like to remember him as a friend and colleague, and to touch upon how I saw him in more private roles.
The reciprocal lattice imbedded in Fourier space
Authors: Cruickshank D W J
Published: November 2023

The first point to make is that Ewald’s introduction of the reciprocal lattice and the sphere of reflection grew directly out of his dynamical theory, and not from any examination of purely geometrical aspects of diffraction.
X-ray topography
Authors: Authier A , Capelle B
Published: November 2023

In the theory of dispersion [... ] an important role is played by the reciprocity theorem. That is to say, if you have a ray falling in one direction and generating a secondary ray in another direction, then, if you let the incident ray take the direction of the secondary one, the primary ray will also be generated again. So this showed that you cannot consider a single wave but you have to consider a whole bundle of waves or, as we now say, a wave field propagating in the crystal, instead of a single wave which is sufficient in Optics. P.P. Ewald (from a lecture given at the International School on X-ray Topography and Dynamical Theory, Limoges, August 1975).
Personal Reminiscences
Authors: Ewald P P
Published: November 2023

The Editor insists on my writing for this issue rather more personal reminiscences than are scattered throughout Fifty Years of X-ray Diffraction. Remembering the pleasure I got when reading the personal reminiscences of my friends and colleagues written for that book, I reluctantly comply.
Computing for High Resolution Images and Diffraction Patterns
Authors: Barry J
Published: November 2023

The computation of images and diffraction patterns is necessary because electrons interact strongly with matter. Even for a crystal of less than 100 A thickness, the transmitted electrons undergo multiple elastic scattering. Because of the strong multiple scattering, the amplitudes and phases of the resultant Bragg beams cannot be directly related to the structure factors. In order to solve the structure fom a given diffraction pattern of an unknown structure, it is necessary to compute diffraction patterns for a trial structure, and compare with the experimental results. For high resolution lattice images the need for computation is even more imperative because of the additional effects of objective lens defocus and microscope resolution.
Identification of Unknowns in Electron Diffraction
Authors: Carr M J , Lyman C E , Cowley J M
Published: November 2023

As is the case for x-ray diffraction, a large proportion of electron diffraction studies have the aim of confirming or revealing the presence in a sample of one or more previously-known phases. This implies the collection from the sample of sufficient information to allow the identification to be made by use of one or more of the existing data-bases. For a phase not previously characterized it may be desirable to carry out a more detailed investigation, and possibly a complete structure analysis, using the techniques outlined in Chapters 6 or 7. However the number of phases which have been adequately characterized is now so great that in most cases the identification of an “unknown” involves only its recognition as a previously “known” phase.
Convergent-Beam Diffraction
Authors: Eades J A
Published: November 2023

In the transmission electron microscope, the intensity transmitted in the direction of the incident beam by a crystalline sample is a complex function of the angle the incident beam makes with the crystal structure. An example of this spectacular variation is given in figure 7.1, which shows, as a function of angle, the intensity of the beam transmitted through gallium arsenide near [100]. There is a comparably complex variation of the intensity of each of the diffracted beams, except that the diffracted beams have intensity only for a range of angles close to the Bragg angle (figure 7.2).
Accurate Structure Factor Amplitude and Phase Determination
Authors: Spence J C H
Published: November 2023

The history of structure factor measurement by transmission electron diffraction may be divided into three areas (i) The study of the three-beam dynamical theory of electron diffraction and its degeneracies, (ii) Improvements in the algorithms and hardware used for dynamical computations, and (iii) Advances in electron microscope design and performance. This chapter reviews developments in each of these areas. A summary of most of the measurements which have been made is given, together with a detailed description of experimental methods. A review of useful results from three-beam theory is also given.
D
Authors: Atkins P W
Published: November 2023

non-zero angular momentum ensures that a d electron never approaches very close to the nucleus: the repulsive centrifugal force of the motion rises more rapidly than the attractive Coulombic force, and the net force is repulsive as r approaches zero. The boundary surfaces of the five real forms of the wave functions of the 3d orbitals are shown in Fig. D.1 (the boundary surfaces of other d orbitals are similar). All the orbitals have two nodal planes. The peculiar shape of the d22 orbital is a result of forming linear combinetions of the °complex forms of the orbitals in order to depict them more simply. Figure D.2 indicates how the five orbitals look when represented as complex wave functions, which is appropriate when we want to identify each orbital with a specific value of m1: now they all look like members of the same family.
L
Authors: Atkins P W
Published: November 2023

The lanthanide contraction is the striking reduction in atomic and ionic radius that occurs across the first row of the f block and which leaves the subsequent elements of Period 6 with smaller radii than would have been expected by extrapolation from previous periods. Similar contractions occur in the d block, and have been named (but apparently not entirely seriously) ‘scandinide contractions’. The origin of the lanthanide contraction is the poor shielding provided by the f electrons. Although the poor shielding is conventionally ascribed to the highly angular character of the orbitals, a closer analysis shows that the true explanation lies in their radial character. First, we should note that the 4f orbitals make only a minor contribution to the electron density in the outer reaches of the atom, so the electron density in the 5s and Sp orbitals determines the atomic radius.
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Authors: Atkins P W
Published: November 2023

According to quantum mechanics, all the dynamical information about a system is contained in its °wave function. The outcome of an observation of a particular property can be predicted by performing the appropriate mathematical operation on the wave function. Each physical observable is therefore represented by an operator, a mathematical action such as multiplication or differentiation. The operator corresponding to the observable Q is often denoted fi, but we shall not make that distinction here. Different choices of operators for observables correspond to the different representations of quantum mechanics.
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Authors: Atkins P W
Published: November 2023

Heisenberg’s uncertainty principle states that:

The product of the uncertainties in the simultaneous specifications of two °complementary observables can never be less than a small quantity of the order of h. The precise form of the principle is given in Box U.1. It implies that as one observable is constrained to have a more precise value, so its partner becomes more ill-defined. An experiment designed to measure the two observables simultaneously will be able to determine one precisely only at the expense of losing information about the other (see °duality). The principle was established by Werner Heisenberg in 1927, as a consequence of his formulation of °matrix mechanics.
The early days: a retrospective view
Authors: Rietveld Hugo M
Published: November 2023

As a Ph.D. student at the University of Western Australia between 1961 and 1964, I became thoroughly acquainted with X-ray and neutron diffraction techniques through experiments being conducted at the HIFAR in Lucas Heights (NSW). The emphasis was on single crystal diffraction since, even then, the powder method was regarded to be inferior, particularly for structure refinement. During that period the computer entered the scientific field and long, tedious structure factor and density calculations could be obtained more or less instantly. First with the ‘Mercury’ computer at the University of Oxford and the ‘Silliac’ computer at the University of Sydney, and later the IBM 1620 at the Physics Department of the University of Western Australia, computers became an integral part of my crystallography work. They were, incidentally, also important for my later work.
Mathematical aspects of Rietveld refinement
Authors: Prince Edward
Published: November 2023

The method of least squares is a powerful technique for estimating the values of the adjustable parameters in a model, M(x), that predicts the values of a set of observable quantities, y. One seeks the minimum, as a function of x, of the quadratic form.
Data collection strategies: fitting the experiment to the need
Authors: Hill Roderick J
Published: November 2023

The abundance and complexity of the structural and physical information that can be extracted from powder diffraction patterns is approaching that obtainable from single crystal data. It is advisable, therefore, that careful consideration be given to the selection of the conditions under which powder data is collected and to the effect of these choices on the capabilities and results of the analysis. The fundamental measured quantities (observations) for crystal structure refinement using powder diffraction data are the intensities of the Bragg peaks; the intensities collected at each step in the pattern serve only as multiple, variably-weighted, estimates of these values. The precision of the peak intensity measurement can be improved by increasing the number of counts accumulated at each step and/or the number of steps measured across the peak, but this is useful only up to the point where counting variance becomes negligible in relation to other sources of error; thereafter, time is wasted.
Rietveld refinement with time-of-flight powder diffraction data from pulsed neutron sources
Authors: David W I F , Jorgensen James D
Published: November 2023

The recent development of accelerator-based pulsed neutron sources has led to the widespread use of the time-of-flight technique for neutron powder diffraction. The properties of the pulsed source make possible unusually high resolution over a wide range of d-spacings, high count rates, and the ability to collect complete data at fixed scattering angles. The peak shape and other instrument characteristics can be accurately modelled, which makes Rietveld refinement possible for complex structures. In this chapter we briefly review the development of the Rietveld method for time-of-flight diffraction data from pulsed neutron sources and discuss the latest developments in high resolution instrumentation and advanced Rietveld analysis methods.
Waves in a Hot Plasma
Authors: Brambilla Marco
Published: November 2023

In this chapter we will investigate the effects of the thermal motion of ions and electrons on the propagation of h.f. waves in plasmas. As a preliminary, it is useful to introduce notations for the dielectric tensor components and for the hot-plasma dispersion relation which take into account the considerations made in Section 15.5, and what we already know about wave propagation in a cold plasma.
Numerical Methods For Transition Regime Flows
Authors: Bird G A
Published: November 2023

As was noted in the preceding chapter, very few of the ‘analytical’ methods lead to closed form solutions and most depend on numerical procedures for the production of the final results. On the other hand, the ‘numerical’ methods rely on computation from the outset. While the analytical methods are almost invariably based on the Boltzmann equation which is the accepted mathematical model of a gas flow at the molecular level, a large fraction of the numerical methods are based directly on the simulation of the physics of the flow and do not depend on a mathematical model. This difference in approach can be used to define two classes of methods, but the situation is complicated by the efforts that have been made to link some of the simulation methods to the Boltzmann equation with sufficient rigour that they can be claimed to be ‘solutions’ of that equation. All methods that employ simulated particles or molecules will be classed here as simulation methods.
Sand Behaviour Under Monotonic Loading
Authors: Ishihara Kenji
Published: November 2023

A deposit of sand is composed of an assemblage of particles in equilibrium where inter-granular forces are transmitted through points of contact. When shear stress is applied, the resulting deformation is always accompanied by a volume change which is known as dilatancy. This shear-induced volume change accrues as a result of two competing modes of particle movement, namely, slip-down and roll-over (Dafalias, 1993). The slip-down movement of grains tends to reduce the volume by repacking the sand aggregate into a denser state. This mechanism is activated predominantly in loose deposits of sand. The roll-over mechanism tends to increase the volume which is characteristic in the behaviour of dense sand. When the slip down takes place, particles are filling gaps in the void and not moving largely in the direction of shearing. Therefore the slip-down movement can occur rather easily without mobilizing a large amount of shear strain. It is for this reason that the volume reduction is generally observed at an early stage of loading in the tests on sands with a wide range of density. On the contrary, a larger movement is always required for particles to roll over neighbouring ones and hence the volume increase or dilation is generally induced at a later stage of shear stress application where the sand is largely deformed.
Mass transfer coefficients, interfacial effects, and Surface Renewal
Authors: Javed K H
Published: November 2023

Mathematical models describing the mechanism of mass transfer across liquid-liquid interfaces are of basic importance in the prediction of mass transfer coefficients for use in the design of industrial contacting equipment.
Liquid-Liquid Extraction in Hydrometallurgy
Authors: Cox Michael
Published: November 2023

Hydrometallurgy involves a series of interlinked unit processes for the recovery and purification of elements using aqueous solutions. One of the essential features of present flow sheets is the inclusion of a solution treatment step to purify and concentrate the desired element before recovery. Several alternative techniques are available but liquid-liquid extraction has the greatest versatility for the separation of elements and also the range of solution concentrations which can be treated. This process is therefore now seen as the preferred technique for the treatment of all except the most dilute leach liquors, such as in gold and some uranium operations where resin ion exchange and carbon adsorption processes offer distinct advantages (Streat and Naden 1987). Although a detailed discussion of hydrometallurgy is outside the remit of this chapter, it is appropriate to consider the demands made by such a flow sheet (Fig. I. I) as these will influence the choice and operation of the liquid-liquid extraction system.