bluuebunny/crossref_metadata_2025_split huggingface dataset:
Local diversity: a problem with too many solutions
Authors: Shorrocks Bryan 
Published: November 2023

Abstract
Population ecologists have increasingly become interested in multi-species ecology. This is clearly shown in an analysis of papers published in the Journal of Animal Ecology (JAE), between 1932 (the first volume) and 1992 (Shorrocks 1993). In the early days, population ecologists were predominantly interested in understanding the dynamics of single species systems. There were papers in JAE on multispecies communities, but they were simply descriptive. Following the golden age of the ‘bottle experiment’ (Kareiva 1989) when theoretical ideas about two-species interactions were rigorously scrutinised in the laboratory (Gause 1934; Crombie 1946; Park 1948; Utida 1953, 1957) interest in the dynamics of multi-species systems grew. This dialogue between theory and experiment laid the foundations for what was to become the dominant explanation for local biodiversity (MacArthur 1972)-resource partitioning. However, there are many levels of species diversity, and there are other possible mechanisms which may help to explain the local coexistence of species. In this chapter I will examine species diversity in a model group of insects-Drosophila.
Trophic interactions, nutrient supply, and the structure of freshwater pelagic food webs
Authors: Lacroix Gérard , Lescher-Moutoué Françoise , Pourriot Roger 
Published: November 2023

Abstract
Limnological studies in the first half of the century largely considered the effects of abiotic factors on aquatic communities, with those few studies on biotic interactions tending to focus on the lowest trophic levels (Persson et al. 1988). In the early 1960s, limnological studies were conducted for a large part in the context of ‘bottom-up’ tropho-dynamic concepts (Liebig’s law of limiting factors, efficiency of energy transfers between trophic levels ... ), in particular within the scope of the International Biological Program. This bottom-up view was reinforced in the late 1960s with the understanding of the major role of nutrient loading in lake eutrophication.
During this same period, some key papers (Hutchinson 1961, Hrbacek et al. 1961, Brooks and Dodson 1965) were published, stimulating for three decades an impressive number of descriptive, experimental, and theoretical studies on the respective roles of predation and competition in plankton communities. These studies led to substantial progress in the comprehension of organisms’ life histories, population dynamics, species-specific interactions, and coexistence within aquatic food webs (Kerfoot 1980, Tilman 1982, Lampert 1985, Sommer 1989).
Does climate cause the global biodiversity gradient?
Authors: Turner John R G , Lennon Jack J , Greenwood Jeremy J D 
Published: November 2023

Abstract
The fundamental question of biodiversity ‘why are there so many kinds of organisms?’ (Hutchinson 1959, May 1990) is easily answered in broad outline: the number of species on the planet must be governed by a dynamic equilibrium between the rate of speciation and the rate of global extinction. But a further outstanding fact about biodiversity is that it is unevenly distributed: in most groups of organisms (there are major exceptions-Hawkins 1990) there are many more species in the tropics than at higher latitudes. Diversity is very low indeed in the polar regions. Answering the question ‘why does this diversity gradient occur?’ might be an adjunct to the answer to the fundamental question, or it might contain a crucial insight into the answer to the fundamental question. It may require several different answers (Begon et al. 1986, Currie 1991). The species-energy theory, or as Turner (1992) has called it, the dynamic theory, is comparatively neglected among the many theories that have been advanced: for instance, very few front line textbooks mention it. Only since Lawton’s (1990), Currie’s (1991) and Rohde’s (1992) reviews has the theory received wide publicity, after a slow recovery from relative neglect (Brown and Gibson 1983, Wright 1983, Currie and Paquin 1987, Turner et al. 1987, Wright et al. 1994). It is still misunderstood by many, and has been widely regarded as ridiculous, trivial or obvious.
Antarctic Cheilostomatous Bryozoa
Authors: Hayward P J 
Published: November 2023

Abstract
Bryozoans are encrusting colonial organisms which are ubiquitous in freshwater and marine environments. As the dominant sessile organisms of the Antarctic shelf seas, they are a pivotal component of the ecosystem. This is the first identification guide to the Bryozoa and describes and illustrates all 264 species of cheilostomate Bryozoa which have been recorded from the Antarctic seas. It includes an illustrated dichotomous key to the genera, and for each genus there is a key to Antarctic species. All species are fully described, and a clear diagnosis is given for each genus, family, and superfamily.
Introduction
Authors: Hayward P J 
Published: November 2023

Abstract
Systematic research on the Antarctic Bryozoa has a comparatively short history. The first marine invertebrates to be described from Antarctica were a few molluscs and crustaceans collected from strand line debris on the South Shetland Islands by James Eights, surgeon and naturalist with the U.S. Antarctic Exploring Expedition (Eights 1833). It is probable that Eights encountered bryozoan colonies among the beach debris, but he neither collected nor recorded them (Winston and Hayward 1994). James Clark Ross made the first dredge hauls in Antarctic coastal waters in 1841, in the course of the Erebus and Terror Antarctic expeditions. It is known that he and Joseph Dalton Hooker made extensive collections of Antarctic marine invertebrates. Hooker prepared illustrations of many of the specimens they collected, including some collected while en route to Antarctica, and the surviving drawings, conserved at the Natural History Museum, London, apparently include a number of bryozoans (Davenport and Fogg 1989), but Ross’s collections were not worked up and were eventually destroyed. Antarctic bryozoans were not collected again until Michaelsen’s visit to South Georgia in 1892-1893.
Systematic Accounts
Authors: Hayward P J 
Published: November 2023

Abstract
Colony consisting of uniserial, branching chains of autozooids, each comprising an adnate proximal portion, and an erect, tubular, distal portion. The adherent proximal portions give the appearance of a continuous, branching stolon, filiform or with regular dilatations, with the tubular distal portions (sometimes spatulate at the free end) regularly spaced along its length. In some instances the proximal ‘stolonic’ portions are only partly attached to the substratum, and the colony develops a diffuse, bushy form. Each autozooid comprises an attached proximal portion, a cylindrical middle region of varying length, and a distal region bearing the frontal membrane. Operculum terminal. Polypide with few tentacles, generally 12-20, and with a delicate circlet of fine teeth around base of lophophore. Embryos brooded in membranous sacs borne externally at distal end of autozooid. Small kenozooids may be intercalated between proximal portions of successive autozooids in some species; other polymorphs do not occur.
Asymmetries and developmental stability
Authors: Møller Anders Pape , Swaddle John P 
Published: November 2023

Abstract
In this chapter we introduce the concepts of homeostasis, canalisation, and developmental stability and how this relates to developmental stress (sections 1.2-3). We then review the ways in which developmental stability has been assessed and measured. These methods include monitoring the frequency of deviant phenotypes (phenodeviants—section 1.4.1) and measuring variation in trait size (coefficient of variation—section 1.4.2) both among and within populations. Both of these methods are limited in that it is not possible to make a priori predictions concerning the true frequency of phenodeviants or the coefficient of variation within and among populations. Therefore the populations under investigation have to be thoroughly sampled to render accurate estimates of developmental stability. These two indices also tend not to control for differences in genotype or environmental variation during development, and so may not be good estimators of developmental stability (section 1.4.3).
The reproductive biology of Australian flying-foxes (genus Pteropus)
Authors: Martin L , Kennedy J H , Little L , Luckhoff H C , O’brien G M , Pow C S T , Towers P A , Waldon A K , Wang D Y 
Published: November 2023

Abstract
Three Australian species of Pteropus occupying tropical to temperate habitats have similar distributions of birth-times. A fourth, P. scapulatus, overlaps the others’ ranges yet breeds six months out of phase. Captive males show annual testicular cycles which shift little between years and are unresponsive (P. scapulatus), or only sluggishly responsive (P. poliocephalus), to altered photoperiod. In the breeding-season, males increase their weight, odour and marking behaviour, copulating repeatedly with intact and ovariectomized females; out of season, copulations occur well into pregnancy. Females are not simple reflex ovulators. Lactation does not delay conception. Corpora lutea do not persist to the next pregnancy and there is no strong evidence for ovulation alternating between ovaries. Female P. poliocephalus exposed prematurely to short photoperiod do not conceive early, but females isolated until after the breeding season conceive and give birth late. With no evidence of delayed embryo implantation or development, natural late births probably reflect late conceptions. Endocrine regulation of ovulation remains enigmatic. There are no useful markers of ovarian function, peripheral progesterone levels are anomalous and endometrial growth associated with the preovulatory follicle is confined to the ipsilateral horn.
Constraint and flexibility-bats as predators, bats as prey
Authors: FENTON M Brock 
Published: November 2023

Abstract
Viewed as predators or as prey, bats offer excellent examples of how constraints on performance are ameliorated by behavioural flexibility. Bats hunting airborne targets often eat different things to those taking prey from surfaces. These behavioural differences determine prey species and hence energetic input per prey item. Limitations translate less directly to dietary differences when similar species are compared. Flexi bility often means exploiting concentrations of prey, such as the insects around lights, but can include different hunting behaviours and patterns of habitat use. Heterothermy, the ability to reduce body temperatures, is another facet of flexibility only available to some bats. The echolocation calls of bats function as releasers for defensive behaviour by some insects, affecting the bats’ hunting success. Some arctiid moths further affect bat hunting by producing clicking sounds as they are attacked. Some bats circumvent hearing-based insect defences by producing quiet, short echolocation calls or using other cues to find their prey. The same blend of constraints and flexibility is shown by some predators of bats. For diurnal raptors, light levels and feeding behaviour limit intake of bats. Bats emerging from roosts show behaviour patterns predicted by the selfish herd principle.
Information transfer in bats
Authors: Wilkinson Gerald S 
Published: November 2023

Abstract
Here I review, and present new, evidence indicating that bats gain information about their environment, i.e. the location or quality of food, roosting sites, predators or mates, from other bats. Four mechanisms-local enhancement, social facilitation, imitative learning, and intentional signalling-of acquiring or transmitting infor mation are described. Local enhancement or inad;ertent direction to a resource has been demonstrated for two situations-eavesdropping and following. Playback experiments with several species show that insectivorous bats approach echolocation calls. Non-random departures from nursery colonies have been described for several species; in Nycticeius humeralis individuals improve their foraging success by following previously successful foragers to feeding sites. Social facilitation may occur in at least one group-foraging species where per capita feeding attempts increase with group size. Imitative learning has been reported for several species learning to feed under novel situations in the laboratory, but the data are consistent with local enhancement and individual learning. Matching of echolocation call frequency in one species provides the best evidence for imitative learning, while matching of isolation calls to directive calls may simply reflect heritable ontogenetic change.
LC-UV-MS: a powerful approach for the rapid screening of metabolites in crude plant extracts
Authors: Wolfender Jean-Luc , Hostettmann Kurt 
Published: November 2023

Abstract
When working with medicinal plants, the main goal is to isolate and identify constituents showing interesting biological properties. Generally, bioactivity-guided fractionation of the plant extracts is performed leading to the isolation and identification of the active compounds (Hamburger and Hostettmann 1991). However, this procedure is time consuming and sometimes the active metabolites can be plant constituents already well known. Furthermore, the number of simple bioassays available in phytochemical laboratories is rather limited, giving only a partial idea of the potential activities of a crude plant extract. Thus, many interesting natural products are missed by such a limited biological screening. In order to improve this procedure, a complementary approach is needed, consisting of a chemical screening of the extracts. To perform this screening, a multidimensional approach involving hyphenated techniques such as liquid chromatography coupled with photodiode array detection (LC-UV), with mass spectrometry (LC-MS), or with tandem mass spectrometry (LC-MS/MS) have been used. Indeed LC-UV-MS gives important structural information on plant metabolites, on-line, rapidly, and with a minute amount of plant sample material. These on-line UV and MS data, together with chemotaxonomical considerations, allow an early recognition of common natural products, avoiding their time-consuming isolation. Furthermore, an efficient localization of interesting new leads can be performed.
Controlling the differentiation of mouse ES cells in vitro
Authors: Wiles Michael V , Proetzel Gabriele 
Published: November 2023

Abstract
In this chapter we outline the concepts and practical considerations in understanding and developing defined culture systems for the controlled in vitrodifferentiation of mouse embryonic stem (mES) cells. When looking at the history of mES-cell in vitrodifferentiation, one is struck by the level of alchemy that was introduced, and at times still is used, to obtain desired cell types. However, a fundamental difference between alchemy and science is that science is based on understanding; in designing ES-cell differentiation experiments it is essential that we have a total grasp of the question, and use reagents that are defined and reliable. In examining the differentiation of ES cells into specific, differentiated cell types we must define the system by using reagents that allow interpretation of the results and, equally important, ensure reproducibility. Ideas can thus be proposed and tested, data interpreted, and the information used by others to extend the work. It is only by progressing from alchemy to science that the full potential of ES cells can be exploited and developed coherently.
Paul P. Ewald and the building of the crystallographic community
Authors: Kamminga Harmke 
Published: November 2023

Abstract
Besides contributing in fundamental ways to the theory of propagation of X-rays in crystals, Paul Ewald was instrumental in consolidating the social cohesion of the international crystallographic community. This has been a diverse community since the beginnings of X-ray crystallography, comprising those concerned with the physical foundations of X-ray diffraction phenomena, those involved in developing methods of crystal structure analysis, and those engaged in crystal structure determination for the sake of its value to a range of established disciplines, from mineralogy and chemistry to metallurgy and biology. A specialized area that has close links with such a variety of fields of scientific enquiry might well have fragmented, were it not for the efforts of a number of leading figures within X-ray crystallography to stress the common problems and interests of this diverse community as a whole.
The So-Called Correction of Bragg’s Law
Authors: Ewald By P P 
Published: November 2023

Abstract
The traditional ‘correction of Bragg’s law’ is discussed for any value of the refractive index of the diffracting medium. The finite angular range of reflection, as given by the dynamical theory of interference, is symmetrical about the corrected Bragg glancing angle only if absorption can be neglected. In this case the centroid of the reflected intensity is given by the corrected Bragg law. When absorption has to be taken into account or when, besides the surface-reflected ray, other strong diffracted rays occur inside the crystal, the simple corrected law is not sufficient. For spectroscopic work of precision equal to that achieved for visible light a careful analysis of the incident X-ray appears necessary concerning its collimation (angular width) and polarization. Furthermore, the setting of the diffracting crystal has to be investigated in order to avoid unwanted simultaneous reflections. The ideal would be to combine a recording of the actual reflection curve with the high-precision absolute measurement of the glancing angle that serves as zero for the reflection curve. This requires novel instrumentation.
Electron Diffraction: An Introduction
Authors: Cowley J M 
Published: November 2023

Abstract
The demonstration of diffraction effects with electrons, by Davisson and Germer (1927) in the low-energy range and by Thomson and Reid (1927) in the higher energy range, served to confirm deBroglie's hypothesis that the electron particles could be guided by waves (see de Broglie, 1981). From this starting point the techniques of electron diffraction have developed as a basis for many types of investigation of the structure of matter. The theoretical assumption made as a basis for most of the developments is that electrons can be described in terms of waves. The wave functions, which are solutions of the Schroedinger wave equation, are effective means for describing the observable intensities.
Diffraction and Imaging in Electron Microscopy
Authors: Cowley J M 
Published: November 2023

Abstract
The interdependence of transmission electron microscopy (TEM), particularly for non-biological applications, and electron diffraction has become an essential component of both techniques. For the imaging of crystalline materials the contrast is strongly dependent on the diffraction conditions so that the recording of the electron diffraction pattern from the imaged area is a important part of the image interpretation. On the other hand, the electron diffraction intensity distributions are so strongly affected by size, shape, thickness and distortion of the diffracting crystals that information on these factors derived from imaging is of great significance. The availability of such information from electron microscopy has been very largely responsible for the advances in understanding of the electron diffraction processes during the last forty years in allowing detailed comparison of theoretical results and experimental observations.
Coherent Convergent Beam Diffraction
Authors: Cowley J M , da Piedade Manuel Minas 
Published: November 2023

Abstract
For most of the CBED applications, carried out in TEM instruments, it is appropriate to assume that the convergent beam incident on the specimen is incoherent. For each incident beam direction the diffraction effects are calculated as if for an incident plane wave; then the intensity distributions for all incident beam direction are added. No consideration is given to the possibility that interference effects may arise between electron waves generated in the sample by scattering from two different directions of incidence. This assumption can be justified by a simple calculation
J
Authors: Atkins P W 
Published: November 2023

Abstract
A Jablonski diagram is a schematic pprtrayal of the relative positions of the electronic and vibrational levels of a molecule without any attempt being made to show the relative geometrical locations in terms of molecular potential energy curves. Even the vibrational levels are represented only schematically. The diagrams currently used are modified versions of those introduced by A. Jablonski in 1935 in his discussion of the mechanism of °phosphorescence.
N
Authors: Atkins P W 
Published: November 2023

Abstract
A node is a point, line, or surface at which a wavefunction is zero and which separates regions of opposite sign of a wavefunction. The Condition that the wavefunction should change sign at a node implies that the points at infinity where ijJ approaches zero are not counted as nodes, nor are the boundaries of a well, at which the wavefunction is zero. As a general rule, the greater the number of nodes in a wavefunction, the higher its energy.
P
Authors: Atkins P W 
Published: November 2023

Abstract
A p orbital is an °atomic orbital with l = 1. An electron in a p orbital is called a p electron, and has an °orbital angular momentum of magnitude 2112h. Each p subshell of an atom consists of three orbitals, corresponding to the three values of m1 (+1, 0, and -1) that are permitted when l= 1. A p orbital has one angular node, which separates the wavefunction into two lobes of opposite sign (Fig. P.1). Since the node passes through the nucleus, there is zero probability of a p electron being found there. In this respect a p orbital differs sharply from an °s orbital, which can be found at the nucleus.
S
Authors: Atkins P W 
Published: November 2023

Abstract
An s orbital is an °atomic orbital with l = 0. An electron in an s orbital is called an s electron. There is one s orbital in each shell of an atom. All s orbitals are spherically symmetrical (with no angular nodes, Fig. S.1) but as the number of radial nodes is equal to n-1, higher shells have progressively more radial nodes (Fig. S.2). All s orbitals have non-zero amplitude at the nucleus; therefore an s electron has a non-zero probability of being found very close to the nucleus. This difference in behaviour from all other atomic orbitals (which have zero amplitude at the nucleus) is a consequence of the s orbital having zero orbital angular momentum, with the result that there is no centrifugal force acting on the electron however closely it approaches the nucleus. That an s electron can °penetrate through inner shells and approach the nucleus closely is of profound importance for the periodicity of the elements and the structure of the periodic table.
T
Authors: Atkins P W 
Published: November 2023

Abstract
A Tanabe-Sugano diagram shows how the energies of the °terms of an atom or ion change as the strength of a °ligand field increases. The diagrams provide a convenient way of analyzing the complicated electronic absorption spectra that are characteristic of d” complexes. The Tanabe-Sugano diagrams for d” ions in an octahedral environment are shown in Fig. T.1. The terms of the free ion are given on the left of the diagram (compare Fig. R.l). Their positions are calculated from the °Racah parameters B and C and plotted as E/B. It is usual to make a plausible assumption about the relative values of B and C (typically, C:::::::4B), for then the energies can be expressed in terms of B alone. The horizontal axis depicts increasing ligand field strength (and is expressed as /1/B, where /1 is the ligand field splitting parameter). The lines emerging from each free-atom term depict what terms they become in an octahedral environment. Thus, a 3F term of a d2 gas phase ion become the three sets of terms 3 A2, 3T1, and 3T2 in the complex.