Quantum Theory of Surface Plasmon Polaritons: Planar and Spherical Geometries

A quantum theory of retarded surface plasmons on a metal–vacuum interface is formulated, by analogy with the well-known and widely exploited theory of exciton-polaritons. The Hamiltonian for mutually interacting instantaneous surface plasmons and transverse electromagnetic modes is diagonalized with recourse to a Hopfield–Bogoljubov transformation, in order to obtain a new family of modes, to be identified with retarded plasmons. The interaction with nearby dipolar emitters is treated with a full quantum formalism based on a general definition of modal effective volumes. The illustrative cases of a planar surface and of a spherical nanoparticle are considered in detail. In the ideal situation of absence of dissipation, as an effect of the conservation of in-plane wavevector, retarded plasmons on a planar surface represent true stationary states (which are usually called surface plasmon polaritons), whereas retarded plasmons in a spherical nanoparticle, characterized by frequencies that overlap with the transverse electromagnetic continuum, become resonances with a finite radiative broadening. The theory presented constitutes a suitable full quantum framework for the study of nonperturbative and nonlinear effects in plasmonic nanosystems.     

A dark business,full of shadows: Analogy and theology in William Harvey

In a short work called De conceptione appended to the end of his Exercitationes de generatione animalium (1651), William Harvey developed a rather strange analogy. To explain how such marvelous productions as living beings were generated from the rather inauspicious ingredients of animal reproduction, Harvey argued that conception in the womb was like conception in the brain. It was mostly rejected at the time; it now seems a ludicrous theory based upon homonymy. However, this analogy offers insight into the structure and function of analogies in early modern natural philosophy. In this essay I hope to not only describe the complex nature of Harvey’s analogy, but also offer a novel interpretation of his use of analogical reasoning, substantially revising the account offered by Guido Giglioni (1993). I discuss two points of conceptual change and negotiation in connection with Harvey’s analogy, understanding it as both a confrontation between the border of the natural and the supernatural, as well as a moment in the history of psychology. My interpretation touches upon a number of important aspects, including why the analogy was rejected, how Harvey systematically deployed analogies according to his notions of natural philosophical method, how the analogy fits into contemporary discussions of analogies in science, and finally, how the analogy must be seen in the context of changing Renaissance notions of the science of the soul, ultimately confronting the problem of how to understand final causality in Aristotelian science. In connection with the last, I conclude the essay by turning to how Harvey embeds the analogy within a natural theological cosmology.     

Social evolution and strategic thinking

Thinking about organisms as if they were rational agents which could choose their own phenotypic traits according to their fitness values is a common heuristic in the field of evolutionary theory. In a 1998 paper, however, Elliott Sober has emphasized several alleged shortcomings of this kind of analogical reasoning when applied to the analysis of social behaviors. According to him, the main flaw of this heuristic is that it proves to be a misleading tool when it is used for predicting the evolution of cooperation. Here, I show that these charges raised against the heuristic use of this analogy are misguided. I argue, contra Sober, that such a heuristic turns out to be a perfect predictive tool in all relevant contexts where cooperation can at least evolve. Moreover, I argue that it constitutes a powerful and sufficient methodological framework for the analysis of social evolution.     

Arguing by analogy in the fetal tissue debate

In the debate over fetal tissue use, an analogy is often drawn between removing organs from the body of a person who has been murdered to use for transplantation, and collecting tissue from an aborted fetus to use for the same purpose. The murder victim analogy is taken by its proponents to show that even if abortion is the moral equivalent of murder, there is still no good reason to refrain from using the fetal tissue, since as a society we do not see any problem about using organs from murder victims. However, I argue that the analogy between murder victims and aborted fetuses does not hold — the two situations are not the same in all morally relevant respects. Thus the murder victim analogy does not provide an argument in favour of fetal tissue transplant. In conclusion, I point to some of the potential pitfalls of using analogies in ethical argument.     

The notion of gift-giving and organ donation

The analogy between gift-giving and organ donation was first suggested at the beginning of the transplantation era, when policy makers and legislators were promoting voluntary organ donation as the preferred procurement procedure. It was believed that the practice of gift-giving had some features which were also thought to be necessary to ensure that an organ procurement procedure would be morally acceptable, namely voluntarism and altruism. Twenty-five years later, the analogy between gift-giving and organ donation is still being made in the literature and used in organ donation awareness campaigns. In this paper I want to challenge this analogy. By examining a range of circumstances in which gift-giving occurs, I argue that the significant differences between the various types of gift-giving and organ donation makes any analogy between the two very general and superficial, and I suggest that a more appropriate analogy can be found elsewhere.     

Darwin and His Pigeons. The Analogy Between Artificial and Natural Selection Revisited

The analogy between artificial selection of domestic varieties and natural selection in nature was a vital element of Darwin’s argument in his Origin of Species. Ever since, the image of breeders creating new varieties by artificial selection has served as a convincing illustration of how the theory works. In this paper I argue that we need to reconsider our understanding of Darwin’s analogy. Contrary to what is often assumed, nineteenth-century animal breeding practices constituted a highly controversial field that was fraught with difficulties. It was only with considerable effort that Darwin forged his analogy, and he only succeeded by downplaying the importance of two other breeding techniques – crossing of varieties and inbreeding – that many breeders deemed essential to obtain new varieties. Part of the explanation for Darwin’s gloss on breeding practices, I shall argue, was that the methods of his main informants, the breeders of fancy pigeons, were not representative of what went on in the breeding world at large. Darwin seems to have been eager to take the pigeon fanciers at their word, however, as it was only their methods that provided him with the perfect analogy with natural selection. Thus while his studies of domestic varieties were important for the development of the concept of natural selection, the reverse was also true: Darwin’s comprehension of breeding practices was moulded by his understanding of the working of natural selection in nature. Historical studies of domestic breeding practices in the eighteenth and nineteenth century confirm that, besides selection, the techniques of inbreeding and crossing were much more important than Darwin’s interpretation allowed for. And they still are today. This calls for a reconsideration of the pedagogic use of Darwin’s analogy too.     

Ruse's Darwinian meta-ethics: A critique

Michael Ruse, in Taking Darwin Seriously seeks to establish that taking Darwin seriously requires us to treat morality as subjective and naturalistic. I argue that, if morality is not objective, then we have no good reason for being moral if we can avoid detection and punishment. As a consequence, we will only continue to behave morally as long as we remain ignorant of Ruse's theory, that is, as long as the cat is not let out of the bag. Ruse offers a number of arguments to show that his theory can overcome such problems. I argue that they all fail. Ruse also argues that he can offer a naturalistic account of ethics which steps around the naturalistic fallacy and avoids the confusion of reasons with causes. His principal argument for this view is an analogy between spiritualism and morality. I argue that this analogy fails.     

The size of spherical virus capsomeres

The maximum size of the capsomeres of a spherical virus is discussed in the light of an analogy between this virus problem and the mathematical problem of placing equal nonoverlapping circles on a sphere.     

Genetic drift as a directional factor: biasing effects and a priori predictions

The adequacy of Elliott Sober’s analogy between classical mechanics and evolutionary theory—according to which both theories explain via a zero-force law and a set of forces that alter the zero-force state—has been criticized from various points of view. I focus here on McShea and Brandon’s claim that drift shouldn’t be considered a force because it is not directional. I argue that there are a number of different theses that could be meant by this, and show that one of those theses—the idea that drift cannot bias populations to be taken somewhere in the evolutionary space from one generation to the next—is actually false. Not only has this thesis been implicitly assumed in the discussion of the force analogy thus far, but it is also commonly found in a wider range of philosophical and biological texts. I argue that correcting this view, and the usual images associated with it, will thereby bring heuristic benefits that impact the force analogy discussion, but that also go beyond it.     

Darwin, Herschel, and the role of analogy in Darwin’s origin

In what follows, I consider the role of analogy in the first edition of Darwin’s Origin. I argue that Darwin follows Herschel’s methodology and hence exploits an analogy between artificial and natural selection that allows him generalize selection as a cause of evolutionary change. This argument strategy is not equivalent to an argument from analogy. Reading Darwin’s argument as conforming to Herschel’s two-step methodology of causal analysis followed by generalization allows us to understand the role and placement of Darwin’s discussion of artificial selection in the Origin, without making the mistake of portraying Darwin’s argument for the existence and character of natural selection as an analogical argument.     

At the Margins of Moral Personhood

In this article I examine the proposition that severe cognitive disability is an impediment to moral personhood. Moral personhood, as I understand it here, is articulated in the work of Jeff McMahan as that which confers a special moral status on a person. I rehearse the metaphysical arguments about the nature of personhood that ground McMahan’s claims regarding the moral status of the “congenitally severely mentally retarded” (CSMR for short). These claims, I argue, rest on the view that only intrinsic psychological capacities are relevant to moral personhood: that is, that relational properties are generally not relevant. In addition, McMahan depends on an argument that species membership is irrelevant for moral consideration and a contention that privileging species membership is equivalent to a virulent nationalism (these will be discussed below). In consequence, the CSMR are excluded from moral personhood and their deaths are less significant as their killing is less wrong than that of persons. To throw doubt on McMahan’s conclusions about the moral status and wrongness of killing the CSMR I question the exclusive use of intrinsic properties in the metaphysics of personhood, the dismissal of the moral importance of species membership, and the example of virulent nationalism as an apt analogy. I also have a lot to say about McMahan’s empirical assumptions about the CSMR.     

Can biology make ethics objective?

A familiar position regarding the evolution of ethics is that biology can explain the origin of morals but that in doing so it removes the possibility of their having objective justification. This position is set fourth in detail in the writings of Michael Ruse (1986, 1987, 1989, 1990a, 1990b) but it is also taken by many others, notably, Jeffrie Murphy (1982), Andrew Oldenquist (1990), and Allan Gibbard (1990), I argue the contrary view that biology provides a justification of the existence of morals which is objective in the sense of being independent of people's moral views and their particular desires and preferences. Ironically, my argument builds on the very premises which are supposed to undermine the objectivity of morals. But my argument stops short of claiming that biology can give us a basis for justifying some particular system of morals. Drawing on an analogy with social contract theory, I offer a general reason why this more ambitious project cannot be expected to succeed if the argument is pursued along the same lines. Finally, I give reasons why the possibility of objective justification for a particular morality cannot be ruled out in general on evolutionary grounds.     

Theoretical examination of aggregation effect on the dielectric characteristics of spherical cellular suspension

Dielectric dispersion analysis of cellular suspension is generally based on the analogy to equivalent periodic material made up of identical inclusions. However, under true physiological conditions, when coupling and aggregation events usually occur, this analogy can introduce severe errors when attempting to probe the dielectric characteristics of the suspended fraction. In the framework of this study, a theoretical examination of the effect of aggregation on the dielectric characteristics of spherical cellular suspension is presented. Here, small clusters of coupled and fused (gap connected) shelled spheres were used to imitate the presence of aggregates when suspended in a homogenous suspension of spherical cells. The permittivity spectra of the aggregate-cell mixtures were numerically calculated by applying computational solution of complex potential problem using 3D Boundary Element Method. The dispersion characteristics of the mixtures have been determined as function of both aggregates shape and concentration. Those reveal significant deviations in comparison to the characteristics of homogenous cellular suspension. Quantitative analyses of the induced fields and transmembrane potential gradients of the interacted cells suggest that those deviations are mainly induced due to changes occur on the polarization state of the membranes.     

Analogies in science and science teaching

Analogies are often used in science, but students may not appreciate their significance, and so the analogies can be misunderstood or discounted. For this reason, educationalists often express concern about the use of analogies in teaching. Given the important place of analogies in the discourse of science, it is necessary that students are explicitly shown how they work, perhaps based on the structure-mapping theory we outline here. When using an analogy, the teacher should very clearly specify both its components and its limitations. Great care is required in developing an analogy to ensure that it is understood as intended and that misconceptions are minimized. This approach models the behavior of a scientist, which helps to develop student understanding of the practice of science.     

Social Relations and the Green Critique of Capitalism in Melanesia

ABSTRACT  In this article, I explore what a critical environmental perspective would look like in Melanesia, where the distinction between nature and culture, and the expectation that science interprets the former in terms of the latter, may not apply. I consider changes in scientific knowledge production and the shift from cultural ecology to political ecology in Melanesian anthropology, including the argument that Melanesians are neither conservationists nor environmentalists. In contrast, I show how people exposed to pollution from the Ok Tedi copper and gold mine in Papua New Guinea mobilize their understandings of difference in a green critique of capitalism. I examine a strategy session of local activists, a public meeting about their campaign against the mine, and a sorcery tribunal. Finally, I suggest that Melanesian ideas about social relations provide a useful ethnographic analogy for thinking about the mobility and short temporal horizons of contemporary capitalism.     

A model for understanding membrane potential using springs

In this report, I present a simple model using springs to conceptualize the relationship between ionic conductances across a cellular membrane and their effect on membrane potential. The equation describing the relationships linking membrane potential, ionic equilibrium potential, and ionic conductance is of similar form to that describing the force generated by a spring as a function of its displacement. The spring analogy is especially useful in helping students to conceptualize the effects of multiple conductances on membrane potential.     

A reinvestigation of inhibitors of glyoxalase I

It has been reported earlier that nucleotides, nucleosides and a series of structurally related compounds as well as compounds based on transition state analogy inhibit yeast glyoxalase I. In our study on the metabolic regulation of glyoxalase I, we have found that nucleotides such as ATP, GTP and different classes of other reagents based on transition state analogy (D-isoascorbate, dihydroxyfumaric acid, rhodizonic acid) do not inhibit yeast or goat liver glyoxalase I. The reported inhibition of glyoxalase I by these compounds has been found to be due to the interference of these compounds with the absorbancy at 240 nm of S-D-lactoylglutathione formed by the glyoxalase I reaction. Glyoxalase I from goat liver has been found to be strongly and competitively inhibited by lactaldehyde. But, lactaldehyde has very little inhibitory effect on yeast glyoxalase I. Lactaldehyde is formed from methylglyoxal, the substrate for glyoxalase I by the enzyme methylglyoxal reductase. D-Lactaldehyde inhibits the liver enzyme more strongly than L-lactaldehyde.     

Carbonic anhydrase subunits form a matrix-exposed domain attached to the membrane arm of mitochondrial complex I in plants

Complex I of Arabidopsis includes five structurally related subunits representing gamma-type carbonic anhydrases termed CA1, CA2, CA3, CAL1, and CAL2. The position of these subunits within complex I was investigated. Direct analysis of isolated subcomplexes of complex I by liquid chromatography linked to tandem mass spectrometry allowed the assignment of the CA subunits to the membrane arm of complex I. Carbonate extraction experiments revealed that CA2 is an integral membrane protein that is protected upon protease treatment of isolated mitoplasts, indicating a location on the matrix-exposed side of the complex. A structural characterization by single particle electron microscopy of complex I from the green alga Polytomella and a previous analysis from Arabidopsis indicate a plant-specific spherical extra-domain of about 60 A in diameter, which is attached to the central part of the membrane arm of complex I on its matrix face. This spherical domain is proposed to contain a heterotrimer of three CA subunits, which are anchored with their C termini to the hydrophobic arm of complex I. Functional implications of the complex I-integrated CA subunits are discussed.