Effect of the polychlorinated biphenyl preparation,Aroclor 1242, on the quantity of neurosecretory material in the medulla terminalis X-organ of the fiddler crab,Uca pugilator

Summary Exposure of the fiddler crab,Uca pugilator, to the PCB preparation, Aroclor 1242, produces an increase in the quantity of neurosecretory material in the medulla terminalis X-organ. This Aroclor apparently inhibits release, but not synthesis, of one or more neurohormones.This investigation was supported by grant PCM75-03029 A01 from the National Science Foundation.     

In vivo inhibition of citrate cleavage enzyme by polychlorinated biphenyls

Summary Polychlorinated biphenyls (Aroclor 1254, PCB) administered in the diet (0.01%, w/v) to rats inhibited citrate cleavage enzyme. The results suggest that the decreased activity might in part account for decreased fatty acid synthesis in the livers of PCB-treated rats.This research was supported by a grant from the National Institutes of Health (ES-00040). Aroclor 1254 was a gift of Monsanto Company, St. Louis, Missouri, USA.     

Polychlorinated biphenyl-induced modification of lymphocyte response to plant mitogens in rats

Summary In PCB-treated rats total white cell and differential counts and lymphocyte proliferative response to PWM were unaltered. The lymphocyte response to PHA was increased in treated animals.Acknowledgements. Supported by grants from the Medical Research Council of Canada. We thank the Monsanto Chemical Co., St. Louis, Mo., for donating Aroclor 1254 and Dr.P. Cano for the protein determinations and electrophoresis.     

Effects of the metals,Be, Fe,Cu and Al,on the mobility of immunoglobulin receptors

Summary Cap formation in mouse spleen cells induced by antiimmunoglobulin was inhibited by the metals Be, Fe, Cu and Al. Be was especially strong as an inhibitor of cap formation. It is suggested that these metals might change the mobility of the membrane and have some biological effects on the cross association of antigen receptors when B lymphocytes are attached by them.     

Aristotle, Copernicus, Bruno: centrality, the principle of movement and the extension of the Universe

This paper¹ studies the different conceptions of both centrality and the principle or starting point of motion in the Universe held by Aristotle and later on by Copernicanism until Kepler and Bruno. According to Aristotle, the true centre of the Universe is the sphere of the fixed stars. This is also the starting point of motion. From this point of view, the diurnal motion is the fundamental one. Our analysis gives pride of place to De caelo II, 10, a chapter of Aristotle’s text which curiously allows an ‘Alpetragian’ reading of the transmission of motion.In Copernicus and the Copernicans, natural centrality is identified with the geometrical centre and, therefore, the Sun is acknowledged as the body through which the Deity acts on the world and it also plays the role of the principle and starting point of cosmic motion. This motion, however, is no longer diurnal motion, but the annual periodical motion of the planets. Within this context, we pose the question of to what extent it is possible to think that, before Kepler, there is a tacit attribution of a dynamic or motive role to the Sun by Copernicus, Rheticus, and Digges.For Bruno, since the Universe is infinite and homogeneous and the relationship of the Deity with it is one of indifferent presence everywhere, the Universe has no absolute centre, for any point is a centre. By the same token, there is no place that enjoys the prerogative of being—as being the seat of God—the motionless principle and starting point of motion.     

Cosmology,particles, and the unity of science

During the last three decades, there has been a growing realization among physicists and cosmologists that the relation between particle physics and cosmology may constitute yet another successful example of the unity of science. However, there are important conceptual problems in the unification of the two disciplines, e.g. in connection with the cosmological constant and the conjecture of inflation. The present article will outline some of these problems, and argue that the victory for the unity of science in the context of cosmology and particle physics is still far from obvious.     

The cosmological constant, the fate of the universe, unimodular gravity, and all that

The cosmological constant is back. Several lines of evidence point to the conclusion that either there is a positive cosmological constant or else the universe is filled with a strange form of matter (“quintessence”) that mimics some of the effects of a positive lambda. This paper investigates the implications of the former possibility. Two senses in which the cosmological constant can be a constant are distinguished: the capital Λ sense in which lambda is a universal constant on a par with the charge of the electron, and the lower case λ sense in which lambda is a humble constant of integration. The latter interpretation has been touted as the means to a solution to various problems in physics. These claims are critically examined with an eye to discerning the implications for philosophy of science and foundations of physics.     

Thermoscopes, thermometers, and the foundations of measurement

Psychologists debate whether mental attributes can be quantified or whether they admit only qualitative comparisons of more and less. Their disagreement is not merely terminological, for it bears upon the permissibility of various statistical techniques. This article contributes to the discussion in two stages. First it explains how temperature, which was originally a qualitative concept, came to occupy its position as an unquestionably quantitative concept (§§1–4). Specifically, it lays out the circumstances in which thermometers, which register quantitative (or cardinal) differences, became distinguishable from thermoscopes, which register merely qualitative (or ordinal) differences. I argue that this distinction became possible thanks to the work of Joseph Black, ca. 1760. Second, the article contends that the model implicit in temperature’s quantitative status offers a better way for thinking about the quantitative status of mental attributes than models from measurement theory (§§5–6).     

On the genesis of the soil mantle of the region of Manaus,Central Amazonia,Brazil

Summary The dynamics of the forest to the north of Manaus is tightly linked to that of the soil. The latosol that covers the plateau, which supports a dense forest, consists from top to bottom of: (a) a brown, clayey organic horizon (0.3 m), (b) a yellow horizon, very rich in clay but permeable (from 0.3 to 4 m), (c) a nodular horizon rich in Al and Fe oxides (from 4 to 9 m), and (d) a horizon which still preserves the sedimentary structures of the parent sandstone, where quartz is intensely dissolved and kaolinite crystallizes in pores. In perfectly flat areas, the clay of the organic horizon is destroyed by acidocomplexolysis, and the dissolved Al is transported vertically by the drainage water. A part of this Al is used to make the gibbsite nodules of horizon (c), and the rest is used to make kaolinite in horizon (d). Because aluminum is thus conserved within any vertical prism, the rate of destruction of horizon (a) is equivalent to the rate of advance of the kaolinization zone into the sediment: the latosol is said to be in equilibrium, the surface remains perfectly flat as it slowly sinks, the quantity of kaolinite increases with time, and the silica released by quartz dissolution in the whole profile is exported by drainage water to the water table. In contrast, near drainage axes, however small initially, the drainage becomes inclined toward the axis. Part of the Al released by acidocomplexolysis of horizon (a) is now exported to rivers, and Al is no longer conserved within any given prism. The rate of advance of the kaolinization zone (d) into the sediment now becomes less than the rate of destruction of horizon (a) and the surface sinks faster than that of the surrounding plateau. After this differential podzolization has gone on long enough, it creates a network of geochemical valleys characterized by convex slopes and bounded by sandy soils (campinas). The vegetation becomes sparser and sparser. At the end, only some bushes and lichens survive on the white sand.Acknowledgments. The authors are indebted to Dr E. Merino (Dept. of Geology, Indiana University) for helpful criticisms and suggestions. This research was carried out in I.N.P.A. (Instituto Nacional de Pesquisas da Amazonia) and was financially supported by the CNPq-CNRS/ORSTOM conv.     

The action of the cholecystokinin-A receptor antagonist,devazepide, on the digestive system of the chicken

The influence of the cholecystokinin (CCK)-A receptor antagonist, devazepide (DVZ), on the chicken digestive tract was investigated. The passage of food from the crops of birds treated with DVZ was not significantly different from that of the control. DVZ treatment did not inhibit the biliary flow stimulated by the CCK analogue, caerulein. Dispersed chicken pancreatic acini stimulated with CCK were treated with various concentrations of DVZ. At 10^–5 M, DVZ completely inhibited amylase release; this concentration was much higher than those reported to have similar effects in mammals. The results suggest that the action DVZ as a CCK antagonist in the chicken is very weak.     

Many worlds,the cluster-state quantum computer,and the problem of the preferred basis

I argue that the many worlds explanation of quantum computation is not licensed by, and in fact is conceptually inferior to, the many worlds interpretation of quantum mechanics from which it is derived. I argue that the many worlds explanation of quantum computation is incompatible with the recently developed cluster state model of quantum computation. Based on these considerations I conclude that we should reject the many worlds explanation of quantum computation.     

Scepticism,relativism, and the structure of epistemic frameworks

This paper has four aims: first, to outline the role of the sceptical problem of the criterion in the principal argument for epistemic relativism; second, to establish that methodist and particularist responses to the problem of the criterion do not, by themselves, constitute successful strategies for resisting epistemic relativism; third, to argue that a more fruitful strategy is to attempt to evaluate epistemic frameworks on the basis of the epistemic resources that they have in common; and finally, to make the case that finding this common ground will necessarily involve determining how it is that a framework’s constituent epistemic methods depend on one another for not only their warrant, but for their application.     

Biosynthesis, immunity, regulation, mode of action and engineering of the model lantibiotic nisin

This review discusses the state-of-the-art in molecular research on the most prominent and widely applied lantibiotic, i.e., nisin. The developments in understanding its complex biosynthesis and mode of action are highlighted. Moreover, novel applications arising from engineering either nisin itself, or from the construction of totally novel dehydrated and/or lanthionine-containing peptides with desired bioactivities are described. Several challenges still exist in understanding the immunity system and the unique multiple reactions occurring on a single substrate molecule, carried out by the dehydratase NisB and the cyclization enzyme NisC. The recent elucidation of the 3-D structure of NisC forms the exciting beginning of further 3-D-structure determinations of the other biosynthetic enzymes, transporters and immunity proteins. Advances in achieving in vitro activities of lanthionine-forming enzymes will greatly enhance our understanding of the molecular characteristics of the biosynthesis process, opening up new avenues for developing unique and novel biocatalytic processes. Received 9 April 2007; received after revision 31 August 2007; accepted 28 September 2007     

Naturalness,the autonomy of scales,and the 125 GeV Higgs

The recent discovery of the Higgs at 125 GeV by the ATLAS and CMS experiments at the LHC has put significant pressure on a principle which has guided much theorizing in high energy physics over the last 40 years, the principle of naturalness. In this paper, I provide an explication of the conceptual foundations and physical significance of the naturalness principle. I argue that the naturalness principle is well-grounded both empirically and in the theoretical structure of effective field theories, and that it was reasonable for physicists to endorse it. Its possible failure to be realized in nature, as suggested by recent LHC data, thus represents an empirical challenge to certain foundational aspects of our understanding of QFT. In particular, I argue that its failure would undermine one class of recent proposals which claim that QFT provides us with a picture of the world as being structured into quasi-autonomous physical domains.     

Melatonin,mitochondria, and the skin

The skin being a protective barrier between external and internal (body) environments has the sensory and adaptive capacity to maintain local and global body homeostasis in response to noxious factors. An important part of the skin response to stress is its ability for melatonin synthesis and subsequent metabolism through the indolic and kynuric pathways. Indeed, melatonin and its metabolites have emerged as indispensable for physiological skin functions and for effective protection of a cutaneous homeostasis from hostile environmental factors. Moreover, they attenuate the pathological processes including carcinogenesis and other hyperproliferative/inflammatory conditions. Interestingly, mitochondria appear to be a central hub of melatonin metabolism in the skin cells. Furthermore, substantial evidence has accumulated on the protective role of the melatonin against ultraviolet radiation and the attendant mitochondrial dysfunction. Melatonin and its metabolites appear to have a modulatory impact on mitochondrion redox and bioenergetic homeostasis, as well as the anti-apoptotic effects. Of note, some metabolites exhibit even greater impact than melatonin alone. Herein, we emphasize that melatonin–mitochondria axis would control integumental functions designed to protect local and perhaps global homeostasis. Given the phylogenetic origin and primordial actions of melatonin, we propose that the melatonin-related mitochondrial functions represent an evolutionary conserved mechanism involved in cellular adaptive response to skin injury and repair.     

Giant collagen fibres in the gonopodium of the mosquitofishHeteradria formosa,Agassiz, 1853 (Pisces,Poeciliidae)

Summary The gonopodium of the mosquitofishHeteradria formosa was studied by transmission electron microscopy. In cross-section the gonopodium shows the following structure from the outside inwards: mutilayered epidermis, basal lamina and central supporting tissue, in which vessels and nerves are embedded. At the top of the gonopodium giant collagen fibres are found, which measure up to 150 m in length and 6 m in diameter. These fibres reinforce the gonopodium.This research was supported by the Deutsche Forschungsgemeinschaft. Address for reprints: Forschungsgruppe Dermatologie der Universität Heidelberg, Im Neuenheimer Feld 324, D-6900 Heidelberg.     

Special cases,composition of causes,and the complexity of nature

It is often held by philosophers of science that special, idealized situations are prior to complex cases in several senses: equations for complex cases are derived from those for special cases by “composing” special case equations; behavior in complex cases is explained in terms of behavior in special cases; one learns the true nature of a property in the special case where it is allowed to work in isolation. In this paper, I argue that a strand of non-equilibrium thermodynamics which attempts to go beyond the limitations of classical non-equilibrium thermodynamics adheres to something that is the reverse of this picture. Thus, the legitimacy (or lack thereof) of this picture lies very near to the heart of foundational issues in non-equilibrium thermodynamics.