Why Be regular?, part I

We provide a novel perspective on “regularity” as a property of representations of the Weyl algebra. We first critique a proposal by Halvorson [2004, “Complementarity of representations in quantum mechanics”, Studies in History and Philosophy of Modern Physics 35 (1), pp. 45–56], who argues that the non-regular “position” and “momentum” representations of the Weyl algebra demonstrate that a quantum mechanical particle can have definite values for position or momentum, contrary to a widespread view. We show that there are obstacles to such an intepretation of non-regular representations. In Part II, we propose a justification for focusing on regular representations, pace Halvorson, by drawing on algebraic methods.     

Why isPyrrhocoris apterus insensitive to precocene II?

Summary Precocene II (P II) was applied to the adult females of 2 Pyrrhocorid bugs —Pyrrhocoris apterus (insensitive to P II) andDysdercus cingulatus (sensitive to P II)-subjected to allatectomy and intraspecific or interspecific reimplantations of corpus allatum (CA). The failure of P II to inhibit ovarian development inP. apterus appears to be caused by both a low sensitivity to P II of the CA itself and unknown anti-precocene mechanisms outside the CA.Precocene II was kindly supplied by Zoecon.     

Why eliminativism?

A central thesis of Steven French's brand of ontic structural realism has always been his eliminativism about objects. Unsurprisingly, this bold and controversial thesis has seen a lot of critical discussion. In his book The Structure of the World—Metaphysics & Representation, French accordingly defends this thesis against a range of challenges. A novel feature of this defense is the use of dependence relations to articulate his eliminativism. In this paper I take a critical look at French's defense of eliminativism and argue that the dependence relations invoked do not eliminate objects.     

Why do hormone receptors arise?

Conclusions In view of the foregoing considerations, it appears that the receptor-hormone relationship is, by origin, essentially a cell-environment (chemical) relationship which influences cell behavior. With the development of multicellularity, the interests of the single (individual) cell became subordinated to those of the cell population (community), and the cell-environment relationship became modified inasmuch as receptor activity became integrated into the functional program of the entire organism. Accordingly, the open program of the individual cell, which involved continuous dynamic changes of the membrane receptors under the influence of the signal molecules, was superseded by a closed program for the given receptor, which gave rise to a chemical memory of the cell. With multicellularity the cellular functions have become integrated into an almost entirely predetermined program in which the quality and operation of the receptors are encoded to maintain the system of regulation, and impart differentiating features to given types of target cells which distinguish them from others, and delimit the response potentials of the species. A limited openness of the pre-programed system exists in the early stage of ontogenesis, and accounts for certain individual variations within the limited potentials of the species.The answer to the question posed in the title of this paper is therefore the following: the hormone receptors arise because the external environment of the individual cell is transformed at the multicellular level to an internal environment, in which the random variety of environmental molecules is replaced by a predetermined set of ligands (signal molecules). Under these conditions the randomlypresented membrane patterns capable of signal reception are transformed to encoded receptor structures which execute a programed function of the closed system, but nevertheless preserve some primordial traits, which can explain many surprising observations in the field of receptor physiology.The Editors wish to thank Professor G. Csaba for having designed and coordinated this review.     

The Archaean controversy in Britain: Part II—The Malverns and Shropshire

An account is given of early geological researches in the Malverns, the Church Stretton area, and the Wrekin. The reconnaissance work of Murchison suggested that each of these areas had Silurian sediments, intruded by igneous rocks (called trap or syenite). The early Survey maps were compiled on this theoretical basis, with the result that the Silurian sediments were regarded as the oldest rocks in Shropshire and the Malverns. Local geologists, working in the three areas, and with sufficient time to study the exposures in detail, began to develop the idea of ‘islands’ of Precambrian (Archaean) rock (perhaps showing some stratification), having younger sediments deposited thereon. This Archaean model was taken up and actively developed, and the stratigraphical details worked out, with the island model being gradually modified. Debates were stronger between members of the ‘Archaean’ fraternity than with the Survey. Traces of trilobite remains were found by Callaway at Comley, near Caer Caradoc, and were identified by Lapworth as Olenellus, enabling the underlying Wrekin Quartzite to be established as the base of the Cambrian, in agreement with ideas developed in North America and Scandinavia. Arguments are detailed concerning the relative ages of the ‘Uriconian’ and ‘Longmyndian’ rocks, and their constituent units. Both were agreed to be Precambrian, but the evidence in terms of field mapping, in relation to the Wrekin Quartzite, is not complete. The problems of stratigraphical work in unfossiliferous rocks are displayed, and also the efforts to achieve correlations with areas such as Pembrokeshire and Anglesey are described. Though consensus has been reached on the Precambrian status of the Malvernian, Uriconian and Longmyndian rocks, radiometric age determinations and other evidence throw doubt on some aspects of the consensus, and research continues.     

Why do funding agencies favor hypothesis testing?

Exploratory inquiry has difficulty attracting research funding because funding agencies have little sense of how to detect good science in exploratory contexts. After documenting and explaining the focus on hypothesis testing among a variety of institutions responsible for distinguishing between good and bad science, I analyze the NIH grant review process. I argue that a good explanation for the focus on hypothesis testing—at least at the level of science funding agencies—is the fact that hypothesis-driven research is relatively easy to appraise. I then explore one method by which we might gauge the epistemic merits of different styles of inquiry.     

Why does the Chinese public accept evolution?

A substantial proportion of Chinese nationals seem to accept evolution, and the country is sometimes held up to show that the sorry state of evolution acceptance in the United States is not inevitable. Attempts to improve evolution acceptance generally focus on improving communication, curricular reform, and even identifying cognitive mechanisms that bias people against evolution. What is it that the Chinese scientific community did so well, and can it be generalized? This paper argues that evolution acceptance in China has a very specific history, one that other countries are very unlikely to emulate. We show that the interactions among science, education, mass media, social and political movements, and ideological arguments about evolution greatly influenced the Chinese public's understanding and acceptance of evolution. We find that it was not just formal education, but many more ideologically motivated methods of evolution exposure that contributed to the high rate of acceptance. But since the purpose of evolution dissemination has moved beyond merely teaching biology, the Chinese public persists with substantial misunderstandings of the theory. Thus, bottom line percentage of acceptance figures can be misleading; the details and the history really matter.     

Can Bohmian mechanics be made background independent?

The paper presents an inquiry into the question regarding the compatibility of Bohmian mechanics, intended as a non-local theory of moving point-like particles, with background independence. This issue is worth being investigated because, if the Bohmian framework has to be of some help in developing new physics, it has to be compatible with the most well-established traits of modern physics, background independence being one of such traits. The paper highlights the fact that the notion of background independence in the context of spacetime physics is slippery and interpretation-laden. It is then suggested that the best-matching framework developed by Julian Barbour might provide a robust enough meaning of background independence. The structure of Bohmian dynamics is evaluated against this framework, reaching some intermediate results that speak in favor of the fact that Bohmian mechanics can be made background independent.     

Would two dimensions be world enough for spacetime?

We consider various curious features of general relativity, and relativistic field theory, in two spacetime dimensions. In particular, we discuss: the vanishing of the Einstein tensor; the failure of an initial-value formulation for vacuum spacetimes; the status of singularity theorems; the non-existence of a Newtonian limit; the status of the cosmological constant; and the character of matter fields, including perfect fluids and electromagnetic fields. We conclude with a discussion of what constrains our understanding of physics in different dimensions.     

Why do regime‐switching models forecast so badly?

Most non‐linear techniques give good in‐sample fits to exchange rate data but are usually outperformed by random walks or random walks with drift when used for out‐of‐sample forecasting. In the case of regime‐switching models it is possible to understand why forecasts based on the true model can have higher mean squared error than those of a random walk or random walk with drift. In this paper we provide some analytical results for the case of a simple switching model, the segmented trend model. It requires only a small misclassification, when forecasting which regime the world will be in, to lose any advantage from knowing the correct model specification. To illustrate this we discuss some results for the DM/dollar exchange rate. We conjecture that the forecasting result is more general and describes limitations to the use of switching models for forecasting. This result has two implications. First, it questions the leading role of the random walk hypothesis for the spot exchange rate. Second, it suggests that the mean square error is not an appropriate way to evaluate forecast performance for non‐linear models. Copyright © 1999 John Wiley & Sons, Ltd.     

EXORCIST XIV: The Wrath of Maxwell’s Demon. Part II. From Szilard to Landauer and Beyond

In this second part of our two-part paper we review and analyse attempts since 1950 to use information theoretic notions to exorcise Maxwell’s Demon. We argue through a simple dilemma that these attempted exorcisms are ineffective, whether they follow Szilard in seeking a compensating entropy cost in information acquisition or Landauer in seeking that cost in memory erasure. In so far as the Demon is a thermodynamic system already governed by the Second Law, no further supposition about information and entropy is needed to save the Second Law. In so far as the Demon fails to be such a system, no supposition about the entropy cost of information acquisition and processing can save the Second Law from the Demon.     

To be disordered or not to be disordered: is that still a question for proteins in the cell?

There is ample evidence that many proteins or regions of proteins lack a well-defined folded structure under native-like conditions. These are called intrinsically disordered proteins (IDPs) or intrinsically disordered regions (IDRs). Whether this intrinsic disorder is also their main structural characteristic in living cells has been a matter of intense debate. The structural analysis of IDPs became an important challenge also because of their involvement in a plethora of human diseases, which made IDPs attractive targets for therapeutic development. Therefore, biophysical approaches are increasingly being employed to probe the structural and dynamical state of proteins, not only in isolation in a test tube, but also in a complex biological environment and even within intact cells. Here, we survey direct and indirect evidence that structural disorder is in fact the physiological state of many proteins in the proteome. The paradigmatic case of α-synuclein is used to illustrate the controversial nature of this topic.     

Can the sulphur bridge be considered as a relay of conjugation?

Riassunto Vengono studiati gli spettri di assorbimento u.v. del nitro-difenil-, nitro-fenil-benzil-solfuro e loro derivati X-sostituiti: dove X è eguale ad NH₂, N(CH₃)₂, OH, OCH₃ in posizione para- o meta- nel fenile non nitro-sostituito rispetto allo zolfo.Viene dimostrato che una coniugazione che si estenda da un fenile all'altro, attraverso il ponte di zolfo nella serie dei difenil-solfuri non è suffragata dai fatti spettroscopici.     

Why was M. S. Tswett’s chromatographic adsorption analysis rejected?

The present paper claims that M. S. Tswett’s chromatographic adsorption analysis, which today is a ubiquitous and instrumentally sophisticated chemical technique, was either ignored or outright rejected by chemists and botanists in the first three decades of the twentieth century because it did not make sense in terms of accepted chemical theory or practice. Evidence for this claim is culled from consideration of the botanical and chemical context of Tswett’s technique as well as an analysis of the protracted debate over Tswett’s chromatographic analysis of chlorophyll between him and Leon Marchlewski, a noted chlorophyll chemist of the period. In this way, the paper expands and amends what it calls the ‘textbook story’ of the early history of chromatography, examples of which may be found in historical notes in many textbooks of chemical instrumental analysis and numerous short articles in chemistry journals. The paper also provides an accessible introduction to the early history of chromatography for historians of science likely to know little or nothing about it.     

Why do EMD‐based methods improve prediction? A multiscale complexity perspective

Empirical mode decomposition (EMD)‐based ensemble methods have become increasingly popular in the research field of forecasting, substantially enhancing prediction accuracy. The key factor in this type of method is the multiscale decomposition that immensely mitigates modeling complexity. Accordingly, this study probes this factor and makes further innovations from a new perspective of multiscale complexity. In particular, this study quantitatively investigates the relationship between the decomposition performance and prediction accuracy, thereby developing (1) a novel multiscale complexity measurement (for evaluating multiscale decomposition), (2) a novel optimized EMD (OEMD) (considering multiscale complexity), and (3) a novel OEMD‐based forecasting methodology (using the proposed OEMD in multiscale analysis). With crude oil and natural gas prices as samples, the empirical study statistically indicates that the forecasting capability of EMD‐based methods is highly reliant on the decomposition performance; accordingly, the proposed OEMD‐based methods considering multiscale complexity significantly outperform the benchmarks based on typical EMDs in prediction accuracy.     

Novel therapy for myocardial infarction: can HGF/Met be beneficial?

Myocardial infarction (MI) is a leading cause of hospitalization worldwide. A recently developed strategy to improve the management of MI is based on the use of growth factors which are able to enhance the intrinsic capacity of the heart to repair itself or regenerate after damage. Among others, hepatocyte growth factor (HGF) has been proposed as a modulator of cardiac repair of damage due to the pleiotropic effects elicited by Met receptor stimulation. In this review we describe the mechanistic basis for autocrine and paracrine protection of HGF in the injured heart. We also analyse the role of HGF/Met in stem cell maintenance and in stem cell therapies for MI. Finally, we summarize the most significant results on the use of HGF in experimental models of heart injury and discuss the potential of the molecule for treating ischaemic heart disease in humans.