A beautiful sea: P. A. M. Dirac's epistemology and ontology of the vacuum

This paper charts P.A.M. Dirac's development of his theory of the electron, and its radical picture of empty space as an almost-full plenum. Dirac's Quantum Electrodynamics famously accomplished more than the unification of special relativity and quantum mechanics. It also accounted for the ‘duplexity phenomena’ of spectral line splitting that we now attribute to electron spin. But the extra mathematical terms that allowed for spin were not alone, and this paper charts Dirac's struggle to ignore or account for them as a sea of strange, negative-energy, particles with positive ‘holes’. This work was not done in solitude, but rather in exchanges with Dirac's correspondence network. This social context for Dirac’s work contests his image as a lone genius, and documents a community wrestling with the ontological consequences of their work. Unification, consistency, causality, and community are common factors in explanations in the history of physics. This paper argues on the basis of materials in Dirac's archive that --- in addition --- mathematical beauty was an epistemological factor in the development of the electron and hole theory. In fact, if we believe that Dirac's beautiful mathematics captures something of the world, then there is both an epistemology and an ontology of mathematical beauty.     

Forecasts and expectations: Some evidence for the U.K.

Forecasts from econometric models have been given a lot of publicity in the U.K. This paper examines the performance of five major models in forecasting inflation and the rate of growth. Two types of forecast are considered: the annual pre-budget ones and a quarterly series. It is suggested that public forecasts provide a cheap method of implementing economically rational expectations.     

Instruments and rules: R. B. Woodward and the tools of twentieth-century organic chemistry

The paper illustrates how organic chemists dramatically altered their practices in the middle part of the twentieth century through the adoption of analytical instrumentation — such as ultraviolet and infrared absorption spectroscopy and nuclear magnetic resonance spectroscopy — through which the difficult process of structure determination for small molecules became routine. Changes in practice were manifested in two ways: in the use of these instruments in the development of ‘rule-based’ theories; and in an increased focus on synthesis, at the expense of chemical analysis. These rule-based theories took the form of generalizations relating structure to chemical and physical properties, as measured by instrumentation. This ‘Instrumental Revolution’ in organic chemistry was two-fold: encompassing an embrace of new tools that provided unprecedented access to structures, and a new way of thinking about molecules and their reactivity in terms of shape and structure. These practices suggest the possibility of a change in the ontological status of chemical structures, brought about by the regular use of instruments. The career of Robert Burns Woodward (1917–1979) provides the central historical examples for the paper. Woodward was an organic chemist at Harvard from 1937 until the time of his death. In 1965, he won the Nobel Prize in Chemistry.     

Forecasting contemporaneous aggregates and the combination of forecasts: The case of the U.K. monetary aggregates

A number of papers in recent years have investigated the problems of forecasting contemporaneously aggregated time series and of combining alternative forecasts of a time series. This paper considers the integration of both approaches within the example of assessing the forecasting performance of models for two of the U.K. monetary aggregates, £M3 and MO. It is found that forecasts from a time series model for aggregate £M3 are superior to aggregated forecasts from individual models fitted to either the components or counterparts of £M3 and that an even better forecast is obtained by forming a linear combination of the three alternatives. For MO, however, aggregated forecasts from its components prove superior to either the forecast from the aggregate itself or from a linear combination of the two.     

The electrons of the dinosaurs and the center of the Earth: comments on D.D. Turner’s ‘The past vs. the tiny: historical science and the abductive arguments for realism’

Turner [The past vs. the tiny: Historical science and the abductive arguments for realism. Studies in History and Philosophy of Science 35A (2004) 1] claims that the arguments in favor of realism do not support with the same force both classes of realism, since they supply stronger reasons for experimental realism than for historical realism. I would like to make two comments, which should be seen as amplifications inspired by his proposal, rather than as a criticism. First, it is important to highlight that Turner’s distinction between ‘tiny’ and ‘past unobservables’ is neither excluding nor exhaustive. Second, even if we agreed with everything that Turner says regarding the arguments for realism and their relative weight in order to justify the experimental or historical version, there is an aspect that Turner does not consider and that renders historical realism less problematic than experimental realism.     

Estimation and prediction under structural instability: The case of the U.S. pulp and paper market

The objectives of this paper are: first, to show empirically the relevance of using adaptive estimation techniques over more traditional estimation approaches when economic systems are believed to be structurally unstable over time; and secondly, to compare in an empirical framework two adaptive estimation techniques: Kalman filtering and the Carbone–Longini filter. For that purpose, an econometric model for the U.S. pulp and paper market is examined under the assumption of structural instability and, hence, constitutes the basis for comparing forecasting performances and estimation accuracy achieved by each technique. A version of Kalman filtering, modified in line with the basic idea of ‘tracking’ characterizing the Carbone–Longini filter, is also presented and applied. The analysis of the results shows that it may be worth using adapative estimation methods to estimate structurally unstable models, even if there is no prior knowledge about the patterns of variation of the parameters. Also, it shows the Carbone–Longini filter and Kalman filtering as being complementary estimation techniques. An estimation/forecasting methodology involving a sequential application mode of these two techniques is suggested.     

Cholinergic and adrenergic innervation of the penis artery of the bull: transmitter concentrations and synaptic vesicles.

The penile artery of the bull contained significant amounts of acetylcholine, noradrenaline and dopamine, and its axon profiles contained either numerous small granular or agranular vesicles, as well as some large granular vesicles. In the dorsal metatarsal artery, only noradrenaline and dopamine were detectable, and the axon profiles observed contained numerous small granular vesicles. In the penile artery, the axons with small agranular vesicles, probably cholinergic axons, were in close contact with axons containing small granular vesicles. It is suggested that, in the penile artery of the bull, one of the functions of the cholinergic nerves is suppression of excitatory adrenergic neurotransmission.     

DNA synthesis in the pituitary gland of the rat: effect of sulpiride and clomiphene.

Sulpiride administration to rats releases prolactin and increases DNA replication in the anterior pituitary gland. Clomiphene prevents the stimulation of DNA synthesis produced by sulpiride, but does not affect prolactin release from the gland. These findings suggest that the intracellular prolactin content of the anterior pituitary gland plays a role in the regulation of DNA synthesis through a mechanism mediated by oestrogens.     

Biogenesis of mitochondrial porin: the import pathway.

We review here the present knowledge about the pathway of import and assembly of porin into mitochondria and compare it to those of other mitochondrial proteins. Porin, like all outer mitochondrial membrane proteins studied so far is made as a precursor without a cleavable 'signal' sequence; thus targeting information must reside in the mature sequence. At least part of this information appears to be located at the amino-terminal end of the molecule. Transport into mitochondria can occur post-translationally. In a first step, the porin precursor is specifically recognized on the mitochondrial surface by a protease sensitive receptor. In a second step, porin precursor inserts partially into the outer membrane. This step is mediated by a component of the import machinery common to the import pathways of precursor proteins destined for other mitochondrial subcompartments. Finally, porin is assembled to produce the functional oligomeric form of an integral membrane protein which is characterized by its extreme protease resistance.     

Experiential and cosmopolitan knowledge: The transcontinental field practices of the U.S. Bureau of Biological Survey

Before many of the global environmental knowledge producing networks and technologies emerged later in the twentieth century, another spatially extended form of field science was implemented at a continental scale by the U.S. Bureau of Biological Survey, revealing similar tensions and dynamics. Specimens and observations from across continental spaces were integrated through railroad-based transportation and communications networks in order to map distributions of birds and mammals and delineate “life zones” stretching across the continent. At the same time that field zoologists of the Biological Survey produced this cosmopolitan scientific knowledge, they also developed an intimate, experiential knowledge of many of the places where they traveled. By following the travels of Biological Survey field parties, especially the agency's long-time chief field naturalist Vernon Bailey, during the late nineteenth and early twentieth centuries when the railroad was dominant, this paper traces the interconnections between the two ways of knowing in the Biological Survey's practice. However, the integration of these different forms of knowledge was ultimately partial and incomplete, as seen through the Survey's daily practices such as food consumption, the seasonality of survey field practice, and limitations on what types of knowledge were incorporated from lay network collaborators and field assistants.     

Extractive components from the nutmeg ofMyristica simarum A. DC.: The structure of lignan-ketone: Otobanone

Summary Otobanon obtained fromn-hexane extract ofMyristica simarum A. DC. was elucidated as 1-oxo-otobain by the physical spectra and chemical degradation.Acknowledgment. The authors are indebted to Chemical Research Center for financial support under the project No. CRC-6203, which supported by the National Council on Science Development of China.