Variabilität des Paarungsrufes der Geburtshelferkröte,Alytes o. obstetricans

Summary Studying the acoustic behaviour of the midwife toad, the mating call was found to be influenced by the air temperature and the size of the animals. When the air temperature rises the number of calls/min and the basic frequency exhibit a positive linear regression, the duration of the calls a negative linear regression. As the animals grow the frequency decreases while the duration increases.     

The composition of Taft E s o constants: An application of biased alternatives to least squares

Summary A systematic analysis of the composition of E _s ^o like rate constants clearly revealed that Taft E _s ^o -values depend upon the size of the substituents. Further evidence in favor of this view is adduced even in a case where OLS led to the conclusion that E _s ^o should be completely independent of the size of the substituents, since biased estimators (PCRA, LRRA) showed that this statement is not correct. Furthermore, it seems that the magnitude of the steric effect represented by E _s ^o is a function of the thickness of the substituent along 2 directions perpendicular on its main axis and is not influenced by its length.Acknowledgment. We would like to thank Prof. J.T. Webster, Department of Statistics, Southern Methodist University, Dallas, for sending us s computer program of latent root regression analysis. We also thank the referees whose insightful comments were most helpful in improving the presentation.     

用非线性反馈控制混沌R(o)ssler系统到达任意目标

本文设计了识别不确定R(o)ssler系统未知参数的观测器,提出了控制R(o)ssler系统中混沌的非线性反馈控制策略.数值模拟结果表明:观测器可以有效地标识未知参数;选取不同的目标参数,既可以使R(o)ssler系统稳定在不同周期轨道上,也可以稳定在任意目标点上.     

Presenza di enteramina o di una sostanza enteraminosimile negli estratti gastrointestinali e splenici dei pesci e negli estratti gastroenterici delle Ascidie

Summary It was possible to demonstrate, by means of chemical and biological reactions, the presence of enteramine or of an enteramine-like substance in gastro-intestinal extracts of twoAscidi, Tethium plicatum andCiona intestinalis.The same substance was also found in gastric and still more in intestinal extracts ofSelacia, but seems not to be present in the spleen ofSelacia nor in the alimentary canal ofTeleostea.     

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.     

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.     

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).