Nonlinear combination parametric resonance of axially accelerating viscoelastic strings constituted by the standard linear solid model

Nonlinear combination parametric resonance is investigated for an axially accelerating viscoelastic string. The governing equation of in-planar motion of the string is established by introducing a coordinate transform in the Eulerian equation of a string with moving boundaries. The string under investigation is constituted by the standard linear solid model in which the material, not partial, time derivative was used. The governing equation leads to the Mote model for transverse vibration by omitting the lo...     

Elektrophysiologische Analyse der Wirkung von Adrenochrom auf das Kaninchengehirn

Summary The action of Adrenochrom on the brain was investigated electrophysiologically on the conscious rabbit. The moderate activation of the somatic behaviour and of the electrical brain-activity can be attributed to an increased activity of the ascending reticular system with simultaneous depression of the medio-thalamic intralaminary recruiting system, as well as to an increased activity of the hippocampus. Specific afferent (somesthetic) systems are only slightly moderated.     

Zur Immunchemie der Klebsiella-Antigene

Summary The capsular (K) and somatic (O) antigens of 72 Klebsiella-type strains were isolated and investigated with respect to their chemical composition and their serological behaviour. The K antigens were found to be acidic heteropolysaccharides carrying serological K specificity. The O antigens are lipopolysaccharides which are O group-specific.     

Vergleichende Elektronenmikroskopie reiner DNS und der DNS des Bakteriennukleoids

Summary The behaviour of pure isolated DNA towards the conditions of fixation and dehydration—prior to ultrathin sectioning—has been studied and compared with the behaviour of the DNA-plasm of the bacterial nucleus. It is found that those conditions which produce coarse coagulation of the free DNA also produce electron opaque bodies of variable aspect inside the bacterial nucleus. The coagulation figures obtained in both situations are very similar. This is a further direct evidence in favour of the view that the bacterial nucleus is an assembly of fine DNA-containing fibrilla in a highly hydrated plasma.     

ACTH-Stimulierung der Corticosteroidbiosynthese durch Freisetzung «gebundener» 21-Desoxypregnene

Summary Impairment of 21-hydroxylation was observed when 4-C¹⁴-cholesterol was transformed into 4-C¹⁴-corticosteroids in slices of bovine adrenal cortex, whereas corticosteroid synthesis from 4-C¹⁴-progesterone proceeded freely. ACTH stimulated corticosteroid formation from 4-C¹⁴-cholesterol but not from 4-C¹⁴-progesterone. It is therefore suggested that ACTH facilitates the «release» of 21-desoxypregnenes, which are present in a «bound» form after synthesis from cholesterol in intact adrenocortical tissue, and which are unavailable for the following reactions without conditioning by ACTH.     

Mitochondrien und Citrullinsynthese in der Leber

Summary By differential centrifugation of rat-liver homogenates prepared in isotonic solutions of mannitol it is possible to obtain mitochondria in suspensions that are apparently free from other cellular components. Our preparation contains all of the enzymes responsible for the conversion of ornithine to citrulline with glutamic acid and ammonium or glutamine. The synthesis is strongly inhibited by Janus green, which is a specific vital stain for mitochondria.     

The role of heuristic appraisal in conflicting assessments of string theory

Over the last three decades, string theory has emerged as one of the leading hopes for a consistent theory of quantum gravity that unifies particle physics with general relativity. Despite the fact that string theory has been a thriving research program for the better part of three decades, it has been subjected to extensive criticism from a number of prominent physicists. The aim of this paper is to obtain a clearer picture of where the conflict lies in competing assessments of string theory, through a close reading of the argumentative strategies employed by protagonists on both sides. Although it has become commonplace to construe this debate as stemming from different attitudes to the absence of testable predictions, we argue that this presents an overly simplified view of the controversy, which ignores the critical role of heuristic appraisal. While string theorists and their defenders see the theoretical achievements of the string theory program as providing strong indication that it is ‘on the right track’, critics have challenged such claims, by calling into question the status of certain ‘solved problems’ and its purported ‘explanatory coherence’. The debates over string theory are therefore particularly instructive from a philosophical point of view, not only because they offer important insights into the nature of heuristic appraisal and theoretical progress, but also because they raise deep questions about what constitutes a solved problem and an explanation in fundamental physics.     

Constraints and divergent assessments of fertility in non-empirical physics in the history of the string theory controversy

This paper examines historic appraisals of string theory to develop a less abstract understanding of the string theory controversy and assessment in non-empirical physics. This historical approach reveals several points of conflict in the controversy, each centring on a constraint. By proceeding stepwise through these constraints, I reveal the role that constraints played in determining divergent assessments of string theory. Rather than disagreement between two competing methods, a level of agreement is found amongst those critical and supportive of string theory as to the commitment to the relevant constraints, but disagreement as to the sufficiency of consistency, the path to background independence and a non-perturbative formulation, and how to interpret the significance of applications. Furthermore, the string theory community itself is shown to be divided in its commitment to the necessity of uniqueness and the legitimacy of anthropic reasoning. These varied assessments, guided by considerations of constraints, have informed divergent claims as to the past and future fertility of string theory. These are claims as to the value of string theory in guiding research in quantum gravity: claims as to whether string theory has and will be valuable as a means rather than an end.     

String theory and general methodology: A mutual evaluation

String theory has been the dominating research field in theoretical physics during the last decades. Despite the considerable time elapse, no new testable predictions have been derived by string theorists and it is understandable that doubts have been voiced. Some people have argued that it is time to give up since testability is wanting. But the majority has not been convinced and they continue to believe that string theory is the right way to go. This situation is interesting for philosophy of science since it highlights several of our central issues. In this paper we will discuss string theory from a number of different perspectives in general methodology. We will also relate the realism/antirealism debate to the current status of string theory. Our goal is two-fold; both to take a look at string theory from philosophical perspectives and to use string theory as a test case for some philosophical issues.     

Zur Bestimmung der Elastizitätsgrenze von Bindegewebsstrukturen in vitro

Summary Biological connective tissues are not perfectly elastic. They contain viscous, friction, and elastic elements. Consequently, complex mechanical behaviour can be observed. It is not possible to determine an elastic limit, as in inorganic solids. There are difficulties in measuring a natural state which can serve as a reference for mechanical testing procedures. The method described generates a steady state in the test specimen and allows the determination of a relative elastic limit.     

Von der Mathematik der nervösen Ordnungsleistung

Summary An exact analysis of the coordination of movements in arthropods and vertebrates leads to the rejection of older explanations in terms of reflex physiology and to a dynamic conception of the process in the central nervous system, which admits of representation by a physical model (as well as of a mathematical formulation). This conception carries with it the implication that locomotion is caused by automatic elements that work in the rhythm of locomotion and are prior to the motor elements.This view stands in close relation to the physiology of the nervous system and to Gestalt psychology.     

Über die Beziehungen zwischen der Lipidlöslichkeit von Pharmaka und ihrem pharmakokinetischen Verhalten

Summary Some correlations between the physicochemical properties of drugs and their pharmacokinetic behaviour are outlined. Based on the permeability characteristics of simple model membranes (porous membrane, lipid membrane) permeation and distribution of drugs in the animal body can be described and understood on simple physico-chemical terms. Some clinically important aspects — the absorption of drugs from the intestinal tract, the passage through the blood-brain-barrier and the renal excretion as governed by passive tubular reabsorption — are discussed in more detail. Thereby it appears that the solubility of a drug in lipid material, which may be suitably expressed as partition coefficient between an organic solvent and a buffer solution of pH 7.4, is a major factor in determining its pharmacokinetic behaviour.     

螺旋钻采煤机螺旋钻杆失稳条件研究

通过考虑动能和势能对螺旋钻杆屈曲的影响,运用能量法研究了螺旋钻杆最大转速与螺旋屈曲时临界轴向力间的关系,建立了螺旋钻杆和轴向临界力间的数学模型。研究表明：螺旋钻杆的失稳条件符合实际,对螺旋钻采煤机设计具有十分重要的指导意义。     

Klangspektrographische Untersuchung der Lautäusserung beim Krallenfrosch,Xenopus laevis

Summary Three different calls of the clawed toadXenopus laevis are described and their sound spectrograms are presented. The male and female have one characteristic call each, which is heard during clasping after stimulating the mating behaviour with chorionic gonadotropin. A second call of the male is heard without hormone treatment, often after feeding or change of water.     

Änderungen der Entladungsfrequenzen des elektrischen Organs bei verschiedenen Verhaltensweisen eines Nilhechtes (Gnathonemus petersii)

Summary Observing the discharge-frequencies of the electrical organ ofGnathonemus petersii, it was found that there are characteristic frequencies in relation to different behaviour as: slow and fast swimming, at rest, at appetive and agressive behaviour. No such characteristic frequencies could be detected in relation to comfort movements.     

Untersuchungen zum Verhalten der Ameisenmännchen während der imaginalen Lebenszeit

Summary Marking experiments with the tracer isotopes P³² and I¹³¹ and other behaviour experiments on ant males (Camponotus andFormica) showed that the males live during the imaginal life in several phases: I = social phase; II = rest phase; III = sexual phase; IV = death phase.     

Target space ≠ space

This paper investigates the significance of T-duality in string theory: the indistinguishability with respect to all observables, of models attributing radically different radii to space—larger than the observable universe, or far smaller than the Planck length, say. Two interpretational branch points are identified and discussed. First, whether duals are physically equivalent or not: by considering a duality of the familiar simple harmonic oscillator, I argue that they are. Unlike the oscillator, there are no measurements ‘outside’ string theory that could distinguish the duals. Second, whether duals agree or disagree on the radius of ‘target space’, the space in which strings evolve according to string theory. I argue for the latter position, because the alternative leaves it unknown what the radius is. Since duals are physically equivalent yet disagree on the radius of target space, it follows that the radius is indeterminate between them. Using an analysis of Brandenberger and Vafa (1989), I explain why—even so—space is observed to have a determinate, large radius. The conclusion is that observed, ‘phenomenal’ space is not target space, since a space cannot have both a determinate and indeterminate radius: instead phenomenal space must be a higher-level phenomenon, not fundamental.     

Perception of constant hydrostatic pressure. A physiological basis for the vertical stratification of marine habitats

Summary This paper reports an experimental demonstration of the ability of sessile marine animals (Balanus balanus L., Crustacea, Cirripedia) to perceive constant hydrostatic pressure. The results suggest the presence inBalanus of a previously unknown sensory system with a tonic response. Such a system may also be present in freely moving animals, but be masked by their locomotor activity.This research was supported by the Deutsche Forschungsgemeinschaft (Az. So 78/2).     

Neuformulierung der Kristallographie

Summary A consideration of symmetry in any object or process entails essentially a correlation between parts of a unit or between unit and unit. Enquiry must be made as to what is geometrically distinguishable or indistinguishable and an attempt undertaken to discover the pattern underlying apparent disorder.Crystallography has been the science in which the principles of symmetry have been most extensively applied and received their fullest development. Naturally enough, the system evolved for formulating the symmetry inherent in crystals has been adapted to the specific problems the crystallographer sets out to solve.Such researches, however, go far beyond the bounds of ordinary geometric crystallography and are, in particular, an essential requisite for mastering the problems of stereochemistry. It is, therefore, obviously desirable to find a method of formulation which can be applied to any or all the problems in which the question of symmetry arises, such as the systematic ambiguities or the possible deformations of objects or processes endowed with symmetry. To this end the Element of Symmetry, traditional starting point of investigations into symmetry, must be replaced by the covering operations as such.Symmetry formulæ can be deduced, which beyond merely describing the features involved, permit the detailed numerical calculation of their development and variation. In this respect they must prove of value not only to the chemist in his investigation of isomers etc., but can usefully be adopted also by the crystallographer.A short introduction into this new method of formulation is given in the preceding pages.     

Einige Probleme der Verhaltensforschung bei Insekten,insbesondere Orthopteren

Summary The insects, as animals of purely instinctive behaviour, are prefectly suited for studies in the sense of modern ethology. In a series of examples, especially on the singing orthoptera, several new findings are discussed. But many important problems still remain to be worked out; the insects should be very good objects for further successful studies.

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Herrn Prof.K. v. Frisch zum 70. Geburtstag gewidmet.