Showing papers in "Naturwissenschaften in 1983"

A New Solution to the Problem of the Subjective Vertical

Abstract: Based on new evidence and the extensive literature, this report develops an outline of a comprehensive theory of the subjective vertical (SV) in humans. Traditionally the large deviations of the SV from veridicality are attributed to a failure on the part of the gravity systems to correctly perform the necessary coordinate transformation on the visual system. It is experimentally demonstrated, however, that in the control of posture the gravity systems do in fact work close to perfection in positions where the deviations of the SV from the physical vertical are almost largest. Since also the visual system is known to process angular information veridically in the respective range, the intervention of a third agent is suggested, namely a tendency to shift the SV towards the person's own longitudinal axis (“idiotropic vector”). The predictions of the theory are confirmed experimentally, proving that not only the visual but also the haptic zenith is shifted towards the long axis by strongly correlated amounts, when the head is pitched backwards. The theory is also shown to be compatible with, or amenable to typical properties of the SV response characteristic [1], quantitative neurological data on primate gravity receptors [2], a theory of postural control worked out earlier [3], and a particular type of non-linear interaction also found in other orientation systems [4].

Egyptian blue — Cuprorivaite a window to ancient Egyptian technology

Abstract: Egyptian Blue, a multicomponent synthetic blue pigment has been recorded in ancient Egypt since the Fourth Dynasty of the Old Kingdom (2600–2480 B.C.). The pigment consisting of cuprorivaite (CaCuSi4O10) with variable amounts of wollastonite (CaSiO3), Cu-rich glass and cuprite (Cu3O) or tenorite (CuO) was prepared by melting the copper-rich ingredient with lime and desert sand. Low melting temperatures (below 742 °C) were achieved by addition of flux-like plant ashes. The high quality of the pigments collected from monuments of the Fifth Dynasty (2480–2320 B.C.) may indicate that the first manufacture was in early dynastic or perhaps predynastic eras. During the reign of Thutmosis III (18th Dynasty, 1490–1436 B.C.) probably bronze filings were first applied as starting material, thus indicating a technological innovation. This new method was employed till the Roman times.

Neurobiology of learning and memory: The honeybee as a model system

Abstract: Conditioning experiments with bees demonstrate surprising similarities between the well studied laboratory mammals and honeybees. These similarities appear both on the behavioral level and the neural organization of memory. The paper speculates on the basis of these similarities, and the idea of common neural elements is favored.

Chirality determines pheromone activity for flour beetles

Abstract: Olfactory perception and orientation behaviour of female and male flour beetles (Tribolium castaneum, T. confusum) to single stereoisomers of their aggregation pheromone revealed maximal receptor potentials and optimal attraction in response to 4R,8R-(−)-dimethyldecanal, whereas its optical antipode 4S,8S-(+)-dimethyldecanal was found to be inactive in this respect. Female flour beetles of both species were ≈ 103 times less attracted to 4R,8S-(+)- and 4S,8R-(−)-dimethyldecanal than to 4R,8R-(−)-dimethyldecanal, while male flour beetles failed to respond to the R,S-(+)- and S,R-(−)-stereoisomers. Pheromone extracts of prothoracic femora from unmated male flour beetles elicited higher receptor potentials in the antennae of females than in those of males. The results suggest that the aggregation pheromone emitted by maleT. castaneum as well as maleT. confusum has the stereochemical structure of 4R,8R-(−)-dimethyl-decanal, which acts as sex attractant for the females and as aggregant for the males of both species.

Biochemical processes under high hydrostatic pressure

Abstract: High hydrostatic pressure may cause “metabolic dislocation” at the enzyme level or at the level of cellular processes. As shown by model studies, the underlying mechanisms include changes in quaternary structure and backbone conformation, modification of reactive groups, shifts of equilibria of protein-ligand association, among others. The given effects are connected with pressure-induced alterations of intra- and intermolecular interactions governing protein stability and macromolecular assembly. Changes in hydration are essential for both phenomena. Attempts to use available data to arrive at a clear-cut mechanism of barotolerance (or barophily) have failed so far. Due to the characteristics of deep-sea habitats, barophilic organisms are expected to require adaptation to both high pressure and low temperature, the latter being of greater importance.

The Oklo phenomenon

Abstract: Until recently, scientists believed that the chemical elements were synthesized only in stars. The discovery of the Oklo phenomenon in the Republic of Gabon in 1972 has revealed, however, that a nuclear “fire” had existed on the earth and largescale transmutations of the elements were occurring on our planet 1.7·109 years ago. The formation of natural (or Pre-Fermi) reactors is closely related to the appearance of life on our planet earth. The Pre-Fermi reactors were probably never formed until about 2·109 years ago, when oxygen was injected into the earth's atmosphere by a new generation of living organisms carrying out photosynthesis.

Portrait of an Asian stalk-eyed fly

Abstract: Diopsid flies have eyes set on stalks which are in some cases so long that the distance between the eyes exceeds the body length. These conspicuous structures have given rise to much speculation about their adaptive value, but there are very few actual observations by which to judge these hypotheses.Cyrtodiopsis whitei Curran lives in the tropical rainforest of Malaysia. We describe a number of aspects of its morphology and biology, some functional properties of the eye, and the ritualized fights between males, by which harems are acquired. The evolutionary significance of the eyestalks is discussed: they represent structures subjected to a double selection pressure; they are an adaptation by which a sensory system is better matched to the special problems encountered in a densely structured habitat (in that the field of view is extended and the ability to estimate distance and size and to identify objects at a large distance is improved), also they act as key stimulus for species recognition and as releaser for intraspecific behaviour.

Saurer Regen, eine Folge der Störung hydrogeochemischer Kreisläufe

Abstract: The occurrence of acid precipitation in regions of the northern hemisphere results from the anthropogenic disturbance of cycles that couple land, water and atmosphere. The oxidation of C, S and N resulting mostly from fossil fuel burning rivals oxidation processes induced by photosynthesis; the acidity of rain is a consequence of these redox processes in the atmosphere and in the rain. In evaluating the impact of aqueous acidity upon the environment and vice versa, it is essential to distinguish between free H+ acidity and the H+ reservoir (base-neutralizing capacity). The acidification of lakes, streams and soils is influenced by hydrology, biota, geology and weathering rates.

Dissolution of minerals and hydrometallurgical processes

Abstract: Physical, chemical, electrochemical, and electrolytic processes involved in the dissolution of minerals in aqueous solutions are identified and characterized. Their importance to hydrometallurgy is outlined.

Peripheral interaction in the tympanic organ of a moth

Abstract: face activities the total content of blood group antibody-absorbing substances of Eb cells is considerably higher than that of ESb cells. The conspicuous expression of these substances on the outer surface of ESb cells is evident when the ratios of blood group activities on cell surface over blood group activities of entire cells are compared for the two sublines. This figure is close to unity for ESb cells but much lower for Eb cells. Other components of the cell membranes of ESb and Eb LPHs are likely to be involved in the degree of expression on and transport of blood group active substances to the cell surface. Topography and nature of cell surface structures on ESb lymphoma cells differ from those on Eb cells by numerous parameters [I 5]. Tnand T-specific structures are likely to be involved in adhesion of ESb cells to hepatocytes and may thus be of general importance among numerous factors in the complex process of the \" t ake\" of tumor metastases. This is indicated by the strong inhibition of rosette formation by isolated T antigen and some of its cleavage products as well as some related g!ycoproteins, among them asialo-ovine submaxillary mucin which has high Tn activity [18].

Proprioceptive feedback influences the calling song of the field cricket

Abstract: protection by splenocytes, 27% by control thymocytes and 40% by control splenocytes. Differences between sensitized and control lymphocytes were significant (p < 0.06). In spleen of successfully treated rats 50.1 _+ 16.7% T-lymphocytes and 10.7_+ 4.7 Ia-positive cells were found, compared with 38.7_+ 7.6% T-cells and 13.0 47.5 Ia-positive cells in the spleens of untreated controls. It seems that ICC of tumors principally stimulates thymus-derived lymphocytes, although results were not significantly different (p = 0.1, Wilcoxon test). Most of the animals with solid tumors can be cured by ICC. BCG has an additional but no significant effect. On this tumor therapy, BCG alone did not cure any animal. Hints are given that there is a T-cell-dependent immune response against tumor cells after ICC (Winn assay, monitoring of spleen lymphocytes). This stimulation of the immune system by ICC has to be investigated intensively before ICC is applied in humans for therapy of solid tumors and metastases.

New photochemical reactions leading to spatial dissipative structures

Abstract: I 1 4 44 1 8 4 10 15 274 7 2 8 48 2 0 67 116 9 5 153 3 2 5 10 2 1 9 12 4 2 1 41 2 2 73 14 4 2 1 424 272708 13 9 1 8 4 0,4 3 1 97 329 1 20 32 30 47 1554 30 4 8 113 74-144 271 174369 7 3 1 2 22 16-33 41 33-52 79 49-107 45 29-75 1202 610-2358 34 23-45 4 1,2 5 9 74 2 4 99 213 137 284 3 1 6 16 8 3 2 22 6 2 9 50 26-107 25 9 5 4 793 442-1215 19 13-26 6 1,0 6 8 109 80-136 264 203 441 6 4 1 2 16 6 2 6 30 17-39 47 2 6 84 31 19-51 1112 817 2034 22 17-32 4 1,7 7 9 157 92-272 322 255541 6 2 1 4 16 9 2 5 28 16-37 45 2 2 84 27 10-53 830 448935 20 10-35 7 1,3 8 6 151 46-309 435 165-1488 5 4 8 16 5 2 5 40 13-78 81 29-212 34 29-4

Die [2 n ]Cyclophane — ein Kapitel moderner Aromatenchemie

Abstract: Bridged aromatic compounds, the so-called phanes, are in the center of interest of modern aromatic chemistry. The characteristic properties of this class of compounds are particularly well illustrated by the [2n]cyclophanes, hydrocarbons consisting of two benzene rings and at least two ethano bridges. Following some basic considerations on the synthesis of these compounds, their structural parameters are discussed as well as methods allowing the complete bridging of the two aromatic subunits. Most distinct chemical property of the [2n]cyclophanes is their pronounced propensity to participate in addition reactions. The emerging field of metal complexes of the [2n]cyclophanes is discussed for several selected examples, and a chapter on stacked organic molecules, in which up to eight benzene rings are placed on top of each other, concludes this overview.

Microbial phosphorus release during enhanced glycolysis.

Abstract: Fixation rapide du phosphore dans les conditions aerobies et liberation dans les conditions anaerobies (en l'absence de O 2 et de NO 3 − ) pour les microorganismes des sediments

Decreased response to alarm pheromone by insecticide-resistant aphids

Abstract: not wish to speculate further on the possibility that cytoplasmic DNA is a possible carrier of information across the nuclear and cellular membranes and results from gene amplification during cell differentiation, etc. Nevertheless, the reported undermethylation of cytoplasmic DNA is a most remarkable feature in view of recent studies indicating that DNA methylation is a key event in control of gene function [131.

Fluorescence microphotolysis. Diffusion measurements in single cells.

Abstract: Fluorescence microphotolysis is a versatile method for diffusion measurements in single cells and other microscopic systems. A recent development, continuous fluorescence microphotolysis, extends diffusion measurements to ensembles of a few hundred fluorophores. Cell surface membranes are frequently considered as 2-dimensional fluids. Membrane proteins, dispersed in a fluid bimolecular lipid layer, are expected to be highly mobile in the membrane plane. Such expectations are met by artificial bilayers but not always by cell membranes. As first observed for erythrocytes and subsequently for many other cells translational mobility of membrane proteins can be severely restricted. Frequently, integral membrane proteins have mobile and immobile fractions. In order to account for this duality it has been suggested that cell surface membranes are made up of two layers with opposing dynamic properties: a fluid lipidprotein bilayer, the “membrane skin”, and a rather static protein network, the “membrane skeleton”.

Non-aqueous electrolyte solutions

Abstract: Non-aqueous electrolyte solutions are nowadays intensively studied owing to their unique properties for their application in various electrochemical devices and procedures. Important advances have already been made in high-energy primary batteries, wet capacitors, electroplating, phase-transfer catalysis and electro-organic synthesis; advances are expected in further fields such as high-energy secondary batteries, non-emissive displays, solar cells, thin-film procedures and coating. A survey is given both for successful recent applications and expectations.

Initial activity and voluntary behavior in animals

Abstract: Initiation as a basic property of behavioral activity is functionally analyzed and discussed at the level of voluntary behavior. Fixed action patterns often are not released by stimuli but are generated by the animal itself through brain processes of the Darwinian type. Analogous to mutations, behavioral "subroutines" are brought up by chance and are subjected to selection either by the change in the situation (trial and the elimination of error) or by mental activity suppressing inappropriate behavior even before it is executed. Initiation improves the chance of survival. It is a prerequisite of goal-oriented behavior, an essential constituent of operant conditioning and presumably the first step in the evolution of thought. According to I. Kant a person is free if, by following his own directive, he does what has to be done. This definition meets the two central criteria of initiation: the independence of releasing stimuli and the adaptive value of the behavior generated.

Sexual differentiation of the green alga Volvox carteri. Involvement of extracellular phosphorylated proteins

Abstract: size and surface charge of biocolloids and microemulsions using quasi-elastic light-scattering spectroscopy, in which the measured mutual diffusion coefficient is related to the osmotic pressure gradient through the Stokes-Einstein equation. The osmotic pressure gradients in this case are usually estimated from the second virial coefficient [13]. Although this is a better approximation than the assumption of hardsphere behavior, the second virial coefficient underestimates the pressure gradient severely except at extreme dilution.

Efferent neurosecretory fibres as pathways for circadian clock signals in the scorpion

Abstract: a p<0.005; b p<0.001; NS not significant diately separated, weighed and fixed in Bouin's fluid. Paraffin sections of 5 gm of the testes were made and stained with hematoxylin and eosine. A decrease in body weight was found in both chicory-fed groups (B&C). Also a decrease in testicular weight was observed in Gr. C (Table 1). Definite changes in the form of degeneration in the seminiferous tubules and atrophied Leydig cells in testes were present in mice fed with 8.7 g chicory/kg (Gr. C). Furthermore, the seminiferous tubular lumen was filled up with desquamated cells and debris (Fig. 1). Spermatogenic ceils and Leydig cells were not affected notably in Gr. B, which received 4.3 g chicory/kg. The antifertility effect and anti-implantation efficacy in the extract of different parts of the plant were suggested [6]. This study reveals definite impairment of spermatogenesis in mice fed with 8.7 g chicory/kg.

Mixed-valent Iron in Synthetic Rasvumite, KFe2S3

Abstract: cases apparently typical structures developed at the interface, d) To test the possibility of mass-transfer within the solution, a 0.5 mW helium-neon laser illuminated a small area just below the surface, and the solution mixed with different types of dusts, e.g. aluminum dust and fumed silica (Aerosil). Similarly, hydrophobic reverse-phased fumed silica (Aerosil R972) was sprinkled on the surface. Laser illumination very clearly showed individual red speckles of the dust particles [14], however no bulk or surface movements were apparent during UV illumination. e) Kafri recently developed a sensitive deflectometry-type method [15] which utilizes laser light and Ronchi rulings. Hydrodynamic movements are easily detected by this technique, yet again no such movements were seen in our case. It seems to us that the phenomenon is purely due to diffusion processes or, at the most, to microscopic movements which we have not yet been able to detect. In our forthcoming paper we have expanded the phenomenon to purely thermal systems, suggesting that symmetry breaking is due to the buildup of concentration instabilities at the interface, as postulated theoretically by several authors [16].

Drei neue Nickelenzyme aus anaeroben Bakterien

Abstract: Until recently nickel was not considered to be an element of biological importance Nutritional studies have shown, however, that many eucaryotic and procaryotic organisms are dependent on the transition metal for growth Four enzymes are presently known to contain nickel: urease from plants and from bacteria; methyl CoM reductase from methanogenic bacteria; all “uptake” hydrogenases investigated so far; and carbon monoxide dehydrogenase from anaerobic bacteria The prosthetic group of the methyl CoM reductase has been identified as a nickel tetrapyrrole, the structure of which has been elucidated