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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Acta biotheoretica 1 (1935), S. 100-112 
    ISSN: 1572-8358
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Description / Table of Contents: Résumé La vie est un phénomène complexe, se composant de différents phénomènes causals, qui un jour peut-être seront réduits à la causalité physique et chimique. Cependant connaitre toutes les causes des phénomènes vitaux ne signifie pas connaître la vie. Le problème de la vie ne se borne pas aux rapports causals, mais implique surtout les rapports intercausals, c'est à dire l'harmonie ou l'équilibre de ses parties constituantes. La vie comme phénomène est provoquée par une „structure causale”. Tandis que les causes sont trouvées par l'analyse, les rapports intercausals doivent être recherchés par la synthèse, c'est-à-dire par la réconstruction de la réalité de l'organisme vivant en se servant des données analytiques. Le système vivant est en équilibre énergétique et spécifique. Les facteurs énergétiques sont interlacés de telle façon, qu'ils s'activent entre eux et qu'ils se forcent entre eux à se resteindre au développement de l'énergie nécessaire. Un équilibre physique c'est l'état d'énergie libre minimum, tandis que l'équilibre biologique c'est un état d'énergie organisée. Dans un équilibre spécifique on ne peut se borner aux effects causals se manifestant par un phénomène. Il faut décrire les rapports des propriétés spécifiques de tous les facteurs; ce sont ces propriétés qui leur permettent d'agir comme cause, lorsqu'-ils sont atteint d'une excitation spécifique. Les facteurs possèdent au moins deux propriétés spécifiques, adaptées à deux facteurs voisins, comme chaque anneau d'une chaine s'adaptant à deux anneaux voisins („caractère d'ambocepteur”; exemple: la sécretine s'adaptant d'un côté à l'acide contenu dans le duodenum et de l'autre côté au bicarbonat de soude du pancréas). Le fait que l'on trouve dans chaque individu ces deux formes d'équilibre (équilibre d'énergie et équilibre spécifique) nous donne le droit de créer le concept du „tout” par rapport auquel on peut constater l'harmonie de tous les tacteurs. C'est là le „tout statique”, reste encore le „tout dynamique” qui se manifeste par la croissance et probablement par les phénomènes se produisant dans l'écorce cérébrale, base des actes psychiques. Les parties (en ce cas spécial les cellules) représentent beaucoup de possibilités qui ne se réalisent pas; p.e. les blastomères peuvent représenter le „tout” de l'organisme, tandis qu'ils se borneront dans la croissance normale à la production d'une part de l'individu. Il y a une interaction entre tous les blastomères, de façon que, par la suppression ou par l'activation mutuelle, chaque partie réalise ce que lui laissent les autres et ce qui est en harmonie avec ce que produiront les autres. De cette façon il y aura de l'harmonie dans tout ce qui sera produit. Les parties agissent par cette interaction, non selon leur „être”, en tant que cellule isolée, mais selon leur „rôle” dans le „tout” du germe, rôle qui est déterminé par cette interaction mutuelle universelle. C'est cette interaction qui détermine le „patron causal”, responsable de chaque étappe de la coissance. Ainsi ce ne sont pas les facteus isolés, mais le réseau des rapports établis entre tous les facteurs, qui gouvernent les phénomènes de la croissance. Ce réseau, par activation ou par suppression, détermine à chaque instant les propriétés causales des parties, d'entre toutes les multiples possibilités. Les possibilités étant données dans les cellules, c'est le „tout” du réseau des rapports qui détermine la croissance. Le matérialisme n'a vu que les causes isolées, telles qu'ellés se manifestent dans les expériences des physiciens, grâce à la technique; le vitalisme n'a vu que le „tout”, sans tâcher de l'analyser afin de trouver à sa base le système causal compliqué, que nous avons tâché de décrire. Dans la réalité la théorie du causalisme (matérialisme) ni celle du vitalisme le tiennent plus de bout.
    Notes: Summary Life as a complicated process is composed of causal phenomena. But even if we know the reasons of all that happens in a living organism, we do not know what life really is. The problem of intercausal relation, of “causal structure” remains. The reason why a process takes place, must be found by analysis, causal structures are found by synthesis of the results of this analysis. Causal structures are characterized by two kinds of equilibrium: energetic and specific equilibrium. A state of physical equilibrium is characterized by a minimum of free energy; a biological energetic equilibrium is an organized one, where the vital factors activate the production of energy by each other and force each other to limit that production to the necessary measure. A specific equilibrium is characterized by the properties of its factors, properties by which those factors act as a cause after having received a specific stimulation. Every factor possesses two (or more) specific properties, in accordance with the properties of two neighbouring factors, as a link between two other links in a chain (“amboceptor-character”: e.g. secretine between hydrochloric acid from stomach and sodium bicarbonate from the pancreas). Both forms of equilibrium authorise us to speak of living systems as a “whole”. In the second part of this paper we treat the dynamic aspect of the functions of living systems as a “whole”. This dynamic aspect manifests itself in growth and probably in cortical functions. Blastomeres represent, when isolated, the “whole” of growing potentialities of a germe. In normal contact with each other they restrict themselves to produce a part of that “whole”, in harmony with that which other blastomeres produce. This harmonious restriction can be explained by interaction between all the blastomeres by which every blastomere suppresses in other blastomeres all that it will produce itself. Blastomeres must therefore act on other blastomees not according to their isolate “being”, but according to the influences which they undergo by all other blastomeres, that means according to their “rôle”. There must be a causal net of interaction between all the blastomeres and that net “as a whole” determines every step of growth. Such a net of relation determines also human history and sociology. Materialism only took account of isolated causes, vitalism only of the effect of the net of causal relations without understanding that such a net might be analysed. In reality there is neither materialism nor vitalism.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-0533
    Keywords: Innervation ; Axonal regeneration ; Nerve terminal ; Motor endplate ; Collateral sprouting
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract In the present study we examined the effect of recombinant human ciliary neurotrophic factor (rH-CNTF) on muscle fibre reinnervation. After facial nerve crush, rats were treated systemically with either rH-CNTF (1 mg/kg per 48h) or saline and were killed on days 10–13 after nerve crush when muscle fibre reinnervation becomes apparent. Blind counting of the numbers of reinnervated motor endplates and the length of the synaptophysin-positive staining was used to assess the effect of CNTF treatment on muscle fibre reinnervation in the whisker muscle. On day 10, both treatment groups showed a limited number of reinnervated motor endplates. Both the saline-and CNTF-treated rats showed a significant increase in the percentage of reinnervated motor endplates and in the length of the synaptophysin-positive staining with time. On days 10 and 11, there was no difference in muscle fibre reinnervation between the treated groups. On days 12 and 13, the CNTF-treated rats showed an increased muscle fibre reinnervation which was significant compared to the saline-treated rats. These results suggest that after facial nerve crush in young rats, CNTF enhances muscle fibre reinnervation, most probably by stimulating the intramuscular branching. There is no support for an effect of CNTF on nerve sprouting in the proximal axonal part or on axonal elongation; the CNTF effect on intramuscular branching might be mediated by the muscle fibres.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    International archives of occupational and environmental health 64 (1992), S. 281-291 
    ISSN: 1432-1246
    Keywords: Shipyard ; Welding ; Turnover ; Selected employment ; Work disability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary A 40-year historical cohort study of medical wastage among about 550 shipyard welders and 1100 controls (shipwrights and engine fitters), all employed at the same shipyard, was carried out. The welders left their job 20% more often than the controls; the excess considerably increased with duration of employment. Wastage was particularly due to respiratory, cardiovascular, locomotor and mental disorders. Both welders and controls contributed considerably (about 20%) to permanent work disability. Medical wastage among welders because of respiratory diseases was more than four times higher than among controls, which could not be explained by differential smoking habits alone. The study raises concern about locomotor health hazards for shipyard workers. Moreover, it underscores the need to reduce the large excess risk of respiratory diseases among shipyard welders. The same may be true for welders in other large metal construction plants, e.g. in boiler production.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1432-203X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary Cell suspension cultures, derived from roots of Podophyllum hexandrum Royle (Berberidaceae), accumulate podophyllotoxin. In this study the use of β-cyclodextrin in feeding the poorly water-soluble precursor coniferyl alcohol to these cultures is described. By complexation with β-cyclodextrin, a solution of 3 mM coniferyl alcohol could be fed, resulting in enhanced podophyllotoxin accumulation. The same concentration of non-complexed suspended coniferyl alcohol had only little effect on the podophyllotoxin accumulation. β-Cyclodextrin itself was proven to be non-toxic for the cells. It did not influence the podophyllotoxin content and it was not metabolized or used as a carbon source by the cells. For comparison, coniferin, the water-soluble β-D-glucoside of coniferyl alcohol, was also fed in the same concentration. The effect of coniferin on the podophyllotoxin accumulation was stronger than that of coniferyl alcohol complexed with β-cyclodextrin, but coniferin is not commercially available.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 22 (1994), S. 423-436 
    ISSN: 1432-1017
    Keywords: Computer simulation ; DPPC ; Bilayer ; Liquid crystalline
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract We present the results of molecular dynamics (MD) simulations of a phospholipid membrane in water, including full atomic detail. The goal of the simulations was twofold: first we wanted to set up a simulation system which is able to reproduce experimental results and can serve as a model membrane in future simulations. This goal being reached it is then further possible to gain insight in to those properties that are experimentally more difficult to access. The system studied is dipalmitoylphosphatidylcholine/water, consisting of 5408 atoms. Using original force field parameters the membrane turned out to approach a gel-like state. With slight changes of the parameters, the system adopted a liquid-crystalline state. Separate 80 ps runs were performed on both the gel and liquid-crystalline systems. Comparison of MD results with reliable experimental data (bilayer repeat distance, surface area per lipid, tail order parameters, atom distributions) showed that our simulations, especially the one in the liquid-crystalline phase, can serve as a realistic model for a phospholipid membrane. Further analysis of the trajectories revealed valuable information on various properties. In the liquid-crystalline phase, the interface turns out to be quite diffuse, with water molecules penetrating into the bilayer to the position of the carbonyl groups. The 10–90% width of the interface turns out to be 1.3 nm and the width of the hydrocarbon interior 3.0 nm. The headgroup dipoles are oriented at a small angle with respect to the bilayer plane. The resulting charge distribution is almost completely cancelled by the water molecules. The electron density distribution shows a large dip in the middle of the membrane. In this part the tails are more flexible. The mean life time between dihedral transitions is 20 ps. The average number of gauche angles per tail is 3.5. The occurrence of kinks is not a significant feature.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1432-1009
    Keywords: Environmental impact ; Assessment process ; Watershed modification ; Impoundment ; River diversion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Energy, Environment Protection, Nuclear Power Engineering
    Notes: Abstract This article reviews the application of environmental impact assessment (EIA) procedures and practices to three watershed modification projects situaled in western Canada. These ventures were justified for accelerating regional economic development, and cover the period during which public concerns for protecting the environment rapidly made their way into the national political agenda. An historical account and analysis of the situation, therefore, seems desirable in order to understand the development of EIA processes, practices, and methodologies since the start of construction of the first project in 1961. This study concludes that there has been good progress in predicting and evaluating environmental and related social impacts of watershed modification proposals. However, a number of obstacles need to be overcome before EIA can firmly establish itself as an effective planning tool. These difficulties include jurisdictional confusions and conflicts, division of authority and responsibility in designing and implementing appropriate mitigative and monitoring measures, lack of tested EIA methodologies, and limited availability of qualified human resources. A number of conclusions and suggestions are offered so that future watershed modification proposals may be planned and implemented in a more environmentally sustainable fashion. These include: (1) EIA processes must be completed before irrevocable decisions are made. (2) Any major intrusion into a watershed is likely to impact on some major components of the ecosystem(s). (3) Mitigation costs must form part of the benefit-cost analysis of any project proposal. (4) Interjurisdictional cooperation is imperative where watersheds cross political boundaries. (5) The EIA process is a public process, hence public concerns must be dealt with fairly. (6) The role of science in the EIA process must be at arms length from project proponents and regulators, and allowed to function in the interest of the protection of the environment and public health and safety.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    Digestive diseases and sciences 35 (1990), S. 1146-1152 
    ISSN: 1573-2568
    Keywords: myenteric plexus ablation ; smooth muscle ; enteric innervation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Alterations in smooth muscle responsiveness and neural pathways in adjacent tissue may occur after local myenteric denervation. The in vitro contractile responses of both longitudinal and circular muscle to the mixed muscarinic and nicotinic cholinergic agonist carbachol were determined 15, 30, and 45 days after localized myenteric plexus ablation. Denervated longitudinal muscle exhibited decreased responsiveness to carbachol at all times examined. Denervated circulated muscle was initially supersensitive, but with time became subsensitive. These changes probably reflect the loss of the nicotinic (neuronal) component of the action of carbachol. Muscle orad to the site of denervation appeared subsensitive, while muscle caudad to the lesion was supersensitive (circular) or unaffected (longitudinal). These results suggest that there are changes in ascending and descending neural pathways. Alterations in the cholinergic responsiveness of intestinal smooth muscle, both at and beyond the site of myenteric plexus ablation, may result in altered intestinal motility that could lead to functional obstruction.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Molecular biology reports 18 (1993), S. 1-13 
    ISSN: 1573-4978
    Keywords: endonuclease ; intron ; maturase ; mitochondria ; RNA splicing ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 9
    Electronic Resource
    Electronic Resource
    Springer
    Molecular biology reports 19 (1994), S. 183-194 
    ISSN: 1573-4978
    Keywords: mitochondria ; protein synthesis ; yeast
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Journal of computer aided molecular design 6 (1992), S. 97-112 
    ISSN: 1573-4951
    Keywords: Cyclosporin A ; Conformational search ; MD ; NOE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary A major problem in modelling (biological) macromolecules is the search for low-energy conformations. The complexity of a conformational search problem increases exponentially with the number of degrees of freedom which means that a systematic search can only be performed for very small structures. Here we introduce a new method (PEACS) which has a far better performance than conventional search methods. To show the advantages of PEACS we applied it to the refinement of Cyclosporin A and compared the results with normal molecular dynamics (MD) refinement. The structures obtained with PEACS were lower in energy and agreed with the NMR parameters much better than those obtained with MD. From the results it is further clear that PEACS samples a much larger part of the available conformational space than MD does.
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