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  • Articles  (259,555)
  • 1970 - 1974  (259,555)
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  • 1
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    Springer
    Mathematical programming 6 (1974), S. 281-300 
    ISSN: 1436-4646
    Source: Springer Online Journal Archives 1860-2000
    Topics: Computer Science , Mathematics
    Notes: Abstract A triangulation of the nonnegative orthant and a special labeling of the vertices lead to a combinatorial procedure for seeking solutions or approximate solutions to the nonlinear complementarity problem under coercive-like assumptions on the problem functions. Derivatives are not required. Convergence is proved, computational considerations are discussed, and some preliminary applications to convex programming and saddle point computation, along with numerical results, are presented.
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  • 2
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    Mathematical programming 6 (1974), S. 117-117 
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  • 3
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    Mathematical programming 6 (1974), S. 121-140 
    ISSN: 1436-4646
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    Topics: Computer Science , Mathematics
    Notes: Abstract This nested decomposition algorithm is intended for solving linear programs with the staircase structure that is characteristic of dynamic multi-sector models for economic development. Staircase problems represent a special case of the discrete-time optimal control problem. Our method is based upon the same principles as that of Glassey [5], but appears easier to describe and to relate to control theory. Computational experience is reported for a series of test problems. The algorithm has been coded in MPL, an experimental language for mathematical programming. This translator has made it possible to obtain a more readable program — and with fewer instructions — than one written in a conventional language. However, because the present version of MPL does not permit the use of slow access memory, this has prevented us from exploring the full potential of nested decomposition for solving larger problems than can be handled by conventional simplex techniques.
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  • 4
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    Notes: Abstract Given a mappingF from real Euclideann-space into itself, we investigate the connection between various known classes of functions and the nonlinear complementarity problem: Find anx * such thatFx * ⩾ 0 andx * ⩾ 0 are orthogonal. In particular, we study the extent to which the existence of au ⩾ 0 withFu ⩾ 0 (feasible point) implies the existence of a solution to the nonlinear complementarity problem, and extend, to nonlinear mappings, known results in the linear complementarity problem on P-matrices, diagonally dominant matrices with non-negative diagonal elements, matrices with off-diagonal non-positive entries, and positive semidefinite matrices.
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  • 5
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    Mathematical programming 6 (1974), S. 62-88 
    ISSN: 1436-4646
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    Notes: Abstract The “relaxation” procedure introduced by Held and Karp for approximately solving a large linear programming problem related to the traveling-salesman problem is refined and studied experimentally on several classes of specially structured large-scale linear programming problems, and results on the use of the procedure for obtaining exact solutions are given. It is concluded that the method shows promise for large-scale linear programming
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  • 6
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    Mathematical programming 6 (1974), S. 105-109 
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  • 7
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    Mathematical programming 6 (1974), S. 89-104 
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    Notes: Abstract The general Fermat problem is to find the minimum of the weighted sum of distances fromm destination points in Euclideann-space. Kuhn recently proved that a classical iterative algorithm converges to the unique minimizing point , for any choice of the initial point except for a denumerable set. In this note, it is shown that although convergence is global, the rapidity of convergence depends strongly upon whether or not  is a destination. If  is not a destination, then locally convergence is always linear with upper and lower asymptotic convergence boundsλ andλ′ (λ ≥ 1/2, whenn=2). If  is a destination, then convergence can be either linear, quadratic or sublinear. Three numerical examples which illustrate the different possibilities are given and comparisons are made with the use of Steffensen's scheme to accelerate convergence.
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  • 8
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    Mathematical programming 6 (1974), S. 234-240 
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  • 9
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    Mathematical programming 6 (1974), S. 114-116 
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  • 10
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    Mathematical programming 6 (1974), S. 110-113 
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    Topics: Computer Science , Mathematics
    Notes: Abstract For a collection of subsets of a setS, letn k be the maximal number of sets from such that no point ofS belongs to more thank of them. Then the limitδ of the sequencen k /k is related to the valuev of the game in which the minimizer selects a setα in , the maximizer a pointx inS, and the payoff isϰ α (x), byδ≤v −1≤inf v δ v . Herev is any finite subset ofS and δ v the corresponding limit. Analogous results hold for covering. The bounds obtained in this way forn k and in particularn 1 reflect the influence of the boundary ofS when, for instance,S is a convex body to be packed with congruent copies of another body. In some cases, the bounds are sharp.
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  • 11
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    Mathematical programming 6 (1974), S. 118-118 
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  • 12
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    Mathematical programming 6 (1974), S. 119-119 
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  • 13
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    Notes: Abstract Implicit function formulas for differentiating the solutions of mathematical programming problems satisfying the conditions of the Kuhn—Tucker theorem are motivated and rigorously demonstrated. The special case of a convex objective function with linear constraints is also treated with emphasis on computational details. An example, an application to chemical equililibrium problems, is given. Implicit function formulas for differentiating the unique solution of a system of simultaneous inequalities are also derived.
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  • 14
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    Mathematical programming 6 (1974), S. 157-166 
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    Notes: Abstract The purpose of this paper is to study a generalization of the concept of blocking and antiblocking polyhedra that has been introduced by D.R. Fulkerson. The polyhedra studied by Fulkerson are restricted to the nonnegative orthant in R m . The present generalization considers sets restricted to a cone. This leads to two polarity correspondences, which are related to the Minkowski polarity for convex sets.
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  • 15
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    Notes: Abstract In earlier results by Sposito and David, Kuhn—Tucker duality was established over nondegenerate cone domains (not necessarily polyhedral) without differentiability under a certain natural modification of the Slater condition, in addition to the convexity of a certain auxiliary set. This note extends Kuhn—Tucker duality to optimization problems with both nondegenerate and degenerate cone domains. Moreover, under a different condition than presented in earlier results by the author, this note develops Kuhn—Tucker duality for a certain class of nonlinear problems with linear constraints and an arbitrary objective function.
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  • 16
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    Mathematical programming 6 (1974), S. 180-196 
    ISSN: 1436-4646
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    Topics: Computer Science , Mathematics
    Notes: Abstract A zero–one matrix is called perfect if the polytope of the associated set packing problem has integral vertices only. By this definition, all totally unimodular zero–one matrices are perfect. In this paper we give a characterization of perfect zero–one matrices in terms offorbidden submatrices. Perfect zero–one matrices are closely related to perfect graphs and constitute a generalization of balanced matrices as introduced by C. Berge. Furthermore, the results obtained here bear on an unsolved problem in graph theory, the strong perfect graph conjecture, also due to C. Berge.
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  • 17
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    Notes: Abstract This paper presents an extension of Tomlin's penalties for the branch-and-bound linear mixed integer programming algorithm of Beale and Small. Penalties which are uniformly stronger are obtained by jointly conditioning on a basic variable and the non-basic variable yielding the Tomlin penalty. It is shown that this penalty can be computed with a little additional arithmetic and some extra bookkeeping. The improvement is easy to incorporate for the normal case as well as when the variables are grouped into ordered sets with generalized upper bounds. Computational experience bears out the usefulness of the extra effort for predominantly integer problems.
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  • 18
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    Mathematical programming 6 (1974), S. 197-211 
    ISSN: 1436-4646
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    Topics: Computer Science , Mathematics
    Notes: Abstract Given an existing network, a list of arcs which could be added to the network, the arc costs and capacities, and an available budget, the problem considered in this paper is one of choosing which arcs to add to the network in order to maximize the maximum flow from a sources to a sinkt, subject to the budgetary constraint. This problem appears in a large number of practical situations which arise in connection with the expansion of electricity or gas supply, telephone, road or rail networks. The paper describes an efficient tree-search algorithm using bounds calculated by a dynamic programming procedure which are very effective in limiting the solution space explicitly searched. Computational results for a number of medium sized problems are described and computing times are seen to be very reasonable.
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  • 19
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    Mathematical programming 6 (1974), S. 229-233 
    ISSN: 1436-4646
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    Topics: Computer Science , Mathematics
    Notes: Abstract A particular case of a mathematical theorem of F. Browder on the behavior of the fixed point set of a mapping under variations of a parameter has recently found applications in programming theory in connection with the abstract (non-linear) complementarity problem (see Eaves, [2, 3]). Two relevant extensions of Browder's result are provided: The first asserts that, under smoothness assumptions, the connected set of fixed points one gets from Browder's theorem is “generically” an arc; the second gives a generalization to the case where the mapping is an upper hemicontinuous contractible valued correspondence.
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  • 20
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  • 21
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    Mathematical programming 6 (1974), S. 240-240 
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  • 22
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    Mathematical programming 6 (1974), S. 241-241 
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  • 23
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    Mathematical programming 6 (1974), S. 242-242 
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    Mathematical programming 6 (1974), S. 243-263 
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    Notes: Abstract Complementary pivot algorithms known at the present time fall into several quite general categories, with obvious similarities. This paper deals with general pivoting systems which provide a natural setting for the study of complementary pivot algorithms. A generalized algorithm is presented for these systems. We give results on the number of iterations necessary for such an algorithm.
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  • 25
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    Mathematical programming 7 (1974), S. 253-258 
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  • 26
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    Mathematical programming 7 (1974), S. 259-259 
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  • 27
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    Notes: Abstract This paper describes two numerically stable methods for unconstrained optimization and their generalization when linear inequality constraints are added. The difference between the two methods is simply that one requires the Hessian matrix explicitly and the other does not. The methods are intimately based on the recurrence of matrix factorizations and are linked to earlier work on quasi-Newton methods and quadratic programming.
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  • 28
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    Mathematical programming 7 (1974), S. 376-379 
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    Mathematical programming 7 (1974), S. 97-107 
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    Notes: Abstract The concept of an optimal flow in a multiple source, multiple sink network is defined. It generalizes maximal flow in a single source, single sink network. An existence proof and an algorithm are given.
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  • 30
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    Mathematical programming 7 (1974), S. 249-252 
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  • 31
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    Mathematical programming 7 (1974), S. 110-112 
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  • 32
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    Mathematical programming 7 (1974), S. 117-143 
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    Notes: Abstract The paper surveys the basic results and nonresults for decision rules in stochastic programming. It exhibits some of the difficulties encountered when trying to restrict the class of acceptable rules to those possessing specific functional forms. A liberal dosage of examples is provided which illustrate various cases. The treatment is unified by making use of the equivalence of various formulations which have appeared in the literature. An appendix is devoted to the P-model for stochastic programs with chance constraints.
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  • 33
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    Notes: Abstract An algorithm for solving ordinary geometric programs is presented. The algorithm is based on the reduced system associated with geometric programs and is highly flexible in that it allows the use of several nonlinear optimization techniques.
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  • 34
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    Mathematical programming 7 (1974), S. 212-222 
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    Notes: Abstract In the last 15 years, a good deal of effort has been devoted to the study of the shortest route problem. More than 200 publications are known but little has been reported concerning relative efficiencies. For a long time the Dijkstra method was considered the most efficient one. Programming work, using different data structures and implementation techniques for several algorithms, has shown that a variant of Moore's method seems to be most efficient for different types of graph structures. The main objective of this paper is to show the strong relationship between an algorithm and its implementation.
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  • 35
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    Mathematical programming 7 (1974), S. 240-244 
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  • 36
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    Notes: Abstract A class of polytopes is defined which includes the polytopes related to the assignment problem, the edge-matching problem on complete graphs, the multi-dimensional assignment problem, and many other set partitioning problems. Modifying some results due to Balas and Padberg, we give a constructive proof that the diameter of these polytopes is less than or equal to two. This result generalizes a result obtained by Balinski and Rusakoff in connection with the assignment problem. Furthermore, it is shown that the polytope associated with the travelling salesman problem has a diameter less than or equal to two. A weaker form of the Hirsch conjecture is also shown to be true for this polytope.
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  • 37
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    Mathematical programming 7 (1974), S. 262-262 
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  • 38
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    Meteorology and atmospheric physics 23 (1974), S. 217-226 
    ISSN: 1436-5065
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    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Es wird ein Zweischichtenmodell der planetaren Grenzschicht vorgeschlagen. In der bodennächsten Schicht wird der theoretisch und experimentell gut untersuchte turbulente Austauschkoeffizient verwendet. Oberhalb der bodennächsten Schicht werden die Bewegungsgleichungen näherungsweise mit einem turbulenten Austauschkoeffizienten gelöst, der einer willkürlich angenommenen, mit der Höhe jedoch nicht sehr rasch sich ändernden Funktion entspricht. Mit dem Widerstandsgesetz wird die Höhe der bodennächsten Schicht bestimmt.
    Notes: Summary A two-layer model of the planetary boundary layer is suggested. In the surface layer the theoretically and experimentally well studied coefficient of turbulent exchange is used. Above the surface sublayer the equations of motion are approximately solved with a coefficient of turbulent exchange in an arbitrary but not quickly varying height function. By means of the resistance law the height of the surface sublayer is found.
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  • 39
    ISSN: 1436-5065
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    Topics: Geography , Physics
    Description / Table of Contents: Summary For the so-called “Hamburg flood catastrophy cyclone” changes of the available potential and the kinetic energy due to the horizontal and vertical fluxes inside the total area from 60°W to 30°E and 40°N to 75°N have been investigated. In the mean over the investigation time the horizontal transport leads to an increase of the total available potential energy in the lower and upper troposphere and a decrease in the middle troposphere. The vertical transport however causes an opposite energy change. After a separation of the total energy into a zonal and a large scale turbulent part it was shown, that for the budget of the zonally available potential energy the horizontal transport causes an accumulation of enery inside the troposphere and an energy loss inside the lower stratosphere. An opposite result was obtained for the eddy available potential energy. For the budget of the total kinetic energy and by averaging over the vertical and over time potential energy was shown to be transported into the region of investigation and kinetic energy was transported out. Thereby a total increase of energy occured inside the region, which can be used for conversion into available potential energy. The dominant amounts are the large scale turbulent parts.
    Notes: Zusammenfassung Für die sogenannte „Hamburger Sturmflutzyklone” wird die im Gebiet von 60°W bis 30°E und von 40°N bis 75°N durch horizontale und vertikale Flüsse hervorgerufene Veränderung der verfügbaren potentiellen und der kinetischen Energie untersucht. Im zeitlichen Mittel wird durch Horizontaltransport in der unteren und oberen Troposphäre die totale verfügbare potentielle Energie vermehrt, während in der mittleren Troposphäre eine Verminderung erfolgt; gegenläufig dazu erfolgt die durch Vertikaltransport hervorgerufene Änderung. Eine Aufspaltung in den zonalen und in den großturbulenten Anteil ergibt, daß im Haushalt der zonalen verfügbaren potentiellen Energie der Horizontaltransport eine Akkumulierung von Energie in der Troposphäre und einen Energieverlust in der unteren Stratosphäre hervorruft. Umgekehrt verhält sich der großturbulente Anteil. Im Haushalt der totalen kinetischen Energie wird im vertikalen und zeitlichen Mittel potentielle Energie in das Untersuchungsgebiet herein- und kinetische Energie hinaustransportiert. Insgesamt wird dabei Energie im Innern angereichert, die zur Umwandlung in verfügbare potentielle Energie zur Verfügung steht; die dominierenden Mengen hierzu liefern die großturbulenten Anteile.
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    Meteorology and atmospheric physics 23 (1974), S. 227-236 
    ISSN: 1436-5065
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    Topics: Geography , Physics
    Description / Table of Contents: Summary The object of this investigation is the relation between available potential energy and the height difference of the centers of mass for the actual and the reference state of the atmosphere. This difference is shown to be proportional to the available potential energy. If we choose a hydrostatically, stable stratified atmosphere which is uniform in the horizontal as the reference atmosphere, this height difference is a good indication of how little the actual atmosphere deviates from the uniform hydrostatic equilibrium state. Surprisingly, the difference over the whole globe is only about 10 m. In addition, a relation is demonstrated between available potential energy and that surface in the atmosphere which is formed by connecting the centers of mass of individual air columns.
    Notes: Zusammenfassung Es wird der Zusammenhang zwischen verfügbarer potentieller Energie und der Höhendifferenz der Schwerpunkte vom aktuellen und Referenzzustand der Atmosphäre untersucht. Dabei zeigt sich, daß diese Differenz direkt proportional der verfügbaren potentiellen Energie ist. Wählt man als Referenzzustand einen hydrostatisch stabilen, horizontal geschichteten Zustand der Atmosphäre, so gibt diese Höhendifferenz ein anschauliches Maß über die Abweichung des aktuellen Zustandes der Atmosphäre von der hydrostatischen Gleichgewichtslage an. Global gesehen ist diese Differenz erstaunlich gering; sie beträgt etwa 10 m. Weiters wird noch der Zusammenhang zwischen der verfügbaren potentiellen Energie und der „Schwerpunktfläche” der Atmosphäre, die durch die Höhen der Schwerpunkte der einzelnen Luftsäulen gebildet wird, aufgezeigt.
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  • 41
    ISSN: 1436-5065
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    Topics: Geography , Physics
    Description / Table of Contents: Zusammenfassung Unsere Studien über den Einfluß der aerologischen Feinstruktur-Parameter auf die vertikale Verteilung des Aerosols wurden planmäßig fortgesetzt. Das Hauptaugenmerk war auf den weitgehenden Abschluß der Herausarbeitung einer Parameterisierung der Beziehungen zwischen aerologischen Parametern einerseits und der vertikalen Scheindiffusion andererseits gerichtet. Diese Parameterisierung gründete sich a) auf die jüngsten verbesserten theoretischen Ableitungen des Austausch-Koeffizienten aus den gemessenen vertikalen Profilen der Partikelkonzentration, b) auf die Gesamtheit der seit Jahren gewonnenen Daten und somit c) auf hinreichende statistische Signifikanz. Daten: Kontinuierliche Registrierungen von RaB- und RaC-Konzentrationen in Luft in 740, 1800 und 3000 m Höhe und Berechnung der mittleren vertikalen Austauschkoeffizienten für die Schichten dazwischen; Registrierungen der Luftleitfähigkeiten und Aitkenkern-Konzentrationen in denselben Höhen. Anwendung all dieser Daten zur Berechnung der kontinuierlichen, vertikalen Profile der Aitkenkern-Konzentrationen aus den Luftleitfähigkeits-Profilen, die mit den Telemetrie-Systemen aufgenommen worden sind. Alle älteren und jüngsten Telemetrie-Meßfahrten, nämlich 2400 mit der Zugspitz-Seilbahn und 900 mit der Wank-Seilbahn, aus der Zeit von Juli 1970 bis Mitte Oktober 1972 wurden benutzt, um auf der inzwischen verbesserten theoretischen Basis die Austausch- und Diffusions-Koeffizienten zu berechnen. Die jeweils gleichzeitig erfaßten aerologischen Profile dienten zur Parametrisierung der Abhängigkeit des incremental exchange coefficients von der Feinstruktur aerologischer Parameter. Die erhaltenen Funktionen können in der Praxis direkt zur Bestimmung der schichtweisen Austauschintensität aus Radiosondenaufstiegen benutzt werden.
    Notes: Summary Studies in the effects of aerological fine-structure characteristics upon vertical distribution of aerosols were continued. Emphasis was put on largely concluding the development of a parametrization of the relationship between aerological parameters and vertical eddy aerosol diffusion. This parametrization is based (a) on a recently improved theoretical derivation of exchange coefficient from vertical profiles of particle concentration; (b) on the entirety of data obtained in several years; and thus (c) on adequate. Data: Continuous recording of RaB and RaC concentrations in the air at 740 m, 1780 m, and 3000 m a. s. l., and computation of mean vertical exchange coefficients for the strata between; recording of air conductivities and Aitken nucleus concentrations at the same levels. Application of all of these data in computing continuous vertical profiles of Aitken nucleus concentrations from air conductivity profiles taken by our telemetry systems: All earlier telemetry runs as well as the most recent ones, viz.: 2400 runs by Zugspitze cable car (1000–3000 m a. s. l.), and 900 runs by Wank cable car (740–1780 m), from the period of July 1970 through mid-October 1972, were used to compute the exchange and diffusion coefficients. The respective aerological profiles covered simultaneously were used for parametrization of the relationship of the incremental exchange coefficient with the fine structure of aerological parameters. In practice the functions obtained can directly be used to determine stratified exchange intensity from radiosonde ascents.
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    Monatshefte für Mathematik 78 (1974), S. 25-41 
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    Monatshefte für Mathematik 78 (1974), S. 42-50 
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    Monatshefte für Mathematik 78 (1974), S. 68-76 
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    Monatshefte für Mathematik 78 (1974), S. 117-130 
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    Monatshefte für Mathematik 78 (1974), S. 109-116 
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    Monatshefte für Mathematik 78 (1974), S. 131-146 
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    Monatshefte für Mathematik 78 (1974), S. 156-163 
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    Monatshefte für Mathematik 78 (1974), S. 215-222 
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    European journal of nutrition 13 (1974), S. 1-5 
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
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  • 55
    ISSN: 1436-6215
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary 1. It was attempted to investigate the consequences of obesity and slimming on the adenohypophyse, the thyroid and the adrenal cortex in rats. 2. Young male rats were fattened and slimmed down again under the least traumatizing conditions. 3. By selection a strain of rats could be isolated more easy to be fattened and more difficult to be slimmed down. This was already obtained in three generations and still more enhanced in two further generations. 4. During fattening the adenohypophyse of rats of the original strain showed a histological picture suggestive of a resting condition. During slimming the thyreotropic and the corticotropic cells seemed stimulated. In animals of the selected strain degenerative changes of these cells were observed in consequence of a long-lasting fattening. 5. The thyroid and the adrenal cortex of rats of the selected strain appeared less active than those of animals of the original strain. Fattening is followed by a decreased activity of the thyroid and the adrenal cortex. This was more conspicuous in rats of the selected strain than in those of the original strain. 6. Possible predisposing influence of these changes of the endocrines on obesity are discussed.
    Notes: Zusammenfassung 1. Es wurde versucht, die Folgen der alimentär bedingten Verfettung und Abmagerung auf die Hypophyse, die Schilddrüse und die Nebenniere der Ratte zu ergründen. 2. Junge männliche Ratten wurden unter schonenden Bedingungen gemästet und wieder abgemagert. 3. Durch Zuchtwahl konnte in drei Generationen ein Rattenstamm isoliert werden, der schneller verfettet und langsamer abmagert als der ursprüngliche Stamm. In zwei folgenden Generationen wurde diese Eigentümlichkeit durch Zuchtwahl weiter verstärkt. 4. Die Hypophyse zeigt bei Tieren des Ausgangsstammes Ruhebilder während der Verfettung und Anregungsbilder während der Abmagerung. Bei Tieren des ausgewählten Stammes zeigen sich infolge langfristiger Mast Degenereszenzbilder in einzelnen Zellen der Hypophyse. 5. Die Schilddrüse und die Nebenniere scheinen bei Tieren des ausgewählten Stammes weniger aktiv als bei Tieren des Ausgangsstammes. Die Mast hat signifikante zusätzliche Verminderung der Aktivität der Schilddrüse und der Nebennieren zur Folge. 6. Eventuelle prädisponierende Einflüsse der endokrinen Drüsen auf die Verfettung werden erwogen.
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  • 56
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Zusammenfassung Bei Hamstern unter verschiedenen Diätverhältnissen wurde die Größe des Gallensäurepools mittels einer Auswaschtechnik bestimmt. Hamster, die mit einer gallensteinfördernden Diät gefüttert wurden, hatten einen gegenüber den mit Normalnahrung behandelten Kontrolltieren leicht erhöhten Pool. Der Unterschied war hauptsächlich durch den kleineren Chenodeoxycholsäurepool der Kontrolltiere bedingt. Nach Cholezystektomie fand sich eine signifikante Verminderung des Gallensäurepools sowohl bei den mit gallensteinfördernden Diät gefütterten Hamstern wie auch bei den mit Normalkost gefütterten Kontrolltieren.
    Notes: Summary The size of the bile acid pool in hamsters under different dietary conditions was determined with a wash-out technique. Hamsters fed a gallstone-inducing diet had a somewhat larger pool than control animals fed chow. This difference was largely due to the smaller chenodeoxycholic acid pool in the controls. After cholecystectomy there was a significant decrease of the bile acid pool size both in hamsters fed a lithogenic diet and in chow-fed controls.
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    European journal of nutrition 13 (1974), S. 6-17 
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Notes: Zusammenfassung Mittelkettige Triglyceride unterscheiden sich auf Grund ihrer biochemischen und physikalischen Eigenschaften von den üblichen Nahrungsfetten. Durch die weitgehende Unabhängigkeit von der Pankreaslipase und den Gallensäuren, durch ihre rasche Resorption und durch die schnelle Energiebereitstellung stehen die mittelkettigen Triglyceride in der modernen Ernährung als wertvolles Diätetikum bei allen denjenigen Erkrankungen zur Verfügung, die mit Fettmalabsorption und Lymphabflußstörungen einhergehen. Auch der Einsatz bei der fettinduzierten Hyperlipidämie und bei der Hypercholesterinämie ist erfolgreich. In der vorliegenden Arbeit wird die klinische Wertigkeit dieser Fette sowie die verschiedensten Stoffwechselwirkungen diskutiert.
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    Description / Table of Contents: Summary Studies on nutrient supply and biochemical investigations on blood cholesterol state have been performed in 63 male and female persons living in five old people's homes. It has been found that a commercial margarine which was rich in linoleic acid lowered the cholesterol levels of all the volunteers by 12% and 28% respectively. The margarine had a content of linoleic acid of 31,8%.
    Notes: Zusammenfassung über 49 Wochen wurden in 5 Altenheimen Erhebungen über die Nährstoffzufuhr und biochemische Untersuchungen des Cholesterinblutstatus an 63 Personen beiderlei Geschlechts durchgeführt. In einem Kollektiv konnte durch Einführung einer linolsäurereichen handelsüblichen Delikateßmargarine der Serumcholesterinspiegel aller Probanden erheblich gesenkt werden. Die Durchschnittswerte sanken um 12% bei der zweiten und um 28% bei der dritten Blutentnahme. Die verabreichte Margarine hatte einen Linolsäuregehalt von 31,8%.
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    European journal of nutrition 13 (1974), S. 43-58 
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    Description / Table of Contents: Summary In a group of 38 patients was examined the effect of 0.5 g caffeine natrium bencoicum equivalent 250 mg pure caffeine. After getting a special diet without any medicaments profile-levels of the day were taken of free fatty acids, triglyceride and cholesterin. They were compared with the equivalent values, which were found at the same time the day later after the application of caffeine. There no exorbitant changes of the biological stimulators of the lipolysesystem were discovered. No therapeutical and dietetical consequences concerning the coffee or application of caffeine can be derived.
    Notes: Zusammenfassung An einem Kollektiv von 38 Patienten, akute Hepatitis n=16, chronische Hepatitis n=10 und Leberzirrhose n=12, wurde die Wirkung von 0,5 g Coffein natrium bencoicum — entsprechend 250 mg Coffein — geprüft. Nach diätetischer Vorbereitung und Unterlassung jeglicher medikamentöser Therapie wurden Leer-Tagesprofile (über 8 Stunden) von freien Fettsäuren (FFS), Triglyceriden (TG) und Cholesterin (Chol) erhoben und den entsprechenden Meßgrößen nach Coffeinapplikation gegenübergestellt. Dabei ergaben sich keine — die biologischen Stimulatoren überspielende — Veränderungen des Lypolysesystems. Therapeutische und diätetische Rückschlüsse auf den Kaffeegenuß (bzw. Coffeingabe) können nicht abgeleitet werden.
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    European journal of nutrition 13 (1974), S. 69-72 
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    European journal of nutrition 13 (1974), S. 72-72 
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  • 62
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The protein quality of some species of freshwater algae was determined by balance-tests with rats (table 1). The microalgal substances used for feeding had been subjected to short-term high-temperature treatment on a roller dryer, which causes an optimal cell disruption and consequently, a good protein digestibility. The green algaScenedesmus obliquus proved to be a plant protein source of best quality, as revealed by a PER of 3.21, a NPU of 68 and a BV of 81 (table 3). — Protein fromCoelastrum proboscideum is of good quality with values of 3.18 (PER), 59 (NPU) and 75 (BV). Depending on the culture medium abnormally high concentrations of non-essential N can be obtained in this alga, which influences negatively the value of the crude protein fraction in the rat-test. — The crude protein of the green algaUronema sp., the largest species of the above test series, is of comparably low quality, with protein values of 2.47 (PER), 45 (NPU) and 55 (BV).
    Notes: Zusammenfassung Die Proteinqualität einiger Algenarten des Süßwassers wurde in Ratten-Bilanzversuchen bestimmt (Tab. 1). Die verfütterten Mikroalgen-Substanzen waren mittels Feinschicht-Walzentrocknung kurzzeitig hocherhitzt worden, was einen optimalen Zellaufschluß und eine gute Eiweißverdaulichkeit bewirkt. Die GrünalgeScenedesmus obliquus erwies sich als eine pflanzliche Proteinquelle bester Qualität, gekennzeichnet durch eine PER von 3,21, eine NPU von 68 und eine BV von 81 (Tab. 3). — Von guter Qualität ist das Eiweiß der GrünalgeCoelastrum proboscideum, mit Werten von 3,18 (PER), 59 (NPU) bzw. 75 (BV). In Abhängigkeit vom Kulturmedium kann es bei dieser Alge zu abnorm hoher Konzentration von nichtessentiellem N kommen, was den Wert der Rohprotein-Fraktion im Rattentest negativ beeinflußt. — Das Roheiweiß der GrünalgeUronema sp., der größten Algenspezies der vorliegenden Testreihen, ist mit Proteinkennzahlen von 2,47 (PER), 45 (NPU) und 55 (BV) von vergleichsweise mäßiger Qualität.
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  • 63
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    Description / Table of Contents: Summary Two under deep frying conditions heated soyabean oils and the unheated oil were fed to rats at a concentration of 20% (w/w) in the food for 2 months. The animals were sacrificed and kidney fat, subcutaneous fat, and fat extracted from the liver were analysed. Whereas the heated frying fats contained 17% and 18% of dimeric triglycerides, as could be shown by gel permeation chromatography, the kidney as well as the subcutaneous fat was completely free of dimeric triglycerides. Fat isolated from the liver showed small amounts (<0.5%) of these compounds which, as far as we believe, do not originate from the heated fat fed to the animals since these compounds were present even in case of the animals which received the unheated oil. Kidney and subcutaneous fats were analysed by liquid chromatography and thin-layer chromatography w. r. t. the presence of polar components (total polar artefacts). The heated fats contained up to 27% and 31% of total polar artefacts, the unheated soyabean oil 6%, whereas in the body fats isolated only up to 3% could be detected. Kidney and subcutaneous fats were interesterified with methanol and the methylesters analysed by thin-layer and gel permeation chromatography. Dimeric fatty acid methyl-esters could be detected in the heated fats only but not in the body fats. This shows that intramolecular links between two fatty acids do not occur in the body fats. From all these results it is concluded that artefacts occurring in heated frying fats do not accumulate in adipose tissue after feeding them to the test animals.
    Notes: Zusammenfassung Zwei belastete sowie ein unbelastetes Sojaöl wurden über zwei Monate bei einem Anteil von 20 Gew.-% im Futter an Ratten verfüttert. Anschließend wurden die Nieren-, Subkutan- und Leberfette der Tiere untersucht. Während die verfütterten belasteten Bratfette lt. Gelpermeationschromatogramm (GPC) 17 und 18% dimere und höher molekulare Triglyceride enthielten, waren Substanzen dieses Molekulargewichts in den Nieren- und Subkutanfetten nicht und in den Leberfetten nur mit weniger als 0,5 % vorhanden. Mittels Liquid-(LC)- und Dünnschichtchromatographie (DC) wurden Nieren- und Subkutanfette auf polare Anteile untersucht. Sie waren in den verfütterten belasteten Bratfetten zu 27 und 31 % enthalten, im unbelasteten Bratfett zu 6% und in den Körperfetten zu maximal 3 %. Dimere Fettsäuren ließen sich auch in den als monomer erkannten Triglyceriden der Nieren- und Subkutanfette nicht nachweisen: Die aus diesen Fetten hergestellten Methylester enthielten lt. DC und GPC im Gegensatz zu dem Methylester aus einem belasteten Bratfett keine Methylester dimerer Fettsäuren. Damit ist auch eine intramolekulare Vernetzung der Fettsäuren auszuschließen. Diese Ergebnisse lassen den Schluß zu, daß die in belasteten Bratfetten vorhandenen Artefakte sich nach dem Verfüttern der Fette nicht in den Körperfetten der Versuchstiere anreichern.
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The influence of diverse fat diets (20%) on choleresis, rate of secretion of bile acids and transport of radioactive bile acids was investigated in rats. The fat of diet I contained saturated and mono-unsaturated fatty acids, diet II contained predominantly polyunsaturated fatty acids. Each diet was fed to a control group and to another group which received a single dose of cholic acid (300 mg/kg) per duodenal tube to stimulate choleresis. The diets were given for 14 days to reach a steady state. The experiment was then carried out by collecting the bile in 30-minute-fractions for 6 hours to obtain the data needed to derive the kinetic parameters. In rats fed diet II bile flow decreases quickly, after cannulation, but in the animals stimulated by administration of cholic acid bile secretion rises steeply and remains on a high level during the whole time observed. In comparison, the control rats fed saturated fatty acids have an increased bile flow for 4 to 5 hours; yet after stimulation of choleresis the bile flow rises poorly, and after the initial two hours no significant difference from controls on the same diet can be observed. There are significant changes in the concentration of bile acids. In the same animals on diet II bile acid concentration is at low level at the beginning and rises to 3-fold after administration of cholic acid. When saturated fatty acids are fed, the absolute and relative increase is less pronounced. In both diets the same maximal value (μmol/kg) is reached; that is the maximal capacity of bile acid secretion of the liver cell seems to be constant in our experimental conditions, and not influenced by diet. In animals on diet II radioactive cholic acid — applied by duodenal tube 1 hour after commencement — is secreted in the bile much more quickly and to a higher percent in comparison with diet I. From these results we can conclude that in rats fed diet II for 14 days the transport mechanism for bile acids of the enterohepatic circulation has more spare capacity than in rats on diet I. In animals fed diet II bile acids given additionally are transported and secreted with the bile and thus eliminated from the enterohepatic circulation more quickly.
    Notes: Zusammenfassung An Ratten wurde der Einfluß verschiedener fettreicher (20%) Diäten auf Gallensekretion, Gallensäurenausscheidung und Transport von radioaktiv markierten Gallensäuren untersucht, und zwar unter Normalbedingungen und bei Choleresereiz durch intraduodenale Applikation von Cholsäure (300 mg/kg) 1 Std. nach Versuchsbeginn. Nach 14tägiger Vorbehandlung mit der entsprechenden Diät (Diät I: Fette mit gesättigten und 1fach ungesättigten Fettsäuren; Diät II: Fette mit vorwiegend polyungesättigten Fettsäuren) wurde in 6stündigen Versuchen die Galle in 30-min-Fraktionen aufgefangen und so eine Kinetik der genannten Größen aufgestellt. Unter Diät II wird ein rascherer Rückgang des Galleflusses beobachtet, auf den Choleresereiz reagiert die Ratte mit steilem Anstieg der Gallensekretion. die während der weiteren Beobachtungszeit auf erhöhtem Niveau verläuft. Demgegenüber sezerniert die mit gesättigten Fettsäuren ernährte Ratte über 4–5 Std. ein größeres Gallevolumen und vermag dieses bei zusätzlichem Choleresereiz war zunächst mäßig zu steigern, im weiteren Verlauf können signifikante Unterschiede zum Kontrolltier mit gleicher Diät jedoch nicht festgestellt werden. Auffallende Unterschiede zeigen sich auch im Verhalten der Gallensäurenkonzentration: Diese liegt bei Ernährung mit polyungesättigten Fettsäuren zu Versuchsbeginn niedriger, nach Zufuhr von Cholsäure steigt sie auf das ca. 3fache an, während unter Diät I der absolute und prozentuale Zuwachs sehr viel weniger ausgeprägt sind. Unter beiden Diäten wird der gleiche Maximalwert erreicht (inμMol/ml), d. h., die absolute Sekretionskapazität der Leberzelle für Gallensäuren scheint unter unseren Versuchsbedingungen konstant zu sein. 1 Std. nach Versuchsbeginn intraduodenal applizierte, radioaktiv markierte Cholsäure wird unter Diät II wesentlich rascher und in größerem Umfang mit der Galle ausgeschieden. Diese Ergebnisse lassen den Schluß zu, daß bei Ratten nach 14tägiger Vorbehandlung mit Diät II die Transportkapazität des enterohepatischen Kreislaufs für Gallensäuren weniger ausgelastet ist als unter Diät I. Zusätzlich in den Darm applizierte Gallensäuren werden unter Diät II schneller transportiert und mit der Galle ausgeschieden, damit auch schneller eliminiert.
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary By application of chlorogenic acid into the stomach and the intestine of urethan-anaesthetized rats the substance was not detected in serum or bile, contrary to the observations after i. v. application. As the amount of chlorogenic acid applicated into stomach and intestine decreases with time and caffeic as well as quinic acid were identified, it is concluded that chlororganic acid is cleaved in stomach and intestine and is absorbed presumably in form of its primary fragments or further metabolits.
    Notes: Zusammenfassung In Untersuchungen an urethan-narkotisierten Ratten wurde nach Applikation von Chlorogensäure in den Magen und in den Darm im Gegensatz zur i. v. Injektion ein Erscheinen von Chlorogensäure im Blutserum und auch in der Galle nicht beobachtet. Da sich die in Magen und Darm eingegebene Chlorogensäuremenge zeitabhängig verringerte und gleichzeitig Kaffeesäure und Chinasäure nachgewiesen werden konnten, ist zu folgern, daß Chlorogensäure im Magen und Darm aufgespalten wird und in Form seiner primären Spaltprodukte bzw. weiterer Metabolisierungsprodukte resorbiert wird.
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    European journal of nutrition 13 (1974), S. 101-107 
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    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary After a scheme is provided of the well-known reactions of folates in the synthesis of the nucleic acids, results are given of some experiments with rats, in which thymin and adenin were added to their food. This food also contained methotrexate, in order to induce a state of folate deficiency. Neither the addition of 0.4% adenin nor of 0.2% thymin nor of both substances to the diets was able to prevent folate deficiency symptoms. The statistically significant differences between the results of the addition of thymin and adenin could be accounted for by differences in food consumption, rather than by preferential utilization of folate in thymidin synthesis.
    Notes: Zusammenfassung Nachdem ein Schema der bekannten Reaktionen von Folsäure in der Synthese der Nukleinsäuren gegeben wurde, werden die Ergebnisse einiger Versuche an Ratten mit Zusätzen von Thymin und Adenin zu ihrem Futter, das auch Amethopterin enthielt, um einen Folsäuremangel zu erzeugen, mitgeteilt. Der Zusatz von entweder 0,4% Adenin oder 0,2% Thymin oder von beiden Stoffen zu dem Futter zeigte sich in der Vorbeugung von Folsäuremangelsymptomen als wirksam. Die statistisch signifikanten Differenzen in den Ergebnissen der Zusätze von Thymin und Adenin sind eher durch eine Differenz im Futterverbrauch zu erklären als durch eine bevorzugte Verwendung von Folsäure für die Thymidinsynthese.
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  • 67
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The histopathological examination of 516 rats of two generations fed for whole life span deep-fried fats (partially hydrogenated peanut oil or soybean oil) showed no typical lesions according to the observations of all authors working in this field. Only the damages characteristical for normal old rats were observed. In all groups the most frequently occurring pathology were lung diseases, e.g. bronchopneumonia with extended abscess formation. Other main findings were kidney lesions in the sense of an uncharacteristic nephrosis. The incidence of liver pathology (hepatitis, necrosis, fatty infiltration) was similar in all groups and not related to the kind of treatment of the oils. Lesions of the gastro-intestinal tract were observed only rarely and there was no relation to the kind of thermal treatment of the oils. The malignant tumor rate was diminished by feeding the heated soybean oil, an observation as made by other authors.
    Notes: Zusammenfassung Die histologische Untersuchung von 516 Ratten aus 2 Generationen, die lebenslänglich mit Fritierfetten (partiell gehärtetes Erdnußöl und Sojaöl) in einer Dosis von 10% im Futter ernährt worden waren, ergab keine von der Norm abweichenden Befunde. Lediglich die für alte Ratten charakteristischen Organbefunde konnten in Übereinstimmung mit allen anderen über dieses Gebiet arbeitenden Autoren festgestellt werden. In allen Gruppen war der häufigste Befund Bronchopneumonien mit ausgedehnten Abszeßbildungen. Ein anderer häufig zu erhebender Befund waren Nierenveränderungen im Sinne einer uncharakteristischen Nephrose. Pathologische Leberbefunde (Hepatitis, Nekrosen, starke Verfettung) wurden in allen Gruppen praktisch gleichmäßig verteilt gefunden und waren unabhängig von der thermischen Behandlung der Fette. Schädigungen des Magen-Darm-Traktes traten nur sehr selten auf und zeigten keine Korrelation zu der Art der Behandlung der Fette. Die Rate an malignen Tumoren war — in Übereinstimmung mit Angaben anderer Autoren — bei den Gruppen, die thermisch behandelte Sojaöle erhalten hatten, kleiner als in der Kontrollgruppe, der das unerhitzte Sojaöl verfüttert worden war.
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  • 68
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    European journal of nutrition 13 (1974), S. 142-142 
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
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  • 69
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
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  • 70
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    European journal of nutrition 13 (1974), S. 143-144 
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
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  • 71
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Using gastric juice samples obtained from 25 patients before and after pentagastrin stimulation a method was prepared to define digestibility of food proteins. A parallel investigation of alcohol-extractable proteolysis products by aid of two quantitative methods for protein measurement gives a view about the composition of that soluble part of protein after gastric digestion and allows a classification of the food proteins in response to their digestibility. Method of investigation, results and their importance for further studies are discussed.
    Notes: Zusammenfassung Im Rahmen einer Vergleichsstudie mit Magensaftproben von 25 Patienten, gewonnen vor und nach maximaler Stimulation mit Pentagastrin, wurde ein Verfahren zur qualitativen und quantitativen Definition der Verdaulichkeit von Nahrungsproteinen ausgearbeitet. Es wurde gezeigt, daß die parallele Untersuchung alkoholextrahierbarer Spaltprodukte mit Hilfe zweier klassischer Eiweißbestimmungsverfahren wertvolle Aussagen über die Zusammensetzung dieser Eiweißfragmente liefert und eine Klassifizierung der Nahrungseiweißkörper entsprechend ihrer Verdaulichkeit ermöglicht. Die Methode der Untersuchung, das Ergebnis und seine Bedeutung für die Klinik werden diskutiert.
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  • 72
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The course of cholesterol-7α-hydroxylase activity was observed for 14 days in 3 groups of rats on 20% fat diets which were of different fatty acid compositions. Determinations were done at 09.00 and 23.00 hr. In the controls the circadian variations of the enzyme were confirmed. Feeding of saturated fatty acids lead to a reduced 7α-hydroxylation of cholesterol in the dark period, whereas feeding of polyunsaturated fatty acids (13% as well as 56% of total fatty acids) showed an enzyme activity unchanged in the dark period but slightly enhanced in the light period.
    Notes: Zusammenfassung Der Verlauf der Cholesterin-7α-Hydroxylase-Aktivität wurde während 14 Tagen an 3 Gruppen fettreich (20%) ernährter Ratten beobachtet (Messungen jeweils um 9.00 und 23.00 Uhr), wobei die einzelnen Diäten sich in der Fettsäurenzusammensetzung unterschieden. Während die Werte der Kontrollgruppe den Circadianrhythmus des untersuchten Enzyms bestätigten, führt Ernährung mit gesättigten Fettsäuren zu einem Absinken der 7α-Hydroxylierung des Cholesterins in der Dunkelphase. Dagegen weisen die Diäten mit polyungesättigten Fettsäuren (13% bzw. 56% des Fettsäurengehaltes) in der Dunkelphase unveränderte, in der Hellphase eher erhöhte Cholesterin-7α-Hydroxylase-Aktivität auf.
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  • 73
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    European journal of nutrition 13 (1974), S. 165-171 
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary Cocoa products generally contain considerable amounts of methylxanthines, 80–90% being theobromine and 10–20% being caffeine. These substances may stimulate the central nervous system, the performance of the striated muscles and the renal function. When giving the methylxanthines in form of cocoa products, the mentioned effects are less pronounced than after application of equally dosed pure alcaloids. This difference may be explained by an impaired absorption of the substances due to the presence of polyhydroxyphenols and/or lipids in the cocoa products. When giving 20 mg/kg caffeine and 80 mg/kg theobromine to the mouse, i. e. in the naturally occurring relation, the stimulating effects of caffeine are enhanced after a transitory decrease when compared with those after caffeine alone. It is assumed that at first the stimulation after caffeine is inhibited by theobromine, but subsequently is enhanced by the later formed theobromine metabolites. Side effects of cocoa products have been observed in man in form to headache, trembling and sweating only after consumption of extremely high doses, e. g. 50–100 g cocoa poudre per day; they are essentially referred to the action of theobromine.
    Notes: Zusammenfassung In Kakaoprodukten werden regelmäßig größere Mengen an Methylxanthinen gefunden, von denen etwa 80–90% auf Theobromin und 10–20% auf Coffein entfallen. Diese Substanzen haben bei Aufnahme mit den Kakaoprodukten einen fördernden Einfluß auf das Zentralnervensystem, auf die Muskelleistung und die Nierenfunktion. Die Methylxanthine wirken allerdings, in Form der Kakaoprodukte gegeben, erheblich schwächer als die Reinalkaloide, was auf die gleichzeitige Anwesenheit von Gerbstoffen und/oder Fettsubstanzen zurückge-führt wird. Durch gleichzeitige Gabe von Coffein und Theobromin in einem den Kakaoprodukten entsprechenden Verhältnis war im Tierversuch eine Beeinflussung der zentralerregenden Wirkung von Coffein nachweisbar in dem Sinne, daß zunächst eine Abschwächung, später aber eine Verstärkung des Coffeineffektes auftrat. Die Coffeinwirkung soll dabei durch Theobromin in hemmendem Sinne, durch später entstehende Theobrominmetaboliten in förderndem Sinne beeinflußt werden. Kakaoprodukte führen erst in extrem hohen Dosierungen (50 bis 100 g Kakaopulver täglich) zu Nebenwirkungen in Form von Kopfschmerzen, Zittern und Schweißausbrüchen, die im wesentlichen dem Theobromin zugeschrieben werden.
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  • 74
    ISSN: 1436-6215
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Notes: Zusammenfassung Es wurden Gehaltsveränderungen von Sulfhydrylgruppen in Milch während ihrer Erhitzung beobachtet. Diese Veränderungen wurden mit der Hitzedenaturierung von Molkeneiweiß in Zusammenhang gebracht. Untersucht wurden ferner die Reduktionseigenschaften der Milch unter dem Einfluß von den SH-Gruppen. Auch die Qualität und Haltbarkeit des Vollmilchpulvers, das mit einer größeren Anzahl von SH-Gruppen enthaltenden Verbindungen bereichert worden war, wurden untersucht. In Rohmilch wurden keine freien SH-Gruppen festgestellt, ihr höchster Gehalt wurde jedoch in der Milch nachgewiesen, die während 1 min bei 90° C erhitzt wurde. Es wurde auch festgestellt, daß die intensive Zunahme von SH-Gruppen mit dem Denaturierungsgrad desβ-Laktoglobulin korreliert. Es kam zum Vorschein, daß die freien SH-Gruppen die Zunahme der Reduktionseigenschaften von Milch in bestimmter Weise beeinflussen. Gleichzeitig wurde nachgewiesen, daß die Veränderungen in den Reduktionseigenschaften der Milch, die während der Erhitzung auftreten, durch Entstehung anderer Reduktionsverbindungen verursacht werden. Die Zunahme von SH-Gruppen und Reduktionseigenschaften im Milchpulver, verursacht durch die Zugabe von Verbindungen mit höherem SH-Gruppen-Gehalt, übt eine hemmende Wirkung auf die Oxydationsveränderungen des Milchpulverfettes während der Aufbewahrung aus. Es wurde festgestellt, daß die Hemmung des Fettoxydationsvorganges im Milchpulver durch den Gesamtgehalt an Reduktionsstoffen und nicht nur durch die SH-Gruppen entscheidend beeinflußt wird.
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